Synthesis and characterization of bulk and thin film antimony-selenium phase change alloys

Phase change alloys have recently gained increasing attention due to their application in developing phase change random memory (PRAM) devices, as Flash memory based devices are rapidly approaching their technological limitations. The most dominant features of PRAM devices are its non-volatile nature, compatible with present day IC\u27s manufacturing process, high density, fast operation, low power consumption etc; Devices built on binary alloys such as Antimony - Selenium (SbSe) exhibit certain superior properties such as fast operation, reduced power consumption, economical etc. compared to that of ternary alloy (GST). In order to understand this behavior in detail, bulk SbxSe 100-x (40 ≤ x ≤ 70) alloys are synthesized and deposited as thin films on silicon (100) plane substrate. Series of experiments such as X-ray diffraction analysis (XRD), Energy dispersive X-ray diffraction (EDAX), Spectroscopic Ellipsometer, Hall test experiments are carried out to characterize both the bulk and thin films. EDAX experiments show the deviation between bulk and thin films compositions is less than 10%. Diffraction patterns of bulk exhibit orthorhombic structure, i.e., Sb2Se3 type where as thin films demonstrate amorphous behavior. Impact of annealing on thin films is studied by heating the films to 170°C under argon (Ar) ambience. Post annealing results of Sb40Se60 thin films show the crystal structure is orthorhombic and crystallization temperature (Tc) increases with increase in Sb content of the compound. Ellipsometry and Hall measurements of annealed films exhibit high refractive index (n), low extinction coefficient (k) and high carrier concentration with associated low carrier mobility. Further the conductivity of annealed Sb40Se60 thin films switches from p to n type

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was concentrated during motion up thrust ramps with estimated erosion rates of ~0.1 to 0.3 km/Myr. Local cooling ages of approximately 160–150 Ma may record a period of regional erosion, or alternatively an early phase of limited... (see full abstract in article)

Runner Identity and Sponsorship: Evaluating the Rock ‘n’ Roll Marathon

The economic value of participation sport has been reported to eclipse spectator sport significantly. However, scholars have acknowledged the relative lack of research on this important segment of the sport market. The purpose of this study was to analyze the relationship between runner identity and race sponsor effectiveness. Surveys were sent to participants in the Las Vegas Rock ‘n’ Roll Marathon. The survey was constructed to measure runner identity, and sponsor effectiveness as interpreted through rates of recognition, recall and purchase intention. Runners were divided into three groups based on their runner identity score. Of the predictive variables, only runner identity was a significant predictor of sponsor recognition and recall and one of two significant variables for purchase intention. The current study established runner identity as a unique construct and shows how runner identity is tied to measures that can be used by race organizers to attract or retain sponsors

Characterization and extent of expansive soils in the Las Vegas Valley

Expansive soils have been documented in the Las Vegas Valley for many years; however, the extent of these soils horizontally and vertically was relatively unknown. This study investigates the extent and expansivity of soils in the Las Vegas Valley. It is an attempt to present an empirical model predicting areas where expansive soils may be encountered. A correlation between swell test results and plasticity index was evaluated for two datasets, and results compare favorably with relationships established for other areas. Analyses were conducted to evaluate correlations between expansion potential and topographic slope, soil classification, and locations of subsidence-related faults and earth fissures. Results show that expansion potential generally increases with decreasing slope, finer grain-size and increasing plasticity. Over ninety-four percent by length of mapped subsidence-related faults are located within areas having some expansion potential. Eighty-eight percent of earth fissures are found in areas exhibiting moderate to critical expansion

Semi-active control techniques for shock isolation

In this thesis the problem of control of semi-active devices (MR damper, MR elastomer) for shock isolation systems are considered. Semi-active control systems combine the best features of both the passive and active control systems, offering the reliability of passive devices, yet maintaining the versatility and adaptability of fully active devices. First the question of stability and control of a two degree-of-freedom magnetorheological (MR) fluid damper shock isolation system is considered. It is shown that for any arbitrarily time varying input current, the system is absolutely stable. This explains the shock isolation capability of the MR damper system even with control laws clamped in an ad hock way to limit the control magnitude. Then a nonlinear inverse (feedback linearizing) control law and a nonlinear suboptimal control law based on the state-dependent Riccati equation (SDRE) method are designed for the shock isolation of the payload mass. For the inverse control law derivation, the inertial position of the payload is chosen as the controlled output variable. For the design via the SDRE method, constraint on the input current is introduced and a quadratic performance index is chosen for minimization. It is shown that in the closed-loop system the inverse and suboptimal control laws are effective in shock isolation of the payload mass; Secondly, the mathematical modeling and predictive control of a magnetorheological fluid damper system is considered. (Abstract shortened by UMI.)

Development of a safety analysis and an intersection infrastructure system

GIS and GPS technologies have found immense applications in the field of transportation engineering. Different features related to transportation safety are inventoried using these technologies. The databases so created serve as main source for safety analyses, decision making and reporting. Many different analyses tools are available to assist engineers, planners and policy makers in the process of improving transportation safety. GIS-based analyses tools provide tabular and graphic display, thereby expediting the analyses process and improving the spatial understanDing The advantages of such tools increase if they can be provided on the World Wide Web. One such software system that offers online analyses tool is the ArcIMS; This research is aimed at developing a GIS-based tool to inventory signalized intersection attributes. In addition, an internet based analyses system that utilizes the signalized intersection database and the crash database is developed. The tools provide number of choices to perform user-defined queries to generate specific results. The system is developed using Visual Basic .Net programming language. The applications developed here are demonstrated with the data available for the Las Vegas metropolitan area

The Persistent Southern Disadvantage in Us Early Life Mortality, 1965‒2014

Background: Recent studies of US adult mortality demonstrate a growing disadvantage among southern states. Few studies have examined long-term trends and geographic patterns in US early life (ages 1 to 24) mortality, ages at which key risk factors and causes of death are quite different than among adults. Objective: This article examines trends and variations in early life mortality rates across US states and census divisions. We assess whether those variations have changed over a 50-year time period and which causes of death contribute to contemporary geographic disparities. Methods: We calculate all-cause and cause-specific death rates using death certificate data from the Multiple Cause of Death files, combining public-use files from 1965‒2004 and restricted data with state geographic identifiers from 2005‒2014. State population (denominator) data come from US decennial censuses or intercensal estimates. Results: Results demonstrate a persistent mortality disadvantage for young people (ages 1 to 24) living in southern states over the last 50 years, particularly those located in the East South Central and West South Central divisions. Motor vehicle accidents and homicide by firearm account for most of the contemporary southern disadvantage in US early life mortality. Contribution: Our results illustrate that US children and youth living in the southern United States have long suffered from higher levels of mortality than children and youth living in other parts of the country. Our findings also suggest the contemporary southern disadvantage in US early life mortality could potentially be reduced with state-level policies designed to prevent deaths involving motor vehicles and firearms

Characterization of structural materials for applications in Hi(x) decomposition

Zr705 and Nb7.5Ta have been tested for evaluation of their metallurgical and corrosion properties for applications in nuclear hydrogen generation using an S-I cycle based on the HIx decomposition process. The results of tensile testing involving both alloys indicate that the tensile strength was gradually reduced with increasing temperature, as expected. Further, the ductility for both alloys was reduced at some critical temperatures, possibly due to the dynamic strain-aging effect. Zr705 did not exhibit cracking in acidic aqueous solutions, both under constant-load and self-loaded conditions. The stress-corrosion-cracking (SCC) tests of Zr705 in an acidic solution showed reduced true failure stress but enhanced ductility at elevated temperatures. With respect to the SCC susceptibility of Nb7.5Ta in an identical environment, slight change in failure strain was noted at different temperatures. The critical potentials determined in localized corrosion study became more active with increasing temperature. The application of anodic and cathodic potentials enhanced the cracking susceptibility of Zr705. Dimpled microstructures, characteristic of ductile failure, were observed in both materials

Cenozoic extension in the River Mountains and Frenchman Mountain, Southern Nevada

The River Mountains are the eroded remnants of a mid-Miocene stratovolcano complex located between Henderson, Nevada and western Lake Mead. This study addresses the tectonic and societal significance of (1) a 13.5-9 Ma initial stage and (2) a late-Pliocene(?)-present stage of extension. Multiple slip histories were recorded on NW-, N-, NE-, and E-striking conjugate fault sets, in addition to numerous orthorhombic faults. Multiple corrugations on the Saddle Island detachment (SID) during 13.5-9 Ma extension are interpreted to have produced localized zones of triaxial strain and orthorhombic faulting. Conjugate faults occurred where the SID was planar. The multiple kinematics suggest that 13.5-9 Ma tectonism in the River Mountains was controlled by transient slip gradients on the Las Vegas Valley shear zone and the Lake Mead fault system. Active faults of the second period of extension may impact present day Las Vegas. An earthquake rupturing the combined 38 km length of the Ithaca Avenue Fault-Frenchman Mountain Fault could produce a MW 6.9 +/- 0.3 earthquake