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91.
A series of symmetrically thiophene-based bent-shaped molecules with branched terminal was synthesised and characterised. Then, their effects as dopants on the blue phase (BP) range of the chiral nematic liquid crystal (N*LC) host were investigated. It was found that the bent-shaped dopants with branched terminal had better miscibility in LC host than the bent-shaped dopants with straight terminal, and contributed to induce BP and enhance the BP temperature range, with the maximum BP temperature range about 20.4°C. Besides, the electro-optical (E-O) performances of the blue phase liquid crystal doped with Th-BC6 (a bent-shaped dopant with the widest induced BP range in N*LC) were also explored. It was found that the drive voltage reduced first and then increased with the doping amount of Th-BC6 increasing. When the doping amount of Th-BC6 was about 15 wt%, the hysteresis could be strikingly reduced. 相似文献
92.
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94.
Richard Miller 《Journal of voice》1996,10(2):109-128
Notated sacred solo song dates from 1,000 B.C. Early secular song exhibits modest vocal demands of chant-like character. Popular song and liturgical solo song share common origins. Western European secular song notation began in the early Medieval Age. Compositional writing for solo voice took a dramatic turn toward virtuosity about 1600. By the mid-17th century, the modern solo voice emerged. “Classical” solo vocal literature is not static but is constantly evolving, requiring skills far in excess of those of speech or of early solo song literature; this is equally the case with ethnomusicological and popular singing styles. Efficient use of the singing instrument is essential to the healthy accomplishment of all of these literatures. 相似文献
95.
Both a test rig and a method are presented for the indoor testing of vibration performances of road vehicle suspension systems.
A suspension (corner) has been positioned on a rotating drum (2.6 m diameter) placed in the Laboratory for the Safety of Transport
of the Politecnico di Milano. The suspension system is excited by means of cleats fixed to the working surface of the rotating
drum. The forces and the moments acting at the suspension-chassis joints are measured in the frequency range 0–120 Hz. Five
special six-axis load cells have been conceived, manufactured, calibrated and employed. Transient wheel motions have been
recorded. The influence of the vehicle speed on the relevant vibration performance indexes has been assessed. An approach
for the identification of the suspension damping characteristics is introduced. A full and accurate characterization of a
vehicle suspension system has been performed. 相似文献
96.
通过高温固相法制得尖晶石LiMn2O4,然后在通过简单易行的无水乙醇蒸干法包覆LaF3来修饰LiMn2O4。利用XRD,SEM来表征LaF3修饰的LiMn2O4的结构和形貌特征,并通过电化学测试研究LaF3修饰LiMn2O4的高温和常温下的电化学性能,另外结合电化学阻抗谱(EIS)和循环伏安(CV)考察表面修饰的锰酸锂的循环阻抗和循环可逆性。结果显示:经LaF3修饰过的LiMn2O4仍具有尖晶石结构,并且具有良好的电学性能。其中,以3wt%的修饰效果最好,常温循环100次和高温循环50次的循环保持率分别是91%和90%;而且,EIS和CV分别表明经LaF3修饰的LiMn2O4的电荷传递阻抗明显减小,其循环可逆性也明显提高。 相似文献
97.
Mg0.95Ni0.05TiO3 ceramics were prepared by traditional solid-state route using sintering temperatures between 1300 and 1425 °C and holding time of 2–8 h. The sintered samples were characterized for their phase composition, micro-crystalline structure, unit–cell constant, and dielectric properties. A two-phase combination region was identified over the entire compositional range. The effect of sintering conditions was analyzed for various properties. Both permittivity (εr) and Q factor (Qf) were sensitive to sintering temperatures and holding times, and the optimum performance was found at 1350 °C withholding time of 4 h. The temperature coefficient of resonant frequency (τf) in a range from −45.2 to −52 (ppm/°C) and unit–cell constant were not sensitive to both the sintering temperature and holding time. An optimized Q factor of 192,000 (GHz) related with a permittivity (εr) of 17.35 and a temperature coefficient (τf) of −47 (ppm/°C) was realized for the specimen sintered at 1350 °C withholding time of 4 h. For applications of 5G communication device (filter, antennas, etc.), Mg0.95Ni0.05TiO3 is considered to be a suitable candidate for substrate materials. 相似文献
98.
通过高温固相法制得尖晶石LiMn2O4,然后在通过简单易行的无水乙醇蒸干法包覆LaF3来修饰LiMn2O4。利用XRD,SEM来表征LaF3修饰的LiMn2O4的结构和形貌特征,并通过电化学测试研究LaF3修饰LiMn2O4的高温和常温下的电化学性能,另外结合电化学阻抗谱(EIS)和循环伏安(CV)考察表面修饰的锰酸锂的循环阻抗和循环可逆性。结果显示:经LaF3修饰过的LiMn2O4仍具有尖晶石结构,并且具有良好的电学性能。其中,以3wt%的修饰效果最好,常温循环100次和高温循环50次的循环保持率分别是91%和90%;而且,EIS和CV分别表明经LaF3修饰的LiMn2O4的电荷传递阻抗明显减小,其循环可逆性也明显提高。 相似文献
99.
Jennifer M. Oates Belinda Bain Pamela Davis Janice Chapman Dianna Kenny 《Journal of voice》2006,20(1):71-81
Although considerable progress has been made in the development of acoustic and physiological measures of operatic singing voice, there is still no widely accepted objective tool for the evaluation of its multidimensional features. Auditory-perceptual evaluation, therefore, remains an important evaluation method for singing pedagogues, voice scientists, and clinicians who work with opera singers. Few investigators, however, have attempted to develop standard auditory-perceptual tools for evaluation of the operatic voice. This study aimed to pilot test a new auditory-perceptual rating instrument for operatic singing voice. Nine expert teachers of operatic singing used the instrument to rate the singing voices of 21 professional opera chorus artists from a national opera company. The findings showed that the instrument has good face validity, that it can be legitimately treated as a psychometrically sound scale, and that raters can use the scale consistently, both between and within judges. This new instrument, therefore, has the potential to allow opera singers, their teachers, voice care clinicians, and researchers to evaluate the important auditory-perceptual features of operatic voice quality. 相似文献
100.