- 标题
- 摘要
- 关键词
- 实验方案
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Range-Variant Channel Errors Calibration Algorithm for Multichannel HRWS SAR Imaging
摘要： Azimuth multichannel SAR system can realize high-resolution and wide-swath (HRWS) SAR imaging, which has attracted interests. The azimuth ambiguities of multichannel SAR can be suppressed by digital beamforming (DBF) techniques. However, the presence of inevitable channel errors deteriorates the performance of ambiguity suppression. In this paper, we focus on the research of range-variant channel phase errors. We analyze the effect of radial position errors by using the second order Taylor series to expand the azimuth phase history. It indicates that the radial position errors can be regarded as range-variant phase errors. We divide the raw data into several blocks along range direction. Then we use the azimuth cross-correlation technique to estimate the phase errors of each block data. Compared with the subspace-based calibration techniques, the azimuth cross-correlation technique does not use the information of azimuth ambiguities. Afterwards, the fitting process is employed to estimate the range-variant channel phase errors. Finally, the experiments on real data processing validate the effectiveness of our proposed method.
关键词： channel error calibration,Range-variant,HRWS,cross-correlation,multichannel SAR
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Jeju (2018.10.17-2018.10.19)] 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Performance of SIM/S-QAM FSO Systems with Phase Errors in Gamma-Gamma Turbulence Channels
摘要： In this paper, we study the performance of subcarrier intensity modulation (SIM) squared quadrature-amplitude modulation (S-QAM) free-space optical (FSO) communication systems considering the atmospheric turbulence-induced phase error in fading channel. The atmospheric fading channel is modeled by Gamma-Gamma distribution while the Tikhonov model is used for the turbulence-induced phase error. The numerical results quantitatively show the impact of atmospheric turbulence parameters to the performance of FSO systems in terms of average symbol-error probability (ASEP) and the power penalty. Besides, the theoretical results are validated through Monte Carlo simulation to confirm our analysis.
关键词： Free-space optics (FSO),Phase error.,Atmospheric Turbulence,Fading Channel,Squared quadrature-amplitude modulation (QAM)
更新于2025-09-23 15:22:29
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High Channel Conductivity, Breakdown Field Strength, and Low Current Collapse in AlGaN/GaN/Si δ -Doped AlGaN/GaN:C HEMTs
摘要： This paper reports the AlGaN/GaN/Si δ-doped AlGaN/GaN:C HEMT device on silicon with high channel conductivity, high breakdown ?eld (E-?eld) strength, and low current collapse by using the Si-doped AlGaN back barriers. The Si δ-doped AlGaN back barrier was used to compensate for the reduction of channel conductivity as a result of a carbon-doped semiinsulating GaN buffer layer. The maximum drain current increases from 412 to 720 mA/mm, and peak extrinsic transconductance is improved from 103 to 210 mS/mm. Due to the reduction of electric ?eld between the gate and drain along the GaN channel by inserting the Si δ-doped AlGaN back barrier layer, it can effectively suppress the capture of electrons in channel by carbon-induced accepted traps in the GaN:C buffer. Combined with the high conductivity of Si δ-doped AlGaN back barrier and high resistance of GaN:C buffer, the device showed the high breakdown E-?eld strength and the low speci?c on-resistance. Our proposed device is observed to hold a gate–drain voltage of 769 V at 10 μA/mm (7-μm gate–drain spacing) and 0.53 mΩ · cm2 and the gate-to-drain electric ?eld corresponds to 1.1 MV/cm.
关键词： high channel conductivity,high-voltage device,Si δ-doped AlGaN back barrier,GaN,Current collapse (CC)
更新于2025-09-23 15:22:29
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Van der Waals junction field effect transistors with both n- and p-channel transition metal dichalcogenides
摘要： Two-dimensional (2D) transition metal dichalcogenides (TMDs)-based van der Waals (vdW) PN junctions have been used for heterojunction diodes, which basically utilize out-of-plane current across the junction interface. In fact, the same vdW PN junction structure can be utilized for another important device application, junction field effect transistors (JFETs), where in-plane current is possible along with 2D–2D heterojunction interface. Moreover, the 2D TMD-based JFET can use both p- and n-channel for low voltage operation, which might be its unique feature. Here we report vdW JFETs as an in-plane current device with heterojunction between semiconducting p- and n-TMDs. Since this vdW JFET would have low-density traps at the vdW interface unlike 2D TMD-based metal insulator semiconductor field effect transistors (MISFETs), little hysteresis of 0.0–0.1 V and best subthreshold swing of ~100 mV/dec were achieved. Easy saturation was observed either from n-channel or p-channel JFET as another advantage over 2D MISFETs, exhibiting early pinch-off at ~1 V. Operational gate voltage for threshold was near 0 V and our highest mobility reaches to ~>500 cm2/V·s for n-channel JFET with MoS2 channel. For 1 V JFET operation, our best ON/OFF current ratio was observed to be ~104.
关键词： n-channel,field effect transistors,van der Waals junction,transition metal dichalcogenides,p-channel
更新于2025-09-23 15:21:21
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Suppression of four-wave mixing in a 22?×?10?Gbps dense wavelength division multiplexed system by linearly chirped fiber Bragg gratings
摘要： A scheme comprising two linearly chirped fiber Bragg gratings (LCFBGs) is proposed to suppress four-wave mixing (FWM) effects in a 22×10? Gbps dense wavelength division multiplexed (DWDM) system employing dispersion shifted fiber with 0.2? nm channel spacing. The FWM reduction in our proposed scheme has been studied by varying the input signal power per channel from ? 2 to + 10? dBm. The parameters of LCFBGs are optimized to obtain a maximum quality factor for all 22 channels. The proposed method is effective even at high input power (10?dBm) and provides a simple, cost effective way to improve the transmission performance in DWDM system.
关键词： Dense wavelength division multiplexing (DWDM),Dispersion,Four wave mixing (FWM),Chirped fiber Bragg gratings,Channel spacing
更新于2025-09-23 15:21:21
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Potassium channel-based optogenetic silencing
摘要： Optogenetics enables manipulation of biological processes with light at high spatio-temporal resolution to control the behavior of cells, networks, or even whole animals. In contrast to the performance of excitatory rhodopsins, the effectiveness of inhibitory optogenetic tools is still insufficient. Here we report a two-component optical silencer system comprising photo-activated adenylyl cyclases (PACs) and the small cyclic nucleotide-gated potassium channel SthK. Activation of this ‘PAC-K’ silencer by brief pulses of low-intensity blue light causes robust and reversible silencing of cardiomyocyte excitation and neuronal firing. In vivo expression of PAC-K in mouse and zebrafish neurons is well tolerated, where blue light inhibits neuronal activity and blocks motor responses. In combination with red-light absorbing channelrhodopsins, the distinct action spectra of PACs allow independent bimodal control of neuronal activity. PAC-K represents a reliable optogenetic silencer with intrinsic amplification for sustained potassium-mediated hyperpolarization, conferring high operational light sensitivity to the cells of interest.
关键词： Potassium channel,Neuronal silencing,Photo-activated adenylyl cyclases,Optogenetics,Cardiomyocyte excitation
更新于2025-09-23 15:21:21
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Fluorescence-based high throughput screening technologies for natural chloride ion channel blockers
摘要： Chloride channels represent a group of potential drug targets, their blockers showed significant protecting effect on impaired cells by modulating apoptosis, autophagy and other cell signals. However, clinical drugs with chloride channel inhibitory properties have not yet been developed. Natural product extract becomes an underlying candidate satisfied the clinical requirements for its low toxicity, low cost and abundant sources. Here, a fluorescence-based EYFP-H148Q/I153L-HeLa cell line model was constructed by molecular cloning and verified by Real-time PCR and Western Blotting assay. By using this chloride channel blocker screening model, 7 hit compounds chosen from 6988 natural compounds showed the channel blocking activity. Then the hit compounds were further validated by electrophysiological patch-clamp analysis. Our study preliminarily identified PC-4 as a new chloride channel inhibitors and demonstrated the reliability and sensitivity of fluorescence-based high throughput screening technologies for discovery of biologically active compounds from natural herbal compounds.
关键词： natural compound,high throughput screening,chloride channel blocker,patch clamp
更新于2025-09-23 15:21:21
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Biomimetic Photocurable 3D Printed Nerve Guidance Channels with Aligned Cryomatrix Lumen for Peripheral Nerve Regeneration
摘要： Repair and regeneration of the critically injured peripheral nerves is one of the most challenging reconstructive surgeries. Currently available and FDA approved nerve guidance channels (NGCs) are suitable for small gap injuries, and their biological performance is inferior to that of autografts. Development of biomimetic NGCs with clinically relevant geometrical and biological characteristics such as topographical, biochemical and haptotactic cues could offer better regeneration of the long gap complex nerve injuries. Here, in this study, we present the development and preclinical analysis of a 3D printed aligned cryomatrix filled NGCs along with nerve growth factor (NGF) (aCG+NGF) for peripheral nerve regeneration. We demonstrated the application of these aCG+NGF NGCs in the enhanced and successful regeneration of a critically injured rat sciatic nerve in comparison to random cryogel filled NGCs, multichannel, and clinically preferred hollow conduits as well as gold standard autografts. Our results indicated viz-a-viz similar effect of aCG+NGF NGCs to that of autografts, and not only enhanced the overall regenerated nerve physiology, but could also mimic the cellular aspects of regeneration. This study emphasizes the paradigm that these biomimetic 3D printed NGCs will lead to a better functional regenerative outcome under clinical settings.
关键词： guidance channel,3D printing,nerve regeneration,aligned cryogel,stereolithography
更新于2025-09-23 15:21:21
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Performance analysis of a new OCFHC/QCC vis-a-vis synchronous PC/OOC code using photon count approach
摘要： In this study, the performance of one-coincidence frequency hopping code/quadratic congruence code (OCFHC/QCC) has been analysed and compared with an existing code. The error probabilities of an eight-user optical code division multiple access (OCDMA) system are 4.7934 × 10?9 and 5.9497 × 10?10 for the synchronous prime code/optical orthogonal code (PC/OOC) and OCFHC/QCC, respectively, at the received power level ?15?dBm and data rate 1?Gbps. The improvement in the performance is of the order of 10?1 which becomes better if the received power level increases beyond ?15?dBm. In addition, the effect of variation in code weight, code length and number of wavelengths of the OCFHC/QCC code on the performance of the OCDMA system is also studied. OCFHC/QCC has a simple design methodology, flexibility in choosing the number of wavelengths, large cardinality and superior performance than the synchronous PC/OOC. Furthermore, the performance of the OCFHC/QCC is also analysed in the atmospheric channel. Based on the analysis, it is concluded that this code should be preferred for local area network, multicode keying, and wireless optical communication.
关键词： atmospheric channel,synchronous PC/OOC,OCDMA,OCFHC/QCC,error probabilities
更新于2025-09-23 15:21:21
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing, China (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Research on Counting Algorithm of Residual Feeds in Aquaculture Based on Machine Vision
摘要： The waste of feed has always restricted the development of aquaculture. This paper presents an algorithm that can accurately obtain the residual information of feeds after a feeding event. With the purpose of applying the residual feed counting algorithm to the actual production, we focused on solving problems of counting feed pellets, such as turbid pond water, feed adhesion etc. We carry our experiments with different water turbidity levels and with feed adhesion, and some experiments have over 100 pellets. Experiments show that relative error can still be maintained at about 10% under the condition of turbid water and feed adhesion, which is much better than 20% obtained by other counting algorithm.
关键词： feed counting,turbid water,non-uniform illumination,feed identification,dark channel prior
更新于2025-09-23 15:21:21