摘要:
We investigate the impact of Raman scattering on pure quartic solitons (PQSs) in an optical fiber with quartic dispersion. An analytical expression of the Raman-induced frequency shift (RWS) of a PQS is obtained by using the variational approach with the Gaussian function ansatz. We find the RIFS of a PQS is inversely proportional to the sixth power of pulse width, when the fiber is short enough. The RWS of a PQS is more sensitive to the pulse width, compared with that of a conventional soliton which is inversely proportional to the fourth power of pulse width. The theoretical predictions show good agreement with numerical results. In addition, we also discuss the RIFS of the other three typical pulses with the same peak power and pulse width as the PQS. These results provide a thorough understanding of the role of higher-order nonlinear effects on the propagation dynamics of PQSs. (C) 2022 Optica Publishing Group
期刊:
Fuzzy Sets and Systems,2022年426:27-45 ISSN:0165-0114
通讯作者:
Li, Long
作者机构:
[Li, Long] Hengyang Normal Univ, Coll Math & Stat, Hengyang, Hunan, Peoples R China.;[Long, Zuqiang] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang, Hunan, Peoples R China.;[Ying, Hao] Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA.;[Qiao, Zhijun] Univ Texas Rio Grande Valley, Dept Math, Edinburg, TX 78539 USA.
通讯机构:
[Li, Long] H;Hengyang Normal Univ, Coll Math & Stat, Hengyang, Hunan, Peoples R China.
摘要:
FeP2 and P are promising anode material for lithium and sodium ion storage, due to the high theoretical capacity. However, poor electric conductivity and severe volume expansion limit its actual performance. Herein, we prepared a flexible self-supporting anode material which is consist of FeP2, P and C heterostructure nanofibers with diameter of 150.0-200.0 nm named FeP2 & nbsp;@CNs-700. Here, well-dispersed FeP2 & nbsp;nanoparticles and amorphous phosphorus are confined in carbon nanofiber skeleton, which enhance the material's electron/ion transport and structure stability. As a result, The FeP2 & nbsp;@CNs-70 0 exhibits a high capacity (1132.2 mAh g & nbsp;(- 1) at 0.1 A g & nbsp;(- 1)& nbsp;for lithium ion batteries, 680.8 mAh g & nbsp;(- 1 & nbsp;)at 0.1 A g & nbsp;(- 1)& nbsp;for sodium ion batteries), excellent cycle stability (a capacity retention of 84.6% at 0.5 A g & nbsp;(- 1)& nbsp;after 500 cycles for LIBs, 300.1 mAh g & nbsp;(- 1)& nbsp;at 1.0 A g & nbsp;(- 1)& nbsp;after 400 cycles for SIBs), outstanding rate performance (461.2/227.9 mAh g & nbsp;(- 1)& nbsp;at high current density of 10.0 A g & nbsp;(- 1)& nbsp;for Li/Na-ion battery, respectively) and high initial coulombic efficiency (87.3% for LIBs and 74.5% for SIBs), indicating a promising candidate for high capacity anodes.& nbsp;(c) 2021 Elsevier Ltd. All rights reserved.
关键词:
Radon concentration in water;RAD7;H2O accessory;Bubbling method;Conversion coefficient;Drying tube
摘要:
Durridge Company offers RAD7 and H2O accessory to measure the radon concentration in water based on bubbling method. There are two types of small sample bottles: 40 mL and 250 mL. The company also provided a big bottle with the volume of 2500 mL to measure the radon concentration in water. For the 40 mL and 250 mL sample bottles, the conversion coefficients are 25 and 4, respectively. The small drying tube of water accessory contains only 30 g desiccant, which makes it inconvenient to measure for a long time and needs to be replaced frequently. Besides, the 2500 mL sample bottle with big drying tube needs longer response time. In this paper, a big drying tube with long lifetime is utilized to measure the radon concentration in water. Generally, the response time and the sensitivity depend on the volume of the sample bottles and the gas circuit, so it is important to obtain the conversion coefficients under different conditions to meet different measurement demands. A novel model is proposed for describing the radon concentration in the gas circuit to obtain the con -version coefficients for any volume of sample bottle and drying tube. By choosing the appropriate time of bubbling and measuring, this model can be utilized to obtain the radon concentration in water.
通讯机构:
[Javed Rehman] D;[Kamel Eid] G;Department of Physics, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS), Quetta 87300, Baluchistan, Pakistan<&wdkj&>Gas Processing Center (G.P.C.), College of Engineering, Qatar University, Doha 2713, Qatar
关键词:
V4C3;MXene;Li-ion battery;Na-ion battery;electrochemical energy storage;DFT
摘要:
Abstract: Li-ion batteries (LIBs) and Na-ion batteries (SIBs) are deemed green and efficient electrochemical energy storage and generation devices; meanwhile, acquiring a competent anode remains a serious challenge. Herein, the density-functional theory (DFT) was employed to investigate the performance of V4C3 MXene as an anode for LIBs and SIBs. The results predict the outstanding electrical conductivity when Li/Na is loaded on V4C3. Both Li2xV4C3 and Na2xV4C3 (x = 0.125, 0.5, 1, 1.5, and 2) showed expected low-average open-circuit voltages of 0.38 V and 0.14 V, respectively, along with a good Li/Na storage capacity of (223 mAhg−1) and a good cycling performance. Furthermore, there was a low diffusion barrier of 0.048 eV for Li0.0625V4C3 and 0.023 eV for Na0.0625V4C3, implying the prompt intercalation/extraction of Li/Na. Based on the findings of the current study, V4C3-based materials may be utilized as an anode for Li/Na-ion batteries in future applications. Keywords: V4C3; MXene; Li-ion battery; Na-ion battery; electrochemical energy storage; DFT
作者机构:
[Jiang, Xi; Wang, Xinwen; Tang, Shiqing] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.;[Wang, Xinwen] Hunan Normal Univ, Key Lab Low Dimens Quantum Struct & Quantum Contr, Changsha 410081, Peoples R China.;[Zhao, Xingdong] Henan Normal Univ, Sch Phys, Xinxiang 453000, Henan, Peoples R China.
通讯机构:
[Xinwen Wang] C;College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, China<&wdkj&>Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha 410081, China
摘要:
Abstract: We propose a theoretical model for realizing a photonic two-qubit phase gate in cavity QED using a one-step process. The fidelity and probability of success of the conditional quantum phase gate is very high in the presence of cavity decay. Our scheme only employs one two-level atom, and thus is much simpler than other schemes involving multi-level atoms. This proposal can also be applied to generate two-mode squeezed states; therefore, we give three examples, i.e., the two-mode squeezed vacuum state, two-mode squeezed odd coherent state, and two-mode squeezed even coherent state, to estimate the variance of Duan’s criterion when taking into account cavity decay. It is shown that the variance is smaller than 2 for the three squeezed states in most cases. Furthermore, we utilize logarithmic negativity to measure the entanglement, and find that these squeezed states have very high degrees of entanglement. Keywords: bimodal cavity; two-level atom; phase gate; squeezed state; one-step
作者机构:
[Tang, Zhenkun; Deng, Xiaohui] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Hunan, Peoples R China.
通讯机构:
[Deng, X.] C;College of Physics and Electronic Engineering, China
摘要:
The ultra-wide single spin states are of importance for ideal magnetic storage materials and spin injection sources. Here, a new type of CrOX (X= Cr, Br, I) monolayer has been revealed. We find that the basic constructive units for such new monolayers are four-coordinated, almost never being reported until now. More interestingly, they are half-metals and have an ultra-wide single spin channel in their electronic band structures. Monte Carlo simulations show that the Curie temperatures of three monolayers are relatively low, however they can be enhanced to exceed the liquid nitrogen temperature under strain or hole doping. The four-coordinated Cr compounds predicted here may open a new windows for exploring high spin-polarized half-metals. Copyright (C) 2022 EPLA
通讯机构:
[Li, L ] H;Hengyang Normal Univ, Coll Comp Sci & Technol, Hengyang 421002, Peoples R China.;Hengyang Normal Univ, Hunan Prov Key Lab Intelligent Informat Proc & Ap, Hengyang 421002, Peoples R China.
关键词:
Differential power analysis;Hamming weight;Ghost peaks;AES
摘要:
Differential power analysis (DPA) is disturbed by ghost peaks. There is a phenomenon that the mean absolute difference (MAD) value of the wrong key is higher than the correct key. We propose a compressed key guessing space (CKGS) scheme to solve this problem and analyze the AES algorithm. The DPA based on this scheme is named CKGS-DPA. Unlike traditional DPA, the CKGS-DPA uses two power leakage points for a combined attack. The first power leakage point is used to determine the key candidate interval, and the second is used for the final attack. First, we study the law of MAD values distribution when the attack point is AddRoundKey and explain why this point is not suitable for DPA. According to this law, we modify the selection function to change the distribution of MAD values. Then a key-related value screening algorithm is proposed to obtain key information. Finally, we construct two key candidate intervals of size 16 and reduce the key guessing space of the SubBytes attack from 256 to 32. Simulation experimental results show that CKGS-DPA reduces the power traces demand by 25% compared with DPA. Experiments performed on the ASCAD dataset show that CKGS-DPA reduces the power traces demand by at least 41% compared with DPA.
期刊:
Physica E: Low-dimensional Systems and Nanostructures,2022年135:114978- ISSN:1386-9477
通讯作者:
Liu, Zhaosen
作者机构:
[Liu, Zhaosen] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.;[Yang, Hongxin] Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Div Magnet Mat & Devices, Ningbo 315201, Peoples R China.;[Yang, Hongxin] Univ Chinese Acad Sci, Ctr Mat Sci & Optoelect Engn, Beijing 100049, Peoples R China.
通讯机构:
[Liu, Zhaosen] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.
关键词:
Optimized quantum Monte Carlo method;Antiferromagnetic skyrmion crystal;Two-dimensional square magnet
摘要:
The formations of individual antiferromagnetic (AF) skyrmions and AF skyrmionic lattices on two-dimensional (2D) magnets with square crystal structure are debatable in recent years, for only an isolated skyrmion can be generated in such systems if classical Monte Carlo (CMC) method is employed. For the sake, we apply here an optimized quantum Monte Carlo approach to a 2D square magnet where the AF Heisenberg exchange (HE) and Dzyaloshinskii-Moriya (DM) interactions co-exist. Consequently, the computing program converges to the equilibrium states with appreciable computational speed, and the results obtained in the last one iteration are able to accurately produce well symmetric and periodic AF skyrmionic lattices (SLs) at elevated temperatures when a considerably strong external magnetic field is exerted perpendicular to the 2D monolayer. Moreover, each of these AF SLs can be decomposed into two almost identical ferromagnetic (FM) SLs, and the distribution of topological charge density also forms symmetric lattice with the same periodicity as the AF SL, dividing the AF SL into several areas of distinct spin configurations. The reasons why the OQMC approach can work beyond CMC method are explained in the Discussion Section.
通讯机构:
[Qing-Xia Ge; Wen-Jin Yin] S;School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China<&wdkj&>School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China<&wdkj&>Key Laboratory of Intelligent Sensors and Advanced Sensing Materials of Hunan Province, Hunan University of Science and Technology, Xiangtan 411201, China
摘要:
Low activity and poor product selectivity of CO(2) reduction have seriously hampered its further practical application. Introducing p-block atoms to the catalyst is regarded as a promising strategy due to the versatility of p orbitals and diversity of p-block elements. Here, we systematically studied the influence of p-block atom X (X = C, N, O, S, and Se) on CO(2) catalytic properties on a Sn(200) surface by first-principles calculation. Our work shows that all the p-block atoms are relative stable with E(f) in the range of -5.11 to -3.59 eV. Further calculation demonstrates that the diversity of the p-block atoms results in unique CO(2) electrocatalytic activity and product selectivity. Interestingly, the p-block C atom shows bi-functional activity to form two-electron products HCOOH and CO, with the corresponding energy barriers remarkably low at about 0.19 eV and 0.28 eV. In particular, the p-block S(Se) atom appears to have striking HCOOH selectivity, with the energy barrier to form HCOOH only a quarter of that to form the CO product. This unusual behavior is mainly attributed to the adsorption strength and frontier orbital interaction between the p-block atom and intermediates. These findings can effectively provide a valuable insight into the design of highly efficient CO(2) electrocatalyst.
关键词:
Adsorption and desorption;Doped graphene;Molecular dynamics
摘要:
Two-dimensional materials have promised an important application as gas sensors due to their big surface areas. Although it's conceptually attractive, the real performance may be dramatically altered at finite temperatures. Therefore, to find out the underlying physical mechanism or dynamics at finite temperatures is of importance before any actual application. Here, we find that boron-doped graphene (BG) should be an ideal sensor to detect gas molecules such as NO2. Our results from first-principle molecular dynamics simulations show NO2 molecule can adsorb stably on BG at room temperature. Furthermore, its desorption time from BG is in the level of micro-seconds (ms), which has fully met the standards of industrial applications. The desorption time will be further decreased to the pico-seconds (ps) level at higher temperature, promising an opportunity for BG to detect the NO2 molecule using more accurate and sensitive measuring techniques, for example femtoseconds laser or ter-ahertz pulses.
作者机构:
[Shao Lin CHEN] College of Mathematics and Statistics,Hengyang Normal University,Hengyang 421002,P.R.China;[Shao Lin CHEN] Hunan Provincial Key Laboratory of Intelligent Information Processing and Application,Hengyang 421002,P.R.China;Department of Mathematics,Indian Institute of Technology Madras,Chennai-600 036,India;[Saminathan PONNUSAMY] 马德拉斯理工学院
通讯机构:
[Shao Lin Chen] C;College of Mathematics and Statistics, Hengyang Normal University, Hengyang, P. R. China<&wdkj&>Hunan Provincial Key Laboratory of Intelligent Information Processing and Application, Hengyang, P. R. China
关键词:
Harmonic K-quasiconformal mapping;Koebe type covering theorem;Koebe type distortion theorem;Radial John disk
作者机构:
[Tan, Yanliang; Lin, Fen; Hu, Tao; Yuan, Hongzhi; Mo, Yixiang; Fan, Zhongkai] Hengyang Normal Univ, Coll Phys & Elect Engn, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.;[Xie, Lin] Hengyang Normal Univ, Coll Math & Stat, Huangbai Rd 165, Hengyang 421008, Hunan, Peoples R China.
通讯机构:
[Yanliang Tan] C;College of Physics and Electronic Engineering , Hengyang Normal University, Huangbai Road 165#, Hengyang, Hunan Province 421008 , China
摘要:
As Rn-222 decays, an alpha particle is emitted and the residual polonium nucleus recoils in the opposite direction. At the end of the recoil path, 88% of the polonium atoms have a positive charge and 12% are neutral. The electric potential distribution in the 60 ml hemispherical internal cell of the radon monitor based on electrostatic collection is studied for reducing the combined probability of the positively charged Po-218 and the OH− produced by the ionization of water vapour in the air. The COMSOL software is used to simulate the electric potential distribution in the internal cell of the radon monitor based on the electrostatic collection method at 27°C, a pressure of 0.1 Mpa. For improving the collection efficiency of Po-218 ions, the average collection time along vertical and oblique lines is calculated when the upper surface of the internal cell is plastic, uncharged metal and charged metal, respectively. Assuming that the gas in the internal cell is uniformly distributed, the results show that if the upper surface of the hemispherical internal cell is plastic or uncharged metal, the electric potential formed in the internal cell is more uniform, and it is beneficial to reduce the total collection time of the positively charged Po-218 ions, thereby improving collection efficiency. The simulation results can be used as an effective reference for optimizing the design of the internal cell structure of the radon monitor based on electrostatic collection method.
通讯机构:
[Qing-Xia Ge; Wen-Jin Yin] S;School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China<&wdkj&>School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China<&wdkj&>Key Laboratory of Intelligent Sensors and Advanced Sensing Materials of Hunan Province, Hunan University of Science and Technology, Xiangtan 411201, China
摘要:
Designing photocatalysts with suitable band alignment and considerable carrier mobility is extremely important. Here, by means of first-principles calculation, we systematically investigated the structural, photoelectronic, and carrier mobility behavior of the two-dimensional Janus MoSSe/WSSe superlattice. The results show that both armchair-type (AN-SL) and zigzag-type (ZN-SL) superlattices are relatively stable with negative Ef values in the range of −2.35 to −1.16 eV. Band gap and band edge position calculations demonstrate that these superlattices are completely suitable for water splitting by visible light. Particularly, the interface contact of the superlattice can be spontaneously changed from type-I to type-II when N > 4, facilitating separation of photogenerated carriers. Furthermore, the hole carrier mobility (μh) in AN-SL can be effectively regulated from 1200 to 2200 cm2 V−1 s−1, much larger than that of the isolated components. Interestingly, the disparity of hole/electron carrier mobility is remarkably large with an approximately 20-fold difference, showing the potential in prohibiting the recombination of photogenerated carriers. This unique behavior is further illustrated by the relaxation times of carriers, where the lifetime of hole carriers is about 7 times larger than that of electron carriers. These findings suggest that forming a Janus superlattice is a promising approach for regulating the photoelectronic properties of semiconductors, providing a promising way to design high efficiency photocatalysts.