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Interaction between local corrosion and flow field of natural gas long-distance pipeline by artificial rectangular defect pit

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Journal of Iron and Steel Research(International) 2022年第6期29卷 1026-1038页

作者： Zhuo-wei Tan Zhen-bo Wang Shu-yu Bai Da-lei Zhang Sheng-zhu Zhang Frank Cheng Shao-hua Xing You-hai Jin China University of Petroleum(East China) Qingdao 266580ShandongChina Xiangtan University Xiangtan 411105HunanChina School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina China Academy of Safety Science and Technology Beijing 100012China University of Calgary CalgaryAB T2N 1N4Canada State Key for Marine Corrosion and Protection Luoyang Ship Material Research InstituteQingdao 266237ShandongChina

The corrosive environment in long-distance natural gas pipeline was simulated by the online high shear stress flow test platform.The interaction between flow fields and local corrosion in different local corrosion stages was studied by machining different depths rectangular defect pit(RDP)on X80 pipe steel specimens.The electrochemical signals of each specimen under high shear stress flow were measured online using an integrated three-electrode and electrochemical system.Raman spectroscopy confirmed that the corrosion scale of X80 pipeline steel in CO_(2)-saturated National Association of Corrosion Engineers solution was composed of FeCO_(3).The scanning electron microscope images displayed variations in microstructure of the corrosion scale at different RDP depths and different areas.The flow field fluctuations induced by RDP were analyzed by computational fluid dynamics simulations and the development of local corrosion pits was discussed in terms of integrity of corrosion scale,convective mass transfer,and diffusion mass transfer.

关键词： CO_(2) corrosion Flow condition Rectangular defect pit Local corrosion Corrosion electrochemistry

A study of fire propagation in coal seam with numerical simulation of heat transfer and chemical reaction rate in mining field

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International Journal of Mining Science and Technology 2019年第6期29卷 873-879页

作者： Moisés Oswaldo Bustamante Rúa Alan José Daza Aragón Pablo Bustamante Baena National University of Colombia Cr 65 # 63 20 CIMEX Minerals Institute

Spontaneous combustion of coal is a problem that affects the mining operation and generates environ-mental,economic,social and geotechnical impacts.This phenomenon has been divided into two pro-cesses:ignition and propagation.Fire propagation develops in coal seams because of a set of factors such as direction and wind speed,fracturing and temperature.In this work,heat transfer and chemical kinetics are studied from conservation equations of energy and species,respectively,using the software COMSOL Multiphysics to simulate the propagation of fires in coal seams.Two possible scenarios were analyzed that usually occur in the walls of the coal seams,such as fire focus and fire complete screens.It was found that the propagation kinetics of the fire changes depending on the temperature,the fractur-ing of rock mass and the area of fire influence.For temperature values lower than 300℃,there is con-sumption around 250 cm^3/h,values around 700℃,the consumption is 1500 cm^3/h,and for fires of 1200℃ have values of 3000 cm^3/h.Depending on the speed of propagation can vary from 4 to 17cm/day,considering on the level and fracturing of the final wall of the open pit.

关键词： Spontaneous combustion of coal Open pit mines Simulation Heat transfer Chemical reaction COMSOL

On the cell biology of pit cells,the liver-specific NK cells

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World Journal of Gastroenterology 2000年第1期6卷 1-11页

作者： Luo DZ Vermijlen D Ahishali B Triantis V Plakoutsi G Braet F Vanderkerken K Wisse E Laboratory for Cell Biology and Histology Free University of Brussels(VUB)Brussels-JetteBelgium Department of Pathology Guangxi Medical University NanningChina Laboratory for Cell Biology and Histology Free University of Brussels(VUB)Brussels-JetteBelgium Department of Hematology and Immunology Free University of Brussels(VUB)Brussels-JetteBelgium

INTRODUCTION Natural killer (NK) cells are functionally defined by their ability to kill certain tumor cells and virus-infected cells without prior

关键词： Subject headings pit cells hepatic natural killer cells large granular lymphocytes

A comparison of strategic mine planning approaches for in-pit crushing and conveying, and truck/shovel systems

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International Journal of Mining Science and Technology 2018年第2期28卷 205-214页

作者： M.Nehring P.F.Knights M.S.Kizil E.Hay School of Mechanical and Mining Engineering The University of Queensland

In a global environment where energy and labor are becoming increasingly expensive, continuous mining systems such as In-pit Crushing and Conveying(IPCC) systems have been advanced as offering a real alternative to conventional truck haulage systems. The implementation of IPCC systems in hard rock operations in open pit mines however requires different and more comprehensive planning approaches in order to adequately reflect the practical aspects associated with these. This paper investigates the impact that these approaches may have on the implementation of IPCC systems on a basic metalliferous deposit amenable to open pit exploitation. A strategic life of mine plan to provide numerous economic indicators for each approach is analyzed and compared to traditional truck haulage systems. The mine planning and evaluation process highlights the increased overall resource recovery that may accompany the use of IPCC systems. This investigation also provides insights into the issues associated with IPCC and the scale and type of operation and orebody that is likely to provide a feasible alternative to truck haulage.

关键词： In pit crusher conveyor systems Strategic mine planning Resource recovery Surface metalliferous mining Mine optimization Truck and shovel

Statistical analysis to establish an ignition scenario based on extrinsic and intrinsic variables of coal seams that affect spontaneous combustion

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International Journal of Mining Science and Technology 2019年第5期29卷 731-737页

作者： M.O.Bustamante Rúa A.J.Daza Aragón P.Bustamante Baena J.D.Osorio Botero school mines national university of colombiamedellín 050036colombia

Spontaneous combustion of coal seams in open pit mines is a problem that occurs in coal mines around the world.Theories have been developed that express several factors which generate self-heating in the coal and favor combustion.The synergy of these factors contributes to the increase in the temperature of oxidation reactions,facilitating the culmination of the activation energy of the system,in which the ignition develops and the reaction is spontaneous.Currently,the incidence of each variable’s susceptibility to coal combustion is unknown,so in this work a methodology was developed to determine statistically which of the variables has the greatest contribution in the phenomenon.Descriptive statistics,atypical values detection,principal component determination,cluster analysis,and logistic regression were used to determine how many indicator variables are necessary to describe susceptibility to coal combustion.For the analysis,21,000 data from different seams of two open-pit coal mines in endwalls and abandoned pits were processed with consideration given to extrinsic and intrinsic factors.Seam temperature,atmospheric pressure,wind speed,oxygen,methane,height,ash,volatile matter,heat power,vitrinite,liptinite and the Hardgrove Index are the most influential variables in the phenomenon.

关键词： Coal fire Self-ignition Statistics analysis Open pit mines Spontaneous combustion

Overburden management in open pits: options and limits in large limestone quarries

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International Journal of Mining Science and Technology 2019年第2期29卷 217-228页

作者： Claudio Oggeri Taddeo Maria Fenoglio Alberto Godio Raffaele Vinai Department of Environment Land and Infrastructure Engineering Politecnico di Torino College of Engineering Mathematics and Physical Sciences University of Exeter

The management of overburden is an important task in open pit exploitations. Site topography and morphology as well as geological and geotechnical properties of natural and remoulded materials are the most important factors affecting the disposal phase. Economic and environmental requirements must be followed in order to achieve the best reclamation results, keeping into account site constraints such as slope stability, hauling and dumping issues, and interactions with groundwater. This paper deals with the above mentioned issues, illustrating a rational approach applied on the case of a large limestone quarry where the thickness of the overburden is relevant and the spoil material has to be dumped in a flooded pit. The proposed multidisciplinary approach led to the selection of most suitable methods for excavation, transportation and disposal. The selection was based on a detailed laboratory and site characterisation that defined favorable and adverse factors to be considered during the preliminary study of a large quarrying project.

关键词： Open pit Overburden Soil testing Limestone quarry Muck On-site testing

3D analysis for pit evolution and pit-to-crack transition during corrosion fatigue

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第4期14卷 292-299页

作者： Xiao-guang HUANG Jin-quan XU Department of Engineering Mechanics China University of Petroleum Department of Engineering Mechanics Shanghai Jiao Tong University

This paper presents a deterministic model to predict the pit evolving morphology and crack initiation life of corrosion fatigue.Based on the semi-ellipsoidal pit assumption,the thermodynamic potential including elastic energy,surface energy and electrochemical energy of the cyclically stressed solid with an evolving pit is established,from which specific parameters that control the pit evolution are introduced and their influence on the pit evolution are evaluated.The critical pit size for crack nucleation is obtained from stress intensity factor criterion and the crack nucleation life is evaluated by Faraday's law.Meanwhile,this paper presents a numerical example to verify the proposed model and investigate the influence of cyclic load on the corrosion fatigue crack nucleation life.The corrosion pit appears approximately as a hemisphere in its early formation,and it gradually transits from semicircle to ellipsoid.The strain energy accelerates the morphology evolution of the pit,while the surface energy decelerates it.The higher the stress amplitude is,the smaller the critical pit size is and the shorter the crack initiation life is.

关键词： pit Evolving morphology Thermodynamic potential Critical pit size Crack nucleation

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基于pit的皮肤镜图像分类方法研究

光电子．激光 2022年第5期33卷 505-512页

作者：韦春苗徐岩蒋新辉魏一铭兰州交通大学电子与信息工程学院柳州铁道职业技术学院人工智能学院

随着计算机技术的进步,现有的Transformer被扩展成处理计算机视觉任务的网络结构。为提高黑色素瘤的早期确诊率以提高皮肤病患者的治愈率,本文提出一种改进的基于pit(pyramid pooling transformer)的网络模型来实现对7种皮肤病变的皮肤... 详细信息

随着计算机技术的进步,现有的Transformer被扩展成处理计算机视觉任务的网络结构。为提高黑色素瘤的早期确诊率以提高皮肤病患者的治愈率,本文提出一种改进的基于pit(pyramid pooling transformer)的网络模型来实现对7种皮肤病变的皮肤镜图像进行自动分类。本文模型主要由pit模块和抗干扰模块等2个部分组成,pit继承了ViT的优点,并通过池化进行空间尺寸转换来提高模型的鲁棒性,经过预训练的pit网络拥有大量的自然图像特征,且pit部分网络可为下游的分类任务提供所需的图像特征,本文设计出抗干扰模块,用来抵抗皮肤镜图像中的干扰因素(如毛发、异物遮挡)的影响,从而提高模型性能、提高分类精度。实验结果表明,本文模型在ISIC 2018验证集上的分类准确率、精确率、召回率、F1-score值分别高达91.58%、83.59%、89.92%、86.34%,每秒传输帧数(frames per second,FPS)达到85 Hz与现有的几种先进的分类网络相比,分类性能和模型效率都有所提高,具有相对优势,证明本文模型具有一定的实用价值。

关键词：图像处理图像分类 pit 抗干扰模块

PRINCIPLES FOR OPTIMUM DESIGN OF OPEN pit MINES

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中国有色金属学会会刊：英文版 1997年第1期7卷 2-5页

作者： Shi, Zhongmin Feng, Zhongren Xu, Changyou Zhang, Youdi Wuhan Univ of Technology Wuhan China

ＰＲＩＮＣＩＰＬＥＳＦＯＲＯＰＴＩＭＵＭＤＥＳＩＧＮＯＦＯＰＥＮＰＩＴＭＩＮＥＳＳｈｉＺｈｏｎｇｍｉｎ，ＦｅｎｇＺｈｏｎｇｒｅｎ，ＸｕＣｈａｎｇｙｏｕＤｅｐａｒｔｍｅｎｔｏｆＭｉｎｅｒａｌＲｅｓｏｕｒｃｅａｎｄＥｎｖ... 详细信息

ＰＲＩＮＣＩＰＬＥＳＦＯＲＯＰＴＩＭＵＭＤＥＳＩＧＮＯＦＯＰＥＮＰＩＴＭＩＮＥＳＳｈｉＺｈｏｎｇｍｉｎ，ＦｅｎｇＺｈｏｎｇｒｅｎ，ＸｕＣｈａｎｇｙｏｕＤｅｐａｒｔｍｅｎｔｏｆＭｉｎｅｒａｌＲｅｓｏｕｒｃｅａｎｄＥｎｖｉｒｏｎｍｅｎｔＥｎｇｉｎｅｅｒｉ...

关键词： open pit limit optimum design numerical method design criterion basic principle