PPLT倍频宽线宽掺镱双包层光纤放大激光

分别通过理论和实验研究了周期性极化的钽酸锂（PPLT）倍频宽线宽准连续掺镱双包层光纤放大激光.PPLT样品长为40 mm,极化周期为7.67 μm.基频光的中心波长为1064 nm,线宽约为6 nm.从基频光的光谱特性出发,利用超晶格倍频理论,解释了实验中获得的倍频温度与二次谐波功率之间的关系.在基频光的功率为2.2 W时,获得的宽线宽光纤激光倍频效率为1.8%.     

基于P-N结的太阳能电池伏安特性的分析与模拟

通过分析实际P-N结与理想模型之间的差别,建立了P-N结二极管及太阳能电池的数学模型;利用Matlab中的系统仿真模块库建立仿真模型,设置参量,求解模型方程并绘制了图形.对太阳能电池在一定光照下旁路电阻及串联电阻取不同数值时对其开路电压、短路电流及填充因子的影响做了模拟,并与实际测得的硅太阳能电池伏安特性进行了比较.模型分析与实验测量的结果表明:等效的旁路电阻和串联电阻分别影响电池的开路电压和短路电流.仿真结果与实验测量结果一致.     

A digital filtering scheme for SQUID based magnetocardiography

Considering the properties of slow change and quasi-periodicity of magnetocardiography (MCG) signal, we use an integrated technique of adaptive and low-pass filtering in dealing with two-channel MCG data measured by high $T_{\rm c}$ SQUIDs. The adaptive filter in the time domain is based on a noise feedback normalized least-mean-square (NLMS) algorithm, and the low-pass filter with a cutoff at 100Hz in the frequency domain characterized by Gaussian functions is combined with a notch at the power line frequency. In this way, both relevant and irrelevant noises in original MCG data are largely eliminated. The method may also be useful for other slowly varying quasi-periodical signals.     

Cardy-Verlinde Formula and Thermodynamics of Black Hole in Higher Dimensional Space-Time

In this paper we discuss thermodynamics parameters of black hole horizon and cosmological horizon in general high-dimensional space-time. We obtain that the entropy of a cosmological horizon can be described by the Cardy-Verlinde formula. However, the entropy of black hole horizon will be expressed in a form of the Cardy-Verlinde formula, if one adopts the methods given by Abbott and Deser to compute the mass of a black hole in general high-dimensional space-time. Through discussion, relation among various thermodynamics parameters of the black hole in general high-dimensional space-time is given. That is, differential formula of the first law of thermodynamics is obtained. Because we discuss the general high-dimensional space-time, our result has universality. PACS: 04.20.Dw, 97.60.Lf     

H原子与CO2分子碰撞的化学反应与能量转移

用时间分辨傅立叶红外发射光谱的方法对H原子与CO2分子的碰撞动力学进行了实验研究．用紫外激光光解的方法分别制备出三个不同平动能为174．7、241．0和306．2 kJ／mol的氢原子,并引发H CO2→OH CO反应．观察到了反应的产物,即振动激发的CO (v≤2)．同时也看到了在H原子与CO2分子的碰撞中发生高效的T- V能量转移．CO2的反对称伸缩模的最高振动能级为v=4．化学反应与能量转移的速率之比大约为10．     

Evaluating shielding effectiveness for reducing space radiation cancer risks

We discuss calculations of probability distribution functions (PDF) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPE). The PDFs are used in significance tests for evaluating the effectiveness of potential radiation shielding approaches. Uncertainties in risk coefficients determined from epidemiology data, dose and dose–rate reduction factors, quality factors, and physics models of radiation environments are considered in models of cancer risk PDFs. Competing mortality risks and functional correlations in radiation quality factor uncertainties are included in the calculations. We show that the cancer risk uncertainty, defined as the ratio of the upper value of 95% confidence interval (CI) to the point estimate is about 4-fold for lunar and Mars mission risk projections. For short-stay lunar missions (), SPEs present the most significant risk, however one that is mitigated effectively by shielding, especially for carbon composites structures with high hydrogen content. In contrast, for long duration lunar () or Mars missions, GCR risks may exceed radiation risk limits that are based on acceptable levels of risk. For example, the upper 95% CI exceeding 10% fatal risk for males and females on a Mars mission. For reducing GCR cancer risks, shielding materials are marginally effective because of the penetrating nature of GCR and secondary radiation produced in tissue by relativistic particles. At the present time, polyethylene or carbon composite shielding cannot be shown to significantly reduce risk compared to aluminum shielding based on a significance test that accounts for radiobiology uncertainties in GCR risk projection.     

F+H2→HF+H反应的全量子态分辨的散射动力学研究

利用高灵敏度的氢原子里德堡飞渡时间谱方法研究了 F H_2→HF H 反应碰撞能在5.02kJ/mol 下的交叉分子束反应态态散射动力学.所有在时间飞渡谱中被观测到的谱峰可以归属为 HF 产物的振转态结构.还观测到了明显的 HF(v’=3)前向散射,以及少许的 HF(v’=2)前向散射.     

对等网络应用中的网络统计特征分析

本文基于实测数据抽象出用户网络与资源网络,探讨了对等网络中用户、资源及其内部的相互作用关系,发掘并分析了其内在的网络统计特征. 分析结果表明,用户节点度值及权值呈分段分布,体现了其各异的活跃性;网络资源的流行度差异明显,度值和权值近似呈幂律分布. 用户网络与资源网络存在分簇结构,少数簇中含大量节点,多数簇所含节点数量较少. 用户网络中,同簇内的用户有着相似的兴趣趋向,不同簇用户间兴趣趋向存在着差异,资源网络各簇中不同类别的资源间呈现出明显的关联性.     

铕与4-(4-吡啶甲酰基)苯甲酸配合物的合成与荧光性能研究

以Eu3+为中心离子,4-(4-吡啶甲酰基)苯甲酸(HPFBA)、1,10-菲罗啉(Phen)和三苯基氧膦(TPPO)为配体,合成了新型配合物Eu(PFBA)3(H2O)4,Eu(PFBA)3Phen(H2O)3和Eu(PFBA)3TPPO(H2O)3(PFBA=4-(4-吡啶甲酰基)苯甲酸根).红外光谱表明,形成配合...     

Fractional scanned carbon dioxide laser induces collagen remodelling in murine dermis

Resurfacing using a fractional CO₂ laser shows an important promise in the therapy on photoaged skin. The present study investigated that fractional CO₂ laser with a special sequential scanned manner induced the collagen remodelling in murine dermis. The results showed that laser resulted in the improvement of elasticity and histology in the murine dermis, meaning laser efficacy depends on both of the collagen formation and organization. We further investigated the relations between skin elasticity and type I, and type III collagen. These data demonstrated that laser could significantly lead to the collagen remodelling in murine dermis and induce neocollagenisis as a mode of resurfacing.