无孔转鼓螺旋离心机抱死事故原因分析与改造

简要介绍了用于三聚氰胺精制的无孔转鼓螺旋离心机的结构,分析了其内、外轴承法兰抱死的原因并采取了相应的修复及改造措施。无孔转鼓螺旋离心机检修完成后重新投入生产,至今未出现类似事故。     

胜利油田沾3区块油藏中Geobacillus菌的激活研究

利用16S rRNA克隆文库技术分析胜利油田沾3区块油藏样品的微生物群落结构,使用不同激活剂对沾3区块油藏样品进行内源微生物激活,对激活后样品进行乳化能力、产生表面活性物质能力评价及微生物群落结构分析,并开展物理模拟驱油实验。结果表明:沾3区块油藏样品中含有2%的Geobacillus,该菌是沾3区块油藏内源微生物中产生表面活性物质、发挥乳化功能的关键菌群;加入适宜的激活剂体系可以选择性激活该类细菌,使其成为优势菌;利用选择性激活Geobacillus的配方激活沾3区块油藏内源微生物,可以在水驱基础上提高原油采收率10.8%。     

原位十字板试验测得的软粘土灵敏度

收集了国内两个地区(上海和杭州湾)以及美国和日本一些地区软粘土的勘察数据,对原位十字板试验(FVT)和无侧限抗压强度试验(UCT)这两种试验所测得的灵敏度和强度进行了详细的对比与分析,并对重塑方式的影响进行了研究.发现这些地区普遍存在FVT试验得到的灵敏度要明显小于UCT试验结果,会严重低估软粘土的灵敏度;而原状土强度和重塑土强度均要大于UCT试验结果,重塑土强度尤其明显.其中重塑方式是一个重要影响因素.研究还发现FVT试验得到的重塑土强度、灵敏度与土的液性指数的相关性随着液性指数的增大而明显变差,与一些广泛使用的经验关系也差别较大.这些结果应该引起工程界的重视.     

Enhancing <Emphasis Type="SmallCaps">l</Emphasis>-Lysine Production of Beet Molasses by Engineered <Emphasis Type="Italic">Escherichia coli</Emphasis> Using an In Situ Pretreatment Method

Reducing the viscosity of molasses environmentally and selectively removing the harmful ingredients for microbes are the keys to promoting the bioavailability of molasses. A simple and environmental in situ pretreatment method integrating surfactants and alkali was developed to reduce the viscosity of molasses prior to l-lysine production using Escherichia coli ZY0217. Adding activated carbon and modified orange peel based on the in situ pretreatment process effectively removed pigments and excessive zinc in the molasses and also significantly increased the cell growth and l-lysine yield from E. coli ZY0217. The experimental results showed that a mixture of secondary alkane sulfonate, an anionic surfactant, and HodagCB-6, a non-ionic surfactant, effectively reduced the viscosity of the molasses more so than any single surfactant. When the surfactant mixture was added at a concentration of 0.04 g/L to the molasses, the ω value was 0.4, and when ammonia was added at 0.6 %, the lowest viscosity of 705 mPa?·?s was obtained. Further, 91.5 % of the color and 86.68 % of the original levels of zinc were removed using an activated carbon and modified orange peel treatment on the molasses with the lowest viscosity, which further promoted cell growth and l-lysine production. In the fed-batch cultivation process, the l-lysine concentration achieved using a constant-speed feeding strategy was 45.89 g/L, with an l-lysine yield of 27.18 %, whereas the l-lysine yield from untreated molasses was only 10.13 %. The increase in l-lysine yield was related to the reduced viscosity and the detoxification of the molasses. Lastly, the pretreatment was found to significantly enhance the conversion of sugars in the molasses to l-lysine.     

Progress of pyrene-based organic semiconductor in organic field effect transistors

Thanks to the pure blue emitting, high planarity, electron rich and ease of chemical modification, pyrene has been thoroughly investigated for applications in organic electronics such as organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic solar cells (OSCs). Especially, great progresses have been made of pyrene-based organic semiconductors for OFETs in past decades. Due to the difference of molecular structure, pyrene-based organic semiconductors are divided into three categories, pyrene as terminal group, pyrene as center core and fused pyrene derivatives. This minireview gives a brief introduction of the structure-property relationship and application in OFETs about most of pyrene-based semiconducting materials since 2006, illustrating that pyrene is a good building block to construct semiconductors with superior transport property for OFETs. Finally, we provide a summary concerning the methodology to improve the transport property of the pyrene-based semiconducting materials as well as an outlook.     

基于Android平台的一种保护隐私的即时通讯工具的设计与实现

在移动互联网飞速发展的今天,即时通讯工具已经成为人们生活和工作中不可或缺的工具。但是,国内外主流的即时通讯工具依然面临着两大主要问题。一个是基于不同协议的软件的互联互通问题,另一个是日益严峻的即时通讯的安全性与隐私性问题。为了从根本上解决问题,针对即时通讯工具的特点进行了深入分析,最终设计并实现了一款基于安卓平台上更具安全性、更实用、用户体验更好的即时通讯工具SecretChat。本工具采用开放的XMPP通讯协议,并在XMPP上实现OTR安全协议。经过系统测试,系统具备稳定性并且具有良好的互联互通性能和隐私保护功能。     

PSO优化LS-SVM在模拟电路故障预测中的应用

针对模拟电路故障预测的特点,提出一种基于PSO优化LS-SVM惩罚因子和核参数的模拟电路故障预测方法。利用小波包分解重构构造能量特征向量,通过计算PPMCC和欧氏距离来表征电路中元件的健康程度,定义为健康度,由此推导出电路发生故障时该元件的故障阈值。应用PSO优化的LS-SVM模型来实现模拟电路的故障预测,预测各个时间点的健康度变化轨迹并估计模拟电路的剩余寿命。通过仿真实验得知,该方法简单便捷,能够有效实现模拟电路的故障预测,具有较好的实用性。     

一类实奇芽等价的充要条件

给定一自反的Ｂａｎａｃｈ空间Ｘ．在ｃ^∞函数芽环∈（Ｘ）中,任何在原点Ｏ∈Ｘ的实奇芽ｆ,若其二阶Ｆｒｅｃｈｅｔ导数ｆ″（０）＝Ｔ是一个Ｆｒｅｄｈｏｌｍ算子,则它同构于形如：1/2+g(v)的一个芽．如果代替ｇ以一个与之同构的芽ｇ_１,显然得到一个与原来的芽同构的芽．然而,其逆是否真呢？本文将证明其逆命题亦真     

集成Multisim电路仿真功能到LabVIEW的应用研究

为了更有效地在某装备随动测试系统中进行故障诊断仿真,详细介绍了应用LabVIEW中的Multisim tool工具包,从而有效地把Multisim tools的电路仿真功能集成到LabVIEW并和其虚拟仪器的功能结合到一起,且已经取得了良好的诊断效果。     

Self-Lubricating Ultrahigh Molecular Weight Polyethylene Thin Films with Excellent Wear Resistance at Light Friction Loads on Glass and Silicon

Thin films of ultrahigh molecular weight polyethylene (UHMWPE) were prepared on glass and silicon using a dip-coating technique, followed by removal of the decahydronaphthalene solvent at 140?°C for 20?hours and cooling in the oven in air. The wetting ability of the films was investigated by a contact angle method. The tribological behavior of the films was investigated using a ball-on-disk configuration in reciprocating mode. The reciprocating frequency of 4?Hz and single sliding distance of 5?mm used corresponded to a sliding speed of 40?mm/s. The counterface was a GCr15 steel ball with diameter of 3?mm and the normal frictional loads were 10–300?g. The worn surfaces on the films and wear scars on the steel ball were observed and analyzed by scanning electron microscopy (SEM). It was found that the surface morphologies of the films on glass and silicon were different, which is ascribed to the difference in thermal conductivity of the glass and silicon. Evaporation of the solution caused micro-orifices in the films on glass. The water contacting angle of about 87° on the films on the two substrates was similar to that of bulk UHMWPE. Their friction coefficient of about 0.1–0.2 indicated the films were self-lubricating. The wear life of the films decreased quickly with the increase of friction load. At light friction loads, the films showed excellent wear resistance. Extrusion was believed to be the main wear mechanism of the films.