全文获取类型
收费全文 | 63篇 |
免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 7篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
能源动力 | 7篇 |
轻工业 | 4篇 |
石油天然气 | 1篇 |
无线电 | 9篇 |
一般工业技术 | 6篇 |
冶金工业 | 5篇 |
原子能技术 | 1篇 |
自动化技术 | 18篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有64条查询结果,搜索用时 15 毫秒
11.
R. Boulahia J.M. Gloaguen F. Zaïri M. Naït-Abdelaziz R. Seguela T. Boukharouba J.M. Lefebvre 《Polymer》2009,50(23):5508-5517
Severe plastic deformation by equal channel angular extrusion (ECAE) is an ingenious deformation process used to modify texture and microstructure without reducing sample cross-section. The application of single ECAE pass to polypropylene (PP) was meticulously investigated at room temperature using a 90° die-angle tooling. The ECAE-induced deformation behaviour was examined in relation to the load versus ram-displacement curves. Depending on extrusion conditions, PP displayed various types of plastic flow. For ram velocities beyond 4.5 mm/min, severe shear bands consisting of successive translucent and opaque bands were observed, accompanied on the top surface by more or less pronounced periodic waves. Although the application of a back-pressure significantly reduced the wave and shear-banding phenomena, slightly inhomogeneous shear deformation was still observed. Shear bands were only suppressed by decreasing extrusion velocity. The strain-induced crystalline microstructure was investigated by X-ray scattering. Shear-banded samples exhibited a strong texturing of the (hk0) planes along the shear direction in the translucent bands whereas perfect crystalline isotropy appeared in the opaque bands. Application of back-pressure and/or reducing ram velocity resulted in uniform texturing along the extruded sample. Yet, texturing changed from single shear to twin-like shear orientation about the shear direction. Mechanical properties changes of the extruded samples due to back-pressure and extrusion velocity effects were analyzed via uniaxial tensile tests. The tensile samples displayed multiple strain localizations in shear-banded materials whereas quite homogeneous deformation appeared for non-banded ones. These effects were connected with the crystalline texturing. The results also revealed significant increase in the strain hardening after ECAE. Digital image correlation technique suitable for large deformation was used for determining the full-field strain of the tensile samples in relation to tensile strain and ECAE conditions. 相似文献
12.
Multimedia Tools and Applications - In modern life, the massive number of vehicles makes it hard for a human being to process its related information. So, it is important to build an automatic... 相似文献
13.
This paper is focusing on the numerical simulation of a swirling flame, resulting from the interaction of multiple fires, evolving in a free and unlimited environment. A typical system, formed by a central fire source surrounded by four heat sources, is used. Since the thermal characteristic of the surrounding sources is the main engine for the rotation of flame, a detailed study is performed by varying the heating flux of these sources. This study shows that an increase of the heating flux of surrounding sources has as a result an intensification of the penetrating air puffs through the openings between the surrounding four heat sources. These puffs tangentially drive the central flame, thus producing a marked improvement on the angular momentum. Moreover, this study shows that the flame height is strongly affected by the flame rotation. Moreover, two different aspects of the flame height evolution are observed from the flow visualization and the thermal and dynamic fields for the different cases studied. 相似文献
14.
Anoire Ben Jdidia Alain Bellacicco Taissir Hentati Maher Barkallah Mohamed Taoufik Khabou Alain Rivier 《中国工程学刊》2019,42(5):377-384
The accurate evaluation of electrical energy demanded by a CNC toolpath during a machining process is essential to determine its efficiency. Actually, the dynamic behavior of cutting forces seems to be neglected by investigators despite its influence on the consumed cutting energy during a face milling operation. This paper aims to investigate the effect of dynamic behavior of the machining system in order to take into account the dynamic response of the cutting forces on the axis feed power prediction. A dynamic cutting power model is developed in order to predict the consumed cutting energy. A parametric study is performed in order to show the impact of cutting conditions on the consumed energy values. The numerical results are compared to experimental ones. 相似文献
15.
Taoufik Saidani Mohamed Atri Lazhar Khriji Rached Tourki 《Journal of Real-Time Image Processing》2016,11(1):63-74
With the augmentation in multimedia technology, demand for high-speed real-time image compression systems has also increased. JPEG 2000 still image compression standard is developed to accommodate such application requirements. Embedded block coding with optimal truncation (EBCOT) is an essential and computationally very demanding part of the compression process of JPEG 2000 image compression standard. Various applications, such as satellite imagery, medical imaging, digital cinema, and others, require high speed and performance EBCOT architecture. In JPEG 2000 standard, the context formation block of EBCOT tier-1 contains high complexity computation and also becomes the bottleneck in this system. In this paper, we propose a fast and efficient VLSI hardware architecture design of context formation for EBCOT tier-1. A high-speed parallel bit-plane coding (BPC) hardware architecture for the EBCOT module in JPEG 2000 is proposed and implemented. Experimental results show that our design outperforms well-known techniques with respect to the processing time. It can reach 70 % reduction when compared to bit plane sequential processing. 相似文献
16.
Mostafa Taoufik Erwan Le Roux Jean Thivolle-Cazat Christophe Copéret Jean-Marie Basset Barry Maunders Glenn J. Sunley 《Topics in Catalysis》2006,40(1-4):65-70
Silica and alumina supported tantalum and tungsten hydrides were tested in alkane metathesis, for comparison of their catalytic
properties. In propane metathesis [W]–H/Al2O3 proves to be twice more efficient than the usual [Ta]–H/SiO2 catalyst which is still better than [Ta]–H/Al2O3 and [W]–H/SiO2. Tungsten based catalysts lead to a narrower distribution in the products selectivity and to a higher amount of linear products
than [Ta]–H/SiO2. [W]–H/Al2O3 is also a better catalyst than [Ta]–H/SiO2 for butane metathesis but is less efficient with ethane. Whereas the results in the case of propane or butane can involve
the higher initial activity and a lower deactivation of the tungsten catalyst, in the case of ethane, mechanistic or kinetic
aspects can be envisaged in particular concerning the difficulty to dehydrogenate ethane into ethylene. 相似文献
17.
Lassâad Walha Yassine DrissMohamed Taoufik Khabou Tahar FakhfakhMohamed Haddar 《Mechanism and Machine Theory》2011,46(7):986-997
This paper investigates the nonlinear dynamic behavior of an automotive clutch coupled with a helical two stage gear system. The nonlinear dynamic model is simulated by twenty seven degrees of freedom and including three types of nonlinearity: dry friction path, double stage stiffness and spline clearance. The utility of the proposed nonlinear model is illustrated by the industrial need to clearly identify the dynamic behavior of mechanical elements (shafts, bearings, gears, flywheel, pressure plate, hub of the clutch…) and reduce vibration. The governing nonlinear time varying motion equation formulated is resolved by the analytic Runge Kutta method.Then the modeling of the eccentricity defect located on the gear and the flywheel of the clutch is done. The effect of this defect on the nonlinear dynamic behavior of the system is investigated. 相似文献
18.
Taoufik Bouezmarni Jeroen V.K. Rombouts 《Computational statistics & data analysis》2010,54(2):245-261
The Gaussian kernel density estimator is known to have substantial problems for bounded random variables with high density at the boundaries. For independent and identically distributed data, several solutions have been put forward to solve this boundary problem. In this paper, we propose the gamma kernel estimator as a density estimator for positive time series data from a stationary α-mixing process. We derive the mean (integrated) squared error and asymptotic normality. In a Monte Carlo simulation, we generate data from an autoregressive conditional duration model and a stochastic volatility model. We study the local and global behavior of the estimator and we find that the gamma kernel estimator outperforms the local linear density estimator and the Gaussian kernel estimator based on log-transformed data. We also illustrate the good performance of the h-block cross-validation method as a bandwidth selection procedure. An application to data from financial transaction durations and realized volatility is provided. 相似文献
19.
A. Mesbah F. Zaïri S. Boutaleb J. M. Gloaguen M. Naït‐Abdelaziz S. Xie T. Boukharouba J. M. Lefebvre 《应用聚合物科学杂志》2009,114(5):3274-3291
To provide a better understanding of the relationship between nanostructure and overall material stiffness in the case of polymer/clay nanocomposites, both analytical and finite element modeling were considered. A micromechanical analytical approach based on a multiscale framework is presented in which special attention is devoted to the constrained region around reinforcements. The thickness of the constrained region is seen as a characteristic length scale and the effect of particle size is explicitly introduced in the model. Moreover, the constrained region presents graded properties. The hierarchical morphology of intercalated silicate stacks is also explicitly introduced in the micromechanical model from an equivalent stiffness method in which the silicate stacks are replaced by homogeneous particles with constructed equivalent anisotropic stiffness. The orientational averaging process is used to derive the overall stiffness tensor of nanocomposite materials containing randomly oriented reinforcements. The respective influence of volume fraction, aspect ratio, size and orientation of the reinforcements, matrix properties, number of silicate layers per stack, and interlayer spacing on the overall nanocomposite stiffness is analyzed. The overall stiffness of polymer/clay nanocomposite systems is also evaluated by means of finite element simulations and the results compare favorably with model predictions. From an experimental point of view, relevant morphological and mechanical data were obtained on polyamide‐6 nanocomposites prepared using a modified montmorillonite Cloisite 30B and an unmodified sodium montmorillonite Cloisite Na+. The amount of constrained region around reinforcements was estimated using results issued from dynamic mechanical analyses and differential scanning calorimetry. Comparison to the model clearly underlines the contribution of the constrained region to the stiffness improvement. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
20.
Hedi Sakli Hafedh Benzina Taoufik Aguili Jun Wu Tao 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(8):877-883
This paper is an analysis of rectangular waveguide completely full of ferrite magnetized longitudinally. The analysis is based
on the formulation of the transverse operator method (TOM), followed by the application of the Galerkin method. We obtain
an eigenvalue equation system. The propagation constant of some homogenous and anisotropic waveguide structures with ferrite
has been obtained. The results presented here show that the transverse operator formulation is not only an elegant theoretical
form, but also a powerful and efficient analysis method, it is useful to solve a number of the propagation problems in electromagnetic.
One advantage of this method is that it presents a fast convergence. Numerical examples are given for different cases and
compared with the published results. A good agreement is obtained. 相似文献