High-Tg porous polyimide films with low dielectric constant derived from spiro-(adamantane-2,9′(2′,7′-diamino)-fluorene)

Porous polyimide (PI) films with low dielectric constants and excellent thermal properties have been a pressing demand for the next generation of high-performance, miniature, and ultrathin microelectronic devices. A series of novel porous PI films containing fluorenyl-adamantane groups were prepared successfully via thermolysis of poly(ethylene glycol) (PEG) added in the PI matrix. The cross-sectional morphologies of porous PI films showed closed pores with diameters ranging from 135 to 158 nm, which were uniform and regular in shape without interconnectivity. These porous PI films exhibited excellent thermal properties with a glass-transition temperature at 376 °C whereas the 5% weight loss temperature in air excess of 405 °C due to enhanced rigidity afforded by fluorenyl-adamantane groups. Accompanied by thermolysis content of PEG increasing from 0 to 20 wt %, the density of porous PI films decreased, and the corresponding porosity grew significantly from 0 to 11.48%. Depending on porosity, the dielectric constant and dielectric loss of porous PI films significantly declined from 2.89 to 2.37 and from 0.050 to 0.021, respectively. These excellent properties benefit the as-prepared porous PI films for application as interlayer dielectrics, integrated circuit chips, or multichip modules in microelectronic fields. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47313.     

Small‐Sized High‐Power PIN Diode Switch with Defected Ground Structure for Wireless Broadband Internet

This letter presents a small‐sized, high‐power single‐pole double‐throw (SPDT) switch with defected ground structure (DGS) for wireless broadband Internet application. To reduce the circuit size by using a slow‐wave characteristic, the DGS is used for the quarter‐wave (°/4) transmission line of the switch. To secure a high degree of isolation, the switch with DGS is composed of shunt‐connected PIN diodes. It shows an insertion loss of 0.8 dB, an isolation of 50 dB or more, and power capability of at least 50 W at 2.3 GHz. The switch shows very similar performance to the conventional shunt‐type switch, but the circuit size is reduced by about 50% simply with the use of DGS patterns.     

Study on Hydrocracking of VGO Derived from Kazakhstan-Russian Mixed Crude

1 Introduction With the successful completion of the construction of the China-Kazakhstan oil pipeline the refinery at Dushanzi Pet- rochemical Company will process the Kazakhstan-Russian mixed crude at full steam starting 2007. The high sulfur, nitro- gen and heavy metals contents in the Kazakhstan-Russian mixed crude would have a serious impact on the secondary processing units of the Dushanzi refinery, in particular on the distillate hydrocracking unit, which mainly operates on vacuum g…     

声波测井换能器激发响应实验研究

声波测井换能器的激发响应由换能器振动时所表现出来的动态阻抗和激发电路参数决定。而换能器的动态（阻抗）参数随压电晶体及其装配方式（力学边界条件）改变。为了测量换能器动态参数的影响，采用声波测井仪器常用的压电晶体和升压变压器，通过改变激发脉冲宽度和直流电压进行了实验，结果发现：在换能器两端的瞬态响应中，一共有三个二阶网络响应，分别对应于不同的频率。最低的一个影响声波测井波形的基线、与换能器主频接近的一个决定激发效率以及电路与压电晶体之间的匹配关系，是激发电路设计中比较关键的，其参数可以通过导纳圆测量仪器得到。     

岩石圈深部温度压力条件下褐煤与水的热模拟研究

在压力高达1—3GPa、温度为400—700℃的条件下，在密闭体系中进行了褐煤加水的模拟实验。分析了实验产物中液态烃的变化规律，并讨论了压力、温度及恒温时间对有机质演化的影响。实验结果表明，热模拟液态产物氯仿沥青“A”的有机碳含量为0．91％-2．55％，2GPa条件下其高峰值后移至700℃，说明高压抑制了液态烃的生成，同时压力升高有利于有机质降解产物的环化、聚合和芳构化。在400—600℃条件下，温度升高或恒温时间增长，OEP和Pr／Ph值均减小；而在700℃的恒温条件下，压力增高，OEP和Pr／Ph值均增大。说明有机质的成熟度与温度和加热时间成正相关，而压力增加抑制了有机质的成熟演化。在高压条件下，芳烃演化的主要趋势是甲基化作用，压力升高有利于甲基化反应和甲基重排。     

灰色预测模型在油气操作成本预测中的应用

油气操作成本是油气田生产消耗的主要项目，为了有效地控制油气操作成本，必须制定准确的油气操作成本计划。而油气操作成本在我国是最近几年才提出来的，数据项比较少，给油气操作成本预测带来一定的难度。为此，文章根据灰色预测的基本原理，采用灰色系统理论进行油气操作成本预测，就可以弥补对预测所需的数据少，而且也无须剔除不可比因素，只要所建模型能满足精度要求，预测结果就可以信赖。     

基于FPGA技术的可重构软测量系统

介绍了一种基于FPGA（Field Programmable Gates Array）技术的可重构的软测量系统。该系统由一个单片机控制着一片FPGA芯片，芯片上配置的软测量模型在一个BP人工神经网络模型及其训练模型之间切换（即重构）。该系统在实际中有广泛的用途，如测量工业生产中的过程变量、生物体内部状态、海洋探测、空间设备等。     

新会计准则对会计准则质量的影响

年初,国家财政部发布了新的会计准则,这是中国会计准则建设史上的重大事件。新会计准则体现出会计准则质量的几个重要标准,提高了中国会计准则的质量。同时,分析新会计准则质量方面仍存在的一些不足。     

循环流化床固-固换热系统传热规律

在自制的循环流化床固-固换热设备中,以催化裂化平衡催化剂[平均粒径60μm,堆密度980 kg/m3,比热1.01 kJ/(kg.K),临界流化速度0.002 1 m/s]为原料,对系统的循环特性及传热规律进行了研究,考察了床层密度、提升风量、床层温度、催化剂粒径等因素对传热的影响。结果表明,随着提升风量增加,表观气速增大,床层密度下降,传热系数下降;提高床层温度,减小催化剂的粒径,传热系数增加。     

应用API 581对输气站场进行定量风险评价

目前专门针对输气站场的风险评价方法还不多，现有的手段也只是根据国家法律法规得出定性的评价结果，然后按照评价结果对照得出整改方案。为此，对输气站场的定量风险评价工作提出了一套新方法，得到了定量的和更加客观的风险排序，为管道站场的完整性管理工作提供了有力的支持；并以陕京输气管道榆林压气站为例，应用美国石油学会标准API 581（基于风险检测的基本源文件）对站内设施进行了风险评价，计算了站内设备和管线的失效后果、失效概率，得到了定量风险值，进而分析了风险值产生差异的原因。最后，针对我国输气管道风险评估工作提出了看法和建议。