Parabolic Dish Concentrator (PDC-1)

The design, construction, and installation of the Parabolic Dish Concentrator, Type 1 (PDC-1) has been one of the most significant JPL concentrator projects because of the knowledge gained about this type of concentrator and the development of design, testing, and analysis procedures which are applicable to all solar concentrator projects. The need for these procedures was more clearly understood during the testing period which started with the prototype panel evaluation and ended with the performance characterization of the completed concentrator. For each phase of the test program, practical test procedures were required and these procedures defined the mathematical analysis which was essential for successful concentrator development. The concentrator performance appears to be limited only by the distortions resulting from thermal gradients through the reflecting panels. Simple optical testing can be extremely effective, but comprehensive mechanical and optical analysis is essential for cost effective solar concentrator development

Emerging issues in sustainable industrial design practice : implications for designers, manufacturers and educators

University of Technology, Sydney. Faculty of Design, Architecture and Building.Industrial designers have been addressing issues of sustainability for many years with varying levels of intensity and mixed results. Since the 1970s, practitioners and educators in the field of product design have demonstrated an appreciation of issues related to the life cycles of products, the conservation of energy and natural resources , and the recycling of materials, and this awareness has been reflected in approaches to professional practice and in the academic curricula for industrial design students. With the advent of the 21st century, a number of emerging sustainability issues, associated largely with the implications of global warming and increasing greenhouse gas emissions , have posed new challenges for governments, manufacturers, and industrial design practitioners and educators. These issues include those identified from the available literature relate to Environmental Management Systems, Increases in Off-shore Manufacturing, Sustainable Procurement, Developments in E-commerce, 'Green' Marketing, Developments in waste management and recycling, Challenges for Environmental Legislators, After-sales Product Support, Developments in Ecodesign Tools, The Opportunities and Challenges of Rapid Prototyping, Emerging Sustainability Issues for Educators. For industrial designers, the challenges arising from the emerging issues relate not only to their desire to be ethical, but also to their need to remain competitive. The focus of this thesis is upon the sustainability issues that have emerged in the early years of the 21st century. It looks first at the foundations of a sustainability consciousness and some traditional attitudes and approaches to sustainability that have been adopted by industrial design stakeholders since the 1970s. It draws upon the work of James (2001) and others to develop a theoretical framework on sustainability issues that are emerging in the early 21st century. This framework is then used to underpin an investigation conducted among industrial designers and manufacturers on sustainability issues that have emerged since approximately 2000, and their implications for the sector. Following identification and analysis of the emerging issues, a number of strategies are proposed for industrial design stakeholders to meet the challenges posed by the emerging sustainability issues. These include strategies for practitioners and manufacturers to promotes sustainability while remaining competitive, desirable changes to the curriculum of industrial design courses, and the revision and updating of out-dated environmental legislation

Trumpet Slices in Kerr Spacetimes

We introduce a new time-independent family of analytical coordinate systems for the Kerr spacetime representing rotating black holes. We also propose a (2+1)+1 formalism for the characterization of trumpet geometries. Applying this formalism to our new family of coordinate systems we identify, for the first time, analytical and stationary trumpet slices for general rotating black holes, even for charged black holes in the presence of a cosmological constant. We present results for metric functions in this slicing and analyze the geometry of the rotating trumpet surface.Comment: 5 pages, 2 figures; version published in PR

Trumpet slices of the Schwarzschild-Tangherlini spacetime

We study families of time-independent maximal and 1+log foliations of the Schwarzschild-Tangherlini spacetime, the spherically-symmetric vacuum black hole solution in D spacetime dimensions, for D >= 4. We identify special members of these families for which the spatial slices display a trumpet geometry. Using a generalization of the 1+log slicing condition that is parametrized by a constant n we recover the results of Nakao, Abe, Yoshino and Shibata in the limit of maximal slicing. We also construct a numerical code that evolves the BSSN equations for D=5 in spherical symmetry using moving-puncture coordinates, and demonstrate that these simulations settle down to the trumpet solutions.Comment: 11 pages, 6 figures, submitted to PR

Relevancy of Pulsed Electroacoustic Measurements for Investigating Spacecraft Charging

The magnitude and spatial distribution of charge embedded in dielectric materials and the evolution of the charge distributions with time are paramount for the understanding and mitigation of spacecraft charging. Spacecraft materials are charged primarily by incident fluxes of low-energy electrons, with electron fluxes in the 10–50 keV range often responsible for the most deleterious arcing effects. While the pulsed electroacoustic (PEA) method can provide sensitive nondestructive measurements of the internal charge distribution in insulating materials, it has often been limited for spacecraft charging applications by typical spatial resolutions of ≤ 10 μm , with a 10- μm range of electrons in common spacecraft materials (e.g., polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), low-density polyethylene (LDPE), or SiO2) at incident energies from ~ 20 to ~ 40 keV. A series of PEA tests over a range of incident electron energies were devised to investigate the relevance of the PEA method for typical spacecraft charging applications. Thin-film samples of vacuum-baked PEEK were irradiated with 10–80-keV monoenergetic electron beams. PEA measurements of deposited charge profiles determined the peak positions and magnitude of deposited charge. These were used to establish the minimum incident energies for which PEA measurements provided meaningful results and thus to characterize the merits of PEA measurements over energy ranges of relevancy to spacecraft charging issues

A Simple Method for Determining Shallow Charge Distributions in Dielectrics Via Pulsed Electroacoustic Measurements

The understanding of charge dynamics in dielectric materials is paramount in mitigating electrostatic discharge events for spacecraft. The most critical spacecraft charging events are found to result from incident electrons in the energy range of 10 keV to 50 keV. The charge embedded in dielectric materials in this energy range are deposited a distance into the material on the order of a few to tens of microns. One way to measure and understand the deposited charge is via pulsed electroacoustic measurements (PEA). However, the typical PEA spatial resolution of ~ 10 μm is not sufficient to resolve or discern charge deposited at the lower end of this incident electron energy range, where deposited charge distributions are obscured by the superposition of the signal originating from induced mirror charge on the electrode of the pulsed electroacoustic system. A simple method is proposed and demonstrated in which reference measurements from a pristine sample are used to separate the effect of the induced mirror charge from the measured embedded charge to obtain a more accurate determination of the deposited charge distribution

Charge Dynamics in Highly Insulating Space Craft Materials

We present a preliminary report on the theoretical and experimental study of transport models in highly insulating materials. The report is developed in four sections; first we give background on the nature of the problems in space craft charging, the contributions and connections made by the Utah State material physics group. Second we discuss the density of states to explore the connections between material composition and the microscopic and macroscopic transport equations. Third from Maxwell’s equations we present an overview of the transport equations. Finally we present preliminary results using experimental data on KaptonTM, the transport equations and relevant expressions for the density of states

Resistivity as Dynamic Behavior in Low Density Polyethylene

Bridging the gap between theoretical calculations and experimental data has been the focus of much of the research into the electrical behavior of insulating polymers. Low density polyethylene is the standard test material used in both experimental work and numerical calculations. Resistivity measurements provide more than an absolute value for technical use; they also provide insight into the nature of active charge carriers and trapping behavior within LDPE