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131.
Integration of Singularities in FE/BE Analyses of Soil-foundation Interaction with Non-homogeneous Elastic Soils 总被引:1,自引:0,他引:1
Rudolf F. Stark 《Meccanica》2001,36(4):329-350
This paper addresses the derivation of the boundary integral equations for a non-homogeneous elastic half-space subjected to constant surface tractions on an arbitrarily shaped area on the basis of the respective Green's functions. The type of non-homogeneity considered is a power law variation of Young's modulus with depth below the surface of the half-space. Two different methods, a contour integral and an integration-free approach are presented, applicable for arbitrarily and rectangular shaped boundary elements, respectively. In the first one the divergence theorem is used in order to reduce the integration of a two-dimensional surface element to an integration over the element's confining boundary only. In the second approach no integration at all is needed since the solution is found simply by evaluating functions to be determined at the boundaries of the loaded rectangle. 相似文献
132.
133.
Ahmad Ahmeda Mohammad Mahdi Zangeneh Shirin Mansooridara Zahra Malek Akram Zangeneh 《应用有机金属化学》2020,34(3):e5355
Metallic nanoparticles have gained significant attention in the area of biomedical technology. Because of its high surface area, metallic nanoparticles are being widely used in various fields including the medical and engineering sciences. One of the valuable applications of metallic nanoparticles especially copper, zinc, and iron nanoparticles is increasing the physiological function of central nervous system. Besides, Iranian people are using the Salvia chloroleuca for neuroprotective properties. In the present research, iron nanoparticles were biosynthesized by S. chloroleuca leaf aqueous extract as reducing and stabilizing agents. Also, we revealed the protective effect of FeNPs in methadone-treated PC12 cells. FeNPs were characterized and analyzed using common nanotechnology techniques including FT-IR, UV–Vis. spectroscopy; EDS, TEM, and FE-SEM. TEM and FE-SEM images revealed a uniform spherical morphology for FeNPs. In the biological part of the current study, the both treatments of FeNPs significantly (p ≤ 0.01) reduced the cell cytotoxicity and cell death index as well as increased the cell viability and cell proliferation in methadone-treated PC12 cells. In these treatments, mitochondrial membrane potential significantly (p ≤ 0.01) increased compared to methadone-induced PC12 cells. DPPH free radical scavenging test was did to evaluate the antioxidant potentials of FeCl3, S. chloroleuca, and FeNPs. DPPH test indicated similar antioxidant activities for S. chloroleuca, FeNPs, and butylated hydroxytoluene. In current experiment, we concluded that iron nanoparticles biosynthesized by S. chloroleuca leaf aqueous extract suppressed methadone-induced cell death in a dose-dependent manner in PC12 cells. 相似文献
134.
Hannaford Blake Krischer Christof C. Stark Lawrence 《IEEE transactions on bio-medical engineering》1985,(1):86-89
A portable personal computer has been programmed as a flexible and economical text display device capable of delivering single and multiple words or symbols flashed in the center of the screen with a wide range of repetition times and duty cycles (fraction of stimulus on/off time). All aspects of a computer-controlled experiment are controlled by a command file which can be created by workers with basic word processing skills and no knowledge of computer programming. Digital output is provided for recording stimulus timing on a chart recorder or computer for comparison to eye movements or other externally recorded variables. The system is ideal for zero-eye-movement reading experiments in which sentences are flashed a word or group of words at a time in the center of a CRT screen. If the subject is then asked to repeat the sentence aloud, the percentage of words correctly recalled is a measure of "reading comprehension." Results with nine subjects match previous data [1] obtained cinematographically. 相似文献
135.
The adsorption of HNO3/H2O mixtures on Ag(110) was investigated to learn more about the chemistry of the metal/electrolyte interface. The experiments were performed in ultrahigh vacuum (UHV) using thermal desorption spectroscopy (TDS), low energy electron diffraction (LEED), and electron stimulated desorption ion angular distribution (ESDIAD) over temperatures of 80–650 K and coverages of 0–10 monolayers (ML). As this is the first known study of HNO3 in UHV, the mass spectrometer cracking pattern for HNO3 is here reported. HNO3 adsorbs irreversibly on the clean surface at 80 K and loses its acidic proton to form an adsorbed surface nitrate (NO3) below 150 K. The saturation amount of adsorbed NO3 is 0.4 ± 0.1 ML for which adsorption occurs in either a normal or split c(2 × 2) structure. N03 is stable on the surface up to 450 K beyond which it decomposes directly to gaseous NO2 and NO and adsorbed atomic oxygen. NO3 decomposition is first order with an activation energy Ea = 151±4 kJ mol−1 and a pre-exponential factor of A = 1015.4±0.4s−1. NO3 stabilizes adsorbed H2O by about 8 kJ mol−1 and is hydrated by as many as three H2O molecules. Multilayers of HNO3/H2O desorb at 150–220 K and show evidence of extensive hydrogen bonding and hydration interactions. No evidence for HNO3-induced corrosion or other surface damage was detected in any of these experiments. 相似文献
136.
Roman N. Tolchenov Sergei V. Shirin Nikolai F. Zobov Oleg L. Polyansky Ahilleas N. Maurellis 《Journal of Molecular Spectroscopy》2003,221(1):99-105
A total of 7923 transitions previously derived from long pathlength, Fourier transform spectra of pure water vapor (Schermaul et al., J. Mol. Spectrosc. 211 (2002) 169) have been refitted and reanalyzed using a newly calculated variational linelist. Of these, 6600 lines are weaker than 1 × 10−24 cm/molecule, for which reliable intensities are obtained. These weak lines include 1082 lines, largely due to H216O, which have not been previously observed. A total of 7156 lines were assigned resulting in 329 new energy levels for H216O spread over 32 vibrational levels. Estimates are also given for the band origins of the (022), (140), and (051) vibrational states. 相似文献
137.
The performance of a frequency-hop spread-spectrum system employing carrier jitter against one-dimensional tone jamming (n=1 band multitone jamming) is investigated. First, noncoherent BFSK signaling under continuous-wave (CW) tone interference with arbitrary frequency offset is analyzed. A closed-form expression is derived for the error probability when there is one interfering CW tone and the background noise is negligible. When the background noise is significant, an expression involving one numerical integration is derived for the probability of error. It is shown that an interfering CW tone with power less than that of the signal can still cause errors with significant probability for certain ranges of carrier offsets. Next, the authors apply these results in analyzing the performance of a FHSS communications system under one-dimensional tone jamming when the communicator pseudorandomly jitters his carrier frequency from hop to hop. Two different methods of carrier jittering are considered. It is found that one of the schemes offers approximately a 3 dB gain in signal-to-noise ratio over a system without carrier jittering while the other scheme offers no significant gain 相似文献
138.
139.
Duane C. Hrncir Laura M. Barden Mark R. Wells Peter C. Stark 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(3):233-236
Tetrabutylammonium salts of the mixed haloindates, [Bu4N][InCl3X], X=Cl, Br, I, interact with aromatic solvents forming liquid inclusion compounds. The aromatic/cation ratio (A/C), a measure of the amount of guest aromatic, has been determined for a variety of simple aromatics. The values range from 2.6 to 0.4, substantially lower than the A/A of similar [Bu4N][Al2R6X] liquid clathrates. The ability of these liquid clathrates to function as catalysis media has been explored. The solubility of (Ph3P)2Rh(CO)Cl and (Ph3P)3RhCl in the various clathrates was determined. It was found that significant leaching of the catalyst into the bulk aromatic solvent occurred, ranging from 13 to 94%. A related liquid clathrate, [Li·12-crown-4][InCl4]·(C6H5CH3)2, had <1% of the dissolved catalyst leached. 相似文献
140.
The performance of optimal codes on frequency-hopped channels with partial-band interference is investigated. The performance measures considered are channel capacity and cutoff rate. Worst-case partial-band Gaussian noise interference is assumed with the interference independent of the transmitted signal. The capacity and cutoff rate are calculated as a function of the signal-to-noise ratio. We consider soft decision receivers and hard decision receivers with and without side information. Optimal code rates are found for each of the above cases. The required signal-to-noise ratio for reliable communication when codes are used is determined as a function of the code rate. 相似文献