Self-learning residual model for fast intra CU size decision in 3D-HEVC

As an extension of the High Efficiency Video Coding (HEVC) standard, 3D-HEVC requires to encode multiple texture views and depth maps, which inherits the same quad-tree coding structure as HEVC. Due to the distinct properties of texture views and depth maps, existing fast intra prediction approaches were presented for the coding of texture views and depth maps, respectively. To further reduce the coding complexity of 3D-HEVC, a self-learning residual model-based fast coding unit (CU) size decision approach is proposed for the intra coding of both texture views and depth maps. Residual signal, which is defined as the difference between the original luminance pixel and the optimal prediction luminance pixel, is firstly extracted from each CU. Since residue signal is strongly correlated with the optimal CU partition, it is used as the feature of each CU. Then, a self-learning residual model is established by intra feature learning, which iteratively learns the features of the previously encoded coding tree unit (CTU) generated by itself. Finally, a binary classifier is developed with the self-learning residual model to early terminate CU size decision of both texture views and depth maps. Experimental results show the proposed fast intra CU size decision approach achieves 33.3% and 49.3% encoding time reduction on average for texture views and depth maps with negligible loss of overall video quality, respectively.     

应用组合起泡剂优化黑、白钨混合浮选

针对湖南某钨选厂使用杂醇类起泡剂BK205所产生的泡沫小、性脆、泡沫层薄等不利于二次浮选的特点,采用BK205与新型醚类起泡剂CU组合使用以便实现矿石中钨矿物的高效回收。结果表明,在采用BK205与新型醚类起泡剂CU组合质量比为3∶1、先BK205后CU的加药方式下,小型闭路试验得到精矿WO3品位为30.13%,回收率为78.98%。工业试验表明,组合起泡剂不仅改善浮选泡沫,减少药剂用量,降低药剂成本,而且能获得比原起泡剂更好的工业指标,使钨矿物得到更高效的回收。     

CU encoding depth prediction,early CU splitting termination and fast mode decision for fast HEVC intra-coding

High Efficiency Video Coding (HEVC) is a new video coding standard achieving about a 50% bit rate reduction compared to the popular H.264/AVC High Profile with the same subjective reproduced video quality. Better coding efficiency is attained, however, at the cost of significantly increased encoding complexity. Therefore, fast encoding algorithms with little loss in coding efficiency is necessary for HEVC to be successfully adopted for real applications. In this paper we propose a fast encoding technique applicable to HEVC all intra encoding. The proposed fast encoding technique consists of coding unit (CU) search depth prediction, early CU splitting termination, and fast mode decision. In CU search depth prediction, the depth of encoded CU in the current coding tree unit (CTU) is limited to predicted range, which is mostly narrower than the full depth range. Early CU splitting skips mode search of its sub-CUs when rate distortion (RD) cost of current CU is below the estimated RD cost at the current CU depth. RD cost and encoded CU depth distribution of the collocated CTU of the previous frame are utilized both to predict the encoding CU depth search range and to estimate the RD cost for CU splitting termination. Fast mode decision reduces the number of candidate modes for full rate distortion optimized quantization on the basis of the low complexity costs computed in the preceding rough mode decision step. When all these three methods are applied, proposed fast HEVC intra encoding technique reduces the encoding time of the reference encoder by 57% on the average, with only 0.6% of coding efficiency loss in terms of Bjontegaard delta (BD) rate increase under the HEVC common test conditions.     

Dissolution of Al2Cu phase in non-modified and Sr modified 319 type alloys

Abstract

This study investigates the effects of solution heat treatment on dissolution of the Al₂Cu phase in non-modified and 150 ppm Sr modified 319 type alloys. Experimental and industrial 319 alloys containing different Mg levels (0, 0·3 and 0·6 wt-%) were used for this purpose. Electron probe microanalysis (EPMA) in conjunction with energy dispersive X-ray (EDX) analysis was used to monitor the distribution of Cu in the matrix and to measure the undissolved Al₂Cu phase. In as cast 319 alloys, copper segregates at the dendrite boundaries. The addition of Mg and Sr may cause this segregation to deteriorate. After heat treatment, the copper begins to distribute more evenly across the dendrite as well as in the matrix. The amount of Cu dissolved in the matrix increases with increasing solution time and temperatures, reaching a maximum for the 490°C/8 h solution heat treatment. The dissolution process of eutectic and block like Al₂Cu was also investigated.     

Crystallisation by laser for Zr based bulk metallic glass

Abstract

Bulk metallic glasses (BMGs) show high amorphous phase stability. The solidification process of BMG occurs with the cessation of epitaxial crystal growth. For a laser heated and melted surface of BMG, crystallisation occurs during cooling, along with crystalline growth from the heat affected zone. Such crystallisation stops at a certain location where the residual melt solidifies as amorphous. The amorphous formation can occur after crystal nucleation. Thermal treatment using a diode laser was used for surface modification of 2 mm thick Zr₅₅Al₁₀Ni₅Cu₃₀ (at.-%) BMG plates. When laser conditions (scanning speed, defocused irradiated spot size and output power) were changed, the maximum temperature and heating cooling rate were changed, and microstructures were changed. Cessation of crystallisation was observed.     

Effect of powder characteristics on Cr internal oxidation for preparation of Cr2O3/Cu composite

Abstract

Cr O₃/Cu composite was prepared by the internal oxidation of Cu–Cr pre-alloyed powders formed by high energy milling. Effects of milling time on the internal oxidation characteristics of Cu–Cr pre-alloyed powders were also discussed in this paper. The results indicate that the degree of the internal oxidation continually increases with prolonged milling time. At the initial stage, external oxidation rather than internal oxidation occurs, resulting in coarse Cr₂O₃ particles. With further milling, the internal oxidation becomes more complete and the sizes of Cr₂O₃ particles also become finer and well distributed. The properties of the composite are therefore improved. A high quality composite specimen from Cu–1·0Cr pre-alloyed powders after 40 h milling was prepared by the internal oxidation process. The Cr₂O₃ particles with an average size of 2–5 μm in diameter and about 5–10 μm in particles space were found by a microstructure examination, and they were uniformly dispersed in the Cu matrix.     

Interfacial reaction and mechanical reliability of eutectic Sn–0·7Cu/immersion Ag-plated Cu solder joint

Abstract

In this study, the interfacial reaction and joint reliability of immersion Ag-plated Cu substrate with the Sn–0·7Cu (wt-%) ball–grid array (BGA) solder was investigated. During reflow, the Ag plating layer was dissolved completely into the molten Sn–Cu solder and some of the Cu layer was also dissolved into the molten solder. The dissolved Ag and Cu were precipitated as Ag₃Sn and Cu₆Sn₅ intermetallic compounds (IMCs) in the solder matrix. Upon reflow, the Sn–Cu solder exhibits an off-eutectic reaction to produce the eutectic phase and precipitate (Cu₆Sn₅ and Ag₃Sn). The Cu–Sn IMC layer was formed at the solder/Cu interface after reflow, and the IMC layer grew during aging treatment. During the shear tests, the failure mode switched from a bulk-related failure to an interface-related failure. After aging for 250 h, the joint failed partially at the solder/Cu₆Sn₅ interface. The brittle fracture was linked to the formation of thick Cu–Sn IMC layer.     

铸态锰白铜合金时效工艺的研究

对铸态锰白铜白合金的时效强化进行了探索性地试验和研究，结果表明：在400-470℃直接进行时效72h以上，可以达到理想的强化效果。     

Application of an analytical phase transformation model

Employing isothermal and isochronal differential scanning calorimetry, an analytical phase transformation model was used to study the kinetics of crystallization of amorphous Mg82.3Cu17.7 and Pd40Cu30P20Ni10 alloys. The analytical model comprised different combinations of various nucleation and growth mechanisms for a single transformation. Applying different combinations of nucleation and growth mechanisms, the nucleation and growth modes and the corresponding kinetic and thermodynamic parameters, have been determined. The influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics with the increase of pre-annealing can be analyzed. The results show that the changes of the growth exponent, n, and the effective overall activation energy Q, occurring as function of the degree of transformation, do not necessarily imply a change of nucleation and growth mechanisms, i.e. such changes can occur while the transformation is isokinetic.     

考虑球面副间隙的4-SPS/CU并联机构动力学分析

基于机械系统动力学方程的增广法建立考虑球面副间隙的4-SPS/CU并联机构动力学模型。为了简化该并联机构的动力学模型,通过质量矩的方法视驱动支链为一个整体。根据含间隙球面副元素的接触方式建立该间隙运动副的运动学模型,求出含间隙球面副元素之间的接触变形量与相对接触速度。考虑到接触体之间接触刚度与机械系统动力学模型之间的耦合性,以非线性刚度系数代替Flores接触模型中的常数刚度系数而提出一种改进的接触力模型,并基于该接触力模型利用接触变形量与相对法向接触速度建立间隙运动副元素之间的法向接触力模型,为了保证数值运算的稳定性,采用具有动态修正系数的Coulomb摩擦模型,建立接触体之间的切向接触力模型。进一步把间隙运动副元素之间的接触力转换到该间隙运动副所连接的驱动支链和上平台的质心上,并把该接触力集成到4-SPS/CU并联机构动力学模型的广义力中,从而成功引入了关节间隙效应,采用Baumgarte稳定约束法避免了积分过程中的约束违约问题。通过数值分析预测球面副间隙对4-SPS/CU并联机构动力学性能的影响。