The spiral model of collaborative knowledge improvement: an exploratory study of a networked collaborative classroom

International Journal of Computer-Supported Collaborative Learning - While there are many studies on students’ collaborative learning at the small group level, pedagogies and strategies for...     

Fabrication of micro pin fins on inclined V-shaped microchannel walls via laser micromilling

A laser-micromilling process was developed for fabricating micro pin fins on inclined V-shaped microchannel walls for enhanced microchannel heat sinks. A pulsed nanosecond fiber laser was utilized. The feasibility and mechanism of the formation of micro pin fins on inclined microchannel walls were investigated for a wide range of processing parameters. The effects of the laser output power, scanning speed, and line spacing on the surface morphologies and geometric sizes of the micro-pin fins were comprehensively examined, together with the material removal mechanisms. Micro pin fins with acute cone tips were readily formed on the V-shaped microchannel walls via the piling of recast layers and the downflow of re-solidified materials in the laser-ablation process. The pin-fin height exhibited an increasing trend when the scanning speed increased from 100 mm/s to 300 mm/s, and it decreased continuously when the line spacing increased from 5 μm to 20 μm. The optimal processing parameters for preparing micro pin fins on V-shaped microchannels were found to be a laser output power of 21 W, scanning speed of 100–300 mm/s, and line spacing of 2–5 μm. Moreover, the V-shaped microchannels with micro pin fins induced a 7%–538% boiling heat-transfer enhancement over their counterpart without micro pin fins.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-021-00382-x     

SS-DEWMA图多目标优化及在输出传感器故障检测中的应用

针对平方和双指数加权移动平均(SS-DEWMA)图难以选取合适参数同时满足数据监控的多个指标最优的问题,提出一种SS-DEWMA图的多目标优化(MO-SS-DEWMA图)数据监控方法,并将该方法用于非线性系统传感器的故障检测.首先,采用复合嵌入式均方根容积卡尔曼滤波器(CESCKF)对系统状态进行估计,并产生残差;其次...     

Experimental Investigation of White Layer Thickness on EDM Processed Silicon Steel Using ANFIS Approach

Since the white layer thickness influences the surface quality of the machined specimens using electrical discharge machining process, the prediction of su     

利用中国红花岗石边角料生产无机人造石

本文对利用红色花岗石边角料为骨料,以无机胶凝材料作为胶结料,并配以红色无机颜料及其他外加剂,生产红色人造石进行了研究。结果显示,制品养护至28d时的抗压强度为92.8 MPa,抗折强度为11.9 MPa,吸水率为3.46%,光泽度为63.8光泽单位,其性能超过国家建材行业标准《建筑装饰用水磨石——水泥人造石》(JC/T507—2012)的指标。放射性属于国家标准的A类装饰装修材料,产销和使用范围不受限制。     

激光烧蚀法制备准一维纳米材料

介绍了当前激光烧蚀法制备纳米丝、纳米管和纳米电缆的研究现状,讨论了准一维纳米材料激光烧蚀法制备的系统设备和制备条件,分析了激光烧蚀法制备准一维纳米材料的特点和发展趋势.认为准一维纳米材料是气相粒子在高温催化剂作用下生成的.激光烧蚀法具有洁净、可控性强及适应面广的特点.     

优选黏土稳定剂的室内实验研究

选取大庆油田某A组储层的天然岩心,气测渗透率分别为0.274μm2、0.442μm2和0.766μm2,针对中低渗透储层黏土含量较高的实际情况,为优选适用于该储层注水开发的黏土稳定剂,进行了液体(聚季铵盐黏土稳定剂DNT-014)、固体(QY-138)和复配盐黏稳剂(A储层强水敏型配伍液)3种黏土稳定剂的膨胀率测定实验、岩心伤害率实验和对比驱替实验。结果表明:A组储层3种不同渗透率的天然岩心,分别加入液体、固体和复配盐3种黏稳剂后,其膨胀率在1.13%～1.22%,但只有液体黏稳剂DNT-014的加入,3种岩心均不产生颗粒。黏稳剂DNT-014和QY-138的加入,对岩心渗透率伤害较小,最高伤害率分别为13.4%和19.17%;加入复配盐黏稳剂后,对岩心渗透率伤害最大,最高伤害率达32.48%。DNT-014的加入,对储层黏土矿物的膨胀和运移起到防控作用,与储层配伍性最好,对渗透率伤害最小,且达到一定注入倍数后,伤害率不再增长。针对A组储层,注水开发中应优选液体黏稳剂DNT-014。     

超声波处理对鲢鱼鱼肉蛋白性质的影响

研究了超声功率和超声处理时间对鲢鱼肉蛋白性质的影响。结果表明,160 W~320 W超声作用15 min,鱼肉蛋白的溶解度、乳化性及乳化稳定性、起泡性及气泡稳定性随超声功率的提高均呈现先增大后减小的趋势,溶解度、乳化性及乳化稳定性在240 W超声作用时最高;起泡性及气泡稳定性在超声功率160 W时最高。160 W超声作用5 min~25 min,鱼肉蛋白的溶解度、乳化性及乳化稳定性、起泡性及气泡稳定性随超声作用时间的延长均先增大后减小。其中,溶解度、乳化性、起泡性及气泡稳定性在超声作用10 min时最高;乳化稳定性在超声作用15 min时最高。由此说明,超声波处理会导致鱼肉蛋白性质改变,且与超声作用功率和时间有一定的相关性。