This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and con...This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.展开更多
In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the...In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the nonzero codewords of C are 2 minimal. Therefore, we obtain a corollary.展开更多
Gliding arc gas discharge plasma was used for the generation of hydrogen from steam reforming of dimethyl ether(DME).A systemic procedure was employed to determine the suitable experimental conditions.It was found tha...Gliding arc gas discharge plasma was used for the generation of hydrogen from steam reforming of dimethyl ether(DME).A systemic procedure was employed to determine the suitable experimental conditions.It was found that DME conversion first increased up to the maximum and then decreased slightly with the increase of added water and air.The increase of total feed gas flow rate resulted in the decrease of DME conversion and hydrogen yield,but hydrogen energy consumption dropped down to the lowest as total feed gas flow rate increased to76 ml·min 1.Larger electrode gap and higher discharge voltage were advantageous.Electrode shape had an important effect on the conversion of DME and production of H2.Among the five electrodes,electrode 2#with valid length of 55 mm and the radian of 34 degrees of the top electrode section was the best option,which enhanced obviously the conversion of DME.展开更多
This paper investigates the structures and properties of one-Lee weight codes and two-Lee weight projective codes over Z4.The authors first give the Pless identities on the Lee weight of linear codes over Z_4.Then the...This paper investigates the structures and properties of one-Lee weight codes and two-Lee weight projective codes over Z4.The authors first give the Pless identities on the Lee weight of linear codes over Z_4.Then the authors study the necessary conditions for linear codes to have one-Lee weight and two-Lee projective weight respectively,the construction methods of one-Lee weight and two-Lee weight projective codes over Z4 are also given.Finally,the authors recall the weight-preserving Gray map from(Z_4~n,Lee weight)to(F_2^(2n),Hamming weight),and produce a family of binary optimal oneweight linear codes and a family of optimal binary two-weight projective linear codes,which reach the Plotkin bound and the Griesmer bound.展开更多
A two-dimensional transient model has been developed to describe the catalytic methane reforming （MSR） coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabat...A two-dimensional transient model has been developed to describe the catalytic methane reforming （MSR） coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabatic operating conditions. The influences of temperature, pressure and steam/carbon （S/C） on enhancement were taken into account. The results showed that the hydrogen mole fraction （dry basis） higher than 94% could be achieved using Li4SiO4, CaO, and HTC as CO2 acceptors at the operating conditions of 550~C and 0.1 MPa. When the reaction temperature varied from 500℃ to 600℃, the initial CO2 capture rates were HTC〉CaO〉Li4SiO4〉LizZrO3, and the saturation rates HTC〉CaO〉Li4SiOg〉Li2ZrO3. Increasing the reaction temperature would improve the CO2 capture rate and available CO2 capacity. For Li4SiO4, although the adsorbing rate increased as the operating temperature increased, the capacity almost did not change. At 550℃, increasing the working pressure could promote the enhancing factors of Li4SiO4,Li2ZrO3 and HTC. There was an optimal steam/carbon ratio between 2-4.5 such that all CaO, Li4SiO4, HTC and Li2ZrO3 would obtain the biggest enhancement for H2 production at the pre-breakthrough stage.展开更多
An experimental and theoretical study of steam reforming of dimethyl ether was carried out in a processor for fuel cell vehicles to explore the effect of temperature gradient and hydrogen content of the processor.A st...An experimental and theoretical study of steam reforming of dimethyl ether was carried out in a processor for fuel cell vehicles to explore the effect of temperature gradient and hydrogen content of the processor.A steady-state,laminar,two-dimensional axi-symmetric model was proposed to investigate the fluid flow,heat transfer and chemical reactions in the dimethyl ether steam reforming processor using porous medium approach.The numerical model was established with Star-CD program using SIMPLE algorithm and finite volume method.Experimental verification of the two-dimensional mathematical model was conducted.The numerical results coincided well with the experimental data.The effects of the parameters on the temperature gradient and hydrogen content of the processor were studied using the numerical model.展开更多
As a novel one-atom-thick carbon allotrope,graphdiyne(GDY)has attracted wide interest in two-dimensional materials owing to its unique feature with a planar layer comprising sp2-and sp-hybridized carbon atoms and a di...As a novel one-atom-thick carbon allotrope,graphdiyne(GDY)has attracted wide interest in two-dimensional materials owing to its unique feature with a planar layer comprising sp2-and sp-hybridized carbon atoms and a direct natural bandgap.A high-quality saturable absorber(SA)based on GDY was successfully fabricated,and the nonlinear saturable absorption properties were investigated.A compact diode-pumped solid-state passively Q-switched laser based on the as-prepared GDY-SA could be operated at 2µm.The Q-switched laser delivered a maximum average output power of 1.29 W at a central wavelength of 1908.41 nm with up to 54.8%slope efficiency.A repetition rate of 91.58 kHz and single pulse energy of 23.08µJ were obtained.This work is the first application of GDY as an SA to generate all-solid-state pulsed lasers.These results indicate that GDY is a promising SA for solid-state pulsed lasers and has further application potential for ultrafast photonic devices in the 2-µm region.展开更多
文摘This paper presents a novel digital dual-loop control scheme of the PWM(PUlse width modulate)inverter. Deadbeat control technique are employed to enhance the performance. Half switching period delayed sampling and control timing strategy is used to improve the system dynamic response. Simulation and experimental results presented in the paper verified the validity of the proposed control scheme.
文摘In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the nonzero codewords of C are 2 minimal. Therefore, we obtain a corollary.
基金Supported by the National Natural Science Foundation of China(21176175,20606023)
文摘Gliding arc gas discharge plasma was used for the generation of hydrogen from steam reforming of dimethyl ether(DME).A systemic procedure was employed to determine the suitable experimental conditions.It was found that DME conversion first increased up to the maximum and then decreased slightly with the increase of added water and air.The increase of total feed gas flow rate resulted in the decrease of DME conversion and hydrogen yield,but hydrogen energy consumption dropped down to the lowest as total feed gas flow rate increased to76 ml·min 1.Larger electrode gap and higher discharge voltage were advantageous.Electrode shape had an important effect on the conversion of DME and production of H2.Among the five electrodes,electrode 2#with valid length of 55 mm and the radian of 34 degrees of the top electrode section was the best option,which enhanced obviously the conversion of DME.
基金supported by the National Natural Science Foundation of China under Grant Nos.61202068 and 11126174Talents youth Fund of Anhui Province Universities under Grant No.2012SQRL020ZDsupported by Key Discipline Construction of Hefei University 2014XK08
文摘This paper investigates the structures and properties of one-Lee weight codes and two-Lee weight projective codes over Z4.The authors first give the Pless identities on the Lee weight of linear codes over Z_4.Then the authors study the necessary conditions for linear codes to have one-Lee weight and two-Lee projective weight respectively,the construction methods of one-Lee weight and two-Lee weight projective codes over Z4 are also given.Finally,the authors recall the weight-preserving Gray map from(Z_4~n,Lee weight)to(F_2^(2n),Hamming weight),and produce a family of binary optimal oneweight linear codes and a family of optimal binary two-weight projective linear codes,which reach the Plotkin bound and the Griesmer bound.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40972102, 50906031)the National Basic Research Program of China ("973" Project) (Grant No. 2010CB227003)
文摘A two-dimensional transient model has been developed to describe the catalytic methane reforming （MSR） coupled with simultaneous CO2 removal by different absorbents under non-isothermal, non-isobaric and non-adiabatic operating conditions. The influences of temperature, pressure and steam/carbon （S/C） on enhancement were taken into account. The results showed that the hydrogen mole fraction （dry basis） higher than 94% could be achieved using Li4SiO4, CaO, and HTC as CO2 acceptors at the operating conditions of 550~C and 0.1 MPa. When the reaction temperature varied from 500℃ to 600℃, the initial CO2 capture rates were HTC〉CaO〉Li4SiO4〉LizZrO3, and the saturation rates HTC〉CaO〉Li4SiOg〉Li2ZrO3. Increasing the reaction temperature would improve the CO2 capture rate and available CO2 capacity. For Li4SiO4, although the adsorbing rate increased as the operating temperature increased, the capacity almost did not change. At 550℃, increasing the working pressure could promote the enhancing factors of Li4SiO4,Li2ZrO3 and HTC. There was an optimal steam/carbon ratio between 2-4.5 such that all CaO, Li4SiO4, HTC and Li2ZrO3 would obtain the biggest enhancement for H2 production at the pre-breakthrough stage.
基金the National Natural Science Foundation of China(No.51208065)the Science and Technology Planning Project of Hunan Province(No.2015JC3056)+1 种基金the Science and Technology Planning Project of Guangdong Province(No.2015B010110005)the Project of Hunan Province key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle(No.KF1506)
基金supported by the National Natural Science Foundation of China (50975169)Shanghai Science Technology Committee (620210029)
文摘An experimental and theoretical study of steam reforming of dimethyl ether was carried out in a processor for fuel cell vehicles to explore the effect of temperature gradient and hydrogen content of the processor.A steady-state,laminar,two-dimensional axi-symmetric model was proposed to investigate the fluid flow,heat transfer and chemical reactions in the dimethyl ether steam reforming processor using porous medium approach.The numerical model was established with Star-CD program using SIMPLE algorithm and finite volume method.Experimental verification of the two-dimensional mathematical model was conducted.The numerical results coincided well with the experimental data.The effects of the parameters on the temperature gradient and hydrogen content of the processor were studied using the numerical model.
基金financially supported by the National Natural Science Foundation of China (11974220, 61635012,61875138, 61961136001, and U1801254)the State Key Research Development Program of China (2019YFB2203503)
文摘As a novel one-atom-thick carbon allotrope,graphdiyne(GDY)has attracted wide interest in two-dimensional materials owing to its unique feature with a planar layer comprising sp2-and sp-hybridized carbon atoms and a direct natural bandgap.A high-quality saturable absorber(SA)based on GDY was successfully fabricated,and the nonlinear saturable absorption properties were investigated.A compact diode-pumped solid-state passively Q-switched laser based on the as-prepared GDY-SA could be operated at 2µm.The Q-switched laser delivered a maximum average output power of 1.29 W at a central wavelength of 1908.41 nm with up to 54.8%slope efficiency.A repetition rate of 91.58 kHz and single pulse energy of 23.08µJ were obtained.This work is the first application of GDY as an SA to generate all-solid-state pulsed lasers.These results indicate that GDY is a promising SA for solid-state pulsed lasers and has further application potential for ultrafast photonic devices in the 2-µm region.
