![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
With the development of smartphones and mobile Internet, the demand for navigation and location services is increasing. In a complex and large indoor environment such as a library, readers often need to determine the location of mobile terminals and items indoors, and require libraries to provide navigation services. Take the Chang'an Campus Library of Northwestern Polytechnical University as an example. It covers an area of ​​32,000 square meters. In such a huge indoor space, it is necessary to find the necessary books and materials. Even with the help of traditional road signs and cataloging information, it is not for the readers. A simple thing.
If there is a library indoor navigation service, the reader only needs to input the required library information on the mobile phone. The library indoor navigation service system can display the reader from the current location to the target by positioning the reader indoors and combining the map information. Path information of the book materials. The library indoor navigation service system using smart phones and mobile internet will bring great convenience to users and has important application value.
Comparison of indoor navigation technology
Indoor positioning is a key technology in the library's indoor navigation service system. Although global positioning system (GPS)-based outdoor positioning applications are very common, GPS systems receive very weak signals inside buildings and therefore cannot be effectively used indoors. At present, more indoor positioning technologies are used, such as Bluetooth technology and Wi-Fi technology.
Bluetooth positioning technology performs positioning by measuring the intensity of the received signal, which is suitable for short-range and small-range positioning. The disadvantages are that the equipment is expensive and the stability is poor, and it is not suitable for complex indoor positioning; the Wi-Fi positioning technology calculates the distance from the user to the wireless hotspot by the ranging method. This positioning method is easily interfered by other signals, thereby affecting the positioning accuracy, and the energy consumption of the positioner is relatively high, which is not conducive to energy saving and environmental protection.
In recent years, visible light communication technology has developed rapidly. Compared with traditional communication technologies (such as Bluetooth and Wi-Fi), it has significant advantages such as low power consumption, high speed, and no electromagnetic interference [3-4]. Since indoors are a natural place for visible light communication, indoor positioning methods based on visible light communication have received extensive attention. Indoor positioning using visible light communication technology has the following advantages:
(1) Low energy consumption. One of the components of the visible light communication system is an LED lamp that transmits signals using the principle of on-off illumination. The LED lamp is a new generation of green lighting equipment, which has the advantages of low energy consumption, long service life, small size and environmental protection;
(2) High positioning accuracy. Since the LED lamps are distributed throughout the room, the number of LED lamps that can be used for positioning is large each time, so the positioning accuracy is high;
(3) Widely used indoor positioning technology. The indoor positioning technology based on visible light communication has low cost, simple implementation and no electromagnetic interference, and can be applied to complex indoor environments and densely populated areas.
Based on the above advantages, the indoor communication technology of visible light communication will become the hot spot of the next research and application. On May 21, 2015, a flagship store in Carrefour France used visible light communication to implement supermarket indoor navigation services. Positioning services with less than 1 meter accuracy are achieved by arranging approximately 800 LED lights in the Carrefour supermarket.
Significance of research
Digital libraries are constantly moving forward. In the road of exploring future development, one thing is certain: no matter how advanced information resources are, electronic resources can never completely replace paper resources, and traditional services of libraries cannot be completely digital services. Replaced. After all, the user's sense of touch on the paper resources, the visual, the sound signals generated by the access and the realism carried can stimulate their perception, which are not possible with electronic resources. Therefore, indoor positioning technology based on visible light communication has a wide application space.
This paper will propose a library indoor navigation service system based on visible light communication and a specific positioning method. This kind of attempt to combine indoor positioning navigation and library services is the first in the field of graphics. It applies the new technology of network communication to practical work, fits the development direction of digital library, and can improve user experience. quality. This innovative approach and initiatives can improve productivity and give users a new way to experience. Therefore, the research on library indoor navigation service based on visible light communication has important practical significance.
Library indoor navigation service flow based on visible light communication
The flow of library indoor navigation service based on visible light communication proposed in this paper is shown in Figure 1. The entire process requires the following equipment:
(1) LED lights. LED lights are lighting fixtures installed in known locations in the library. Each LED light uses a small integrated circuit that can be turned on and off to give it a unique flash of light that corresponds to unique coded information. The flashing light from the LED light is greater than 120 Hz, so the human eye cannot see the flicker, but the mobile phone camera uses a rolling shutter to capture this flicker. The light emitted by the LED light corresponds to unique encoded information and corresponds to unique location information. A correspondence table of the encoded information and the location information is stored in the navigation server of the library.
(2) User handheld devices. After the user inputs the target book resource in the handheld device (such as a mobile phone), the handheld device camera is used to capture the LED light; then, the application on the handheld device decodes the LED to obtain the corresponding encoded information; then, the handheld device passes through the wireless network. Connect with the library navigation server, query the relationship table in the navigation server, and obtain the position of the LED light; finally, the application on the server uses the indoor positioning algorithm to obtain the location information of the handheld device, and returns it to the handheld device, combined with the handheld device. Map, display the required navigation information to the phone screen.
(3) Library navigation server. The library navigation server stores corresponding information, map information, and the like of the LED lamp code and location. The server's powerful computing power can assist the user's handheld device in performing related calculations. For example, the calculation of indoor positioning involves a relatively large amount of calculation, and this part of the calculation can be placed in the server, and the user's handheld device only needs to receive the final result.
The library indoor navigation service flow based on visible light communication includes the following steps:
Step 1: Enter the target resource. The user inputs the required target book data on the screen of the mobile phone, and obtains the specific location information of the target book resource by querying the map in the server as a navigation destination.
Step 2: Shoot. The user uses the handheld device to take pictures of the most recent LED lights, and the camera uses a rolling shutter to obtain the flashing information of these LED lights.
Step three: Decoding. Using image processing technology, the handheld device or server can decode the captured flicker information to obtain corresponding encoded information.
Step 4: Obtain the position information of the LED light. The server-side application searches the encoding location correspondence table on the server to obtain the location information of these LED lights.
Step 5: Indoor positioning. Based on the position information of several LED lights taken and their imaging information in the camera of the handheld device, the library navigation server uses the positioning method based on multiple LED lights to obtain the position of the handheld device. Shoot angle information as the starting point and direction of navigation.
Step 6: Navigate. The library navigation server uses the path finding algorithm to obtain navigation information from the starting point to the destination, which will be sent to the user's handheld device, combined with the acceleration sensor in the handheld device to provide navigation services for the user.
Conclusion
In the era of digital networking, digital libraries are constantly experimenting with the ever-changing changes and developments to meet the needs of readers. The library is transforming into an information space that can provide a variety of information services to enter a new field of information sharing. How to use the network communication technology to help readers to obtain the required book resources in all directions and quickly meet their basic service needs is a basic and important task.
The library should use modern information technology to continuously improve and develop the navigation service system, take resources and information as the object, and use innovative service means as a bridge to build a complete and efficient information service mechanism. With the advent of the mobile Internet era, library information technology has entered a new stage, from resource-oriented development to user-oriented.
The paper proposes to realize the indoor navigation of the library by means of the current new visible light communication technology, which can help the reader to quickly and efficiently obtain the required book resources, and improve the efficiency of searching for books and the quality of service. This is the first attempt to combine visible light communication technology with traditional library services to better serve readers and improve the user experience in the library. The new design ideas presented in this paper provide a valuable reference for the next research direction of the library.
Air circulator and turbo fan moves the air in a room by circulating air . The turbo fan only flows the air in one direction. The Air circulators are best used in clean and dry commercial applications – they are portable and easily positioned wherever is needed.
For an instant cooling effect, air circulators is the optimal choice, it can be portable and wall mounted.
Air Circulator and turbo fan is working by keeping the air in a room moving, so the Air Circulator Fan can be use Spring, Summer, Fall and Winter. Sepcial for Summer and Winter, using with air condition.
Welcome to OEM, thank you
Table Fan,Mini Table Fan,Rechargeable Table Fan,Best Table Fan
Fenry manufacturing Co., Ltd , https://www.cnfenry.com