Fabrication of micro/nanostructured α-Fe2O3 hollow spheres: effect of electric field on the morphological, magnetic and photocatalytic properties

RSC Advances ◽  
2016 ◽  
Vol 6 (70) ◽  
pp. 65789-65798 ◽  
Author(s):  
Rich Kant ◽  
Neetesh Kumar ◽  
Viresh Dutta
Keyword(s):  
Electric Field ◽  
Spray Pyrolysis ◽  
Hollow Spheres ◽  
Photocatalytic Properties ◽  
Dc Voltage ◽  
Continuous Fabrication

Continuous fabrication of α-Fe2O3 hollow spheres with sponge like morphology using an electric field assisted (by applying DC voltage) continuous spray pyrolysis (CoSP) technique.

Joule Heating Induced Temperature Gradient Focusing for Microfluidic Concentration of Samples

2010 ◽  
Author(s):  
Zhengwei Ge ◽  
Chun Yang
Keyword(s):  
Temperature Gradient ◽  
Electric Field ◽  
Joule Heating ◽  
Field Experiments ◽  
Dc Voltage ◽  
Sample Concentration ◽  
Great Achievement ◽  
Temperature Gradient Focusing ◽  
Concentration Enhancement ◽  
High Frequency Ac

Microfluidic concentration of sample species is achieved using the temperature gradient focusing (TGF) in a microchannel with a step change in the cross-section under a pure direct current (DC) field or a combined alternating current (AC) and DC electric field. Experiments were carried out to study the effects of applied voltage, buffer concentration and channel size on sample concentration in the TGF processes. These effects were analyzed and summarized using a dimensionless Joule number that is introduced in this study. In addition, Joule number effect in the Poly-dimethylsiloxane (PDMS)/PDMS microdevice was compared with the PDMS/Glass microdevice. A more than 450-fold concentration enhancement was obtained within 75 seconds in the PDMS/PDMS microdevice. Results also showed that the high frequency AC electric field which contributes to produce the temperature gradient and reduces the required DC voltage for the sample concentration. The lower DC voltage has generated slower electroosmotic flow (EOF), which reduces the backpressure effect associated with the finite reservoir size. Finally, a more than 2500-fold concentration enhancement was obtained within 14 minutes in the PDMS/PDMS microdevice, which was a great achievement in this TGF technique using inherent Joule heating effects.

Large-scale synthesis of Au–WO3 porous hollow spheres and their photocatalytic properties

2017 ◽  
Vol 7 (17) ◽  
pp. 3702-3706 ◽  
Author(s):  
Chenying He ◽  
Xia Li ◽  
Yahui Li ◽  
Junfang Li ◽  
Guangcheng Xi
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Organic Pollutants ◽  
Hybrid Materials ◽  
Large Scale ◽  
Hollow Spheres ◽  
Photocatalytic Properties ◽  
Excellent Activity ◽  
Visible Light Photocatalytic

Uniform Au–WO3 porous hollow spheres have been synthesized on a large-scale by a general in situ reaction. The hybrid materials exhibit excellent activity for visible-light photocatalytic degradation of organic pollutants.

Preparation and photocatalytic properties of nanometer TiO2 thin films by improved ultrasonic spray pyrolysis

Rare Metals ◽  
2011 ◽  
Vol 30 (S1) ◽  
pp. 233-237 ◽  
Author(s):  
Da Li ◽  
Jun Zhang ◽  
Lexi Shao ◽  
Chaoyan Chen ◽  
Guiang Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Photocatalytic Properties ◽  
Tio2 Thin Films ◽  
Ultrasonic Spray

Discharge and Flashover Behavior in Oil-Paper

2020 ◽  
pp. 105-128
Keyword(s):  
Electric Field ◽  
Operating Conditions ◽  
Surface Discharge ◽  
Discharge Characteristics ◽  
Dc Voltage ◽  
Composite Field ◽  
Field Distortion ◽  
Lightning Impulse ◽  
Creeping Discharge ◽  
Paper Insulation

Due to special operating conditions, the valve side bushing of the converter transformer connected to the converter valve is subject to complex voltage excitation, including DC voltage, AC/DC composite voltage, lightning impulse overvoltage, or composite voltage of operating overvoltage and DC. Under the action of this complicated electric field, the oil-paper insulation of the valve-side bushing of the converter transformer is prone to electric field distortion due to charge accumulation, which causes a surface discharge, which will seriously cause the edge breakdown. At the same time, since the temperature in the converter transformer rises due to a large amount of loss during the operation of the transformer, creeping discharge is more likely to occur under the electrothermal composite field. Hence, it is significant to carry out research on the surface discharge characteristics of the oil-paper insulation on the valve side of the converter transformer under the electrothermal composite field.

scholarly journals Facile fabrication of porous BiVO4 hollow spheres with improved visible-light photocatalytic properties

RSC Advances ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 6395-6404 ◽  
Author(s):  
Jun Mao ◽  
Qian Wu ◽  
Feifei Tao ◽  
Wen Xu ◽  
Tianjie Hong ◽  
...  
Keyword(s):  
Visible Light ◽  
Porous Structure ◽  
Solution Method ◽  
Hollow Spheres ◽  
Bismuth Vanadate ◽  
Photocatalytic Properties ◽  
One Step ◽  
Facile Fabrication ◽  
Visible Light Photocatalytic

Bismuth vanadate (BiVO4) hollow spheres with porous structure have been successfully fabricated by a one-step wet solution method with no surfactant and template.

scholarly journals Statistical Study on Space Charge effects and Stage Characteristics of Needle-Plate Corona Discharge under DC Voltage

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2732 ◽  
Author(s):  
Disheng Wang ◽  
Lin Du ◽  
Chenguo Yao
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Corona Discharge ◽  
Discharge Process ◽  
Space Charge Effects ◽  
Discharge Characteristics ◽  
Charge Effects ◽  
Dc Voltage ◽  
Field Distributions ◽  
Space Charges

The air’s partial discharges (PD) under DC voltage are obviously affected by space charges. Discharge pulse parameters have statistical regularity, which can be applied to analyze the space charge effects and discharge characteristics during the discharge process. Paper studies air corona discharge under DC voltage with needle-plate model. Statistical rules of repetition rate (n), amplitude (V) and interval time (∆t) are extracted, and corresponding space charge effects and electric field distributions in PD process are analyzed. The discharge stages of corona discharge under DC voltage are divided. Furthermore, reflected space charge effects, electric field distributions and discharge characteristics of each stages are summarized to better explain the stage discharge mechanism. This research verifies that microcosmic process of PD under DC voltage can be described based on statistical method. It contributes to the microcosmic illustration of gas PD with space charges.

scholarly journals Evaluation of Electric Field and Space Charge Dynamics in Dielectric under DC Voltage with Superimposed Switching Impulse

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1836 ◽  
Author(s):  
Ik-Soo Kwon ◽  
Sun-Jin Kim ◽  
Mansoor Asif ◽  
Bang-Wook Lee
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Numerical Study ◽  
Numerical Approach ◽  
Dc Voltage ◽  
Charge Dynamics ◽  
Electrical Stress ◽  
Dc Stress

The influx of a switching impulse during DC steady-state operations causes severe electrical stress on the insulation of HVDC cables. Thus, the insulation should be designed to withstand a superimposed switching impulse. All major manufacturers of DC cables perform superimposed switching impulse breakdown tests for prequalification. However, an experimental approach to study space charge dynamics in dielectrics under a switching impulse superposed on DC voltage has not been reported yet. This is because, unlike the DC stress, it is not possible to study the charge dynamics experimentally under complex stresses, such as switching impulse superposition. Hence, in order to predict and investigate the breakdown characteristics, it is necessary to obtain accurate electric field distribution considering space charge dynamics using a numerical approach. Therefore, in this paper, a numerical study on the switching impulse superposition was carried out. The space charge dynamics and its distribution within the dielectric under DC stress were compared with those under a superimposed switching impulse using a bipolar charge transport (BCT) model. In addition, we estimated the effect of a superimposed switching impulse on a DC electric field distribution. It was concluded that the temperature conditions of dielectrics have a significant influence on electric field and space charge dynamics.

Study on Electric Field Characteristics of Converter Transformer on Valve Side Winding

2011 ◽  
Vol 130-134 ◽  
pp. 1413-1417
Author(s):  
You Hua Gao ◽  
Guo Wei Liu ◽  
Yan Bin Li ◽  
You Feng Gao
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
High Voltage ◽  
Electric Field Distribution ◽  
Influence Factors ◽  
Calculation Model ◽  
Dc Voltage ◽  
Voltage Polarity ◽  
Transient Electric Field

Numerical calculation model with compound insulation of transient electric field is given. The insulation is more prominent due to complication for voltage applied on valve side winding of the converter transformer. So the simplied structure for electric calculation on the valve side winding of the converter transformer is established. The electric field distribution characteristics on the valve side winding of the converter transformer is analyzed and electric fields in different resistivity and permittivity are calculated under AC high voltage, DC high voltage, AC superimposed DC voltage, polarity reversal voltage. The maximum electric field intensity is calculated and analyzed under kinds of high voltage. Some important influence factors for electric field distribution are also discussed in this paper.

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