26 research outputs found

    Parched elastohydrodynamic lubrication: Instrumentation and procedure

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    A counter rotating bearing rig was designed and constructed to study transient elastohydrodynamic lubrication phenomena. New instrumentation is described and test procedures are documented. Ball and race speed measurement systems and the capacitance (film thickness) measurement system were upgraded. Methods for measuring bearing torque and race temperatures were implemented

    Comparison of Mg/Ca- and alkenone-based sea surface temperature estimates in the fresh water-influenced Gulf of Guinea, eastern equatorial Atlantic

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    This study presents a comparison of sea surface temperature (SST) estimates based on Mg/Ca ratios of Globigerinoides ruber and alkenone unsaturation index (U37 K′) in core sediment recovered from the Gulf of Guinea, eastern equatorial Atlantic. Mg/Ca- and U37 K′-based SST estimates yield fairly comparable results for the time interval 21,000–14,500 years and for the late Holocene. The early and middle Holocene, however, are largely characterized by a discrepant trend, with warm Mg/Ca and cold U37 K′ based SST estimates. This discrepant SST trend is accompanied by low sea surface salinity estimates (high riverine runoff) and biogenic sediment, which is characterized by high biogenic opal content, low carbonate content, and relatively low alkenone concentration. We hypothesize that the discrepancy in the reconstructed SSTs during the middle and early Holocene presumably suggests a period of elevated riverine input of dissolved silica and dominantly siliceous phytoplankton bloom in a low saline and warm surface water, while alkenone producers were likely prevalent in a season of cold SST and low riverine silica input. This study suggests that changes in the local hydrography and nutrient input have strong influence on the U37 K′-based SST estimate that may be unraveled by combining different SST proxies

    Sea surface and subsurface circulation dynamics off equatorial Peru during the last ~17 kyr

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    The complex deglacial to Holocene oceanographic development in the Gulf of Guayaquil (Eastern Equatorial Pacific) is reconstructed for sea surface and subsurface ocean levels from (isotope) geochemical proxies based on marine sediment cores. At sea surface, southern sourced Cold Coastal Water and tropical Equatorial Surface Water/Tropical Surface Water are intimately related. In particular since ~10 ka, independent sea surface temperature proxies capturing different seasons emphasize the growing seasonal contrast in the Gulf of Guayaquil, which is in contrast to ocean areas further offshore. Cold Coastal Water became rapidly present in the Gulf of Guayaquil during the austral winter season in line with the strengthening of the Southeast Trades, while coastal upwelling off Peru gradually intensified and expanded northward in response to a seasonally changing atmospheric circulation pattern affecting the core locations intensively since 4 ka BP. Equatorial Surface Water, instead, was displaced and Tropical Surface Water moved northward together with the Equatorial Front. At subsurface, the presence of Equatorial Under Current-sourced Equatorial Subsurface Water was continuously growing, prominently since ~10–8 ka B.P. During Heinrich Stadial 1 and large parts of the Bølling/Allerød, and similarly during short Holocene time intervals at ~5.1–4 ka B.P. and ~1.5–0.5 ka B.P., the admixture of Equatorial Subsurface Water was reduced in response to both short-term weakening of Equatorial Under Current strength from the northwest and emplacement by tropical Equatorial Surface Water, considerably warming the uppermost ocean layers

    An approach for evaluating the market effects of energy efficiency programs

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    This paper presents work currently being carried out in California on evaluating market effects. We first outline an approach for conducting market effect studies that includes the six key steps that were developed in study plans: (1) a scoping study that characterizes a particular market, reviews relevant market effects studies, develops integrated market and program theories, and identifies market indicators; (2) analysis of market evolution, using existing data sources; (3) analysis of market effects, based on sales data and interviews with key market actors; (4) analysis of attribution; (5) estimation of energy savings; and (6) assessment of sustainability (i.e., the extent to which any observed market effects are likely to persist in the absence or reduction of public intervention, and thus has helped to transform the market).We describe the challenges in conducting this type of analysis (1) selecting a comparison state(s) to California for a baseline, (2) availability and quality of data (limiting analyses), (3) inconsistent patterns of results, and (4) conducting market effects evaluations at one point in time, without the benefit of years of accumulated research findings, and then provide some suggestions for future research on the evaluation of market effects. With the promulgation of market transformation programs, the evaluation of market effects will be critical. We envision that these market effects studies will help lay the foundation for the refinement of techniques for measuring the impacts of programs that seek to transform markets for energy efficiency products and practices
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