多径衰落信道下射频识别系统抗干扰技术

射频识别(RFID)系统通信环境由简单近距离的室内通信向复杂远距离的都市通信发展,在读写器和电子标签之间出现了由多径效应引起的带多普勒频移的瑞利衰落。针对 B 类标签信号在多径瑞利衰落信道中的传输进行系统建模与分析,并将正交频分复用(OFDM)系统引入以提高 RFID信号对信噪比的敏感度。仿真结果表明,标签信号在多径瑞利衰落信道中对信噪比变化不敏感,引入 OFDM后信号对信噪比的敏感度明显提高,RFID系统抗干扰能力得到增强。     

Characterization of Asphalt Fractions by NMR Spectroscopy

Abstract

Petroleum asphalt was separated into saturates, naphthalene aromatics, polar aromatics, and asphaltenes using the Corbett method. These asphalt fractions were characterized by H-1 and C-13 nuclear magnetic resonance spectroscopy (NMR). The spectra of saturates illustrate only traceable quantities of aromatic hydrogen and aromatic carbon. Naphthalene aromatics, polar aromatics, and asphaltenes all have broad bands in the aromatic regions of both H-1 and C-13 NMR spectra. These broad bands demonstrate the presence of polycondensed aromatic rings present in the structure of naphthalene aromatics, polar aromatics, and asphaltenes. Based on available literature, numerous NMR resonance bands are identified. The quantitative estimations for various kinds of protons and carbons in the asphalt fractions are compared.     

The Thermodynamic Modeling of Asphaltene Precipitation Equilibrium during the Natural Production of Crude Oil: The Role of Pressure and Temperature

Asphaltene precipitation is a sophisticated issue in the upstream oil industry, worldwide, and has detrimental effect on a verity of production processes; it damages the properties of the reservoir and causes an unfavorable and significant decrease in oil production. In spite of numerous studies to predict asphaltene behavior, the effect of temperature on asphaltene precipitation during pressure depletion at reservoir conditions is still obscure in the literature. In this study the PVT data as well as experimental data of asphaltene precipitation at reservoir conditions of an Iranian light oil samples is used, and the asphaltene precipitation and deposition envelops (APE and ADE) of the oil are developed using solid thermodynamic modeling.     

针对PMOS应用的TiN金属栅功函数调节

PMOS管需要金属栅的功函数接近硅的价带边,所以寻找到合适的方法调节TiN的功函数使之正向移动是金属栅工程的重点,也是难点。本文详细研究了TiN金属栅的厚度,栅介质沉积后退火,氧引入,以及N含量变化对TiN功函数的影响。发现随着TiN的厚度变厚,功函数会正向移动,但是在某一个厚度会达到饱和,另外,在少量氧气氛围下的栅介质沉积后退火,也能使功函数正向移动,而在TiN中引入氧元素,以及增大N的含量都会使TiN的功函数正向漂移。以上所述方法都能有效的调节TiN的功函数来适应PMOS的需要。     

FSK Modulation Scheme for High-Speed Optical Transmission

In this paper,we describe the generation,detection,and performance of frequency-shift keying (FSK) for high-speed optical transmission and label switching.A non-return-to-zero (NRZ) FSK signal is generated by using two continuous-wave (CW) lasers,one Mach-Zehnder modulator (MZM),and one Mach-Zehnder delay interferometer (MZDI).An RZ-FSK signal is generated by cascading a dual-arm MZM,which is driven by a sinusoidal voltage at half the bit rate.Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating (AWG) demultiplexer with balanced detection.We perform numerical simulation on two types of frequency modulation schemes using MZM or PM,and we determine the effect of frequency tone spacing (FTS) on the generated FSK signal.In the proposed scheme,a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying (DPSK),under varying dispersion management.The performance of an RZ-FSK signal in a 4 × 40 Gb/s WDM transmission system is discussed.We experiment on transparent wavelength conversion based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) and in a highly nonlinear dispersion shifted fiber (HNDSF) for a 40 Gb/s RZ-FSK signal.The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed.We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber (SMF) transmission link with matching dispersion compensating fiber (DCF),under the post-compensation management scheme.Because the frequency modulation format is orthogonal to intensity modulation and vector modulation (polarization shift keying),it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate.It can also be used in orthogonal label-switching as the modulation format for the payload or the label.As an example,we propose a simple orthogonal optical label switching technique based on 40 Gb/s FSK payload and 2.5 Gb/s intensity modulated (IM) label.     

An AWG based colorless WDM-PON with RZ-DPSK modulated downstream and re-modulation of DL signal for OOK upstream

We proposed an arrayed waveguide granting (AWG) based 10 Gbps full duplex wavelength division multiplexing passive optical network (WDM-PON) utilizing a retum-to-zero differential phase shift keying (R...     

The influence of lanthanum doping position in ultra-thin HfO2 films for high-k gate dielectrics

Lanthanum dopant positioning at HfO₂ ultra-thin films was achieved by the co-sputtering method. The physical properties of graded doping HfO₂/HfLaO/p-Si and HfLaO/HfO₂/p-Si structures after 850 °C postannealing were compared. The thickness of the monolayer was analyzed by X-ray reflectivity and confirmed by the multiple beam interference model. The HfO₂ and silicate phases were characterized by X-ray diffraction patterns. It is found that crystallization depends on the ratio of stacked film thicknesses, and the HfLaO/HfO₂/Si structure has more silicate formation at the interface than the HfO₂/HfLaO/Si structure. Metal-insulator-semiconductor capacitors were fabricated. The electrical properties including leakage current, conduction mechanism, flatband voltage shift, and barrier height were studied.     

数字图像几何变换的数据并行方法研究

针对SIMD计算机上的数字图像的几何变换问题,提出了一个新颖的基于阵列平移的数据并行实现方法。在此基础上,给出了数字图像几何变换的数据并行实现算法,并详细分析和讨论了算法的复杂性以及精度要求。     

Coding Schemes Incorporating Soft-Decision DPSK over HF Rayleigh Fading Channels

A soft-decision 8-DPSK modulation format is introducedin a concatenated coding scheme and the performance of the resultingsystem is evaluated over a slow Rayleigh fading HF ionospheric link inthe presence of Additive White Gaussian noise (AWGN). Well-known UngerboeckTCM techniques are used as inner codes and a Reed–Solomon blockcode as outer code. The coded/modulated signal is differentially encodedbefore transmission to combat random phase changes caused by the channel.Soft-decision demodulator's output is used as an input to a modifiedViterbi decoder that calculates the Euclidean distances of the receivedsignal from an 8-PSK constellation adapted to the signal's amplitudevariations. Block interleaving techniques are necessary to randomise longbursts of errors caused by the fading channel. Simulation results showthat significant coding gains are achieved with a minor bandwidth expansionover uncoded, diversity or other coded systems. Finally, theinteresting effects of interleaving on the performance of the proposedsystems are analysed.     

利用复制理论生成Reed—Muller码的方法

本文通过复制理论简单地生成Reed0-Muller码,并利用复制理论讨论了它的纠错,检错等相关问题,得到了两个简单实用具具有较高可靠性的检错,纠错译码算法。