Derivation and analysis of a filtered backprojection algorithm for cone beam projection data

The authors address the problem of three-dimensional image reconstruction from cone beam projections. Modifying a result due to A.A. Kirillov (Soviet Math. Dokl., vol. 2, p.268-9, 1961), the authors derive an inversion formula for the case where the cone vertices form an unbounded curve. For the special case in which the cone vertices form a circle, an approximate reconstruction formula is developed and shown to be essentially equivalent to the practical cone-beam algorithm of L.A. Feldkamp et al. (1984). For this approximate inverse, the authors derive the resulting spatially varying point spread function, examine the effect of bandlimiting due to sampling, and compare the resulting image quality as a function of the radius of the circle formed by the cone vertices.     

Fast‐moving coin recognition using deep learning

Multimedia Tools and Applications - Deep learning has made essential contributions to the development of visual object detection and recognition. Identifying fast-moving objects from the viewpoint...     

Image super-resolution using supervised multi-scale feature extraction network

Multimedia Tools and Applications - Image super-resolution using deep convolutional networks have recently achieved great successes. However, previous studies have failed to consider the spatial...     

基于粒子群优化BP神经网络的超声波缺陷位置预测

海洋设备的无损检测对于保障设备安全使用至关重要,由于设备所处的海洋环境特殊,要实现对海洋设备缺陷位置的准确估计难度较大.论文提出了一种基于粒子群优化BP神经网络(PSO-BP)预测设备缺陷位置的方法.通过模拟了海洋检测环境,用钢板作为实验对象,用超声波探伤仪对缺陷钢板进行了数据采集,获取了水下钢板的实时数据.通过粒子群算法对BP网络进行优化后对数据进行分析,对比缺陷出现的实际位置和预测位置,证明了粒子群优化的BP神经网络对于超声波检测的缺陷出现位置具有较好的预测效果.     

Differences in electrochemical corrosion behaviours between selective laser melted and wrought Ti6Al4V alloys in acid fluoride-containing artificial saliva

Journal of Applied Electrochemistry - In this work, the electrochemical corrosion behaviours of selective laser melted (SLMed) and wrought Ti6Al4V alloys in acid fluoride-containing artificial...     

IDEF0法建立模具CAD／CAM系统的功能模型

本文阐述了 IDEFO 法建立系统功能模型的步骤、方法和意义,IDEFO 法是一种结构化的系统分析方法,最后用一个简单实例加以说明。     

汽车用磁性材料和磁性器件

汽车前灯装置用的磁性材料为了减少汽车夜间行驶的交通事故,一个重要的办法就是提高驾驶员的眼睛的夜间辨认能力,这就要在汽车上安装高亮度前灯（High Intensity Dischrge Lamp,简写为HID灯）,这种灯较传统用的卤灯省电且更亮,这样驾驶员就能借助它容易发现路面障碍物.HID灯是水银灯、金属卤化物灯、高压钠灯的统称.其中金属卤化物灯用作汽车前灯有2个缺点：①从点灯至达到规定亮度需数分至数十分钟;②一旦灯灭,再点着也必需数分至数十分钟.为克服这两点缺点在其点灯电路中必须设置变换器和触发器.     

Quantum state transfer between an optomechanical cavity and a diamond nuclear spin ensemble

We explore an efficient scheme for transferring quantum state between an optomechanical cavity and nuclear spins of nitrogen-vacancy centers in diamond, where quantum information can be efficiently stored (retrieved) into (from) the nuclear spin ensemble assisted by a mechanical resonator in a dispersive regime. Our scheme works for a broad range of cavity frequencies and might have potential applications in employing the nuclear spin ensemble as a memory in quantum information processing. The feasibility of our protocol is analyzed using currently available parameters.     

Practical chosen-ciphertext secure Hierarchical Identity-Based Broadcast Encryption

We focus on practical Hierarchical Identity-Based Broadcast Encryption (HIBBE) with semantic security against adaptively chosen-ciphertext attacks (CCA2) in the standard model. We achieve this goal in two steps. First, we propose a new HIBBE scheme that is secure against chosen-plaintext attacks (CPA). Compared with the existing HIBBE scheme that is built from composite-order bilinear groups, our construction is based on prime-order bilinear groups. The much better efficiency of group operations in prime-order bilinear groups makes our proposed HIBBE scheme more practical. Then, we convert it into a CCA2-secure scheme at the cost of a one-time signature. Instead of extending one user hierarchy in the Canetti–Halevi–Katz approach from CPA-secure (\(l+1\))-Hierarchical Identity-Based Encryption [(\(l+1\))-HIBE] to CCA2-secure \(l\)-HIBE, our construction merely adds one on-the-fly dummy user in the basic scheme. We formally prove the security of these two schemes in the standard model. Comprehensive theoretical analyses and experimental results demonstrate that the proposed HIBBE schemes achieve desirable performance.