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71.
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73.
The goal of this study was to determine if there are acoustical differences between male and female voices, and if there are, where exactly do these differences lie. Extended speech samples were used. The recorded readings of a text by 31 women and by 24 men were analyzed by means of the Long-term Spectrum (LTAS), extracting the amplitude values (in decibels) at intervals of 160 Hz over a range of 8 kHz. The results showed a significant difference between genders, as well as an interaction of gender and frequency level. The female voice showed greater levels of aspiration noise, located in the spectral regions corresponding to the third formant, which causes the female voice to have a more “breathy” quality than the male voice. The lower spectral tilt in the women's voices is another consequence of this presence of greater aspiration noise. 相似文献
74.
从菲涅尔-基尔霍夫衍射积分公式出发,运用边界元法数值计算了平凹腔平面镜均匀反射率时倾斜和未倾斜情况下基模的场强分布、相位分布和本征值,同时与高斯反射率平面镜在腔镜倾斜时的情况做了比较。研究表明,腔镜倾斜使激光场模式分布沿发生倾斜的方向向镜边缘偏移,而且在腔镜倾斜较严重时模式分布发生畸变,不再是对称的高斯分布,基模本征值随倾斜角增大而变小,光束远场分布变差。同等条件下,高斯反射率平凹腔腔镜倾斜对谐振腔引起的模畸变小于均匀反射率平凹腔,且基模光场及本征值随镜倾斜的变化关系稍不同于均匀反射率平凹腔。 相似文献
75.
提出了超高速摄影仪中弹性支撑转镜模态分析方法,利用有限元法对三面体铝合金转镜刚性支撑和弹性支撑情况下的一、二阶模态进行模拟,结果表明:电驱动转镜在转速工作范围内只有2个临界点,分别位于2.5×105~2.6×5 r/min和2.6×105~2.7×105 r/min处, 并且均为一阶弯曲振动,一阶模态振动发生在垂直平面内,二阶发生在水平平面内。将模拟结果与实测值进行了比较,发现假设转镜为弹性支撑与实测值吻合得较好。 相似文献
76.
The present work deals with the problem of determing the influence of pressure at the bearing entry on load capacity and on the position of the resultant of the pressure forces in the case of a plane slider bearing; this work shows how a centrally pivoted pad may be employed where a shaft is also to be rotated in the reverse direction.
Sommario Scopo del presente lavoro è quello di determinare l'influenza che la pressione in ingresso ha sulla capacità di carico e sul punto di applicazione della risultante delle forze di pressione nel caso di un accoppiamento piano lubrificato; viene inoltre messo in evidenza il fatto che un pattino orientabile con cerniera di articolazione posta in mezzeria possa funzionare correttamente.相似文献
77.
Crystals of GaN grown by molecular-beam epitaxi on (0001) sapphire show [0001] tilt boundaries of low and high angles (V. Potin et al., Physical Review B, 61, 5587 (2000)). The structure of these boundaries plays a role in the optoelectrical properties shown by this semiconductor. In this work we have studied the atomic structure of 7, 13 and 19 boundaries (in the coincidence side lattice notation) by means of atomic computer simulation using a modified version of the empirical Stillinger-Weber interatomic potential. For each boundary we studied the interface of lowest period and found the atomic structure of minimum energy by applying the method of quasidynamic relaxation. Special attention has been paid to the 13 where we have studied two different interfaces comparing our results with the experimental results obtained in a study of bicrystals of ZnO (A.N. Kiselev et al., Phil. Mag. A, 76, 633 (1997)). In these boundaries the atomic structure can be understood in terms of edge dislocations located along the boundary. The a edge dislocation in GaN has been studied with the same potential and the stable structures are presented here for comparison. 相似文献
78.
A surface crystallization phenomenon on bonding pads and wires of integrated circuit
chip is reported in this paper. Through a lot of experiments, an unknown failure
effect caused by mixed crystalline matter is revealed, whereas non-plasma fluorine
contamination cannot cause the failure of bonding pads. By experiments combined with
infrared spectroscopy analysis, the surface crystallization effect is studied. The
conclusion of the study can provide the guidance for IC fabrication, modelling and
analysis. 相似文献
79.
Vacuum deposited films of immiscible metal–metal systems can be applied as tribological coatings for plain bearings in high
performance diesel engines. These industrially manufactured coatings show higher lifetimes than conventional electroplated
coatings. For our investigations we used aluminum-tin coatings of 1 μm thickness on a glass substrate produced by sequential
deposition from two separate targets under working gas pressure of 0.4 Pa. The tough Al matrix takes high mechanical loads
and the soft inclusions of Sn act as solid lubricant. While Sn is deposited it migrates on the Al surface and grows as islands.
We characterized the conformation and the distribution of the Sn islands on the surface and to the interstitial area between
the islands with 3-D secondary ion mass spectroscopy (SIMS). The existence of a Sn layer between the islands (“wetting layer”)
has been detected by SIMS and verified by measurements with Auger electron spectroscopy (AES). 相似文献
80.
Experiments carried out during the last 50 years have elucidated the basic mechanism of the Biefeld-Brown effect. Recent research has focused on establishing design rules in order to maximize the lifting force resulting from this effect. For this purpose, a numerical estimation that takes the effect of altitude into account is needed. In the present contribution, the thrust due to Biefeld-Brown effect was computed by simulating the corona-discharge-induced electrohydrodynamic flow in a widely used high-voltage asymmetric capacitor with the major goal to elucidate the dependence of thrust on the altitude, pressure, temperature and humidity, respectively. Our numerical results reproduced the experimentally observed decrease of thrust with altitude and shown that this is a consequence of various competing effects. 相似文献