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21.
This is the second of two papers describing a procedure for the three-dimensional nonlinear time-history analysis of steel-framed buildings. An overview of the procedure and the theory for the panel zone element and the plastic hinge beam element are presented in part I. In this paper, the theory for an efficient new element for modeling beams and columns in steel frames called the elastofiber element is presented, along with four illustrative examples. The elastofiber beam element is divided into three segments—two end nonlinear segments and an interior elastic segment. The cross sections of the end segments are subdivided into fibers. Associated with each fiber is a nonlinear hysteretic stress-strain law for axial stress and strain. This accounts for coupling of nonlinear material behavior between bending about the major and minor axes of the cross section and axial deformation. Examples presented include large deflection of an elastic cantilever beam, cyclic loading of a cantilever beam, pushover analysis of a 20-story steel moment-frame building to collapse, and strong ground motion analysis of a two-story unsymmetric steel moment-frame building. 相似文献
22.
Anthony P. Zilko J. Pawlik J. Swaminathan V. Hartman R. 《Quantum Electronics, IEEE Journal of》1982,18(7):1094-1100
Device characteristics of double heterostructure lasers with Al0.4 Ga0.6 As confinement layers and GaAs0.99 Sb0.01 active layers are presented. Average emission wavelengths have been increased from 0.87 μm for undoped active layers to 0.88 μm for2 times 10^{17} cm-3Ge doped active layers with a "wash" melt preceding the growth of the active layer and to 0.89 μ for1 times 10^{18} cm-3Mg doped active layers grown following a "wash" melt. Threshold currents for lasers from 21 wafers are examined for several growth conditions and compared with Al0.08 Ga0.92 As active layer devices. Device resistance, external quantum efficiency, device degradation, and pulsed and CW threshold currents as a function of temperature are also discussed. 相似文献
23.
A review of the nature of solar radiation and the spectral distribution of its energy is presented. The attenuation of solar radiation by scattering and absorption and the effects of atmospheric pollutants on radiation attenuation with an estimate of the long-term effects of pollutants is discussed. 相似文献
24.
A Mixed Integer Stochastic Optimization Model for Settlement Risk in Retail Electric Power Markets 总被引:1,自引:1,他引:0
Gabriel Steven A. Kiet Supat Balakrishnan Swaminathan 《Networks and Spatial Economics》2004,4(4):323-345
Recent changes in the U.S. electric power markets have contributed to volatility in hourly prices and loads. In this paper we consider the position of the electric power retailer who typically contracts with suppliers and end-users and must provide future load requirements to the suppliers. As part of this energy supply chain, the retailer is faced with great uncertainty in both market prices as well as end-user loads. Based on actual data for the PJM market covering Pennsylvania, New Jersey, and Maryland, we develop a probabilistic optimization model to optimize the net profits for the retailer for a forecast time horizon (typically one or more hours) given the cumulative performance in previous time periods (hours). The resulting model is formulated as a mixed integer linear program with binary variables due to the disjunctive nature of certain forward load estimation bandwidth tolerance constraints. In addition, we also provide an existence result to this optimization model. Lastly, we present a numerical example of the optimization model to validate its workings and provide some insight into model sensitivities. 相似文献
25.
A fast-settling adaptive calibration technique is presented that makes phase noise cancelling DeltaSigma fractional-N PLLs practical for the low reference frequencies commonly used in wireless communication systems. The technique is demonstrated as an enabling component of a 2.4 GHz ISM band CMOS PLL IC with a 730 kHz bandwidth, a 12 MHz reference, and an on-chip loop filter. In addition to the adaptive calibration technique, the IC incorporates a dynamic charge pump biasing technique to reduce power dissipation. The worst-case phase noise of the IC is -101 dBc/Hz and -124 dBc/Hz at 100 kHz and 3 MHz offsets, respectively, and the adaptive phase noise cancellation technique has a worst-case settling time of 35 mus . The IC is implemented in 0.18 CMOS technology. It measures 2.2 x 22 mm2 and its core circuitry consumes 20.9 mA from a 1.8 V supply. 相似文献
26.
Co-planar lines on silicon substrates with and without slow-wave effect are characterized using time-domain reflectometry (TDR) and vector network analyzer (VNA) measurements, and simulated using a proposed nonphysical resistance-inductance-conductance-capacitance (RLGC) model. The silicon co-planar lines are characterized based on comparison to package transmission lines. Co-planar silicon lines without slow-wave mode are modeled in the same way as package transmission lines, but co-planar lines with slow-wave mode are modeled in a different way from package transmission lines. Hence, a nonphysical RLGC model including slow-wave mode is proposed along with the extraction method from VNA measurements. Simulation results correlate well with time- and frequency-domain measurements for the co-planar silicon lines. 相似文献
27.
U. Vijayalakshmi M. Chellappa U. Anjaneyulu Geetha Manivasagam Swaminathan Sethu 《Materials and Manufacturing Processes》2016,31(1):95-106
The purpose of this study is to synthesize and characterize nanosized titania (TiO2), zinc oxide (ZnO), and its composite coating on Ti–6Al–4V to enhance its corrosion protection behavior in Ringer's solution. Nanosized powders of TiO2 and ZnO was characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy - energy dispersive atomic spectroscopy (SEM-EDAX) analysis. As a result of antibacterial activity, both ZnO and TiO2/ZnO have produce remarkable inhibition zone on Escherichia coli. The antibacterial activity of composites are due to the combined effect of ZnO on TiO2. The adherence and surface uniformity of TiO2/ZnO composite film on titanium implant was examined by optical microscopy and Vickers microhardness test. Corrosion resistant behavior of the coating on titanium implant was investigated by tafel polarization and impedance analysis. The composite coatings on Ti–6Al–4V have produced improved corrosion resistance with a pronounced shift in the anodic corrosion potential (Ecorr) with a corresponding less corrosion current density (Icorr) compared to monophase coating. Similar results have been obtained for impedance analysis which indicated a reduction in double layer capacitance (Cdl) and with enhancement in charge transfer resistance (Rct). These observations suggest improved corrosion resistance property of TiO2/ZnO composite coating on Ti–6Al–4V. 相似文献
28.
P. V. Prabhakaran K. J. Sreejith B. Swaminathan S. Packirisamy K. N. Ninan 《Journal of Materials Science》2009,44(2):528-533
Phenol-furfuraldehyde (PFu) resin synthesized in our laboratory was characterized for its thermal properties and mixed with
elemental silicon and the mixture was evaluated as precursor for SiC ceramics. The mix on sintering at 1,500 °C gave nano-SiC
powder. The sintering experiment carried out in flowing argon has also resulted in the formation of SiC wires/fibers having
diameter in nano to sub-micron range. 相似文献
29.
Pannala S. Bandyopadhyay J. Swaminathan M. 《Advanced Packaging, IEEE Transactions on》1999,22(3):249-258
This paper discusses the pulse propagation effects on lossy thin film planes. The ground bounce phenomena produced by the resonance on planes has been captured using a combination of modeling techniques and measurements. Macromodeling method has been used to explain the transient phenomena on planes by using the dominant poles and residues of the system 相似文献
30.
An onboard hydrogen generation method based on hydrides and water recovery for micro-fuel cells 总被引:1,自引:0,他引:1
Micro-proton exchange membrane fuel cells are considered to be the next generation power sources for micro-scale power applications, but onboard hydrogen storage and generation with high energy density at the small scale is still a technical barrier. This paper introduces a hydrogen generation method based on an onboard hydride fuel and a byproduct water recovery mechanism for micro-hydrogen PEM fuel cells. The water recovery is carried out by water diffusion from the more humid cathode side to the less humid anode side through the proton exchange membrane. The micro-fuel cells based on this water recovery method were constructed and tested. The results demonstrate that the relative humidity has a significant affect on the fuel cell performance as well as the opening area on the cover layer, the type of hydrides, and the thickness of the Nafion membrane also can affect the fuel cell performance. A 10 mm3 prototype water recovery micro-fuel cell has been built and tested, and the device has produced a maximum power density of 104 W L−1 and a maximum energy density of 313 W h L−1. 相似文献