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Price-based time and energy allocation in cognitive radio multiple access networks with energy harvesting

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Science China(Information Sciences) 2017年第10期60卷 258-260页

作者： Ding XU qun li Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications

Cognitive radio(CR),a concept that can solve the conflict between spectrum scarcity and low spectrum utilization,has been researched widely recently[1].There are mainly three CR models:interweave,overlay and underlay[... 详细信息

关键词： CBS Price-based time and energy allocation in cognitive radio multiple access networks with energy harvesting

New development of anodizing process of magnesium alloys

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中国有色金属学会会刊：英文版 2004年第z1期14卷 120-125页

作者： BAI li-qun li Di School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

Magnesium alloy, a kind of environment-friendly material with promising and excellent properties, is a good choice for a number of applications. The research and development of anodizing on magnesium alloys and its ap... 详细信息

关键词： magnesium magnesium alloy anodizing

Effective capacity region and power allocation for two-way spectrum sharing cognitive radio networks

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Science China(Information Sciences) 2015年第6期58卷 126-135页

作者： XU Ding li qun Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications School of Computer Science and Technology Nanjing University of Posts and Telecommunications

In this paper, we consider a spectrum sharing cognitive radio(CR) network where a pair of twoway secondary users(SUs) is allowed to coexist with a primary user(PU) as long as the interference power received at the PU is below an acceptable limit. Under the interference power constraint, we investigate the effective capacity region for two-way SUs. In particular, we derive a closed-form solution for the power allocation problem to achieve the boundary points of an inner bound on the effective capacity region. We also propose a key parameter referred to as weighted-transmission-interference-ratio(WTIR), which plays a significant role in the power allocation policy. In the proposed power allocation policy, the exclusive transmission of SUs shall be performed if one SU’s WTIR is much larger than the others. That is, the one with much larger WTIR shall be allocated non-zero power and the other one shall be allocated zero power. Otherwise, if the difference of their WTIRs is not significant, the concurrent transmission shall be performed. That is, both SUs shall be allocated non-zero power. It is shown that a loose interference power constraint leads to the concurrent transmission in most situations, while a stringent interference power constraint leads to the exclusive transmission in most situations. It is also shown that for the stringent interference power constraint and loose delay quality-of-service(Qo S) constraint, the proposed power allocation policy is almost optimal and thus the obtained inner bound on the effective capacity region is tight.

关键词： cognitive radio effective capacity delay quality-of-service power allocation two-way

Cooperative resource allocation in cognitive wireless powered communication networks with energy accumulation and deadline requirements

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Science China(Information Sciences) 2019年第8期62卷 145-158页

作者： Ding XU qun li Wireless Communication Key Lab of Jiangsu Province Nanjing University of Posts and Telecommunications Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks Nanjing University of Posts and Telecommunications

This study investigates a multi-carrier cognitive wireless powered communication network(CWPCN) with a wirelessly powered primary user(PU). A two-stage cooperative protocol between the PU and the secondary user(SU) is adopted so that the PU can harvest energy from the SU while the SU gains transmission opportunities. It is assumed that the energy harvested by the PU can be accumulated for future usage, and the quality of service of the PU is guaranteed by satisfying the required minimum number of data bits for a given deadline. Herein, we maximize the SU rate by considering the time allocation,subcarrier allocation, and power allocation in both an offline setting(in which the future channel gains are known a priori) and an online setting(in which only the current channel gains are known). In the offline and online schemes, the maximization problem is solved using the block-coordinate descent method and the Lagrange duality method. The effectiveness of the proposed schemes is evaluated and verified via simulation experiments against benchmark schemes.

关键词： wireless powered communication networks energy harvesting cognitive radio deadline constraint energy accumulation

Complex dynamics of a harmonically excited structure coupled with a nonlinear energy sink

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Acta Mechanica Sinica 2017年第4期33卷 801-822页

作者： Jian Zang li-qun Chen Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai 200072 China Department of Mechanics Shanghai UniversityShanghai 200444 China

Nonlinear behaviors are investigated for a structure coupled with a nonlinear energy sink. The structure is linear and subject to a harmonic excitation, modeled as a forced single-degree-of-freedom oscillator. The nonlinear energy sink is modeled as an oscillator consisting of a mass,a nonlinear spring, and a linear damper. Based on the numerical solutions, global bifurcation diagrams are presented to reveal the coexistence of periodic and chaotic motions for varying nonlinear energy sink mass and stiffness. Chaos is numerically identified via phase trajectories, power spectra,and Poincaré maps. Amplitude-frequency response curves are predicted by the method of harmonic balance for periodic steady-state responses. Their stabilities are *** Hopf bifurcation and the saddle-node bifurcation are determined. The investigation demonstrates that a nonlinear energy sink may create dynamic complexity.

关键词： bifurcation excited saddle harmonic chaotic oscillator stiffness freedom branches modeled

Approximate and numerical analysis of nonlinear forced vibration of axially moving viscoelastic beams

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Acta Mechanica Sinica 2011年第3期27卷 426-437页

作者： Hu Ding li-qun Chen Shanghai Institute of Applied Mathematics and Mechanics Shanghai University 200072 Shanghai China Department of Mechanics Shanghai University 200436 Shanghai China

Steady-state periodical response is investigated for an axially moving viscoelastic beam with hybrid supports via approximate analysis with numerical confirmation. It is assumed that the excitation is spatially uniform and temporally harmonic. The transverse motion of axially moving beams is governed by a nonlinear partial-differential equation and a nonlinear integro-partial-differential equation. The material time derivative is used in the viscoelastic constitutive relation. The method of multiple scales is applied to the governing equations to investigate primary resonances under general boundary conditions. It is demonstrated that the mode uninvolved in the resonance has no effect on the steady-state response. Numerical examples are presented to demonstrate the effects of the boundary constraint stiffness on the amplitude and the stability of the steady-state response. The results derived for two governing equations are qualitatively the same,but quantitatively different. The differential quadrature schemes are developed to verify those results via the method of multiple scales.

关键词： Axially moving beam. Nonlinearity . Mate-rial time derivative . Method of multiple scales. Differentialquadrature method

An ontological metamodeling framework for semantic simulation model engineering

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Journal of Systems Engineering and Electronics 2020年第3期31卷 527-538页

作者： LEI Yonglin ZHU Zhi li qun School of Systems Engineering National University of Defense TechnologyChangsha 410073China

Recently,the ontological metamodel plays an increasingly important role to specify systems in two forms:ontology and *** is a descriptive model representing reality by a set of concepts,their interrelations,and *** the other hand,metamodel is a more classical,but more powerful model in which concepts and relationships are represented in a prescriptive *** study firstly clarifies the difference between the two approaches,then explains their advantages and limitations,and attempts to explore a general ontological metamodeling framework by integrating each characteristic,in order to implement semantic simulation model *** a proof of concept,this paper takes the combat effectiveness simulation systems as a motivating case,uses the proposed framework to define a set of ontological composable modeling frameworks,and presents an underwater targets search scenario for running simulations and analyzing ***,this paper expects that this framework will be generally used in other fields.

关键词： ontology metamodeling semantic composability model-driven engineering(MDE)

Coupling electro-mechanical behaviors in the interdigital electrode device of ferroelectrics

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Acta Mechanica Sinica 2021年第4期37卷 649-661,I0003页

作者： Suxin Pan Shilin Xie qun li State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China

The electro-mechanical coupling behaviors of ferroelectric devices with interdigital electrodes may become complicated due to the material inhomogeneity and local field concentration under the complex working *** this paper,a ferroelectric model,drawn from the typical interdigital electrode structure of a ferroelectric sensor,is established based on phase field theory,to study the polarization evolution and explore the evolution laws in *** results show that there appears ferroelectric creep even under an applied electric field below the coercive field ***,the configurational force theory is introduced to investigate the mechanical behaviors related to polarization switching in the ferroelectric samples with interdigital *** is found that configurational force and polarization have similar evolution laws in both time evolving and space *** considering the configurational force as the driving force,it is possible to predict the potential direction of polarization evolution and explore its evolution mechanism in ferroelectrics,demonstrating the configurational force as a useful parameter for describing mechanical behavior during the polarization evolution and a powerful tool for investigating the evolution mechanism of microstructure with coupling effects in ferroelectric materials.

关键词： Phase field modeling Configurational force Polarization evolution Domain switching Interdigital electrode

Support Vector Machine active learning for 3D model retrieval

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1953-1961页

作者： LENG Biao QIN Zheng li li-qun Department of Computer Science and Technology Tsinghua University Beijing 100084 China School of Software Tsinghua University Beijing 100084 China

In this paper, we present a novel Support Vector Machine active learning algorithm for effective 3D model retrieval using the concept of relevance feedback. The proposed method learns from the most informative objects which are marked by the user, and then creates a boundary separating the relevant models from irrelevant ones. What it needs is only a small number of 3D models labelled by the user. It can grasp the user＇s semantic knowledge rapidly and accurately. Experimental results showed that the proposed algorithm significantly improves the retrieval effectiveness. Compared with four state-of-the-art query refinement schemes for 3D model retrieval, it provides superior retrieval performance after no more than two rounds of relevance feedback.

关键词： 3D model retrieval Shape descriptor Relevance feedback Support Vector Machine (SVM) Active learning