scholarly journals The influence of layer-interface geometry on single-layer folding

2018 ◽  
Vol 487 (1) ◽  
pp. 59-79 ◽  
Author(s):  
Albert Griera ◽  
Enrique Gomez-Rivas ◽  
Maria-Gema Llorens
Keyword(s):  
Lower Layer ◽  
Wide Spectrum ◽  
Single Layer ◽  
Structural Inheritance ◽  
Kinematic Indicators ◽  
Longitudinal Asymmetry ◽  
Shear Component ◽  
Two Parameters ◽  
Interface Geometry ◽  
Component Parallel

AbstractGeometrical heterogeneities along layer interfaces play a key role in determining the geometries of folds developed during shortening of competent layers. We present a series of numerical simulations to investigate the influence of initial sinusoidal perturbations on the folding of single layers. Models consist of a competent viscous single layer embedded in a softer matrix, with the layer orientated parallel to the shortening direction. We first generalize the wide spectrum of sinusoidal perturbations accounting for asymmetries along and across a competent single layer, using two parameters: transversal asymmetry (A′) and longitudinal asymmetry (φ). These two parameters allow the transition between classical fold shapes and pinch and swell geometries to be studied. The parameter A′ describes the development of fold hinges with different geometries between the upper and lower layer interfaces, and abnormal curvatures between the outer and inner arcs of fold hinges. The parameter φ induces a strong polarity on the folds, with a systematic preferred orientation of the pinch and swell regions of the layer, even if there is no shear component parallel to the layer. Our results demonstrate the importance of structural inheritance on the resulting fold geometries, and suggest that caution must be taken when using certain types of asymmetrical folds as strain markers and kinematic indicators.

The hydraulics of two flowing layers with different densities

1986 ◽  
Vol 163 ◽  
pp. 27-58 ◽  
Author(s):  
Laurence Armi
Keyword(s):  
Lower Layer ◽  
Single Layer ◽  
Critical Conditions ◽  
Hydraulic Jumps ◽  
Flow Configurations ◽  
Pass Through ◽  
Bottom Depth ◽  
Downstream Flow ◽  
Energy Equations ◽  
Simple Flow

This is a theoretical and experimental study of the basic hydraulics of two flowing layers. Unlike single-layer flows, two-layer flows respond quite differently to bottom depth as opposed to width variations. Bottom-depth changes affect the lower layer directly and the upper layer only indirectly. Changes in width can affect both layers. In fact for flows through a contraction control two distinct flow configurations are possible; which one actually occurs depends on the requirements of matching a downstream flow. Two-layer flows can pass through internally critical conditions at other than the narrowest section. When the two layers are flowing in the same direction, the result is a strong coupling between the two layers in the neighbourhood of the control. For contractions a particularly simple flow then exists upstream in which there is no longer any significant interfacial dynamics; downstream in the divergent section the flow remains internally supercritical, causing one of the layers to be rapidly accelerated with a resulting instability at the interface. A brief discussion of internal hydraulic jumps based upon the energy equations as opposed to the more traditional momentum equations is included. Previous uniqueness problems are thereby avoided.

scholarly journals Characteristics of Oceanic Warm Cloud Layers within Multilevel Cloud Systems Derived by Satellite Measurements

Atmosphere ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 465 ◽  
Author(s):  
Yuhao Ding ◽  
Qi Liu ◽  
Ping Lao
Keyword(s):  
Double Layer ◽  
Lower Layer ◽  
Single Layer ◽  
Distribution Patterns ◽  
Radar Data ◽  
Multilayered Structures ◽  
Layer System ◽  
Cloud Systems ◽  
Warm Cloud ◽  
Double Layer System

Low-level warm clouds are a major component in multilayered cloud systems and they are generally hidden from the top-down view of satellites with passive measurements. This study conducts an investigation on oceanic warm clouds embedded in multilayered structures by using spaceborne radar data with fine vertical resolution. The occurrences of warm cloud overlapping and the geometric features of several kinds of warm cloud layers are examined. It is found that there are three main types of cloud systems that involve warm cloud layers, including warm single layer clouds, cold-warm double layer clouds, and warm-warm double layer clouds. The two types of double layer clouds account for 23% and in the double layer occurrences warm-warm double layer subsets contribute about 13%. The global distribution patterns of these three types differ from each other. Single-layer warm clouds and the lower warm clouds in the cold-warm double layer system they have nearly identical geometric parameters, while the upper and lower layer warm clouds in the warm-warm double layer system are distinct from the previous two forms of warm cloud layers. In contrast to the independence of the two cloud layers in cold-warm double layer system, the two kinds of warm cloud layers in the warm-warm double layer system may be coupled. The distance between the two layers in the warm-warm double layer system is weakly dependent on cloud thickness. Given the upper and lower cloud layer with moderate thickness of around 1 km, the cloudless gap reaches its maximum when exceeding 600 m. The cloudless gap decreases in thickness as the two cloud layers become even thinner or thicker.

scholarly journals The interaction of waves with horizontal cylinders in two-layer fluids

1995 ◽  
Vol 304 ◽  
pp. 213-229 ◽  
Author(s):  
C. M. Linton ◽  
M. McIver
Keyword(s):  
Lower Layer ◽  
Single Layer ◽  
Wave Theory ◽  
Finite Depth ◽  
Scattering Problems ◽  
Infinite Layer ◽  
Linear Water Wave Theory ◽  
Interaction Of Waves ◽  
Reciprocity Relations ◽  
Horizontal Cylinders

We consider two-dimensional problems based on linear water wave theory concerning the interaction of waves with horizontal cylinders in a fluid consisting of a layer of finite depth bounded above by a free surface and below by an infinite layer of fluid of greater density. For such a situation time-harmonic waves can propagate with two different wavenumbers K and k. In a single-layer fluid there are a number of reciprocity relations that exist connecting the various hydrodynamic quantities that arise. These relations are systematically extended to the two-fluid case. It is shown that for symmetric bodies the solutions to scattering problems where the incident wave has wavenumber K and those where it has wavenumber k are related so that the solution to both can be found by just solving one of them. The particular problems of wave scattering by a horizontal circular cylinder in either the upper or lower layer are then solved using multipole expansions.

scholarly journals Three-dimensional water-wave scattering in two-layer fluids

2000 ◽  
Vol 423 ◽  
pp. 155-173 ◽  
Author(s):  
J. R. CADBY ◽  
C. M. LINTON
Keyword(s):  
Water Wave ◽  
Lower Layer ◽  
Three Dimensional ◽  
Single Layer ◽  
Wave Theory ◽  
Finite Depth ◽  
Wave Radiation ◽  
Infinite Layer ◽  
Linear Water Wave Theory ◽  
Submerged Sphere

We consider, using linear water-wave theory, three-dimensional problems concerning the interaction of waves with structures in a fluid which contains a layer of finite depth bounded above by a free surface and below by an infinite layer of fluid of greater density. For such a situation time-harmonic waves can propagate with two different wavenumbers K and k. In a single-layer fluid there are a number of reciprocity relations that exist connecting the various hydrodynamic quantities that arise, and these relations are systematically extended to the two-fluid case. The particular problems of wave radiation and scattering by a submerged sphere in either the upper or lower layer are then solved using multipole expansions.

scholarly journals Hierarchical Distribution Matching for Probabilistic Amplitude Shaping

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 958
Author(s):  
Stella Civelli ◽  
Marco Secondini
Keyword(s):  
Lower Layer ◽  
Minimum Energy ◽  
Single Layer ◽  
Low Complexity ◽  
Design Guidelines ◽  
Constant Composition ◽  
Distribution Matching ◽  
Practical Design ◽  
Rate Loss ◽  
Complexity Increase

Probabilistic amplitude shaping—implemented through a distribution matcher (DM)—is an effective approach to enhance the performance and the flexibility of bandwidth-efficient coded modulations. Different DM structures have been proposed in the literature. Typically, both their performance and their complexity increase with the block length. In this work, we present a hierarchical DM (Hi-DM) approach based on the combination of several DMs of different possible types, which provides the good performance of long DMs with the low complexity of several short DMs. The DMs are organized in layers. Each upper-layer DM encodes information on a sequence of lower-layer DMs, which are used as “virtual symbols”. First, we describe the Hi-DM structure, its properties, and the encoding and decoding procedures. Then, we present three particular Hi-DM configurations, providing some practical design guidelines, and investigating their performance in terms of rate loss and energy loss. Finally, we compare the system performance obtained with the proposed Hi-DM structures and with their single-layer counterparts: a 0.19dB SNR gain is obtained by a two-layer Hi-DM based on constant composition DMs (CCDM) compared to a single-layer CCDM with same complexity; a 0.12dB gain and a significant complexity reduction are obtained by a Hi-DM based on minimum-energy lookup tables compared to a single-layer DM based on enumerative sphere shaping with same memory requirements.

Oceanic warm cloud layers within multilevel cloud systems observed by satellite measurements

2020 ◽  
Author(s):  
Qi Liu ◽  
Yuhao Ding ◽  
Ping Lao
Keyword(s):  
Double Layer ◽  
Radiative Forcing ◽  
Lower Layer ◽  
Numerical Models ◽  
Three Dimensional ◽  
Single Layer ◽  
Layer System ◽  
Cloud Systems ◽  
Warm Cloud ◽  
Double Layer System

<p>Low-level warm clouds are a major component in multilayered cloud systems and are generally hidden from the top-down view of satellites with passive measurements. By using spaceborne radar data with fine vertical resolution, this study conducts an investigation on oceanic warm clouds embedded in multilayered structures. The occurrences of warm cloud overlapping and the geometric features of several kinds of warm cloud layers are examined. It is found that there are three main types of cloud systems that involve warm cloud layers, including warm single layer clouds, cold-warm double layer clouds and warm-warm double layer clouds. The two types of double layer clouds account for 23% and in the double layer occurrences warm-warm double layer subsets contribute about 13%. The global distribution patterns of these three types differ from each other. Single-layer warm clouds and the lower warm clouds in the cold-warm double layer system have nearly identical geometric parameters, while the upper and lower layer warm clouds in the warm-warm double layer system are distinct from the previous two forms of warm cloud layers. In contrast to the independence of the two cloud layers in cold-warm double layer system, the two kinds of warm cloud layers in the warm-warm double layer system may be coupled. The distance between the two layers in the warm-warm double layer system is weakly dependent on cloud thickness. Given the upper and lower cloud layer with moderate thickness around 1 km, the cloudless gap reaches its maximum exceeding 600 m. As the two cloud layers become even thinner or thicker, the cloudless gap decreases in thickness. It is believed that such knowledge on cloud overlapping is critical for fully understanding the distribution of warm clouds in three-dimensional space. The results derived in this study could help validating cloud results of numerical models, which are indeed three-dimensional in nature. They could also be used to improve the estimation of cloud radiative forcing, since it is affected by cloud occurrences and especially their vertical structures. It should be pointed out that solid explanations for the above cloud features cannot be presented by only using these satellite data themselves. </p>

scholarly journals Cloud vertical structure over a tropical station obtained using long-term high resolution Radiosonde measurements

2018 ◽  
Author(s):  
Nelli Narendra Reddy ◽  
Madineni Venkat Ratnam ◽  
Ghouse Basha ◽  
Varaha Ravikiran
Keyword(s):  
Large Scale ◽  
Vertical Structure ◽  
Lower Layer ◽  
Monsoon Season ◽  
Single Layer ◽  
Cloud Base ◽  
High Level ◽  
Tropical Station ◽  
Layer Cloud

Abstract. Cloud vertical structure, including top and base altitudes, thickness of cloud layers, and the vertical distribution of multi-layer clouds affects the large-scale atmosphere circulation by altering gradients in the total diabatic heating/cooling and latent heat release. In this study, long-term (11 years) observations of high vertical resolution radiosondes are used to obtain the cloud vertical structure over a tropical station, Gadanki (13.5° N, 79.2° E), India. The detected cloud layers are verified with independent observations using cloud particle sensor (CPS) sonde launched from the same station. High-level clouds account for 69.05 %, 58.49 %, 55.5 %, and 58.6 % of all clouds during pre-monsoon, monsoon, post-monsoon, and winter seasons, respectively. The average cloud base (cloud top) altitude for low-level, middle-level, high-level and deep convective clouds are 1.74 km (3.16 km), 3.59 km (5.55 km), 8.79 km (10.49 km), and 1.22 km (11.45 km), respectively. Single-layer, two-layer, and three-layer clouds account for 40.80 %, 30.71 %, and 19.68 % of all cloud configurations, respectively. Multi-layer clouds occurred more frequently during the monsoon with 34.58 %. Maximum cloud top altitude and the cloud thickness occurred during monsoon season for single-layer clouds and the uppermost layer of multiple layer cloud configurations. In multi-layer cloud configurations, diurnal variations in the thickness of upper layer clouds are larger than those of lower layer clouds. Heating/cooling in the troposphere and lower stratosphere due to these clouds layers is also investigated and found peak cooling (peak warming) below (above) the Cold Point Tropopause (CPT) altitude. The magnitude of cooling (warming) increases from single-layer to four or more-layer cloud occurrence. Further, the vertical structure of clouds is also studied with respect to the arrival date of Indian summer monsoon over Gadanki.

scholarly journals Country centrality in the international multiplex network

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Giovanni Bonaccorsi ◽  
Massimo Riccaboni ◽  
Giorgio Fagiolo ◽  
Gianluca Santoni
Keyword(s):  
Cross Sections ◽  
Wide Spectrum ◽  
Single Layer ◽  
The Other ◽  
Gdp Per Capita ◽  
Centrality Measures ◽  
Multiplex Network ◽  
Per Capita

AbstractIn this work we introduce and analyze a new and comprehensive multilayer dataset covering a wide spectrum of international relationships between coutries. We select two cross sections of the dataset corresponding to years 2003 and 2010 with 19 layers and 112 nodes to study the structure and evolution of the network. Country centrality is measured by the multiplex PageRank (MultiRank) and the multiplex hub and authority scores (MultiHub and MultiAuth). We find that the MultiHub measure has the highest correlation to GDP per capita, with respect to the other multilayer measures and to their single layer analogues. Finally we analyze the differences in the ranking between GDP per capita and the multilayer centrality measures to evaluate them as measures of development.

The Calculation of the Two-Layer Beam Model on an Elastic Basis with Variable Modulus of Subgrade Reaction

2013 ◽  
Vol 351-352 ◽  
pp. 566-569 ◽  
Author(s):  
Vladimir Igorevich Andreev ◽  
Alena Vladimirovna Matveeva ◽  
Elena Vjacheslavovna Barmenkova
Keyword(s):  
Lower Layer ◽  
Single Layer ◽  
Beam Model ◽  
Constant Modulus ◽  
Subgrade Reaction ◽  
Variable Rigidity ◽  
Modulus Of Subgrade Reaction ◽  
Variable Modulus ◽  
Internal Forces ◽  
Elastic Basis

In the present paper is given the calculation of the two-layer and the single-layer beam models on an elastic basis with variable and constant modulus of subgrade reaction. The two-layer beam is the beam of variable rigidity, the lower layer simulates the foundation, and the upper - the structure, at the same time is considered the weight of each layer. In the results of calculations of beams, as the two-layer and the single-layer, the values of the internal forces and stresses are obtained more with variable modulus of subgrade reaction than with constant. With consideration of the two-layer and the single-layer beam models with the same characteristics of the base, the values of internal forces, generated in two-layer beams, are obtained much more.

scholarly journals Quenching active swarms: effects of light exposure on collective motility in swarming Serratia marcescens

2019 ◽  
Vol 16 (156) ◽  
pp. 20180960 ◽  
Author(s):  
Junyi Yang ◽  
Paulo E. Arratia ◽  
Alison E. Patteson ◽  
Arvind Gopinath
Keyword(s):  
Serratia Marcescens ◽  
Brownian Dynamics ◽  
Large Scale ◽  
Light Exposure ◽  
Wide Spectrum ◽  
Dynamics Model ◽  
Planktonic Bacteria ◽  
Starting Point ◽  
Active Bacteria ◽  
Two Parameters

Swarming colonies of the light-responsive bacteria Serratia marcescens grown on agar exhibit robust fluctuating large-scale flows that include arrayed vortices, jets and sinuous streamers. We study the immobilization and quenching of these collective flows when the moving swarm is exposed to intense wide-spectrum light with a substantial ultraviolet component. We map the emergent response of the swarm to light in terms of two parameters—light intensity and duration of exposure—and identify the conditions under which collective motility is impacted. For small exposure times and/or low intensities, we find collective motility to be negligibly affected. Increasing exposure times and/or intensity to higher values suppresses collective motility but only temporarily. Terminating exposure allows bacteria to recover and eventually reestablish collective flows similar to that seen in unexposed swarms. For long exposure times or at high intensities, exposed bacteria become paralysed and form aligned, jammed regions where macroscopic speeds reduce to zero. The effective size of the quenched region increases with time and saturates to approximately the extent of the illuminated region. Post-exposure, active bacteria dislodge immotile bacteria; initial dissolution rates are strongly dependent on duration of exposure. Based on our experimental observations, we propose a minimal Brownian dynamics model to examine the escape of exposed bacteria from the region of exposure. Our results complement studies on planktonic bacteria, inform models of patterning in gradated illumination and provide a starting point for the study of specific wavelengths on swarming bacteria.

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