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Stochastic Models to Mitigate Sparse Sensor Attacks in Continuous-Time Non-Linear Cyber-Physical Systems

Computers, Materials & Continua 2023年第9期76卷 3189-3218页

作者： Borja Bordel Sánchez Ramón Alcarria Tomás Robles Information Technologies department Universidad Politécnica de MadridMadrid28031Spain Geospatial Information department Universidad Politécnica de MadridMadrid28031Spain

Cyber-Physical Systems are very vulnerable to sparse sensor attacks.But current protection mechanisms employ linear and deterministic models which cannot detect attacks precisely.Therefore,in this paper,we propose a new non-linear generalized model to describe Cyber-Physical Systems.This model includes unknown multivariable discrete and continuous-time functions and different multiplicative noises to represent the evolution of physical processes and randomeffects in the physical and computationalworlds.Besides,the digitalization stage in hardware devices is represented too.Attackers and most critical sparse sensor attacks are described through a stochastic process.The reconstruction and protectionmechanisms are based on aweighted stochasticmodel.Error probability in data samples is estimated through different indicators commonly employed in non-linear dynamics(such as the Fourier transform,first-return maps,or the probability density function).A decision algorithm calculates the final reconstructed value considering the previous error probability.An experimental validation based on simulation tools and real deployments is also carried out.Both,the new technology performance and scalability are studied.Results prove that the proposed solution protects Cyber-Physical Systems against up to 92%of attacks and perturbations,with a computational delay below 2.5 s.The proposed model shows a linear complexity,as recursive or iterative structures are not employed,just algebraic and probabilistic functions.In conclusion,the new model and reconstructionmechanism can protect successfully Cyber-Physical Systems against sparse sensor attacks,even in dense or pervasive deployments and scenarios.

关键词： Cyber-physical systems sparse sensor attack non-linear models stochastic models security

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Revisiting the analytical solutions for ultimate bearing capacity of pile embedded in rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1506-1519页

作者： A.Picardo M.A.Millán R.Galindo A.Alencar Escuela Técnica Superior de Arquitectura Universidad Politécnica de MadridMadrid28040Spain Escuela Técnica Superior de Ingenieros de Caminos Canales y Puertos de MadridUniversidad Politécnica de MadridMadrid28040Spain

This paper investigates the validity and shortcomings of the existing analytical solution for the ultimate bearing capacity of a pile embedded in a rock mass using the modified HoekeBrown failure criterion.Although this criterion is considered a reference value for empirical and numerical calculations,some limitations of its basic simplifications have not been clarified yet.This research compares the analytical results obtained from the novel discontinuity layout optimization(DLO)method and the numerical solutions from the finite difference method(FDM).The limitations of the analytical solution are considered by comparing different DLO failure modes,thus allowing for the first time a critical evaluation of its scope and conditioning for implementation.Errors of up to 40%in the bearing capacity and unrealistic failure modes are the main issues in the analytical solution.The main aspects of the DLO method are also analyzed with an emphasis on the linearization of the rock failure criterion and the accuracy resulting from the discretization size.The analysis demonstrates DLO as a very efficient and accurate tool to address the pile tip bearing capacity,presenting considerable advantages over other methods.

关键词： Discontinuity layout optimization(DLO) Analytical solution Bearing capacity deep foundations HoekeBrown failure criterion Finite difference method(FDM)

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Influence of parameters on the microstructure of a duplex stainless steel joint welded by a GMAW welding process

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Progress in Natural Science:Materials International 2022年第4期32卷 415-423页

作者： Sandra Chacón-Fernández Antonio Portolés García Gerardo Romaní Labanda Universidad Politécnica de Madrid Escuela Técnica Superior de Ingenieros Industriales UPM

Duplex stainless steels(DSSs) are widely used in industry for their desirable properties. Any fusion welding technique modifies the microstructure and, consequently, the properties of the material. This paper presents a parametric study of the variables that determine the energy contribution(current, voltage and welding speed) and the structural modifications produced during gas metal arc welding. The analysis comprises metallographic study,phase balance, dimensioning of the weld beads and tensile and hardness tests. The influence of the variables studied on the thermal cycles obtained(temperatures reached and cooling rate) was determined by using a finite element model. The results showed that, in addition to the indicated parameters, the parameter power transfer per volume(W/m3) and the geometry in the bead must be controlled due to their influence on the heat flow distribution and phase balance.

关键词： Welding Heat input GMAW Duplex stainless steels (DSS) Finite element model (FEM)

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An execution control method for the Aerostack aerial robotics framework

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Frontiers of Information Technology & Electronic Engineering 2019年第1期20卷 60-75页

作者： Martin MOLINA Alberto CAMPORREDONDO Hriday BAVLE AlejANDro RODRIGUEZ-RAMOS Pascual CAMPOY department of Artificial Intelligence Universidad Politécnica de Madrid Centre for Automation and Robotics Universidad Politécnica de Madrid

Execution control is a critical task of robot architectures which has a deep impact on the quality of the final system. In this study, we describe a general method for execution control, which is a part of the Aerostack software framework for aerial robotics, and present technical challenges for execution control and design decisions to develop the method. The proposed method has an original design combining a distributed approach for execution control of behaviors(such as situation checking and performance monitoring) and centralizes coordination to ensure consistency of the concurrent execution. We conduct experiments to evaluate the method. The experimental results show that the method is general and usable with acceptable development efforts to efficiently work on different types of aerial missions. The method is supported by standards based on a robot operating system(ROS) contributing to its general use, and an open-source project is integrated in the Aerostack framework. Therefore, its technical details are fully accessible to developers and freely available to be used in the development of new aerial robotic systems.

关键词： Aerial robotics Control architecture Behavior-based control Executive system

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基于计算缩放的光滑粒子水动力学方法模拟飞机油箱剧烈晃动问题

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Acta Mechanica Sinica 2023年第2期39卷 39-48页

作者： Calderon-Sanchez Javier Martinez-Carrascal Jon Gonzalez Leo Miguel CEHINAV Model Basin ETSI NavalesUniversidad Politécnica de MadridMadrid28040Spain

大型民用飞机的机翼设计用于承受从大气阵风到湍流到着陆冲击的各种载荷,机翼是需要进一步研究的重要结构.改进机翼设计的主要方法之一是分析晃动对承载液体的柔性机翼状结构动力学的阻尼效应.这将通过开发实验装置来实现,该装置将有助... 详细信息

大型民用飞机的机翼设计用于承受从大气阵风到湍流到着陆冲击的各种载荷,机翼是需要进一步研究的重要结构.改进机翼设计的主要方法之一是分析晃动对承载液体的柔性机翼状结构动力学的阻尼效应.这将通过开发实验装置来实现,该装置将有助于建立和再现涉及物理领域的数值模型.因此,本工作的目的是使用数值方法光滑粒子流体动力学(SPH)作为主要数值工具,分析晃动在降低飞机结构设计载荷方面的影响.本研究中的一个关键因素是对比例实验的需求,这是评估计算工具是否能够准确近似不同比例的注册测量值的必要步骤.为此,建立了一个垂直振动水槽的数值模型,该模型是一个完全耦合的流固耦合问题.该结构通过质量-弹簧-阻尼器系统建模,对于内部流体,使用δ-SPH方法.特别是,研究了两个开放性问题:第一个问题是,当储罐的初始加速度是标准重力值的十倍时,重力对阻尼和能量耗散现象的影响程度;第二种问题旨在确认,当根据量纲分析对问题参数进行缩放时,SPH方程正确地再现了缩放定律.

关键词： SPH Sloshing Gravity Computational scaling

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Rock mass structural recognition from drill monitoring technology in underground mining using discontinuity index and machine learning techniques

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International Journal of Mining Science and Technology 2023年第5期33卷 555-571页

作者： Alberto Fernández JoséA.Sanchidrián Pablo Segarra Santiago Gómez Enming Li Rafael Navarro Universidad Politécnica de Madrid–ETSI Minas y Energía Spain universidad de Salamanca–GIR Charrock Spain

A procedure to recognize individual discontinuities in rock mass from measurement while drilling(MWD)technology is developed,using the binary pattern of structural rock characteristics obtained from in-hole images for calibration.Data from two underground operations with different drilling technology and different rock mass characteristics are considered,which generalizes the application of the methodology to different sites and ensures the full operational integration of MWD data analysis.Two approaches are followed for site-specific structural model building:a discontinuity index(DI)built from variations in MWD parameters,and a machine learning(ML)classifier as function of the drilling parameters and their variability.The prediction ability of the models is quantitatively assessed as the rate of recognition of discontinuities observed in borehole logs.Differences between the parameters involved in the models for each site,and differences in their weights,highlight the site-dependence of the resulting models.The ML approach offers better performance than the classical DI,with recognition rates in the range 89%to 96%.However,the simpler DI still yields fairly accurate results,with recognition rates 70%to 90%.These results validate the adaptive MWD-based methodology as an engineering solution to predict rock structural condition in underground mining operations.

关键词： Drill monitoring technology Rock mass characterization Underground mining Similarity metrics of binary vectors Structural rock factor Machine learning

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旋转输运速度场积分SPH对流扩散方程解的收敛性

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Acta Mechanica Sinica 2023年第2期39卷 61-70页

作者： Pablo Eleazar Merino-Alonso Fabricio Macià Antonio Souto-Iglesias departamento de Arquitectura Constructión y Sistemas Oceánicos y NovalesUniversidad Politécnica de MadridMadridSpain departamento de Matemática e Informática Aplicadas a las Ingenierías Civil y Naval Universidad Politécnica de MadridMadridSpain

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件... 详细信息

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件,即我们称之为正条件,则收敛是有保证的.这个条件是核的傅里叶变换其径向轮廓的一阶矩为正,并通过数值验证说明了分析结果.根据L2范数和最大范数,比较了使用不同核包括SPH社区更常用的核(即Wendland核以及三次和线性样条核)获得的数值解.除此之外,提出并测试了一个病理核,该核不满足正条件,导致了非收敛结果.这一事实表明,在对流扩散方程的情况下,正条件不仅是收敛的充分条件,也是必要条件.

关键词： Smoothed particle hydrodynamics Numerical analysis Diffusion Convergence Fourier analysis

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Experimental study on lightweight expanded clay at particle level:Breakage of isolated grains

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1846-1858页

作者： Elías Roces-Alonso Jose Estaire Miriam Martín-Ruiz Jesús González-Galindo ETS de Ingenieros de Caminos Universidad Politécnica de MadridSpain Laboratorio de Geotecnia CEDEXMadridSpain

In this study,more than 1500 particles of lightweight expanded clay aggregate(LECA)are individually loaded up to breakage,following different patterns of contact(from 2 to 7)using a purpose-built apparatus.Consequently,a statistical model for predicting the number of fragments into which a grain breaks as a function of the number of contacts and their diameter is proposed.The number of fragments is found to follow a statistical binomial-type distribution function that depends on the number of contacts.In addition,a model based on Bayesian networks,capable of assessing the number of fragments and their size(measured as normalized weight)as a function of the number of contacts,is implemented.The proposed method is applicable when performing discrete element method(deM)simulations on granular media in which grain breakage plays a relevant role.

关键词： Lightweight expanded clay aggregate(LECA) Grain fragmentation Grain breakage Biaxial grain load

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Architecture as device:Estrangement theory from literature to architecture

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Frontiers of Architectural Research 2022年第1期11卷 1-12页

作者： Qirui Wan Sergio Martín Blas department of Architectural design ETSAMUniversidad Politécnica de MadridMadrid28040Spain

What is the estrangement of architecture?The concept has been incessantly mentioned by academics while there seems to be a lack of discussion systematically sorting out the significance,influence,and origins of estrangement asanarchitectural concept.Thiswork aims to discern the meaning of estrangement from the beginning and its process of entering the field of architecture.The first part is expected to answer the following questions:what is estrangement’s original meaning in the field of literature and its variantions?The second part determines what estrangement is in architecture and in what form estrangement is represented according to these arguments.The third part points out the difference during this translation fromliterature to architecture and demonstrates the reasonable inference thatmay actually compose the possibleway of applying the estranging technique in architecture.

关键词： Estrangement Architectural strategy Literature concept decontextualization Anthropopathic architecture

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Building health monitoring in the old town of madrid:applicability of SAR Imagery to the monitoring of underground works through classification indexes

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International Journal of Digital Earth 2021年第3期14卷 271-287页

作者： Adrian Jesus Garcia Beatriz González-Rodrigo Sara Martinez Ruben Martinez Miguel Marchamalo Topography and Geomatics Lab ETSI CaminosCanales y PuertosUniversidad Politécnica de MadridMadridSpain ETS de Ingeniería Civil Universidad Politécnica de MadridMadridSpain

The old city centers of many major cities represent a great challenge from a constructive point of view since the foundations of the buildings consist of an aggregation of previous constructions.This endorses thorough monitoring activities during any underground construction.The capabilities of the persistent scatterer interferometry(PSI)can be exploited to cope with these monitoring needs.However,the old city centers represent a very challenging urban scenario since the rooftops are usually filled with air conditioning systems and due to the fact that the streets are usually crowded.This work assesses the applicability of the PSI technique under this challenging scenario.Moreover,it proposes a set of novel classification indexes that allow an objective assessment of the building’s health and the impact derived from any activity.They can be applied in deformation monitoring and risk evaluation in urban areas.The applicability of the technique and the proposed indexes is validated in the monitoring of underground construction works in the old city center of madrid comparing the results against on-ground measurements and identifying the potential and the limitation of the technique.

关键词： Satellite-based monitoring historical city center building health monitoring persistent scatterer interferometry urban planning

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