A mathematical model for simulating concentric-bed and other components of molecular sieve oxygen concentrator is established. In the model, the binary Langmuir equilibrium adsorption equation is adopted to describe t...A mathematical model for simulating concentric-bed and other components of molecular sieve oxygen concentrator is established. In the model, the binary Langmuir equilibrium adsorption equation is adopted to describe the adsorption performance of the adsorbent, the linear driving force (LDF) model is used to describe the mass transfer rate, and the thermal effect during adsorption is considered. The finite difference method is used in simulation and comparison. Numerical results have a reasonable agreement with the experimental research.展开更多
Using a quantum channel consisting of a GHZ state exposed to noisy environment,we investigate how toremotely prepare an entangled state and a qubit state,respectively.By solving the master equation in the Lindbladform...Using a quantum channel consisting of a GHZ state exposed to noisy environment,we investigate how toremotely prepare an entangled state and a qubit state,respectively.By solving the master equation in the Lindbladform,the influence of the various types of noises on the GHZ state is first discussed.Then we use the fidelity to describehow close the remotely prepared state and the initial state are.Our results show that the fidelity is a function of thedecoherence rates and the angles of the initial state.It is found that for each of the two RSP schemes,the influence ofthe noise acting simultaneously in x,y,and z directions on the average fidelity is the strongest while the influence of thenoise acting in x or z direction on the average fidelity is relatively weaker.展开更多
In this paper, the theoretical investigation of remote preparation of an entangledstate is studied in nonideal conditions. Our studies include two parts. In the first part, we consider the remote state preparation (...In this paper, the theoretical investigation of remote preparation of an entangledstate is studied in nonideal conditions. Our studies include two parts. In the first part, we consider the remote state preparation (RSP) of an entangled state through two equally noisy quantum channel states, namely, a mixture of Bell states. Studies show there is a particular mixed-state channel for which all pure entangled states remain entangled after this inexact RSP. In the second part, we suppose that noises which quantum channels suffer from can be expressed as the Lindblad operators. The master equation of the system can be expressed in the Lindblad form. Through solving the master equation, we calculate the fidelity as a function of decoherence rates and parameters of the state to be prepared. For a given entangled state, we investigate the influence of different types of noises on the fidelity.展开更多
Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electromagnetism parts,and it i...Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electromagnetism parts,and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations,a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation,which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta's method,and discrete solutions of all variables are obtained.Finally,by using Matlab language,the system is simulated.The results show that the proposed method works very well.展开更多
This paper introduces the basic viewpoints and characteristics of Bayesian statistics. Which provides a theoretical basis for solving the problem of small sample of flight simulator using Bayesian method. A series of ...This paper introduces the basic viewpoints and characteristics of Bayesian statistics. Which provides a theoretical basis for solving the problem of small sample of flight simulator using Bayesian method. A series of formulas were derived to establish the Bayesian reliability modeling and evaluation model for flight simulation equipment. The two key problems of Bayesian method were pointed out as follows: obtaining the prior distribution of WeibuU parameter, calculating the parameter a posterior distribution and parameter estimation without analytic solution, and proposing the corresponding solution scheme.展开更多
The article reviews a brief literature on the modeling of hydrogen storage device for fuel cell. Different dimensional approaches in modeling hydrogen absorption/desorption in a metal hydride reactor for use in fuel c...The article reviews a brief literature on the modeling of hydrogen storage device for fuel cell. Different dimensional approaches in modeling hydrogen absorption/desorption in a metal hydride reactor for use in fuel cell are summarized. Mathematical modeling equations involved are also stated. The effect of various operating parameters such as temperature, concentration, viscosity, thermal conductivity and time on the gas is also verified. The importance of various simulation software with reference to their major functions is also identified. The review concludes on the opportunities and challenges with the use of hydrogen as an alternative renewable energy.展开更多
By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of r...By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of rubber spring supporting equipment's dynamic performance was discussed first, which is under the condition of existing spring stiffness difference and exciting force bias. Also, the quantitative calculation formulas were given. The results indicate that the performance of vibrating screen is closely related with rubber spring supporting equipment's dynamic performance. Differences of springs' stiffness coefficients reduce the modal frequency reduced, decrease the dynamic stiffness, and increase vibration displacement. Exciting force bias induces a larger lateral displacement. When rubber springs' stiffness coefficients exist, differences and lateral force accounts for 5% in total exciting force; rubber spring supporting equipment's side swing is larger than 1 mm, exceeding the side swing limit.展开更多
A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum (-0.2 nPa) in the ioni...A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum (-0.2 nPa) in the ionization region is obtained by using multiple ultrahigh vacuum pumps. Compared with similar instruments built previously by others~ the H2, CH4 background in the ionization region can be reduced by about two orders of magnitude, and other residual gases in the ionization region can be reduced by about an order of magnitude. Therefore, the signal-to-noise ratio for the temperature programmed desorption (TPD) and time of flight (TOF) spectra is substantially enhanced, making experimental studies of pho- tocatalytic processes on surfaces much easier. In this work, we describe the new apparatus in detail and present some preliminary studies on the photo-induced oxygen vacancy defects on TiO2(110) at 266 nm by using the TPD and TOF methods. Preliminary results suggest that the apparatus is a powerful tool for studying kinetics and mechanism of photochemical processes.展开更多
The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. ...The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. An optimization target for the plan and indexes for assessment were established. Based on the above work, a simulation model was proposed with two layers: a base and a workshop. Dispatching rules were then formulated for the simulation. Experimental results proved the validity of the model and the dispatching algorithm. It was found that the model can solve the capacity evaluation problem for maintenance systems and provides a scientific basis for decision-maker to make decisions regarding equipment maintenance.展开更多
OOS (out-of-step) condition prevention becomes an imperative task to avoid possible power system blackout and collapses. To be confident in correct OOS relaying, the OOS protection device behavior under the vast maj...OOS (out-of-step) condition prevention becomes an imperative task to avoid possible power system blackout and collapses. To be confident in correct OOS relaying, the OOS protection device behavior under the vast majority of power system abnormal regimes should be tested. Comprehensive testing procedure becomes especially important for complex power systems when power system parameters and consequently device settings are not clearly defined or may vary in time. For such complex systems the real OOS protection device testing may become a problem because of specific waveforms of signals persisting during OOS condition. The goal of the methodology, presented in the paper, is to achieve the possibility of out-of-step protection device testing under close-to-real power system operation conditions. The power system stability modelling software is used as a source of test signals. The accurate model of power system in conjunction with dynamical modelling features allows to verify the reliability of OOS protection scheme under consideration as also allows the device settings correction, if necessary. The methodology allows to test the real device with signals waveforms which are hardly obtainable using traditional testing technique.展开更多
Energy is essential for every human activity for more comfortable life but also consumes more natural resources. In order to control human comfort, temperature usually required when the differences in temperature swin...Energy is essential for every human activity for more comfortable life but also consumes more natural resources. In order to control human comfort, temperature usually required when the differences in temperature swing between indoor and outdoor temperatures. PCMs (phase change materials) are the high latent heat materials which can be used in building materials for energy conservation purpose. PCMs can store thermal energy and also can prevent heat to pass through temperature control areas. Paraffin has been used as PCMs are absorbed into the pore of fly ash as paraffin/fly-ash composite and mixed into the buildings materials. Paraffin is an organic material with high melting point (-59℃), and nonflammable materials therefore paraffin can be used as the building materials for the function of PCMs for energy saving purposes. Composite PCMs can be prepared by vacuum impregnation process. Paraffin in liquid form will be impregnated into the pore of fly ash by vacuum capillary force to form paraffin/fly ash composite PCMs. Vacuum impregnation pressures, vacuum times, impregnation times of liquid paraffin in fly ash pores and temperatures for melting the solid paraffin into the liquid form are all affect on the thermal properties of paraffin/fly ash composite PCMs. Paraffin or PCMs impregnation are also relate to the physical property including the fractal dimensions of the pores of the fly ash particles and paraffin/fly ash composite PCMs. The fractal dimensions of the pore of fly ash and paraffin/fiy ash composites PCMs are between the values of 1.0 and 2.0. Fractal dimensions of paraffin/fly-ash composite PCMs have the same trend as the thermal properties for heat capacity and latent heat of melting. These fractal dimensions technique is a novel method to measure physical property of building material related to latent heat and heat capacity.展开更多
Energy is essential for every human activity for more comfortable life, but it also consumes more natural resources. Fossil fuel is the major energy source for energy consumption, and it also emits a lot of air pollut...Energy is essential for every human activity for more comfortable life, but it also consumes more natural resources. Fossil fuel is the major energy source for energy consumption, and it also emits a lot of air pollution during usage to atmosphere and not reproductively. Electrical energy is the secondary energy sources from fossil fuel which is used to operate air conditioning system. In order to control human comfort temperature, it is usually required when the temperature differences swing between indoor and outdoor temperatures. PCMs (phase change materials) are the high latent heat materials which can be used in building materials for energy conservation purpose. PCMs can store thermal energy and prevent heat to pass through temperature control areas. Paraffin has been used as PCMs which is absorbed into the pore of fly ash as paraffin/fly-ash composite and mixed into the buildings materials. Paraffin is an organic material with high melting point (-59 ~C) and nonflammable material, therefore, it can be used as the building materials for the function of PCMs for energy saving purposes. Composite PCMs can be prepared by vacuum impregnation process. Paraffin in liquid form will be impregnated into the pore of fly ash by vacuum capillary force to form paraffin/fly ash composite PCMs. Vacuum impregnation pressures, vacuum times, impregnation times of liquid paraffin in fly ash pores and temperatures for melting the solid paraffin into the liquid form are all affect on the thermal properties of paraffin/fly ash composite PCMs. Composite PCMs will be selected by the optimum thermal properties with optimum of the production conditions for replace the cement powder in the mortar plate compositions. Cement mortar plate with and without composite PCMs will be tested for the thermal insulation properties by comparison as the real day and night time for 8 h period from spot light turn on and off. Temperature detection on the surface and inside the model building under mortar plate with and without composite PCMs is detected every 1 min. Temperature differences between surface of mortar plate over the model building and inside temperature of model building under mortar plates increase with more composite PCMs contents in mortar plates. Thermal insulation efficiency in the building can be enhanced by the composite PCMs utilization as the composition of the building materials.展开更多
The power conversion efficiency of organometallic perovskite-based solar cells has skyrocketed in recent years. Intensive efforts have been made to prepare high-quality perovskite films tailored to various device conf...The power conversion efficiency of organometallic perovskite-based solar cells has skyrocketed in recent years. Intensive efforts have been made to prepare high-quality perovskite films tailored to various device configurations. Planar heterojunction devices have achieved record efficiencies; however, the preparation of perovskite films for planar junction devices requires the use of expensive vacuum facilities and/or the fine control of experimental conditions. Here, we demonstrate a facile preparation of perovskite films using solid-state chemistry. Solid-state precursor thin films of CHBNH3I and PbI2 are brought into contact with each other and allowed to react via thermally accelerated diffusion. The resulting perovskite film displays good optical absorption and a smooth morphology. Solar cells based on these films show an average efficiency of 8.7% and a maximum efficiency of 10%. The solid-state synthesis of organometallic perovskite can also be carried out on flexible plastic substrates. Using this method on a PET/ITO substrate produces devices with an efficiency of 3.2%. Unlike existing synthetic methods for organometallic perovskite films, the solid-state reaction method does not require the use of orthogonal solvents or careful adjustment of reaction conditions, and thus shows good potential for mass production in the future.展开更多
We use decomposition and regression to examine the reasons for the changes in nominal and real rates of return of China's foreign exchange reserves between 2002 and 2009. The results show that the US financial market...We use decomposition and regression to examine the reasons for the changes in nominal and real rates of return of China's foreign exchange reserves between 2002 and 2009. The results show that the US financial market risk premium is the most important determinant of changes in the nominal rate of return, while the US dollar exchange rate and the bulk commodity price are the two key determinants of changes in the real rate of return. From empirically based research, one may conclude that the loose monetary policy of the US Federal Reserve increases China's foreign exchange reserves' nominal rate of return but decreases the real rate of return and that the European debt crisis has an uncertain impact on China's foreign exchange reserves' nominal rate of return but may well raise the real rate of return.展开更多
A scheme is proposed for generating a multiphoton entangled cluster state among four modes. The scheme only uses Kerr medium, beam splitter and homodyne measurements on coherent light fields, which can be efficiently ...A scheme is proposed for generating a multiphoton entangled cluster state among four modes. The scheme only uses Kerr medium, beam splitter and homodyne measurements on coherent light fields, which can be efficiently made in quantum optical laboratories. The photon in the signal mode is prepared in a superposition state of the vacuum state and one-photon state while the probe beam is initially set in a coherent state superposition. The strong probe mode interacts successively with multiple signal-mode photons, each causing a conditional phase rotation in the probe mode. Subsequent momentum quadrature homodyne measurement of the probe mode will project the photons in the signal mode into the desired entangled states. It is shown that under certain conditions, the four-photon cluster state can be generated with high fidelity and high success probability, and the scheme is feasible by current experimental technology.展开更多
A method for system-level simulation between microbolometer designing and Read-Out Integrated Circuit(ROIC) was studied. Three-dimensional(3D) structure modeling of the microbolometer was built. Thermal capacity, ther...A method for system-level simulation between microbolometer designing and Read-Out Integrated Circuit(ROIC) was studied. Three-dimensional(3D) structure modeling of the microbolometer was built. Thermal capacity, thermal conductivity and resistance of the model were obtained from thermoelectric coupling Finite Element Method(FEM) based on the model. An electrical equipment circuit of microbolometer which contains these three parameters was established. By using Verilog-AMS language, the electrical equipment circuit was described as a reduced-order macro-model. Then, the reduced-order macromodel was compiled in cadence to form IP unit of microbolometer, which could be used and identified in cadence. Systemlevel simulation between microbolometer and ROIC was accomplished. Key performances of the device, including input and output characteristics, were obtained in simulation and verified by experimental results.展开更多
The great success of the Sojourner rover in the Mars Pathfinder mission set off a global upsurge of planetary exploration with autonomous wheeled mobile robots(WMRs),or rovers.Planetary WMRs are among the most intelli...The great success of the Sojourner rover in the Mars Pathfinder mission set off a global upsurge of planetary exploration with autonomous wheeled mobile robots(WMRs),or rovers.Planetary WMRs are among the most intelligent space systems that combine robotic intelligence(robint),virtual intelligence(virtint),and human intelligence(humint) synergetically.This article extends the architecture of the three-layer intelligence stemming from successful Mars rovers and related technologies in order to support the R&D of future tele-operated robotic systems.Double-layer human-machine interfaces are suggested to support the integration of humint from scientists and engineers through supervisory(Mars rovers) or three-dimensional(3D) predictive direct tele-operation(lunar rovers).The concept of multilevel autonomy to realize robint,in particular,the Coupled-Layer Architecture for Robotic Autonomy developed for Mars rovers,is introduced.The challenging issues of intelligent perception(proprioception and exteroception),navigation,and motion control of rovers are discussed,where the terrains' mechanical properties and wheel-terrain interaction mechanics are considered to be key.Double-level virtual simulation architecture to realize virtint is proposed.Key technologies of virtint are summarized:virtual planetary terrain modeling,virtual intelligent rover,and wheel-terrain interaction mechanics.This generalized three-layer intelligence framework is also applicable to other systems that require human intervention,such as space robotic arms,robonauts,unmanned deep-sea vehicles,and rescue robots,particularly when there is considerable time delay.展开更多
文摘A mathematical model for simulating concentric-bed and other components of molecular sieve oxygen concentrator is established. In the model, the binary Langmuir equilibrium adsorption equation is adopted to describe the adsorption performance of the adsorbent, the linear driving force (LDF) model is used to describe the mass transfer rate, and the thermal effect during adsorption is considered. The finite difference method is used in simulation and comparison. Numerical results have a reasonable agreement with the experimental research.
基金National Natural Science Foundation of China under Grant Nos.60708003,60578050,and 10434060the State Key Basic Research Program of China under Grant No.2006CB921604+1 种基金the Shanghai Science and Technology Committee under Grant No.07JC14017the Director Fund of State Key Laboratory of Precision Spectroscopy
文摘Using a quantum channel consisting of a GHZ state exposed to noisy environment,we investigate how toremotely prepare an entangled state and a qubit state,respectively.By solving the master equation in the Lindbladform,the influence of the various types of noises on the GHZ state is first discussed.Then we use the fidelity to describehow close the remotely prepared state and the initial state are.Our results show that the fidelity is a function of thedecoherence rates and the angles of the initial state.It is found that for each of the two RSP schemes,the influence ofthe noise acting simultaneously in x,y,and z directions on the average fidelity is the strongest while the influence of thenoise acting in x or z direction on the average fidelity is relatively weaker.
基金The project partially supported by National Natural Science Foundation of China under Grant Nos. 90103026 and 60478029 . We would like to acknowledge useful discussions with Prof. Wu Ying.
文摘In this paper, the theoretical investigation of remote preparation of an entangledstate is studied in nonideal conditions. Our studies include two parts. In the first part, we consider the remote state preparation (RSP) of an entangled state through two equally noisy quantum channel states, namely, a mixture of Bell states. Studies show there is a particular mixed-state channel for which all pure entangled states remain entangled after this inexact RSP. In the second part, we suppose that noises which quantum channels suffer from can be expressed as the Lindblad operators. The master equation of the system can be expressed in the Lindblad form. Through solving the master equation, we calculate the fidelity as a function of decoherence rates and parameters of the state to be prepared. For a given entangled state, we investigate the influence of different types of noises on the fidelity.
基金Supported by the National Science and Technology Support Program(No.2011BAG03B03)Inner Mongolia University of Technology Science and Research Projects of China(No.X201338)
文摘Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electromagnetism parts,and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations,a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation,which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta's method,and discrete solutions of all variables are obtained.Finally,by using Matlab language,the system is simulated.The results show that the proposed method works very well.
文摘This paper introduces the basic viewpoints and characteristics of Bayesian statistics. Which provides a theoretical basis for solving the problem of small sample of flight simulator using Bayesian method. A series of formulas were derived to establish the Bayesian reliability modeling and evaluation model for flight simulation equipment. The two key problems of Bayesian method were pointed out as follows: obtaining the prior distribution of WeibuU parameter, calculating the parameter a posterior distribution and parameter estimation without analytic solution, and proposing the corresponding solution scheme.
文摘The article reviews a brief literature on the modeling of hydrogen storage device for fuel cell. Different dimensional approaches in modeling hydrogen absorption/desorption in a metal hydride reactor for use in fuel cell are summarized. Mathematical modeling equations involved are also stated. The effect of various operating parameters such as temperature, concentration, viscosity, thermal conductivity and time on the gas is also verified. The importance of various simulation software with reference to their major functions is also identified. The review concludes on the opportunities and challenges with the use of hydrogen as an alternative renewable energy.
文摘By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of rubber spring supporting equipment's dynamic performance was discussed first, which is under the condition of existing spring stiffness difference and exciting force bias. Also, the quantitative calculation formulas were given. The results indicate that the performance of vibrating screen is closely related with rubber spring supporting equipment's dynamic performance. Differences of springs' stiffness coefficients reduce the modal frequency reduced, decrease the dynamic stiffness, and increase vibration displacement. Exciting force bias induces a larger lateral displacement. When rubber springs' stiffness coefficients exist, differences and lateral force accounts for 5% in total exciting force; rubber spring supporting equipment's side swing is larger than 1 mm, exceeding the side swing limit.
文摘A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum (-0.2 nPa) in the ionization region is obtained by using multiple ultrahigh vacuum pumps. Compared with similar instruments built previously by others~ the H2, CH4 background in the ionization region can be reduced by about two orders of magnitude, and other residual gases in the ionization region can be reduced by about an order of magnitude. Therefore, the signal-to-noise ratio for the temperature programmed desorption (TPD) and time of flight (TOF) spectra is substantially enhanced, making experimental studies of pho- tocatalytic processes on surfaces much easier. In this work, we describe the new apparatus in detail and present some preliminary studies on the photo-induced oxygen vacancy defects on TiO2(110) at 266 nm by using the TPD and TOF methods. Preliminary results suggest that the apparatus is a powerful tool for studying kinetics and mechanism of photochemical processes.
基金Supported by the National Natural Science Foundation of China under Grant No.60774036
文摘The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. An optimization target for the plan and indexes for assessment were established. Based on the above work, a simulation model was proposed with two layers: a base and a workshop. Dispatching rules were then formulated for the simulation. Experimental results proved the validity of the model and the dispatching algorithm. It was found that the model can solve the capacity evaluation problem for maintenance systems and provides a scientific basis for decision-maker to make decisions regarding equipment maintenance.
文摘OOS (out-of-step) condition prevention becomes an imperative task to avoid possible power system blackout and collapses. To be confident in correct OOS relaying, the OOS protection device behavior under the vast majority of power system abnormal regimes should be tested. Comprehensive testing procedure becomes especially important for complex power systems when power system parameters and consequently device settings are not clearly defined or may vary in time. For such complex systems the real OOS protection device testing may become a problem because of specific waveforms of signals persisting during OOS condition. The goal of the methodology, presented in the paper, is to achieve the possibility of out-of-step protection device testing under close-to-real power system operation conditions. The power system stability modelling software is used as a source of test signals. The accurate model of power system in conjunction with dynamical modelling features allows to verify the reliability of OOS protection scheme under consideration as also allows the device settings correction, if necessary. The methodology allows to test the real device with signals waveforms which are hardly obtainable using traditional testing technique.
文摘Energy is essential for every human activity for more comfortable life but also consumes more natural resources. In order to control human comfort, temperature usually required when the differences in temperature swing between indoor and outdoor temperatures. PCMs (phase change materials) are the high latent heat materials which can be used in building materials for energy conservation purpose. PCMs can store thermal energy and also can prevent heat to pass through temperature control areas. Paraffin has been used as PCMs are absorbed into the pore of fly ash as paraffin/fly-ash composite and mixed into the buildings materials. Paraffin is an organic material with high melting point (-59℃), and nonflammable materials therefore paraffin can be used as the building materials for the function of PCMs for energy saving purposes. Composite PCMs can be prepared by vacuum impregnation process. Paraffin in liquid form will be impregnated into the pore of fly ash by vacuum capillary force to form paraffin/fly ash composite PCMs. Vacuum impregnation pressures, vacuum times, impregnation times of liquid paraffin in fly ash pores and temperatures for melting the solid paraffin into the liquid form are all affect on the thermal properties of paraffin/fly ash composite PCMs. Paraffin or PCMs impregnation are also relate to the physical property including the fractal dimensions of the pores of the fly ash particles and paraffin/fly ash composite PCMs. The fractal dimensions of the pore of fly ash and paraffin/fiy ash composites PCMs are between the values of 1.0 and 2.0. Fractal dimensions of paraffin/fly-ash composite PCMs have the same trend as the thermal properties for heat capacity and latent heat of melting. These fractal dimensions technique is a novel method to measure physical property of building material related to latent heat and heat capacity.
文摘Energy is essential for every human activity for more comfortable life, but it also consumes more natural resources. Fossil fuel is the major energy source for energy consumption, and it also emits a lot of air pollution during usage to atmosphere and not reproductively. Electrical energy is the secondary energy sources from fossil fuel which is used to operate air conditioning system. In order to control human comfort temperature, it is usually required when the temperature differences swing between indoor and outdoor temperatures. PCMs (phase change materials) are the high latent heat materials which can be used in building materials for energy conservation purpose. PCMs can store thermal energy and prevent heat to pass through temperature control areas. Paraffin has been used as PCMs which is absorbed into the pore of fly ash as paraffin/fly-ash composite and mixed into the buildings materials. Paraffin is an organic material with high melting point (-59 ~C) and nonflammable material, therefore, it can be used as the building materials for the function of PCMs for energy saving purposes. Composite PCMs can be prepared by vacuum impregnation process. Paraffin in liquid form will be impregnated into the pore of fly ash by vacuum capillary force to form paraffin/fly ash composite PCMs. Vacuum impregnation pressures, vacuum times, impregnation times of liquid paraffin in fly ash pores and temperatures for melting the solid paraffin into the liquid form are all affect on the thermal properties of paraffin/fly ash composite PCMs. Composite PCMs will be selected by the optimum thermal properties with optimum of the production conditions for replace the cement powder in the mortar plate compositions. Cement mortar plate with and without composite PCMs will be tested for the thermal insulation properties by comparison as the real day and night time for 8 h period from spot light turn on and off. Temperature detection on the surface and inside the model building under mortar plate with and without composite PCMs is detected every 1 min. Temperature differences between surface of mortar plate over the model building and inside temperature of model building under mortar plates increase with more composite PCMs contents in mortar plates. Thermal insulation efficiency in the building can be enhanced by the composite PCMs utilization as the composition of the building materials.
文摘The power conversion efficiency of organometallic perovskite-based solar cells has skyrocketed in recent years. Intensive efforts have been made to prepare high-quality perovskite films tailored to various device configurations. Planar heterojunction devices have achieved record efficiencies; however, the preparation of perovskite films for planar junction devices requires the use of expensive vacuum facilities and/or the fine control of experimental conditions. Here, we demonstrate a facile preparation of perovskite films using solid-state chemistry. Solid-state precursor thin films of CHBNH3I and PbI2 are brought into contact with each other and allowed to react via thermally accelerated diffusion. The resulting perovskite film displays good optical absorption and a smooth morphology. Solar cells based on these films show an average efficiency of 8.7% and a maximum efficiency of 10%. The solid-state synthesis of organometallic perovskite can also be carried out on flexible plastic substrates. Using this method on a PET/ITO substrate produces devices with an efficiency of 3.2%. Unlike existing synthetic methods for organometallic perovskite films, the solid-state reaction method does not require the use of orthogonal solvents or careful adjustment of reaction conditions, and thus shows good potential for mass production in the future.
基金part of the key program of the 2011"Strategic Studies on the Diversification of China’s Foreign Exchange Reserves"of the Chinese Academy of Social SciencesCentral Foreign Exchange Business Center for its support
文摘We use decomposition and regression to examine the reasons for the changes in nominal and real rates of return of China's foreign exchange reserves between 2002 and 2009. The results show that the US financial market risk premium is the most important determinant of changes in the nominal rate of return, while the US dollar exchange rate and the bulk commodity price are the two key determinants of changes in the real rate of return. From empirically based research, one may conclude that the loose monetary policy of the US Federal Reserve increases China's foreign exchange reserves' nominal rate of return but decreases the real rate of return and that the European debt crisis has an uncertain impact on China's foreign exchange reserves' nominal rate of return but may well raise the real rate of return.
基金supported by the National Natural Science Foundation of China (Grant No. 11074002)the Doctoral Foundation of the Ministry of Education of China (Grant No. 20103401110003)the Personal Development Foundation of Anhui Province (Grant No. 2008Z018)
文摘A scheme is proposed for generating a multiphoton entangled cluster state among four modes. The scheme only uses Kerr medium, beam splitter and homodyne measurements on coherent light fields, which can be efficiently made in quantum optical laboratories. The photon in the signal mode is prepared in a superposition state of the vacuum state and one-photon state while the probe beam is initially set in a coherent state superposition. The strong probe mode interacts successively with multiple signal-mode photons, each causing a conditional phase rotation in the probe mode. Subsequent momentum quadrature homodyne measurement of the probe mode will project the photons in the signal mode into the desired entangled states. It is shown that under certain conditions, the four-photon cluster state can be generated with high fidelity and high success probability, and the scheme is feasible by current experimental technology.
基金supported by the National Natural Science Foundation of China(Grant Nos.61235006 and 61421002)
文摘A method for system-level simulation between microbolometer designing and Read-Out Integrated Circuit(ROIC) was studied. Three-dimensional(3D) structure modeling of the microbolometer was built. Thermal capacity, thermal conductivity and resistance of the model were obtained from thermoelectric coupling Finite Element Method(FEM) based on the model. An electrical equipment circuit of microbolometer which contains these three parameters was established. By using Verilog-AMS language, the electrical equipment circuit was described as a reduced-order macro-model. Then, the reduced-order macromodel was compiled in cadence to form IP unit of microbolometer, which could be used and identified in cadence. Systemlevel simulation between microbolometer and ROIC was accomplished. Key performances of the device, including input and output characteristics, were obtained in simulation and verified by experimental results.
基金supported by the National Natural Science Foundation of China(Grant No.61370033)National Basic Research Program of China(Grant No.2013CB035502)+4 种基金Foundation of Chinese State Key Laboratory of Robotics and Systems(Grant Nos.SKLRS201401A01,SKLRS-2014-MS-06)the Fundamental Research Funds for the Central Universities(Grant No.HIT.BRETIII.201411)Harbin Talent Programme for Distinguished Young Scholars(No.2014RFYXJ001)Postdoctoral Youth Talent Foundation of Heilongjiang Province,China(Grant No.LBH-TZ0403)the"111 Project"(Grant No.B07018)
文摘The great success of the Sojourner rover in the Mars Pathfinder mission set off a global upsurge of planetary exploration with autonomous wheeled mobile robots(WMRs),or rovers.Planetary WMRs are among the most intelligent space systems that combine robotic intelligence(robint),virtual intelligence(virtint),and human intelligence(humint) synergetically.This article extends the architecture of the three-layer intelligence stemming from successful Mars rovers and related technologies in order to support the R&D of future tele-operated robotic systems.Double-layer human-machine interfaces are suggested to support the integration of humint from scientists and engineers through supervisory(Mars rovers) or three-dimensional(3D) predictive direct tele-operation(lunar rovers).The concept of multilevel autonomy to realize robint,in particular,the Coupled-Layer Architecture for Robotic Autonomy developed for Mars rovers,is introduced.The challenging issues of intelligent perception(proprioception and exteroception),navigation,and motion control of rovers are discussed,where the terrains' mechanical properties and wheel-terrain interaction mechanics are considered to be key.Double-level virtual simulation architecture to realize virtint is proposed.Key technologies of virtint are summarized:virtual planetary terrain modeling,virtual intelligent rover,and wheel-terrain interaction mechanics.This generalized three-layer intelligence framework is also applicable to other systems that require human intervention,such as space robotic arms,robonauts,unmanned deep-sea vehicles,and rescue robots,particularly when there is considerable time delay.