Effect of gelatin dip on the oxidative and colour stability of cooked ham and bacon pieces during frozen storage

Summary Samples of cooked ham and bacon were dipped in water or 2, 4 or 6% gelatin solutions. Samples were then packed in oxygen permeable or vacuum packaging film and stored at −18 °C for seven months. Lipid oxidation (TBARS) and colour stability (Hunter a* values) were assessed monthly. The gelatin coating exerted beneficial effects on oxidative and colour stability.     

Testing for reliability improvement or deterioration in repairable systems

This paper reviews the derivation and application of the reverse arrangement test which is used to assess whether a system has improved or deteriorated in a reliability sense. Because the well-known and published table of statistics for this test is erroneous, the prime objective of this paper is to provide the correct statistical table. A secondary aim, however, is to demonstrate how this table can be applied when there is a paucity of failure data for each individual system and to show how a more meaningful reliability assessment can be obtained by pooling results, from the reverse arrangement test, for several systems.     

Improvement of partial discharge (PD) resistance of epoxy resin by using sulfur-containing additives

In the field of high-voltage engineering, it has been desired for a long time to improve the internal PD resistance of epoxy resin without lowering other properties. Recently, the authors discovered that some sulfur compound as curing agents or simple additives improved the PD resistance of rubber markedly, and here an attempt has been made to apply this fact to the case of epoxy resin. As was expected, some sulfur compounds containing SS-bond suppress the deterioration of epoxy resin due to internal partial discharges, and the larger the molecular weight of organic group combining the SS-bond, the longer the effective life of additives. Moreover, to make full use of these additives, it is very important to restrict moisture in the insulation systems. From this study, the authors have proposed the chemical formulation of the suppressive effect of additives for deterioration of epoxy resin due to internal partial discharges.     

Comparison of the contribution of formaldehyde and lipid oxidation products to protein denaturation and texture deterioration during frozen storage of minced ice-fish fillet (Champsocephalus gunnari and Pseudochaenichthys georgianus)

Fillets of the ice-fish Champsocephalus gunnari and Pseudochaenichthys georgianus were minced and mixed with various additives to induce the formation of formaldehyde and oxidation of lipids. The mixtures were frozen and stored for several months and protein denaturation and changes in texture were measured. Samples containing high concentrations of formaldehyde were very tough in texture. However it was found that even severe lipid oxidation (up to 14 mg of malonaldehyde per kg wet mass) had only a slight influence on texture.     

中国城市建设的可持续发展问题分析

在大量调查、分析与研究的基础上，结合中国经济发展中城市快速发展面临的一系列地质灾害，采用自然科学与社会科学相互交叉的方法。分析了城市地质灾害的危险性及对城市发展的影响，根据中国城市发展的实际情况和2001年以后的远景目标，因地制宜地提出了整治城市地质灾害的基本对策与管理措施，为国家在制定城市发展远影规划和奋斗，目标提供基本思路。     

同时计及设备老化与不完全维修的电力系统可靠性评估

在电力系统可靠性评估中,建立精确的元件停运模型至关重要。传统模型忽视了设备老化与维修更新性的影响,导致评估误差随着元件运行时间增长而不断增大。针对这一严重不足之处,提出了计及设备老化与不完全预防性维修的元件时变停运概率模型。该模型采用虚拟年龄与改善因子表征预防性维修对故障率的降低效应,采用威布尔模型表征时间对故障率的增长效应。应用所提出的模型对改进的IEEE RTS-79系统进行了可靠性评估。通过改变部分系统元件的维修成本和预防性维修周期模拟实际维修,给出了新模型中不同维修策略的系统可靠性评估结果,并与传统方法进行了对比分析。结果表明提出的模型能更准确地反映实际维修效果,更精确地预测电力系统中长期可靠性水平。     

废润滑油脱色技术研究及应用进展

根据国内外废润滑油脱色技术的研究和应用情况,分析了废润滑油劣化成色机理,对以吸附法、加氢法、絮凝脱色法为主的废润滑油脱色技术进行了分析总结。从各类废润滑油脱色技术的脱色原理出发,结合具体的废润滑油脱色应用,评述了相关的废润滑油脱色技术的脱色效率、应用进展和存在的问题,并指出了废润滑油脱色技术需要进一步研究的问题和发展的方向。     

工艺物料泄漏对循环冷却水系统的影响及应对措施

某石油化工企业循环冷却水系统出现较为严重的水质恶化现象,通过对装置进出口的循环冷却水水质进行分析,判定水质恶化是因裂解新区丙烯精馏单元冷却器EA-475发生工艺物料泄漏所致。在冷却器无条件停工彻底堵漏的情况下,针对泄漏工艺介质的特性,采取了循环冷却水排污置换,加大缓蚀阻垢剂和杀菌剂的投加量,更换杀菌剂种类,对系统进行粘泥剥离等一系列应对措施。应对措施的实施结果表明,循环冷却水中的异养菌和生物粘泥得到了有效控制,金属腐蚀速率和污垢沉积速率达到了要求,避免了水质恶化对生产装置造成进一步的影响。     

一种航空发动机性能衰退预测的优化算法

针对航空发动机性能衰退预测问题,采用基于过程神经网络的优化算法来对发动机的燃气温度裕度(EGTM)进行预测。为克服过程神经网络学习速度慢的缺点,提出一种基于Tent映射的混沌粒子群优化算法对网络进行训练,建立预测模型。采用某航空公司的EGTM监测数据进行验证,分析结果表明,基于Tent映射的混沌粒子群优化算法具有较高的收敛速度和预测精度,可为航空发动机视情维修决策提供支持。     

Pressure-drop reduction and heat-transfer deterioration of slush nitrogen in horizontal pipe flow

Cryogenic slush fluids such as slush hydrogen and slush nitrogen are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluid alone, there are high expectations for the use of slush fluids in various applications such as clean-energy fuels, spacecraft fuels for improved efficiency in transportation and storage, and as refrigerants for high-temperature superconducting equipment. Experimental tests were performed using slush nitrogen to obtain the flow and heat-transfer characteristics in two different types of horizontal circular pipes with inner diameters of 10 and 15 mm. One of the primary objectives for the study was to investigate the effect of pipe diameter on the pressure-drop reduction and heat-transfer deterioration of slush nitrogen according to changes in the pipe flow velocity, solid fraction and heat flux. In the case of an inner diameter of 15 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 3.6 m/s. On the other hand, in the case of an inner diameter of 10 mm, pressure drop was reduced and heat-transfer characteristics deteriorated when the pipe flow velocity was higher than 2.0 m/s. From these results, it can be seen that a larger pipe diameter produces a higher onset velocity for reducing pressure drop and deteriorating heat-transfer characteristics. Furthermore, based on observations using a high-speed video camera, it was confirmed that pressure drop was reduced and heat-transfer characteristics deteriorated when the solid particles migrated to the center of the pipe and the flow pattern of the solid particles inside the pipe was pseudo-homogeneous.