A complete VARMA modelling methodology based on scalar components

Abstract. This article proposes an extension to scalar component methodology for the identification and estimation of VARMA models. The complete methodology determines the exact positions of all free parameters in any VARMA model with a predetermined embedded scalar component structure. This leads to an exactly identified system of equations that is estimated using full information maximum likelihood.     

Characterization of supported Pd-Pt catalysts by chemical probes

The temperature programmed (palladium) hydride decomposition appeared very effective method for diagnosing the extent of alloying in Pd-Pt/SiO₂ catalysts. Introduction of Pt to Pd catalysts moves the TPHD peak gradually towards lower temperatures and the shift in hydride decomposition peak is accompanied by a decrease in the amount of released hydrogen. The catalysts prepared the direct redox method showed much better alloy homogeneity than the samples prepared by coimpregnation. The results of probing with other techniques, i.e. catalytic probing with hydrodechlorination of CCl₂F₂ and XRD, were in line with TPHD data. The catalytic probing showed the presence of synergistic effect, a clear indication of Pd-Pt mixing. XRD data of post-reaction samples showed carbon incorporation into Pd-rich phase, whereas separate Pt-rich phase did not experience any bulk carbiding.     

基于LabWindows/CVI的多线程测控软件设计技术

多线程技术是W in32操作系统的一项重要软件技术。CVI 6.0及其以后版本提供了线程池和异步定时器两种多线程运行机制,为测控软件的设计开发带来了一次技术飞跃。文中结合测控软件设计实例,详细介绍了在CVI平台下多线程编程技术的应用方法。     

New multiresolution modeling techniques in CAD

To apply wavelet transformation to CAD surface model composed of multiple surface patches, an algorithm called wavelet signal separation to preserve geometric constraints during wavelet transformation is proposed. The algorithm divides the B-spline control points into those associated and those unassociated with the geometric constraints. Through preserving the signal information associated with the constraint control points, the geometric constraints can be automatically preserved after wavelet transformation. This paper also briefly investigates two types of the detail feature propagation technique in wavelet-based multiresolution CAD system. One is detail feature motion. The other is detail feature repetition. Finally, a comprehensive example is presented to illustrate the effects of the combination of those techniques.     

2RE69/Zr702双金属管氨汽提塔关键部件的设计与制造

介绍了2RE69／Zr702双金属管的特殊结构、优良耐蚀性能，与管板的连接接头型式及焊接工艺、管头及液体分布器加工、装配和试验。     

基于HMS87C1408B的籽棉、菜籽和粮食水分综合测试仪

介绍了使用HMS87C1408B作为主控芯片的籽棉、菜籽和粮食水分综合测试仪的实现方法,重点说明了阻抗变换、软件驱动LCD和语音播报技术的实施.     

吸水膨胀型膨润土/交联聚丙烯酰胺颗粒堵剂

使丙烯酰胺、少量N，N-亚甲基双丙烯酰胺在钙膨润土存在下进行水溶液引发接枝共聚合，聚合产物经造粒、粉碎、筛分，得到粒径0．5～1．0mm的颗粒堵剂。根据颗粒堵剂吸水量大小确定丙烯酰胺与膨润土最佳质量比为7：1，引发剂最佳用量为500g／t，交联剂最佳用量为300g／t，吸水量与这3个参数之间的关系曲线都经过最大值，颗粒堵剂在去离子水中的吸水量为560～650mL/g。该堵剂已大规模生产，在胜利、中原油田许多采油厂已用于调剖、堵水和调驱施工，在青海、江苏、大港、冀东等油田也已开始使用。在胜利东辛采油厂的一个井组，连续3个月在3口井注入该堵剂共27t，使井口压力上升3MPa，产油量大幅度增加。表l参l。     

聚合物凝胶用Cr3+交联剂检测方法探讨

胜利油田交联聚合物驱、封堵大孔道中使用Cr3+交联的HPAM凝胶。探讨了Cr3+交联剂的检测方法。将4种商品HPAM和6种商品Cr3+交联剂在矿化度5727mg/L、钙镁含量108mg/L的胜利盐水中配制成24个HPAM/Cr3+成胶溶液,根据70℃下反应72h后在70℃测定的凝胶相对强度(要求在代码C以上),确定使用分子量1.11×107、水解度28.8%的一种HPAM,配液浓度为1300mg/L。推荐采用在70℃、振荡频率f=0.422s-1测定的复数粘度η 和储能模量G′表示凝胶的强度,给出了HPAM浓度不同、各Cr3+交联剂浓度为最低需要量的6种凝胶的η 和G′值;推荐取G′值达到0.1Pa的时间为成胶时间,由上述6种体系的G′ t曲线求出成胶时间在98～300min范围。提出其他应测定的性能包括:成胶溶液抗剪切性,凝胶热稳定性(抗热老化性),凝胶抗温性,凝胶抗盐性及岩心堵水率,对测定方法作了详略不等的讨论。特别指出,用于热老化实验的成胶溶液必须彻底除氧,否则粘时曲线的变化将无规律(给出了实例)。图7表7参3。     

Computations of Explosive Boiling in Microgravity

Dynamics of the explosive growth of a vapor bubble in microgravity is investigated by direct numerical simulation. A front tracking/finite difference technique is used to solve for the velocity and the temperature field in both phases and to account for inertia, viscosity, and surface deformation. The method is validated by comparison of the numerical results with the available analytical formulations such as the evaporation of a one-dimensional liquid/vapor interface, frequency of oscillations of capillary waves, and other numerical results. Evolution of a three-dimensional vapor nucleus during explosive boiling is followed and a fine scale structure similar to experimental results is observed. Two-dimensional simulations yield a similar qualitative instability growth.