483 research outputs found
A microstructural evaluation of friction stir welded 7075 aluminum rolled plate heat treated to the semi-solid state
Two rolled plates of 7075 aluminum alloy were used as starting material. The plates were welded using a simultaneous double-sided friction stir welding (FSW) process. One way of obtaining feedstock materials for Semi-solid processing or thixoforming is via deformation routes followed by partial melting in the semi-solid state. As both the base plate materials and the friction weld area have undergone extensive deformation specimens were subjected to a post welding heat-treatment in the semi-solid range at a temperature of 628 °C, for 3 min in order to observe the induced microstructural changes. A comparison between the microstructural evolution and mechanical properties of friction stir welded plates was performed before and after the heat-treatment in the Base Metal (BM), the Heat Affected Zone (HAZ), the Thermomechanically Affected Zone (TMAZ) and the Nugget Zone (NZ) using optical microscopy, Scanning Electron microscopy (SEM) and Vickers hardness tests. The results revealed that an extremely fine-grained structure, obtained in the NZ after FSW, resulted in a rise of hardness from the BM to the NZ. Furthermore, post welding heat-treatment in the semi-solid state gave rise to a consistent morphology throughout the material which was similar to microstructures obtained by the thixoforming process. Moreover, a drop of hardness was observed after heat treatment in all regions as compared to that in the welded microstructure
Ergonomics of spatial configurations:a voxel-based modelling framework for accessibility and visibility simulations
How can we assess the ergonomic comfort of a sizeable spatial configuration such as the indoor space of a complex building or an urban landscape when we design, plan, and manage the space? Is there a fundamental difference between indoor [architectural] spatial configurations and outdoor [urban] spatial configurations with respect to ergonomics? Can we have a unified approach to the computational study of spatial ergonomics? This paper addresses these fundamental questions while providing a brief taxonomic review of the scholarly literature on these matters from a mathematical point of view, including a brief introduction to the modelling-based approaches to the computational ways of studying the fundamental effects of spatial configuration on human behaviours. Furthermore, the paper proposes a computational approach for ergonomic assessment of spatial configurations that explicitly allows for combined accessibility and visibility analyses in the built environment. The gist of this approach is the conceptualisation of spatial configurations as rasterised (voxelated) 2D manifold walkable terrains whose voxels have 3D vistas, unifying the simulations and analyses of accessibility and visibility. The paper elaborates on how such a representation of space can provide for conducting various sorts of computational queries, analyses, and simulation experiments for research in spatial ergonomics. The paper concludes with a mapping of the computational modelling approaches pertinent to the study and assessment of spatial ergonomics; and marks avenues of future research on various categories of exploratory, generative, and associative models for ex-ante and ex-post assessment of ergonomic matters at spatial scales.</p
Seroprevalence of varicella zoster virus antibody among young women before marriage in Sanandaj, Iran
Background and Objectives: Varicella Zoster Virus (VZV) infection in pregnant women can cause complications for the mother and fetus. The aim of this study was to assess the immunity against VZV among young women before marriage. Materials and Methods: In this cross-sectional study 250 women attending health centers in Sanandaj, Iran, for pre-marital medical check-up were randomly selected. The VZV IgG measured by ELISA and demographic characteristics of participants including their age, place of residence, number of siblings, occupation, education and history of chickenpox were also recorded. Data were analyzed using R statistical software. Association between VZV infection and participants� characteristics was assessed using Chi-square and Fisher's exact tests. Results: Out of 250 participants, 178 individuals (71.2) diagnosed as antibody positive and 72 (28.8) negative. Our findings revealed that the immunity against VZV increased with individuals� age (P<0.0001) and their number of siblings (P= 0.03). Significant association was found between history of chickenpox and immunity (P <0.001). Positive and negative predictive values of self-reported history of chickenpox obtained by 94.60 and 49.25, respectively. Conclusion: A notable percentage of women were found to be susceptible to VZV, hence they are at risk of getting infected during pregnancy which in turn may result in fetus abnormalities. Screening the immunity and further studies on the need of vaccination before marriage are recommended. © 2016, Tehran University of Medical Science. All rights reserved
Aquaculture land-use policy: the case of clam farming in Thaibinh Province, Vietnam
Policy-making and enforcement remains centralized in Vietnam. Policies have been formulated with less scientific and public justification, thus being largely bureaucratic and infeasible, and in many cases, they have created plagues for people at the grass-roots levels. This article focuses on the implementation of policies related to intertidal land-use and supports for clam farming in the Thaibinh province as a case study to explore the impacts of policies on clam farming and farmers. During the period of 2011-2013, provincial policies on intertidal land allocation and technical and financial supports had boosted clam farming development in the province to a surprising extent. Rapid expansion of the clam farming area has created significant consequences for the farming sector, as well as farmer's lives. However, for the same provincial policies, but with different enforcement, different farming outcomes for clam farmers in the three study communes have resulted. Where farmers had more of a voice and choice in bidding for the intertidal areas they preferred, they faced fewer problems. It is, thus, suggested that a more decentralized policy-making and enforcement are needed, in which more scientific assessment and farmer participation are required to not only make government policy more successful in supporting farmers and achieving their expected outcomes, but also to provide farmers with more room to make their own farming decisions from which farming and marketing risks could be mitigated
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Simulation and life cycle assessment of algae gasification process in dual fluidized bed gasifiers
We present simulation results for the production of algae-derived syngas using dual fluidized bed (DFB) gasifiers.Part of this work was funded by the Technology Strategy
Board (TSB) grant programme, “Carbon Abatement Technologies,
Phase 2 competition for collaborative R&D and feasibility”,
Grant No. TS/J004553. MK acknowledges support by the Singapore National
Research Foundation under its Campus for Research Excellence
And Technological Enterprise (CREATE) program.This is the accepted manuscript. The final version is available at http://pubs.rsc.org/en/Content/ArticleLanding/2015/GC/c4gc01698j#!divAbstract
Prediction of precipitation associated with a western disturbance using a high-resolution regional model: role of parameterisation of physical processes
In this study a non-hydrostatic version of the PSU/NCAR mesoscale model is used to simulate an active western disturbance (WD) that affected the Indian region in January 1997. The role of the planetary boundary layer (PBL) and convection parameterisation schemes in the development of the WD is investigated. Analysis and predictions for some fields, including sea level pressure, geopotential height, temperature, horizontal wind and precipitation are examined. Some statistical scores are also calculated and compared. It is found that the performance of the Hong-Pan (as implemented in the NCAR MRF model) and Betts-Miller (or Grell) schemes as PBL and convection parameterisation schemes respectively are best compared to the other schemes used in this study
Glikozidni sastav polisaharida iz biljke Tinospora cordifolia. II. Glikozidne veze
Polysaccharide from Tinospora cordifolia was isolated, purified, methylated, hydrolyzed, reduced and acetylated. The partially methylated alditol acetate (PMAA) derivative thus obtained was subjected to GC-MS studies. The following types of linkages were noticed: terminal-glucose, 4-xylose, 4-glucose, 4,6-glucose and 2,3,4,6-glucose.Polisaharid iz biljke Tinospora cordifolia je izoliran, pročišćen, metiliran, hidroliziran, reduciran i acetiliran. Tako dobiveni djelomično metilirani alditol acetat (PMAA) analiziran je GC-MS metodom. Određene su sljedeće vrste veza: terminalna glukoza, 4-ksiloza, 4-glukoza, 4,6-glukoza i 2,3,4,6-glukoza
Defects in Crystalline Packings of Twisted Filament Bundles: II. Dislocations and Grain Boundaries
Twisted and rope-like assemblies of filamentous molecules are common and
vital structural elements in cells and tissue of living organisms. We study the
intrinsic frustration occurring in these materials between the two-dimensional
organization of filaments in cross section and out-of-plane interfilament twist
in bundles. Using non-linear continuum elasticity theory of columnar materials,
we study the favorable coupling of twist-induced stresses to the presence of
edge dislocations in the lattice packing of bundles, which leads to a
restructuring of the ground-state order of these materials at intermediate
twist. The stability of dislocations increases as both the degree of twist and
lateral bundle size grow. We show that in ground states of large bundles,
multiple dislocations pile up into linear arrays, radial grain boundaries,
whose number and length grows with bundle twist, giving rise to a rich class of
"polycrystalline" packings.Comment: 10 pages, 7 figure
Nutrition and physical activity in children and adolescents : report 3 : dietary patterns : Department of Human Services (Victoria)
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