无线电发射设备测试中的不确定度分析

对无线电设备测试时的不确定进行研究,通过介绍无线电发射设备测试中涉及到的一些误差计算和分析方法,同时结合一些常用的测量进行实例分析计算。     

160-Gb/s NRZ-DQPSK optical transmission system employing QC-LDPC code

A quasi-cyclic low-density parity check （QC-LDPC） code is constructed by an improved stability of the shortest cycle algorithm for 160-Gb/s non-return zero differential quadrature phase shift keying （NRZ- DQPSK） optical transmission system with the fiber-based optical parametric amplifier （FOPA）. The QC- --14 d LDPC code with stability of the shortest cycle reduces the bit error ratio （BER） to 10 an restrains the error floor effectively.     

Ultra-high-speed single red–green–blue light-emitting diode-based visible light communication system utilizing advanced modulation formats

We report a 3.75-Gb/s visible light communication(VLC) system thatusessingle-carrier frequency-domain equalization(SC-FDE) based on a single red–green–blue(RGB) light-emitting diode(LED),with the measured bit error rates(BERs) under a pre-forward-error-correction threshold of 3.8×10-3.The fundamental characteristics of an RGB-LED-based VLC system are measured.We also compare SC-FDE with OFDM in terms of peak-to-average power ratio and BER performance,which shows that SC-FDE outperforms the OFDM modulation scheme.     

A voltage-controlled chaotic oscillator based on carbon nanotube field-effect transistor for low-power embedded systems

This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented. The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.     

不可逆过程的有效能消耗率及不可逆度

本文从不可逆过程有效能消耗率分析出发,提出一种表征不可逆过程的新参数一不可逆度,定义为不可逆过程的总有效能消耗率与总输入或输出能流流率之比值;在提出热力系的势能概念和多种形态能量的有效能定义式的基础上,阐述了有效能消耗率方程,有效能消耗源强度,有效能消耗率最小原理,给出并比较了有效能消耗率与熵产率和(火积)耗散率的关系;有效能消耗率与过程的能流率量纲一致,克服了熵产率和(火积)耗散率与能流率量纲不一致的缺点;不可逆度的物理意义是不可逆过程有效能消耗系数或功耗系数,与热力循环效率互补.     

Characteristics of Entanglement Wave in Two Parallel Spin Chains

Based on the solvable spin-1/2 Heisenberg chain we demonstrate how two many-body systems are entangled due to their partial entanglement. The entanglement wave in the two spin chains displays a damped oscillation if the spin number is N 〉 3, and only propagates with a certain velocity depending on the coupling constant J. Moreover, the entanglement wave will be reflected on the other ends of the two spin chains. A simple scheme for transferring some special two-qubit states to other two distant qubits is also proposed.     

基于OpenCV的机场跑道异物检测系统设计与研究

机场跑道的异物对飞机起降过程的安全带来非常大的威胁,所以机场跑道的异物精确检测已经成为保障飞机飞行安全一个非常重大的问题。文章主要从软硬件两个部分来研究了机场跑道异物检测系统,主要包括了机场道路监控中心和应急中心两个服务平台,重点分析了采用Camshift目标跟踪算法并应用在系统中,从而实现了监控系统前景目标识别和多目标跟踪两大功能;最后在Windows系统下做了测试实验,以VS2008为实验环境,采用OpenCV函数库开发一款机场跑道异物监控系统;通过实验结果的分析,该软件系统可靠性高,运行稳定,满足了识别精确度高和跟踪实时可靠的要求,显示系统具有较高的检测精确机场跑道异物检测系统设计度,为机场跑道放入侵监测系统更深入的理论研究和进一步的实际应用提供了方便。     

低温液体管路输送中几个问题的分析

对低温液体传输过程中气体置换、预冷过程、竖直管道中间歇泉现象、盲支管填充时和阀门开启时的不稳定现象作了较详细分析,指出了其可能造成的危害,并提出了相应的解决方法。     

简评《实用磁路设计》

由王以贞编著的《实用磁路设计》一书已由天津科学技术出版社出版。 作者在天津电声器材厂从事扬声器的技术工作已经三十多年了。十年前曾在厂内讲授编写《扬声器概论》,在国内电声界有一定影响,其中有磁路设计的章节。1986年,东北工学院、辽宁机械工程学会举办“磁路设计讲座”,请作者主持。当时这个“磁路设计讲座”的讲义就是现在这本《实用磁路设计》的前身。