bluuebunny/crossref_metadata_2025 huggingface dataset:
О криптографических свойствах алгоритмов, сопутствующих применению стандартов ГОСТ Р 34.11-2012 и ГОСТ Р 34.10-2012
Authors: Alekseev Evgeny Konstantinovich , Oshkin Igor' Borisovich , Popov Vladimir Olegovich , Smyshlyaev Stanislav Vitalevich
Published: February 2018

В ряде общепринятых моделей противника обосновываются криптографические свойства алгоритмов, сопутствующих применению стандартов ГОСТ Р 34.10-2012 и ГОСТ Р 34.11-2012: алгоритма выработки кода аутентификации сообщений, алгоритма генерации псевдослучайных последовательностей и алгоритма выработки ключа обмена. Выводы о стойкости этих алгоритмов базируются на свойствах алгоритма ГОСТ Р 34.11-2012 и классических теоретико-сложностных задач (распознавательной и вычислительной задач Диффи - Хеллмана).
Атаки на схемы электронной подписи, не учитываемые традиционными определениями стойкости, и меры противодействия им
Authors: Nikolaev Vasilii Dmitrievich
Published: February 2018

Изучается возможность проведения атак дублирования подписи на выбранном ключе на различные схемы электронной подписи. Рассматриваются меры противодействия таким атакам как на уровне протоколов, так и на уровне схем подписи.
Fault analysis of Kuznyechik
Authors: AlTawy R , Duman O , Youssef Amr M
Published: February 2018

Проводится анализ двух атак на шифр Кузнечик методом искажений. Показано, что если атакующий может искажать случайный байт в 7-м и 8-м раундах, то с помощью разностного метода он может найти ключ, используя в среднем 4 искажения. Другая атака относится к случаю, когда шифр имеет секретный S-бокс, и позволяет в модели искажений типа залипания байта на 0 восстанавливать как ключ, так и параметры секретного S-бокса. Это показывает необходимость защиты схемной и программной реализаций нового стандарта даже в случае применения секретного S-бокса.
Minimizing collisions for quantum hashing
Authors: Vasiliev Alexander Valeryevich , Ziiatdinov Mansur Tagirovich
Published: February 2018

Предлагаются явные алгоритмы вычисления параметров квантового хеширования, минимизирующих вероятность возникновения квантовых коллизий.
A graph of minimal distances between bent functions
Authors: Kolomeets Nikolai Aleksandrovich
Published: February 2018

Граф минимальных расстояний между булевыми функциями определяется как неориентированный граф $(V, E)$, где $V$ - множество всех бент-функций от $2k$ переменных и $(f, g) \in E$, если расстояние Хемминга между $f$ и $g$ равно $2^k$ (это минимально возможное расстояние между двумя бент-функциями). Показано, что его подграф, индуцированный всеми функциями, которые аффинно эквивалентны бент-функциям Майораны - МакФарланда, связен.
Some remarks on the elliptic curve discrete logarithm problem
Authors: Nesterenko Alexey Yur'evich
Published: February 2018

Предлагается алгоритм решения задачи дискретного логарифмирования на эллиптической кривой над конечным полем, использующий дополнительную информацию о мультипликативном порядке искомого решения и допускающий параллельную модификацию.
Рассеивающие свойства XSLP-шифров
Authors: Malyshev Fedor Mikhailovich , Trifonov Dmitrii Igorevich
Published: February 2018

Получена точная нижняя оценка числа локальных подстановок в XSLP-шифре с произвольным числом итераций, по сумме вероятностных линейных соотношений которых строится вероятностное линейное соотношение между знаками открытого и шифрованного текстов. В исследуемом шифре матрицы $L$ линейных преобразований являются блочно-диагональными с максимально рассеивающими блоками, а коммутации $P$ - равномерно рассеивающими.
Дискретные функции и разреженные системы дискретных уравнений
Authors: Smirnov Vladimir Georgievich
Published: February 2018

Даны определения классов дискретных функций и систем дискретных уравнений. Рассмотрены аналитические способы их задания. Предложен алгоритм определения совместности разреженной системы дискретных уравнений, использующий построение пути в графе решений системы по параметрическим решениям отдельных уравнений. Приведены примеры, иллюстрирующие работу алгоритма.
Исследование некоторых подклассов мультиаффинных, биюнктивных, слабо положительных и слабо отрицательных булевых функций
Authors: Gorshkov Sergei Pavlovich
Published: February 2018

Множества мультиаффинных (обозначается $A$), биюнктивных (или $2$-КНФ, $Bi$), слабо положительных (или антихорновских, $WP$) и слабо отрицательных (или хорновских, $WN$) булевых функций порождают классы полиномиально решаемых систем уравнений. Изучены классы функций $A\cap B$, $Bi\cap B$, где $B$ - множество бент-функций. Описаны множества возможных значений алгебраической степени нелинейности функций из классов $A$, $Bi$, $WP$, $WN$. Рассмотрены вопросы построения функций из классов $WP$, $WN$ на основе функций от меньшего числа переменных.
Многомерная теорема Пуассона для чисел решений случайных включений, близких к заданным векторам
Authors: Kopyttsev Viktor Alekseevich
Published: February 2018

Рассматривается число решений случайного включения над конечным полем, отличающихся от некоторого опорного вектора не более чем в заданном числе координат. Приводятся условия, при которых числа решений, связанные с несколькими опорными векторами, асимптотически независимы, а их распределения сходятся к пуассоновским распределениям, когда размерность векторов стремится к бесконечности.
Весовые дефициты инволюций и подстановок
Authors: Sachkov Vladimir Nikolaevich , Kruglov Igor Aleksandrovich
Published: February 2018

Пусть $E_{2^m}$ - упорядоченная аддитивная группа конечного поля из $2^m$ элементов. Для подстановки $S: E_{2^m}\to E_{2^m}$ вводится и изучается понятие индекса весового дефицита инволюции, соответствующей подстановке $S$. Этот индекс позволяет оценивать стойкость $S$-боксов относительно дифференциального метода криптоанализа. Описаны перечислительные алгоритмы для инволюций с заданными значениями весовых дефицитов.
Key agreement schemes based on linear groupoids
Authors: Baryshnikov Andrei Vladimirovich , Katyshev Sergey Yur'evich
Published: February 2018

Исследуется возможность использования одного класса неассоциативных группоидов (так называемых линейных группоидов) для реализации схемы выработки общего ключа, основанной на обобщении алгоритма Диффи-Хеллмана. Доказана необходимость использования коммутативности степеней и свойств эффективного вычисления степеней. Описан конкретный пример линейного группоида над группой точек эллиптической кривой.
Схема разделения секрета типа схемы Блэкли, основанная на пересечении подпространств
Authors: Kosolapov Yurii Vladimirovich
Published: February 2018

Рассматривается задача построения схемы разделения секрета, в которой возможна замена любого подмножества участников новыми участниками; при этом доли секрета вычисляются только для новых участников, а доли секрета у незамененных участников остаются прежними. С помощью теории помехоустойчивых кодов строятся протоколы разделения и восстановления секрета. Для исследования допустимых границ параметров построенной схемы распределения секрета вводится и исследуется новая характеристика линейного кода. В качестве примеров приводятся реализации предложенной схемы на основе некоторых кодов.
Сходимость матриц переходных вероятностей некоторых цепей Маркова на конечной абелевой группе к равномерной матрице
Authors: Kruglov Igor Aleksandrovich
Published: February 2018

Изучается класс конечных однородных цепей Маркова, связанных со схемой авторегрессии на конечных абелевых группах. В терминах параметров схемы авторегрессии найдены условия полной регулярности и точные формулы для среднеквадратического уклонения матриц переходных вероятностей за $N$ шагов от предельной равномерной матрицы.
Асимптотическое поведение мощности полного прообраза образа случайного множества при итерациях отображений конечного множества
Authors: Pil'shchikov D V
Published: February 2018

В связи с оценками сложности алгоритмов балансировки времени-памяти-данных возникают задачи оценки мощности полного прообраза образа случайного множества при многократных итерациях отображений. Предложена вероятностная модель, описывающая мощности исследуемых случайных множеств величинами, зависящими от числа частиц и суммарного числа частиц в процессе Гальтона-Ватсона. Найдены пределы математических ожиданий этих случайных величин
Bash-f: another LRX sponge function
Authors: Agievich Sergei Valer'evich , Marchuk V V , Maslov Aleksandr Sergeevich , Semenov Vladislav Igorevich
Published: February 2018

Предлагается семейство функций хэширования Bash, основанных на конструкции «губка». Основным элементом этого семейства является функция Bash-f, которая относится к LRX (Logical-Rotation-Xor) классу симметричных криптографических алгоритмов. Описаны компоненты Bash-f: нелинейное преобразование, линейные перемешивающие преобразования, перестановка векторов состояния функции. Для каждой компоненты критерии качества определяются таким образом, чтобы обеспечить возможность максимально объективного и прозрачного выбора компонент.
On the properties of the CTR encryption mode of Magma and Kuznyechik block ciphers with re-keying method based on CryptoPro Key Meshing
Authors: Akhmetzyanova L R , Alekseev Evgeny Konstantinovich , Oshkin Igor' Borisovich , Smyshlyaev Stanislav Vitalevich , Sonina L A
Published: February 2018

Для шифра Магма с преобразованием ключа методом CryptoPro Key Meshing ( CPKM ) получены оценки стойкости в рамках стандартной модели и модели с информацией из побочных каналов. Предложена модификация алгоритма преобразования ключа, улучшенная по сравнению с CPKM. Обсуждаются эксплуатационные характеристики шифра Кузнечик в режиме CTR для нескольких методов преобразования ключа.
Non-commutative Hamilton-Cayley theorem and roots of characteristic polynomials of skew maximal period linear recurrences over Galois rings
Authors: Goltvanitsa M A
Published: February 2018

Пусть $p$ - простое число, $q=p^r$, $R=\mathrm{GR}(q^d, p^d)$ - кольцо Галуа, $S = \mathrm{GR}(q^{nd}, p^d)$ - его расширение. Рассматриваются скрученные линейные рекуррентные последoвательности максимального периода (ЛРП МП) над $S$. В работе доказано некоммутативное обобщение хорошо известной теоремы Гамильтона-Кэли. С использованием этого результата устанавливается существование корней характеристических многочленов скрученных ЛРП МП в некотором расширении $\mathcal{K}$ кольца $\check{S}$. Изучается структура множества корней этих многочленов.
A new authenticated encryption mode for arbitrary block
cipher based on universal hash function
Authors: Nesterenko Alexey Yur'evich
Published: February 2018

В работе предлагается новый режим аутентифицированного шифрования, который является комбинацией хорошо известного режима XEX
(Xor-Encryption-Xor) и универсальной функции хэширования с заданными
свойствами из специального класса. Важной особенностью данного режима
является тот факт, что длина кода аутентификации в два раза превосходит длину входного блока используемого шифра. Другой важной особенностью является возможность распараллеливания. В работе приводятся описание режима,
обоснование его безопасности и рассматриваются вопросы практической реализации.
Параметрические модели случайных комбинаторных объектов экспоненциального типа и вопросы их вероятностно-статистического анализа
Authors: Ivchenko Grigorii Ivanovich , Medvedev Yurii Ivanovich
Published: February 2018

Работа посвящена исследованию некоторых проблем вероятностной комбинаторики, когда на множестве рассматриваемых комбинаторных
объектов задается некоторая параметрическая вероятностная мера. Проводится сравнительный анализ асимптотических свойств случайных $n$-подстановок и случайных разбиений $n$-множеств в однопараметрической модели.
Вероятностные линейные соотношения в двоичных рекуррентных последовательностях
Authors: Kozlitin Oleg Alekseevich
Published: February 2018

Рассматриваются алгебраические методы поиска вероятностных линейных соотношений, выполняющихся на отрезке двоичной линейной рекуррентной последовательности. Оценена трудоемкость предложенных алгоритмов.
Перестановочные решетки отношений эквивалентности на декартовых произведениях и согласованные с ними системы уравнений. II
Authors: Polin Sergei Vladimirovich
Published: February 2018

Описаны введенные автором ранее $GA$-решетки и соответствующие им просто решаемые системы уравнений.
Показатели рассеивания линейной среды AES-подобных алгоритмов шифрования
Authors: Fedchenko V A
Published: February 2018

В качестве модели для AES-подобных алгоритмов шифрования рассматриваются XSLP-шифры с условием, что все перестановки $P$ являются равномерно рассеивающими, а блоки матриц преобразований $L$ имеют фиксированный линейный (разностный) коэффициент рассеивания $\rho$. При всех допустимых $\rho$ получена точная нижняя оценка минимального количества локальных подстановок, участвующих в системах линейных (разностных) вероятностных соотношений для произвольного числа итераций XSLP-шифра.
Стабилизаторы некоторых семейств булевых функций от $n$ переменных, образующих Галуа-замкнутые подалгебры алгебры Шефера. II
Authors: Tarasov Alexey Vyacheslavovich
Published: February 2018

В статье завершено описание групп подстановок множества двоичных векторов длины $n$, стабилизирующих классы булевых функций от $n$ переменных из Галуа-замкнутых подалгебр алгебры Шефера.
Исследование сложности метода радужных таблиц с маркерами цепочек
Authors: Pil'shchikov D V
Published: February 2018

Вводится вероятностная модель оперативного этапа метода радужных таблиц с маркерaми цепочек и на ее основе рассчитывается средняя
временная сложность полной обработки одной таблицы. Выводятся двусторонние оценки этой величины и предлагается вычислительный подход к построению оптимального маркера. Использованная вероятностная модель в отличие от других моделей позволяет учитывать влияние дисперсии числа прообразов случайно и равновероятно выбранного элемента конечного множества
относительно однонаправленной функции.
Migración interna y mercado laboral en San Pedro Sula, Cortés, periodo 2006 y 2013
Authors: Fernández Henry Alberto
Published: February 2018

Al igual que en los demás países de Latinoamérica, en Honduras, la migración interna ha jugado un rol importante, tanto en el desarrollo económico, como en la distribución espacial de la población y la urbanización del país. No obstante, ha existido poco interés por estudiarla magnitud y direccionalidad de los flujos migratorios, en especial hacia San Pedro Sula. Es así, que el presente artículo, además de caracterizar la población migrante, la no migrante, incluye la tipología de migrantes (migrantes de toda la vida y migrantes recientes), estableciendo comparaciones entre estos grupos, en base a sus características sociodemográficas; para lo cual se utilizan datos de la Encuesta Permanente de Hogares de Propósitos Múltiples de mayo 2006 y 2013. La metodología utilizada consiste en el uso de la diferencia de medias para muestras independientes y la prueba de hipótesis, mediante la T de Student. Los resultados indican que las mujeres son más propensas a migrar y que los nativos cuentan en promedio con mayor nivel educativo que los migrantes. Además, perciben una media salarial ligeramente superior a la obtenida por la población migrante ocupada.
Bienestar subjetivo y su relación con el ingreso económico absoluto, el bienestar objetivo y la condición laboral, en habitantes del municipio de Tatumbla, Francisco Morazán, 2016.
Authors: Landa Blanco Miguel
Published: February 2018

La presente investigación tuvo como objetivo analizar el bienestar subjetivo, comprendido como satisfacción con la vida, en habitantes del casco urbano del municipio de Tatumbla, Francisco Morazán en Honduras. Temporalmente, el estudio se realizó en el primer semestre del año 2016. De manera particular, se estudió tal constructo en relación a variables tales como el ingreso económico, el bienestar objetivo y la condición laboral. Todo ello, por medio de un enfoque cuantitativo, con un diseño no experimental, de alcance relacional, en una temporalidad transversal. Para la recolección de información se elaboró una escala compuesta por tres dimensiones: egocéntrica, sociocéntrica y homeostática.Los resultados de la investigación indican que no existe relación estadística directa entre la variable bienestar subjetivo e ingreso económico absoluto. De igual manera, no existe relación significativa entre el bienestar objetivo y el subjetivo, salvo una correlación débil entre la tenencia de bienes materiales y los factores egocéntricos.Finalmente, se encontró que los individuos empleados reportan niveles más elevados de bienestar subjetivo, en comparación con los desempleados. Estos resultados se discuten desde los principios del desarrollo humano, valorando la utilidad metodológica del bienestar subjetivo para la detección de desigualdades e indicador de calidad de vida.
Adolescencia y aborto en Cuba. Percepciones de adolescentes y actores sociales
Authors: Álvarez Vázquez Luisa , Rodríguez Cabrera Aida , Avich Nelli Salomón , Domínguez Yuri Arnold
Published: February 2018

En la atención de salud reducir los casos de aborto es una prioridad en América Latina y el Caribe. Para disminuir esta práctica especialmente entre las adolescentes, se requiere emprender acciones conjuntas entre adolescentes y actores sociales. El objetivo de este artículo es identificar diferencias en las percepciones sobre el aborto en adolescentes y actores en el contexto geográfico de Cuba. Se analizó información cuantitativa disponible en las estadísticas continuas y resultados de las investigaciones realizadas, información de grupos focales (GF) y entrevistas en profundidad (EP), para valorar la forma de pensar de las adolescentes y otros actores sobre la decisión que conduce a abortar, así como losfactores relacionados. En Cuba en los años 80 el aborto entre mujeres de 12 a 49 años fue superior a 50 por mil y aunque ha disminuido, en el 2015 aún era de 30 por mil. Las adolescentes lo practican con frecuencia y poco se conoce cómo piensa la que aborta, su pareja, y la familia. Sobre la protección relacionada con el uso de métodos anticonceptivos, aunque existe el acceso que brindan los servicios de salud, los y las adolescentesreflejan disponer de información limitada. Mientras que los actores sociales indican que los y las adolescentes no atienden las orientaciones. No se observan los resultados positivos de las acciones realizadas en sector salud y educación para evitar y reducir esta práctica en adolescentes, por un lado los y las adolescentes se consideran no informados y por otro, los actores sociales perciben que los y las adolescentes no se dejan guiar.
Laser Doppler Flowmetry versatile acquisition system with low quantization error
Authors: Marrazzi Francesco , Truffer Frederic , Geiser Martial
Published: February 2018

The Laser Doppler Flowmetry (LDF) is a non-invasive technique used to evaluate blood perfusion of various human tissues like the skin or the fundus of the eye. It is based on the scattering of light on moving red blood cells in tissue. Frequency shifted scattered light is detected and provide an electrical signal. Physical models for LDF use the DC and AC components of this signal. If AC is small relative to the DC, digitalization becomes an issue, and if more than two LDF signal acquisitions and analysis have to be done simultaneously, the device becomes expensive and bulky. We propose here a versatile and inexpensive acquisition system, which overcomes quantization errors issue by first separating DC from AC, then amplifying AC and finally recombining both signals before digitalization. We designed an analog circuit combined with a 12 bit analog-to-digital converter, a microcontroller unit and a Raspberry Pi2 (Rpi2) for the signal processing. Results are accessed remotely from the Rpi2 through HTTP protocol. Multiple systems can easily be used simultaneously for multichannel acquisitions.
Research on Mission Pricing of Crowdsourcing APP
Authors: Jiang Shaoyan , Lin Songhao , Chen Yiquan , Zhang Yuanbiao
Published: February 2018

In order to have a better study of pricing of crowdsourcing APP tasks, mission data was collected about an already completed project, including the location, pricing and fulfillment of each mission. Get the law of the task pricing of the completed projects by analyzing the location distribution of the task points and the members, and then analyze the reason of the task failure. Besides, combine the information data of the members to improve the original pricing model based on the K-means clustering. Focus on the task package pricing, design a better task pricing model to improve the success rate of the task.
Determining Antecedent of Re-Purchase Intention: The Role of Perceived Value and Consumer’s Interest Factor
Authors: Can Yesim , Erdil Oya
Published: February 2018

With the widespread use of smartphones, strategic marketing of smartphones has become the focus of related brands. Although creating brand loyalty is an important factor of global strategic marketing and re-purchase intention, little research investigated the antecedent of smartphone's brand loyalty and repurchase intention. The purposes of this study are to investigate what are the antecedent brand loyalty and re-purchase intention in smartphone marketing. In the light of the literature and for this purpose; the effects of perceived value factor (perceived ease of use, perceived irreplaceability), utilitarian factor (system quality), hedonic factor (visual design), and consumer’s interest factor (technology consciousness) on brand loyalty and repurchase intention were investigated in an integrated model. The results of the analysis show that smartphone's re-purchase intention is largely determined by brand loyalty, perceived ease of use, perceived irreplaceability, system quality, visual design, and technology consciousness. Moreover, analysis results demonstrate that perceived irreplaceability, system quality, and visual design affect brand loyalty.
Creating Creative Thinking in Students: A Business Research Perspective
Authors: Wongpinunwatana Nitaya , Jantadej Kunlaya , Jantachoto Jamnong
Published: February 2018

The objective of this study is to investigate how to create creative thinking in students through encouraging students’ logical thinking, motivation, and collaborative learning. The study also attempts to find suitable teaching procedures for the research subject. This study is based on qualitative research. Participants were graduate students studying business research methods. The results indicate that logical thinking affects the analytical skill. This skill, in turn, affects students’ creative thinking. A model of creating creative thinking in students is proposed from the research findings. Instructors may consider using the modeling to boost creative thinking in students. In addition, the findings suggest that the main teaching processes should be as follows: Instructors should encourage students to use their logical reasoning during the conceptual framework development. Workshops on students’ research projects should be conducted so students can practice doing research. Students should make oral presentations of their projects and experts invited to comment on them. Collaborative technologies need to be introduced so that instructors and students can communicate with each other on assignments. Apart from collaborative tools, instructors can set up additional sessions after hours to allow students to discuss problems they are facing. Research classes should incorporate in the coursework three student presentations: problem statement, research proposal, and completed research report. Finally, instructors should form students into groups and establish roles for the members.
Regulation of Growth and Carbohydrate Metabolism in Rice (Oryza Sativa L.) seedlings by Selenium and Sulphate
Authors: Das Debarati , Das Prabal , Biswas Asok K
Published: February 2018

Selenium is an essential and also toxic trace element for organisms including plants. We studied the role of selenium (Na2SeO4) on growth and carbohydrate metabolism and its interaction with sulphate (Na2SO4) in rice (Oryza sativa L. cv. Satabdi) seedlings. Low concentration of selenium (2µM) showed stimulatory effect on growth as opposed to its higher concentration (50µM). Selenium was found to accumulate in a dose dependent linear pattern in the plant tissues. Exposure to selenate increased both reducing and non reducing sugar contents in the rice seedlings accompanied with an increase in the activities of sugar metabolizing enzymes like Sucrose Synthase (EC 2.4.1.13) and Sucrose Phosphate Synthase (EC 2.4.1.14). An increase in Starch Phosphorylase (EC 2.4.1.1) activity corresponded with the reduction in starch contents in the rice seedlings. Since Selenium is chemically analogous to sulphate, simultaneous application of sodium sulphate (10mM) and selenate (Na2SeO4) was found to ameliorate partially or totally all the tested parameters under selenate treatment alone resulting in alteration of growth and development of the test seedlings.
Natality and Disability
Authors: McCrary Lorraine Krall ,   Philosophy Documentation Center
Published: February 2018

Arendt’s “natality,” a promising foundation for humanness that might be expanded to include those with profound cognitive disabilities, emerges in part out of Arendt’s creative interpretation of Augustine. Returning to Augustine provides natality with resources to escape the weaknesses of Arendt’s thought when viewed from the perspective of disability theory: The traps of grounding human dignity in rationality, of downplaying expressions of creativity in non-political spheres, and of denigrating the role of the body.
Engineering Ethics in China
Authors: Zhang Hengli , Davis Michael ,   Philosophy Documentation Center
Published: February 2018

This article describes China’s century-long concern with the professional ethics of engineers, especially a succession of codes of engineering ethics going back at least to 1933. This description is the result both of our own archival research and of “philosophical history”, the application of concepts from the philosophy of professions to the facts historians (or we) have discovered. Engineers, historians, social scientists, and philosophers of technology, as well as students of professional ethics, should find this description interesting. It certainly provides a reason to wonder whether those who write about codes of professional ethics as if they were an Anglo-American export unlikely to put down roots elsewhere might have overlooked many early codes outside English-speaking countries. While code writers in China plainly learned from Western codes, the Chinese codes were not mere copies of their Western counterparts. Indeed, the Chinese codes sometimes differed inventively from Western codes in form (for example, being wholly positive) or content (for example, protecting local culture).
Learning design – pædagogiske og didaktiske modeller for undervisningsudvikling, kvalitetssikring og effektivisering på de videregående uddannelser
Authors: Buus Lillian , Godsk Mikkel , Hachmann Roland
Published: February 2018

Teknologi har for alvor vundet indpas på de videregående uddannelser i Danmark. Som et middel til at systematisere, kvalitetssikre og effektivisere brugen af teknologi i undervisningen og understøtte undervisningsudvikling, vinder “Learning Design” og andre lignende, modelbaserede tilgange i større og større grad frem ved såvel udenlandske som danske uddannelsesinstitutioner. Learning Design er bl.a. kendetegnet ved en systematisk tilgang til undervisningsudvikling baseret på pædagogisk teori samt værktøjer, metoder og modeller til at understøtte udviklingsprocessen (Conole, 2013). Endvidere har Learning Design vist sig nyttig til at kvalitetssikre anvendelsen af teknologi i undervisningen, at få konkretiseret pædagogisk teori til håndgribelige modeller og værktøjer for undervisningsudvikling målrettet underviserne samt muliggjort genbrug og deling af god praksis (Carvalho & Goodyear, 2014; Conole et. al., 2015; Hansen & Dohn, 2016; Laurillard, 2012; Mor et.al., 2014). Dermed rummer tilgangen også et forretningsmæssigt potentiale, da undervisningsudvikling kan systematiseres og således også være med til at realisere teknologiens potentialer for øget kvalitet i uddannelser og effektivisering.Dette nummer af LOM sætter særligt fokus på Learning Design og andre lignende, modelbaserede tilganges potentiale for at kvalitetssikre og effektivisere brugen af teknologi på de videregående uddannelser i Danmark gennem otte artikler, der på hver sin vis dokumenterer, hvordan Learning Design udmøntes i praksis.
Chaos, Bifurcations, and Their Control
Authors: Chen Guanrong
Published: February 2018

The article starts with a self‐contained brief overview of fundamental topics on nonlinear dynamics, chaos, and bifurcations, reaching out to the contemporary subjects of controlling chaos, controlling bifurcations, and anticontrolling chaos.

The section on nonlinear dynamics includes basic concepts of nonlinear dynamical systems, equilibria, limit sets, attractors, periodic orbit, limit cycles, Poincaré maps, homoclinic and heteroclinic orbits, Lyapunov stabilities, and the orbital stability of dynamical systems.

In the section on chaos theory, the concept of chaos and its dynamical features are first introduced, followed by some measures and testing methods of chaos. Fractals and chaos in control systems are briefly described. In parallel, the section on bifurcations introduces several typical types of bifurcations and the period‐doubling bifurcations route to chaos. Similarly, bifurcations in control systems are briefly discussed.

The above prepared the readers to step forward into the new realm of research on controlling chaos and controlling bifurcations, presented in the following two sections. Why chaos control and why bifurcation control are first motivated, by both theoretical challenges and real‐world examples. Then, some effective chaos control and bifurcation control methodologies are introduced, respectively, with distinctions from conventional control theory and techniques for nonchaotic especially linear systems.

The last section is novel and unique‐anticontrolling chaos in the sense of creating chaos or retaining chaos, by means of control, when chaos is beneficial. This topic has a great potential in nonconventional applications of control theory and practice, with a corpus of opportunities in future technology and engineering.
Neutral‐Point‐ClampedDC–ACPower Converters
Authors: Busquets‐Monge Sergio
Published: February 2018

This article reviews the fundamentals of multilevel multiphase neutral‐point‐clampedDC–ACpower converters. These converters are configured with one or more legs and a commonDC‐link. Each leg is functionally equivalent to a single‐pole multiple‐throw switch (n ≥ 3 positions) and it is implemented with a combination of only power semiconductor devices. The main leg topologies are initially presented, both active(transistor) clamped and passive(diode) clamped, for any number of levels. The leg switching states enabling all possible leg positions are subsequently discussed. Then, the set of all possible converter switching states and their standard representation in the converter space vector diagram is systematically derived, starting from the simplest converter (single‐phase single‐leg) up to the most complex converter with an arbitrary number of phases. The space vector diagram is illustrated for three‐, four‐, andn‐levels in the usual single‐phase and three‐phase cases. Once the converter states have been characterized, the most common converter control approaches are introduced on the basis of the space vector diagram, including space vector control, space vector modulation, programmed pulse width modulation, hysteresis control, and predictive control. These control strategies are illustrated in simple and conventionalDC–ACconverter configurations. Finally, the article discusses theDC‐link capacitor voltage balance problem, which is inherent to these topologies whenever theDC‐link is configured with a capacitive voltage divider. The basics of the different solutions to guarantee the balancing are presented, both through the inclusion of additional hardware and through the application of a suitable converter control strategy.
Three‐Dimensional Failure Patterns Around an Inflating Magmatic Chamber
Authors: Gerbault Muriel , Hassani Riad , Novoa Lizama Camila , Souche Alban
Published: February 2018

Bedrock failure around an inflating magma chamber is an important factor that controls the occurrence of volcanic eruptions. Here, we employ 3‐D numerical models of elasto‐plastic shear failure around an inflating crustal reservoir, to study how the induced failure patterns depend on the geometry of the chamber, on the host rock strength and on the gravitational field. Our simulations show that either localized or diffuse plastic failure domains develop in 3 stages. Failure initiates (stage 1) after a critical overpressure is reached, the value of which depends on effective host rock strength. Next, and with increasing applied overpressure, either distributed (for zero friction angle) or localized plastic failure zones (for 30
friction angle) form (stage 2), until they finally connect to the surface (stage 3). Cylindrical chambers develop prismatic shear zones that merge from the surface and chamber walls. For spherical and prolate chambers, diffuse conical zones of failure develop from the chamber's crest, whereas for oblate symmetrical chambers, shear bands initiate at the horizontal tips but bend back above the center of the chamber to reach the surface. In contrast for asymmetrical oblate chambers, shear bands initiate in their cylindrical section and vanish along the elongated direction. Here, magmatic fluids may migrate both through diffuse elastic dilation zones at the tips, and through localized shear zones from the crest. Our results thus suggest how natural observations may be used to constrain the mode of failure occurring underneath a volcano. We discuss several natural examples in this context.
Stratiform and Convective Precipitation Properties of Tropical Cyclones in the Northwest Pacific
Authors: Yang Zhaohong , Yuan Tie , Jiang Haiyan , Zhang Lei , Zhang Chen
Published: February 2018

The properties of stratiform and the convective precipitation of tropical cyclones (TCs) over the northwest Pacific are examined using the Tropical Rainfall Measuring Mission data for 1998–2013. TCs are classified into inner core (IC), inner rainband (IB), and outer rainband (OB) regions, and the results show that TCs are dominated by stratiform precipitation, which accounts for more than 78% of the total raining area. The highest fraction of the stratiform raining area exists in the IB region and increases as the TC intensity increases (from 80% to 93%). Strong convective signatures generally occur in the IC region, less often in the IB region, and least often in the OB region. Stratiform precipitation in the IC region generally has comparable or even stronger ice scattering signatures and higher 20 dBZ radar echo heights than the convective precipitation in the IB and OB regions. Weak convection decreases significantly as the TC intensity increases, which leads to increased convective intensity. Stratiform (convective) precipitation accounts for 61% (39%) of the total TC volumetric rain and 25% (75%) of the total TC lightning flash, respectively. Moreover, stratiform precipitation's contribution to the total TC volumetric rain and lightning flash increases as the TC intensity increases, which indicates that stronger TCs are favorable for maintaining more stratiform precipitation. The stratiform and convective precipitation properties in different TC regions and intensities cooperatively change with the enhanced ascending branch in the IC region and the radial outflow at the upper levels of the secondary circulation.
Direct Growth of Edge‐Rich Graphene with Tunable Dielectric Properties in Porous Si3N4 Ceramic for Broadband High‐Performance Microwave Absorption
Authors: Ye Fang , Song Qiang , Zhang Zhenchuang , Li Wei , Zhang Shouyang , Yin Xiaowei , Zhou Yuzhao , Tao Huiwen , Liu Yongsheng , Cheng Laifei , Zhang Litong , Li Hejun
Published: February 2018

High‐performance graphene microwave absorption materials are highly desirable in daily life and some extreme situations. A simple technique for the direct growth of graphene as absorption fillers in wave‐transmitting matrices is of paramount importance to bring it to real‐world application. Herein, a simple chemical vapor deposition (CVD) route for the direct growth of edge‐rich graphene (ERG) with tailored structures and tunable dielectric properties in porous Si3N4 ceramics using only methyl alcohol (CH3OH) as precursor is reported. The large O/C atomic ratio of CH3OH helps to build a mild oxidizing atmosphere and leads to a unique structure featuring open graphite nanosteps and freestanding nanoplanes, endowing the ERG/Si3N4 hybrid with an appropriate balance between good impedance matching and strong loss capacity. Accordingly, the prepared materials exhibit superior electromagnetic wave absorption, far surpassing that of traditional CVD graphene and reduced graphene oxide‐based materials, achieving an effective absorption bandwidth of 4.2 GHz covering the entire X band, with a thickness of 3.75 mm and a negligibly low loading content of absorbents. The results provide new insights for developing novel microwave absorption materials with strong reflection loss and wide absorption frequency range.
Quantum Emitters in Hexagonal Boron Nitride Have Spectrally Tunable Quantum Efficiency
Authors: Schell Andreas W. , Svedendahl Mikael , Quidant Romain
Published: February 2018

Understanding the properties of novel solid‐state quantum emitters is pivotal for a variety of applications in research fields ranging from quantum optics to biology. Recently discovered defects in hexagonal boron nitride are especially interesting, as they offer much desired characteristics such as narrow emission lines and photostability. Here, the dependence of the emission on the excitation wavelength is studied. It is found that, in order to achieve bright single‐photon emission with high quantum efficiency, the excitation wavelength has to be matched to the emitter. This is a strong indication that the emitters possess a complex level scheme and cannot be described by a simple two or three‐level system. Using this excitation dependence of the emission, further insight to the internal level scheme is gained and it is demonstrated how to distinguish different emitters both spatially as well as in terms of their photon correlations.
Engineering Extracellular Vesicles with the Tools of Enzyme Prodrug Therapy
Authors: Fuhrmann Gregor , Chandrawati Rona , Parmar Paresh A. , Keane Timothy J. , Maynard Stephanie A. , Bertazzo Sergio , Stevens Molly M.
Published: February 2018

Extracellular vesicles (EVs) have recently gained significant attention as important mediators of intercellular communication, potential drug carriers, and disease biomarkers. These natural cell‐derived nanoparticles are postulated to be biocompatible, stable under physiological conditions, and to show reduced immunogenicity as compared to other synthetic nanoparticles. Although initial clinical trials are ongoing, the use of EVs for therapeutic applications may be limited due to undesired off‐target activity and potential “dilution effects” upon systemic administration which may affect their ability to reach their target tissues. To fully exploit their therapeutic potential, EVs are embedded into implantable biomaterials designed to achieve local delivery of therapeutics taking advantage of enzyme prodrug therapy (EPT). In this first application of EVs for an EPT approach, EVs are used as smart carriers for stabilizing enzymes in a hydrogel for local controlled conversion of benign prodrugs to active antiinflammatory compounds. It is shown that the natural EVs' antiinflammatory potential is comparable or superior to synthetic carriers, in particular upon repeated long‐term incubations and in different macrophage models of inflammation. Moreover, density‐dependent color scanning electron microscopy imaging of EVs in a hydrogel is presented herein, an impactful tool for further understanding EVs in biological settings.
The long‐tail of online grocery shopping
Authors: Richards Timothy J. , Rabinovich Elliot
Published: February 2018

The “retail long tail” effect implies that both the level and concentration of sales moves to slower selling products in online environments, and total sales rise. We analyze the effect of assortment variation on store sales using data from an online food seller in the Eastern United States. We find that the long‐tail effect is more important in niche categories, deeper assortments are associated with a flatter distribution of sales, and total sales rise with variety. Our findings support the existence of a long tail in online food retailing. [EconLit citations: L16, L81, M31]
Velocity variation effect in fixed bed columns: A case study of CO2 capture using porous solid adsorbents
Authors: Al‐Janabi Nadeen , Vakili Reza , Kalumpasut Patthadon , Gorgojo Patricia , Siperstein Flor R. , Fan Xiaolei , McCloskey Paschal
Published: February 2018

This study shows that for a reliable evaluation of porous adsorbents for carbon capture based on the fixed bed adsorption analysis, one must consider the effect of velocity variation due to adsorption to make a fair judgment on predicting the performance of materials under flow conditions. A combined experimental and numerical study of CO2/N2 adsorption in fixed beds using three forms of adsorbents of amorphous powder (bulk activated carbon, AC), crystalline powder (bulk CuBTC metal‐organic framework, MOF) and crystalline pellets (pelleted CuBTC) was carried out to show the effect of velocity variation on CO2 breakthrough curves. Significant deviations are observed in the estimated amount adsorbed calculated from fixed bed experiments when models used for interpretation the measured data consider constant gas velocity because the stoichiometric time is underestimated. We show that the difference in breakthrough times estimated in models that consider constant and variable gas velocity grows exponentially with the feed gas concentration. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2189–2197, 2018
The role of wettability of nonideal nozzle plate: From drop‐on‐demand droplet jetting to impact on solid substrate
Authors: Zhang Lei , Ku Tao , Jia Jingsong , Cheng Xiaoding
Published: February 2018

The dynamics of drop‐on‐demand (DoD) droplet formation and subsequently impact on the solid substrate are investigated using a three‐dimensional (3‐D) multirelaxation‐time (MRT) pseudopotential lattice Boltzmann (LB) model. The wettability of nonideal nozzle plate and solid substrate is modeled by a geometric scheme within the LB framework. The dynamics of droplet formation are explored in a range of the inverse of Ohnesorge number
,
, and
, and the Reynolds number
,
, and
. For
, no satellite droplet is observed and the wettability of nozzle plate greatly influences the velocity and length of jetting fluids. For
, the filament breakup and recombination are observed. The moment of filament breakup is delayed with advancing contact angle
increasing. For
with
, the primary and satellite droplets could not be recombined with
and
which agree with the literature. Whereas with
, the recombination occurs. The dynamics of subsequent oscillating droplet impact on the substrate are similar to that of equilibrium droplet which could obtain high‐resolution printed features. Consequently, considering
with large
and
numbers, the printable range could be extended which could help increase the printing frequency and boost the production outputs of inkjet printing. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2837–2850, 2018
Modeling of hydrogen separation through porous YSZ hollow fiber‐supported graphene oxide membrane
Authors: Jin Yun , Meng Xiuxia , Yang Naitao , Meng Bo , Sunarso Jaka , Liu Shaomin
Published: February 2018

In this work, hydrogen (H2) permeation fluxes through 230 nm‐thick graphene oxide (GO) membrane deposited on porous YSZ hollow fiber were measured and correlated to an explicit H2 permeation model. H2 fluxes through such GO‐YSZ hollow fiber membrane increased from 4.83 × 10−8 mol cm−2 s−1 to 2.11 × 10−7 mol cm−2 s−1 with temperature rise from 20 to 100 °C. The activation energy of H2 permeation was determined by the linear regression of the experimental data and was applied in the theoretical calculations. The model predictions fit well the temperature dependent and the argon sweep gas flow rate dependent H2 fluxes data. Using the derived permeation model, the effects of vacuum pressure at lumen side and H2 partial pressure at shell side, membrane area, and GO membrane film thickness on the membrane performance were simulated and discussed to provide insights for practical applications. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2711–2720, 2018
Design, Synthesis, and Application of Chiral C2‐Symmetric Spiroketal‐Containing Ligands in Transition‐Metal Catalysis
Authors: Argüelles Alonso J. , Sun Siyuan , Budaitis Brenna G. , Nagorny Pavel
Published: February 2018

We present an expedient and economical route to a new spiroketal‐based C2‐symmetric chiral scaffold, termed SPIROL. Based on this spirocyclic scaffold, several chiral ligands were generated. These ligands were successfully employed in an array of stereoselective transformations, including in iridium‐catalyzed hydroarylations (up to 95 % ee), palladium‐catalyzed allylic alkylations (up to 97 % ee), intermolecular palladium‐catalyzed Heck couplings (up to 94 % ee), and rhodium‐catalyzed dehydroalanine hydrogenation (up to 93 % ee).
Spectroscopic and Computational Characterization of Diethylenetriaminepentaacetic Acid/Transplutonium Chelates: Evidencing Heterogeneity in the Heavy Actinide(III) Series
Authors: Deblonde Gauthier J.‐P. , Kelley Morgan P. , Su Jing , Batista Enrique R. , Yang Ping , Booth Corwin H. , Abergel Rebecca J.
Published: February 2018

The chemistry of trivalent transplutonium ions (Am3+, Cm3+, Bk3+, Cf3+, Es3+…) is usually perceived as monotonic and paralleling that of the trivalent lanthanide series. Herein, we present the first extended X‐ray absorption fine structure (EXAFS) study performed on a series of aqueous heavy actinide chelates, extending past Cm. The results obtained on diethylenetriaminepentaacetic acid (DTPA) complexes of trivalent Am, Cm, Bk, and Cf show a break to much shorter metal–oxygen nearest‐neighbor bond lengths in the case of Cf3+. Corroborating those results, density functional theory calculations, extended to Es3+, suggest that the shorter Cf−O and Es−O bonds could arise from the departure of the coordinated water molecule and contraction of the ligand around the metal relative to the other [MIIIDTPA(H2O)]2− (M=Am, Cm, Bk) complexes. Taken together, these experimental and theoretical results demonstrate inhomogeneity within the trivalent transplutonium series that has been insinuated and debated in recent years, and that may also be leveraged for future nuclear waste reprocessing technologies.
Dual C(sp3)−H Bond Functionalization of N‐Heterocycles through Sequential Visible‐Light Photocatalyzed Dehydrogenation/[2+2] Cycloaddition Reactions
Authors: Xu Guo‐Qiang , Xu Ji‐Tao , Feng Zhi‐Tao , Liang Hui , Wang Zhu‐Yin , Qin Yong , Xu Peng‐Fei
Published: February 2018

Herein we describe a mild method for the dual C(sp3)−H bond functionalization of saturated nitrogen‐containing heterocycles through a sequential visible‐light photocatalyzed dehydrogenation/[2+2] cycloaddition procedure. As a complementary approach to the well‐established use of iminium ion and α‐amino radical intermediates, the elusive cyclic enamine intermediates were effectively generated by photoredox catalysis under mild conditions and efficiently captured by acetylene esters to form a wide array of bicyclic amino acid derivatives, thus enabling the simultaneous functionalization of two vicinal C(sp3)−H bonds.