bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies in SE Fennoscandian mires, with special regard to the use of multivariate techniques and the scaling of ecological gradients.
Authors: Økland R.H. 
Published: August 2021

Abstract
The study presents the results from an integrated approach to hydromorphology, species distribution, and ecological conditions in SE Fennoscandian bogs and poor fens. Patterns of distribution are observed on spatial scales ranging from 0.25 m2 to whole mires (1 km2), and the scope of the study extended to include the regional perspective. Detailed ecological studies studies are performed within a restricted part (0.3 km2) of one mire complex, N. Kisselbergmosen, R{lkienes, SE Norway, while the distribution of plant species and hydromorphological mire types is studied within parts (1000 km2) of Akershus and Østfold counties, SE Norway. Patterns are interpreted by use of multivariate techniques, in particular ordination by detrended correspondence analysis (DCA). On the scale of one mire, four complex-gradients are shown to account for most of the vegetational variation. The relative merits of different sampling procedures and classification systems are discussed. On a broader scale, gradient relationships of vegetation, hydromorphology and species distributions can mostly be ascribed to variation in thermal and hygric factors, often operating in conjunction. Their effects on the vegetation are often mediated by differential water supply. Structuring factors in boreal mires are discussed, and interspecfic interaction as well as abiotic factors are important. The importance of interactions is higher in the bottom layer in the field layer. On a fine scale, boreal mires are considered to conform to the patch dynamics theory of non-equilibrium coexistence of species. On a broad scale, boreal mires appear to be in a dynamic equilibrium with present climatic conditions east of the limit for the onset of erosion. The common conceptual basis for descriptive biogeography and vegetation ecology is emphasized. Arguments in favour of scaling ecological gradients in units of compositional turnover are forwarded, and the properties of one such scaling method, the nonlinear rescaling procedure in DCA ordination, is outlined. The advantage of an integrated approach to ecological problems is emphasized.
Nakit Akışlarının Sağlandığı Faaliyetler Modeli İle İşletmelerin Nakit Akış Profillerinin İncelenmesi: BİST 30, BİST 50 Ve BİST 100 Endeksleri Karşılaştırması
Authors: ÇİL KOÇYİĞİT Seyhan , GÜNGÖR TANÇ Şükran 
Published: August 2021

İşletmelerin sürdürülebilirliklerini sağlamaları için düzenli etkin bir nakit akış sistemi önemli bir husus olarak
görülmektedir. Başarılı işletmelerin nakit akış sistemlerinin de; işletme faaliyetleri, yatırım faaliyetleri ve finansman
faaliyetleri üzerindeki olumlu etkisi beklenmektedir. Bu bağlamda; çalışmanın temel amacı; 2020 yılında BIST 100
kapsamında yer alan bankacılık ve sigortacılık sektörü dışındaki işletmelerin geçmiş 5 yıllık (2015-2019 yıllarına ait) nakit
akış tablolarının “nakit akışlarının sağlandığı faaliyetler modeli” yöntemleri ile analiz edilerek, finansal sonuçların BIST 30,
BIST 50 ve BIST 100 endeksleri kapsamında karşılaştırılmasıdır. Araştırma sonucunda; her bir endeks kapsamındaki
işletmelerin çoğunlukla model 2 “olgun başarılı bir işletme” profiline sahip oldukları görülmüştür. BIST 30 kapsamındaki
işletmelerin araştırma kapsamındaki BIST 50 ve BIST 100’de yer alan işletmelere göre daha çok model 2 “olgun başarılı bir
işletme” profiline sahip oldukları tespit edilmiştir.
Bağımsız Denetçi Görüşlerinin Yatırım Kararları Açısından Önemi: Yeni Bir Kesitsel Anomali mi?
Authors: KARCIOĞLU Reşat , ÖZTÜRK Seyhan , YILMAZ Cihan 
Published: August 2021

Bağımsız denetim, piyasa etkinliğinin artmasında, özellikle finansal tabloların şeffaflığı ve şirketlerin mali
durumunun menfaat sahiplerince kıyaslanabilir bir şekilde anlaşılması açısından olmazsa olmaz bir unsur teşkil etmektedir.
Doğru yatırım kararlarının verilmesinde, bağımsız denetçi görüşlerinin ilgili taraflarca doğru biçimde analiz edilmesinin
önemli bir faktör olduğu değerlendirilmektedir. Bu çerçevede söz konusu çalışma; bağımsız denetçi görüşlerinin de yer aldığı
bağımsız denetim raporlarının kamuya açıklanması sonrasında şirketlerin hisse senedi fiyatlarındaki anormal fiyat
hareketlerinin var olup olmadığını ve bahsi geçen firmalara özgü anomalilere bir yenisinin daha eklenebilip
eklenemeyeceğini araştırmayı amaçlamaktadır. Bu amaç doğrultusunda; olumlu, olumsuz ve görüş bildirilmemiş olan
denetim raporlarına sahip şirketlerin 2019 ve 2020 yılına ait denetçi görüşlerinin yer aldığı altı aylık süreler içerisindeki
hisse senedi getirileri hesaplanarak, borsanın tamamını yansıtma özelliğinden hareketle BIST 100 endeksinin getirisi ile
karşılaştırılmış ve anormal bir getiri (endeksin üzerinde) elde edilip edilmediği tespit edilmeye çalışılmıştır. Öncül bulgulara
göre; Borsa İstanbul (BİST)’un söz konusu dönemler için yarı güçlü formda etkin olmadığı ve yatırımcıların şirketlerin
kamuya açıklanan bağımsız denetim raporlarında yer alan bağımsız denetçi görüşlerinin türüne göre yatırım pozisyonu
alarak endeksin üzerinde getiri elde etme olanağına sahip oldukları belirlenmiştir.
Modelling and numerical study of the physicochemical laws of 1,4-cis-polyisoprene obtained in the presence of modified catalytic systems
Authors: Мифтахов Эльдар Наилевич , Мустафина Светлана Анатольевна , Спивак Семен Израилевич 
Published: August 2021

Построена математическая модель, описывающая процесс получения полиизопрена в присутствии микрогетерогенных титансодержащих каталитических систем с учетом динамики активных центров. Построение модели носило поэтапный характер, при котором модель, описывающая периодический процесс, была дополнена рекуррентными соотношениями с целью описания процесса в каскаде реакторов идеального перемешивания. Численное решение прямой задачи позволило провести анализ молекулярно-массового распределения получаемого продукта в зависимости от исходной загрузки.
The aim of this work is building a mathematical model that describes the process of producing polyisoprene in the presence of microheterogeneous titanium-containing catalytic systems, taking into account the dynamics of active centers and numerical calculation of the main physicochemical properties of the resulting product. The main methodology for compiling the mathematical model is the application of the kinetic approach, which consists of compiling and numerically solving the kinetic equations for all types of particles involved in the process. Previously, the distribution of active centers of the applied catalytic system was studied. The confirmed polycentricity of the used catalyst, represented by two types of active centers, is reflected in the nature of the description of the mathematical model. To reduce the system of differential equations to the final form, the method of moments was applied, which allows evaluating the complex properties of the obtained product by its averaged molecular characteristics. A model that permits describing the scale of batch reactors was modified by a macrokinetic module that takes into account possible energy and hydrodynamic laws of the process. For this, recurrence relations were introduced that are valid for the description of continuous mixing reactors. The software package developed by the authors of the work allows carring out a computational experiment for various technological conditions for conducting a continuous process. Based on the results of its launch, the dependences of conversion and averaged molecular characteristics on time in the context of each polymerizer were obtained. Thus, the numerical solution of the direct problem is capable analyzing the molecular weight distribution of the obtained product depending on various parameters of the initial load, for both the batch and continuous modes of the process. The dependences obtained by calculation showed satisfactory agreement with experimental data
Stable algorithm of nonparametric identification in case of anomalous measurements
Authors: Воскобойников Юрий Евгеньевич , Боева Василиса Андреевна 
Published: August 2021

Математические модели многих технических систем имеют вид интегрального уравнения Вольтерра I рода с разностным ядром. Для таких систем задача идентификации заключается в построении оценки для импульсной переходной функции системы по измеренным (с шумами) значениям входного и выходного сигналов и является некорректно поставленной. В недавней работе авторов предложен устойчивый алгоритм идентификации, использующий аппарат сглаживающих кубических сплайнов для вычисления первых производных входного и выходного сигналов. К сожалению, сглаживающие кубические сплайны неудовлетворительно фильтруют аномальные измерения. Поэтому предложен двухшаговый алгоритм идентификации, на первом шаге которого аномальные измерения удаляются с использованием пространственно-локального фильтра, а затем строятся сглаживающие сплайны
Volterra integral equation of the first kind often represents stationary dynamic systems. For such a model, the non-parametric identification problem reduces to the estimation of pulse transition characteristics (that is the kernel of integral equation) from the registered noise-contaminated values of input and output signals. To formulate stable solution for identification problem authors propose algorithm that estimates pulse transition characteristics by solving Volterra integral equation of the second kind and involving first derivatives of input and output signals application that corresponds to non-stable problem. Smoothing cubic splines employed in robust calculation of first derivatives allow finding a stable solution of identification problem even when input and output signals of system identified are essentially noise-contaminated. Unfortunately, measured values of input and output signals also contain anomalous measurements such as pulse noises, glitches, etc. Such measurements are poorly smoothable by splines that cause high levels of first derivatives errors and, conversely, significant pulse transition characteristics identification errors of dynamic system. For all the reasons aforementioned, in this paper authors present the new stable two-step identification algorithm in case of anomalous measurements. The first step of the algorithm is for non-linear local-spatial combined filtration procedure of input and output signals that helps to effectively remove anomalous measurements. At the second step, smoothing cubic splines are used to calculate stable first derivatives of previously filtered signals. An extensive computational experiment showed the effectiveness of the proposed algorithm, which allows solving the identification problem with acceptable accuracy in practice even at high intensity of anomalous measurements. The experimental results give reason to recommend this algorithm for solving practical problems of identifying stationary systems, the mathematical model of which is the Voltaire integral equation of the first kind with a difference kernel
Improving the accuracy for numerical solutions of the Ginzburg - Landau equation
Authors: Паасонен Виктор Иванович , Федорук Михаил Петрович 
Published: August 2021

Решение актуальной задачи повышения порядка точности разностных методов решения задач нелинейной волоконной оптики выше четвертого путем непосредственного построения сложных схем на расширенных шаблонах сопряжено с усложнением матрицы системы и с затруднениями в постановке дополнительных граничных условий. Кроме того, при таком подходе не происходит одновременное повышение точности также и по эволюционной переменной. В данной работе рассматривается альтернативный путь - применение экстраполяции Ричардсона, которая сводится к построению подходящих линейных комбинаций решений на различных сетках. Этот способ позволяет повышать порядок точности по обеим переменным, избегая при этом проблем с усложнением шаблонов, постановкой дополнительных граничных условий и реализацией алгоритмов. Как средство дополнительного улучшения точности наряду с простыми (однократными) поправками исследуются также двойные поправки на основе экстраполяции Ричардсона. Методика протестирована на нескольких точных решениях уравнения Гинзбурга - Ландау
Increasing the order of accuracy for difference methods is an actual problem in nonlinear fiber optics. Computations, which use higher than the fourth order of accuracy by the direct construction of complex circuits on extended templates pose the complication of the system matrix and difficulties in setting additional boundary conditions. In addition, with this approach, there is no simultaneous increase in accuracy for the evolutionary variable. In this paper, we consider an alternative way, namely, application of the Richardson extrapolation, which reduces to construction of suitable linear combinations for solutions on various grids. This method allows improving the order of accuracy for both variables, while avoiding problems associated with the complication of templates, implementation of algorithms and setting additional boundary conditions. Double corrections are also considered to further improve accuracy. The technique was tested on exact solutions of the Ginzburg - Landau equation
Computable simulated transformations of the Cartesian coordinates for random vectors
Authors: Абдразакова Анжела Романовна , Войтишек Антон Вацлавович 
Published: August 2021

Рассмотрены специальные преобразования декартовых координат, позволяющие строить эффективные (экономичные) алгоритмы численного моделирования многомерных случайных величин. В качестве иллюстративных и практически значимых примеров таких преобразований рассмотрены переходы к полярным, сферическим, параболическим и цилиндрическим координатам.
The purpose of the paper was to expand the range of efficient (economical) computer algorithms for simulation of multi-dimensional random variables. The authors noticed that in a number of applied problems (for example, when modelling twoor three-dimensional isotropic vectors), transitions from Cartesian to other coordinate systems (for example, to polar or spherical) are effective. In this regard, the new generalizing notation of the computable simulated transformation of Cartesian coordinates is introduced in the paper. Such transformations allow constructing effective (economical) algorithms for the numerical modelling (simulation) of multi-dimensional random variables. The problem of finding examples of constructive and practical applications for computer simulated transformations of Cartesian coordinates is formulated. Transitions to polar, spherical, parabolic and cylindrical coordinates are considered as illustrative examples of such transformations. The practical applications of computable simulated transformations of Cartesian coordinates found in the scientific literature are described in detail by the authors. These applications are associated with both computer modelling (simulation) of isotropic vectors and Gaussian distribution along with the numerical solution of boundary value problems and problems of radiation transfer. Thus, the introduced notion of the computable simulated transformations of Cartesian coordinates is quite constructive. It opens up prospects for the scientific search for new transformations of this type with the aim of using them in stochastic computer models for important processes and phenomena.
Development of the LBM non-isothermal flows with arbitrarily large Mach number
Authors: Зипунова Елизавета Вячеславовна , Перепёлкина Анастасия Юрьевна , Закиров Андрей Владимирович 
Published: August 2021

При решении задач динамики жидкостей и газов в области малых скоростей потока и при изотермических условиях с успехом применяется метод решеточных уравнений Больцмана (LBM). Для решения дискретного уравнения Больцмана может быть использован новый метод Particles-on-Demand (PonD), в котором в каждой точке сетки дискретизация функции распределения в пространстве скоростей центрирована относительно текущей скорости потока. В отличие от классического LBM, метод PonD применим не только для задач с малыми скоростями потока и при изотермических условиях. В данной работе реализован метод PonD D1Q5 с итерационным расчетом скорости переноса и явным расчетом первых трех моментов, включая скорости переноса. Показано, что рассмотренная модификация метода PonD хоть и накладывает ограничения на параметры, позволяет проводить расчеты в большем диапазоне допустимых скоростей.
The purpose of the paper is to demonstrate applicability of the Particle on Demand (PonD) D1Q5 method with the explicit calculation of the first three moments to problem with high speed of the flow. The standard LBM is applicable for small flow velocities. Thus to overcome this limitation we use PonD. In this work, we use conservative version of PonD - the D1Q5 method with the explicit calculation of the first three moments. Methodology. The Pond over LBM was applied to the Riemann problem in order to demonstrate the advantage of the method. In this work, we choose the case when contact discontinuities could propagate at variable speed. Findings. If the interpolation pattern is fixed relative to the point at which there is a current update of the discrete distribution function, then the transfer step can be written explicitly, thus the scheme is conservative. On the other hand, this imposes additional restrictions on the temperature and the flow rate. But even if the PonD scheme is limited to a fixed interpolation pattern, it is possible to simulate flows with larger values of the Mach number than in the case when the classical method of lattice Boltzmann equations is used. Originality/value. In the described particular case of the PonD method, it is possible to avoid iterations by calculating the temperature and velocity values directly at a new time layer. In this work, we have investigated the properties and the range of applicability (admissible values of temperature and velocity) of such modification of PonD.
Group control complex for unmanned vehicles
Authors: Котов Константин Юрьевич , Мальцев Александр Сергеевич , Пришляк Елизавета Егоровна , Соболев Максим Андреевич 
Published: August 2021

Представлен стендовый комплекс, предназначенный для разработки, моделирования и экспериментальных исследований систем управления беспилотными аппаратами колесного, гусеничного и мультироторного типа. Рассмотрены алгоритмы и архитектура программного обеспечения комплекса, реализующего функции построения математических моделей динамики, определения пространственных координат и децентрализованного управления движением роботов в составе группы.
The purpose of this work is to develop the test bench for modelling and controlling a group of wheeled and multi-rotor unmanned vehicles. Such test bench should solve the problems of studying the control algorithms of individual robots and their groups which ensure the formation of a group of robots with a given orientation in space and automatically control their joint movement along the desired trajectory with preserving the spatial configuration. The solution is achieved using the proposed software and hardware architecture, which is a set of independent programs that exchange signals through the Redis shared data server or through the Robot Operating System. The result is the control system for group of mobile robots that includes the motion surface, the technical vision system, mathematical methods of motion control and specialized software. This test bench can reduce the costs associated with the development, implementation, and testing of unmanned vehicle control systems.
Critical comparison of the different versions of the OpenFOAM on the simulation of spillway
Authors: Курбаналиев Абдикерим Ырысбаевич , Ойчуева Бурулгул Рахманбердиевна , Калмурзаева Анипа Ташбаевна , Жайнаков Аманбек Жайнакович , Култаев Топчубай Чокоевич 
Published: August 2021

Приведены предварительные результаты численного моделирования двухфазного течения двух несжимаемых и несмешивающихся жидкостей через водослив трапециевидной формы. Целью работы была демонстрация возможностей решателя interFoam различных версий открытого пакета OpenFoam при моделировании рассматриваемого класса течений. Численные расчеты проведены с использованием входящего в состав OpenFoam руководства weirOverFlow. В пакете OpenFOAM6 коэффициент fvcDdtPhiCoeff для вычисления потоков массы на гранях ячеек изменен в целях улучшения устойчивости/точности и исключения осцилляций давления при высоких числах Куранта. Он вычисляется с использованием значений плотности и потока массы с предыдущего временн´ого шага. Результаты численных расчетов показывают, что такие изменения вызывают чрезмерно быстрый переход от нестационарного течения к стационарному.
The results of numerical simulation for a two-phase flow of two incompressible and immiscible liquids through a trapezoidal spillway are presented. To simulate the free boundary, we used the method of fluid volume. The aim of the work was to demonstrate the capabilities of the various versions of interFoam solver of the OpenFOAM package for modelling the considered class of flows. Numerical calculations were performed using the OpenFOAM weirOverFlow tutorial. In order to improve the consistency, usability, flexibility and ease of modifying the interFoam solver, the existing interDyMFoam solver with the local dynamic mesh adaptation function was combined with the interFoam solver with a static computational mesh. In addition, in the OpenFOAM6 package, the fvcDdtPhiCoeff coefficient used for calculating the time derivative and taking into account the Rhie- Chow correction on the collocated grid for calculating mass fluxes on the cell faces was changed in order to improve stability/accuracy and eliminate pressure oscillations at high Courant numbers. The calculation of fvcDdtPhiCoeff coefficient in OpenFOAM5 requires the density value from the current time step along with the mass flow value from the previous time step, while in OpenFOAM6, both density and mass flow values are taken from the previous time step for calculation of the fvcDdtPhiCoeff coefficient. The results of numerical calculations of the OpenFOAM6 package show that such changes lead to an excessively fast transition of the transient flow to the stationary one in comparison with other versions of the OpenFOAM package.