The cold chain in the production area of fruits and vegetables is the primary link to reduce product loss and improve product quality,but it is also a weak link.With the application of big data technology in cold chai...The cold chain in the production area of fruits and vegetables is the primary link to reduce product loss and improve product quality,but it is also a weak link.With the application of big data technology in cold chain logistics,intelligent devices,and technologies have become important carriers for improving the efficiency of cold chain logistics in fruit and vegetable production areas,extending the shelf life of fruits and vegetables,and reducing fruit and vegetable losses.They have many advantages in fruit and vegetable pre-cooling,sorting and packaging,testing,warehousing,transportation,and other aspects.This article summarizes the rapidly developing and widely used intelligent technologies at home and abroad in recent years,including automated guided vehicle intelligent handling based on electromagnetic or optical technology,intelligent sorting based on sensors,electronic optics,and other technologies,intelligent detection based on computer vision technology,intelligent transportation based on perspective imaging technology,etc.It analyses and studies the innovative research and achievements of various scholars in applying intelligent technology in fruit and vegetable cold chain storage,sorting,detection,transportation,and other links,and improves the efficiency of fruit and vegetable cold chain logistics.However,applying intelligent technology in fruit and vegetable cold chain logistics also faces many problems.The challenges of high cost,difficulty in technological integration,and talent shortages have limited the development of intelligent technology in the field of fruit and vegetable cold chains.To solve the current problems,it is proposed that costs be controlled through independent research and development,technological innovation,and other means to lower the entry threshold for small enterprises.Strengthen integrating intelligent technology and cold chain logistics systems to improve data security and system compatibility.At the same time,the government should introduce relevant policies,provide necessary financial support,and establish talent training mechanisms.Accelerate the development and improvement of intelligent technology standards in the field of cold chain logistics.Through technological innovation,cost control,talent cultivation,and policy guidance,we aim to promote the upgrading of the agricultural industry and provide ideas for improving the quality and efficiency of fruit and vegetable cold chain logistics.展开更多
目的:观察肾素前体(prorenin)能否激活体外培养的人肾系膜细胞(HRMCs)膜表面的肾素(前体)受体[(P)RR],从而活化细胞外信号调节激酶1/2(ERK1/2)信号通路。方法:体外培养HRMCs。以血管紧张素Ⅱ1型受体(AT1)阻断剂olmsartan和血管紧张素Ⅱ...目的:观察肾素前体(prorenin)能否激活体外培养的人肾系膜细胞(HRMCs)膜表面的肾素(前体)受体[(P)RR],从而活化细胞外信号调节激酶1/2(ERK1/2)信号通路。方法:体外培养HRMCs。以血管紧张素Ⅱ1型受体(AT1)阻断剂olmsartan和血管紧张素Ⅱ2型受体(AT2)阻断剂PD123319孵育细胞,再以prorenin刺激细胞,并用ERK1/2抑制剂PD98059和HRP(handle region peptide)干预。用免疫蛋白印迹方法(Western blotting)和酶标记免疫吸附测定方法(ELISA)测定目的蛋白水平,以逆转录聚合酶链反应(RT-PCR)方法测定mRNA水平。结果:Prorenin作用于体外培养的HRMCs后,在阻断AT1和AT2受体时,能激活(P)RR使ERK1/2磷酸化增强、转化生长因子(TGF-β)水平增高。这种ERK1/2信号通路的激活是(P)RR激活后效应,并可被ERK1/2信号通道阻断剂PD98059阻断。HRP不能阻断(P)RR激活所致的ERK1/2磷酸化,不能使TGF-β表达降低。结论:在体外培养的HRMCs中,prorenin能够激活(P)RR,使ERK1/2信号通道活化导致TGF-β水平增高。而HRP不能阻断(P)RR激活后ERK1/2的磷酸化及TGF-β表达的增多。展开更多
A discrete event heuristic feedback control system fo r a steel plate storage at Odense Steel Shipyard Ltd is developed and implemente d in a computer-based simulation model. The plant is subject to stochastic dist ur...A discrete event heuristic feedback control system fo r a steel plate storage at Odense Steel Shipyard Ltd is developed and implemente d in a computer-based simulation model. The plant is subject to stochastic dist urbances. The control system is able to handle this stochastic behaviour bec ause of the feedback design. The present simulation results indicate that a bene fit in the range of 30%～40% is reachable by modifying the plant. Plant description The steel plate storage is located at Odense Steel Shipyard Ltd, Denmark. The st eel plate storage contains steel plates used to build ship sections. The size of the storage is 600x35 meters. It consists of 32x8 stacks of plates. Plates are delivered and removed dynamically. The plate storage contains 5.000 steel plates in average. Over time, new plates delivered to the storage replace plates removed from the storage. The maximum si ze of a plate is 17x4 meters with a weight of up to 22 tons. The plates are uniq ue and dedicated to a specific purpose but in average the 5 000 plates consist o f 2 500 types. Plates are transported around the plate storage by two portal cranes. The cranes drive on a common rail and hence they cannot overtake each other. The cranes us e magnetic force to lift the plates. The crane can deliver the lifted plate to a conveyor belt or to another stack depending on whether the plate has been order ed for the current day or later. The plant is subject to different kinds of disturbances. The processes performed at the plant are stochastic. Furthermore, the due dates of the plates are frequ ently changed and hence the effect of previously sorting might be lost. The control task is to dispatch movements of plates to the two cranes. The overa ll goal is to minimize the costs at the plate storage and hence the two cranes a re used for executing the movements as fast as possible without colliding and re spect other physical constraints. Problem solution Different approaches have been investigated to solve the problem. A discrete eve nt heuristic feedback controller is used as an online algorithm. The controller is combined with a local search heuristic for improving the initial plan deliver ed by the controller. The improved plan is used as a reference for another feedb ack controller. To indicate the size of the problem, consider an example where the online algori thm is used for executing 600 movements for one day. Through the day the algorit hm finds the locally optimal movement between 20 executable movements. Then the number of different solutions is 20 600! Notice that the possibility of cho osing another destination for the plates to be moved is not taken into account! Results Without time disturbances the controller using an optimised plan as a reference supply the best performance. Nevertheless, when time disturbances are introduces the discrete event heuristic feedback controller performs as well. The comparis on depends on the size of the disturbances. When the disturbances reach a certai n level the discrete event heuristic feedback controller supply the best perform ance and robustness. If the performance is compared with the working system of today, it seems realis tic that a 30%～40% reduction in time is reachable.展开更多
In this article, a new model of establishing flexible and utility bi-bliographic systems dependent on microcomputer or minicomputer is di-scussed and compared with the models of large systems and PC-basedsystems. A pr...In this article, a new model of establishing flexible and utility bi-bliographic systems dependent on microcomputer or minicomputer is di-scussed and compared with the models of large systems and PC-basedsystems. A practical example based on this model, Union Catalog Systemof Serials in Western Languages, is used to show our solution for thedevelopment and utilization of the systems of this kind.展开更多
Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes.The main objective of this work is to develop active control mechanism based on...Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes.The main objective of this work is to develop active control mechanism based on fuzzy logic controller(FLC) and linear quadratic regulator(LQR) for improving vehicle path following,roll and handling performances simultaneously.3-DOF vehicle model including yaw rate,lateral velocity(lateral dynamic) and roll angle(roll dynamic) were developed.The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal.The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers.Simulation results demonstrate that in both cases(FLC and LQR controllers) by reducing roll angle,lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver,which ensures vehicle stability and handling properties.Finally,the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.展开更多
A control algorithm for improving vehicle handling was proposed by applying right angle to the steering wheel,based on the nonlinear adaptive optimal control(NAOC).A nonlinear 4-DOF model was initially developed,then ...A control algorithm for improving vehicle handling was proposed by applying right angle to the steering wheel,based on the nonlinear adaptive optimal control(NAOC).A nonlinear 4-DOF model was initially developed,then it was simplified to a 2-DOF model with reasonable assumptions to design observer and optimal controllers.Then a simplified model was developed for steering system.The numerical simulations were carried out using vehicle parameters for standard maneuvers in dry and wet road conditions.Moreover,the hardware in the loop method was implemented to prove the controller ability in realistic conditions.Simulation results obviously show the effectiveness of NAOC on vehicle handling and reveal that the proposed controller can significantly improve vehicle handling during severe maneuvers.展开更多
New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the s...New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the stress is released with the mining process. And applying the catastrophe theory, the influencing factors of induction caving roof are studied in the emptied areas, such as the mechanical property of the surrounding rock, the area of the gob,the scope and dimension of tensile stress. The results show that the key factor is the area of the gob to the method of the induction caving roof. Then according to the geology and the ore characteristic, the three dimension FEM mechanical model is built in Tongkeng Mine, the laws of the tensile stress are analyzed to the space and the time in the roof with the mining, then it is rational design to the mine step and time of the handing the roof.展开更多
An improved genetic algorithm（IGA） based on a novel selection strategy to handle nonlinear programming problems is proposed.Each individual in selection process is represented as a three-dimensional feature vector w...An improved genetic algorithm（IGA） based on a novel selection strategy to handle nonlinear programming problems is proposed.Each individual in selection process is represented as a three-dimensional feature vector which is composed of objective function value,the degree of constraints violations and the number of constraints violations.It is easy to distinguish excellent individuals from general individuals by using an individuals＇ feature vector.Additionally,a local search（LS） process is incorporated into selection operation so as to find feasible solutions located in the neighboring areas of some infeasible solutions.The combination of IGA and LS should offer the advantage of both the quality of solutions and diversity of solutions.Experimental results over a set of benchmark problems demonstrate that IGA has better performance than other algorithms.展开更多
With applying the information technology to the military field, the advantages and importance of the networked combat are more and more obvious. In order to make full use of limited battlefield resources and maximally...With applying the information technology to the military field, the advantages and importance of the networked combat are more and more obvious. In order to make full use of limited battlefield resources and maximally destroy enemy targets from arbitrary angle in a limited time, the research on firepower nodes dynamic deployment becomes a key problem of command and control. Considering a variety of tactical indexes and actual constraints in air defense, a mathematical model is formulated to minimize the enemy target penetration probability. Based on characteristics of the mathematical model and demands of the deployment problems, an assistance-based algorithm is put forward which combines the artificial potential field （APF） method with a memetic algorithm. The APF method is employed to solve the constraint handling problem and generate feasible solutions. The constrained optimization problem transforms into an optimization problem of APF parameters adjustment, and the dimension of the problem is reduced greatly. The dynamic deployment is accomplished by generation and refinement of feasible solutions. The simulation results show that the proposed algorithm is effective and feasible in dynamic situation.展开更多
Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department t...Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department to have sufficient time to formulate corresponding traffic flow control measures.In hence,it is meaningful to establish an accurate short-term traffic flow method and provide reference for peak traffic flow warning.This paper proposed a new hybrid model for traffic flow forecasting,which is composed of the variational mode decomposition(VMD)method,the group method of data handling(GMDH)neural network,bi-directional long and short term memory(BILSTM)network and ELMAN network,and is optimized by the imperialist competitive algorithm(ICA)method.To illustrate the performance of the proposed model,there are several comparative experiments between the proposed model and other models.The experiment results show that 1)BILSTM network,GMDH network and ELMAN network have better predictive performance than other single models;2)VMD can significantly improve the predictive performance of the ICA-GMDH-BILSTM-ELMAN model.The effect of VMD method is better than that of EEMD method and FEEMD method.To conclude,the proposed model which is made up of the VMD method,the ICA method,the BILSTM network,the GMDH network and the ELMAN network has excellent predictive ability for traffic flow series.展开更多
Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability...Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.展开更多
Flotation column is widely used as the separation equipment for fine mineral due to its high selectivity. However, this device may be unsuitable for the coarse particle flotation and has high handling ability. A two-s...Flotation column is widely used as the separation equipment for fine mineral due to its high selectivity. However, this device may be unsuitable for the coarse particle flotation and has high handling ability. A two-stage flotation column with dimensions of 2 000 mm×1 000 mm×4 000 mm was designed to enhance the column flotation process. The energy input was modified by adjusting the flow rate and the head of circulating pump. The flotation column was designed with low energy input in the first stage(speed flotation stage) to recover easy-to-float materials quickly, and high energy input in the second stage(recovery stage) to recover difficult-to-float minerals compulsorily. Contrast experiments on the throughput and coarse coal recovery of high ash coal from the Kailuan Mine were conducted using conventional single-stage flotation column and the two-stage flotation column. The results show that the combustible matter recovery of the two-stage flotation column is 5.25% higher than that of the conventional single-stage flotation column. However, the ash contents of clean coal for both columns are similar. Less coarse coals with low ash are obtained using the two-stage flotation column than that using the single-stage column flotation with the same handling ability. The two-stage flotation column process can enhance coal flotation compared with the conventional single-stage column flotation.展开更多
DM usually means an efficient knowledge discovery from database, and the immune algorithm is a biological theory-based and global searching algorithm. A novel induction algorithm is proposed here which integrates a po...DM usually means an efficient knowledge discovery from database, and the immune algorithm is a biological theory-based and global searching algorithm. A novel induction algorithm is proposed here which integrates a power of individual immunity and an evolutionary mechanism of population. This algorithm does not take great care of discovering some classifying information, but unknown knowledge or a predication on higher level rules. Theoretical analysis and simulations both show that this algorithm is prone to the stabilization of a population and the improvement of entire capability, and also keeping a high degree of preciseness during the rule induction.展开更多
Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimizati...Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimization methods capable of providing the best trade-off designs compromising both criteria simultaneously. Although many studies have been performed on multi-objective optimization of vehicle suspension system, only a few of them have used probabilistic approaches considering effects of uncertainties in the design. However, it has been proved that optimum point obtained from deterministic optimization without taking into account the effects of uncertainties may lead to high-risk points instead of optimum ones. In this work, reliability-based robust multi-objective optimization of a 5 degree of freedom （5-DOF） vehicle suspension system is performed using method of non-dominated sorting genetic algorithm-II （NSGA-II） in conjunction with Monte Carlo simulation （MCS） to obtain best designs considering both comfort and handling. Road profile is modeled as a random function using power spectral density （PSD） which is in better accordance with reality. To accommodate the robust approach, the variance of all objective functions is also considered to be minimized. Also, to take into account the reliability criterion, a reliability-based constraint is considered in the optimization. A deterministic optimization has also been performed to compare the results with probabilistic study and some other deterministic studies in the literature. In addition, sensitivity analysis has been performed to reveal the effects of different design variables on objective functions. To introduce the best trade-off points from the obtained Pareto fronts, TOPSIS method has been employed. Results show that optimum design point obtained from probabilistic optimization in this work provides better performance while demonstrating very good reliability and robustness. However, other optimum points from deterministic optimizations violate the regarded constraints in the presence of uncertainties.展开更多
基金National Natural Science Foundation of China(32301718)Chinese Academy of Agricultural Sciences under the Special Institute-level Coordination Project for Basic Research Operating Costs(S202328)。
文摘The cold chain in the production area of fruits and vegetables is the primary link to reduce product loss and improve product quality,but it is also a weak link.With the application of big data technology in cold chain logistics,intelligent devices,and technologies have become important carriers for improving the efficiency of cold chain logistics in fruit and vegetable production areas,extending the shelf life of fruits and vegetables,and reducing fruit and vegetable losses.They have many advantages in fruit and vegetable pre-cooling,sorting and packaging,testing,warehousing,transportation,and other aspects.This article summarizes the rapidly developing and widely used intelligent technologies at home and abroad in recent years,including automated guided vehicle intelligent handling based on electromagnetic or optical technology,intelligent sorting based on sensors,electronic optics,and other technologies,intelligent detection based on computer vision technology,intelligent transportation based on perspective imaging technology,etc.It analyses and studies the innovative research and achievements of various scholars in applying intelligent technology in fruit and vegetable cold chain storage,sorting,detection,transportation,and other links,and improves the efficiency of fruit and vegetable cold chain logistics.However,applying intelligent technology in fruit and vegetable cold chain logistics also faces many problems.The challenges of high cost,difficulty in technological integration,and talent shortages have limited the development of intelligent technology in the field of fruit and vegetable cold chains.To solve the current problems,it is proposed that costs be controlled through independent research and development,technological innovation,and other means to lower the entry threshold for small enterprises.Strengthen integrating intelligent technology and cold chain logistics systems to improve data security and system compatibility.At the same time,the government should introduce relevant policies,provide necessary financial support,and establish talent training mechanisms.Accelerate the development and improvement of intelligent technology standards in the field of cold chain logistics.Through technological innovation,cost control,talent cultivation,and policy guidance,we aim to promote the upgrading of the agricultural industry and provide ideas for improving the quality and efficiency of fruit and vegetable cold chain logistics.
文摘目的:观察肾素前体(prorenin)能否激活体外培养的人肾系膜细胞(HRMCs)膜表面的肾素(前体)受体[(P)RR],从而活化细胞外信号调节激酶1/2(ERK1/2)信号通路。方法:体外培养HRMCs。以血管紧张素Ⅱ1型受体(AT1)阻断剂olmsartan和血管紧张素Ⅱ2型受体(AT2)阻断剂PD123319孵育细胞,再以prorenin刺激细胞,并用ERK1/2抑制剂PD98059和HRP(handle region peptide)干预。用免疫蛋白印迹方法(Western blotting)和酶标记免疫吸附测定方法(ELISA)测定目的蛋白水平,以逆转录聚合酶链反应(RT-PCR)方法测定mRNA水平。结果:Prorenin作用于体外培养的HRMCs后,在阻断AT1和AT2受体时,能激活(P)RR使ERK1/2磷酸化增强、转化生长因子(TGF-β)水平增高。这种ERK1/2信号通路的激活是(P)RR激活后效应,并可被ERK1/2信号通道阻断剂PD98059阻断。HRP不能阻断(P)RR激活所致的ERK1/2磷酸化,不能使TGF-β表达降低。结论:在体外培养的HRMCs中,prorenin能够激活(P)RR,使ERK1/2信号通道活化导致TGF-β水平增高。而HRP不能阻断(P)RR激活后ERK1/2的磷酸化及TGF-β表达的增多。
文摘A discrete event heuristic feedback control system fo r a steel plate storage at Odense Steel Shipyard Ltd is developed and implemente d in a computer-based simulation model. The plant is subject to stochastic dist urbances. The control system is able to handle this stochastic behaviour bec ause of the feedback design. The present simulation results indicate that a bene fit in the range of 30%～40% is reachable by modifying the plant. Plant description The steel plate storage is located at Odense Steel Shipyard Ltd, Denmark. The st eel plate storage contains steel plates used to build ship sections. The size of the storage is 600x35 meters. It consists of 32x8 stacks of plates. Plates are delivered and removed dynamically. The plate storage contains 5.000 steel plates in average. Over time, new plates delivered to the storage replace plates removed from the storage. The maximum si ze of a plate is 17x4 meters with a weight of up to 22 tons. The plates are uniq ue and dedicated to a specific purpose but in average the 5 000 plates consist o f 2 500 types. Plates are transported around the plate storage by two portal cranes. The cranes drive on a common rail and hence they cannot overtake each other. The cranes us e magnetic force to lift the plates. The crane can deliver the lifted plate to a conveyor belt or to another stack depending on whether the plate has been order ed for the current day or later. The plant is subject to different kinds of disturbances. The processes performed at the plant are stochastic. Furthermore, the due dates of the plates are frequ ently changed and hence the effect of previously sorting might be lost. The control task is to dispatch movements of plates to the two cranes. The overa ll goal is to minimize the costs at the plate storage and hence the two cranes a re used for executing the movements as fast as possible without colliding and re spect other physical constraints. Problem solution Different approaches have been investigated to solve the problem. A discrete eve nt heuristic feedback controller is used as an online algorithm. The controller is combined with a local search heuristic for improving the initial plan deliver ed by the controller. The improved plan is used as a reference for another feedb ack controller. To indicate the size of the problem, consider an example where the online algori thm is used for executing 600 movements for one day. Through the day the algorit hm finds the locally optimal movement between 20 executable movements. Then the number of different solutions is 20 600! Notice that the possibility of cho osing another destination for the plates to be moved is not taken into account! Results Without time disturbances the controller using an optimised plan as a reference supply the best performance. Nevertheless, when time disturbances are introduces the discrete event heuristic feedback controller performs as well. The comparis on depends on the size of the disturbances. When the disturbances reach a certai n level the discrete event heuristic feedback controller supply the best perform ance and robustness. If the performance is compared with the working system of today, it seems realis tic that a 30%～40% reduction in time is reachable.
文摘In this article, a new model of establishing flexible and utility bi-bliographic systems dependent on microcomputer or minicomputer is di-scussed and compared with the models of large systems and PC-basedsystems. A practical example based on this model, Union Catalog Systemof Serials in Western Languages, is used to show our solution for thedevelopment and utilization of the systems of this kind.
文摘Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes.The main objective of this work is to develop active control mechanism based on fuzzy logic controller(FLC) and linear quadratic regulator(LQR) for improving vehicle path following,roll and handling performances simultaneously.3-DOF vehicle model including yaw rate,lateral velocity(lateral dynamic) and roll angle(roll dynamic) were developed.The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal.The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers.Simulation results demonstrate that in both cases(FLC and LQR controllers) by reducing roll angle,lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver,which ensures vehicle stability and handling properties.Finally,the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.
文摘A control algorithm for improving vehicle handling was proposed by applying right angle to the steering wheel,based on the nonlinear adaptive optimal control(NAOC).A nonlinear 4-DOF model was initially developed,then it was simplified to a 2-DOF model with reasonable assumptions to design observer and optimal controllers.Then a simplified model was developed for steering system.The numerical simulations were carried out using vehicle parameters for standard maneuvers in dry and wet road conditions.Moreover,the hardware in the loop method was implemented to prove the controller ability in realistic conditions.Simulation results obviously show the effectiveness of NAOC on vehicle handling and reveal that the proposed controller can significantly improve vehicle handling during severe maneuvers.
基金Project(50490274) supported by the National Nature Science Foundation of China
文摘New method for handling roof of the base successive mining is proposed, which is induction caving in the roof. The key is that it is made certain to the station of the space-time in the induction caving roof, as the stress is released with the mining process. And applying the catastrophe theory, the influencing factors of induction caving roof are studied in the emptied areas, such as the mechanical property of the surrounding rock, the area of the gob,the scope and dimension of tensile stress. The results show that the key factor is the area of the gob to the method of the induction caving roof. Then according to the geology and the ore characteristic, the three dimension FEM mechanical model is built in Tongkeng Mine, the laws of the tensile stress are analyzed to the space and the time in the roof with the mining, then it is rational design to the mine step and time of the handing the roof.
基金supported by the National Natural Science Foundation of China (60632050)National Basic Research Program of Jiangsu Province University (08KJB520003)
文摘An improved genetic algorithm（IGA） based on a novel selection strategy to handle nonlinear programming problems is proposed.Each individual in selection process is represented as a three-dimensional feature vector which is composed of objective function value,the degree of constraints violations and the number of constraints violations.It is easy to distinguish excellent individuals from general individuals by using an individuals＇ feature vector.Additionally,a local search（LS） process is incorporated into selection operation so as to find feasible solutions located in the neighboring areas of some infeasible solutions.The combination of IGA and LS should offer the advantage of both the quality of solutions and diversity of solutions.Experimental results over a set of benchmark problems demonstrate that IGA has better performance than other algorithms.
基金supported by the National Outstanding Youth Science Foundation (60925011)the National Natural Science Foundation of China (61203181)
文摘With applying the information technology to the military field, the advantages and importance of the networked combat are more and more obvious. In order to make full use of limited battlefield resources and maximally destroy enemy targets from arbitrary angle in a limited time, the research on firepower nodes dynamic deployment becomes a key problem of command and control. Considering a variety of tactical indexes and actual constraints in air defense, a mathematical model is formulated to minimize the enemy target penetration probability. Based on characteristics of the mathematical model and demands of the deployment problems, an assistance-based algorithm is put forward which combines the artificial potential field （APF） method with a memetic algorithm. The APF method is employed to solve the constraint handling problem and generate feasible solutions. The constrained optimization problem transforms into an optimization problem of APF parameters adjustment, and the dimension of the problem is reduced greatly. The dynamic deployment is accomplished by generation and refinement of feasible solutions. The simulation results show that the proposed algorithm is effective and feasible in dynamic situation.
基金Project(61873283)supported by the National Natural Science Foundation of ChinaProject(KQ1707017)supported by the Changsha Science&Technology Project,ChinaProject(2019CX005)supported by the Innovation Driven Project of the Central South University,China。
文摘Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department to have sufficient time to formulate corresponding traffic flow control measures.In hence,it is meaningful to establish an accurate short-term traffic flow method and provide reference for peak traffic flow warning.This paper proposed a new hybrid model for traffic flow forecasting,which is composed of the variational mode decomposition(VMD)method,the group method of data handling(GMDH)neural network,bi-directional long and short term memory(BILSTM)network and ELMAN network,and is optimized by the imperialist competitive algorithm(ICA)method.To illustrate the performance of the proposed model,there are several comparative experiments between the proposed model and other models.The experiment results show that 1)BILSTM network,GMDH network and ELMAN network have better predictive performance than other single models;2)VMD can significantly improve the predictive performance of the ICA-GMDH-BILSTM-ELMAN model.The effect of VMD method is better than that of EEMD method and FEEMD method.To conclude,the proposed model which is made up of the VMD method,the ICA method,the BILSTM network,the GMDH network and the ELMAN network has excellent predictive ability for traffic flow series.
文摘Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.
基金Project(2012CB214905)supported by the National Basic Research Program of ChinaProject(51074157)supported by the National Natural Science Foundation of China
文摘Flotation column is widely used as the separation equipment for fine mineral due to its high selectivity. However, this device may be unsuitable for the coarse particle flotation and has high handling ability. A two-stage flotation column with dimensions of 2 000 mm×1 000 mm×4 000 mm was designed to enhance the column flotation process. The energy input was modified by adjusting the flow rate and the head of circulating pump. The flotation column was designed with low energy input in the first stage(speed flotation stage) to recover easy-to-float materials quickly, and high energy input in the second stage(recovery stage) to recover difficult-to-float minerals compulsorily. Contrast experiments on the throughput and coarse coal recovery of high ash coal from the Kailuan Mine were conducted using conventional single-stage flotation column and the two-stage flotation column. The results show that the combustible matter recovery of the two-stage flotation column is 5.25% higher than that of the conventional single-stage flotation column. However, the ash contents of clean coal for both columns are similar. Less coarse coals with low ash are obtained using the two-stage flotation column than that using the single-stage column flotation with the same handling ability. The two-stage flotation column process can enhance coal flotation compared with the conventional single-stage column flotation.
基金This project was supported by the National Natural Science Foundation of China (No. 60073053) the Nationa1 "863" High-Tech P
文摘DM usually means an efficient knowledge discovery from database, and the immune algorithm is a biological theory-based and global searching algorithm. A novel induction algorithm is proposed here which integrates a power of individual immunity and an evolutionary mechanism of population. This algorithm does not take great care of discovering some classifying information, but unknown knowledge or a predication on higher level rules. Theoretical analysis and simulations both show that this algorithm is prone to the stabilization of a population and the improvement of entire capability, and also keeping a high degree of preciseness during the rule induction.
文摘Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimization methods capable of providing the best trade-off designs compromising both criteria simultaneously. Although many studies have been performed on multi-objective optimization of vehicle suspension system, only a few of them have used probabilistic approaches considering effects of uncertainties in the design. However, it has been proved that optimum point obtained from deterministic optimization without taking into account the effects of uncertainties may lead to high-risk points instead of optimum ones. In this work, reliability-based robust multi-objective optimization of a 5 degree of freedom （5-DOF） vehicle suspension system is performed using method of non-dominated sorting genetic algorithm-II （NSGA-II） in conjunction with Monte Carlo simulation （MCS） to obtain best designs considering both comfort and handling. Road profile is modeled as a random function using power spectral density （PSD） which is in better accordance with reality. To accommodate the robust approach, the variance of all objective functions is also considered to be minimized. Also, to take into account the reliability criterion, a reliability-based constraint is considered in the optimization. A deterministic optimization has also been performed to compare the results with probabilistic study and some other deterministic studies in the literature. In addition, sensitivity analysis has been performed to reveal the effects of different design variables on objective functions. To introduce the best trade-off points from the obtained Pareto fronts, TOPSIS method has been employed. Results show that optimum design point obtained from probabilistic optimization in this work provides better performance while demonstrating very good reliability and robustness. However, other optimum points from deterministic optimizations violate the regarded constraints in the presence of uncertainties.
