检索结果-内蒙古大学图书馆

Rupture of a surfactant-laden draining thin film

Physical Review Fluids 2024年第7期9卷 074004-074004页

作者： Atul S. Vivek Ranabir Dey Harish N. Dixit Control Actuation Systems Group Vikram Sarabhai Space Center Indian Space Research Organisation Thiruvananthapuram 695022 India Department of Mechanical and Aerospace Engineering Indian Institute of Technology Hyderabad Kandi Sangareddy Telangana 502285 India Centre for Interdisciplinary Programs Indian Institute of Technology Hyderabad Kandi Sangareddy Telangana 502285 India

Surfactant-laden thin liquid films overlaid on solid substrates are encountered in a variety of industrial and biological settings. As these films reach submicron thickness, they tend to become unstable owing to the influence of long-range dispersion forces. In the current study, we investigate how gravitational drainage affects the stability attributes of such thin liquid films. Using scaling arguments, we demonstrate that gravity and dispersion forces can exert their influence simultaneously over a wide range of film thicknesses. In the lubrication limit, we carry out linear stability analysis and nonlinear simulations to understand the evolution of draining thin films. Linear stability indicates the existence of two unstable modes and two cutoff wave numbers, as opposed to a single unstable mode and a unique cutoff wave number observed in stationary films. It is also found that surfactant-laden flowing films are more stable than stationary films with surfactants as well as draining films with clean interfaces. The origin of stabilization is identified as the enhanced surfactant perturbations generated due to drainage. We demonstrate that films exhibiting intermediate levels of surfactant activity and significant drainage exhibit the lowest rates of disturbance growth, leading to extending the time of rupture.

关键词： Instability of free-surface flows Lubrication theory Thin fluid films Van der Waals interaction

来源：评论

学校读者我要写书评

暂无评论

MOMENT STABILITY OF STOCHASTIC PROCESSES WITH APPLICATIONS TO control systems

arXiv

引用

arXiv 2022年

作者： Ganguly, Arnab Chatterjee, Debasish Department of Mathematics Louisiana State University United States Indian Institute of Technology Bombay Systems & Control Engineering India

We establish new conditions for obtaining uniform bounds on the moments of discrete-time stochastic processes. Our results require a weak negative drift criterion along with a state-dependent restriction on the sizes of the one-step jumps of the processes. The state-dependent feature of the results make them suitable for a large class of multiplicative-noise processes. Under the additional assumption of Markovian property, new result on ergodicity has also been proved. There are several applications to iterative systems, control systems, and other dynamical systems with state-dependent multiplicative noise, and we include illustrative examples to demonstrate applicability of our *** Codes 60J05, 60J20, 60F17, 93D05, 93E15 Copyright © 2022, The Authors. All rights reserved.

关键词： Markov processes

来源：评论

学校读者我要写书评

暂无评论

Semi-Bandit Learning for Monotone Stochastic Optimization*

Semi-Bandit Learning for Monotone Stochastic Optimization*

引用

Annual IEEE Symposium on Foundations of Computer Science

作者： Arpit Agarwal Rohan Ghuge Viswanath Nagarajan Computer Science & Engineering Indian Institute of Technology Bombay Mumbai India H. Milton Stewart School of Industrial and Systems Engineering Georgia Institute of Technology Atlanta USA Industrial and Operations Engineering University of Michigan Ann Arbor USA

ISBN: (数字)9798331516741

ISBN: (纸本)9798331516758

Stochastic optimization is a widely used approach for optimization under uncertainty, where uncertain input parameters are modeled by random variables. Exact or approximation algorithms have been obtained for several fundamental problems in this area. However, a significant limitation of this approach is that it requires full knowledge of the underlying probability distributions. Can we still get good (approximation) algorithms if these distributions are unknown, and the algorithm needs to learn them through repeated interactions? In this paper, we resolve this question for a large class of “monotone” stochastic problems, by providing a generic online learning algorithm with $\sqrt{T\log T}$ regret relative to the best approximation algorithm (under known distributions). Importantly, our online algorithm works in a semi-bandit setting, where in each period, the algorithm only observes samples from the random variables that were actually probed. Our frame-work applies to several fundamental problems in stochastic optimization such as prophet inequality, Pandora's box, stochastic knapsack, stochastic matchings and stochastic submodular optimization.

关键词： Computer science Uncertainty Stochastic processes Approximation algorithms Probability distribution Random variables Optimization

来源：评论

学校读者我要写书评

暂无评论

Optimal Questionnaires for Screening of Strategic Agents

Optimal Questionnaires for Screening of Strategic Agents

引用

IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Anuj S. Vora Ankur A. Kulkarni Systems and Control Engineering Indian Institute of Technology Bombay Mumbai

During the COVID-19 pandemic the health authorities at airports and train stations try to screen and identify the travellers possibly exposed to the virus. However, many individuals avoid getting tested and hence may misreport their travel history. This is a challenge for the health authorities who wish to ascertain the truly susceptible cases in spite of this strategic misreporting. We investigate the problem of questioning travellers to classify them for further testing when the travellers are strategic or are unwilling to reveal their travel histories. We show there are fundamental limits to how many travel histories the health authorities can recover.

关键词： COVID-19 Pandemics Conferences Games Signal processing Airports History

来源：评论

学校读者我要写书评

暂无评论

Effect of decarburization-induced abnormal grain growth on the formation of cracks in ASTM A335 grade P11 low alloy steel seamless pipes

引用

engineering Failure Analysis 2025年 178卷

作者： Sahu, Dhanendra Kumar Suryawanshi, Nilesh Bajpeyee, Dhananjay Prasad, M.J.N.V. Microstructural Engineering and Mechanical Performance Laboratory Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Bombay Mumbai400 076 India Quality Control Division Jindal Saw Limited Sukeli Nagothane Raigad402 126 India

The present study investigated the cause of the frequent failures of the hot-pierced and stretch-rolled low alloy ASTM A335 Grade P11 low alloy steel pipes consisting of ferrite and pearlite microstructure. A detailed microstructural examination that includes optical microscopy and scanning electron microscopy in conjunction with electron back-scattered diffraction (EBSD) and energy dispersive spectroscopy (EDS) was performed across the thickness of the failed and sound pipe samples. Microhardness measurements were performed to evaluate the microstructural inhomogeneity, if any across the thickness of the failed and sound pipe samples. It has been noticed that the substantial fraction of abnormally grown ferrite grains in thick decarburized layers, being softer in nature, could not resist the applied pressures and thereby resulted in easy cracking under tensile loading condition thus leading to the failure of the steel pipes during subsequent hydro-pressure testing or in application. © 2025 Elsevier Ltd

关键词： Decarburization

来源：评论

学校读者我要写书评

暂无评论

Recurrent Sliding Mode-Based State Observer Design for a Subset of Nonlinear systems

Recurrent Sliding Mode-Based State Observer Design for a Sub...

引用

International Conference on control, Automation, Robotics and Vision (ICARCV)

作者： Gael P. Atheupe Bhagyashri T. Gurjar Bruno Monsuez Renault Group and IP Paris Guyancourt FRANCE Department of Aerospace Engineering Intelligent Systems & Control Lab Indian Institute of Technology Bombay Mumbai India Computer science & systems engineering Lab (U2IS) of ENSTA Paris Institute Poly-technique de Paris (IP Paris) Palaiseau FRANCE

ISBN: (数字)9798331518493

ISBN: (纸本)9798331518509

This paper introduces a novel Sliding Mode-Based Observer tailored for a specific subset of nonlinear systems of order $\boldsymbol n$ featuring Lipschitz nonlinearities. The study establishes stability conditions that ensure convergence of the estimation error (s) in finite time until order $\boldsymbol n$ , thus, providing an accurate state (s) estimation without the necessity for disturbance matching conditions. Furthermore, the study presents an extension of the scope of application of the proposed method to tackle a unique scenario characterized by a time-varying and non-invertible function of the output dynamics of the system model. The effectiveness of the proposed observer is showcased through simulation examples.

关键词： Estimation error Automation Accuracy Observers Stability analysis Nonlinear dynamical systems Time-varying systems Robots Convergence

来源：评论

学校读者我要写书评

暂无评论

Formation control of differential-drive robots with input saturation and constraint on formation size

TechRxiv

引用

TechRxiv 2023年

作者： Agrawal, Ayush Bharatheesha, Mukunda Kolathaya, Shishir The Department of Mechanical Engineering The Indian Institute of Technology Bombay India Robert Bosch Centre for Cyber Physical Systems India ARTPARK Indian Institute of Science Bengaluru India Indian Institute of Science Bengaluru India

This technical note is supplementary material to the original work in [1], which has been accepted for presentation at the 62nd IEEE Conference on Decision and control (CDC) 2023. Sections and subsections of this technical note have been cited in the footnotes of [1]. Some of the proofs omitted from [1] are discussed in those sections and subsections. In addition to this, the reasoning for some arguments or expressions in [1], along with few alternative proposals are talked through in this note. Note: Some equations in this technical note are taken directly from [1]. The labels of these equations in the two documents may not match. Equation of [1] are cited at appropriate positions to keep the lucidity of these technical note intact. © 2023, CC BY-NC-SA.

关键词： Lyapunov methods

来源：评论

学校读者我要写书评

暂无评论

Agnostic Learning of Mixed Linear Regressions with EM and AM Algorithms

arXiv

引用

arXiv 2024年

作者： Ghosh, Avishek Mazumdar, Arya Systems and Control Engg. Centre for Machine Intelligence for Data Sciences Indian Institute of Technology Bombay India Halıcıoglu Data Science Institute University of California San Diego United States

Mixed linear regression is a well-studied problem in parametric statistics and machine learning. Given a set of samples, tuples of covariates and labels, the task of mixed linear regression is to find a small list of linear relationships that best fit the samples. Usually it is assumed that the label is generated stochastically by randomly selecting one of two or more linear functions, applying this chosen function to the covariates, and potentially introducing noise to the result. In that situation, the objective is to estimate the ground-truth linear functions up to some parameter error. The popular expectation maximization (EM) and alternating minimization (AM) algorithms have been previously analyzed for this. In this paper, we consider the more general problem of agnostic learning of mixed linear regression from samples, without such generative models. In particular, we show that the AM and EM algorithms, under standard conditions of separability and good initialization, lead to agnostic learning in mixed linear regression by converging to the population loss minimizers, for suitably defined loss functions. In some sense, this shows the strength of AM and EM algorithms that converges to "optimal solutions" even in the absence of realizable generative models. Copyright © 2024, The Authors. All rights reserved.

关键词： Linear regression

来源：评论

学校读者我要写书评

暂无评论

Network-Agnostic Voltage-to-Power Sensitivities of a Real-Time Reduced Active Distribution Network

Network-Agnostic Voltage-to-Power Sensitivities of a Real-Ti...

引用

IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia)

作者： Manorath Prasad Zakir Hussain Rather Reza Razzaghi Suryanarayana Doolla Department of Energy Science and Engineering Indian Institute of Technology Bombay Mumbai India Department of Electrical and Computer Systems Engineering Monash University Melbourne Australia

The advent of distribution-level phasor measurement units (D-PMUs) has enhanced the observability of active distribution networks (ADNs) and improved their energy management and control. Recently, various ADN control strategies that require detailed network parameter information have been proposed based on the voltage-to-power sensitivities of the ADN nodes. This paper proposes a new realistic approach to determining nodal voltage-to-power sensitivities of a synchrophasor measurement-based reduced ADN model. The real-time synchrophasor data dynamically updates the parameters of the reduced equivalent model to follow the time-varying operating conditions of the ADN accurately. The voltage-to-power sensitivities of the retained observable nodes are derived from the power flow Jacobian matrix using reduced equivalent model parameters. Thus, the proposed approach is agnostic about detailed line impedance data of the complex ADN. Further, the computational complexity is significantly decreased with the reduced number of nodes in the equivalent ADN model. The proposed approach has been tested on modified IEEE-33 bus benchmark system with high penetration of photovoltaic inverters using a DIgSILENT PowerFactory MATLAB co-simulation platform.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Additive manufacturing of tungsten,tungsten-based alloys,and tungsten matrix composites

引用

Tungsten 2023年第1期5卷 1-31页

作者： Shuai-Hang Pan Gong-Cheng Yao Yi-Nan Cui Fan-Shi Meng Chuan Luo Tian-Qi Zheng Gurminder Singh Department of Mechanical Engineering University of UtahSalt Lake CityUT 84112USA University of California-Los Angeles Los AngelesCA 90095USA Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China University of Grenoble Alpes CNRSGrenoble INPSIMaP38000 GrenobleFrance Department of Civil and Systems Engineering Johns Hopkins University3400 N.Charles StreetBaltimoreMD 21218USA Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China School of Mechanical and Materials Engineering University College DublinDublin 4Ireland Department of Mechanical Engineering Indian Institute of Technology BombayMumbai 400076India

Tungsten(W) materials are gaining more and more attention due to the extended applications of metallic systems in the extreme *** W’s unique characteristics like room-temperature brittleness,additive manufacturing(AM)techniques could give them a higher design flexibility and *** the growing focus and thriving development of W-faced AM techniques,since the mechanical performance of additively manufactured W parts is still unsatisfactory,a critical review to further explore the possibilities of combining W and AM processes is urgently *** this review,we systematically explain the fundamentals of AM processes for W *** the traditional classification,we further discuss the widely used AM processes including wire arc additive manufacturing(WAAM),electron beam melting(EBM),laser powder bed fusion(LPBF),laser direct energy deposition(laser DED),and other modified yet emergent AM ***,since additively manufacturing W materials is processing parameter-sensitive,we illustrated the effects of various important processing parameters on the AM process control and final parts’ *** this detailed understanding,various categories of AM-compatible W materials(i.e.,pure W,W alloys,and W composites) were presented,and their general mechanical performance,distinct role(particularly the role of different alloying elements and added secondary-phase particles in W),and application-oriented benefits have been *** clarifying the current status,main challenges,and triumphant successes for additively manufacturing W materials,we further provide a concise prospect into the development of additively manufactured(AMed) W materials by integrating potential fabrication,measurement,alloy design,and application’s *** summary,this critical review investigates the fundamental and practical problems crucially limiting the applications of AMed W materials,and the comprehensive discussion concentr

关键词： Tungsten Additive manufacturing Alloy design Composite design Cracking Mechanical properties

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：