382 research outputs found

    Increased Aluminum Use and Its Impact on the Life-Cycle Energy Cost of Automobiles

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    This paper examines the life-cycle of a passenger automobile including ore refining, manufacture of components, assembly, driving and recycling to provide a general computerized model to be used in evaluating the impact of various material substitution rates and recycling policies on the total system energy consumption. The emphasis is on the use of increased aluminum to replace iron and steel

    Occurrence of Fumonisins B<sub>1</sub> and B<sub>2</sub> in homemade medicinal plants: Exposure assessment in northern Turkey

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    This study was conducted to determine the recent level of contamination with Fumonisin B1 (FB1) and Fumonisin B2 (FB2) in major medicinal plants and to assess consumer exposure in northern Turkey. FB1 and FB2 were investigated by using high performance liquid chromatography (HPLC) with fluorescence detection after derivatization with o-phthaldialdehyde (OPA). A total of 78 homemade medicinal plant samples from 14 species were analysed. The recovery in thyme was 67.2±5.2% for FB1 and 80.8±14.3% for FB2 spiked with 1 μg g–1 of each analyte. The minimum detectable amount for the OPA derivatives of FB1 and FB2 were 1 ng per injection and 2.5 ng per injection, respectively. The limit of quantitation (LOQ) S/N=10 was 0.078 and 0.313 μg g–1, and the limit of detection (LOD) S/N=3 was 0.023 and 0.093 μg g–1 for FB1 and FB2, respectively. FB1 was detected in thyme (0.125) and mint (0.125 and 0.256 μg g–1) samples; however. FB2 toxin was below the detection limit in all samples. These results indicate that toxins might be present in homemade medicinal plants; however, the risk of exposure to fumonisins by the consumption of those plants was lower than the estimated TDI limits (–1 bw)

    A Methodology For Customer Requirements Generation In Communication Systems Planning

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    In electronic communication systems it is nearly impossible to keep up with changing technology. This problem is further aggregated in the developing countries where the contractor (probably a western company) is expected to develop the system from the ground up. A basic problem which confronts this approach is either: 1) The customer will start adding or rejecting some of the capabilities, or 2) The local operation will never use some of the capabilities. Both of these outcomes are costly in terms of time and resources available to a developing country. This paper describes a new methodology for requirements generation to be used by those who want to reduce the adverse consequences of such outcomes, based on structured systems methodology

    Büyük Çökme Problemi Ve Plak-Zemin Etkileşimi İçin Karışık Sonlu Eleman Analizi

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    Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada elastik zemine oturan, büyük çökmeye maruz nispeten kalın plakların karışık sonlu eleman yöntemiyle incelenmesi amaçlanmıştır. Plak şekil değiştirme alanı Mindlin varsayımı ve von Kármán kinematik bağıntılarına dayanmaktadır. Hellinger-Reissner prensibi kullanılarak bir karışık sonlu eleman üretilmiştir. Doğrusal olmayan fonksiyonel artımsal formülasyonla doğrusallaştırılmıştır. Sayısal çözüm için Newton-Raphson ardışık yaklaşım şemasına uyulmuştur. Önerilen karışık sonlu eleman çözüm stratejisi kayma kilitlenmesi problemini otomatik olarak aşmakta ve kuvvet ile momentleri düğüm noktalarında doğrudan hesaplamaktadır. Bir karşılaştırma örneği çözülmüş ve yakınsama davranışı gözlenmiştir. Parametrik çözümler yapılarak plak büyük çökme davranışına elastik zeminin etkisi incelenmiştir.The current study focuses on the mixed finite element solution of moderately thick plates resting on elastic foundation and exhibiting large deflection. Strain field of the isotropic plate was based on the Mindlin plate assumptions and von Kármán kinematic relations. Pasternak elastic foundation model is considered. Hellinger-Reissner principle was used to obtain a mixed finite element solution. Non-linear equations of the problem were linearized using the incremental formulation. Iteration procedure was conducted according to the Newton-Raphson scheme. Proposed mixed solution strategy does not suffer from shear locking problem and gives forces and force couples at the element nodes directly. A comparison study was performed and convergence was observed. The influences of foundation on the large deflection behavior of Mindlin plates were investigated through parametric studies

    The Approach of a Neuron Population Firing Rate to a New Equilibrium: An Exact Theoretical Result

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    The response of a noninteracting population of identical neurons to a step change in steady synaptic input can be analytically calculated exactly from the dynamical equation that describes the population\u27s evolution in time. Here, for model integrate-and-fire neurons that undergo a fixed finite upward shift in voltage in response to each synaptic event, we compare the theoretical prediction with the result of a direct simulation of 90,000 model neurons. The degree of agreement supports the applicability of the population dynamics equation. The theoretical prediction is in the form of a series. Convergence is rapid, so that the full result is well approximated by a few terms

    Hybrid EEG-fNIRS asynchronous brain-computer interface for multiple motor tasks

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    Non-invasive Brain-Computer Interfaces (BCI) have demonstrated great promise for neuroprosthetics and assistive devices. Here we aim to investigate methods to combine Electroencephalography (EEG) and functional Near-Infrared Spectroscopy (fNIRS) in an asynchronous Sensory Motor rhythm (SMR)-based BCI. We attempted to classify 4 different executed movements, namely, Right-Arm—Left-Arm—Right-Hand—Left-Hand tasks. Previous studies demonstrated the benefit of EEG-fNIRS combination. However, since normally fNIRS hemodynamic response shows a long delay, we investigated new features, involving slope indicators, in order to immediately detect changes in the signals. Moreover, Common Spatial Patterns (CSPs) have been applied to both EEG and fNIRS signals. 15 healthy subjects took part in the experiments and since 25 trials per class were available, CSPs have been regularized with information from the entire population of participants and optimized using genetic algorithms. The different features have been compared in terms of performance and the dynamic accuracy over trials shows that the introduced methods diminish the fNIRS delay in the detection of changes

    A Survey of Energy Information Systems and Its Implications for Industrial Energy Management

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    There is a need for state governments to prepare better strategic plans dealing with the use of their energy resources. These plans must be based on reliable information concerning energy resources and usage if they are to make a contribution to sound energy management. This paper presents the results of a survey which was conducted during 1976 and 1977 to determine the availablility of comprehensive energy information systems for planning and controlling the state-wide energy related activities in the United States
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