库板结构的高温箱的热变形计算讨论

根据金属材料热胀冷缩的物理特性．以及弦长与弧长的几何数量关系，定量地分析了在工厂中遇到的实际问题——大型库板结构高温箱的热变形问题。这对生产企业的设计人员采取何种措施．提高大型库板结构高温箱的设计质量，能起到一定的参考作用。     

内陆湿热地区机场环境谱编制

目的编制内陆湿热地区机场环境谱。方法分析影响飞机(直升机)日历寿命的地面主要环境因素,确定内陆湿热地区环境因素数据监测项目,以机场气象环境因素为基础,以现场测量化学环境因素为补充,编制机场环境谱,通过机场地区整体环境特性分析验证环境谱的有效性。结果机场环境均具有典型的内陆湿热地区非工业环境特点,大气腐蚀性等级中等(C3级)。结论量化了内陆湿热地区服役直升机面临的使用环境,为内陆湿热地区直升机环境适应性考核验证和腐蚀防护设计提供输入。     

山东苍山5.2级地震前苏北地区的地形变异常变化

客观地反映了1995年9月20日山东苍山5.2级地震前,发育在苏北地区的各类地形变异常,并进行了相应的分析相探讨,在总结研究前兆的基础上指出综合预报的重要性和在中期趋势异常背景中捕捉短临前兆的必要性。     

华北平原地下热水矿床分布规律及形成

我国华北平原分布有大小不等、形状各异的地下热水矿床;赋存于石灰岩地层形成的地质构造凸起部位的地下热水富水性好,井产水量大,自喷能力强,水质好,矿化度低,温度高,具有较高的开发利用价值。华北平原地下热水的热源与第三纪侵入的火成岩无关。地下热水的补给来源是山区大气降水渗入地下经过较大的构造断裂带和碳酸盐岩地层岩溶溶洞、断裂裂隙深循环以后形成的。地下热水的温度主要取决于水循环的深度。     

劈裂拉伸条件下大红山铜矿矿岩变形特性的试验研究

对大红山铜矿的3种岩石的试样进行了劈裂拉伸(巴西法)试验和单轴压缩试验,研究了岩石的变形特性。劈裂试验中在试样中部相互垂直的方向上粘贴了电阻应变计测量试样的变形。结果表明,在劈裂试验条件下,两种岩石均出现垂直于加载轴线方向所获得的拉伸弹模小于平行于加载轴线方向所获得的压缩弹模的现象。与单轴压缩下试样出现破裂、扩容的破坏特征相比,劈裂拉伸下试样的变形特征为接近峰值时变形曲线斜率会逐渐降低,达到峰值应力后则很快出现数值很大的拉伸变形,直至试样破坏。劈裂拉伸循环加卸载试验发现,大多数试样的拉伸卸载变形大于加载变形,致使残余变形的数值为负值,称之为反向残余变形。此现象与连续介质变形行为的预期不符,至今未见类似报道。反向残余变形是否具有普遍性及其影响,应该开展更多研究。     

白炭黑补强氟硅橡胶热空气老化机理研究

目的研究热空气老化过程中白炭黑补强氟硅橡胶的老化机理。方法开展不同加速老化温度点下白炭黑补强氟硅橡胶热空气老化试验,对老化过程中材料的力学性能进行研究,同时采用热重分析、衰减全反射红外光谱、交联密度分析以及固体核磁等技术,对200℃热空气老化过程中材料的微观结构变化进行分析。结果低温环境中白炭黑氟硅橡胶拉伸强度和扯断伸长率变化较小,高温环境中变化趋势增大,邵尔A硬度在整个老化过程中没有明显变化。结论白炭黑补强氟硅橡胶的老化机理主要是交联键的断裂和侧链三氟丙基的分解,同时还可能伴随有部分主链的破坏。     

Text analysis tools for identification of emerging topics and research gaps in conservation science

Keeping track of conceptual and methodological developments is a critical skill for research scientists, but this task is increasingly difficult due to the high rate of academic publication. As a crisis discipline, conservation science is particularly in need of tools that facilitate rapid yet insightful synthesis. We show how a common text‐mining method (latent Dirichlet allocation, or topic modeling) and statistical tests familiar to ecologists (cluster analysis, regression, and network analysis) can be used to investigate trends and identify potential research gaps in the scientific literature. We tested these methods on the literature on ecological surrogates and indicators. Analysis of topic popularity within this corpus showed a strong emphasis on monitoring and management of fragmented ecosystems, while analysis of research gaps suggested a greater role for genetic surrogates and indicators. Our results show that automated text analysis methods need to be used with care, but can provide information that is complementary to that given by systematic reviews and meta‐analyses, increasing scientists’ capacity for research synthesis.     

瞬态温度载荷下固液混合装药内部温度响应研究

为了研究瞬态温度载荷作用下固液混合装药起爆点火过程,设计了瞬态温度载荷试验装置和瞬态温度测试系统。用黑火药爆炸温度作为瞬态温度载荷,测试了固液混合装药内部的温度响应过程,并与数值模拟进行对比分析。结果表明,设计的瞬态温度载荷测试系统可以研究装药对瞬态温度的响应。     

Knowledge and Use of Biodiversity in Brazilian Hot Spots

Hot spots in Brazil include a variety of ecosystems, such as mangroves, forests, and the Brazilian savannah, locally called cerrado. Some of the rural populations in these hot spots are the caiçaras in SE Atlantic Forest coast, and the caboclos in the Amazon. In this study, we are concerned especially with the knowledge of caiçaras and caboclos, associated with practices that might have implications for management. Data were gathered through interviews with adults at the various communities studied, and through systematic observations, including samples of fishing trips and the mapping of fishing spots used in the Atlantic Forest coast. The use of resources from the surrounding vegetation includes collection of plants, cultivated fruit gardens, the swidden system, and a careful and managed extraction of fibres. Among animal resources, food taboos seem to be useful practices that might contribute to the maintenance of local natural resources. Potential management practices should be locally developed, such as the informal division of fishing spots in Atlantic Forest sites, and the maintenance of the diversity of cassava varieties in both the Atlantic Forest and Amazonian areas.     

考虑刚度劣化的剪切带-围岩系统稳定性分析

峰后的刚度劣化现象(渐进损伤)在多种煤、岩石、混凝土、土和砂子的循环加载实验中已被观察到。本文考虑了剪切带及带外弹性体的不同的刚度劣化现象,推导了剪切带(断层)-弹性围岩系统在直剪条件下的应力—变形曲线。剪切带的刚度劣化不改变剪切带的总变形,但使剪切带的弹性变形增加、塑性变形降低。考虑弹性体的刚度劣化现象之后,系统的峰后应力—变形曲线呈现非线性特征,这不同于过去忽略刚度劣化现象的结果。在应变软化过程中,剪切带之外弹性体的刚度劣化,使系统的峰后响应由负斜率(Ⅰ类行为)变为正斜率(Ⅱ类变形行为)。较高的弹性体尺寸、较高的脆性、较小的内部长度、较低的围岩初始弹性模量、较高的抗剪强度、较低的残余剪切应力及较高的残余剪切弹性模量,使系统的峰后响应变得陡峭,甚至发生Ⅱ类行为,使系统的失稳(岩爆、冲击地压、采矿诱发地震或矿震)易于发生。