Application of minimum plutonium criteria at EOC to optimize the fuel loading pattern in VVER-1000 reactors

Most of the strategies yet implemented to optimal fuel loading pattern design in nuclear power reactors, are based on maximizing the core effective multiplication factor (K_eff) to extract maximum energy and lowering the local power peaking factor (P_q) from a predetermined value. However, a new optimization criterion could be of interest, aiming at maximum burn-up of the plutonium content in fuel assemblies, i.e., minimization of remaining plutonium in spent fuel at the end of cycle (EOC). In this research, we developed a new strategy for optimal fuel core loading pattern of a VVER-1000 reactor, based on multi-objective optimization: lowering the P_q, maximization of the K_eff and minimization of remaining plutonium (Pu) in fuels at EOC. This strategy has been implemented considering exact calculations of fuel burn-up during the equilibrium cycle using WIMSD and CITATION calculation codes. We used the genetic algorithm to find the optimum fuel loading pattern. Simulation results show that this strategy can reduce the remaining Pu of the fuels at EOC while considering limitations on core power peaking and multiplication factor.     

CHM: an annotation- and component-based hypervideo model for the Web

Hypervideos are hypermedia documents that focus on video content. While they have long been deployed using specialized software or even hardware, the Web now offers a ground for them to fit into standardized languages and implementations. However, hypervideo design also currently uses very specific models limited to a single class of documents, or very generic hypermedia models that may not appropriately express their specific features. In this article we describe such features, and we introduce CHM, an annotation-driven and component-based model to conceptualize hypervideos through a high level operational specification. An extensible set of high level components is defined to emphasize the presentation and interaction features modeling, while lower level components offer more flexibility and customization opportunities. Being annotation-based, the model promotes a clear separation between video content/metadata and their various potential presentations. We also describe WebCHM, an implementation of CHM with standard Web technologies that provides a general framework to experiment with hypervideos on the Web. Two examples are provided as well as a preliminary usage study of the model and its implementation to validate our claims and proposals.     

A meshless method for solving mKdV equation

A meshless method based on a global collocation with radial basis functions for the numerical solution of the modified Korteweg–de Vries (mKdV) equation is presented. Standard types of radial basis functions are applied in the method of collocation. The stability analysis of the method is dealt with using a linearized stability analysis. The method?s accuracy and efficiency are examined by the simulation of a single soliton and interaction of two solitary waves. The four invariants of the motion are evaluated to determine the conservation properties of the method. A comparison with some earlier reported results is also carried out.     

Virtual and augmented reality for cultural computing and heritage: a case study of virtual exploration of underwater archaeological sites (preprint)

The paper presents different issues dealing with both the preservation of cultural heritage using virtual reality (VR) and augmented reality (AR) technologies in a cultural context. While the VR/AR technologies are mentioned, the attention is paid to the 3D visualization, and 3D interaction modalities illustrated through three different demonstrators: the VR demonstrators (immersive and semi-immersive) and the AR demonstrator including tangible user interfaces. To show the benefits of the VR and AR technologies for studying and preserving cultural heritage, we investigated the visualisation and interaction with reconstructed underwater archaeological sites. The base idea behind using VR and AR techniques is to offer archaeologists and general public new insights on the reconstructed archaeological sites allowing archaeologists to study directly from within the virtual site and allowing the general public to immersively explore a realistic reconstruction of the sites. Both activities are based on the same VR engine, but drastically differ in the way they present information and exploit interaction modalities. The visualisation and interaction techniques developed through these demonstrators are the results of the ongoing dialogue between the archaeological requirements and the technological solutions developed.     

Slip flow forced convection in a microchannel with semi-circular cross-section

This paper offers theoretical results for fully developed slip-flow forced convection through a microchannel of semicircular cross-section. Numerical results are also presented to study the developing region. Velocity slip and temperature jump boundary conditions are applied at the uniformly heated walls. The results from the two different sources are cross validated and those pertaining to the limiting case of no-slip flow are found to be in good agreement with those available in the literature.     

Time and power scheduling in an ad hoc network with bidirectional relaying and network coding

Network coding (NC) is a technique that allows intermediate nodes to combine the received packets from multiple links and forwarded to subsequent nodes. Compared with pure relaying, using NC in a wireless network, one can potentially improve the network throughput, but it increases the complexity of resource allocations as the quality of one transmission is often affected by the transmission conditions of multiple links. In this paper, we consider an ad hoc network, where all the links have bidirectional communications, and a relay node forwards traffic between the source and the destination nodes using NC. All transmissions share the same frequency channel, and simultaneous transmissions cause interference to each other. We consider both digital NC and analog NC strategies, referred to as DNC and ANC, respectively, and schedule transmission time and power of the nodes in order to maximize the overall network throughput. For DNC, an optimum scheduling is formulated and solved by assuming that a central controller is available to collect all the link gain information and make the scheduling decisions. Distributed scheduling schemes are proposed for networks using DNC and ANC. Our results indicate that the proposed scheduling scheme for DNC achieves higher throughput than pure relaying, and the scheduling scheme for ANC can achieve higher throughput than both DNC and pure relaying under certain conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Uncooled InAs-GaSb type-II infrared detectors grown on GaAssubstrates for the 8-12-μm atmospheric window

We report on the growth and characterization of type-II infrared detectors with an InAs-GaSb superlattice active layer for the 8-12-μm atmospheric window at 300 K. The material was grown by molecular beam epitaxy on semi-insulating GaAs substrates. Photoconductive detectors fabricated from the superlattices showed 80% cutoff at about 12 μm at room temperature. The responsivity of the device is about 2 mA/W with a 1-V bias (E=5 V/cm) and the maximum measured detectivity of the device is 1.3×10⁸ cm.Hz^1/2/W at 11 μm at room temperature. The detector shows very weak temperature sensitivity. Also, the extracted effective carrier lifetime, τ=26 ns, is an order of magnitude longer than the carrier lifetime in HgCdTe with similar bandgap and carrier concentration     

Atomic ordering and magnetism in L10 ordered FePd alloys

Intermetallic compounds due to their promising corrosion resistance and high-temperature mechanical strength give hope for their application as high-temperature structural materials. Inter-metallics of L1₀ type structure in recent years in addition have attracted great interest as potential recording media. These alloys are ferromagnetic and display marked mechanical and magnetic anisotropy with the tetragonal c-axis of the ordered domains as the “easy axis” of magnetization High-density magnetic recording may be achieved by a preferential domain orientation with the c-axis perpendicular to the surface, if these materials can be stabilized as low-dimensional magnetic structures. Knowledge of kinetic parameters, that determine alloy stability is essential for alloy design. technical application, and performance of materials. We used FePd as a model system for this class of L1₀-ordered intermetallics and have studied the changes of long-range order during heat treatments in the bulk and in thin films produced by different techniques. Results of X-ray diffraction (XRD). resistivity measurement. Mößbauer spectroscopy, and measurement of magnetization in both geometries are compared.     

SAFL Baffle retrofit for suspended sediment removal in storm sewer sumps

Standard sumps (manholes) provide a location for pipe junctions and maintenance access in stormwater drainage systems. Standard sumps can also remove sand and silt particles from stormwater, but have a high propensity for washout of the collected sediment. With appropriate maintenance these sumps may qualify as a stormwater best management practice (BMP) device for the removal of suspended sediment from stormwater runoff. To decrease the maintenance frequency and prevent standard sumps from becoming a source of suspended sediment under high flow conditions, a porous baffle, named the SAFL Baffle, has been designed and tested as a retrofit to the sump. Multiple configurations with varying percent open area and different angles of attack were evaluated in scale models. An optimum configuration was then constructed at the prototype scale and evaluated for both removal efficiency and washout. Results obtained with the retrofit indicate that with the right baffle dimensions and porosity, sediment washout from the sump at high flow rates can be almost eliminated, and removal efficiency can be significantly increased at low flow rates. Removal efficiency and washout functions have been developed for standard sumps retrofitted with the SAFL Baffle. The results of this research provide a new, versatile stormwater treatment device and implemented new washout and removal efficiency testing procedures that will improve research and development of stormwater treatment devices.