Simulation studies on a rotating ring disk electrode: Effects of ionic migration with kinetic complication-disk results

In continuation to my previous work (Guha S. AIChE J. 2013;59(4):1390-1399), in this work, effects of ionic migration are evaluated for disk region of a rotating ring disk electrode system by numerically solving complex differential equations, developed for mass transfer along with kinetic complication in presence of ionic migration under limiting current condition. The system for simulation is 0.01 M Fe₂(SO₄)₃ solution with H₂SO₄ as supporting electrolyte. Simulation cases are presence and absence of ionic migration with kinetic complication (oxidation of Fe²⁺ to Fe³⁺ under O₂ pressure). Results show that concentration boundary layer thickness of reactant Fe³⁺ reduces appreciably and steady-state disk current reduces substantially in presence of migration. Simulated steady-state disk current in absence of migration case agrees well with published data. Results indicate higher Fe²⁺ concentration in presence of migration and thereby higher rate of oxidation of Fe²⁺ to Fe³⁺ at all rate constant values.     

Electrochemical mass transfer between an impinging jet and a rotating disk in a confined system

This paper presents the mass transfer results from an impinging liquid jet to a rotating disk. The mass transfer coefficients were measured using the electrochemical limiting diffusion current technique (ELDCT). Rotational Reynolds number (Re_r) in the range of 3.4 × 10⁴–1.2 × 10⁵, jet Reynolds number (Re_j) 1.7 × 10⁴–5.3 × 10⁴ and non-dimensional jet-to-disk spacing (H/d) 2–8 were taken into consideration as parameters. It was found that the jet impingement resulted in a substantial enhancement in the mass transfer compared to the case of the rotating disk without jet.     

Midplane-symmetry breaking in the flow between two counter-rotating disks

This paper considers the axisymmetric steady flow driven by exact counter rotation of two co-axial disks of finite radius. At the edges of the rotating disks one of three conditions is (typically) imposed: (i) zero velocity, corresponding to a stationary, impermeable, cylindrical shroud (ii) zero normal velocity and zero tangential fluid traction, corresponding to a (confined) free surface and (iii) an edge constraint that is consistent with a similarity solution of von Kármán form. The similarity solution is valid in an infinite geometry and possesses a pitchfork bifurcation that breaks the midplane symmetry at a critical Reynolds number. In this paper, similar bifurcations of the global (finite-domain) flow are sought and comparisons are made between the resulting bifurcation structure and that found for the similarity solution. The aim is to assess the validity of the nonlinear similarity solutions in finite domains and to explore the sensitivity of the solution structure to edge conditions that are implicitly neglected when assuming a self-similar flow. It is found that, whilst the symmetric similarity solution can be quantitatively useful for a range of boundary conditions, the bifurcated structure of the finite-domain flow is rather different for each boundary condition and bears little resemblance to the self-similar flow.     

改善磁盘阵列性能的方法

磁盘阵列是解决计算机Ｉ／Ｏ瓶颈问题的有效方法之一，通过对现有磁盘阵列结构的研究，提出了４种改善磁盘阵列性能的方法，即良分利用磁盘带宽，平衡多盘的负载，减少奇偶检验数据存取时间和磁盘阵列Ｃａｃｈｅ技术等，分析结果表明：在事务处理应用领域，利用Ｃａｃｈｅ来把小写转化为大写可大大改善目前一般情况下，以一道数据大小来作为磁盘的基本存取大小是合适的选择，磁盘阵列负载平衡设计不足是指正常模式下系统请求在多盘间     

凸轮机构基圆半径的确定方法及其分析

基圆半径的确定方法，除了用图解法和试算法外，还可用解析法和图解分析法求解。４种方法各有优缺点，设计时要根据具体情况选择。     

某型杀伤枪榴弹引信弹道炸原因分析及再设计思考

通过对某型杀伤枪榴弹引信所发生的三次弹道炸的原因进行分析，提出用延期索替代延期药盘，并对有关机构进行再设计的对策。     

蝶阀加工及装配工艺的研究

传统工艺加工阀体、活门时，对机床的性能要求较高，一般为数控镗床。介绍了一种采用普通镗床加工阀体、活门的工艺方法及蝶阀在厂内装配的工艺方法。     

A study on UV-curable coatings for HD-DVD: Primer and top coats

This study relates to the development of coatings for optical discs in high-density digital versatile disc systems (HD-DVD or blue lay disk) that use a high numerical aperture of 0.85 at 405 nm wavelength and have a protective top layer over a primer layer for protection against damage and dust. Ultraviolet-curable raw materials of two acrylic monofunctional monomers ( isobornylacrylate, IBA and tetrahydrofurfurylacrylate, THFA) and two kinds of urethaneacrylate oligomers (OUMD and OUME) have been easily mixed with photoinitiators. Curing rate of these materials was characterized by FT-IR. In case of top coats, VTES (vinyltriethoxysilane) and acrylic acid were added to enhance the abrasion resistance. These two kinds of UV-curable resinous materials having no solvent were synthesized and investigated as means for making a blue ray disk having good optical and mechanical properties. In addition, dynamic characteristics including reflectivity, fluctuation of RF signal and noise level were also investigated.     

对电视安全播出的几点思考

从电视节目安全播出的角度出发，探讨如何采取切实有效的措施，确保电视节目的安全优质播出，力争使电视台的安全播出上一个新台阶，主要从播控系统的安全可靠性以及管理措施等方面进行阐述。     

THE FLOW PRODUCED IN PARTICLE-SUSPENSION BY AN INFINITE ROTATING DISK:SERIES SOLUTION

To the flow produced in particle-suspension by a rotating disk of infinite extent,the asymptotic behavior at infinity is analyzed.A corresponding series solution is presented.It isshown that this approach yields widely valid solutions of high accuracy for all the cases in whichthat suction or weak injection at the disk surface exists.For the cases that strong injection or par-ticle-free band exists,the series method fails.