Two-dimensional finite-element analyses of simulated rotor-fragment impacts against rings and beams compared with experiments

Finite element modeling alternatives as well as the utility and limitations of the two dimensional structural response computer code CIVM-JET 4B for predicting the transient, large deflection, elastic plastic, structural responses of two dimensional beam and/or ring structures which are subjected to rigid fragment impact were investigated. The applicability of the CIVM-JET 4B analysis and code for the prediction of steel containment ring response to impact by complex deformable fragments from a trihub burst of a T58 turbine rotor was studied. Dimensional analysis considerations were used in a parametric examination of data from engine rotor burst containment experiments and data from sphere beam impact experiments. The use of the CIVM-JET 4B computer code for making parametric structural response studies on both fragment-containment structure and fragment-deflector structure was illustrated. Modifications to the analysis/computation procedure were developed to alleviate restrictions

Analysis of simple 2-D and 3-D metal structures subjected to fragment impact

Theoretical methods were developed for predicting the large-deflection elastic-plastic transient structural responses of metal containment or deflector (C/D) structures to cope with rotor burst fragment impact attack. For two-dimensional C/D structures both, finite element and finite difference analysis methods were employed to analyze structural response produced by either prescribed transient loads or fragment impact. For the latter category, two time-wise step-by-step analysis procedures were devised to predict the structural responses resulting from a succession of fragment impacts: the collision force method (CFM) which utilizes an approximate prediction of the force applied to the attacked structure during fragment impact, and the collision imparted velocity method (CIVM) in which the impact-induced velocity increment acquired by a region of the impacted structure near the impact point is computed. The merits and limitations of these approaches are discussed. For the analysis of 3-d responses of C/D structures, only the CIVM approach was investigated

Experimental transient and permanent deformation studies of steel-sphere-impacted or explosively-impulsed aluminum panels

The sheet explosive loading technique (SELT) was employed to obtain elastic-plastic, large deflection 3-d transient and/or permanent strain data on simple well defined structural specimens and materials: initially-flat 6061-T651 aluminum panels with all four sides ideally clamped via integral construction. The SELT loading technique was chosen since it is both convenient and provides "forcing function information" of small uncertainty. These data will be useful for evaluating pertinent 3-d structural response prediction methods

Cap And Trade Allowance Accounting: A Divergence Between Theory And Practice

This study concerns one of the most significant and glaring divergences between theory and practice that has emerged since the accounting discipline’s conceptual framework was developed in the late 1970s.  Through an extensive empirical examination of extant practices with respect to cap and trade allowances allotted to U.S. electric utilities under the Clean Air Act Amendments of 1990, this research demonstrates a surprising—and possibly unsupportable—divergence between expected and actual practice.  The results of this research show that practice and theory diverge in a substantial and negative way.  EPA-issued emissions allowances meet the accepted definition of an economic resource that will provide a future benefit, i.e., an asset.  Yet, examination of five years’ of public financial disclosures for the entities affected by the CAAA shows scant recognition for the acquisition, disposition, or year-end existence of these tradable emissions permits.  Financial statement users and other stakeholders of the affected entities may be seriously misled by the failure to recognize the allowances.  This divergence between theory and practice does not appear to be justifiable

Equity Returns to Small Bank Investors

Unlike most other small firms, there is an excellent record of the initial equity capitalization details of banking organizations when they are formed, as well as subsequent changes, because of the chartering application and reporting requirements of the banking regulatory authorities. By combining these records with the actual approved acquisition price of small banks, the return received by small bank investors from the time of organization through acquisition is determined. For small banks organized after 1972 and acquired from 1980 and through 1988, yearly mean rates of return ranged from 23.07 percent to 10.49 percent. Generally, these returns exceed S&P 500 returns for similar holding periods, but on a Sharpe Performance Index risk adjusted basis were inferior to S&P portfolios in six of nine holding periods and consistently weaker by the same measure to small company investment on the NYSE for this entire period. This inferior risk adjusted performance was unexpected

Disclosure Of EVA Use In Corporate Financial Reports: A Descriptive Analysis

This descriptive study examines a sample of 269 firms that mentioned EVA in their public disclosures.  The key findings of our study are: (1) the use of EVA is found in a cross-section of the industries; (2) the most commonly used source of disclosure is the proxy statement; (3) a majority of the firms use only EVA rather than EVA in combination with other traditional measures; (4) a majority of the sample firms apply EVA at the corporate level alone; (5) three-fourths of the sample firms use EVA as an incentive compensation tool; (6) most firms apply EVA and other metrics only at the executive level for compensation and performance evaluation; and (7) two common modes of compensation using EVA determination are bonus plans and stock options.  The results of our study indicate that firms are steadily adopting EVA as one component of their value management system.  In a related decision context, investors estimate the cost of equity capital to arrive at the intrinsic value of the firm.  Firms can help investors reduce this estimation error by reporting their own estimate of the cost of equity capital, in turn, reducing the valuation error. Our findings have implications for the Securities and Exchange Commission and the Financial Accounting Standards Board in that they should recognize the need to address this issue thereby enhancing the decision usefulness of public reporting

Instructions for the use of the CIVM-Jet 4C finite-strain computer code to calculate the transient structural responses of partial and/or complete arbitrarily-curved rings subjected to fragment impact

The CIVM-JET 4C computer program for the 'finite strain' analysis of 2 d transient structural responses of complete or partial rings and beams subjected to fragment impact stored on tape as a series of individual files. Which subroutines are found in these files are described in detail. All references to the CIVM-JET 4C program are made assuming that the user has a copy of NASA CR-134907 (ASRL TR 154-9) which serves as a user's guide to (1) the CIVM-JET 4B computer code and (2) the CIVM-JET 4C computer code 'with the use of the modified input instructions' attached hereto

Preconditioning-induced ischemic tolerance: a window into endogenous gearing for cerebroprotection

Ischemic tolerance defines transient resistance to lethal ischemia gained by a prior sublethal noxious stimulus (i.e., preconditioning). This adaptive response is thought to be an evolutionarily conserved defense mechanism, observed in a wide variety of species. Preconditioning confers ischemic tolerance if not in all, in most organ systems, including the heart, kidney, liver, and small intestine. Since the first landmark experimental demonstration of ischemic tolerance in the gerbil brain in early 1990's, basic scientific knowledge on the mechanisms of cerebral ischemic tolerance increased substantially. Various noxious stimuli can precondition the brain, presumably through a common mechanism, genomic reprogramming. Ischemic tolerance occurs in two temporally distinct windows. Early tolerance can be achieved within minutes, but wanes also rapidly, within hours. Delayed tolerance develops in hours and lasts for days. The main mechanism involved in early tolerance is adaptation of membrane receptors, whereas gene activation with subsequent de novo protein synthesis dominates delayed tolerance. Ischemic preconditioning is associated with robust cerebroprotection in animals. In humans, transient ischemic attacks may be the clinical correlate of preconditioning leading to ischemic tolerance. Mimicking the mechanisms of this unique endogenous protection process is therefore a potential strategy for stroke prevention. Perhaps new remedies for stroke are very close, right in our cells