排序方式: 共有17条查询结果,搜索用时 31 毫秒
1.
Banerjee S.R. Chenglin Zheng Drayton R.F. 《Advanced Packaging, IEEE Transactions on》2007,30(2):200-208
Microstrip interconnects with a V conductor are designed, fabricated, and measured to provide a compact solution for designs requiring low characteristic impedance lines. S-parameter curves are shown up to 35 GHz for 0.5-cm-long lines. The 308-mum-deep V structure produces a 33.8-Omega line with strong standing waves and reflections under 5 dB. To further reduce the impedance, a partial shield is added that results in 6.7 times reduction of signal line width, near elimination of open-end effect, and excellent correlation with a standard 15-Omega microstrip up to 25 GHz. A filter demonstration shows near ideal behavior in the 3 dB response and low return loss when compared to a similar conventional design. 相似文献
2.
Micromachined filters on synthesized substrates 总被引:3,自引:0,他引:3
Drayton R.F. Pacheco S.P. Katehi L.P.B. Wang J. Yook J.-G. 《Microwave Theory and Techniques》2001,49(2):308-314
Effective high-frequency spectrum usage requires high-performance filters to have a sharp cutoff frequency and high stopband attenuation. Stepped-impedance low-pass designs achieve this function best with large ratios of high-to-low-impedance values. In high-index materials, such as Si (11.7) and GaAs (12.9), however these high-to-low-impedance ratios are around five, thereby significantly limiting optimum filter performance. This paper characterizes the use of Si micromachining for the development of synthesized substrates, which, when utilized appropriately, can further reduce the low-impedance value or increase the high-impedance value. Both designs have demonstrated high-to-low-impedance ratios that are 1.5-2 times larger than conventional techniques 相似文献
3.
Muir Wood R Drayton M Berger A Burgess P Wright T 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2005,363(1831):1407-1422
Probabilistic catastrophe loss modelling techniques, comprising a large stochastic set of potential storm-surge flood events, each assigned an annual rate of occurrence, have been employed for quantifying risk in the coastal flood plain of eastern England. Based on the tracks of the causative extratropical cyclones, historical storm-surge events are categorized into three classes, with distinct windfields and surge geographies. Extreme combinations of "tide with surge" are then generated for an extreme value distribution developed for each class. Fragility curves are used to determine the probability and magnitude of breaching relative to water levels and wave action for each section of sea defence. Based on the time-history of water levels in the surge, and the simulated configuration of breaching, flow is time-stepped through the defences and propagated into the flood plain using a 50 m horizontal-resolution digital elevation model. Based on the values and locations of the building stock in the flood plain, losses are calculated using vulnerability functions linking flood depth and flood velocity to measures of property loss. The outputs from this model for a UK insurance industry portfolio include "loss exceedence probabilities" as well as "average annualized losses", which can be employed for calculating coastal flood risk premiums in each postcode. 相似文献
4.
Albert X. Wu James A. Drayton Zachary P. Smith 《American Institute of Chemical Engineers》2019,65(12):e16700
Perfluoropolymers have fundamentally distinct thermodynamic partitioning properties compared to those of their hydrocarbon counterparts. However, current upper bound theory assumes hydrocarbon solubility behavior for all polymers. Herein, the fundamental presupposition of invariance in solubility behavior to upper bound performance is critically assessed for perfluoropolymers and hydrocarbon polymers. By modifying solubility relationships, theoretical perfluoropolymer upper bounds are established, showing a positive shift of the upper bound front as a result of beneficial solubility selectivities for certain gas pairs, including N2/CH4, He/H2, He/N2, He/CH4, and He/CO2. Within the framework of the solution–diffusion model, an analysis is presented to compare two independent approaches often pursued in efforts to surpass the polymer upper bound: (a) achieving solubility selectivity via perfluoropolymers and (b) improving diffusion selectivity via rigid hydrocarbon polymers. This analysis demonstrates the significant benefit that can be achieved by considering both the chemical composition and morphology of solid-state macromolecules when designing membrane materials. 相似文献
5.
A custom-designed silicon-based 50-GHz interconnect is integrated for packaging demonstrations of broadband optoelectronic (OE) applications in silicon optical microbench technology. The half-shielded (or partially shielded) 0.5-cm interconnect has 25-dB isolation and 0.9-dB transmission loss over 50 GHz. When implemented in this packaged architecture, the nature of the interconnect minimizes coupling and eliminates the need for an external test fixture that is prevalent in a more conventional approach. The interconnect is further demonstrated in a multiport electrical package to illustrate the potential of this architecture up to 40-Gb data rates, and the resulting package has insertion loss less than 5 dB at 50 GHz. 相似文献
6.
Improved Transmission Representations in Oligopolistic Market Models: Quadratic Losses, Phase Shifters, and DC Lines 总被引:2,自引:0,他引:2
Hobbs B.F. Drayton G. Bartholomew Fisher E. Lise W. 《Power Systems, IEEE Transactions on》2008,23(3):1018-1029
7.
High-frequency planar circuits experience large electromagnetic (EM) coupling in dense circuit environments. As a result, individual components exhibit performance degradation that ultimately limits overall circuit response. This paper addresses crosstalk in planar microstrip lines by evaluating micromachined packages as a means to reduce coupling. Microstrip lines with straight and meandering paths can exhibit crosstalk coupling as high as -20 dB (i.e., when placed in a side-by-side arrangement). From our study, inclusion of a monolithic package reduces this effect by as much as: -30 dB and, consequently, offers the requisite electrical and environmental protection in addition to shielding of individual elements from parasitic radiation. Presented herein is the development of the micromachined package for microstrip geometries. Included in the discussion are crosstalk effects between straight and bending geometries in open and packaged configurations and an evaluation of package noise characteristics. A packaged antenna element is also included as a demonstration of the potential use of micromachined packaging in array applications 相似文献
8.
Nancy A. Marley Jeffrey S. Gaffney Paul J. Drayton Mary M. Cunningham Kent A. Orlandini Rajendra Paode 《Aerosol science and technology》2013,47(6):569-583
Lead-210 and 210 相似文献
9.
Drayton R.F. Banerjee S.R. Haley J.L. 《Antennas and Propagation, IEEE Transactions on》2002,50(5):693-697
Micromachined transitions are characterized with abrupt and taper dielectric and conductor discontinuities. Constant impedance designs are studied for interconnects printed on the same substrate that traverse two different substrate heights. The best transition, when compared to the constant height design, has better than 20 dB return loss over 40 GHz. Its effective dielectric constant variation is less than 0.25 dB across the bandwidth, which indicates a low dispersion interconnect design with a micromachined transition 相似文献
10.
High efficiency, magnetron sputtered CdS/CdTe solar cells 总被引:1,自引:0,他引:1
Alvin D. Compaan Akhlesh Gupta Sunghyun Lee Shanli Wang Jennifer Drayton 《Solar Energy》2004,77(6):815-822
Polycrystalline II–VI semiconductor materials show great promise for efficient, low-cost photovoltaics. Large-area deposition of the II–VI semiconductors such as CdTe is possible by a variety of methods but the use of a plasma-based method such as magnetron sputtering can have significant advantages. Here we present recent results in the fabrication of CdS/CdTe cells using rf magnetron sputtering and discuss some of the advantages that accrue from the use of sputtering methods in this class of materials. Some of these advantages are particularly relevant as the polycrystalline thin-film PV community addresses issues related to the fabrication of tandem cells with efficiencies over 25%. Our best results have been obtained with sputtered ZnO:Al to achieve a CdTe solar cell having 14.0% efficiency at one sun with an air mass 1.5 global spectrum. We have also studied reactive sputtering of ZnTe:N which shows promise for use as a transparent back contact or as a recombination junction with ZnO:Al for II–VI based alloy top cells in a tandem solar-cell configuration. Finally, some advances have been made in substrate-configuration CdTe cells on Mo using sputter deposition that hold promise for flexible CdTe-based PV. 相似文献