Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 34
items per page: 25 50 75
Sort by:

Abstract

The lithostratigraphy, biostratigraphy, sequence stratigraphy, ammonite and inoceramid faunas of the Upper Albian, Cenomanian, and Lower Turonian Karai Formation, the highest unit of the Uttatur Group in the Pondicherry Sub-Basin of the Cauvery Basin in Tamil Nadu, south India, are documented. Detailed logs and descriptions of sections between Karai and Kulakkalnattam, Odiyam and Kunnam, and north-west of Garudamangalam are presented. They provide the evidence for an ammonite zonal scheme that can be correlated in detail with sequences developed in Europe, with successive Upper Albian zones of Pervinquieria (Subschloenbachia) rostrata and P. (S.) perinflata (the latter on slight evidence), Cenomanian zones of Mantelliceras mantelli, Cunningtoniceras cunningtoni, Calycoceras (Newboldiceras) asiaticum, Pseudo calycoceras harpax, Euomphaloceras septemseriatum and Pseudspidoceras footeanum. The Lower Turonian is represented by a Neoptychites cephalotus–Mytiloides borkari fauna. Over 120 ammonite species are described, of which Puzosia (Bhimaites) falx, Protacanthoceras parva, Watinoceras elegans, Euomphaloceras varicostatum, Kamerunoceras multinodosum, and Carthaginites multituberculatus are new. The new genus Kunnamiceras, with Ammonites tropicus Kossmat, 1865 as type species, is interpreted as a paedomorphic dwarf derivative of Pseudocalycoceras harpax (Stoliczka, 1864). Ammonite faunas from shales are dominated by feebly-ornamented taxa: leiostraca; those from sandstones by strongly ornamented taxa: trachyostraca, differences interpreted as reflecting the preferred habits of adults in life. 15 species of inoceramid bivalves, including a newly described species Inoceramus chiplonkari, are recognised, with a mixed East African–Euramerican–North Pacific affinity. On the basis of the stratigraphic framework developed, a sequence stratigraphic interpretation of the Karai Formation is proposed, and correlated with those recognised in Europe, Morocco, and the United States Gulf Coast and Western Interior.
Go to article

Abstract

The positivity and absolute stability of a class of nonlinear continuous-time and discretetime systems are addressed. Necessary and sufficient conditions for the positivity of this class of nonlinear systems are established. Sufficient conditions for the absolute stability of this class of nonlinear systems are also given.
Go to article

Abstract

The methane hazard is one of the most dangerous phenomena in hard coal mining. In a certain range of concentrations, methane is flammable and explosive. Therefore, in order to maintain the continuity of the production process and the safety of work for the crew, various measures are taken to prevent these concentration levels from being exceeded. A significant role in this process is played by the forecasting of methane concentrations in mine headings. This very problem has been the focus of the present article. Based on discrete measurements of methane concentration in mine headings and ventilation parameters, the distribution of methane concentration levels in these headings was forecasted. This process was performed on the basis of model-based tests using the Computational Fluid Dynamics (CFD). The methodology adopted was used to develop a structural model of the region under analysis, for which boundary conditions were adopted on the basis of the measurements results in real-world conditions. The analyses conducted helped to specify the distributions of methane concentrations in the region at hand and determine the anticipated future values of these concentrations. The results obtained from model-based tests were compared with the results of the measurements in realworld conditions. The methodology using the CFD and the results of the tests offer extensive possibilities of their application for effective diagnosis and forecasting of the methane hazard in mine headings.
Go to article

Abstract

We derive exact and approximate controllability conditions for the linear one-dimensional heat equation in an infinite and a semi-infinite domains. The control is carried out by means of the time-dependent intensity of a point heat source localized at an internal (finite) point of the domain. By the Green’s function approach and the method of heuristic determination of resolving controls, exact controllability analysis is reduced to an infinite system of linear algebraic equations, the regularity of which is sufficient for the existence of exactly resolvable controls. In the case of a semi-infinite domain, as the source approaches the boundary, a lack of L2-null-controllability occurs, which is observed earlier by Micu and Zuazua. On the other hand, in the case of infinite domain, sufficient conditions for the regularity of the reduced infinite system of equations are derived in terms of control time, initial and terminal temperatures. A sufficient condition on the control time, heat source concentration point and initial and terminal temperatures is derived for the existence of approximately resolving controls. In the particular case of a semi-infinite domain when the heat source approaches the boundary, a sufficient condition on the control time and initial temperature providing approximate controllability with required precision is derived.
Go to article

Abstract

Given a linear discrete system with initial state x0 and output function yi , we investigate a low dimensional linear systemthat produces, with a tolerance index ǫ, the same output function when the initial state belongs to a specified set, called ǫ-admissible set, that we characterize by a finite number of inequalities. We also give an algorithm which allows us to determine an ǫ-admissible set.
Go to article

Abstract

The paper addresses the problem of constrained pole placement in discrete-time linear systems. The design conditions are outlined in terms of linear matrix inequalities for the Dstable ellipse region in the complex Z plain. In addition, it is demonstrated that the D-stable circle region formulation is the special case of by this way formulated and solved pole placement problem. The proposed principle is enhanced for discrete-lime linear systems with polytopic uncertainties.
Go to article

Abstract

We study an elegant snap system with only one nonlinear term, which is a quadratic nonlinearity. The snap systemdisplays chaotic attractors,which are controlled easily by changing a system parameter. By using analysis, simulations and a real circuit, the dynamics of such a snap system has been investigated. We also investigate backstepping based adaptive control schemes for the new snap system with unknown parameters.
Go to article

Abstract

This paper presents a concept of humanoid robot motion generation using the dedicated simplified dynamic model of the robot (Extended Cart-Table model). Humanoid robot gait with equal steps length is considered. Motion pattern is obtained here with use of Preview Control method. Motion trajectories are first obtained in simulations (off-line) and then they are verified on a test-bed. Tests performed using the real robot confirmed the correctness of the method. Robot completed a set of steps without losing its balance.
Go to article

Abstract

This paper presents a robust control technique for small-scale unmanned helicopters to track predefined trajectories (velocities and heading) in the presence of bounded external disturbances. The controller design is based on the linearized state-space model of the helicopter. The multivariable dynamics of the helicopter is divided into two subsystems, longitudinallateral and heading-heave dynamics respectively. There is no strong coupling between these two subsystems and independent controllers are designed for each subsystem. The external disturbances and model mismatch in the longitudinal-lateral subsystem are present in all (matched and mismatched) channels. This model mismatch and external disturbances are estimated as lumped disturbances using extended disturbance observer and an extended disturbance observer based sliding mode controller is designed for it to counter the effect of these disturbances. In the case of heading-heave subsystem, external disturbances and model mismatch only occur in matched channels so a second order sliding mode controller is designed for it as it is insensitive to matched uncertainties. The control performance is successfully tested in Simulink.
Go to article

Abstract

This work describes a new study to achieve a combination of modified function projective synchronization between three different chaotic systems through adaptive control. Using the Lyapunov function theory, the asymptotic stability of the error dynamics is obtained and discussed. Further, we set some appropriate initial conditions for the state variables and assigning specific values to the parameters and obtain the graphical results, which shows the efficiencies of the new method. Finally, we summarized our work with conclusion and references.
Go to article

Abstract

The LQR (linear quadratic regulator) control problem subject to singular system constitutes a optimization problem in which one must be find an optimal control that satisfy the singular system and simultaneously to optimize the quadratic objective functional. In this paper we establish a sufficient condition to obtain the optimal control of discounted LQR optimization problem subject to disturbanced singular system where the disturbance is time varying. The considered problem is solved by transforming the discounted LQR control problem subject to disturbanced singular system into the normal LQR control problem. Some available results in literatures of the normal LQR control problem be used to find the sufficient conditions for the existence of the optimal control for discounted LQR control problem subject to disturbanced singular system. The final result of this paper is in the form a method to find the optimal control of discounted LQR optimization problem subject to disturbanced singular system. The result shows that the disturbance is vanish with the passage of time.
Go to article

Abstract

This paper presents the design of digital controller for longitudinal aircraft model based on the Dynamic Contraction Method. The control task is formulated as a tracking problem of velocity and flight path angle, where decoupled output transients are accomplished in spite of incomplete information about varying parameters of the system and external disturbances. The design of digital controller based on the pseudo-continuous approach is presented, where the digital controller is the result of continuous-time controller discretization. A resulting output feedback controller has a simple form of a combination of low-order linear dynamical systems and a matrix whose entries depend nonlinearly on certain known process variables. Simulation results for an aircraft model confirm theoretical expectations.
Go to article

Abstract

The article is a contribution to the methodology of reading and interpreting Dostoevsky’s famous novels. It owes its genesis to the refl ection upon the evolution of literary theory discourse in XX century and upon transformations in global (mainly Russian and Western) reception and modes of interpreting the oeuvre of the great Russian artist. The aim of the text is to prepare ground for reorienting Polish “dostoevskology” from the dominant reconstructive course onto the more creative, interpretative one. The order of my inquiries presents itself as follows. In the fi rst part of the article I focus on the questions of ideas, the protagonist and narrative techniques in Dostoevsky so that to highlight the specifi city of the writer’s approach to these issues. It will allow me to speak up for the minimum of methodological awareness which implies acknowledgment of the paradigm of polyphony, polysemy and complexity of Dostoevsky’s text. Perhaps it will also become possible to reveal some gaps in the hitherto existing state of research, debunk several stereotypes still functioning in Polish “dostoevskology”, and draw attention to still unrecognized interpretative clues in context of those crucial aspects of Dostoevsky’s work. In the second part I will reconstruct several most popular approaches to Dostoevsky’s text which differ in terms of understanding of what the relation between the reader and the text should comprise of. I will try to determine the benefi ts they can bring but also to sensitize to pitfalls they may entail. In the fi nal, third part of the study I will propose a project of a new interpretative approach which would rise to the challenge of Dostoevsky’s “spirit” as well as the spirit of his text the way it is construed by the most advanced contemporary critical studies and as I have learnt to perceive it.
Go to article

Abstract

The article focuses on the term “train situation” created by Vyacheslav Kuricin, which is considered a metaphor of the work of the contemporary Russian writer Elena Dolgopyat. The proper analysis of Dolgopyat’s works is preceded by an introduction in which the definition of magical realism and its history in Russia is briefl y presented. The attitude of the Russian literary scholars to this phenomenon is presented as well. Next, the meanings of the figure of train in the writer’s stories are discussed. It is noteworthy that the features of magical realism (specific space-time construction, polyphonic narrative, fantastic elements perceived as something natural) are realized in her texts often through the image of a train. In works in which this picture does not exist, we deal with the „train situation”, which boils down to the combination in the presented world of various aspects of reality, unlimited by matter. The heroes live between different dimensions of reality, and combining into one cohesive whole of various space-times, ways of existence, realistic and fantastic elements allows to see the term of Kuricin also as a metaphor of all magical realism.
Go to article

Abstract

In this article, strategies and writing tricks (the trick of “defamiliarization”, imagery) which in Nabokov’s short story A Guide to Berlin serve to design the image of the city and simultaneously to explore the world of values (axiological map of Berlin/Eden) are being interpreted. The author of this article proves that the semantics of the title guide is connected with the strategy of transition from empirical observation and one “fragment of space” to expression of a situation in which the subject of speech has found himself. Moreover, it is shown that the subjectivity of the observer, his way of experiencing the world and his creative sensitivity seem crucial in the story, because he evaluates the surrounding reality and in the “act of individual creativity” builds upon it yet another space – an unusual, transformed one, close to the emigrant/the author of the guidebook. Attention is also paid to the differentiation of two ways of perceiving the world and two types of consciousness: the artist’s/narrator’s and his listener’s (“average consciousness”).
Go to article

Abstract

The article aims to prove that the narrative structure of The Stormy Life of Lasik Roitschwantz by Ilya Ehrenburg can be viewed as a starting point for understanding the overriding idea of the novel. In the material for interpretation among other things analysed what follows: the similarity between the narrative of the fi rst few chapters and the skaz narrative (Russian oral form of narrative) based on the defi nition of formal mimesis, the introduction to a “foreign word” narrative (the protagonist using reported speech and free indirect speech), the restriction of the storyteller’s role (which is the overriding element of the skaz narrative) and simultaneously putting the protagonist at the forefront, the language markers used in order to mask the convergence between the storyteller’s and the protagonist’s points of view. As a result, the article implies that the presence of a skaz storyteller allows analysing the fi gure of Lasik Roitschwantz not as a character from a book or of a certain type, but rather as a human being in a universal sense.
Go to article

Abstract

The article is an attempt to present Józef Czechowicz’s relationships with the early works of Oleh Olzhych from the Камінь (1932) and Бронза (1932) cycles, preceding his debut collection of poems entitled Рінь (1935). Oleh Kandyba’s poems became the subject of interest of Polish literary circles as early as in the 1930s. His poems were translated mostly by writers associated with the Kamena magazine based in Chełm, a group whose member was also Józef Czechowicz. Kandyba’s poetry, described as “tragic optimism,” is to a large extent analogous with the works of the poet from Lublin. Both authors include apocalyptic and Arcadian motifs in their poems. Their compositions, based on contrast, are accompanied by Biblical and classical motifs, in which the imagery of stone played a special role. Both Olzhych and Czechowicz took care over the clarity of their poetry and focused on the right choice of words. Poems provided them with a means of escape from the realities of war and constituted a kind of an appeal to the nation.
Go to article

Abstract

Vasyl Stus is the Ukrainian existential poet, who used aesthetic of surrealism and expressionism. This text presents surreal elements in the Vasyl Stus’s poems which are connected with the idea of hell. Author gives examples of different images of hell in European culture and literature and also analyzes the surrealist poems of Vasyl Stus from his book Merry Cemetery.
Go to article

Abstract

Death is one of the key concepts present in the traditional image of the world. It means an end and is related to the process of wearing out and losing original properties. In folk anthropology, death is understood in terms of the transition from the earth world to the land of the dead, as the beginning of eternal existence. Death is one of the rites of passage and as such is correlated with other crucial moments of human existence, mainly with birth and marriage. Death is a common motif present in various genres of folklore. Researchers are interested in death predominantly because of its belief- and ritual-related image. The aim of the article is to analyse depictions of death in folk fablesand other kinds of prose works. Special emphasis is placed on the personifi cation of death as well as on its genesis and ontological status. The article also deals with the idea of death understood as both an event and a process, and it addresses death seen as a transcendental and unmaterialised force which determines a person’s life against his or her will.
Go to article

Abstract

The article shows that during the forming of grammatical category of gender in Indo-European languages, names of non-living objects and names of those animals whose sex is unimportant for humans were receiving grammatical meanings of gender on the basis of similarity or dissimilarity of designated objects with males or females. Such grammatical metaphors were based on the ideas of different peoples about some minor characteristics of persons of different sex, such as the difference between men and women with higher activity, greater size, strength and independence. By now, the metaphorical motivation of category of gender in the Russian language has survived only in certain nouns. These nouns are interrogative pronouns кто (masc.) ʻwhoʼ and что (neut.) ʻwhatʼ, paired nouns-synonyms, e. g. конь (masc.) ʻstrong horseʼ – лошадь (fem.) ʻordinary horseʼ, generic versions of nouns, e. g. ворон (masc.) ʻravenʼ – ворона (fem.) ʻcrowʼ, and nouns-occasionalisms used in speech oriented to expressiveness and creativity.
Go to article

This page uses 'cookies'. Learn more