Problems and experiences in nuclear data processing in developing countries

This article offers a summary of many interesting experiences and problems the authors have come across while making attempts to develop RAMBHA, the Kalpakkam processing code system for multigrouping neutron interaction cross section data for fast reactor applications. Many of the problems are due to limitations arising from the nature of computer facility including memory restraints. Also offered here is an interesting comparison of non-adjusted ENDF/B-IV based RRC multigroup cross-section set with 1969 adjusted French set. An attempt is made to highlight the impact of processing uncertainties on reactor parameters by two examples.     

Influence of inhibitors on corrosion and anodic behaviour of different grades of aluminium in alkaline media

The electrochemical properties of different grades of aluminium are said to be dependent on the presence of minor amounts of iron and silicon impurities. This investigation aims mainly at addressing the influence of different inhibitors (e.g., sodium stannate, sodium citrate and calcium oxide combinations) on properties such as corrosion, anodic behaviour and anode utilization efficiency of different grades of aluminium in alkaline media.     

Significance of carotid restenosis following endarterectomy

The purpose of this study was to determine whether Vietnam veterans' risk for posttraumatic stress disorder (PTSD) was correlated with their premilitary school performance. The authors compared both primary and secondary school record data on hospitalized chemically dependent PTSD patients with those of both non-PTSD, chemically dependent and community controls. All participants were male Vietnam war combat veterans. The comparisons were made with MANCOVA analyses with the effects of combat and age differences between groups controlled. For the most part, primary-school grade point average, absenteeism, and tardiness data on three groups did not differ significantly. However, the mean secondary school grade points of the future PTSD patients were generally substantially lower than those of controls. Additionally, more secondary school absenteeism and tardiness were reported among future PTSD patients than in the controls. The groups did not differ significantly on number of extracurricular activities. Academic weakness, absenteeism, and tardiness in secondary school appear to be moderately strong predictors of vulnerability to PTSD after traumatization. It also supports the claim that chronic PTSD is, in part, the result of weaknesses present before exposure to trauma.     

The hyper-deBruijn networks: scalable versatile architecture

Both Hypercube and deBruijn networks possess desirable properties. It should be understood, though, that some of the attractive features of one are not found in the other. The architecture proposed in this paper is a combination of these architectures, providing some of the desirable properties of both the networks such as admitting many computationally important networks, flexibility in terms of connections per node as well as level of fault-tolerance. Also the network allows a simple VLSI layout, scalability as well as decomposability. Thus, these networks can be a potential candidate for VLSI multiprocessor networks. The proposed network possesses logarithmic diameter, optimal connectivity, and simple routing algorithms amendable to networks with faults. Importantly, in addition to being pancyclic, these hyper-deBruijn networks admit most computationally important subnetworks including rings, multidimensional meshes, complete binary trees, and mesh of trees with perfect dilation. Techniques for optimal one-to-all (OTA) broadcasting in these networks are presented. As an intermediate result, this technique provides the fastest OTA broadcasting in binary deBruijn networks as well. The recent renewed interest in binary deBruijn networks makes this later result valuable     

Studies on dynamic behaviour of a cantilever square plate with varying thickness

The effects of different types of variations in profile and thickness on the amplitude and the dynamic bending stresses of a square cantilever plate excited by a point harmonic load resonance has been investigated. A four-noded plate bending element has been used for the analysis. The response has been determined for the first three modes of vibration. In each case the results obtained for different thickness variations are compared with those of the uniform thickness plate. It is observed that considerable reductions in amplitude and/or bending stresses can be achieved by the proper selection of thickness variation.     

A microprocessor-based dual slope phase meter

A dual-slope phase meter has been designed and tested to investigate its limitations. The design does not require a time standard; it offers good resolution, relative simplicity, low sensitivity to changes of internal circuit parameters, and microprocessor compatibility. The idea is based on a single-slope approach demonstrated by W.T. Davis (1986), but several disadvantages of the system have been eliminated. The main problem with the system, relating to the error due to the finite time of sampling, is discussed     

Characterization of recrystallization and grain growth in Ti-7.4 At. Pct Al (cph) and Ti-15.2 At. Pct Mo (bcc) alloys

Quantitative microscopy, texture and grain growth kinetic studies were made on swaged and recrystallized Ti-7.4 at. pct Al and Ti-15.2 at. pct Mo alloys. The quantitative microscopy studies indicated that the grain size distribution in both alloys is a constant for a given grain size, independent of annealing time and temperature and follows a log normal distribution. Moreover, there exists a range of grain sizes in space; the relative quantities of each size in the range varies with average grain size. Also, the grain shape factor decreases with increase in annealing time (grain size) at a constant temperature and with decrease in temperature for a constant grain size. The values of the shape factor for a given grain size and temperature were approximately the same for the two alloys. The quantitative microscopy features were essentially the same as those observed by Okazaki and Conrad for unalloyed titanium. The texture of the as-swaged Ti-7.4 at. pct Al wire specimens and the changes in this texture during grain growth were in accord with those previously reported for deformed and recrystallized titanium. The Ti-15.2 at. pct Mo alloy retained the deformation texture even after recrystallization. At ^1/3 time law was found to hold for the grain growth over most of the grain sizevs time curve. The values of the activation energy for grain boundary migration were 25.2 Kcal/mole for the Ti-7.4 at. pct Al alloy and 29 Kcal/mole for the Ti-15.2 at. pct Mo alloy. These are similar to those for diffusion of Al and Mo in titanium, indicating that the diffusion of these substitutional elements controls the rate of boundary migration in these alloys. This paper is based on a presentation made at a symposium on “Recovery, Recrystallization and Grain Growth in Materials” held at the Chicago meeting of The Metallurgical Society of AIME, October 1977, under the sponsorship of the Physical Metallurgy Committee.     

Parasitic compensated switched capacitor circuits

A parasitic-insensitive switched capacitor circuit is presented which can functionally replace the `toggle-switched? capacitor. Its properties are established via an inverting integrator application. A related parasitic-insensitive realisation is also shown for a noninverting integrator, which can provide a 3/2 clock period transmission delay.     

Vibration of plates immersed in hot fluids

The vibration of structures immersed in water has been studied by Lamb and others. The influence of thermal stresses on the vibration characteristics of plates has been investigated and reported by several researchers. The work reported here deals with the determination of natural frequencies of plates immersed in water and subjected to six types of temperature distributions. The analysis is based on finite element method. A comment on thermal buckling of plates immersed in water is also reported.