Monitoring of Pressure Transients in Water Supply Networks

Ageing water infrastructure is one of the major problems faced by water utilities around the world at present, and urgent solutions are required in order to maintain the integrity of the water supply network. In order to use pipe failure prediction models, accurate information about loads acting on these pipes is important. Water pressure (steady-state and transient) is one of the key loads that needs to be estimated accurately in order to improve the predictability of pipe failures. This paper reports the results of a pressure monitoring program, which was conducted to measure pressure fluctuations during events of pressure transients in three selected network sections in Australia. Pressure measurements were conducted in network sections which were considered as susceptible to pressure transients. Potential sources of pressure transients were identified, and high speed data loggers were installed in selected locations of each network to measure and monitor pressure transients. Pressure transients that were generated during normal operation were measured for a period of one month in each selected section. Further, some of the pressure transients were manually made to simulate the different pressures due to pump start-ups within the network. Pressure fluctuations that could potentially lead to pipe failures were measured at many locations during the monitoring program (several selected failures were reported in this article). Therefore, the effect of pressure transients must not be ignored in pipe failure prediction.     

Modeling of Moisture Loss in Cementitiously Stabilized Pavement Materials

The paper presents a theoretical and experimental approach for the modeling of moisture loss during the drying of cementitiously stabilized pavement materials containing varying contents of fine-grained soil. The process of moisture loss was characterized by the isotropic nonlinear diffusion theory. Laboratory tests were undertaken using general purpose Portland cement and two binders comprising industrial waste products. Measurement of material characteristics included the coefficient of moisture diffusivity and the humidity isotherm. Locally available basaltic crushed rocks and clay were respectively used as the host pavement material and fine-grained soil. Independent laboratory tests were undertaken to validate the adopted theoretical approach, which showed close agreement between the experimental and predicted results. The laboratory results indicated that moisture loss decreased with the inclusion of clay soil within the mix. As the drying progressed, the rate of moisture loss became slower, which can be explained by the reduction in the coefficient of moisture diffusivity with the decrease of moisture content.     

Transport Properties of Bulk Thermoelectrics—An International Round-Robin Study, Part I: Seebeck Coefficient and Electrical Resistivity

Recent research and development of high-temperature thermoelectric materials has demonstrated great potential for converting automobile exhaust heat directly into electricity. Thermoelectrics based on classic bismuth telluride have also started to impact the automotive industry by enhancing air-conditioning efficiency and integrated cabin climate control. In addition to engineering challenges of making reliable and efficient devices to withstand thermal and mechanical cycling, the remaining issues in thermoelectric power generation and refrigeration are mostly materials related. The dimensionless figure of merit, ZT, still needs to be improved from the current value of 1.0 to 1.5 to above 2.0 to be competitive with other alternative technologies. In the meantime, the thermoelectric community could greatly benefit from the development of international test standards, improved test methods, and better characterization tools. Internationally, thermoelectrics have been recognized by many countries as a key component for improving energy efficiency. The International Energy Agency (IEA) group under the Implementing Agreement for Advanced Materials for Transportation (AMT) identified thermoelectric materials as an important area in 2009. This paper is part I of the international round-robin testing of transport properties of bulk thermoelectrics. The main foci in part I are the measurement of two electronic transport properties: Seebeck coefficient and electrical resistivity.     

Effects of static–fatigue (tension) on the tension–tension fatigue life of glass fibre reinforced plastic composites

The effects of static–fatigue interaction on tension–tension fatigue life of glass fibre reinforced plastic (GFRP) composites were investigated. This paper proposed a new static–fatigue model, which is capable of predicting residual strength after a period of static loading. Also an algorithm is proposed to calculate fatigue lives with the inclusion of static–fatigue interaction. Predictions from the proposed static–fatigue model show a good agreement with the experimental results. Static–fatigue interaction has shown a considerable effect on fatigue lives of GFRP composites at intermediate and lower applied stress levels possibly due to a longer exposure to applied loads. At higher load levels approximately greater than 65% of ultimate stress, and higher stress ratios range like 0.5 < R < 0.9, fatigue lives shown to be closer to material’s static–fatigue limits which is shorter than the expected lifetime by cyclic fatigue.     

Evaluation of engineering properties for the use of leached brown coal ash in soil covers

The need to engineer cover systems for the successful rehabilitation or remediation of a wide variety of solid wastes is increasing. Some common applications include landfills, hazardous waste repositories, or mine tailings dams and waste rock/overburden dumps. The brown coal industry of the Latrobe Valley region of Victoria, Australia, produces significant quantities of coal ash and overburden annually. There are some site-specific acid mine drainage (AMD) issues associated with overburden material. This needs to be addressed both during the operational phase of a project and during rehabilitation. An innovative approach was taken to investigate the potential to use leached brown coal ash in engineered soil covers on this overburden dump. The basis for this is two-fold: first, the ash has favourable physical characteristics for use in cover systems (such as high storage capacity/porosity, moderately low permeability, and an ability to act as a capillary break layer generating minimal leachate or seepage); and second, the leachate from the ash is mildly alkaline (which can help to mitigate and reduce the risk of AMD). This paper will review the engineering issues involved in using leached brown coal ash in designing soil covers for potentially acid-forming overburden dumps. It presents the results of laboratory work investigating the technical feasibility of using leached brown coal ash in engineered solid waste cover systems.