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11.
The homopolyester of 4-(4′-hydroxyphenoxy)benzoic acid (poly(4-HPBA)), was prepared under two different reaction conditions and compared with a sample provided by another research group. Depending on the synthetic route, different melting points, d.s.c. traces and crystal lattices were found. However, after repeated heating and cooling, one thermodynamically stable modification with a melting point of 370–375°C can be obtained. Copolyesters of 4-hydroxybenzoic acid and 4-(4′-hydroxyphenoxy)benzoic acid were prepared with various molar ratios either in the melt (condensation in bulk) or in solution. These copolyesters were characterized by elemental analyses, 1H n.m.r. spectroscopy, d.s.c. measurements, wide-angle X-ray scattering measurements at various temperatures, and optical microscopy. Whereas copolyesters prepared in solution do not melt below 500°C, those prepared by polycondensation in bulk show melting points down to approximately 260°C and form a nematic melt. 相似文献
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Reliability aspects of microsensors and micromechatronic actuators for automotive applications 总被引:1,自引:0,他引:1
In modern cars microsensors and micromechatronic actuators play an essential and still increasingly important role as the interface between the vehicle with its complex functions of motor management, chassis systems, safety as well as comfort and convenience on the one hand and the respective electronic control units on the other hand. They have to fulfill their task in a harsh environment over the entire lifetime of an automobile. Therefore reliability aspects have moved more and more into the focus of engineering and research activities in microsystem technology. A methodical procedure is described that allows reliability issues to be approached efficiently. The implementation of the methodology is illustrated with real-life examples of reliability aspects of hot film mass air flow sensors, inertial sensors as well as piezoelectric actuators. 相似文献
14.
Hahlweg Kurt; Markman Howard J.; Thurmaier Franz; Engl Jochen; Eckert Volker 《Canadian Metallurgical Quarterly》1998,12(4):543
This article reports on the development and long-term evaluation of a marital distress prevention program for German couples, the Ein Partnerschaftliches Lernprogramm (EPL, A Couple's Learning Program). The EPL is a 6-session program designed to teach couples effective communication and problem-solving skills. In the current article, the EPL is evaluated in a prospective, quasi-experimental, controlled trial. The results of the 3-year follow-up are reported, contrasting 55 EPL couples with a control group of 17 couples. Significant differences emerged with regard to the couples' dissolution rates, relationship satisfaction, and positive and negative communication behavior favoring the EPL couples. These results demonstrate the utility of the EPL program in assisting happy couples who are preparing for marriage. The implications of the findings for prevention research and for the dissemination of prevention programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Volker Turau 《Information Processing Letters》2007,103(3):88-93
This paper presents distributed self-stabilizing algorithms for the maximal independent and the minimal dominating set problems. Using an unfair distributed scheduler the algorithms stabilizes in at most max{3n−5,2n} resp. 9n moves. All previously known algorithms required O(n2) moves. 相似文献
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This paper focuses on the harmonization of feed-in laws in the European Union as a support mechanism for the promotion of renewable electricity. In particular, it proposes a methodology for harmonization based on a feed-in law with a modular and transparent premium for renewable electricity producers. This premium considers technology costs, some grid services, political incentives and national priorities. The proposed approach includes flexibility mechanisms to update and revise premiums, to avoid windfall profits for producers, and to share technology innovation benefits with electricity consumers while maintaining incentives for innovation. Our approach is based on the review of the main features of the German and Spanish feed-in laws, and takes into account other necessary considerations for harmonization, such as grid access, funding, definitions and standards, ownership of rights derived from renewables, and exceptions for small non-commercial producers and energy-intensive industries. 相似文献
17.
Elvira S. Sandin Julica Folberth Helge Müller-Fielitz Claus U. Pietrzik Elisabeth Herold Thomas E. Willnow Paul T. Pfluger Ruben Nogueiras Vincent Prevot Thomas Krey Markus Schwaninger 《International journal of molecular sciences》2021,22(9)
The mechanisms underlying the transport of leptin into the brain are still largely unclear. While the leptin receptor has been implicated in the transport process, recent evidence has suggested an additional role of LRP2 (megalin). To evaluate the function of LRP2 for leptin transport across the blood-brain barrier (BBB), we developed a novel leptin-luciferase fusion protein (pLG), which stimulated leptin signaling and was transported in an in vitro BBB model based on porcine endothelial cells. The LRP inhibitor RAP did not affect leptin transport, arguing against a role of LRP2. In line with this, the selective deletion of LRP2 in brain endothelial cells and epithelial cells of the choroid plexus did not influence bodyweight, body composition, food intake, or energy expenditure of mice. These findings suggest that LRP2 at the BBB is not involved in the transport of leptin into the brain, nor in the development of obesity as has previously been described. 相似文献
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Adriana Tedesco Patrícia F Krey Ronilson V Barbosa Raquel S Mauler 《Polymer International》2002,51(2):105-110
Polyamide and polypropylene (PP) are two important classes of commercial polymers; however, their direct mixing leads to incompatible blends with poor properties. Polypropylene functionalized with glycidyl methacrylate (PP‐GMA) was used as a compatibilizer in blends of PP and nylon 6, because of the possible reaction of ? NH2 and ? COOH groups with the epoxide group of GMA. Two types of nylon 6 with different ratios between ? NH2 and ? COOH groups were used. The one with higher concentration of ? COOH groups was less compatible with PP in a binary blend. When PP‐GMA was used as a compatibilizer, a better dispersion of nylon in the PP matrix was obtained together with better mechanical properties for both nylons used in this work. © 2001 Society of Chemical Industry 相似文献
20.
Sabri A. Mahmoud Irfan Ahmad Wasfi G. Al-Khatib Mohammad Alshayeb Mohammad Tanvir Parvez Volker Märgner Gernot A. Fink 《Pattern recognition》2014
A comprehensive Arabic handwritten text database is an essential resource for Arabic handwritten text recognition research. This is especially true due to the lack of such database for Arabic handwritten text. In this paper, we report our comprehensive Arabic offline Handwritten Text database (KHATT) consisting of 1000 handwritten forms written by 1000 distinct writers from different countries. The forms were scanned at 200, 300, and 600 dpi resolutions. The database contains 2000 randomly selected paragraphs from 46 sources, 2000 minimal text paragraph covering all the shapes of Arabic characters, and optionally written paragraphs on open subjects. The 2000 random text paragraphs consist of 9327 lines. The database forms were randomly divided into 70%, 15%, and 15% sets for training, testing, and verification, respectively. This enables researchers to use the database and compare their results. A formal verification procedure is implemented to align the handwritten text with its ground truth at the form, paragraph and line levels. The verified ground truth database contains meta-data describing the written text at the page, paragraph, and line levels in text and XML formats. Tools to extract paragraphs from pages and segment paragraphs into lines are developed. In addition we are presenting our experimental results on the database using two classifiers, viz. Hidden Markov Models (HMM) and our novel syntactic classifier. 相似文献