1000 resultados para Viscous regime


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A numerical study is presented to examine the fingering instability of a gravity-driven thin liquid film flowing down the outer wall of a vertical cylinder. The lubrication approximation is employed to derive an evolution equation for the height of the film, which is dependent on a single parameter, the dimensionless cylinder radius. This equation is identified as a special case of that which describes thin film flow down an inclined plane. Fully three-dimensional simulations of the film depict a fingering pattern at the advancing contact line. We find the number of fingers observed in our simulations to be in excellent agreement with experimental observations and a linear stability analysis reported recently by Smolka & SeGall (Phys Fluids 23, 092103 (2011)). As the radius of the cylinder decreases, the modes of perturbation have an increased growth rate, thus increasing cylinder curvature partially acts to encourage the contact line instability. In direct competition with this behaviour, a decrease in cylinder radius means that fewer fingers are able to form around the circumference of the cylinder. Indeed, for a sufficiently small radius, a transition is observed, at which point the contact line is stable to transverse perturbations of all wavenumbers. In this regime, free surface instabilities lead to the development of wave patterns in the axial direction, and the flow features become perfectly analogous to the two-dimensional flow of a thin film down an inverted plane as studied by Lin & Kondic (Phys Fluids 22, 052105 (2010)). Finally, we simulate the flow of a single drop down the outside of the cylinder. Our results show that for drops with low volume, the cylinder curvature has the effect of increasing drop speed and hence promoting the phenomenon of pearling. On the other hand, drops with much larger volume evolve to form single long rivulets with a similar shape to a finger formed in the aforementioned simulations.

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Since 1 December 2002, the New Zealand Exchange’s (NZX) continuous disclosure listing rules have operated with statutory backing. To test the effectiveness of the new corporate disclosure regime, we compare the change in quantity of market announcements (overall, non-routine, non-procedural and external) released to the NZX before and after the introduction of statutory backing. We also extend our study in investigating whether the effectiveness of the new corporate disclosure regime is diminished or augmented by corporate governance mechanisms including board size, providing separate roles for CEO and Chairman, board independence, board gender diversity and audit committee independence. Our findings provide a qualified support for the effectiveness of the new corporate disclosure regime regarding the quantity of market disclosures. There is strong evidence that the effectiveness of the new corporate disclosure regime was augmented by providing separate roles for CEO and Chairman, board gender diversity and audit committee independence, and diminished by board size. In addition, there is significant evidence that share price queries do impact corporate disclosure behaviour and this impact is significantly influenced by corporate governance mechanisms. Our findings provide important implications for corporate regulators in their quest for a superior disclosure regime.

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The chapter examines the current emission reduction obligations within the climate regime. It looks at the formation and rise of the BASIC negotiation group within the international climate COP negotiations and examines the role that BASIC nations are now playing shaping international mitigation policy.

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Following a trial in June 2009 where the Federal Court heard submissions regarding whether Merck Sharpe and Dohme Australia should be held liable for an increased risk of cardiovascular conditions noted in patients who had taken the anti-inflammatory drug Vioxx, a judgment was handed down against MSDA in March 2010. MSDA appealed to the Full Federal Court, where they were successful. Special leave to appeal to the High Court of Australia was rejected in May 2012. This article will examine the themes raised in the trial judgment and the appropriateness of Australia’s statutory consumer protection regime through the lens of pharmaceutical drug injuries and side effects.

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The principle of common but differentiated responsibility (CBDR) will play a role in the 2020 Climate Regime. This Article starts by examining differential treatment within the international legal order, finding that it is ethically and practically difficult to implement an international climate instrument based on formal equality. There is evidence of state parties accepting differential responsibilities in a number of areas within the international legal order and the embedding of CBDR in the United Nations Framework Convention on Climate Change (UNFCCC), means that that differential commitments will lie at the heart of the 2020 climate regime. The UNFCCC applies the implementation method of differentiation, while the Kyoto Protocol applies both the obligation and implementation method of differentiation. It is suggested that the implementation model will be the differentiation model retained in the 2020 climate agreement. The Parties’ submissions under the Durban Platform are considered in order to gain an understanding of their positions on CBDR. While there are areas of contention including the role of principles in shaping obligations and the ongoing legal status of Annex I and Non-Annex I distinction, there is broad consensus among the parties in favour of differentiation by implementation with developed and major economies undertaking Quantified Emission Limitation and Reduction Objectives (economy wide targets) and developing countries that are not major economies undertaking sectoral targets.

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This article investigates the extent to which the purported greening of food retailing and consumption in Australia is consistent with the development of a corporate-environmental food regime. Recent developments in food regime theory, particularly the concept of an emerging third food regime (the so-called ‘corporate-environmental food regime’), provide a useful organizing framework for understanding recent agri-restructuring trends. We find that, while a globally based, third food regime is becoming more apparent, the attributes that relate to corporate retail-driven greening of the supply chain are less evident within Australia’s domestic market than in its EU counterparts. However, there is some evidence that Australia’s export market is subject to some degree of ‘greening at a distance’ due to private regulations imposed by supermarkets overseas. We argue that while broader agri-restructuring trends may be evident at an international level, elements of greening specific to national contexts are important for determining the trajectory of any third food regime.

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The effect of radiation on natural convection of Newtonian fluid contained in an open cavity is investigated in this study. The governing partial differential equations are solved numerically using the Alternate Direct Implicit method together with the Successive Over Relaxation method. The study is focused on studying the flow pattern and the convective and radiative heat transfer rates are studied for different values of radiation parameters namely, the optical thickness of the fluid, scattering albedo, and the Planck number. It was found that in the optically thin limit, an increase in the optical thickness of the fluid raises the temperature and radiation heat transfer of the fluid. However, a further increase in the optical thickness decreases the radiative heat transfer rate due to increase in the energy level of the fluid, which ultimately reduces the total heat transfer rate within the fluid.

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The theoretical analysis of the bistability associated with the excitation of surface magnetoplasma waves (SWs) propagating across an external magnetic field at the semiconductor-metal interface by the attenuated total reflection (ATR) method is presented. The Kretschmann-Raether configuration of the ATR method is considered, i.e. a plane electromagnetic wave is incident onto a metal surface through a coupling prism. The third-order nonlinearity of the semiconductor medium is considered in the general form using the formalism of the third-order nonlinear susceptibilities and of the perturbation theory. The examples of the nonlinear mechanisms which influence the SW propagation are given. The analytical and numerical analyses show that the realization of bistable regimes of the SW excitation is possible. The SW amplitude values providing bistability in the structure are evaluated and are reasonably low to provide the experimental observation.

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This article examines the new Property Occupations Act 2014 (POA) and relevant provisions of the Agents Financial Administration Act 2014 (AFAA) and the impacts for property practitioners. The Acts are due to commence later in 2014 once regulations and relevant forms are drafted. Coinciding with the commencement of the Acts further versions of the REIQ Houses and Land Contract and REIQ Community Title Contract will also be released. The POA introduces changes for licencing of real estate agents, property developers and resident letting agents as well as significant changes for the contract formation process. The AFAA includes the trust account and claim fund provisions of PAMDA, which avoids duplication of these provisions across each of the industry-specific Bills. The most significant change is to the process for making a claim against the fund for the conduct of property agents.

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The Kyoto Protocol is remarkable among global multilateral environmental agreements for its efforts to depoliticize compliance. However, attempts to create autonomous, arm’s length and rule-based compliance processes with extensive reliance on putatively neutral experts were only partially realized in practice in the first commitment period from 2008 to 2012. In particular, the procedurally constrained facilitative powers vested in the Facilitative Branch were circumvented, and expert review teams (ERTs) assumed pivotal roles in compliance facilitation. The ad hoc diplomatic and facilitative practices engaged in by these small teams of technical experts raise questions about the reliability and consistency of the compliance process. For the future operation of the Kyoto compliance system, it is suggested that ERTs should be confined to more technical and procedural roles, in line with their expertise. There would then be greater scope for the Facilitative Branch to assume a more comprehensive facilitative role, safeguarded by due process guarantees, in accordance with its mandate. However, if – as appears likely – the future compliance trajectories under the United Nations Framework Convention on Climate Change will include a significant role for ERTs without oversight by the Compliance Committee, it is important to develop appropriate procedural safeguards that reflect and shape the various technical and political roles these teams currently play.

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In ecosystems driven by water availability, plant community dynamics depend on complex interactions between vegetation, hydrology, and human water resources use. Along ephemeral rivers—where water availability is erratic—vegetation and people are particularly vulnerable to changes in each other's water use. Sensible management requires that water supply be maintained for people, while preserving ecosystem health. Meeting such requirements is challenging because of the unpredictable water availability. We applied information gap decision theory to an ecohydrological system model of the Kuiseb River environment in Namibia. Our aim was to identify the robustness of ecosystem and water management strategies to uncertainties in future flood regimes along ephemeral rivers. We evaluated the trade-offs between alternative performance criteria and their robustness to uncertainty to account for both (i) human demands for water supply and (ii) reducing the risk of species extinction caused by water mining. Increasing uncertainty of flood regime parameters reduced the performance under both objectives. Remarkably, the ecological objective (species coexistence) was more sensitive to uncertainty than the water supply objective. However, within each objective, the relative performance of different management strategies was insensitive to uncertainty. The ‘best’ management strategy was one that is tuned to the competitive species interactions in the Kuiseb environment. It regulates the biomass of the strongest competitor and, thus, at the same time decreases transpiration, thereby increasing groundwater storage and reducing pressure on less dominant species. This robust mutually acceptable strategy enables species persistence without markedly reducing the water supply for humans. This study emphasises the utility of ecohydrological models for resource management of water-controlled ecosystems. Although trade-offs were identified between alternative performance criteria and their robustness to uncertain future flood regimes, management strategies were identified that help to secure an ecologically sustainable water supply.

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Light-emitting field effect transistors (LEFETs) are an emerging class of multifunctional optoelectronic devices. It combines the light emitting function of an OLED with the switching function of a transistor in a single device architecture the dual functionality of LEFETs has the potential applications in active matrix displays. However, the key problem of existing LEFETs thus far has been their low EQEs at high brightness, poor ON/OFF and poorly defined light emitting area-a thin emissive zone at the edge of the electrodes. Here we report heterostructure LEFETs based on solution processed unipolar charge transport and an emissive polymer that have an EQE of up to 1% at a brightness of 1350a €...cd/m 2, ON/OFF ratio > 10 4 and a well-defined light emitting zone suitable for display pixel design. We show that a non-planar hole-injecting electrode combined with a semi-transparent electron-injecting electrode enables to achieve high EQE at high brightness and high ON/OFF ratio. Furthermore, we demonstrate that heterostructure LEFETs have a better frequency response (f cut-off = 2.6a €...kHz) compared to single layer LEFETs the results presented here therefore are a major step along the pathway towards the realization of LEFETs for display applications.

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Exact N-wave solutions for the generalized Burgers equation u(t) + u(n)u(x) + (j/2t + alpha) u + (beta + gamma/x) u(n+1) = delta/2u(xx),where j, alpha, beta, and gamma are nonnegative constants and n is a positive integer, are obtained. These solutions are asymptotic to the (linear) old-age solution for large time and extend the validity of the latter so as to cover the entire time regime starting where the originally sharp shock has become sufficiently thick and the viscous effects are felt in the entire N wave.

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The unsteady incompressible viscous fluid flow between two parallel infinite disks which are located at a distance h(t*) at time t* has been studied. The upper disk moves towards the lower disk with velocity h'(t*). The lower disk is porous and rotates with angular velocity Omega(t*). A magnetic field B(t*) is applied perpendicular to the two disks. It has been found that the governing Navier-Stokes equations reduce to a set of ordinary differential equations if h(t*), a(t*) and B(t*) vary with time t* in a particular manner, i.e. h(t*) = H(1 - alpha t*)(1/2), Omega(t*) = Omega(0)(1 - alpha t*)(-1), B(t*) = B-0(1 - alpha t*)(-1/2). These ordinary differential equations have been solved numerically using a shooting method. For small Reynolds numbers, analytical solutions have been obtained using a regular perturbation technique. The effects of squeeze Reynolds numbers, Hartmann number and rotation of the disk on the flow pattern, normal force or load and torque have been studied in detail