To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In ...To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In this scheme, if w = (w1, w2) is the message to be sent in block b, the relay will decode message w1 and generate a new message z at the end of block b, and the receiver will decode message w1 at the end of block b + 1 and decode message z and w2 at the end of block b + 2. Analysis results show that this new communication scheme can achieve the same Chong-Motani-Garg bounds and the decoding delay is only two blocks which is much shorter than that of backward decoding. Therefore, Chong-Motani-Garg bounds can be achieved by a forward decoding-based communication scheme with short decoding delay.展开更多
Orthomorphism on F2^n is a kind of elementary pemmtation with good cryptographic properties. This paper proposes a hybrid strategy of Particle Swarm Optimization (PSO) and Sirrmlated Annealing (SA) for finding ort...Orthomorphism on F2^n is a kind of elementary pemmtation with good cryptographic properties. This paper proposes a hybrid strategy of Particle Swarm Optimization (PSO) and Sirrmlated Annealing (SA) for finding orthomorphisrm with good cryptographic properties. By experiment based on this strategy, we get some orthorrorphisrm on F2^n = 5, 6, 7, 9, 10) with good cryptographic properties in the open document for the first time, and the optirml orthorrrphism on F found in this paper also does better than the one proposed by Feng Dengguo et al. in stream cipher Loiss in difference uniformity, algebraic degree, algebraic irrarnity and corresponding pernmtation polynomial degree. The PSOSA hybrid strategy for optimizing orthomerphism in this paper makes design of orthorrorphisrm with good cryptographic properties automated, efficient and convenient, which proposes a new approach to design orthornorphisrm.展开更多
Applying ontology to describe resource metadata richly in the peer-to-peer environment has become current research trend. In this semantic peer-to-peer environment, indexing semantic element of resource description to...Applying ontology to describe resource metadata richly in the peer-to-peer environment has become current research trend. In this semantic peer-to-peer environment, indexing semantic element of resource description to support efficient resource location is a difficult and challenging problem. This paper provided a hybrid indexing architecture, which combines local indexing and global indexing. It uses community strategy and semantic routing strategy to organize key layer metadata element and uses DHT (distributed hash table) to index extensional layer metadata element. Compared with related system, this approach is more efficient in resource location and more scalable.展开更多
For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude...For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude oil blending process. The objective is to keep the property of feedstock, mainly described by the true boiling point (TBP) data, consistent and suitable. Firstly, the mathematical model is established. Then, a heuristically initialized hybrid iterative (HIHI) algorithm based on a two-level optimization structure, in which tabu search (TS) and differential evolution (DE) are used for upper-level and lower-level optimization, respectively, is proposed to get the model solution. Finally, the effectiveness and efficiency of the scheduling strategy is validated via real data from a certain refinery.展开更多
According to the complex nonlinear relationship between gas emission and its effect factors, and the shortcomings that basic colony algorithm is slow, prone to early maturity and stagnation during the search, we intro...According to the complex nonlinear relationship between gas emission and its effect factors, and the shortcomings that basic colony algorithm is slow, prone to early maturity and stagnation during the search, we introduced a hybrid optimization strategy into a max-rain ant colony algorithm, then use this improved ant colony algorithm to estimate the scope of RBF network parameters. According to the amount of pheromone of discrete points, the authors obtained from the interval of net- work parameters, ants optimize network parameters. Finally, local spatial expansion is introduced to get further optimization of the network. Therefore, we obtain a better time efficiency and solution efficiency optimization model called hybrid improved max-min ant system (H1-MMAS). Simulation experiments, using these theory to predict the gas emission from the working face, show that the proposed method have high prediction feasibility and it is an effective method to predict gas emission.展开更多
Based on the log-linear virtual age process, an imperfect preventive maintenance policy for numerical control(NC)machine tools with random maintenance quality is proposed. The proposed model is a combination of the Ki...Based on the log-linear virtual age process, an imperfect preventive maintenance policy for numerical control(NC)machine tools with random maintenance quality is proposed. The proposed model is a combination of the Kijima type virtual age model and the failure intensity adjustment model. Maintenance intervals of the proposed hybrid model are derived when the failure intensity increase factor and the restoration factor are both random variables with uniform distribution. The optimal maintenance policy in infinite time horizon is presented. A numerical example is given when the failures of NC machine tools are described by the log-linear process. Finally, a discussion is presented to show how the optimal results depend on the different cost parameters.展开更多
In this paper, a hybrid automatic optimization strategy is proposed for the design of underwater robot lines. Isight is introduced as an integration platform. The construction of this platform is based on the user pro...In this paper, a hybrid automatic optimization strategy is proposed for the design of underwater robot lines. Isight is introduced as an integration platform. The construction of this platform is based on the user programming and several commercial software including UG6.0, GAMBIT2.4.6 and FLUENT12.0. An intelligent parameter optimization method, the particle swarm optimization, is incorporated into the platform. To verify the strategy proposed, a simulation is conducted on the underwater robot model 5470, which originates from the DTRC SUBOFF project. With the automatic optimization platform, the minimal resistance is taken as the optimization goal;the wet surface area as the constraint condition; the length of the fore-body, maximum body radius and after-body's minimum radius as the design variables. With the CFD calculation, the RANS equations and the standard turbulence model are used for direct numerical simulation. By analyses of the simulation results, it is concluded that the platform is of high efficiency and feasibility. Through the platform, a variety of schemes for the design of the lines are generated and the optimal solution is achieved. The combination of the intelligent optimization algorithm and the numerical simulation ensures a global optimal solution and improves the efficiency of the searching solutions.展开更多
Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy...Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.展开更多
This paper investigates on the base stations(BSs) sleeping control and energy saving in wireless network. The objective is to find the sleeping control and energy saving configuration between total power consumption a...This paper investigates on the base stations(BSs) sleeping control and energy saving in wireless network. The objective is to find the sleeping control and energy saving configuration between total power consumption and average video's quality. On the Software Defined Network(SDN) access network architecture, a type of sleeping control and active BSs' optimal transmitting time strategy is considered, the BS sleeps when there is no active users, and wakes up after a period of vacation time. In this paper, we study the active users grouping strategy, In order to spare more BSs into sleeping mode. Then this paper proposes an active BS transmitting time optimal strategy according to the users' Qo S. In the proposed strategy, the active BSs' transmitting time is minimized in order to save energy. This paper employs the mixed integer-programming model to present this optimization problem. Then we utilized a novel algorithm to save the energy in access networks and also meet the Qo S requirements. Both the analytical and simulation results show that the algorithm can effectively save energy in the access network BSs.展开更多
To improve efficiency of search engines, the query result cache has drawn much attention re- cently. According to the query processing and user's query logs locality, a new hybrid result cache strategy which associat...To improve efficiency of search engines, the query result cache has drawn much attention re- cently. According to the query processing and user's query logs locality, a new hybrid result cache strategy which associates with caching heat and worth is proposed to compute cache score in accord- ance with cost-aware strategies. Exactly, query repeated distance and query length factor are utilized to improve the static result policy, and the dynamic policy is adjusted by the caching worth. The hy- brid result cache is implemented in term of the document content and document ids (docIds) se- quence. Based on a score format and the new hybrid structure, an initial algorithm and a new rou- ting algorithm are designed for result cache. Experiments' results show that the improved caching policies decrease the average response time effectively, and increase the system throughput signifi- cantly. By choosing comfortable combination of page cache and docIds cache, the new hybrid cac- hing strategy almost reduces more than 20% of the only cache and docId-only cache. average query time compared with the basic page-展开更多
A two-step information extraction method is presented to capture the specific index-related information more accurately.In the first step,the overall process variables are separated into two sets based on Pearson corr...A two-step information extraction method is presented to capture the specific index-related information more accurately.In the first step,the overall process variables are separated into two sets based on Pearson correlation coefficient.One is process variables strongly related to the specific index and the other is process variables weakly related to the specific index.Through performing principal component analysis(PCA)on the two sets,the directions of latent variables have changed.In other words,the correlation between latent variables in the set with strong correlation and the specific index may become weaker.Meanwhile,the correlation between latent variables in the set with weak correlation and the specific index may be enhanced.In the second step,the two sets are further divided into a subset strongly related to the specific index and a subset weakly related to the specific index from the perspective of latent variables using Pearson correlation coefficient,respectively.Two subsets strongly related to the specific index form a new subspace related to the specific index.Then,a hybrid monitoring strategy based on predicted specific index using partial least squares(PLS)and T2statistics-based method is proposed for specific index-related process monitoring using comprehensive information.Predicted specific index reflects real-time information for the specific index.T2statistics are used to monitor specific index-related information.Finally,the proposed method is applied to Tennessee Eastman(TE).The results indicate the effectiveness of the proposed method.展开更多
A genetic-fuzzy HEV control strategy based on driving cycle recognition (DCR) was built. Six driving cycles were selected to represent different traffic conditions e.g. freeway, urban, suburb. A neural algorithm was...A genetic-fuzzy HEV control strategy based on driving cycle recognition (DCR) was built. Six driving cycles were selected to represent different traffic conditions e.g. freeway, urban, suburb. A neural algorithm was used for traffic condition recognition based on ten parameters of each driving cycle. The DCR was utilized for optimization of the HEV control parameters using a genetic-fuzzy approach. A fuzzy logic controller (FLC) was designed to be intelligent to manage the engine to work in the vicinity of its optimal condition. The fuzzy membership function parameters were optimized using the genetic algorithm (GA) for each driving cycle. The result is that the DCR_ fuzzy controller can reduce the fuel consumption by 1. 9%, higher than only CYC _ HWFET optimized fuzzy (0.2%) or CYC _ WVUSUB optimized fuzzy (0.7%). The DCR_ fuzzy method can get the better result than only optimizing one cycle on the complex real traffic conditions.展开更多
The shift scheduling system of the transmission has an important effect on the dynamic and economic performance of hybrid vehicles. In this work, shift scheduling strategies are developed for parallel hybrid construct...The shift scheduling system of the transmission has an important effect on the dynamic and economic performance of hybrid vehicles. In this work, shift scheduling strategies are developed for parallel hybrid construction vehicles. The effect of power distribution and direction on shift characteristics of the parallel hybrid vehicle with operating loads is evaluated, which must be considered for optimal shift control. A power distribution factor is defined to accurately describe the power distribution and direction in various parallel hybrid systems. This paper proposes a Levenberg-Marquardt algorithm optimized neural network shift scheduling strategy. The methodology contains two objective functions, it is a dynamic combination of a dynamic shift schedule for optimal vehicle acceleration, and an energy-efficient shift schedule for optimal powertrain efficiency. The study is performed on a test bench under typical operating conditions of a wheel loader. The experimental results show that the proposed strategies offer effective and competitive shift performance.展开更多
EVs (electric vehicles) have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the ...EVs (electric vehicles) have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the high adoption of EVs will impose a burden on the power system, especially for neighborhood level network. In this paper, we propose a mixed control framework for EV charging scheduling to mitigate its impact on the power network. A metric for modeling customer's satisfaction is also proposed to compare the user satisfaction for different algorithms. The impacts of the proposed algorithms on EV charging cost, EV penetration and peak power reduction are evaluated with real data for a neighborhood level network. The simulation results demonstrate the effectiveness of the proposed algorithms.展开更多
Multivessel batch distillation(MVBD) is mainly used to separate mixtures with more than two components. In this article, a new operation mode with MVBD is proposed for separation of binary mixtures under total reflux....Multivessel batch distillation(MVBD) is mainly used to separate mixtures with more than two components. In this article, a new operation mode with MVBD is proposed for separation of binary mixtures under total reflux. A mathematic model is setup for the simulation. The proposed operation policy and the regular operation with constant reflux are compared theoretically and experimentally. The results show that the new operation mode has great advantages in time saving and operation flexibility. MVBD presents great potential for separation with high efficiency.展开更多
Aimed at the relatively lower energy density and complicated coordinating operation between two power sources,a special energy control strategy is required to maximize the fuel saving potential.Then a new type of conf...Aimed at the relatively lower energy density and complicated coordinating operation between two power sources,a special energy control strategy is required to maximize the fuel saving potential.Then a new type of configuration for hydrostatic transmission hybrid vehicles(PHHV) and the selection criterion for important components are proposed.Based on the optimization of planet gear transmission ratio and the analysis of optimal energy distribution for the proposed PHHV on a representative urban driving cycle,a fuzzy torque control strategy and a braking energy regeneration strategy are designed and developed to realize the real-time control of energy for the proposed PHHV.Simulation results demonstrate that the energy control strategy effectively improves the fuel economy of PHHV.展开更多
A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was establi...A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.展开更多
This paper mainly analyzes a hybrid position/force control strategy and experiment of a six-cable driven parallel manipulator for a forty-meter aperture radio telescope. Through the establishments of a kinematic model...This paper mainly analyzes a hybrid position/force control strategy and experiment of a six-cable driven parallel manipulator for a forty-meter aperture radio telescope. Through the establishments of a kinematic model, a catenary model and a cable-force characteristics model, a basic method is presented based on preventing the pseudo-drag problem of a flexible cable and realizing the hybrid position/force control for a six-cable driven parallel manipulator, and a hybrid position/force control system is developed. Some specific experiments in two typical velocities for astronomical observations are carried out. Experimental results show that the tracking accuracy is related to the speed of the movement. The desired tracking accuracy of the support system is achieved through an effective hybrid position/force control strategy, the cable forces are controlled effectively, and the pseudo-drag problem of flexible cable is solved. This study establishes the foundation of achieving the harmonious movement of the six-cable driven parallel manipulator, A-B rotating platform and the Stewart fine tuninz olatform.展开更多
After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy ...After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy recovery system is discussed,which is validated and evaluated by simulation.The simulation results show that the proposed control strategy can achieve balance of the power and keep the state of charge(SOC) of ultra capacitor in a reasonable range,and the fuel consumption can be reduced by about 20.8% compared with the conventional diesel forklift.Finally,the feasibility of the simulation results is experimentally verified based on the lifting energy recovery system.展开更多
基金The Free Research Fund of National Mobile Communi-cations Research Laboratory of Southeast University(No.2008B06)the Na-tional Basic Research Program of China (973 Program)(No.2007CB310603)
文摘To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In this scheme, if w = (w1, w2) is the message to be sent in block b, the relay will decode message w1 and generate a new message z at the end of block b, and the receiver will decode message w1 at the end of block b + 1 and decode message z and w2 at the end of block b + 2. Analysis results show that this new communication scheme can achieve the same Chong-Motani-Garg bounds and the decoding delay is only two blocks which is much shorter than that of backward decoding. Therefore, Chong-Motani-Garg bounds can be achieved by a forward decoding-based communication scheme with short decoding delay.
基金supported by the National Natural Science Foundation of China under Grants No.60673071,No.60970115,No.60970116,No.61003267partially supported by the National Hi-Tech Research and Department Program of China under Grants No.2006AA01Z442,No.2007AA01Z411
文摘Orthomorphism on F2^n is a kind of elementary pemmtation with good cryptographic properties. This paper proposes a hybrid strategy of Particle Swarm Optimization (PSO) and Sirrmlated Annealing (SA) for finding orthomorphisrm with good cryptographic properties. By experiment based on this strategy, we get some orthorrorphisrm on F2^n = 5, 6, 7, 9, 10) with good cryptographic properties in the open document for the first time, and the optirml orthorrrphism on F found in this paper also does better than the one proposed by Feng Dengguo et al. in stream cipher Loiss in difference uniformity, algebraic degree, algebraic irrarnity and corresponding pernmtation polynomial degree. The PSOSA hybrid strategy for optimizing orthomerphism in this paper makes design of orthorrorphisrm with good cryptographic properties automated, efficient and convenient, which proposes a new approach to design orthornorphisrm.
文摘Applying ontology to describe resource metadata richly in the peer-to-peer environment has become current research trend. In this semantic peer-to-peer environment, indexing semantic element of resource description to support efficient resource location is a difficult and challenging problem. This paper provided a hybrid indexing architecture, which combines local indexing and global indexing. It uses community strategy and semantic routing strategy to organize key layer metadata element and uses DHT (distributed hash table) to index extensional layer metadata element. Compared with related system, this approach is more efficient in resource location and more scalable.
基金Supported by the National High Technology Research and Development Program of China (2007AA04Z193) the National Natural Science Foundation of China (60974008 60704032)
文摘For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude oil blending process. The objective is to keep the property of feedstock, mainly described by the true boiling point (TBP) data, consistent and suitable. Firstly, the mathematical model is established. Then, a heuristically initialized hybrid iterative (HIHI) algorithm based on a two-level optimization structure, in which tabu search (TS) and differential evolution (DE) are used for upper-level and lower-level optimization, respectively, is proposed to get the model solution. Finally, the effectiveness and efficiency of the scheduling strategy is validated via real data from a certain refinery.
基金Supported by the National Natural Science Foundation (70971059) the Liaoning Provincial Programs lbr Science and Technology Development (2011229011)
文摘According to the complex nonlinear relationship between gas emission and its effect factors, and the shortcomings that basic colony algorithm is slow, prone to early maturity and stagnation during the search, we introduced a hybrid optimization strategy into a max-rain ant colony algorithm, then use this improved ant colony algorithm to estimate the scope of RBF network parameters. According to the amount of pheromone of discrete points, the authors obtained from the interval of net- work parameters, ants optimize network parameters. Finally, local spatial expansion is introduced to get further optimization of the network. Therefore, we obtain a better time efficiency and solution efficiency optimization model called hybrid improved max-min ant system (H1-MMAS). Simulation experiments, using these theory to predict the gas emission from the working face, show that the proposed method have high prediction feasibility and it is an effective method to predict gas emission.
基金Project(51465034)supported by the National Natural Science Foundation of China
文摘Based on the log-linear virtual age process, an imperfect preventive maintenance policy for numerical control(NC)machine tools with random maintenance quality is proposed. The proposed model is a combination of the Kijima type virtual age model and the failure intensity adjustment model. Maintenance intervals of the proposed hybrid model are derived when the failure intensity increase factor and the restoration factor are both random variables with uniform distribution. The optimal maintenance policy in infinite time horizon is presented. A numerical example is given when the failures of NC machine tools are described by the log-linear process. Finally, a discussion is presented to show how the optimal results depend on the different cost parameters.
文摘In this paper, a hybrid automatic optimization strategy is proposed for the design of underwater robot lines. Isight is introduced as an integration platform. The construction of this platform is based on the user programming and several commercial software including UG6.0, GAMBIT2.4.6 and FLUENT12.0. An intelligent parameter optimization method, the particle swarm optimization, is incorporated into the platform. To verify the strategy proposed, a simulation is conducted on the underwater robot model 5470, which originates from the DTRC SUBOFF project. With the automatic optimization platform, the minimal resistance is taken as the optimization goal;the wet surface area as the constraint condition; the length of the fore-body, maximum body radius and after-body's minimum radius as the design variables. With the CFD calculation, the RANS equations and the standard turbulence model are used for direct numerical simulation. By analyses of the simulation results, it is concluded that the platform is of high efficiency and feasibility. Through the platform, a variety of schemes for the design of the lines are generated and the optimal solution is achieved. The combination of the intelligent optimization algorithm and the numerical simulation ensures a global optimal solution and improves the efficiency of the searching solutions.
基金supported by the National Natural Science Foundation of China(Grant No.61309005)the Basic and Frontier Research Program of Chongqing(Grant No.cstc2014jcyj A40015)
文摘Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.
基金supported by the National High-Tech R&D Program (863 Program2015AA01A705)in part by Beijing Municipal Commission of Education (The City's Vehicle Sensing Grid Construction Based on Public Transportation Network)
文摘This paper investigates on the base stations(BSs) sleeping control and energy saving in wireless network. The objective is to find the sleeping control and energy saving configuration between total power consumption and average video's quality. On the Software Defined Network(SDN) access network architecture, a type of sleeping control and active BSs' optimal transmitting time strategy is considered, the BS sleeps when there is no active users, and wakes up after a period of vacation time. In this paper, we study the active users grouping strategy, In order to spare more BSs into sleeping mode. Then this paper proposes an active BS transmitting time optimal strategy according to the users' Qo S. In the proposed strategy, the active BSs' transmitting time is minimized in order to save energy. This paper employs the mixed integer-programming model to present this optimization problem. Then we utilized a novel algorithm to save the energy in access networks and also meet the Qo S requirements. Both the analytical and simulation results show that the algorithm can effectively save energy in the access network BSs.
基金Supported by the National Natural Science Foundation of China(No.61173024)
文摘To improve efficiency of search engines, the query result cache has drawn much attention re- cently. According to the query processing and user's query logs locality, a new hybrid result cache strategy which associates with caching heat and worth is proposed to compute cache score in accord- ance with cost-aware strategies. Exactly, query repeated distance and query length factor are utilized to improve the static result policy, and the dynamic policy is adjusted by the caching worth. The hy- brid result cache is implemented in term of the document content and document ids (docIds) se- quence. Based on a score format and the new hybrid structure, an initial algorithm and a new rou- ting algorithm are designed for result cache. Experiments' results show that the improved caching policies decrease the average response time effectively, and increase the system throughput signifi- cantly. By choosing comfortable combination of page cache and docIds cache, the new hybrid cac- hing strategy almost reduces more than 20% of the only cache and docId-only cache. average query time compared with the basic page-
基金Projects(61374140,61673173)supported by the National Natural Science Foundation of ChinaProjects(222201717006,222201714031)supported by the Fundamental Research Funds for the Central Universities,China
文摘A two-step information extraction method is presented to capture the specific index-related information more accurately.In the first step,the overall process variables are separated into two sets based on Pearson correlation coefficient.One is process variables strongly related to the specific index and the other is process variables weakly related to the specific index.Through performing principal component analysis(PCA)on the two sets,the directions of latent variables have changed.In other words,the correlation between latent variables in the set with strong correlation and the specific index may become weaker.Meanwhile,the correlation between latent variables in the set with weak correlation and the specific index may be enhanced.In the second step,the two sets are further divided into a subset strongly related to the specific index and a subset weakly related to the specific index from the perspective of latent variables using Pearson correlation coefficient,respectively.Two subsets strongly related to the specific index form a new subspace related to the specific index.Then,a hybrid monitoring strategy based on predicted specific index using partial least squares(PLS)and T2statistics-based method is proposed for specific index-related process monitoring using comprehensive information.Predicted specific index reflects real-time information for the specific index.T2statistics are used to monitor specific index-related information.Finally,the proposed method is applied to Tennessee Eastman(TE).The results indicate the effectiveness of the proposed method.
文摘A genetic-fuzzy HEV control strategy based on driving cycle recognition (DCR) was built. Six driving cycles were selected to represent different traffic conditions e.g. freeway, urban, suburb. A neural algorithm was used for traffic condition recognition based on ten parameters of each driving cycle. The DCR was utilized for optimization of the HEV control parameters using a genetic-fuzzy approach. A fuzzy logic controller (FLC) was designed to be intelligent to manage the engine to work in the vicinity of its optimal condition. The fuzzy membership function parameters were optimized using the genetic algorithm (GA) for each driving cycle. The result is that the DCR_ fuzzy controller can reduce the fuel consumption by 1. 9%, higher than only CYC _ HWFET optimized fuzzy (0.2%) or CYC _ WVUSUB optimized fuzzy (0.7%). The DCR_ fuzzy method can get the better result than only optimizing one cycle on the complex real traffic conditions.
基金Project(51805200)supported by the National Natural Science Foundation of ChinaProject(20170520096JH)supported by the Science and Technology Development Plan of Jilin Province,ChinaProject(2016YFC0802900)supported by the National Key R&D Program of China
文摘The shift scheduling system of the transmission has an important effect on the dynamic and economic performance of hybrid vehicles. In this work, shift scheduling strategies are developed for parallel hybrid construction vehicles. The effect of power distribution and direction on shift characteristics of the parallel hybrid vehicle with operating loads is evaluated, which must be considered for optimal shift control. A power distribution factor is defined to accurately describe the power distribution and direction in various parallel hybrid systems. This paper proposes a Levenberg-Marquardt algorithm optimized neural network shift scheduling strategy. The methodology contains two objective functions, it is a dynamic combination of a dynamic shift schedule for optimal vehicle acceleration, and an energy-efficient shift schedule for optimal powertrain efficiency. The study is performed on a test bench under typical operating conditions of a wheel loader. The experimental results show that the proposed strategies offer effective and competitive shift performance.
文摘EVs (electric vehicles) have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the high adoption of EVs will impose a burden on the power system, especially for neighborhood level network. In this paper, we propose a mixed control framework for EV charging scheduling to mitigate its impact on the power network. A metric for modeling customer's satisfaction is also proposed to compare the user satisfaction for different algorithms. The impacts of the proposed algorithms on EV charging cost, EV penetration and peak power reduction are evaluated with real data for a neighborhood level network. The simulation results demonstrate the effectiveness of the proposed algorithms.
文摘Multivessel batch distillation(MVBD) is mainly used to separate mixtures with more than two components. In this article, a new operation mode with MVBD is proposed for separation of binary mixtures under total reflux. A mathematic model is setup for the simulation. The proposed operation policy and the regular operation with constant reflux are compared theoretically and experimentally. The results show that the new operation mode has great advantages in time saving and operation flexibility. MVBD presents great potential for separation with high efficiency.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50375033)the National Key Laboratory of Vehicular Transmission(Grant No.51457050105HT0112)
文摘Aimed at the relatively lower energy density and complicated coordinating operation between two power sources,a special energy control strategy is required to maximize the fuel saving potential.Then a new type of configuration for hydrostatic transmission hybrid vehicles(PHHV) and the selection criterion for important components are proposed.Based on the optimization of planet gear transmission ratio and the analysis of optimal energy distribution for the proposed PHHV on a representative urban driving cycle,a fuzzy torque control strategy and a braking energy regeneration strategy are designed and developed to realize the real-time control of energy for the proposed PHHV.Simulation results demonstrate that the energy control strategy effectively improves the fuel economy of PHHV.
基金Project(50775225) supported by the National Natural Science Foundation of ChinaProjects(CSTC, 2008AC6097, 2008BA6025) supported by National Natural Science Foundation of Chongqing, China
文摘A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.
基金Supported by the National Basic Research Program of China ( No. 2007CB714007) , the National Natural Science Foundation of China ( No. 50975149) , and the Important National Science & Technology Specific Projects of China (No. 2009ZX04014-.035, 2009ZX04001-042-02).
文摘This paper mainly analyzes a hybrid position/force control strategy and experiment of a six-cable driven parallel manipulator for a forty-meter aperture radio telescope. Through the establishments of a kinematic model, a catenary model and a cable-force characteristics model, a basic method is presented based on preventing the pseudo-drag problem of a flexible cable and realizing the hybrid position/force control for a six-cable driven parallel manipulator, and a hybrid position/force control system is developed. Some specific experiments in two typical velocities for astronomical observations are carried out. Experimental results show that the tracking accuracy is related to the speed of the movement. The desired tracking accuracy of the support system is achieved through an effective hybrid position/force control strategy, the cable forces are controlled effectively, and the pseudo-drag problem of flexible cable is solved. This study establishes the foundation of achieving the harmonious movement of the six-cable driven parallel manipulator, A-B rotating platform and the Stewart fine tuninz olatform.
基金Project(2013BAF07B02)supported by National Science and Technology Support Program of China
文摘After analyzing the working condition of the conventional diesel forklift,an energy recovery system in hybrid forklift is considered and its simulation model is built.Then,the control strategy for the proposed energy recovery system is discussed,which is validated and evaluated by simulation.The simulation results show that the proposed control strategy can achieve balance of the power and keep the state of charge(SOC) of ultra capacitor in a reasonable range,and the fuel consumption can be reduced by about 20.8% compared with the conventional diesel forklift.Finally,the feasibility of the simulation results is experimentally verified based on the lifting energy recovery system.