差动电容光纤传输差压计的研究

本文介绍了已研制出的一种以差动电容为敏感元件的传光型光纤差压传感器及其组成的光纤传输系统。该仪器的信号检测部分采用微功耗电子集成电路,压力信号用脉冲位置调制,这不仅使它适用于易燃易爆等特殊场合下的压力信号检测,而且也使它具有光纤传输所具有的高精度和高抗干扰能力。实验表明,当采用0～2000mmH~2O量程的敏感元件时,仪表精度优于1.5％,灵敏度达1mV/mmH_2O,示值稳定性小于0.3％。     

光子晶体光纤压力信号检测

光子晶体光纤具有压力敏感性.分析了光子晶体光纤中光信号传播时相位随外界压力变化的关系,提出了一种测量光子晶体光纤传输信号的自动化系统.光子晶体光纤可广泛用于光纤传感系统中.     

电场传感信号的光纤传输与智能测试

电场强度传感信号的传输和测试特别需要充分考虑系统对场分布的影响．在介绍电场传感信号的光纤传输和智能测试技术上重点讨论了系统的特点和设计思想，分析了电场传感信号的传输型光纤测试系统的原理以及以单片机为核心的智能信号处理方法。     

双向光纤多种业务传输系统

本文介绍了一种实用的光纤多种业务传输系统的组成和设计思想。该系统可以在一根光纤上同时传输一路视频信号、一路音频信号(兼对讲信号)和两路2.4kb/S数据信号,用两根光纤实现系统的双向多路传输。文中给出了设计指标和一些测试结果。     

光纤通信在自动控制设备中的应用

针对电气拖动自动控制设备中触发脉冲长距离传输中易受干扰的问题,根据光纤通信的基本工作原理,提出用光纤作为传输通道来解决,并设计出用１根光纤传输６路触发脉冲的两种不同光纤传输系统。同时根据自动控制设备中模拟信号和串行数字信号、开关信号在长距离传输中的抗干扰的问题及技术要求,设计出模拟信号光纤传输系统和串行数字信号光纤传输系统。     

一种脉位调制光纤传光式压力传感器的研究

介绍了微功耗压力传感器光纤耦合的原理以及使用单光纤传输双路信号进行比值测量的方法,讨论了这些措施对测量系统的稳定性,漂移,噪声抑制,抗干扰等性能指标的改善。     

分布式光纤传感系统相位还原的色散特性

在强度调制型光纤传感系统中,光脉冲的传播会受色散的影响而产生展宽效应.为了研究色散对相位调制型光纤传感系统相位传输特性的影响,本文对该系统获得的相位信号受色散的影响进行研究评估.该研究是基于宽光谱白光光源Sagnac结构的分布式光纤传感系统,分别使用正弦信号和脉冲信号对在不同长度传感光纤里传输的光进行相位调制,并还原出相应的相位调制信号;作为对比,在另一强度调制型光纤传感系统中,用相同参数的脉冲信号对在不同长度传感光纤里传输的光进行强度调制.结果显示,在强度调制型光纤传感系统中获得的脉冲信号会发生明显的展宽,但在相位调制型光纤传感系统中还原出的相位调制信号脉宽展宽明显小于强度调制型系统.     

光纤雷达传输系统试验成功

为了开发光纤的应用,了解光纤传输雷达信号的特点,我院通信研究所与720厂设计所共同进行了光纤雷达传输系统的试验,经过不到半年时间的努力,整个系统的试验工作已于最近完成。试验系统是用一根长度为1km、衰耗为7dB的光缆代替原有的四根100m同轴电缆,把796型导航雷达与带有计算机终端的616终端显示相连,传送796雷达送出的视频信号、触发脉冲、方位增量,正北信号。在终端显示器上动目标清楚,计算机录取正确,传输效果不低于原来的同轴电缆。试验表明,光纤是传输雷达信号的一种良好介质,与同轴电缆相比,不仅容量大、损耗小,而且具有较强的抗干扰、抗辐射能力,对雷达通信具有重要意义。此外,雷达具有多种信     

基于光子射频波高次倍频的深度融合通信研究

文中提出了基于光子射频高次倍频的微波与光纤深度融合的通信系统架构,从理论上论证了在已调制光信号中只存在奇数光谱边带所携带的调制信息,而偶数光谱边带不包含调制信息,并且在输出光谱边带中不存在二阶光谱边带. 在已调光信号传输到基站后,用中心光谱边带作为下行数据信号传输链路的激光光源,用分离出的低的第四阶光谱边带作为上行基带传输链路的激光光源,用高的和低的第三阶光谱边带拍频产生光子射频波. 通过专业仿真套件对25 km标准单模光纤传输的信号进行了模拟测试,分别得到下行光纤链路信号和上行光纤链路信号的清晰眼图和良好的误码率. 在该系统网络架构中,基站侧没有激光光源,其复杂度降低;利用光子射频波高次倍频直接产生毫米波,极大简化了射频处理单元.     

光纤雷达传输试验系统

本文叙述光纤传输雷达信号的试验及其结果,表明光纤系统适用于雷达信号的传输,并具有广阔的前景。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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