修车大队一品楼qm论坛51一品茶楼论坛,栖凤楼品茶全国楼凤app软件 ,栖凤阁全国论坛入口,广州百花丛bhc论坛杭州百花坊妃子阁

oe1(光电查) - 科学论文

过滤筛选

出版时间
  • 2018
研究主题
  • golden ratio
  • sampling oscilloscope
  • waveform missing
  • ADC histogram testing method
  • golden section search
  • equivalent-time sampling
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Gunma University
137 条数据
?? 中文（中国） ▾

  • Selective guided sampling with complete light transport paths

    摘要： Finding good global importance sampling strategies for Monte Carlo light transport is challenging. While estimators using local methods (such as BSDF sampling or next event estimation) often work well in the majority of a scene, small regions in path space can be sampled insufficiently (e.g. a reflected caustic). We propose a novel data-driven guided sampling method which selectively adapts to such problematic regions and complements the unguided estimator. It is based on complete transport paths, i.e. is able to resolve the correlation due to BSDFs and free flight distances in participating media. It is conceptually simple and places anisotropic truncated Gaussian distributions around guide paths to reconstruct a continuous probability density function (guided PDF). Guide paths are iteratively sampled from the guided as well as the unguided PDF and only recorded if they cause high variance in the current estimator. While plain Monte Carlo samples paths independently and Markov chain-based methods perturb a single current sample, we determine the reconstruction kernels by a set of neighbouring paths. This enables local exploration of the integrand without detailed balance constraints or the need for analytic derivatives. We show that our method can decompose the path space into a region that is well sampled by the unguided estimator and one that is handled by the new guided sampler. In realistic scenarios, we show 4× speedups over the unguided sampler.

    关键词： Sampling and Reconstruction,Global Illumination,Stochastic Sampling,Monte Carlo

    更新于2025-09-23 15:23:52

  • [IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Tree-Shaped Sampling Based Hybrid Multi-Scale Feature Extraction for Texture Classification

    摘要： Efficiency, distinctiveness and robustness are three main goals for feature extractors in application of texture classification. In this paper, a new feature extractor is designed which aims to achieve these three goals simultaneously. The contributions are threefold. Firstly, a tree-shaped multi-scale sampling structure is proposed to acquire points distributed along two circles and one octagon. Secondly, four histogram vectors are obtained by quantizing the sampling values through a hybrid strategy. In order to suppress the noise, mean filtering is used as a preprocessing step and the four vectors are concatenated to form the discriminant vector. Thirdly, experiments are conducted on different datasets with several well-known feature extractors. The results show that the proposed method improves the classification accuracy effectively and robustly, while has a moderate complexity. The source code is available at: https://github.com/madd2014/TSSHM.

    关键词： texture classification,Feature extraction,multi-scale structure,tree-shaped sampling

    更新于2025-09-23 15:23:52

  • 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

  • Dechirping Compression Method for Nonlinear Frequency Modulation Waveforms

    摘要： This letter proposes a novel dechirp processing method for wideband nonlinear frequency modulation (NLFM) waveform which enables low sampling rate of data. As we know, NLFM waveform can easily realize optimal shape of power spectral density which helps to achieve better pulse compression result with low range sidelobes without signal-to-noise ratio degradation caused by weighting as we usually do for LFM waveforms. In the approach, hamming window is adopted in the generation of the NLFM waveform for better balance on the low range sidelobes and a relative small bandwidth. In dechirp operation, the NLFM radar echoes are mixed with a local reference LFM signal, and thus narrowband signals are resulted and only low sampling rate is needed. The dechirped NLFM signals are then up-sampled and inverse dechirped by software and ?nally matched ?ltering is conducted to complete pulse compression. Both numerically simulated data and real radar data are processed to verify the effectiveness of the proposed method.

    关键词： nonlinear frequency modulation (NLFM),sampling rate,pulse compression,Dechirp processing

    更新于2025-09-23 15:23:52

  • [IEEE 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Cleveland, OH, USA (2018.10.17-2018.10.19)] 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Gaussian Monocycle Pulse Generator with Calibration Circuit for Breast Cancer Detection

    摘要： Gaussian Monocycle Pulses (GMP) play a very important role in a radar-based painless breast cancer detection system. In order to guarantee the detection accuracy, it is necessary to stabilize the pulse width and the amplitude under the influence of the manufacturing variation of MOSFETs. Therefore, in this paper, the GMP generator with a calibration circuit is proposed. The calibration circuit for adjusting the delay time of each path is realized by MOS capacitor array. The proposed GMP generator has a center frequency of 5.5 GHz, -3dB bandwidth from 2.8 GHz to 9.1 GHz, and 498.6 μW power consumption.

    关键词： Gaussian Monocycle Pulse (GMP),equivalent time sampling,breast cancer detection system,calibration circuit

    更新于2025-09-23 15:23:52

  • [IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Effect of Non-Uniform Azimuth Sampling on Sar Image Formation Evaluated at 79Ghz

    摘要： Conventional synthetic aperture radar (SAR) image formation requires uniform sampling along the azimuth direction. These image formation relies on frequency domain algorithms including the Range-Doppler Algorithm (RDA), Chirp-Scaling Algorithm (CSA) [1] etc, that make use of azimuth Fast Fourier Transform, hence the requirement of uniform sampling. While uniform sampling in space is not always achievable, the samples can be interpolated onto a uniform grid given the sampling rate is Nyquist. This paper studies the effect of SAR image formation when the azimuth sampling is not uniform, and not Nyquist in some interval. The results showed that even if there is a wide interval in the middle of the synthetic aperture with no samples, an image can still be formed. This result could be useful when the SAR antenna is a phased array, or when the hardware is generating bursts of pulses followed by a quiet window.

    关键词： Image focusing,Back-Projection,Azimuth Sampling,Synthetic aperture radar

    更新于2025-09-23 15:22:29

  • The investigation of a new fast timing system based on DRS4 waveform sampling system

    摘要： In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two LaBr3:Ce detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV g photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the t 152Gd-21 decay of 152Eu source is measured. The measured lifetime is 45.3(±5.0)ps, very close to the value of the National Nuclear Data Center (NNDC: 46.2((±3.9)ps). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.

    关键词： Waveform sampling system,Excited state lifetime,LaBr3:Ce scintilator,Fast timing technique

    更新于2025-09-23 15:22:29

  • An On-Chip Monitoring Circuit with 51-Phase PLL-Based Frequency Synthesizer for 8-Gb/s ODR Single-Ended Signaling Integrity Analysis

    摘要： An on-chip monitoring circuit using a sub-sampling scheme, which consists of a 6-bit flash analog-to-digital converter (ADC) and a 51-phase phase-locked loop (PLL)-based frequency synthesizer, is proposed to analyze the signal integrity of a single-ended 8-Gb/s octal data rate (ODR) chip-to-chip interface with a source synchronous clocking scheme.

    关键词： on-chip monitoring circuit,sub-sampling,chip-to-chip interface,analog-to-digital converter,phase-locked loop-based frequency synthesizer

    更新于2025-09-23 15:22:29

  • [IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Design Techniques for Incremental Non-Regular Image Sampling Patterns

    摘要： Even though image signals are typically acquired on a regular two dimensional grid, there exist many scenarios where non-regular sampling is possible. Non-regular sampling can remove aliasing. In terms of the non-regular sampling patterns, there is a high degree of freedom in how to actually arrange the sampling positions. In literature, random patterns show higher reconstruction quality compared to regular patterns due to reduced aliasing effects. On the downside, random patterns feature large void areas which is also disadvantageous. In the scope of this work, we present two techniques to design optimized non-regular image sampling patterns for arbitrary sampling densities. Both techniques create incremental sampling patterns, i.e., one pixel position is added in each step until the desired sampling density is reached. Our proposed patterns increase the reconstruction quality by more than +0.5 dB in PSNR for a broad density range. Visual comparisons are provided.

    关键词： Non-Regular Sampling,Image Reconstruction

    更新于2025-09-23 15:22:29

  • SAR Slow Moving Target Imaging Based on Over-Sampling Smooth Algorithm

    摘要： A novel Synthetic aperture radar (SAR) signal processing technique has been proposed which re-focused slow moving targets based on phase retrieval algorithm. After theoretical derivation, we can get that the raw data Fourier magnitude of slow moving targets is approximate to the stationary ones in the SAR system. By applying the Fourier magnitude of received data to phase retrieval algorithms, the blur and defocusing effect caused by the moving of the targets can be eliminated. The simulated results demonstrate the validity of this algorithm.

    关键词： Over-sampling smooth,Slow moving target imaging,Synthetic aperture radar,Phase retrieval

    更新于2025-09-23 15:21:21