Shelf Life of Fresh Beef Stored in Master Packages with Carbon Monoxide and High Levels of Carbon Dioxide

Beef steaks from Gluteus medius, Longissimus dorsi, Psoas major and ground beef from Triceps brachii were packed in master packages containing expanded polystyrene trays overwrapped with polyvinyl chloride film under an anoxic atmosphere containing 0.2% CO, 60.0% CO₂ and 39.8% N₂ (T₁) or 0.2% CO/99.8% CO₂ plus oxygen scavengers. After 28 days of storage at 1 and 4°C, the meat quality was evaluated. The visual and instrumental colour of the beef steaks and ground beef were similar to that of fresh meat. Pathogenic bacteria were not detected, and psychrotrophic bacterial counts were lower than 7.5 log CFU/g. Copyright © 2012 John Wiley & Sons, Ltd.     

基于ASP技术设计的体育赛事特色资源包

以网络信息化为平台,建设基于ASP技术设计的体育赛事特色资源包,通过建立体育赛事数据库,在互联网的环境中将与体育赛事有关的文字、图片、视频等信息资源有机的融合在一起。其核心是实现体育赛事资源的整合与共享,促进体育赛事管理朝着科技化、信息化以及专业化的方向发展。     

机械密封静环密封性试验工装设计

机械密封的制造质量是终缩聚釜能否正常运行生产出合格产品的关键.设备的密封由动静环的接触面与0形圈来保证.密封试验原理即设备实际使用过程中的密封原理.从动、静环的制造工艺及结构来看,如果动、静环本身密封性不合格的话,那么问题应该出在镶装处.密封试验时,气体只能从镶四氟块处泄露,这就达到了静环四氟在不受压力情况下测试其密封...     

固体渗硼技术的研究与应用

回顾了渗硼技术的历史,介绍了固体渗硼技术的理论和实践,包括渗硼机制,钢铁渗硼层的组织和性能,冷作模具钢、热作模具钢、不锈钢、耐热钢的固体渗硼,以及固体渗硼技术在某些零件上的应用.     

电动汽车动力蓄电池箱振动特性试验研究

动力蓄电池箱作为电动汽车能量供给的关键设备,其结构设计应在保证存放空间合理布局的基础上,满足多变运行环境和行驶工况下的机械承受、工作安全性、可靠性及使用寿命要求。本文介绍了一种与实际载荷作用等效的动力蓄电池箱振动模拟试验方法,通过改变X轴、Y轴、Z轴3个不同轴向的试验控制参数作一连串可控振动模拟,并在振动激励施加过程中...     

高精度动力电池组电压采集单元的设计

通过完善现有的串联电池组单体电压测量电路,开发了一种动力电池组电压采集单元,解决了电池管理系统中电压采集模块硬件电路复杂,成本高和测量精度低的问题.开发的采集单元采用光电继电器切换巡检的方式,后级精密电阻分压,高精度片外AD转换,转换结果经单片机处理后通过485数据总线发送给电池管理系统主控单元.电池组放电试验结果表明...     

汽车矩阵式动力电池配组的新技术——按伏安特性曲线分选电池的方法

通过研究动力电池伏安特性曲线,根据其一致性来分选电池,该方法用于动力电池矩阵配组。经研究表明,通过此方法分选的电池具有动态特性一致性好,分选简单、快速、方便的优点。     

狭鳕鱼皮胶原多肽组合物水洗面膜的研制

以狭鳕鱼皮胶原多肽、海藻糖和葡萄籽提取物(或藻蓝蛋白)组合物为主要活性成分,以质量分数分别为2.0%,1.0%和4.6%的羧甲基纤维素、海藻酸钠和聚乙二醇1 500为基质主成分,经溶解、搅拌、混合、均质等工艺制备水洗面膜。微生物挑战实验确定以质量分数为1.0%的市售GL-PLUS为面膜防腐剂。体外保湿抗衰老功效研究确定面膜活性成分的添加量(以质量分数计)为胶原多肽3.7%,海藻糖6.5%,葡萄籽提取物(或藻蓝蛋白)0.12%。耐热、耐寒和离心测试结果表明所得面膜具有良好的稳定性。     

The analysis of a two-phase zone with condensation in a porous medium

The one-dimensional steady-state heat and mass transfer in a two-phase zone of a water-saturated porous medium is studied. The system consists of a sand-water-vapour mixture in a tube that is heated from above and cooled from below. Under certain conditions, a two-phase zone of both vapour and water exists in the middle of the tube. A model problem for the temperature and the liquid saturation profiles within this two-phase zone is formulated by allowing for an explicit temperature dependence for the saturation vapour pressure together with an explicit saturation dependence for the capillary pressure. A boundary-layer analysis is performed on this model in the asymptotic limit of a large vapour-pressure gradient. This asymptotic limit is similar to the large-activation-energy limit commonly used in combustion problems. In this limit, and in the outer region away from any boundary layers, it is shown that the temperature profile is slowly varying and that the corresponding saturation profile agrees very well with that obtained in the previous model of Udell [J. Heat Transfer 105 (1983) p. 485] where strict isothermal conditions were assumed. The condensation and evaporation occurring within the boundary layers near the edges of the two-phase zone is examined. Finally, an iterative method is described that allows the temperature profile in the two-phase zone to be coupled to the temperature profiles in the two single-phase zones consisting of either water or vapour. This allows for the computation of the locations of the edges of the two-phase zone within the tube. Numerical computations are performed with realistic values of the parameters.     

电动汽车电池组连接可靠性及不一致性研究

通过对电动汽车用锂离子电池特性的研究,建立了电池组模型并分析了充放电基本规律,重点讨论了电池组可靠性和电池组中单个电池性能不一致性对电池组性能和寿命的影响及对电动汽车行驶性能的影响,提出了在使用方面的解决方案.