12,891 research outputs found
Research study on materials processing in space experiment number M512
Conclusions of the team of specialists can be generalized as: (1) Brazing and welding of metal structures in an orbital near zero gravity condition are quite feasible. (2) Design of joints for fabrication in zero gravity will place less emphasis on the tolerances and proximity of the adjacent structures than on the quantity of liquid metal available. (3) Brazing of metallic joints has many advantages over electron beam welding for practical reasons: simplicity, launch weight, development costs, joint design tolerances, remotization, etc. (4) No evidence of different physical or mechanical properties of liquid metals in zero gravity was observed. However, many differences in liquid behavior were observed. Many of these effects have been called adhesion-cohesion phenomena
Research study on materials processing in space experiment number M512
Adhesion of the melted metals to the adjacent solid metals, and cohesion of the liquid metal to itself appeared to be equally as strong in zero gravity as on earth. Similar cut edge bead periodicity in cut thin plate, and similar periodic chevron patterns in full penetration welds were seen. The most significant practical result is that the design of braze joints for near zero gravity can be very tolerant of dimensional gaps in the joint. This conclusion is based on a comparison of narrow, wide and variable gap widths. Brazing is very practical as a joining or repairing technique for metal structures at zero gravity. The operation of the hardware developed to locate successive small (0.6 cm) diameter cylinders in the focus of the battery powered EB unit, melt the various metal specimens and deploy some liquid metal drops to drift in space, was generally successful. However, the sphericity and surface roughness were far from those of ball bearings
A project and competition to design and build a simple heat exchanger
To address a declining interest in process engineering, a project to design and build a compact heat exchanger was initiated in the second year of a four-year, multidisciplinary degree programme in biotechnology. The heat exchangers had a double-pipe configuration and employed plastic outer pipes and copper inner pipes of various diameters. Designs produced ranged from coiled inner pipes to various multi-pass arrangements and were assessed on the basis of heat transfer achieved per unit mean temperature difference per unit cost. The project, which also formed the basis of a competition, was very well received by students and gave them hands-on experience of engineering design and construction, as well as team work, problem solving, engineering drawing and the use of simple tools. Based on the success of this project, a similar problem based learning approach will be initiated in the third year of the same degree programme and will focus on bioethanol production
Commissioning the LHCb VErtex LOcator (VELO)
The LHCb VErtex LOcator (VELO) is designed to reconstruct primary and secondary vertices in b-hadron decays. It is a silicon microstrip detector situated closest to the interaction region. It provides fast tracking information to the trigger system. The design of the detector and the commissioning of its various sub-components are described here
Antitrust—Clayton Act—Application of Section 7 to Bank Mergers.—United States v. Philadelphia Nat. Bank
Space shuttle orbit maneuvering engine reusable thrust chamber program
Tests were conducted on the regenerative cooled thrust chamber of the space shuttle orbit maneuvering engine. The conditions for the tests and the durations obtained are presented. The tests demonstrated thrust chamber operation over the nominal ranges of chamber pressure mixture ratio. Variations in auxiliary film coolant flowrate were also demonstrated. High pressure tests were conducted to demonstrate the thrust chamber operation at conditions approaching the design chamber pressure for the derivative space tug application
Third sector organizations and earthquake recovery planning in Christchurch, New Zealand
On September 4, 2010, an earthquake struck rural Canterbury and the most deadly of over 2,000 aftershocks devastated the Christchurch Central Business District on February 22, 2011 (Ardagh et al. 2012). Questions have arisen regarding population dynamics (Love 2011), marginalized groups, health and social care, and overall recovery efforts. Addressing some of these concerns are various non-profit, non-governmental, and faith based groups, collectively referred to as Third Sector Organizations (TSOs). By providing an alternative to and back-stopping government and private health and social services, TSOs are able to build resiliency following a natural disaster, and are especially able to identify and address unmet needs within their target audiences and maintain a sense of community within their operating areas. The nature of community recovery, also changes the role of TSOs in formal and grassroots efforts over time. In New Zealand, TSOs have shared community health burdens with government and private practices since the 1990s (Larner and Craig 2005) and have championed healthcare policy measures for ethnic minorities (Came 2014). Nevertheless, the earthquakes have presented challenges to TSOs. An inventory of 92 TSOs four months after the earthquakes, 106 one year after, and 454 two years after by Carlton and Vallance (2013) shows that although many TSOs have emerged to address earthquake related issues, other TSOs may have been unable to re-establish themselves outside areas with earthquake damage found to be too severe to inhabit by the Canterbury Earthquake Recovery Authority (CERA). Others reported “burn-out” and 52 were inactive or closed because of shifting needs during recovery. This research identifies shared experiences across the third sector in Canterbury to illuminate shifting roles in mid to long-term earthquake recovery
Effect of patch resolution and raster cell size on selected landscape metrics applied at Lubrecht Experimental Forest
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