RESUMEN
Sensors based on chaotic oscillators have a simple design, combined with high sensitivity and energy efficiency. Among many developed schemes of such sensors, the promising one is based on the Duffing oscillator, which possesses a remarkable property of demonstrating chaotic oscillations only in the presence of a weak sine wave at the input. The main goal of this research was to evaluate the maximal sensitivity of a practically implemented metal detector based on the Duffing oscillator and compare its sensitivity with conventional sensors. To achieve high efficiency of the Duffing-based design, we proposed an algorithm which performs a bifurcation analysis of any chaotic system, classifies the oscillation modes and determines the system sensitivity to a change in different parameters. We apply the developed algorithm to improve the sensitivity of the electronic circuit implementing the Duffing oscillator, serving as a key part of a three-coil metal detector. We show that the developed design allows detecting the presence of metal objects near the coils more reliably than the conventional signal analysis techniques, and the developed detector is capable of sensing a large metal plate at distances up to 2.8 of the coil diameter, which can be considered a state-of-the-art result.
RESUMEN
Abstract This study aims to measure the time allocated to child raising using parents' self-assessment and the criterion of subjective time sufficiency or insufficiency. We surveyed 545 Russian parents from the Ural region and used factor analysis to identify the main determinants that affect the self-assessment of time allocated to parenting. We found that parents in the Russian Ural region believe they do not spend enough time with their children. Reasons for the insufficient amount of time allocated to parenting are the following: overload of labor duties at home and at work, psychological causes of intergenerational interaction, external reasons − studies, poor health, the need to care for other relatives and so on.
Resumo Este estudo tenta medir o tempo alocado aos filhos por meio da autoavaliação dos pais e do critério de suficiência subjetiva ou tempo insuficiente. Foram pesquisados 545 pais russos da região dos Urais e utilizou-se a análise fatorial para identificar os principais determinantes que afetam a autoavaliação do tempo alocado pelos pais. Verificou-se que os pais nas regiões russas dos Urais têm uma opinião comum de que não passam tempo suficiente com seus filhos. As razões para o tempo insuficiente alocado à educação dos filhos são as seguintes: sobrecarga de tarefas em casa e no trabalho; causas psicológicas de interação intergeracional; e razões externas, como estudo, saúde precária e necessidade de cuidar de outros parentes.
Resumen Este estudio intenta medir el tiempo asignado a los niños por medio de la autoevaluación de los padres y del criterio de suficiencia subjetiva o de insuficiencia de tiempo. Se encuestaron 545 padres rusos de la región de los Urales y se usó el análisis factorial para identificar los principales determinantes que afectan la autoevaluación del tiempo asignado a la crianza de los hijos. Descubrimos que en las regiones rusas los padres tienen la opinión común de que no pasan suficiente tiempo con sus hijos. Las razones para la cantidad insuficiente de tiempo asignado a la crianza de los hijos son la sobrecarga de deberes laborales en el hogar y en el trabajo, causas psicológicas de la interacción intergeneracional, o razones externas como estudio, mala salud o necesidad de cuidar a otros familiares.
