Long-Term Compression Performance of a Pultruded GFRP Element Exposed to Concrete Pore Water Solution

A durability study was performed on a pultruded glass fiber reinforced polymer (GFRP) compression element of a hybrid GFRP/steel joint for concrete structures. GFRP elements were immersed in alkaline pore water solutions of different temperatures during 18?months. Moisture uptake occurred very quickly, within a few days, mainly through a wicking effect along the fiber/matrix interfaces and matrix cracks. The loss of matrix stiffness due to swelling led to a first rapid and significant drop in element compression strength, because of the loss of matrix resistance against buckling of the compressed fibers. In the second phase, strength reduction due to chemical glass and matrix degradation occurred at a much slower rate. It was found that the Arrhenius rate law could predict the element strength decrease. Due to the less harsh environment in practice, the strength and stiffness decrease was found to be acceptable, thereby making it possible to assure structural safety and serviceability of the hybrid GFRP/steel joint after 70?years of service.     

Active millimetre-wave aperture-coupled microstrip patch antennaarray

An active millimetre-wave aperture-coupled microstrip patch and four element array are presented. The design methodology is discussed and experimental measurements between 41 and 42 GHz are presented. The results presented should have useful applications in phased arrays and communication systems at EHF frequencies     

Pharmacokinetics of stavudine (2',3'-didehydro-3'-deoxythymidine) in the neonatal macaque (Macaca nemestrina)

Our objective was to determine whether age effects the pharmacokinetics of stavudine (2',3'-didehydro-3'-deoxythymidine) in the neonatal pig-tailed macaque (Macaca nemestrina). The drug (5 mg/kg of body weight) was administered serially as a single intravenous bolus to the same four macaques at the ages of < 1 week, 1 month, and 4 months. Plasma clearance at < 1 week of age was significantly lower (P < 0.05) than the corresponding values at 1 month and 4 months. Our data indicate that the pharmacokinetics of stavudine change significantly with age in M. nemestrina.     

Hybrid transmission of analogue PAL and digital 64-QAM CATVchannels

A system experiment for fibre optic hybrid transmission of analogue CATV BK 300 and 1.8 Gbit/s with 64-QAM channels has been realised. It has been shown that additional transmission of 1.8 Gbit/s of compressed digital video (MPEG) using 64-QAM is possible without a significant degradation of the laser clipping rate. Measured bit error rates are compared with simulation results based on impulsive clipping noise     

H∞-optimal controller discretization

A redesign method for discretizing a continuous-time controller is proposed. The resulting hybrid control system, for example with continuous-time plant and discrete-time controller, is stable, and performance including the system's inter-sampling behaviour can be optimized by approximating some chosen reference transfer function of the continuous-time control system. In order to obtain a tractable problem, the continuous-time part of the hybrid system and the reference transfer function are approximated by a discrete-time system with arbitrary fast sampling. After lifting the resulting periodic system, the approximation problem can be formulated as a standard H_∞-problem which is solved using standard software for H_∞-controller design.     

Development of friendship reasoning: A study of interindividual differences in intraindividual change.

Structure and content aspects of interpersonal understanding in friendship reasoning (based on R. L. Selman's [1980] model) are investigated by examining microdevelopmental processes and individual differences. In a longitudinal study, 97 Icelandic subjects at 9, 12, and 15 years of age were interviewed about six issues concerning Ss' own close friendships. The sample was stratified according to gender, social class, and level of cognitive development. Results of the microdevelopmental analysis support the cumulative nature of the development of friendship reasoning. Statistically significant differences between issues were obtained for each measurement. Furthermore, prerequisite relationships among issues are observed to emerge over time. Analysis of individual differences shows that social class and level of cognitive development exert a stable influence over time on friendship reasoning. The order of development of the issues is not affected by individual differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A test of the path-goal theory of leadership with need for clarity as a moderator in research and development organizations.

A study of 477 professional employees from four research and development organizations revealed that need for clarity had a moderating effect on the initiating structure-satisfaction relationship for both concurrent and 1-year-later data, whereby the higher the need for clarity among subordinates, the stronger the relationship between initiating structure and job satisfaction. In addition, need for clarity similarly moderated the initiating structure-performance relationship in the largest of the research and development organizations for both concurrent and 1-year-later data. Neither task clarity nor organization membership had a moderator effect for these relationships. Implications for path–goal leadership theory and the management of research and development professional employees are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)