Rule-based Verification of a Geometric Design using the Codex Framework

The definition of requirements is an important step of the aircraft design process. Usually, experts of different domains are involved in this multi-disciplinary process. Hence, knowledge from the different domains has to be efficiently shared and integrated. Supporting this process is the aim of the Codex (COllaborative DEsign and eXploration) framework, which is a Knowledge-Based Engineering (KBE) system currently being developed at the German Aerospace center (DLR). The design process results in the aircraft geometry determination which can be challenging for some components, subsystems or even new designs. To support this engineering task, this paper presents the codex-geometry module for geometry modelling using semantic web technologies within the Codex KBE framework. User-defined rules are used to express geometric requirements and analysis functions, which are automatically executed in order to verify and evaluate a geometric design. The presented approach is demonstrated by the example use case of a conventional fuel system model including pipe systems and fuel pumps

Modularity of the MIT Pebble Bed Reactor for use by the commercial power industry

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008."May 2008."Includes bibliographical references (leaves 112-113).The Modular Pebble Bed Reactor is a small high temperature helium cooled reactor that is being considered for both electric power and hydrogen production. Pebble bed reactors are being developed in South Africa, China and the US. To make smaller 120 Mwe reactors economically competitive with larger 1500 Mwe traditional light water reactors changes in the way these plants are built are needed. Economies of production need to be sufficiently large to compete with economies of scale. MIT (Berte) has been working on developing a modular design and construction strategy for several years. This thesis builds on that work by demonstrating the technical feasibility of implementing the modularity approaches previously developed. The MIT approach uses "space frames" containing all the components, piping, valves and needed cables, instrumentation in a specified volume. These space frames are built in a factory to assure high quality in manufacture. They are then shipped by train or truck to the site and assembled "lego" style. It is expected that with the improved quality in the factory setting, and rapid assembly at the site that the total time and cost of construction of the plant will be greatly reduced (Kadak). To make this process work, it is vitally important to assure that when the space frames and internal components are manufactured, they are done to rigid tolerances to assure line up when assembled in the field. By using many advanced three dimensional measurement technologies, including the use of digital photography, lasers, and photogrammetry, companies are now capable of fabricating pieces to extremely precise specifications at a relatively affordable cost. This thesis evaluates the feasibility of manufacture of space frames and internal components to the required tolerances, the accuracy control needed and how the plant can be assembled with details of each space frame interfaces.(cont.) A global reference system was determined and a basic plant map for space frame placement developed. Deviations from exact placement from this map due to tolerance allowances were factored in and methods and techniques for overcoming any variations was developed. In order to enable each frame and it's respective components to be accurately fabricated to ensure interfacing parts will mate, a local coordinate system was developed for each frame and used to describe the exact location of the required interfaces for each specific frame. Crucial concepts of accuracy control and "best fit" are outlined and incorporated. Based on independent verification of the processes and the design proposed, this modularity approach appears to be feasible. A comparative economic analysis was also performed to assess the potential cost savings of the modularity approach compared to traditional "stick build" approaches presently being used in nuclear construction. Manhour, learning curve and overall cost savings of over 30 % can be expected which suggests that if modularity approaches as those proposed are used, smaller reactors can compete with larger economies of scale plants.by Jaime E. Hanlon-Hyssong.S.M

Parallel three-dimensional acoustic and elastic wave simulation methods with applications in nondestructive evaluation

In this dissertation, we present two parallelized 3D simulation techniques for three-dimensional acoustic and elastic wave propagation based on the finite integration technique. We demonstrate their usefulness in solving real-world problems with examples in the three very different areas of nondestructive evaluation, medical imaging, and security screening. More precisely, these include concealed weapons detection, periodontal ultrasography, and guided wave inspection of complex piping systems. We have employed these simulation methods to study complex wave phenomena and to develop and test a variety of signal processing and hardware configurations. Simulation results are compared to experimental measurements to confirm the accuracy of the parallel simulation methods

2009 Government and Industry Pipeline R&D Forum Report

Nine government and industry organizations via a steering committee organized, planned and executed this forum. The forum brought together approximately 215 representatives from Federal, State and foreign government offices along with domestic and foreign natural gas and hazardous liquid pipeline operators. The forum’s goals included identifying key challenges facing industry and government, sharing information on current research efforts, and identifying research that can help to meet the challenges

Design requirements for prefabricated mechanical and plumbing systems

Prefabrication has been shown to increase the productivity and minimize waste in the field of construction more than 30 years ago. Regardless of these identified benefits of prefabrication, its implementation on the mechanical and plumbing disciplines remains largely absent in the Finnish construction industry. The aim of this thesis is to identify the technical design requirements needing fulfillment for prefabrication of mechanical and plumbing systems. The thesis also contains a tentative solution to how the identified design requirements can be fulfilled. The design science research methodology is utilized in this thesis to develop a practical solution for the research problem. The thesis consists of two case studies and a modeling experiment. The two case studies involved evaluation of operators utilizing prefabricated mechanical and plumbing systems and evaluating their design requirements. Based on the identified requirements utilized by the operators, a modeling experiment tested whether the identified requirements can be fulfilled with established design software. This study has identified three concepts enabling prefabrication of mechanical and plumbing systems and demonstrated that the requirements can be achieved with established design software. The identified concepts found in this study enabled the proposition of a design science artifact, that enables the design of prefabricated mechanical and plumbing systems through a certain workflow. The artifact was furthermore validated with the descriptive validation procedure. The proposed artifact indicate that prefabrication of mechanical and plumbing systems is possible through implementation of new workflows in the design process