System Identification

Subspace identification and Controller design for Distillation Column

by Saravanakumar Gurusamy

This paper discusses the system identification of
Multi-input Multi-output (MIMO) system and design of Modelmore This paper discusses the system identification of
Multi-input Multi-output (MIMO) system and design of Model
Predictive Controller (MPC) for identified model. Distillation
column process is taken for studies. It is an important processing
unit in petroleum refining and chemical industries, and needs to
be controlled close to the optimum operating conditions because
of economic incentives. Subspace identification method is used to
identify the MIMO model and Model Predictive Controller is
designed for identified model. MPC is widely adopted in the
process industry as an effective means to deal with large
multivariable constrained control problems.

Vector-dependent Functionally Pooled ARX Models for the Identification of Systems Under Multiple Operating Conditions

by Fotis Kopsaftopoulos

Proceedings of the 16th IFAC Symposium on System Identification, (SYSID), Brussels, Belgium, July 2012.

Vector-dependent Functionally Pooled ARX Models for the Identification of Systems Under Multiple Operating Conditions

by Fotis Kopsaftopoulos

Proceedings of the 16th IFAC Symposium on System Identification, (SYSID), Brussels, Belgium, July 2012.

Considerações sobre a Modelagem Estocástica dos Coeficientes do Algoritmo Adaptativo IAF-PNLMS

by Francisco Souza

system identification

by Prashant Kumar Tripathi

System Identification of Wing-Sailed Unmanned Marine Vehicle

by Muhammad Fuady

System Identification term project. with Mirza Salman Baig

This paper deals with system identification of an autonomous wind-propelled unmanned marine vehicle. Functionally,... more This paper deals with system identification of an autonomous wind-propelled unmanned marine vehicle. Functionally, such a vehicle is the marine equivalent of an unmanned aerial vehicle (UAV), and would serve similar purposes such as remote monitoring, unmanned ferrying, environmental monitoring, surveillance, and minefield mapping. In this paper, system identification for an autonomous wind-propelled marine craft is carried out. Using input and output data obtained from experimental trials, system identification results are shown through numerical analysis. ARMAX SISO approach , State Space based Model identifications, and Observer / Kalman Identification methods will be used to build identification of the model. Comparison between these methods also presented here.

Freeze-drying modeling and monitoring using a new neuro-evolutive technique

by Elena-Niculina Dragoi

Authors: Elena-Niculina Drăgoi, Silvia Curteanu, Davide Fissore

This paper is focused on the design of a black-box model for the process of freeze-drying of pharmaceuticals. A new... more This paper is focused on the design of a black-box model for the process of freeze-drying of pharmaceuticals. A new methodology based on a self-adaptive differential evolution scheme is combined with a back-propagation algorithm, as local search method, for the simultaneous structural and parametric optimization of the model represented by a neural network.
The tool is proposed for modeling the freeze-drying process. By this way, it is possible to determine off-line both the temperature and the residual ice content in the product vs. time given the values of the operating conditions (the temperature of the heating shelf and the pressure in the drying chamber). This makes possible to understand if the maximum temperature allowed by the product is trespassed, and when the sublimation drying is complete, thus providing a valuable tool for recipe design and optimization.
Besides, the black box model can be used to monitor the freeze-drying process: in this case, the measurement of product temperature is used as input variable of the neural network in order to provide an in-line estimation of the state of the product (temperature and residual amount of ice).
Various examples are presented and discussed, thus pointing out the strength of the tool.

Interlinked positive and negative feedback loops design emotional sweating.

by Sasa Brankovic

Identification of Petri Nets using timing information

by Gianmaria De Tommasi

published in 3rd International Workshop on Dependable Control of Discrete Systems (DCDS'11), Saarbrücken, Germany, June 2011

This paper deals with the identification problem for deterministic timed Petri net systems. The proposed algorithm... more This paper deals with the identification problem for deterministic timed Petri net systems. The proposed algorithm identifies a timed Petri net starting from the observed timed sequences. The main idea is to use the timing information to accelerate the net identification with respect to the untimed approaches. In particular, exploiting the timing it is possible to determine a set of counterexamples, i.e., a set of strings that do not belong to the language, that can be used to improve the net identification. The identification approach proposed in this paper focuses on free labeled timed Petri nets.

Improving real-time identification of Petri Nets using timing information

by Gianmaria De Tommasi

published in 14th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA'09), Mallorca, Spain, September 2009

This paper deals with the problem of identifying a Petri net system given an observed sequence of events generated by... more This paper deals with the problem of identifying a Petri net system given an observed sequence of events generated by it and an observed sequence of output vectors associated to the marking of the measurable places. The problem is not new in the literature. The original contribution of this work consists in the use of the timing information associated to the net so as to improve its identification. The fact that a transition has not fired for a time larger than its expected delay is here exploited to obtain a list of counterexamples, i.e. the strings that does not belong to the language, even if a whole language is not known. This accelerates the identification procedure. The problem of identifying a ¿-free labeled Petri net system is here considered, that is the identification of a net where a label may be associated to more than one transition, and no transition may by labelled with the empty string.

Efficient reinforcement learning using Gaussian processes

by Marc Deisenroth

State-space inference and learning with Gaussian processes

by Marc Deisenroth

System identification of skin conductance response in depression - An attempt to probe the neurochemistry of limbic system

by Sasa Brankovic

2008

The Unique Identity (UID) Project and the New ‘Bureaucratic Moment’ in India

by Swagato Sarkar

University of Oxford, QEH Working Paper Series – QEHWPS194 - Working Paper Number 194

At various points in its career the Indian state has deployed technologies to govern the country. In its latest move,... more At various points in its career the Indian state has deployed technologies to govern the country. In its latest move, the state has undertaken a number of large scale projects to install digital technology, the most controversial of these is the Unique Identity Project, an ongoing project which is registering the biometric, along with demographic, information of the residents. In this paper, I will try to understand what is politically at stake in this technological intervention. I would like to explore whether these interventions signal a shift in thinking around the institutional, while negotiating the political in a particular way;
whether it reconciles the participatory and procedural impulses of Indian democracy – negotiates with particular claims; and whether it brings a change in the state-citizen relationship. I will argue that these interventions cannot be understood as an orthodox neoliberal policy initiative – rather it articulates a new “will to power” and a desire to segregate, yet preserve the state, and free the executive from the encumbrance of populist democracy. Theoretically, the main thrust of this paper is to understand the “general economy of power”, as Michel Foucault calls it, which is unfolding in India around the issues of capitalist growth, inequality, governance, social protection and technology.

Vulnerability assessment for medieval civic towers

by Sara Casciati

Casciati, S. and Faravelli, L. (2010). “Vulnerability assessment for medieval civic towers”. Structure and Infrastructure Engineering, 6(1&2), 193-203. ISSN:1573-2479.

DATE AND PLACE OF PUBLICATION: February 2010; Taylor & Francis Ltd, Abingdon, OX14 4RN Oxon, England.

ABSTRACT: The seismic vulnerability of an ancient civic bell tower is studied. Rather than seeing it as an... more ABSTRACT: The seismic vulnerability of an ancient civic bell tower is studied. Rather than seeing it as an intermediate stage towards a risk analysis, the assessment of vulnerability is here pursued for optimising the retrofit design. Vulnerability curves are drawn by carrying out a single time history analysis of a model calibrated based on experimental data. From the results of this analysis, the medians of three selected performance parameters are estimated, and they are used to compute, for each of them, the probability of exceeding or attaining the three corresponding levels of light, moderate and severe damage. For future development, the same model can be used to numerically implement the effects of different retrofitting solutions and to re-estimate the associated vulnerability curves. The ultimate goal is to provide a numerical tool able to drive the optimisation process of a retrofit design by the comparison of the vulnerability estimates associated with the different retrofitting solutions.

KEYWORDS: ancient masonry tower; damage assessment; seismic vulnerability; dynamic measurements; modal parameters; time history analysis

Dynamic behavior of a masonry civic belfry under operational conditions

by Sara Casciati

Casciati S. and Al-Saleh R. (2010). “Dynamic behavior of a masonry civic belfry under operational conditions”. Acta Mechanica, 215(1-4), 211-224. ISSN: 0001-5970.

DATE AND PLACE OF PUBLICATION: December 2010; Springer Wien, A-1201 Wien, Austria.

ABSTRACT: Slender structures, such as towers, are characterized by a high sensitivity to dynamic excitation. As a... more ABSTRACT: Slender structures, such as towers, are characterized by a high sensitivity to dynamic excitation. As a consequence, meaningful information about their behavior under operational conditions can be obtained by monitoring their response to ambient vibrations. Furthermore, significant stresses could be induced to the ancient masonry walls when the dynamic forces due to the swinging of a bell are acting. To assess the structural conditions of a case study representative of such type of structures and to plan an adequate retrofit, numerical analyses are carried out on a model whose modal parameters are calibrated based on the elaboration of the results from the ambient vibrations tests. In particular, full time histories analyses are performed using as input either the signal recorded while the bell was hit by a hammer, or the numerically calculated dynamic forces that would be produced by the actual swinging of the bell. The first set of analyses aims to investigate the capability of an equivalent linear elastic model to capture the actual dynamic response of the structure. The second set of analyses provides an evaluation of the tower response when dynamic loads of higher intensity and likely occurrence are considered.

Experimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures

by Sara Casciati

Casciati S. and Hamdaoui K. (2008). “Experimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures”. Smart Structures and Systems, 4(2), 153-169. ISSN: 1738-1584.

DATA E LUOGO DI PUBBLICAZIONE: March 2008; Techno-Press, Daejeon 305-600, South Korea.

ABSTRACT: The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is... more ABSTRACT: The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is investigated. A small wall, serving as a prototype masonry specimen, is constructed to undergo a series of shaking table tests. It is first studied in its original state, and its dynamic characteristics (in terms of modal frequencies) are extracted from the recorded signals. The results are then compared with those obtained when an increasing number of couples of pre-stressed SMA wires are introduced in the specimen to link the bricks together. A threedimensional finite element model of the specimen is developed and calibrated according to the modal parameters identified from each experimental test (with and without SMA wires). The calibration process is conducted by enhancing the masonry mechanical behaviour. The results and the effectiveness of the approach are presented.

KEYWORDS: masonry; numerical modelling; shaking table tests; shape memory alloys; system identification.

Stiffness identification and damage localization via differential evolution algorithms

by Sara Casciati

Casciati S. (2008). “Stiffness identification and damage localization via differential evolution algorithms”. Structural Control & Health Monitoring, 15(3), 436-449. ISSN: 1545-2255.

DATA E LUOGO DI PUBBLICAZIONE: April 2008; John Wiley & Sons, Ltd., Chichester PO19 8SQ, W Sussex, England.

ABSTRACT. The goal of structural health monitoring is to identify which discrepancies between the actual behaviour of... more ABSTRACT. The goal of structural health monitoring is to identify which discrepancies between the actual behaviour of a structure and its reference undamaged state are indicative of damage. For this purpose, an objective function, which minimizes the difference between the measured and theoretical modal characteristics of the structure, is formulated. By selecting the stiffness parameters as optimization variables, a differential evolution algorithm is applied to create successive generations that better reflect the measured response, until a certain tolerance is met. At each step of the algorithm, the current modal parameters are recalculated from the new generation of stiffness matrices to estimate the value of the objective function. This procedure represents a favourable path to solve the so-called ‘inverse problem’. Furthermore, the comparison of the identified stiffness matrix with the initial one allows for damage detection and localization. A numerical example, where a generic structure is discretized into finite elements, is provided.

KEYWORDS: damage; element stiffness matrix; differential evolution algorithm; finite element analyses; modal parameters; objective function; optimization problem

Dynamics identification of industrial robots using contact force for the IDCS control

by Gentiane Venture

Statistical approach to a SHM benchmark problem

by Sara Casciati

Casciati S. (2010). “Statistical approach to a SHM benchmark problem”. Smart Structures and Systems, 6(1), 17-27. ISSN: 1738-1584.

DATE AND PLACE OF PUBLICATION: January 2010; Techno-Press, Daejeon 305-600, South Korea.

ABSTRACT: The approach to damage detection and localization adopted in this paper is based on a statistical comparison... more ABSTRACT: The approach to damage detection and localization adopted in this paper is based on a statistical comparison of models built from the response time histories collected at different stages during the structure lifetime. Some of these time histories are known to have been recorded when the structural system was undamaged. The consistency of the models associated to two different stages, both undamaged, is first recognized. By contrast, the method detects the discrepancies between the models from measurements collected for a damaged situation and for the undamaged reference situation. The damage detection and localization is pursued by a comparison of the SSE (sum of the squared errors) histograms. The validity of the proposed approach is tested by applying it to the analytical benchmark problem developed by the ASCE Task Group on Structural Health Monitoring (SHM). In the paper, the results of the benchmark studies are presented and the performance of the method is discussed.

KEYWORDS: damage detection; damage localization; regression analysis; structural health monitoring; sum of the squared errors.