Synthesis of SBA 15 graphene oxide composite membrane using phenol–formaldehyde resin pore modifier for CO2 separation

Present study highlights the development of carbon-loaded SBA 15 membrane on clay-alumina tubular support and its performance on the CO₂ separation efficiencies from different mixture gases. To modify the large pores of SBA 15 by graphitic carbon, low molecular weight phenol–formaldehyde (PF) resin was incorporated into the mesoporous channel followed by calcination under inert atmosphere. The modified ordered pore structure of the membrane has been characterized by low-angle XRD, TEM, and pore size distribution analysis. The chemical state of the deposited carbon phase into the SBA 15 pores was analyzed by X-ray photoelectron and Raman spectroscopy. Carbon having graphitic nature mainly in graphene oxide has been deposited into the mesopore of SBA 15 resulting decrease in pore size from 8.9 to 1.0 nm. Finally, the developed SBA 15 carbon membranes were characterized by CO₂ permeation and separation selectivity of CO₂/CH₄, CO₂/CO. Highest CO₂/CH₄ separation factor was achieved as 16.9 with CO₂ permeance 13.6 × 10^–8 mol/m²/s/Pa at 200 kPa feed pressure by the 20% resin with 2 times coated membrane. In flue gas analysis, highest CO₂/CO separation factor of 32.8 was achieved. This study offers an observation on CO₂ separation from simulated BF gas for the first time and the results show the potential of the developed SBA 15/C composite membranes in commercial application.     

Periodic autoregressive conditional duration

We propose an autoregressive conditional duration (ACD) model with periodic time-varying parameters and multiplicative error form. We name this model periodic autoregressive conditional duration (PACD). First, we study the stability properties and the moment structures of it. Second, we estimate the model parameters, using (profile and two-stage) Gamma quasi-maximum likelihood estimates (QMLEs), the asymptotic properties of which are examined under general regularity conditions. Our estimation method encompasses the exponential QMLE, as a particular case. The proposed methodology is illustrated with simulated data and two empirical applications on forecasting Bitcoin trading volume and realized volatility. We found that the PACD produces better in-sample and out-of-sample forecasts than the standard ACD.     

稳定平台中通用陀螺数据采集处理系统

为提高稳定平台的性能,针对平台中各种类型陀螺高速度、高精度、宽动态范围的设计指标要求,研制了一种通用数据采集处理系统。在详细分析动力调谐、光纤和微机械陀螺典型型号性能参数指标的基础上,提出了系统的设计指标要求,选择8通道24位∑-？高精度模数转换器ADS1278和32位数字信号处理器TMS320F2812,设计实现系统的硬件电路,编写了相关的软件程序,并进行了实验验证。实验表明：系统的转台测试数据与陀螺出厂标定的性能参数之间,测量误差小于1%,完全满足稳定平台中陀螺的应用要求。     

高架桥梁应变检测分析仪的研制

为了精确测量高架桥梁的应变量,用一种以新型金属应变片作为敏感元件,用Cygnal F020单片机作为智能测控部件,研制出桥梁应变检测分析仪.该仪器小型轻便,操作界面友好,检测精确可达0.01.既可单机使用,本机显示和打印测量结果;又可通过USB接口与笔记本电脑(PC机)配合使用,显示、打印和分析测量结果.     

基于Simplorer的无刷直流电动机系统设计与仿真

针对无刷直流电动机的控制系统,设计了以TMS320F2812 DSP为核心的数字控制器,采用速度环和电流环双闭环的控制策略,给出了系统设计框图和部分外围电路硬件设计图;介绍了基于Simplorer的无刷直流电动机系统建模仿真的实现过程,仿真结果表明：系统具有良好的动静态性能,所提出控制策略实现简单且具有实用价值。     

Q-I-Q-T工艺对60Si2CrVA钢断裂韧性的影响

研究60Si2CrVA弹簧钢经淬火-等温-淬火-回火(Q-I-Q-T)热处理后复相组织含量与断裂韧性间的关系。结果表明,在实验的等温温度范围内,随着等温温度的升高,残余奥氏体和贝氏体含量逐渐增大,60Si2CrVA钢强度降低,断裂韧性逐渐增加,在300℃等温时,断裂韧性达到最大值66.37 MPa.m1/2。稳定的残留奥氏体与过渡形态贝氏体量增加是提高断裂韧性的主要原因。     

Q235焊缝表面镍基合金熔覆层在NaCl溶液中的腐蚀行为

目的 采用激光、等离子熔覆技术在低碳钢焊缝表面制备镍基耐腐蚀涂层,提高钢管焊缝表面的耐蚀性能。方法 通过浸泡腐蚀、动电位极化法、交流阻抗法,研究不同试样在质量分数为3.5%的NaCl溶液中的腐蚀行为。利用OM、SEM、EDS和XPS分析腐蚀试样表面、截面的微观组织和腐蚀产物成分。结果 采用激光、等离子熔覆技术均可制得成形良好、表面光滑、无宏观裂纹的涂层,且表现出良好的抗点蚀能力;等离子熔覆层晶粒相较于激光熔覆层晶粒更均匀、细小,析出的碳化物(Cr₂₃C₆、Cr₇C₃)、硼化物(CrB)等硬质点提高了涂层的硬度,对于抗蚀性有着积极的作用。试样的耐蚀性排序为等离子熔覆层>激光熔覆层>基体。浸泡失重腐蚀实验表明,基体、激光熔覆层、等离子熔覆层的腐蚀速率分别为0.182 9、0.125 6、0.102 7 g/(m²·h)。从极化曲线看出,激光熔覆层(-0.503 4 V)、等离子熔覆层(-0.546 6 V)的自腐蚀电位相较于基体(-0.858 4 V)发生了正移。基体、...     

低渗透储层分类标准及其综合评价——以敖包塔-葡萄花油田FⅡ油层组为例

敖包塔-葡萄花油田钻遇扶杨油层FⅡ油层组有效孔隙度主要分布在10%~15%之间,平均为12.6%;空气渗透率一般分布在0.1~10×10-3μm2之间,属低孔、特低渗透性储层。通过对选用7项宏观参数与7项微观参数确定储层综合评价参数并建立分类标准,确定出每个评价参数的分级标准,将敖包塔-葡萄花油田FⅡ油层组的储层分为四类,其中Ⅰ类最好,为低渗透储层;Ⅱ类次之,为特低渗透储层;Ⅲ类再次之,为超低渗透储层;Ⅳ类储层最差,为极差储层。依据专家经验及大量反复实验的结果上确定了权重系数,预测了FⅡ油层组的储层有利区带,结果表明敖包塔-葡萄花油田FⅡ油层组以Ⅰ类储层和Ⅱ类储层区为主,其中最有利储层区(Ⅰ类储层区)主要呈条带状分布于研究区北部的葡332~葡54~葡115-51、葡31、葡462、敖10等井区。     

全氟己酮和细水雾抑制三元锂离子电池火灾有效性研究

锂离子电池热失控是造成电动汽车火灾事故的首要因素。文章概述了车用锂离子电池热失控火灾危险性及抑制方法,并开展了全氟己酮、细水雾对车用三元锂离子电池热失控火灾的灭火试验。结果表明,三元锂离子电池热失控时表面最高温度超过500℃,表面最大升温速率达到18.93℃/s;全氟己酮灭火剂和细水雾均能有效扑灭电池初期明火,但在灭火后数分钟内电池发生复燃。两种灭火剂均能有效降低电池表面最高温度和最大升温速率。