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从一个常见的不等式谈起,分析了多种证明方法,运用该不等式推导出了多个重要结论,对不等式进行了扩充和加强,解释了蕴含的意义,显示了该不等式的重要性和深刻性. 相似文献
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基于粗糙集的患者满意度评价模型及其实证分析 总被引:1,自引:0,他引:1
在文献阅读及实地调研的基础上,本文提出了患者满意度的定义,建立了影响患者满意度的指标体系,介绍了粗糙集的相关概念及利用粗糙集进行评价的步骤,提出了新的约简方法,构建了基于粗糙集的患者满意度评价模型并进行了实证分析,得出了影响患者满意度的关键指标,并计算了关键指标权重,对江西省十个医院进行了综合评价值的计算. 相似文献
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提出了交通运输系统协调度的评价分析模型.从系统论的观点出发,提出了交通运输系统协调理论的概念,探讨了交通运输系统随时间而不断演化变迁的规律,给出了交通运输系统协调发展基本步骤;并根据协调学原理,讨论了交通运输系统的协调性问题,提出了系统协调发展模型,对交通运输子系统内部及子系统之间及系统整体的协调发展问题进行了研究,探讨了交通运输可持续发展的系统协调管理过程,为进一步研究交通运输系统的可持续发展奠定了基础. 相似文献
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分层教学的Bayes分析 总被引:3,自引:0,他引:3
对学校分层教学进行了初步探索 ,提出了分层分班的 Bayes决策 ,介绍了分层分班方法 ,获得了一些结论 ,并完成了对这些结论的证明 ,从理论上论述了分层教学是实施“因材施教”教育原则和素质教育的有效途径 ,给出了应用实例 . 相似文献
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概述了干扰管理理论的内涵、意义以及目标,依据未来不确定因素引起飞机备件需求量变化以及备件供应时限性增强的实际情况,创建了时限一致度算子,优化了备件需求泊松分布模型,提高了备件供应的精确度,并选取了优化后的模型中的多个参量,进行了多因素的扰动性分析,最后构造了算例,验证了本方法的科学性和有效性. 相似文献
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研究了大型汽轮发电机定子端部固定绕组的压板松动时,位于两侧压板间某段绕组的振动问题.首先,采用分离变量法,给出了发电机运行时定子端部绕组区域的磁感应强度表达式,并给出了绕组所受电磁力及与松动压板间摩擦力的计算式.其次,建立了研究绕组非线性振动问题的力学分析模型,采用多尺度法对主共振情形进行了解析求解,推得了稳态运动下的幅频响应方程,并对定常解的稳定性及分岔奇异性进行了研究,得到了稳定性的判定条件及分岔方程的转迁集.最后,针对工程实际问题进行了计算,给出了相应的幅频响应曲线图,并进行了分析讨论. 相似文献
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颤振分析中判断颤振临界速度的重要依据是系统V-g和V-f图,即系统特征值随参数的变化曲线.在几乎所有商用软件及自编程序的输出结果中,有时会出现所谓的"窜支"现象,这给颤振临界速度和颤振穿越分支及耦合形式的判断带来很大不便.通过隐函数定理可以证明,除重特征值点以外,系统特征值连续依赖于系统参数变化.依据多元向量值函数连续性,建立对特征值的排列算法,给出系统特征根轨迹的正确曲线,再输出V-g和V-f图数据,从而避免"窜支"现象.编制应用程序,通过几个典型算例对算法进行了验证.该工作能够有效简化颤振分析的后处理工作,提高分析效率. 相似文献
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Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep
under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the
experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological
creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the
stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation
and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem
confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between
the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction
in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference
in their porosity.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.)
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000. 相似文献
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V. P. Stavrov V. V. Stavrov N. V. Pankova K. Friedrich 《Mechanics of Composite Materials》2000,36(2):155-162
The influence of displacements of tensioned fibers on the impregnation of fibrous layers with a polymer melt and on the final
composite structure is studied. Using computer simulation, it is shown that, during impregnation, the structure of tensioned
fibrous layers changes considerably depending on the initial arrangement and tensioning of fibers. The consolidated regions
formed under the melt front move inside the impregnated layer with the advancing melt front. Displacement of the tensioned
fibers as well as the formation of “washouts” favors the impregnation of internal layers, but cause significant inhomogeneity
of the polymer structure. The surface (on the side of the melt flow) regions are more saturated with the polymer than the
internal ones. A difference in the melt percolation mechanisms at various impregnation regimes is revealed. The effective
permeability coefficients of a tensioned fiber layer are not constant but depend on the conditions and regimes of impregnation.
Submitted to the 11th Conference on the Mechanics of Composite Materials (Riga, June 11–15, 2000).
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 259–270, March–April, 2000. 相似文献
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The shear failure of reinforced concrete beams needs more attention than the bending failure since no or only small warning
precedes the failure. For this reason, it is of utmost importance to understand the shear bearing capacity and also to be
able to undertake significant rehabilitation work if necessary. In this paper, a design model for the shear strengthening
of concrete beams by using fiber-reinforced polymers (FRP) is presented, and the limitations of the truss model analogy are
highlighted. The fracture mechanics approach is used in analyzing the bond behavior between the FRP composites and concrete.
The fracture energy of concrete and the axial rigidity of the FRP are considered to be the most important parameters. The
effective strain in the FRP when the debonding occurs is determined. The limitations of the anchorage length over the cross
section are analyzed. A simple iterative design method for the shear debonding is finally proposed.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 3, pp. 357–372, May–June, 2008. 相似文献
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Evald Übi 《Central European Journal of Mathematics》2005,3(2):228-241
A linear programming problem is transformed to the finding an element of polyhedron with the minimal norm. According to A.
Cline [6], the problem is equivalent to the least squares problem on positive ortant. An orthogonal method for solving the
problem is used. This method was presented earlier by the author and it is based on the highly developed least squares technique.
First of all, the method is meant for solving unstable and degenerate problems. A new version of the artifical basis method
(M-method) is presented. Also, the solving of linear inequality systems is considered. 相似文献
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Using the most comprehensive data set now available, this investigation tests the precision of all exchange theories that now contend. Beyond precision, the investigation focuses on broad issues of effectiveness including consistency, parsimony, and whether the theories can be applied to structures larger than normally studied in the lab. Seeking greater parsimony, this investigation introduces a new model by combining parts of two contending theories. We find that all ten theories have scientific merit for all can predict with some effectiveness for the exchange structures experimentally investigated. Nevertheless, the ten vary in precision. Elementary Theory is the most precise. The new Expected-value Resistance model ranks second in precision and is the simplest. Both apply to large networks as well as the best of the other theories. 相似文献
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The nonlinear response of an oscillatory bubble in a complex fluid is studied. The bubble is immersed in a Newtonian liquid, which may have a dilute volume fraction of anisotropic additives such as fibers or few ppm of macromolecules. The constitutive equation for the fluid is based on a Maxwell model with an extensional viscosity for the viscous contribution. The model is considered new in the study of bubble dynamics in complex fluids. The numerical computation solves a system of three first order ordinary differential equations, including the one associated with the solution of the convolution integral, using a fifth order Runge–Kutta scheme with appropriated time steps. Asymptotic solutions of governing equation are developed for small values of the pressure forcing amplitude and for small values of the elastic parameter. A study of the bubble collapse radius is also presented. We compare the results predicted by our model with other model in the literature and a good agreement is observed. The calculated asymptotic solutions are also used to test the results of the numerical simulations. In addition, the orientation of the additives is considered. The angular probability density function is assumed to be a normal distribution. The results show that the model based on the fully aligned additives with the radial direction overestimates the tendency of the additives to stabilize the bubble motion, since the effect of extensional viscosity occurs due to the particle resistance to the movement throughout its longitudinal direction. 相似文献
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区块链是新一代信息技术的重要组成部分,是分布式网络、加密技术、智能合约等多种技术集成的新型数据库软件。过去的十多年,区块链技术在全球范围内产生广泛影响。如今的区块链技术,已从最初的关注于解决货币和支付的去中心化问题,转入到解决市场的去中心化问题。智能合约的出现使得基于区块链技术的去中心化金融进入高速发展状态,也涌现出区块链环境下的各类拍卖场景。本文首次从机制设计角度,以区块链交易费机制,非同质化代币(Non-Fungible Token,NFT)拍卖和矿工可提取价值(Miner-Extractable Value,MEV)交易位置拍卖为主要对象,总结和剖析近些年来区块链上特有的拍卖机制;并针对区块链特性,提出区块链上拍卖机制设计所面临的挑战和未来亟待解决的问题。 相似文献
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K. Petras 《Constructive Approximation》1998,14(2):231-245
We consider error estimates for optimal and Gaussian quadrature formulas if the integrand is analytic and bounded in a certain
complex region. First, a simple technique for the derivation of lower bounds for the optimal error constants is presented.
This method is applied to Szeg?-type weight functions and ellipses as regions of analyticity. In this situation, the error
constants for the Gaussian formulas are close to the obtained lower bounds, which proves the quality of the Gaussian formulas
and also of the lower bounds. In the sequel, different regions of analyticity are investigated. It turns out that almost exclusively
for ellipses, the Gaussian formulas are near-optimal. For classes of simply connected regions of analyticity, which are additionally
symmetric to the real axis, the asymptotic of the worst ratio between the error constants of the Gaussian formulas and the
optimal error constants is calculated. As a by-product, we prove explicit lower bounds for the Christoffel-function for the
constant weight function and arguments outside the interval of integration.
September 7, 1995. Date revised: October 25, 1996. 相似文献