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21.
22.
A two-step procedure for restoring scintigraphic images is described. The first step uses a local-statistics algorithm for improvement in signal-to-noise ratio by smoothing the Poisson noise. The second step aims at improvement in spatial resolution by removing the linear blur using the iterative restoration algorithm. We present some results of computer simulations and restoration of scintigraphic images that demonstrate the effectiveness of the proposed procedure. 相似文献
23.
Catalytic dehydrogenative coupling of methane on active carbon. Effect of metal supported on active carbon 总被引:3,自引:0,他引:3
Ethane, ethene, ethyne and hydrogen are obtained in good yields via dehydrogenative coupling of methane in the presence of active carbon as a catalyst. The product yield is increased by supporting metal on active carbon. 相似文献
24.
Selective gas transport in miscible PPO-PS blends 总被引:1,自引:0,他引:1
The permeation rates of He, CO2 and CH4 though miscible blends of polystyrene and poly(phenylene oxide) at 35°C are reported as a function of pressure. Sorption isotherms for CO2 and CH4 are also presented. By using ratios of the permeabilities of the pure gases the separation factors for the gas pairs He---CH4 and CO2---CH4 can be estimated. For both pairs the estimated separation factor goes through a prominent maximum, thus indicating that these blends are more permselective than expected from the behaviour of polystyrene and poly(phenylene oxide). This stems from mobility considerations rather than solubility effects and a qualitative free volume argument is proposed as an explanation. The sorption and transport data have been interpreted and correlated using the dual sorption-mobility models developed previously for glassy polymers. Since the commercial polystyrene used contained a small amount of mineral oil to improve flow behaviour, the effect of this additive on polystyrene properties was explored in some detail. 相似文献
25.
Hirosuke Oku Jyutaro Shudo Kunio Mimura Akinori Haratake Junichi Nagata Isao Chinen 《Lipids》1995,30(2):169-172
A neutral lipid class was isolated by thin-layer chromatography from the skin surface lipids of the hairless mouse. The fraction
migrated faster than triglycerides and had a migration rate similar to that of diacyl alkanediols (diester wax). Upon deacylation,
however, the long-chain diols were identified as 1-alkylglycerol ethers based on their chromatographic properties and on the
mass spectra of their nicotinylidene derivatives. Thus, the skin lipid fraction was identified as 1-O-alkyl-diacylglycerol. The alkyl moieties were all saturated and even-numbered and ranged in chainlength from C16 to C22 with 1-O-hexadecylglycerol amounting to 34% of the total glycerol ether moieties. The fatty acids derived from this lipid fraction
were mostly monoenoic with chainlengths ranging from C16 to C24. The major acyl component was eicosenoic acid (20∶1) representing 61% of the total fatty acids. 相似文献
26.
Yoshinobu Fujishiro Motoyuki Miyata Masanobu Awano Kunihiro Maeda 《Journal of the American Ceramic Society》2003,86(12):2063-2066
The thermal conductivity of polycrystalline Al-doped ZnO was controlled through the fabrication of nanostructured polycrystalline materials, by hot-pressing nanosized Zn1– x Al x O ( x = 0.01, 0.02) particles, which were synthesized by a coprecipitation and spray-drying method. This process resulted in an improved thermoelectric power factor because of the nanosized Zn0.99 Al0.01 O particles of the polycrystalline products. The thermal conductivity also was decreased as a result of the formation of nanocrystalline Zn0.99 Al0.01 O. 相似文献
27.
Naoto Kimbara Akio Nishijima Toshio Sato Yuji Yoshimura Hiromichi Shimada Nobuyuki Matsubayashi Akinori Yukimura 《Catalysis Letters》1990,6(3-6):409-415
TiN supported molybdenum sulfide catalysts showed much higher activity for cleavage of C-C bonds than oxide supported molybdenum sulfide catalysts, indicating the possibility of a new generation of supports for hydroprocessing catalysts. 相似文献
28.
Introduction
Multiply-accumulate operation is the most fundamental operation in digital signal processing for image processing, robotics and automatic control. In this paper, a novel architecture of dynamically reconfigurable fused multiply-adder (FMA) is proposed.Methods
Dynamic reconfiguration is a method that can change the circuit configuration without stop of operation. The proposed circuit provides the following four calculation modes by dynamic reconfiguration: (1) complex number FMA mode, (2) real number FMA mode, (3) complex number parallel calculation mode, and (4) real number parallel calculation mode. The data format is single precision floating point format based on IEEE754. The proposed circuit was designed using Verilog-HDL. It was simulated by logic circuit simulator, and implemented on FPGA.Result
As a result of circuit synthesis, we confirmed the reduction of resource in the proposed circuit. Furthermore, we confirmed proper result for each calculation mode by logic simulation and experiment on FPGA.Conclusion
The proposed circuit provides the four calculation modes by dynamic reconfiguration. We confirmed the reduction of resource and proper result for each calculation mode. 相似文献29.
Blending a crosslinked high‐density polyethylene (xHDPE) enhances melt strength and strain hardening behavior in elongational viscosity of high‐density polyethylene (HDPE) to a great degree. Gel fraction of xHDPE has a stronger effect on the strain hardening than sol fraction, although sol fraction also enhances the strain hardening to some degree. Further, the xHDPE crosslinked by peroxide in a compression mold exhibits more pronounced effect than xHDPE by radiation, which is attributed to the difference in the amount of the gel fraction. The xHDPE, which enhances the strain hardening, has sparse crosslink points in the network. Moreover, it was found from linear viscoelastic measurements, such as oscillatory modulus and relaxation modulus, that the xHDPE is characterized as a critical gel, which was also supported by the result of tensile testing. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 73–78, 2002 相似文献
30.
Generally, sorption isotherms for gases like CO2 in glassy polymers are concave to the pressure axis, whereas in the rubbery state these isotherms are linear for gases or sometimes convex to the pressure axis for more condensable vapors. Examples of CO2 isotherms are reported here that show at low pressure the curvature characteristic of glasses and then become linear at higher pressures. This is observed when the glass transition temperature Tg is not much greater than the observation temperature T, and plasticization of the polymer by sorbed CO2 causes Tg to become equal to T within the range of pressures employed in the isotherm measurement. For the sorption of vapors in glassy polymers, this can lead to sigmoidal isotherms, as discussed using an illustration from the literature. 相似文献