The transmission or scattering of elastic waves by an inhomogeneity of simple geometry: A comparison of theories

The extended method of equivalent inclusion developed is applied to study the specific wave problems of the transmission of elastic waves in an infinite medium containing a layer of inhomogeneity, and of the scattering of elastic waves in an infinite medium containing a perfect spherical inhomogeneity. The eigenstrains are expanded as a geometric series and the method of integration for the inhomogeneous Helmholtz operator given by Fu and Mura is adopted. The results obtained by using a limited number of terms in the eigenstrain expansion are compared with exact solutions for the layer problem and for a perfect sphere. Two parameters are singled out for this comparison: the ratio of elastic moduli, and the ratio of the mass densities. General trends for three different situations are shown

Data catalog series for space science and applications flight missions. Volume 4A: Descriptions of meteorological and terrestrial applications spacecraft and investigations

The National Space Science Data Center (NSSDC) provides data from and information about space science and applications flight investigations in support of additional studies beyond those performed as the principal part of any flight mission. The Earth-orbiting spacecraft for investigations of the earth and its atmosphere is discussed. Geodetic tracking data are included in this category. The principal subject areas presented are meteorology and earth resources survey, and the spacecraft selection is made according to those subjects. All experiments on board the spacecraft are described. No attempt is made to reference investigations that are related to the above disciplines, but that are described in other volumes of this series

Pass-Through And The Prediction Of Merger Price Effects

We use Monte Carlo experiments to study how pass-through can improve merger price predictions, focusing on the first order approximation (FOA) proposed in Jaffe and Weyl [2013]. FOA addresses the functional form misspecification that can exist in standard merger simulations. We find that the predictions of FOA are tightly distributed around the true price effects if pass-through is precise, but that measurement error in pass-through diminishes accuracy. As a comparison to FOA, we also study a methodology that uses pass-through to select among functional forms for use in simulation. This alternative also increases accuracy relative to standard merger simulation and proves more robust to measurement error

Upward Pricing Pressure As A Predictor Of Merger Price Effects

We use Monte Carlo experiments to evaluate whether “upward pricing pressure” (UPP) accurately predicts the price effects of mergers, motivated by the observation that UPP is a restricted form of the first order approximation derived in Jaffe and Weyl (2013). Results indicate that UPP is quite accurate with standard log-concave demand systems, but understates price effects if demand exhibits greater convexity. Prediction error does not systematically exceed that of misspecified simulation models, nor is it much greater than that of correctly-specified models simulated with imprecise demand elasticities. The results also support that UPP provides accurate screens for anticompetitive mergers

Fundamentals of microcrack nucleation mechanics

A foundation for ultrasonic evaluation of microcrack nucleation mechanics is identified in order to establish a basis for correlations between plane strain fracture toughness and ultrasonic factors through the interaction of elastic waves with material microstructures. Since microcracking is the origin of (brittle) fracture, it is appropriate to consider the role of stress waves in the dynamics of microcracking. Therefore, the following topics are discussed: (1) microstress distributions with typical microstructural defects located in the stress field; (2) elastic wave scattering from various idealized defects; and (3) dynamic effective-properties of media with randomly distributed inhomogeneities

Strategic Decision Support For Information Protection: A Facilitation Framework For Small And Medium Enterprises

Information security seriously concerns Corporate America but the soaring cost on protecting information assets raises equal concerns. These concerns appear to be more threatening to the small and medium enterprises (SMEs) as the percentage of their IT budgets spent on information security protection sharply surpasses those percentages budgeted by large enterprises. In light of these concerns, we propose an integrated and attainable framework that could heuristically promote strategic decision thinking on protecting information assets for the SMEs.  In comparison to other approaches that aim at reaching an optimal decision through complex mathematical models, our framework requires no such computations. The goal of our approach is to help a SME reach such decisions with a framework that takes business, technological and managerial issues into account. The proposed framework fosters strategic thinking of security issues with simple and practical steps to achieve a balanced, consistent, and efficient protection with total involvement from all stakeholders of the information assets that need to be protected

KINEMATIC ANALYSIS OF THE VOLLEYBALL BACK ROW JUMP SPIKE

The purpose of this study was to identify and describe the kinematic characteristics of the volleyball one-foot and two-foot back row jump spikes. Eight elite male players participated in this study. Two Peak high-speed cameras (120Hz) were synchronised to record the spiking action. The results indicated that the one-foot spike had a greater approach, centre of mass (CM) velocity, a greater horizontal CM velocity at takeoff and a shorter spiking time than that of the two-foot spike. The swing leg of the one-foot jump spike also played an important role in contributing fo~wardm omentum to the jump during the support phase. This study provides information for coaches in teaching the volleyball one-foot and two-foot back row jump spike

Antisite effect on ferromagnetism in (Ga,Mn)As

We study the Curie temperature and hole density of (Ga,Mn)As while systematically varying the As-antisite density. Hole compensation by As-antisites limits the Curie temperature and can completely quench long-range ferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by molecular beam epitaxy without substrate rotation in order to smoothly vary the As to Ga flux ratio across a single wafer. This technique allows for a systematic study of the effect of As stoichiometry on the structural, electronic, and magnetic properties of (Ga,Mn)As. For concentrations less than 1.5% Mn, a strong deviation from Tc ~ p^0.33 is observed. Our results emphasize that proper control of As-antisite compensation is critical for controlling the Curie temperatures in (Ga,Mn)As at the low doping limit.Comment: 10 pages, 7 figure

Modeling The Post-Burn-In Abnormal Base Current In Algaas/Gaas Heterojunction Bipolar Transistors

The base current of AlGaAs/GaAs heterojunction bipolar transistor subjected to a long burn-in test often exhibits an abnormal characteristic with an ideality factor of about 3, rather than a normal ideality factor between 1 and 2, in the midvoltage range, We develope an analytical model to investigate the physical mechanisms underlying such a characteristic. Consistent with the finding of an experimental work reported recently, our model calculations show that the recombination current in the base has an ideality factor of about 3 in the midvoltage range and that such a current is responsible for the observed abnormal base current in heterojunction bipolar transistor after a long burn-in test. Post-burn-in data measured from two different heterojunction bipolar transistors are also included in support of the model