14 resultados para Equations of state

em Queensland University of Technology - ePrints Archive


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Troubled dynamics between residents of an Aboriginal town in Queensland and the local health system were established during colonisation and consolidated during those periods of Australian history where the policies of 'protection' (segregation), integration and then assimilation held sway. The status of Aboriginal health is, in part, related to interactions between the residents' current and historical experiences of the health and criminal justice systems as together these agencies used medical and moral policing to legitimate dispossession, marginalisation, institutionalisation and control of the residents. The punitive regulations and ethnocentric strategies used by these institutions are within the living memory of many of the residents or in the published accounts of preceding generations. This paper explores current residents' memories and experiences.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Optimisation of Organic Rankine Cycles (ORCs) for binary cycle applications could play a major role in determining the competitiveness of low to moderate renewable sources. An important aspect of the optimisation is to maximise the turbine output power for a given resource. This requires careful attention to the turbine design notably through numerical simulations. Challenges in the numerical modelling of radial-inflow turbines using high-density working fluids still need to be addressed in order to improve the turbine design and better optimise ORCs. This paper presents preliminary 3D numerical simulations of a radial-inflow turbine working with high-density fluids in realistic geothermal ORCs. Following extensive investigation of the operating conditions and thermodynamic cycle analysis, the refrigerant R143a is chosen as the high-density working fluid. The 1D design of the candidate radial-inflow turbine is presented in details. Furthermore, commercially-available software Ansys-CFX is used to perform the 3D CFD simulations for a number of operating conditions including off-design conditions. The real-gas properties are obtained using the Peng-Robinson equations of state. The preliminary design created using dedicated radial-inflow turbine software Concepts-Rital is discussed and the 3D CFD results are presented and compared against the meanline analysis.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Optimisation of organic Rankine cycles(ORCs for binary cycle applications could play a major role in determining the competitiveness of low to moderate renewable sources. An important aspect of the optimisation is to maximise the turbine output power for a given resource. This requires careful attention to the turbine design notably through numerical simulations. Challenges in the numerical modelling of radial-inflow turbines using high-density working fluids still need to be addressed in order to improve the turbine design and better optimise ORCs. Thispaper presents preliminary 3D numerical simulations of a high-density radial-inflow ORC turbine in sensible geothermal conditions. Following extensive investigation of the operating conditions and thermodynamic cycle analysis, therefrigerant R143a is chosen as the high-density working fluid. The 1D design of the candidate radial-inflow turbine is presented in details. Furthermore, commercially-available software Ansys-CFX is used to perform preliminary steady-state 3D CFD simulations of the candidate R143a radial-inflow turbine for a number of operating conditions including off-design conditions. The real-gas properties are obtained using the Peng–Robinson equations of state.The thermodynamic ORC cycle is presented. The preliminary design created using dedicated radial-inflow turbine software Concepts-Rital is discussed and the 3D CFD results are presented and compared against the meanline analysis.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Since the 1980s the concept of risk has produced a large and diverse volume of sociological research. Ulrich Beck’s groundbreaking risk society thesis provides a particularly engaging contribution, since it seems that nearly every sociological account of risk engages with this work. For Beck, we are living in second modernity – a new epoch that breaks with pre-modernity and industrial society due to the centrality, incalculability and reflexivity of globalised risk. While Beck’s theory is compelling, a reading of other theorists such as Foucault (2007[1978]) and Hacking (1975,1990) suggests that a difficulty with Beck’s work is that in attempting to explain what is novel about risk in contemporary times, he too quickly passes over the complexities and ruptures of historical change that impact on the history and contingency of risk. This paper begins by presenting a brief analysis of the present state of risk by introducing Beck’s historical narrative of risk from pre-modernity to the risk society; it then outlines the challenges with the “risk as epoch” argument by considering a range of literature, which suggests risk has a more complex history than proposed by Beck; and finally it highlights the value in examining strategies of statecraft in early modern Europe, specifically Machiavelli’s The Prince (2008[1513]) and Giovanni Botero’s political treatise, Della Ragion di Stato (1956[1589]) – as a means of more thoroughly understanding how our current concept of risk emerges. In doing so, this paper seeks to open up new trajectories in the historicisation of risk for other interested scholars.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Construction projects can involve a diverse range of stakeholders and the success of the project depends very much on fulfilling their needs and expectations. It is important, therefore, to identify and recognize project stakeholders and develop a rigorous stakeholder management process. However, limited research has investigated the impact of stakeholders on construction projects in developing countries. A stakeholder impact analysis (SIA), based on an approach developed by Olander (2007), was adopted to investigate the stakeholders' impact on state-owned civil engineering projects in Vietnam. This involved the analysis of a questionnaire survey of 57 project managers to determine the relative importance of different stakeholders. The results show the client to have the highest level of impact on the projects, followed by project managers and the senior management of state-owned engineering firms. The SIA also provides suggestions to project managers in developing and evaluating the stakeholder management process.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Purpose, Design/methodology / approach The acknowledgement of state significance in relation to development projects can result in special treatment by regulatory authorities, particularly in terms of environmental compliance and certain economic and other government support measures. However, defining just what constitutes a “significant project”, or a project ofstate significance”, varies considerably between Australian states. In terms of establishing threshold levels, in Queensland there is even less clarity. Despite this lack of definition, the implications ofstate significance” can nevertheless be considerable. For example, in Queensland if the Coordinator-General declares a project to be a “significant project” under the State Development and Public Works Organisation Act 1971, the environmental impact assessment process may become more streamlined – potentially circumventing certain provisions under The Integrated Planning Act 1997. If the project is not large enough to be so deemed, an extractive resource under the State Planning Policy 2/07 - Protection of Extractive Resources 2007 may be considered to be of State or regional significance and subsequently designated as a “Key Resource Area”. As a consequence, such a project is afforded some measure of resource protection but remains subject to the normal assessment process under the Integrated Development Assessment System, as well as the usual requirements of the vegetation management codes, and other regulations. Findings (Originality/value) & Research limitations / implications This paper explores the various meanings ofstate significance” in Queensland and the ramifications for development projects in that state. It argues for a streamlining of the assessment process in order to avoid or minimise constraints acting on the state’s development. In so doing, it questions the existence of a strategic threat to the delivery of an already over-stretched infrastructure program.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Efficient state asset management is crucial for governments as they facilitate the fulfillment of their public functions, which include the provision of essential services and other public administration support. In recent times economies internationally and particularly in South east Asia, have displayed increased recognition of the importance of efficiencies across state asset management law, policies and practice. This has been exemplified by a surge in notable instances of reform in state asset management. A prominent theme in this phenomenon is the consideration of governance principles within the re-conceptualization of state asset management law and related policy, with many countries recognizing variability in the quality of asset governance and opportunities for profit as being critical factors. This issue is very current in Indonesia where a major reform process in this area has been confirmed by the establishment of a new Directorate of State Asset Management. The incumbent Director-General of State Asset Management has confirmed a re-emphasis on adherence to governance principles within applicable state asset management law and policy reform. This paper reviews aspects of the challenge of reviewing and reforming Indonesian practice within state asset management law and policy specifically related to public housing, public buildings, parklands, and vacant land. A critical issue in beginning this review is how Indonesia currently conceptualizes the notion of asset governance and how this meaning is embodied in recent changes in law and policy and importantly in options for future change. This paper discusses the potential complexities uniquely Indonesian characteristics such as decentralisation and regional autonomy regime, political history, and bureaucratic culture

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Biochemical reactions underlying genetic regulation are often modelled as a continuous-time, discrete-state, Markov process, and the evolution of the associated probability density is described by the so-called chemical master equation (CME). However the CME is typically difficult to solve, since the state-space involved can be very large or even countably infinite. Recently a finite state projection method (FSP) that truncates the state-space was suggested and shown to be effective in an example of a model of the Pap-pili epigenetic switch. However in this example, both the model and the final time at which the solution was computed, were relatively small. Presented here is a Krylov FSP algorithm based on a combination of state-space truncation and inexact matrix-vector product routines. This allows larger-scale models to be studied and solutions for larger final times to be computed in a realistic execution time. Additionally the new method computes the solution at intermediate times at virtually no extra cost, since it is derived from Krylov-type methods for computing matrix exponentials. For the purpose of comparison the new algorithm is applied to the model of the Pap-pili epigenetic switch, where the original FSP was first demonstrated. Also the method is applied to a more sophisticated model of regulated transcription. Numerical results indicate that the new approach is significantly faster and extendable to larger biological models.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Efficient state asset management is crucial for governments as they facilitate the fulfillment of their public functions, which include the provision of essential services and other public administration support. In recent times economies internationally and particularly in South east Asia, have displayed increased recognition of the importance of efficiencies across state asset management law, policies and practice. This has been exemplified by a surge in notable instances of reform in state asset management. A prominent theme in this phenomenon is the consideration of governance principles within the re-conceptualization of state asset management law and related policy, with many countries recognizing variability in the quality of asset governance and opportunities for profit as being critical factors. This issue is very current in Indonesia where a major reform process in this area has been confirmed by the establishment of a new Directorate of State Asset Management. The incumbent Director-General of State Asset Management has confirmed a re-emphasis on adherence to governance principles within applicable state asset management law and policy reform. This paper reviews aspects of the challenge of reviewing and reforming Indonesian practice within state asset management law and policy specifically related to public housing, public buildings, parklands, and vacant land. A critical issue in beginning this review is how Indonesia currently conceptualizes the notion of asset governance and how this meaning is embodied in recent changes in law and policy and importantly in options for future change. This paper discusses the potential complexities uniquely Indonesian characteristics such as decentralisation and regional autonomy regime, political history, and bureaucratic culture.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Streamciphers are common cryptographic algorithms used to protect the confidentiality of frame-based communications like mobile phone conversations and Internet traffic. Streamciphers are ideal cryptographic algorithms to encrypt these types of traffic as they have the potential to encrypt them quickly and securely, and have low error propagation. The main objective of this thesis is to determine whether structural features of keystream generators affect the security provided by stream ciphers.These structural features pertain to the state-update and output functions used in keystream generators. Using linear sequences as keystream to encrypt messages is known to be insecure. Modern keystream generators use nonlinear sequences as keystream.The nonlinearity can be introduced through a keystream generator's state-update function, output function, or both. The first contribution of this thesis relates to nonlinear sequences produced by the well-known Trivium stream cipher. Trivium is one of the stream ciphers selected in a final portfolio resulting from a multi-year project in Europe called the ecrypt project. Trivium's structural simplicity makes it a popular cipher to cryptanalyse, but to date, there are no attacks in the public literature which are faster than exhaustive keysearch. Algebraic analyses are performed on the Trivium stream cipher, which uses a nonlinear state-update and linear output function to produce keystream. Two algebraic investigations are performed: an examination of the sliding property in the initialisation process and algebraic analyses of Trivium-like streamciphers using a combination of the algebraic techniques previously applied separately by Berbain et al. and Raddum. For certain iterations of Trivium's state-update function, we examine the sets of slid pairs, looking particularly to form chains of slid pairs. No chains exist for a small number of iterations.This has implications for the period of keystreams produced by Trivium. Secondly, using our combination of the methods of Berbain et al. and Raddum, we analysed Trivium-like ciphers and improved on previous on previous analysis with regards to forming systems of equations on these ciphers. Using these new systems of equations, we were able to successfully recover the initial state of Bivium-A.The attack complexity for Bivium-B and Trivium were, however, worse than exhaustive keysearch. We also show that the selection of stages which are used as input to the output function and the size of registers which are used in the construction of the system of equations affect the success of the attack. The second contribution of this thesis is the examination of state convergence. State convergence is an undesirable characteristic in keystream generators for stream ciphers, as it implies that the effective session key size of the stream cipher is smaller than the designers intended. We identify methods which can be used to detect state convergence. As a case study, theMixer streamcipher, which uses nonlinear state-update and output functions to produce keystream, is analysed. Mixer is found to suffer from state convergence as the state-update function used in its initialisation process is not one-to-one. A discussion of several other streamciphers which are known to suffer from state convergence is given. From our analysis of these stream ciphers, three mechanisms which can cause state convergence are identified.The effect state convergence can have on stream cipher cryptanalysis is examined. We show that state convergence can have a positive effect if the goal of the attacker is to recover the initial state of the keystream generator. The third contribution of this thesis is the examination of the distributions of bit patterns in the sequences produced by nonlinear filter generators (NLFGs) and linearly filtered nonlinear feedback shift registers. We show that the selection of stages used as input to a keystream generator's output function can affect the distribution of bit patterns in sequences produced by these keystreamgenerators, and that the effect differs for nonlinear filter generators and linearly filtered nonlinear feedback shift registers. In the case of NLFGs, the keystream sequences produced when the output functions take inputs from consecutive register stages are less uniform than sequences produced by NLFGs whose output functions take inputs from unevenly spaced register stages. The opposite is true for keystream sequences produced by linearly filtered nonlinear feedback shift registers.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Railway is one of the most important, reliable and widely used means of transportation, carrying freight, passengers, minerals, grains, etc. Thus, research on railway tracks is extremely important for the development of railway engineering and technologies. The safe operation of a railway track is based on the railway track structure that includes rails, fasteners, pads, sleepers, ballast, subballast and formation. Sleepers are very important components of the entire structure and may be made of timber, concrete, steel or synthetic materials. Concrete sleepers were first installed around the middle of last century and currently are installed in great numbers around the world. Consequently, the design of concrete sleepers has a direct impact on the safe operation of railways. The "permissible stress" method is currently most commonly used to design sleepers. However, the permissible stress principle does not consider the ultimate strength of materials, probabilities of actual loads, and the risks associated with failure, all of which could lead to the conclusion of cost-ineffectiveness and over design of current prestressed concrete sleepers. Recently the limit states design method, which appeared in the last century and has been already applied in the design of buildings, bridges, etc, is proposed as a better method for the design of prestressed concrete sleepers. The limit states design has significant advantages compared to the permissible stress design, such as the utilisation of the full strength of the member, and a rational analysis of the probabilities related to sleeper strength and applied loads. This research aims to apply the ultimate limit states design to the prestressed concrete sleeper, namely to obtain the load factors of both static and dynamic loads for the ultimate limit states design equations. However, the sleepers in rail tracks require different safety levels for different types of tracks, which mean the different types of tracks have different load factors of limit states design equations. Therefore, the core tasks of this research are to find the load factors of the static component and dynamic component of loads on track and the strength reduction factor of the sleeper bending strength for the ultimate limit states design equations for four main types of tracks, i.e., heavy haul, freight, medium speed passenger and high speed passenger tracks. To find those factors, the multiple samples of static loads, dynamic loads and their distributions are needed. In the four types of tracks, the heavy haul track has the measured data from Braeside Line (A heavy haul line in Central Queensland), and the distributions of both static and dynamic loads can be found from these data. The other three types of tracks have no measured data from sites and the experimental data are hardly available. In order to generate the data samples and obtain their distributions, the computer based simulations were employed and assumed the wheel-track impacts as induced by different sizes of wheel flats. A valid simulation package named DTrack was firstly employed to generate the dynamic loads for the freight and medium speed passenger tracks. However, DTrack is only valid for the tracks which carry low or medium speed vehicles. Therefore, a 3-D finite element (FE) model was then established for the wheel-track impact analysis of the high speed track. This FE model has been validated by comparing its simulation results with the DTrack simulation results, and with the results from traditional theoretical calculations based on the case of heavy haul track. Furthermore, the dynamic load data of the high speed track were obtained from the FE model and the distributions of both static and dynamic loads were extracted accordingly. All derived distributions of loads were fitted by appropriate functions. Through extrapolating those distributions, the important parameters of distributions for the static load induced sleeper bending moment and the extreme wheel-rail impact force induced sleeper dynamic bending moments and finally, the load factors, were obtained. Eventually, the load factors were obtained by the limit states design calibration based on reliability analyses with the derived distributions. After that, a sensitivity analysis was performed and the reliability of the achieved limit states design equations was confirmed. It has been found that the limit states design can be effectively applied to railway concrete sleepers. This research significantly contributes to railway engineering and the track safety area. It helps to decrease the failure and risks of track structure and accidents; better determines the load range for existing sleepers in track; better rates the strength of concrete sleepers to support bigger impact and loads on railway track; increases the reliability of the concrete sleepers and hugely saves investments on railway industries. Based on this research, many other bodies of research can be promoted in the future. Firstly, it has been found that the 3-D FE model is suitable for the study of track loadings and track structure vibrations. Secondly, the equations for serviceability and damageability limit states can be developed based on the concepts of limit states design equations of concrete sleepers obtained in this research, which are for the ultimate limit states.