239 research outputs found

    Development of an unstructured grid, finite volume eutrophication model for the shallow water coastal bay: Application in the Lynnhaven River Inlet system

    Get PDF
    The shallow water region is an important portion of the estuarine and coastal waters, since it encompasses the entire land-water margin as the buffer zone and supports one of the most productive ecosystems. When light can penetrate to the sediment, it triggers the benthic microalgae community to perform photosynthesis, resulting in a benthic-pelagic exchange flux different from that of the deeper water. This study utilized the laboratory-measured benthic flux, and a suite of well-calibrated numerical models to examine the eutrophication process in the Lynnhaven River Inlet system with special emphasis on: the role played by benthic microalgae, and nutrient budgets (sources, sinks, and pathways) of the system. An unstructured grid hydrodynamic model UnTRIM developed for the shallow water environment was applied to the Lynnhaven to quantify the transport time scale and as the input for the water quality model. Based on the skill assessment result, it was clear that the presence of benthic microalgae is indispensable for an accurate and realistic calibration of the water quality model. Analysis of field samples in the laboratory experiments demonstrated that benthic microalgae performed photosynthesis under light conditions in surficial sediments, resulting in the net uptake of nutrients and the release of oxygen both to the overlying water column and down to the sediment. Based on the results of annual nutrient budgets, it was shown that the major external source for nitrogen and phosphorus was from nonpoint source loadings. There were three comparable sinks: export to the Bay, burial in the deep sediment, and ditrification in the case of nitrogen. One of the major pathways for nitrogen and phosphorus was the internal recycling. The regenerated dissolved nutrients that were recycled in the water column were more than two times larger than the current total nutrient external loadings. Sensitivity tests showed that, due to their retention capacity, benthic microalgae\u27s presence could decrease the overall export to the Bay, enhance the internal recycling, and increase the denitrification rate in the sediment

    HurriCast: An Automatic Framework Using Machine Learning and Statistical Modeling for Hurricane Forecasting

    Full text link
    Hurricanes present major challenges in the U.S. due to their devastating impacts. Mitigating these risks is important, and the insurance industry is central in this effort, using intricate statistical models for risk assessment. However, these models often neglect key temporal and spatial hurricane patterns and are limited by data scarcity. This study introduces a refined approach combining the ARIMA model and K-MEANS to better capture hurricane trends, and an Autoencoder for enhanced hurricane simulations. Our experiments show that this hybrid methodology effectively simulate historical hurricane behaviors while providing detailed projections of potential future trajectories and intensities. Moreover, by leveraging a comprehensive yet selective dataset, our simulations enrich the current understanding of hurricane patterns and offer actionable insights for risk management strategies.Comment: This paper includes 7 pages and 8 figures. And we submitted it up to the SC23 workshop. This is only a preprintin

    Transmission Routes of the Microbiome and Resistome from Manure to Soil and Lettuce

    Get PDF
    The land application of animal manure can introduce manure microbiome and resistome to croplands where food crops are grown. The objective of this study was to characterize the microbiome and resistome on and in the leaves of lettuce grown in manured soil and identify the main transmission routes of microbes and antibiotic resistance genes (ARGs) from soil to the episphere and endosphere of lettuce. Shotgun metagenomic results show that manure application significantly altered the composition of the microbiome and resistome of surface soil. SourceTracker analyses indicate that manure and original soil were the main source of the microbiome and resistome of the surface soil and rhizosphere soil, respectively. Manure application altered the microbiome and resistome in the episphere of lettuce (ADONIS p \u3c 0.05), and surface soil accounted for ~81% of the microbes and ~62% of the ARGs in episphere. Manure application had limited impacts on the microbiome and resistome in the endosphere (ADONIS p \u3e 0.05). Our results show that manure-borne microbes and ARGs reached the episphere primarily through surface soil and some epiphytic microbes and ARGs further entered the endosphere. Our findings can inform the development of pre- and postharvest practices to minimize the transmission of manure-borne resistome from food crops to consumers

    Experimenting adaptive services in sea-cloud innovation environment

    Get PDF
    Most of existing network testbeds can only support the experimentation of L2~L4 forwarding protocols, leaving the evaluation of L4~L7 applications still a tremendous challenge. This paper pioneers to present the design of sea-cloud innovation environment (SCIE) based on the software defined networking (SDN) and network functions virtualization (NFV) paradigms to support adaptive service-oriented experimentation, where the virtualized network functions (VNFs) can be implemented or deimplemented dynamically on network devices according to ondemand requirements. The experimentation is running to form an adaptive chain of network functions, which can be achieved by the protocol oblivious forwarding (POF) via user-defined fields and generic flow instruction set to forward the data to appropriate devices with VNFs. In SCIE, we demonstrate the experimentation of DPI service with on-demand requirement of security check

    Spatial-Temporal Variability of Soil Organic Matter in Urban Fringe over 30 Years: A Case Study in Northeast China.

    Get PDF
    The study on soil organic matter (SOM) is of great importance to regional cultivated land use and protection. Based on data collected via continuous and high-density soil samples (0-20 cm) and socio-economic data collected from household survey and local bureau of statistics, this study employs geostatistics and economic statistical methods to investigate the spatial-temporal variation of SOM contents during 1980-2010 in the urban fringe of Sujiatun district in Shenyang City, China. We find that: (1) as to temporal variation, SOM contents in the study sites decreased from 30.88 g/kg in 1980 to 22.63 g/kg in 2000. It further declined to 20.07 g/kg in 2010; (2) in terms of spatial variation, the closer to city center, the more decline of SOM contents. Contrarily, SOM contents could even rise in outer suburb area; and (3) SOM content variation may be closely related to human factors such as farmers’ land use target and behaviour including inputs of chemical and organic fertilizers, types of crops and etc. These findings are conductive to grasp the overall trend of SOM variation and the influence of farmers’ land use behaviour on it. Furthermore, they could provide support for policymakers to agricultural planning and land use monitoring, which consequently aids the improvement of soil quality and food production in the urban fringe areas

    Optimal Choices for the E-Tailer with Inventory Rationing, Hybrid Channel Strategies, and Service Level Constraint under Multiperiod Environments

    Get PDF
    This paper investigates optimal choices for the e-tailer with inventory rationing, hybrid channel strategies, and service level constraint under multiperiod environment. Based on different operational conditions, five mathematical models are proposed for the e-tailer who faces two types of fuzzy demand and a framework is designed to illustrate the e-tailer’s operation in different models. This paper presents the advantages of inventory rationing and hybrid channel strategies and analyzes the influences of channel differences variability on optimal choices for the e-tailer, where the channel differences include margin difference of priority and margin difference of channel. Through computer simulation, the optimal choices for the e-tailer under different multiperiod environments are obtained, and the influences of margin difference of priority and margin difference of channel on the e-tailer’s optimal choices are also examined. Experiment results show that the pure-play drop shipping model and the hybrid channel with inventory rationing model are the optimal choices for the e-tailer; these findings have valuable guiding significance for the e-tailer to make optimal tactical decisions under multiperiod environment

    A Kernel-space POF virtual switch

    Get PDF
    Protocol Oblivious Forwarding (POF) aims at providing a standard southbound interface for sustainable Software Defined Networking (SDN) evolvement. It overcomes the limitations of popular Open Flow protocols (an existing widely-adopted southbound interface), through the enhancement of SDN forwarding plane. This paper pioneers the design and implementation of a Kernel-space POF Virtual Switch (K_POFVS) on Linux platform. K_POFVS can improve the packet processing speed, through fast packet forwarding and the capability of adding/deleting/modifying protocol fields in kernel space. In addition, it is able to enhance flow table matching speed, by separating the mask table (consisting of flow entry masks used to figure out the matching field) and the flow table under a caching mechanism. Furthermore, K_POFVS can achieve efficient communication between the kernel space and the user space, via extending the Netlink communication between them. Experimental results show that K_POFVS can provide much better performance than existing user-space POF virtual switches, in terms of packet forwarding delay, packet processing delay and packet transmission rateThis work is partially supported by the National Program on Key Basic Research Project of China (973 Program) under Grant No. 2012CB315803, the Strategic Priority Research Program of the Chinese Academy of Sciences under grant No. XDA06010306, the National Natural Science Foundation of China under Grant No. 61303241, and the University of Exeter’s Innovation Platform – Link Fund under Award No. LF207

    Facile synthesis of di-mannitol adipate ester-based zinc metal alkoxide as a bi-functional additive for poly(vinyl chloride)

    Get PDF
    A new di-mannitol adipate ester-based zinc metal alkoxide (DMAE-Zn) was synthesized as a bi-functional poly(vinyl chloride) (PVC) thermal stabilizer for the first time. The materials were characterized with Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterization results confirmed the formation of Zn–O bonds in DMAE-Zn, and confirmed that DMAE-Zn had a high decomposition temperature and a low melting point. The thermal stability of DMAE-Zn on PVC also was tested by a conductivity test, a thermal aging test, and a UV-visible spectroscopy (UV-VIS) test. PVC stabilized by DMAE-Zn had a good initial color and excellent long-term stability. UV-VIS also showed that the conjugated structure in PVC stabilized by DMAE-Zn was almost all of the triene, suggesting that the addition of DMAE-Zn would suppress the formation of conjugated structures above tetraene. The dynamic processing performance of PVC samples tested by torque rheometer indicated that, having a good compatibility with PVC chains in the amorphous regions, DMAE-Zn contributed a good plasticizing effect to PVC. DMAE-Zn thus effectively demonstrates bi-functional roles, e.g., thermal stabilizers and plasticizers to PVC. Furthermore, FT-IR, a HCl absorption capacity test, and a complex ZnCl2 test were also used to verify the thermal stability mechanism of DMAE-Zn for PVC
    • …
    corecore