A new coding scheme of QC-LDPC codes for optical transmission systems

Based on Galois Field (GF(q)) multiplicative group, a new coding scheme for Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes is proposed, and the new coding scheme has some advantages such as the simpler construction, the easier implementation encoding, the lower complexity of the encoding and decoding, the more flexible adjustment of the code length as well as the code rate and so forth. Under the condition of considering the characteristics of optical transmission systems, an irregular QC-LDPC (3843,3603) code to be suitable for optical transmission systems is constructed by applying the proposed new coding scheme. The simulation result shows that the net coding gain (NCG) of the irregular QC-LDPC (3843,3603) code is respectively improved 2.14 dB, 1.19 dB, 0.24 dB and 0.14 dB more than those of the classic RS (255,239) code in ITU-T G.975, the LDPC (32640,30592) code in ITU-T G.975.1, the regular SCG-LDPC (3969,3720) code constructed by the Systematically Constructed Gallager (SCG) coding scheme and the regular QC-LDPC (4221,3956) code at the bit error rate (BER) of 10-8. Furthermore, all the five codes have the same code rate of 93.7%. Therefore, the irregular QC-LDPC (3843,3603) code constructed by the proposed new coding scheme has the more excellent error-correction performance and can be better suitable for optical transmission systems.     

基于错误矩阵方程的解决城市交通拥堵决策研究

针对解决城市交通拥堵决策问题,首先给出了错误优化矩阵的概念,在此基础上引出错误矩阵方程的概念,利用消错理论中的错误优化矩阵方程,从错误优化的角度来研究并解决城市交通拥堵的决策方法.相应结合实际状况给出当前状态矩阵,从而进行下一步的求解,步步推理获得了决策人满意的方案集,为决策者提供最优建议.     

New lower bounds on 2-spontaneous emission error designs

The combinatorial object named $t$-spontaneous emission error design ($t$-SEED) was proposed by Beth et al. in 2003 in order to correct errors caused by quantum jumps. The newly rising category of $t$-SEEDs has been studied extensively in recent years. Especially, the maximal possible dimensions for 2-SEEDs with block size 3 were determined completely; lower bounds on 2-SEEDs were established by applying affine groups. In this paper we utilize the action of twisted affine groups on finite fields and obtain new lower bounds on the dimensions of 2-$(q^2,k;m)$ SEEDs, some of which outperform the known ones.     

Optimal recovery of integral operators and its applications

In this paper we present the solution to a problem of recovering a rather arbitrary integral operator based on incomplete information with error. We apply the main result to obtain optimal methods of recovery and compute the optimal error for the solutions to certain integral equations as well as boundary and initial value problems for various PDE’s.     

误差合成空间固定系数模型的多阶段广义最小二乘估计

本文对时变系数的空间面板数据模型进行了研究,所研究的模型利用扰动项中的空间个体成分将不同时期的方程联系起来,同时,自变量系数和空间自回归系数是时变的,但不会随着观测个体的变动而变动。本文利用基于可行的广义最小二乘估计的多阶段方法对模型参数进行了估计,研究了估计量的大样本性质,并利用Monte Carlo方法模拟了其小样本性质。模拟结果表明,估计量的渐近性质随着样本容量的增加而改善。对中国省级地区间财税策略互动行为的实证案例也体现了本文理论模型的应用价值。     

采用一维物理光学法的天线罩瞄准误差补偿

针对雷达天线罩瞄准误差的补偿问题，提出了一种适用于各向同性的天线罩瞄准误差修正方法。构建了基于一维物理光学法的天线罩瞄准误差的数学模型，推导了雷达导引头测量目标角度和角速度的误差修正公式。试验结果表明，该方法有效降低了天线罩瞄准误差对目标角速度性能的影响。     

On reconstruction of objects from measurements of the diffracted field (*)

The aim of this paper is the shape restoration of a plane object from measurements of its diffracted field at a discrete and finite set of points. The plane sampling lattice is supposed: i) rectangular; ii)periodic.

The problem is approached as an interpolation one. A numerical algorithm for practical reconstructions is presented. A-priori limitations on the perimeter of the object and conditions on the samples lead to a-priori bounds able to estimate the precision of the reconstruction.     

Graceful Degradation FEC Layer for Multimedia Broadcast/Multicast Service in LTE Mobile Systems

This paper proposes an additional forward error correction (FEC) layer to compensate for the defectiveness inherent in the conventional FEC layer in the Long Term Evolution specifications. The proposed additional layer is called a graceful degradation (GD)‐FEC layer and maintains desirable service quality even under burst data loss conditions of a few seconds. This paper also proposes a non‐delayed decoding (NDD)‐GD‐FEC layer that is inherent in the decoding process. Computer simulations and device‐based tests show a better loss recovery performance with a negligible increase in CPU utilization and occupied memory size.     

水胁迫下典型盐生植被梭梭光谱特征分析

荒漠地区由于气候干燥，降水稀少，水分常成为制约植被生长的因素之一，水分胁迫对植物长势和产量的影响比任何其他胁迫都要大。随着高光谱技术的发展，国内外已有众多学者利用高光谱数据研究植被遭受胁迫作用，然而这些研究对象多集中于甜菜、棉花、玉米、水稻等作物，针对干旱区盐生植被遭受胁迫作用的研究较少。梭梭作为荒漠、半荒漠地区的典型盐生植被之一，具有极高的经济和生态效益。选择梭梭作为研究对象，培育一年生梭梭，并设置三个水分梯度，形成受不同水分量胁迫的梭梭。使用原始光谱、红边位置参数，结合植被指数及二维相关光谱研究其叶片光谱特征，为干旱区利用高光谱遥感监测盐生植被提供借鉴。结果表明：(1)分析梭梭叶片反射光谱曲线发现，在可见光至中红外各波段范围内，受不同水分量胁迫作用的梭梭叶片光谱反射率有显著差异。在可见光(350～610 nm)波段，各水分处理的梭梭叶片反射率依次为100 mL>500 mL>200 mL，这是由于100和200 mL水分促进梭梭内部叶绿素合成，使该波段反射率降低，而过多的水分(500 mL)对梭梭内部的叶绿素合成没有更大的促进作用。在红光区(611～738 nm)，随着水分量的增多，受不同水分量胁迫的梭梭叶片光谱反射率依次减小。在738～1 181和1 228～1 296 nm波段，受不同水分量胁迫作用的梭梭叶片光谱反射率为：200 mL>100 mL>500 mL；在1 182～1 227 nm波段，受不同水分量胁迫作用的梭梭叶片光谱反射率为：100 mL>200 mL>500 mL。这是由于植被细胞结构对近红外区域的反射率影响较大，因而受不同水分胁迫作用的梭梭叶片光谱反射率有显著差异。在1 300～1 365和1 392～1 800 nm波段，受各水分胁迫作用的梭梭叶片反射率为：100 mL>200 mL>500 mL。这表明在500 mL水分胁迫量范围内，水分越多，叶子的细胞液、细胞膜对水分的吸收能力越强，使得反射率下降。通过对原始光谱求取一阶导数并提取红边位置参数发现，各水分处理下的梭梭叶片一阶微分光谱曲线中红边位置未发生移动。这是由于梭梭在长期的干旱环境影响下，形成了特殊的适应机制，水分对其红边位置影响不敏感。(2)选取若干植被指数分析各水分处理下的梭梭光谱指数变化。当水分胁迫量由100 mL增至200 mL时，WI/NDWI，MSI和NDII指数值变化显著，可用于研究水分胁迫下梭梭的光谱特征。(3)使用二维相关光谱技术分析受各水分胁迫作用的梭梭光谱特征，得出在100 mL水分胁迫下，在536，643，1 219和1 653 nm波段处，吸收峰对水分的微扰敏感；在200 mL水分胁迫下，在846和1 083 nm波段处，吸收峰对水分的微扰敏感；在500 mL水分胁迫下，在835和1 067 nm波段处，吸收峰对水分的微扰敏感。总之，在近红外波段，与100 mL水分量相比，梭梭受200和500 mL水分量胁迫时，吸收峰对水分的微扰敏感度上升。由100 mL水分胁迫下梭梭的二维同步相关谱图可知，1 044和1 665 nm，1 072和903 nm，903和1 264 nm，1 230和1 061 nm波段处形成正交叉峰，表明这些波段处光谱强度随水分的干扰同时变化。