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101.
102.
103.
Quadrifilar loop antenna 总被引:2,自引:0,他引:2
A new quadrifilar antenna has been developed for generating circularly polarized backfire radiation. The antenna consists of two orthogonal rectangular conducting loops, each incorporating capacitive coupling and fed using either a single or two coaxial cables. Though the geometry is much simpler than a conventional quadrifilar helix antenna, the radiation pattern performance is very similar. Measured and simulated patterns are compared for two antennas with different feed arrangements. It is shown that the resonant structure can produce a cardioid pattern with a directivity of 4.5 dB (120/spl deg/ 3 dB beamwidth) and a front-to-back ratio of more than 20 dB at the center operating frequency. A 10% impedance bandwidth (VSWR<2) over which the axial ratio is less than 3 dB is demonstrated. 相似文献
104.
Taxonomy of Distributed Event-Based Programming Systems 总被引:2,自引:0,他引:2
105.
Cahill Shawn P.; Zoellner Lori A.; Feeny Norah C.; Riggs David S. 《Canadian Metallurgical Quarterly》2004,72(3):543
M. Cloitre, K. Koenen, L. R. Cohen, and H. Han (2002; see record 2002-18226-001) presented results of a randomized trial that clearly demonstrate the safety and efficacy of a treatment program delivering skills training in affective and interpersonal regulation (STAIR) prior to conducting imaginal exposure (IE) to trauma memories for adults with posttraumatic stress disorder (PTSD) related to childhood abuse. In this comment the authors review the results presented by Cloitre et al and specifically compare the impact of the STAIR and IE phases of the treatment on affect regulation and psychopathology measures. Evidence for adverse events associated with exposure therapy is reviewed. The authors emphasize that the present study should not be interpreted as evidence that pretreatment with STAIR is additively helpful or necessary prior to IE for PTSD associated with child abuse and that a between-groups comparison is necessary before such conclusions can be drawn. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
DR Cahill 《Canadian Metallurgical Quarterly》1998,11(5):346-348
A previously unreported anomalous thymic artery that branched from the anterior aspect of right common carotid artery approximately 1 cm above bifurcation of the brachiocephalic artery was found during routine dissection. It traveled inferiorly through a plexus of inferior thyroid veins for 6 cm in front of the brachiocephalic artery and crossed the anterior surface of the trachea where it divided into two branches that supplied the right and left lobes of the thymus. The development and blood supply of the thymus and their clinical anatomy are reviewed. 相似文献
107.
Within 3 hours of induction of acute hydrocephalus in a canine model, lateral ventricular CSF pressure increased from an initial average of 14.6 +/- 2.8 cm H2O to 40.2 +/- 5.7 cm H2O. Ventricular volumes, as measured from MR images, increased 1.45 +/- 0.94 cm3, 1.92 +/- 0.82 cm3, and 2.24 +/- 0.60 cm3 after 6, 24, and 48 hours, of hydrocephalus, respectively. This canine model was reliable and consistent with clinical conditions. 相似文献
108.
Li R.L. Tentzeris E.M. Laskar J. Fusco V.F. Cahill R. 《Microwave and Wireless Components Letters, IEEE》2002,12(8):305-307
A rectangular loop antenna is proposed for DCS-1800 and IMT-2000 mobile phone handsets. By introducing a small gap in the wire loop, an impedance bandwidth of 24% can be achieved. The antenna mounted on a metal box is simulated using the FDTD method. It is found that the introduction of a small gap also results in a radiation pattern with desirable polarization independence and a reduced gain in the direction of the user's head. The simulated and measured results are presented. 相似文献
109.
Effect of Road Surface,Vehicle, and Device Characteristics on Energy Harvesting from Bridge–Vehicle Interactions
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Paul Cahill Vesna Jaksic John Keane Anthony O'Sullivan Alan Mathewson Shaikh Faruque Ali Vikram Pakrashi 《Computer-Aided Civil and Infrastructure Engineering》2016,31(12):921-935
Energy harvesting to power sensors for structural health monitoring (SHM) has received huge attention worldwide. A number of practical aspects affecting energy harvesting and the possibility of health monitoring directly from energy harvesters is investigated here. The key idea is the amount of power received from a damaged and an undamaged structure varying and the signature of such variation can be used for SHM. For this study, a damaged bridge and an undamaged bridge are considered with harvesters located at different positions and the power harvested is accessed numerically to determine how energy harvesting can act as a damage detector and monitor. Bridge–vehicle interaction is exploited to harvest energy. For a damaged bridge, a bilinear breathing crack is considered. Variable surface roughness according to ISO 8606:1995(E) is considered such that the real values can be considered in the simulation. The possibility of a drive‐by type health monitoring using energy harvesting is highlighted and the effects of road surface on such monitoring are identified. The sensitivity of the harvester health monitoring to locations and extents of crack damage are reported. This study investigates the effects of multiple harvesters and the effects of vehicular parameters on the harvested power. Continuous harvesting over a length of the bridge is considered semianalytically. A comparison among the numerical simulations, detailed finite element analysis, and experimental results emphasizes the feasibility of the proposed method. 相似文献
110.
Acrolein, a volatile, unsaturated aldehyde, is a known respiratory toxicant and one of the 188 most hazardous air pollutants identified by the U.S. EPA. A newly developed analytical method was used to determine residential indoor air concentrations of acrolein and other volatile aldehydes in nine homes located in three California counties (Los Angeles, Placer, Yolo). Average indoor air concentrations of acrolein were an order of magnitude higher than outdoor concentrations at the same time. All homes showed similar diurnal patterns in indoor air concentrations, with acrolein levels in evening samples up to 2.5 times higherthan morning samples. These increases were strongly correlated with temperature and cooking events, and homes with frequent, regular cooking activity had the highest baseline (morning) acrolein levels. High acrolein concentrations were also found in newly built, uninhabited homes and in emissions from lumber commonly used in home construction, suggesting indoor contributions from off-gassing and/or secondary formation. The results provide strong evidence that human exposure to acrolein is dominated by indoor air with little contribution from ambient outdoor air. 相似文献