基于DMC发现算法的DMR控制策略实现

针对DLNA网络中多个DMC设备同时控制一个DMR设备容易出现运行混乱的情况,在兼容现有DLNA技术的基础上,通过分析DMC设备控制DMR设备的流程,指出DMR设备出现运行混乱的原因,提出一种发现网内DMC设备的算法并应用到DMR端,同时提出了三种DMR端的控制优化策略,解决DMR设备运行混乱的问题.实验结果表明,DMC发现算法与DMR控制策略的使用提高了DMC与DMR设备通信的可靠性与鲁棒性.     

基于DMR协议的数字对讲机中转模式设计

DMR协议是欧洲电信标准协会(ESTI)提出的专业数字通信协议。基于STM32、AMBE1000和收发芯片CC1120硬件平台,同时采用μC/OS-Ⅲ实时操作系统,设计了DMR协议中转模式,并对整个中转系统的运行和软件整体设计作了介绍。     

DMR标准RS码编译码器的FPGA实现

为了降低DMR标准Reed-Solomon（12,9）的译码复杂度,提出一种新的Step-by-Step译码算法。该算法通过计算伴随式,查找错误位置并同时计算修正子实现。与RS（255,239）和RS（255,249）相比,该算法不需要大量的存储器和复杂的逻辑控制,求逆运算也大为减少并且转化为有限域乘法器实现。该译码算法通过下载至Xilinx FPGA得到验证。     

DMR终端锁相调频接收机设计

DMR通信系统,是国际ETSI组织正在完善的最新专业数字移动通信标准.作为新一代数字通信系统DMR正在引起越来越多的重视,开发DMR数字终端设备也成为市场的迫切需求.本设计提出了一种由MAX2620、MB15E03组成的锁相环频率合成器提供本振,经过MAX2680和TA31136两次下变频,最后鉴频得到语音信号的接收机方案.本方案具有成本低、性能良好、接受灵敏度高、覆盖范围广等优点,并应用在已开发的DMR数字终端设备上.     

A New Design of Wide-Area MIMO Coupling Robust HVDC Supplementary Controller

A new multi-input multi-output (MIMO) robust coordination approach for the controller design of multi-infeed high voltage direct current (HVDC) system is proposed. This design will enhance the damping of certain low frequency oscillation mode. The dominant mode ratio (DMR) is applied to choose the appropriate feedback signals, while time delay of wide-area signals is considered. The Total Least Squares-Estimation on Signal Parameters via Rotational Technique (TLS-ESPRIT) algorithm serves in identifying the MIMO system model. To reach the best control effect and disturbance suppression level, the mixed H₂/H_∞ robust theory with regional poles placement is introduced to design the controller. The new MIMO design approach avoids system decoupling in complex situation, and it uses the interactions of different control loops to enhance the system's stability when most MIMO HVDC controllers are designed by decoupling strategy. Simulation results of a multi-infeed HVDC system validate the control effect and robustness of the proposed method.     

双混合制冷剂天然气液化过程实验分析

浮式天然气液化装置（LNG-FPSO）具有便于迁移、设备可靠、安全性高等特点,适应于海上油气田的开发。而混合制冷剂流程效率高、处理量大,在海况较平稳、气田产量大的条件下具有明显优势。利用与中海石油气电集团技术研发中心合作研制的浮式双混合制冷剂液化实验装置来验证双混合制冷剂流程的准确性,并对目标气田的原料气产量、原料气入口温度及压缩机频率等进行敏感性分析,以及海上适应性进行研究评价。通过实验发现双混合冷剂液化工艺可满足平稳海况下大规模天然气液化处理,原料气温度、压力在一定范围内变化对流程影响较小,采用变频式压缩机可有效降低低负荷下系统能耗。     

基于DMR标准的信道编解码研究

为了提高DMR系统基带算法的性能,分析研究了DMR标准中的3/4率网格码和二次剩余码。针对3/4率网格码,提出两种译码算法,方法 1充分利用了有限状态机的特性,方法 2将维特比译码算法中的蝶形运算进行推广改进。针对QR码,通过计算校验多项式的码重进行译码。MATLAB下的仿真结果表明,3/4率网格码的两种译码方法性能相差不大,但方法一的计算量少,易于工程实现。QR码的译码算法不仅有效地避免了计算复杂的错误位置多项式,而且提高了相同信噪比下的译码性能。     

中国南海FLNG液化技术与关键设备方案研究

浮式液化天然气生产储卸装置(LNG-FPSO,简称FLNG)是集海上天然气的液化、储存、装卸和外运为一体的新型FPSO装置。近十年来随着深海油气开发的推进,国内外掀起了FLNG研究、设计的高潮,FLNG也成为中国开发南海深水天然气的重要技术手段。本文针对我国南海深水天然气开发,研究并提出一套具有自主知识产权的200万吨级/年的FLNG上部液化技术与关键设备方案,包括:双塔双胺液循环新工艺;适用于FLNG的改进DMR液化工艺;冷剂压缩机驱动与发电采用定型航改燃机;预冷与液化深冷主换热器采用自行开发的FLNG铝制绕管换热器,具有安全可靠和高效易操作的技术优势。最后对推进我国南海FLNG工程化实施提出了两点建议:(1)加强FLNG铝制绕管换热器国产化研制和试验;(2)提高FLNG工程化实践能力。     

Syngas production from greenhouse gases using Ni–W bimetallic catalyst via dry methane reforming: Effect of W addition

DMR is a promising technique to utilize the rising greenhouse gases and produce an alternative energy source. The main hurdle in the commercialization of DMR is the catalyst deactivation. Presently, the effect of Tungsten (W) addition on Ni-based catalysts supported on mixed oxide (Al₂O₃–MgO) support is tested for DMR. The Ni–W bimetallic catalysts are synthesized via co-precipitation followed by the impregnation technique. An equimolar stream of feed (CH₄:CO₂) is used for DMR at 800 °C. The Ni–W catalyst with 4 wt% of W showed steady performance with elevated conversions of CH₄ and CO₂, even after 24 h of DMR. The freshly and spent catalysts are characterized by BET, XRD, FESEM, EDX, elemental mapping, TPR-H₂, TPD-CO₂, and XPS to confirm the elemental composition and the type of carbon formed on the catalysts. The activity of Ni catalyst declined due to formation of amorphous carbon-nanosheets, whereas Ni–W catalyst remained active due to formation of MWCNT.     

Study of the dry methane reforming process using a rotating gliding arc reactor

Dry methane reforming (DMR) via rotating gliding arc (RGA) discharge, co-driven by a magnetic field and tangential flow, was investigated in this study. Optical emission spectroscopy (OES) was used to characterize the major active species (energetic electrons, radicals, ions, atoms and excited molecules) in the DMR chemical process. The influence of the operational conditions (applied voltage and CH₄/CO₂ ratio) on the basic spectroscopic parameters (electron excitation temperature, electron density and rotational temperature) was determined by spectroscopic methods. The rotational and electron excitation temperatures were approximately 1100–1200 K and 1.1–1.7 eV, respectively, indicating the non-thermal equilibrium characteristics of the RGA discharge. The electron density was approximately 5–20 × 10²¹ m⁻³ by fitting the line shape of H_α at 656 nm. The conversions of the reactants (CH₄ and CO₂) and the selectivities of the products (H₂, CO and C₂ hydrocarbon) were analyzed using a gas chromatograph (GC) under different energy inputs or feed gas proportions. The structure and morphology of carbon black produced during the chemical process was characterized by high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy, indicating the properties of electrical conductivity and high absorption capacity that can be useful for potential application.