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Several Designs (several + design)
Selected AbstractsRF MEMS impedance tuners for 6,24 GHz applicationsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2007Tauno Vähä-Heikkilä Abstract RF MEMS tuners with wide impedance coverage have been developed for 6,24 GHz noise parameter and load-pull measurement systems. The tuners are based on triple-, double-, and single-stub topologies loaded with switched MEMS capacitors. Several designs are presented, and they use 10,13 switched MEMS capacitors to produce 1024,8192 (210,213) different impedances. The measured impedance coverage agrees well with simulations and it is the widest ever measured impedance coverage from any planar tuner to-date. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007. [source] Palatal plate of different designs for the suppression of masseter muscle activity during sleep.JOURNAL OF ORAL REHABILITATION, Issue 9 2002A challenge to the concept of placebo splint Several designs of palatal appliance have been reported for the treatment of craniomandibular disorders. However, the effect of these appliances has not yet been fully clarified. This study aimed to reveal the effect of palatal appliances of different design on masseter muscle activity during sleep. Four volunteers (three women and one man, mean age 36·0 years) were used in this study. For each subject, four different types of palatal appliances were used. The palatal appliances were (1) horse shoe type (1 mm thick), (2) thin appliance which covered the whole palate (1 mm thick), (3) thick appliance which filled the palatal concavity and (4) appliance with half the thickness of the third appliance. These appliances were worn for 1 week in a randomized sequence with 1-week interval between each appliance. Right masseter muscle EMG was recorded three nights per week at home. The EMG signal longer than 0·25 s was classified as a burst and a signal shorter than 0·25 s was classified as a brief burst of fragmentary myoclonus (FM). Mean number of burst per hour for four subjects were 7·99 ± 7·32, 3·52 ± 1·95, 5·90 ± 3·99, 2·87 ± 2·87 and 9·96 ± 6·02 for base line, appliance 1, 2, 3 and 4, respectively. Mean number of FM per hour were 136·86 ± 69·88, 90·53 ± 41·19, 99·49 ± 39·29, 71·66 ± 24·66 and 144·39 ± 42·97, respectively. From these results, it was suggested that the thick palatal appliance suppressed the masseter muscle activity during sleep most effectively. Also, the results for appliance 4 questioned the concept of placebo effect for non-occlusal appliances. [source] Interaction of separation and reactive stages on ETBE reactive distillation columnsAICHE JOURNAL, Issue 3 2004Budi H. Bisowarno Abstract Reactive distillation is a favorable alternative to conventional series of reactor-distillation processes for ether productions. However, the design of such columns is complicated due to the interaction between vapor-liquid equilibrium and reaction rates. There are conflicting reports on whether adding excessive separation stages degrade the column performance. A comparison is made of several designs of single and double feed reactive distillation columns for ETBE production to investigate the effects of separation and reaction stages on the overall performance. The explanations are presented using simulation results, whose mathematical models are written in the Aspen Plus environment. The results confirm that a conservative approach by adding extra separation and reaction stages can be applied to reactive distillation design. However, output multiplicity may be observed for longer column and should be considered in the early design phase. © 2004 American Institute of Chemical Engineers AIChE J, 50: 646,653, 2004 [source] 96-Channel receive-only head coil for 3 Tesla: Design optimization and evaluationMAGNETIC RESONANCE IN MEDICINE, Issue 3 2009Graham C. Wiggins Abstract The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive-only phased-array head coil with 96 receive elements constructed on a close-fitting helmet-shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal-to-noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g -factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32-channel array built on an identical helmet-shaped former and to a larger commercial 12-channel head coil. The 96-channel coil provided substantial SNR gains in the distal cortex compared to the 12- and 32-channel coils. The central SNR for the 96-channel coil was similar to the 32-channel coil for optimum SNR combination and 20% lower for root-sum-of-squares combination. There was a significant reduction in the maximum g -factor for 96 channels compared to 32; for example, the 96-channel maximum g -factor was 65% of the 32-channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Optimal designs for calibration of orientationsTHE CANADIAN JOURNAL OF STATISTICS, Issue 3 2007Hwashin H. Shin Abstract This paper concerns designed experiments involving observations of orientations following the models of Prentice (1989) and Rivest &Chang (2006). The authors state minimal conditions on the designs for consistent least squares estimation of the matrix parameters in these models. The conditions are expressed in terms of the axes and rotation angles of the design orientations. The authors show that designs satisfying U1 + , + Un = 0 are optimal in the sense of minimizing the estimation error average angular distance. The authors give constructions of optimal n -point designs when n , 4 and they compare the performance of several designs through approximations and simulation. Plans d'expérience optimaux pour la calibration d'orientations Cet article concerne la planification d'expériences dans le cadre des modèles de Prentice (1989) et de Rivest &Chang (2006) pour des mesures d'orientation. Les auteurs donnent des conditions minimales qu'un plan expérimental doit respecter pour que l'estimation des moindres carrés des paramètres matriciels de ces modèles soit convergente. Ces conditions s'expriment en fonction des axes et des angles des matrices de rotation du plan. Les auteurs montrent que les plans tels que U1 + , + Un = 0 sont optimaux au sens oú la distance angulaire moyenne des erreurs d'estimation est minimisée. Ils précisent la forme des plans optimaux à n , 4 points et comparent la performance de divers plans au moyen d'approximations et de simulations. [source] Making Efficient Use of Patients in Designing Phase III Trials Investigating Simultaneously a Set of Targeted Therapies with Different TargetsBIOMETRICAL JOURNAL, Issue 6 2006Werner Vach Abstract Targeted therapies are a recent development in cancer treatment research. As these therapies can only be administered to patients with certain individual characteristics, it is a straightforward idea to investigate several of such therapies simultaneously in a given patient population in order to compare each targeted therapy with the current standard therapy. This raises the question how patients satisfying several characteristics should be handled. We consider in this paper several designs to allocate treatments in a random manner to these patients, such that the evaluation of each single targeted therapy can be based on a simple comparison of patients receiving the targeted therapies versus those receiving the standard therapy within a well defined subgroup of patients satisfying the corresponding characteristic. We show how one can ensure that patients with several characteristics can contribute simultaneously to the evaluation of several targeted therapies and that this is the key point for an efficient use of the patients available. We further discuss some ethical and practical issues in applying the new designs and outline strategies to evaluate the overall effect of all targeted therapies together. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||