Analysis of pressure and heat distribution in a dilating or contracting filter chamber with two outlets using multivariate spectral quasilinearization method

The development of efficient filters is an essential part of industrial machinery design, specifically to increase the lifespan of a machine. In the filter chamber design considered in this study, the magnetic material is placed along the horizontal surface of the filter chamber. The inside of the filter chamber is layered with a porous material to restrict the outflow of unwanted particles. This study aims to investigate the flow, pressure, and heat distribution in a dilating or contracting filter chamber with two outlets driven by injection through a permeable surface. The proposed model of the fluid dynamics within the filter chamber follows the conservation equations in the form of partial differential equations. The model equations are further reduced to a steady case through Lie's symmetry group of transformation. They are then solved using a multivariate spectral-based quasilinearization method on the Chebyshev–Gauss–Lobatto nodes. Insights and analyses of the thermophysical parameters that drive optimal outflow during the filtration process are provided through the graphs of the numerical solutions of the differential equations. We find, among other results, that expansion of the filter chamber leads to an overall decrease in internal pressure and an increase in heat distribution inside the filter chamber. The results also show that shrinking the filter chamber increases the internal momentum inside the filter, which leads to more outflow of filtrates.     

基于数值模拟的挤压参数对AZ91镁合金管转角焊合室分流挤压焊合压力的影响规律研究

提出了一种镁合金管材转角焊合室分流挤压新工艺，该工艺可在有效延长焊合室长度和焊合时间前提下保证舌针刚度，从而保证管材尺寸精度，并且可通过转角剪切变形机制增加预焊合金属变形量和动态再结晶程度，从而有利于提高管材性能和焊缝焊合性能。利用有限元法揭示了转角焊合室分流挤压成形过程中金属的流动特征，应变分布特征和焊合室内的静水压力分布特征。结果表明，整个挤压过程无金属折叠，从而保证管材的表面质量；流经转角后预焊合金属变形量明显增加，有利于提高管材质量和焊缝质量。最后，研究揭示了坯料初始温度，挤压速度和模具转角对焊合室内静水压力的影响规律。结果表明，随着挤压速度的增加和模具转角的增大，转角焊合室内静水压力增大；随着坯料预热温度的增加，转角焊合室内静水压力呈先增大后减小的趋势。     

中压进汽腔的流场数值模拟比较

通过数值模拟计算,对中压对称进汽和切向进汽两种结构的流场进行了分析比较,结果表明,单一切向进汽腔的总压损失更小,出口汽流角的周向分布均匀度更好。更进一步,为整体评估中压进汽腔的流场以及对叶片级的流动影响,对中压进汽腔及第1级叶片的整体流体域流场情况进行了分析比较,结果表明,采用大几何角静叶的切向进汽腔气动性能最优;当采取切向进汽腔时,需合理选择第1级静叶几何角并耦合计算,才能实现进汽腔的气动优化。     

张庄铁矿高阶段矿房切割天井施工工艺试验

张庄铁矿设计采矿方法为大直径深孔阶段空场嗣后充填法。为了最大化发挥采矿设备性能，降低采切工程量，提高回采效率，通过实施一系列技术攻关，实现了将采矿阶段高度由原来的60 m提高到90 m。而作为最初爆破回采的自由面及爆破补偿空间，切割天井施工工艺为影响高阶段矿房爆破回采效果的关键因素，施工质量的优劣，直接影响矿房爆破回采生产作业能否顺利进行，而二次处理在增加施工成本的同时将带来安全隐患。张庄铁矿在面临可参考的成熟经验较少的情况下，结合现场可用的作业条件采取了对比试验的方法，在安全、技术及经济多方面综合分析比较下，确定了最终方案，为张庄铁矿安全稳定生产奠定了基础，同时研究成果可为大型地下矿山生产实践提供一定的参考。     

The control of paracetamol particle size and surface morphology through crystallisation in a spray dryer

The parameters governing the crystallisation of paracetamol using various conventional techniques has been extensively studied, however the factors influencing the drug crystallisation using spray drying is not as well understood. The aim of this work was to investigate the crystallisation of an active pharmaceutical ingredient through evaporative crystallisation using a spray dryer to study the physicochemical properties of the drug and to use semi-empirical equations to gain insight into the morphology and particle size of the dried powder. Paracetamol solutions were spray dried at various inlet temperatures ranging from 60 °C to 120 °C and also from a series of inlet feed solvent compositions ranging from 50/50% v/v ethanol/water to 100% ethanol and solid-state characterisation was done. The size and morphology of the dried materials were altered with a change in spray drying parameters, with an increase in inlet temperature leading to an increase in particle Sauter mean diameter (from 3.0 to 4.4 µm) and a decrease in the particle size with an increase in ethanol concentration in the feed (from 4.6 to 4.4 µm) as a result of changes in particle density and atomised droplet size. The morphology of the dried particles consisted of agglomerates of individual crystallites bound together into larger semi-spherical agglomerates with a higher tendency for particles having crystalline ridges to form at higher ethanol concentrations of the feed.     

煤矿井下避难硐室系统的构建与应用分析

为进一步减少煤矿事故发生后的人员伤亡、财产损失，在分析国内外煤矿井下避难系统发展的基础上，以何家塔煤矿井下避难硐室系统的构建设计与应用为例，详细介绍了井下避难硐室系统的分类、结构构成、功能需求和配套设施等，并通过紧急避险疏散时间的校验计算，提出避难硐室距离采掘工作面以不超过1 000 m为宜，且应按照“地面最安全，先逃生后避险”原则进行避险救援，为国内其他矿井避难硐室的构建应用和相关标准的制定提供了参考。     

Healing Pattern Analysis for Dental Implants Using the Mechano-Regulatory Tissue Differentiation Model

(1) Background: Our aim is to reveal the influence of the geometry designs on biophysical stimuli and healing patterns. The design guidelines for dental implants can then be provided. (2) Methods: A two-dimensional axisymmetric finite element model was developed based on mechano-regulatory algorithm. The history of tissue differentiation around eight selected implants can be predicted. The performance of the implants was evaluated by bone area (BA), bone-implant contact (BIC); (3) Results: The predicted healing patterns have very good agreement with the experimental observation. Many features observed in literature, such as soft tissues covering on the bone-implant interface; crestal bone loss; the location of bone resorption bumps, were reproduced by the model and explained by analyzing the solid and fluid biophysical stimuli and (4) Conclusions: The results suggested the suitable depth, the steeper slope of the upper flanks, and flat roots of healing chambers can improve the bone ingrowth and osseointegration. The mechanism related to solid and fluid biophysical stimuli were revealed. In addition, the model developed here is efficient, accurate and ready to extend to any geometry of dental implants. It has potential to be used as a clinical application for instant prediction/evaluation of the performance of dental implants.     

A test method for evaluating the thermal environment of underground coal mine refuge alternatives

Since 2009, the Mine Safety and Health Administration(MSHA) has required mines to install refuge alternatives(RAs) in underground coal mines. One of the biggest concerns with occupied RAs is the possible severity of the resulting thermal environment. In 30 CFR 7.504, the maximum allowable apparent temperature(AT) for an occupied RA is specified as 35 °C(95 °F). Manufacturers must conduct heat/humidity tests to demonstrate that their RAs meet the 35 °C(95 °F) AT limit. For these tests, heat input devices are used to input the metabolic heat of actual miners. A wide variety of test methods, sensors, and heat input devices could be used when conducting such tests. Since 2012, the National Institute for Occupational Safety and Health(NIOSH) has conducted over thirty 96-hour heat/humidity tests on four different RAs. This paper discusses the test equipment and procedures used during these investigations. This information is useful for RA manufacturers conducting RA heat/humidity tests, for other researchers investigating RA heat/humidity buildup, and for those who need to assess the thermal environment of any confined space where people may be trapped or are seeking refuge.     

基于CFD⁃DEM的水下切粒装置水室内颗粒流动过程数值模拟

基于CFD?DEM耦合方法，研究了颗粒在水室内的流动状态，分析了不同刀盘转速、粒子水通入量和水室出口角度对造粒过程的影响，发现提高刀盘转速、增加粒子水通入量和水室出口倾斜一定的角度都有利于水室内颗粒的排出。进一步研究了颗粒与碎屑在水室内的流动，发现在水室出口处二者的流动基本呈现出一定的分离角度。     

流量脉动对燃油喷嘴雾化过程影响的实验研究

针对航空发动机燃烧室中存在的燃油流量脉动问题开展实验研究,设计并搭建了燃油喷嘴流量脉动激光可视化实验台,在等流量条件下利用高频激光粒子图像速度仪(High Speed Particle Image Velocimetry, PIV)分析燃油脉动频率变化对喷嘴雾化特性影响。实验结果表明:流量脉动促进了液膜表面的发展及液膜的破碎,对喷嘴的雾化产生积极的影响;喷嘴下游带状液膜区的发展和液滴的瞬态速度与喷嘴的流量脉动频率具有一致性;液滴的瞬态速度脉动幅值受脉动频率影响,在50 Hz时存在极大值。