We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerat...We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerated and degenerated. By applying the hard-wall boundary condition of the semi-infinite waveguide, it is found that singlephoton polarization conversion can be realized with unit probability for both cases under the ideal condition.Together with the polarization conversion, the frequency conversion of a single photon can also be realized with unit probability in the ideal case if the Λ system is not degenerated.展开更多
In this paper,battery aging diversity among independent cells was studied in terms of available capacity degradation.During the aging process of LiFePO_(4)batteries,the phenomenon of aging diversity can be observed.Wh...In this paper,battery aging diversity among independent cells was studied in terms of available capacity degradation.During the aging process of LiFePO_(4)batteries,the phenomenon of aging diversity can be observed.When batteries with same specification were charged and discharged repeatedly under the same working conditions,the available capacity of different cell decreased at different rates along the cycle number.In this study,accelerated aging tests were carried out on multiple new LiFePO_(4)battery samples of different brands.Experimental results show that under the same working conditions,the actual available capacity of all cells decreased as the number of aging cycle increased,but an obvious aging diversity was observed even among different cells of same brand with same specification.This aging diversity was described and analysed in detail,and the common aging features of different cells beneath this aging diversity was explored.Considering this aging diversity,a probability density concept was adopted to estimate battery’s state of health(SOH).With this method,a relationship between battery SOH and its aging feature parameter was established,and a dynamic sliding window optimization technique was designed to ensure the optimal quality of aging feature extraction.Finally,the accuracy of this SOH estimation method was verified by random test.展开更多
This paper presents a new inverter based on three-phase Boost/Buck-boost single-stage inverter. The basic configuration of the new topology and their fundamental principle are firstly introduced, the method of design ...This paper presents a new inverter based on three-phase Boost/Buck-boost single-stage inverter. The basic configuration of the new topology and their fundamental principle are firstly introduced, the method of design double-loop controller and sliding mode controller are clarified, analyzed and compared in the following. Finally the validity and feasibility of the new topology are tested by simulation. The results indicate that regulation of the voltage transfer ratio and output frequency can be realized optionally by the new converter, furthermore the harmonic distortion of waveform is low. So the inherent drawback of low voltage transfer ratio of traditional converter is effectively settled. This study may provide inspiration for further engineering application.展开更多
Z-source inverter can boost the voltage of the DC-side, allow the two switches of the same bridge arm conducting at the same time and it has some other advantages. The zero-sequence current flows through the fourth le...Z-source inverter can boost the voltage of the DC-side, allow the two switches of the same bridge arm conducting at the same time and it has some other advantages. The zero-sequence current flows through the fourth leg of the three-phase four-leg inverter so the three-phase four-leg inverter can work with unbalanced load. This paper presents a Z-source three-phase four-leg inverter which combines a Z-source network with three-phase four-leg inverter. The circuit uses simple SPWM modulation technique and the fourth bridge arm uses fully compensated control method. The inverter can maintain a symmetrical output voltage when the proposed scheme under the unbalanced load.展开更多
The single photon frequency conversion is investigated theoretically in the system composed of a V-type system chiral coupling to a pair of waveguides. The single photon scattering amplitudes are obtained using the re...The single photon frequency conversion is investigated theoretically in the system composed of a V-type system chiral coupling to a pair of waveguides. The single photon scattering amplitudes are obtained using the real-space Hamiltonian. The calculated results show that the probability of single photon frequency down-or up-conversion can reach a unit by choosing appropriate parameters in the non-dissipative system with perfect chiral coupling.We present a nonreciprocal single photon beam splitter whose frequency of the output photon is different from that of the input photon. The influences of dissipations and non-perfect chiral coupling on the single frequency conversion are also shown. Our results may be useful in designing quantum devices at the single-photon level.展开更多
The aim of this paper is to propose a flexible and accurate methodology for the evaluation of the BIPV （building integrated photovoltaic） potential on industrial building roofs. The use of more realistic and case sp...The aim of this paper is to propose a flexible and accurate methodology for the evaluation of the BIPV （building integrated photovoltaic） potential on industrial building roofs. The use of more realistic and case specific data obtained by accurate technical on-site audits is proved to be of significant importance in the reliability of the proposed methodology results. Moreover, the most recent PV market information is used, considering however that this factor is rapidly changing during the last years, owed to the vast growth of the PV sector. To this end, emphasis is given on the country of Greece, where besides the fact that there is an increase of PV installations; no progress has been met in the use of BIPV systems in the industrial sector, opposite to the situation met in other EU countries. Acknowledging the above, the proposed methodology is currently applied so as to evaluate the BIPV potential of a large industrial zone close to the Greek capital, Athens. The results of this study can be used by both other researchers, for similar evaluations, and energy policy makers, to support the clean energy production concept on the basis of BIPV systems in industrial areas.展开更多
A new control algorithm is presented for digitally controlled dc-dc converters to achieve a fast response under a successive load-change.Under the steady-state condition,the tight voltage regulation is processed by th...A new control algorithm is presented for digitally controlled dc-dc converters to achieve a fast response under a successive load-change.Under the steady-state condition,the tight voltage regulation is processed by the conventional digital PID compensator.If the load disturbance is significant,the controller switches to an optimal control scheme.With the integration of the capacitor current,the proposed algorithm predicts the optimal switch over time based on the charge balance control,and the minimal voltage derivation and recovery time are thus achieved when the load current has a successive load-change.The method for calculating the optimal switch over time is described,and the implementation of the proposed algorithm with a digital controller is treated in detail.Furthermore,the simulation and experiment results are provided to validate the effectiveness of the approaches.展开更多
Due to the low overcurrent capacity of the inverter-based microgrid,traditional overcurrent protect is not suitable for the entire power system including microgrid.A fast detecting method and a whole protection scheme...Due to the low overcurrent capacity of the inverter-based microgrid,traditional overcurrent protect is not suitable for the entire power system including microgrid.A fast detecting method and a whole protection scheme is needed to identify the fault and keep the system stable.This paper proposes a microgrid relay protection scheme combining a fast fault detection algorithm and low voltage ride through(LVRT)strategy.The detection algorithm combines a new harmonic analysis method and impedance delay which can complete fault detection within several milliseconds.Under a fault condition,the LVRT strategy utilizes an enhanced phase-locked loop(EPLL)to allow the microgrid to operate under unbalanced conditions for a period of time.In addition,for the dispatch requirements of power system,it also has communication based power compensation functionality.The scheme given in this paper is verified by simulation,verifying feasibility of its application in practice.展开更多
基金Supported by the Anhui Provincial Natural Science Foundation under Grant Nos 1608085MA05 and 1608085MA09the National Natural Science Foundation of China under Grant Nos 11774262 and 11474003
文摘We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerated and degenerated. By applying the hard-wall boundary condition of the semi-infinite waveguide, it is found that singlephoton polarization conversion can be realized with unit probability for both cases under the ideal condition.Together with the polarization conversion, the frequency conversion of a single photon can also be realized with unit probability in the ideal case if the Λ system is not degenerated.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51877187)the Key Program of University Technology Plan of Hebei Province(Grant No.ZD2017081).
文摘In this paper,battery aging diversity among independent cells was studied in terms of available capacity degradation.During the aging process of LiFePO_(4)batteries,the phenomenon of aging diversity can be observed.When batteries with same specification were charged and discharged repeatedly under the same working conditions,the available capacity of different cell decreased at different rates along the cycle number.In this study,accelerated aging tests were carried out on multiple new LiFePO_(4)battery samples of different brands.Experimental results show that under the same working conditions,the actual available capacity of all cells decreased as the number of aging cycle increased,but an obvious aging diversity was observed even among different cells of same brand with same specification.This aging diversity was described and analysed in detail,and the common aging features of different cells beneath this aging diversity was explored.Considering this aging diversity,a probability density concept was adopted to estimate battery’s state of health(SOH).With this method,a relationship between battery SOH and its aging feature parameter was established,and a dynamic sliding window optimization technique was designed to ensure the optimal quality of aging feature extraction.Finally,the accuracy of this SOH estimation method was verified by random test.
文摘This paper presents a new inverter based on three-phase Boost/Buck-boost single-stage inverter. The basic configuration of the new topology and their fundamental principle are firstly introduced, the method of design double-loop controller and sliding mode controller are clarified, analyzed and compared in the following. Finally the validity and feasibility of the new topology are tested by simulation. The results indicate that regulation of the voltage transfer ratio and output frequency can be realized optionally by the new converter, furthermore the harmonic distortion of waveform is low. So the inherent drawback of low voltage transfer ratio of traditional converter is effectively settled. This study may provide inspiration for further engineering application.
文摘Z-source inverter can boost the voltage of the DC-side, allow the two switches of the same bridge arm conducting at the same time and it has some other advantages. The zero-sequence current flows through the fourth leg of the three-phase four-leg inverter so the three-phase four-leg inverter can work with unbalanced load. This paper presents a Z-source three-phase four-leg inverter which combines a Z-source network with three-phase four-leg inverter. The circuit uses simple SPWM modulation technique and the fourth bridge arm uses fully compensated control method. The inverter can maintain a symmetrical output voltage when the proposed scheme under the unbalanced load.
基金Supported by the Anhui Provincial Natural Science Foundation under Grant No 1608085MA09the National Natural Science Foundation of China under Grant Nos 11774262,61675006,11474003 and 61472282
文摘The single photon frequency conversion is investigated theoretically in the system composed of a V-type system chiral coupling to a pair of waveguides. The single photon scattering amplitudes are obtained using the real-space Hamiltonian. The calculated results show that the probability of single photon frequency down-or up-conversion can reach a unit by choosing appropriate parameters in the non-dissipative system with perfect chiral coupling.We present a nonreciprocal single photon beam splitter whose frequency of the output photon is different from that of the input photon. The influences of dissipations and non-perfect chiral coupling on the single frequency conversion are also shown. Our results may be useful in designing quantum devices at the single-photon level.
文摘The aim of this paper is to propose a flexible and accurate methodology for the evaluation of the BIPV （building integrated photovoltaic） potential on industrial building roofs. The use of more realistic and case specific data obtained by accurate technical on-site audits is proved to be of significant importance in the reliability of the proposed methodology results. Moreover, the most recent PV market information is used, considering however that this factor is rapidly changing during the last years, owed to the vast growth of the PV sector. To this end, emphasis is given on the country of Greece, where besides the fact that there is an increase of PV installations; no progress has been met in the use of BIPV systems in the industrial sector, opposite to the situation met in other EU countries. Acknowledging the above, the proposed methodology is currently applied so as to evaluate the BIPV potential of a large industrial zone close to the Greek capital, Athens. The results of this study can be used by both other researchers, for similar evaluations, and energy policy makers, to support the clean energy production concept on the basis of BIPV systems in industrial areas.
基金Supported by the National Natural Science Foundation of China(51207001)the Anhui Provincial Natural Science Foundation(1308085ME66)
文摘A new control algorithm is presented for digitally controlled dc-dc converters to achieve a fast response under a successive load-change.Under the steady-state condition,the tight voltage regulation is processed by the conventional digital PID compensator.If the load disturbance is significant,the controller switches to an optimal control scheme.With the integration of the capacitor current,the proposed algorithm predicts the optimal switch over time based on the charge balance control,and the minimal voltage derivation and recovery time are thus achieved when the load current has a successive load-change.The method for calculating the optimal switch over time is described,and the implementation of the proposed algorithm with a digital controller is treated in detail.Furthermore,the simulation and experiment results are provided to validate the effectiveness of the approaches.
基金Supported by National Key Research and Development Plan(2016YFB-0900300)National Nature Science Foundation of China(51677162)Natural Scientific Foundation of Hebei Province(E2017203337).
文摘Due to the low overcurrent capacity of the inverter-based microgrid,traditional overcurrent protect is not suitable for the entire power system including microgrid.A fast detecting method and a whole protection scheme is needed to identify the fault and keep the system stable.This paper proposes a microgrid relay protection scheme combining a fast fault detection algorithm and low voltage ride through(LVRT)strategy.The detection algorithm combines a new harmonic analysis method and impedance delay which can complete fault detection within several milliseconds.Under a fault condition,the LVRT strategy utilizes an enhanced phase-locked loop(EPLL)to allow the microgrid to operate under unbalanced conditions for a period of time.In addition,for the dispatch requirements of power system,it also has communication based power compensation functionality.The scheme given in this paper is verified by simulation,verifying feasibility of its application in practice.
