基于耐热量降低原理的配电系统微机反时限过流保护

提出航空及民用配电系统耐热量降低原理,对国际电工委员会(IEC)标准规定的反时限特性曲线,研究用电设备过流保护跳闸条件、过流损坏的相对临界耐热量和电流热功率,设计一种快速高精度的反时限过流保护方法,并仿真分析其实现过程。统一定义10倍过流延时时间为时间整定值,使反时限函数具有统一明确的量化参数,并推导出相应的反时限特性方程,使参数更容易整定。该方法克服了传统反时限过流保护不能准确反映电流快速变化时真实故障状态的缺点。根据耐热量降低原理推导一种简单实用的反时限动态特性测试方法,静态和动态实验结果表明该方法快速性好和准确性高,为航空供电系统机载用电设备及民用设备反时限保护提供了实现方案。

Heat Resisting Mechanism of Heat-Resisting Aluminum Alloy Conductor and Its Application in Transmission Line

In this paper the heat withstanding mechanism of heat-resisting aluminum alloy conductor is discussed, the types and performance of the conductor and its application on transmission lines are analyzed and introduced, and suggestions on accelerating exploitation and application of the conductor are put forward.

Measurement of Thermal Resistance of Heat-resistant Fabrics with a Guarded-hot-box

A novel analytical method with the guarded-hot-box （GHB） in investigating the thermal resistance of heat-resistant fabrics is described and the analytical method is also presented in this paper. The new apparatus is capable of measure thermal resistance of the fabrics in high temperature up to an average applied temperature of 250~C. The maximum measurement error of the apparatus is 6.5% and relative error is less than 2.8% between the introduced method and standard given value. In the G/-IB method, air layer thickness is the most important factor that influences measurement value of thermal resistance of heat-resistant fabrics. Results show that the method is more accurate and efficient than GBl1048-89 one in measuring thermal resistance of heat-resistant fabrics.

Semisolid lead-antimony alloys for cars batteries

The application of semisolid process was investigated on Pb-Sb alloys that are normally used for metallic parts in car batteries, in order to increase their mechanical properties and corrosion resistance.The semisolid behaviour of a Pb-4%Sb alloy was analysed by means of rheological and calorimetry differential scanning experiments.The alloy was melted, treated by ultrasound to obtain the semisolid state and then poured into permanent moulds.Some of these samples were also heated in semisolid temperature range and injected in thixo-casting apparatus.Both poured and injected samples were characterized by metallographic analysis, mechanical test and electrochemical corrosion experiments.The results show an improvement of mechanical and corrosion resistance with respect to samples obtained by conventional casting technique.

Research and Development of Heat-Resistant Materials for Advanced USC Power Plants with Steam Temperatures of 700℃ and Above

Materials-development projects for advanced ultra-supercritical(A-USC) power plants with steam temperatures of 700℃ and above have been performed in order to achieve high efficiency and low CO_2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%–12% Cr steels with nickel(Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700℃ and above. To minimize the requirement for expensive Ni-base alloys, martensitic 9%–12% Cr steels can be applied to the next highest temperature components of an A-USC power plant, up to a maximum of 650℃. This paper comprehensively describes the research and development of Ni-base alloys and martensitic 9%–12% Cr steels for thick section boiler and turbine components of A-USC power plants, mainly focusing on the long-term creep-rupture strength of base metal and welded joints, strength loss in welded joints, creep-fatigue properties, and microstructure evolution during exposure at elevated temperatures.

Protective effects of Modified Linggui Zhugan Decoction combined with short-term very low calorie diets on cardiovascular risk factors in obese patients with impaired glucose tolerance

OBJECTIVE:To observe the protective effects of modified Linggui Zhugan Decoction combined with short-term very low calorie diets(VLCDs) on cardiovascular risk factors in obese patients with impaired glucose tolerance(IGT).METHODS:Eighty-five obese patients with IGT of spleen hypofunction and dampness accumulation type were randomly divided into treated group(n=45)and control group(n=40).The treated group was given Linggui Zhugan Decoction combined short-term VLCDs.The control group was given basic weight-reduction treatment.The total course was 6 months.Changes of fasting plasma glucose(FPG),2-hour postprandial blood glucose(2hPG),glycosylated hemoglobin(HbA1c),fasting insulin(FINS),lipid metabolism,blood pressure,body mass index(BMI) and waist circumference(WC) were observed,and the outcomes were reviewed after the treatment.RESULTS:Compared with the control group,the levels of FPG,2hPG,HbA1c,FINS,HOMA-IR decreased significantly(P<0.05),and the indexes of total cholesterol(TC),triglyceride(TG),low-density lipoprotein(LDL),systolic blood pressure(SBP),diastolic blood pressure(DBP),BMI and WC were improved significantly(P<0.05) in the treated group.The transformation rate of normal glucose tolerance(NGT) was higher in treatment group than control group(P<0.01).No severe adverse reaction was found in the therapeutic course.CONCLUSION:The modified Linggui Zhugan Decoction combined with short-term VLCDs has good protective effects on cardiovascular risk factors as a treatment intervention for IGT with obesity,as it could improve glycometabolism,significantly decrease the levels of blood pressure,blood lipids,BMI,WC and effectively cut-off and reverse the development of diabetes mellitus.