Effect of Meander on Bridge Pier Scour

Lots of work regarding the scour around bridge piers in straight channelhave been done in the past by many researchers. Many factors which affectscour around piers such as shape of piers, size, positioning and orientationetc. have been studied in detail by them. However, similar studies inmeandering channels are scanty. Very few researchers have studied theeffect of angular displacement which has considerable effects of scouraround bridge piers.In this paper an attempt has been made to carry out a detailed study ofangular displacement on scour. A constant diameter bridge pier of circularshape has been tested in a meandering channel bend with bend angle as 800 .The test bed was prepared by using uniform sand having d50 as 0.27 mmand run was taken for a discharge of 2.5 l/s.

Some characteristics of surfaces machined with abrasive waterjet turning

This paper presents an experimental study of abrasive waterjet turning of an extrusion aluminum alloy (AlMg0,7Si). The aim of the paper is to determine differences of two methods from the point of view of machined surface quality and the depth of penetration, i.e., the diameter of the parts after the turning process. During the experiments, the traverse speed of the cutting head and the rotation of the turned parts were changed, other parameters, like pressure of the water, abrasive mass flow rate were kept constant. Diameter and some surface roughness parameters of the test parts were measured after the machining. On the base of experimental results, advantages, and disadvantages of two methods are explained in the paper.

Experimental Study and Prediction Model for Hydrate Plugging Formation in Single-Pass Gas-Dominated Pipes with Diameter Reduction

Summary Gas hydrate plugging in flowlines acts as a major blockage risk in oil, gas, and natural gas hydrate production. Current studies on hydrate plugging is mainly conducted in pipes with a constant diameter, whereas the effects of varying diameters have been less explored. Pipes with diameter reductions are very common in the oil and gas production process. Herein, by performing experiments with pipes of four different sizes, including one with a constant diameter and three with diameter reductions, the hydrate plugging in single-pass gas-dominated pipes with diameter reduction is investigated systematically, the results of which show that the existence of diameter reduction can facilitate the deposition of hydrate particles on pipe walls and the formation of a hydrate deposition layer. Meanwhile, hydrate sloughing occurs during the growth of the hydrate deposition layer under fluid shear force. With the increase in the diameter reduction ratio or subcooling for hydrate formation, the hydrate deposition is observed to increase significantly, thus resulting in the reduction of time for hydrate plugging. According to these results, the hydrate plugging mechanism in pipes with diameter reduction is proposed. Further, in combination with the hydrate deposition difference between the inside and outside of the arc-shaped low-speed area, a new numerical model is established for hydrate plugging prediction in the pipe with diameter reduction, which can predict the growth and evolution of the hydrate deposition layer accurately with the consideration of the diameter’s reduction. The results of this work provide a valuable guidance for the targeted prevention and management of hydrate plugging in flowlines with diameter reductions.

Diameter, width and thickness in the hyperbolic plane

In hyperbolic geometry there are several concepts to measure the breadth or width of a convex set. In the first part of the paper we collect them and compare their properties. Than we introduce a new concept to measure the width and thickness of a convex body. Correspondingly, we define three classes of bodies, bodies of constant with, bodies of constant diameter and bodies having the constant shadow property, respectively. We prove that the property of constant diameter follows to the fulfilment of constant shadow property, and both of them are stronger as the property of constant width. In the last part of this paper, we introduce the thickness of a constant body and prove a variant of Blaschke’s theorem on the larger circle inscribed to a plane-convex body of given thickness and diameter.

Investigation of the influence of narrowing annular channel and Reynolds number on formation of Tayler-Gortler vortexes

Abstract. The article investigates the Taylor-Gortler vortices arising in a swirling flow when the annular channel narrows. Several options for the geometry of the narrowed annular channel are researched. In the first case, the outer cylinder with a constant diameter and the inner cone with a variable cone angle are considered. In the second case, on the contrary an inner cylinder with a constant diameter and an outer cone with a variable cone angle are considered. All geometries were tested at different Reynolds numbers Re. = 8.3-103…21•103. As a result, the analysis of the propagation of secondary vortices along the length of the annular channel is presented.

Case Report: A Case of Infant Bronchial Dieulafoy's Disease and Article Review

Background: Bronchial Dieulafoy's disease (BDD), characterized by constant diameter arterial malformation, is rare, especially among infants. The pathogenesis and clinical features of pediatric patients are unknown. Misdiagnosis and biopsy operations may lead to potential massive hemorrhage, which endangers the patient's life.Case Presentation: Here, we present a case of a 9-month-old boy who was diagnosed with BDD with massive hemoptysis. The boy was cured by embolization of the bronchial artery and was in good health at the 1-year follow-up. In addition, we searched PubMed, Google Scholar, and Web of Science databases using keyword “Bronchial Dieulafoy's Disease (BDD)” and found six additional cases of pediatric BDD.Conclusion: It is still insufficient to draw a conclusion about the origin of the disease. Bronchial angiography and endobronchial ultrasonography are considered promising methods to diagnose Dieulafoy's disease of the bronchus. Bronchoscopy with transbronchial biopsy should not be deployed due to the high risk of fatal hemorrhage. Explicit clinical case reports of BDD are needed to enhance the understanding of this rare disease.

Brain capillary structures of schizophrenia cases and controls show a correlation with their neuron structures

Brain blood vessels constitute a micrometer-scale vascular network responsible for supply of oxygen and nutrition. In this study, we analyzed cerebral tissues of the anterior cingulate cortex and superior temporal gyrus of schizophrenia cases and age/gender-matched controls by using synchrotron radiation microtomography or micro-CT in order to examine the three-dimensional structure of cerebral vessels. Over 1 m of cerebral blood vessels was traced to build Cartesian-coordinate models, which were then used for calculating structural parameters including the diameter and curvature of the vessels. The distribution of vessel outer diameters showed a peak at 7–9 μm, corresponding to the diameter of the capillaries. Mean curvatures of the capillary vessels showed a significant correlation to the mean curvatures of neurites, while the mean capillary diameter was almost constant, independent of the cases. Our previous studies indicated that the neurites of schizophrenia cases are thin and tortuous compared to controls. The curved capillaries with a constant diameter should occupy a nearly constant volume, while neurons suffering from neurite thinning should have reduced volumes, resulting in a volumetric imbalance between the neurons and the vessels. We suggest that the observed structural correlation between neurons and blood vessels is related to neurovascular abnormalities in schizophrenia.

Modelling Negative Correlation in Complex Networks Via Anti-Transitivity

Negative correlation appears often in complex networks. For example, in social networks, negative correlation corresponds to rivalry between agents in the network, while in stock market graphs, negative correlation corresponds stocks that move in opposite directions in price action. We present a simplified, deterministic model of negative correlation in networks based on the principle of anti-transitivity: a non-friend of a non-friend is a friend. In the Iterated Local Anti-Transitivity (ILAT) model, for every node u in a given time-step, we add an anti-clone node that is adjacent to the complement of the closed neighborhood of u. We prove that graphs generated by the ILAT model satisfy several properties observed in complex networks, such as high density and densification power laws, constant diameter, and high local clustering. We also prove that the domination and cop numbers of graphs generated by the ILAT model are bounded above by small, absolute constants as time increases.