基于FPGA的DDR3存储控制的设计与验证

DDR3SDRAM是第三代双倍数据传输速率同步动态随机存储器,DDR3具有高速率、低电压、低功耗等特点[1-2];在DDR3控制器的实际使用中,如何将用户需要存储的数据在DDR3中快速存储非常重要,如果数据被送到DDR3接口的速度低,则会影响DDR3的存储速度,同时影响DDR3的实际应用,因此,针对DDR3存储器设计存储控制有重要的意义[2];基于此设计主要分为低速读写控制与高速流读写控制,低速读写控制主要用于小数据量的操作,高速流读写控制主要用于批量数据的存储操作;此设计在FPGA上通过了大量数据读写的验证,证明数据存储的正确性;经过测试,在高速流读写模式下,DDR3存储控制设计的带宽利用率最大为66.4%;此设计在功能和性能上均符合系统总体设计的要求。     

系统资源受限环境下的证书解析方法研究

证书解析是证书应用的基础,目前已知的证书解析操作均运行于操作系统应用层。这种证书解析方法尽管具有较强的通用性,但代码复杂,占用系统资源较多。本文在研究证书格式的基础上,给出了一种适用于操作系统内核层、嵌入式系统等资源受限环境的解析方法,具有实现简单、占用资源少、运行速度快等特点。     

LM3S9896的μDMA高速网络驱动程序设计

针对Cortex—M3核的微控制器LM3S9896,提出了一种基于tzDMA的高速网络驱动程序的设计方案。在简要介绍LM3S9896的以太网控制器、网络驱动程序的作用后,对该网络驱动程序设计的各个部分进行了详细描述,包括网络驱动初始化程序、数据包发送程序、数据包接收程序和中断处理程序等。     

基于ARM-11的野外WSN基站设计与开发

无线传感器网络的应用日益广泛,然而在环境恶劣的野外,数据的采集与发送将受到很大的限制。而建立一个基站作为一个中继,可以很好地沟通节点和终端,从而在很大程度上提高数据的可靠性和有效性。此外,对于不同类型的数据,采用自适应方式选择传输网络进行传输,也可以充分利用有限的网络资源来提高效率。     

Virtual reflected-light microscopy

Research on better methods to digitally represent microscopic specimens has increased over recent decades. Opaque specimens, such as microfossils and metallurgic specimens, are often viewed using reflected light microscopy. Existing 3D surface estimation techniques for reflected light microscopy do not model reflectance, restricting the representation to only one illumination condition and making them an imperfect recreation of the experience of using an actual microscope. This paper introduces a virtual reflected-light microscopy (VRLM) system that estimates both shape and reflectance from a set of specimen images. When coupled with anaglyph creation, the system can depict both depth information and illumination cues under any desired lighting configuration. Digital representations are compact and easily viewed in an online setting. A prototype used to construct VRLM representations is comprised only of a microscope, a digital camera, a motorized stage and software. Such a system automatically acquires VRLM representations of large batches of specimens. VRLM representations are then disseminated in an interactive online environment, which allows users to change the virtual light source direction and type. Experiments demonstrate high quality VRLM representations of 500 microfossils.     

The effect of vacancies on the annular dark field image contrast of grain boundaries: a SrTiO(3) case study

The analysis of grain boundary structure in high resolution electron microscopy is often hindered by contrast variation within the grain boundary region which is not explained by simple models of the grain boundary structure. Recent work suggests that structural disorder along the beam direction and the presence of vacancies contribute significantly to this effect. One might expect a significant reduction in contrast in a Z-contrast image of a grain boundary would imply that vacancies present must result from the absence of heavier elements. Using a [001](210) Σ5 grain boundary in SrTiO₃ as a test case and first principles structure relaxation to calculate stable defect structures, we show that the reduction in the intensity from fully occupied Sr columns due to the structural distortion resulting from a nearby O vacancy can be as great as that due to introducing a Sr vacancy in the column itself. The effect on energy dispersive X-ray spectroscopy signals is also considered, but found to be smaller than that on Z-contrast images.     

Key-dependent 3D model hashing for authentication using heat kernel signature

Multimedia-based hashing is considered an important technique for achieving authentication and copy detection in digital contents. However, 3D model hashing has not been as widely used as image or video hashing. In this study, we develop a robust 3D mesh-model hashing scheme based on a heat kernel signature (HKS) that can describe a multi-scale shape curve and is robust against isometric modifications. We further discuss the robustness, uniqueness, security, and spaciousness of the method for 3D model hashing. In the proposed hashing scheme, we calculate the local and global HKS coefficients of vertices through time scales and 2D cell coefficients by clustering HKS coefficients with variable bin sizes based on an estimated L² risk function, and generate the binary hash through binarization of the intermediate hash values by combining the cell values and the random values. In addition, we use two parameters, bin center points and cell amplitudes, which are obtained through an iterative refinement process, to improve the robustness, uniqueness, security, and spaciousness further, and combine them in a hash with a key. By evaluating the robustness, uniqueness, and spaciousness experimentally, and through a security analysis based on the differential entropy, we verify that our hashing scheme outperforms conventional hashing schemes.     

Bare finger 3D air‐touch system with embedded multiwavelength optical sensor arrays for mobile 3D displays

A camera‐free 3D air‐touch system was proposed. Hovering, air swiping, and 3D gestures for further interaction with the floated 3D images on the mobile display were demonstrated. By embedding multiwavelength optical sensors into the display pixels and adding angular‐scanning illuminators with multiwavelength on the edge of the display, the flat panel can sense images reflected by a bare finger from different heights. In addition, three axis (x, y, z) information of the reflected image of the fingertip can be calculated. Finally, the proposed 3D air‐touch system was successfully demonstrated on a 4‐inch mobile 3D display.     

An introduction to the Information Display Measurement Standard 1, the first display measurement standard from the International Committee for Display Metrology

On June 1, 2012, the Information Display Measurement Standard version 1 was released. This is the first standard from the worldwide standard group, the International Committee for Display Metrology, a standards committee within SID, and it culminates several years worth of development from many contributors at various levels. It has 26 top‐level chapters and a total over 450 sections of all parts, including over 200 measurement sections and 8 appendices that cover 133 topics of display metrology, tutorials, technical discussions, and references. Herein is an overview of the Information Display Measurement Standard version 1, including the structure of the document, tips, tricks, and hidden features, how it is maintained, support material, a breakdown of its contents, and finally, a sampling of four of the over 200 measurements. The standard is available as a free download and can be found on the International Committee for Display Metrology home page — http://www.icdm‐sid.org .     

Particle filters and occlusion handling for rigid 2D–3D pose tracking

In this paper, we address the problem of 2D–3D pose estimation. Specifically, we propose an approach to jointly track a rigid object in a 2D image sequence and to estimate its pose (position and orientation) in 3D space. We revisit a joint 2D segmentation/3D pose estimation technique, and then extend the framework by incorporating a particle filter to robustly track the object in a challenging environment, and by developing an occlusion detection and handling scheme to continuously track the object in the presence of occlusions. In particular, we focus on partial occlusions that prevent the tracker from extracting an exact region properties of the object, which plays a pivotal role for region-based tracking methods in maintaining the track. To this end, a dynamical choice of how to invoke the objective functional is performed online based on the degree of dependencies between predictions and measurements of the system in accordance with the degree of occlusion and the variation of the object’s pose. This scheme provides the robustness to deal with occlusions of an obstacle with different statistical properties from that of the object of interest. Experimental results demonstrate the practical applicability and robustness of the proposed method in several challenging scenarios.