Analysis of Coding Gain Due to In-Loop Reshaping.

Reshaping, a point operation that alters the characteristics of signals, has been shown capable of improving the compression ratio in video coding practices. Out-of-loop reshaping that directly modifies the input video signal was first adopted as the supplemental enhancement information (SEI) for the HEVC/H.265 without the need to alter the core design of the video codec. VVC/H.266 further improves the coding efficiency by adopting in-loop reshaping that modifies the residual signal being processed in the hybrid coding loop. In this paper, we theoretically analyze the rate-distortion performance of the in-loop reshaping and use experiments to verify the theoretical result. We prove that the in-loop reshaping can improve coding efficiency when the entropy coder adopted in the coding pipeline is suboptimal, which is in line with the practical scenarios that video codecs operate in. We derive the PSNR gain in a closed form and show that the theoretically predicted gain is consistent with that measured from experiments using standard testing video sequences.

Accurate contactless sleep apnea detection framework with signal processing and machine learning methods.

The detection of sleep apnea is critical for assessing sleep quality. It is also a proven biometric in diagnosing cardiovascular and other diseases. Recent studies have shown that radar-based non-contact vital sign monitoring system can effectively detect sleep apnea. However, the detection accuracy in the current study still needs to be improved. In this paper, we propose a sleep apnea detection framework based on FMCW radar. First, the radar system is employed to record the sleep data throughout the night with polysomnography (PSG) comparison. Then, in order to extract more accurate respiratory signal from the raw radar data, the signal processing methods are investigated to solve the observed discontinuity phenomenon. Finally, machine learning methods are adopted. The apneic and not-apneic events are classified accurately by selecting effective features of respiratory signal. As shown in the experimental results, the proposed system could achieve a good classification performance with an accuracy of 95.53%, a sensitivity of 72.60%, a specificity of 97.32%, a Kappa of 0.68, and an F-score of 0.84.

Efficient Depth Intra Frame Coding in 3D-HEVC by Corner Points.

To improve the coding performance of depth maps, 3D-HEVC includes several new depth intra coding tools at the expense of increased complexity due to a flexible quadtree Coding Unit/Prediction Unit (CU/PU) partitioning structure and a huge number of intra mode candidates. Compared to natural images, depth maps contain large plain regions surrounded by sharp edges at the object boundaries. Our observation finds that the features proposed in the literature either speed up the CU/PU size decision or intra mode decision and they are also difficult to make proper predictions for CUs/PUs with the multi-directional edges in depth maps. In this work, we reveal that the CUs with multi-directional edges are highly correlated with the distribution of corner points (CPs) in the depth map. CP is proposed as a good feature that can guide to split the CUs with multi-directional edges into smaller units until only single directional edge remains. This smaller unit can then be well predicted by the conventional intra mode. Besides, a fast intra mode decision is also proposed for non-CP PUs, which prunes the conventional HEVC intra modes, skips the depth modeling mode decision, and early determines segment-wise depth coding. Furthermore, a two-step adaptive corner point selection technique is designed to make the proposed algorithm adaptive to frame content and quantization parameters, with the capability of providing the flexible tradeoff between the synthesized view quality and complexity. Simulation results show that the proposed algorithm can provide about 66% time reduction of the 3D-HEVC intra encoder without incurring noticeable performance degradation for synthesized views and it also outperforms the previous state-of-the-art algorithms in term of time reduction and ∆ BDBR.

Study on the molecular-epidemiological characteristics of HIV-1 in Shenzhen, 1992- 2008 / 中华流行病学杂志

Objective To investigate the epidemiological characteristics of HW-1 subtype in Shenzhen from 1992 to 2008.Methods 489 HIV-1 positive plasma samples were collected from 1992 to 2008 in Shenzhen.HIV-1 env genes were amplified by nested-PCR from RNA.Phylogenetic analysis was performed on data regarding the nucleotide sequence.Results A total of 464 sequences were amplified and genotyped.Data from this study revealed that CRF01_AE was a predominant HIV-1 subtype in Shenzhen (64.4％,299/464),followed by subtypes CRF_BC( 17.5％,81/464),B'( 14.7％,68/464) and B (2.4％,11/464).Subtype C (0.4％,2/464),A1 (0.2％,1/464),CRF02_AG(0.2％,1/464) and CRF06_cpx (0.2％,1/464) were also prevalent in Shenzhen.CRF01_AE and CRF_BC were predominant among heterosexuals,homosexuals and injection drug users,while B'was predominant among blood donors.Results from phylogenetic tree analysis showed that some of the HIV-1 clusters had been defined in CRF01_AE strains at different time or groups with different transmission routes.Cross-infections were also seen.Conclusion CRF01_AE was the predominant HIV-1 subtype in Shenzhen while CRF_BC,B,B',C,A1,CRF02_AG and a small amount of CRF06_cpx or recombinant subtypes were prevalent in this city.Different subtypes showed great variation in the process of epidemics.

Spatial and temporal patterns of primary and secondary syphilis in Shenzhen, China / 中华流行病学杂志

Objective To learn the spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen and to provide evidence for carrying out further research on syphilis.Methods Primary syphilis and secondary syphilis cases among residents in Shenzhen between 2005and 2009(n=11 303) were geocoded at street office level (n=55) based on residence at the time of diagnosis. Both spatial and space-time scan statistics were used to identify clusters of street office by using SaTScan software. Results In the purely spatial analyses, clusters were seen in the junction of the Baoan district and Nanshan district (Xinan, Xixiang, Nanshan and Nantou street office) and in the region near Hong Kong (Dongmen, Shekou, and Futian street office), as well as in the other streets where entertainment industry was relatively developed (Longhua, Huafu, Huangbei and Cuizu street office). The clusters had not changed much in the first four years, but nine clusters appeared in 2009.Annually, the most likely clusters were located in Longhua (2005, P≤0.001, RR=3.34), Bamboo (2006, P≤0.001, RR=9.59), Huafu (2007, 2008 years, P≤0.001, RR values were 4.18 and 4.75)and Cuizu (2009, P≤0.001, RR=8.02). In the space-time scan analysis, we found 16 significant clusters, which were similar to the pure spatial analyses. However, regional difference were also found, with the most likely cluster was the Guiyuan street office in 2006. Conclusion Spatial and space-time scan statistics seemed to be effective ways in describing the circular disease clusters. We have had a better understanding on spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen through spatial and space-time scan statistics of syphilis surveillance data in the recent years. The changes of spatial and temporal patterns of primary syphilis and secondary syphilis were also described by SaTScan software, which also provided useful reference for the preventive strategies on sexually transmitted diseases as well as on HIV. Useful information was also provided for financial investment and cost-effective studies.

Study on the status of syphilis infection and its influence factors on pregnant women in Shenzhen / 中华流行病学杂志

<p><b>OBJECTIVE</b>Through questionnaire and screening, epidemiology of syphilis in pregnant women and related risk factors were studied, to develop effective policy and reducing the negative impact of the disease.</p><p><b>METHODS</b>All pregnant women who appeared at the hospitals the first time, were included, in Shenzhen city. Tolulized Red Unheated Serum Test (TRUST) method was used for primary screening and positive results were confirmed by the Treponema Pallidum Particle Agglutination (TPPA) test at the Shenzhen Center for Disease Control and Prevention (SZCDC). Positive patients were informed and treated and the pregnancies were managed accordingly at the SZCDC.</p><p><b>RESULTS</b>From 2003-2005, 418,871 (94.7%) pregnant were screened. Epidemiological and treatment data were collected from 2019 positive cases of infectious syphilis (0.48%). Among them, 94.2% were between 20 and 35 years old, with 93.6% of them had only junior high school education and 63.4% of them worked as commercial services or jobless which was significantly higher than other occupations (OR = 8.628). 89.5% of them were from other cities, significantly higher than from local residents (OR = 8.733). Gestational weeks at original diagnosis was longer and the infection rate higher.</p><p><b>CONCLUSION</b>The infection rate of syphilis in Shenzhen was still at a high level which was related to occupation, education level, place of residency, gestational weeks at first diagnosis etc. Further screening measures and early intervention were important.</p>

New architecture for MPEG video streaming system with backward playback support.

MPEG digital video is becoming ubiquitous for video storage and communications. It is often desirable to perform various video cassette recording (VCR) functions such as backward playback in MPEG videos. However, the predictive processing techniques employed in MPEG severely complicate the backward-play operation. A straightforward implementation of backward playback is to transmit and decode the whole group-of-picture (GOP), store all the decoded frames in the decoder buffer, and play the decoded frames in reverse order. This approach requires a significant buffer in the decoder, which depends on the GOP size, to store the decoded frames. This approach could not be possible in a severely constrained memory requirement. Another alternative is to decode the GOP up to the current frame to be displayed, and then go back to decode the GOP again up to the next frame to be displayed. This approach does not need the huge buffer, but requires much higher bandwidth of the network and complexity of the decoder. In this paper, we propose a macroblock-based algorithm for an efficient implementation of the MPEG video streaming system to provide backward playback over a network with the minimal requirements on the network bandwidth and the decoder complexity. The proposed algorithm classifies macroblocks in the requested frame into backward macroblocks (BMBs) and forward/backward macroblocks (FBMBs). Two macroblock-based techniques are used to manipulate different types of macroblocks in the compressed domain and the server then sends the processed macroblocks to the client machine. For BMBs, a VLC-domain technique is adopted to reduce the number of macroblocks that need to be decoded by the decoder and the number of bits that need to be sent over the network in the backward-play operation. We then propose a newly mixed VLC/DCT-domain technique to handle FBMBs in order to further reduce the computational complexity of the decoder. With these compressed-domain techniques, the proposed architecture only manipulates macroblocks either in the VLC domain or the quantized DCT domain resulting in low server complexity. Experimental results show that, as compared to the conventional system, the new streaming system reduces the required network bandwidth and the decoder complexity significantly.

[Development of a shock response spectrum test facility].

OBJECTIVE: To develop a shock response spectrum test facility for testing space products in the pyrotechnic environments. METHOD: The natural frequencies of the resonant plate, a key part of the facility, were calculated with finite element method. The dynamic response of the whole system was simulated when the machine was excited by a real shock generated by a dropping hammer. A shock response spectrum test facility was developed under the guide of the simulation results. RESULT: The resonant plate drop machine could simulate pyrotechnic shock by adjusting the force, the natural frequencies of the plate and the damping materials above and under the plate. CONCLUSION: The agreement between the measurement and the simulation indicates that the computer simulation results are reliable. It is feasible to use the resonant plate drop machine to simulate pyrotechnic environment.