Gas boosted solar water heaters : Queensland case studies of installation practices in new homes

Because of the greenhouse gas emissions implications of the market dominating electric hot water systems, governments in Australia have implemented policies and programs to encourage the uptake of solar water heaters (SWHs) in the residential market as part of climate change adaptation and mitigation strategies. The cost-benefit analysis that usually accompanies all government policy and program design could be simplistically reduced to the ratio of expected greenhouse gas reductions of SWH to the cost of a SWH. The national Register of Solar Water Heaters specifies how many renewable energy certificates (RECs) are allocated to complying SWHs according to their expected performance, and hence greenhouse gas reductions, in different climates. Neither REC allocations nor rebates are tied to actual performance of systems. This paper examines the performance of instantaneous gas-boosted solar water heaters installed in new residences in a housing estate in south-east Queensland in the period 2007 – 2010. The evidence indicates systemic failures in installation practices, resulting in zero solar performance or dramatic underperformance (estimated average 43% solar contribution). The paper will detail the faults identified, and how these faults were eventually diagnosed and corrected. The impacts of these system failures on end-use consumers are discussed before concluding with a brief overview of areas where further research is required in order to more fully understand whole of supply chain implications.

Thermal studies of D.C. traction motors

This paper describes a thorough thermal study on a fleet of DC traction motors which were found to suffer from overheating after 3 years of full operation. Overheating of these traction motors is attributed partly because of the higher than expected number of starts and stops between train terminals. Another probable cause of overheating is the design of the traction motor and/or its control strategy. According to the motor manufacturer, a current shunt is permanently connected across the motor field winding. Hence, some of the armature current is bypassed into the current shunt. The motor then runs above its rated speed in the field weakening mode. In this study, a finite difference model has been developed to simulate the temperature profile at different parts inside the traction motor. In order to validate the simulation result, an empty vehicle loaded with drums of water was also used to simulate the full pay-load of a light rail vehicle experimentally. The authors report that the simulation results agree reasonably well with experimental data, and it is likely that the armature of the traction motor will run cooler if its field shunt is disconnected at low speeds

Panel studies of new venture creation : a review and suggestions for future research

We review all journal articles based on “PSED-type” research, i.e., longitudinal, empirical studies of large probability samples of on-going, business start-up efforts. We conclude that the research stream has yielded interesting findings; sometimes by confirming prior research with a less bias-prone methodology and at other times by challenging whether prior conclusions are valid for the early stages of venture development. Most importantly, the research has addressed new, process-related research questions that prior research has shunned or been unable to study in a rigorous manner. The research has revealed an enormous and fascinating variability in new venture creation that also makes it challenging to arrive at broadly valid generalizations. An analysis of the findings across studies as well as an examination of those studies that have been relatively more successful at explaining outcomes give good guidance regarding what is required in order to achieve strong and credible results. We compile and present such advice to users of existing data sets and designers of new projects in the following areas: Statistically representative and/or theoretically relevant sampling; Level of analysis issues; Dealing with process heterogeneity; Dealing with other heterogeneity issues, and Choice and interpretation of dependent variables.

Building bridges to participation : sociocultural case studies of AfL

Assessment for Learning(AfL) case studies in a North Queensland school highlight the significance of the teacher-student relationship in creating a supportive culture within which students can negotiate new learner identities. AfL practices are school based evaluative practices that occur within the regular flow of teaching and learning with the purpose of informing and improving student learning to enhance learner autonomy. The identity of an autonomous learner is socially negotiated through participation in the community of practice of the class. Underpinned by a sociocultural perspective this research shows how AfL is manifested in action in its complexity and how positive teacher-student interactions can build bridges for students to move towards full participation.

Panel studies of new venture creation: a methods-focused review and suggestions for future research

Longitudinal panel studies of large, random samples of business start-ups captured at the pre-operational stage allow researchers to address core issues for entrepreneurship research, namely, the processes of creation of new business ventures as well as their antecedents and outcomes. Here, we perform a methods-orientated review of all 83 journal articles that have used this type of data set, our purpose being to assist users of current data sets as well as designers of new projects in making the best use of this innovative research approach. Our review reveals a number of methods issues that are largely particular to this type of research. We conclude that amidst exemplary contributions, much of the reviewed research has not adequately managed these methods challenges, nor has it made use of the full potential of this new research approach. Specifically, we identify and suggest remedies for context-specific and interrelated methods challenges relating to sample definition, choice of level of analysis, operationalization and conceptualization, use of longitudinal data and dealing with various types of problematic heterogeneity. In addition, we note that future research can make further strides towards full utilization of the advantages of the research approach through better matching (from either direction) between theories and the phenomena captured in the data, and by addressing some under-explored research questions for which the approach may be particularly fruitful.