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1.
《Acta Metallurgica》1979,27(6):1075-1084
The problem of the stability of an array of elastically interacting plate-shaped precipitates is considered. Algebraic conditions for stability against coarsening are developed, and the results of detailed numerical tests of the stability against displacement and of the stability against coarsening, of a particularly simple and symmetric array are reported.  相似文献   

2.
This study investigated whether longitudinal predictions of stability are improved when assessments of the relationship are obtained from both members of the couple rather than just from 1 partner and, if so, which partner's assessments are the most diagnostic of stability. Both partners in 120 dating couples provided self-report assessments on 16 relationship dimensions, and 6 months later 2 outcomes were examined: stability and emotional distress if breakup had occurred. Assessments from both partners were more predictive of stability than were assessments from 1 (randomly chosen) partner, but the improvement was small. Assessments from female partners were no more predictive of stability than were those from male partners. However, assessments from "weak-link" partners (whose standing on stability indicators was lower than the other member of the couple) were significantly more diagnostic of stability than were those from "strong-link" partners. These and other findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

3.
采空区是地下矿山重大安全隐患源,其稳定性是行业科技工作者关注的焦点.以石英脉型钨矿山采空区稳定性评价作为研究对象,基于未确知测度计算理论,构建了适用于脉型矿床的采空区危险性评价体系及分级标准,并应用于矿山评价实践.结果表明:浅孔留矿法单脉开采空区稳定性普遍优于阶段矿房法脉带开采空区,矿柱的回收极大地加速了空区的失稳破坏...  相似文献   

4.
L Sennerby  N Meredith 《Canadian Metallurgical Quarterly》1998,19(5):493-8, 500, 502; quiz 504
Achievement and maintenance of implant stability are prerequisites for long-term positive outcomes for osseointegrated implants. Thus, implant stability is the key to clinical success. Until recently, it was not possible for the clinician to predictably distinguish implants with different degrees of stability. Because there seems to be a correlation between implant failure and bone properties, it is possible that clinically firms implants with poor stability are more prone to failure than more stable implants. This article discusses the development and possible future use of a novel technique for clinical measurement of implant stability and osseointegration--resonance frequency analysis.  相似文献   

5.
生态护坡法在国内外得到了广泛的应用与发展.通过回顾前人在生态边坡稳定性方面各类模型试验研究,从导致边坡失稳的重力作用因素、冲刷作用因素、水的入渗侵蚀作用因素、风蚀作用因素以及地震或其他形式等作用因素进行分类展开,介绍了目前生态边坡稳定性模型试验的研究现状,对比评述了各生态护坡稳定性模型试验研究中所取得的成果以及各类模型试验方案的可取之处,同时也提出了生态护坡稳定性模型研究中所存在的一些不足之处,并对生态护坡研究的未来发展趋势进行了展望.   相似文献   

6.
赵庆和 《云南冶金》1999,28(4):7-10,19
脞影响顶板稳定性的基本因素,评价指标出发,根据大姚顶板岩体的参数和实际盘区顶板稳定性的分析,优选和论证了大姚盘区的结构参数,其分析方法对顶板稳定性评价,有一定参考价值。  相似文献   

7.
本文讨论了一类变时滞中立系统的时滞依赖渐近稳定性问题.通过利用Lyapunov-Krasovskii泛函(LKF)和自由权矩阵方法,得到了该系统渐近稳定性的时滞依赖新判据.交叉项间的联系由Leibniz-Newton公式给出.定理的推导没有利用模型转换和交叉项有界方法.由于结果以严格线性矩阵不等式形式给出,所以很容易验证所考虑系统的稳定性.最后的数值实例验证所给判据的有效性和对已有结果的改进.  相似文献   

8.
Cross frames and diaphragms are critical elements for the stability of I-shaped steel bridge girders during construction. The AASHTO specifications are relatively vague with regards to the stability design requirements of the braces. Spacing limits that have been used in past AASHTO specifications have been removed from the Load and Resistance Factor Design Specification, which instead requires the bracing to be designed by a rational analysis. Whereas the AASHTO specification does not define what constitutes a rational analysis, stability bracing systems must possess adequate stiffness and strength. The commercially available software packages that are typically used in bridge design generally do not have the capabilities to determine the adequacy of the bracing from a stability perspective. This paper outlines the stability bracing requirements for bridges with normal and skewed supports. The effects of support skew on the stiffness and strength requirements for stability bracing are addressed. Solutions that are available for systems with normal supports were modified to account for the effects of the support skew angle. Two orientations of the intermediate bracing were considered: parallel to the skew angles and perpendicular to the longitudinal girder axis. The solutions are presented and compared with finite-element results. The design solutions have good agreement with the finite-element solutions.  相似文献   

9.
对于复杂采空区的现状,采空区处理是亟待解决的问题.在选择充填和封闭联合处理采空区的前提下,通过使用关系矩阵与模糊数学联合的采空区稳定性分析方法,得到了各采空区的稳定性系数,结合采空区稳定性系数及地压监测结果,进行了采空区处理方案的模糊推理系统研究,通过研究能得到与每个采空区相适应的处理方法,为矿山的地压处理提供了相应的理论依据,并为矿山的安全生产提供了保障,同时也对类似采空区处理提供了一定的依据.  相似文献   

10.
李茂 《山东冶金》2012,(4):10-12
界面稳定性是金属定向凝固过程中一个很重要的问题,关于它的研究也层出不穷。综述了这一领域的主要进展,着重讨论了基于MS理论研究的各种界面稳定性理论,并指出电磁场对界面稳定性的影响,同时分析了需进一步研究的主要方向。  相似文献   

11.
A finite-element approach is used to analyze the slope stability problem and to examine the effect of soil dilatancy on the stability of slopes. It is found that soil dilatancy has a significant effect on the stability of slopes, and that higher values of dilation angle lead to larger stability numbers. Therefore, the stability numbers obtained from limit analyses (lower∕upper bound solutions) are not conservative for granular soils that exhibit a dilation angle smaller than a soil's friction angle.  相似文献   

12.
13.
姚高辉  吴爱祥  王贻明 《黄金》2009,30(12):25-28
通过对白牛厂矿区的工程地质调查、矿岩力学性质试验,选取了表征矿山岩体工程质量的各种指标,获得了岩体工程分类结果——RMR值和Q值,并根据评分结果分别对井下采场安全,跨度和采空区稳定时间进行了评价和预测。应用Mathews稳定图法中稳定数的计算方法,计算出各类岩石的稳定数,然后根据拟合的稳定数与形状因子间的函数关系,得到各类围岩采空区破坏时形状因子,以此计算出了采空区围岩发生破坏时的采场暴露面积。最后,针对矿山井下无支护或支护失效的现状,提出了相关解决方案。  相似文献   

14.
The ability to assess channel stability of gravel bed rivers in the vicinity of structures such as bridges, culverts, and roadways is necessary for bridge inspection, design, and the mitigation and prediction of erosion at those structures. Given the time constraints for bridge inspections and the expense of conducting lengthy geomorphic studies, it is desirable to have a technique for rapid assessment. Although several methods are currently available for the rapid and qualitative assessment of stability, these methods are often vague or apply only to a specific region. In this paper, we review existing methods and parameters for assessing channel stability and develop a systematic rapid channel stability assessment method based on various aspects of the existing methods. The rapid assessment method provided here is based on 13 qualitative and quantitative indicators of morphologic processes. The indicators are rated, weighted, and summed to produce a stability rating for gravel bed channels. The method is demonstrated through application to several streams in Pennsylvania and Maryland.  相似文献   

15.
辊系是六辊可逆冷轧机的核心部分,其稳定性对带钢质量的影响至关重要。影响六辊可逆冷轧机稳定性的因素有很多,因此在设计时,通常会将设置一个偏移量e,使辊系在轧制过程中承受一定的侧推力,进而保证辊系的稳定性。本文主要针对该点对六辊可逆冷轧机辊系的受力情况进行了较详细的分析,并得出了保证辊系稳定性的条件。  相似文献   

16.
Stability Charts for the Collapse of Residual Soil in Karst   总被引:1,自引:0,他引:1  
Collapse of the residual soil over bedrock cavities often occurs during construction in karst terrain, particularly when the thickness of the residuum is reduced during excavation. Even if an estimate of the strength of the residual soil is known, uncertainty with respect to the size/geometry of the subterranean voids makes a detailed analysis difficult, and straightforward methods to check the stability are needed. In this study, numerical analyses were performed to develop a stability chart expressed in terms of a dimensionless stability number and the geometry of a potential void in the residual soil. The stability charts include the effect of friction angle, and are also developed to allow the investigation of the effect of the inverted strength profile typically observed in karst terrain. Such stability numbers may be useful to estimate the stability of a given site based on the expected thickness of the soil overburden and the likely range of anticipated soil void diameters.  相似文献   

17.
Unlike previous mechanical actuator loading methods, in this study, a hydrodynamic loading method was employed in a flow flume for simulating ocean currents induced submarine pipeline stability on a sandy seabed. It has been observed that, in the process of pipeline losing lateral stability in currents, there usually exist three characteristic times: (1) onset of sand scour; (2) slight lateral displacement of pipeline; and (3) breakout of pipeline. An empirical linear relationship is established between the dimensionless submerged weight of pipeline and Froude number for describing pipeline lateral stability in currents, in which the current-pipe-soil coupling effects are reflected. Scale effects are examined with the method of “modeling of models,” and the sand particle size effects on pipeline stability are also discussed. Moreover, the pipeline stability in currents is compared with that in waves, which indicates that the pipeline laid directly upon the sandy seabed is more laterally stable in currents than in waves.  相似文献   

18.
讨论Hilbert空间上半线性随机发展方程dY(t)=[AY(t)+f(Y(t))dt+G(Y(t))]dw(t)的稳定性。为此引进了适度解的正则性和常返性等概念,利用Liapunov直接法得到了此类随机发展方程的随机渐近稳定性、随机指教稳定性、p-稳定性和几乎必然指数稳定性的充分性判据。这些结果不但推广了有限维情形的工作,同时也发展了A.Ichikawa的工作。  相似文献   

19.
某金矿尾矿库加高扩容的可行性研究   总被引:1,自引:0,他引:1  
文章通过对尾矿库加高扩容采用细颗粒向上堆坝,需要进行的主、副坝体现状的稳定计算复核,分析了影响尾矿库稳定性的几个因素,包括坝体边坡、尾矿粒度、尾矿库的放矿工艺、坝体内尾矿水的渗出与否、尾矿的渗透固结,提出了治理措施,保证现状坝体稳定的基础上进一步论证了尾矿库加高扩容的可行性.  相似文献   

20.
Critics have argued that personality factors believed to represent a vulnerability to depression are not stable and are therefore state dependent. However, conclusions regarding the stability of personality and the relation between personality and depression have been drawn (a) without differentiating relative stability among individual differences from absolute stability of change scores and (b) without explicitly modeling change in personality as a function of change in depression. The relation between neuroticism and depression was examined in a sample of depressed outpatients (N = 71) receiving a 5-week trial of pharmacotherapy. Measures of neuroticism and extraversion demonstrated both relative stability and absolute change, and changes in neuroticism and extraversion scores were modestly or not at all accounted for by changes in depression scores. Claims that personality scores are not stable and are state dependent must be reconsidered.  相似文献   

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