Case Study: Cooling Channels for Material Testing Applications Using Laser Powder Bed Fusion

Additive Manufacturing continues to gain a reputation as a key technology that will have a major impact on all aspects of mechanical engineering. The United States Air Force’s (USAF) Air Force Institute of Technology (AFIT), based in Dayton, Ohio, has expanded its AM-focused education and R&D capabilities with the purchase of a Laser Powder Bed Fusion system from Germany’s Concept Laser

Scaleup of mild gasification to be a process development. Quarterly report, February 1995--May 1995

The work performed during the Fourteenth quarterly reporting period (February 21 through May 20, 1995) on the research program, {open_quotes}Scale-Up of Mild Gasification to a Process Development Unit{close_quotes} is presented in this report. The overall objective of this project is to develop the IGT Mild-Gasification (MILDGAS) process for near-term commercialization. The specific objectives of the program are to: (1) design, construct, and operate a 24-tons/day adiabatic process development unit (PDU) to obtain process performance data suitable for further design scaleup; (2) obtain large batches of coal-derived co-products for industrial evaluation; (3) prepare a detailed design of a demonstration unit; and (4) develop technical and economic plans for commercialization of the MILDGAS process. The project team that is performing the initial phases of the PDU development are: Kerr-McGee Coal Corporation (K-M Coal), the Institute of Gas Technology (IGT), Bechtel Corporation (Bechtel), and Southern Illinois University at Carbondale (SIUC). The MILDGAS process is a continuous closed system for producing liquid and solid (char) co-products at mild operating conditions up to 50 psig and 1300{degrees}F. It is capable of processing a wide range of both eastern caking and western noncaking coals. The 1 ton/hr PDU facility that is to be constructed is comprised of a 2.5-ft ID adiabatic gasifier for the production of gases, coal liquids, and char; a three-stage condensation train to condense and store the liquid products; and coal feeding and char handling equipment. The facility will also incorporate support equipment for environmentally acceptable disposal of process waste. This quarter, the formal HAZOP review was completed and a report detailing action items for resolution by the parties responsible was prepared

Problematizing Choice: Responsible consumers and sceptical citizens

About the book: Governance, Consumers and Citizens is the first book to bring together a study of governance with consumption, examining the changing place of the consumer as citizen in recent trends in governance, the tensions between competing ideas and practices of consumerism and the active role consumers play in the construction and practice of governance. Radically pushing forward the debate on consumers and governance, this collection outlines new conceptions and posits new policy agendas. Bringing together international experts from political science, history, geography, social policy and media studies, this study shows how governance and consumption are intertwined in crucial aspects of public policy and contemporary politics

Status of the PICASSO Project

The Picasso project is a dark matter search experiment based on the superheated droplet technique. Preliminary runs performed at the Picasso Lab in Montreal have showed the suitability of this detection technique to the search for weakly interacting cold dark matter particles. In July 2002, a new phase of the project started. A batch of six 1-liter detectors with an active mass of approximately 40g was installed in a gallery of the SNO observatory in Sudbury, Ontario, Canada at a depth of 6,800 feet (2,070m). We give a status report on the new experimental setup, data analysis, and preliminary limits on spin-dependent neutralino interaction cross section.Comment: 3 pages, 2 figures. To appear in the Proceedings of the TAUP 2003 conference, 5-9 September, 2003, University of Washington, Seattle, US

A Model of Vertical Oligopolistic Competition

This paper develops a model of successive oligopolies with endogenous market entry, allowing for varying degrees of product differentiation and entry costs in both markets. Our analysis shows that the downstream conditions dominate the overall profitability of the two-tier structure while the upstream conditions mainly affect the distribution of profits. We compare the welfare effects of upstream versus downstream deregulation policies and show that the impact of deregulation may be overvalued when ignoring feedback effects from the other market. Furthermore, we analyze how different forms of vertical restraints influence the endogenous market structure and show when they are welfare enhancing

The Supercooling of a Nematic Liquid Crystal

We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the liquid is supercooled or compressed due to feedback from the density fluctuations which are freezing. We find similar results here for the longitudinal and various shear viscosities of the nematic. However, the two viscosities associated with the nematic director motion do not grow in any dramatic way; i.e.\ there is no apparent freezing of the director modes within this hydrodynamic formalism. Instead a glassy state of the nematic may arise from a ``random anisotropy" coupling of the director to the frozen density.Comment: Late

Full Flight Envelope Direct Thrust Measurement on a Supersonic Aircraft

Direct thrust measurement using strain gages offers advantages over analytically-based thrust calculation methods. For flight test applications, the direct measurement method typically uses a simpler sensor arrangement and minimal data processing compared to analytical techniques, which normally require costly engine modeling and multisensor arrangements throughout the engine. Conversely, direct thrust measurement has historically produced less than desirable accuracy because of difficulty in mounting and calibrating the strain gages and the inability to account for secondary forces that influence the thrust reading at the engine mounts. Consequently, the strain-gage technique has normally been used for simple engine arrangements and primarily in the subsonic speed range. This paper presents the results of a strain gage-based direct thrust-measurement technique developed by the NASA Dryden Flight Research Center and successfully applied to the full flight envelope of an F-15 aircraft powered by two F100-PW-229 turbofan engines. Measurements have been obtained at quasi-steady-state operating conditions at maximum non-augmented and maximum augmented power throughout the altitude range of the vehicle and to a maximum speed of Mach 2.0 and are compared against results from two analytically-based thrust calculation methods. The strain-gage installation and calibration processes are also described

Topological Defects and Interactions in Nematic Emulsions

Inverse nematic emulsions in which surfactant-coated water droplets are dispersed in a nematic host fluid have distinctive properties that set them apart from dispersions of two isotropic fluids or of nematic droplets in an isotropic fluid. We present a comprehensive theoretical study of the distortions produced in the nematic host by the dispersed droplets and of solvent mediated dipolar interactions between droplets that lead to their experimentally observed chaining. A single droplet in a nematic host acts like a macroscopic hedgehog defect. Global boundary conditions force the nucleation of compensating topological defects in the nematic host. Using variational techniques, we show that in the lowest energy configuration, a single water droplet draws a single hedgehog out of the nematic host to form a tightly bound dipole. Configurations in which the water droplet is encircled by a disclination ring have higher energy. The droplet-dipole induces distortions in the nematic host that lead to an effective dipole-dipole interaction between droplets and hence to chaining.Comment: 17 double column pages prepared by RevTex, 15 eps figures included in text, 2 gif figures for Fig. 1