The system uses ASP. net technology to realize user registration, user personal management, goods inquiry, commodity information upload, seller bidding, one-price purchase, personal credibility measurement, administrator maintenance and management and other functions.
The system meets the requirements of beautiful interface, good guidance and user-friendly operation. It can greatly reduce the difficulty of operation and save time and energy for users in the process of online auction and purchase. With the development of network technology, e-commerce has developed rapidly and become one of the fastest growing, most widely applied and constantly changing fields in the world. It greatly improves the convenience and flexibility of the market, and changes people’s life and work mode. With the vigorous development of e-commerce, online auction has become a noticeable new form of commodity trading. It makes the noble form of commodity exchange that only a few people can participate in in in the past become a civilian form of transaction that every netizen can join. Online auction can not be limited by time and space and can face customers from the whole country or even the world. Merchandise sellers only need to upload the information of the goods to be sold, and then wait for the buyer to bid, which greatly saves human, financial and material resources.
Therefore, the online auction platform becomes very important for people’s daily life. Online auction system is a management system about commodity sale and commodity auction.
This system provides a trading platform for price negotiation through the Internet. By publishing the information of the goods or services to be tendered on the website, it will be sold to the highest or lowest bidder through competitive bidding. Its essence is to take competitive price as the core, so as to establish a mechanism of communication and interaction between producers and consumers, and jointly determine prices and quantities. This system adopts ASP technology, mainly including the establishment and maintenance of background database and the development of front-end application program. It realizes many functions, such as user registration, user personal information management, auction items query, commodity information upload, buyer bidding, one-time price purchase, personal credibility measurement, administrator maintenance management, etc. This system includes user system module and administrator system module, in which user system module includes: commodity purchase, commodity sale, sign message, complaint management, commodity inquiry, information maintenance and other functions. The administrator system module includes user information management, commodity management, complaint management, property rights information maintenance and other functions. The function modules of the online auction system are shown in Figure 1. This system uses SQL Server 2000 database, database name Auction. Column Information Table: Store column information. Description: User information table is mainly used for user login, users have rights (administrators, ordinary members) through user name and password verification; administrators can manage background data, ordinary users enter the foreground to browse commodity information, the first entry into the system need to register before they can login [3]. The system includes two modules: user management module and administrator management module. User management module is mainly a functional module for users, including user registration, user login, purchase of goods, sale of goods, sign-up messages, user complaints and so on.
Administrator module is a functional module for administrators, including membership management, product classification management, complaint management, product management and so on. After entering the registration page, the user must register first, and then enter the commodity browsing page with the registered user name. By choosing, the user can enter the commodity he wants in the search function bar to search, select the commodity he wants to buy, and browse the detailed information of the commodity. One-price commodity: The system retrieves the user’s account balance from the database and prompts the user if it is not enough to purchase the commodity. Otherwise, thermostatic element the money used to purchase the goods will be deducted from the balance of the account, and then the goods will be deposited in the information of the goods purchased by the users. // In order to deal with the problem that HTTPS protocol converts links into links with port number 444 by default when converting complex links. The software design adopts modular structure, including system initialization, system parameter setting and storage, switch state detection, A/D acquisition, frequency measurement, output drive, display and alarm, etc.
After the device is powered on, the system is initialized (some variables and protections are initially processed), the communication connection is established with the remote monitor through CAN bus, then the AD sampling is carried out circularly, and the asynchronous sampling is adopted (all channels are not sampled at the same time, but sequentially, the multi-channel switch is used for switching). The AD sampling data are generally stored in the circular queue at 32 points per week for convenience of Fourier transform. The calculation of inner algorithm includes setting timer, sampling two power supply, protecting CT sampling protection current Iap, Ibp and Icp, measuring CT sampling input current ITL1 and ITL2, using Fourier algorithm to calculate AC quantity (as shown in formula 1), judging whether there is phase-gap interruption, counting the number of phase-gap interruption, sampling out voltage Uab2, Ubc2 and in-line voltage U1 and Uabl, detecting voltage, judging whether there is phase-gap interruption or not. If there is over-voltage, under-voltage, voltage-loss, cumulative sampling times, if the cyclic sampling time does not arrive, then the data sampling will be re-conducted; if the cyclic sampling time arrives, if the phase-absence judgment period does not arrive, the defect will be judged according to the number of interruptions. If the phase-absence judgment period arrives, the position of the counseling switch will be detected and the current power supply will be displayed, and the data communication with the monitoring terminal will be completed (Formula 2 is used to calculate the electricity).
Voltage or current value), and then judge that the current BZT is manual or automatic switching, if automatic switching, only when one end of the power supply is normal and the other end of the power supply is out of voltage, the standby self-switching will switch to the normal end; if automatic switching, only when one end of the power supply is normal and the other end of the power supply is out of voltage, the standby self-switching will switch to the normal end.
Among them, lambda: each harmonic (including fundamental) 0, 1, 2,…
A lambda: sinusoidal term of each harmonic (including fundamental wave), B lambda: cosine term of each harmonic (including fundamental wave), N: sampling point of a power frequency cycle, sampling value of X (k): x (t) at TK time, In is the current rating, Un is the voltage rating, DI is the current binary value of transmission, DU is the voltage binary value of transmission. In software processing, trapezoidal method is used to calculate the integral value.
In Figure 3, 1DL, 2DL and 3DL are switch positions, Uab2 and Ubc2 are 2 For pressure judgment, Ix1 and Ix2 are used to block the misoperation caused by three-phase PT disconnection. The dual-power backup self-switching controller is intellectualized, digitized and networked.
Through signal acquisition and processing circuit, it can real-time detect the status of common and standby power supply. It can detect the defects, overvoltage, undervoltage and voltage loss of the dual power supply, and can reliably switch between the backup power supply. In hardware, it adopts the technology of DSP microprocessor, which has fast operation speed and good performance. The design cycle is shortened by using modular software design method. Software filtering and watchdog technology are used in the design to enhance the reliability of the system. Practical operation shows that the BZT has perfect function and reliable operation, and can monitor and display the working state of power supply and remote communication control.