Bianchi Type-1 vacuum models in modified theory of general relativity     

R.C. Sahu  U.K. Panigrahi 《Astrophysics and Space Science》2003,288(4):499-508

In this paper, the problem of spatially homogeneous and an isotropic Bianchi type-1 space time with perfect fluid distribution is considered in Barber's second theory of gravitation. To obtain determinate solutions, we have assumed the equation of statep= γρ, 0 ≤ γ ≤ 1. It is observed that the general fluid distribution degenerates isotropic vacuum model whenγ = 1 and Λ < 0. Further it is observed that the vacuum model obtained in case of γ = 0, ρ = 0 andΛ = 0, reduces to well known Kasner model in Einstein's theory. Some physical and geometrical aspects of the models together with singularities in the models are also discussed This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

三种降低土料含水量方法的试验研究     

张林洪  吴华金  王甦达 《岩土工程技术》2007,21(4):170-175

从原理分析,采用疏干排水、真空排水、电渗排水都能排除土料中的水分。为了确定能否在工程中使用,对三种方法进行试验。三种方法开始时排水速率较快,都能降低土体的含水量,提高土体密度。得出电渗方法排水效果最好。  相似文献   

真空加固前后软土工程地质性质研究   总被引：1，自引：1，他引：1  

秦焱  王清  侯红英 《世界地质》2007,26(1):89-93

借助X-射线、扫描电镜及计算机图像处理等技术，对海积软土真空预压加固前后的结构特征进行定量分析，并结合室内试验，对比研究土体微观结构和工程性质的变化，探讨真空预压加固的机理。研究表明真空预压加固效果明显，软土工程性质得到改善。加固前软土的微结构以蜂窝状、团粒-絮凝状结构为主，大孔隙较多；加固后以团粒状结构为主，粒内和粒间孔隙变小；加固后结构单元体和孔隙未形成明显的定向性。这与堆载预压加固的结构变化显著不同。真空预压加固是在球应力即等向压力下固结。  相似文献   

Fe2O3-TiO2复合光催化剂的制备及其对染料酸性大红降解的光催化活性研究   总被引：1，自引：0，他引：1  

彭书传 袁君庆承松  陈菊霞高薇龚潇  陈天虎 《岩石矿物学杂志》2007,26(5):462-466

以氧化铁红粉末为载体,钛酸四丁酯为前驱体,无水乙醇为溶剂,制备了Fe2O3-TiO2光催化剂。用XRD、TEM等对催化剂的物相、形貌进行了表征,并通过对酸性大红GR染料废水进行光催化降解实验,研究了催化剂的投加量、光照时间以及起始浓度、pH值、回收方法及催化剂重复使用次数对酸性大红染料废水光降解作用的影响。实验结果表明,氧化铁红粉末负载TiO2催化剂有很好的吸附和光催化性能,并可以多次回收重复使用,在投加量为0.4g/L的条件下,光催化效果最好,1h后的脱色率可达95%以上。  相似文献   

脑膜瘤旁巨型矿化灶矿物成分分析     

杨若晨王长秋  柳剑英鲁安怀张波  顾建文马原 《岩石矿物学杂志》2007,26(6):597-601

脑膜瘤旁复发性巨大矿化灶是罕见的病例,对其中矿物成分的分析可能会对肿瘤复发病因的研究提供辅助信息。本文利用X射线物相分析、红外光谱分析、环境扫描电镜观察和高分辨透射电镜观察分析等方法,对该矿化灶样品的矿物成分进行了分析。结果表明,该矿化灶的矿物颗粒大小统计值约为4.3nm,主要成分为碳酸磷灰石,笔者推测可能还含有少量不定形的磷酸钙系列其他矿物。  相似文献   

X射线荧光光谱法测定地质样品中的氯和硫     

袁家义  白雪冰王卿 周长祥 《岩矿测试》2004,23(3):225-227

使用粉末压片-X射线荧光光谱法测定地质样品中的Cl和S，探讨了样品放置时间、环境以及建立真空的时间对测量结果的影响。Cl的精密度(RSD，n=6)小于10％，S的精密度(RSD，n=6)小于5％。Cl和S的方法检出限分别为14和11μg／g，采用国家标准物质分析验证方法，其结果与标准值相符。  相似文献   

真空预压作用下软土地基固结的分形研究     

吴春勇  王清  吕洪斌 《探矿工程》2005,32(12):6-9

随着真空预压法在软土地基处理中的逐步应用，其软土固结的机理一直是探讨的课题，分形理论的产生为软土这一非线性系统研究提供了新的思路。针对真空预压作用下软土地基固结中存在的问题以及土体研究中的一些分形现象，用分形理论对其研究前景等进行了探讨，从宏观和微观两方面论证了真空预压作用下软土地基固结的分形研究是可行的。  相似文献   

真空-堆载联合预压法应用试验研究     

彭劼  施麟丽  陆玉琳 《上海国土资源》2005,5(4):34-37

对杭金衢高速公路真空-堆载联合预压工程，进行了现场试验和资料分析研究。研究表明真空预压能使地基产生较大的沉降速率，同时产生向内的水平位移，从而使真空一堆载联合预压比超载预压具有更强的抗失稳能力，侧向位移量和位移速率与荷载大小有明显的相关性。真空预压的加固深度主要是竖向排水体范围内，而真空-堆载联合预压法的加固深度则可根据堆载的附加应力比来确定。  相似文献   

Dechlorination of trichloroethylene in solution over supported nano zero valent Fe and Cu/Fe bimetal on exfoliated graphite     

Huan ZHANG Zhaohui JIN Lu HAN Zongming XIU Chenghua QIN 《中国地球化学学报》2006,25(B08):132-133

Degradation of organic halides by reductive dehalogenation promoted by zerovalent metals is a very active research area. The use of nano-sized particles of zero valent iron （ZVI） or bimetallic combinations of ZVI currently attracts the most attention due to their high surface areas and high reactive activity. The introduction of second catalytic metals, such as Pd, Pt, Cu, or Ni, results in an even higher dehalogenation rate. The supported zero-valent iron materials have higher activity and greater flexibility for environmental remediation applications than other forms of ZVI. Nano ZVI supported on micro-scale exfoliated graphite was prepared by using KBH4 as the reducing agent in the H2O/ethanol solution of Fe^2＋ in the laboratory. Then the ethanol solution of Cu^2＋ was added to the fleshly prepared wet supported nano ZVI. The Fe/Cu bimetallic particles supported on the graphite were obtained because of the reduction and deposition of Cu on the Fe surface. The TEM image showed that iron particles were highly dispersed on the surface of graphite. In this study, supported zero valent Cu/Fe bimetallic nanoparticles were used for the dehalogenation of trichloroethylene （TCE） in batch experiments. The dechlorination rate of supported zero valent Fe/Cu bimetallic nanoparticles was greater than the supported nano ZVI. Supported Cu/Fe bimetal with 4 wt% Cu had the fastest dehalogenation rate than that with different content of Cu. When the nana FeO dosage was 5 g/L in the dehalogention system, 8 mg/L of TCE was completely dechlorinated within 4 hours. Increasing or decreasing the FeO dosage, the dechlorination rate could be worse. When the concentration of Fe^2＋ was 0.05 mol/L during the preparation by KBH4 reduction, the nano Cu/Fe particles exhibited the spheral shape with 50-80 nm in size. When the concentration of Fe^2＋ was higher （0.2 mol/L）, the nano particles were the palpus structure and had the poor dehalogenation effect on the TCE.  相似文献   

A simple Newtonian model for the fractal accelerating Universe     

P.?V.?Gruji?Email author 《Astrophysics and Space Science》2005,295(3):363-374

We propose a simple mechanism for driving the recently detected non-decelerating expansion of the observable Universe. It is based on the assumption of the predominance of the vacuum energy over the inert matter and a fractal structuring of the latter. The Newton’s universal gravitational force ensures the attraction between celestial bodies at small and medium astronomical distances, but gives rise to the repulsive interaction between mutually very separated cosmic subsystems, like clusters and superclusters, and thus to the observed accelerating expansion and the fractal structuring.  相似文献