Impact damage of composite plates

A simple model to study low velocity transverse impact of thin plates made of fiber-reinforced composite material, in particular T300/5208 graphite-epoxy was discussed. This model predicts the coefficient of restitution, which is a measure of the energy absorbed by the target during an impact event. The model is constructed on the assumption that the plate is inextensible in the fiber direction and that the material is incompressible in the z-direction. Such a plate essentially deforms by shear, hence this model neglects bending deformations of the plate. The coefficient of restitution is predicted to increase with large interlaminar shear strength and low transverse shear modulus of the laminate. Predictions are compared with the test results of impacted circular and rectangular clamped plates. Experimentally measured values of the coefficient of restitution are found to agree with the predicted values within a reasonable error

Faster Algorithms for Weighted Recursive State Machines

Pushdown systems (PDSs) and recursive state machines (RSMs), which are linearly equivalent, are standard models for interprocedural analysis. Yet RSMs are more convenient as they (a) explicitly model function calls and returns, and (b) specify many natural parameters for algorithmic analysis, e.g., the number of entries and exits. We consider a general framework where RSM transitions are labeled from a semiring and path properties are algebraic with semiring operations, which can model, e.g., interprocedural reachability and dataflow analysis problems. Our main contributions are new algorithms for several fundamental problems. As compared to a direct translation of RSMs to PDSs and the best-known existing bounds of PDSs, our analysis algorithm improves the complexity for finite-height semirings (that subsumes reachability and standard dataflow properties). We further consider the problem of extracting distance values from the representation structures computed by our algorithm, and give efficient algorithms that distinguish the complexity of a one-time preprocessing from the complexity of each individual query. Another advantage of our algorithm is that our improvements carry over to the concurrent setting, where we improve the best-known complexity for the context-bounded analysis of concurrent RSMs. Finally, we provide a prototype implementation that gives a significant speed-up on several benchmarks from the SLAM/SDV project

Random matrices with external source and KP τ\tau functions

In this paper we prove that the partition function in the random matrix model with external source is a KP $\tau$ function.Comment: 12 pages, title change

Multi-year Water Allocation: A Policy Analysis for Groundwater Management and Conservation for Irrigated Agriculture

Heavy withdrawals from the most dependable source of groundwater in the Texas Panhandle, the Ogallala Aquifer, create an impending need for implementing water conservation policies. This study evaluates the policy option of multi-year water allocation coupled with water use restriction in four water deficit counties of Castro, Deafsmith, Parmer and Swisher over a sixty year planning horizon. Results indicate that the water use in the study area declines with progressive restriction rates accompanied by a substantial decrease in the net present value of net returns over sixty years and therefore it is important to analyze the socio-economic effects of implementing such a policy alternative.Multi-year allocation, Ogallala Aquifer, Texas Panhandle, Water conservation, Environmental Economics and Policy, Farm Management, Resource /Energy Economics and Policy,

Production Profitability of Ethanol from Alternative Feedstocks in the Texas Panhandle

The potential of three feedstocks: grain sorghum, sweet sorghum, and switchgrass for ethanol production in the top 26 counties of the Texas Panhandle Region is analyzed using yield and production costs of feedstock, processing cost of feedstock, final demand for ethanol, farm to wholesale marketing margin, and the derived demand price of feedstock. The calculated economic returns per acre of grain sorghum, sweet sorghum, and switchgrass are -$45.37, -$410.19, and -$150.17 respectively under irrigated condition and -$38.25, -$145.09, and -$29.04 respectively under dryland condition. The evaluation in this study demonstrates that ethanol production from grain sorghum, sweet sorghum, and switchgrass in the Texas Panhandle Region is not economically feasible given the current price for ethanol in Texas. This is consistent with the status of the ethanol industry in the Texas Panhandle.Ethanol production, Texas Panhandle, Grain sorghum, Sweet sorghum, and Switchgrass, Feedstock, Crop Production/Industries, Production Economics, Resource /Energy Economics and Policy, Q16, Q25, Q27, and Q42,

Evaluating Dryland Crop/Livestock System Alternatives for Risk Management under Declining Irrigation in the Texas Panhandle

Production budgets for dryland crop and crop/livestock systems are developed to estimate yields, costs and returns for dryland wheat and sorghum and for alternative dryland crop/livestock systems. A crop simulation model aids yield estimation. The yield and return distributions are used to estimate risk and relative risk for included alternatives.Relative Risk, Ogallala Aquifer, Crop-Livestock Systems, Wheat, Sorghum, Crop Production/Industries, Farm Management, Livestock Production/Industries, Production Economics, Productivity Analysis,

Wavelength Dependence of Transverse Mode Coupling With/Without E-Block of GaN Laser Cavity

Transverse mode wavelength dependence in the gallium nitride (GaN) laser cavity is a new topic. Modal analysis simulations are run to optimize the blue GaN-based laser diode with a wavelength of 400, 430, and 460 nm. It is shown that the optical confinement factor (OCF) has a strong dependence on wavelength of emission and electron-block (e-block) thickness. The OCF can be changed from 4.9% at a 460-nm wavelength to 7.6% at 400 nm, which is a 55% difference. The effect of adding an e-block layer of different widths is also investigated with results showing that an e-block layer can change optical confinement by 14% at 460 nm wavelength and 13% at 400 nm wavelength. The bottom n-GaN layer thickness is optimized between 0.1 and 7 μm. It is found that a thin buffer layer improves optical mode distribution by reducing the ghost mode

UNUSUAL PRESENTATION OF A PATIENT WITH GBL WITHDRAWL: A CASE REPORT

GBL (gamma-butyro-lactone) is converted to Gamma hydroxyl butyrate (GHB) in the body. GBL and GHB are available in liquid form and powder form. Once categorised under “legal highs”, these two are not associated with any dependence or withdrawal in animal studies. But there are case reports indicating their high dependence potential in humans. We here present a case of a 29 year old who came to the attention of psychiatric services with very bizarre presentation and needed a host of investigations and expert views from various medical disciplines. He was treated mainly symptomatically followed by a sudden dramatic recovery on the 11th day after presentation. GBL is getting popular as a recreational drug and its withdrawal should be seriously considered in the list of medical causes leading to Delirium

Climatic forcing before, during, and after the 8.2 Kyr B.P. global cooling event

This paper attempts at full characterization of the unique global 8.2 Kyr B.P. cooling event. Significant atmospheric cooling started during 9.5-8.5 Kyr B.P. when the Sun was extremely quiet during three periods of ~ 50-100 years. The flood of melt water in the N. Atlantic from glacial lakes during the demise of the Laurentide ice sheet, starting at ~ 8.5 Kyr B.P., adds to the atmospheric cooling. Climatic forcing events occurred at 8.5 Kyr B.P., at 8.2 Kyr B.P. and finally at 8.06 Kyr B.P., leading to concurrent increases or decreases in the atmospheric Δ 14C levels, completely consistent with the climatic forcing proposed here