基于差分传递函数法的大口径平面镜检测

为了实现大口径平面镜的原位检测,本文基于差分传递函数结合瑞奇康芒检测架构,利用全息检测方法结合瑞奇康芒法,通过光瞳的遮拦编码实现大口径平面镜的面形检测。首先,对基于差分传递函数法的大口径平面镜检测基本原理进行了推导,并将现有的大口径波前与重建波前进行对比。最后,利用变形镜搭建了检测光路。本文方法所得到面形与输入面形相关性不低于70%。本文的研究成果对宇宙“首光”探测以及“一黑两暗三起源”等宇宙学基础命题的研究均有十分重要的意义。

Rough Outlier Detection Based Security Risk Analysis Methodology

Security is a nonfunctional information system attribute that plays a crucial role in wide sensor network application domains. Security risk can be quantified as the combination of the probability that a sensor network system may fail and the evaluation of the severity of the damage caused by the failure. In this paper, we devise a methodology of Rough Outlier Detection (ROD) for the detection of security-based risk factor, which originates from violations of attack requirements (namely, attack risks). The methodology elaborates dimension reduction method to analyze the attack risk probability from high dimensional and nonlinear data set, and combines it with rough redundancy reduction and the distance measurement of kernel function which is obtained using the ROD. In this way, it is possible to determine the risky scenarios, and the analysis feedback can be used to improve the sensor network system design. We illustrate the methodology in the DARPA case set study using step-by-step approach and then prove that the method is effective in lowering the rate of false alarm.

Multi-Owner Keyword Search over Shared Data without Secure Channels in the Cloud

Searchable encryption allows cloud users to outsource the massive encrypted data to the remote cloud and to search over the data without revealing the sensitive information. Many schemes have been proposed to support the keyword search in a public cloud. However,they have some potential limitations. First,most of the existing schemes only consider the scenario with the single data owner. Second,they need secure channels to guarantee the secure transmission of secret keys from the data owner to data users. Third,in some schemes,the data owner should be online to help data users when data users intend to perform the search,which is inconvenient.In this paper,we propose a novel searchable scheme which supports the multi-owner keyword search without secure channels. More than that,our scheme is a non-interactive solution,in which all the users only need to communicate with the cloud server. Furthermore,the analysis proves that our scheme can guarantee the security even without secure channels. Unlike most existing public key encryption based searchable schemes,we evaluate the performance of our scheme,which shows that our scheme is practical.

Vectorial holography-mediated growth of plasmonic metasurfaces

Nowadays,the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries.However,engineering the properties of artificial materials at the nanoscale is challenging and costly.Here we demonstrate a facile and low-cost method for fabricating large-area silver nanoparticle metasurfaces(AgNPMSs)by using the vectorial holography-mediated growth technique.The AgNPMS,which can be regarded as a hologram device,possesses excellent chiroptical properties.The vectorial holographic technique may open avenues for fabricating novel chiroptical metamaterials with large degrees of freedom,which can be further used for beam steering,photocatalysis,biosensing,etc.

Experimental study of the optical fiber characteristics by digital hologram

The characteristics of optical fiber are quite important for improving the performance of optical fiber communication and sensor systems.Based on the Mach-Zehnder interferometer,a new measuring method is proposed and the digital holograms between the single mode fibers(SMFs) and specialty double-cladding(DC) fibers are analyzed.The experimental results show that the fringe density can be changed under the conditions of coaxial and off-axial interferences.Therefore it can be used to analyze the optical fiber characteristics including refractive index distribution,fiber modes,phase difference,etc.