Prediction of diesel fuel cold properties using artificial neural networks

In this paper, two neural networks, multilayer perceptron and networks with radial-basis function, were used to predict important cold properties of commercial diesel fuels, namely cloud point and cold filter plugging point. The developed models predict the named properties using cetane number, density, viscosity, contents of total aromatics, and distillation temperatures at 10, 50, and 90 vol. % recovery as input data. The training algorithms, number of hidden layer neurons, and number of training data points were optimized in order to obtain a model with optimal predictive ability. The results indicated better prediction of cloud and cold filter plugging points in the case of multilayer perceptron networks. The obtained absolute error mean for the optimal neural network models (0.58°C for the cloud point and 1.46°C for the cold filter plugging point) are within the range of repeatability of standard cold properties determination methods.     

Effect of fine particles on some characteristics of granular base courses

The paper presents the results of a scientific research program focused on determining the effect of the fine particles content in granular stone materials on particular properties of the unstabilized base course. Grain-size distribution of a granular system was within the defined limits, and the percentage of fine particles (<0.02 mm in diameter) ranged from 0 to 10% by mass. Two types of fine particles were tested, those of stone and clay origin. The specimens were compacted using five energy levels. Used lab. equipment was in compliance with the requirements of German (DIN) and Swiss (SNV) standards.

Changes in skeletal metabolism in pubertal girls can be revealed by biochemical parameters of calcium metabolism and bone turnover

Biochemical changes related to skeletal turnover in puberty were investigated in a sample of 67 girls aged 8-14 years. The following biochemical parameters were measured in serum: total calcium, phosphate, magnesium, total alkaline phosphatase, osteocalcin, and calcium and hydroxyproline in the second morning urine. Thirty-five premenarchal girls (8-11 years) had significantly lower serum calcium, and higher alkaline phosphatase and phosphate than those menstruating regularly (N = 32, 12-14 years). A statistically significant negative correlation of serum parameters and age was found for phosphate and alkaline phosphatase in all subjects, and for calcium and magnesium only in the premenarchal girls. These results indicated the more intensive processes of skeletal metabolism occurring in prepubertal age and early puberty to reflect in basic biochemical parameters of calcium and bone metabolism. Analysis of correlation between biochemical parameters showed alkaline phosphatase and phosphate to correlate positively with hydroxyproline excretion and negatively with urinary calcium in all subjects. In the subjects after menarche, osteocalcin correlated with alkaline phosphatase and phosphate. Thus, biochemical parameters indirectly reflected physiologic changes occurring with bone turnover in puberty. Variations in bone turnover during puberty, including a more pronounced bone formation during prepubertal or early stages, can be indirectly observed through biochemical parameters related to calcium and bone metabolism. Investigations of skeletal growth and puberty would benefit from specific markers of bone remodeling and "basic" biochemical parameters, as it might disclose subtle metabolic relationships.     

Heart mitochondrial dysfunction in diabetic rats

Diabetic cardiomyopathy, i.e. the ventricular dysfunction in the absence of hypertension or coronary arterial disease, is a common complication of diabetes mellitus that leads to a heightened risk of heart failure and death among diabetic patients. This contractile dysfunction could be associated to mitochondrial dysfunction, in which mitochondrial biogenesis could emerge as a compensatory mechanism triggered in response to hyperglycemia. It has been proposed that nitric oxide synthase activities with enhanced NO production are involved in this process. Alterations in the contractile response and lusitropic reserve were observed in streptozotocin diabetic rats after β-adrenergic stimuli. Additionally, tissue O₂ consumption was declined. A condition of mitochondrial dysfunction with decreased mitochondrial state 3 O₂ consumption, respiratory control ratio, mitochondrial respiratory complexes activities and ATP production were present in hearts of diabetic animals. We observed an increase in NO production by heart mitochondria and in cytochrome oxidase activity in heart homogenates. The latter suggests an increase of newly formed mitochondria. Thus, the impairment of mitochondrial function with increased mitochondrial biogenesis may precede the onset of diabetic cardiomyopathy. However, mitochondrial biogenesis does not necessarily imply that the resultant mitochondria are functional, which might explain the changes in cardiac energy metabolism occurring in hearts of diabetic rats.     

Mapping and monitoring contaminated-sediment geometry and stability

Environment Canada's National Water Research Institute (NWRI) conducts research on freshwater contaminated sediments, much of which is focused on designated areas of concern in the Great Lakes and their connecting channels. This paper reviews new acoustic and video equipment and procedures developed to map the geometry and stability of the sediments, and describes their applications. A RoxAnn acoustic seabed-classification system is used for mapping bottom-sediment types and locating the deposits of fine-grained sediments with which contaminants are associated. The system uses the acoustic properties of sediments to distinguish textural types ranging from mud to boulders, and displays the data as they are collected. The sediment thickness is measured with a weighted video-acoustic tripod which is lowered into the sediments to refusal, and which recorded penetration with a video camera or an echosounder transducer. The stability of the contaminated sediments was monitored with a bottom-mounted, high-precision echo sounder-digitizer, which logs changes in the position of the sediment-water interface produced by erosion or deposition. The same procedure can be used in capping or dredging projects to track bottom changes as they occur, or they can be measured by pre- and post-project mapping of bathymetry and morphology with sweep-sonar or side-scan sonar equipment. The new equipment and procedures have been successfully applied to a number of areas of concern in the Great Lakes basin. They provide a faster and more detailed characterization of sediment properties and geometry than was previously available, and have been particularly effective in optimizing sampling surveys and monitoring remediation projects.     

Elastic properties of cement-stabilised mixes with steel slag

In this study, we evaluated the elastic and mechanical properties of a new type of cement-stabilised material made with steel slag, varying the content of cement and steel slag. To study the elastic properties of these mixes, we measured their density, compressive strength and ultrasound pulse velocity at curing ages of 7, 28 and 90 days. The aggregate type and curing age greatly affected the elastic properties and varied much depending on the cement content. The Poisson's ratio chosen in analyses had little influence on the dynamic modulus. Various expressions given by building codes were used to predict the elastic properties of the mixtures. These codes generated very different values of the static modulus of elasticity, making most of them unsuitable for predicting the elastic properties of cement-stabilised materials. Using our experimental data, we provide the best combination of existing equations to predict elastic properties, and we conclude that measuring the ultrasound pulse velocity is a suitable way to predict the mechanic and elastic properties of cement-stabilised materials.     

Integration and its effect on acquiring knowledge about competing scientific theories for text.

Successful learning from scientific text depends upon a learner's ability to integrate successively encountered ideas in the text. High school and university students read texts that presented competing theories for ongoing scientific problems (e.g., the gradualist vs. catastrophic theories of dinosaur extinction) under two conditions: an integrated-text format versus a separate-text format. The integrated-text format was designed to portray science as inquiry and offered each theory as a possible solution to the scientific problem. The separate text presented the two theories successively in separate texts and made no mention of their conflicting nature. In general, the integrated-text format tended to facilitate performance on tests that measured integration of ideas rather than memory for discrete facts. The study showed that successful learning is also affected by learner characteristics, such as the maturity of the learner's epistemic views about knowledge and the capacity of the learner's working memory. The results suggest that integration processes contribute significantly to students' abilities to gain a deep understanding of science from written texts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of tensile strength of glass fiber straps

Glass fibers straps have been used for strengthening of masonry and concrete structures in the last decade. Recently, their use has become greater. This paper describes the research of measuring tensile strength of dry glass fiber straps as well as straps that were made of glass fibers and epoxy coating. The effect of strap widths, the effect of loading speeds and the effect of epoxy coating placed on fiber straps, on tensile strength of straps have been analyzed. Differences of tension strengths of fiber straps with and without epoxy coating are shown.