Topic Review
“Singing” Multilayer Ceramic Capacitors and Mitigation Methods
Multilayer Ceramic Capacitors (MLCC) have a major role in modern electronic devices due to their small price and size, large range of capacitance, small ESL and ESR, and good frequency response. Unfortunately, the main dielectric material used for MLCCs, Barium Titanate, makes the capacitors vibrate due to the piezoelectric and electrostrictive effects. This vibration is transferred to the PCB, making it resonate in the audible range of 20 Hz–20 kHz, and in this way the singing capacitors phenomenon occurs. This phenomenon is usually measured with a microphone, to measure the sound pressure level, or with a Laser Doppler Vibrometer (LDV), to measure the vibration. Besides this, other methods are mentioned in the literature, for example, the optical fiber and the active excitation method. There are several solutions to attenuate or even eliminate the acoustic noise caused by MLCC. Specially designed capacitors for low acoustic levels and different layout geometries are only two options found in the literature. To prevent the singing capacitor phenomenon, different simulations can be performed, the harmonic analysis being the most popular technique. 
  • 147
  • 06 Jun 2022
Topic Review
3D Placement of a New Tethered UAV
Unmanned aerial vehicles (UAVs) have become an essential component in many wireless communication systems because of their rapid deployment, mobility, and flexibility.
  • 215
  • 07 Feb 2022
Topic Review
400 kV Double-Circuit Transmission Lines
A high-voltage AC double-circuit 400 kV overhead power transmission line runs from the city of Elk (Poland) to the city of Alytus (Lithuania). This international 400 kV power transmission line is potentially one of the strongest magnetic field-generating sources in the area. This 400 kV voltage double-circuit overhead transmission line and its surroundings were analyzed using the mathematical analytical methods of superposition and reflections. This research paper includes the calculation of the numerical values of the magnetic field and its distribution. The research showed that the values of the magnetic field strength near the international 400 kV power transmission line exceed the threshold values permitted by relevant standards. This overhead power line is connected to the general (50 Hz) power system and generates a highly intense magnetic field. It is suggested that experimental trials should be undertaken in order to determine the maximum values of the magnetic field strength. For the purpose of mitigating these values, it is suggested that the height of the support bars should be increased or that any individual and commercial activities near the object under investigation should be restricted.
  • 2934
  • 20 Apr 2021
Topic Review
5G Wearable Devices
One potential way of enhancing capacity and data rates in the current and future mobile and wireless generations is the bandwidth. The data rates are directly proportional to the bandwidth. The higher bandwidth provides higher data rates. However, current frequency bands, i.e., 1.7 GHz GSM band, 1.8 GHz 4G/LTE band, 2.0 GHz 4G/LTE band, 2.1 LTE band, and 2.6 GHz band, provide limited bandwidth. Recently, high-frequency bands including 24 GHz (n258), 28 GHz (n257 and n261), 37 GHz (n260), and 39 GHz (n260) in addition to some future recommended bands, i.e., 47 and 60 GHz, have been considered for 5G applications.
  • 239
  • 11 Jan 2022
Topic Review
6G Enabled Smart Infrastructure
6G is expected to have data rates in the order of terabits per second and a latency of less than 1ms. It is expected to drive the Internet of Everything, with 10,000,000 connections per square km.
  • 990
  • 20 Apr 2021
Topic Review
A Light-Electric-Vehicle Batteries Maintenance Tool
This work proposes an open-hardware low-cost battery maintenance tool architecture that can be used with common laboratory instruments. The tool is based on a relay matrix and a battery monitor integrated circuit. It is able to completely characterize and optimize the state of a battery independently of the battery management system and also gives a figure of the individual aging of the battery cells. The work shows the architecture and the experimental validation of a 16-cells battery maintenance tool prototype. The results demonstrate that utilizing the tool brings the battery to the best possible state and identifies the degradation of the cells in terms of capacity and resistance.
  • 119
  • 12 Nov 2021
Topic Review
A New Parcel Delivery System
This entry proposes a novel parcel delivery system which consists of a drone and public transportation vehicles such as trains, trams, etc. This system involves two delivery schemes: drone-direct scheme referring to delivering to a customer by a drone directly and drone–vehicle collaborating scheme referring to delivering a customer based on the collaboration of a drone and public transportation vehicles. The fundamental characteristics including the delivery time, energy consumption and battery recharging are modelled, based on which a time-dependent scheduling problem for a single drone is formulated. It is shown to be NP-complete and a dynamic programming-based exact algorithm is presented. Since its computational complexity is exponential with respect to the number of customers, a sub-optimal algorithm is further developed. This algorithm accounts the time for delivery and recharging, and it first schedules the customer which leads to the earliest return.
  • 388
  • 01 Nov 2020
Topic Review
A Reactive Power Compensation Method
One of the main challenges of today’s electrical power engineering is the symmetrization of grid voltages and the minimization of reactive power flows in distribution networks. There are many negative effects associated with asymmetry in power systems, such as increased losses in electric motors, harmonics transferred to DC systems, or phase currents inequality. With the reactive power compensation method, the active power flow can be reduced even in the presence of angular asymmetry between voltage vectors of the utility grid. 
  • 241
  • 09 Feb 2022
Topic Review Peer Reviewed
A Review of SATis5: Perspectives on Commercial and Defense 5G SATCOM Integration
This review provides a comprehensive review of past and existing works on 5G systems with a laser focus on 5G Satellite Integration (SATis5) for commercial and defense applications. The holistic survey approach is used to gain an in-depth understanding of 5G-Terrestrial Network (5G-TN), 5G-Non-Terrestrial Network (5G-NTN), SATis5 testbeds, and projects along with related SATis5 architectures. Based on the survey results, the review provides (i) outlook perspectives on potential SATis5 architectures for current and future integrated defense and commercial satellite communication (SATCOM) with 5G systems, and (ii) a thorough understanding of problems associated with anticipated outlooks and corresponding studies addressing these problems. The commercial SATis5 architectures discussed here can be extended to civilian SATCOM applications.
  • 38
  • 26 Sep 2022
Topic Review
Abnormal Operating Conditions of Oil-Immersed Large Power Transformers
Large power transformers (LPT) are custom-built pieces of equipment that are crucial links to the bulk transmission grid. Usually, they link a generator-transmission line and/or linking lines of different voltages. It is essential for large power transformers to understand which condition of their components indicates an abnormal operation.
  • 145
  • 12 Jul 2022
  • Page
  • of
  • 47
Top
Feedback