Optimization of a plate with holes

We consider a simply supported plate with constant thickness, defined on an unknown multiply connected domain. We optimize its shape according to some given performance functional. Our method is of fixed domain type, easy to be implemented, based on a fictitious domain approach and the control variational method. The algorithm that we introduce is of gradient type and performs simultaneous topological and boundary variations. Numerical experiments are also included and show its efficiency.     

基于改进直接刚度法的损伤评估试验研究

应用改进的直接刚度法对简支梁试验和12层框架振动台模型试验的损伤情况进行了实测数据的初步评估。通过将识别结果与试验报告中不同工况下的损伤描述进行对比,发现文中建议的改进直接刚度法对弯曲类结构的累积损伤进行初步评估是可行和有效的。     

分面成形法金属型铸造Pb-4Sb合金

介绍了在机械加工能力受限制条件下,以较为简易的金属型铸造终成形硬度较小的Pb-4Sb合金铸件.在模具设计方面,提出了分面成形的设计思路;在金属的熔炼上,省去了制取中间合金的过程,成功生产出了不需要机械加工的终成形铸件.     

简单管道水击计算程序的编制与应用

基于求解管道水击的矩形网格法及其算法原理 ,研究了利用特征线法求解水击的方法 ,并用VB6.0语言编制了相应的计算程序 ,在VB上调试通过 ,并结合某简单管道阀门瞬间关闭所产生的水击进行了应用与验算     

简单面目标的雷达散射截面及其物理相似性

雷达目标的散射截面值随目标的形状、大小、电磁波的波长和传播方向而变。本文给出了简单外形导电面目标的雷达散射截面随这些参量改变的一般表示式。利用这个表示式,可从不满足尺寸或波长缩比条件的模型测试值推算原型目标的雷达散射截面值。     

新型悬索桥施工工艺

简支结构体系悬索桥是一种新型的悬索桥结构体系。这种结构能够解决中小跨度时常规悬索桥刚度小、吊杆易疲劳等问题，还能美化景观。介绍该新型结构的特点及主缆的施工技术特点。     

具有简支梁弹性部件包装物品的缓冲

许多可以简化为具有简支梁弹性部件物块的工艺品，在流通过程中由于承受外界的冲击而时常损坏，造成了很大经济损失。本文在考虑弹性部件与物品之间的动力耦合作用基础上，分析了包装系统承受半正弦加速度脉冲激励时的响应，给出了图线和算例，提出了减小物品加速度和弹性部件应力值的措施。     

微机电陀螺随机漂移建模与卡尔曼滤波

微机电系统(MEMS)陀螺精度较低,严重影响制导火箭弹惯导系统的精度.为了减小MEMS陀螺的随机漂移,提高其精度使其满足简易制导火箭弹的精度要求,需要对陀螺信号进行滤波,MEMS陀螺随机漂移建模与补偿是其中的难点.针对上述问题,提出采用自回归移动平均(ARMA)分析的方法建立MEMS陀螺随机漂移模型,然后基于此模型对随机漂移信号进行卡尔曼(Kalman)滤波.对某MEMS陀螺在静止条件下的观测信号的滤波效果表明,ARMA模型拟合度高,能准确描述MEMS陀螺随机漂移特性;Kalman滤波方法能有效减小随机漂移误差,提高MEMS陀螺的精度,对提高简易制导火箭弹的精度具有一定的参考价值.     

Examining the trend in loss of flexural stiffness of simply supported RC beams with various crack severity using model updating

The flexural stiffness of simply supported cracked reinforced concrete beams was determined by model updating. The beams were 150 mm wide, 250 mm deep and 2200 mm long. Different FE models were created which include a datum and models with a single crack at three different locations along the length of the beam. The mode shape equation was obtained by using non-linear regression. The equation used in the regression was the generalized solution of transverse vibration of a prismatic beam. Local flexural stiffness, EI, at each coordinate point was derived by substituting the regressed data by using the centered-finite-divided-difference formula. Experimental modal analysis was performed on a control beam and beams with load-induced cracks at predetermined loading. Results from FE analyses showed the trend in the loss of stiffness was similar to the results obtained on the experimental beams. The more severe the damage, the higher the loss of stiffness and the loss patterns are similar for damage at different locations along the beam. The updating technique is able to indicate the trend in the loss of stiffness as a result of cracks of varying severity in the RC beams showing good agreement with experimental results.     

小麦品质简单检测方法研究

介绍了四种简单的小麦品质检测方法，谷蛋白溶涨指数法能反应谷蛋白含量，面粉溶涨体积能反应小麦的淀粉品质，研磨体积法能反应小麦硬度的差异，发芽率法与食品加工特性密切相关。以上四种方法简单易行，投资小，可信度高，与食品加工特性相关性高，可以替代相应的国标方法进行企业产品和原料的质量控制。