Non-linearities in the thermoacoustic response of a premixed swirl burner

PhDLean premixed combustion remains one of the simplest and most effective methods of reducing NOx emissions in industrial gas turbines. Lean premixed flames are however prone to an undesirable side effect known as combustion instability, reducing lifetime or in severe cases causing irreversible damage to the turbine. Previous studies on this subject mostly concentrated on the prediction and control of linear instabilities, whereas the current study pays particular attention to the non-linear response. In this work, scaled axial and radial swirl burners were used under atmospheric conditions to investigate the characteristics of the Flame Transfer Function (FTF) between the heat release from methane/air flames and the imposed velocity fluctuations. The velocity fluctuations imposed upon the air flow of the burners encompassed frequencies of 40 to 200 Hz, each with stepwise increase of velocity amplitude, until blow-off occurred. The work was carried out with non-intrusive, phase-locked optical diagnostic techniques, such as Particle Image Velocimetry (PIV) for flow field visualisation and an Intensified Charged Couple Device (ICCD) for analysis of the OH* chemiluminescent intensity distribution of the flame. It is concluded that there are two dominant mechanisms responsible for the non-linear response of the flame for both swirler geometries at low (below 140 Hz) and high (above 140 Hz) frequencies of excitation. At low frequencies the flame response is governed by equivalence ratio fluctuations due to the 'stiff' fuel system and volumetric fluctuations of the input air caused by the forcing. At high frequencies the flame response is governed by the flow features such as vortex roll-up, stretching the flame over the high speed annular jet, and in some cases, causing some flame extinction

Risk Management In Research And Development (R&d) Projects: The Case Of South Australia

A definition of the effective methods of risk management in R&D projects has remained elusive. Similarly, there have been calls to devise effective risk management methods in R&D projects. To develop this area further, the purpose of this study is twofold. First, it validates the veracity of claims about the urgency of introducing effective methods of risk management to R&D projects in South Australia based on nine unstructured interviews with experts. Second, the study presents the outcomes of two case studies that deployed the extended version of the failure mode and effect analysis, namely, the RFMEA method in a South Australian organisation, to investigate how the method can facilitate the identification of effective contingency plans to mitigate high-priority risks. The findings showed that the RFMEA method would be effective for project managers in dealing with risk management issues in R&D projects. The discussions presented will provide guidelines for practitioners in the industry

Investigating the Factors Associated with Job Satisfaction of Construction Workers in South Australia

The purpose of this paper is twofold. Firstly, its aim is to ascertain the major aspects of job satisfaction for South Australian construction workers including the main ramifications of job satisfaction in the working environment. Secondly, it investigates the influence of key age-related factors i.e. chronological age, organisational age and length of service on major aspects of job satisfaction. The collected data for this study comprised 72 questionnaires completed by construction practitioners working at operational levels in the South Australian construction industry. Based on the responses from the target group, this study deduced that job dissatisfaction was predominantly related to the adverse impact on personal health and quality of life. In addition, indifference and the perception of dejection in the workplace are the main consequences of low levels of job satisfaction. Inferential analyses revealed that none of the age-related factors could significantly affect the major aspects of job satisfaction of construction workers in the South Australian context. The study concludes with providing practical suggestions for redesigning human resources practices for increasing the level of job satisfaction within the South Australian construction industry.Keywords: Job satisfaction, workers, age, construction industry, South Australi

Critical success factors for implementing risk management systems in developing countries

A review of published studies on risk management in developing countries reveals that critical success factors for implementing risk management has remained an under-researched area of investigation. This paper is aimed at investigating the perceptions of construction professionals concerning the critical success factors (CSFs) for implementation of risk management systems (IRMS). Survey data was collected from 87 construction professionals from the Iranian construction industry as a developing country. The results indicate that four factors are regarded as highly critical: ‘support from managers’, ‘inclusion of risk management in construction education and training courses for construction practitioners’, ‘attempting to deliver projects systematically’, and ‘awareness and knowledge of the process for implementing risk management’. Assessing the associations among CSFs also highlighted the crucial role of enhancing the effectiveness of knowledge management practices in construction organisations. Study also revealed that parties involved in projects do not agree on the level of importance of CSFs for implementing risk management in developing countries. This study contributes to practice and research in several ways. For practice, it increases understanding of how closely knowledge management is associated with the implementation of risk management systems in developing countries. For research, the findings would encourage construction practitioners to support effective knowledge management as a precursor to higher levels of risk management implementation on construction projects

An investigation into using SAP-PS as a multidimensional project control system (MPCS)

This paper investigates the effectiveness of using a corporate enterprise resource planning (ERP) system as a multi-dimensional project control system (MPCS) to monitor and control the work performed on projects, meet the needs and expectations of the project managers and support the requirements of other key stakeholders. A qualitative approach i.e. case study interviews and literature review accompanied by a quantitative computer system validation test approach was deployed. The results from this study suggest that the corporate ERP system is effective at monitoring and controlling the project stakeholder success criteria within a fully integrated environment. The system does however need to be setup and configured for the purpose of MPCS. This study contributes to the field by providing empirical evidence that corporate ERP systems are likely one of the only systems truly capable of solving the age old problem of how to expand the traditional singular dimensional approaches commonly used in project control, thus multiple control dimensions are integrated with each other and other business systems to form a multi-dimensional project control system

Adopting global virtual engineering teams in AEC Projects: a qualitative meta-analysis of innovation diffusion studies

Purpose - This study aims to present an integrated conceptual model in order to highlight the major aspects of diffusion of innovations in the architecture, engineering and construction (AEC) context. To this end, a critical review of literature is conducted, accompaniedbysynthesising the findings of previous studies. The driving force behind this study is stemmed from the fragmentation of literature on innovation diffusion, and paucity of research on diffusion of Global Virtual Engineering Teams (GVETs) as the platform formany technological innovations in relevant literature. Thus, the present study is intended to facilitate filling the gap in GVETs literature. That is, the proposed model will offer a foundation for academia for grounding studies on any innovation including GVETs in the literature on innovation diffusion in the AEC context. Design/methodology/approach - This paper draws upon the qualitative meta-analysis approach encompassing a critical review of the relevant literature. To this end, the review builds upon studies found within 15 prestigious journals in AEC. The domain of this review was confined to areas described as "innovation", "innovation diffusion" and "innovation adoption", along with keywords used within a broad review of recently published GVETs literature. The rigour of review is augmented by incorporating 35 authoritative works from other disciplines published in 21 well-known journals in the manufacturing, business and management fields. Moreover, the study deploys the peer-debriefing approach through conducting unstructured interviews with five Australian scholars to verify a model presenting an aggregated summary of previous studies. Findings - The key findings of the study include the following items: Synthesising the fragmented studies on innovation diffusion in the AEC context. In doing so, a model capturing the major aspects affecting diffusion of an innovation in AEC projects is presented; providing a foundation to address the drawbacks of previous studies within the sphere of GVETs, based on the developed model. Research limitations/implications - The developed model was only enhanced using a small sample size of academics, as such not empirically validated. Originality/value - As possibly, the first literature review of innovation in the AEC context, this paper contributes to the sphere by sensitising the AEC body of knowledge on innovation diffusion as a concise conceptual model, albeit verified through the peer-debriefing approach. This study will also further establish the research field in AEC on GVETs along with other methods reliant on virtual working such as building information modelling (BIM) through providing an expanded foundation for future inquiries and creation of knowledge

Investigating the Influence of Penetration Length of Cut-off Wall on its Dynamic Interaction with Core and Foundation of Earth Dam

Seepage and flow of water in the soil is one of the most important issue and effective elements in designing embankment dams. One of the methods to control seepage in alluvial foundation of earth dams is to use a plastic concrete cutoff-wall. For better seepage control, the cutoff-wall extends inside the clayey core as the one of common method of connection of cut-off wall and the core. Due to the stiffness difference of the core material and cutoff-wall, and also due to geological situation, physical and mechanical properties of rock and foundation, interaction of core and foundation with cut-off wall in different static and dynamic load cases is very considerable. Failure of cut-off wall occurs in cut-off wall and core joint.  So the study of their interaction, especially during an earthquake is very important. Karkheh dam cut-off wall with an area of about 150000 m2 is chosen for this study. FLAC software has been used to study the effect of cutoff-wall penetration length variation, inside the clay core of Karkheh earth dam under dynamic loading.  In numerical analysis of Karkheh earth dam model, all construction stages and seepage through dam are modelled. The model is first calibrated according to the results obtained from the dam instrumentations. After calibrating, according to available seismic studies of region, a suitable acceleration was selected and applied to the model. In this research, in order to find the optimum length, the effect of 0, 5, 10, 15 and 20 meters penetration length of cut-off wall in aforementioned conditions has been investigated. The results of the numerical study showed that the horizontal displacement and the maximum shear strain in the cutoff-wall is occurred adjacent to the clay core and the interface of core and foundation is a critical point for the cut-off wall, and also the stress in cut off wall joint increases with the elongation of penetration depth of the wall