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Strong Approximations for a Kumar-Seidman Network under a Priority Service Discipline

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Acta Mathematicae Applicatae Sinica 2010年第4期26卷 587-596页

作者： Lin Wu Chuan-xi zhu Yun-jiang Wu Department of Mathematics Nanchang UniversityNanchang330031China Department of Mathematics Xi'an Jiao Tong UniversityXi'anChina

In this paper,we derive the strong approximations for a four-class two station multi-class queuing network（Kumar-Seidman network） under a priority service *** a group,jobs are served in the order of arrival,that is,a first-in-first-out disciple,and among groups,jobs are served under a pre-emptiveresume priority *** show that if the input data（i.e.,the arrival and service processe） satisfy an approximation（such as the functional law-of-iterated logarithm approximation or the strong approximation）,the output data（the departure processes） and the performance measures（such as the queue length,the work load and the sojourn time process） satisfy a similar approximation.

关键词： Strong approximation diffusion approximation priority service discipline Kumar-Seidman network

Elastic Modulus of Fe72.5Ga27.5 Magnetostrictive Alloy

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Chinese Physics Letters 2010年第6期27卷 213-216页

作者： zhu xiao-xi LIU Jing-Hua JIANG Cheng-Bao School of Materials Science and Engineering Beihang University Beijing 100083

The elastic modulus of Fe72.5Ga27.5 magnetostrictive alloy is determined by testing ac impedance resonance frequency and first-principle calculations. The observed elastic modulus is 90.2 GPa for a directionally solidified sample and 103.4 GPa for a water-quenched sample tested in a dc magnetic field of 32. 7mT without compressive pre-stress. The bulk modulus by first-principles calculation is 179.3GPa which is basically consistent with the experimental result. The elastic modulus first increases and then decreases with increasing dc magnetic field, attributed to magnetostriction occurrence in the Fe72.5Ga27.5 alloy. The elastic modulus increases with increasing compressive pre-stress, resulting from the initial magnetic states change under the applied compressive pre-stress. The elastic modulus increases match well with the improved magnetostriction after quenching.

关键词： Elasticity Testing Testes Computers Alloys Magnetic field Sampling Fields District of Columbia Pressing

BENDING OF ORTHOTROPIC SANDWICH PLATES WITH A FUNCTIONALLY GRADED CORE SUBJECTED TO DISTRIBUTED LOADINGS

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Acta Mechanica Solida Sinica 2013年第3期26卷 292-301页

作者： Huadong Li xi zhu Zhiyuan Mei Jiabo Qiu Yingjun Zhang College of Naval Architecture and Power Naval University of Engineering

Based on the Reissner assumptions, this paper is concerned with the bending analy- sis of simply supported sandwich plates with functionally graded core and orthotropic face sheets subjected to transverse distributed loadings. First, the expressions of the displacements, stresses and internal forces of the sandwich plate are presented according to the constitutive relations and stress states of the core and face sheets. Then, the solutions of bending equilibrium equa- tions are derived by expanding the deflection w, transverse shearing forces Q~ and Qv with double trigonometric series that satisfy the simply supported boundary conditions. Finally, the proposed solution is validated by comparing the results with available elasticity solutions for a square sand- wich plate with an isotropie core and finite element simulations for one with functionally graded core. The Young＇s modulus of the functionally graded core is assumed to be graded by a power law distribution of volume fractions of the constituents, and the Poisson＇s ratio is held constant. And the effects of the core＇s top-bottom Young＇s modulus ratio A and volume fraction exponent no on the variation of the displacements of the functionally graded sandwich plate are also examined.

关键词： functionally graded materials orthotropic sandwich plate distributed loading,simply supported

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空域色噪声下的多输入多输出雷达角度估计

科学技术与工程 2024年第14期24卷 5855-5862页

作者：陈金立唐熠君朱熙铖李家强南京信息工程大学电子与信息工程学院南京210044

由于多输入多输出(multiple input multiple output,MIMO)雷达的空域色噪声协方差矩阵通常为非对角矩阵,因此在色噪声下信号子空间与噪声子空间无法有效分离,从而致使传统算法无法有效估计目标角度。为此,首先利用信号协方差矩阵的低秩... 详细信息

由于多输入多输出(multiple input multiple output,MIMO)雷达的空域色噪声协方差矩阵通常为非对角矩阵,因此在色噪声下信号子空间与噪声子空间无法有效分离,从而致使传统算法无法有效估计目标角度。为此,首先利用信号协方差矩阵的低秩性和色噪声协方差矩阵的稀疏性来抑制空域色噪声。然后,根据MIMO雷达数据的内在多维结构特性,建立四阶张量CP(canonical or parallel factor analysis,CANDECOMP/PARAFAC)分解模型。针对传统交替最小二乘算法对数值病态性较为敏感而导致CP分解精度低的问题,利用张量因子矩阵之间的共轭关系来降低求解的病态敏感度,提高张量分解的稳健性。最后,利用最小二乘拟合法从因子矩阵的估计值中得到目标角度。仿真结果表明,所提算法能够对色噪声有效抑制并提高了角度估计的精度。

关键词：空域色噪声 MIMO雷达低秩和稀疏分解张量分解角度估计

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环γ-聚谷氨酸的制备及美白活性研究

食品与药品 2024年第1期26卷 49-56页

作者：王梦灿朱希强林剑山东丰金生物医药有限公司山东烟台264100 烟台大学生命科学学院山东烟台264005

目的制备环γ-聚谷氨酸,研究其美白活性。方法以谷氨酸(Fmoc-Glu-OTBU)为原料,制备四元、八元和十元的环γ-聚谷氨酸(cyclo-γ-PGA),通过体外和细胞内实验,研究3种不同相对分子质量(M_(r))的cyclo-γ-PGA的酪氨酸酶抑制活性。结果测... 详细信息

目的制备环γ-聚谷氨酸,研究其美白活性。方法以谷氨酸(Fmoc-Glu-OTBU)为原料,制备四元、八元和十元的环γ-聚谷氨酸(cyclo-γ-PGA),通过体外和细胞内实验,研究3种不同相对分子质量(M_(r))的cyclo-γ-PGA的酪氨酸酶抑制活性。结果测得3种产物四元cyclo-γ-PGA、八元cyclo-γ-PGA和十元cyclo-γ-PGA纯度分别为98.31%,95.29%,95.67%,M_(r)分别为516.39,1032.83,1291.28。以γ-PGA为对照品,3种不同M_(r)的cyclo-γ-PGA均具有不同程度的酪氨酸酶抑制活性,其中十元cyclo-γ-PGA酪氨酸酶活性在体外和细胞内均最强。结论 cyclo-γ-PGA具有美白活性,美白活性随着M_(r)的增大而增加,且在细胞内的特性表现更优异;cyclo-γ-PGA的美白活性要高于γ-PGA,为后续cyclo-γ-PGA用于皮肤美白和化妆品领域中提供理论基础。

关键词：环γ-聚谷氨酸美白活性酪氨酸酶抑制小鼠黑色素瘤细胞

Optimal power allocation for two-way relaying over OFDM using physical-layer network coding

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The Journal of China Universities of Posts and Telecommunications 2011年第1期18卷 9-15,35页

作者： LI Fu-nian zhu Guang-xi WANG De-sheng Department of Electronic and Information Engineering Huazhong University of Science and Technology Wuhan 430074 China Department of Electronic and Information Engineering Wuhan University of Science and Technology Wuhan 430081 China

In this paper, a network scenario of two-way relaying over orthogonal frequency division multiplexing （OFDM） is considered, in which two nodes intend to exchange the information via a relay using physical-layer network coding （PLNC）. Assuming that the full channel knowledge is available, an optimization problem, which maximizes the achievable sum rate under a sum-power constraint, is investigated. It is shown that the optimization problem is non-convex, which is difficult to find the global optimum solution in terms of the computational complexity. In consequence, a low-complexity optimal power allocation scheme is proposed for practice implementation. A link capacity diagram is first employed for power allocation on each subcarrier. Subsequently, an equivalent relaxed optimization problem and Karush-Kuhn-Tucker （KKT） conditions are developed for power allocation among each subcarrier. Simulation results demonstrate that the substantial capacity gains are achieved by implementing the proposed schemes efficiently with a low-complexity computational effort.

关键词： two-way relaying power allocation physical-layer network coding OFDM

Metalorganic Chemical Vapor Deposition of GaAs on Si Substrate Prepared by Room Temperature Chemical Cleaning Treatment

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Chinese Physics Letters 1997年第9期14卷 690-693页

作者： YIN Min LOU Li-ren FU zhu-xi Structure Research Laboratory University of Science and Technology of China and Chinese Academy of SciencesHefei 230026 Department of Physics University of Science and Technology of ChinaHefei 230026

A new method for metalorganic chemical vapor deposition(MOCVD)of GaAs on Si substrates is *** of the usual high temperature surface cleaning treatment for Si substrate,the new method uses room temperature HF vapor polishing in the preparation chamber in the MOCVD system as the first step of the *** crystal GaAs layers with mirror-like surfaces were obtained.

关键词： MOCVD polishing mirror

Study on discharge characteristics and improving surface hydrophobicity of epoxy resin by nanosecond pulse excited argon/hexamethyldisiloxane jet array

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High Voltage 2022年第4期7卷 771-781页

作者： Zhiyan Liu Jingang Xu xi zhu Feng Liu Zhi Fang College of Electrical Engineering and Control Science Nanjing Tech UniversityNanjingChina

Surface flashover of insulating materials induced by pollution and moisture environment is one of the main reasons for the damage of power system and electrical *** improvement of the insulating materials surface hydrophobicity is key important,which can prevent the pollutants and water attachment,and enhance the insulating *** this paper,the super-hydrophobic film is formed on the surface of epoxy resin by a one-dimensional(1D)argon(Ar)jet array driven by nanosecond pulse power supply with hexamethyldisiloxane(HMDSO)*** influences of the processing time and HMDSO content on the epoxy resin surface hydrophobicity are *** shows that with 0.04%HMDSO,the jet array achieves a best hydrophobic treatment effect on the epoxy resin *** 60 s treatment,the apparent contact angle(ACA)of the epoxy resin surface increases from 60.3°of the untreated surface to 150.0°.The wettability of epoxy resin surface does not change too much as the treatment time beyond 60 *** maximum ACA value 153.4°appears at 120 s processing time,which is just slightly higher than that of 60 s treatment *** epoxy resin surface morphology and chemical feature before and after plasma processing are characteristics by the scanning electron microscopy(SEM),atomic force microscopy(AFM),Fourier transform infra-red spectroscopy and X-ray photoelectron *** shows that the treated epoxy resin surface is covered with dense coral like particles in nanoscales,the original C=O、C-H and other organic functional groups are replaced by Si-(CH3),Si-O-Si and other silicon containing groups,and the Si content increases from 0.4%to 28.0%.The experimental results provide important references to develop jet array as an efficient tool to enhance the surface hydrophobicity and insulating performance of insulating materials.

关键词： resin surface characteristics

UAV navigation in high dynamic environments:A deep reinforcement learning approach

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Chinese Journal of Aeronautics 2021年第2期34卷 479-489页

作者： Tong GUO Nan JIANG Biyue LI xi zhu Ya WANG Wenbo DU School of Electronic and Information Engineering Beihang UniversityBejing 100083China Key Laboratory of Advanced Technology of Near Space Information System(Beihang University) Ministry of Industry and Information Technology of ChinaBeijing 100083China Research Institute of Frontier Science Beihang UniversityBeijing 100083China College of Software Beihang UniversityBeijing 100083China State Key Laboratory of Software Development Environment Beihang UniversityBeijing 100083China

Unmanned Aerial Vehicle(UAV) navigation is aimed at guiding a UAV to the desired destinations along a collision-free and efficient path without human interventions, and it plays a crucial role in autonomous missions in harsh environments. The recently emerging Deep Reinforcement Learning(DRL) methods have shown promise for addressing the UAV navigation problem,but most of these methods cannot converge due to the massive amounts of interactive data when a UAV is navigating in high dynamic environments, where there are numerous obstacles moving *** this work, we propose an improved DRL-based method to tackle these fundamental *** be specific, we develop a distributed DRL framework to decompose the UAV navigation task into two simpler sub-tasks, each of which is solved through the designed Long Short-Term Memory(LSTM) based DRL network by using only part of the interactive data. Furthermore, a clipped DRL loss function is proposed to closely stack the two sub-solutions into one integral for the UAV navigation problem. Extensive simulation results are provided to corroborate the superiority of the proposed method in terms of the convergence and effectiveness compared with those of the state-of-the-art DRL methods.

关键词： Autonomous vehicles Deep learning Motion planning Navigation Reinforcement learning Unmanned Aerial Vehicle(UAV)