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IEEE Globecom Workshops

作者： Prasanna Madhusudhanan Juan G. Restrepo Youjian Liu Timothy X Brown Department of Electrical Computer and Energy Engineering University of Colorado Boulder CO USA Department of Applied Mathematics University of Colorado Boulder CO USA Department of Electrical Computer and Energy Engineering Interdisciplinary Telecommunications Program University of Colorado Boulder CO USA

We study the downlink signal-to-interference ratio (SIR) in a multi-tier heterogeneous cellular network under the open and closed access schemes. Each tier is characterized by a base-station (BS) arrangement according to a homogeneous Poisson point process with certain density, constant transmission power and random shadow fading factors with arbitrary distribution. The mobile-station (MS) communicates with the BS that has the maximum instantaneous received power among those to which it is allowed access. The chosen BS provides coverage to the MS if the SIR is above a certain threshold determined by the BS's tier. The coverage probability and average rate expressions are derived for the open access scheme for any arbitrary SIR threshold assigned for each tier, and for the closed access scheme when the SIR thresholds are greater than one.

关键词： Fading Macrocell networks Random variables Measurement Computational modeling Femtocell networks Downlink

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Density-decomposed orbital-free density functional theory for covalently bonded molecules and materials

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Physical Review B 2012年第23期86卷 235109-235109页

作者： Junchao Xia Emily A. Carter Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544-5263 USA Program in Applied and Computational Mathematics and Andlinger Center for Energy and the Environment Princeton University Princeton New Jersey 08544-5263 USA

We propose a density decomposition scheme using a Wang-Govind-Carter- (WGC-) based kinetic energy density functional (KEDF) to accurately and efficiently simulate various covalently bonded molecules and materials within orbital-free (OF) density functional theory (DFT). By using a local, density-dependent scale function, the total density is decomposed into a highly localized density within covalent bond regions and a flattened delocalized density, with the former described by semilocal KEDFs and the latter treated by the WGC KEDF. The new model predicts reasonable equilibrium volumes, bulk moduli, and phase-ordering energies for various semiconductors compared to Kohn-Sham (KS) DFT benchmarks. The decomposition formalism greatly improves numerical stability and accuracy, while retaining computational speed compared to simply applying the original WGC KEDF to covalent materials. The surface energy of Si(100) and various diatomic molecule properties can be stably calculated and also agree well with KSDFT benchmarks. This linear-scaled, computationally efficient, density-partitioned, multi-KEDF scheme opens the door to large-scale simulations of molecules, semiconductors, and insulators with OFDFT.

关键词： PHYSICAL sciences research MOLECULES SEMICONDUCTORS BENCHMARKING (Management) CRYSTALS SURFACE energy COVALENT bonds (Chemistry)

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Parameters and scalings for dry and immersed granular flowing layers in rotating tumblers

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Physical Review E 2012年第1期86卷 011304-011304页

作者： Florent Pignatel Caroline Asselin Lucas Krieger Ivan C. Christov Julio M. Ottino Richard M. Lueptow Department of Mechanical Engineering Northwestern University Evanston Illinois 60208 USA French Air Force Academy Salon de Provence France Department of Chemical and Biological Engineering Northwestern University Evanston Illinois 60208 USA Department of Engineering Sciences and Applied Mathematics Northwestern University Evanston Illinois 60208 USA The Northwestern Institute on Complex Systems (NICO) Northwestern University Evanston Illinois 60208 USA

The scaling properties of the continuous flowing layer in a quasi-2D circular tumbler half filled with a granular material are studied experimentally in the presence of three different interstitial fluids (air, water, and glycerine). In the dry case, the dimensionless flowing layer thickness δ0/d scales with the dimensionless flow rate Qdry*=Q/(dgd), where Q is the flow rate, d is the particle diameter, and g is the acceleration due to gravity, in agreement with previous studies. However, unlike previous studies, we show that the exponent for the power-law relation between the two depends on the range of Qdry*. Meanwhile, the angle of repose increases linearly with Qdry*. In the immersed case, the interstitial fluid changes the relevant time scales, which can be accommodated by considering the fluid properties. The result is that there are two different expressions for the dimensionless flow rate in the immersed flow; one corresponding to a free fall regime for a large Stokes number, and one corresponding to a viscous regime at small Stokes number. On this basis, a single dimensionless flow rate that incorporates both buoyancy and viscous friction is proposed. The effect of side walls is also investigated. For dry flows and those immersed in water, the thickness of the flowing layer decreases while the slope of the free surface increases as the gap separating the walls becomes smaller. For immersed granular flows with glycerine as the interstitial fluid, however, the ratio of the thickness of the flowing layer to the bead diameter is independent of the distance the between the side walls because viscous effects dominate.

关键词： BUOYANCY-driven flow VISCOUS flow GRANULAR materials HYDRODYNAMICS EXPERIMENTS

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A Directional Entropic Force Approach to Assemble Anisotropic Nanoparticles into Superlattices†

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Angewandte Chemie 2013年第52期125卷

作者： Kaylie L. Young Michelle L. Personick Michael Engel Pablo F. Damasceno Stacey N. Barnaby Reiner Bleher Tao Li Sharon C. Glotzer Byeongdu Lee Chad A. Mirkin Department of Chemistry and International Institute for Nanotechnology Northwestern University 2145 Sheridan Road Evanston IL 60208 (USA) Department of Chemical Engineering Department of Materials Science & Engineering Applied Physics Program University of Michigan North Campus Research Complex 2800 Plymouth Road Ann Arbor MI 48109 (USA) Department of Materials Science and Engineering Northwestern University 2200 Campus Drive Evanston IL 60208 (USA) X‐ray Science Division Argonne National Laboratory 9700 South Cass Avenue Argonne IL 60439 (USA)

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Optimal Filling of Shapes

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Physical Review Letters 2012年第19期108卷 198304-198304页

作者： Carolyn L. Phillips Joshua A. Anderson Greg Huber Sharon C. Glotzer Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA Department of Chemical Engineering University of Michigan Ann Arbor Michigan 48109 USA Center for Cell Analysis and Modeling University of Connecticut Health Center Farmington Connecticut 06032 USA Department of Cell Biology University of Connecticut Health Center Farmington Connecticut 06032 USA Department of Mathematics University of Connecticut Storrs Connecticut 06032 USA Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA

We present filling as a type of spatial subdivision problem similar to covering and packing. Filling addresses the optimal placement of overlapping objects lying entirely inside an arbitrary shape so as to cover the most interior volume. In n-dimensional space, if the objects are polydisperse n-balls, we show that solutions correspond to sets of maximal n-balls. For polygons, we provide a heuristic for finding solutions of maximal disks. We consider the properties of ideal distributions of N disks as N→∞. We note an analogy with energy landscapes.

关键词： SHAPES FORCE & energy COMBINATORIAL packing & covering ANALOGY HEURISTIC THEORY of distributions (Functional analysis)

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Magnetic Studies in Rare Earth-iron Oxalate-bridged Complexes MFe（C2O4）3·9H2O （M=Ce、Pr）

Magnetic Studies in Rare Earth-iron Oxalate-bridged Complexe...

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2012 International Conference on Solid State Devices and Materials Science(SSDMS 2012)

作者： Qing Lin Chenglong Lei Hui Zhang Xuehui Long Jianmei Xu Fupei Liang Ruijun Wang Siliang Zeng Yun He College of Physics and Technology Guangxi Normal University Department of Information Technology Hainan Medical College College of Chemistry and Chemical Engineering Guangxi Normal University Institute of Applied Physics and Computational Mathematics

The rare earth-iron oxalate-bridged complexes Ce Fe(C2O4)3·9H2O and Pr Fe(C2O4)3·9H2O have been synthesized. In the sample Ce Fe(C2O4)3·9H2O, the magnetic susceptibilities of the compound can be fit to the Curie-Weiss law and Weiss paramagnetic Curie temperature of θ=-*** hyperfine field parameters show that the dependent of the hyperfine field and the spontaneous magnetization and that of the spontaneous magnetization and temperature in the latticed Fe II and Fe *** are a clear bifurcation phenomenon of the field-cooled(MFC) and Zero-field-cooled(MZFC) magnetization curves at the Ne′el temperature(4 K).In the sample Pr Fe(C2O4)3·9H2O,the Weiss paramagnetic Curie temperature θ=-2.7 K,There are a bifurcation of the ZFC and FC plots at the Ne′el temperature(6 K).The negative Weiss constant indicates an intramolecular antiferromagnetic coupling interaction between the adjacent Fe(II) and Fe(III) ions through the oxalate *** oxalate group has been shown to be an excellent bridging ligand in supporting the magnetic exchange interaction.

关键词： Oxalate rare earth materials susceptibility magnetic interaction

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Multiple Magnetic Pole Reversals and M?ssbauer Studies in Molecular-based Mixed Valency Ferrimagnet {[N（nC4H9）4][MⅡFeⅢ（C2O4）3]}n （M=Zn、Fe）

Multiple Magnetic Pole Reversals and M?ssbauer Studies in Mo...

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2012 International Conference on Solid State Devices and Materials Science(SSDMS 2012)

作者： Qing Lin Chenglong Lei Guodong Tang Qingmei Zhang Xinlong Dong Fupei Liang Ruijun Wang Siliang Zeng Yun He College of Physics and Technology Guangxi Normal University Department of Information Technology Hainan Medical College College of Chemistry and Chemical Engineering Guangxi Normal University Institute of Applied Physics and Computational Mathematics

The Molecule magnets Materials {[N(n-C4H9)4][MⅡFe Ⅲ(C2O4)3]}n M=Zn Fe were investigated by magnetic measurements and M?ssbauer *** the complex {[N(n-C4H9)4][Zn Ⅱ0.03 Fe Ⅱ0.97 Fe Ⅲ(C2O4)3]}n detailed investigation of the ferromagnetism behaviour, and a compensation temperature has found with the field being less than 1KOe. And the 57 Fe M?ssbauer measurements had been carried out in {[N(nC4H9)4][Fe ⅡFe Ⅲ(C2O4)3]}n to investigate the mixed valency character and antiferromagnetic coupling. Some ferrimagnets consisting of magnetic anisotropy ions and two or more types of antiferromagnetically ordered magnetic ions exhibit this behavior. As the temperature was lowered to 40 K, the Fe Ⅲ doublet subspectrum almost completely turns into a sextet subspectrum. The hyperfine magnetic field increases as the temperature decreasing.

关键词： Molecule-based magnet M?ssbauer spectroscopy spin glass

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Shear Strength of Single Lap Joint Aluminium-Thermoplastic Natural Rubber (Al-TPNR) Laminated Composite

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Journal of Physics: Conference Series 2013年第1期423卷

作者： M Z Muzakkar S Ahmad M A Yarmo A Jalar M Bijarimi School of Applied Physics Faculty of Science and Technology Universiti Kebangsaan Malaysia 43000 Bangi Selangor Malaysia Department of Chemistry Faculty of Mathematics and Science Universitas Haluoleo Kendari 93232 Indonesia Faculty of Chemical and Natural Resources Engineering Universiti Malaysia Pahang 26300 Kuantan Malaysia To whom any correspondence should be addressed School of Chemical Sciences and Food Technology Faculty of Science and Technology Universiti Kebangsaan Malaysia 43000 Bangi Selangor Malaysia

In this work, we studied the effect of surface treatment on the aluminium surface and a coupling agent to improve adhesion between aluminium with organic polymer. Thermoplastic natural rubber (TPNR) matrix was prepared by melt blending of natural rubber (NR), liquid natural rubber (LNR) compatibilizer, linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH). The PEgMAH concentration used was varied from 0% – 25%. In addition, the aluminium surface was pre-treated with 3-glycidoxy propyl trimethoxy silane (3-GPS) to enhance the mechanical properties of laminated composite. It was found that the shear strength of single lap joint Al-TPNR laminated composite showing an increasing trend as a function of PE-g-MAH contents for the 3-GPS surface treated aluminium. Moreover, the scanning electron microscope (SEM) revealed that the strength improvement was associated with the chemical state of the compound involved.

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Estimated radiation dose reduction using non-linear diffusion method in computed radiography

Estimated radiation dose reduction using non-linear diffusio...

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34th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBS 2012

作者： Sanchez, Ma. Guadalupe Juste, Belen Vidal, Vicente Verdu, Gumersindo Mayo, Patricia Rodenas, Francisco Universitat Politècnica de València Valencia Spain Polytechnic University of Valencia Spain Department of Informatics Systems and Computing Universitat Politècnica de València Valencia Spain Department of Chemical and Nuclear Engineering Universitat Politècnica de València Valencia Spain TITANIA Technology Services Grupo Dominguis Valencia Spain Departament of Applied Mathematics Universitat Politècnica de València Valencia Spain

ISBN: (纸本)9781424441198

In this paper we use a non-linear diffusion method to filter the inherent noise in a Computed Radiography (CR) for reducing the dose absorbed by the patients especially children in pediatric applications, related with the exposure mAs. The method is implemented in order to create a lower CR dose based on the selection of lower X-ray exposure and with a reduction of the noise using a non-linear diffusion method. The impact of several milliAmpere-seconds (mAs) setting on image quality has been studied using the RANDO phantom. The obtained results show good agreements between the filtered images and real images in terms of noise variance measurements. The new CR images allow medical researchers to analyze how a low dose affects the patient diagnosis. © 2012 IEEE.

关键词： Diffusion

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Metabolite biomarker discovery for metabolic diseases by flux analysis

Metabolite biomarker discovery for metabolic diseases by flu...

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IEEE International Conference on Systems Biology

作者： Limin Li Hao Jiang Wai-Ki Ching Vassilis S. Vassiliadis Institute of Information and System Science Xi'an Jiaotong University Xi'an China Advanced Modeling and Applied Computing Laboratory Department of Mathematics University of Hong Kong Hong Kong China Department of Chemical Engineering and Biotechnology University of Cambridge Cambridge UK

Metabolites can serve as biomarkers and their identification has significant importance in the study of biochemical reaction and signalling networks. Incorporating metabolic and gene expression data to reveal biochemical networks is a considerable challenge, which attracts a lot of attention in recent research. In this paper, we propose a promising approach to identify metabolic biomarkers through integrating available biomedical data and disease-specific gene expression data. A Linear programming (LP) based method is then utilized to determine flux variability intervals, therefore enabling the analysis of significant metabolic reactions. A statistical approach is also presented to uncover these metabolites. The identified metabolites are then verified by comparing with the results in the existing literature. The proposed approach here can also be applied to the discovery of potential novel biomarkers.

关键词： Biochemistry Diabetes Humans Obesity Gene expression Bioinformatics

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