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.
This document describes the design of a passive ankle prosthesis that aims to mimic key aspects of the natural ankle. It is intended to provide energy return during walking that increases with walking velocity. The prosthesis uses a stiffening flexure mechanism to achieve non-linear rotational stiffness similar to the ankle. Testing shows the prototype averages 58.57% of the work of a natural ankle across different walking speeds and is capable of increasing energy return at higher walking velocities, similar to the biological ankle.
This document summarizes a student project investigating the effects of exercise on artificial hip joint prosthesis components through finite element analysis. The student modeled a Charnley-style femoral stem and acetabular cup under loads and angles associated with walking, jogging, and cycling. Simulation results showed that for high impact exercises, a stainless steel femoral stem and cobalt chromium acetabular cup prevented failure from excessive displacement and cracking. For low impact repetitive exercises, a titanium alloy femoral stem and ceramic acetabular cup prevented failure from excessive wear of the prosthesis.
Finite element stress analysis of artificial femur head on hip jointSAURABH SINGH
The increase of knowledge in all areas of research forms the premises for an increase in the life expectancy of the population as well as the quality of life, this increase of life expectancy are achieved through efficient medical care to meet the main objectives of improving and ensuring an adequate mobility for performing daily tasks.
Ik analysis for the hip simulator using the open sim simulatorEditorIJAERD
The model of the project to create a detailed assembly of muscles spotting the hip joint. Additional muscles
and combinations were added to the baseline lower extremity assemblies currently available in OpenSim. The geometry
of the muscles was adjusted to pair moment arms reported here. The slack moment and the isometric were added to the
arithmetic value of the tanquntial assembly of joints
This lecture discusses introductory mechanics models and constitutive models for biomaterials. The objectives are to establish biomaterial constitutive models, determine biomechanical response to load, analyze prosthetic design, and estimate health status of living tissues under stress. The lecture covers introductory mechanics modeling including stress analysis, normal and pure bending. Methods of biomechanics including analytical, experimental, and numerical techniques like FEM are presented. Constitutive models including elastic behavior, Hooke's law, elastic constants, material anisotropy, orthotropy, transverse isotropy, and isotropy are discussed.
An emg driven-musculoskeletal_model_to_esami bennour
This document describes the development and testing of an EMG-driven musculoskeletal model to estimate muscle forces and knee joint moments in vivo. The model uses EMG and joint kinematic data as inputs to estimate individual muscle forces and resulting knee joint moments. The model was calibrated for six individuals by adjusting physiological parameters to match net flexion/extension muscle moments measured through inverse dynamics. Once calibrated, the model predicted knee joint moments across over 200 dynamic tasks with high accuracy (average R2 of 0.91), demonstrating the model's ability to estimate muscle forces and joint moments over a wide range of dynamic conditions.
A Study on 3D Finite Element Analysis of Anterior Cruciate Ligament Behavior ...ijsrd.com
The present study deals with the force and stress distribution within the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) in response to an anterior tibial load with the knee at full extension was calculated using a validated three dimensional finite element model (FEM) of a human ACL. The interaction between the AM and PL bundles, as well as the contact and friction caused by the ACL wrapping around the bone during knee motion, were included in the model. The AM and PL bundles of the ACL were simulated as incompressible homogeneous and isotropic hyperelastic materials. The validated FEM was then used to calculate the force and stress distribution within the ACL under an anterior tibial load at full extension. The AM and PL bundles shared the force, and the stress distribution was non-uniform within both bundles with the highest stress localized near the femoral insertion site. The contact and friction caused by the ACL wrapping around the bone during knee motion played the role of transferring the force from the ACL to the bone, and had a direct effect on the force and stress distribution of the ACL. This validated model will enable the analysis of force and stress distribution in the ACL in response to more complex loading conditions and has the potential to help design improved surgical procedures following ACL injuries.
This document summarizes a study that performed a 3D finite element analysis of the human femur bone. The analysis used a 3D CAD model of the femur obtained from medical scans. The model was meshed and material properties were assigned to different bone tissues. Nonlinear analyses were conducted to simulate loads on the femur during normal activities. Results were compared to previous studies to validate the model. The study found that cancellous bone tissue reduces stresses in the femur, with its absence causing stresses almost double the amount.
This document describes the design of a passive ankle prosthesis that aims to mimic key aspects of the natural ankle. It is intended to provide energy return during walking that increases with walking velocity. The prosthesis uses a stiffening flexure mechanism to achieve non-linear rotational stiffness similar to the ankle. Testing shows the prototype averages 58.57% of the work of a natural ankle across different walking speeds and is capable of increasing energy return at higher walking velocities, similar to the biological ankle.
This document summarizes a student project investigating the effects of exercise on artificial hip joint prosthesis components through finite element analysis. The student modeled a Charnley-style femoral stem and acetabular cup under loads and angles associated with walking, jogging, and cycling. Simulation results showed that for high impact exercises, a stainless steel femoral stem and cobalt chromium acetabular cup prevented failure from excessive displacement and cracking. For low impact repetitive exercises, a titanium alloy femoral stem and ceramic acetabular cup prevented failure from excessive wear of the prosthesis.
Finite element stress analysis of artificial femur head on hip jointSAURABH SINGH
The increase of knowledge in all areas of research forms the premises for an increase in the life expectancy of the population as well as the quality of life, this increase of life expectancy are achieved through efficient medical care to meet the main objectives of improving and ensuring an adequate mobility for performing daily tasks.
Ik analysis for the hip simulator using the open sim simulatorEditorIJAERD
The model of the project to create a detailed assembly of muscles spotting the hip joint. Additional muscles
and combinations were added to the baseline lower extremity assemblies currently available in OpenSim. The geometry
of the muscles was adjusted to pair moment arms reported here. The slack moment and the isometric were added to the
arithmetic value of the tanquntial assembly of joints
This lecture discusses introductory mechanics models and constitutive models for biomaterials. The objectives are to establish biomaterial constitutive models, determine biomechanical response to load, analyze prosthetic design, and estimate health status of living tissues under stress. The lecture covers introductory mechanics modeling including stress analysis, normal and pure bending. Methods of biomechanics including analytical, experimental, and numerical techniques like FEM are presented. Constitutive models including elastic behavior, Hooke's law, elastic constants, material anisotropy, orthotropy, transverse isotropy, and isotropy are discussed.
An emg driven-musculoskeletal_model_to_esami bennour
This document describes the development and testing of an EMG-driven musculoskeletal model to estimate muscle forces and knee joint moments in vivo. The model uses EMG and joint kinematic data as inputs to estimate individual muscle forces and resulting knee joint moments. The model was calibrated for six individuals by adjusting physiological parameters to match net flexion/extension muscle moments measured through inverse dynamics. Once calibrated, the model predicted knee joint moments across over 200 dynamic tasks with high accuracy (average R2 of 0.91), demonstrating the model's ability to estimate muscle forces and joint moments over a wide range of dynamic conditions.
A Study on 3D Finite Element Analysis of Anterior Cruciate Ligament Behavior ...ijsrd.com
The present study deals with the force and stress distribution within the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) in response to an anterior tibial load with the knee at full extension was calculated using a validated three dimensional finite element model (FEM) of a human ACL. The interaction between the AM and PL bundles, as well as the contact and friction caused by the ACL wrapping around the bone during knee motion, were included in the model. The AM and PL bundles of the ACL were simulated as incompressible homogeneous and isotropic hyperelastic materials. The validated FEM was then used to calculate the force and stress distribution within the ACL under an anterior tibial load at full extension. The AM and PL bundles shared the force, and the stress distribution was non-uniform within both bundles with the highest stress localized near the femoral insertion site. The contact and friction caused by the ACL wrapping around the bone during knee motion played the role of transferring the force from the ACL to the bone, and had a direct effect on the force and stress distribution of the ACL. This validated model will enable the analysis of force and stress distribution in the ACL in response to more complex loading conditions and has the potential to help design improved surgical procedures following ACL injuries.
This document summarizes a study that performed a 3D finite element analysis of the human femur bone. The analysis used a 3D CAD model of the femur obtained from medical scans. The model was meshed and material properties were assigned to different bone tissues. Nonlinear analyses were conducted to simulate loads on the femur during normal activities. Results were compared to previous studies to validate the model. The study found that cancellous bone tissue reduces stresses in the femur, with its absence causing stresses almost double the amount.
The document discusses the application of computer aided engineering (CAE) techniques like finite element analysis to predict stress transfer in femurs after implantation of standard and short femoral stem hip implants. Specifically, it details:
1) Creating 3D CAD models of femurs from CT scan data and designing stem implants.
2) Reviewing forces on femurs during gait and applying them in finite element analysis models.
3) Analyzing the models to compare stress distributions between standard and short stem implants, finding the short stem allows a more physiological stress distribution.
4) Concluding CAE techniques like CAD and FEA can effectively examine implant designs before surgery and optimize factors affecting bone stress.
Prediction the Biodynamic Response of Seated Human Body to Vibration Using A...MOSTAFAABDEEN1970
The document describes an analytical 4-degree-of-freedom (DOF) biomechanical model and a numerical model using artificial neural networks (ANN) to predict the biodynamic response of a seated human body subjected to vertical whole-body vibration. The analytical model represents the human body as 4 rigid masses interconnected by springs and dampers. The numerical model uses ANN to simulate and predict responses for different masses and stiffnesses based on data from the analytical model, requiring less effort than solving the analytical model each time. Results from both models showed that increasing human body mass or stiffness increases the seat-to-head transmissibility, driving-point mechanical impedance, and apparent mass responses.
This document discusses an experiment comparing the use of control moment gyroscopes (CMGs) and thrusters for attitude control of small spacecraft. A testbed was developed using the MIT Synchronized Position Hold, Engage, Reorient Experimental Satellites (SPHERES) facility and miniature Honeybee Robotics CMGs. The experiment involved applying torques of equal magnitude but opposite direction using thruster pairs and the CMG pair and measuring the resulting angular rates. Preliminary experiments found that the CMGs were able to generate both smaller and larger torques than the thrusters alone, indicating their potential to improve control authority for small spacecraft.
This study investigated the impact forces on a solid-static prototype arm model at different elbow angles during a seated downward pole planting motion in sledge hockey. A 2D prototype arm was dropped from various heights with the elbow fixed at 120°, 135°, and 150° and impact forces were measured. The results showed that elbow angle affects impact reaction forces, with a 45° forearm angle producing the lowest impact forces and a flexed elbow between 120-150° producing the highest power generation. Understanding these baseline impact measures will help evaluate shoulder-loading in sledge hockey skills and identify angles that minimize injury risk while optimizing force production.
The document summarizes key aspects of human gait, including the gait cycle, phases of stance and swing, joint motions, muscle functions, shock absorption, energy conservation, and analysis methods. The gait cycle consists of stance and swing phases, with stance further divided into initial contact, loading response, mid stance, terminal stance, and preswing. Key motions include plantarflexion during loading response, dorsiflexion during single support, and plantarflexion at toe-off. Muscles like the quadriceps and hamstrings function to control knee motion and absorb shock during gait. Analysis methods examine motion, forces, electromyography, work, and energy expenditure to evaluate gait.
An Integrated Musculoskeletal-Finite-Element Model to Evaluate Effects of Loa...Chun Phoebe Xu
This study developed an integrated musculoskeletal and finite element modeling framework to evaluate the effects of load carriage on tibial biomechanics during walking. The framework included:
1. A musculoskeletal model driven by motion capture and ground reaction force data from a subject walking with different load carriage amounts. This was used to calculate time-varying joint reaction forces.
2. A finite element model of the tibia generated using mesh morphing and mapping techniques, along with spatially varying material properties derived from CT imaging of a reference subject.
3. Physiologically realistic loading conditions for the finite element model, defined by the joint reaction forces calculated in the musculoskeletal model.
The framework assessed how load carriage affected joint reaction forces, tib
Passenger seat is main part of vehicle which has direct effect on her/his convenience. Seat suspension can remove unwanted and harmful vibration if right parameters were selected. Each of human body organs has specific natural frequency. When vehicle vibration reaches to this natural frequency, resonance will occur, and this phenomenon is harmful in long term. Usually lumped models used to predict human body response to vibration. In this paper, via Kitazaki biodynamic model, the seat to head vibration transmissibility was minimized by artificial neural network method. By this method, the optimum spring constant, damper coefficient and mass values were found.
This document presents the methods for a project modeling human gait using forward and inverse dynamics. It describes creating a 3-body model of the leg consisting of thigh, shank, and foot segments. Kinematic data from Winter et al. will be used to calculate joint positions, velocities and accelerations over the gait cycle. Forward dynamics will be used to model joint torques and forces during gait. Inverse dynamics will then calculate internal joint forces and stresses will be analyzed through finite element analysis. The objectives are to model both a human leg and prosthetic leg, compare their kinematics, forces and validate the results with literature to better understand discrepancies between natural and prosthetic gait.
The document summarizes the analysis and optimization of steering components for a human-powered vehicle (HPV). It describes the goals of reducing component weights by 60-80% while maintaining a safety factor above 1.5. The methodology included understanding load paths, applying finite element analysis to evaluate stresses, and iteratively modifying designs. All components met safety factor goals except the steering plate, which fell just short at 1.46. The optimizations achieved weight reductions but did not fully meet all initial percentage targets.
Passenger seat is main part of vehicle which has direct effect on her/his convenience. Seat suspension can remove unwanted and harmful vibration if right parameters were selected. Each of human body organs has specific natural frequency. When vehicle vibration reaches to this natural frequency, resonance will occur, and this phenomenon is harmful in long term. Usually lumped models used to predict human body response to vibration. In this paper, via Kitazaki biodynamic model, the seat to head vibration transmissibility was minimized by artificial neural network method. By this method, the optimum spring constant, damper coefficient and mass values were found.
This study aimed to compare quadriceps muscle activation and perceived exertion during the leg press and Smith machine squat exercises. The researchers measured muscle activation via EMG and perceived exertion ratings in athletes performing each exercise across a range of loads. They developed predictive equations to determine equivalent loads between exercises that produce the same muscle activation and perceived exertion. The muscle activation equation was less accurate due to individual variability, while the perceived exertion equation was more accurate as it reflects the overall exertion of each exercise rather than specific muscles. These equations provide a new tool to convert loads between exercises over a training period.
Muscle Force Control of a Kinematically Redundant Bionic Arm with Real-Time P...toukaigi
This document proposes a new method for controlling a muscle-driven bionic arm that addresses four key challenges: 1) muscle coordination for an over-actuated system, 2) enforcing muscle force constraints, 3) decreasing muscular fatigue by evenly distributing muscle forces, and 4) adapting to modeling errors in real-time. The method models the arm dynamics considering joint and muscle accelerations to construct a set of linear equations with muscle activation as the unknown. A pseudoinverse solution provides initial muscle forces, while the null space is used to distribute forces evenly for anti-fatigue. An estimated model is also included to represent the real model and is updated based on errors to adapt to uncertainties. The method is tested on a bending-stretch
ANKLE MUSCLE SYNERGIES FOR SMOOTH PEDAL OPERATION UNDER VARIOUS LOWER-LIMB PO...csandit
This study investigated how ankle muscle activity varies with knee and ankle joint angles during pedal operation in different driving positions. Experiments measured electromyography of ankle muscles during acceleration and overtaking tasks. Results showed muscle activity levels increased as the driving position moved the knee into extension and ankle into plantar flexion. The ratio of biarticular gastrocnemius muscle activity varied depending on knee angle. Smooth pedal operation was achieved through appropriate variation in relative muscle activity based on lower limb posture and pedal angle.
Healy and harrison et al. 2014 drop jump emg gluteoFábio Lanferdini
The document summarizes a study that examined the effects of a unilateral gluteal activation protocol on single leg drop jump performance. The study found:
1) Significant differences in contact time, peak ground reaction force, and flight time between the baseline day and when the gluteal exercises were performed, but no difference between the exercise day and a third baseline day, suggesting the improvements were due to practice not the exercises.
2) Using a typical error analysis to examine individual responses, there was no discernible pattern of enhancement or fatigue for any participant from the gluteal exercises.
3) In conclusion, the gluteal activation protocol did not acutely improve single leg drop jump performance beyond potential learning effects
This study investigated hip muscle activation during common closed-chain rehabilitation exercises and running in runners. Electromyography was used to measure gluteus maximus and medius activation during a resisted hip external rotation exercise, single leg squat with trunk rotation, forward lunge with resisted abduction, and running. The forward lunge elicited the highest hip muscle activation, but activation was still substantially less than during running. While the exercises activated the hip muscles more than non-weight bearing exercises, there remains a disconnect between activation during exercises and running. Further research is needed to identify exercises that more closely mimic muscle demands during running.
This study investigated the preparation phase of the seated double poling cycle in sledge hockey through biomechanical analysis. A solid-static prototype representing an adult male was used with motion capture and force plates to measure kinematics and kinetics. Results showed peak impact forces occurred before 5 milliseconds post contact. Forces were greatest when preparation began slightly below the horizon. Data provides baseline measures to understand preparation phase importance and insights to improve sledge hockey performance and shoulder joint health.
This study aims to define gait for shoulder-produced locomotion using the double-poling technique from sledge hockey. A solid-static prototype mimicking the average male torso was used to determine baseline measures during the preparation phase. The prototype's trajectory and reaction forces supported that preparation initiation should begin slightly below the horizon to produce the greatest force. Results from sledge hockey players and able-bodied controls will be used to illustrate the complete seated gait cycle, including phases for static-start, start cycle, contact, and recovery. This evidence could improve training and rehabilitation for people who use their shoulders for mobility.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity
The document discusses the American National Standards Institute (ANSI) and the importance of standards and quality in business. ANSI helps develop American National Standards to help businesses improve efficiency, reduce costs and enhance quality. It also discusses the role of the International Organization for Standardization (ISO), which works to create global quality standards and certifies suppliers to ensure they meet quality standards. Adopting and implementing standards is important for businesses to compete internationally and satisfy customers.
Internal audits are required by ISO 9000:2000 standards to be conducted periodically and independently to verify that an organization's quality system meets the ISO requirements. Effective internal audits include planning the scope, developing checklists, performing audits of processes, recording observations, and issuing corrective actions if needed. Regular internal audits can help facilitate continuous improvement, identify failures in the system, and provide feedback to management.
The document discusses the application of computer aided engineering (CAE) techniques like finite element analysis to predict stress transfer in femurs after implantation of standard and short femoral stem hip implants. Specifically, it details:
1) Creating 3D CAD models of femurs from CT scan data and designing stem implants.
2) Reviewing forces on femurs during gait and applying them in finite element analysis models.
3) Analyzing the models to compare stress distributions between standard and short stem implants, finding the short stem allows a more physiological stress distribution.
4) Concluding CAE techniques like CAD and FEA can effectively examine implant designs before surgery and optimize factors affecting bone stress.
Prediction the Biodynamic Response of Seated Human Body to Vibration Using A...MOSTAFAABDEEN1970
The document describes an analytical 4-degree-of-freedom (DOF) biomechanical model and a numerical model using artificial neural networks (ANN) to predict the biodynamic response of a seated human body subjected to vertical whole-body vibration. The analytical model represents the human body as 4 rigid masses interconnected by springs and dampers. The numerical model uses ANN to simulate and predict responses for different masses and stiffnesses based on data from the analytical model, requiring less effort than solving the analytical model each time. Results from both models showed that increasing human body mass or stiffness increases the seat-to-head transmissibility, driving-point mechanical impedance, and apparent mass responses.
This document discusses an experiment comparing the use of control moment gyroscopes (CMGs) and thrusters for attitude control of small spacecraft. A testbed was developed using the MIT Synchronized Position Hold, Engage, Reorient Experimental Satellites (SPHERES) facility and miniature Honeybee Robotics CMGs. The experiment involved applying torques of equal magnitude but opposite direction using thruster pairs and the CMG pair and measuring the resulting angular rates. Preliminary experiments found that the CMGs were able to generate both smaller and larger torques than the thrusters alone, indicating their potential to improve control authority for small spacecraft.
This study investigated the impact forces on a solid-static prototype arm model at different elbow angles during a seated downward pole planting motion in sledge hockey. A 2D prototype arm was dropped from various heights with the elbow fixed at 120°, 135°, and 150° and impact forces were measured. The results showed that elbow angle affects impact reaction forces, with a 45° forearm angle producing the lowest impact forces and a flexed elbow between 120-150° producing the highest power generation. Understanding these baseline impact measures will help evaluate shoulder-loading in sledge hockey skills and identify angles that minimize injury risk while optimizing force production.
The document summarizes key aspects of human gait, including the gait cycle, phases of stance and swing, joint motions, muscle functions, shock absorption, energy conservation, and analysis methods. The gait cycle consists of stance and swing phases, with stance further divided into initial contact, loading response, mid stance, terminal stance, and preswing. Key motions include plantarflexion during loading response, dorsiflexion during single support, and plantarflexion at toe-off. Muscles like the quadriceps and hamstrings function to control knee motion and absorb shock during gait. Analysis methods examine motion, forces, electromyography, work, and energy expenditure to evaluate gait.
An Integrated Musculoskeletal-Finite-Element Model to Evaluate Effects of Loa...Chun Phoebe Xu
This study developed an integrated musculoskeletal and finite element modeling framework to evaluate the effects of load carriage on tibial biomechanics during walking. The framework included:
1. A musculoskeletal model driven by motion capture and ground reaction force data from a subject walking with different load carriage amounts. This was used to calculate time-varying joint reaction forces.
2. A finite element model of the tibia generated using mesh morphing and mapping techniques, along with spatially varying material properties derived from CT imaging of a reference subject.
3. Physiologically realistic loading conditions for the finite element model, defined by the joint reaction forces calculated in the musculoskeletal model.
The framework assessed how load carriage affected joint reaction forces, tib
Passenger seat is main part of vehicle which has direct effect on her/his convenience. Seat suspension can remove unwanted and harmful vibration if right parameters were selected. Each of human body organs has specific natural frequency. When vehicle vibration reaches to this natural frequency, resonance will occur, and this phenomenon is harmful in long term. Usually lumped models used to predict human body response to vibration. In this paper, via Kitazaki biodynamic model, the seat to head vibration transmissibility was minimized by artificial neural network method. By this method, the optimum spring constant, damper coefficient and mass values were found.
This document presents the methods for a project modeling human gait using forward and inverse dynamics. It describes creating a 3-body model of the leg consisting of thigh, shank, and foot segments. Kinematic data from Winter et al. will be used to calculate joint positions, velocities and accelerations over the gait cycle. Forward dynamics will be used to model joint torques and forces during gait. Inverse dynamics will then calculate internal joint forces and stresses will be analyzed through finite element analysis. The objectives are to model both a human leg and prosthetic leg, compare their kinematics, forces and validate the results with literature to better understand discrepancies between natural and prosthetic gait.
The document summarizes the analysis and optimization of steering components for a human-powered vehicle (HPV). It describes the goals of reducing component weights by 60-80% while maintaining a safety factor above 1.5. The methodology included understanding load paths, applying finite element analysis to evaluate stresses, and iteratively modifying designs. All components met safety factor goals except the steering plate, which fell just short at 1.46. The optimizations achieved weight reductions but did not fully meet all initial percentage targets.
Passenger seat is main part of vehicle which has direct effect on her/his convenience. Seat suspension can remove unwanted and harmful vibration if right parameters were selected. Each of human body organs has specific natural frequency. When vehicle vibration reaches to this natural frequency, resonance will occur, and this phenomenon is harmful in long term. Usually lumped models used to predict human body response to vibration. In this paper, via Kitazaki biodynamic model, the seat to head vibration transmissibility was minimized by artificial neural network method. By this method, the optimum spring constant, damper coefficient and mass values were found.
This study aimed to compare quadriceps muscle activation and perceived exertion during the leg press and Smith machine squat exercises. The researchers measured muscle activation via EMG and perceived exertion ratings in athletes performing each exercise across a range of loads. They developed predictive equations to determine equivalent loads between exercises that produce the same muscle activation and perceived exertion. The muscle activation equation was less accurate due to individual variability, while the perceived exertion equation was more accurate as it reflects the overall exertion of each exercise rather than specific muscles. These equations provide a new tool to convert loads between exercises over a training period.
Muscle Force Control of a Kinematically Redundant Bionic Arm with Real-Time P...toukaigi
This document proposes a new method for controlling a muscle-driven bionic arm that addresses four key challenges: 1) muscle coordination for an over-actuated system, 2) enforcing muscle force constraints, 3) decreasing muscular fatigue by evenly distributing muscle forces, and 4) adapting to modeling errors in real-time. The method models the arm dynamics considering joint and muscle accelerations to construct a set of linear equations with muscle activation as the unknown. A pseudoinverse solution provides initial muscle forces, while the null space is used to distribute forces evenly for anti-fatigue. An estimated model is also included to represent the real model and is updated based on errors to adapt to uncertainties. The method is tested on a bending-stretch
ANKLE MUSCLE SYNERGIES FOR SMOOTH PEDAL OPERATION UNDER VARIOUS LOWER-LIMB PO...csandit
This study investigated how ankle muscle activity varies with knee and ankle joint angles during pedal operation in different driving positions. Experiments measured electromyography of ankle muscles during acceleration and overtaking tasks. Results showed muscle activity levels increased as the driving position moved the knee into extension and ankle into plantar flexion. The ratio of biarticular gastrocnemius muscle activity varied depending on knee angle. Smooth pedal operation was achieved through appropriate variation in relative muscle activity based on lower limb posture and pedal angle.
Healy and harrison et al. 2014 drop jump emg gluteoFábio Lanferdini
The document summarizes a study that examined the effects of a unilateral gluteal activation protocol on single leg drop jump performance. The study found:
1) Significant differences in contact time, peak ground reaction force, and flight time between the baseline day and when the gluteal exercises were performed, but no difference between the exercise day and a third baseline day, suggesting the improvements were due to practice not the exercises.
2) Using a typical error analysis to examine individual responses, there was no discernible pattern of enhancement or fatigue for any participant from the gluteal exercises.
3) In conclusion, the gluteal activation protocol did not acutely improve single leg drop jump performance beyond potential learning effects
This study investigated hip muscle activation during common closed-chain rehabilitation exercises and running in runners. Electromyography was used to measure gluteus maximus and medius activation during a resisted hip external rotation exercise, single leg squat with trunk rotation, forward lunge with resisted abduction, and running. The forward lunge elicited the highest hip muscle activation, but activation was still substantially less than during running. While the exercises activated the hip muscles more than non-weight bearing exercises, there remains a disconnect between activation during exercises and running. Further research is needed to identify exercises that more closely mimic muscle demands during running.
This study investigated the preparation phase of the seated double poling cycle in sledge hockey through biomechanical analysis. A solid-static prototype representing an adult male was used with motion capture and force plates to measure kinematics and kinetics. Results showed peak impact forces occurred before 5 milliseconds post contact. Forces were greatest when preparation began slightly below the horizon. Data provides baseline measures to understand preparation phase importance and insights to improve sledge hockey performance and shoulder joint health.
This study aims to define gait for shoulder-produced locomotion using the double-poling technique from sledge hockey. A solid-static prototype mimicking the average male torso was used to determine baseline measures during the preparation phase. The prototype's trajectory and reaction forces supported that preparation initiation should begin slightly below the horizon to produce the greatest force. Results from sledge hockey players and able-bodied controls will be used to illustrate the complete seated gait cycle, including phases for static-start, start cycle, contact, and recovery. This evidence could improve training and rehabilitation for people who use their shoulders for mobility.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity
The document discusses the American National Standards Institute (ANSI) and the importance of standards and quality in business. ANSI helps develop American National Standards to help businesses improve efficiency, reduce costs and enhance quality. It also discusses the role of the International Organization for Standardization (ISO), which works to create global quality standards and certifies suppliers to ensure they meet quality standards. Adopting and implementing standards is important for businesses to compete internationally and satisfy customers.
Internal audits are required by ISO 9000:2000 standards to be conducted periodically and independently to verify that an organization's quality system meets the ISO requirements. Effective internal audits include planning the scope, developing checklists, performing audits of processes, recording observations, and issuing corrective actions if needed. Regular internal audits can help facilitate continuous improvement, identify failures in the system, and provide feedback to management.
The document provides an overview of general process modeling frameworks and approaches. It discusses theoretical, empirical and semi-empirical models. Theoretical models are derived from first principles like balances and property models, empirical models fit data to map inputs to outputs, and semi-empirical models use first principles and parameter fitting. It also describes types of process models like lumped vs distributed, steady state vs transient, and single vs multi-stage models. Key modeling concepts discussed include degrees of freedom, mass, energy and momentum balances, and modeling of flows, reactions and heat transfer.
The Malcolm Baldrige National Quality Assurance Awardahmad bassiouny
The document discusses the Malcolm Baldrige National Quality Award, which recognizes companies for excellence in quality. It was established in 1987 and named after Malcolm Baldrige, who championed quality management. Winning organizations are evaluated on their performance in seven key areas, including leadership, strategic planning, and business results. A board of volunteer examiners assesses applicants using rigorous criteria to select award winners each year.
The document outlines the aircraft design process from initial requirements definition through detailed design, testing, and certification. It discusses establishing basic and general requirements, conducting feasibility studies, specifying detailed requirements, conceptual and preliminary design phases involving configuration selection, performance modeling, and optimization. Later phases include detailed design, ground and flight testing, and certification to clear the aircraft for intended operations. The process is iterative with frequent trade-offs and refinement of requirements and design.
The document discusses various aspects of supplier quality management including supplier evaluation, certification, and control activities. It emphasizes establishing clear processes for evaluating suppliers prior to and after awarding contracts. Key aspects include reviewing suppliers' quality systems, production capabilities, performance history and metrics like yield and defects. Ongoing monitoring of suppliers involves activities like production audits, controlling changes, and ensuring suppliers meet requirements.
Dr jehad al sukhun gives modelling of orbital deformationjehadsukhun
The purpose of this study was to develop a three-dimensional finite-element model (FEM) of the human orbit, containing the globe, to predict orbital deformation in subjects following a blunt injury
Modelling of orbital deformation - Jehad Al Sukhun and othersDr Jehad Al Sukhun
The purpose of this study was to develop a three-dimensional finite-element model (FEM) of the human orbit, containing the globe, to predict orbital deformation in subjects following a blunt injury. This study investigated the hypothesis that such deformation could be modelled using finite-element techniques. To know more about modelling of orbital deformation contact to Jehad Al Sukhun at http://drjehadalsukhun.com.
Dynamic Model of Hip and Ankle Joints Loading during Working with a Motorized...J. Agricultural Machinery
The main objective of this paper is to develop a seven-link dynamic model of the operator’s body while working with a motorized backpack sprayer. This model includes the coordinates of the sprayer relative to the body, the rotational inertia of the sprayer, the muscle moments acting on the joints, and a kinematic coupling that keeps the body balanced between the two legs. The constraint functions were determined and the non-linear differential equations of motion were derived using Lagrangian equations. The results show that undesirable fluctuations in the ankle force are noticeable at the beginning and end of a swing phase. Therefore, injuries to the ankle joint are more likely due to vibrations. The effects of engine speed and sprayer mass on the hip and ankle joint forces were then investigated. It is found that the engine speed and sprayer mass have significant effects on the hip and ankle forces and can be used as effective control parameters. The results of the analysis also show that increasing the engine speed increases the frequency of the hip joint force. However, no significant effects on the frequency of the ankle joint force are observed. The results of this study may provide researchers with insight into estimating the allowable working hours with the motorized backpack sprayers, prosthesis design, and load calculations of hip implants in the future.
Static Aeroelasticity Analysis of Spinning Rocket for Divergence Speed -- Zeu...Abhishek Jain
Above Research Paper can be downloaded from www.zeusnumerix.com
The research paper aims to develop a method to model the spin effects of rocket for Aeroelastic analysis. As the speed of the rocket increases, the structural integrity of the fins becomes more dependent on aeroelastic loads. Methods exist to analyze aeroelasticity of fins for non-spinning missiles. Most software use panel methods for calculation of load distribution. The current research replaces the panel methods to RANS CFD and introduces source terms in equations to model spin. The results of new formulation are validated w.r.t. published data on non-spinning projectile and then the method is used to simulate current projectile. Mode shapes up to 6th mode are delivered as result. Authors - Sanjay Kumar and Prof GR Shevare (Zeus Numerix), Subhash Mukane and PT Rojatkar (ARDE, DRDO)
The Effect of Arm Stiffness on the Elasto-Kinematic Properties of Single-Axle...theijes
The paper is focused on the stiffness analysis of the longitudinal arm of single-axle suspension on elastokinematic behaviour of the vehicle axle which is highly important when considering the handling characteristics related tovehicle safety.The elasto-kinematic behaviour of the axle determines the course of the geometrical parameters of wheel suspension, the toe angle and camber as the function of wheel movement during force loading. This paper presents the complex MBS (Multi-Body Simulation)model of the wheel suspension with nonlinear characteristics of rubber-metal bushings. The model also comprises force elements such as springs, shock absorbers, stops and the transverse stabilizer. The model of flexible arm is implemented in the MBS model using the Craig-Bampton method, which represents a flexible body based on the synthesis of its own modal shapes. Subsequently,elasto-kinematic simulations are performed with the help ofthe computational system Hyperwork. The computational part of the paper presents the results of the elasto-kinematic behaviour of wheel axle for the flexible arm with different sheet metal thicknesses (2, 3 and 4 mm) and different materials (steel and aluminium alloy AlSi7Mg). Individual calculation models are compared to each other and also to the model of suspension with therigidarm. Elasto-kinematic analyses are also validated by the measurement inthe testing stage.
Determination of Flutter Angle by Resolving Effective Gyroscope Couple to Ret...IRJET Journal
The document discusses determining flutter angles for an airplane by resolving effective gyroscope couples. It presents a control algorithm that uses gyroscope measurements as inputs to predict flutter angles based on conditional statements. A Rayleigh-Ritz beam model and finite element model are developed to model the wing and wingtip fin. Flight tests show the robot can hover using feedback from either motion capture or gyroscope measurements of angular velocity, though position errors are larger when using full attitude estimates from the gyroscope due to drift in the pitch axis estimate.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The document summarizes various studies that have analyzed automobile frames using different techniques such as fatigue analysis, static analysis, and dynamic analysis. It discusses how finite element analysis has been used to study stress distributions in truck chassis, determine natural frequencies, and optimize chassis designs. Some key findings from studies discussed include that increasing chassis side member thickness can reduce stresses at joint areas, and mounting engine/transmission components along the first torsional vibration node reduces their effect. The document concludes that various analytical and experimental techniques are available for automobile frame analysis to determine stresses and durability under different operating conditions.
Prediction the Biodynamic Response of Seated Human Body to Vibration Using A...MOSTAFAABDEEN1970
The biodynamic response behaviors of seated human body subject to wholebody
vibration have been widely investigated. The biodynamic response
characteristics of seated human subjects have been extensively reported in
terms of apparent mass and driving-point mechanical impedance while seat-tohead
vibration transmissibility has been widely used to characterize response
behavior of the seated subjects exposed to vibration. These functions (apparent
mass, driving-point mechanical impedance) describe “to-the-body” force–motion
relationship at the human–seat interface, while the transmissibility function
describes “through-the-body” vibration transmission properties. The current study
proposed a 4-DOF analytic biomechanical model of the human body in a sitting
posture without backrest in vertical vibration direction to investigate the
biodynamic responses of different masses and stiffness. Following the analytical
approach, numerical technique developed in the present paper to facilitate and
rapid the analysis. The numerical analysis used here applies one of the artificial
intelligence technique to simulate and predict the response behaviors of seated
human body for different masses and stiffness without the need to go through the
analytic solution every time. The Artificial Neural Network (ANN) technique is
introduced in the current study to predict the response behaviors for different
masses and stiffness rather than those used in the analytic solution. The results
of the numerical study showed that the ANN method with less effort was very
efficiently capable of simulating and predicting the response behaviors of seated
human body subject to whole-body vibration.
Stress Analysis of Automotive Chassis with Various ThicknessesIOSR Journals
Abstract : This paper presents, stress analysis of a ladder type low loader truck chassis structure consisting of
C-beams design for application of 7.5 tonne was performed by using FEM. The commercial finite element
package CATIA version 5 was used for the solution of the problem. To reduce the expenses of the chassis of the
trucks, the chassis structure design should be changed or the thickness should be decreased. Also determination
of the stresses of a truck chassis before manufacturing is important due to the design improvement. In order to
achieve a reduction in the magnitude of stress at critical point of the chassis frame, side member thickness,
cross member thickness and position of cross member from rear end were varied. Numerical results showed that
if the thickness change is not possible, changing the position of cross member may be a good alternative.
Computed results are then compared to analytical calculation, where it is found that the maximum deflection
agrees well with theoretical approximation but varies on the magnitude aspect.
Keywords - Stress analysis, fatigue life prediction and finite element method etc.
The International Journal of a Mechanical Engineering Research and Technology is that an international online journal published Quarterly offers fast publication schedule whilst maintaining rigorous peer review. The use of recommended electronic formats for a article delivery expedites the process of All submitted research articles are subjected to the immediate rapid screening by editors consultation with Editorial Board or others working in the field of appropriate to ensure that they are likely to be the level of interest and importance of appropriate for the journal.
The International Journal of Mechanical Engineering Research and Technology is an international online journal in English published Quarterly offers a speed publication schedule with maintaining rigorous peer review and the use of recommended electronic formats of article delivery expedites the process of All submitted research articles are subjected to immediate rapid screening by the editors consultation with the Editorial Board or others working in the field of appropriate to ensure that they are similarly to be the level of interest and importance of appropriate for the journal.
This document summarizes a study that performed dual modeling and nonlinear optimization of two ceramic materials commonly used for ceramic-on-ceramic hip implants: alumina and zirconium. Numerical optimization results showed acceptable figures with low residuals. Two-dimensional graphical optimization also demonstrated acceptable results. The optimized model parameters were mathematically proven and verified. The results provide data that can inform future biomaterial designs for biomedical engineering applications.
This document discusses vibration suppression of a vehicle-bridge interaction system using multiple tuned mass dampers (TMDs). It presents a mathematical model of a system consisting of a vehicle, bridge beam, and three TMDs placed at different locations on the bridge. The model approximates the bridge deflection using the first four mode shapes. Equations of motion are derived for the vehicle, TMDs, and bridge using Lagrange's equations. It is found that placing TMDs at the anti-nodes of the first and second mode shapes is most effective for vibration suppression.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The document discusses design modifications and enhancements to the adaptability of mooring structures for medium-sized aerostats. It proposes three main modifications:
1) Mounting a bearing at the top of the mooring tower to eliminate twisting moments and reduce stresses.
2) Making the air bag frame adjustable to provide constant cushioned support to the balloon and keep it horizontal.
3) Fastening length pieces to allow the same structure to moor balloons of different sizes. Finite element analysis demonstrates that the modifications significantly reduce stresses on the structure.
Prediction the Biodynamic Response of the Seated Human Body using Artificial ...CSCJournals
The biodynamic response behaviors of seated human body subject to whole-body vibration have been widely investigated. The biodynamic response characteristics of seated human subjects have been extensively reported in terms of apparent mass and driving-point mechanical impedance while seat-to-head vibration transmissibility has been widely used to characterize response behavior of the seated subjects exposed to vibration. These functions (apparent mass, driving-point mechanical impedance) describe “to-the-body” force–motion relationship at the human–seat interface, while the transmissibility function describes “through-the-body” vibration transmission properties. The current study proposed a 4-DOF analytic biomechanical model of the human body in a sitting posture without backrest in vertical vibration direction to investigate the biodynamic responses of different masses and stiffness. Following the analytical approach, numerical technique developed in the present paper to facilitate and rapid the analysis. The numerical analysis used here applies one of the artificial intelligence technique to simulate and predict the response behaviors of seated human body for different masses and stiffness without the need to go through the analytic solution every time. The Artificial Neural Network (ANN) technique is introduced in the current study to predict the response behaviors for different masses and stiffness rather than those used in the analytic solution. The results of the numerical study showed that the ANN method with less effort was very efficiently capable of simulating and predicting the response behaviors of seated human body subject to whole-body vibration.
STATIC ANALYSIS OF A 6 - AXIS INDUSTRIAL ROBOT USING FINITE ELEMENT ANALYSISIAEME Publication
The present work aims to find out the Deformation, Stresses, Shear Elastic Strainand Strain Energy at different points of an industrial robot to determine it’s the safetyfactor by using Finite Element Method (FEM). Six axis industrial robots are generally
used in industries for various production works such as pick and place and fordifferent operations. So it needs to be properly designed. The model of robot isestablished using the ANSYS software and finite element analysis is done. Different
values of typical gripper loads are applied, and values at different conditions arecompared to find out the weak parts, so further design improvement can be done.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Experimental Investigation of a Household Refrigerator Using Evaporative-Cool...inventy
The objective of this paper was to investigate experimentally the effect of Evaporative-cooled condenser in a household refrigerator. The experiment was done using HCF134a as the refrigerant. The performance of the household refrigerator with air-cooled and Evaporative-cooled condenser was compared for different load conditions. The results indicate that the refrigerator performance had improved when evaporative-cooled condenser was used instead of air-cooled condenser on all load conditions. Evaporativecooled condenser reduced the energy consumption when compared with the air-cooled condenser. There was also an enhancement in coefficient of performance (COP) when evaporative-cooled condenser was used instead of air-cooled condenser. The Evaporative cooled heat exchanger was designed and the system was modified by retrofitting it, instead of the conventional air-cooled condenser by making drop wise condensation using water and forced circulation over the condenser. From the experimental analysis it is observed that the COP of evaporative cooled system increased by 13.44% compared to that of air cooled system. So the overall efficiency and refrigerating effect is increased. In minimum constructional, maintenance and running cost, the system is much useful for domestic purpose. This study also revealed that combining a evaporative cooled system along with conventional water cooled system under the condition that the defrost water obtained from the freezer is used for drop wise condensation over condenser and water cooled condensation of the condenser at the bottom using remaining defrost water would reduce the power consumption, work done and hence further increase in refrigerating effect of the system. The study has shown that such a system is technically feasible and economically viable
Copper Strip Corrossion Test in Various Aviation Fuelsinventy
This research work takes in to account of corrosiveness test on various aviation fuels in the state of Telengana (India). The purpose of this experiment is to determine the corrosiveness test of fuels. This determination will be accomplished by using copper strip corrosion test by using the copper strip experiment we can determine the corrosive property of the fuel and hence the efficiency of fuel. The research covers the importance of knowing the corrosive property of different petroleum fuels including aviation turbine fuel.
Additional Conservation Laws for Two-Velocity Hydrodynamics Equations with th...inventy
1) The document presents differential identities connecting velocities, pressure, and body force in two-velocity hydrodynamics equations where the pressure in each component is in equilibrium.
2) It summarizes previous work that derived conservation laws and differential equations for two-velocity hydrodynamic systems. Additional conservation laws are derived for these types of systems.
3) The key results are theorems that present differential identities relating the module and direction of a vector field. These identities can be considered additional conservation laws for two-velocity hydrodynamics equations with a single pressure.
Comparative Study of the Quality of Life, Quality of Work Life and Organisati...inventy
People’s lives are increasingly centred on work; they spend at least one-third of their time within the organisations that employ them. Investigating the factors that interfere with employees’ well-being and the organisational environment is becoming an increasing concern in organisations. This article identifies the criteria of the quality of life (QoL), quality of working life (QWL) and organisational climate instruments to point out their similarities. For bibliographic construction and data research, articles were sought in national and international journals, books and dissertations/articles in SciELO, Science Direct, Medline and Pub Med databases. The results show direct relationships amongst QoL, QWL and organisational climate instruments. The relationship between QoL and QWL instruments is based on fair compensation, social interaction, organisational communication, working conditions and functional capacity. QWL and organisational climate instruments are related through social interaction and interfaces. QoL and organisational climate instruments are related based on social interaction, organisational communication, and work conditions.
A Study of Automated Decision Making Systemsinventy
The decision making process of many operations are dependent on analysing very large data sets, previous decisions and their results. The information generated from the large data sets are used as an input for making decisions. Since the decisions to be taken in day to day operations are expanding, the time taken for manual decision making is also expanding. In order to reduce the time, cost and to increase the efficiency and accuracy, which are the most important things for customer satisfaction, many organisations are adopting the automated decision making systems. This paper is about the technologies used for automated decision making systems and the areas in which automated decisions systems works more efficiently and accurately.
Crystallization of L-Glutamic Acid: Mechanism of Heterogeneous β -Form Nuclea...inventy
The mechanism of heterogeneous nucleation of β-form L-glutamic acid was deeply investigated in cooling crystallization. The present study found that the β-form crystals were epitaxially grown on the α-form crystals and they were preferably crystallized on the (011) and (001) surfaces instead of the (111) surfaces of α- form crystals. This result was explained via the molecular simulation. The molecular simulation indicated that the different surfaces of α-form crystals provided different functional groups, resulting in different sites for the heterogeneous nucleation of β-form crystals. Here, the functional group were COO- , C=O and O-H on the (011) and (001) surfaces of α-form crystals, respectively, while it was the NH3 + on the (111) surfaces of α-form crystals. As such, the degree of lattice matching (E) between the β-form crystals and the various surfaces of α- form crystal was distinguished, where the degree of lattice matching (E) between the β-form crystals and the (011), (001) and (111) surfaces of α-form crystal were estimated as 5.30, 5.25 and 2.39, respectively, implying that the (011) and (001) surfaces of α-form crystal were more favorable to generate the heterogeneous nucleation of β-form crystals than the (111) surfaces of α-form crystal
Evaluation of Damage by the Reliability of the Traction Test on Polymer Test ...inventy
In recent decades, polymers have undergone a remarkable historical development and their use has been greatly imposed by gradually dethroning most of the secular materials. These polymer materials have always distinguished themselves by their simple shaping and inexpensive price, their versatility, lightness, and chemical stability but despite their massive use in everyday life as well as in advanced technologies. Generally, these materials still not understood which requires a thorough knowledge of their chemical, physical, rheological and mechanical properties. This paper, we study the mechanical behavior of an amorphous polymer: Acrylonitrile Butadiene Styrene “ABS” by means of uniaxial tensile testing on pierced test pieces with different notch lengths ranging between 1 to 14mm.The proposed approach consists in analyzing the evolution of the global geometry of the obtained strain curves by taking into account the zones and characteristic points of these curves as well as the effect of the damage on the mechanical behavior of the polymer ABS, in order to visualize the evolution of the damage by a static model
Application of Kennelly’model of Running Performances to Elite Endurance Runn...inventy
: The model of Kennelly between distance (Dlim) and exhaustion time (tlim) has been applied to the individual performances of 19 elite endurance runners (World-record holders and Olympic winners) from P. Nurmi (1920-1924) to M. Farah (2012) whose individual best performances on several different distances are known. Kennelly’s model (Dlim = k tlim ) can describe the individual performances of elite runners with a high accuracy (errors lower than 2 %). There is a linear relationship between parameters k and exponents of the elite runners and the extreme values correspond to S. Coe (k = 15.8; = 0.851) and E. Zatopek (k = 6.57; = 0.984). Exponent can be considered as a dimensionless index of aerobic endurance which is close to 1 in the best endurance runners. If it is assumed than maximal aerobic speed can be maintained 7 min in elite endurance runners, exponent is equal to the normalized critical speed (critical speed/maximal aerobic speed) computed from exhaustion times equal to 3 and 12.5 min in these runners.
Development and Application of a Failure Monitoring System by Using the Vibra...inventy
In this project, a failure monitoring system is developed by using the vibration and location information of balises in railway signaling. A lot of field equipment in railway are loosening and broken in time period so that they need maintenance due to the vibrations that occur due to high speed trains traffic and railway vehicles impact. Among the field equipment, balises have very important role of communication in terms of transmitting information to trains. In this scope, it is aimed to make maintenance works more efficient, have no delayed trains, detect previously failure location and intervene in failure timely, by detecting and controlling balise cases such as loosening, out of place and the data consistency error that happens because of balise physical state. In this project, the communication is provided with I2C, Modbus RTU (Remote Terminal Unit) and RS485 standards by using Arduino Uno cards and MPU6050 IMU (Inertial Measurement Unit) sensors in laboratory. Each used sensors are in slave mode and computer interface designed with C# is in master mode. Fault situations in the system are checked instant by the interface. (it is assumed to mount the IMU sensor and the Arduino circuit on the balise) it is seen that the interface responds to the sensor movements instant and the system works well in the end of test processes.
The Management of Protected Areas in Serengeti Ecosystem: A Case Study of Iko...inventy
This document summarizes a study that assessed the management of protected areas in Serengeti ecosystem, using Ikorongo and Grumeti Game Reserves as a case study. The study aimed to identify natural resource management strategies used, examine their impacts and hindrances, and identify ways to improve performance. It found that strategies have successfully reduced poaching by 96% and improved community relations. However, challenges remain like loss of life/property from wildlife conflicts and lack of access to water sources. The study concluded strategies have been fairly sustainable but need more participatory local approaches and benefit sharing to achieve collaborative management across the ecosystem. It recommended solutions like equitable benefit sharing, more funding, non-lethal deterrents, and strengthened
Size distribution and biometric relationships of little tunny Euthynnus allet...inventy
This study is taken from data of commercial fishing of the little tunny, Euthynnus alletteratus (Rafinesque, 1810) caught in the Algerian coast, sampled between november 2011 and april 2016. Data were collected in order to determine size distributions of the population and biometric relationships of species including the size - weight relationships. A total of 601 fish ranged from 30.9 and 103 cm fork length (FL) were observed. The size distribution of Euthynnus alletteratus shows multiple modal values witch the most important cohort corresponds to the age class 2 (42-46 cm). The value of the allometric coefficient (b) of the FL/TW relationship is lower than 3, indicating a negative allometric growth.
Removal of Chromium (VI) From Aqueous Solutions Using Discarded Solanum Tuber...inventy
Industrial polluting effluents containing heavy metals are of serious environmental concern in India. Chromium is frequently used in industries like electroplating, metal finishing, cooling towers, dyes, paints, anodizing and leather tanning and is found as traces in effluents finding their way to natural water bodies causing hazardous toxicity to the health of humans, animals and aquatic lives directly or indirectly. Many methods for the removal of Chromium such as chemical reduction, precipitation, ion exchange, electrochemical reduction, evaporation, reverse osmosis and adsorption using activated carbon etc. have been reported but all being expensive and complicated to operate. Experimental practices reveal that adsorption by agricultural and horticultural wastes are quite simple, inexpensive and efficient method. Agra is famous for Potato farming, a lot of discarded potato waste from cold storages is thrown along road side drains causing solid waste generated which either creates solid waste disposal problem or otherwise it finds way to Yamuna river resulting high BOD and posing a serious threat to the aquatic environment. For developing countries like India adsorption studies using discarded potato (Solanum tuberosum) waste from cold storages (DPWC) a solid waste as low cost adsorbent for Chromium removal was dual beneficial i.e., an ideal solution to these solid wastes disposal problem of Agra and removal of Chromium from tannery effluents and thereby saving aquatic life from Chromium contamination in Yamuna river. Keeping this in view batch experiments were designed to study the feasibility of discarded potato waste from cold storages to remove chromium (VI) from the aqueous solutions. During the study various affecting parameters, such as pH, adsorbent does, initial concentration, temperature, contact time, adsorbent grain size and start up agitation speed were optimized as 5.0, 10-20 g/l, 50 mg/l, 250C, 135 minutes, average size and 80 rpm respectively on chromium removal efficiency. Various Isotherms such as Langmuir, Freundlich, Tempkin also fitted suitably and various corresponding constants determined from these Isotherms favor and support the adsorption. Thermodynamic constants ∆G, ∆H and ∆S were found to be 0.267 KJ/mole, 0.288 KJ/mole and 0.0013 KJ/mole respectively.
Effect of Various External and Internal Factors on the Carrier Mobility in n-...inventy
The effect of various external (temperature, electric field, light) and intracrystalline (doping, initial resistivity) factors on the mobility of carriers in layered n-InSe semiconductor experimentally have been investigated. Scientific explanations of the results are proposed
Transient flow analysis for horizontal axial upper-wind turbineinventy
This study is to carry out a transient flow field analysis on the condition that the wind turbine is working to generate turbine, the wind turbine operating conditions change over time, Purpose of this study is try to find out the rule from the wind turbine changing over time . In transient analysis, the wind velocity on inlet boundary and rotation speed in the rotor field will change over time, and an analytical process is provided that can be used for future reference. At present, the wind turbine model is designed on the concept of upwind horizontal axis type. The computer engineering software GH Bladed is used to obtain the relationship between the rotor velocity and the wind turbine. Then the ANSYS engineering software is used to calculate the stress and strain distribution in the blades over time. From the analytical result, the relationship between the stress distribution in the blades and the rotor velocity is got to be used as a reference for future wind turbine structural optimization.
Choice of Numerical Integration Method for Wind Time History Analysis of Tall...inventy
Wind tunnel tests are being performed routinely around the world for designing tall buildings but the advent of powerful computational tools will make time-history analysis for wind more common in near future. As the duration of wind storms ranges from tens of minutes to hours while earthquake durations are typically less than a three to four minutes, the choice of a time step size (Δt) for wind studies needs to be much larger both to reduce the computational time and to save disk space. As the error in any numerical solution of the equation of motion is dependent on step size (Δt), careful investigations on the choice of numerical integration methods for wind analyses are necessary. From a wide variety of integration methods available, it was decided to investigate three methods that seem appropriate for 3D-time history analysis of tall buildings for wind. These are modal time history analysis, the Hilber-Hughes-Taylor (HHT) method or α-method with α=- 0.1, and the Newmark method with β=0.25 and γ=0.5 ( i.e., trapezoidal rule). SAP2000, a common structural analysis software tool, and a 64-story structure are used to conduct all the analyses in this paper. A boundary layer wind tunnel (BLWT) pressure time history measured at 120 locations around the building envelope of a similar structure is used for the analyses. Analyses performed with both the HHT and Newmark-method considering P-delta effects show that second order effects have a considerable impact on both displacement and acceleration response. This result shows that it is necessary to account P-delta effect for wind analysis of tall buildings. As the direct integration time history analysis required very large computation times and very large computer physical memory for a wind duration of hours, a modal analysis with reduced stiffness is considered as a good alternative. For that purpose, a non-linear static analysis of the structure with a load combination of 1.0D + 1.0L is performed in SAP2000 and the reduced stiffness of the structure after the analysis is used to conduct an eigenvalue analysis to extract the mode shapes and frequencies of this structure. Then the first 20- modes are used to perform a modal time history analysis for wind load. The result shows that the responses from modal analysis with “20-mode (reduced stiffness)” are comparable with that from the P-Δ analyses of Newmark-method
Impacts of Demand Side Management on System Reliability Evaluationinventy
This summary provides an overview of the impacts of demand side management (DSM) techniques on power system reliability in Saudi Arabia:
1. DSM techniques like load shifting can improve power system reliability by transferring load from peak to off-peak periods, reducing peak demand and allowing generators to operate more efficiently.
2. The study models load shifting and adding renewable energy sources to the Riyadh power system and calculates reliability indices like loss of load probability (LOLP) and expected energy not served (EENS) to analyze the impacts on reliability.
3. Preliminary results show load shifting can reduce peak demand and renewable energy from solar and wind can further contribute to reliability by providing generation during peak periods.
Reliability Evaluation of Riyadh System Incorporating Renewable Generationinventy
In this paper, the experience of Saudi Electricity Company (SEC) in analyzing the generation adequacy for Year 2013 is presented. This analysis is conducted by calculating several reliability indices for Riyadh system hourly load during all four seasonal periods. The reliability indices are gauged against the international utility practice. SEC also plans to introduce renewable energy into the network in order to secure the environmental standards and reduce fuel costs of conventional generation. Thus, the reliability improvement due to different integration levels of Solar and Wind generating sources has also been investigated. The capacity value provided by these variable renewable energy sources (VERs) to reliably meet the system load has been calculated using effective load carrying capability (ELCC) technique with a loss of load expectancy metric.
The effect of reduced pressure acetylene plasma treatment on physical charact...inventy
The capacitors are increasingly being used as energy storage devicesin various power systems. The scientists of the world are tryingto maximize the electrical capacity of the supercapacitors. To achieve this purpose, numerous method sare used: the surface activation of electrodes, the surface etching using the electronbeam, the electrode etching with variousgasplasma, etc. The purpose of this work is toresearch how the properties of carbon electrodes depend on the plasma parameters at whichtheywere formed. The largest surface area ofcarbonelectrodeof47.25m2 /gis obtainedat 15 ofAr/C2H2gasratio. Meanwhile, theSEMimages show that the disruption of structures with low bond energies and the formation of new onesare taking place when the carbon electrodes are etched at acetylene plasma and placed on carbon electrode. The measurements of capacitance showthat capacitors with affectedelectrodes have about10-15% highercapacity than those not treated with acetyleneplasma.
Experimental Investigation of Mini Cooler cum Freezerinventy
In general cases the refrigerator could be converted into an air conditioner by attaching a fan. Thus a cooler as well as freezer is obtained in a single set up. The freezer can be converted to an air conditioner when the outside air is allowed to flow beside the cooling coil and is forced outside by an exhaust fan. In this case a mini scale cooler cum freezer using R134a as refrigerant was fabricated and tested In our mini project work we had designed, fabricated and experimentally analysed a mini cooler cum freezer. From the observations and calculations, the results of mini cooler cum freezer are obtained and are compared.
Growth and Magnetic properties of MnGeP2 thin filmsinventy
We have successfully grown MnGeP2 thin films on GaAs (100) substrate. A ferromagnetic transition near 320 K has been observed by temperature dependent magnetization and resistance measurements. Field dependent magnetization experiments have shown that the coercive fields at 5, 250, and 300 K are 3870, 1380 and 155 Oe, respectively. Magnetoresistance and Hall measurements have displayed that hole conduction is dominant in MnGeP2. PACS: 75.50.Pp, 75.70.-i, 85.70.-w, 73.50.-h
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
Have you ever been confused by the myriad of choices offered by AWS for hosting a website or an API?
Lambda, Elastic Beanstalk, Lightsail, Amplify, S3 (and more!) can each host websites + APIs. But which one should we choose?
Which one is cheapest? Which one is fastest? Which one will scale to meet our needs?
Join me in this session as we dive into each AWS hosting service to determine which one is best for your scenario and explain why!
Ocean lotus Threat actors project by John Sitima 2024 (1).pptxSitimaJohn
Ocean Lotus cyber threat actors represent a sophisticated, persistent, and politically motivated group that poses a significant risk to organizations and individuals in the Southeast Asian region. Their continuous evolution and adaptability underscore the need for robust cybersecurity measures and international cooperation to identify and mitigate the threats posed by such advanced persistent threat groups.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
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G043055064
1. Research Inventy: International Journal Of Engineering And Science
Vol.4, Issue 3(March 2014), PP 55-64
Issn (e): 2278-4721, Issn (p):2319-6483, www.researchinventy.com
55
Lumped-parameter analytical methodology for evaluation of
adaptive seat damper to enhance rotorcraft crash safety
1,
Dr. Muthuvel Murugan, 2,
Dr. JinHyeong Yoo,
1, 2,
U.S. Army Research Laboratory – Vehicle Technology Directorate
4603 Flare Loop Drive, Aberdeen Proving Ground, MD 21005, USA.
ABSTRACT: This research study focuses on the analytical evaluation of magneto-rheological (MR)
dampers for enhanced occupant protection during vertical crash landings of a helicopter. The current state-of-
the-art helicopter crew seat has passive safety mechanisms that are highly limited in their capability to
optimally adapt to each type of crash scenario due to variations in both occupant weight and crash severity
level. While passive crash energy absorbers work well for a single design condition (50th
percentile male
occupant and fixed crash severity level), they do not offer adequate protection across a broad spectrum of
crash conditions by minimizing the load transmitted to the occupant. This study reports the development of a
lumped-parameter human body model including lower leg in a seated posture for rotorcraft crash injury
simulation. For implementing control, a control algorithm was made to work with the multi-body dynamic
model by running co-simulation. The injury criteria and tolerance levels for the biomechanical effects are
discussed for each of the identified vulnerable body regions, such as the thoracic lumbar loads for different
sized adults. The desired objective of this analytical model development is to develop a tool to study the
performance of adaptive semi-active magnetorheological seat suspensions for rotorcraft occupant protection.
KEYWORDS: Rotorcraft crash safety, seat energy absorber, magnetorheological energy absorber, crash
injury evaluation.
I. INTRODUCTION
Rotorcraft crew seats generally use passive energy absorbers to attenuate the vertical crash loads that
are transmitted through the fuselage structure of the rotorcraft to the seated occupant (Richards et al., 1997)
during a crash or hard impact landing event. These energy absorbers (EAs) include fixed-load energy absorbers
(FLEAs), shown in Figure 1 or variable load energy absorbers (VLEAs) (Richards et al., 1997; Desjardins et
al., 1989). These passive energy absorbing devices are not capable of automatically adapting their load-stroke
profile as a function of occupant weight or as a function of varying degree of impact severity during a crash or
hard landing event. In the recent times, smart adaptive energy absorbing devices, such as magneto-rheological
energy absorbers (MREAs), have emerged as an innovative solution for providing active crash protection by
utilizing a continuously adjustable profile EA in a controlled manner during a crash event. MREAs can adapt
their stroking load as a function of occupant weight and also can respond to various impact/shock excitation
levels in combination with a semi-active feedback controller. By intelligently adjusting the load-stroke profile
of the MREA as the seat strokes during a hard landing or crash event, MREAs have the capability of providing
an optimal combination of a short stroking distance coupled with minimal lumbar loads with varying occupant
weight and impact severity level. Furthermore, MREAs offer the unique ability to use the same seat suspension
system for both shock isolation during hard landings or crash impacts and for vibration isolation during
normal and extreme maneuvering flight conditions. This paper presents an analytical evaluation technique to
determine the performance benefits of MREA devices as compared to passive energy absorbers. This analysis
method can help to fine tune the design of these adaptive systems for different crash scenarios. This model will
also help in evaluating control algorithms that can be used in rotorcraft crashworthy seat systems. In this study,
a lumped-parameter human body model including lower leg in seated posture was developed for crash injury
assessment simulation. Typical rotorcraft crash pulse, as recommended by rotorcraft crashworthiness
requirements was used to assess crash injuries in different segments of the body of the seated occupant. The
injury criteria and tolerance levels for the biomechanical effects are discussed for each of the identified
vulnerable body regions.
2. Lumped-Parameter Analytical Methodology For Evaluation Of…
56
Figure 1. Fixed-load energy absorber (FLEA) utilized in SH-60 Seahawk crew seat (Hiemenz, 2007)
Nomenclature
AATD Army Aviation Applied Technology Directorate
DPM IM Driving-Point-Mechanical Impedance
EA Energy absorber
F, L Force or Load
FLEA Fixed-load energy absorber
IARV Injury Assessment Reference Value
MREA Magneto-rheological energy absorber
STH TR Seat-To-Head Transmissibility
VLEA Variable load energy absorber
c damping
g, G gravitational acceleration
k stiffness
m mass
ms milliseconds
t Time
Model Development
Seated Human Model
Consider a human sitting upright in a rotorcraft crew seat. A variety of mathematical models have been
proposed to describe the human body‟s response to vertical disturbances. In this study, Boileau‟s model
(Boileau et al., 1998) is used as a basic parameter model. However, Boileau‟s model was developed for
“average” passenger comfort evaluation and it has no lower leg consideration which may be important for
overall human body kinematics under extreme environment. To resolve this problem, the body segment mass
was extracted from anthropometric specifications for dummy family (Herman, 2007) for the 5th
percentile
female (small female), 50th
percentile male (average male), and 95th
percentile male (large male). The proposed
lumped parameter human body model, shown in Figure 2, comprises six masses for the respective six body
segments, coupled by linear/nonlinear elastic and damping elements. The six masses represent the following
six body segments: the head and neck (m1); the thorax (m2); the abdomen (m3); the pelvis (m4); the thighs (m5);
and the calf and foot (m6). The estimated body segment mass properties are summarized in Table 1. The hand
and arm masses (upper extremity) are not incorporated in the model assuming its negligible contributions to
the whole-body biodynamic response. The stiffness and damping properties of the cervical spine are
represented by k1 and c1, those of the thoracic spine by k2 and c2, those of the lumbar spine by k3 and c3, while
those of the buttocks and thighs on a seat by k4 and c4 as shown in Figure 2. Also, there are two torsion stiffness
and damping parameters for hip (k5, c5) and knee (k6, c6) joints (Ciarlet, 2004). The cited reference (Manseau
et al., 2005) reported that the military boot has a significant effect on the complex lower leg injury severity. To
take into account this boot effect, stiffness and damping parameters (kb and cb) were also implemented in the
model as shown in Figure 2. These stiffness and damping parameters (Cikajlo et al., 2007) are summarized in
Table 2 with the source of the data. Overall, this multi-body human model was developed at the U.S. Army
Research Laboratory primarily for vertical impact injury assessment simulations in vehicular extreme
environment scenarios such as crash or mine blast (Yoo et al., 2012).
3. Lumped-Parameter Analytical Methodology For Evaluation Of…
57
Figure 2. Lumped-parameter human body model
Table 1. Estimated segment mass and inertial properties (Herman, 2007)
Body segment
Small (5th
%ile)
Female
Medium
(50th
%ile)
Male
Large
(95th
%ile)
Male
Mass[kg] Mass[kg] Mass[kg]
Head (m1) 4.30 5.10 5.68
Thorax (m2) 17.50 28.79 37.90
Abdomen (m3) 1.61 2.37 2.95
Pelvis (m4) 6.98 11.41 16.04
Thigh (m5) 11.83 17.23 21.65
Calf & foot (m6) 6.00 11.66 18.24
Total 48.22 76.56 102.46
Table 2. Stiffness and damping coefficients of the human body segments
Stiffness Damping source
Cervical
spine (k1,
c1)
310.0[kN/m] 400.0[N·s/m]
(Boilea
u et al.,
1998)
Thoracic
spine (k2,
c2)
183.0[kN/m] 4750.0[N·s/m]
Lumbar
spine (k3,
c3)
162.8[kN/m] 4585.0[N·s/m]
Buttocks
(k4, c4)
90.0[kN/m] 2064.0[N·s/m]
Hip joint
(k5, c5)
Extension [N·m/rad]: 68.8
Flexion [N·m/rad]:
53.2·Exp(0.98×)-53.2
100.0
[N·m·s/rad]
(Ciarlet,
2004)Knee
joint (k6,
c6)
Extension [N·m/rad]:
90.5·Exp(2.0×
Flexion [N·m/rad]:
95.0·Exp(4.32×)-95.0
500.0
[N·m·s/rad]
Boot (kb,
cb)
300.47 [kN/m] 200.0 [N·s/m]
(Cikajlo
et al.,
2007)
The conceptual model of the rotorcraft floor structure with a crew seat used in this study is shown in
Figure 3. The point „A‟ in Figure 3 shows the coupling between the seat-occupant model and the rotorcraft
floor structure.
4. Lumped-Parameter Analytical Methodology For Evaluation Of…
58
Figure 3. Coupling between rotorcraft floor structure and seat-occupant model
Biodynamic Evaluation of Seated Human Model
The biodynamic responses of a seated human subjected to vertical vibration or shock exposure have widely
been assessed in terms of seat-to-head (STH) transmissibility, and driving-point mechanical (DPM) impedance
(Liang et al., 2006). To evaluate these performance indices, the whole human body model, shown in Figure 2,
was implemented in the multi-body dynamic simulation software, MSC/ADAMS and each segment responses
were simulated using the Vibration module in the software. The frequency step and frequency range of 0.5 Hz,
and up to 100 Hz were selected, respectively.
STH transmissibility (TR)
This function, STH transmissibility (TR) is defined as the ratio of output head response to input seat
excitation. It can be defined by the acceleration or displacement ratio. Therefore, TR can be expressed
according to the above derivation as shown in the cited reference (Liang et al., 2006):
)(
)(1
A
Z
jZ
TR (1)
where is frequency, ZA() is input displacement amplitude from seat, and Z1(j) is output displacement
amplitude from head and neck m1. Figure 4 presents a comparison of the transmissibility magnitude
characteristics calculated from the model with the mean and envelope of the experimental data from the cited
reference (Boileau et al., 1998).
DPM impedance (IM)
This function, DPM impedance is defined as the ratio of driving force between pelvis and seat to the input
velocity of the seat. Accordingly, IM (impedance) can be represented as follows (Liang et al., 2006):
)(
)]()()[( 444
A
A
Zj
jZZcjk
IM
(2)
where is frequency, ZA() is input displacement amplitude from seat, and Z4(j) is output displacement
amplitude from pelvis m4. Figure 5 presents a comparison of the impedance magnitude characteristics
calculated from the model with the mean and envelope of the experimental data from the reference (Boileau et
al., 1998).
1 10 100
Frequency [Hz]
0
0.4
0.8
1.2
1.6
2
SeattoHeadTR
Experiment [4]
Large Male
Small Female
5. Lumped-Parameter Analytical Methodology For Evaluation Of…
59
Figure 4. Comparison of the vertical seat-to-head vibration transmissibility characteristics computed from the
proposed human body model with those upper and lower limits of experimental data from (Boileau et al.,
1998)
1 10 100
Frequency [Hz]
0
1000
2000
3000
4000
Impedence[Ns/m]
Experiment [4]
Large Male
Small Female
Figure 5. Comparison of the vertical driving-point mechanical impedance characteristics computed from the
proposed human body model with those upper and lower limits of experimental data from (Boileau et al.,
1998)
Control algorithm development
For vibration isolation of seat damper, high damping will suppress the amplitude response, but worsen
the vibration transmissibility. Low damping will improve the transmissibility, but the relative displacement
between the seat and floor may be large enough to cause end-stop impacts especially for high shock input from
crash event. If the shock input force does not cause the suspension mechanism to hit the end-stop buffers, a
lower suspension damping may provide greater vibration isolation performance. However, for the input force
from crash event, an adjustable damper, which can be switched manually or automatically between a high
damping and low damping according to the passenger‟s weight or damper deflection, might be used. If the
damper is generally set to soft mode so as to provide low transmissibility, and adjust to the hard mode only
when end-stop impacts are likely to occur, the optimum performance might be achieved (Wu et al., 1997). End-
stop impacts will occur whenever the relative displacement between the seat and floor exceeds certain value. If
the damper is switched on whenever the relative displacement exceeds a pre-set displacement threshold, dL,
severe end-stop impacts might be prevented.
Figure 6 shows the semi-active control algorithm flow chart for Simulink/Matlab program. This
control flow implements the multi-body dynamic model block (“adams_sub” block) of MSC/ADAMS for
running co-simulation with the control scheme software plug-in. The input to the “adams_sub” block is
damping force, and the three outputs from the block are the seat displacement, x , Floor-pan absolute velocity,
0
x , and the seat absolute velocity, x . Considering the power limitation of Magnetorheological damper for
semi-active skyhook control (Figure 6), the maximum feedback force to the “adams_sub” block was set to
15kN using the “Saturation” block function.
The control scheme can be expressed as:
Lseat
Lseat
ddxxxGG
ddxxxG
Fd
,)21(
,2
0
0
(3)
The control gains, G1 and G2 are functions of passenger weight, and the gains for this study are summarized
in Table 3 for the human body model.
6. Lumped-Parameter Analytical Methodology For Evaluation Of…
60
Figure 6. Simulink control flow diagram for end-stop control
Table 3. Control parameters
Body
model
Small
(5th
%ile)
Female
Medium
(50th
%ile)
Male
Large
(95th
%ile)
Male
Unit
G1 1 2 3 kN/(m/s)
G2 0.01 0.05 0.3 kN/(m/s)
dL 335 335 335 mm
Rotorcraft crash pulse
Based on a study of survivable crash scenarios for U.S. Army helicopters during 1950‟s and 1960‟s,
design guidelines and detailed requirements were developed for military crew seats as defined in MIL-S-
85510(AS) (Military Specification – MIL-S-85510(AS), 1981) and for civil rotorcraft seats in SAE, AS8049
(Aerospace Standard – SAE AS8049A, 1997). Recently Full Spectrum Crashworthiness Criteria for rotorcraft
have been published by U.S. Army RDECOM (Army Aviation Applied Technology Directorate (AATD)) (US
Army RDECOM report RDECOM TR-12-D-12, 2011). Based on these published guidelines, crash pulse for
vertical impacts of military helicopters with a Vz = 42ft/sec (Desjardins et al., 1989; US Army REDCOM
report RDECOM TR-12-D-12, 2011) was used for this research. A typical rotorcraft vertical impact crash pulse
profile as shown schematically in Figure 7 was utilized with seat-occupant model for the analytical evaluation
of passive EA and semi-active MREA. The maximum deceleration and the deceleration-time history
relationship (pulse) developed for the design of a crashworthy seat system for a military helicopter is given
below in Figure 7. In Figure 7, Gm refers to maximum deceleration; tm is the time to reach maximum
deceleration Gm; and GL is the limit-load deceleration. The deceleration of the occupant must be limited to a
level, GL such that the applied loads are of a humanly tolerable time-magnitude relationship. Once the seat-
occupant system reaches this limit load deceleration (GL), the seat strokes at constant load factor keeping the
occupant‟s lumbar load within tolerable limits. After extensive analysis of crash injury data, it was determined
that the limit-load deceleration level should be 14.5g (Military Specification – MIL-S-85510(AS), 1981). So,
the crash energy absorbing systems (EAs) for military helicopter seats should be sized for a limit load that is
14.5 times the effective weight of the seat-occupant system including restraints and other body-worn items.
This limit load factor was later verified by cadaveric testing and analysis as well (Aerospace Standard – SAE
AS8049A, 1997). The limit load, L
L varies with the occupant-seat (O-S) system effective weight and it can be
calculated as follows:
)(5.14 )(
lbWgL effSOL
(4)
Where )()(
lbW effSO
is the effective occupant-seat system weight. For varying occupant sizes (5th
%ile through
95th
%ile occupants), this varying limit load can be calculated, and EA systems can be designed and controlled
to the required stroking load keeping the stroke within allowable design limits.
7. Lumped-Parameter Analytical Methodology For Evaluation Of…
61
Gm = 48g
2tm = 54msec
Vz = 42ft/sec
GL = 14.5g
Figure 7. Typical rotorcraft pulse profile and deceleration limit for the seated occupant (Hiemenz, 2007)
The complete model set-up for simulations are conceptually shown in Figure 8 for the passive EA
(Baseline - no control) and semi-active EA, MREA (with control). The control algorithm was implemented
using co-simulation with seat-occupant dynamic model.
(a) Passive EA (Baseline) (b) Semi-active EA (MREA with Control
Figure 8. Schematic sketch of simulations for Passive EA and MREA (Hiemenz, 2007)
Injury assessment criteria
The key injury assessment parameter such as the lumbar loads would be the primary focus in
comparing the performance benefits of passive EA and MREA. The lumbar load injury assessment reference
values (IARVs) as stipulated in the Full Spectrum Crashworthiness Criteria published by the U.S. Army
Aviation Applied Technology Directorate (AATD) (U.S. Army RDEOM report RDECOM TR-12-D-12, 2011)
were used as reference (Table 4) for evaluation of MREA through analysis. The IARVs for lumbar load injury
criteria for tolerable limits were used for comparison of performance between the passive EA (Baseline) and
MREA with Control cases.
Table 4. Injury Assessment Criteria
Injury Assessment Parameter IARV
Lumbar load < 933 lb for 5th
%ile
< 1395 lb for 50th
%ile
< 1757 lb for 95th
%ile
(per Full Spectrum
Crashworthiness Criteria
guidelines (US Army
RDECOM report RDECOM
TR-12-D-12, 2011))
8. Lumped-Parameter Analytical Methodology For Evaluation Of…
62
Simulation results and discussion
The biodynamic model, shown in Figure 2 and rotorcraft floor model, shown in Figure 3 were
combined and implemented in MSC/ADAMS as shown in Figure 9. An active control element was
implemented and designed to generate force in between floor-pan and seat. The non-linear human biodynamic
model was co-simulated with Simulink control scheme plug-in, as shown in Figure 6. “Co-Simulation” (co-
operative simulation) is a simulation methodology that allows individual components to be simulated using
different simulation tools running simultaneously and exchanging information in a collaborative manner. The
nonlinear human body model in MSC/ADAMS was generated in Simulink accessible code (.m-file and .mdl-
file, “adams_sub” block in Figure 6) through ADAMS/Control module.
Figure 9. A lumped-parameter seat-occupant model
The figures 10 through 12 show the simulation results for three cases, namely, 5th
%ile, 50th
%ile, and 95th
%ile
occupant models. Figure 10 show the reduction of lumbar load for 5th
%ile analysis case between the baseline (passive EA
with no control) and MREA with control. In Figure 10, the peak lumbar load for the Baseline case is 1477 lbf (exceeds
IARV limit), whereas the peak load for MREA with Control analysis case is 926 lbf (< 933 lbf (IARV)). Thus, it has been
shown through analysis that by choosing an adaptive MREA with right type of control algorithm, it is possible to mitigate
thoracic spinal injury (lumbar load is a measure of this injury) to a seated occupant in a rotorcraft vertical crash event. In
Figure 11 for the 50th
%ile analysis case, the peak lumbar load is reduced from 2248 lbf (Baseline) to 1388 lbf (MREA
with Control) keeping the lumbar load well within the IARV limit for this severe crash scenario. Also, in Figure 12 for the
95th
%ile occupant analysis case, it has been shown that the peak lumbar load can be reduced from 2342 lbf to 1748 lbf,
which is well within the IARV limit. These analysis cases show that it is possible to optimize the adaptive MREA device
with a proper control algorithm for the crash scenarios that are of interest to improve the safety and survivability in
rotorcraft crashes.
Figure 10. Baseline vs. MREA with control – for 5th
%ile occupant
Peak Lumbar Load (Baseline) = 1477 lb
Peak Lumbar Load (MREA w/Control) = 926 lb
Lumbar Load - IARV Limit for 5th
%ile = 933lb
9. Lumped-Parameter Analytical Methodology For Evaluation Of…
63
Figure 11. Baseline vs. MREA with control – for 50th
%ile occupant
Figure 12. Baseline vs. MREA with control – for 95th
%ile occupant
Peak Lumbar Load (Baseline) = 2248 lb
Peak Lumbar Load (MREA w/Control) = 1388 lb
Lumbar Load - IARV Limit for 50th
%ile = 1395 lb)
Peak Lumbar Load (Baseline) = 2342 lb
Peak Lumbar Load (MREA w/Control) = 1748 lb
Lumbar Load - IARV Limit for 95th
%ile = 1757 lb)
10. Lumped-Parameter Analytical Methodology For Evaluation Of…
64
Summary and conclusions
This analytical research study proposes a lumped-parameter human body model including lower leg in
seated posture for rotorcraft crashworthiness simulation and crash safety seat development with an adaptive
semi-active seat energy absorber. The multi-body, lumped parameters were developed to represent a seated
occupant in a rotorcraft interior environment. The upper extremity was neglected in the analysis model, since it
is assumed that it has negligible effects on the overall bio-dynamics of the human body during a crash event.
The developed models are applicable for an “average” human subject (close to a 50th
percentile male), a small
female 5th
%ile human subject, and a large male 95th
%ile human subject. The developed rotorcraft vehicle
occupant model, with the chosen parameters, provides a reasonable estimate of the seat-to-head transmissibility
(TR), and driving-point impedance (IM) characteristics defined as applicable to target experimental values for
ensuring bio-fidelity of the model. A generic rotorcraft vertical crash pulse as stipulated in military design
standards was used to evaluate the performance of MREA seat energy absorber with a suitable control
algorithm. The goal of this research was to establish a high fidelity lumped parameter seat-occupant model and
a simulation methodology with a suitable control algorithm that can be used to evaluate and design adaptive
magnetorheological energy absorbers for rotorcraft crashworthy safety seat application. The established model
will also be helpful in the evaluation different types of control schemes for the efficient use of the adaptive
MREAs to meet crew safety requirements with varying occupant sizes and vertical impact sink rates. An
analysis methodology to co-simulate control algorithms together with lumped-parameter, multi-body seat-
occupant system model with adaptive MREA device was demonstrated as well. It has been shown through this
study that lumbar load reduction and consequent spinal injury mitigation can be achieved for all sizes of adults
in a rotorcraft vertical crash event by using an adaptive semi-active seat energy absorber, such as a
magnetorheological energy absorber with a suitable control algorithm to control the energy absorber actuation
during the crash event. A seat-occupant system level test set-up with an “iron-bird” seat (structurally
strengthened seat structure for repeated sled tests) is being built for energy absorber technology demonstration
as part of this research project. Dynamic sled testing with full scale crash loads will be conducted for
demonstration and verification of different types of seat damper technologies in future.
Acknowledgment
The authors would like to acknowledge the research funding awarded by the Joint Aircraft
Survivability Program Office, USA for this research work.
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