Showing papers by "Applied Science Private University published in 1981"
TL;DR: An approach is presented to the tripartite problem of modeling physical solids mathematically, representing the models in a computer, and using representations in geometric algorithms using representation-free (mathematical) models and functions.
Abstract: An approach is presented to the tripartite problem of modeling physical solids mathematically, representing the models in a computer, and using representations in geometric algorithms. Examples are primarily from the domain of manufacturing and design of discrete goods, but the results reported here have wider significance. Mathematical definitions can formalize many of our intuitions about three-dimensional (3-D) objects and operations on them. Representation-free (mathematical) models and functions allow formal properties to be defined for characterizing geometric representations. Three common representation schemes for 3-D objects are described briefly, along with some of their formal and informal properties. A rigorous, as opposed to ad hoc, approach to modeling has several advantages. Broadly, the conceptual complications and ambiguities which are endemic to ad hoc problem statements and solutions may be avoided by appealing to a precise mathematical semantics. Mathematical rigor is mandatory in applications such as automatic manufacturing in which correctness must be guaranteed and consistency and validity maintained.
43 citations
TL;DR: Effects of load and day-to-day variation on the autoregressive integrated moving average (ARIMA) model for signals from the medial deltoid muscle are discussed.
Abstract: In this communication we discuss effects of load and day-to-day variation on the autoregressive integrated moving average (ARIMA) model for signals from the medial deltoid muscle. The movement consisted of 15 successive 90°abduction-adductions under several loading conditions for two normal subjects. In one case, the measurements were repeated over two consecutive days.
35 citations
TL;DR: In this article, a torsion shear was used to study soil behavior during rotation of principal stress directions, and the results showed that the deformation of soil during large stress reversals and combinations of these conditions can be investigated in this apparatus.
Abstract: Laboratory studies of soil behavior during rotation of principal stress directions may be performed using a torsion shear apparatus. The requirements, construction, and operation principles for this apparatus are presented. The same confining pressure is applied to the inside and outside surfaces of a hollow cylindrical specimen. Both clockwise and counterclockwise shear stresses and vertical deviator stresses can be applied to the ends of the hollow cylinder. The entire setup is contained in a pressure cell, and the integrated loading system is located below the table which holds the cell. A variety of initial stress conditions may be used, and the behavior of soils during large stress reversals, as well as reorientation of principal stresses and combinations of these conditions, may be investigated in this apparatus. The loading system and the deformation measurement principles are described, and procedures for preparation of sand specimens are presented. The advantages and limitations of the torsion shear apparatus are discussed.
34 citations
TL;DR: In this article, a model for reactions taking place during the nitridation of high purity silicon powder compacts in the presence of furnace atmospheres contaminated by low partial pressures of water vapour is presented.
Abstract: High-purity silicon powder compacts have been nitrided in nitrogen atmospheres containing varying partial pressures of hydrogen. The accelerated nitridation rates observed are interpreted in terms of the interaction of the hydrogen with the natural oxide film on the surface of the silicon particles. A model is presented for reactions taking place during the nitridation of these compacts in the presence of furnace atmospheres contaminated by low partial pressures of water vapour.
29 citations
TL;DR: In this article, the glow discharge characteristics and sputtering behavior of a variety of metals (copper, nickel, aluminium, molybdenum, titanium and tantalum) were studied using a planar magnetron with a track of mean diameter 5.5 cm operated at power inputs of up to 100 W cm -2 in argon.
18 citations
TL;DR: A study of irradiation-induced precipitation (IIP) has been carried out on a series of palladium-based alloys containing tungsten, molybdenum, tantalum, and niobium, irradiated with 400-keV protons over the temperature range 65 to 750°C as discussed by the authors.
Abstract: A study of irradiation-induced precipitation (IIP) has been carried out on a series of palladium-based alloys containing tungsten, molybdenum, tantalum, and niobium, irradiated with 400-keV protons over the temperature range 65 to 750°C. IIP has been observed in the palladium-tungsten (Pd-W) alloy containing 10 and 18 atomic percent tungsten and in a Pd-10 atomic percent molybdenum alloy. In the Pd-W system, irradiation at temperatures of 300°C and above gives rise to a second phase tungsten precipitate associated with interstitial dislocation loops, while temperatures in excess of 200°C induce the formation of a tetragonal-ordered phase of the type Pd 8 W. IIP has been observed in the Pd-lOMo alloy, but only in specimens irradiated at 65°C. The irradiation gives rise to a molybdenum precipitate associated with interstitial dislocation loops, analogous to the occurrence of tungsten in the Pd-W alloy. IIP has not been observed in the palladium-tantalum and palladium-niobium systems at interstitial dislocation loops which form in the 200 to 400°C temperature range. The microstructures observed are described in detail and discussed in the light of recently proposed mechanisms of IIP. It is concluded that the IIP of tungsten and molybdenum at interstitial dislocation loops must occur as a consequence of strong interstitial solute atom binding, and that the observation of this phenomenon in the percent tungsten alloy represents the first clear-cut example of such binding in an alloy containing an oversized solute.
1 citations