Ontology rules application for efficient career choice

[EN] The aim of this work is to help university applicants in their transition phase from high-school to tertiary education starting with their first life-long decision concerning their choice of the field of study. The construction of the decision support system has evolved into an ontology-based model. The model, as well as the decision making rules, have been formulated based on the research study of the cohort of 69000 students of the University of Alicante between 2010 and 2018. The educational and psychological processes have been studied in order to identify the pivot moments and the factors that may lead to an adequate decision making or to an objectively wrong decision which eventually ends up in a drop-out of studies. Analysing the existing methods of occupational and educational choice assistance, the method of John L. Holland on “A Psychological Classification of Occupations” has been selected as the most viable and convenient for this purpose. The Holland Codes have been adopted as a lingua franca of this ontology-based model. As a result, the ontology-based decision support system provides assistance in decision making using the Holland Code terminology and practically unlimited complexity of the object and data properties of and ontological presentation of knowledge.This work made use of the methods and models developed under the RFBR Grant 18-00-00238 "Methods and models of the intellectual decision support in innovative project management on the basis of knowledge of engineering".Startseva, E.; Grimaylo, A.; Chernyahovskaya, L.; Llopis Pascual, F. (2019). Ontology rules application for efficient career choice. En HEAD'19. 5th International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 1179-1186. https://doi.org/10.4995/HEAD19.2019.9251OCS1179118

Ingeniería de conocimiento para la mejora de la orientación académica (2015-2020)

Elegir el grado universitario que van a cursar es una decisión muy importante para muchos jóvenes que carecen de experiencias previas en este sentido. El objetivo principal de este trabajo es construir el sistema de apoyo a la toma de decisión sobre una base de conocimiento modular. En este caso, los módulos que definen las directrices de capacitación se forman conjuntamente con los expertos y se fundan en el método de Holland. Permitirá al usuario, en primer lugar, definir una modalidad académica elegida en la escuela secundaria y solo después ser definido con una carrera universitaria, dentro de la rama de conocimiento establecida. Se ha desarrollado BPMN-modelo del proceso a la toma de decisiones para elegir la mejor carrera universitaria. Se han identificado los factores significativos con método de análisis jerárquico, el efecto de los cuales se correlaciona directamente con los resultados de elección de la carrera universitaria y, además, afectan al rendimiento de los estudiantes. Se ha desarrollado la ontología con las interrelaciones entre los factores clave. Se ha formado del principio modular un base de conocimiento. Se han elaborado satisfactoriamente las reglas de entrada a la universidad, las reglas de elección de la rama de los estudios universitarios, y las reglas para mejorar el rendimiento académico con la finalización satisfactoria de los estudios universitarios. Con los resultados obtenidos y que se presenten en el trabajo, podemos concluir que se pueda lograr el objetivo principal del estudio para optimizar tiempo dedicado a los estudios y mejorar la calidad de vida y el rendimiento académico de los estudiantes de una carrera universitaria. Además, permite poder anticipar los itinerarios a elegir durante la etapa de educación secundaria para así incrementar su preparación

Investigation of wave processes of transformer windings as a distributed electric circuit

Relevance of the work is caused by the need of localize the defects of the transformer windings at diagnosis. It is possible to determine the spatial location of the defects along the transformer winding only if the transformer is considered as a system with distributed parameters. The main aim of the study is to present the transformer winding in the form of distributed electric circuit and to study the transients of such a circuit in two cases, at grounded winding end and at open winding end; to determine primary and steady voltage distribution along the transformer windings at the grounded winding end and open winding end; to search for possible ways to overcome the overvoltage arising along the transformer winding. The aim of the work is to obtain as well the transitional function caused by a unit action, in order to use subsequently the Duhamel integral which allows obtaining the transients in the transformer winding at an arbitrary external action. The methods used in the study are based on equations solution in partial derivatives using Laplace transform and transfer functions. It uses the initial conditions along the transformer winding and the boundary conditions at the ends of the windings. The final solution of partial differential equations is represented as a series, that is in the form of wave superposition with different frequencies. The results. The obtained transfer function of the voltage distribution along transformer windings allows determining: primary and steady stress distribution; over-voltage transient conditions; optimal values of distributed capacitance, and minimizing overvoltage along the winding

Investigation of wave processes of transformer windings as a distributed electric circuit

Relevance of the work is caused by the need of localize the defects of the transformer windings at diagnosis. It is possible to determine the spatial location of the defects along the transformer winding only if the transformer is considered as a system with distributed parameters. The main aim of the study is to present the transformer winding in the form of distributed electric circuit and to study the transients of such a circuit in two cases, at grounded winding end and at open winding end; to determine primary and steady voltage distribution along the transformer windings at the grounded winding end and open winding end; to search for possible ways to overcome the overvoltage arising along the transformer winding. The aim of the work is to obtain as well the transitional function caused by a unit action, in order to use subsequently the Duhamel integral which allows obtaining the transients in the transformer winding at an arbitrary external action. The methods used in the study are based on equations solution in partial derivatives using Laplace transform and transfer functions. It uses the initial conditions along the transformer winding and the boundary conditions at the ends of the windings. The final solution of partial differential equations is represented as a series, that is in the form of wave superposition with different frequencies. The results. The obtained transfer function of the voltage distribution along transformer windings allows determining: primary and steady stress distribution; over-voltage transient conditions; optimal values of distributed capacitance, and minimizing overvoltage along the winding

Calculation of equivalent distributed circuit parameters of transformer winding under the influence of skin effect

The relevance of the work. When producing, transporting and processing geo assets it is necessary to use various electrical equipment, the transformers are the main electricity distributors in this case. In some cases it is necessary to route the local electric network to recharge electric power devices for processing geo assets, the transformers are the main units of network as well. The efficiency of electric networks depends on the state of distribution devices - transformers, especially on the condition of the transformer windings. Therefore, the investigation and modeling of the transformer windings are the important tasks. When presenting the transformer windings as a distributed system we need to know the values of the equivalent circuit elements. In the presence of high-frequency currents in the circuit, the skin effect - the dependence of current on frequency - influences the value of equivalent circuit elements. The relevance of the research is caused by the fact that the pulse of nanosecond duration, which spectrum is filled with high frequencies, is used as the probe pulse for the transformer. The high frequency of the probe pulse provokes the skin effect, which, in its turn, contributes the frequency dependence to the value of the equivalent circuit parameters. The aim of the research is to introduce the probe nanosecond pulse as a superposition of harmonics with different frequencies; to calculate inductance and resistance for the transformer equivalent circuit for each harmonic with fixed frequency, which forms the pulse; to determine the values of inductance and capacitance using the calculation of electromagnet field and taking into account the skin effect as well. The energy of the calculated electromagnetic field allows retrieving the inductance and resistance values of the investigated system at the fixed frequency. To get the resulting equivalent circuit, which consists of combined circuits obtained for each frequency separately, using superposition principle; to obtain voltage and currents of equivalent circuit of transformer windings and compare them with the experimental data. Methods of investigation. The method of investigation is based on superposition principle, which means the expansion of arbitrary functions to the Fourier series. The authors use as well the numerical solution of partial differential equations - Helmholtz equation using the finite element method. To implement the method of finite elements the mathematical package COMSOL Multyhpisics was used. Results: The authors carried out frequency decomposition of nanosecond pulse and use it as a probe signal for transformer diagnosis. Based on the solution of Maxwell's equations the spatial distribution pattern of the magnetic vector potential was obtained. To extract the information on the inductance and resistance of the equivalent circuit of transformer winding the vector magnetic potential was used. The authors obtained the graphs of inductance and resistance of equivalent circuit for the transformer winding as a function of frequency. Graphical dependences are given for a variety of cross-sections of the transformer windings: round and rectangular shapes. Based on the obtained graphical dependencies the equivalent circuits of the transformer windings with the possible influence of the skin effect were built. The paper introduces the calculations of voltage and current of transformer windings using the equivalent circuit, as well as the results of comparison of theoretical calculations with the experimental ones

Las ciencias en la enseñanza secundaria como factor fundamental para el éxito universitario

Elegir el grado universitario que van a cursar es una decisión muy importante para muchos jóvenes que carecen de experiencias previas en este sentido. El objetivo principal de este trabajo es identificar los factores significativos que afectan al rendimiento de los estudiantes en la universidad y recomendar algunas normas que permitan orientar en la toma de decisiones a los estudiantes que van a ingresar en la universidad. Además, el estudio realizado puede ayudar a la selección de itinerarios o asignaturas que los estudiantes deberían elegir en su etapa de educación secundaria para abordar con mayores probabilidades de éxito la finalización de un grado universitario en concreto. Este estudio se basó en información estadística de casi 62.000 estudiantes (40% de hombres y 60% de mujeres) que ingresaron en la Universidad de Alicante en los últimos cursos. La información que se ha procesado incluía notas de admisión (puntuaciones de entrada de los exámenes realizados en las pruebas de acceso), rendimiento en el primer año (tasa de aprobados), edad, sexo, áreas de estudio universitario, cursos de carrera de pregrado y programas de estudio de secundaria. El objetivo ha sido el de identificar las interrelaciones entre los indicadores clave. Con los resultados obtenidos y que se presentan en este trabajo, podemos concluir que sí se puede obtener información relevante que ayude al futuro estudiante universitario a elegir adecuadamente el grado a cursar. Además, permite poder anticipar los itinerarios a elegir durante la etapa de educación secundaria para así incrementar su preparación

Calculation of equivalent distributed circuit parameters of transformer winding under the influence of skin effect

The relevance of the work. When producing, transporting and processing geo assets it is necessary to use various electrical equipment, the transformers are the main electricity distributors in this case. In some cases it is necessary to route the local electric network to recharge electric power devices for processing geo assets, the transformers are the main units of network as well. The efficiency of electric networks depends on the state of distribution devices - transformers, especially on the condition of the transformer windings. Therefore, the investigation and modeling of the transformer windings are the important tasks. When presenting the transformer windings as a distributed system we need to know the values of the equivalent circuit elements. In the presence of high-frequency currents in the circuit, the skin effect - the dependence of current on frequency - influences the value of equivalent circuit elements. The relevance of the research is caused by the fact that the pulse of nanosecond duration, which spectrum is filled with high frequencies, is used as the probe pulse for the transformer. The high frequency of the probe pulse provokes the skin effect, which, in its turn, contributes the frequency dependence to the value of the equivalent circuit parameters. The aim of the research is to introduce the probe nanosecond pulse as a superposition of harmonics with different frequencies; to calculate inductance and resistance for the transformer equivalent circuit for each harmonic with fixed frequency, which forms the pulse; to determine the values of inductance and capacitance using the calculation of electromagnet field and taking into account the skin effect as well. The energy of the calculated electromagnetic field allows retrieving the inductance and resistance values of the investigated system at the fixed frequency. To get the resulting equivalent circuit, which consists of combined circuits obtained for each frequency separately, using superposition principle; to obtain voltage and currents of equivalent circuit of transformer windings and compare them with the experimental data. Methods of investigation. The method of investigation is based on superposition principle, which means the expansion of arbitrary functions to the Fourier series. The authors use as well the numerical solution of partial differential equations - Helmholtz equation using the finite element method. To implement the method of finite elements the mathematical package COMSOL Multyhpisics was used. Results: The authors carried out frequency decomposition of nanosecond pulse and use it as a probe signal for transformer diagnosis. Based on the solution of Maxwell's equations the spatial distribution pattern of the magnetic vector potential was obtained. To extract the information on the inductance and resistance of the equivalent circuit of transformer winding the vector magnetic potential was used. The authors obtained the graphs of inductance and resistance of equivalent circuit for the transformer winding as a function of frequency. Graphical dependences are given for a variety of cross-sections of the transformer windings: round and rectangular shapes. Based on the obtained graphical dependencies the equivalent circuits of the transformer windings with the possible influence of the skin effect were built. The paper introduces the calculations of voltage and current of transformer windings using the equivalent circuit, as well as the results of comparison of theoretical calculations with the experimental ones

Las ciencias en la enseñanza secundaria como factor fundamental para el éxito universitario

Elegir el grado universitario que van a cursar es una decisión muy importante para muchos jóvenes que carecen de experiencias previas en este sentido. El objetivo principal de este trabajo es identificar los factores significativos que afectan al rendimiento de los estudiantes en la universidad y recomendar algunas normas que permitan orientar en la toma de decisiones a los estudiantes que van a ingresar en la universidad. Además, el estudio realizado puede ayudar a la selección de itinerarios o asignaturas que los estudiantes deberían elegir en su etapa de educación secundaria para abordar con mayores probabilidades de éxito la finalización de un grado universitario en concreto. Este estudio se basó en información estadística de casi 62.000 estudiantes (40% de hombres y 60% de mujeres) que ingresaron en la Universidad de Alicante en los últimos cursos. La información que se ha procesado incluía notas de admisión (puntuaciones de entrada de los exámenes realizados en las pruebas de acceso), rendimiento en el primer año (tasa de aprobados), edad, sexo, áreas de estudio universitario, cursos de carrera de pregrado y programas de estudio de secundaria. El objetivo ha sido el de identificar las interrelaciones entre los indicadores clave. Con los resultados obtenidos y que se presentan en este trabajo, podemos concluir que sí se puede obtener información relevante que ayude al futuro estudiante universitario a elegir adecuadamente el grado a cursar. Además, permite poder anticipar los itinerarios a elegir durante la etapa de educación secundaria para así incrementar su preparación

Laboratory evaluation of the hormonal agents effects on the plasma hemostasis system in women of reproductive age

Background: With the evolution of hormonal contraception, such as implementation of low dose agents, new regiments and administration routes of contraceptives, the risk of thrombotic complications persists, although is decreasing. The search for an available test for hemostasis assessment, which would allow for the prediction of thrombotic complications in high risk patients, remains relevant. Global tests for hemostasis assessment, such as thrombin generation test and thrombodynamics test, are attracting the specialists' attention due to the possibility of a quick integrative assessment of plasma hemostasis, especially during choice and tailoring of an optimal version of hormonal therapy. Aim: To assess the value of the integral thrombodynamics test in the multifactorial assessment of hemostasis system in women of reproductive age using hormonal contraceptives. Materials and methods: This observational prospective comparative study included 408 women aged 18 to 49 years followed from 2018 to 2022 in The Nikiforov Russian Center of Emergency and Radiation Medicine and Centre of Miscarriage Prevention and Treatment of the Maternity Hospital No. 1, St. Petersburg. From these, 208 women (mean age, 38.0 ± 7.0 years) were taking hormonal contraceptives (HC+ group), and 200 women (mean age, 37.5 ± 9.2 years) were in the control group (HC-). In the HC+ group, 163 women were taking combination oral contraceptives, 24 had an intrauterine levonorgestrel-releasing system, 8 used vaginal rings, and 13 were using progestin only oral contraceptives. Multifactorial clinical and laboratory assessment included taking past history, measurement of pro- and anticoagulation blood parameters, fibrinolysis, and endothelial function parameters (automatic coagulometer ACL TOP 500, Instrumentation Laboratory, USA). The integral assessment of the hemostasis system was performed with Thrombodynamics Registrator T-2 (Hemacor, Russia). Results: The groups were similar as per their age, chronic venous insufficiency and smoking. The HC+ group had significantly higher proportion of women with cardiovascular disorders (p = 0.0037), obesity (p = 0.0004), and headache (p 0.0001), compared to the HC- group. The thrombodynamics test showed a significantly higher rate of clot formation in the women taking hormonal contraception, compared to that in the HC- group (36.2 [30.1; 43.6] and 30.3 [28.0; 33.6] mcm/min, respectively, p 0.001). Hypercoagulation identified by the thrombodynamics test was associated with slowing down of XIIa-dependent fibrinolysis (6 [5; 8] min in the HC- and 12.8 [8; 16] min in the HC+ group, p 0,001) and higher levels of endothelial dysfunction markers (FVIII, 113 [85; 156] and 150 [107; 180]%, p = 0.015; vFW, 98 [85; 133] and 146 [95; 168]%, respectively, p = 0.003). The analysis of plasma hemostasis parameters depending on the presence of thromboembolic risk factors has shown that higher number of the risk factors is associated with higher velocity parameters in the thrombodynamics test in the range of chronometric hypercoagulation. Conclusion: The integral thrombodynamics test for the assessment of plasma hemostasis allows for identification of hemostasis dysfunction in women taking hormonal contraceptives. To prevent the risk of thromboembolic complications, it is desirable to assess blood coagulation system parameters before administration of hormonal agents

Calculation of equivalent distributed circuit parameters of transformer winding under the influence of skin effect

Актуальность работы. При добыче, транспортировке и переработке георесурсов используется различное электротехническое оборудование, основными распределительными устройствами электроэнергии которого служат трансформаторы. В ряде случаев возникает необходимость проводить локальные электрические сети для электроэнергетической подпитки устройств переработки георесурсов, основными узлами которых также служат трансформаторы. Энергоэффективность электрических сетей зависит от состояния распределительных устройств - трансформаторов, от состояния обмоток трансформаторов. Поэтому исследование и моделирование состояний обмоток трансформатора являются важными задачами. При представлении обмоток трансформатора в виде распределенной системы необходимо знать величины элементов схемы замещения. При наличии высокочастотных токов в цепи на величину элементов схемы замещения начинает влиять скин-эффект - зависимость тока от частоты. Актуальность работы обусловлена тем, что в качестве зондирующего импульса трансформатора используют импульс наносекундной длительности, спектр которого наполнен высокими частотами. Высокие частоты зондирующего импульса провоцируют скин-эффект, который, в свою очередь, вносит в величину параметров схемы замещения зависимость от частоты. Цель работы: представить зондирующий наносекундный импульс в виде суперпозиции гармоник с различными частотами; для каждой гармоники с фиксированной частотой, входящей в формирование импульса, подсчитать индуктивность и сопротивление для схемы замещения обмотки трансформатора; для определения величин индуктивности и емкости использовать расчет электромагнитного поля с учетом скин-эффекта. Энергия рассчитанного электромагнитного поля позволяет извлечь значения индуктивности и сопротивления исследуемой системы при фиксированной частоте. Используя принцип суперпозиции, получить результирующую схему замещения, состоящую и совокупности схем, полученных для каждой частоты в отдельности. В сформированной схеме замещения обмотки трансформатора получить токи и напряжения и сравнить с экспериментальными данными. Методы исследования. Метод исследования основан на использовании принципа суперпозиции, т. е. на разложении функции в ряд Фурье по гармоническим функциям. В работе также используется численное решение уравнения в частных производных - уравнения Гельмгольца с использованием метода конечных элементов. Для реализации метода конечных элементов используется математический пакет COMSOL Multiphysics. Результаты. Произведено частотное разложение наносекундного импульса с последующим его использованием в качестве зондирующего сигнала для диагностики трансформатора. На основе решения уравнений Максвелла построена картина пространственного распределения векторного магнитного потенциала. Векторный магнитный потенциал используется для извлечения информации об индуктивности и сопротивления схемы замещения трансформаторной обмотки. Получены графические зависимости индуктивности и сопротивления схемы замещения обмотки трансформатора от частоты. Графические зависимости приведены для различных поперечных сечений обмоток трансформатора: круглой и прямоугольной. На основе полученных зависимостей построены схемы замещения обмоток трансформатора с учетом возможного влияния скин-эфекта. Приведены расчеты напряжений и тока обмоток трансформатора с использованием схемы замещения, а также результаты сравнения теоретических расчетов с экспериментальными.The relevance of the work. When producing, transporting and processing geo assets it is necessary to use various electrical equipment, the transformers are the main electricity distributors in this case. In some cases it is necessary to route the local electric network to recharge electric power devices for processing geo assets, the transformers are the main units of network as well. The efficiency of electric networks depends on the state of distribution devices - transformers, especially on the condition of the transformer windings. Therefore, the investigation and modeling of the transformer windings are the important tasks. When presenting the transformer windings as a distributed system we need to know the values of the equivalent circuit elements. In the presence of high-frequency currents in the circuit, the skin effect - the dependence of current on frequency - influences the value of equivalent circuit elements. The relevance of the research is caused by the fact that the pulse of nanosecond duration, which spectrum is filled with high frequencies, is used as the probe pulse for the transformer. The high frequency of the probe pulse provokes the skin effect, which, in its turn, contributes the frequency dependence to the value of the equivalent circuit parameters. The aim of the research is to introduce the probe nanosecond pulse as a superposition of harmonics with different frequencies; to calculate inductance and resistance for the transformer equivalent circuit for each harmonic with fixed frequency, which forms the pulse; to determine the values of inductance and capacitance using the calculation of electromagnet field and taking into account the skin effect as well. The energy of the calculated electromagnetic field allows retrieving the inductance and resistance values of the investigated system at the fixed frequency. To get the resulting equivalent circuit, which consists of combined circuits obtained for each frequency separately, using superposition principle; to obtain voltage and currents of equivalent circuit of transformer windings and compare them with the experimental data. Methods of investigation. The method of investigation is based on superposition principle, which means the expansion of arbitrary functions to the Fourier series. The authors use as well the numerical solution of partial differential equations - Helmholtz equation using the finite element method. To implement the method of finite elements the mathematical package COMSOL Multyhpisics was used. Results: The authors carried out frequency decomposition of nanosecond pulse and use it as a probe signal for transformer diagnosis. Based on the solution of Maxwell's equations the spatial distribution pattern of the magnetic vector potential was obtained. To extract the information on the inductance and resistance of the equivalent circuit of transformer winding the vector magnetic potential was used. The authors obtained the graphs of inductance and resistance of equivalent circuit for the transformer winding as a function of frequency. Graphical dependences are given for a variety of cross-sections of the transformer windings: round and rectangular shapes. Based on the obtained graphical dependencies the equivalent circuits of the transformer windings with the possible influence of the skin effect were built. The paper introduces the calculations of voltage and current of transformer windings using the equivalent circuit, as well as the results of comparison of theoretical calculations with the experimental ones