In this paper, a two species predator-prey model is developed where prey is affected by over-harvesting and drought and predator is affected by drought. The intention is to investigate the impact of over-harvesting an...In this paper, a two species predator-prey model is developed where prey is affected by over-harvesting and drought and predator is affected by drought. The intention is to investigate the impact of over-harvesting and drought on predator-prey system, and suggest control strategies to alleviate the problem of loss of prey and predator species due to over-harvesting and drought. The control strategies suggested are creation of reserve areas with restriction of harvesting for controlling over-harvesting and construction of dams for mitigating drought effects. The results obtained from theoretical and numerical simulation of the predator-prey model with harvesting and drought without control strategies showed that, both harvesting and drought affect the predator-prey population negatively. However, the results obtained from numerical simulations of the model with control measures showed that, the use of control strategies one at a time encourages the increase of the prey and predator species to the optimal population size. Furthermore, the best result is obtained when control strategies, creation of reserve areas with restriction of harvesting and construction of dams are applied simultaneously.展开更多
In this paper, astochastic predator-prey systems with nonlinear harvesting and impulsive effect are investigated. Firstly, we show the existence and uniqueness of the global positive solution of the system. Secondly, ...In this paper, astochastic predator-prey systems with nonlinear harvesting and impulsive effect are investigated. Firstly, we show the existence and uniqueness of the global positive solution of the system. Secondly, by constructing appropriate Lyapunov function and using comparison theorem with an impulsive differential equation, we study that a positive periodic solution exists. Thirdly, we prove that system is globally attractive. Finally, numerical simulations are presented to show the feasibility of the obtained results.展开更多
串联同步开关电感(Series Synchronous Switch Harvesting on Inductor,S-SSHI)电路输出功率高整流电压范围窄,而同步电荷提取(Synchronous Electric Charge Extraction,SECE)电路则输出功率低整流电压范围宽。提出了一种基于S-SSHI和S...串联同步开关电感(Series Synchronous Switch Harvesting on Inductor,S-SSHI)电路输出功率高整流电压范围窄,而同步电荷提取(Synchronous Electric Charge Extraction,SECE)电路则输出功率低整流电压范围宽。提出了一种基于S-SSHI和SECE混合的压电阵列能量俘获接口电路,以实现整流器峰值输出功率和最佳整流电压范围之间的平衡。所提出的电路去除了整流桥结构,而采用简单的无源峰值检测器设计,且可以在任意相位差(0~2π)下从多个压电换能器中提取能量。仿真和实验结果表明,所提出的电路具有较高的输出功率和较宽的整流电压范围,与多输入全桥整流器相比,最大输出功率提升了3.04倍。展开更多
In this paper, we propose and analyze a mathematical model to study the dynamics of a fishery resource system with stage structure in an aquatic environment that consists of two zones namely unreserved zone (fishing p...In this paper, we propose and analyze a mathematical model to study the dynamics of a fishery resource system with stage structure in an aquatic environment that consists of two zones namely unreserved zone (fishing permitted) and reserved zone (fishing is strictly prohibited). In this model we introduce a stage structure in which predators are split into two kinds as immature predators and mature predators. It is assumed that immature predators cannot catch the prey and their foods are given by their parents (mature predators). It is also assumed that the fishing of immature predators prohibited in the unreserved zone and predator species are not allowed to enter inside the reserved zone. The local and global stability analysis has been specified. Biological and Bionomical equilibriums of the system are derived. Mathematical formulation of the optimal harvesting policy is given and its solution is derived in the equilibrium case by using Pontryagin’s maximum principle.展开更多
To improve piezoelectric harvesting efficiency of Cymbal, optimization design of Cymbal parameters was studied with the method of Taguchi’s orthogonal experiment. The effective factors of piezoelectric harvesting pro...To improve piezoelectric harvesting efficiency of Cymbal, optimization design of Cymbal parameters was studied with the method of Taguchi’s orthogonal experiment. The effective factors of piezoelectric harvesting property were firstly analyzed. The orthogonal experiment schedule was then designed. The finite element model of Cymbal was built via ASPL tool in ANSYS software and static analysis was done. The experimental results were gotten with developed program. The optimization level of each factor was gained. Under the synthetical optimization level of each design factor, the piezoelectric analysis was tested and the open voltage of 236.476 V was revealed with improving 35.73% than the maximum voltage of 174.228 V in the orthogonal experiment. The average voltage of 229.98 V was measured with the manufactured optimized Cymbal structure design. The relative error was 2.54% between simulation and measured data. It indicated that the optimization design schedule was reasonable. Cymbal harvester with the optimized parameters could scavenge larger voltage.展开更多
To effectively harvest vibration energy from pavement without affecting driving comfort and safety, parameter optimization was done with the orthogonal experiment design and the finite element analysis. L16(44) Taguch...To effectively harvest vibration energy from pavement without affecting driving comfort and safety, parameter optimization was done with the orthogonal experiment design and the finite element analysis. L16(44) Taguchi’s orthogonal experiments were carried out with planted depth, PZT material, PZT diameter and thickness as optimization parameters and with open voltage and pavement displacement as optimization objectives. The experiment results were obtained via the finite element method. By using range analysis method, the dominance degree of the influencing factors and the optimum condition was obtained for the two objectives, respectively. Further, the multi-objective optimization was performed based on a weight grade method. The combined optimum conditions in order of their dominance degree are PZT diameter 35 mm, PZT thickness 6 mm, planted depth 50 mm and material PZT4. The validity of optimization scheme was confirmed.展开更多
Ideal point method is one of the methods to solve multi-objective problem. It is applied to forest harvest regu-lation, and showed very good results by analyzing changes of quantitative indexes of forest resource stru...Ideal point method is one of the methods to solve multi-objective problem. It is applied to forest harvest regu-lation, and showed very good results by analyzing changes of quantitative indexes of forest resource structure before andafter the regulation. This method can be applied as one of the mathematical tools in forest harvest regulation.展开更多
文摘In this paper, a two species predator-prey model is developed where prey is affected by over-harvesting and drought and predator is affected by drought. The intention is to investigate the impact of over-harvesting and drought on predator-prey system, and suggest control strategies to alleviate the problem of loss of prey and predator species due to over-harvesting and drought. The control strategies suggested are creation of reserve areas with restriction of harvesting for controlling over-harvesting and construction of dams for mitigating drought effects. The results obtained from theoretical and numerical simulation of the predator-prey model with harvesting and drought without control strategies showed that, both harvesting and drought affect the predator-prey population negatively. However, the results obtained from numerical simulations of the model with control measures showed that, the use of control strategies one at a time encourages the increase of the prey and predator species to the optimal population size. Furthermore, the best result is obtained when control strategies, creation of reserve areas with restriction of harvesting and construction of dams are applied simultaneously.
文摘In this paper, astochastic predator-prey systems with nonlinear harvesting and impulsive effect are investigated. Firstly, we show the existence and uniqueness of the global positive solution of the system. Secondly, by constructing appropriate Lyapunov function and using comparison theorem with an impulsive differential equation, we study that a positive periodic solution exists. Thirdly, we prove that system is globally attractive. Finally, numerical simulations are presented to show the feasibility of the obtained results.
文摘串联同步开关电感(Series Synchronous Switch Harvesting on Inductor,S-SSHI)电路输出功率高整流电压范围窄,而同步电荷提取(Synchronous Electric Charge Extraction,SECE)电路则输出功率低整流电压范围宽。提出了一种基于S-SSHI和SECE混合的压电阵列能量俘获接口电路,以实现整流器峰值输出功率和最佳整流电压范围之间的平衡。所提出的电路去除了整流桥结构,而采用简单的无源峰值检测器设计,且可以在任意相位差(0~2π)下从多个压电换能器中提取能量。仿真和实验结果表明,所提出的电路具有较高的输出功率和较宽的整流电压范围,与多输入全桥整流器相比,最大输出功率提升了3.04倍。
文摘In this paper, we propose and analyze a mathematical model to study the dynamics of a fishery resource system with stage structure in an aquatic environment that consists of two zones namely unreserved zone (fishing permitted) and reserved zone (fishing is strictly prohibited). In this model we introduce a stage structure in which predators are split into two kinds as immature predators and mature predators. It is assumed that immature predators cannot catch the prey and their foods are given by their parents (mature predators). It is also assumed that the fishing of immature predators prohibited in the unreserved zone and predator species are not allowed to enter inside the reserved zone. The local and global stability analysis has been specified. Biological and Bionomical equilibriums of the system are derived. Mathematical formulation of the optimal harvesting policy is given and its solution is derived in the equilibrium case by using Pontryagin’s maximum principle.
文摘To improve piezoelectric harvesting efficiency of Cymbal, optimization design of Cymbal parameters was studied with the method of Taguchi’s orthogonal experiment. The effective factors of piezoelectric harvesting property were firstly analyzed. The orthogonal experiment schedule was then designed. The finite element model of Cymbal was built via ASPL tool in ANSYS software and static analysis was done. The experimental results were gotten with developed program. The optimization level of each factor was gained. Under the synthetical optimization level of each design factor, the piezoelectric analysis was tested and the open voltage of 236.476 V was revealed with improving 35.73% than the maximum voltage of 174.228 V in the orthogonal experiment. The average voltage of 229.98 V was measured with the manufactured optimized Cymbal structure design. The relative error was 2.54% between simulation and measured data. It indicated that the optimization design schedule was reasonable. Cymbal harvester with the optimized parameters could scavenge larger voltage.
文摘To effectively harvest vibration energy from pavement without affecting driving comfort and safety, parameter optimization was done with the orthogonal experiment design and the finite element analysis. L16(44) Taguchi’s orthogonal experiments were carried out with planted depth, PZT material, PZT diameter and thickness as optimization parameters and with open voltage and pavement displacement as optimization objectives. The experiment results were obtained via the finite element method. By using range analysis method, the dominance degree of the influencing factors and the optimum condition was obtained for the two objectives, respectively. Further, the multi-objective optimization was performed based on a weight grade method. The combined optimum conditions in order of their dominance degree are PZT diameter 35 mm, PZT thickness 6 mm, planted depth 50 mm and material PZT4. The validity of optimization scheme was confirmed.
文摘Ideal point method is one of the methods to solve multi-objective problem. It is applied to forest harvest regu-lation, and showed very good results by analyzing changes of quantitative indexes of forest resource structure before andafter the regulation. This method can be applied as one of the mathematical tools in forest harvest regulation.
