The phase difference method (PDM) is presented for the direction of arrival (DOA) estimation of the narrowband source. It estimates the DOA by measuring the reciprocal of the phase range of the sensor output spectra a...The phase difference method (PDM) is presented for the direction of arrival (DOA) estimation of the narrowband source. It estimates the DOA by measuring the reciprocal of the phase range of the sensor output spectra at the interest frequency bin. The peak width and variance of the PDM are presented. The PDM can distinguish closely spaced sources with different and unknown center frequencies as long as they are separated with at least one frequency bin. The simulation results show that the PDM has a better resolution than that of the conventional beamforming.展开更多
In order to study the time-frequency characteristics of blasting vibration signals, measured in milliseconds, we carried out site blasting vibration tests at an open pit of the Jinduicheng Mine. Based on recorded fiel...In order to study the time-frequency characteristics of blasting vibration signals, measured in milliseconds, we carried out site blasting vibration tests at an open pit of the Jinduicheng Mine. Based on recorded field data and applying a combination of RSPWVD and wavelet, we analyzed the time-fre- quency characteristics of recorded field data, summarized the time-frequency characteristics of blasting vibration signals in different frequency bands and present detailed information of blasting vibration sig- nals in milliseconds of high time-frequency resolutions. Because RSPWVD can be seen as of definite physical significance to signal energy distribution in time and frequency domains, we studied the energy distribution of blasting vibration signals for various milliseconds intervals from a perspective of energy distribution. The results indicate that the effect of milliseconds intervals on time-frequency characteris- tics of blasting vibration signals is significant; the length of delay time directly affects the energy distri- bution of blasting vibration signals as well as the duration of energy in ffeauencv bands.展开更多
Physical-layer network coding(PNC) promises substantial theoretical gain to achieve the maximum system throughput in cooperative relay transmission. However, with the increasing global warming, how to reduce power con...Physical-layer network coding(PNC) promises substantial theoretical gain to achieve the maximum system throughput in cooperative relay transmission. However, with the increasing global warming, how to reduce power consumption while satisfy system throughput requirement is becoming a vital issue. In this paper, we investigate energy-efficiency resource allocation(RA) based on PNC with amplify-and-forward(AF) protocol in orthogonal frequency division multiple(OFDM) bidirectional transmission. To minimize the overall transmit power consumption with required system throughput requirement, we consider joint subcarriers and power allocation and formulate the objective task into a constrained optimization problem where the best relay node is selected to minimize total transmit power. The closed form optimization power allocation solutions are acquired by analytical derivation. Based on derivation, we propose a novel optimal energy-efficient power allocation(OE-PA). Numerical results are given to evaluate the performance of the derived scheme as compared to other schemes and show that our scheme has signifi cant improvement to energy saving.展开更多
Compared to a scalar pressure sensor, a vector sensor can provide a higher signal-to-noise ratio （SNR） signal and more detailed intbrmation on the sound field. Study on vector sensors and their applications have bec...Compared to a scalar pressure sensor, a vector sensor can provide a higher signal-to-noise ratio （SNR） signal and more detailed intbrmation on the sound field. Study on vector sensors and their applications have become a hot topic. Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology. This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship, and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform. From theory analysis and numerical simulation, the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but, being quantitatively different, provides additional information on the waveguide, especially through the vertical component. For the range-frequency representation, physical quantities that can better exhibit the interference characteristics of the wavegaide are the products of pressure and particle velocity and of the pressure and pressure gradient. An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly. The representation of the vector impulse response was discussed according to two different measurement systems, also known as particle velocity and pressure gradient. The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.展开更多
基金the National Science Foundation under Grant No. 60672136the the Doctorate Foundation of Northwestern Polytechnical University under Grant No.CX200803
文摘The phase difference method (PDM) is presented for the direction of arrival (DOA) estimation of the narrowband source. It estimates the DOA by measuring the reciprocal of the phase range of the sensor output spectra at the interest frequency bin. The peak width and variance of the PDM are presented. The PDM can distinguish closely spaced sources with different and unknown center frequencies as long as they are separated with at least one frequency bin. The simulation results show that the PDM has a better resolution than that of the conventional beamforming.
基金supported by the Fundamental Research Funds for Central Universities (No.2010-Ia-060)
文摘In order to study the time-frequency characteristics of blasting vibration signals, measured in milliseconds, we carried out site blasting vibration tests at an open pit of the Jinduicheng Mine. Based on recorded field data and applying a combination of RSPWVD and wavelet, we analyzed the time-fre- quency characteristics of recorded field data, summarized the time-frequency characteristics of blasting vibration signals in different frequency bands and present detailed information of blasting vibration sig- nals in milliseconds of high time-frequency resolutions. Because RSPWVD can be seen as of definite physical significance to signal energy distribution in time and frequency domains, we studied the energy distribution of blasting vibration signals for various milliseconds intervals from a perspective of energy distribution. The results indicate that the effect of milliseconds intervals on time-frequency characteris- tics of blasting vibration signals is significant; the length of delay time directly affects the energy distri- bution of blasting vibration signals as well as the duration of energy in ffeauencv bands.
基金supported by the Science Instrument Special Funds of the National Natural Science Foundation of China under Grant No.61027003the National High Technology Research and Development Program of China under Grant No.2012AA01A50604
文摘Physical-layer network coding(PNC) promises substantial theoretical gain to achieve the maximum system throughput in cooperative relay transmission. However, with the increasing global warming, how to reduce power consumption while satisfy system throughput requirement is becoming a vital issue. In this paper, we investigate energy-efficiency resource allocation(RA) based on PNC with amplify-and-forward(AF) protocol in orthogonal frequency division multiple(OFDM) bidirectional transmission. To minimize the overall transmit power consumption with required system throughput requirement, we consider joint subcarriers and power allocation and formulate the objective task into a constrained optimization problem where the best relay node is selected to minimize total transmit power. The closed form optimization power allocation solutions are acquired by analytical derivation. Based on derivation, we propose a novel optimal energy-efficient power allocation(OE-PA). Numerical results are given to evaluate the performance of the derived scheme as compared to other schemes and show that our scheme has signifi cant improvement to energy saving.
基金Supported by Office of Naval Research grant N00014-07-1-1069the National Nature Science Foundation of China grant 50979019the Belgian National Fund for Scientific Research (F.R.S. - FNRS)
文摘Compared to a scalar pressure sensor, a vector sensor can provide a higher signal-to-noise ratio （SNR） signal and more detailed intbrmation on the sound field. Study on vector sensors and their applications have become a hot topic. Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology. This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship, and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform. From theory analysis and numerical simulation, the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but, being quantitatively different, provides additional information on the waveguide, especially through the vertical component. For the range-frequency representation, physical quantities that can better exhibit the interference characteristics of the wavegaide are the products of pressure and particle velocity and of the pressure and pressure gradient. An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly. The representation of the vector impulse response was discussed according to two different measurement systems, also known as particle velocity and pressure gradient. The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.
