Using the Monte Carlo simulation, we study the percolation and jamming of oriented linear kmers on a square lattice that contains defects. The point defects with a concentration, d, are placed randomly and uniformly on the substrate before deposition of the k-mers. The general case of unequal probabilities for orientation of depositing of k-mers along different directions of the lattice is analyzed. Two different relaxation models of deposition that preserve the predetermined order parameter s are used. In the relaxation random sequential adsorption (RRSA) model, the deposition of k-mers is distributed over different sites on the substrate. In the single cluster relaxation (RSC) model, the single cluster grows by the random accumulation of k-mers on the boundary of the cluster (Eden-like model). For both models, a suppression of growth of the infinite (percolation) cluster at some critical concentration of defects dc is observed. In the zero defect lattices, the jamming concentration pj (RRSA model) and the density of single clusters ps (RSC model) decrease with increasing length k-mers and with a decrease in the order parameter. For the RRSA model, the value of dc decreases for short k-mers (k < 16) as the value of s increases. For k = 16 and 32, the value of dc is almost independent of s. Moreover, for short k-mers, the percolation threshold is almost insensitive to the defect concentration for all values of s. For the RSC model, the growth of clusters with ellipse-like shapes is observed for non-zero values of s. The density of the clusters ps at the critical concentration of defects dc depends in a complex manner on the values of s and k. An interesting finding for disordered systems (s = 0) is that the value of ps tends towards zero in the limits of the very long k-mers, k → ∞ and very small critical concentrations dc → 0. In this case, the introduction of defects results in a suppression of k-mer stacking and in the formation of 'empty' or loose clusters with very low density. On the other hand, denser clusters are formed for ordered systems with ps ≈ 0.065 at s = 0.5 and ps ≈ 0.38 at s = 1.0.
Using the Monte Carlo simulation, we study the percolation and jamming of oriented linear k-mers on a square lattice that contains defects. The point defects with a concentration, d, are placed randomly and uniformly on the substrate before deposition of the k-mers. The general case of unequal probabilities for orientation of depositing of k-mers along different directions of the lattice is analyzed. Two different relaxation models of deposition that preserve the predetermined order parameter s are used. In the relaxation random sequential adsorption (RRSA) model, the deposition of k-mers is distributed over different sites on the substrate. In the single cluster relaxation (RSC) model, the single cluster grows by the random accumulation of k-mers on the boundary of the cluster (Eden-like model). For both models, a suppression of growth of the infinite (percolation) cluster at some critical concentration of defects dc is observed. In the zero defect lattices, the jamming concentration pj (RRSA model) and the density of single clusters ps (RSC model) decrease with increasing length k-mers and with a decrease in the order parameter. For the RRSA model, the value of dc decreases for short k-mers (k < 16) as the value of s increases. For k = 16 and 32, the value of dc is almost independent of s. Moreover, for short k-mers, the percolation threshold is almost insensitive to the defect concentration for all values of s. For the RSC model, the growth of clusters with ellipse-like shapes is observed for non-zero values of s. The density of the clusters ps at the critical concentration of defects dc depends in a complex manner on the values of s and k. An interesting finding for disordered systems (s = 0) is that the value of ps tends towards zero in the limits of the very long k-mers, k → ∞ and very small critical concentrations dc → 0. In this case, the introduction of defects results in a suppression of k-mer stacking and in the formation of 'empty' or loose clusters with very low density. On the other hand, denser clusters are formed for ordered systems with ps ≈ 0.065 at s = 0.5 and ps ≈ 0.38 at s = 1.0.
Тарасевич Юрий Юрьевич - доктор физико-математических наук, профессор, заведующий лабораторией «Математическое моделирование и информационные технологии в науке и образовании» Астраханского государственного университета. E-mail: tarasevich@asu.edu.ruШиняева Таисия Сергеевна - аспирант, младший научный сотрудник лаборатории «Математическое моделирование и информационные технологии в науке и образовании» Астраханского государственного университета. E-mail: danilova.taisiya@gmail.comАдрес: г. Астрахань, 414056, ул. Татищева, 20а.Обсуждаются критерии оценки эффективности научных исследований. Анализируется выполнимость задачи разработать научно обоснованные методы, которые позволят оценить деятельность научных направлений и научных коллективов. С точки зрения авторов, основой для проведения полномасштабных исследований динамики развития научных направлений и научных коллективов должны служить информационные системы текущих исследований (Current Research Information Systems, CRIS) организаций, интегрированные в национальную CRIS. Авторы предлагают методику оценки результативности текущих научных исследований, основанную на анализе престижа журналов, в которых опубликованы результаты исследований научного коллектива.
Ïðîâåäåí àíàëèç èíôîðìàöèè èç áàçû äàííûõ Scopus î âðåìåíí îé çàâèñèìîñòè èíäåêñà Õèðøà (h-èíäåêñà) è åãî ìîäèôèêàöèè h s (2015)-èíäåêñà ãðóïïû ïðîäîëaeè-òåëüíî è ñòàáèëüíî ðàáîòàþùèõ ó÷åíûõ. Îáíàðóaeåíî, ÷òî õàðàêòåð èçìåíåíèÿ ñî âðå-ìåíåì h s (2015)-èíäåêñà áëèçîê ê ñèãìîèäàëüíîìó. Ïðåäëîaeåíà ìîäåëü, îïèñûâàþùàÿ äèíàìèêó èíäåêñà Õèðøà. Ìîäåëü ó÷èòûâàåò: 1) èçìåíåíèå ïóáëèêàöèîííîé àêòèâ-íîñòè ó÷åíîãî ïðåäïîëàãàåòñÿ ñèãìîèäàëüíûé ðîñò ÷èñëà ïóáëèêàöèé íà íà÷àëüíîé ñòàäèè íàó÷íîé êàðüåðû; 2) ðàñïðåäåëåíèå ñòàòåé ïî ÷èñëó öèòèðîâàíèé; 3) äèíàìèêó öèòèðîâàíèÿ êàaeäîé êîíêðåòíîé ñòàòüè (ïðèíÿòî âî âíèìàíèå, ÷òî â òèïè÷íîì ñëó÷àå ÷èñëî öèòèðîâàíèé ñíà÷àëà âîçðàñòàåò, à çàòåì ïëàâíî óáûâàåò). Èññëåäîâàíà äèíà-ìèêà èíäåêñà Õèðøà â çàâèñèìîñòè îò ñðåäíåé ïðîäóêòèâíîñòè (÷èñëà ïóáëèêóåìûõ â òå÷åíèå ãîäà ñòàòåé). Èñïîëüçîâàíû äâà âèäà ðàñïðåäåëåíèÿ ÷èñëà ñòàòåé ïî ÷èñëó öèòèðîâàíèé: ðàñïðåäåëåíèå Ëîòêè è ãåîìåòðè÷åñêîå ðàñïðåäåëåíèå. Îáà ìîäåëüíûõ ðàñïðåäåëåíèÿ ïðèâîäÿò ê êà÷åñòâåííî âåðíîé âðåìåíí îé äèíàìèêå èíäåêñà Õèðøà. Èíäåêñ Õèðøà ó÷åíîãî ìåíÿåòñÿ ñî âðåìåíåì. Õèðø ïðåäïîëîaeèë, ÷òî h-èíäåêñ ñ ãîäàìè ðàñòåò ïðèáëèçèòåëüíî ëèíåéíî [1]. Ýòî ïðåäïîëîaeåíèå áûëî ïîäòâåðaeäåíî â ðàìêàõ ñòîõàñòè÷åñêîé ìîäåëè [5]. Îäíàêî, èññëåäîâàíèÿ íàóêîìåòðè÷åñêèõ äàí-íûõ ñâèäåòåëüñòâóþò, ÷òî ëèíåéíûé ðîñò h-èíäåêñà òîëüêî îäíà èç âîçìîaeíîñòåé åãî âðåìåíí îé äèíàìèêè [6,7]. Ëèíåéíûé ðîñò ìîaeåò çàìåäëÿòüñÿ âïëîòü äî âûõî-äà h-èíäåêñà íà ïîñòîÿííîå çíà÷åíèå; âîçìîaeíî è áîëåå ñëîaeíîå ïîâåäåíèå [6].  ðàìêàõ êîíöåïöèè ïðîöåññà ïðîèçâîäñòâà èíôîðìàöèè áûëî ïîêàçàíî, ÷òî h = T 1/α , ãäå T ïîëíîå ÷èñëî èñòî÷íèêîâ (ïóáëèêàöèé), α ïîêàçàòåëü Ëîòêè [8].  [9,10] áûëà ïðåäëîaeåíà ìîäåëü, â êîòîðîé ðîñò h-èíäåêñà ñ òå÷åíèåì âðåìåíè çàìåäëÿ-åòñÿ, è h-èíäåêñ âûõîäèò íà ïîñòîÿííîå çíà÷åíèå.  [11] ïðîâåäåíî êîìïüþòåðíîå ìîäåëèðîâàíèå äèíàìèêè èçìåíåíèÿ h-èíäåêñà ñî âðåìåíåì äëÿ ðàçëè÷íûõ ìîäåëåé ðàñïðåäåëåíèÿ öèòèðîâàíèé.  áîëüøèíñòâå ñëó÷àåâ ìîäåëü ïðîäåìîíñòðèðîâàëà ëè-íåéíûé ðîñò ñî âðåìåíåì h-èíäåêñà, â ðåäêèõ ñëó÷àÿõ íàáëþäàëîñü çàìåäëåíèå ðîñòà h-èíäåêñà.Ðàçíîîáðàçíûé õàðàêòåð çàâèñèìîñòè h-èíäåêñà îò âðåìåíè [6,7] çàñòàâëÿåò çà-äóìàòüñÿ î äâóõ âîçìîaeíûõ àëüòåðíàòèâàõ.• Óíèâåðñàëüíîå ïîâåäåíèå h-èíäåêñà îò âðåìåíè îòñóòñòâóåò. Äëÿ êàaeäîãî ó÷å-íîãî äèíàìèêà h-èíäåêñà óíèêàëüíà.
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