scholarly journals Mathematical Model Studies for River Regulatory Measures for the Improvement of Draft in Hoogly Estuary, India

2014 ◽  
Vol 2 ◽  
pp. 1-12 ◽  
Author(s):  
Rajesh P. Dubey ◽  
S. Samarawickrama ◽  
P.P. Gunaratna ◽  
L. Halgahawatta ◽  
K.P.P. Pathirana ◽  
...  
Keyword(s):  
Numerical Models ◽  
Field Investigation ◽  
Hydrodynamic Modelling ◽  
Model Studies ◽  
Bathymetric Data ◽  
Approach Channel ◽  
Regulatory Measures ◽  
Maintenance Dredging ◽  
Mike 21

The Haldia port is situated in the Hooghly estuary, 104 km downstream of Kolkata Port. As a result of high sedimentation, the navigational channel to the Haldia Port is maintained with great amount of dredging (25 MCM per Annum). The paper presents a study carried out to find a solution to improve the channel depth together with minimum maintenance dredging. A desk study was carried out to identify the historical formation of the estuary and the remedial measures implemented in the past. A detailed field investigation was carried out to obtain the relevant data for the calibration of numerical models. 1D (MIKE 11) river hydrodynamic modelling was carried out using the available bathymetric data to supply upstream boundary conditions for the 2D (MIKE 21) and 3D (MIKE 3) numerical models. Number of possible scenarios were tested through MIKE 21 hydrodynamic modelling to select more feasible options. Selected options were further assessed through morphodynamic and 3D hydrodynamic modelling to examine the long term sustainability of the proposed solutions. Finally, the option which comprise of; approach channel through Balari Passage & closure of the Shore Attached Channel was selected as the best option. The selected option was further studied taking navigational aspects, dredging efforts and construction sequence into consideration.

Influence of river pattern and sediment input on estuary morphology

2020 ◽  
Author(s):  
Anne Baar ◽  
Elena Bastianon ◽  
Lisanne Braat ◽  
Daniel Parsons
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Numerical Models ◽  
Sediment Supply ◽  
Tidal Amplitude ◽  
Model Studies ◽  
Braiding Index ◽  
Sediment Input ◽  
River Pattern

<p>Alluvial estuaries are dynamic landscapes that are very sensitive to changes in boundary conditions such as river discharge and sediment supply. A better understanding of the influence of upstream river discharge and sediment input on the development of estuaries under various scenarios requires long-term morphodynamic models, to both predict future changes and improve geological interpretations by storing the stratigraphy. Past 1D model studies have shown that upstream river discharge has a significant effect on the equilibrium bed profile of estuaries, but these studies ignore the effect of 2D bar and channel formation. Using 2D numerical models to predict the development of these systems on the scale of millennia proved to be difficult, since the modelled morphology is very sensitive to the choice in e.g. sediment transport predictor and bed slope effect. In this study, we use the knowledge of previous research that determined best parameter settings for realistic river and bar patterns to model long-term and large-scale estuary morphodynamics in Delft3D. Our objective is to quantify the effects of river discharge and sediment supply on the shape of estuaries and its deposits. Firstly, we systematically varied upstream river width and tidal amplitude to examine the relation between upstream river pattern and estuary dimensions. We quantified e.g. braiding index, bar dimensions, and tidal excursion length. Results show that flood flow velocities and tidal prism are less influenced by river discharge than suggested by 1D models, and are significantly influenced by the braiding index of the river. With relatively high tides, estuary bar patterns depend on tidal amplitude, while with lower tides estuary depth and braiding index are related to upstream river width and discharge. Next steps will include varying discharge to study the effect on the rate of adaptation of the river and estuary, and varying the grain size of the sediment input at the upstream boundary. We will input coarse sediment to explore differences between fluvial deposits and tidal currents, and fine sediment to use the model for research related to biofilm.</p>

scholarly journals A global association between Covid-19 cases and airborne particulate matter at regional level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Angelo Solimini ◽  
F. Filipponi ◽  
D. Alunni Fegatelli ◽  
B. Caputo ◽  
C. M. De Marco ◽  
...  
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Negative Binomial ◽  
Numerical Models ◽  
Regional Level ◽  
Pollution Level ◽  
Observation Data ◽  
Cumulative Number ◽  
Mixed Effect

AbstractEvidences of an association between air pollution and Covid-19 infections are mixed and inconclusive. We conducted an ecological analysis at regional scale of long-term exposure to air-borne particle matter and spread of Covid-19 cases during the first wave of epidemics. Global air pollution and climate data were calculated from satellite earth observation data assimilated into numerical models at 10 km resolution. Main outcome was defined as the cumulative number of cases of Covid-19 in the 14 days following the date when > 10 cumulative cases were reported. Negative binomial mixed effect models were applied to estimate the associations between the outcome and long-term exposure to air pollution at the regional level (PM10, PM2.5), after adjusting for relevant regional and country level covariates and spatial correlation. In total we collected 237,749 Covid-19 cases from 730 regions, 63 countries and 5 continents at May 30, 2020. A 10 μg/m3 increase of pollution level was associated with 8.1% (95% CI 5.4%, 10.5%) and 11.5% (95% CI 7.8%, 14.9%) increases in the number of cases in a 14 days window, for PM2.5 and PM10 respectively. We found an association between Covid-19 cases and air pollution suggestive of a possible causal link among particulate matter levels and incidence of COVID-19.

Plasmodium knowlesi: a relevant, versatile experimental malaria model

Parasitology ◽  
2016 ◽  
Vol 145 (1) ◽  
pp. 56-70 ◽  
Author(s):  
ERICA M. PASINI ◽  
ANNE-MARIE ZEEMAN ◽  
ANNEMARIE VOORBERG-VAN DER WEL ◽  
CLEMENS H. M. KOCKEN
Keyword(s):  
Parasite Species ◽  
Vaccine Development ◽  
Plasmodium Knowlesi ◽  
Host Interactions ◽  
Model Studies ◽  
Human Red Blood Cells ◽  
Malaria Model ◽  
Human Primate

SUMMARYThe primate malariaPlasmodium knowlesihas a long-standing history as an experimental malaria model. Studies using this model parasite in combination with its various natural and experimental non-human primate hosts have led to important advances in vaccine development and in our understanding of malaria invasion, immunology and parasite–host interactions. The adaptation to long-termin vitrocontinuous blood stage culture in rhesus monkey,Macaca fascicularisand human red blood cells, as well as the development of various transfection methodologies has resulted in a highly versatile experimental malaria model, further increasing the potential of what was already a very powerful model. The growing evidence thatP. knowlesiis an important human zoonosis in South-East Asia has added relevance to former and future studies of this parasite species.

Long-term thermal two- and three-dimensional analysis of roller compacted concrete dams supported by monitoring verification

2010 ◽  
Vol 37 (4) ◽  
pp. 600-610 ◽  
Author(s):  
Vladan Kuzmanovic ◽  
Ljubodrag Savic ◽  
John Stefanakos
Keyword(s):  
Thermal Analysis ◽  
Boundary Conditions ◽  
Thermal Field ◽  
Numerical Models ◽  
Three Dimensional ◽  
Roller Compacted Concrete ◽  
Rcc Dam ◽  
Field Investigations ◽  
Good Agreement

This paper presents two-dimensional (2D) and three-dimensional (3D) numerical models for unsteady phased thermal analysis of RCC dams. The time evolution of a thermal field has been modeled using the actual dam shape, RCC technology and the adequate description of material properties. Model calibration and verification has been done based on the field investigations of the Platanovryssi dam, the highest RCC dam in Europe. The results of a long-term thermal analysis, with actual initial and boundary conditions, have shown a good agreement with the observed temperatures. The influence of relevant parameters on the thermal field of RCC dams has been analyzed. It is concluded that the 2D model is appropriate for the thermal phased analysis, and that the boundary conditions and the mixture properties are the most influential on the RCC dam thermal behavior.

Impacts of Coal Mining on Groundwater Environment in Northwestern Coal Mine Area

2013 ◽  
Vol 448-453 ◽  
pp. 823-829
Author(s):  
Hao Wang
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Water Cycle ◽  
Numerical Models ◽  
Pumping Test ◽  
Field Investigation ◽  
Groundwater Pumping ◽  
Mine Area ◽  
Groundwater Environment ◽  
Groundwater Flow Field

By conducting field investigation and tests, such as groundwater pumping test and rock mechanics test, and building numerical models to simulate damage of coal mining to aquifers, it was proved that coal mining in some coal mine area caused impacts to groundwater environment, including impact on water cycle, the structure of aquifers, and groundwater flow field, as a result of which some water supply sources in coal mine area become unavailable. In addition, a couple of solutions are presented to mitigate the impacts.

Northeast Atlantic storminess in centennial reanalyses

2021 ◽  
Author(s):  
Oliver Krueger ◽  
Frauke Feser ◽  
Christopher Kadow ◽  
Ralf Weisse
Keyword(s):  
Climate Models ◽  
Numerical Models ◽  
Geostrophic Wind ◽  
Model Systems ◽  
Storm Activity ◽  
Northeast Atlantic ◽  
Wind Speeds ◽  
Long Term Trends ◽  
Storm Index

<p>Global atmospheric reanalyses are commonly applied for the validation of climate models, diagnostic studies, and driving higher resolution numerical models with the emphasis on assessing climate variability and long-term trends. Over recent years, longer reanalyses spanning a period of more than hundred years have become available. In this study, the variability and long-term trends of storm activity is assessed over the northeast Atlantic in modern centennial reanalysis datasets, namely ERA-20cm, ERA-20c, CERA-20c, and the 20CR-reanalysis suite with 20CRv3 being the most recent one. All reanalyses, except from ERA-20cm, assimilate surface pressure observations, whereby ERA-20C and CERA-20c additionally assimilate surface winds. For the assessment, the well-established storm index of higher annual percentiles of geostrophic wind speeds derived from pressure observations at sea level over a relatively densely monitored marine area is used.</p><p>The results indicate that the examined centennial reanalyses are not able to represent long-term trends of storm activity over the northeast Atlantic, particularly in the earlier years of the period examined when compared with the geostrophic wind index based on pressure observations. Moreover, the reanalyses show inconsistent long-term behaviour when compared with each other. Only in the latter half of the 20th century, the variability of reanalysed and observed storminess time series starts to agree with each other. Additionally, 20CRv3, the most recent centennial reanalysis examined, shows markedly improved results with increased uncertainty, albeit multidecadal storminess variability does not match observed values in earlier times before about 1920.</p><p>The behaviour shown by the centennial reanalyses are likely caused by the increasing number of assimilated observations, changes in the observational databases used, and the different underlying numerical model systems. Furthermore, the results derived from the ERA-20cm reanalysis that does not assimilate any pressure or wind observations suggests that the variability and uncertainty of storminess over the northeast Atlantic is high making it difficult to determine storm activity when numerical models are not bound by observations. The results of this study imply and reconfirm previous findings that the assessment of long-term storminess trends and variability in centennial reanalyses remains a rather delicate matter, at least for the northeast Atlantic region.</p>

Comprehensive Evaluation of Rutting of Warm-Mix Asphalt Utilizing Long-Term Pavement Performance Specific Pavement Studies

2020 ◽  
Vol 2674 (7) ◽  
pp. 272-283 ◽  
Author(s):  
Biswajit K. Bairgi ◽  
A.S.M. Asifur Rahman ◽  
Rafiqul A. Tarefder ◽  
Matias M. Mendez Larrain
Keyword(s):  
Comprehensive Evaluation ◽  
Field Investigation ◽  
Warm Mix Asphalt ◽  
Pavement Performance ◽  
Laboratory Evaluation ◽  
Production Temperature ◽  
Wheel Tracking Test ◽  
Modified Binder ◽  
Wheel Tracking

Warm-mix asphalt (WMA) technologies allow binder softening for compaction benefits. Lower production temperature also causes reduced short-term aging in WMA. Considering the long-term implication of the reduced aging and binder softening, WMA is being questioned about its rutting characteristics. As such, this study evaluates different WMA technologies for rutting characteristics in comparison to traditional hot-mix asphalt (HMA) through laboratory and field investigation. The study utilized the long-term pavement performance (LTPP) project in the state of New Mexico called Specific Pavement Study-10 (SPS-10), which was designed to evaluate the WMA performances. The LTPP SPS-10 section includes: (i) control HMA, (ii) foaming, (iii) Evotherm, (iv) Cecabase 1, and (v) Cecabase 2 mixtures. Cecabase 2 mixture consists of a polymer-modified binder (PG 70-28+), whereas other mixtures consist of PG 70-28 binder. The aggregate type, properties, and gradations are the same in all the sections. Laboratory evaluation of rutting was conducted through the Hamburg wheel tracking test. Long-term field rutting was evaluated through Mandli’s pavement profile scanner, a laser-based distress evaluation technology. The study found that WMA with foaming, Evotherm, or Cecabase shows slightly higher rutting compared with the control HMA; however, all the sections satisfied laboratory and field rutting criteria. The use of a polymer-modified binder in WMA significantly improves the rutting characteristics.

scholarly journals High resolution atmospheric reconstruction for Europe 1948–2012: coastDat2

2013 ◽  
Vol 6 (2) ◽  
pp. 779-809 ◽  
Author(s):  
B. Geyer
Keyword(s):  
Climate Model ◽  
Numerical Models ◽  
Regional Climate ◽  
Reanalysis Data ◽  
Data Sets ◽  
Data Set ◽  
Horizontal Grid ◽  
Global Reanalysis ◽  
Marine Climate

Abstract. The coastDat data sets were produced to give a consistent and homogeneous database mainly for assessing weather statistics and long-term changes for Europe, especially in data sparse regions. A sequence of numerical models was employed to reconstruct all aspects of marine climate (such as storms, waves, surges etc.) over many decades. Here, we describe the atmospheric part of coastDat2 (Geyer and Rockel, 2013, doi:10.1594/WDCC/coastDat-2_COSMO-CLM). It consists of a regional climate reconstruction for entire Europe, including Baltic and North Sea and parts of the Atlantic. The simulation was done for 1948 to 2012 with a regional climate model and a horizontal grid size of 0.22° in rotated coordinates. Global reanalysis data were used as forcing and spectral nudging was applied. To meet the demands on the coastDat data set about 70 variables are stored hourly.

Flow-Field Investigation of Two Gas-Sampling Probes

2006 ◽  
Author(s):  
Leiyong Jiang ◽  
Shaji Manipurath ◽  
Gilles Bourque ◽  
Michel Houde
Keyword(s):  
Cooling Water ◽  
Elevated Pressure ◽  
Field Investigation ◽  
Complex Conjugate ◽  
Probe Design ◽  
Wall Region ◽  
Original Design ◽  
Gas Sampling ◽  
Heat Transfers

The flow fields in and around two versions of a water-cooled gas-sampling probe, situated downstream of a gas turbine combustor, were numerically studied in an elevated pressure and temperature environment. The probes are of triple-walled stainless steel assembly, where the gas sample is transported through a centre tube, while preheated and pressurized cooling water flows through two surrounding annuli. Complex conjugate heat transfers amongst the exhaust mixture, cooling water and probe walls were modelled at a selected operating condition. The numerical results indicate over-heating and possible vaporization of water or cavitation in the upstream tip region of the probe with the original design. This is consistent with the evidence of damage observed in these probes from prolonged testing under similar conditions. For the modified probe, the effectiveness of cooling water is much improved, which is confirmed by long-term combustor rig testing. From this investigation, some recommendations for probe design and operation are provided. Moreover, the present study has proved that the numerical simulation is a valuable tool for probe design and trouble-shooting, and to accurately predict conjugate heat transfers in such flows, the laminar sub-layer in the near-wall region should be adequately resolved.

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