浅析企业财务管理目标与效用函数

本篇文章用“自私的假设和需求定律”来阐述当前我国财务管理目标的几种主要观点,并用效用函数对其进行评析。     

一种用于磁感应断层成像的图像重建算法

磁感应断层成像技术(magnetic induction tomography,MIT)是一种非接触、无损害的以人体电导率分布为成像目标的阻抗成像技术.本文提出一种用于MIT技术的图像重建算法--修正的Newton-Raphson(NR)算法.首先,推导并求解MIT的正问题和逆问题.其次.通过对比仿真计算和实际测量的结果证明基于有限元的MIT正问题求解方法的有效性.然后,对测量区域内的电导率扰动成功地进行了仿真图像重建.结果证明,本文提出的修正的NR算法是一种有效的MIT网像重建算法.它的实现为下一步物理模型以及生物体上的MIT成像实验打下了良好基础.     

一种单源电流激励方法的电阻抗成像仿真及实验

为电阻抗断层成像技术的实际应用选择一种较优的电流激励方法,本文研究了一种单电流源两电极对向激励方法。通过计算机仿真、物理模型实验和初步的动物实验,结合电阻抗成像的反投影算法,与传统的邻近电流激励的电阻抗成像进行比较研究,并分析图像质量、定位误差以及重构误差。结果表明,与邻近激励相比,基于对向激励方法的电阻抗成像的抗噪性能较好。因此在临床较强噪声环境下,对向激励方法更适合于电阻抗成像的实际应用。     

基于Matlab的BP神经网络在泥石流危险性评价中的应用

由于泥石流孕育环境、成灾条件及其诱发因素等的随机性、不确定性和模糊性,决定了泥石流是一种非常复杂的非线性系统。人工神经网络因其具有较强的自组织性、自适应性和自学习能力等优势,更适合于解决非线性问题。本文基于Matlab程序建立了区域泥石流危险性评价的BP神经网络模型,并将该模型应用于凉山州德昌县22个乡镇的区域泥石流危险性评价中,取得了良好的应用效果,评价预测的准确率高达95%。该方法不仅解决了泥石流危险度评价因子和评价等级之间的复杂非线性关系,而且过程简单,结果不受人为因素的影响,是一种具有应用价值、有效的泥石流危险性评价方法。     

高性能混凝土结构复合防裂技术

探讨了冷缩补偿、内养护、控制混凝土含碱量、纤维增强技术,从设计方面提出了复合放裂的技术措施。     

北京将台冬季花园异形拱壳结构分析

北京将台冬季花园钢结构网壳与单向预应力索幕墙结构的建筑外形及受力体系复杂,为满足建筑功能的特殊要求,导致结构部分节点位移及节点局部连接方式不能满足现行规范个别条款的要求;设计通过网壳结构非线性有限元计算和整体稳定性分析复核,证明该网壳结构有足够安全度的同时,也经济合理。     

重庆万豪国际会展大厦超限高层结构设计

介绍了重庆万豪国际会展大厦带加强层钢结构框架 核芯筒结构体系设计的风荷载取值,结构布置, 抗风、抗震计算分析,主要抗震措施、节点构造及结构概念设计,并对大厦的人体舒适度进行了分析。经分析 认为基本对称的高柔结构,风荷载为控制设计的参数。采用外伸桁架是控制结构层间位移的有效方法。     

Module-based similarity measurement for commercial aircraft tooling design

Similarity measurement (SM) between pairs of features plays an essential role in the tooling retrieval. However, the number of tooling is usually large and difficult to retrieve. What’s more, the most similar tooling model is not always optimal in the case-based reasoning (CBR). To refine this situation, we propose a novel module-based similarity measurement method. Through dividing each tooling model into different modules, a new similarity is obtained by integrating all the most similar modules (MSMs) from existing tooling models. As a result, the new similarity is superior or at least equal to the result which is derived from previous methods. With the proposed method in this paper, feature similarities of modules between a new tooling ontology and each similar tooling ontology are calculated by fuzzy similarity measurement, and the MSMs are restructured to form a new tooling model after conflict resolution. A case study on forming mould is provided to illustrate the applications and prove the higher similarity by comparing with CBR. The proposed method has been adopted in an aircraft manufacturing company.     

金属Be真空出气性能的测试

利用四极质谱计测试了国产金属铍材在 10 0℃～ 6 0 0℃不同温度下的真空出气成分及相对含量 ,实验得出铍的大量出气主要在温度 4 0 0℃～ 5 0 0℃之间 ,其放出气体的主要成分按放气量大小依次为H2 O ,CO2 ,N2 ,CO ,Ar和H2 ,利用限流小孔半定量的计算了铍材的出气量。     

Sweeping with electrokinetic injection and analyte focusing by micelle collapse in two-dimensional separation via integration of micellar electrokinetic chromatography with capillary zone electrophoresis

A novel integrated concentration/separation approach involving online combination of sweeping with electrokinetic injection and analyte focusing by micelle collapse (AFMC) with heart-cutting two-dimensional (2D) capillary electrophoresis (CE) in a single capillary was developed for analysis of Herba Leonuri and mouse blood samples. First, a new sweeping with an electrokinetic injection preconcentration method was developed to inject a large volume sample solution and significantly enhance detection sensitivity. Then, the preconcentration scheme was integrated to the 2D-CE to provide significant analyte concentration and extremely high resolving power. The sample was preconcentrated by sweeping with electrokinetic injection and separated in first dimension micellar electrokinetic chromatography (MEKC). Then, only a desirable fraction of the first dimension separation was transferred into the second dimension of the capillary by pressure and further analyzed by capillary zone electrophoresis (CZE) acting as the second dimension. As the key to successful integration of MEKC and CZE, an AFMC step was integrated between the two dimensions to release analytes from the micelle interior to a liquid zone and to overcome the sample zone diffusion caused by mobilization pressure. The injected sample plug lengths for flavonoids under 15 kV for 60 min were experimentally estimated as 546 cm. The dual concentration methods resulted in the increased detection factors of 6000-fold relative to the traditional pressure injection method. The relative standard deviation (RSD) values of peak height, peak area, and migration time were 2.7-4.5%, 1.9-4.3%, and 4.7-6.8% (n = 10), respectively. The limits of detection (S/N = 3) were in the range of 7.3-36.4 ng/L, and the theoretical plate numbers (N) were in the range of 1.7-4.3 × 10(4) plates/m. This method has been successfully applied to determine flavonoids in Herba Leonuri and postdosing mouse blood samples. The pharmacokinetic study also demonstrated that the proposed concentration/separation method was convenient and sensitive and would become an attractively alternative method for online sample concentration and separation in complex samples.