Showing papers by "Applied Science Private University published in 1991"
TL;DR: In this article, a spin-coated polyaniline (PANi) was obtained with conductivities in the range 60-70 S/cm and anisotropy σ /σ ⊥ of up to 24.
115 citations
TL;DR: An algorithm is presented for constructing a Domain Delaunay triangulation (DDT) of an arbitrarily shaped, multiply-connected ( manifold or nonmanifold), planar domain that preserves the boundary of the given region and has properties identical to those of the standard Delaunays.
42 citations
TL;DR: In this article, a diagnostic manpower planning model for the construction industry has been developed, which considers both the environment and the factors that affect the demand for, and the supply of, regional labour.
Abstract: Developing countries are characterized by growing populations. Because of this and the initial low level of development, there is a need for infrastructures to support these populations. The industry that is most important in the developMent of the infrastructure (highways, utilities, industrial plants, etc.) is the construction industry. The construction industry in developing countries is characterized by a large pool of untrained, unskilled labour, and is unable to access its manpower needs. Therefore, a diagnostic manpower planning model for the construction industry has been developed. A diagnostic model was used because it considers both the environment and the factors that affect the demand for, and the supply of, regional labour. The types of data required for forecasting the demand and supply of regional labour, possible sources of data and possible manpower programmes are presented.
34 citations
01 Dec 1991
TL;DR: It was shown that some intervertebral joints do exhibit an increased ability to rotate when in some degree of sub-maximal flexion dependent on the morphology of the zygapophysial joints.
Abstract: This paper examined the mobility of intervertebral joints in axial rotation in a neutral and in two flexed positions. Torsion tests were conducted in vitro on specimens of isolated intervertebral joints in a rig specijically designed to apply torsion without imposing afixed axis. This permitted the specimens to rotate about their own mobile axis of axial rotation. In addition the specimens wereflexed about previously defined physiological axes of sagittalflexion in order to simulate movements as close as possible to those seen in life. It was shown that some intervertebral joints do exhibit an increased ability to rotate when in some degree of sub-maximalftexion dependent on the morphology of the zygapophysial joints. In full flexion axial rotation is limited, most probably by tightening of the posterior ligaments and zygapophysial joint capsules. This study lends evidence to the argument that torsion alone is insuficient to damage the intervertebral disc but a combination ofJexion and torsion will increase its vulnerability to injury.
34 citations
TL;DR: In this paper, low-temperature fluorescence studies of perylene in Langmuir-Blodgett films using fluorescence spectroscopy and a time-correlated single-photon counting technique are reported.
33 citations
28 citations
TL;DR: Currently the best candidate for a compliant material in hip replacement is the aliphatic polyether-urethane which maintains fluid-film lubrication.
25 citations
TL;DR: It was concluded that where spider venoms appear to possess necrogenic activity the most likely reason for this is contamination of the venoms with digestive tract secretions.
25 citations
TL;DR: In this paper the film deposition process is briefly reviewed and examples of multilayers incorporating biological molecules are presented and possible applications for such films in sensing structures are briefly discussed.
23 citations
TL;DR: This first report investigates the wear resistance of XLPE against itself, because for certain joints, such as the metacarpo-phalangeal joint, the material may have a high enough wear resistance to allow both bearing surfaces to be made from it.
20 citations
TL;DR: In this paper, a single component laser Doppler technique was used, and by taking several orientations at a given point, values of the three mean velocities and five of the six Reynolds stresses were obtained.
TL;DR: In this paper, the authors measured optical and electrical anisotropy in uniaxially stretch aligned polyaniline films and showed that these films closely resemble metallic polyacetylene.
TL;DR: In this paper, the concepts of suction and fabric are outlined, and their role in controlling the behaviour of road construction materials is illustrated by a fundamental laboratory study of a lateritic gravel and two calcrete gravels.
Abstract: Naturally-occurring road construction materials generally contain a greater amount of fines, and the fines have a higher plasticity than traditional materials such as a crushed rock aggregates. This makes their behaviour more difficult to understand and predict since soil suction and fabric become important controlling factors. The concepts of suction and fabric are outlined, and their role in controlling the behaviour of road construction materials is illustrated by a fundamental laboratory study of a lateritic gravel and two calcrete gravels. These materials have successfully been used as road base construction materials in low-volume bituminous-surfaced roads in Kenya and Botswana. It is concluded that the presence of fines can be an advantage, since they allow significant suctions to develop and also reduce the permeability.
TL;DR: In this article, a joint element is used to consider the rigid kinematic motion, elastic shear, and bending deformations of beam-column panel zone regions, which results in drifts values that were significantly larger than the usual rigid point joint assumption.
TL;DR: Inhibition of protein synthesis in hepatocytes from iron-loaded rats was primarily due to impaired amino acid uptake by these cells, and may be relevant for the development of hepatic fibrosis in patients with genetic hemochromatosis who consume excess ethanol.
TL;DR: In this paper, the chemical nature of samples of dicadmium stannate (Cd{sub 2}SnO{sub 4}) in the as-fired, electrochemically reduced, and reoxidized states was investigated.
Abstract: X-ray photoelectron spectroscopy (XPS) has been employed to investigate the chemical nature of samples of dicadmium stannate (Cd{sub 2}SnO{sub 4}) in the as-fired, electrochemically reduced, and reoxidized states. The reduction of Cd{sub 2}SnO{sub 4} was found to be associated with a dramatic color change from bright yellow to dark green, a phenomenon commonly known as the electrochromic effect. Both quantitative XPS results and binding energy measurements proved that, upon exposure of the reduced ceramic bodies to air, the Sn{sup 2+} to Sn{sup 4+} transition readily took place to produce the intermediate compound, Cd{sub 2}SnO{sub 3} with divalent tin. Prolonged exposure to the atmosphere did not result in further progress of reoxidation extending to monovalent cadmium. However, complete reoxidation of the reduced samples was possible by annealing in air at 350{degrees}C for a short period of time, e.g., 3 h by which the original features of the as-fired state such as color and electrical conductivity were restored. The results also showed that reoxidized samples at high temperature assume the same XPS characteristics as those of as-fired ceramics.
TL;DR: In this paper, thin films of CdTe have been deposited by MOVPE at 325°C onto the opposite polar faces of {0001} and { 0 1 1 ¯ 6 } oriented CdS single crystal substrates.
TL;DR: In this paper, the reflection high energy electron diffraction (RHEED) specular intensity during growth of the superconducting oxides was found to indicate that the growth of oxides occurs in monomolecular layer by monomeric layer mode, which made it possible to form a one unitcell layer and artificial superlattices as designed.
Abstract: We have found oscillations in the reflection high energy electron diffraction (RHEED) specular intensity during growth of the superconducting oxides, indicating that the growth of the oxides occurs in monomolecular layer by monomolecular layer mode. The film thickness has been exactly controlled by monitoring the RHEED oscillations which make it possible to form a one unit-cell layer and artificial superlattices as designed. The isolated ultrathin YBa 2 Cu 3 O 7−x (YBCO) films sandwiched in between PrBa 2 Cu 3 O 7−x (PrBCO) layers were prepared by the growth interrupt technique using the RHEED intensity oscillations. A one unit-cell YBCO layer has a superconducting transition with onset temperature at 70K and zero resistance at 30K. The overlayer of PrBCO was required to give the underlying one unit-cell YBCO superconductivity. The resistive transition for one unit-cell YBCO layer and the YBCO (one unit cell) / PrBCO (one unit cell) superlattice was independent of the magnetic field up to 10T applied parallel to the CuO 2 layers.
TL;DR: In this article, the analysis of a group of foundation piles under horizontal load is difficult because the system is strongly three-dimensional in nature and the materials of the piles and of the soil have very different stiffness properties.
TL;DR: In this paper, a study of Langmuir-Blodgett films of the 1:1 charge transfer salt N -octadecylpyridinium-tetracyanoquinodimethane using X-ray photoelectron spectroscopy is reported.
TL;DR: The magneto-tunneling effect was investigated in GaAsAlGaAs double barrier resonant tunneling devices in pulsed high magnetic fiels up to 40T applied parallel and perpendicular (B⊥) to the barrier layers.
TL;DR: In this paper, a feature-based analysis of sheet metal pans is presented, which is the basis for a GT coding system, which assists the design engineer in coding a part based on its features.
Abstract: SUMMARY Group technology (GT) is widely considered the bridge between design and production. This paper presents a feature-based analysis of sheet metal pans. This analysis is the basis for a GT coding system. A knowledge-based system was developed to assist the design engineer in coding a part based on its features.
TL;DR: In this article, the dielectric properties of some glass-ceramic-on-metal substrates were determined over the frequency range 500 Hz to 5 MHz using a.c. bridge techniques.
Abstract: The dielectric properties of some glass-ceramic-on-metal substrates have been determined over the frequency range 500 Hz to 5 MHz using a.c. bridge techniques. The substrates consisted of cordierite-based glass-ceramics screen printed on molybdenum. For glass layers of thickness greater than 100 μm both the permittivity, e′ and the dielectric loss, e″, are frequency independent over this frequency range at room temperature giving the value of e′=6.5 and tan δ=8×10−3; the room-temperature data are consistent with the universal law of dielectric response. The variation of permittivity with temperature has also been examined and, below 120 °C, the temperature coefficient [(e′−1) (e′+2)]−1 (∂e′/∂T)p, was found to be 1.3×10−5 K−1. The results are compared with those previously reported for Al2O3 and AIN substrates.
TL;DR: In this article, the authors extended the inductance probe technique for determining superconducting properties to include monitoring the Q-factor (Q) of the coil, with and without a superconductor present, as a function of temperature.
TL;DR: Ecological strategies designed to negate previously documented problems in the application of microbial EOR have been shown to be effective in laboratory experiments and field trials and overcoming environmental extremes and developing persistence of beneficial organisms have been given special attention.
Abstract: Microorganisms inhabiting petroleum-bearing formations or introduced into subterranean environments are subject to extremes of redox potential, pH, salinity, temperature, pressure, ecological pressure, geochemistry, and energy and nutrient availability. Successful microbial EOR requires the selection, injection, dispersion, metabolism and persistence of organisms with properties that facilitate the release of residual oil and the co-injection of growth effective nutrients into the extreme environments which characterize petroleum reservoirs. Ecological strategies designed to negate previously documented problems in the application of microbial EOR have been shown to be effective in laboratory experiments and field trials. Overcoming environmental extremes and developing persistence of beneficial organisms have been given special attention. The laboratory procedures, equipment and strategies used to develop successful field applications of biological stimulation of oil production (BOS) will be presented.
TL;DR: In this paper, the steering control system of an experimental autonomous vehicle operating in a pre-defined and structured environment is described, and a method of steering control is formulated which relates second-order criteria, such as rise time and damping factor, to the parameters of the control system.
Abstract: Experimental results relating to the steering control system of an experimental autonomous vehicle operating in a pre-defined and structured environment are presented. A method of steering control is formulated which relates second-order criteria, such as rise time and damping factor, to the parameters of the control system. With the control system described, the vehicle can track a path of constant heading with very little steady-state error and, if the control parameters are chosen in the correct ratio, it will respond in a critically damped fashion to the step disturbances which are generated by position corrections. For a curved path, demand curvature is treated as an input to the system in order to eliminate steady-state offset errors in tracking. In order to make the vehicle's performance independent of velocity, control parameters are derived as simple functions of velocity. This has the effect of allowing the vehicle to manoeuvre more tightly at lower speeds, and makes use of the increased availab...
22 May 1991
TL;DR: The results obtained show that good-quality solutions can be expected from simple heuristic methods with minimum scheduling overhead, and more advanced heuristic policies demonstrate particular promise for fast near-optimal re-allocation of processing resources in real-time audio processing applications.
Abstract: When implemented digitally, large-scale audio processing systems require the realisation of highly parallel architectures. Task scheduling strategies are necessary to distribute the processing algorithms required-termed the taskforce-across such architectures. The results obtained show that good-quality solutions can be expected from simple heuristic methods with minimum scheduling overhead. More advanced heuristic policies demonstrate particular promise for fast near-optimal re-allocation of processing resources in real-time audio processing applications.<
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01 Jan 1991
TL;DR: In this paper, the MOVPE growth of CdTe and subsequently ZnTe onto n-type single crystal (0001) CdS substrates was investigated and the fill factor of devices formed was low −0.33 mainly due to the resistive p-ZnTe layer.
Abstract: Epitaxial ZnTe/CdTe/CdS p-i-n heterostructures have been fabricated by the MOVPE growth of CdTe and subsequently ZnTe onto n-type single crystal (0001) CdS substrates. Analysis of the current-voltage characteristics suggests that the electrical transport across the junctions is dominated by a multi-step tunnelling process. Preliminary photovoltaic measurements without optimisation of the contact geometries gave open circuit voltages of up to 0.1 V and short circuit currents of 5 mA cm−2. The fill factor of devices formed was low −0.33 mainly due to the highly resistive p-ZnTe layer.