In the present study,split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated.CuO nanoparticles with the average particle size of 15 nm were added partially t...In the present study,split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated.CuO nanoparticles with the average particle size of 15 nm were added partially to self compacting concrete and split tensile strength of the specimens has been measured.The results indicate that CuO nanoparticles are able to improve the split tensile strength of self compacting concrete and recover the negative effects of polycarboxylate superplasticizer on split tensile strength.CuO nanoparticle as a partial replacement of cement up to 4 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early ages of hydration.The increase of the CuO nanoparticles more than 4 wt% causes the decrease of the split tensile strength because of unsuitable dispersion of nanoparticles in the concrete matrix.Accelerated peak appearance in conduction calorimetry tests,more weight loss in thermogravimetric analysis and more rapid appearance of related peaks to hydrated products in X-ray diffraction（XRD） results all also indicate that CuO nanoparticles up to4 wt% could improve the mechanical and physical properties of the specimens.Finally,CuO nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and few-harm pores.展开更多
The application of numerical weather prediction （NWP） products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical...The application of numerical weather prediction （NWP） products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical ensemble precipitation forecasts in the TIGGE database were evaluated using deterministic, dichotomous （yes/no）, and probabilistic techniques over Iran for the period 2008-16. Thirteen rain gauges spread over eight homogeneous precipitation regimes were selected for evaluation. The Inverse Distance Weighting and Kriging methods were adopted for interpolation of the prediction values, downscaled to the stations at lead times of one to three days. To enhance the forecast quality, NWP values were post-processed via Bayesian Model Averaging. The results showed that ECMWF had better scores than other products. However, products of all centers underestimated precipitation in high precipitation regions while overestimating precipitation in other regions. This points to a systematic bias in forecasts and demands application of bias correction techniques. Based on dichotomous evaluation, NCEP did better at most stations, although all centers overpredicted the number of precipitation events. Compared to those of ECMWF and NCER UKMO yielded higher scores in mountainous regions, but performed poorly at other selected stations. Furthermore, the evaluations showed that all centers had better skill in wet than in dry seasons. The quality of post-processed predictions was better than those of the raw predictions. In conclusion, the accuracy of the NWP predictions made by the selected centers could be classified as medium over Iran, while post-processing of predictions is recommended to improve the quality.展开更多
In the present study, fracture toughness of functionally graded steels in crack divider configuration has been modeled. By utilizing plain carbon and austenitic stainless steels slices with various thicknesses and arr...In the present study, fracture toughness of functionally graded steels in crack divider configuration has been modeled. By utilizing plain carbon and austenitic stainless steels slices with various thicknesses and arrangements as electroslag remelting electrodes, functionally graded steels were produced. The fracture toughness of the functionally graded steels in crack divider configuration has been found to depend on the composites＇ type together with the volume fraction and the position of the containing phases. According to the area under stress-strain curve of each layer in the functionally graded steels, a mathematical model has been presented for predicting fracture toughness of composites by using the rule of mixtures. The fracture toughness of each layer has been modified according to the position of that layer where for the edge layers, net plane stress condition was supposed and for the central layers, net plane strain condition was presumed. There is a good agreement between experimental results and those acquired from the analytical model.展开更多
Time for single vehicle combat preparation(TSVCP) is an important characteristic parameter for the operational support feature of armored vehicle. During the development phase, how to validate the TSVCP of armored veh...Time for single vehicle combat preparation(TSVCP) is an important characteristic parameter for the operational support feature of armored vehicle. During the development phase, how to validate the TSVCP of armored vehicle through analytic method is a difficult issue in analysis and validation of vehicle supportability.This paper uses Monte Carlo approach and builds a working model for single vehicle combat preparation(SVCP)of armored vehicle, thus realizes the prediction and analysis of the TSVCP of armored vehicle, and finally validates the effectiveness of the approach by example.展开更多
For the disadvantages of analyzing system reliability using common Bayes method,an evaluation method based on improved Bayes-Bootstrap method is presented.Firstly,the data obliteration problem existing in traditional ...For the disadvantages of analyzing system reliability using common Bayes method,an evaluation method based on improved Bayes-Bootstrap method is presented.Firstly,the data obliteration problem existing in traditional Bayes method is analyzed,then an improved sampling arithmetic is proposed on the foundation of an experience function.Finally,effectiveness of this method is proved by an example.The simulating result shows that this method is more accurate than common Bayes method.展开更多
In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45#...In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.展开更多
Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper ...Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper with fail-safe capability is designed.Firstly,the mathematical model of damping moment is deduced based on the parallel-plate model and Bingham model of MR fluids.Secondly,some influence factors of damping adjustable multiple are analyzed to provide some ways for augmenting the damping adjustable multiple under the condition of keeping initial damping moment invariable.Finally,the magnetic circuit is designed,and magnetic field distribution is simulated with the magnetic finite element analysis software-ANSOFT.The theory and simulation results confirm that the damping adjustable range of vane MRF damper can meet the requirement of heavy vehicle semi-active suspension system.展开更多
The reliability assessment model of k /N system is built based on Copula function theory considering the failure correlativity existing among components,and then a simulation strategy is presented on the foundation of...The reliability assessment model of k /N system is built based on Copula function theory considering the failure correlativity existing among components,and then a simulation strategy is presented on the foundation of agent technique.The components and equipment entity model are designed according to the modeling technique above to describe the operation relationship during the mission phase,and then the simulation system for the assessment of product reliability is completed.And at last,an example is given with different material support programs.The research result has shown that the relevance existing in components has effect on the confirmation and optimization of maintenance strategy.展开更多
The mission reliability assessment plays a great role in logistics planning and supporting resource optimization of complex system.But the current problem,which is difficult to solve,is how to model and analyze the ch...The mission reliability assessment plays a great role in logistics planning and supporting resource optimization of complex system.But the current problem,which is difficult to solve,is how to model and analyze the characters of system reliability under the complex mission profile.In order to solve the problem,an agentbased simulation method was used to assess reliability for complex systems with various random working conditions.A multi-working condition simulation agent(MA)was designed and used to simulate the random transferring process of working conditions of system,and it cooperated with system simulation agents(SAs)and unit simulation agents(UAs)to realize system mission reliability(MR)simulation.Through simulation experiments,effect of multiple working conditions mission on the reliability of system was analyzed by comparing with the basic reliability condition.Feasibility and efficiency of the method were proved through simulation experiments of the case system.The research result provides a viable and useful method and a solution for MR analysis and assessment of complex systems in multi-working conditions,which can help to evaluate the reliability of operating system orienting to the practical mission and environment,and it is meaningful for the reliability analysis and the design of complex systems.展开更多
The divisions of the typical army maintenance organization's tasks in wartime are discussed.Two distribution models of armored equipment maintenance objects are presented:one is calculated by maintenance workload ...The divisions of the typical army maintenance organization's tasks in wartime are discussed.Two distribution models of armored equipment maintenance objects are presented:one is calculated by maintenance workload and the other is calculated by maintenance time.Combined with the division of maintenance time limit for the land force's maintenance institutions,the probability distribution of the maintenance object which is produced from the typical armored equipment's technical failure and battle damage in every repair organization is obtained.A new way for the study of the distribution law of battle damage is supplied,which has an active function to improve the accuracy of technical support program.展开更多
The paper deals with systems suffered from gradual deterioration. To avoid functional failures and disastrous consequences, such systems should be monitored and preventively maintained. And to promote the maintenance ...The paper deals with systems suffered from gradual deterioration. To avoid functional failures and disastrous consequences, such systems should be monitored and preventively maintained. And to promote the maintenance effectiveness, an unequal time-interval maintenance policy was brought forward to substitute fixedinterval preventive maintenance strategy. At the same time, preventive and corrective maintenance actions are both assumed to be imperfect, and their impact on the system is expressed by the increment of failure rate. The case study shown that the unequal time-interval maintenance policy proposed in the paper is of help to promote the availability of the system.展开更多
The influencing factors of the equipment support activity process have the characteristics of nonlinearity, high dimension, many constraints, random uncertainty and fuzzy uncertainty. Monte Carlo method can solve the ...The influencing factors of the equipment support activity process have the characteristics of nonlinearity, high dimension, many constraints, random uncertainty and fuzzy uncertainty. Monte Carlo method can solve the above problems commendably. This paper analyzes the main equipment support activity process and establishes the sampling plan and simulation model of the medium maintenance process based on Monte Carlo method, and the simulation result verifies a fact that the medium maintenance time can be effectively reduced when parallel operation on some procedures is used. It has a practical value and can give good advice to achieve the capability of equipment supportability.展开更多
The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment mate...The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment materiel support. Firstly, the military and function demands of armored equipment materiel support grid are analyzed. Besides, according to the function demand, the system structure of armored equipment materiel support grid is designed. Finally, the organizational structure of armored equipment materiel support grid is established in this paper based on actual armored equipment materiel support.展开更多
In hierarchical networks, nodes are separated to play different roles such as CHs and cluster members. Each CH collects data from the cluster members within its cluster, aggregates the data and then transmits the data...In hierarchical networks, nodes are separated to play different roles such as CHs and cluster members. Each CH collects data from the cluster members within its cluster, aggregates the data and then transmits the data to the sink. Each algorithm that is used for packet routing in quality of service (QoS) based applications should be able to establish a tradeoffs between end to end delay parameter and energy consumption. Therefore, enabling QoS applications in sensor networks requires energy and QoS awareness in different layers of the protocol stack. We propose a QoS based and Energy aware Multi-path Hierarchical Routing Algorithm in wireless sensor networks namely QEMH. In this protocol, we try to satisfy the QoS requirements with the minimum energy via hierarchical methods. Our routing protocol includes two phase. In first phase, performs cluster heads election based on two parameters: node residual energy and node distance to sink. In second phase, accomplishes routes discovery using multiple criteria such as residual energy, remaining buffer size, signal-to-noise ratio and distance to sink. When each node detect an event can send data to the CH as single hop and CH to the sink along the paths. We use a weighted traffic allocation strategy to distribute the traffic amongst the available paths to improve the end to end delay and throughput. In this strategy, the CH distributes the traffic between the paths according to the end to end delay of each path. The end to end delay of each path is obtained during the paths discovery phase. QEMH maximizes the network lifetime as load balancing that causes energy consume uniformly throughout the network. Furthermore employs a queuing model to handle both real-time and non-real-time traffic. By means of simulations, we evaluate and compare the performance of our routing protocol with the MCMP and EAP protocols. Simulation results show that our proposed protocol is more efficient than those protocols in providing QoS requirements and minimizing energy consumption.展开更多
In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have be...In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models are arranged in a format of 8 input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the neural networks and genetic programming models the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles. It has been found that NN and GEP models will be valid within the ranges of variables. In neural networks model, as the training and testing ended when minimum error norm of network was gained, the best results were obtained and in genetic programming model, when 4 genes were selected to construct the model, the best results were acquired. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.展开更多
Transmission pricing has become a major issue in the discussions about the deregulated electricity markets. Consequently, open access to the transmission system is one of the basic topics to allow competition among pa...Transmission pricing has become a major issue in the discussions about the deregulated electricity markets. Consequently, open access to the transmission system is one of the basic topics to allow competition among participants in the energy market. Transmission costs have an important impact on relative competition among participants in the energy market as well as on short- and long-term economic efficiencies of the whole electricity industry, although they represent only close to 10% of the energy market price. This paper deals with the design and tests of a transmission pricing method based on the optimal circuit prices derived from the economically adapted network （EAN）. Prices derived from the EAN have the advantage of being in tune with the maximum revenue allowed to the owner of transmission assets and simplifying the optimal allocation of transmission costs among participants. Beginning from the conceptual design, the proposed method is tested on a three-bus network and on the IEEE 24-bus reliability test system.展开更多
The Journal Editorial Officehas retracted this articlebecause it shows significantoverlapwith a numberofarticles including those that were under consideration at the same time[1-4].Additionally,the article shows evide...The Journal Editorial Officehas retracted this articlebecause it shows significantoverlapwith a numberofarticles including those that were under consideration at the same time[1-4].Additionally,the article shows evidence of peer reviewmanipulation.The Publisher has not been able to obtain a current email address for both authors.展开更多
The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfo...The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfort.In this study,the effect of ventilation realized using a wind tower on the thermal quality of a classroom was investigated.In the study,two popular models(unidirectional and multidirectional wind tower)were studied,and the model that provided more ergonomic ventilation to sitting users based on climate conditions of the province of Trabzon(Turkey)during the month of August was determined.The more efficient model was studied further.Some dimensional changes in width,height,and shelf height were applied to it to find a model that provided more comfort for the used thermal conditions.The models were modelled and simulated using ANSYS FLUENT.Velocity distributions were generated to ease the interpretation of the results.With the calculated average wind speeds in different regions in the classroom,the thermal sensation in the space was evaluated.Furthermore,the thermal perception of users of the retained model was evaluated by entering thermal comfort parameter values calculated for the relevant region into the CBE thermal comfort tool available online.The change in the dimensional features of the wind tower had an impact on wind tower performance.Ventilation provided by wind towers under the thermal conditions of Trabzon in August often caused thermal discomfort.展开更多
文摘In the present study,split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated.CuO nanoparticles with the average particle size of 15 nm were added partially to self compacting concrete and split tensile strength of the specimens has been measured.The results indicate that CuO nanoparticles are able to improve the split tensile strength of self compacting concrete and recover the negative effects of polycarboxylate superplasticizer on split tensile strength.CuO nanoparticle as a partial replacement of cement up to 4 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early ages of hydration.The increase of the CuO nanoparticles more than 4 wt% causes the decrease of the split tensile strength because of unsuitable dispersion of nanoparticles in the concrete matrix.Accelerated peak appearance in conduction calorimetry tests,more weight loss in thermogravimetric analysis and more rapid appearance of related peaks to hydrated products in X-ray diffraction（XRD） results all also indicate that CuO nanoparticles up to4 wt% could improve the mechanical and physical properties of the specimens.Finally,CuO nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and few-harm pores.
文摘The application of numerical weather prediction （NWP） products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical ensemble precipitation forecasts in the TIGGE database were evaluated using deterministic, dichotomous （yes/no）, and probabilistic techniques over Iran for the period 2008-16. Thirteen rain gauges spread over eight homogeneous precipitation regimes were selected for evaluation. The Inverse Distance Weighting and Kriging methods were adopted for interpolation of the prediction values, downscaled to the stations at lead times of one to three days. To enhance the forecast quality, NWP values were post-processed via Bayesian Model Averaging. The results showed that ECMWF had better scores than other products. However, products of all centers underestimated precipitation in high precipitation regions while overestimating precipitation in other regions. This points to a systematic bias in forecasts and demands application of bias correction techniques. Based on dichotomous evaluation, NCEP did better at most stations, although all centers overpredicted the number of precipitation events. Compared to those of ECMWF and NCER UKMO yielded higher scores in mountainous regions, but performed poorly at other selected stations. Furthermore, the evaluations showed that all centers had better skill in wet than in dry seasons. The quality of post-processed predictions was better than those of the raw predictions. In conclusion, the accuracy of the NWP predictions made by the selected centers could be classified as medium over Iran, while post-processing of predictions is recommended to improve the quality.
文摘In the present study, fracture toughness of functionally graded steels in crack divider configuration has been modeled. By utilizing plain carbon and austenitic stainless steels slices with various thicknesses and arrangements as electroslag remelting electrodes, functionally graded steels were produced. The fracture toughness of the functionally graded steels in crack divider configuration has been found to depend on the composites＇ type together with the volume fraction and the position of the containing phases. According to the area under stress-strain curve of each layer in the functionally graded steels, a mathematical model has been presented for predicting fracture toughness of composites by using the rule of mixtures. The fracture toughness of each layer has been modified according to the position of that layer where for the edge layers, net plane stress condition was supposed and for the central layers, net plane strain condition was presumed. There is a good agreement between experimental results and those acquired from the analytical model.
文摘Time for single vehicle combat preparation(TSVCP) is an important characteristic parameter for the operational support feature of armored vehicle. During the development phase, how to validate the TSVCP of armored vehicle through analytic method is a difficult issue in analysis and validation of vehicle supportability.This paper uses Monte Carlo approach and builds a working model for single vehicle combat preparation(SVCP)of armored vehicle, thus realizes the prediction and analysis of the TSVCP of armored vehicle, and finally validates the effectiveness of the approach by example.
文摘For the disadvantages of analyzing system reliability using common Bayes method,an evaluation method based on improved Bayes-Bootstrap method is presented.Firstly,the data obliteration problem existing in traditional Bayes method is analyzed,then an improved sampling arithmetic is proposed on the foundation of an experience function.Finally,effectiveness of this method is proved by an example.The simulating result shows that this method is more accurate than common Bayes method.
文摘In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.
基金the National Defence Sci-Tech Key Lab Fundation(51457040204BQ0102)
文摘Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper with fail-safe capability is designed.Firstly,the mathematical model of damping moment is deduced based on the parallel-plate model and Bingham model of MR fluids.Secondly,some influence factors of damping adjustable multiple are analyzed to provide some ways for augmenting the damping adjustable multiple under the condition of keeping initial damping moment invariable.Finally,the magnetic circuit is designed,and magnetic field distribution is simulated with the magnetic finite element analysis software-ANSOFT.The theory and simulation results confirm that the damping adjustable range of vane MRF damper can meet the requirement of heavy vehicle semi-active suspension system.
文摘The reliability assessment model of k /N system is built based on Copula function theory considering the failure correlativity existing among components,and then a simulation strategy is presented on the foundation of agent technique.The components and equipment entity model are designed according to the modeling technique above to describe the operation relationship during the mission phase,and then the simulation system for the assessment of product reliability is completed.And at last,an example is given with different material support programs.The research result has shown that the relevance existing in components has effect on the confirmation and optimization of maintenance strategy.
文摘The mission reliability assessment plays a great role in logistics planning and supporting resource optimization of complex system.But the current problem,which is difficult to solve,is how to model and analyze the characters of system reliability under the complex mission profile.In order to solve the problem,an agentbased simulation method was used to assess reliability for complex systems with various random working conditions.A multi-working condition simulation agent(MA)was designed and used to simulate the random transferring process of working conditions of system,and it cooperated with system simulation agents(SAs)and unit simulation agents(UAs)to realize system mission reliability(MR)simulation.Through simulation experiments,effect of multiple working conditions mission on the reliability of system was analyzed by comparing with the basic reliability condition.Feasibility and efficiency of the method were proved through simulation experiments of the case system.The research result provides a viable and useful method and a solution for MR analysis and assessment of complex systems in multi-working conditions,which can help to evaluate the reliability of operating system orienting to the practical mission and environment,and it is meaningful for the reliability analysis and the design of complex systems.
文摘The divisions of the typical army maintenance organization's tasks in wartime are discussed.Two distribution models of armored equipment maintenance objects are presented:one is calculated by maintenance workload and the other is calculated by maintenance time.Combined with the division of maintenance time limit for the land force's maintenance institutions,the probability distribution of the maintenance object which is produced from the typical armored equipment's technical failure and battle damage in every repair organization is obtained.A new way for the study of the distribution law of battle damage is supplied,which has an active function to improve the accuracy of technical support program.
文摘The paper deals with systems suffered from gradual deterioration. To avoid functional failures and disastrous consequences, such systems should be monitored and preventively maintained. And to promote the maintenance effectiveness, an unequal time-interval maintenance policy was brought forward to substitute fixedinterval preventive maintenance strategy. At the same time, preventive and corrective maintenance actions are both assumed to be imperfect, and their impact on the system is expressed by the increment of failure rate. The case study shown that the unequal time-interval maintenance policy proposed in the paper is of help to promote the availability of the system.
基金the Special Research Fund for the Research on Armored Vehicle Supportability Requirement Analysis(No.51319050302)
文摘The influencing factors of the equipment support activity process have the characteristics of nonlinearity, high dimension, many constraints, random uncertainty and fuzzy uncertainty. Monte Carlo method can solve the above problems commendably. This paper analyzes the main equipment support activity process and establishes the sampling plan and simulation model of the medium maintenance process based on Monte Carlo method, and the simulation result verifies a fact that the medium maintenance time can be effectively reduced when parallel operation on some procedures is used. It has a practical value and can give good advice to achieve the capability of equipment supportability.
文摘The core of grid technology is just to solve the problem of resource share and to eliminate information island and resource island. Thus, it is a perfect approach to apply the grid technology to armored equipment materiel support. Firstly, the military and function demands of armored equipment materiel support grid are analyzed. Besides, according to the function demand, the system structure of armored equipment materiel support grid is designed. Finally, the organizational structure of armored equipment materiel support grid is established in this paper based on actual armored equipment materiel support.
文摘In hierarchical networks, nodes are separated to play different roles such as CHs and cluster members. Each CH collects data from the cluster members within its cluster, aggregates the data and then transmits the data to the sink. Each algorithm that is used for packet routing in quality of service (QoS) based applications should be able to establish a tradeoffs between end to end delay parameter and energy consumption. Therefore, enabling QoS applications in sensor networks requires energy and QoS awareness in different layers of the protocol stack. We propose a QoS based and Energy aware Multi-path Hierarchical Routing Algorithm in wireless sensor networks namely QEMH. In this protocol, we try to satisfy the QoS requirements with the minimum energy via hierarchical methods. Our routing protocol includes two phase. In first phase, performs cluster heads election based on two parameters: node residual energy and node distance to sink. In second phase, accomplishes routes discovery using multiple criteria such as residual energy, remaining buffer size, signal-to-noise ratio and distance to sink. When each node detect an event can send data to the CH as single hop and CH to the sink along the paths. We use a weighted traffic allocation strategy to distribute the traffic amongst the available paths to improve the end to end delay and throughput. In this strategy, the CH distributes the traffic between the paths according to the end to end delay of each path. The end to end delay of each path is obtained during the paths discovery phase. QEMH maximizes the network lifetime as load balancing that causes energy consume uniformly throughout the network. Furthermore employs a queuing model to handle both real-time and non-real-time traffic. By means of simulations, we evaluate and compare the performance of our routing protocol with the MCMP and EAP protocols. Simulation results show that our proposed protocol is more efficient than those protocols in providing QoS requirements and minimizing energy consumption.
文摘In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models are arranged in a format of 8 input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the neural networks and genetic programming models the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles. It has been found that NN and GEP models will be valid within the ranges of variables. In neural networks model, as the training and testing ended when minimum error norm of network was gained, the best results were obtained and in genetic programming model, when 4 genes were selected to construct the model, the best results were acquired. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.
基金The first author gratefully acknowledges the support from Science and Research Branch, Islamic Azad University, Tehran, Iran.
文摘Transmission pricing has become a major issue in the discussions about the deregulated electricity markets. Consequently, open access to the transmission system is one of the basic topics to allow competition among participants in the energy market. Transmission costs have an important impact on relative competition among participants in the energy market as well as on short- and long-term economic efficiencies of the whole electricity industry, although they represent only close to 10% of the energy market price. This paper deals with the design and tests of a transmission pricing method based on the optimal circuit prices derived from the economically adapted network （EAN）. Prices derived from the EAN have the advantage of being in tune with the maximum revenue allowed to the owner of transmission assets and simplifying the optimal allocation of transmission costs among participants. Beginning from the conceptual design, the proposed method is tested on a three-bus network and on the IEEE 24-bus reliability test system.
文摘The Journal Editorial Officehas retracted this articlebecause it shows significantoverlapwith a numberofarticles including those that were under consideration at the same time[1-4].Additionally,the article shows evidence of peer reviewmanipulation.The Publisher has not been able to obtain a current email address for both authors.
文摘The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfort.In this study,the effect of ventilation realized using a wind tower on the thermal quality of a classroom was investigated.In the study,two popular models(unidirectional and multidirectional wind tower)were studied,and the model that provided more ergonomic ventilation to sitting users based on climate conditions of the province of Trabzon(Turkey)during the month of August was determined.The more efficient model was studied further.Some dimensional changes in width,height,and shelf height were applied to it to find a model that provided more comfort for the used thermal conditions.The models were modelled and simulated using ANSYS FLUENT.Velocity distributions were generated to ease the interpretation of the results.With the calculated average wind speeds in different regions in the classroom,the thermal sensation in the space was evaluated.Furthermore,the thermal perception of users of the retained model was evaluated by entering thermal comfort parameter values calculated for the relevant region into the CBE thermal comfort tool available online.The change in the dimensional features of the wind tower had an impact on wind tower performance.Ventilation provided by wind towers under the thermal conditions of Trabzon in August often caused thermal discomfort.
