粒子群属性聚类的位置隐私保护

针对基于位置服务中连续查询情况下，用户自身属性信息很容易被攻击者获取，并通过关联获得用户位置隐私的情况，提出了一种利用粒子群聚类加速相似属性用户寻找，并由相似属性匿名实现用户位置泛化的隐私保护方法。该方法利用位置隐私保护中常用的可信中心服务器，通过对发送到中心服务器中的查询信息进行粒子群属性聚类，在聚类的过程中加速相似属性用户的寻找过程，由相似属性用户完成位置泛化，以此实现位置隐私保护。实验结果证明，这种基于粒子群属性聚类的隐私保护方法具有高于同类算法的隐私保护能力，以及更快的计算处理速度。     

A time-aware searchable encryption scheme for EHRs

Despite the benefits of EHRs (Electronic Health Records), there is a growing concern over the risks of privacy exposure associated with the technologies of EHR storing and transmission. To deal with this problem, a time-aware searchable encryption with designated server is proposed in this paper. It is based on Boneh's public key encryption with keyword search and Rivest's timed-release cryptology. Our construction has three features: the user cannot issue a keyword search query successfully unless the search falls into the specific time range; only the authorized user can generate a valid trapdoor; only the designated server can execute the search. Applying our scheme in a multi-user environment, the number of the keyword ciphertexts would not increase linearly with the number of the authorized users. The security and performance analysis shows that our proposed scheme is securer and more efficient than the existing similar schemes.     

JPEG encryption for image rescaling in the encrypted domain

This work proposes a novel protocol of encrypting the JPEG image suitable for image rescaling in the encrypted domain. To protect the privacy of original content, the image owner perturbs the texture and randomizes the structure of the JPEG image by enciphering the quantized Discrete Cosine Transform (DCT) coefficients. After receiving the encrypted JPEG image, the service provider generates a rescaled JPEG image by down-sampling the encrypted DCT coefficients. On the recipient side, the encrypted JPEG image rescaled by the service provider can be decrypted to a plaintext image with a lower resolution with the aid of encryption keys. Experimental results show that the proposed method has a good capability of rescaling the privacy-protected JPEG file.     

Application of Vis–NIR hyperspectral imaging in classification between fresh and frozen-thawed pork Longissimus Dorsi muscles

Fresh and frozen-thawed (F-T) pork meats were classified by Vis–NIR hyperspectral imaging. Eight optimal wavelengths (624, 673, 460, 588, 583, 448, 552 and 609 nm) were selected by successive projections algorithm (SPA). The first three principal components (PCs) obtained by principal component analysis (PCA) accounted for over 99.98% of variance. Gray-level-gradient co-occurrence matrix (GLGCM) was applied to extract 45 textural features from the PC images. The correct classification rate (CCR) was employed to evaluate the performance of the partial least squares-discriminate analysis (PLS-DA) models, by using (A) the reflected spectra at full wavelengths and (B) those at the optimal wavelengths, (C) the extracted textures based on the PC images, and (D) the fused variables combining spectra at the optimal wavelengths and textures. The results showed that the best CCR of 97.73% was achieved by applying (D), confirming the high potential of textures for fresh and F-T meat discrimination.     

Oriented total variation l1/2 regularization

Total Variation (TV) is a widely used image restoration/decomposition model. It is observed that the classical TV l1 and TV l2 regularization, on the one hand, do not favor higher-gradient structures over lower-gradient details as expected for structure preserving image processing, and on the other hand, tend to reduce the horizontal and vertical gradients, and thus inevitably blur the oblique edges in images. In this paper, we address these two problems by defining Oriented Total Variation l1/2 (OTV l1/2). It is theoretically and experimentally demonstrated that applying l1/2 regularization to the directional derivatives of images leads to superior structure preservation. OTV l1/2 regularization can be applied to image denoising and video compression, and the experimental results verify that OTV l1/2 outperforms other similar models.     

更新度——城市改造的合理性思考

更新度是改造合理性的表现，它包含现状的保留程度和改造后达到的程度两个方面。分析了城市改造中失度的现象，探讨了更新度的基本理论问题，以期在更新中合理把握“度”，提高改造的合理性。     

浅谈水泥稳定土的工程应用

从使用工艺注意事项、养生原则以及原材料要求等方面对水泥稳定土材料进行了介绍，对推广应用此类结构在工程上的应用具有一定的意义。     

空间基因

在形态类型相关研究基础上,从城市空间发展理论的视角,提出"空间基因"概念。空间基因是独特的、相对稳定的空间组合模式,它既是城市空间与自然环境、历史文化长期互动契合与演化的产物,承载着不同地域特有的信息,形成城市特色的标识,又起着维护三者和谐关系的作用。通过空间基因识别提取、解析评价到传承导控的技术体系,可以避免采用统一的模式面对千差万别城市、不尊重历史和自然的设计弊端,强化规划设计的在地性,推动城市规划设计方法从空间形式创作到空间基因分析的方向性转变,为城市建设与自然保护、文化传承的共赢提供有效设计路径。文章还对空间基因库计划进行了展望。     

求任意两曲面相贯线及特殊点的新方法

对任意两曲面相贯，求作相贯线及特殊点的投影，采用数学上的“结式”．计算准确，不受曲面种类的限制．     

局部时差约束邻域保持嵌入算法在故障检测中的应用

传统的邻域保持嵌入(neighborhood preserving embedding,NPE)算法通过k近邻(k-nearest neighbors,k-NN)方法选择邻域进行重构来实现降维。但在实际工业过程中采集的样本具有时序相关性,仅仅通过欧氏距离选择近邻样本不能充分反映数据中包含的信息,从而影响检测效果。因此,提出一种局部时差约束邻域保持嵌入(local time difference constrained neighborhood preserving embedding,LTDCNPE)算法,充分考虑样本间的时间和空间关系,从而建立准确的故障检测模型。首先,该算法在固定尺度的时间窗内,根据样本的时序关系和空间特征挑选出邻域。其次,利用样本间的时间差异为邻域样本进行加权,使数据特征保留了高维空间的局部结构。然后,对降维后得到的主元空间和残差空间构建T^{\mathrm{2}}和SPE统计量并确定控制限。最后,通过数值例子和Tennessee-Eastman(TE)过程仿真验证LTDCNPE算法的有效性。