Papers by Author: Shu Ying Cheng

Abstract: This article presents a new design and implementation of a robust and efficient embedded image system which can perform image acquisition, data saving and communication. The system hardware consists of processors of CPLD and ARM, an OV7620 digital camera, an ISSI SRAM and some peripheral interfaces. The key part of the software is the usage of analogous DMA storage and processing technology which makes the image system have a higher efficiency. A memory allocation algorithm is developed to maximize parallel data access and make the utmost use of ARM’s processing ability, thus improving the system performance. Furthermore, a simple practical binary image processing algorithm is developed to enhance the performance of image processing in this article. The experimental result shows that the proposed design approach for a low cost embedded image system can achieve high performance, robustness and efficiency.

Abstract: China mobile is using 3G and WiFi to construct a everywhere wireless network ,named wireless city.The lighting management system make every city lighting unit to access a unified management platform via the wireless network, so that realize the acquisition of working state, the setting of work mode and the automatic report of fault for every lighting unit. This paper mainly introduces the lighting management node and the unified management platform. The lighting management node is responsible for adaptive wireless network access, information collection and control of the lighting unit. The unified management platform is responsible for establishing the feature database of every light unit, the man-machine operation interface and the illumination energy conservation algorithm of the whole city. In addition, this paper also discussed the cost,and efficiency, the advantages and disadvantages of the lighting management system. Finally, through the experiment estimate for an intermediate city, This system can yield high rates of energy usage, with pay back in 10 years.

Abstract: Metallic-doping chalcogenide compounds have attracted significant interest in application of photovoltaic devices recently. In this article, Al-doped SnS films with a thickness of about 500 nm have been deposited on glass substrates by thermal evaporation technique. Al-doping concentration (from 0 at. % to 15 at.%) in the SnS films can be controlled accurately by varying Al layer thickness. The effects of Al–doping on the physical properties of the films have been investigated by X-ray diffraction, scanning electron microscopy, ultraviolet-visible-near infrared spectroscopy measurements and Hall effect measurement system. All the films are orthorhombic SnS with preferred (111) crystallites orientation, and they are of p-type conductivity. With the increasing of Al-doping concentration, the evaluated direct band gap Edir of the SnS: Al films decreases from 1.50eV to 1.29eV and the conductivities of the films increase. Therefore, the optical and semiconducting properties of the SnS films have been improved by Al-doping.

Abstract: Silver-doping in SnS films can improve the semiconducting properties of SnS films. Based on our previous research, SnS:Ag thin films were deposited on ITO coated glass by pulse electro-deposition in order to study their structural, optical and electrical properties. SnS:Ag thin films were characterized with X-ray diffraction (XRD) , Scanning Electron Microscope (SEM) and some other methods. The primary composition of the films is SnS, but maybe there is a little quantity of SnS2, Ag8SnS6 and other compounds. The doped films exhibit good crystallization with big grain size. They have an optical gap of 1.66~1.89eV and a high absorption coefficient (α＞5×104cm-1). Hall measurement has shown that all the samples are of p-type conduction with low resistivity of the order of 10-3Ω•cm, and the carrier concentration increases to 1019cm-3 after Ag-doping. In conclusion, the semiconducting properties of the SnS films have been improved by silver-doping. Thus, SnS:Ag thin films can be used as solar cells absorbers.

Abstract: SnS and Ag films were deposited on glass substrates by vacuum thermal evaporation successively, then they were annealed in N2 ambience at a temperature of 300 oC for 2h. By controlling the Ag evaporation voltage to roughly alter content of Ag in SnS films, different Ag-doped SnS films were obtained. The microstructures, composition and properties of the films were characterized with X-ray diffraction ( XRD ), atomic force microscopy(AFM) and some other methods. With the increase of Ag evaporation voltage (VAg), there exist new phases of Ag8SnS6 and Ag2S, whose intensity of diffraction peaks increases with the increasing Ag-dopant, and the average roughness of the films varies from 18.7nm to 23.6nm, and grain size increases from 192nm to 348nm. With the increase of VAg, the evaluated direct band gap Eg of the films decreases from 2.28eV(undoped) to 2.05eV (VAg=70V), the carrier concentration value and Hall mobility of the films diminishes from 2.048×1014cm-3 and 25.96 cm2.v-2.s-1 to 1.035×1016 cm-3 and 5.66 cm2.v-2.s-1, respectively; while the resistivity of the films decreases sharply from 1174Ω.cm(undoped ) to 107Ω.cm (VAg=70V ). All the films are of p-type conductivity. The above results show that the semiconducting properties of the SnS films have been improved by silver-doping.