高耸建筑物定向爆破中切口长度安全范围的研究

爆破拆除高耸筒体结构时 ,爆破切口长度的合理选取是爆破成功的重要因素。目前的实践经验 ,爆破切口长度取为切口处筒体圆周长的 6 0 %～ 6 6 % (即 3/ 5～ 2 / 3) ,按此取值范围进行施工 ,爆破效果的好坏并存 ,事故仍有发生 ,这说明此取值范围偏大。借助有限元软件ANSYS ,通过数值计算 ,可获得起爆瞬间 ,在结构自重作用下引起的爆破切口支撑部的应力与应变状态 ,因而 ,可分析出爆破切口长度较安全的取值范围。对比实际拆除爆破的效果 ,爆破切口长度取切口处筒体圆周长的 6 2 %～ 6 4 %是比较安全适宜的。数值分析所得出的结论 ,对爆破设计施工有一定的借鉴意义     

一种新型宽带移动终端天线设计方案

针对当前无线通信中的终端天线应用进行研究,提出了一种新型的宽带微带天线结构,并采用了高频电磁场仿真软件进行了仿真验证和实际样品测试。结果表明,该天线可在0.816GHz~1.099GHz频段和1.657GHz~2.260GHz频段内达到要求的驻波比,可以实现GSM850/900/1800/1900频段以及WCDMA2100频段的要求。同时该天线结构整体辐射性能好,具有全向辐射性,适合移动终端使用。     

考虑松动圈影响的钻孔瓦斯抽放合理封孔长度确定研究

以王行庄矿11071工作面为工程试验地点,通过超声波和钻孔窥视现场测试,结合理论计算,开展了瓦斯抽采煤巷松动圈范围和瓦斯抽放钻孔合理封孔长度确定的研究。确定了王行庄11071工作面二1煤层围岩卸压区宽度为8.87 m,极限平衡区宽度为9.87 m,合理封孔深度为10 m;通过极限平衡法理论计算得到的结果与超声波法、钻孔窥视法的测试结果基本相符。     

铜胁迫对不同基因型谷子幼苗基因组DNA多态性的影响

采用室内盆栽土培法,以4种基因型谷子(D2-8、安06、黄米、朝谷)为供试材料,研究了不同浓度Cu2+胁迫对谷子幼苗体内可溶性糖、脯氨酸、丙二醛(MDA)含量和基因组DNA多态性的影响.结果表明,经50~400 mg·kg-1Cu2+处理30 d后,4种谷子幼苗体内可溶性糖含量与对照相比呈现先上升后下降的趋势,在50 mg·kg-1时达到最大值.当浓度为200mg·kg-1以上时,4种谷子的可溶性糖含量的平均降幅为对照的32.44%~56.5%.脯氨酸则表现为低含量(≤50 mg·kg-1)的促进和高含量(≥100 mg·kg-1)的抑制效应,MDA含量均有增加且与对照差异显著(P<0.05).Cu2+胁迫下不同基因型谷子幼苗基因组DNA的RAPD图谱发生明显变化,表现为单条或多条RAPD谱带的增加和缺失或者荧光强度的改变,细胞中基因组模板DNA的稳定性下降,DNA多态性变化与Cu2+浓度之间存在剂量-效应关系.不同基因型谷子对Cu2+胁迫的生理和遗传损伤响应存在差异.利用RAPD技术获得的DNA多态性变化可作为检测Cu2+遗传毒性效应的生物标记物.     

分光光度法中不同光程长度比色皿间关系验证

参照《纳氏试剂分光光度法》的方法原理,用分光光度计对3种光程长度比色皿分别进行比色,探讨不同光程长度比色皿间关系。     

散装液体危化品浮式码头金属软管失效原因分析及对策

介绍了金属软管在码头装卸船管路系统中的作用,并结合散装液体危化品浮式码头的实际,深入探讨了码头金属软管的失效原因,并提出了相应的防范措施,对提升金属软管的安全服役水平具有借鉴意义。     

张弦网壳结构索张拉模拟计算及试验研究

施工张拉控制是张弦网壳结构的关键技术之一,提出采用控制索原长的反分析方法追踪结构施工整个过程。首先,通过控制索在预应力状态下的张拉力求出零状态和索原长,并同时获得预应力态下所有单元的内力。在此基础上,通过控制每一级张拉索的原长,进行非线性有限元迭代计算,可求出索在分级分批施工时的控制力,并用VC＋＋6.0编制相应的计算程序。这一方法有效地避免了通用有限元需要反复试算,计算繁琐的缺点。最后,以张弦网壳结构模型为试验对象,按分级分批张拉的方式模拟结构的现场施工,并跟踪施工过程中杆件单元的应力状态。结果表明,数值模拟计算与试验值吻合较好,计算结果可靠,该方法能精确模拟结构的施工成形过程,且在整个过程中,每根索只需张拉一次,简化了施工工艺。     

Specific features of phenetic structure of the terrestrial snail <Emphasis Type="Italic">Cepaea vindobonensis</Emphasis> (Pulmonata; Helicidae) in urbanized and natural populations

The phenetic structure of natural and urbanized populations of the terrestrial snail Cepaea vindobonensis has been studied with respect to polymorphism in the shell-band color and pattern. It is noted that C. vindobonensis snails populating different artificial habitats in the city of Nikolaev and its suburbs are characterized by a higher level of both intra-and interpopulation diversity with respect to the type of this polymorphism. In addition, urban populations show a very wide range of variation in the frequencies of particular morphs or their groups. Conversely, natural populations are characterized by a more uniform frequency structure with respect to polymorphism of the shell banding pattern.     

Primary neuronal-astrocytic co-culture platform for neurotoxicity assessment of di-(2-ethylhexyl) phthalate

Plastics such as polyvinyl chlorides （PVC） are widely used in many indoor constructed environments; however, their unbound chemicals, such as di-（2-ethylhexyl） phthalates （DEHP）, can leach into the surrounding environment. This study focused on DEHP＇s effect on the central nervous system by determining the precise DEHP content in mice brain tissue after exposure to the chemical, to evaluate the specific exposure range. Primary neuronal-astrocyte co-culture systems were used as in vitro models for chemical hazard identification of DEHP. Oxidative stress was hypothesized as a probable mechanism involved, and therefore the total reactive oxygen species （ROS） concentration was determined as a biomarker of oxidative stress. In addition, NeuriteTracer, a neurite tracing plugin with ImageJ, was used to develop an assay for neurotoxicity to provide quantitative measurements of neurological parameters, such as neuronal number, neuron count and neurite length, all of which could indicate neurotoxic effects. The results showed that with 1 nmol/L DEHP exposure, there was a significant increase in ROS concentrations, indicating that the neuronal-astrocyte cultures were injured due to exposure to DEHP. In response, astrocyte proliferation （gliosis） was initiated, serving as a mechanism to maintain a homeostatic environment for neurons and protect neurons from toxic chemicals. There is a need to assess the cumulative effects of DEHP in animals to evaluate the possible uotake and effects on the human neuronal system from exoosure to DEHP in the indoor environment.     

Fouling distribution in forward osmosis membrane process

Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis （FO） membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic （alginate） fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter- current flow operation of FO membrane process.