678 research outputs found

    Smooth and polyhedral approximation in Banach spaces

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    We show that norms on certain Banach spaces XX can be approximated uniformly, and with arbitrary precision, on bounded subsets of XX by CC^{\infty} smooth norms and polyhedral norms. In particular, we show that this holds for any equivalent norm on c0(Γ)c_0(\Gamma), where Γ\Gamma is an arbitrary set. We also give a necessary condition for the existence of a polyhedral norm on a weakly compactly generated Banach space, which extends a well-known result of Fonf.Comment: 12 page

    Environmental analysis of hardwood sawmills : a segment of the hardwood forest products industry

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    Hardwood sawmills represent a primary manufacturing segment of the hardwood forest products industry. Each mill exists within and is dependent on its external business environment. The external environment is where the sawmill obtains inputs, deliver outputs and acquires information. The purpose of this research was to explore important factors and recent changes in the hardwood sawmill external environment. The external business environment cannot be studied directly. It can, however, be viewed indirectly with the help of managerial perceptions relevant to the external environment and other pertinent information. The objectives of the study were to: 1) Identify the sectors in the operating and general sections of the external environment which are important as perceived by hardwood sawmill managers, 2) Identify which of those sectors are perceived by managers as variable, and 3) Document changes within the mills. This paper presents the results of an exploratory study of the hardwood sawmill external environment in the language of general systems theory. The study consisted of a review of 879 journal articles and telephone interviews with 21 sawmill managers. A description of the external environment is developed and a typology is advanced

    Evaluating strategic project and portfolio performance

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    To assess performance at the portfolio level, it is vital to measure the performance of individual projects and consolidate the measurements in a mathematically meaningful way that reflects the strategic importance of the member projects. Beyond the traditional metrics, obvious questions are how to: (1) derive project strategic performance using traditional performance measurements, (2) synthesise individual project measurements into meaningful strategic performance measurements at the portfolio level, and (3) assess current project and portfolio strategic performance with respect to continued expectation of achieving strategic objectives as they progress through implementation. This article proposes solutions for the first two questions and suggests a means of approaching the third.

    Directed Energy For Relativistic Propulsion and Interstellar Communications

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    An orbital planetary defense system that is also capable of beamed power propulsion allows mildly relativistic spacecraft speeds using existing technologies. While designed to heat the surface of potentially hazardous objects to the evaporation point to mitigate asteroid threats the system is inherently multi-functional with one mode being relativistic beamed spacecraft propulsion. The system is called DE-STAR for Directed Energy Solar Targeting of Asteroids and exploRation. DE-STAR is a proposed orbital platform that is a modular phased array of lasers, powered by the sun. Modular design allows for incremental development, test and initial deployment, lowering cost, minimizing risk and allowing for technological co-development, leading eventually to an orbiting structure that could be erected in stages. The main objective of DE-STAR would be to use the focused directed energy to raise the surface spot temperature of an asteroid to ~3,000 K, allowing direct evaporation of all known substances. The same system is also capable of propelling spacecraft to relativistic speeds, allowing rapid interplanetary travel and relativistic interstellar probes. Our baseline system is a DE-STAR 4, which is a 10 km square array that is capable of producing a 30 m diameter spot at a distance of 1 AU from the array. Such a system allows for engaging an asteroid that is beyond 1 AU from the DE-STAR 4. When used in its “photon rail gun mode”, a DE-STAR 4 would be capable of propelling a 1, 10, 102, 103, 104 kg spacecraft that is equipped with a 30 m diameter reflector to 1 AU in approximately 0.3, 1, 3, 10, 30 days, respectively, with speeds of about 4%, 1.2%, 0.4%, 0.15%, 0.05% the speed of light at 1 AU. With continued illumination to 3 AU the spacecraft, with a 30 m diameter reflector, would reach speeds √2 faster. A DE-STAR 4 could propel a 102 kg probe with 900 m diameter reflector to 2% the speed of light with continued illumination out to 30 AU, and ultimately to 3% the speed of light after which the spacecraft will coast. Such speeds far exceed the galactic escape velocity. Smaller systems are also extremely useful and can be built now. For example, a DE-STAR 1 (10 m size array) would be capable of evaporating space debris at 104 km (~diam. of Earth) while a DE-STAR 2 could divert volatile-laden asteroids 100 m in diameter by initiating engagement at ~0.01-0.5 AU. All sized systems can be used to propel varying sized systems for both testing and for interplanetary use. An extreme case is a wafe scale spacecraft (WaferSat) with a 1 m reflector that can achieve \u3e25%c in about 15 minutes. The phased array configuration is capable of creating multiple beams, so a single DE-STAR of sufficient size could engage several threats simultaneously or propelling several spacecraft. A DE-STAR could also provide power to ion propulsion systems, providing both a means of acceleration on the outbound leg, and deceleration for orbit insertion by rotating the spacecraft “ping-ponging” between two systems in either a photon rail gun mode or power ion engines. There are a number of other applications as well including SPS for down linking power to the Earth via millimeter or microwave. A larger system such as a DE-STAR 6 system could propel a 104 kg spacecraft to near the speed of light allowing for true interstellar travel. The same technology can also be used for extremely long range communications with continuous communication between Earth and the interstellar spacecraft. This technology also has direct implications for interstellar and intergalactic beaming allowing for SETI across the universe for civilizations that have mastered this technology. There are a number of other applications for the system. While decidedly futuristic in its outlook many of the core technologies now exist and small systems can be built to test the basic concepts as the technology improves. While there are enormous challenges to fully implementing this technology the opportunities enabled are truly revolutionary

    Space Applications Industrial Laser System (SAILS)

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    A program is underway to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. This workstation, called Space Applications Industrial Laser System (SAILS), will be capable of cutting and welding steel, aluminum, and Inconel alloys of the type planned for use in constructing the Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1996, will be constructed as three modules using standard Get-Away-Special (GAS) canisters. The first module holds the laser head and cooling system, while the second contains a high peak power electrical supply. The third module houses the materials processing workstation and the command and data acquisition subsystems. The laser head and workstation cansisters are linked by a fiber-optic cable to transmit the laser light. The team assembled to carry out this project includes Lumonics Industrial Products (laser), Tennessee Technological University (structural analysis and fabrication), Auburn University Center for Space Power (electrical engineering), University of Waterloo (low-g laser process consulting), and CSTAR/UTSI (data acquisition, control, software, integration, experiment design). This report describes the SAILS program and highlights recent activities undertaken at CSTAR

    Bonded design in the university: Faculty and information technology professionals bonding through participatory design

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    The participatory design approach, Bonded Design (BD), originally developed for use with intergenerational teams provides the framework for the Faculty IT Liaison Program, a project initiated in a large research university to encourage meaningful interaction between faculty and IT professional staff. BD was chosen for its adaptable methodology and its purpose in bringing together two disparate groups in the shared experience of a design team. Study findings indicate that the Bonded Design approach promotes deeper understandings and the generation of design ideas and innovations that might not be considered in a homogeneous peer environment

    Strategic Facilities Management Using Public and Private Funding for Energy Projects: A Case Study

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    The Alamo Community College District (ACCD) in San Antonio, Texas has a long history of participating in public and private sector loan programs for facilities energy projects. In its most recent experience, the District has demonstrated the value of these loans beyond simple kWh savings. In 2002, The District received 3.0millioninprivatesectorloansforprojectsincludingindoorlightingretrofits,coolingtowerupgrades,andContinuousCommissioning®.Documentedenergycostsavingsfromthisprojectexceededtheprojectedsavingssinceitscompletioninearly2005.Nownearlyadecadelater,ACCDisparticipatinginaStatefundedrevolvingloanprogramforenergyretrofitsestimatedat3.0 million in private sector loans for projects including indoor lighting retrofits, cooling tower upgrades, and Continuous Commissioning®. Documented energy cost savings from this project exceeded the projected savings since its completion in early 2005. Now nearly a decade later, ACCD is participating in a State-funded revolving loan program for energy retrofits estimated at 10 million. A wide range of projects are proposed, including indoor and outdoor lighting retrofits, central plant upgrades, solar thermal pool heating, enhanced retrofit commissioning and installation of water based thermal storage systems. In addition, existing campus load profile analysis uncovered utility rate change options that yielded instant savings. In total, over $1 million per year in cost savings and 4 megawatts of mitigated power generation capacity are projected due to these projects. This paper presents the details of the loan procurement process as part of a state program designed for building energy efficiency retrofit projects, and how ACCD is using available resources to strategically integrate short-term systems upgrades with long-term infrastructure, energy management, and sustainability goals

    Spatially nonrandom tree mortality and ingrowth maintain equilibrium pattern in an old-growth \u3ci\u3ePseudotsuga–Tsuga\u3c/i\u3e forest

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    Mortality processes in old-growth forests are generally assumed to be driven by gap-scale disturbance, with only a limited role ascribed to density-dependent mortality, but these assumptions are rarely tested with data sets incorporating repeated measurements. Using a 12-ha spatially explicit plot censused 13 years apart in an approximately 500-year-old Pseudotsuga–Tsuga forest, we demonstrate significant density-dependent mortality and spatially aggregated tree recruitment. However, the combined effect of these strongly nonrandom demographic processes was to maintain tree patterns in a state of dynamic equilibrium. Density-dependent mortality was most pronounced for the dominant latesuccessional species, Tsuga heterophylla. The long-lived, early-seral Pseudotsuga menziesii experienced an annual stem mortality rate of 0.84% and no new recruitment. Late-seral species Tsuga and Abies amabilis had nearly balanced demographic rates of ingrowth and mortality. The 2.34% mortality rate for Taxus brevifolia was higher than expected, notably less than ingrowth, and strongly affected by proximity to Tsuga. Large-diameter Tsuga structured both the regenerating conspecific and heterospecific cohorts with recruitment of Tsuga and Abies unlikely in neighborhoods crowded with large-diameter competitors (P , 0.001). Densitydependent competitive interactions strongly shape forest communities even five centuries after stand initiation, underscoring the dynamic nature of even equilibrial old-growth forests

    Stochastic Assembly of Bacteria in Microwell Arrays Reveals the Importance of Confinement in Community Development

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    Citation: Hansen, R. H., Timm, A. C., Timm, C. M., Bible, A. N., Morrell-Falvey, J. L., Pelletier, D. A., . . . Retterer, S. T. (2016). Stochastic Assembly of Bacteria in Microwell Arrays Reveals the Importance of Confinement in Community Development. Plos One, 11(5), 18. doi:10.1371/journal.pone.0155080The structure and function of microbial communities is deeply influenced by the physical and chemical architecture of the local microenvironment and the abundance of its community members. The complexity of this natural parameter space has made characterization of the key drivers of community development difficult. In order to facilitate these characterizations, we have developed a microwell platform designed to screen microbial growth and interactions across a wide variety of physical and initial conditions. Assembly of microbial communities into microwells was achieved using a novel biofabrication method that exploits well feature sizes for control of innoculum levels. Wells with incrementally smaller size features created populations with increasingly larger variations in inoculum levels. This allowed for reproducible growth measurement in large (20 mu m diameter) wells, and screening for favorable growth conditions in small (5, 10 mu m diameter) wells. We demonstrate the utility of this approach for screening and discovery using 5 mu m wells to assemble P. aeruginosa colonies across a broad distribution of innoculum levels, and identify those conditions that promote the highest probability of survivial and growth under spatial confinement. Multi-member community assembly was also characterized to demonstrate the broad potential of this platform for studying the role of member abundance on microbial competition, mutualism and community succession

    Directed Energy Active Illumination for Near-Earth Object Detection

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    On 15 February 2013, a previously unknown ~20 m asteroid struck Earth near Chelyabinsk, Russia, releasing kinetic energy equivalent to ~570 kt TNT. Detecting objects like the Chelyabinsk impactor that are orbiting near Earth is a difficult task, in part because such objects spend much of their own orbits in the direction of the Sun when viewed from Earth. Efforts aimed at protecting Earth from future impacts will rely heavily on continued discovery. Ground-based optical observatory networks and Earth-orbiting spacecraft with infrared sensors have dramatically increased the pace of discovery. Still, less than 5% of near-Earth objects (NEOs) 100 m/~100 Mt TNT have been identified, and the proportion of known objects decreases rapidly for smaller sizes. Low emissivity of some objects also makes detection by passive sensors difficult. A proposed orbiting laser phased array directed energy system could be used for active illumination of NEOs, enhancing discovery particularly for smaller and lower emissivity objects. Laser fiber amplifiers emit very narrow-band energy, simplifying detection. Results of simulated illumination scenarios are presented based on an orbiting emitter array with specified characteristics. Simulations indicate that return signals from small and low emissivity objects is strong enough to detect. The possibility for both directed and full sky blind surveys is discussed, and the resulting diameter and mass limits for objects in different observational scenarios. The ability to determine both position and speed of detected objects is also discussed
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