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1
Upadhyay, J., M. J. Joshi, P. P. Deshpande, M. L. Sharma, and C. P. Navathe. "A high voltage programmable ramp generator." Review of Scientific Instruments 79, no. 5 (2008): 054701. http://dx.doi.org/10.1063/1.2912823.
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Huang, Xiao Zong, Lun Cai Liu, Wen Gang Huang, Jun Luo, and Dong Mei Zhu. "An Integrated Ramp Generator for PWM Voltage Regulators." Applied Mechanics and Materials 644-650 (September 2014): 3682–85. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.3682.
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An integrated ramp generator is presented in this paper. For traditional implementations, the amplitude clamp is realized with zener diode to limit the output voltage to ±VZ, while the zener diode is not available for standard CMOS process. The transmission gate is utilized to make the output voltage in the determined range. The reference voltage is provided by a bandgap voltage reference with temperature compensation, which guarantees the temperature stabilization of the frequency of the ramp generator. The ramp generator was fabricated in a commercial CMOS process. The frequency of 44kHz is achieved under the power supply of 3.5V, and the frequency variation of 41kH to 46kHz with the power supply of 3.3V to 5V.
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Wai, Rong Jong, and Jun Jie Liaw. "Design of Clock and Ramp Generator Circuit Framework with 0.9V Low Operational Voltage." Applied Mechanics and Materials 284-287 (January 2013): 2502–8. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.2502.
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In this study, a new clock and ramp generator circuit framework with a 0.9V low operational voltage is designed for the voltage-mode/current-mode-controlled power management integrated chip of a DC-DC converter. In conventional clock and ramp generator circuit with operational amplifiers, its operational voltage is limited to be over 1.5V because of the problem of a higher threshold voltage in the metal-oxide-semiconductor field-effect transistor (MOSFET). As a result, it can not work well for a pulse-width-modulation DC-DC converter when a below 1V low-voltage single-cell clean-energy power source is applied. This newly-design clock and ramp generator circuit framework without operational amplifiers is investigated to cope with the limitation of the threshold voltage in the MOSFET. Therefore, the corresponding chip size and power consumption can be reduced. Moreover, this circuit still has the functions of adjustable clock frequency and ramp slope. In addition, numerical simulations by the HSPICE software and experimental results by a real chip fabricated in the TSMC 1P6M 0.18µm CMOS process are given to verify the effectiveness of the proposed circuit to produce the clock and ramp waveforms.
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Timoshkin, Vadim V., and Semen S. Popov. "Study of electric drive with thyristor voltage regulator." Yugra State University Bulletin 18, no. 3 (2022): 99–106. http://dx.doi.org/10.18822/byusu20220399-106.
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In the modern world, the electric drive has tasks of different nature, depending on the application and technological process. At the moment, induction electric drives, which operate by direct start, are widely used. This method has negative factors: high starting currents at the launch; impact loads on the mechanical system. During continuous running mode of the electric motor with direct start, its resource and mechanical system is reduced. Thyristor voltage regulators is used extensively to solve this problem. Ramp generators are used for soft start, the parameters of which determine the settling time and how efficiently the peak currents and torques will be reduced.
 Object of research: induction electric drive with thyristor voltage regulator.
 Purpose of research: research of parameters of ramp generator for electric drive with thyristor voltage regulator.
 Methods of research: numerical methods for solving differential equations, functional diagrams, control system topology, electric drive theory.
 Main results of research: A generalized algorithm for the control system of thyristor voltage regulator keys is presented. An analysis was made for parameters of ramp generator in the electric drive with thyristor voltage regulator.
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Nguyen, Van, Hai Huynh, SoYoung Kim, and Hanjung Song. "Active EMI Reduction Using Chaotic Modulation in a Buck Converter with Relaxed Output LC Filter." Electronics 7, no. 10 (2018): 254. http://dx.doi.org/10.3390/electronics7100254.
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DC-DC buck converters are widely used in portable applications because of their high power efficiency. However, their inherent fast switching releases electromagnetic emissions, making them prominent sources of electromagnetic interference (EMI). This paper proposes a voltage-controlled buck converter that reduces EMI by using a chaotic pulse-width modulation (PWM) technique based on a chaotic triangular ramp generator. The chaotic triangular ramp generator is constructed from a simple on-chip chaotic circuit linked with a symmetrically triangular ramp circuit. The proposed converter can thus operate in the chaotic mode reducing the EMI without requiring any EMI filters. Additionally, using the triangular ramp signal can relax the requirement for a large LC output filter in chaotic mode. The effectiveness of the proposed scheme was experimentally verified with a chaotic triangular ramp generator embedded in a voltage-mode controller buck converter using a 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) process. The measurement results from a prototype showed that the EMI improvement from the proposed scheme is approximately 14.53 dB at the fundamental switching frequency with respect to the standard fixed-frequency PWM reference case.
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M., Zahangir, Khan Sheroz, Adam I., Abdul Kadir K., N. Nordin A., and N. Ibrahim S. "A Proposed Resistance-to-Time Converter with Switching Impulse Calibrators for Application in Resistive Bridge Sensors." Indonesian Journal of Electrical Engineering and Computer Science 11, no. 1 (2018): 47–50. https://doi.org/10.11591/ijeecs.v11.i1.pp47-50.
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This paper presents a simple resistance-to-time converter. It consists of two voltage comparators, a ramp voltage generator, two logic gates and impulse voltage calibrators. A square-wave generator circuit is suggested in this paper. The design is simple and independent of the OPAMP offset issues. The resulting square-wave is rectified to get its DC equivalent and to a triangular output; the two outputs are applied to a comparator for generating a digital output with a duty cycle proportional to a change in resistance upon which is dependent the DC.
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Padash, Mohsen, and Mostafa Yargholi. "Positive and Negative Feedback for Linearity Improvement and PVT Compensation of the Ramp Generator." Journal of Circuits, Systems and Computers 28, no. 02 (2018): 1950028. http://dx.doi.org/10.1142/s0218126619500282.
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Linearity of ramp signals is one of the most important aspects for many applications such as single-slope analog to digital converters (ADCs); another important aspect is the total power dissipation. Applications like high-resolution single-slope ADCs that can be used in portable devices demanded accurate ramp generator with low power dissipation. This paper presents a low power ramp generator with linearity improvement that achieved by a positive feedback circuit and negative feedback for compensation of the variations in process, voltage and temperature. Derived equations of the proposed ramp generator circuit show that linearity of the output ramp, with proper choosing of device sizes, can be enhanced significantly. Also, for proving of linearity enhancement, the circuit design and post-layout simulations were done in TSMC 0.18[Formula: see text][Formula: see text]m and 90[Formula: see text]nm CMOS technologies. Simulation results show that linearity of the circuit improved by a factor of 8 and total ramp resolution improved about 3 bit, whereas power dissipation of the circuit is about 8[Formula: see text][Formula: see text]W and entire layout core area is near 800[Formula: see text][Formula: see text]m2.
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Song, Sungyoon, Minhan Yoon, and Gilsoo Jang. "Analysis of Six Active Power Control Strategies of Interconnected Grids with VSC-HVDC." Applied Sciences 9, no. 1 (2019): 183. http://dx.doi.org/10.3390/app9010183.
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In this paper, the generator angle stability of several active power control schemes of a voltage-source converter (VSC)-based high-voltage DC (HVDC) is evaluated for two interconnected AC systems. Excluding frequency control, there has been no detailed analysis of interconnected grids depending upon the converter power control, so six different types of active power control of the VSC-HVDC are defined and analyzed in this paper. For each TSO (transmission system operator), the applicable schemes of two kinds of step control and four kinds of ramp-rate control with a droop characteristic are included in this research. Furthermore, in order to effectively evaluate the angle stability, the Generators-VSC Interaction Factor (GVIF) index is newly implemented to distinguish the participating generators (PGs) group which reacts to the converter power change. As a result, the transient stabilities of the two power systems are evaluated and the suitable active power control strategies are determined for two TSOs. Simulation studies are performed using the PSS®E program to analyze the power system transient stability and various active power control schemes of the VSC-HVDC. The results provide useful information indicating that the ramp-rate control shows a more stable characteristic than the step-control for interconnected grids; thus, a converter having a certain ramp-rate slope similar to that of the other generator shows more stable results in several cases.
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Zahangir, M., Sheroz Khan, I. Adam, K. Abdul Kadir, A. N. Nordin, and S. N. Ibrahim. "A Proposed Resistance-to-Time Converter with Switching Impulse Calibrators for Application in Resistive Bridge Sensors." Indonesian Journal of Electrical Engineering and Computer Science 11, no. 1 (2018): 47. http://dx.doi.org/10.11591/ijeecs.v11.i1.pp47-50.
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This paper presents a simple resistance-to-time converter. It consists of two voltage comparators, a ramp voltage generator, two logic gates and impulse voltage calibrators. A square-wave generator circuit is suggested in this paper. The design is simple and independent of the OPAMP offset issues. The resulting square-wave is rectified to get its DC equivalent and to a triangular output; the two outputs are applied to a comparator for generating a digital output with a duty cycle proportional to a change in resistance upon which is dependent the DC.
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Anwar, Zainuri. "SPEED BREAKER SEBAGAI PENGGERAK GENERATOR LISTRIK." Journal of Renewable Energy & Mechanics (REM) 3, no. 01 (2020): 1–5. http://dx.doi.org/10.25299/rem.2020.vol3.no01.3912.
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ABSTRACT
 The kinetic energy was produced by a moving vehicle can be used to generate power by using a speed breaker. The kinetic energy is converted into mechanical energy by altering a reciprocating connecting rod into rotation of flywheel, then it is transmitted to the generator in order to produce electrical energy. The purpose of this study was to determine the electrical energy generated from the crankshaft type speed breaker. Speed breaker used has 3 ramps with a maximum ramp height of 10 cm. the load and speed of vehicles passing the ramp are varied 72 kg, 82.5 kg, 88.7 kg at speeds of 5 km/h, 10 km/h, 15 km/h. The result of the study shows that a vehicle with the mass of 88,7 kg was able to generate a 19 V of electric voltage, 32 A of electric current and 486,4 Watts. That power is stored in a 12 V and 3 Ah batteries that needed 0.094 hour for charging. 
 Keywords: Flywheel, Generator, Kinetic energy, Speed breaker
 
 ABSTRAK
 Energi kinetik yang dihasilkan oleh kendaraan yang bergerak dapat digunakan untuk menghasilkan daya dengan menggunakan speed breaker. Energi kinetik diubah menjadi energi mekanik dengan mengubah batang penghubung bolak-balik menjadi rotasi roda gila, kemudian ditransmisikan ke generator untuk menghasilkan energi listrik. Tujuan dari penelitian ini adalah untuk mengetahui energi listrik yang dihasilkan dari speed breaker tipe poros engkol. speed breaker yang digunakan memiliki 3 ramp dengan tinggi maksimum ramp 10 cm. beban dan kecepatan kendaraan yang melewati ramp di variasikan masing - masing 72 kg, 82,5 kg, 88,7 kg dengan kecepatan 5 km/h, 10 km/h, 15km/h. Hasil penelitian menunjukkan bahwa kendaraan dengan massa 88,7 kg mampu menghasilkan tegangan listrik 19 V, arus listrik 32 A, dan 486,4 Watt. Daya itu disimpan dalam baterai 12 V dan 3 Ah yang membutuhkan 0,094 jam untuk diisi daya.
 Kata kunci: Energi kinetik, Generator, Roda gila, Speed breaker
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Anwar, Zainuri, and Eddy Elfiano. "SPEED BREAKER SEBAGAI PENGGERAK GENERATOR LISTRIK." Journal of Renewable Energy and Mechanics 3, no. 01 (2020): 1–5. https://doi.org/10.25299/rem.2020.3912.
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ABSTRACT The kinetic energy was produced by a moving vehicle can be used to generate power by using a speed breaker. The kinetic energy is converted into mechanical energy by altering a reciprocating connecting rod into rotation of flywheel, then it is transmitted to the generator in order to produce electrical energy. The purpose of this study was to determine the electrical energy generated from the crankshaft type speed breaker. Speed breaker used has 3 ramps with a maximum ramp height of 10 cm. the load and speed of vehicles passing the ramp are varied 72 kg, 82.5 kg, 88.7 kg at speeds of 5 km/h, 10 km/h, 15 km/h. The result of the study shows that a vehicle with the mass of 88,7 kg was able to generate a 19 V of electric voltage, 32 A of electric current and 486,4 Watts. That power is stored in a 12 V and 3 Ah batteries that needed 0.094 hour for charging. Keywords: Flywheel, Generator, Kinetic energy, Speed breaker ABSTRAK Energi kinetik yang dihasilkan oleh kendaraan yang bergerak dapat digunakan untuk menghasilkan daya dengan menggunakan speed breaker. Energi kinetik diubah menjadi energi mekanik dengan mengubah batang penghubung bolak-balik menjadi rotasi roda gila, kemudian ditransmisikan ke generator untuk menghasilkan energi listrik. Tujuan dari penelitian ini adalah untuk mengetahui energi listrik yang dihasilkan dari speed breaker tipe poros engkol. speed breaker yang digunakan memiliki 3 ramp dengan tinggi maksimum ramp 10 cm. beban dan kecepatan kendaraan yang melewati ramp di variasikan masing - masing 72 kg, 82,5 kg, 88,7 kg dengan kecepatan 5 km/h, 10 km/h, 15km/h. Hasil penelitian menunjukkan bahwa kendaraan dengan massa 88,7 kg mampu menghasilkan tegangan listrik 19 V, arus listrik 32 A, dan 486,4 Watt. Daya itu disimpan dalam baterai 12 V dan 3 Ah yang membutuhkan 0,094 jam untuk diisi daya. Kata kunci: Energi kinetik, Generator, Roda gila, Speed breaker
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Cheng, Jun, Qian Liu, Yu Ting Xie, et al. "Impact of Wind Farms on the Voltage of the Grid Integrated under the Ramp Changing Wind Speed." Advanced Materials Research 860-863 (December 2013): 419–23. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.419.
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The wind speed simulation model was given in this paper, combined with the power system analysis software (PSD-BPA) transient calculation of wind generator models, it implemented the wind speed disturbance of wind farms and the entire network voltage analysis. Combining the practical power grid in china, research on the power grid voltage fluctuation of the level after the large-scale wind farms integrated the system, and relevant the conclusions: In the process of wind disturbance, there is no angle stability of synchronous generator in the system, doubly-fed induction generator could emit and absorb reactive power, and thus could be able to maintain voltage stability.
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Jia, J. B., and K. N. Leung. "Integrated ramp generator with auto-set hysteretic comparator for PWM voltage regulators." Electronics Letters 43, no. 24 (2007): 1384. http://dx.doi.org/10.1049/el:20072583.
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Kim, Young-Kyu, Chung-Hee Jang, Dong-Hyun Shin, and Kwang-Hyun Baek. "A Comparator-Less Buck Converter with Fast Transient Response Using a Reactive Ramp Generator." Energies 18, no. 2 (2025): 307. https://doi.org/10.3390/en18020307.
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This paper introduces a voltage-mode DC-DC buck converter designed to address the challenges of high-frequency operation. The proposed comparator-less Reactive Ramp Generator (RRG) topology mitigates the issues associated with comparator delays, achieving a fast load transient response. By eliminating all comparators from the buck converter’s control circuit, we prevent potential delay-induced malfunctions, thereby enhancing overall operational reliability. The rapid response of the RRG, enabled by a short feedback loop, allows for swift output voltage regulation during load transients. Replacing comparators in the PWM controller with inverters effectively removes delay issues without adding complexity. Since the proposed design retains the conventional voltage-mode transfer function, standard type-3 compensation is readily applicable. Operating with a 3.3 V input, the buck converter provides an output range from 0.65 V to 3.0 V, achieving a settling time of 0.802 µs for load changes from 200 mA to 1 A, and 1.27 µs for load changes from 1 A to 200 mA. The proposed architecture achieves a peak efficiency of 92.78% at 2.4 V and 600 mA.
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Upadhyay, J., M. J. Joshi, P. P. Deshpande, M. L. Sharma, and C. P. Navathe. "Erratum: “A high voltage programmable ramp generator” [Rev. Sci. Instrum. 79, 054701 (2008)]." Review of Scientific Instruments 79, no. 8 (2008): 089901. http://dx.doi.org/10.1063/1.2976153.
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George, Gibin Chacko, N. Bittu, J. J. U. Buch, A. Amalin Prince, Neena Goveas, and Surya K. Pathak. "Characteristics of Arbitrary Ramp Generator: A Tuning Voltage Setup for the FMCW Reflectometer." IEEE Transactions on Instrumentation and Measurement 69, no. 6 (2020): 3481–92. http://dx.doi.org/10.1109/tim.2019.2939933.
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Getting, P. A., and M. S. Dekin. "Mechanisms of pattern generation underlying swimming in Tritonia. IV. Gating of central pattern generator." Journal of Neurophysiology 53, no. 2 (1985): 466–80. http://dx.doi.org/10.1152/jn.1985.53.2.466.
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Swimming behavior in the marine mollusc Tritonia diomedea is episodic, consisting of a series of alternating dorsal and ventral flexions initiated by a brief sensory stimulus. The swim motor pattern is generated by a network formed of four groups of premotor interneurons: cerebral cell 2 (C2), dorsal swim interneurons (DSIs), and two types of ventral swim interneurons (VSI-A and VSI-B). The initiation and maintenance of swimming depends on the establishment of a long-lasting ramp depolarization in both the premotor, pattern-generating interneurons, and the motor neurons (i.e., flexion neurons). Voltage clamp was used to measure the membrane current responsible for the ramp depolarization. In all cell classes the current had two components: a tonic inward current, which decayed as the swim progressed, and phasic inward current waves, which provided the synaptic drive during each swim burst. The ramp current in the flexion neurons and in C2 was generated largely by activity within the interneuronal pattern-generating network (PGN). The ramp current could be mimicked by driving activity in the pattern-generating interneurons. In VSI-B, the tonic component of the ramp current was independent of activity within the PGN and appeared to be derived from the long-lasting effect of an extrinsic input. The phasic components of the ramp, however, were dependent on PGN activity. The phasic inward current waves were blocked when pattern generation was prevented. In addition, phasic inward currents similar to those occurring during swimming could be produced by driving the C2. The tonic component of the ramp current in a DSI was dependent both on extrinsic inputs and PGN activity. Extrinsic inputs appeared to control the first 10-15 s of the tonic current. At longer times, activity within the DSI population itself maintained the ramp current. When one DSI was driven in a quiescent preparation, all other DSIs were inhibited, yet the DSIs are known to be coupled by monosynaptic, reciprocal excitatory synapses. This effect could be explained by the action of an unidentified inhibitory interneuron (I-neuron), which was excited by DSIs and in turn inhibited all other DSIs. The DSIs were therefore coupled reciprocally by both monosynaptic excitation and polysynaptic inhibition. Activity in C2 switched the DSI-DSI interaction from inhibition to excitation by inhibiting the I-neuron.(ABSTRACT TRUNCATED AT 400 WORDS)
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Chu, Hyunho, Jungmoon Kim, and Chulwoo Kim. "A monolithic voltage-mode DC-DC converter with a novel oscillator and ramp generator." IEICE Electronics Express 5, no. 17 (2008): 683–88. http://dx.doi.org/10.1587/elex.5.683.
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Fuqua, W. L., and K. B. MacAdam. "Linear high‐voltage ramp generator for use in selective field ionization of Rydberg atoms." Review of Scientific Instruments 56, no. 3 (1985): 385–88. http://dx.doi.org/10.1063/1.1138309.
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Willenberg, G. D., and H. N. Tauscher. "Novel Digital Voltage Ramp Generator for Use in Precision Current Sources in the Picoampere Range." IEEE Transactions on Instrumentation and Measurement 58, no. 4 (2009): 756–60. http://dx.doi.org/10.1109/tim.2008.2010675.
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Mc Gee, Kevin, Prince Anandarajah, and David Collins. "Current Progress towards the Integration of Thermocouple and Chipless RFID Technologies and the Sensing of a Dynamic Stimulus." Micromachines 11, no. 11 (2020): 1019. http://dx.doi.org/10.3390/mi11111019.
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To date, no printable chipless Radio Frequency Identification (RFID) sensor-related publications in the current literature discuss the possibility of thermocouple integration, particularly for the use in extreme environments. Furthermore, the effects of a time-dependent stimulus on the scattering parameters of a chipless RFID have never been discussed in the known literature. This work includes a review of possible methods to achieve this goal and the design and characterization of a Barium Strontium Titanate (BST) based VHF/UHF voltage sensing circuit. Proof-of-concept thermocouple integration was attempted, and subsequent testing was performed using a signal generator. These subsequent tests involved applying ramp and sinusoid voltage waveforms to the circuit and the characteristics of these signals are largely extracted from the scattering response. Overall conclusions of this paper are that thermocouple integration into chipless RFID technology is still a significant challenge and further work is needed to identify methods of thermocouple integration. With that being said, the developed circuit shows promise as being capable of being configured into a conventional chipless RFID DC voltage sensor.
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Kim, Hyun-Tae, Jungju Lee, Myungseok Yoon, Moon-Jeong Lee, Namhun Cho, and Sungyun Choi. "Continuation Power Flow Based Distributed Energy Resource Hosting Capacity Estimation Considering Renewable Energy Uncertainty and Stability in Distribution Systems." Energies 13, no. 17 (2020): 4367. http://dx.doi.org/10.3390/en13174367.
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Recently, the demand for electricity has been increasing worldwide. Thus, more attention has been paid to renewable energy. There are acceptable limits during the integration of renewable energy into distribution systems because there are many effects of integrating renewable energy. Unlike previous studies that have estimated the distributed energy resource (DER) hosting capacity using the standard high voltage and probability approach, in this study, we propose an algorithm to estimate the DER hosting capacity by considering DER outages due to abrupt disturbances or uncertainties based on the generator ramp rate and voltage stability, which involves analysis of the low-voltage aspects. Furthermore, this method does not involve a complicated process or need large amounts of data to estimate the DER hosting capacity because it requires only minimum data for power flow. The proposed algorithm was applied to the IEEE-33 radial distribution system. According to the DER capacity, a voltage stability analysis based on continuation power flow (CPF) was conducted in a case of DER outage to estimate the DER hosting capacity in this case study. Thus, the DER hosting capacity was estimated for the IEEE-33 radial distribution system.
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Shirazi, Najmeh Cheraghi, Abumoslem Jannesari, and Pooya Torkzadeh. "Fast-Transient-Response Low-Voltage Integrated, Interleaved DC–DC Converter for Implantable Devices." Journal of Circuits, Systems and Computers 29, no. 01 (2019): 2050013. http://dx.doi.org/10.1142/s0218126620500139.
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A new self-start-up switched-capacitor charge pump is proposed for low-power, low-voltage and battery-less implantable applications. To minimize output voltage ripple and improve transient response, interleaving regulation technique is applied to a multi-stage Cross-Coupled Charge Pump (CCCP) circuit. It splits the power flow in a time-sequenced manner. Three cases of study are designed and investigated with body-biasing technique by auxiliary transistors: Four-stage Two-Branch CCCP (TBCCCP), the two-cell four-stage Interleaved Two-Branch CCCP (ITBCCCP2) and four-cell four-stage Interleaved Two-Branch CCCP (ITBCCCP4). Multi-phase nonoverlap clock generator circuit with body-biasing technique is also proposed which can operate at voltages as low as CCCP circuits. The proposed circuits are designed with input voltage as low as 300 to 400[Formula: see text]mV and 20[Formula: see text]MHz clock frequency for 1[Formula: see text]pF load capacitance. Among the three designs, ITBCCCP4 has the lowest ramp-up time (41.6% faster), output voltage ripple (29% less) and power consumption (19% less). The Figure-Of-Merit (FOM) of ITBCCCP4 is the highest value among two others. For 400[Formula: see text]mV input voltage, ITBCCCP4 has a 98.3% pumping efficiency within 11.6[Formula: see text][Formula: see text]s, while having a maximum voltage ripple of 0.1% and a power consumption as low as 2.7[Formula: see text]nW. The FOM is 0.66 for this circuit. The designed circuits are implemented in 180-nm standard CMOS technology with an effective chip area of [Formula: see text][Formula: see text][Formula: see text]m for TBCCCP, [Formula: see text][Formula: see text][Formula: see text]m for ITBCCCP2 and [Formula: see text][Formula: see text][Formula: see text]m for ITBCCCP4.
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Akeyo, Oluwaseun M., Aron Patrick, and Dan M. Ionel. "Study of Renewable Energy Penetration on a Benchmark Generation and Transmission System." Energies 14, no. 1 (2020): 169. http://dx.doi.org/10.3390/en14010169.
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Significant changes in conventional generator operation and transmission system planning will be required to accommodate increasing solar photovoltaic (PV) penetration. There is a limit to the maximum amount of solar that can be connected in a service area without the need for significant upgrades to the existing generation and transmission infrastructure. This study proposes a framework for analyzing the impact of increasing solar penetration on generation and transmission networks while considering the responses of conventional generators to changes in solar PV output power. Contrary to traditional approaches in which it is assumed that generation can always match demand, this framework employs a detailed minute-to-minute (M-M) dispatch model capable of capturing the impact of renewable intermittency and estimating the over- and under-generation dispatch scenarios due to solar volatility and surplus generation. The impact of high solar PV penetration was evaluated on a modified benchmark model, which includes generators with defined characteristics including unit ramp rates, heat rates, operation cost curves, and minimum and maximum generation limits. The PV hosting capacity, defined as the maximum solar PV penetration the system can support without substantial generation imbalances, transmission bus voltage, or thermal violation was estimated for the example transmission circuit considered. The results of the study indicate that increasing solar penetration may lead to a substantial increase in generation imbalances and the maximum solar PV system that can be connected to a transmission circuit varies based on the point of interconnection, load, and the connected generator specifications and responses.
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Georgiou, Constantinos A., and Michael A. Koupparis. "Construction and evaluation of an automated flow injection-stopped flow analyser for multipoint reaction rate spectrophotometric methods. Determination of ammonia nitrogen, creatinine and phosphate." Journal of Automatic Chemistry 13, no. 5 (1991): 199–207. http://dx.doi.org/10.1155/s1463924691000342.
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The construction and evaluation of a fully automated Flow Injection-Stopped Flow (FI-SF) spectrophotometric analyser is described. A microcomputer (Rockwell AIM 65) is used to control the analyser (sample injection, stop and start of the pump) through a suitable interface. Data acquisition is achieved using a 12 bit ADC card and a suitable subroutine in 6502 assembly language, allowing data sampling at a frequency of 7.5 kHz. The measurement interface and software were evaluated using a voltage ramp generator. A precision of 0.02-1.1% RSD (N =10) was obtained for voltage ramps in the range of 1-37 mVs-1. The FI-SF analyser was evaluated in routine analysis by developing FI-SF kinetic spectrophotometric methods for the determination of ammonia nitrogen (20-250 ppm, 0.4-2.5% RSD) based on the Berthelot reaction, creatinine (20-220 ppm, 0.9-3.6% RSD) based on the Jaffé reaction, and phosphate (5-30 ppm, 1.0-3.3% RSD) based on the phosphomolybdenum blue reaction. The reaction rate is measured by linear fitting of multiple absorbance readings vs time. Algorithms for automated estimation of the residence time, the linear range of the reaction curve, and data treatment are presented.
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Susanta, Kumar Gachhayat, and Kumar Dash Saroj. "Modified sub-gradient based combined objective technique and evolutionary programming approach for economic dispatch involving valve-point loading, enhanced prohibited zones and ramp rate constraints." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 5 (2020): 5048–57. https://doi.org/10.11591/ijece.v10i5.pp5048-5057.
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A security constrained non-convex power dispatch problem with prohibited operation zones and ramp rates is formulated and solved using an iterative solution method based on the feasible modified sub-gradient algorithm (FMSG). Since the cost function, all equality and inequality constraints in the nonlinear optimization model are written in terms of the bus voltage magnitudes, phase angles, off-nominal tap settings, and the Susceptance values of static VAR (SVAR) systems, they can be taken as independent variables. The actual power system loss is included in the current approach and the load flow equations are inserted into the model as the equality constraints. The proposed modified sub gradient based combined objective technique and evolutionary programming approach (MSGBCAEP) with 𝜆 as decision variable and cost function as fitness function is tested on the IEEE 30-bus 6 generator test case system. The absence of crossover operation and adoption of fast judicious modifications in initialization of parent population, offspring generation and normal distribution curve selection in EP enables the proposed MSGBCAEP approach to ascertain global optimal solution for cost of generation and emission level.
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Park, Himchan, Changzhi Yu, Hyunmook Kim, Youngtaek Roh, and Jinwook Burm. "Low Power CMOS Image Sensors Using Two Step Single Slope ADC With Bandwidth-Limited Comparators & Voltage Range Extended Ramp Generator for Battery-Limited Application." IEEE Sensors Journal 20, no. 6 (2020): 2831–38. http://dx.doi.org/10.1109/jsen.2019.2957043.
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Gachhayat, Susanta Kumar, and Saroja Kumar Dash. "Modified sub-gradient based combined objective technique and evolutionary programming approach for economic dispatch involving valve-point loading, enhanced prohibited zones and ramp rate constraints." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 5 (2020): 5048. http://dx.doi.org/10.11591/ijece.v10i5.pp5048-5057.
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A security constrained non-convex power dispatch problem with prohibited operation zones and ramp rates is formulated and solved using an iterative solution method based on the feasible modified sub-gradient algorithm (FMSG). Since the cost function, all equality and inequality constraints in the nonlinear optimization model are written in terms of the bus voltage magnitudes, phase angles, off-nominal tap settings, and the Susceptance values of static VAR (SVAR) systems, they can be taken as independent variables. The actual power system loss is included in the current approach and the load flow equations are inserted into the model as the equality constraints. The proposed modified sub gradient based combined objective technique and evolutionary programming approach (MSGBCAEP) with as decision variable and cost function as fitness function is tested on the IEEE 30-bus 6 generator test case system. The absence of crossover operation and adoption of fast judicious modifications in initialization of parent population, offspring generation and normal distribution curve selection in EP enables the proposed MSGBCAEP approach to ascertain global optimal solution for cost of generation and emission level shown in Table 6 and displayed in Figure 2 and Figure 3 respectively.
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Takamatsu, Takahiro, Takashi Oozeki, Dai Orihara, et al. "Simulation Analysis of Issues with Grid Disturbance for a Photovoltaic Powered Virtual Synchronous Machine." Energies 15, no. 16 (2022): 5921. http://dx.doi.org/10.3390/en15165921.
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The increase in inverter-based resources associated with the increased installation of PV sources is a concern because it reduces the inertia of the power system during peak PV generation periods. As a countermeasure to reduce grid inertia, the addition of pseudo-inertia using virtual synchronous machines can be selected, and PV generation can cooperatively contribute to the stable operation of the power system by using the suppressed output as reserve power. However, few studies have analyzed VSMs that do not use batteries and use PV as a resource (PV-VSM) in simulations, including grid interconnection and solar radiation fluctuations, and it is necessary to clarify the issues and discuss countermeasures. In this study, electromagnetic transient response analysis was applied to a VSM connected to a two-generator system, simulations were performed, and the following findings were reported and countermeasure methods for the problem were proposed. When the PV capacity is insufficient for the output required by the VSM inverter, the PV-VSM control system may become unstable. This is caused by a drop in the capacitor voltage of the DC/DC converter due to insufficient PV output. The limiter control system is designed to address this problem by combining the headroom estimation system with the current limiting algorithm. The proposed limiter control system is validated on solar radiation ramp fluctuations as a test case and found that the system was effective in supressing PV-VSM instability. In our simulation case, the PV-VSM with our limiter control can continue to operate stably even if the PV available power is 0.03 [p.u.] short of the inverter’s reference power by the solar power ramp fluctuation, as long as the inverter installation rate is less than 50%.
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Dubin, A. E., and V. E. Dionne. "Action potentials and chemosensitive conductances in the dendrites of olfactory neurons suggest new features for odor transduction." Journal of General Physiology 103, no. 2 (1994): 181–201. http://dx.doi.org/10.1085/jgp.103.2.181.
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Odors affect the excitability of an olfactory neuron by altering membrane conductances at the ciliated end of a single, long dendrite. One mechanism to increase the sensitivity of olfactory neurons to odorants would be for their dendrites to support action potentials. We show for the first time that isolated olfactory dendrites from the mudpuppy Necturus maculosus contain a high density of voltage-activated Na+ channels and produce Na-dependent action potentials in response to depolarizing current pulses. Furthermore, all required steps in the transduction process beginning with odor detection and culminating with action potential initiation occur in the ciliated dendrite. We have previously shown that odors can modulate Cl- and K+ conductances in intact olfactory neurons, producing both excitation and inhibition. Here we show that both conductances are also present in the isolated, ciliated dendrite near the site of odor binding, that they are modulated by odors, and that they affect neuronal excitability. Voltage-activated Cl- currents blocked by 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid and niflumic acid were found at greater than five times higher average density in the ciliated dendrite than in the soma, whereas voltage-activated K+ currents inhibited by intracellular Cs+ were distributed on average more uniformly throughout the cell. When ciliated, chemosensitive dendrites were stimulated with the odorant taurine, the responses were similar to those seen in intact cells: Cl- currents were increased in some dendrites, whereas in others Cl- or K+ currents were decreased, and responses washed out during whole-cell recording. The Cl- equilibrium potential for intact neurons bathed in physiological saline was found to be -45 mV using an on-cell voltage-ramp protocol and delayed application of channel blockers. We postulate that transduction of some odors is caused by second messenger-mediated modulation of the resting membrane conductance (as opposed to a specialized generator conductance) in the cilia or apical region of the dendrite, and show how this could alter the firing frequency of olfactory neurons.
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Tobin, Anne-Elise, and Ronald L. Calabrese. "Myomodulin Increases Ih and Inhibits the Na/K Pump to Modulate Bursting in Leech Heart Interneurons." Journal of Neurophysiology 94, no. 6 (2005): 3938–50. http://dx.doi.org/10.1152/jn.00340.2005.
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In the medicinal leech, a rhythmically active 14-interneuron network composes the central pattern generator for heartbeat. In two segmental ganglia, bilateral pairs of reciprocally inhibitory heart interneurons (oscillator interneurons) produce a rhythm of alternating bursts of action potentials that paces activity in the pattern-generating network. The neuropeptide myomodulin decreases the period of this bursting and increases the intraburst spike frequency when applied to isolated ganglia containing these oscillator interneurons. Myomodulin also decreases period, increases spike frequency, and increases the robustness of endogenous bursting in synaptically isolated (with bicuculline) oscillator interneurons. In voltage-clamp experiments using hyperpolarizing ramps, we identify an increase in membrane conductance elicited by myomodulin with the properties of a hyperpolarization-activated current. Voltage steps confirm that myomodulin indeed increases the maximum conductance of the hyperpolarization-activated current Ih. In similar experiments using Cs+ to block Ih, we demonstrate that myomodulin also causes a steady offset in the ramp current that is not associated with an increase in conductance. This current offset is blocked by ouabain, indicating that myomodulin inhibits the Na/K pump. In current-clamp experiments, when Ih is blocked with Cs+, myomodulin decreases period and increases spike frequency of alternating bursting in synaptically connected oscillator interneurons, suggesting that inhibiting the Na/K pump modulates these burst characteristics. These observations indicate that myomodulin decreases period and increases spike frequency of endogenous bursting in synaptically isolated oscillator heart interneurons and alternating bursting of reciprocally inhibitory pairs of interneurons, at least in part, by increasing Ih and by decreasing the Na/K pump.
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Kunac, Antonijo, Goran Petrović, Marin Despalatović, and Marko Jurčević. "A Low-Cost Test Platform for Performance Analysis of Phasor Measurement Units." Electronics 13, no. 2 (2024): 245. http://dx.doi.org/10.3390/electronics13020245.
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In this paper, a customizable low-cost voltage waveform generator based on a real-time desktop PC and embedded data acquisition card synchronized with Coordinated Universal Time (UTC) is presented. A software approach to phase-locked loop synchronization with an external Global Positioning System (GPS) pulse signal is utilized to achieve a time uncertainty of ±1μs. This avoids expensive hardware modules for synchronization and timing purposes, which are commonly presented in literature. Besides the application for controlling the test platform, our own phasor data concentrator (PDC) application is running concurrently on the host PC. The latter is used for collecting and comparing the syncrophasor data from the test platform against the syncrophasor data measured by phasor measurement units (PMUs) under the test. The paper describes all procedures for generating reference test signals. Numerous case studies were performed, and experimental results for steady-state compliance as well as frequency ramp and phase modulation tests for dynamic compliance are presented in detail. All tests confirm that customizable test platform meets the requirements of IEEE/IEC standards. Compared to other calibrators, the cost as well as the specifications and point-by-point concept of data processing makes the described test platform suitable for performance analysis of PMU algorithms implemented on various development boards.
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Morel, Cristina, and Jean-Yves Morel. "Chaos Anticontrol and Switching Frequency Impact on MOSFET Junction Temperature and Lifetime." Actuators 14, no. 5 (2025): 203. https://doi.org/10.3390/act14050203.
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Generating chaos from originally non-chaotic systems is a promising issue. Indeed, chaos has been successfully applied in many fields to improve system performance. In this work, a Buck converter is chaotified using a combination of the switching piecewise-constant characteristic and of anticontrol of chaos feedback. For electromagnetic compatibility compliance reasons, this feedback control method is able, at the same time, to achieve low spectral emissions and to maintain a small ripple of the output voltage and the inductance current. This new feedback implies a fast and non-linear switching action of the Buck MOSFET on a period of the ramp generator. Thus, it is essential to analyze its thermal performance. This is why we propose an original analysis of the influence of anticontrol of chaos and switching frequency variation on junction temperature: we investigate the correlation between the lifetime of the power electronic switching component and its thermal stress due to the addition of chaos. It appeared that a reduction in the current ripple did not degrade the MOSFET junction thermal performance, despite the fast switching of the MOSFET. Furthermore, a small degradation in the MOSFET lifetime was indicated for chaotic behavior versus periodic behavior. Thus, this leads to the conclusion that using anticontrol of chaos produces a low accumulated fatigue effect on a Buck converter semiconductor.
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Brewer, Roger. "High Reliability Electronics for Demanding Aircraft Applications – An Overview." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2016, HiTEC (2016): 000011–17. http://dx.doi.org/10.4071/2016-hitec-11.
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Abstract The primary form of generated power on any typical aircraft (Tactical, Airlift, Commercial) requires conversion in multiple different forms (voltage levels, aircraft compliant frequency) and at various power levels to meet the total needs of the vehicle. DC:AC Power Conversion (Inverters), AC-DC Generator (conditioning) electronics, AC-AC frequency conditioning and DC:DC Power Conversion are all forms of conversion within the power system (primary, secondary tiers) typical of any aircraft. Additionally, within the power distribution network often solid state power switches in later generation aircraft and fighters are used to control and manage power (control power ramp-up for example) to loads and isolate electrical faults. The conditioning, conversion and control of this power with high reliability devices can often occur in more extreme environments (high temperatures, high vibration and confined spaces) and can present challenging issues for aerospace and specifically aircraft. Weight objectives can further add to the challenges. This paper will discuss, at largely a level based on acquired and compiled lessons learned, some of the aforementioned challenges including the susceptibility to both electrically and mechanically induced failure modes in power devices encountered in aircraft. The paper will also discuss the notion that while Wide Band Gap (WBG) technology may be the right answer in some/many applications, it may not be the answer in achieving high reliability given a specific combination of application and operating conditions. Reliability issues can be focused around: a) packaging optimization, b) manufacturing tolerances and c) selecting the right vendor to do the job. Further, the ability to receive adequate forms of cooling from the aircraft (if not otherwise constrained and if cooling margins permit) to power electronics will also be discussed as an obvious and significant driver in maintaining high reliability and integrity in more demanding (and higher power) applications. Trade assessments that can occur with specific generator electronics will be discussed at a non-specific, and generalized, level. The main body of the paper will be concluded with a discussion on the potential application of WBG technology in a variety of applications mentioned for aircraft while pointing out unique aspects that may be relevant in the future adoption of this technology. Finally, a conclusion will be provided reiterating various points throughout the paper and areas of potential follow-on activity.
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Cai, Zhiwei, Toby S. Scott-Ward, and David N. Sheppard. "Voltage-dependent Gating of the Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channel." Journal of General Physiology 122, no. 5 (2003): 605–20. http://dx.doi.org/10.1085/jgp.200308921.
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When excised inside-out membrane patches are bathed in symmetrical Cl−-rich solutions, the current-voltage (I-V) relationship of macroscopic cystic fibrosis transmembrane conductance regulator (CFTR) Cl− currents inwardly rectifies at large positive voltages. To investigate the mechanism of inward rectification, we studied CFTR Cl− channels in excised inside-out membrane patches from cells expressing wild-type human and murine CFTR using voltage-ramp and -step protocols. Using a voltage-ramp protocol, the magnitude of human CFTR Cl− current at +100 mV was 74 ± 2% (n = 10) of that at −100 mV. This rectification of macroscopic CFTR Cl− current was reproduced in full by ensemble currents generated by averaging single-channel currents elicited by an identical voltage-ramp protocol. However, using a voltage-step protocol the single-channel current amplitude (i) of human CFTR at +100 mV was 88 ± 2% (n = 10) of that at −100 mV. Based on these data, we hypothesized that voltage might alter the gating behavior of human CFTR. Using linear three-state kinetic schemes, we demonstrated that voltage has marked effects on channel gating. Membrane depolarization decreased both the duration of bursts and the interburst interval, but increased the duration of gaps within bursts. However, because the voltage dependencies of the different rate constants were in opposite directions, voltage was without large effect on the open probability (Po) of human CFTR. In contrast, the Po of murine CFTR was decreased markedly at positive voltages, suggesting that the rectification of murine CFTR is stronger than that of human CFTR. We conclude that inward rectification of CFTR is caused by a reduction in i and changes in gating kinetics. We suggest that inward rectification is an intrinsic property of the CFTR Cl− channel and not the result of pore block.
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Sharma, Roshan, and Masoud Karimi-Ghartemani. "Addressing Abrupt PV Disturbances, and Mitigating Net Load Profile’s Ramp and Peak Demands, Using Distributed Storage Devices." Energies 13, no. 5 (2020): 1024. http://dx.doi.org/10.3390/en13051024.
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At high penetration level of photovoltaic (PV) generators, their abrupt disturbances (caused by moving clouds) cause voltage and frequency perturbations and increase system losses. Meanwhile, the daily irradiation profile increases the slope in the net-load profile, for example, California duck curve, which imposes the challenge of quickly bringing on-line conventional generators in the early evening hours. Accordingly, this paper presents an approach to achieve two objectives: (1) address abrupt disturbances caused by PV generators, and (2) shape the net load profile. The approach is based on employing battery energy storage (BES) systems coupled with PV generators and equipped with proper controls. The proposed BES addresses these two issues by realizing flexible power ramp-up and ramp-down rates by the combined PV and BES. This paper presents the principles, modeling and control design aspects of the proposed system. A hybrid dc/ac study system is simulated and the effectiveness of the proposed BES in reducing the impacts of disturbances on both the dc and ac subsystems is verified. It is then shown that the proposed PV-BES modifies the daily load profile to mitigate the required challenge for quickly bringing on-line synchronous generators.
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Watanabe, Yasumasa, Alec Houpt, and Sergey Leonov. "Plasma-Assisted Control of Supersonic Flow over a Compression Ramp." Aerospace 6, no. 3 (2019): 35. http://dx.doi.org/10.3390/aerospace6030035.
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This study considers the effect of an electric discharge on the flow structure near a 19.4° compression ramp in Mach-2 supersonic flow. The experiments were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. The stagnation temperature and pressure were varied in a range of 294–600 K and 1–3 bar, respectively, to attain various Reynolds numbers ranging from 5.3 × 105 to 3.4 × 106 based on the distance between the exit of the Mach-2 nozzle and the leading edge of the ramp. Surface pressure measurements, schlieren visualization, discharge voltage and current measurements, and plasma imaging with a high-speed camera were used to evaluate the plasma control authority on the ramp pressure distribution. The plasma being generated in front of the compression ramp shifted the shock position from the ramp corner to the electrode location, forming a flow separation zone ahead of the ramp. It was found that the pressure on the compression surface reduced almost linearly with the plasma power. The ratio of pressure change to flow stagnation pressure was also an increasing function of the ratio of plasma power to enthalpy flux, indicating that the task-related plasma control effectiveness ranged from 17.5 to 25.
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Guo, Zhongjie, Lin Li, Ruiming Xu, et al. "High Consistency Ramp Design Method for Low Noise Column Level Readout Chain." Sensors 24, no. 21 (2024): 7057. http://dx.doi.org/10.3390/s24217057.
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In order to address the inconsistency problem caused by parasitic backend wiring among multiple ramp generators and among multiple columns in large-array CMOS image sensors (CIS), this paper proposes a high-precision compensation technology combining average voltage technology, adaptive negative feedback dynamic adjustment technology, and digital correlation double sampling technology to complete the design of an adaptive ramp signals inconsistency calibration scheme. The method proposed in this article has been successfully applied to a CIS with a pixel array of 8192(H) × 8192(V), based on the 55 nm 1P4M CMOS process, with a pixel size of 10×10μm2. The chip area is 88(H) × 89(V) mm2, and the frame rate is 10 fps. The column-level analog-to-digital converter is a 12-bit single-slope analog-to-digital converter (SS ADC). The experimental results show that the ramp generation circuit proposed in this paper can reduce the inconsistency among the ramp signals to 0.4% LSB, decreases the column fixed pattern noise (CFPN) caused by inconsistent ramps of each column to 0.000037% (0.015 e−), and increases the overall chip area and power consumption by only 0.6% and 0.5%, respectively. This method provides an effective solution to the influence of non-ideal factors on the consistency of ramp signals in large area array CIS.
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Subbarao, Mopidevi, Ch Sai Babu, S. Satyanarayana, and P. Chandra Babu Naidu. "Digital Fuzzy Current Mode Controlled Integrated PFC Converter with External Ramp Compensation." Journal of Circuits, Systems and Computers 27, no. 09 (2018): 1850147. http://dx.doi.org/10.1142/s0218126618501475.
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This paper propounded a novel method of design and realization of a digital fuzzy controlled buck integrated power factor correction (PFC) converter. It derives its advantages through the low buck capacitor voltage and single control switch (SW1), which leads to reduced complex control and price. Sub-harmonic oscillations generated in the peak current mode technique can be nullified by using the ramp signal, thereby improving the overall performance of the converter. The fuzzy logic controller (FLC) is robust and effective than the conventional linear controllers like P, PI, PID. In this paper, the digital fuzzy current mode controlled integrated PFC converter with external ramp compensation signal for 100 W load operating in the universal range of voltage (90[Formula: see text]V–265[Formula: see text]V), 50[Formula: see text]Hz has been designed and implemented using MATLAB/Simulink, verified in hardware using the TMS320F2812 digital processor board, and the results are found to be complying with international regulatory standards (IEC 6100-3-2 and IEEE 519-1992).
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Gao, Zhiyuan, Yiming Zhou, Jiangtao Xu, Huiying Liu, and Jing Gao. "High Dynamic Range Low Distortion PWM Readout Method with Self-Adjusted Reference for Digital Pixel Sensors." Journal of Circuits, Systems and Computers 26, no. 10 (2017): 1750148. http://dx.doi.org/10.1142/s0218126617501481.
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This paper presents a modified pulse width modulation (PWM) readout method for DPS with block-based self-adjusted reference voltage to extend dynamic range (DR). In this scheme, pixel arrays are divided into blocks with the same size, and the exposure process consists of two periods. During the first exposure, block-based reference voltage is generated based on the average photocurrent within the block. In the second exposure, the generated voltage is used as the reference voltage for PWM readout. Then the quantization results are combined together to represent the luminance information. DR and peak signal-to-noise ratio (PSNR) were discussed with different images and integration time. Simulation results show that this scheme can achieve a DR of over 96[Formula: see text]dB with 8-bit memory and 8-bit ADC and 145[Formula: see text]dB with 12-bit memory and 12-bit ADC. It also has 28.98[Formula: see text]dB PSNR on average, better than 20.11[Formula: see text]dB in fixed reference voltage method and 17.25[Formula: see text]dB in ramp reference voltage method. Combining the feature of active pixel sensor (APS) and PWM readout, this scheme allows better DR but also obtains less distortion of the image reconstruction.
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Moritz, Anna T., Gregory Newkirk, Randall K. Powers, and Marc D. Binder. "Facilitation of Somatic Calcium Channels Can Evoke Prolonged Tail Currents in Rat Hypoglossal Motoneurons." Journal of Neurophysiology 98, no. 2 (2007): 1042–47. http://dx.doi.org/10.1152/jn.01294.2006.
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Voltage-dependent persistent inward currents (PICs) make an important contribution to the input-output properties of alpha motoneurons. PICs are thought to be mediated by membrane channels located primarily on the dendrites as evidenced by prolonged tail currents following the termination of a voltage step and by a clockwise hysteresis in the whole cell inward currents recorded in response to depolarizing then repolarizing voltage ramp commands. We report here, however, that voltage-clamp currents with these same features can be generated in isolated somatic membrane patches from rat hypoglossal motoneurons. Long-lasting (200–800 ms) tail currents after 1-s voltage-clamp pulses were observed in nucleated patches from 16 of 23 cells. Further, these somatic PICs display “facilitation” in response to conditioning depolarization as previously observed in whole cell recordings from intact neurons. Pharmacological tests suggest that the PICs were primarily mediated by Cav1 channels. Our results show that many of the features of persistent calcium currents recorded from intact motoneurons do not necessarily reflect a remote dendritic origin but can also be ascribed to the intrinsic properties of their Cav1 channels.
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Horn, Eric M., and Tony G. Waldrop. "Hypoxic Augmentation of Fast-Inactivating and Persistent Sodium Currents in Rat Caudal Hypothalamic Neurons." Journal of Neurophysiology 84, no. 5 (2000): 2572–81. http://dx.doi.org/10.1152/jn.2000.84.5.2572.
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Previous work from this laboratory has indicated that TTX-sensitive sodium channels are involved in the hypoxia-induced inward current response of caudal hypothalamic neurons. Since this inward current underlies the depolarization and increased firing frequency observed in these cells during hypoxia, the present study utilized more detailed biophysical methods to specifically determine which sodium currents are responsible for this hypoxic activation. Caudal hypothalamic neurons from ∼3-wk-old Sprague-Dawley rats were acutely dissociated and patch-clamped in the voltage-clamp mode to obtain recordings from fast-inactivating and persistent (noninactivating) whole cell sodium currents. Using computer-generated activation and inactivation voltage protocols, rapidly inactivating sodium currents were analyzed during normal conditions and during a brief (3–6 min) period of severe hypoxia. In addition, voltage-ramp and extended-voltage-activation protocols were used to analyze persistent sodium currents during normal conditions and during hypoxia. A polarographic oxygen electrode determined that the level of oxygen in this preparation quickly dropped to 10 Torr within 2 min of initiation of hypoxia and stabilized at <0.5 Torr within 4 min. During hypoxia, the peak fast-inactivating sodium current was significantly increased throughout the entire activation range, and both the activation and inactivation values ( V 1/2) were negatively shifted. Furthermore both the voltage-ramp and extended-activation protocols demonstrated a significant increase in the persistent sodium current during hypoxia when compared with normoxia. These results demonstrate that both rapidly inactivating and persistent sodium currents are significantly enhanced by a brief hypoxic stimulus. Furthermore the hypoxic-induced increase in these currents most likely is the primary mechanism for the depolarization and increased firing frequency observed in caudal hypothalamic neurons during hypoxia. Since these neurons are important in modulating cardiorespiratory activity, the oxygen responsiveness of these sodium currents may play a significant role in the centrally mediated cardiorespiratory response to hypoxia.
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Ren, Ming, Aaron L. Randolph, Claudia Alvarez-Baron, et al. "Experimental factors that impact CaV1.2 channel pharmacology—Effects of recording temperature, charge carrier, and quantification of drug effects on the step and ramp currents elicited by the “step-step-ramp” voltage protocol." PLOS ONE 17, no. 11 (2022): e0276995. http://dx.doi.org/10.1371/journal.pone.0276995.
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Background and purpose CaV1.2 channels contribute to action potential upstroke in pacemaker cells, plateau potential in working myocytes, and initiate excitation-contraction coupling. Understanding drug action on CaV1.2 channels may inform potential impact on cardiac function. However, literature shows large degrees of variability between CaV1.2 pharmacology generated by different laboratories, casting doubt regarding the utility of these data to predict or interpret clinical outcomes. This study examined experimental factors that may impact CaV1.2 pharmacology. Experimental approach Whole cell recordings were made on CaV1.2 overexpression cells. Current was evoked using a “step-step-ramp” waveform that elicited a step and a ramp current. Experimental factors examined were: 1) near physiological vs. room temperature for recording, 2) drug inhibition of the step vs. the ramp current, and 3) Ca2+ vs. Ba2+ as the charge carrier. Eight drugs were studied. Key results CaV1.2 current exhibited prominent rundown, exquisite temperature sensitivity, and required a high degree of series resistance compensation to optimize voltage control. Temperature-dependent effects were examined for verapamil and methadone. Verapamil’s block potency shifted by up to 4X between room to near physiological temperature. Methadone exhibited facilitatory and inhibitory effects at near physiological temperature, and only inhibitory effect at room temperature. Most drugs inhibited the ramp current more potently than the step current—a preference enhanced when Ba2+ was the charge carrier. The slopes of the concentration-inhibition relationships for many drugs were shallow, temperature-dependent, and differed between the step and the ramp current. Conclusions and implications All experimental factors examined affected CaV1.2 pharmacology. In addition, whole cell CaV1.2 current characteristics—rundown, temperature sensitivity, and impact of series resistance—are also factors that can impact pharmacology. Drug effects on CaV1.2 channels appear more complex than simple pore block mechanism. Normalizing laboratory-specific approaches is key to improve inter-laboratory data reproducibility. Releasing original electrophysiology records is essential to promote transparency and enable the independent evaluation of data quality.
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Bouamrane, Omar, Tajeddine Khalili, Ilham Tyass, et al. "Flying capacitors multilevel inverter: architecture, control and active balancing." E3S Web of Conferences 336 (2022): 00039. http://dx.doi.org/10.1051/e3sconf/202233600039.
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To improve efficiency and productivity of electric energy generators based on photovoltaic, wind or hybrid systems; several DC/AC conversion techniques have been developed and tested like multilevel inverters. Multilevel inverters are a performant solution for the ramp-up of converters. As soon as the DC supply voltage exceeds a few kV, it is necessary to combine switches, switching cells or converters. This paper presents a progressive study of an interesting type of these inverters namely flying capacitor multilevel inverters (FCMLI): architecture, evolutions, benefits and inconvenient. In fact, we processed 3-and 5-level FCMLI while presenting possible circuit schemes and simulation results on Matlab Simulink. Finally, a general formulation has been adopted and applied to a 17 level FCMLI.
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Li, Haoren, Yong Huang, Qingyu Meng, and Xun Wang. "Effect of Electrical Parameters on the Structure and Properties of Aluminum Foil Microarc Oxidation Film." Metals 14, no. 10 (2024): 1108. http://dx.doi.org/10.3390/met14101108.
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Through a three-factor, two-level orthogonal experiment, the effects of varying electrical parameters (voltage, frequency, and duty cycle) on the thickness, pressure resistance, corrosion resistance, morphology, and phase composition of the micro-arc oxidized film of aluminum foil in constant voltage mode were investigated. The aluminum foil was oxidized by micro-arc oxidation for 50 min. Eddy-current thickness gauges were used to measure the oxide film’s thickness, TV characterization testers were used to test the film’s resistance to pressure, kinetic potential polarization curves were used to examine the oxide film’s resistance to electrochemical corrosion, and SEM and XRD composition were used to examine the microstructures and phase compositions of the oxide films that were produced. The oxide film’s thickness was increased from 7 μm to 22 μm and the voltage was increased from 350 V to 450 V. The oxide film’s ramp-up time at a frequency and duty cycle of 2000 Hz and 15% could reach 3 s, and the resistance value could reach 98% of the micro-arc oxidation voltage. The oxide film’s icorr decreased by an order of magnitude at high voltage compared to low voltage and the Rp value increased by an order of magnitude, which improved the corrosion resistance. The oxide film’s thickness increased as the voltage increased. Meanwhile, SEM was used to enhance the corrosion resistance. The oxide film thickens as the voltage increases. At the same voltage, the oxide film with a high frequency and low duty cycle has the best voltage resistance. The oxide film generated under high-voltage conditions has regular and dense surface holes, the oxide film’s α-Al2O3 phase increases, and the corrosion resistance in the NaCl medium is enhanced.
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Paulenich III, John, and Murray S. Korman. "Demonstration of nonlinear tuning curve vibration response using a homemade analog sweep spectrum analyzer." Journal of the Acoustical Society of America 155, no. 3_Supplement (2024): A148. http://dx.doi.org/10.1121/10.0027117.
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A super-heterodyne sweep spectrum analyzer has been designed (using analog circuitry), built and tested to cover the 5 to 1000 Hz range. The analyzer employs a linear ramp voltage versus time, driving a voltage-controlled oscillator VCO that generates a sweep from 32.768 kHz to 33.768 kHz in 70 s. An analog AD734 multiplies the VCO signal by a sinusoidal signal (generated by a watch crystal 32.768 kHz oscillator). The “mixer” signal is low-pass filtered and amplified to generate a 5-1000 Hz swept tone using a 2-in. speaker. The accelerometer (mounted on a thin circular clamped acrylic plate) vibration response involves multiplying this signal by the VCO, then filtering this “mixer” signal using a 4-stage watch crystal ladder filter with a 1 Hz bandwidth. This signal is squared and low-pass filtered to generate the time (converted to frequency) vs. mean-squared voltage response on an oscilloscope. In the demonstration, 300 g of 6 mm diameter glass beads are supported by the 11.4 cm diam, 3.2 mm thick plate and upper rigid cylindrical wall column. The nonlinear tuning curve vibration response is recorded for various incremental drive amplitudes to demonstrate that the tuning curve resonant frequency significantly decreases with increasing drive amplitude.
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KANCHANA BHAASKARAN, V. S., and J. P. RAINA. "TWO-PHASE SINUSOIDAL POWER-CLOCKED QUASI-ADIABATIC LOGIC CIRCUITS." Journal of Circuits, Systems and Computers 19, no. 02 (2010): 335–47. http://dx.doi.org/10.1142/s0218126610006098.
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This paper presents the design and performance analysis of the dual-rail encoded and sense-amplifier structured 2N–2P, 2N–2N2P, IPGL and PFAL quasi-adiabatic circuits operated by two-phase sinusoidal power-clock sources. The energetics of these families are studied for varying power-clock voltages. The drivability characteristics are evaluated using capacitive loads. The performance validation is made through 8-bit and 16-bit adder circuits using an integrated power-clock generator. Optimal adiabatic gain values are achieved for 2N–2N2P and IPGL circuits across a wide frequency range. Energy recovery comparison between the four-phase ramp and two-phase sine power-clocks is made. The results demonstrate the efficiency of sinusoidal power clock at both the high and the low frequency ranges of operation. The circuits were designed using 180 nm CMOS technology.
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Han, Chongyang, Mark Estacion, Jianying Huang, et al. "Human Nav1.8: enhanced persistent and ramp currents contribute to distinct firing properties of human DRG neurons." Journal of Neurophysiology 113, no. 9 (2015): 3172–85. http://dx.doi.org/10.1152/jn.00113.2015.
Full textAbstract:
Although species-specific differences in ion channel properties are well-documented, little has been known about the properties of the human Nav1.8 channel, an important contributor to pain signaling. Here we show, using techniques that include voltage clamp, current clamp, and dynamic clamp in dorsal root ganglion (DRG) neurons, that human Nav1.8 channels display slower inactivation kinetics and produce larger persistent current and ramp current than previously reported in other species. DRG neurons expressing human Nav1.8 channels unexpectedly produce significantly longer-lasting action potentials, including action potentials with half-widths in some cells >10 ms, and increased firing frequency compared with the narrower and usually single action potentials generated by DRG neurons expressing rat Nav1.8 channels. We also show that native human DRG neurons recapitulate these properties of Nav1.8 current and the long-lasting action potentials. Together, our results demonstrate strikingly distinct properties of human Nav1.8, which contribute to the firing properties of human DRG neurons.
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Xu, Jiangtao, Jing Yu, Fujun Huang, and Kaiming Nie. "A 10-Bit Column-Parallel Single Slope ADC Based on Two-Step TDC with Error Calibration for CMOS Image Sensors." Journal of Circuits, Systems and Computers 24, no. 04 (2015): 1550054. http://dx.doi.org/10.1142/s0218126615500541.
Full textAbstract:
This paper presents a 10-bit column-parallel single slope analog-to-digital converter (SS ADC) with a two-step time-to-digital converter (TDC) to overcome the long conversion time problem in conventional SS ADC for high-speed CMOS image sensors (CIS). The time interval proportional to the input signal is generated by a ramp generator and a comparator, which is digitized by a two-step TDC consisting of coarse and fine conversions to achieve a high-precision time-interval measurement. To mitigate the impact of propagation delay mismatch, a calibration circuit is also proposed to calibrate the delay skew within -T/2 to T/2. The proposed ADC is designed in 0.18 μm CMOS process. The power dissipation of each column circuit is 232 μW at supply voltages of 3.3 V for the analog circuits and 1.8 V for the digital blocks. The post simulation results indicate that the ADC achieves a SNDR of 60.89 dB (9.82 ENOB) and a SFDR of 79.98 dB at a conversion rate of 2 MS/s after calibration, while the SNDR and SFDR are limited to 41.52 dB and 67.64 dB, respectively before calibration. The differential nonlinearity (DNL) and integral nonlinearity (INL) without calibration are +15.80/-15.29 LSB and +1.68/-15.34 LSB while they are reduced down to +0.75/-0.25 LSB and +0.76/-0.78 LSB with the proposed calibration.
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Lin, Yifeng, Jiawei Hu, Tong Wang, and Zengping Wang. "Impact Mechanisms of Commutation Failure Caused by a Sending-End AC Fault and Its Recovery Speed on Transient Stability." Electronics 12, no. 16 (2023): 3439. http://dx.doi.org/10.3390/electronics12163439.
Full textAbstract:
A sending-end AC fault may lead to commutation failure (CF) in a line-commutated converter high-voltage direct current (LCC-HVDC) system. In this paper, a theoretical analysis of the impact mechanisms of a CF and its recovery speed on the transient stability of a sending-end power system (TSSPS) is performed. Firstly, the models of the sending-end power system and DC power of CF are established; the ramp function is utilized to characterize the DC power recovery process. Secondly, the swing direction of the relative rotor angle caused by a sending-end AC fault is discussed, and the DC power flow method is employed to theoretically analyze the impacts of CF and its recovery speed on TSSPS. Next, the mathematic relations between parameters of the voltage-dependent current order limiter (VDCOL) and DC power recovery speed are further derived. It is concluded that the impacts of CF and its recovery speed on transient stability are related to the swing direction caused by a sending-end AC fault, the inertia of generators, and the location of the rectifier station. Finally, the theoretical analysis is validated by Kundur’s two-area system and IEEE 68-bus-based AC/DC asynchronous interconnection test power systems, respectively.