Modified Shielding Jet Model for Twin-Jet Shielding Analysis

1984 ◽  
Vol 106 (3) ◽  
pp. 421-426
Author(s):  
C. H. Gerhold ◽  
J. Gilbride
Keyword(s):  
Cross Section ◽  
Slug Flow ◽  
Noise Source ◽  
Model Development ◽  
Realistic Model ◽  
Measured Data ◽  
Air Jet ◽  
Constant Radius ◽  
Flow Approximation ◽  
Subsonic Jet

An analytical model to estimate the shielding of noise emitted from a point noise source has been developed assuming the shielding jet to be a cylinder of constant radius with uniform flow across the cross section. Comparison to experiment indicated that the model overestimates diffraction of sound around the jet in the far downstream region. The shielding jet model is modified to include widening downstream of the nozzle exit. This not only represents a more realistic model of the jet, but is also expected to improve the shielding estimate downstream. The modified jet model incorporates a Mach number dependent widening rate, a corresponding decrease in flow velocity downstream and an equivalent slug flow evaluation to retain the locally parallel flow approximation of the model development. The shielding analysis with modified jet model is compared to measured data for a subsonic isothermal air jet and a simulated hot subsonic jet. Improvement of the shielding estimate is discussed.

scholarly journals History, Colonialism, and Archival Methods in Socio-Hydrological Scholarship: A Case Study of the Boerasirie Conservancy in British Guiana

World ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 205-215
Author(s):  
Joshua Mullenite
Keyword(s):  
Environmental History ◽  
Cross Section ◽  
Science And Technology Studies ◽  
Model Development ◽  
Human Geography ◽  
Hydrological Models ◽  
British Guiana ◽  
Current Role

In this article, I review a cross-section of research in socio-hydrology from across disciplines in order to better understand the current role of historical-archival analysis in the development of socio-hydrological scholarship. I argue that despite its widespread use in environmental history, science and technology studies, anthropology, and human geography, archival methods are currently underutilized in socio-hydrological scholarship more broadly, particularly in the development of socio-hydrological models. Drawing on archival research conducted in relation to the socio-hydrology of coastal Guyana, I demonstrate the ways in which such scholarship can be readily incorporated into model development.

Unified Model for Gas-Liquid Pipe Flow Via Slug Dynamics: Part 1 — Model Development

2002 ◽  
Author(s):  
Hong-Quan Zhang ◽  
Qian Wang ◽  
Cem Sarica ◽  
James P. Brill
Keyword(s):  
Flow Pattern ◽  
Pipe Flow ◽  
Slug Flow ◽  
Control Volume ◽  
Model Development ◽  
Flow Patterns ◽  
Hydrodynamic Characteristics ◽  
Momentum Exchange ◽  
Two Phase ◽  
Inclination Angles

A unified hydrodynamic model is developed for predictions of flow pattern transitions, pressure gradient, liquid holdup and slug characteristics in gas-liquid pipe flow at different inclination angles from −90 to 90 deg. The model is based on the dynamics of slug flow, which shares transition boundaries with all the other flow patterns. By use of the entire film zone as the control volume, the momentum exchange between the slug body and the film zone is introduced into the momentum equations for slug flow. The equations of slug flow are used not only to calculate the slug characteristics, but also to predict transitions from slug flow to other flow patterns. Significant effort has been made to eliminate discontinuities among the closure relationships through careful selection and generalization. The flow pattern classification is also simplified according to the hydrodynamic characteristics of two-phase flow.

Sensitivity of Slug Flow Mechanistic Models on Slug Length

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Cem Sarica ◽  
Hong-Quan Zhang ◽  
Robert J. Wilkens
Keyword(s):  
Slug Flow ◽  
Gas Flow ◽  
Model Development ◽  
Unified Model ◽  
Mechanistic Models ◽  
Flow Rates ◽  
Fluid Properties ◽  
The Common ◽  
Pipe Geometry ◽  
Probabilistic Nature

Slug flow is one of the common flow patterns in gas and oil production and transportation. One of the closure relationships required by the multiphase flow mechanistic models is slug length correlation. There are several closure relationships proposed in the literature as function of pipe geometry, pipe diameter, and inclination angle, and to a lesser extent to the flow rates and fluid properties. In this paper, we show that most of the frequently used mechanistic models are insensitive to slug length information. The only exception to this is identified as the Zhang et al. (2003, “Unified Model for Gas-Liquid Pipe Flow via Slug Dynamics—Part 1: Model Development,” ASME J. Energy Resour. Technol., 125, pp. 266–272). The unified model shows sensitivity at high gas flow rates, while displaying a negligible sensitivity at low gas flow rates. In conclusion, the slug length closure relationship is not crucial for pressure loss and holdup calculations. It can be speculated that the success of the unit cell slug flow modeling approach could be attributed to insensitivity of the models to slug length considering the highly probabilistic nature of the slug length.

Effect Review of the Strengthening Technique by Use of the External Prestressing

2011 ◽  
Vol 121-126 ◽  
pp. 3258-3262
Author(s):  
Long Sheng Bao ◽  
Dan Yang ◽  
Ling Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cross Section ◽  
Prestressed Concrete ◽  
Measured Data ◽  
The Finite Element Method ◽  
Construction Monitoring ◽  
External Prestressing ◽  
Monitoring Result ◽  
Strengthening Technique

The grand bridge of Fu Feng is prestressed concrete cross-section continuous girder, which is reinforced with external prestressing. Construction monitoring is based on the measured data, and using the finite element method to calculate, it need to analyze the control of the stress and deflection in the construction to ensure to make the construction could be completed on schedule and to reach an ideal type. The field monitoring result indicates that the type of bridge did improve and reach the requirement of design after reinforcement.

scholarly journals The Use of Synthetic IMU Signals in the Training of Deep Learning Models Significantly Improves the Accuracy of Joint Kinematic Predictions

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5876
Author(s):  
Mohsen Sharifi Renani ◽  
Abigail M. Eustace ◽  
Casey A. Myers ◽  
Chadd W. Clary
Keyword(s):  
Root Mean Square ◽  
Model Development ◽  
Synthetic Data ◽  
Model Performance ◽  
Measured Data ◽  
Training Data ◽  
Machine Learning Techniques ◽  
Mean Square ◽  
Joint Mechanics ◽  
Mean Square Errors

Gait analysis based on inertial sensors has become an effective method of quantifying movement mechanics, such as joint kinematics and kinetics. Machine learning techniques are used to reliably predict joint mechanics directly from streams of IMU signals for various activities. These data-driven models require comprehensive and representative training datasets to be generalizable across the movement variability seen in the population at large. Bottlenecks in model development frequently occur due to the lack of sufficient training data and the significant time and resources necessary to acquire these datasets. Reliable methods to generate synthetic biomechanical training data could streamline model development and potentially improve model performance. In this study, we developed a methodology to generate synthetic kinematics and the associated predicted IMU signals using open source musculoskeletal modeling software. These synthetic data were used to train neural networks to predict three degree-of-freedom joint rotations at the hip and knee during gait either in lieu of or along with previously measured experimental gait data. The accuracy of the models’ kinematic predictions was assessed using experimentally measured IMU signals and gait kinematics. Models trained using the synthetic data out-performed models using only the experimental data in five of the six rotational degrees of freedom at the hip and knee. On average, root mean square errors in joint angle predictions were improved by 38% at the hip (synthetic data RMSE: 2.3°, measured data RMSE: 4.5°) and 11% at the knee (synthetic data RMSE: 2.9°, measured data RMSE: 3.3°), when models trained solely on synthetic data were compared to measured data. When models were trained on both measured and synthetic data, root mean square errors were reduced by 54% at the hip (measured + synthetic data RMSE: 1.9°) and 45% at the knee (measured + synthetic data RMSE: 1.7°), compared to measured data alone. These findings enable future model development for different activities of clinical significance without the burden of generating large quantities of gait lab data for model training, streamlining model development, and ultimately improving model performance.

Spontaneous Liquid-Liquid Slug Flow in Microchannels

2006 ◽  
Author(s):  
Joseph E. Hernandez ◽  
Jeffrey S. Allen
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Slug Flow ◽  
Liquid Surface ◽  
The Self ◽  
Viscous Resistance ◽  
Liquid Slug ◽  
Interfacial Tensions ◽  
Liquid Surfaces

Spontaneous liquid-liquid slug (bislug) flow in microchannels has been observed for both circular and square cross sections. Flow is induced via an imbalance in interfacial tensions and curvatures between the two gas-liquid surfaces and the liquid-liquid surface. Bislug flow in square cross-section microchannels is generally much quicker than bislug flow in circular capillaries for a variety of reasons; including the self-wetting nature of the microchannel and the decrease in viscous resistance in the corners.

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