Evaluation of topic-based adaptation and student modeling in QuizGuide

This paper presents an in-depth analysis of a nonconventional topic-based personalization approach for adaptive educational systems (AES) that we have explored for a number of years in the context of university programming courses. With this approach both student modeling and adaptation are based on coarse-grained knowledge units that we called topics. Our motivation for the topic-based personalization was to enhance AES transparency for both teachers and students by utilizing typical topic-based course structures as the foundation for designing all aspects of an AES from the domain model to the end-user interface. We illustrate the details of the topic-based personalization technology, with the help of the Web-based educational service QuizGuide—the first system to implement it. QuizGuide applies the topic-based personalization to guide students to the right learning material in the context of an undergraduate C programming course. While having a number of architectural and practical advantages, the suggested coarse-grained personalization approach deviates from the common practices toward knowledge modeling in AES. Therefore, we believe that several aspects of QuizGuide required a detailed evaluation—from modeling accuracy to the effectiveness of adaptation. The paper discusses how this new student modeling approach can be evaluated, and presents our attempts to evaluate it from multiple different prospects. The evaluation of QuizGuide across several consecutive semesters demonstrates that, although topics do not always support precise user modeling, they can provide a basis for successful personalization in AESs

Coherence maps application for InSAR data accuracy improving

В работе представлен анализ методов применения карт когерентности для обработки интерферометрических пар изображений радиолокаторов с синтезированной апертурой (РСА). Экспериментально определены размеры окон усреднений, допустимых для решения практических задач. Представлен метод повышения точности цифровых моделей рельефа и карт подвижек рельефа, получаемых при интерферометрической съемке, основанный на маскировании карты когерентности. Показано повышение точности результата по сравнению с классической методикой.The paper presents the analysis of coherence maps application methods for the interferometric SAR images processing. The interferometric coherence is an important indicator of the reliability of the interferograms obtained by the interferometric synthetic aperture radar (InSAR), since the areas with low coherence values are unsuitable for processing the interferometric data. In addition, the coherence is used as a parameter of adaptive phase noise filters, and it can also be used for surface segmentation. The sizes of the averaging windows suitable for the solution of practical problems are experimentally determined. The method of accuracy increasing for the digital elevation maps and displacement maps obtained by InSAR systems based on masking the coherence map is presented. The DEM accuracy improvement in comparison with the classical estimation method is presented

Phase noise suppression in interferometric radar data using goldstein noise filtration

The article is devoted the coherence maps utilization for the phase noise filtration using the Goldstein filter for interferometric synthesized aperture radar (InSAR) images. For the ALOS PALSAR data (FBS imaging mode), four coherence estimation techniques (classical, difference slope compensation, Fourier slope compensation, and «peak-Fourier») were researched as the Goldstein filter parameter. The filtered interferograms were compared with the reference ground control points reprojected into the radar coordinate system. It is shown that the coherence estimation method affects the quality of the phase noise suppression. © 2020 American Institute of Physics Inc.. All rights reserved.This work was supported by the Center of Excellence "Geoinformation technologies and geophysical data complex interpretation" of the Ural Federal University Program (Act 211 Government of the Russian Federation, contract N 02.A03.21.0006)

Enriching Intelligent Textbooks with Interactivity: When Smart Content Allocation Goes Wrong

One of the main directions of increasing the educational value of a digital textbook is its enrichment with interactive content. Such content can come from outside the textbooks - from multiple existing repositories of educational resources. However, finding the right place for such external resources is not always a trivial task. There exist multiple sources of potential problems: from mismatching metadata to mutually contradicting prerequisite-outcome structures of underlying resources, from differences in granularity and coverage to ontological conflicts. In this paper, we make an attempt to categorize these problems and give examples from our recent experiment on automated assignment of smart interactive learning content to the chapters of an intelligent textbook in a programming domain

The problem of quality assessing for the methods of coherence maps calculation in InSAR remote sensing of the Earth data processing

Interferometric coherence is an important indicator of the quality of interferograms obtained by synthetic aperture interferometric radars (InSAR), because the areas with low coherence are not suitable for interferometric data processing. The coherence value is used as a parameter for adaptive phase noise suppression algorithms. It can also be used for surface classification tasks. The paper investigates the problem of the coherence estimate reducing under the influence of the topographic phase slope and considers ways to reduce the impact of the slope on the estimate value. The paper presents a comparative efficiency analysis of four methods for coherence maps calculation used for the phase noise suppression on the interferograms by a spectral adaptive filter in interferometric data processing for the Earth's remote sensing space radar ALOS PALSAR. © Published under licence by IOP Publishing Ltd

Излучение преобразователем волноводного типа в соосные с ним конусные полупространства

Introduction. The present stage of development of hydroacoustic equipment is characterized by a constant improvement of an element base and by an increase in computing power. However, in solving of applied problems one is increasingly faced with a restriction on the realized bandwidth of electroacoustic transducers and antennas. The most of well-known methods of bandwidth expansion do not provide a linear character of the phase-frequency characteristic (PFC) of radiation in the working frequency band, which is of primary importance for the effective formation of relatively short, frequency-tunable, and complex acoustic signals. From this position, the use of a transducer of waveguide type (TWT) is preferential. Its construction and electrical excitation method provides a close to linear phase response of radiation.Aim. The development of a generalized computational model. It has to include particular cases of TWT radiation into cylindrical waveguides coaxial with it and into half-spaces, and also to take into account the influence of waves reflected from the boundaries of the TWT on its field characteristics.Materials and methods. The TWT was presented by a coaxial set of identical water filled piezocylinders with amplitude-phase excitation, provided a mode of broadband radiation in the form of traveling waves. The usage of the method of partial regions allowed one to obtain a solution of the problem of TWT radiation through water filled apertures into the conical adjacent half-spaces, variable in angle.Results. Frequency characteristics of TWT sound pressure results calculated in accordance with the solution of the synthesis problem in the frontal and rear directions for different angles of cone opening were presented and analyzed. Using the proposed computational model of TWT, the possibility of obtaining a bandwidth of the order of 3 octaves was demonstrated. An influence of the thickness of the passive flanges, which are used to link the TWT in the antennas was estimated. The possibility of radiation in the working frequency band of TWT of ultrashort ultra-short single-period pulses for different angles of cone opening was considered. A comparative assessment of the result of calculation with other particular solutions (the radiation by TWT in coaxial water-filled waveguides and also – in half-spaces) was presentedConclusion. An expedient to use a generalized computational model for a more accurate description of the acoustic fields of real antenna models made up of TWT was concluded.Введение. Современный этап развития гидроакустической техники характеризуется постоянным улучшением элементной базы и ростом вычислительных мощностей. На этом этапе при решении прикладных задач все чаще сталкиваются с ограничением ширины полосы пропускания электроакустических преобразователей и антенн. Большинство известных способов расширения полосы пропускания не обеспечивают линейность фазочастотной характеристики (ФЧХ) излучения в рабочей полосе частот, которая имеет первоочередное значение для эффективного формирования сравнительно коротких, перестраиваемых по частоте и сложных по структуре акустических сигналов. В связи с этим преимущественным является использование преобразователя волноводного типа (ПВТ), способ построения и электрического возбуждения которого обеспечивает близкую к линейной ФЧХ излучения.Цель работы. Разработка обобщенной расчетной модели, которая включает в себя частные случаи излучения ПВТ в соосные с ним цилиндрические волноводы и в полупространства, а также учитывает влияние волн, отраженных от границ ПВТ, на его полевые характеристики.Материалы и методы. ПВТ представлен соосным набором идентичных водозаполненных пьезоцилиндров с амплитудно-фазовым возбуждением, обеспечивающим режим широкополосного излучения по типу бегущей волны. Использование метода частичных областей позволяет решить задачу об излучении ПВТ через водозаполненные апертуры в граничащие с ними конусные полупространства с изменяемым углом раскрыва.Результаты. Приведены и проанализированы результаты расчетов частотных характеристик звукового давления при излучении ПВТ, возбуждаемых в соответствии с решением задачи синтеза, во фронтальном и тыльном направлениях для разных углов раскрыва конусов. С использованием предложенной расчетной модели ПВТ показана возможность получения полосы пропускания порядка трех октав. Оценивается влияние толщины пассивных фланцев, которые используются для компоновки ПВТ в антеннах. Рассматривается возможность излучения в рабочей полосе частот ПВТ перестраиваемых по частоте ультракоротких однопериодных импульсов для разных углов раскрыва конусов. Дается сопоставительная оценка результатов расчета с другими частными решениями: излучение ПВТ в соосные водозаполненные волноводы, а также – в полупространства.Заключение. Сделан вывод о целесообразности использования обобщенной расчетной модели для более точного описания акустических полей реальных макетов антенн, составленных из ПВТ

From Interactive Open Learner Modelling to Intelligent Mentoring: STyLE-OLM and Beyond

STyLE-OLM (Dimitrova 2003 International Journal of Artificial Intelligence in Education, 13, 35–78) presented a framework for interactive open learner modelling which entails the development of the means by which learners can inspect, discuss and alter the learner model that has been jointly constructed by themselves and the system. This paper outlines the STyLE-OLM framework and reflects on the key challenges it addressed: (a) the design of an appropriate communication medium; this was addressed by proposing a structured language using diagrammatic presentations of conceptual graphs; (b) the management of the interaction with the learner; this was addressed by designing a framework for interactive open learner modelling dialogue utilising dialogue games; (c) the accommodation of different beliefs about the learner’s domain model; this was addressed with a mechanism for maintaining different views about the learner beliefs which adapted belief modal logic operators; and (d) the assessment of any resulting improvements in learner model accuracy and learner reflection; this was addressed in a user study with an instantiation of STyLE-OLM for diagnosing a learner’s knowledge of finance concept, as part of a larger project that developed an intelligent system to assist with learning domain terminology in a foreign language. Reviewing follow on work, we refer to projects by the authors’ students and colleagues leading to further extension and adoption of STyLE-OLM, as well as relevant approaches in open learner modelling which have cited the STyLE-OLM framework. The paper points at outstanding research challenges and outlines future a research direction to extend interactive open learner modelling towards mentor-like intelligent learning systems

Физико-географические закономерности формирования искусственных фирново-ледяных массивов

The paper presents results of analysis of diurnal and potentially possible efficiency of water freezing aimed at construction of artificial infiltration (firn-ice) masses on the Russia’s territory. A method of jet ice-formation (winter sprinkling) developed in Institute of Geography of the Russian Academy of Sciences is used for freezing of the artificial firn-ice masses. The method applies far-reaching (long-distance) sprinkler installations for spraying of water and formation of thick (more than 7 m for a day) masses of artificial firn. In winter the sprinkler allows freezing of both the monolithic ice and artificial firn. A practical implementation of this method is licensed and realized for construction of ice passages, bridges, and winter automobile roads. Testing of the method demonstrated that the artificial firn can be used for desalination and purification of polluted salt waters with high efficiency. That is stipulated by both, the high productivity of the method (about 1500 tons of artificial firn for a day at the air temperature of −20°С, and low mineralization of the firn relative to initial salt water. Winter sprinkling is carried out when mean daily air temperature drops below –5 ∞С. Estimating of productivity of the artificial firn and monolithic ice under present-day climatic conditions was made over the Russia’s territory. Analysis of the climate conditions for periods 2001–2010 and 1961–2000 have shown that reduction of the firn productivity changed from 5-10% in Siberia up to 20–40% in central and southern regions of the European Russia. At the present time, a potentially possible volume of the artificial firn freezing being produced in cold seasons changes from 500 thousand tons in northern areas of Yakutia down to 10 thousand in center of European Russia. Productivity of the monolithic ice freezing by a method of thin-layer water pouring is twice lower in central areas of Yakutia than on the Arctic seashores that is explained by differences in wind speeds. Potentially possible monolithic ice productivity made by means of thin-layer water pouring changes from 56 m of ice thickness in Northern Siberia down to 10 m in center of European Russia. The Northern Yakutia and the River Ob’ mouth are two areas of maximal productivity of this method.Построены карты суточной производительности намораживания искусственного фирна методом зимнего дождевания для каждого месяца с отрицательной температурой воздуха ниже −5 °С на территории России. Оценена потенциально возможная производительность намораживания ледяного материала методами зимнего дождевания и тонкослойным наливом в современных климатических условиях. Рассмотрена роль климатических изменений в снижении производительности намораживания в разных регионах России. Анализ климатических условий в 1961–2000 и 2001–2010 гг. показал, что на территории России производительность намораживания искусственного фирна снизилась с 5–10% в Сибири до 20–40% в центральных и южных районах Европейской территории России