The use of the object oriented programming approach in developing applications for the analysis and design of reinforced concrete structures is discussed. Two object oriented programming languages, Actor and Borland C++ for Windows were used to develop several applications. Actor is a pure object oriented programming language while C++ is a hybrid object oriented programming language. A simple program for computing the flexural capacity of reinforced concrete tee beams was developed in both languages. A second program for the analysis and design of reinforced concrete continuous beams was developed in Actor and C++. This application is representative of a practical structural engineering application and has both analysis and design components. The procedures and techniques used in the development of this application can easily be applied to the development of other structural engineering applications. A third program for the design of simply supported beams was also developed in Actor. The advantages and disadvantages of object oriented programming for structural engineering application development were studied. It was found that object oriented programming has significant benefits. However, these benefits can only be utilized if careful thought is given during the program development stage. There is also some overhead associated with object oriented programming. A comparative study of the two programming languages: Actor and Borland C++ was also performed. / Master of Science

This thesis discusses the research and development of a program to aid the aircraft designer with determining the pilot's visual acuity. The discussion involves the use of Object-Oriented programming, the use of a graphical user interface based upon the graphics standard PHIGS (Programmers Hierarchical interactive Graphics System) and the integration of this Pilot's View Module with an existing aircraft CAD (Computer Aided Design) program known as ACSYNT. The result is a program that lends itself to reuse and easy modification and is device independent. The main purpose of the pilot's view module is to provide total vision plots for the pilot in accordance with the military standards as stated in the document 850B. These standards include visibility design goals for several types of aircraft as well as methods for calculating and presenting the vision plots. The integration of the pilots view module with ACSYNT affords the designer the ability to examine the trade-offs associated with a particular cockpit design and the performance of that design within one CAD program. / Master of Science

The use of computers in the area of design and manufacturing is commonplace in industry. Many companies are turning to custom designed in-house software to surpass the competition. A growing number are developing knowledge-based expert systems to capture the knowledge of expertise of employees before they retire. The use of traditional artificial intelligence languages can be cumbersome to engineers who are usually familiar with traditional languages such as FORTRAN and C. The use of expert systems shells can often hinder the customization of an expert system due to limitations of the shell. An alternate approach to these methods is the use of an object-oriented framework that facilitates the creation of customized expert systems. This framework, called the Expert Consultation Environment, alleviates the programming problems of expert system development and allows the engineer to concentrate on knowledge acquisition. This thesis describes the design of the rule classes needed by the framework. These are the base Rule class, the Equation Rule class, the Control Rule class, the Constraint Rule class and the Heuristic Rule Class. Also presented, is the development of a methodology used in creating an expert system with the framework. A prototype expert system developed using the framework for parametric, multi-disciplinary, conceptual design of aircraft is described. / Master of Science

Since the availability of the first PHIGS (Programmers Hierarchical Interactive Graphics System) implementation in the mid 1980’s, interest in the use of PHIGS has been steadily growing among the CAD applications developer’s community. Every year, more PHIGS-based CAD applications programs are being created to ensure portability and make use of the high-level support provided by PHIGS [JAYA93b]. One of the common uses of computer graphics in engineering is for the creation of graphs. Commonly used graphs, such as line graphs (two-dimensional or three-dimensional), bar charts, pie charts, surface plots, etc., can be created using PHIGS. This involves the creation of several methods to scale the data, draw the graph, display labels, display axes, display legends and several other programming tasks, which are re-created by each applications program. This thesis describes the creation of an object-oriented class library to facilitate the creation of engineering graphs using PHIGS. This library provides the programmer with a set of tools to create commonly used graphs (line graphs, pie charts, bar charts, polar plots, and 3D plots). The class library will allow PHIGS programmers to quickly and easily create graphs for use with applications programs. This set of classes uses a PHIGS-based, Motif-like interface framework (described by Woyak and Myklebust [WOYA93]). User interface methods to allow the end-user of the graphing program to modify attributes of the graph (e.g. line types, legends, colors, etc.) are encapsulated within this class library and are hidden from the programmer using these classes. The library of classes, the user interface methods, and the use of this system is described in this thesis. / Master of Science

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This dissertation presents a new alternative type of object-oriented load-flow called Segflow. Segment objects are used to support the modeling of individual types of power system equipment. Current and voltage trace techniques are used by Segflow to bind Segment models in support of Kirchoff’s laws. Affiliation objects and the Target Voltage method are used to bring the solution of the Segflow model to the solution of the power system network. An example for modeling a simple transformer is given along with the solution results for a collection of common power system models. ‘ Analysis of the Target Voltage method and simulation results show that Segflow is capable of consistently solving the nonlinear load-flow problem. The object-oriented layout of Segflow provides very distinct modeling advantages. Power system modeling is from the perspective of each equipment’s model. Rather than force all equipment models into large sets of equations to be solved simultaneously by an equation solver, Segflow allows component models to remain intact and independent as Segment objects. Each Segment has a one-to-one correspondence with some piece of equipment in the respective power system which is maintained in the system solution. The behavior of a Segment can be evaluated throughout the load-flow process. An important feature of Segflow is the object-oriented design enabling new equipment models to be added into the Segflow environment as autonomous objects. New models are created from the Segment class and their inputs and outputs are always relative to the same Segment attributes. Because all Segment objects are derived from a Segment modeling class and all Segments are treated the same by Segflow, many types and varieties of power system equipment models can be easily created. A Segflow application is a collection of interacting objects whose interactions lead to a load-flow solution. Segflow is an interesting alternative to classical approaches for solving the load-flow problem with large sets of simultaneous nonlinear equations. It also adds new aspects to the application of object-oriented design in load-flow analysis. / Ph. D.

A prototype of an object-oriented structural analysis program is presented in order to explore object-oriented programming as a viable alternative to procedural programming. Modeling concepts are discussed with respect to procedural programming and object-oriented programming. Through the constructs provided by object-oriented programming, the program's components and component behavior are modeled as one-to-one analogies of their respective real world counterparts. Thus, like a real world structure, a structure in the program is composed of nodes, elements, and loads. The traditional fixed global stiffness matrix is replaced by a dynamic node network allowing the structure to be constructed dynamically. Implementing vector algebra with object-oriented programming removes the need for any explicit global to local or local to global coordinate transformations. These techniques provide a foundation for constructing a visually-oriented analysis and design environment. / M.S.

Since the 1960's an overwhelming amount of in-house and custom engineering software has been written. In the effort to reduce the cost of maintaining existing codes and producing new applications, the recent introduction of the object-oriented design approach has proved successful. At the same time graphical user interfaces are gaining in popularity to improve the usability and versatility of an application. This thesis investigates the application of the object-oriented approach to the design of a graphical user interface for an engineering design application. The development of an object-oriented graphical user interface for the NASA Engine Performance Program, a turbine engine design code is presented. The design of the new object-oriented graphical user interface for extensibility and re-usability is discussed. Design considerations for integration of the interface with procedural and object-oriented versions of the conceptual aircraft design program, ACSYNT, are explained. An existing PHIGS-based object-oriented graphical user interfacing framework is extended and built upon to develop the class structure of the interface. The class organization is presented in commonly used notation and described in detail. / Master of Science