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关键词： Medical visualizations   aneurysms   blood flow   parametrization   classification  

摘要： We present a Cerebral Aneurysm Vortex Classification (CAVOCLA) that allows to classify blood flow in cerebral aneurysms. Medical studies assume a strong relation between the progression and rupture of aneurysms and flow patterns. To understand how flow patterns impact the vessel morphology, they are manually classified according to predefined classes. However, manual classifications are time-consuming and exhibit a high inter-observer variability. In contrast, our approach is more objective and faster than manual methods. The classification of integral lines, representing steady or unsteady blood flow, is based on a mapping of the aneurysm surface to a hemisphere by calculating polar-based coordinates. The lines are clustered and for each cluster a representative is calculated. Then, the polar-based coordinates are transformed to the representative as basis for the classification. Classes are based on the flow complexity. The classification results are presented by a detail-on-demand approach using a visual transition from the representative over an enclosing surface to the associated lines. Based on seven representative datasets, we conduct an informal interview with five domain experts to evaluate the system. They confirmed that CAVOCLA allows for a robust classification of intra-aneurysmal flow patterns. The detail-on-demand visualization enables an efficient exploration and interpretation of flow patterns.

关键词： Flow patterns   Pneumatic conveying   Classification model   Machine learning   Signal analysis  

摘要： Dense-phase pneumatic conveying of pulverized coal experiments with superficial gas velocity ranged from 0.59 m s(-1) to 2.43 m s(-1) were carried out on the self-established 50 mm I.D. industrial pipe facility. The fluctuations of pressure, solid velocity, solid concentration and the average cross-section concentration were analyzed in terms of relative standard deviation (RSD), powder spectrum density analysis (PSD) and wavelet analysis. Further, a novel classification model of flow patterns for dense-phase pneumatic conveying of pulverized coal was proposed. The model was based on the relationships among superficial gas velocity, particle velocity and solid concentration. K-means method, std method, k-medoids and CART method were compared firstly and then the k-means method and CART method were introduced to classify the flow patterns. The bagged trees method and 5-fold cross-validation were used to train the classification model, whose accuracy was 95.2% and 91.9%. It meant that the new classification model was able to classify the flow patterns in the pneumatic conveying of pulverized coal. In the end, the change of flow patterns and transmission of flow patterns were explained by the wavelet analysis method from the aspects of different signal scales and power spectrum analysis. The new classification model will be of great help for the industry to have a better understanding on the classification and control of flow patterns. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

关键词： Fluidized beds  

摘要： This article discusses a simulation study performed to investigate the effect of particle collision on inter-particle and gas-solid heat transfer processes, and other related bed flow characteristics. The effect of particle elasticity is presented using different values of the particle-particle coefficient of restitution. The simulation study was carried out using a two-dimensional model of a fluidized bed reactor incorporated to ANSYS Fluent 16.2 software. Two different materials, steel beads and sand particles, were used as the bed material fluidized by air. The simulation results are compared to those from previous studies on fluidized bed reactors containing a single bed material. The coefficient of restitution affected the bed hydrodynamics. Specifically, an increasing coefficient of restitution resulted in an increasing bed pressure drop and decreasing void fraction, granular temperature, particle velocity, and collision frequency. Conversely, increasing the particle coefficient of restitution resulted in decreasing the particle-particle heat exchange coefficient and the gas-particle heat transfer coefficient. The gas-particle heat transfer coefficient for sand particles was higher than that for steel beads. The effect of the coefficient of restitution on the flow characteristics from a binary mixture bed was quite similar to those of single material beds found in previous studies. This study demonstrated that the restitution coefficient clearly affected both the particle-particle and gas-particle heat transfer processes.

摘要： A new instrument, the High-speed Particle Phase Discriminator (PPD-HS), developed at the University of Hertfordshire, for sizing individual cloud hydrometeors and determining their phase is described herein. PPD-HS performs an in situ analysis of the spatial intensity distribution of near-forward scattered light for individual hydrometeors yielding shape properties. Discrimination of spherical and aspherical particles is based on an analysis of the symmetry of the recorded scattering patterns. Scattering patterns are collected onto two linear detector arrays, reducing the complete 2-D scattering pattern to scattered light intensities captured onto two linear, one-dimensional strips of light sensitive pixels. Using this reduced scattering information, we calculate symmetry indicators that are used for particle shape and ultimately phase analysis. This reduction of information allows for detection rates of a few hundred particles per second. Here, we present a comprehensive analysis of instrument performance using both spherical and aspherical particles generated in a well-controlled laboratory setting using a vibrating orifice aerosol generator (VOAG) and covering a size range of approximately 3-32 mu m. We use supervised machine learning to train a random forest model on the VOAG data sets that can be used to classify any particles detected by PPD-HS. Classification results show that the PPD-HS can successfully discriminate between spherical and aspherical particles, with misclassification below 5% for diameters > 3 mu m. This phase discrimination method is subsequently applied to classify simulated cloud particles produced in a continuous flow diffusion chamber setup. We report observations of small, near-spherical ice crystals at early stages of the ice nucleation experiments, where shape analysis fails to correctly determine the particle phase. Nevertheless, in the case of simultaneous presence of cloud droplets and ice crystals, the introduced particle shape ind

关键词： Annular-blade distributor   Bed pressure drop   Distributor pressure drop   Heat transfer coefficient   Immersed heater   Swirling fluidized bed  

摘要： The present work investigates the heat transfer between the immersed heater and bed and hydrodynamics of the bed in swirling fluidized bed. The heat transfer process and bed hydrodynamics characteristics for swirling fluidized bed reactor (SFBR) were compared to those of conventional fluidized bed reactor (CFBR). Then the influence of particle diameter on the bed flow characteristics and heat transfer process in SFBR were studied. The heat transfer coefficient was calculated at different superficial air velocities, radial positions, and bed heights. Compared to a CFBR, the bed pressure drop and distributor pressure drop for SFBR were lower, that characterizes swirling bed reactor. The heat transfer coefficient of SFBR was higher than the corresponding of CFBR at lower portion of the bed and it was lower at the upper portion of the bed for all radial positions and for all air superficial velocities. Increasing particle diameter in SFBR resulted in decreasing both the heat transfer coefficient and bed pressure drop.

关键词： Dual fluidized bed   Hydrodynamic model   Mixed particles   Pressure distribution  

摘要： Biomass gasification in a dual fluidized bed has been regarded as one of the most promising technologies. The hydrodynamics play a vital role in determining the performance of a dual fluidized bed (DFB) system. In this study, based upon the solid-gas two phase theory, and pressure and mass balances, a hydrodynamic model for the DFB system was developed. The model parameters of mixed particles (rice husk and quartz sand) were fitted using the homogeneous and phase-separated particles model in order to improve the accuracy of predicted results. It was found that the predicted results were in reasonable agreement with the experimental results for the pressure drop, pressure distribution and circulation flow rate of the cold model of the DFB system. Which provides guidance for the operation and design of DFB gasifier equipment. (C) 2019 Elsevier B.V. All rights reserved.

关键词： 庐枞盆地   马口铁矿床   流体包裹体   岩浆热液  

摘要： 安徽省枞阳县马口铁矿床位于长江中下游成矿带庐枞矿集区内,是区域与正长岩有关的铁铜铀矿床的典型代表。本文在详细野外地质特征观察的基础上,针对马口铁矿床开展了流体包裹体研究工作,明确从主成矿期磁铁矿化阶段至石英硫化物阶段,成矿流体由高温(350~400℃)向中温(220~280℃)演化,但流体的密度(0.8~1.2g/cm^3)及盐度(18~20%)并未发生明显的改变,指示初始流体为高温热液,后期可能无其他来源流体混合。结合前人工作,推断马口铁矿床的形成与黄梅尖岩体分异的岩浆热液活动有关,基底三叠纪膏盐层及原始沉积的铁矿层可能提供了成矿物质。

关键词： 流体包裹体   矽卡岩型   铜、金矿床   狮子山矿田   铜陵  

摘要： 铜陵狮子山矿田矽卡岩型铜、金矿床的流体包裹体可分为气液两相包裹体、含子晶多相包裹体、单相包裹体和含液相CO2的气液包裹体4种类型。其均一温度变化在150~576℃,盐度为4%~56.6%。伴随一致的均一温度,各成矿阶段均存在低盐度与高盐度包裹体群簇共生,说明各成矿阶段曾经发生过沸腾现象。流体包裹体气相成分以H2O和CO2为主,富含CH4;液相成分以Cl^-和Na^+占绝对优势,高F^-含量。从矽卡岩阶段→石英-硫化物阶段→碳酸盐阶段,流体包裹体的均一温度、盐度和δ^18O值逐渐降低,而δD值却变化相反。以上表明,成矿流体是与燕山期岩浆活动有关的NaCl-H2OCO2体系,由封闭向开放体系转变过程中减压造成流体的不混溶。降温、减压和沸腾作用可能是导致流体中巨量铜、金元素沉淀的主要因素。

关键词： 黏性流体   孔隙介质   慢纵波   慢横波   反透射系数  

摘要： 地下岩石由岩石骨架和孔隙流体组成,通常流体含黏性.地震波在地下介质中传播时受岩石骨架和黏性流体的影响会呈现出复杂的变化.本文将流、固体位移和应力连续作为边界条件,推导出含黏性流体孔隙介质分界面上反透射系数方程;通过建立上层为饱油、下层为饱盐水的砂岩孔隙介质模型,开展反透射系数特征研究,分别分析不同频率、不同黏滞系数条件下,含黏性流体孔隙介质分界面上反透射系数随入射角的变化.研究表明,孔隙介质分界面上和等效介质分界面上的反透射系数分别随入射角的变化趋势基本一致,说明方程推导和数值计算的正确性;快纵波反透射系数受频率、流体黏性的影响较小,而快横波反透射系数在一定入射角范围内受频率、流体黏性的影响比较大;由于黏性孔隙流体的作用,慢纵波和慢横波的反透射系数受入射角、频率及流体黏性的影响都很大.

关键词： 有机硅表面活性剂   化学   水性体系   润湿性   表面张力   三硅氧烷   扩散能力   非极性  

摘要： 近期,毕克化学推出了多款有机硅新品。BYK-3450和BYK-3451为水性有机硅表面活性剂,可降低水性体系表面张力,提高水性体系在非极性基材上的润湿性。BYK-3450和BYK-3451是毕克化学新开发的基于三硅氧烷的助剂,它们甚至能在最难润湿的基材上进行很好地润湿,同时也有很好的扩散能力。对比常规的有机硅表面活性剂,它们稳泡性更低,因此能改善施工和应用性能。