Evaluation of the Techniques to Mitigate Early Shrinkage Cracking through an Image Analysis Methodology

Nowadays, new products are introduced in concrete mixes to reduce the effects of shrinkage, which are the main reason of most of early age cracking phenomena, especially when curing is not performed in accordance to best practices. The lack of a standardized methodology to quantify concrete cracking complicates the determination of the effectiveness of different solutions and comparison between them. This research presents an evaluation through images of the suitability of fibres and shrinkage‐reducing admixtures to control early shrinkage cracking in slab‐type concrete elements. The use of this technique has permitted quantifying the typical cracking parameters objectively and analyse probabilistically the average crack width. Results show a delay and reduction of cracking after adding shrinkage‐reducing admixtures and fibres in concrete, especially 1 kg m^?3 of polymeric microfibres. The incorporation of these components directly into the mix modified the behaviour of concrete, reducing shrinkage cracking from the beginning of moisture losses.     

Experimental determination of photon propagation in highly absorbing and scattering media

Optical imaging and tomography in tissues can facilitate the quantitative study of several important chromophores and fluorophores. Several theoretical models have been validated for diffuse photon propagation in highly scattering and low-absorbing media that describe the optical appearance of tissues in the near-infrared (NIR) region. However, these models are not generally applicable to quantitative optical investigations in the visible because of the significantly higher tissue absorption in this spectral region compared with that in the NIR. We performed photon measurements through highly scattering and absorbing media for ratios of the absorption coefficient to the reduced scattering coefficient ranging approximately from zero to one. We examined experimentally the performance of the absorption-dependent diffusion coefficient defined by Aronson and Corngold [J. Opt. Soc. Am. A 16, 1066 (1999)] for quantitative estimations of photon propagation in the low- and high-absorption regimes. Through steady-state measurements we verified that the transmitted intensity is well described by the diffusion equation by considering a modified diffusion coefficient with a nonlinear dependence on the absorption. This study confirms that simple analytical solutions based on the diffusion approximation are suitable even for high-absorption regimes and shows that diffusion-approximation-based models are valid for quantitative measurements and tomographic imaging of tissues in the visible.     

Implementation of a constant‐time dynamic storage allocator

This paper describes the design criteria and implementation details of a dynamic storage allocator for real‐time systems. The main requirements that have to be considered when designing a new allocator are concerned with temporal and spatial constraints. The proposed algorithm, called TLSF (two‐level segregated fit), has an asymptotic constant cost, O(1), maintaining a fast response time (less than 200 processor instructions on a x86 processor) and a low level of memory usage (low fragmentation). TLSF uses two levels of segregated lists to arrange free memory blocks and an incomplete search policy. This policy is implemented with word‐size bitmaps and logical processor instructions. Therefore, TLSF can be categorized as a good‐fit allocator. The incomplete search policy is shown also to be a good policy in terms of fragmentation. The fragmentation caused by TLSF is slightly smaller (better) than that caused by best fit (which is one of the best allocators regarding memory fragmentation). In order to evaluate the proposed allocator, three analyses are presented in this paper. The first one is based on worst‐case scenarios. The second one provides a detailed consideration of the execution cost of the internal operations of the allocator and its fragmentation. The third analysis is a comparison with other well‐known allocators from the temporal (number of cycles and processor instructions) and spatial (fragmentation) points of view. In order to compare them, a task model has been presented. Copyright © 2007 John Wiley & Sons, Ltd.     

The effect of enriching milk‐based beverages with plant sterols or stanols on the fatty acid composition of the products

Five plant sterol (PS)‐enriched dairy products from the Spanish market were characterised for fatty acids (FA), volatile compounds and lipid stability. The ingredients used for PS enrichment by the food industry may come from different sources, thus influencing the composition and stability of the lipid fraction. In this study, the FA profile proved highly variable among samples, not agreeing with the nutritional labelling of the products. The volatile profile was characterised. A total of 55 volatile compounds were identified in the samples by GC–MS. Concentrations of hexanal (from 1.1 to 7.5 ng/g), nonanal (from 0.9 to 1.2 ng/g) and decane (from n.d. to 11.9 ng/g) indicated a low lipid oxidation extent. Peroxide value, ranking between 0.7 and 3.2 meq of active oxygen per kilogram of fat, except sample with fish oil, where peroxide value was 7.7 meq of active oxygen per kilogram of fat, and thiobarbituric acid reactive species, from 2 to 21 μg malondialdehyde (MDA)/g of fat, were in the lower limits of the ranges found in the literature.     

Automated motion correction for in vivo optical projection tomography

In in vivo optical projection tomography (OPT), object motion will significantly reduce the quality and resolution of the reconstructed image. Based on the well-known Helgason-Ludwig consistency condition (HLCC), we propose a novel method for motion correction in OPT under parallel beam illumination. The method estimates object motion from projection data directly and does not require any other additional information, which results in a straightforward implementation. We decompose object movement into translation and rotation, and discuss how to correct for both translation and general motion simultaneously. Since finding the center of rotation accurately is critical in OPT, we also point out that the system's geometrical offset can be considered as object translation and therefore also calibrated through the translation estimation method. In order to verify the algorithm effectiveness, both simulated and in vivo OPT experiments are performed. Our results demonstrate that the proposed approach is capable of decreasing movement artifacts significantly thus providing high quality reconstructed images in the presence of object motion.     

Effect of slaughter weight and breed on instrumental and sensory meat quality of suckling kids

The effects of breed and slaughter weight on chemical composition, fatty acid groups, texture, and sensory characteristics of meat of 141 suckling male kids from 5 Spanish breeds were studied. There was a decrease in texture and lightness and hue angle with the increase of the slaughter weight. Fatty acid composition was correlated with the intramuscular fat content. All the breeds except MO had values of n-6/n-3 ratio below 4, which is the healthy limit recommended, and a low atherogenic index as well as a low intramuscular fat content. A multivariate analysis discriminated light kid, which had the most tender and juicy meat, from heavy kid which had more intense kid and milk odours. Blanca Andaluza and Pirenaica had most tender and juicy meat. The effect of slaughter weight on meat traits should be considered separately for each breed to find the most appropriate meat according to consumers preferences.     

Influence of alfalfa grazing-based feeding systems on carcass fat colour and meat quality of light lambs

One hundred and twenty-seven lambs were fed as follows: lambs and dams grazing alfalfa (Gr); the same as Gr but lambs had access to concentrate (Gr + S); ewes grazed and lambs received milk and concentrate until weaning and thereafter concentrate and straw (Rat-Gr); ewes and lambs were stall-fed (Ind). Lambs were slaughtered at 22-24 kg live weight and fat and M. rectus abdominis colour was measured instrumentally and subjectively. The evolution of the instrumental colour and texture of M. longissimus lumborum was also recorded.There were significant differences in the instrumental colour of subcutaneous fat amongst feeding systems, but no differences were observed upon visual appraisal. On average, M. rectus abdominis colour in the four feeding systems was classed as pink. Differences in longissimus thoracis colour at 0 h disappeared at 24 h of air exposure and there were no differences in pH or cooking losses. At no time were any differences in instrumental texture found.     

Predicting meat yields and commercial meat cuts from carcasses of young bulls of Spanish breeds by the SEUROP method and an image analysis system

The SEUROP system is currently in use for carcass classification in Europe. Image analysis and other new technologies are being developed to enhance and supplement this classification system. After slaughtering, 91 carcasses of local Spanish beef breeds were weighed and classified according to the SEUROP system. Two digital photographs (a side and a dorsal view) were taken of the left carcass sides, and a total of 33 morphometric measurements (lengths, perimeters, areas) were made. Commercial butchering of these carcasses took place 24 h postmortem, and the different cuts were grouped according to four commercial meat cut quality categories: extra, first, second, and third. Multiple regression analysis of carcass weight and the SEUROP conformation score (x variables) on meat yield and the four commercial cut quality category yields (y variables) was performed as a measure of the accuracy of the SEUROP system. Stepwise regression analysis of carcass weight and the 33 morphometric image analysis measurements (x variables) and meat yield and yields of the four commercial cut quality categories (y variables) was carried out. Higher accuracy was achieved using image analysis than using only the current SEUROP conformation score. The regression coefficient values were between R² = 0.66 and R² = 0.93 (P < 0.001) for the SEUROP system and between R² = 0.81 and R² = 0.94 (P < 0.001) for the image analysis method. These results suggest that the image analysis method should be helpful as a means of supplementing and enhancing the SEUROP system for grading beef carcasses.     

Use of dietary vitamin E and selenium (Se) to increase the shelf life of modified atmosphere packaged light lamb meat

The aim of this work was to determine the increase in the shelf life of modified atmosphere packaged fresh lamb meat due to the effect of dietary vitamin E and selenium supplementation on colour and lipid oxidation. 128 lambs were fed on a concentrate with standard levels of vitamin E (C), a concentrate enriched with vitamin E (V), a concentrate with sodium selenite (S) and a concentrate enriched with both vitamin E and sodium selenite (VS). The lambs were slaughtered at 27.3±1.45 kg LW, and chops stored on MAP for 7, 9, 11 and 13 days. CIELab colour and TBARs were studied on these days. Use of dietary vitamin E extended the shelf life a further 4 days from the commercial sell-by date in terms of lightness, hue angle, metmyoglobin formation and lipid oxidation. Selenium could be used to increase the lightness of meat without vitamin E supplementation in lambs' diets.