A new visualisation and measurement technology for water continuous multiphase flows

This paper reports the performance of a research prototype of a new multiphase flow instrument to non-invasively measure the phase flow rates, with the capability to rapidly image the flow distributions of two- and three-phase (gas and/or oil in water) flows. The research prototype is based on the novel concepts of combining vector Electrical Impedance Tomography (EIT) sensor (for measuring dispersed-phase velocity and fraction) with an electromagnetic flow metre (EMF, for measuring continuous-phase velocity with the EIT input) and a gradiomanometer flow-mixture density metre (FDM), in addition to on-line water conductivity, temperature and absolute pressure measurements. EIT–EMF–FDM data fusion embedded in the research prototype, including online calibration/compensation of conductivity change due to the change of fluids' temperature or ionic concentration, enables the determination of mean concentration, mean velocity and hence the mean flow rate of each individual phase based on the measurement of dispersed-phase distributions and velocity profiles. Results from first flow-loop experiments conducted at Schlumberger Gould Research (SGR) will be described. The performance of the research prototype in flow-rate measurements are evaluated by comparison with the flow-loop references. The results indicate that optimum performance of the research prototype for three-phase flows is confined within the measuring envelope 45–100% Water-in-Liquid Ratio (WLR) and 0–45% Gas Volume Fraction (GVF). Within the scope of this joint research project funded by the UK Engineering & Physical Sciences Research Council (EPSRC), only vertical flows with a conductive continuous liquid phase will be addressed.     

Microstructure and phase composition of cordierite-based co-clinker

The aim of this work is to study the effect of phase composition and microstructure of cordierite-based co-clinkers on the electrical properties and coefficient of thermal expansion of cordierite briquettes. To achieve this aim talc and kaolinite samples were collected from quarries in the Egyptian desert. The samples are characterized using XRD, XRF, polarized light, cathodoluminescence and SEM microscopy attached with EDAX, in addition to X-ray micro-computed tomography (3D- µXCT). The electrical properties and coefficient of thermal expansion of the cordierite briquettes are determined using HiTESTER instrument and automatic Netzsch DIL402 PC dilatometer, respectively.Five talc-based batches were shaped and fired in the temperature range 1000–1350 °C for 2 h. The microstructural and physical characteristics of the resulted cordierite-based co-clinkers depend mainly on the viscosity of the liquid phase developed during firing. The microchemistry of the cordierite briquettes confirms their enrichment of both cordierite and ferroan-cordierite crystallized directly from locally developed melts. The dielectric constant and loss factor values for cordierite briquettes allow their possible use as insulator components in electronic applications.     

Effect of fatigue loading-confining stress unloading rate on marble mechanical behaviors: An insight into fracture evolution analyses

Rocks in underground works usually experience rather complex stress disturbance. For this, their fracture mechanism is significantly different from rocks subjected to conventional triaxial compression conditions. The effects of stress disturbances on rock geomechanical behaviors under fatigue loading conditions and triaxial unloading conditions have been reported in previous studies. However, little is known about the dependence of the unloading rate on fatigue loading and confining stress unloading (FL-CSU) conditions that influence rock failure. In this paper, we aimed at investigating the fracture behaviors of marble under FL-CSU conditions using the post-test X-ray computed tomography (CT) scanning technique and the GCTS RTR 2000 rock mechanics system. Results show that damage accumulation at the fatigue stage can influence the final fracture behaviors of marble. The stored elastic energy for rock samples under FL-CSU tests is relatively larger compared to those under conventional triaxial tests, and the dissipated energy used to drive damage evolution and crack propagation is larger for FL-CSU tests. In FL-CSU tests, as the unloading rate increases, the dissipated energy grows and elastic energy reduces. CT scanning after the test reveals the impacts of the unloading rate on the crack pattern and a fracture degree index is therein defined in this context to represent the crack dimension. It shows that the crack pattern after FL-CSU tests depends on the unloading rate, and the fracture degree is in agreement with the analysis of both the energy dissipation and the amount of energy released. The effect of unloading rate on fracture evolution characteristics of marble is revealed by a series of FL-CSU tests.     

基于小波变换的分数阶微分算法在肝脏肿瘤CT图像纹理增强中的应用

图像纹理增强过程中容易丢失平滑区域纹理细节，而分数阶微分增强虽然能够非线性保留平滑区域纹理细节，但对频率分辨率敏感。针对这个问题，提出一种基于小波变换的分数阶微分纹理增强算法，应用于平扫计算机断层扫描（CT）图像的肝脏肿瘤区域的纹理增强。首先，通过小波变换将图像感兴趣区分解成多个子带分量；其次，基于分数阶微分定义构造一个带补偿参数的分数阶微分掩膜；最后，使用该掩膜与每个高频子带分量进行卷积并利用小波逆变换重组图像感兴趣区。实验结果表明，该方法在使用较大分数阶次显著增强肿瘤区域的高频轮廓信息的同时，有效地保留了低频平滑的纹理细节：增强后的肝细胞癌区域与原区域相比，信息熵平均增加36.56%，平均梯度平均增加321.56%，平均绝对差值平均为9.287；增强后的肝血管瘤区域与原区域相比，信息熵平均增加48.77%，平均梯度平均增加511.26%，平均绝对差值平均为14.097。     

Improved curvature-based registration methods for high-precision dimensional metrology

Multiple measurements using various data acquisition systems are generally required to substancially enhance measurement accuracy, reliability and holisticity of freeform shapes. The obtained multiple measurement data of the shape are transformed and fused into a common coordinate system within a registration technique involving coarse and fine alignments. Standardized methods have been established for fine registration such as Iterative Closest Points (ICP) and its variants. For coarse registration, no conventional method has been adopted yet despite a significant number of techniques which have been developed in the literature to supply an automatic rough matching between data sets.The work presented in this paper proposes an improvement of registration techniques by the consideration of new discrete curvature parameters. Two main issues are addressed in this paper: the coarse registration and the fine registration. For coarse registration, two novel automated methods based on the exploitation of discrete curvatures are presented: an enhanced Hough Transformation (HT) and an improved Ransac Transformation. The use of curvature features in both methods aims to reduce computational cost. For fine registration, a new variant of ICP method is proposed in order to reduce registration error using curvature parameters. A specific distance considering the curvature similarity is combined with Euclidean distance to define the distance criterion used for correspondences searching. Additionally, the objective function is improved by combining the point-to-point (P-P) minimization and the point-to-plane (P-Pl) minimization with automatic weights. The algorithms are applied on simulated and real data performed by a computed tomography (CT) system. The obtained results reveal the benefit of the proposed improved curvature-based registration methods.     

Improved 3D image segmentation for X-ray tomographic analysis of packed particle beds

Although High Resolution X-ray Micro Tomography (HRXMT) has been developed in the past years for the 3D analysis of multiphase mineral particles in packed particle beds, image analysis of fine and/or high-density/high atomic number particles has been limited by existing segmentation algorithms. In this regard, a feature-based segmentation algorithm has been developed and demonstrated to provide a more accurate image processing method for the analysis of such multiphase particle populations. Based on this improved segmentation algorithm, image analyses of packed particle bed samples were compared to segmentation by traditional 3D watershed segmentation. Also, calculation of particle number using optical microscopy, together with a digital camera, was accomplished to validate feature-based segmentation. Detailed procedures and results for sample preparation, image analysis and validation are presented and discussed.     

Influence of 2D rGO nanosheets on the properties of OPC paste

In this experimental study, the effects of 2D reduced graphene oxide (rGO) sheets on the properties of Portland cement paste in comparison to popularly reviewed nanomaterials like aluminium oxide nanopowder (n-Al₂O₃) and colloidal silicon dioxide nanoparticles (n-SiO₂) were investigated. The addition of 0.02% rGO sheets by weight of cement increased the 7 and 28 days flexural strength up to 70% and 23% respectively when compared to control paste. Moreover, its incorporation substantially decreased the sizes of pores/voids in the paste, even compared to the other nanomaterials, as characterized by Mercury Intrusion Porosimetry (MIP) and 3D X-ray Computed Tomography (CT) aided with image analysis technique. The assessment of Portlandite content by Thermo-gravimetric Analysis did not indicate major differences between the pastes, with the exception of the paste incorporating nano-silica. Microstructural analysis by Fourier Transform Infrared Spectroscopy, X-ray diffraction and Scanning Electron Microscopy did not reveal any major differences between the control paste and the pastes incorporating nanomaterials. The overall results suggest that the performance of rGO was better in comparison to other two nanomaterials, despite the significantly lower amounts that were used in the paste.     

Analysis of crude palm oil composition in a chemical process conveyor using Electrical Capacitance Tomography

In this work, we aim to analyse the capability of using a 16-segmented Electrical Capacitance Tomography (ECT) sensor system to monitor the internal composition of a chemical process conveyor that carries crude palm oil (CPO) multiphase flow. The source used to excite the electrodes is a differential potential, instead of the conventional single potential source, in order to obtain an improved sensitivity of the sensor, especially in the central area of the pipe. This system aims to recognise the phase concentration of the flow. The attained concentration profile that is received from the capacitance measurements is capable of providing an image of the liquid and liquid mixture in the pipeline, making the separation process (between oil and liquid waste) much easier and the CPO's quality can be dependably monitored. Experimental results and analysis are presented, and the new excitation technique is shown to provide better sensor sensitivity in the central pipe area. The visualisation results deliver information regarding the flow regime and concentration distribution in a two-phase flow-rate measurement system incorporating a liquid flow-measuring device. The information obtained will assist the design of process equipment, and the verification of existing computational modelling and simulation techniques.