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991.
条形药包爆破破岩规律的试验研究   总被引:3,自引:1,他引:3  
杨年华 《工程爆破》1995,1(1):20-25
分析了前人关于爆破破岩机理论述方面的矛盾,通过高速摄影观察有机玻璃中条形袋药爆炸波和破裂缝发展规律,得到了关于条形药包爆破破岩规律方面的新认识。提出了冲击该、气体膨胀压和反射拉伸波在破岩过程中各自所起的不同作用。特别在此基础上推出了条形药包下破裂深度计算公式,对工程实践有积极的指导作用。  相似文献   
992.
轮胎的动态特性是影响包括操纵稳定性、行驶平顺性在内的车辆整体性能的重要指标之一。建立了考虑轮胎的实际边界条件、复杂材料特性的有限元模型,进行了考虑非线性大变形的模态分析。同时分析了影响模态频率的各个因素,主要包括轮胎胎压、轮胎侧壁材料和轮胎胎体质量。  相似文献   
993.
介绍几种新近开发的针对PAN基原丝、预氧丝和炭丝微结构和结构缺陷的X射线衍射与散射定量表征技术,它们是:纤维材料中柱状(椭球状)纳米取向微孔体积分数X射线小角散射定量表征方法;纤维材料中柱状(椭球状)纳米取向微孔取向角的小角散射定量表征方法;预氧丝中链状相与环化相体积分数的小角衍射定量表征方法以及炭纤维中乱层石墨相与单层石墨相的X射线广角衍射定量表征方法等。  相似文献   
994.
A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented.The breadth(or depth) first search spanning tree can be obtained based on an adjacency matrix of the mechanism.Then the kinematic chain(or mechanism)’s basic loops can be obtained.On the basis of these basic loops,a mathematical model of kinematic analysis can be established and solved automatically.In the sense of a calculative mechanism,structural analysis of the kinematic chain relates to the kinematic analysis of a mechanism.Thus,an effective way is supplied to the given mechanism’s kinematic analysis for automatic modeling and solving,and a method is supplied to the structural type to optimize kinematic synthesis.  相似文献   
995.
996.
The method of fundamental solutions is applied to the computation of stress intensity factors in linear elastic fracture mechanics. The displacements are approximated by linear combinations of the fundamental solutions of the Cauchy–Navier equations of elasticity and the leading terms for the displacement near the crack tip. Two algorithms are developed, one using a single domain and one using domain decomposition. Numerical results are given. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
997.
Havelock’s type of expansion theorems, for an integrable function having a single discontinuity point in the domain where it is defined, are utilized to derive analytical solutions for the radiation or scattering of oblique water waves by a fully extended porous barrier in both the cases of finite and infinite depths of water in two-layer fluid with constant densities. Also, complete analytical solutions are obtained for the boundary-value problems dealing with the generation or scattering of axi-symmetric water waves by a system of permeable and impermeable co-axial cylinders. Various results concerning the generation and reflection of the axisymmetric surface or interfacial waves are derived in terms of Bessel functions. The resonance conditions within the trapped region are obtained in various cases. Further, expansions for multipole-line-source oblique-wave potentials are derived for both the cases of finite and infinite depth depending on the existence of the source point in a two-layered fluid.  相似文献   
998.
A dynamic mutation in exon 1 of the FMR1 gene causes Fragile X-related Disorders (FXDs), due to the expansion of an unstable CGG repeat sequence. Based on the CGG sequence size, two types of FMR1 alleles are possible: “premutation” (PM, with 56-200 CGGs) and “full mutation” (FM, with >200 triplets). Premutated females are at risk of transmitting a FM allele that, when methylated, epigenetically silences FMR1 and causes Fragile X syndrome (FXS), a very common form of inherited intellectual disability (ID). Expansions events of the CGG sequence are predominant over contractions and are responsible for meiotic and mitotic instability. The CGG repeat usually includes one or more AGG interspersed triplets that influence allele stability and the risk of transmitting FM to children through maternal meiosis. A unique mechanism responsible for repeat instability has not been identified, but several processes are under investigations using cellular and animal models. The formation of unusual secondary DNA structures at the expanded repeats are likely to occur and contribute to the CGG expansion. This review will focus on the current knowledge about CGG repeat instability addressing the CGG sequence expands.  相似文献   
999.
Matrix metalloproteinases are a family of enzymes fundamental in inflammatory processes. Between them, MMP-9 is up-regulated during inflammation; thus, its quantification in non-invasive fluids is a promising approach for inflammation identification. To this goal, a biomarker quantification test was developed for ocular inflammation detection using anti-MMP-9 antibody microarrays (AbMAs). After validation with eight healthy control tear samples characterized by ELISA, 20 samples were tested from individuals diagnosed with ocular inflammation due to: cataracts, glaucoma, meibomian gland dysfunction, allergy, or dry eye. Concentration values of tear MMP-9 were obtained for each sample, and 12 patients surpassed the pathological threshold (30 ng/mL). A significant elevation of MMP-9 concentration in the tears of glaucoma patients compared with healthy controls was observed. In order to evaluate the diagnostic ability, an ROC curve analysis was performed using our data, determining the optimal threshold for the test at 33.6 ng/mL of tear MMP-9. In addition, a confusion matrix was applied, estimating sensitivity at 60%, specificity at 88%, and accuracy at 68%. In conclusion, we demonstrated that the AbMAs system allows the quantification of MMP-9 in pathologies that involve inflammation of the ocular surface.  相似文献   
1000.
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