In a conventional direct torque control(CDTC) of the induction motor drive, the electromagnetic torque and the stator flux are characterized by high ripples. In order to reduce the undesired ripples, several methods a...In a conventional direct torque control(CDTC) of the induction motor drive, the electromagnetic torque and the stator flux are characterized by high ripples. In order to reduce the undesired ripples, several methods are used in the literature. Nevertheless,these methods increase the algorithm complexity and dependency on the machine parameters such as the space vector modulation(SVM). The fuzzy logic control method is utilized in this work to decrease these ripples. Moreover, to eliminate the mechanical sensor the extended kalman filter(EKF) is used, in order to reduce the cost of the system and the rate of maintenance. Furthermore, in the domain of controlling the real-time induction motor drives, two principal digital devices are used such as the hardware(FPGA) and the digital signal processing(DSP). The latter is a software solution featured by a sequential processing that increases the execution time. However, the FPGA is featured by a high processing speed because of its parallel processing. Therefore, using the FPGA it is possible to implement complex algorithms with low execution time and to enhance the control bandwidth. The large bandwidth is the key issue to increase the system performances. This paper presents the interest of utilizing the FPGAs to implement complex control algorithms of electrical systems in real time. The suggested sensorless direct torque control using the fuzzy logic(DTFC) of an induction motor is successfully designed and implemented on an FPGA Virtex 5 using xilinx system generator. The simulation and implementation results show proposed approach s performances in terms of ripples, stator current harmonic waves, execution time, and short design time.展开更多
Constructive nonlinear control design has undergone rapid and significant progress over the last three decades. In this paper, a review of recent results in this important field is presented with a focus on interdisci...Constructive nonlinear control design has undergone rapid and significant progress over the last three decades. In this paper, a review of recent results in this important field is presented with a focus on interdisciplinary topics at the interface of control,computing and communications. In particular, it is shown that the nonlinear small-gain theory provides a unified framework for solving problems of quantized feedback stabilization and event-triggered control for nonlinear systems. Some open questions in quantized and networked nonlinear control systems are discussed.展开更多
In this study,a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable.Different materials were s...In this study,a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable.Different materials were studied as landfill cover system in lab-scale columns：mechanical–biological pretreated municipal solid waste（MBP）;mechanical–biological pretreated biowaste（PB）;fine（PBSf）and coarse（PBSc）mechanical–biological pretreated mixtures of biowaste and sewage sludge,and natural soil（NS）.The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested,even coupled with activated carbon membranes.Concentrations of CO2,CH4,O2,N2,H2S and mercaptans were analysed at different depths along the columns.Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate（MOR）.The highest maximum and mean MOR were observed for MBP（17.2 g CH4/m^2/hr and 10.3 g CH4/m^2/hr,respectively）.Similar values were obtained with PB and PBSc.The lowest values of MOR were obtained for NS（6.7 g CH4/m^2/hr）and PBSf（3.6 g CH4/m^2/hr）,which may be due to their low organic content and void index,respectively.Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process：MBP coupled with 220 g/m^2and 360 g/m^2membranes gave maximum MOR of 16.5 g CH4/m^2/hr and 17.4 g CH4/m^2/hr,respectively.Activated carbon membranes proved to be very effective on H2S adsorption.Furthermore,carbonyl sulphide,ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials.展开更多
Morphological variation based on eight measured and four derived traits was studied to establish whether there was significant variation between populations and to identify the influence of the altitude on morphologic...Morphological variation based on eight measured and four derived traits was studied to establish whether there was significant variation between populations and to identify the influence of the altitude on morphological differentiation among 44 natural stands of common oak（Quercus robur L.） in Bosnia and Herzegovina,ranging from 82 to 860 m.The results point to significant intra-and inter-population differences.Elevation-related variation is less pronounced and determined largely by microclimatic factors.The results could provide management strategies for species reintroduction in the study area.There are no differences in leaf morphology between the different branches of individual trees.However,there are important variations between the altitudinal groups and closely linked to environmental factors in all traits.An important recommendation is to use seeds from oak with attention to their altitudinal origin.展开更多
The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULF)and the purely turbulent component(PTC),and the contributions are analyzed separately by theoretical ex...The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULF)and the purely turbulent component(PTC),and the contributions are analyzed separately by theoretical experiments.It is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state flows.The universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is examined.It is shown that the time constant is related to the turbulence's frozen time.Finally,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.展开更多
In this paper, the output consensus problem of general heterogeneous nonlinear multi-agent systems subject to different disturbances is considered. A kind of Takagi-Sukeno fuzzy modeling method is used to describe the...In this paper, the output consensus problem of general heterogeneous nonlinear multi-agent systems subject to different disturbances is considered. A kind of Takagi-Sukeno fuzzy modeling method is used to describe the nonlinear agents' dynamics. Based on the model, a distributed fuzzy observer and controller are designed based on parallel distributed compensation scheme and internal reference models such that the heterogeneous nonlinear multi-agent systems can achieve output consensus. Then a necessary and sufficient condition is presented for the output consensus problem. And it is shown that the consensus trajectory of the global fuzzy model is determined by the network topology and the initial states of the internal reference models. Finally, some simulations are given to illustrate and verify the effectiveness of the proposed scheme.展开更多
As human beings,people coordinate movements and interact with the environment through sensory information and motor adaptation in the daily lives.Many characteristics of these interactions can be studied using optimiz...As human beings,people coordinate movements and interact with the environment through sensory information and motor adaptation in the daily lives.Many characteristics of these interactions can be studied using optimization-based models,which assume that the precise knowledge of both the sensorimotor system and its interactive environment is available for the central nervous system(CNS).However,both static and dynamic uncertainties occur inevitably in the daily movements.When these uncertainties are taken into consideration,the previously developed models based on optimization theory may fail to explain how the CNS can still coordinate human movements which are also robust with respect to the uncertainties.In order to address this problem,this paper presents a novel computational mechanism for sensorimotor control from a perspective of robust adaptive dynamic programming(RADP).Sharing some essential features of reinforcement learning,which was originally observed from mammals,the RADP model for sensorimotor control suggests that,instead of identifying the system dynamics of both the motor system and the environment,the CNS computes iteratively a robust optimal control policy using the real-time sensory data.An online learning algorithm is provided in this paper,with rigorous convergence and stability analysis.Then,it is applied to simulate several experiments reported from the past literature.By comparing the proposed numerical results with these experimentally observed data,the authors show that the proposed model can reproduce movement trajectories which are consistent with experimental observations.In addition,the RADP theory provides a unified framework that connects optimality and robustness properties in the sensorimotor system.展开更多
This study examines the effect of key big data analytics capabilities(data,skills,technology,and culture)on innovation performance and business performance.Data were gathered from 91 companies and analyzed to determin...This study examines the effect of key big data analytics capabilities(data,skills,technology,and culture)on innovation performance and business performance.Data were gathered from 91 companies and analyzed to determine correlations in the proposed model.The results find that big data analytics capabilities(BDAC)partially mediate the effect between innovative performance and business performance.Further,as a company’s performance is a multidimensional element,was necessary to analyze more than one attribute to evaluate the relationship with BDAC through a canonical correlation analysis.The results in this sense reveal that the four big data capabilities increase the growth of sales,revenue,the number of workers,the net profit margin,innovation management,the development of new products and services,and the adoption of new information technologies.展开更多
文摘In a conventional direct torque control(CDTC) of the induction motor drive, the electromagnetic torque and the stator flux are characterized by high ripples. In order to reduce the undesired ripples, several methods are used in the literature. Nevertheless,these methods increase the algorithm complexity and dependency on the machine parameters such as the space vector modulation(SVM). The fuzzy logic control method is utilized in this work to decrease these ripples. Moreover, to eliminate the mechanical sensor the extended kalman filter(EKF) is used, in order to reduce the cost of the system and the rate of maintenance. Furthermore, in the domain of controlling the real-time induction motor drives, two principal digital devices are used such as the hardware(FPGA) and the digital signal processing(DSP). The latter is a software solution featured by a sequential processing that increases the execution time. However, the FPGA is featured by a high processing speed because of its parallel processing. Therefore, using the FPGA it is possible to implement complex algorithms with low execution time and to enhance the control bandwidth. The large bandwidth is the key issue to increase the system performances. This paper presents the interest of utilizing the FPGAs to implement complex control algorithms of electrical systems in real time. The suggested sensorless direct torque control using the fuzzy logic(DTFC) of an induction motor is successfully designed and implemented on an FPGA Virtex 5 using xilinx system generator. The simulation and implementation results show proposed approach s performances in terms of ripples, stator current harmonic waves, execution time, and short design time.
基金supported by National Natural Science Foundation of China(No.61374042)the Fundamental Research Funds for the Central Universities in China(No.N130108001)
文摘Constructive nonlinear control design has undergone rapid and significant progress over the last three decades. In this paper, a review of recent results in this important field is presented with a focus on interdisciplinary topics at the interface of control,computing and communications. In particular, it is shown that the nonlinear small-gain theory provides a unified framework for solving problems of quantized feedback stabilization and event-triggered control for nonlinear systems. Some open questions in quantized and networked nonlinear control systems are discussed.
文摘In this study,a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable.Different materials were studied as landfill cover system in lab-scale columns：mechanical–biological pretreated municipal solid waste（MBP）;mechanical–biological pretreated biowaste（PB）;fine（PBSf）and coarse（PBSc）mechanical–biological pretreated mixtures of biowaste and sewage sludge,and natural soil（NS）.The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested,even coupled with activated carbon membranes.Concentrations of CO2,CH4,O2,N2,H2S and mercaptans were analysed at different depths along the columns.Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate（MOR）.The highest maximum and mean MOR were observed for MBP（17.2 g CH4/m^2/hr and 10.3 g CH4/m^2/hr,respectively）.Similar values were obtained with PB and PBSc.The lowest values of MOR were obtained for NS（6.7 g CH4/m^2/hr）and PBSf（3.6 g CH4/m^2/hr）,which may be due to their low organic content and void index,respectively.Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process：MBP coupled with 220 g/m^2and 360 g/m^2membranes gave maximum MOR of 16.5 g CH4/m^2/hr and 17.4 g CH4/m^2/hr,respectively.Activated carbon membranes proved to be very effective on H2S adsorption.Furthermore,carbonyl sulphide,ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials.
基金financially supported by the Cantonal Ministry of Education and Science,Sarajevo Canton,Agreement No.11-14-20059.1/07 of 27.12.2007
文摘Morphological variation based on eight measured and four derived traits was studied to establish whether there was significant variation between populations and to identify the influence of the altitude on morphological differentiation among 44 natural stands of common oak（Quercus robur L.） in Bosnia and Herzegovina,ranging from 82 to 860 m.The results point to significant intra-and inter-population differences.Elevation-related variation is less pronounced and determined largely by microclimatic factors.The results could provide management strategies for species reintroduction in the study area.There are no differences in leaf morphology between the different branches of individual trees.However,there are important variations between the altitudinal groups and closely linked to environmental factors in all traits.An important recommendation is to use seeds from oak with attention to their altitudinal origin.
文摘The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULF)and the purely turbulent component(PTC),and the contributions are analyzed separately by theoretical experiments.It is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state flows.The universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is examined.It is shown that the time constant is related to the turbulence's frozen time.Finally,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.61375105 and 61403334Chinese Postdoctoral Science Fundation under Grant No.2015M581318
文摘In this paper, the output consensus problem of general heterogeneous nonlinear multi-agent systems subject to different disturbances is considered. A kind of Takagi-Sukeno fuzzy modeling method is used to describe the nonlinear agents' dynamics. Based on the model, a distributed fuzzy observer and controller are designed based on parallel distributed compensation scheme and internal reference models such that the heterogeneous nonlinear multi-agent systems can achieve output consensus. Then a necessary and sufficient condition is presented for the output consensus problem. And it is shown that the consensus trajectory of the global fuzzy model is determined by the network topology and the initial states of the internal reference models. Finally, some simulations are given to illustrate and verify the effectiveness of the proposed scheme.
基金supported in part by the US National Science Foundation Grant Nos.ECCS-1101401 and ECCS-1230040
文摘As human beings,people coordinate movements and interact with the environment through sensory information and motor adaptation in the daily lives.Many characteristics of these interactions can be studied using optimization-based models,which assume that the precise knowledge of both the sensorimotor system and its interactive environment is available for the central nervous system(CNS).However,both static and dynamic uncertainties occur inevitably in the daily movements.When these uncertainties are taken into consideration,the previously developed models based on optimization theory may fail to explain how the CNS can still coordinate human movements which are also robust with respect to the uncertainties.In order to address this problem,this paper presents a novel computational mechanism for sensorimotor control from a perspective of robust adaptive dynamic programming(RADP).Sharing some essential features of reinforcement learning,which was originally observed from mammals,the RADP model for sensorimotor control suggests that,instead of identifying the system dynamics of both the motor system and the environment,the CNS computes iteratively a robust optimal control policy using the real-time sensory data.An online learning algorithm is provided in this paper,with rigorous convergence and stability analysis.Then,it is applied to simulate several experiments reported from the past literature.By comparing the proposed numerical results with these experimentally observed data,the authors show that the proposed model can reproduce movement trajectories which are consistent with experimental observations.In addition,the RADP theory provides a unified framework that connects optimality and robustness properties in the sensorimotor system.
基金financially supported by the Spanish State Research Agency(Agencia Estatal de Investigación)of the Spanish Ministry of Science and Innovation(MCIN/AEI/10.13039/501100011033)via the project‘Speeding up the transition towards resilient circular economy networks:forecasting,inventory and production control,reverse logistics and supply chain dynamics’(SPUR,grant ref.PID2020-117021GB-I00)+1 种基金Author Omar León:contract financed under Royal Decree 289/2021,of April 20,Ministry of Universities,for the requalification of the Spanish university system and Order UNI/551/2021of May 26.Maria Zambrano Modality,Project Ref.MU-21-UP2021-030 AX492867.
文摘This study examines the effect of key big data analytics capabilities(data,skills,technology,and culture)on innovation performance and business performance.Data were gathered from 91 companies and analyzed to determine correlations in the proposed model.The results find that big data analytics capabilities(BDAC)partially mediate the effect between innovative performance and business performance.Further,as a company’s performance is a multidimensional element,was necessary to analyze more than one attribute to evaluate the relationship with BDAC through a canonical correlation analysis.The results in this sense reveal that the four big data capabilities increase the growth of sales,revenue,the number of workers,the net profit margin,innovation management,the development of new products and services,and the adoption of new information technologies.
