Wyniki wyszukiwania - Biblioteka Nauki

1

Axial dispersion models and their basic properties

100%

Bartova D. , Jakes B. , Kukal J.

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2009

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tom Vol. 19, no. 1

5-22

EN

The paper is oriented to summary of important basic relations, which characterize behavior of four axial dispersion models (AEO: axial enforced closed-open model, ACO: axial closed-open model, ACC: axial closed-closed model, AOO: axial open-open model) and three referential models (ideal mixed model, plug flow model, cascade of ideal mixers without back-mixing). Selected basic properties (parametric characteristics) of these models can be used for parameter identification of included hydrodynamic flow structure models. Mathematical description of models including initial and boundary conditions, transfer function, model transient response to Dirac impulse as weighting (impulse) function, model transient response to step function as step response are included in this study. There are also included further characteristics of impulse function: raw moments up to 4th order, variance, variation coefficient, skewness , kurtosis, location and value of mode. Complete set of these characteristics for all studied models is collected (model-by-model) in seven tables. The authors declare several properties of weighting function as key ones: value of 1st raw (dimensional) moment, parametric values and mode properties, related to dependence on Peclet number. The plots of parametric values and mode properties vs. Peclet number are mentioned in the paper for four studied axial dispersion models.

2

Dynamic modeling and parametric analysis of differential gearbox used in electric vehicle

86%

Ullah N. , Song C. , Zhu C. , Ou Z. , Tan C.

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tom Vol. 58 nr 1

73--85

EN

The aim of this study is to perform the modeling and parametric analysis of dynamic mesh force in the light of resonance modes. Firstly, dynamic modeling of a differential gearbox has been performed by using the lumped parameter method. Then, the resonant points from Campbell diagrams were studied for the first three critical harmonic orders. Furthermore, two case studies were proposed in order to investigate the impact of radial clearance and face width on the dynamic mesh force along with resonance. Simultaneously, resonance identification and elimination were studied for two working conditions. Results show that the influence of lowering face width of pinions is more effective on mesh force reduction and resonance elimination as opposed to the first case study by enhancing wheel side mesh stiffness.

3

Analysis of the Influencing Factors of the Acoustic Performance of the Muffler Considering Acoustic-structural Coupling

86%

Zhao B. , Li H.

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tom Vol. 47, No. 4

479--490

EN

In the calculation of the acoustic performance of mufflers, the walls of mufflers are usually treated rigidly without considering the acoustic-structural coupling, but the results so calculated differ significantly from the actual situation. Based on the basic equations, the article derives the finite element equations of the muffler system while considering the acoustic-structural coupling effect and theoretically analyses the connection between the acoustic-structural coupling system and the structural and acoustic modes. The structural and acoustic modes of the muffler are calculated and the reasons for the mutation of the transmission loss curve of the muffler when the acoustic-structural coupling is considered are analysed. The results show that the acoustic-structural coupling is the result of the interaction between the structure and the air inside the expansion chamber under acoustic excitation, which manifests mutations in the sound pressure inside the muffler in some frequency bands. Then, using a single-chamber muffler as an example, the transmission loss is used to characterise the performance of the muffler. The effects of different factors such as shell thickness, structure, porous media material lining, and restraint method on the acoustic-structural coupling effect of the muffler are analysed, and the structure of a double-chamber muffler is successfully optimised according to the conclusions.

4

In and Out, or the Memoir’s Many Points of View

72%

Kusek R.

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nr 8(11) cz.1

99-112

EN

The aim of this paper is to investigate the concept of the point of view with regard to the genre of memoir. Having provided a brief discussion of the genre’s poetics and various, often conflicting attempts at establishing its generic indexes as well as its generic identity, the paper will examine several contemporary specimens of the memoir and will try to identify the occurrence of Gérard Genette’s modal triad (i.e. internal focalization, external focalization, and zero focalization) in their respective narratives. What is more, the paper will attempt to conclude whether such a narratological category as “mode” can be considered a generative tool as far as the memoir’s genology is concerned and, if so, what overall implications this recognition might have for understanding the memoir’s poetics and its traditional understanding as a genre of non-fiction.

5

Quantifiable measures of the structural degradation of construction materials

72%

Kaźmierczak H. , Pawłowski T. , Wojniłowicz Ł.

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tom Vol. 14, No. 4

77--83

EN

The authors have outlined a method for analysing the fatigue degradation of mechanical structures described in terms of variations in the mobility of dynamic impedances, their real and imaginary parts and fluctuations in the strength of dynamic rigidity and the strength of the internal damping of structures expressed as a function of degradation time (the number of degrading impulse impacts). The variations are identified over the full scope of destruction ranging from nucleation to dominant fracturing. Such an identification is carried out by the method of experimental modal analysis and by energy-based methods with the use of a mechatronic accelerated testing station. The paper provides definitions of the related measurable measures of the process[6]. The point is illustrated with an overview of selected strength characteristics of modern construction steel.

PL

Przedstawiono zarys metody analizy procesu degradacji zmęczeniowej struktur mechanicznych, opisanej przez charakterystyki zmian mobilności dynamicznych, impedancji, ich części rzeczywistych i części urojonych oraz zmian mocy sił sztywności dynamicznych i mocy sił tłumienia wewnętrznego struktur w funkcji czasu procesu degradacji(liczba degradujących uderzeń impulsowych). Charakterystyki te wyznacza się w pełnym zakresie procesu niszczenia od nukleacji do dominującego pęknięcia metodą eksperymentalnej analizy modalnej i metodami energetycznymi z zastosowaniem mechatronicznego stanowiska badań przyspieszonych. Praca zawiera definicje mierzalnych miar procesu. Jako przykład zamieszczono wybrane charakterystyki właściwości wytrzymałościowych nowoczesnych stali konstrukcyjnych.

6

On how to Speak about Universals and Particulars in the Jaina Philosophical Literature of the Classical Period (5th–10th c. CE)

72%

Glinicka M.

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nr 2

7

Складні сполучникові речення з асиметрією форми й змісту як периферія синтаксичної підсистеми сучасної української мови

58%

Polozova O.

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nr 12(17)

4.7-4.13

UK

У статті окреслено типові прояви кількісної та якісної асиметрії форми та змісту на рівні складних сполучникових конструкцій сучасної української мови. Проаналізований матеріал переконує в поширеності формально-змістової невідповідності в синтаксисі складно сполучникового речення й доводить потребу в цілісному й усебічному досліджені цього феномену на синтаксичному рівні системи української мови в цілому.

EN

The article outlines the typical symptoms of quantitative and qualitative asymmetry of the form and content at the level of complex conjunctive structures of the modern Ukrainian language. The analyzed material proves the prevalence of formal semantic inconsistencies in the syntax of a complex conjunctive sentence and proves the need for holistic and comprehensive studies of this phenomenon on the syntactic level of the Ukrainian language system as a whole.

8

Construction schedule of works as combinatorial optimization problem

51%

Dytczak M. , Ginda G.

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2014

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tom R. 111, z. 2-B

283--289

EN

Construction schedule optimization generally deals with the identification of the feasible sequence of activities and allocation of modes that provide the most efficient construction performance according to the assumed evaluation criteria. The specific technological order of activities results in the numerous feasible sequences of activities and availability of alternative modes results in the numerous mode combinations. Construction scheduling becomes, therefore, a difficult combinatorial problem that is usually underestimated by the planners. This is the main reason for obtaining schedules that result in construction implementation lasting too long and costing too much. It is, nevertheless, possible to identify the construction schedules that provide excellent results. A simple, simulationbased approach is presented in this paper. Its originality results from nature of applied model and a way the calculations are made. The effectiveness of the approach is illustrated by means of a sample analysis based on data provided by [1]. The approach also proved useful for solving scheduling problems in engineering practice.

PL

Optymalizacja harmonogramu przedsięwzięcia polega na doborze takiej dopuszczalnej kolejności wykonywania prac oraz przydzieleniu takich sposobów wykonania operacjom, które zapewnią najlepsze możliwe, zgodnie z przyjętymi kryteriami oceny harmonogramu, wykonanie przedsięwzięcia. Z technologicznego porządku prac wynika zwykle duża, a często nawet astronomiczna liczba ich dopuszczalnych uporządkowań. Złożoność procesu harmonogramowania dodatkowo podwyższa dostępność alternatywnych sposobów wykonania prac. Harmonogramowanie przedsięwzięć stanowi więc w istocie trudne, a przy tym niedoceniane przez planistów, zagadnienie kombinatoryczne. W rezultacie otrzymujemy harmonogramy odpowiadające nadmiernie czaso- i kosztochłonnej realizacji przedsięwzięcia. Przy odrobinie wysiłku można jednak uzyskać harmonogramy, które odpowiadają krótkiej i taniej realizacji przedsięwzięcia. Temu celowi służy również autorskie narzędzie symulacyjne przedstawione w pracy. Stanowi ono oryginalne podejście zarówno w zakresie modelu, jak i sposobu wykonywania obliczeń, do których dane zaczerpnięto z pracy [1]. Wyniki pracy zostały także zastosowane w praktyce inżynierskiej.