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Now showing items 17 - 32 of 446

  • Effects of Bearing Preload, Oil Volume, and Operating Temperature on Axle Power Losses

    Xu, Hai   Singh, Avinash   Kahraman, Ahmet   Hurley, Joshua   Shon, Sam  

    In order to boost the fuel economy of their vehicles, automotive Original Equipment Manufacturers (OEMs) and suppliers have been investigating a range of options from alternate vehicle propulsion systems down to optimized component level technologies. The hypoid gear set in a rear axle is one of the least efficient drive train components, and as such, provides unique opportunities for improvements. It has therefore attracted significant attention from researchers to reduce the power losses. Both loaded and unloaded power losses have been studied before and found to vary significantly with load and speed conditions. This paper will focus on the effects of the axle pinion bearing preload, axle gear oil levels, and operating temperatures on axle power losses during the fuel economy driving cycles where both axle load and speed vary significantly. In this paper, power loss measurements from experiments conducted on an automotive rear drive axle on a dedicated dynamometer will be presented. Tests were conducted under a range of speed and load conditions that were developed from Environmental Protection Agency (EPA) fuel economy driving cycles. Both urban and highway cycles were included in the tests. Separate tests were conducted for unloaded spin losses and loaded power losses. The tests were conducted at a few different controlled levels of gear oil operating temperatures, gear oil volumes, and pinion bearing preloads, and their influence on power losses was quantified. The measured power losses at a matrix of load and speed conditions provide a series of power loss maps as a function of gear oil operating temperature, oil volume, and bearing preload. Using these power loss maps, the overall axle efficiency or power loss during any driving cycle can be quantified by integrating the instantaneous power losses as the axle goes through the driving cycles. Similar maps can be created for other influences and the proposed procedure can be utilized to quantify their influences on a given driving cycle. Results from this study indicate that with the combination of appropriate preloads, gear oil volume, and temperature control, axle efficiency can potentially be improved by roughly 3% in the tested axle. [DOI:10.1115/1.4006325]
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    Seismic data acquired by independent simultaneous sweeping (ISS ) techniques are processed is to attenuate random uncompressed cross-talk signals and improve the resolution of the pre-stack migrated time image. A frequency- varying mean filter is applied on cross- spread offset-azimuth gathers of the data. The frequency-space domain filter may vary its window size according to the characteristics of the cross-talk.
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  • Late Holocene Indian summer monsoon variations recorded at Lake Erhai, Southwestern China

    Xu, Hai   Zhou, Xinying   Lan, Jianghu   Liu, Bin   Sheng, Enguo   Yu, Keke   Cheng, Peng   Wu, Feng   Hong, Bin   Yeager, Kevin M.   Xu, Sheng  

    In this study we report changes in Indian summer monsoon (ISM) intensity during the past 3500 yr inferred from proxy indices at Lake Erhai, southwestern China. Both the pollen concentrations and other proxy indices, including sediment grain size, total organic carbon contents (TOC), and elemental contents (e.g., Fe, Al), clearly indicate a long term decreasing trend in ISM intensity over the late Holocene. During the period from approximately AD 750 to AD 1200, pollen concentrations of conifer and broadleaf trees, and herbs reached the lowest levels over the past 3500 yr; while the pollen percentages of both herbs and broadleaf trees increased, suggesting a significant medieval drought. The grain size, TOC, and elemental contents also support an arid climate during the medieval period. The Little Ice Age (LIA) at Lake Erhai was characterized as cold and wet. The medieval and LIA climatic patterns at Lake Erhai were similar to those over most of the ISM areas, but anti-phase with those over East Asian summer monsoon (EASM) areas. We suspect that sea surface temperature variations in the Indo-Pacific oceans and the related land-sea thermal contrasts may be responsible for such hydroclimatic differences between EASM and ISM areas. (C) 2014 University of Washington. Published by Elsevier Inc. All rights reserved.
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  • The effect of antibody surface packing density on its antigen binding capacity

    Xu, Hai   Williams, David   Lu, Jian  

    Following our recent study of the binding of antigen hCG (human chorionic gonadotropin) onto a mouse monoclonal antibody anti-beta-hCG immobilized onto the support surface, we report a more recent study of the site-specific recognition of another surface immobilized mouse monoclonal antibody anti-alpha-hCG by hCG. The two antibodies have similar structures and molecular weights but different site-specific recognition from hCG. They both are used in the fabrication of fertility test immunoassays. Previous study by neutron reflection has indicated the "flat-on" orientation of anti-beta-hCG with its Fc and two Fabs lying flat on the support surface. The aim of this work is to determine if there is any measurable difference in hCG binding between the two antibodies that could be attributed to the steric hindrance associated with specific binding sites. The adsorption and hCG binding for anti-alpha-hCG were made under the surface and in solutions as for anti-beta-hCG so that the outcome could be directly compared. The results show that the two antibodies are bound by hCG in an almost identical fashion, suggesting that apart from the site-specific recognition there is no measurable difference in the steric hindrance between the alpha and beta sites.
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  • An ESIPT-based fluorescent probe for the detection of phosgene in the solution and gas phases

    Wu, Cuiyan   Xu, Hai   Li, Yaqian   Xie, Ruihua   Li, Peijuan   Pang, Xiao   Zhou, Zile   Gu, Biao   Li, Haitao   Zhang, Youyu  

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  • Differential transformation efficiency of Japonicarice varieties developed in northern China

    Li, Dan   Xu, Hai   Sun, Xiaoxue   Cui, Zhibo   Zhang, Yuan   Bai, Yuguan   Wang, Xiaoxue   Chen, Wenfu  

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  • Deuterated Ethanol as a Probe for Measuring Equilibrium Isotope Effects for Hydroxyl Exchange

    Xu, Hai   Zhao, Siqi   Xiong, Xiang   Yao, Jiayao   Cross, R. James   Saunders, Martin  

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    Acquisition of data by managing crosstalk interference with sector designs and unique sweeps is conducted and the resultant data are processed in 3D common receiver domain to attenuate crosstalk noise while preserving the signals for high source and receiver density acquisition designs. High-amplitude spectral amplitudes are attenuated and inter-ensemble statics or structural time delays are applied to achieve optimum filter performance. If the spectral amplitudes have been attenuated to a level consistent with non-simultaneous acquisition, conventional surface consistent processing can be performed to correct for statics and amplitude variations. A 3-point filter in different frequency bands may then be applied to remove any remaining residual crosstalk noise.
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    The present invention relates to the fields of organic synthesis and pharmaceutical chemistry, and specifically relates to a β-elemene 14-position derivative (I) or (II), wherein R1 and R2 are defined in the description. Also disclosed in the present invention are a method for preparing said β-elemene 14-position derivatives and the anti-atherosclerotic application of same.
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    The present invention relates to the fields of organic synthesis and pharmaceutical chemistry, and specifically relates to a β-elemene 13-position derivative (I) or (II), wherein R1 and R2 are defined in the description. Also disclosed in the present invention are a method for preparing said β-elemene 13-position derivatives and the anti-atherosclerotic application of same.
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  • Solar activity and the westerlies dominate decadal hydroclimatic changes over arid Central Asia

    Yan, Dongna   Xu, Hai   Lan, Jianghu   Zhou, Kangen   Ye, Yuanda   Zhang, Jixiao   An, Zhisheng   Yeager, Kevin M.  

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  • Domino Aryne Annulation via Nucleophilic-Ene Process

    Xu, Hai   He, Jia   Shi, Jiarong   Tan, Liang   Qiu, Dachuan   Luo, Xiaohua   Li, Yang  

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  • Growth response ofMicrocystisspp. to iron enrichment in different regions of Lake Taihu, China

    Xu, Hai   Zhu, Guangwei   Qin, Boqiang   Paerl, Hans W.  

    Iron (Fe) is an essential micronutrient for algal growth and can be a potential limiting nutrient in aquatic system, especially regions that exhibits nitrogen (N) limitation. Using short-term nutrient addition bioassays, we evaluated the potential role that iron might play in modifying the response of Microcystis spp. to the anthropogenic phosphorus (P) and N enrichment in hypereutrophic Lake Taihu, the third largest freshwater lake in China. Three nutrient enrichment experiments involving additions of N (as NO3-) and P (as PO43-) with and without Fe were conducted during 2009-2010 in Meiliang Bay, a region characterized by summer cyanobacterial (Microcystis spp.) blooms, and East Taihu, a region largely free of cyanobacterial blooms and dominated by macrophytes. In Meiliang Bay, Fe addition alone did not significantly increase Microcystis spp. biomass. However, Fe addition occasionally increased the stimulatory effect of N and P additions on Microcystis spp., indicating that Fe was not a primary limiting nutrient for Microcystis spp. growth. Occasionally Fe was co-limiting with N and P in this region. In East Taihu, the addition of Fe alone significantly stimulated Microcystis spp. growth, while addition of N and/or P had no effects on growth, indicating that Fe was a primary limiting nutrient in East Taihu. The combined addition of Fe and N resulted in a growth response similar to Fe alone, while combined addition of Fe and P yielded greater biomass increases than the addition of Fe alone. This indicated that in East Taihu, N was not limiting and Fe and P supplies facilitated Microcystis spp. growth. These results reflect differential availabilities and limitations of N, P, and Fe in distinct regions of Taihu. The potential role of Fe in eutrophication dynamics of large, regionally complex lakes like Taihu requires further attention.
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  • Decadal/multi-decadal temperature discrepancies along the eastern margin of the Tibetan Plateau

    Xu, Hai   Sheng, Enguo   Lan, Jianghu   Liu, Bin   Yu, Keke   Che, Shuai  

    Knowledge of the synchronicity and discrepancy of temperature variations along the Eastern margin of the Tibetan Plateau (ETP) is critical in understanding the driving forcing of regional temperature variations. In this study, we established delta 15N timeseries in organic matter and delta 13C timeseries in ostracod shells from sediments of Lake Lugu and attributed their variations to decadal/multi-decadal temperature variations. We compared temperature variations along the ETP transect during the past four centuries based on our presently developed and previously developed temperature proxy indices, as well as temperature variations reconstructed by other researchers. We found that: (1) Over the north ETP area (N-ETP), the decadal/multi-decadal variations in temperature correlate well with each other. (2) Over the south ETP area (S-ETP), temperature variations correlate not so well with each other; while those at south to west portion of the Tibetan Plateau are rather local. (3) The decadal variations in temperature are generally synchronous with those in precipitation over the N-ETP area, and they are broadly anti-phase/out-of-phase with the corresponding ones over the S-ETP area. (4) The long term temperature and precipitation trends are coupling over the N-ETP but decoupling over the S-ETP. We speculate that because the N-ETP is located at the frontier of the Asian summer monsoon (ASM) region, temperature variations there are not as strongly influenced by the ASM; they are most likely dominated by changes in solar activities, and show general similarity to the average of the Northern Hemisphere. Over the S-ETP area, decadal temperature variations are obviously influenced by precipitation. Because the decadal/multi-decadal precipitation variations are anti-phase and/or out-of-phase between the N-ETP and S-ETP, the decadal/multi-decadal temperature variations between these two regions are also anti-phase and/or out-of-phase. [All rights reserved Elsevier].
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  • Inhibition of mitochondrial respiration overcomes hepatocellular carcinoma chemoresistance

    Sun, Yuan   Xu, Hai   Chen, Xinju   Li, Xiaodong   Luo, Baoping  

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  • Modern carbon burial in Lake Qinghai, China

    Xu, Hai   Lan, Jianghu   Liu, Bin   Sheng, Enguo   Yeager, Kevin M.  

    The quantification of carbon burial in lake sediments, and carbon fluxes derived from different origins are crucial to understand modern lacustrine carbon budgets, and to assess the role of lakes in the global carbon cycle. In this study, we estimated carbon burial in the sediment of Lake Qinghai, the largest inland lake in China, and the carbon fluxes derived from different origins. We find that: (1) The organic carbon burial rate in lake sediment is approximately 7.23 g m (2) a (1), which is comparable to rates documented in many large lakes worldwide. We determined that the flux of riverine particulate organic carbon (POC) is approximately 10 times higher than that of dissolved organic carbon (DOC). Organic matter in lake sediments is primarily derived from POC in lake water, of which approximately 80% is of terrestrial origin. (2) The inorganic carbon burial rate in lake sediment is slightly higher than that of organic carbon. The flux of riverine dissolved inorganic carbon (DIC) is approximately 20 times that of DOC, and more than 70% of the riverine DIC is drawn directly and/or indirectly from atmospheric CO2. (3) Both DIC and DOC are concentrated in lake water, suggesting that the lake serves as a sink for both organic and inorganic carbon over long term timescales. (4) Our analysis suggests that the carbon burial rates in Lake Qinghai would be much higher in warmer climatic periods than in cold ones, implying a growing role in the global carbon cycle under a continued global warming scenario. (C) 2013 Elsevier Ltd. All rights reserved.
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