A Report on the Preliminary design of Composite Cocured LCA Fin

A report on the preliminary design of composite cocured LCA fin is presented. A six spar structural configuration involving laminated carbon composite construction is employed in the design of torsion box. The design studies are carried out using a strength of materials based analysis. Three critical loading cases have been considered in the investigation. Results for various cases studied are presented and discussed

Preparation Studies for Secondary Electron Emission Experiments on Superconducting Niobium

Accelerator driven transmutation of waste is one complementary approach to deal with spent nuclear fuel as compared to permanent storage. High-energy protons generated by a particle accelerator collide with a heavy metal target producing neutrons. Long-lived radioactive isotopes interacting with the neutrons transmute into shorter-lived isotopes. To generate the high-energy protons efficiently, linear accelerators use multi-cell superconducting radio frequency (RF) cavities made of niobium. Superconducting niobium cavities have several advantages, including small power dissipation. The high electromagnetic fields present in these cavities may result in undesired field emission from surface imperfections with the probability of generating an avalanche of secondary electrons from a localized resonant process of impacting known as multipacting. Undesirably, this localized electron current absorbs the RF power supplied to the cavity. This in turn leads to an increase in cavity wall temperature and the eventual breakdown of the wall’s superconductivity. In addition, this can result in structural damage to the cavity surface and the degradation of cavity vacuum. As a result, the Q0 (quality factor) of the cavity is significantly reduced. A good cavity design should be able to eliminate, or at least minimize multipacting. The factors that affect multipacting include shape, surface finish and conditioning, and the secondary electron yield of the material. It is desired to measure the distributed secondary electron yield from a Los Alamos National Laboratory surface prepared niobium test piece in the superconducting state under ultra high vacuum (UHV). A micro-channel plate/delay-line-anode detector (MCP/DLD) capable of single particle position and timing will be used to determine, with the aid of particle tracking codes, the secondary electron yield. The experimental setup primarily evolves around the detector to measure the secondary electron beam and the physics to be studied. Simulation studies using an electromagnetic particle tracking code will be presented to establish the system parameters and geometry, and examine constraints and resolutions of the experimental setup. With the aid of a biasing grid, secondary electrons with 1 eV increments in initial energies between 1 and 20 eV for a wide range of launch angles can be captured and distinguished on a 4.5 cm diameter MCP/DLD detector. An experimental setup is presented

Elevating Repositioning Costs: Strategy Dynamics and Competitive Interactions

Research summary: This article proposes an approach for modeling competitive interactions that incorporates the costs to firms of changing strategy. The costs associated with strategy modifications, which we term “repositioning costs,” are particularly relevant to competitive interactions involving major changes to business strategies. Repositioning costs can critically affect competitive dynamics and, consequently, the implications of strategic interaction for strategic choice. While the literature broadly recognizes the importance of such costs, game-theoretic treatments of major strategic change, with very limited exceptions, have not addressed them meaningfully. We advocate greater recognition of repositioning costs and illustrate with two simple models how repositioning costs may facilitate differentiation and affect the value of a firm\u27s capability to reduce repositioning costs through investments in flexibility. Managerial summary: This article illustrates how the decision to make a strategic change is affected by both the cost to the firm of making the various strategy modifications, as well as the cost to its rivals of changing their strategies in response. These “repositioning costs” are important because they shape the responses each competitor would likely make to a move by the other competitor, and should be anticipated when considering an initial change to one\u27s own strategy. The paper shows how repositioning costs can be used strategically to facilitate differentiation, and to assess the value of potential investments in flexibility

Application of Inelastic Method and Its Comparison with Elastic Method for the Assessment of In-Box LOCA Event on EU DEMO HCPB Breeding Blanket Cap Region

The Helium Cooled Pebble Bed (HCPB) breeding blanket, being developed by the Karlsruhe Institute of Technology (KIT) and its partners is one of the two driver blanket candidates to be selected for the European demonstration fusion power plant (EU DEMO). The in-box Loss of Coolant Accident (LOCA) is a postulated initiating event of the breeding blanket (BB) that must be accounted within the design basis. In this paper, the BB cap region is analyzed for its ability to withstand an in-box LOCA event. Initially, an assessment is performed using conventional elastic design codes for nuclear pressure vessels. However, it is thought that the elastic rules are not ‘equipped’ to assess the material damage modes which are essentially inelastic. Therefore, a non-linear inelastic analysis is further performed to better understand the damage in the material. Two predominant inelastic failure modes are thought to be relevant and addressed: exhaustion of ductility and plastic flow localization. While the design of HCPB BB has been predominantly based on the elastic design-by-analysis studies, results from the present study show that the elastic rules may be overly conservative for the given material and loading and could lead to inefficient designs. To our knowledge, this study is the first attempt to investigate the structural integrity of the European DEMO blankets under in-box LOCA conditions using the inelastic methods

Molecular Identification of Delphinids and Finless Porpoise (Cetacea) from the Arabian Sea and Bay of Bengal

The exact number of extant delphinid species from seas around India is still debated and the lack of adequate field keys and reliable inventory has resulted in misidentification of several species. As a part of a project to develop a molecular taxonomy of cetaceans from this region, partial sequences of mtDNA cytochrome b were generated from accidentally caught/stranded delphinids and finless porpoise. Species were identified by phylogenetic reconstruction of sample sequences with the reference sequences available in portals GenBank (NCBI) and the web-based program DNA Surveillance. A comparison was made with the homologous sequences of corresponding species from other seas of the world. Our molecular investigations allowed us to identify five species of cetaceans from Indian coasts, including Delphinus capensis, previously reported as D. delphis. We detected unique haplotypes in Indo pacific humpbacked dolphin (Sousa chinensis; n = 2) and finless porpoise (Neophocaena phocaenoides; n = 12) from Indian coast. On the other hand, some haplotypes were shared with other regional populations in spinner dolphin (Stenella longirostris; n = 16) and bottlenose dolphin (Tursiops aduncus; n = 3). Common dolphins (Delphinus capensis; n = 2) had both unique and shared haplotypes including one highly divergent sequence

Taking Synchrony Seriously: A Perceptual-Level Model of Infant Synchrony Detection

Synchrony detection between different sensory and/or motor channels appears critically important for young infant learning and cognitive development. For example, empirical studies demonstrate that audio-visual synchrony aids in language acquisition. In this paper we compare these infant studies with a model of synchrony detection based on the Hershey and Movellan (2000) algorithm augmented with methods for quantitative synchrony estimation. Four infant-model comparisons are presented, using audio-visual stimuli of increasing complexity. While infants and the model showed learning or discrimination with each type of stimuli used, the model was most successful with stimuli comprised of one audio and one visual source, and also with two audio sources and a dynamic-face visual motion source. More difficult for the model were stimuli conditions with two motion sources, and more abstract visual dynamics—an oscilloscope instead of a face. Future research should model the developmental pathway of synchrony detection. Normal audio-visual synchrony detection in infants may be experience-dependent (e.g., Bergeson, et al., 2004)