Interface concerns of ejector integration in V/STOL aircraft

A number of areas which have in the past contributed to weight, complexity, and thrust losses in the ejector-powered V/STOL vehicle were identified. Most of these interfaces taken singly do not represent a severe compromise to the vehicle; however, the bottom line is that the sum of compromises and the subsequent effects on performance, flight operations and maintenance have rendered the ejector V/STOL aircraft unattractive. In addition to some of the unique ejector/aircraft integration problems, the vehicle by virtue of having a V/STOL capability, is compromised in other areas. To be successful and acceptable, the advantages must outweight the disadvantages and simplicity with minimum penalties must be the rule. It is concluded that more emphasis must be placed on the ejector/aircraft interface for the concept to be successful

Development of a 1000V, 200A, low-loss, fast-switching, gate-assisted turn-off thyristor

Feasibility was demonstrated for a thyristor that blocks 1000V forward and reverse, conducts 200A, and turns on in little more than 2 microsec with only 2A of gate drive. Its features include a turn-off time of 3 microsec achieved with 2A of gate assist current of a few microseconds duration and an energy dissipation of only 12 mJ per pulse for a 20 microsec half sine wave, 200A pulse. Extensive theoretical and experimental study of the electrical behavior of thyristors having a fast turn-off time have significantly improved the understanding of the physics of turning thyristor off. Thyristors of two new designs were fabricated and evaluated. The high speed and low power were achieved by a combination of gate amplification, cathode shunting, and gate-assisted turn-off. Two techniques for making this combination practical are described

Identification of the YfgF MASE1 domain as a modulator of bacterial responses to aspartate

Complex 3'-5'-cyclic diguanylic acid (c-di-GMP) responsive regulatory networks that are modulated by the action of multiple diguanylate cyclases (DGC; GGDEF domain proteins) and phosphodiesterases (PDE; EAL domain proteins) have evolved in many bacteria. YfgF proteins possess a membrane-anchoring domain (MASE1), a catalytically inactive GGDEF domain and a catalytically active EAL domain. Here, sustained expression of the Salmonella enterica spp. Enterica ser. Enteritidis YfgF protein is shown to mediate inhibition of the formation of the aspartate chemotactic ring on motility agar under aerobic conditions. This phenomenon was c-di-GMP-independent because it occurred in a Salmonella strain that lacked the ability to synthesize c-di-GMP and also when PDE activity was abolished by site-directed mutagenesis of the EAL domain. YfgF-mediated inhibition of aspartate chemotactic ring formation was impaired in the altered redox environment generated by exogenous p-benzoquinone. This ability of YfgF to inhibit the response to aspartate required a motif, (213)Lys-Lys-Glu(215), in the predicted cytoplasmic loop between trans-membrane regions 5 and 6 of the MASE1 domain. Thus, for the first time the function of a MASE1 domain as a redox-responsive regulator of bacterial responses to aspartate has been shown

Determination of Newton's gravitational constant, G, with improved precision Status report, 1 Apr. - 30 Sep. 1965

Apparatus and techniques for laboratory determination of Newtonian gravitation constan

Development of a 1000V, 200A, low-loss, fast-switching, gate-assisted turn-off thyristor

The results of a program to develop a fast high power thyristor that can operate in switching circuits at frequencies of 10 to 20 kHz with very low power loss are given. Feasibility was demonstrated for a thyristor that blocks 1000V forward and reverse, conducts 200A, turns on in little more than 2 more microseconds with only 2A of gate drive, turns off in 3 microseconds with 2A of gate assist current and has an energy dissipation of only 12 mJ per pulse for a 20 microsecond half sine wave 200A pulse. Data were generated that clearly showed the tradeoffs that can be made between the turn off time and forward drop. The understanding of this relationship is necessary in the selection of deliverable thyristors with turn off times up to 7 microseconds to give improved efficiency in a series resonant dc to dc inverter application

STATISTICAL DESIGN AND ANALYSIS OF DAIRY NUTRITION EXPERIMENTS TO IMPROVE DETECTION OF MILK RESPONSE DIFFERENCES

The objective of many dairy nutrition experiments is to determine the effect of certain dietary treatments on milk production and quality responses. However, milk responses are quite variable and cows (experimental units) are expensive and have substantial maintenance costs. This manuscript reviews principles for planning to obtain good data relevant to the hypothesis, experimental design to control inherent variation, and interpreted analyses to facilitate understanding of dairy relationships. Emphasis is placed on assurance that milk response differences due to dietary treatments will have a high probability of being detected as significant. Guidelines addressing these principles along with suggested computer programs are presented. Results of two dairy nutrition experiments are included to illustrate use of the presented guidelines to maximize detection of real differences in milk response due to dietary treatments

Evaluation of Body Fat Prediction Equations from a Portable A-Mode Ultrasound (BodyMetrix) Compared to Bod Pod

A-mode ultrasound is a relatively inexpensive and noninvasive way of measuring subcutaneous fat thickness and estimating body fat percentage (%BF). The BodyMetrix BX2000 A-mode ultrasound is programmed with nine different equations that can be used to estimate %BF. The purpose of this study was to compare the %BF estimation from all nine equations available for adult males in this ultrasound system to the %BF estimation from Bod Pod air displacement plethysmography. Ultrasound measures were taken at 10 body sites on 42 males of varying age (28.6 ± 11.9 y), height (182.4 ± 7.6 cm), weight (84.5 ± 16.9 kg), and body mass index (24.5 ± 4.6 kg/m2). The %BF from the nine ultrasound formulas were compared to the estimate from the Bod Pod with a repeated-measures ANOVA. Three of the nine equations -- the Jackson and Pollock 3 site (JP3), Jackson and Pollock 7 site (JP7), and the NHCA 4 site -- had acceptable correlation coefficients (\u3e 0.80), low mean differences that were not significant (p \u3e 0.05), and insignificant bias. None of the equations had errors \u3c 3.5%BF, but all three of these formulas had standard error of estimate (SEE) and total error (TE) of about 4%BF. Based on these findings, the JP3, JP7, and NHCA 4-site formulas in the BX2000 A-mode ultrasound are recommended over the other formula options for estimating the %BF of men

Working Notes from the 1992 AAAI Workshop on Automating Software Design. Theme: Domain Specific Software Design

The goal of this workshop is to identify different architectural approaches to building domain-specific software design systems and to explore issues unique to domain-specific (vs. general-purpose) software design. Some general issues that cut across the particular software design domain include: (1) knowledge representation, acquisition, and maintenance; (2) specialized software design techniques; and (3) user interaction and user interface