共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
《Microwave Theory and Techniques》1982,30(6):915-917
This paper presents a time domain analysis of a microwave 10-GHz FET oscillator, which employs a practical and efficient computer model for the FET. Good agreement is demonstrated between the predicted and measured performance. A sensitivity analysis of the circuit is performed with respect to some of the FET parameters. This is useful information to estimate variation in production. 相似文献
3.
We develop a polymeric waveguide optical switch with a bascule structure. Our novel matrix switch diverts light from one waveguide to a crossing waveguide in a polymeric waveguide film, using total internal reflection (TIR) of the interface between a waveguide and a trench at the waveguide cross point by mechanical actuation. The key technique for achieving a low-loss property is a novel cleaving method of forming trenches at waveguide cross points. We achieved a loss of 5 dB for the longest path of an 8 times 8 matrix switch demonstrator, high speed switching operation up to 100 mus, and reliable performance over 10 million times switching. 相似文献
4.
5.
A Novel Adaptive Approach to Process Binary Fingerprint Images Using Directional Morphological Operations 下载免费PDF全文
Jin Qi 《电子科技学刊:英文版》2009,7(2):129-131
An adaptive algorithm for removing false ridges, bridges and filling gaps in binary fingerprint images based on morphological operations is presented. A novel procedure for structuring elements design based on the specific fingerprint characteristic is described. Using the images from FVC2000 database, we have compared our method proposed here with the approach proposed by other ones. The Experimental results have demonstrated the efficiency of our method. 相似文献
6.
An adaptive algorithm for removing false ridges, bridges and filling gaps in binary fingerprint images based on morphological operations is presented. A novel procedure for structuring elements design based on the specific fingerprint characteristic is described. Using the images from FVC2000 database, we have compared our method proposed here with the approach proposed by other ones. The Experimental results have demonstrated the efficiency of our method. 相似文献
7.
《Industrial Electronics, IEEE Transactions on》2008,55(9):3374-3380
8.
与HBT工艺兼容的新型负阻器件的研制与分析 总被引:1,自引:1,他引:0
在HBT工艺基础上,通过对器件结构的特殊设计,研制出了一类新型三端负阻器件,其恒压控制型负阻的PVCR大于800,并伴有恒流控制型负阻。通过atlas器件模拟软件进行模拟后对其物理机制进行了解释。该器件既能保持HBT高频、高速的特点,又具有负阻、双稳、自锁等特性,同时与普通台面HBT工艺兼容,易于集成,是一种具有研究和应用价值的新型负阻器件。 相似文献
9.
10.
Ahmed Abdul Salam Ray Sheriff Saleh Al‐Araji Kahtan Mezher Qassim Nasir 《ETRI Journal》2017,39(5):718-728
Empirical modeling of wireless fading channels using common schemes such as autoregression and the finite state Markov chain (FSMC) is investigated. The conceptual background of both channel structures and the establishment of their mutual dependence in a confined manner are presented. The novel contribution lies in the proposal of a new approach for deriving the state transition probabilities borrowed from economic disciplines, which has not been studied so far with respect to the modeling of FSMC wireless fading channels. The proposed approach is based on equal portioning of the received signal‐to‐noise ratio, realized by using an alternative probability construction that was initially highlighted by Tauchen. The associated statistical procedure shows that a first‐order FSMC with a limited number of channel states can satisfactorily approximate fading. The computational overheads of the proposed technique are analyzed and proven to be less demanding compared to the conventional FSMC approach based on the level crossing rate. Simulations confirm the analytical results and promising performance of the new channel model based on the Tauchen approach without extra complexity costs. 相似文献
11.
The major drawback of incoherent broadband sources (BBSs) is their inherent intensity noise. Semiconductor optical amplifiers (SOAs) can be exploited at the transmitter to mitigate this noise. Optical filtering at the receiver, however, leads to the return of most of suppressed noise. Wider filtering at the receiver is the best known strategy to maintain performance gains, at the price of reduced spectral efficiency due to the tradeoff between noise cleaning and adjacent channel crosstalk. We introduce a novel balanced receiver for wavelength division multiplexing (WDM) systems that maintains greater noise cleaning and leaves spectral efficiency unchanged. Unlike standard receivers, our balanced scheme does not filter the desired signal. In this paper, we first demonstrate that the newly proposed receiver is equivalent to standard WDM receivers when no SOA for noise cleaning is present at the transmitter. Although a 2.9-dB power penalty is incurred, network capacity is unchanged, i.e., bit error rate (BER) floors due to intensity noise are the same. When SOAs are employed to mitigate severe intensity noise, we show that our receiver outperforms the wide filtering strategy by two orders of magnitude. Dense WDM capacity is demonstrated up to 10 Gb/s using a thermal source, a saturated SOA, and the balanced detection scheme. A BER of 10-6 is achieved at 10 Gb/s; further improvement is possible using low overhead forward error correction or a better SOA design. This demonstrates the ability of spectrum-sliced wavelength division multiplexing (SS-WDM) passive optical networks (PONs) to operate at 10 Gb/s at good spectral efficiency. Error performance better than 10-9 is achieved up to 8 Gb/s with 30-GHz optical channel bandwidth and 100-GHz spacing. 相似文献
12.
《Electron Device Letters, IEEE》2007,28(5):379-382
13.
14.
Junwon Lee Jaeik Cho Jungtaek Seo Taeshik Shon Dongho Won 《Mobile Networks and Applications》2013,18(1):122-128
Recent developments have caused the expansion of various cloud computing environments and services. Cloud computing environments have led to research in the areas of data processing, virtual environments, and access control. Information security is the most important research area for these environments security. In this study, we analyzed typical example of network testbeds, which have been used for malicious activity data collection and its subsequent analysis. Further, we propose an effective malicious network application testbed, which is based on a cloud system. We also verified the performance of our new testbed by comparing real malicious activity with the cloud-based testbed results. 相似文献
15.
This work describes a distributed fault restoration algorithm, called the Dynamic Multiple Ring Algorithm (DMRA), for application in WDM mesh networks. This study explores the choice of restoration paths and the assignment of fault-tolerant bandwidth when a link, node, or channel failure occurs according to the change in traffic load, number of nodes, and transmission delay including propagation and switching delays. Accordingly, the primary aim of this work is to use networking segments near faults to share the restoration load throughout a mesh network. Each node searches for restoration paths in their near environment using the proposed DMRA. Nodes use distributed control to search for neighboring nodes and to establish the relationship between them to build numerous logical rings. Nodes can also locate faults in the logical rings. These rings establish the restoration paths. The traffic load over failed links or nodes can be diverted to other paths in the networking segments. The cost of the restoration paths is computed at each node based on both the current capacity and the transmission delay. The selected restoration paths are suitable transmission routes in the network neighborhood. Hence, restoration paths can be identified and wavelength assigned quickly according to network bandwidth and traffic load. Simulation results reveal that the proposed method works extremely quickly and has a high success rate. Consequently, it is very useful for applications in real WDM networks, where the status varies from minute to minute.Corresponding author is presently a guest scientist with the National Institute of Standards and Technology, USA. This research was partially supported by the Grant of National Science Council, ROC (NSC-92-2218-E-155-004 and NSC-93-2917-I-155-001). 相似文献
16.
An efficient and yet simple neural-based approach is utilized to design real finite-impulse response filters with arbitrary complex frequency responses in the least-squares sense. The proposed approach establishes the quadratic error difference of the filter optimization in the frequency domain as the Lyapunov energy function. Consequently, the optimal filter coefficients are obtained with good performance and fast convergence speed. To achieve good convergences for large filter lengths, a cooling process of simulated annealing is used for the neural activation function. Several examples and comparisons to the existing methods are presented to illustrate the effectiveness and flexibility of the neural-based method 相似文献
17.
Pareto-Efficient and Goal-Driven Power Control in Wireless Networks: A Game-Theoretic Approach With a Novel Pricing Scheme 总被引:1,自引:0,他引:1
A Pareto-efficient, goal-driven, and distributed power control scheme for wireless networks is presented. We use a noncooperative game-theoretic approach to propose a novel pricing scheme that is linearly proportional to the signal-to-interference ratio (SIR) and analytically show that with a proper choice of prices (proportionality constants), the outcome of the noncooperative power control game is a unique and Pareto-efficient Nash equilibrium (NE). This can be utilized for constrained-power control to satisfy specific goals (such as fairness, aggregate throughput optimization, or trading off between these two goals). For each one of the above goals, the dynamic price for each user is also analytically obtained. In a centralized (base station) price setting, users should inform the base station of their path gains and their maximum transmit-powers. In a distributed price setting, for each goal, an algorithm for users to update their transmit-powers is also presented that converges to a unique fixed-point in which the corresponding goal is satisfied. Simulation results confirm our analytical developments. 相似文献
18.
Yu-Ting Hsueh Zhensheng Jia Hung-Chang Chien Jianjun Yu Gee-Kung Chang 《Photonics Technology Letters, IEEE》2009,21(18):1338-1340
We experimentally demonstrated a novel radio-over-fiber system to simultaneously generate dispersion-tolerant multiband downstream signals, including millimeter-wave, microwave, and baseband signals, based on multicarrier modulation in an intensity modulator and a subsequent optical filter. The uplink connection is realized by remodulation of downlink optical carrier and by baseband detection in the central office. The high-dispersion tolerance comes from the subcarrier cross-selection with only one data-bearing tone before signal beating in the receiver. The power penalty of 1.4 dB for 60-GHz carrier and negligible degradation for baseband and upstream are achieved for 2.5-Gb/s signal after 50-km single-mode fiber (SMF-28) and 4-m air link transmission. The theoretical analysis is also provided to obtain the optimal operation point. 相似文献
19.
20.
Hao Chi Xihua Zou Jianping Yao 《Lightwave Technology, Journal of》2009,27(5):511-521
Recently, optical phase modulation has been widely used in microwave photonics (MWP) systems, such as radio over fiber systems, photonic microwave filters, optical microwave and millimeter-wave signal generators, and optical subcarrier frequency up-converters. An optical phase-modulated signal can be converted to an intensity-modulated signal in a dispersive optical fiber. Due to the intrinsic nonlinearity of optical phase modulation, for linear applications such as microwave signal distribution and filtering, the modulation index should be kept small to minimize the unwanted modulation nonlinearity. However, for nonlinear applications such as microwave frequency multiplication and subcarrier frequency upconversion, the modulation index should be large to maximize the frequency multiplication and upconversion efficiency. In this paper, for the first time to our knowledge, we develop a thorough theoretical framework for the characterization of phase-modulation-based MWP systems, in which the phase modulation to intensity modulation conversion is realized using a dispersive fiber. Analytical models for the distributions of single-tone and two-tone microwave signals and for microwave frequency multiplication and subcarrier frequency upconversion are developed, which are verified by numerical simulations. The analytical models for single-tone and two-tone transmissions are further confirmed by experiments. The developed analytical models provide an accurate mathematical tool in designing phase-modulation-based MWP systems. 相似文献