预测帧编码中基于场景信息的宏块模式跳过算法*

在对场景信息进行分析的基础上,提出了H.264/AVC中预测帧的一种快速算法.对于未发生场景切换的预测帧,采用INTRA模式跳过算法(IMSA),跳过该帧中所有的INTRA模式的决策过程.对于发生场景切换的预测帧,跳过INTER模式的决策过程(PMSA).仿真结果显示,与采用完整的率失真优化(RDO)决策过程相比,未发生场景切换时,所提方法能减少30%～60%的编码时间;发生场景切换时,能减少60%～70%的编码时间,并且未导致明显的图像质量下降和码率的增加.     

工作流技术在ASP公共服务平台中的应用研究*

根据项目特点,建立了适合ASP平台的基于协调理论和反馈机制的扩展活动网络模型,采用XML模式的XPDL规范实现过程定义;然后通过DOM解析XML数据文档和J2EE的技术支持实现了系统的轻量级工作流引擎.详细介绍了系统实现中解决的两个关键问题:事务型操作的处理和并发控制,并提出了基于优先级的锁绑定机制.     

Ensemble deep transfer learning driven by multisensor signals for the fault diagnosis of bevel-gear cross-operation conditions

The existing intelligent fault diagnosis techniques of bevel gear focus on single-sensor signal analysis under the steady operation condition. In this study, a new method is proposed based on ensemble deep transfer learning and multisensor signals to enhance the fault diagnosis adaptability and reliability of bevel gear under various operation conditions. First, a novel stacked autoencoder(NSAE) is constructed using a denoising autoencoder, batch normalization, and the Swish activation function. Second, a series of source-domain NSAEs with multisensor vibration signals is pretrained. Third, the good model parameters provided by the source-domain NSAEs are transferred to initialize the corresponding target-domain NSAEs. Finally, a modified voting fusion strategy is designed to obtain a comprehensive result. The multisensor signals collected under the different operation conditions of bevel gear are used to verify the proposed method. The comparison results show that the proposed method can diagnose different faults in an accurate and stable manner using only one target-domain sample, thereby outperforming the existing methods.     

The dynamic evolution of aggregated lithium dendrites in lithium metal batteries

Lithium (Li) metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li den-drites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current den-sity is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specif-ically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodol-ogy and mechanistic understanding established herein give a significant step toward the practical appli-cations of Li metal anodes.     

预氧化-铁盐沉淀法处理高浓度含砷废水的试验研究

对某砷化镓半导体企业生产过程中产生的高浓度含砷(As)废水,采用过氧化氢(H2 O2)预氧化结合氯化铁(FeCl3)沉淀法进行处理.研究确定了H2O2的投加量,并考察了Fe与As物质的量比、pH值和反应时间等试验条件对砷去除效果的影响.结果表明,当30％H2 O2用量为1.5 mL/L,Fe与As物质的量比为2.5,pH值为8.0,反应时间为2 h时,废水中的总砷浓度可从884 mg/L降低至0.164 mg/L,达到项目环评要求的0.2 mg/L的排放标准.     

N3-Kethoxal-Based Bioorthogonal Intracellular RNA Labeling

There is growing interest in developing intracellular RNA tools. Herein, we describe a strategy for N₃-kethoxal (N₃K)-based bioorthogonal intracellular RNA functionalization. With N₃K labeling followed by an in vivo click reaction with DBCO derivatives, RNA can be modified with fluorescent or phenol groups. This strategy provides a new way of labeling RNA inside cells.     

管桩水泥性能优化与控制方法

预应力高强管桩是采用高标号品种水泥等原料作为原材料,经离心工艺成型后,再通过蒸汽或蒸压养护而成的一种空心圆筒体的等截面混凝土构件,具有脱模快、强度高、施工方便、适用范围广、生产成本低等优点,广泛应用于建筑、港口、码头、铁路、桥梁等基础设施建设工程中[1]。管桩制品厂家一般对水泥强度要求高,尤其是早期强度[2],另外因操作时间不长和对产品外观质量要求较高,相比普通的混凝土,对流动性要求更高。中国葛洲坝水泥有限公司长期向荆州、荆门等地的管桩生产企业供应管桩专用水泥,为更好地满足客户需求,提升公司管桩水泥产品的强度与工作流动性能,开展相关试验研究。     

CHARAC TERIZATION OF TiAl POWDER PRODUCED BY MECHANICAL ALLOYING

The microstructure,alloying reaction and sintering behavior of the powder produced by Mechanical Al-loying(MA)for 8 h from 64 wt.-% Ti powder and 36 wt.-% Al powder were studied by scanning electronmicroscopy,optical microscopy,X-ray diffractometry,differential scanning calorimetry(DSC)and dilatometry.The mechanically alloyed powder partictes are Ti-Al composite particles.Thus,titanium aluminides can formeasily in the powder through diffusion during heat treatment.It is shown that the sintering behavior of this pow-der,different from the behaviors of TiAl alloy powder and mixed powder of 64 wt.-% Ti powder and 36 wt.-%Al powder,changes from expansion at temperatures below 1000℃ to shrinkage at temperatures above 1000℃.Homogeneously alloyed TiAl material with a density over 96% of the theoretical density can be produced fromthe mechanically alloyed powder by compaction-sintering.     

地聚合物混凝土配比及力学性能研究

混凝土是巷道支护过程中的重要建筑材料,然而混凝土在巷道施工中常常出现质量问题,为了不影响正常生产,需要对其进行修补。地聚合物混凝土凝结时间快,早期强度高,界面结合能力强,耐高温性和抗冻性强,耐腐蚀性良好,具有用作修补材料的潜力。以粉煤灰和矿粉为原料,Na₂SiO₃溶液和NaOH为碱激发剂制备地聚合物胶砂,研究不同的碱激发剂模数（1.0、1.2、1.4）和掺量（10%、15%、20%）对不同龄期胶砂力学性能的影响。结果表明：当碱激发剂模数为1.2,碱掺量为15%时,胶砂强度达到最大值。设计正交试验,研究了不同水胶比（0.45、0.50、0.55）、粉煤灰掺量（30%、50%、70%）和砂率（30%、35%、40%）对不同龄期地聚合物混凝土的工作性能和力学性能的影响。结果表明：粉煤灰掺量对抗压强度影响最为显著,水胶比次之,而砂率对强度发展几乎没有影响。最优的配合比为水胶比为0.50,粉煤灰掺量为50%,砂率为35%。