constant current
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Author(s):  
Mustapha El Alaoui ◽  
Karim El Khadiri ◽  
Rachid El Alami ◽  
Ahmed Tahiri ◽  
Ahmed Lakhssassi ◽  
...  

A new Li-Ion battery charger interface (BCI) using pulse control (PC) technique is designed and analyzed in this paper. Thanks to the use of PC technique, the main standards of the Li-Ion battery charger, i.e. fast charge, small surface area and high efficiency, are achieved. The proposed charger achieves full charge in forty-one minutes passing by the constant current (CC) charging mode which also included the start-up and the constant voltage mode (CV) charging mode. It designed, simulated and layouted which occupies a small size area 0.1 mm2 by using Taiwan Semiconductor Manufacturing Company 180 nm complementary metal oxide semi-conductor technology (TSMC 180 nm CMOS) technology in Cadence Virtuoso software. The battery voltage VBAT varies between 2.9 V to 4.35 V and the maximum battery current IBAT is 2.1 A in CC charging mode, according to a maximum input voltage VIN equal 5 V. The maximum charging efficiency reaches 98%.


Author(s):  
Hongwei Li ◽  
Xiao Wang ◽  
Junmu Lin ◽  
Lei Wu ◽  
Tong Liu

Purpose This study aims to provide a solution of the power flow calculation for the low-voltage ditrect current power grid. The direct current (DC) power grid is becoming a reliable and economic alternative to millions of residential loads. The power flow (PF) in the DC network has some similarities with the alternative current case, but there are important differences that deserve to be further concerned. Moreover, the dispatchable distributed generators (DGs) in DC network can realize the flexible voltage control based on droop-control or virtual impedance-based methods. Thus, DC PF problems are still required to further study, such as hosting all load types and different DGs. Design/methodology/approach The DC power analysis was explored in this paper, and an improved Newton–Raphson based linear PF method has been proposed. Considering that constant impedance (CR), constant current (CI) and constant power (CP) (ZIP) loads can get close to the practical load level, ZIP load has been merged into the linear PF method. Moreover, DGs are much common and can be easily connected to the DC grid, so V nodes and the dispatchable DG units with droop control have been further taken into account in the proposed method. Findings The performance and advantages of the proposed method are investigated based on the results of the various test systems. The two existing linear models were used to compare with the proposed linear method. The numerical results demonstrate enough accuracy, strong robustness and high computational efficiency of the proposed linear method even in the heavily-loaded conditions and with 10 times the line resistances. Originality/value The conductance corresponding to each constant resistance load and the equivalent conductance for the dispatchable unit can be directly merged into the self-conductance (diagonal component) of the conductance matrix. The constant current loads and the injection powers from dispatchable DG units can be treated as the current sources in the proposed method. All of those make the PF model much clear and simple. It is capable of offering enough accuracy level, and it is suitable for applications in DC networks that require a large number of repeated PF calculations to optimize the energy flows under different scenarios.


Diversity ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 51
Author(s):  
Valentina A. Bracchi ◽  
Sarah Caronni ◽  
Agostino N. Meroni ◽  
Esteban Gottfried Burguett ◽  
Fabrizio Atzori ◽  
...  

Mediterranean rhodolith beds are priority marine benthic habitats for the European Community, because of their relevance as biodiversity hotspots and their role in the carbonate budget. Presently, Mediterranean rhodolith beds typically occur within the range of 30–75 m of water depth, generally located around islands and capes, on flat or gently sloping areas. In the framework of a collaboration between the University of Milano-Bicocca and the Marine Protected Area “Capo Carbonara” (Sardinia, Italy), video explorations and sampling collections in three selected sites revealed the occurrence of a well developed and heterogeneous rhodolith bed. This bed covers an area >41 km2 around the cape, with live coverage ranging between 6.50 and 55.25%. Rhodoliths showed interesting morphostructural differences. They are small compact pralines at the Serpentara Island, associated with gravelly sand, or bigger boxwork at the Santa Caterina shoal associated with sand, whereas branches are reported mostly in the Is Piscadeddus shoal, associated with muddy sand. Both in the Santa Caterina shoal and the Serpentara Island, rhodoliths generally show a spheroidal shape, associated with a mean value of currents of 4.3 and 7.3 cm/s, respectively, up to a maximum of 17.7 cm/s at Serpentara, whereas in the Is Piscadeddus shoal rhodolith shape is variable and current velocity is significantly lower. The different hydrodynamic regime, with a constant current directed SW, which deviates around the cape towards E, is responsible for such morphostructural heterogeneity, with the site of the Serpentara Island being the most exposed to a constant unidirectional and strong current. We can associate current velocity with specific rhodolith morphotypes. The morphostructural definition of the heterogeneity of rhodoliths across large beds must be considered for appropriate management policies.


2022 ◽  
pp. 136943322110737
Author(s):  
Nariman Fouad ◽  
Mohamed A Saifeldeen

This article proposes a new technique of monitoring neutral axis positions and deflection of Reinforced Concrete (RC) beam during corrosion of steel reinforcement using macro-strain measurements of distributed long-gauge sensors. A different group of distributed long-gauge Packaged Carbon Fiber Line (PCFL) sensors with self-compensation and effective packaging system is installed on the compression and tension fibers of the concrete surface and steel reinforcements of RC beam to verify the proposed method experimentally. An accelerated corrosion method utilizing a salt solution and the constant current was used to achieve the required corrosion levels. The estimated deflection measured by the developed method is compared with the results using Linear Variable Displacement Transducer (LVDTs). It has been demonstrated that long-gauge PCFL sensors could provide the same accuracy. The distributed measured strains were utilized to evaluate the deterioration of the structure’s health with the advance of corrosion. Based on corrosion monitoring experimental results, it can be confirmed that using distributed PCFL sensors mounted on steel reinforcements or concrete surface, the locations and progress of the damage with corrosion time can be detected effectively. The maximum error in the estimated deflection from PCFL sensors mounted on the concrete surface compared to the LVDTs before the onset and after 24 h of accelerated corrosion was 0.5% and 2.5%, respectively.


2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Michael Schweigmann ◽  
Frank Kirchhoff ◽  
Klaus P. Koch

Abstract Decoding the cellular network interaction of neurons and glial cells are important in the development of new therapies for diseases of the central nervous system (CNS). Electrophysiological in vivo studies in mice will help to understand the highly complex network. In this paper, the optimization of epidural liquid crystal polymer (LCP) electrodes for different platinum electroplating parameters are presented and compared. Constant current and pulsed current electroplating varied in strength and duration was used to decrease the electrode impedance and to increase the charge storage capacity (CSCC). In best cases, both methods generated similar results with an impedance reduction of about 99%. However, electroplating with pulsed currents was less parameter-dependent than the electroplating with constant current. The use of ultrasound was essential to generate platinum coatings without plating defects. Electrode model parameters extracted from the electrode impedance reflected the increase in surface porosity due to the electroplating processes.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 531
Author(s):  
Tiago Coelho-Magalhães ◽  
Emerson Fachin-Martins ◽  
Andressa Silva ◽  
Christine Azevedo Coste ◽  
Henrique Resende-Martins

Since the first Cybathlon 2016, when twelve teams competed in the FES bike race, we have witnessed a global effort towards the development of stimulation and control strategies to improve FES-assisted devices, particularly for cycling, as a means to practice a recreational physical activity. As a result, a set of technical notes and research paved the way for many other studies and the potential behind FES-assisted cycling has been consolidated. However, engineering research needs instrumented devices to support novel developments and enable precise assessment. Therefore, some researchers struggle to develop their own FES-assisted devices or find it challenging to implement their instrumentation using commercial devices, which often limits the implementation of advanced control strategies and the possibility to connect different types of sensor. In this regard, we hypothesize that it would be advantageous for some researchers in our community to enjoy access to an entire open-source FES platform that allows different control strategies to be implemented, offers greater adaptability and power capacity than commercial devices, and can be used to assist different functional activities in addition to cycling. Hence, it appears to be of interest to make our proprietary electrical stimulation system an open-source device and to prove its capabilities by addressing all the aspects necessary to implement a FES cycling system. The high-power capacity stimulation device is based on a constant current topology that allows the creation of biphasic electrical pulses with amplitude, width, and frequency up to 150 mA, 1000 µs, and 100 Hz, respectively. A mobile application (Android) was developed to set and modify the stimulation parameters of up to eight stimulation channels. A proportional-integral controller was implemented for cadence tracking with the aim to improve the overall cycling performance. A volunteer with complete paraplegia participated in the functional testing of the system. He was able to cycle indoors for 45 min, accomplish distances of more than 5 km using a passive cycling trainer, and pedal 2400 m overground in 32 min. The results evidenced the capacity of our FES cycling system to be employed as a cycling tool for individuals with spinal cord injury. The methodological strategies used to improve FES efficiency suggest the possibility of maximizing pedaling duration through more advanced control techniques.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinmao Tian ◽  
Yuhua Shi ◽  
Yifeng Zhang ◽  
Yijie Wang ◽  
Mengke Li ◽  
...  

AbstractThe posterior pallial amygdala (PoA) is located on the basolateral caudal telencephalon, including the basal division of PoA (PoAb) and the compact division of PoA (PoAc). PoA plays a vital role in emotion regulation and is considered a part of the amygdala in birds. However, the regulatory functions responsible for motor behaviors and emotions between PoAb and PoAc are poorly understood. Therefore, we studied the structure and function of PoA by tract-tracing methods, constant current electrical stimulation, and different dopamine receptor drug injections in pigeons (Columba livia domestica). PoAb connects reciprocally with two nuclear groups in the cerebrum: 1) a continuum comprising the temporo–parieto–occipitalis, corticoidea dorsolateralis, hippocampus, and parahippocampalis areas and 2) rostral areas of the hemisphere, including the nucleus septalis lateralis and nucleus taeniae amygdalae. Extratelencephalic projections of PoAb terminate in the lateral hypothalamic nucleus and are scattered in many limbic midbrain regions. PoAb and PoAc mainly mediated the turning movement. In the ‘open-field’ test, D1 agonist and D2 antagonist could significantly reduce the latency period for entering into the central area and increase the residence time in the central area, whereas D1 antagonist and D2 agonist had the opposite effect. PoAb and PoAc are important brain areas that mediate turning behavior.


Author(s):  
Nicholas Schwartz ◽  
Jason Harrington ◽  
Kirk J Ziegler ◽  
Philip Cox

Abstract The direct electrochemically driven separation of CO2 from a humidified N2, O2, and CO2 gas mixture was conducted using an asymmetric membrane electrode assembly (MEA). The MEA was fabricated using a screen-printed ionomer bound Pt cathode, an anion exchange membrane (AEM), and ionomer bound IrO2 anode. Electrocatalyst materials were physically and chemically characterized prior to inclusion within the electrode. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements using a rotating disk electrode (RDE) were used to quantify the catalytic activity and determine the effects of the catalyst-to-ionomer ratio. Catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface analysis, and (dynamic light scattering) DLS to evaluate catalyst structure, active surface area, and determine the particle size and bulk particle size distribution (PSD). The electrocatalyst layer of the electrodes were fabricated by screen printing a uniformly dispersed mixture of catalyst, dissolved anionic ionomer, and a solvent system onto an electrode supporting gas diffusion layer (GDL). Pt IrO2 MEAs were fabricated and current-voltage relationships were determined using constant-current measurements over a range of applied current densities and flow rates. Baseline reaction kinetics for CO2 separation were established with a standard set of Pt-IrO2 MEAs.


Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 175
Author(s):  
Jinlei Chen ◽  
Sheng Wang ◽  
Carlos E. Ugalde-Loo ◽  
Wenlong Ming ◽  
Oluwole D. Adeuyi ◽  
...  

Although the control of modular multi-level converters (MMCs) in high-voltage direct-current (HVDC) networks has become a mature subject these days, the potential for adverse interactions between different converter controls remains an under-researched challenge attracting the attention from both academia and industry. Even for point-to-point HVDC links (i.e., simple HVDC systems), converter control interactions may result in the shifting of system operating voltages, increased power losses, and unintended power imbalances at converter stations. To bridge this research gap, the risk of multiple cross-over of control characteristics of MMCs is assessed in this paper through mathematical analysis, computational simulation, and experimental validation. Specifically, the following point-to-point HVDC link configurations are examined: (1) one MMC station equipped with a current versus voltage droop control and the other station equipped with a constant power control; and (2) one MMC station equipped with a power versus voltage droop control and the other station equipped with a constant current control. Design guidelines for droop coefficients are provided to prevent adverse control interactions. A 60-kW MMC test-rig is used to experimentally verify the impact of multiple crossing of control characteristics of the DC system configurations, with results verified through software simulation in MATLAB/Simulink using an open access toolbox. Results show that in operating conditions of 650 V and 50 A (DC voltage and DC current), drifts of 7.7% in the DC voltage and of 10% in the DC current occur due to adverse control interactions under the current versus voltage droop and power control scheme. Similarly, drifts of 7.7% both in the DC voltage and power occur under the power versus voltage droop and current control scheme.


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