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Atmospheric Air (atmospheric + air)
Selected AbstractsQuality Changes of Highbush Blueberries Fruit Stored in CA with Different CO2 LevelsJOURNAL OF FOOD SCIENCE, Issue 4 2009Carolina Duarte ABSTRACT:, Quality changes of blueberries (Vacccinium corymbosum L. cv Brigitta) were evaluated during CA storage (0 °C) with different concentrations of CO2 (5%, 10%, and 15%) combined with 5% O2, respectively. Atmospheric air (20.9% O2+ 0.03% CO2) was used as control. From samples taken at 0, 24, and 48 d of storage, unmarketable fruits and weight loss were recorded as well as color (h), firmness (g), soluble solid content (%), titratable acidity (% citric acid), ratio, and the monomeric anthocyanin content (ppm). At each sampling time, additional units were kept for 3 d at 10 °C to simulate retail holding conditions. Irrespective of gas concentration, 0.9% of the initial fresh weight was lost after 48 d at 0 °C. CA fruit had better quality than control at the 24 d sampling but due to the high number of unmarketable fruits, this advantage was not observed at 48 d at 0 °C. After 24 d of storage, fruits for CA treatments were more firm and had better color, with higher anthocyanin and acidity levels. Soluble solid content showed no significant differences throughout the cold storage period. Residual effect of CA storage was observed at the retail holding condition yielding better firmness, acidity, and ratio. However, the CO2 level tested increased the number of unmarketable fruit in long-term storage (48 d). Response of "Brigitta" blueberries to the different CO2 levels studied was moderate and could be related to the high storage potential of this cultivar. [source] Modelling the response of sprinklers in compartment firesFIRE AND MATERIALS, Issue 3 2001A. K. Gupta Alpert's expressions are used extensively to calculate the maximum temperature and velocity in the ceiling-jet at any distance, r, from the fire axis. These expressions are valid for unconfined ceilings insofar as the environment outside the ceiling-jet is uniform in temperature and is atmospheric ambient. In compartments the outward flow of hot gases is checked by the presence of bounding walls and so a layer of hot gases is formed in the upper portion of the compartment. The environment outside the ceiling-jet is no longer ambient atmospheric. Expressions due to Alpert becomes unsuitable, unless the effects of the accumulated hot layer are included in these expressions. The effect of the upper layer temperature has been taken by assuming that since the ceiling-jet is completely submerged in the upper hot gas layer, the entrained gases are drawn from this layer only instead of the ambient atmospheric air at T,. Thus T, has been replaced by TL in the Alpert's empirical expression for ceiling-jet temperatures. The proposed equation is then used to calculate the response time of sprinklers fitted in compartments of varying sizes. Calculations have been done for identical conditions to those employed by Evans and compared. Comparison has also been made with Cooper's LAVENT model predictions. The study shows that the present model is capable of predicting the maximum, as well as average, temperatures in the ceiling-jets submerged in the hot gas layer. Copyright © 2001 John Wiley & Sons, Ltd. [source] Prediction of entrance length and mass suction rate for a cylindrical sucking funnelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2010Dipti Prasad Mishra Abstract Conservation equations for mass, momentum and energy have been solved numerically for a cylindrical funnel with louvers (lateral openings on the side wall of the cylindrical funnel through which air can come into it) to compute the suction rate of air into the funnel. The nozzle placed centrally at the bottom of the cylinder ejects high-velocity hot gaseous products so that atmospheric air gets sucked into the funnel. The objective of the work is to compute the ratio of the rate of mass suction to that of the mass ejected by the nozzle for different operating conditions and geometrical size of the funnel. From the computation it has been found that there exists optimum funnel diameter and optimum funnel height for which the mass suction is the highest. The protruding length of the nozzle into the funnel has almost no effect on the mass suction rate after a certain funnel height. The louvers opening area has a very high impact on the mass suction rate. The entrance length for such a sucking funnel is strikingly much lower compared with a simple cylindrical pipe having uniform flow at the inlet at same Reynolds number. A new correlation has been developed to propose the entrance length for a sucking pipe, the rate of mass suction into it and the exhaust plume temperature over a wide range of operating parameters that are normally encountered in a general funnel operations of naval or merchant ship. Copyright © 2009 John Wiley & Sons, Ltd. [source] Direct computation of thermodynamic properties of chemically reacting air with consideration to CFDINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2003Joe IannelliArticle first published online: 2 SEP 200 Abstract This paper details a two-equation procedure to calculate exactly mass and mole fractions, pressure, temperature, specific heats, speed of sound and the thermodynamic and jacobian partial derivatives of pressure and temperature for a five-species chemically reacting equilibrium air. The procedure generates these thermodynamic properties using as independent variables either pressure and temperature or density and internal energy, for CFD applications. An original element in this procedure consists in the exact physically meaningful solution of the mass-fraction and mass-action equations. Air-equivalent molecular masses for oxygen and nitrogen are then developed to account, within a mixture of only oxygen and nitrogen, for the presence of carbon dioxide, argon and the other noble gases within atmospheric air. The mathematical formulation also introduces a versatile system non-dimensionalization that makes the procedure uniformly applicable to flows ranging from shock-tube flows with zero initial velocity to aerothermodynamic flows with supersonic/hypersonic free-stream Mach numbers. Over a temperature range of more than 10000 K and pressure and density ranges corresponding to an increase in altitude in standard atmosphere of 30000 m above sea level, the predicted distributions of mole fractions, constant-volume specific heat, and speed of sound for the model five species agree with independently published results, and all the calculated thermodynamic properties, including their partial derivatives, remain continuous, smooth, and physically meaningful. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effect of oxygen inhibition on composite repair strength over timeJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007Susanna Dall'Oca Abstract The study was aimed at examining whether an oxygen inhibition layer is required for bonding a repairing to a pre-existing composite, and to determine the time required for free radicals within a composite substrate to decay to the extent that the composite repair strength drops significantly. Ten slabs of Gradia Direct Anterior (GC Corp.) were divided into (1) control group: an interfacial oxygen inhibition layer was created by applying and light-curing two layers of bonding resin (D/E Resin, Bisco) to the slabs surface in atmospheric air; (2) experimental group: the absence of an interfacial oxygen inhibition layer was obtained by light-curing the second bonding resin layer in a nitrogen atmosphere. After 1 and 2 h, 1, 14, and 30 days of air storage, a composite repair was layered over the bonding resin. Microtensile bond strengths were measured and statistically analyzed. The curing atmosphere was not a significant factor for bond strength (p = 0.82), and time and curing atmosphere-time interaction were significant (p < 0.001). The 30 day-strengths were the lowest (p < 0.05). An oxygen-inhibited layer is not initially required for bonding to resin composite, and it takes more than 14 days before the bond strength between a pre-existing and a fresh composite drops. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Formation of a Nanocrystalline Layer on the Surface of Stone Wool FibersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2009Yuanzheng Yue In the present paper, we report a simple approach for creating a nanocrystalline layer on the surface of stone wool fibers (SWFs) with a basalt-like composition. The approach is based on a preoxidation process of the SWFs in atmospheric air at a temperature around the glass transition temperature (Tg) for various durations. During preoxidation, the network-modifying ions diffuse from the interior toward the surface of SWFs and react with oxygen on the surface to form oxides. This diffusion process is accompanied by an inward diffusion of electron holes via the oxidation process of Fe2+ to Fe3+. It is found that the diffusion of Mg2+ is dominant in the overall diffusion process. The main phase of the nanocrystalline layer is identified to be periclase (MgO) crystals. The thickness of the nanocrystalline layer can be varied by adjusting the temperature and the duration of preoxidation. The nanocrystalline layer plays a significant role in enhancing the high-temperature stability of the SWFs. [source] Modified atmosphere packaging affects lipid oxidation, myofibrillar fragmentation index and eating quality of beefPACKAGING TECHNOLOGY AND SCIENCE, Issue 2 2009Ina Clausen Abstract The objective of this study was to evaluate the effects of different modified atmosphere packaging (MAP) systems applied during ageing and retail display on the quality of beef longissimus dorsi. The quality of the steaks was measured by sensory analysis, thiobarbituric acid-reactive substances (TBARS), myofibrillar fragmentation index (MFI), protein oxidation, weight loss, cooking loss and vitamin E content. The study included 11 different packaging systems investigated in two separate trials, using O2, CO2, N2 gas and vacuum in combination or alone during ageing and retail display. In some systems, loins were sliced into steaks before packaging, and in other systems, loins were vacuum packed and aged for 14,18 days, and thereafter were sliced and repacked in different atmospheres. Systems including high O2 MAP resulted in a large increase in warmed-over flavour and in TBARS as well as a decrease in juiciness, tenderness and vitamin E content, compared to anaerobic systems. Also, MFI was lower in high O2 MAP steaks, and an increase in protein oxidation was seen, suggesting that the decrease in meat tenderness was due to reduced proteolysis and/or protein oxidation. In addition, the cooked steaks of high O2 MAP looked well done, although the internal temperature was only 62°C, indicating premature browning. Ageing of steaks in N2 did not affect any measured parameter compared to vacuum thermoforming packed muscle. Steaks stored in vacuum skin pack for 20 days were less tender than steaks stored in 100% N2 for 18 days followed by 2 days in atmospheric air. In conclusion, packaging in high O2 concentrations compromises several aspects of meat quality. Copyright © 2008 John Wiley & Sons, Ltd. [source] Changes in the quality of abalone (Haliotis asinina Linnaeus) packaged under atmospheric air, vacuum and modified atmospherePACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2008Romanee Sanguandeekul Abstract Changes in the quality of abalone (Haliotis asinina Linnaeus) meat packaged under modified atmosphere (MA) of 40% CO2/30% O2/30% N2, vacuum and atmospheric air in polyvinylidene chloride (PVDC)/nylon/oriented polypropylene (OPP) pouches, and stored at 2 ± 1°C were investigated. Biochemical indices, such as pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) and sensory evaluation, as well as total plate counts of packaged abalone meat were determined periodically. TMA was not affected by the packaging conditions, and remained low during storage periods. A decrease in pH of the MA packaged abalones during the storage reflected the apparent absorption of CO2. The content of TVB-N slowly increased in the MA packaged abalone, whereas those stored in atmospheric air markedly increased during the storage. The sensory quality of MA packaged abalones was shown to be acceptable up to 15 days, while atmospheric and vacuum-packaged abalones were not acceptable after 3 days of storage. Copyright © 2007 John Wiley & Sons, Ltd. [source] Optimal control of fuel processing system using generalized linear quadratic Gaussian and loop transfer recovery method,,ASIAN JOURNAL OF CONTROL, Issue 5 2010Huan-Liang Tsai Abstract This paper proposes an optimal control system that consists of both feedforward and state-feedback controllers designed using a generalized linear quadratic Gaussian and loop transfer recovery (GLQG/LTR) method for a fuel processing system (FPS). This FPS uses natural gas as fuel and reacts with atmospheric air through a catalytic partial oxidation (CPO) response. The control objective is focused on the regulatory performance of the output vector in response to a desired stack current command in the face of load variation. The proposed method provides another degree of freedom in the optimal control design and gives the compensated system a prescribed degree of stability. Finally, the numerical simulations of compensated FPS reveal that the proposed method displays better performance and robustness properties in both time-domain and frequency-domain responses than those obtained by the traditional LQ Method. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] | |||||||||||||