|
This paper describes the design of a frequency shifter to suppress acoustic feedback, to be studied by the experimental method. When the frequency shifter is inserted between the microphone and loudspeaker in the public address system, it shifts all frequency components of the microphone signal by a constant amount. By this method two types of distortions due to acoustic feedback in the public address system can be reduced. The sound pressure level in a room can be increased by about 5-8 db on a... This paper describes the design of a frequency shifter to suppress acoustic feedback, to be studied by the experimental method. When the frequency shifter is inserted between the microphone and loudspeaker in the public address system, it shifts all frequency components of the microphone signal by a constant amount. By this method two types of distortions due to acoustic feedback in the public address system can be reduced. The sound pressure level in a room can be increased by about 5-8 db on a number of auditoriums. For the public address system in free field, which has multiple loudspeakers, it also has the same effect. If the public address system is operated below but too close to the instability condition the frequency shifter can reduce effectively the interference of the regenerative reverberation. 本文叙述抑制声反馈的频移器的设计,并进行了实验研究.当语言扩声系统的传声器和扬声器之间插入频移器时,传声器信号的所有频率分量都偏移一个常量,这种方法可以减少语言扩声系统在有声反馈时产生的两类畸变.对于一般厅堂,扩声声级大约可提高5—8分贝.对于具有分布式扬声器的窒外扩声系统,也有类似的效应.若语言扩声系统临近不稳定状态工作,频移器可以有效地减少再生混响干扰. Usually, the construction of mosaic plate is used in the public display installations, and there are a lot of plasma display units in it. For the purpose of lowering cost for the display panel, it is suggested to use Pb-Cd low-melting-point glass as dielectric instead of MgO protective layer. In this paper, the aging characteristics of the new dielectric are discussed. In comparison with the common lead-rich glass, it possesses better sputtering-resistant property, thus its firing voltage changes slower... Usually, the construction of mosaic plate is used in the public display installations, and there are a lot of plasma display units in it. For the purpose of lowering cost for the display panel, it is suggested to use Pb-Cd low-melting-point glass as dielectric instead of MgO protective layer. In this paper, the aging characteristics of the new dielectric are discussed. In comparison with the common lead-rich glass, it possesses better sputtering-resistant property, thus its firing voltage changes slower with the operating time. The life of the plasma display panel so constructed exceeds 10,000 hours. 本文簡要地讨论了AC等离子体显示器件的老化机理,阐述了用氧化镉部分取代富铅玻璃中的氧化铅,制成铅镉低熔点玻璃电介质,并测量了与它有关的特性参数,认定此种玻璃介质材料比较适用于制作大型或超大型AC等离子体显示器件。 A new species of yeast——Sterigmatorayces fuzhouensis Yue was isolated from flower of mango in the public park of Fuzhou, Fujian province in 1978. The number of the sterimata (1—12 or more) is more than that in the other species. The daughter cell separates from the mother cell at the position near the end of the sterigma on the mother cell. The conidium is often pear-shaped or bottle-shaped just after separation. The streak on malt agar is cream colored, pasty, with a dry, dull and wrinkled surface. True... A new species of yeast——Sterigmatorayces fuzhouensis Yue was isolated from flower of mango in the public park of Fuzhou, Fujian province in 1978. The number of the sterimata (1—12 or more) is more than that in the other species. The daughter cell separates from the mother cell at the position near the end of the sterigma on the mother cell. The conidium is often pear-shaped or bottle-shaped just after separation. The streak on malt agar is cream colored, pasty, with a dry, dull and wrinkled surface. True mycelium presents in Dalmau plate cultures on corn meal agar. Occasionally septa can be found on mycelium. Single or clustered blastoconidia present on hypha and are similar to the mycotorula type of pseudomycelium. The present strain assimilates glucose, maltose, galactose, sucrose, lactose, raffinose, melibiose, sorbose, cellobiose, xylose, L-arabinose, D-arabinose, rhamnose, trehalose, ribose, ribitol, glucitol, galactitol, inositol, mannitol, erythritol, glycerol, ethanol, citric acid, and salicin cut not melezitose, α-methyl-D-glucoside, and lactic acid. Assimilation of potassium nitrate is in the negative. Since the strain we isolated differs from all hitherto described Sterigmatomyces species in either morphology or physiology, it is here considered as a new species. The diagnosis of the genus is extended to include the character of blastoconidium formation. A key to the genus has been given. The type culture is deposited in the Institute of Microbiology, Academia Sinica. 作者于1978年从福建省福州市西湖公园的芒果花中分离出一株酵母1519。该菌株不产生子囊孢子、掷孢子,亦未见到有锁状连合。未发现有性繁殖。无性繁殖是在母细胞上产生小梗,小梗上产生子细胞,子细胞还可再生小梗再生子细胞。如果子细胞不脱落则成链状或分枝的链状。不发酵任何糖。按照形态和繁殖特征只符合Lodder(1970)酵母分类专著中半知菌部分的梗孢酵母。因此将它放入梗孢酵母属,命名为福州梗孢酵母(Sterigmatomyces fuzhouensis sp.n.)。
|