Nowadays,people still rely on traditional heating methods in rural areas of northern China,such as Kang(bed-stoves) and burning caves in cold winter.Field measurements of indoor environment were carried out in several...Nowadays,people still rely on traditional heating methods in rural areas of northern China,such as Kang(bed-stoves) and burning caves in cold winter.Field measurements of indoor environment were carried out in several rural houses with burning-cave-coil-Kang coupling heating system in northern China.The results show that this system is able to realize the graded use of internal energy of burning cave.The temperature of supply pipe water ranged from 30 ℃ to 50 ℃ which met the demands in 74.7% of time.The surface temperature of Kang maintained at above 25 ℃.Compared with traditional burning cave,using burning-cave-coil-Kang coupled with heating system has a higher thermal efficiency of 48.9%,which is 8.32% higher than the traditional one.展开更多
As a further theoretical study of the collision-induced quantum interference on rotational energy transfer in an atom-diatom system, based on the first-Born approximation of time-dependent perturbation theory, taking ...As a further theoretical study of the collision-induced quantum interference on rotational energy transfer in an atom-diatom system, based on the first-Born approximation of time-dependent perturbation theory, taking into account the anisotropic Lennard-Jones interaction potential and the long-range interaction potential, the differential interference angles in singlet-triplet mixed states of CO A^1Π（v=9）-e3∑-（v=1） system in collision with He, Ne, Ar, and other partners were calculated theoretically. The relationships of differential interference angle versus impact parameters, including collision parameter b and velocity, are obtained.展开更多
The main objective of this paper is to show an overview analysis of market power issues.Market power reflects the scarcity of power supply.It is the ability of a particular seller or group of sellers to maintain price...The main objective of this paper is to show an overview analysis of market power issues.Market power reflects the scarcity of power supply.It is the ability of a particular seller or group of sellers to maintain prices profitably above competitive levels for a significant period of time.Because the electric power system has its own characteristics that are different to other economic systems,both physical factors and economic factors of power system are key elements on this definition.We study some cases here,including different line limit levels,load levels and bid strategy through a market model based on OPF (optimal power flow) with a decommitment algorithm.展开更多
The Unified Power Flow Controller （UPFC） is one of the most versatile Flexible AC Transmission Systems （FACTS） devices that has unique capability of independently controlling the real and reactive power flows, in ...The Unified Power Flow Controller （UPFC） is one of the most versatile Flexible AC Transmission Systems （FACTS） devices that has unique capability of independently controlling the real and reactive power flows, in addition to regulate the system bus voltage. This paper presents performance analysis of Unified Power Flow Controller based on two axis theory. Based on this analysis, a new Artificial Neural Network （ANN） based controller has been proposed to improve the system performance. The controller rules are structured depending upon the relationship between series inserted voltage and the desired changes in real/reactive power flow in the power system. The effects of different controllers along with parameters of series transformer and transmission line have been investigated through developed control block model in SIMULINK tool box of MATLAB. The effectiveness of the proposed scheme is demonstrated by case studies.展开更多
This study presents a novel solar concentrating photovoltaic/concentrating solar power （CPV/CSP） hybrid system, which mainly contains CPV modules with an evaporative cooling subsystem, a thermal receiver and an orga...This study presents a novel solar concentrating photovoltaic/concentrating solar power （CPV/CSP） hybrid system, which mainly contains CPV modules with an evaporative cooling subsystem, a thermal receiver and an organic Rankine cycle （ORC）. The cooling fluid is boiled when cooling the CPV modules, and superheated vapor that is effective for power generation with an ORC is generated after absorbing low-concentration solar radiation in the thermal receiver. A steady-state physical model is developed to carry out energy analysis of the hybrid sys- tem. The results show that when saturated vapor is fed into the thermal receiver, the peripheral low-concentration solar radiation that is discarded in conventional CPV or CPV/ thermal systems is effective to get a high-temperature superheated vapor （e.g., above 120 ℃）. The overall solar- to-electricity efficiency can be increased from 28.4 % for the conventional CPV system to 44 % for the hybrid sys- tem with 500 suns. Even though the overall efficiency decreases from 44.0 % to 36.8 % when the concentration ratio increases from 500 to 2,000 suns, there is still a considerable efficiency improvement compared with the conventional CPV systems. The results indicate that the proposed hybrid system provides a viable solution for solar power generation with high efficiencies.展开更多
In target tracking, the measurements collected by sensors can be biased in some real scenarios, e.g., due to systematic error. To accurately estimate the target trajectory, it is essential that the measurement bias be...In target tracking, the measurements collected by sensors can be biased in some real scenarios, e.g., due to systematic error. To accurately estimate the target trajectory, it is essential that the measurement bias be identified in the first place. We investigate the iterative bias estimation process based on the expectation-maximization（EM）algorithm, for cases where sufficiently large numbers of measurements are at hand. With the assistance of extended Kalman filtering and smoothing, we derive two EM estimation processes to estimate the measurement bias which is formulated as a random variable in one state-space model and a constant value in another. More importantly,we theoretically derive the global convergence result of the EM-based measurement bias estimation and reveal the link between the two proposed EM estimation processes in the respective state-space models. It is found that the bias estimate in the second state-space model is more accurate and of less complexity. Furthermore, the EM-based iterative estimation converges faster in the second state-space model than in the first one. As a byproduct, the target trajectory can be simultaneously estimated with the measurement bias, after processing a batch of measurements.These results are confirmed by our simulations.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.51178075)the Fundamental Research Funds for the Central Universities(Grant No.DUT17RW118)
文摘Nowadays,people still rely on traditional heating methods in rural areas of northern China,such as Kang(bed-stoves) and burning caves in cold winter.Field measurements of indoor environment were carried out in several rural houses with burning-cave-coil-Kang coupling heating system in northern China.The results show that this system is able to realize the graded use of internal energy of burning cave.The temperature of supply pipe water ranged from 30 ℃ to 50 ℃ which met the demands in 74.7% of time.The surface temperature of Kang maintained at above 25 ℃.Compared with traditional burning cave,using burning-cave-coil-Kang coupled with heating system has a higher thermal efficiency of 48.9%,which is 8.32% higher than the traditional one.
基金This work was supported by the National Natural Science Foundation of China （No.10374040） and the Educational Department of Liaoning Province （No.20060347）.
文摘As a further theoretical study of the collision-induced quantum interference on rotational energy transfer in an atom-diatom system, based on the first-Born approximation of time-dependent perturbation theory, taking into account the anisotropic Lennard-Jones interaction potential and the long-range interaction potential, the differential interference angles in singlet-triplet mixed states of CO A^1Π（v=9）-e3∑-（v=1） system in collision with He, Ne, Ar, and other partners were calculated theoretically. The relationships of differential interference angle versus impact parameters, including collision parameter b and velocity, are obtained.
基金This paper supported by National Natural Science Foundation of China (50079006).
文摘The main objective of this paper is to show an overview analysis of market power issues.Market power reflects the scarcity of power supply.It is the ability of a particular seller or group of sellers to maintain prices profitably above competitive levels for a significant period of time.Because the electric power system has its own characteristics that are different to other economic systems,both physical factors and economic factors of power system are key elements on this definition.We study some cases here,including different line limit levels,load levels and bid strategy through a market model based on OPF (optimal power flow) with a decommitment algorithm.
文摘The Unified Power Flow Controller （UPFC） is one of the most versatile Flexible AC Transmission Systems （FACTS） devices that has unique capability of independently controlling the real and reactive power flows, in addition to regulate the system bus voltage. This paper presents performance analysis of Unified Power Flow Controller based on two axis theory. Based on this analysis, a new Artificial Neural Network （ANN） based controller has been proposed to improve the system performance. The controller rules are structured depending upon the relationship between series inserted voltage and the desired changes in real/reactive power flow in the power system. The effects of different controllers along with parameters of series transformer and transmission line have been investigated through developed control block model in SIMULINK tool box of MATLAB. The effectiveness of the proposed scheme is demonstrated by case studies.
基金supported by the National Natural Science Foundation of China(51106149 and 51406051)the Fundamental Research Funds for the Central Universitiesthe Foundation of Key Laboratory of Thermo-Fluid Science and Engineering(Xi’an Jiaotong University),Ministry of Education,Xi’an710049,China
文摘This study presents a novel solar concentrating photovoltaic/concentrating solar power （CPV/CSP） hybrid system, which mainly contains CPV modules with an evaporative cooling subsystem, a thermal receiver and an organic Rankine cycle （ORC）. The cooling fluid is boiled when cooling the CPV modules, and superheated vapor that is effective for power generation with an ORC is generated after absorbing low-concentration solar radiation in the thermal receiver. A steady-state physical model is developed to carry out energy analysis of the hybrid sys- tem. The results show that when saturated vapor is fed into the thermal receiver, the peripheral low-concentration solar radiation that is discarded in conventional CPV or CPV/ thermal systems is effective to get a high-temperature superheated vapor （e.g., above 120 ℃）. The overall solar- to-electricity efficiency can be increased from 28.4 % for the conventional CPV system to 44 % for the hybrid sys- tem with 500 suns. Even though the overall efficiency decreases from 44.0 % to 36.8 % when the concentration ratio increases from 500 to 2,000 suns, there is still a considerable efficiency improvement compared with the conventional CPV systems. The results indicate that the proposed hybrid system provides a viable solution for solar power generation with high efficiencies.
基金supported by the National Natural Science Foundation of China(No.61601254)the KC Wong Magna Fund of Ningbo University,China
文摘In target tracking, the measurements collected by sensors can be biased in some real scenarios, e.g., due to systematic error. To accurately estimate the target trajectory, it is essential that the measurement bias be identified in the first place. We investigate the iterative bias estimation process based on the expectation-maximization（EM）algorithm, for cases where sufficiently large numbers of measurements are at hand. With the assistance of extended Kalman filtering and smoothing, we derive two EM estimation processes to estimate the measurement bias which is formulated as a random variable in one state-space model and a constant value in another. More importantly,we theoretically derive the global convergence result of the EM-based measurement bias estimation and reveal the link between the two proposed EM estimation processes in the respective state-space models. It is found that the bias estimate in the second state-space model is more accurate and of less complexity. Furthermore, the EM-based iterative estimation converges faster in the second state-space model than in the first one. As a byproduct, the target trajectory can be simultaneously estimated with the measurement bias, after processing a batch of measurements.These results are confirmed by our simulations.
