浅谈西安地铁二号线正线信号电源系统

地铁信号系统是控稍列车安全运行的装置，电源设备是保证信号系统正常运行的可靠保证。地铁电源系统包括信号电源屏．UPS（不间断电源）及蓄电池，向信号设备提供所需种类的稳定电源。文中主要针对信号电源屏、UPS原理进行分析，提出了西安地铁正线信号系统电源设备的配置方案。     

磁饱和稳压信号电源屏的使用与维护

铁路信号电源屏是铁路信号控制系统的心脏 ,电源的稳定与否直接关系到铁路行车安全。在采用接触网供电的车站 ,由于机车启动时造成的网压波动范围大 ,实际有时下降 2 5 %～30 %(16 5Ｖ～ 15 4Ｖ) ,供电臂末端车站甚至更低 ,严重影响信号设备的正常使用 ,所以解决稳压问题是电源屏的首要问题。磁饱和电源屏由于稳压范围宽 ,精度高 ,输出短路保护 ,抗干扰性强等特点 ,在一定程度上改善和提高了供电质量 ,逐步在铁路信号供电系统中得到了广泛使用。1　磁饱和稳压信号电源屏的原理及特点电源屏稳压部分采用了磁合成交流稳压技术 ,使输出绕组所在…     

试论铁路信号电源屏可靠性的改进措施

本文分析了目前信号电源屏存在的一些问题,同时提出了一些改进措施和建议,并对未来发展方向提出了一些设想。     

铁路信号智能电源屏运用典型问题分析

针对近年来铁路信号智能电源屏运用中影响稳定的突出问题，从结构特点、理论技术、使用维护等方面进行了分析，并结合现场运用实际列举并分析了采取的整治措施。     

基于Borland C++ Builder 6.0的工装测试系统的设计和实现

本文介绍了某铁路电源屏模块所用PCB板的检测系统。通过采用多线程技术,做到了整个检测过程的自动进行和测试结果的自动保存,大大提高了检测效率。系统上层软件部分采用Borland C Builder 6.0进行设计,具有友好的使用界面和人性化的操作提示。     

25HZ铁磁分频器的温升解决措施

在现场使用的25HZ轨道电源屏中发现铁磁分频器温升过高、噪音大等现象。通过调查分析,制定了相应对策,并通过现场实施,达到了预期效果,提高了设备运用效率。     

提速电源屏相序监督报警电路的改进

介绍了提速电源屏电源相序的监督电路,实现对电源相序的监督并及时报警和故障的判断,从而,提出了电源相序的监督并报警的改进方法。     

便携式直流绝缘监察装置的研发及应用

直流系统的工作可靠性直接影响电力系统的安全稳定。因此,需要对直流电源绝缘情况进行实时监测,故障时发出告警信号。本文提出一种直流绝缘监察装置,包括RC钳制接地电路、A/D采样MCU数据处理器、检查比较声光报警电路和DC-DC电源。装置具有抗干扰能力强,体积小,使用方便等特点,特别适合短期工作,用于试验电源屏直流系统,能够及时有效发现直流绝缘故障,提高直流系统运行的可靠性。     

二次调制信号与PSK类信号的自动盲识别算法

研究了卫星通信中常用的二次调制信号和PSK类信号的自动盲识别算法。从信号时域和频域出发,提取了能反映调制方式差异的瞬时特征,并对这些特征进行了理论分析。在区分非恒包络信号时,引入了自相关处理,改进后瞬时幅度包络特征差异更加明显,在对二次调制信号进行识别时,引入了FM盲解调用于恢复内调制信号,内调制PSK信号的识别采用基于谱线特征的识别算法。最后通过计算机仿真验证了其识别性能,在信噪比不低于4 dB时,对信号集内的信号识别率达到90%以上。     

基于PFRFT周期积累的多相编码信号检测与参数估计

由于多相编码信号存在明显的周期时频分布规律性,在研究该类信号在低信噪比下的检测及参数估计问题时,对分数阶傅里叶变换进行周期延拓,首先结合该类信号的PWVD时频特性,通过分析多相编码信号的PWVD脊线分布特点与多分量LFM信号的关联特性,利用PFRFT对信号平行脊线能量进行积累,再根据积累后的峰值搜索对信号进行参数估计,最后采用与同样参数LFM信号进行RWT后的峰值固定比例结论对检测概率与参数估计精度进行分析。实验证明,该方法不仅成功提高了低信噪比下的多相码信号检测概率,而且五大参数的估计精度也得到了提高。     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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-