January 2021最新文献_第4页

Forecasting the impacts of severe weather 预报恶劣天气的影响

January 2021 Pub Date : 2021-01-01 DOI: 10.47389/36.1.76

S. Schroeter, H. Richter, C. Arthur, David Wilke, M. Dunford, M. Wehner, E. Ebert

引用次数: 5

Effect of Niobium and Titanium Addition on Formation of Second Phase Particles in CHQ Steel Using Transmission Electron Microscope 添加铌和钛对CHQ钢第二相颗粒形成的影响

January 2021 Pub Date : 2021-01-01 DOI: 10.22581/MUET1982.2101.03

S. Abro

{"title":"Effect of Niobium and Titanium Addition on Formation of Second Phase Particles in CHQ Steel Using Transmission Electron Microscope","authors":"S. Abro","doi":"10.22581/MUET1982.2101.03","DOIUrl":"https://doi.org/10.22581/MUET1982.2101.03","url":null,"abstract":"It is common practice that formation of second phase particles such as nitrides or carbides in the steel matrix has significant role to control the grain size of steel. An attempt is made in the present research work to find out the role of nitrogen to form the nitride particles either with Al, Ti, B, Cr or Si. Two steel samples Steel-A and Steel-B with same titanium and aluminum weight percent in the chemical composition were obtained in hot rolled conditions from international market with only the difference of presence of Niobium in Steel-A. Solution heat treatment was performed at 1350°C with 60 minutes holding time in protherm heat treatment furnace available locally was used to dissolve the particles and then steel samples were reheat treated at 800°C with holding time of 60 minutes and water quenched and microstructure was revealed. Transmission electron microscope connected with Ehlers-Danlos Syndrome (EDS) was used to reveal the morphology of second phase particles. Both samples for a high resolution power Transmission Electron Microscopy (TEM) (Jeol JEM 3010) analysis were prepared by using carbon extraction replica method in 5% Nital solution as an etching technique. Both samples were then caught in copper grid of 3mm for using TEM analysis. TEM micrographs clearly revealed the second phase particles in the matrix of steel. The EDS peaks were studied and it was found that the peaks showed the titanium peaks in both the samples A and B and surprisingly there was no any peak found for aluminum. Stoichiometric calculations were carried out and it was found that weight percent nitrogen required for forming TiN is 0.0073, however the total nitrogen present in both the steels A and B is 0.0058 and 0.0061 respectively. That means that all the nitrogen present in the steel matrix was consumed by titanium to form the Titanium Nitride (TiN) so there was no nitrogen remain to fulfil the requirement of aluminum to form the Aluminum Nitride (AlN) particles.","PeriodicalId":436878,"journal":{"name":"January 2021","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130398792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A Hybrid H∞ Control Based ILC Design Approach for Trajectory Tracking of a Twin Rotor Aerodynamic System 基于混合H∞控制的双转子气动系统轨迹跟踪ILC设计方法

January 2021 Pub Date : 2021-01-01 DOI: 10.22581/MUET1982.2101.16

F. Saleem, Ahsan Ali, I. Shaikh, Muhammad Wasim

{"title":"A Hybrid H∞ Control Based ILC Design Approach for Trajectory Tracking of a Twin Rotor Aerodynamic System","authors":"F. Saleem, Ahsan Ali, I. Shaikh, Muhammad Wasim","doi":"10.22581/MUET1982.2101.16","DOIUrl":"https://doi.org/10.22581/MUET1982.2101.16","url":null,"abstract":"This paper investigates the trajectory tracking problem for a Multi-Input Multi-Output (MIMO) Twin Rotor Aerodynamic System (TRAS) using a hybrid architecture based on an H∞∞∞∞ controller and Iterative Learning Control (ILC). TRAS is a fast, nonlinear coupled system and therefore it is a challenging task to design a control system that ensures the tracking for fast changing trajectories. The controllers proposed in the literature for the TRAS through linear approaches tend to have a large control effort, while the ones designed using the nonlinear approaches track only for smooth input trajectories. Both issues are important from control point of view. In this paper, these issues are addressed by designing a feedback H∞∞∞∞ control that stabilizes the system and a feedforward ILC which reduces the control effort. The H∞∞∞∞ controller achieves the tracking for input trajectories with sharp edges, but the control effort required for tracking is large. With the proposed hybrid approach, tracking is achieved by the H∞∞∞∞ controller whereas the required control effort is reduced in each subsequent iteration by ILC. After a few iterations, accurate tracking at a minimized control effort is achieved. The simulations have been performed using MATLAB software and the controller designed through the proposed approach has been validated on nonlinear model of the system. The results of the proposed technique, compared with the flatness-based and back-stepping control strategies, show that the proposed controller ensures accurate tracking at the reduced control effort.","PeriodicalId":436878,"journal":{"name":"January 2021","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132818583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Petrography and Geochemical Characteristics of Nari Sandstone in Lower Indus Basin, Sindh, Pakistan 巴基斯坦信德省下印度河盆地Nari砂岩岩石学及地球化学特征

January 2021 Pub Date : 2021-01-01 DOI: 10.22581/MUET1982.2101.08

Abdul Majeed Shar

{"title":"Petrography and Geochemical Characteristics of Nari Sandstone in Lower Indus Basin, Sindh, Pakistan","authors":"Abdul Majeed Shar","doi":"10.22581/MUET1982.2101.08","DOIUrl":"https://doi.org/10.22581/MUET1982.2101.08","url":null,"abstract":"Pakistan has been suffering from severe energy crisis for decades. Discovering new oil and gas fields plays significant role in alleviating the energy deficit. Exploitation and development of new fields for the country is very challenging due to economic, technological, social and environmental concerns. Hence, it is essential to assess the potential of hydrocarbon bearing formations using integrated analysis techniques in order to explore the resources efficiently. In this paper, we have analyzed Nari sandstone reservoir potential of the country. The key objectives of the study are to characterize petrographic, mineralogical and microstructural data through laboratory study on Oligocene strata of Nari sandstone in the lower Indus Basin. For this purpose, we collected several exposed outcrop samples from different stations in the onshore areas of Nari Sandstone formation. The work performed includes, the integrated study of petrography using Scanning Electron Microscopy (SEM) along with Energy Dispersive Spectrometry (EDS) application. In addition, Quantitative X-Ray Diffraction (QXRD) analysis was performed. The results revealed that these sandstones were mainly composed of quartz grains, which are surrounded by calcite cement. EDS elemental sequence shows Calcium (Ca), Carbon (C),Silicon (Si), Iron (Fe), Magnesium (Mg), Aluminum (AI) and K (Potassium) in variable intensities in the samples indicating the presence of different minerals within these rocks such as quartz, calcite, clay and ferruginous cement. This study is the comprehensive collection of data of Nari sandstones that is essential to assess the potential of hydrocarbon bearing formations.","PeriodicalId":436878,"journal":{"name":"January 2021","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121975540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Comparison between Dedicated and Flexible Manufacturing Systems: Optimization and Sensitivity Analysis 专用制造系统与柔性制造系统的比较:优化与灵敏度分析

January 2021 Pub Date : 2021-01-01 DOI: 10.22581/MUET1982.2101.12

Abdul Salam Khan, Khawer Naeem, R. Khan

{"title":"A Comparison between Dedicated and Flexible Manufacturing Systems: Optimization and Sensitivity Analysis","authors":"Abdul Salam Khan, Khawer Naeem, R. Khan","doi":"10.22581/MUET1982.2101.12","DOIUrl":"https://doi.org/10.22581/MUET1982.2101.12","url":null,"abstract":"An abrupt change requires a robust and flexible response from a manufacturing system. Dedicated Manufacturing System (DMS) has been a long practiced taxonomy for mass production and minimum varieties. In contrast, Flexible Manufacturing System (FMS) has been introduced for responding to quantity as well as variety issues. This study considers both production taxonomics by using a multi objective model of cost and time. An Integer Linear Programming (ILP) formulation is presented and subsequently validated. The analysis procedure is administered in two phases. In the first phase, comparison of production cost and process time in DMS and FMS is presented. The model is implemented by using an exact solution approach and results show that FMS is a viable option, compared to DMS, according to the criteria of cost, time, and productivity. In the second phase, sensitivity analysis is performed by using several FMS (n) and the impact of cells selection on the performance of system is studied. It is concluded that n=1 (single cell-based FMS) is more relevant for cost minimization; however, n = 6 is a suitable candidate for producing more quantity in given time horizon (process time minimization). Lastly, key findings are reported, and future research avenues are provided.","PeriodicalId":436878,"journal":{"name":"January 2021","volume":"695 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116966393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Transincisional Ultrasound-Guided Quadratus Lumborum Block in Open Renal Surgeries 超声引导下腰方肌阻滞在开放性肾脏手术中的应用

January 2021 Pub Date : 2020-12-31 DOI: 10.36076/ppj.2021.24.e127-e128

引用次数: 0

Changing Scenario of Manufacturing IndustriesDue to Covid 19 新冠肺炎疫情下制造业的变化场景

January 2021 Pub Date : 2020-11-24 DOI: 10.46501/ijmtst061026

Ruchira Srivastava

引用次数: 0