检索结果-南通市图书馆

Robust Sure Independence Screening for Ultrahigh Dimensional Non-normal Data

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第11期30卷 1885-1896页

作者： Wei zhong Wang Yanan Institute for Studies in Economics Department of StatisticsSchool of EconomicsXiamen University

Sure independence screening（SIS） has been proposed to reduce the ultrahigh dimensionality down to a moderate scale and proved to enjoy the sure screening property under Gaussian linear ***,the observed response is often skewed or heavy-tailed with extreme values in practice,which may dramatically deteriorate the performance of *** this end,we propose a new robust sure independence screening（RoSIS） via considering the correlation between each predictor and the distribution function of the *** proposed approach contributes to the literature in the following three folds： First,it is able to reduce ultrahigh dimensionality ***,it is robust to heavy tails or extreme values in the ***,it possesses both sure screening property and ranking consistency property under milder ***,we demonstrate its excellent finite sample performance through numerical simulations and a real data example.

关键词： Robustness sure independence screening sure screening property ultrahigh dimensionality variable selection

A low-to-high friction transition in gradient nano-grained Cu and Cu–Ag alloys

在线全文

学校读者我要写书评

暂无评论

Friction 2021年第6期9卷 1558-1567页

作者： Xiang CHEN zhong HAN Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China

A unique low-to-high friction transition is observed during unlubricated sliding in metals with a gradient nano-grained(GNG)surface *** persisting in the low-friction state(0.2–0.4)for tens of thousands of cycles,the coefficients of friction in the GNG copper(Cu)and copper-silver(Cu–5Ag)alloy start to increase,eventually reaching a high level(0.6–0.8).By monitoring the worn surface morphology evolution,wear-induced damage accumulation,and worn subsurface structure evolution during sliding,we found that the low-to-high friction transition is strongly correlated with distinct microstructural instabilities induced by vertical plastic deformation and wear-off of the stable nanograins in the subsurface layer.A very low wear loss of the GNG samples was achieved compared with the coarse-grained sample,especially during the low friction *** results suggest that it is possible to postpone the initiation of low-to-high friction transitions and enhance the wear resistance in GNG metals by increasing the GNG structural stability against grain coarsening under high loading.

关键词： gradient nano-grained metals Cu and Cu–Ag alloy low-to-high friction transition subsurface plastic deformation wear

A Theory of Semantic Information(Invited Paper)

在线全文

学校读者我要写书评

暂无评论

China Communications 2017年第1期14卷 1-17页

作者： Yixin zhong Beijing University of Posts and Telecommunications Haidian District Beijing 100876 China

The information really useful to humans must be the trinity of its three components: the form termed syntactic information, the meaning termed semantic information, and the utility termed pragmatic information. But the theory of information set up by Shannon in 1948 is a statistical theory of syntactic information. Thus, the trinity of information theories needs to be established as urgently as possible. Such a theory of semantic information will be presented in the paper and it will also be proved that it is the semantic information that is the unique representative of the trinity. This is why the title of the paper is set to "a theory of semantic information" without mentioning the pragmatic information.

关键词： semantic information information ecology knowledge intelligence information-knowledge-intelligence conversion

Structure–activity relationship and mechanisms of reagents used in scheelite flotation

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2015年第12期34卷 882-887页

作者： Wan-zhong Yin Ji-Zhen Wang zhong-Mei Sun School of Resource and Civil Engineering Northeastern University Design & Research Institute of Zijin

Effects of carboxylic acid collector, benzohydroxamic acid (BHA), sodium hexametaphosphate (SHAP), sodium silicate, and oxalic acid on scheelite flotation were studied through flotation tests, quantum chemical calculation, and flotation solution computational chemistry. In terms of the calculation results, the relationship between chemical reactions occurring on the scheelite surface and molecular structures of the reagents were analyzed. The results show that BHA and carboxylic acid collectors interact with scheelite in different forms and the recovery of scheelite using sodium oleate as collector declines successively from SHAP, sodium silicate, to oxalic acid. Moreover, it is found that the performance of depressant in scheelite flotation is directly related to the group electronegativity, indicating that the latter is a dominant factor that determines the former. These findings will be helpful to the academic research communities of scheelite flotation.

关键词： Scheelite Flotation Flotation reagents Structure–activity relationship

A Survey of Voltage-Controlled-Oscillator-Based ?∑ ADCs

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2022年第3期27卷 472-480页

作者： Yi zhong Nan Sun Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Department of Electrical and Computer Engineering The University of Texas at AustinAustinTX 78712USA

The benefits of technology scaling have fueled interest in realizing time-domain oversampling(?∑) of Analog-to-Digital Converters(ADCs). Voltage-Controlled Oscillators(VCO) are increasingly used to design ?∑ADCs because of their simplicity, high digitization, and low-voltage tolerance, making them a promising candidate to replace the classical Operational Transconductance Amplifier(OTA) in ?∑ ADC design. This work aims to provide a summary of the fully VCO-based ?∑ ADCs that are highly digital and scaling-friendly. This work presents a review of first-order and high-order VCO-based ?∑ ADCs with several techniques and architectures to mitigate the nonidealities introduced by VCO, achieving outstanding power efficiency. The contributions and drawbacks of these techniques and architectures are also discussed.

关键词： Voltage-Controlled Oscillator(VCO) Analog-to-Digital Converter(ADC) oversampling(?∑)ADC time-domain signal processing VCO-based?∑ADC

Portfolio Optimization under Entropic Risk Management

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2009年第7期25卷 1113-1130页

作者： Wei zhong Department of Finance and Control Science School of Mathematical Sciences Fudan University Shanghai 200433 China

framework in the risk uniqueness In this paper, properties of the entropic risk measure are examined rigorously in a general This risk measure is then applied in a dynamic portfolio optimization problem, appearing management constraint. By considering the dual problem, we prove the existence and of the solution and obtain an analytic expression for the solution.

关键词： entropic risk measure portfolio optimization risk management

Influence of the Coulomb exchange term on nuclear single-proton resonances

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第5期27卷 231-237页

作者： Shu-Yang Wang zhong-Lai Zhu zhong-Ming Niu School of Physics and Materials Science Anhui University

Nuclear single-proton resonances are sensitive to the Coulomb field,while the exchange term of Coulomb field is usually neglected due to its *** combining the complex scaling method with the relativistic mean-field model,the influence of the Coulomb exchange term on the single-proton resonances is investigated by taking Sn isotopes and N=82 isotones as *** is found that the Coulomb exchange term reduces the singleproton resonance energy within the range of 0.4-0.6 MeV and leads to similar isotopic and isotonic trends of the resonance energy as those without the Coulomb exchange ***,the single-proton resonance width is also reduced by the Coulomb exchange term,whose influence generally decreases with the increasing neutron number and increases with the increasing proton ***,the influence of the Coulomb exchange term cannot change the trend of the resonance width with respect to the neutron number and proton ***,the influence of the Coulomb exchange term on the resonance width is investigated for the doubly magic nuclei ^(40)Ca,^(56,78)Ni,^(100,132)Sn,and ^(208)*** is found that the Coulomb exchange term reduces the proton resonance width within 0.2 MeV,whose magnitude depends on the specific nucleus and the quantum numbers of resonant states.

关键词：共振能量库仑场交换项质子数相对论平均场模型共振宽度中子数非定域性

Predication of topological states in the allotropes of group-IV elements

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2021年第6期16卷 117-124页

作者： Chengyong zhong National Laboratory of Solid State Microstructures and Department of Physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China Institute for Advanced Study Chengdu UniversityChengdu 610106China

Three-dimensional(3D)topological insulators(TIs)have been studied for approximately fifteen years,but those made from group-IV elements,especially Ge and Sn,seem particularly attractive owing to their nontoxicity,sizable intrinsic spin–orbit coupling(SOC)strength and natural compatibility with the current semiconductor ***,group-IV elemental TIs have rarely been reported,except for the low temperature phase ofα-Sn under ***,based on first-principles calculations,we propose new allotropes of Ge and Sn,named T5-Ge/Sn,as desirable *** new allotropes are also highly anisotropic Dirac semimetals if the SOC is turned *** the best of our knowledge,T5-Ge/Sn are the first 3D allotropes of Ge/Sn that possess topological states in their equilibrium states at room ***,their isostructures of C and Si are metastable indirect and direct *** work not only reveals two promising TIs,but more profoundly,we justify the advantages of group-IV elements as topological quantum materials(TQMs)for fundamental research and potential practical applications,and thus reveal a new direction in the search for desirable TQMs.

关键词： topological insulators topological semimetals group-IV elements first-principles calculations

Circularly polarized phosphorescence and photon transport of micro/nanocrystals of ruthenium and iridium complexes with chiral anions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2023年第10期66卷 2892-2902页

作者： zhong-Qiu Li zhong-Liang Gong Tongling Liang Stefan Bernhard Yu-Wu zhong Jiannian Yao Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Laboratory of PhotochemistryCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Chemistry Carnegie Mellon UniversityPittsburghPennsylvania 15213USA

Materials with efficient circularly polarized phosphorescences(CPPs) are of potential use in advanced data encryption and anticounterfeiting, bioimaging, optoelectronic devices and so forth. Herein, a simple method is presented for the preparations of CPP-active micro/nanocrystals with large luminescence dissymmetry factors(glum), high phosphorescence quantum efficiencies(Φ_(P)) and tunable emission colors. Diastereomeric Ir^(Ⅲ) and Ru^(Ⅱ) complexes with chiral(±)-camphorsulfonate counter-anions are readily synthesized and assembled into crystalline microrods, microplates or nanofibers with ordered morphologies. The chirality information of chiral counter-anions is efficiently transferred to the metal components to afford CPPs with cyan, green,yellow, or red emission colors and Φ_(P)in the range of 5%–85%. The number of chiral anions is found to play a role in influencing the CPP magnitudes of these crystals. The dicationic Ru^(Ⅱ) and tricationic Ir^(Ⅲ) complexes show glumvalues in the 10^(-2)order, which are much larger with respect to those of monocationic Ir^(Ⅲ) complexes. Single crystal X-ray analysis is performed to obtain information on the chirality transfer of these materials. In addition, circularly polarized photonic signal waveguiding is demonstrated using the microcrystals of an Ir^(Ⅲ)complex. This work demonstrates an appealing strategy of constructing chiral micro/nano-architectures for potential applications in chiral nanophotonics.

关键词： circularly polarized luminescence transition metal complexes chirality transfer micro/nanocrystals photon transport

同方期刊数据库