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Direct current

About: Direct current is a research topic. Over the lifetime, 41225 publications have been published within this topic receiving 225694 citations. The topic is also known as: DC.


Papers
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Journal ArticleDOI
24 Sep 2010-Science
TL;DR: Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces, and capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.
Abstract: Electric double-layer capacitors (DLCs) can have high storage capacity, but their porous electrodes cause them to perform like resistors in filter circuits that remove ripple from rectified direct current. We have demonstrated efficient filtering of 120-hertz current with DLCs with electrodes made from vertically oriented graphene nanosheets grown directly on metal current collectors. This design minimized electronic and ionic resistances and produced capacitors with RC time constants of less than 200 microseconds, in contrast with ~1 second for typical DLCs. Graphene nanosheets have a preponderance of exposed edge planes that greatly increases charge storage as compared with that of designs that rely on basal plane surfaces. Capacitors constructed with these electrodes could be smaller than the low-voltage aluminum electrolyte capacitors that are typically used in electronic devices.

1,233 citations

Journal ArticleDOI
Mamoru Omori1
TL;DR: In this paper, the graphite die set in a spark plasma system (SPS) is heated by a pulse direct current, which induces good effects on materials in the die.
Abstract: The graphite die set in spark plasma system (SPS) is heated by a pulse direct current. Weak plasma, discharge impact, electric field and electric current, which are based on this current, induce good effects on materials in the die. The surface films of aluminum and pure WC powders are ruptured by the spark plasma. Pure AlN powder is sintered without sintering additives in the electric field. The spark plasma leaves discharge patterns on insulators. Organic fibers are etched by the spark plasma. Thermosetting polyimide is consolidated by the spark plasma. Insoluble polymonomethylsilane is rearranged into the soluble one by the spark plasma. A single crystal of CoSb3 is grown from the compound powders in the electric field by slow heating. Coupled crystals of eutectic powder are connected with each other in the electric field.

953 citations

Patent
03 Nov 1994
TL;DR: In this paper, a monitoring circuit for an electrosurgical generator has active and return output conductors, and feedback modifies the output when the adders determine the power applied to the load (12) in real time.
Abstract: A monitoring circuit (10) for an electrosurgical generator (11) has active and return output conductors. Voltage, current (24) and the inverse of current (24) picked up inductively are provided to adder circuits for summing the picked up voltage (20) and current (24) and computing the difference of the picked up voltage (20) and the current (24). Root mean square to direct current converters (26 and 28) signal RMS average values of the sum and difference. A microprocessor squares the values and applies them to a formula wherein the sum signals (22) have subtracted therefrom the difference signals (25); the results are divided by four to provide the root mean square of the power applied to the load (12). During desiccation the output is regulated in response to impedance to shut off output. A diagnostic circuit relates impedance load and output response during operation to a look up table or a microprocessor algorithm to calibrate. Feedback modifies the output when the adders determine the power applied to the load (12) in real time. A method has generator output to active and return conductors (14 and 15) and to inductive pick ups (16 and 17) for voltage and current (24), computes sum and differential values (25), changes root mean square to direct currents (24), squares the values and subtracts the differential from the summation, then divides the result finding the root mean square value of the power.

876 citations

Journal ArticleDOI
TL;DR: In this paper, the authors directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current, which can be tuned over a range of several gigahertz by varying the applied current.
Abstract: We have directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current The precession frequency can be tuned over a range of several gigahertz by varying the applied current The frequencies of excitation also vary with applied field, resulting in a microwave oscillator that can be tuned from below 5 to above 40 GHz This novel method of inducing high-frequency dynamics yields oscillations having quality factors from 200 to 800 We compare our results with those from single-domain simulations of current-induced dynamics

799 citations

Book
01 Jan 1972
TL;DR: In this paper, the basic concepts of a Power System Control of Power and Frequency Control of Voltage and Reactive Power Load Flows Fault Analysis Stability Limits Direct Current Transmission Overvoltages and Insulation Requirements Overhead Lines and Underground Cables Protection Appendices Index.
Abstract: Basic Concepts Components of a Power System Control of Power and Frequency Control of Voltage and Reactive Power Load Flows Fault Analysis Stability Limits Direct Current Transmission Overvoltages and Insulation Requirements Overhead Lines and Underground Cables Protection Appendices Index.

757 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202377
2022168
2021541
20201,629
20192,287
20182,615