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41.
Purdue Improved Crop Storage (PICS) bags were designed to reduce grain storage losses on smallholder farms. The bag consists of three layers: two high-density polyethylene liners fitted inside a woven polypropylene bag. Recently, farmer groups, development relief programs, and government food security agencies have shown interest in PICS bags for large-scale use. PICS bags are conventionally closed by a twist-tie (TT) method, which involves twisting, folding, and tying the lip of each layer individually with a cord. This is not only time and labor intensive, but also may affect the integrity of the liners. We evaluated three new bag closure methods: i) inner liner rolled onto itself and middle liner fold-tied (IR), ii) both liners folded together and tied (FT), and iii) both liners folded and tied separately (FS), along with the conventional twist tie (TT) method. The time to close partially or fully filled 50 kg-capacity PICS bags filled with maize grain was assessed. Results showed that FT was the most time-saving method, reducing bag sealing time by >34% versus the usual TT method. The average internal oxygen levels reached <2% within a week in bags containing grain highly infested with Sitophilus zeamais, while it remained >5% levels for less-infested bags. In both cases, insect population growth was suppressed. Oxygen depletion rates among tying methods remained the same regardless of the closure method used. When large numbers of bags need to be closed, the time-saving FT method is a good alternative PICS sealing method over the conventional twist-tie approach. 相似文献
42.
Yanfeng Li Xiaofeng Wang Kangzhen Xu Bozhou Wang Jirong Song Fengqi Zhao 《Propellants, Explosives, Pyrotechnics》2016,41(5):888-892
Hermetic thermal behavior of 3,4‐diaminofurazan (DAF) was studied by DSC method with special high‐pressure hermetic crucibles. The complete exothermic decomposition process of DAF can be provided. The extrapolated onset temperature, peak temperature, and enthalpy of decomposition at a heating rate of 10 K min−1 are 238.7 °C, 253.0 °C, and −1986 J g−1, respectively. Self‐accelerating decomposition temperature and critical temperature of thermal explosion of DAF are 232.3 and 253.1 °C, respectively. Specific heat capacity of DAF was determined with a micro DSC method and the molar heat capacity is 140.78 J mol−1 K−1 at 298.15 K. Adiabatic time‐to‐explosion of DAF is about 90 s. The thermal stability of DAF is good. 相似文献
43.
Temperatures and levels of refrigerant in the heat exchangers of a gravitational ejector refrigerant make a combined system of numerous mutual couplings. It has some significant properties of self-regulation. There are three kinds of reaction on the self-regulation system of the refrigerator: thermal-type when it is stimulated by changing the temperature of exchangers surrounding, ejector-type stimulated by changing the ejector’s geometry or refrigerant kind, volume-type stimulated by changing the amount of refrigerant. The predicting of a specific reaction of a system balance is difficult but it may be obtained by a mathematical model and calculating experiments. 相似文献
44.
Seeds of mung bean (Vigna radiata (L.) R. Wilczek) are subject to loss of viability due to aging and damage from pulse beetles (or bruchids; Callosobruchus spp.) infestation during storage. We investigated whether seed drying using desiccants and hermetic packaging would prevent or ameliorate these consequences of storage. Sun-dried mung bean seeds at a moisture content of 10% were subjected to further drying for 72 h using five different desiccants: Drying Beads® (a zeolite-based desiccant), silica gel, sodium aluminum silicate, activated alumina, and cow-dung ash (a traditional desiccant). Seeds were subsequently stored in hermetic plastic containers in the presence of these desiccants under ambient conditions along with sun-dried seeds stored in cloth bags or in hermetic containers. In addition, parallel samples of each treatment were inoculated with one pair of bruchid beetles (C. chinensis L.) and stored under the same conditions. The seed drying treatments did not affect initial seed quality (germination percentage and seedling vigor) significantly. After storage for 9 months at ambient temperatures, seeds dried using Drying Beads, silica gel, sodium aluminum silicate and activated alumina had higher germination percentages, seedling vigor indices and soil emergence, and lower electrical conductivity (leakage upon imbibition) and fungal infestation compared to other conditions. In addition, the mung bean seeds inoculated with bruchids and stored with these effective desiccants had less damage, oviposition, and insect respiratory activity in the hermetic containers and maintained higher seed germination and seedling vigor after six months of storage compared to other treatments and controls. The results demonstrate the superior ability of desiccants to quickly and safely dry seeds prior to and during storage and the benefits of such drying and hermetic storage conditions for preventing seed deterioration and insect damage during storage. 相似文献
45.
The khapra beetle, Trogoderma granarium (Everts), is a highly destructive stored product insect that presents a significant threat to stored bagged grain. Hermetic packaging is designed to maintain the quality and safety of stored grain, while continually protecting the grain from insect infestations during storage. The objective of this research was to evaluate a prototype deltamethrin, all-in-one treated hermetic bag on contact efficacy, larval mobility, and the control of T. granarium in artificially infested wheat. The insecticidal activity of the deltamethrin-treated packaging was tested against larvae and adults of T. granarium through contact bioassays. There was a significant reduction in responsive adults after 5 day and >86% of larvae were unresponsive after 9 d of exposure on the treated bag. Trogoderma granarium movement toward a food bait was <10% after a 24 h exposure on the treated bag compared to ~45% of larvae on untreated bag. Lots of 15 kg of wheat were artificially infested with 100 T. granarium larvae and placed inside treated and untreated storage bags, sealed, and stored in a semi-field warehouse, and observed after 2, 6, and 8-weeks for T. granarium survival and grain quality attributes. The weight and number of insect damaged kernels was lower across all storage intervals for grain held in the treated bags, as compared with control bags. Live adult T. granarium were observed at 2-weeks in treated and untreated bags, but there were no live adults observed after 8-weeks of storage in both bags. The new prototype hermetic bags maintained positive grain qualities, however more information on the hermetic parameters are needed to understand how some individuals survived. 相似文献
46.
E. Navarro J.F. Urchueguía J. Gonzlvez J.M. Corbern 《International Journal of Refrigeration》2005,28(6):752
In this experimental investigation five R407C positive displacement hermetic reciprocating compressors, covering different capacities, displacement, stroke-to-bore ratios and number of cylinders, have been characterized using propane as refrigerant by means of a specifically designed characterization test rig. Test results have been systematically compared with their R407C reference performance data to obtain a complete picture on changes on the volumetric efficiency and compressor efficiency amongst others. The compressors used POE oil as lubricant and additional oil circulation rate (OCR) tests at steady state conditions were done to evaluate possible effects and differences to the traditionally used mineral oils. 相似文献
47.
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49.
用低温圆片键合实现传感器和微电子机械系统器件的集成和封装 总被引:1,自引:0,他引:1
PaulLindner HerwigKirchberger MarkusWimplinger Dr.ShariFarrens JoshuaPalensky 《电子工业专用设备》2004,33(3):42-45
集成化是传感器和微电子机械系统(MEMS)的发展方向,即将传感功能、逻辑电路和驱动功能集成在一块单芯片上。未来的系统芯片将能通过集成的传感器和逻辑电路收集并分析外界数据,将这些数据传输到中央处理器并产生必要的动作或反应。讨论了这种系统集成芯片对于封装和集成的要求,并提出一种能够满足这种要求的低温键合技术。同时这种低温键合技术还具有气密性封装、保留透明窗口等优点。 相似文献
50.
B. Raja S. Joseph Sekhar D. Mohan Lal A. Kalanidhi 《International Journal of Refrigeration》2003,26(6):652-658
In a refrigerant compressor, improvement in performance such as reduction of various electrical and mechanical losses, reduction of gas leakage, better lubrication, reduction of suction gas heating etc. can be achieved by maintaining a low temperature rise inside the compressor. Proper selection and location of an internal over load protector relay, estimation of heat transfer coefficient and winding insulation coefficient are also vital in enhancing the performance. In this context it is necessary to understand the temperature distribution inside a compressor for an optimal design. In this paper, a numerical model has been created and a heat transfer analysis for a hermetically sealed reciprocating refrigerant compressor is presented. The temperature distribution inside the compressor has been obtained taking into consideration the various heat sources and sinks and compared with experimental results. The maximum temperature was observed at the rotor which was 427.5 K. The deviation of the predicted rotor temperature from that of experimental value is 5.5% only. A good agreement was found between experimental results and that predicted in the numerical analysis. 相似文献