One-step purification of ethylene from acetylene and carbon dioxide by ultramicroporous carbons

The one-step adsorptive separation of high-purity ethylene (C₂H₄) from a ternary gas mixture (C₂H₂/C₂H₄/CO₂) is challenging and has not been reported on porous carbons. Herein, we report camphor seeds husk-derived ultramicroporous carbons (CSHs) show high affinities toward acetylene (C₂H₂) and carbon dioxide (CO₂) over C₂H₄. The optimized CSH-2-700 with high heteroatom contents and centered pore size distributions shows high C₂H₂ adsorption capacity (2.24 mmol g⁻¹) and record ideal adsorbed solution theory (IAST) C₂H₂/C₂H₄ selectivity (10.2) among one-step C₂H₄ purification adsorbents. Meanwhile, CSH carbons are the only carbon adsorbents that preferentially adsorb CO₂ over C₂H₄, with a CO₂/C₂H₄ selectivity of 1.9 under ambient conditions. Furthermore, dynamic breakthrough experiments verified its feasibility for one-step C₂H₄ purification from a three-component C₂H₂/C₂H₄/CO₂ gas-mixture.     

阳离子淀粉接枝窄相对分子质量阴离子聚丙烯酰胺制备干增强剂

用阳离子淀粉接枝窄相对分子质量阴离子聚丙烯酰胺制备干增强剂。通过探索性实验,所合成出来的产品具有用量少,增强效果好等特点。     

竖直矩形窄通道内水流动沸腾换热特性的研究

建立单面加热垂直矩形窄通道流动沸腾换热试验装置,针对截面250mm×3.5mm的窄缝通道,对水流动沸腾换热特性进行试验研究。通过试验分析可知:(1)随着干度的增加,局部换热系数先增加后减小,有一个最大值,此时处于饱和核沸腾区域,其蒸汽干度也接近于0,同时也接近于沸腾起始点。相应地流体从单相流-泡状-块状流-搅拌-环状流转变。(2)在流动沸腾换热中,热流密度对核态沸腾换热有明显影响,而对流动沸腾液膜蒸发的影响甚小,所以可以认为由热流密度的变化而引起的换热变化,主要表现在核态沸腾。(3)入口温度的变化对单相流动的换热系数有影响,而沸腾换热系数与流型及汽泡的产生及扰动有极大关系,入口温度对流动沸腾局部换热系数基本没有影响。     

基于FPGA平台的窄脉冲大电流LED频闪光源设计

针对高频信号的特点,利用FPGA,设计了一种窄脉宽、大电流的LED频闪光源。通过FPGA平台上的编程控制,实现了满足频闪光源控制时序要求的窄脉宽信号。最后,将窄脉宽信号进行电流放大,获得脉宽为ns级,电流最大可达30A的LED驱动脉冲信号。     

近期长江荆江河道演变特点

从长系列资料看,上游来水量无趋势性增大或减少,来沙量自20世纪90年代以来明显减少.入洞庭湖三口分流分沙呈减少趋势,尤其以藕池口衰减最为突出. 1998年大水造床作用明显,上荆江滩槽皆冲,以冲滩为主;下荆江表现为冲槽淤滩,总体呈淤积状态.还对重点河弯,如沙市、石首河段,自1998年大水以来的最新演变情况作了详细分析,主要特点表现为沙洲移动、主流线摆动,顶冲点普遍下移,崩岸时有发生.     

Research on droplet transfer in oscillating arc narrow gap GMA welding

In this paper, the droplet transfer in oscillating arc narrow gap gas metal arc （ GMA ） welding was studied. According to the experimental results, the oscillating arc has effect on the droplet transfer mode. The droplet transfer frequency in narrow gap groove is higher than that in bead-on-plate welding. Because of the change of arc location in narrow gap groove, the droplet transfer in oscillating arc narrow gap changes regularly. The droplet transfer frequency near groove sidewall is higher than that at the middle of narrow gap groove.     

浅谈我国钢制压力容器焊接新技术

针对我国钢制压力容器相对薄弱的焊接领域,如厚壁压力容器、承装腐蚀介质的压力容器和不锈钢复合板压力容器,介绍了我国钢制压力容器的焊接新技术,包括窄间隙多丝埋弧焊、激光-电弧复合热源、带极电渣堆焊、药芯焊丝CO2气保护焊、脉冲TIG焊;分析了焊接新技术在压力容器焊接中的应用,并对未来发展进行展望。     

特厚煤层分层综放开采区段小煤柱留设尺寸研究

砚北煤矿5煤为特厚煤层,煤层具有强冲击地压倾向性,为防治工作面两巷掘进时冲击地压现象发生,采用理论计算、数值模拟和现场观测的方法,研究分析工作面、区段护巷小煤柱内应力变化以及采场超前支承压力影响范围。以区段小煤柱变形破坏理论为依据,通过数值模拟分析了4种不同宽度煤柱的塑性区变化范围,最终得出适合砚北矿条件的合理区段煤柱宽度。     

井底恒压式与微流量式控压钻井系统控制机理差异分析

随着我国能源需求的不断增加,大量深层和复杂油气藏需要进行开采,伴随而来的各种钻井复杂问题也越来越多,其中钻井安全密度窗口窄的问题就是最为突出的问题之一。控压钻井技术目前是解决该问题最有效的办法。控压钻井技术按照其控制原理又可分为井底恒压式控压系统与微流量控压钻井系统。通过对这2种控压钻井方式的基本工艺流程及装备进行分析,比较2种控压钻井系统区别,为进一步推广控压钻井技术提供建议。     

Kinetics of emitted mass—A study with three dry powder inhaler devices

The purpose of this study was to understand the kinetics of emptying of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180 L min⁻¹) from three dry powder inhaler devices, Rotahaler^® (RH), Monodose Inhaler^® (MI) and Handihaler^® (HH). Aerosol concentration vs. time profiles, determined through real-time laser diffraction particle sizing, demonstrated that the majority of the powder from RH was emitted within one second while a more prolonged aerosolisation was observed from MI and HH. Peak aerosol concentrations were achieved more rapidly from RH compared to MI for both SS and LH300. Calculated cumulative emitted mass (CCEM) vs. time profiles were obtained from the aerosol concentration vs. time profiles and the emitted mass and the rate of CCEM (k_CCEM), estimated from a modelling approach, increased with increasing air flow rates. The k_CCEMvs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k_CCEM was highest from RH and lowest from MI. Differences in k_CCEM between the devices were related to capsule aperture size while the differences between the materials were due to the powder bed structure. This approach provided an understanding of the rate at which powder mass emptied from dry powder inhaler devices and was proposed to be a powerful development tool for the future powder inhalers.