For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consis...For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consisting of channel gainphase mismatch and position uncertainty, significantly degrade the performance of such systems. An iteration-free method is proposed to simultaneously estimate position and gain-phase errors.In our research, the steering vectors corresponding to a pair of Doppler bins within the same range bin are studied in terms of their rotational relationships. The method is based on the fact that the rotational matrix only depends on the position errors and the frequency spacing between the paired Doppler bins but is independent of gain-phase error. Upon combining the projection matrices corresponding to the paired Doppler bins, the position errors are directly obtained in terms of extracting the rotational matrix in a least squares framework. The proposed method, when used in conjunction with the self-calibration algorithm, performs stably as well as has less computational load, compared with the conventional methods. Simulations reveal that the proposed method behaves better than the conventional methods even when the signal-to-noise ratio（SNR） is low.展开更多
A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<...A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<sup>3+</sup>-doped BaWO<sub>4</sub> samples were studied. The results indicated that luminescent properties of BaWO<sub>4</sub>:Dy<sup>3+</sup> depended on the Dy<sup>3+</sup> concentration, and the inner energy could transfer from to Dy<sup>3+</sup>. The quality of the light was checked by estimating CIE parameters, and the results showed that BaWO<sub>4</sub>:Dy<sup>3+</sup> was a potential candidate as blue-green luminescent materials in white LED because of its excellent emission spectrum excited by UV light.展开更多
Dear Editor,Melanoma,squamous cell carcinoma(SCC),and basal cell carcinoma(BCC)are three major types of skin cancer.Among them,melanoma is the most severe form and accounts for~4%of all newly diagnosed cancers annuall...Dear Editor,Melanoma,squamous cell carcinoma(SCC),and basal cell carcinoma(BCC)are three major types of skin cancer.Among them,melanoma is the most severe form and accounts for~4%of all newly diagnosed cancers annually in the United States.It is estimated that approximately 9500 people are diagnosed with skin cancer every day,and more than 1 million Americans are living with melanoma.Melanoma treatment is still a major challenge in the clinic.Photodynamic therapy(PDT)is composed of targeted ablation and immune activation,is less invasive than other therapies and has been widely used in the treatment of various cancers.展开更多
基金supported by the Natural Science Basic Research Plan in Shaanxi Province of China(2015JM6278)the China Postdoctoral Science Foundation(2015M582586)the China Academy of Space Technology Innovation Fund
文摘For multi-channel synthetic aperture radar（SAR） systems, since the minimum antenna area constraint is eliminated,wide swath and high resolution SAR image can be achieved.However, the unavoidable array errors, consisting of channel gainphase mismatch and position uncertainty, significantly degrade the performance of such systems. An iteration-free method is proposed to simultaneously estimate position and gain-phase errors.In our research, the steering vectors corresponding to a pair of Doppler bins within the same range bin are studied in terms of their rotational relationships. The method is based on the fact that the rotational matrix only depends on the position errors and the frequency spacing between the paired Doppler bins but is independent of gain-phase error. Upon combining the projection matrices corresponding to the paired Doppler bins, the position errors are directly obtained in terms of extracting the rotational matrix in a least squares framework. The proposed method, when used in conjunction with the self-calibration algorithm, performs stably as well as has less computational load, compared with the conventional methods. Simulations reveal that the proposed method behaves better than the conventional methods even when the signal-to-noise ratio（SNR） is low.
文摘A series of barium-tungstate-based phosphors doped with different concentrations of Dy<sup>3+</sup> were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy<sup>3+</sup>-doped BaWO<sub>4</sub> samples were studied. The results indicated that luminescent properties of BaWO<sub>4</sub>:Dy<sup>3+</sup> depended on the Dy<sup>3+</sup> concentration, and the inner energy could transfer from to Dy<sup>3+</sup>. The quality of the light was checked by estimating CIE parameters, and the results showed that BaWO<sub>4</sub>:Dy<sup>3+</sup> was a potential candidate as blue-green luminescent materials in white LED because of its excellent emission spectrum excited by UV light.
基金supported by the National Natural Science Foundation of China through No.81872320,31600730,81602496,and 81272317the Innovation and University Promotion Project of Guangdong Pharmaceutical University through No.2017KCXTD020.W.C.
文摘Dear Editor,Melanoma,squamous cell carcinoma(SCC),and basal cell carcinoma(BCC)are three major types of skin cancer.Among them,melanoma is the most severe form and accounts for~4%of all newly diagnosed cancers annually in the United States.It is estimated that approximately 9500 people are diagnosed with skin cancer every day,and more than 1 million Americans are living with melanoma.Melanoma treatment is still a major challenge in the clinic.Photodynamic therapy(PDT)is composed of targeted ablation and immune activation,is less invasive than other therapies and has been widely used in the treatment of various cancers.
