The objective of this work is to develop a mathematical model for studying the magnetic control field of a magnetically controlled ferrovariometer in a linear approximation. This problem is solved on ...the basis of a plane-parallel model. The solution is based on the method of secondary sources. On the basis of the developed mathematical model, a program is compiled in a highlevel language that provides input of initial data and their printing, calculation of the coordinates of secondary sources and calculation of the initial approximate value of the associated currents, as well as iterative calculation of the system of equations with a given accuracy. The described method and program make it possible to obtain an approximate picture of the distribution of the control field in the design of a magnetically controlled ferrovariometer and in the surrounding space, if the design can be represented by a plane-parallel model. Based on the field calculation, it is possible to perform a parametric synthesis of the control circuit design and evaluate its interfering effect on the surrounding electrical circuits.
The COVID-19 pandemic has revealed numerous global health system deficits, even in developed countries. The high cost and shortage of treatment, health care, and medical devices are the reasons. ...Aside from new mutations, the availability of respirators is an urgent concern, especially in developing countries. Even after the pandemic, respiratory diseases are among the most prevalent diseases. Researchers can help reduce treatment costs by offering scalable, open-source solutions that are manufacturable. Since March 2020, serious efforts have been made to reduce the problems caused by the lack of respirators at the lowest possible cost. In this research paper, a unique and integrated solution for a fully automatic ventilator is presented and described. The design considers the cost, speed of assembly, safety, ease of use, robustness, portability issues, and scalability to fit all requirements for emergency ventilation. Furthermore, the device was developed using turbine technology to generate air pressure. The work describes a low-cost alternative ventilator that uses a novel proportional-valve approach to control oxygen mixing process, control circuit, and control algorithm. The current software supports pressure mode controllers, and it can be upgraded to volume-mode or dual mode without any modifications in the hardware. In addition, the hardware, particularly the electronic circuit, has idle input/output ports for further development. Based on the evaluations of the developed ventilator using an artificial lung, the system exhibited acceptable accuracy regarding to the pressure, leak compensation, and oxygen concentration levels. The designated safety conditions have been met, and the safety alarms tripped according to any violations. Moreover, all design files are provided with clear instructions to rebuild the device, despite the complexity of electronics assembly. The system can be described as a development kit, which can shorten the time for researchers/manufacturers to develop a device equivalent to the expensive devices available in the market.
A fully integrated area efficient digital control circuit based on the ISO/IEC 15693 protocol is proposed for high frequency RFID tag chip. The proposed circuit is mainly composed of pulse position ...modulation decoder, Manchester encoder, anticonllision, low power circuit and other control logic. It supports six different data rates, namely, low or high data rate with one subcarrier (6.62 or 26.48 Kbit/s), low or high data rate with two subcarriers (6.67 or 26.69 Kbit/s), fast data rate with one subcarrier (13.24 or 52.97 Kbit/s). The proposed digital control circuit was integrated in an RFID tag IC and was fabricated using a 0.18-µm 2P6M CMOS process with an area of 306µm by 326µm which is smaller than the existing designs. Besides of small area, the circuit has an advantage of low power with a power consumption of less than 50µW.
We propose a low-cost programmable metasurface (PM) with distinct advantages of being 1 bit or quasi-2 bit, featuring dual polarization, and requiring fewer I/O pins. This design merges the control ...circuit and the microwave structure layout on a thin, single-layer printed circuit board (PCB). To achieve this, we transform the aperiodic control circuit into a periodic circuit by loading D flip-flops, which is further simplified by loading controlled current sources (CCSs). Based on the layout of the bias lines, a capacitive slot is added to form the microwave structure. Two PIN diodes are orthogonally surface-mounted to achieve dual-polarization characteristics. In unit arraying, D flip-flops are staggered to reduce I/O pins usage. The design can be easily extended to quasi-2 bit by stacking the PCBs. A <inline-formula> <tex-math notation="LaTeX">16\times16\,\,1 </tex-math></inline-formula>-bit PM is simulated, fabricated, and measured to verify this design. The simulation includes functions such as generating high-gain beams, multibeams, and electromagnetic (EM) waves carrying orbital angular momentum (OAM). The far-field patterns exhibited a ±60° scanning range, achieving a maximum aperture efficiency of 25%. This design introduces a simple, cost-effective, adjustable operating frequency, dual-polarization, 1-bit, or quasi-2-bit PM, with potential applications in communication, imaging, and sensing scenarios.
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•We implement a plug and play I-V curve tracer for operating PV modules.•We use a power MOSFET load, as the best recommendation of IEC60904-1 standard.•We design an RC circuit to ...generate a steady VGS amplitude controlled via the PWM.•We investigate PV module degradation from the measured I-V characteristics.•We identify fault signatures and applied them to the measured I-V characteristics.
The performance assessment of operating photovoltaic modules under real conditions is a necessity. Engineers usually use commercial I-V curve tracers available in the market. Nevertheless, most of them are expensive and limited in the input voltage. This paper outlines a low-cost equipment for tracing current-voltage characteristics of photovoltaic systems using a relay to connect the operating module under test to the varying load, which is a power MOSFET transistor. The new developments of this work include the design of an RC circuit to generate a steady gate-source voltage amplitude controlled via a PWM varying duty cycle. Also, a flexible modular voltage measurement that consists of a voltage booster to increase the input voltage capacity of the developed curve tracer is proposed. This paper investigated the impact of PV module degradations such as discoloration, cell cracks, and PID on the I-V curve in the case of crystalline technology and compared to similar modules taken as reference.
This brief proposes a design approach for a high-efficiency continuous class-F power amplifier (PA) using quasi-elliptic low-pass filtering matching network (QELMN). In comparison with Chebyshev and ...modified elliptic matching networks, QELMN is composed of the quasi-elliptic low-pass filter (QEL) and optimized transmission lines (TL). QEL is a harmonic controller and matching circuit with low insertion loss, and its passband can be adjusted for each desired amplifier according to the operating band. Sharp roll-off and wide stopband of QEL controls harmonics, and low insertion loss of QEL improves delivered power from transistor to the load. The input impedance of QELMN is optimized with the goals of the stability and high power-added efficiency. The proposed approach is adopted to implement a continuous class-F PA using an LDMOS device under a class-AB bias condition. Experimental results verify a wide bandwidth from 0.3 to 1 GHz, with measured drain efficiency of 62-81%, the output power of 37-40.3 dBm and power gain of 12-15.3 dB.
This article presents a low-loss correction technique for a self-healing load-insensitive power amplifier (PA) using a modified two-tap six-port network, wherein the varying (complex) load is first ...compensated for its unwanted susceptance part, followed by adjustment of the transistor output stage to the ohmic load variation, by modifying its supply voltage and drive level. This two-step approach avoids the high-Q conditions that occur in tunable matching network solutions, which aims to correct for both the real and imaginary load deviations, such as providing lower insertion loss and voltage stress. Next, to facilitate a fully automated load mismatch correction without the need for calibration, a modified two-tap six-port network for impedance detection and control loop approach is proposed. As proof of principle, a prototype 900-MHz class-AB PA featuring the proposed correction technique, as well as, the six-port reflectometer and the control loop, has been implemented as a PCB demonstrator. Measurement results show that the self-healing load-insensitive PA in the events of load mismatch significantly improves the performance and approaches the 50-<inline-formula> <tex-math notation="LaTeX">\Omega </tex-math></inline-formula> performance. On a 2:1 VSWR 360° mismatch trajectory and driven by a 64-QAM 3.86-MHz signal, the PA achieves a linear output power of 22 dBm with only ±0.1-dB variation and better than −45-dBc adjacent channel power ratio (ACPR).
Abstract
As the society is technologically advancing, there is an increasing demand for advancements in computers. Therefore, computers will be replacing more human jobs in the future which force ...computers to work more frequently. This foreshadows that computers may encounter more problems such as overheating problem in the future as they are operating. Overheating problem is indeed a problem to be researched because it may cause serious damages to the computer overall, such as shortening its lifespan or reducing its memory. In this article, we aim to demonstrate different existing modern solutions that may prevent Central Processing Units in computers from overheating. Furthermore, this article will be evaluating on the solutions that are presented.
In this study, a dead-time control circuit is proposed to generate independent delays for the high and low sides of half-bridge converter switches. In addition to greatly decreasing the losses of ...power converters, the proposed method mitigates the shoot-through current through the application of superimposed power switches. The circuit presented here comprises a switched capacitor architecture and is implemented in AMS 0.35 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> technology. In the implementation, the proposed dead-time control circuit occupies a silicon area of <inline-formula> <tex-math notation="LaTeX">70\,\,\mu \text{m}\,\,\times 180\,\,\mu \text{m} </tex-math></inline-formula>. To realize the technique, a two-sided wide swing current source is employed. Each sides of the current source comes with two capacitors, two Schmitt triggers, and three transmission gates. Results show that the low and high sides of the projected half-bridge converter switches respectively require delays of 35 and 62 ns. The performance of the proposed dead-time circuit is evaluated by assembling it with the half-bridge converter. The proposed dead-time prototype achieves a 40% drop in power losses in the half-bridge circuit.
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