Sound radiation characteristics of a box-type structure

The finite element and boundary element methods are employed in this study to investigate the sound radiation characteristics of a box-type structure. It has been shown [T.R. Lin, J. Pan, Vibration characteristics of a box-type structure, Journal of Vibration and Acoustics, Transactions of ASME 131 (2009) 031004-1–031004-9] that modes of natural vibration of a box-type structure can be classified into six groups according to the symmetry properties of the three panel pairs forming the box. In this paper, we demonstrate that such properties also reveal information about sound radiation effectiveness of each group of modes. The changes of radiation efficiencies and directivity patterns with the wavenumber ratio (the ratio between the acoustic and the plate bending wavenumbers) are examined for typical modes from each group. Similar characteristics of modal radiation efficiencies between a box structure and a corresponding simply supported panel are observed. The change of sound radiation patterns as a function of the wavenumber ratio is also illustrated. It is found that the sound radiation directivity of each box mode can be correlated to that of elementary sound sources (monopole, dipole, etc.) at frequencies well below the critical frequency of the plates of the box. The sound radiation pattern on the box surface also closely related to the vibration amplitude distribution of the box structure at frequencies above the critical frequency. In the medium frequency range, the radiated sound field is dominated by the edge vibration pattern of the box. The radiation efficiency of all box modes reaches a peak at frequencies above the critical frequency, and gradually approaches unity at higher frequencies.

The MESH book : landscape / infrastructure

Resulting from a series of student-run 'Edge' conferences that have been held in Australia and New Zealand (beginning at RMIT in 1983), The Mesh Book is a collection of essays grouped into themes of Invisible Infrastructures (systems of belief), Immanent Infrastructures (natural systems) and Present Infrastructures (roads and services). Ranging from esoteric discussions to analytical case studies, the book assembles a broad spectrum of ideas on the landscape within the context of Australia and a contemporary study of place.

Supporting pre-tender construction planning with virtual prototyping

Purpose – Virtual prototyping technologies linked to building information models are commonplace within the aeronautical and automotive industries. Their use within the construction industry is now emerging. The purpose of this paper is to show how these technologies have been adopted on the pre-tender planning for a typical construction project. Design/methodology/approach – The research methodology taken was an “action research” approach where the researchers and developers were actively involved in the production of the virtual prototypes on behalf of the contractor thereby gaining consistent access to the decisions of the planning staff. The experiences from the case study were considered together with similar research on other construction projects. Findings – The findings from the case studies identify the role of virtual prototyping in components modelling, site modelling, construction equipment modelling, temporary works modelling, construction method visualization and method verification processes. Originality/value – The paper presents a state-of-the-art review and discusses the implications for the tendering process as these technologies are adopted. The adoption of the technologies will lead to new protocols and changes in the procurement of buildings and infrastructure.

Annual Review : practice and research in career counseling and development – 2008

The career development literature published in 2008 is summarized and presented thematically: (a) professional issues, (b) career assessment, (c) career development, (d) career theory and concepts, (e) career interventions, (f) advances in technology, (g) employment, (h) international perspectives, and (i) research design and methodology. Traditional and emerging theories and practices are robust and vibrant.

Low-complexity estimation of CFO and frequency independent I/Q mismatch for OFDM systems

CFO and I/Q mismatch could cause significant performance degradation to OFDM systems. Their estimation and compensation are generally difficult as they are entangled in the received signal. In this paper, we propose some low-complexity estimation and compensation schemes in the receiver, which are robust to various CFO and I/Q mismatch values although the performance is slightly degraded for very small CFO. These schemes consist of three steps: forming a cosine estimator free of I/Q mismatch interference, estimating I/Q mismatch using the estimated cosine value, and forming a sine estimator using samples after I/Q mismatch compensation. These estimators are based on the perception that an estimate of cosine serves much better as the basis for I/Q mismatch estimation than the estimate of CFO derived from the cosine function. Simulation results show that the proposed schemes can improve system performance significantly, and they are robust to CFO and I/Q mismatch.

What lies beneath? : The pattern and abundance of the subterranean tuber bank of the invasive liana cat’s claw creeper, Macfadyena unguis-cati (Bignoniaceae)

Cat’s claw creeper, Macfadyena unguis-cati (L.) Gentry (Bignoniaceae) is a major environmental weed of riparian areas, rainforest communities and remnant natural vegetation in coastal Queensland and New South Wales, Australia. In densely infested areas, it smothers standing vegetation, including large trees, and causes canopy collapse. Quantitative data on the ecology of this invasive vine are generally lacking. The present study examines the underground tuber traits of M. unguis-cati and explores their links with aboveground parameters at five infested sites spanning both riparian and inland vegetation. Tubers were abundant in terms of density (~1000 per m2), although small in size and low in level of interconnectivity. M. unguis-cati also exhibits multiple stems per plant. Of all traits screened, the link between stand (stem density) and tuber density was the most significant and yielded a promising bivariate relationship for the purposes of estimation, prediction and management of what lies beneath the soil surface of a given M. unguis-cati infestation site. The study also suggests that new recruitment is primarily from seeds, not from vegetative propagation as previously thought. The results highlight the need for future biological-control efforts to focus on introducing specialist seed- and pod-feeding insects to reduce seed-output.

A study of vibration and vibration control of ship structures

This paper examines the vibration characteristics and vibration control of complex ship structures. It is shown that input mobilities of a ship structure at engine supports, due to out-of-plane force or bending moment excitations, are governed by the flexural stiffness of the engine supports. The frequency averaged input mobilities of the ship structure, due to such excitations, can be represented by those of the corresponding infinite beam. The torsional moment input mobility at the engine support can be estimated from the torsional response of the engine bed section under direct excitation. It is found that the inclusion of ship hull and deck plates in the ship structure model has little effect on the frequency-averaged response of the ship structure. This study also shows that vibration propagation in complex ship structures at low frequencies can be attenuated by imposing irregularities to the ring frame locations in ships. Vibration responses of ship structures due to machinery excitations at higher frequencies can be controlled by structural modifications of the local supporting structures such as engine beds in ships.

Consumers' accounts of perceived risk online and the influence of communication sources

The purpose of this paper is to extend marketing knowledge into perceived risk in online transactions beyond the current positivistic, hypotheses-driven research by providing qualitative insights into how individuals construct their accounts of perceived risk online. Additionally, the study reported in this paper aims to explore how communication sources influence both these subjective constructions and individuals' behavioural experiences with transaction activity on the web. Design/methodology/approach - The study was developed within a grounded theory method.Ten in-depth interviews were conducted which were analysed using constant comparison of incidents procedures to provide rich descriptions of the interviewees' subjective perceptions and lived experiences with online transaction activity. Findings - The findings provide insights into how the human clement is present in individuals'perceptions and constructions of their accounts of the risk involved online.The findings also identify the influence of mass communication sources on the construction of these accounts. The study provides insights into whether change agent communication sources, such as marketers or web designers,influence consumers' behaviours towards online transaction activity through mediating their perceptions of the risks involved. The study also reveals how social communication networks influence the interviewees' decisions to use the web (or transaction activities, in particular online purchasing, and how the group in this study might act as a communication source to influence others. Research limitations/Implications - While the findings cannot be generalised to the internet population overall, the sample used was able to provide relevant information regarding the phenomenon of interest. Future research should continue to examine perceived risk and the influence of communications sources, such as e-mail, discussion groups and virtual communities. Originality/value - The value of the paper lies in permitting the participants to account for perceived risk for themselves. The findings ex.plore what this means at increasing levels of personal relevance and the influence of communication sources to create, sustain or mediate perceptions of this phenomenon.

"Get new lawyers!"

In James Rubin's account of the Kosovo war, he describes an exchange between Secretary Albright and Robin Cook (the British Foreign Secretary). Cook was explaining that it is difficult for Britain to commit to the war without UN Security Council approval because the legal advice he had received was that such action would be illegal under international law. Albright's response was, simply, "get new lawyers". Rubin "credits" Blair with a "push" that swung the British to "finally agree" that a UN Security Council resolution was "not legally required". Robin Cook later stated in Parliament and that the war was legal. Interestingly, Blair did not. This article does not look at whether or not such an exchange took place; rather look at the ethical issues that such a situation would generate. The article suggests what the ethical obligations of the key legal players in such institutional dramas should be—including governments seeking advice, the lawyers giving it, the ministers reporting it and the opposition in Parliament. The article sets out the particular responsibilities of the lawyers and officials of a Westminster system. It also sets out some of the institutional mechanisms for making it more likely that those obligations are fulfilled—as always through the interaction of obligations by different players that make it more risky for any player to breach his or her ethical obligations. Analogous duties would be faced by the relevant actors in other systems.

Doing cultural heritage using the torque game engine: supporting indigenous storytelling in a 3D virtual environment

Digital Songlines (DSL) is an Australasian CRC for Interaction Design (ACID) project that is developing protocols, methodologies and toolkits to facilitate the collection, education and sharing of indigenous cultural heritage knowledge. This paper outlines the goals achieved over the last three years in the development of the Digital Songlines game engine (DSE) toolkit that is used for Australian Indigenous storytelling. The project explores the sharing of indigenous Australian Aboriginal storytelling in a sensitive manner using a game engine. The use of the game engine in the field of Cultural Heritage is expanding. They are an important tool for the recording and re-presentation of historically, culturally, and sociologically significant places, infrastructure, and artefacts, as well as the stories that are associated with them. The DSL implementation of a game engine to share storytelling provides an educational interface. Where the DSL implementation of a game engine in a CH application differs from others is in the nature of the game environment itself. It is modelled on the 'country' (the 'place' of their heritage which is so important to the clients' collective identity) and authentic fauna and flora that provides a highly contextualised setting for the stories to be told. This paper provides an overview on the development of the DSL game engine.

More and more lawyers but still no judges

This paper discusses some parallels and contrasts between the legal roads to war and suggest that the case is stronger than ever for adjudication of the matter before an independent tribunal where the competing views can be tested.

Washout hole for bi-ventricular assist device (BVAD) centrifugal blood pump

The shortage of donor hearts for patients with end stage heart failure has accelerated the development of ventricular assist devices (VAD) that act as a replacement heart. Mechanical devices involving pulsatile, axial and centrifugal devices have been proposed. Recent clinical developments indicate that centrifugal devices are not only beneficial for bridge to transplantation applications, but may also aid myocardial recovery. The results of a recent study have shown that patients who received a VAD have extended lives and improved quality of life compared to recipients of drug therapy. Unfortunately 25% of these patients develop right heart failure syndrome, sepsis and multi-organ failure. It was reported that 17% of patients initially receiving an LVAD later required a right ventricular assist device (RVAD). Hence, current research focus is in the development of a bi-ventricular assist device (BVAD). Current BVAD technology is either too bulky or necessitates having to implant two pumps working independently. The latter requires two different controllers for each pump leading to the potential complication of uneven flow dynamics and the requirements for a large amount of body space. This paper illustrates the combination of the LVAD and RVAD as one complete device to augment the function of both the left and right cardiac chambers with double impellers. The proposed device has two impellers rotating in counter directions, hence eliminating the necessity of the body muscles and tubing/heart connection to restrain the pump. The device will also have two separate chambers with independent rotating impeller for the left and right chambers. A problem with centrifugal impellers is the fluid stagnation underneath the impeller. This leads to thrombosis and blood clots.This paper presents the design, construction and location of washout hole to prevent thrombus for a Bi-VAD centrifugal pump. Results using CFD will be used to illustrate the superiority of our design concept in terms of preventing thrombus formation and hemolysis.

Computational fluid dynamics of a centrifugal heart pump as biventricular assist device(BVAD)

The results of a recent study have shown that there is a severe shortage of donor hearts to meet the demand of patients suffering from acute heart failures, and patients who received a left ventricular assist device (LVAD) have extended lives. However, some of them develop right heart failure syndrome, and these patients required a right ventricular assist device (RVAD). Hence, current research focus is in the development of a bi-ventricular assist device (Bi-VAD). Computational Fluid Dynamics (CFD) is useful for estimating blood damage for design of a Bi-VAD centrifugal heart pump to meet the demand of the left and right ventricles of a normal hearts with a flow rate of 5 lit/min and the supply pressure of 100 mmHg for the left ventricle and 20 mmHg for the right ventricle. Numerical studies have been conducted to predict pressure, flow rate, the velocity profiles, and streamlines in a continuous flow Bi-VAD using. Based on the predictions of numerical simulations, only few flow regions in the Bi-VAD exhibited signs of velocity profiles and stagnation points, thereby signifying potentially low levels of thrombogenesis.

TV stories : from representation to productivity

This chapter revisits the concept of the ‘bardic function’ (Fiske & Hartley 1978), using historical analysis of the oral bardic institutions to re-theorise it for the era of interactive media and digital storytelling. It shows how ‘representative’ storytelling has transformed into self-representation, and proposes that the ‘bardic function’ can be divided into three types: representative (the ‘Taliesin function’); pedagogic (the ‘Gandalf function’); and self-organised (the ‘eisteddfod function’).