Residual Stresses and Critical Initial Flaw Size Analyses of Welds

An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). A series of weld analyses are performed to determine the residual stresses in a critical region of the USS. Weld residual stresses both increase constraint and mean stress thereby having an important effect on the fatigue life. The purpose of the weld analyses was to model the weld process using a variety of sequences to determine the 'best' sequence in terms of weld residual stresses and distortions. The many factors examined in this study include weld design (single-V, double-V groove), weld sequence, boundary conditions, and material properties, among others. The results of this weld analysis are included with service loads to perform a fatigue and critical initial flaw size evaluation

Continuous Operation of Radial Multiterminal HVDC Systems Under DC Fault

For a large multi-terminal HVDC system, it is important that a DC fault on a single branch does not cause significant disturbance to the operation of the healthy parts of the DC network. Some DC circuit breakers (DCCBs), e.g. mechanical type, have low cost and power loss, but have been considered unsuitable for DC fault protection and isolation in a multi-terminal HVDC system due to their long opening time. This paper proposes the use of additional DC passive components and novel converter control combined with mechanical DCCBs to ensure that the healthy DC network can continue to operate without disruption during a DC fault on one DC branch. Two circuit structures, using an additional DC reactor, and a reactor and capacitor combination, connected to the DC-link node in a radial HVDC system are proposed to ensure over-current risk at the converters connected to the healthy network is minimized before the isolation of the faulty branch by mechanical DCCBs. Active control of DC fault current by dynamically regulating the DC components of the converter arm voltages is proposed to further reduce the fault arm current. Simulation of a radial three-terminal HVDC system demonstrates the effectiveness of the proposed method

Long-Range Intra-Protein Communication Can Be Transmitted by Correlated Side-Chain Fluctuations Alone

Allosteric regulation is a key component of cellular communication, but the way in which information is passed from one site to another within a folded protein is not often clear. While backbone motions have long been considered essential for long-range information conveyance, side-chain motions have rarely been considered. In this work, we demonstrate their potential utility using Monte Carlo sampling of side-chain torsional angles on a fixed backbone to quantify correlations amongst side-chain inter-rotameric motions. Results indicate that long-range correlations of side-chain fluctuations can arise independently from several different types of interactions: steric repulsions, implicit solvent interactions, or hydrogen bonding and salt-bridge interactions. These robust correlations persist across the entire protein (up to 60 Å in the case of calmodulin) and can propagate long-range changes in side-chain variability in response to single residue perturbations

Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted

The Impact of Demographic Variables on Expenditures for Food Away From Home

Whereas considerable effort has been expended in prior research in discussing the appropriateness of alternative measures of income in expenditure studies, this paper looks in depth at the impact of incorporating a broad range of demographic variables in the expenditure analysis. Food expenditures away from home are used to analyze the additional gains in explanatory power and the impact of demographic variables on income elasticities. Considerable divergence of results is found under the alternative measures of income

Prison Labor: The Local Effects of Ohio Prison Industries

Prison labor has both positive and negative effects. Keeping prisoners active, training and socializing them to be productive citizens after prison, and helping to pay for their incarceration are some of the positives. Potential crowding out of free labor and industry is the major potential negative. This paper addresses the quantitative financial and employment consequences on local free labor and industry of prison industries in Ohio using an input–output model for Ohio. Based on the analysis, prison industries employment in Ohio has negligible to positive employment consequences for the Ohio economy and partially offsets the incarceration cost of the inmates who participate – providing between 5 and 10 percent of the incarceration cost in net cash flow and induced tax revenues. Copyright International Atlantic Economic Society 2006H70,