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A Novel Microwave Humidity Sensor Based on Resonant Cavity Perturbation Method

IEEE SENSORS JOURNAL 2022年第23期22卷 22571-22581页

作者： Shi, Shuie Gao, Yang Zhang, Yu Zhao, Jiamei Henan Normal Univ Coll Elect & Elect Engn Xinxiang 453000 Peoples R China China Inst Radio Wave Propagat Xinxiang Peoples R China Henan Normal Univ Sch Elect & Elect Engn Xinxiang 453000 Peoples R China

This article proposes a novel humidity sensor using a microwave resonant cavity as the sensing device. This sensor comprises a high-quality factor resonant cavity and frequency detection circuits. The working frequency of the resonator is 9.6 GHz, it has the characteristics that the resonance frequency can be adjusted, and it is designed with embedded air guide holes to allow moist air to enter the interior of the resonant cavity. According to the perturbation theory, when humid air is distributed in the resonator's sensing area, the resonator's resonant frequency changes according to different relative humidity (RH) levels. Then, the frequency detection circuit is used to detect the resonance frequency change, and the RH level related to the shift in the resonance frequency can be obtained. In order to get more accurate measurement results, a temperature and atmospheric pressure compensation algorithm is introduced to correct the measurement results. Experiments show that the proposed humidity sensor effectively detects humidity in an RH environment of 20%-95%. It has the characteristics of fast detection speed and high stability, which avoids the need to use the conventional detection method of the vector network analyzer.

关键词： correction algorithm frequency detection perturbation relative humidity (RH) resonant cavity

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Improvements in road geometry measurement using inertial measurement systems in datalog vehicles

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MEASUREMENT 2011年第1期44卷 102-112页

作者： Jimenez, Felipe Univ Politecn Madrid Inst Univ Invest Automovil INSIA Madrid 28031 Spain

The development of ever more accurate and detailed digital maps is one of the requirements being imposed by new driver assistance systems being fitted in vehicles. Data log vehicles are one of the options to develop these maps. Of the instruments available for measuring road geometry, we must distinguish inertial systems from those of absolute satellite positioning. Although the usual thing is to combine both systems, their limitations must be examined in order to define the scope of each system. Inertial systems give a cumulative error as the distance travelled increases, and this must be evaluated. This paper proposes a way of estimating the error committed in horizontal alignment through the law of uncertainty propagation. Furthermore, these systems enable road grade and superelevation to be measured, but these measurements are conditioned by vehicle dynamics. The proposal put forward is based on a correction algorithm through simulation with a vehicle mathematical model. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Road geometry Inertial measurement system Uncertainty correction algorithm Vehicle dynamics

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Combining deterministic and Monte Carlo calculations for fast estimation of scatter intensities in CT

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PHYSICS IN MEDICINE AND BIOLOGY 2006年第18期51卷 4567-4586页

作者： Kyriakou, Yiannis Riedel, Thomas Kalender, Willi A. Univ Erlangen Nurnberg Inst Med Phys D-8520 Erlangen Germany

A side effect of increased volume coverage by using multi-row and flat-panel detectors in computed tomography ( CT) is the concurrently growing contribution of scattered radiation to the measured signal. In order to investigate the effect of scatter on x-ray projections used for CT imaging, our study aimed at the development of a simulation tool for fast calculation of primary and scatter intensities. We developed a deterministic method to assess the contribution of single-scatter events to the measured signal. The investigation of multiple scatter by Monte Carlo simulations showed that it results in a smooth signal as compared to single scatter. A hybrid method is proposed in order to optimize the performance of the scatter simulation: a fast and exact analytical calculation of the single-scatter intensity combined with a coarse Monte Carlo ( MC) estimate of multiple scatter to reduce overall computational expenses, while assuring an acceptable signal quality. The results of the hybrid simulation of total scatter were in excellent agreement with the corresponding MC only simulations, thereby allowing us to reduce computational time by orders of magnitude. Estimates of two-dimensional scatter distributions for flat-panel CT imaging took about 30-40 s (per projection). The hybrid method provides a realistic simulation of x-ray scatter and offers a basis for scatter correction approaches.

关键词： X-RAY SCATTER CONE-BEAM CT COMPUTED-TOMOGRAPHY DIAGNOSTIC-RADIOLOGY correction algorithm RADIATION FLUOROSCOPY SIMULATION GRIDS MODEL

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Countermeasure to cell dehydration caused terahertz near-field scanning image deterioration

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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024年 304卷 123308页

作者： Li, Zaoxia Lu, Xingxing Chang, Tianying Wei, Dongshan Cui, Hong-Liang Yan, Shihan Jilin Univ Coll Instrumentat & Elect Engn Changchun 130061 Jilin Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen 518055 Guangdong Peoples R China Chinese Acad Sci Chongqing Inst Green & Intelligent Technol Chongqing 400714 Peoples R China

Most biomedical applications of terahertz (THz) imaging are based on distinguishing the dielectric differences of tissues or cells in the THz band. But changes in bio-sample dehydration during the point-scanning process can lead to time-varying deviations in the imaging results. To eliminate the deviations, we proposed a time-varying dehydration kinetic model by analyzing the water diffusion process. The model is verified by experiments and applied to restore each point close to the initial imaging starting state of fresh cellular samples, compensating for the impact of slow speed point-scanning on image deterioration. This methodology has significantly improved the THz super-resolution imaging quality of fresh cellular samples, and successfully restored the cell contours that had been obscured by the cell dehydration over time. Although the dehydration model is developed in THz near-filed imaging, it also pertains to other spectral systems that operate in the raster-scan mode on fresh biosamples.

关键词： Living biological samples THz near-filed scanning imaging Cell dehydration model correction algorithm

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An algorithm to correct for camera vibrations in optical motion tracking systems

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JOURNAL OF BIOMECHANICS 2011年第11期44卷 2172-2176页

作者： Huber, P. Cagran, C. Mueller, W. Graz Univ A-8010 Graz Austria Med Univ Graz A-8010 Graz Austria

Recording and reconstruction of 3D motion capturing data relies on fixed, static camera positions with given inter-camera distances in a laboratory frame. To overcome this limitation, we present a correction algorithm that allows us to address camera movements in moving camera setups. Camera vibrations are identified by comparison of specialized target positions in dynamic measurements with their respective positions in static trials. This results in a 2D shift vector Delta(w) over right arrow with which the individual camera streams are corrected. The capabilities of this vibration reduction procedure are demonstrated in a test setup of four cameras that are (i) separately and (ii) simultaneously perturbed while capturing a static test object. In the former case, the correction algorithm is capable of reducing the reconstruction residuals to the order of the calibrations residual and enables reconstruction in the latter case, which is impossible without any correction. This approach extends the application of marker-based infrared motion tracking to moving and even accelerated camera setups. (c) 2011 Elsevier Ltd. All rights reserved.

关键词： Motion capturing Moving cameras Projective geometry Specialized targets correction algorithm Reconstruction residuals

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Assessment of true intraocular pressure: The gap between theory and practical data

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SURVEY OF OPHTHALMOLOGY 2008年第3期53卷 203-218页

作者： Chihara, Etsuo Sensho Kai Eye Inst Kyoto 6110043 Japan

A precise assessment of the intraocular pressure (TOP) is crucial for diagnosis and decision making regarding treatment modalities in patients with glaucoma. Recent epidemiologic studies show that a difference of only 1 mm Hg in the mean TOP may be critical enough to determine the visual field prognosis in patients with glaucoma. However, the Goldmann applanation tonometer, which is current gold standard, is not precise enough to measure the true TOP within an error of I rum Hg. There are many clinically proposed correction algorithms to correctly measure TOP. However, corrections using only the central corneal thickness and curvature may not be sufficient in each individual case. In this article, previously reported theoretical equations about the effects of corneal topography, modulus of elasticity, and tear film on Goldmann applanation tonometric TOP readings were reviewed, and their discrepancies with clinical or experimental data were analyzed. Thereafter, new tonometers such as the dynamic contour tonometer, the rebound tonometer, and the ocular response analyzer were compared with the Goldmann applanation tonometer and other popular tonometers.

关键词： corneal thickness corneal topography correction algorithm glaucoma intraocular pressure modulus of elasticity refractive surgery tonometer

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Spatial Intensity Distribution Analysis Reveals Abnormal Oligomerization of Proteins in Single Cells

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BIOPHYSICAL JOURNAL 2015年第4期109卷 710-721页

作者： Godin, Antoine G. Rappaz, Benjamin Potvin-Trottier, Laurent Kennedy, Timothy E. De Koninck, Yves Wisemant, Paul W. McGill Univ Dept Phys Montreal PQ Canada Inst Univ Sante Mentale Quebec Quebec City PQ Canada McGill Univ Montreal Neurol Inst Dept Neurol & Neurosurg Montreal PQ H3A 2B4 Canada McGill Univ Program NeuroEngn Montreal PQ Canada Univ Laval Dept Psychiat & Neurosci Quebec City PQ Canada McGill Univ Dept Pharmacol & Therapeut Montreal PQ Canada McGill Univ Alan Edwards Ctr Res Pain Montreal PQ Canada McGill Univ Dept Chem Montreal PQ Canada

Knowledge of membrane receptor organization is essential for understanding the initial steps in cell signaling and trafficking mechanisms, but quantitative analysis of receptor interactions at the single-cell level and in different cellular compartments has remained highly challenging. To achieve this, we apply a quantitative image analysis technique-spatial intensity distribution analysis (SpIDA)-that can measure fluorescent particle concentrations and oligomerization states within different subcellular compartments in live cells. An important technical challenge faced by fluorescence microscopy-based measurement of oligonnerization is the fidelity of receptor labeling. In practice, imperfect labeling biases the distribution of oligomeric states measured within an aggregated system. We extend SpIDA to enable analysis of high-order oligomers from fluorescence microscopy images, by including a probability weighted correction algorithm for nonemitting labels. We demonstrated that this fraction of nonemitting probes could be estimated in single cells using SpIDA measurements on model systems with known oligonnerization state. Previously, this artifact was measured using single-step photobleaching. This approach was validated using computer-simulated data and the imperfect labeling was quantified in cells with ion channels of known oligomer subunit count. It was then applied to quantify the oligomerization states in different cell compartments of the proteolipid protein (PLP) expressed in COS-7 cells. Expression of a mutant PLP linked to impaired trafficking resulted in the detection of PLP tetramers that persist in the endoplasmic reticulum, while no difference was measured at the membrane between the distributions of wild-type and mutated PLPs. Our results demonstrate that SpIDA allows measurement of protein oligomerization in different compartments of intact cells, even when fractional mislabeling occurs as well as photobleaching during the imaging process, and revea

关键词： single-step COMPARTMENT SINGLE CELL imaging processes intensity distribution correction algorithm Oligomerisation Photobleaching cell level Fluorescence microscopy

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Investigating three-dimensional and rotational effects on wind turbine blades by means of a quasi-3D Navier-Stokes solver

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JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME 2000年第2期122卷 330-336页

作者： Chaviaropoulos, PK Hansen, MOL CRES Ctr Renewable Energy Sources Dept Res & Dev Pikermi Attiki 19009 Greece Tech Univ Denmark Dept Energy Engn Fluid Mech Sect DK-2800 Lyngby Denmark

Three-dimensional and rotational viscous effects on wind turbine blades are investigated by means of a quasi-3D Navier-Stokes model. The governing equations of the model are derived from the 3-D primitive variable Navier-Stokes equations written in cylindrical coordinates in the rotating frame of reference. The latter are integrated along the radial direction and certain assumptions are made for the mean values of the radial derivatives. The validity of these assumptions is cross-checked through fully 3-D Navier-Stokes calculations, The resulting quasi-3D model suggests that three-dimensional and rotational effects be strongly related to the local chord by radii ratio and the twist angle, The equations of the model are numerically integrated by means of a pressure correction algorithm. Both laminar and turbulent flow simulations are performed. The former is used for identifying the physical mechanism associated with the 3-D and rotational effects, while the latter for establishing semiempirical correction laws for the load coefficients, based on 2-D airfoil data. Comparing calculated and measured power curves of a stall controlled wind turbine, it is shown that the suggested correction laws may improve significantly the accuracy of the predictions. [S0098-2202(00)02702-4].

关键词： Rotational correction algorithm Three Dimensions Economic Resources Solvers flow simulation Wind Energy Conversion Systems wind turbine blade radial direction CYLINDRICAL COORDINATES

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The spatial correlation problem of noise in imaging deblurring and its solution

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2018年 56卷 167-176页

作者： Yang, Chenwei Feng, Huajun Xu, Zhihai Li, Qi Chen, Yueting Zhejiang Univ State Key Lab Modern Opt Instrumentat Zheda Rd 38 Hangzhou 310027 Zhejiang Peoples R China

We describe the spatial correlation problem of noise in colour digital images and analyse its cause. Pixel correlated image processing procedures, such as CFA colour interpolation and colour space transformation, mainly lead to this problem. Considering this problem, we propose a new noise model based on a joint Gaussian probability distribution. Furthermore, we present an algorithm that makes the revised noise model fit the existing image deconvolution well. The parameters of our algorithm depend only on the image processing procedures of the imaging system. Finally, we apply the proposed algorithm to revise two typical image deconvolution methods and perform simulations and real-world experiments. Both the quantitative indicators and visual performance of the image deblurring results show that the revised deconvolution methods based on our noise model behave better in reducing the noise and ringing artefacts, thus improving the image quality compared with the methods that use the original noise model. (C) 2018 Elsevier Inc. All rights reserved.

关键词： Spatial correlation coefficient Noise probability distribution model Colour interpolation Colour space transformation correction algorithm Image deblurring

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Nonmetric correction of Lens Distortion Based on Entropy Measure

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SCIENTIFIC PROGRAMMING 2018年第Pt.1期2018卷 9-9页

作者： Chen, Tianfei Sun, Lijun Zhang, Qiuwen Wu, Xiang Wu, Defeng Henan Univ Technol Sch Elect Engn Zhengzhou 450001 Henan Peoples R China Zhengzhou Univ Light Ind Coll Comp & Commun Engn Zhengzhou 450002 Henan Peoples R China Jimei Univ Marine Engn Inst Xiamen 361021 Fujian Peoples R China

In the real vision system, lens always inevitably contains nonlinear distortion, which leads to geometric distortion of digital image, so it must be corrected. In this paper, a nonmetric correction algorithm for lens distortion based on entropy measure is proposed. The algorithm uses the imaging characteristics of the space line in the ideal perspective model, and the distortion entropy is defined to measure the degree of lens distortion. For distortion curves with different distribution, the calculation dimension of distortion entropy measure is uniform, which can reduce the influence of curve inhomogeneity. On this basis, the modified distortion entropy measure with normalized weight is put forward to enhance the capability of noise suppression, and the distortion correction performance of the traditional interior point optimization algorithm, basic artificial bee colony (ABC) algorithm, and Gbest-guided artificial bee colony (GABC) algorithm is compared and analyzed. The simulation experiments demonstrate that the correction performance of GABC to optimize the modified distortion entropy measure with normalized weight is best, and it has strong robustness to noise. Finally, the actual image distortion correction examples verify the effectiveness of the proposed algorithm.

关键词： Noise robustness Digital images Optimization algorithms Nonlinear distortion algorithms entropy Noise suppression geometric distortion correction algorithm simulation test LENS DISTORTION

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