复方降脂中药的性味归经与药效的BPNN研究

针对复方中药药效与其性味归经之间复杂的、不确定的关系,建立适于复方降脂中药的BP神经网络模型,运用Matlab快速预测复方降脂中药的药效指标。经验证,该方法为一种快速、可靠的方法。     

两栖机器人轮桨腿驱动机构多目标优化设计

提出了一种既能够在陆地上爬行,又能够在一定深度的水下浮游和在海底爬行的新概念轮桨腿一体化两栖机器人;多运动模式和复合移动机构是该机器人的突出特点．分析了轮桨腿复合式驱动机构的运动机理,并采用多目标优化设计理论和算法,对驱动机构的爬行性能和浮游特性进行了综合优化,得到了两栖机器人驱动机构的结构优化参数．虚拟样机的仿真结果证明了该轮桨腿一体化两栖机器人驱动机构的综合运动性能良好,对非结构环境具有一定的适应能力．     

Voltage Decay of Li-Rich Layered Oxides: Mechanism,Modification Strategies,and Perspectives

Li-rich layered oxides (LLOs) have been considered as the most promising cathode materials for achieving high energy density Li-ion batteries. However, they suffer from continuous voltage decay during cycling, which seriously shortens the lifespan of the battery in practical applications. This review comprehensively elaborates and summarizes the state-of-the-art of the research in this field. It is started from the proposed mechanism of voltage decay that refers to the phase transition, microscopic defects, and oxygen redox or release. Furthermore, several strategies to mitigate the voltage decay of LLOs from different scales, such as surface modification, elemental doping, regulation of components, control of defect, and morphology design are summarized. Finally, a systematic outlook on the real root of voltage decay is provided, and more importantly, a potential solution to voltage recovery from electrochemistry. Based on this progress, some effective strategies with multiple scales will be feasible to create the conditions for their commercialization in the future.     

半固态触变挤压对ZA27合金组织和力学性能的影响

通过与常规铸造方法的比较,研究半固态触变挤压对ZA27合金变质、热处理组织和力学性能的影响。结果表明:半固态挤压态合金的密度较铸态合金提高了3%,合金经Sc变质或者半固态挤压都获得了细小而均匀的近似球状组织,而Sc变质结合半固态挤压的球状组织具有最高的圆整度;经T6热处理的半固态挤压合金由细小的初生α相和共析(α+η)组织组成,说明半固态挤压可促进ε相溶解、减少三元共晶(β+η+ε)组织的含量。力学性能测试表明,ZA27合金经半固态挤压+Sc变质+T6热处理后其抗拉强度,伸长率和布氏硬度分别达到586.01MPa,17.57%及171HB。     

发动机进气系统高通量富氧膜的研制

采用交联改性的方法对较低分子量的乙烯基硅橡胶进行了改性研究,制备了高通量的富氧膜,结合单因素实验法和Design-expert正交实验设计,考察了原料配比、交联反应时间、固化温度和固化时间等因素对富氧膜性能的影响,确定了最佳富氧性能膜的制备条件:原料配比4.3,反应时间2.15h,固化温度86.25℃,固化时间1.75h;获得了富氧浓度为28.68%,透气量为4696.33 barrer的富氧膜,该膜的富氧浓度与常规商品化膜相当,透气量为常规商品化膜的2~4倍,有应用于发动机富氧进气系统的前景。通过扫描电镜检测、机械性能检测等手段对复合膜进行了进一步表征。     

Signal transformation and interpolation based on modified DCT synthesis

This paper proposes a novel signal transformation and interpolation approach based on the modification of DCT (Discrete Cosine Transform). The proposed algorithm can be applied to any periodic or quasi periodic waveform for time scale and/or pitch modification purposes in addition to signal reconstruction, compression, coding and packet lost concealment. The proposed algorithm has two advantages:

• (i) 

  Since DCT does not have the explicit phase information, one does not need the cubic spline interpolation of the phase component of the sinusoidal model.

• (ii) 

  The parameters to be interpolated can be reduced because of the energy packing efficiency of the DCT. This is particularly important if signal synthesis is carried out on a remote location from the transmitted parameters.

The results are presented on periodic waveforms and on speech signal in order to appreciate the fidelity of the proposed algorithm. In addition, the proposed method is compared with TD-PSOLA, sinusoidal model and phase vocoder algorithms. The results are presented in objective PESQ scores for time scale modification and output files are provided as supplementary material,¹ for subjective evaluation, for packet lost concealment. Results prove that the proposed modification of the DCT synthesis provides a favorable algorithm for specialists working in the signal processing area.     

基于三维分割的图像加密算法

为了实现图像安全、快速加密,设计了一种新的数字图像混沌加密算法.仿真结果表明,该算法在没有扩散函数的情况下也能很好地改变图像的直方图,可以有效地抵制已知(选择)明文攻击,而且只有1次左映射或者右映射的情况下,该方法具有高置乱程度、良好的扩散性能和足够大的密钥空间,可获得足够高的安全性.     

Vic-dioximes: A new class of sensitive materials for chemical gas sensing

Vic-dioximes, a class of organic chemical compounds, are proposed and characterized for the first time as sensitive materials for volatile organic compound sensing with sorption based chemical gas sensors. Their peculiar sensing properties described in this work originate in the oxime functional group which is a powerful H bond donor interacting strongly but reversibly with H bond acceptors. These specific interactions result in a high preferential enrichment of analyte molecules with H bonding acceptor capabilities in the sensitive material. Accordingly, sensitivity and selectivity for these compounds of vic-dioxime based sensors are high. The advantageous sensing properties are demonstrated in this work with quartz crystal microbalance sensors using 11 selected volatile organic compounds and a set of vic-dioximes varied in their substituents. Vic-dioximes with short alkylthiol substituents were found highly sensitive to such H bond acceptors as organic amines, alcohols, and esters with partition coefficients up to 26,000. At the same time they showed low affinity for aromatic compounds and chlorocarbons. Vic-dioximes are considered powerful sensing materials and interesting for practical use in chemical gas sensor arrays.     

Novel e-nose for the discrimination of volatile organic biomarkers with an array of carbon nanotubes (CNT) conductive polymer nanocomposites (CPC) sensors

We report the original design of a new type of electronic nose (e-nose) consisting of only five sensors made of hierarchically structured conductive polymer nanocomposites (CPC). Each sensor benefits from both the exceptional electrical properties of carbon nanotubes (CNT) used to build the conductive architecture and the spray layer by layer (sLbL) assembly technique, which provides the transducers with a highly specific 3D surface structure. Excellent sensitivity and selectivity were obtained by optimizing the amount of CNT with five different polymer matrices: poly(caprolactone) (PCL), poly(lactic acid) (PLA), poly(carbonate) (PC), poly(methyl methacrylate) (PMMA) and a biobased polyester (BPR). The ability of the resulting e-nose to detect nine organic solvent vapours (isopropanol, tetrahydrofuran, dichloromethane, n-heptane, cyclohexane, methanol, ethanol, water and toluene), as well as biomarkers for lung cancer detection in breath analysis, has been demonstrated. Principal component analysis (PCA) proved to be an excellent pattern recognition tool to separate vapour clusters.     

偏序时态XML索引TempPartialIndex

时态数据管理是常规数据管理的深化和扩展,具有理论研究的意义与实践应用的价值.时态数据索引是时态数据管理的重要技术支撑,是其中的一个研究热点.首先,提出了一种时态数据结构,通过数据节点间的偏序关系,可将常规的二维时间区间的处理转化为基于偏序的时态等价类上的一维的处理,该数据结构可以快速有效地处理时态操作;其次,在该新型时态数据结构基础上研究了时态XML索引TempPartialIndex,其基本特征是将时态数据结构整合到非时态的XML索引中,即,将其整合到语义层之中,通过时态过滤和语义过滤掉大量节点之后,再进行结构连接;另外,着重讨论了基于TempPartialIndex“一次一集合”及其时态变量查询和增量式的动态更新机制.同时,仿真结果表明：TempPartialIndex能够有效地支持时态XML的各类查询及更新操作,技术上具有可行性和有效性.