基于时间反演的室内精确单站定位技术研究

提出了一种基于时间反演和时域有限差分法的室内单站精确定位技术。该方法利用格林函数的对 称性和电磁互易定理以及室内多次反射形成的复杂信道实现单站定位。首先,在实景中接收传感器记录下室内任 意辐射源在接收点产生的场强信号,然后将该接收信号时间反演,在接收点进行辐射,此时在原辐射点形成信号的 相关聚集峰值,根据峰值位置实现单站无源精确定位。后一步的时间反演过程,如果发射信号已知,可以通过相关 运算来完成,如果信号形式未知,可以由时域有限差分法计算实现,无需构建真实的时间反演发射系统。仿真结果 表明:该算法能够利用多径效应,在室内复杂障碍物环境下实现λ /12= 8 cm 的定位精度,在室外也可以对室内目标 进行精确定位。     

一种基于时间反转法的超宽带通信系统

提出将时间反转法用于UWB系统,在发送端进行预滤波,并推导出符号间干扰和多用户干扰的封闭表达式。通过间隔概率的合并而得到的用户复用码具有跳时序列族的特征。采用IEEE 802.15.3a标准信道模型,将推导出的系统性能与仿真的跳时超宽带（ultra wide-band,UWB）系统的性能进行了比较,其中的跳时码采用Reed-Solomon。比较结果证明,仿真与推导的误码性能极其接近。     

新型中空玻璃密封胶的研制与应用

介绍新型中空玻璃用密封胶条-脱丙酮型室温硫化硅橡胶和聚硫橡胶的研制与应用，讨论和比较了这两种密封胶制造加工工艺以及性能方面的差异。进而对各自的不足提出了改善的方法。     

基于时间反演的到达时间定位

针对传统算法在室内超宽带（UWB）到达时间（TOA）定位系统里很难准确搜寻出第一条直射路径,从而导致定位精度不高的问题,提出了基于时间反演（TR）的TOA室内UWB定位算法。首先,利用TR处理的空时聚焦特性确定第一条直射路径,从而估计这条路径的TOA;其次,通过加权最小二乘（WLS）定位算法对不同的估计分量赋予相应的权值以提高定位精度。仿真结果表明,相较传统TOA定位,所提方案在低信噪比条件下的均方根误差（RMSE）减小了28.6%,可见该方案有效提升了系统定位精度。     

MPEG - 2 TS码流"健康检查"仪的研究与设计

在深入研究ISO/IEC 13818-1以及ISO/IEC 13818-4的基础上,并参考ESTI TR 101 290的规定,设计出在线实时检测MPEG-2 TS码流状态的"健康检查"(Health Check)仪.本文对设计"健康检查"仪的产业背景,"健康检查"仪的设计思路和方法都做了全面的论述,并以PCR精度检测为实例介绍设计的流程.     

Investigation of the chemical and morphological structure of thermally rearranged polymers

Reacting ortho-functional poly(hydroxyimide)s via a high-temperature (i.e., 350 °C–450 °C) solid-state reaction produces polymers with exceptional gas separation properties for separations such as CO₂/CH₄, CO₂/N₂, and H₂/CH₄. However, these reactions render these so-called thermally rearranged (TR) polymers insoluble in common solvents, which prevent the use of certain experimental characterization techniques such as solution-state nuclear magnetic resonance (NMR) from identifying their chemical structure. In this work, we seek to identify the chemical structure of TR polymers by synthesizing a partially soluble TR polymer from an ortho-functional poly(hydroxyamide). The chemical structure of this TR polymer was characterized using 1-D and 2-D NMR. By use of cross-polarization magic-angle spinning ¹³C NMR, the structure of the polyamide-based TR polymer was compared to that of a polyimide-based TR polymer with a nearly identical proposed structure. The NMR spectra suggest that oxazole functionality is formed for both of these TR polymers. Furthermore, gas permeation results are provided for the precursor polymers and their corresponding TR polymer. The differences in transport properties for these polymers result from differences in the isomeric nature of oxazole-aromatic linkages and morphological differences related to free volume and free volume distribution.     

中空玻璃密封胶的研究进展

介绍了几种新型中空玻璃密封胶的配制,并对其气体渗透系数、粘接性能、耐候性等进行了讨论和比较。通过比 较发现,经过改性后的中空玻璃密封胶结合了两种以上普通密封胶的优点,表现出更加优良的特性,其中硅氧烷改性 聚氨酯密封胶和含多硫化物的聚氨酯密封胶是目前中空玻璃密封胶的首选。     

Transmit-reference UWB system based on m-sequence codes

In this article,a novel transmit-reference(TR) signaling scheme is proposed for ultra-wideband(UWB) system,where by invoking m-sequence codes the reference and data pulses can be transmitted side by side to increase the data rate.This structure enables demodulation with a simple and practical autocorrelation receiver despite existence of severe inter-pulse interference(IPI).To evaluate detection performance of the new designs,closed-form expression for bit error probability(BRP) is theoretically derived and...     

Effect of cooking methods on fatty acids,conjugated isomers of linoleic acid and nutritional quality of beef intramuscular fat

The effect of boiling, microwaving and grilling on the composition and nutritional quality of beef intramuscular fat from cattle fed with two diets was investigated. Longissimus lumborum muscle from 15 Alentejano young bulls fed on concentrate or pasture was analyzed. Cooking losses and, consequently, total lipids, increased directly with the cooking time and internal temperature reached by meat (microwaving > boiling > grilling). The major changes in fatty acid composition, which implicated 16 out of 34 fatty acids, resulted in higher percentages in cooked beef of SFA and MUFA and lower proportions of PUFA, relative to raw meat, while conjugated linoleic acid (CLA) isomers revealed a great stability to thermal processes. Heating decreased the PUFA/SFA ratio of meat but did not change its n−6/n−3 index. Thermal procedures induced only slight oxidative changes in meat immediately after treatment but hardly affected the true retention values of its individual fatty acids (72–168%), including CLA isomers (81–128%).     

基于边界匹配的增强多权重差错掩盖方法研究*

提出了一种基于边界匹配的增强多权重差错掩盖算法,通过受损宏块周围时空域相邻宏块的相关信息在增强候选运动矢量集中进行运动矢量选取,采用多权重的边界匹配方法使之在物体边界处能够获得更准确的运动矢量,并专门对连续图像片丢失或整帧丢失的情况进行时域掩盖处理。基于H.26L的仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。