Simulation Modeling of HM-Queueing Network With Limited Wait Time of Messages in Queueing Systems

The Markov queueing networks with incomes, with limit wait of messages in the queue is considering. Such networks can serve as stochastic models of estimation and prediction of incomes of different objects. The algorithm of construction of simulation model of network with limit wait of messages is reduced

Asymptotic Analysis Of Markov Queueing Network With Unreliable Systems

The closed exponentional queueing network with unreliable systems with the large number of messages is investigated. We have received the systems of differential equations for average number of messages and serviceable channels of network systems

To realisation of chromatic polynomial calculation algorithm

We calculate chromatic polynomial of an undirected graph using the fundamental reduction theorem and reducing to complete graphs. We also find the chromatic number using the chromatic polynomial. The C++ program was created, the result is obtained in the form of falling factorials and afterwards by the powers of x, the applications of chromatic polynomial are given

Specific hotel services: Belarus in the context of world experience

In the article the peculiar services provided by hotels are studied. The author dwells on the world experience, presents detailed examples of unusual services provided by different hotels to attract visitors and make their stay as comfortable as possible. Belarus experience is examined in the context of the world practice. The scientific significance of the findings is defined by the recommendations given by the author

Some problems of biotechnology for growing of larvae of giant freshwater prawn <i>Macrobrachium rosenbergii </i>(Decapoda: Palaemonidae)

Giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879) is cultivated in Crimea since 2000 and technology of complete cycle of its cultivation from planting material to saleable product is successfully applied nowadays. This area is located beyond of the species native habitat and has other environments, so the larvae and juveniles can harvested in controlled conditions only: the open water bodies with the water temperature above 20оC are recommended. Growing of the larvae in artificial conditions is the most difficult stage of the biotechnological process, with high mortality because of diseases, grazing by planktophages, and poor water quality. These factors were studied in conditions of spawn farm in 2001-2013 and the main reasons of the prawn mortality at the larval stage were revealed. They were the gas-bubble disease, low oxygen content in tanks, and penetration of predatory hydromedusae Sarsia tubulosa to tanks. All these problems were caused by failures in the cultivation technology. Measures for prevention of the prawn larvae disease because of external factors are proposed

Fecundity of the giant freshwater prawn <i>Macrobrachium rosenbergii</i> (Decapoda: Palaemonidae) in conditions of aquaculture

Giant freshwater prawn Macrobrahium rosenbergii is one of the most prospective species of Decapoda for artificial reproduction. It is cultivated mostly in the areas with subtropical and moderate climate, but rare is grown to the maximal size. Investigations for improvement the biotechnological process of this species cultivation were conducted in Crimea in 2010-2013, in particular for the stage of early ontogenesis. In total, 245 individuals were used in the experiments. The embryonic development was divided into 5 stages. The eggs were taken from pleopods of vital females and observed by microscope with measurements by ocular micrometer and weighting. Initial realized fecundity (IRF) and finite realized fecundity (FRF) were determined by the weight method. IRF for the females with length 7.7-14.3 cm and weight 5.2-38.4 g was 3071-54692 eggs in one clutch; FRF for the females with length 7.5-14.2 cm and weight 5.3-38.1 g was 678-39925 eggs in one clutch. Both IRF and FRF increased with the length and weight of females increasing. During embryonic development, the eggs grew in 1.5 times in size and 2.1 times in weight. The volume of the eggs ovulated and just laid to pleopods was 0.08 mm3 under the temperature 24оC and 0.06 mm3 under the temperature 28оC

Specific hotel services: Belarus in the context of world experience

In the article the peculiar services provided by hotels are studied. The author dwells on the world experience, presents detailed examples of unusual services provided by different hotels to attract visitors and make their stay as comfortable as possible. Belarus experience is examined in the context of the world practice. The scientific significance of the findings is defined by the recommendations given by the author

Дослідження впливу режимів електронно-променевої безтигельної зонної плавки металургійного кремнію на рафінування та структуроутворення зливків

The paper presents the results of studies obtained with the development of the technology of electron-beam crucible impregnation of metallurgical silicon. It is shown that refining of silicon from background and dopant impurities in electron-beam crucible-free zone melting occurs by zone purification during melting and as a result of evaporation of impurities from the sample surface.&nbsp; The mathematical model and computational experiment were been performed to determine the temperature gradient at different rates of zone melting. It was found the diapason of temperature gradients, which provides the columnar structure of crystallites and the purification of the samplesdue the melting with the zone recrystallization procedure. The level of the resistivity of the ingots increases at the end.У роботі представлені результати досліджень, які отримані при розробці технології електронно-променевої безтигельної зонної плавки металургійного кремнію. Показано, що рафінування кремнію від фонових і легуючих домішок при електронно-променевій безтигельній зонній плавці відбувається шляхом зонного очищення при плавці і в результаті випаровування домішок з поверхні зразка. Створено математичну модель і проведено обчислювальний експеримент, за допомогою якого визначено температурний градієнт при різних швидкостях зонного плавлення. Встановлено межі температурних градієнтів, при яких в процесі плавки формується стовпчаста структура кристалітів, що забезпечує разом з очищенням зразків в результаті зонної перекристалізації підвищення рівня питомого електроопору зливків