共查询到20条相似文献，搜索用时 250 毫秒
1.
《数学学习与研究(教研版)》2010,(6):29-32,39
一个点如果在某函数的图像上,那么这个点的坐标满足函数的解析式,即把点的坐标代入解析式中,解析式左右两边相等．反之,一个点不在函数的图像上,这点的坐标不满足函数的解析式,利用这个关系,当知道一个点的横坐标时,可以求出它的纵坐标,知道一个点的纵坐标时,可以求出它的横坐标,这些都是在解题中最常用的方法． 相似文献
2.
目的:旋转机械由于工作环境复杂,在运行过程中会不可避免地受到各种不确定性因素的影响,从而引发转子系统的异常振动。因此,迫切需要对系统工作状态开展可靠性分析。本文将外部扰动不确定性与模型不确定性考虑在内,旨在建立转子系统运行状态的可靠性评估指标,丰富转子动力学理论体系,为工程应用提供参考。创新点:1.采用非参数法进行建模,能够将外部扰动不确定性与模型不确定性同时包含在内;2.在非参数建模基础上,结合响应谱分析法进行可靠性计算,可避免对系统先验知识的需求并降低计算过程的复杂性;3.将短周期预测理论扩展应用于可靠性分析验证。方法:1.借助非参数法建立转子系统的随机不确定性模型;2.结合响应谱分析法推导出系统可靠性指标计算式;3.采用短周期预测方法对模拟数据统计指标进行计算与验证。结论:1.本方法可用于评估大型复杂旋转机械系统的可靠性,尤其对于服役时间较长导致系统参数出现不确定性变化的情形;2.本研究结果可为大型复杂旋转机械的设计、运行和控制提供理论基础,同时也可以为其他类型机械设备的可靠性分析和预测方法提供参考。 相似文献
3.
首先介绍了一种线路坐标计算的通用数学模型,之后用Visual C 6.0设计、实现基于该模型的线路坐标计算软件.应用结果表明,该软件可以解算基本型、S型、卵型、凸型、复合型、C型等诸多复杂线形的任意指定点的坐标,解算结果准确可靠. 相似文献
4.
运用可靠性理论与最优化设计技术，提出了机械零部件的可靠性优化设计方法，建立了可靠性优化设计数学模型。文中以某内燃机气门弹簧设计为例，在满足可靠度约束及结构几何约束的条件下，以体积最小作为优化目标函数进行可靠性优化设计，得到了比常规设计更为合理的设计结果。实例证明该方法在机械零部件的设计中是可行的，具有实用价值。 相似文献
5.
根据概率可靠性设计原理,给出了高压油气管道可靠度计算的公式.并使用该方法对某高压油气管道进行了可靠度计算.结果表明：该方法对高压油气管道的设计具有一定的指导意义. 相似文献
6.
提出了一种基于Leap Motion识别手势控制机械臂的方法.该方法首先使用Leap Motion对人体手部深度点云信息进行提取,获得手部位姿态、手指位姿以及手势识别.然后将手部各关节点的空间姿态坐标转换为机械臂每个关节的控制角度.最后通过串口与下位机Arduino进行信息交互,实现机械臂向前、左右、抓取等动作.实验表明,该方法可以准确识别人体手势,实时控制机械臂. 相似文献
7.
在随着2000国家大地坐标系在全国不断推广与应用,将ITRF2000框架下的坐标转换到CGCS2000框架时,需先转换到ITRF1997框架下。采用布尔沙——沃尔夫模型对基于不同基准的两框架之间进行坐标转换,设计七参数求解程序,并通过实例分析验证其准确性和可靠性。 相似文献
8.
数学是科技的基础,也是农业和机械专业的一门重要基础课程,本文从合肥手扶拖拉机厂的两个机械零件加工、切割计算和设计过程中所需的点的位置的确定及有关计算的实例,联系解析几何学科中求点的坐标及有关计算,来具体说明数学在解决各种实际问题中的广泛应用。 相似文献
9.
李冲 《辽宁科技学院学报》2011,13(4):32-34
以改造测量控制网灵敏度优化设计为理论基础,对某一三角网的部分网形进行了改造灵敏度的优化设计。在设计中采用了在原网中加测一部分边长,以降低网形的整体灵敏度来改善原控制网的质量。采用改造控制网灵敏度的优化设计方法,可以获得一种测量工作量最小,经济指标最高的改造方案,并能提高原有测量控制网的精度。 相似文献
10.
刀具的几何角度及其对切削性能的影响一直以来都是机械加工工艺教学的重点和难点.笔者结合长期教学和实践,利用VC＋＋进行刀具参数化设计.该设计作为计算机辅助教学课件应用到机械加工工艺教学中可以收到良好的效果. 相似文献
11.
针对AutoCAD在机械零件课程设计中不能进行参数修改的缺点,本文基于SolidWorks二维工程图介绍了在课程设计中装配工程图的绘制过程、参数的修改和确定,以确保设计过程中对工程图进行参数修改,文中还以二级齿轮减速器为例,探索一种操作简便,可进行参数化修改的绘制工程图的方法。 相似文献
12.
Conclusion As culture is at the heart of meaning making, it warrants exacting attention in the systemic design process. As Gustafson
& Powell (1991) point out, too often models are not tested for validity and reliability. It is for this reason that we emphasize
that research must critically evaluate this expanded ADDIE model.
As technology enables us to increase our interaction with the peoples of the world, we are enriched by the incessant shifts
in our own cultural paradigms. Attention to this cultural dynamism and incessant interplay leads to both improved designs
and improved designers. As instructional designers, we must be able to critically analyze our learner’s cultures and allow
it to strengthen the instructional design process. In this way we address our ethical commitment to creating culturally sensitive
products.
His research interests include culture, identity development, and meaning making in technology rich environments.
His research interests are in the areas of Educational Gerontology, Instructional Design, and the Digital Divide.
His research interests include Systemic Change and the Digital Divide. 相似文献
13.
In order to enhance the reliability of an uncertain structure with interval parameters and reduce its chance of function failure under potentially critical conditions, an interval reliability-based design optimization model is constructed. With the introduction of a unified formula for efficiently computing interval reliability, a new concept of the degree of interval reliability violation (DIRV) and the DIRV-based preferential guidelines are put forward for the direct ranking of various design vectors. A direct interval optimization algorithm integrating a nested genetic algorithm (GA) and the Kriging technique is proposed for solving the interval reliability-based design model, which avoids the complicated model transformation process in indirect ones and yields an interval solution that provides more insights into the optimization problem. The effectiveness of the proposed algorithm is demonstrated by a numeric example. Finally, the proposed direct reliability-based design optimization method is applied to the optimization of a press upper beam with interval uncertain parameters, the results of which demonstrate its feasibility and effectiveness in engineering. 相似文献
14.
工程结构中的复合材料层合板的几何参数往往具有随机性质.如何研究随机参数层合板的灵敏度, 并对参数进行优化分析,这对正确估计结构设计的可靠性有着非常重要的意义.本文用随机摄动法,导出了求反对称层合板响应灵敏度的计算公式,研究了随机参数反对称层合板响应的灵敏度和优化设计,并用网格法计算出最佳铺层角. 相似文献
15.
This study investigated characteristics of bifurcation and critical buckling load by shape imperfection of space truss,which were sensitive to initial conditions.The critical point and buckling load were computed by the analysis of the eigenvalues and determinants of the tangential stiffness matrix.The two-free-nodes example and star dome were selected for the case study in order to examine the nodal buckling and global buckling by the sensitivity to the eigen buckling mode and the analyses of the influence,and characteristics of the parameters as defined by the load ratio of the center node and surrounding node,as well as rise-span ratio were performed.The sensitivity to the imperfection of the initial shape of the two-free-nodes example,which occurs due to snapping at the critical point,resulted in bifurcation before the limit point due to the buckling mode,and the buckling load was reduced by the increase in the amount of imperfection.The two sensitive buckling patterns of the numerical model are established by investigating the displaced position of the free nodes,and the asymmetric eigenmode greatly influenced the behavior of the imperfection shape whether it was at limit point or bifurcation.Furthermore,the sensitive mode of the two-free-nodes example was similar to the in-extensional basis mechanism of a simplified model.The star dome,which was used to examine the influence among several nodes,indicated that the influence of nodal buckling was greater than that of global buckling as the rise-span ratio was higher.Besides,global buckling is occurred with reaching bifurcation point as the value of load ratio was higher,and the buckling load level was about 50%-70% of load level at limit point. 相似文献
16.
推导柱坐标系及球坐标系下流体运动微分方程组通常采用的方法是根据矢量形式的运动微分方程式,利用物质导数的基本公式和正交曲线坐标系各基矢量的偏导数公式来进行,推导过程相当繁琐,尤其在教学过程中,在课堂内完成上述具体推导过程几乎是不可能的。为了寻找一种简捷的推导方法,本文依据基矢量物质导数的基本公式,计算得出了柱坐标系及球坐标系下的基矢量物质导数公式,并将它们分别应用于柱坐标系及球坐标系下的流体运动微分方程组的推导过程中。结果表明:如果将柱坐标系及球坐标系下基矢量的物质导数公式作为基本公式使用,则可以使上述坐标系下流体运动微分方程组的推导过程得到很大程度的简化。 相似文献
17.
烟叶复烤过程具有时滞、不确定、非线性特性,仅利用常规PID控制不能使复烤过程的各项性能指标满足要求,一种参数自适应模糊PID控制器能有效解决这一问题。该控制器的参数调整采用确定性的模糊调整规则,从而不仅使控制器的设计易于实现而且具有很强的适应性和鲁棒性。仿真结果表明,该控制器能对烟叶复烤过程进行有效控制。 相似文献
18.
在不完美生产系统中,以制造商利润最大化为目标,建立了一个决策模型.该模型以生产可靠性和保证期为联合决策变量,考虑了一种产品保证销售策略,即需求依赖于产品保证期和销售价格.并且在不完美生产过程中产生的所有不合格品均以一定的成本返工成合格品.利用Euler-Lagrange方法对模型进行分析,证明了最优生产可靠性和保证期的存在唯一性.通过数值实例证实了模型的有效性,并就关键参数对最优解和最优目标值影响进行了敏感性分析. 相似文献
19.
The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method (RELM) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaebes,RELM method gives a much better understanding of structural failure frequency and its reliability index β is more meaningful. To illustrate this new idea, a specific example is given. 相似文献
20.
比较研究法浅析 总被引：1，自引：0，他引：1
杨柳 《黑龙江教育学院学报》2010,29(6):64-65
比较法在历史科学研究中被普遍采用。没有比较,就不能有鉴别。历史科学的研究非常注重史料的鉴别。因此,我们要利用史料研究问题,就得先鉴别史料的真伪。要鉴别史料,就得运用比较的方法,比较史料的可靠度,才能得到准确而重要的历史材料。 相似文献