Prediction of Pressure Gradient in Two and Three-phase Flows in Horizontal Pipes Using an Artificial Neural Network Model

Concurrent flow of gas with a mixture of oil and water in production equipment is common necessitating the need for additional investigations to gain more insight and development of more accurate correlations for prediction of flow characteristics including pressure drop. In this study, an experimental study was conducted using air-water and air-water-oil mixtures in a 0.075-m diameter pipe. Superficial gas and liquid velocities ranged from 0.03 to 0.13 m/s and 1.26 to 41.58 m/s respectively. Slug flow was the main flow pattern observed. In addition, transition to annular and annular flow were also observed. Due to the homogeneous nature of the oil-water-air mixture, the three-phase flow was evaluated as a pseudo-two-phase mixture. An Artificial Neural Network (ANN) model developed for the prediction of two- and three- phase pressure drop performed better than all models considered during the evaluation. Generally, it is found that the accuracies for pressure drop were considered adequate

Upward interfacial friction factor in gas and high-viscosity liquid flows in vertical pipes

In this study, experiments were carried out in a vertical 60-mm internal diameter pipe with air and oil (viscosities 100–330 mPa s) constituting the gas and liquid phases. Superficial air and oil velocity ranges used were 9.81–59.06 m/s and 0.024–0.165 m/s, respectively. Visual observations and change in slope of pressure drop–Vsg plot were used to identify flow pattern transition to annular flow. Using the experimental data as well as other reported data, a new correlation to predict interfacial friction factor in upward gas–viscous liquid annular flow regime was developed. Compared to the performance of 16 existing correlations using higher viscosity liquids, that of the new correlation was better. The performance of another correlation we derived for predictions at both low and higher low viscous showed good agreement with measurements. In addition, a neural network model to predict the interfacial friction factor involving both low and high viscous liquids was developed and it excellently described the experimental data

Experimental study of horizontal two- and three-phase flow characteristics at low to medium liquid loading conditions

Anexperimental study is conducted using a 0.075-m ID pipe to investigate characteristics of two-and three-phase stratified flow in a horizontal pipeline. Experiments are conducted under low to medium liquid loading conditions which is common in wet-gas andlongtransportation pipelines. The flow characteristics investigated include flow pattern, liquid holdup and pressure drop. The experimental range covers superficial gas Reynolds numbers from 6314 to 200,734, superficial liquid Reynolds numbers from 160 to4391andwater-cut values from 0 to90%.Differential pressure transducers, quick closing valves and a high-speed camera are utilized to obtain the relevant data and the trends investigated. The observed flow patterns are stratified smooth, stratified wavyandstratified-annular flow. The transitions between flow patterns vary as a function of water-cut. The effect of water-cut on liquid holdup and pressure drop were relatively negligible especially at low water-cut conditions and the fine mixing of the oilwater mixture may bepartially responsible for this. As a result, with the exception offlow pattern transitions, the performances of classical two-phase flow models (for the prediction of liquid holdup and pressure drop) appear unaffected when applied to airoil–water 3-phase flows especially at high water-cuts

Characterization of a Weak Allele of Zebrafish cloche Mutant

Hematopoiesis is a complicated and dynamic process about which the molecular mechanisms remain poorly understood. Danio rerio (zebrafish) is an excellent vertebrate system for studying hematopoiesis and developmental mechanisms. In the previous study, we isolated and identified a cloche172 (clo172) mutant, a novel allele compared to the original cloche (clo) mutant, through using complementation test and initial mapping. Here, according to whole mount in-situ hybridization, we report that the endothelial cells in clo172 mutant embryos, although initially developed, failed to form the functional vascular system eventually. In addition, further characterization indicates that the clo172 mutant exhibited weaker defects instead of completely lost in primitive erythroid cells and definitive hematopoietic cells compared with the clos5 mutant. In contrast, primitive myeloid cells were totally lost in clo172 mutant. Furthermore, these reappeared definitive myeloid cells were demonstrated to initiate from the remaining hematopoietic stem cells (HSCs) in clo172 mutant, confirmed by the dramatic decrease of lyc in clo172runx1w84x double mutant. Collectively, the clo172 mutant is a weak allele compared to the clos5 mutant, therefore providing a model for studying the early development of hematopoietic and vascular system, as well as an opportunity to further understand the function of the cloche gene

Abnormal hubs in global network as potential neuroimaging marker in generalized anxiety disorder at rest

BackgroundMounting studies have reported altered neuroimaging features in generalized anxiety disorder (GAD). However, little is known about changes in degree centrality (DC) as an effective diagnostic method for GAD. Therefore, we aimed to explore the abnormality of DCs and whether these features can be used in the diagnosis of GAD.MethodsForty-one GAD patients and 45 healthy controls participated in the study. Imaging data were analyzed using DC and receiver operating characteristic (ROC) methods.ResultsCompared with the control group, increased DC values in bilateral cerebellum and left middle temporal gyrus (MTG), and decreased DC values in the left medial frontal orbital gyrus (MFOG), fusiform gyrus (FG), and bilateral posterior cingulate cortex (PCC). The ROC results showed that the DC value of the left MTG could serve as a potential neuroimaging marker with high sensitivity and specificity for distinguishing patients from healthy controls.ConclusionOur findings demonstrate that abnormal DCs in the left MTG can be observed in GAD, highlighting the importance of GAD pathophysiology

A two-fluid model for high-viscosity upward annular flow in vertical pipes

Proper selection and application of interfacial friction factor correlations has a significant impact on prediction of key flow characteristics in gas–liquid two-phase flows. In this study, experimental investigation of gas–liquid flow in a vertical pipeline with internal diameter of 0.060 m is presented. Air and oil (with viscosities ranging from 100–200 mPa s) were used as gas and liquid phases, respectively. Superficial velocities of air ranging from 22.37 to 59.06 m/s and oil ranging from 0.05 to 0.16 m/s were used as a test matrix during the experimental campaign. The influence of estimates obtained from nine interfacial friction factor models on the accuracy of predicting pressure gradient, film thickness and gas void fraction was investigated by utilising a two-fluid model. Results obtained indicate that at liquid viscosity of 100 mPa s, the interfacial friction factor correlation proposed by Belt et al. (2009) performed best for pressure gradient prediction while the Moeck (1970) correlation provided the best prediction of pressure gradient at the liquid viscosity of 200 mPa s. In general, these results indicate that the two-fluid model can accurately predict the flow characteristics for liquid viscosities used in this study when appropriate interfacial friction factor correlations are implemented

Mutation in utp15 Disrupts Vascular Patterning in a p53-Dependent Manner in Zebrafish Embryos

Angiogenesis is the process by which the highly branched and functional vasculature arises from the major vessels, providing developing tissues with nutrients, oxygen, and removing metabolic waste. During embryogenesis, vascular patterning is dependent on a tightly regulated balance between pro- and anti-angiogenic signals, and failure of angiogenesis leads to embryonic lethality. Using the zebrafish as a model organism, we sought to identify genes that influence normal vascular patterning.In a forward genetic screen, we identified mutant LA1908, which manifests massive apoptosis during early embryogenesis, abnormal expression of several markers of arterial-venous specification, delayed angiogenic sprouting of the intersegmental vessels (ISV), and malformation of the caudal vein plexus (CVP), indicating a critical role for LA1908 in cell survival and angiogenesis. Genetic mapping and sequencing identified a G to A transition in the splice site preceding exon 11 of utp15 in LA1908 mutant embryos. Overexpression of wild type utp15 mRNA suppresses all observed mutant phenotypes, demonstrating a causative relationship between utp15 and LA1908. Furthermore, we found that injecting morpholino oligonucleotides inhibiting p53 translation prevents cell death and rescues the vascular abnormalities, indicating that p53 is downstream of Utp15 deficiency in mediating the LA1908 phenotypes.Taken together, our data demonstrate an early embryonic effect of Utp15 deficiency on cell survival and the normal patterning of the vasculature and highlight an anti-angiogenic role of p53 in developing embryos

Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop

A Handshake Based Ordered Scheduling MAC Protocol for Underwater Acoustic Local Area Networks

Underwater acoustic local area networks (UA-LANs) can be used to improve the coverage of an underwater network by introducing a tier of local area communications. Media access control (MAC) is a crucial issue for UA-LANs. Existing MAC protocols for terrestrial WLANs cannot be directly applied to UA-LANs due to the acoustic channel features of limited bandwidth and high and variable propagation delay. In this paper, we propose a handshake based ordered scheduling MAC (HOSM) protocol for UA-LANs. The nodes with data packets to be transmitted first reserve the channel in a channel reservation phase. Then an order list is calculated, and the data packets of these nodes are transmitted according to this order list. We develop a control packets transmission adjustment mechanism to reduce collisions of control packets. The key idea of this mechanism is to utilize the information of propagation delay to adjust the time instant of control packets transmitting. To improve channel utilization, we present a variant Max-Min Ant System algorithm to calculate an optimal order for each data transmission round. Simulation results have confirmed that the proposed protocol can achieve high throughput with low delay and good spatial fairness

Interaction Mechanism between Molybdenite and Kaolinite in Gypsum Solution Using Kerosene as the Flotation Collector

This paper aims to understand the fundamental interaction mechanism between molybdenite and kaolinite in gypsum solution using kerosene as collector. Micro-flotation tests were conducted to study the effect of gypsum solution on the flotation performance of mixed −74 μm molybdenite and −10 μm kaolinite mineral. The results showed that the recovery of molybdenite decreased from 86% to 74% while the gypsum solution concentration increased from 0 to 800 mg/L, indicating the detrimental effect of kaolinite on molybdenite flotation could be enhanced by gypsum solution. This is mainly caused by the slime coating of kaolinite on molybdenite through dissolved calcium ion of gypsum solution. In order to confirm the slime coating phenomenon, zeta potential distribution, scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were used to investigate interaction characteristics and mechanisms. The zeta potential distribution results revealed that mixed samples had the value between signal molybdenite and kaolinite samples in gypsum solution, which proved the coating phenomenon of kaolinite on molybdenite. Moreover, the coating phenomenon was becoming more and more obvious with the gypsum solution concentration. The coating phenomenon of kaolinite on molybdenite surface was also directly observed from SEM results. The AFM results provided further evidence for the possibility of slime coating, as the adhesion force increased with the gypsum solution concentration, which means the aggregates of molybdenite and kaolinite were becoming more stable