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151.
152.
Brack V 《Environmental management》2007,40(5):739-746
Understanding temperatures used by hibernating bats will aid conservation and management efforts for many species. A limestone
mine with 71 km of passages, used as a hibernaculum by approximately 30,000 bats, was visited four times during a 6-year period.
The mine had been surveyed and mapped; therefore, bats could be precisely located and temperatures (T
s) of the entire hibernaculum ceiling accurately mapped. It was predicted that bats should hibernate between 5 and 10°C to
(1) use temperatures that allow a near minimal metabolic rate, (2) maximize the duration of hibernation bouts, (3) avoid more
frequent and prolonged arousal at higher temperatures, (4) avoid cold and freezing temperatures that require an increase in
metabolism and a decrease in duration of hibernation bouts or that could cause death, and (5) balance benefits of a reduced
metabolic rate and costs of metabolic depression. The distribution of each species was not random for location (P < 0.000) or T
s (P < 0.000). Myotis sodalis (Indiana bat) was most restricted in areas occupied, hibernating in thermally stable yet cold areas (
= 8.4 ± 1.7°C); 99% associated with cement block walls and sheltered alcoves, which perhaps dampened air movement and temperature
fluctuations. Myotis lucifugus (little brown myotis) hibernated in colder, more variable areas (
= 7.2 ± 2.6°C). Myotis septentrionalis (northern myotis), Pipistrellus subflavus (eastern pipistrelle), and Eptesicus fuscus (big brown bat) typically hibernated in warm, thermally stable areas (
= 9.1 ± 0.2°C,
= 9.6 ± 1.9°C, and
= 9.5 ± 1.5°C, respectively). These data do not indicate that hibernacula for M. sodalis, an endangered species, should be manipulated to cool below 5°C. 相似文献
153.
154.
The aggregation and deposition of carbon nanotubes(CNTs) determines their transport and fate in natural waters.Therefore,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes(HA-MWCNTs) was investigated by time-resolved dynamic light scattering in NaCl and CaCl_2 electrolyte solutions.Increased ionic strength induced HA-MWCNT aggregation due to the less negative zeta potential and the reduced electrostatic repulsion.The critical coagulation concentration(CCC) values of HA-MWCNTs were 80 mmol/L in NaCl and 1.3 mmol/L in CaCl_2 electrolyte,showing that Ca~(2+) causes more serious aggregation than Na~+.The aggregation behavior of HA-MWCNTs was consistent with Derjaguin-Landau-Verwey-Overbeek theory.The deposition kinetics of HA-MWCNTs was measured by the optical absorbance at 800 ran.The critical deposition concentrations for HA-MWCNT in NaCl and CaCl_2 solutions were close to the CCC values,therefore the rate of deposition cannot be increased by changing the ionic strength in the diffusion-limited aggregation regime.The deposition process was correlated to the aggregation since larger aggregates increased gravitational deposition and decreased random Brownian diffusion.HA-MWCNTs hydrodynamic diameters were evaluated at 5,15 and 25℃.Higher temperature caused faster aggregation due to the reduced electrostatic repulsion and increased random Brownian motion and collision frequency.HA-MWCNTs aggregate faster at higher temperature in either NaCl or CaCl_2electrolyte due to the decreased electrostatic repulsion and increased random Brownian motion.Our results suggest that CNT aggregation and deposition are two correlated processes governed by the electrolyte,and CNT transport is favored at low ionic strength and low temperature. 相似文献
155.
《Journal of Manufacturing Processes》2014,16(2):248-256
Magnetic abrasive finishing (MAF) is a process in which the work surface is finished by removing the material in the form of micro chips by magnetic abrasive particles (MAPs) in the presence of magnetic field in the finishing zone. During the MAF process, the frictional heat is generated at the workpiece surface due to the rubbing action of magnetic abrasive particles with the work surface. The order of temperature rise is important to study, as finishing mechanism and surface integrity of work materials depend upon it. The measurement of temperature distribution during MAF operation at the interface of work piece and flexible magnetic abrasive brush (FMAB) interface is difficult. In the present analysis, finite element based ANSYS software has been used to model and simulate magnetic field distribution, magnetic pressure and temperature distribution at work-brush interface during the process. In this work the maximum magnetic flux density has been simulated of the order of 0.223 T at 0.91 A of current in electromagnet coil. Magnetic pressure on MAPs due to magnetic field of electromagnetic coil has been calculated to evaluate the frictional heat flux generated at the work-brush interface. Transient thermal analysis of workpiece domain has been performed to predict the temperature rise due to frictional heat flux. The predicted temperature on work-brush interface was found in the range of 34–51 °C. The developed simulation results based on FEA have been validated with experimental findings. 相似文献
156.
Yajun Wang Xiaoming Zhang Qi Feng Jiexin Zou Chang Zhou Lin Zeng 《International Journal of Green Energy》2020,17(2):157-170
ABSTRACTCarbon corrosion caused by H2/O2 interface during the shut-down process is one of the factors that exacerbate the overall degradation of proton exchange membrane fuel cells (PEMFC) in automotive applications. Numerous studies have shown that system strategies are beneficial for reducing the duration of H2/O2 interface and alleviating performance degradation. In this paper, three different shut-down strategies are investigated and compared based on the internal behaviors acquired by in-situ measurements. For the three shut-down strategies, reverse current and high potential are mainly observed in a lower constant current and constant power strategy. Comparatively speaking, the internal uniformity of the cell under constant current and power load is better than that with constant voltage strategy when the shut-down time is about the same. The results suggest that adopting a higher constant power load followed by a larger voltage load during the shut-down process can effectively shorten the shut-down time and relieve carbon corrosion. These results add significant new insights into the shut-down process and will be of practical importance in directing design of combined shut-down strategy that can withstand carbon corrosion. 相似文献
157.
SBR法处理高浓度有机废水试验研究 总被引:2,自引:0,他引:2
采用序批式活性污泥法(SBR),对处理高浓度化工废水进行了实验研究,结果表明,温度是影响SBR法处理效果的一处重要因素,其次是pH值、曝气量和周期,并在一定条件下,可得到75%的CODcr去除率。 相似文献
158.
159.
膜—生物反应器特性影响因素研究 总被引:8,自引:0,他引:8
通过对外压管式膜组件与曝气池构成的好氧膜生物反应器的研究,分别考究膜组件的操作压力,膜面流速以及活性污泥混合液的污泥浓度,溶解性有机特的含量和温度等对膜通量的影响。 相似文献
160.
逆温对吴淞工业区大气质量影响个例分析 总被引:1,自引:0,他引:1
以吴淞工业区冬夏二次大气质量监测数据和同时期龙华观象台的探空资料为依据,详细地描述了逆温对大气污染物(SO_2和NO_x)时空变化的影响,并阐述了形成这样的空间分布的污染源排放特点和主要贡献源。为环境管理和规划的实施,提供了科学依据。 相似文献