Gradient Fusion Method for Night Video Enhancement

To resolve video enhancement problems, a novel method of gradient domain fusion wherein gradient domain frames of the background in daytime video are fused with nighttime video frames is proposed. To verify the superiority of the proposed method, it is compared to conventional techniques. The implemented output of our method is shown to offer enhanced visual quality.     

Propagation characteristics of a circular waveguide coated inside with a metamaterial

The problem of guided wave propagation of a circular waveguide that is coated on the inside with a metamaterial coating is studied by a boundary value approach and the propagation features cylindrical waveguide are studied by solving the resultant characteristic equation numerically. The results are compared to those with an inside dielectric coating. The variation of the normalized phase constant is studied as a function of the parameters of the coating including the permittivity and permeability, the coating thickness expressed as a ratio of b/a, and frequency. The behavior of the cylindrical waveguide is shown to be significantly different from that with a dielectric coating.     

WiFi外辐射源雷达参考信号重构及其对探测性能影响研究

利用WiFi (Wireless Fidelity)信号作为外辐射源进行探测可获得较好的性能,然而WiFi信号本身及其应用环境的复杂性又决定了其参考信号获取的难度。该文分析了利用WiFi信号进行探测的特点,探讨了参考信号获取的不同方式,针对典型WiFi信号结构,提出了与WiFi无源探测相适应的参考信号重构方法,并结合接收信号的信噪比分析了参考信号重构质量对探测性能的影响。研究表明,参考信道所接收信号的信噪比越高,其解调误比特率越低,重构后的参考信号对于杂波抑制性能越好,其模糊函数噪声基底也越低,越有利于目标探测。同时,针对接收信号中的非监测信号成分所产生的虚假目标重影,提出了基于重构的参考信号修正方法进行消除。仿真分析表明了以上处理方法对参考信号获取的有效性。      

A next-generation optical regional access network

We describe an optical regional access network which combines electronic IP routing with intelligent networking functionality of the optical WDM layer. The optical WDM layer provides such networking functions as network logical topology reconfiguration, optical flow switching to offload traffic and bypass IP routers, wavelength routing of signals, protection switching and restoration in the optical domain, and flexible network service provisioning by reconfigurable wavelength connectivity. We discuss key enabling technologies for the WDM layer and describe their limitations. The symbiosis of electronic and optical WDM networking functions also allows support for heterogeneous format traffic and will enable efficient gigabit-per-second user access in next-generation Internet networks     

Miniaturized Fiber-Optic Fabry-Perot Interferometer for Highly Sensitive Refractive Index Measurement

This paper presents a novel miniaturized fiber-optic Fabry-Peort interferometer （FPI） for highly sensitive refractive index measurement. This device was tested for the refractive indices of various liquids including acetone and ethanol at room temperature. The sensitivity for measurement of refractive index change of ethanol is 1138 nm/RIU at the wavelength of 1550 nm. In addition, the sensor fabrication is simple including only cleaving, splicing, and etching. The signal is stable with high visibility. Therefore, it provides a valuable tool in biological and chemical applications.     

Opportunities and Challenges of Peer-to-Peer Internet Video Broadcast

There have been tremendous efforts and many technical innovations in supporting real-time video streaming in the past two decades, but cost-effective large-scale video broadcast has remained an elusive goal. Internet protocol (IP) multicast represented an earlier attempt to tackle this problem but failed largely due to concerns regarding scalability, deployment, and support for higher level functionality. Recently, peer-to-peer based broadcast has emerged as a promising technique, which has been shown to be cost effective and easy to deploy. This new paradigm brings a number of unique advantages such as scalability, resilience, and effectiveness in coping with dynamics and heterogeneity. While peer-to-peer applications such as file download and voice-over-IP have gained tremendous popularity, video broadcast is still in its early stages, and its full potential remains to be seen. This paper reviews the state-of-the-art of peer-to-peer Internet video broadcast technologies. We describe the basic taxonomy of peer-to-peer broadcast and summarize the major issues associated with the design of broadcast overlays. We closely examine two approaches - tree-based and data-driven - and discuss their fundamental tradeoff and potential for large-scale deployment. Lastly, we outline the key challenges and open problems and highlight possible avenues for future directions.     

自适应光纤光源准直器的结构设计

设计了一种可以快速高精度调节光纤准直激光束发射角度的自适应光纤光源准直器.该器件利用双压电驱动器控制光纤端面的位置,通过准直透镜实现出射激光束的准直.建立了自适应光纤光源准直器的物理模型,通过理论分析得出了光纤端面的偏移与器件结构参数的关系.研制了一个器件,并对其光纤端面偏移量、谐振频率等进行了测试.实验结果表明,理论...     

Changes in carbohydrates and the activity of α-galactosidase,pentosanase and lipase during germination of groundnuts (Arachis hypogea)

The quantitative changes in carbohydrates of two varieties (i.e., red netal and HG-4) of groundnuts during germination have been investigated. On germination, raffinose, stachyose and verbascose decreased gradually up to 48 h and almost disappeared completely in later stages of germination (140 h). Glucose and fructose levels increased 4–6 fold; while sucrose content increased considerably throughout germination in both the varieties of groundnuts. The starch content increased about four fold during germination in both the varieties. The pentosan content was almost constant up to 36 h but decreased in later stages of germination. The oil content decreased significantly from 52 to 8.0%. The fairly high initial α-galactosidase and lipase activity in resting seeds, increased considerably during germination in both the varieties studied. On the other hand the pentosanase activity was not detected up to 36 h of germination but it appears to increase abruptly afterwards.     

A novel tunable gain equalizer based on a long-period fiber grating written by high-frequency CO/sub 2/ laser pulses

A novel tunable gain equalizer based on the long-period fiber grating (LPFG) induced by high-frequency CO/sub 2/ laser pulses is demonstrated, for the first time, to our knowledge. Both the resonant wavelength and the resonant peak amplitude of the novel LPFG have a good linearity with temperature and transverse load, respectively. The wavelength and the peak amplitude of the gain equalizer can be tuned by the means of adjusting temperature and transverse load independently, showing that this tunable equalizer is a practical approach to realizing dynamic gain equalization in erbium-doped fiber amplifier systems.     

Cross-coupled dual-spiral high-temperature superconducting filter

A microstrip bandpass filter implemented with dual-spiral resonators is described in this letter. The dual-spiral resonators make the filter compact and allow implementation of positive and negative inter-resonator couplings. Implementation of the positive and negative couplings is used to introduce a pair of finite frequency transmission-zeros in the filter response. The two zeros are designed to be close to the passband, thus improving the selectivity of the filter. As an example, a four-stage cross-coupled dual-spiral filter is designed and fabricated using superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films deposited on LaAlO/sub 3/ substrate.