Different paradigms that relate verification and validation to the simulation model have different development process. A simulation model developing process based on Five-Object Framework (FOF) is discussed in this p...Different paradigms that relate verification and validation to the simulation model have different development process. A simulation model developing process based on Five-Object Framework (FOF) is discussed in this paper. An example is given to demonstrate the applications of the proposed method.展开更多
The content of China＇s economic transformation is not single, and this article argues that it includes three parts. The first is the reform of economic system, the second is the change in the pattern of economic grow...The content of China＇s economic transformation is not single, and this article argues that it includes three parts. The first is the reform of economic system, the second is the change in the pattern of economic growth, and the third is the adjustment of economic structure. Government is the leading force of China＇s economic transformation, and repeated reform of government institutions has brought about some changes to government functions. But problems are obvious that lag changes of government functions have become an obstacle in China＇s economic transformation. This article describes the historical evolution and the reality of China＇s economic transformation, and analyzes the main reasons of lag changes in government functions, and reveals that the transformation of government functions is the key for successful transformation of China＇s economy.展开更多
The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton （CCA）. The calculations are done on various sizes of the simple cubic lattice in the 0 ...The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton （CCA）. The calculations are done on various sizes of the simple cubic lattice in the 0 ≤ D/J ≤ 5 parameter region. The phase diagram of the model and temperature variation of the thermodynamic quantities are obtained. We confirm the existence of a critical end point within the heating calculations. However, in contrast to the heating calculations, we do not obtain the first-order line at low temperature with cooling algorithm calculations. The results are compared with those of other theories.展开更多
ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units ...ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.展开更多
Purpose： Renal denervation （RD） has been demonstrated to be an effective approach to reduce blood pressure for those with resistant hypertension. Yet, we aimed to explore the effect and possible mech- anism of RD o...Purpose： Renal denervation （RD） has been demonstrated to be an effective approach to reduce blood pressure for those with resistant hypertension. Yet, we aimed to explore the effect and possible mech- anism of RD on blood-pressure response to hemorrhagic shock in spontaneously hypertensive rats. Methods： A total of 48 male spontaneously hypertensive rats were randomized to three groups： study group, sham-operation group and control group. RD was achieved by cutting off renal nerves and swabbing phenol on it. Ten weeks after RD, 8 rats in each group were sacrificed to collect the kidney and heart tissues. The remaining rats were subjected to an operation to induce hemorrhagic shock which would lead to 40% loss of total blood volume, and observed for 120 min. The serum concentration of norepinephrine was measured before and three weeks after RD. Results： The blood-pressure and norepinephrine levels were reduced significantly after RD （p 〈 0.05）, Systolic blood pressure and diastolic blood pressure of the surgerygroup were higher than those in the sham and control groups at 15, 30 and 45 min after hemorrhagic shock （p 〈 0.05）, while no significant difference was observed at 60, 90 and 120 min （p 〉 0.05）. Additionally, the beta-1 adrenergic receptor （β1 -AR） in the study group was significantly higher than those in the other two groups （p 〈 0.05） after hemorrhagic shock. Conclusion： This study demonstrated that RD could to some extent improve blood-pressure response to hemorrhagic shock in an established model of severe hemorrhagic shock in spontaneously hypertensive rats. The mechanism might be associated with uo-regulation of β1-AR.展开更多
Superlattices have great application potentials in thermo-electric materials and solid laser techniques.Their complicated heat transport mechanisms due to size effects,multi-interfaces and mini-band are very important...Superlattices have great application potentials in thermo-electric materials and solid laser techniques.Their complicated heat transport mechanisms due to size effects,multi-interfaces and mini-band are very important issues for the prediction of thermal conductivity.In this paper,the short-period Si/Ge superlattices are investigated by a modified series model based on the Debye-Callaway description.The Lambert Law is used to describe the phonon emission within hemisphere space.In addition,the phonon interface transmission coefficients obtained from the phonon wave packet simulation are incorporated into boundary condition of the model,which removes the fitting parameters in the model.Better agreement with experiment is obtained.The effects of temperature,wavelength-dependent phonon transmission,superlattice periods,as well as the thickness of Ge layer are considered in this paper.展开更多
Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a...Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.展开更多
Predicting wind turbine S825 airfoil＇s aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfo...Predicting wind turbine S825 airfoil＇s aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfoil is con- ducted with k-to turbulence model at different attack angles. By comparing with experimental data, a new method of modifying k-to model is proposed. A modifying function is proposed to limit the production term in ω equation based on fluid rotation and deformation. This method improves turbulent viscosity and decreases separating re- gion when the airfoil works at large separating conditions. The predictive accuracy could be improved by using the modified k-to turbulence model.展开更多
The pulse tube refrigerator （PTR） is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretica...The pulse tube refrigerator （PTR） is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretical developments of the pulse tube refrig- erator closely relate with the internal streaming effects. Then the discovering history and classification of the streaming or DC （direct current） flow effect are summarized. It proposes for the first time that the physical significance of the streaming con- tains the driving mechanisms and the transport mechanisms. It demonstrates that the driving mechanisms are the asymmetry of fluid flow and temperature while the transport mechanisms are a loop or vorticity, which transmits nonlinear dissipations. The important advancements have been made over the past two decades all over the world in research of streaming of the pulse tube refrigerator including Gedeon DC flow, Rayleigb streaming, the third type of DC flow and the regenerator circulation. With regard to Gedeon DC flow, theoretical and experimental analyses have been made and different suppression methods are summarized. In the aspect of Rayleigh streaming, it mainly focuses on the analytical solution of the second-order mass flow and the research of tapered pulse tubes. In particular, limited research on the third type of DC flow and regenerator circulation is presented. The experimental measurement techniques of streaming also are summarized. Finally, this paper briefly discusses the key scientific and technical issues of the current research, and foretells the future development trends of streaming research in PTR.展开更多
文摘Different paradigms that relate verification and validation to the simulation model have different development process. A simulation model developing process based on Five-Object Framework (FOF) is discussed in this paper. An example is given to demonstrate the applications of the proposed method.
文摘The content of China＇s economic transformation is not single, and this article argues that it includes three parts. The first is the reform of economic system, the second is the change in the pattern of economic growth, and the third is the adjustment of economic structure. Government is the leading force of China＇s economic transformation, and repeated reform of government institutions has brought about some changes to government functions. But problems are obvious that lag changes of government functions have become an obstacle in China＇s economic transformation. This article describes the historical evolution and the reality of China＇s economic transformation, and analyzes the main reasons of lag changes in government functions, and reveals that the transformation of government functions is the key for successful transformation of China＇s economy.
基金Supported by the Scientific and Technological Research Council of Turkey (TBITAK) under Grant No. 109T018
文摘The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton （CCA）. The calculations are done on various sizes of the simple cubic lattice in the 0 ≤ D/J ≤ 5 parameter region. The phase diagram of the model and temperature variation of the thermodynamic quantities are obtained. We confirm the existence of a critical end point within the heating calculations. However, in contrast to the heating calculations, we do not obtain the first-order line at low temperature with cooling algorithm calculations. The results are compared with those of other theories.
文摘ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.
文摘Purpose： Renal denervation （RD） has been demonstrated to be an effective approach to reduce blood pressure for those with resistant hypertension. Yet, we aimed to explore the effect and possible mech- anism of RD on blood-pressure response to hemorrhagic shock in spontaneously hypertensive rats. Methods： A total of 48 male spontaneously hypertensive rats were randomized to three groups： study group, sham-operation group and control group. RD was achieved by cutting off renal nerves and swabbing phenol on it. Ten weeks after RD, 8 rats in each group were sacrificed to collect the kidney and heart tissues. The remaining rats were subjected to an operation to induce hemorrhagic shock which would lead to 40% loss of total blood volume, and observed for 120 min. The serum concentration of norepinephrine was measured before and three weeks after RD. Results： The blood-pressure and norepinephrine levels were reduced significantly after RD （p 〈 0.05）, Systolic blood pressure and diastolic blood pressure of the surgerygroup were higher than those in the sham and control groups at 15, 30 and 45 min after hemorrhagic shock （p 〈 0.05）, while no significant difference was observed at 60, 90 and 120 min （p 〉 0.05）. Additionally, the beta-1 adrenergic receptor （β1 -AR） in the study group was significantly higher than those in the other two groups （p 〈 0.05） after hemorrhagic shock. Conclusion： This study demonstrated that RD could to some extent improve blood-pressure response to hemorrhagic shock in an established model of severe hemorrhagic shock in spontaneously hypertensive rats. The mechanism might be associated with uo-regulation of β1-AR.
基金supported by the National Basic Research Program of China(Grant No.2012CB933200)the National Natural Science Foundation of China(Grant No.51176091)Science Fund for Creative Research Groups of China(Grant No.51321002)
文摘Superlattices have great application potentials in thermo-electric materials and solid laser techniques.Their complicated heat transport mechanisms due to size effects,multi-interfaces and mini-band are very important issues for the prediction of thermal conductivity.In this paper,the short-period Si/Ge superlattices are investigated by a modified series model based on the Debye-Callaway description.The Lambert Law is used to describe the phonon emission within hemisphere space.In addition,the phonon interface transmission coefficients obtained from the phonon wave packet simulation are incorporated into boundary condition of the model,which removes the fitting parameters in the model.Better agreement with experiment is obtained.The effects of temperature,wavelength-dependent phonon transmission,superlattice periods,as well as the thickness of Ge layer are considered in this paper.
基金Project supported by the National Natural Science Foundation of China （Nos. 41240024, 41372285, 41272317, 51278449, and 51238009）, the Research Fund for the Doctoral Program of Higher Education of China （No. 20110073120012）, and the European Project CREEP （PIAPP-GA-2011-286397）
文摘Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae＊ defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae＊ can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca＊ can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae.
基金supported by the National Natural Science Foundation of China(No.51420105008,No.51376001)the National Basic Research Program of China(2012CB720205,2014CB046405)
文摘Predicting wind turbine S825 airfoil＇s aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfoil is con- ducted with k-to turbulence model at different attack angles. By comparing with experimental data, a new method of modifying k-to model is proposed. A modifying function is proposed to limit the production term in ω equation based on fluid rotation and deformation. This method improves turbulent viscosity and decreases separating re- gion when the airfoil works at large separating conditions. The predictive accuracy could be improved by using the modified k-to turbulence model.
基金supported by the National Natural Science Foundation of China(Grant No.51176198)
文摘The pulse tube refrigerator （PTR） is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretical developments of the pulse tube refrig- erator closely relate with the internal streaming effects. Then the discovering history and classification of the streaming or DC （direct current） flow effect are summarized. It proposes for the first time that the physical significance of the streaming con- tains the driving mechanisms and the transport mechanisms. It demonstrates that the driving mechanisms are the asymmetry of fluid flow and temperature while the transport mechanisms are a loop or vorticity, which transmits nonlinear dissipations. The important advancements have been made over the past two decades all over the world in research of streaming of the pulse tube refrigerator including Gedeon DC flow, Rayleigb streaming, the third type of DC flow and the regenerator circulation. With regard to Gedeon DC flow, theoretical and experimental analyses have been made and different suppression methods are summarized. In the aspect of Rayleigh streaming, it mainly focuses on the analytical solution of the second-order mass flow and the research of tapered pulse tubes. In particular, limited research on the third type of DC flow and regenerator circulation is presented. The experimental measurement techniques of streaming also are summarized. Finally, this paper briefly discusses the key scientific and technical issues of the current research, and foretells the future development trends of streaming research in PTR.
