检索结果-南通市图书馆

Robust Optimization Method of Cylindrical Roller Bearing by Maximizing Dynamic Capacity Using Evolutionary Algorithms

引用

Journal of Harbin Institute of Technology(New Series) 2022年第5期29卷 20-40页

作者： Kumar Gaurav rajiv tiwari Twinkle Mandawat Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahati 781039India

Optimization of cylindrical roller bearings(CRBs)has been performed using a robust design.It ensures that the changes in the objective function,even in the case of variations in design variables during manufacturing,have a minimum possible value and do not exceed the upper limit of a desired range of percentage variation.Also,it checks the feasibility of design outcome in presence of manufacturing tolerances in design variables.For any rolling element bearing,a long life indicates a satisfactory performance.In the present study,the dynamic load carrying capacity C,which relates to fatigue life,has been optimized using the robust design.In roller bearings,boundary dimensions(i.e.,bearing outer diameter,bore diameter and width)are standard.Hence,the performance is mainly affected by the internal dimensions and not the bearing boundary dimensions mentioned formerly.In spite of this,besides internal dimensions and their tolerances,the tolerances in boundary dimensions have also been taken into consideration for the robust optimization.The problem has been solved with the elitist non-dominating sorting genetic algorithm(NSGA-II).Finally,for the visualization and to ensure manufacturability of CRB using obtained values,radial dimensions drawing of one of the optimized CRB has been made.To check the robustness of obtained design after optimization,a sensitivity analysis has also been carried out to find out how much the variation in the objective function will be in case of variation in optimized value of design variables.Optimized bearings have been found to have improved life as compared with standard ones.

关键词： cylindrical roller bearing optimization robust design elitist non-dominating sorting genetic algorithm(NSGA-II) fatigue life dynamic load carrying capacity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimal Design of Tapered Roller Bearings Based on Multi⁃Physics Objectives Using Evolutionary Algorithms

引用

Journal of Harbin Institute of Technology(New Series) 2023年第1期30卷 73-84页

作者： rajiv tiwari Rahul M.P.Chandran Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahati 781039India

Rolling element bearing is the most common machine element in rotating machinery.An extended life is among the foremost imperative standards in the optimal design of rolling element bearings,which confide on the fatigue failure,wear,and thermal conditions of bearings.To fill the gap,in the current work,all three objectives of a tapered roller bearing have been innovatively considered respectively,which are the dynamic capacity,elasto-hydrodynamic lubrication(EHL)minimum film⁃thickness,and maximum bearing temperature.These objective function formulations are presented,associated design variables are identified,and constraints are discussed.To solve complex non⁃linear constrained optimization formulations,a best⁃practice design procedure was investigated using the Artificial Bee Colony(ABC)algorithms.A sensitivity analysis of several geometric design variables was conducted to observe the difference in all three objectives.An excellent enhancement was found in the bearing designs that have been optimized as compared with bearing standards and previously published works.The present study will definitely add to the present experience based design followed in bearing industries to save time and obtain assessment of bearing performance before manufacturing.To verify the improvement,an experimental investigation is worthwhile conducting.

关键词： dynamic capacity evolutionary algorithm optimum design tapered roller bearings temperature tolerance analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Review:Measurement-Based Monitoring and Fault Identification in Centrifugal Pumps

引用

Journal of Harbin Institute of Technology(New Series) 2023年第2期30卷 25-47页

作者： Janani Shruti Rapur rajiv tiwari Aakash Dewangan D.J.Bordoloi Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahati 781039India

Condition based maintenance(CBM) is one of the solutions to machinery maintenance requirements. Latest approaches to CBM aim at reducing human engagement in the real-time fault detection and decision making. Machine learning techniques like fuzzy-logic-based systems, neural networks, and support vector machines help to reduce human involvement. Most of these techniques provide fault information with 100% confidence. It is undeniably apparent that this area has a vast application scope. To facilitate future exploration, this review is presented describing the centrifugal pump faults, the signals they generate, their CBM based diagnostic schemes, and case studies for blockage and cavitation fault detection in centrifugal pump(CP) by performing the experiment on test rig. The classification accuracy is above 98% for fault detection. This review gives a head-start to new researchers in this field and identifies the un-touched areas pertaining to CP fault diagnosis.

关键词： centrifugal pumps condition-based maintenance fault diagnosis machine learning techniques review

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings:a novel trial misalignment approach

引用

Propulsion and Power Research 2021年第1期10卷 58-82页

作者： Prabhat Kumar rajiv tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries,transport vehicles,and in several other applications.Excessive vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous accidents.So,there is a need for perceiving the dynamic nature and identifying the faults for the safe,smooth and effective operation of machines.This paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor balancing.Active magnetic bearing(AMB)misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment cases.Additional trial misalignments are provided in addition to the unknown misalignments of the residual misalignment case.For the execution of this methodology,the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically developed.The offset discs result in the gyroscopic effect at high rotor speeds.Equations of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions.A fast Fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and forcecurrent stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification algorithm.Identified values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown misalignments.Testing of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness and robustness.The algorithm is found to be exhi

关键词： Misalignment Unbalance Active magnetic bearing Gyroscopic moment Fast Fourier transform Identification

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Detection of asymmetric transmission error in geared rotor system through transverse vibration analysis using full spectrum

引用

Propulsion and Power Research 2020年第3期9卷 255-280页

作者： Bhyri Rajeswara Rao rajiv tiwari General Motors Technical Center India Pvt.Ltd. BangaloreKarnataka560066India Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Transmission error(TE)in geared rotors is a predominant source of inherent excitation at the pitch point of the gear meshing.In this paper,a transverse vibration analysis is presented to study the effect of TE on geared rotors.Due to asymmetry in the TE,it is expected to have both forward and backward whirls excited during rotor whirling,which could be used for its detection.This aspect has been envisioned first time in the present work.To capture this,an approach of orienting the line of action of a gear-pair along oblique plane is considered and the mathematical modeling has been performed of a simple spur gear-pair connecting two parallel shafts at its mid-span with an asymmetric TE.To capture the forward and backward whirls,equations of motion are converted into a complex form that facilitates obtaining response in full spectrum.The response of system model with assumed transmission error and gear-pair parameters has been obtained through a numerical simulation,which shows distinctly the forward and backward whirls due to the TE.Through a simple test rig experimentation,a similar behaviour was observed in transverse vibrations of geared rotors in the full spectrum,which validate the proposed model.

关键词： Geared rotor Asymmetric transmission error Transverse vibration Forward and backward whirls Full spectrum

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Estimation of the internal and external damping from the forward and backward spectrum of a rotor with a fatigue crack

引用

Propulsion and Power Research 2020年第1期9卷 62-74页

作者： Dipendra Kumar Roy rajiv tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India Faculty of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India

Both internal and external damping are concurrently present in a rotor system.However,the internal damping that originates from various sources often leads to instability in the rotor system,and hence its accurate estimation is crucial.The goal of the present paper is to distinctly estimate both external and internal damping in a Jeffcott rotor containing transverse crack.The modelling of the fatigue crack is based on the assumption of a switching crack,which additionally provides the internal damping due to rubbing on crack faces,which is hardly addressed in literature.Moreover,the fatigue crack leads to the forward and backward whirls due to asymmetry in the rotor.In the process of development of the identification procedure in the form of the regression equation for the estimation of internal damping,other important unknown rotor system parameters,like the external damping,unbalance and loss of stiffness of the shaft due to the crack,are also identified.This reduces the estimation error of the internal damping due to reduction in deviations of other model parameters.Numerically simulated responses are obtained from equations of motion of the rotor system in the form of a closed-form expression and by the Runge-Kutta integration method.The full-spectrum response data(both magnitude and phase)are utilized during the testing of the proposed identification procedure.Phase corrections have been incorporated in the full-spectrum.Measurement noise is added in numerical responses during identification of parameters to check the robustness of the algorithm and found to be working satisfactorily.

关键词： Internal damping External damping Switching crack Unbalance Full spectrum

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The IRAK-ERK-p67phox-Nox-2 axis mediates TLR4, 2-induced ROS production for IL-lp transcription and processing in monocytes

引用

Cellular & Molecular Immunology 2016年第6期13卷 747-763页

作者： Ankita Singh Vishal Singh rajiv L. tiwari Tulika Chandra Ashutosh Kumar Madhu Dikshit Manoj K. Barthwal Pharmacology Division CSIR-Central Drug Research Institute B.S. 10/1 Sector 10 Sitapur Road Jankipuram Extension Lucknow 226031 Uttar Pradesh India Department of Transfusion Medicine and Blood Bank King George's Medical University Lucknow Uttar Pradesh India Department of Pathology King George's Medical University Lucknow Uttar Pradesh India

In monocytic cells, Toll-like receptor 4 （TLR4）- and TLR2-induced reactive oxygen species （ROS） cause oxidative stress and inflammatory response; however, the mechanism is not well understood. The present study investigated the role of interleukin-1 receptor-associated kinase （IRAK）, extracellular signal-regulated kinase （ERK）, p67phox and Nox-2 in TLR4- and TLR2-induced ROS generation during interleukin-1 beta （IL-1β） transcription, processing, and secretion. An IRAK1/4 inhibitor, U0126, PD98059, an NADPH oxidase inhibitor （diphenyleneiodonium （DPI））, and a free radical scavenger （N-acetyl cysteine （NAC））-attenuated TLR4 （lipopolysaccharide （LPS））- and TLR2 （Pam3csk4）-induced ROS generation and IL-1β production in THP-1 and primary human monocytes. An IRAK1/4 inhibitor and siRNA-attenuated LPS- and Pam3csk4-induced ERK-IRAK1 association and ERK phosphorylation and activity. LPS and Pam3csk4 also induced IRAK1/4-, ERK- and ROS-dependent activation of activator protein-1 （AP-1）, IL-1β transcription, and IL-1β processing because significant inhibition in AP-1 activity, IL-lp transcription, Pro- and mature IL-p expression, and caspase-1 activity was observed with PD98059, U0126, DPI, NAC, an IRAK1/4 inhibitor, tanshinone Ila, and IRAK1 siRNA treatment. IRAK-dependent ERK-p67phox interaction, p67phox translocation, and p67phox-Nox-2 interaction were observed. Nox-2 siRNA significantly reduced secreted IL-lp, IL-1β transcript, pro- and mature IL-1β expression, and caspase-1 activity indicating a role for Nox-2 in LPS- and Pam3csk4-induced IL-1β production, transcription, and processing. In the present study, we demonstrate that the TLR4- and TLR2-induced IRAK-ERK pathway cross-talks with p67phox-Nox-2 for ROS generation, thus regulating IL-1β transcription and orocessin; in monocvtic cells.

关键词： IL-1β IRAK monocytes ROS TLR

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Correction to: The IRAK-ERK-p67phox-Nox-2 axis mediates TLR4, 2-induced ROS production for IL-1β transcription and processing in monocytes

引用

Cellular & Molecular Immunology 2019年第12期16卷 946-946页

作者： Ankita Singh Vishal Singh rajiv L.tiwari Tulika Chandra Ashutosh Kumar Madhu Dikshit Manoj K.Barthwal Pharmacology Division CSIR-Central Drug Research InstituteB.S.10/1Sector 10Sitapur RoadJankipuram ExtensionLucknow 226031 Uttar PradeshIndia Department of Transfusion Medicine and Blood Bank King George’s Medical UniversityLucknowUttar PradeshIndia Department of Pathology King George’s Medical UniversityLucknowUttar PradeshIndia

In this article,published online on 31 August 2015,there was an unintended error during image processing of Fig.2b leading to pasting of total ERK andβ-Actin blots not intended for this experiment.These blots have now been replaced with the total ERK andβ-Actin panels that were generated for this experiment.The corrected Fig.2b is shown here.However,the conclusion made from the experiment remains unaltered,and this correction has no bearing on the final outcome of the study.The inconvenience caused by this error is deeply regretted.

关键词： correction intended conclusion

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

应用脂质体凝集反应板快速检测活动性结核病患者抗原

引用

国际结核病与肺部疾病杂志 2008年第2期3卷 55-62页

作者： R. P. tiwari S. K.Garg R. N. Bharmal S. Kartikeyan P. S. Bisen 王博（译）吴雪琼（校）何广学（审） Diagnostic Division Nicholas Piramal India Limited Pawane Navi MumbaiJagatpura Jaipur India Institute of Biotechnology and Allied Sciences Seedling Academy of Design Technology and Management Jagatpure Jaipur India Department ofBiochemistry University of Nebraska Lincoln Nebraska USA Department of Microbiology Preventive ＆ Social Medicine Rajiv Gandhi Medical College Kalwa Thane India 不详

背景:共有1360例临床确诊的肺内结核、肺外结核患者标本及其他非结核标本。目的:建立一种快速、敏感、特异的检测不同临床标本中结核分枝杆菌糖脂抗原的方法。研究设计:在1-乙基-3-3-二甲基氨丙基碳化二亚胺氢氯化物和N-羟基丁二酰胺溶... 详细信息

背景:共有1360例临床确诊的肺内结核、肺外结核患者标本及其他非结核标本。目的:建立一种快速、敏感、特异的检测不同临床标本中结核分枝杆菌糖脂抗原的方法。研究设计:在1-乙基-3-3-二甲基氨丙基碳化二亚胺氢氯化物和N-羟基丁二酰胺溶液中将亲和纯化的兔抗糖脂抗体(IgG)结合在脂质体颗粒(0.2～0.4 um)上,制备TB/M检测板的反应试剂。结果:当检测样本中存在糖脂抗原时,连接抗体的脂质体在4 min内会出现1个深蓝色的凝集点。而正常健康人或其他疾病患者的样本未见凝集点。结果显示该方法检测活动性肺结核患者临床样本中的结核分枝杆菌糖脂抗原的敏感性可低至1 ng/ml,临床灵敏度为97.4%,特异性为96.9%。结论:TB/M检测试验比较经济(一次检测只需4个印度卢比或0.09美元)、快速(4 min),似乎有助于结核病流行国家大规模检测结核性脑膜炎、肺结核和其他肺外结核患者多种生物学标本(脑脊液、胸液、关节液、血清和组织活检标本)。

关键词：分枝杆菌,结核结核,脑膜脑脊液脂质体中枢神经结核糖脂抗体

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：