Development,characterisation and 1000 Suns outdoor tests of GaAs monolithic interconnected module (MIM) receivers

Monolithic interconnected modules (MIMs) are large area, high voltage PV devices which perform well at very high light intensities. They are therefore well suited for the assembly of dense array receivers. The latter can be employed in solar concentrator systems such as parabolic dishes at a concentration ratio of 1000 Suns or more. This paper reports on progress in the development and testing of GaAs MIMs and of water‐cooled dense array receivers assembled from MIMs. The MIMs are electrically protected by integrated bypass diodes and, under indoor laboratory tests, reach an efficiency of 20·0% at 1000 Suns and 22·9% at 200 Suns. Several dense array receivers have been assembled, one of which was tested outdoors at 1‐Sun and at concentration ratios of several hundred Suns and up to slightly above 1000 Suns using the PETAL solar dish facility in Sede Boqer, Israel. In addition to I–V curve measurements, the high‐concentration tests included measurements that quantified the light intensity distribution over the dense array. Deformations in some of the I–V plots were observed for intensity distributions that departed substantially from perfect uniformity. The shapes of these plots were successfully reproduced by an electronic network simulation of the inhomogeneously illuminated receiver. 1‐Sun I–V curve measurements and visual inspections performed before and after exposure of the module to concentrated sunlight revealed no indications of degradation. Copyright © 2007 John Wiley & Sons, Ltd.     

Transfer function conditions for (C',A,B) pairs

State-space conditions for the solution of the output feedback disturbance rejection problem have been given in a recent paper [1] in terms of (C', A, B) pairs. This paper develops constructive and simple solvability conditions for this problem in terms of the rational matrix equationG(s)X(s)N(s)= - H(s).     

The effect of antibiotic prophylaxis on patients undergoing total abdominal hysterectomy. II. Alterations of microbial flora

Preoperative cultures of the endocervix were taken on 93 women who subsequently underwent total abdominal hysterectomy and received a 5 day course of either prophylactic cephalosporins or placebo. Postoperative cultures of the vaginal apex were taken on 86 of these women 5 days after surgery, i.e. 1 day after the cessation of study medication. Comparisons of the preoperative and postoperative flora in both the active drug and placebo groups as well as comparisons between the postoperative flora of the drug group and that of the placebo group were made. Postoperative alterations of bacterial flora occurred whether or not the patient received prophylactic antibiotics.     

A study on the dewatering of industrial waste sludge by fry-drying technology

In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge. Many methods have been applied, including direct and indirect heat drying, but these approaches of reducing water content to below 40% after drying is very inefficient in energy utilization of drying sludge. In this study, fry-drying technology with a high heat transfer coefficient of approximately 500 W/m² °C was used to dry industrial wastewater sludge. Also waste oil was used in the fry-drying process, and because the oil's boiling point is between 240 and 340 °C and the specific heat is approximately 60% of that of water. In the fry-drying system, the sludge is input by molding it into a designated form after heating the waste oil at temperatures between 120 and 170 °C. At these temperatures, the heated oil rapidly evaporates the water contained in the sludge, leaving the oil itself. After approximately 10 min, the water content of the sludge was less than 10%, and its heating value surpassed 5300 kcal/kg. Indeed, this makes the organic sludge appropriate for use as a solid fuel. The wastewater sludge used in this study was the designated waste discharged from chemical, leather and plating plants. These samples varied in characteristics, especially with regard to heavy metal concentration. After drying the three kinds of wastewater sludge at oil temperatures 160 °C for 10 min, it was found that the water content in the sludge from the chemical, leather, and plating plants reduced from 80.0 to 5.5%, 81.6 to 1.0%, and 65.4 to 0.8%, respectively. Furthermore, the heat values of the sludge from the chemical, leather, and plating plants prior to fry-drying were 217, 264, and 428 kcal/kg, respectively. After drying, these values of sludge increased to 5317, 5983 and 6031 kcal/kg, respectively. The heavy metals detected in the sludge after drying were aluminum, lead, zinc, mercury, and cadmium. Most importantly, if the dried sludge is used as a solid fuel, these heavy metals can be collected from the dust collector after combustion.     

Microactuators: Control of the Properties of Micrometer Sized Actuators from Liquid Crystalline Elastomers Prepared in a Microfluidic Setup (Adv. Funct. Mater. 24/2010)

In this article new results on the preparation of monodisperse particles from a liquid crystalline elastomer in a microfluidic setup are presnted. For this, droplets from a liquid crystalline monomer are prepared in a microfluidic device and polymerized while they are flowing inside a microtube. The parti­cles obtained by this method possess an internal orientation, which gives them actuating properties. When they are heated into the isotropic phase of the liquid crystalline material they show a reversible change in shape whereby they change their length in one direction by almost 100%. It is shown how the variation of experimental parameters during their synthesis impacts the properties of these micro‐actuators. Influence over their primal shape, the strength of their shape changing properties, their size, and their mechanical properties is demontrated. From the systematic variation of experimental parameters a deep understanding of the complex processes taking place in a flowing droplet of a liquid crystalline material is obtainted. Additionally NMR analysis and swelling experiments on these actuating materials are provided.     

Factors influencing users’ employment of mobile map services

This study introduces an integrated research model to examine user acceptance of mobile map services, hypothesizing potential causal connections between key cognitive factors and users’ intention to use the services. This study determined potential variables that may be significantly related to perceived usefulness of mobile map services through in-depth interviews with two groups: a user and an expert group. Collected data of 1109 users who took part in the internet survey were analyzed using structural equation modeling. The results indicate that satisfaction with and perceived usefulness of the mobile map services were the most significant antecedents of users’ attitude toward the services and behavioral intention to use them. Users’ attitude and flow state also affected their intention to use the services, while perceived locational accuracy, service, and display quality had notable effects on attitude. This study demonstrates the significant effects of these and other examined factors, and the findings reveal that flow played a multiple moderating roles significantly affecting various connections in the integrated research model. Both theoretical and practical implications are discussed.