Phase-change regulation criterion based on size-dependent lattice distortion rate and born theory for VO2 nanomaterials

Vanadium dioxide (VO₂) is a promising thermally induced phase transition material because of the abrupt changes in electrical and optical properties. However, the high phase transition temperature of VO₂ and its unspecified modulation relationship need to be resolved urgently. Herein, we proposed a simple and precise regulation criterion for VO₂ materials based on size-dependent lattice distortion rate and Born theory. The results indicated that the application of a tensile stress changed the elastic properties of the VO₂, which promoted VO₂ phase transition, and regulated the phase transition temperature. Moreover, the specific modulation relationship between the stress and phase transition temperature of VO₂ was confirmed experimentally. These results show that our criterion provides theoretical guidance to regulate VO₂ thermally induced phase transition materials.     

全运村高清数字电视服务平台设计与应用

本文简要介绍了建设全运村高清数字电视平台的具体思路,以平台的实际需求为出发点,从组成结构、设计原则、设备配置和业务规划等方面,阐述了全运村高清数字电视平台的建设特点,从信源接收、转码以及复用加扰等多个方面探讨了平台的升级扩容能力,以及整个平台备份机制的实现和监控系统的组成,并介绍了系统的推广应用情况。     

无线语音发射系统的设计与实现

本文采用锁相环技术产生调频信号,设计了一款具有载波频率可调,频率稳定度高且失真小,采用普通收音机的调频波段即可接收的无线语音调频发射机。测试结果表明,各项指标均达到了设计要求,并且制作成本低。课题重点在于设计能给发射机调制电路提供稳定载波频率的锁相环电路。     

调质结构对Ti-TiN-Zr-ZrN多层膜力学性能影响

采用真空阴极电弧离子镀技术,在TC11钛合金和单晶Si片表面分别沉积不同调制周期、不同R_Ti/TiN:R_Zr/ZrN调制比和不同厚度的Ti-TiN-Zr-ZrN多层膜。用扫描电镜、X射线衍射仪、划痕仪、显微硬度计和应力测试仪分析测试了多层膜的截面形貌、厚度、结合力、硬度和残余应力;重点研究了调制周期、调制比和膜层厚度等调制结构的改变对多层膜残余应力和相关性能的影响。结果表明：增加调制周期,则残余应力降低,结合力和硬度均增大;降低RTi/TiN:RZr/ZrN调制比,则残余应力增大,结合力下降,硬度增加;增大多层膜厚度,则残余应力略有上升,结合力和硬度都提高,当膜层厚度达到7.54μm后,硬度稳定在30Gpa左右。     

Common Mode Voltage Reduction Using 3D-SVPWM for 3-level CI-NPC Inverter with Hybrid Energy System

This paper elucidates Common Mode Voltage (CMV) reduction in transformerless 3-phase 3-level Coupled Inductor Neutral Point (CI-NPC) Clamped Inverter with Hybrid Energy System. The three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) with Nearest State Vector (NSV) is implemented to reduce the CMV by proper selection of medium, large and small vectors in 3D cubic space region. This NSV scheme in addition to CMV reduction, reduces the capacitor voltage balancing issues and minimizes switching losses. The proposed control provides full utilization of dc link voltage with reduced harmonics. This 3-level CI-NPC inverter is energized by hybrid energy source which includes photovoltaic system and wind energy system. The results obtained for the proposed scheme through simulation and experimental setup is compared with the conventional 2D-SVPWM and 3D-SVPWM scheme. From the compared results it is evident that the proposed scheme reduces CMV to a larger extent than 2D and 3D-SVPWM control. The simulation and experimental results are verified using matlab-simulink and FPGA-Spartan-6 controller respectively.     

勒·柯布西耶的“Brise-Soleil”策略及其对当代建构学的 启示

本文通过对柯布“Brise-Soleil （遮阳）”的研究，考察建筑师如何结合 具体的气候环境，以呈现出特定的建构形 式表达，从环境调控和建构的角度阐述了 “ B r i s e -S ol e i l ”的意义。与此同时，指出 “Br ise-Solei l ”内在的一种关于建筑运行 机制的可读性——一种根植本土更为真实 而有效的建构价值，是非简单的形式与材料 /结构的二元关系所能涵盖的。     

Modulation instability in a dispersion oscillating fibre pumped by a broad band pulse

We numerically investigate the modulation instability generated in a dispersion oscillating fibre pumped by a chirped pulse with a broad bandwidth. We highlight that the side bands are wide, not symmetric in frequency about the pump and several instantaneous side bands can spectrally overlap with each other in one side, while they are well located in the other side. We also show that the spectral distribution can be intuitively explained with an analogy in which the fibre is pumped by a tuneable continuous wave.     

Adaptive modulation recognition based on the evolutionary algorithms

Nowadays, the development of classification algorithms gives the ability to improve Automatic Modulation Recognition (AMR) effectively. This paper presents a novel modulation recognition algorithm based on clustering approach. Generally, we aim to distinguish multicarrier modulation OFDM from single-carrier modulations. In this regard, two statistics of the amplitude of the received signal are calculated at the output of a quadrature mixer as key features. The extracted features of training data points are submitted to the clustering algorithm, then, centroids for single-carrier and multicarrier modulations are assessed. Afterwards, each point of testing dataset is dedicated to its nearest centroid based on Euclidian distance and the recognition is accomplished. Simulation results demonstrate that the algorithm is beneficial in a wide range from low to high SNRs.     

Thermal Effects and Small Signal Modulation of 1.3-μm InAs/GaAs Self-Assembled Quantum-Dot Lasers

We investigate the influence of thermal effects on the high-speed performance of 1.3-μm InAs/GaAs quantum-dot lasers in a wide temperature range (5–50°C). Ridge waveguide devices with 1.1 mm cavity length exhibit small signal modulation bandwidths of 7.51 GHz at 5°C and 3.98 GHz at 50°C. Temperature-dependent K-factor, differential gain, and gain compression factor are studied. While the intrinsic damping-limited modulation bandwidth is as high as 23 GHz, the actual modulation bandwidth is limited by carrier thermalization under continuous wave operation. Saturation of the resonance frequency was found to be the result of thermal reduction in the differential gain, which may originate from carrier thermalization.     

QAM signals recognition based on Amplitude distribution

In this paper, a Quadrature Amplitude Modulation (QAM) signal recognition algorithm is proposed based on amplitude distribution of the signal. The algorithm uses envelop amplitude dis-tribution information extracted by wavelet analysis to do modulation classification. It provides ro-bustness for symbol rate determination. Simulation shows that it is more effective and convenient than the recognition algorithm of likelihood function at moderate Signal-to-Noise Ratio (SNR).