scholarly journals Evolution Characteristics during Initial Stage of Triggered Lightning Based on Directly Measured Current

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 658
Author(s):  
Zefang Chen ◽  
Yang Zhang ◽  
Yanfeng Fan ◽  
Jingxuan Wang ◽  
Dong Zheng ◽  
...  
Keyword(s):  
Lightning Discharge ◽  
Ground Level ◽  
Current Data ◽  
Discharge Process ◽  
Measured Current ◽  
Critical Range ◽  
Initial Stage ◽  
Evolution Characteristics ◽  
Triggered Lightning ◽  
Initial Process

The initiation of a leader is an important lightning discharge process, but how an upward positive leader (UPL) initiates is still not fully understood. The evolution characteristics of a UPL during its initial stage was systematically studied based on directly measured current data of 14 triggered lightning events in 2019. It was found that the initial stage of triggered lightning can be divided into two types: a single initial process form and a multiple initial process form, with percentages of 64.29% and 35.71%, respectively. Compared with the former, the latter usually lasts longer, and the corresponding lightning is often triggered under a lower ground-level quasi-static electric field. In each initial process, precursor current pulses (PCPs), PCP clusters and initial precursor current pulse (IPCPs) are typical current waveforms, and the pulse durations and transferred charges of PCPs increase linearly with time. However, in the multiple initial process form, the pulse durations and transferred charges of PCPs will reduce significantly after each previous initial process and then continue to increase in the following initial process. In each initial process, when the pulse duration and transferred charge of a PCP increase to a certain extent, PCP clusters and IPCPs begin to appear. For the emergence of PCP clusters, the average values of the threshold are 3.48 μs and 19.53 μC, respectively. For the occurrence of IPCPs, the corresponding values are 4.69 μs and 27.23 μC, respectively. The average values of pulse durations and transferred charges of IPCPs are larger than those of PCP clusters. Compared with adjacent PCP clusters, IPCPs contain more pulses, with a critical range of 6–7. IPCPs also last longer, and have a critical range of 138–198 μs.

scholarly journals Fast and Fine Location of Total Lightning from Low Frequency Signals Based on Deep-Learning Encoding Features

2021 ◽  
Vol 13 (11) ◽  
pp. 2212
Author(s):  
Jingxuan Wang ◽  
Yang Zhang ◽  
Yadan Tan ◽  
Zefang Chen ◽  
Dong Zheng ◽  
...  
Keyword(s):  
Deep Learning ◽  
Signal To Noise Ratio ◽  
Lightning Discharge ◽  
Low Frequency ◽  
New Method ◽  
Discharge Process ◽  
Matching Efficiency ◽  
Triggered Lightning ◽  
Artificial Intelligence Technology ◽  
Total Lightning

Lightning location provides an important means for the study of lightning discharge process and thunderstorms activity. The fine positioning capability of total lightning based on low-frequency signals has been improved in many aspects, but most of them are based on post waveform processing, and the positioning speed is slow. In this study, artificial intelligence technology is introduced for the first time to lightning positioning, based on low-frequency electric-field detection array (LFEDA). A new method based on deep-learning encoding features matching is also proposed, which provides a means for fast and fine location of total lightning. Compared to other LFEDA positioning methods, the new method greatly improves the matching efficiency, up to more than 50%, thereby considerably improving the positioning speed. Moreover, the new algorithm has greater fine-positioning and anti-interference abilities, and maintains high-quality positioning under low signal-to-noise ratio conditions. The positioning efficiency for return strokes of triggered lightning was 99.17%, and the standard deviation of the positioning accuracy in the X and Y directions was approximately 70 m.

scholarly journals Observations of the initial stage of a rocket-and-wire-triggered lightning discharge

2017 ◽  
Vol 44 (9) ◽  
pp. 4332-4340 ◽  
Author(s):  
Yang Zhang ◽  
Paul R. Krehbiel ◽  
Yijun Zhang ◽  
Weitao Lu ◽  
Dong Zheng ◽  
...  
Keyword(s):  
Lightning Discharge ◽  
Initial Stage ◽  
Triggered Lightning

scholarly journals Characterization of the initial stage of negative rocket-triggered lightning

1999 ◽  
Vol 104 (D4) ◽  
pp. 4213-4222 ◽  
Author(s):  
D. Wang ◽  
V. A. Rakov ◽  
M. A. Uman ◽  
M. I. Fernandez ◽  
K. J. Rambo ◽  
...  
Keyword(s):  
Initial Stage ◽  
Triggered Lightning

scholarly journals Atypical start-up experiments on pump as turbine

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110627
Author(s):  
Yu-Liang Zhang ◽  
Yan-Juan Zhao
Keyword(s):  
Static Pressure ◽  
Power Coefficient ◽  
Transient Performance ◽  
Test Rig ◽  
Transient Characteristics ◽  
Maximum Value ◽  
Start Up ◽  
Initial Stage ◽  
Evolution Characteristics ◽  
The Impact

At present, research on the characteristics of pumps as turbine (PATs) during the start-up process is still insufficient. To reveal the transient characteristics of a centrifugal PAT during the atypical start-up process, a test rig for the transient performance of the PAT was built; in addition, experiments on the transient hydraulic performance of three kinds of steady speed and three kinds of steady flow were conducted. Through these experiments, the evolution characteristics of the transient performance parameters of the PAT during the atypical start-up process were analyzed over time. Moreover, three dimensionless coefficients were employed to deeply reveal the transient characteristics of the PAT during atypical start-up. Results showed that the rise curves of flow rate and outlet static pressure exhibited shock phenomena. With the increase in the stable running speed after start-up, the impact phenomenon of the outlet static pressure presented a delayed trend. The dimensionless head and flow coefficients reached the maximum value at the initial stage of the atypical start-up process and then rapidly dropped to the minimum value before slowly rising to the final stable value. The dimensionless power coefficient had a maximum value at the initial stage of atypical start-up and then rapidly dropped to the final stable value.

Analysis of radiation evolution characteristics of the artificial triggered lightning channel

2019 ◽  
Vol 12 (3) ◽  
pp. 670-677
Author(s):  
张华明 ZHANG Hua-ming ◽  
吕伟涛 L Wei-tao ◽  
张 阳 ZHANG Yang ◽  
张义军 ZHANG Yi-jun ◽  
樊艳峰 FAN Yan-feng ◽  
...  
Keyword(s):  
Lightning Channel ◽  
Evolution Characteristics ◽  
Triggered Lightning

Upward negative leaders in positive triggered lightning: Stepping and branching in the initial stage

2017 ◽  
Vol 44 (13) ◽  
pp. 7029-7035 ◽  
Author(s):  
Yunjiao Pu ◽  
Rubin Jiang ◽  
Xiushu Qie ◽  
Mingyuan Liu ◽  
Hongbo Zhang ◽  
...  
Keyword(s):  
Initial Stage ◽  
Triggered Lightning

High Efficiency Large Area a-Si:H and a-SiGe:H Multi-junction Solar Cells Using MVHF at High Deposition Rate

2009 ◽  
Vol 1153 ◽  
Author(s):  
Xixiang Xu ◽  
Dave Beglau ◽  
Scott Ehlert ◽  
Yang Li ◽  
Tining Su ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
High Deposition Rate ◽  
Discharge Process ◽  
Large Area ◽  
Very High Frequency ◽  
Cell Structures ◽  
Evolution Characteristics ◽  
Stable Performance ◽  
Sun Light

AbstractWe have developed high efficiency large area a-Si:H and a-SiGe:H multi-junction solar cells using a Modified Very High Frequency (MVHF) glow discharge process. We conducted a comparative study for different cell structures, and compared the initial and stable performance and light-induced degradation of solar cells made using MVHF and RF techniques. Besides high efficiency, the MVHF cells also demonstrate superior light stability, showing <10% degradation after 1000 hour of one-sun light soaking at 50 °C. We also studied light-induced defect level and hydrogen evolution characteristics of MVHF deposited a-SiGe:H films and compared them with the RF deposited films.

scholarly journals A ground level gamma-ray burst observed in association with rocket-triggered lightning

2004 ◽  
Vol 31 (5) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. R. Dwyer ◽  
H. K. Rassoul ◽  
M. Al-Dayeh ◽  
L. Caraway ◽  
B. Wright ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ground Level ◽  
Gamma Ray Burst ◽  
Triggered Lightning

scholarly journals Heat Based Power Augmentation for Modular Pumped Hydro Storage in Smart Buildings Operation

2021 ◽  
Author(s):  
Yang Chen ◽  
Ahmad Abu-Heiba ◽  
Saiid Kassaee ◽  
Chenang Liu ◽  
Guodong Liu ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Ground Level ◽  
Small Scale ◽  
Low Grade ◽  
Discharge Process ◽  
Gas Temperature ◽  
Oak Ridge ◽  
Storage Technology ◽  
Low Grade Heat

Abstract In the U.S., building sector is responsible for around 40% of total energy consumption and contributes about 40% of carbon emissions since 2012. Within the past several years, various optimization models and control strategies have been studied to improve buildings energy efficiency and reduce operational expenses under the constraints of satisfying occupants’ comfort requirements. However, the majority of these studies consider building electricity demand and thermal load being satisfied by unidirectional electricity flow from the power grid or on-site renewable energy generation to electrical and thermal home appliances. Opportunities for leveraging low grade heat for electricity have largely been overlooked due to impracticality at small scale. In 2016, a modular pumped hydro storage technology was invented in Oak Ridge National Laboratory, named Ground Level Integrated Diverse Energy Storage (GLIDES). In GLIDES, employing high efficiency hydraulic machinery instead of gas compressor/turbine, liquid is pumped to compress gas inside high-pressure vessel creating head on ground-level. This unique design eliminates the geographical limitation associated with existing state of the art energy storage technologies. It is easy to be scaled for building level, community level and grid level applications. Using this novel hydro-pneumatic storage technology, opportunities for leveraging low-grade heat in building can be economical. In this research, the potential of utilizing low-grade thermal energy to augment electricity generation of GLIDES is investigated. Since GLIDES relies on gas expansion in the discharge process and the gas temperature drops during this non-isothermal process, available thermal energy, e.g. from thermal storage, Combined Cooling, Heat and Power system (CCHP), can be utilized by GLIDES to counter the cooling effect of the expansion process and elevate the gas temperature and pressure and boost the roundtrip efficiency. Several groups of comparison experiments have been conducted and the experimental results show that a maximum 12.9% cost saving could be achieved with unlimited heat source for GLIDES, and a moderate 3.8% cost improvement can be expected when operated coordinately with CCHP and thermal energy storage in a smart building.

scholarly journals Lightning for Energy and Material Uses: A Structured Review

2020 ◽  
Author(s):  
Daniel S. Helman
Keyword(s):  
Lightning Discharge ◽  
Atmospheric Electricity ◽  
Dusty Plasmas ◽  
Biomass Energy ◽  
Separation Processes ◽  
New Class ◽  
Surface Charging ◽  
Oceanic Surface ◽  
Triggered Lightning ◽  
Early Translation

The average atmospheric charge density of Earth is neutral. Charge built up from thunderstorms and lightning phenomena is offset by oceanic surface charging, and offers a source of energy that has not been harnessed broadly. Unfortunately, the total terrestrial energy of the Earth’s atmospheric electrical system is modest (250–500 MW) compared to industrial requirements: Innovations are likely to offer improvements to societal efficiency rather than broad transformations. Direct capture systems located in places with very high occurrence of lightning discharge can generate ≈1 kWh per year on average. Material processing via triggered lightning is limited to techniques that utilize rapid discharges, e.g., metal and glass preprocessing of materials, waste volume reduction, biomass energy conversion, where current prices make plasma‐arc processes prohibitive. Triggered lightning may be used to assist blasting of mountain rock; or as a high‐voltage input for processes such as nuclear fusion. Passive collection of atmospheric electricity is modest but may be used in urban agriculture to increase biomass production. Thunderstorm charge‐separation processes suggest a new class of electricity generators based on kinetic energy and material collision. Ball lightning suggests additional research in dusty plasmas. These methods are all at proof‐of‐concept or early translation stages.

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