scholarly journals Geometry-Based Preliminary Quantification of Landslide-Induced Impulse Wave Attenuation in Mountain Lakes

2021 ◽  
Vol 11 (24) ◽  
pp. 11614
Author(s):  
Andrea Franco ◽  
Barbara Schneider-Muntau ◽  
Nicholas J. Roberts ◽  
John J. Clague ◽  
Bernhard Gems
Keyword(s):  
Wave Attenuation ◽  
Mountain Lakes ◽  
Flow Depth ◽  
Wave Decay ◽  
Novel Approach ◽  
Initial Stage ◽  
Decay Potential ◽  
Impulse Waves ◽  
Highly Correlated ◽  
Two Parameters

In this work, a simple methodology for preliminarily assessing the magnitude of potential landslide-induced impulse waves’ attenuation in mountain lakes is presented. A set of metrics is used to define the geometries of theoretical mountain lakes of different sizes and shapes and to simulate impulse waves in them using the hydrodynamic software Flow-3D. The modeling results provide the ‘wave decay potential’, a ratio between the maximum wave amplitude and the flow depth at the shoreline. Wave decay potential is highly correlated with what is defined as the ‘shape product’, a metric that represents lake geometry. The relation between these two parameters can be used to evaluate wave dissipation in a natural lake given its geometric properties, and thus estimate expected flow depth at the shoreline. This novel approach is tested by applying it to a real-world event, the 2007 landslide-generated wave in Chehalis Lake (Canada), where the results match well with those obtained using the empirical equation provided by ETH Zurich (2019 Edition). This work represents the initial stage in the development of this method, and it encourages additional research and modeling in which the influence of the impacting characteristics on the resulting waves and flow depths is investigated.

scholarly journals A Random Forest Model for the Prediction of FOG Content in Inlet Wastewater from Urban WWTPs

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1237
Author(s):  
Vanesa Mateo Pérez ◽  
José Manuel Mesa Fernández ◽  
Joaquín Villanueva Balsera ◽  
Cristina Alonso Álvarez
Keyword(s):  
Random Forest ◽  
Wastewater Treatment Plants ◽  
Learning Algorithm ◽  
Global Improvement ◽  
Treatment Processes ◽  
Early Adoption ◽  
Novel Approach ◽  
Number Of Factors ◽  
Initial Stage ◽  
Correct Design

The content of fats, oils, and greases (FOG) in wastewater, as a result of food preparation, both in homes and in different commercial and industrial activities, is a growing problem. In addition to the blockages generated in the sanitary networks, it also represents a difficulty for the performance of wastewater treatment plants (WWTP), increasing energy and maintenance costs and worsening the performance of downstream treatment processes. The pretreatment stage of these facilities is responsible for removing most of the FOG to avoid these problems. However, so far, optimization has been limited to the correct design and initial installation dimensioning. Proper management of this initial stage is left to the experience of the operators to adjust the process when changes occur in the characteristics of the wastewater inlet. The main difficulty is the large number of factors influencing these changes. In this work, a prediction model of the FOG content in the inlet water is presented. The model is capable of correctly predicting 98.45% of the cases in training and 72.73% in testing, with a relative error of 10%. It was developed using random forest (RF) and the good results obtained (R2 = 0.9348 and RMSE = 0.089 in test) will make it possible to improve operations in this initial stage. The good features of this machine learning algorithm had not been used, so far, in the modeling of pretreatment parameters. This novel approach will result in a global improvement in the performance of this type of facility allowing early adoption of adjustments to the pretreatment process to remove the maximum amount of FOG.

Relative consumption, relative wealth, and long-run growth: when and why is the standard analysis prone to incorrect conclusions?

2021 ◽  
pp. 1-25
Author(s):  
Franz X. Hof ◽  
Klaus Prettner
Keyword(s):  
Growth Rate ◽  
Traditional Approach ◽  
Total Change ◽  
Relative Consumption ◽  
Fundamental Factor ◽  
Elasticity Of Intertemporal Substitution ◽  
Relative Wealth ◽  
Novel Approach ◽  
Long Run ◽  
Two Parameters

Abstract We employ a novel approach for analyzing the effects of relative consumption and relative wealth preferences on economic growth. In the pertinent literature, these effects are usually assessed by examining the dependence of the growth rate on the two parameters of the utility function that seem to measure the strength of the relative consumption and the relative wealth motives. Applying our fundamental factor approach, we identify specifications in which the traditional approach yields incorrect qualitative conclusions. The problematic specifications have the common unpleasant property that the parameter that seems to determine the strength of the relative consumption motive actually also affects the elasticity of intertemporal substitution of absolute consumption (and the strength of the relative wealth motive). Since the standard approach is unaware of the additional effect(s), it attributes the total change in the growth rate incorrectly to the change in the strength of the relative consumption motive.

Assessment of the wave attenuation capacity of a mangrove forest based on its age and the incident wave conditions

2020 ◽  
Author(s):  
Maria Maza ◽  
Javier L. Lara ◽  
Iñigo J. Losada
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Mangrove Forest ◽  
Wave Attenuation ◽  
Volume Fraction ◽  
Coastal Protection ◽  
Local Flow ◽  
Ecosystem Properties ◽  
Wave Decay ◽  
Wave Conditions

<p>Although mangroves reduce annual flooding to millions of people there is not a methodology to implement these solutions and it is still difficult to estimate the protection provided by them under different environmental conditions and ecosystem properties. To move forward in the consecution of an engineering approach when implementing these solutions for coastal defense, the first step to make is to better understand and parameterize the basic physical processes involved in flow-mangroves interaction. With the aim of getting a new formulation for wave decay provided by Rhizophora mangrove forests based on flow and ecosystem properties, an experimental campaign was carried out where both wave attenuation and forces on mangrove individuals were measured under different wave conditions. Both, the hydrodynamic conditions and the mangrove forest, were scaled according to field conditions for short waves. The detailed wave attenuation and drag force measurements obtained in these experiments allowed to obtain new formulations of wave decay produced by the forest depending on the flow, i.e.: water depth, wave height and period, and on the forest characteristics, i.e.: individuals submerged solid volume fraction and density. These formulations are used to get attenuation rates under different flow and ecosystem conditions. The resultant curves provide with the wave decay produced by a specific Rhizophora forest subjected to the defined wave conditions. The forest is defined on the basis of its age, considering the differences in individual trees depending on their maturity and the density of the forest as the number of trees per unit area. Wave conditions are defined by the root mean square wave height and the peak period and water depth is also considered. The obtained curves allow to estimate the width of the forest necessary to reach a certain level of protection considering the local flow conditions and the forest age. This can assist in the inclusion of nature-based solutions in the portfolio of coastal protection measures.</p>

Spectral Modeling of Ice-Induced Wave Decay

2020 ◽  
Vol 50 (6) ◽  
pp. 1583-1604 ◽  
Author(s):  
Qingxiang Liu ◽  
W. Erick Rogers ◽  
Alexander Babanin ◽  
Jingkai Li ◽  
Changlong Guan
Keyword(s):  
Wave Height ◽  
Wave Attenuation ◽  
Wave Spectrum ◽  
Wave Model ◽  
Beaufort Sea ◽  
Peak Frequency ◽  
Large Wave ◽  
Wave Decay ◽  
Operational Forecasts ◽  
The Antarctic

AbstractThree dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral wave model WAVEWATCH III to estimate the ice-induced wave attenuation rate. These models are then explored and intercompared through hindcasts of two field cases: one in the autumn Beaufort Sea in 2015 and the other in the Antarctic marginal ice zone (MIZ) in 2012. The capability of these dissipative models, along with their limitations and applicability to operational forecasts, are analyzed and discussed. The sensitivity of the simulated wave height to different source terms—the ice-induced wave decay Sice and other physical processes Sother (e.g., wind input, nonlinear four-wave interactions)—is also investigated. For the Antarctic MIZ experiment, Sother is found to be remarkably less than Sice and thus contributes little to the simulated significant wave height Hs. The saturation of dHs/dx at large wave heights in this case, as reported by a previous study, is well reproduced by the three dissipative ice models with or without the utilization of Sother in the ice-infested seas. A clear downward trend in the peak frequency fp is found as Hs increases. As fp decreases, the dominant wave components of a wave spectrum will experience reduced damping by sea ice, and finally result in the flattening of dHs/dx for Hs > 3 m in this specific case. Nonetheless, Sother should not be disregarded within a more general modeling perspective, as our simulations suggest Sother could be comparable to Sice in the Beaufort Sea case where wave and ice conditions are remarkably different.

High-Resolution Paleoclimatic Information from Chinese Eolian Sediments Based on Grayscale Intensity Profiles

2000 ◽  
Vol 53 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Magnetic Susceptibility ◽  
High Resolution ◽  
Digital Camera ◽  
Dune Sand ◽  
Laptop Computer ◽  
Chinese Loess ◽  
Proxy Records ◽  
Eolian Sediments ◽  
Highly Correlated ◽  
Two Parameters

AbstractGrayscale intensity profiles from photographic images offer a rapid means of obtaining paleoclimate proxy records from Chinese loess, dune sand, and paleosols. Although the data can be obtained using conventional 35-mm film images, a digital camera and laptop computer will produce a high-resolution grayscale profile at a field site within minutes. Comparison of grayscale profiles with profiles of magnetic susceptibility measured down loess and dune-sand sections at sites on the Loess Plateau and Tibetan Plateau in a range of altitudes and climatic regimes shows that the two parameters are highly correlated. Therefore, grayscale intensity is a convenient alternative to magnetic susceptibility for generating paleoclimatic data in the loess and desert-margin regions of China. The resolution of both grayscale and susceptibility profiles ultimately is limited by bioturbation, which is most pronounced in paleosols.

scholarly journals Estimation of Scintillation Indices: A Novel Approach Based on Local Kernel Regression Methods

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
Mohammed Ouassou ◽  
Oddgeir Kristiansen ◽  
Jon G. O. Gjevestad ◽  
Knut Stanley Jacobsen ◽  
Yngvild L. Andalsvik
Keyword(s):  
Information Criteria ◽  
Ionospheric Scintillation ◽  
Local Regression ◽  
Regression Methods ◽  
Novel Approach ◽  
Low Pass ◽  
Discontinuous Phase ◽  
Novel Method ◽  
Highly Correlated ◽  
Scintillation Indices

We present a comparative study of computational methods for estimation of ionospheric scintillation indices. First, we review the conventional approaches based on Fourier transformation and low-pass/high-pass frequency filtration. Next, we introduce a novel method based on nonparametric local regression with bias Corrected Akaike Information Criteria (AICC). All methods are then applied to data from the Norwegian Regional Ionospheric Scintillation Network (NRISN), which is shown to be dominated by phase scintillation and not amplitude scintillation. We find that all methods provide highly correlated results, demonstrating the validity of the new approach to this problem. All methods are shown to be very sensitive to filter characteristics and the averaging interval. Finally, we find that the new method is more robust to discontinuous phase observations than conventional methods.

scholarly journals Hanging glacier monitoring with icequake repeaters and seismic coda wave interferometry: a case study of the Eiger hanging glacier

2021 ◽  
Author(s):  
Małgorzata Chmiel ◽  
Fabian Walter ◽  
Lukas Preiswerk ◽  
Martin Funk ◽  
Lorenz Meier ◽  
...  
Keyword(s):  
Large Scale ◽  
Wave Attenuation ◽  
Seismic Velocity ◽  
Swiss Alps ◽  
Coda Wave ◽  
Diurnal Cycles ◽  
Ice Surface ◽  
Novel Approach ◽  
Seismic Coda ◽  
Coda Wave Interferometry

Abstract. Driven by the force of gravity, hanging glacier instabilities can lead to catastrophic rupture events. Reliable forecasting remains a challenge as englacial damage leading to large-scale failure is masked from modern sensing technology focusing on the ice surface. The Eiger hanging glacier, located in the Swiss Alps, was intensely monitored between April and August 2016 before a moderate 15,000 m3 break-off event from the ice cliff. Among different instruments, such as an automatic camera and interferometric radar, four 3-component seismometers were installed on the glacier. A single seismometer operated throughout the whole monitoring period. It recorded over 200,000 repeating icequakes showing strong englacial seismic coda waves. We propose a novel approach for hanging glacier monitoring by combining repeating icequake analysis, coda wave interferometry, and attenuation measurements. Our results show a seasonal 0.1 % decrease in relative englacial seismic velocity dv/v and an increase in coda wave attenuation Qc−1 (Qc decreases from ~50 to ~30). Comparison of dv/v and Qc with air temperature suggests that these changes are driven by a seasonal increase in the glacier’s ice and firn pack temperature that might affect the top 20 m of the glacier. Diurnal cycles of Qc−1, repeating icequake activity, and the velocity of the glacier front shift from cosinusoidal to sinusoidal variations under the presence of meltwater. The proposed approach extends the monitoring of the hanging glacier beyond the ice surface and allows for a better understanding of the glacier’s response to time-dependent external forcing, which is an important step towards improved break-off forecasting systems.

The “cheerleader effect” in facial and bodily attractiveness: A result of memory bias and not perceptual encoding

2020 ◽  
pp. 174702182097608
Author(s):  
Jean YJ Hsieh ◽  
O Scott Gwinn ◽  
Kevin R Brooks ◽  
Ian D Stephen ◽  
Daniel J Carragher ◽  
...  
Keyword(s):  
Memory Bias ◽  
Memory Condition ◽  
Body Images ◽  
Perceptual Condition ◽  
Initial Stage ◽  
Two Parameters

Individual faces are rated as more attractive when presented in a group compared with when presented individually; a finding dubbed the “cheerleader effect.” As a relatively recent discovery, the conditions necessary to observe the effect are not clearly understood. We sought to better define these conditions by examining two parameters associated with the effect. Our first aim was to determine whether the effect is specific to faces or occurs also for human bodies. Both face and body images were rated as being more attractive when presented in groups than when presented in isolation, demonstrating that the cheerleader effect is not restricted to faces. Furthermore, the effect was significantly larger for bodies than faces. Our second aim was to determine whether the cheerleader effect originates from a bias in memory or occurs during perceptual encoding. Participants in the “memory” condition provided attractiveness ratings after images had been removed from the testing screen, whereas participants in the “perceptual” condition provided ratings while the images remained visible, thereby eliminating the memory components of the paradigm. Significant cheerleader effects were only observed in the memory condition. We conclude that the cheerleader effect for faces and bodies is due to a bias in memory and does not occur at an initial stage of perceptual encoding.

scholarly journals Scour Evolution Downstream of Submerged Weirs in Clear Water Scour Conditions

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1746 ◽  
Author(s):  
Dawei Guan ◽  
Jingang Liu ◽  
Yee-Meng Chiew ◽  
Yingzheng Zhou
Keyword(s):  
Coarse Sand ◽  
Analytical Models ◽  
Scour Depth ◽  
Coastal Environments ◽  
Flow Depth ◽  
Clear Water ◽  
Submerged Condition ◽  
Initial Stage ◽  
Scour Hole ◽  
Weir Height

Although weirs or dikes in the riverine and coastal environments are frequently overtopped, few studies have hitherto examined the evolution of the scour process downstream of these structures under the submerged condition. This paper presents an experimental investigation on time evolution of the scour process downstream of submerged weirs with a uniform coarse sand. The clear-water scour experiments were carried out in a tilting recirculation flume. Different flow intensities and overtopping ratios (approach flow depth/weir height) were adopted in the experiments. Experimental observations show that the scour hole downstream of submerged weirs develops very fast in the initial stage, before progressing at a decreasing rate and eventually reaching the equilibrium stage. The results show that an increase of the overtopping ratio or flowrate can generate larger scour depth and volume downstream of the weir. Moreover, geometrical similarity of the scour hole that formed downstream of the weir was observed in the tests. Finally, empirical equations for predicting scour hole geometrical evolutions downstream of the submerged weirs were presented. The results of this study are useful in the development of numerical/analytical models capable of estimating the scour depth downstream of weirs in the river or coastal areas, for which the overtopping conditions are present.

The comparative significance and utility of the Freundlich and Langmuir parameters for characterizing sorption and plant availability of phosphate in soils

Soil Research ◽  
1982 ◽  
Vol 20 (3) ◽  
pp. 233 ◽  
Author(s):  
ICR Holford
Keyword(s):  
Sorption Capacity ◽  
Plant Uptake ◽  
Langmuir Equation ◽  
Plant Availability ◽  
Phosphate Sorption ◽  
Surface Equation ◽  
Highly Correlated ◽  
Two Parameters

In studies using 62 Australian and English soils, the two parameters of the Freundlich sorption equation were compared with phosphate sorption capacity, calculated from the Langmuir 'two-surface' equation, and sorptivity and affinity indices calculated from the simple Langmuir equation applied to an isotherm concentration range of 0-5�g phosphorus/ml. The Freundlich extensive parameter was most highly correlated with sorptivity, and to a decreasing extent with sorption capacity and affinity. It appears to be fundamentally a sorptivity index which reflects the sorption capacity more than the affinity component of sorption, although greatly underestimating sorption capacity. The reciprocal of the Freundlich exponent proved to be an affinity parameter and was most useful in this role on soils of similar sorption capacity. However, conflicting results on different groups of soils showed that this parameter was less distinctive in its role than the others. Studies on two different groups of soils showed that the sorptivity and affinity parameters from the Langmuir equation accounted for more of the variance in plant uptake of labile phosphate than the Freundlich parameters.

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