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Screen content coding (SCC) is increasingly used in mobile devices, and ultralow coding complexity is required for low power consumption. This article proposes an ultralow complexity string matching approach to SCC. The proposed approach has two essential features: 1) allowing only two types of most effective reference strings that have two most frequently occurring values of offset (i.e., displacement vector) named dual unity offset and 2) fully optimized coding of string matching parameters for maximum coding efficiency. Since at most only two offset values and corresponding reference string positions are allowed for any current string being coded, the optimal reference string searching process is extremely simple and only needs to select the best string from at most two candidates. Moreover, in the proposed approach, the value ranges of string matching parameters, i.e., the string offset vector and string length are very limited, resulting in few bits to code the two parameters and high coding efficiency. Compared with the AVS3 reference software HPM7.0 with IBC disabled, using AVS3 SCC common test condition and YUV test sequences in text and graphics with motion category, the proposed technique achieves Y average BD-rate reduction of 10.8% and 5.8% for all intra (AI) and low-delay B (LDB) configurations, respectively, at ultralow encoding and decoding complexity. [ABSTRACT FROM AUTHOR]

We consider visual tracking in numerous applications of computer vision and seek to achieve optimal tracking accuracy and robustness based on various evaluation criteria for applications in intelligent monitoring during disaster recovery activities. We propose a novel framework to integrate a Kalman filter (KF) with spatial-temporal regularized correlation filters (STRCF) for visual tracking to overcome the instability problem due to large-scale application variation. To solve the problem of target loss caused by sudden acceleration and steering, we present a stride length control method to limit the maximum amplitude of the output state of the framework, which provides a reasonable constraint based on the laws of motion of objects in real-world scenarios. Moreover, we analyze the attributes influencing the performance of the proposed framework in large-scale experiments. The experimental results illustrate that the proposed framework outperforms STRCF on OTB-2013, OTB-2015 and Temple-Color datasets for some specific attributes and achieves optimal visual tracking for computer vision. Compared with STRCF, our framework achieves AUC gains of 2.8%, 2%, 1.8%, 1.3%, and 2.4% for the background clutter, illumination variation, occlusion, out-of-plane rotation, and out-of-view attributes on the OTB-2015 datasets, respectively. For sporting events, our framework presents much better performance and greater robustness than its competitors. [ABSTRACT FROM AUTHOR]

In DC metro systems, the stray current may cause many challenges for the nearby metal structures and the AC power systems, such as the corrosion of the buried pipes and the grounding grids of substations. Therefore, calculating the stray current and analyzing the distribution characteristics of the stray current are necessary for the design of the buried pipelines and substations. To obtain the stray current, considering the through-type structure characteristics of the return current system and the traction power supply system, a multiple power supply sections simulation model (multiple-section model) of stray current is proposed. In the proposed model, the train is equivalent to two dc current sources, and the dynamic results can be completed. Through comparing the rail potentials of simulation results and the field test data of the Shenzhen metro line, the proposed model is verified. And based on the proposed model of the Shenzhen metro line, the stray current distributions are obtained and analyzed. The results indicate that the stray current distribution has a certain periodicity which is approximately equal to the headway time of the train. [ABSTRACT FROM AUTHOR]

Alpha channel is being applied in an increasing number of mobile web applications on mobile devices that require ultra-low power consumption in all cases including compute-intensive video encoding and decoding. Thus, we propose an ultra-low coding complexity and high efficiency alpha channel lossless coding approach. A novel coding framework and four new coding schemes are proposed for alpha channel coding. The framework fuses a string matching technique and a proposed prediction coding scheme named bit-depth preserving prediction (BDPP) together to reduce the correlations within and between repeated identical patterns and neighboring pixels. To achieve a good tradeoff between complexity and efficiency, either the unmatchable bytes are coded directly or the BDPP residuals of unmatchable bytes are coded by a proposed bytewise entropy coding scheme named 0.5-1-2byte-size-code. The other string matching parameters are coded by another proposed bytewise entropy coding scheme named byte-size multi-variable-length-code. To speed up the string-matching search, we apply a fast string search scheme that combines special position search and hash-based search. For the selected typical 236 alpha test images, compared with x265 in the fastest configuration and lossless mode, the proposed lossless approach achieves 14.33% less total compressed bytes with only 2.75% encoding and 1.83% decoding runtime. The proposed approach also outperforms the conventional lossless coding techniques such as LZ4HC, ZLIB, and PNG. [ABSTRACT FROM AUTHOR]

Regenerative braking energy feedback system (RBEFS) can effectively feed the regenerative braking energy (RBE) of the trains back to the ac power grid. This improves the economy of the urban rail transit system greatly. The RBEFS that is utilized for both recycling the RBE and controlling the voltage of the traction network is proposed in this paper. First, the structure of the medium voltage RBEFS with the higher recovery efficiency is presented, and its parameters are designed in detail. Then, the double closed-loop control strategy of the RBEFS is studied, which not only achieves unit power factor feedback but also stabilizes the voltage of traction network effectively. Finally, simulation based on MATLAB/Simulink, laboratory experiments, and the field test are used to verify the performance of the presented RBEFS. The simulation and experiments results show that the RBEFS is able to feed RBE back into the ac grid effectively and the power quality of its output current satisfies the requirements of grid connection, as well as mitigate the voltage rise of the traction network under different startup threshold perfectly. [ABSTRACT FROM AUTHOR]

This paper proposes a universal string matching (USM) approach to screen content coding (SCC). USM uses a primary reference buffer and a secondary reference buffer for string matching and includes three modes: general string (GS) mode, constrained string 1 (CS1) mode, and constrained string 2 (CS2) mode. The CS1 mode and CS2 mode are constrained cases of the GS mode. Due to the diversity of the screen content, each of the three modes plays an indispensable role in coding some types of screen content. When using USM to code a coding unit (CU), one of the three modes is selected to code the CU. Compared with high-efficiency video coding (HEVC) SCC reference software HM-16.6 + SCM-5.2 of full frame search range for intrablock copy, USM achieves an average Y BD-rate of –28.4% for five text and graphics with motion (TGM) sequences from the audio video coding standard SCC common test condition (CTC) test suite and –5.8% for eight TGM test sequences from the HEVC SCC CTC test suite in all intraconfigurations, with a nearly 10% decrease in encoding runtime and almost the same decoding runtime. [ABSTRACT FROM PUBLISHER]