In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are di...In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are divided by unknown intervals because of dynamic moving.Three parameters are taken to indicate the steering vector,namely,the direction of arrivals(DOAs)of target users,the intervals of UAVs,and the orientation angles of UAVs.The orientation angles are first estimated with an auxiliary user and the DOAs are obtained through a search free rooting method,despite the intervals among the UAVs.Afterwards,the intervals among UAVs can also be calculated via exhaustive when the number of target users are no less than three.We further develop a low-complex method to reduce the computational complexity during subarray-interval estimation.The deterministic Cramér-Rao bound(CRB)of the DOA,orientation angle and subarray-interval can be inferred in a closed form.Eventually,numerical instances are cited to verify the research results.展开更多
A joint Doppler shift and channel estimation method for the millimeter-wave communication system of an unmanned aerial vehicle(UAV) equipped with a large-scale uniform linear antenna(ULA) array has been proposed. Sinc...A joint Doppler shift and channel estimation method for the millimeter-wave communication system of an unmanned aerial vehicle(UAV) equipped with a large-scale uniform linear antenna(ULA) array has been proposed. Since Doppler shift induces intercarrier interference, the parameters of the channel paths have been decomposed into the Doppler shift and the channel information. In order to obtain the Doppler shift, a new estimation algorithm based on a combination of discrete Fourier transform and phase rotation has been proposed, which can determine the appropriate number of antennas. In addition to estimating the channel information, a low-complexity joint Doppler shift and channel estimation method has been designed that can quickly obtain accurate estimates. Furthermore, the achievable sum rate, the theoretical bounds of the mean squared errors, and the Cram?er-Rao lower bounds of the estimation method have been derived. The analysis and simulation results prove that the performance of the proposed approach is close to the theoretical inference.展开更多
Endometriosis,a heterogeneous,inflammatory,and estrogen-dependent gynecological disease defined by the presence and growth of endometrial tissues outside the lining of the uterus,affects approximately 5-10%of reproduc...Endometriosis,a heterogeneous,inflammatory,and estrogen-dependent gynecological disease defined by the presence and growth of endometrial tissues outside the lining of the uterus,affects approximately 5-10%of reproductive-age women,causing chronic pelvic pain and reduced fertility.Although the etiology of endometriosis is still elusive,emerging evidence supports the idea that immune dysregulation can promote the survival and growth of retrograde endometrial debris.Peritoneal macrophages and natural killer(NK)cells exhibit deficient cytotoxicity in the endometriotic microenvironment,leading to inefficient eradication of refluxed endometrial fragments.In addition,the imbalance of T-cell subtypes results in aberrant cytokine production and chronic inflammation,which contribute to endometriosis development.Although it remains uncertain whether immune dysregulation represents an initial cause or merely a secondary enhancer of endometriosis,therapies targeting altered immune pathways exhibit satisfactory effects in preventing disease onset and progression.Here,we summarize the phenotypic and functional alterations of immune cells in the endometriotic microenvironment,focusing on their interactions with microbiota and endocrine and nervous systems,and how these interactions contribute to the etiology and symptomology of endometriosis.展开更多
This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing d...This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 ℃/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.展开更多
We propose a novel modified frequency-shifted interferometer, where a Mach–Zehnder interferometer is added in order to obtain wavelength information. We use the Hilbert transform to extract the wavelength information...We propose a novel modified frequency-shifted interferometer, where a Mach–Zehnder interferometer is added in order to obtain wavelength information. We use the Hilbert transform to extract the wavelength information from the phase of the interference pattern and construct the relationship between phase and wavelength. The laser wavelength measurement experiment is used to verify the compound interferometer. Experimental results demonstrated that our method could obtain the wavelength from the phase, which is of great significance for demodulation of the fiber Bragg grating based on a frequency-shifted interferometer.展开更多
基金supported by National Natural Science Foundation of China(No.62101601)。
文摘In this paper,DOA and subarray-interval estimation are considered and applied to arbitrarily distributed unmanned aerial vehicle(UAV)swarm system,in which multiple small UAVs containing uniform linear array(ULA)are divided by unknown intervals because of dynamic moving.Three parameters are taken to indicate the steering vector,namely,the direction of arrivals(DOAs)of target users,the intervals of UAVs,and the orientation angles of UAVs.The orientation angles are first estimated with an auxiliary user and the DOAs are obtained through a search free rooting method,despite the intervals among the UAVs.Afterwards,the intervals among UAVs can also be calculated via exhaustive when the number of target users are no less than three.We further develop a low-complex method to reduce the computational complexity during subarray-interval estimation.The deterministic Cramér-Rao bound(CRB)of the DOA,orientation angle and subarray-interval can be inferred in a closed form.Eventually,numerical instances are cited to verify the research results.
基金supported by National Natural Science Foundation of China (No. 62101601, No.61971445)。
文摘A joint Doppler shift and channel estimation method for the millimeter-wave communication system of an unmanned aerial vehicle(UAV) equipped with a large-scale uniform linear antenna(ULA) array has been proposed. Since Doppler shift induces intercarrier interference, the parameters of the channel paths have been decomposed into the Doppler shift and the channel information. In order to obtain the Doppler shift, a new estimation algorithm based on a combination of discrete Fourier transform and phase rotation has been proposed, which can determine the appropriate number of antennas. In addition to estimating the channel information, a low-complexity joint Doppler shift and channel estimation method has been designed that can quickly obtain accurate estimates. Furthermore, the achievable sum rate, the theoretical bounds of the mean squared errors, and the Cram?er-Rao lower bounds of the estimation method have been derived. The analysis and simulation results prove that the performance of the proposed approach is close to the theoretical inference.
基金supported by grants from the National Natural Science Foundation of China(Nos.82273255,81822034,81821002,and 81773119)National Key Research and Development Program of China(Nos.2022YFA1106600,2017YFA0106800,and 2018YFA0109200)+1 种基金Sichuan Science-Technology Project(Nos.22ZYZYTS0070 and 2019YFH0144)Direct Scientific Research Grants from West China Second Hospital,Sichuan University(Nos.KS021 and K1907)
文摘Endometriosis,a heterogeneous,inflammatory,and estrogen-dependent gynecological disease defined by the presence and growth of endometrial tissues outside the lining of the uterus,affects approximately 5-10%of reproductive-age women,causing chronic pelvic pain and reduced fertility.Although the etiology of endometriosis is still elusive,emerging evidence supports the idea that immune dysregulation can promote the survival and growth of retrograde endometrial debris.Peritoneal macrophages and natural killer(NK)cells exhibit deficient cytotoxicity in the endometriotic microenvironment,leading to inefficient eradication of refluxed endometrial fragments.In addition,the imbalance of T-cell subtypes results in aberrant cytokine production and chronic inflammation,which contribute to endometriosis development.Although it remains uncertain whether immune dysregulation represents an initial cause or merely a secondary enhancer of endometriosis,therapies targeting altered immune pathways exhibit satisfactory effects in preventing disease onset and progression.Here,we summarize the phenotypic and functional alterations of immune cells in the endometriotic microenvironment,focusing on their interactions with microbiota and endocrine and nervous systems,and how these interactions contribute to the etiology and symptomology of endometriosis.
基金This work was supported by the Chinese National Science Foundation under Grant 51275373 and the Chinese Fundamental Research Funds for the Central University under Grant 2012-IV -019.
文摘This paper presents the testing results of three types of fire detectors: electrical heat sensing cable, optical fiber Raman temperature sensing detector, and optical fiber Bragg grating (FBG) temperature sensing detector, in two simulated fire scenes in a cable tunnel. In the small-scale fire with limited thermal radiation and no flame, the fire alarm only comes from the heat sensors which directly contact with the heat source. In the large-scale fire with about 5 ℃/min temperature rising speed within a 3-m span, the fire alarm response time of the fiber Raman sensor and FBG sensors was about 30 seconds. The test results can be further used for formulating regulation for early fire detection in cable tunnels.
基金supported by the National Natural Science Foundation of China (NSFC)(Nos. 61775173 and 61975157)
文摘We propose a novel modified frequency-shifted interferometer, where a Mach–Zehnder interferometer is added in order to obtain wavelength information. We use the Hilbert transform to extract the wavelength information from the phase of the interference pattern and construct the relationship between phase and wavelength. The laser wavelength measurement experiment is used to verify the compound interferometer. Experimental results demonstrated that our method could obtain the wavelength from the phase, which is of great significance for demodulation of the fiber Bragg grating based on a frequency-shifted interferometer.