对无底柱分段崩落法两种改进方案的探讨

本文阐述了长端壁和隔层两种无底柱分段崩落法改进方案的特点、优点及其理论基础。这两种方案对于改善采矿损失率和矿山通风方面均有效益。     

Early-stage mineralization of hydrothermal tubeworms： New insights into the role of microorganisms in the process of mineralization

As an important part of marine hydrothermal system, hydrothermal vent faunas live in hydrothermal inorganic environment and closely interact with hydrothermal inorganic environment. Sometimes, they can participate in the mineralization process of modern hydrothermal site. Hydrothermal vent faunas, particularly vesUmentiferan and polychaete tubeworms, are occasionally preserved in the geological record. Study on the early mineralization process of hydrothermal vent fauna is significant for understanding the interaction between mineral and organism, and also the formation and preservation mechanism of geological fossil in hydrothermal environment. In this paper, the early stage of mineralization of Vestimentiferan Ridgeia piscesae tubes collected from Juan de Fuca Ridge is studied. The results showed that a lot of filamentous microorganisms were unevenly distributed on the surface of internal wall and in the interspace of the wall of tubeworm. In some cases, microorganisms aggregated as thin layers in or on the wall of tubeworm. The surfaces of microbial cells and the products of microbial degradation may play an important role in the early mineralization of tubeworm. Semitransparent thin layers of organic matter containing sulfur and sulfur granules were commonly found on the wall of tubeworm with lower degree of mineralization. The degradation production of these semitransparent thin layers may accelerate the mineralization of tube wall during the early stage. EDS results showed that on the tube walls some chemical elements such as Fe, P, Ca and Si are selectively enriched from ambient hydrothermal environment. Interestingly, P, Ca and Si covary with Fe content. Because element S originated from the bio-oxidation of H2S by symbiotic microorganism in the tissue of tubeworm, it can be considered as a biomarker when studying the mineralization process of tube wall. Based on the characteristics of tubeworms with different degrees of mineralization, we suggested that the early mineralization stage of tube wall was mai     

论普通地方高校新生不报到的现状及对策

高校招生考试制度的改革,招生规模的扩大,给普通地方高校带来了巨大的挑战,也使新生不报到现象更加突出。对此现状,本文着重从社会、学校及家庭等方面探讨其背后的深层原因,并据此从国家加强政策指导、学校加强自身特色与政策等方面提出解决对策。     

无门槽反钩闸门的设计与运用

介绍了一种新型闸门——无门槽反钩闸门,这种闸门布置形式可以有效减少空蚀破坏,最大限度地降低水头损失,避免空穴源的产生。     

玻璃窗泄爆下室内燃气爆炸荷载规律试验研究

建立了一套野外试验系统,设计了19组试验工况,分别研究了室内燃气浓度、泄爆窗玻璃破坏强度及面积对室内燃气爆炸荷载的影响,得到了玻璃窗泄爆条件下室内燃气爆炸的荷载特性和变化规律。试验研究结果表明：甲烷浓度在7.5%~10.5%时,室内燃气爆炸产生两个压力峰值,并引起声振不稳定燃烧,形成远大于第一个压力峰值的第二压力峰值;甲烷浓度较高时,声振现象不容易出现,只产生一个压力峰值,其大小仅与泄爆口封闭物有关;当甲烷气体浓度为9.5%时,燃气爆炸反应最剧烈,第一个压力峰值和声振压力峰值均为最大;提高泄爆窗玻璃破坏强度,会导致爆炸荷载的第一个压力峰值增大;增加泄爆窗面积,会使第一个压力峰值略微降低,但第二个的声振压力峰值则会大幅降低。研究结果有利于了解玻璃窗泄爆条件下室内燃气爆炸荷载规律和作用机理,并对进一步研究燃气爆炸荷载下结构的动力响应和破坏形态具有实际意义。     

高应力破裂岩体地压显现及其控制技术

小官庄铁矿进路开挖以后支护巷道破坏严重,其围岩变形为无收敛变形的情况.为掌握其地压活动规律,应用岩石破裂过程分析系统,并考虑岩石本身的蠕变特性,模拟其采用无底柱分段崩落法进路开挖过程,对进路开挖过程巷道围岩应力变化进行数值分析.结果表明:随着进路开挖,进路会出现片帮、底鼓和顶板下沉等现象;在矿岩接触带出现高应力集中,导致两进路之间的间柱破坏严重,并随着进路开挖应力逐步向新开挖两进路之间的间柱转移;开挖顺序造成边界矿体出现高应力集中,导致边界矿体难采.采用锚网支护技术有效地控制了巷道围岩的变形破坏,确保开采的顺利进行.     

无啮合力齿轮泵原理及其齿轮参数化设计

针对普通齿轮泵工作压力提高所带来的问题,介绍了无啮合力齿轮泵的结构原理,将啮合力与液压力分离.齿轮设计是保证同步齿轮与吸排液齿轮同步运转的关键,研究利用Pro/Engineer及其二次开发模块Pro/Toolkit,以Visual C++为开发平台,开发图形界面友好的用户对话框和应用程序,实现无啮合力齿轮泵齿轮参数化设计,避免了相似而复杂的结构给设计工作带来的重复性和繁琐性,提高了齿轮造型精确性和设计工作的效率,为无啮合力齿轮泵的进一步深入研究创造了有利的条件.     

实物交换决策

根据实物交换的现实意义,从交换双方对交换结果的满意程度出发,在保证双方交换后的满意度与初始满意度相比都不能降低的基本前提下,提出了实物交换的三种情况:1．双方满意度提高值之和最大;2．双方满意度提高值相等;3．偏向某一方且保证另一方满意度不能降低．并且用分析法确立了交换决策．对于第三种情况,交换决策可以用图解法清晰的表示．     

容量有限逻辑环网的两种服务方式及其比较

讨论了容量有限逻辑环通信网中的门限服务方式和非门限服务方式。文章阐明两种服务方式的运行特点并建立数字模型、通过计算机编程,在相同条件下比较两种方式的系统和队列的各种工作特性参数。文中还针对典例描绘出特性曲线并由此得出结论：非门限服务方式的系统性能略优于门了限服务方式的系统性能。