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81.
疏水缔合型聚丙烯酰胺的合成与性能评价 总被引:1,自引:0,他引:1
为了提高高相对分子质量的聚丙烯酰胺的抗温抗盐性能,利用自制的两亲表面活性单体与丙烯酰胺共聚合成了疏水缔合型聚丙烯酰胺并进行室内评价。结果表明,在高温、高盐、高钙条件下,合成的疏水缔合型聚丙烯酰胺具有良好的增粘性和较强的热稳定性;克服了疏水缔合型聚合物在盐水中溶解性差的问题,可用各种矿化度的盐水和油田产出污水配制;具有良好的无机盐增粘性能和抗温性能。 相似文献
82.
测试了氧化锌颗粒膜电阻响应-恢复特性,讨论了颗粒形态,加热电压、环境气氛、气氛浓度和注入方式等因素对电阻响应-恢复特性的影响。结果表明,随着加热电压的升高,电阻响应-恢复的速度和程度明显加大;断续注入时颗粒膜电阻值的响应随着浓度的增加逐步减弱. 相似文献
83.
In the present work, the ohmic resistance of an integrated planar-SOFC (IP-SOFC) has been evaluated by developing a model
whose equations have been solved numerically through an FEM method. The model allows to estimate the distribution of voltage
and current density in the cell. A comparison between simulated and experimental data of area specific resistance is reported,
which shows satisfactory agreement. The mathematical model has also been used to carry out some parametric studies for optimisation
purposes. Indeed, a reduction in cell pitch length and an increase in electrode thickness are predicted to lead to a reduction
in ohmic losses in IP-SOFCs. 相似文献
84.
Graft copolymers of sodium alginate (NaAlg) with N‐vinyl‐2‐pyrrolidone were prepared using azobisisobutyronitrile as initiator. The graft copolymers (NaAlg‐g‐PVP) were characterized with Fourier transform infrared spectroscopy, elemental analysis, and differential scanning calorimetry. Polymeric hydrogel beads of NaAlg and NaAlg‐g‐PVP were prepared by crosslinking method using glutaraldehyde (GA) as a crosslinker in the hydrochloric acid catalyst (HCl) and these beads were used to deliver anti‐inflammatory drug, indomethacin (IM). Chemical stability of the IM after encapsulation into beads was confirmed by FTIR. Preparation conditions of the NaAlg‐g‐PVP beads were optimized by considering the percentage entrapment efficiency, particle size, swelling capacity and their release data. In vitro release studies were performed in simulated gastric fluid (pH 1.2) for the initial 2 h, followed by simulated intestinal fluid (pH 7.4) for 4 h. Effects of GA concentration, exposure time to GA, drug/polymer (d/p) ratio, and concentration of HCl on the release of IM were discussed. It was observed that IM release from the beads decreased with increasing GA concentration and exposure time. IM release also decreases with increasing d/p ratio and HCl concentration. The highest IM release was obtained to be 77% for beads crosslinked with 0.027M GA. Swelling experiments were also performed to compute molecular mass between crosslinks of the beads. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
85.
We have calculated thermal conductivity of alumina nanofluids (with water and ethylene glycol as base fluids) using temperature
as well as concentration-dependent viscosity, η. The temperature profile of η is obtained using Gaussian fit to the available experimental data. In the model, the interfacial resistance effects are incorporated
through a phenomenological parameter α. The micro-convection of the alumina nanoparticle (diameter less than 100 nm) is included through Reynolds and Prandtl numbers.
The model is further improved by explicitly incorporating the thermal conductivity of the nanolayer surrounding the nanoparticles.
Using this improved model, thermal conductivity of copper nanofluid is calculated. These calculations capture the particle
concentration-dependent thermal conductivity and predict the dependence of the thermal conductivity on the size of the nanoparticle.
These studies are significant to understand the underlying processes of heat transport in nanofluids and are crucial to design
superior coolants of next generation. 相似文献
86.
87.
对T形线路的故障测距,现有方法都是先判断故障支路,再将3端线路等效成2端线路进行测距。但在 T节点附近短路,尤其是经高阻短路时,现有的测距方法由于无法正确判别故障支路而存在一定范围的测距死区。针对上述缺陷,分别假设故障发生在某一支路,由假定正常的2段支路端的电压、电流推算求得 T节点电压和注入假定故障支路的电流,从而分别求得3个故障距离。经证明,求得的3个故障距离有且仅有1个在0和对应支路总长度之间,该距离就是真实的故障距离,故障发生在对应支路上。该方法无需事先判别故障支路即可测距,在 T节点附近经高阻故障时无测距死区。其测距精度理论上不受过渡电阻和故障类型影响,无需故障前数据,且对滤波无高要求。EMTP仿真结果表明该方法正确、有效,测距精度高。 相似文献
88.
Blanchard Kimberly A.; Morgenstern Jon; Morgan Thomas J.; Lobouvie Erich W.; Bux Donald A. 《Canadian Metallurgical Quarterly》2003,17(4):328
Negative consequences are an important component of the substance use change process, yet no standardized measure exists to assess consequences of use. This study evaluated the psychometric properties of the Inventory of Drug Use Consequences, a self-report measure assessing drinking and drug use consequences. Participants (N=252) were assessed at entry into outpatient substance abuse treatment. Items loaded strongly on 1 factor, and internal consistency of the total scale was high. Fifteen items with the highest correlations with the total scale were chosen to represent the construct. The shortened measure exhibited good internal consistency, convergent and discriminant validity, and detected change over time and may be the measure of substance use consequences that is lacking in the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
In this paper an extension of the method of the Fourier series expansion to the fire analysis of composite beams is presented. In particular the extension concerns the introduction of the temperature dependent interaction of all the components: steel beams, concrete slab and steel connectors. These last are considered of finite stiffness, and a proper account is given to the combined effect of thermal degradation of the properties, and stress amplification caused by the differential thermal expansion across the interface.The proposed method compares very well with some experimental fire tests of simply supported and framed composite beams. Due to its relative simplicity and speed, it can be used for design purposes in evaluating the critical temperature in terms of critical deflection. Finally we recall that the method is capable of dealing with every type of fastening distribution, such as discontinuous or variable length. 相似文献
90.
对铸造高性能合金Lewmet55进行了化学成分设计,确定了该合金中镍、铬、钼、铜和硅的含量。采用金相显微镜和X射线衍射相结合的方法,分析了该合金的显微组织,并采用多种腐蚀试验方法研究其耐腐蚀行为。着重研究了不同热处理制度对铸造高性能合金的均匀腐蚀、晶问腐蚀、点蚀和电化学腐蚀性能的影响。试验结果表明,Lewment55合金经1250℃×1.5h水冷固溶处理后,在高温浓硫酸介质中具有良好的耐蚀性,以及较好的抗晶间腐蚀、点蚀和电化学腐蚀性能。 相似文献