作者机构：
[Tong Li; Si Liu; FuLiang Xiao] School of Physics and Electronic Sciences,Changsha University of Science and Technology,Changsha 410114,China;[Tong Li; Si Liu; FuLiang Xiao] Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering,Changsha University of Science and Technology,Changsha 410114,China;School of Electrical and Information Engineering,Changsha University of Science and Technology,Changsha 410114,China;[QiWu Yang; YiHua He; QingHua Zhou; ZhongLei Gao; Qian He; Sai Zhang; Chang Yang] 长沙理工大学;[HongMing Yang] 长沙科技大学电气与信息工程学院
摘要：
Whistler mode waves are critical emissions in magnetized plasmas that usually influence the electron dynamics in a planetary magnetosphere.In this paper,we present a unique event in the Martian magnetosphere in which enhanced whistler mode waves(～10-11 V~2/m~2/Hz) with frequency of 0.1 fce-0.5 fce occurred,based on MAVEN data,exactly corresponding to a significant decrease of suprathermal electron fluxes.The diffusion coefficients are calculated by using the observed electric field wave spectra.The pitch angle diffusion coefficient can approach 10-2 s-1,which is much large r,by ～100 times,than the momentum diffusion coefficient,indicating that pitch angle scattering dominates the whistler-electron resonance process.The curre nt results can successfully explain the dropout of the suprathermal electrons in this event.This study provides direct evidence for whistler-driven electron losses in the Martian magnetosphere.
摘要：
Due to the strong absorption of ultraviolet (UV) light, nanoparticles such as zinc oxide (ZnO) can effectively improve the anti-UV aging performance of asphalt. However, the underlying mechanism of aging behaviors in nanoparticle-modified asphalt remains unclear. In this study, we experimentally investigated the anti-UV aging performances of asphalts modified by pure and Mg/Al-doped ZnO (Zn0.97Mg0.03O; Zn0.97Al0.03O). Furthermore, the underlying mechanism is revealed in detail by density functional theory (DFT) and molecular dynamics simulations. The results show that ZnO nanoparticles improve the anti-UV aging performances of asphalt, while this improvement is further enhanced by Mg/Al doping. Besides UV absorption of nanoparticles, electron transfer from nanoparticles to asphalt molecules, as revealed by DFT, is found to play a crucial role. This electron transfer can lower the reaction energy barrier for dehydrogenation reactions, facilitating oxidation. Meanwhile, it also can disperse the aged asphaltene by increasing the interaction energy, thereby further improving the anti-UV aging performance. Compared to pure ZnO, Mg/Al doping reduces the electron transfer to the asphaltene, which leads to reduced asphalt oxidation and thus better anti-UV aging improvements. The underlying mechanism established in the present work is useful to understand and protect UV aging of asphalt.
通讯机构：
[Liu, YR ] C;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Peoples R China.
摘要：
Although there have been reports showing the modification effect of carbon nanomaterials on asphalt, there are few studies on whether carbon nanomaterials and polymers can have synergistic modification effects on asphalt. At the same time, the complex composition of asphalt makes it difficult to determine the interface mechanism between the modifier and the asphalt. In this study, graphene oxide (GO) and styrene–butadiene–styrene block copolymer (SBS) were selected as modifiers. A combined experimental and molecular simulation research method was used to study the synergistic modification effect and the interface mechanism between the modifier and the asphalt. The results show that the modification effect of GO/SBS incorporated into asphalt is significantly superior to that of GO or SBS incorporated individually and GO/SBS has a synergistic modification effect. Although the binding strength between SBS and asphalt is weak, the GO surface (GO (0 0 1)) can simultaneously bind with SBS and asphalt, increasing the binding strength of SBS and asphalt as well as promoting the dispersion of SBS in asphalt, so that GO/SBS shows a synergistic modification effect and improves properties such as low-temperature ductility, rheology and storage stability at macroscopic level. Intercalated and exfoliated structure can be formed between GO side (GO (0 1 0)) and asphalt, which improves the anti-aging properties of the asphalt. Physical bonding is the main interface binding for GO/SBS compound-modified asphalt. GO bonds to asphalt or SBS by hydrogen bonds and there are only dispersion forces between SBS and asphalt, resulting in a higher binding strength between GO and asphalt or SBS than between SBS and asphalt.
摘要：
- We investigate the localized magnetic state in the tilted Dirac cone system, wherein a lattice staggered potential (LSP) is introduced to create a gap between the conduction and valence bands. Our findings reveal that the breaking of symmetry between the sublattices results in depletion of the magnetic region of the impurity for positive LSP values, while a sharp strip is formed for negative LSP values with an increase in the tilt of the Dirac cone. Interestingly, within the magnetic region, the magnetic moment of the impurity remains constant at 0.8 Bohr magneton irrespective of the sign of LSP. However, the magnetic susceptibility at the edge of the magnetic region displays inconsistent behavior for positive and negative LSP values. We also analyze in detail the variations in the magnetic region, magnetic moment, and magnetic susceptibility with LSP strength at a fixed tilt.Copyright symbolscript 2023 EPLA
期刊：
International Journal of Advanced Computer Science and Applications,2023年14(9):226-234 ISSN：2158-107X
作者机构：
[Chen D.; Tang L.; Hu Z.; Chen Y.; Liu S.; Zhao D.] School of Physics and Electronic Science, Changsha University of Science & Technology, Changsha, 410114, China
关键词：
aluminum profiles surface defect detection;convolutional block attention module;lightweight and fast spatial pyramid pooling structure;ShuffleNetv2;YOLOv5
摘要：
The security and reliability of data transmission between IoT devices are considered to be major challenges in the development of IoT technology. This paper presents a low-power, low-cost RISC-V processor for IoT applications with an integrated hybrid encryption accelerator, which can achieve efficient and secure encryption and decryption of data transmitted between IoT devices. The hybrid encryption accelerator, which uses the SM3 and the SM4, respectively, as hash and symmetric encryption algorithms, achieves a balance between encryption security, high speed, and key-management convenience. Both the processor and encryption accelerator are designed using the Verilog HDL language and are subsequently implemented and evaluated on both FPGA and ASIC platforms. The performance of the proposed processor and that of the Hummingbird E203 and the XuanTie E902 are compared. It is shown that, on the FPGA platform, the total resource utilization rate is reduced by 39.1 similar to 66.2%. In a 90 nm CMOS process, it is shown that the power efficiency of the proposed processor is increased by 10 similar to 34.8% and the circuit area is reduced by 32.5 similar to 57.1%.
摘要：
The distributed capacitance inside the quartz flexible accelerometer (QFA) coupled the high frequency voltage excitation signal in the differential capacitance detection circuit to the torquer coil, and superimposes the torquer driving current to form the driving noise. In this study, the values of the distributed capacitance inside the QFA were simulated. According to the formation mechanism of the QFA driving noise, the equivalent circuit model of the driving noise is established, and the driving noise characteristics of the detection circuit with single excitation and double excitation source are analyzed. The theoretical and experimental results show that the electric field coupled driving noise transmission system is a first-order system with high-pass characteristics. The driving noise of the single excitation detection circuit is larger than that of the dual excitation detection circuit (DEDC), and the DEDC can reduce the driving noise by 39.77% when the QFA shell is grounded. The equivalent acceleration of the electric field coupled driving noise is between tens of & mu;g to hundreds of mg, which is one of the important noise sources that affect the measurement accuracy of the QFA. A measure was proposed to suppress the high-frequency driving noise by adding a low-pass filter after the sampling output of the driving current, which can reduce the driving noise to 1.85 & mu;g and effectively reduce the influence of the driving noise on the measurement accuracy of the QFA.
摘要：
In this article, a 1.2-kV-rated double-trench 4H-SiC MOSFET with an integrated low-barrier diode (DT-LBDMOS) is proposed which eliminates the bipolar degradation of the body diode and reduces switching loss while increasing avalanche stability. A numerical simulation verifies that a lower barrier for electrons appears because of the LBD; thus, a path that makes it easier for electrons to transfer from the N+ source to the drift region is provided, finally eliminating the bipolar degradation of the body diode. At the same time, the LBD integrated in the P-well region weakens the scattering effect of interface states on electrons. Compared with the gate p-shield trench 4H-SiC MOSFET (GPMOS), the reverse on-voltage (V(F)) is reduced from 2.46 V to 1.54 V; the reverse recovery charge (Q(rr)) and the gate-to-drain capacitance (C(gd)) are 28% and 76% lower than those of the GPMOS, respectively. The turn-on and turn-off losses of the DT-LBDMOS are reduced by 52% and 35%. The specific on-resistance (R(ON,sp)) of the DT-LBDMOS is reduced by 34% due to the weaker scattering effect of interface states on electrons. The HF-FOM (HF-FOM = R(ON,sp) × C(gd)) and the P-FOM (P-FOM = BV(2)/R(ON,sp)) of the DT-LBDMOS are both improved. Using the unclamped inductive switching (UIS) test, we evaluate the avalanche energy of devices and the avalanche stability. The improved performances suggest that DT-LBDMOS can be harnessed in practical applications.
作者机构：
[Chen, Xue-Kun; Zhang, En -Ming] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Wu, Dan] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Peoples R China.;[Chen, Ke-Qiu] Hunan Univ, Sch Phys & Elect, Dept Appl Phys, Changsha 410082, Peoples R China.
摘要：
Motivated by the synthesized Cu4TiSe4 with ultralow room-temperature thermal conductivity [Angew. Chem., Int. Ed. 60, 9106 (2021)], we systematically investigate its thermoelectric (TE) properties via combining Boltzmann transport equations and first-principles calculations. The results show that the thermal conductivity of Cu4TiSe4 determined considering only three-phonon scattering is reduced by about 40% after including four-phonon scattering at room temperature, indicating the importance of four-phonon scattering in phonon transport. On the other hand, the coexistence of high dispersion and valley degeneracy at the top valence band in the electronic structure causes a high power factor. Consequently, the isotropic figure of merit (ZT) value of 1.5 at 500 K is captured in the p-type doped Cu4TiSe4 . In addition, the value of ZT can be further enhanced to 2.2 by applying 2.25% triaxial tensile strain, which is ascribed to the remarkably enhanced four-phonon scattering processes induced by the tensile strain. Meanwhile, the significant suppression of thermal conductivity allows the optimal carrier concentration for the ZT peak to be reduced, which is of important practical significance for the experimental preparation of Cu4TiSe4 -based TE devices. Our results pave a way for the design of adjustable medium-temperature TE devices.
通讯机构：
[Luo, XB ] Z;Zhejiang Sci Tech Univ, Dept Phys, Hangzhou 310018, Peoples R China.;Jinggangshan Univ, Sch Math & Phys, Jian 343009, Jiangxi, Peoples R China.
摘要：
We investigate both analytically and numerically the scattering of one-dimensional quantum droplets by a Pöschl-Teller reflectionless potential well, confirming that there is a sharp transition between full reflection and full transmission at a certain critical incident speed for both small droplets and large flat-top droplets. We observe sharp differences between small quantum droplet scattering and large quantum droplet scattering. The scattering of small quantum droplets is similar to that of solitons, where a spatially symmetric trapped mode is formed at the critical speed, whereas for large quantum droplets a spatially asymmetric trapped mode is formed. Additionally, a nonmonotonic dependence of the critical speed on the atom number is identified: On the small-droplet side, the critical speed increases with the atom number, while in the flat-top regime, the critical speed decreases with increasing atom number. Strikingly, the scattering excites internal modes below the particle-emission threshold, preventing the quantum droplets from emitting radiation upon interaction with the potential. Analysis of the small-amplitude excitation spectrum shows that as the number of particles increases, it becomes increasingly difficult to emit particles out of the droplet during scattering, while radiation from solitons cannot be completely avoided. Finally, we study the collision of two quantum droplets at the reflectionless potential, revealing the role of the π -phase difference generator played by the reflectionless potential.
作者机构：
[Chen, Zhuo; Ou, SD; Ou, Shaoduan] Cent South Univ, Sch Energy Sci & Engn, Changsha, Peoples R China.;[Mo, Kewei] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Peoples R China.
通讯机构：
[Ou, SD ] C;Cent South Univ, Sch Energy Sci & Engn, Changsha, Peoples R China.
关键词：
Birefringence;Cornea;Haidinger’s brushes (HB);Phase shift;Polarization;Time constant;Transition process
摘要：
Starting from the dynamic feature of the vision process and taking into account the time constants of the polarization-dependent process of cones, this study proposed a physical model that can mathematically describe the transient nature of Haidinger's brushes (HB). A saturated exponential growth function was proposed to describe the dynamic process, and the corresponding formulas were derived and discussed. The sensitivities of both static and rotating HB were considered in the model, and the visibility of HB was also investigated. Additionally, the impact of the cornea on the visions of HB was examined by using this model. Analytical results reveal that there exist two types of patterns in the rotating HB phenomenon. The visual perception of the rotating HB is related to the magnitude and interaction of these two patterns, as well as the corneal phase shift. The rotation orientation reversal at large corneal phase shifts observed by some researchers can also be explained by the model. The results are consistent with experimental observations and might help with the clinical diagnosis of macula disorders and corneal abnormalities.
摘要：
The performance of monolayer two-dimensional SiC MOSFET with various concentration of ptype doping in source/drain region and various lengths of channel were investigated based on the density-functional theory method. All MOSFETs could realize dynamic turn-off. The maximum ON-state current were up to 1152.8 mu A/mu m and 1731.4 mu A/mu m for 4.1 nm and 5.1 nm SiC MOSFET with 5 x 1020 cm-2 doping concentration, respectively, which could satisfy the requirement of the high-performance devices outlined by ITRS for production year 2028. In addition, the various parameters (transmission spectra, the intrinsic gate capacitance and so on) of MOSFETs were studied. Moreover,the LDOS and spectral current under ON-state voltage were researched to further explore the physical mechanism of the MOSFETs. Furthermore, the study found that the current increased as the temperature increasing, the current value and the temperature difference between left and right electrode at the fixed bias voltage and gate voltage were not related.
