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RAID 4SMR:RAID Array with Shingled Magnetic Recording disk for Mass Storage Systems

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Journal of Computer Science & Technology 2019年第4期34卷 854-868页

作者： Quoc Le Ahmed Amer JoAnne Holliday Department of Computer Engineering School of EngineeringSanta Clara UniversitySanta ClaraCA 95053U.S.A.

One way to increase storage density is using a shingled magnetic recording(SMR)*** propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared with a basic RAID 4 *** proposed scheme(called RAID 4SMR)has the potential to improve the performance of a traditional RAID 4 array with SMR *** evaluation shows that compared with the standard RAID 4,when using update in-place in RAID arrays,RAID 4SMR with garbage collection not just can allow the adoption of SMR disks with a reduced performance penalty,but offers a performance improvement of up to 56%.

关键词： disk array redundant array of independent disks(RAID) shingled magnetic recording(SMR) shingled write

Heat Transfer and Fluid Flow over a Single disk in a Fluid Rotating as a Rigid Body

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Journal of Thermal Science 2004年第3期13卷 279-282页

作者： Igor V. SHEVCHUK Matthias H. BUSCHMANN Institute of Engineering Thermophysics Ukrainian National Academy of Sciences 2a Zhelyabov St. Kiev 03057 UkraineInstitute of Fluid Mechanics Dresden University of Technology 01062 Dresden Germany

Laminar heat transfer problem is analyzed for a disk rotating with the angular speed ωin a co-rotating fluid (with the angular speed Ω). The fluid is swirled in accordance with a forced-vortex law, it rotates as a solid body at β= Ω/ω= const. Radial variation of the disk’s surface temperature follows a power law. An exact numerical solution of the problem is obtained basing on the self-similar profiles of the local temperature of fluid, its static pressure and velocity components. Numerical computations were done at the Prandtl numbers Pr = 1(?)0.71. It is shown that with increasing βboth radial and tangential components of shear stresses decrease, and to zero value at β= 1. Nusselt number is practically constant at β= 0(?) 0.3 (and even has a point of a maximum in this region); Nu decrease noticeably for larger βvalues.

关键词： rotating disk heat transfer fluid flow Nusselt number swirl.

Utilization of Maxwell-Cattaneo law for MHD swirling flow through oscillatory disk subject to porous medium

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Applied Mathematics and Mechanics(English Edition) 2019年第6期40卷 837-850页

作者： A. RAUF Z. ABBAS S. A. SHEHZAD Department of Mathematics The Islamia University of BahawalpurBahawalpur 63100Pakistan Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan

The present study aims to investigate the salient features of incompressible, hydromagnetic, three-dimensional flow of viscous fluid subject to the oscillatory motion of a disk. The rotating disk is contained in a porous medium. Furthermore, a time-invariant version of the Maxwell-Cattaneo law is implemented in the energy equation. The flow problem is normalized by obtaining similarity variables. The resulting nonlinear system is solved numerically using the successive over-relaxation method. The main results are discussed through graphical representations and tables. It is perceived that the thermal relaxation time parameter decreases the temperature curves and increases the heat trans- fer rate. The oscillatory curves for the velocity field demonstrate a decreasing tendency with the increasing porosity parameter values. Two- and three-dimensional flow phenom- ena are also shown through graphical results.

关键词： time-dependent flow oscillatory disk porous medium magnetohydrody-namic (MHD) Maxwell-Cattaneo law numerical solution

Optimization of passive control performance for different hard disk drives subjected to shock excitation

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Journal of Central South University 2017年第4期24卷 891-899页

作者： Seyed Rashid Alavi Mehdi Rahmati Saeed Ziaei-Rad Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156-83111 Iran Isfahan Mathematics House Isfahan 81698-51177 Iran

Laptop personal computers(LPCs) and their components are vulnerable devices in harsh mechanical environments. One of the most sensitive components of LPCs is hard disk drive(HDD) which needs to be protected against damages attributable to shock and vibration in order to have better magnetic read/write performance. In the present work, a LPC and its HDD are modeled as two degrees of freedom system and the nonlinear optimization method is employed to perform a passive control through minimizing peak of HDD absolute acceleration caused by a base shock excitation. The presented shock excitation is considered as half-sine pulse of acceleration. In addition, eleven inequality constraints are defined based on geometrical limitations and allowable intervals of lumped modal parameters. The target of the optimization is to reach optimum modal parameters of rubber mounts and rubber feet as design variables and subsequently propose new characteristics of rubber mounts and rubber feet to be manufactured for the HDD protection against shock excitation. The genetic algorithm and the modified constrained steepest descent algorithm are employed in order to solve the nonlinear optimization problem for three widely-used commercial cases of HDD. Finally, the results of both optimization methods are compared to make sure about their accuracy.

关键词： hard disk drive passive control shock excitation sequential quadratic programming genetic algorithm rubber

Heptanuclear brucite disk with cyanide bridges in a cocrystal and tracking its pyrolysis to an efficient oxygen evolution electrode

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Science Bulletin 2019年第22期64卷 1667-1674页

作者： Jian-Qiang Zhao Dandan Cai Jun Dai Mohamedally Kurmoo Xu Peng Ming-Hua Zeng Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources Department of Chemistry and Pharmaceutical SciencesGuangxi Normal UniversityGuilin 541004China Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional MoleculesCollege of Chemistry and Chemical EngineeringHubei UniversityWuhan 430062China Institut de Chimie de Strasbourg CNRS-UMR7177Universite de Strasbourg67070 Strasbourg CedexFrance

The development of efficient oxygen evolution reaction(OER)catalysts is still lacking in exploration of the mechanism of controlled pyrolysis of precursors among new material ***,a novel Co-based coordination molecular cluster has been first introduced as precursor to obtain metallic cobalt core shelled by N-doped carbon(Co@NC)structure which operates as an oxygen evolution ***,a new cocrystal compound,[Co7II(l3-CN)6(mmimp)6][CoIICl3N(CN)2]á3CH3OH(Co7+1,mmimp=2-methoxy-6-((methylimino)-methyl)phenol),was isolated consisting of Brucite disks of cobalt where the usual bridging l3-OH is replaced by l3-CN produced by the in-situ decomposition of dicyanamide(NC-N-CNà).The cobalt atoms are bonded through the nitrogen atom of the ***,time dependent thermogravimetric-mass spectrometry(TG-MS)analysis was utilized to track its pyrolysis *** allowed us to propose a possible formation process of the Co@NC structure from Co7+***,an extremely superior OER electrode is optimized for Co@NC-600 having the lowest overpotential of257 m V at 10 m A/cm2in 1 mol/L KOH *** present study pins down the importance of clusters of transition metals on realizing distinct nanostructures operating as highly efficient OER electrocatalyst.

关键词： Cobalt disk clusters Thermogravimetry-mass spectrometry Pyrolysis tracking Core-shell nanostructure Oxygen evolution reaction

CO2 absorption performance in a rotating disk reactor using DBU-glycerol as solvent

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Chinese Journal of Chemical Engineering 2020年第1期28卷 104-113页

作者： Hualing Duan Kun Zhu Houfang Lu Changjun Liu Kejing Wu Yingying Liu Bin Liang School of Chemical Engineering Sichuan UniversityChengdu 610065China Institute of New Energy and Low Carbon Technology Sichuan UniversityChengdu 610065China

Gas–liquid mass transfer of rotating disk reactor was studied in CO2 absorption using 1,8-diazabicyclo-[5.4.0]-undec-7-ene(DBU)-glycerol solution as solvent. Effects of the rotating disk structure and various operation parameters on the CO2 absorption rate and CO2 removal efficiency were investigated. The rotating disk with optimal holes is conducive to mass transfer of CO2 and the formation of thin liquid film at the opening increases the gas–liquid contact area. With the increase of rotating speed, the liquid flow pattern on the rotating disk surface changes from thin film flow to separated streams and creates extra liquid lines attached to the rim of the disk,which leads to a very complicated change on the CO2 absorption rate and CO2 removal efficiency. The overall gas-phase mass transfer coefficient increases 138% as the rotating speed increasing from 250 to 1400 r·min^-*** temperature from 298 to 338 K can enhance the CO2 absorption rate due to lowering the viscosity of the solvent. The rate-determined step for the absorption is focused on the gas side. The rotating disk reactor can effectively enhance the absorption of CO2 with viscous DBU-glycerol solvents.

关键词： Gas–liquid flow Carbon dioxide Rotating disk reactor Absorption rate Viscosity

Inner-product of strain rate vector through direction cosine in coordinates for disk forging

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Transactions of Nonferrous Metals Society of China 2006年第6期7卷 1320-1324页

作者：赵德文金文忠王磊刘相华 State Key Laboratory of Rolling and Automation Northeastern University

A new linear integration for plastic power was *** effective strain rate for disk forging with bulge was expressed in terms of two-dimensional strain rate vector,and then its direction cosines were determined by the ratio of coordinate ***,inner-product of the vector for plastic power was term integrated by term and ***,through a formula for determination of bulge an analytical solution of stress effective factor was ***,through compression tests,the calculated results of above formula were compared with those of Avitzur’s approximate solution and total indicator readings of the testing *** is indicated that the calculated compression forces are basically in agreement with the measured ones if the pass reduction is less than 13.35%.However,when the reduction gets up to 25.34% and 33.12%,the corresponding errors between the calculated and measured results also get up to 6% and 13.5%,respectively.

关键词： disk forging bulge strain rate vector direction cosine inner-product analytical solution

Unsteady three-dimensional MHD flow of the micropolar fluid over an oscillatory disk with Cattaneo-Christov double diffusion

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Applied Mathematics and Mechanics(English Edition) 2019年第10期40卷 1471-1486页

作者： A.RAUF S.A.SHEHZAD Z.ABBAS T.HAYAT Department of Mathematics COMSATS University Islamabad Sahiwal 57000 Pakistan Department of Mathematics The Islamia University of Bahawalpur Bahawalpur 63100 Pakistan Department of Mathematics Quiad-i-Azam University Islamabad 44000 Pakistan

Cattaneo-Christov heat and mass flux models are considered rather than Fourier and Fick laws due to the presence of thermal and concentration transport hyperbolic phenomena. The generalized form of the Navier-Stokes model is considered in hydromagnetic flow. Three-dimensional (3D) unsteady fluid motion is generated by the periodic oscillations of a rotating disk. Similarity transformations are used to obtain the normalized fluid flow model. The successive over relaxation (SOR) method with finite difference schemes are accomplished for the numerical solution of the obtained partial differential non-linear system. The flow features of the velocity, microrotation, temperature, and concentration fields are discussed in pictorial forms for various physical flow parameters. The couple stresses and heat and mass transfer rates for different physical quantities are explained via tabular forms. For better insight of the physical fluid model, 3D fluid phenomena and two-dimensional (2D) contours are also plotted. The results show that the micropolar fluids contain microstructure having non-symmetric stress tensor and are useful in lubrication theory. Moreover, the thermal and concentration waves in Cattaneo-Christov models have a significance role in the laser heating and enhancement in thermal conductivity.

关键词： three-dimensional (3D) flow micropolar fluid magnetohydrodynamics (MHD) Cattaneo-Christov theory oscillatory disk

Numerical Analysis of Magnetohydrodynamic Navier’s Slip Visco Nanofluid Flow Induced by Rotating disk with Heat Source/Sink

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Communications in Theoretical Physics 2019年第9期71卷 1075-1083页

作者： M.Awais S.Bilal M.Y.Malik Khalil-ur-Rehman Department of Mathematics AIR UniversitySector E-9Air ComplexIslamabad44000Pakistan Department of Mathematics College of SciencesKing Khalid UniversityAbha61413Saudi Arabia Department of Mathematics Quaid-i-Azam UniversityIslamabad44000Pakistan

Current exertion is made to depict and search out the flow features imparted to viscid fluid flow over a rotational disk. Impression of magnetic field with rotating fluid is generated by interacting it in radial *** structured particles with magnetized fluid are also incorporated in the upshot of chemical reaction and absorptive/generative heat induction. Von Kumaran procedure is executed to obtain flow narrating differential *** pattern regarding thermal, momentum profiles are comprehended with the support of shooting method and RungeKutta methods. Furthermore, to get more realistic view of result description computational algorithm is modified by improving Runge-Kutta coefficients with Cash and Carp method. The aspects of flow controlling parameters like momentum slip parameter, magnetic strength parameter, Brownian motion parameter, thermophoresis parameter are adorned in sketches. Findings of these architects are accumulated in conclusion section.

关键词： heat generation/absorption viscous fluid model nanoparticles rotating disk Navier slip Cash and Carp method