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Increased intensity and frequency of floods raise concerns about the release and transport of contaminated soil and sediment to and from rivers and streams. To model these processes during flooding events, we developed an External Coupler in Python to link the Hydrologic Engineering Center‐River Analysis System (HEC‐RAS) 2D hydrodynamic model to the Water Quality Analysis Simulation Program (WASP). Accurate data transfer from a hydrodynamic model to a water quality model is critical. Our test results showed the External Coupler successfully linked HEC‐RAS and WASP and addressed technical challenges in aggregating flow data and conserving mass during the flood event. We ran the coupled models for a 100‐year flood event to calculate flood‐induced transport of sediment‐associated arsenic in Woodbridge Creek, NJ. Change in surface sediment and arsenic at the end of 48‐h flood simulation ranged from a net loss of 13.5 cm to a net gain of 11.6 cm, and 16.2 to 2.9 mg/kg, respectively, per model segment, which demonstrates the capability of the coupled model for simulating sediment and contaminant transport in flood.

Defne, Z.; Spitz, F.J.; DePaul, V., and Wool, T.A., 2017. Toward a comprehensive water-quality modeling of Barnegat Bay: Development of ROMS to WASP coupler. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay-Little Egg Harbor, New Jersey. The Regional Ocean Modeling System (ROMS) has been coupled with the Water Quality Analysis Simulation Program (WASP) to be used in a comprehensive analysis of water quality in Barnegat Bay, New Jersey. The coupler can spatially aggregate hydrodynamic information in ROMS cells into larger WASP segments. It can also be used to resample ROMS output at a finer temporal scale to meet WASP time-stepping requirements. The coupler aggregates flow components, temperature, and salinity in ROMS output for input to WASP via a hydrodynamic linkage file. The coupler was tested initially with idealized cases designed to verify the water mass balance and conservation of constituent mass using one-to-one and one-to-many connectivity options between segments. A realistic example from the Toms River embayment, a subdomain of Barnegat Bay, was used to demonstrate the functionality of the coupling. A WASP eutrophication model accounting for dissolved oxygen (DO), nitrogen, and constant phytoplankton concentrations was applied to explore the distribution and trends in DO and nitrogen in the embayment for the period of July–August 2012. Results of DO modeling indicate satisfactory agreement with measurements collected at in-bay stations and also indicate that this coupled approach, despite substantial differences in spatiotemporal discretization between the models, provides adequate predictive capabilities.

This article presents a design of a novel swimming mechanism based on a linkage mechanism. The generated motions of the proposed mechanism mimic the purely aquatic locomotion of frogs such as Xenopus laevis (X. laevis) , including both the motions of the hind legs and the webbed foot. A six-bar linkage mechanism is employed in this study combing with a spatial linkage mechanism to simplify the overall mechanism. Attributes to the optimal design, the number of Degrees of Actuations (DoA) reduces to two in each hindlimb, which realizes miniaturization in the current study. Kinematic analysis is conducted to analyze the locomotion of the spatial mechanism. The hydrodynamic model based on the blade element theory is established to estimate the swimming performance of the designed mechanism. The peak thrust (approximately 0.2  N ) is dramatically larger than the minimum drag (−0.023  N ) observed in the experiment which increases the efficiency of the prototype’s swimming.

Cellulose nanofibers (CNFs) are plant-derived nanomaterials with promising potential for sustainable applications. However, their aqueous dispersions are susceptible to microbial contamination, necessitating sterilization for long-term storage and applications in food, cosmetics, and toxicity testing. Although gamma irradiation effectively inactivates microorganisms, it can alter the physical and chemical properties of cellulose, especially at high doses. In this study, we evaluated the effects of low-dose gamma irradiation (1–25 kilo Grays, kGy) on four types of commercially available CNFs. The 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized CNFs (TO-CNFs) subjected to gamma irradiation showed decreased molecular weight, fiber length, hydrodynamic particle size, and glycosidic bond-related infrared (IR) peak intensity, along with increased reducing ends and C=O stretching-related IR peak areas, indicating glycosidic bond cleavage and fiber shortening. Similar changes were observed in phosphorylated CNFs (P-CNFs) and aqueous counter collision CNFs (ACC–CNFs). In contrast, mechanically fibrillated CNFs (MF-CNFs) exhibited minimal changes. The viscosity and dynamic modulus of TO-CNFs and P-CNFs decreased, likely due to degradation, whereas these properties increased in ACC–CNFs and MF-CNFs, possibly due to cross-linking effects. Given the broad distributions of molecular weight and fiber length in native CNFs, the effect of gamma irradiation at a few kGy appeared to be minimal. Our findings offer a valuable reference for determining optimal gamma radiation doses for sterilization while preserving the CNF properties.

Cycloidal propellers constitute a specialized category of underwater propulsion devices, widely employed in vehicles requiring exceptional maneuverability. The parameters of the blade-driving mechanism directly impact the propeller performance. Hence, the effect of variations in the geometric parameters of the blade-driving mechanism on the hydrodynamic performance of cycloidal propellers must be investigated. In this study, a specific set of four-bar and mixed four-bar/five-bar mechanisms are taken as examples, and the effect of linkage-length variations on the hydrodynamic performance of cycloidal propellers was analyzed using numerical simulation methods. First, we established a physical model of the cycloidal propeller, and then derived the relationship between blade-rotation and revolution angles. Subsequently, by solving the Navier–Stokes equations and employing computational fluid dynamics simulations based on viscosity, an analysis is conducted to reveal the trends in the impact of different linkage-length combinations on the hydrodynamic performance of the cycloidal propeller. Finally, the outcomes of the numerical simulations are interpreted using the wing element theory. In similar blade-driving mechanisms, the effects of varying linkage lengths on propeller hydrodynamic performance are determined through alterations in the blade rotation angle range and equilibrium position. An increase in the range of the blade-rotation angle significantly enhances the hydrodynamic performance of the cycloidal propeller. This research employs a more realistic auto-propulsion mode for numerical simulations, establishing a mapping relationship between the blade-driving mechanism and hydrodynamic performance of the cycloidal propeller, while analyzing the underlying influencing mechanisms. Furthermore, crucial numerical simulations and theoretical foundations are employed for designing the four-bar and mixed four-bar/five-bar mechanism cycloidal propellers. The findings of this study could also be used in similar cycloidal propellers with multilinkage mechanism.

The outdoor wind environment and thermal environment are important factors affecting human comfort in cold winter conditions. The spatial layout of plant communities plays an important role in improving the outdoor microclimate and improving outdoor comfort. In order to explore the positive effect of plant layout on outdoor comfort in cold winter, this study took Xuzhou Tangfang Middle School with typical layout characteristics as the research object. In this study, we simulated the wind environment of these models using computational fluid dynamics (CFD) methods and the outdoor thermal environment using Ecotect (2011), and used linear regression and one-way ANOVA for mathematical statistics. The wind environment and Universal Thermal Climate Index (UTCI) of campus outdoor activities distributed in different spaces were analyzed and evaluated. The research results showed that the superposition of wind and thermal environments identified the key areas of the campus (cross-flow area and corner flow area) and showed a negative correlation. The staggered layout of the three plant combinations increases the wind prevention efficiency by 39.4%. At the same time, this study established the linkage mechanism of campus plant layout, environmental microclimate, and activity area comfort, which effectively improved outdoor human comfort in cold winter. This research can provide a reference for the remediation and improvement of the comfort of the same type of campus, and also provide data support and reference significance for the research on the outdoor pedestrian environment in winter.

Morphometry of oxbow lakes is widely used as a tool for knocking the evolutionary history of geomorphology and hydraulics of the region concerned. Oxbow lakes are the treasury of abundant geomorphological records of yesteryears which could serve as important keys to the past fluvial environment. But in terms of morphometric magnitudes, today’s oxbow lakes differ significantly from the then river from which they were originated. That is why identifying the parent river and gauging the dimensions of past morphology of the parent river of the oxbow lakes is an important issue of fluvial geomorphology. That is why the present paper searches parent–daughter umbilical linkage between an oxbow lake and adjacent river and designs quantitative measures to find out the degree of similitude between an oxbow lake and adjacent rivers. We processed planimetric morphological variables (distance, width, amplitude, the radius of curvature and orientation angle) of 126 oxbow lakes and adjacent 13 rivers using statistical and mathematical tools. We found that there is a strong morphometric association between oxbow lakes and their parent river. Finally, we conclude that morphometrics of an oxbow lake can successfully be used for identifying its parent river. So, we suggested five indices to ascertain the degree of similitude for confirming the parent–daughter umbilical linkage between oxbow lake and adjacent river.

As the stratigraphic record is neither homogenous nor isotropic, a fundamental challenge in sedimentary geology is characterizing and predicting the nature of variability. Although many nearshore to shallow-marine siliciclastic depositional systems have been grouped into wave-dominated and tide-dominated classes, many facies models of carbonate systems have not recognized or applied this distinction. To fill this gap, the purpose of this study is to compare and contrast the hydrodynamic processes, sedimentology, geomorphology, and stratigraphy of an oolitic tide-dominated shoal complex and an oolitic wave-dominated shoreline system from the same area (Crooked–Acklins Platform, southern Bahamas). Field, petrographic, granulometric, remote-sensing, and hydrodynamic data illustrate marked contrasts between the two end members. The wave-dominated shoreface system near French Wells on the leeward margin is influenced by small (H s <30 cm) waves and only weak, wave-driven currents (<15 cm/s, net southward flow); the passage of Hurricane Irene (in 2011) had only a local impact on the shoreface. The low-energy setting favors generation and alongshore transport of ooids and peloids of fine- to medium-sized sand, and has facilitated nearly 1 km of shoreface progradation, forming geomorphic bodies with margin-parallel geometry. The stratigraphic record of the area includes a coarsening- and shoaling-upward succession. In contrast, the ~7-km-wide, tide-dominated shoal on the southwestern margin is dominated by vigorous tidal currents (in excess of 50 cm/s, and reversing twice daily). These currents generate margin-normal bars and channels consisting of oolitically coated grains of medium to coarse sand size. Stratigraphically, above a basal clast-rich deposit, sediment size and sorting vary across the shoal. The open-ocean and the platformward flanks of the shoal, most impacted by tide and wave energy, include the cleanest oolitic sand, with fines accumulating in the stabilized shoal interior. Overall, the oolitic shoal aggraded and expanded platformward over bioturbated peloid–ooid sand. These results reveal how sediment, geomorphology, and stratigraphy differ between tide- and wave-dominated end members, patterns broadly analogous to several ancient examples. These data collectively illustrate the processes that create multi-scale linkages among stratigraphic patterns, geological facies bodies, and granulometry (e.g., depositional porosity and permeability). These linkages provide information that could be used to predict sedimentological and geomorphical trends in ancient analogues.

Contaminants released by wind-induced sediment resuspension could influence the water quality in shallow lakes. This study aims to reveal the quantitative relationship between wind speed (v) and sediment resuspension rate (r) in Meiliang Bay of Lake Taihu. The study was conducted in three steps. First, the in situ wind speed and current velocity were measured over a period of 2 days in Meiliang Bay to establish the relationship between wind and hydrodynamic conditions; second, an indoor experiment was conducted in a cylindrical simulator with sediment from the study area to determine sediment resuspension rates under different hydrodynamic conditions; and third, linkages between sediment resuspension and wind were determined. The average sediment resuspension rate was highly correlated with the wind speed (R2 = 0.99), and was expressed by r = 20.72v2.034 at wind speeds in the range of 0–14 m/s. The critical wind speed for sediment resuspension is about 7 m/s. Under these conditions, the average resuspension rate could reach 1,000 g/(m2d), with a total phosphorus release rate of 1.1 g/(m2d) and a total nitrogen release rate of 18.1 g/(m2d).

We present algorithms and tools we developed to automatically link an overland flow model to a hydrodynamic water quality model with different spatial and temporal discretizations. These tools run the linked models which provide a stochastic simulation frame. We also briefly present the tools and algorithms we developed to facilitate and analyze stochastic simulations of the linked models. We demonstrate the algorithms by linking the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model for overland flow with the CE‐QUAL‐W2 model for water quality and reservoir hydrodynamics. GSSHA uses a two‐dimensional horizontal grid while CE‐QUAL‐W2 uses a two‐dimensional vertical grid. We implemented the algorithms and tools in the Watershed Modeling System (WMS) which allows modelers to easily create and use models. The algorithms are general and could be used for other models. Our tools create and analyze stochastic simulations to help understand uncertainty in the model application. While a number of examples of linked models exist, the ability to perform automatic, unassisted linking is a step forward and provides the framework to easily implement stochastic modeling studies.