Object-oriented programming for engineering applications

The object-oriented programing (OOP) methodology is introduced as a means for improving the management of a complex engineering software. The drawbacks of existing engineering software development techniques are pinpointed. The basic concepts of the OOP methodology are interpreted in the context of engineering applications. The familiar concept of a matrix is used as an example to interpret the ideas presented. It is concluded that the OOP methodology facilitates the management of complex engineering software systems.     

Object-oriented programming for engineering software development

The representation of engineering systems in a manner suitable for computer processing is an important aspect of software development for computer aided engineering. The process of abstraction is a well-known technique for developing data representations. Objects are a mechanism for representing data using abstraction, and object-oriented languages are languages for writing programs to manipulate objects. The paper shows through examples the advantages of object-oriented programming for developing engineering software. Mathematical graphs are used as an abstraction for two problems: (1) sorting activities in a schedule and (2) ordering nodes and elements in a finite element mesh. Classes of objects are developed for generic graphs, activity procedence graphs, and graphs of elements meshes. Object-oriented program development leads to modular programs and a substantial reuse of code for the two problems.     

A new programming paradigm for engineering design software

Currently available programming and database systems are insufficient for engineering applications. The authors contend that a logical progression from a formal conceptual model of the engineering domain to a computational model will lead to new programming paradigms capable of directly supporting engineering applications in a rigorous, concise manner. A formal domain model devised by the authors, theHybrid Model (HM) of design information, is briefly introduced. It is an extension of axiomatic set theory and is discussed in detail elsewhere. HM forms the basis ofDesigner, a prototype-based object-oriented programming language supporting a signature-based canonical message-passing mechanism and multiple inheritance. Designer is implemented using the Scheme programming language. Because Designer satisfies a formal conceptual model, and because it is based on a formally specified language, its robustness and logical validity are superior to those of other languages not founded on formal principles. Designer combines concepts of functional and object-oriented programming to provide the formal rigor and flexibility to capture the complex and strongly interrelated information that designers use. Examples demonstrate how Designer represents design information. The results of the authors' research indicate that Designer can capture design information (including aspects of functional requirements and design intent) effectively and efficiently.     

Object-oriented programming for structured procedural programmers

Object orientation is attracting much attention these days but may still be unfamiliar to some. This tutorial illustrates the differences between the object-oriented and structured-procedural programming (SPP) paradigms using working programs. It also shows how to migrate from the SPP methodology to object technology     

Ontology paradigm of programming

A new programming paradigm, an ontologic one, which is a developed paradigm of declarative programming, is described, as well as the data model the paradigm is based on and major language structures supported by examples.     

An evaluation of programming languages and language features for engineering software development

This article addresses the need for engineers to have a working knowledge of the fundamental structures of computer programming languages. In pursuit of this, it briefly looks at the history behind four of the more well-known programming languages. It then attempts to identify, and to look critically at, the attributes of programming languages that significantly affect the production of engineering software. The four traditional procedural programming languages chosen for review are those intended for scientific and general purpose programmin—FORTRAN-77, C, Pascal, and Modula-2. These languages are compared and some general observations are made.The emphasis of this article is on the attributes, characteristics, and components of programming languages that are important to software development and maintenance. Consequently, the comparison itself is of secondary importance, with the actual methodology of comparison given prominence in order that professional engineers who need to develop engineering software are able to make rational decisions about the choice of a programming language. Choosing an appropriate language can be a complex task and many factors must be considered. Therefore, in this article the fundamental structures, constructs, and attributes of programming languages are discussed, with very little attention given to the specific syntax of any particular language.     

Object-oriented programming of distributed iterative equation solvers

An object-oriented approach is used to develop classes and frameworks for the implementation of distributed iterative equation solution. The software is implemented using the .NET framework, and builds upon previous work by the author. Development of the framework for iterative solution makes good use of interfaces to isolate sources of complexity. The framework is used for three different solution scenarios (i) conjugate gradient iteration on a single matrix; (ii) conjugate gradient iteration when domain decomposition is used; and (iii) using the Schur complement approach. Moreover, the framework is used for both local and remote objects. The .NET framework makes it very straightforward to program distributed applications, and the object-oriented approach greatly facilitates the software development. The framework was used in a finite element program and the speed-up results are shown.     

Science Code .Net: Object-oriented programming for science

We propose an object-oriented programming library system for Science in a similar structure of .NET framework. We call the system Science Code .Net. Presenting rules of thumb, we show how to enhance readability of Science Code .Net. As an initial progress, several namespaces have been constructed. We explain the structure of classes in each namespace. As a challenge to the programming community, a perspective view of Science Code .Net is discussed.     

A programming language for engineering computations

C-Map was initially developed for computer-aided instruction in structural analysis and design; however, its present capability extends far beyond, to cover a broad spectrum of numerical methods for engineering computations ranging from elementary calculus to nonlinear constrained optimization problems. The flexibility and power of C-Map derive from the technique of recursive nesting of functions which releases the power of previously isolated, yet robust, algorithms. Such capability far surpasses that of the most comprehensive collection of FORTRAN scientific subroutine package. C-Map comprises four integrated components: (i) a full-screen text editor with multiple stacked windows for simultaneous editing of programs and output files; (ii) a simplified C-like programming language with the basic control structures do-while, while, for, if/else, recursive functions, math library, built-in functions for advanced engineering computations including matrix operations for structural analysis; (iii) an interactive expression evaluator; and (iii) a simple authoring system with automatic cross-referencing of key-words. The program's versatility helps to meet the different needs of users at different stage of learning. A beginner may use only the built-in functions for math and matrix operations to get immediate, useful results; and the advanced users may write their own functions for more complex problems. This paper discusses the features of C-Map and its applications in teaching structural engineering.     

A simulation-based design paradigm for complex cast components

This paper describes and exercises a new design paradigm for cast components. The methodology integrates foundry process simulation, non-destructive evaluation (NDE), stress analysis and damage tolerance simulations into the design process. Foundry process simulation is used to predict an array of porosity-related anomalies. The probability of detection of these anomalies is investigated with a radiographic inspection simulation tool (XRSIM). The likelihood that the predicted array of anomalies will lead to a failure is determined by a fatigue crack growth simulation based on the extended finite element method and therefore does not require meshing nor remeshing as the cracks grow. With this approach, the casting modeling provides initial anomaly information, the stress analysis provides a value for the critical size of an anomaly and the NDE assessment provides a detectability measure. The combination of these tools allows for accept/reject criteria to be determined at the early design stage and enables damage tolerant design philosophies. The methodology is applied to the design of a cast monolithic door used on the Boeing 757 aircraft.     

Ultimate strength analysis of structural components using the continuum damage mechanics approach

In this study, an analytical model is developed to include the effect of material fracture on the overall behavior of a structure. The continuum damage mechanics approach is used to describe the continuous deterioration of the material stiffness that leads to total failure. The damage evolution is assumed to be anisotropic and the effect of the triaxiality of stress on the fracture criterion is included in the analysis. The above modifications were applied to an existing finite element program which is capable of including both geometric and material nonlinearities in the analysis. The program was used to analyze a welded tubular connection (T-joint). This joint was chosen because fracture was shown experimentally to control its ultimate behavior. Solid finite elements were used to model the chord and the branch in the intersection region, wedge elements were used for the weld profile, and the rest of the geometry was modeled using shell elements. The joint was subjected to an increasing amount of displacement at the far end of the branch. The loading was continued until total failure. During this process, the evolution of the damage and its propagation were monitored. Divergence of the solution was obtained at a failure load of 42.4 kips compared to 44.0 kips obtained experimentally. In addition, the failure mode of the joint predicted by the analysis was identical to that observed experimentally.     

A comparison of programming languages for software engineering

Four programming languages (Fortran, Cobol, Jovial and the proposed DoD standard) are compared in the light of modern ideas of good software engineering practice. The comparison begins by identifying a core for each language that captures the essential properties of the language and the intent of the language designers. These core languages then serve as a basis for the discussion of the language philosophies and the impact of the language on gross program organization and on the use of individual statements.     

基于Lamb波结构损伤诊断的量化评估实验研究

基于Lamb波结构损伤诊断技术开展相对量化评估层面的实验研究.基于环形单发射—多接收(STMR)阵列,通过数值计算验证了基于导波结构损伤诊断技术在定位识别技术层面的准确有效;针对诊断因子(DF)作为结构损伤相对量化评估有效参数的可行性进行分析,并通过模拟预置3种不同程度大小的损伤进行实验验证.实验结果表明:通过比较不同工况下判定损伤处对应诊断因子的数值大小,即可对结构损伤的相对严重程度进行量化对比分析,具有较好的工程应用前景.     

Efficient programming paradigm for video streaming processing on TILE64 platform

Advances at an unprecedented rate in computer hardware and networking technologies have made the many-core computing affordable and readily available in a matter of few years. Nonetheless, it incurs challenges to programmers to build scalable parallel software. Optimizations of parallel programs for a many-core platform are viewed as a multifaceted problem, where system and architectural factors should be taken into account. In this paper, we tackle this problem by implementing parallel programs with different available programming paradigms and evaluate application behaviors on TILE64 many-core platform. That is, we investigate a hybrid producer-write plus consumer-read shared memory programming paradigm for the implementation of master–worker video decoder and encoder in the referred many-core platform. Experimental results show that the proposed implementation has achieved competitive performance speedup, scaling well with the number of available cores and up to four times of performance improvement over other implementations on the decoding of sample 1080P video.     

Form/formula: a visual programming paradigm for user-definable userinterfaces

We have designed and implemented a visual programming environment, Hyper-flow on the PenPoint operating system. We call it HF/PP for short. Its primary goal is to provide a framework for UDUI in educational applications. The design of HF/PP, which uses only a pen and a microphone for input, is part of a research project to develop a pen based computer system for teaching preschool through twelfth grade mathematics. The article discusses the UDUI capabilities of HF/PP, represented by the programming constructs; form and formula, or the form/formula paradigm. To explain the paradigm, and other HF/PP constructs, we present three examples: converting between Fahrenheit and Celsius, designing arithmetic worksheets, and querying student records     

Anonymous remote computing: a paradigm for parallel programming oninterconnected workstations

Parallel computing on interconnected workstations is becoming a viable and attractive proposition due to the rapid growth in speeds of interconnection networks and processors. In the case of workstation clusters, there is always a considerable amount of unused computing capacity available in the network. However, heterogeneity in architectures and operating systems, load variations on machines, variations in machine availability, and failure susceptibility of networks and workstations complicate the situation for the programmer. In this context, new programming paradigms that reduce the burden involved in programming for distribution, load adaptability, heterogeneity and fault tolerance gain importance. This paper identifies the issues involved in parallel computing on a network of workstations. The anonymous remote computing (ARC) paradigm is proposed to address the issues specific to parallel programming on workstation systems. ARC differs from the conventional communicating process model by treating a program as one single entity consisting of several loosely coupled remote instruction blocks instead of treating it as a collection of processes. The ARC approach results in distribution transparency and heterogeneity transparency. At the same time, it provides fault tolerance and load adaptability to parallel programs on workstations. ARC is developed in a two-tiered architecture consisting of high level language constructs and low level ARC primitives. The paper describes an implementation of the ARC kernel supporting ARC primitives     

Automatic structural identification and relaxation for integer programming

This research investigates the automatic identification of typical embedded structures in the Integer Programming (IP) models and automatic transformation of the problem to an adequate Lagrangian problem which can provide tight bounds within the acceptable run time. For this purpose, the structural distinctivenesses of variables, constants, blocks of terms, and constraint chunks are identified to specify the structure of the IP model. To assist the identification of the structural distinctiveness, the representation by the knowledge based IP model formulator, UNIK-IP, is adopted. To reason for the structural identification, the hybrid of bottom-up, top-down, and case-based approaches are proposed. A system UNIK-RELAX is developed to implement the approaches proposed in this research.     

Proportioning of structural components

The current use of special purpose and general purpose programs by structural engineers to proportion structural components has been reviewed. The first class of structures considered is that in which adequate strength is the only criterion. The second class is concerned with structures where both strength and stiffness must be adequate. A recommendation and illustration of proportioning program output is given which should increase the acceptance of ‘design by computer’ within the profession.