Advanced Materials Research Vols. 850-851

Abstract: In this paper, we discuss the temperature control system of thermoelectric cooler. It is controlled by MSP430F149. We achieve the sample temperature by using Pt100 resistance. We make the temperature controlled by using the cooling chip. We can set the temperature, display the working status and draw real-time temperature curve by using the keyboard and LCD.

Abstract: This paper designs and implements an information hiding algorithms by using the equivalent characteristics of attributes and sub-elements in the XML document. Experimental results show that the algorithm has large information hiding capacity, better hiding features and robustness.

Abstract: E-commerce websites has abundant commercial data. Some very beneficial information to the analysis and prediction of the market can be discovered from these data by applying data mining techniques. The topic-focused web crawler can crawl and gather the subject-related web pages as soon as possible. This thesis has designed and realized the topic-focused crawler based on Scrapy. It firstly introduces the design idea of the crawler and highlights the functions of Scrapys every part. Then, it uses this topic-focused crawler to realize the capture of information from the C2C e-commerce platform, for example TaoBao. At last, it obtains the running result and comparisons of crawling performance between Scrapy based crawler and general crawler.

Abstract: With the development of the times and the increasing mobility of the population, the situation of public environmental safety is becoming more and more serious. So an intelligent video monitoring system is designed in order to better carry out constantly effective monitoring for the public environment. In this paper, the IT Company DM8168 as the core of hardware designs an intelligent video surveillance system to realize the function of video capture, encoding, transmission, storage and so on. Besides, it will carry out motion detection in the aspect of intelligence. The main tasks can be completed as follows, first, architecture and front-end network camera hardware design of intelligent video system requires single-stream network. Second, the design of intelligent video system software, which is to complete the overall software design flow chart. Clients using the media player on the PC front-end network camera based on Davinci platform development. Third, algorithm design of intelligent software system is to study of the moving object detection algorithm and provide the algorithm effect diagram.

Abstract: In this paper, the development and analysis of Police Location System by GPRS wireless communication are researched, a new Distribute Police Location System which adopts the method that transmits data algorithm is WMMP(wireless machine management protocol) is designed. The packet loss rate of the system can be controlled very well, thus, a better efficiency is achieved. The Police Location System is composed of locating terminal and software with GIS and E-Map. The location system for police establishes a IDs network for policemen, who is out for emergency, it can ensure the safety of policemen and supply surveillances for the policemen during their mission. Details of the system are discussed below.

Abstract: Aimed at the characteristics of indoor application environment, a real-time wireless monitoring system for indoor air quality based the nRF24L01 and GSM network was proposed. The system built the star subnet structure with nRF24L01 wireless module, used GSM module SIM300 to complete wireless communication between the subnet and GSM network, and achieved GSM network users to remotely monitor indoor air quality. The subnets with master-slave structure mode, which was constituted by the control terminal and multiple data collection terminals, implemented indoor air quality concentration and temperature and humidity data real-time acquisition with the centralized control method. The experimental results show that the subnets can real-time finish wireless data transmission within a distance of 700 meters, and the system with simple structure and stable work can realizes real-time monitoring of indoor air quality.

Abstract: With the development of the Internet and relative information technologies, more and more requirements are urgently needed by power system monitoring unit. By analyzing traditional wired power system monitoring unit, this paper elaborates on power system monitoring unit based on ZigBee, focusing on the design of monitoring node, including both hardware and software. And this paper completely discusses suitable solution for wireless power system monitoring unit, hardware and software design of the systems nodes for collecting and coordinating, and a right project for wireless power monitoring system.

Abstract: The visible light communication (VLC) technology based on the lighting system of space station is put forward. The VLC has advantages of not taking up radio spectrum, no electromagnet interference and radiation, high emission power and good secrecy. This paper mainly studies to improve inter-symbol interference and fading problem caused by multipath effects in VLC system using RAKE receiving technology. The simulation results in this paper indicate that optical receiving technology utilizing RAKE can not only resolve the inter-symbol interference and reduce the bit error rate (BER), but also improve the signal to noise ratio of the system output.

Abstract: This thesis designs a new model of thermal control circuit based on the in-depth study on the temperature control of laser, in order to make laser to work under a constant temperature. This circuit uses ADN8831 as the key chip, combines PWM control scheme. It has accomplished the design of input stage, compensative links, output stage, filter circuit, protection and fault detection of hardware circuit. After actual laser experiments, the precision of temperature can be controlled up to 0.01°C. Experiments show that this circuit is of high efficiency, small size, high reliability, and strong driving ability. It will provide constant temperature control for laser device.

Abstract: Visible light communication system using light emitting diode as light source, the system has the dual role of lighting and communication, thereby greatly saving energy .The bandwidth of LED modulation is a major obstacle to development of VLC technology. Researchers have put forward a variety of techniques to extend the modulation bandwidth and improve the transmission rate, such as Blu-ray filtering, equalization, multiple-input multiple-output (MIMO) technology, high ray modulation format, the wavelength division multiplexing technology, discrete multi-tone modulation and so on. The transmission rate of VLC system can be greatly improved by a combination of these techniques in a technical or several techniques. This paper analyzes the effect of OFDM technology each sub-carrier modulation with MQAM to visible light communication. It gives a brief introduction of the visible light communication system; it also shows the average power spectral density and error rate from SIMULINK simulation. It proves further the high-level quadrature amplitude modulation (MQAM) with higher bandwidth efficiency and smaller error rate, the bandwidth efficiency of 256QAM modulation is the twice of 16QAM modulation.