Design patterns in software systems are described as a universal reusable solution to a commonly recurring problem in software design. Design patterns were, however, not intended to be reusable in terms of code. A symptom of their non-reusability is the problems experienced with the way the implementation of design patterns negatively affects their traceability, maintainability and contribution to productivity. This thesis shows how design patterns can be elevated to a higher level of reusability. This work presents design patterns as reusable components that developers can use to implement solutions that utilise patterns, without having to implement a major part of a pattern’s structure and behaviour anew each time. A component is a reusable software section, with possible library classes, that is usually in source form. Previous research has shown that a high proportion of patterns (65%) can be “componentized” in Eiffel, which leads to the idea that a language supporting the same set of features would also have the same success in pattern componentization. This thesis has looked at the componentization of twelve design patterns in C#. The C# language has more advanced language features than Eiffel, including functional and dynamic language features and, as such, should lend itself better to pattern componentization than Eiffel does. The language features that are reviewed in this thesis are inheritance, design by contract™, attributes, method references (or delegates), anonymous functions, lambda expressions, mixins (or extension methods), duck typing, dynamic types and meta-programming. Each pattern’s reusable components are discussed in detail, including the success of the reusable component transformation. All the design patterns reviewed in this thesis could be transformed into fully or partially reusable components. Implementing design patterns using reusable library components is thus a step in the right direction in making design pattern implementations more traceable, reusable, maintainable and more productive. Other object-oriented languages implementing the same or similar language features as those reviewed in this thesis should have the same level of success in transforming design patterns into reusable components. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Computer Science / unrestricted

Designing software components for future reuse has been an important area in software engineering. A software system developed with reusable components follows a "with" reuse process while a component designed to be reused in other systems follows a "for" reuse process. This dissertation explores the factors affecting design for reuse and design with reusable components through empirical studies. The studies involve Java components implementing a particular algorithm, a stemming algorithm that is widely used in the conflation domain. The method and empirical approach are general and independent of the programming language. Such studies may be extended to other types of components, for example, components implementing data structures such as stacks, queues etc. Design for reuse: In this thesis, the first study was conducted analyzing one-use and equivalent reusable components for the overhead in terms of component size, effort required, number of parameters, and productivity. Reusable components were significantly larger than their equivalent one-use components and had significantly more parameters. The effort required for the reusable components was higher than for one-use components. The productivity of the developers was significantly lower for the reusable components compared to the one-use components. Also, during the development of reusable components, the subjects spent more time on writing code than designing the components, but not significantly so.  A ranking of the design principles by frequency of use is also reported. A content analysis performed on the feedback is also reported and the reasons for using and not using the reuse design principles are identified. A correlation analysis showed that the reuse design principles were, in general, used independently of each other. Design with reuse: Through another empirical study, the effect of the size of a component and the reuse design principles used in building the component on the ease of reuse were analyzed. It was observed that the higher the complexity the lower the ease of reuse, but the correlation is not significant. When considered independently, four of the reuse design principles: well-defined interface, clarity and understandability, generality, and separate concepts from content significantly increased the ease of reuse while commonality and variability analysis significantly decreased the ease of reuse, and documentation did not have a significant impact on the ease of reuse. Experience in the programming language had no significant relationship with the reusability of components. Experience in software engineering and software reuse showed a relationship with reusability but the effect size was small. Testing components before integrating them into a system was found to have no relationship with the reusability of components. A content analysis of the feedback is presented identifying the challenges of components that were not easy to reuse. Features that make a component easily reusable were also identified. The Mahalanobis-Taguchi Strategy (MTS) was employed to develop a model based on Mahalanobis Distance  to identify the factors that can detect if a component is easy to reuse or not. The identified factors within the model are: size of a component, a set of reuse design principles (well-defined interface, clarity and understandability, commonality and variability analysis, and generality), and component testing. / Ph. D.

Yes / To determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. Across four sites, 74 neophytes (18-28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0-100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4-6 days and 12-14 days after lens fitting. Subjective scores were also repeated after 7 days. There was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4-6 days, but was similar by 12-14 days. Subjective scores were also similar across the visits and lens types with the exception of 'lens awareness' (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12-14 days. There seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients. / BUCCLE

This research involves review of value analysis and value engineering techniques and application of these techniques to a service organization. Application of value analysis techniques to service organizations required some modification due to the amount of labor intensive, manual operations typical of many service industries. The modified value analysis methodology was applied to a fueling operation performed by Kennedy Space Center as part of their space shuttle operations. The successful application of this technique illustrated that value analysis methodology can be applied to service organizations with slight modifications.

A recently developed viscous shock-layer method (VSL81) has been applied to predict laminar viscous flows over the windward surface of a shuttle-like vehicle with a perfect gas and an equilibrium air model at high angles-of-attack to simulate reentry conditions. The predictions of wall pressure and heat-transfer data compare well with the limited experimental data available requiring relatively short computing times compared to parabolized Navier-Stokes (PNS) methods. Velocity, pressure and enthalpy profiles are compared at some stations on the body. This method can be used to predict viscous flows over general lifting bodies during reentry. / Master of Science

During development of a complex system, feasibility initially overshadows other concerns, in some cases leading to a design which may not be viable long-term. In particular for the case of Reusable Launch Vehicles, Operations&Maintenance comprises the majority of the vehicle's LCC, whose stochastic nature precludes direct analysis. Through the use of simulation, probabilistic methods can however provide estimates on the economic behavior of such a system as it evolves over time. Here the problem of operations optimization is examined through the use of discrete event simulation. The resulting tool built from the lessons learned in the literature review simulates a RLV or fleet of vehicles undergoing maintenance and the maintenance sites it/they visit as the campaign evolves over a period of time. The goal of this work is to develop a method for uncovering an optimal operations scheme by investigating the effect of maintenance technician skillset distributions on important metrics such as the achievable annual flight rate and maintenance man hours spent on each vehicle per flight. Using these metrics, the availability of technicians for each subsystem is optimized to levels which produce the greatest revenue from flights and minimum expenditure from maintenance.

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Development of an extended test range, with range instrumentation providing continuous vehicle communications, is required to flight-test the X-33, a scaled version of a reusable launch vehicle. The extended test range provides vehicle communications coverage from California to landing at Montana or Utah. This paper provides an overview of the approaches used to meet X-33 program requirements, including using multiple ground stations, and methods to reduce problems caused by reentry plasma radio frequency blackout. The advances used to develop the extended test range show other hypersonic and access-to-space programs can benefit from the development of the extended test range.

The next generation of reusable launch vehicles (RLVs) require significant improvements in guidance methods in order to reduce cost, increase safety and flexibility, whilst allowing for possible autonomous operation. Research has focused on the ascent and hypersonic re-entry flight phases. This thesis presents a new method for trajectory design, optimisation and guidance of RLVs during the terminal area flight phases. The terminal area flight phase is the transitional phase from hypersonic re-entry to the approach and landing phase. The trajectory design, optimisation and guidance methods within this thesis are an evolution of previous work conducted on the ascent and re-entry flight phases of RLVs. The methods are modified to incorporate the terminal area flight phase through the adaption of the problem definition and the inclusion of the speed brake setting as a steering parameter. The methods discussed and developed in this thesis are different to previous methods for the terminal area flight phase as they encompass optimisation, trajectory design and guidance based on the definition of the steering parameters. The NLPQL nonlinear optimiser contained within the International Mathematics Standards Library (IMSL) is utilised for trajectory design and optimisation. Real-time vehicle guidance is achieved using the restoration steps of an accelerated Gradient Projection Algorithm (GPA). The methods used are evaluated in a three degrees of freedom (3DOF) simulation environment. To properly evaluate the programs and gain a better understanding of the terminal area flight phase, two different vehicles are utilised within this study. These vehicles are the German sub-orbital Hopper concept vehicle, a previously proposed replacement for the Ariane series of launch vehicles and the recently cancelled joint National Aeronautics and Space Administration (NASA) and Lockheed Martin sub-orbital test bed vehicle, X-33. The two vehicles each have a terminal area flight phase, but their mission profiles and vehicle characteristics are significantly different. The Hopper vehicle is a winged re-entry vehicle, whereas the X-33 vehicle is a lifting body. The trajectory design method takes into account the initial and final conditions, in-flight restrictions such as dynamic pressure and vehicle loads as well as safety margins. The designed trajectories are evaluated to analyse the terminal area flight phase and to assist in the development of the guidance program. The guidance method is evaluated utilising an program consisting of two parts, a real world simulator with high order models and a representation of the on-board guidance computer, the predictor, which uses low order models for computational efficiency. The guidance method is evaluated against a variety of off-nominal conditions to account for dispersions within the high order real world models and common errors experienced by re-entry vehicles. These off-nominal conditions include atmospheric disturbances, winds, aerodynamic, mass, navigation, steering and initial condition errors. The results of this study include a detailed analysis of the terminal area flight phase highlighting the major influences for vehicle and trajectory design. The study also confirms the applicability of the non-linear programming method utilising the vehicle steering parameters as a viable option for trajectory design and guidance. A comparison to other available results highlights the strengths and weaknesses of the proposed method. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1282342 / Thesis (Ph.D.)--School of Mechanical Engineering, 2007.

With new paradigms in software engineering such as Software Product Lines, scope of reuse is enlarged from implementation upto design, requirements, test-cases, etc. In this thesis an ontology-based approach is proposed as a solution to systematic requirement reuse problem in software product lines, and the approach is supported with a reuse automation tool. A case study is performed on the projects of an industrial software product line using hereby proposed solution and then based on the evaluated metrics it&rsquo / s reported that the content of requirements specifications documents can be prepared upto 80% by derivation of reusable requirements.

The purpose of this research was to study agricultural crop production 'decision support systems' as a means of transferring agricultural technology from research labs and plots to producers, extension specialists, agriculture service agencies, and scientists, on the Western Canadian Prairies. A 'decision support system' is a computer program that analyses problems spanning several knowledge or problem areas producing results that aid the management decision-making process. The primary objective was to develop a computer application program that would fulfill the farm manager's decision support needs and be "open" to future enhancements. This interdisciplinary study has a strong agricultural presence in the application context of the resultant computerized agricultural decision support system, with agronomics being the foundation on which the system was built, and computer science being the toolbox used to build it. Farm Smart 2000 is the resultant decision support system, providing "single-window" access to three different tiers of decision support utilizing the Internet, ' expert systems' and integrated multiple heterogeneous 'reusable agents' in a cooperative problem-solving environment. An ' expert system' is a computer program that solves complicated problems, within a specific knowledge or problem area, that would otherwise require human expertise. Expert systems integrated with each other within a decision support system are called 'agents. Reusable agents' are modular computer programs (e.g. expert systems) which can be used in more than one computer application with little or no modification. Farm Smart 2000 provides support for most management aspects of crop production including variety selection, crop rotations, weed management, disease management, residue management, harvesting, soil conservation, and economics, for the crops of wheat, canola, barley, peas, and flax. Tier-3, the most sophisticated level of Farm Smart 2000, is the focus of this dissertation and utilizes multiple reusable agents, integrating them such that they cooperate together to solve complex interrelated crop production problems. A Global Control Expert achieves the required communication and coordination among the agents resulting in an "open system", enabling Farm Smart 2000 to extend its problem-solving capabilities by integrating additional agents and knowledge, without system re-engineering, thereby remaining an ongoing technology transfer vehicle.