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101.
Yael Augarten Thorsten Trupke Martha Lenio Jan Bauer Juergen W. Weber Matthias Juhl Martin Kasemann Otwin Breitenstein 《Progress in Photovoltaics: Research and Applications》2013,21(5):933-941
A proof of concept study for a method of determining quantitative shunt values in silicon solar cells from photoluminescence images is presented. The method is based on interpretation of the luminescence intensity around a local shunt or recombination‐active defect in terms of the extracted current. The theoretical relationship between the photoluminescence signal and the shunt current is derived. Experimental results on specifically prepared test structures show good agreement with known shunt resistance values. Experimental data on diffused wafers are presented. The effect of the front metallisation in complete cells on the appearance and interpretation of shunts in photoluminescence images is investigated experimentally. The limitations of the method are discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
102.
Joseph A. Levi Yosef A. Solewicz Yael Dvir Yisca Steinberg 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2011,15(3):461-468
In the use of optical answer sheet examinations, occasionally the identity of the examinee is in question. A novel method
for characterizing the personal quality of mark shapes in optically read answer sheets is described. The method may be used
to identify imposters in multiple choice examinations. All the marks are segmented and measured in multiple parameters including
area, dimensions, perimeter and optical density. Imposter decisions are made on the collected data by comparing an identified
test form against the form in question in comparison with a population using SVM (support vector machine) modeling. In testing
the method, 300 test forms from 100 examinees from past tests were used. An EER (equal error rate) of 15–17% was found. While
performance of the presented method is currently insufficient for practical purposes, future research options have been mentioned. 相似文献
103.
This study investigated the use of modified atmosphere packaging (MAP) to extend the shelf life of soy bread with and without calcium propionate as a chemical preservative. The bread samples were packaged in pouches made from low-density polyethylene (LDPE) as the control (film 1), high-barrier laminated linear low-density polyethylene (LLDPE)-nylon-ethylene vinyl alcohol-nylon-LLDPE (film 2), and medium-barrier laminated LLDPE-nylon-LLDPE (film 3). The headspace gases used were atmosphere (air) as control, 50% CO2-50% N2, or 20% CO2-80% N2. The shelf life was determined by monitoring mold and yeast (M+Y) and aerobic plate counts (APC) in soy bread samples stored at 21 degrees C +/- 3 degrees C and 38% +/- 2% relative humidity. At 0, 2, 4, 6, 8, 10, and 12 days of storage, soy bread samples were removed, and the M+Y and APC were determined. The preservative, the films, and the headspace gases had significant effects on both the M+Y counts and the APC of soy bread samples. The combination of film 2 in the 50% CO2-50% N2 or 20% CO2-80% N2 headspace gases without calcium propionate as the preservative inhibited the M+Y growth by 6 days and the APC by 4 days. It was thus concluded that MAP using film 2 with either the 50% CO2-50% N2 or 20% CO2-80% N2 was the best combination for shelf-life extension of the soy bread without the need for a chemical preservative. These MAP treatments extended the shelf life by at least 200%. 相似文献
104.
Holographic optical trapping 总被引:3,自引:0,他引:3
Holographic optical tweezers use computer-generated holograms to create arbitrary three-dimensional configurations of single-beam optical traps that are useful for capturing, moving, and transforming mesoscopic objects. Through a combination of beam-splitting, mode-forming, and adaptive wavefront correction, holographic traps can exert precisely specified and characterized forces and torques on objects ranging in size from a few nanometers to hundreds of micrometers. Offering nanometer-scale spatial resolution and real-time reconfigurability, holographic optical traps provide unsurpassed access to the microscopic world and have found applications in fundamental research, manufacturing, and materials processing. 相似文献
105.
Pita bread has a shelf-life of only a few hours, mainly due to its large surface to volume ratio. Hardening, caused by staling and drying, is the main factor affecting shelf-life. Extension of shelf-life by packaging pita in a high barrier laminate under modified atmosphere (MAP) of 99% CO2 or 73% CO2 with 27% N2 was studied. A shelf-life of 14 days, as determined by microbial spoilage, was obtained for MAP pita bread. Staling, as determined by means of a penetrometer, was delayed in MAP pita. Organoleptic hedonic comparisons of MAP pita, against frozen defrosted pita from the same batch, gave almost identical results. Shelf-life was terminated by the appearance of microorganisms on bread. 相似文献
106.
O?2 radicals were formed in the presence of 2,5- dimethyl benzoquinone (DMBQ). The equilibrium constant of the electron transfer reaction DMBQ + O?2 ? DMBQ? + O2 was determined. From this value and from E0(DMBQ/DMBQ?) we calculated the redox potential of the couple O2/O?2, as E0 (O2/O?2) = ?0.33 V. 相似文献
107.
108.
Undabeytia T Mishael YG Nir S Papahadjopoulos-Sternberg B Rubin B Morillo E Maqueda C 《Environmental science & technology》2003,37(19):4475-4480
A new approach was developed for reducing leaching of herbicides and contamination of groundwater. Liposome-clay formulations of the anionic herbicides sulfometuron and sulfosulfuron were designed for slow release by incorporating the herbicide in positively charged vesicles of didodecyldimethylammonium (DDAB), which were adsorbed on the negatively charged clay, montmorillonite. Freeze fracture electron microscopy demonstrated the existence of DDAB vesicles and aggregated structures on external clay surfaces. X-ray diffraction results for DDAB with montmorillonite imply the existence of DDAB bilayers with an oblique orientation to the basal plane within the clay interlayer space at adsorbed amounts beyond the cation exchange capacity of the clay. Adding DDAB with sulfometuron or sulfosulfuron to montmorillonite yielded 95% or 83% adsorption of the herbicide at optimal ratios. Liposome-clay formulations exhibited slow release of the herbicides in water. Analytical measurements in soil columns demonstrated 2-10-fold reduction in leaching of the herbicides from liposome-clay formulations in comparison with commercial formulations. Percents of root growth inhibition of a test plant in the upper soil depths were severalfold higher for the liposome-clay formulations than for the commercial ones. Consequently, liposome-clay formulations of anionic herbicides can solve environmental and economical problems by reducing their leaching. 相似文献
109.
Yael Motola Leslie Banks-Sills Victor Fourman 《International Journal of Fracture》2009,159(2):167-190
Fracture tests carried out on unpoled and poled PZT-5H four-point bend specimens are presented in this paper. The crack faces
were parallel to the poling direction. Both mechanical loads and electric fields were applied to the poled specimens. The
experimental results were analyzed by means of the finite element method and a conservative M-integral including the crack face boundary conditions. Fracture tests on four-point bend PIC-151 specimens with the crack
faces perpendicular to the poling directions were also analyzed here; the experimental results were taken from the literature.
A mixed mode fracture criterion is proposed for piezoelectric ceramics. This criterion is based upon the energy release rate
and two phase angles. This criterion was implemented with experimental results from the literature and from this investigation.
Excellent agrement was found between the fracture curve and the experimental results of the specimens with the crack faces
perpendicular to the poling direction. With some scatter, reasonable agreement was observed between the fracture curve and
the experimental results of the specimens with crack faces parallel to the poling direction. 相似文献
110.
The influence of supporting electrolytes on the equilibrium Cr2O72? + H2O ? 2 HCrO4? has been investigated with a view to comparing this influence with that exerted on the rates of reactions of similar charge-types. Neither the influence on the equilibrium constant nor that on the rate constant of the back reaction was found to be uniquely determined by the principle of ionic strength. These results, together with examples from the literature, show that there seems to be nothing special about environmental influence on the kinetics of reactions. It is suggested that what makes prediction difficult is the fact that in both cases activity coefficients appear in a combination which is different from that encountered in the mean activity coefficient. A spectrophotometric method is employed. The value of the equilibrium constant at zero ionic strength has been found equal to 4.4 × 10?2; the heat of reaction is 3.8 Kcal mol?1. The discrepancies between these values and those reported in the literature are discussed. 相似文献