ZnO and Ag-doped ZnO nanorods are fabricated by hydrothermal method. Effects of Ag doping on the ZnO nanorods have been investigated by various measurements. Introduction of Ag in ZnO nanorods has no effects on the surface morphology and growth habits of ZnO. Compared to ZnO nanorods, absorption wavelength shifts red after Ag doping, corresponding to decrease of optical band gap. It is suggested that defects band is introduced into Ag-doped ZnO. Luminescence of Ag-doped ZnO nanorods have been found to have two emission peaks centering at around 520 nm and 680 nm, which can be explained by oxygen vacancy and introduced defects, respectively. ZnO and Ag-doped ZnO nanorods inorganic/organic heterostructure LEDs are reported. The junction consists of nanorods and polymer, which is evaporated or spin-coated on the samples. Ag doping ZnO nanorods inorganic/organic heterostructure LED shows smaller leakage current and better rectification characteristic than pure ZnO nanorods LED device.
Object-order volume rendering algorithms play important part in many visualization applications for their excellent performances. Though many volume rendering algorithms have been proposed during the past two decades, most of them are image-order algorithms. Splatting, one of the classical object-order algorithms, suffers from several kinds of aliasing artifacts for inaccuracy reasons. A much accurate object-order volume rendering algorithm is presented in this paper. By defining a set of data structures to serve as two step reconstruction lookup tables, together with using a simple voxel traversal and resample strategy, the new algorithm can not only get rid of inaccuracy of traditional splatting, but also have the features including high cache hit rate, easy to implement of parallelism and high speedup from pre-processing.
Volume rendering has been a key technology in the visualization of data sets from various disciplines. However, real-time volume rendering of large scale data sets is still a challenging field due to the vast memory, bandwidth and computational requirements. In this paper, to visualize small to medium scale data set in real-time, we first proposed a new kind of volume rendering graphic processor based on object-order splatting algorithm in which flexible transfer function configuration and software optimization such as early opacity termination and transparent voxel occlusion can be achieved. At the same time, the processor also integrates an eight-way interleaved memory system and an efficient address calculation module to accelerate the voxel traversal process and maintain high cache hit rate. Multiple parallel rendering pipelines embedded also can achieve local parallelism on board. Second, in order to render large scale data sets, a real-time and general-purpose volume rendering architecture is also presented in this paper. By utilizing graphic processors on PC clusters, large scale data sets can be visualized resulted from the high parallel speedup among graphic processors.
This paper presents a simple method to calibrate the intrinsic parameters of zoom-lens digital cameras. This method combines the classical calibration algorithm using a planar pattern and the Exchangeable Image File Format (EXIF) metadata of image files captured by digital cameras. The EXIF metadata records many information about the camera’s setting such as the focal length of zooming lens. So we can use the focal length from EXIF to know the zoom lens setting. Firstly, a pre-calibration should be done to know the relationship between zoom lens settings and the intrinsic camera parameters. We take some sample lens settings from the minimum focal length to the maximum one by changing the lens zooming positions, and perform the mono focal calibration for each lens setting configuration. Then we get the coefficients of the polynomial function through curve fitting. After that we can get the intrinsic parameters correspond with the zoom lens setting of new image files shoot by this digital camera. Our experiments show the proposed method can provide accurate intrinsic camera parameters for all the lens settings continuously.