检索结果-南通市图书馆

Decentralized beamforming design and power allocation for limited coordinated multi-cell network

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2013年第4期20卷 52-58,72页

作者： CUI wen-tao NIU Kai LI nan WU Wei-ling Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications School of Mechanical Electrical and Information Engineering Shandong University at Weihai

Multi-cell processing （MCP） is capable of providing significant performance gain, but this improvement is accompanied by dramatic signaling overhead between cooperative base stations. Therefore, balancing the performance gain and overhead growth is crucial for a practical multi-base cooperation scheme. In this paper, we propose a decentralized algorithm to jointly optimize the power allocation and beamforming vector with the goal of maximizing the system performance under the constraint of limited overhead signal and backhaul link capacity. In particular, combined with calculating the transmission beamforming vector according to the local channel state information, an adaptive power allocation is presented based on the result of sum capacity estimation. Furthermore, by utilizing the concept of cell clustering, the proposed framework can be implemented in a practical cellular system without major modification of network architecture. Simulation results demonstrate that the proposed scheme improves the system performance in terms of the sum capacity and cell-edge capacity.

关键词： MCP co-channel interference adaptive power allocation distributed beamforrning limited capacity backhauling

Robust time reversal focusing based on Maximin criterion in a waveguide with uncertain water depth

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第10期56卷 1822-1832页

作者： PAN xiang WANG nan ZHANG JiangFan XU wen GONG xianYi Department of Information Science and Electronic Engineering Zhejiang University Hangzhou Applied Acoustic Research Institute

Time reversal processing （TRP） might be regarded as matched field processing with known environmental knowledge. However, the performance of TRP is degraded in an uncertain environment. A technique based on the Maximin criterion is pro- posed for enhancing the robustness of TRP in a waveguide with uncertain water depth. The relationship between the water depth and the focal spot translation is examined based on the waveguide-invariant theory. Then the time reversal transmissiou scheme with the Maximin criterion is performed to maximize the minimum transmission power on a target of interest. At the receiving end, coherent summation operation is carried out over the received data by a reception focusing bank. If it is neces- sary to enhance the target echo further, the iterative time reversal can be considered where the target echo corresponding to the first time reversal transmission is regarded as a secondary source. Numerical simulations and experimental results of the target localization in a waveguide tank have verified the effectiveness of robust TRP.

关键词： robustness time reversal processing uncertain water depth waveguide sonar

Bioavailability of cyanide in the different environmental compartments

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第2期18卷 347-352页

作者： YU xiao-zhang LEI Jun-jie XUE nan-dong TANG Ya-wen Department of Environmental Science Hunan Agricultural UniversityChangsha 410128 China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Vascular plants possess an enzyme system that detoxifies cyanide by converting it to the amino acid asparagine. Hybrid willows （Salix matsudana Koidz×Salix alba L.） were exposed to cyanide to determine whether willows can transport and metabolize this compound. Pre-rooted trees were grown in different environmental compartments, spiked or irrigated with potassium cyanide at 24.0±0.5℃. Cyanide in compartments, in air and in tissues of plants was analyzed spectrophotometrically. Results from this study indicated that large amounts of applied cyanide was removed from the systems during the presence of willows. Growing compartments of plants have a strong influence on the removal rates of cyanide. Little or no initial cyanide was detected in plant materials. Volatilization of cyanide was not occurring. Mass balance studies showed that applied cyanide was significantly metabolized during transport through willows cuttings. However, there was a clear difference between the metabolism rates of cyanide by willows exposed to different environmental compartments. The highest cyanide metabolism rate was found at the treatment with willows growing in hydroponic solution with a metabolism rate of 2.44 mgCN/（kg, d）, followed by willows growing in sand with a value of 1.02 mgCN/（kg·d）. The lowest metabolism rate had the willows growing in soils（0.43 mgCN/（kg·d）. In conclusion, transport and metabolism of cyanide in plants is likely and phytoremediation of cyanide is a feasible option for cleaning soils and water contaminated with cyanide.

关键词： cyanide hybrid willows metabolism phytoremediation

Competitive Nucleation and Rapid Growth of Co-Si Intermetallic Compounds during Eutectic Solidification under Containerless Processing Condition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2011年第11期27卷 1077-1082页

作者： wenjing Yao Zipeng Ye nan Wang xiujun Han Jianyuan Wang xixing wen Department of Applied Physics Northwestern Polyteehnical University Xi＇an 710072 China School of Materials Science Shanghai Jiaotong University Shanghai 200240 China

The liquid-solid transitions of （Co2Si＋CoSi） and （CoSi＋CoSi2） eutectic alloys were realized in drop tube and the rapid eutectic growth mechanism of intermetallic compounds was examined. The experimental and calculated results indicate that with increasing Co content, the intermetallic compound prefers nucleating primarily. The eutectic microstructures experience the transitions of ＇lamellar-anomalous-divorced＇ eutectic with undercooling. In undercooled state, the growth of CoSi intermetallic compound always lags behind others, and no matter how large the undercooling is, this intermetallic compound grows under the solutal diffusion control The calculated coupled zone demonstrates that （Co2Si＋CoSi） eutectic can form within certain undercooling regime, when the composition is in the range from 23.6% to 25.4% Si. And the calculated coupled zone of （CoSi＋CoSi2） covers a composition range from 40.8% to 43.8% Si.

关键词： Liquid-solid transition Competitive nucleation Intermetallic compound Undercooling

Bifunctional iron-phtalocyanine metal-organic framework catalyst for ORR, OER and rechargeable zinc-air battery

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2020年第7期39卷 815-823页

作者： wen-Zheng Cheng Jia-Lin Liang Heng-Bo Yin Ya-Jin Wang wen-Fu Yan Jia-nan Zhang College of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Inorganic Synthesis and Preparation Jilin UniversityChangchun 130012China

Exploring non-noble metal and high-activity electrocatalysts through a simple and controllable protocol remains a great challenge for oxygen reduction reaction(ORR)and zinc-air ***,we developed a melt polymerization strategy to synthesize iron-polyphthalocyanine(FePPc)metallic-organic frameworks(MOFs)over the carbon black matrix(Fe PPc@CB).Through noncovalentπ-πinteractions,Fe PPc molecules can anchor on carbon matrix,thus facilitating the electron transfer process and stabilizing the *** to abundant free electrons and atomically MN4 catalytic sites in the macrocycle structure,FePPc@CB exhibits excellent oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalytic *** FePPc@CB also delivers excellent performances for liquid and flexible all-solidstate batteries compared to that of commercial Pt/C,making it a promising ORR/OER electrocatalyst.

关键词： Metal-organic frameworks Poly-iron-polyphthalocyanine Oxygen reduction reaction Zn-air battery

MiR-1306-5p对鸡前脂肪细胞增殖与分化的影响

在线全文

学校读者我要写书评

暂无评论

农业生物技术学报 2025年第1期33卷 157-165页

作者：孙楠桢张蕾陈若楠张若彤孙杰石河子大学动物科技学院

miR-1306-5p对肿瘤细胞的增殖具有促进作用，对脂肪细胞增殖与分化的影响尚不明确。课题组前期采集玫瑰冠鸡(Gallus gallus)和科宝鸡胚胎期第8天胸肌组织进行高通量测序，本研究选择测序数据中筛选出的差异表达的miR-1306-5p，旨在探究m... 详细信息

miR-1306-5p对肿瘤细胞的增殖具有促进作用，对脂肪细胞增殖与分化的影响尚不明确。课题组前期采集玫瑰冠鸡(Gallus gallus)和科宝鸡胚胎期第8天胸肌组织进行高通量测序，本研究选择测序数据中筛选出的差异表达的miR-1306-5p，旨在探究miR-1306-5p在鸡前脂肪细胞增殖与分化过程中的功能。利用Targetscan和miRanda软件预测miR-1306-5p的靶基因，以脂肪代谢相关基因—骨形态发生蛋白2(bone morphogenetic protein 2, BMP2)为靶基因构建野生型和突变型载体，与miR-1306-5p模拟物共转染鸡成纤维细胞，利用荧光素酶报告基因检测系统验证二者的靶标关系。以miR-1306-5p模拟物和抑制物分别转染鸡前脂肪细胞，利用CCK-8(Cell Counting Kit-8)试剂盒检测细胞增殖能力，通过油红O染色检测油酸诱导的分化情况。结果显示，BMP2野生型与miR-1306-5p模拟物共转染组的荧光素酶活性较阴性对照极显著下降(P<0.01)，而突变型没有显著变化；miR-1306-5p模拟物转染鸡前脂肪细胞48、72和96h，细胞增殖能力极显著低于阴性对照(P<0.01)；在鸡前脂肪细胞的油酸诱导分化过程中，脂肪酸结合蛋白4(fatty acid binding protein 4, FABP4)基因表达量极显著升高(P<0.01)，而内源性miR-1306-5p和BMP2在诱导分化48和72 h的基因表达量极显著降低(P<0.01)；在鸡前脂肪细胞中转染miR-1306-5p模拟物后脂滴较对照小，转染miR-1306-5p抑制物后脂滴增多。因此，miR-1306-5p可能通过靶向BMP2而抑制鸡前脂肪细胞的分化。本研究为深入探讨miR-1306-5p在鸡前脂肪细胞分化中的作用机制提供基础资料。

关键词：鸡前脂肪细胞 miR-1306-5p 骨形态发生蛋白2(BMP2) 细胞增殖细胞分化

Simulation of maize drought degree in xi'an City based on cusp catastrophe model

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Water Science and Engineering 2021年第1期14卷 28-35页

作者： Hai-tao Chen Ji He wen-chuan Wang xiao-nan Chen School of Water Resources North China University of Water Resources and Electric PowerZhengzhou 450045China Construction and Administration Bureau of South-to-North Water Diversion Middle Route Project Beijing 100038China

Drought generally has significant impacts on *** is essential to quantitatively evaluate the relationship between crop production and drought degree to provide technical support for drought disaster *** this study,a drought degree index that can reflect the changes in precipitation,evapotranspiration,and soil moisture was developed on the basis of crop yield reduction *** drought scenarios were set up to simulate the effects of meteorological drought on drought degree of crops at different growth stages.A cusp catastrophe model was constructed to analyze the mutation characteristics of the drought degree of maize at different growth stages under different meteorological drought ***'an City in China was selected as the study area,and summer maize was selected as the research *** and crop yield data from 1951 to 2010 were used as the fundamental data to investigate drought degree mutation of summer *** results show that,under the meteorological drought conditions at the emergence-jointing stage,drought degree may change abruptly,and soil moisture content at the sowingemergence,jointing-tasseling,and tasseling-mature stages should be kept higher than 39%.

关键词： Cusp catastrophe Drought degree Crop growth period Soil moisture content Maize

Tuning the porosity of {Co12IICo8III（μ3-OH）24（X）}11+ supramolecular frameworks by reaction time for D2/H2 separation

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年

作者： Zhuozhou xie Zhu Zhuo Zi-Ang nan Qing Li xiufang Li Zi-xiu Lu Linzhe Lü Jin Liu Luyao Liu wenjing Wang Wei Wang Daqiang Yuan You-Gui Huang State Key Laboratory of Structure Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences University of Chinese Academy of Sciences xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi InstitutesChinese Academy of Sciences State Key Laboratory of Physical Chemistry of Solid Surfaces Department of Chemistry College of Chemistry and Chemical EngineeringXiamen University

Systematicly tuning the porosities of porous materials is crucial for targeted gas mixture separation,yet it remains a longstanding *** a common strategy,altering the phenylene ring count in the organic building units has been exploited to adjust pore apertures in metal organic frameworks （MOFs） and covalent organic frameworks （COFs）,resulting in only a stepwise pore size variation of approximately 2.8?.Unlike MOFs and COFs,the porosities for supramolecular assembly frameworks are highly dependent on the packings of the molecular building units in the *** above strategy cannot be applied to supramolecular assembly frameworks and other strategies are required to adjust pore apertures in supramolecular frameworks,especially to achieve porous materials with the optimal pore size for D2/H2separation （～3?）.Here,we successfully modulate the porosity of supramolecular frameworks of[CoII1+12CoIII8L12（μ3-OH）24（X）]1clusters （L=mono-deprotonated 1-iminoisoindole-3-amine,X=ClO?4or Cl?） by controlling the duration of self-assembly *** simply adjusting the reaction time,we obtain three[CoII12CoIII8L12（μ3-OH）24（X）]11+supramolecular frameworks:[CoII12CoIII8（μ3-OH）24（ClO4）L12)]·（Cl）4·（HCO2）7（1）,[CoII12CoIII8L12（μ3-OH）24（Cl）]·（ClOI4）4·（Cl）6·（HCO2）·（H2O）10（2）,and[CoI12CoIII8L12（μ3-OH）24（Cl）]·（Cl）11·（H2O）12（3）.The different stacking patterns of the[CoII12CoIII8L12（μ3-OH）24（X）]11+clusters in these frameworks lead to significantly varied stabilities and *** 1 exhibits permanent porosity with interconnected channels and maintains stability under harsh *** contrast,compound 2 is nearly nonporous,and compound 3 becomes unstable upon *** pores of compound 1 show higher affinity to D2than H2,and the pore aperture diameter of compound 1 （～3.06?） meets the optimal porosity for D2/***,compound 1 demonstrates moderate D2/H2separation at 77 K (retention time:～7 min/g for D2/H2/Ne （10/10/80 vol%） in a flow of 5 mL

关键词：

Multi-objective reservoir operation using particle swarm optimization with adaptive random inertia weights

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Water Science and Engineering 2020年第2期13卷 136-144页

作者： Hai-tao Chen wen-chuan Wang xiao-nan Chen Lin Qiu School of Water Resources North China University of Water Resources and Electric PowerZhengzhou 450046China Construction and Administration Bureau of South-to-North Water Diversion Middle Route Project Beijing 100038China

Based on conventional particle swarm optimization(PSO),this paper presents an efficient and reliable heuristic approach using PSO with an adaptive random inertia weight(ARIW)strategy,referred to as the ARIW-PSO algorithm,to build a multi-objective optimization model for reservoir *** the triangular probability density function,the inertia weight is randomly generated,and the probability density function is automatically adjusted to make the inertia weight generally greater in the initial stage of evolution,which is suitable for global *** the evolution process,the inertia weight gradually decreases,which is beneficial to local *** performance of the ARIWPSO algorithm was investigated with some classical test functions,and the results were compared with those of the genetic algorithm(GA),the conventional PSO,and other improved PSO ***,the ARIW-PSO algorithm was applied to multi-objective optimal dispatch of the Panjiakou Reservoir and multi-objective flood control operation of a reservoir group on the Luanhe River in China,including the Panjiakou Reservoir,Daheiting Reservoir,and Taolinkou *** validity of the multi-objective optimization model for multi-reservoir systems based on the ARIW-PSO algorithm was verified.

关键词： Particle swarm optimization Genetic algorithm Random inertia weight Multi-objective reservoir operation Reservoir group Panjiakou Reservoir