On the Use of Bulk Aerodynamic Formulae Over Melting Snow

1983 ◽  
Vol 14 (4) ◽  
pp. 193-206 ◽  
Author(s):  
R. Daniel Moore
Keyword(s):  
Complex Terrain ◽  
Roughness Length ◽  
Melting Snow ◽  
Linear Profiles ◽  
Temperature And Humidity ◽  
The Stability ◽  
Log Linear ◽  
Theoretical Analyses ◽  
Neutral Case ◽  
Scale Length

Bulk aerodynamic formulae which relate the turbulent exchanges of sensible and latent heat over melting snow to measurements of windspeed, temperature and humidity at one level can be derived from flux-gradient relationships and assumed log-linear profiles. Recent analyses of local advection over snow and wind flow over complex terrain suggest that the bulk aerodynamic formulae should apply in non-ideal field situations. The assumption that the scaling lengths for temperature and humidity equal the roughness length is problematic, since theoretical analyses indicate they should be much less than the roughness length. However, the effect of scale length inequality on the stability correction tends to compensate for the effect on the neutral-case transfer coefficient. Field experience indicates that the bulk aerodynamic formulae are adequate for use in energy balance estimates of daily or shorter term snowmelt.

Stability and Hopf Bifurcation of Nearest-Neighbor Coupled Neural Networks With Delays

2020 ◽  
Vol 15 (11) ◽  
Author(s):  
Lu Wang ◽  
Min Xiao ◽  
Shuai Zhou ◽  
Yurong Song ◽  
Jinde Cao
Keyword(s):  
Neural Networks ◽  
Hopf Bifurcation ◽  
Nearest Neighbor ◽  
Multiple Delays ◽  
Dimensional System ◽  
Practical Applications ◽  
Coupled Neural Networks ◽  
The Stability ◽  
Related Characteristic ◽  
Theoretical Analyses

Abstract In this paper, a high-dimensional system of nearest-neighbor coupled neural networks with multiple delays is proposed. Nowadays, most present researches about neural networks have studied the connection between adjacent nodes. However, in practical applications, neural networks are extremely complicated. This paper further considers that there are still connection relationships between nonadjacent nodes, which reflect the intrinsic characteristics of neural networks more accurately because of the complexity of its topology. The influences of multiple delays on the local stability and Hopf bifurcation of the system are explored by selecting the sum of delays as bifurcation parameter and discussing the related characteristic equations. It is found that the dynamic behaviors of the system depend on the critical value of bifurcation. In addition, the conditions that ensure the stability of the system and the criteria of Hopf bifurcation are given. Finally, the correctness of the theoretical analyses is verified by numerical simulation.

scholarly journals Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

2019 ◽  
Vol 7 (6) ◽  
pp. 175 ◽  
Author(s):  
Long Yu ◽  
Heyue Zhang ◽  
Jing Li ◽  
Xian Wang
Keyword(s):  
Bending Moment ◽  
Vertical Force ◽  
Leg Length ◽  
Element Analysis ◽  
Centrifuge Tests ◽  
Flat Base ◽  
Key Factor ◽  
The Stability ◽  
Resultant Forces ◽  
Theoretical Analyses

Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the coupled Eulerian–Lagrangian (CEL) method. The effects of footprints’ geometry, reinstallation eccentricity (0.25D–2.0D) and the roughness between spudcan and soil on the profiles of the vertical force, horizontal force and bending moment are discussed. The results show that the friction condition of the soil–footing interface has a significant effect on H profile but much less effect on M profile. The eccentricity ratio is a key factor to evaluate the H and M. The results show that the geometry shape of the footing also has certain effects on the V, H, and M profiles. The flat base footing gives the lowest peak value in H but largest in M, and the performances of the fusiform spudcan footing and the skirted footing are similar. From the view of the resultant forces, the skirted footing shows a certain potential in resisting the damage during reinstallation near existing footprints by comparing with commonly used fusiform spudcan footings. The bending moments on the leg–hull connection section of different leg length at certain offset distances are discussed.

scholarly journals The Knobe Effect From the Perspective of Normative Orders

Studia Humana ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 9-15
Author(s):  
Andrzej Waleszczyński ◽  
Michał Obidziński ◽  
Julia Rejewska
Keyword(s):  
Essential Role ◽  
Empirical Studies ◽  
The Other ◽  
Human Cognition ◽  
Stable Model ◽  
Mutual Relationship ◽  
Knobe Effect ◽  
Moral Normativity ◽  
The Stability ◽  
Theoretical Analyses

Abstract The characteristic asymmetry in the attribution of intentionality in causing side effects, known as the Knobe effect, is considered to be a stable model of human cognition. This article looks at whether the way of thinking and analysing one scenario may affect the other and whether the mutual relationship between the ways in which both scenarios are analysed may affect the stability of the Knobe effect. The theoretical analyses and empirical studies performed are based on a distinction between moral and non-moral normativity possibly affecting the judgments passed in both scenarios. Therefore, an essential role in judgments about the intentionality of causing a side effect could be played by normative competences responsible for distinguishing between normative orders.

The Preliminary Study on Comparison of Velocity Distribution Models Under the Same Roughness Length

2006 ◽  
Author(s):  
Jialing Hao ◽  
Yixin Yan ◽  
Zhiyao Song ◽  
Changnan Wang
Keyword(s):  
Velocity Profile ◽  
Velocity Distribution ◽  
Linear Model ◽  
Tidal Cycle ◽  
Roughness Length ◽  
Distribution Model ◽  
Surface Boundary ◽  
Distribution Models ◽  
Logarithmic Model ◽  
Log Linear

Previous studies pointed out that due to the acceleration or deceleration action of tide current, the flow structure deviates from traditional logarithmic law in estuary, coast or other near shore water. The tidal velocity distribution model was derived and compared with the traditional logarithmic model. It should be pointed out that the velocity data adopted have four layers within one meter above the bed, and the roughness length z0 is different in the two models even in the same velocity profile. Because the fluctuation of roughness length z0 is remarkable when determining by single velocity profile, some studies thought that the variation of roughness length was small between adjacent time when the change of topography was less obviously. Therefore, the measured data is divided into several sections by one day or a tidal cycle to fit the velocity profile of every section to obtain a roughness length z0, i.e., the roughness length z0 varies only after a day or a tidal cycle. The purpose of the paper is to expand the log-linear model to full depth by adding the surface boundary condition ∂u∂zz=D=0(Diswaterdepth) and to discuss the difference when 6 points (bottom layer, 0.2D, 0.4D, 0.6D, 0.8D, surface layer) velocity profile are fitted by logarithmic model, log-linear model, and extended log-linear model with the same roughness length z0 in different time section, respectively. The calculated friction velocity and friction coefficient and their correlation are discussed. The results show that the log-linear model and the log-linear extend model are closer to the measure velocity profile than that of the logarithmic model.

Accelerated Life Test Modeling of Outdoor Optical Products with Time-Varying Multi-Stresses

2008 ◽  
Vol 51 (2) ◽  
pp. 42-54
Author(s):  
Chung Lam ◽  
Huairui Guo
Keyword(s):  
Life Stress ◽  
Practical Method ◽  
Temperature Cycling ◽  
Accelerated Life Test ◽  
Indoor Environments ◽  
Time Varying ◽  
Temperature And Humidity ◽  
Cost Calculations ◽  
Log Linear ◽  
Term Performance

The long-term performance prediction of optical products deployed outdoors is important. The accuracy of the prediction directly affects warranty cost calculations. In indoor environments, products are generally operated under controlled temperature and humidity. However, products outdoors usually experience multiple stresses that continuously vary with time. An outdoor-use optical product, such as a fiber distribution hub cabinet with splitters, connectors, and fan-outs built in, will experience temperature cycling effects and varying humidity. Therefore, time-varying temperature and humidity are considered as major stresses acting on outdoor-use optical products. This study proposes a practical method that uses design of experiment (DOE) techniques and generalized log-linear (GLL) life-stress relationship to predict the life of outdoor optical products. The proposed method can consider the cumulative damage caused by time-varying temperature and humidity and was applied to predict the warranty return of an outdoor optical product.

scholarly journals On Scatterometer Ocean Stress

2009 ◽  
Vol 26 (2) ◽  
pp. 368-382 ◽  
Author(s):  
M. Portabella ◽  
A. Stoffelen
Keyword(s):  
Wind Stress ◽  
Roughness Length ◽  
Spatial Scales ◽  
Weather Prediction ◽  
Neutral Winds ◽  
Level 3 ◽  
Stress Estimation ◽  
The Stability ◽  
Ocean Wind ◽  
Level 2

Abstract Scatterometers estimate the relative atmosphere–ocean motion at spatially high resolution and provide accurate inertial-scale ocean wind forcing information, which is crucial for many ocean, atmosphere, and climate applications. An empirical scatterometer ocean stress (SOS) product is estimated and validated using available statistical information. A triple collocation dataset of scatterometer, and moored buoy and numerical weather prediction (NWP) observations together with two commonly used surface layer (SL) models are used to characterize the SOS. First, a comparison between the two SL models is performed. Although their roughness length and the stability parameterizations differ somewhat, the two models show little differences in terms of stress estimation. Second, a triple collocation exercise is conducted to assess the true and error variances explained by the observations and the SL models. The results show that the uncertainty in the NWP dataset is generally larger than in the buoy and scatterometer wind/stress datasets, but it depends on the spatial scales of interest. The triple collocation analysis also shows that scatterometer winds are as close to real winds as to equivalent neutral winds, provided that the appropriate scaling is used. An explanation for this duality is that the small stability effects found in the analysis are masked by the uncertainty in SL models and their inputs. The triple collocation analysis shows that scatterometer winds can be straightforwardly and reliably transformed to wind stress. This opens the door for the development of wind stress swath (level 2) and gridded (level 3) products for the Advanced Scatterometer (ASCAT) on board Meterological Operation (MetOp) and for further geophysical development.

scholarly journals Accuracy of retrieving temperature and humidity profiles by ground-based microwave radiometry in truly complex terrain

2015 ◽  
Vol 8 (8) ◽  
pp. 3355-3367 ◽  
Author(s):  
G. Massaro ◽  
I. Stiperski ◽  
B. Pospichal ◽  
M. W. Rotach
Keyword(s):  
Complex Terrain ◽  
Microwave Radiometer ◽  
Radiosonde Data ◽  
Alpine Valley ◽  
Topographic Slope ◽  
Retrieval Algorithms ◽  
Temperature And Humidity ◽  
Upper Level ◽  
The One ◽  
Humidity Profiles

Abstract. Within the Innsbruck Box project, a ground-based microwave radiometer (RPG-HATPRO) was operated in the Inn Valley (Austria), in very complex terrain, between September 2012 and May 2013 to obtain temperature and humidity vertical profiles of the full troposphere with a specific focus on the valley boundary layer. In order to assess its performance in a deep alpine valley, the profiles obtained by the radiometer with different retrieval algorithms based on different climatologies are compared to local radiosonde data. A retrieval that is improved with respect to the one provided by the manufacturer, based on better resolved data, shows a significantly smaller root mean square error (RMSE), both for the temperature and humidity profiles. The improvement is particularly substantial at the heights close to the mountaintop level and in the upper troposphere. Lower-level inversions, common in an alpine valley, are resolved to a satisfactory degree. On the other hand, upper-level inversions (above 1200 m) still pose a significant challenge for retrieval. For this purpose, specialized retrieval algorithms were developed by classifying the radiosonde climatologies into specialized categories according to different criteria (seasons, daytime, nighttime) and using additional regressors (e.g., measurements from mountain stations). The training and testing on the radiosonde data for these specialized categories suggests that a classification of profiles that reproduces meaningful physical characteristics can yield improved targeted specialized retrievals. A novel and very promising method of improving the profile retrieval in a mountainous region is adding further information in the retrieval, such as the surface temperature at fixed levels along a topographic slope or from nearby mountaintops.

Sign in / Sign up

Export Citation Format

Share Document