2,443 research outputs found

    Development of cutter for printed circuit board using hydraulic principle

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    Cutter was known since long times ago as something that was use to cut the thing into smaller piece. Starting from the usual rock at the rock age till the high technology cutter which was make from the precious and valuable material like diamond at this modern age, the cutter was develop to make our daily life more easier and easier. This project is proposed to design and fabricate a cutter as benefit to cut the printed circuit board, the board which contains cuprum as a trace to connect the electricity current to the electronic component like resistors and capacitors. The printed circuit board was widely used in modern electronic and electric component like radio and computer because it can minimize the space and reduce the manufacturing cost by assemble all electronic components together. The usual way to cut the printed circuit board is by using hand because the sensitive of it. By develop the cutter it will make the way to cut the printed circuit board is more efficient without give the damage to the board. In this project, the main purpose of study is to develop the cutter to make sure the cutter can achieve it objective. Developments of cutter are starting by choosing the right cutter's material then design and finally fabricate the cutter

    High-Throughput Computing on High-Performance Platforms: A Case Study

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    The computing systems used by LHC experiments has historically consisted of the federation of hundreds to thousands of distributed resources, ranging from small to mid-size resource. In spite of the impressive scale of the existing distributed computing solutions, the federation of small to mid-size resources will be insufficient to meet projected future demands. This paper is a case study of how the ATLAS experiment has embraced Titan---a DOE leadership facility in conjunction with traditional distributed high- throughput computing to reach sustained production scales of approximately 52M core-hours a years. The three main contributions of this paper are: (i) a critical evaluation of design and operational considerations to support the sustained, scalable and production usage of Titan; (ii) a preliminary characterization of a next generation executor for PanDA to support new workloads and advanced execution modes; and (iii) early lessons for how current and future experimental and observational systems can be integrated with production supercomputers and other platforms in a general and extensible manner

    An experiment on primary education in Angola

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    How should parents be mobilized for education in Africa? We implemented a large-scale field experiment in Angolan primary schools, including three treatments: an information campaign at home, simple parents’ meetings at school, and a combination of both. Our measures of parental mobilization include beneficial practices at home, contacts with teachers, and participation in school institutions. We find that the information increased parents’ involvement at home but had no impact on engagement at school, while the meetings had the opposite effects. After mobilizing parents, only the combined treatment improved management practices and facilities in schools, teachers’ attitudes, and parents’ satisfaction.preprintinpres

    Perspectives on the electrically induced properties of electrospun cellulose/liquid crystal devices

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    A mat of electrospun cellulose fibers are deposed on transparent conductive oxide covered glass, and two such plates enclose a nematic liquid crystal. Thus two new types of Cellulose based Polymer Dispersed Liquid Crystal devices, based on hydroxypropylcellulose and Cellulose Acetate and the nematic liquid crystal E7 have been obtained. The current-voltage characteristics indicates ionic type conduction. Heating-cooling cycles have been applied on the samples and the activation energies have been determined. Simultaneously with the thermo-stimulated currents, the optical transmission dependence on the d.c. electric field and temperature was registered. ON-OFF switching times have been determined for different control voltages. (C) 2011 Elsevier B.V. All rights reserved

    Hierarchical Self-Assembly of Supramolecular Helical Fibres from Amphiphilic C3-Symmetrical Functional Tris(tetrathiafulvalenes)

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    The preparation and self-assembly of the enantiomers of a series of C3-symmetric compounds incorporating three tetrathiafulvalene (TTF) residues is reported. The chiral citronellyl and dihydrocitronellyl alkyl chains lead to helical one dimensional stacks in solution. Molecular mechanics and dynamics simulations combined with experimental and theoretical circular dichroism support the observed helicity in solution. These stacks self-assemble to give fibres that have morphologies that depend on the nature of the chiral alkyl group and the medium in which the compounds aggregate. An inversion of macroscopic helical morphology of the citronellyl compound is observed when compared to analogous 2-methylbutyl chains, which is presumably a result of the stereogenic centre being further away from the core of the molecule. This composition still allows both morphologies to be observed, whereas an achiral compound shows no helicity. The morphology of the fibres also depends on the flexibility at the chain ends of the amphiphilic components, as there is not such an apparently persistent helical morphology for the dihydrocitronellyl derivative as for that prepared from citronellyl chains

    Topological properties of punctual Hilbert schemes of almost-complex fourfolds (I)

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    In this article, we study topological properties of Voisin's punctual Hilbert schemes of an almost-complex fourfold XX. In this setting, we compute their Betti numbers and construct Nakajima operators. We also define tautological bundles associated with any complex bundle on XX, which are shown to be canonical in KK-theory

    The Impact of Including Carbonyl Iron Particles on the Melt Electrowriting Process

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    Melt electrowriting, a high-resolution additive manufacturing technique, is used in this study to process a magnetic polymer-based blend for the first time. Carbonyl iron (CI) particles homogenously distribute into poly(vinylidene fluoride) (PVDF) melts to result in well-defined, highly porous structures or scaffolds comprised of fibers ranging from 30 to 50 mu m in diameter. This study observes that CI particle incorporation is possible up to 30 wt% without nozzle clogging, albeit that the highest concentration results in heterogeneous fiber morphologies. In contrast, the direct writing of homogeneous PVDF fibers with up to 15 wt% CI is possible. The fibers can be readily displaced using magnets at concentrations of 1 wt% and above. Combined with good viability of L929 CC1 cells using Live/Dead imaging on scaffolds for all CI concentrations indicates that these formulations have potential for the usage in stimuli-responsive applications such as 4D printing.Peer reviewe

    Twists and turns in the hierarchical self-assembly pathways of a non-amphiphilic chiral supramolecular material

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    The formation of helical self-assembled fibres by a C-3 symmetric molecule incorporating three tetrathiafulvalene units is shown to be influenced dramatically by the processing conditions, leading to a variety of different chiral forms, including unprecedented croissants

    PLASMA MEMBRANE REDOX SYSTEM IN THE ERYTHROCYTES OF ROWERS: PILOT STUDY

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    Background: The oxidative stress results from a change in the physiological balance between oxidant and antioxidant species. The purpose of this study is twofold: first, to investigate the effects of long-term training in sports with high energy requirements on the redox balance which exists between the plasma vs. the erythrocytes; second, to study the activity of the PMRS (Plasma Membrane Redox System), which is a compensatory mechanism of cellular redox homeostasis, in the rowers’ erythrocytes in order to determine the rowers’ counteraction to oxidative stress. Methods: Venous blood samples was collected from rowers and control group; then FRAP (Ferric Reducing Activity Power) method has been used to determine the antioxidant capabilities both in the plasma and in the erythrocytes of 22 rowers vs. 26 sedentary subjects. For the same groups of subjects, the PMRS in erythrocytes has been also evaluated. Results: The plasmatic antioxidant activity was 21% lower in the group of rowers compared to the sedentary group (p = 0,02). In contrast, no significant differences were found in the reducing activity of the erythrocytes; however the erythrocytes of the rowers have shown values of the PMRS 35% higher than the untrained group (p < 0.0001). Conclusions: Rowing induces a significant oxidative stress in the plasma corresponding to the high intensity training, while this effect lacks in erythrocytes. At the same time an increased quantity of the PMRS has been observed in the erythrocytes. In conclusion, in well trained athletes this not lead to established an oxidative stress condition because long-term training adaptatively improves the efficiency of the antioxidant syste
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