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Population persistence of the perennial kelp Eisenia arborea varies across local spatial scales
Daniel J. Gossard,Diana L. Steller 한국조류학회I 2022 ALGAE Vol.37 No.1
Perennial stipitate kelps are globally distributed and individual species can inhabit broad latitudinal ranges, expressing notably longevous persistence. Despite the foundational role kelps provide to their communities, little is known about the variability in persistence of the stipitate kelps at local spatial scales. We studied the population persistence of Eisenia arborea, a heat- and wave force-tolerant perennial stipitate kelp with a distributional range extending from British Columbia to south of the range limit of all other northeast Pacific kelps, in Baja California Sur, Mexico. Persistence characteristics for E. arborea among sites were compared and used to test the hypothesis that stand persistence varied at local spatial scales around Isla Natividad, a Pacific island off the Baja California peninsula with documented spatiotemporal environmental heterogeneity. Collected individuals around the island were “aged” using the previously validated age estimation technique of counting annual cortical dark rings. After detecting no significant differences among sites in the covariation between estimated ages for collected individuals and stipe length, we utilized in-situ population-level stipe length measurements to more rapidly predict age structures within six stands around the island. Predicted age structures, and associated stand densities, revealed persistence characteristics and density varied at local scales and a strong positive relationship existed between stand density and stand mean and maximum ages. We speculate that stands responded differently to deterministic influences (e.g., the 2014–2016 marine heatwave and / or competition with Macrocystis) resulting in heterogenous local persistence of this foundation species.
Computational Method for Identifying Critical Dimensions in the Automobile Body Assembly
Chang, Min Ho,Kim, J. H.,Gossard, David C. 대한기계학회 1996 International Sessions in Celebration of the 50th Vol.1 No.1
This paper proposes a method for identifying critical dimensions in large sheet metal structures such as automobile bodies. The proposed method simulates the propagation. of variations during the assembly process to identify the dimensions in individual parts and assembly tooling that most affect the quality of the final product. The identified critical dimensions can be used to select measuring points, to allocate tolerances, and to evaluate the design. An example of an automobile front-end assembly its used through the paper to illustrate the method.
나노구조물 첨가를 이용한 고온에서의 고체 열전도도 감소
김우철(Woochul Kim),김강민(Kangmin Kim),박준영(Junyoung Park),Suzanne L. Singer,Arun Majumdar,Dmitri Klenov,Arthur C. Gossard,Susanne Stemmer,Joshua M. O. Zide 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Thermal conductivity of a crystalline solid at high temperature is dominated by the Umklapp process because the number of high frequency phonons increases as with temperature. It is challenging to reduce the thermal conductivity of crystalline solids at high temperature although it is widely known that by increasing the atomic defect concentration, thermal conductivity of crystalline solids can be reduced at low temperature. By increasing the concentration of ErAs nanoparticles in In0.53Ga0.47 As up to 6 atomic percent, we demonstrate a thermal conductivity reduction by almost a factor of three below that of In0.53Ga0.47 As at high temperature. A theoretical model suggests that the mean free path of the low frequency phonons is suppressed by increasing the ErAs nanoparticle concentration.