Influence of doping on the dynamical properties of III–V–N by Raman scattering, infrared absorption and model calculations

In the framework of a rigid-ion model and using realistic Greens function theory, we have studied systematically the influence of doping on the lattice dynamics of III–V-nitrides. Our theoretical analysis is based on a sound physical appeal for the perturbation caused by different dopants in compound semiconductors. After analyzing the dynamical behavior for two sets of impurities with closest masses occupying Ga- and As-sites in GaAs, we have proposed simple empirical relationships providing corrections to the impurity–host interactions for isoelectronic defects and for dopants carrying static charges. Despite the simplicity of perturbation models, our Greens function theory provided results in good agreement with the recent Fourier-transform infrared (FTIR) absorption data for the magnitude and splitting of N-isotopic shifts of localized vibrational modes in GaAs. With high-resolution FTIR spectroscopy, we strongly believe that the ¹⁴N_As-related broad local mode (471 cm⁻¹) in GaAs can be resolved into fine structures due to Ga-host isotopes. Theoretical results for the in-band modes of As_N in cubic gallium nitride are compared and discussed with the existing Raman data on molecular beam epitaxy (MBE) grown GaN layers on GaAs substrates, as well as on GaN samples intentionally doped with As.     

折射率非线性调制的双重光纤光栅特性

利用耦合模理论 ,系统分析了双重光纤光栅在折射率深度调制或非线性调制情况下的光谱特性。结果发现 ,在折射率非线性调制情况下 ,双重光纤光栅具有规则的多波长反射特性 ,同时 ,其反射光谱中的二次谐波也变得非常强 ,因此 ,它是一种实现多通道波分复用器、分插复用器及多波长激光器等的潜在技术。     

用于海洋浮标的多串口数据采集系统设计

针对海洋浮标的布放环境和使用情况,本文介绍了一种用于海洋浮标的多串口数据采集系统,能够满足多种类型海洋浮标的应用需求.     

An Instance-Learning-Based Intrusion-Detection System for Wireless Sensor Networks

This paper proposes an instance?learning?based intrusion?detection system (IL?IDS) for wireless sensor networks (WSNs). The goal of the proposed system is to detect routing attacks on a WSN. Taking an ...     

适用于计算机绘图的数据结构浅议

计算机绘图中的数据处理,图学者往往感到棘手。本文介绍一种方便可行的数据结构,并举例说明其应用。     

Failure Deformation and Stress Relaxation of Heated Egg White Gels

Stress-strain relationships were determined for heated egg white gels. Compressive strain at failure was independent of protein concentration, while stress at failure increased with protein concentration. Between the length ratios of 1.6 and 2.4 before and after compression, the heated egg white gels followed the Mooney Rivlin model. In stress relaxation, the asymptotic hypothetical equilibrium modulus increased with protein concentration.     

电力系统混合优化的模拟进化方法

电力系统中有许多混合优化问题,采用常用方法求解难以奏效,而模拟进化方法是一种新型有效的优化方法,文中提出模拟进化方法中处理混合优化问题的两种办法,即离散变量连续化及连续变量离散化,并将其应用电力系统功率,电容器组的优化问题,结果表明所提方法是可行的。     

New Progress in Dam Monitoring Automation

Sincethethirddecadeofthiscentury,alongsidethedevelopingofdambuildinginmanycountries,thedamprototypeobservationhasmadeacorrespondingprogress.Differentkindsofembeddedinstrumentsuchasstrainmeter,thermometer,weredevelopedtoverifythedesign.Thedisasterofsomefamousdamsin5O'sand6o'smadepeopletoputmuchmoreattentionstodamsafety,strengthenedthemoredirectandeffectivemonitoringitemsofdamsafety,suchasdeformation,leakage,piezometry,andnewobservationinstrumentsaspenduline,tensileline,upliftcellwereadopted.Sin…     

延河泉水源地水资源评价

依据延河泉泉域和泉区水文地质条件,计算延河泉流量,并建立二维泉域数学模型,计算上游水源地开采后对延河泉流量的削减值,从而评价延河泉的B级允许开采量。     

220kV长电缆—GIS系统雷电侵入波计算分析

从分析计算得出２２０ｋＶ长电缆－ＧＩＳ系统雷电侵入波保护特性,并讨论了迁电压的因素,为变电站防雷设计提供了参考依据。