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Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

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Chinese Chemical Letters 2009年第12期20卷 1498-1501页

作者： zhen zhen Hu Ying Ying zhong Yun Chang Fan Yan Zhu Department of Chemistry Xixi Campus Zhejiang University Hangzhou 310028 China

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

关键词： Inorganic anions Ethyl acetate In-line hollow fiber membrane extraction Ion chromatography

Green Circuit Design for Battery-Free Sensors in Cloud Radio Access Network

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China Communications 2015年第11期12卷 1-11页

作者： ZENG Tengchan MA zhen WANG Gongpu zhong Zhangdui School of Electronic and Information Engineering Beijing Jiaotong University School of Computer and Information Technology Beijing Jiaotong University

Cloud radio access network(C-RAN)is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. Currently,most sensors need batteries for power,which is energy-consuming and maintenance-heavy. To further improve energy effi ciency(EE) of sensors in C-RAN,this paper proposes a new structure as well as practical circuit design for green sensors in C-RAN. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads(RRHs) and user terminals(UTs). To demonstrate the validity of the new structure,a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically,selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition,two methods to stabilize the output voltage are proposed and analyzed. Finally,simulation results as well as experimental results are provided to corroborate our proposed studies.

关键词： energy harvesting C-RAN batteryfree sensor energy eff iciency

An Efficient and Practical Public Key Cryptosystem with CCA-Security on Standard Model

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Tsinghua Science and Technology 2014年第5期19卷 486-495页

作者： zhen Liu Xiaoyuan Yang Weidong zhong Yiliang Han Department of Network and Information Security Key Laboratory Engineering University of the Armed PoliceForce

Chosen Ciphertext Attack （CCA） security on the standard model is widely accepted as the standard security notion for the public key cryptosystem. The existing CCA-secure public key cryptosystems on the standard model are expensive in terms of efficiency and practicality. In this paper, an efficient and practical public key cryptosystem is presented over the group of signed quadratic residues. It is provably secure against CCA on the standard model. Furthermore, public verifiability for this scheme is also realized in the way that projects the verification privacy key into public key on trapdoor pretending. It will be useful to devise efficient CCA-secure threshold and proxy re-encryption schemes on the standard model.

关键词： public key cryptosystem standard model Chosen Ciphertext Attack (CCA)-security public verifiability

Effect of organophosphorus pesticide pollution on soil animals

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Journal of Environmental Sciences 2000年第1期12卷 49-58页

作者： Wang, zhen-zhong Zhang, You-Mei Guo, Yong-Can Li, zhong-Wu Resource and Environment Department Hunan Normal University Changsha 410081 China

This paper studied the change in soil animal community in contaminated and irrigated area by organophosphorus pesticide waste water and its mechanism was discussed. The results showed that the species and quantities of soil animals decreased with organophosphorus pesticide pollution degree increasing. The species of soil animals decreased with average and rare population mainly decreasing, while the amount change was associated with that of the dominant population of Acarina, Collembola and Nematoda. Toxicity experiment demonstrated that the respiration intensity of soil animal was restrained obviously by pesticide pollution. After observation of SEM, the effect of pesticide pollution on the earthworm (\%Pheretima robusta)\% stomach intestinal mucosa damage has been observed, which showed the pesticide contamination may damage the earthworms bodies. Ulcerous focus and perforation on stomach mucosa were usually seen. The stomach microvilli appeared atrophic and disordered especially in the bodies of these earthworms growing in seriously polluted soil, bad atrophic phenomena were seen not only on the stomach mucosa microvilli but also on the cilia of the intestinal mucosa which appeared swollen as a spheroid. Under TEM, RER and Golgi compound dilatation, chondrisome swell and ridge disappearance were observed on cells of stomach epithelium mucosa of \%***\% collected from heavy polluted area. By calculation, the safety concentration of earthworm in methamidophos pesticide is 0\^2517 ml/L.

关键词： pesticide pollution soil animal respiration intensity pathological changes LC 50 CLC number: X592 Document code: A

Quantum connectivity optimization algorithms for entanglement source deployment in a quantum multi-hop network

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Frontiers of physics 2018年第2期13卷 1-12页

作者： zhen-zhen Zou xu-Tao Yu Zai-Chen Zhang State Key Laboratory of Millimeter Waves Southeast University Nanjing 210096 China National Mobile Communications Research Lab Southeast University Nanjing 210096 China

At first, the entanglement source deployment problem is studied in a quantum multi-hop network, which has a significant influence on quantum connectivity. Two optimization algorithms are introduced with limited entanglement sources in this paper. A deployment algorithm based on node position （DNP） improves connectivity by guaranteeing that all overlapping areas of the distribution ranges of the entanglement sources contain nodes. In addition, a deployment algorithm based on an improved genetic algorithm （DIGA） is implemented by dividing the region into grids. From the simulation results, DNP and DIGA improve quantum connectivity by 213.73% and 248.83% compared to random deployment, respectively, and the latter performs better in terms of connectivity. However, DNP is more flexible and adaptive to change, as it stops running when all nodes are covered.

关键词： entanglement source deployment quantum connectivity deployment algorithm

A review of space-object collision probability computation methods

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Astrodynamics 2022年第2期6卷 95-120页

作者： Jia-Sheng Li zhen Yang Ya-zhong Luo College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China Hunan Key Laboratory of Intelligent Planning and Simulation for Aerospace Missions Changsha 410073China

The collision probability computation of space objects plays an important role in space situational awareness,particularly for conjunction assessment and collision *** works mainly relied on Monte Carlo simulations to predict collision *** such simulations are accurate when a large number of samples are used,these methods are perceived as computationally intensive,which limits their application in *** overcome this limitation,many approximation methods have been developed over the past three *** paper presents a comprehensive review of existing space-object collision probability computation *** advantages and limitations of different methods are analyzed and a systematic comparison is *** regarding how to select a suitable method for different short-term encounter scenarios is then ***,potential future research avenues are discussed.

关键词： collision probability space situational awareness collision avoidance astrodynamics

Towards Qo E-based resource allocation schemes in SC-FDMA systems

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The Journal of China Universities of Posts and Telecommunications 2015年第5期22卷 63-70 100,100页

作者： Hu Yahui Liu Yinlong Zhou xu xu zhen Institute of Information Engineering Chinese Academy of Science

One of the critical techniques of quality of experience(Qo E) provisioning in single carrier frequency division multiple access(SC-FDMA) systems is related to implementation of efficient radio resource allocation(RRA) schemes. So far as we know, Qo E-based RRA in SC-FDMA systems is still an open issue. Therefore, in this paper, five different Qo E-based RRA schemes in SC-FDMA system are investigated based on different criteria. The first three Qo E criteria applied in other wireless systems are maximizing average mean opinion score(MOS) over all users(Max-MOS), maximizing the minimum MOS among all users(Max Min-MOS) and maximizing the minimum MOS with dropping some users requiring the highest amount of resources(Max Min-Min MOSX.Y-MOS). Then, the improved Max Min-Min MOSX.Y-MOS criterion focuses on changing user dropping principle to promote the probability of more users obtaining satisfied experience. By defining MOS higher than threshold as the effective MOS, maximizing average effective MOS over all users(Max-EMOS) is proposed as a totally new criterion which gives quantitative measurement of how many users to what extent obtaining satisfied experience. Mathematical expressions and solutions of these schemes are also presented in this paper. In addition, performance comparisons are made in simulations to further display their respective advantages and disadvantages.

关键词： single carrier frequency division multiple access(

Rate Function of Large Deviation for a Class of Nonhomogeneous Markov Chains on Supercritical Percolation Network

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Acta Mathematica Sinica,English Series 2011年第9期27卷 1813-1830页

作者： zhong Hao xu Dong HAN School of Finance and Statistics East China Normal University Shanghai 200241 P. R. China Department of Mathematics Shanghai Jiao Tong University Shanghai 200240 P. R. China

We model an epidemic with a class of nonhomogeneous Markov chains on the supercritical percolation network on Zd. The large deviations law for the Markov chain is given. Explicit expression of the rate function for la... 详细信息

关键词： Nonhomogeneous Markov chain large deviation rate function percolation network

Characterization of Pr-CeO_2 Nano-crystallites Prepared by Low-temperature Combustion&Hydrothermal Synthesis

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Chinese Journal of Structural Chemistry 2006年第10期25卷 1270-1274页

作者： ZHU zhen-Feng WANG Bao-Li MA Jian-zhong School of Materials Science and Engineering Shaanxi University of Science ＆ Technology Xianyang 712081 China

Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM, EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr^＋3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr^＋3 substitutes Ce^＋4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.

关键词： low-temperature combustion hydrothermal treatment Pr-CeO2 pigments,nano-crystalline