The Mandatory Energy Efficiency Standard for Distribution Transformer soon Publicized in China

Owning to the rapid economy development in China and sharp increase of energyconsumption in recent years, energy shortage is increasingly apparent and becoming an importantobstacle to the sustainable development of our economy. With the aim to relieve the problem ofenergy shortage, the State Development and Reform Commission places the great emphasis ofenergy-saving work on improving energy efficiency of industrial energy-consuming products inenergy-saving work. The General Administration of Quality Supervision, Inspection and Quarantine ofthe People's Republic of China (AQSIQ) has issued and implemented two energy efficiency standardsfor three-phase induction motors and displacement air compressor, and will soon issue another twoenergy efficiency standards for clean- water centrifugal pumps and ventilation fans. The transformeris a kind of electric equipment widely used in many industries in national economy, with featuresof great amount of use, long period of operation and tremendous potential of energy-saving. So, itis necessary to develop the standard of energy efficiency for distribution transformers.

Application of the catastrophe progression method in predicting coal and gas outburst

Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.

Analysis of pressure pulsation mechanism and dynamic characteristics of axial piston pump

The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.