An approach to the measurement of shunt resistance of individual subcells in thin‐film tandem devices

In this paper, the selective illumination approach is adopted to separately extract the shunt resistance of the individual subcells belonging to a tandem cell. The method relies on simple theoretical considerations and is based on the measurement of the current–voltage characteristic of the tandem cell by alternately keeping one of the subcells under dark conditions. Numerical simulations are employed to support the reliability of the technique, which is experimentally tested on micromorph devices deposited onto glass covered by a V‐shaped transparent conducting oxide and subject to different thermal treatments. Copyright © 2013 John Wiley & Sons, Ltd.     

An improved test structure for recombination lifetime profilemeasurements in very thick silicon wafers

A new test structure for recombination lifetime profile measurements has been designed and applied, for the first time, to the characterization of very thick bulk silicon wafers. The capability of the new test device to reject parasitic effects, affecting the reliability of the measure in bulk wafers, is shown by means of two-dimensional (2-D) simulations and experimental results. The proposed device has permitted the characterization of two P-type silicon bulk samples. For the first time a clear experimental evidence that the dopant acts as a recombination center has been found in this kind of material     

Cross sectional echocardiographic assessment of the extent of the atrial septum relative to the atrioventricular junction in atrioventricular septal defect

A study of brain lipids in patients with the sphingomyelinase-deficient types of Niemann-Pick disease demonstrated that abnormal accumulation of sphingomyelin occurs only in the brain of neuronopathic type A patients but not in the non-neuronopathic type B. Additional lipid abnormalities were present in the type A brain. In contrast, the brain lipid profile was normal in type B patients. Since lysosphingolipids have been implicated in the biochemical pathogenesis of other genetic lysosomal sphingolipidoses, the occurrence of sphingosylphosphorylcholine (lysosphingomyelin) was specifically investigated in brain and extraneural tissues, using an HPLC method with fluorescent detection of orthophtalaldehyde derivatives. Levels close to or below the limit of detection (10 pmol/mg tissue protein) were observed in normal and pathological controls. A striking accumulation was observed in brain of two Niemann-Pick type A patients (830 and 430 pmol/mg protein in 27-and 16-month-old children with severe and milder neurological course, respectively), which was not present at the fetal stage of the disease. No significant increase was found in brain tissue from a 3.5 year-old type B patient. In liver and spleen, abnormally high sphingosylphosphorylcholine levels were observed in both types of the disease, with indication of a progressive increase during development. This study establishes the integrity of brain tissue in Niemann-Pick disease type B and suggests that the lysocompound sphingosylphosphorylcholine could play a role in the pathophysiology of brain dysfunction in the neuronopathic type A.     

Anomalous origin of the left coronary artery from the anterior aortic sinus: role of echocardiography

Vancomycin-resistant enterococci recently isolated from patient specimens were tested with both Streptex and PathoDx group D latex agglutination antisera. Using routine protocols, all isolates from patients at Temple University Hospital were positive with the PathoDx reagents and were negative with the Streptex reagents. Isolates required extensive boiling for positive reactions to occur using Streptex reagents.     

A Possible Means to Assist the Processing of PET,PTT and PBT

Blends of PET, PTT and PBT with the corresponding MCOs have lower melt viscosities than the pure polymers. This effect of MCOs on viscosity has the potential for exploitation in polymer fabrication and especially in the processing of composite materials. Thus, the blends can be more easily melt‐processed than the pure polymers, and the MCOs can then subsequently be converted in situ into high‐molar‐mass polymers by ED‐ROPs. No catalyst is needed for the ED‐ROPs. It was shown that suitable polymer/MCO blends can be obtained directly by carrying out cyclo‐depolymerizations at appropriate concentrations. Suitable polymer/MCO blends can also, almost certainly, be obtained by carrying out the original polyester syntheses at lower concentrations than normally used.

     

A new outer‐rotor flux switching permanent magnet generator for wind farm applications

In this paper a 1.5 kW flux switching permanent magnet (FSPM) generator is presented for direct drive small scale wind turbine applications. For maximizing induced voltage and the output torque while minimizing cogging torque and unbalanced radial magnetic force (UMF), the proposed machine exhibits a new 6/19 stator pole/rotor teeth number and an outer rotor configuration. At first, in the paper an analytical design has been developed, then a finite element method (FEM) analysis is carried out for validating the analytical procedure and for design improvement. The simulation results extracted by FEM confirm the theoretical analysis procedure and help in the understanding of the performance analysis of the machine against the variations of the design variables. Furthermore, an experimental laboratory prototype of the proposed FSPM is implemented to confirm the analytical design and FEM modelling approaches. A comparison of induced voltage, torque, UMF and cogging torque produced by different FSPM configurations present in literature respect to the proposed generator has been developed. The results show the goodness of the adopted methodology and prove that, because of suitable electromagnetic performance of the proposed FSPM generator, it could be counted as a proper candidate for small scale wind turbine applications. Copyright © 2016 John Wiley & Sons, Ltd.     

A straightforward method to extract the shunt resistance of photovoltaic cells from current-voltage characteristics of mounted arrays

A straightforward non-invasive method is proposed to accurately evaluate the shunt resistance of an elementary cell of a photovoltaic module connected in an installed string without requiring prior knowledge of the parameters of the intrinsic diodes. The approach relies on the measurement of the current-voltage characteristic of the whole string after intentionally shading the selected cell. Calibrated PSPICE simulations are employed to illustrate the method and test its reliability. As a case study, the shunt resistances of several cells belonging to a series array of 10 commercial panels are determined.     

Two-dimensional analysis of a test structure for lifetime profilemeasurements

A new electrical measurement technique has been proposed that allows one to obtain the “local” lifetime value in Si layers, by superposing ac measurements on a dc bias in a three-terminal test structure, and hence to extract a lifetime “profile” along the depth of the layer by varying the voltage bias. In this paper two-dimensional effects that could arise due to the lateral current flow in the test structure are studied, and are related to the modifications of the lifetime profile extracted. Both a simplified analysis and 2-D simulations of the test structure behavior allow one to explain the 2-D effects responsible for deviation of the lifetime profile from the correct one as dependent on the geometry of the test structure. Moreover design rules are given for the test structure, that keep the error in the profile extracted within safe limits     

Experimental measurements of majority and minority carrier lifetime profile in SI epilayers by the use of an improved OCVD method

In this letter, the first experimental results of a recently proposed technique for measuring the carrier lifetime profile are presented. The technique makes use of a four-terminal bipolar test structure to electrically define the epilayer volume where recombination occurs and employs the open circuit voltage decay method for lifetime parameters extraction. For the capability of the test structure to depurate measurements from the parasitic ohmic effects, the technique is able to measure the ambipolar and minority carrier lifetime along epilayer at high and low injection levels respectively. Comparisons of measurements with numerical simulations are reported to confirm the validity of the proposed technique.