基于目的管理的医疗信息系统隐私保护访问控制模型

随着智能化、开放性医院信息系统HIS(Hospital Information System)的出现,针对个人健康隐私信息的保护技术成为关注热点.在现有访问控制技术的基础上,结合现行HIS对于访问控制的需求,提出了HISPAC(HIS Privacy Access Control)模型.该模型引入目的管理概念,克服了现...     

Sensitivity Methods in the Dispatch and Siting of FACTS Controllers

Flexible AC transmission systems (FACTS) play an important role in improving the transfer capability and stability of a power system. In the application of voltage-sourced converter (VSC)-based FACTS controllers, it is important to study how a VSC impacts the flows in a power system. In this paper, we investigate this flow control problem using two sensitivity approaches, one using an injected voltage source formulation and the other an equivalent impedance formulation. The applications of sensitivity analysis for line active power redispatch and for new series VSC siting in a 1673-bus system are presented.     

中国CBN磨具的研发历程与技术发展趋势

本文回顾我国CBN磨具制造技术与产品的主要研发历程,以总结CBN磨具在结合剂体系、加工技术、品种规格等方面的主要发展特征。从市场结构和制造技术等方面对其未来发展趋势进行分析预测,并展望未来轴承行业等重点领域用CBN磨具及难加工材料磨削用CBN磨具的发展。      

低合金高强钢的强韧化机理与焊接性能

回顾了低合金高强度钢的发展历程,介绍了该类钢的强化机制、韧性机制以及焊接性能,并阐述了显微组织及合金元素对其性能的影响。采用微合金化成分设计与控轧控冷工艺相结合的方式,在传统强化方式基础上,在低合金高强钢中引入纳米沉淀相利用沉淀强化代替碳强化,使钢既保持了较高的强度和韧性,又提升了钢的焊接性能。     

油田产能建设钻井成本最优经济界限研究

在油田产能建设钻井过程中, 影响钻井成本经济界限的因素有钻井成本工艺技术和地质特征。为此, 运用技术经济学原理通过对影响油田钻井成本的因素进行分析, 建立了钻井成本经济界限与圈闭面积、 井深和单井日产量之间的数学模型。结合某油田的实际特征情况, 对评价模型的参数进行赋值, 测算了在不同圈闭面积、井深和单井日产量下的钻井成本。最后, 运用统计软件 Ｓ Ｐ Ｓ Ｓ对测算数据进行了分析, 得到了钻井成本与圈闭面积、 井深和单井日产量呈高度相关的关系, 并得到了以钻井成本为因变量, 以圈闭面积、 井深和单井日产量为自变量的线性相关模型。这对以后油田快速预测钻井成本, 科学制定钻井投标的价格有一定借鉴意义。     

Y1.7Er0.3Fe17快淬带的结构和磁熵变

采用熔体快淬法（铜辊速度为20 m/s）制备Y1.7Er0.3Fe17快淬带,通过X射线衍射仪、振动样品磁强计（VSM）和三维原子探针（3DAP）对样品的晶体结构、磁熵变和原子在三维空间中分布情况进行研究。结果表明,Y1.7Er0.3Fe17快淬带具有菱方Th2Zn17型结构,与标准PDF卡片（48-1454）相比较,Y2Fe17主相晶胞体积略减小;样品的居里温度在308 K附近,磁场变化为1.5 T,样品的最大磁熵变值为2.10 J·kg-1·K-1;Fe在晶界处含量略有降低,其它区域内,Y、Er和Fe 3种原子均匀分布在三维空间中。     

Location Method of Radioactive Source Based on Improved Particle Filtering

In order to use the autonomous mobile robot to search for unknown radioactive objects, a method for locating the radioactive source with improved particle filtering was proposed based on the recursive Bayesian estimation model. Firstly, an initial particle set was established, and the weight of the particle was updated and normalized according to the observation value. Secondly, the auto-optimal resampling method was introduced to increase the particle diversity in the resampling process. Finally, the particle carrying out the convergence condition was weighted and summed to estimate the position and activity parameters of the radioactive source. The simulation results show that the method is feasible and effective. The positioning accuracy is high in the unshielded environment, and the approximate position of the radioactive source can also be found in the shielded environment, which provides a reference for the final location of the radioactive source.     

水平地震力作用下钢筋混凝土预制单桩的可靠度分析

以工程中广泛应用的ｍ法，研究了高层建筑钢筋混凝土预制桩在水平地震力作用下的破坏性状，建立了单桩的功能函数，并分析了功能函数中各随机变量的概率模型和统计参数。最后以ＪＣ法和计算机模拟求得了可靠度。     

MR image reconstruction based on comprehensive sparse prior

In this paper, a novel Magnetic Resonance (MR) reconstruction framework which combines image-wise and patch-wise sparse prior is proposed. For addressing, a truncated beta-Bernoulli process is firstly employed to enforce sparsity on overlapping image patches emphasizing local structures. Due to its properties, beta-Bernoulli process can adaptive infer the sparsity (number of nonzero coefficients) of each patch, an appropriate dictionary, and the noise variance simultaneously, which are prerequisite for iterative image reconstruction. Secondly, a General Gaussian Distribution (GGD) prior is introduced to engage image-wise sparsity for wavelet coefficients, which can be then estimated by a threshold denoising algorithm. Finally, MR image is reconstructed by patch-wise estimation, image-wise estimation and under-sampled k-space data with least square data fitting. Experimental results have demonstrated that proposed approach exhibits excellent reconstruction performance. Moreover, if the image is full of similar low-dimensional-structures, proposed algorithm has dramatically improved Peak Signal to Noise Ratio (PSNR) 7～9 dB, with comparisons to other state-of-art compressive sampling methods.     

机器人铣削加工轨迹研究现状及发展趋势

工业机器人因其柔性强、灵活性高及感知能力强等优势,在复杂零件的高柔性制造中具有巨大潜力。加工轨迹是决定机器人铣削加工中加工效率和加工精度的重要因素。机器人加工轨迹规划除了要考虑数控加工中已有的问题,还要考虑机器人刚度、精度、稳定性等特有的问题,因此复杂性更高。从机器人铣削加工轨迹规划及优化方法出发,总结了近年来国内外学者在包括刚度强化、误差补偿、稳定性优化等方面的研究成果。最后对该领域的技术发展趋势进行了分析及展望。