A Practical Algorithm for Calculating the Impulse Earthing Resistances of Vertical Earthing Electrodes

2021 ◽  
Vol 1 (2) ◽  
pp. 15-20
Author(s):  
Yongzheng Zhang ◽  
◽  
Xiaoqing Zhang ◽  
Keyword(s):  
Current Density ◽  
Potential Method ◽  
Effective Radius ◽  
Nonlinear Characteristic ◽  
Ionization Zone ◽  
Average Potential ◽  
Previous Algorithm ◽  
Practical Algorithm ◽  
Soil Ionization ◽  
The Relationship

An algorithm is proposed in this paper for calculating the impulse earthing resistances of vertical earthing electrodes. The proposed algorithm employs the average potential method to derive the formula of the low current earthing resistance. Unlike the previous algorithm, the soil ionization effect under high impulse current is taken into account by introducing a nonlinear characteristic to represent the relationship between the electric field and current density in the ionization zone around the earthing electrode. On the basis of the nonlinear characteristic, the effective radius is evaluated for the equivalent earthing electrode. Then, the impulse earthing resistance can be calculated by substituting the effective radius into the formula of the low current earthing resistance. A comparison is also made between calculated and measured results to confirm the validity of the proposed algorithm. Keywords: Earthing Resistance; Vertical Earthing Electrode; Average Potential Integral; Soil Ionization; Current Density;

Investigation of the Water Guided Laser Micro-Jet Machining of Aero Engine Components

2017 ◽  
Author(s):  
Zhigang Wang
Keyword(s):  
Energy Density ◽  
Material Removal ◽  
Removal Rate ◽  
Cutting Speed ◽  
Potential Method ◽  
Laser Machining ◽  
Aero Engine ◽  
Engine Components ◽  
The Relationship ◽  
Dual Laser

The water guided laser micro-jet (LMJ) is a new potential method to machine aero engine parts with much less heat affected area and faster cutting speed than dry laser machining. The focus of this paper is to investigate the energy density and material removal for a dual-laser LMJ system. Then, the effects of dominated parameters on the energy density of LMJ are analyzed. Finally, a mathematical model is developed to describe the relationship between dominant laser parameters with the energy density of LMJ and material removal rate followed by machining case studies of aero engine components.

scholarly journals Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Zhonglu Cao ◽  
Makoto Hibino ◽  
Hiroki Goda
Keyword(s):  
Corrosion Behavior ◽  
Current Density ◽  
Polarization Resistance ◽  
Cement Mortar ◽  
Corrosion Current ◽  
Potential Difference ◽  
Reinforcing Steel ◽  
Macrocell Current ◽  
The Relationship ◽  
Macrocell Corrosion

The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

Information Content of AVHRR Channels 4 and 5 with Respect to the Effective Radius of Cirrus Cloud Particles

1991 ◽  
Vol 30 (7) ◽  
pp. 973-984 ◽  
Author(s):  
F. Parol ◽  
J. C. Buriez ◽  
G. Brogniez ◽  
Y. Fouquart
Keyword(s):  
Absorption Coefficient ◽  
Mean Value ◽  
Effective Radius ◽  
Forward Peak ◽  
Effective Absorption Coefficient ◽  
Brightness Temperatures ◽  
Microphysical Properties ◽  
Effective Absorption ◽  
Cloud Particles ◽  
The Relationship

Abstract This paper investigates the important difference in the relationship between brightness temperatures between the 11-μm and the 12-μn AVHRR data and the microphysical properties of the semitransparent cirrus clouds. In the nonscattering approximation, the emittance for channels 4 and 5 are related through the absorption coefficient ratio that is the key parameter giving access to the size of cloud particles. The observed mean value of this parameter corresponds to effective radius of 18 μm for polydisperse spheres and 12 μm for polydisperse infinitely long ice cylinders. Taking the multiple scattering into account, the brightness temperature difference enhances much more for cylinders than for spheres owing to the fact that the forward peak of scattering is less large for cylinders. To obtain the size of cloud particles, the method developed in the nonscattering case is still applicable if one makes use of the effective emittance that implicitly includes the effects of mattering. Thus, an effective absorption coefficient ratio is defined and we derive a direct relationship between this ratio and the optical properties of the cloud particles. The mean value of the effective absorption coefficient ratio corresponds to ice spheres of effective radius of 26 μm or a bit less in the case of water spheres (supercooled droplets), but no agreement can be obtained for fully randomly oriented cylinders.

Study on Electronic Structure of GaN under Pressure

2014 ◽  
Vol 900 ◽  
pp. 217-221
Author(s):  
Xing Xiang Ruan ◽  
Xian Hui Zhong ◽  
Fu Chun Zhang ◽  
Wei Hu Zhang
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Potential Method ◽  
High Energy ◽  
Functional Theory ◽  
Conduction Bands ◽  
The Density Functional Theory ◽  
The Relationship ◽  
Pseudo Potential

A detailed theoretical study of electronic structure and optical properties of GaN under pressure was performed by the first-principles calculations of plane wave ultra-soft pseudo-potential method based on the density functional theory (DFT). The results indicate that Ga-N bond length becomes shorter and the valence bonds shift towards the low energy while the conduction bands towards high energy, the band gap becomes wider with the pressure increasing, and theoretical studies explained the relationship between the band edges, energy gap of GaN and pressure. In addition, the peak in band was cracked slightly, and the Ga 3d-N 2p hybridization was enhanced.

scholarly journals On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models

2009 ◽  
Vol 9 (22) ◽  
pp. 8889-8901 ◽  
Author(s):  
A. W. Merkel ◽  
D. R. Marsh ◽  
A. Gettelman ◽  
E. J. Jensen
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Computational Cost ◽  
Cloud Microphysics ◽  
Effective Radius ◽  
Local Temperature ◽  
Decadal Scale ◽  
Ice Water Content ◽  
Ice Water ◽  
The Relationship

Abstract. The distribution of ice layers in the polar summer mesosphere (called polar mesospheric clouds or PMCs) is sensitive to background atmospheric conditions and therefore affected by global-scale dynamics. To investigate this coupling it is necessary to simulate the global distribution of PMCs within a 3-dimensional (3-D) model that couples large-scale dynamics with cloud microphysics. However, modeling PMC microphysics within 3-D global chemistry climate models (GCCM) is a challenge due to the high computational cost associated with particle following (Lagrangian) or sectional microphysical calculations. By characterizing the relationship between the PMC effective radius, ice water content (iwc), and local temperature (T) from an ensemble of simulations from the sectional microphysical model, the Community Aerosol and Radiation Model for Atmospheres (CARMA), we determined that these variables can be described by a robust empirical formula. The characterized relationship allows an estimate of an altitude distribution of PMC effective radius in terms of local temperature and iwc. For our purposes we use this formula to predict an effective radius as part of a bulk parameterization of PMC microphysics in a 3-D GCCM to simulate growth, sublimation and sedimentation of ice particles without keeping track of the time history of each ice particle size or particle size bin. This allows cost effective decadal scale PMC simulations in a 3-D GCCM to be performed. This approach produces realistic PMC simulations including estimates of the optical properties of PMCs. We validate the relationship with PMC data from the Solar Occultation for Ice Experiment (SOFIE).

scholarly journals The relationship between depletion of intracellular Ca2+ stores and activation of Ca2+ current by muscarinic receptors in neuroblastoma cells.

1995 ◽  
Vol 106 (5) ◽  
pp. 975-993 ◽  
Author(s):  
C Mathes ◽  
S H Thompson
Keyword(s):  
Muscarinic Receptors ◽  
Current Density ◽  
Time Course ◽  
Neuroblastoma Cells ◽  
Calcium Stores ◽  
Store Depletion ◽  
Selective Membrane ◽  
Current Activation ◽  
M1 Muscarinic ◽  
The Relationship

The relationship between the depletion of IP3-releasable intracellular Ca2+ stores and the activation of Ca(2+)-selective membrane current was determined during the stimulation of M1 muscarinic receptors in N1E-115 neuroblastoma cells. External Ca2+ is required for refilling Ca2+ stores and the voltage-independent, receptor-regulated Ca2+ current represents a significant Ca2+ source for refilling. The time course of Ca2+ store depletion was measured with fura-2 fluorescence imaging, and it was compared with the time course of Ca2+ current activation measured with nystatin patch voltage clamp. At the time of maximum current density (0.18 + .03 pA/pF; n = 48), the Ca2+ content of the IP3-releasable Ca2+ pool is reduced to 39 + 3% (n = 10) of its resting value. Calcium stores deplete rapidly, reaching a minimum Ca2+ content in 15-30 s. The activation of Ca2+ current is delayed by 10-15 s after the beginning of Ca2+ release and continues to gradually increase for nearly 60 s, long after Ca2+ release has peaked and subsided. The delay in the appearance of the current is consistent with the idea that the production and accumulation of a second messenger is the rate-limiting step in current activation. The time course of Ca2+ store depletion was also measured after adding thapsigargin to block intracellular Ca2+ ATPase. After 15 min in thapsigargin, IP3-releasable Ca2+ stores are depleted by > 90% and the Ca2+ current is maximal (0.19 + 0.05 pA/pF; n = 6). Intracellular loading with the Ca2+ buffer EGTA/AM (10 microM; 30 min) depletes IP3-releasable Ca2+ stores by between 25 and 50%, and it activates a voltage-independent inward current with properties similar to the current activated by agonist or thapsigargin. The current density after EGTA/AM loading (0.61 + 0.32 pA/pF; n = 4) is three times greater than the current density in response to agonist or thapsigargin. This could result from partial removal of Ca(2+)-dependent inactivation.

Effects of Cathode-Mandrel Surface Irregularities on the Mechanical Properties and Structure of Electroformed Iron Foil

1980 ◽  
Vol 22 (2) ◽  
pp. 49-54 ◽  
Author(s):  
W. A. Crichton ◽  
J. A. McGeough ◽  
J. R. Thomson
Keyword(s):  
Surface Roughness ◽  
Current Density ◽  
Cathode Surface ◽  
Foil Thickness ◽  
Iron Foil ◽  
Surface Irregularities ◽  
The Face ◽  
The Relationship ◽  
A Current ◽  
Cathodic Surface

Iron foil, of thicknesses between 003 and 0.15 mm has been electroformed at a current density of 30 A/dm2 and an electrolyte temperature of 100°C upon cathodes of surface roughness ranging from 0.04 to 4.4 μm Ra. The surface roughnesses of the face of the foil formed adjacent to the cathode, and of that electrode, are similar. The roughness of the reverse anodic face increases with increasing foil thickness, due to the increase in size of the crystal growth sites. The hardness of the cathodic face of the foil is unaffected by either cathode surface roughness or foil thickness. The hardness of the anodic face increases with both increasing cathode surface roughness and decreasing foil thickness, due to corresponding changes in grain size. A slight net decrease in tensile properties with increasing cathode surface roughness is attributed to the greater amount of stress concentration borne by the rougher foils. Young's modulus for the foil is not affected by cathode surface roughness. The electroforming of foil upon a mandrel surface carrying an isolated V-shaped scratch, 0.14 mm deep and 0.28 mm wide, has also been studied by numerical and experimental methods. The cathodic surface of foil is found to adopt the shape of the scratch whilst its upper side becomes level. The effect upon the geometric configuration of the foil depends upon the relationship between current efficiency and current density for the electrolyte, and on the polarisation (overpotential) characteristics at the mandrel surface.

Sign in / Sign up

Export Citation Format

Share Document