检索结果-南通市图书馆

Chinese Journal of Chemical Engineering 2018年第1期26卷 81-88页

作者： Wenjuan Qiu Kang Dou Ying Zhou Haifeng Huang Yinfei Chen Hanfeng Lu College of Environment Zhejiang University of Technology College of Chemical Engineering Zhejiang University of Technology

An activated carbon pore-expanding technique was achieved through innovative reactivation by CO_2/*** original and modified activated carbons were characterized by nitrogen adsorption–desorption,scanning electron microscopy,transmission electron microcopy,and Fourier transform infrared *** mesopore volume increased from 0.122 cm^3·g^(-1) to 0.270 cm^3·g^(-1),and a hierarchical pore structure was formed.A gradual decrease in the phenolic hydroxyl and carboxyl groups on the surface of activated carbon enhanced the surface inertia of granular activated carbon(GAC).The toluene desorption rate of the modified sample increased by 8.81% compared with that of the original *** isotherm fittings revealed that the Langmuir model was applicable for the original and modified activated *** isosteric adsorption heat of toluene on the activated carbon decreased by approximately 50%,which endowed the modified sample with excellent stability in *** modified samples showed an enhanced desorption performance of toluene,thereby opening a way to extend the cycle life and improve the economic performance of carbon adsorbent in practical engineering applications.

关键词： Activated carbon CO2/microwave Pore regulation volatile organic compounds Desorption

AHT Bézier Curves and NUAHT B-Spline Curves

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2007年第4期22卷 597-607页

作者：徐岗汪国昭 Institute of Computer Graphics and Image Processing Zhejiang University Department of Mathematics Zhejiang University

In this paper, we present two new unified mathematics models of conics and polynomial curves, called algebraic hyperbolic trigonometric （ AHT） Bezier curves and non-uniform algebraic hyperbolic trigonometric （ NUAHT） B-spline curves of order n, which are generated over the space span{sin t, cos t, sinh t, cosh t, 1, t,..., t^n-5}, n 7〉 5. The two kinds of curves share most of the properties as those of the Bezier curves and B-spline curves in polynomial space. In particular, they can represent exactly some remarkable transcendental curves such as the helix, the cycloid and the catenary. The subdivision formulae of these new kinds of curves are also given. The generations of the tensor product surfaces are straightforward. Using the new mathematics models, we present the control mesh representations of two classes of minimal surfaces.

关键词： CAD/CAM AHT Bezier curve NUAHT B-spline curves transcendental curves

Thermal Quantum Discord in Anisotropic Heisenberg XXZ Model with Dzyaloshinskii-Moriya Interaction

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2010年第7期54卷 60-66页

作者：陈一新尹志 zhejiang Insitute of Modern Physics Zhejiang University

The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.

关键词： thermal quantum discord Heisenberg XXZ model Dzyaloshinskii-Moriya interaction

Opinion evolution based on cellular automata rules in small world networks

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第3期19卷 584-590页

作者：石晓明施伦张解放 Institute of Nonlinear Physics Zhejiang Normal University Department of Mathematics Zhejiang Normal University

In this paper, we apply cellular automata rules, which can be given by a truth table, to human memory. We design each memory as a tracking survey mode that keeps the most recent three opinions. Each cellular automata rule, as a personal mechanism, gives the final ruling in one time period based on the data stored in one＇s memory. The key focus of the paper is to research the evolution of people＇s attitudes to the same question. Based on a great deal of empirical observations from computer simulations, all the rules can be classified into 20 groups. We highlight the fact that the phenomenon shown by some rules belonging to the same group will be altered within several steps by other rules in different groups. It is truly amazing that, compared with the last hundreds of presidential voting in America, the eras of important events in America＇s history coincide with the simulation results obtained by our model.

关键词： cellular automata rules truth table memory simulation

Black Hole Hair in Higher Dimensions

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2010年第2期53卷 285-290页

作者：曹超陈一新李剑龙 zhejiang Institute of Modern Physics Zhejiang University

We study the property of matter in equilibrium with a static, spherically symmetric black hole in D- dimensional spacetime. It requires that this kind of matter has an equation of state ω≡pr/ρ = -n/（n ＋ 2k）, k, n ∈ N （where n 〉 1 corresponds to a mixture of vacuum matter and ＂hair＂ matter）, which seems to be independent of D. However, when we associate this result with specific models, we find that these hairy black holes can live only in some special dimensional spacetime：（i） D = 2 ＋ 2k/n while the black hole is surrounded by cosmic strings, which requires D is even or D ∈ N, depending on the value of n, this is consistent with some important results in superstring theory, it might reveal the relation between cosmic string and superstring in another aspect; （ii） the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D = 4 is special. We also present some examples of such hairy black holes in higher dimensions, including a toy model with negative energy density.

关键词： black holes extra dimensions cosmic strings

Full-duplex two-way AF relaying systems with imperfect interference cancellation in Nakagami-m fading channels

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第8期64卷 143-155页

作者： Jianping TONG Caijun ZHONG College of Science Zhejiang University of Technology Department of Information and Communication Engineering Zhejiang University

Full-duplex(FD) two-way relaying has the potential to substantially improve the spectral efficiency of the system, and is regarded as an enabling technology for the next generation wireless communication systems. Nevertheless, the joint effect of residual interference and channel fading condition on the fundamental performance of FD two-way relaying systems remains unclear. Motivated by this, this study considers a general FD two-way amplify-and-forward(AF) relaying system with imperfect interference cancellation in the versatile Nakagami-m fading channels, and presents a detailed analytical investigation on the outage performance of the system. The findings of the paper suggest that the performance of the FD two-way AF relaying system depends heavily on the residual interference strength, fading condition parameter m, and signal-to-noise ratio(SNR). The FD scheme outperforms the half-duplex(HD) two-way relaying counterpart in the low and moderate SNR regime, while becomes inferior in the high SNR regime, owing to strong residual interference. Also, compared to the channel fading condition of the information transmission channels, the impact of the channel fading condition of the interference channel on the system performance is relatively insignificant. Moreover, it is desirable to deploy the FD scheme when the channel fading condition of the information transmission channels is good, since it can effectively alleviate the detrimental effect of residual interference.

关键词： full-duplex two-way relaying Nakagami-m fading outage probability sum throughput

同方期刊数据库

A Novel Disturbance Observer Based Fixed-Time Sliding Mode Control for Robotic Manipulators With Global Fast Convergence

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 661-672页

作者： Dan Zhang Jiabin Hu Jun Cheng Zheng-Guang Wu Huaicheng Yan IEEE zhejiang university of Technology Guangxi Normal university zhejiang university the East China university of Science and Technology

This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic ***,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator *** an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not ***,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the *** on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed *** settling time is independent of the initial state of the *** addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov ***,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are *** comparative results confirm that the FTNFTSMC has superior control performance.

关键词： Disturbance observer(DO) fixed-time non-singular sliding mode control robotic manipulator trajectory tracking

Electrode characteristics of non-stoichiometric Ml(NiMnAlFe)_x alloys

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2001年第2期11卷 183-187页

作者：张书凯 LEI Yong-quan 雷永泉陈立新舒康颖张耀王启东吕光烈 Department of Materials Science and Engineering Zhejiang University Central Laboratory Zhejiang University

The phase structure and electrochemical properties of Co free Ml(Ni 0.82 Mn 0.07 Al 0.06 Fe 0.05 ) x alloys with stoichiometry 4.6≤ x ≤5.6 were investigated. The results revealed that most of the as cast non stoichiometric alloys have the main CaCu 5 type structure with a small amount of La 2Ni 7 and LaNi or AlNi secondary phase, the alloys all have typical dendrite structure, the lattice parameter of the alloys increases with the decrease of stoichiometry. Electrochemical measurements showed that the stoichiometric alloy AB 5.0 (the Ml(Ni 0.82 Mn 0.07 Al 0.06 Fe 0.05 ) x alloy with x =5.0) has the highest discharge capacity (310 mAh·g -1 ), and the over stoichiometric alloys have relatively higher cycling stability and high rate dischargeability than others although their maximum discharge capacities are relatively lower compared with the AB 5.0 alloy.

关键词： hydrogen storage alloys non stoichiometry phase structure electrochemical properties

A power conversion system for PMSG-based WECS operating with fully-controlled current-source converters

在线全文

学校读者我要写书评

暂无评论

Journal of zhejiang university-Science C(Computers and Electronics) 2014年第3期15卷 232-240页

作者： Jian-yu BAO Wei-bing BAO Yu-ling LI Ningbo Institute of Technology Zhejiang University Zhijiang College Zhejiang University of Technology College of Electrical Engineering Zhejiang University

We propose a new power conversion system for a permanent magnet synchronous generator(PMSG) based grid-connected wind energy conversion system(WECS) operating with fully-controlled back-to-back current-source converters. On the generator side, two independent current-source rectifiers(CSRs) with space-vector pulse width modulation(SVPWM) are employed to regulate and stabilize DC-link currents. Between DC-link and the electrical grid, a direct-type three-phase five-level current-source inverter(CSI) is inserted as a buffer to regulate real and reactive power fed to the grid and thus adjusts the grid side power-factor. We also present a current-based maximum power point tracking(MPPT) scheme, which helps the generator extract the maximum power through closed-loop regulation of the generator speed. By applying the multilevel modulation and control strategies to the grid-side five-level CSI, a multilevel output current waveform with less distortion is produced, and the bulk requirement of the output capacitor filter to eliminate the harmonic current is reduced. All the proposed concepts are verified by simulation models built in a PSIM environment.

关键词： Grid-connected Wind energy conversion Current-source rectifier Multilevel current-source inverter

Asymptotic behavior of the Taylor-expansion method of moments for solving a coagulation equation for Brownian particles

在线全文

学校读者我要写书评

暂无评论

Particuology 2014年第3期12卷 124-129页

作者： Zhongli Chen Jianzhong Lin Mingzhou Yu zhejiang university China Jiliang university

The evolution equations of moments for the Brownian coagulation of nanoparticles in both continuum and free molecule regimes are analytically studied. These equations are derived using a Taylor-expansion technique. The self-preserving size distribution is investigated using a newly defined dimensionless parameter, and the asymptotic values for this parameter are theoretically determined. The dimensionless time required for an initial size distribution to achieve self-preservation is also derived in both regimes. Once the size distribution becomes self-preserving, the time evolution of the zeroth and second moments can be theoretically obtained, and it is found that the second moment varies linearly with time in the continuum regime. Equivalent equations, rather than the original ones from which they are derived, can be employed to improve the accuracy of the results and reduce the computational cost for Brownian coagulation in the continuum regime as well as the free molecule regime.

关键词： Brownian particles Coagulation Size distribution Accuracy