Penetration Dynamics of Earth Penetration Warhead into Composite Target Media

Attempts have been made to develop a suitable computer code that can find solutions to the axi-symmetric penetration of an Earth Penetrating Warhead yielding complete space-time histories of the resistive force offered by the target medium. The consequent warhead deceleration and velocity reduction, the resulting axial compressive stress developed in warhead casing as the penetration process progresses into the composite target media consisting of hard concrete of specified thickness followed by earth soil have been discussed

Optimal Folding of Data Flow Graphs based on Finite Projective Geometry using Lattice Embedding

A number of computations exist, especially in area of error-control coding and matrix computations, whose underlying data flow graphs are based on finite projective-geometry(PG) based balanced bipartite graphs. Many of these applications are actively being researched upon. Almost all these applications need bipartite graphs of the order of tens of thousands in practice, whose nodes represent parallel computations. To reduce its implementation cost, reducing amount of system/hardware resources during design is an important engineering objective. In this context, we present a scheme to reduce resource utilization when performing computations derived from PG-based graphs. In a fully parallel design based on PG concepts, the number of processing units is equal to the number of vertices, each performing an atomic computation. To reduce the number of processing units used for implementation, we present an easy way of partitioning the vertex set. Each block of partition is then assigned to a processing unit. A processing unit performs the computations corresponding to the vertices in the block assigned to it in a sequential fashion, thus creating the effect of folding the overall computation. These blocks have certain symmetric properties that enable us to develop a conflict-free schedule. The scheme achieves the best possible throughput, in lack of any overhead of shuffling data across memories while scheduling another computation on the same processing unit. This paper reports two folding schemes, which are based on same lattice embedding approach, based on partitioning. We first provide a scheme for a projective space of dimension five, and the corresponding schedules. Both the folding schemes that we present have been verified by both simulation and hardware prototyping for different applications. We later generalize this scheme to arbitrary projective spaces.Comment: 31 pages, to be submitted to some discrete mathematics journa

Transistor-Based Studies of Heavy Dop-ing Effects in n-GaAs

The n2ieDp product (where n2ie is the np product and Dp is the minority hole mobility) in heavily doped n‐GaAs has been measured by electrical characterization of p‐n‐p GaAs homojunction transistors with base dopings ranging from approximately 1×1017 to 9×1018 cm−3. The measured n2ieDp product decreases as the doping density increases. These results suggest that nie is roughly constant with doping density, in sharp contrast to the large increase observed for p‐type GaAs. This work shows that when designing GaAs bipolar devices, it is important to consider the large difference in effective band gap between n+ and p+ regions

Characterization of photon recycling in thin crystalline GaAs light emitting diodes

Gallium arsenide light emitting diodes (LEDs) were fabricated using molecular beam epitaxial films on GaAs substrates and removed by epitaxial lift-off (ELO). Lifted off devices were then mounted on a Si wafer using a Pd/Au/Cr contact layer, which also served as a back surface reflector. Devices were characterized by electrical and optical measurements, and the results for devices on the GaAs substrate were compared to those for EL0 devices. EL0 LEDs coated with a ZnS/MgF2 antireflection coating exhibited an optical output that was up to six times that of LEDs on GaAs substrates. At the same time, the measured current-voltage characteristics of the EL0 devices displayed a lower IZ = 1 current component. EL0 LEDs with efficiencies up to 12.5% were realized. We attribute these results to photon recycIing enhanced by the back-surface reflector in the EL0 LEDs. The luminescence versus current and current versus voltage characteristics of the LEDs were analyzed to obtain the nonradiative minority carrier lifetimes and the photon recycling factors. The results demonstrate that the measured characteristics are well described by photon recycling theory. EL0 LEDs may prove useful for characterizing recombination processes in LEDs, and thin-crystalline structures could provide substantial efficiency enhancements for LEDs and solar cells

A comparative study of combined spinal epidural anaesthesia and general anaesthesia in patients undergoing percutaneous nephrolithotomy

Background: Our primary aim was to study the efficacy, safety, hemodynamic stability, postoperative pain relief, and complication with combined spinal epidural anaesthesia (CSE) and to compare it with general anaesthesia (GA) for percutaneous nephrolithotomy (PCNL).  Methods: The present study was a prospective, randomized, open, controlled trial to compare the effects of CSE and GA in patients undergoing PCNL. Study was carried out in 100 adult patients, who were randomly divided into two groups of 50 each, Group GA and Group CSE. Post-operative pain relief and amount rescue analgesia required were noted. Postoperatively samples were collected for haemoglobin and arterial blood gases. Incidence of complications were noted and compared among both the groups.Results: Mean arterial pressure in CSE group was less compared to GA group during the procedure. 30 % patients in group GA required first rescue analgesia within first hour of completion of surgery whereas no patient in group CSE required analgesia within first hour indicating better pain relief in CSE group. Mean haemoglobin and the fall in haemoglobin between the groups were comparable. 48.0% of the cases among GA group and 14.0% of the cases among CSE group had postoperative nausea and vomiting. Mean pH in GA group was 7.33±0.05 and in CSE group was 7.36±0.04. There was one case of hydrothorax post operatively.Conclusions: We conclude that CSE is a safe alternative to GA for PCNL with better pain relief, less PONV. Hypotension due to sympathetic blockade is always a possibility

Computer-interpretable guidelines: electronic tools to enhance the utility of thyroid nodule clinical practice guidelines and risk stratification tools

Clinicians seeking guidance for evaluating and managing thyroid nodules currently have several resources. The principal ones are narrative clinical guidelines and clinical risk calculators. This paper will review the strengths and weaknesses of both. The paper will introduce a concept of computer interpretable guideline, a novel way of transforming narrative guidelines in to a clinical decision support tool that can provide patient specific recommendations at the point of care. The paper then describes an experience of developing an interactive web based computer interpretable guideline for thyroid nodule management, called Thyroid Nodule Management App (TNAPP). The advantages of this approach and the potential barriers for widespread adaptation are discussed

Very low resistance nonalloyed ohmic contacts using low-temperature molecular beam epitaxy of GaAs

Ex situ nonalloyed ohmic contacts were made to n- and p‐type GaAs using low‐temperature molecular beam epitaxy. For n‐type GaAs, Ag, and Ti/Au nonalloyed contacts displayed specific contact resistitivities of mid 10-7 ohm cm2. For p‐type GaAs, nonalloyed Ti/Au contacts with specific contact resistivities of about 10-7 ohm cm2 were obtained

Separation and liquid-liquid extraction of thorium(IV) as sulfate complex withsynergistic mixture of N-n-octylaniline and trioctylamine as an extractant

ABSTRACT Extraction of thorium from aqueous sulphuric acid medium with a synergistic mixture of N-n-octylaniline and trioctylamine (TOA) in xylene is reported in this paper. The effects of varying the concentration of sulphuric acid, N-n-octylaniline and trioctylamine on the distribution ratio of Thorium have been studied. Based on the results obtained, the possible extraction mechanism has been discussed. The determination of thorium and its separation from synthetic mixture has been suggested. The method has been extended to the analysis of thorium in monazite sand and gas mantle