This paper reports a reference-less frequency- detector-less single-loop bang-bang clock and data recovery (BBCDR) circuit featuring wide frequency acquisition. We use a current-starved ring ...oscillator controlled by a 5-bit resistive digital-to-analog converter to maintain quarter-rate operation, supporting a capture range of 110.4%. By the virtue of a deliberate-current-mismatch charge pump pair, we form the single-sided capture scheme in the frequency detection characteristic, eliminating the power-hungry circuits in the high-speed clock and data paths. Employing a hybrid control circuit, the proposed BBCDR automates frequency acquisition and phase tracking in the overall 32 bands. Prototyped in a 65-nm CMOS, the BBCDR covers a wide data rate from 10.8 to 37.4 Gb/s, achieving an acquisition speed of 4.63 (Gb/s)/<inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> and an energy efficiency of 1.3 pJ/bit.
In view of the limited power supply capacity of the explosion-proof computer at the borehole and the need to lift the drill to replace the battery for the rechargeable battery pack, a turbine power ...generation device for underground coal mines was developed. Based on the overall structural design of the turbine power generator, the number of turbine and guide wheel blades and the spiral angle were optimized, and a main control circuit was developed with a self-shutdown and recovery function of the battery unit. The performance test of the turbine power generator shows that the power generation capacity of the turbine power generator can reach 13 W when the flushing fluid flow rate is maintained at 390 L/min, and when the flow of electric washing liquid is kept at 200 L/min, the charging power of the turbine generator unit is stable and the charging process is reliable during the charging process of 300 min; after nearly 3 hours of temperature rise performance test, the temperature of the turbine generator was
Multi-level voltage source inverter (VSI) fed doubly fed induction machine (DFIM) has gained prominence in large rated hydro-generating unit (HU) since it provides part load operation with reduced ...power converter rating and high dynamic stability. Power converters connected in rotor side control real and reactive power of the unit. This study discusses the condenser operation of variable speed HU (250 MW), to be commissioned in Tehri plant (India), with the power flow diagram. Further, it provides dynamic behaviour and survivability status of the DFIM unit during power converter and control circuit faults where power converter redundancy is not available in large rated DFIM unit. Economic analysis of 250 MW HU under power converter and control circuit failures are also investigated. The present work also explores fault tolerant operation of a 250 MW DFIM unit at open switch fault in converters to increase the continuity of the unit operation which provides additional 2% of reactive power support to the grid compared to the DFIM without power converter redundancy operation. Open switch fault is detected through Park's vector phase currents technique and variation in DC link voltage. The computer simulation results are validated in an experiment carried on 2.2 kW DFIM in the laboratory.
Reaction Wheel for Small Satellites TAJIMA, Takao
Journal of the Japan Society for Precision Engineering,
2020/12/05, Letnik:
86, Številka:
12
Journal Article
This study presents a radiofrequency (RF)-energy-harvesting integrated circuit (IC) for powering wireless sensor networks with a wireless transmitter with an industrial, scientific, and medical (ISM) ...of 915 MHz. The proposed IC comprises an RF-direct current (DC) rectifier, an over-voltage protection circuit, a low-power low-dropout (LDO) voltage regulator, and a charger control circuit. In the RF-DC rectifier circuit, a six-stage Dickson voltage multiplier circuit is used to improve the received RF signal to a DC voltage by using native MOS with a small threshold voltage. The over-voltage protection circuit is used to prevent a high-voltage breakdown phenomenon from the RF front-end circuit, particularly for near-field communication. A low-power LDO regulator is designed to provide stable voltage by using zero frequency compensation and a voltage-trimming feedback. Charging current is amplified N times by using a current mirror to rapidly and stably charge a battery in the proposed charger control circuit. The obtained results revealed that the maximum power conversion efficiency of the proposed RF-energy-harvesting IC was 40.56% at an input power of -6 dBm, an output voltage of 1.5 V, and a load of 30 kΩ. A chip area of the RF-energy-harvesting IC was 0.58 × 0.49 mm
, including input/output pads, and power consumption was 42 μW.
We present a custom-designed integrated circuit (IC) implemented in 0.25- μ m BiCMOS technology that can automatically control the Si micro-ring modulator (MRM) temperature for optimal modulation ...characteristics. The IC monitors the optical modulation amplitude (OMA) of an Si MRM and provides the optimal heater setting for the maximum OMA. The IC consists of trans-impedance amplifier, power detector, track-and-hold circuit, comparator, digital-to-analog converter, and digital controller, all of which are integrated in a single chip. We demonstrate that, with this IC, an Si MRM can provide the maximum OMA for 25-Gb/s operation despite changes in temperature and input optical power.
Active noise control technique was used to reduce noise generated by a grass cutting machine. Grass cutting machine running on a diesel engine generates loud noise of about 105 dBA. Based on the ...spectral analysis of engine noise, it was observed that frequencies in the range of 440–5000 Hz were having more noise power. An active noise control circuit was designed and fabricated using operational amplifiers. The active noise control circuit was tested with the help of a duct made of thermocol. Results show that reduction in noise up to 10 dBA was obtained when the active noise control circuit was used with a duct made of thermocol, while a reduction up to 5 dBA was obtained when used on a grass cutting machine. The active noise control system developed may be used to reduce noise generated by a grass cutting machine.
The high prevalence of internet addiction (IA) has become a worldwide problem that profoundly affects people's mental health and executive function. Empirical studies have suggested trait anxiety ...(TA) as one of the most robust predictors of addictive behaviors. The present study investigated the neural and socio-psychological mechanisms underlying the association between TA and IA.
Firstly, we tested the correlation between TA and IA. Then we investigated the longitudinal influence of TA on IA using a linear mixed effect (LME) model. Secondly, connectome-based predictive modeling (CPM) was employed to explore neuromarkers of TA, and we tested whether the identified neuromarkers of TA can predict IA. Lastly, stressful life events and default mode network (DMN) were considered as mediating variables to explore the relationship between TA and IA.
A significant positive correlation between TA and IA was found and the high TA group demonstrated higher IA across time. CPM results revealed that the functional connectivity of cognitive control and emotion-regulation circuits and DMN were significantly correlated with TA. Furthermore, a significant association was found between the neuromarkers of TA and IA. Notably, the CPM results were all validated in an independent sample. The results of mediation demonstrated that stressful life events and correlated functional connectivity mediated the association between TA and IA.
Findings of the present study facilitate a deeper understanding of the neural and socio-psychological mechanisms linking TA and IA and provide new directions for developing neural and psychological interventions.
This brief presents a power management system (PMS) for microbial fuel cells (MFCs). The proposed PMS has been verified with off-the-shelf components and has been tested with two emulated MFCs. The ...proposed PMS is comprised of a fronted converter, a supercapacitor, a charge control circuit and a second converter. In the fronted converter, the maximum power extraction from MFCs is achieved. The supercapacitor is charged to 2.5 V by the MFC via the fronted converter and is discharged to 2 V. The charge control circuit manages the stored energy at the supercapacitor and transfer the energy to the second converter. During the transfer to the second converter, voltage is boosted at the capacitor to the requirement of the load (e.g., 3.3 V). With this set-up, this self-starting system achieves an end-to-end peak efficiency of 53.04% and can support loads as high as 108.9 mW. The proposed PMS therefore achieves self-startup operation in addition to high output voltage and a higher end-to-end efficiency compared to existing PMS systems.
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