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Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 620
Author(s):  
Valentina Palazzi ◽  
Luca Roselli ◽  
Manos M. Tentzeris ◽  
Paolo Mezzanotte ◽  
Federico Alimenti

This paper presents a novel passive Schottky-diode frequency doubler equipped with an on-off keying (OOK) modulation port to be used in harmonic transponders for both identification and sensing applications. The amplitude modulation of the second-harmonic output signal is achieved by driving a low-frequency MOSFET, which modifies the dc impedance termination of the doubler. Since the modulation signal is applied to the gate port of the transistor, no static current is drained. A proof-of-concept prototype was manufactured and tested, operating at 1.04 GHz. An on/off ratio of 23 dB was observed in the conversion loss of the doubler for an available input power of −10 dBm. The modulation port of the circuit was excited with a square wave (fm up to 15 MHz), and the measured sidebands in the spectrum featured a good agreement with the theory. Then, the doubler was connected to a harmonic antenna system and tested in a wireless experiment for fm up to 1 MHz, showing an excellent performance. Finally, an experiment was conducted where the output signal of the doubler was modulated by a reed switch used to measure the rotational speed of an electrical motor. This work opens the door to a new class of frequency doublers, suitable for ultra low-power harmonic transponders for identification and sensing applications.


2022 ◽  
Author(s):  
Osman Cifci ◽  
Mikayla Yoder ◽  
Lu Xu ◽  
Hao Chen ◽  
Christopher Beck ◽  
...  

Abstract A key display characteristic is its efficiency (emitted light power divided by input power). While display efficiencies are being improved through emissive (e.g., quantum dot and organic light emitting display (OLED) designs1,2, which remove the highly inefficient color filters found in traditional liquid crystal displays (LCDs)3,4, polarization filters, which block about 50% of the light, remain required to inhibit ambient light reflection. We introduce a luminescent cavity design to replace both the color and polarization filters. Narrow-band, large Stokes shift, CdSe/CdS quantum dot emitters are embedded in a reflective cavity pixel element with a small top aperture. The remainder of the top surface is coated black reducing ambient light reflection. A single pixel demonstrates an extraction efficiency of 40.9% from a cavity with an 11% aperture opening. A simple proof-of-concept multi-pixel array is demonstrated.


YMER Digital ◽  
2022 ◽  
Vol 21 (01) ◽  
pp. 206-219
Author(s):  
M Devika ◽  
◽  
L Pavithra ◽  

The wind energy is one of the low qualities because of change in direction and velocity of wind. So, the input power and the frequency will be varied which affects the operation of system. For a prescribed wind velocity, the mechanical power available from the wind turbine is function of shaft speed. The shaft speed is varying due to the change in the wind velocity; thereby change in frequency and voltage is developed at the output of the induction generator. Power electronics converters are used for stabilizing the varying parameters and to obtain a constant frequency of 50Hz. commonly used power electronic device is back-to-back converters or ACDC-AC converters which has many disadvantages like costly, bulky. Through matrix converter, the terminal voltage and frequency of the induction generator can be controlled in such a way that the wind turbine will be operating at a constant frequency of 50 Hertz.


Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 121
Author(s):  
Chao Xu ◽  
Yi Fan ◽  
Xiongying Liu

A circularly polarized implantable antenna integrated with a voltage-doubled rectifier (abbr., rectenna) is investigated for microwave wireless power transfer in the industrial, scientific, and medical (ISM) band of 2.4–2.48 GHz. The proposed antenna is miniaturized with the dimensions of 7.5 mm × 7.5 mm × 1.27 mm by etching four C-shaped open slots on the patch. A rectangular slot truncated diagonally is cut to improve the circular polarization performance of the antenna. The simulated impedance bandwidth in a three-layer phantom is 30.4% (1.9–2.58 GHz) with |S11| below −10 dB, and the 3-dB axial-ratio bandwidth is 16.9% (2.17–2.57 GHz). Furthermore, a voltage-doubled rectifier circuit that converts RF power to DC power is designed on the back of the antenna. The simulated RF-to-DC conversion efficiency can be up to 45% at the input power of 0 dBm. The proposed rectenna was fabricated and measured in fresh pork to verify the simulated results and evaluate the performance of wireless power transfer.


Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Woo-Hyeon Kim ◽  
Chang-Woo Kim ◽  
Hyo-Seob Shin ◽  
Kyung-Hun Shin ◽  
Jang-Young Choi

Linear oscillating machines are electric devices that reciprocate at a specific frequency and at a specific stroke. Because of their linear motion, they are used in special applications, such as refrigerators for home appliances and medical devices. In this paper, the structure and electromagnetic characteristics of these linear oscillating machines are investigated, and the stroke is calculated according to voltage and motion equations. In addition, static and transient behavior analysis is performed, considering mechanical systems such as springs, damping systems, and mover mass. Furthermore, in this study, the magnetic force is analyzed, experiments are conducted according to the input power, and the current magnitude and stroke characteristics are analyzed according to the input frequency. Finally, the study confirmed that the most efficient operation is possible when the electrical resonance frequency matches the resonance frequency of the linear oscillating machines.


2022 ◽  
Vol 17 ◽  
pp. 9-20
Author(s):  
Mostafa El-Sayed ◽  
Ahmed Huzayyin ◽  
Abdelmomen Mahgoub ◽  
Essam Abulzahab

The prevalence rate of photovoltaics (PV)-based generation systems has increased by more than 15 folds in the last decade, putting it on the top compared to any other power generation system from the expandability point of view. A portion of this huge expansion serves to energize standalone remote areas. Seeking improvements from different aspects of PV systems has been the focus of many studies. In the track of these improvements, parallel MPPT configuration for PV standalone systems have been introduced in the literature as an alternative to a series configuration to improve the overall efficiency of standalone PV systems. However, this efficiency improvement of the parallel MPPT configuration over the series one is not valid for any standalone application, therefore an assessment procedure is required to determine the most efficient MPPT configuration for different standalone applications. Therefore, in this study, an assessment procedure of parallel MPPT is conducted to demonstrate the suitability of utilizing such a configuration compared to series one, based on load daytime energy contributions. This assessment will help PV system designers to determine which MPPT configuration should be selected for applications under study. Furthermore, a new utilization of parallel MPPT configuration is introduced for operating universal input power supply (UIPS) loads to eliminate the inverter stage, thereby increasing the overall system efficiency and reliability. Finally, a systematic procedure to size the complete system is introduced and reinforced by a sizing example.


2022 ◽  
Author(s):  
Shuyu Dai ◽  
Defeng Kong ◽  
Vincent Chan ◽  
Liang Wang ◽  
Yuhe Feng ◽  
...  

Abstract The numerical modelling of the heat flux distribution with neon impurity seeding on CFETR has been performed by the three-dimensional (3D) edge transport code EMC3-EIRENE. The maximum heat flux on divertor targets is about 18 MW m-2 without impurity seeding under the input power of 200 MW entering into the scrape-off layer. In order to mitigate the heat loads below 10 MW m-2, neon impurity seeded at different poloidal positions has been investigated to understand the properties of impurity concentration and heat load distributions for a single toroidal injection location. The majority of the studied neon injections gives rise to a toroidally asymmetric profile of heat load deposition on the in- or out-board divertor targets. The heat loads cannot be reduced below 10 MW m-2 along the whole torus for a single toroidal injection location. In order to achieve the heat load mitigation (<10 MW m-2) along the entire torus, modelling of sole and simultaneous multi-toroidal neon injections near the in- and out-board strike points has been stimulated, which indicates that the simultaneous multi-toroidal neon injections show a better heat flux mitigation on both in- and out-board divertor targets. The maximum heat flux can be reduced below 7 MWm-2 on divertor targets for the studied scenarios of the simultaneous multi-toroidal neon injections.


Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 320
Author(s):  
Muttahid Ull Hoque ◽  
Deepak Kumar ◽  
Yves Audet ◽  
Yvon Savaria

In this article, the concept of a 22-kW microwave-powered unmanned aerial vehicle is presented, where the critical system architecture is analyzed and modeled for wirelessly transferring microwave power to the flying UAVs. The microwave system transmitting power at a 35 GHz frequency was found to be suitable for low-cost and compact architectures. The size of the transmitting and receiving systems are optimized to 108 m2 and 90 m2, respectively. A linearly polarized 4 × 2 rectangular microstrip patch antenna array has been designed and simulated to obtain a high gain, high directivity, and high efficiency in order to satisfy the power transfer requirement. The numerically simulated gain, directivity, and efficiency of the proposed patch antenna array are 13.4 dBi, 14 dBi, and 85%, respectively. Finally, a rectifying system (rectenna) is optimized using the Agilent advanced design system (ADS) software as a microwave power receiving system. The proposed rectenna has an efficiency profile of more than 80% for an RF input power range of 9 to 18 dBm. Moreover, the RF-to-DC conversion efficiency and DC output voltage of the proposed rectenna is 80% and 3.5 V, respectively, for a 10 dBm input power at 35 GHz with a load of 1500 Ω.


Author(s):  
Maha Yousif Hasan ◽  
Dheyaa Jasim Kadhim

Many consumers of electric power have excesses in their electric power consumptions that exceed the permissible limit by the electrical power distribution stations, and then we proposed a validation approach that works intelligently by applying machine learning (ML) technology to teach electrical consumers how to properly consume without wasting energy expended. The validation approach is one of a large combination of intelligent processes related to energy consumption which is called the efficient energy consumption management (EECM) approaches, and it connected with the internet of things (IoT) technology to be linked to Google Firebase Cloud where a utility center used to check whether the consumption of the efficient energy is satisfied. It divides the measured data for actual power (A_p ) of the electrical model into two portions: the training portion is selected for different maximum actual powers, and the validation portion is determined based on the minimum output power consumption and then used for comparison with the actual required input power. Simulation results show the energy expenditure problem can be solved with good accuracy in energy consumption by reducing the maximum rate (A_p ) in a given time (24) hours for a single house, as well as electricity’s bill cost, is reduced.


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