Thermal conductivity measurement of the epoxies and composite material for low temperature superconducting magnet design

The thermal conductivities of solid materials were measured by a G-M cryo-cooler based apparatus in the temperature range of 2.6–21.0 K. The performance of this apparatus was verified by measuring the thermal conductivity of 304-stainless steel, and good reproducibility as well as accuracy was shown when compared with the certified values. The thermal conductivities of EC1017 and Stycast2850FT and a composite material were measured. Similar behavior to amorphous materials was shown for EC1017 and Stycast2850FT in that there was an apparent plateau, which could be ascribed to a very lower crystallinity of epoxy. An equivalent model was proposed to predict the thermal conductivity of the composite material.     

Small-scale experiments of self-sustaining decomposition of NPK fertilizer and application to events aboard the Ostedijk in 2007

Small-scale experiments to investigate the self-sustaining decomposition (SSD) behaviour of NPK 16.16.16 fertilizer have been undertaken. These experiments show that this material will undergo self-sustaining decomposition and are used to give insight into the behaviour of the reaction. A three-step decomposition process is observed leading to a self-sustained reaction reaching temperatures of 200–350 °C. The measured heat of reaction is 0.73–1.8 MJ/kg. Measurements are applied to the events that occurred aboard the ship Ostedijk in 2007 in which a SSD reaction occurred. The mass loss rate from the cargo was calculated to range from 0.5 kg/s on the first day to 12 kg/s on the last day. From this measurement, the maximum fire size was estimated to be in the range 5.8–29 MW.     

Effects of repeated exposures to severely cold environments on thermal responses of humans

Abstract

This study was conducted to investigate the effects of different exposure rates on thermal responses with the total cold exposure time the same under each of the conditions. After resting in a warm room (25°C) for 10 minutes, six male students wearing standard cold protective clothing entered an adjoining cold room (— 25°C). Each 5-, 10- and 20-minute cold exposure was repeated 12, 6 and 3 times, respectively. Each cold exposure was followed by a similar duration of rest at 25°C. Total cold exposure time was the same under the three conditions. Rectal temperature, skin temperatures, blood pressure, 17-hydroxycoyticoids (OHCS), counting task and subjective responses were measured. At the end of the cold exposure skin temperatures in the shorter exposures were higher than those in the other conditions, except on the foot. Discomfort due to cold was less in the shorter exposures and manifestation of discomfort was delayed. However, there were no differences among the three conditions in the fall of rectal temperature and urinary excretion of 17-OHCS, which are good indices of cold stress, Moreover, increase in blood pressure and decrease in counting task due to cold were not different among the three conditions. Even though the cold exposure time for each stay was short, when cold exposures were repeated frequently, cold stress of the whole body and decrease in manual task performance were the same as in the longer cold exposure.     

Synthesis of WSi2 -SiC composite under the thermally activated combustion mode

Opportunities on combustion synthesizing the WSi2-SiC ceramic composites in a wide range of compositions under the thermal activated mode were studied. Tungsten, silicon powders and carbon black were used as initial reagents, and Magnesium–Teflon mixture was used as an activating additive. The stepwise character of the combustion process evolution, being characterized by low- and high-temperature regimes, was revealed. The end-products were subjected to SEM, XRD and DTA/TG analyses.     

关于冶金机械设备几种事故驱动方式的比较

比较了冶金机械设备在停电故障下几种事故驱动方式,重点介绍了新兴的EPS(Emergency Power Supply)事故驱动电源,并倾向于采用EPS作为冶金设备的主要事故驱动。     

浅淡漳州市住宅外墙保温施工

漳州的气候条件对于建筑节能来说,主要是夏季隔热的问题,本文对漳州目前采用的住宅外墙保温施工的问题进行了粗浅的探讨。     

Could sperm quality be affected by a building environment? A literature review

The human body responds psychologically and physiologically to the thermal environment to which it is exposed. Fanger's PMV model has been adopted for the design of built environments and building maintenance from the end of the 1960s. The sperm quality of humans has been decreasing since the 1970s. The thermal environment is one of the most important factors of the Sick Building Syndrome (SBS). It is well known that spermatogenesis is very sensitive to heat exposure. Mild thermal exposure increases tissue microcirculation and consequently produces an appropriate supply of nutrients and oxygen to tissue cells; thus, it can modulate the proliferation of Sertoli cells in which the spermatogonia stem cells develop into adult spermatozoa. Excessive exposure to heat is harmful to spermatogenesis, and excessive testicular cooling can cause the cessation of spermatogenesis.     

焊接配电系统无功补偿主接线的分析

介绍了焊接配电系统无功补偿的主要特点和补偿电容器的两种主接线方式，分析了两种主接线各自的优缺点。     

南方电网交直流系统的简化方法

为了在PSCAD/EMTDC中搭建南方电网交直流系统,研究南方电网交直流动态特性,提出了简化南方电网大规模交直流系统的方法。该方法保留交直流系统中500 kV电压等级的主干网架、直流线路以及直流换流站与主干网架的交流通道,而对交流系统220 kV及以下电压等级的低压网络进行简化等值。具体包括以下步骤:首先对主干网架上的500 kV母线进行无误差的简化;然后对系统中所有500 kV母线进行扫描,确定每个500 kV母线所连的低压网络;最后对每个500 kV母线下的低电压等级网络进行简化,对等值发电机和负荷的动态参数进行聚合。使用文中所述方法对南方电网交直流系统进行简化。动态仿真结果及误差分析验证了该方法的有效性。