卫星伸展机构的图示评审技术应用

目的解决卫星伸展机构参数表现形式多样且不确定的问题。方法运用图示评审技术,构建MU-GERT网络模型,并将参数统一用广义灰数表征。考虑解析算法的复杂性,提出针对该网络模型的矩阵式表征方法,并设计出矩阵式求解算法,便于运用计算机编程进行准确快速的求解。结果用MU-GERT网络模型计算概率不确定时制作一个合格卫星伸展机构需要的时间,仿真模拟出制作出一个合格卫星伸展机构的期望与机会。结论为图示评审技术在卫星伸展机构研制中的应用提供了研究思路和经验借鉴。     

基于MATLAB的火灾探测报警系统寿命分布和可靠度研究

基于不同的系统可靠性寿命分布类型对应的可靠度模型,介绍4种常见的系统可靠性寿命分布模型的适用情况、特征、规律。根据概率论和数理统计相关理论,研究在MATLAB下判断系统寿命分布模型的方法,利用MATLAB函数对模型参数进行估计,构建系统可靠度模型。并以某商场的火灾探测报警系统作为研究对象,收集一段时间的系统故障数据,运用MATLAB数值分析方法,得出火灾探测报警系统的可靠度模型,找出系统可靠度随使用寿命的变化规律。结果表明:计算得到的商场火灾探测报警系统的可靠度随着使用时间变化规律与实际情况基本吻合。     

某RDX基浇注PBX的加速老化规律与寿命评估

目的掌握环三亚甲基三硝胺(RDX)基浇注高聚物黏结炸药(PBX)的加速老化规律,分析老化机理和关键敏感参量,并探讨加速老化寿命评估方法。方法针对RDX基浇注PBX开展60、70、80℃等恒定温度下的加速贮存老化试验,采用微焦点X射线计算机断层扫描仪(微焦点CT)、核磁共振、气相色谱等方法,分析浇注炸药在老化过程中微孔隙率、交联密度以及增塑剂含量等结构参量的变化规律,通过对这几种参量的对比,分析其老化机理,并进一步对加速老化寿命评估方法进行初步探讨。结果浇注PBX在加速老化过程中会出现明显的孔隙率逐渐增加、交联密度逐渐增加以及增塑剂逐渐降低等问题,且表现为温度越高,相关性能参量变化得越快。鉴于增塑剂含量的降低理论上会导致孔隙率增加,且增塑剂具有降低感度的作用,对于侵彻安定性具有较大的影响,且增塑剂含量的表征方法简便,以增塑剂含量作为浇注PBX的敏感参量,采用阿伦尼乌斯模型,对浇注PBX的寿命进行了评估。结论RDX基浇注PBX在加速老化过程中孔隙率、交联密度以及增塑剂含量会出现较为明显的变化,可作为性能评价的敏感参量。以增塑剂含量作为敏感参量,以增塑剂含量降低10%为判据,推导出RDX基浇注PBX的寿命约为14.5 a(25℃)和23.8 a(21℃)。     

盾构隧道全寿命防水风险模糊评价

在对盾构隧道进行防水风险等级划分和主要风险因素识别的基础上,对风险因素进行合理模糊化,利用模糊识别理论研究了盾构隧道全寿命防水风险评价,所提方法能一定程度上客观、量化地评价盾构隧道全寿命防水风险,所提方法对其他类似工程项目的风险评价具有借鉴意义.     

燃煤电厂电除尘改造技术及应用

简述了我国燃煤电厂电除尘器的现状,概述了我国燃煤电厂电除尘器改造的一些主要技术路线,并重点分析了宝钢自备电厂电除尘采用高频电源结合本体扩容的改造案例。     

基于物元可拓的熵值泥石流危险性评价

通过选取能够反映和体现泥石流危险性的8项重要参数指标作为泥石流危险性评价指标,运用物元可拓理论和熵值确定权重法,建立泥石流危险性评价的物元可拓模型。应用建立的物元可拓模型,对舟曲县15条典型泥石流沟的危险性进行评价,得到的评价结果与实际情况相符合,同时也说明基于物元可拓的熵值法能较真实地反映实际泥石流沟的危险性等级,证明该方法应用于泥石流危险性评价的有效性和可行性。     

Preparation and photocatalytic properties of porous C and N co-doped TiO2 deposited on brick by a fast, one-step microwave irradiation method

A one-step microwave irradiation method was used to deposit carbon and nitrogen co-doped TiO_2((C, N)-TiO_2) on commercial brick((C, N)-TiO_2/brick). The as-prepared samples were characterized by X-ray diffraction, ultraviolet–visible(UV–vis) diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy(SEM). A selective technique was also used to investigate the concentration of hydroxyl radicals during UV–vis irradiation of the Methyl Orange solution with the as-prepared samples. The C and N dopants enhanced visible light absorption and provided a longer lifetime for the photo-generated electron–hole pairs. The SEM images showed that the as-prepared sample is porous. The dark adsorption and photodegradation test for(C, N)-TiO_2/brick showed good photodegradation and good recyclability. The best photodegradation rate was 94% after 2 hr. The maximum degradation rate was maintained even after the 6th cycle. The good photocatalytic properties are attributed to the enhanced visible light absorption, enhanced pollutant adsorption arising from the porous structure of the(C, N)-TiO_2 thin film, and longer lifetime of the photo-generated electron–hole pairs.(C, N)-TiO_2/brick should have potential commercial applications in photodegradation processes because of its low cost, good photodegradation, and excellent recyclability.     

Assessment of health risk from organochlorine pesticides residues in high-fat spreadable foods produced in Poland

Currently, butter and margarine are food products attracting wide customer interest. Every day, consumers around the world buy these products for human consumption. Butter is obtained from milk fat, while margarine is derived from vegetable oils. The content of organochlorine pesticide (OCP) residues was examined in both types of these high fatty products. A gas chromatograph with MSD (HP 5973) detector was used for the determination of pesticides such as α-HCH, β-HCH, γ-HCH, DDT, DDD, DDE, aldrin, dieldrin, endrin, heptachlor and heptachlor epoxide. The examined products had diverse concentrations of the analyzed compounds. Visible was the division based on the origin of the product, which might be composed of animal or vegetable fats. The research has revealed the presence of OCP residues in all examined spreads. Quantities of organochlorine compounds did not pose an immediate danger to the consumers’ health. Human and environmental health risk assessment was carried out by the estimation of lifetime average daily dose (LADD) and non-carcinogenic health hazard quotient (HQ). Total estimated LADD ranged between 1.3 × 10^?5 and 3.1 × 10^?5 mg kg^?1 d^?1 for butter, and 1.9 × 10^?6 and 4.6 × 10^?6 mg kg^?1 d^?1 for margarine and mix spread. The HQ ranged between 1.1 × 10^?4 and 3.7 × 10^?4 for butter, and 1.4 × 10^?5 and 9.0 × 10^?6 for margarine and mix spread for adults. These estimated HQs were within the safe acceptable limits, indicating a negligible risk to the residents of the study area.     

The Future of Tropical Species on a Warmer Planet

Abstract: Modern global temperature and land cover and projected future temperatures suggest that tropical forest species will be particularly sensitive to global warming. Given a moderate greenhouse gas emissions scenario, fully 75% of the tropical forests present in 2000 will experience mean annual temperatures in 2100 that are greater than the highest mean annual temperature that supports closed‐canopy forest today. Temperature‐sensitive species might extend their ranges to cool refuges, defined here as areas where temperatures projected for 2100 match 1960s temperatures in the modern range. Distances to such cool refuges are greatest for equatorial species and are particularly large for key tropical forest areas including the Amazon and Congo River Basins, West Africa, and the upper elevations of many tropical mountains. In sum, tropical species are likely to be particularly sensitive to global warming because they are adapted to limited geographic and seasonal variation in temperature, already lived at or near the highest temperatures on Earth before global warming began, and are often isolated from cool refuges. To illustrate these three points, we examined the distributions and habitat associations of all extant mammal species. The distance to the nearest cool refuge exceeded 1000 km for more than 20% of the tropical and less than 4% of the extratropical species with small ranges. The biological impact of global warming is likely to be as severe in the tropics as at temperate and boreal latitudes.     

自然灾害基本定义的探讨

自然灾害的研究,正在变为一门热门的学科.然而,大多数人是通过举例来回答"什么是自然灾害?"这一问题,一些学者则干脆对此避而不谈.显然,如果对"自然灾害"这一概念没有严格的定义,如果人们只热衷于提出各种概念模型,热衷于案例分析,则"自然灾害学"就很难上升为一门科学内核清楚的学科.从分析定义的本质人手,梳理出下定义的4条规则,指出了现有5个自然灾害定义的不足之处,建议了一个自然灾害的基本定义,并用它分别对<国家综合减灾"十一五"规划>中提及的13种自然灾害进行了界定.