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Research on fault detection method for heat pump air conditioning system under cold weather 被引量:6
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作者 Liangliang Sun Jianghua Wu +1 位作者 Haiqi Jia Xuebin Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第12期1812-1819,共8页
Building energy consumption accounts for nearly 40% of global energy consumption, HVAC (Heating, Ventilating, and Air Conditioning) systems are the major building energy consumers, and as one type of HVAC systems, t... Building energy consumption accounts for nearly 40% of global energy consumption, HVAC (Heating, Ventilating, and Air Conditioning) systems are the major building energy consumers, and as one type of HVAC systems, the heat pump air conditioning system, which is more energy-efficient compared to the traditional air conditioning system, is being more widely used to save energy. However, in northern China, extreme climatic conditions increase the cooling and heating load of the heat pump air conditioning system and accelerate the aging of the equipment, and the sensor may detect drifted parameters owing to climate change. This non-linear drifted parameter increases the false alarm rate of the fault detection and the need for unnecessary troubleshooting. In order to overcome the impact of the device aging and the drifted parameter, a Kalman filter and SPC (statistical process control) fault detection method are introduced in this paper. In this method, the model parameter and its standard variance can he estimated by Kalman filter based on the gray model and the real-time data of the air conditioning system. Further, by using SPC to construct the dynamic control limits, false alarm rate is reduced. And this paper mainly focuses on the cold machine failure in the component failure and its soft fault detection. This approach has been tested on a simulation model of the "Sino-German Energy Conservation Demonstration Center" building heat pump air-conditioning system in Shenyang, China, and the results show that the Kalman filter and SPC fault detection method is simple and highly efficient with a low false alarm rate, and it can deal with the difficulties caused by the extreme environment and the non-linear influence of the parameters, and what's more, it provides a good foundation for dynamic fault diagnosis and fault prediction analysis. 展开更多
关键词 Fault detection Cold machine Kalman filter statistical process control Dynamic control
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VOICE ACTIVITY DETECTION UNDER RAYLEIGH DISTRIBUTION 被引量:1
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作者 Li Yu Chen Jianming Tan Hongzhou 《Journal of Electronics(China)》 2009年第4期552-556,共5页
This paper presents an improved Voice Activity Detection (VAD) algorithm which uses the Signal-to-Noise Ratio (SNR) measure. We assume that noise Power Spectral Density (PSD) in each spectral bin follows a Rayle... This paper presents an improved Voice Activity Detection (VAD) algorithm which uses the Signal-to-Noise Ratio (SNR) measure. We assume that noise Power Spectral Density (PSD) in each spectral bin follows a Rayleigh distribution. Rayleigh distributions with its asymmetric tail characteristics give a better description of the noise PSD distribution than Gaussian distribution. Under this asstlmption, a new threshold updating expression is derived. Since the analytical integral of the false alarm probability, the threshold updating expression can be represented without the inverse complementary error function and low computational complexity is achieved in our system. Experimental results show that the proposed VAD outperforms or at least is comparable with the VAD scheme presented by Davis under several noise environments and has a lower computational complexity. 展开更多
关键词 statistical Voice Activity detection (VAD) Threshold update Rayleigh distribution Computational complexity
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SPREAD SPECTRUM WATERMARK DETECTION IN DRT-DOMAIN
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作者 Xing Guihua Yu Shenglin 《Journal of Electronics(China)》 2007年第6期782-786,共5页
The traditional correlation-based detector is optimal only for Gaussian data, but the Laplacian Probability Density Function (PDF) is more appropriate to model the coefficients in the Discrete Ridgelet Transform (DRT)... The traditional correlation-based detector is optimal only for Gaussian data, but the Laplacian Probability Density Function (PDF) is more appropriate to model the coefficients in the Discrete Ridgelet Transform (DRT) domain. An additive maximum-likelihood detector based on the Laplacian PDF is analyzed and the theoretical result of its performance is given. The experiments show that the error of the Laplacian model for the DRT coefficients of many images is smaller than that of the Gaussian model. The experiments also prove that the Laplacian detector is superior to the tradi- tional correlation-based detector. 展开更多
关键词 Ridgelet transform Digital watermarking Laplacian model statistical detection
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Low complexity method for spreading sequence estimation of DSSS signal in non-cooperative communication systems 被引量:10
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作者 Chang Liang Wang Fuping Wang Zanji 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第1期41-49,共9页
It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detec... It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics are proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity. 展开更多
关键词 direct sequence spread spectrum detection statistic low complexity.
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A STATISTICAL ANALYSIS OF SODAR DATA DETECTED IN YANSHAN MOUNTAIN AREA,BEIJING
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作者 吕乃平 周明煜 +1 位作者 苏立荣 陈炎涓 《Acta meteorologica Sinica》 SCIE 1989年第5期645-652,共8页
According to the characteristics of sodar echo,a classified method for temperature stratification is given. By using sodar data observed in Yanshan Mountain area in Beijing,the statistical characteristics for the heig... According to the characteristics of sodar echo,a classified method for temperature stratification is given. By using sodar data observed in Yanshan Mountain area in Beijing,the statistical characteristics for the height of inversion layer,thermal plume,and the depth of mixed layer are compared.Finally,the appearance frequency for stable,unstable and neutral stratification is analyzed. 展开更多
关键词 A statisticAL ANALYSIS OF SODAR DATA DETECTED IN YANSHAN MOUNTAIN AREA BEIJING Mean
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