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961.
旋转水射流破岩钻孔机理研究 总被引:2,自引:0,他引:2
基于水射流破岩钻孔过程中影响因素和流固耦合作用的分析,运用连续损伤力学和细观损伤力学理论,建立了适用于水射流破岩全过程的岩石损伤模型。依据所建立的损伤模型,利用非线性动力有限元方法,对旋转水射流破岩钻孔过程的过程进行了模拟,其中岩石损伤场的求解采用解耦的方法。计算结果与试验一致,表明旋转射流具有较强的破岩能力,其原因是旋转射流的质点具有三维速度,破岩时以倾斜冲击为主,易于在岩石表面形成拉伸和剪切破坏,回流的干扰较少。破岩过程首先是形成一环形破碎带,然后沿径向和轴向发展,所形成的破碎坑呈内凸锥状。旋转射流破岩的优势在于破碎面积大、效率高、破岩比能低,因而旋转水射流能够钻出大直径的岩石孔眼。 相似文献
962.
M. Zhou D. Shu K. Li W. Y. Zhang H. J. Ni B. D. Sun J. Wang 《Metallurgical and Materials Transactions A》2003,34(5):1183-1191
The inclusions in molten aluminum were removed using the deep filtration of ceramic foam filters and ceramic particles with
active coatings. The results of tensile tests showed that the elongation of the filtered tensile specimen S6 increases by 17.93 pct, but the tensile strength does not. The scanning electron microscope (SEM) examination showed that
the secondary cracks and dimples in the filtered tensile specimen S6 were finer and more homogeneous than those in the unfiltered tensile specimen S0. In addition, metallographic examination showed that there were only a few inclusions of approximately 6 μm in diameter in the filtered specimen S6, but more inclusions of approximately 40 μm in diameter were found in the unfiltered specimen S0. The filtration efficiency of the coated ceramic particles was higher than that of the coated ceramic foam filters. The active
coating could effectively capture the inclusions and dissolve Al2O3 in them during filtration. 相似文献
963.
964.
添加剂及其对镍电极的作用机理 总被引:6,自引:0,他引:6
本文综述了添加剂对镍电极的活性物质利用率、放电电位、使用寿命和宽温度范围内使用性能的影响及其作用机理。总结归纳了α-Ni(OH)_2的制备与稳定性机理、物理与化学性能、以及α-Ni(OH)_2/γ-NiOOH作为镍电极活性物质的可行性。最后还简述了添加剂的载入方式。 相似文献
965.
V M Rashkovan N A Khizhnyak A V Basteev L A Bazyma Luis Ni?o de Rivera I A Ponomaryova 《The Journal of microwave power and electromagnetic energy》2003,38(4):225-235
The basic correlation is defined which characterizes an influence of electromagnetic radiation on a system of individual particles of ellipsoidal geometry dispersed into some volume (chaotic arrangement) of another medium. The field intensity inside one isolated particle is determined depending on the parameters of the external (relative to the volume) electromagnetic field. Energy loss in an isolated particle is calculated. The shielding effect of a field in an isolated particle by other surrounding particles is taken into account. The relative dielectric permittivity and the relative loss tangent as a function of grain moisture content are measured. Drying and disinfestation of wheat grain by electromagnetic methods are observed. 相似文献
966.
967.
Data dependence uniformization, a method for overcoming the difficulties in parallelizing a doubly nested loop with irregular dependence constraints is proposed. This approach is based on the concept of vector decomposition. A simple set of basic dependences is developed from which all dependence constraints can be composed. The set of basic dependences is added to every iteration to replace all original dependences so that the dependence constraints become uniform. An efficient synchronization method is presented to obey the uniform dependence constraints in every iteration 相似文献
968.
水压爆破是一种控制爆破技术,它可在不动用机械设备情况下,用水作为介质,把炸药的爆炸能传递给待拆构筑物,达到破碎的目的。本文介绍采用水压爆破拆除钢筋混凝土工事的设计与实施,爆破取得圆满成功。 相似文献
969.
在考虑爆轰波与孔壁相互作用及孔壁的可压缩性等主要因素情况下,根据爆轰理论和流体动力学原理,建立了计算偶合装药点起爆时孔壁动态初始参量的物理模型,给出了计算公式。计算了中等威力炸药(如2#岩石炸药、乳化炸药和水胶炸药)在混凝土中爆炸时孔壁动态初始参量(如初始冲击波压力、速度等值),得到了自起爆点开始沿炮孔长度方向各参量的变化规律、并得出了一些有意义的结论。 相似文献
970.
PURPOSE: Surgery and systemic chemotherapy offer modest benefit to patients with recurrent glioblastoma multiforme. These tumors are associated with rapid growth and progressive neurological deterioration. Radiosurgery offers a rational alternative treatment, delivering intensive local therapy. A pilot protocol to treat recurrent glioblastoma was developed using fractionated stereotactic radiosurgery with concurrent intravenous (i.v.) Taxol as a radiation sensitizer. METHODS AND MATERIALS: The treatment outcome was analyzed in 14 patients with recurrent glioblastoma treated with fractionated stereotactic radiosurgery and concurrent Taxol. Median tumor volume was 15.7 cc and patients received a mean radiation dose of 6.2 Gy at 90% isodose line, 4 times weekly. The median dose of Taxol was 120 mg/m2. RESULTS: The median survival was 14.2 months, 1-year survival was 50%. CONCLUSIONS: Survival for this small group of patients was similar to or better than historical controls or patients treated with single-fraction radiosurgery alone. This data should stimulate the investigation of both fractionated radiosurgery and the development of radiation sensitizers to further enhance treatment. 相似文献