58,211 research outputs found
The MVA Priority Approximation
A Mean Value Analysis (MVA) approximation is presented for computing the average performance measures of closed-, open-, and mixed-type multiclass queuing networks containing Preemptive Resume (PR) and nonpreemptive Head-Of-Line (HOL) priority service centers. The approximation has essentially the same storage and computational requirements as MVA, thus allowing computationally efficient solutions of large priority queuing networks. The accuracy of the MVA approximation is systematically investigated and presented. It is shown that the approximation can compute the average performance measures of priority networks to within an accuracy of 5 percent for a large range of network parameter values. Accuracy of the method is shown to be superior to that of Sevcik's shadow approximation
High-speed civil transport flight- and propulsion-control technological issues
Technology advances required in the flight and propulsion control system disciplines to develop a high speed civil transport (HSCT) are identified. The mission and requirements of the transport and major flight and propulsion control technology issues are discussed. Each issue is ranked and, for each issue, a plan for technology readiness is given. Certain features are unique and dominate control system design. These features include the high temperature environment, large flexible aircraft, control-configured empennage, minimizing control margins, and high availability and excellent maintainability. The failure to resolve most high-priority issues can prevent the transport from achieving its goals. The flow-time for hardware may require stimulus, since market forces may be insufficient to ensure timely production. Flight and propulsion control technology will contribute to takeoff gross weight reduction. Similar technology advances are necessary also to ensure flight safety for the transport. The certification basis of the HSCT must be negotiated between airplane manufacturers and government regulators. Efficient, quality design of the transport will require an integrated set of design tools that support the entire engineering design team
Recommended from our members
A partnership-based, whole-watershed approach to climate adaptation in Acadia National Park
Changes in climate and associated changes in seasonality, invasive plants and insects, and visitation are stressing ecosystems and infrastructure in Acadia National Park. Over the past five years, park staff and partners have begun taking an interdisciplinary, partnership-based approach to assessing baseline conditions, identifying stresses, developing climate change scenarios, and restoring the ecological and cultural integrity and resilience of whole watersheds. The approach contrasts with past resource management in which managers frequently tackled problems with minimal coordination between disciplines (e.g., water, wildlife, cultural resources, and maintenance) and locations. The result has been a series of projects that have begun to measurably improve the health of one of the park’s most visited and iconic watersheds: the Cromwell Brook watershed, which includes Sieur de Monts (Acadia began in 1916 as Sieur de Monts National Monument) and the Great Meadow, and whose namesake waterway flows through the gateway town of Bar Harbor. Projects (inside and out of the park) have included rehabilitating a historic spring pool, replacing undersized culverts with open-bottom bridges, removing a poorly sited septic system, removing invasive plants, restoring native wetland, establishing monitoring to assess changes in watershed health, and working with the town and other stakeholders to plan future projects that would further improve the health of Great Meadow and downstream areas in Bar Harbor. The combination of planning; monitoring; restoring healthy, functioning ecological communities; and minimizing stresses from human infrastructure and visitation offer the best chance of main- taining Acadia National Park for the enjoyment of future generations
Final report : task 4 : waste minimisation in construction
The Regenerating Construction Project for the CRC for Construction Innovation aims to
assist in the delivery of demonstrably superior ‘green’ buildings. Components of the
project address eco-efficient redesign, achieving a smaller ecological footprint,
enhancing indoor environment and minimising waste in design and construction. The
refurbishment of Council House 1 for Melbourne City Council provides an opportunity
to develop and demonstrate tools that will be of use for commercial building
refurbishment generally. It is hoped that the refurbishment will act as an exemplar
project to demonstrate environmentally friendly possibilities for office building
refurbishment
Recommended from our members
Design for manufacture and sustainability in new product development
Design for manufacture is well recognised by industry and is about optimising design to aid production. Today there is a significant and growing trend of recognising what happens to a product once its user phase has finished. Post-consumer processes are now an important consideration during the ab-initio stages of design. Rather than a focus limited to design for manufacture or (more recently) design for assembly now the pressure is on for post consumer design. Companies need to do this because legislative pressures are increasing and consumers are becoming ever more aware of, and concerned about, environmental issues. End-of-life processing and design for the environment are therefore areas of growing of interest. This conference paper investigates with industry practitioners their experiences regarding for both the environmental and economic advantages of product life-cycle planning. Legislative pressures and consumer awareness are driving businesses to develop sustainable product design strategies (Jones et al, 2001 p. 27). Changes within the law, to protect our environment, cause companies to pay attention as they begin to affect profitability. The first British Standard to address design for end-of-life processing, and therefore support industry, is BS 8887-1. Over 60 UK manufacturing and design companies that had bought BS 8887-1 contributed to this by being interviewed or providing a written response. The research investigated multiple aspects of sustainable design in practice however, in this conference paper the focus is its application within the design process
Institutions Compromising Academics for Athletic and Economic Reward
Student athletes are an integral part of NCAA divisions, specifically student athletes of color. Through research regarding athletic and economic statistics, it has been proven that the necessity of talent in athletics is far more important than success in academics. Student athletes are often represented through their role as an athlete first, then followed by the role of the student. Graduation rates, athletic success, and economic profit is all explored in a racial context in this paper in order to further prove the exploitation that institutions involve themselves in
- …