15 resultados para Mechanism design

em Deakin Research Online - Australia


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Taking advantage of the huge potential of consumers’ untapped computing power, self-organizing cloud is a novel computing paradigm where the consumers are able to contribute/sell their computing resources. Meanwhile, host machines held by the consumers are connected by a peer-to-peer (P2P) overlay network on the Internet. In this new architecture, due to large and varying multitudes of resources and prices, it is inefficient and tedious for consumers to select the proper resource manually. Thus, there is a high demand for a scalable and automatic mechanism to accomplish resource allocation. In view of this challenge, this paper proposes two novel economic strategies based on mechanism design. Concretely, we apply the Modified Vickrey Auction (MVA) mechanism to the case where the resource is sufficient; and the Continuous Double Auction (CDA) mechanism is employed when the resource is insufficient. We also prove that aforementioned mechanisms have dominant strategy incentive compatibility. Finally, extensive experiment results are conducted to verify the performance of the proposed strategies in terms of procurement cost and execution efficiency.

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Purpose – The purpose of this paper is to investigate the aerodynamics characteristics (especially the side force/moment and rolling characteristics), to analyze the impacts generated by different parameters of wrap-around fins (WAFs) and to find the corresponding mechanism.Design/methodology/approach – The paper has adopted three different types of WAFs for the rocket configurations and the sub-regions dividedtechnology to investigate the lateral and rolling characteristics of WAFs, including the fins with variations in span to chord ratio, thickness,leading-edge sweep, curvature radius, fin numbers, setting angles and rotated angles. Simulations have been performed at Mach numbers from 3 to 4 through an angle-of-attack range of about 0° to 10° and at model rolling angles of 45° to 90°.Findings – The paper shows that the WAF configurations can greatly improve the longitudinal stability and enhance the longitudinal aerodynamic characteristics for the whole rocket. The total drag of the whole rocket is mainly stemmed from the body, while the drag generated by the WAF account for only about 7.42 per cent. The extra side forces and rolling moments are due largely to the unequal pressure distributions on both sides of the fin (windward or leeward). Maintaining a certain negative setting angle (d) can effectively avoid the coning movement and improve the flight stability at high angles of attack. The size of the span and chord are two main factors in controlling the longitudinal characteristics. For the side force/moment and rolling characteristics, different geometric parameters of the WAFs have played different roles.Originality/value – The paper provides the qualitative and quantitative analysis for different WAFs configurations by investigating the curves ofdifferent parameters and contouring of static pressure distributions. Findings can provide some suggestions for the designers for avoiding some significant dynamic problems, such as Magnus instability and roll rate variations during flight.

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Carbon payments can help mitigate both climate change and biodiversity decline through the reforestation of agricultural land. However, to achieve biodiversity co-benefits, carbon payments often require support from other policy mechanisms such as regulation, targeting, and complementary incentives. We evaluated 14 policy mechanisms for supplying carbon and biodiversity co-benefits through reforestation of carbon plantings (CP) and environmental plantings (EP) in Australia's 85.3 Mha agricultural land under global change. The reference policy - uniform payments (bidders are paid the same price) with land-use competition (both CP and EP eligible for payments), targeting carbon - achieved significant carbon sequestration but negligible biodiversity co-benefits. Land-use regulation (only EP eligible) and two additional incentives complementing the reference policy (biodiversity premium, carbon levy) increased biodiversity co-benefits, but mostly inefficiently. Discriminatory payments (bidders are paid their bid price) with land-use competition were efficient, and with multifunctional targeting of both carbon and biodiversity co-benefits increased the biodiversity co-benefits almost 100-fold. Our findings were robust to uncertainty in global outlook, and to key agricultural productivity and land-use adoption assumptions. The results suggest clear policy directions, but careful mechanism design will be key to realising these efficiencies in practice. Choices remain for society about the amount of carbon and biodiversity co-benefits desired, and the price it is prepared to pay for them.

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To have an effective and efficient mechanism to store, manage and utilize software sources is essential to the automation of software engineering. The paper presents an innovative approach in managing software resources using software warehouse where software assets are systematically accumulated, deposited, retrieved, packaged, managed and utilized, driven by data-mining and OLAP technologies. The results lead to streamlined high efficient software development process and enhance the productivity in response to modern challenges of the design and development of software applications.

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Parallel file systems offer improved performance over traditional file systems by allowing processes to access file data, stored over a number of disks, in parallel. When this file is to be accessed by many processes at the same time for reading and writing, the problem of maintaining file consistency is introduced. The general approach to maintaining file consistency is through the use locks which grant a single process exclusive access to the file. Existing studies have found parallel file systems and associated applications rarely experience conflict, resulting in unnecessary overheads from locks being acquired. This paper examines an alternate approach to maintaining file consistency, which is based on optimistic concurrency control. This approach was shown to have a much smaller overhead when compared with traditional lock-based approaches; especially in situations when there is little contention. This paper presents the design, implementation and initial testing results of an optimistic based concurrency control mechanism.

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For some time now Tony Fry has promoted the idea of 'The Sustainment', an idea that asserts a paradigm shift in attitudes to consumption. 'The Sustainment' recognises that increasingly human futures are products of self-determination and not chance. Fry’s hypothesis can be understood through his concept of Defuturing, a philosophy that questions the role of design and the responsibility of designers to facilitating the ability to sustain (Fry 1999).
Central to Fry’s philosophy is an awareness that it is in the best interests of designers and their clients, as inhabitants of cultures increasingly driven by technology, to be aware of the relationships between the products and theories of design and the processes and implications of technological change. This is an awareness that is central to the concepts, work, and methodologies of the ‘UN Studio’ of Van Berkel and Bos described and elaborated upon in Move – Imagination, Techniques, and Effects (Van Berkel & Bos 1999). Here, Ben Van Berkel defines the parameters and methodologies employed by UN Studio in an environment of technological and socio-economic change. The Dutch practice could be said to exemplify something of a zeitgeist in current architectural design that sees architects, as Van Berkel and Bos view them, as “fashion designers of the future, dressing events to come and holding up a mirror to the world (Van Berkel & Bos 1999, back cover).” It is a zeitgeist that Fry might see as aligned to the resilient hype of ‘new creativity’, ‘globalisation’ the ‘romance with technology’, and the vacuous-ness of the world of fashion. (Fry The Voice of Sustainment: on Design Intelligence 2005).
A source of breaking down such design propaganda is identified by Fry in the notion of ‘scenarios,’ which “provide a mechanism for politico-practice assemblage in which dialogues and narratives of change can be rehearsed in ways that enable participants to re-educate themselves via critical confrontations” (Fry The Voice of Sustainment: on Design Intelligence 2005). From such a perspective this paper aims to practically illustrate and ground the Defuturing of Fry by establishing a dialogue between his writings and the theories that have generated the architectural designs of Van Berkel and Bos and there UN Studio. This will be a ‘scenario’ that examines therefore an appropriation and transformation of the applied intellectual practice of Van Berkel and Bos. Through this confrontation we shall explore the question of why sustainability appears to be so low in the agenda of many pre-eminent contemporary architects, and how we might refocus therefore practice and theory on the ability to sustain.

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We designed and implemented a traffic accident analysis system (TAAS) in the paper. TAAS is the system faced traffic accident analysis, which uses the traffic rules (law) as knowledge sources to judge if the driver is responsible for a traffic accident. TAAS has characteristics of separating knowledge base and inference engine, using production rule and backward chaining. Besides, TAAS used predefined text and tracing program to realize explanation mechanism.

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This paper explores the idea of responsible systems design. To do so, it examines a case study - the accreditation of Information Systems (IS) courses by the professional body. A professionally accredited educational program, like any other non-trivial design product, represents the balancing of competing influences, ideas and stakeholders. The case is particularly relevant because there have been significant changes in the context of Australian IS education recently that have made more complex the task of designing educational systems in a responsible manner. A general approach to addressing this complexity is articulated here as a design pattern to guide IS educational design. The pattern identifies the influences on design, the processes and products of design and the feedback mechanism required to demonstrate that stakeholder requirements are satisfied. Design tensions and principles arising from the model are discussed and future work identified

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Interaction with virtual or teleoperated environments requires contact with objects on a multipoint level. We describe the design of a pinch--grasp hand interface device for use as a grasping mechanism to complement haptic interfaces. To preserve a suitable level of transparency for human--computer interaction, this novel interface is designed for high-resolution contact forces, while centered around a lightweight structure. This functionality renders the device scalable and adaptable to a wide range of haptic interface structures and force level requirements. We present an optimal configuration for a pinch--grasp interface, which produces bidirectional forces to an operator's fingers and a rotational force to the wrist through a cable drive system. The device is characterized for use on a commercial haptic interface through demonstration of sustained peak performance and also workspace utilization. The dynamic performance of the pinch--grasp interface is experimentally determined, and the frequency response is identified to illustrate its contact force resolution.

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The Smith machine is a pervasive weight-training apparatus, used extensively by a wide population of weight trainers, from novices to high-level athletes. The advantages of using a Smith machine over free-weight resistance are disputed, with conflicting findings reported in the literature. In this study, we are interested in practical differences between 3 types of loading mechanisms found in modern Smith machines. In addition to the basic design comprising a constrained weighted barbell, alterations with a counterweight and a viscous resistance component are examined. The approach taken is that of employing a recently proposed representation of force characteristics that may be exhibited by a trainee and a predictive model of thus effected adaptation. A computer simulation is used to predict the effects of the 3 linear Smith machine designs in the framework of different exercise protocols. Our results demonstrate that each resistance component, vertically constrained load, counterweight, and viscous, can be matched with a particular training context, in which it should be preferred. Thus, a number of practical guidelines for weight-training practitioners are recommended. In summary, (a) at low intensities (55–75% of 1 repetition maximum [1RM]) used in strength-endurance training, a viscous resistance containing the Smith machine was found to offer advantages over both a constrained load only and counterweighted designs; (b) at medium intensities (75–85% of 1RM) typically employed in hypertrophy-specific training, the counterweighted Smith machine design was found to offer the best choice in terms of high-force development and total external work performed; finally, (c) at high training intensity (90–100% of 1RM), the optimal prescription was found to be more dependent on the specific athlete’s weaknesses, highlighting the need for continual monitoring of the athlete’s force production capabilities. To ensure that appropriate adjustments are made to the athlete’s training regimen, the practitioner should consider the full set of findings of this article and the accompanying discussion.

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Recently, Wang et al. presented a new construction of attribute-based signature with policy-and-endorsement mechanism. The existential unforgeability of their scheme was claimed to be based on the strong Diffie-Hellman assumption in the random oracle model. Unfortunately, by carefully revisiting the design and security proof of Wang et al.’s scheme, we show that their scheme cannot provide unforgeability, namely, a forger, whose attributes do not satisfy a given signing predicate, can also generate valid signatures. We also point out the flaws in Wang et al.’s proof.

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This research aims to develop an iron oxide nanoparticle drug delivery system utilizing a recent material discovered from ocean, fucoidan. The material has drawn much interest due to many biomedical functions that have been proven for human health. One interesting point herein is that fucoidan is not only a sulfated polysaccharide, a polymer for stabilization of iron oxide nanoparticles, but plays a role of an anticancer agent also. Various approaches were investigated to optimize the high loading efficiency and explain the mechanism of nanoparticle formations. Fucoidan was functionalized on iron oxide nanoparticles by a direct coating or via amine groups. Also, a hydrophobic part of oleic acid was conjugated to the amine groups for a more favorable loading of poorly water-soluble anticancer drugs. This study proposed a novel system and an efficient method to functionalize fucoidan on iron oxide nanoparticle systems which will lead to a facilitation of a double strength treatment of cancer.

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Perspectives on Architectural Design Research is a collection of short essays, projects and edited transcripts that offers current perspectives on design research in architecture and aligned disciplines. Contributors include international figures Donald L. Bates, Richard Blythe, Nat Chard, Murray Fraser, Dorita Hannah, Jonathan Hill and Vivian Mitsogianni. What emerges from the multiple perspectives is that contemporary design research – transdisciplinary, multi-scalar and concerning place, people, space and time – provides a collective and subtle mechanism that is propositional and transformative. The shared optimism of the contributors is that this propositional mode of research can be of catalytic value for contemporary culture and society

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It is argued that ‘design' is an essential characteristic of engineering practice, and hence, an essential theme of engineering education. It is suggested that first-year design courses enhance commencing student motivation and retention, and introduce engineering application content and basic design experience early in the curriculum. The research literature indicates that engineering design practice is a deeply social process, with collaboration and group interactions required at almost every stage. This chapter documents the evaluation of the initial and subsequent second offerings of a first-year engineering design unit at Griffith University in Australia. The unit 1006ENG Design and Professional Skills aims to provide an introduction to engineering design and professional practice through a project-based approach to problem solving. The unit learning design incorporates student group work, and uses self-and-peer-assessment to incorporate aspects of the design process into the unit assessment and to provide a mechanism for individualization of student marks.

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The truss bolt reinforcement system has been used in controlling the stability of underground excavations in severe ground conditions and cutter roof failure in layered rocks especially in coal mines. In spite of good application reports, working mechanism of this system is largely unknown and truss bolts are predominantly designed based on past experience and engineering judgement. In this study, the reinforcing effect of the truss bolt system on an underground excavation in layered rock is studied using non-linear finite element analysis. Different indicators are defined to evaluate the reinforcing effects of the truss bolt system. Using these indicators one can evaluate the effects of a reinforcing system on the deformation, loosened area, failure prevention, horizontal movement of the immediate layer, shear crack propagation and cutter roof failure of underground excavations. Effects of truss bolt on these indicators reveal the working mechanism of the truss bolt system. To illustrate the application of these indicators, a comparative study is conducted between three different truss bolt designs. It is shown that the design parameters of truss bolt systems, including tie-rod span, length, and angle of the bolts can have significant effects on the reinforcing capability of the system.