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排序方式: 共有696条查询结果,搜索用时 15 毫秒
1.
对访问控制机制中存在的安全性和有效性的问题进行了研究,提出了基于访问树剪枝的属性加密ATP-ABE(Access Tree Pruning Attribute Based Encryption)的访问控制方案。当ATP-ABE算法需要访问它的树型结构访问策略时,通过剪枝处理访问树结构中包含用户ID属性节点的分支,提高了用户所有者DO(Data Owner)管理和控制属性的效率,更加有效地实现了数据共享。还为访问树结构设计了许可访问属性,使DO仍保留共享数据的关键属性,并且能够完全控制它们的共享数据。基于决策双线性密钥交换算法DBDH(Decisional Bilinear Diffie-Hellman)假设分析了ATP-ABE方案的安全性,研究结果表明与两种经典ABE方案比较,ATP-ABE更加有效地减少了算法的系统设置、私钥生成、密文大小、用户属性撤销以及加解密过程中的计算开销,并给出了定量结论。  相似文献   
2.
Modelling flow phenomena and their related weathering effects is often cumbersome due their dependence on the environment, materials and geometric properties of objects in the scene. Example‐based modelling provides many advantages for reproducing real textures, but little effort has been devoted to reproducing and transferring complex phenomena. In order to produce realistic flow effects, it is possible to take advantage of the widespread availability of flow images on the Internet, which can be used to gather key information about the flow. In this paper, we present a technique that allows the transfer of flow phenomena between photographs, adapting the flow to the target image and giving the user flexibility and control through specifically tailored parameters. This is done through two types of control curves: a fitted theoretical curve to control the mass of deposited material, and an extended colour map for properly adapting to the target appearance. In addition, our method filters and warps the input flow in order to account for the geometric details of the target surface. This leads to a fast and intuitive approach to easily transfer phenomena between images, providing a set of simple and intuitive parameters to control the process.  相似文献   
3.
杨洋  王汝传 《计算机应用》2020,40(5):1364-1368
为了解决基于位置的服务(LBS)和增强现实(AR)技术快速发展带来的用户位置隐私泄露的隐患,分析了现有的位置隐私保护方法的优缺点,提出基于位置安全性的位置隐私保护方法。将区域安全度和伪装区域引入该方法中,将提示某区域是否需要保护这一度量标准定义为区域安全度,非安全区域(即需要给予保护的区域)的区域安全度设置为1,安全区域(即不需要保护的区域)设置为0,通过扩大区域安全度和识别等级来计算位置安全度。实验结果表明,该方法与未引入位置安全性的方法相比降低了平均定位误差,提高了平均安全性,从而有效地保护了用户的位置隐私,提高了LBS的服务质量。  相似文献   
4.
Target design methodologies (DfX) were developed to cope with specific engineering design issues such as cost-effectiveness, manufacturability, assemblability, maintainability, among others. However, DfX methodologies are undergoing the lack of real integration with 3D CAD systems. Their principles are currently applied downstream of the 3D modelling by following the well-known rules available from the literature and engineers’ know-how (tacit internal knowledge).This paper provides a method to formalize complex DfX engineering knowledge into explicit knowledge that can be reused for Advanced Engineering Informatics to aid designers and engineers in developing mechanical products. This research work wants to define a general method (ontology) able to couple DfX design guidelines (engineering knowledge) with geometrical product features of a product 3D model (engineering parametric data). A common layer for all DfX methods (horizontal) and dedicated layers for each DfX method (vertical) allow creating the suitable ontology for the systematic collection of the DfX rules considering each target. Moreover, the proposed framework is the first step for developing (future work) a software tool to assist engineers and designers during product development (3D CAD modelling).A design for assembly (DfA) case study shows how to collect assembly rules in the given framework. It demonstrates the applicability of the CAD-integrated DfX system in the mechanical design of a jig-crane. Several benefits are recognized: (i) systematic collection of DfA rules for informatics development, (ii) identification of assembly issues in the product development process, and (iii) reduction of effort and time during the design review.  相似文献   
5.
文章指出,70后中国建筑师站在计算机带来的新技术变迁的时代前沿从电脑普及化到电脑计算化,首当其冲受到技术革命带来的设计方法和过程改变的洗礼,从而对数字设计具有敏锐触觉。70后受到的教育延续布扎体系,深悉建筑本质:几何形态、空间、质感,光线和建构。"建房子"的迫切需求让70后的数字时代的建筑观具有强烈实用主义的特征,这样的特征给在中国建筑实践和教育中崛起的70后带来了产生新建筑形态语言和思潮可能的机会。  相似文献   
6.
采用核磁共振仪、傅里叶红外光谱仪、热重分析仪、差示扫描量热仪和力学测试等手段,研究了煤基均聚聚丙烯1100N及对比牌号链结构等微观结构、结晶行为、热性能及力学性能等。结果表明,与市场石油基同类产品相比,煤基均聚聚丙烯1100N具有链结构缺陷低、等规度高、易结晶、耐热性能和刚性好的优势,但抗冲击性能略低于同类产品。  相似文献   
7.
This paper presents an innovative solution to model distributed adaptive systems in biomedical environments. We present an original TCBR-HMM (Text Case Based Reasoning-Hidden Markov Model) for biomedical text classification based on document content. The main goal is to propose a more effective classifier than current methods in this environment where the model needs to be adapted to new documents in an iterative learning frame. To demonstrate its achievement, we include a set of experiments, which have been performed on OSHUMED corpus. Our classifier is compared with Naive Bayes and SVM techniques, commonly used in text classification tasks. The results suggest that the TCBR-HMM Model is indeed more suitable for document classification. The model is empirically and statistically comparable to the SVM classifier and outperforms it in terms of time efficiency.  相似文献   
8.
To design a workflow process that is efficient, meaningful, and understandable it is important to properly consider how to compose the activities it will consist of. In this paper, guidelines are presented for this exact purpose. These focus on the elementary data-processing steps that are at the core of a workflow process. The guidelines help to determine the relative importance of these data-processing steps as well as their relatedness, such that activities can be composed in a fully automated manner. We implemented this approach in freely available software. A thorough evaluation that incorporates real-life workflow designs indicates that the use of these guidelines leads to activities that closely resemble those designed by experienced modelers. As such, the proposed guidelines provide a proper and automated alternative to what is otherwise a complex and time-consuming task.  相似文献   
9.
This paper presents a new depth image recovery method for RGB-D sensors giving a complete, sharp, and accurate object shape from a noisy boundary depth map. The proposed method uses the image guided Total Generalized Variation (TGV) with the depth confidence. A new directional hole filling method of view synthesis is also investigated to produce natural texture in hole regions whereas reducing blurring effect and preventing distortion. Thus, a high-quality image view can be achieved. Experimental results show that the proposed method yields higher quality recovered depth maps and synthesized image views than other previous methods.  相似文献   
10.
Hybridization in optimization methods plays a very vital role to make it effective and efficient. Different optimization methods have different search tendency and it is always required to experiment the effect of hybridizing different search tendency of the optimization algorithm with each other. This paper presents the effect of hybridizing Biogeography-Based Optimization (BBO) technique with Artificial Immune Algorithm (AIA) and Ant Colony Optimization (ACO) in two different ways. So, four different variants of hybrid BBO, viz. two variants of hybrid BBO with AIA and two with ACO, are developed and experimented in this paper. All the considered optimization techniques have altogether a different search tendency. The proposed hybrid method is tested on many benchmark problems and real life problems. Friedman test and Holm–Sidak test are performed to have the statistical validity of the results. Results show that proposed hybridization of BBO with ACO and AIA is effective over a wide range of problems. Moreover, the proposed hybridization is also effective over other proposed hybridization of BBO and different variants of BBO available in the literature.  相似文献   
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