Molecular Dynamic Simulation for HMX/NTO Supramolecular Explosive

Based on the crystal engineering, six models of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)/3-nitro-1,2,4-triazol-5-one(NTO) supramolecular explosive were designed. The probable formation of HMX/NTO supramolecular explosive was investigated by the molecular dynamic (MD) method. Interaction between oxygen atoms in HMX and hydrogen atoms in NTO or between hydrogen atoms in HMX and oxygen atoms in NTO were studied by the radial distribution function (RDF). It shows that there are strong hydrogen bonds and Van Der Waals forces between HMX and NTO, in which the hydrogen bonds between oxygen atoms in the NTO and hydrogen atoms in HMX are the main host-guest interactions. The distributions of bond length, bond angle and dihedral angle were simulated by MD. It shows that the structure of HMX is seriously distorted. The binding energies and X-ray powder diffraction (XRD) patterns were calculated on the basis of the final HMX/NTO supramolecular structures. The results show that the binding energies of six supramolecular models are E binding (1 1 1-) >E binding (1 0 0)>E binding (0 2 0)>E binding (random)>E binding (1 0 2-)>Ebinding (0 1 1), and the XRD patterns of six supramolecular models are quite different from pure HMX or NTO. Based on the investigation for growth morphology, binding energies and RDF, the model of HMX supercell substituted by NTO along the (1 1 1-) surface of HMX is easier to form.     

最小均方误差检测器对扩频系统中窄带干扰的抑制性能分析

本文首先说明当码元间隔内的码片数目与扩频序列周期相等时,直接序列扩频(DSSS)系统中最小均方误差(MMSE)意义下的最优滤波器也是最小误码率意义下的最优滤波器,因而能很好地抑制大多数干扰样式。本文具体分析了最小均方误差检测器对音频干扰以及自回归干扰的抑制性能,给出了详细的推导过程以及结论。     

网络电话的发展对传统运营商的冲击

美国《商业周刊》一篇题为《电信混乱》报道,因特网正迅速改造电信行业。现在每个月有数十万美国人转向沃尼奇等新兴公司的以网络技术为基础的电话服务。1200亿美元的传统电话业务的收入正每年减少好几个百分点,而以网络技术为基础的电信服务收入2007年将达到67亿美元,2003年这个数字是2.81亿美元。意识到沃尼奇等新兴网络公司的威胁,美国电信巨头AT&T、时代华纳、斯普林特通信、MCI以及不少小贝尔公司纷纷宣布开展此项业务。面对网络电话迅猛发展的汹涌以及新的竞争态势,我国传统运营商该如何应对?     

数字电视地面广播系统的截止率求解

针对现有5种数字电视地面广播系统(ATSC,DVB,ISDB,ADTB-T,DMB-T),给出了AWGN信道和多径衰落信道下各系统的截止率性能,并进行了比较.     

一种提高Power VDMOSFET栅电荷性能的新结构

文章提出一种减小VDMOSFET栅电荷（Qg）的新结构，通过二维数值模拟：相对于常规VDMOSFET，该结构将栅电荷降低42．93％，器件优值（FOM=Qg＊Ron）降低37．05％。我们分析了新结构的主要特性，并与常规VD-MOSFET进行了比较和参数优化分析。     

家用变频空调器控制电路原理与维修技术

随着人民生活水平的提高，家用空调进入千家万户，但传统的空调能耗大，长期使用需要支付大量的电费，特别是能源日益紧张的今天，推广节能技术成为当务之急。在这种情况下，变频调速技术最近几年在我国得到了迅速发展，本文结合美的KFR-50LW/FBPY变频空调器，重点分析了家用变频空调器控制电路的基本原理和维修技术，对于工程技术人员快捷的维修变频空调器，家庭人员更好的用好变频空调，更好地满足人民日益增长的物质生活的需要，有着十分重要的意义。     

Prediction of Speech Quality Based on Resilient Backpropagation Artificial Neural Network

The paper presents a system for monitoring and assessment the speech quality in the IP telephony infrastructures using modular probes. The probes are placed at key nodes in the network where aggregating packet loss data. The system dynamically measures speech quality and results are collected on a central server. For data analysis we applied four-state Markov model for modeling the impact of network impairments on speech quality, afterwards, the resilient back propagation (Rprop) algorithm was used to train a neural network. Information about the speech quality are displayed in the form of automatically generated graphs and tables. The proposed solution has been tested with selected codecs and further generalizes the already presented concepts of the speech quality estimation in the IP environment.

     

Fatigue-Resistant Conducting Polymer Hydrogels as Strain Sensor for Underwater Robotics

Conducting polymer hydrogels are widely used as strain sensors in light of their distinct skin-like softness, strain sensitivity, and environmental adaptiveness in the fields of wearable devices, soft robots, and human-machine interface. However, the mechanical and electrical properties of existing conducting polymer hydrogels, especially fatigue-resistance and sensing robustness during long-term application, are unsatisfactory, which severely hamper their practical utilities. Herein, a strategy to fabricate conducting polymer hydrogels with anisotropic structures and mechanics is presented through a combined freeze-casting and salting-out process. The as-fabricated conducting polymer hydrogels exhibit high fatigue threshold (>300 J m⁻²), low Young's modulus (≈100 kPa), as well as long-term strain sensing robustness (over 10 000 cycles). Such superior performance enables their application as strain sensors to monitor the real-time movement of underwater robotics. The design and fabrication strategy for conducting polymer hydrogels reported in this study may open up an enticing avenue for functional soft materials in soft electronics and robotics.     

Correlated Quantum Phenomena of Spin–Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3 Based Artificial Superlattices

Unexpected, yet useful functionalities emerge when two or more materials merge coherently. Artificial oxide superlattices realize atomic and crystal structures that are not available in nature, thus providing controllable correlated quantum phenomena. This review focuses on 4d and 5d perovskite oxide superlattices, in which the spin–orbit coupling plays a significant role compared with conventional 3d oxide superlattices. Modulations in crystal structures with octahedral distortion, phonon engineering, electronic structures, spin orderings, and dimensionality control are discussed for 4d oxide superlattices. Atomic and magnetic structures, J_eff = 1/2 pseudospin and charge fluctuations, and the integration of topology and correlation are discussed for 5d oxide superlattices. This review provides insights into how correlated quantum phenomena arise from the deliberate design of superlattice structures that give birth to novel functionalities.     

An Apoptotic Body-based Vehicle with Navigation for Photothermal-Immunotherapy by Precise Delivery and Tumor Microenvironment Regulation

Tumor precision therapy and preventing tumor recurrence and metastasis are the main challenges to tumor eradication. Herein, an apoptotic body-based vehicle with imaging navigation is developed for precise tumor delivery and photothermal-immunotherapy by IR820-conjugated apoptotic body loaded with R848 nanoparticles. The apoptotic body serves as ammunition stores as well as vehicle drive engines, while IR820 acts as a fluorescence imaging navigation and photothermal controlling system. The apoptotic body vehicle can deliver the ammunition to tumor and achieve deep penetration by macrophage-hitchhiking. Fluorescence imaging navigation opens a control window for photothermal treatment, followed by photothermal triggering of in situ vaccine formation. Further, CD47 antibody loaded hydrogel strengthens innate and adaptive immunity, simultaneously the polarization of macrophages regulates the immunosuppressive microenvironment to further promote the combined antitumor immunotherapy. With breast tumor (4T1)-bearing mice model, the apoptotic body vehicle performs excellent therapeutic efficacy for primary tumor, distant tumor, tumor metastasis, and recurrence prevention.