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This research attempts to observe indirectly the variation of internal bond characteristics for wood composite materials during accelerated aging test treatment using ultrasonic pulse-transmission techniques. Particleboard (PB) and oriented strandboard (OSB) were the representative specimens. The transit time of the ultrasonic wave propagating through the samples along the nominal length and thickness directions was recorded using an apparatus called PUNDIT (C.N.S. Electronic, London). The transit times were measured in the samples under an oven-dried condition after treating them with boiling water at different treating time stages, and the velocity was then calculated based on the transit time. Examination of the internal bond strength conducted on the same samples was done according to JIS A 5908. A study of the relations among springback, internal bond strength, and velocity indicated that a high correlation existed between ultrasonic velocity measured in the length or thickness direction and the internal bond strength for the PB specimen, but no significant correlation was observed between the velocity measured in the length direction and the internal bond strength for the OSB specimen. The results of this research suggested that ultrasound techniques can be applied to predict or evaluate the internal bond state of some wood-composite materials made of relatively small particles, such as PB especially, during accelerated aging test treatment processes.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997 相似文献
44.
李云阳 《拖拉机与农用运输车》2010,37(5)
介绍一种基于单片机的脉冲反射式超声测距系统,提出了系统的总体构成,针对测距系统发射、接收、检测、显示部分的总体设计方案进行了论证,分析了系统各部分的硬件及软件实现。最后文中分析了误差产生的原因,并对系统完善提出了一些建议。 相似文献
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用脂肪酶对罗非鱼鱼皮进行酶法脱脂工艺研究。通过单因素与正交试验确定最适的酶法脱脂工艺为:pH值9,脱脂时间3h,酶添加量2%,料液比1:4,温度40℃,该工艺的脱脂率可达67.5%。通过超声波辅助脱脂研究表明其脱脂率并无明显的提高。 相似文献
47.
The swimming depths of 12 individual Nemopilema nomurai with bell diameters of 0.8–1.6 m were investigated using pop-up archival transmitting tags and ultrasonic pingers, and the
validity of the research method was evaluated. The N. nomurai studied frequently showed vertical movement, with the swimming depth ranging from 0 to 176 m, The mean swimming depths of
most individuals were less than 40 m. The swimming depths of N. nomurai in the northern Japan Sea in the winter were mostly deeper than those of this species in the southern Japan Sea in the autumn.
This result suggests that the range of the depths almost depends on the vertical structure of the ocean. Swimming depths during
the nighttime were significantly deeper than those during the daytime. More specifically, during the daytime, the swimming
depths in the afternoon tended to be shallower than those in the morning, while during the nighttime, the swimming depths
after midnight were deeper than those before midnight. 相似文献
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研究紫花苜蓿(Medicago sativa L.)叶总黄酮的最优提取工艺及体外抗氧化能力。在单因素试验的基础上设计正交试验,通过方差分析和多重比较确定最优提取工艺。以1,1-二苯基-2-三硝基苯肼(2,2-diphenyl-1-picrylhydrazyl,DPPH)清除率测定法及还原力测定法评价苜蓿黄酮类化合物体外抗氧化活性。最佳提取工艺条件是:乙醇体积分数70%、提取温度60℃、提取时间30 min、超声功率180 w,总黄酮得率为6.43 mg·g-1。苜蓿叶总黄酮在一定的质量浓度范围具有较明显的抗氧化活性,并随着质量浓度的增加活性增强。苜蓿叶总黄酮具有较强的还原力,清除DPPH自由基的半数抑制质量浓度(IC50值)为0.608 mg·mL-1。超声提取是一种高效的提取紫花苜蓿叶总黄酮方法。超声优化的苜蓿叶总黄酮提取工艺经济、稳定、合理可行。 相似文献
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[目的]利用响应面法优化超声提取甘草浸膏中甘草酸的工艺条件。[方法]在乙醇浓度、超声波时间及料液比等单因素试验的基础上,根据Box-Behnken的中心组合设计原理采用3因素3水平的响应面分析法优化超声波提取甘草酸的工艺条件。[结果]超声提取甘草酸的最佳工艺条件为乙醇浓度70%、超声波时间30 min、料液比2.8 g/L,在此条件下甘草酸含量为8.34%。[结论]建立了甘草浸膏中甘草酸超声提取最佳工艺条件,为甘草浸膏的精深加工及进一步研究甘草酸在食品和医药领域产业化应用提供理论依据。 相似文献
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