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Modeling ocean wave propagation under sea ice covers

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Acta Mechanica Sinica 2015年第1期31卷 1-15页

作者： Xin Zhao hayley H. Shen Sukun Cheng Department of Civil and Environmental Engineering Clarkson University

Operational ocean wave models need to work globally, yet current ocean wave models can only treat ice covered regions crudely. The purpose of this paper is to provide a brief overview of ice effects on wave propagation and different research methodology used in studying these effects. Based on its proximity to land or sea, sea ice can be classified as： landfast ice zone, shear zone, and the marginal ice zone. All ice covers attenuate wave energy. Only long swells can penetrate deep into an ice cover. Being closest to open water, wave propagation in the marginal ice zone is the most complex to model. The physical appearance of sea ice in the marginal ice zone varies. Grease ice, pancake ice, brash ice, floe aggregates, and continuous ice sheet may be found in this zone at different times and locations. These types of ice are formed under different thermalmechanical forcing. There are three classic models that describe wave propagation through an idealized ice cover： mass loading, thin elastic plate, and viscous layer models. From physi cal arguments we may conjecture that mass loading model is suitable for disjoint aggregates of ice floes much smaller than the wavelength, thin elastic plate model is suitable for a con tinuous ice sheet, and the viscous layer model is suitable for grease ice. For different sea ice types we may need different wave ice interaction models. A recently proposed viscoelas tic model is able to synthesize all three classic models into one. Under suitable limiting conditions it converges to the three previous models. The complete theoretical framework for evaluating wave propagation through various ice covers need to be implemented in the operational ocean wave models. In this review, we introduce the sea ice types, previous wave ice interaction models, wave attenuation mechanisms,the methods to calculate wave reflection and transmission between different ice covers, and the effect of ice floe breaking on shaping the sea ice morphology. Labora

关键词： Ocean waves Sea ice Cryospheric change

Characteristics of temporal-spatial parameters in quasi-solid-fluid phase transition of granular materials

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Chinese Science Bulletin 2006年第6期51卷 646-654页

作者： JI Shunying SHEN H hayley State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 China Department of Civil and Environmental Engineering Clarkson University Potsdam NY 13699-5710 USA

The quasi-solid-fluid phase transition of granular materials is closely related to the shear rate and solid concentration in addition to their intrinsic properties. The contact duration and the coordination number are two important temporal-spatial parame-ters to describe the granular interaction in phase transition. In this study, characteristics of the contact duration and the coordination number associated with the transition processes are determined using a 3D discrete element model under different shear rates and concentrations. The resulting macroscopic stress and strain-rate relations are discussed. The temporal and spatial parameters provide a linkage between the macroscopic constitutive law and inter- particle micromechanics.

关键词：颗粒材料粒状流动力学准固-液相变时空参数

Granular pressure–temperature relation during regime change in a simple shear state

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Theoretical & Applied Mechanics Letters 2013年第2期3卷 21-24页

作者： hayley Shen Department of Civil and Environmental Engineering Clarkson University

In a recent study, a regime chart was established for sheared granular systems. For a soft particle system under simple shear, the internal stress showed a range of rate dependency. As the particle concentration increased, the system transitioned from a kinetic gas to a plastic solid. This transition was gradual for low stiffness systems but became more abrupt as the stiffness increased. In this study, the relationship between the granular temperature and pressure is investigated for the same system of particles. The granular temperature is defined as the average kinetic energy per unit volume and the pressure is defined as the trace of the stress tensor. It is found that this pressure-temperature （P-T） curve depicts a sharp turn when the system moves away from the kinetic gas regime. However, no signature is found in the P-T relationship in other regimes.

关键词： granular materials regime change pressure temperature

Disease-associated oligodendrocyte signatures in neurodegenerative disease:the known and unknown

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Neural Regeneration Research 2023年第10期18卷 2192-2193页

作者： Kristen H.Schuster hayley S.McLoughlin Department of Neurology University of MichiganAnn ArborMIUSA

Oligodendrocytes are one of the most abundant cell types in the central nervous system(CNS)and act in close contact with neurons to assist with their cellular function and health(Kuhn et al.,2019).Oligodendrocytes play particular roles in rapid nerve impulse conduction through the wrapping of their myelinating projections a round a nerve axon,as well as by offering trophic and metabolic support for the high energy expenditure of ***。

关键词： cytes degenerative

Spatial and temporal patterns of sarcoptic mange in wombats using the citizen science tool,WomSAT

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Integrative Zoology 2024年第3期19卷 387-399页

作者： Sujatha MAYADUNNAGE hayley Jade STANNARD Peter WEST Julie M.OLD School of Science Western Sydney UniversityHawkesburyNSWAustralia School of Agricultural Environmental and Veterinary SciencesCharles Sturt UniversityWagga WaggaNSWAustralia Department of Primary Industries Orange Agricultural InstituteOrangeNSWAustralia

There is currently limited information regarding the levels of infection and distribution of sarcoptic mange in the wombat population throughout *** analyzed cases of sarcoptic mange in bare-nosed wombats reported into WomSAT,a website and mobile phone application where citizen scientists can upload sightings of wombats,burrows,and sarcoptic mange *** used Maxent software to predict locations and the environmental factors associated with sarcoptic mange occurrence in bare-nosed wombats.A total of 1379 sarcoptic mange-infected and 3043 non-sarcoptic mange-infected wombats were reported by 674 and 841 citizen scientists,*** all the wombats reported to WomSAT from 2015 to 2019,31.2%were infected with sarcoptic *** mange in bare-nosed wombats was reported in 502 suburbs across four *** South Wales had the highest number of sarcoptic mange cases reported to *** was no statistically significant seasonal variation of sarcoptic mange levels in bare-nosed *** model showed that Euclidean distance to urban areas was the highest contributing factor for sarcoptic mange *** distance to urban areas decreased,the suitability for sarcoptic mange *** precipitation was the next contributing factor in the model,with higher rainfall of 400–700 mm correlating to an increase in sarcoptic mange *** the data collected to date have provided the largest-scale contemporary distribution of sarcoptic mange in wombats,data should continue to be collected by citizen scientists as it is an easy and low-cost method of collecting data over large *** suggest targeting the identified hotspot areas and more site-specific studies for studying and mitigating sarcoptic mange in bare-nosed wombats.

关键词： bare-nosed wombats habitat suitability Maxent modeling

A viscoelastic-plastic constitutive model with Mohr-Coulomb yielding criterion for sea ice dynamics

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Acta Oceanologica Sinica 2005年第4期24卷 54-65页

作者： JI Shunying SHEN Hung Tao WANG Zhilian SHEN H hayley YUE Qianjin State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 China Department of Civil and Environmental Engineering Clarkson University Potsdam New York 13699-5710 USA

A new viscoelastic-plastic （VEP） constitutive model for sea ice dynamics was developed based on continuum mechanics. This model consists of four components： Kelvin-Vogit viscoelastic model, Mohr-Coulomb yielding criterion, associated normality flow rule for plastic rehololgy, and hydrostatic pressure. The numerical simulations for ice motion in an idealized rectangular basin were made using smoothed particle hydrodynamics （SPH） method, and compared with the analytical solution as well as those based on the modified viscous plastic（VP） model and static ice jam theory. These simulations show that the new VEP model can simulate ice dynamics accurately. The new constitutive model was further applied to simulate ice dynamics of the Bohai Sea and compared with the traditional VP, and modified VP models. The results of the VEP model are compared better with the satellite remote images, and the simulated ice conditions in the JZ20-2 oil platform area were more reasonable.

关键词： sea ice dynamics constitutive model viscous plasticity viscoelastic-plastic model Molar-Coulomb criterion

Scale dependence of direct shear tests

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Chinese Science Bulletin 2009年第23期54卷 4337-4348页

作者： ZHOU Qiang SHEN hayley H HELENBROOK Brian T ZHANG HongWu Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China Department of Civil and Environmental Engineering Clarkson University Potsdam NY 13699-5710 USA Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam NY 13699-5725 USA

Direct shear test has been widely used to measure the shear strength of soils and other particulate materials in industry because of its simplicity. However, the results can be dependent on the specimen size. The ASTM (American Society for Testing and Materials) publications suggest that for testing soils the shear box should be at least ten times the diameter of the largest particle and the height of the box should be no more than half of its diameter. These guidelines are empirically based. A series of two-dimensional numerical direct shear tests are performed to investigate this scaling effect. By analyzing the bulk friction, particle translation and rotation, percentage of sliding, average volume (area) and shear strain and the evolution of the shear band, we find that the traditional guidelines for direct shear tests are questionable. Scaling dependency of bulk friction on the property of granular materials is clearly present. Our current analysis points out that the scaling effects can vary significantly depending on the particle properties other than their sizes. Of all the parameters we observed, particle rotation appears to have a decisive correlation with the bulk friction. Formation of a shear band is universal. As the shearing progresses, particle rotation begins to concentrate near the shear plane. By defining the width of a shear band as the standard deviation of the distribution of translational gradient or the standard deviation of the distribution of particle rotation, quantitative evolutions of shear band are presented. Both measures of the shear band width dropped rapidly during pre-failure stage. After peak stress both measures begin to approach steady state as the bulk friction stabilizes to the residual stage. These observations suggest that structure formation inside the shear band controls the scaling effect.

关键词：直接剪切试验测试土力学土工试验

Validation of MODIS ocean-colour products in the coastal waters of the Yellow Sea and East China Sea

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Acta Oceanologica Sinica 2020年第1期39卷 91-101页

作者： Lingling Jiang Xiangyu Guo Lin Wang Shubha Sathyendranath hayley Evers-King Yanlong Chen Bingnan Li College of Environmental Science and Engineering Dalian Maritime UniversityDalian 116026China Ministry of Ecology Environment National Marine Environmental Monitoring CenterDalian 116023China Plymouth Marine Laboratory(PML) PlymouthDevonPL13DHUK

An extensive study collected in situ data along the Yellow Sea(YS) and East China Sea(ECS) to assess the radiometric properties and the concentration of the water constituents derived from Moderate Resolution Imaging Spectroradiometer(MODIS). Thirteen high quality match-ups were obtained for evaluating the MODIS estimates of Rrs(λ), chlorophyll a(Chl a) and concentrations of suspended particulate sediment matter(SPM). For MODIS Rrs(λ), the mean absolute percentage difference(APD) was in the range of 20%–36%, and the highest uncertainty appeared at 412 nm, whereas the band ratio of Rrs(λ) at 488 nm compared with that at 547 nm was highly consistent, with an APD of 7%. A combination of near-infrared bands and shortwave infrared wavelengths atmosphere correction algorithm(NIR-SWIR algorithm) was applied to the MODIS data, and the estimation accuracy of Rrs were improved at most of the visible spectral bands except 645 nm, 667 nm and 678 nm. Two ocean-colour empirical algorithms for Chl a estimation were applied to the processed data, the results indicated that the accuracy of the derived Chl a values was obviously improved, the four-band algorithms outperformed the other algorithm for measured and simulated datasets, and the minimum APD was 35%. The SPM was also quantified. Two regional and two coastal SPM algorithms were modified according to the in situ data. By comparison, the modified Tassan model had a higher accuracy for the application along the YS and ECS with an APD of 21%. However, given the limited match-up dataset and the potential influence of the aerosol properties on atmosphere correction, further research is required to develop additional algorithms especially for the low Chl a coastal water.

关键词： MODIS turbid waters chlorophyll a SPM retrieval algorithms Yellow and East China Sea

A comparison of handheld and standard ultrasound in Swiss medical students

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World Journal of Emergency Medicine 2022年第2期13卷 85-90页

作者： Mark Slader hayley Young Margot Barker Kylie Prentice Katherine Bogaard Charlene Yuan Soheil Saadat Shadi Lahham School of Medicine University of CaliforniaIrvine 92617USA Department of Emergency Medicine University of CaliforniaIrvine 92868USA

BACKGROUND:The use of ultrasound(US)within healthcare has inspired the development of new US *** have been few studies comparing the use of handheld US to standard US for medical *** research aims to determine whether a handheld US device can provide a comparable primary learning experience to that of a standard US ***:Over two days of instruction,participants were taught and evaluated on core US *** standard group received instruction on standard US machines,while the handheld group received instruction on handheld US *** completed a qualitative survey regarding their *** hundred and four images were obtained and graded by two emergency medicine ***:A total of 119 Swiss medical students were enrolled in our *** was no statistically significant difference in the US assessment measurements,except for faster endpoint septal separation(EPSS)vascular setup time in the handheld group(P=0.001).There was no statistically significant difference in participants’perceived difficulty of US learning(P=0.198),comfort level(P=0.188),or self-estimated capability to perform US in the future(P=0.442).There was no statistically significant difference in the percentage of correctly obtained images(P=0.211)or images that were clinically useful(P=0.256).The median quality score of images obtained by the standard group was eight compared to seven in handheld group(P<0.01).CONCLUSION:Our data suggest a handheld US machine can perform as well as a standard US machine as an educational tool despite sacrifices in image quality.

关键词： Handheld ultrasound Ultrasound education Switzerland Medical education