A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation

Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.     

DGPS在可控震源施工中的应用

在可控震源施工中，采用DGPS(差分全球卫星定位系统)实施实时点位监控，对保证施工质量、提高生产效率起着积极的作用。本文主要介绍PELTON ADVANCE Ⅲ GPS系统的安装和使用情况。     

凸轮逆序测量方法

目前各杂志所发表的关于凸轮测量的文章，所讨论的均是凸轮的顺序测量方法，有关凸轮的逆序测量(反求工程)方法，尚未见于文字。本文将对凸轮的逆序测量方法进行探讨。     

油煤浆的管道输送特性与管路设计原则

通过理论分析和管道实验，探讨了油煤浆在工业管道输送中的流变特性、流动状态和阻力特性，得出了油煤浆的物性参数、表观参数、管道阻力参数的测定值和计算公式，并在此基础上探讨了油煤浆管道输送的设计原则，为油煤浆管路的设计提供基础数据、计算方法和一般原则。     

小议变动成本法的合理性

企业对盈亏临界点的计算通常是以变动成本法为基础，但也有以制造成本法为计算基础的，对于这两种成本方法计算的几种盈亏临界点的情况，本文结合案例，通过比较分析认为：盈亏临界点的计算应当以变动成本法为基础更为合理。     

Synthesis of polymeric pour point depressants for Nada crude oil (Gujarat,India) and its impact on oil rheology

Five flow improvers have been synthesized to study rheological properties of Nada crude oil (Gujarat, India). Anhydride copolymers were prepared making use of the copolymerization of acrylates of different alkyls with maleic anhydride and the Poly (n-alkyl acrylates-co-N-hexadecylmaleimide) were prepared by the reaction of copolymer with hexadecylamine. The additives were purified and characterized by FTIR, GPC. The prepared polymeric additives shows dual function both as wax dispersants and flow improvers and all of them acts as good pour point depressants. Yield stress and the viscosity of the crude oil at different temperatures and concentrations of additives were evaluated by zero friction advanced rheometer AR-500 of TA instrument. Comparison of morphologies and structures of wax crystals or aggregates in waxy crude oils beneficiated with and without a PPD was also done by micro photographic studies which show the modification in wax crystal morphology due to additives.     

Effect of composition on gelation kinetics of unfilled and nanoapatite-filled poly(lactide-ethylene oxide-fumarate) hydrogels

Oscillatory shear rheometry at small strains was used to investigate the effects of composition (concentration of macromer, crosslinker, initiator/accelerator, and filler) on the gel point and ultimate storage modulus of poly(l-lactide-co-ethylene oxide-co-fumarate) (PLEOF) hydrogels. PLEOF in situ polymerizing hydrogels can be used as biodegradable scaffolds for cell encapsulation and tissue regeneration. The time evolution of the viscoelastic properties of the polymerizing mixture during the sol-gel transition was monitored using mechanical rheometry. According to the results, while the ultimate storage modulus linearly increased with the concentration of methylene bisacrylamide (BISAM) crosslinker, the values of the storage and loss moduli at the gel point were insensitive to the concentration of BISAM. Similar behavior was observed for PLEOF hydrogels reinforced with hydroxyapatite nanoparticles.     

基于可拓学模型的大批量定制实施方法分析

简要阐述了当前企业环境的特点，分析了大批量定制及其可拓学模型；然后，从可拓学中的可拓工程出发，以“系列化”、“变型结构设计”和“变型工艺设计”为例，说明了可拓学在实施大批量定制中的应用，为企业寻找新的、有效的大批量定制实施方法提供料新的思路和工具。     

“两步法”求取双目视觉传感器中摄象机位置关系

根据平行线“消隐点”理论，提出了用于双目视觉传感器自标定的“两步法”。该方法仅需４对消隐点象面坐标便可线性求解出旋转矩阵，再用２个空间点坐标便可线性求解出平移矢量。     

直流系统接地探测的微机集散监测系统的开发

文中介绍了根据低频信号变频探测原理和计算机控制技术研制开发的直流系统接地计算机集散监测系统。该系统的开发解决了我国电力系统中直流系统接地点探测长期不能自动监测的难题。