2013/2

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A Comparison of the Machine Learning Algorithm for Evaporation Duct Estimation
(Společnost pro radioelektronické inženýrství, 2013-06) Yang, Chao
In this research, a comparison of the relevance vector machine (RVM), least square support vector machine (LSSVM) and the radial basis function neural network (RBFNN) for evaporation duct estimation are presented. The parabolic equation model is adopted as the forward propagation model, and which is used to establish the training database between the radar sea clutter power and the evaporation duct height. The comparison of the RVM, LSSVM and RBFNN for evaporation duct estimation are investigated via the experimental and the simulation studies, and the statistical analysis method is employed to analyze the performance of the three machine learning algorithms in the simulation study. The analysis demonstrate that the M profile of RBFNN estimation has a relatively good match to the measured profile for the experimental study; for the simulation study, the LSSVM is the most precise one among the three machine learning algorithms, besides, the performance of RVM is basically identical to the RBFNN.
Contrast Enhancement in Poor Visibility Conditions Using Guided Filtering
(Společnost pro radioelektronické inženýrství, 2013-06) Chowdhry, Danish Ali; Siddiqui, Adil Masood; Touqir, Imran
In this paper, extraction of atmospheric veil is proposed to enhance the contrast of the images captured under poor visibility conditions. The method based on guided filtering can accurately recover hidden edges, maintain structural similarity (SSIM) to input image and it is effective for both color and gray level images. The proposed algorithm works without prior information about the scene and its complexity is linear function of the input image size. Experimental comparisons with state of the art algorithms demonstrate that our approach can significantly enhance the contrast and restore the visibility in fine details.
A BIC Based Initial Training Set Selection Algorithm for Active Learning and Its Application in Audio Detection
(Společnost pro radioelektronické inženýrství, 2013-06) Leng, Yan; Qi, Guang-hui; Xu, Xin-yan
To construct a classification system or a detection system, large amounts of labeled samples are needed. However, manual labeling is dull and time consuming, so researchers have proposed the active learning technology. The initial training set selection is the first step of an active learning process, but currently there have been few studies on it. Most active learning algorithms adopt random sampling or algorithms like sampling by clustering (SBC) to select the initial training samples. But these two kinds of method would lose their effectiveness in detecting events of small probability. Because sometimes they could not select or select too few samples of the small probability events. To solve this problem, this paper proposes a BIC based initial training set selection algorithm. The BIC based algorithm performs clustering on the whole training set first. Then uses BIC to judge the status of clusters. Finally, it adopts different selection strategies for clusters of different status. Experimental results on two real data sets show that, compared to random sampling and SBC, the proposed BIC based initial training set selection algorithm can efficiently solve the detection problem of small probability events. In the mean time, it has obvious advantages in detecting events of non-small probability.
Design of Dual-band Branch-Line Coupler Based on Shunt Open-Circuit DCRLH Cells
(Společnost pro radioelektronické inženýrství, 2013-06) Lu, Ke; Wang, Guang-ming; Tian, Bo
In this article, the shunt open-circuit dual composite right/left-handed (DCRLH) cell is initially proposed and one dual-band branch-line coupler based on the proposed cells is designed. It is found that, compared with DCRLH cell, the frequency selectivity, matching condition and adjustment range of the shunt open-circuit DCRLH cell improve greatly. Moreover, the shunt open-circuit DCRLH cell exhibits two adjustable frequency points with -90degrees phase shift within its first two passbands. In order to explore this exotic property effectively, the influence of the primary geometrical parameter is investigated through parametric analysis. Thus, one dual-band branch-line coupler based on the shunt open-circuit DCRLH cells is designed. Both simulated and measured results indicate that comparative performance is achieved. Different from part of previous dual-band branch line couplers, for the proposed coupler, the signs of phase difference of two output ports within the two operating frequency bands are identical with each other. This branch-line coupler is quite suitable for the application which is sensitive to the variation of phase difference and its effective area is compact.
Analyses of 100 Gbps Coherent System Performances
(Společnost pro radioelektronické inženýrství, 2013-06) Skoda, Pavel; Radil, Jan; Vojtech, Josef; Hula, Miloslav
This paper presents the results of laboratory and field testing of coherent 100 Gbps system with DP-QPSK modulation. Several measurements were performed including power budget, nonlinear threshold, spectrum filtration, constellation diagram, interoperability with 10 Gbps lambdas and dispersion compensation type impact. Field tests addressed transmission of 100 Gbps signal as an Alien Wavelength through multivendor network, influence of photonic service parallel to 100 Gbps signal and performance of 100 Gbps system over single fiber bidirectional transmission lines. 100 Gbps system has been found extremely resilient to most classical impairments thanks to advances error coding and compatible with standard 10 Gbps NRZ lambdas and any type of dispersion compensation. The system was also working over single fiber bidirectional lines and in parallel with Photonic Service of time transfer. The paper also shows recent results of single hop test with 100 Gbps system in laboratory environment.

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