Analysis of super compact finite difference method and application to simulation of vortex-shock interaction

Turbulence and aeroacoustic noise high-order accurate schemes are required, and preferred, for solving complex flow fields with multi-scale structures. In this paper a super compact finite difference method (SCFDM) is presented, the accuracy is analysed and the method is compared with a sixth-order traditional and compact finite difference approximation. The comparison shows that the sixth-order accurate super compact method has higher resolving efficiency. The sixth-order super compact method, with a three-stage Runge-Kutta method for approximation of the compressible Navier-Stokes equations, is used to solve the complex flow structures induced by vortex-shock interactions. The basic nature of the near-field sound generated by interaction is studied.

Scheme Construction with Numerical Flux Residual Correction (NFRC) and Group Velocity Control (GVC)

For simulating multi-scale complex flow fields like turbulent flows, the high order accurate schemes are preferred. In this paper, a scheme construction with numerical flux residual correction (NFRC) is presented. Any order accurate difference approximation can be obtained with the NFRC. To improve the resolution of the shock, the constructed schemes are modified with group velocity control (GVC) and weighted group velocity control (WGVC). The method of scheme construction is simple, and it is used to solve practical problems.

A pseudo-plastic engagement effect on the toughening of discontinuous fiber-reinforced brittle composites

In brittle composites, such as whisker reinforced ceramics, the sliding of reinforcing fibers against the frictional resistance of matrix is of a pseudo-plastic deformation mechanism. High aspect-ratio whiskers possess larger pseudo-plastic deformation ability but are usually sparse, while, low aspect-ratio ones were distributed widely in the matrix and show low pseudo-plastic deformation ability (engagement effect), also. A comparative investigation was carried out in present study based on a multi-scale network model. The results indicate that the effect of low aspect-ratio whiskers is of most importance. Improving the engagement coefficient by raising the compactness of material seems a more practical way for optimization of discontinuous fiber-reinforced brittle composites in the present technological condition.

Compact difference approximation with consistent boundary condition

For simulating multi-scale complex flow fields it should be noted that all the physical quantities we are interested in must be simulated well. With limitation of the computer resources it is preferred to use high order accurate difference schemes. Because of their high accuracy and small stencil of grid points computational fluid dynamics (CFD) workers pay more attention to compact schemes recently. For simulating the complex flow fields the treatment of boundary conditions at the far field boundary points and near far field boundary points is very important. According to authors' experience and published results some aspects of boundary condition treatment for far field boundary are presented, and the emphasis is on treatment of boundary conditions for the upwind compact schemes. The consistent treatment of boundary conditions at the near boundary points is also discussed. At the end of the paper are given some numerical examples. The computed results with presented method are satisfactory.

Difference schemes on non-uniform mesh and their application

High order accurate schemes are needed to simulate the multi-scale complex flow fields to get fine structures in simulation of the complex flows with large gradient of fluid parameters near the wall, and schemes on non-uniform mesh are desirable for many CFD (computational fluid dynamics) workers. The construction methods of difference approximations and several difference approximations on non-uniform mesh are presented. The accuracy of the methods and the influence of stretch ratio of the neighbor mesh increment on accuracy are discussed. Some comments on these methods are given, and comparison of the accuracy of the results obtained by schemes based on both non-uniform mesh and coordinate transformation is made, and some numerical examples with non-uniform mesh are presented.

Multiscale Method for Turbulent-Flow Computations

A main method of predicting turbulent flows is to solve LES equations, which was called traditional LES method. The traditional LES method solves the motions of large eddies of size larger than filtering scale An while modeling unresolved scales less than Delta_n. Hughes et al argued that many shortcomings of the traditional LES approaches were associated with their inabilities to successfully differentiate between large and small scales. One may guess that a priori scale-separation would be better, because it can predict scale-interaction well compared with posteriori scale-separation. To this end, a multi-scale method was suggested to perform scale-separation computation. The primary contents of the multiscale method are l) A space average is used to differentiate scale. 2) The basic equations include the large scale equations and fluctuation equations. 3) The large-scale equations and fluctuation equations are coupled through turbulent stress terms. We use the multiscale equations of n=2, i.e., the large and small scale (LSS) equations, to simulate 3-D evolutions of a channel flow and a planar mixing layer flow Some interesting results are given.

Microstructure Evolution of Laser Pulse processed Ductile Iron Surface

Pulsed laser beam was used to modify surface processing for ductile iron. The microstructures of processed specimen were observed using optical microscope (OM). Nanoindentation and micro-hardness of microstructures were measured from surface to inner of sample. The experimental results show that, modification zone is consisted of light melted zone, phase transformation hardening area and transient area. The light melt area is made up of coarse dendrite crystalline with a thickness less than 20um, phase transformation hardening area mainly of laminal or acicular martensite, retained austenite and graphite, i.e. M+A prime+ G. The cow-eye microstructure around graphite sphere always is formed in phase transformation hardening area zone, which consisting of a variety structure with the distance from the surface. So, it maybe as a obvious sign distinguishing modification zone border. Finally, the microstructures evolution of laser pulse processed ductile iron was analyzed coupling with beam energy distribution in space and laser pulse heating procession characteristics. The analysis shows that energy distribution of laser pulse has an important effect on microstructure during laser pulse modified ductile iron. Multi-scale and interlace arrangement are the important features for laser pulse modified ductile iron. Of microstructure.

An integrated approach for evaluating coastal vulnerability in a changing climate

Coastal hazards such as flooding and erosion threaten many coastal communities and ecosystems. With documented increases in both storm frequency and intensity and projected acceleration of sea level rise, incorporating the impacts of climate change and variability into coastal vulnerability assessments is becoming a necessary, yet challenging task. We are developing an integrated approach to probabilistically incorporate the impacts of climate change into coastal vulnerability assessments via a multi-scale, multi-hazard methodology. By examining the combined hazards of episodic flooding/inundation and storm induced coastal change with chronic trends under a range of future climate change scenarios, a quantitative framework can be established to promote more sciencebased decision making in the coastal zone. Our focus here is on an initial application of our method in southern Oregon, United States. (PDF contains 5 pages)

Structure Prediction of G-Protein Coupled Receptors

G-protein coupled receptors (GPCRs) form a large family of proteins and are very important drug targets. They are membrane proteins, which makes computational prediction of their structure challenging. Homology modeling is further complicated by low sequence similarly of the GPCR superfamily.

In this dissertation, we analyze the conserved inter-helical contacts of recently solved crystal structures, and we develop a unified sequence-structural alignment of the GPCR superfamily. We use this method to align 817 human GPCRs, 399 of which are nonolfactory. This alignment can be used to generate high quality homology models for the 817 GPCRs.

To refine the provided GPCR homology models we developed the Trihelix sampling method. We use a multi-scale approach to simplify the problem by treating the transmembrane helices as rigid bodies. In contrast to Monte Carlo structure prediction methods, the Trihelix method does a complete local sampling using discretized coordinates for the transmembrane helices. We validate the method on existing structures and apply it to predict the structure of the lactate receptor, HCAR1. For this receptor, we also build extracellular loops by taking into account constraints from three disulfide bonds. Docking of lactate and 3,5-dihydroxybenzoic acid shows likely involvement of three Arg residues on different transmembrane helices in binding a single ligand molecule.

Protein structure prediction relies on accurate force fields. We next present an effort to improve the quality of charge assignment for large atomic models. In particular, we introduce the formalism of the polarizable charge equilibration scheme (PQEQ) and we describe its implementation in the molecular simulation package Lammps. PQEQ allows fast on the fly charge assignment even for reactive force fields.

Caracterização geomorfométrica multiescala de modelos digitais de terreno.

O estudo das formas de relevo através da geomorfometria ciência que quantifica as superfícies topográficas demanda que múltiplas escalas sejam consideradas simultaneamente. Esse fato soma-se à continuidade espacial inerente à topografia, a qual raramente apresenta limites naturais abruptos, para conceder um caráter vago às formas de relevo. Essa dupla vagueza, no entanto, é raramente abordada de forma explícita em trabalhos científicos que, usualmente, valem-se de limiares e definições subjetivas e arbitrárias para descreverem o relevo. Dentro desse contexto, o trabalho apresenta um método inovador de caracterização geomorfométrica multiescala de modelos digitais de terreno (MDTs). A abordagem proposta baseia-se no método de extração de feições morfométricas de Wood (1996), mas o modifica em um número de maneiras: (i) expandindo o número de classes identificadas; (ii) transformando-o em um sistema fuzzy, cujos conjuntos fuzzy são parametrizados automaticamente e; (iii) limitando localmente a escala máxima de análise de maneira não-supervisionada. Como resultado, obtém-se um mapa de feições fundamentais e um mapa de escalas fundamentais que, juntos, sintetizam a estrutura multiescala das superfícies. Além disso, são produzidos mapas de pertinências fuzzy e de índice de confusão para cada escala analisada, assim como versões multiescala dos mesmos. Para avaliar a transferibilidade e o caráter não-supervisionado do método, foram analisados cinco MDTs oriundos de bases de dados distintas, com diferentes resoluções e extensões espaciais, compreendendo regiões continentais, do fundo dos oceanos e do planeta Marte. Os resultados obtidos foram avaliados em relação à utilização de escalas e parametrizações fixas, atestando a capacidade do método de empreender caracterizações geomorfométricas mais completas do que abordagens convencionais. Duas aplicações foram ainda propostas: a parametrização geomorfométrica multiescala e o desenvolvimento de uma assinatura morfométrica multiescala, demonstrando claros caminhos para a continuidade da pesquisa. Como conclusão geral, não obstante a algumas limitações apontadas, considerou-se que o trabalho apresentado alcançou seu objetivo de prover a caracterização geomorfométrica multiescala de modelos digitais de terreno.

Da crítica à relação sociedadenatureza no ensino de Geografia à crítica da questão ambiental na mídia

O ensino de Geografia defrontase com inúmeros desafios no que compete à formação de cidadãos com efetiva atuação social. Neste estudo, apontase, como um destes desafios, o raciocínio espacial, tendo como ponto de partida a compreensão multiescalar e multifacetada da questão ambiental por meio do reconhecimento dos diversos discursos e significados que permeiam essa questão. A mídia constituise, nos últimos tempos, em expressiva instância para a produção de sentidos e de representações acerca do que vem a constituir esse debate, tendo o docente um papel indispensável na mediação da prática educativa e na problematização dos processos que se pretendem hegemônicos. Considerando essas questões, este estudo discute o movimento a ser estabelecido da crítica à relação sociedadenatureza no ensino de Geografia à crítica da questão ambiental apresentada pela mídia. Para tal, desenvolveuse uma metodologia de pesquisa que, envolvendo professores e alunos, buscou confrontar as concepções e práticas enunciadas como as responsáveis pelo debate ambiental em sala de aula com a questão ambiental difundida pela mídia, sendo observados como principais aspectos: a persistente dicotomia sociedade versus natureza como a principal responsável pela dificuldade de professores e alunos na análise da questão ambiental; o não reconhecimento, por parte dos professores, de que essa dicotomia ainda se faz latente no pensar e no fazer geográfico na escola; a carência de uma mediação pedagógica entre o material da mídia e o conhecimento geográfico incorrendo na não problematização de importantes elementos concernentes à questão ambiental; as informações ambientais da mídia têmse sobreposto ao conhecimento geográfico do ambiente a ser pautado na relação sociedadenatureza; o reprodutivismo dos discursos e representações mediáticos sobre a natureza, o ambiente e o espaço pelos alunos. Portanto, a partir dessas constatações, concluise que as percepções da questão ambiental, deslocadas da compreensão analítica e crítica da relação sociedadenatureza na contemporaneidade, podem conduzir a interpretações fragmentárias e simplificadoras do espaço. Como contrapontos a essa perspectiva, são apresentados aspectos das teorias da complexidade (Edgar Morin) e da totalidade (na concepção geográfica de Milton Santos) como importantes alternativas analíticas para o combate da visão dicotômica homem (sociedade) versus meio (natureza) e, por conseguinte, para o fortalecimento da compreensão do espaço enquanto uma totalidade dialética.

Species management in aquatic Habitats overview of sub projects and their management

This is the Species management in aquatic Habitats overview of sub projects and their management produced by the Environment Agency in 1998. This report was under the R&D Project, which it was initiated in 1995 to provide information on species of conservation value of particular relevance to the Environment Agency (then the National Rivers Authority, NRA), in relation to its activities affecting aquatic environments. Outputs comprise Species Action Plans (SAPs), practical management guidelines for Agency staff and third parties, and various research and survey outputs to improve the knowledge base on the status and ecological requirements of priority species. This R&D Technical Report provides an overview of the work undertaken, additionally identifying lessons to be learnt in the management of species-related research within the framework of the UK Biodiversity Action Plan. The process of species selection was initially based upon a wide ranging review of priority species of relevance to the then NRA, encompassing both highly threatened species and species that are relatively common but are at particular risk from Agency activities.

Species management in aquatic habitats WRc RD Interim 1997

This is the Species management in aquatic Habitats WRc Interim 1997 document produced by the Environment Agency in 1997. This document reports progress on R&D Project 640, which aims to provide information on species of conservation value of particular relevance to the Environment Agency, in relation to its activities affecting aquatic environments. A range of stand-alone outputs is being produced, comprising Species Action Plans, practical management guidelines for Agency staff and third parties, and various research outputs to improve the knowledge base on the status and ecological requirements of priority species. The species of conservation values are: water shrew, daubenton’s bat, Kingfisher, yellow wagtail, Grey wagtail, sand martin, reed bunting, dipper, marsh warbler, great crested new, spined loach, brook lamprey, river lamprey, sea lamprey, shining rams-horn snail, little whirlpool rams-horn snail, depressed river mussel, a freshwater pea mussel, native crayfish, and triangular club-rush. The process of species selection was altered during the course of the project by the report on biodiversity by the UK Biodiversity Steering Group (1995). Whilst still including species that were not particularly endangered but were greatly influenced by the activities of the Agency, the project addressed species on the ‘short’ and ‘middle’ priority lists of the Biodiversity report, particularly those for which the Agency had specific responsibilities.