检索结果-南通市图书馆

MODELING AND ExPERIMENTAL RESEARCH Of fOUR-STRAND LOW-fREQUENCY ELECTROMAGNETIC CASTING ALUMINUM ALLOY

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2007年第3期20卷 157-166页

作者： J.C. Li B.f. Wang J.Z. cui School of Materials ＆ Metallurgy Inner Mongolia University of Science and Technology Baotou 014010 China The Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110004 China

With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density in the aluminum melt and magnetic field interaction of four coils applied with same currents were investigated. Calculating results showed that magnetic flux density in the aluminum melt was greatly improved and the magnetic field interaction among different coils was decreased when external part of mould is made of soft magnetic material. Based on the finding, a four-strand low-frequency electromagnetic casting 6063 aluminum alloy experiment was carried out in the laboratory . The experiment showed that the surface of the billet was smooth and had no exudations and cold shuts, the as-cast microstructures were fine, uniform, equiaxed, net-globular or globular under low-frequency electromagnetic field. The microstructure becomes finer with increased current value.

关键词： low-frequency electromagnetic casting finite element method aluminum alloy mould

Effects of Nanostructured Back Reflectors on the External Quantum Efficiency in Thin film Solar Cells

在线全文

学校读者我要写书评

暂无评论

Nano Research 2011年第2期4卷 153-158页

作者： Chingmei Hsu George f. Burkhard Michael D. McGehee Yi cui Department of Materials Science and Engineering Stanford University Stanford California 94305 USA Department of Applied Physics Stanlbrd University Stanlbrd California 94305 USA

Hydrogenated amorphous Si （a-Si：H） is a promising material for photovoltaic applications due to its low cost, high abundance, long lifetime, and non-toxicity. We demonstrate a device designed to investigate the effect of nanostructured back reflectors on quantum efficiency in photovoltaic devices. We adopt a superstrate configuration so that we may use conventional industrial light trapping strategies for thin film solar cells as a reference for comparison. We controlled the nanostructure parameters via a wafer-scale self-assembly technique and systematically studied the relation between nanostructure size and photocurrent generation. The gain/loss transition at short wavelengths showed red-shifts with decreasing nanostructure scale. In the infrared region the nanostructured back reflector shows large photocurrent enhancement with a modified feature scale. This device geometry is a useful archetype for investigating absorption enhancement by nanostructures.

关键词： Solar cells back reflector scattering solar energy amorphous silicon

A COMPREHENSIVE DEA APPROACH fOR THE RESOURCE ALLOCATION PROBLEM BASED ON SCALE ECONOMIES CLASSIfICATION

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

Journal of Systems Science & Complexity 2008年第4期21卷 540-557页

作者： xiaoya LI Jinchuan cui Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China.

This paper is concerned with the resource allocation problem based on data envelopment analysis （DEA） which is generally found in practice such as in public services and in production process. In management context, the resource allocation has to achieve the effective-efficient-equality aim and tries to balance the different desires of two management layers： central manager and each sector. In mathematical programming context, to solve the resource allocation asks for introducing many optimization techniques such as multiple-objective programming and goal programming. We construct an algorithm framework by using comprehensive DEA tools including CCR, BCC models, inverse DEA model, the most compromising common weights analysis model, and extra resource allocation algorithm. Returns to scale characteristic is put major place for analyzing DMUs＇ scale economies and used to select DMU candidates before resource allocation. By combining extra resource allocation algorithm with scale economies target, we propose a resource allocation solution, which can achieve the effective-efficient-equality target and also provide information for future resource allocation. Many numerical examples are discussed in this paper, which also verify our work.

关键词： Common weights analysis (CWA) date envelopment analysis (DEA) decision making unit (DMU) efficiency score inverse DEA model multiple-objective linear programming (MOLP) resource allocation problem returns to scale (RTS).

Message Authentication Codes Against Related-Key Attacks Under LPN and LWE

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2021年第4期30卷 697-703页

作者： cui Nan LIU Shengli Department of Computer Science and Engineering Shanghai Jiao Tong University State Key Laboratory of Cryptology

Message authentication code(MAC)guarantees the authenticity of messages and is one of the most important primitives in cryptography. We study related-key attacks with which the adversary is able to choose function f and observe the behavior of the MAC under the modified authenticated key f(k), and consider unforgeability of MAC under(selectively) chosen message attack with f(k). We focus on MAC schemes from the Learning parity with noise(LPN) and the Learning with errors(LWE) problem by Kiltz et al. in EUROCRYPT2011. We first prove that the MAC schemes from LPN/LWE can resist key-shift attacks and enlarge the key-shift function set to support a subclass of affine functions.

关键词： Related key attack Message authentication code Affine functions

Molecular Dynamics Simulations of the Effects of Surface Sinusoidal Nanostructures on Nanoscale Liquid film Phase-Change

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2020年第4期29卷 1076-1084页

作者： CAO Qun cui Zheng Institute of Thermal Science and Technology Shandong UniversityJinan 250061China

Nanostructures on heat transfer surfaces can enhance micro/nanoscale phase-change heat transfer processes. To understand the enhancement mechanisms provided by nanostructures, evaporation processes of nanoscale liquid films on periodic sinusoidal-shaped surfaces were investigated via molecular dynamics simulations. By changing the amplitudes(A) and periods(T) of the curves describing the sinusoidal shapes, which possess shapes similar to f(x)=h0+Asin(2πx/T), sinusoidal surfaces of different sizes were constructed. An unevaporated region always existed on the copper plate for all surfaces during phase-change processes. Moreover, we calculated the interfacial thermal resistances and the mismatches between the vibrational density of states of the solid and liquid for different surfaces. The results show that the argon temperature changes and evaporation rates during the phase-change process on sinusoidal surfaces are higher than those on flat surfaces, and these results increase with the increase in amplitudes and the decrease in periods within certain limits mainly because of the thermal resistance decrease at the solid-liquid interface. furthermore, the corresponding mismatches between the vibrational density of states of the solid and liquid also decrease, which indicates that the existence of sinusoidal nanostructures enhances the heat transfer of the phase-change process.

关键词： molecular dynamics simulation sinusoidal surface phase-change interfacial thermal resistance nanoscale

Recent Progress in Exploiting Small Molecule Peptides as Supramolecular Hydrogelators

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2017年第10期35卷 1194-1211页

作者： Hao Su Yuzhu Wang Caleb f.Anderson Jin Mo Koo Han Wang Honggang cui Department of Chemical and Biomolecular Engineering The Johns Hopkins University Baltimore Maryland 21218 USA Institute for NanoBio Technology The Johns Hopkins University Baltimore Maryland 21218 USA Department of Oncology and Sidney Kimmel Comprehensive Cancer Center Johns Hopkins University School of Medicine Baltimore MD 21205 USA Center for Nanomedicine The Wilmer Eye Institute Johns Hopkins University School of Medicine 400 North Broadway Baltimore MD 21231 USA

Small molecule peptides and their derivatives are an emerging class of supramolecular hydrogelators that have attracted rapidly growing interest in the fields of drug delivery and regenerative medicine due to their inherent biodegradability and biocompatibility, as well as versatility in molecular design and ease of synthesis. Built upon the directional, intermolecular interactions such as hydrogen bonding and π-π stacking, peptide-based molecular units can associate in aqueous solution into filamentous assemblies of various sizes and shapes. Under appropriate conditions, these filamentous assemblies can percolate into a 3D network with materials properties tailorable for specific biomedical applications. In this review, we survey the literature published over the past three years in the development of peptide-based hydrogelators for biomedical applications. We highlight several representative examples and center our discussion on the fundamentals of molecular design, assembly, and gelation conditions.

关键词： PNIPAM spheres reversible assembled colloidal Highly ordered assembly leaving anhydride

Generalized f-Test for High Dimensional Regression Coefficients of Partially Linear Models

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2017年第5期30卷 1206-1226页

作者： WANG Siyang cui Hengjian School of Statistics and Mathematics Central University of Finance and EconomicsBeijing 100081China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

This paper proposes a test procedure for testing the regression coefficients in high dimensional partially linear models based on the f-statistic. In the partially linear model, the authors first estimate the unknown nonlinear component by some nonparametric methods and then generalize the f-statistic to test the regression coefficients under some regular conditions. During this procedure, the estimation of the nonlinear component brings much challenge to explore the properties of generalized f-test. The authors obtain some asymptotic properties of the generalized f-test in more general cases,including the asymptotic normality and the power of this test with p/n ∈(0, 1) without normality assumption. The asymptotic result is general and by adding some constraint conditions we can obtain the similar conclusions in high dimensional linear models. Through simulation studies, the authors demonstrate good finite-sample performance of the proposed test in comparison with the theoretical results. The practical utility of our method is illustrated by a real data example.

关键词： Generalized f-test high dimensional regression partially linear models power of test.

formation of Nitride Cu3N by MeV N-Ion Implantation into Cu

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1991年第10期8卷 525-528页

作者： cui fuzhai A.M.Vredenberg R.de Reus f.W.Saris Department of Materials Science and Engineering Tsinghua.Universityf Beijing 100084 fOM-Institu£e for Atomic and Molecular Physics Kruislaan 4071098 SJ AmsterdamThe Netherlands

Experimental evidences are presented to show the formation of jiiCride,Cu3N,in pure Cu sample by N-ion *** result is obtained in the case of MeV ion *** experiments showed that this compound can not be formed by N-ion implantation into Cu at incident energy of about 100keV,This Ending indicates there exist certain differences in phase forma-tion by ion implcLntation at the two energies.

关键词： implantation pure incident

New ultrasound techniques for lymph node evaluation

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

World Journal of Gastroenterology 2013年第30期19卷 4850-4860页

作者： xin-Wu cui Christian Jenssen Adrian Saftoiu Andre Ignee Christoph f Dietrich Med.Klinik 2 Caritas-Krankenhaus97980 Bad MergentheimGermany Klinik für Innere Medizin Krankenhaus M rkisch Oderland15334 StrausbergGermany Department of Gastroenterology Research Center of Gastroenterology and HepatologyUniversity of Medicine and Pharmacy Craiova200349 CraiovaRomania

Conventional ultrasound(US)is the recommended imaging method for lymph node(LN)diseases with the advantages of high resolution,real time evaluation and relative low *** indications of transcutaneous ultrasound and endoscopic ultrasound include the detection and characterization of lymph nodes and the guidance for LN *** advances in US technology,such as contrast enhanced ultrasound(CEUS),contrast enhanced endoscopic ultrasound(CE-EUS),and real time elastography show potential to improve the accuracy of US for the differential diagnosis of benign and malignant lymph *** addition,CEUS and CE-EUS have been also used for the guidance of fine needle aspiration and assessment of treatment *** to size criteria,CEUS could also be used to evaluate response of tumor angiogenesis to anti-angiogenic *** this paper we review current literature regarding evaluation of lymphadenopathy by new and innovative US techniques.

关键词： Lymph nodes Ultrasound Endoscopic ultrasound Lymph node metastasis Lymphoma