A wet/dry point treatment method of FVCOM, part I: stability experiments

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chen, C., Qi, J., Liu, H., Beardsley, R., Lin, H., & Cowles, G. A wet/dry point treatment method of FVCOM, part I: stability experiments. Journal of Marine Science and Engineering, 10(7), (2022): 896, https://doi.org/10.3390/jmse10070896.A 3-dimensional wet/dry point treatment method was developed for the unstructured-grid Finite-Volume Community Ocean Model (FVCOM). Analytical equations were derived to examine discretized errors that occurred during the flooding/drying process by the wet/dry point treatment for the flooding/drying process. Numerical experiments were carried out for an idealized estuary, including the inter-tidal zone. The model results show that if the ratio of internal to external mode time steps (Isplit) is appropriately selected, FVCOM was capable of simulating the flooding/drying process with sufficient accuracy to ensure the mass conservation. The up-bound limit of Isplit was restricted by the bathymetric slope of the inter-tidal zone, external mode time step, horizontal/vertical resolution, and amplitude of tidal forcing at the open boundary, as well as the thickness of the viscous layer specified in the model. Criteria for time steps via these parameters were derived from these experiments, which provide a helpful guide in selectingIsplit for applying FVCOM to realistic geometric estuaries.This research was funded by the Georgia Sea Grant College Program under grant numbers NA26RG0373 and NA66RG0282, the Georgia DNR grants 024409-01 and 026450-01, the NSF Georges Bank/Northwest Atlantic GLOBEC program under grant number NSF-OCE 02-27679, and the SMAST fishery program under the NASA grant number NAG 13-02042

A Modeling Study of Benthic Detritus Flux\u27s Impacts on Heterotrophic Processes in Lake Michigan

Effects of sediment resuspension-induced benthic detrital flux on the heterotrophic part of the microbial food web in Lake Michigan were examined using a three-dimensional (3-D) coupled biological and physical model. The model was driven by the realistic meteorological forcing observed in March 1999. Wind-induced surface wave dynamics were incorporated into the physical model to generate the bottom flux. The model-generated benthic detrital flux was assumed to be proportional to the difference between model-calculated and critical stresses at the bottom. The model results indicate that detrital flux at the bottom was a key factor causing a significant increase of phosphorus and detritus concentrations in the nearshore region of the springtime plume. Inside the plume the sediment-resuspended bottom detritus flux could directly enhance heterotrophic production, while outside the plume, detrital flux from river discharge might have a direct contribution to the high abundance of bacteria and microzooplankton in the nearshore region. Model-data comparison on cross-shore transects near Chicago, Gary, St. Joseph, and Racine suggests that other physical and biological processes may play a comparative role as the bottom detritus flux in terms of the spatial distribution of bacteria and microzoplankton. A more complete microbial food web model needs to be developed to simulate the heterotrophic process in southern Lake Michigan

A finite volume numerical approach for coastal ocean circulation studies : comparisons with finite difference models

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C03018, doi:10.1029/2006JC003485.An unstructured grid, finite volume, three-dimensional (3-D) primitive equation coastal ocean model (FVCOM) has been developed for the study of coastal ocean and estuarine circulation by Chen et al. (2003a). The finite volume method used in this model combines the advantage of finite element methods for geometric flexibility and finite difference methods for simple discrete computation. Currents, temperature, and salinity are computed using an integral form of the equations, which provides a better representation of the conservative laws for mass, momentum, and heat. Detailed comparisons are presented here of FVCOM simulations with analytical solutions and numerical simulations made with two popular finite difference models (the Princeton Ocean Model and Estuarine and Coastal Ocean Model (ECOM-si)) for the following idealized cases: wind-induced long-surface gravity waves in a circular lake, tidal resonance in rectangular and sector channels, freshwater discharge onto the continental shelf with curved and straight coastlines, and the thermal bottom boundary layer over the slope with steep bottom topography. With a better fit to the curvature of the coastline using unstructured nonoverlapping triangle grid cells, FVCOM provides improved numerical accuracy and correctly captures the physics of tide-, wind-, and buoyancy-induced waves and flows in the coastal ocean. This model is suitable for applications to estuaries, continental shelves, and regional basins that feature complex coastlines and bathymetry.This research was supported by the U.S. GLOBEC Northwest Atlantic/Georges Bank program through NSF grants OCE-0234545, OCE-0227679, NOAA grant NA 160P2323, and NSF CoOP grant OCE-0196543 to C. Chen and NSF OCE-0227679 and the WHOI Smith Chair to R. C. Beardsley. H. Huang and Q. Xu were supported by Chen’s Georgia and South Carolina Sea Grant awards NA06RG0029 and NA960P0113. G. Cowles was supported by the SMAST fishery program through NOAA grants DOC/NOAA/NA04NMF4720332 and DOC/NOAA/NA05NMF4721131

Rapid diagnosis of new and relapse tuberculosis by quantification of a circulating antigen in HIV-infected adults in the Greater Houston metropolitan area

Abstract Background HIV-associated immune defects inhibit tuberculosis (TB) diagnosis, promote development of extrapulmonary TB and paucibacillary pulmonary TB cases with atypical radiographic features, and increase TB relapse rates. We therefore assessed the diagnostic performance of a novel assay that directly quantitates serum levels of the Mycobacterium tuberculosis (Mtb) virulence factor 10-kDa culture filtrate protein (CFP-10) to overcome limitations associated with detecting Mtb bacilli in sputum or tissue biopsies. Methods This study analyzed HIV-positive adults enrolled in a large, population-based TB screening and surveillance project, the Houston Tuberculosis Initiative, between October 1995 and September 2004, and assigned case designations using standardized criteria. Serum samples were trypsin-digested and immunoprecipitated for an Mtb-specific peptide of CFP-10 that was quantified by liquid chromatography-mass spectrometry for rapid and sensitive TB diagnosis. Results Among the 1053 enrolled patients, 110 met all inclusion criteria; they included 60 tuberculosis cases (12 culture-negative TB), including 9 relapse TB cases, and 50 non-TB controls, including 15 cases with history of TB. Serum CFP-10 levels diagnosed 89.6% (77.3–96.5) and 66.7% (34.9–90.1) of culture-positive and culture-negative TB cases, respectively, and exhibited 88% (75.7–95.5) diagnostic specificity in all non-TB controls. Serum antigen detection and culture, respectively, identified 85% (73.4–92.9) and 80.0% (67.3–88.8) of all 60 TB cases. Conclusions Quantitation of the Mtb virulence factor CFP-10 in serum samples of HIV-infected subjects diagnosed active TB cases with high sensitivity and specificity and detected cases missed by the gold standard of Mtb culture. These results suggest that serum CFP-10 quantitation holds great promise for the rapid diagnosis of suspected TB cases in patients who are HIV-infected

Durability of the Bond between CFRP and Concrete Exposed to Thermal Cycles

The bond between carbon fiber reinforced polymer (CFRP) and concrete is significantly and adversely affected by thermal cycles in air and water. In the present study, the effects of thermal cycles in air or water on the bond performance between CFRP and concrete were examined. A single-lap shear test was adopted to evaluate the performance of the CFRP⁻concrete bond. A number of 270 thermal cycles in air increased the interfacial fracture energy of the CFRP plate⁻ and CFRP sheet⁻concrete by 35% and 20%, respectively while 270 thermal cycles in water reduced the interfacial fracture energy of the CFRP plate⁻ and CFRP sheet⁻concrete by 9% and 46%, respectively. Thermal cycles in water caused the failure mode to change from concrete cohesive failure to primer⁻concrete interfacial debonding. The failure modes of CFRP⁻concrete exposed to thermal cycles in air still occurred in concrete. A reduction factor for the CFRP⁻concrete structure for thermal cycles in water was proposed

Improved delayed detached eddy simulation of supersonic combustion fueled by liquid kerosene

The purpose of this study is to quantitatively investigate the influence of diffusion characteristics and equivalence ratios (ERs) of gaseous/liquid kerosene on transient combustions in a three-dimensional cavity-based scramjet combustor using Improved Delayed Detached Eddy Simulation (IDDES) with a 19 species and 54 reactions kerosene/air mechanism. Additionally, the similarities and differences between gaseous and liquid kerosene supersonic combustion are identified based on the pressure, mixture fraction, temperature, and heat release rate distributions. The findings indicated that the injection velocity of liquid kerosene is an order of magnitude lower than that of gaseous kerosene; however, the residence time of liquid kerosene in the cavity was amplified by two orders of magnitude. The results also highlighted the substantial differences in the reaction heat release position between gaseous and liquid kerosene combustion. For a combustion process of liquid kerosene at an ER of 0.215, there is no obvious boundary layer separation in the isolator. The combustion process is controlled by the mixing efficiency of the shear layer, and the mode of combustion is cavity shear-layer stabilized combustion. When the ERs are 0.27 and 0.43, the flame propagates upstream of the cavity and forms boundary layer separation and oblique shock waves. Then, the combustion process is controlled by the fuel transportation in the cavity recirculation zone, and the mode of combustion is the cavity recirculation-zone stabilized combustion

Next generation ocean dynamical core roadmap project: final report. Report for the NERC Ocean Roadmap exercise

This document should be read in conjunction with the “Next Generation Ocean Dynamical Core Roadmap Project: Summary and Recommendations” document, which provides a summary of the present “Final Report”, and a Roadmap for ways forward for UK ocean modelling over the next 5-15 years. It describes two complementary ways forward: first is the incremental evolution of the NEMO model, and second a new modelling initiative drawing on the GungHo project

Porosity, Pore Size Distribution and Chloride Permeability of Shotcrete Modified with Nano Particles at Early Age

Nano particles have been found to be effective in enhancing many properties of regular concretes. However, there is little information on the effect of nano particles on shotcrete. In fact, if similar positive effect of nano particles can also appear in shotcrete, they will greatly benefit the wide application of shotcrete in more and more repair and strengthening of structures in civil engineering, especially in corrosive environments. In this study, through experiments on 70 specimens, the effects of nano SiO2, CaCO3 and Al2O3 particles on the early-age porosity, pore size distribution, compressive strength and chloride permeability of shotcrete were investigated.Test results indicated that nano SiO2 particles significantly increased the compressive strength and chloride penetration resistance; nano Al2O3 and CaCO3 particles had slight enhancing effect on the compressive strength; nano CaCO3 particles were most effective in promoting the chloride penetration resistance of shotcrete. As a conclusion, nano SiO2 particles were recommended when both early age compressive strength and chloride penetration resistance were crucial, and nano CaCO3 particles were recommended when only chloride penetration resistance was concerned for their high cost-effectiveness

Next generation ocean dynamical core roadmap project: summary and recommendations. Report for the NERC Ocean Roadmap exercise

This document provides a summary of the final report of the Next Generation Ocean Dynamical Core Roadmap Project and recommendations for the way forward: essentially it provides the ‘road map’. To be read alongside the final report, it describes two complementary ways forward for ocean modelling in the UK. First is the incremental evolution of the NEMO model, and second a new modelling initiative drawing on the GungHo project; we make the assumption that the current NEMO code base has a finite competitive life time, and over the course of this review period will ‘lose its edge’ and become increasing inefficient and problematic to use. The key question is then whether this existing code base can be re-factored for future computer architectures or whether a new approach is needed. In this consideration, it is vital to make the distinction between the NEMO code and the NEMO consortium; the latter is seen as a crucial element in UK ocean modelling capability throughout the review period. The Ocean Road Map project has identified two concurrent pathways for ocean model development in the UK: 1. Develop NEMO for global, shelf sea and ‘global coastal ocean’ applications. 2. Develop an ocean model within the GungHo framework. This document largely focuses on the justification for (2), as being the new direction. Further details on (1) for the short- medium term can be found in section 2 and 3 of the final report