Overturning Thresholds of a Rocking Block Subjected to Harmonic Excitation: Computer Simulations and Analytical Treatment

2003 ◽  
Author(s):  
Stefano Lenci ◽  
Giuseppe Rega
Keyword(s):  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Point Of View ◽  
Theoretical Point ◽  
Rigid Block ◽  
Periodic Excitation ◽  
Analytical Treatment ◽  
Rocking Block ◽  
Combined Use ◽  
Analytical Tools

When a rigid block resting on a horizontal rigid foundation is shaken by a periodic excitation it can topples if the excitation amplitude is sufficiently high. This question is addressed in this work by the combined use of numerical and analytical tools. Numerical computations are first performed aimed at understanding the overall overturning behavior, and how it is modified by varying relevant parameters, such as the excitation phase and the coefficient of restitution at impacts. Then the problem is addressed from a theoretical point of view, with the objective of analytically detecting the most relevant features highlighted by previous numerical simulations. We succeed in obtaining closed form and manageable criteria for overturning.

scholarly journals Encounter in the Keplerian Field: Analytical Treatment

1993 ◽  
Vol 132 ◽  
pp. 289-289
Author(s):  
V.A. Brumberg ◽  
T.V. Ivanova
Keyword(s):  
Point Of View ◽  
Lunar Theory ◽  
Theoretical Point ◽  
The Sun ◽  
The Moon ◽  
Type Solution ◽  
Analytical Treatment ◽  
Hill’S Problem ◽  
Hill's Problem ◽  
Resonance Character

AbstractIn extending the results of Henon and Petit (Celes.Mech., 38,67, 1986) an algorithm is suggested to construct the series representing the general encounter-type solution of the spatial eccentric Hill’s problem. The series are arranged in powers of the eccentricity E of Hill’s problem and two integration constants e and k characterizing eccentricity and inclination of the relative motion. A particular non-periodic solution of Henon and Petit corresponding to E = e = k = 0 is taken as an intermediary. The perturbations to this solution are constructed similar to the Lunar theory of Hill and Brown with; the Universal Poissonian Processor. From theoretical point of view Hill’s problem for the encounter case is of particular interest. In distinction from the Lunar problem we do not have here angular arguments with different frequencies. Moreover, the perturbations related with the external eccentricity E (analogous to the perturbations in the motion of the motion of the Moon caused by the eccentricity of the orbit of the Sun) are of resonance character.

Rocking Vibration of Rigid Block Under Horizontal Harmonic Excitation With Noise

2015 ◽  
Author(s):  
ManYong Jeong
Keyword(s):  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Rigid Block ◽  
Contact Conditions ◽  
Normal Probability ◽  
Fluctuation Range ◽  
Experimental Works ◽  
Rocking Vibration ◽  
Normal Probability Distribution ◽  
Rocking Response

This study deals with the rocking behavior of a rigid block subjected to horizontal harmonic excitations with minute fluctuation. Nonlinear rocking behaviors may be often accompanied by minute changes of rocking system parameters, such as friction and restitution coefficients, depending on contact conditions between the block and the base. In this paper, the minute fluctuation of excitation amplitude is imitated by random numbers with normal probability distribution and the fluctuation range is adjusted by their standard deviation. Analytical results in our previous studies have shown that rocking responses are very sensitive to small changes of friction coefficients and noise included in the excitation and the distribution of rocking response is greatly affected by the effects. Nonrecurring rocking responses observed in our previous experimental works have been reproduced by simulation considering minute fluctuation of excitation amplitude. Minute changes of excitation amplitude make the rocking response unstable and aperiodic, and distribution of rocking responses is also massively changed by adding the excitation noise.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

A novel cryptosystem based on abstract automata and Latin cubes

2015 ◽  
Vol 52 (2) ◽  
pp. 221-232
Author(s):  
Pál Dömösi ◽  
Géza Horváth
Keyword(s):  
Block Cipher ◽  
Finite Automata ◽  
Theoretical Background ◽  
Point Of View ◽  
Theoretical Point ◽  
Transition Matrices ◽  
Encryption And Decryption ◽  
Secret Keys ◽  
Automata Network ◽  
Fully Functioning

In this paper we introduce a novel block cipher based on the composition of abstract finite automata and Latin cubes. For information encryption and decryption the apparatus uses the same secret keys, which consist of key-automata based on composition of abstract finite automata such that the transition matrices of the component automata form Latin cubes. The aim of the paper is to show the essence of our algorithms not only for specialists working in compositions of abstract automata but also for all researchers interested in cryptosystems. Therefore, automata theoretical background of our results is not emphasized. The introduced cryptosystem is important also from a theoretical point of view, because it is the first fully functioning block cipher based on automata network.

Graffiti als Version und Subversion–Praxen kultureller Re-Regulierung und die Möglichkeit von Gratiforschung

2010 ◽  
Vol 55 (2) ◽  
pp. 11-25 ◽  
Author(s):  
Bernd Dollinger
Keyword(s):  
Social Life ◽  
Point Of View ◽  
Theoretical Point ◽  
Research Practice ◽  
Wird Eine ◽  
Multiple Perspectives

Der Beitrag geht von Versuchen aus, integrative Perspektiven einer überaus heterogenen Graffitiforschung zu bestimmen. In Auseinandersetzung insbesondere mit Bruno Latours Ansatz des »Iconoclash« wird eine kulturtheoretische Referenz bestimmt, die Graffiti als Version identifiziert, d. h. als semiotisch orientierte Veränderung räumlich situierter Ordnungs- und Regulierungspraxen. Ihnen kann, wenn auch nicht zwingend, eine subversive Qualität zukommen. Durch die Ausrichtung am Konzept einer Version wird beansprucht, Forderungen einer normativ weitgehend abstinenten, nicht-essentialistischen und für komplexe Fragen der Identitäts- und Raumpolitik offenen Forschungspraxis einzulösen.<br><br>The contribution attempts to integrate multiple perspectives of current largely heterogeneous graffiti scholarship. Referring to Bruno Latour’s concept »iconoclash«, we discuss graffiti from a cultural-theoretical point of view as a »version«. It appears as a semiotically oriented modification of spatially situated practices that regulate social life. Often, but not necessarily, these practices involve subversive qualities. The concept of »version« facilitates a non-normative and non-essentialist strategy of research. This enables an explorative research practice in which the complex matters of identity and space politics that are associated with graffiti can be addressed.

scholarly journals How Digital Inclusion Increase Opportunities for Young People: Case of NEETs from Bulgaria, Romania and Turkey

2021 ◽  
Vol 13 (14) ◽  
pp. 7894
Author(s):  
Gabriela Neagu ◽  
Muhammet Berigel ◽  
Vladislava Lendzhova
Keyword(s):  
Data Analysis ◽  
Rural Areas ◽  
Secondary Data ◽  
Point Of View ◽  
Multidimensional Analysis ◽  
Theoretical Point ◽  
Digital Inclusion ◽  
Virtual Mobility ◽  
Alternative Research ◽  
High Share

This paper examines the perspectives of rural NEETs in the information society. Our analysis focuses on the situation of three European countries—Bulgaria, Romania, and Turkey—characterized by a high share of rural areas and a population of NEETs. From a methodological point of view, we use alternative research methods (secondary data analysis) with statistical methods (simple linear regression). From a theoretical point of view, we will opt for a multidimensional analysis perspective: the theory of digital divide, digital inclusion, virtual mobility, etc. Through data analysis, we expect to obtain a more complete and detailed picture of the ICT situation in rural areas (level of digital skills, level of digital inclusion) to demonstrate the importance of ICT in optimizing virtual mobility for the living conditions of the population, especially the NEET population.

scholarly journals Verbena officinalis Verbenaceae (Lamiales): a new plant model system for phyllotaxis research

2021 ◽  
Author(s):  
Beata Zagórska-Marek ◽  
Magdalena Turzańska ◽  
Klaudia Chmiel
Keyword(s):  
Vascular System ◽  
Cumulative Effect ◽  
Point Of View ◽  
Theoretical Point ◽  
Inflorescence Axis ◽  
Organ Identity ◽  
Lateral Organ ◽  
Complex Relationships ◽  
Secondary Transitions

AbstractPhyllotactic diversity and developmental transitions between phyllotactic patterns are not fully understood. The plants studied so far, such as Magnolia, Torreya or Abies, are not suitable for experimental work, and the most popular model plant, Arabidopsis thaliana, does not show sufficient phyllotactic variability. It has been found that in common verbena (Verbena officinalis L.), a perennial, cosmopolitan plant, phyllotaxis differs not only between growth phases in primary transitions but also along the indeterminate inflorescence axis in a series of multiple secondary transitions. The latter are no longer associated with the change in lateral organ identity, and the sequence of phyllotactic patterns is puzzling from a theoretical point of view. Data from the experiments in silico, confronted with empirical observations, suggest that secondary transitions might be triggered by the cumulative effect of fluctuations in the continuously decreasing bract primordia size. The most important finding is that the changes in the primary vascular system, associated with phyllotactic transitions, precede those taking place at the apical meristem. This raises the question of the role of the vascular system in determining primordia initiation sites, and possibly challenges the autonomy of the apex. The results of this study highlight the complex relationships between various systems that have to coordinate their growth and differentiation in the developing plant shoot. Common verbena emerges from this research as a plant that may become a new model suitable for further studies on the causes of phyllotactic transitions.

scholarly journals Modeling and theoretical description of magnetic hybrid materials—bridging from meso- to macro-scales

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Andreas M. Menzel ◽  
Hartmut Löwen
Keyword(s):  
Colloidal Particles ◽  
Colloidal Particle ◽  
Theoretical Description ◽  
Point Of View ◽  
Material Behavior ◽  
Theoretical Point ◽  
Mechanical Stiffness ◽  
Theoretical Approaches ◽  
Theoretical Predictions ◽  
Particle Level

Abstract Magnetic gels and elastomers consist of magnetic or magnetizable colloidal particles embedded in an elastic polymeric matrix. Outstanding properties of these materials comprise reversible changes in their mechanical stiffness or magnetostrictive distortions under the influence of external magnetic fields. To understand such types of overall material behavior from a theoretical point of view, it is essential to characterize the substances starting from the discrete colloidal particle level. It turns out that the macroscopic material response depends sensitively on the mesoscopic particle arrangement. We have utilized and developed several theoretical approaches to this end, allowing us both to reproduce experimental observations and to make theoretical predictions. Our hope is that both these paths help to further stimulate the interest in these fascinating materials.

The expectation marker of course in a cross-linguistic perspective

2004 ◽  
Vol 4 (1) ◽  
pp. 13-43 ◽  
Author(s):  
Anne-Marie Simon-Vandenbergen ◽  
Karin Aijmer
Keyword(s):  
English Learners ◽  
Native Speakers ◽  
Point Of View ◽  
Theoretical Point ◽  
Pragmatic Markers ◽  
Semantic Fields ◽  
Explanatory Account ◽  
Semantics And Pragmatics ◽  
Multilingual Corpus ◽  
Core Meaning

The study of of course presented in this article has an applied, a descriptive and a theoretical aim. Since of course proves to be very frequent in English, learners will need to know what meanings the item has and in what pragmatic contexts it is used. It has indeed been shown that some learners tend to use of course in contexts where it is felt by native speakers to be inappropriate. In order to explain such inappropriate uses we need detailed descriptions of the semantics and pragmatics of of course. From a theoretical point of view such multifunctional items raise the question of whether semantic polysemy or pragmatic polysemy is the best explanatory account. It is argued in this paper that empirical cross-linguistic work can contribute to providing answers to all three research questions. First, the study of correspondences and differences between languages with regard to the meanings and uses of pragmatic markers is a necessary step in the explanation of learner problems. Second, the bidirectional approach to equivalents, which involves going back and forth from sources to translations, enables us to show to what extent the equivalents have partially overlapping pragmatic functions. An in-depth comparison of the semantic fields in which the translation equivalents operate is the ultimate goal. Third, the translation method helps to see to what extent a core meaning account is justified. In this paper three languages are brought into the picture, viz. English, Swedish and Dutch. The cross-linguistic data have been gathered from three translation corpora, i.e. the English-Swedish Parallel Corpus, the Oslo Multilingual Corpus and the Namur Triptic Corpus.

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