首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到17条相似文献,搜索用时 10 毫秒
1.
论述了1550 nm射频电视(CATV)通道与1490 nm数据通道的相互干扰问题。针对1490 nm光波通过光纤中受激拉曼效应对1550 nm光波的非线性串扰和1550 nm光波通过粗波分复用(CWDM)分波器对1490 nm光波的线性串扰提出了理论计算公式,进行了定量分析和计算。结果表明,数据非线性串扰可使射频电视系统低频端的载噪比下跌9 dB;而在常规融锥型粗波分复用分波器情况下,射频电视线性串扰可使数据光接收机的光功率代价达到2.5dB。最后指出了克服串扰的方法,如以太空闲字符扰码和高隔离度粗波分复用等。  相似文献   

2.
Implement of FEC in the Optical Transport Network   总被引:2,自引:0,他引:2  
Forward error correction (FEC) is a method by which extra information is included along with the original signal to provide redundancy for correcting bit errors. According to Reed Solomon code regularity, a certain amount of bit errors can be corrected. The appropriate capability of correcting burst bits in error may be more flexible implement of FEC in the optical transport network. The suitable choice can effectively reduce cost of the optical transport network.  相似文献   

3.
卫星内无线光网络通信技术及其实现   总被引:1,自引:8,他引:1  
蔡然  薛蔡  曹捷  傅劲  胡渝 《光子学报》2005,34(2):263-266
卫星内无线光网络通信的基础在于卫星内无线光通信链路. 为保障链路质量, 必须解决适合卫星内环境的抗噪和抗多径损害等技术问题, 以及相关设备的适当重量、体积和功耗等实现问题. 其关键是结合载波和卫星环境的特性, 并配合其它卫星技术研究无线光网络通信技术. 实验表明, 在卫星内实现适应编码调制和脉冲波形技术, 无线光噪声复合消除技术、后验均衡技术和有序捆绑解调解码技术等, 点对点和点对多点高速光链路误码率达到了正常通信要求. 为进一步利用无线光属性组建高服务质量(QoS)网络, 获得高的整体通信效率奠定坚实根基.  相似文献   

4.
The synchronous conditions of two kinds of the small-world (SW) network are studied. The small world topology can affect on dynamical behaviors of the beam transport network (BTN) largely, if the BTN is constructed with the SW topology, the global linear coupling and special linear feedback can realize the synchronization control of beam halo-chaos as well as periodic state in the BTN with the SW topology, respectively. This important result can provide an effective way for the experimental study and the engineering design of the BTN in the high-current accelerator driven radioactive clean nuclear power systems, and may have potential use in prospective applications for halo-chaos secure communication.  相似文献   

5.
大学物理演示实验网络教学管理平台构建与实施   总被引:1,自引:0,他引:1  
详细介绍了我校开发的“大学物理演示实验网络教学管理平台”的框架,其在教学管理中所发挥的作用,运行的效果,特别是在低年级本科生创新能力培养中所显现的效果.  相似文献   

6.
Abstract

Newly synthesized poly(azomethine urethanes) in thin films were deposited onto glass substrates from dimethylformamide solutions. Temperature dependences of the electrical conductivity and thermoelectric power were studied. The investigated polymers have interesting semiconductor characteristics. The values of important parameters of these films (activation energy of electrical conduction, charge carrier concentrations, and ratio of carrier mobilities) were calculated. The nature of the electrical conduction mechanism in the respective polymers is discussed. Transmission and absorption spectra were studied in the spectral domain, 300–1250 nm.  相似文献   

7.
In the present study, we investigated the influences of polymerization and crosslinking technologies on the branched-chain structures, crystallization behaviors, and gel networks of two types of low-density polyethylenes, LDPE1 and LDPE2, polymerized under different polymerization conditions in commercial large-capacity production lines. High temperature 13C NMR analysis suggests that the molar contents of both long-chain branches and short-chain branches of LDPE2 were markedly higher than those of LDPE1 due to a higher polymerization temperature for LDPE2. The high content of chain branches of LDPE2 leads to its relatively higher storage modulus, entanglement density, and gel content, as indicated by dynamic mechanical analysis. In addition, when the crosslinking temperature reached 180°C, the LDPE2 crosslinked with 2 wt% dicumylperoxide (XLPE2-D2) displayed a relatively wider processing time window and a faster crosslinking rate than XLPE1-D2. Successive self-nucleation and annealing fractionation indicated that increasing the concentration of dicumylperoxide can improve the crosslinking degree, but resulted in lower crystallinity and thinner lamellar crystals.  相似文献   

8.
新一代遥测网络系统(TmNS)包括试验对象端(TAS)和地面站端(GSS)两大部分,在对这两部分的功能结构,包括系统组成,各组成单元功能关系进行研究的基础上,依据飞行试验遥测传输需求,对新一代遥测网络系统的传输与组网方式进行研究分析。  相似文献   

9.
熊正良  徐东明 《应用声学》2016,24(6):223-225, 243
现有的不同厂家的SDH设备网管信息不能实现互通,为了解决这一问题,提出了一种SDH网管信息提取和插入系统的软硬件设计方案,主要包括网管信息的提取和插入、HDLC数据的封装和拆封、利用主控制器和USB模块进行数据传输,从而实现网管信息的高速上传并在上位机实时显示和保存功能。最后对该系统进行了测试验证,结果表明该系统能分析不同的SDH设备网管信息,为网管信息互通提供了基础信息。  相似文献   

10.
Abstract

Fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In the last decade, there has also been an enormous increase of user data visible in mobile systems. The importance of fiber-optical techniques within the fixed transmission/transport networks of mobile systems is therefore inevitably increasing. This article summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in second-generation networks.  相似文献   

11.
王宁  刘立人  梁丰 《光学学报》1996,16(6):763-767
介绍一种基于数学形态谱和二维矢量分类网络的模式识别体系。数学形态谱相对于图像平移和旋转不变。建立了光学二维矢量分类网络,利用光学逻辑操作和最大值网络的循环操作,得到与输入图像最佳匹配的模式。  相似文献   

12.
Abstract

A full-duplex link implementing alternative wired and wireless access for wavelength-division multiplexing passive optical network is proposed with the uniformed three-tone converged optical signal, which provides a wired or wireless downlink access signal alternatively and an uplink optical carrier. The uplink optical carrier reversed by the converged optical signal makes the hybrid optical node unit free from the optical source. The simulation results show that the full-duplex link with a 10-Gb/s 16-quadrature amplitude modulation (16-QAM) downstream and 5 Gb/s binary upstream can provide both wired access with a bit-error rate below 10?9 and radio-over-fiber-based wireless access with a bit-error rate below 10?7 over 40 km of fiber without an optical source and optical amplifier in the hybrid optical node unit.  相似文献   

13.
A newly discovered physical mechanism involving incoherent electron tunneling in layers of the protein ferritin that are found in catecholaminergic neurons (catecholaminergic neuron electron transport or CNET) is hypothesized to support communication between neurons. Recent tests further confirm that these ferritin layers can also perform a switching function (in addition to providing an electron tunneling mechanism) that could be associated with action selection in those neurons, consistent with earlier predictions based on CNET. While further testing would be needed to confirm the hypothesis that CNET allows groups of neurons to communicate and act as a switch for selecting one of the neurons in the group to assist in reaching action potential, this paper explains how that hypothesized behavior would be consistent with Integrated Information Theory (IIT), one of a number of consciousness theories (CTs). While the sheer number of CTs suggest that any one of them alone is not sufficient to explain consciousness, this paper demonstrates that CNET can provide a physical substrate and action selection mechanism that is consistent with IIT and which can also be applied to other CTs, such as to conform them into a single explanation of consciousness.  相似文献   

14.
The environmental control system (ECS) is one of the most important systems in the aircraft used to regulate the pressure, temperature and humidity of the air in the cabin. This study investigates the influences of different architectures on the thermal performance and network structure of ECS. The refrigeration and pressurization performances of ECS with four different architectures are analyzed and compared by the endoreversible thermodynamic analysis method, and their external and internal responses have also been discussed. The results show that the connection modes of the heat exchanger have minor effects on the performance of ECSs, but the influence of the air cycle machine is obvious. This study attempts to abstract the ECS as a network structure based on the graph theory, and use entropy in information theory for quantitative evaluation. The results provide a theoretical basis for the design of ECS and facilitate engineers to make reliable decisions.  相似文献   

15.
Objective: To examine the Cardiac Rehabilitation Gifu Network (CR-GNet) feasibility in managing diseases and assisting patients in attaining physical fitness, and its impact on long-term outcomes after acute coronary syndrome (ACS). Methods: In this prospective observational study, we enrolled 47 patients with ACS registered in the CR-GNet between February 2016 and September 2019. 37, 29, and 21 patients underwent follow-up assessments for exercise capacity (peak oxygen uptake) at 3 months, 6 months, and 1 year after discharge, respectively. Major adverse cardiac events (MACE) were compared with controls not registered in the CR-GNet. Results: The coronary risk factors, except blood pressure, improved at 3 and 6 months, and 1 year after discharge. These risk factors in each patient significantly reduced from 2.9 at admission to 1.6, 1.4, and 1.9 at 3 months, 6 months, and 1 year after discharge (p<0.05), respectively. Peak oxygen uptake was significantly higher at 3 months (17.5±4.9 ml/kg/min), 6 months (17.9±5.1 ml/kg/min), and 1 year (17.5±5.5 ml/kg/min) after discharge than that at discharge (14.7±3.6 ml/kg/min) (p<0.05). During follow-up, there was no significant difference; MACE did not occur in any patients in the CR-GNet but occurred in controls. Conclusion: CR-GNet is a feasible option for the long-term management of ACS patients.  相似文献   

16.
提出了一种新的荧光光谱特征提取与模式分类方法以提高激光诱导5-ALA-PpIX荧光光谱对早期结肠癌的诊断准确率。利用小波多尺度分析法提取荧光光谱特征量,对提取的特征量采用基于Rprop算法的BP神经网络进行模式分类。对20只DMH诱导的SD大鼠,12只诱导鼠的第二代鼠,8只正常SD大鼠,按25 mg·kg-1体重剂量尾静脉注射5-ALA溶液,150 min后利用波长为370 nm的钛宝石激光进行活体检测。对预处理后的504条荧光光谱,利用小波多尺度分析法提取12个特征量,BP神经网络将其分为正常组与非正常组(非典型增生、早癌和进展期癌),分类敏感性与特异性分别为98.91%和97.2%,非典型增生、早癌及进展期癌对正常组织的识别准确率分别为91.3%, 98.85%及98.79%。结果表明此方法不仅对早期结肠癌具有较高的诊断率,且更利于临床实时诊断。  相似文献   

17.
为实现地质样品中元素含量的准确预测,提出了基于主成分分析(PCA)的改进型BP神经网络模型。采用X荧光光谱法,对新疆西天山地质样品中Fe,Ti,V,Pb和Zn等元素进行测量,将得到的X荧光计数作为输入变量,应用该模型对未知地质样品中Fe和Ti元素进行定量预测。结果表明:主成分分析与改进型BP神经网络模型取得了较好的预测效果,预测结果与化学分析值的相对误差小于3%,为地质样品元素含量预测提供了一种新型有效的方法。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号