敷设吸声尖劈的声纳平台水下声学特性试验研究

基于模型试验开展了敷设吸声尖劈的声纳平台水下声学特性研究,讨论了尖劈不同敷设方式下声纳平台的声场分布,分析了声波入射角度对声纳平台声场的影响.分析了声纳平台0%,36%,60%和100%敷设吸声尖劈,声波在0°方向和90°方向入射声纳平台的情况,以及尖劈不同敷设方式、声波不同入射角度时声纳平台的声场分布.研究表明:声纳平台内部各点声压不尽相同;随尖劈敷设密度的增加,声纳平台自噪声在降低,各水听器声压的差异在逐渐加大;吸声尖劈可改变声纳平台的声场,降低声纳平台的自噪声,但存在"声泄漏"现象;声波入射方向对声纳平台声场也有一定影响,但位置不同、声波频率不同,其影响也各有差异.     

用于品质动力学仿真的悬架非线性承载模型

针对传统的悬架非线性承载特性模型的卸载边界不一致及加载和卸载切换时承载特性的过渡曲线不一致影响悬架非线性承载特性的精确模拟等问题,在Fancher模型基础上,提出了基于悬架变形转折点的卸载边界修正算法及过渡曲线修正算法,通过卸载边界修正算法,实现了对悬架系统非线性承载特性中卸栽边界不一致现象的描述,通过过渡曲线修正算法...     

Synthesis of novel active ester ether resin and its effects on positive thermal CTP plates

A novel active ester ether resin, consisting of p-hydroxyphenylacetic acid and a mixed-phenol novolac resin, was produced by the addition of ethyl vinyl ether to a carbonyl novolac resin. This study investigated the conditions of its synthesis and characterized its structure using infrared and 1 H NMR spectroscopies, and gel-permeation chromatography. Its solubility in alkaline solution differed greatly before and after decomposition. The results of thermal gravimetric analysis confirmed the formation of an active ester ether resin of p-hydroxyphenylacetic acid and novolac resin. The resin had acidolysis activity at room temperature and pyrolysis activity at high temperatures (140-200°C) and could be used in the imaging layer of a positive thermal plate for computer-to-plate processes as an inhibitor/accelerator to improve its alcohol resistance, alkali resistance, sensitivity, lattice point reducibility, and developing tolerance.     

Scriptaid affects histone acetylation and the expression of development-related genes at different stages of porcine somatic cell nuclear transfer embryo during early development

Although the somatic cell nuclear transfer(SCNT) technique has been used extensively for cloning and generating transgenic pigs,the cloning efficiency is still very low.It has been proposed that the low efficiency of this technique is the result of incomplete epigenetic reprogramming and abnormal gene expression during early embryonic development.In this study,we investigate the effect of Scriptaid,a low-toxicity histone deacetylase inhibitor,on the developmental competence of porcine SCNT embryos.We found that treating SCNT embryos with 500 nmol/L Scriptaid for 15 h after activation significantly enhanced the blastocyst formation rate(27.7%) compared with the untreated group(control)(12.2%,P<0.05).Using an immunofluorescence technique to measure the average fluorescence intensity,we also found that treating SCNT embryos with Scriptaid increased the level of histone acetylation on histone H3 at lysine 14(acH3K14).Furthermore,treating embryos with Scriptaid increased the expression level of three genes that play important roles during embryonic development(Oct4,Klf4 at the blastocyst stage and Nanog at the 4-cell stage).Moreover,the expression level of the apoptosis-related gene Caspase-3 was significantly lower in the Scriptaid-treated SCNT embryos compared with the control SCNT embryos at the 4-cell and blastocyst stages.In conclusion,these results indicate that Scriptaid treatment improves the development and nuclear reprogramming of porcine SCNT embryos.     

Up-conversion luminescence of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4

The synthesis and up-conversion luminescent properties of YTaO4：Er^3＋ and YTaO4：Er^3＋/Yb^3＋ are reported for the first time. According to the measurement results of up-conversion spectra, Yb^3＋ co-doping can remarkably enhance the green （^2H11/2/^4S3/2→^4I15/2） and red （^4F9/2→^4I15/2） emissions, but depress the infrared emission （^4I9/2→^4I15/2）. With the increase of the Yb^3＋ concentration, the intensity of green emission increases, after that, when the Yb^3＋ concentration increases continuously, the intensity of green emission decreases, while those of the red and infrared emissions increase and decrease alternately. In addition, the up-conversion mechanisms of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4 are also discussed. It is found that the transform of up-conversion mechanism from two-step energy transfer to cooperating sensitization takes place when Yb^3＋ concentration is increased up to 12 mol%. With the further increase of Yb^3＋ concentration, the energy-back-transfer gradually becomes the dominant up-conversion mechanism, which results in the quenching of the green emission and slight increasing of the red and infrared emissions.     

非精确线搜索条件下共轭梯度法的收敛性分析

对Hideaki与Yasushi提出的两种使用目标函数值的共轭梯度法进行了研究,在一种新的Wolfe型线搜索条件下分析了它们的收敛性质.通过讨论可知,在其它的非精确线搜索条件下这两种共轭梯度法也是可行的.最后的数值试验表明了所给共轭梯度法的有效性.     

锌浸出渣的还原焙烧和人工硫化矿物浮选过程中硫酸铅和硫酸锌的反应行为

To evaluate the feasibility of recovering Pb and Zn sulfides and Ag-containing minerals from Zn leaching residue by the process of reduction roasting followed by flotation, the reaction behaviors of Pb and Zn sulfates during this process were investigated. Chemical analysis showed that the transformation ratios of PbSO₄ and ZnSO₄ could reach 65.51% and 52.12%, respectively, after reduction roasting, and the introduction of a sulfidation agent could improve the transformation ratios of these sulfates. scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) revealed that temperature obviously affects the particle size, crystal growth, and morphology of the artificial Pb and Zn sulfide minerals. Particle size analysis demonstrated that the particle size of the materials increases after roasting. Flotation tests revealed that a flotation concentrate composed of 12.01wt% Pb, 27.78wt% Zn, and 6.975 × 10?2wt% Ag with recoveries of 60.54%, 29.24%, and 57.64%, respectively, could be obtained after roasting.     

基于PSO-BP神经网络的探空湿度太阳辐射误差修正

采用计算流体动力学(CFD)软件仿真太阳辐射偏干误差可获得无线探空仪的湿度修正因子,提高了湿度廓线的精度,有助于提升天气预报、气候预测及气象灾害预报预警能力。但湿度修正因子存在明显的时空分布特性,采用CFD方法对每条湿度廓线进行修正计算量庞大。针对这一问题,以CFD软件仿真出典型气压、太阳辐射量和太阳高度角下的温度误差作为数据样本,通过粒子群优化(PSO)的BP神经网络构建预测模型,对探空湿度太阳辐射温度误差进行预测,并利用饱和水汽压逼近公式推算湿度测量的修正因子。研究结果表明,以南京探空站某一天的探空数据作为测试对象,CFD计算和PSO-BP预测的湿度测量太阳辐射误差吻合度较好,说明PSO-BP神经网络预测方法能够对湿度廓线的太阳辐射偏干误差进行有效修正,而且可显著提高修正效率。     

Iontronic pressure sensor with high sensitivity and linear response over a wide pressure range based on soft micropillared electrodes

Electronic skins and flexible pressure sensors are important devices for advanced healthcare and intelli-gent robotics.Sensitivity is a key parameter of flexibl...