Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.     

音频分类中的特征分析

音频特征分析是音频分类的基础,分析了不同类音频的八个区别性特征,提出了修正低能量成分比率MLER和修正基频MPF两个新特征.综合考察了本文构造的不同特征集在可分性判据J下的分类性能.实验结果表明,提取的音频特征有效、合理,分类性能较好.     

Stochastic Resonance in a Time-Delayed Mono-Stable System with Multiplicative and Additive Noise

The stochastic resonance （SR） in a time-delayed mono-stable system driven by multiplicative white noise, additive white noise, additive dichotomous noise as well as a periodic square-wave signal is considered from the view of the signal-to-noise ratio （SNR）. It is found that the SNR increases monotonically with the increase of the delay time. The SNR exhibits the SR behavior when it is plotted as a function of intensities of the noises, displaying the asymmetry of the dichotomous noise. The SNR varies non-monotonically with the increase of the system parameter and the amplitude of the input square-wave signal.     

Dynamical protection design with P-cycle parallel heuristic algorithm for optical networks

研究并总结了现有的各种自相似流量分析和预测的方法,同时采集局域网的动态流量数据,在此基础上生成自相似业务流.结合当今计算机界正在蓬勃发展中的并行计算,设计相关P圈配置并行算法,并将其应用到光网络的动态仿真中.     

温湿度传感器的原理及应用

介绍了温湿度传感器DHT90的主要特点、工作原理、典型应用实例及应用程序。     

A novel spectrum sensing scheme with sensing time optimization for energy-efficient CRSNs

Wireless Networks - The cognitive radio technology enables secondary users (SUs) to occupy licensed bands when primary users (PUs) are not occupy them. Spectrum sensing is a key technology for SUs...     

蒸汽锅炉与热水锅炉水中元素变化比较分析

以电感耦合等离子体-光学发射光谱法(ICP-OES)测定蒸汽锅炉与热水锅炉水中9种元素含量变化。方法的回收率在90.0%—02.6%之间,相对标准偏差0.87%—3.12%。实验证明锅炉进水中含量最高的元素是钙、钠和镁。经过蒸汽锅炉和热水锅炉处理后,水中的微量元素发生了显著变化,且蒸汽锅炉和热水锅炉中的水质也有一定的差异。     

An experimental 75 GHz gyrotron

An experimental 75 GHz gyrotron has been designed and manufactured in our research institute. There are two different types of tube operating at the TE₅₂₁ ^○ and TE₀₄₁ ^○ modes, respectively, and at the second harmonic. A laminar flow magnetron injection gun is used so that the velocity spread due to the space-charge effect is greatly reduced.     

Dipole bands in nucleus ~(139)Pm

High-spin states in nucleus 139Pm have been studied using the reaction 116Cd(27Al,4n)139Pm.Two dipole cascades have been found.Spin and parity assignments were based on the Directional Correlation of Oriented Nuclei(DCO) ratios and systematic behavior in neighboring odd-proton nuclei.The level structures of 139Pm are compared with those of the N =78 isotone 141Eu in which two dipole bands have been confirmed as magnetic rotational bands.The close similarity between them suggests that the dipole bands in 139...