Wyniki wyszukiwania - BazTech

1

Design analysis of an innovative concept of a displacement motor yacht with eco-drive

Bortnowska Monika, Kapała Dawid

Zeszyty Naukowe Politechniki Morskiej w Szczecinie

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2024

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nr 77 (149)

29--37

EN

In response to the challenges of environmental protection and the need to be close to nature and to reconnect with it, an unusual motor yacht design is developed with an abstract architectural form modeled on an armadillo. Due to the innovative form of the hull, a specific approach to pre-design is used, with the research objective of verifying that for the organic form of the hull, it would be possible to meet all the design criteria and regulations required for the design of a yacht. This article first characterizes the initial assumptions and then presents the process of determining the main dimensions with simultaneous modification of the hull shape. In order to maintain the basic dimensional proportions, based on the classic motor yacht, the recommended values of design factors are controlled. Moreover, the hydrostatic parameters of the unconventional hull shape are calculated. As a result of preliminary resistance and propulsion analyses, a propulsion system in the form of electric motors is selected, and, to meet emission requirements, the use of photovoltaic panels is additionally proposed. A stability and equilibrium analysis is carried out for one of the load cases and checked with the requirements of the Polish Register of Shipping (PRS) rules. The design of the hull of the yacht, covered in an interesting form of scales, together with the layout of the yacht’s interior, is presented in three-dimensional form, bringing the conceptual idea to life. The result of the design work and analysis is an inspiring hull shape based on nature, complying with the design guidelines and regulations that apply to yacht design.

2

A comparative study of grid-following and grid-forming control schemes in power electronic-based power systems

Gao Xiao, Zhou Dao, Anvari-Moghaddam Amjad, Blaabjerg Frede

Power Electronics and Drives

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2023

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Vol. 8 (43)

1--20

EN

Along with de-carbonisation, the penetration of power electronic converters has increased, and the power system has become a power electronic-based power system. In such a situation, the stability of the power system faces great challenges. In the event of a large disturbance, the power grid will lack the ability to maintain a stable voltage and frequency. In order to improve the stability of the power grid, the traditional grid-following (GFL) control is needed to be converted to the grid-forming (GFM) control. This paper analyses the control schemes of the GFL and GFM converters by investigating their state-space models, and the eigenvalue trajectories of both control schemes are shown to analyse the stability of the systems. Moreover, a case study is exemplified to compare the performance of the two control strategies while responding to frequency disturbances. Finally, a time-domain simulation model of a 15 kW grid-connected converter is built in Matlab/Simulink to benchmark the performance of the GFL and GFM converters under different working conditions. The result reveals that the GFL converter may encounter some instabilities when applied in power electronic-based systems, while the GFM converter is more suitable for the weak power grid.

3

Existence, uniqueness and parameter perturbation analysis results of a fractional integro-differential boundary problem

Zhang Nan, Zhang Lingling, Ngungu Mercy, Adeniji Adejimi, Addai Emmanuel

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 4

art. no. e145938

EN

In the formulation, the existence, uniqueness and stability of solutions and parameter perturbation analysis to Riemann-Liouville fractional differential equations with integro-differential boundary conditions are discussed by the properties of Green’s function and cone theory. First, some theorems have been established from standard fixed point theorems in a proper Banach space to guarantee the existence and uniqueness of positive solution. Moreover, we discuss the Hyers-Ulam stability and parameter perturbation analysis, which examines the stability of solutions in the presence of small changes in the equation main parameters, that is, the derivative order η, the integral order β of the boundary condition, the boundary parameter ξ , and the boundary value τ. As an application, we present a concrete example to demonstrate the accuracy and usefulness of the proposed work. By using numerical simulation, we obtain the figure of unique solution and change trend figure of the unique solution with small disturbances to occur in different kinds of parameters.

4

An observer design for Takagi-Sugeno fuzzy bilinear control systems

Delmotte François, Hadj Taieb Nizar, Hammami Mohamed Ali, Meghnafi Houria

Archives of Control Sciences

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2023

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Vol. 33, No. 3

631--649

EN

In this paper, the observer design problem for a T-S fuzzy bilinear control system is investigated. First, an observer of Kalman type is designed to estimate the system states for the linear case. Then, some new sufficient conditions are derived to show the exponential convergence of the solutions of the error equation for fuzzy bilinear systems. Furthermore, we consider some uncertainties of the system that are bounded and satisfy a certain condition where an observer is designed. Moreover, an application to Van de Vusse system is given.

5

A study of landslide body control of black bovine cave copper ore mining and beneficiation project

Wu Hanhui

Archives of Civil Engineering

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2023

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Vol. 69, nr 2

291--309

EN

Landslide is a common geological disaster which causes huge losses to people’s properties and national economic development. How to prevent and control landslides has become an important issue. This article introduces the geological and geographical environment of the landslide body, analyzes the basic characteristics of the landslide, calculates the landslide stability based on the ultimate equilibrium theory-based transfer coefficient method, discusses the development trend of the landslide and comes up with corresponding control schemes by taking the landslide body of Black Bovine Cave Copper Ore Mining & Beneficiation Project as example. It is found that the control scheme - “anti-slide pile + retraining wall + baffle + anchor cable” can be used to effectively prevent and control the geological disaster according to calculation. The study results can provide a reference for landslide body control.

6

Sensitivity and stability analysis for groundwater numerical modeling: a field study of finite element application in the arid region

Jafarzadeh Ahmad, Pourreza-Bilondi Mohsen, Akbarpour Abolfazl, Khashei-Siuki Abbas, Azizi Mohsen

Acta Geophysica

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2023

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Vol. 71, no. 2

1045--1062

EN

This study intends to investigate the impacts of scheme type, time step, and error threshold on the stability of numerical simulation in the groundwater modeling. Hence, a two-dimensional finite element (FE) was implemented to simulate groundwater flow in a synthetic test case and a real-world study (Birjand aquifer). To verify the proposed model in both cases, the obtained results were compared with analytical solutions and observed values. The stability of numerical results was analyzed through different schemes and time-step sizes. Besides, the effect of the error threshold was examined by considering different threshold values. The results confirmed that the FE model has a good capacity to simulate groundwater fluctuations even for the real problem with more complexities. Examination of implicit outputs indicated that groundwater simulations based on this scheme have good accuracy, stability, and proper convergence in all time intervals. However, in the explicit and Crank–Nicolson schemes the time interval should be less than or equal to 0.001 and 0.1 day, respectively. Also, results reveal that for making stability in all schemes the value of the error threshold should not be more than 0.0001 m. Moreover, it derived that the boundary conditions of the aquifer influence the stability of numerical outputs. Finally, it was comprehended that as time interval and error threshold increases, the oscillation rate propagated.

7

Stability of GPS and GLONASS onboard clocks on a monthly basis

Ziętala Michał

Zeszyty Naukowe. Transport / Politechnika Śląska

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2022

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z. 114

193--209

EN

This paper presents the stability of the GPS and GLONASS system clocks’ stability. It describes the construction of these two systems and calculated four different Allan variances (AVAR), based on the MGEX (the Multi-GNSS Experiment) clock products. Four used variances allowed making a better analysis of each GNSS system clock. The results are shown at different averaging times from 5 s as successive multiples to 655,360 s in a monthly period. The stability of GPS and GLONASS clocks is included in the range of 10-12~10-14 s. The results showed that GLONASS clocks are stable (10-12~10-14 s) and are affected with white frequency noise (WFM). The GPS clock stability models have more fluctuations for τ > 40,960 s and the mean stability is concluded between 10-12~10-13 s. Mean frequency accuracy for GPS clocks is related with WFM and Random Walk Frequency (RWF). The differences in clock stability are caused by several factors – block type, type of clock and the time of a satellite in orbit. These factors have an influence on stability results.

8

A robust voltage H∞ controller in dg-connected inverter based on auto-calibration of adjustable fractional weights

Amieur Oualid, Zidani Fatiha

Przegląd Elektrotechniczny

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2022

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R. 98, nr 2

21--27

EN

In this paper a H∞ control technique addresses the voltage regulation in distributed generation (DG) system connected to power converter under harmonic disturbances. The DG control technique combines a discrete sliding mode control (DSMC) in the current control and a Robust Servomechanism Problem (RSP) in the voltage control. Besides, a fractional Order Proportional-Integral-Derivative (FOPID) controller synthesized with an automatic calibration of adjustable fractional weights is formulated in this work. For performance and high robustness requirements, the parameters of FOPID are optimized through solving a multiobjective optimization problematic based on the automatic calibration of the weighted-mixed sensitivity problem. Furthermore, for ensuring an adequate calibration of parameters, the Integral of Time Weighted Absolute Error (ITAE) criterion with Genetic Algorithm (GA) are used to achieve better voltage regulation. The simulation results show that it can achieve trade-off between nominal performance (NP) and robust stability (RS) margins for the constrained uncertain plants in the large range frequencies. Also, the results validate the effectiveness of the proposed control at which both low total harmonic distortion (THD) and low tracking error.

PL

W niniejszym artykule technika sterowania H∞ dotyczy regulacji napięcia w systemie generacji rozproszonej (DG) podłączonym do przekształtnika mocy w warunkach zakłóceń harmonicznych. Technika sterowania łączy dyskretne sterowanie w trybie ślizgowym (DSMC) w sterowaniu prądem i solidny problem z serwomechanizmem (RSP) w sterowaniu napięciem. Poza tym, w niniejszej pracy sformułowano regulator ułamkowo całkująco-różniczkujący (FOPID) zsyntetyzowany z automatyczną kalibracją regulowanych mas ułamkowych. Parametry FOPID są optymalizowane poprzez rozwiązanie problemu optymalizacji wielokryterialnej opartej na autokalibracji problemu wraźliwości mieszanej ważonej dla wymagań dotyczących odporności między nominalną wydajnością (NP), solidną stabilnością (RS) marżami i kompromisem między nimi w dużych zakres częstotliwości. Wyniki symulacji potwierdzają skuteczność proponowanego sterowania, przy którym zarówno wysoka odporność, jak i niskie całkowite zniekształcenia harmoniczne (THD).

9

Slope reinforcement design based on GeoStudio and FLAC3D

Yu Rongxia, Huang Zhian, Yang Zhiquan

Mining Science

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2022

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Vol. 29

141--163

EN

Slope stability of open pit mines has been a hot issue of economic and safety concern. In order to reduce the accidental casualties caused by slope instability, targeted reinforcement solutions should be proposed for them. In this paper, GeoStudio and FLAC3D software were used to model the slope an open pit mine. The safety factors of the slope under natural, rainfall and seismic conditions are analyzed in turn. Additionally, the safety factors derived from different algorithms are compared to mutually verify the reliability of the slope stability analysis. Two sets of reinforcement design solutions – anchor rod and anti-slip pile – are proposed. Then, the two solutions are optimized so that the safety factors of the slope under three conditions reach 1.3, 1.2 and 1.1, respectively, and the optimal solution is selected from the two solutions by combining the economic benefits. The results show that the optimized anchor and anti-slide pile reinforcement solutions result in the safety factors of the slope under different conditions, reaching 1.441, 1.258, and 1.324 and 1.4, 1.238, and 1.23, respectively. The anti-slide pile reinforcement solution is more economical than the anchor reinforcement solution, so it is recommended that the anti-slide pile reinforcement solution should be chosen as the final solution.

10

Mathematical modeling and analysis of mycobacterium tuberculosis transmission in humans with hospitalization and reinfection

Mustapha Umar T., Idris Buhari, Musa Salihu S., Yusuf Abdullahi

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 1

55--66

EN

Tuberculosis (TB), a serious public health infection that mainly affects the lungs, is caused by bacteria (Mycobacterium tuberculosis, TB). This research is designed and analyzed using a compartmental modelling approach to study the transmission dynamics of TB with different stages of infection. Qualitative analysis of the proposed model reveals that the model exhibits two equilibrium points: the disease-free equilibrium point (DFE) and the endemic equilibrium (EE). The basic reproduction number (R0 ) is determined using the next generation matrix technique, and stability analysis is carried out to show whether the disease can persist or die out in population. Further analysis of the model shows that the EE is globally asymptotically stable (GAS) when R0 > 1. With the aid of the forward sensitivity index method, we determine the most sensitive parameters of the model to control the spread of TB infection effectively. Our analysis shows that treatment (medication) and campaign awareness coupled with other key control measures, could help maintain the spread of MTB infection in human geographical boundaries.

11

Mathematical analysis and numerical simulation of time-fractional host-parasitoid system with Caputo operator

Owolabi Kolade M., Pindza Edson

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 1

79--90

EN

In this paper, a time-fractional host-parasitoid dynamics which is regarded as a new variant of the novel Nicholson-Bailey model is considered in the sense of the Caputo operator. The model equation is examined for linear stability analysis to guide in ensuring the best choice of parameters when simulating the full dynamical system. Furthermore, this work provides a suitable numerical technique for the approximation of the Caputo fractional derivative with order ρ ∈ (0, 1]. To explore the dynamic richness of the model, numerical results are provided for different values of α.

12

Finite difference method for the fractional order pseudo telegraph integro-differential equation

Modanli Mahmut, Ozbag Fatih, Akgül Ali

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 1

41--54

EN

The main goal of this paper is to investigate the numerical solution of the fractional order pseudo telegraph integro-differential equation. We establish the first order finite difference scheme. Then for the stability analysis of the constructed difference scheme, we give theoretical statements and prove them. We also support our theoretical statements by performing numerical experiments for some fractions of order α.

13

Dynamic performance and stability analysis of an active inerter-based suspension with time-delayed acceleration feedback control

Wang Yong, Jin Xian-Yu, Zhang Yun-Shun, Ding Hu, Chen Li-Qun

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 2

art. no. e140687

EN

An active inerter-based suspension with acceleration feedback control is proposed in this paper, the time delay generated in the controllers and actuators is considered, which constitutes the time-delayed active inerter-based (TDA-IB) suspension. The dynamic equation of the TDA-IB suspension is established and is a neutral type of delay differential equation (NDDE) in which the time delay exists in the highestorder derivative. The stability analysis is conducted by calculating the number of unstable characteristic roots based on the definite integral stability method, the stable and unstable regions are determined. The effect of time delay and feedback gain on the dynamic performance of the TDA-IB suspension under harmonic, random, and shock excitations is studied in detail and compared with the parallel-connected inerterbased (PC-IB) and traditional suspensions. The results show that the TDA-IB suspension is asymptotically stable for smaller feedback gain and time delay, through increasing the feedback gain, the stable regions shrink, and a smaller time delay could cause the system to become unstable. Furthermore, the time delay could regulate the resonance peak around the unsprung mass natural frequency and generate multiple high-frequency resonance peaks. If the time delay is chosen appropriately and falls into the stable range, the TDA-IB suspension could improve the dynamic performance for the suspension stroke and dynamic tire load while having a deterioration for the vehicle body acceleration compared with the PC-IB and traditional suspensions.

14

Stability analysis of hybrid Al2O3-TiO2 nano-cutting fluids

Arifuddin A., Redhwan A.A.M., Syafiq A.M., Zainal Ariffin S., Aminullah A.R.M., Azmi W.H.

Archives of Materials Science and Engineering

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2022

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Vol. 117, nr 1

5--12

EN

Purpose: This paper is to study the stability of the current combination of hybrid nano-cutting fluids due to the recent progress in the analysis of nano-cutting fluids, such as the assessment methods for the stability of nano-cutting fluids, have revealed that instability is a common problem associated with nano cutting fluids. Design/methodology/approach: Five samples of 0.001 vol% that are suitable to be tested at UV-Vis machine, Al2O3–TiO2 hybrid nano-cutting fluid was prepared using a one-step process with the help of a magnetic stirrer to stir for 30 minutes with different sonication time to determine the best or optimum sonication time for this hybrid nano-cutting fluid. Stability of nano-cutting fluids was analyses using UV–Vis spectrophotometer (0.001%, 0.0001%, 0.00001%), visual sedimentation (1%, 2%, 3%, 4%), TEM photograph capturing techniques (2%) and zeta potential analysis (0.001%, 0.00001%), that used different volume concentration that is suitable for each type of stability analysis. Findings: The stability analysis reveals that the best sonication time is 90 minutes, and the UV-vis spectrophotometer shows the stability of all samples is above 80% during a month compared to the initial value. Further, visual sedimentation shows good stability with minimum sedimentation and colour separation only. The zeta potential value also shows great stability with a value of 37.6 mV. It is found that the hybrid nano-cutting fluid is stable for more than a month when the nano is suspended in the base fluid of conventional coolant. Research limitations/implications: The result in this paper is based on the experimental study of Al2O3-TiO2/CNC coolant base hybrid nano-cutting fluid for a month. However, to further validate the results presented in this paper, it is recommended to prolong the stability assessment time for six months for longer shelf life. Practical implications: The finding of this experimental study can be useful for high-precision product machining using similar CNC coolants, especially for aircraft and airspace applications for machining parts. Originality/value: No thorough stability assessment using all four types of stability analysis is done on Al2O3-TiO2/CNC Coolant base hybrid nano cutting fluid.

15

The use of the linear form of dynamical equations of the satellite attitude control system for its analysis and synthesis

Moldabekov Meirbek, Sukhenko Anna, Shapovalova Darya, Yelubayev Suleimen

Journal of Theoretical and Applied Mechanics

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2021

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Vol. 59 nr 1

109--120

EN

At present, the methods based on using linearized dynamical equations are applied for syn- thesis of an attitude control system of a satellite with nonlinear dynamics. Linearized equa- tions describe the satellite dynamics approximately, which is the main their disadvantage. This article shows that basing on the angular momentum theorem, the nonlinear dynamical equations of the satellite attitude control system can be represented in the form of linear differential equations with variable coefficients, which makes it possible to use engineering methods of stability analysis and analysis of transient quality in the process of synthesis of the satellite attitude control system.

16

Utrata stateczności osiowo ściskanych słupów dwugałęziowych

Piotrowski Rafał, Siedlecka Monika

Inżynieria i Budownictwo

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2021

|

R. 77, nr 5-6

242--246

PL

Przedstawiono wyniki analitycznych i numerycznych rozważań dotyczących formy lokalnej i globalnej utraty stateczności osiowo ściskanych bisymetrycznych prętów dwugałęziowych połączonych sztywnymi przewiązkami, w jednej lub dwu płaszczyznach, bądź przeponami. Poza oczywistym wpływem sposobu podparcia końców pręta na postać wyboczenia, uwzględniono także rozstaw gałęzi i ilość połączeń między nimi.

EN

The analysis covers the forms of local and global loss of stability of axially compressed bisymmetric two-branch bars connected with rigid lacings, in one or two planes, or with diaphragms. Apart from the obvious influence of the method of supporting the bar ends on the buckling form, the branch spacing and the number of connections between them were also taken into account.

17

Analiza stateczności zapory ziemnej zbiornika Dzierżno Duże w warunkach filtracji nieustalonej

Sternik Krzysztof, Wolfram Eliza

Inżynieria i Budownictwo

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2021

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R. 77, nr 9-10

456--460

PL

Przeprowadzono analizę stateczności korpusu i podłoża zapory ziemnej. Wyznaczono wartości współczynnika stateczności w przypadku trzech wariantów zapory: bez przegrody przeciwfiltracyjnej, z przegrodą umiejscowioną w stopie skarpy odwodnej oraz z przegrodą w koronie zapory przy dwóch różnych poziomach piętrzenia zbiornika. Porównano wyniki obliczeń metodą elementów skończonych z wynikami uzyskanymi metodami równowagi granicznej.

EN

Stability analysis of the embankment dam and its substrate. Determination of the factor of safety for three embankment dam configurations: without an impervious barrier and with a barrier located at the upstream slope and in the crest of the dam. Two different flood surcharges taken into account. Comparison of calculation results by finite element method with results obtained by limit equilibrium methods.

18

Numerical treatment of the generalized time-fractional Huxley-Burgers’ equation and its stability examination

Hadhoud Adel R., Alaal Faisal E. Abd, Abdelaziz Ayman A., Radwan Taha

Demonstratio Mathematica

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2021

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Vol. 54, nr 1

436--451

EN

In this paper, we show how to approximate the solution to the generalized time-fractional Huxley-Burgers’ equation by a numerical method based on the cubic B-spline collocation method and the mean value theorem for integrals. We use the mean value theorem for integrals to replace the time-fractional derivative with a suitable approximation. The approximate solution is constructed by the cubic B-spline. The stability of the proposed method is discussed by applying the von Neumann technique. The proposed method is shown to be conditionally stable. Several numerical examples are introduced to show the efficiency and accuracy of the method.

19

Stability and robustness analysis of discrete-time fractional-piecewise-constant-order PID controller

Oziablo Piotr, Mozyrska Dorota, Wyrwas Malgorzata

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e137937

EN

In the paper we propose a fractional-piecewise-constant-order PID controller and discuss the stability and robustness of a closed loop system. In stability analysis we use the transform method and include the Nyquist-like criteria. Simulations for designed controllers are performed for the second-order plant with a delay.

20

Research on stability and sensitivity of the rotating machines with overhung rotors to lateral vibrations

Szolc Tomasz, Konowrocki Robert

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e137987

EN

The rotating machines with overhung rotors form a broad class of devices used in many types of industry. For this kind of rotor machine in the paper, there is investigated an inf luence of dynamic and static unbalance of a rotor, parallel and angular misalignments of shafts, and inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed through a hybrid structural model of the machine rotor-shaft system, consisting of continuous beam finite elements and discrete oscillators. Numerical calculations are carried out for parameters characterizing a heavy blower applied in the mining industry. The main goal of the research is to assess the sensitivity of the imperfections mentioned above on excitation severity of rotor-shaft lateral vibrations and motion stability of the machine in question.