Assessment and modelling of the viability of a solar heating system for aquatic centres in southern Australia

Aquatic centres are large users of energy for water and space heating with an energy intensity which can be up to seven times that of a commercial office building in Australia. Much of the energy is used to heat water to relatively low temperatures, and therefore, solar energy technology is capable of providing this energy. In the residential sector, solar thermal systems for heating water and swimming pools are well-established. This is not the case for commercial swimming pools i.e. aquatic centres. In Australia, a program to encourage commercial pool operators to install solar systems was funded in the early 1980s. This paper has investigated the current use of and attitudes to solar systems in commercial pools through a survey of municipal pool operators in Victoria, southern Australia. The survey found that there has been very little increase in the use of solar energy and that perceived barriers to the use of the technology remain the same as they were nearly 30 years ago. Lack of roof area, poor payback periods and an inability of solar to meet pool heating needs are the most common misconceptions. The paper investigates these misconceptions by analysing the hot water needs of a large aquatic centre in Melbourne. It was found that there was sufficient roof area to accommodate a solar system that would provide a solar fraction of 0.60 and the simple payback period for a solar system using unglazed solar collectors was approximately 6.7 years at current gas prices. These are predicted to rise significantly making solar energy an even more attractive proposition for commercial pool heating. Failure of past incentives to stimulate the uptake of solar pool heating systems necessitates a revised approach. Key stakeholders (industry bodies, local governments, pool operators, manufacturers, relevant HVAC consultants and research organisations) all need to be involved in an exemplar project to demonstrate the technology’s viability for aquatic centres.     

A review on front end conversion in ocean wave energy converters

Harvesting the energy from ocean waves is one of the greatest attractions for energy engineers and scientists. Till date, plenty of methods have been adopted to harvest the energy from the ocean waves. However, due to technological and economical complexity, it is intricate to involve the majority of these energy harvesters in the real ocean environment. Effective utilization and sustainability of any wave energy harvester depend upon its adaptability in the irregular seasonal waves, situation capability in maximum energy extraction and finally fulfilling the economic barriers. In this paper, the front end energy conversions are reviewed in detail which is positioned in the first stage of the wave energy converter among other stages such as power take off (PTO) and electrical energy conversion. If the recent development of these front end energy conversion is well known then developing wave energy converter with economic and commercial viability is possible. The aim of this review is to provide information on front end energy conversion of a point absorber and emphasize the strategies and calamity to be considered in designing such kinds of devices to improve the energy harvesting competence. This will be useful to the engineers for speeding up the development of a matured point absorbing type wave energy converter.     

2D and 3D mapping of microindentations in hydrated and dehydrated cortical bones using confocal laser scanning microscopy

We report on responses of hydrated and dehydrated cortical bone tissues to mechanical loading applied by a Vickers indenter. The Vickers indentations were imaged in two- and three-dimensions (2D and 3D) using confocal laser scanning microscopy (CLSM) to understand mechanical behavior of bone tissues. Serial optical sections of indentation patterns of dry and wet bones were collected using CLSM. The indention surface structures were mapped using topographical CLSM imaging. The observation of CLSM shows the fundamental indentation responses for both the hydrated and dehydrated bone tissues were plastic deformation. No visible fracture was observed in the Vickers indentation patterns in the wet bone tissue, while non-propagating lamellar microcracks occurred in the dry bone tissue. This indicates that drying resulted in increased brittleness of the bone tissue. The Vickers hardness values of dry bone tissue were significantly higher than those of wet bone tissue at any applied loads (analysis of variation, ANOVA, p < 0.05). The resolution limits of confocal microscopy were also discussed for bone tissue scanning.     

Integrated Framework for Quantifying and Predicting Weather-Related Highway Construction Delays

Constant exposure to the environment makes highway construction highly dependent on weather. However, highway construction contracts are often unclear about the potential influence of weather-related delays on highway construction project schedules. There is a need to discourage litigation arising from weather-related delays by including in contracts a reasonable number of nonwork days as a consequence of adverse weather and providing an equitable criteria for the course of action when the predictions in the contracts turn out to be inaccurate. To address this need, an integrated framework consisting of the following two key components is proposed: (1) identification of attributes of weather that cause construction delays and (2) generation of synthetic weather sequences using a stochastic weather generator to quantify and provide probabilistic forecasts of weather threshold values. The utility of this framework is demonstrated through its application to construction work on a project in Texas. The use of probabilistic forecast of construction delay attributes provided by a semiparametric weather generator in this research is an example of interdisciplinary study to help address this problem. The result of the research is better decision support for agencies who wish to author contracts that more equitably allow for the influence of weather during construction.     

In situ TEM study of microplasticity and Bauschinger effect in nanocrystalline metals

In situ transmission electron microscopy straining experiments with concurrent macroscopic stress–strain measurements were performed to study the effect of microstructural heterogeneity on the deformation behavior of nanocrystalline metal films. In microstructurally heterogeneous gold films (mean grain size d_m = 70 nm) comprising randomly oriented grains, dislocation activity is confined to relatively larger grains, with smaller grains deforming elastically, even at applied strains approaching 1.2%. This extended microplasticity leads to build-up of internal stresses, inducing a large Bauschinger effect during unloading. Microstructurally heterogeneous aluminum films (d_m = 140 nm) also show similar behavior. In contrast, microstructurally homogeneous aluminum films comprising mainly two grain families, both favorably oriented for dislocation glide, show limited microplastic deformation and minimal Bauschinger effect despite having a comparable mean grain size (d_m = 120 nm). A simple model is proposed to describe these observations. Overall, our results emphasize the need to consider both microstructural size and heterogeneity in modeling the mechanical behavior of nanocrystalline metals.     

Synthesis,characterization, and electrochemical performance of the ternary layered composite (1-x-y) LiNi1/3Co1/3Mn1/3O2·xLi2MnO3·yLiCoO2

Composite ceramic cathodes represented by the formula (1-x-y) LiNi_1/3Co_1/3Mn_1/3O₂·xLi₂MnO₃·yLiCoO₂ were studied. A ternary compositional diagram was built with these ceramic materials as end-members, and selected points were chosen to represent the compositional space. Synthesized ceramic composite materials were investigated as to whether integration of structurally compatible units leads to improved electrochemical performance. Detailed structural (X-ray diffraction – XRD), elemental (X-ray photoelectron spectroscopy-XPS), microstructure (Scanning electron microscopy – SEM), and electrochemical (galvanostatic testing of half-cells) studies were performed and are presented. Within eight samples studied three compositions are found to exhibit first discharge capacity of around 230 mAh/g.     

Hydrogen-iodide decomposition over PdCeO2 nanocatalyst for hydrogen production in sulfur-iodine thermochemical cycle

A highly active and stable catalyst for hydrogen-iodide decomposition reaction in sulfur-iodine (SI) cycle has been prepared in the form of PdCeO₂ nanocatalyst by sol-gel method with different calcination temperatures (300 °C, 500 °C, and 700 °C). XRD and TEM confirmed a size around 6–8 nm for PdCeO₂ particles calcined at 300 °C. Raman study revealed large number oxygen vacancies in PdCeO₂-300 when compared to PdCeO₂-500 and PdCeO₂-700. With increase in calcination temperature, the average particle size increased whereas the specific surface area and number of oxygen vacancies decreased. Hydrogen-iodide catalytic-decomposition was carried out in the temperature range of 400°C–550 °C in a quartz-tube, vertical, fixed-bed reactor with 55 wt % aqueous hydrogen-iodide feed over PdCeO₂ catalyst using nitrogen as a carrier gas. PdCeO₂-300 showed hydrogen-iodide conversion of 23.3%, which is close to the theoretical equilibrium conversion of 24%, at 550 °C. It also showed a reasonable stability with a time-on-stream of 5 h.     

Magnetic resonance scan‐time reduction using echo prediction

A linear prediction (LP) filter derived from a complete echo with zero‐phase encoding amplitude is used for recovering anatomical details from a partially acquired echo sequence. The LP filter is shown to reconstruct missing k‐space phase and amplitude information, with errors sufficiently low so as to provide image reconstruction with a contrast‐to‐noise ratio (CNR) ≥ 3. For volume imaging using multislice acquisition, the partial‐echo sequence enables more number of slices to be acquired for a given repetition time period T_R. For such sequences, separate predictors are used for reconstruction of missing k‐space data corresponding to each individual slice in the volume. The proposed filtering scheme is shown to achieve results comparable to other partial k‐space approaches such as singularity function analysis (SFA), when the noise content is less than about 0.4%. For higher noise levels, this technique is recommended as a preprocessing step for SFA to track the singularity locations more accurately. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 1–8, 2013     

Synthesis of phosphinic acid resin using acidic 1-butyl-3-methylimidazolium chloroaluminate ionic liquid as catalyst

The resin is functionalized by the introduction of phosphinic acid moieties by Friedel–Crafts phosphination reaction using acidic 1-butyl-3-methylimidazolium chloroaluminate ionic liquid as catalyst. The phosphorous and hydroxyl capacities of the resin are compared with those obtained by using conventional aluminium chloride catalysis. Extraction of uranium(VI) from nitric acid medium by the resins has been studied, and it was found that the distribution coefficient (K_d, mL/g) of uranium(VI) initially decreases with the increase in the concentration of nitric acid, and reaches a minimum value at 1.5 M in nitric acid followed by the increase in K_d values. A maximum distribution coefficient has been obtained when the concentration of nitric acid was 4.0–5.0 M. The extraction data have been fitted in to a Langmuir adsorption model for obtaining the apparent experimental capacity.     

Performance of a Binary PPM Ultra-Wideband Communication System with Direct Sequence Spreading for Multiple Access

In this paper, we present an analysis of the BER performance of an ultra-wideband (UWB) system with pulse position modulation (PPM) for data modulation and direct sequence (DS) spreading for multiple access over indoor lognormal fading channels. A rake receiver is used to combine a subset of the resolvable multipath components using the maximal ratio combining technique. Inter-path and multiple-access interferences are modeled and incorporated into the bit-error-rate expressions. The analytical and simulation results allow one to quantify many critical aspects of a DS-PPM UWB system such as the gain of the optimally spaced signaling scheme over the orthogonal signaling scheme, the potential error floor given a specific channel multipath delay spread and the number of interfering users, tolerance of the system to timing jitter, and impact of user codes.