Recognition Technology for Four Arithmetic Operations

Numeral recognition is an important research direction in field of pattern recognition, and it has broad application prospects. Aiming at four arithmetic operations of general printed formats, this article adopts a multiple hybrid recognition method and is applied to automatically calculating. This method mainly uses BP neural network and template matching method to distinguish the numerals and operators, in order to increase the operation speed and recognition accuracy. Sample images of four arithmetic operations are extracted from printed books, and they are used for testing the performance of proposed recognition method. The experiments show that the method provides correct recognition rate of 96% and correct calculation rate of 89%

PrivSyn: Differentially Private Data Synthesis

In differential privacy (DP), a challenging problem is to generate synthetic datasets that efficiently capture the useful information in the private data. The synthetic dataset enables any task to be done without privacy concern and modification to existing algorithms. In this paper, we present PrivSyn, the first automatic synthetic data generation method that can handle general tabular datasets (with 100 attributes and domain size $>2^{500}$). PrivSyn is composed of a new method to automatically and privately identify correlations in the data, and a novel method to generate sample data from a dense graphic model. We extensively evaluate different methods on multiple datasets to demonstrate the performance of our method

Analytical modeling and calculation of core grounding current in converter transformer

In recent years, the calculation of the core grounding current of the converter transformer is difficult, low precision, and time-consuming, especially when the core is grounded by multiple points. This makes it difficult to analyze the core grounding current. To improve the accuracy of the calculation and reduce the complexity of the calculation, this paper carries out analytical calculation, simulation analysis, and experimental research on the grounding current of the converter transformer core. Firstly, a calculation method of core grounding current considering the winding connection of the converter transformer is proposed. In the implementation process, the converter transformer circuit model is established and the influence of saturation characteristics is considered, and the core grounding current is calculated and analyzed. Secondly, the grounding current of the converter transformer core is calculated by the finite element method (FEM). Finally, the proposed scheme is verified by experiments. The results show that the analytical method is close to the FEM and the experimental method, which indicates that the analytical method proposed can meet the accuracy requirements of engineering in this paper, and provides a new scheme for fast and accurate calculation of the grounding current of the converter transformer core

Research on gas production law of free gas in oil-immersed power transformer under discharge fault of different severity

Dissolved gas analysis (DGA) is a common technology used in the on-site maintenance of oil-immersed power transformers in the power industry at present. However, when the content of dissolved gas in the oil reaches the attention value DGA method can effectively diagnose the operating state of the transformer. Due to the lack of gas production data of free gas which was detected when the faults occur, DGA method cannot timely diagnose the transformer status. To solve the above problem, an experimental platform is built for studying the free gas generation law in oil-immersed transformers under discharge faults, and the characteristic free gas information under discharge fault of transformer is obtained through the experiment. It is found that the existing DGA method cannot accurately analyze the types and severity of sudden serious insulation faults. When high-energy partial discharge fault occurred in the equipment, CO, CO2, CH4, and H2 will be collected in large quantities on the oil surface. These four gases can be used as the basis for characterizing high-energy partial discharge faults. When spark discharge occurred in the equipment, C2H6, C2H4, and C2H2 also be collected on the oil surface which can be used as a diagnostic basis for spark discharge. Moreover, it is found that the existing three-ratio method cannot be used for accurate analysis of oil free characteristic gas, so it is necessary to explore new diagnostic methods. The aim of this study is to explore the pattern of free gas production law by experiments when discharge faults occur and to provide data for a new diagnostic method

Energy-saving Routing Algorithm Based on Cluster in WSN

This paper takes the improved threshold formula and cluster radios formulas to choose cluster-heads by considering energy-saving, based on typical clustering routing protocol and optimal cluster-head selection formula. In the forming stage of cluster, the proportionality principle is used to make the distribution of cluster even more reasonable and during the stable stage of cluster, the member nodes in cluster use TDMA to communicate with the cluster-head node, and cluster-head nodes communicate with base station BS via multi-hop interrupt communication manner. Then it proposed the realization of target tracking based on the energy- saving routing algorithm. Finally, it can be seen in the simulation results that on the behalf of the network lifetime and average energy consumption, energy-saving routing algorithm is more reasonable. DOI: http://dx.doi.org/10.11591/telkomnika.v11i2.203

Remote Monitoring System Based on GPRS - A Case Study for Water Withdrawal

In order to realize supervision of water withdrawal, it is necessary to establish a modern monitoring system. This study focuses on the design of a remote monitoring terminal system that is operating in a south province in China. This terminal system adopts GPRS mode to establish communication with monitoring center. Detailed hardware design is provided, as well as its software functions. This terminal device finishes the basic function of water quantity collection. At the meantime, remote upgrade function and picture collection function are proposed in order to perfect the overall function of the system. Kinds of tests were conducted to verify its performances and functionalities. We conclude that the proposed remote monitoring terminal might become a useful tool for supervision of water withdrawal in the dispersed areas

Remote Monitoring System Based on GPRS - A Case Study for Water Withdrawal

In order to realize supervision of water withdrawal, it is necessary to establish a modern monitoring system. This study focuses on the design of a remote monitoring terminal system that is operating in a south province in China. This terminal system adopts GPRS mode to establish communication with monitoring center. Detailed hardware design is provided, as well as its software functions. This terminal device finishes the basic function of water quantity collection. At the meantime, remote upgrade function and picture collection function are proposed in order to perfect the overall function of the system. Kinds of tests were conducted to verify its performances and functionalities. We conclude that the proposed remote monitoring terminal might become a useful tool for supervision of water withdrawal in the dispersed areas

Mathematical modeling and experimental research on grounding current calculation of converter transformer core

When the converter transformer core is grounded at multi-points, a fault loop will be formed and a circulation will be generated, leading to local overheating of the magnetic core and decomposition of insulating oil. Therefore, the converter transformer core will be single point grounded. As a rare internal lead of converter transformer, the ground current on the core ground lead can often reflect the running state of converter transformer. In this paper, theoretical analysis, modeling simulation and experimental research are carried out on the ground current of converter transformer at one point. Firstly, according to the structure characteristics of converter transformer, the analytical modeling of ground current is carried out. Secondly, based on the structure characteristics of oil paper insulation, the equivalent capacitance of converter transformer is calculated. Then, the analytical and finite element simulation model of converter transformer is established, and the ground current of converter transformer is calculated. Finally, the correctness of the proposed scheme is verified by measuring the grounding current of converter transformer core

A π-Phase-Shifted Fiber Bragg Grating Partial Discharge Sensor toward Power Transformers

Partial discharge (PD) ultrasonic detection is an early sign of the insolation defects of power transformers. The early diagnosis of PD requires the high sensitivity and reliability of ultrasonic sensing systems. For this purpose, a reformative PD ultrasonic sensing system based on phase-shifted FBG (PS-FBG) was demonstrated. By using PS-FBG as the ultrasonic sensing unit, the ultrasonic sensing system improved the response to the ultrasonic signal and overcame the electromagnetic noise. To compensate for the influence of temperature change on the ultrasonic sensing system, an automatic wavelength scanning demodulating method was carried out. The wavelength spanning strategy was optimized based on the principle of cross-correlation, in order to quicken the spanning. A PD detection test in the transformer oil was conducted, and the result shows that PS-FBG was 17.5 times more sensitive than PZT. Because of the better ultrasonic response, the proposed system was able to achieve the early diagnosis of insolation faults in a power transformer