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Showing papers by "Applied Science Private University published in 1988"


Journal ArticleDOI
01 Sep 1988-Spine
TL;DR: The determination of a single extension to flexion IAR may be of more value clinically, to which end this study provides essential normative data and invalidates the notion that plotting centrodes might be of diagnostic value in recognizing mechanical disorders.
Abstract: Lateral radiographs of ten normal individuals were studied to determine the location of the instantaneous axis of rotation (IAR) of every lumbar vertebra for the movements of flexion and extension from the upright position and flexion from the fully extended position; and errors involved in the technique were quantified to establish confidence limits for the results of the calculations. The distribution of the IARs was found to fall within a small range from the mean location at each level, particularly for the movement of flexion from the extended position. Within-observer and between-observer errors occurred in tracing and superimposing radiographs and marking x and y coordinates. Unacceptably large errors occur when the movement of the joint is less than 5 degrees, and only the IAR for flexion from extension can be plotted with acceptable confidence. This result invalidates the notion that plotting centrodes may be of diagnostic value in recognizing mechanical disorders. The determination of a single extension to flexion IAR may be of more value clinically, to which end this study provides essential normative data.

300 citations


Journal ArticleDOI
TL;DR: In this paper, the growth of losses, secondary kinetic energy, and streamwise vorticity have been studied in a high turning rotor cascade and negative vorticities associated with the passage vortex agreed well with predictions of classical secondary flow theory in the early part of the blade passage.
Abstract: The growth of losses, secondary kinetic energy, and streamwise vorticity have been studied in a high turning rotor cascade. Negative vorticity associated with the passage vortex agreed well with predictions of classical secondary flow theory in the early part of the blade passage. However, toward the exit, the distortion of the flow by the secondary velocities rendered the predictions inaccurate. Areas of positive vorticity were associated with the feeding of loss into the bulk flow and have been related to separation lines observed by surface flow visualization.

131 citations


Journal ArticleDOI
TL;DR: In this paper, a diagenetic rank factor was applied to peak shear strength and slake durability of mudrocks excavated from UK coal mines, and a tentative fully weathered effective stress peak strength for the weakest clays was deduced to be φ′ = 22°( c ′ = 0).
Abstract: British Coal Measures mudrocks are dominantly non-marine, mature sediments with a high average clay minerals content of over 75%. A geological classification based on quartz content does not differentiate the dominant durable mudrocks from the non-durable types and overconsolidated clays in the formation. A uniaxial compressive strength greater than 3.6MN/m 2 with a three cycle slake durability value of over 60% is suggested as an appropriate division between durable and non-durable mudrocks of this age. Physical breakdown, which acts as a control on chemical weathering triggered by pyrite oxidation, is considered to be governed by incidence of sedimentary structures, slaking and expandable mixed-layer clay content. Shear strength reduction during post-glacial weathering can be significant. A tentative fully weathered effective stress peak strength for the weakest mudrocks and clays is deduced to be φ′ = 22°( c ′ = 0). Colliery tip investigations indicate that chemical weathering effects on the shear strength of the mudrocks are small. A diagenetic rank factor applies both to peak shear strength and slake durability of mudrocks excavated from UK coal mines.

94 citations


Journal ArticleDOI
01 Jul 1988
TL;DR: Tests in the Durham hip function simulator show that the friction in these joints is up to an order of magnitude lower than in currently used prostheses, and because this is due to complete separation of the rubbing surfaces, wear ought to be vastly reduced.
Abstract: A new generation of hip replacements has been designed incorporating compliant layers to promote fluid film lubrication when the joints are implanted in patients. Tests in the Durham hip function simulator show that the friction in these joints is up to an order of magnitude lower than in currently used prostheses, and because this is due to complete separation of the rubbing surfaces, wear ought to be vastly reduced.Experiments have shown that the best results are achieved with compliant surfaces of hardness between 4 and 8 N/mm2. Such surfaces produce coefficients of friction of the order of 5 × 10-3.

74 citations


Journal ArticleDOI
TL;DR: In this paper, surface plasmon resonance is used to investigate the interaction between nitrogen dioxide and Langmuir-Blodgett films of a tetra-4-tert-butylphthalocyanine containing silicon.

66 citations


Book ChapterDOI
TL;DR: In this paper, a combined theoretical and laboratory study of the formation of shear bands in triaxial compression and plane strain compression is presented. But the results of the study are limited to the case of monotonic loading.
Abstract: This paper presents the results of a combined theoretical and laboratory study of the formation of shear bands in triaxial compression, triaxial extension, and plane strain compression. The principal finding is that shearbands are initiated more easily under plane strain than under axially symmetric conditions of the triaxial test. The triaxial compression test is most resistant to shear banding, although the theory tends to overestimate the stability of this test. The lack of agreement between the theory and experiment requires a reassessment of the suitability of isotropic hardening laws even for monotonic loading.

65 citations


Journal ArticleDOI
TL;DR: An experimental study of the lubrication mechanisms existing in prototype artificial hip joints which have compliant surface linings, has shown that for a lining with a hardness of about 4N/mm2, fluid film lubrication can be achieved even with the low viscosity synovial fluid present in diseased joints after surgery.
Abstract: An experimental study of the lubrication mechanisms existing in prototype artificial hip joints which have compliant surface linings, has shown that for a lining with a hardness of about 4N/mm2, fluid film lubrication can be achieved even with the low viscosity synovial fluid present in diseased joints after surgery. In tests, a synthetic lubricant was used in place of the synovial fluid. The best results seem to be produced with a 2 mm thick layer.

49 citations


Journal ArticleDOI
TL;DR: In this article, a review of spray pyrolysis, screen printing, and electrodeposition techniques for solar cells is presented, including the historical background and general aspects, up-to-date description of the status of materials compatible with the deposition techniques and structural, electrical and optical properties of deposited thin/thick films.

43 citations


Journal ArticleDOI
TL;DR: In this article, the preparation and characterization of LB films of 4-hexadecanoyltetrathiafulvalene (HDTTF) derivatives with one long hydrophobic chain have been discussed.

43 citations


Journal ArticleDOI
TL;DR: In this paper, the structural defects present in large single crystals of CdTe grown at the same temperature by two different vapour phase techniques have been investigated using a range of techniques including TEM, SEM, EBIC, EDX and chemical etching.

39 citations


Journal ArticleDOI
TL;DR: In this article, the variation in bandgap energy with composition was determined for single crystals of ZnxCd1-xSe at 300 and 90 K Au-Znxcd1xSe (x <045) diodes, and the dependence of barrier height and uncompensated donor density on composition was investigated.

Journal ArticleDOI
TL;DR: In this article, the effect of AI additions on the electrical behavior of positive temperature coefficient of resistance (PTCR) BaTiO3 ceramic sintered in air at temperatures ranging between 1220 and 1400° C have been investigated.
Abstract: The effect of AI additions on the electrical behaviour of positive temperature coefficient of resistance (PTCR) BaTiO3 ceramic sintered in air at temperatures ranging between 1220 and 1400° C have been investigated. Two batches of material, both showing a PTCR effect, were prepared identically except that additions of AI2O3 (0.55 mol %) were made to one of them. It has been confirmed that the presence of aluminium results in an increase in the temperature at which the maximum resistivity, ϱmax, occurs as well as reducing the sintering temperature, in the presence of silicon, to 1240° C. Additionally, direct comparisons between the two materials have demonstrated that such additions result in an increase of ∼ 100% in the minimum resistivity, ϱmin, at sintering temperatures beyond 1280° C. A similar increase in ϱmax for sintering temperatures below 1360° C and a five-fold reduction in the ratio of ϱmax/ϱmin in samples sintered above 1320° C have also been attributed to the presence of aluminium. It was further found that aluminium increases the average grain size by ∼ 30% and promotes the formation of a liquid phase.

Journal ArticleDOI
TL;DR: In this article, the effects of heating acid-amine alternate Langmuir-Blodgett films on the molecular arrangement and head group interactions have been studied in relation to pyroelectric activity.

Journal ArticleDOI
TL;DR: In this article, the deposition and characterization of Langmuir-Blodgett films of the ionophore valinomycin on single-crystal silicon and quartz substrates are described.

Journal ArticleDOI
TL;DR: Nos\'e's reversible mechanics is fully consistent with irreversible thermodynamics, in the way forecast by Prigogine, because the consistency follows from the formulation of new microscopic equations of motion.
Abstract: The microscopic mechanics discovered by Nos\'e, of which Gauss's isokinetic mechanics is a special case, makes it possible to simulate macroscopic irreversible nonequilibrium flows with purely reversible equations of motion. The Gauss-Nos\'e and Nos\'e-Hoover equations of motion explicitly include time-reversible momentum and energy reservoirs. Computer simulations of nonequilibrium steady-state systems described by Gauss-Nos\'e mechanics invariably evolve in such a way as to increase entropy. The corresponding phase-space distribution functions, which include reservoir degrees of freedom, collapse onto stable strange attractors. Hypothetical time-reversed motions, which would violate the second law of thermodynamics, cannot be observed for two reasons: First, such reversed motions would occupy zero volume in the phase space; second, they would be dynamically unstable. Thus, Nos\'e's reversible mechanics is fully consistent with irreversible thermodynamics, in the way forecast by Prigogine. That is, the consistency follows from the formulation of new microscopic equations of motion.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the origins of the pyroelectric effect in some alternate layer Langmuir-Blodgett (LB) films, and found that at low temperatures, the film behaves like a "free crystal" and showed a power law dependence on temperature.

Journal ArticleDOI
TL;DR: A structural comparison of epitaxial layers of (Hg, Cd)Te deposited onto CdTe/{111}B GaAs hybrid substrates and onto bulk {111}A CdTE substrates is also reported in this article.

Journal ArticleDOI
TL;DR: In this article, the authors present results for turbulence measurements that have been made using hot-wire anemometry in the endwall region of a high turning rotor blade cascade and show that the levels of turbulence are very high in the regions of the flowfield containing the passage vortex and its associated loss core.
Abstract: This paper presents results for turbulence measurements that have been made using hot-wire anemometry in the endwall region of a high turning rotor blade cascade. It is shown that the levels of turbulence are very high in the regions of the flowfield containing the passage vortex and its associated loss core. A comparison with the total pressure loss measurements illustrates the mechanisms of loss generation within the cascade. The growth of turbulent kinetic energy was much less than the growth of loss indicating significant viscous dissipation.

Journal ArticleDOI
TL;DR: In this article, a comparison of the structural properties of layers of CdTe and (Hg, Cd)Te grown on different substrates was made using the combined techniques of RHEED, SEM and cross-sectional TEM.

Book ChapterDOI
TL;DR: In this article, the drained stress-strain, volume change, and strength behaviors of sand with cross-anisotropic fabric were studied in triaxial compression tests, and the results for specimens with HID = 1.0 and 2.5, and lubricated ends were employed.
Abstract: The drained stress-strain, volume change, and strength behaviors of sand with cross-anisotropic fabric were studied in triaxial compression tests. Dense specimens with square cross-sections, height-to-diameter (HID) ratios of 1.0 and 2.5, and lubricated ends were employed. Specimens consisting of relatively long, flat sand grains were prepared with cross-anisotropic grain structure, whose axis of rotation was inclined at various orientations from vertical to horizontal. The specimen boundary conditions (flexible membrane and lubricated, rigid end plates) had different effects on the results for specimens with HID = 1.0 and 2.5. The specimens with HID = 2.5 exhibited distinct, but temporary drops in their prefailure stress-strain curves, and the friction angles changed in a consistent pattern over a range of 5.5°. In comparison, the specimens with HID = 1.0 showed more smooth stress-strain behavior, and their friction angles were essentially constant with very little effect of orientation.

Journal ArticleDOI
TL;DR: In this article, the results of calculations of Auger recombination rates in quantum wells, quantum well wires and quantum well spheres are described and reviewed, and the important physical factors influencing the Auger processes are identified and methods of reducing the recombination rate are considered.

Journal ArticleDOI
TL;DR: In this article, the epitaxial layers of ZnTe and CdTe superlattices have been grown by atmospheric pressure MOVPE on GaAs substrates and characterised by RHEED, SEM and TEM.

Journal ArticleDOI
TL;DR: In this paper, a multilayers of hexadecanoyltetrathiafulvalene (HDTTF) has been assembled on glass substrates; upon doping with iodine the films become highly insulating, but the conductivity increases with time following exposure, to reach a maximum value of 0.01 S cm −1 after a few hours.

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional underexpanded jet blowing tangentially over a cylindrical surface was studied experimentally and reported in a previous paper, where the inviscid core of the jet was calculated by the method of characteristics: the outer shear layer and surface boundary layer were ignored.

Journal ArticleDOI
TL;DR: In this paper, simple stereo-photographic techniques were employed to look in detail at over 150 shallow (i.e., shallow) images of the same scene. But the results were limited to a single image.
Abstract: Simple stereo-photographic techniques were employed to look in detail at over 150 shallow (

Journal ArticleDOI
01 Oct 1988

Journal ArticleDOI
TL;DR: In this article, the authors describe the automation and control of a'manual'synchromesh gearbox' in a form suitable for use in an electric or hybrid-electric vehicle.
Abstract: This paper describes the automation and control of a 'manual'synchromesh gearbox in a form suitable for use in an electric or hybrid-electric vehicle. Such a computer controlled transmission system allows full integration and control of the drive train leading to improved vehicle performance. The automation process is described, and a full description given, of the computer control algorithms necessary to ensure smooth and reliable operation of the transmission system. It is shown that an up-change can be achieved in 1.4 seconds and a down-change in 1.2 seconds. These times are shown to represent maximum gear change times and details of how they can be reduced substantially are discussed.

Journal ArticleDOI
TL;DR: In this paper, the estimation of ground movements caused by tunnelling through a granular soil overlain by a cohesive stratum is addressed both by a simple extension to the expressions leading to the normal distribution settlement profile and the consequent transverse inward movements, and also by a linear elastic finite element model.
Abstract: Empirical equations suitably defining surface movements caused by tunnelling in uniform soils are now well-established. Settlements transverse to the tunnel line are usually and conveniently described by a normal probability equation in terms of ground loss, V(m3/m) and of distance to the point of inflection, i (m). Vis dominantly a function of tunnelling method, and i has been expressed explicitly as a function of depth, but dependent upon whether the soil type is granular or cohesive. Little attention, however, has been given to the estimation of ground movements caused by tunnelling through a granular soil overlain by a cohesive stratum, and vice versa. The problem is addressed both by a simple extension to the expressions leading to the normal distribution settlement profile and the consequent transverse inward movements, and also by a linear elastic finite element model. Two well-documented case histories are assessed by the two methods of analysis and both give acceptable estimates of ground movement.

Journal ArticleDOI
TL;DR: Comparisons show the approximate analysis to be an extremely efficient and quite accurate computational scheme for the analysis of steady-state cold drawing processes.
Abstract: Approximate methods for analysing steady-state cold drawing processes in polymer forming are discussed. These methods are applied to both axisymmetric and plane-strain drawing. The cold drawing process is associated with steady-state neck propagation along the specimen. Modifications are introduced in the approximate steady-state analysis which reflect the neck initiation and localization phases prior to steady-state drawing. This is accomplished without resorting to an analysis of the entire load–deformation history of the process. Finite element results are also presented and compared with those of the proposed approximate analyses. These comparisons show the approximate analysis to be an extremely efficient and quite accurate computational scheme for the analysis of steady-state cold drawing processes.

Journal ArticleDOI
TL;DR: In this article, the results of a reliable electroplating method for the formation of the chalcocite (Cu 2 S) phase of copper sulphide on thin film CdS substrates are reported.