Structure and dynamics of Rh surfaces

Lattice relaxations, surface phonon spectra, surface energies, and work functions are calculated for Rh(100) and Rh(110) surfaces using density-functional theory and the full-potential linearized augmented plane wave method. Both, the local-density approximation and the generalized gradient approximation to the exchange-correlation functional are considered. The force constants are obtained from the directly calculated atomic forces, and the temperature dependence of the surface relaxation is evaluated by minimizing the free energy of the system. The anharmonicity of the atomic vibrations is taken into account within the quasiharmonic approximation. The importance of contributions from different phonons to the surface relaxation is analyzed.Comment: 9 pages, 7 figures, scheduled to appear in Phys. Rev. B, Feb. 15 (1998). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Electrolyte for aluminium electrolytic capacitor

A suitable electroyte has been formulated for aluminium electrolyte capacitor and its performance was studied over a temperature ranged- 2S0C to+ 85Oc The dirnatic, eledrical cheraderisitics and the life endurrance test d the capacitor using the devekped eledrdyte wem tested according to IS1 specification and the results are disarsse

A New Course on Supercomputers and Parallel Architectures

Parallel processing and distributed computing are two areas attracting a great deal of attention. Several universities and institutions are currently involved in the teaching of courses on parallel programming, distributed operating systems and parallel algorithms, but very few of them offer a course from the hardware point of view. The course structure presented in this paper gives a considerable emphasis on the hardware for parallel processing. Various topics such as the design of high speed computing devices, hardware design of multiple pipelines, design of a variety of memory configurations, design of an NXN interconnection network and the hardware for systolic architectures and neural network architectures are presented in this course. Students have the opportunity to actually design a distributed shared memory system using IBM PC machines and write software for them. The assignments for the course are in the form of both individual and group projects on the implementation of various schemes for parallel processing such as synchronization mechanisms (e.g., locks and barrier) in hardware. In addition, a group project deals with the design of a pipelined floating point unit. Further, a complementary course on VLSI provides the necessary skills for the students to implement the devices as a VLSI chip. Students also have the opportunity to do hands on work with transputers and develop hardware and software based around them. This course has been offered for the last three years and has received a good feedback both from academia and industries within Australia

Plating on anodised aluminium

Laboratory scale investigation on the use of sulphuric-oxalic acid anodismg bath for plating purposes are presented and the results of this bath are compared with other standard baths after plating in respect of coverage, adhesion etc. The experimental results indicate that direct plating of copper isquite possible on oxide films formed from sulphuric-oxalic acid bath with good coverage, adhesion and fairly higher thickness from an acid copper bath

Lead-tin-copper alloy deposition from fluoborate solutions

The eledrodeposition of lead-tinqper alloy from fluoborate solution has been reported. The effects of addition agent, armnt density, copper content and total metal content of the bath on the alloy amposition have been discussed. The structure of the alloy obtained has been compared with that of lead-tin alloy with the help of SEM

Chemical blackening of stainless steel

Chemical blackening of stainless steel from a chromic acid-aulphuric acid bath containing selenium compound as addition agent has been investigated. The effect of temperature, sulphuric acid concentration and additive concentretion on the Wenine charecteristics as well as the potential - time behaviour of the system have been studied. The corrosion resistance of the coating is also reporte

Hard anodising of internal bore of cylindrical aluminium alloy for engineering applications

Hard andisinad intemal bores d aluminium wide d i i used in shock absorbers cannot be canied out by the convenknal method d anodising. SO s b lty pe d jig has been fabricated to ha4d the rinps me over the other and the eledroMe is Rowed through the internal bore without seepage d the eledrolyte. The influence d the paramete& such as tempemiure, a r m t densily.Agw rate and the properties such as hardness, coating ratio and thickness were studied using different eleddyte systems

A software system for the generation of test data for Ada programs

This paper presents the design of a software system for generating test data for programs developed in Ada. The key feature of this system is that the problem of test data generation is treated entirely as a numerical optimisation problem and, as a consequence, this method does not suffer from the difficulties associated with input variable-dependent loops, array references, and modules calls that are found in symbolic execution systems. Instead, program instrumentation is used to solve a set of path constraints without explicitly knowing their form. The system supports not only the generation of integer and real data types, but also non-numerical discrete types such as characters and enumerated types

Pulse anodising using microprocessor controlled pulse unit

The influence of 'on' and 'off' times and the frequencies of pulses on the anodised film using conventional sulphuric acid bath with.the help of microprocessor unit have been studied. The properties of the oxide film with respect to hardness, coating weight and density are better, compared with conventional oxide film produced in sulphuric acid. The details on the control unit and results obtained are discussed