The dependence of the thermal characteristics of TVS-diodes during the passage of the pulse overload has been studied. The time dependences of the pulse voltage limitation and current are analyzed. Based on the analysis of the dependences, the thermal characteristics of the TVS-diode are calculated. It is shown that the parameters of the TVS-diodes deteriorate on reaching a current density of 160–300 A/cm2 and critical temperature of 250–300°С. The dependences of the thermal resistance and critical temperature of the TVS-diodes on the current density and the pulse duration are presented.
A synthesis method for the reference trajectory of an unmanned aerial vehicle that flies around obstacles of urban buildings in the horizontal and vertical planes is proposed. To solve this problem, for the first time a conformal mapping is constructed for a collection of rectangles that approximate the obstacles on the digital map of a terrain.
Статья посвящена описанию комплексного метода снятия частеречной омонимии в текстах на русском языке. Метод основывается на данных о синтаксической сочетаемости русских слов. В статье обсуждается метод сбора подобных корпусов.
Разработан новый метод измерения частоты основного тона повышенной помехоустойчивости. Проблема защиты от интенсивного фонового шума решена в нем путем частотной селекции вокализованных отрезков речевого сигнала по схеме c гребенчатым фильтром межпериодного накопления. Эффективность метода исследована теоретически и экспериментально с использованием разработанного многоканального частотного измерителя для акустического анализа речи. Показано, что при отношении сигнал-шум 10 дБ и выше погрешность метода в относительном выражении не превышает 2%.
Background: We present a method for reclassifying external causes of death categorized as “event of undetermined intent” (EUIs) into non-transport accidents, suicides, or homicides. In nations like Russia and the UK the absolute number of EUIs is large, the EUI death rate is high, or EUIs comprise a non-trivial proportion of all deaths due to external causes. Overuse of this category may result in (1) substantially underestimating the mortality rate of deaths due to specific external causes and (2) threats to the validity of studies of the patterns and causes of external deaths and of evaluations of the impact of interventions meant to reduce them.
Methods: We employ available characteristics about the deceased and the event to estimate the most likely cause of death using multinomial logistic regression. We use the set of known non-transport accidents, suicides, and homicides to calculate an mlogit-based linear score and an estimated classification probability (ECP). This ECP is applied to EUIs, with varying levels of minimal classification probability. We also present an optional second step that employs a population-level adjustment to reclassify deaths that remain undetermined (the proportion of which varies based on the minimal classification probability). We illustrate our method by applying it to Russia. Between 2000 and 2011, 521,000 Russian deaths (15 % percent of all deaths from external causes) were categorized as EUIs. We used data from anonymized micro-data on the ~3 million deaths from external causes. Our reclassification model used 10 decedent and event characteristics from the computerized death records.
Results: Results show that during this period about 14 % of non-transport accidents, 13 % of suicides, and 33 % of homicides were officially categorized as EUIs. Our findings also suggest that 2011 levels of non-transport accidents and suicides would have been about 24 % higher and of homicide about 82 % higher than that reported by official vital statistics data.
Conclusions: Overuse of the external cause of death classification “event of undetermined intent” may indicate questionable quality of mortality data on external causes of death. This can have wide-ranging implications for families, medical professionals, the justice system, researchers, and policymakers. With our classification probability set as equal to or higher than 0.75, we were able to reclassify about two-thirds of EUI deaths in our sample. Our optional additional step allowed us to redistribute the remaining unclassified EUIs. Our method can be applied to data from any nation or sub-national population in which the EUI category is employed.
We consider interior and exterior initial boundary value problems for the three-dimensional wave (d’Alembert) equation. First, we reduce a given problem to an equivalent operator equation with respect to unknown sources deﬁned only at the boundary of the original domain. In doing so, the Huygens’ principle enables us to obtain the operator equation in a form that involves only ﬁnite and non-increasing pre-history of the solution in time. Next, we discretize the resulting boundary equation and solve it eﬃciently by the method of difference potentials (MDP). The overall numerical algorithm handles boundaries of general shape using regular structured grids with no deterioration of accuracy. For long simulation times it offers sub-linear complexity with respect to the grid dimension, i.e., is asymptotically cheaper than the cost of a typical explicit scheme. In addition, our algorithm allows one to share the computational cost between multiple similar problems. On multi- processor (multi-core) platforms, it beneﬁts from what can be considered an effective parallelization in time.
The problem of measuring the temperatures of the radio-electrical components of printed circuits is investigated. A temperature measuring sensor (thermocouple) and possible errors are considered. A systematic error compensation method is proposed to ensure the necessary accuracy of measurements made with the temperature sensor. © 2015 Springer Science+Business Media New York
The independent set problem for a given simple graph is to determine the size of a maximal set of its pairwise non-adjacent vertices. We propose a new way of graph reduction leading to a new proof of the NP-completeness of the independent set problem in the class of planar graphs and to the proof of NPcompleteness of this problem in the class of planar graphs having only triangular internal facets of maximal vertex degree 18
This paper introduces a systematic technology trend monitoring (TTM) methodology based on an analysis of bibliometric data. Among the key premises for developing a methodology are: (1) the increasing number of data sources addressing different phases of the STI development, and thus requiring a more holistic and integrated analysis; (2) the need for more customized clustering approaches particularly for the purpose of identifying trends; and (3) augmenting the policy impact of trends through gathering future-oriented intelligence on emerging developments and potential disruptive changes. Thus, the TTM methodology developed combines and jointly analyzes different datasets to gain intelligence to cover different phases of the technological evolution starting from the ‘emergence’ of a technology towards ‘supporting’ and ‘solution’ applications and more ‘practical’ business and market-oriented uses. Furthermore, the study presents a new algorithm for data clustering in order to overcome the weaknesses of readily available clusterization tools for the purpose of identifying technology trends. The present study places the TTM activities into a wider policy context to make use of the outcomes for the purpose of Science, Technology and Innovation policy formulation, and R&D strategy making processes. The methodology developed is demonstrated in the domain of “semantic technologies”.
In this paper we consider the NP-hard 1|rj|ΣTj scheduling problem, suggesting a polynomial algorithm to find its approximate solution with the guaranteed absolute error. The algorithm employs a metric introduced in the parameter space. In addition, we study the possible application of such an approach to other scheduling problems.
What happens with Russian mathematics in terms of metric parameters? Where do Russian mathematicians work, where do they publish, how well are they cited?
For a semigroup $S(t):X\to X$ acting on a metric space $(X,\dist)$, we give a notion of global attractor based only on the minimality with respect to the attraction property. Such an attractor is shown to be invariant whenever $S(t)$ is asymptotically closed. As a byproduct, we generalize earlier results on the existence of global attractors in the classical sense.
Over the last decade, the Russian education system has undergone significant transformation that has radically changed the expectations placed upon the school principals. This current reform process has placed far greater responsibilities and accountabilities upon principals to secure school effectiveness and improved student learning outcomes. This article offers some insights into the way in which principals in Russia are currently prepared and trained. It outlines initial quantitative findings from Russian principals, as part of a contemporary, large-scale empirical study of principal leadership preparation and training. The emerging empirical evidence highlights that the new principal standards and training requirements in Russia reinforce ‘managerial approaches’ that are not necessarily meeting the needs of principals.
 7System Leadership Study (7SLS)
We consider a linear optimal control model for the marketing of seasonal products which are produced by the same firm and sold by retailers in different market segments. The horizon is divided in two consecutive non-intersecting intervals, called production and selling periods, respectively. The production period state variables are the inventory levels and two kinds of goodwills (consumers' and retailers' goodwill, respectively) while the selling period state variables are the sales levels and the two kinds of goodwiIls. ln the production interval there are three kinds of controls: on production, quality and advertising, while in the selling one the controls are on communication via advertisirng; promotion addressed to consumers and incentives given to retailers. We consider the case of several kinds of communications. The optimal control problem is transformed into an equivalent nonlinear programming problem.