Design of low-leakage power supply transformers for high-precisionelectronic instruments

In most electronic instruments, the magnetic interference generated by the power supply transformer induces noise in the measuring circuitry, limiting the overall precision of the instrument and significantly reducing its accuracy at low-level measurements. A method for reducing the intensity of the noise-signal, which is based on a low-leakage design of the power supply transformer, is presented, and its effectiveness is demonstrated through testing of a prototype designed and built according to the design procedure given here. Finite-element analysis is used to predict the magnetostatic performance of the transformer design prior to building a prototype. It is demonstrated that the finite-element analysis is an effective tool for saving time and resources in developing transformer prototypes     

Parameter Estimation for Power Transformer Models from Time-Domain Data

The existence of power system harmonics has been realized for many years. With the advent of new technologies and more solid state loads, power system harmonics are certain to increase both in amplitude and frequency bandwidth. Signal propagation in power systems depends on transformer impedances. Transformer impedances, on the other hand, are functions of signal frequency as well as input voltage and loading condition. Present power transformer models with single-valued parameters obtained from tests cannot adequately represent the transformer in the presence of harmonics. Accurate modeling of transformers must account for changes in signal frequencies and loading conditions as they occur. This paper presents algorithms for estimation of the parameters of a structurally known transformer model. These algorithms use time-domain data and continuously update the estimates, thereby accounting for changes in operating conditions. The techniques presented here can be applied to three-phase and single-phase N-winding transformers. The results of model identification for a single-phase two-winding transformer is given. The data acquisition system used and the problem of identification in a noisy environment are discussed. The simulated response of the identified model is compared with the transformer actual response.     

Regulation of Survival Motor Neuron Gene Expression by Calcium Signaling

Spinal muscular atrophy (SMA) is caused by homozygous survival of motor neurons 1 (SMN1) gene deletion, leaving a duplicate gene, SMN2, as the sole source of SMN protein. However, a defect in SMN2 splicing, involving exon 7 skipping, results in a low level of functional SMN protein. Therefore, the upregulation of SMN protein expression from the SMN2 gene is generally considered to be one of the best therapeutic strategies to treat SMA. Most of the SMA drug discovery is based on synthetic compounds, and very few natural compounds have been explored thus far. Here, we performed an unbiased mechanism-independent and image-based screen of a library of microbial metabolites in SMA fibroblasts using an SMN-specific immunoassay. In doing so, we identified brefeldin A (BFA), a well-known inhibitor of ER-Golgi protein trafficking, as a strong inducer of SMN protein. The profound increase in SMN protein was attributed to, in part, the rescue of the SMN2 pre-mRNA splicing defect. Intriguingly, BFA increased the intracellular calcium concentration, and the BFA-induced exon 7 inclusion of SMN2 splicing, was abrogated by the depletion of intracellular calcium and by the pharmacological inhibition of calcium/calmodulin-dependent kinases (CaMKs). Moreover, BFA considerably reduced the expression of Tra2-β and SRSF9 proteins in SMA fibroblasts and enhanced the binding of PSF and hnRNP M to an exonic splicing enhancer (ESE) of exon 7. Together, our results demonstrate a significant role for calcium and its signaling on the regulation of SMN splicing, probably through modulating the expression/activity of splicing factors.     

Adolescents' Attachment Representations and Developmental Tasks in Emerging Adulthood.

The association between attachment representations and adolescents' coping with 3 developmental tasks of emerging adulthood-leaving home, advancing in the capacity for mature intimacy, and developing individuation-was examined. Israeli male adolescents (N = 88) were administered the Adult Attachment Interview during their high-school senior year. A year later, they and their friends reported on the adolescents' adjustment to mandatory military service. Three years later, participants and their parents reported on the adolescents' capacity for intimacy using an in-depth interview and on their individuation. An autonomous state of mind was associated with better coping with basic training and with a higher capacity for mature intimacy but was not associated with markers of individuation. The results highlight the importance of attachment representations in shaping an individual's developmental trajectory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

(31)P NMR study of post mortem changes in pig muscle

The rate and the extent of post mortem pH changes in pig muscle largely determine pork quality. Fast pH fall combined with low ultimate pH leads to pale soft exudative (PSE) meat; high ultimate pH leads to dark firm dry (DFD) meat. Post mortem metabolism was studied in pig muscle using(31)P NMR. Fifteen pigs, i.e. 7 Large White pigs and 8 Pietrain pigs, were used. Five pigs of each breed were slaughtered, taking care to minimize preslaughter stress. The other pigs (3 Large Whites and 2 Pietrains) were injected with 0·1 mg adrenaline per kg liveweight before slaughter, in order to increase meat ultimate pH. All the animals were killed by electronarcosis and exsanguination. Three of the adrenaline-treated pigs (1 Large White and 2 Pietrains) gave meat with ultimate pH above 6 (DFD meat). The pigs with normal muscle ultimate pH, i.e. 6 Large Whites and 6 Pietrains, had very variable rates of post mortem muscle metabolism (pH at 30 min after slaughter: 6·17-6·85 in Large Whites; 6·04-6·23 in Pietrains). The relationships between pH and ATP changes were similar in all pigs showing normal muscle ultimate pH, whereas ATP disappeared at a high pH value (on average pH 6·4) in pigs with high ultimate pH. The course of post mortem biochemical changes in a given animal could be predicted rather well by examination of a single(31)P NMR spectrum obtained around 30 min after death. At this time, muscle with a low rate of metabolism simultaneously showed medium to high pH, high ATP content (4-6·8 μmol/g) and rather low Pi content (6-14 μmol/g); muscle with a fast rate of metabolism (PSE-prone muscle) had low pH, low to medium ATP content (1·1-4 μmol/g) and generally high phosphomonoester (PME) content (9-23 μmol/g); muscle with high ultimate pH (DFD-prone muscle) had high pH, low PME content (4-8 μmol/g) and high Pi content (22-27 μmol/g).     

Application of MADM in a fuzzy environment for selecting the best barrier for offshore wells

A fuzzy Multi Attribute Decision Making (FMADM) method, which is suitable for treating group decision making problems in a fuzzy environment, is proposed for ranking offshore well barriers from a cost-benefit view point. It is obvious that much knowledge in the real world is fuzzy rather than precise. MADM decision data is usually fuzzy, crisp, or a combination of the two. A useful model is proposed here in order to handle both fuzzy and crisp data. Imprecision and ambiguity in the calculation of a performance rating are incorporated into MADM whereby fuzzy set theory provides a mathematical framework for modeling them. Human opinions often conflict in group decision-making. The purpose of fuzzy MADM is to aggregate the conflicting opinions. In general, one expert’s opinion for a given attribute may be different from others’. Therefore, it is necessary to develop an appropriate method of aggregating multiple experts’ opinions, taking into account a degree of importance of each expert in the aggregation procedure. The weights of all attributes and experts are estimated using a Fuzzy Analytical Hierarchy Process (FAHP). Finally, the best well barrier or risk control option (RCO) with respect to cost and benefit is selected using a Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method.     

New neural network-based response surface method for reliability analysis of structures

Neural Computing and Applications - In this paper, a new algorithm is introduced for reliability analysis of structures using response surface method based on a group method of data handling-type...