- 标题
- 摘要
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- 实验方案
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Dual-wavelength thulium/holmium-doped fiber laser generation in 2 <i>μ</i> m region with high side-mode suppression ratio
摘要： We demonstrate a dual-wavelength laser with emission in the 2 μm wavelength region using a thulium/holmium co-doped fiber and a non-adiabatic tapered fiber as a comb filter. The configuration employed a backward pumping scheme and dual-wavelength laser was generated at 2023.53 and 2032.82 nm. The side-mode suppression ratio (SMSR) is more than 44 dB with overall good stability performance. The proposed configuration presents a simple yet practical scheme of generating 2 μm dual-wavelength laser with good SMSR. This investigation may offer a more efficient yet eye safe dual-wavelength related applications for end users.
关键词： comb filter,tapered fiber,side-mode suppression ratio,thulium/holmium-doped fiber laser,dual-wavelength laser
更新于2025-11-28 14:23:57
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A widely tunable bandpass filter adopting novel fully tunable resonators
摘要： A widely tunable bandpass filter adopting a novel fully tunable resonator is proposed in this letter. The fully tunable resonator is mainly consisted of an open ring, a frequency tuning structure, and a coupling tuning structure. Adopting the fully resonators, the center frequency, the input/output external Q value, and the coupling coefficients can be tuned at the same time. And the tuning range of a tunable filter adopting the novel fully tunable resonators can be expanded. The fully tunable resonators can be combined to achieve more excellent suppression performance. A widely tunable bandpass filter consisted of five fully tunable resonators with 86.5% frequency tuning range is designed, fabricated, and measured. The simulated results are in good agreement with the measured ones.
关键词： widely tunable filter,coupling tuning structure,open ring,fully tunable resonators,more excellent suppression
更新于2025-09-23 15:23:52
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Detection of divalent copper with improved accuracy by dual suppression of electrochemiluminescent recovery
摘要： This work is to construct an electrochemiluminescent (ECL) sensor with improved accuracy for the detection of Cu2+. The improved accuracy is achieved by utilizing a reaction system to realize Cu2+ dose-dependent dual suppression of ECL recovery from gold nanoparticle-graphitic carbon nitride nanosheet nanohybrid (Au-CNNS) film. The ECL sensor shows sensitive response to Cu2+ in the concentration range of 5 nM to 500 nM with an enlarged slope, and high specificity attributed to the high affinity of CNNS-Cu2+ complex and the high catalytic activity of Cu(NH3)6 2+ to decompose H2O2 in the reaction system. The proposed ECL sensor with improved accuracy may prove valuable in future biomedical applications.
关键词： dual suppression,electrochemiluminescent sensor,copper,graphitic carbon nitride nanosheets
更新于2025-09-23 15:23:52
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Predicting postoperative delirium and postoperative cognitive decline with combined intraoperative electroencephalogram monitoring and cerebral near-infrared spectroscopy in patients undergoing cardiac interventions
摘要： Studies have associated electroencephalogram (EEG) suppression with postoperative delirium (POD) and postoperative cognitive decline (POCD). Otherwise, improving cerebral tissue oxygen saturation (rScO2) seems beneficial. No study has evaluated the impact of EEG suppression and decreased rScO2 on the incidence of POD and POCD when the intraoperative management of patients is performed with a depth-of-anesthesia (DOA) monitor and a cerebral oximetry. In this prospective study patients undergoing cardiac interventions were monitored with the NeuroSENSE? DOA monitor and bilateral cerebral oximetry. An algorithm was used to optimize cerebral oxygenation. EEG suppression was presented as total area under the curve (AUC) of suppression ratio (SR) > 0 s (AUC EEGSR>0s). Cerebral desaturation was defined as AUC of 25% drop of oximetry values as compared to baseline. POD was evaluated by the chart review method. POCD was defined as a Z-score ≤ 2 based on Mini Mental State Examination at baseline and day 5 or if the patient reported any cognitive decline at 3 and at 6 months postoperatively. Among the 1616 patients, 1513 underwent normothermic surgery and were further analyzed. POD and POCD were respectively evaluated in 1504 and 1350 patients of whom 303 (20%) and 270 (20%) were respectively diagnosed positive. Having experienced high magnitudes of EEG suppression (fourth quartile of AUC EEGSR>0s) was significantly associated with POD (OR = 2.247; 95% CI = 1.414–3.571; P = 0.001). Low rScO2 at the end of surgery was statistically associated with POCD (OR = 0.981; 95% CI = 0.965–0.997; P = 0.018). The results of our study show that the degree of intraoperative EEG suppression on one hand, and low rScO2 at the end of procedure on the other hand, are associated with respectively POD and POCD in patients undergoing cardiac interventions.
关键词： Burst suppression,Postoperative cognitive decline,Postoperative delirium,Cerebral oximetry,Depth-of-anesthesia monitor
更新于2025-09-23 15:23:52
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Multiple limited-angles computed tomography reconstruction based on multi-direction total variation minimization
摘要： Accurate computed tomography (CT) reconstruction from incomplete projections is an important research topic. Sparse sampling and limited-angle sampling are two effective ways to reduce the X-ray radiation dose or the scanning time. However, it is technically complicated to realize sparse sampling in medical CT since the tube power or the pre-patient collimator is difficult to be switched frequently. Limited-angle sampling makes it difficult to reconstruct an accurate image. The developed multiple limited-angles (MLA) sampling scheme could well balance the technical implementation complexity and the CT reconstruction difficulty. It does not require frequent switching of the tube power or the pre-patient collimator. The data correlation of the acquired projections is lower than that in limited-angle sampling. Using the projections acquired by MLA sampling, CT images reconstructed by the total variation minimization (TVM) method suffer from shading artifacts. Because the artifacts are distributed in several fixed directions, the artifact-suppression reconstruction model based on multi-direction total variation was designed for MLA CT reconstruction in this work. The multi-direction total variation minimization (MDTVM) was utilized to solve the optimization model. Experiments on digital phantoms and real projections indicated that MDTVM can better suppress the shading artifacts than TVM.
关键词： image reconstruction,total variation minimization,computed tomography,limited-angle sampling,artifacts suppression
更新于2025-09-23 15:23:52
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Review of Infrared signature suppression systems using optical blocking method
摘要： With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line-Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.
关键词： IR signature level,Performance penalty,Engine back-pressure,IR signature suppression,Optical blocking
更新于2025-09-23 15:23:52
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[IEEE 2018 17th International Conference on Ground Penetrating Radar (GPR) - Rapperswil, Switzerland (2018.6.18-2018.6.21)] 2018 17th International Conference on Ground Penetrating Radar (GPR) - Noise suppression of GPR data using Variational Mode Decomposition
摘要： Ground penetrating radar (GPR) has been used in the many aspects, such as civil engineering and the earth sciences. And the analysis and noise suppression of GPR data have always been the research focus. In this study, a new self-adaptive time-frequency decomposition tool called the variational mode decomposition (VMD) is introduced. We use the VMD method to derive a set of stationary sub-components, and based on the decomposition, we separate the valid signals and the components which are corresponded to the noise. One trace of GPR data are given to test the effect of the VMD decomposition, and the empirical mode decomposition (EMD) is also employed as a comparison. And a primary noise-suppression method based on the VMD scheme is also proposed. The application of the field GPR data further demonstrates the better performance of the proposed method in both noise suppression and the retention of geophysical events.
关键词： ground penetrating radar (GPR),mode decomposition,variational mode decomposition (VMD),noise reduction or suppression
更新于2025-09-23 15:23:52
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Adaptive Sidelobe Cancellation Technique for Atmospheric Radars Containing Arrays with Nonuniform Gain
摘要： The design and performance evaluation is presented of a partially adaptive array that suppresses clutter from low elevation angles in atmospheric radar observations. The norm-constrained and directionally constrained minimization of power (NC-DCMP) algorithm has been widely used to suppress clutter in atmospheric radars, because it can limit the signal-to-noise ratio (SNR) loss to a designated amount, which is the most important design factor for atmospheric radars. To suppress clutter from low elevation angles, adding supplemental antennas that have high response to the incoming directions of clutter has been considered to be more efficient than to divide uniformly the high-gain main array. However, the proper handling of the gain differences of main and sub-arrays has not been well studied. We performed numerical simulations to show that using the proper gain weighting, the sub-array configuration has better clutter suppression capability per unit SNR loss than the uniformly divided arrays of the same size. The method developed is also applied to an actual observation dataset from the MU radar at Shigaraki, Japan. The properly gain-weighted NC-DCMP algorithm suppresses the ground clutter sufficiently with an average SNR loss of about 1 dB less than that of the uniform-gain configuration.
关键词： robust adaptive beamforming,clutter suppression,atmospheric radars,partial adaptivity
更新于2025-09-23 15:23:52
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Rapid Identification of Functional Pyrrolysyl-tRNA Synthetases via Fluorescence-Activated Cell Sorting
摘要： The orthogonal pyrrolysyl-tRNA synthetase/tRNACUA pair and their variants have provided powerful tools for expanding the genetic code to allow for engineering of proteins with augmented structure and function not present in Nature. To expedite the discovery of novel pyrrolysyl-tRNA synthetase (PylRS) variants that can charge non-natural amino acids into proteins site-specifically, herein we report a streamlined protocol for rapid construction of the pyrrolysyl-tRNA synthetase library, selection of the functional PylRS mutants using fluorescence-activated cell sorting, and subsequent validation of the selected PylRS mutants through direct expression of the fluorescent protein reporter using a single bacterial strain. We expect that this protocol should be generally applicable to rapid identification of the functional PylRS mutants for charging a wide range of non-natural amino acids into proteins.
关键词： non-natural amino acids,flow cytometry,mutagenesis,amber codon suppression,genetic code expansion
更新于2025-09-23 15:23:52
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Accurate Determination of Radiation Patterns from Near-Field Measurements in Highly Reflective Environments
摘要： The radiation pattern of an antenna under test is determined from measurements in a highly reflective, fully metallic measurement environment similar to a reverberation chamber. The undesired influence of the reflecting walls is eliminated by processing the data obtained for a large number of frequencies and different probe locations in the chamber. The post-processing concept effectively combines temporal and spatial filtering of the measured signals in an innovative field synthesis concept. S-Band measurements show the effectiveness of the proposed processing concepts. The accuracy is comparable to anechoic measurements, however, for the cost of increased measurement and post-processing effort.
关键词： echo suppression,near-field far-field transformation,antenna measurement
更新于2025-09-23 15:23:52