Numerical analysis of the operating characteristics of a large‐scale CFB coal‐gasification reactor with the QC‐EMMS drag model

2020 ◽  
Author(s):  
Yang Liu ◽  
Pengju Huo ◽  
Xiaohong Li ◽  
Haiying Qi
Keyword(s):  
Numerical Analysis ◽  
Large Scale ◽  
Coal Gasification ◽  
Operating Characteristics ◽  
Drag Model

scholarly journals Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Jinman Kim ◽  
Heuisoo Han ◽  
Yoonhwa Jin
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Seepage Velocity ◽  
Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

scholarly journals Drawing Reproducible Conclusions from Observational Clinical Data with OHDSI

2021 ◽  
Author(s):  
George Hripcsak ◽  
Martijn J. Schuemie ◽  
David Madigan ◽  
Patrick B. Ryan ◽  
Marc A. Suchard
Keyword(s):  
Large Scale ◽  
Open Science ◽  
Positive Control ◽  
Research Literature ◽  
Observational Research ◽  
Common Data Model ◽  
Administrative Claims ◽  
Open Approach ◽  
Operating Characteristics ◽  
Software Models

Summary Objective: The current observational research literature shows extensive publication bias and contradiction. The Observational Health Data Sciences and Informatics (OHDSI) initiative seeks to improve research reproducibility through open science. Methods: OHDSI has created an international federated data source of electronic health records and administrative claims that covers nearly 10% of the world’s population. Using a common data model with a practical schema and extensive vocabulary mappings, data from around the world follow the identical format. OHDSI’s research methods emphasize reproducibility, with a large-scale approach to addressing confounding using propensity score adjustment with extensive diagnostics; negative and positive control hypotheses to test for residual systematic error; a variety of data sources to assess consistency and generalizability; a completely open approach including protocol, software, models, parameters, and raw results so that studies can be externally verified; and the study of many hypotheses in parallel so that the operating characteristics of the methods can be assessed. Results: OHDSI has already produced findings in areas like hypertension treatment that are being incorporated into practice, and it has produced rigorous studies of COVID-19 that have aided government agencies in their treatment decisions, that have characterized the disease extensively, that have estimated the comparative effects of treatments, and that the predict likelihood of advancing to serious complications. Conclusions: OHDSI practices open science and incorporates a series of methods to address reproducibility. It has produced important results in several areas, including hypertension therapy and COVID-19 research.

Simulation of Flow Field on a Large Scale Wind Turbine

2008 ◽  
Author(s):  
I. Janajreh ◽  
C. Ghenai
Keyword(s):  
Flow Field ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cross Sections ◽  
Large Scale ◽  
Wind Farms ◽  
Operating Characteristics ◽  
Cross Sectional ◽  
Capital Costs

Large scale wind turbines and wind farms continue to evolve mounting 94.1GW of the electrical grid capacity in 2007 and expected to reach 160.0GW in 2010 according to World Wind Energy Association. They commence to play a vital role in the quest for renewable and sustainable energy. They are impressive structures of human responsiveness to, and awareness of, the depleting fossil fuel resources. Early generation wind turbines (windmills) were used as kinetic energy transformers and today generate 1/5 of the Denmark’s electricity and planned to double the current German grid capacity by reaching 12.5% by year 2010. Wind energy is plentiful (72 TW is estimated to be commercially viable) and clean while their intensive capital costs and maintenance fees still bar their widespread deployment in the developing world. Additionally, there are technological challenges in the rotor operating characteristics, fatigue load, and noise in meeting reliability and safety standards. Newer inventions, e.g., downstream wind turbines and flapping rotor blades, are sought to absorb a larger portion of the cost attributable to unrestrained lower cost yaw mechanisms, reduction in the moving parts, and noise reduction thereby reducing maintenance. In this work, numerical analysis of the downstream wind turbine blade is conducted. In particular, the interaction between the tower and the rotor passage is investigated. Circular cross sectional tower and aerofoil shapes are considered in a staggered configuration and under cross-stream motion. The resulting blade static pressure and aerodynamic forces are investigated at different incident wind angles and wind speeds. Comparison of the flow field results against the conventional upstream wind turbine is also conducted. The wind flow is considered to be transient, incompressible, viscous Navier-Stokes and turbulent. The k-ε model is utilized as the turbulence closure. The passage of the rotor blade is governed by ALE and is represented numerically as a sliding mesh against the upstream fixed tower domain. Both the blade and tower cross sections are padded with a boundary layer mesh to accurately capture the viscous forces while several levels of refinement were implemented throughout the domain to assess and avoid the mesh dependence.

Field test of large-scale hydrogen manufacturing from underground coal gasification (UCG)

2008 ◽  
Vol 33 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
Lanhe Yang ◽  
Xing Zhang ◽  
Shuqin Liu ◽  
Li Yu ◽  
Weilian Zhang
Keyword(s):  
Field Test ◽  
Large Scale ◽  
Coal Gasification ◽  
Underground Coal Gasification

scholarly journals System Status of the Water-Cooled Gas Turbine for the High Temperature Turbine Technology Program

1979 ◽  
Author(s):  
A. Caruvana ◽  
W. H. Day ◽  
G. A. Cincotta ◽  
R. S. Rose
Keyword(s):  
Gas Turbine ◽  
Coal Gasification ◽  
Combined Cycle ◽  
Operating Characteristics ◽  
General Electric Company ◽  
Technology Program ◽  
Coal Gas ◽  
Electric Company ◽  
Commercial Viability ◽  
The Status

This paper presents an update on the status of the technology of the water-cooled gas turbine developed by the General Electric Company under contracts with EPRI, ERDA, and DOE. Particular emphasis is devoted to the design and development of water-cooled composite turbine nozzles and buckets, and a sectoral combustor designed for low-Btu coal-derived gas operation. The operating characteristics of a low-temperature coal gas chemical cleanup system which is to be added to the coal gasification facility are also discussed. Status of the materials and process developments in support of the designs are also presented, as are updates to the Phase I HTTT Program combined-cycle studies, which evaluate the commercial viability of integrated coal gasification and combined-cycle operation.

scholarly journals Low and very low birth weight in puppies: definitions, risk factors and survival in a large-scale population

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Amélie Mugnier ◽  
Sylvie Chastant-Maillard ◽  
Hanna Mila ◽  
Faouzi Lyazrhi ◽  
Florine Guiraud ◽  
...  
Keyword(s):  
Risk Factors ◽  
Birth Weight ◽  
Low Birth Weight ◽  
Neonatal Mortality ◽  
Litter Size ◽  
Large Scale ◽  
Very Low Birth Weight ◽  
Regression Tree ◽  
Classification And Regression Tree ◽  
Operating Characteristics

Abstract Background Neonatal mortality (over the first three weeks of life) is a major concern in canine breeding facilities as an economic and welfare issue. Since low birth weight (LBW) dramatically increases the risk of neonatal death, the risk factors of occurrence need to be identified together with the chances and determinants of survival of newborns at-risk. Results Data from 4971 puppies from 10 breeds were analysed. Two birth weight thresholds regarding the risk of neonatal mortality were identified by breed, using respectively Receiver Operating Characteristics and Classification and Regression Tree method. Puppies were qualified as LBW and very low birth weight (VLBW) when their birth weight value was respectively between the two thresholds and lower than the two thresholds. Mortality rates were 4.2, 8.8 and 55.3%, in the normal, LBW and VLBW groups, accounting for 48.7, 47.9 and 3.4% of the included puppies, respectively. A separate binary logistic regression approach allowed to identify breed, gender and litter size as determinants of LBW. The increase in litter size and being a female were associated with a higher risk for LBW. Survival for LBW puppies was reduced in litters with at least one stillborn, compared to litters with no stillborn, and was also reduced when the dam was more than 6 years old. Concerning VLBW puppies, occurrence and survival were influenced by litter size. Surprisingly, the decrease in litter size was a risk factor for VLBW and also reduced their survival. The results of this study suggest that VLBW and LBW puppies are two distinct populations. Moreover, it indicates that events and factors affecting intrauterine growth (leading to birth weight reduction) also affect their ability to adapt to extrauterine life. Conclusion These findings could help veterinarians and breeders to improve the management of their facility and more specifically of LBW puppies. Possible recommendations would be to only select for reproduction dams of optimal age and to pay particular attention to LBW puppies born in small litters. Further studies are required to understand the origin of LBW in dogs.

A material-property-dependent sub-grid drag model for coarse-grained simulation of 3D large-scale CFB risers

2019 ◽  
Vol 204 ◽  
pp. 228-245 ◽  
Author(s):  
Li-Tao Zhu ◽  
Yuan-Xing Liu ◽  
Jia-Xun Tang ◽  
Zheng-Hong Luo
Keyword(s):  
Material Property ◽  
Large Scale ◽  
Coarse Grained ◽  
Drag Model

Numerical analysis of working fluids for large scale centrifugal compressor driven cascade heat pumps upgrading waste heat

2020 ◽  
Vol 269 ◽  
pp. 115056 ◽  
Author(s):  
Antti Uusitalo ◽  
Teemu Turunen-Saaresti ◽  
Juha Honkatukia ◽  
Jonna Tiainen ◽  
Ahti Jaatinen-Värri
Keyword(s):  
Numerical Analysis ◽  
Centrifugal Compressor ◽  
Large Scale ◽  
Waste Heat ◽  
Heat Pumps ◽  
Working Fluids

scholarly journals Visual epidural field potentials possess high functional specificity in single trials

2019 ◽  
Vol 122 (4) ◽  
pp. 1634-1648 ◽  
Author(s):  
Benjamin Fischer ◽  
Andreas Schander ◽  
Andreas K. Kreiter ◽  
Walter Lang ◽  
Detlef Wegener
Keyword(s):  
Visual Cortex ◽  
Minimally Invasive ◽  
Primary Visual Cortex ◽  
Neuronal Activity ◽  
Large Scale ◽  
Field Potentials ◽  
Operating Characteristics ◽  
Invasive Approach ◽  
Spatial Selectivity ◽  
Minimal Invasiveness

Recordings of epidural field potentials (EFPs) allow neuronal activity to be acquired over a large region of cortical tissue with minimal invasiveness. Because electrodes are placed on top of the dura and do not enter the neuronal tissue, EFPs offer intriguing options for both clinical and basic science research. On the other hand, EFPs represent the integrated activity of larger neuronal populations and possess a higher trial-by-trial variability and a reduced signal-to-noise ratio due the additional barrier of the dura. It is thus unclear whether and to what extent EFPs have sufficient spatial selectivity to allow for conclusions about the underlying functional cortical architecture, and whether single EFP trials provide enough information on the short timescales relevant for many clinical and basic neuroscience purposes. We used the high spatial resolution of primary visual cortex to address these issues and investigated the extent to which very short EFP traces allow reliable decoding of spatial information. We briefly presented different visual objects at one of nine closely adjacent locations and recorded neuronal activity with a high-density epidural multielectrode array in three macaque monkeys. With the use of receiver operating characteristics (ROC) to identify the most informative data, machine-learning algorithms provided close-to-perfect classification rates for all 27 stimulus conditions. A binary classifier applying a simple max function on ROC-selected data further showed that single trials might be classified with 100% performance even without advanced offline classifiers. Thus, although highly variable, EFPs constitute an extremely valuable source of information and offer new perspectives for minimally invasive recording of large-scale networks. NEW & NOTEWORTHY Epidural field potential (EFP) recordings provide a minimally invasive approach to investigate large-scale neural networks, but little is known about whether they possess the required specificity for basic and clinical neuroscience. By making use of the spatial selectivity of primary visual cortex, we show that single-trial information can be decoded with close-to-perfect performance, even without using advanced classifiers and based on very few data. This labels EFPs as a highly attractive and widely usable signal.

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