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921.
We describe one convenient synthesis route to boron nitride (BN) nanotube by the reaction of boron powder, iron oxide, and ammonium chloride at 600 °C for 12 h. Characterized by XRD, FTIR, XPS, TEM and SAED, the composition and morphology of the products are confirmed. The possible reaction mechanism is also discussed. 相似文献
922.
纬向对称准地转流的非线性稳定性定理 总被引:4,自引:0,他引:4
建立了周期域上准地转流在一般的边界条件下对应于Arnold第二定理的非线性稳定性定理。将扰动能量与扰动拟能的上界用初始扰动场的显示表示出来,从而建立了Liapunov意义下的非线性稳定性定理。 相似文献
923.
Xiaojing Huang Yunxin Li 《Communications, IEEE Transactions on》2005,53(7):1166-1177
The optimal linear modulation approximation of any M-ary continuous-phase modulated (CPM) signal under the minimum mean-square error (MMSE) criterion is presented in this paper. With the introduction of the MMSE signal component, an M-ary CPM signal is exactly represented as the superposition of a finite number of MMSE incremental pulses, resulting in the novel switched linear modulation CPM signal models. Then, the MMSE incremental pulse is further decomposed into a finite number of MMSE pulse-amplitude modulated (PAM) pulses, so that an M-ary CPM signal is alternatively expressed as the superposition of a finite number of MMSE PAM components, similar to the Laurent representation. Advantageously, these MMSE PAM components are mutually independent for any modulation index. The optimal CPM signal approximation using lower order MMSE incremental pulses, or alternatively, using a small number of MMSE PAM pulses, is also made possible, since the approximation error is minimized in the MMSE sense. Finally, examples of the MMSE-optimal CPM signal approximation and its comparison with the Laurent approximation approach are given using raised-cosine frequency-pulse CPM schemes. 相似文献
924.
925.
多信道E1映射复用成帧芯片PM8316及其应用 总被引:1,自引:0,他引:1
PM8316是PMC-Sierra公司生产的一种低功耗、高性能的多信道E1映射复用成帧芯片。该芯片内部集成了映射器、复用器、成帧器,其处理容量为63路E1,并含有8位微处理器总线接口和5个标准信号的JTAG测试端口,可支持收发抖动衰减。文中介绍了PM8316的主要功能和接口,给出了它在SDH终端设备中的主要信号电路框图。 相似文献
926.
MouseWarrior是德国CodeMercenaries公司生产的鼠标控制系列芯片。该芯片融合了所有的鼠标接口并集目前市场上所采用的新技术于一身,兼容性好且使用简单,是开发鼠标产品的理想选择。文中介绍了MouseWarrior系列芯片的性能特点和引脚功能,给出了一个鼠标电路的设计实例。 相似文献
927.
ZhengBin Zhang Chunying Liu Peifeng Li Zhenzhen Wu Cai Lin Huawei Huang Lei Xing Liansheng Liu 《Frontiers of Chemistry in China》2006,1(1):86-97
Many food algae and red tide algae were cultivated in the f/2 medium, and the nitric oxide (NO) concentration of the medium
and the cell density were determined. The experiments on algae were conducted when different concentrations of NO were added
into the medium using two methods. The results show that low concentrations of NO were self-produced by marine algae during
the exponential growth period and were about nmol/L level. But at the end of the period, i.e., 2 or 3 days before the cell
density reaches the maximum, an NO peak appeared, with the NO concentration reaching 10 nmol/L. The NO threshold concentration
exists according to the influence of exogenous NO on the marine phytoplankton growth. One type is the threshold concentration
that can promote algae growth, and its value is between 10 and 1 nmol level, or even lower. The other type can inhibit the
phytoplankton growth, which is about μmol level or higher. The results indicate that red tide algae are far more sensitive
to NO than are food algae. The fundamental experimental outcome above may provide a new clue for red tide chemical forecast
by inspecting the NO change. 相似文献
928.
The reference [4] proved the consistency of S1 and S2 among Lewis' five strict implication systems in the modal logic by using the method of the Boolean-valued model. But, in this method, the consistency of S3, S4 and S5 in Lewis' five strict implication systems is not decided. This paper makes use of the properties: (1) the equivalence of the modal systems S3 and P3, S4 and P4; (2) the modal systems P3 and P4 all contained the modal axiom T(□p → p); (3) the modal axiom T is correspondence to the reflexive property in VB. Hence, the paper proves: (a) ‖As31‖ = 1; (b) ‖AS41‖ = 1; (c) ‖AS5l‖ = 1 in the model (where B is a complete Boolean algebra, R is reflexive property in VB). Therefore, the paper finally proves that the Boolean-valued model VB of the ZFC axiom system in set theory is also a Boolean-valued model of Lewis' the strict implication system S3, S4 and S5. 相似文献
929.
本文讨论了在带有截断情况的线性回归模型中 ,响应变量均值的估计问题 .将经验似然的方法应用到带有截断情况的回归模型中 ,在估计响应变量的均值时构造了调整的经验似然统计量 ,证明了在一定的条件下 ,该统计量渐近服从 χ2 分布 ,给出了均值的置信区间 ,并与正态下得到的结果进行了比较 ,模拟的结果说明了经验似然的优良性 . 相似文献
930.