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排序方式: 共有137条查询结果,搜索用时 15 毫秒
1.
To model effectively the output waveform and propagation delay of a CMOS gate, knowledge of the time point at which it starts to conduct is essential. An efficient method for calculating analytically this time point taking into account the structure of the gate and the input waveform, is introduced. Such a method can easily be integrated into a timing analysis system 相似文献
2.
Video shot detection and condensed representation. a review 总被引:4,自引:0,他引:4
There is an urgent need to develop techniques that organize video data into more compact forms or extract semantically meaningful information. Such operations can serve as a first step for a number of different data access tasks such as browsing, retrieval, genre classification, and event detection. In this paper, we focus not on the high-level video analysis task themselves but on the common basic techniques that have been developed to facilitate them. These basic tasks are shot boundary detection and condensed video representation 相似文献
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4.
In this paper we consider the potential of using an aggressive form of energy conservation for mobile computing environments. The estimators for the round-trip time and round-trip time variance used by TCP are used to direct the transceiver of a mobile node to idle over extended periods of time when packet activity is not anticipated. In addition, we consider data link layer extensions that provide additional control information allowing the mobile to be further selective as to when to idle and when to activate the network interface device. Simulations are conducted to examine the performance of the proposed scheme under various levels of congestion in the fixed part of the network, from completely unloaded to fully congested. The simulations reveal that the technique is promising but its effectiveness depends crucially on the control of the maximum window size used by TCP and on accurate knowledge of the congestion conditions in the network. 相似文献
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6.
Symeon Nikitidis Anastasios Tefas Nikos Nikolaidis Ioannis Pitas 《Pattern recognition》2012,45(12):4080-4091
Nonnegative Matrix Factorization (NMF) is among the most popular subspace methods, widely used in a variety of image processing problems. Recently, a discriminant NMF method that incorporates Linear Discriminant Analysis inspired criteria has been proposed, which achieves an efficient decomposition of the provided data to its discriminant parts, thus enhancing classification performance. However, this approach possesses certain limitations, since it assumes that the underlying data distribution is unimodal, which is often unrealistic. To remedy this limitation, we regard that data inside each class have a multimodal distribution, thus forming clusters and use criteria inspired by Clustering based Discriminant Analysis. The proposed method incorporates appropriate discriminant constraints in the NMF decomposition cost function in order to address the problem of finding discriminant projections that enhance class separability in the reduced dimensional projection space, while taking into account subclass information. The developed algorithm has been applied for both facial expression and face recognition on three popular databases. Experimental results verified that it successfully identified discriminant facial parts, thus enhancing recognition performance. 相似文献
7.
Alexandros Iosifidis Anastasios Tefas Nikolaos Nikolaidis Ioannis Pitas 《Computer Vision and Image Understanding》2012,116(3):347-360
In this paper, a novel multi-view human movement recognition method is presented. A novel representation of multi-view human movement videos is proposed that is based on learning basic multi-view human movement primitives, called multi-view dynemes. The movement video is represented in a new feature space (called dyneme space) using these multi-view dynemes, thus producing a time invariant multi-view movement representation. Fuzzy distances from the multi-view dynemes are used to represent the human body postures in the dyneme space. Three variants of Linear Discriminant Analysis (LDA) are evaluated to achieve a discriminant movement representation in a low dimensionality space. The view identification problem is solved either by using a circular block shift procedure followed by the evaluation of the minimum Euclidean distance from any dyneme, or by exploiting the circular shift invariance property of the Discrete Fourier Transform (DFT). The discriminant movement representation combined with camera viewpoint identification and a nearest centroid classification step leads to a high human movement classification accuracy. 相似文献
8.
Domenico Grasso Michael A. Butkus Dennis O'Sullivan Nikolaos P. Nikolaidis 《Water research》1997,31(12):3045-3056
Soils located near high traffic roadways, particularly where renovations have taken place, typically exhibit elevated levels of trace metals in the upper soil horizon. Regulators are currently seeking an efficient method of site characterization and treatment system design which will lend itself to timely and environmentally efficacious clean-up. The soil investigated in this study was a silty sand collected near a bridge abutment for a major interstate highway. The soil had a total lead content of 1392 mg/kg. In addition, the soil contained a considerable fraction of organic carbon (approximately 6.3%). A sequential chemical extraction indicated that a fraction of contaminants were in labile soil phases and thus amenable to chemical extraction (soil-washing). A soil washing design methodology is presented based on surface chemistry and equilibrium stage operation. In this work, a double layer surface complexation model was used to describe equilibrium sorption behavior and a preliminary design of an ex-situ counter-current equilibrium stage extraction process is presented. Model calibration was conducted using sorption data obtained from a 1:40 solid to liquid ratio (s/l), adsorption edge. Model validation was accomplished with batch titration data and a 1:20 s/l, adsorption edge. The model accurately predicted leachable lead concentrations over a wide pH range. The required number of ideal equilibrium stages was highly sensitive to pH. 相似文献
9.
Spiridon Nikolaidis Theodoros Nikolaidis 《International Journal of Circuit Theory and Applications》2007,35(1):1-15
Pass transistor logic has become important for the design of low‐power high‐performance digital circuits due to the smaller node capacitances and reduced transistors count it offers. However, the acceptance and application of this logic depends on the availability of supporting automation tools, e.g. timing simulators, that can accurately analyse the performance of large circuits at a speed, significantly faster than that of SPICE based tools. In this paper, a simple and robust modelling technique for the basic pass transistor structure is presented, which offers the possibility of fast timing analysis for circuits that employ pass transistors as controlled switches. The proposed methodology takes advantage of the physical mechanisms in the pass transistor operation. The obtained accuracy compared to SPICE simulation results is sufficient for a wide range of input and circuit parameters. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
10.
Aggregation convergecast scheduling in wireless sensor networks 总被引:3,自引:0,他引:3
We consider the problem of scheduling in wireless sensor networks for the purposes of aggregation convergecast. We observe that existing schemes adopt essentially a two phase approach, consisting of, first, a tree construction and,
second, a scheduling phase. Following a similar approach, we propose two new improvements, one to each of the two phases.
Starting with a new lower bound on the schedule length, we make use of it in the tree construction phase. The tree construction
phase consists of solutions to instances of bipartite graph semi-matchings. The scheduling phase is a weight-based priority
scheme that obeys dependency (tree) and interference constraints. Our extensive experiments show that, overall, our proposed
solution not only outperforms all previously proposed solutions in terms of schedule length, but it also significantly extends
the network’s lifetime. 相似文献