Determination of Trace Amounts of Gold in Soil Sample Using Plastic Foam Enrichment-ICP-MS Method

The aim of this study is to determine the trace amount of gold in soil sample using plastic foam enrichment-ICP-MS method.The national standard reference materials including GAu-2,GAu-10,GAu-11 and GAu-13 were used for parallel determination by ICPMS.The results showed that the method performed well in detection limit,precision and accuracy,indicating that the plastic foam enrichment-ICP-MS method could be used to determine the trace amounts of gold in soil sample.

Numerical Predictions of the Effective Thermal Conductivity of the Rigid Polyurethane Foam

A reconstruction method is proposed for the polyurethane foam and then a complete numerical method is developed to predict the effective thermal conductivity of the polyurethane foam. The finite volume method is applied to solve the 2D heterogeneous pure conduction. The lattice Boltzmann method is adopted to solve the 1D homogenous radiative transfer equation rather than Rosseland approximation equation. The lattice Boltzmann method is then adopted to solve 1D homogeneous conduction-radiation energy transport equation considering the combined effect of conduction and radiation. To validate the accuracy of the present method, the hot disk method is adopted to measure the effective thermal conductivity of the polyurethane foams at different temperature. The numerical results agree well with the experimental data. Then, the influences of temperature, porosity and cell size on the effective thermal conductivity of the polyurethane foam are investigated. The results show that the effective thermal conductivity of the polyurethane foams increases with temperature; and the effective thermal conductivity of the polyurethane foams decreases with increasing porosity while increases with the cell size.

Compressive characteristics of closed-cell aluminum foams with different percentages of Er element

In the present study, closed-cell aluminum foams with different percentages of erbium （Er） element were successfully prepared. The distribution and existence form of erbium （Er） element and its effect on the compressive properties of the foams were investigated. Results show that Er uniformly distributes in the cell walls in the forms of Al3Er intermetallic compound and AI-Er solid solutions. Compared with commercially pure aluminum foam, Er-containing foams possess higher micro-hardness, compressive strength and energy absorption capacity due to solid solution strengthening and second phase strengthening effects. Additionally, the amount of Er element should be controlled in the range of 0.10wt.%-0.50wt.% in order to obtain a good combination of compressive strength and energy absorption properties.

Analysis of Reflection Characteristics for Foam Filled Grid Structure

The reflection characteristics of gird structures are calculated by the spatial network method in the case of normal incidence plane electromagnetic wave. The numerical result shows that the grid panels without electromagnetic wave absorbing foams are not ideal. However, the absorbing ability can be achieved as low as -25 dBsm from 8 GHz to 12 GHz when the grid cells are filled with foam absorbers. Also it is noted from computation that the foam filled grid structures with larger cell size, higher and thinner ribs will improve the absorbing abilities, which illustrates that they can be used as the effective light-weight stealth structures for aeronautical application.

广义Riccati展开法及其在foam drainage方程中的应用

应用双曲函数法结合Riccati方程,求得foam drainage方程的精确解.通过这种方法可以得到此方程的新的孤立波解与周期解,并且此方法可以用来求解其它许多的非线性演化方程.

CFD Investigations of Ship Maneuvering in Waves Using naoe-FOAM-SJTU Solver

Ship maneuvering in waves includes the performance of ship resistance, seakeeping, propulsion, and maneuverability. It is a complex hydrodynamic problem with the interaction of many factors. With the purpose of directly predicting the behavior of ship maneuvering in waves, a CFD solver named naoe-FOAM-SJTU is developed by the Computational Marine Hydrodynamics Lab(CMHL) in Shanghai Jiao Tong University. The solver is based on open source platform OpenFOAM and has introduced dynamic overset grid technology to handle complex ship hull-propeller-rudder motion system. Maneuvering control module based on feedback control mechanism is also developed to accurately simulate corresponding motion behavior of free running ship maneuver. Inlet boundary wavemaker and relaxation zone technique is used to generate desired waves. Based on the developed modules, unsteady Reynolds-averaged Navier-Stokes(RANS) computations are carried out for several validation cases of free running ship maneuver in waves including zigzag, turning circle, and course keeping maneuvers. The simulation results are compared with available benchmark data. Ship motions, trajectories, and other maneuvering parameters are consistent with available experimental data, which indicate that the present solver can be suitable and reliable in predicting the performance of ship maneuvering in waves. Flow visualizations, such as free surface elevation, wake flow, vortical structures, are presented to explain the hydrodynamic performance of ship maneuvering in waves. Large flow separation can be observed around propellers and rudders. It is concluded that RANS approach is not accurate enough for predicting ship maneuvering in waves with large flow separations and detached eddy simulation(DES) or large eddy simulation(LES) computations are required to improve the prediction accuracy.

有机模板孔径和烧结温度对SiC泡沫陶瓷结构和性能影响

SiC泡沫陶瓷作为一种新型多孔材料,因其强度高、硬度高、耐腐蚀、耐高温等优异性能,被广泛应用于冶金、石油化工、航空航天、生物医学等领域。以SiC为主要原料,Al_(2)O_(3)为烧结助剂,采用有机模板浸渍法制备了SiC泡沫陶瓷,研究了有机模板孔径和烧结温度对SiC泡沫陶瓷宏微观形貌、相组成、孔隙率及压缩性能的影响。结果表明:随着有机模板孔径由35 ppi增至20 ppi,SiC泡沫陶瓷的孔隙率由48.3%升至75.6%,而抗压强度由1.94 MPa降至0.40 MPa。随着烧结温度由1350℃提高至1500℃,SiC泡沫陶瓷的孔隙率由78.7%降至68.3%,抗压强度先升后降。在1450℃制备的SiC泡沫陶瓷样品抗压强度最高(1.45 MPa),其孔隙率为71.6%,孔结构完整、颗粒堆积紧密,针眼孔洞、裂纹以及脆性方石英相较少。

纤维再生微粉泡沫混凝土的配合比设计及制备研究

为解决再生微粉应用受限问题,提高资源化利用率,分析研究水灰比、发泡剂、掺合料、外加剂及纤维等因素对现有普通泡沫混凝土的影响规律,提出基于再生微粉的微活性和填充性,采用再生微粉部分取代水泥,通过物理发泡法制备纤维再生微粉泡沫混凝土,阐述新型纤维再生微粉泡沫混凝土配合比设计及制备工艺流程。

速泡鲜腐竹加工工艺研究

在传统腐竹加工工艺的基础上,采用冷冻工艺制备速泡鲜腐竹。研究鼓风干燥预处理方式下冷冻时间、冷冻温度对速泡鲜腐竹复水率、泡发时间、感官品质的影响。分析不同加工工艺下腐竹的质构、色泽、泡发时间和复水率,以及炒制、油炸和煮制食用方式下产品的品质特点。结果表明,速泡鲜腐竹的最佳工艺为鼓风干燥温度40℃、干燥时间20 min、冷冻时间8 h、冷冻温度-20℃,该条件下制备的速泡鲜腐竹的水分含量为42.55%,泡发时间为3 min,复水率为58.87%。与市售干腐竹相比,速泡鲜腐竹的泡发时间缩短了90倍,油炸时的吸油率降低48.51%,速泡鲜腐竹无需浸泡,可以直接炒制、油炸和煮制,极大提高了食用的便捷性。

Numerical Simulation of Foaming Processes

The literature model studied in this article describes bubble formation and growth in a highly viscous polymer liquid with support of a gaseous matter dispersed under pressure before foaming. The foam growth is induced by the application of vacuum and mass transport of volatile components dissolved in the polymer liquid. Based on this literature model, aeration processes are calculated for intermediate viscosity and low viscosity biological systems, as they are of interest for biomatter foams, in particular for food foams in industrial processes. At the end of this article, the numerical results are presented and discussed.

烧成温度对钙长石隔热耐火材料显微结构与性能的影响

本工作以矾土水泥与黏土为原料,采用发泡法制备了钙长石隔热耐火材料,通过XRD、SEM和导热仪等分析了烧成温度(1110~1310℃)对钙长石隔热耐火材料显微结构与性能的影响,并研究了该种钙长石隔热耐火材料的合成机理。结果表明:当烧成温度为1110~1160℃时,体系内开始生成钙长石,但原料微颗粒间的反应并不完全,生成的液相含量较少,强度较低;当烧成温度为1210~1260℃时,液相含量增多,钙长石的生成速度加快,强度增大,试样具有较低导热系数;当烧成温度为1310℃时,液相含量迅速增多,线收缩率迅速增大,试样具有较大强度,但体积密度大幅增长,气孔率降低。在1260℃时,制得了体积密度为0.53 g/cm^(3)、气孔率为82.6%、抗折强度为1.15 MPa、耐压强度为1.99 MPa、800℃导热系数为0.101 W/(m·K)的钙长石隔热耐火材料。

KOH添加方式对煤基活性泡沫炭电化学性能的影响

以强黏性炼焦煤为原料,经常压自发泡法制得的煤基泡沫炭(NCF)为碳基底,KOH为活化剂,采用机械混合、水溶液浸渍、乙醇浸渍三种不同的方式制备煤基活性泡沫炭(HPCs),并将其用作双电层电容器的电极材料,研究了KOH添加方式对其微观结构和电化学性能的影响。结果表明,KOH分散度和附着性对煤基活性泡沫炭孔隙结构的生成、晶体结构、表面化学性质以及电化学性能有显著影响。煤基泡沫炭本身具有三维连通泡孔结构,有利于活化剂(KOH)深入材料的泡孔内部并为其提供大量附着位点,增大活化剂与碳基体的接触面积进而发生高效的活化。KOH水溶液的流动性较好,可以使K+更有效地穿插在NCF的泡孔结构中,在活化过程中作用于缺陷部位,在碳基体内部基质上产生更多的微孔以及介孔结构,有效地放大了活化效果。KOH水溶液浸渍泡沫炭材料制得的ACF-W样品拥有最高的比表面积(3098.35 m^(2)/g)、总孔体积(1.68 cm^(3)/g)、介孔体积比(59.13%),将其用作电极材料表现出优异的比电容(310 F/g)以及循环稳定性。

高熔体强度聚丙烯制备及其发泡材料功能化

普通聚丙烯(PP)过低的熔体强度(MS)会制约PP发泡技术发展,高熔体强度聚丙烯(HMSPP)是在聚合过程中引入支链而制备的长支链聚丙烯,长支链结构能改变普通PP的应变软化效应,使HMSPP具有热稳定性好、加工温度范围宽、抗熔垂性好等特征,拓宽PP发泡温度范围的同时改善PP泡沫性能。本文介绍了HMSPP的概念、特征及表征方法,列举了HMSPP国内外主要研究机构及产品,对比了HMSPP的制备方法(包括反应挤出法、聚合法、辐照制备法、交联制备法、共混改性法等)的优缺点,综述了HMSPP的发泡方法(包括挤出发泡、模压发泡、釜压发泡、注射发泡、吹塑发泡等),介绍了HMSPP的应用及功能化(如隔声、隔热、阻燃、吸附等),最后对HMSPP未来的研究方向和应用进行了展望,鉴于我国高端HMSPP研究起步较晚,相关科研机构需加大研发力度,开发高性能附加值的HMSPP产品,拓宽HMSPP的应用领域,提高市场竞争力。

发泡聚乙烯最大加速度-静应力曲线快速获取方法研究

目的研究快速、准确预测最大加速度-静应力曲线的方法。方法首先利用落锤冲击试验机获取了5个不同高度下,5种不同厚度的发泡聚乙烯的最大加速度-静应力曲线。在此基础上,分析对比文中3种不同的改进拟合法与已有的动应力与动能量多项式拟合法的区别。结果研究发现,当不区分高度的情况下,以最大加速度因子为函数值,以跌落高度、衬垫厚度、静应力为变量进行拟合时,其代表预测精度R^(2)的平均为0.835,相比动应力与动能量多项式拟合法的0.2996要高。但曲线右侧的预测精度偏低。引入以静应力为变量的多项式作为修正因子后,R^(2)的平均值为0.934。预测精度有所提高,右侧的预测偏差减小,但仍存在。在区分高度的情况下,以带有修正因子的公式进行预测时,R^(2)的平均值为0.984,曲线向右侧预测偏差逐渐增大的现象明显改善。结论区分高度情况下,利用带修正因子的预测公式可以快速且较准确地预测最大加速度-静应力曲线,可以为冲击防护设计及相关软件的开发提供一定的帮助。

基于LBM的泡沫金属与翅片相变储能系统性能对比分析

为了研究翅片和泡沫金属铜对相变储能系统性能的影响,使用四参数随机生长法(QSGS)构建了孔隙密度(PPI)分别为20PPI、30PPI的泡沫铜复合相变材料模型,并构建了等铜质量的翅片相变材料模型。在此基础上,采用格子玻尔兹曼(LBM)数值模拟方法对相变材料(PCM)的储/放热过程进行了数值模拟,基于努塞尔数、液相率、PCM流动速度、PCM熔化/凝固时间对比分析了添加翅片以及添加泡沫金属结构对相变材料换热性能的影响。结果表明,在储热过程中,由于泡沫金属的存在会抑制熔化过程中对流换热的发展,双翅片结构的努塞尔数高于泡沫金属结构,熔化时间更短,相比于20PPI、30PPI泡沫铜复合相变材料分别缩短了28.55%、17.5%;在放热过程中,泡沫金属的存在会增加热传导面积,泡沫金属结构的凝固速度高于翅片结构,30PPI泡沫金属结构的凝固时间相比于翅片、20PPI泡沫铜复合相变材料分别缩短了65.80%、20.24%。综合考虑储放热两个过程,30PPI泡沫金属结构的总储放热时间最短,相比于翅片、20PPI泡沫铜复合相变材料分别缩短了27.81%、15.32%。在耗费相同金属材料的条件下,采用泡沫结构是更为有效的提升储能效率的手段。

Numerical Calculation of Transient Flow of Polymer Foam in Porous Media

Based on the mathematical model of one dimension transient flow of the polymer foam in porous media, the numerical calculation method of the flow mentioned above by using the finite difference method is given. Through the experiments of one dimension transient flow of HPAM (Hydrolytic Polyacrylamide) foam in the artificial sandstone core, the HPAM foam generation and coalescence coefficient of the mathematical model mentioned above are determined. The profiles of the liquid phase saturation, the pressure drop and the number density of one dimension transient flow of HPAM foam with the dimensionless time in artificial sandstone core are numerically calculated and analyzed by using the numerical calculation method.

高钙铁尾矿对多孔陶瓷烧结温度和性能的影响

为促进矿业固废铁尾矿的高值化利用,以高钙铁尾矿作为主要原料,高岭土为黏结剂,石英作为骨料,碳化硅为发泡剂,采用“注浆成型-直接发泡法”制备高孔隙率铁尾矿多孔陶瓷,并通过测试多孔陶瓷孔隙率、孔径分布、体积密度和抗压强度,研究铁尾矿用量对多孔陶瓷烧结温度及性能结构的影响。结果表明,高钙铁尾矿可作为助熔剂使用,在原料配比为40%铁尾矿,20%高岭土、40%石英,外加0.3%碳化硅,烧结温度在1160~1170℃的条件下所制备的多孔陶瓷各项性能最优,其体积密度密度为0.38~0.46 g/cm^(3),气孔率高达80.84%~83.5%,平均孔径为0.33~0.88 mm,抗压强度为1.95~3.28 MPa。微观分析表明,铁尾矿内的方解石高温下分解产生的CaO可以与原料中的SiO_(2)反应生成钙长石,并大幅度降低材料的烧结温度和液相黏度,同时铁尾矿中的方解石和Fe_(2)O_(3)可以促进气泡的增长,有利于进一步提高气孔率。

环境友好生物质材料改性及发泡方法的研究进展

主要介绍了纤维素、木质素、淀粉及壳聚糖4种生物质材料,针对这4种生物质材料进行改性,赋予了其各种性能,总结了3种可降解生物质材料的发泡方法,包括超临界CO_(2)发泡、冷冻干燥发泡和挤出发泡,并对未来可降解生物质材料在包装、建筑及医疗行业的应用做出了详细综述。

改良DSS法制作稳定泡沫的效果评价

目的:对双注射器系统(double-syringe system,DSS)进行改良,使之能够制作出更稳定的硬化剂泡沫。方法:分别用经典DSS方法和改良DSS方法制备1%聚多卡醇(polidocanol,POL)泡沫。在改良DSS方法中,用自制弹性气囊替代DSS方法中的一个注射器。改良DSS方法制备POL泡沫过程如下,先用注射器抽取2 mL POL液体,再抽取8 mL空气;之后将注射器与连有自制气囊的三通直线连接,反复推拉注射器20次,产生泡沫。采用泡沫半衰期(foam half-time,FHT)和显微镜观察,比较2种泡沫稳定性及均一性。检测改良DSS方法制备中泡沫体积的变化,比较扭转三通角度后,改良DSS方法制备泡沫的质量。采用GraphPad Prism 8.0软件包对于数据进行统计学分析。结果:用自制弹性气囊替代经典DSS方法中单个注射器的改良DSS方法,能够制备出半衰期更长、微泡更均一的泡沫,可能与泡沫制备过程中的体积压缩有关。同时,改良DSS方法可以通过扭转三通角度,进一步提升泡沫质量。结论:改良DSS方法用弹性气囊替代经典DSS方法中的单个注射器,能够产生更稳定的泡沫。

空穴效应下泡沫金属复合相变材料热性能数值模拟

在三维泡沫金属复合相变材料(PCM)基础上,构建了随机分布空穴模型,采用多松弛时间格子Boltzmann方法,从孔隙尺度分析了不同空穴体积分数、分布位置及泡沫金属与PCM导热系数比下的空穴效应.结果表明,随着空穴体积分数的增加,减缓了复合PCM的传热速度,并降低了潜热储能的能力.在Fourier数Fo=0.7时刻下,当空穴体积分数分别为2.4%,7.6%和11.7%时,相较于无空穴情况下的储热量分别减少了3.2%,9.0%和13.0%.当体积分数为3%的空穴集中在热壁面侧时,其对复合PCM熔化过程的阻碍作用最显著,此时空穴层相当于绝热层,使复合PCM的整体熔化时间延长了6.1%.为削弱空穴效应,可选择导热系数比超过100的泡沫金属骨架来提高其在传热中的主导作用.