基于非饱和光诱导延迟荧光的光合能力检测

针对饱和光诱导延迟荧光(DF)进行植物光合能力快速检测方法中存在的耗电量大、可持续工作时间短的问题,以水稻叶片为样品,实验分析了不同非饱和光与饱和光诱导下DF衰减动力学曲线及强度间的关系,用自制的便携式叶片在位DF检测系统测定样品DF强度,并与广泛使用的LI-6400光合速率测定仪测量的样品光合能力进行对比测试实验。实验结果表明,非饱和光与饱和光诱导DF的衰减动力学曲线具有相同的衰减趋势;曲线下面积有很好的线性相关性;非饱和DF强度与光合能力具有良好的线性相关性。因此,非饱和光诱导DF光强度可以作为表征植物光合能力的手段。     

植物光合能力检测中延迟荧光诱导参数优化

为优化延迟荧光诱导参数,以大豆（Ke FengNo．1）叶片为样品,分析了影响延迟荧光强度的激发光强、激发时间和温度优化过程,并在优化条件下对样品进行了延迟荧光强度与相应净光合速率的对比测量。实验结果表明,优化条件下,两者具有极好的线性相关性（R1=0．989）。     

植物光诱导延迟荧光的紫外辐射环境胁迫监测

以科丰1号大豆品种为测试模式,利用自制的便携式延迟荧光(DF)检测系统,研究了紫外(UV-B)辐射对其DF特征的影响.结果发现,绿色植物叶片光诱导DF强度的变化可以准确地反应叶绿素含量以及光合作用能力的变化.因此,DF强度可以用来表征UV-B辐射对植物的伤害程度.     

发光二极管辐照光合能力快速检测系统

提出了一种以AT89c55单片机为核心实现对植物光诱导延迟荧光(DF)采集和处理的发光二极管(LED)辐照光合能力快速检测系统。该系统利用DF来表征植物的光合能力,采用DF衰减动力学曲线下面积积分作为表征方法。该系统基于弱光探测技术,采用通道光电倍增管直流模块(CPDM)来接收DF,具有很高的精度和信噪比,自带LED激发光源及温度控制,并采用小型密封暗室设计和电池供电,便于携带,可以进行现场活体测量。实验结果表明,该系统的测量精度可以达到±0.3μmol CO2m-2·s-1,具有低成本、高精度和方便实用等优点,是一种具有广阔应用前景的实用化光合能力测量仪器。     

小麦叶片、叶肉细胞、叶绿体的形态、结构与光合速率的关系

本文在前人工作基础上,以二、四、六倍体不同小麦种为材料,从叶片、叶肉细胞和叶绿体三个不同层次上,结合小麦的进化过程,研究其形态、解剖和超微结构与光合速率的关系,为阐明小麦光合生产力进化趋势提供依据。一、叶片形态、结构和光合速率的关系。小麦进化过程中叶面积扩大,光合速率下降(二倍体及野生种叶面积小,光合速率高,多倍体及载培种叶面积大,光合速率低,伴随着叶面积扩大同时发生了一系列叶片形态和细胞学特征方面的变化,它们从不同方向上(正或负)影响着光合作用,其综合结果使光合速率下降,其中叶脉间距与气孔频率的作用最为明显。Austin,Dunstone和Sasa hara等也有类似指导。二、叶肉细胞形态、结构与光合速率的关系。     

被动矩阵垂直配向液晶显示器光程差的表征与测量

在不加电场的情况下,被动矩阵垂直配向液晶显示器(PMVA-LCD)对于垂直入射光不产生相位延迟,故无法表征及测量其光程差.通过对PMVA-LCD透过率与电压关系的理论推导及模拟得出,在电压增大到一定值后,其透过率随电压增大而保持稳定,即此时光程差保持稳定,这一数值可用来表征PMVA-LCD的光程差.对实际样品进行测试,得到的结果与理论分析结果较为接近,之间的误差主要由白光的色散现象引起.根据此方法,可以方便地匹配液晶层的△nd值与C-plate补偿片的补偿值R,使得PMVA-LCD达到更好的显示效果.     

Rb(5PJ)与Ne、N2碰撞诱导激发能量转移

在气体样品池条件下,研究了Rb(5PJ) (Ne、N2)碰撞能量转移过程.用调频半导体激光器激发Rb原子至Rb(5P3/2)态,在不同的Ne或N2气压下,测量了直接5P3/2→5S1/2荧光和转移5P1/2→5S1/2荧光.对于5PJ与Ne的碰撞,电子态能量仅能转移为Ne原子的平动能.在与N2的碰撞中,向分子振转态的转移是重要的.利用速率方程分析,可以得到碰撞转移速率系数,对于Ne,5P3/2→5S1/2转移速率系数为1.53×10-12cm3s-1.对于N2,测量5PJ Ne和5PJ N2二种情况下荧光的相对强度比,利用最小二乘法确定5P3/2→5S1/2转移速率系数为1.05×10-10cm3s-1,5PJ态猝灭速率系数为1.12×10-10cm3s-1.与其他实验结果进行了比较.     

利用光诱导延迟荧光的植物生长调节剂调控效应监测

叶绿体的发育与功能以及叶片的光合作用代谢会受到植物生长调节剂(PGRs,plant growth regulators)的重要调节.光诱导延迟荧光(DF,delayed fluorescence)被认为是叶绿体光系统Ⅱ(PSII)可逆光化学反应的结果,是PSⅡ光化学效率的灵敏探针.本文以蚕豆为实验材料,利用自行研制的便携式延迟荧光生物传感器,研究了八种不同作用模式的PGRs对蚕豆幼苗DF特征的影响.结果发现,绿色植物叶片光诱导DF强度的变化可以准确的反应PGRs对蚕豆植株生长和光合作用代谢的调控效应.因此,DF技术有望成为农业生产中PGRs对作物生长发育调控效应早期、实时、在位监测的一个便捷、无损的新方法.     

PMD补偿反馈控制信息DOP与DGD的数学模型

与电功率反馈控制信息相比,偏振度(DOP)作为偏振模色散(PMD)动态补偿技术中的反馈控制信息在码率透明等方面有其优势.本文以准单色光理论和2×2相干矩阵为基础,推导了DOP与差分群延迟(DGD)之间的一般数学关系,推导中考虑了光脉冲波形函数、脉冲宽度、光在两个偏振主态上分光比等因素对这一关系的影响;给出了表示两偏振主态(PSP)方向上光脉冲交叠程度的相干函数;计算了当脉冲波形函数为高斯型时DOP的表示式,给出了当分光比为0.5和不同高斯脉冲宽度下光偏振度随差分群延迟变化的关系曲线.将理论计算结果与用10Gb/s的伪随机序列在归零码(RZ)下的实验测量数据进行了比较,表明在一定的DGD范围内理论计算与实验结果一致.     

光纤束传感器测量叶片同步振动幅值的研究

基于叶尖定时测振原理,设计了用于叶尖定时的光纤束式传感器,并对速矢端迹法叶片同步共振的分析方法做了理论推导以及对测量过程做计算机仿真.将该方案在某型号航空设备上进行模拟实验,分析结果与理论模型相符,所测幅值与应变片测量的结果基本一致.     

连续波DF化学激光器无稀释剂实验及其分析

为了增强对燃烧驱动连续波DF化学激光器的理解,特别是为了提高对燃烧室中F原子产生环境和光腔内激射环境的认识,进行了一系列DF激光器无稀释剂条件下的出光实验。结果显示,无主稀释剂条件下,DF激光器同样可以达到较高的功率水平和质量流比功率,无副稀释剂条件下,输出功率和比功率将损失一半左右。根据实验数据,定性地分析了主、副稀释剂对激光器运转的影响。DF化学激光器能够在无稀释剂条件下出光,为简化激光器设计提供了依据。     

基于航迹参数估计的雷达测向相对系统误差修正方法

采用单雷达加权直线航迹线参数估计模型,计算主、副站雷达观测到的目标航向以及副站相对于主站的测向相对系统误差,并以此结果修正副站其他测量中的方位值。试验结果表明,该方法航迹修正效果理想,对于提高多雷达目标状态估计的一致性和准确性具有重要意义。     

Outage Probability of Regenerative Protocols for Two-Source Two-Destination Networks

In this paper, the analytical expressions for the outage probability of different decode-and-forward (DF) relaying strategies for two-source two-destination networks are evaluated allowing an investigation of their effectiveness in energy saving to be determined. Each source node transmits data to an interested destination node with the help of the remaining source node in a cooperative DF manner. Specifically, we consider four DF protocols, including repetition DF (RDF), parallel DF (PDF), network coding-based RDF (NC-RDF), and dirty paper coding-like network coding-based PDF (DPC-NC-PDF). The closed-form expression of the outage probability for each protocol is derived at high signal-to-noise ratio. The results show that the DPC-NC-PDF protocol achieves the best performance while the NC-RDF protocol is better than both the RDF and PDF protocols with proper linear NC coefficients. All the DF protocols are shown to achieve diversity order one and the highest multiplexing gain is achieved with the NC-RDF and DPC-NC-PDF protocols. Finally, simulation results are presented to verify the analytical findings and show the system throughput comparison of various DF protocols.     

Characterizing the orthogonality factor in WCDMA downlinks

The loss of orthogonality between the spreading codes in a wideband code-division multiple-access downlink is modeled in analysis and simulations by means of the orthogonality factor (OF). The OF, which is an important parameter limiting downlink capacity, increases with the multipath dispersion in the channel. We utilize this relationship between the OF and the channel dispersion to show a novel, simple, and accurate way to determine the time-averaged OF directly from the channel delay profile. To this end, we define the diversity factor (DF) of a channel profile, derive the expression for it, and show that the DF and the OF are related by a simple mathematical relationship. We then verify our approach over an entire ensemble of channel profiles generated by the general COST259 macrocellular channel model.     

On the Diversity Order of a General Cooperative Relaying Communication System

Cooperative communication technology exploiting distributed spatial diversity is a promising solution for the future high data-rate cellular and ad-hoc wireless communications. To characterize the performance of a cooperative network, the cooperative diversity is commonly used. In this paper, we revisit the concept of diversity and look into the essence of cooperative diversity. We analyze the diversity performance of a general cooperative relaying system with multiple branches. Moreover, each branch consists of one or more hops. Unlike in other analyses, the assumptions that each node being only equipped with a single antenna and that all channel characteristics belonging to the same family are NOT required in our study. Using the decode-and-forward (DF) relaying protocol as an illustration, we provide analytical results on the diversity gain and the coding gain. The results also encompass most of the existing results as special cases. We further show the relationship between the diversity order of a branch and those of the constituent links; and the relationship between the diversity order of the network and those of the constituent branches. In particular, we show that for the uncoded DF protocol, the full diversity order can be achieved by using simple hard-decision detection at the destination. The requirement is to set appropriate signal-to-noise-ratio (SNR) thresholds for the multi-hop branches. To improve the bandwidth efficiency, we also randomly select one branch, among those branches satisfying the SNR-threshold requirement, for the transmission. We show that such a scheme accomplishes the full diversity order and produces a good error performance.     

Minimum Mean-Squared Error Iterative Successive Parallel Arbitrated Decision Feedback Detectors for DS-CDMA Systems

In this paper we propose minimum mean squared error (MMSE) iterative successive parallel arbitrated decision feedback (DF) receivers for direct sequence code division multiple access (DS-CDMA) systems. We describe the MMSE design criterion for DF multiuser detectors along with successive, parallel and iterative interference cancellation structures. A novel efficient DF structure that employs successive cancellation with parallel arbitrated branches and a near-optimal low complexity user ordering algorithm are presented. The proposed DF receiver structure and the ordering algorithm are then combined with iterative cascaded DF stages for mitigating the deleterious effects of error propagation for convolutionally encoded systems with both Viterbi and turbo decoding as well as for uncoded schemes. We mathematically study the relations between the MMSE achieved by the analyzed DF structures, including the novel scheme, with imperfect and perfect feedback. Simulation results for an uplink scenario assess the new iterative DF detectors against linear receivers and evaluate the effects of error propagation of the new cancellation methods against existing ones.     

Regenerative Cooperative Diversity with Path Selection and Equal Power Consumption in Wireless Networks

Recently developed cooperative protocol with distributed path selection provides a simple and practical means of achieving full cooperative diversity in wireless networks. While the best path selection method can significantly improve bit error rate (BER) performance, it may cause unequal power consumption among relay nodes, which may reduce the lifetime of energy-constrained networks. A path selection method under the equal power constraint has been developed for the amplifyand- forward (AF) protocol, but there is no such method for the decode-and-forward (DF) protocol. In this paper, we develop a distributed path selection method with an equal power constraint for the DF protocol. We also analyze the BER performance of our path-selection method. Numerical results demonstrate that the proposed method can guarantee equal power consumption, while achieving full diversity as the best path selection method and providing significant performance gain relative to noncooperative communication.     

Mixed AF and DF cooperative relay systems and their performance bounds analyses

This paper analyzes the performance bounds of a wireless relay system consisting of several relay stations working on both amplifier‐and‐forward (AF) and decode‐and‐forward (DF) protocols. We want to study the outage probability behavior of the proposed mixed AF and DF relay systems under independent Nakagami‐m fading channels. In particular, we will derive the lower and upper bounds of outage probability of the mixed AF and DF relay systems based on maximal ratio combining diversity reception. The results give optimal configuration of AF and DF relays under a specific channel condition, thus helping us to design an optimized mixed AF and DF relay system in a generic fading environment. The trade‐off between complexity and performance is discussed in this paper. In addition, we will use computer simulations to verify the effectiveness of the proposed mixed AF and DF relay configurations. Finally, the power allocation issues for such a mixed AF and DF relay system will also be discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

An achievable rate region of cooperative multiple-access channels with hybrid CF and DF cooperation

In this letter, we derive an achievable rate region of a two-user cooperative multiple-access (CMA) channel where one user performs decode-and-forward (DF) cooperation and the other user performs Wyner-Ziv-type compress-and-forward (CF) cooperation. The proposed rate region is achieved using a communication scheme that applies block Markov coding at each user and backward decoding at destination. Numerical results show that for some channel scenarios, the proposed hybrid CF and DF cooperation scheme enlarges the rate region achieved by the pure DF-based cooperation scheme.