deep pit
Recently Published Documents


TOTAL DOCUMENTS

122
(FIVE YEARS 27)

H-INDEX

11
(FIVE YEARS 3)

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
James C. Gallagher ◽  
Mona A. Ebrish ◽  
Matthew A. Porter ◽  
Alan G. Jacobs ◽  
Brendan P. Gunning ◽  
...  

AbstractTo improve the manufacturing of vertical GaN devices for power electronics applications, the effects of defects in GaN substrates need to be better understood. Many non-destructive techniques including photoluminescence, Raman spectroscopy and optical profilometry, can be used to detect defects in the substrate and epitaxial layers. Raman spectroscopy was used to identify points of high crystal stress and non-uniform conductivity in a substrate, while optical profilometry was used to identify bumps and pits in a substrate which could cause catastrophic device failures. The effect of the defects was studied using vertical P-i-N diodes with a single zone junction termination extention (JTE) edge termination and isolation, which were formed via nitrogen implantation. Diodes were fabricated on and off of sample abnormalities to study their effects. From electrical measurements, it was discovered that the devices could consistently block voltages over 1000 V (near the theoretical value of the epitaxial layer design), and the forward bias behavior could consistently produce on-resistance below 2 mΩ cm2, which is an excellent value considering DC biasing was used and no substrate thinning was performed. It was found that high crystal stress increased the probability of device failure from 6 to 20%, while an inhomogeneous carrier concentration had little effect on reverse bias behavior, and slightly (~ 3%) increased the on-resistance (Ron). Optical profilometry was able to detect regions of high surface roughness, bumps, and pits; in which, the majority of the defects detected were benign. However a large bump in the termination region of the JTE or a deep pit can induce a low voltage catastrophic failure, and increased crystal stress detected by the Raman correlated to the optical profilometry with associated surface topography.


PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0254730
Author(s):  
Fan Yang ◽  
Daniel S. Andersen ◽  
Steven Trabue ◽  
Angela D. Kent ◽  
Laura M. Pepple ◽  
...  

Foam accumulation in swine manure deep-pits has been linked to explosions and flash fires that pose devastating threats to humans and livestock. It is clear that methane accumulation within these pits is the fuel for the fire; it is not understood what microbial drivers cause the accumulation and stabilization of methane. Here, we conducted a 13-month field study to survey the physical, chemical, and biological changes of pit-manure across 46 farms in Iowa. Our results showed that an increased methane production rate was associated with less digestible feed ingredients, suggesting that diet influences the storage pit’s microbiome. Targeted sequencing of the bacterial 16S rRNA and archaeal mcrA genes was used to identify microbial communities’ role and influence. We found that microbial communities in foaming and non-foaming manure were significantly different, and that the bacterial communities of foaming manure were more stable than those of non-foaming manure. Foaming manure methanogen communities were enriched with uncharacterized methanogens whose presence strongly correlated with high methane production rates. We also observed strong correlations between feed ration, manure characteristics, and the relative abundance of specific taxa, suggesting that manure foaming is linked to microbial community assemblage driven by efficient free long-chain fatty acid degradation by hydrogenotrophic methanogenesis.


Zootaxa ◽  
2021 ◽  
Vol 4985 (2) ◽  
Author(s):  
MINGYI TIAN ◽  
SUNBIN HUANG

Ckacus youcha n. gen. & n. sp. is described and illustrated based on a single male discovered in the deep area of Luoshui Dong, a vertical cave in Anlong Xian, southwestern most of Guizhou Province, Southwest China. This new genus seems related to Bathytrechus Uéno, 2005 from Leye Xian, northwestern most Guangxi by its elongate body which is wholly pubescent, the tridentate right mandible and the well-striated elytra with the 1st interval extremely narrowed at apical 1/3, but differs in several important characters. In addition, three individuals of the species Satotrechus rieae Uéno, 2006 were also collected from -340 m to -450 m in the same cave. This species was formerly only known from four caves in Anlong and Ceheng counties.


Author(s):  
Lingkan Ding ◽  
Hongjian Lin ◽  
Brian Hetchler ◽  
Yuchuan Wang ◽  
Wei Wei ◽  
...  

Author(s):  
A. V. Kvashuk ◽  
◽  
T. D. Dautova ◽  

The article considers the methods for calculating the predicted maximum settlement of buildings in the zone of influence of a deep pit in the conditions of St. Petersburg. There have been analyzed the results of calculations of the predicted maximum settlement by the semi-empirical method developed by Professor N. S. Nikiforova with the settlement values obtained in Plaxis 2D software package. The authors present the evaluation of the possibility of applying a semi-empirical method for determining the predicted settlement of the surrounding building development in the engineering and geological conditions of St. Petersburg.


2021 ◽  
Vol 274 ◽  
pp. 03022
Author(s):  
Ilizar Mirsayapov ◽  
Rubis Khasanov ◽  
Danil Safin

Technical solutions for the reconstruction of the building of the Shamovskaya Hospital, an architectural monument built in 1907-1910, are highlighted in Kazan. The reconstruction involves the construction of a 4- storey underground extension to the building. The implementation of the developed architectural solutions revealed a number of problems associated with ensuring the stability of the foundation when developing a deep pit in the immediate (0.5 m) proximity to the building. The authors propose technical solutions to strengthen the foundations of the existing building of the Shamovskaya Hospital, as well as the structure of the retaining wall.


2021 ◽  
Vol 64 (1) ◽  
pp. 31-48
Author(s):  
Erin L. Cortus ◽  
Brian P. Hetchler ◽  
Mindy J. Spiehs ◽  
Warren C Rusche

HighlightsTemperature and air movement in the naturally ventilated barns correlated to ambient conditions.Manure N-P-K values related to solids distribution in the manure storage.Ammonia and combined sulfur concentrations increased with closer proximity to the manure surface.Influences of manure properties, airflow conditions, barn design, and management were evident for gas concentrations.Abstract. There is a lack of data to describe the range of environmental and air quality conditions in beef cattle confinement buildings with deep-pit manure storage. The objective of this article is to describe the environmental conditions, manure nutrient concentrations, and aerial gas concentrations for three deep-pit manure storage finishing beef cattle facilities and varying weather conditions. Measurements were collected from three barns finishing beef cattle with deep pits in Minnesota on three sampling days per barn in summer, fall, and spring weather conditions. The air temperatures throughout the barns closely mirrored the ambient temperature conditions, although significantly lower temperatures were sometimes evident at the manure surface or in the inlet opening. However, the manure and floor surfaces had 2°C and 5°C temperature increases over ambient temperatures. Air speeds through the barn openings were generally 40% of the ambient wind speed; at animal level, the average air speed was 1 to 3 m s-1. Manure nutrient distributions were not consistent between the surface and agitated (whole pit) samples, and this was likely due in part to solids distribution in the storage. Total nitrogen levels ranged from 4.5 to 6.7 g L-1, and ammonium-N was 50% to 65% of total N in agitated whole-pit samples. Phosphate and potassium oxide levels ranged from 2.8 to 4.2 g L-1 and from 3.7 to 4.5 g L-1, respectively. Aerial ammonia and combined sulfur concentrations varied by location within a barn, pen, and season. Ammonia and combined sulfur increased with proximity to the manure surface. Higher ammonia and combined sulfur concentrations at manure level and floor level for one of the three barns may have related to water quality and/or feed composition and resulting manure nutrients, in addition to warmer temperatures. At floor level, the greatest average ammonia concentration was 8.5 ppm, and 3.9 ppm at nose level. Maximum combined sulfur levels were a maximum of 270 ppb at floor level in summer conditions in one of the barns, while 52 ppb was the maximum average during spring conditions. Carbon dioxide levels also varied by location within a barn, pen, and season and were related in part to the presence of cattle in the pen. This project is the first to quantify air quality in slatted-floor cattle barns and contributes to a body of knowledge that can be used to develop process-based models for estimating air emissions from cattle facilities. Keywords: Airflow, Ammonia, Beef cattle, Confinement, Hydrogenslfide, Manure characteristics, Temperature.


Sign in / Sign up

Export Citation Format

Share Document