Temperature homogeneity in most food refrigeration systems is directly governed by the airflow patterns in the system. Numerical modelling of airflow provides an opportunity to develop improved ...understanding of the underlying phenomena influencing system performance, which can lead to reduced temperature heterogeneity and increased effectiveness and efficiency of refrigeration systems. With the rapid advances in computational power of recent years, the use of Computational Fluid Dynamics (CFD) techniques in this application has become popular. This paper reviews the application of CFD and other numerical modelling techniques to the prediction of airflow in refrigerated food applications including cool stores, transport equipments and retail display cabinets.
Optimal storage conditions for apples are usually defined as those that maximise possible storage duration, but could be redefined as those conditions that result in sufficient preservation whilst ...minimising energy costs. A review of research on controlled atmosphere (CA) storage suggests that temperature changes in CA have less impact on product deterioration than in air. This paper reviews the underpinning observations of fruit physiology in CA and the possible approaches to reducing energy costs through temperature manipulation. Experimental results indicate that minor increases in temperature during CA storage have little influence on apple quality outcomes across a number of apple cultivars. Calculations for applying a 9 h on 15 h off cycle estimated an approximate 40% of electricity cost savings whilst only incurring a 0.5 °C average fruit temperature swing. These results suggest that opportunities for substantial energy cost savings in controlled atmosphere apple stores exist.
► Potential rewards and risks of load shifting during apple storage are quantified. ► Temperature changes in controlled atmosphere had little impact on apple quality. ► Load shifting in a commercial room resulted in a temperature oscillation of ±1 °C. ► A 40% energy cost saving may be possible with a 0.5 °C temperature oscillation. ► Load shifting of controlled atmosphere stores to save energy costs seems viable.
Summary Temperature sensitive products are often transported in non-refrigerated systems, protected from environmental temperatures by thermal insulation and the provision of a source of cold inside ...the package. This work presents a method for optimising the design of thermally insulated boxes for lowest cost (while ensuring that product temperatures are maintained within set limits) by combining a heat transfer model with genetic algorithm optimisation. An example optimisation problem is presented in which a temperature sensitive product is transported across the US and must be maintained between −1 and 8 °C. Independent optimisation operations successfully identified solutions that were very similar, though not identical, thereby providing confidence in the approach to determine optimal solutions to complex problems. The system developed provides a rapid method to optimise the design of an insulated box for minimum cost while maintaining the product in the appropriate temperature range.
The aim of this study was to estimate random match frequency of randomly acquired characteristics (RAC-RMF) for laboratory-simulated crime scene impressions. Part I of this investigation reports this ...metric using a dataset of more than 160 questioned impressions created in blood and deposited on tile. A total of 759 RACs were identified in the blood impressions and compared to RACs with positional similarity in test impressions from 1,299 unrelated outsoles. Geometric similarity was quantified using a combination of visual comparisons and mathematical modeling based on percent area overlap. Results indicated that RACs in blood impressions were typically smaller, and therefore exhibited a two-thirds increase in the number of indistinguishable pairs compared to their mated test impressions. For shoes contributing at least one RAC, relative RAC-RMF values ⩾ 0.0008 were encountered at a rate between 3.4% and 34% for the blood impressions examined in this study. Part II of this investigation provides analogous results based on dust impressions deposited on paper and tile. Although the results in Part I and Part II are specific to randomly acquired characteristics and do not translate into an impression-wide RMF estimate, this research shows that RACs in questioned impressions of the type expected in casework co-occur in position and geometry with RACs in non-mated test impressions. Since theoretical models have traditionally been the basis for estimating RAC-RMF in footwear, the overall contribution of this research to the forensic footwear community is a calibration of this estimate based on empirical data.
This study serves as Part II of an investigation into the random match frequency of randomly acquired characteristics (RAC-RMF) in footwear evidence. In Part I, RAC-RMF was estimated in a dataset of ...laboratory-simulated crime scene impressions deposited in blood. For Part II, a second dataset was created composed of impressions deposited in dust on paper or tile, with the latter lifted using gelatin or Mylar film. A total of 1,513 RACs were identified from more than 160 dust impressions and compared to RACs with positional similarity in test impressions from 1,299 non-mated outsoles. RACs of any size deposited in dust exhibited a 31% decrease in shoes with non-zero RAC-RMFs as compared to their mated test impressions, while those deposited in blood exhibited a 45% increase. When only considering shoes with at least one RAC deemed forensically-reliable (length ⩾ 2.8 mm), 3.1% of shoes contributing dust impressions and 3.4% of shoes contributing blood impressions exhibited relative RAC-RMFs at a value ⩾ 0.0008. Although each dataset resulted in a comparable rate for encountering non-zero RAC-RMFs, the estimate for dust was based on twice the number of RAC comparisons (154,477) than those performed when assessing blood (77,566). While these results are considered specific to the non-mated impressions and methods of analysis described herein, and continued work is required before rates can be fully understood and reported in forensic casework, this study encountered non-zero RAC-RMFs for shoes exhibiting at least one forensically-reliable RAC at a more frequent rate than any estimates previously reported.
•Randomly acquired characteristics (RACs) were compared on unrelated outsoles.•2,181 RAC pairs with positional and geometric similarity exist on 1,300 outsoles.•Random match frequency values ranged ...from 0 out of 1,299 to 49 out of 1,299.•32% of outsoles did not share any indistinguishable RACs with another outsole.•Up to five indistinguishable pairs were shared between two unrelated outsoles.
When analyzing footwear impression evidence, a significant task of the forensic examiner is to determine if a questioned impression could have originated from a known shoe. To form this opinion, examiners typically evaluate the similarity, quantity, and quality of shared class characteristics and characteristics of use. Since these criteria are developed through training and experience, and therefore purported to be subjective in nature, the opinions formed regarding footwear evidence can be misunderstood. One way to mitigate this criticism is to complement casework with research that includes quantitative analyses. The aim of this study was to estimate random match frequency of randomly acquired characteristics (RAC-RMF) in a research database comprised of 1,300 outsoles with more than 80,000 RACs. Based on a combination of visual comparisons (>91,000) and mathematical predictions (>3.8 million), results indicate that 32% of the outsoles in this dataset do not share any indistinguishable RAC pairs with each other, while 19% possess RAC-RMFs of 1 out of 1,299. At the other extreme, the maximum RAC-RMF observed was 49 out of 1,299. These results are based on high-quality test impressions, human assessments, and a single quantitative similarity metric, so they are considered specific to this dataset and method of analysis. Results could differ in other databases and with impressions of lower quality, and therefore should not be extrapolated to casework. Despite this limitation, the results provide a point of reference for how often RACs may repeat in position and geometry on non-mated outsoles, therefore forming the basis for future research.
The domestic transport of low volume perishable products is commonly conducted with the use of insulated boxes and non-refrigerated commercial courier networks. The temperature of the product during ...transport is governed by the balance of the environmental temperature and the protection provided by the box's insulation and accompanying coolant (e.g. ice). While the box, product and coolant properties may be constant, the ability of that package to maintain appropriate product temperatures will be different due to the day-to-day variation in environmental conditions. This paper presents a method that uses historic climatic data to estimate environmental temperatures during transport and subsequently provides a quantitative estimate of the likelihood of package temperature control failure. Three packages travelling by road from Sydney to Melbourne are compared as an example of the use of the methodology.
Ecological studies often suggest that natural grasslands with high species diversity will grow more biomass and leach less nitrogen (N). If this diversity effect also applies to fertilised and ...irrigated pastures with controlled removal of herbage, it might be exploited to design pastures that can assist the dairy industry to maintain production while reducing N leaching losses. The purpose of this study was to test whether pasture mixtures with a high functional diversity in ryegrass traits will confer on the system higher water- and N-use efficiency. The hypothesis was tested using a process-based model in which pasture mixtures were created with varying levels of diversity in ryegrass traits likely to affect pasture growth. Those traits were: the winter- or summer-dominance of growth, the ability of the plant to intercept radiation at low pasture mass, and rooting depth. Pasture production, leaching and water- and N-use efficiency were simulated for management typical of a dairy pasture. We found that the performance of the diverse ryegrass–clover mixtures was more strongly associated with the performance of the individual components than with the diversity across the components. Diverse pasture mixtures may confer other benefits, e.g. pest or disease resistance and pasture persistence. The testing here was within a selection of ryegrasses, and the greater possible diversity across species may produce different effects. However, these results suggest that highly performing pastures under fertilised and irrigated grazed conditions are best constructed by selecting components that perform well individually than by deliberately introducing diversity between components.
To successfully manage food safety and quality risks in meat production, a holistic approach is required. The ideal would be a fully integrated assurance system, with effective controls applied at ...all stages. However, the red meat industry is by nature somewhat fragmented, and a truly integrated system is not at present achievable in all but a few operations. This paper describes a variety of assurance initiatives, and explores how targeted research and development can be used to augment assurance programmes by providing underpinning knowledge, using the Australian beef and lamb industry as an example.
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