A novel rate control initialization algorithm for H.264

Wei Wu,Hae Kwang Kim IEEE 2009 IEEE TRANSACTIONS ON CONSUMER ELECTRONICS - Vol.55 No.2

<P>This paper presents a novel rate control initialization algorithm for H.264. Firstly the first instantaneous decoding refresh frame in a video sequence is intra-coded to get the mean absolute difference (MAD) value, then the average MAD value of the second, third and fourth frames which are inter-coded is computed, finally the initial quantization parameter is determined depending on the bits per pixel and the two MAD values. When compared with the algorithm JVT-G012 (2003) which is the current recommended algorithm implemented in the H.264 reference software JM13.0 and the algorithm by H.Wang and S.Kwong (see IEEE Trans. Circuits Syst. Video Techno!., vol.18, no.1, p.140-4, Jan. 2008), the proposed algorithm can increase the average peak signal-to-noise ratio of reconstructed video by up to 1.241 dB and 1.262 dB, respectively.</P>

Rate Control Initialization Scheme for H.264/AVC

Wei Wu,Hae Kwang Kim 대한전자공학회 2008 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

In this paper, a novel rate control initialization scheme for H.264/AVC is proposed. The current recommended rate control initialization scheme implemented in the H.264 reference software JM13.0 does not take into account the coding complexity of video sequence to determine the initial quantization parameter (QP). In the proposed scheme, a new model is exploited for the relation between mean absolute difference (MAD) and quantization step (QS) of the first instantaneous decoding refresh (IDR) picture, then a linear rate-quantization (R-Q) model for the first IDR picture is described, finally the initial QP can be determined according to the two models and the target sum bits for the first IDR picture. Experiment results show that the proposed scheme can achieve better quality than the current scheme in JM13.0, and the average luminance peak signal-to-noise-ratio (PSNR) is increased by up to 1.21 ㏈ under the IPPP structure and 1.46 ㏈ under the IBPBP structure.

DC Coefficient Distributions for P-Frames in H.264/AVC

Wei Wu,Bin Song 한국전자통신연구원 2011 ETRI Journal Vol.33 No.5

In this letter, the distributions of direct current (DC) coefficients for P-frames in H.264/AVC are analyzed, and the distortion model of the Gaussian source under the quantization of the dead-zone plus-uniform threshold quantization with uniform reconstruction quantizer is derived. Experimental results show that the DC coefficients of P-frames are best approximated by the Laplacian distribution and the Gaussian distribution at small quantization step sizes and at large quantization step sizes, respectively.

Novel Ceramides from Aerial Parts of Saussurea involucrata Kar. et. Kir.

Wei Wu,Yang Qu,Huiyuan Gao,Jingyu Yang,Jianguo Xu,Lijun Wu 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.9

Novel ceramides, together with nine known compounds were isolated from aerial parts of the Saussurea involucrata Kar. et. Kir. The novel structures were determined by spectroscopic methods and microscale chemical degradation. The ceramides showed appreciable cytotoxicity against three human tumor cell lines including human promyelocytic leukemia (HL-60), human melanoma (A375-S2) and human cervical carcinoma (HeLa) cell lines. The results suggested that this class of ceramides may have potential as an antitumor agent.

Novel Rate Control Scheme for Low Delay Video Coding of HEVC

Wei Wu,Jiong Liu,Lei Feng 한국전자통신연구원 2016 ETRI Journal Vol.38 No.1

In this paper, a novel rate control scheme for low delay video coding of High Efficiency Video Coding (HEVC) is proposed. The proposed scheme is developed by considering a new temporal prediction structure of HEVC. In the proposed scheme, the relationship between bit rate and quantization step is exploited firstly to formulate an accurate quadratic rate-quantization (R-Q) model. Secondly, a method of determining the quantization parameters (QPs) for the first frames within a group of pictures is proposed. Thirdly, an accurate frame-level bit allocation method is proposed for HEVC. Finally, based on the proposed R-Q model and the target bit allocated for the frame, the QPs are predicted for coding tree units by using rate-distortion (R-D) optimization. We compare our scheme against that of three other state-of-the-art rate control schemes. Experimental results show that the proposed rate control scheme can increase the Bjøntegaard delta peak signal-to-noise ratio by 0.65 dB and 0.09 dB on average compared with the JCTVC-I0094 and JCTVC-M0036 schemes, respectively, both of which have been implemented in an HEVC test model encoder; furthermore, the proposed scheme achieves a similar R-D performance to Wang’s scheme, as well as obtaining the smallest bit rate mismatch error of all the schemes.

THREE-DIMENSIONAL NUMERICAL MODELING OF SALINE INTRUSION AND PURGING IN SEA OUTFALLS

WEI WU,JIHONG XIA,ZHONGMIN YAN,NING ZHU,PENG LIU 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Fluid Pressure Heterogeneity in Rock Fractures and Its Influence on Injection-induced Earthquake Prediction

( Wei Wu ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Fluid injection into a highly heterogeneous fault causes the build-up of localized fluid pressure and initiates the rupture of pressurized fault segment. The rupture front may propagate along the fault subjected to tectonic stress and finally trigger a large earthquake. We carry out a suite of triaxial shear-flow experiments on sawcut fractures in granite to reproduce the injection-induced fracture instability due to heterogeneous fluid pressure distribution. When distilled water is injected at one side of a sawcut fracture in a granite sample subjected to triaxial compression, the pore pressure measured at the other side of the fracture rises at different increasing rate depending on the permeability of the fracture. We find that when the pore pressure is homogeneously distributed in a high-permeability fracture, the fracture instability is mainly due to the near-uniform reduction of effective normal stress. If the fracture permeability is low, the pore pressure amplifies near the injection borehole, and induces fracture rupture propagating in the unpressurized area. The pore pressure can only perturb limited area around the borehole in an extremely low-permeability fracture, and the entire fracture remains stable. The relationship between the seismic moment release and fluid injection volume assumes the uniform distribution of injected fluid in fault, and may not reasonably predict the seismic moment release due to the rupture of highly heterogeneous fault. This study provides a possible explanation of ~800 times unexpected seismic energy released during Pohang earthquake.

An Optimization Model on Virtual Machines Allocation Based on Radial Basis Function Neural Networks

Wei Wu,Wencai Du,Hui Zhou,Jiezhuo Zhong,Zhen Guo 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.6

Properly allocation of virtual machines is important for computing infrastructures scheduling. This paper presents systemic method on virtual machine array optimization control based on artificial intelligence and matrix control theory. According to request service data from users to provide proper VMs roughly via intelligent pattern recognition based on RBFNN, the data is sent to a multiple-targets optimization process to produce VMs allocation matrix precisely, thus enable to minimize the cast and enhance efficiency of the whole array to achieve low consumption optimization and ensure the stability of the system. Simulation experiments confirmed the effectiveness of this model and adaption ability in online dynamics.

Uniaxial Compression Properties and Compression Fatigue Performance of Selective Laser Melted Ti–6Al–4V Cellular Structure

Ming‑Wei Wu,Jhewn‑Kuang Chen,Mo‑Kai Tsai,Pei Wang,Tien‑Lin Cheng,Bo‑Huan Lin,Po‑Hsing Chiang,Annadurai Dhinakar 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1

The selective laser melted (SLM) Ti–6Al–4V cellular solid is a promising material in biomedical and other applications. The mechanical properties of the SLM Ti–6Al–4V cellular material are predominantly controlled by the design of the cellular structure. The objective of this study was to investigate the uniaxial compressive properties and compressive fatigueperformance of the SLM Ti–6Al–4V cellular solid with a new cuboctahedron unit cell reinforced by four diagonal strutsand two horizontal struts along the X and Y axes. The infuences of hot isostatic pressing (HIP) on the various mechanicalproperties were also examined. The results showed a smoother stress–strain curve and fewer stress oscillations in the HIPspecimen than in the SLM specimen. The HIP process slightly decreased the yield strength of the SLM sample from 55 to52 MPa. Under uniaxial compressive stress, the SLM and HIP specimens exhibited layer-by-layer fracture and diagonalshear fracture, respectively. Furthermore, the HIP treatment signifcantly increased the fatigue performance and improved thefatigue endurance ratio at 106cycles from 0.15 to 0.35. The HIP treatment contributed to several positive efects, includingphase transformation from brittle α′ to α + β, the elimination of strut porosity and residual stress, an increase in lath size,and a better combination of strength and ductility, thereby improving the fatigue performance. The efects of stress mode onthe fracture mechanism were also clarifed using in situ observation in combination with digital image correlation.

Effect of Low-Temperature Heat Treatment on PM2.5 Adsorption Properties of GO Films

Weiwu Zou,Baoshan Gu,Shiqing Sun,Shidong Wang,Xin Li,Haoqi Zhao,Peiyan Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.15 No.01

To explore the mechanism of GO acting on PM 2.5, a graphene oxide (GO) film was prepared via a spraying method for air purification. The effects of different media, temperature and heat treatment times on the adsorption of PM 2.5 on GO film were investigated. The morphology, composition and structure of GO materials were characterized by scanning electron microscopy (SEM), electron spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR) and Raman spectroscopy. When the vacuum heat-treatment temperature is below 80 ℃ and the atmospheric heat-treatment temperature is below 100 ℃, the air purification performance of the film does not change significantly. With the increase in the vacuum heat-treatment temperature, the removal efficiency of PM 2.5 by GO film decreases gradually from 95% to 83%. At different times, the vacuum heat treatment increases with time, and the film removal rate shows a downward trend. As the heat-treatment temperature and time increase, a certain redox reaction occurs in the GO, and the air purification performance decreases. At a temperature of 120 ℃ and a time of 8 h, the removal rate drops to 81.68%. The adsorption of PM 2.5 by GO film mainly relies on the action of oxygen-containing functional groups.