New results in 2D optimal control theory

The infinite horizon optimal control problem is solved for 2D systems described by the Fornasini-Marchesini model. An ₂-approach permits us to reduce the optimal control problem to a norm minimization one in Hilbert spaces. Both necessary and sufficient conditions for solvability and the structure of the solution are established. Moreover, a comparison with known results is presented, and the singularities of the 2D Riccati equation are examined in order to characterize suboptimal control laws that apply whenever the solvability conditions are not satisfied.     

热分解法制备钛酸铅镧薄膜及其电性能研究

本文研究了用金属有机物热发解法制备ＰＬＴ８薄膜的工艺过程和基片对薄膜结构的影响，并且给出了铁电性能的测量结果。     

Photocurrent effect on the zero-Bias dynamic resistance of HgCdTe photodiode

A new physical model is presented for the illumination-dependence of the zero-bias resistance-area product (R₀A) of HgCdTe photodiode. The model is based on three independent mechanisms. They are the depletion region volume change with the applied bias, the diffusion distance change with the moving depletion region edge, and the minority carrier accumulation in the depletion region which affects the minority carrier diffusion. Analytic equations are derived for the photodiode current-voltage characteristics and R₀A products. The results of the model have been compared with experimental data obtained from several Hg_0.7Cd_0.3Te diodes with an identical diode structure having different absorbing amount of light. The model showed good agreement with the experimental data.     

基于SL0的高分辨率Radon变换及数据重建

L₀范数是度量数据稀疏度的最优方法,但它具有的非凸性造成求解困难。本文将光滑L₀范数（Smoothed L₀ Norm,SL₀）稀疏约束引入Radon变换中,降低了其求解难度,并进一步提高了Radon变换的分辨率。即通过构建平滑的连续函数逼近L₀范数,以此作为抛物线Radon变换的目标函数,采用最速下降法和梯度投影原理获得最优解。理论模型和实际地震数据重建试验结果表明,该方法进一步提高了Radon变换分辨率,较好地恢复了缺失地震数据的连续性和AVO特性。     

π‐Conjugated Molecules Crosslinked Graphene‐Based Ultrathin Films and Their Tunable Performances in Organic Nanoelectronics

Graphene‐based ultrathin films with tunable performances, controlled thickness, and high stability are crucial for their uses. The currently existing protocols, however, could hardly simultaneously meet these requirements. Using amino‐substituted π‐conjugated compounds, including 1,4‐diaminobenzene (DABNH2), benzidine (BZDNH2), and 5,10,15,20‐tetrakis (4‐aminophenyl)‐21H,23H‐porphine (TPPNH2), as cross‐linkages, a new protocol through which graphene oxide (GO) nanosheets can be anchored on solid supports with a high stability and controlled thickness via a layer‐by‐layer method is presented. A thermal annealing leads to the reduction of the films, and the qualities of the samples can be inherited by the as‐produced reduced GO films (RGO). When RGO films are integrated as source/drain electrodes in OFETs, tunable performances can be realized. The devices based on the BZDNH2‐crosslinked RGO electrodes exhibit similar electrical behaviors as those based on the non‐π‐conjugated compound crosslinked electrodes, while improved performances can be gained when those crosslinked by DABNH2 are used. The performances can be further improved when RGO films crosslinked by TPPNH2 are employed. This work likely paves a new avenue for graphene‐based films of tunable performances, controlled thickness, and high stability.     

Harnessing “Click”‐Type Chemistry for the Preparation of Novel Electronic Materials

Sequence‐independent or “click”‐type chemistry is applied for the preparation of novel π‐conjugated oligomers. A variety of bi‐functional monomers for Wittig–Horner olefination are developed and applied in a sequential protection–deprotection process for the preparation of structurally similar π‐conjugated oligomers. Selected oligomers are incorporated as the organic semiconductors in light‐emitting diodes and a field‐effect transistor, demonstrating the potential of the approach.     

天地基综合观测的东日本大地震电离层异常分析

介绍了地震电离层前兆的主要特性,并给出了掩星电离层电子密度峰值位置的标高估计技术。利用天地基电离层观测数据,综合分析了2011年3月11日日本9.0级大地震发生前的电离层异常变化,发现地震前3天内电离层f0F2异常扰动、相对垂直总电子含量（VTEC）扰动以及电子密度峰值处标高（Hs）增加等多种异常现象。分析了地磁活动和太阳活动等因素后,认为其可能与地震有一定关联,表明电离层异常变化对于地震短期预报具有重要参考意义。     

直缝焊管焊缝质量电磁超声检测方法研究

为实现直缝焊管焊缝内缺陷检测,采用周向电磁超声SH0导波检测技术,研究了基于磁致伸缩效应激励周向SH0模态导波,确定了周向SH0导波激励频率,设计了一款一发双收差分接收的直缝焊管焊缝缺陷检测探头。结果表明:该系统能够激发单一模态周向SH0导波,实际波速与模型分析结果吻合;针对直径116 mm、壁厚3.5 mm的激光直缝焊管焊缝的Φ0.6 mm盲孔和Φ1.0 mm通孔,通过差分探头的信号处理,能够实现焊缝处Φ1.0 mm通孔和Φ0.6 mm盲孔缺陷的检测。     

微波促进稀土固体超强酸S2O2-8/Sb2O3/La3+催化合成乙酸苄酯

采用金属醇盐水解法制备了稀土固体超强酸S2 O2-8/Sb2O3/La3 催化剂,并用Hammett,IR,DTA/TGA,XRD等手段对催化剂进行了表征.以稀土固体超强酸S2O2-8/Sb2O3/La3 为催化剂、乙酸和苯甲醇为原料,在微波辐射下合成了乙酸苄酯.考察了催化剂制备条件及合成条件对酯化率的影响,催化剂最佳制备条件:用1.5 mol/L的(NH4)2S2O8和2.71%La(NO3)3混合溶液浸渍前体氧化物Sb2O3,经110℃烘干,于500℃焙烧3 h.最佳合成条件:n(苄醇):n(乙酸)=2:1,催化剂用量0.6 g,辐射时间25 min,微波功率528W,酯化率93.8%.用IR、1H NMR等手段对产物进行了确证.     

Investigation of novel anthracene‐bridged carbazoles as sensitizers and Co‐sensitizers for dye‐sensitized solar cells

Novel anthracene‐bridged carbazole organic dyes (designated ML4 and ML5) were synthesized using the Suzuki coupling reaction. These dyes were designed to be donor‐π‐conjugation‐acceptor sensitizers for dye‐sensitized solar cells, where the carbazole moiety acts as the donor, the anthracene moiety provides the π‐conjugation, and the cyano acrylic acid acts as the acceptor. Solar cells were fabricated with ML4 and ML5 alone with low power conversion efficiencies, but they were also used as co‐sensitizers with N719, improving the efficiency of the dye‐sensitized solar cells produced by ~3% and ~10%, respectively. Copyright © 2015 John Wiley & Sons, Ltd.