注入条件对SIMOX材料的影响

利用ＲＢＳ和ＴＥＭ技术分析研究了不同注入剂量、注入方式（单重注入，多重注入）对ＳＩＭＯＸ材料各层结构的影响，特别着重研究了Ｓｉ／ＳｉＯ２界面过渡区受注入条件的影响。结果表明，在注入剂量相同的情况下，多重注入不仅能改善顶层单晶、ＳｉＯ２绝缘层的质量，而且能显著减小Ｓｉ／ＳｉＯ２界面过渡区宽度。     

Low-complexity and MAI-robust wireless broadcasting system with return channel

A combination of orthogonal frequency division multiplexing (OFDM) with frequency-division multiple access (FDMA) called orthogonal frequency-division multiple access (OFDMA) is regarded as a promising solution for improving the performance of interactive wireless broadcasting systems. This paper deals with our investigations into improving the performance and reducing the complexity of a digital multimedia broadcasting (DMB) system with a return channel when OFDMA is used as an access scheme. To alleviate a multiple access interference (MAI) introduced by a symbol timing misalignment, the OFDMA-based DMB system adopts frequency diversity and cyclic suffix (CS) at the transmitter, namely FD-OFDMA DMB system with CS. When the system is fully loaded, in addition to low complexity at the transmitter, the performance of the FD-OFDMA DMB system with the CS comes close to that of a single-user FD-OFDMA system at the cost of a small loss of throughput.     

AN INVERSE PROBLEM OF WATER WAVE GENERATION IN A WAVE TANK

ＡＮＩＮＶＥＲＳＥＰＲＯＢＬＥＭＯＦＷＡＴＥＲＷＡＶＥＧＥＮＥＲＡＴＩＯＮＩＮＡＷＡＶＥＴＡＮＫＭｉａｏＧｕｏ－ｐｉｎｇ；ＹｏｕＹｕｎ－ｘｉａｎｇ；ＬｉｕＹｉｎｇ－ｚｈｏｎｇ（ＳｈａｎｇｈａｉＪａｏＴｏｎｇＵｎｉｖｅｒｓｉｔｙＳｈａｎｇｈａｉ２０００...     

宽带非相干光纤光源的分割技术

利用光学滤波器将非相干宽带光源的光谱进行分割,并将分割后的光信道调制以传输数据的波分复用技术对于 WDM系统是一种良好的解决方案。概述了国内外分割宽带非相干光源的几种方法,并介绍了宽带非相干光谱可分割光 纤光源的线宽优化的方案。     

低频天波传播预测与低电离层模式参数的测定

在理想化的均匀球面通过进一步地与具有突变边界的均匀各向同性同心球面电离层条件下的LF天波全波解的基础上，考虑由海陆之差引起的地面导电率的变化、大气和低电离层的不均匀性以及由地磁场引起的各向异性特性等因素的影响，推导出了较严格预测实际地与低电离层条件下场强与传播相延精确预测的完善公式。 给出了一些低电离层模式参数的实测结果。这些模式参数为参考高度h0、参考浓度N0与梯度参数α。由罗兰－C天波信号场强与相位的精细测量数据求得的。     

Photothermal Janus Anode with Photosynthesis‐Shielding Effect for Activating Low‐Temperature Biological Wastewater Treatment

Biological wastewater treatment (BWT), which is used to manage global wastewater, suffers from a sharp decrease in microbial activity at low temperature (<10 °C). Photothermal technology with a high energy efficiency theoretically exceeding 80% has the potential to activate low‐temperature BWT. However, photothermal BWT is threatened by the propagation of photosynthetic algae in wastewater under irradiation, and these microorganisms can suppress the functional bacteria or even kill anaerobic species by photosynthetically releasing oxygen. Herein, taking microbial fuel cells (MFCs) as a representative biological reactor, a photothermal Janus anode (PTJA) is designed, composed of a carbon black/polydimethylsiloxane photothermal nonporous layer and a graphite felt porous layer to promote low‐temperature BWT. Unlike traditional symmetrical porous anodes, the nonporous layer of the PTJA can isolate the wastewater in the porous layer from light irradiation during photothermal conversion, thus preventing photosynthetic algae from poisoning anaerobic functional microbes. Under ≈1 sun illumination, the PTJA MFC exhibits 1.6 and 24.2 times higher organic pollutant removal rate and power density generation, respectively, than MFCs using traditional anodes for low‐temperature BWT (7.0 ± 2.0 °C). This development can allow novel utilization of solar energy and is a promising resolution for low‐temperature BWT.     

Performance analysis of covert wireless communication based on beam forming with noise uncertainty

In order to establish covert wireless communication in Rayleigh fading environment with noise uncertainty,a scheme of downlink covert wireless communication based on complex Gaussian random coding and beam forming was adopted,and more importantly,the performance of covert wireless communication was analysed.Firstly,the covert probability of communication was analyzed by using the hypothesis test theory.Secondly,the optimal detection threshold of the illegal detection party was given and proved,and the closed expressions of the average covert probability,connection interruption probability and covert throughput of the system were further obtained.Finally,by jointly designing the transmission power and target covert rate,the optimal goal of the maximum covert throughput of the system was achieved,and the corresponding algorithm based on step search was given.The simulation results show that the beam forming technology could provide some gain for covert wireless communication.Compared with the ideal case in which the legitimate receiver is not affected by the noise uncertainty,the covert throughput in non-ideal case is significantly reduced and almost not affected by the basic noise level of the environment.     

Modular Layer‐by‐Layer Assembly of Polyelectrolytes,Nanoparticles, and Molecular Catalysts into Solar‐to‐Chemical Energy Conversion Devices

The design and fabrication of solar‐to‐chemical energy conversion devices are enabled through interweaving multiple components with various morphologies and unique functions using a versatile layer‐by‐layer assembly method. Cationic and anionic polyelectrolytes are used as an electrostatic adhesive to assemble the following functional materials: plasmonic Ag nanoparticles for improved light harvesting, upconversion nanoparticles for utilization of near‐infrared light, and polyoxometalate water oxidation catalysts for enhanced catalytic activity. Polyelectrolytes also have an additional function of passivating the surface recombination centers of the underlying photoelectrode. These functional components are precisely assembled on a model photoanode (e.g., Fe₂O₃ and BiVO₄) in a desired order and various combinations without degradation of their intrinsic properties. As a result, the performance of water oxidation photoanodes is synergistically enhanced. This study can enable the design and fabrication of novel solar‐to‐chemical energy conversion devices.     

Participatory or deliberative democracy? Exploring the mediation effects of perceived online deliberation and online interactive activities on social outcomes

Using the structural equation modeling method (N = 811), this study explores the structural relationships among online news consumption, political participation and social trust, with a focus on the mediating effects of online users’ deliberative perceptions and news-related online interactive activities. The analysis confirms that users’ perceptions of online deliberation exert a significant mediating effect on users’ levels of news consumption, political participation, and social trust. Users’ interactive civic messaging behaviors, on the other hand, solely enhance participatory intentions. The findings also show that the consumption of political news and the consumption of entertainment news have different effects on users’ perceptions of online deliberation, social trust, and political participation. Specifically, while political news has a direct and relatively strong influence on participation, entertainment news has a limited and indirect effect on participation. Online interactive activities are negatively associated with users’ perceived competency for online deliberation. Further implications of the study are also discussed.     

A novel iris segmentation using radial-suppression edge detection

Iris segmentation is a key step in the iris recognition system. The conventional methods of iris segmentation are based on the assumption that the inner and outer boundaries of an iris can be taken as circles. The region of the iris is segmented by detecting the circular inner and outer boundaries. However, we investigate the iris boundaries in the CASIA-IrisV3 database, and find that the actual iris boundaries are not always circular. In order to solve this problem, a new approach for iris segmentation based on radial-suppression edge detection is proposed in this paper. In the radial-suppression edge detection, a non-separable wavelet transform is used to extract the wavelet transform modulus of the iris image. Then, a new method of radial non-maxima suppression is proposed to retain the annular edges and simultaneously remove the radial edges. Next, a thresholding operation is utilized to remove the isolated edges and produce the final binary edge map. Based on the binary edge map, a self-adaptive method of iris boundary detection is proposed to produce final iris boundaries. Experimental results demonstrate that the proposed iris segmentation is desirable.