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1

Stabilization of a 1-D transmission problem for the Rayleigh beam and string with localized frictional damping

Hong Gimyong, Hong Hakho

Journal of Applied Analysis

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2023

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Vol. 29, nr 1

77--90

EN

We are concerned with the stability of a 1-D coupled Rayleigh beam-string transmission system.We obtain the polynomial decay rate t−1 or the exponential decay rate for the given transmission system whether the frictional damping is only effective in the beam part or the string part, respectively. This paper generalizes the recent result in [Y.-F. Li, Z.-J. Han and G.-Q. Xu, Explicit decay rate for coupled string-beam system with localized frictional damping, Appl. Math. Lett. 78 (2018), 51-58]. The main ingredient of the proof is some careful analysis for the Rayleigh beam and string transmission system.

2

Model of a Drive System for Low-Floor Trams with a Four-Linkage Coupling

Sanecki Henryk, Czauderna Tomasz

Problemy Kolejnictwa

|

2022

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Z. 196

137--149

EN

The article describes the structure and principles of operation of a drive system used in some low-fl oor trams. The system consists of electric motors, gear transmissions as well as hollow shaft s and four-linkage couplings causing the wheels to move. During the study, a dynamic model was built and the parameters needed to carry out a simulation were determined. NGT6 low-floor tram wagons operated by MPK S.A. Cracow were used as examples of existing vehicles. Due to the lack of available data, part of the work was devoted to determining mass moments of inertia of drive system components using an experimental method of torsional vibrations of a string. In subsequent chapters, a mathematical model was developed and a tram start-up simulation was performed based on specific parameters of the individual system components. Some of the results were presented in the form of graphs.

3

Multimodalne pomiary drgań struny

Stefaniak Marta, Nosorowski Witold

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

|

2019

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Nr 68

53--56

PL

W artykule zostały przedstawione badania drgań struny zrealizowane przy użyciu szybkich kamer wizyjnych, mikrofonu oraz akcelerometru. Obiektem badań były instrumenty muzyczne. Opisano zjawiska zachodzące w instrumencie podczas tworzenia się i wydobywania z niego dźwięku. Celem pracy było zbadanie różnic w wynikach otrzymanych poprzez pomiary wykonane z użyciem zróżnicowanych reprezentacji obrazowych i sygnałowych. Zaproponowano sposób pobudzania instrumentu, który pozwolił na wykonywane badań w sposób powtarzalny. Opisano metodologię wykonanych pomiarów oraz algorytm do analizy pomiarów wykonanych metodą optyczną, który umożliwił przetworzenie zarejestrowanego obrazu na sygnał foniczny. Na koniec zaprezentowano otrzymane wyniki z wszystkich modalności oraz wnioski z analiz.

EN

The article presents string vibration measurements carried out using fast vision cameras, a microphone and an accelerometer. Various types of acoustic guitars were selected for testing. The phenomena occurring in the instrument during the creation and extraction of sound from it were described. The aim of the study was to examine the differences in the results obtained through measurements made with different modalities and to determine which method gives the most accurate results. The measurements were carried out in an anechoic chamber, due to the need to maintain the closest possible ambient conditions during all measurements. A method of stimulating the instrument was proposed, which allowed for repeated tests. High-speed industrial cameras have enabled the recording of vibrations of selected points of the measured object. The work describes the methodology of measurements taken and the algorithm for analyzing measurements made using the optical method, which enabled the recorded image to be converted into an audio signal. The process of developing measurement data was discussed. Finally, the results obtained from all modalities and conclusions from the analyses were presented, and the possibilities of further experiments were proposed.

4

Applicability of the Capstan Equation to Guitar Strings

Groves Tom, Kemp Jonathan A.

Archives of Acoustics

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2019

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Vol. 44, No. 3

459--465

EN

The effects of friction were observed in electric guitar strings passing over an electric guitar saddle. The effects of changing the ratio of the diameter of the winding to the diameter of the core of the string, the angle through which the string is bent, and the length on either side of the saddle were measured. Relative tensions were deduced by plucking and measuring the frequencies of vibration of the two portions of string. Coefficients of friction consistent with the capstan equation were calculated and were found to be lower than 0.26 for wound strings (nickel plated steel windings on steel cores) and lower than 0.17 for unwound (tin plated steel) strings. The largest values of friction were associated with strings of nar rower windings and wider cores and this may be due to the uneven nature of the contact between the string and saddle for wound strings or due the surface of the windings deforming more, encouraging fresh (and therefore higher friction) metal to metal contact. It is advised to apply lubrication under the saddle to string contact point after first bringing the string up to pitch rather than before in order to prevent this fresh metal to metal contact.

5

Simple Linear Comparison of Strings in V -order

Alatabbi A., Daykin J. W., Rahman M. S., Smyth W. F.

Fundamenta Informaticae

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2015

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Vol. 139, nr 2

115--126

EN

In this paper we focus on a total (but non-lexicographic) ordering of strings called V - order. We devise a new linear-time algorithm for computing the V -comparison of two finite strings. In comparison with the previous algorithm in the literature, our algorithm is both conceptually simpler, based on recording letter positions in increasing order, and more straightforward to implement, requiring only linked lists.

6

Effect of Twist Stabilisation and Dyeing on the Structural and Physical Properties of Agricultural Strings

Czekalski J., Krucińska I., Kowalska S., Puchalski M.

Fibres & Textiles in Eastern Europe

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2013

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Vol. 21, no. 6 (102)

39--44

EN

A production technology for agricultural biodegradable strings composed of polylactide (PLA) staple fibres was developed that uses the ring spinning method. During complete relaxation, strings with an unbalanced twist tend to detwist because of torque, which can be eliminated by thermal stabilisation. This study assessed the effects of fibre twist stabilisation on the PLA crystalline structure and also analysed the effect of those crystalline structure changes on strength. In addition, some strings were dyed a dark colour to analyse the effect of dyeing on the structural and physical properties. Dyeing at 80 - 90 ºC with a TERASIL Schwarz B, dyeing with a TERASIL Schwarz W-NS without a carrier and stabilising undyed strings in water at 80 ºC resulted in considerable reduction in unbalanced twist while maintaining a reasonable tenacity of 10 cN/tex. The quality of the strings processed met the requirements for application in horticulture.

PL

W ramach realizacji projektu badawczego Biogratex opracowano technologię wytwarzania rolniczych sznurków biodegradowalnych z włókien PLA. Jego właściwości fizyczne dopasowane są do trudnych warunków panujących na polu i w szklarni. Sznurek charakteryzuje się, między innymi, miękkością w dotyku przez co staje się przyjazny dla roślin. Istotnym osiągnięciem jest opracowanie metod barwienia sznurków z włókien PLA i ocena wpływu warunków barwienia na strukturę polimeru oraz właściwości użytkowe sznurków.

7

Badanie drgań struny

Grodzicki M., Wasielewski R.

Aparatura Badawcza i Dydaktyczna

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2012

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T. 17, nr 1

13-17

PL

Niniejsza publikacja opisuje prosty zestaw dydaktyczno-pomiarowy zawierający drgającą strunę. Pozwala on na wprowadzenie studenta w świat drgań, ich rejestracji oraz analizy. Ponadto umożliwia pomiar gęstości materiału, z którego wykonana jest drgająca struna. Ideą przewodnią ćwiczenia jest płynne przejście od analizy ruchu drgającego do poznania właściwości fizycznych drgającego materiału (tu w postaci struny). Wykorzystanie współczesnych środków badawczych czynią proces poznawczy intuicyjnym i przyjaznym studentom. Autorzy prezentują stanowisko doświadczalne oraz ilustrują jego działanie wykonanymi pomiarami.

EN

In this paper described is an educational kit containing a vibrating string. The simple model permits the student to enter the world of vibrations, to record and analyze the phenomena. It also allows measurement of the density of the material from which the vibrating string is made. The essence of the exercise is fluent transition from analyzing the oscillating motion to learning the physical properties of a vibrating material (the string) by using contemporary means and in the form intelligible for the student. The authors present the experimental stand and illustrate its performance with standard measurements.

8

Badanie wpływu zmiennych warunków otoczenia na odpowiedź dynamiczną konstrukcji z betonów sprężonych

Mączak J., Szczurowski K.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

|

2010

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z. 5/81

111-117

PL

Podczas prowadzenia badań w ramach projektu COST Action 534 zaproponowano nową metodę oceny stanu technicznego konstrukcji z betonów sprężonych opartą o analizę efektów modulacyjnych w sygnale wibroakustycznym. Metoda pozwala na ocenę stanu technicznego konstrukcji poprzez analizę związków pomiędzy rozkładem naprężeń w przekroju poprzecznym i zmianami parametrów sygnału wibroakustycznego. Jest ona oparta na założeniu, że postępującemu uszkodzeniu cięgien napinających towarzyszy zmiana rozkładu naprężeń w przekroju poprzecznym konstrukcji sprężonej. Poprzez analizę tej zmiany powinna być zatem możliwa ocena stopnia utraty funkcjonalności cięgien, tj. ich uszkodzenie. W pracy przedstawiono wyniki badań nad wpływem warunków podparcia, oraz warunków klimatycznych na zmiany odpowiedzi dynamicznej obiektu.

EN

During the COST Action 534 a new method of evaluating the technical condition of prestressed concrete structures based on amplitude modulation effects in the vibroacoustic signal was proposed. The method allows for the evaluation of a structure’s condition by analysis of relationships between the distribution of stress in its cross-section and changes of vibroacoustic signal parameters. It is based on the assumption that the progress of tendon failures is accompanied by a change of stress distribution in the cross-section of a concrete structure. By detecting a change of a stress distribution it should be possible to diagnose the loss of functionality of tendons i.e. their failure.

9

Finding Patterns In Given Intervals

Crochemore M., Iliopoulos C.S., Kubica M., Rahman M.S., Waleń T.

Fundamenta Informaticae

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2010

|

Vol. 101, nr 3

173-186

EN

In this paper, we study the pattern matching problem in given intervals. Depending on whether the intervals are given a priori for pre-processing, or during the query along with the pattern or, even in both the cases, we develop efficient solutions for different variants of this problem. In particular, we present efficient indexing schemes for each of the above variants of the problem.

10

Cellular automata in nonlinear string vibration

Glabisz W.

Archives of Civil and Mechanical Engineering

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2010

|

Vol. 10, no 1

27-41

EN

Cellular automata procedure for the analysis of nonlinear viscously damped transverse string vibrations was defined. Parameters were obtained by comparing the cellular automata defining rules with relations resulting from the discrete form of the mathematical description of the investigated phenomenon. A series of numerical tests that were run confirmed the agreement between the obtained results and the solutions found in the literature. Numerical results demonstrate that cellular automata can constitute a simple and effective tool for the analysis of a range of complex problems which have not been analyzed in this way before.

PL

W artykule zdefiniowano procedurę automatów komórkowych, którą przystosowano do analizy nieliniowych, wiskotycznie tłumionych drgań poprzecznych struny. Parametry automatów komórkowych otrzymano porównując reguły definiujące ewolucję CA ze związkami wprost wynikającymi z dyskretnej postaci matematycznego opisu zjawiska. Przeprowadzono szereg testów numerycznych potwierdzających jakościową i ilościową zgodność otrzymywanych wyników z rozwiązaniami znanymi z literatury. Wykonane testy numeryczne pokazują, że automaty komórkowe mogą być prostym i skutecznym narzędziem analizy szeregu złożonych zagadnień dotychczas tym sposobem nie analizowanych.

11

Combinatorics of Unique Maximal Factorization Families (UMFFs)

Daykin D.E., Daykin J.W., Smyth W.F. (Bill)

Fundamenta Informaticae

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2009

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Vol. 97, nr 3

295-309

EN

Suppose a set W of strings contains exactly one rotation (cyclic shift) of every primitive string on some alphabet Σ. Then W is a circ-UMFF if and only if every word in Σ+ has a unique maximal factorization over W. The classic circ-UMFF is the set of Lyndon words based on lexicographic ordering (1958). Duval (1983) designed a linear sequential Lyndon factorization algorithm; a corresponding PRAMparallel algorithmwas described by J. Daykin, Iliopoulos and Smyth (1994). Daykin and Daykin defined new circ-UMFFs based on various methods for totally ordering sets of strings (2003), and further described the structure of all circ-UMFFs (2008). Here we prove new combinatorial results for circ-UMFFs, and in particular for the case of Lyndon words. We introduce Acrobat and Flight Deck circ-UMFFs, and describe some of our results in terms of dictionaries. Applications of circ-UMFFs pertain to structured methods for concatenating and factoring strings over ordered alphabets, and those of Lyndon words are wide ranging and multidisciplinary.

12

Statistical characteristics of the damped vibrations of a string excited by stochastic forces

Jabłoński M., Ozga A.

Archives of Acoustics

|

2009

|

Vol. 34, No. 4

601-612

EN

Our theoretical study aims at finding some statistic parameters characterizing the damped vibrations of a string excited by stochastic impulses. We derive the dependence of these parameters on the parameters of the string as well as on the stochastic distributions of the impulse magnitude, and on the place of the action. We also carry out a numerical simulation verifying the derived mathematical model and interpret the differences between the results obtained in simulation and the mathematical calculations. This study is the fourth stage of a research aimed at designing a probe that facilitates the process of measuring of the parameters, determining the quality of a technological process.

13

Dynamiczne efekty działania obciążenia użytkowego na cięgno nośne napowietrznej kolei dwulinowej

Knawa M., Bryja D.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

|

2008

|

z. 74 [258]

135-142

EN

The model of a carrying rope of a bicable ropeway system under in-service loads is introduced to analyze dynamic response of the cable during: start and steady ride of passenger carriers, an emergency stop of operating system. The pendulum model of amoving carrier is formulated to define loads acting on the cable. Equations of motion of system composed of continuous cable and a set of traveling pendulums are derived by applying Ritz approximate method and Lagrangian description of motion. Some illustrative numerical results are presented to demonstrate applicability of proposed method in an analysis of cable vibrations.

14

String-beam under moving inertial load

Dyniewicz B., Bajer C.

Vibrations in Physical Systems

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2008

|

Vol. 23

115--120

EN

The paper deals with the original analytical-numerical approach to the Bernoulli-Euler beam with additional tensile effect under a moving inertial load. The authors applied the 2nd kind Lagrange equation to derive a motion differential equation of the problem. The moving mass can travel through the string-beam with a whole range constant speed, also overcritical. The analytical solution requires a numerical calculation in the last stage and is called a semi-analytical one.

15

Statistical characteristics of vibrations of a string forced by stochastic forces

Jabłoński M., Ozga A.

Mechanics / AGH University of Science and Technology

|

2008

|

Vol. 27, no. 1

1-7

EN

Our theoretical study aims at finding the statistical parameters characterizing the vibrations of a string without damping and forced by stochastic impulses when the places and moments of actions are random. We derive the dependence of these parameters from the parameters of the string as well as from the stochastic distributions of the impulse magnitude, and of the place of the action. We also carry out a numerical simulation verifying the derived mathematical model and interpret the differences between the results obtained in the simulation and the mathematical calculations. This study is the third stage of research aimed at designing and calibrating a probe that will facilitate measuring of parameters determining the quality of a technological process.

PL

Celem badań teoretycznych w tej pracy jest znalezienie parametrów charakteryzujących drgania struny bez tłumienia i będącej pod wpływem działania sił impulsowych, dla których miejsce i moment zadziałania są przypadkowe. Zostanie wyprowadzona zależność tych parametrów od parametrów struny oraz zarówno od stochastycznego rozkładu wielkości impulsu, jak i rozkładu miejsca zadziałania siły. Przeprowadzono również symulację numeryczną weryfikującą wyprowadzony model matematyczny oraz zinterpretowano różnice pomiędzy wynikami otrzymanymi z symulacji a obliczeniami teoretycznymi. Badania te są trzecim etapem prac mających na celu zaprojektowanie i skalibrowanie sondy, która umożliwi dokonywanie pomiarów parametrów określających jakość procesu technologicznego.

16

Some Alternatives to Parikh Matrices Using String Kernels

Clark A., Watkins C.

Fundamenta Informaticae

|

2008

|

Vol. 84, nr 3-4

291-303

EN

We describe methods of representing strings as real valued vectors or matrices; we show how to integrate two separate lines of enquiry: string kernels, developed in machine learning, and Parikh matrices [8], which have been studied intensively over the last few years as a powerful tool in the study of combinatorics over words. In the field of machine learning, there is widespread use of string kernels, which use analogous mappings into high dimensional feature spaces based on the occurrences of subwords or factors. In this paper we show how one can use string kernels to construct two alternatives to Parikh matrices, that overcome some of the limitations of the Parikh matrix construction. These are morphisms from the free monoid to rings of real-valued matrices under multiplication: one is based on the subsequence kernel and the other on the gap-weighted string kernel. For the latter kernel we demonstrate that for many values of the gap-weight hyper-parameter the resulting morphism is injective.

17

Identyfikacja stanu napięcia cięgien zwieszenia komory paleniskowej kotła energetycznego

Górski A., Iluk A., Kowalczyk M., Wyszyński J.

Górnictwo Odkrywkowe

|

2006

|

R. 48, nr 5-6

141-143

PL

Jednym z problemów eksploatacyjnych komory paleniskowej oraz konwekcyjnej jest ich specyficzny sposób podwieszania na 97 cięgnach. Istotną role odgrywa tu odpowiedni rozdział sił na poszczególne cięgna. Efektem różnic pomiędzy siłami są koncentracje naprężeń w ścianach, a także pojawienie się niepożądanych ruchów komory. W celu oszacowania efektów takich zjawisk przeprowadzono identyfikację stanu napięcia poszczególnych cięgien metodą analizy częstotliwości drgań własnych. Przedstawiono wyniki pomiarów częstotliwości drgań własnych oraz obliczeń numerycznych metodą elementów skończonych.

EN

One of the operating problems of the furnace and convection chamber is the specific way of its suspension on the 97 strings. In this case the equivalent reaction forces distribution in particular strings has a significant part. The stresses concentrations in the chamber walls as well as the appearance of unwanted movements are the effect of diversified forces distribution. Hence, in order to eliminate these kinds of effects the identification particular strings tension state with the use of method of frequency of free vibrations analysis was conducted. The results of free vibrations frequency measurements as well as results of numerical calculations with the use of finite element method are presented.

18

Odkształcenia betonu sprężonego w młodym wieku

Szydłowski R.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

|

2005

|

z. 104

347-354

PL

Na skutek termicznej i skurczowej zmiany objętości beton skrępowany więzami zewnętrznymi i wewnętrznymi ulega zarysowaniu we wczesnej fazie dojrzewania. W pracy przedstawiono fragment podjętych w ramach pracy doktorskiej badań nad zastosowaniem sprężenia cięgnami bezprzyczepnościowymi jako metody zapobiegawczej. Przedstawiono wyniki odkształceń betonu zmiany siły sprężającej w czasie w sprężonej jednokierunkowo płycie o wymiarach 1,0 x 3,6 x 0,16 m. Płyta sprężona została dwoma splotami 7 na 5 mm w dwóch etapach po 20 i 43,5 godz. od zaformowania do średnich naprężeń odpowiednio 1,25 i 2,5 Mpa. Omówiono wyniki oraz wnioski i zalecenia do dalszych badań.

EN

In this paper the first stage of the research on the application of unbonded tendons to eliminate the thermal and shrinkage cracking of the early-age concrete has been presented. The concrete slab 1,0 x 3,6 x 0,16 m has been casted and prestressed by two unbonded steel tendons 7 upon 5 mm, 20 hours after concrete casting. The final value of initial prestressing force equal to 190 kN has been realized 43,5 hours from concrete casting. The concrete strains as well as the prestress force decrease have been presented and discussed. The final conclusion and the proposition for further investigation are presented.

19

On Equations Including Strings

Kopeček I., Novotny M.

Fundamenta Informaticae

|

2002

|

Vol. 51, nr 4

391-398

EN

A system of equations is solved where the right side member of any equation is a known string and the left side member is formed by concatenation of some unknown strings. This problem appears in connection with the division of parts of speech into syllable segments.

20

The damped vibrating strings under stochastic forces

Ebady A. M., El-Tawil G. E.

Mechanics and Mechanical Engineering

|

1999

|

Vol. 3, nr 1

15--25

EN

The solution of the stochastic wave equation under damping coefficient and stochastic forces is considered in this paper using the finite sine transform method . The equation represents a damped vibrating string under a stochastic force. The ensemble average and variance of the string deflection are computed in general expressions and then relaxed to the case of the modulated white noise. A case study is considered to illustrate the reliability on the present analysis.