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Flow field simulation and establishment for mathematical models of flow area of spool valve with sloping U-shape notch machined by different methods 被引量:10
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作者 王兆强 顾临怡 +2 位作者 冀宏 陈家旺 李林 《Journal of Central South University》 SCIE EI CAS 2014年第1期140-150,共11页
Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape not... Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch (ABU) should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch (PBU) is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character. 展开更多
关键词 spool valve flow field simulation flow area steady state flow force mathematical model sloping U-shape notch
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Risk assessment model of tunnel water inrush based on improved attribute mathematical theory 被引量:12
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作者 YANG Xiao-li ZHANG Sheng 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第2期379-391,共13页
Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel... Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel water inrush was proposed based on improved attribute mathematical theory.The trigonometric functions were adopted to optimize the attribute mathematical theory,avoiding the influence of mutation points and linear variation zones in traditional linear measurement functions on the accuracy of the model.Based on comprehensive analysis of various factors,five parameters were selected as the evaluation indicators for the model,including tunnel head pressure,permeability coefficient of surrounding rock,crushing degree of surrounding rock,relative angle of joint plane and tunnel section size,under the principle of dimension rationality,independence,directness and quantification.The indicator classifications were determined.The links among measured data were analyzed in detail,and the objective weight of each indicator was determined by using similar weight method.Thereby the tunnel water inrush risk assessment model is established and applied in four target segments of two different tunnels in engineering.The evaluation results and the actual excavation data agree well,which indicates that the model is of high credibility and feasibility. 展开更多
关键词 tunnel water inrush risk assessment model attribute mathematical theory nonlinear measurement function similar weight method
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Mathematical analyses of the GPS receiver interference tolerance and mean time to loss lock 被引量:5
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作者 Ehab M.Shaheen Sherif A.Elgamel 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2019年第3期440-449,共10页
In this paper, novel mathematical expressions are derived for the Global Positioning System (GPS) receiver interference tolerance in the presence of different types of interference signals such as: continuous wave int... In this paper, novel mathematical expressions are derived for the Global Positioning System (GPS) receiver interference tolerance in the presence of different types of interference signals such as: continuous wave interference, narrowband interference, partial band interference, broadband interference, match spectrum interference and pulse interference. Also, in this paper the mean time to loss lock is determined in order to analyse the mentioned interferences effect on the GPS receiver. These derived analytical expressions are validated with the aid of extensive simulation experiments. 展开更多
关键词 mathematical ANALYSES GPS RECEIVER INTERFERENCE TOLERANCE
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Mathematical models and expert system for grate-kiln process of iron ore oxide pellet production.Part Ⅱ:Rotary kiln process control 被引量:7
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作者 范晓慧 王祎 陈许玲 《Journal of Central South University》 SCIE EI CAS 2012年第6期1724-1727,共4页
Rotary kiln process for iron ore oxide pellet production is hard to detect and control.Construction of one-dimensional model of temperature field in rotary kiln was described.And the results lay a solid foundation for... Rotary kiln process for iron ore oxide pellet production is hard to detect and control.Construction of one-dimensional model of temperature field in rotary kiln was described.And the results lay a solid foundation for online control.Establishment of kiln process control expert system was presented,with maximum temperature of pellet and gas temperature at the feed end as control cores,and interval estimate as control strategy.Software was developed and put into application in a pellet plant.The results show that control guidance of this system is accurate and effective.After production application for nearly one year,the compressive strength and first grade rate of pellet are increased by 86 N and 2.54%,respectively,while FeO content is 0.05% lowered.This system can reveal detailed information of real time kiln process,and provide a powerful tool for online control of pellet production. 展开更多
关键词 mathematical model expert system one-dimensional temperature field rotary kiln iron ore oxide pellet
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Mathematical models and expert system for grate-kiln process of iron ore oxide pellet production(Part Ⅰ):Mathematical models of grate process 被引量:4
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作者 王祎 范晓慧 陈许玲 《Journal of Central South University》 SCIE EI CAS 2012年第4期1092-1097,共6页
Grate process is an important step in grate-kiln pellet production.However,as a relatively closed system,the process on grate is inaccessible to direct detection,therefore,it is hard to control.As a result,mathematica... Grate process is an important step in grate-kiln pellet production.However,as a relatively closed system,the process on grate is inaccessible to direct detection,therefore,it is hard to control.As a result,mathematical models of temperature distribution,moisture distribution and oxidation degree distribution in pellet bed,with good universality,computation speed and calculation accuracy,are presented based on analysis of heat transfer and physical-chemical reactions during grate process.And real-time visualization of temperature,moisture and oxidation degree distribution in pellet bed during grate process is realized.Model validation is displayed,and the similarity of 91% is proved.The results can reveal real time status on grate,and provide a solid foundation for the subsequent study of artificial intelligence control system of pellet production. 展开更多
关键词 mathematical model temperature distribution moisture distribution oxidation degree distribution iron ore oxide pellet
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A Partial Parallel Airport Gate Assignment Supported by a Knowledge-based System Combined with Mathematical Programming 被引量:2
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作者 Cheng Yu(Center for Transportation Studies, School of Civil and Structural EngineeringNanyang Technological University, Singapore, 2263) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1996年第3期43-61,共19页
The gate assignment at an airport is one of the major activities in airport operations.With the increase of passenger traffic volumes and the number of flights, the complexity of this task and the factors to be consid... The gate assignment at an airport is one of the major activities in airport operations.With the increase of passenger traffic volumes and the number of flights, the complexity of this task and the factors to be considered have increased significantly, and an efficient gate utilizationhas received considerable attention. For overcoming the shortcomings of previous gate assignmentapproaches, this paper presents a partial parallel gate assignment approach, by which more factorsconcerning aircraft and gates can be collsidered at the same time. This paper also presents themethod of using a knowledge-based system combined with a mathematical programming method forgetting an optimized feasible assignment solution. By this way, it is more easily to get the solutionthat satisfies both the static and dynamic situations,and thus it may adapt well to meet the needsof actual use to rea-time operations. An experimental prototype has been implemented, and a casestudy is presented at the end of the paper. 展开更多
关键词 Airport operations Gate assignment Knowledge-based system mathematical programming.
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Mathematical modeling and analytical solution for stretching force of automatic feed mechanism 被引量:1
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作者 魏志芳 陈国光 《Journal of Central South University》 SCIE EI CAS 2008年第S2期389-393,共5页
Load of an automatic feed mechanism is composed of the stretching force of feed belt at the entrance to lower flexible guidance and the friction force between feed belt and flexible guidance. A mathematical model for ... Load of an automatic feed mechanism is composed of the stretching force of feed belt at the entrance to lower flexible guidance and the friction force between feed belt and flexible guidance. A mathematical model for computing the load was presented. An optimization problem was formulated to determine the attitude of the flexible guidance based on the principle that the potential energy stored in the system was the minimum at the equilibrium. Then the friction force was obtained according to the attitude of guide leaves and the moving velocity of the feed belt and the friction factor. Consequently, the load of the automatic feed mechanism can be calculated. Finally, an example was given to compute the load when the horizontal and elevating firing angles of the automation were respectively 45° and 30°. The computing result can be a criterion to determine the designing parameters of automat. 展开更多
关键词 mathematical model load automatic FEED mechanism optimization problem potential energy hoist-feed system
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Building up a Mathematical Model of Shaftes System and CAD for Linked Tetra-Shaft and Double-Cantilever Flat Flap Gate 被引量:1
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作者 FuQ满怀 ZhaoZe-bin 《Journal of Northeast Agricultural University(English Edition)》 CAS 1999年第2期139-146,共8页
Linked tetra shaft and double cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination ... Linked tetra shaft and double cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination of the type of sluice,this paper researches the difficult points of design advance,through researching the motion locus & stress coundition of linked tetra shaft system.The writer will build up the mathmatical model and handle it with the computer.Thus,we can achieve the modern desing on the basis of the software of linked tetra shaft system development. 展开更多
关键词 linked tetra shaft flap gate shaft system mathematical model CAD
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Influence on the Ground and Air and Mathematical Description of the High-Voltage Discharge
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作者 Dvorkin Iouri Oles Savchuk +1 位作者 Inga Voropaeva Alexei Voloboy 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期281-282,共2页
According to trends of the development the high-voltage devices’ usage and unpredictable weather causes,we find it very important to research electrical discharge from different sources.In our opinion,the most import... According to trends of the development the high-voltage devices’ usage and unpredictable weather causes,we find it very important to research electrical discharge from different sources.In our opinion,the most important is to analyze an influence of the atmospheric electricity on the air and ground, create an exact mathematical model of the physical processes,and describe the ecological influence. 展开更多
关键词 DISCHARGE atmospheric ELECTRICITY RUPTURE of the cable noise pollution AIR IONIZATION fulgurites mathematical model
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A Numerical Method for Rigid-plastic FEM Analysis Basing on Mathematical Programming
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作者 Li Di Lin Zhongqin Chen Guanlong Zhang Weigang Li Shuhui 《上海交通大学学报》 EI CAS CSCD 北大核心 2004年第z2期32-37,共6页
The rigid-plastic analysis of mental forming simulation is formulated as a discrete nonlinear mathematical programming problem with equality and inequality constraints by means of the finite element technique. An iter... The rigid-plastic analysis of mental forming simulation is formulated as a discrete nonlinear mathematical programming problem with equality and inequality constraints by means of the finite element technique. An iteration algorithm is used to solve this formulation, which distinguishes the integration points of the rigid zones and the plastic zones and solves a series of the quadratic programming to overcome the difficulties caused by the nonsmoothness and the nonlinearity of the objective function. This method has been used to carry out the rigid-plastic FEM analysis. An example is given to demonstrate the effectiveness of this method. 展开更多
关键词 RIGID-PLASTIC mathematical PROGRAMMING FINITE ELEMENT method
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Determination of Minimum Enzymatic Decolorization Time of Reactive Dye Solution by Spectroscopic & Mathematical Approach
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作者 Mithat Celebi Zafer Omer Ozdemir +2 位作者 Emre Eroglu Melda Altikatoglu Ibrahim Guney 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2015年第2期340-345,共6页
Synthetic dyes are very important for textile dyeing,paper printing,color photography and petroleum products.Traditional methods of dye removal include biodegradation,precipitation,adsorption,chemical degradation,phot... Synthetic dyes are very important for textile dyeing,paper printing,color photography and petroleum products.Traditional methods of dye removal include biodegradation,precipitation,adsorption,chemical degradation,photo degradation,and chemical coagulation.Dye decolorization with enzymatic reaction is an important issue for several research field(chemistry,environment)In this study,minimum decolorization time of Remazol Brilliant Blue R dye with Horseradish peroxidase enzyme was calculated using with mathematical equation depending on experimental data.Dye decolorization was determined by monitoring the absorbance decrease at the specific maximum wavelength for dye.All experiments were carried out with different initial dye concentrations of Remazol Brilliant Blue R at 25 ℃ constant temperature for 30 minutes.The development of the least squares estimators for a nonlinear model brings about complications not encountered in the case of the linear model.Decolorization times for completely removal of dye were calculated according to equation.It was shown that mathematical equation was conformed exponential curve for dye degradation. 展开更多
关键词 DECOLORIZATION Horseradish peroxidase mathematical modeling Reactive dye UV-visible spec-trophotometry
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Mathematical model of deformation resistance of 30 MnSi V steel
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作者 戴铁军 刘战英 +1 位作者 刘相华 王国栋 《中国有色金属学报》 EI CAS CSCD 北大核心 2001年第z1期210-212,共3页
Based on 30MnSiV steel, the deformation resistance was studied by using Gleeble 1500 thermomechanical simulator. The mathematical model of the deformation resistance is established by analyzing the relationship of the... Based on 30MnSiV steel, the deformation resistance was studied by using Gleeble 1500 thermomechanical simulator. The mathematical model of the deformation resistance is established by analyzing the relationship of the deformation temperature, deformation rate and deformation resistance. The regression equation is highly noticeable by means of regression analysis. The mathematical model corresponds to test data by means of the contrast. 展开更多
关键词 thermomechanical simulator mathematical model regression deformation resistance
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Governing Equation and Mathematical Simulation on Ablation and Transpiration Control
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作者 Yang Xueshi and Gao Wei Beijing Institute of Electromechanic System Engineering, P.O. Box 3924, Beijing 100854, ChinaYuan Zhaoding Institute of Computer Application and Simulation Technology, Beijing 100854Xu YanhouDepartment of Modem Mechanics, University of Science and Technology of China, Hefei 230026 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1992年第3期44-58,共15页
This paper represents a physical model of two -dimensional transpiration cooling control system with surface heating and ablating. The governing equation is derived and the third boundary conditions are given. They co... This paper represents a physical model of two -dimensional transpiration cooling control system with surface heating and ablating. The governing equation is derived and the third boundary conditions are given. They constitute a two -dimensional variable -domain distributed parameter control system in which the control parameter appears in both the governing equation and the boundary conditions. Applying time semi-step alternating direction method to difference this mathematical model, the tridiagonal difference equations are obtained. For a flying shell of electromagnetic railgun, the mathematical simulation results agree with the realistic physical process, and the control parameter not only can control the temperature of heat shield, but also can control the boundary motion effectively. 展开更多
关键词 TRANSPIRATION Variable-boundary Heat transfer mathematical simulation.
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中国概率统计学会(CSPS)和Institute of Mathematical Statistics(IMS)2005年举办CSPS/IMS联合会议征文通知
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《应用概率统计》 CSCD 北大核心 2004年第3期333-333,共1页
经CSPS与IMS商定将于2005年在北京联合召开概率统计学术会议.该会议由中国概率统计学会和IMS联合主办,中国现场研究会、中国统计学会和中国统计教育学会协办.现已决定于2005年7月9日-12日(8日报到)在北京大学英杰交流中心举行这次“CSPS... 经CSPS与IMS商定将于2005年在北京联合召开概率统计学术会议.该会议由中国概率统计学会和IMS联合主办,中国现场研究会、中国统计学会和中国统计教育学会协办.现已决定于2005年7月9日-12日(8日报到)在北京大学英杰交流中心举行这次“CSPS/IMS 2005联合会议”.有关会议事宜如下: 1.投稿论文须是2005年7月底以前没有发表的. 展开更多
关键词 概率统计学 会议 CSPS/IMS CSPS Institute of mathematical Statistics
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A Mathematical Model for Juice Extraction from Chopped Sweet Sorghum
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作者 Sun Xiao-zheng Yamana Nobuki 《Journal of Northeast Agricultural University(English Edition)》 CAS 2017年第2期81-88,共8页
Juice extraction from chopped sweet sorghum is an example of flow through porous media. Darcy’s law is often used to express this type of phenomenon. However, using Darcy’s law to construct a mathematical model to p... Juice extraction from chopped sweet sorghum is an example of flow through porous media. Darcy’s law is often used to express this type of phenomenon. However, using Darcy’s law to construct a mathematical model to predict juice extraction from chopped sweet sorghum is difficult, because the volume of the porous media changes during the pressing operations. A mathematical model was developed from fundamental analysis to predict the juice extraction ratio of chopped sweet sorghum, and experiments were conducted to verify the model. An experimental piston-cylinder assembly was developed to conduct the validation experiments. The parameters in the developed model were estimated by using non-linear regression analysis from the experimental data. Plots of the mathematical model agreed well with experimental data. R^2(coefficient of determination) values for all the regressions studied were higher than 0.99. Results showed that the juice extraction ratio of chopped sweet sorghum approached an asymptote with a maximum value that depended on the physical form of the sample. The model could help in understanding the mechanics of juice extraction from chopped sweet sorghum. 展开更多
关键词 juice extraction property mathematical model pressure use efficiency sweet sorghum
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Mathematical Foundation of Visual Query Languageon Spatial Information
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作者 Wang Jianhua Guo Jingjun +2 位作者 Yan Huiwu Zhu Guorui Wu Hehai 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2000年第4期66-72,共7页
Visual Query Language on Spatial Information (SIVQL) is one kind of visual query language based on the extension of Query by Example (QBE). It is a visual operation based on graphics or media object, such as point, li... Visual Query Language on Spatial Information (SIVQL) is one kind of visual query language based on the extension of Query by Example (QBE). It is a visual operation based on graphics or media object, such as point, line and area elements. In this paper, the relation calculation and query function of SIVQL have been studied and discussed by using set theory and relation algebra. The theory foundation of SIVQL has been investigated by the mathematical method. Finally, its application examples are also given with the specific information system. 展开更多
关键词 Visual query language Relation algebra mathematical foundation
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Index Design and Comprehensive Evaluation of Germplasm Resources of Fruits Based on Mathematical Model of AHP and FCE:Sterculia nobilis Smith as a Case
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作者 Li Wen-yan Wei You Zhou Jing 《Journal of Northeast Agricultural University(English Edition)》 CAS 2021年第2期35-44,共10页
The mathematical model of analytic hierarchy process(AHP)-fuzzy comprehensive evaluation(FCE)was applied to comprehensively evaluate the germplasm resources of Sterculia nobilis Smith,and the scientific nature and rel... The mathematical model of analytic hierarchy process(AHP)-fuzzy comprehensive evaluation(FCE)was applied to comprehensively evaluate the germplasm resources of Sterculia nobilis Smith,and the scientific nature and reliability of the mathematical model was verified by calculating index weights and comprehensive evaluation scores.In this paper,11 indicators were selected to construct a comprehensive evaluation system from four dimensions of yields,resistances,contents of main inclusions in seeds and tree shapes.AHP method was applied to calculate the index weight of each dimension,after passing the consistency test,FCE method was applied to comprehensively evaluate germplasm resources of S.nobilis Smith.The index weights of the yields,resistances,contents of major inclusions in seeds and tree shapes were 0.5518,0.2554,0.1279 and 0.0649,respectively.The yield had the greatest influence on the comprehensive evaluation of germplasm resources of S.nobilis Smith,which was in line with the actual production demand of S.nobilis Smith as a food crop.However,resistances and contents of major inclusions in seeds had limited influence on it,while tree shapes had the least influence on it.After fuzzy comprehensive evaluation,the final evaluation score was 88.00,the corresponding evaluation score was between 4 and 5,and the evaluation results ranged from slight good to good,which indicated that the evaluation weights corresponding to the four dimensions were more scientific and reasonable.In this study,the mathematical model of AHP-FCE was used to establish and evaluate the comprehensive evaluation system of the germplasm resources of S.nobilis Smith.According to the values of index weights and the evaluation results,it showed that the mathematical model was scientific and reliable,and it could provide a new reference method for the comprehensive evaluation of germplasm resources of other fruits. 展开更多
关键词 Sterculia nobilis Smith comprehensive evaluation AHP-FCE mathematical model germplasm resource
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Mathematical Simulating Model of Phased-Array Antenna in Multifunction Array Radar
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作者 Wang, Guoyu Zhang, Jun Ma, Jianwu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1999年第1期39-43,共5页
A mathematical simulating model of phased-array antenna in multifunction array radar has been approached in this paper, including the mathematical simulating model of plane phased-array pattern, the mathematical simul... A mathematical simulating model of phased-array antenna in multifunction array radar has been approached in this paper, including the mathematical simulating model of plane phased-array pattern, the mathematical simulating model of directionality factor, the mathematical simulating model of array factor, the mathematical simulating model of array element factor and the mathematical simulating model of beam steering. 展开更多
关键词 Antenna phased arrays Directional patterns (antenna) mathematical models
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The Development and Application of Combined Thermoregulatory Mathematical Models
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作者 Gu Dingliang and Pang ChengInstitute of Space Medico-Engineering, Beijing 100094, China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1991年第2期55-64,共10页
Thermoregulatory mathematical models have being developed for more than half a century and obtained more and more wide application. Among them, the 'engineering-physiological' thermal models, which correlated ... Thermoregulatory mathematical models have being developed for more than half a century and obtained more and more wide application. Among them, the 'engineering-physiological' thermal models, which correlated closely to the man-machine-environment system, are the ones that developed most rapidly and have been widely accepted by thermal physiologists and environmental control engineers.This paper attempts to outline briefly the development and application of such kind of thermal models, discusses how to further develop and apply various combined thermal models in practice, and puts forward four respects of suggestions for establishment and modification of combined thermal models of man-clothing-cabin environment. 展开更多
关键词 Thermoregulatory mathematical model Man-clothing-cabin environment system.
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Mathematical modeling and analysis of thermodynamic processes in a twin-rotor piston engine 被引量:1
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作者 邹腾安 徐海军 +2 位作者 潘存云 徐小军 陈虎 《Journal of Central South University》 SCIE EI CAS 2014年第11期4163-4171,共9页
In order to study the major performance indicators of the twin-rotor piston engine(TRPE), Matlab/simulink was used to simulate the mathematical models of its thermodynamic processes. With consideration of the characte... In order to study the major performance indicators of the twin-rotor piston engine(TRPE), Matlab/simulink was used to simulate the mathematical models of its thermodynamic processes. With consideration of the characteristics of the working processes in the TRPE, corresponding differential equations were established and then simplified by period features of the TRPE. Finally, the major boundary conditions were figured out. The changing trends of mass, pressure and temperature of working fuel in the working chamber during a complete engine cycle were presented. The simulation results are consistent with the trends of an actual working cycle in the TRPE, which indicates that the method of simulation is feasible. As the pressure in the working chamber is calculated, all the performance parameters of the TRPE can be obtained. The major performance indicators, such as the indicated mean effective pressure, power to weight ratio and the volume power, are also acquired. Compared with three different types of conventional engines, the TRPE has a bigger utilization ratio of cylinder volume, a higher power to weight ratio and a more compact structure. This indicates that TRPE is superior to conventional engines. 展开更多
关键词 twin-rotor piston engine mathematic model thermodynamic process simulation utilization ratio of cylinder volume
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