Stability of retrial queueing system with constant retrial rate

We study the stability of a single-server retrial queueing system with constant retrial rate and general input and service processes. In such system the external (primary) arrivals follow a renewal input with rate $\lambda$. The system also has service times with rate $\mu$. If a new customer finds all servers busy and the buffer full, it joins an infinite-capacity virtual buffer (or \textit{orbit}). An orbital (secondary) customer attempts to rejoin the primary queue after an exponentially distributed time with rate $\mu_0$

Proper names in the work "David Copperfield" by Charles Dickens

A proper name is of great importance in culture and human life. According to a number of philosophers, there is a close connection between the name of the person and the events that happen in his life. In the literature names are not less important than images. In any text proper names are chosen by the author not casually. In the works by Ch. Dickens the proper names are an integral part of the characters' images. The author named the heroes after careful consideration. In this article a special attention is paid to the analysis of the proper names used in his novel «David Copperfield» and on the basis of the received results the conclusion about the role of the proper names in the text is drawn. Имя собственное имеет большое значение в культуре и жизни человека. По мнению ряда философов, между именем человека и событиями его жизни существует тесная связь. В художественном тексте имена не менее необходимы, чем сами образы. Для любого художественного текста характерна не случайность употребления автором имен собственных. В произведениях Ч. Диккенса имена собственные являются неотъемлемой частью образов действующих лиц. В данной статье уделяется особое внимание анализу употребления имен собственных в произведении «Жизнь Дэвида Копперфильда, рассказанная им самим»; на основе полученных результатов делается вывод о роли имен собственных в художественном тексте

On the ergodicity bounds for a constant retrial rate queueing model

We consider a Markovian single-server retrial queueing system with a constant retrial rate. Conditions of null ergodicity and exponential ergodicity for the correspondent process, as well as bounds on the rate of convergence are obtained

Stability of constant retrial rate systems with NBU input*

We study the stability of a single-server retrial queueing system with constant retrial rate, general input and service processes. First, we present a review of some relevant recent results related to the stability criteria of similar systems. Sufficient stability conditions were obtained by Avrachenkov and Morozov (2014), which hold for a rather general retrial system. However, only in the case of Poisson input is an explicit expression provided; otherwise one has to rely on simulation. On the other hand, the stability criteria derived by Lillo (1996) can be easily computed but only hold for the case of exponential service times. We present new sufficient stability conditions, which are less tight than the ones obtained by Avrachenkov and Morozov (2010), but have an analytical expression under rather general assumptions. A key assumption is that interarrival times belongs to the class of new better than used (NBU) distributions. We illustrate the accuracy of the condition based on this assumption (in comparison with known conditions when possible) for a number of non-exponential distributions

Experimental study of multimodal perception of verbal stimuli in the study of a foreign language

Modern education, as well as communication, is inherently multimodal. Learning any foreign language requires the involvement of several perceptual channels in education. The article reports on a study of multimodal perception of verbal stimuli that exist with regard to conflict modalities. The study of particularities of a language is an important part of learning it as a foreign or second language. The author reports the results of an experimental study (on Bulgarian) which was aimed at identifying the dependence of the characteristics of bimodal (audio-visual) perception on the type of verbal stimuli categories incorporated: formal or semantic

Rare Color Variants in Lacertidae on the Example of Zootoca vivipara (Jacquin, 1787) in Ukraine

We used GIS modeling (DIVA-GIS, Maxent) to simulate the potential distribution of Zootoca  vivipara. For modeling, we used a database including information from our studies and literature, comprising 190 points of lizard samples (including 7 points for melanistic lizards). It can be concluded that the distribution of Z.  vivipara  in Ukraine depends on the following environmental variables related to solar radiation and precipitation: “Radiation of wettest quarter” (BIO24; 34.2%), “Precipitation of driest week” (BIO14; 18.1%), “Lowest weekly radiation” (BIO22; 15.7%) and “Mean diurnal temperature range” (BIO2; 12.8%). For habitats where melanistic lizards were found, “Mean moisture index of coldest quarter” (BIO35; 18.9%) was also significant in addition to BIO24 (50.4%) and BIO22 (17.3%)

Corporate Culture and Public Relations

Analyzing American publications dealing with the concept of excellent public relations, the authors trace the development of organizational culture and its connection with societal culture, as well as an alyze theoretical and methodological issues of corporate culture and its impact on public relations in an organization. Special attention is paid to some ways in which professional PR departments can be come the source of progressive counter cultures inside the organization capable of changing a prevailing culture in the organization to make it more excellent