| 1. |
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| 2. |
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| 3. |
- Churilov, Alexander, et al.
(författare)
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Mathematical model of non-basal testosterone regulation in the male by pulse modulated feedback
- 2009
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:1, s. 78-85
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Tidskriftsartikel (refereegranskat)abstract
- A parsimonious mathematical model of pulse modulated regulation of non-basal testosterone secretion in the male is developed. The model is of the third differential order, reflecting the three most significant hormones in the regulation loop, but is yet shown to be capable of sustaining periodic solutions with one or two pulses of gonadotropin-releasing hormone (GnRH) in each period. Lack of stable periodic solutions is otherwise a main shortcoming of existing low-order hormone regulation models. Existence and stability of periodic solutions are studied. The periodic mode with two GnRH pulses in the least period has not been described in medical literature, but is found to explain experimental data well.
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| 4. |
- Churilov, Alexander, et al.
(författare)
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Mathematical Model of Non-Basal Testosterone Regulation in the Male by Pulse Modulated Feedback
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A parsimonious mathematical model of pulse modulated regulation of non-basal testosterone secretion in the male is developed. The model is of third differential order, reflecting the three most significant hormones in the regulation loop, but is yet shown to be capable of sustaining periodic solutions with one or two pulses of gonadotropin-releasing hormone (GnRH) on each period. Lack of stable periodic solutions is otherwise a main shortcoming of existing low-order hormone regulation models. Existence and stability of periodic solutions are studied. The periodic mode with two GnRH pulses on the least period has not been described in medical literature but is found to explain experimental data well.
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| 5. |
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| 6. |
- Churilov, Alexander N., et al.
(författare)
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An impulse-to-impulse discrete-time mapping for a time-delay impulsive system
- 2014
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 50:8, s. 2187-2190
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that an impulsive system with a time-delay in the continuous part can be equivalently represented by discrete dynamics under less restrictive conditions on the time-delay value than considered previously.
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| 7. |
- Churilov, Alexander N., et al.
(författare)
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Delay-induced Dynamical Phenomena in Impulsive Goodwin's Oscillator : What We Know So Far
- 2015
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Ingår i: 2015 54Th Ieee Conference On Decision And Control (CDC). - 9781479978861 ; , s. 590-595
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Konferensbidrag (refereegranskat)abstract
- Impulsive Goodwin's oscillator model is introduced to capture the dynamics of sustained periodic processes in endocrine systems controlled by episodic pulses of hormones. The model is hybrid and comprises a continuous subsystem describing the hormone concentrations operating under a discrete pulse-modulated feedback implemented by firing neurons. Time delays appear in mathematical models of endocrine systems due to the significant transport phenomena but also because of the time necessary to produce releasable hormone quantities. From a biological point of view, the neural control should be robust against the time delay to ensure the loop functionality over a wide range of inter-individual variability. The paper provides an overview of the currently available results and contributes a generalization of a Poincare mapping approach to study complex dynamics of impulsive Goodwin oscillator. Both pointwise and distributed time delays are considered in a general framework based on the Poincare mapping. Bifurcation analysis is utilized to illustrate the analytical results.
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| 8. |
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| 9. |
- Churilov, Alexander N., et al.
(författare)
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Discrete-time mapping for an impulsive Goodwin oscillator with three delays
- 2017
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Ingår i: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering. - 0218-1274. ; 27:12
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Tidskriftsartikel (refereegranskat)abstract
- A popular biomathematics model of the Goodwin oscillator has been previously generalized to a more biologically plausible construct by introducing three time delays to portray the transport phenomena arising due to the spatial distribution of the model states. The present paper addresses a similar conversion of an impulsive version of the Goodwin oscillator that has found application in mathematical modeling, e.g. in endocrine systems with pulsatile hormone secretion. While the cascade structure of the linear continuous part pertinent to the Goodwin oscillator is preserved in the impulsive Goodwin oscillator, the static nonlinear feedback of the former is substituted with a pulse modulation mechanism thus resulting in hybrid dynamics of the closed-loop system. To facilitate the analysis of the mathematical model under investigation, a discrete mapping propagating the continuous state variables through the firing times of the impulsive feedback is derived. Due to the presence of multiple time delays in the considered model, previously developed mapping derivation approaches are not applicable here and a novel technique is proposed and applied. The mapping captures the dynamics of the original hybrid system and is instrumental in studying complex nonlinear phenomena arising in the impulsive Goodwin oscillator. A simulation example is presented to demonstrate the utility of the proposed approach in bifurcation analysis.
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| 10. |
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| 11. |
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| 12. |
- de Jong, Yde, et al.
(författare)
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PESI - a taxonomic backbone for Europe
- 2015
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Ingår i: Biodiversity Data Journal. - 1314-2836 .- 1314-2828. ; 3, s. 1-51
-
Tidskriftsartikel (refereegranskat)abstract
- Reliable taxonomy underpins communication in all of biology, not least nature conservation and sustainable use of ecosystem resources. The flexibility of taxonomic interpretations, however, presents a serious challenge for end-users of taxonomic concepts. Users need standardised and continuously harmonised taxonomic reference systems, as well as high-quality and complete taxonomic data sets, but these are generally lacking for non-specialists. The solution is in dynamic, expertly curated web-based taxonomic tools.The Pan-European Species-directories Infrastructure (PESI) worked to solve this key issue by providing a taxonomic e-infrastructure for Europe. It strengthened the relevant social (expertise) and information (standards, data and technical) capacities of five major community networks on taxonomic indexing in Europe, which is essential for proper biodiversity assessment and monitoring activities. The key objectives of PESI were: 1) standardisation in taxonomic reference systems, 2) enhancement of the quality and completeness of taxonomic data sets and 3) creation of integrated access to taxonomic information.This paper describes the results of PESI and its future prospects, including the involvement in major European biodiversity informatics initiatives and programs.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Sololov, Bods M., et al.
(författare)
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The Control of the Top Blown Oxygen Converter Process
- 2001
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Ingår i: Elsevier IFAC Publications / IFAC Proceedings series. - 1474-6670. - 0080435602 ; 34:6, s. 1331-1335
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the control of the top blown oxygen converter process by exploiting the static equations of the process in order to compensate for measured disturbances. The dissipation region of the controller is evaluated. A nonlinear observer is introduced for estimating the metal analysis in real time. It is shown that the observer is asymptotically stable and a region of attraction, where the estimation error converges, is derived
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| 19. |
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| 20. |
- Yamalova, Diana, et al.
(författare)
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Finite-dimensional hybrid observer for delayed impulsive model of testosterone regulation
- 2015
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Ingår i: Mathematical problems in engineering (Print). - : Hindawi Limited. - 1024-123X .- 1563-5147. ; 2015, s. 190463:1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The paper deals with the model-based estimation of hormone concentrations that are inaccessible for direct measurement in the blood stream. Previous research demonstrated that the dynamics of nonbasal endocrine regulation can be closely captured by linear continuous models with time delays under a pulse-modulated feedback. The presence of continuous time delays is inevitable in such a model due to transport phenomena and the time necessary for an endocrine gland to produce a certain hormone quantity. Yet, thanks to the finite-dimensional reducibility of the linear time-delay part of the system, a finite-dimensional model can be used to reconstruct both the continuous and discrete states of the hybrid time-delay plant. A hybrid observer exploiting this possibility is suggested and analyzed by means of a discrete impulse-to-impulse mapping.
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| 21. |
- Yamalova, Diana, et al.
(författare)
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Hybrid Observer for an Intrinsic Impulsive Feedback System
- 2017
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Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 50:1, s. 4570-4575
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with continuous plants subject to intrinsic pulse-modulated feedback, thus exhibiting hybrid closed-loop dynamics. The system structure implements a hybrid oscillator and arises in living organisms, e.g. when episodically firing neurons control the production of hormones in endocrine glands. Hybrid observers reconstructing both the continuous and discrete states of the hybrid plant from only continuous measured outputs are considered. They excel over the existing solutions through the introduction of two co-ordinated feedbacks of the output estimation error: one correcting the continuous state estimates and another adjusting the discrete ones. Different types of the feedback operator to the discrete estimates are analyzed. The observer design problem is reduced to synchronization of the observer solution with that of the plant. The synchronous mode of the observer is rendered locally stable by the selection of the feedback gains. Numerical illustration of the design procedure and observer performance with respect to a pulse-modulated model of testosterone regulation is provided.
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| 22. |
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| 23. |
- Yamalova, Diana, et al.
(författare)
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Hybrid state observer with modulated correction for periodic systems under intrinsic impulsive feedback
- 2013
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Konferensbidrag (refereegranskat)abstract
- A new observer structure for hybrid systems comprised of a linear time-invariant subsystem and immeasurable (intrinsic) impulsive feedback is suggested. It brings about significant improvements in the state estimation error settling time in comparison with that of an earlier considered static feedback observer by making use of the weighted output estimation error in the calculation of the discrete part of the observer.
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| 24. |
- Yamalova, Diana, et al.
(författare)
-
State estimation in a delayed impulsive model of testosterone regulation by a finite-dimensional hybrid observer
- 2015
-
Ingår i: Proc. 14th European Control Conference. - : IEEE. - 9783952426937 ; , s. 1450-1455
-
Konferensbidrag (refereegranskat)abstract
- The paper deals with the model-based estimation of hormone concentrations that are unaccessible for direct measurement in the blood stream. Previous research demonstrated that the dynamics of non-basal endocrine regulation can be closely captured by linear continuous models with time delays under a pulse-modulated feedback. The presence of continuous time delays is inevitable in such a model due to transport phenomena and the time necessary for an endocrine gland to produce a certain hormone quantity. Yet, thanks to the Finite-Dimensional reducibility of the linear time-delay part of the system, a finite-dimensional model can be used to reconstruct both the continuous and discrete states of the hybrid time-delay plant. A hybrid observer exploiting this possibility is suggested and analyzed by means of a discrete impulse-to-impulse mapping.
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| 25. |
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| 26. |
- Zhusubaliyev, Zhanybai T., et al.
(författare)
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Bifurcation phenomena in an impulsive model of non-basal testosterone regulation
- 2012
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Ingår i: Chaos. - : AIP Publishing. - 1054-1500 .- 1089-7682. ; 22:1, s. 013121-
-
Tidskriftsartikel (refereegranskat)abstract
- Complex nonlinear dynamics in a recent mathematical model of non-basal testosterone regulation are investigated. In agreement with biological evidence, the pulsatile (non-basal) secretion of testosterone is modeled by frequency and amplitude modulated feedback. It is shown that, in addition to already known periodic motions with one and two pulses in the least period of a closed-loop system solution, cycles of higher periodicity and chaos are present in the model in hand. The broad range of exhibited dynamic behaviors makes the model highly promising in model-based signal processing of hormone data.
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| 27. |
- Zhusubaliyev, Zhanybai T., et al.
(författare)
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Multistability and hidden attractors in an impulsive Goodwin oscillator with time delay
- 2015
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Ingår i: The European Physical Journal Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 224:8, s. 1519-1539
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Tidskriftsartikel (refereegranskat)abstract
- The release of luteinizing hormone (LH) is driven by intermittent bursts of activity in the hypothalamic nerve centers of the brain. Luteinizing hormone again stimulates release of the male sex hormone testosterone (Te) and, via the circulating concentration of Te, the hypothalamic nerve centers are subject to a negative feedback regulation that is capable of modifying the intermittent bursts into more regular pulse trains. Bifurcation analysis of a hybrid model that attempts to integrate the intermittent bursting activity with a continuous hormone secretion has recently demonstrated a number of interesting nonlinear dynamic phenomena, including bistability and deterministic chaos. The present paper focuses on the additional complexity that arises when the time delay in the continuous part of the model exceeds the typical bursting interval of the feedback. Under these conditions, the hybrid model is capable of displaying quasiperiodicity and border collisions as well as multistability and hidden attractors.
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| 28. |
- Zhusubaliyev, Zhanybai T., et al.
(författare)
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Time Delay Induced Multistability and Complex Dynamics in an Impulsive Model of Endocrine Regulation
- 2014
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Ingår i: 2014 European Control Conference (ECC). - 9783952426913 ; , s. 2304-2309
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Konferensbidrag (refereegranskat)abstract
- The effects caused by the introduction of a time delay in the continuous part of an impulsive (hybrid) model of endocrine feedback regulation are studied by bifurcation analysis. It is concluded that larger (in some well-defined sense) values of the time delay give rise to a broad range of nonlinear dynamics phenomena that have not been observed for the smaller ones. Among such behaviors are e.g. border-collision bifurcations, bistability, and quasiperiodic solutions. The reason for the more complex dynamics exhibited by the model in this case is a discontinuity of the Jacobian of a discrete mapping describing the propagation of the model dynamics from one firing of the impulsive feedback to another.
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| 29. |
- Abdalmoaty, Mohamed, 1986-, et al.
(författare)
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Continuous Time-Delay Estimation From Sampled Measurements
- 2023
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Ingår i: IFAC-PapersOnLine. - : Elsevier. - 2405-8963. ; 56:2, s. 6982-6987
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Tidskriftsartikel (refereegranskat)abstract
- An algorithm for continuous time-delay estimation from sampled output data and a known input of finite energy is presented. The continuous time-delay modeling allows for the estimation of subsample delays. The proposed estimation algorithm consists of two steps. First, the continuous Laguerre spectrum of the output (delayed) signal is estimated from discretetime (sampled) noisy measurements. Second, an estimate of the delay value is obtained via a Laguerre domain model using a continuous-time description of the input. The second step of the algorithm is shown to be intrinsically biased, the bias sources are established, and the bias itself is modeled. The proposed delay estimation approach is compared in a Monte-Carlo simulation with state-of-the-art methods implemented in time, frequency, and Laguerre domain demonstrating comparable or higher accuracy in the considered scenario.
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| 30. |
- Abdalmoaty, Mohamed, 1986-, et al.
(författare)
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Noise reduction in Laguerre-domain discrete delay estimation
- 2022
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Ingår i: 2022 IEEE 61st Conference on Decision and Control (CDC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665467612 - 9781665467605 - 9781665467629 ; , s. 6254-6259
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces a stochastic framework for a recently proposed discrete-time delay estimation method in Laguerre-domain, i.e. with the delay block input and output signals being represented by the corresponding Laguerre series. A novel Laguerre-domain disturbance model allowing the involved signals to be square-summable sequences is devised. The relation to two commonly used time-domain disturbance models is clarified. Furthermore, by forming the input signal in a certain way, the signal shape of an additive output disturbance can be estimated and utilized for noise reduction. It is demonstrated that a significant improvement in the delay estimation error is achieved when the noise sequence is correlated. The noise reduction approach is applicable to other Laguerre-domain problems than pure delay estimation.
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| 31. |
- Aghanavesi, Somayeh, 1981-, et al.
(författare)
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A multiple motion sensors index for motor state quantification in Parkinson's disease
- 2020
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Ingår i: Computer Methods and Programs in Biomedicine. - : Elsevier BV. - 0169-2607 .- 1872-7565. ; 189
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: To construct a Treatment Response Index from Multiple Sensors (TRIMS) for quantification of motor state in patients with Parkinson's disease (PD) during a single levodopa dose. Another aim was to compare TRIMS to sensor indexes derived from individual motor tasks. Method: Nineteen PD patients performed three motor tests including leg agility, pronation-supination movement of hands, and walking in a clinic while wearing inertial measurement unit sensors on their wrists and ankles. They performed the tests repeatedly before and after taking 150% of their individual oral levodopa-carbidopa equivalent morning dose.Three neurologists blinded to treatment status, viewed patients’ videos and rated their motor symptoms, dyskinesia, overall motor state based on selected items of Unified PD Rating Scale (UPDRS) part III, Dyskinesia scale, and Treatment Response Scale (TRS). To build TRIMS, out of initially 178 extracted features from upper- and lower-limbs data, 39 features were selected by stepwise regression method and were used as input to support vector machines to be mapped to mean reference TRS scores using 10-fold cross-validation method. Test-retest reliability, responsiveness to medication, and correlation to TRS as well as other UPDRS items were evaluated for TRIMS. Results: The correlation of TRIMS with TRS was 0.93. TRIMS had good test-retest reliability (ICC = 0.83). Responsiveness of the TRIMS to medication was good compared to TRS indicating its power in capturing the treatment effects. TRIMS was highly correlated to dyskinesia (R = 0.85), bradykinesia (R = 0.84) and gait (R = 0.79) UPDRS items. Correlation of sensor index from the upper-limb to TRS was 0.89. Conclusion: Using the fusion of upper- and lower-limbs sensor data to construct TRIMS provided accurate PD motor states estimation and responsive to treatment. In addition, quantification of upper-limb sensor data during walking test provided strong results. © 2019
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| 32. |
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| 33. |
- Albaba, Adnan, et al.
(författare)
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Online Model-Based Beat-by-beat Heart Rate Estimation
- 2020
-
Ingår i: 2020 American Control Conference (ACC). - 9781538682661 - 9781538682678 - 9781538682654 ; , s. 539-544
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Konferensbidrag (refereegranskat)abstract
- A method for estimating the instantaneous heart rate (HR) using the morphological features of one electrocardiogram (ECG) cycle (beat) at a time is proposed. This work is not aimed at introducing an alternative way for HR estimation, but rather illustrates the utility of model-based ECG analysis in online individualized monitoring of the heart function. The HR estimation problem is reduced to fitting one parameter, whose value is related to the nine parameters of a realistic nonlinear model of the ECG and estimated from data by nonlinear least-squares optimization. The method feasibility is evaluated on synthetic ECG signals as well as signals acquired from MIT-BIH databases at Physionet website. Moreover, the performance of the method was tested under realistic free-moving conditions using a wearable ECG and HR monitor with encouraging results.
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| 34. |
- Albaba, Adnan, et al.
(författare)
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Patient-Specific Electrocardiogram Monitoring by Model-Based Stochastic Anomaly Detection
- 2020
-
Ingår i: 2020 European Control Conference (ECC). - 9783907144022 - 9781728188133 ; , s. 735-740
-
Konferensbidrag (refereegranskat)abstract
- A novel model-based method for patient-specific detection of deformed electrocardiogram (ECG) beats is proposed and tested. Five parameters of a patient-specific nonlinear ECG model are estimated from data by nonlinear least-squares optimization. The normal variability of the model parameters is captured by estimated probability density functions. A binary classifier, based on stochastic anomaly detection methods, along with a pre-tuned classification threshold, is employed for detecting the abnormal ECG beats. We demonstrate the utility of the proposed approach by validating it on annotated arrhythmia data recorded under clinical conditions.
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| 35. |
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| 36. |
- Artemov, A. N., et al.
(författare)
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Large effect of thermal processes on the susceptibility of YBCO film with transport current
- 2004
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Ingår i: Physica. C, Superconductivity. - : Elsevier BV. - 0921-4534 .- 1873-2143. ; 403:3, s. 157-162
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Tidskriftsartikel (refereegranskat)abstract
- The response of YBCO film with transport current to the weak alternating magnetic field was studied. The hysteresis of the temperature dependences of the response measured under cooling and heating was revealed. The qualitative explanation of this phenomenon is proposed. It is based on the fact that under certain conditions the superconductor with transport current has two steady states. It is found that the hysteresis arises only if transport current exceeds some finite value I-0.
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| 37. |
- Bask, Michael, et al.
(författare)
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Analysis of least-squares state estimators for a harmonic oscillator
- 2000
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Ingår i: Proceedings of the 39th IEEE Conference on Decision and Control. - Piscataway, NJ : IEEE Communications Society. - 0780366387 ; , s. 3819-3824
-
Konferensbidrag (refereegranskat)abstract
- The concept of least-squares observer is revisited. Robustness properties of this class of observers with respect to norm-bounded measurement noise are investigated and shown to be very much dependent on the operator chosen for the observer implementation. For the case of a harmonic oscillator, an explicit observer parameterization in terms of the implementation operator and the oscillator frequency is obtained, and observer's existence conditions are proven and analyzed
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| 38. |
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| 39. |
- Bask, Michael, et al.
(författare)
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External model repetitive controller for active vibration isolation
- 1999
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Ingår i: Proceedings of Active 99. - Washington, DC : Institute of noise control engineering. - 0962207225 ; , s. 177-188
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the External Model Repetitive Controller, a structure that combines the classical repetitive disturbance model (in the form of a time delay with a unit feedback) with a feedback of a disturbance estimate. The latter is often termed the External Model Controller and has a broad spectrum of technical applications, e.g., active vibration control. By analyzing the controller performance under the assumption of a disturbance period modeling error, it is shown that an unacceptable performance degradation might occur even for very small values of the modeling error
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| 40. |
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| 41. |
- Birk, Wolfgang, et al.
(författare)
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A note on gramian-based interaction measures
- 2003
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Ingår i: Proceedings, European Control Conference.
-
Konferensbidrag (refereegranskat)abstract
- This note deals with recently developed gramian based interaction measures. The measures are used for the choice of measurement/actuator pairs for decentralized control, where the controller remains unspecified. The theoretical background of these measures is clarified and a geometrical interpretation is given. Moreover, a generalization of the Hankel interaction index array to different gramian based system norms is proposed and it is shown that the introduction of weighted gramians makes the criteria more flexible and superior compared to the augmenting with additional filter dynamics. Finally, some examples are given to illustrate the usefulness of the generalized measures.
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| 42. |
- Birk, Wolfgang, et al.
(författare)
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Control and gas leakage detection in a fine coal injection plant : design and experiments
- 1998
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Ingår i: Automation in mining, mineral, and metal processing 1998, (MMM'98). - Oxford : Pergamon Press. ; , s. 261-266
-
Konferensbidrag (refereegranskat)abstract
- This paper deals with design and implementation of a combined model-based control and gas leakage detection system applied to the pulverized coal injection plant at SSAB Tunnplåt AB in Luleå, Sweden. The structure and functions of the in-house control and process monitoring system SafePCI are described. SafePCI is experimentally tested and has successfully completed two weeks test operation. The evaluation of the test operation indicate that combined model-based control and gas leakage detection is a major improvement for control systems in the process industry.
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| 43. |
- Birk, Wolfgang, et al.
(författare)
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Foam level control in a water model of the LD converter process
- 2001
-
Ingår i: Automation in mining, mineral, and metal processing 2001. - Oxford : Published for the International Federation of Automatic Control by Pergamon. - 1474-6670. - 0080436927
-
Konferensbidrag (refereegranskat)abstract
- This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.
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| 44. |
- Birk, Wolfgang, et al.
(författare)
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Foam level control in a water model of the LD converter process
- 2003
-
Ingår i: Control Engineering Practice. - 0967-0661 .- 1873-6939. ; 11:1, s. 49-56
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.
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| 45. |
- Birk, Wolfgang, et al.
(författare)
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Implementation and industrial experiences of advanced control and monitoring in coal injection
- 2000
-
Ingår i: Control Engineering Practice. - 0967-0661 .- 1873-6939. ; 8:3, s. 327-335
-
Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the implementation and industrial experiences of a model-based control and gas-leakage detection system in a coal injection plant. It describes how advanced control and monitoring can be implemented in an industrial environment while taking human–machine interface aspects into consideration. The operation of the advanced and the conventional concept are compared regarding evaluation data, experiences and observations of operators and maintenance personnel. It is shown that the advanced control and monitoring system improves plant performance without disturbing routines in plant operation and, moreover, is positively accepted by the plant operators.
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| 46. |
- Birk, Wolfgang, et al.
(författare)
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Model-based estimation of molten metal analysis in the LD converter : experiments at SSAB Tunnplat AB in Lulea
- 2001
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Ingår i: Conference record of the 2001 IEEE Industry Applications Conference. - Piscataway, NJ : IEEE Communications Society. ; , s. 1349-1353
-
Konferensbidrag (refereegranskat)abstract
- Experiences from field tests of a model-based molten metal analysis estimation system for the LD converter process are reported. Experiments have been carried out during a six-months long period on two converters at SSAB Tunnplat AB in Lulea, Sweden. The results achieved prove the viability of the approach taken and indicate its high potential regarding estimation accuracy and robustness. It is also concluded that some further system development is necessary to enable modeling of additives and lance level before the system can be recommended for permanent installation
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| 47. |
- Birk, Wolfgang, et al.
(författare)
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Model-based estimation of molten metal analysis in the LD converter : experiments at SSAB Tunnplat AB in Lulea
- 2002
-
Ingår i: IEEE transactions on industry applications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-9994 .- 1939-9367. ; 38:2, s. 565-570
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Tidskriftsartikel (refereegranskat)abstract
- Experiences from field tests of a model-based molten metal analysis estimation system for the Linz and Donawitz converter process are reported. Experiments have been carried out during a six-month-long period on two converters at SSAB Tunnplat AB, Lulea, Sweden. The achieved results prove viability of the approach taken and indicate its high potential regarding estimation accuracy and robustness. It is also concluded that some further system development is necessary to enable modeling of additives and lance level before the system can be recommended for permanent installation
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| 48. |
- Birk, Wolfgang, et al.
(författare)
-
Physical modeling and control of dynamic foaming in an LD-converter process
- 2001
-
Ingår i: IEEE transactions on industry applications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-9994 .- 1939-9367. ; 37:4, s. 1067-1073
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with physical modeling and control of dynamic foaming in the LD-converter process. An experimental setup consisting of a water model, digital signal processor, and PC hardware is built and shown to be useful for studying dynamic foaming. Furthermore, a foam height estimation algorithm is presented and validated through experiments. Finally, sound signals from the LD-converter and water model are compared and similarities between them are found.
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| 49. |
- Birk, Wolfgang, et al.
(författare)
-
Physical modelling and control of dynamic foaming in an LD-converter process
- 2000
-
Ingår i: Conference record of the 2000 IEEE Industry Applications Conference. - Piscataway, NJ : IEEE Communications Society. - 0780364015 ; , s. 2584-2590
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Konferensbidrag (refereegranskat)abstract
- This paper deals with physical modelling and control of dynamic foaming in the LD-converter process. An experimental setup consisting of a water model, DSP and PC hardware is built up and shown to be useful for studying dynamic foaming. Furthermore, a foam height estimation algorithm is presented and validated through experiments. Finally, sound signals from the LD-converter and water model are compared and similarities between them are found.
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| 50. |
- Birk, Wolfgang, et al.
(författare)
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Pressure and flow control of a pulverized coal injection vessel
- 1997
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Ingår i: Proceedings of the 1997 IEEE International Conference on Control Applications. - Piscataway, NJ : IEEE Communications Society. - 0780338774 ; , s. 127-132
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Konferensbidrag (refereegranskat)abstract
- Deals with model-based pressure and flow control of a fine coal injection vessel for the use of the blast furnace injection process. By means of system modeling and identification, the structure and behavior of the coal injection vessel are analyzed. It is shown that by use of model-based design, the control goals can be reached and the control performance can be significantly improved compared to the conventional PI-controllers. Several dynamic models of the plant are developed. A number of control strategies are presented and compared by means of practical tests. The LQG design method is used to design the controllers. All the controllers are validated through experiments on the coal injection plant at SSAB Tunnplat in Lulea, Sweden
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