Logical structure analysis of scientific publications in mathematics

Even though the Linking Open Data cloud is constantly growing, there is a serious lack of published data sets related to the domain of academic mathematics. At the same time, since most scholarly publications in mathematics are well-structured and conventional, it's promising to get their helpful detailed representation. The paper describes an approach to extracting and analyzing the structure of mathematical papers. We present the Mocassin ontology that is used by analysis algorithms and can be considered as an ontology of the structure of scholarly publications in mathematics. The proposed semantic model has been evaluated on a set of real mathematical papers and preliminary evaluation results are encouraging. Also we discuss potential applications of the model to specific information retrieval tasks including semantic search. © 2011 ACM

Simulation of non-stationary gas dynamics of solid propellant rockets launch

The article presents the results of the development of methodology for the calculation of non-stationary gas dynamics processes occurring in gas dynamic paths of rocket engines and environment at the launch of rockets. The method takes into account the change of geometry of solid fuel combustion surface during the operation of the engine and the change in the geometry of the computational domain taking into account the dynamics of rocket launch. Numerical simulation of gas-dynamic processes of the launch of model solid-fuel rocket was done. The unsteady gas-dynamic flow pattern was investigated. The pressure curve in the solid propellant rocket engine combustion chamber, the speed of movement and overload were determined

Mathematical investigation of pressure pulsations characteristics and natural acoustic frequencies in the gas-dynamic channel

Paper presents a numerical simulation of the occurrence of flow instability and pressure self-oscillations for a complex configuration of the gas-dynamic tract in combustion chamber. Unsteady axisymmetric two-dimensional Navier-Stokes equations are used for mathematical modelling of compressible one-phase medium. To simulate turbulence, the k-ε and LES models were used. Fast Fourier Transform (FFT) determined the frequency spectrum of pressure pulsations in the combustion chamber. It is shown that in the case of a simple geometry of the free gas cavity in combustion chamber, both models of turbulence make it possible to determine the spectrum of the natural acoustic frequencies. Using the LES model in the case of complex geometry makes it possible to predict the hydrodynamic structure of a flow accurately. The flow, in this case, has an intensive vortex generation. Formation of small-scale vortex occurs in the near-wall regions and large eddies in the core of a flow. Frequency of large eddies formation can be combined with the natural acoustic frequencies of combustion chamber and can affect the amplitude of pressure pulsation

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

The universal algorithm for solving the gas dynamics equations on the mesh with arbitrary number of cell faces

The paper presents methodology and algorithm for calculating the equations of gas dynamics on arbitrary computational meshes with a mixed type of cells. The calculation method is based on the method of linear reconstruction proposed by Barth and Jesperson. The algorithm for determining the geometric parameters of arbitrary computational cell is presented. To implement the calculation algorithm, a data storage system has been proposed and tested. The algorithm of the solver and the algorithm of docking the computational meshes in the case of using block-structured meshes are proposed. The efficiency of methodology and developed program of calculation are demonstrated by the calculation example of the air flow in flat air intakes. The structure of flow and position of the bow shock wave are determined. These results with the theoretical values were compared. The application of the proposed methodology and calculation algorithm to arbitrary computational meshes with a mixed cell type makes it possible to optimize the process of constructing computational mesh and conduct numerical studies of gas dynamics in regions of complex geometry

Method of gas flows calculation in solid propellant rocket engines taking into account the combustion of solid fuel charge

The paper presents a method for calculating the local and integral characteristics of the flow in the axisymmetric gas-dynamic paths of solid propellant rocket motors, taking into account the combustion of a charge of solid fuel. The numerical method of calculation is based on the use of the Godunov scheme, formulated for moving computational grids. The speed of movement of the combustion surface is defined locally on the edge of each calculation boundary cell. This approach allows us to take into account the uneven distribution of the pressure of the combustion products in the free volume of the combustion chamber. In test calculations, the power law of burning rate is used. Calculations of the gas flow in the solid propellant combustion chamber with cylindrical charge of solid fuel are carried out. Unsteady pressure curve in the combustion chamber is obtained. The method allows to determine all integral characteristics of the developed solid propellant rocket motors as a function of the engine running tim

Разработка интеллектуальной системы оценки состояния беспилотного летательного аппарата на основе нейросетевых технологий

Nowadays, unmanned aerial vehicles (UAV) become more applicable right along. The growing demand for their use is stipulated by economic considerations, and also by a capability for fulfilling the high-risk tasks. One of the most important tasks arising, when developing the unmanned equipment, is to detect dangerous situations because of possible failure of the on-board systems. Presently, this problem is solved mostly by multiple redundancies. Through computer technology development, along with traditional approaches, data mining tools, in particular artificial neural networks become more commonly used. The use of neural network tools to analyse multi-dimensional data can reduce the redundancy level, as well as to solve a wide range of tasks in real time. The paper suggests a new approach, which uses the multidimensional data analysis based on the neural network models, to develop an integrated system for assessing the UAV state. This system is designed to solve a wide range of tasks, such as troubleshooting the on-board equipment based on the complex analysis of measurements, redundancy of faulty sensors, assessment of the aerial vehicle state, and hazard prediction and prevention. Also, this system allows troubleshooting in the control system and enables the capability to complete a maneuver by assuming the control. Another important task is to keep logging of measurements and assess the aerial vehicle state using the neural network forecasting models. An equally important task is to verify the reliability of the UAV model comparing with real flight data. This system allows us not only to determine a divergence between the model and the object, but also localise the error and produce recommendations for correction. The paper presents a solution to these problems based both on the simulation results and on the real flight data.В настоящее время сфера применения беспилотных летательных аппаратов (БЛА) непрерывно расширяется. Растущий спрос на них обусловлен экономическими соображениями, а также связан с возможностью выполнять задачи повышенного риска. Одной из важнейших задач, возникающих при создании беспилотной техники, является детектирование нештатных ситуаций, причиной которых может служить выход из строя бортовых систем. В настоящий момент времени данная проблема решается преимущественно многократным резервированием. Благодаря развитию вычислительной техники, наряду с традиционными подходами все большее применение находят средства интеллектуального анализа данных, в частности, – искусственные нейронные сети. Применение нейросетевых средств анализа многомерных данных может позволить сократить уровень резервирования, а также решать широкий круг разноплановых задач в режиме реального времени. В работе предложен новый подход к разработке комплексной системы оценки состояния БЛА, основанный на анализе многомерных данных с помощью нейросетевых моделей. Данная система предназначена для решения широкого круга задач, таких как детектирование неисправностей бортовой аппаратуры на основе комплексного анализа измерений, резервирование неисправных датчиков, оценка состояния летательного аппарата, прогнозирование и предотвращение опасных ситуаций. Также данная система позволяет определять неисправность системы управления и обеспечивает возможность завершить маневр, взяв управления на себя. Еще одной важной задачей является ведение журнала измерений и оценка состояния летательного аппарата с использованием нейросетевого прогнозирования. Не менее важной задачей является определение достоверности модели беспилотного летательного аппарата самолетного типа на основе его полетных данных. Данная система позволяет не только определять ее расхождение с объектом, но также локализовывать ошибку и вырабатывать рекомендации по корректировке. В работе предоставляется решение этих задач как на основе результатов моделирования, так и реальных полетных данных