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11.
Long Term Evolution (LTE) is a promising technology for a high communication quality thanks to its radio link flexibility using Adaptive Modulation and Coding (AMC), Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) technologies. In this paper, we address the adaptive resource allocation problem in down-link transmission of MIMO-OFDMA systems. We aim at maximizing the total system capacity to meet the 4G-technologies promises. In order to reduce the computational complexity, the original optimization problem is divided into sub-optimal ones. Firstly, a recursive Physical Resource Block (PRB) allocation algorithm is developed where the Effective Signal-to-Interference-plus-Noise Ratio (ESINR) metric is investigated to properly characterize the channel condition. Secondly, a power allocation procedure is performed. As all resource blocks allocated to the same user must use the same Modulation and Coding Scheme (MCS) according to the LTE standard requirements, power optimization sub-problem is divided into three steps: power allocation among PRBs, power allocation among antennas and power allocation among users. Finally, a more effective MCS is obtained, which ensures a better system capacity. Simulation results prove the efficiency of the proposed method to maximize the total system capacity with a low complexity even in the case of loaded systems compared to Minimum-MCS (Min-MCS) and Maximum-SINR (Max-SINR) algorithms.  相似文献   
12.
Mass transport of solvents into immiscible blends may exhibit a non-Fickian behavior due to the deformation of the embedded interface that couples with diffusion. We introduce an interface area covariant tensor N as a structural state variable and derive a set of thermodynamically-consistent PDEs and ODEs transport equations for the bulk and time-dependent boundaries. The proposed model, which is a reformulation of that derived by El Afif (2008) and El Afif et al. (2003), improves both mathematically and numerically the investigation of the diffusion-interface coupling and provides reasonable predictions of the sorption-permeation one dimensional treatment affording good agreement with experimental data. The tensor N englobes, into a single morphological quantity, all information regarding diffusion-induced changes in the size and shape anisotropy of the interface area. Predicted results include concentration, components of N , residual stresses, mass-uptake, and swelling. Scaling leads to three relevant dimensionless parameters: a mixing-interface coupling constant and bulk and boundary diffusion Deborah numbers.  相似文献   
13.
Several new siloxane lubricants were synthesized with linear and ring-shaped branch structures of various lengths and branch contents, aiming at a search for better molecular design for lower boundary friction and more effective surface protection against wear of materials. Their molecular structure and mass were measured by means of nuclear magnetic resonance and gel permeation chromatography, respectively. The new lubricants were compared with commercially available polysiloxanes, poly-α-olefins, and perfluoropolyether in lubricating a steel ball-on-steel disk interface using a tribotester at a load of 1.76 GPa and an entrainment speed of 0.025 m/s. The results are used to explain the effects of alkyl branch length L, pendant type J, percent of branch functional monomers Q, and degree of polymerization DP on siloxane design for the most effective boundary lubrication.  相似文献   
14.
Journal of Computational Electronics - Electric-field-controlled charge transport is a crucial concept of modern computers, embodied, namely in field-effect transistors. The metallic gate voltage...  相似文献   
15.
We report a case of primary choriocarcinoma of the cervix in which the patient died 9 months later. The treatment consisted to administer 5 cycles of chemotherapy pre-operatively and a colpohysterectomy. The pathogeny is a cervical migration of trophoblastics cells after a normal or molar pregnancy which degenerate to choriocarcinoma.  相似文献   
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17.
An authentication watermark is a hidden data inserted into an image that can be used to detect any accidental or malicious alteration in the image. Many authentication‐watermarking techniques for continuous‐tone images are described in the literature, but only a quite small number of secure authentication watermarking techniques are available for binary/halftone images. This article proposes a simple solution for inserting a secure authentication watermark in binary/halftone images. It consists of choosing a set of pseudo‐random pixels in the image, clearing them, computing the message authentication code (or the digital signature) of the now‐cleared image, and inserting the resulting code into the selected random pixels. Dispersed‐dot halftone images watermarked by the proposed technique present better visual quality than do watermarked generic binary images. However, in practice, the visual degradation is hardly noticeable in either case. The proposed technique seems to be the only binary/halftone watermarking scheme that can detect even a single pixel alteration in the host image. It can be used with secret‐key or public‐key ciphers. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 147–152, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20018  相似文献   
18.
“Rambak” crackers are one of the traditional foods consumed among Indonesian people made from various kinds of animal skin. The present study highlights the analysis of lard obtained from extraction of “rambak” crackers using Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics of partial least square and principle component analysis. FTIR spectroscopy at wavenumber regions of 1200–1000 cm–1 was successfully used for quantification and classification of lard in “rambak” crackers. The relationship between actual value of lard and Fourier transform infrared predicted value has R2 value of 0.946 with low errors in calibration and validation models. Furthermore, the chemometrics principle component analysis can be successfully used for determination of pig skin through analysis of lard in commercial “rambak” crackers. The developed method (FTIR spectroscopy coupled with chemometrics) is rapid and reliable for quantification and classification of lard in “rambak” crackers.  相似文献   
19.
Garments made from cotton fabrics can readily absorb perspiration during strenuous activities but give poor performance in terms of wicking and evaporation of the perspiration, resulting in wet sticky feeling to the wearer. The aim of this study was to investigate the effect of design and method of creating wicking channels on the moisture management and air permeability of cotton fabrics. The fabric specimens were printed with hydrophobic fluorocarbon finish using four different print designs, each with two different types of printing squeegees. It was found that both the type of print design and squeegee type significantly affect most of the moisture management properties of the fabric. The study concluded that by selecting a suitable print design and squeegee type, moisture management capability of cotton fabrics can be significantly improved without sacrificing the fabric air permeability.  相似文献   
20.
Data are presented from an investigation of the use of monophasic contraceptive pills chosen by different age groups. Analyses are made of the data obtained from the Bulgarian Association for Family Planning (BAFP) card index for the last two years. Information is given on the number of observed cycles, type of applied contraceptive pill, aims of their application (contraception, treatment of acne, menstrual disturbances etc.), age of patients, as well as any possible adverse effects--change in blood pressure, bodyweight changes, intermenstrual bleeding, hairiness, breast problems, paraclinical changes, etc. The observed cycles show a very small percentage of adverse effects with hormonal contraception, mainly during the first 2 or 3 cycles, with predominance of intermenstrual bleeding. No bodyweight changes or increased hairiness were observed.  相似文献   
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