Controlled Environmental Effects on Creep Test Data of Woven Fabric Webbings for Inflatable Space Modules

eveloping technologies for proposed lunar and Mars space exploration missions. Enhanced habitation sy g studied as potential habitats due to their inherent low mass and small launch volume. One goal of inflatable module research is quantification of the safe-life and end-of-life creep-strain spectrum. Full-scale pressurized inflatable modules are large, costly, and difficult to experimentally study. Therefore, material subcomponents are often studied as an alternative. An experimental thermally controlled long-term creep study of VectranTM webbings for application to inflatable modules is presented. Vectran fibers have high strength and low creep properties. High strength webbing materials are desirable for the load bearing restraint layer of inflatable modules because they are strong, flexible, and lightweight. Characterization of the creep behavior, safe-life, and end-of- life of webbing specimens will help quantify comparable life properties for inflatable modules. Several experimental multiple-year creep studies of webbing specimens in uncontrolled thermal environments have been conducted at NASA Langley Research Center. Experimental data obtained exhibits the classic creep-strain curve due to load, coupled with unique sinusoidal variation due to variation in temperature and humidity over daily and annual time periods. Results also have indicated that specimens fail within a year if the applied load is greater than 50 percent of the rated load. The primary goal of this study is to eliminate thermal effects from the creep data for a group of webbing specimens, and to allow uncontrolled thermal effects to influence the creep data of a second group of webbing specimens. Comparison of both sets of data will define how temperature influences creep data. A unique creep test facility was fabricated to facilitate the generation and comparison of the two sets of data. The facility consists of five creep test stands with an integrated heating and cooling system, and four creep test stands exposed to external environmental or ambient conditions. The facility contains displacement, temperature, humidity, and load sensors. Test specimens consist of one- inch wide, 48-inch long Vectran webbings rated at 12,500 pounds-per-inch. Experimental thermally controlled creep-strain data has been generated for two groups of webbing specimens. Applied load for all test stands was above 9000 lbs and greater than 50 percent of the rated load. Temperatures varied between 58F and 83F for the four test stands exposed to ambient conditions. Associated creep data exhibited the classic creep- strain profiles. The temperature was set to 72F for the five test stands in the controlled temperature environment. Creep data for tests with temperature control also exhibited the classic strain profiles. Data indicated that if the load is greater n thermal effects do not manifest. Therefore, creep tests with loads less than 50 percent of the rated load are planned for in the near future

ESTIMATING THE ECONOMIC VALUES ASSOCIATED WITH EPDS FOR ANGUS BULLS AT AUCTION

The genetic traits that an Angus bull possesses convey the reproductive and economic value of the animal to potential buyers. This paper examines and draws comparisons between the value of actual production weights and production EPDs, while also establishing values for ultrasound EPDs. Results indicate that only one EPD, birth weight, was valued by buyers more than its corresponding actual weight, though actual weights and EPDs significantly impacted price. Ultrasound EPDs were also found to be significant, suggesting buyers of Angus bulls consider carcass information when purchasing bulls.Angus Bulls, Birth Weight, Carcass, EPDs, Hedonic Model, Livestock Production/Industries,

Estimating the Economic Value of Specific Characteristics Associated with Angus Bulls Sold at Auction

The genetic traits of a purebred bull convey the reproductive and economic value to buyers. This study examines and compares the value of actual production weights (birth, weaning, and yearling weight), production expected progeny differences (EPDs) (birth, weaning, milk, and yearling), and ultrasound EPDs (carcass quality predictors) for purebred Angus bulls sold at auction. One EPD, birth weight, was valued by buyers more than its corresponding actual weight, though both actual weights and EPDs significantly impact price. Predictors of carcass quality were important in determining price. Finally, several individual animal factors and sale characteristics were significant in determining price.Angus bulls, carcass characteristics, EPDs, marketing factors, production factors, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, Q10, Q12,

Charged-Particle Motion in Electromagnetic Fields Having at Least One Ignorable Spatial Coordinate

We give a rigorous derivation of a theorem showing that charged particles in an arbitrary electromagnetic field with at least one ignorable spatial coordinate remain forever tied to a given magnetic-field line. Such a situation contrasts the significant motions normal to the magnetic field that are expected in most real three-dimensional systems. It is pointed out that, while the significance of the theorem has not been widely appreciated, it has important consequences for a number of problems and is of particular relevance for the acceleration of cosmic rays by shocks.Comment: 7 pages, emulateapj format, including 1 eps figure, to appear in The Astrophysical Journal, Dec. 10 1998 issu

A comparison of dynamic strength index between team-sport athletes

The purpose of this study was to examine the differences in countermovement jump peak force (CMJ-PF), isometric mid-thigh pull peak force (IMTP-PF), and resultant dynamic strength index (DSI) values between team-sport athletes. One hundred and fifteen male and female team-sport athletes performed the CMJ and IMTP to determine peak force (CMJ-PF and IMTP-PF, respectively). Statistically and practically significant differences (p ≤ 0.050; d = 0.49–1.32) in CMJ-PF were evident between teams. Specifically, the greatest CMJ-PFs were produced by the male cricket players and were followed in order by the male basketball, male soccer, female netball, female cricket, and female soccer players. Statistically and practically significant differences (p ≤ 0.045; d = 0.64–1.78) in IMTP-PF existed among sports teams, with the greatest IMTP-PFs were produced by the male soccer players and were followed in order by the male cricket, male basketball, female netball, female soccer, and female cricket players. Statistically and practically significant differences (p ≤ 0.050; d = 0.92–1.44) in DSI were found between teams. These findings demonstrate that CMJ-PF, IMTP-PF, and DSI differ between sports teams and provide normative data for ballistic and isometric PF measures. Strength and conditioning coaches should consider relative changes in CMJ-PF and IMTP-PF when assessing DSI ratios

How a regulatory capital requirement affects banks' productivity: an application to emerging economies

© 2015, Springer Science+Business Media New York. This paper presents a novel approach to measure efficiency and productivity decomposition in the banking systems of emerging economies with a special focus on the role of equity capital. We model the requirement to hold levels of a fixed input, i.e. equity, above the long run equilibrium level or, alternatively, to achieve a target equity-asset ratio. To capture the effect of this under-leveraging, we allow the banking system to operate in an uneconomic region of the technology. Productivity decomposition is developed to include exogenous factors such as policy constraints. We use a panel data set of banks in emerging economies during the financial upheaval period of 2005–2008 to analyse these ideas. Results indicate the importance of the capital constraint in the decomposition of productivity

Hot Gas Structure in the Elliptical Galaxy NGC 4472

We present X-ray spectroscopic and morphological analyses using Chandra ACIS and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo cluster. We discuss previously unobserved X-ray structures within the extended galactic corona. In the inner 2' of the galaxy, we find X-ray holes or cavities with radii of ~2 kpc, corresponding to the position of radio lobes. These holes were produced during a period of nuclear activity that began 1.2 x 10^7 years ago and may be ongoing. We also find an asymmetrical edge in the galaxy X-ray emission 3' (14 kpc) northeast of the core and an ~8' tail (36 kpc) extending southwest of the galaxy. These two features probably result from the interaction of NGC 4472 gas with the Virgo gas, which produces compression in the direction of NGC 4472's infall and an extended tail from ram pressure stripping. Assuming the tail is in pressure equilibrium with the surrounding gas, we compute its angle to our line of sight and estimate that its true extent exceeds 100 kpc. Finally, in addition to emission from the nucleus (first detected by Soldatenkov, Vikhlinin & Pavlinsky), we detect two small extended sources within 10'' of the nucleus of the galaxy, both of which have luminosities of ~7 x 10^38 erg/s.Comment: 25 pages, 11 figures, accepted by Ap

Structural Certification of Human-Rated Inflatable Space Structures

This paper details the results of an initial study to develop a certification plan for human-rated inflatable space structures, including guidelines for qualification testing. Habitable softgoods inflatables are multi-layered shell structures that use high-strength webbing, cordage and broadcloth fabric to carry the skin loads of a variety of volumetric shapes and structural architectures. The primary objectives of this study are to define the key parameters that affect these structures and propose a statistically robust approach to defining safety and knockdown factors based on test and analysis. Current NASA standards for habitable inflatable space structures use a factor of safety of 4, which was inherited from airship design criteria. An updated approach to defining a design factor, taking into account material strength variability, load variability in the article, number of test samples, and damage and degradation effects is specified. Accurate analytical modeling of these structures is hindered by the difficulty of obtaining accurate and consistent material data due to load-history- dependent, nonlinear load versus strain behavior. A building block approach to certification is detailed that uses stochastic modeling and statistical test design and analysis to address the unique challenges these high-strength softgoods structures present. Human-rated inflatable modules are a transformative capability for launching much larger habitable volumes into space than is possible with rigid shell structures. This research aims to provide the framework for certifying these structures for future human space exploration missions

Calibration of a Structural Finite Element Model for a Representative Inflatable Space Structure Utilizing Probabilistic Methods and Surrogate Models

A structural finite element model representing a novel inflatable airlock concept has been calibrated using fullscale test data. The concept, denoted as the NonAxisymmetric Inflatable Pressure Structure (NAIPS), was developed under NASAs Minimalistic Advanced Softgoods Hatch (MASH) Program. The current studies extended previous numerical efforts by incorporating the midbody section of the NAIPS to the dome section and calibrating the model with test data using a process that included surrogate models. Brief overviews of the finite element model and calibration process are provided. The completion of the calibration process provided a model that adequately replicated the test data. The successful demonstration of calibration of a finite element model representing an inflatable habitat provides confidence in the ability to use numerical simulations and associated surrogate models to support design and certification of inflatable space habitats