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1 – 10 of 41Erol Can and Ugur Kilic
Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high…
Abstract
Purpose
Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion.
Design/methodology/approach
After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads.
Findings
According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency.
Practical implications
FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft.
Social implications
Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment.
Originality/value
The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.
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Sami Barmada, Nunzia Fontana, Leonardo Sandrolini and Mattia Simonazzi
The purpose of this paper is to gain a better understanding on how metasurfaces behave, in terms of currents in each unit cell. A better knowledge of their behavior could lead to…
Abstract
Purpose
The purpose of this paper is to gain a better understanding on how metasurfaces behave, in terms of currents in each unit cell. A better knowledge of their behavior could lead to an ad-hoc design for specific applications.
Design/methodology/approach
The methodology used is both theoretical and numerical; it is based on circuit theory and on an optimization procedure.
Findings
The results show that when the knowledge of the current in each unit cell of a metasurface is needed, the most common approximations currently used are often not accurate. Furthermore, a procedure for the termination of a metasurface, with application-driven goals, is given.
Originality/value
This paper investigates the distribution of the currents in a 2D metamaterial realized with magnetically coupled resonant coils. Different models for the analysis of these structures are illustrated, and the effects of the approximations they introduce on the current values are shown and discussed. Furthermore, proper terminations of the resonators on the boundaries have been investigated by implementing a numerical optimization procedure with the purpose of achieving a uniform distribution of the resonator currents. The results show that the behavior of a metasurface (in terms of currents in each single resonator) depends on different properties; as a consequence, their design is not a trivial task and is dependent on the specific applications they are designed for. A design strategy, with lumped impedance termination, is here proposed.
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Jinwei Zhao, Shuolei Feng, Xiaodong Cao and Haopei Zheng
This paper aims to concentrate on recent innovations in flexible wearable sensor technology tailored for monitoring vital signals within the contexts of wearable sensors and…
Abstract
Purpose
This paper aims to concentrate on recent innovations in flexible wearable sensor technology tailored for monitoring vital signals within the contexts of wearable sensors and systems developed specifically for monitoring health and fitness metrics.
Design/methodology/approach
In recent decades, wearable sensors for monitoring vital signals in sports and health have advanced greatly. Vital signals include electrocardiogram, electroencephalogram, electromyography, inertial data, body motions, cardiac rate and bodily fluids like blood and sweating, making them a good choice for sensing devices.
Findings
This report reviewed reputable journal articles on wearable sensors for vital signal monitoring, focusing on multimode and integrated multi-dimensional capabilities like structure, accuracy and nature of the devices, which may offer a more versatile and comprehensive solution.
Originality/value
The paper provides essential information on the present obstacles and challenges in this domain and provide a glimpse into the future directions of wearable sensors for the detection of these crucial signals. Importantly, it is evident that the integration of modern fabricating techniques, stretchable electronic devices, the Internet of Things and the application of artificial intelligence algorithms has significantly improved the capacity to efficiently monitor and leverage these signals for human health monitoring, including disease prediction.
The study examines the prevalence and correlates of perceived discrimination across ten Asian American ethnic groups. The goal is to disaggregate an artificially created broad…
Abstract
Purpose
The study examines the prevalence and correlates of perceived discrimination across ten Asian American ethnic groups. The goal is to disaggregate an artificially created broad categorization of Asians into subgroups to reveal the existing intragroup differences.
Design/methodology/approach
Bivariate and multivariate analyses were based on data from the 2016 National Asian American Survey (NAAS). The exclusion of missing data on all variables used in the analysis revealed a final analytical sample size of 4,276.
Findings
Compared to all other Asian American ethnic groups, Cambodians report the lowest frequency of perceived discrimination on all outcome measures. On the contrary, the prevalence of perceived discrimination is highest for Bangladeshis and Indians on lifetime and job-related discrimination and for Indians and Japanese on day-to-day discrimination. Nearly all Asian American ethnic groups are more likely to report one or more types of perceived discrimination than Chinese Americans. The observed relationships disappear for Cambodians, Pakistanis and Japanese but persist for Bangladeshis, Filipinos, Hmong and Indians after controlling for socio-demographic characteristics. Among the socio-demographic controls, gender, birthplace, education and employment status are found to be significant predictors of perceived discrimination.
Originality/value
The findings of the study further the discussion on the importance of disaggregating minority groups and considering their heterogeneous experiences of perceptions of discrimination in the United States.
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Meng Wang, Yongheng Li, Yanyan Shi and Fenglan Huang
With the development of artificial intelligence, proximity sensors show their great potential in intelligent perception. This paper aims to propose a new planar capacitive sensor…
Abstract
Purpose
With the development of artificial intelligence, proximity sensors show their great potential in intelligent perception. This paper aims to propose a new planar capacitive sensor for the proximity sensing of a conductor.
Design/methodology/approach
Different from traditional structures, the proposed sensor is characterized by sawtooth-structured electrodes. A series of numerical simulations have been carried out to study the impact of different geometrical parameters such as the width of the main trunk, the width of the sawtooth and the number of sawtooths. In addition, the impact of the lateral offset of the approaching graphite block is investigated.
Findings
It is found that sensitivity is improved with the increase of the main trunk with, sawtooth width and sawtooth number while a larger lateral offset leads to a decrease in sensitivity. The performance of the proposed planar capacitive proximity sensor is also compared with two conventional planar capacitive sensors. The results show that the proposed planar capacitive sensor is obviously more sensitive than the two conventional planar capacitive sensors.
Originality/value
In this paper, a new planar capacitive sensor is proposed for the proximity sensing of a conductor. The results show that the capacitive sensor with the novel structure is obviously more sensitive than the traditional structures in the detection of the proximity conductor.
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Yanmin Zhou, Zheng Yan, Ye Yang, Zhipeng Wang, Ping Lu, Philip F. Yuan and Bin He
Vision, audition, olfactory, tactile and taste are five important senses that human uses to interact with the real world. As facing more and more complex environments, a sensing…
Abstract
Purpose
Vision, audition, olfactory, tactile and taste are five important senses that human uses to interact with the real world. As facing more and more complex environments, a sensing system is essential for intelligent robots with various types of sensors. To mimic human-like abilities, sensors similar to human perception capabilities are indispensable. However, most research only concentrated on analyzing literature on single-modal sensors and their robotics application.
Design/methodology/approach
This study presents a systematic review of five bioinspired senses, especially considering a brief introduction of multimodal sensing applications and predicting current trends and future directions of this field, which may have continuous enlightenments.
Findings
This review shows that bioinspired sensors can enable robots to better understand the environment, and multiple sensor combinations can support the robot’s ability to behave intelligently.
Originality/value
The review starts with a brief survey of the biological sensing mechanisms of the five senses, which are followed by their bioinspired electronic counterparts. Their applications in the robots are then reviewed as another emphasis, covering the main application scopes of localization and navigation, objection identification, dexterous manipulation, compliant interaction and so on. Finally, the trends, difficulties and challenges of this research were discussed to help guide future research on intelligent robot sensors.
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The aim of this review is to present together the studies on textile-based moisture sensors developed using innovative technologies in recent years.
Abstract
Purpose
The aim of this review is to present together the studies on textile-based moisture sensors developed using innovative technologies in recent years.
Design/methodology/approach
The integration levels of the sensors studied with the textile materials are changing. Some research teams have used a combination of printing and textile technologies to produce sensors, while a group of researchers have used traditional technologies such as weaving and embroidery. Others have taken advantage of new technologies such as electro-spinning, polymerization and other techniques. In this way, they tried to combine the good working efficiency of the sensors and the flexibility of the textile. All these approaches are presented in this article.
Findings
The presentation of the latest technologies used to develop textile sensors together will give researchers an idea about new studies that can be done on highly sensitive and efficient textile-based moisture sensor systems.
Originality/value
In this paper humidity sensors have been explained in terms of measuring principle as capacitive and resistive. Then, studies conducted in the last 20 years on the textile-based humidity sensors have been presented in detail. This is a comprehensive review study that presents the latest developments together in this area for researchers.
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The purpose of this commentary is discuss how musical intervention and imagined interactions can be used to deal with conflict. Music has been called the universal language…
Abstract
Purpose
The purpose of this commentary is discuss how musical intervention and imagined interactions can be used to deal with conflict. Music has been called the universal language because of its tonality and rhythm. It affects conflict and aggression and helps people to deal with stress. Research is reviewed showing physiological arousal with background music. The effects of music on aggression are summarized in terms of emotional regulation, catharsis and empathy, and the use of mental imagery in the form of imagined interactions, including relational maintenance catharsis and conflict linkage, is discussed. The incremental sound organizer (ISO) principle of music therapy is discussed as a mechanism to affect emotions while listening to music. Finally, a tool to measure the emotional effect of music on listeners is discussed in terms of the musical mood wheel.
Design/methodology/approach
This is a commentary on the effects of background music on reducing aggression.
Findings
Music can reduce aggression, depending on how it is used. Music affects how we manage our emotions, reduces stress, provides catharsis and can be a distracting element. Music can enhance empathic feeling; induce positive moods, social bonding, physiological changes and neurobiological changes; and affect our arousal.
Research limitations/implications
Music therapy and musical intervention can be applied to conflict resolution.
Practical implications
The ISO principle of music therapy is designed to deal with changing a person’s emotions as they listen to a medley of music. The mood of the person is measured using a series of scales reflecting a continuum of sadness to happiness, and the music is designed to match the mood of the patient to the music being played and/or listened to, which in turn fosters the achievement of an altered state of consciousness. For example, if you are angry, start with music that is loud and gradually switch to a more tranquil piece of music. “The vectoring power of music is that we change the mood or emotion of persons from one affective pole (joy) to its opposite (anger) through small incremental changes in the rhythm and intensity of the music” (Honeycutt, 2003, p. 82).
Social implications
Background music in music psychology literature is often referred to as musical intervention. Background music can help us recall positive and negative scenes as the music triggers endorphins in the brain (Salimpoor et al., 2011). Background music is intended to enhance the surrounding context without drawing significant attention. It is often played in spaces such as restaurants, stores, offices or public places to create a certain mood or ambiance.
Originality/value
It is important to note that the effectiveness of musical intervention in reducing aggression can vary based on individual preferences, the specific type of music used, and the context in which it is applied. Additionally, while music intervention can play a role in aggression reduction, it is often most effective when used as part of a comprehensive therapeutic approach.
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Andreas Gschwentner, Manfred Kaltenbacher, Barbara Kaltenbacher and Klaus Roppert
Performing accurate numerical simulations of electrical drives, the precise knowledge of the local magnetic material properties is of utmost importance. Due to the various…
Abstract
Purpose
Performing accurate numerical simulations of electrical drives, the precise knowledge of the local magnetic material properties is of utmost importance. Due to the various manufacturing steps, e.g. heat treatment or cutting techniques, the magnetic material properties can strongly vary locally, and the assumption of homogenized global material parameters is no longer feasible. This paper aims to present the general methodology and two different solution strategies for determining the local magnetic material properties using reference and simulation data.
Design/methodology/approach
The general methodology combines methods based on measurement, numerical simulation and solving an inverse problem. Therefore, a sensor-actuator system is used to characterize electrical steel sheets locally. Based on the measurement data and results from the finite element simulation, the inverse problem is solved with two different solution strategies. The first one is a quasi Newton method (QNM) using Broyden's update formula to approximate the Jacobian and the second is an adjoint method. For comparison of both methods regarding convergence and efficiency, an artificial example with a linear material model is considered.
Findings
The QNM and the adjoint method show similar convergence behavior for two different cutting-edge effects. Furthermore, considering a priori information improved the convergence rate. However, no impact on the stability and the remaining error is observed.
Originality/value
The presented methodology enables a fast and simple determination of the local magnetic material properties of electrical steel sheets without the need for a large number of samples or special preparation procedures.
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