In high-speed railway(HSR)wireless communication,the rapid channel changes and limited high-capacity access cause significant impact on the link performance.Meanwhile,the Doppler shift caused by high mobility leads to...In high-speed railway(HSR)wireless communication,the rapid channel changes and limited high-capacity access cause significant impact on the link performance.Meanwhile,the Doppler shift caused by high mobility leads to the inter-carrier interference.In this paper,we propose a reconfigurable intelligent surface(RIS)-assisted receive spatial modulation(SM)scheme based on the spatial-temporal correlated HSR Rician channel.The characteristics of SM and the phase shift adjustment of RIS are used to mitigate the performance degradation in high mobility scenarios.Considering the influence of channel spatial-temporal correlation and Doppler shift,the effects of different parameters on average bit error rate(BER)performance and upper bound of ergodic capacity are analyzed.Therefore,a joint antenna and RIS-unit selection algorithm based on the antenna removal method is proposed to increase the capacity performance of communication links.Numerical results show that the proposed RIS-assisted receive SM scheme can maintain high transmission capacity compared to the conventional HSR-SM scheme,whereas the degradation of BER performance can be compensated by arranging a large number of RIS-units.In addition,selecting more RIS-units has better capacity performance than activating more antennas in the low signal-to-noise ratio regions.展开更多
The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate （BER） of several coherent and noncoherent digital modulation schemes in the...The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate （BER） of several coherent and noncoherent digital modulation schemes in the correlated Weibull fading channels with nonidentical statisticS. The results are expressed in terms of Meijer＇s Gfunction, which can be easily evaluated numerically. The simulation results are presented to validate the proposed theoretical analysis and to examine the effects of the fading severity on the concerned quantities.展开更多
In this paper,we design a spatial modulation based orthogonal time frequency space(SMOTFS)system to achieve improved transmission reliability and meet the high transmission rate and highspeed demands of future mobile ...In this paper,we design a spatial modulation based orthogonal time frequency space(SMOTFS)system to achieve improved transmission reliability and meet the high transmission rate and highspeed demands of future mobile communications,which fully utilizes the characteristics of spatial modulation(SM)and orthogonal time frequency space(OTFS)transmission.The detailed system design and signal processing of the SM-OTFS system have been presented.The closed-form expressions of the average symbol error rate(ASER)and average bit error rate(ABER)of the SM-OTFS system have been derived over the delay-Doppler channel with the help of the union bounding technique and moment-generating function(MGF).Meanwhile,the system complexity has been evaluated.Numerical results verify the correctness of the theoretical ASER and ABER analysis of the SM-OTFS system in the high signal-to-noise ratio(SNR)regions and also show that the SM-OTFS system outperforms the traditional SM based orthogonal frequency division multiplexing(SM-OFDM)system with limited complexity increase under mobile conditions,especially in high mobility scenarios.展开更多
The state space average model and the large signal models of Pulse Skip Modulation （PSM） mode are given in this paper. Farther more, based on these models and simulations of PSM converter circuits, the analysis of t...The state space average model and the large signal models of Pulse Skip Modulation （PSM） mode are given in this paper. Farther more, based on these models and simulations of PSM converter circuits, the analysis of the characteristics of PSM converter is described in this paper, of which include efficiency, frequency spectrum analysis, output voltage ripple, response speed and interference rejection capability. Compared with PWM control mode, PSM converter has high efficiency, especially with fight loads, quick response, good interference rejection and good EMC characteristic. Improved PSM slightly, it could be a kind of good independent regulating mode during the whole operating process for a DC-DC converter. Finally, some experimental results are also presented in this paper.展开更多
The average zT determines the conversion efficiency,and the power factor plays an important role in average zT value.However,the inadequate electrical conductivity of SnSe materials seriously limits its application.He...The average zT determines the conversion efficiency,and the power factor plays an important role in average zT value.However,the inadequate electrical conductivity of SnSe materials seriously limits its application.Herein,the TaCl_(5)-doped in polycrystalline SnSe_(0.95) materials synthesized using the melting method and combined with spark plasma sintering technology achieves a zT value of 1.64 at 773 K and a record zTave of 0.62 from 323 K to 773 K.The electrical conductivity increases due to the released electron carrier induced by effective TaCl_(5) doping.According to the DFT calculation,the energy band of TaCl_(5)-doped samples is narrowed,which can enhance the electron transport.Besides,the Seebeck coefficient is maintained at an elevated level as a result of the incorporation of the heavy element Ta.Due to the significantly enhanced electrical conductivity and maintained high Seebeck coefficient,the power factor reaches to 622 mW·m^(-1)·K^(-2) at 773 K for the SnSe_(0.95) t 1.75%(in mass)TaCl_(5) sample,which is almost 21 times higher than that of the pristine sample.Simultaneously,a high average power factor value of 334 mW·m^(-1)·K^(-2) for the SnSe_(0.95) t 1.75%(in mass)TaCl_(5) sample from 323 to 773 K was obtained.It is surprisingly found that the Ta element plays another important role to improve the stability of SnSe_(0.95) by forming Ta2Sn3 and removing the low melting point Sn,which usually existed in n-type SnSe samples,resulting in the decreased lattice thermal conductivity.A low lattice thermal conductivity value of 0.24 W·m^(-1)·K^(-1) was also obtained for the SnSe_(0.95) t 2.0%(in mass)TaCl_(5) sample at 773 K due to the multiscale defects.Consequently,the SnSe_(0.95) t 2.0%(in mass)TaCl_(5) sample obtains a peak zT value of 1.64 at 773 K and a record zTave of 0.62 from 323 to 773 K,and the theoretically calculated conversion efficiency reaches 11.2%,it can be utilized for power generation and/or cooling at a broad temperature range.This strategy of introducing high-valence halides with heavy element can optimize the thermoelectric performance for other material systems.展开更多
The nonstationary probability densities of system response of a single-degree- of-freedom system with lightly nonlinear damping and strongly nonlinear stiffness subject to modulated white noise excitation are studied....The nonstationary probability densities of system response of a single-degree- of-freedom system with lightly nonlinear damping and strongly nonlinear stiffness subject to modulated white noise excitation are studied. Using the stochastic averaging method based on the generalized harmonic functions, the averaged Fokl^er-Planck-Kolmogorov equation governing the nonstationary probability density of the amplitude is derived. The solution of the equation is approximated by the series expansion in terms of a set of properly selected basis functions with time-dependent coefficients. According to the Galerkin method, the time-dependent coefficients can be solved from a set of first-order linear differential equations. Then, the semi-analytical formulae of the nonstationary probability density of the amplitude response as well as the nonstationary probability density of the state response and the statistic moments of the amplitude response can be obtained. A van der Pol-Duffing oscillator subject to modulated white noise is given as an example to illustrate the proposed procedures. The effects of the system parameters, such as the linear damping coefficient and the nonlinear stiffness coefficient, on the system response are discussed.展开更多
A correlation overlapping partial transmit sequence(C-OPTS) algorithm is proposed to solve the issue of high complexity of overlapping partial transmit sequence(OPTS) algorithm in suppressing the peak to average power...A correlation overlapping partial transmit sequence(C-OPTS) algorithm is proposed to solve the issue of high complexity of overlapping partial transmit sequence(OPTS) algorithm in suppressing the peak to average power ratio(PAPR) of filter bank multicarrier-offset quadrature amplitude modulation(FBMC-OQAM) signals.The V subblocks in partial transmit sequence(PTS) are regrouped into U combinations according to the correlation coefficient p,and overlapping subblocks are allowed between adjacent groups.The search starts from the first group and sets the phase factors of the subsequent groups to 1.When the phase factors of the non-overlapping subblocks in the first group are determined,the subsequent groups are searched in turn to determine their respective phase factors.Starting from the second data block,the data overlapped with it should be taken into account when determining its optimal phase factor vector.Theoretical analysis and simulation results indicate that compared with the OPTS algorithm,the proposed algorithm can significantly reduce the computational complexity at the cost of slight deterioration of PAPR performance.Meanwhile,compared with the even-odd iterative double-layers OPTS(ID-OPTS) algorithm,it can further reduce the complexity and obtain a better PAPR suppression effect.展开更多
This paper is concerned with the pricing problem of the discrete arithmetic average Asian call option while the discrete dividends follow geometric Brownian motion. The volatility of the dividends model depends on the...This paper is concerned with the pricing problem of the discrete arithmetic average Asian call option while the discrete dividends follow geometric Brownian motion. The volatility of the dividends model depends on the Markov-Modulated process. The binomial tree method, in which a more accurate factor has been used, is applied to solve the corresponding pricing problem. Finally, a numerical example with simulations is presented to demonstrate the effectiveness of the proposed method.展开更多
基金supported in part by National Natural Science Foundation of China under Grant 62461024Jiangxi Provincial Natural Science Foundation of China under Grant 20224ACB202001.
文摘In high-speed railway(HSR)wireless communication,the rapid channel changes and limited high-capacity access cause significant impact on the link performance.Meanwhile,the Doppler shift caused by high mobility leads to the inter-carrier interference.In this paper,we propose a reconfigurable intelligent surface(RIS)-assisted receive spatial modulation(SM)scheme based on the spatial-temporal correlated HSR Rician channel.The characteristics of SM and the phase shift adjustment of RIS are used to mitigate the performance degradation in high mobility scenarios.Considering the influence of channel spatial-temporal correlation and Doppler shift,the effects of different parameters on average bit error rate(BER)performance and upper bound of ergodic capacity are analyzed.Therefore,a joint antenna and RIS-unit selection algorithm based on the antenna removal method is proposed to increase the capacity performance of communication links.Numerical results show that the proposed RIS-assisted receive SM scheme can maintain high transmission capacity compared to the conventional HSR-SM scheme,whereas the degradation of BER performance can be compensated by arranging a large number of RIS-units.In addition,selecting more RIS-units has better capacity performance than activating more antennas in the low signal-to-noise ratio regions.
基金the National High-Tech Research and Development Program (2002AA123032)the Innovative Research Team Program of UESTC, China.
文摘The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate （BER） of several coherent and noncoherent digital modulation schemes in the correlated Weibull fading channels with nonidentical statisticS. The results are expressed in terms of Meijer＇s Gfunction, which can be easily evaluated numerically. The simulation results are presented to validate the proposed theoretical analysis and to examine the effects of the fading severity on the concerned quantities.
基金in part by the National Natural Science Foundation of China under Grant 61771291,Grant 61671278in part by the Key Research and Development Project of Shandong Province under Grant 2018GGX101009,Grant 2019TSLH0202,Grant 2020CXGC010109+1 种基金in part by the National Nature Science Foundation of China for Excellent Young Scholars under Grant 61622111in part by the Project of International Cooperation and Exchanges NSFC under Grant 61860206005.
文摘In this paper,we design a spatial modulation based orthogonal time frequency space(SMOTFS)system to achieve improved transmission reliability and meet the high transmission rate and highspeed demands of future mobile communications,which fully utilizes the characteristics of spatial modulation(SM)and orthogonal time frequency space(OTFS)transmission.The detailed system design and signal processing of the SM-OTFS system have been presented.The closed-form expressions of the average symbol error rate(ASER)and average bit error rate(ABER)of the SM-OTFS system have been derived over the delay-Doppler channel with the help of the union bounding technique and moment-generating function(MGF).Meanwhile,the system complexity has been evaluated.Numerical results verify the correctness of the theoretical ASER and ABER analysis of the SM-OTFS system in the high signal-to-noise ratio(SNR)regions and also show that the SM-OTFS system outperforms the traditional SM based orthogonal frequency division multiplexing(SM-OFDM)system with limited complexity increase under mobile conditions,especially in high mobility scenarios.
基金Supported by the National Natural Science Foundation of China (No.60436030)
文摘The state space average model and the large signal models of Pulse Skip Modulation （PSM） mode are given in this paper. Farther more, based on these models and simulations of PSM converter circuits, the analysis of the characteristics of PSM converter is described in this paper, of which include efficiency, frequency spectrum analysis, output voltage ripple, response speed and interference rejection capability. Compared with PWM control mode, PSM converter has high efficiency, especially with fight loads, quick response, good interference rejection and good EMC characteristic. Improved PSM slightly, it could be a kind of good independent regulating mode during the whole operating process for a DC-DC converter. Finally, some experimental results are also presented in this paper.
基金supported by the Outstanding Youth Fund of Yunnan Province(Grant No.202201AV070005)National Natural Science Foundation of China(Grant No.52162029)National Key R&D Program of China(Grant No.2022YFF0503804).
文摘The average zT determines the conversion efficiency,and the power factor plays an important role in average zT value.However,the inadequate electrical conductivity of SnSe materials seriously limits its application.Herein,the TaCl_(5)-doped in polycrystalline SnSe_(0.95) materials synthesized using the melting method and combined with spark plasma sintering technology achieves a zT value of 1.64 at 773 K and a record zTave of 0.62 from 323 K to 773 K.The electrical conductivity increases due to the released electron carrier induced by effective TaCl_(5) doping.According to the DFT calculation,the energy band of TaCl_(5)-doped samples is narrowed,which can enhance the electron transport.Besides,the Seebeck coefficient is maintained at an elevated level as a result of the incorporation of the heavy element Ta.Due to the significantly enhanced electrical conductivity and maintained high Seebeck coefficient,the power factor reaches to 622 mW·m^(-1)·K^(-2) at 773 K for the SnSe_(0.95) t 1.75%(in mass)TaCl_(5) sample,which is almost 21 times higher than that of the pristine sample.Simultaneously,a high average power factor value of 334 mW·m^(-1)·K^(-2) for the SnSe_(0.95) t 1.75%(in mass)TaCl_(5) sample from 323 to 773 K was obtained.It is surprisingly found that the Ta element plays another important role to improve the stability of SnSe_(0.95) by forming Ta2Sn3 and removing the low melting point Sn,which usually existed in n-type SnSe samples,resulting in the decreased lattice thermal conductivity.A low lattice thermal conductivity value of 0.24 W·m^(-1)·K^(-1) was also obtained for the SnSe_(0.95) t 2.0%(in mass)TaCl_(5) sample at 773 K due to the multiscale defects.Consequently,the SnSe_(0.95) t 2.0%(in mass)TaCl_(5) sample obtains a peak zT value of 1.64 at 773 K and a record zTave of 0.62 from 323 to 773 K,and the theoretically calculated conversion efficiency reaches 11.2%,it can be utilized for power generation and/or cooling at a broad temperature range.This strategy of introducing high-valence halides with heavy element can optimize the thermoelectric performance for other material systems.
基金Project supported by the National Natural Science Foundation of China(No.11025211)the Zhejiang Provincial Natural Science Foundation of China(No.Z6090125)the Special Fund for National Excellent Ph.D.Dissertation and Research Grant Council of Hong Kong City(No.U115807)
文摘The nonstationary probability densities of system response of a single-degree- of-freedom system with lightly nonlinear damping and strongly nonlinear stiffness subject to modulated white noise excitation are studied. Using the stochastic averaging method based on the generalized harmonic functions, the averaged Fokl^er-Planck-Kolmogorov equation governing the nonstationary probability density of the amplitude is derived. The solution of the equation is approximated by the series expansion in terms of a set of properly selected basis functions with time-dependent coefficients. According to the Galerkin method, the time-dependent coefficients can be solved from a set of first-order linear differential equations. Then, the semi-analytical formulae of the nonstationary probability density of the amplitude response as well as the nonstationary probability density of the state response and the statistic moments of the amplitude response can be obtained. A van der Pol-Duffing oscillator subject to modulated white noise is given as an example to illustrate the proposed procedures. The effects of the system parameters, such as the linear damping coefficient and the nonlinear stiffness coefficient, on the system response are discussed.
基金Supported by the National Natural Science Foundation of China(No.61601296,61701295,61801286)the Major Scientific and Technological Innovation Projects in Chengdu(No.2019-YF08-00082-GX)the Talent Program of Shanghai University of Engineering Science(No.2018RC43)。
文摘A correlation overlapping partial transmit sequence(C-OPTS) algorithm is proposed to solve the issue of high complexity of overlapping partial transmit sequence(OPTS) algorithm in suppressing the peak to average power ratio(PAPR) of filter bank multicarrier-offset quadrature amplitude modulation(FBMC-OQAM) signals.The V subblocks in partial transmit sequence(PTS) are regrouped into U combinations according to the correlation coefficient p,and overlapping subblocks are allowed between adjacent groups.The search starts from the first group and sets the phase factors of the subsequent groups to 1.When the phase factors of the non-overlapping subblocks in the first group are determined,the subsequent groups are searched in turn to determine their respective phase factors.Starting from the second data block,the data overlapped with it should be taken into account when determining its optimal phase factor vector.Theoretical analysis and simulation results indicate that compared with the OPTS algorithm,the proposed algorithm can significantly reduce the computational complexity at the cost of slight deterioration of PAPR performance.Meanwhile,compared with the even-odd iterative double-layers OPTS(ID-OPTS) algorithm,it can further reduce the complexity and obtain a better PAPR suppression effect.
文摘This paper is concerned with the pricing problem of the discrete arithmetic average Asian call option while the discrete dividends follow geometric Brownian motion. The volatility of the dividends model depends on the Markov-Modulated process. The binomial tree method, in which a more accurate factor has been used, is applied to solve the corresponding pricing problem. Finally, a numerical example with simulations is presented to demonstrate the effectiveness of the proposed method.
