Computer-aided optimum design of steel tubular telescopic pole structures

This paper presents a computer-aided approach for the optimum design of steel tubular telescopic pole structures. The author's experience in steel pole structure's design is implemented in a computer program called ODAPS (optimum design and analysis of pole structures). Although several other computer programs exist for the analysis and design of steel tubular pole structures, they are limited to cases where dimensions are pre-defined by the user. Different from these conventional programs, the developed program is able to automatically design the pole structure having the lightest weight that satisfies the limits states criteria within given geometrical boundary conditions. Simple equations and charts for the design of poles of different steel grade and having different length, subjected to various point loads at their top, are obtained using this program. It is possible to obtain economical designs for pole structures subjected to a specified loading using these equations or charts.     

Semantic inheritance in unifying theories of programming

This paper introduces a number of new techniques that support systematic manipulation of predicates, operators, healthiness conditions, laws and fixpoints of recursive programs. Necessary restrictions are imposed on the definition of each model so that the inheritance relation can be established by checking a few conditions on the healthiness conditions and the commands. In particular, we intend to identify the conditions that simplify the closure proof of the program operators and enable laws and fixpoints of a model to be inherited by its submodel without re-proof. A recursive program may correspond to different recursive functions in a model and its submodels, because the primitives such as abort and assignment statements are normally represented as different predicates in different models (although the original definition of each operator is unchanged). This paper studies meta-theory in this more general setting. A fixpoint theorem is discovered and applied to clarify the relationship between the partially correct relational model and the totally correct sequential model in UTP. It is shown that, although assignment statements are modified by the new healthiness conditions in the latter model, most laws (including many that are re-proved in UTP) and fixpoints can be inherited directly without re-proof, if the first argument of every sequential composition in each command tree corresponds to a terminating computation. This result also singles out a small number of laws and fixpoints that may no longer hold in the totally correct model.     

铁芯片数控横剪生产线中的速度同步控制

横剪线是变压器铁芯硅钢片生产的专用设备,可将一定宽度的硅钢卷料按照操作者预先编制的程序剪切成各种形状硅钢片料.由于整条生产线上的送料轨道较长,为了保证剪切精度,使硅钢片在导轨中能够高速平稳的传送,就需要在送料导轨上安装一台拉料电机.本文主要介绍如何使拉料电机与送料电机实现速度的匹配.     

基于PLC的绕组线圈真空干燥系统的设计

目前厂家对浸漆绕组线圈的干燥主要使用传统热风循环的方法,而且关于浸漆绕组线圈的干燥工艺研究尚不充分;针对传统绕组浸漆线圈干燥时间长,干燥所得线圈表面绝缘性能欠佳等问题,设计研发了一套自动化程度较高的绕组浸漆线圈真空干燥系统;该系统主要由真空单元、温度控制单元、电气控制单元、人机交互单元等部分组成;通过将浸漆线圈放置于真空环境中,对浸漆线圈进行通电的方式来加热干燥,以可编程逻辑控制器为核心,利用PLC的PWM输出功能控制加热,同时提出了浸漆线圈干燥的均匀设计实验方案,得出了最佳实验干燥工艺,最后通过对实验数据的回归分析得出了各实验指标之间的关系及显著性影响;实验结果表明:该系统不仅缩短了浸漆线圈的干燥时间,而且使浸漆线圈表面的绝缘性能有了明显的提高。     

带磁芯励磁线圈的阻抗匹配

带磁芯励磁线圈的阻抗匹配是磁致伸缩器件设计和应用的基础.为使励磁线圈产生较大磁场,利用AMH-1M-S型磁特性测试系统,测试了在不同频率下线圈磁芯材料硅钢片的B-H和u-H曲线,同时计算了带磁芯励磁线圈的复阻抗.根据串联谐振电路原理,理论上计算了电路谐振时的电容值.搭建了实验平台,利用示波器采集电源电压和串接在电路中采样电阻电压的数值,计算了串接匹配电容前后电路的阻抗变化.实验结果表明:串接匹配电容后,在励磁电流频率为50 Hz、100 Hz、150 Hz时,励磁线圈总阻抗下降了48.95%、61.34%、60.06%,励磁电流分别增加了95.88%、158.62、150.38%.     

Optimum design of steel frames with stability constraints

Optimum design algorithms based on the optimality criteria approach are proven to be efficient and general. They have the flexibility of accomodating variety of design constraints such as displacement, stress, stability and frequency in the design problem. The design methods developed recently, although considering one or more of these constraints, lack the necessity of referring to any relevant design code. The algorithm presented for the optimum design of street frames implements the displacement and combined stress limitations according to AISC. The recursive relationship for design variables in the case of dominant displacement constraints is obtained by the optimality criteria approach. The combined stress inequalities which include in-plane and lateral buckling of members are reduced into nonlinear equations of design variables. The solution of these equations gives the values of bounds for the variables in the case where the stress constraints are dominant in the design problem. The use of effective length in the combined stress constraints makes it possible to study the effect of the end rigidities on the final designs. The design procedure is simple and easy to program which makes it particularly suitable for microcomputers. A number of design examples are considered to demonstrate the practical applicability of the method. It is also shown that the design procedure can be employed in selecting the optimum topology of steel frames.     

基于递归法在C语言项目实践中的探索和应用

在用C语言进行项目实践的时候经常会遇到算法的设计问题,算法设计的好坏以及效率的高低直接影响和决定着项目实践的成败,因此,算法设计是解决问题的核心和关键。在诸多算法当中,递归是一种比较另类和难于理解的算法,但由于它的强大功能,在进行项目实践和应用程序开发时常常采用递归算法来解决问题。尝试通过详述几个典型项目的求解过程,探索递归算法的使用方法和技巧,提高使用C语言程序设计解决实际问题的能力。     

The production of interactive engineering design software using Borland Delphi

Advances in PC programming systems allow the development of highly interactive engineering design software. Software can work in a way which is obvious to the user, and gives considerable feedback during and after the analysis. If an indication is given of the cost of a design, the user can concentrate on making design decisions, rather than on the mechanics of the analysis. Such programs can be developed to run themselves, making changes to the data and carrying out analysis until an optimum design has been reached. These possibilities are illustrated using a program for the design of reinforced soil structures.     

Using Canny's criteria to derive a recursively implemented optimal edge detector

A highly efficient recursive algorithm for edge detection is presented. Using Canny's design [1], we show that a solution to his precise formulation of detection and localization for an infinite extent filter leads to an optimal operator in one dimension, which can be efficiently implemented by two recursive filters moving in opposite directions. In addition to the noise truncature immunity which results, the recursive nature of the filtering operations leads, with sequential machines, to a substantial saving in computational effort (five multiplications and five additions for one pixel, independent of the size of the neighborhood). The extension to the two-dimensional case is considered and the resulting filtering structures are implemented as two-dimensional recursive filters. Hence, the filter size can be varied by simply changing the value of one parameter without affecting the time execution of the algorithm. Performance measures of this new edge detector are given and compared to Canny's filters. Various experimental results are shown.     

Elastic - plastic design of unbraced frameworks

A computer program for the optimum elastic-plastic design of two-dimensional steel frameworks is described, and design examples are presented. These examples are used as a basis for comment on some of the assumptions adopted in the program. The paper also compares and contrasts the philosophy used in the program with other approaches reported in the literature.     

非导磁金属隔层对差动变压器式位移传感器的影响

针对加入到差动变压器铁芯和衔铁之间的非导磁金属隔层对差动变压器式位移传感器性能的影响进行了研究.通过分析非导磁金属隔层上产生的电涡流得到加入非导磁金属隔层后差动变压器式位移传感器输出模型,应用MATLAB仿真得到非导磁金属隔层电导率、线圈激励频率和隔层与线圈距离对传感器性能的影响;对加入非导磁金属隔层后的传感器进行静态...     

LDC1000电感数字传感器的转速测量设计

不同于传统检测转速的方法,本测量方法在金属齿轮转速的检测方法中提出了新的设计思路,以LDC1000电感数字传感器为核心,以低功耗、低成本的MSP430F149为主控芯片,加上自制电感线圈来完成转速测量.射频收发芯片nRF24L01作为转速信息数据传输装置,发展前景良好.本文分析了转速测量的理论依据,给出电路原理图及其程序流程,实现对金属齿轮的转速测量、数据的传输共享.     

Optimization of nonhomogeneous facesheets in composite sandwich plates

The optimal design of composite sandwich plates in which the facesheets are composed of a carbon fiber/epoxy net is considered. The objective of the work is to obtain minimum mass designs while maintaining constraints on the first natural frequency and selected facesheet stress components. The facesheets are assumed to be composed of an orthotropic net of unidirectional composite fiber strips and the optimal design (the least mass design) is achieved by changing the strip widths and the spacings between them. It is demonstrated that varying the spatial fiber strip distribution can lead to significant structural advantages; in the example presented, a 32% facesheet mass reduction is achieved.     

基于规格说明的若干逻辑覆盖测试准则

基于规格说明的测试可以在不需要了解软件程序代码的情况下对软件进行功能测试.判定是形式规格说明中用于描述前、后置条件的主要形式.分析了基于规格说明的逻辑覆盖测试准则,针对已有的决定性逻辑覆盖测试准则的不足,提出了掩盖性逻辑覆盖测试准则,并对其进行了详细分析.提出了掩盖性逻辑覆盖测试准则的一个可行的测试生成算法.根据该准则生成的测试用例能够发现条件的掩盖性带来的错误.然后,从判定的结构入手,分析了条件之间的约束关系、复杂判定的分解与合成、判定之间的关系.这些分别能够阐明逻辑覆盖中条件间的耦合性问题、同一个条件在判定中的多次出现问题以及判定在程序中的位置问题.继而提出了全真判定覆盖、全假判定覆盖、完全子判定覆盖、唯一条件真覆盖以及唯一条件假覆盖等测试准则.满足这些测试准则的测试用例集能检测出不同类型的错误.最后,给出了这些测试准则之间的包含关系图,并建议了不同测试准则适用的应用场景.     

An integrity filter for recursive subdivision meshes

We present a filter, i.e., a simple program operating on a sequential file and requiring little internal storage, for mending “cracks” between patches formed by recursively subdividing a parametric surface. Our approach shows how various new encoding schemes and processing techniques related to quadtrees can be transposed into the setting of recursive subdivision surfaces.     

基于规格说明的若干逻辑覆盖测试准则

基于规格说明的测试可以在不需要了解软件程序代码的情况下对软件进行功能测试.判定是形式规格说明中用于描述前、后置条件的主要形式.分析了基于规格说明的逻辑覆盖测试准则,针对已有的决定性逻辑覆盖测试准则的不足,提出了掩盖性逻辑覆盖测试准则,并对其进行了详细分析.提出了掩盖性逻辑覆盖测试准则的一个可行的测试生成算法.根据该准则生成的测试用例能够发现条件的掩盖性带来的错误.然后,从判定的结构入手,分析了条件之间的约束关系、复杂判定的分解与合成、判定之间的关系.这些分别能够阐明逻辑覆盖中条件间的耦合性问题、同一个条件在判定中的多次出现问题以及判定在程序中的位置问题.继而提出了全真判定覆盖、全假判定覆盖、完全子判定覆盖、唯一条件真覆盖以及唯一条件假覆盖等测试准则.满足这些测试准则的测试用例集能检测出不同类型的错误.最后,给出了这些测试准则之间的包含关系图,并建议了不同测试准则适用的应用场景.     

A fortran program for the design of laminates with required mechanical properties

A FORTRAN 77 program for designing laminates with required mechanical properties is presented. This user-friendly program is developed for interactive use by users with either micro or mainframe computers to provide maximum flexibility and reduce the amount of inputting. The inputs required to the program are layer orthotropic unidirectional (UD) material properties and thickness and the desired laminate mechanical properties. The output is the optimum lamination that will provide these properties. This optimum is obtained by minimizing the difference between the calculated properties of trial laminates and the desired properties. The program allows such designed laminates to be unsymmetric in either geometry or material about the middle surface of a plate and consist of a specified number of different fibre-reinforced orthotropic layers. This program can either be used on its own for the purpose of designing laminated plates or be considered as a package-subroutine within a complex structural design package. As a demonstration of the use of the program, the design of a symmetric laminate is conducted to show how an optimal lay-up sequence can provide the required laminate mechanical properties determined by the design. A full listing of the program is given as an Appendix.     

一类递归编程的特殊方法探讨

介绍了递归模型的一般形式、递归程序的执行过程及递归程序设计.重点从数学公式的角度探讨了复杂递归问题的一类特殊编程方法及其应用.     

基于逻辑程序的免疫识别器动态覆盖性初探

免疫识别器的动态覆盖与人工免疫系统的有效性具有重要的关联关系,应该用尽可能少的识别器覆盖尽可能多的NONSELF空间。根据识别器的动态覆盖性原理,引入逻辑程序来表示免疫识别器,并运用逻辑程序的更新特性,试图消除识别器所识别出的NONSELF空间的冗余,降低识别器的浓度,增强识别器的动态覆盖性。