基于多线程评估的基因表达式编程算法

分析了基因表达式编程(GEP)算法的性能关键,指出提升的一个重要瓶颈是在个体评估阶段;结合多核CPU并行计算能力,提出了基于多线程评估的GEP算法(MTEGEP),并通过实验验证了MTEGEP的高效性：在双核CPU环境下MTEGEP运算速度是传统GEP的1.89倍,而在8核CPU环境下达到了6.48倍。实验结果表明该算法能有效提升GEP算法的性能。     

Investigation on the design and synthesis of new systems of BNT-based lead-free piezoelectric ceramics

Three primary differences between BNT- and PZT-based ceramics were analyzed from the composition and the active component of the materials. Based on the analysis the authors’ group developed the new idea of the design of the multiple complex in the A-site ions of BNT compounds. (Bi_0.5Na_0.5)²⁺, Bi³⁺ and Na⁺ in the ABO₃ structure are defined as A-site, A₁-site and A₂-site ions, respectively, and A, A₁ and A₂-site ions can be simultaneously or singly substituted partially by alkaline-earth metal ions, metal ions with +3 valence and metal ions with +1 valence, respectively. Under this consideration, Several new systems of Bi_0.5Na_0.5TiO₃ (abbreviated as BNT)-based lead-free piezoelectric ceramics were proposed. These ceramics can be prepared by conventional ceramic techniques and have excellent piezoelectric performance. Among these materials, Bi_0.5(Na_1−x−y K _x Li _y )_0.5TiO₃ possesses higher piezoelectric constant (d ₃₃ = 230 pC/N), higher electromechanical couple factor (k _p = 0.40), larger remanent polarization (P _r = 38.9 μC/cm²) and a better P-E hysteresis loop until about 200^∘C. This work was supported by the projects of NSFC (50410179), (50572066), and (59972020), and NAMMC (2001-AA325060).     

Multistep impregnation method for incorporation of high amount of titania into SBA-15

A multistep impregnation method was employed to incorporate high amount of titania into the mesoporous SBA-15 silica. No damage to the SBA-15 silica mesostructures was caused by the loading of titania in every cycle. The existence of titania small nanodomains were confirmed to be present by Raman spectra and UV–vis DRS measurements. High dispersion of them was realized via this method according to the results of low-angle X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and N₂ sorption measurements. Importantly, no blockage of mesostructures was acknowledged with titania content up to 24.4 wt.%. In comparison, normally used one-step impregnation method led to serious blockage of mesopores as the results of formation of bulk titania particles in the mesochannels. Photo-activity test for the removal of oestrogen showed the superiority of the materials synthesized by multistep impregnation method to one-step impregnation method.     

Semiconductor/porous silica glass nanocomposites via the single-source precursor approach

The utilization of single-source molecular precursor approach to obtain II–VI and IV–VI semiconductors encapsulated in porous Vycor glass (PVG) is described. The procedure is based on the impregnation of cadmium and lead(II) diethyl-dithiocarbamate complexes, Cd(S₂CNEt₂)₂ and Pb(S₂CNEt₂)₂, inside the porous environment of PVG followed by a thermal treatment of the glass. The pyrolysis of the impregnated precursor gives rise to binary semiconductors CdS and PbS, respectively. The impregnation step is driven by interactions between the precursors and active sites located at glass pore surfaces. After completing the impregnation–decomposition cycle, it was found that the active glass sites were regenerated, making new cycles possible. The amount of encapsulated semiconductor increases linearly as a function of the number of cycles. Nanocomposites obtained after 1–10 cycles were prepared and characterized by optical spectroscopy, X-ray diffraction powder and transmission electron microscopy.     

Formation of lanthanum beryllate real structure under different crystallization conditions

The aim of this paper is to characterize the major structural defects of lanthanum beryllate single crystals grown by the Czochralski method, including those doped with rare-earth elements, and to reveal their relationship to specific properties of the crystal structure of La₂Be₂O₅ and with their crystallization conditions. As a basic method for research, we used transmission X-ray topography. It was established that the defect state of La₂Be₂O₅ crystals prepared by this method can be caused by different types of dislocations and their ordered assemblies, solid-phase inclusions of crucible metal and eutectically co-crystallizing phases, as well as by face growth sectors with elevated content of dopant. We show a possibility for growing single crystals of doped lanthanum beryllate having a minimum quantity of structural defects that could be suitable for manufacture of high quality laser rods.     

Lithium solubility limit in ZnGa2O4:Bi0.0013+,Li+ phosphor

The lithium solubility limit, photoluminescence (PL) and photoluminescence excitation (PLE) properties of lithium ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor have been investigated. A LiGaO₂ second phase began to appear from 3 mol% Li⁺ ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor. The enhanced brightness of blue (λ_ex = 254 nm) and white (λ_ex = 315 nm) colors of bismuth ions doped ZnGa₂O₄:Bi³⁺,Li⁺ phosphor was assigned to the formation of LiGaO₂. Bi³⁺ activated lithium zinc gallate phosphor showed a more enhanced PLE peak around 315 nm than that of lithium zinc gallate phosphor when λ_em = 520 nm. Thus, we observed that the PL intensity of ZnGa₂O₄:Bi³⁺,Li⁺ phosphor with λ_em = 520 nm was much greater than that of ZnGa₂O₄:Li⁺ phosphor. Also, ZnGa₂O₄:Bi³⁺,Li⁺ phosphor exhibited a shorter decay time than that of ZnGa₂O₄:Li⁺ phosphor by about a factor of about 2.     

自组织模式识别与经济预测

基于自组织数据挖掘方法与经济预测原则,提出了自组织模式识别方法。该方法的主要特点是在几个相似模式的合成中使用了数据分组处理方法自动合成技术,实际应用于经济预测时比传统意义上的预测方法方便。实例表明了它在经济预测中的有效性。同时,使用增加同类经济对象样本数据的方法,解决了样本数据不足的问题。     

有限域FP上的DFT在秘密共享中的应用

为了提高Shamir (m,n)门限方案中的n个共享的生成速度和m个共享者恢复密钥的运算速度,将Shamir (m,n)门限方案中采用拉格朗日插值法生成n个共享和m个共享者恢复密钥的方法,改为利用有限域上的离散傅里叶变换(DFT)来实现。由于有限域上的DFT也具循环卷积性和类似复数域上FFT的快速算法,从而可以提高n个共享的生成速度。当m >[n/2]时,能够提高可信中心构作n个共享的运算速度,特别当门限数m与共享数n相等且为2的方幂时,还能够提高共享者恢复密钥的运算速度。     

脱碳处理对Pt/WC复合材料催化性能的影响

采用溶胶-凝胶法,以钨酸钠为钨源、酚醛树脂为碳源合成碳化钨前驱体干凝胶,经原位碳化制备纳米碳化钨（WC）粉体,纳米WC粉体中的玻璃碳采用浓硝酸浸渍法脱除。在纳米WC粉料浆中以甲醛（HCHO）作为氯铂酸（H2PtCl6·6H2O）的还原剂,室温合成得到Pt/WC复合催化剂材料;以XRD、SEM、EDS等测试方法对样品的理化特性进行表征,并在酸性介质中采用循环伏安法测试材料的电化学催化活性。结果表明：相较于未经过脱碳处理的WC,经过浓硝酸脱碳处理后的Pt/WC电极催化材料的催化活性更好。经溶胶-凝胶法及原位碳化制备的纳米WC的颗粒径为20-80纳米,其本身具备较好的电催化活性。样品中残留的玻璃碳对WC具有包覆作用,会降低WC的电催化活性。采取浓硝酸脱碳的方式可有效脱除纳米WC粉体中的玻璃碳,发挥WC材料作为电极催化材料的电催化活性。     

Effects of Hydrogen Ion Implantation on TiCC Coating of Stainless Steel

Titanium carbide coatings are widely used as various wearresistant material. The hydrogen erosion resistance of TiCC films and the effect of hydrogen participation on TiCC films were studied. Seventyfive percent TiCC films are prepared on stainless steel surface by using ion mixing, where TiCC films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 12×10-3 Pa. Characterization for the 75% TiCC films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy (SIMS) was used to analyze hydrogen concentration variation with depth, XRay diffraction (XRD) was used to identify the phases, and Auger electron spectra (AES) as well as Xray photoelectron spectra (XPS) were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiCC films. It is found that TiCC films on stainless steel surface can prevent hydrogen from entering stainless steel.