MnNiGe：Fe ribbon samples are prepared. Partial Ni-and Mn-substitution of Fe element can both induce the antiferromagnetic-ferromagnetic conversion in the Ti Ni Si-type state of these MnNiGe：Fe ribbon systems. It is ...MnNiGe：Fe ribbon samples are prepared. Partial Ni-and Mn-substitution of Fe element can both induce the antiferromagnetic-ferromagnetic conversion in the Ti Ni Si-type state of these MnNiGe：Fe ribbon systems. It is found out, however, that some factors such as annealing, temperature variation process field-cycling, substituted site and magnetic field can affect the conversion and competition between the antiferromagnetic and ferromagnetic states in these ribbons. Therefore, in this paper these major influencing factors are studied systematically and further discussed are the related magnetic and magnetocaloric properties in MnNiGe：Fe ribbon systems.展开更多
The energy conversion optimization control strategy is presented for a family of horizontal-axis variablespeed fixed-pitch wind energy conversion systems,working in the partial load region.The system uses a variablesp...The energy conversion optimization control strategy is presented for a family of horizontal-axis variablespeed fixed-pitch wind energy conversion systems,working in the partial load region.The system uses a variablespeed wind turbine(VSWT)driving a squirrel-cage induction generator(SCIG)connected to a grid.A new maximum power point tracking(MPPT)approach is proposed based on the extremum seeking control principles under the assumption that the wind turbine model and its parameters are poorly known.The aim is to drive the average position of the operation point close to optimality.Here the wind turbulence is used as search disturbance instead of inducing new sinusoidal search signals.The discrete Fourier transform(DFT)process of some available measures estimates the distance of operation point to optimality.The effectiveness of the proposed MPPT approach is validated under different operation conditions by numerical simulations in MATLAB/SIMULINK.The simulation results prove that the new approach can effectively suppress the vibration of system and enhance the dynamic performance of system.展开更多
Most reverse conversions in Residue Number Systems (RNS) are based on the Chinese Remainder Theorem (CRT) and the Mixed Radix Conversion (MRC). The complexity of the circuitry of the CRT is high due to the large modul...Most reverse conversions in Residue Number Systems (RNS) are based on the Chinese Remainder Theorem (CRT) and the Mixed Radix Conversion (MRC). The complexity of the circuitry of the CRT is high due to the large modulo-M operation. The MRC has a simple circuitry but it’s a sequential process in nature. The purpose of this research is to obtain an efficient reverse conversion method to reduce the computational overhead found in the conventional reverse conversion algorithms. In this paper, new algorithms for reverse conversion in RNS for four-moduli set and five-moduli set have been proposed and their correctness evaluated. Numerical evaluations to ascertain the correctness and simplicity of the algorithm have been presented. These algorithms have fewer multiplicative index operations than those in the conventional CRT and MRC. The large modulo-M operation has been eliminated which reduces the computational overhead.展开更多
In this work we study all-optical multi-channel return-to-zero （RZ）-on-off keying （OOK） to nonreturn-to-zero （NRZ）-OOK format conversion in single uniform fiber Bragg grating （FBG） for mixed line-rate dense wa...In this work we study all-optical multi-channel return-to-zero （RZ）-on-off keying （OOK） to nonreturn-to-zero （NRZ）-OOK format conversion in single uniform fiber Bragg grating （FBG） for mixed line-rate dense wave- length-division multiplexing systems using mathematical simulations. Forty and 20 Gbit/s RZ-OOK signals with 33% and 50% duty cycles are converted to NRZ-OOK signals in single uniform FBG with 21~ reflectivity. Impact of amplitude noise from FBG contrast profile on modulation format conversion efficiency is also studied.展开更多
Radiative thermoelectric energy converters, which include thermophotovoltaic cells, thermoradiative cells, electroluminescent refrigerators, and negative elec- troluminescent refrigerators, are semiconductor p-n devic...Radiative thermoelectric energy converters, which include thermophotovoltaic cells, thermoradiative cells, electroluminescent refrigerators, and negative elec- troluminescent refrigerators, are semiconductor p-n devices that either generate electricity or extract heat from a cold body while exchanging thermal radiation with their surroundings. If this exchange occurs at micro or nanoscale distances, power densities can be greatly enhanced and near-field radiation effects may improve performance. This review covers the fundamentals of near-field thermal radiation, photon entropy, and none- quilibrium effects in semiconductor diodes that underpin device operation. The development and state of the art of these near-field converters are discussed in detail, and remaining challenges and opportunities for progress are identified.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 51261022, 51561023 and 51671097)the Jiangxi Provincial Graduate Student Innovation Special Funds Project (Grant No. YC2015-S310)the Graduate Student Innovation Special Funds Project of Nanchang Hangkong University (Grant No. YC2015007)
文摘MnNiGe：Fe ribbon samples are prepared. Partial Ni-and Mn-substitution of Fe element can both induce the antiferromagnetic-ferromagnetic conversion in the Ti Ni Si-type state of these MnNiGe：Fe ribbon systems. It is found out, however, that some factors such as annealing, temperature variation process field-cycling, substituted site and magnetic field can affect the conversion and competition between the antiferromagnetic and ferromagnetic states in these ribbons. Therefore, in this paper these major influencing factors are studied systematically and further discussed are the related magnetic and magnetocaloric properties in MnNiGe：Fe ribbon systems.
基金Supported by the National Basic Research Program("973" Program)(2007CB210303)the Research Funding of Nanjing University of Aeronautics and Astronautrics(NP2011011)
文摘The energy conversion optimization control strategy is presented for a family of horizontal-axis variablespeed fixed-pitch wind energy conversion systems,working in the partial load region.The system uses a variablespeed wind turbine(VSWT)driving a squirrel-cage induction generator(SCIG)connected to a grid.A new maximum power point tracking(MPPT)approach is proposed based on the extremum seeking control principles under the assumption that the wind turbine model and its parameters are poorly known.The aim is to drive the average position of the operation point close to optimality.Here the wind turbulence is used as search disturbance instead of inducing new sinusoidal search signals.The discrete Fourier transform(DFT)process of some available measures estimates the distance of operation point to optimality.The effectiveness of the proposed MPPT approach is validated under different operation conditions by numerical simulations in MATLAB/SIMULINK.The simulation results prove that the new approach can effectively suppress the vibration of system and enhance the dynamic performance of system.
文摘Most reverse conversions in Residue Number Systems (RNS) are based on the Chinese Remainder Theorem (CRT) and the Mixed Radix Conversion (MRC). The complexity of the circuitry of the CRT is high due to the large modulo-M operation. The MRC has a simple circuitry but it’s a sequential process in nature. The purpose of this research is to obtain an efficient reverse conversion method to reduce the computational overhead found in the conventional reverse conversion algorithms. In this paper, new algorithms for reverse conversion in RNS for four-moduli set and five-moduli set have been proposed and their correctness evaluated. Numerical evaluations to ascertain the correctness and simplicity of the algorithm have been presented. These algorithms have fewer multiplicative index operations than those in the conventional CRT and MRC. The large modulo-M operation has been eliminated which reduces the computational overhead.
基金supported by the European Social Fund within the Project No.2013/0012/1DP/1.1.1.2.0/13/APIA/VIAA/051
文摘In this work we study all-optical multi-channel return-to-zero （RZ）-on-off keying （OOK） to nonreturn-to-zero （NRZ）-OOK format conversion in single uniform fiber Bragg grating （FBG） for mixed line-rate dense wave- length-division multiplexing systems using mathematical simulations. Forty and 20 Gbit/s RZ-OOK signals with 33% and 50% duty cycles are converted to NRZ-OOK signals in single uniform FBG with 21~ reflectivity. Impact of amplitude noise from FBG contrast profile on modulation format conversion efficiency is also studied.
文摘Radiative thermoelectric energy converters, which include thermophotovoltaic cells, thermoradiative cells, electroluminescent refrigerators, and negative elec- troluminescent refrigerators, are semiconductor p-n devices that either generate electricity or extract heat from a cold body while exchanging thermal radiation with their surroundings. If this exchange occurs at micro or nanoscale distances, power densities can be greatly enhanced and near-field radiation effects may improve performance. This review covers the fundamentals of near-field thermal radiation, photon entropy, and none- quilibrium effects in semiconductor diodes that underpin device operation. The development and state of the art of these near-field converters are discussed in detail, and remaining challenges and opportunities for progress are identified.
