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Topic Review
Distributed Element Circuit
Distributed element circuits are electrical circuits composed of lengths of transmission lines or other distributed components. These circuits perform the same functions as conventional circuits composed of passive components such as capacitors, inductors, and transformers. They are used mostly at microwave frequencies where conventional components are difficult or impossible to implement. A major advantage of distributed element circuits is that they can be produced cheaply as a printed circuit board for consumer products such as satellite television. They are also made in coaxial and waveguide formats for applications such as radar, satellite communication, and microwave links. A phenomenon that is much used in distributed element circuits is that a length of transmission line can be made to behave as a resonator. Distributed element components that do this include stubs, coupled lines, and cascaded lines. Circuits built from these components include filters, power dividers, directional couplers, and circulators. Distributed element circuits were investigated in the 1920s and 1930s but did not become important until World War II when they were used in radar. After the war their use was at first limited to military, space, and broadcasting infrastructure use but improvements in materials science in the field soon led to wider applications.
  • 2.2K
  • 17 Oct 2022
Topic Review
Electric Vehicles
E-mobility sustainability assessment is becoming more comprehensive with research integrating social aspects without focusing only on technical, economic, and/or environmental perspectives. The transportation sector is indeed one of the leading and most challenging greenhouse-gas polluters, and e-mobility is seen as one of the potential solutions; however, a social perspective must be further investigated to improve the perception of and acceptance of electric vehicles. 
  • 2.2K
  • 04 Feb 2021
Topic Review
Range Extender (Vehicle)
A range extender vehicle is a battery electric vehicle that includes an auxiliary power unit (APU) known as a 'range extender'. The range extender drives an electric generator which charges a battery which supplies the vehicle's electric motor with electricity. This arrangement is known as a series hybrid drivetrain. The most commonly used range extenders are internal combustion engines, but fuel-cells or other engine types can be used. Range extender vehicles are also referred to as extended-range electric vehicles (EREV), range-extended electric vehicles (REEV), and range-extended battery-electric vehicle (BEVx) by the California Air Resources Board (CARB). The key function of the range extender is to increase the vehicle's range. Range autonomy is one of the main barriers for the commercial success of electric vehicles, and extending the vehicle's range when the battery is depleted helps alleviate range anxiety. A range extending vehicle design can also reduce the consumption of the range extending fuel (such as gasoline) by using the primary fuel (such as battery power), while still maintaining the driving range of a single fuel vehicle powered by a range extending fuel such as gasoline. The range extending fuel is generally considered to be less environmentally and economically friendly to use than the primary fuel source, so the vehicle control system gives preference to using the primary fuel if it's available. However, due to range limitations with the primary fuel source, the range extending fuel allows the vehicle to get many of the cost and environmental benefits of the primary fuel, while maintaining the full driving range of the range extending fuel source. For example, in the Chevy Volt, battery power from the electric grid can be cheaper and more environmentally sustainable than burning gasoline (depending on the electric generation source), but due to the trade offs between the range of a pure electric vehicle and its battery size, adding the range extending gasoline is considered by many to be good compromise to give the Chevy Volt a significantly greater driving range. How many benefits are derived from using the primary fuel however depend on how the vehicles are driven. For example, a first generation Chevy Volt will operate 100% on battery power from the electric grid for the first 60 km (37 miles), while the second generation Volt will operate on 100% battery power for the first 85 km (53 miles) when fully recharged between trips. However, if the same Chevy Volt is driven for hundreds of miles a day it will require significant gasoline as the battery will be quickly depleted. Using the gasoline engine to generate power for the motors, the economy ratings are 6.4 L/100 km (37 mpg‑US) and 5.6 L/100 km (42 mpg‑US) for the different generation models. Therefore, it is critical to understand the driving patterns of the average commuter to fully understand the impact these range extending vehicles will have in the real world. Many range extender vehicles, including the Chevrolet Volt and the BMW i3, are able to charge their batteries from the grid as well as from the range extender, and therefore are a type of plug-in hybrid electric vehicle (PHEV). When a range extender uses conventional fuels they can re-fuel at regular fuel stations, which provides them with a similar driving range to conventional automobiles. As an REEV is only propelled by the electric motor it can do away with the weight and cost associated with the gearbox transmission system typically used in internal combustion engine cars. Further, as the range extender does not need to increase or decrease output in line with the power needs of the vehicle (this task is handled by the electric motor) the range extender can be sized to satisfy the vehicle's average power requirement rather than its peak power requirement (such as when accelerating). The range extender can also operate much closer to its most efficient rotational speed. These design features allow an REEV to convert fossil fuel energy to electric power and vehicle motion very efficiently.
  • 2.2K
  • 28 Oct 2022
Topic Review
Solid State Transformers in Distribution System
Solid State Transformer (SST) is considered to be the most suitable and appropriate conversion device to replace the traditional prevailing transformer. In this device, the weight/volume savings, extensive efficiency enhancement and above all, the cost economization are taken to be the hallmarks. SST configuration comprises of three main stages (i.e., a rectifier, isolation through the HF transformer and finally the DC-AC converter to reproduce line frequency AC).
  • 2.2K
  • 01 Dec 2022
Topic Review
Optical Sensors for Oil/Gas Applications
The sensing requirements of the Oil & Gas industry for improved sensing in deeper zones include increased transmission length, improved spatial coverage and integration of multiple sensors with multimodal sensing capability. This imposes problems like signal attenuation, crosstalks and cross sensitivities. Optical fibre-based sensors are expected to provide superior sensing capabilities compared to traditional electrical sensors. 
  • 2.2K
  • 26 Sep 2021
Topic Review
SiC Trench MOSFETs’ Reliability under Short-Circuit Conditions
MOSFETs exhibit different failure modes at different DC bus voltages.  For double trench SiC MOSFETs, the failure modes are gate fault at lower DC bus voltage and thermal runaway at higher DC bus voltage, while the failure modes for asymmetric trench SiC MOSFETs are soft failure and thermal runaway, respectively.  The short-circuit withstand time (SCWT) of the asymmetric trench MOSFET is higher than that of the double trench MOSFET.  The thermal and mechanical stresses inside the device during short-circuit test are simulated to explore the failure mechanism and reveal the impact of device structure on device reliability.  Finally, a post-failure analysis was performed to verify the root cause of the equipment failure.  
  • 2.2K
  • 28 Mar 2022
Topic Review
Bluetooth Low Energy Mesh Networks
Bluetooth Low Energy (BLE) is an increasingly prevalent Wireless Ad-Hoc Network (WAHN) technology for battery-powered Internet of Things (IoT) devices [1]. The BLE standard was introduced by the Bluetooth Special Interest Group (SIG) in Bluetooth version 4.0, and subsequently enhanced in versions 4.2 and 5. Initially, BLE 4.x adopted the legacy Bluetooth Personal Area Network (PAN) model for multi-hop communications and the interconnection of networks. BLE 5 intends to address these inadequacies via the implementation of pure mesh topology to provide enhanced network coverage, inter-network connectivity, and improved security [2].
  • 2.1K
  • 28 Oct 2020
Topic Review
Ultra-Low-Frequency Oscillation
One of the prominent problems faced with hydro-dominant power system is ultra-low-frequency oscillation (ULFO) with a frequency deviation of 0.1 Hz lower, which is caused by the negative damping of hydro generators. ULFO might lead to an oscillation of all generators with the same oscillation frequency, restricting consumption of hydropower renewable energy.
  • 2.1K
  • 27 Oct 2020
Topic Review
Virtual Power Plant Optimization in Smart Grids
Virtual power plants (VPPs) are promising solutions to address the decarbonization and energy efficiency goals in the smart energy grid. They assume the coordination of local energy resources such as energy generation, storage, and consumption. They are used to tackle problems brought by the stochastic nature of renewable energy, lack of energy storage devices, or insufficient local energy flexibility on the demand side. VPP modeling, management, and optimization are open to research problems that should consider, on one side, the local constraints in the operation of the energy resources and power flows and the energy grid’s sustainability objectives on the other side. There are multiple goals to create a VPP, such as to deliver energy services on a market or to the grid operator, to operate a microgrid in autonomy decoupled from the main grid, or to sustain local energy communities. 
  • 2.1K
  • 27 May 2022
Topic Review
Plug-in Electric Vehicles in Japan
The fleet of light-duty plug-in electric vehicles in Japan totaled about 303,000 highway legal plug-in electric vehicles in circulation at the end of 2019, consisting of 152,320 all-electric passenger cars, 141,680 plug-in hybrids, and 8,720 light-commercial vehicles. The rate of growth of the Japanese plug-in segment slowed from 2013, with annual sales falling behind Europe, the U.S. and China since then. The segment market share fell from 0.68% in 2014 to 0.59% in 2016. Then the market share increased to 1.2% in 2017, and fell to 1.1% in 2018, and to 0.9% in 2019. Norway surpassed Japan as the country with the third largest plug-in car stock in use in 2019. The decline in plug-in car sales reflects the Japanese government and the major domestic carmakers decision to adopt and promote hydrogen fuel cell vehicles instead of plug-in electric vehicles, although the first commercially produced hydrogen fuel cell automobiles began in 2015. (As of April 2018), the Nissan Leaf all-electric car ranked as the all-time top selling plug-in electric vehicle in the country, with over 100,000 units sold since December 2010. Ranking second is the Mitsubishi Outlander P-HEV with 34,830 units delivered through August 2016, followed by the Toyota Prius PHV with 22,100 units sold through April 2016. (As of December 2012), Japan was the country with the highest ratio of quick charging points to electric vehicles (EVSE/EV), with a ratio of 0.030 (As of December 2012). The country's charging infrastructure included 1,381 public quick-charge stations and around 300 non-domestic slow charger points. The Japanese government has set up a target to deploy 2 million slow chargers and 5,000 fast charging points by 2020.
  • 2.1K
  • 04 Oct 2022
Topic Review
Electric Vehicles in Hong Kong
The adoption of electric vehicles in Hong Kong is actively supported by the HK government, which recognizes battery electric vehicles, plug-in hybrids, and conventional hybrid electric vehicles to be environmentally friendly and eligible for financial incentives. As of 31 October 2017, there were 11,039 electric vehicles in Hong Kong, up from less than 100 in 2010. At present, 73 EV models from eight countries have been approved by the Transport Department to be eligible for the incentives. These include 51 models for private cars and motorcycles and 22 models for public transport and commercial vehicles.
  • 2.1K
  • 21 Nov 2022
Topic Review
CMOS Amplifiers
CMOS amplifiers are ubiquitous analog circuits which are used in computers, audio systems, smart phones, cameras, telecommunication systems, biomedical circuits and many other systems, and their performance has great impact on the overall specifications of the systems. They take their name from the use of MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as opposite to Bipolar Junction Transistors (BJT). MOSFETS are simpler to fabricate and therefore less expensive than BJT amplifiers, still providing a sufficiently high transconductance to allow the design of very high performance circuits. In high performance CMOS amplifier circuits, transistors are not only used to amplify the signal but are also used as active loads to achieve higher gain and output swing in comparison with resistive loads. CMOS technology had been primarily introduced to design digital circuits. In the last decades, in order to improve speed, power consumption, required area and other aspects of digital integrated circuits (ICs), the feature size of MOSFET transistors has shrunk (minimum channel length of transistors reduces in newer CMOS technologies). This phenomenon predicted by Gordon Moore in 1975, which is called Moore’s law, and states that in about each 2 years, the number of transistors doubles for the same silicon area of ICs. Progress in memory circuits design is an interesting example to see how process advancement have affected the required size and their performance in the last decades. In 1956, a 5MB Hard Disk Drive (HDD) weighted over a tone, while these days having 50000 times more capacity with a weight of several tens of grams is very common. While digital ICs have enormously benefited from the feature size shrinking, analog CMOS amplifiers have not gained corresponding advantages due to the intrinsic limitations imposed by an analog design, like the intrinsic gain reduction of short channel transistors which affects the overall gain of amplifier. Novel techniques to achieve higher gain also create new problems, like stability of amplifier for closed-loop applications. In the following, we will address both aspects and summarize few different methods to overcome these problems.
  • 2.1K
  • 07 Nov 2022
Topic Review
Electricity Demand Forecasting
With the globally increasing electricity demand, its related uncertainties are on the rise as well. Therefore, a deeper insight into load forecasting techniques for projecting future electricity demands becomes imperative for business entities and policymakers. The electricity demand is governed by a set of different variables or “electricity demand determinants”. These demand determinants depend on forecasting horizons (long term, medium term, and short term), the load aggregation level, climate, and socio-economic activities. In this paper, a review of different electricity demand forecasting methodologies is provided in the context of a group of low and middle-income countries. The article presents a comprehensive literature review by tabulating the di fferent demand determinants used in di fferent countries and forecasting the trends and techniques used in these countries. A comparative review of these forecasting methodologies over di fferent time horizons reveal that the time series modeling approach has been extensively used while forecasting for long and medium terms. For short term forecasts, artificial intelligence-based techniques remain prevalent in the literature. Furthermore, a comparative analysis of the demand determinants in these countries indicates frequent use of determinants like the population, GDP, weather, and load data over di fferent time horizons.
  • 2.1K
  • 05 Aug 2020
Topic Review
Infra-red Search and Track
An infrared search and track (IRST) system (sometimes known as infrared sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation (see Infrared signature) such as jet aircraft and helicopters. IRST is a generalized case of forward looking infrared (FLIR), i.e. from forward-looking to all-round situation awareness. Such systems are passive (thermographic camera), meaning they do not give out any radiation of their own, unlike radar. This gives them the advantage that they are difficult to detect. However, because the atmosphere attenuates infrared to some extent (although not as much as visible light) and because adverse weather can attenuate it also (again, not as badly as visible systems), the range compared to a radar is limited. Within range, angular resolution is better than radar due to the shorter wavelength.
  • 2.1K
  • 14 Oct 2022
Topic Review
Failure Modes of the Electric Motors
The reliability assessment of electric machines plays a very critical role in today’s engineering world. The reliability assessment requires a good understanding of electric motors and their root causes. Electric machines mostly fail due to mechanical problems and bearing damage is the main source of this. The bearings can be damaged by mechanical, electrical, and thermal stresses. Among all stresses, the researcher should give special attention to the electrical one, which is bearing current and shaft voltage.
  • 2.1K
  • 21 Jun 2023
Topic Review
Graphene in Strain Sensing Applications
Strain sensors, otherwise known as strain gauges, are fueled by various nanomaterials, among which graphene has attracted great interest in recent years, due to its unique electro-mechanical characteristics. Graphene shows not only exceptional physical properties but also has remarkable mechanical properties, such as piezoresistivity, which makes it a perfect candidate for strain sensing applications. 
  • 2.1K
  • 04 Feb 2022
Topic Review
Single Event Upset
A single event upset (SEU) is a change of state caused by one single ionizing particle (ions, electrons, photons...) striking a sensitive node in a micro-electronic device, such as in a microprocessor, semiconductor memory, or power transistors. The state change is a result of the free charge created by ionization in or close to an important node of a logic element (e.g. memory "bit"). The error in device output or operation caused as a result of the strike is called an SEU or a soft error. The SEU itself is not considered permanently damaging to the transistor's or circuits' functionality unlike the case of single event latchup (SEL), single event gate rupture (SEGR), or single event burnout (SEB). These are all examples of a general class of radiation effects in electronic devices called single event effects (SEE).
  • 2.1K
  • 24 Oct 2022
Topic Review
Multi-Level Inverter
Multilevel inverter had been paid a lot of attention from the academia and research community in recent times due to its role in high and medium power applications. 
  • 2.0K
  • 03 Mar 2021
Topic Review
Paper-Based Sensors Application
Paper-based sensors are getting increasing attention for reliable indoor/outdoor onsite detection with non-expert operation due to low cost, portability, easy disposal, and high accuracy, as well as bulky reduced laboratory equipment. They have become powerful analysis tools in trace detection with ultra-low detection limits and extremely high accuracy, resulting in their great popularity in biological detection, environmental inspection, and other applications. However, the current paper-based sensors still encounter insufficiencies such as harsh storage, short shelf time, singleplex analyte detection, disability of holographic strain detection, and low reproducibility for direct detection of the actual sample without pretreatment. Efforts should be made to paper-based sensors with those concerns before their broad commercial application. 
  • 2.0K
  • 22 Sep 2021
Topic Review
Issues and Challenges of Solid-State Transformer Technology
Solid-state transformer (SST) technology is one of the developing technologies that will be widely used in the future to integrate low-voltage and high-voltage networks with control circuitries and power electronics converters, facilitating renewables integration in smart grid applications. SST technology has crucial key advantageous features, including compact size and weight, low cost, and ease of connection in offshore applications. However, SST technology exhibits a few concerns, such as implementation, protection, economic, and communication compatibility, that need to be addressed.
  • 2.0K
  • 16 Sep 2022
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