The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. B...The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed.Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance,and it establishes a theoretical basis for studies and engineering applications.展开更多
Many models about the change of pollutants have been established for the estimating, assessing and planning about water quality. Because of the complicated influential factors, no suitable and convenient model has eve...Many models about the change of pollutants have been established for the estimating, assessing and planning about water quality. Because of the complicated influential factors, no suitable and convenient model has ever been practised to predict the variation of active acidity in natural waters. The author recently raised a primary and simple method.展开更多
The ordered event model is improved to describe serial production lines with limited buffer sizes. The improved model hasthe same computational burden as the original one and can be constrUcted directly according to g...The ordered event model is improved to describe serial production lines with limited buffer sizes. The improved model hasthe same computational burden as the original one and can be constrUcted directly according to given principles. Several simulationexamples are cited to verify this improved model. Extensions and open problems are also indicated. By means of this new model, serialProduotion lines with limitations of resources can be stUdied analytically.展开更多
In this paper, we study the interconnect buffer and wiresizing optimization problem under a distributed RLC model to optimize not just area and delay, but also crosstalk for RLC circuit with non-monotone signal respon...In this paper, we study the interconnect buffer and wiresizing optimization problem under a distributed RLC model to optimize not just area and delay, but also crosstalk for RLC circuit with non-monotone signal response. We present a new multiobjective genetic algorithm（MOGA） which uses a single objective sorting（SOS） method for constructing the non-dominated set to solve this multi-objective interconnect optimization problem. The MOGA/SOS optimal algorithm provides a smooth trade-off among signal delay, wave form, and routing area. Furthermore, we use a new method to calculate the lower bound of crosstalk. Extensive experimental results show that our algorithm is scalable with problem size. Furthermore, compared to the solution based on an Elmore delay model, our solution reduces the total routing area by up to 30%, the delay to the critical sinks by up to 25%, while further improving crosstalk up to 25.73% on average.展开更多
Controlling soil erosion and the transport and deposition of suspended sediment to receiving waters, especially in relation to the modifying influences of, and interplay between, climate and land-use alterations, is e...Controlling soil erosion and the transport and deposition of suspended sediment to receiving waters, especially in relation to the modifying influences of, and interplay between, climate and land-use alterations, is essential for effective watershed management. The Atlantic Canada—New England region is expected to experience elevated rainfall erosivity due to climate change over the next century. Using the projected higher precipitation amounts of 5% and 10% for future scenarios of 5 and 25 years for the region, and a spatially-explicit, integrated (GIS, RUSLE) model for a rural watershed in Nova Scotia, predicted increases in total erosion rates of 4.9 and 9.9%, respectively. Modelled scenarios altering buffer strips based on either consistent or slope-variable widths between 30 m (the legal requirement) to 90 m were found to correspond to reductions in predicted total watershed erosion rates from 11% to 32%. Assuming and extending the 1:1 concordance between projected precipitation and estimated soil erosion for this particular watershed into the more distant future of 26 to 55 years, suggests that the 25% increase in soil erosion predicted over this period would have to be offset by expanding the protective buffer strips to a consistent width of 70 m. Adoption of such a protective management scheme would subsume 19% of the terrestrial area of the study watershed and thus consequent reductions in land available for agricultural production and timber harvest.展开更多
The paper presents a prototype of virtual decoder of the transport stream＇s system target decoder （T-STD）. By connecting the coding model and decoding model, and feeding the overflow of decoding buffer back to cont...The paper presents a prototype of virtual decoder of the transport stream＇s system target decoder （T-STD）. By connecting the coding model and decoding model, and feeding the overflow of decoding buffer back to control coding, we have got a self-adaptive coding model, and propose an algorithm of muhiplexing multiple elementary streams to a transport stream based on the principle of virtual buffer controlling strategy. The transport stream （TS） which uses this method passes the test of software unzipping and set top-box （STB） playing, and all of the analyzing parameters which are detected by code analyzer accord with the standard of MPEG-2. Some problems that playing time becomes longer and mul tiple TS streaming can not be fit for all the players are also analyzed.展开更多
As two independent problems,scheduling for parts fabrication line and sequencing for mixed-model assembly line have been addressed respectively by many researchers.However,these two problems should be considered simul...As two independent problems,scheduling for parts fabrication line and sequencing for mixed-model assembly line have been addressed respectively by many researchers.However,these two problems should be considered simultaneously to improve the efficiency of the whole fabrication/assembly systems.By far,little research effort is devoted to sequencing problems for mixed-model fabrication/assembly systems.This paper is concerned about the sequencing problems in pull production systems which are composed of one mixed-model assembly line with limited intermediate buffers and two flexible parts fabrication flow lines with identical parallel machines and limited intermediate buffers.Two objectives are considered simultaneously：minimizing the total variation in parts consumption in the assembly line and minimizing the total makespan cost in the fabrication/assembly system.The integrated optimization framework,mathematical models and the method to construct the complete schedules for the fabrication lines according to the production sequences for the first stage in fabrication lines are presented.Since the above problems are non-deterministic polynomial-hard（NP-hard）,a modified multi-objective genetic algorithm is proposed for solving the models,in which a method to generate the production sequences for the fabrication lines from the production sequences for the assembly line and a method to generate the initial population are put forward,new selection,crossover and mutation operators are designed,and Pareto ranking method and sharing function method are employed to evaluate the individuals＇ fitness.The feasibility and efficiency of the multi-objective genetic algorithm is shown by computational comparison with a multi-objective simulated annealing algorithm.The sequencing problems for mixed-model production systems can be solved effectively by the proposed modified multi-objective genetic algorithm.展开更多
A better understanding of the mechanisms that control nutrient acquisition in the context of plant and ecosystem responses to climate change is needed. Mechanistic nutrient uptake models provide a means to investigate...A better understanding of the mechanisms that control nutrient acquisition in the context of plant and ecosystem responses to climate change is needed. Mechanistic nutrient uptake models provide a means to investigate some of the impacts of temperature change on soil nutrient supply and root uptake kinetics through the simulation of key soil and plant processes. The NST 3.0 model, in combination with literature values on plant and soil parameters from a red spruce (Picea rubens L.) site in the southern Appalachians, was used to conduct a series of model simulations focused on the combined effects of changes to the maximal rate of nutrient influx at high concentrations (Imax), root growth rate (k), concentration of nutrient occurring in the soil solution (Cli), and the ability of the soil solid phase to buffer changes to the soil solution nutrient concentration (b). Previous research has indicated that these four parameters are responsive to changes in root zone temperature. Simulated uptake of NH4 increased by a factor of up to 2.6 in response to increases in soil temperature of 1°C to 5°C. The model also projected an increase in P uptake coupled with up to an 80% reduction in solution P concentration in response to a 1°C -5°C increase over a 147-d simulation period. These hypothetical changes, if validated, have interesting implications for plant growth and competition and point to a need for additional studies to better define the impacts of soil temperature on soil nutrient supply and root uptake.展开更多
The formation of calcium phosphate phases is extremely important in a biomedical engineering context. These phosphates are used in many applications, such as grafts, drug-delivery processes and evaluation of the bioac...The formation of calcium phosphate phases is extremely important in a biomedical engineering context. These phosphates are used in many applications, such as grafts, drug-delivery processes and evaluation of the bioactivity of metallic surfaces. Considering this scenario, it is useful to evaluate the thermodynamic conditions for the precipitation of phosphates of biomedical interest, mainly hydroxyapatite. In this work, we investigate the effects of two important factors using a thermodynamic framework: 1) carbon dioxide partial pressure;and 2) buffer type (2-Amino-2-hydroxy- methyl-propane-1,3-diol, known as TRIS and 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid, also called HEPES), on the driving force behind the precipitation of calcium phosphates in simulated body fluids. The in silico results show that the pH value is governed by carbon dioxide content, as expected to occur in vivo. Moreover, the buffers can deplete the free calcium available in solution and, consequently, can cause difficulties in the calcium phosphate precipitation.展开更多
In Italy high-quality vines are grown on sloping fields where pesticide runoff to surface water is possible and vegetated buffers are suggested as mitigation measure. Spinosad is an insecticide used to control pests i...In Italy high-quality vines are grown on sloping fields where pesticide runoff to surface water is possible and vegetated buffers are suggested as mitigation measure. Spinosad is an insecticide used to control pests in vineyards. For regulatory purposes, FOCUS modelling is used to calculate pesticides runoff reduction provided by a vegetated buffer, but there is an urgent need for field-based results. A field trial with artificial runoff was performed in September 2017 in Northern Italy to evaluate the efficiency of a grassed buffer to reduce spinosad runoff. Trial conditions were based on FOCUS scenarios but made worse to draw prudent conclusions. For the first time in Italy, the trial was conducted according to Good Laboratory Practices to increase reliability of results and reproducibility of the study for regulatory purposes. Five plots were tested, each simulating a grassed buffer of 12 m length on a slope of 10% - 13%. The artificial runoff was 200 mm in 3 hours and rainfall pre- and during runoff was 45 mm. Results show that the 12 m buffer completely retained runoff and effectively mitigated runoff concentration, and mean reduction of spinosad concentration was 59%. A width effect exists, and every 6.5 m of buffer reduces concentration by 50%. Comparison of field results with FOCUS modelling shows that both VFSMod and LM models provide acceptable estimation of runoff reduction for a 5 m buffer, while LM seems more precise. For a 10 m buffer the VFSMod is very accurate, while LM underestimates reduction observed in the field.展开更多
The quality of experience（ QoE） evaluation model for voice over IP（ VoI P） service is studied to analyze the impact of network parameters on voice quality and monitor voice quality in real-time for operators.First...The quality of experience（ QoE） evaluation model for voice over IP（ VoI P） service is studied to analyze the impact of network parameters on voice quality and monitor voice quality in real-time for operators.Firstly,the influence of some network parameters on the voice quality of VoI P is investigated. Then,a simulation platform for VoI P transmission is built to collect voice data under different network enviornments. According to the simulation results,a new mapping model between these arguments and VoI P voice quality is deduced. Finally,the accuracy of this voice quality evaluation model is examined and the results demanstrate that it has high reliability and feasibility.展开更多
基金supported by the National Natural Science Foundation of China (Grant 51375035)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant 20121102110021)
文摘The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed.Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance,and it establishes a theoretical basis for studies and engineering applications.
文摘Many models about the change of pollutants have been established for the estimating, assessing and planning about water quality. Because of the complicated influential factors, no suitable and convenient model has ever been practised to predict the variation of active acidity in natural waters. The author recently raised a primary and simple method.
文摘The ordered event model is improved to describe serial production lines with limited buffer sizes. The improved model hasthe same computational burden as the original one and can be constrUcted directly according to given principles. Several simulationexamples are cited to verify this improved model. Extensions and open problems are also indicated. By means of this new model, serialProduotion lines with limitations of resources can be stUdied analytically.
基金Supported by the National Natural Science Foundation of China (90307017)
文摘In this paper, we study the interconnect buffer and wiresizing optimization problem under a distributed RLC model to optimize not just area and delay, but also crosstalk for RLC circuit with non-monotone signal response. We present a new multiobjective genetic algorithm（MOGA） which uses a single objective sorting（SOS） method for constructing the non-dominated set to solve this multi-objective interconnect optimization problem. The MOGA/SOS optimal algorithm provides a smooth trade-off among signal delay, wave form, and routing area. Furthermore, we use a new method to calculate the lower bound of crosstalk. Extensive experimental results show that our algorithm is scalable with problem size. Furthermore, compared to the solution based on an Elmore delay model, our solution reduces the total routing area by up to 30%, the delay to the critical sinks by up to 25%, while further improving crosstalk up to 25.73% on average.
文摘Controlling soil erosion and the transport and deposition of suspended sediment to receiving waters, especially in relation to the modifying influences of, and interplay between, climate and land-use alterations, is essential for effective watershed management. The Atlantic Canada—New England region is expected to experience elevated rainfall erosivity due to climate change over the next century. Using the projected higher precipitation amounts of 5% and 10% for future scenarios of 5 and 25 years for the region, and a spatially-explicit, integrated (GIS, RUSLE) model for a rural watershed in Nova Scotia, predicted increases in total erosion rates of 4.9 and 9.9%, respectively. Modelled scenarios altering buffer strips based on either consistent or slope-variable widths between 30 m (the legal requirement) to 90 m were found to correspond to reductions in predicted total watershed erosion rates from 11% to 32%. Assuming and extending the 1:1 concordance between projected precipitation and estimated soil erosion for this particular watershed into the more distant future of 26 to 55 years, suggests that the 25% increase in soil erosion predicted over this period would have to be offset by expanding the protective buffer strips to a consistent width of 70 m. Adoption of such a protective management scheme would subsume 19% of the terrestrial area of the study watershed and thus consequent reductions in land available for agricultural production and timber harvest.
基金Supported by the Electronics Developing FundProject ( MII[2002]13)
文摘The paper presents a prototype of virtual decoder of the transport stream＇s system target decoder （T-STD）. By connecting the coding model and decoding model, and feeding the overflow of decoding buffer back to control coding, we have got a self-adaptive coding model, and propose an algorithm of muhiplexing multiple elementary streams to a transport stream based on the principle of virtual buffer controlling strategy. The transport stream （TS） which uses this method passes the test of software unzipping and set top-box （STB） playing, and all of the analyzing parameters which are detected by code analyzer accord with the standard of MPEG-2. Some problems that playing time becomes longer and mul tiple TS streaming can not be fit for all the players are also analyzed.
基金supported by National Natural Science Foundation of China (Grant No.50875101)National Hi-tech Research and Development Program of China (863 Program,Grant No.2007AA04Z186)
文摘As two independent problems,scheduling for parts fabrication line and sequencing for mixed-model assembly line have been addressed respectively by many researchers.However,these two problems should be considered simultaneously to improve the efficiency of the whole fabrication/assembly systems.By far,little research effort is devoted to sequencing problems for mixed-model fabrication/assembly systems.This paper is concerned about the sequencing problems in pull production systems which are composed of one mixed-model assembly line with limited intermediate buffers and two flexible parts fabrication flow lines with identical parallel machines and limited intermediate buffers.Two objectives are considered simultaneously：minimizing the total variation in parts consumption in the assembly line and minimizing the total makespan cost in the fabrication/assembly system.The integrated optimization framework,mathematical models and the method to construct the complete schedules for the fabrication lines according to the production sequences for the first stage in fabrication lines are presented.Since the above problems are non-deterministic polynomial-hard（NP-hard）,a modified multi-objective genetic algorithm is proposed for solving the models,in which a method to generate the production sequences for the fabrication lines from the production sequences for the assembly line and a method to generate the initial population are put forward,new selection,crossover and mutation operators are designed,and Pareto ranking method and sharing function method are employed to evaluate the individuals＇ fitness.The feasibility and efficiency of the multi-objective genetic algorithm is shown by computational comparison with a multi-objective simulated annealing algorithm.The sequencing problems for mixed-model production systems can be solved effectively by the proposed modified multi-objective genetic algorithm.
文摘A better understanding of the mechanisms that control nutrient acquisition in the context of plant and ecosystem responses to climate change is needed. Mechanistic nutrient uptake models provide a means to investigate some of the impacts of temperature change on soil nutrient supply and root uptake kinetics through the simulation of key soil and plant processes. The NST 3.0 model, in combination with literature values on plant and soil parameters from a red spruce (Picea rubens L.) site in the southern Appalachians, was used to conduct a series of model simulations focused on the combined effects of changes to the maximal rate of nutrient influx at high concentrations (Imax), root growth rate (k), concentration of nutrient occurring in the soil solution (Cli), and the ability of the soil solid phase to buffer changes to the soil solution nutrient concentration (b). Previous research has indicated that these four parameters are responsive to changes in root zone temperature. Simulated uptake of NH4 increased by a factor of up to 2.6 in response to increases in soil temperature of 1°C to 5°C. The model also projected an increase in P uptake coupled with up to an 80% reduction in solution P concentration in response to a 1°C -5°C increase over a 147-d simulation period. These hypothetical changes, if validated, have interesting implications for plant growth and competition and point to a need for additional studies to better define the impacts of soil temperature on soil nutrient supply and root uptake.
文摘The formation of calcium phosphate phases is extremely important in a biomedical engineering context. These phosphates are used in many applications, such as grafts, drug-delivery processes and evaluation of the bioactivity of metallic surfaces. Considering this scenario, it is useful to evaluate the thermodynamic conditions for the precipitation of phosphates of biomedical interest, mainly hydroxyapatite. In this work, we investigate the effects of two important factors using a thermodynamic framework: 1) carbon dioxide partial pressure;and 2) buffer type (2-Amino-2-hydroxy- methyl-propane-1,3-diol, known as TRIS and 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid, also called HEPES), on the driving force behind the precipitation of calcium phosphates in simulated body fluids. The in silico results show that the pH value is governed by carbon dioxide content, as expected to occur in vivo. Moreover, the buffers can deplete the free calcium available in solution and, consequently, can cause difficulties in the calcium phosphate precipitation.
文摘In Italy high-quality vines are grown on sloping fields where pesticide runoff to surface water is possible and vegetated buffers are suggested as mitigation measure. Spinosad is an insecticide used to control pests in vineyards. For regulatory purposes, FOCUS modelling is used to calculate pesticides runoff reduction provided by a vegetated buffer, but there is an urgent need for field-based results. A field trial with artificial runoff was performed in September 2017 in Northern Italy to evaluate the efficiency of a grassed buffer to reduce spinosad runoff. Trial conditions were based on FOCUS scenarios but made worse to draw prudent conclusions. For the first time in Italy, the trial was conducted according to Good Laboratory Practices to increase reliability of results and reproducibility of the study for regulatory purposes. Five plots were tested, each simulating a grassed buffer of 12 m length on a slope of 10% - 13%. The artificial runoff was 200 mm in 3 hours and rainfall pre- and during runoff was 45 mm. Results show that the 12 m buffer completely retained runoff and effectively mitigated runoff concentration, and mean reduction of spinosad concentration was 59%. A width effect exists, and every 6.5 m of buffer reduces concentration by 50%. Comparison of field results with FOCUS modelling shows that both VFSMod and LM models provide acceptable estimation of runoff reduction for a 5 m buffer, while LM seems more precise. For a 10 m buffer the VFSMod is very accurate, while LM underestimates reduction observed in the field.
基金Supported by China National S&T Major Project(2012ZX03001034MCM 201240113)
文摘The quality of experience（ QoE） evaluation model for voice over IP（ VoI P） service is studied to analyze the impact of network parameters on voice quality and monitor voice quality in real-time for operators.Firstly,the influence of some network parameters on the voice quality of VoI P is investigated. Then,a simulation platform for VoI P transmission is built to collect voice data under different network enviornments. According to the simulation results,a new mapping model between these arguments and VoI P voice quality is deduced. Finally,the accuracy of this voice quality evaluation model is examined and the results demanstrate that it has high reliability and feasibility.
