我国证券市场体制性缺陷与投资风险分析

与国民经济长期高增长相背离,证券市场出现了深幅下跌,投资者承受了巨大的投资风险,究其原因,体制性缺陷是重要因素之一。笔者认为,我国证券市场的体制性缺陷主要表现在市场经济环境不够完备、法律法规体系不十分健全、监管体制不力、证券市场的功能定位扭曲、股权分置问题久拖难决等方面。目前该体制性缺陷是导致我国证券市场长期下跌的重要原因,也给证券投资者带来了巨大的投资风险。只有加快改革、完善法律和监管体制,我国证券市场才能具有投资价值并健康发展。     

不同构造措施的钢管混凝土边框钢板剪力墙抗震性能试验研究

钢管混凝土边框钢板剪力墙是一种新型抗震剪力墙,为了比较不同构造措施对该新型剪力墙抗震性能的影响,进行了3个剪跨比为1.5的钢管混凝土边框钢板剪力墙低周反复荷载试验.其中,试验模型1为墙体钢板与边框柱钢管焊接,试验模型2为墙体钢板与边框柱钢管螺栓连接,试验模型3为墙体钢板开孔并与边框柱钢管焊接.通过试验研究,比较了各剪力...     

黏土地层联络通道冻结壁厚度优化设计及应用研究*

为解决传统冻结壁设计方法不能真实、合理地反映黏土地层中联络通道冻结壁实际受力情况,进而导致冻结壁厚度设计过于保守的问题,结合黏土地层直墙拱形冻结壁实际受力特点,基于对冻结壁支护压力的合理计算,提出1种适用于黏土地层冻结壁厚度设计的优化方法。结果表明:与传统设计方法相比,该方法所确定冻结壁支护压力与实际施工环境中冻结壁受力状态吻合效果更好,并且能够提供合理的安全储备;经数值计算和现场应用验证,计算所得冻结壁设计方案可以满足施工环境中的承载力及变形稳定性要求;且相较传统设计方案,所得方案兼具安全性与经济性,可有效规避因设计过于保守和冻结周期过长引起的冻胀、融沉变形过大等工程灾害的风险;该方法高效、易行,可为传统冻结壁设计方法提供必要补充,亦可为类似工程的施工设计提供有益参考。     

不同给水管材对管壁附着生物膜铅、镉的解吸动力学研究

给水管壁生物膜会吸附水中的重金属元素积累在管壁生物膜中,在受到扰动时释放回到水体,危害饮用水水质安全。试验以上海管网末梢水为实验对象,研究了PVC、铸铁和紫铜等三种管材上生物膜对铅、镉的解吸特性。结果表明,PVC、铸铁和紫铜附着生物膜对铅的解吸容量qe分别为:5.92211μmol·m^-2、128.3051μmol·m^-2和21.1808,解吸速率常数k分别为:0.001060 m^2·μmol^-1·min^-1、0.000041 m^2·μmol^-1·min^-1和0.000503 m^2·μmol^-1·min^-1,对于镉元素三种材质的解吸容量qe分别为:14.71519μmol·m^-2、18.50481μmol·m^-2和2.25225μmol·m^-2;解吸速率常数k分别为:0.000102 m^2·μmol^-1·min^-1、0.001070 m^2·μmol^-1·min^-1和0.000103 m^2·μmol^-1·min^-1。     

垂直面绿化植物遮阳系数与叶面积指数研究

比较、分析了农业研究中提出的叶面积指数LAI与用于建筑节能领域的垂直面绿化植物叶片遮阳系数SCPVW两个概念的异同和各自的应用范围。指出城市绿化采用水平或垂直绿化方式时,由于下垫面差异,植物叶片的遮阳系数应当分别采用LAI和SCPVW进行计算。     

爆炸荷载作用下钢筋混凝土防爆墙动力响应研究

为了研究钢筋混凝土防爆墙的抗爆能力,采用有限元分析方法对不同纵向配筋率、不同高跨比、不同厚度的墙体在爆炸动态荷载作用下的动力响应进行研究,对各种不同设置的钢筋混凝土防爆墙的抗爆性能进行评估。结果表明:减小高跨比对提高钢筋混凝土防爆墙的抗爆能力最为重要,提高纵向配筋率,增加厚度都能增加防爆墙的抗爆能力。     

珠光体耐热钢膜式水冷壁制造工艺优化

本文简要介绍了膜式水冷壁管屏制作工艺过程和珠光体耐热钢水冷壁管屏制造过程中易产生的缺陷分析,通过改进优化成排弯曲模具,焊前清理、预热,避免外侧管椭圆度、焊接气孔、咬边等缺陷。结合工艺试验分析了珠光体耐热钢管屏热矫正后不恰当的冷却方式引起延迟裂纹的原因,从而总结出珠光体耐热钢水冷管屏焊后热矫正时需特别注意的加热方法、加热温度及冷却方式,确保产品质量。     

基于热湿交换理论的巷道风流温、湿度影响因素研究

为了研究巷道风流参数的影响因素、预测风流温湿度的变化规律,结合热湿交换理论,建立了风流与围岩壁面之间热湿交换的数学模型,以及贴体坐标系下围岩内部温度场的导热微分方程;利用数值方法,将围岩内部的导热问题与影响风流参数变化的热湿交换问题耦合起来,并以大柳塔煤矿52505综采工作面为例进行计算,得到了与实测参数较为一致的模拟结果,验证了该数值方法的有效性。研究结果表明:风流温度受原始岩温、入风流温度、局部热源强度等因素的影响,风流相对湿度与入风流温、湿度以及井下湿源的数量和强度有关;巷道壁温作为将围岩温度场与风流参数之间关联起来的主要因素,对模拟结果影响较大,其数值取决于壁面与风流之间热湿交换以及围岩原始岩温。     

Proposing of new building scheme and composite towards global warming mitigation for Malaysia

The building sector has been regarded as a potential sector where there is large capacity to reduce the climate change effect. This study has proposed solutions to mitigate environmental impacts and achieve low CO₂ emission from residential sector. Therefore, full life cycle assessment (LCA) has been run to assess the CO₂ emission and its effect on the atmosphere and climate change. Based on the result, timber scheme is the best choice due to releasing less CO₂ emissions to the atmosphere. However, house builders in Malaysia have almost completely neglected timber as a building material, with timber use as building components reduced to 5%. In this study, LCA Software was used to assess CO₂ emissions from different wall construction. The alternative building scheme has been made by reinforce steel stud, wooden beam and timber wall (S8) to improve the scheme deficiency while releasing less CO₂ emissions compared to other schemes. Therefore, S8 has a decreased CO₂ effect by 85% less than precast concrete frame and 90% less than brick over their lifetime. (S8) increased the load bearing compared to conventional timber beam. Thus, new scheme S8 could be replaced by current scheme and promote more adjustable scheme for Malaysian housing.     

Different effects of foliar application of silica sol on arsenic translocation in rice under low and high arsenite stress

Foliar application of Si can generally reduce As translocation from roots to shoots in rice; however, it does not always work, particularly under high As stress. Here, the effects of foliar application of nanoscale silica sol on As accumulation in rice were investigated under low (2 μmol/L) and high (8 μmol/L) arsenite stress. The results revealed that foliar Si application significantly decreased the As concentration in shoots under low arsenite stress, but showed different effects under high arsenite stress after 7 days of incubation. The reduction in root-to-shoot As translocation under the 2As+Si treatment was related to the down-regulation of OsLsi1 and OsLsi2 expression and up-regulation of OsABCC1 expression in roots. In the 8As+Si treatment, the expressions of OsLsi1, OsLsi2, and OsABCC1 were significantly promoted, which resulted in substantially higher As accumulation in both the roots and shoots. In the roots, As predominantly accumulated in the symplasts (90.6%–98.3%), in which the majority of As was sequestered in vacuoles (79.0%–94.0%) under both levels of arsenite stress. Compared with that of the 8As treatment, the 8As+Si treatment significantly increased the As concentration in cell walls, but showed no difference in the vacuolar As concentration, which remained constant at approximately 69.1–71.7 mg/kg during days 4–7. It appeared that the capacity of root cells to sequester As in the vacuoles had a threshold, and the excess As tended to accumulate in the cell walls and transfer to the shoots via apoplasts under high arsenite stress. This study provides a better understanding of the different effects of foliar Si application on As accumulation in rice from the view of arsenite-related gene expression and As subcellular distribution in roots.