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1.
Ross Gunn 《Journal of The Franklin Institute》1943,236(4):373-390
The deformation of a strong elastic lithosphere supported by an underlying weak magma is calculated for a long mountainous load. The deformations, produce vertical superposed stresses in the lithosphere that contribute to the support of the mountain and distribute its weight over a large area.Employing the principle of isobaric equilibrium, the distribution of the vertical supporting stress and the associated gravity anomalies may be determined by analysis.The results of the analysis are applied to the Hawaiian chain and it is shown that the calculated physical properties and gravity anomalies are remarkably like those observed. It is inferred from the study that: (a) a strong lithosphere underlies the Hawaiians and this section is practically identical with those underlying other regions; (b) the lithosphere will support one-sided stresses approximating 109 dynes/cm.2 for long periods of time; (c) the distribution of gravity anomaly may be described quantitatively in terms of the calculated deformations; (d) the principle of isobaric equilibrium is obeyed throughout the region whereas the isostatic principle is generally violated; and (e) the distribution of compensating masses is not at all like that demanded by the principle of isostasy.It is concluded that isostasy leads to results that are clearly wrong when applied to mountains or other deformed regions. The principle of isobaric equilibrium appears, however, to be well established by the investigation. 相似文献
2.
Ross Gunn 《Journal of The Franklin Institute》1944,237(2):139-154
The principle of isobaric equilibrium is quantitatively applied to a strong lithosphere near a continental boundary. Following methods outlined in earlier papers, the deformation of the lithosphere near Cape Henry is determined from the magnitude and distribution of the sedimentary and fluid load superimposed on the original crystalline basement. From the calculated figure and the equivalent load, the resulting distribution of vertical stress and gravity defect are estimated. Except for the prediction of appreciable positive gravity defects at the continental shelf the calculated and observed gravity distributions are quite similar. The fibre stress due to the deformation is evaluated and it is shown that the position of the calculated maximum stress in tension on the landward side coincides with the observed position of lithospheric failure or the Fall Line. The strength in tension of the upper lithosphere here is shown to be less than 8.5 X 108 dynes/cm2. The simultaneous prediction of the approximate magnitudes of the gravity anomalies, their distribution and the location of the Fall line appears to show that a strong elastic lithosphere characterized by the constant b = 8.4 ± 2 × 10?8 cm?1 has a real and important geological existence.The investigation shows that due to the finite strength of the lithosphere, long linear areas parallel to continental coast lines are usually regions of disturbed gravity. 相似文献
3.
根据Ｈｅｌｌｉｎｇｅｒ－Ｒｅｉｓｓｎｅｒ原理，建立了一种具有一个无外力圆形边界的特殊杂交应力元，其应力场准确满足弹性力学平衡方程、协调方程及无外力圆弧上的边界条件。根据修正的Ｈｅｌｌｉｎｇｅｒ－Ｒｅｉｓｓｎｅｒ原理，建立了另一种具有一个无外力直边界的特殊杂交应力元，其应力场在元上变分满足平衡方程，但准确满足无外力直边上的边界条件。数值算例表明：特殊假定应力元与一般假定位移元这两类元联合，能十分有效地进行纵向倒圆槽孔板的应力集中分析。 相似文献
4.
湿陷性黄土具有遇水发生湿陷、承载力大幅度降低的性质，这种性质直接影响到基础的承载力。本文对湿陷性黄土中的三根支盘桩进行预浸水静载荷试验。结果表明，支盘桩荷载-沉降曲线为缓变型，具有良好的承载性能，荷载传递规律与在非湿陷性黄土地基中具有相似的性质，桩身各段承载力的发挥具有明显的顺序性，本文结果为湿陷性黄土地基中支盘桩的应用提供了比较可靠的依据。 相似文献
5.
论国家信息政策法规的制定原则 总被引：6，自引：0，他引：6
本文阐述了制定国家信息政策法规应该遵循的八个原则：务实性原则、协调性原则、均衡性原则、经济性原则、弹性原则、全面性原则、动态性原则以及重点性原则，对有的制定原则还给出了相应的案例。 相似文献
6.
根据一种修正的余能原理，建立了一类具有一个无外力圆弧边，且结点含转动自由度的4结点杂交应力膜元。该元内假定应力场满足以柱坐标表示的平衡方程，及圆弧边的无外力边界条件；边界位移与相邻元协调。数值算例表明，这类特殊杂交应力元，可有效地分析具有圆形槽孔及倒圆角槽孔板的应力分布。 相似文献
7.
中国大陆热流分布特征及热-构造分区 总被引：16，自引：0，他引：16
根据中国大陆822个实测热流数据,研究了中国大陆主要构造单元的深部地热特征,包括40km深度的地温值、热岩石圈厚度、岩石圈累积强度和有效弹性层厚度(EET)等.结果显示,中国大陆热流的空间分布以及岩石圈热状态和流变学特征均表现出明显的横向非均匀性.这源于太平洋板块俯冲和印度-亚洲碰撞导致的新生代构造热活动.根据热流值和深部地热参数,中国大陆可以划分为东部、中部和西部三个大尺度热-构造区. 相似文献
8.
偶应力问题的非协调元分析 总被引：2，自引：0，他引：2
从偶应力弹性体势能泛函的驻值条件出发,得到了偶应力理论中非协调元体系的能量相容原理。基于其常应力(常偶应力)分片检验条件的强形式,对平面四结点单元的非协调试探内函数进行了优化,提出了一种稳定有效的非协调元方法。有限元列式中,微转动和宏观转动相等的约束条件通过罚因子的形式引入。分析了含中心圆孔的无限平板,在单轴拉伸以及纯剪状态时,偶应力的存在对孔周应力集中的影响。算例表明,该单元计算效率高,精度好,即使在材料本征长度很小时,仍然能够得到相当理想的结果 相似文献
9.
组织内部学习与外部学习作为组织创新的重要知识资源,其在组织创新资源转化进程中发挥着重要作用。但当前关于组织内外部学习间关系（协同效应还是替代效应）及该关系在不同组织结果导向、不同企业发展阶段下是否具有差异化的问题仍然讨论不足。为了识别在不同组织结果导向下内外部学习及其平衡与企业发展阶段的动态匹配规律,研究基于研发企业调研发现：平衡式学习对组织创新绩效具有正向影响,但该学习平衡在不同企业发展阶段呈现出不同的平衡模式。在企业初创期,更宜选择时序性平衡模式;在企业发展期,更宜选择共时性平衡模式;但在企业成熟期,若以组织创新作为学习目标时,两种平衡模式均可,若以组织绩效作为学习目标时,更宜选择时序性平衡模式。研究明确了组织在不同发展阶段如何选择内外部学习平衡模式能为组织带来更佳乃至最佳结果,揭示了不同时期组织内外部学习平衡情境下的组织结果优化策略。 相似文献
10.
《Journal of The Franklin Institute》1987,324(3):369-386
The process of determining the potential energy, as a function of generalized coordinates, of a system consisting of rigid bodies and springs is often extremely laborious. In this paper, a method is presented by means of which all the potential energy terms of a system are calculated in a systematic manner. It is assumed that the system of rigid bodies has a topological tree structure, and that linear springs are situated arbitrarily between the rigid bodies. The method is based on a graph-theoretical approach and is consistent with that of the calculation of kinetic energy presented in (2, J. Franklin Inst., Vol. 324, No. 3, pp. 351–367, 1987). The paper contains the derivation of general formulae for potential energies of gravity and elastic forces. These formulae are implemented for the case of a planar system; an example is also provided. 相似文献
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12.
Charles S. Peskin 《Journal of The Franklin Institute》1974,297(5):335-343
Heart valves when closed consist of membranes under tension bearing a pressure load. Along the lines where the leaflets meet, special support structures under tension are needed (a fibrous ridge for the arterial valves and a network of cords for the atrioventricular valves). The equilibrium of these supports requires that the valve leaflets form cusps along each line of closure. In the aortic and pulmonary valves there is evidence that the stress in the leaflet is borne by a single family of load-bearing fibers covering the surface. Under this hypothesis, we derive a differential equation for the leaflet and show that the fibers are geodetic lines under constant tension. During the large motions of valve opening and closure certain constraints are imposed on the surface metric by the presence of (almost) inextensible fibers in the surface. The severity of the constraints depends on the number of independent families of fibers. 相似文献
13.
采用博弈方法,在构造产学研合作博弈收益表的基础上让不同产学研合作组织选择某种交流方式作为策略,并以收益函数为效用函数对产学研合作组织的不同互动合作网络和不同人员采取不同交流方式的协调进行均衡分析。研究发现:对于任意一个产学研合作互动网络,采取相同交流的策略组合是在纳什均衡的条件下,如果网络是完整的,那么这些是可能仅有的纳什均衡;如果网络不完整,那么可能存在交流方式多样化的均衡。而在每个网络内部参与者采取不同交流的策略组合都是在纳什均衡条件下,无论网络是完整还是不完整的,都可能存在交流方式多样化的均衡。接着分析产学研合作初期阶段中,不同人员交流方式的囚徒困境均衡具有历史路径依赖性,并且难以通过内部协调交流方式走出困境,但是可以通过产学研合作组织中不同人员交流方式的协调达到帕累托均衡。 相似文献
14.
This paper presents a gain-scheduled control approach for the vertical takeoff and landing aircraft. The non-linear aircraft dynamics are formulated as a linear parameter varying (LPV) system with external parameter-dependent disturbance, which arisen from the equilibrating between gravity force and nozzles thrust. The disturbance is dependent on the system varying parameter, roll angle, and a constant parameter denoting the normalized gravity force. The controllers are designed in terms of mixed optimization of H∞ performance for disturbance attenuation and relative stability for tracking position command in pitch-yaw plane. The characteristics of the parameter-dependent disturbance are described by an equality condition with a defined annihilation matrix. By exploring the parameter-dependence condition on disturbance into the controller design algorithms based on linear matrix inequalities (LMIs), it is showed that a better performance can be achieved than simply considering it as an external disturbance. The design results are demonstrated by time response simulations. 相似文献
15.
David J. Teece 《Research Policy》2018,47(8):1367-1387
The value-capture problem for innovators in the digital economy involves some different challenges from those in the industrial economy. It inevitably requires understanding the dynamics of platforms and ecosystems. These challenges are amplified for enabling technologies, which are the central focus of this article. The innovator of an enabling technology has a special business model challenge because the applicability to many downstream verticals forecloses, as a practical matter, ownership of all the relevant complements. Complementary assets (vertical and lateral) in the digital context are no longer just potential value-capture mechanisms (through asset price appreciation or through preventing exposure to monopolistic bottleneck pricing by others); they may well be needed simply for the technology to function. Technological and innovational complementors present both coordination and market design challenges to the innovator that generally lead to market failure in the form of an excess of social over private returns. The low private return leads to socially sub-optimal underinvestment in future R&D that can be addressed to some extent by better strategic decision-making by the innovator and/or by far-sighted policies from government and the judiciary.The default value-capture mechanism for many enabling technologies is the licensing of trade secrets and/or patents. Licensing is shown to be a difficult business model to implement from a value-capture perspective. When injunctions for intellectual property infringement are hard to win, or even to be considered, the incentives for free riding by potential licensees are considerable. Licensing is further complicated if it involves standard essential patents, as both courts and policy makers may fail to understand that development of a standard involves components of both interoperability and technology development. If a technology standard is not treated as the embodiment of significant R&D efforts enabling substantial new downstream economic activity, then rewards are likely to be calibrated too low to support appropriate levels of future innovation. 相似文献
16.
In this research, linear and non-linear stability behaviour of a thin circular FGM plate subjected to the uniform temperature rise and the constant angular velocity loadings is analyzed. Properties of the FGM media are distributed across the thickness based on a power law form. Each property of the metal or ceramic constituents is considered to be the function of temperature based on the Touloukian model. General equilibrium equations for such conditions are obtained based on the classical plate theory. At first, the non-linear governing equations are established in a complete asymmetrical form. After that, two different analytical methods are presented to study the bifurcation behaviour. Existence of bifurcation phenomenon is examined. Pre-buckling analysis is performed for a plate with the immovable clamped edge. Stability equations are obtained based on the adjacent equilibrium criterion. The resulted equations are solved via the two distinct methodologies, i.e. the exact solution in terms of Coulomb wave functions and the power series method. A non-linear solution is also presented to detect the equilibrium path of the heated rotating FGM plate. It is found that the angular speed may stabilize the homogeneous circular plate which buckles during uniform heating. Furthermore, snapping may occur for FGM plates under the simultaneous action of heating and uniform rotation. 相似文献
17.
1991-2011年南海周边国家及地区经济重心及经济发展重心演变分析 总被引：2，自引：0，他引：2
运用重心模型,计算出1991-2011年间南海周边国家及地区经济重心及经济发展重心坐标,揭示南海周边国家及地区经济特征演变过程。研究结果表明:①总体上看,以区域几何中心为参照,经济重心大体呈南北狭长型分布,全部落于区域东北部位置,经济发展重心大体呈团聚状分布,有11个落入东北部,10个落入西北部;②在整体移动轨迹方面,经济重心比经济发展重心表现出更为简洁的特征,2000年后经济重心稳定向西南方向移动,经济发展重心在短时间内会呈现急剧的变化,这说明经济重心存在来自于区域特定方向上的力的强烈作用,而经济发展重心来自于经度和纬度方向上的力都较为均衡;③1999年以后,来自区域西部方向的力持续稳定地拉动经济重心的移动,区域南部的力对经济重心移动极为显著。同时,对经济发展重心而言,1999年后东西方向上的力对其移动作用不显著,在南北方向上有悄然北移的态势;④从区域经济总量和经济发展水平均衡性来看,经济重心在总体上趋于稳定态势,经济发展重心的不均衡性逐渐加强并稳定,且来自于南北方向上的力是造成这种结果的主要原因。 相似文献
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根据杂交应力理性模式，基于一种修正的Hellinger－Reissuer原理，建立了具有一个无外力斜边的杂交应力元，其应力场由无边界面力在非协调位移上所作虚功之和为零的约束条件导出，将这种特殊元与具有一个无外力圆弧边的杂交应力元联合，可有效地分析具有倒圆角V型槽孔板的应力集中，并可提供远较一般假定位移及一般假定应力元准确的孔边应力分布。 相似文献
20.
文章分析了目前应用较广的几种弹性筒夹或弹性胀套结构形式及其优缺点,在此基础上提出一种特殊的弹性胀套,应用于大尺寸工件制造加工的工装夹具或检测圆周形位公差的量检具等场合。为确保设计合理、使用可靠,利用Solidworks的内嵌分析软件CosMosworks系统进行有限元接触分析,避免胀套弹性不足或产生塑性变形,以确定最优的结构形式。并以汽车制动器总成的摩擦片全跳动检具为例,阐述弹性胀套在检具上的应用,解决了其他类型胀套不易解决的问题,具有广泛的推广价值。 相似文献