Seawater reverse osmosis—Statement of the art assessment

Considerable time and effort has been spent in developing new membranes and system configurations for Seawater Reverse Osmosis. This has led to reverse osmosis being accepted as a viable method for seawater desalination.     

Aging tests performed on full 108-kV current limiting arresters

This report presents results of aging tests on two modern new 108-kV arresters; the tests were carried out in order to investigate the variation of the main features of the arresters with life.These tests were performed with a new prototype circuit called a “resonant circuit”, which has been designed at the Hydro-Quebec Research Institute; the equivalent power of this circuit is 2160 MVA (i.e., 108 kV, 20 kA).The two arresters were submitted to 650 and 300 tests, respectively, of average severity. These approximate ten times the number of operations of an arrester during a normal life, and produced no sign of degradation.To our knowledge, such tests have never been performed before on full arresters at such a high voltage. They enabled us to detect particular phenomena and minor defects in one of the arresters.     

Infra-red analysis of poly(vinylidene fluoride) thermoelectrets

The copolymer poly(vinylidene fluoride)—poly(tetrafluoroethylene) studied by infra-red spectroscopy during its transformation into electrets, shows structural modifications of the copolymer due to the electrostatic field action. The dielectric used is a copolymer monoaxially oriented by stretching and the paper reports on the structural changes in the molecular arrangements, relative to the induced electrical properties. These results complete and confirm data obtained previously by Raman spectroscopy^1,7.     

Modeling assessment for re-use of traditional and new types of assessment

In the new learning approach assessment is integrated in learning and instruction and addresses complex traits (the abilities, the characteristics in a specific domain) of students. To match this new approach, new types of assessment are developed, like peer assessment or competence assessment. The development of these new assessments is an expensive and intensive activity. Exchange initiatives promise to reduce those efforts by the re-use of materials. But they also raise questions: is it a complete assessment or are there specific parts of an assessment that can be re-used? And is re-use limited to particular item formats? In order to support the re-use of both new and traditional assessment types an educational model for assessment is developed.In this article we present this model. The model is validated against [Stiggins, R. J. (1992). Het ontwerpen en ontwikkelen van performance-assessment toetsen [Design and development of performance assessments]. In J. W. M. Kessels, & C. A. Smit (Eds.). Opleiders in organisaties/Capita Selecta (pp. 75–91). Deventer: Kluwer (afl. 10)] guidelines for the development of performance assessments, the four-process framework of [Almond, R. G., Steinberg, L., & Mislevy, R. J. (2001). A sample assessment using the four-process framework. CSE Report 543. Center for study of evaluation, University of California, Los Angeles. Retrieved November 15, 2005 from http://www.cse.ucla.edu/cresst/reports/tech543.pdf; Almond, R. G., Steinberg, L., & Mislevy, R. J. (2003). A four-process architecture for assessment delivery, with connections to assessment design. CSE Report 616. Center for study of evaluation. University of California, Los Angeles], a specification for the exchange and interoperability of assessments and performance assessment as a new type of assessment. The educational model for assessment gives new input to the alignment of the teaching, learning and assessment.     

Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching

Biofilms are complex structures formed by a community of microbes adhering to a surface and/or to each other through the secretion of an adhesive and protective matrix. The establishment of these structures requires a coordination of action between microorganisms through powerful communication systems such as quorum-sensing. Therefore, auxiliary bacteria capable of interfering with these means of communication could be used to prevent biofilm formation and development. The phytopathogen Rhizobium rhizogenes, which causes hairy root disease and forms large biofilms in hydroponic crops, and the biocontrol agent Rhodococcus erythropolis R138 were used for this study. Changes in biofilm biovolume and structure, as well as interactions between rhizobia and rhodococci, were monitored by confocal laser scanning microscopy with appropriate fluorescent biosensors. We obtained direct visual evidence of an exchange of signals between rhizobia and the jamming of this communication by Rhodococcus within the biofilm. Signaling molecules were characterized as long chain (C₁₄) N-acyl-homoserine lactones. The role of the Qsd quorum-quenching pathway in biofilm alteration was confirmed with an R. erythropolis mutant unable to produce the QsdA lactonase, and by expression of the qsdA gene in a heterologous host, Escherichia coli. Finally, Rhizobium biofilm formation was similarly inhibited by a purified extract of QsdA enzyme.     

Effects of added lard fed to broiler chickens during the starter phase. 2. Serum lipids

The effects of lard added to starter diets on various serum lipids were determined in broiler chickens between 14 and 42 d of age. Nonisocaloric starter diets were formulated to contain either 0, 3, or 7% added lard, where the megacaloric percentages of all major nutrients were held constant. Birds received either 0, 3, or 7% added lard in starter diets through 10 d of age (S1), followed by either 3 or 7% added dietary lard through 21 d of age (S2). All possible combinations of the three S1 diets and two S2 diets yielded six total dietary treatments. A common grower diet was provided after 21 d. Concentrations of various serum lipids were determined weekly from 14 to 42 d of age. The effects of both the S1 and S2 diets on total cholesterol, low density lipoprotein cholesterol (LDLC), and high density lipoprotein cholesterol (HDLC) were inconsistent and were influenced by sex between 14 and 42 d of age. However, serum triglycerides and very low density lipoprotein cholesterol concentrations showed progressive increases over the 14 to 42 d period in birds that received dietary lard at either level in the S1 diet. These same serum constituents also increased to the greatest extents over the same period when birds were provided 3% added lard in the S2 diet. It was concluded that the response of broiler chickens between 14 and 42 d to different levels of dietary lard were influenced by age of feeding during the starter period. Furthermore, the specific effects of the diets on serum cholesterol, LDLC, and HDLC concentrations between 14 and 42 d varied with the sex and age of the bird.     

Identification in closed‐loop operation of models for collective pitch robust controller design

To achieve load reduction and power optimization, wind turbine controllers design requires the availability of reliable control‐oriented linear models. These are needed for model‐based controller design. Model identification of wind turbine while operating in closed loop is an appropriate solution that has recently shown its capabilities when linear time‐invariant controllers and complicated control structures are present. However, the collective pitch control loop, one of the most important wind turbine loops, uses non‐linear controllers. Typically, this non‐linear controller is a combination of a linear controller and a gain scheduling. This paper presents a new algorithm for identification in closed‐loop operation that allows the use of this kind of non‐linear controllers. The algorithm is applied for identification the collective pitch demand to generator speed of a wind turbine at various operating points. The obtained models are presented and discussed from a control point of view. The validity of these models is illustrated by their use for the design of a linear fix robust controller. The performance based on simulation data of this linear controller is similar to that obtained with simulations based on a linear controller with gain scheduling, but its design and implementation is much simpler. Copyright © 2012 John Wiley & Sons, Ltd.