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1

Shape and packing effects in particulate composites: micromechanical modelling and numerical verification

Majewski Michał, Wichrowski Michał, Hołobut Paweł, Kowalczyk-Gajewska Katarzyna

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e86, 1--22

EN

The aim of this study is to analyse the joint effect of reinforcement shape and packing on the effective behaviour of particulate composites. The proposed semi-analytical modelling method combines the Replacement Mori-Tanaka scheme, by means of which the concentration tensors for non-ellipsoidal inhomogeneities are found numerically, and the analytical morphologically representative pattern approac to account for particle packing. Five shapes of inhomogeneities are selected for the analysis: a sphere, a prolate ellipsoid, a sphere with cavities, an oblate spheroid with a cavity as well as an in homogeneity created by three prolate spheroids crossing at right angles. Semi-analytical estimates are compared with the results of numerical simulations performed using the finite element method and with the outcomes of classical mean-field models based on the Eshelby solution, e.g. the Mori–Tanaka model or the self-consistent scheme.

2

Modeling and Performance Evaluation of an Electromagnetic Voltage Regulator via Series Compensation

Brito Vinícius Henrique Farias, Oliveira José Carlos de, Santilio Fabricio Parra

Transactions on Environment and Electrical Engineering

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2020

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Vol. 4, No. 1

12--17

EN

Although there currently exists a wide range of voltage regulators that are commercially available, the search for devices with a simpler physical design remains the focus of research studies. Following this line, an electromagnetic voltage regulator (EVR) arrangement has been proposed. The EVR is constituted of an autotransformer that supplies, via discrete taps, a series transformer that injects voltage for regulating the feeder voltage. Even though its operating principle is shown as being similar to that of other devices on the market, the physical arrangement and operating strategy of EVR show novelties which result in properties such as: economic attractiveness, constructive simplicity, and operational reliability. Moreover, when installing voltage regulators, efficacy studies must be carried out to optimize equipment design. In this context, this paper aims at evaluating the factors that influence the effectiveness of the EVR in restoring voltage variations according to the determinations imposed by regulatory agencies. The ultimate goal of this study is to determine the voltage deviation range that the EVR is able to restore. To achieve this goal, a mathematical modeling of the EVR is given and study cases are computationally carried out to investigate its performance when connected to a typical distribution feeder.

3

Zastosowanie autorskich modeli komputerowych w zagadnieniu bezpieczeństwa ruchu drogowego : kolizja cysterny z chlorem

Brzozowska L.

Logistyka

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2015

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nr 3

602--609, CD 1

PL

W artykule przedstawiono zastosowanie autorskich programów komputerowych służących do modelowania rozprzestrzeniania się zanieczyszczeń w skali miasta. Stosowane programy oparte są o diagnostyczny model pola prędkości powietrza i lagrangeowski model cząstek. W obu modelach zastosowano autorskie elementy modelowania matematycznego. Modele te były poddawane walidacji i weryfikacji [2, 3]. Dodatkowo w preprocesingu stosowany był program GIS Idrisi Andes. Omówiono budowę własnego programu komputerowego oraz etapy modelowania zagadnienia propagacji związków niebezpiecznych. Przedstawiono wyniki obliczeń oraz analizę rozprzestrzeniania się zanieczyszczeń w przypadku wypadku drogowego z udziałem cysterny przewożącej chlor, któremu towarzyszy wyciek substancji do powietrza. Symulowano wystąpienie zdarzenia na terenie miasta Bielsko-Biała, na obwodnicy w obszarze zabudowanym. Założono, że w wyniku kolizji do atmosfery wycieka 10 t chloru. Przeprowadzone symulacje komputerowe pozwalają stwierdzić, że całkowity obszar objęty chmurą zanieczyszczeń o stężeniach ponad dopuszczalnych może zajmować ponad 2,5 km2, a liczba zagrożonych osób sięga 5 000.

EN

In the paper the problems of the emergence of the risks failure, resulting in the accident with tanker and emission of chlorine to the environment, as well as the treatment and use of own computer programs for the diagnosis or prognosis of the consequences of accident were presented. The construction of the program and the stages of modeling and simulation of pollutant dispersion, and example of the application to the analysis of the dispersion of chlorine into the atmosphere in case of a sudden road accident were analyzed. The program, was based on a proprietary implementation of the diagnostic model of the velocity wind field and the Lagrangian particle model. Additionally, the analyzed instances were placed in pre and postprocessing flow using Geographic Information System GIS. Results of calculations and analysis of the propagation of pollutants were described in the case of road traffic accidents with the participation of the tanker lorry transporting chlorine, for which the oytflow substance to air. An appearance of the event was being simulated in the town Bielsko-Biala, on the ring road in the built-up area. Was assumed that as a result of the collision to the atmosphere 10 t of chlorine was leaking out. Computer simulations allows to conclude, that total embraced area with cloud of pollutants about concentrations above the limit can occupy more than 2.5km2, and the number of the endangered people reaches 5 000.

4

Predicting word order universals

Merlo P.

Journal of Language Modelling

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2015

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Vol. 3, No. 2

317--344

EN

This paper shows a computational learning paradigm to compare and test theories about language universals. Its main contribution lies in the illustration of the encoding and comparison of theories about typological universals to measure the generalisation ability of these theories. In so doing, this method uncovers hidden dependencies between theoretical dimensions and primitives that were considered independent and independently motivated.

5

Wpływ oparów metalicznych na spawanie łukowe, część 3: Modelowanie łuku spawalniczego – wyniki. Dymy spawalnicze

Murphy A.

Przegląd Spawalnictwa

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2012

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R. 84, nr 11

12-21

PL

W tej części artykułu przedstawiono wyniki oraz przewidywania obliczeniowego modelowania łuków spawalniczych, a także wpływ oparów metalicznych na parametry łuku. Omówiono powstawanie pyłów wpływających na zdrowie spawacza. Podsumowanie artykułu może być przydatne do tworzenia oprogramowania procesora źródła do sterowania stabilnością łuku, funkcjami ułatwiającymi spawanie i korekty błędów spawacza (reklamowanych w Australii jako oprogramowanie urządzeń, myślących za spawacza).

EN

The results and predictions of computational modeling of welding arcs and influence of metal vapour on arc parameters are presented in this part. The production of welding fume affecting the health of welder also is discussed. A summary of the article can be useful for developing software for intelligent processor control welding arc stability, weld assist functions and correction of errors welder advertised in Australia as a software welders who think for a welder.

6

Self-organized Patterning by Diffusible Factors : Roles of a Community Effect

Batmanov K., Kuttler C., Lhoussaine C., Saka Y.

Fundamenta Informaticae

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2012

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Vol. 118, nr 4

419-461

EN

For decades, scientists have sought to elucidate self-organized patterning during development of higher organisms. It has been shown that cell interaction plays a key role in this process. One example is the community effect, an interaction among undifferentiated cells. The community effect allows cell population to forge a common identity, that is, coordinated and sustained tissue-specific gene expression. The community effect was originally observed in muscle differentiation in Xenopus embryos, and is now thought to be a widespread phenomenon. From a modelling point of view, the community effect is the existence of a threshold size of cell populations, above which the probability of tissue-specific gene expression for a sustained period increases significantly. Below this threshold size, the cell population fails to maintain tissue-specific gene expression after the initial induction. In this work, we examine the dynamics of a community effect in space and investigate its roles in two other processes of self-organized patterning by diffusible factors: Turing’s reaction-diffusion system and embryonic induction by morphogens. Our major results are the following. First, we show that, starting from a one-dimensional space model with the simplest possible feedback loop, a community effect spreads in an unlimited manner in space. Second, this unrestricted expansion of a community effect can be avoided by additional negative feedback. In Turing’s reaction-diffusion system with a built-in community effect, if induction is localized, sustained activation also remains localized. Third, when a simple cross-repression gene circuitry is combined with a community effect loop, the system self-organizes. A gene expression pattern with a well-demarcated boundary appears in response to a transient morphogen gradient. Surprisingly, even when the morphogen distribution eventually becomes uniform, the system can maintain the pattern. The regulatory network thus confers memory of morphogen dynamics.

7

The simulation of performance characteristics of port injection dedicated compressed natural gas spark ignition engine

Semin, Abu Bakar R., Ismail A.

Journal of KONES

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2008

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Vol. 15, No. 2

427-432

EN

This paper presents the computational modelling simulation results of port/sequential injection dedicated compressed natural gas (CNG) spark ignition engine to investigate and evaluate the engine performance while base engine converted by using compressed natural gas as an alternative fuel. The baseline engine in this research is four stroke direct injection diesel engine. The computational modelling design and development has performed using GT-Power software at Automotive Excellent Centre Laboratory, Faculty of Mechanical Engineering, University Malaysia Pahang, Malaysia. To investigate the engine performance, the engine computational model is operated between 500-4000 rpm, under steady state condition. In this research, the sequential injection dedicated compressed natural gas spark ignition engine performance investigation results such as torque, power, fuel consumption pressure and exhaust gas emissions were investigated and compared to base diesel engine performance. From the CNG engine computational modelling simulation results are shown that by development of sequential injection dedicated compressed natural gas spark ignition engine has a potential to reduce the engine emissions. Unfortunately, the development of sequential injection dedicated compressed natural gas spark ignition engine can be reducing the engine performance. However, the study of required to improve the performance of sequential injection dedicated compressed natural gas spark ignition engine has a potential of reducing engine.

8

Numerical modelling of blast waves generated by explosion of an elongated gaseous cloud

Kuczaj A.

Journal of Technical Physics

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2002

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Vol. 43, no 1

43-60

EN

A numerical solution is given for the 2D problem of the detonation products scattering of exploding cylindrical gaseous cloud. Numerical simulations have been performed for unconfmed gaseous explosions for various proportions of the longitudinal-to-transverse dimensions of the cloud. The near field of air blast is highly asymmetrical and directional, thus simple engineering approximations of the blast parameters have been given for various directions of blast wave propagation.

9

Numeryczne modelowanie fali podmuchowej generowanej wybuchem wydłużonego obłoku gazowego

Kuczaj A.

Biuletyn Wojskowej Akademii Technicznej

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2001

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Vol. 50, nr 7

103-125

PL

W pracy rozwiązano w sposób numeryczny dwuwymiarowe zagadnienie rozlotu produktów detonacji walcowego obłoku gazowego. Przeprowadzono symulację dla wybuchów obłoków gazowych o różnych stosunkach wymiaru poprzecznego do podłużnego. Uwzględniając asymetryczne i ukierunkowane pole ciśnienia wokół detonującego obłoku, podano proste wzory inżynierskie szacujące wartości parametrów fali podmuchowej na różnych kierunkach jej propagacji.

EN

A numerical solution is given for the 2D problem of scattering of detonation products from cylindrical gaseous cloud. Numerical simulations have been performed for unconfined gaseous explosions compared with different value of longitudinal and transverse length. The near field of air blast is highly asymmetrical and directional, thus simple engineering descriptions of blast parameters have given for various directions of propagation of the blast wave.

10

Strain state and strength of acetabular component of total hip-joint endoprosthesis.

Jira J., Jirova J., Micka M.

Acta of Bioengineering and Biomechanics

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1999

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Vol. 1, nr 2

79-83

EN

The paper deals with the new cementless acetabular cup of the Beznoska type. This cup is made of 1 mm thick titanium covering and polyethylene inner layer. Good initil implant stability is ensured by titanium projections on the outer surface. The purpose of the experimental research was to measure strains at selected points on the outer surface of the artificial cup. A computation model enables us to analyse the strain state generated not only by concentrated load, but also by uniformly distributed load or by varing load. The aim of the research was to analyse the strain state of the acetabular component and to find out the limit loading for assesment of strength and the loss of stability of the cup structure.