This document discusses the optimization of hydro-mechanical power split transmissions. It begins by providing background on continuously variable transmissions and why hydro-mechanical power split transmissions are promising. It then describes the optimization problem as designing the transmission to maximize average efficiency by selecting displacements of the hydraulic machines and gear ratios. An optimization algorithm using particle swarm methods is used to solve this problem. Finally, the optimization method will be applied to study transmissions for a compact loader and agricultural tractor.
Heuristic remedial actions in the reliability assessment of high voltage dire...IJECEIAES
Planning of high voltage direct current (HVDC) grids requires inclusion of reliability assessment of alternatives under study. This paper proposes a methodology to evaluate the adequacy of voltage source converter/VSCHVDC networks. The methodology analyses the performance of the system using N-1 and N-2 contingencies in order to detect weaknesses in the DC network and evaluates two types of remedial actions to keep the entire system under the acceptable operating limits . The remedial actions are applied when a violation of these limits on the DC system occurs; those include topology changes in the network and adjustments of power settings of VSC converter stations. The CIGRE B4 DC grid test system is used for evaluating the reliability/adequacy performance by means of the proposed methodology in this paper. The proposed remedial actions are effective for all contingencies; then, numerical results are as expected. This work is useful for planning and operation of grids based on VSC-HVDC technology.
A novel method for determining fixed running time in operating electric train...IJECEIAES
Tracking the optimal speed profile in electric train operation has been proposed as a potential solution for reducing energy consumption in electric train operation, at no cost to improve infrastructure of existing Metro lines as well. However, the optimal speed profile needs to meet fixed running time. Therefore, this paper focuses on a new method for determining the fixed running time complied with the scheduled timetable when trains track the optimal speed profile. The novel method to ensure the fixed running time is the numerical-analytical one. Calculating accelerating time ta, coasting time tc, braking time tb via values of holding speed vh, braking speed vb of optimal speed profile with the constraint condition: the running time equal to the demand time. The other hands, vh and vb are determined by solving nonlinear equations with constraint conditions. Additionally, changing running time suit for each operation stage of metro lines or lines starting to conduct schedules by the numerical-analytical method is quite easy. Simulation results obtained for two scenarios with data collected from electrified trains of Cat Linh-Ha Dong metro line, Vietnam show that running time complied with scheduled timetables, energy saving by tracking optimal speed profile for the entire route is up to 8.7%, if the running time is one second longer than original time, energy saving is about 11.96%.
Coordinated planning in improving power quality considering the use of nonlin...IJECEIAES
Power quality has an important role in the distribution of electrical energy. The use of non-linear load can generate harmonic spread which can reduce the power quality in the radial distribution system. This research is in form of coordinated planning by combining distributed generation placement, capacitor placement and network reconfiguration to simultaneously minimize active power losses, total harmonic distortion (THD), and voltage deviation as an objective function using the particle swarm optimization method. This optimization technique will be tested on two types of networks in the form 33-bus and 69-bus IEEE Standard Test System to show effectiveness of the proposed method. The use of MATLAB programming shows the result of simulation of increasing power quality achieved for all scenario of proposed method.
Power losses reduction of power transmission network using optimal location o...IJECEIAES
Due to the growth of demand for electric power, electric power loss reduction takes great attention for the power utility. In this paper, a low-level generation or distributed generation (DG) has been used for transmission power losses reduction. Karbala city transmission network (which is the case study) has been represented by using MATLAB m-file to study the load flow and the power loss for it. The paper proposed the particle swarm optimization (PSO) technique in order to find the optimal number and allocation of DG with the objective to decrease power losses as possible. The results show the effect of the optimal allocation of DG on power loss reduction.
Soft Computing Technique Based Enhancement of Transmission System Lodability ...IJERA Editor
Due to the growth of electricity demands and transactions in power markets, existing power networks need to be enhanced in order to increase their loadability. The problem of determining the best locations for network reinforcement can be formulated as a mixed discrete-continuous nonlinear optimization problem (MDCP). The complexity of the problem makes extensive simulations necessary and the computational requirement is high. This paper compares the effectiveness of Evolutionary Programming (EP) and an ordinal optimization (OO) technique is proposed in this paper to solve the MDCP involving two types of flexible ac transmission systems (FACTS) devices, namely static var compensator (SVC) and thyristor controlled series compensator (TCSC), for system loadability enhancement. In this approach, crude models are proposed to cope with the complexity of the problem and speed up the simulations with high alignment confidence. The test and Validation of the proposed algorithm are conducted on IEEE 14–bus system and 22-bus Indian system.Simulation results shows that the proposed models permit the use of OO-based approach for finding good enough solutions with less computational efforts.
Heuristic remedial actions in the reliability assessment of high voltage dire...IJECEIAES
Planning of high voltage direct current (HVDC) grids requires inclusion of reliability assessment of alternatives under study. This paper proposes a methodology to evaluate the adequacy of voltage source converter/VSCHVDC networks. The methodology analyses the performance of the system using N-1 and N-2 contingencies in order to detect weaknesses in the DC network and evaluates two types of remedial actions to keep the entire system under the acceptable operating limits . The remedial actions are applied when a violation of these limits on the DC system occurs; those include topology changes in the network and adjustments of power settings of VSC converter stations. The CIGRE B4 DC grid test system is used for evaluating the reliability/adequacy performance by means of the proposed methodology in this paper. The proposed remedial actions are effective for all contingencies; then, numerical results are as expected. This work is useful for planning and operation of grids based on VSC-HVDC technology.
A novel method for determining fixed running time in operating electric train...IJECEIAES
Tracking the optimal speed profile in electric train operation has been proposed as a potential solution for reducing energy consumption in electric train operation, at no cost to improve infrastructure of existing Metro lines as well. However, the optimal speed profile needs to meet fixed running time. Therefore, this paper focuses on a new method for determining the fixed running time complied with the scheduled timetable when trains track the optimal speed profile. The novel method to ensure the fixed running time is the numerical-analytical one. Calculating accelerating time ta, coasting time tc, braking time tb via values of holding speed vh, braking speed vb of optimal speed profile with the constraint condition: the running time equal to the demand time. The other hands, vh and vb are determined by solving nonlinear equations with constraint conditions. Additionally, changing running time suit for each operation stage of metro lines or lines starting to conduct schedules by the numerical-analytical method is quite easy. Simulation results obtained for two scenarios with data collected from electrified trains of Cat Linh-Ha Dong metro line, Vietnam show that running time complied with scheduled timetables, energy saving by tracking optimal speed profile for the entire route is up to 8.7%, if the running time is one second longer than original time, energy saving is about 11.96%.
Coordinated planning in improving power quality considering the use of nonlin...IJECEIAES
Power quality has an important role in the distribution of electrical energy. The use of non-linear load can generate harmonic spread which can reduce the power quality in the radial distribution system. This research is in form of coordinated planning by combining distributed generation placement, capacitor placement and network reconfiguration to simultaneously minimize active power losses, total harmonic distortion (THD), and voltage deviation as an objective function using the particle swarm optimization method. This optimization technique will be tested on two types of networks in the form 33-bus and 69-bus IEEE Standard Test System to show effectiveness of the proposed method. The use of MATLAB programming shows the result of simulation of increasing power quality achieved for all scenario of proposed method.
Power losses reduction of power transmission network using optimal location o...IJECEIAES
Due to the growth of demand for electric power, electric power loss reduction takes great attention for the power utility. In this paper, a low-level generation or distributed generation (DG) has been used for transmission power losses reduction. Karbala city transmission network (which is the case study) has been represented by using MATLAB m-file to study the load flow and the power loss for it. The paper proposed the particle swarm optimization (PSO) technique in order to find the optimal number and allocation of DG with the objective to decrease power losses as possible. The results show the effect of the optimal allocation of DG on power loss reduction.
Soft Computing Technique Based Enhancement of Transmission System Lodability ...IJERA Editor
Due to the growth of electricity demands and transactions in power markets, existing power networks need to be enhanced in order to increase their loadability. The problem of determining the best locations for network reinforcement can be formulated as a mixed discrete-continuous nonlinear optimization problem (MDCP). The complexity of the problem makes extensive simulations necessary and the computational requirement is high. This paper compares the effectiveness of Evolutionary Programming (EP) and an ordinal optimization (OO) technique is proposed in this paper to solve the MDCP involving two types of flexible ac transmission systems (FACTS) devices, namely static var compensator (SVC) and thyristor controlled series compensator (TCSC), for system loadability enhancement. In this approach, crude models are proposed to cope with the complexity of the problem and speed up the simulations with high alignment confidence. The test and Validation of the proposed algorithm are conducted on IEEE 14–bus system and 22-bus Indian system.Simulation results shows that the proposed models permit the use of OO-based approach for finding good enough solutions with less computational efforts.
Small Signal Stability Improvement and Congestion Management Using PSO Based ...IDES Editor
In this paper an attempt has been made to study the
application of Thyristor Controlled Series Capacitor (TCSC)
to mitigate small signal stability problem in addition to
congestion management of a heavily loaded line in a
multimachine power system. The Flexible AC Transmission
System (FACTS) devices such as TCSC can be used to control
the power flows in the network and can help in improvement
of small signal stability aspect. It can also provide relief to
congestion in the heavily loaded line. However, the
performance of any FACTS device highly depends upon its
parameters and placement at suitable locations in the power
network. In this paper, Particle Swarm Optimization (PSO)
method has been used for determining the optimal locations
and parameters of the TCSC controller in order to damp small
signal oscillations. Transmission Line Flow (TLF) Sensitivity
method has been used for curtailment of non-firm load to
limit power flow congestion. The results of simulation reveals
that TCSC controllers, placed optimally, not only mitigate
small signal oscillations but they can also alleviate line flow
congestion effectively.
Bulk power system availability assessment with multiple wind power plants IJECEIAES
The use of renewable non-conventional energy sources, as wind electric power energy and photovoltaic solar energy, has introduced uncertainties in the performance of bulk power systems. The power system availability has been employed as a useful tool for planning power systems; however, traditional methodologies model generation units as a component with two states: in service or out of service. Nevertheless, this model is not useful to model wind power plants for availability assessment of the power system. This paper used a statistical representation to model the uncertainty of power injection of wind power plants based on the central moments: mean value, variance, skewness and kurtosis. In addition, this paper proposed an availability assessment methodology based on application of this statistical model, and based on the 2m+1 point estimate method the availability assessment is performed. The methodology was tested on the IEEE-RTS assuming the connection of two wind power plants and different correlation among the behavior of these plants.
A probabilistic multi-objective approach for FACTS devices allocation with di...IJECEIAES
This study presents a probabilistic multi-objective optimization approach to obtain the optimal locations and sizes of static var compensator (SVC) and thyristor-controlled series capacitor (TCSC) in a power transmission network with large level of wind generation. In this study, the uncertainties of the wind power generation and correlated load demand are considered. The uncertainties are modeled in this work using the points estimation method (PEM). The optimization problem is solved using the multi-objective particle swarm optimization (MOPSO) algorithm to find the best position and rating of the flexible AC transmission system (FACTS) devices. The objective of the problem is to maximize the system loadability while minimizing the power losses and FACTS devices installation cost. Additionally, a technique based on fuzzy decision-making approach is employed to extract one of the Pareto optimal solutions as the best compromise one. The proposed approach is applied on the modified IEEE 30bus system. The numerical results evince the effectiveness of the proposed approach and shows the economic benefits that can be achieved when considering the FACTS controller.
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.
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.
Investigation on Chassis Dynamometer with Capability to Test Regenerative Bra...IJPEDS-IAES
An investigation-based approach to a bidirectional power flow method for
testing regenerative braking function on a chassis dynamometer is presented.
The requirements and specifications for capability to test regenerative
braking function of Electric Vehicle (EV) emulated by using a bidirectional
chassis dynamometer are discussed. The dynamometer emulates road load
conditions during testing, and regenerative braking is able to test their
function while the vehicle is in deceleration condition. Performances of
power requirement are illustrated and translated into sequence diagram. It is
shown that the proposed topology is particularly advantageous in generating
and regenerating power for energy consumption. The overview of
conventional chassis dynamometer and the proposed chassis dynamometer is
compared to investigate the parameter in the development of regenerative
braking test.
Power Flow Analysis for Four Buses System by NR Methodijtsrd
Power flow studies provide a systematic mathematical approach for determination of various bus voltages, there phase angle, active and reactive power flows through different branches, generators and loads under steady state condition. In this paper, the purpose of power flow analysis is to determine four bus system power flows. Case studies have been performed on Lawpita Taungoo Kamarnat Hlawga 230kV Line Myanmar . This paper presents a reliable method to meet the requirements by developing a Newton Raphson based load flow calculation program through which control setting of Shunt Compensator can be determined directly. This program computes the voltage magnitude and angle at each bus in a power system under balanced steady state conditions. Real and reactive power flows for all buses, as well as line flow and line losses, are also computed. And then the compensation of shunt capacitor is proposed for load flow analysis and also for overall loss minimization and improvement in system voltage profile. Wint Yu Yu Zaw ""Power Flow Analysis for Four Buses System by NR Method"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23472.pdf
Paper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/23472/power-flow-analysis-for-four-buses-system-by-nr-method/wint-yu-yu-zaw
Comparison of Differential Evolution and Particle Swarm Optimization for Opti...IOSRJEEE
This paper proposes an optimization model for the selection of turbines in order to improve the power generation potential in a Hydro Power Plant. The thermal, electrical and mechanical stresses that occur over time on the turbine affect the efficiency of the generating unit. The mathematical formulation for this problem emanates a non-linear programming problem which is therefore solved using Particle Swarm Optimization and Differential Evolution optimizing techniques. These two algorithms are then compared and the results are validated in Dot Net. The Dot Net framework is used due to its extensive security, enhanced usability and flexibility. These optimization techniques are implemented in a case study which is carried out in Murudeshwar Small Hydro Power Plant located in Narayanpur, Bijapur District, India.
Energy-Efficient Driving in the Portuguese Rail Operation (MSc. Dissertation ...João Vieira
The main share of energy consumption in railways consists of traction energy, i.e., energy required to move the trains. The amount of energy consumed is much influenced by the way the train is driven within schedule. As each driver has its own driving style and since the deduction of the energy-efficient driving strategy is not trivial, there are now available Driving Advice Systems to assist drivers in choosing the most energy-efficient actions.
The aim of this study was to develop an energy-efficient driving model in order to derive, for a given route and running time, an energy-efficient speed profile. The driving model was used to build efficient driving strategies for regional and inter-regional rail services in the Douro line. The model’s energy saving potential evaluation was done by using a train-running simulator in order to compare the driver’s actions and speed profiles of real cases with the most efficient driving strategies for the same situations. The simulation results point to an energy saving potential between 11 and 15%, just by changing the driving style.
Finally, a Driver Advice System prototype was developed, in order to assist the driver in adopting an efficient driving strategy. The prototype has been developed for the Android platform, to be implemented in a low-cost equipment, such as a tablet, equipped with GPS receiver.
MODELLING, ANALYSIS AND SIMULATION OF THE PIEZOELECTRIC MICRO PUMPadeij1
The piezoelectricity is a reversible phenomenon, which corresponds to the direct piezoelectric effect. So that, the battery loads arrive at the pump, an electronic module must be established in the circuit. A flow pump must be used and its effectiveness must be evaluated according to the desired need. The system is conceived around 24 hour old clock which can be programmed to provide fluid in variable quantity on a regular basis. The piezo-hydraulic pump presented in this work is composed mainly of shareholder piezoelectric with two valves and a diaphragm of the room reinforced by a hard disk. This one is used to improve the performance of the micro-pump in forecast of pump realization. Modeling, analysis and simulation are carried out under SYMBOLS software.
Speed profile optimization of an electrified train in cat linh-ha dong metro ...IJECEIAES
An urban railway is a complex technical system that consumes large amounts of energy, but this means of transportation still has been obtained more and more popularity in densely populated cities because of its features of highcapacity transportation capability, high speed, security, punctuality, lower emission, reduction of traffic congestion. The improved energy consumption and environment are two of the main objectives for future transportation. Electrified trains can meet these objectives by the recuperation and reuse of regenerative braking energy and by the energy - efficient operation. Two methods are to enhance energy efficiency: one is to improve technology (e.g., using energy storage system, reversible or active substations to recuperate regenerative braking energy, replacing traction electric motors by energy-efficient traction system as permanent magnet electrical motors; train's mass reduction by lightweight material mass...); the other is to improve operational procedures (e.g. energy efficient driving including: ecodriving; speed profile optimization; Driving Advice System (DAS); Automatic Train Operation (ATO); traffic management optimization...). Among a lot of above solutions for saving energy, which one is suitable for current conditions of metro lines in Vietnam. The paper proposes the optimization method based on Pontryagin's Maximum Principle (PMP) to find the optimal speed profile for electrified train of Cat Linh-Ha Dong metro line, Vietnam in an effort to minimize the train operation energy consumption.
MODELING AND OPTIMIZATION OF PIEZOELECTRIC ENERGY HARVESTING adeij1
In this paper, the modeling, optimization and simulation results of the piezoelectric energy harvesting using bond graph approach are presented. Firstly, a lightweight equivalent model derived from the bond graph is proposed. It’s a comprehensive model, which is suitable for piezoelectric seismic energy harvester investigation and power optimization. The optimal charge impedance for both the resistive load and complex load are given and analysed. Finally a bond graph approach is proposed to allow optimization of the extracted energy while keeping simplicity and standalone capability. The proposed model does not rely on any inductor and is constructed with a simple switch. The power harvested is more than twice the conventional technique one on a wide band of resistive load. The bond graph model is valid close to the analysed mode centre frequency and delivers results compared to experimental and analytical data. Furthermore, we also show that the harvester can be electrically tuned to match the excitation frequency. This makes it possible to maximize the power output for both linear and non-linear loads.
Design and Experimental Results of Universal Electric Vehicle Charger Using DSPTELKOMNIKA JOURNAL
Owing to the growing concerns over energy depletion and environmental issues around the
world, more and more attention is given on replacing the fuel -based automobiles with electric vehicles
(EVs) which have the characteristics of zero-emission and low noise. As a result, various countries have
taken specific initiatives to de-carbonize their transport sectors by developing their own EV industry.
Regardless of the environmental and economic benefits, substantial scales of grid-connected EVs impose
incredible difficulties to the power grid. The main issues caused by EV charging to the power grid include
harmonics, voltage drop, system instability, system losses and grid overloading. Therefore, this paper
presents design and development of a novel method, which is by applying voltage-oriented control (VOC)
algorithm in battery charging of electric bus.The power system of this work consists of three-phase PWM
rectifier. The proposed method is based on mathematical analysis. Simulation and experimental works are
performed to investigate behavior and performance of the proposed algorithm. This paperclearly described
implementation of low and medium power laboratory prototype and operation of digital signal processor
(DSP) via MATLAB / Simulink for the proposed method.
A Study on PHERB Powertrain Modeling and AnalysisIJECEIAES
A study on plug-in hybrid electric recreational boat (PHERB) powertrain with a special energy management strategy modeling and analysis was presented in this paper. Firstly, the boat components are sized to meet the expected power and energy requirements through a power flow analysis. Then, the model is tested numerically in the MATLAB/SIMULINK environment using the existing driving cycle. The accuracy of the model is verified by a comparison of the component between the simulation results from PHERB and advanced vehicle simulator (ADVISOR) software. The simulation results of component, fuel economy and emission of PHERB and hybrid electric vehicle models in ADVISOR are compared.
Small Signal Stability Improvement and Congestion Management Using PSO Based ...IDES Editor
In this paper an attempt has been made to study the
application of Thyristor Controlled Series Capacitor (TCSC)
to mitigate small signal stability problem in addition to
congestion management of a heavily loaded line in a
multimachine power system. The Flexible AC Transmission
System (FACTS) devices such as TCSC can be used to control
the power flows in the network and can help in improvement
of small signal stability aspect. It can also provide relief to
congestion in the heavily loaded line. However, the
performance of any FACTS device highly depends upon its
parameters and placement at suitable locations in the power
network. In this paper, Particle Swarm Optimization (PSO)
method has been used for determining the optimal locations
and parameters of the TCSC controller in order to damp small
signal oscillations. Transmission Line Flow (TLF) Sensitivity
method has been used for curtailment of non-firm load to
limit power flow congestion. The results of simulation reveals
that TCSC controllers, placed optimally, not only mitigate
small signal oscillations but they can also alleviate line flow
congestion effectively.
Bulk power system availability assessment with multiple wind power plants IJECEIAES
The use of renewable non-conventional energy sources, as wind electric power energy and photovoltaic solar energy, has introduced uncertainties in the performance of bulk power systems. The power system availability has been employed as a useful tool for planning power systems; however, traditional methodologies model generation units as a component with two states: in service or out of service. Nevertheless, this model is not useful to model wind power plants for availability assessment of the power system. This paper used a statistical representation to model the uncertainty of power injection of wind power plants based on the central moments: mean value, variance, skewness and kurtosis. In addition, this paper proposed an availability assessment methodology based on application of this statistical model, and based on the 2m+1 point estimate method the availability assessment is performed. The methodology was tested on the IEEE-RTS assuming the connection of two wind power plants and different correlation among the behavior of these plants.
A probabilistic multi-objective approach for FACTS devices allocation with di...IJECEIAES
This study presents a probabilistic multi-objective optimization approach to obtain the optimal locations and sizes of static var compensator (SVC) and thyristor-controlled series capacitor (TCSC) in a power transmission network with large level of wind generation. In this study, the uncertainties of the wind power generation and correlated load demand are considered. The uncertainties are modeled in this work using the points estimation method (PEM). The optimization problem is solved using the multi-objective particle swarm optimization (MOPSO) algorithm to find the best position and rating of the flexible AC transmission system (FACTS) devices. The objective of the problem is to maximize the system loadability while minimizing the power losses and FACTS devices installation cost. Additionally, a technique based on fuzzy decision-making approach is employed to extract one of the Pareto optimal solutions as the best compromise one. The proposed approach is applied on the modified IEEE 30bus system. The numerical results evince the effectiveness of the proposed approach and shows the economic benefits that can be achieved when considering the FACTS controller.
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.
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.
Investigation on Chassis Dynamometer with Capability to Test Regenerative Bra...IJPEDS-IAES
An investigation-based approach to a bidirectional power flow method for
testing regenerative braking function on a chassis dynamometer is presented.
The requirements and specifications for capability to test regenerative
braking function of Electric Vehicle (EV) emulated by using a bidirectional
chassis dynamometer are discussed. The dynamometer emulates road load
conditions during testing, and regenerative braking is able to test their
function while the vehicle is in deceleration condition. Performances of
power requirement are illustrated and translated into sequence diagram. It is
shown that the proposed topology is particularly advantageous in generating
and regenerating power for energy consumption. The overview of
conventional chassis dynamometer and the proposed chassis dynamometer is
compared to investigate the parameter in the development of regenerative
braking test.
Power Flow Analysis for Four Buses System by NR Methodijtsrd
Power flow studies provide a systematic mathematical approach for determination of various bus voltages, there phase angle, active and reactive power flows through different branches, generators and loads under steady state condition. In this paper, the purpose of power flow analysis is to determine four bus system power flows. Case studies have been performed on Lawpita Taungoo Kamarnat Hlawga 230kV Line Myanmar . This paper presents a reliable method to meet the requirements by developing a Newton Raphson based load flow calculation program through which control setting of Shunt Compensator can be determined directly. This program computes the voltage magnitude and angle at each bus in a power system under balanced steady state conditions. Real and reactive power flows for all buses, as well as line flow and line losses, are also computed. And then the compensation of shunt capacitor is proposed for load flow analysis and also for overall loss minimization and improvement in system voltage profile. Wint Yu Yu Zaw ""Power Flow Analysis for Four Buses System by NR Method"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-3 , April 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23472.pdf
Paper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/23472/power-flow-analysis-for-four-buses-system-by-nr-method/wint-yu-yu-zaw
Comparison of Differential Evolution and Particle Swarm Optimization for Opti...IOSRJEEE
This paper proposes an optimization model for the selection of turbines in order to improve the power generation potential in a Hydro Power Plant. The thermal, electrical and mechanical stresses that occur over time on the turbine affect the efficiency of the generating unit. The mathematical formulation for this problem emanates a non-linear programming problem which is therefore solved using Particle Swarm Optimization and Differential Evolution optimizing techniques. These two algorithms are then compared and the results are validated in Dot Net. The Dot Net framework is used due to its extensive security, enhanced usability and flexibility. These optimization techniques are implemented in a case study which is carried out in Murudeshwar Small Hydro Power Plant located in Narayanpur, Bijapur District, India.
Energy-Efficient Driving in the Portuguese Rail Operation (MSc. Dissertation ...João Vieira
The main share of energy consumption in railways consists of traction energy, i.e., energy required to move the trains. The amount of energy consumed is much influenced by the way the train is driven within schedule. As each driver has its own driving style and since the deduction of the energy-efficient driving strategy is not trivial, there are now available Driving Advice Systems to assist drivers in choosing the most energy-efficient actions.
The aim of this study was to develop an energy-efficient driving model in order to derive, for a given route and running time, an energy-efficient speed profile. The driving model was used to build efficient driving strategies for regional and inter-regional rail services in the Douro line. The model’s energy saving potential evaluation was done by using a train-running simulator in order to compare the driver’s actions and speed profiles of real cases with the most efficient driving strategies for the same situations. The simulation results point to an energy saving potential between 11 and 15%, just by changing the driving style.
Finally, a Driver Advice System prototype was developed, in order to assist the driver in adopting an efficient driving strategy. The prototype has been developed for the Android platform, to be implemented in a low-cost equipment, such as a tablet, equipped with GPS receiver.
MODELLING, ANALYSIS AND SIMULATION OF THE PIEZOELECTRIC MICRO PUMPadeij1
The piezoelectricity is a reversible phenomenon, which corresponds to the direct piezoelectric effect. So that, the battery loads arrive at the pump, an electronic module must be established in the circuit. A flow pump must be used and its effectiveness must be evaluated according to the desired need. The system is conceived around 24 hour old clock which can be programmed to provide fluid in variable quantity on a regular basis. The piezo-hydraulic pump presented in this work is composed mainly of shareholder piezoelectric with two valves and a diaphragm of the room reinforced by a hard disk. This one is used to improve the performance of the micro-pump in forecast of pump realization. Modeling, analysis and simulation are carried out under SYMBOLS software.
Speed profile optimization of an electrified train in cat linh-ha dong metro ...IJECEIAES
An urban railway is a complex technical system that consumes large amounts of energy, but this means of transportation still has been obtained more and more popularity in densely populated cities because of its features of highcapacity transportation capability, high speed, security, punctuality, lower emission, reduction of traffic congestion. The improved energy consumption and environment are two of the main objectives for future transportation. Electrified trains can meet these objectives by the recuperation and reuse of regenerative braking energy and by the energy - efficient operation. Two methods are to enhance energy efficiency: one is to improve technology (e.g., using energy storage system, reversible or active substations to recuperate regenerative braking energy, replacing traction electric motors by energy-efficient traction system as permanent magnet electrical motors; train's mass reduction by lightweight material mass...); the other is to improve operational procedures (e.g. energy efficient driving including: ecodriving; speed profile optimization; Driving Advice System (DAS); Automatic Train Operation (ATO); traffic management optimization...). Among a lot of above solutions for saving energy, which one is suitable for current conditions of metro lines in Vietnam. The paper proposes the optimization method based on Pontryagin's Maximum Principle (PMP) to find the optimal speed profile for electrified train of Cat Linh-Ha Dong metro line, Vietnam in an effort to minimize the train operation energy consumption.
MODELING AND OPTIMIZATION OF PIEZOELECTRIC ENERGY HARVESTING adeij1
In this paper, the modeling, optimization and simulation results of the piezoelectric energy harvesting using bond graph approach are presented. Firstly, a lightweight equivalent model derived from the bond graph is proposed. It’s a comprehensive model, which is suitable for piezoelectric seismic energy harvester investigation and power optimization. The optimal charge impedance for both the resistive load and complex load are given and analysed. Finally a bond graph approach is proposed to allow optimization of the extracted energy while keeping simplicity and standalone capability. The proposed model does not rely on any inductor and is constructed with a simple switch. The power harvested is more than twice the conventional technique one on a wide band of resistive load. The bond graph model is valid close to the analysed mode centre frequency and delivers results compared to experimental and analytical data. Furthermore, we also show that the harvester can be electrically tuned to match the excitation frequency. This makes it possible to maximize the power output for both linear and non-linear loads.
Design and Experimental Results of Universal Electric Vehicle Charger Using DSPTELKOMNIKA JOURNAL
Owing to the growing concerns over energy depletion and environmental issues around the
world, more and more attention is given on replacing the fuel -based automobiles with electric vehicles
(EVs) which have the characteristics of zero-emission and low noise. As a result, various countries have
taken specific initiatives to de-carbonize their transport sectors by developing their own EV industry.
Regardless of the environmental and economic benefits, substantial scales of grid-connected EVs impose
incredible difficulties to the power grid. The main issues caused by EV charging to the power grid include
harmonics, voltage drop, system instability, system losses and grid overloading. Therefore, this paper
presents design and development of a novel method, which is by applying voltage-oriented control (VOC)
algorithm in battery charging of electric bus.The power system of this work consists of three-phase PWM
rectifier. The proposed method is based on mathematical analysis. Simulation and experimental works are
performed to investigate behavior and performance of the proposed algorithm. This paperclearly described
implementation of low and medium power laboratory prototype and operation of digital signal processor
(DSP) via MATLAB / Simulink for the proposed method.
A Study on PHERB Powertrain Modeling and AnalysisIJECEIAES
A study on plug-in hybrid electric recreational boat (PHERB) powertrain with a special energy management strategy modeling and analysis was presented in this paper. Firstly, the boat components are sized to meet the expected power and energy requirements through a power flow analysis. Then, the model is tested numerically in the MATLAB/SIMULINK environment using the existing driving cycle. The accuracy of the model is verified by a comparison of the component between the simulation results from PHERB and advanced vehicle simulator (ADVISOR) software. The simulation results of component, fuel economy and emission of PHERB and hybrid electric vehicle models in ADVISOR are compared.
With the computer revolution digital data has become available. With the Internet and smart connected product, the data is growing exponentially. With all this data, it becomes a platform for something new of its own. In this lecture, we look at what big data is and look at several examples of how to use data.
Neste trabalho os autores apresentarão um ensaio preditivo proposto para monitorar e garantir a extensão de vida útil de rotores Kaplan baseado em análise por elementos finitos, ensaios dinâmicos e no cálculo de estimativa de vida útil remanescente dos componentes internos do rotor Kaplan das unidades geradoras.
This is aimed to explain the isolation of carbohydrates and starch from plant source. To also verify the presence of carbohydrates from the isolation process through several qualitative tests and qualitative tests for monosaccharides, disaccharides and polysaccharides
Our company has earned a reputation for developing innovative products for contemporary dentistry and promoting the benefits of dental research designed to help both dentists and patients worldwide.
This extraordinary commitment is expressed in our corporate motto “Bringing Science to the Art of Dentistry".
Our philosophy is to identify and meet your needs, coach you in the use of our products, and provide additional educational resources so you can provide your patients with the best possible dental care.
CCPB: registro prodotti certificati 2017 febbraioccpbsrl
Il registro dei certificati raccoglie tutte le principali informazioni inerenti le certificazioni emesse da CCPB srl nell’ambito degli schemi di certificazione del sistema di certificazione in ambito volontario
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.t
Hybrid Power Systems for Construction Machinery: Aspects of System Design and...Reno Filla
This paper will examine the wheel loader as a system with two parallel energy conversion systems that show a complex interaction with each other and with the power source. Using a systematic design approach, several principle design solutions for hybridization can be found.
Furthermore, the human operator with his/her control actions needs to be considered as part of the total system. This paper will therefore also connect to results from ongoing and previous research into operator workload and operability.
http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-51999
http://dx.doi.org/10.1115/IMECE2009-10458
Hydrostatic Continuous Variable Power Transmission Drive for Two wheelers usi...ijsrd.com
Power transmission is an extremely important factor for the automotive industry today. In vehicles, the power transmission system is the major source of energy losses. This is an intentionally compact review for a module addressing basic Fluid Mechanics for incompressible fluids within the context of Applied Energy Systems. Rather than attempting to cover Fluid Mechanics in a very broad and general way, two practical areas are selected in the use of fluids, hydrostatic power transmission systems and the flow of fluids through pipes and fittings. Thus readers are prepared for applying the same and similar principles to a much broader range of practical applications in the future. The present review work relates to a rotary pump and motor transmission system, which permits a change in ratio between the speed of the driver and driven shafts from direct drive to neutral position. This transmission, which may be adopted for many uses, such as vehicles and machine tools, is endowed with the utmost ease of operation even under load, is of a simple and rugged construction and offers safety of operation even after an extended use.
Evaluating the efficiency of wheel loader bucket designs and bucket filling s...Reno Filla
In this paper we outline how optimising bucket design and bucket filling is connected to improving the total energy efficiency of a wheel loader. Results from our work with particle simulations are shown and it is discussed that, while ideally such simulations should be coupled to models of the machine, operator and the work environment, it is nonetheless possible to simulate stand-alone and utilise simple performance indicators to compare different bucket designs and different bucket filling strategies in a reasonably fair manner. Suitable and less suitable performance indicators are derived and discussed in detail.
A significant share of energy consumed by rail systems is
used to move the trains [1]. In our opinion, it is necessary to study
carefully the efficiency of freight electric locomotives in different
modes of operation.
Modern freight electric locomotives have a multi-engine
electric traction drive (up to 16 traction motors) with tractive
effort control system on each axle. Therefore, the approach of
the Scalable Power Control Technology [2,3], which regulates the quantity of locomotive traction motors (TM) in traction mode, seems quite reasonable. In our case, if full locomotive tractive
power is not needed within operation, the redundant motors must be automatically switched off [4,5]. But when additional tractive power is required, the locomotive must use sufficient number of motors.
Optimal power flow based congestion management using enhanced genetic algorithmsIJECEIAES
Congestion management (CM) in the deregulated power systems is germane and of central importance to the power industry. In this paper, an optimal power flow (OPF) based CM approach is proposed whose objective is to minimize the absolute MW of rescheduling. The proposed optimization problem is solved with the objectives of total generation cost minimization and the total congestion cost minimization. In the centralized market clearing model, the sellers (i.e., the competitive generators) submit their incremental and decremental bid prices in a real-time balancing market. These can then be incorporated in the OPF problem to yield the incremental/ decremental change in the generator outputs. In the bilateral market model, every transaction contract will include a compensation price that the buyer-seller pair is willing to accept for its transaction to be curtailed. The modeling of bilateral transactions are equivalent to the modifying the power injections at seller and buyer buses. The proposed CM approach is solved by using the evolutionary based Enhanced Genetic Algorithms (EGA). IEEE 30 bus system is considered to show the effectiveness of proposed CM approach.
The gravitational search algorithm for incorporating TCSC devices into the sy...IJECEIAES
This paper proposes a gravitational search algorithm (GSA) to allocate the thyristor-controlled series compensator (TCSC) incorporation with the issue of reactive power management. The aim of using TCSC units in this study is to minimize active and reactive power losses. Reserve beyond the thermal border, enhance the voltage profile and increase transmission-lines flow while continuing the whole generation cost of the system a little increase compared with its single goal base case. The optimal power flow (OPF) described is a consideration for finding the best size and location of the TCSCs devices seeing techno-economic subjects for minimizing fuel cost of generation units and the costs of installing TCSCs devices. The GSA algorithm's high ability in solving the proposed multi-objective problem is tested on two 9 and 30 bus test systems. For each test system, four case studies are considered to represent both normal and emergency operating conditions. The proposed GSA method's simulation results show that GSA offers a practical and robust highquality solution for the problem and improves system performance.
Hybrid fuel cell-supercapacitor system: modeling and energy management using ...IJECEIAES
The increasing adoption of electric vehicles (EVs) presents a promising solution for achieving sustainable transportation and reducing carbon emissions. To keep pace with technological advancements in the vehicular industry, this paper proposes the development of a hybrid energy storage system (HESS) and an energy management strategy (EMS) for EVs, implemented using Proteus Spice Ver 8. The HESS consists of a proton exchange membrane fuel cell (PEMFC) as the primary source and a supercapacitor (SC) as the secondary source. The EMS, integrated into an electronic board based on the STM32, utilizes a low-pass filter algorithm to distribute energy between the sources. The accuracy of the proposed PEMFC and SC models is validated by comparing Proteus simulation results with experimental tests conducted on the Bahia didactic bench and Maxwell SC bench, respectively. To optimize energy efficiency, simulations of the HESS system involve adjusting the hybridization rate through changes in the cutoff frequency. The analysis compares the state-of-charge (SOC) of the SC and the voltage efficiency of the fuel cell (FC), across different frequencies to optimize overall system performance. The results highlight that the chosen strategy satisfies the energy demand while preserving the FC’s dynamic performance and optimizing its utilization to the maximum.
Data Driven Energy Economy Prediction for Electric City Buses Using Machine L...Shakas Technologies
Data Driven Energy Economy Prediction for Electric City Buses Using Machine Learning.
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Controller design for gantry crane system using modified sine cosine optimiza...TELKOMNIKA JOURNAL
The objective of this research paper is to design a control system to optimize the operating works of the gantry crane system. The dynamic model of the gantry crane system is derived in terms of trolley position and payload oscillation, which is highly nonlinear. The crane system should have the capability to transfer the material to destination end with desired speed along with reducing the load oscillation, obtain expected trolley position and preserving the safety. Proposed controlling method is based on the proportional-integral-derivative (PID) controller with a series differential compensator to control the swinging of the payload and the system trolley movement in order to perform the optimum utilization of the gantry crane. Standard sine cosine optimization algorithm is one of the most-recent optimization techniques based on a stochastic algorithm was presented to tune the PID controller with a series differential compensator. Furthermore, the considered optimization algorithm is modified in order to overcome the inherent drawbacks and solve complex benchmark test functions and to find the optimal design's parameters of the proposed controller. The simulation results show that the modified sine cosine optimization algorithm has better global search performance and exhibits good computational robustness based on test functions. Moreover, the results of testing the gantry crane model reveal that the proposed controller with standard and modified algorithms is effective, feasible and robust in achieving the desired requirements.
Model Validation and Control of an In-Wheel DC Motor Prototype for Hybrid El...Scientific Review SR
In this paper, a mathematical model and a controller for a DC motor are developed for the
construction of an in-wheel motor. In-wheel motors can be used in hybrid electric vehicles to provide traction
force of front or rear wheels. The model identification is achieved using a simple and low cost data acquisition
system. An Arduino Uno embedded board system is used to collect data from sensors to a computer and for
control purposes. Data processing is performed using Matlab/Simulink. Validations of the devel oped
mathematical model and controller performance are carried out by comparing simulation and experimental results.
The results obtained show that the mathematical model is accurate enough to assist in speed controller design and
implementation.
Design and Analysis of Mechanism for Dynamic Characterization of Power Transm...iosrjce
Power transmission systems are being widely used for transmission of power between two members.
Once a particular transmission system is realized it needs to be qualified before its course of application. As
part of this intended torque of the transmission systems needs to be measured and tested. Conventional means of
dynamic characterization of power transmission system has got the demerit of energy consumption to a greater
extent. Because of this more effort is to be put in terms of power for the sake of testing the intended system.
Great need exists for a system which consumes less or ideally no energy while performing test. This project
aims at evolution of a novel technique for evaluating the torque transmitting capability of power transmission
systems without consuming more energy. To start with all the subsystems of the proposed design will be
identified and each of them will be designed for getting their dimensions. Then these dimensional models will be
transformed to solid model of the assembled configuration using 3D CAD software. Functional load which will
be experienced by this design will be assessed and structural analysis will be carried out against these loads
using Finite Element Method (FEM) in commercial FEA software i.e. ANSYS
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
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Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
2. From these considerations, it can be inferred that the efficiency requirements cannot be satisfied only by a directly coupled CVT.
For this reason, a novel type of transmission was designed, in which the power is transmitted partly via a mechanical path, i.e. in an
efficient path, and partly through a CVT. The two powers are then summed by means of a planetary gearing. In this way, the
transmission is still a continuously variable transmission but with efficiency higher than that of the CVT taken individually, since
the transmission efficiency can be calculated as the weighted efficiency of the two paths. This type of transmission is called power
split transmission.
The power-split configuration currently producing the best compromise between efficiency and cost seems to be the hydro-
mechanical power split transmission, where the variable element is the hydrostatic transmission. It offers significant growth
potential thanks to its many possible configurations. Kress [1] classifies four configurations: the so-called “input coupled” (Fig. 1),
“output coupled” (Fig. 2), “hydraulic differential” (Fig. 3), and the 4 shafts solution, called “compound” (Fig. 4). Within the first two
configurations there are also other possible variations, as shown by Jarkow [2].
The hydro-mechanical transmission, although known for decades, only recently has found applications in standard machines.
The first was the Fendt Vario in 1996. It is an integrated output coupled by two traditional gears allowing the vehicle to reach
speeds of 50 km/h. In 2000, the Steyr S-Matic was launched, followed by ZF (2001) and John Deere's “Auto Power”; all three have
input coupled compound transmissions with 4 or 5 shafts.
The literature on this subject is abundant, but here only the main work will be summarized. In the above cited work [1], Kress
studies the performance of the four solutions in Figs. 1–4, assuming as constant, for simplicity, the efficiency of the hydrostatic
section. Kress does not suggest a best configuration among those examined, but highlights the potential of the power split solution
for applications in traction. Resch and Renius [3] provide a comprehensive overview of the problem of hydro-mechanical
transmissions. They define the minimum characteristics of a transmission technology for agricultural machines, in terms of speed
and load. Furthermore they analyze the operation and the efficiency of the two classical types: input and output coupled.
Orshansky [4] analyzes the operation of the hydro-mechanical transmission with 3 planetary gearings (multi-range), and
shows the advantages, while Kireijczyk [5] simulates the operation of a transmission of a similar configuration. Ross [6] outlines
the design procedure of the Sundstrand Corporation Responder's transmission, an input coupled for heavy vehicles.
A comparison of different solutions for a heavy vehicle is made by Blake et al. [7]: input coupled and output coupled and their
complex versions (dual stage and compound, respectively); it follows that the complex solutions are suitable for large power and
particularly for agricultural tractors.
Krauss and Ivantysynova [8] observed that the purely hydrostatic solution with twin motors is still interesting for its simple
construction compared with an output coupled solution.
The power-split transmission is suitable also for the hybrid solutions, as suggested by Miller [9] and Kumar et al. [10]: they
propose a dual stage drive with inertial energy storage for commercial vehicles and earth moving; the energy savings are up to
22%.
The design of such a complex system requires the use of specific calculation codes in order to test different preliminary designs
and find the most efficient solution. Two different approaches may be used in order to model the transmission system: the steady
state approach or the time dependent approach. Several commercial general purpose codes [11,12] refer to the latter, while many
academic “ad hoc” codes make use of the former [13,14]. Even though less detailed than dynamic analysis, the steady state analysis
is generally faster and can still supply useful information on the transmission performance, as long as detailed loss functions for
the hydraulic machines models are used, i.e. loss models taking into account the influence of the pressure, speed and displacement
[13]. For example Ivantysynova and Mikeska [13] proposed a modular software that enables the creation of various configurations
and their steady state performance simulation. The accuracy of results is guaranteed by loss models for volumetric machines of the
polynomial type; the models are derived from the measurement of a large number of machines. This same software tool is then
used by the research group in subsequent works [7,8,10]. Even Casoli et al. [14] proposed a procedure for the stationary simulation
of an input coupled transmission of a commercial machine; similar to [13], the efficiencies of hydrostatic machines are polynomial
expressions derived from experimental data.
A tool like the one proposed in [13] is essentially a verification tool, which allows the performance evaluation of a fixed
configuration whose design parameters (the displacement of machinery and gear ratios of the different gearing) have been
Fig. 1. Layout of the input coupled configuration.
1902 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
3. selected in advance by appropriate criteria. An optimization tool, on the contrary, could provide the optimal values of these
parameters allowing good preliminary design choices.
Since the problem is strongly nonlinear, direct search algorithms could be preferred to classical numerical methods, because
they do not require the calculation of the derivatives, but only that of the objective function. In particular, the method of swarms
(Particle Swarm Optimization (PSO)) and its evolutions seems well suited for the present problem, because, in addition to high
speed of convergence, it is able to “escape” the local extrema and to reach the global one [15].
The optimization procedure for power-split transmissions presented here is based on a stationary model, with hydraulic
machine's efficiencies depending on the operating conditions, and a particle swarm method as optimizer; the average efficiency
over the entire vehicle speed range is used as an objective function, since it is related to the actual fuel economy of the vehicle. The
aim of the procedure is the sizing of the hydrostatic machines and the calculation of the transmission ratios of planetary and
ordinary gearings, in order to lead to the maximum transmission efficiency.
The procedure will be applied to the cases of a compact loader and a high power tractor.
2. Power-split model
The instantaneous state of the transmission was described by means of the speed vector →ω and torque vector →m, where the
components of these vectors are the angular velocities and torques of all the transmission shafts. These vectors are related to the
transmission layout, by means of a nonlinear equation system:
Ω →
ω; →
m
À ÁÂ Ã
·→
ω = bω
M →
ω; →
m
À ÁÂ Ã
·→
m = bm: ð1Þ
The matrices Ω and M were obtained from kinematic and dynamic relations imposed by individual components and
connections of the transmission and depend on the transmission state
→
ω; →
m
À Á
when the load effects of efficiency are considered.
The terms bω and bm are the known speeds and torques.
The model will be described in detail in the following sections, along with the optimization technique.
2.1. The hydrostatic variable unit
The key element of the power split drives is the hydrostatic transmission (HST), which is sketched in Fig. 5.
It is made up of two reversible variable displacement machines with maximum displacement equal to VI and VII. By varying the
displacements it is possible to continuously change the speed in the ideal range [+∞,−∞]. Energy losses and structural limitations
Fig. 2. Layout of the output coupled configuration.
Fig. 3. Layout of the hydraulic differential configuration.
1903A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
4. of the machines, however, restrict this range, forcing the introduction of gears τI and τII in order to adjust the speed of each
hydrostatic unit inside an allowable range. The transmission ratios are defined as follows:
ω
0
I = τIωI
ω
0
II = τIIωII:
ð2Þ
The fundamental equations regulating the power transmission through the unit are listed below and are derived in ideal
conditions directly from the law of continuity and from the uniqueness of the pressure drop produced by the two units:
τIαIVI −τIIαIIVII½ Š
ωI
ωII
& '
= 0 ð3Þ
1
τIαIVI
−
1
τIIαIIVII
!
mI
mII
& '
= 0 ð4Þ
where αI and αII are the actual to maximum displacement ratio of the two units.
In actual conditions, Eqs. 3 and 4 are modified as follows:
τIαIVIη
k
v I −τIIαIIVIIη
−k
vII
h i
ωI
ωII
& '
= 0 ð5Þ
ηhymIηnI
gear
k
τIαIVI
−
ηhymIIηnII
gear
−k
τIIαIIVII
2
4
3
5 mI
mII
'
= 0 ð6Þ
where the exponent k is a function of the power flow direction. In particular, k=1 if the power goes from I unit to II unit; k=−1 in
the opposite case; the efficiencies ηv and ηhym are respectively the volumetric and hydro-mechanical efficiency of units I and II,
Fig. 4. Layout of the compound configuration.
Fig. 5. Hydrostatic CVT.
1904 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
5. whereas the ηgear takes into account the mechanical losses in the ordinary gears. The exponents nI and nII represent the number of
gear pairs needed to achieve the gear ratio τI and τII; they are estimated on the basis of τmax, the maximum allowable value for each
gear pairs:
nI = int τI = τmaxð Þ ð7Þ
nII = int τII = τmaxð Þ: ð8Þ
The efficiency of each gear pair ηgear was assumed to be 0.98, while the maximum gear ratio for each pair τmax was assumed
equal to 2.
In order to take into account the influence on operating conditions, i.e. influence of pressure, speed and displacement, the
volumetric and hydro-mechanical efficiencies of the hydraulic machines were expressed by the following relationship:
ηv = ηref ·χ
v
ω
ω
ωmax
·χ
v
α;p α;
Δp
Δpmax
ð9Þ
Fig. 6. Effect of speed on volumetric efficiency.
Fig. 7. Effect of pressure and actual to maximum displacement ratio on volumetric efficiency.
1905A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
6. ηhy = ηref ·χ
hy
ω
ω
ωmax
·χ
hy
α;p α;
Δp
Δpmax
: ð10Þ
ηref is the reference efficiency value, assumed to be 0.96 for both efficiencies, reduced by coefficients χω and χα, p. The former
coefficient depends on the speed, and the latter depends on the pressure and displacement, as shown in Figs. 6–9.
The laws of χω and χα, p were derived from Wilson-type [16] loss models, whose coefficients were calibrated according to a set
of experimental data [17]; the laws are also in agreement with the trends shown by Casoli et al. [14].
2.2. Mechanical elements
The main mechanical elements of the power split transmission, i.e. the planetary gearing and the three shaft ordinary gearing,
are showed in Fig. 10.
Fig. 8. Effect of speed on hydro-mechanical efficiency.
Fig. 9. Effect of pressure and actual to maximum displacement ratio on hydro-mechanical efficiency.
1906 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
7. The kinematic equations used for the three shaft gear are the following:
1 0 −1
1 1 0
! ω1
ω2
ω3
8
:
9
=
;
= 0 ð11Þ
1 −1 1½ Š
m1
m2
m3
8
:
9
=
;
= 0 ð12Þ
in which a unit transmission ratio has been used. Any reduction or multiplication ratios, as well as the gears efficiency, can be
considered incorporated in the gears modeled by τI and τII, as part of the CVT element.
The speed and torque equations of a simple planetary gearing are:
1−Tð Þ −1 + T½ Š
ωc
ωr
ωs
8
:
9
=
;
= 0 ð13Þ
Fig. 10. Scheme of a three shaft ordinary gear (a), and of a simple planetary gear (b).
Fig. 11. Scheme of a possible power split configuration.
1907A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
8. 1 1−Tη−t
0
0
0 Tη−t
0 1
2
4
3
5
mc
mr
ms
8
:
9
=
;
= 0 ð14Þ
where T is the standing transmission ratio and ηo is the efficiency of the planetary gearing, assumed equal to 0.985.
The exponent t depends on the power flow inside the gear: for a three shaft planetary gearing 12 different operating conditions
can be identified [11]. The parameter t can take ±1 values and can be synthetically expressed as a function of the incoming power
from the solar, measured in relative reference to the carrier: t=sign([ms(ωs −ωc)]).
2.3. Definition and resolution of the system
Eqs. 5, 6 and 11–14 allow the definition of a system of four equations and eight unknowns; three more equations that take into
account the links between elements are then added; for the case of Fig. 11 (input coupled) they are:
ω3−ωs = 0
ω2−ωI = 0
ωr−ωII = 0
8
:
ð15Þ
and similarly for the torques:
m3 + ms = 0
m2 + mI = 0
mr + mII = 0
:
8
:
ð16Þ
Fig. 12. Flow chart of the iterative solution of the system.
1908 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
9. The last constraint necessary to make the system determined is the speed and the torque of one of the two extreme shafts. For
an input coupled drive (Fig. 11), where the engine is connected to shaft 1, the equations are: ω1 =ωengine and m1 =mengine. In this
way, a system of 8 equations and 8 unknowns is obtained.
The model can then be summarized in its matrix form:
Ω·→
ω = bω
M·→
m = bm:
ð17Þ
The variable efficiencies of the hydraulic machines don't allow the direct solution of Eq. (17). An iterative solution, which
assumes unitary efficiencies at the first iteration, has been set up, with convergence tolerance equal to 0.1%. The flow chart of the
iterative process is shown in Fig. 12.
3. System optimization
The simulation model was coupled with an evolutionary optimization system, which is based on the swarm method, in order to
identify the transmission with the best performance among those satisfying the constraints required by the application.
The optimization process can be generally formulated as follows:
Find x = x1 x2 :: xn½ Š
T
minimizing f xð Þ; subject to the constraints gj xð Þ ≤ 0 j = 1::m and lj xð Þ = 0 j = 1::p:
where:
• x1 x2 :: xn are the free optimization variables (degree of freedom);
• the equality constraints lj(x)=0 j=1..p are the design parameters;
• the inequality constraints gj(x)≤0 j=1..m are the design constraints;
• f(x) is the objective function.
In the following sections, the problem's elements will be presented according to the previous sequence; finally the
optimization technique will be discussed.
3.1. Degrees of freedom
The variables subject to the optimization are:
• the displacements VI and VII;
• the transmission ratios τI and τII;
• The standing transmission ratio T of the planetary gearing;
• The transmission ratio τOut of the gearings (both ordinary and planetary) between the output shaft of the power split
transmission and the wheel axis.
Fig. 13. Overall dimension of the test case vehicle [mm].
1909A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
10. 3.2. Design parameters
The design parameters supplied as input to the optimization procedure are:
• internal combustion engine (ICE) design power (generally close to the best efficiency power);
• design speed of ICE;
• maximum speed of the vehicle;
• maximum wheel pulling force;
• wheel radius.
3.3. Design constraints
The optimization procedure must be forced to satisfy some design and structural constraints. In particular:
• maximum pressure of hydraulic machines: Δp ≤ Δpmax;
• minimum and maximum transmission ratio of the planetary gear: Tmin ≤ T ≤ Tmax;
• maximum and minimum volumes allowed for the units displacement: Vmin ≤ VI and VII ≤ Vmax;
• maximum speed of hydraulic units as a function of displacement: ω'I and ω'I ≤ β(α) ωmax(V).
The maximum speed of the hydraulic units was considered to be a function of the nominal displacement, (ωmax (V)). Because
the maximum speed of the units refers to the full displacement condition, an overspeed factor β (α) was added to model the
increase of the maximum speed in the partial displacement conditions (α b 1).
The constraints were implemented according to penalty functions, which add a quantity proportional to the exceeded distance
from the allowed domain.
3.4. Objective function
The purpose of the optimization was the minimization of fuel consumption caused by transmission losses. Therefore, the
objective function is the integral average loss calculated between the zero speed and maximum design speed of the vehicle:
e xð Þ =
∫
vmax
0
1−ηDrivelineð Þ dv
vmax
: ð18Þ
3.5. Optimization algorithm
Since the object function doesn't have an analytical formulation, direct-search algorithms seem to be suitable for this problem.
Furthermore, the particular form of the objective function, probably with many local minima, suggests the use of evolutionary
algorithms, which are able to reduce the importance of the initial research point and the trapping in local minima far from absolute
minimum.
Table 1
Design data of the test vehicles.
Compact loader Tractor
I.C.E. power 62 kW 180 kW
I.C.E. design speed 2500 rpm 2200 rpm
Wheel radius 0.42 m 0.965 m
Maximum wheel pulling force 28 kN 120 kN
Maximum vehicle speed 16 km h− 1
40 km h−1
Table 2
Optimization constraints.
Symbol Min Max
Hydrostatic system
Unit displacement V 28 cm3
250 cm3
Maximum pressure Δpmax – 400 bar
Maximum unit speed 0 Figs. 14 and 15
Planetary gearing
Standing gear ratio T −1/2 −1/7
1910 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
11. The search algorithms based on swarm (PSO Particle Swarm Optimizer) are stochastic search algorithms based on social
behavior demonstrated by flocks of birds or swarms of insects, in which the interaction between the individual information and
the information sharing with other individuals leads to many evolutionary advantages, such as greater efficiency in finding food.
The most important feature of the particle swarm algorithm is the process that moves the particle of the swarm (initialized in
random positions in the first iteration), between two subsequent iterations. The position of the i-th particle in the space of the
allowable solutions at the n+1 iteration is obtained by summing a displacement d to the position x of the same particle at the n-th
iteration as follows:
x
i
n+1 = x
i
n + d
i
n+1: ð19Þ
The displacement is computed according to the following definition:
d
i
n+1 = wd
i
n + c1rand y
i
n + x
i
n
+ c2rand yn + x
i
n
: ð20Þ
Fig. 14. Maximum speed at full displacement as a function of the unit maximum displacement [17].
Fig. 15. Over speed factor as a function of the actual to maximum displacement [19].
1911A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
12. The displacement includes three terms, which model the prime basis of the social behaviors:
• the first term models the resistance to changes: an individual tends to repeat its behavior and maintain its opinions even if new
environmental changes suggest to modify them. This term is ruled by the inertial coefficient w, which multiplies the
displacement at the previous iteration;
• the second one represents the tendency of any singular individual to move toward the position of best fitness, according to its
own experience. The position yn
i
is, in fact, defined as the best position discovered by the i-th particle from the beginning of the
optimization to the current iteration. This component is weighted by the so-called “self confidence” coefficient c1 and the
uniformly distributed random variable rand that can take any value between 0 and 1;
• the third one models the interaction between individuals such as knowledge sharing and emulations. The goal of this part of the
displacement is to move toward the position yn, which is the position of best fitness ever discovered by the swarm. This
component is weighted by the so called “swarm confidence” coefficient c2 and the random variable rand.
In the current optimization values of 0.6, 1.5 and 1.5 respectively for the inertial coefficient w, c1 and c2. The convergence
criterion used was based on the mean dispersion of the swarm, assuming the criterion was fulfilled when at least 80% of the
particles were collected inside 0.05% of the design space centered around the best known solution yn.
The optimizer used in this work, originally presented by Shu-Kai S. Fan et al. [15], combines the classical formulation of PSO
with the Nelder–Mead algorithm [18]. This formulation improves the efficiency of local convergence, keeping the research
capabilities of the algorithm unchanged.
Fig. 16. Swarm dispersion as function of the optimizer iterations; (a) compact loader, (b) agricultural tractor.
1912 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
13. 4. Application of the optimization procedure
In order to test the optimization procedure, two different work vehicles were considered: a compact loader and a high power
tractor. The dimensions and the design data of the two vehicles are shown respectively in Fig. 13 and Table 1. In Table 2 the design
constraints are summarized. The maximum unit speed is calculated (section 3.3) as the product of the maximum speed and the
over speed factor, respectively represented in Figs. 14 and 15. The maximum speed at full displacement was defined as a function
of the unit size and could be well interpolated as a linear trend in double logarithmic axes, with smaller units characterized by
higher velocities (Fig. 14). The over speed factor is instead described as a function of the actual to maximum displacement and
Fig. 17. Best fitness as function of the optimizer iterations; (a) compact loader, (b) agricultural tractor.
Table 3
Optimization results for the compact loader
test case.
T −0.44
VI 30 cm3
VII 83 cm3
τI 1.66
τII 2.35
τout 17.15
ηmean 0.785
1913A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
14. expresses the capability of the unit to withstand higher velocity at partial displacement (Fig. 15). The used data were derived from
online catalogs for axial piston machines [17,19].
The different characteristics of the vehicles suggested two different transmission configurations.
The small size and power of the compact loader indicated an input coupled solution, which allows to achieve better
performance with smaller hydrostatic units than with the output coupled configuration [7]. For the agricultural tractor, instead, an
output coupled transmission was considered, which leads to higher performance, even with larger size of the hydrostatic units.
However, to contain the value of the displacements, given the high value of the maximum force exerted by the tractor, a two-speed
gearbox with a transmission ratio equal to 4 was placed downstream from the CVT transmission. The speed change point was
chosen where the transmission efficiency line in the first gear crossed the transmission efficiency line in the second gear.
η
1st gear
DriveLine vchange
= η
2nd gear
DriveLine vchange
: ð21Þ
The objective function was then rewritten for this case as:
e xð Þ =
∫ vchange
0
1−η1st gear
Driveline
dv + ∫ vmax
vchange
1−η2nd gear
Driveline
dv
vmax
: ð22Þ
Fig. 18. Overall efficiency and hydrostatic path efficiency for the compact loader.
Fig. 19. Unit's speed and speed limits for the compact loader.
1914 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
15. 4.1. Results
4.1.1. Optimizator performance
The optimization procedure took 6.8103
s and 1.1104
s for the compact loader and the agricultural tractor respectively using
parallel computing on a 2 processor dual core AMD Opteron 265 computer. The convergence history was monitored by
considering both the objective function value and the mean dispersion of the swarm on the design space. As previously introduced,
the convergence of the algorithm was defined on the basis of the mean normalized distance from the current best position of the
nearest 80% of the swarm. Fig. 16 describes the swarm dispersion by means of three different measures:
• the average distance from the best position, calculated on the overall swarm (r100%);
• the average distance from the best position considering only the nearest 80% of the swarm particles, i.e. the convergence control
variable (r80%);
• the average distance from the best position considering only the nearest 50% of the swarm particles (r50%).
In both the cases, the three lines move parallel to each other on the logarithmic scale. This proves the capability of the algorithm
to balance between the refinement of the search near the current actual optimum and the scouting of the design space in order to
avoid early convergence to a local optimum. Half of the swarm, in fact, searches in the 10% of the design space near the current
Fig. 20. Unit's displacement as a function of the vehicle ground speed for the compact loader.
Fig. 21. HST pressure as a function of the vehicle ground speed for the compact loader.
1915A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
16. optimum for most of the convergence history (r50% b0.1), while the significant difference between the r80% and r100% demonstrates
that the farthest 20% of the particles are spread on the design space even in the late part of the convergence.
Fig. 17 reports the trend of the best efficiency as a function of the iteration number for the two test cases. The highly
discontinuous trend shows that most of the improvements are due to a radical change in the transmission configuration instead of
through the local adjustment of the current optimum. This could be related to the positive contribution of the diverging particles.
The discontinuous movements of the optimum configuration as the iteration increases could be clearly seen comparing Figs. 16
and 17: the steep increase of the best fitness is related to a sudden expansion of the average swarm radius, proving the
repositioning of the optimum configuration used as the origin of the radial measurements.
The optimizer was capable of avoiding the low-fitness local optimum and was able to converge toward an acceptable high-
fitness optimum, for both cases.
4.1.2. Test case 1: compact loader
The optimum design of the compact loader is reported in Table 3, while Figs. 16 to 19 report the behavior of the most important
variables of the power split transmission.
In Fig. 18, the overall efficiency of the transmission and the efficiency of HST are reported. The former shows the typical trend
for input coupled transmissions: the recirculation of power between mechanical and hydraulic paths leads to a sudden decrease of
performance for speeds lower than the full mechanical point; at speeds higher than the full mechanical point the overall efficiency
is close to the CVT hydraulic efficiency as the power transferred by the hydraulic path increases. The mean overall efficiency of the
optimum transmission in the range 0–16 km/h is 0.785, which could be considered a good result for such a small and compact
solution.
Fig. 19 shows the rotational speed of the two hydraulic units compared to the maximum allowable speed for the considered
displacement. The displacement of the hydrostatic units is instead reported in Fig. 20, while the differential pressure inside the
hydrostatic system is reported in Fig. 21.
4.1.3. Test case 2: Agricultural tractor
The optimum design parameters are presented in Table 4.
Fig. 22 shows the efficiency of the overall transmission and of the hydrostatic CVT element for the design velocity range. The
initial choice of a gear ratio of 4 seems to be appropriate in terms of efficiency because the transmission presents the highest
Table 4
Optimization results for the agricultural
tractor.
T −0.29
VI 156 cm3
VII 244 cm3
τI 3.82
τII 3.97
Fig. 22. Overall efficiency and hydrostatic path efficiency for the agricultural tractor.
1916 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
17. efficiency in the velocity ranges typical of the most power expensive condition: in field work and street transport. In fact, the
transmission shows efficiency higher than 85% in the low velocity range (4–10 km/h), which corresponds to the typical range of
field working velocity, while the maximum efficiency of the high gear is instead compatible with the street transport condition.
The mean overall efficiency of the transmission is 84%, which is notably higher than the standard proposed by Renius for CVT
hydraulic transmission [3].
As for the previous test case, Figs. 23–25 complete the description of the system behavior, giving the unit's speed, displacement
and the differential pressure of the HST system.
5. Conclusions
The advantage of the continuous speed variation of the power-split drives is counterbalanced by a reduced efficiency, caused by
the double energy conversion taking place in the hydrostatic transmission. Therefore, the design of the power split drive must be
carefully studied.
In this paper, the design is treated as an optimization problem, where the objective function to be minimized is the total loss of
the transmission, and the free variables are the displacements of the hydraulic machines and the gear ratios of the ordinary and
planetary gearings.
Fig. 23. Unit's speed and speed limits for the agricultural tractor.
Fig. 24. Unit's displacement as a function of the vehicle ground speed for the agricultural tractor.
1917A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
18. An automatic procedure, made up by a steady state simulator of the driveline and an evolutionary optimizer, was set up to solve
this problem. The steady simulator takes into account the losses of the hydraulic units, which heavily influence the driveline
efficiency, and the losses of the other mechanical components.
A “direct search” algorithm based on the swarm method was used as the optimizer, which showed a good speed convergence
and the ability to overcome local minima.
The proposed approach offers significant advantages over traditional design methods: the procedure does not depend on
experience and previous knowledge because no assumption had to be made on the component's sizing; the optimality of the
output is based on the implemented search algorithm while the quality of the classical designs depends strongly on the designer's
experience. Furthermore the procedure can handle more complex constraint formulation than traditional design methods and
verify them for all the working conditions.
The procedure was then tested on two heavy duty vehicles, which were chosen to be very different in terms of power, size and
velocity range: a compact loader with a nominal power of 62 kW, and an agricultural tractor of 180 kW. The procedure
demonstrated to be capable of handling the optimized design of both test cases, fulfilling all the design constraints and obtaining
high efficiency drivelines.
The procedure could also be further developed in order to be applied in more complex power split configurations, such as the
“dual stage” and the compound solutions.
Nomenclature
m torque [Nm]
n iteration [–]
p pressure [Pa]
v velocity [m s−1
]
z gear tooth number [–]
M transmission torque matrix [–]
P power [W]
T=−zs/zr
standing gear ratio of the planetary gear [–]
V maximum unit displacement [m3
]
Greek letters
α actual to maximum displacement ratio [–]
ηv volumetric efficiency [–]
ηhym hydro mechanical efficiency [–]
τ gear ratio [–]
τout gear ratio of gearbox between power split transmission and axle [–]
ω rotational speed [rad s−1
]
Fig. 25. HST pressure as a function of the vehicle ground speed for the agricultural tractor.
1918 A. Macor, A. Rossetti / Mechanism and Machine Theory 46 (2011) 1901–1919
19. χ non dimensional penalty coefficient for unit efficiency calculation [–]
Ω transmission velocity matrix [–]
Subscript and Superscripts
I hydrostatic transmission element inlet shaft
II hydrostatic transmission element outlet shaft
rif condition of unit maximum efficiency
c planetary gear, carrier shaft
s planetary gear, sun shaft
r planetary gear, ring shaft
′ unit shaft
Acknowledgment
The results presented in the paper were obtained as part of the research program “Studio di trasmissioni power-split per
trattrici agricole” of the PRIN 2007 (Programmi di Ricerca di Interesse Nazionale — Research Programs of National Interest 2007)
funded by Ministero dell'Istruzione, dell'Università e della Ricerca (Ministry of Education, University and Research) of Italian
Republic.
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