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91.
This article presents the experimental results of an evaluation of the influence of internal flow patterns on the heat transfer performance of a closed-loop oscillating heat pipe with check valves. It was found that the internal flow patterns could be classified according to four flow patterns: dispersed bubble flow, bubble flow, slug flow, and annular flow, respectively. The main regime of each flow pattern can be determined from a flow pattern map. The map can be used to predict the trend of the heat transfer rate in the closed-loop oscillating heat pipe with check valves. 相似文献
92.
A study of wave propagation in buried pipe conveying fluid is presented in the paper. The Flüggle shell model is adopted for pipe and surrounding solid is modeled as elastic matrix by using Winkle model. Wave dispersion curves of a buried vacant pipe and a pipe conveying fluid are obtained numerically by considering coupling conditions. Results show that wave velocity exhibits sharp drop points in dispersion curves, and remains to an identical values before and after the points for both of vacant pipe and pipe conveying fluid. Effects of wall thickness, elastic matrix properties and fluid velocity are also discussed. 相似文献
93.
声波在气体中传播时,气体的热粘性效应会使声波产生一定程度的衰减,且气体的声吸收系数随温度的升高而增大。由于发动机的排气温度较高,热粘性效应引起的排气管道中的噪声衰减应加以考虑。基于准平面波理论,首次计算了考虑热粘性效应时不同温度、流速和管道尺寸下排气管道中的传递损失,分析了各参数对管道中噪声衰减的影响。结果表明,随着温度和频率的升高热粘性声衰减增强,而气流流速和管道直径的增加会降低直管中的热粘性声衰减。对于简单膨胀腔,传递损失的预测结果表明,热粘性效应使通过频率处的声衰减有所改善。 相似文献
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96.
Khay S Abd El-Aty AM Cho SK Choi JH Mamun MI Goudah A Shin HC Shim JH 《Biomedical chromatography : BMC》2008,22(6):581-589
This study was undertaken to investigate whether an additional column clean-up procedure can affect the accuracy of an analytical method developed for the determination of imidacloprid residues in Chinese cabbage. Thereafter, the residue levels and the degradation rates of imidacloprid were investigated in experimental Chinese cabbage plots after treatment with two different commercial formulations: emulsifiable concentrate (EC) and wettable powder (WP). The analyte was determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) and confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) in the select ion-monitoring mode. The mean recoveries ranged from 75.34 to 98.00% and 96.95 to 100.97%, with relative standard deviations of 0.86-4.14 and 1.22-3.52%, in samples treated with and without additional column clean-up procedures, respectively. The minimum detectable amount of imidacloprid was 4 ng, while the limits of detection and quantitation were 0.2 and 0.5 ppm, respectively. The degradation of pesticide was monitored throughout a period of 13 days under greenhouse conditions. Although the behaviors of the EC and WP formulations appear to be similar, the absolute residue levels obtained with EC and WP treatments differed slightly. When imidacloprid formulations were applied (as foliar treatments) according to the recommended rate, the final residues (13 days post-treatment) in Chinese cabbage were much lower than the maximum residue limit (MRL = 3.5 ppm) established by the Korean Food and Drug Administration. Taken together, our study suggests that the analysis of imidacloprid can be performed without an additional column clean-up procedure, and the decline curve and the residue levels in Chinese cabbage could change if the same active ingredient is used in different formulations. 相似文献
97.
In bottom-viewed inductively coupled plasma-atomic emission spectrometry (BV-ICP-AES), emission from the central channel of the plasma is measured axially from the bottom of the plasma. A straight quartz tube was used as a hollow light pipe (HLP) to collect plasma emission in this study. The HLP also serves as an injector for aerosols transport and injection into the ICP. The optical characteristics of HLPs with the original reflective surface and roughened outer surface are reported. The roughened HLP is effective in rejecting light beams that are not in line with the HLP. The transmission efficiency of the HLP, however, is high (> 70%) for light beams from a source that has the same dimension as the entrance of the HLP and is flush with the HLP. The HLP is effective in rejecting background emission from the core of the plasma that encircles the plasma central channel and yet efficient in light collection from the central channel of the plasma. 相似文献
98.
Torsional wave dispersion and attenuation in an open empty welded pipe are determined from a multi-receiver position reflection experiment. The fundamental torsional wave is dominantly reflected at the free end and the converted non-axisymmetric flexural modes are naturally attenuated. The resulting phase velocity contours are in agreement with theoretical predictions. The transmission losses are quantified and compared to those reflective elements associated with end and weld reflection. At any reflective node, the incident wave is split between back and forward preserved mode scattering (“reflection/transmission”), conversion to other modes plus energy lost by absorption. The ratios for each element are quantified. 相似文献
99.
Slow crack growth behavior in polyethylene pipe grade resins were studied using both static fatigue (stress-rupture) and cyclic fatigue tests. This was done to better understand the applicability of cyclic fatigue in the prediction of slow crack growth ranking determined from the static fatigue test. In all polyethylene pipe grade resins tested at 80 °C, reduced crack growth failure times were exhibited when the cyclic fatigue test was employed. However, when applied to rank the resins through their slow crack failure times, the cyclic fatigue results did not always confirm those obtained from the static fatigue test. That is, in some cases, a resin with higher slow crack resistance ranking (longer failure times) than another resin in static fatigue exhibited lower ranking (shorter failure times) in the cyclic fatigue test. This abnormality of reversal in ranking is not a general observation but does occur. Based on the data obtained so far, when resins with smaller differences between static fatigue and cyclic fatigue slow crack growth failure times are compared with those resins having larger differences, the chances of correctly predicting the ranking obtained from static fatigue using cyclic fatigue tend to decrease. Hence, it is suggested that one needs to practice caution when using cyclic fatigue to predict the static fatigue ranking of resins for slow cracking resistance. Some insight into the cause of such abnormality is discussed with reference to creep-fatigue interactions. 相似文献
100.
Wound closure and healing have been a problem that humans have faced since the ancient eras. An appropriate tissue connector must hold the edges of injured tissues close together to support healing and also prevent the leakage of biological fluids when resisting against the tensile forces. Even though clinical usage of mechanical methods is convenient for wound closure, their application has some limitations and drawbacks such as being painful for patients and hard to apply for surgeons when the injured site is not in touch. Furthermore, they do not have desirable cosmetic results. To solve these problems, closing the wounds with sticky materials has been introduced to prevent bleeding and induce the wound healing process. To this regard, many types of surgical adhesives including tissue adhesives have been developed to be a suitable alternative for sutures and staples. There is also a new approach which aims at producing bioadhesives by mimicking the nature along with applying nanotechnology methods. Today, many studies have been done to develop new adhesives inspired by nature. We have attempted to introduce the fundamentals of wound healing along with the different types of bioadhesives, their properties, and clinical applications in a simple and illustrated comprehensive way. 相似文献