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排序方式: 共有213条查询结果,搜索用时 390 毫秒
1.
2.
Chen T.-h. Chang K.W. Bui S.B. Wang H. Dow G.S. Liu L.C.T. Lin T.S. Titus W.S. 《Microwave Theory and Techniques》1991,39(12):1980-1986
The design and fabrication of four broadband monolithic passive baluns including CPW Marchand, multilayer MS Marchand, planar-transformer and broadside-coupled line baluns are presented. Operational frequencies range from 1.5 GHz to 24 GHz. Maximum relative bandwidths in excess of 3:1 are achieved. Simulated performances using full wave electromagnetic analysis are shown to agree with the measured results. Two accurate equivalent circuit models constructed from either electromagnetic simulated or measured S-parameters are developed for the MS Marchand and transformer baluns making the optimization of baluns and circuit design using the baluns much more efficient. The design of monolithic double-balanced diode mixer using two planar-transformer baluns is also presented. Without DC bias, the mixer shows a minimum conversion loss of 6 dB with the RF at 5 GHz and a LO drive of 15 dBm at 4 GHz. The measured input IP3 of this mixer is better than 15 dBm over the 4 to 5.75 GHz frequency band 相似文献
3.
Huei Wang Kwo Wei Chang Tran L.T. Cowles J.C. Block T.R. Lin E.W. Dow G.S. Oki A.K. Streit D.C. Allen B.R. 《Solid-State Circuits, IEEE Journal of》1996,31(10):1419-1425
A family of millimeter-wave sources based on InP heterojunction bipolar transistor (HBT) monolithic microwave/millimeter-wave integrated circuit (MMIC) technology has been developed. These sources include 40-GHz, 46-GHz, 62-GHz MMIC fundamental mode oscillators, and a 95-GHz frequency source module using a 23.8-GHz InP HBT MMIC dielectric resonator oscillator (DRO) in conjunction with a GaAs-based high electron mobility transistor (HEMT) MMIC frequency quadrupler and W-band output amplifiers. Good phase noise performance was achieved due to the low 1/f noise of the InP-based HBT devices. To our knowledge, this is the first demonstration of millimeter-wave sources using InP-based HBT MMIC's 相似文献
4.
Ali B. Alamin Dow Adel Gougam Nazir P. Kherani I. W. Rangelow 《Microsystem Technologies》2014,20(4-5):955-961
The current work reports on the realization of movable micromachining devices using self-aligned single-mask fabrication process. Only dry etching process utilizing inductively coupled plasma reactive ion etching was used to release 3D micro structures from single crystal silicon substrate. No wet etching process is required to release the structures as is the case with silicon on insulator (SOI) wafers. Also the developed process does not require an SOI substrate and accordingly dispensing with the application of a wet etching step, thus yielding uniform structures without stiction. The optimized process was applied to realize thermally actuated microgrippers. The article presents the development of the fabrication process and demonstrates the operation of the fabricated device. The optimized process provides an avenue for low cost fabrication of movable micromachining devices without the use of complicated wet etching steps typically associated with SOI substrates. 相似文献
5.
A unified picture is obtained of the Cooper pair-breaking data by Cu-site Zn and Ni in Nd2–z
Ce
z
CuO4, La2–SrCuO4, Bi2Sr2CaCu2O8, Bi1.8Pb0.2Sr2Ca2Cu3O10, YBa2Cu3O7, and YBa2Cu4O8. The data are generally inconsistent with spin-fluctuation d-wave pairing mechanisms of superconductivity and with all two-dimensional cuprate-plane models. The data are consistent with superconductivity in the charge reservoirs. 相似文献
6.
The charge-transfer hypothesis is shown to be inconsistent with data for YBa2Cu3Ox: (i) The two-step behavior ofT
c(x) (with jumps from zero to 60 K and then to 90 K) is not reflected as a similar, statistically significant two-step behavior in the bond-valence-sum charge of cuprate-plane Cu ions (as once believed), (ii) as a consequence of the law of conservation of charge, the derivatives of the layer charges with respect to oxygen contentx for both the Ba-O layers and the charge-reservoir Cu-O chains have the opposite signs to those predicted, and (iii) the charge-transfer observed for superconducting YBa2Cu3Ox is not sufficient to produce superconductivity, as demonstrated by insulating PrBa2Cu3Ox, which has virtually the same layer charges. 相似文献
7.
This paper summarizes results on the use of quantitative microscopy in relating microstructural features to the friability of a model abrasive material, Al2O3-ZrO2. Quantitative stereology was used to characterize the geometric aspects of the microstructure of fused Al2O3-ZrO2 abrasives and to relate these to friability. The microstructure was controlled by varying processing parameters. The quench rate of the material from the melt was found to exhibit the most control over the microstructure. The friability was measured using three methods: the ball mill test, a DeBeers Friatester and a microfriability test developed for this study. Friability was found to be controlled by the geometric aspects of microstructure. The microstructural parameter which appeared to exert the largest influence over friability was the scale factor glα. A fracture mechanics approach was employed to explain the observed increase in strength and toughness in Al2O3-ZrO2 materials. 相似文献
8.
J. Maxwell Dow Lynn M. Naughton Birte Hollmann Shi-Qi An Robert P. Ryan 《Israel journal of chemistry》2016,56(5):321-329
Bacterial cell-to-cell signals of the diffusible signal factor (DSF) family are cis-2-unsaturated fatty acids that differ in their chain length and branching patterns. Signaling involving DSF family members occurs in diverse bacteria to include plant and human pathogens. In the majority of these organisms, the perception of DSF is linked to turnover of the second messenger cyclic di-GMP by one of two “core” pathways. Additional “accessory” signal transduction pathways can also be found, but are not widely conserved. DSF signaling acts to regulate diverse functions to include biofilm formation and architecture, antibiotic resistance, and the production of virulence factors in pathogens. DSF family signals can also participate in interspecies signaling with other bacteria and interkingdom signaling with the yeast Candida albicans. Such interactions may have importance in modifying microbial behavior during polymicrobial infections. 相似文献
9.
Sudhanshu K. Semwal J. Karl Armstrong Douglas E. Dow Fumio E. Maehara 《The Visual computer》1994,10(7):388-406
Most parts of the human body are cylindrical in shape. Generalized cylinders, with two cross-sectional openings, are a logical choice to represent these cylindrical shapes. However, a variety of human body regions can be visualized as surfaces with multiple openings or multimouth (MM) surfaces. Some examples of such surfaces are the pelvis, the chest, and the palms of the hands. We investigated the suitability of non-uniform rational B-spline (NURBS) formulation for creating multimouth surfaces. Two techniques, the surface wrapping model and the garland model, are presented. 相似文献
10.
The ruthenate compounds, Gd2–zCe
z
Sr2Cu2RuO10, GdSr2Cu2RuO8, and doped Sr2YRuO6, all superconduct in their SrO layers, which is why they have almost the same 49 K onset temperatures for superconductivity. The sister compound Ba2GdRuO6, either doped or not, does not superconduct, because L = 0, J 0 Gd breaks pairs and destroys superconductivity in the potentially superconducting BaO layers. High-temperature superconductivity resides in the SrO or BaO layers, or in interstitial-oxygen regions of the crystal, not in the cuprate-planes. 相似文献