Bulletin of NTU "KhPI". Series: Problems of Electrical Machines and Apparatus Perfection. The Theory and Practice / Вісник Національного технічного університету "ХПІ". Серія: Проблеми удосконалювання електричних машин і апаратів. Теорія і практика
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Do Diversity and Context Collapse Kill an Online Social Network?
No full textOur social lives are segmented into various social circles, including family, friends, and colleagues. Differences in social norms and expectations between these circles can create tension for us, especially in large online social networks (OSNs), where these circles are jointly present, and their boundaries are blurred. It is unclear whether this phenomenon, called context collapse, outweighs the social convenience of having access to diverse communities in one place. To better understand this trade-off, we analyze whether ego network characteristics suggestive of context collapse can explain exit from iWiW, a now-defunct Hungarian OSN with over 3.5 million active users at its peak. We measure a person’s exposure to context collapse with the presence of two conditions: the first is that communities of the user are non-overlapping, while the second is that these communities are different from each other. We find that users with fragmented social networks indeed leave the platform earlier, if these distinct communities differ significantly in their age profiles and urban-rural composition. However, the highest probability for leaving was present among those with non-fragmented networks including similar communities. These seemingly contradicting results are caused by the process that network fragmentation itself decreases the probability of leaving. Thus, our results demonstrate simultaneously how brokerage can be valuable and context collapse stressful for users of OSNs
Null Regions: A Unified Conceptual Framework for Statistical Inference
No full textRuling out the possibility that there is absolutely no effect or association between variables may be a good first step, but it is rarely the ultimate goal of science. Yet that is the only inference provided by traditional null hypothesis significance testing (NHST), which has been a mainstay of many scientific fields. Reliance on NHST also makes it difficult to define what it means to replicate a finding, and leads to an uncomfortable quandary in which increasing precision in data reduces researchers' ability to perform theory falsification. To solve these problems, in recent years several alternatives to traditional NHST have been proposed. However, each new test is described using its own terminology and practiced in different fields. We describe a simple, unified framework for conceptualizing all these tests so that it is not necessary to learn them separately. Moreover, the framework allows researchers to conduct any of these tests by asking just one question: is the confidence interval entirely outside the null region(s)? This framework may also help researchers choose the test(s) that best answers their research question when simply ruling out ‘no effect at all’ is not enough
Black (Gifted) Joy: A Critical Race Theory Perspective
No full textThis article presents a theoretical question: what is giftedness, but an expression of Black joy? This is presented with relevant real-world examples and #BlackVoices through youth poetry. The framework of critical race theory is used as a lens, to situate the world in which Black joy is found. The author argues that this manifestation, situated within the structural racism ever present in the system of education, has the unfortunate impact of igniting educators’ anti-blackness, resulting in the missingness (Gentry et al., 2019) of gifted Black students from gifted programs and services. The author delves into constructs of white supremacy, white rage, and antiblackness as the foundational concepts that contribute to this missingness, using research and more youth poetry to substantiate the claims. #BlackVoices are featured throughout, as emic perspectives, giving voice, heart, soul, and joy to the research, the words on the page
Динамічна модель магнітної передачі
Get PDFIn the work, a non-contact electromechanical energy converter with permanent magnets, which is known as magnetic transmission, is studied. Magnetic transmissions have certain structural advantages compared to mechanical transmissions, namely: high reliability, efficiency, lower losses, non-contact transmission of mechanical power, no maintenance costs, and simplicity of construction. The use of magnetic transmissions for systems of conversion of low-potential mechanical energy into electrical energy is especially relevant: wind energy, water energy, energy of mechanical vibrations, etc. The use of magnetic gearboxes in autonomous wind power plants can be more promising from an economic and technical point of view compared to traditional mechanical transmissions. A numerical simulation mathematical model of magnetic transmission with permanent magnets has been developed. The use of magnetic transmission, for example, for autonomous wind power systems allows to increase the reliability of the operation of such installations, reduce operating costs and increase the efficiency of their operation. In emergency modes of operation, the use of magnetic transmission allows to avoid destruction or emergency shutdowns of electrical equipment. The developed simulation model of magnetic transmission takes into account the pulsations of the electromagnetic moment due to the discrete structure of the magnetic transmission and the change of the model parameters when the input moment changes: pulsations, losses in the magnetic core and permanent magnets, the change of the load angle and the transmitted electromagnetic moment. A feature of the developed model of the magnetic transmission system is that a change in the load of the electric power source leads to a change in the operating point on the mechanical characteristics of the rotor of the wind turbine. Conversely, when the wind parameters change, the output parameters of the source of electrical energy change: power, voltage, current and electromagnetic moment.В роботі проведено дослідження безконтактного електромеханічного перетворювача енергії із постійними магнітами, що відомий як магнітна передача. Магнітні передачі мають певні конструктивні переваги порівняно із механічними передачами, а саме: висока надійність, ефективність, менші втрати, безконтактна передача механічної потужності, відсутність витрат на технічне обслуговування, простота конструкції. Особливо актуальним є використання магнітних передач для систем перетворення низькопотенційної механічної енергії в електричну: енергія вітру, енергія води, енергія механічних коливань і т.ін. Застосування магнітних редукторів в автономних вітрових електростанціях може бути більш перспективним з економічної та технічної точок зору порівняно з традиційними механічними передачами. Розроблено чисельну імітаційну математичну модель магнітної передачі із постійними магнітами. Використання магнітної передачі, наприклад, для автономних вітроелектричних систем дозволяє підвищити надійність роботи таких установок, зменшити експлуатаційні витрати та підвищити ефективність їх роботи. В аварійних режимах роботи використання магнітної передачі дозволяє уникнути руйнувань або аварійних зупинок роботи електрообладнання. Розроблена імітаційна модель магнітної передачі враховує пульсації електромагнітного моменту через дискретну структуру магнітної передачі та зміну параметрів моделі при зміні вхідного моменту: пульсацій, втрат в магнітному осерді та постійних магнітах, зміну кута навантаження та передавального електромагнітного моменту. Особливістю розробленої моделі системи магнітної передачі є те, що зміна навантаження електроджерела електричної енергії а призводить до зміни робочої точки на механічній характеристиці ротора вітроустановки. І навпаки, при зміні параметрів вітру змінюються вихідні параметри джерела електричної енергії: потужність, напруга, струм та електромагнітний момент
Шляхи подолання бар'єру при переході асинхронних двигунів до класу енергоефективності IE5
Get PDFPurpose. To provide a comprehensive analytical review on ways to increase the energy efficiency of induction motors and identify those suitable for transitioning fixed speed induction motors to IE5 level. Methodology. A thorough study of research and development in the field of increasing the energy efficiency of induction motors for various purposes was conducted. The experience of the development of traction induction motors of electric vehicles as dynamically developing is extrapolated. Results. It was established that the main limiting factor in increasing the energy efficiency of induction motors to the IE5 level is its thermal state. Analysis of ways to improve the efficiency of induction motors indicates the need for their complex application. It is most expedient to optimize and improve the elements of the air-cooling system of induction motors. To carry out the research, it is necessary to comprehensively apply electromagnetic and temperature field modeling systems of induction motors. Given certain shortcomings of thermal models of induction motors, it is necessary to combine modeling with experimental studies using both classical temperature sensors and the method of thermography. Originality. The combination of modern methods of modeling the thermal state of induction motors and experimental studies makes it possible to determine reserves for increasing the efficiency of existing motors. Using these results, it is possible to improve induction motors to the IE5 efficiency level. Practical value. Manufacturers and researchers see difficulties with the transition of induction motors of industrial purpose to the IE5 efficiency level, so they focused their attention on synchronous electric motors. The results of our research prove that, despite certain barriers, this transition can be made, albeit with certain difficulties.Застосування енергоефективних електродвигунів у промисловості дозволяє більш раціонально використовувати енергетичні ресурси і скоротити викиди парникових газів. Зважаючи на те, що у промисловості переважно використовуються асинхронні двигуни із фіксованою частотою обертання, завдання підвищення їхньої енергоефективності є актуальним. Встановлено, що головним обмежувальним фактором підвищення енергоефективності асинхронних двигунів до рівня IE5, є його тепловий стан. Аналіз шляхів підвищення ефективності асинхронних двигунів вказує на необхідність їх комплексного застосування. Найбільш доцільним є проведення оптимізації та удосконалення елементів системи повітряного охолодження асинхронних двигунів. Для проведення дослідження потрібно комплексно застосовувати системи моделювання електромагнітного та температурного поля асинхронних двигунів. Враховуючи певні недоліки теплових моделей асинхронних двигунів необхідно поєднувати моделювання із експериментальними дослідженнями як за допомогою класичних датчиків температури, так і методу термографії
Оцінка стану умов праці виробничої системи
Get PDFThe paper analyzes methods for assessing professional risk, emphasizing that the primary method is job certification. Job certification establishes the compliance of the workplace with regulatory characteristics for specific risk factors in the production environment. The analysis reveals that the existing methodology for job certification does not provide insights into changes in the parameters of hazardous and harmful factors in the production environment, and consequently, changes in working conditions between planned certifications. The study advocates for a comprehensive assessment of the collective impact of all factors in the production environment and work processes on the human body. This is achieved through hygienic risk factor assessment. The paper highlights the appropriateness of quantitatively assessing working conditions in points, considering the simultaneous influence of multiple hazardous factors. A procedure for point-based assessment of working conditions is proposed, and the applicability of Haber's Law to determine the cumulative dose of a harmful factor in the body is demonstrated.В роботі проведений аналіз методів оцінки професійного ризику. Показано, що основним методом є атестація робочих місць, за допомогою якої встановлюється відповідність виробничого середовища її нормативним характеристикам за окремими факторами ризику. Аналіз показав, що існуюча методика атестації робочих місць не дозволяє судити про зміну параметрів небезпечних та шкідливих факторів виробничого середовища, а відповідно, і про зміну умов праці в період між плановими атестаціями. Показано, що основним методом оцінки професійного ризику є комплексна оцінка сукупного впливу всіх факторів виробничого середовища і трудового процесу на організм людини за допомогою гігієнічної оцінки факторів ризику. Показано доцільність кількісної оцінки умов праці в балах при одночасному впливі багатьох небезпечних та шкідливих факторів. Запропонована процедура бального оцінювання умов праці. Показана доцільність застосування закону Хабера для визначення накопиченої дози шкідливого фактору в організмі
The New "Good Samaritans": Digital Helpers During Pandemic Times in Canada
No full textDuring times of crises such as the present COVID-19 pandemic in Canada, digital helpers emerge as key agents of the promotion of digital literacy in society. Using data from the CPSS-5 national survey, the authors looked at the digital help provided by individuals to various demographic cohorts during the pandemic period in Canada. This survey comprised 3,961 adult respondents aged 15 years old who were interviewed in September, 2020. Digital helpers assisted fellow Canadians in through navigating digital technologies such as videoconferencing, online voice chats, online shopping sites or educational resources. Digital helpers comprised 48% of the total adult population where the most typical form was the assistance of adult respondents aged 18 to 64 years old. Assistance to specific demographic cohorts such as children, teens and seniors varied according to the socio-demographic profiles of helpers. Multivariate analysis of seven typical types of digital help suggests that the likelihood of digital help increased with a younger age of the helper, the presence of a child living at home, university education, urban residence status and/or living in large households. Overall, digital help outcomes appeared to be linked to the life course position of the individual and the types of family or non family networks situated around the helper. The role of young married women living with children and other individuals as the new "Good Samaritans" of digital help is relevant in this regard
Thinking about God Discourages Dehumanization of Religious Outgroups
No full textIn seven studies, six with American Christians and one with Israeli Jews (total N = 2,323), we systematically examine how and when belief in moralizing gods influences dehumanization of ethno-religious outgroups. We focus on dehumanization because it is a key feature of intergroup conflict. In Studies 1-6, participants completed measures of dehumanization from their own perspectives and also from the perspective of God, rating the groups’ humanity as they thought God would rate it, or wish for them to rate it. When participants completed measures from both their own and God’s perspectives, they reported believing that, compared with their own views, God would see (or prefer for them to see) outgroup members as more human. In Study 7, we extend these findings by demonstrating that thinking about God’s views reduces the extent to which religious believers personally dehumanize outgroup members. Collectively, results demonstrate that religious believers attribute universalizing moral attitudes to God, compared to themselves, and document how thinking about God’s views can promote more positive intergroup attitudes
Please don’t stop the music: A meta-analysis of the cognitive and academic benefits of instrumental musical training in childhood and adolescence
No full textAn extensive literature has investigated the impact of musical training on cognition and academic achievement in children and adolescents. However, most of the studies have relied on cross-sectional designs, which makes it impossible to elucidate whether the observed differences are a consequence of the engagement in musical activities. Previous meta-analyses with longitudinal studies have also found inconsistent results, possibly due to their reliance on vague definitions of musical training. In addition, more evidence has appeared in recent years. The current meta-analysis investigates the impact of early programs that involve learning to play musical instruments on cognitive and academic skills, as previous meta-analyses have not focused on this form of musical training. Following a systematic search, 34 independent samples of children and adolescents were included. All the studies had pre-post designs and, at least, one control group. Overall, we found a small but significant benefit (g = 0.24) with short-term programs, regardless of whether they were randomized or not. In addition, a small advantage at baseline was observed in studies with self-selection (g = 0.28), indicating that participants who had the opportunity to select the activity consistently showed a slightly superior performance prior to the beginning of the intervention. Our findings support a nature and nurture approach to the relationship between instrumental training and cognitive performance. Nevertheless, evidence from well-conducted studies is still scarce and more studies are necessary to reach firmer conclusions
Population ethical intuitions
No full textIs humanity worthwhile? And where should the human species be headed in the future? In part, the answers to these questions require us to morally evaluate the (potential) human population in terms of its size and aggregate welfare. This assessment lies at the heart of population ethics. Our investigation across nine experiments (N = 5,776) aimed to answer three questions about how lay people aggregate welfare across people: (1) Do they weigh happiness and suffering symmetrically?; (2) Do they focus more on the average or total welfare of a given population?; and (3) Do they account only for currently existing lives, or also lives that could yet exist? We found that, first, participants believed that more happy than unhappy people were needed in order for the whole population to be net positive (Studies 1a-c). Second, participants had a preference both for populations with greater total and greater average welfare each (Study 3a-d). Their focus on average welfare even led them (remarkably) to judge it preferable to add new suffering people to an already miserable world, as long as this increased average welfare. But, when prompted to reflect, participants’ preference for the population with the better total welfare became stronger. Third, participants did not consider the creation of new people as morally neutral. Instead, they viewed it as good to create new happy people and as bad to create new unhappy people (Studies 2a-b). Our findings have implications for moral psychology, philosophy and global priority setting