自动粘度仪与手动粘度仪在油品分析中的应用比较

介绍了CAV2000A动粘度仪的工作原理及测定方法,利用CAV2000自动粘度仪对润滑油、柴油、燃料油等石油产品进行运动粘度的测定,并将测定结果与现行粘度测试标准（GB／T265—1988、GB／T11137-1989）进行比较,结果表明,CAV2000自动粘度仪操作简便快速,重复性好,精度在标准方法允许的误差范围内。     

基于小波的信号去噪分析

由实际应用可得,作为一种新的多辨认分析方法的小波变换,由于具有多分辨特征和时频局部性,可同时进行频域和时域分析,所以特别适用于进行非平稳信号的处理。首先介绍了小波分析的信号去噪原理,其次接着阐述了4种去噪算法：小波分解与重构去噪方法、模极大值检测法、阈值法及平移不变量小波去噪法。对于叠加了高斯白噪声的仿真信号,分别将上述的4种方法用于去噪处理,并通过仿真过程不同及图形差异对几种方法进行比较。     

Two‐phase flow behavior in microtube reactors during biodiesel production from waste cooking oil

Flow patterns in the course of transesterification of waste cooking oil (WCO), sunflower oil (SFO) with water and/or oleic acid as a model of WCO, and pure SFO in the presence of a KOH catalyst in microtubes were investigated. FAME yield for the transesterification of WCO reached more than 89% in the microtube reactors with a residence time of 252 s at 333 K. The flow patterns when using WCO were changed from a liquid–liquid slug flow at the inlet region to a parallel flow at the middle region, and then to a homogeneous liquid flow at the outlet region as the reaction proceeded at 333 K. Fine droplets containing glycerol and methanol generally formed in oil slugs when using pure SFO, but were almost unobservable when using WCO. The soap produced from free fatty acids was considered to be the main factor affecting the flow patterns of WCO and SFO. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Enhancement of Polyunsaturated Fatty Acid Production by Selenium Treatment in Polyunsaturated Fatty Acid-Producing Fungus

The effect of selenium (Se) treatment on the content of intracellular polyunsaturated fatty acids (PUFA) was investigated. Selenium treatment could effectively increase the yields of arachidonic acid (AA) and linoleic acid (LA). When AA-producing Diasporangium jonesianum recombinant strain D-A1 was cultured in a medium containing 90 μg mL⁻¹ Se, the growth of D. jonesianum recombinant strain D-A1 was constrained, but the content of AA in the total fatty acids reached 9.3%, 1.7-fold higher than the control. The content of LA was also increased from 25.9 to 37.7%. Under various culture conditions, Se treatment (90 μg mL⁻¹) was generally beneficial to the yields of LA and AA. However, there was no significant increase in the contents of eicosapentaenoic acid (EPA) and γ-linolenic acid. Therefore, the use of Se is advantageous for regulating the content of intracellular PUFA in D. jonesianum recombinant strain D-A1, and could be good enhancer in the yields of AA and LA.     

A novel contention solution strategy based on priority for optical burst switching networks

A fundamental issue in optical burst switching (OBS) networks is to solve the burst contention for the core node. In this paper, a novel priority-based contention solution strategy for OBS networks is proposed. When the contention occurs, the burst priority is considered firstly, and then the burst segmentation method is used for the low priority bursts in this strategy. Ensuring the integrity of high priority bursts, part of the segmented bursts can be transmitted to the destination node via combining wavelength conversion and optical buffer method. Simulation results show that the proposed scheme not only ensures the integrity of high priority bursts, but also reduces the packet loss rate of the low priority bursts maximally, so that it can support good quality of service (QoS) for the network.     

电信套餐资费策略演进分析

资费作为业务的重要组成部分,其策略制定与电信企业的总体业务发展战略密切相关,也深受政府电信资费政策改革的影响。本文首先从全球电信资费的改革历程入手,详细解读了我国电信管制政策及电信资费发展趋势。其次,选取了北京联通及各运营商有代表性的3类产品资费策略进行详细分析,对运营商之间的资费策略进行了比较,深刻揭示了电信运营商的资费策略演进路线,在全业务竞争时代,运营商的资费策略已经由单纯降价逐渐演变为全业务深度渗透捆绑,同时指出了针对不同微分市场开展全业务资费策略设计的关键所在。     

Synthesis and characterization of photoactive poly(arylene ether sulfone)s containing azobenzene moieties in their main chains

A series of azobenzene functionalized poly(arylene ether sulfone)s (azo-PAESs) has been synthesized via nucleophilic aromatic substitution polycondensation, and azobenzene chromophores could be introduced into the polymer main chains by copolymerization from azo-monomers. These main chain type azo-PAESs have high glass transition temperatures and good thermal stability. Exposed to an interference pattern laser beam, spin-coated films of the azo-PAESs can form clear and stable surface relief gratings (SRGs). These SRGs show increased thermal stabilities with the content of azo moieties and cannot be fully removed until the temperature increases to 300 °C for azo-PAESs with a content of azo segments above 50%.     

Two cobalt(II) coordination polymers based on carboxylate ligand: Preparation,crystal structures and magnetic properties

Two new coordination polymers, [Co₂(L)_1.5(OH)(H₂O)₂]·2H₂O (1) and [CoL(bpp)] (2) (H₂L = 2,5-dibenzoylterephthalic acid and bpp = 1,3-bis(4-pyridyl)propane), have been synthesized and characterized by elemental analyses, IR spectra, and thermogravimetric analyses. Their structures were determined by single crystal X-ray diffraction analyses. Complex 1 exhibits a 3D framework assembled from tetra-nuclear cobalt-oxygen bridged by carboxylic O atoms with a (4¹²·6³) topology. Complex 2 possesses a 2D layered structure which extends into a 3D architecture via C–H···π interaction between propane proton and the phenyl ring or pyridine ring of an adjacent sheets. Furthermore, the magnetic properties of them are discussed.     

The promotional effect of Cr on catalytic activity of Pt/ZSM-35 for H2-SCR in excess oxygen

Selective catalytic reduction of NO by hydrogen was studied over Cr modified Pt/ZSM-35 catalysts. The preparation process greatly influenced catalytic activity and sample prepared by co-impregnation method exhibits the best activity. In situ DRIFT studies revealed that on Pt–Cr/ZSM-35, (1) new Pt-NO^δ+ and NO species adsorbed on Pt were detected upon NO + O₂ adsorption; (2) much more ammonia species were formed under reaction condition. Cr addition not only enhanced the adsorption of NO_x but also promoted the formation of surface NH₄⁺ species, which should be the origin of promotional effect of Cr on Pt/ZSM-35 for H₂-SCR reaction.     

铁路客运站与城市轨道交通换乘衔接组织研究

本文在铁路客运站与城市轨道交通站点换乘衔接组织机理分析的基础上,根据城市轨道交通站点与铁路客运站之间的空间关系,总结出五种轨道交通与铁路客运站的站点布局衔接模式。以轨道交通站点服务的乘客总换乘时间最小为目标建立最优化函数,结合算例用单纯形法求出每个时间段内轨道交通的发车间隔和发车时间,为轨道交通的衔接规划和运营管理提供参考。