Advances in Numerical and Experimental Study of Dielectrophoretic Assembly of Carbon Nanotubes

2013 ◽  
Vol 745-746 ◽  
pp. 430-435 ◽  
Author(s):  
Shao Hua Zhen ◽  
Li Bao An ◽  
Yan Yan Liu
Keyword(s):  
Carbon Nanotubes ◽  
Experimental Study ◽  
Field Strength ◽  
Electric Field ◽  
Field Gradient ◽  
High Precision ◽  
Applied Voltage ◽  
Electrode Spacing ◽  
Assembly Process ◽  
Assembly Time

Study of the effect of dielectrophoresis (DEP) parameters is important in high-precision DEP assembly of carbon nanotubes (CNTs). The DEP parameters usually considered in the literature include the magnitude and frequency of the applied voltage, the assembly time, the concentration of the CNT suspension, and the geometry of the electrodes. This paper reviews the current progresses on both numerical and experimental study of the CNT assembly by DEP, especially the influence of the DEP parameters on the assembly process and results. The review shows that the magnitude of the applied voltage affects the DEP force and the number of deposited CNTs. The assembly time and CNT concentration influence the density of deposited CNTs. Different electrode geometries have an effect on the distribution of the electric field. The electrode spacing changes the field strength and the direction of the field gradient. The related discussion is presented as well.

Experimental Study of Melt Electrospinning in Parallel Electrical Field

2011 ◽  
Vol 221 ◽  
pp. 111-116 ◽  
Author(s):  
Ming Feng Hao ◽  
Yong Liu ◽  
Xue Tao He ◽  
Peng Cheng Xie ◽  
Wei Min Yang
Keyword(s):  
Experimental Study ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Melt Spinning ◽  
Fiber Diameter ◽  
The Other ◽  
Electrical Field ◽  
Melt Electrospinning ◽  
Plate Area

In this paper, self-designed electrospinning equipment was used to make a series of electrospinning experiments with materials of polypropylene. The influences of the receiver area, the upper plate area, and the overlapping area between the receiver and the upper plate, on the melt spinning electric field, the spinning efficiency, and the fiber diameter, were investigated respectively. The results showed that when the other parameters were kept unchanged, with the increase of the receiver’s diameter, the electric field strength and spinning efficiency increased, and the fiber diameter increased at first and then decreased; the bigger the overlapping area between the receiver and the upper plate, the more stable the vertical spinning path.

Timing with PMTs

2017 ◽  
Author(s):  
A. G. Wright
Keyword(s):  
Monte Carlo ◽  
Field Strength ◽  
Monte Carlo Simulations ◽  
Field Gradient ◽  
Electric Fields ◽  
Electrode Spacing ◽  
Electron Motion ◽  
Zero Crossing ◽  
Time Dispersion ◽  
Initial Electron Energy

The timing capability of photomultipliers (PMTs) can be inferred from the basic laws of electron motion. The relationships between time dispersion and field strength, initial electron energy, angle of emission, and electrode spacing follow from these laws. For conventional PMTs, the major contribution to dispersion arises from the cathode-to-first-dynode region. The field gradient at the cathode primarily determines the timing. This is verified by examining the electron motion in non-uniform electric fields. The contribution from interdynode transitions is small for linear focussed PMTs. Monte Carlo simulations of output waveforms from scintillators agree with measurements. The performance of threshold, zero crossing, and constant fraction (CF) discriminators is examined, revealing the superiority of the CF types. Two organizations have made detailed timing measurements, some of which show sub-nanosecond jitter. Proximity focussed PMTs from Hamamatsu confirm time dispersion measured in picoseconds.

Experimental Study of the Electric Field Gradient in In5Bi3

1982 ◽  
Vol 74 (2) ◽  
pp. 661-666 ◽  
Author(s):  
S. G. Fries ◽  
J. A. H. da Jornada ◽  
A. Maciel
Keyword(s):  
Experimental Study ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient

scholarly journals Method for measuring intensity of inhomogeneous electrical fields by average value

2021 ◽  
pp. 67-74
Author(s):  
S. V. Biryukov ◽  
◽  
L. V. Tyukina ◽  
A. V. Tyukin ◽  
◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
High Precision ◽  
Measurement Method ◽  
Measurement Methods ◽  
New Method ◽  
Average Value ◽  
True Value

Measurement and control of the intensity levels of inhomogeneous electric fields with high accuracy is quite a difficult task. The solution to this problem is connected both with the development of new sensors and methods for measuring the electric field strength. The creation of new high-precision electrical induction sensors has exhausted its capabilities at the current level of technology and technology. Therefore, new ideas are needed for solving the problems of high-precision measurement of the electric field strength. One of these ways is the development of new measurement methods. Existing measurement methods characterized by the complexity of the measurement processes, suitability in some cases, and unsuitability in others, do not provide the desired metrological characteristics. Therefore, the work related to the development of methods for measuring the intensity of inhomogeneous electric fields does not stand still, and is relevant. The aim of the study is to create a new method for measuring the strength of electric fields using known sensors, which makes it possible to significantly reduce the error in measuring inhomogeneous electric fields. The idea of constructing a new measurement method is formed. The idea of the method is that in the presence of two physical quantities measured with different sign values of the error, the average value of the physical quantity will always be closer to the true value. Based on this, a new method for measuring the intensity of inhomogeneous electric fields is proposed, associated only with the original measurement process. The measurement method id named «Average value method» (MSZ). The estimation of the error of this method shows a decrease in the measurement error to +5 % with the full spatial measurement range 0a1. Using the «Average value method» it is possible to achieve a significant increase in the accuracy of measuring the strength of inhomogeneous electric fields in a wide spatial range of measurements in comparison with known methods

Concept of the Tip Effect in Single Walled Carbon Nanotube

2015 ◽  
Vol 1099 ◽  
pp. 37-40
Author(s):  
Khalil El-Hami ◽  
Abdelkhalak El-Hami
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electrical Properties ◽  
Field Strength ◽  
Electric Field ◽  
Surface Charge Density ◽  
Geometrical Parameters ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Field Lines

In this investigation, we reported that single walled carbon nanotube can act as a sharpest tip where the electric field strength is highly concentrated at the edge. Therefore, we study the effects of the physical and geometrical parameters of an applied electric field gradient to various electrode structures. Results showed that carbon nanotubes presented a strongest electric field value at the edge which makes them suited for applications as unidirectional electric field or serving as nanoelectrode with a diameter of about one nanometer to be used for conductivity nanotest and to determine the electrical properties of single molecules or clusters.Keywords: single walled carbon nanotube, nan-electrode, tip, electric field lines, surface charge density.

scholarly journals An Experimental Study of the Crystallinity of Different Density Polyethylenes on the Breakdown Characteristics and the Conductance Mechanism Transformation under High Electric Field

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2657 ◽  
Author(s):  
Liwei Zhou ◽  
Xuan Wang ◽  
Yongqi Zhang ◽  
Peng Zhang ◽  
Zhi Li
Keyword(s):  
Experimental Study ◽  
Field Strength ◽  
Electric Field ◽  
High Field ◽  
High Electric Field ◽  
Low Density Polyethylene ◽  
Breakdown Field ◽  
Low Density ◽  
High Field Strength ◽  
Continuous Increase

In order to study the crystallinity of different density polyethylenes, this paper conducts an experimental study on the transformation of the conductance mechanism under a high electric field. In this experiment, X-ray diffraction (XRD), differentials scanning calorimetry (DSC), direct current (DC) breakdown of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE) and high-density polyethylene (HDPE), as well as the conductivity characteristics under an electric field of 5–200 kV/mm are tested. In addition, the electric field–current density curves of the four kinds of polyethylene are fitted to analyze their conductance transition in non-ohmic regions under different high field strengths, through applying the mathematical formula of a variety of conductance mechanisms. The experimental results are as follows: as the density of polyethylene increases, the crystallinity increases continuously. Moreover, the continuous increase of crystallinity causes the electric conduction flow under the same field strength to decrease significantly. The field strength corresponding to the two turning points in the conductance characteristic curve increases simultaneously, and the breakdown field strength increases accordingly; through analysis, it is found that in the high field, as the electric field increases, the conductance mechanism develops from the ohmic conductance of the low field strength region to the bulk effect of the high field strength region (Poole–Frenkel effect). Then, it develops into the electrode effect to the high field strength (Schottky effect), although the threshold field strength of this conductance mechanism transition increases with the increase of crystallinity.

Experimental Study of Small Diffusion Flame Under Strong Electric Field

2008 ◽  
Author(s):  
Zeliang Yang ◽  
Jing Cheng ◽  
Tao Xu ◽  
Yunhua Gan
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Electric Field ◽  
Diffusion Flame ◽  
Strong Electric Field ◽  
Ethanol Vapor ◽  
Electrode Spacing ◽  
Small Diffusion ◽  
Inner Diameter ◽  
Combustion Tests

The study of micro flame is very important for the design of an efficient, safe micro-burner. An experimental study of small jet diffusion flame was performed. Combustion tests under strong electric field were carried out in ceramic tube burners with the inner diameter of 1.0mm using liquid ethanol as fuel. The relationship between flame dimension and Reynolds number with the voltage was analyzed experimentally. The experiments were conducted with the voltage ranging from 0V to 10000V, and with different electrode spacing (3cm, 5cm, 7cm). The experimental results show that under electric field, the Reynolds number of ethanol vapor increases with increasing the voltage. And the Reynolds number may become instable when the electrode spacing is too large. A strong electric field can reduce soot emission from the flame.

AC Electric Field-Induced Alignment and Long-Range Assembly of Multi-Wall Carbon Nanotubes Inside Aqueous Media

2007 ◽  
Vol 7 (12) ◽  
pp. 4322-4332 ◽  
Author(s):  
Zhihui Guo ◽  
Jeffery A. Wood ◽  
Krista L. Huszarik ◽  
Xiaohu Yan ◽  
Aristides Docoslis
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Resistivity ◽  
Carbon Nanotube ◽  
Electric Field ◽  
Long Range ◽  
Applied Voltage ◽  
Three Dimensional ◽  
Field Frequency ◽  
Ac Electric Field ◽  
Ac Field

The present work examines the behavior of multiwall carbon nanotubes (MWCNT) inside AC electric fields created by three-dimensional electrodes. The response of carbon nanotubes stably suspended in water with the aid of a nonionic surfactant is monitored by combining microscopic observations with on-line measurements of the suspension resistivity. It is found that polarization effects induced by the externally applied AC electric field on MWCNTs can cause their unidirectional orientation and end-to-end contact that result in formations of spatially distributed, long-range, three-dimensional and electrically conducting structures that span the entire gap between the electrodes. The length of the formed structures, which in the present case was approximately 30 times larger than that of an individual carbon nanotube, can be controlled by adjusting the spacing between the electrodes. The influence of main experimental parameters, namely, MWCNT concentration, applied voltage, AC field frequency, and electrode surface topography on the suspension behavior is experimentally examined. Results are demonstrated for applied voltage values, AC field frequencies, and carbon nanotube concentrations in the range 4–40 Vptp, 10 Hz–5 MHz, and 0.001–2.0 wt%, respectively. While higher electric field strengths accelerate the formation of aligned structures, higher frequency values were found to result in suspensions that exhibit smaller electrical resistivity. Carbon nanotube dispersions exposed to an AC electric field exhibit a 100-fold or more decrease in their electrical resistivity, even when carbon nanotube concentrations as low as 0.005 wt% are used.

Tube Bus Corona Optimal Design of HVDC Converter Substation

2010 ◽  
Vol 139-141 ◽  
pp. 1384-1387 ◽  
Author(s):  
Ming Ming Xu ◽  
Ke Jun Li ◽  
Lin Niu ◽  
Min Liu ◽  
Zhi Hong Guo
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electrode Spacing ◽  
Voltage Gradient ◽  
Electromagnetic Environment ◽  
Characteristic Parameters ◽  
Calculation Results ◽  
Onset Voltage ◽  
Main Factor

The corona characteristic of HVDC tube bus is the main factor taken into account for choosing tube bus of HVDC converter substation. The intension of corona could affect the electromagnetic environment of converter station and generate audible noise. By establishing the calculation models of electric field strength along the tube bus surface and the electric field strength on ground, the paper computes the corona onset voltage gradient and gives the relation curve of high and electrode spacing of tube bus. If the tube bus in HVDC converter substation is installed at the high and electrode spacing, got by the relation curve, it will not generate corona and its electric field strength will meet the requirements. The control indexes of tube bus corona characteristic parameters for HVDC converter substation are confirmed in combination with calculation results and related standards. Based on the control indexes, the paper gives the collocations of different tube bus types.

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