12,408 research outputs found

    Technology review of flight crucial flight controls

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    The results of a technology survey in flight crucial flight controls conducted as a data base for planning future research and technology programs are provided. Free world countries were surveyed with primary emphasis on the United States and Western Europe because that is where the most advanced technology resides. The survey includes major contemporary systems on operational aircraft, R&D flight programs, advanced aircraft developments, and major research and technology programs. The survey was not intended to be an in-depth treatment of the technology elements, but rather a study of major trends in systems level technology. The information was collected from open literature, personal communications and a tour of several companies, government organizations and research laboratories in the United States, United Kingdom, France, and the Federal Republic of Germany

    Life-cycle assessments in the South African water sector: A review and future challenges

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    This paper reviews South African water sector life-cycle assessments (LCAs) and develops a position on how this tool could be strategically employed in the future. It summarises the studies undertaken, highlighting the significant findings and the lessons learnt. In addition, international trends and their implications for the local LCA community and the water sector are presented and strategic recommendations for the future are included. The various LCA studies undertaken in the local water industry have shown that the abstraction of water from the environment (in a country where it is a limited resource) and the use of energy for treating and pumping water and wastewater have the highest environmental burdens. These studies have also demonstrated the versatility of LCA as a decision-making tool in the water industry by comparing technologies and scenarios, identifying improvement opportunities and prioritising interventions and their consequences in complex water systems. Recent international work has confirmed the usefulness of a life-cycle approach also for water footprinting. Therefore, in South Africa it is important to promote the use of LCAs for the water sector in order to improve efficiency of processes and systems, but also to promote life-cycle based water footprinting and to include differentiated water consumption data into life-cycle inventories to make more efficient use of water as a resource.Keywords: life cycle assessments, water footprinting, urban water system

    Technology review of flight crucial flight control systems (application of optical technology)

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    The survey covers the various optical elements that are considered in a fly-by-light flight control system including optical sensors and transducers, optical data links, so-called optical actuators, and optical/electro-optical processing. It also addresses airframe installation, maintenance, and repair issues. Rather than an in-depth treatment of optical technology, the survey concentrates on technology readiness and the potential advantages/disadvantages of applying the technology. The information was assembled from open literature, personal interviews, and responses to a questionnaire distributed specifically for this survey. Not all of the information obtained was consistent, particularly with respect to technology readiness. The synthesis of information into the perception of the state-of-technology is presented

    Mechanical strength and tribological behavior of ion-beam deposited boron nitride films on non-metallic substrates

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    An investigation was conducted to examine the mechanical strength and tribological properties of boron nitride (BN) films ion-beam deposited on silicon (Si), fused silica (SiO2), gallium arsenide (GaAs), and indium phosphide (InP) substrates in sliding contact with a diamond pin under a load. The results of the investigation indicate that BN films on nonmetallic substrates, like metal films on metallic substrates, deform elastically and plastically in the interfacial region when in contact with a diamond pin. However, unlike metal films and substrates, BN films on nonmetallic substrates can fracture when they are critically loaded. Not only does the yield pressure (hardness) of Si and SiO2 substrates increase by a factor of 2 in the presence of a BN film, but the critical load needed to fracture increases as well. The presence of films on the brittle substrates can arrest crack formation. The BN film reduces adhesion and friction in the sliding contact. BN adheres to Si and SiO2 and forms a good quality film, while it adheres poorly to GaAs and InP. The interfacial adhesive strengths were 1 GPa for a BN film on Si and appreciably higher than 1 GPa for a BN film on SiO2

    Differential negative reinforcement of other behavior to increase compliance with wearing an anti-strip suit

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    Using a changing-criterion design, we replicated and extended a study (Cook, Rapp, & Schulze, 2015) on differential negative reinforcement of other behavior (DNRO). More specifically, educational assistants implemented DNRO to teach a 12-year-old boy with autism spectrum disorder to comply with wearing an anti-strip suit to prevent inappropriate fecal behavior in a school setting. The duration for which the participant wore the suit systematically increased from 2 s at the start of treatment to the entire duration of the school day at the termination of the study. Moreover, these effects were generalized to a new school with novel staff and persisted for more than a year. These findings replicate prior research on DNRO and further support the use of the intervention to increase compliance with wearing protective items, or medical devices, in practical settings

    Tribology: The Story of Lubrication and Wear

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    Topics addressed include: lubrication and design of high speed rolling element bearings, high speed gears, and traction drives

    A bargaining and property rights perspective on the Belt and Road Initiative: Cases from the Italian port system

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    Infrastructural assets are vital for a country’s economic and social development. Governments typically provide the regulation and administration of these assets, while multinational enterprises (MNEs) develop, construct, finance, and operate them. The Belt and Road Initiative (BRI) promises infrastructure projects that deliver economic and social benefit for both the host country and the MNE, however, the foreign market entry activities of Chinese MNEs in infrastructure projects might not always be successful. By bridging the bargaining power literature with the economics of property rights perspective, we examine how and why host-country actors at different governance levels influence foreign direct investment. Using a comparative case study approach, we interrogate four attempts by Chinese firms to negotiate access to Italian ports. In particular, we show that for a BRI port investment to take place, there has to be an alignment between the various actors of the property rights nexus regarding the allocation of rights. Chinese investors need to understand the bargaining position and property rights of actors across multiple levels, across space, and be mindful of changes over time when negotiating an infrastructure investment. Host-country governments need to have a clear port infrastructure strategy to avoid wasting resources in lengthy negotiations and useless infrastructure

    Quark mass uncertainties revive KSVZ axion dark matter

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    The Kaplan-Manohar ambiguity in light quark masses allows for a larger uncertainty in the ratio of up to down quark masses than naive estimates from the chiral Lagrangian would indicate. We show that it allows for a relaxation of experimental bounds on the QCD axion, specifically KSVZ axions in the 23μ2-3 \mueV mass range composing 100% of the galactic dark matter halo can evade the experimental limits placed by the ADMX collaboration.Comment: 9 pages, 5 figure

    Observing Spontaneous Strong Parity Violation in Heavy-Ion Collisions

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    We discuss the problem of observing spontaneous parity and CP violation in collision systems. We discuss and propose observables which may be used in heavy-ion collisions to observe such violations, as well as event-by-event methods to analyze the data. Finally, we discuss simple monte-carlo models of these CP violating effects which we have used to develop our techniques and from which we derive rough estimates of sensitivities to signals which may be seen at RHIC

    Optical Follow-up of New SMC Wing Be/X-ray Binaries

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    We investigate the optical counterparts of recently discovered Be/X-ray binaries in the Small Magellanic Cloud. In total four sources, SXP101, SXP700, SXP348 and SXP65.8 were detected during the Chandra Survey of the Wing of the SMC. SXP700 and SXP65.8 were previously unknown. Many optical ground based telescopes have been utilised in the optical follow-up, providing coverage in both the red and blue bands. This has led to the classification of all of the counterparts as Be stars and confirms that three lie within the Galactic spectral distribution of known Be/X-ray binaries. SXP101 lies outside this distribution becoming the latest spectral type known. Monitoring of the Halpha emission line suggests that all the sources bar SXP700 have highly variable circumstellar disks, possibly a result of their comparatively short orbital periods. Phase resolved X-ray spectroscopy has also been performed on SXP65.8, revealing that the emission is indeed harder during the passage of the X-ray beam through the line of sight.Comment: 9 pages, 9 figures, 2 tables, accepted for publication in MNRA
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