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991.
A wideband miniature G-shaped coplanar waveguide fed dual-band antenna for a wireless local area network (WLAN) is proposed. The proposed antenna has good radiation pattern and can provide two separate measured impedance bandwidths of 0.55 GHz (about 22.9% centred at 2.42 GHz) and 2.85 GHz (about 50.9% centred at 5.60 GHz), so that it easily covers the required bandwidths for WLAN operation. This design results in a small antenna size of 22 times 18.5 mm with the ground plane regarded as part of the antenna structure. 相似文献
992.
G. A. Shanshurov 《Russian Electrical Engineering》2007,78(9):467-473
A model of an induction motor with an asymmetric stator winding is developed; it may be represented as two phases connected in parallel or in series and displaced is space by some angle. 相似文献
993.
Jing Wang Walker D.M. Xiang Lu Majhi A. Kruseman B. Gronthoud G. Villagra L.E. van de Wiel P.J.A. Eichenberger S. 《Design & Test of Computers, IEEE》2007,24(3):226-234
Excessive power supply noise during test can cause overkill. This article discusses two models for supply noise in delay testing and their application to test compaction. The proposed noise models avoid complicated power network analysis, making them much faster than existing power noise analysis tools. can cause performance degradation and 相似文献
994.
An analytical current-voltage (I -V ) model for planar-doped HEMTs is developed. This compact model covers the complete range of I -V characteristics, including the current saturation region and parasitic conduction in the electron-supplying layer. Analytical expressions for the small-signal parameters and current-gain cutoff frequency are derived from the I -V model. Modeling results for a 0.1-μm-gate planar-doped AlInAs-GaInAs HEMT show excellent agreement with measured characteristics. Threshold voltages and parasitic conduction in planar-doped and uniformly doped HEMTs are also compared and discussed 相似文献
995.
An experimental balanced optical second-order phase-locked loop constructed using 1320 nm diode laser pumped miniature Nd:YAG lasers is discussed. The loop is stable and has a phase error of less than 1.8° when the received signal power is -65 dBm or more. The phase error appears to be dominated by the lasers' frequency noise as long as the signal power is more than -60 dBm 相似文献
996.
Young-of-the-year spottail shiners (Notropis hudsonius) were used as biomonitors to determine the spatial distribution (1982/83) and assess trend data for organochlorine and mercury residues. Significantly (p < 0.01) higher PCB residues were found in Detroit River spottail shiners than in collections from southwestern Lake St. Clair and northwestern Lake Erie. The highest PCB residues were found in the west bank collections from Michigan waters (912–2,997ng/g) compared to the mid-stream (96–290 ng/g) and east bank collections (153–316 ng/g). Chlordane residues were found to be elevated in all spottail shiner samples from urbanized areas. Octachlorostyrene and ∑ DDT residues were distributed uniformly within the study area, whereas mercury concentrations were found to be lower in spottail shiners from northwestern Lake Erie than in comparable samples from the Detroit River and southwestern Lake St. Clair. Residues for BHC, heptachlor, aldrin, and chlorinated benzenes were near their detection limits; mirex and chlorinated phenols were not detectable. Recent (1982/83) PCB residue levels in spottail shiners exceeded the IJC aquatic life objective (Great Lakes Water Quality Agreement of 1978) at all the sites sampled, except at Pike Creek in Lake St. Clair. PCB residues in spottail shiners from Pike Creek, Big Creek, and Leamington have declined significantly (p < 0.01) since the mid-seventies. Mercury and chlordane residues have decreased in spottail shiner samples from Leamington, but have remained virtually unchanged at Big Creek and Pike Creek. 相似文献
997.
We report on compound formation in the system HgCdTeO. Samples were prepared by solid state reaction of mixtures of the binary oxide components. Specific phases were identified and characterized by X-ray and microprobe techniques. For some of these compounds small single crystals could be prepared and structural data of which are reported. Three groups of phases could be distinguished, most of them being of low symmetry, with Te in +4, +6, and in mixed oxidation states. The monotellurites HgTeO3 and CdTeO3 are structurally different and exhibit a large miscibility gap, whereas for the di-tellurites complete solid solution between CdTe2O5 and HgTe2O5 was found. As to the tellurates, phases with the compositions MTeO4 and M3Te2O9 (M = Hg, Cd) have been prepared. The Cd3Te2O9-structure is stabilized by 30 mole% Hg. Another tellurate, monoclinic Hg2TeO4, was found to be isomorphous to the respective selenate and sulfate and is identical with the mineral magnolite. The interaction of Te2O5 with the metal oxides led to the formation of mixed valence compounds with both Te(+4) and Te(+6) of the types M2Te2O7 and MTe2O6. 相似文献
998.
G. Kessler 《Progress in Nuclear Energy》2002,40(3-4):309-325
Nuclear energy must compete against other energy technologies in the 21st century. It must be economical and it must be proven that it fulfills the conditions for sutainability. This means that the requirements of — no short term depletion of resources — extremely low emission of noxious or radioactive substances to the environment — extremely low release of radioactivity from a nuclear plant in case of the most severe accidents and — the present very long term problem of high active waste must be transformed into a few hundred years problem through destruction of plutonium, transmutation of the minor actinides and the most important very long lived fission products. 相似文献
999.
A. Cardador-Martí nez E. Casta o-Tostado G. Loarca-Pi a 《Food Additives & Contaminants》2002,19(1):62-69
Polyphenols with antimutagenic and anticarcinogenic properties are present in fruits, vegetables and legumes. In this study, the Salmonella typhimurium tester strains TA98 and TA100 were used in the microsuspension assay to examine the antimutagenic effect of phenolic compounds extracted from the common bean (Phaseolus vulgaris) against mutagenicity induced by aflatoxin B 1 (AFB 1 ). A dose-response curve was constructed for AFB 1 ; from which a level of 40ng AFB 1 /tube was selected for all antimutagenicity assays. The AFB 1 and phenolic extract (PE) were not toxic to the bacteria at concentrations tested. In the case of PE, results were similar to the number of spontaneous revertants for TA98 and TA100. The inhibitory effect of PE against AFB 1 mutagenicity was dose-dependent at the lower concentrations tested (2.5, 5, 10, 12.5, 15 and 25 μg-equivalent ( + )-catechin/tube for TA98; 0.5, 1, 1.5, 2.5, 5, 10 and 25 μg-equivalent ( + )-catechin/ tube for TA100). Further, a two-stage incubation procedure was used to investigate the potential interaction between PE and AFB 1 . The greatest inhibitory effect of the PE on AFB 1 mutagenicity occurred when PE and AFB 1 were incubated together. When the bacteria were first incubated with PE followed by a second incubation with AFB 1 , lower inhibition was observed. Lower inhibition was also observed when the bacteria were first incubated with AFB 1 followed by a second incubation with PE. The results suggest that the mechanism of inhibition could involve the formation of a chemical complex between of PE and AFB 1 . 相似文献
1000.