On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground...On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground equipment were studied at different work conditions. The result indicates that the noise source intensity surpasses the noise limit requirement of 85 dBA completely. Nearly 70% noise sources exceed the noise limit of 90 dBA, and some are over 100 dBA. Noise attenua- tion in semi-free field environment on the ground is significantly different from underground far-field environment of noise source in coal mines. Noise of these regions, where staffs are long and highly concentrated, exceeds 85 dBA, the basic noise limit. The noise frequency-spectrum presents the wideband characteristics. Especially in the main frequency of the language communication 500, 1 000 and 2 000 Hz, the octave band of noise performs obviously.展开更多
As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in effic...As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.展开更多
With the development of mining industry,people have obtained profits from it,but they are facing environmental damages.In order to monitor these environmental changes,a spectral library is set up for the spectrum data...With the development of mining industry,people have obtained profits from it,but they are facing environmental damages.In order to monitor these environmental changes,a spectral library is set up for the spectrum data organization and management of mine typical objects.Most of the spectrum data come from the long-term field measuring in mining area and other spectral libraries.For the data quality control and error detection in the measuring data,an inner precision calculation method is presented and a series of interactive graphical controls are developed for the spectrum visualization and analysis.Through extracting and saving spectrum characters for the mine typical objects,realizs spectrum matching and classification for new measured spectrum samples are realized by using Euclidean distance,Aitchison distance,Pearson correlation coefficient and vector angular cosine methods.Based on the matching result,this work is able to gather dynamically physicochemical environment parameters from the library and gives an early warning for the mine environmental changes.展开更多
This paper focuses on improving the detection performance of spectrum sensing in cognitive radio(CR) networks under complicated electromagnetic environment. Some existing fast spectrum sensing algorithms cannot get sp...This paper focuses on improving the detection performance of spectrum sensing in cognitive radio(CR) networks under complicated electromagnetic environment. Some existing fast spectrum sensing algorithms cannot get specific features of the licensed users'(LUs') signal, thus they cannot be applied in this situation without knowing the power of noise. On the other hand some algorithms that yield specific features are too complicated. In this paper, an algorithm based on the cyclostationary feature detection and theory of Hilbert transformation is proposed. Comparing with the conventional cyclostationary feature detection algorithm, this approach is more flexible i.e. it can flexibly change the computational complexity according to current electromagnetic environment by changing its sampling times and the step size of cyclic frequency. Results of simulation indicate that this approach can flexibly detect the feature of received signal and provide satisfactory detection performance compared to existing approaches in low Signal-to-noise Ratio(SNR) situations.展开更多
基金Supported by the National Natural Science Foundation of China （50974061） the Natural Science Foundation of Hebei Province （E2009001420）
文摘On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines, Kailuan Group, noise radiation intensity, noise propagation properties and noise frequency-spectrum characteristics of underground equipment were studied at different work conditions. The result indicates that the noise source intensity surpasses the noise limit requirement of 85 dBA completely. Nearly 70% noise sources exceed the noise limit of 90 dBA, and some are over 100 dBA. Noise attenua- tion in semi-free field environment on the ground is significantly different from underground far-field environment of noise source in coal mines. Noise of these regions, where staffs are long and highly concentrated, exceeds 85 dBA, the basic noise limit. The noise frequency-spectrum presents the wideband characteristics. Especially in the main frequency of the language communication 500, 1 000 and 2 000 Hz, the octave band of noise performs obviously.
基金the Project of National Natural Science Foundation of China (Grant No. 61471395, No. 61301161, and No. 61501510)partly supported by Natural Science Foundation of Jiangsu Province (Grant No. BK20161125 and No. BK20150717)
文摘As the earliest invented and utilized communication approach, shortwave, known as high frequency(HF) communication now experience the deterioration of HF electromagnetic environment. Finding quality frequency in efficient manner becomes one of the key challenges in HF communication. Spectrum prediction infers the future spectrum status from history spectrum data by exploring the inherent correlations and regularities. The investigation of HF electromagnetic environment data reveals the correlations and predictability of HF frequency band in both time and frequency domain. To solve this problem, we develop a Spectrum Prediction-based Frequency Band Pre-selection(SP-FBP) for HF communications. The pre-selection of HF frequency band mainly incorporated in prediction of HF spectrum occupancy and prediction of HF usable frequency, which provide the frequency band ranking of spectrum occupancy and alternative frequency for spectrum sensing, respectively. Performance evaluation via real-world HF spectrum data shows that SP-FBP significantly improves the efficiency of finding quality frequency in HF communications.
基金Supported by the National Key Technology R&D Program of China(No.2012BAH27B04,2011BAC03B03)the National Natural Science Foundation of China(No.41471330)+1 种基金Research Fund for the Doctoral Program of Higher Education of China(20113718110001)SDUST Research Fund(2011KYTD103)
文摘With the development of mining industry,people have obtained profits from it,but they are facing environmental damages.In order to monitor these environmental changes,a spectral library is set up for the spectrum data organization and management of mine typical objects.Most of the spectrum data come from the long-term field measuring in mining area and other spectral libraries.For the data quality control and error detection in the measuring data,an inner precision calculation method is presented and a series of interactive graphical controls are developed for the spectrum visualization and analysis.Through extracting and saving spectrum characters for the mine typical objects,realizs spectrum matching and classification for new measured spectrum samples are realized by using Euclidean distance,Aitchison distance,Pearson correlation coefficient and vector angular cosine methods.Based on the matching result,this work is able to gather dynamically physicochemical environment parameters from the library and gives an early warning for the mine environmental changes.
基金sponsored by National Basic Research Program of China (973 Program, No. 2013CB329003)National Natural Science Foundation of China (No. 91438205)+1 种基金China Postdoctoral Science Foundation (No. 2011M500664)Open Research fund Program of Key Lab. for Spacecraft TT&C and Communication, Ministry of Education, China (No.CTTC-FX201305)
文摘This paper focuses on improving the detection performance of spectrum sensing in cognitive radio(CR) networks under complicated electromagnetic environment. Some existing fast spectrum sensing algorithms cannot get specific features of the licensed users'(LUs') signal, thus they cannot be applied in this situation without knowing the power of noise. On the other hand some algorithms that yield specific features are too complicated. In this paper, an algorithm based on the cyclostationary feature detection and theory of Hilbert transformation is proposed. Comparing with the conventional cyclostationary feature detection algorithm, this approach is more flexible i.e. it can flexibly change the computational complexity according to current electromagnetic environment by changing its sampling times and the step size of cyclic frequency. Results of simulation indicate that this approach can flexibly detect the feature of received signal and provide satisfactory detection performance compared to existing approaches in low Signal-to-noise Ratio(SNR) situations.
