Current decomposition in asymmetrical, unbalanced three-phasesystems under nonsinusoidal conditions

The most attractive theories found in the literature for the representation of the electrical systems under nonsinusoidal conditions can be divided to a great extent into those operating in the time domain and those operating in the frequency domain. When three-phase systems are concerned, the time-domain approach is mainly due to Akagi and Nabae under the name of “instantaneous power theory” or “p-q theory” and is based on the Park transformation. The frequency-domain approach is mainly due to Czarnecki. At a first reading, these two theories seem to be quite different. This paper shows how the application of some interesting properties of the Park transformation leads to a unified approach to the harmonic and sequence components and hence allows derivation of the frequency-domain current decomposition proposed by Czarnecki in a more straightforward way. Moreover, an extension of this decomposition to the case of asymmetrical supply voltages is considered     

The thermoelastic behaviour of semicrystalline and of glassy poly(ether-ether-ketone)

A thermoelastic evaluation, based on simultaneous measurements of the mechanical work and of the concomitant heat of deformation by a stretching micro calorimeter, was performed on semicrystalline and glassy PEEK. The objective of this study was to utilize the sensitive technique to detect differences that would account for observed effects of micro structure on mechanical performance. A clear difference was detected beyond a 0.6% strain, where the behaviour of glassy PEEK began to exhibit inelastic features such as yielding and plastic deformation. This difference between the glassy and the semicrystalline polymers was considered the reason for the superior mechanical fatigue and fracture properties produced by the latter micro structure.     

The dominance of the K I-field for a crack under stress wave loading

The extent of the dominant singular field is investigated for a finite crack under stress wave loading. Using a boundary integral equation method the complete solution as well as the near field solution is determined. A comparison of the two fields indicates that the singular field dominates within a small domain at the crack tip. The size of the dominance region in the dynamic case may be very different from that in the static case.     

Fluorescence flow cytometry of human leukocytes in the detection of LDL receptor defects in the differential diagnosis of hypercholesterolemia

A flow-cytometric method with fluorescence-labeled monoclonal antibodies (MABs) against the low density lipoprotein (LDL) receptor (C7A MAB) or 3,3'-dioctadecylindocarbocyanin-iodide (DiI) LDL has been developed that allows the quantification of LDL receptors on leukocytes and the identification of patients with familial hypercholesterolemia (FH) within 48 hours. Leukocytes were isolated from 10 mL anticoagulated blood by density gradient centrifugation. To induce maximal expression of LDL receptors, mononuclear cells were preincubated with either phytohemagglutinine (PHA) or lipoprotein-deficient serum (LPDS). LPDS-treated monocytes provided a more homogeneous cell population with regard to LDL receptor activity than did the PHA-treated lymphocytes; they also provided a greater discrimination between the fluorescence of the receptor probes and cellular autofluorescence. The C7A MAB was able to compete for DiI LDL binding by about 40%. In competition with unlabeled LDL, DiI LDL revealed linear binding, indicating an affinity similar to native LDL. The binding characteristics of DiI LDL were also similar to 125I-LDL binding. LDL isolated from familial defective apolipoprotein B-100 was not able to compete for DiI LDL binding on monocytes, whereas native LDL reduced it by about 80%. In monocytes from FH heterozygous patients, the cellular mean fluorescence using either C7A MAB or DiI LDL at 4 degrees C was 30% to 70%; in FH homozygotes, cellular mean fluorescence was less than 20% of that in monocytes from normal individuals. In patients with familial defective apolipoprotein B-100 antibody binding was normal, but one patient's own LDL failed to compete with normal DiI LDL for 4 degrees C binding on U937 test monocytes. Patient monocytes having internalization defects showed normal 4 degrees C DiI LDL binding, but at 20 degrees C cell-associated fluorescence was reduced by about 40%. In our study 384 hypercholesterolemic patients (preselected according to serum cholesterol levels, clinical symptoms, and family history) were analyzed for LDL receptor expression using the C7A MAB-based assay. In 71.8% of the patients with cholesterol levels higher than 300 mg/dL, an LDL receptor deficiency was observed. Apolipoprotein E isoforms and lipoprotein[a] were found to be independent from the LDL receptor status. In some patients with high cholesterol levels but normal LDL receptor expression with the C7A MAB assay, LDL receptor defects could be diagnosed when either reduced binding or internalization of DiI LDL or familial defective apolipoprotein B-100 was detected.(ABSTRACT TRUNCATED AT 400 WORDS)