水下光通信PPM数字接收机的DSP实现

水下光通信充分利用了海水对激光的衰减窗口效应,具有隐蔽、安全、非接触和快速机动等特性,兼具无线通信和光纤通信的优点,其关键技术在于光收发端机的研制;PPM(Pulse Position Modulation)数字脉冲位置调制具有低平均功率和高峰值功率等特性,特别适合用于无线数字光通信。两者性能的融合需要高灵敏度数字光接收机的实现。利用阵列光电检测接收、高速A/D转换和信号处理等相关技术,采用DSP处理器,高灵敏度的数字光PPM接收机得以实现,实验和测试表明它大大降低了接收机对于整个系统信噪比的要求,获得了较好的性能。     

KNSBN晶体猫式互抽动相位共轭光特性

在KNSBN：Ce晶体中，利用二波耦合作用，在单一光束无法获得相位共轭光的条件下，实现了“猫”式互抽运相位共轭光输出，获得较高的共轭光发射率，实验结果表明，晶体的二波耦合作用可以使晶体的自抽运相位共轭光的阈值光强降低。入射光的入射角范围增大，响应时间缩短。     

Optical characteristics of semiconductor saturable absorber mirrors investigated by the reflection Z-scan technique

Recently, the semiconductor saturable absorber mirror (SESAM) has become a key component of passive mode-locked solid-state lasers. Here we present a simple method based on the reflection Z-scan technique to measure the key optical parameters of SESAM such as saturation fluence and modulation depth. The experimental results demonstrate that our method is able to perform with a high accuracy of 10⁻⁴ and a dynamic range of over four orders of magnitude.     

Lie Symmetry and Conserved Quantities for Nonholonomic Vacco Dynamical Systems

In this paper the Lie symmetry and conserved quantities for nonholonomic Vacco dynamical systems are studied. The determining equation of the Lie symmetry for the system is given. The general Hojman conserved quantity and the Lutzky conserved quantity deduced from the symmetry are obtained.     

Feature Selection using Fuzzy Support Vector Machines

The feature selection consists of obtaining a subset of these features to optimally realize the task without the irrelevant ones. Since it can provide faster and cost-effective learning machines and also improve the prediction performance of the predictors, it is a crucial step in machine learning. The feature selection methods using support machines have obtained satisfactory results, but the noises and outliers often reduce the performance. In this paper, we propose a feature selection approach using fuzzy support vector machines and compare it with the previous work, the results of experiments on the UCI data sets show that feature selection using fuzzy SVM obtains better results than using SVM.     

Pro-torus actions on Poincaré duality spaces

In this paper, it is shown that some of the results of torus actions on Poincaré duality spaces, Borel’s dimension formula and topological splitting principle to local weights, hold if ‘torus’ is replaced by ‘pro-torus’.     

Spectroscopic and Structural Study of the 1：2 Aluminium（Ⅲ） Complex of Quercetin

Complex formation between aluminium and quercetin（Q） in methanol was investigated by means of 27^Al solid-state, 13^C and 1^H NMR and MS（ESI）, UV and IR spectra. Formation of the 1：2 complex was favored in methanol relative to all other solvent and the predominant species observed of Al（Ⅲ） has a 1：2 stoichiometry. The fine structure of 1：2 aluminum complex of quercetin was that the aluminum central atom chelated with two quereetin molecules and two methoxyl groups between two five membered rings, its coordination is six, the chelated site was 3-hydroxy-4-carbonyl.     

Mn位W掺杂对La0.3Ca0.7MnO3体系磁结构的影响

通过对La0.3Ca0.7Mn1-xWxO3(x=0.00,0.04,0.08,0.12,0.15)多晶样品M-T曲线、M-H曲线及ESR谱的测量,研究了Mn位W掺杂对电荷有序体系La0.3Ca0.7MnO3磁结构的影响.结果表明,当掺杂量为0.00≤x≤0.08时,体系存在电荷有序(CO)相,AFM/CO态共存于相变温度以下,电荷有序温度TCO随着W掺杂量的增加而增加;x=0.04时,样品在低温下为FM相与AFM/CO相共存,在CO相建立前、后均有FM从PM中分离出来;当x≥0.12时,CO态融化,在极低温度下存在顺磁-铁磁(PM-FM)相变.     

Absorption Complex between Porphyrin and Phenothiazine in Reverse Micelles

Porphyrin derivatives attract much more interest in photodynamic therapy (PDT). Their importance as therapeutic drugs and targeting agents has been widely recognized1, and many of the efforts have been put towards crafting new porphyrin-based molecular entities to achieve enhanced tumor localization, better tissue penetration and increased singlet oxygen quantum yield2. The states of porphyrins in tissue models such as micelles, lipid bilayers are extensively investigated focusing more or l…