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World Journal of Engineering and Technology 2024年第2期12卷 320-338页

作者： Taiyu Piao Xiaoan Hu College of Aircraft Power Engineering Nanchang Hangkong University Nanchang China

In the actual engineering of the structure, mechanical notch is inevitable, which will significantly reduce the fatigue life of the structure. In order to ensure the application of notch structures in engineering, the accurate evaluation of the impact of notch on fatigue life has become the basis of fatigue reliability design of structures. To investigate the influence of the concave structure on the overall fatigue life in practical engineering, three different sizes of V-notch parts and concave structure simulation parts were designed, and the life prediction was carried out by using the critical distance method. The results show that the stress gradient of the concave structure with the same stress concentration coefficient is much greater than that of the V-notch structure. Considering the notch effect, the S-T model in the critical distance method is modified by the stress concentration coefficient and stress gradient, and it is found that the life prediction accuracy reaches the ideal.

关键词： Notched Fatigue critical distance Stress Concentration Stress Gradient

Effects of flashing green on driver's stop/go decision at signalized intersection

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Journal of Central South University 2015年第2期22卷 771-778页

作者：沈家军王炜 College of Civil Science and Engineering Yangzhou University School of Transportation Southeast University

The primary objective of this work is to explore how drivers react to flashing green at signalized intersections. Through video taping and data procession based on photogrammetry, the operating speeds of vehicles before and after the moment when flashing green started was compared using paired-samples T-test. The critical distances between go and stop decisions was defined through cumulative percentage curve. The boundary of dilemma zone was determined by comparing stop distance and travel ***-running violation was analyzed on the basis of the travel time to the stop line. And finally, a logistic model for stop and go decisions was constructed. The results shows that the stopping ratios of the first vehicles of west-bound and east-bound approaches are 41.3% and 39.8%, respectively; the amber-light running violation ratios of two approaches are 31.6% and 25.4%, respectively;the operating speed growth ratios of first vehicles selecting to cross intersection after the moment when flashing green started are26.7% and 17.7%, respectively; and the critical distances are 48 m and 46 m, respectively, which are close to 44 m, the boundary of dilemma zone. The developed decision models demonstrate that the probability of go decision is higher when the distance from the stop line is shorter or operating speed is higher. This indicates that flashing green is an effective way to enhance intersection safety,but it should work together with a strict enforcement. In addition, traffic signs near critical distance and reasonable speed limitation are also beneficial to the safety of intersections.

关键词： signalized intersections flashing green critical distance dilemma zone amber-running violation logistic decision model

Deep Penetration of Spudcan Foundation into Double Layered Soils

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China Ocean Engineering 2005年第2期19卷 309-324页

作者：刘君胡玉霞孔宪京 State Key Loboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China Department of Civil Engineering Curtin University of TechnologyWestern Australia 6845 Australia

The spudcan foundation has been widely used in offshore engineering for jack-up rigs. However, “punch through' failure often occurs where a stronger soil layer overlays a softer soil layer. In this study, spudcan penetration into double layered soils is investigated numerically. The soil profile is set up as a stronger soil layer overlaying a softer soil layer, with the soil strength ratio (bottom soil strength / top soil strength) varied from 0.1 to 1.0 (1 means uniform soil). The bearing behaviour is discussed and the bearing capacity factors are given for various cases involving different layer thicknesses and different strength ratios of the two clay layers. The development of the plastic zones and the effect of soil self-weight on the bearing capacity are also discussed. From this study, it is found that, when a spudcan is distant from the soil layer boundary, the spudcan can be analysed with single soil layer data. However, when a spudcan becomes closer to the soil boundary layer, the influence of the lower soft soil layer is significant, and the bearing capacity of the spudcan decreases. The critical distance is an indication of the occurrence of “punch through' failure. The critical distance between the spudcan and the layer boundary is larger for a rough spudcan than the one for a smooth one, and the critical distance decreases with increasing soil strength ratio. The depth of cavity formed during initial spudcan penetration depends on the top layer soil strength, soil strength ratio and unit soil self-weight, and the cavity affects the spudcan bearing behaviour as well.

关键词： spudcan foundation punch through failure double layered soil critical distance continuous penetration

Spectral integration and perception of Chinese back vowel /γ/

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Science China(Information Sciences) 2010年第11期53卷 2300-2309页

作者： YU ShuiYuan1, CHEN YuDong2 & WU JieRu3 1School of Computer, Communication University of China, Beijing 100024, China 2International College for Chinese Language Studies, Communication University of China, Beijing 100024, China 3School of Presentation Art, Communication University of China, Beijing 100024, China School of Computer Communication University of China Beijing China International College for Chinese Language Studies Communication University of China Beijing China School of Presentation Art Communication University of China Beijing China

The first two formants of the back vowels of many languages, such as English, are often close in frequency within the critical 3.5-Bark distance and are phonetically equivalent to a single intermediate formant. This phenomenon is called spectral integration. The integrated spectral peak is related more directly to phonetic quality than to acoustic formants and is therefore an important cue for determining the phonetic quality of vowels. The Chinese vowel /γ/ is a back vowel, but its first two formants are commonly separated by more than the critical distance. What are the perceptual cues for this vowelDoes the spectral integration phenomenon influence its perceptionThis paper describes a series of identification experiments and rating experiments on the influences of the distance, spectral shape, and relative amplitude of the first two formants on the phonetic quality of /γ/. The results show that all stimuli with a two-peaked spectral shape are perceived as /γ/ whenever the first two formants are separated by the critical Bark distance or beyond. When the two formants are separated by roughly the critical distance, only those stimuli with sharp formants are perceived as /γ/, while stimuli with trapezoidal or single-peaked spectral shapes are not perceived as /γ/. Specifically, when the second formant is 10 dB higher than the first, the spectral integration phenomenon influences formant perception, and the stimulus is not perceived as /γ/; on the contrary, when the second formant is 0-20 dB lower than the first, the stimulus is perceived as /γ/, and spectral integration does not occur. That is to say, spectral integration occurs asymmetrically about the relative amplitudes of the first two formants. In a word, the Chinese vowel /γ/ is a back vowel, but spectral integration does not occur in the perception of its first two formants. Two individual formants are necessary for the phonetic color of the Chinese vowel /γ/. This vowel is different from the back vowels of w

关键词： spectral integration Chinese back vowel /γ/ back vowel critical distance

ADSORPTION OF NANO-PARTICLES ON BUBBLE SURFACE IN NANO-PARTICLE SUSPENSION

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China Particuology 2005年第4期3卷 208-212页

作者： Buxuan Wang Chunhui Li Xiaofeng Peng Laboratory of Phase-Change and Interfacial Transport Phenomena Department of Thermal Engineering Tsinghua UniversityBeijing 100084 P. R. China

The adsorption of nano-particles on bubble surface is discussed for saturated boiling on thin wire of nano-particle suspensions. Owing to the decrease of surface tension for suspensions, the nano-particles tend to adsorb on the bubble surface to decrease the Gibbs free energy for stability, and meanwhile the velocity of nano-particles would be smaller than that of bubble growth. The long-range van der Waals force existing between “water particles” and nano-particles is considered the attractive force between the nano-particles and the bubble surface. Thus, the nano-particles would attach on the bubble surface if the particle-surface distance is smaller than its critical value. The distribution of nano-particles on the bubble surface and in the adjacent region is also investigated.

关键词： nano-particle suspension attachment critical distance

Analyzing the Waveform of the Shunchang Earthquakes in Fujian Province

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Earthquake Research in China 2008年第4期22卷 383-390页

作者： Hong Xing Ye Wenyan Shao Pingrong Fanhquake Administration of Fujian Province Fuzhou 350003 China

On March 13,2007,two earthquakes with M4.7 and M4.6 occurred in Zhengfang Village,Shunchang,*** M4.7 earthquake is the most intensive one in the Fujian region since the establishment of the Fujian digital seismic *** two earthquakes provide us with valuable first-hand observation data for seismological *** paper analyzes their wave-forms and concludes that(1)the crustal thickness in the seismic region is estimated to be about 40km according to the observed head-wave critical distance;(2)there is a salient difference between the ratios of S-wave's maximum amplitudes of these two earthquakes;(3)the focal depth of the M4.7 earthquake is estimated to be 8.4km according to the clear depth phrase sPn in waveforms,which is the same with the result of other determination methods.

关键词： critical distance sPn phrase Focal depth