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1

Comparative study of the efficiency, effectiveness and robustness of the TGE S.A. Day-Ahead Market model and system

Marlęga Radosław, Tchórzewski Jerzy

Studia Informatica : systems and information technology

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2023

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Vol. 1(28)

29--45

EN

The article contains selected results of comparative research on the quality of the parametric model, corrected in selected situations with the use of ANN and the Day-Ahead Market system of TGE S.A. carried out in MATLAB and Simulink. The System Identification Toolbox library was used for identification tests and Simulink for simulation and comparative tests. The comparative studies used such measures of model and system quality as: efficiency, effectiveness and robustness. Their waveforms as well as their average values and absolute errors and relative errors between the identification model or the identification-neural model and the system were obtained. The results of general tests were shown for the hours: 6:00, 12:00, 18:00 and 24:00 in 2019, and the detailed tests for 6:00. The sensitivity of the waveforms obtained in terms of model quality and the Day-Ahead Market system was also tested, depending on the assumed values of such parameters as e.g. electricity volume or volume-weighted average price of electricity.

2

Prototyp ekstremalnie modularnego hiperredundantnego manipulatora Arm-Z

Zawidzka Ela, Zawidzki Machi, Kiński Wojciech

Pomiary Automatyka Robotyka

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2023

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R. 27, nr 1

39--44

PL

Arm-Z to koncepcja hiperredundantnego manipulatora robotycznego składającego się z przystających modułów o jednym stopniu swobody (1-DOF) i realizującego (prawie) dowolne ruchy w przestrzeni. Zasadnicze zalety Arm-Z to: ekonomizacja (dzięki masowej produkcji identycznych elementów) oraz odporność na awarie (po pierwsze - zepsute moduły mogą być łatwo zastąpione, po drugie - nawet gdy jeden lub więcej modułów ulegnie awarii - manipulator taki może ciągle wykonywać, prawdopodobnie w stopniu ograniczonym, zakładane zadania). Podstawową wadą systemu Arm-Z jest jego nieintuicyjne, bardzo trudne sterowanie. Innymi słowy, połączenie koncepcji nietrywialnego modułu z formowaniem praktycznych konstrukcji oraz sterowanie ich rekonfiguracją (transformacją ze stanu A do B) są bardzo złożone obliczeniowo. Mimo to, prezentowane podejście jest racjonalne, zważywszy powszechną dostępność wielkich mocy obliczeniowych w kontraście z wysokimi kosztami i „delikatnością” niestandardowych rozwiązań i urządzeń. W artykule nakreślono ogólną koncepcję manipulatora Arm-Z i zaprezentowano wstępne prace zmierzające do wykonania prototypu.

EN

Arm-Z is a concept of a robotic manipulator comprised of linearly joined congruent modules with possibility of relative twist (1 DOF). The advantages of Arm-Z are: economization (mass-production) and robustness (modules which failed can be replaced, also if some fail the system can perform certain tasks). Non-intuitive and difficult control are the disadvantages of Arm-Z. In other words, the combination of non-trivial module shape with forming of practical modular structures and their control (from state A to B) is computationally expensive. However, due to availability of modern computational power, proposed here approach is rational and competitive, especially considering the high cost and sensitivity of non-standard solutions. This paper outlines the general concept of Arm-Z manipulator and presents preliminary work towards making a proof-of-the-concept prototype.

3

Singularity-robust inverse kinematics for serial manipulators

Dulęba Ignacy

Journal of Automation Mobile Robotics and Intelligent Systems

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2023

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Vol. 17, No. 3

38--45

EN

This paper is a practical guideline on how to analyze and evaluate the literature algorithms of singularity- robust inverse kinematics or to construct new ones. Additive, multiplicative, and based on the Singularity Value Decomposition (SVD) methods are examined to retrieve well-conditioning of a matrix to be inverted in the Newton algorithm of inverse kinematics. It is shown that singularity avoidance can be performed in two different, but equivalent, ways: either via properly modified manipulability matrix or not allowing the decrease of the minimal singular value below a given threshold. It is discussed which method can always be used and which can only be used when some pre‐conditions are met. Selected methods are compared to with respect to the efficiency of coping with singularities based on a theoretical analysis as well as simulation results. Also, some questions important for mathematically and/or practically oriented roboticians are stated and answered.

4

Robust microgrids for distribution systems with high solar photovoltaic penetration

Ediriweera W.E.P. Sampath, Lidula N.W.A., Herath H. Dayan B.P.

Archives of Electrical Engineering

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2023

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Vol. 72, nr 3

785--809

EN

A microgrid is an appropriate concept for urban areas with high penetration of renewable power generation, which improves the reliability and efficiency of the distribution network at the consumer premises to meet various loads such as domestic, industrial, and agricultural types. Microgrids comprising inverter-based and synchronous generator-based distribution generators can lead to the instability of the system during the islanded mode of operation. This paper presents a study on designing stable microgrids to facilitate higher penetration of solar power generation into a distribution network. A generalized small signal model is derived for a microgrid with static loads, dynamic loads, energy storages, solar photovoltaic (PV) systems, and diesel generators, incorporating the features of dynamic systems. The model is validated by comparing the transient curves given by the model and a transient simulator subjected to step changes. The result shows that full dynamic models of complex systems of microgrids can be built accurately, and the proposed microgrid is stable for all the considered loading situations and solar PV penetration levels according to the small signal stability analysis.

5

A model-free direct predictive grid-current control strategy for grid-connected converter with an inductance-capacitance-inductance filter

Guo Leilei, Zheng Mingzhe, Yu Changzhou, Xu Haizhen, Li Yanyan

Archives of Electrical Engineering

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2023

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Vol. 72, nr 1

23--42

EN

The disadvantages of the conventional model predictive current control method for the grid-connected converter (GCC) with an inductance-capacitance-inductance (LCL) filter are a large amount of calculation and poor parameter robustness. Once parameters of the model are mismatched, the control accuracy of model predictive control (MPC) will be reduced, which will seriously affect the power quality of the GCC. The article intuitively analyzes the sensitivity of parameter mismatch on the current predictive control of the conventional LCL-filtered GCC. In order to solve these issues, a model-free predictive current control (MFPCC) method for the LCL-filtered GCC is proposed in this paper. The contribution of this work is that a novel current predictive robust controller for the LCL-filtered GCC is designed based on the principle of the ultra-local model of a single input single output system. The proposed control method does not require using any model parameters in the controller, which can effectively suppress the disturbances of the uncertain parameter variations. Compared with conventional MPC, the proposed MFPCC has smaller current total harmonic distortion (THD). When the filter parameters are mismatched, the control error of the proposed method is smaller. Finally, a comparative experimental study is carried out on the platform of Typhoon and PE-Expert4 to verify the superiority and effectiveness of the proposed MFPCC method for the LCL-filtered GCC.

6

On the robustness of the integrable trajectories of the control systems with limited control resources

Huseyin Nesir, Huseyin Anar, Guseinov Khalik G.

Archives of Control Sciences

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2023

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Vol. 33, No. 3

527--537

EN

The control system described by Urysohn type integral equation is considered where the system is nonlinear with respect to the phase vector and is affine with respect to the control vector. The control functions are chosen from the closed ball of the space Lq(Ω; ℝm), q > 1, with radius r and centered at the origin. The trajectory of the system is defined as p-integrable multivariable function from the space Lp(Ω; ℝn), (1/q) + (1/p) = 1, satisfying the system’s equation almost everywhere. It is shown that the system’s trajectories are robust with respect to the fast consumption of the remaining control resource. Applying this result it is proved that every trajectory can be approximated by the trajectory obtained by full consumption of the total control resource.

7

Fractional order PIλDµA controller design based on Bode’s ideal function

Bettou Khalfa, Charef Abdelfatah

Archives of Control Sciences

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2023

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Vol. 33, No. 2

425--458

EN

The fractional order proportional, integral, derivative and acceleration (PIλDµA) controller is an extension of the classical PIDA controller with real rather than integer integration action order λ and differentiation action order µ. Because the orders λ and µ are real numbers, they will provide more flexibility in the feedback control design for a large range of control systems. The Bode’s ideal transfer function is largely adopted function in fractional control systems because of its iso-damping property which is an essential robustness factor. In this paper an analytical design technique of a fractional order PIλDµA controller is presented to achieve a desired closed loop system whose transfer function is the Bode’s ideal function. In this design method, the values of the six parameters of the fractional order PIλDµA controllers are calculated using only the measured step response of the process to be controlled. Some simulation examples for different third order motor models are presented to illustrate the benefits, the effectiveness and the usefulness of the proposed fractional order PIλDµA controller tuning technique. The simulation results of the closed loop system obtained by the fractional order PIλDµA controller are compared to those obtained by the classical PIDA controller with different design methods found in the literature. The simulation results also show a significant improvement in the closed loop system performances and robustness using the proposed fractional order PIλDµA controller design.

8

When to Trust AI: Advances and Challenges for Certification of Neural Networks

Kwiatkowska Marta, Zhang Xiyue

Annals of Computer Science and Information Systems

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2023

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Vol. 35

25--37

EN

Artificial intelligence (AI) has been advancing at a fast pace and it is now poised for deployment in a wide range of applications, such as autonomous systems, medical diagnosis and natural language processing. Early adoption of AI technology for real-world applications has not been without problems, particularly for neural networks, which may be unstable and susceptible to adversarial examples. In the longer term, appropriate safety assurance techniques need to be developed to reduce potential harm due to avoidable system failures and ensure trustworthiness. Focusing on certification and explainability, this paper provides an overview of techniques that have been developed to ensure safety of AI decisions and discusses future challenges.

9

Development and validation of RP HPLC method for the estimation of methyl paraben sodium and propyl paraben sodium in iron protein succinylate syrup

Javed Muhammad Faisal, Zahra Manzar, Javed Iqra, Ahmad Shahbaz, Jabeen Tayyaba, Ahmad Muhammad

Acta Chromatographica

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2023

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Vol. 35, no. 1

52--59

EN

A new precise, selective and reliable reversed phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of Methyl paraben sodium (MPS) and Propyl paraben sodium (PPS) (preservatives) in Iron protein succinylate syrup. Optimized conditions were; Methanol: Water (65: 35) as mobile phase, UV/Vis detector at the wavelength of 254 nm and flow rate was set at 1.3 ml min⁻¹. By applying the set of conditions, separation of components was carried out in less than 7 min for both the analytes. The method was validated according to International conference of Harmonization (ICH) guidelines and the analytical characteristic parameters of validation included specificity, limit of detection (LOD), limit of quantification, linearity, accuracy, precision and robustness were evaluated. The calibration curve was found to be linear in the range of 0.045 mg mL⁻¹ to 0.075 mg mL⁻¹ for Methyl paraben sodium and 0.015 mg mL⁻¹ to 0.025 mg mL⁻¹ for propyl paraben sodium with a correlation coefficient r2 > 0.999. Accuracy; reported as percentage recovery was found to be in the range of 98.71%–101.64% for Methyl paraben sodium and 99.85%–101.47% for Propyl paraben sodium at 80%, 100% and 120% concentration for both the analytes. The proposed method was found to be precise and robust when evaluated by variations in wavelength, mobile phase composition, temperature and analyst. The limit of detection (LOD) was found 0.001 mg mL⁻¹ (3 ppm) for Methyl paraben sodium and 0.001 mg mL⁻¹ (1 ppm) for Propyl paraben sodium.

10

Robust estimation of the spherical normal distribution

Castilla Elena

Mathematica Applicanda

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2022

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Vol. 50, no. 1

43--63

EN

This paper develops a new family of estimators, the minimum density power divergence estimators, for the parameters of the Spherical Normal Distribution. This family contains the maximum likelihood estimator as a particular case. The robustness is empirically illustrated through a Monte Carlo simulation study and two biological numerical examples. Tools needed to implement these methods are also provided.

PL

Artykuł przedstawia nową rodzinę estymatorów parametrów sferycznego rozkładu normalnego minimalnej dywergencji. Ta rodzina obejmuje estymator największej wiarygodności jako przypadek szczególny. Odporność tych estymatorów jest zilustrowana empirycznie przez badanie symulacyjne Monte Carlo. Zamieszczone przykłady dla danych rzeczywistych dotyczą zagadnień z biologii. Pokazano również narzędzia potrzebne do wdrożenia tych metod.

11

Experimental and theoretical study of the reinforced concrete flat slabs with the central support loss

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2022

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Nr 4

12--41

EN

The paper experimentally and theoretically considers the issues of assessing the robustness and resistance to progressive collapse of a flat slab with a sudden removal of the central support. The results of testing two scale models of a fragment of a flat ceiling in the case of removal of the central support under static (specimen FS-1) and dynamic (specimen FS-2) loading are presented and analyzed. A theoretical approach to the quantitative assessment of robustness was tested, which is based on the provisions of the energy balance of a damaged structural system in an accidental design situation.

12

Radioterapia protonowa. Cz. 4, Wstęp do planowania leczenia

Garbacz Magdalena, Foltyńska Gabriela, Rydygier Marzena, Krzempek Dawid, Kopeć Renata

Inżynier i Fizyk Medyczny

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2022

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Vol. 11, nr 4

269--34

PL

Planowanie leczenia w radioterapii protonowej w niektórych aspektach będzie różnić się od planowania z zastosowaniem wiązek fotonowych ze względu na różnice we właściwościach fizycznych obu tych wiązek. Występujący dla wiązek protonowych pik Bragga daje możliwość ograniczenia dawki za zmianą nowotworową, ale wpływa również na strategię wyboru wiązek, która będzie bezpieczna dla pacjenta. Pojawiają się również inne metody obliczeń dawki, techniki napromieniania pacjenta oraz optymalizacji planów leczenia. Narzędzia obliczeniowe rozkładów dawki stosowane w praktyce klinicznej muszą zapewniać dużą dokładność i zgodność obliczeń z danymi eksperymentalnymi w celu minimalizacji niepewności zasięgu wiązki protonowej. Obecne systemy do planowania leczenia w większości bazują na algorytmach analitycznych, ale pojawiają się również systemy oferujące symulacje transportu cząstek oparte o metody Monte Carlo. Dodatkowo kody transportu promieniowania pozwalają uwzględnić wpływ innych wielkości fizycznych na rozkład dawki, w tym względną skuteczność biologiczną wiązki protonowej. W niniejszej pracy zostaną przedstawione najważniejsze aspekty w planowaniu leczenia wiązkami protonowymi wraz z dyskusją aktualnych problemów i strategii ich rozwiązywania.

EN

Treatment planning in proton radiotherapy, in some aspects, will differ from planning with photon beams, due to differences in the physical properties of these two beams. The Bragg peak that occurs for proton beams provides an opportunity to reduce the dose behind the tumor, but it also affects the strategy for selecting beams that will be safe for the patient. Other methods of dose calculations, patient irradiation techniques and optimization of treatment plans are also appearing. Dose distribution calculation tools used in clinical practice must ensure high accuracy and compatibility of calculations with experimental data to minimize proton beam range uncertainty. Current treatment planning systems are mostly based on analytical algorithms, but systems offering particle transport simulations based on Monte Carlo methods are also being developed. In addition, radiation transport codes make it possible to take into account the influence of other physical quantities on dose distribution, including the relative biological effectiveness of the proton beam. This review will present the most important aspects in proton treatment planning, along with a discussion of current problems and strategies for solving them.

13

Proposal for application of risk analysis to assess robustness of floor slabs pre-stressed with unbonded tendoms

Woliński Szczepan, Pytlowany Tomasz

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

241--253

EN

The list of potential hazards related to concrete elements and structures prestressed with the use of unbonded tendons, including the flat slabs, is long and fairly well recognized. In addition to the standard accidental events this list includes: mishandling during construction, small fire, local corrosion, loss of bond at the anchorage, second order effects, brittle fracture of elements, etc. Despite of these hazards related to unbonded post-tensioning, this type of structures are extensively promoted and used in practice thanks to the possibility of the large span floors and innovative character of this technology. The paper presents a proposal for the application of risk analysis to assess the robustness of structures with flat slabs prestressed with unbonded tendons. The adoption of variables that determine risk and robustness as fuzzy numbers assigned to linguistic variables are proposed. Numerical example is presented to demonstrate risk and robustness assessment of building structure with unbonded post-tensioned slabs supported directly on columns.

PL

Lista potencjalnych zagrożen związanych z elementami i konstrukcjami betonowymi sprężonymi za pomocą cięgien bez przyczepności, w tym płyt płaskich, jest długa i dość dobrze rozpoznana. Chociaż w nowszych publikacjach formułowane są opinie, że obawy związane z zagrożeniami bezpieczeństwa i małą odpornością poawaryjną konstrukcji sprężonych cięgnami bez przyczepności po spełnieniu odpowiednich standardów projektowych i starannym wykonaniu są bezpodstawne, to ich uzasadnienie jest problematyczne. Poza standardowymi zdarzeniami losowymi lista ta obejmuje: błędy wykonawstwa, niewielki pożar, miejscową korozję cięgien sprężających, utratę przyczepności cięgien w zakotwieniach, efekty drugiego rzędu, kruche pękanie elementów itp. Tego rodzaju konstrukcje są szeroko promowane i wykorzystywane w praktyce dzięki możliwości konstruowania stropów o dużej rozpiętości oraz innowacyjnemu charakterowi tej technologii. W pracy przedstawiono propozycje zastosowania analizy ryzyka do oceny bezpieczeństwa konstrukcji stropów z płyt płaskich sprężonych cięgnami bez przyczepności. Proponuje się przyjęcie zdefiniowanych implicite wymagań wpływających na poziom ryzyka i odporność jako liczb rozmytych przypisanych odpowiednim zmiennym lingwistycznym. Przedstawiono przykład liczbowy oceny ryzyka i nośności ustroju słupowo-płytowego z płaskimi płytami sprężonymi płaskimi cięgnami bez przyczepności.

14

Analysis of steel frame under selected accidental situation

Kukla Damian, Kozłowski Aleksander

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

293--309

EN

The current design codes recommend designing the building structures based on the assumption avoiding the disproportionate to the initial cause damage during accidental situation. As a main strategy to mitigate a progressive collapse an alternative load path method is recommended. Flush and extended bolted end-plate joint to connect beam-to-column were experimentally tested. Hierarchical validation of joint FEM models based on experimental test results were performed. The numerical dynamic analysis by finite element method of selected steel frame under column loss scenario is presented. The planar 2D model of frame were used. Shell elements for beams and columns and solid elements for joints were employed respectively. Nonlinear material and geometry were applied in the analysis. Johnson-Cook model was used to describe the change of steel parameters by dynamic Increase Factor (DIF). The Rayleigh model to include the damping effects in the analysis was used. The dynamic analysis was performed with the use of Abaqus/Explicit module. Main conclusion of presented research it that to achieve the required level of robustness, bolted beam-to-column joints with extended end-plate of thickness more than 15 mm should be used.

PL

Obecne przepisy projektowe zalecają projektowanie i wykonywanie konstrukcji budowlanych w oparciu o unikanie nieproporcjonalnego do pierwotnej przyczyny uszkodzenia w sytuacji wyjątkowej. W obecnych normach projektowych przedstawiono kilka sposobów ochrony konstrukcji przed katastrofą postępującą. Jako główną strategię łagodzenia katastrofy postępującej zaleca się metodę alternatywnej ścieżki obciążenia. Odporność konstrukcji jest definiowana jako zdolność konstrukcji do zatrzymania katastrofy. Wykonano badania doświadczalnie śrubowych węzłów doczołowych belka-słup z blachą wpuszczoną i wystającą. Przeprowadzono walidację hierarchiczną modeli MES węzłów na podstawie wyników badań eksperymentalnych. Przedstawiono dynamiczną analizę numeryczną, opartą na metodzie elementów skończonych, wybranej ramy stalowej w sytuacji wyjątkowej. Zastosowano płaski model konstrukcji. Do budowy modelu ramy wykorzystano odpowiednio elementy powłokowe dla belek i słupów oraz elementy bryłowe dla węzłów. Wykorzystano nieliniowy model materiału i geometrii do wykonania modelu. Charakterystyki materiałowe stali zostały zmodyfikowane przez zastosowanie dynamicznego współczynnika wzrostu (DIF), przy użyciu modelu Johnson-Cook. W obliczeniach wykorzystano moduł Abaqus/Explicit z uwzględnieniem tłumienia. Wyniki analizy wskazują, że zastosowanie w konstrukcji ramowej doczołowych węzłów śrubowych z blachą wystającą o grubości większej niż 15 mm prowadzi do wytworzenia w konstrukcji mechanizmu cięgnowego i zatrzymania katastrofy postępującej.

15

Optimization of the semi-active vibration absorbers

Snitynskyy Volodymyr, Kernytskyy Ivan, Diveyev Bohdan, Horbay Orest, Fornalchyk Yevhen, Humenuyk Ruslan, Sholudko Yaroslav

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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Vol. 30, No. 2

327--336

EN

In this paper, an efficient numerical approach is proposed to maximize the minimal damping of modes in a prescribed frequency range for general viscous tuned-mass systems. Methods of decomposition and numerical synthesis are considered on the basis of the adaptive schemes. The influence of dynamic vibration absorbers and basic design elastic and damping properties is under discussion. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in sinusoidal and impact forced system. One task of this work is to analyze parameters identification of the dynamic vibration absorber and the basic structure. The questions of robustness at optimization of DVA are considered. Different types of control management for semi-active DVA’s are applied. Examples of DVA’s practical implementation are presented.

16

An adaptive RST fuzzy logic and an adaptive PI fuzzy logic controllers of a DFIG in wind energy conversion

Abdallah Abdelkader, Chaker Abdelkader, Allaoui Tayeb

Przegląd Elektrotechniczny

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2021

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R. 97, nr 11

11--20

EN

This paper proposes an adaptive logic controllers for a wind energy conversion system (WECS) based on doubly fed induction generator (DFIG). Active and reactive power flow is controlled simultaneously with a four control methods of the active and reactive currents. These include a direct PI controller, A RST controller, an adaptive fuzzy logic PI (AFLC-PI) and an adaptive RST fuzzy logic with virtual reference (VFLC-RST) controls. The results demonstrate that VFLC-RST are very effective in improving the transient power system stability and very robust against variable transmission line parameters.

PL

W artykule zaproponowano adaptacyjne sterowniki logiczne dla systemu konwersji energii wiatru (WECS) opartego na podwójnie zasilanym generatorze indukcyjnym (DFIG). Przepływ mocy czynnej i biernej jest kontrolowany jednocześnie za pomocą czterech metod regulacji prądów czynnych i biernych. Obejmują one bezpośredni kontroler PI, kontroler RST, adaptacyjną logikę rozmytą PI (AFLC-PI) i adaptacyjną logikę rozmytą RST ze sterowaniem wirtualnym odniesieniem (VFLC-RST). Wyniki pokazują, że VFLC-RST są bardzo skuteczne w poprawianiu przejściowej stabilności systemu zasilania i bardzo odporne na zmienne parametry linii przesyłowej.

17

Modeling damaged precast structural system when its robustness check

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2021

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Nr 3

63--81

EN

Within the framework of traditional approaches to checking for resistance of reinforced concrete buildings and structures to the progressive collapse development, membrane (chain) forces in a damaged structural system are calculated separately, without considering its non-linear bending behavior during the formation of the plastic hinges and without checking the possibility of achieving large deflections. The authors propose an approach to modelling a nonlinear quasi-static reaction of a damaged structural system in an accidental design situation. This approach considers non-linear bending and the resistance of reserved horizontal ties, considering their ultimate ductility. The authors verified the proposed approach based on the results of experimental studies by others researchers. An example of the application of the proposed approach in assessing the robustness of a structural system made of precast concrete with a sudden removal of the central column is considered. In accordance with the provisions of the energy approach, an analysis is made of the contribution of individual resistance mechanisms to the total quasi-static and dynamic resistance of the damaged structural system. We show that the proposed calculation model adequately describes the behavior of a damaged structural system in an accidental design situation, and therefore to carry out parametric studies and check the robustness of building structures.

18

Simplified analytical method for the robustness assessment of precast reinforced concrete structural systems

Tur Viktar, Tur Andrei, Lizahub Aliaksandr

Budownictwo i Architektura

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2021

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Vol. 20, no 4

93--114

EN

The article presents the simplified implementation of alternative load path method based on the energy balance approach. This method should be used to check the global resistance of a damaged structural system after the occurrence of an accidental event. Basic assumptions of simplified analytical models for modelling resistance of horizontal ties in a damaged structural system, taking into account the membrane (chain) effects, were presented. An approach to modelling the dynamic resistance of a damaged structural system based on the energy balance method is described. Calculated dependencies for checking the robustness of a prefabricated multi-storey building with hollow-core slabs after the loss of the central column are proposed and considered using an example. On the considered example, a comparison of the required tie sections area with the dynamic resistance designed using the energy balance method (EBM) and according to the current standards, and a statistical assessment of the reliability of the load-bearing capacity models are carried out. In the end, a brief algorithm for the simplified calculation of the dynamic resistance of a damaged structural system is proposed.

19

Robust trajectory tracking control for autonomous vehicle subject to velocity-varying and uncertain lateral disturbance

Wang Yuqiong, Gao Song, Wang Yuhai, Wang Pengwei, Zhou Yingchao, Xu Yi

Archives of Transport

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2021

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Vol. 57, iss. 1

7--23

EN

Autonomous vehicles are the most advanced intelligent vehicles and will play an important role in reducing traffic accidents, saving energy and reducing emission. Motion control for trajectory tracking is one of the core issues in the field of autonomous vehicle research. According to the characteristics of strong nonlinearity, uncertainty and changing longitudinal velocity for autonomous vehicles at high speed steering condition, the robust trajectory tracking control is studied. Firstly, the vehicle system models are established and the novel target longitudinal velocity planning is carried out. This velocity planning method can not only ensure that the autonomous vehicle operates in a strong nonlinear coupling state in bend, but also easy to be constructed. Then, taking the lateral location deviation minimizing to zero as the lateral control objective, a robust active disturbance rejection control path tracking controller is designed along with an extended state observer which can deal with the varying velocity and uncertain lateral disturbance effectively. Additionally, the feed for ward-feedback control method is adopted to control the total tire torque, which is distributed according to the steering characteristics of the vehicle for additional yaw moment to enhance vehicle handing stability. Finally, the robustness of the proposed controller is evaluated under velocity-varying condition and sudden lateral disturbance. The single-lane change maneuver and double-lane change maneuver under vary longitudinal velocity and different road adhesions are both simulated. The simulation results based on Matlab/Simulink show that the proposed controller can accurately observe the external disturbances and have good performance in trajectory tracking and handing stability. The maximum lateral error reduces by 0.18 meters compared with a vehicle that controlled by a feedback-feedforward path tracking controller in the single-lane change maneuver. The lateral deviation is still very small even in the double lane change case of abrupt curvature. It should be noted that our proposed control algorithm is simple and robust, thus provide great potential for engineering application.

20

Maximum simulated likelihood: don't stop believin'?

Schrey Christopher

Annals of Computer Science and Information Systems

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2021

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Vol. 26

175--180

EN

Unobserved heterogeneity may complicate model estimation in econometrics. To integrate out the effect of unobserved heterogeneity via maximum simulated likelihood (MSL) estimation, assumptions regarding the underlying distribution need to be made. Researchers seldomly discuss these assumptions. This raises the question, to what extent estimation results in the MSL-context are robust to potential distributional mismatch. This work-in-progress derives the research question from the literature. A simulation study is conducted that underpins the relevance of this matter, where results imply that mismatch may introduce significant bias. Intended future work to properly address and answer this question is defined and discussed.