尼龙—6聚合反应器内部结构的冷模研究

本文研究ＶＫ管、尼龙６聚合反应器内挡板结构对高粘流体混合质量的评价问题。通过测定ＲＴＤ、空间混合相关系数以及对混合流场的直接观察，对多孔板型、换向器型以及抛物线型３种内插件的混合效果作出了定量和直观的综合评价，并能估计出混合效果的方向性。同时还了利用Ｎ．Ｓ．方程求出流动数值解的某些结果，理论计算和实验所得结构相符。     

速度流型对微混合器混合效果的影响

微流控芯片是“芯片实验室”发展的重点,微混合器是微流控芯片的重要作用形式,在微尺寸下获得高效混合是重要的研究方向．采用Fluent软件对T型管两液流混合过程进行了数值模拟,对三种典型速度流型,即抛物线型、塞状型和凹面型速度流型条件下的混合效果进行了比较分析、数值模拟和理论分析表明：流速以及流型对混合效果具有很大的影响,抛物线型的混合效果最好;利用泵驱动系统比电渗驱动系统更有利于混合．     

下一代旋转式光编码器

传感器通过混音，提升了音响的性能和灵活性 计算机和元件技术的发展为专业声学设备带来了日新月异的变化．随着数字混音技术的出现，音响的混音成为了现实。其功能大大增强。推钮、旋钮和按钮一起使用．可以控制混合音效．包括调整声道、制造效果、调节以及混合多种数字和模拟声音输入。使用旋转式光学编码器．可以增强工作效果．实现定制化控制．通过与屏幕菜单的交互调节不同的声音效果。     

基于混合坐标系的FDM型3D打印机研制

传统FDM（fused deposition molding，熔融沉积成型）型3D打印机在打印倒体件的过程中需设置辅助支撑结构，打印完成后去除支撑结构，这会导致成型件的精度降低。为解决传统FDM型3D打印机存在的问题，设计了一种基于混合坐标系的FDM型3D打印机。将基于笛卡尔坐标系的运动方式转换为基于拟球坐标系的运动方式，由X-Z平面内的旋转运动、X-Y平面内的旋转运动和Z轴方向的直线运动组合成拟球坐标系内的运动，达到无支撑3D打印的目的。介绍了基于混合坐标系的FDM型3D打印机控制系统的硬件和软件设计。用传统FDM型和基于混合坐标系的FDM型3D打印机进行打印实验并作对比，结果表明在同等级精度硬件配置的情况下，基于混合坐标系的FDM型3D打印机可以实现更高的打印精度。基于混合坐标系的FDM型3D打印机创新性强、造价低，拥有自主知识产权，具有广阔的市场前景。     

铀矿爆破增渗改造的爆生气体返排规律研究

为了分析爆破后裂隙内气体的返排规律，基于气液两相流规律，借助相场方法对两相流界面进行追踪，模拟了驱替压差、裂隙开度和接触角等对裂隙内气体返排过程中水气界面形态和位置的时空演化规律；通过响应面法，分析了各影响因素的显著性，最终建立了气体返排效果评价流程。研究表明，单因素分析裂隙内气体返排效率同驱替压差、裂隙开度成正比。通过多因素分析，以气体排出速率作为评价指标，建立了CO₂气体返排效果评价流程。该研究内容对低渗砂岩型铀矿的爆破增渗后气体返排工艺具有一定的理论参考和现场指导意义。     

可以薄膜化的抗菌性材料

可以薄膜化的抗菌性材料日本开发电子材料的川角技术研究所，通过向精细陶瓷内添加银，开发出了具有防菌防腐性能的抗菌性材料。据日本北里大学试验评价，这种新材料除对大肠杆菌或绿脓菌有抗菌效果外，对耐药性黄色葡萄球菌也具有强力的抗菌效果，而且薄膜容易薄化等混合...     

多层混合填料型低温蓄冷器的数值分析

首次建立了较完善的液氮温区多层混合填料型低温蓄冷器的数值模拟方法,模型中考虑了工作过程中的传热,蓄冷器内空隙率存在以及工质的实际气体性质等多种实际因素。运用数值模拟方法,详细地研究了常用蓄冷填料如Ｐｂ,Ｅｒ３Ｎｉ,ＥｒＮｉ２,ＥｒＮｉ,ＥｒＮｉ０．９Ｃｏ０．１等的不同组合对制冷效果的影响,提出了不同填料的最佳组合确定原则,为合理有效地设计高性能液氦温区低温蓄冷器提供了依据。     

某混合动力汽车非稳态车内声品质评价研究

针对某混合动力汽车非稳态工况下的车内声品质评价进行研究。采集该车内不同位置、不同驱动模式以及不同车速情况下的车内噪声样本,对不同的非稳态工况进行客观参量分析,得出电机单独驱动模式下可以用尖锐度评价非稳态车内声品质、混合驱动与发动机单独驱动模式下可以用响度评价非稳态车内声品质的结论。基于BP神经网络模型,进行基于心理声学客观参量与临界频率带解析小波分解的非稳态车内声品质评价,预测结果表明后者的预测效果优于前者,且稳定性较高。     

混合导体透氧膜材料的开发及应用

介绍开发的混合导体透氧膜材料ZrO2掺杂的SrFe0.6Co0．4O3-δ类钙钛矿型氧化物及Sr(Co，Fe，Zr)O3-δ系列钙钛矿型氧化物的晶体结构、氧渗透性能、稳定性，以及应用于甲烷部分氧化制合成气膜反应器的性能，并就今后研究开发方向作了探讨．     

工装篮烘干筒内硅料颗粒混合过程的数值模拟

硅料的烘干是全自动超声波清洗机在生产过程中最重要的环节，研究该环节工装篮烘干筒内硅料颗粒的烘干过程对烘干装置节能和工装篮烘干筒结构优化具有重要意义。通过DEM离散软件，在搅棒形状、搅棒数、烘干筒外框转速、颗粒状硅料填充率等影响因素下对工装篮烘干筒内颗粒状硅料的混合过程进行数值模拟和分析。通过单因素和多因素正交实验模拟及Lacey指数M对混合均匀性进行定量分析，得到各参数最佳工况。结果表明：与其他形状的搅棒相比，长方体搅棒的烘干筒内颗粒混合效果最好；当搅棒数为6时，混合程度达到最佳值，颗粒群混合效果随着填充率的增加而下降。与填充率为31.73%和41.40%相比，填充率为23.60%时对流混合作用影响最强，混合效果更好。烘干筒转速为8.91 rad/s时，可以提高硅料颗粒混合的均匀性和质量，从而提高混合效率。通过正交分析得出，影响因素中烘干筒外框转速影响最大，其次为颗粒填充率、搅棒数、搅棒形状。     

Rate measurements by the pulsed-accelerated-flow method

A pulsed-accelerated-flow spectrophotometer with UV-visible capability is described that permits measurement of pseudo-first-order rate constants as large as 500?000 s(-)(1) (t(1/2) = 1.4 μs). Chemical rate processes are resolved from physical mixing rate processes by variation of flow velocities under conditions of turbulent flow. Two mixing processes are found in the mixing/observation tube. One mixing rate constant, valid for the full length of the tube, is directly proportional to the flow velocity. The other mixing behavior, proportional to the square of the flow velocity, is found only in the immediate vicinity of the 10 inlet reactant streams that collide with one another in the middle of the observation tube. Contributions from the latter mixing become more important for very fast reactions that take place close to the inlet jets. These mixing models and improved signal/noise permit the measurement of rate constants for very fast reactions. Applications of the PAF method to electron-transfer, proton-transfer, hydrolysis, and non-metal redox reactions are reported for pseudo-first-order and second-order reactions.     

Factors affecting properties of mechanically-formed building units

The physical and mechanical properties of mechanically-pressed clay building units, whether solid or perforated, are largely improved by deairing. Die-laminations are lessened. Moreover, deairing provides always units of developed strengths. Prepugging, using birollers machinery, proves effective only in rubbing and well mixing the clay mixes before extrusion. In solid machine-pressed building units the direction of extrusion shows the relatively highest value when tested for strength. On the other hand, for the perforated equivalents, this depends, among other factors, on the load-bearing area to which the pressure is applied. However, the size and shape of perforations through the perforated units largely affect the mechanical properties of the latter.     

多孔式翅片传热与流阻特性分析

采用CFD数值模拟技术,研究了多孔式翅片传热与流阻特性,重点分析了不同孔口因素对多孔式翅片传热与流阻的影响.研究结果表明:随着孔隙率增加,多孔式翅片流阻增大,但其传热并未明显提升.同一孔隙率下,翅片传热与流阻随孔径减少而提升.开孔方式呈错列布置的流阻与传热性能高于孔口呈并行布置的情况.开孔结构对多孔式翅片传热性能影响较...     

均匀流直通穿孔管消声器声学特性预测的有限元法

将有限元法应用于预测有均匀流存在时直通穿孔管消声器的声学特性,推导了考虑运流效应的有限元法计算公式,并给出了声学特性的计算方法和数值实施过程。传递损失数值计算结果表明,随着气流马赫数的增加,消声器中高频的消声量有所增加。为精确预测直通穿孔管消声器的声学特性,流速对消声器内声传播的影响应加以考虑。     

多穿孔管板阻性消声器的声学特性研究

应用包含高阶模态声波的二维解析法研究多穿孔管板阻性消声器的声学性能,消声器传递损失的计算结果和实验结果吻合良好.分析了穿孔率和吸声材料的流阻率对阻性消声器声学性能的影响,并且研究了具有组合式阻抗及组合流阻率吸声材料的多穿孔管板消声器的声学特性.结果表明:不同类型的组合式阻抗及组合流阻率的吸声材料对消声器在不同频段的消声性能产生一定影响.     

Effects of particle size and region width on the mixing and dispersion of pebbles in two-region pebble bed

Granular systems and their mixing processes are widely used in various industries. The effects of size ratio and region width on the mixing and dispersion of pebbles in the two-region pebble bed are studied by discrete element method (DEM). The particle-scale mixing index (PSMI) and mixing entropy are used to quantify the particle mixing process. A similarity of mixing under different discharge rates is found after a stable two-region distribution structure is established. From qualitative observation and quantitative analysis, the mixing region is complicated in shape for the cases with greater particle size ratios. There is an increasing tendency of PSMI for two-region pebble bed when the region ratio or size ratio rises. The size ratio has greater effects on the mixing and dispersion of pebble than the region ratio, since the occupied volumes and entropies in the mixing region in the relatively steady state are more strongly affected by the size ratio rather than by the region ratio. As particles in the side regions can be easily driven by large ones, the stagnant region will decrease greatly when large size particles flow in the central region.     

多层吸声材料吸声系数的理论计算

目前由穿孔板和空腔以及多孔吸声材料组成的多层吸声材料的吸声系数还没有理论方法求解,本文提出了一种多层吸声材料吸声系数的理论解法。首先,对于由穿孔板和空腔或穿孔板和吸声材料组成的多层吸声材料,用等效声电类比图求出声阻抗,从而求得吸声系数;然后,对由穿孔板和空腔以及吸声材料组成的多层吸声材料,利用递推方法求得声阻抗,从而求得吸声系数。最后,对由不同层材料组成的多层吸声材料的吸声系数进行了理论计算,并与实验结果进行了对比,结果表明：用该方法理论计算多层吸声材料的吸声系数是可行的。     

切向流条件下穿孔板声学性能脉冲法测量技术

采用脉冲测量法,通过在管道内生成波形良好的可控脉冲,实现切向流条件下的穿孔板声学性能宽频带测量。研究切向流对穿孔板声阻抗的影响特征。研究结果表明,在1 500 Hz以下频段,穿孔板的声阻率随流速增大,而在1 500~4 000 Hz频段,声阻率随流速减小;切向流条件下的共振峰向高频偏移,吸声频带加宽。     

非均匀流条件下穿孔管消声器传递损失计算方法与特性分析

实际应用中的消声器通常具有比较复杂的内部结构,其内部流体速度分布不均匀,而且消声器内部的回流管路和穿孔元件使得消声器内部的流体流动更加复杂,其消声性能不可避免地受到流体流动的影响。为了计算非均匀流条件下穿孔管消声器的传递损失,应用计算流体力学(Computational Fluid Dynamics, CFD)软件FLUENT计算消声器内部的流场,然后将流体属性通过网格映射的方式转移到LMS Virtual Lab声学有限元模型中,并且选用不同的穿孔阻抗模型计算消声器的传递损失,计算结果与实验测量结果进行了比较。文章对消声器内部流场的流动特征也做了仔细地分析,并研究了气体流速对消声器传递损失的影响,随着气体流速的增加,消声器的传递损失会增大,共振峰的峰值会减小。     

Opening of Perforated Folding Cartons: From the Field to Testing

This study demonstrates how a human‐hand opening process for a perforated folding carton can be mapped into a path for testing. A field observation was conducted to visually record opening patterns by an observation group. The most representative opening pattern was then repeated by another observation group in the laboratory, and the resulting opening pattern and movements were captured and mapped mathematically via Matlab. The opening speeds were calculated based on opening path that is used to compare the testing machine. A fixture attempting to mirror the opening path was developed for perforated folding cartons to be tested by using tensile testing machine. The study suggested that the process, involving the identifying opening pattern, guided test and fixture equipped testing, can be applied to replication of human‐packaging interaction. Copyright © 2016 John Wiley & Sons, Ltd.