Analysis of a frictionless contact problem for elastic-viscoplastic materials

We consider a dynamic frictionless contact problem for elastic-viscoplastic materials with damage. The contact is modelled with normal compliance condition. The adhesion of the contact surfaces is considered and is modelled with a surface variable, the bonding field whose evolution is described by a first order differential equation. We derive variational formulation for the model and prove an existence and uniqueness result of the weak solution. The proof is based on arguments of nonlinear evolution equations with monotone operators, a classical existence and uniqueness result on parabolic inequalities, differential equations and fixed-point arguments

A frictional contact problem with wear and damage for electro-viscoelastic materials

summary:We consider a quasistatic contact problem for an electro-viscoelastic body. The contact is frictional and bilateral with a moving rigid foundation which results in the wear of the contacting surface. The damage of the material caused by elastic deformation is taken into account, its evolution is described by an inclusion of parabolic type. We present a weak formulation for the model and establish existence and uniqueness results. The proofs are based on classical results for elliptic variational inequalities, parabolic inequalities and fixed point arguments

Exponential Networks and Representations of Quivers

We study the geometric description of BPS states in supersymmetric theories with eight supercharges in terms of geodesic networks on suitable spectral curves. We lift and extend several constructions of Gaiotto-Moore-Neitzke from gauge theory to local Calabi-Yau threefolds and related models. The differential is multi-valued on the covering curve and features a new type of logarithmic singularity in order to account for D0-branes and non-compact D4-branes, respectively. We describe local rules for the three-way junctions of BPS trajectories relative to a particular framing of the curve. We reproduce BPS quivers of local geometries and illustrate the wall-crossing of finite-mass bound states in several new examples. We describe first steps toward understanding the spectrum of framed BPS states in terms of such "exponential networks."Comment: 82 pages, 60 figures, typos fixe

On Form and Logic of Structures

In Civil Engineering, every structure harbours some degree of logic within it. Sometimes, it is easy to see it, while sometimes it lies somehow hidden and only a well informed eye can take hold of it. The Natural phenomena are dual in their manifestation. So are Tension and Compression, which represents the basic “genomes” of this interaction and are present within each structure from the simplest to the most complicated one. A structural form represents a physical manifestation of this invisible interplay, which, when in consonance with the natural flow of forces results not only in an economic but in a well proportionate and aesthetic structure – a work of art. Nowadays, the culture of putting unreserved belief on the results given by supercomputers slowly degraded in becoming a tradition. This paper calls for an increase to awareness within the community of structural engineers – by visiting some of the basic principles on which our profession holds on

CREATIVE PLACEMAKING: A CASE STUDY EXPLORATION OF HOW CREATIVE ECONOMY STRATEGIES CAN PROVIDE POTENTIAL OPPORTUNITIES FOR REVITALIZATION IN DOWNTOWN CHICOPEE, MA

Chicopee, a former industrial center in western Massachusetts, is experiencing a stagnant economy, high vacancy and a steady loss of population. City of Chicopee wants to increase downtown visibility and bolster its economy by attracting in the area people constituent of creative class. This research represents an attempt to identify creative strategies to develop the neglected downtown of Chicopee. After more than a century of economic blight, vacancy and declining population, the city wants to research and exploit the potential of arts and culture as means to a physical, social and economic revivification of its downtown. A key aim of this study is to formulate a set of best practices and recommendation based on relevant literature and case studies. These evaluations and recommendations would assists the city of Chicopee to craft policies, as they would find appropriate, to help increasing the downtown area economic performance and at large the city economic growth. The recommendations could also serve to the community groups, such as artists, entrepreneurs, students and young professional that want to join their forces to promote community values and redevelopment

The Relationship Between Academıc Self-Efficacy And Patience Tendencies Of Physıcal Education And Sports Teachers: The Case Of The Eastern Black Sea Regıon

The goal of the study is academic efficacy related to patience tendencies of teacher candidates of physical education. The research contained teacher candidates studying in sports science departments of state universities in the Eastern Black Sea region, and randomly selected 205 people as sample group. Socio-demographic form, self-efficacy and patience tendency scales were performed by participants. Statistical analysis was performed in computer environment. The arithmetic averages of the scores of sports science students from scales are reported. Spearman correlation analysis (r) was used. The results showed that while the academic self-efficacy levels of the participants were high, the total and sub-dimensions of the patience disposition were at an average level. Psitively low level of correlation was seen between continuous variables. When academic self-efficacy and the subdimensions of patience tendency were examined, a positively low correlation was found with patience against haste, and a moderate positive relationship with anger against anger was seen. It is thought that this situation is because of the participants’ in-faculty curriculum programs and the effects of the sports branch they are dealing with on their character development

Does an(y) order exist within the Structural Art

Many authors have treated the beauty and aesthetics from the social and phylosofic point of view [Kant, Plato], whereas very few of them have meditated within the domain of Architecture let alone Structural Engineering [Leonhardt]. The Beautiful is beautiful, and the Ugly is ugly, but subjectivity apart, is any mean of defining a way or some Principles which can be of Guide for the designer. Is there any mathematics within the beauty, i.e., can the beauty be described in a mathematical way. It is a simple, yet a very difficult question answering, since both the beauty and aesthetics falls into the domain of feelings, whereas each human doesn\u27t feel the same when seing an object created by an another human. This Paper is represents a modest temptation to prove that it can be done.

Passive control of structures

Lately, powerful earthquakes stroke some parts of the world, while the Balkan Peninsula was hit by moderate ones. During a powerful earthquake, a building structure is invaded by an enormous quantity of kinetic energy . As far as the manner is concerned, this energy it is initially absorbed, and thereafter distributed throughout building structure relying not only to the reaction of structure as a whole, or structural elements in particular, but the nature, the distribution and the quantity of the damages also. As Nikola Tesla once quoted:“If you want to find the secrets of universe, think in terms of energy, frequency and vibration”. In order to be able to achieve some degree of control, in structural engineering, the frequency is the fundamental parameter one must begin with. Passive control is actively implemented in the developed countries, whereas intensive laboratory examinations are underway the last two decades in the domain of semi-active and active structural control as well. Among others this paper will also tackle issues related to: the seismic isolation, which represents in itself an issue of significant importance

THE ASSESSMENT OF USING SUPPLEMENTARY MATERIALS IN THE PROCESS OF TEACHING ENGLISH IN HIGH SCHOOLS IN GJILAN

Nowadays, English has acquired the status of an international language. It has become an integral part of modern culture, economics, politics, sport, education, art, tourism, science and other fields. It should be noted, that oral and written communication in English became a reality and a necessity: people often encounter TV broadcasting, simple instructions for use in English, as well as communication with foreigners, both in life and on the Internet. Mastering communicative competence in English, not being in the country of the language being studied, is a very difficult matter. Therefore, an important task of the teacher is to create real and imagined situations of communication in the classroom of a foreign language, using different methods and techniques of work (role-plays, discussions, creative projects, and others). Equally important is the task of involving pupils in the cultural values of the people - the native speaker. For these purposes, the use of authentic materials (drawings, texts, sound recordings, etc.) is of great importance. In this paper, there were studied the innovative methods of teaching English language and supplementary materials, which are mostly used by teachers. By means of  a questionnaire for both, teachers and pupils, it was possible to get to know which materials are mostly used at English classes and why, and also, to conclude why this or that supplementary material is effective or ineffective.Keywords: supplementary materials, visualization, approaches, effectiveness, teaching process, methods and techniques