Performances of hydrophobic cycloaliphatic epoxies exposed to acidic fog under DC stress

2014 ◽  
Author(s):  
Hongjie Sun ◽  
Yibo Zhang ◽  
Hoan D. Le ◽  
Fumei Wu ◽  
Jiansheng Chen ◽  
...  
Keyword(s):  
Acidic Fog ◽  
Dc Stress

Growth properties of sulfide trees in cables under dc stress

1997 ◽  
Vol 4 (6) ◽  
pp. 800-805 ◽  
Author(s):  
P. Anelli ◽  
A. Motori ◽  
I. Ghinello ◽  
G. Mazzanti ◽  
G.C. Montanari
Keyword(s):  
Growth Properties ◽  
Dc Stress

The Effects of Sequential Exposure to Acidic Fog and Ozone on Pulmonary Function in Exercising Subjects

1991 ◽  
Vol 143 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Robert Aris ◽  
Dorothy Christian ◽  
Dean Sheppard ◽  
John R. Balmes
Keyword(s):  
Pulmonary Function ◽  
Acidic Fog

Determination of AlGaN/GaN HEMT Reliability Using Optical Pumping as a Characterization Method

2012 ◽  
Vol 1432 ◽  
Author(s):  
D. Cheney ◽  
R. Deist ◽  
B. Gila ◽  
F. Ren ◽  
P. Whiting ◽  
...  
Keyword(s):  
Band Gap ◽  
Optical Pumping ◽  
Drain Current ◽  
Stress Tests ◽  
Optically Pumped ◽  
Gan Hemt ◽  
Load Line ◽  
Gan Hemts ◽  
Dc Stress

ABSTRACTBy pumping AlGaN/GaN HEMTs with below band-gap light we observe changes in drain current that correspond to the trapping and detrapping of carriers within the band-gap. These changes in drain current are indicators of trap density, since the energy from a specific wavelength of light pumps traps whose activation energies are less than or equal to that of the light source.AlGaN/GaN HEMTs on SiC with dual submicron gates with widths of 125nm, 140nm, or 170nm, are DC-stressed under three different conditions along a load line: VGS=0, VDS=5 (on-state), VGS=-2, VDS=9.2 and, VGS=-6, VDS=25 (off-state). The stress tests are interrupted at 20% degradation and the optically pumped comparisons to the baseline are measured.This paper describes the optical pumping technique and results from experiments of AlGaN/GaN HEMTs under the three DC stress biases along a load line.

Birch foliar responses to simulated acidic fog and Septoria betulae inoculations

2001 ◽  
Vol 31 (3) ◽  
pp. 392-400
Author(s):  
K B Kouterick ◽  
J M Skelly ◽  
S P Pennypacker ◽  
R M Cox
Keyword(s):  
Bay Of Fundy ◽  
Betula Papyrifera ◽  
Mature Trees ◽  
The Past ◽  
Foliar Symptoms ◽  
Foliar Symptom ◽  
Foliar Senescence ◽  
Symptomatic Leaf ◽  
Acidic Fog ◽  
Ph Level

The effects of simulated acidic fog and inoculation with Septoria betulae Pass. on foliar symptom development and foliar senescence of Betula papyrifera Marsh. and Betula cordifolia Regel seedlings were investigated in 1997 and 1998 under greenhouse conditions. An interactive role may exist between acidic fog events and S. betulae in causing birch foliar browning, a disease reported over the past decade to occur on mature trees growing adjacent to the Bay of Fundy, Canada. Seedlings received applications of simulated fog adjusted to pH 3.2, 4.2, and 5.6 or a no-fog treatment. Inoculation treatments at each fog pH level were accomplished through spray atomization with S. betulae conidial suspensions and by placing naturally infected birch leaves bearing pycnidia of the fungus on plastic nets suspended above seedlings in enclosed chambers. Percent symptomatic leaf area of seedlings inoculated with S. betulae was nearly double that recorded for non-inoculated seedlings. Foliar browning resembled symptoms observed on mature trees in the field. Foliar symptoms were observed on non-inoculated seedlings, with greater severities associated with seedlings exposed to the most acidic fog treatment. Leaf senescence was also greatest for spray-inoculated leaves that had been exposed to the pH 3.2 fog treatment. Pycnidial development was not influenced by the pH of the fog treatments but was greater in all fog treatments than in no-fog treatments. Although both acidic fog and S. betulae infection are able to cause symptoms independently, the data suggest that an interactive role may exist in causing birch foliar browning. However, to obtain the same severity of foliar browning as observed on natural forest-grown trees in the Bay of Fundy region, S. betulae must be present.

A self-assembled, nacre-mimetic, nano-laminar structure as a superior charge dissipation coating on insulators for HVDC gas-insulated systems

Nanoscale ◽  
2019 ◽  
Vol 11 (39) ◽  
pp. 18046-18051 ◽  
Author(s):  
Boya Zhang ◽  
Qiang Wang ◽  
Yunxiao Zhang ◽  
Wenqiang Gao ◽  
Yicen Hou ◽  
...  
Keyword(s):  
Surface Charge ◽  
High Voltage ◽  
Layered Structure ◽  
Laminar Structure ◽  
Self Assembled ◽  
Dc Stress

By mimicking the layered structure of nacre, we successfully fabricated a nano-laminar coating on high-voltage insulators. The coating is demonstrated to achieve a higher flashover strength by effectively dissipating surface charge under dc stress.

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.

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