Note: Electrical and thermal characterization of a ferroelectric thin film with an electro-thermal nanoprobe

The localized temperature-dependent piezoelectric response of ferroelectric barium strontium titanate (BST) thin films is studied using an electro-thermal (ET) nanoprobe. The ET probe provides independent electrical and thermal excitation to a nanometer-scale volume of the specimen and is capable of detecting the phase transition temperature of the BST thin films. The piezoresponse measured by the ET probe follows the temperature dependence of the piezoelectric constant, whereas with bulk heating the response follows the temperature dependence of the spontaneous polarization. The observed differences stem from the localized inhomogeneous electro-thermal field distribution at the specimen.     

大型密封法兰弯曲成形工艺研究

提出了一种大型密封法兰成形新工艺，包括分段弯曲、现场组焊、现场精加工。新工艺免去了大型立车的粗加工，取而代之的是分段弯曲成形工艺，最后在施工现场进行组焊并采用多功能机床进行精加工。通过小型模拟件的实验与数值模拟研究，分析了L形非对称截面法兰弯曲成形过程中工件的变形规律，以及弯曲成形后工件的截面形状变化和侧弯情况，并采用L形非对称截面法兰成对弯曲的方法，使其截面形式成为对称结构，从而有效地解决了非对称截面法兰单件弯曲存在的侧弯缺陷。采用新工艺制造了某风洞工程上直径为8．5m的大型密封法兰，实践表明，采用新工艺成形大型法兰是完全可行的，其加工制造精度完全满足设计要求。由于新工艺不需立车，为特大直径法兰的制造开辟了新途径。     

六自由度工业机器人手腕分析与优化综合

本文分析了用于六自由度工业机器人的球型手腕, 这种手腕具有结构紧凑, 姿态范围大, 定位精度高等特点.在运动学分析的基础上, 研究了手腕定位精度与各关节参数精度误差之间的关系, 给出了完整的误差数学模型, 借助于此模型通过优化设计, 得到了各关节参数精度的合理分配, 为机器人机械结构及控制系统的精度设计提供了依据.文章阐述了使机器人实现快速响应, 提高定位精度的优化设计方法.     

Atomically Thin Defect‐Rich Fe–Mn–O Hybrid Nanosheets as High Efficient Electrocatalyst for Water Oxidation

Engineering non‐noble metal–based electrocatalysts with superior water oxidation performance is highly desirable for the production of renewable chemical fuels. Here, an atomically thin low‐crystallinity Fe–Mn–O hybrid nanosheet grown on carbon cloth (Fe–Mn–O NS/CC) is successfully synthetized as an efficient oxygen evolution reaction (OER) catalyst. The synthesis strategy involves a facile reflux reaction and subsequent low‐temperature calcination process, and the morphology and composition of hybrid nanosheets can be tailored conveniently. The defect‐rich Fe–Mn–O ultrathin nanosheet with uniform element distribution enables exposure of more catalytic active sites; moreover, the atomic‐scale synergistic action of Mn and Fe oxide contributes to an enhanced intrinsic catalytic activity. Therefore, the optimized Fe–Mn–O hybrid nanosheets, with lateral sizes of about 100–600 nm and ≈1.4 nm in thickness, enable a low onset potential of 1.46 V, low overpotential of 273 mV for current density of 10 mA cm^?2, a small Tafel slope of 63.9 mV dec^?1, and superior durability, which are superior to that of individual MnO₂ and FeOOH electrode, and even outperforming most reported MnO₂‐based electrocatalysts.     

氧化锅生产锑白过程中去除油状氧化渣研究及应用

介绍了恒邦股份公司采用火法锑氧化锅氧化吹炼生产锑白产品,氧化锅生产过程中,因氧化锅熔液表面容易产生一种黑油状氧化渣,俗称“黑油”,覆盖在熔液表面,因没有较为实用的方法用于黑油的除去,不仅增加了员工劳动强度,而且因去除不及时,严重影响了氧化锅吹炼表面积,影响了氧化锅生产效率及锑白产品质量;针对此问题,通过实验研究,最终提出采用试剂硼砂能及时有效的对氧化锅表面黑油渣进行粘附去除,该方法存在操作简单、粘附黑油渣能力强、效率高、没有二次污染等有点,具有较高的应用推广价值。     

金属矿山岩体移动监测数据库系统设计与实现

介绍了在微机上建立金属矿山岩移监测数据库系统,本系统利用ＦＯＸＢＡＳＥＴＲＵＥ ＢＡＳＩＣ混合编程,具有对监测数据进行数据管理,数据处理以及绘图等功能,并在某矿山的岩移监测研究中得到应用,效果良好。     

Cytotoxicity of murine B lymphocytes induced by human VH4-34 (VH4.21) gene-encoded monoclonal antibodies

We previously found that a ventricular isovolumic pressure-time curve could be well fitted by the difference between two S-shaped logistic curves for the pressure rising and falling components, and called it "hybrid logistic" function: P(t)=A/[1+exp[-(4B/A)(t-C)]]-D/[1+exp[-(4E/D)(t-F)]]+G. We reported that the parameters of this hybrid logistic function are useful to characterize left ventricular contraction and relaxation comprehensively. In this study, we investigated how well this hybrid logistic function could fit the isometric twitch force-time curves of cross-circulated right ventricular papillary muscles of 7 dogs. This function precisely fitted the isometric force curves with correlation coefficients above 0.9996, much better than another fitting function (F(t)=C(t/A)(B)exp[1-(t/A)(B)]) proposed by Nwasokwa. The present results indicate that our hybrid logistic function can also reasonably express the canine right ventricular papillary muscle isometric twitch force-time curve. We suggest the possibility that the parameters of this hybrid logistic function are also useful to comprehensively characterize right ventricular papillary muscle twitch contraction and relaxation.     

Rear‐Passivated Ultrathin Cu(In,Ga)Se2 Films by Al2O3 Nanostructures Using Glancing Angle Deposition Toward Photovoltaic Devices with Enhanced Efficiency

In this work, for the first time, the addition of aluminum oxide nanostructures (Al₂O₃ NSs) grown by glancing angle deposition (GLAD) is investigated on an ultrathin Cu(In,Ga)Se₂ device (400 nm) fabricated using a sequential process, i.e., post‐selenization of the metallic precursor layer. The most striking observation to emerge from this study is the alleviation of phase separation after adding the Al₂O₃ NSs with improved Se diffusion into the non‐uniformed metallic precursor due to the surface roughness resulting from the Al₂O₃ NSs. In addition, the raised Na concentration at the rear surface can be attributed to the increased diffusion of Na ion facilitated by Al₂O₃ NSs. The coverage and thickness of the Al₂O₃ NSs significantly affects the cell performance because of an increase in shunt resistance associated with the formation of Na₂Se_X and phase separation. The passivation effect attributed to the Al₂O₃ NSs is well studied using the bias‐EQE measurement and J–V characteristics under dark and illuminated conditions. With the optimization of the Al₂O₃ NSs, the remarkable enhancement in the cell performance occurs, exhibiting a power conversion efficiency increase from 2.83% to 5.33%, demonstrating a promising method for improving ultrathin Cu(In,Ga)Se₂ devices, and providing significant opportunities for further applications.     

冷冻煅烧法制备NiO/Ni复合材料及电容性能研究

首次采用冷冻煅烧法制备NiO/Ni纳米复合材料,重点考察不同冷冻温度对该复合材料的结构形貌及电容性能的影响。结果表明:随着冷冻温度的降低,结晶过冷度增大,材料的粒径不断减小并且趋于均匀化,比表面积单调增大。当冷冻温度为-20℃时,材料平均粒径为20~50 nm,比表面积达到337.6 m^2/g。同时,纳米Ni单质的引入也增强了材料的导电性能,当电流密度为1 A/g时,其比电容达到820 F/g,所制得NiO/Ni纳米复合材料具有优异的电化学性能。该方法大大降低了材料制备的能耗,为NiO/Ni纳米复合材料的制备方法提供新的思路。     

Practical evaluation of encrypted traffic classification based on a combined method of entropy estimation and neural networks

Encrypted traffic classification plays a vital role in cybersecurity as network traffic encryption becomes prevalent. First, we briefly introduce three traffic encryption mechanisms: IPsec, SSL/TLS, and SRTP. After evaluating the performances of support vector machine, random forest, naïve Bayes, and logistic regression for traffic classification, we propose the combined approach of entropy estimation and artificial neural networks. First, network traffic is classified as encrypted or plaintext with entropy estimation. Encrypted traffic is then further classified using neural networks. We propose using traffic packet’s sizes, packet's inter‐arrival time, and direction as the neural network's input. Our combined approach was evaluated with the dataset obtained from the Canadian Institute for Cybersecurity. Results show an improved precision (from 1 to 7 percentage points), and some application classification metrics improved nearly by 30 percentage points.