确定压力容器安全系数原则

压力容器安全系数与材料参数紧密相关,确定材料许用应力值时,需要同时考虑材料抗拉强度和屈服强度更为合理;奥氏体不锈钢材料具有非常好的应变强化能力和韧性,为充分发挥奥氏体不锈钢材料优良性能,选取奥氏体不锈钢材料许用应力值时,需要特殊考虑。压力容器安全系数的选取建立在经验基础上,在保障压力容器安全性前提条件下,为节省材料和降低成本,随着理论研究深入和科学实验的进步,压力容器安全系数有所降低,这是科学设计和实用成功经验结合的结果。     

煤与瓦斯突出的物理模拟和数值模拟研究

利用自行设计的实验装置,通过现场采集具有突出倾向的煤样,分别向实验装置煤样中充入吸附能力较大的CO2和吸附能力较小的N2来模拟不同级别的煤与瓦斯突出现象,物理试验结果表明:瓦斯压力越大,突出强度越大;当瓦斯压力相近时,吸附和解吸能力大的瓦斯突出强度大。通过数值模拟对煤与瓦斯突出进行研究,数值模拟再现了煤矿开采过程中诱发的煤与瓦斯突出全过程,同时验证了煤与瓦斯突出是瓦斯压力、地应力及煤岩体的力学性质综合作用的结果,该验证对进一步深入理解认识煤与瓦斯突出的机理具有重要的理论和实践意义。     

浸水冷应激对雏鸡某些酶活性及消化道粘膜充血的影响

以海兰雄性雏鸡为试验对象,研究急性浸水冷应激对健康雏鸡某些酶活性消化道粘膜充血的影响。结果表明：雏鸡在浸水冷应激后血清肌酸激酶（CrK）呈一致性升高趋势;而丙氨酸氨基转肽酶（ALT）的活性则在冷应激后15min明显升高（P＞0.05）,而后降低,至120min时又恢复致冷应激前水平,雏鸡血清乳酸脱氢酶（LDH）在冷应激后15－60min呈渐进性升高,而后降低;血清γ－谷氨酰转肽酶（γ－GT）的变化趋势为,在冷应激后15min稍升高,而后则逐渐下降;血清尿素氮（BUN)的变化无是,在冷应激后60min降低,浸水应激后不同时间对海兰雏鸡消化道粘膜充血的结果表明：雏鸡在浸水应激后即刻观察造成消化道充血现象并不严重;而浸水应激后不同时间却对雏鸡消化道产生相对较强的影响,特别是冷应激后1－2h胃肠道充血比较严重。     

试用模糊数学方法对电焊作业防护措施进行综合评价

选择北京市四家锅炉厂的电焊工５６名，即从事手把焊、氩弧焊、ＣＯ２气体保护焊、电弧气爆等特种工种作业人员。通过调查，提出单项四级评分标准，再依模糊数学模型，进行综合评价。按Ｂ＝Ａ·Ｒ，求得Ｂ中最大元为０．７０７。最后总评为甲级。此结果与权数分配有关。此方法，可为劳动卫生管理（防护措施评级）提供依据。     

顺倾山体采空侧滑致灾的复合应力场研究

本文分析了地下采空情况后认为，山体采空侧动，软弱夹层为决定性条件；其变动范围、速率、规模与性质，与地下采空有关的复合应力场有关。经对观测资料分析、仿真模型试验与仿真数值模拟的对比研究，揭露了顺倾山体的“复合临空面”条件下，“复合变动”的“复合应力场”。     

用固体力学化学理论研究岩土的力学化学行为——以成都龙泉紫色土为例

根据固体力学化学理论 ,提出用化学动力学方法研究岩土破坏及滑坡形成的机理 ,并以成都龙泉紫色土为例研究了在力与水协同作用下易滑土层的力学化学行为。实验表明 ,土长期抗剪强度降低的幅度与溶液的pH值有关 ,土的溶解速度与易溶盐含量有关 ,且溶解曲线略呈“S”型。这初步证明了龙泉紫色土破坏的力学 化学效应及其可能存在的自催化趋势。通过实验了解了力与水协同作用导致土破坏的力学化学规律 ,并将定量求解滑面长期抗剪强度与反应机理研究结合起来 ,为定量评价地下水和应力对岩土破坏机理这一滑坡学关键问题打下基础。     

火灾后钢筋混凝土损伤程度的灰关联分析

由于火灾对钢筋混凝土结构的影响存在不确定性,使得人们不能准确地确定火灾后钢筋混凝土结构的损伤程度,给评估和加固修复带来很大困难。本文运用灰色系统理论中灰关联分析数学模型定量分析了高温下钢筋混凝土梁的3种影响因素,并确定了各因素间的主次关系,为高温后钢筋混凝土结构的安全评估及修复加固提供了理论依据。     

ACUTE RESIDUAL TOXICITY OF SEVERAL DISINFECTANTS IN DOMESTIC AND INDUSTRIAL WASTE WATER1

ABSTRACT: This study determined the acute toxicity of waste water disinfected with chlorine, bromine chloride, or ozone. The residual toxicity of effluent dechlorinated with sulfur dioxide was also tested. Toxicity tests were conducted with cyprinid, salmonid, and centrarchid fishes, as well as several species of fresh water macroinvertebrates. Residual chlorine exhibited the greatest toxicity of the disinfectants tested; dechlorination with sulfur dioxide effectively eliminated the toxicity of chlorinated effluent. Residual ozone produced mortality in test animals only under special conditions where subjects were exposed to effluent immediately after it was contacted with ozone, and chlorobrominated effluent was more toxic to salmonids than chlorinated effluent.     

THE DEPENDENCE OF THE RESIDUAL GRAVITY ON HYDRAULIC CONSTANTS IN GLACIAL DEPOSITS1

ABSTRACT: Buried glacial stream channels contain large and easily accessible groundwater resources. Gravity surveys have been frequently applied for their location. A gravity survey in the geohydrologically explored Wood River Valley Area of southern Rhode Island shows extreme lows of -2 mgals over channel depths of maximal 300 feet. Three gravity profiles were observed in east-west direction across a north-south striking stream channel. The bedrock depth increases rapidly towards the south from 130 to 300 feet. The gravity lows observed across each profile are not related to the bedrock depth but rather to the saturated thickness of the main quifer and its hydraulic transmissivity. Well logs indicate that the large change of bedrock depth is solely due to an increase of till of low permeability. The volume of the glacial outwash, which is the major groundwater resource, changes little underneath the three profiles. The gravity lows apear to be directly related to the density contrast between glacial outwash and till. The response to the hydraulically more pertinent units renews the interest in the gravity method as it may have a potential to estimate yields of hydrologically complex aquifers