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oe1(光电查) - 科学论文

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出版时间
  • 2019
  • 2017
研究主题
  • Phased-array
  • Ultrasound-guided high-intensity focused ultrasound (USgHIFU)
  • Targeting accuracy
  • Calibration
  • cryostat
  • low intensity low temperature
  • space solar cells
  • LILT
  • solar cell characterization
  • FSO Communication System
应用领域
  • Optoelectronic Information Science and Engineering
  • Electrical Engineering and Automation
机构单位
  • Galgotias College of Engineering and Technology
  • Shanghai Jiao Tong University
  • Fraunhofer Institute for Solar Energy Systems ISE
270 条数据
?? 中文（中国） ▾

  • Photoluminescence from GaAs nanostructures

    摘要： The confinement properties of semiconductor nanostructures have promising potential in technological application. The main objective of this study is to describe the dependence of Photoluminescence (PL) intensity on different parameters like temperature, excitation wavelength, time and photon energy of GaAs quantum dots (QDs). The model equations are numerically analyzed and simulated with matlab and FORTRAN codes. The experimental fitted values and physical properties of materials are used as data source for our simulation. The result shows that at low temperature the peak is quite sharp, as temperature increases the PL intensity decreases and get quenched at particular thermal energy.

    关键词： quantum confinement,Photoluminescence (PL) intensity,GaAs quantum dots,nanostructures,thermal quenching energy

    更新于2025-09-04 15:30:14

  • Junction-less optical phase shifter loaded silicon Mach Zehnder modulator

    摘要： In this paper, we design and numerically analyze the performance of electrostatic doping (ED) assisted junction-less optical phase shifter loaded silicon Mach-Zehnder (MZM), which is realizable on the 220 nm SOI platform. The proposed phase shifter contains a vertical metal–insulator–semiconductor (MIS) junction and a lateral metal-semiconductor (MS) junction. Change in the refractive index profile inside the rib waveguide, which supports the phase shifter, is achieved by altering the concentration of free carriers via the plasma dispersion effect. Numerical simulation using commercially available TCAD tool and mode solver are used to estimate the performance of the proposed modulator. Two different sets of materials are used as electrodes to realize the MIS-MS charge plasma diode. In one design gold (Au) and silver (Ag) is used as electrode material while the other design utilizes palladium (Pd) and aluminum (Al) as electrode material. The performance of the proposed modulator(s) is extensively studied both in steady state and transient state. A complete analysis of chirp and nonlinear distortion for the proposed modulator are also presented in the paper. Results predict that a maximum of 15.4 dB dynamic extinction ratio (ER) is achievable with a minimum of 3.2 dB insertion loss (IL). The proposed modulator is expected to provide a maximum of 30.3 Gbps operating speed with 22.2 GHz of 3-dB electro-optical bandwidth. Simulation result predicts that the worst case dynamic energy per bit for the proposed ED assisted MZM is approximately 54.4 fJ/bit.

    关键词： work-function,intensity modulator,IMD3,electrostatic doping,plasma dispersion effect,Mach-Zehnder modulator

    更新于2025-09-04 15:30:14

  • AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - L X-ray relative intensity ratios of uranium, lead, hafnium and samarium

    摘要： In this study the L shell X-ray relative intensities ((cid:1835)(cid:3013)(cid:3287)(cid:512)(cid:1835)(cid:3013)(cid:3330), (cid:1835)(cid:3013)(cid:3328)(cid:512)(cid:1835)(cid:3013)(cid:3330) and (cid:1835)(cid:3013)(cid:3329)(cid:512)(cid:1835)(cid:3013)(cid:3330)) for uranium, lead, hafnium and samarium have been measured for several scattering angles (85°, 95°, 105°, 115°, 125° and 135°) at 59.54 keV photon energy by using a Si(Li) detector which has a resolution of 160 eV at 5.9 keV. In previous studies, the (cid:1838)(cid:3082) X-rays were usually found independ on the scattering angles, therefore we found reasonable to give the ratio to the (cid:1838)(cid:3082) X-rays.

    关键词： L X-ray,samarium,relative intensity ratios,uranium,lead,hafnium,scattering angles

    更新于2025-09-04 15:30:14

  • Design and Provision of Traffic Grooming for Optical Wireless Data Center Networks

    摘要： Traditional wired data center networks (DCNs) suffer from cabling complexity, lack flexibility, and are limited by the speed of digital switches. In this paper, we alternatively develop a top-down traffic grooming (TG) approach to the design and provisioning of mission-critical optical wireless DCNs. While switches are modeled as hybrid optoelectronic cross-connects, links are modeled as wavelength division multiplexing (WDM) capable free-space optic (FSO) channels. Using the standard TG terminology, we formulate the optimal mixed-integer TG problem considering the virtual topology, flow conversation, connection topology, non-bifurcation, and capacity constraints. Thereafter, we develop a fast yet efficient sub-optimal solution which grooms mice flows (MFs) and mission-critical flows (CFs) and forward on predetermined rack-to-rack (R2R) lightpaths. On the other hand, elephant flows (EFs) are forwarded over dedicated server-to-server (S2S) express lightpaths whose routes and capacity are dynamically determined based on the availability of wavelength and capacity. To prioritize the CFs, we consider low and high priority queues and analyze the delay characteristics such as waiting times, maximum hop counts, and blocking probability. As a result of grooming the sub-wavelength traffic and adjusting the wavelength capacities, numerical results show that the proposed solutions can achieve significant performance enhancement by utilizing the bandwidth more efficiently, completing the flows faster than delay sensitivity requirements, and avoiding the traffic congestion by treating EFs and MFs separately.

    关键词： intensity allocation,delay analysis,lightpath provisioning,mission-critical data centers,wavelength assignment,hybrid cross-connect,Wavelength routing,blocking probability analysis

    更新于2025-09-04 15:30:14

  • [IEEE 2017 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rochester, MN, USA (2017.5.7-2017.5.10)] 2017 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - The calibration of targeting errors for an ultrasound-guided high-intensity focused ultrasound system

    摘要： Accurate targeting is one indispensable feature of image-guided high-intensity focused ultrasound (HIFU) systems for treatment safety and efficacy. In our previously developed ultrasound-guided phased-array HIFU system, a rotatable imaging probe was mounted into the central hole of applicator for targeting and monitoring. Two-dimensional image sequence of different imaging planes can be obtained by rotation of the probe. The misalignment between the spots predetermined in the image and the spots sonicated in the tissue can result in the ablation of normal tissue outside the targeting volume, and thus targeting error is unavoidable. An acrylic plate internally placing two flat-head bolts was constructed to measure and calibrate the targeting error. The imaging planes were switched from ?90° to 90° with a 30° step, and the targeting errors were measured 12 times for each of these planes before and after calibration. The targeting errors in other imaging planes could be estimated by linear interpolation using the measured errors in the nearest two imaging planes. The coordinates of the spots to be sonicated were corrected in consideration of the targeting errors in the selected imaging plane. After calibration, the mean targeting errors were reduced to 0.30~0.68 mm from 0.86~1.74 mm. Besides, in the ex vivo experiment the needle-thermocouple tip was used as the target which could be identified in the image. The temperature rise measured by the thermocouple during sonication was in accordance with the theoretical result. In conclusion, the calibration of targeting errors is effective for our system, and the targeting accuracy is also capable to ensure safe sonication.

    关键词： Phased-array,Ultrasound-guided high-intensity focused ultrasound (USgHIFU),Targeting accuracy,Calibration

    更新于2025-09-04 15:30:14

  • Machine Learning for 100Gb/s/λ Passive Optical Network

    摘要： To respond the growing bandwidth demand by emerging applications such as fixed-mobile convergence for 5G and beyond 5G, 100Gb/s/λ access network becomes the next research focus of passive optical network (PON) roadmap. Intensity modulation and direct detection (IMDD) technology is still considered as a promising candidate for 100Gb/s/λ PON attributed to its low cost, low power consumption and small footprint. In this paper, we achieve 100Gb/s/λ IMDD PON by using 20G-class optical and electrical devices due to its commercial linear and nonlinear availability. To mitigate the system distortions, neural network (NN) based equalizer is used and the performance is compared with feedforward equalizer (FFE) and Volterra nonlinear equalizer (VNE). We introduce the rules to train and test the data when using NN-based equalizer to guarantee a fair comparison with FFE and VNE. Random data has to be used for training, but for test, both random data and psudo-random bit sequence (PRBS) are applicable. We found NN-based equalizer has the same performance with FFE and VNE in the case of linear distortion only, but outperforms them in strong nonlinearity case. In the experiment, to improve the loss budget, we increase the launch power to 18 dBm, achieving a 30-dB loss budget for 33Gbaud/s PAM8 signal at the system frequency response of 16.2 GHz, attributed to the strong nonlinear equalization capability of NN.

    关键词： neural network (NN),machine learning,intensity modulation and direct detection (IMDD),digital signal processing (DSP),Passive optical network (PON)

    更新于2025-09-04 15:30:14

  • [IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Clumped Nuclei Segmentation with Adjacent Point Match and Local Shape-Based Intensity Analysis in Fluorescence Microscopy Images

    摘要： Highly clumped nuclei captured in fluorescence microscopy images are commonly observed in a wide spectrum of tissue-related biomedical investigations. To ensure the quality of downstream biomedical analyses, it is essential to accurately segment clustered nuclei. However, this presents a technical challenge as fluorescence intensity alone is often insufficient for recovering the true nuclei boundaries. In this paper, we propose an segmentation algorithm that identifies point pair connection candidates and evaluates adjacent point connections with a formulated ellipse fitting quality indicator. After connection relationships are determined, we recover the resulting dividing paths by following points with specific eigenvalues from the image Hessian in a constrained searching space. We validate our algorithm with 560 image patches from two classes of tumor regions of seven brain tumor patients. Both qualitative and quantitative experimental results suggest that our algorithm is promising for dividing overlapped nuclei in fluorescence microscopy images widely used in various biomedical research.

    关键词： clumped nuclei segmentation,fluorescence microscopy images,adjacent point match,local shape-based intensity analysis

    更新于2025-09-04 15:30:14

  • Fracture behaviors of a piezoelectric-piezomagnetic sandwich structure under electromechanical loads: plane problem

    摘要： The fracture behaviors of a piezoelectric-piezomagnetic sandwich structure with an eccentric internal crack subjected to two kinds of in-plane electromechanical loads have been studied in this paper. A singular integral equation with Cauchy kernel is obtained by means of Fourier transform and further solved by using Gauss-Chebyshev technique. Then the stress intensity factors are obtained and some numerical results are presented to show the e?ects of the material properties, structure geometries, electromechanical loads and the crack location on the stress intensity factors. The conclusions of the present paper may be useful for the design and fracture prediction of layered piezoelectric-piezomagnetic structures.

    关键词： sandwich structure,stress intensity factor,plane strain problem,integral transformation,Piezoelectric-Piezomagnetic composite

    更新于2025-09-04 15:30:14

  • Langmuir–Hinshelwood and Light-Intensity Dependence Analyses of Photocatalytic Oxidation Rates by Two-Dimensional-Ladder Kinetic Simulation

    摘要： Though photocatalytic reactions gather enormous attention, dependences of light intensity and reactant concentration have not been concurrently expressed clearly. In the previously reported studies, a quadratic formula equation obtained from the conventional analysis using the concentration of electron?hole pairs has been modified. In this report we numerically simulated the reaction with a two-dimensional(2D)-ladder kinetics without using electron?hole concentrations. In fundamental processes, (i) photoabsorption, (ii) reduction, (iii) oxidation, and (iv) recombination, were treated as the transitions between the states of each powder characterized by the numbers of possessing negative and positive charges. Through the numerical 2D-ladder simulation with various rate constants, the light-intensity (I) dependence of the oxidation rate was found to be fully expressed by involving the square of the intrinsic quantum yield into the square root part of the well-known quadratic formula equation. The square root dependence of the reaction rate, r ∝ I1/2, could be expected only when the rate of the reduction is extremely smaller than the recombination rate at the normal light intensity. Then, the resultant equations obtained with this 2D-ladder simulation were transformed to the equation for Langmuir?Hinshelwood kinetics with two parameters, rL and KL, which correspond to the intrinsic oxidation rate and the adsorption equilibrium constant of the reactant, respectively. Light-intensity dependence of KL was expressed by adding two terms proportional to I2 to both the adsorption and desorption rate constants. The reported experimental data sets of the decomposition rates for phenol and 4-chlorophenol were fitted with the proposed equation, and then from the obtained parameter values the formation rate of (cid:129)O2? could be estimated and found to be compatible to that which has been experimentally measured. Thus, the present analytical treatment is actually the simple and useful method to understand the dependencies of reactant concentration and light-intensity on the photocatalytic oxidation rates.

    关键词： reactant concentration,photocatalytic reactions,light intensity,Langmuir?Hinshelwood kinetics,two-dimensional-ladder kinetics

    更新于2025-09-04 15:30:14

  • Lidar arc scan uncertainty reduction through scanning geometry optimization

    摘要： Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a ?xed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind ?uctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production prediction. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with ?at terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation.

    关键词： arc scans,wind energy,Doppler lidar,scan geometry optimization,turbulence intensity

    更新于2025-09-04 15:30:14