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21.
Pattern Analysis and Applications - Human face is a widely used biometric modality for verification and revealing the identity of a person. In spite of a great deal of research on face recognition,...  相似文献   
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An irreducible Bit Error Rate (BER) exists when IS-54 (the North American standard for digital cellular phones) is transmitted over a mobile flat fading radio channel. Such a BER is due to the motion of the mobile station (and surrounding reflectors) relative to the base station which in turn creates what is known as Random FM. At high vehicle speeds (e.g. 100 Km/hr), the irreducible BER becomes unacceptable (>- 4 × 10–5) for data transmission. The paper shows that it is possible to reduce the effects of Random FM and to achieve acceptable BERs (< 10–5) for data transmission. This is based on using the Hilbert transform to estimate the effects of Random FM and removing it from the IS-54 signal. A theoretical justification is offered which is based on expressing the channel distortion as a product of time domain zeros.Parts of this paper have appeared in: M. Fattouche & H. Zaghloul, Error Reduction of DMPSK transmitted over Fading Channels using the Hilbert transform, in Wireless '93 Proceedings, Calgary, Alberta, July 12–15, 1993.  相似文献   
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Neural Computing and Applications - Intelligent Transportation Systems (ITS) are the most widely used systems for road traffic management. The vehicle type classification (VTC) is a crucial ITS...  相似文献   
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A novel inorganic hollow fiber membrane reactor (iHFMR) has been developed and applied to the catalytic dehydrogenation of propane to propene. Alumina hollow fiber substrates, prepared by a phase inversion/sintering method, possess a unique asymmetric structure that can be characterized by a very porous inner surface from which finger-like voids extend across ∼80% of the fiber cross-section with the remaining 20% consisting of a denser sponge-like outer layer. In contrast to other existing Pd/Ag composite membranes, where an intermediate γ-Al2O3 layer is often used to bridge the Pd/Ag layer and the substrate, the Pd/Ag composite membrane prepared in this study was achieved by coating the Pd/Ag layer directly onto the outer surface of the asymmetric substrate. After depositing submicron-sized Pt (0.5 wt %)/γ-alumina catalysts in the finger-like voids of the substrates, a highly compact multifunctional iHFMR was developed. Propane conversion as high as 42% was achieved at the initial stage of the reaction at 723 K. In addition, the space-time yields of the iHFMR were ∼60 times higher than that of a fixed bed reactor, demonstrating advantages of using iHFMR for dehydrogenation reactions. © 2009 American Institute of Chemical Engineers AIChE J, 2009  相似文献   
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One technology that seems to be promising for automobile pollution reduction is the Homogeneous Charge Compression Ignition (HCCI). This technology still faces auto-ignition and emission-control problems. This paper focuses on the emission problem, since it is incumbent to realize engines that pollute less. For this purpose, this paper presents results concerning the measurement of the emissions of CO, NOx, CO2, O2 and hydrocarbons. HCCI conditions are used, with equivalence ratios between 0.26 and 0.54, inlet temperatures of 70 °C and 120 °C and compression ratios of 10.2 and 13.5, with different fuel types: gasoline, gasoline surrogate, diesel, diesel surrogate and mixtures of n-heptane/toluene. The effect of dilution is considered for gasoline, while the effect of the equivalence ratio is considered for all the fuels. No significant amount of NOx has been measured. It appeared that the CO, O2 and hydrocarbon emissions were reduced by decreasing the toluene content of the fuel and by decreasing the dilution. The opposite holds for CO2. The reduction of the hydrocarbon emission appears to compete with the reduction of the CO2 emission. Diesel seemed to produce less CO and hydrocarbons than gasoline when auto-ignited. An example of emission reduction control is presented in this paper.  相似文献   
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The objective of the present study was to identify advantages and limitations of the application of microdosimetric concepts for inhaled radon progeny activities in the lungs. The methods employed for this analysis were a recently developed Monte-Carlo microdosimetry code for the calculation of energy deposition in bronchial target cells and the Probability Per Unit Track Length (PPUTL) model, which relates these microdosimetric parameters to cellular radiation effects. The major advantages of internal microdosimetry of radon progeny in bronchial airways are: (i) quantitative characterisation of non-uniform dose distributions and identification of target sites with enhanced carcinogenic potential, (ii) quantification of low doses of alpha particles by the number of cells hit and the dose received by those cells, (iii) illustration of the random variations of cellular doses by specific energy distributions and (iv) establishment of a direct link to cellular radiobiological effects. At present, a major limitation of microdosimetry is the extrapolation of the response of individual cells to the resulting tissue response, which is still not fully explored.  相似文献   
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In order to contribute to the solution of controlling the autoignition in a homogeneous charge compression ignition (HCCI) engine, parameters linked to external gas recirculation (EGR) seem to be of particular interest. Experiments performed with EGR present some difficulties in interpreting results using only the diluting and thermal aspect of EGR. Lately, the chemical aspect of EGR is taken more into consideration, because this aspect causes a complex interaction with the dilution and thermal aspects of EGR. This paper studies the influence of EGR on the autoignition process and particularly the chemical aspect of EGR. The diluents present in EGR are simulated by N2 and CO2, with dilution factors going from 0 to 46 vol%. For the chemically active species that could be present in EGR, the species CO, NO, and CH2O are used. The initial concentration in the inlet mixture of CO and NO is varied between 0 and 170 ppm, while that of CH2O alters between 0 and 1400 ppm. For the investigation of the effect of the chemical species on the autoignition, a fixed dilution factor of 23 vol% and a fixed EGR temperature of 70 °C are maintained. The inlet temperature is held at 70 °C, the equivalence ratios between 0.29 and 0.41, and the compression ratio at 10.2. The fuels used for the autoignition are n-heptane and PRF40. It appeared that CO, in the investigated domain, did not influence the ignition delays, while NO had two different effects. At concentrations up until 45 ppm, NO advanced the ignition delays for the PRF40 and at higher concentrations, the ignition delayed. The influence of NO on the autoignition of n-heptane seemed to be insignificant, probably due to the higher burn rate of n-heptane. CH2O seemed to delay the ignition. The results suggested that especially the formation of OH radicals or their consumption by the chemical additives determines how the reactivity of the autoignition changed.  相似文献   
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The alternative HCCI combustion mode presents a possible means for decreasing the pollution with respect to conventional gasoline or diesel engines, while maintaining the efficiency of a diesel engine or even increasing it. This paper investigates the possibility of using gasoline in an HCCI engine and analyzes the autoignition of gasoline in such an engine. The compression ratio that has been used is 13.5, keeping the inlet temperature at 70 °C, varying the equivalence ratio from 0.3 to 0.54, and the EGR (represented by N2) ratio from 0 to 37 vol%. For comparison, a PRF95 and a surrogate containing 11 vol% n-heptane, 59 vol% iso-octane, and 30 vol% toluene are used. A previously validated kinetic surrogate mechanism is used to analyze the experiments and to yield possible explanations to kinetic phenomena. From this work, it seems quite possible to use the high octane-rated gasoline for autoignition purposes, even under lean inlet conditions. Furthermore, it appeared that gasoline and its surrogate, unlike PRF95, show a three-stage autoignition. Since the PRF95 does not contain toluene, it is suggested by the kinetic mechanism that the benzyl radical, issued from toluene, causes this so-defined “obstructed preignition” and delaying thereby the final ignition for gasoline and its surrogate. The results of the kinetic mechanism supporting this explanation are shown in this paper.  相似文献   
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