3,894 research outputs found

    Phase change material in automated window shades

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    The purpose of this report is to detail the development process for a phase change material window shading system, which stores solar thermal energy and later releases it indoors to provide nighttime space heating. To do this, wax-filled louvers with thermally absorptive front faces were developed and outfitted with a control system, which utilized historical weather data to orient the louvers to specific solar azimuthal angles, thus maximizing the thermal absorption. The system was tested against other common window treatments in a pair of thermally comparable testing structures, and was found to provide energy savings as high as 50%

    Deformed gap space using macro-micro FEA model and transferred into a CFD model

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    Using a cylindrical nozzle and seat of a Pressure Relief Valve (PRV) the surface form and waviness is modelled using actual metrological data i.e. average surface form and waviness (Wa and Wsm) in a 1/4 symmetry manner. To model the surface waviness the technique used is based on the summing technique created by Tsukizoe & Hisakado (1965) for micro contact analysis. Due to the actual surface form measurements being in the micro-meter range, the model is required to incorporate micro and macro-meter dimensions. The material in question is stainless steel. The deformed finite element analysis model is then transferred into a CAD geometry allowing the void space to be meshed and solved using computational fluid dynamics

    Effect of high temperature on structural behaviour of metal-to-metal seal in a pressure relief valve

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    This paper presents a numerical study involving the deformation of contact faces for a metal-to-metal seal in a typical pressure relief valve. The valve geometry is simplified to an axisymmetric problem, which comprises a simple geometry consisting of only three components: A cylindrical nozzle; which is in contact with a disc (representing the valve seat on top); which is preloaded by a compressed linear spring. The nozzle-disk pair is made of the austenitic stainless steel AISI type 316N(L) steel, which is typically used for power plant components. In a previous study, the macro-micro interaction of Fluid Pressure Penetration (FPP) was carried out in an iterative manual procedure at a temperature of 20°C. This procedure is now automated and implemented through an APDL script, which adjusts the spring force according to the current depth of FPP at a macroscale to maintain a consistent seal at elevated temperatures. Based upon the obtained results, specific suggestions to improve the leak tightness of the metal-to-metal seals at elevated temperatures are formulated

    Microflow leakage through the clearance of a metal-metal seal

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    The motivation behind this study is to simulate high pressure gas flow through the clearance between a valve seat and disc when in a closed position using a representative model. This leakage phenomenon is common in metal-to-metal seal pressure relief valves. As a pressure relief valve reaches the set pressure, it is known for the leakage to increase. The representative model that we studied is of an ideal-gas flow through a 2D micro-channel in the slip flow regime. We used a laminar continuum flow solver which solved the mass, momentum and energy equations. In addition, we applied low pressure slip boundary conditions at the wall boundaries which considered Maxwell's model for slip. The channel height was varied from 1μm to 5μm while the length remained at 1.25 mm, this means the length to height ratio varied from 1250 to 250. Inlet pressure was varied from a low pressure (0.05 MPa) to a high pressure (18.6 MPa), while the outlet remained constant at atmospheric. The calculated mass flow rate is compared to an analytical solution giving very good agreement for low pressure ratios and high length to height ratios

    Transport infrastructure and welfare an application to nigeria

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    Transport infrastructure is deemed to be central to development and consumes a large fraction of the development assistance envelope. Yet there is debate about the economic impact of road projects. This paper proposes an approach to assess the differential development impacts of alternative road construction and prioritize various proposals, using Nigeria as a case study. Recognizing that there is no perfect measure of economic well-being, a variety of outcome metrics are used, including crop revenue, livestock revenue, non-agricultural income, the probability of being multi-dimensionally poor, and local gross domestic product for Nigeria. Although the measure of transport is the most accurate possible, it is still endogenous because of the nonrandom placement of road infrastructure. This endogeneity is addressed using a seemingly novel instrumental variable termed the natural path: the time it would take to walk along the most logical route connecting two points without taking into account other, bias-causing economic benefits. Further, the analysis considers the potential endogeneity from nonrandom placement of households and markets through carefully chosen control variables. It finds that reducing transportation costs in Nigeria will increase crop revenue, non-agricultural income, the wealth index, and local gross domestic product. Livestock sales increase as well, although this finding is less robust. The probability of being multi-dimensionally poor will decrease. The results also cast light on income diversification and structural changes that may arise. These findings are robust to relaxing the exclusion restriction. The paper also demonstrates how to prioritize alternative road programs by comparing the expected development impacts of alternative New Partnership for Africas Development projects. Document type: Boo

    Phytoremediation of Nutrients and Organic Carbon from Sago Mill Effluent using Water Hyacinth (Eichhornia crassipes)

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    The aim of this study was to investigate the ability of floating water hyacinth (Eichhornia crassipes) to survive under selected concentrations of sago mill effluent (SME) and determine the nutrient uptake by the plant. Phytoremediation at 10, 15, and 20% (VSME/Vwater) SME concentrations by water hyacinth was conducted under greenhouse conditions for 30 d in a batch type experiment. After 30 d of phytoremediation, the removal efficiency of chemical oxygen demand, ammonia and phosphorus from SME wastewater were (86.4% to 97.2%), (91.4% to 97.3%) and (80.4 to 97.2%), respectively. The results proved the efficiency of water hyacinth to polish SME wastewater

    Development of Liquid Chromatography-Mass Spectrometry (LC-MS) Method for Quantification of Broccoli Sulforaphane

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    This is the final version. Available from Springer via the DOI in this record. The data that support the findings of this study are available from the corresponding author upon reasonable request.Sulforaphane (SFN) is an isothiocyanate and the product of the hydrolysis of glucoraphanin (GRA) by myrosinase. Broccoli is one of the rich sources of GRA and thus SFN. SFN possess a wide range of bioactivities and is considered an anti-cancer phytochemical. Most of the current common methods used to quantify SFN are based on high-pressure liquid chromatography (HPLC) with diode array detection (DAD) — also known as HPLC-DAD. Although this technique has shown encouraging results, the detection of SFN by DAD is relatively weak and affected by high interference of sample matrices. Therefore, the aim of this study was to develop a liquid chromatography-mass spectrometry (LC-MS) method in which SFN is identified by molecular mass to give more accurate results. The developed method demonstrated a highly reproducible retention time (7.204 ± 0.008 min), producing a sharp, symmetrical and well-defined sulforaphane peak in standard and test samples. The most dominant ion of sulforaphane in the pure and test samples was 178 m/z ([M + H]^+). In terms of linearity, the calibration curve had a coefficient of determination (R^2) of 0.9963. The limit of detection of this method is 1.3 ng/mL, and the limit of quantification is 3.9 ng/mL, indicating high sensitivity. The uniformity of peak shape and retention time in both pure and test samples were the same suggesting excellent selectivity. Overall, the developed method showed promising results in identifying and quantifying broccoli SFN.QUEX InstitutePepsiCo, In

    Determination of glucosinolates and isothiocyanates in glucosinolate-rich vegetables and oilseeds using infrared spectroscopy: A systematic review.

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    This is the final version. Available from Taylor & Francis via the DOI in this recordCruciferous vegetables and oilseeds are rich in glucosinolates that can transform into isothiocyanates upon enzymic hydrolysis during post-harvest handling, food preparation and/or digestion. Vegetables contain glucosinolates that have beneficial bioactivities, while glucosinolates in oilseeds might have anti-nutritional properties. It is therefore important to monitor and assess glucosinolates and isothiocyanates content through the food value chain as well as for optimized crop production. Vibrational spectroscopy methods, such as infrared (IR) spectroscopy, are used as a nondestructive, rapid and low-cost alternative to the current and common costly, destructive, and time-consuming techniques. This systematic review discusses and evaluates the recent literature available on the use of IR spectroscopy to determine glucosinolates and isothiocyanates in vegetables and oilseeds. NIR spectroscopy was used to predict glucosinolates in broccoli, kale, rocket, cabbage, Brussels sprouts, brown mustard, rapeseed, pennycress, and a combination of Brassicaceae family seeds. Only one study reported the use of NIR spectroscopy to predict broccoli isothiocyanates. The major limitations of these studies were the absence of the critical evaluation of errors associated with the reference method used to develop the calibration models and the lack of interpretation of loadings or regression coefficients used to predict glucosinolates.QUEX Institut

    Quarkonium Interactions in Hadronic Matter

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    The cross section for the \J~and \U~interaction with light hadrons is calculated in short-distance QCD, based on the large heavy quark mass and the resulting large energy gap to open charm or beauty. The low energy form of the cross section is determined by the gluon structure functions at large x x; hence it remains very small until quite high energies. This behaviour is experimentally confirmed by charm photoproduction data. It is shown to exclude \J~absorption in confined hadronic matter of the size or density attainable in nuclear collisions; in contrast, the harder gluon spectrum in deconfined matter allows break-up interactions.Comment: 10 pages + 4 Figures, plain TeX, CERN-TH.7274/94, BI-TP 94/24 (Minor modifications were made and misprints were removed in this revised version; the figures are available upon request from the authors
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