- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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The upconversion photoluminescence and temperature sensing abilities of Pb(Zn1/3Nb2/3)O3-9PbTiO3 crystals induced by Er3+/Yb3+ doping
摘要： Er3+/Yb3+-doped Pb(Zn1/3Nb2/3)O3-9PbTiO3 ferroelectric crystals were grown by the high-temperature solution method. The micromorphology, phase structure, and upconversion photoluminescence of obtained crystals were analyzed and investigated. As the results suggest, the crystals displayed typical lamellar growth and possessed a pure perovskite structure. Excited by a 980 nm laser, the characteristic upconversion (UC) emissions of Er3+ were observed at room temperature. The luminescence intensity improved with the increasing of excitation power and reached its maximum at 1056 mW. Two-photon process was demonstrated at lower power range. As the temperature increased from 213 to 493 K, the luminescence intensity weakened continuously. An apparent difference in variation trend between two thermally coupled levels (2H11/2 and 4S3/2) was also observed, which was ascribed to the redistribution of electrons at two levels at the heating process. Based on this dependence, the temperature sensing abilities were examined with the help of the fluorescence intensity ratio (FIR) technique. The absolute sensitivity SA increased in the measurement temperature range and its maximum of 0.0033 K-1 was obtained at 493 K. Moreover, low conversion from incident light into heat was also demonstrated, which indicates the feasibility for crystal luminescence at high power pumping. These results make Er3+/Yb3+-doped Pb(Zn1/3Nb2/3)O3-9PbTiO3 crystals become a promising candidate in optical devices and temperature sensors.
关键词： Two-photon process,Temperature sensing,FIR technique,Ferroelectric crystals,UC emissions
更新于2025-09-23 15:23:52
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Enhancing defects characterization in pulsed thermography by noise reduction
摘要： In the field of NDT techniques for aeronautic components of composite materials, the development of automatic and robust approaches for defect detection is largely desirable for both safety and economic reasons. This paper introduces a novel methodology for the automatic analysis of thermal signals resulting from the application of pulsed thermography. Input thermal decays are processed by a proper FIR filter designed to reduce the measurement noise, and then modeled to represent both sound regions and defective ones. Output signals are thus fitted on an exponential model, which approximates thermal contrasts with three robust parameters. These features feed a decision forest, trained to detect discontinuities and characterize their depths. Several experiments on actual sample laminates have proven the increase of the classification performance of the proposed approach with respect to related ones in terms of the reduction of missing predictions of defective classes.
关键词： FIR filter,Decision forest,Pulsed thermography,Model approximation
更新于2025-09-23 15:23:52
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Multichannel luminescence properties and ultrahigh-sensitive optical temperature sensing of mixed-valent Eu2+/Eu3+ co-activated Ca8ZrMg(PO4)6(SiO4) phosphors
摘要： A novel dual-emitting Ca8ZrMg(PO4)6(SiO4): (Eu3+, Eu2+) phosphors with ultrahigh-sensitive optical temperature sensing are prepared by a conventional solid-state method. The Eu2+/Eu3+ co-activated Ca8ZrMg(PO4)6(SiO4) phosphors exhibit efficient dual-mode emissions with an intense, broad blue emission peaked at 414 nm and a relative bright red-emitting centered at 614 nm under 297 nm UV-light excitation, respectively. Furthermore, the fluorescence intensity ratio (FIR) technology is applied to analyze the optical temperature sensing performance of Ca8ZrMg(PO4)6(SiO4): (Eu3+, Eu2+) phosphors. Based on different thermal quenching behavior of Eu2+ and Eu3+ dual-emitting centers, linear temperature-dependent FIR between Eu2+ and Eu3+ is obtained. The maximal absolute sensitivity reaches as high as 5.94% K-1, which is superior to that for the other luminescent temperature sensing materials reported previously. Analyses of the temperature-dependent photoluminescence spectra and configurational coordinate diagrams for Ca8ZrMg(PO4)6(SiO4): (Eu3+, Eu2+) phosphors indicate that the temperature-sensitive variation in FIR of Eu2+ to Eu3+ is originated from the difference in thermal quenching activation energy for 5d→4f transition of Eu2+ and 5D0→7FJ (J=1, 2, 4) transitions of Eu3+. These results reveal that the Ca8ZrMg(PO4)6(SiO4): (Eu3+, Eu2+) phosphors show glorious potential in high temperature optical thermometry.
关键词： Co-activated,Ca8ZrMg(PO4)6(SiO4),Optical temperature sensing,FIR
更新于2025-09-23 15:23:52
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Area-Efficient Analog FIR Filter for Multi-Level Optical Transmission; 多値光伝送歪み補償に用いる小面積アナログFIRフィルタ;
摘要： The transmission of waveforms through optical fiber usually results in some waveform distortion. To smoothen this distortion, digital finite-impulse response (FIR) filters are commonly employed. Digital FIR filters require a relatively large area for digital signal processing (DSP) on IC chip, so an analog FIR filter is adopted. According to past researches, it is possible to realize a small area circuit by using a CMOS inverter as a delay circuit. However, number of delay circuits employing CMOS inverter increases N/2 for Multi-Level optical transmission. Therefore, we propose a new multiplier and attempted to reduce the circuit area of 4 PAM analog FIR filter. According to the estimation using SPICE simulation, it can be expected to reduce the area by 25% by using the proposed configuration.
关键词： analog FIR filter,CMOS inverter,gilbert cell,multi-level,28 nm FDSOI,optical transmission
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Efficient Multirate Filter Bank Generation with Full Spectral Utilization
摘要： An engine for generating FIR filters of bandwidths that are arbitrary multiplications of a particular quantity are proposed. The design is based on first replacing (cid:2208) by (cid:2208)(cid:2168), where (cid:2168) is an integer, in a low pass filter to result in a multiband filter with arbitrarily sharp transition band. The complement of this multiband filter is also generated. The important step in the proposed design is to feed this into a polyphase filter bank structure to isolate each band. The same is done to the complement of the multiband filter using a second polyphase filter bank structure. This way we have separate bands that could be combined with perfectly flat magnitude response and linear phase. It is shown that all combinations of individual bands could be computed in minimum possible logarithmic time while using the minimum number of additions. In this way, we have a structure to generate any filter response within the smallest band in the multiband structure using few additions. The filters could be left as complex i.e. single band or could be made real with addition to their corresponding conjugates at the cost of losing half the filter bands. The proposed dual filter bank structure could result in a multicarrier communications system that achieves full spectral utilization.
关键词： Full spectral utilization,FBMC,FIR filters,Polyphase,Multirate filter bank,Multicarrier communications
更新于2025-09-23 15:21:01
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Study on the in-process measurements of the surface roughness of Douglas fir green veneers with the use of laser profilometer
摘要： The presented research concerns the use of a laser profilometer to measure the surface roughness of green Douglas fir heartwood veneers during the peeling process. It investigates the effect of various process parameters on the surface quality. Three experiments were carried out with a single variable factor for each experiment: log centration, soaking temperature and cutting speed. Moreover, the origin of the surface roughness of Douglas fir green veneers was investigated. The study shows that laser profilometer seems to be a useful equipment in online measurement of surface roughness of green veneers. Based on the experiment results it was stated that surface roughness of Douglas fir veneers is characterized by large differentiation depending on the location on the veneer. The performed analysis shows that the surface roughness of Douglas fir green veneer could be improved when using relatively high cutting speed, not too high steaming temperature and logs with a centered core. The presented study shows that the laser profilometer can be effectively applied to the measurement and evaluation of green veneers during the peeling process and that there is still an area to develop this methodology.
关键词： peeling process,laser profilometer,Douglas fir,green veneers,surface roughness
更新于2025-09-23 15:19:57
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FIR Detector Sensitivity, Dynamic Range, and Multiplexing Requirements for the Origins Space Telescope (OST)
摘要： Spectroscopic, cold, space-based mid-to-far-infrared (FIR) missions, such as the Origins Space Telescope, will require large (tens of kilopixels), ultra-sensitive FIR detector arrays with sufficient dynamic range and high-density multiplexing schemes for the readout, in order to optimize the scientific return while staying within a realistic cost range. Issues like power consumption of multiplexers and their readout are significantly more important for space missions than they are for ground-based or suborbital applications. In terms of the detectors and their configuration into large arrays, significant development efforts are needed even for both of the most mature candidate superconducting detector technologies, namely transition edge sensors and (microwave) kinetic inductance detectors. Here we explore both practical and fundamental limits for those technologies in order to lay out a realistic path forward for both technologies. We conclude that beyond the need to enhance the detector sensitivities and pixel numbers by about an order of magnitude over currently existing devices, improved concepts for larger dynamic range and multiplexing density will be needed in order to optimize the scientific return of future cold FIR space missions. Background-limited, very high spectral resolution instruments will require photon-counting detectors.
关键词： Space missions,FIR astronomy,TES,MKID
更新于2025-09-23 15:19:57
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[ACM Press the 2018 International Conference - Prague, Czech Republic (2018.10.12-2018.10.14)] Proceedings of the 2018 International Conference on Sensors, Signal and Image Processing - SSIP 2018 - Design of FIR Filter Based on FPGA
摘要： The filter has become an important device when people use for communication and deal with all kinds of signals. FPGA is very suitable for digital signal processing. And it is very good for designing digital filter by using FPGA. A FIR digital filter is designed based on FPGA in this paper, It can assure arbitrary amplitude-frequency characteristic. The hardware design is from Altera company. AD and DA is used in the system because the input and output of this system is digital signal. In order to achieve a high transmission speed, the design was simulated using the System Generator for FPGA. The use of simulation can greatly reduce the cost of the experiment.
关键词： VHDL,FIR,Filter,FPGA
更新于2025-09-19 17:15:36
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Unified Image Fusion Framework with Learning-Based Application-Adaptive Importance Measure
摘要： This paper presents a novel unified image fusion framework based on an application-adaptive importance measure. In the proposed framework, an important area is selected using the importance measure obtained for each image type in each application. The key is to learn this application-adaptive importance measure that can select the important area irrespective of the input image type without manually designing the algorithm for each application. Then, the fused intensity is generated using Poisson image reconstruction. Experimental results demonstrate that the proposed framework is effective for various applications including depth-perceptible image enhancement, temperature-preserving image fusion, and haze removal.
关键词： RGBD,NIR,Image fusion,FIR,Image enhancement
更新于2025-09-10 09:29:36
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Optical investigation of Er3+ and Er3+/Yb3+ doped zinc-tellurite glass for solid-state lighting and optical thermometry
摘要： Er3+ and Er3+/Yb3+ doped zinc tellurite (ZnO/TeO2) glasses were prepared using melt quenching technique. Spectroscopic properties of the glasses were studied by absorption spectroscopy, luminescence spectroscopy, and color chromaticity coordinates (CIE-1931) measurements. Upconverted-emission intensities and the CIE-1931 coordinates were strongly affected by the presence of Yb3+ ion, as well as the excitation power density of 975 nm laser light. Effect of temperature on green upconverted-emissions from two thermally coupled 2H11/2 and 4S3/2 levels of Er3+ ions were measured and fluorescence intensity ratio technique was applied to investigate the temperature sensing properties. High sensitivity and short response time properties make ZnO/TeO2 glasses a very good candidate for non-contact optical temperature sensor applications. The maximum sensitivity of the glasses doped with Er3+ and Er3+/Yb3+ were found to be 72×10-4 K-1 and 120×10-4 K-1 at 429 K, respectively which are much higher than previously reported temperature sensors based on Er3+ ion doped materials. Hence, Er3+/Yb3+ doped zinc-tellurite glass can be more suitable than that of doped with Er3+ ions only for color tunable solid-state lighting and non-contact optical thermometry applications.
关键词： Solid-state lighting,non-contact optical thermometry,fluorescence intensity ratio (FIR),zinc-tellurite glass,upconversion
更新于2025-09-09 09:28:46