1) The document describes an experimental study to determine the dynamic characteristics of a vibration-driven robot.
2) The robot consists of a shaker connected via springs to a chassis, which is propelled by resonance vibrations from the shaker's rotating masses. Accelerometers were mounted on the shaker and chassis to record vibrations.
3) A series of experiments were conducted with the chassis fixed to measure the free damped oscillations of the shaker. The natural frequency, spring constant, damping coefficient and other parameters were calculated from the acceleration data using equations of motion and logarithmic decrement.
This document summarizes a research paper that proposes a new vibration propulsion system for powering a small mobile robot. The system uses two counter-rotating eccentric masses, similar to the Dean drive, to excite an oscillating inner frame attached to an outer frame by springs. Wheels on the outer frame can be driven forward due to inertial and friction forces generated by the oscillating system. The document presents the dynamic model of the system and derives the governing differential equation. Experimental testing showed the system could successfully propel a robot vehicle and generate a maximum towing force of 8.5N while weighing 25N itself. Further improvements to increase propulsion are recommended.
The document describes the design of a slider-crank leg mechanism for a mobile hopping robotic platform. The mechanism uses a slider-crank mechanism to convert continuous motor rotation into piston motion, which impacts the ground to generate hopping locomotion. A mechanical clutch trigger mechanism was developed to control the impact timing and maintain a constant transmission angle for repeated hopping. Dynamic analysis was performed to determine the optimal position of the clutch trigger mechanism to maximize hopping height. Experimental validation was conducted, and future work on a two degree-of-freedom leg design is proposed.
Analysis of Variable Freedom Jumping Robot Based on Tripping and Singular Mec...IJRES Journal
:J
umping robot has a good capability of passing unstructured environment barriers, it also has a wide
range of applications in anti-disaster relief, military reconnaissance, anti-terrorism and other fields. A new
jumping robot is proposed and it is composed of energy transformation mechanism and singular point support
mechanism . The transformation of topology and DOF in different jumping states are researched. The
mechanism has the characteristics of short duration of action, high energy conversion rate and big instant impact
force on the ground. It provides a theoretical basis and foundation for further innovation and research .
This document presents the design and development of a dual mode EMG-controlled robotic orthosis to assist stroke patients in rehabilitation. The robot can operate in two control modes: 1) using predefined reference trajectories to control joint movement, and 2) using EMG signals to control joint direction. A dynamic model of the robot is derived using Lagrange's equations. The dual mode control system is implemented and tested in simulation and experiments. Results show the robot can successfully be controlled by both reference trajectories and EMG signals to assist in gait rehabilitation for stroke patients.
The article gives the experimental results of the processes occurring in the combined system of traction and magnetic suspension, which was implemented on the basis of the linear switched reluctance motor. The goal of the research is to examine the possibility to combine the levitation and traction functions within one unit. The full- function physical model of the transport system with the magnetic suspension has been produced for experimental verification of the development concept for the combined system of traction and magnetic suspension. The research tests have been performed at the track structure with the limited length in order to study the processes, occurring in the most complicated start-up mode, when the discrete behavior of current in windings has the disturbance effect on the object levitation. The oscillograms of electromechanical transition processes, showing the mutual influence of traction subsystems and a suspension, are provided. The results of researches have illustrated dramatically that the development concept of the combined system of traction and magnetic suspension, based on the linear switched reluctance motor, is absolutely real. Further researches should be aimed at improving the system characteristics by reducing the mutual influence of levitation and traction processes.
Wheeled robots are often utilized for various remote sensing and telerobotic applications because of their ability to navigate through dynamic environments, mostly under the partial control of a human operator. To make these robots capable to traverse through terrains of rough and uneven topography, their driving mechanisms and controllers must be very efficient at producing and controlling large mechanical power with great precision in real-time, however small the robot may be. This paper discusses an approach for designing a quad-wheeled robot, which is wirelessly controlled with a personal computer (PC) by medium-range radio frequency (RF) transceiver, to navigate through unpaved paths with little or no difficulty. An efficient servo-controlled Ackerman steering mechanism and a high-torque driving power-train were developed. The robot’s controller is programmed to receive and respond to RF control signals from the PC to perform the desired motions. The dynamics of the robot’s drivetrain is modeled and analyzed on MATLAB to predict its performances. The robot was tested on various topographies to determine its physical capabilities. Results show that the robot is capable of non-holonomically constrained motions on rough and uneven terrains.
Science project on Maglev Trains By Ardhenduardhendu03
This document discusses a science project about maglev trains. It begins by defining maglev trains as using magnetic levitation to move vehicles along a guideway without touching the ground. It then provides details on the history and development of maglev technology, describing early patents from the 1900s and the first commercial maglev system introduced in 1984 in Birmingham, England. The document also explains the key technologies behind maglev trains, including electromagnetic and electrodynamic suspension systems as well as linear motor propulsion. It compares maglev trains to conventional trains and notes maglev's benefits like higher potential speeds, less noise, and reduced maintenance needs.
This document summarizes a research paper that proposes a new vibration propulsion system for powering a small mobile robot. The system uses two counter-rotating eccentric masses, similar to the Dean drive, to excite an oscillating inner frame attached to an outer frame by springs. Wheels on the outer frame can be driven forward due to inertial and friction forces generated by the oscillating system. The document presents the dynamic model of the system and derives the governing differential equation. Experimental testing showed the system could successfully propel a robot vehicle and generate a maximum towing force of 8.5N while weighing 25N itself. Further improvements to increase propulsion are recommended.
The document describes the design of a slider-crank leg mechanism for a mobile hopping robotic platform. The mechanism uses a slider-crank mechanism to convert continuous motor rotation into piston motion, which impacts the ground to generate hopping locomotion. A mechanical clutch trigger mechanism was developed to control the impact timing and maintain a constant transmission angle for repeated hopping. Dynamic analysis was performed to determine the optimal position of the clutch trigger mechanism to maximize hopping height. Experimental validation was conducted, and future work on a two degree-of-freedom leg design is proposed.
Analysis of Variable Freedom Jumping Robot Based on Tripping and Singular Mec...IJRES Journal
:J
umping robot has a good capability of passing unstructured environment barriers, it also has a wide
range of applications in anti-disaster relief, military reconnaissance, anti-terrorism and other fields. A new
jumping robot is proposed and it is composed of energy transformation mechanism and singular point support
mechanism . The transformation of topology and DOF in different jumping states are researched. The
mechanism has the characteristics of short duration of action, high energy conversion rate and big instant impact
force on the ground. It provides a theoretical basis and foundation for further innovation and research .
This document presents the design and development of a dual mode EMG-controlled robotic orthosis to assist stroke patients in rehabilitation. The robot can operate in two control modes: 1) using predefined reference trajectories to control joint movement, and 2) using EMG signals to control joint direction. A dynamic model of the robot is derived using Lagrange's equations. The dual mode control system is implemented and tested in simulation and experiments. Results show the robot can successfully be controlled by both reference trajectories and EMG signals to assist in gait rehabilitation for stroke patients.
The article gives the experimental results of the processes occurring in the combined system of traction and magnetic suspension, which was implemented on the basis of the linear switched reluctance motor. The goal of the research is to examine the possibility to combine the levitation and traction functions within one unit. The full- function physical model of the transport system with the magnetic suspension has been produced for experimental verification of the development concept for the combined system of traction and magnetic suspension. The research tests have been performed at the track structure with the limited length in order to study the processes, occurring in the most complicated start-up mode, when the discrete behavior of current in windings has the disturbance effect on the object levitation. The oscillograms of electromechanical transition processes, showing the mutual influence of traction subsystems and a suspension, are provided. The results of researches have illustrated dramatically that the development concept of the combined system of traction and magnetic suspension, based on the linear switched reluctance motor, is absolutely real. Further researches should be aimed at improving the system characteristics by reducing the mutual influence of levitation and traction processes.
Wheeled robots are often utilized for various remote sensing and telerobotic applications because of their ability to navigate through dynamic environments, mostly under the partial control of a human operator. To make these robots capable to traverse through terrains of rough and uneven topography, their driving mechanisms and controllers must be very efficient at producing and controlling large mechanical power with great precision in real-time, however small the robot may be. This paper discusses an approach for designing a quad-wheeled robot, which is wirelessly controlled with a personal computer (PC) by medium-range radio frequency (RF) transceiver, to navigate through unpaved paths with little or no difficulty. An efficient servo-controlled Ackerman steering mechanism and a high-torque driving power-train were developed. The robot’s controller is programmed to receive and respond to RF control signals from the PC to perform the desired motions. The dynamics of the robot’s drivetrain is modeled and analyzed on MATLAB to predict its performances. The robot was tested on various topographies to determine its physical capabilities. Results show that the robot is capable of non-holonomically constrained motions on rough and uneven terrains.
Science project on Maglev Trains By Ardhenduardhendu03
This document discusses a science project about maglev trains. It begins by defining maglev trains as using magnetic levitation to move vehicles along a guideway without touching the ground. It then provides details on the history and development of maglev technology, describing early patents from the 1900s and the first commercial maglev system introduced in 1984 in Birmingham, England. The document also explains the key technologies behind maglev trains, including electromagnetic and electrodynamic suspension systems as well as linear motor propulsion. It compares maglev trains to conventional trains and notes maglev's benefits like higher potential speeds, less noise, and reduced maintenance needs.
PNEUMATIC VEHICLE ACTIVE SUSPENSION SYSTEM USING PID CONTROLLERTushar Tambe
The slide contains the simulation of pneumatic active suspension behavior on different road surface. These results shows the active suspension with controllers works effectively,if feedback loop is provided.
A Design Of Omni-Directional Mobile Robot Based On Mecanum WheelsIJRESJOURNAL
ABSTRACT:As one of the important branch of mobile robotics, wheel mobile robot has long been paid atten tion to by the research people at home and abroad for its high load ability, positioning accuracy, high efficiency, simple control, etc. Mobile robot has close relation to many technologies suc-h as control theory, computer tech nology, sensor technology, etc. Therefore, research on the mobile robot has important significance
Development of a quadruped mobile robot and its movement system using geometr...journalBEEI
As the main testbed platform of Artificial Intelligence, the robot plays an essential role in creating an environment for industrial revolution 4.0. According to their bases, the robot can be categorized into a fixed based robot and a mobile robot. Current robotics research direction is interesting since people strive to create a mobile robot able to move in the land, water, and air. This paper presents development of a quadruped mobile robot and its movement system using geometric-based inverse kinematics. The study is related to the movement of a four-legged (quadruped) mobile robot with three Degrees of Freedom (3 DOF) for each leg. Because it has four legs, the movement of the robot can only be done through coordinating the movements of each leg. In this study, the trot gait pattern method is proposed to coordinate the movement of the robot's legs. The end-effector position of each leg is generated by a simple trajectory generator with half rectified sine wave pattern. Furthermore, to move each robot's leg, it is proposed to use geometric-based inverse kinematic. The experimental results showed that the proposed method succeeded in moving the mobile robot with precision. Movement errors in the translation direction are 1.83% with the average pose error of 1.33 degrees, means the mobile robot has good walking stability.
This document analyzes the suspension system of an automobile modeled as a two-degree-of-freedom spring-mass-damper system. Equations of motion were derived using Lagrange's equations and modeled in SIMULINK. Natural frequencies were found to be 5.1 rad/s and 6.5 rad/s. Increasing damping reduced bounce by 3x10-3 m to 1x10-3 m and pitch by 5x10-4 m to less than 1x10-4 m. MATLAB modal analysis verified results and natural frequencies were compared.
This document discusses the design and implementation of a DELTA parallel robot. It describes the key components of a DELTA robot including the triangular base with three arms attached at uniform joints. Each arm is connected to an actuator and separated by 120 degrees. The robot consists of two links where a pair of parallel bars comprises the lower link, restricting movement to three translations along the X, Y, and Z axes. Popular applications of DELTA robots include high-speed packaging and medical/pharmaceutical uses due to their stiffness. Several variants of DELTA robots have been developed with different degrees of freedom.
1) Maglev trains use powerful electromagnets and magnetic levitation to float above a guideway and propel trains at speeds over 300 mph without friction from wheels on tracks.
2) There are two main types of maglev systems - electromagnetic suspension systems which use electromagnets to levitate the train, and electrodynamic suspension systems which use superconducting electromagnets and levitate higher.
3) The first commercial maglev line opened in Shanghai in 2003 and connects the city center to the airport in under 10 minutes, while a new line is planned between Shanghai and Hangzhou.
Potential Development of Vehicle Traction Levitation Systems with Magnetic Su...IAES-IJPEDS
This document analyzes the potential development of vehicle traction levitation systems with magnetic suspension. It discusses how early systems had separate components for levitation, guidance, and traction, but development has moved towards integrating these functions. One example is a linear synchronous motor that combines levitation, guidance, and traction in a single module. Further simplification may involve using linear switched reluctance motors, which could merge levitation, traction, and guidance functions using a single power supply. The forecast is that simple systems using switched reluctance motors may allow high-speed magnetic levitation vehicles to be more widely implemented commercially.
This document analyzes an axial-flux permanent magnet synchronous machine with contra-rotating rotors under unbalanced load conditions using 3D finite element analysis. It discusses how the back electromotive force (EMF) produced by each rotor combines to produce a distorted total back EMF when the rotors are at different angular positions. 3D FEA is used to model the machine and simulate its operation under unbalanced loads to obtain characteristics of the back EMF and torque production. The analysis aims to better understand performance issues like torque ripple and current oscillation that occur under unbalanced loads.
This document describes research on designing mechatronic systems for human balance rehabilitation. It discusses key human balance systems - vision, vestibular, and somatosensory systems. It then introduces the concept of Zero Moment Point (ZMP), which is important for bipedal robot balance and gait analysis. ZMP represents the point where the total momentum of a mechanism is zero. The document explains how to calculate ZMP and compares it to the Center of Pressure. Maintaining the ZMP inside the support polygon is necessary for dynamic stability. This research aims to apply insights into human balance maintenance to develop rehabilitation technologies.
This document discusses robust control of rotor systems with active magnetic bearings (AMBs). It begins with an introduction to AMBs and their applications. It then describes the system dynamics, including the magnetic bearing model and rotor dynamics equations of motion. It discusses robust controller design to stabilize the system despite model uncertainties. Frequency weighting and modeling uncertainty from parameters, neglected dynamics, and nonlinearities are addressed. Numerical simulations are presented to demonstrate the control approach.
Maglev, or magnetic levitation, is a transportation system that uses magnetic fields to levitate, guide and propel vehicles such as trains at high speeds without making contact with the guideway. Maglev trains can travel at speeds over 300 mph. Maglev works by using magnets to both levitate the train above the guideway and propel it using linear induction motors or linear synchronous motors. Maglev trains have benefits like very high speeds, low energy usage, nearly silent operation, very low maintenance costs and improved safety over conventional trains. Current maglev projects exist in Germany, Japan and other countries to develop this promising transportation technology.
1. The document describes the process of identifying key parameters for modelling a quadrotor drone.
2. Two custom test rigs were designed to measure the thrust coefficient, torque coefficient, and throttle command relation parameters.
3. Tests were conducted to determine values for the thrust coefficient, torque coefficient, throttle command relation, motor time constant, and mass moments of inertia for different quadrotor components.
4. The identified parameters will be used to accurately represent the quadrotor in simulations for controller design and evaluation.
This document summarizes a study that models and simulates an electric vehicle powered by a proton exchange membrane (PEM) fuel cell. The proposed system includes a PEM fuel cell, three-phase induction motor, inverter, and speed controller. Neural network models are used for the PEM fuel cell and vehicle. Simulation results show the induction motor's rotor speed tracks the reference speed provided by the speed controller. When the motor reaches a constant speed, the stator voltage and frequency decrease. The simulations also demonstrate the motor's response when accelerating from low to high speeds and vice versa. The study aims to analyze the induction motor's performance when powered by a PEM fuel cell for an electric vehicle.
Maglev trains use magnetic levitation to move along guideways without touching the ground. This reduces friction and allows for higher speeds. The fastest commercial train is the Shanghai Maglev, which reaches 430 km/h. Maglev trains move more smoothly than wheeled trains and are less affected by weather. While more expensive to build initially, maglev systems have lower maintenance costs than conventional trains. Only a few commercial maglev lines have been built, but many countries are researching the technology further.
The document discusses magnetic levitation (Maglev) trains. It begins by defining Maglev as using magnetic levitation to suspend, guide, and propel trains using magnets. It then explains the basic principles of levitation, propulsion, and lateral guidance that Maglev trains use to operate at high speeds. This includes using magnets to levitate the train 10 cm above the track and linear motors in the guideway to propel the train electromagnetically. The document also discusses the technologies, merits, and demographics of existing and planned Maglev systems around the world.
The document describes an All-Terrain Autonomous Vehicle (ATAV) designed and built for a class project. The ATAV uses a tank-style continuous track chassis powered by two motors controlled by an Arduino microcontroller. An ultrasonic sensor mounted on a servo detects obstacles and allows the ATAV to navigate around them to reach a target location. The ATAV was designed in phases, testing the drivetrain, integrating sensors, and adding localization functions to enable autonomous navigation between start and end points while avoiding obstacles. Testing showed the ATAV could successfully detect and maneuver around obstacles to reach its target location.
Maglev trains are the fastest trains in the world! Maglev is short for magnetic levitation which basic principles involve the use of magnetism to levitate an object.
EU-Cycle is a self balancing electric unicycle. A regular unicycle is powered by pedal and is balanced by a rider, whilst the EU-Cycle runs by an electric motor and balance by control system in the roll direction. The simple thing to do by rider is to lean forward for acceleration, to lean backward for braking. EU-Cycle is designed as to be a fast and portable means of transport among crowded area, home and office. Therefore, The EU-Cycle gives tough challenge to the unicycle. EU-Cycle has attracted print media including future stories in radio, television. Thus in addition to successful development of EU-Cycle in urban use, the project has to implement the EU-cycle as an educative device.
it is all about the working and little bit of history of the magnetic trains,
its a collection of knowledge,
find the references at end for more information
The document summarizes research on using chitosan to remove copper from wastewater. Chitosan is a biopolymer that can effectively sorb and remove copper. The study found that copper removal by chitosan increased with contact time until equilibrium was reached at 140 minutes. Copper removal also increased with increasing copper concentration and temperature, indicating the process is endothermic. Kinetic data showed the removal follows first-order kinetics. Thermodynamic calculations found the process is spontaneous with increasing temperature based on negative Gibbs free energy values and positive enthalpy changes. Copper uptake increased with increasing pH from 2 to 6.5. Overall, the research demonstrates chitosan is an effective and low-cost adsorb
This document summarizes methods for producing metal foams from aluminum alloys. It discusses direct foaming which injects gas into molten metal and indirect foaming using solid precursors. Direct foaming is commercially used but indirect foaming offers more control over pore structure. The document also outlines properties of aluminum foam including low density, stiffness, energy absorption and strength. Applications mentioned are lightweight construction, reinforcement of polymers, and use as cores in castings. Challenges remain in producing foams with uniform, controlled pore structures.
A Cost Estimation Model For Reuse Based Software ProgramIOSR Journals
This document presents a cost estimation model for a software reuse program. It proposes estimating costs at multiple levels - component, domain, application, and corporate. Costs include development, overhead, integration, and maintenance. The model is demonstrated using a hypothetical software company that develops reusable components from 2007-2010. Component size, availability, strategies, scale, standardization, and complexity are identified as factors that affect costs. Equations are provided to estimate costs at each level based on variables like component size, salary, reuse metrics, and probability of component availability. Graphs show relationships between various cost-affecting factors and total application costs.
PNEUMATIC VEHICLE ACTIVE SUSPENSION SYSTEM USING PID CONTROLLERTushar Tambe
The slide contains the simulation of pneumatic active suspension behavior on different road surface. These results shows the active suspension with controllers works effectively,if feedback loop is provided.
A Design Of Omni-Directional Mobile Robot Based On Mecanum WheelsIJRESJOURNAL
ABSTRACT:As one of the important branch of mobile robotics, wheel mobile robot has long been paid atten tion to by the research people at home and abroad for its high load ability, positioning accuracy, high efficiency, simple control, etc. Mobile robot has close relation to many technologies suc-h as control theory, computer tech nology, sensor technology, etc. Therefore, research on the mobile robot has important significance
Development of a quadruped mobile robot and its movement system using geometr...journalBEEI
As the main testbed platform of Artificial Intelligence, the robot plays an essential role in creating an environment for industrial revolution 4.0. According to their bases, the robot can be categorized into a fixed based robot and a mobile robot. Current robotics research direction is interesting since people strive to create a mobile robot able to move in the land, water, and air. This paper presents development of a quadruped mobile robot and its movement system using geometric-based inverse kinematics. The study is related to the movement of a four-legged (quadruped) mobile robot with three Degrees of Freedom (3 DOF) for each leg. Because it has four legs, the movement of the robot can only be done through coordinating the movements of each leg. In this study, the trot gait pattern method is proposed to coordinate the movement of the robot's legs. The end-effector position of each leg is generated by a simple trajectory generator with half rectified sine wave pattern. Furthermore, to move each robot's leg, it is proposed to use geometric-based inverse kinematic. The experimental results showed that the proposed method succeeded in moving the mobile robot with precision. Movement errors in the translation direction are 1.83% with the average pose error of 1.33 degrees, means the mobile robot has good walking stability.
This document analyzes the suspension system of an automobile modeled as a two-degree-of-freedom spring-mass-damper system. Equations of motion were derived using Lagrange's equations and modeled in SIMULINK. Natural frequencies were found to be 5.1 rad/s and 6.5 rad/s. Increasing damping reduced bounce by 3x10-3 m to 1x10-3 m and pitch by 5x10-4 m to less than 1x10-4 m. MATLAB modal analysis verified results and natural frequencies were compared.
This document discusses the design and implementation of a DELTA parallel robot. It describes the key components of a DELTA robot including the triangular base with three arms attached at uniform joints. Each arm is connected to an actuator and separated by 120 degrees. The robot consists of two links where a pair of parallel bars comprises the lower link, restricting movement to three translations along the X, Y, and Z axes. Popular applications of DELTA robots include high-speed packaging and medical/pharmaceutical uses due to their stiffness. Several variants of DELTA robots have been developed with different degrees of freedom.
1) Maglev trains use powerful electromagnets and magnetic levitation to float above a guideway and propel trains at speeds over 300 mph without friction from wheels on tracks.
2) There are two main types of maglev systems - electromagnetic suspension systems which use electromagnets to levitate the train, and electrodynamic suspension systems which use superconducting electromagnets and levitate higher.
3) The first commercial maglev line opened in Shanghai in 2003 and connects the city center to the airport in under 10 minutes, while a new line is planned between Shanghai and Hangzhou.
Potential Development of Vehicle Traction Levitation Systems with Magnetic Su...IAES-IJPEDS
This document analyzes the potential development of vehicle traction levitation systems with magnetic suspension. It discusses how early systems had separate components for levitation, guidance, and traction, but development has moved towards integrating these functions. One example is a linear synchronous motor that combines levitation, guidance, and traction in a single module. Further simplification may involve using linear switched reluctance motors, which could merge levitation, traction, and guidance functions using a single power supply. The forecast is that simple systems using switched reluctance motors may allow high-speed magnetic levitation vehicles to be more widely implemented commercially.
This document analyzes an axial-flux permanent magnet synchronous machine with contra-rotating rotors under unbalanced load conditions using 3D finite element analysis. It discusses how the back electromotive force (EMF) produced by each rotor combines to produce a distorted total back EMF when the rotors are at different angular positions. 3D FEA is used to model the machine and simulate its operation under unbalanced loads to obtain characteristics of the back EMF and torque production. The analysis aims to better understand performance issues like torque ripple and current oscillation that occur under unbalanced loads.
This document describes research on designing mechatronic systems for human balance rehabilitation. It discusses key human balance systems - vision, vestibular, and somatosensory systems. It then introduces the concept of Zero Moment Point (ZMP), which is important for bipedal robot balance and gait analysis. ZMP represents the point where the total momentum of a mechanism is zero. The document explains how to calculate ZMP and compares it to the Center of Pressure. Maintaining the ZMP inside the support polygon is necessary for dynamic stability. This research aims to apply insights into human balance maintenance to develop rehabilitation technologies.
This document discusses robust control of rotor systems with active magnetic bearings (AMBs). It begins with an introduction to AMBs and their applications. It then describes the system dynamics, including the magnetic bearing model and rotor dynamics equations of motion. It discusses robust controller design to stabilize the system despite model uncertainties. Frequency weighting and modeling uncertainty from parameters, neglected dynamics, and nonlinearities are addressed. Numerical simulations are presented to demonstrate the control approach.
Maglev, or magnetic levitation, is a transportation system that uses magnetic fields to levitate, guide and propel vehicles such as trains at high speeds without making contact with the guideway. Maglev trains can travel at speeds over 300 mph. Maglev works by using magnets to both levitate the train above the guideway and propel it using linear induction motors or linear synchronous motors. Maglev trains have benefits like very high speeds, low energy usage, nearly silent operation, very low maintenance costs and improved safety over conventional trains. Current maglev projects exist in Germany, Japan and other countries to develop this promising transportation technology.
1. The document describes the process of identifying key parameters for modelling a quadrotor drone.
2. Two custom test rigs were designed to measure the thrust coefficient, torque coefficient, and throttle command relation parameters.
3. Tests were conducted to determine values for the thrust coefficient, torque coefficient, throttle command relation, motor time constant, and mass moments of inertia for different quadrotor components.
4. The identified parameters will be used to accurately represent the quadrotor in simulations for controller design and evaluation.
This document summarizes a study that models and simulates an electric vehicle powered by a proton exchange membrane (PEM) fuel cell. The proposed system includes a PEM fuel cell, three-phase induction motor, inverter, and speed controller. Neural network models are used for the PEM fuel cell and vehicle. Simulation results show the induction motor's rotor speed tracks the reference speed provided by the speed controller. When the motor reaches a constant speed, the stator voltage and frequency decrease. The simulations also demonstrate the motor's response when accelerating from low to high speeds and vice versa. The study aims to analyze the induction motor's performance when powered by a PEM fuel cell for an electric vehicle.
Maglev trains use magnetic levitation to move along guideways without touching the ground. This reduces friction and allows for higher speeds. The fastest commercial train is the Shanghai Maglev, which reaches 430 km/h. Maglev trains move more smoothly than wheeled trains and are less affected by weather. While more expensive to build initially, maglev systems have lower maintenance costs than conventional trains. Only a few commercial maglev lines have been built, but many countries are researching the technology further.
The document discusses magnetic levitation (Maglev) trains. It begins by defining Maglev as using magnetic levitation to suspend, guide, and propel trains using magnets. It then explains the basic principles of levitation, propulsion, and lateral guidance that Maglev trains use to operate at high speeds. This includes using magnets to levitate the train 10 cm above the track and linear motors in the guideway to propel the train electromagnetically. The document also discusses the technologies, merits, and demographics of existing and planned Maglev systems around the world.
The document describes an All-Terrain Autonomous Vehicle (ATAV) designed and built for a class project. The ATAV uses a tank-style continuous track chassis powered by two motors controlled by an Arduino microcontroller. An ultrasonic sensor mounted on a servo detects obstacles and allows the ATAV to navigate around them to reach a target location. The ATAV was designed in phases, testing the drivetrain, integrating sensors, and adding localization functions to enable autonomous navigation between start and end points while avoiding obstacles. Testing showed the ATAV could successfully detect and maneuver around obstacles to reach its target location.
Maglev trains are the fastest trains in the world! Maglev is short for magnetic levitation which basic principles involve the use of magnetism to levitate an object.
EU-Cycle is a self balancing electric unicycle. A regular unicycle is powered by pedal and is balanced by a rider, whilst the EU-Cycle runs by an electric motor and balance by control system in the roll direction. The simple thing to do by rider is to lean forward for acceleration, to lean backward for braking. EU-Cycle is designed as to be a fast and portable means of transport among crowded area, home and office. Therefore, The EU-Cycle gives tough challenge to the unicycle. EU-Cycle has attracted print media including future stories in radio, television. Thus in addition to successful development of EU-Cycle in urban use, the project has to implement the EU-cycle as an educative device.
it is all about the working and little bit of history of the magnetic trains,
its a collection of knowledge,
find the references at end for more information
The document summarizes research on using chitosan to remove copper from wastewater. Chitosan is a biopolymer that can effectively sorb and remove copper. The study found that copper removal by chitosan increased with contact time until equilibrium was reached at 140 minutes. Copper removal also increased with increasing copper concentration and temperature, indicating the process is endothermic. Kinetic data showed the removal follows first-order kinetics. Thermodynamic calculations found the process is spontaneous with increasing temperature based on negative Gibbs free energy values and positive enthalpy changes. Copper uptake increased with increasing pH from 2 to 6.5. Overall, the research demonstrates chitosan is an effective and low-cost adsorb
This document summarizes methods for producing metal foams from aluminum alloys. It discusses direct foaming which injects gas into molten metal and indirect foaming using solid precursors. Direct foaming is commercially used but indirect foaming offers more control over pore structure. The document also outlines properties of aluminum foam including low density, stiffness, energy absorption and strength. Applications mentioned are lightweight construction, reinforcement of polymers, and use as cores in castings. Challenges remain in producing foams with uniform, controlled pore structures.
A Cost Estimation Model For Reuse Based Software ProgramIOSR Journals
This document presents a cost estimation model for a software reuse program. It proposes estimating costs at multiple levels - component, domain, application, and corporate. Costs include development, overhead, integration, and maintenance. The model is demonstrated using a hypothetical software company that develops reusable components from 2007-2010. Component size, availability, strategies, scale, standardization, and complexity are identified as factors that affect costs. Equations are provided to estimate costs at each level based on variables like component size, salary, reuse metrics, and probability of component availability. Graphs show relationships between various cost-affecting factors and total application costs.
This document examines using a Static Synchronous Compensator (STATCOM) for reactive power compensation in Nigeria's electricity grid. It develops power flow equations to model the grid's 28-bus, 330kV system with and without STATCOM. Simulations using MATLAB show that with STATCOM, voltage magnitudes at 5 buses rise to within limits of 0.95-1.05 p.u. and total system power loss reduces by 5.88% from 98.21MW to 92.44MW. The results indicate STATCOM can stabilize voltages and reduce losses in the Nigeria grid.
This document discusses various artificial intelligence techniques for robot path planning, including ant colony optimization. It provides background on particle swarm optimization, genetic algorithms, tabu search, simulated annealing, reactive search optimization, and ant colony algorithms. It then proposes a solution for robotic path planning that uses ant colony optimization. The proposed solution involves defining a source and destination point for the robot, moving it forward one step at a time while checking for obstacles, having it take three steps back if an obstacle is encountered, and applying ant colony optimization algorithms to help the robot find an optimal path to bypass obstacles and reach the destination point.
This document discusses optimizing the energy production of an autonomous photovoltaic (PV) system with a simple charge regulator. The study determines the optimal open circuit voltage range of the PV field for 12V and 24V storage systems. Mathematical models are developed for PV modules, storage batteries, and charge regulators. Simulation results show that a PV field's open circuit voltage between 16-23V optimizes energy production for a 12V system, and between 34-43V for a 24V system, under standard test conditions. The optimal voltage ensures the intersection point between the PV and battery voltage-current characteristics is near the PV module's maximum power point.
Study of Characteristics of Capacitors, Having Non-Traditional Conical Electr...IOSR Journals
This document discusses a study of the characteristics of capacitors with non-traditional conical electrode shapes, compared to traditional parallel plate capacitors. The study found that capacitors with conical electrodes exhibit non-linear exponential or polynomial relationships for capacitance, charge distribution, and current sharing along the electrodes. This is unlike parallel plate capacitors which show linear relationships. The non-uniform characteristics of conical electrode capacitors could enable applications like tuning non-linear inductive loads or use in series or shunt connections.
This document presents a fuzzy logic controller for load frequency control of a two-area interconnected power system. It begins with background on load frequency control and conventional controllers. It then describes modeling a two-area system and developing a fuzzy logic controller with membership functions and rules. Simulation results in MATLAB/Simulink show that the fuzzy controller provides better performance than a PID controller in terms of settling time, overshoot, undershoot and steady state error. The fuzzy controller reduces deviations in frequency and tie-line power for different load disturbances with fast response and minimal error.
The document describes a static stress analysis and normal mode analysis of the horizontal tail structure of an aircraft using analysis software. It discusses using carbon fiber composite material to replace aluminum alloy 2124 for constructing the horizontal tail to reduce weight. The analysis found that replacing the aluminum alloy with carbon fiber composite for the upper and lower skins resulted in a 54.73% reduction in the total structural weight of the horizontal tail. The normal mode analysis determined the resonance frequency of the horizontal tail was 0.981 Hz, showing it is safe as the aircraft's frequency is 10 Hz.
This document provides an overview of VSAT (Very Small Aperture Terminal) network technology. It describes the key components of a VSAT network including the outdoor and indoor units, hub station, and satellite. The outdoor unit includes the antenna, transceivers, and amplifiers while the indoor unit includes the multiplexer/demultiplexer, modem, and interfaces. VSAT networks can be configured in a star topology with all traffic routed through the central hub or in a mesh topology allowing direct terminal-to-terminal communication. Common applications of VSAT networks include corporate networks, broadcasting, and interactive data services between distributed sites.
The document describes a study that uses a hybrid particle swarm optimization-genetic algorithm (hPSO-GA) to optimize PID controller parameters for automatic generation control of a four-area interconnected power system. The hPSO-GA is applied to obtain optimal PID parameters for controlling frequency deviations and tie-line power deviations following a 1% load perturbation in any single area. Simulation results show the hPSO-GA approach provides better dynamic responses than using PSO or GA alone, with faster settling times, smaller overshoots and undershoots.
This document presents an adaptive steganography technique based on an enhanced cipher hiding method for secure data transfer. It combines cryptography and audio steganography. The secret message is first encrypted using a modified least significant bit algorithm and 2's complement operations. The encrypted data is then embedded into the least significant bits of an audio file. Keys are generated and sent with the stego audio to the receiver. The receiver uses the keys to extract the encrypted data from the audio and decrypt it back to the original message. The technique aims to provide better security for data transmission over unsecured networks by taking advantage of both cryptography and steganography.
A Comparative Study on Dyeing of Cotton and Silk Fabric Using Madder as a Nat...IOSR Journals
This document presents a study comparing the dyeing of cotton and silk fabrics with madder, a natural red dye. Various mordanting techniques were tested, including pre-mordanting, post-mordanting, and simultaneous mordanting with alum and copper sulfate. The dyed fabrics were evaluated based on color characteristics and colorfastness properties. The results showed that silk fabrics dyed darker shades than cotton and exhibited better colorfastness to washing and rubbing when mordanted. Mordanted silk samples showed deeper colors and greater wash fastness compared to mordanted cotton samples. While mordanting improved some properties, the dyed fabrics generally displayed poor perspiration fastness.
Comparison of Psychological Variables within different positions of players o...IOSR Journals
This document discusses a study that compared psychological variables (competition anxiety, achievement motivation, and self-concept) among different playing positions (front, middle, back) of junior state boys' badminton players in Manipur, India. Sixty players participated in a tournament and completed questionnaires measuring the psychological variables. Results found no significant differences in competition anxiety, achievement motivation, or self-concept between the different playing positions.
The document discusses optimizing surface roughness values in hard turning of AISI 52100 steel through experimentation using tribological (speed, feed, depth of cut) parameters. Experiments were conducted on a CNC lathe using cBN inserts to machine AISI 52100 steel hardened to 60 HRC. A Taguchi L9 orthogonal array was used as the experimental design to study the effects of cutting parameters on roughness. Regression analysis was performed to develop relationships between parameters and roughness to optimize values with 98.27% accuracy and 4.69% error.
Comparison of an Isolated bidirectional Dc-Dc converter with and without a Fl...IOSR Journals
This document compares an isolated bidirectional DC-DC converter with and without a flyback snubber through simulation and hardware implementation. It begins with an introduction to isolated bidirectional converters and the problem of voltage spikes caused by transformer leakage inductance. It then describes the operation and components of the converter both with and without a flyback snubber. Simulation results show that the flyback snubber reduces voltage spikes by 78-80% by clamping the voltage. Hardware results for boost mode operation with a flyback snubber are also presented and agree with simulation.
This document discusses enhancing the flight time of multirotors using solar energy. It proposes a circuit with a secondary battery system powered by a small solar panel. The secondary battery charges continuously from the solar panel and provides additional power to the main battery during flight. Calculations are shown for designing a hexacopter model using this dual battery system. It was estimated that the solar-powered system could increase flight time by 16-30% compared to using the main battery alone. A prototype was tested and found to increase flight time by 40% compared to the non-solar model. The system allows continuous charging without removing batteries from the frame, improving usability for long-distance flights.
This document discusses health, safety, and environmental hazards associated with shot blasting processes in foundries. It identifies several key hazards including aluminum dust emissions which can cause respiratory issues if inhaled, musculoskeletal problems from vibration, noise exposure leading to hearing loss, and potential for dust explosions. The document proposes methods for assessing and improving safety in shot blasting machines, such as installing dust collection systems, proper personal protective equipment, and maintenance of equipment.
This document proposes using an enhanced suffix tree approach to measure semantic similarity between multiple documents. It involves preprocessing documents by removing stop words, special characters, and converting to lowercase. Phrases are extracted and used to construct a suffix tree, where internal nodes represent phrases shared across documents. Term frequency-inverse document frequency (tf-idf) is used to calculate weights for internal nodes. Cosine, Dice, and Hellinger similarity measures are then applied to calculate pairwise similarities between documents based on the weighted internal nodes. The approach aims to efficiently and accurately measure semantic similarity between documents.
This document describes the design and analysis of an automatic stirrup making machine. Some key points:
1. The machine aims to automate the production of stirrups used in concrete beams and columns to reduce human labor and increase productivity.
2. It consists of components like a rectifier, motor, sprockets, and dies that rotate to bend rebar into the square shape of the stirrup.
3. Design calculations are shown for selecting transmission components like sprockets and chain to achieve the desired bending speed from the motor torque.
4. The machine is designed to continuously produce 200x200mm stirrups from 6-8mm rebar with low power consumption for use in construction sites
This document discusses research using Bayesian optimization to determine effective locomotion techniques for tensegrity robots. The researchers developed code to control vibrating motors on a tensegrity robot and track its movement. Bayesian optimization was used to attempt to find optimal vibration frequencies that produced fast, straight movement of the robot. Several frequency sets were found that resulted in rapid straight movement, but further investigation is needed to confirm Bayesian optimization is the best approach for tensegrity locomotion learning.
The document describes the development of a wall-climbing robot that uses a tracked wheel mechanism. Two tracked wheels with 24 suction pads each are used to allow continuous locomotion up a vertical surface at a maximum speed of 15m/min. Mechanical valves are used to control vacuum supply to the suction pads as the wheels rotate. Engineering analyses were conducted to determine the required suction force and tendency of vacuum pressure changes during operation. An optimization experiment was also performed to maximize vacuum pressure using Taguchi methodology.
This document describes the development of a wall-climbing robot that uses a tracked wheel mechanism. The robot is able to climb vertical surfaces at a speed of 15 meters per minute. It uses 24 suction pads attached to two tracked wheels to adhere to surfaces. Mechanical valves are used to control vacuum pressure to the suction pads as the wheels rotate, allowing continuous locomotion up walls. Engineering analyses were conducted to determine the required suction forces and how vacuum pressure changes as suction pads are attached and detached during climbing.
The document describes the development of a wall-climbing robot that uses a tracked wheel mechanism. Two tracked wheels with 24 suction pads each are used to allow continuous locomotion up a vertical surface at a maximum speed of 15m/min. Mechanical valves are used to control vacuum supply to the suction pads as the wheels rotate. Engineering analyses were conducted to determine the required suction force and tendency of vacuum pressure changes during operation. An optimization experiment was also performed to maximize vacuum pressure using Taguchi methodology.
This document describes the development of a wall-climbing robot that uses a tracked wheel mechanism. Key points:
- The robot uses two tracked wheels with 24 suction pads each that are activated sequentially as the wheels rotate, allowing continuous climbing motion at a speed of 15m/min.
- The mechanical design and functioning of the tracked wheel system are described, including the use of mechanical valves to control vacuum supply to the suction pads.
- An experiment is presented that uses Taguchi methodology to optimize vacuum pressure, a critical factor for suction force.
Design and Analysis of Articulated Inspection Arm of RobotIJTET Journal
Nowadays Robot play a vital role in all the activities in human life including industrial needs. There is a definite trend in the manufacture of robotic arms toward more dexterous devices, more degrees of-Freedom, and capabilities beyond the human arm. The ultimate objective is to save human lives in addition to increasing productivity and quality of high technology work environments. The objective of this project is to design, analysis of a Generic articulated robot Arm. This project deals with the modeling of a special class of single-link articulated inspection arms of robot. These arms consist of flexible massless structures having some masses concentrated at certain points of hollow sections at the beam. Some aspects of the articulated Robot that are anticipated as useful are its small cross section and its projected ability to change elevation and maneuver over obstacle require large joint torque to weight ratios for joint actuation. A knuckle joint actions actuation scheme is described and its implementation is detailed in this project. The parts of the (AIA) arm are analyzed for deflection and stress concentration under loading conditions in different angles.
IJERD (www.ijerd.com) International Journal of Engineering Research and Devel...IJERD Editor
This document summarizes research on the motion analysis of a band release system used in aerospace vehicles. Modal analysis was conducted on the band and wedge block to determine modal frequencies. Ten mode shapes were extracted. Motion analysis was then conducted in ADAMS software to analyze displacement, velocity, and acceleration of the wedge block and band after actuation of a pyro-thruster. Analytical methods were also used to calculate strain energy stored in the band and its conversion to kinetic energy upon release to understand system behavior. The goal was to assess whether a clean separation occurs between components after band release.
Design and Analysis of Mechanism for Dynamic Characterization of Power Transm...iosrjce
Power transmission systems are being widely used for transmission of power between two members.
Once a particular transmission system is realized it needs to be qualified before its course of application. As
part of this intended torque of the transmission systems needs to be measured and tested. Conventional means of
dynamic characterization of power transmission system has got the demerit of energy consumption to a greater
extent. Because of this more effort is to be put in terms of power for the sake of testing the intended system.
Great need exists for a system which consumes less or ideally no energy while performing test. This project
aims at evolution of a novel technique for evaluating the torque transmitting capability of power transmission
systems without consuming more energy. To start with all the subsystems of the proposed design will be
identified and each of them will be designed for getting their dimensions. Then these dimensional models will be
transformed to solid model of the assembled configuration using 3D CAD software. Functional load which will
be experienced by this design will be assessed and structural analysis will be carried out against these loads
using Finite Element Method (FEM) in commercial FEA software i.e. ANSYS
The document describes the design and analysis of a mechanism to dynamically characterize power transmission systems without consuming significant energy. It involves using an electro-mechanical clutch connected to a motor via pulleys of different sizes to measure the torque transmitting capability of a transmission system by gradually increasing the load torque until slip occurs. Structural analysis using FEA found the design to be safe with a factor of safety above the minimum required.
Feasibility Study and Design of Electromagnetic Suspension Systems: A ReviewIRJET Journal
This document summarizes a review of research on the feasibility and design of electromagnetic suspension systems. It begins by comparing different suspension system designs and reviewing existing active and semi-active electromagnetic suspension systems. These systems use electromagnetic motors or magnetorheological dampers to sense the road surface and actively control wheel movement. The document then analyzes the advantages and disadvantages of different control strategies and mathematical models used to model vehicle dynamics. It concludes by proposing a hybrid electromagnetic suspension design that attempts to address limitations of current designs.
This document discusses modal analysis of rotating structures using active magnetic bearings. It begins by introducing modal analysis and its importance for analyzing high-speed rotating machinery. It then describes the experimental setup which uses active magnetic bearings to both levitate and excite a test rotor. Natural frequencies and mode shapes are identified for the free-free rotor both with and without bearing stiffness. Introducing bearing stiffness is found to increase natural frequencies and introduce additional modes. The document concludes by explaining how the active magnetic bearings can be used to artificially excite the rotor to measure its frequency response functions and identify its dynamic characteristics.
Modeling and Control of a Spherical Rolling Robot Using Model Reference Adapt...IRJET Journal
The document describes modeling and control of a spherical rolling robot using model reference adaptive control (MRAC). It presents the mathematical model developed for the robot based on its nonholonomic constraints. MRAC is used to control the robot by adjusting controller parameters to minimize the error between the robot's actual output and the output of a reference model for ideal behavior. Simulation results show the proposed MRAC scheme eliminates steady state error and improves transient response without requiring knowledge of the robot's dynamic equations.
This document discusses active magnetic bearings (AMBs). It provides background on AMBs, explaining that they support rotating machinery without physical contact using electromagnetic forces controlled by sensors and electronics. The document then describes the basic components and working principles of AMB systems, including electromagnets, position sensors, and control systems that use feedback to maintain the rotor's position. It explains that AMBs offer benefits over traditional bearings like reduced friction, vibration, and maintenance needs. However, it notes that AMB systems are more complex and expensive to implement initially.
Stairs Detection Algorithm for Tri-Star Wheeled Robot and Experimental Valida...Premier Publishers
This paper presents two contributions in the development of stair detection algorithm for climbing robot. First, a new tri-star wheeled mechanism was developed to smoothly overcome the stairs. Second, the sensor-based algorithm was proposed for detection of stairs and switching states autonomously. Two motor driven ultrasonic sensors feed the posture information of the robot back to the controller to recognize the climbing environment. The validity of the proposed algorithm was demonstrated through experiments in realizing climbing environment. The experiments prove that the proposed algorithm can do rolling, ascending and descending on the staircase.
Research Inventy : International Journal of Engineering and Scienceresearchinventy
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
IRJET- Review on Rover with Rocker-Bogie Linkage Mounted with Ultrasonic Sens...IRJET Journal
This document describes a rover designed with a rocker-bogie linkage suspension system and equipped with an ultrasonic sensor and Bluetooth module powered by solar energy. The rocker-bogie system, inspired by NASA designs, allows the six-wheeled rover to traverse uneven terrain by keeping all wheels in contact with the ground. An Arduino board controls the motors and ultrasonic sensor for navigation via commands from a Bluetooth module. The goal is to create an affordable rover capable of moving across multiple terrains using an efficient suspension system.
Displacement mechanical amplifiers designed on poly-siliconIJECEIAES
Using Poly-Silicon, the implementation of novel Displacement-amplifying Compliant Mechanisms (DaCM), in two geometries of accelerometers, allows for remarkable improvements in their operation frequency and displacement sensitivity, with different proportions. Similar DaCM´s geometries were previously implemented by us with Silicon. In all mentioned cases, the geometries of DaCM´s are adjusted in order to use them with Conventional Capacitive Accelerometer (CCA) and Capacitive Accelerometer with Extended Beams (CAEB), which operate in-plane mode, (y-axis). It should be noted that CAEB shows improvements (95.33%) in displacement sensitivity compared to ACC. Simulations results, carried out using Ansys Workbench software, validate the system’s performance designed with Poly-Silicon. Finally, a comparison with the similar systems, previously designed with Silicon, is also carried out.
COMPARISON OF RESPONSE TO UNBALANCE OF OVERHUNG ROTOR SYSTEM FOR DIFFERENT SU...IAEME Publication
Rotor unbalance is most common fault found in the rotating machines. Methods
are adopted to analyze the position of unbalance and to bring its effect into acceptablelimit. Vibration analysis is the most common technique used to analyze the rotor
system. Research have been performed on rotor supported atboth ends, however lessstudy has been done for overhung rotor. In this paper the response of overhung rotoron isotropic support and anisotropic support subject tounbalance has been presented.and equations aresolved using MATLAB programming. The effect of unbalancehas been studied on thebode plot. Forward and Reverse whirl are observed through Campbell diagram andmode shapes are plotted.
This document summarizes research on ultrasonic motors. It discusses how ultrasonic motors can be miniaturized for use in medical devices and robots. The researchers designed three types of ultrasonic motors with decreasing size down to 4mm long and 1.6mm diameter. The motors use a hollow cylindrical stator with piezoelectric plates to generate elliptical motion from two orthogonal bending modes. Finite element analysis was used to optimize the design. The motors' performance was characterized using a transient method measuring speed and calculating torque of a loaded rotor.
Robust Control of a Spherical Mobile RobotIRJET Journal
This document summarizes a research paper about controlling a spherical mobile robot using sliding mode control. It begins with an abstract that describes the challenges of controlling spherical robots due to their underactuated systems. It then provides background on previous control methods for spherical robots. The document presents the kinematic model of a 2-DOF spherical robot and describes how sliding mode control can be used to provide robust control and path following for the robot. It provides the equations for the sliding mode controller design. Finally, it presents simulation results showing the robot following a desired trajectory with minimal tracking error using the sliding mode controller.
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
This document reviews the design of an energy-optimized wireless sensor node that encrypts data for transmission. It discusses how sensing schemes that group nodes into clusters and transmit aggregated data can reduce energy consumption compared to individual node transmissions. The proposed node design calculates the minimum transmission power needed based on received signal strength and uses a periodic sleep/wake cycle to optimize energy when not sensing or transmitting. It aims to encrypt data at both the node and network level to further optimize energy usage for wireless communication.
This document discusses group consumption modes. It analyzes factors that impact group consumption, including external environmental factors like technological developments enabling new forms of online and offline interactions, as well as internal motivational factors at both the group and individual level. The document then proposes that group consumption modes can be divided into four types based on two dimensions: vertical (group relationship intensity) and horizontal (consumption action period). These four types are instrument-oriented, information-oriented, enjoyment-oriented, and relationship-oriented consumption modes. Finally, the document notes that consumption modes are dynamic and can evolve over time.
The document summarizes a study of different microstrip patch antenna configurations with slotted ground planes. Three antenna designs were proposed and their performance evaluated through simulation: a conventional square patch, an elliptical patch, and a star-shaped patch. All antennas were mounted on an FR4 substrate. The effects of adding different slot patterns to the ground plane on resonance frequency, bandwidth, gain and efficiency were analyzed parametrically. Key findings were that reshaping the patch and adding slots increased bandwidth and shifted resonance frequency. The elliptical and star patches in particular performed better than the conventional design. Three antenna configurations were selected for fabrication and measurement based on the simulations: a conventional patch with a slot under the patch, an elliptical patch with slots
1) The document describes a study conducted to improve call drop rates in a GSM network through RF optimization.
2) Drive testing was performed before and after optimization using TEMS software to record network parameters like RxLevel, RxQuality, and events.
3) Analysis found call drops were occurring due to issues like handover failures between sectors, interference from adjacent channels, and overshooting due to antenna tilt.
4) Corrective actions taken included defining neighbors between sectors, adjusting frequencies to reduce interference, and lowering the mechanical tilt of an antenna.
5) Post-optimization drive testing showed improvements in RxLevel, RxQuality, and a reduction in dropped calls.
This document describes the design of an intelligent autonomous wheeled robot that uses RF transmission for communication. The robot has two modes - automatic mode where it can make its own decisions, and user control mode where a user can control it remotely. It is designed using a microcontroller and can perform tasks like object recognition using computer vision and color detection in MATLAB, as well as wall painting using pneumatic systems. The robot's movement is controlled by DC motors and it uses sensors like ultrasonic sensors and gas sensors to navigate autonomously. RF transmission allows communication between the robot and a remote control unit. The overall aim is to develop a low-cost robotic system for industrial applications like material handling.
This document reviews cryptography techniques to secure the Ad-hoc On-Demand Distance Vector (AODV) routing protocol in mobile ad-hoc networks. It discusses various types of attacks on AODV like impersonation, denial of service, eavesdropping, black hole attacks, wormhole attacks, and Sybil attacks. It then proposes using the RC6 cryptography algorithm to secure AODV by encrypting data packets and detecting and removing malicious nodes launching black hole attacks. Simulation results show that after applying RC6, the packet delivery ratio and throughput of AODV increase while delay decreases, improving the security and performance of the network under attack.
The document describes a proposed modification to the conventional Booth multiplier that aims to increase its speed by applying concepts from Vedic mathematics. Specifically, it utilizes the Urdhva Tiryakbhyam formula to generate all partial products concurrently rather than sequentially. The proposed 8x8 bit multiplier was coded in VHDL, simulated, and found to have a path delay 44.35% lower than a conventional Booth multiplier, demonstrating its potential for higher speed.
This document discusses image deblurring techniques. It begins by introducing image restoration and focusing on image deblurring. It then discusses challenges with image deblurring being an ill-posed problem. It reviews existing approaches to screen image deconvolution including estimating point spread functions and iteratively estimating blur kernels and sharp images. The document also discusses handling spatially variant blur and summarizes the relationship between the proposed method and previous work for different blur types. It proposes using color filters in the aperture to exploit parallax cues for segmentation and blur estimation. Finally, it proposes moving the image sensor circularly during exposure to prevent high frequency attenuation from motion blur.
This document describes modeling an adaptive controller for an aircraft roll control system using PID, fuzzy-PID, and genetic algorithm. It begins by introducing the aircraft roll control system and motivation for developing an adaptive controller to minimize errors from noisy analog sensor signals. It then provides the mathematical model of aircraft roll dynamics and describes modeling the real-time flight control system in MATLAB/Simulink. The document evaluates PID, fuzzy-PID, and PID-GA (genetic algorithm) controllers for aircraft roll control and finds that the PID-GA controller delivers the best performance.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
Monitoring and Managing Anomaly Detection on OpenShift.pdfTosin Akinosho
Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
1. Introduction to Anomaly Detection
- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
3. What is ArgoCD?
- Discover ArgoCD, a declarative, GitOps continuous delivery tool for Kubernetes, and its role in deploying applications on edge devices.
4. Deployment Using ArgoCD for Edge Devices
- Step-by-step guide on deploying anomaly detection models on edge devices using ArgoCD.
5. Introduction to Apache Kafka and S3
- Explore Apache Kafka for real-time data streaming and Amazon S3 for scalable storage solutions.
6. Viewing Kafka Messages in the Data Lake
- Learn how to view and analyze Kafka messages stored in a data lake for better insights.
7. What is Prometheus?
- Get to know Prometheus, an open-source monitoring and alerting toolkit, and its application in monitoring edge devices.
8. Monitoring Application Metrics with Prometheus
- Detailed instructions on setting up Prometheus to monitor the performance and health of your anomaly detection system.
9. What is Camel K?
- Introduction to Camel K, a lightweight integration framework built on Apache Camel, designed for Kubernetes.
10. Configuring Camel K Integrations for Data Pipelines
- Learn how to configure Camel K for seamless data pipeline integrations in your anomaly detection workflow.
11. What is a Jupyter Notebook?
- Overview of Jupyter Notebooks, an open-source web application for creating and sharing documents with live code, equations, visualizations, and narrative text.
12. Jupyter Notebooks with Code Examples
- Hands-on examples and code snippets in Jupyter Notebooks to help you implement and test anomaly detection models.
Ivanti’s Patch Tuesday breakdown goes beyond patching your applications and brings you the intelligence and guidance needed to prioritize where to focus your attention first. Catch early analysis on our Ivanti blog, then join industry expert Chris Goettl for the Patch Tuesday Webinar Event. There we’ll do a deep dive into each of the bulletins and give guidance on the risks associated with the newly-identified vulnerabilities.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
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1. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 12, Issue 4 Ver. II (Jul. - Aug. 2015), PP 62-73
www.iosrjournals.org
DOI: 10.9790/1684-12426273 www.iosrjournals.org 62 | Page
Experimental Determination of Dynamic Characteristics of a
Vibration-Driven Robot
Ivan A. Loukanov1
, Svetlin P. Stoyanov2
1
Department of Mechanical Engineering, University of Botswana, Botswana,
2
Department of Technical Mechanics, University of Ruse, Bulgaria
Abstract : This paper presents the experimental determination of dynamic characteristics of a vibration-driven
robot. The mechanical system consists of a shaker and a chassis. The latter is mounted on wheels furnished with
one-way bearings build into the wheels hubs. The robot is propelled by the resonance vibrations created by the
shaker’s rotating masses, which generate propulsive impulses transmitted to the chassis. The latter were
modified by the one-way bearings to unidirectional impulses thus creating a forward motion. By measuring and
analyzing the accelerations of free damped oscillations of the propulsion system, when the chassis is fixed, the
mechanical parameters such as spring constant, natural frequency and the damping factor were obtained.
Moreover the resonance vibrations created by the shaker and the forced oscillations imposed to the chassis
were recorded when the robot is moving unloaded. By employing the FFT tool box of the MATLAB software the
frequencies and the magnitudes of accelerations of the shaker, the chassis and their relative accelerations were
obtained. Lastly another series of tests were conducted when the robot is loaded by its towing force and
accelerations and the towing force were measured and analyzed by using the FFT analysis.
Keywords: Resonance vibrations, inertia propulsion, one-way bearing, spring system, linear damping.
I. Introduction
For many decades the Nuclear and Chemical industry, the Military and the Navy experienced
shortages of robots which could be employed for observing, measuring, repair of pipes, air ducts and narrow
channels, caves, as well as for discovery and destroying land and underwater mines, unexploded shells etc. The
vibration-driven robots are cheap to manufacture, easy to control and propel through different environments,
because of the simplicity of their design and operation capabilities. They require less power and develop strong
traction as their propulsion is achieved by means of resonance vibrations of a specially designed one-degree-of-
freedom excitation system [1, 2]. On the other hand the new propulsion systems prevents the robot from getting
trapped in obstacles or on soft surfaces under the wheels [3] because the propulsion is created by means of
internally provided impulses applied to the chassis, thus no-torques are acted upon the wheels as in
conventional vehicles. Recently many academics are undertaking research in the field of mobile robots making
an effort to invent new methods of propulsion based on friction forces, rotating masses or rectilinear moving
masses inside of the robot [4], or designing and studying jumping robots by using the motion of two internally
moving masses [5, 6], or employing the difference between static and kinetic friction [7, 8, 9], etc.
This study is dedicated to an experimental determination of dynamic (mechanical) parameters of a
vibration-driven robot propelled by forced vibrations of a specially arranged propulsion system acting in the
direction of referred motion. The anticipated direction of motion is achieved by using one-way bearings
(clutches) mounted into the wheels hubs. They allow rotation of the wheels in one direction and prevent rotation
in the opposite one. The accomplished motion has a pulsing nature and utilizes only less than 50% of the input
energy to the oscillating system. By testing the robot and identifying the parameters of the system we expect
improving the performance of the propulsion system and maximizing its efficiency.
Therefore the objective of this study is to measure and analyze the free damped and force oscillations
of the shaker and the chassis of a prototype robot in order to determine the unknown mechanical and dynamic
parameters of the propulsion system such as natural damped frequencies, equivalent spring stiffness,
logarithmic decrement, coefficient of viscous resistance, damping coefficient, frequencies, accelerations etc.
II. Materials and Method
The object of this study is the mobile wheeled robot illustrated in Fig. 1. It is intended for inspections
and observations of air ducts or any other restricted environments where human do not have a direct access.
Furthermore it may be used in a dangerous military, chemical or radiation sites, such as nuclear power stations,
chemical reactors etc. This is the same mobile robot vehicle investigated and primarily tested in the studies [1,
2]. A similar configuration of a mobile motor vehicle is proposed by Goncharevich [3] with some design
differences. However it has never been constructed or investigated so far. Apart of this the author is liable to
3. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 64 | Page
Table 1 Major technical specification of the portable LabQuest 2 data-log and measuring system
Processor 800 MHz
Communications Wi-Fi 802.11 b/g/n; Bluetooth Smart for WDSS and Go Wireless Temp.
Interface Resistive touch screen; Touch and stylus navigation for efficiency and precision.
Data Recording Speed: 100,000 sps (samples per second); Resolution: 12-bit; Built-in GPS, 3-axis acc.
Memory Imbedded: 200 MB; External: MicroSD, USB flash drive.
Ports 5 USB ports; flash & component ports; DC power jack; MicroSD/MMC; Audio In & Out
Accelerometers that
can be used
Power supply: 30 mA, 5 VDC; Scope: ±49 m/s2
(±25 g); Accuracy: ±0.5 m/s2
(±0.05 g); Frequency
range: 0–100 Hz; Resolution: 0.037 m/s²
III. Experimental study of the free damped oscillations of the robot propulsion system
To determine the dynamic parameters of the robot propulsion system (shaker), the chassis of the robot
was fixed to the ground. The corresponding mechanical model is shown in Fig. 4 with the three masses
involved, the equivalent spring stiffness k and the coefficient of viscous resistance b. At that point the spring
system of the shaker is subjected to initial deflection bigger than the maximum amplitude of the oscillating
system and released with zero initial velocity. At this time the excitation system begins free damped oscillations
with its natural frequency until they fully vanished. During the excitation of the shaker the signal measured by
the #2 accelerometer was continuously recorded until it disappeared. The experiments were repeated three times
and then the recorded signals were separately analyzed. The individual parameters of the propulsion system
were estimated by using the recorded signals such as amplitudes, periods, frequencies etc. and others were
calculated according to the well-known equations.
Fig. 4 presents the mechanical model used for measuring the free damped & forced oscillations of shaker; where
1 is the chassis (body1 of mass m1); 2 – shaker (body 2 of mass m2), 3 - two synchronously rotating masses - m3.
3.1 Mechano-mathematical model used in the free damped oscillations of the robot propulsion system
In this case we are considering the robot propulsion system as one-degree-of-freedom. The choice of
the mathematical model is disputable, but we choose as a first approximation the linear model, where the spring
force is proportional to its deflection and the resisting force is proportional to the velocity of oscillations, as
presented in Fig. 5 below. When free oscillations are investigated the chassis is fixed and the rotating masses are
non-rotating but participating in the free oscillations of the shaker.
Fig. 5 presents the mathematical model of the excitation system, of bodies 2 and 3, where m=m2+m3
The linear model is governed by the homogeneous ordinary differential equation of second order, written as:
0222 kxxcxm (1)
where: m=m2+m3 is the oscillating mass of the excitation system (shaker), including the mass of the rotating
eccentric masses m3 and the spring system.
We also introduce the ratios:
2
22
2
2
2
2
and2
,and
mknmb
dtdxxdtxdx (2)
4. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 65 | Page
which are the second and the first time derivatives of the displacement x2 with respect to time, b is the
coefficient of viscous resistance [N.s/m], k is the stiffness of the equivalent spring [N/m] and:
2
and2 mknmb
(3)
In (3), n=b/2m=δ.f, [rad/s] is the damping coefficient of the oscillating system and ω [rad/s] is the
angular frequency of the damped oscillations. The magnitude of the oscillating mass of the shaker is m =
(m2+m3) = 1.31 kg, where m2=1.19 kg and m3=0.12 kg. Also the equation of logarithmic decrement is employed
in calculating the damping coefficient n as per the known equation:
δ = (1/3) ln [(ai /ai+3)] (4)
3.2 Experimental investigation of the free damped oscillations of the robot propulsion system
Figs. 6 & 7 and Figs. 8 & 9 exemplify the recorded free damped oscillations of the excitation system
being the propulsion system of the robot. The system has total oscillating mass m=1.31 kg and is connected to
the chassis by means of 10 same size and same stiffness helical tension springs. All the experiments of free
damped oscillations were conducted at the same mechanical setup and the oscillations were generated by
shifting the system from equilibrium position to its maximum position and releasing it from rest. In this case the
eccentric masses m3 were stationary (not rotated) and oscillating together with the shaker (body2).
In this series of experiments, experiment #1 was unsuccessful because it was accompanied by a high frequency
ripple of unknown origin. So we will discuss and analyze the experiments #2, #3 and #4 only. Each of the
experiments was analyzed by using two reference points from the recorded signal. This approach allows getting
better accuracy when evaluating each record.
In the following figures the first reference points are shown in blue color and the second points in red
color. The corresponding values of the time and the accelerations are listed in Table 2. The time interval is used
to calculate the frequencies and the magnitudes of accelerations in order to calculate the logarithmic decrement -
δ. The value of the decrement is employed to calculate the damping coefficient of the oscillating system by
means of the frequencies of oscillations, also obtained from this experiment.
In Fig. 6 (exp. #2) and Fig. 8 (exp. #4) the reference points 3 and 6 were used for determining the
system parameters as shown. The respective time instances t3 and t6 and the associated accelerations a3 and a6
are illustrated in the graphs. Fig. 7 (exp. #3) indicates the related reference points 4 and 7, the time instances t4
and t7, as well as the corresponding accelerations of the free damped oscillations a4 and a6.
By using the magnitudes of the accelerations at a particular time instant corresponding to the respective
reference points shown in the above figures the system parameters were determined and listed in Table 2. The
measured and processed data are finally averaged for the three experiments of the oscillating system.
0 0.5 1 1.5 2 2.5 3
-20
-15
-10
-5
0
5
10
15
Experiment N3
t, s
a,m/s2
t4
Point 4
Point 7
t7
a4
a7
Fig. 7 exhibits free damped oscillations
recorded from experiment #3 where data
are taken from reference points 4 and 7
0 0.5 1 1.5 2 2.5 3
-20
-15
-10
-5
0
5
10
15
Experiment N2
t, s
a,m/s2
t3
Point 3
Point 6
t6
a3
a6
Fig. 6 gives details for the free damped
oscillations of experiment #2 where data
are taken from reference points 3 and 6
5. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 66 | Page
It should be mentioned ones again that the parameters obtained from experiment #2 are based upon
reference points 3 & 6 and that of experiment #3 upon reference points 4 & 7. Also the parameters found from
experiment #4 were evaluated twice by using the data drawn from reference points 3 & 6 and after that from
points 4 & 7 as shown in Fig. 8 and Fig. 9 respectively. The reason for this approach is to account for the fact
that the results may vary when different reference points are employed within the same record. This method
allows getting better accuracy and eliminates the variation of the period due to some non-linear effects not
accounted for by the linear model shown in Fig. 5. The same approach could be used for experiments #2 and #3,
but due to constrained space in the paper it is done for experiment # 4 only.
Table 2 Test results from experiments # 2, #3 and #4 for m = 1.31 kg (free damped oscillations)
Parameters of the oscillating system
Equations
and units
Values of parameters
Exp. #2
(p. 3-6)
Exp. #3
(p. 4-7)
Exp. #4
(p. 3-6)
Exp. #4
(p. 4-7)
Avg.
Initial reference point, #3 t3 [s] 0.969 / 1.593 / /
Final reference point, #6 t6 [s] 1.441 / 2.061 / /
Initial reference point #4 t4 [s] / 1.445 / 1.750 /
Final reference point, #7 t7 [s] / 1.911 / 2.210 /
Period of free undamped oscillations, T = (t6-t3)/3 [s] 0.157 / 0.156 / 0.155
Period of free undamped oscillations, T = (t7-t4)/3 [s] / 0.155 / 0.153
Frequency of the free damped oscillations f = [1/(t6-t3)]/3 [Hz] 6.356 / 6. 410 / 6.432
Frequency of the free damped oscillations f=[1/(t7-t4)]/3 [Hz] / 6.438 / 6.522
Acceleration corresponding to point #3 a3 [m/s2
] 8.307 / 9.815 / /
Acceleration corresponding to point #6 a6 [m/s2
] 2.028 / 3.325 / /
Acceleration corresponding to point #4 a4 [m/s2
] / 6.447 / 6.939 /
Acceleration corresponding to point #7 a7 [m/s2
] / 1.326 / 1.432 /
Circular frequency of the damped system p=2πf [s-1
] 39.936 40.450 40.277 40.977 40.41
Logarithmic decrement, Exp. #2 and #4
and Exp. #3 & #4
δ = (1/3).ln (a3/a6)
δ = (1/3).ln (a4/a7)
0.470 / 0.361 /
0.471
/ 0.527 / 0.526
Coefficient of damping n=δ.f [s-1
] 2.988 3.391 2.313 3.430 3.031
Coefficient of viscous resistance b=2mn [Ns/m] 7.679 8.715 5.944 8.815 7.788
Circular frequency of the damped system ω=√│(n2
- p2
)│[s-1
] 39.824 40.307 40.210 40.833 40.29
Natural frequency of the damped system fω = ω/(2π), [Hz] 6.338 6.415 6.400 6.499 6.413
Coefficient of equivalent stiffness k = m2.ω2
, [N/m] 2037.9 2087.7 2077.7 2142.6 2086
Fig. 9 shows details of the free damped
oscillations of experiment #4 where data
are taken from reference points 4 and 7
0 0.5 1 1.5 2 2.5 3
-20
-15
-10
-5
0
5
10
15
20
Experiment N4
t, s
a,m/s2
Point 4
Point 7
t7
a7
a4
t4
Fig. 8 shows details of the free damped
oscillations of experiment #4 where data
are taken from reference points 3 and 6
0 0.5 1 1.5 2 2.5 3
-20
-15
-10
-5
0
5
10
15
20
Experiment N4
t, s
a,m/s2
Point 3
Point 6a6
a3
t6
t3
6. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 67 | Page
3.3 Experimental investigation of forced vibrations of shaker when the chassis is fixed.
New series of experiments were conducted with the robot propulsion system shown in Fig. 4 where the
chassis, body1, is fixed to the ground and body2 (shaker) subjected to forced oscillations generated by the
rotating eccentric masses m3. This is achieved by controlling the speed of the DC motor by means of a speed
controller such that the single-degree-of-freedom oscillating system approaches the resonance along the
ascending branch of the resonance graph. As a result the amplitudes of displacement, velocities and
accelerations of body2 (shaker) attained maximum values. During this time the signal generated by the
accelerometer #2 was continuously recorded for four seconds and saved by the LabQuest 2 data log system.
After that it was analyzed with the Fast Furies Transform (FFT) tool box of the MATLAB software.
Fig. 10 shows the experimental setup used for the forced oscillations done with the robot propulsion
system. The differential equation governing the forced vibrations of the oscillating system is:
)sin(2
3222 tmkxxcxm (5)
where: m=m2+m3, is the shaker oscillating (propulsion) mass and ρ is the offset from the axis of rotation of the
unbalanced rotating masses, having total mass m3 = 0.12 kg.
Two experiments were conducted with the chassis (body1) being fixed to the ground while the propulsion
system (shaker) is running in close to resonance condition. It is always difficult to set the supplied voltage to the
motor of the same magnitude. For this reason most of the repeated experiments experience slightly different
magnitudes of accelerations and amplitudes of resonance oscillations.
Figs. 11 and 13 present the recorded force oscillations while Figs. 12 and 14 demonstrate the corresponding
spectrograms obtained from the FFT analysis for experiments #1 and #2 respectively. From the spectrogram in
Fig. 12 shows the frequency of relative oscillations and the amplitude of the acceleration of body2 with respect
to the fixed body1 are found to be frel = 12.82 Hz and arel = 11.53 m/s2
.
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
-20
-15
-10
-5
0
5
10
15
20
Experiment N1
t, s
a,m/s2
Fig. 11 illustrates the relative resonance
oscillations of body2 with respect to the
fixed body1 during Exp. # 1
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
Experiment N1
f, Hz
Am/s2
Fig. 12 exemplifies the spectrogram of the
relative resonance oscillations of body2 with
respect to the fixed body1
1
2
3
4
5
Fig. 10 illustrates the equipment used in the forced vibration test, where: 1 is the shaker (body 2); 2
- LabQuest 2 unit, 3 – the power supply unit, 4 - motor speed controller: 5 - accelerometer # 2
7. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 68 | Page
Likewise from the spectrogram in Fig. 14 similar to that in Fig. 12 the frequency of forced oscillations
and the amplitude of the accelerations of body2 relative to the fixed body1 are found to be frel = 12.82 Hz and
arel = 10.51 m/s2
respectively. The difference in the accelerations is owing to the different voltage set up
supplied to the motor, hence small differences result in the generated accelerations for the same resonance
frequency of the shaker. Obviously the frequencies are not affected by the voltage deviation supplied to the DC
motor, only the amplitudes of accelerations are sensitive to that. The reason is that at different locations on the
ascending portion of the resonance graph, the magnification changes significantly, hence the accelerations vary.
Table 3 Experimental data of forced oscillations of body 2 regarding the fixed body 1
Number of
experiment
Frequency,
f1=f2, [Hz]
Circular freq.
ω2, [rad/s]
Acceleration,
a2=A, [m/s2
]
Average acceleration,
A2avg =A=(a2,#1+a2,#2)/2, [m/s2
]
Exp. # 1
12.82 80.53
11.53
11.02
Exp. # 2 10.51
IV. Experimental investigation of forced vibrations of unloaded robot in motion.
Fig. 16 presents the frequency
spectrogram of body1 (chassis) obtained
from exp. #1 when the unloaded robot is
in motion, f1 = 8.24 Hz & a1=A1 = 15.07
m/s2
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
14
16
Experiment N1
f, Hz
A1
,m/s2
Fig. 15 illustrates the recorded signals of
forced oscillations of body1 (blue),
body2 (green) and the relative acc. (red)
between body1 and body2, from exp. #1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
-40
-30
-20
-10
0
10
20
30
40
50
Experiment N1
t, s
a,m/s2
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
Experiment N2
f, Hz
A,m/s2
Fig. 14 shows the spectrogram of the
relative oscillations of body2 with
respect to fixed body1 during Exp. # 2
Fig. 13 illustrates the relative resonance
oscillations of body 2 with respect to the
fixed body 1 during Exp. # 2
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
-20
-15
-10
-5
0
5
10
15
20
Experiment N2
t, s
a,m/s2
8. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 69 | Page
Two experiments were conducted with the unloaded robot in motion. The objective is to analyze the
interactions between the forced oscillations of body2 and that of body1 as well as their relative interactions. Fig.
15 shows the recorded oscillations from experiment #1 of body1 (blue), body2 (green) and the relative
oscillations between bodies 1 and 2 shown in red color. Obviously the accelerations are poly-harmonic because
of interactions between the bodies involved in the oscillating system. In this case the signals produced by the
accelerometers attached to body1 (blue) and body2 (green) was recorded along with the generated relative
oscillations (red). Next, these signals were analyzed with the FFT tool box of MATLAB software to produce the
above spectrograms. These are shown separately in Figs. 16, 17 and Fig. 18.
It is remarkable that all bodies in the system oscillate with the same resonance frequency f1 = f2 = f = 8.
24 Hz but instead the amplitudes of their accelerations are dissimilar due to the difference in the power supply to
the motor in each test. The relative amplitude of the acceleration appears to be approximately the sum of the
accelerations of body1, a1 and body2, a2, i.e. A≈A1 + A2 or a ≈ a1 + a2 =15.07+16.16=31.23 m/s2
≈31.02 m/s2
, or
having only 0.61% difference. The difference in amplitudes is negligibly small and therefore it is neglected. So
the determined amplitudes and frequencies are of good accuracy and may be used in the forthcoming theoretical
studies of the same system and will give us an insight about the theoretically predicted dynamic parameters.
Fig. 18 shows the spectrogram of the
relative motion of body2 relative to body1
from Exp. #1 of the unloaded moving
robot, f =8.24 Hz, a=A= 31.02 m/s2
0 5 10 15 20 25 30 35 40 45 50
0
5
10
15
20
25
30
35
Experiment N1
f, Hz
ARelative,m/s2
Fig. 17 displays the frequency
spectrogram of body2 (shaker) obtained
from Exp. #1 when the unloaded robot is
in motion, f2 = 8.24 Hz and a2=A2 = 16.16
m/s2
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
14
16
18
Experiment N1
f, Hz
A2
,m/s2
Fig. 20 shows the frequency spectrogram
of body1 (chassis) taken from Exp. #2
when the unloaded robot was in motion, f1
= 8.54 Hz and a1=A1 = 16.51 m/s2
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
14
16
18
Experiment N2
f, Hz
A1
,m/s2
Fig. 19 illustrates the recorded signals of
forced oscillations of body 1 (blue), body 2
(green) and the signal of relative (red)
acceleration between them from Exp. #2
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
-50
-40
-30
-20
-10
0
10
20
30
40
50
Experiment N2
t, s
a,m/s2
9. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 70 | Page
From experiment #2, the recorded accelerations of body 1 and body 2 and the relative accelerations are
presented in Fig. 19. The same colors codes were used in identifying the accelerations of the bodies as in Fig. 15
above. By analyzing the results of exp. #2 it was detected that the three accelerations have the same frequency f
= 8.54 Hz and the value of the relative acceleration is approximately the sum of the accelerations of the
respective bodies: namely A ≈ A1 + A2, or a ≈ a1 + a2 = 16.51 +18.86= 35.38 m/s2
≈ 35.14 m/s2
as seen in the
spectrogram of Fig. 22. The differences in test 1 and test 2 are 0.61% and 0.68% respectively, so these are too
small and may be neglected. The experimental data obtained from experiments #1 and #2 are listed in Table 4.
Table 4 Experimental results from forced oscillations of the moving unloaded robot – body1 and body2
Number of Experiment
#
Common frequency
f1 = f2 = f
[Hz]
Acceleration
of body 1
a1, [m/s2
]
Acceleration
of body 2
a2, [m/s2
]
Relative acceleration between
body 1 and body 2
arel=A, [m/s2
]
Exp. # 1 8.24 15.07 16.16 31.02
Exp. # 2 8.54 16.51 18.86 35.14
Avg. of #1 and #2 8.39 15.79 17.51 33.08
The difference in the accelerations in these experiments is because of the different voltage supply to the motor
for each setup leading to different values of the accelerations. As mentioned in section 3.3, it is difficult to set
the system to the same resonance, so small variations in the values of accelerations and frequencies are likely.
V. Experimental investigation of forced vibrations of the loaded robot in motion.
Five experiments were conducted as per the set up shown in Fig. 23. In all of them a load sell of ±10 N
is used to measure the towing force of the robot along with the accelerometers #1 and #2 measuring the
accelerations of body1 and body2 respectively. The load sell is connected to body1 by means of a rubber string
intended to damp (minimize) the fluctuations in the recorded force, although not fully succeeded.
Fig. 23 illustrates the experimental set up where: 1
– is body1; 2 – body2; 3 – accelerometers #1; 4 –
accelerometer #2; 5 – load sell; 6 – new power
supply & speed controller; 7 – LabQuest 2 unit.
2
4
6 7
3
5
1
0 0.5 1 1.5 2 2.5 3 3.5 4
-15
-10
-5
0
5
10
15
20
25
t, s
a1
,m/s2
Fig. 24 shows the pattern of acceleration of body1
Fig. 21 denotes the frequency
spectrogram of body2 (green) from
Exp. #2 when the robot is in motion,
so the frequency f2 = 8.54 Hz &
acceleration a2=A2 = 18.86 m/s2
0 5 10 15 20 25 30 35 40 45 50
0
2
4
6
8
10
12
14
16
18
20
Experiment N2
f, Hz
A2
,m/s2
Fig. 22 presents the spectrogram of
the relative acceleration of body2
about body1 taken from Exp. #2
while the robot is moving, then f =
8.54 Hz, and A = 35.14 m/s2
0 5 10 15 20 25 30 35 40 45 50
0
5
10
15
20
25
30
35
40
Experiment N2
f, Hz
ARelative,m/s2
10. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 71 | Page
The experiments are done on a PV dry and horizontal surface under ambient temperature of 25 0
C.
Owing to the limited space in the paper only the graphs of experiment # 1 are shown. The rest of the tests results
are listed in Table 5, where the values of the accelerations, frequencies and mean towing force are shown. For
comparison purposes in addition to these data the last row in Table 5 repeats the average data taken from Table
4 for the unloaded robot’s accelerations and frequencies of body1 and body2 respectively.
Table 5 Experimental data obtained from the loaded robot with its towing force and of unloaded robot
Fig. 29 shows the towing force F after being
modified (detrended) by the FFT analysis.
0 0.5 1 1.5 2 2.5 3 3.5 4
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
t, s
DetrendedF,N
Fig. 30 specifies the main amplitude of towing
force F with the rest of amplitudes being minor.
0 5 10 15 20 25 30 35 40 45 50
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Spectrum of the detrended F
f, Hz
AmplitudeofthedetrendedF,N
Fig. 27 identifies the main frequency of the
acceleration of body2 with the rest being negligible
0 10 20 30 40 50 60 70 80 90
0
5
10
15
f, Hz
a2
,m/s2
0 0.5 1 1.5 2 2.5 3 3.5 4
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
t, s
F,N
Fig. 28 illustrates the variation of the towing
force F during test #1 for duration of 4 seconds
Fig. 26 shows the pattern of acceleration of body2
0 0.5 1 1.5 2 2.5 3 3.5 4
-25
-20
-15
-10
-5
0
5
10
15
20
25
t, s
a2
,m/s2
Fig. 25 displays the spectrogram of
accelerations
of body1 subjected to forced oscillations
0 10 20 30 40 50 60 70 80 90
0
2
4
6
8
10
12
14
f, Hz
a1
,m/s2
11. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 72 | Page
No.
of exp.
Accelerations
of Body1,
m/s2
Accelerations
of Body2,
m/s2
Frequencies
of Body1
Hz
Frequencies
of Body2
Hz
Mean value of
towing force, F
N
Frequency
of detrended
force, Hz
No. 1
a1,1=12.5
a1,2=2.45
a1,3=0.93
a2=14.8
0
0
f1,1=10.7
f1,2=21.5
f1,3=32.0
f2=10.7
0
0
5.38
f1,1= 10.7
f1,2 = 5.53
f1,3 = 0.49
No. 2 a1,1=11.7
a1,2 = 2.12
a1,3 = 1.12
a2=15.3
0
0
f1,1=11.0
f1,2=21.7
f1,3=32.7
f2=11.0
0
0
4.99
f1,1 =11.0
f1,2 = 0.49
f1,3 = 21.7
No. 3 a1,1= 8.49
a1,2 = 2.72
a1,3 = 0.64
8.19
0
0
f1,1=10.3
f1,2=20.8
f1,3=31.0
10.3
0
0
5.42
f1,1=10.3
f1,2 = 0.49
f1,3 =20.8
No. 4 a1,1=11.6
a1,2= 2.39
a1,3= 1.07
10.4
0
0
f1,1=10.3
f1,2=20.5
f1,3=31.0
10.3
0
0
5.32
f1,1=10.3
f1,2 = 0.49
f1,3= 20.8
No. 5 a1,1=13.0
a1,2 = 2.05
a1,3 = 0.96
12.3
0
0
f1,1= 9.76
f1,2=19.3
f1,3=29.1
9.76
0
0
5.14
f1,1 = 9.76
f1,2 = 0.24
f1,3 =19.5
Avg. #(1 to 5) a1,1,avg=11.5 12.2 f1,1,avg=10.4 f2,avg=10.4 Favg=5.25 f1,1,avg =10.4
Avg. #(1 to 2) 15.8 17.5 8.4 8.4 Unloaded Robot
VI. Discussion
In this paper an experimental investigation of a vibration-driven wheeled robot is conducted, studied
and analyzed. The objective was to determine the dynamic (mechanical) characteristics of the robot propulsion
system with the aim of employing these data in an upcoming study dedicated to the optimization of the robot
system. The optimization technique will be based upon a Multicriteria parametric optimization method by using
the determined parameters of the robot propulsion system in this study as a pilot data. The experimental results
obtained from the free damped oscillation of the robot propulsion system (body2) were listed in Table 2. On the
other hand the data of forced oscillations of body2 relative to the fixed body1 are recorded in Table 3. It was
found that both bodies oscillate with the same forced frequency during the experiments but the magnitudes of
their accelerations differ because of the slight difference in the voltage set up to the motor during each
experiment. The latter forces the motor to operate with different speeds of rotation and hence dissimilar values
of the individual accelerations are registered.
Furthermore the robot mechanical system was investigated during forced resonance oscillations of the
propulsion system while the robot was moving with no towing force applied to it. The values of frequencies and
amplitudes of the respective accelerations of body1 (chassis) and body2 (shaker) were identified by employing
the FFT tool box of the MATLAB software. As a result the spectrograms showing the accelerations versus
frequency were constructed and the data obtained from them are listed in Table 4. It is found again that the two
bodies oscillate with the same frequency but have different accelerations, which relate to the difference in their
masses and ones again due to different voltage supplied to the motor. Incredibly, it was also found that the
relative acceleration between the shaker and the chassis appears to be the sum of the magnitudes of the
respective bodies’ accelerations, having about 0.61% to 0.68% difference. It was agreed to neglect that
difference which is considered small and compatible with the accuracy of the experimental equipment. Another
series of five experiments were conducted to investigate the accelerations and frequencies of the robot when it
was in motion but subjected to its maximum towing force. This is done by using a load cell attached to body1 as
shown in Fig. 23. The results of these experiments were listed in Table 5 and thoroughly analyzed to find out the
effect of the towing force on the accelerations and resonance frequencies developed by the propulsion system of
the robot when it is fully loaded. It is found that body1 and 2 oscillate with the same frequencies but have
slightly different accelerations ones again due to somewhat different power supply in each experiment.
It is also discovered that body1 has three significant frequencies with the lowest one being 10.74 Hz.
So the second significant frequencies of body1 is found to be twice the lowest one, mainly: f1,2=2× (f1,1=10.74)
= 21.48 Hz, and the third one is triple the lowest frequency, or f1,3 = 3× (f1,1=10.74) =31.98 Hz. Therefore these
frequencies appear to be multiple to the lowest frequency of body1. Finally the average frequency of body1 is
found to be 10.4 Hz and the same applies to the frequencies of body2, which average frequency was constant
equal to 10.4 Hz. Comparing the average accelerations and average frequencies of the moving robot without any
towing force acting on it and the loaded robot listed in Table 5, it is found that the accelerations of body1 and
body2 are 11.5 m/s2
and 12. 2 m/s2
respectively with their average frequencies being both equal to 10.4 Hz. On
the other hand for the loaded moving robot the respective average accelerations are 15.8 m/s2
and 17.5 m/s2
,
while their frequencies are the same but equal to 8.4 Hz. The analysis revealed that when the robot is loaded by
the towing force the accelerations of body1 and body2 increased by 37.4 % and 43.4% respectively, whiles the
average frequencies of their oscillations drop by 23.8%. These findings suggest that there is a significant
interaction between the oscillations of the bodies in the system and the components become more stressed when
the robot is loaded rather than when it is unloaded. Practically it means that there will be a possibility of
12. Experimental Determination of Dynamic Characteristics…
DOI: 10.9790/1684-12426273 www.iosrjournals.org 73 | Page
arranging the propulsion system in such a way so as to achieve and appropriate transmission of energy from
body2 to body1 and minimize the inertial loads. This could be set by selecting appropriate spring stiffness, mass
ratio and introduce an adequate damping in order to maximize the mean velocity of body1, increase the robot
displacement per cycle of oscillations and the take full advantage of the towing force.
VII. Conclusions
This paper presents the experimentally determined dynamic characteristics of a prototype wheeled
robot, which physical model is shown in Figs. 1, 2 and Fig. 4 along with the measuring and data-log system
illustrated in Fig. 3. The determined accelerations and frequencies of body1 and body2 are listed in Tables 2, 3,
4 and 5. They are of good accuracy due to the use of a sophisticated measuring and data-log system as well as
using the analyzing FFT tool box in the MATLAB software. The results will be used in a forthcoming study of
the same physical model of the robot as reference data and compared with the theoretically identified parameters
of the system. However, if a modified vibration-driven robot is investigated, it would require conducting similar
experimental study and analysis in order to obtain comparable parameters corresponding to the modified model.
To improve the towing ability and the mean velocity of the mobile robot it may be recommended to conduct an
optimization study and find out the influence of the individual dynamic parameters determined in this study
upon the robot mean velocity and the towing force. Obviously a Multicriteria parametric optimization would be
required as most of the determined parameters have significant influence upon the robot performance
characteristics. On the other hand to improve the efficiency of the robot propulsion system it would require
introducing another degree of freedom in the system. This eventually would have given the opportunity of
utilizing part of the rest 50% of the input energy so far lost during the return stroke in the one-way bearings. In
conclusions it may be stated that the experimental investigation described in this study provides important
values for the dynamic parameters of the prototype robot. They would ultimately be employed in further
optimization analysis to find out the optimum values of these parameters in order to maximize the mean velocity
and the towing force of the robot, combined with reduced inertial loads upon the components of the system.
Acknowledgments
This study was made possible thanks to the research Project FNI-RU, № 2015-МТF-01 funded by the
University of Ruse, Bulgaria. The authors are sincerely grateful to V.G. Vitliemov, I.V. Ivanov, S.G. Stoyanov
and V.S. Bozduganova from the department of Technical Mechanics for their continuous support and inspiration
during the project development. The authors also express their gratitude to Mr. E.G. Stanev for his assistance.
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