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Multi-surface phase-shifting algorithm using the window function fitted by the nonlinear least squares method

JOURNAL OF MODERN OPTICS 2022年第3期69卷 160-171页

作者： Chang, Lin Valyukh, Sergiy He, Tingting Chen, Zhu Yu, Yingjie Shanghai Univ Dept Precis Mech Engn Shanghai 200072 Peoples R China Linkoping Univ Dept Phys Chem & Biol Linkoping Sweden

A multi-surface phase demodulation algorithm is proposed to measure surfaces of the transparent plate simultaneously. A non-linear least-squares method based on the trust region is utilized to fit the window function derived from the characteristic polynomials. The fitted window function requires fewer parameters and has a flexible form, which means the window length can be stretched freely and used flexibly. Then, a multi-surface phase demodulation technique combining the discrete Fourier principle and the fitted window function is investigated, allowing simultaneous reconstruction of the measured front surface, rear surface, and thickness variation. During the implementation of our algorithm, the processing time for the interferograms with 850x850 pixels is around 5.1s. Measurement errors caused by several factors are analyzed, including wavelength-tuning error, frequency order error, cavity length error, and average thickness error. The experimental result on a rectangular transparent plate further verifies the effectiveness of our algorithm.

关键词： Interferometry wavelength-tuning fitting algorithm non-linear least-squares error analysis

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Technical Note: In silico and experimental evaluation of two leaf-fitting algorithms for MLC tracking based on exposure error and plan complexity

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MEDICAL PHYSICS 2019年第4期46卷 1814-1820页

作者： Caillet, Vincent O'Brien, Ricky Moore, Douglas Poulsen, Per Pommer, Tobias Colvill, Emma Sawant, Amit Booth, Jeremy Keall, Paul Northern Sydney Canc Ctr Sydney NSW Australia Univ Sydney Sydney Med Sch ACRF Image X Inst Sydney NSW Australia Arizona State Univ Ctr Fundamental Concepts Sci Tempe AZ USA Aarhus Univ Aarhus Denmark Karolinska Univ Hosp Unit Radiotherapy Phys & Engn Solna Sweden Univ Maryland Sch Med Dept Radiat Oncol Baltimore MD 21201 USA

PurposeMultileaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work was to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories. MethodsTo test the algorithms, both in silico and phantom experiments were performed. The phantom experiments were performed on a Trilogy Varian linac and a HexaMotion programmable motion platform. High and low modulation VMAT plans for lung and prostate cancer cases were used along with eight patient-measured organ-specific trajectories. For both MLC leaf-fitting algorithms, the plans were run with their corresponding patient trajectories. To compare algorithms, the average exposure errors, i.e., the difference in shape between ideal and fitted MLC leaves by the algorithm, plan complexity and system latency of each experiment were calculated. ResultsComparison of exposure errors for the in silico and phantom experiments showed minor differences between the two algorithms. The average exposure errors for in silico experiments with low/high plan complexity were 0.66/0.88cm(2) for direct optimization and 0.66/0.88cm(2) for piecewise optimization, respectively. The average exposure errors for the phantom experiments with low/high plan complexity were 0.73/1.02cm(2) for direct and 0.73/1.02cm(2) for piecewise optimization, respectively. The measured latency for the direct optimization was 22610ms and for the piecewise algorithm was 228 +/- 10ms. In silico and phantom exposure errors quantified for each treatment plan demonstrated that the exposure errors from the high plan complexity (0.96cm(2) mean, 2.88cm(2) 95% percentile) were all significantly different from the low plan complexity (0.70cm(2) mean, 2.18cm(2) 95% percentile) (P<0.001, two-tailed, Mann-Whitney statistical test). Conclusio

关键词： fitting algorithm MLC tracking radiotherapy real-time

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Line Measurement of Multi-Beam Sounding System Based on Annealing algorithm

Line Measurement of Multi-Beam Sounding System Based on Anne...

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2023 IEEE International Conference on Electrical, Automation and Computer Engineering, ICEACE 2023

作者： Yan, Xiaochen Lv, Lingfeng Xi, Rui Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (纸本)9798350309614

For a group of parallel survey lines with sloping sea floor at a certain Angle to the horizontal plane, the total path of the route is different when the Angle projected by the normal direction of the slope changes. This paper studies the shortest path when the value of the Angle is taken. The possible interval of the shortest path is calculated by the set of all possible obtained Angle values through certain traversal calculation method, and then the trend of path change is analyzed by fitting calculation method, and the Angle value of the shortest path is analyzed by annealing algorithm. After several studies to eliminate errors, it is found that the path is shortest when the direction of the measured line is perpendicular to the normal projection. © 2023 IEEE.

关键词： angle set annealing algorithm fitting algorithm shortest path traversal algorithm

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Axial peak extraction in the measurement of subsurface structures with annular illumination confocal microscopy

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SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES 2024年第3期12卷 035030-035030页

作者： Jiang, Yong Liu, Chenguang Zou, Chongliang Liu, Jian Harbin Inst ofTechnol Adv Microscopy & Instrumentat Res Ctr Sch Instrumentat Sci & Engn Harbin 150001 Peoples R China

Three-dimensional dark-field confocal microscopy (DFCM) using annular illumination and complementary detection apertures is capable of detecting subsurface defects in ultra-precision optical components. In this study, a DFCM tuning algorithm for large apertures is proposed based on the sinc2 tuning model. This algorithm provides a reliable and theoretically accurate method for extracting the axial position during the measurement of subsurface defects. The rationality and accuracy of this method are verified through simulations and experimental results.

关键词： dark-field confocal microscopy axial peak extraction fitting algorithm

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Fast and accurate position verification algorithms for dose delivery system in proton therapy scanning nozzle system

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2021年 986卷 164719-164719页

作者： Lin, Yinjie Tan, Ping Guo, Huidong Zhang, Lige Lei, Hao Yu, Yecheng Li, Xingyu Huazhong Univ Sci & Technol State Key Lab Adv Electromagnet Engn & Technol Sch Elect & Elect Engn Wuhan 430074 Hubei Peoples R China

The spot position and size of a proton beam are critical parameters in the scanning dose delivery system. They need to be validated efficiently and accurately. But the traditional methods work poorly in some non-ideal cases. In this study, we develop effective means for the position verification algorithm, including the student's t distribution fitting algorithm, the Slope method, as well as the improved Gaussian fitting algorithm. And we verify the accuracy of them experimentally. That is several times higher than the one of the traditional fitting algorithms. The root mean square error (RMSE) of the improved Gaussian fitting algorithm is less than 0.2 mm as the signal-to-noise ratio (SNR) is higher than 30 dB even when a damaged strip exists around the beam spot. Furthermore, we implement the proposed Gaussian fitting arithmetic and the Slope method in Field Programmable Gate Arrays (FPGA) to test their efficiency. If the clock frequency of the chip with enough calculation resources is higher than 10 MHz, the computing time can be less than 6 mu s and 4 mu s, respectively. Finally, we conduct a simulation experiment. The result shows that RMSE of the proposed three methods are all less than 0.3 mm as the SNR is around 25 dB.

关键词： Proton therapy Ionization chamber fitting algorithm

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Random changepoint segmented regression with smooth transition

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STATISTICAL METHODS IN MEDICAL RESEARCH 2021年第3期30卷 643-654页

作者： Singer, Julio M. Rocha, Francisco M. M. Pedroso-de-Lima, Antonio Carlos Silva, Giovani L. Coatti, Giuliana C. Zatz, Mayana Univ Sao Paulo Dept Estat Rua Matao 1010 BR-05508090 Sao Paulo SP Brazil Univ Fed Sao Paulo Dept Multidisciplinar Escola Paulista Polit Econ & Negocios Sao Paulo SP Brazil Univ Lisbon Dept Matemat IST Lisbon Portugal Univ Lisbon CEAUL Lisbon Portugal Univ Sao Paulo Inst Biociencias Sao Paulo Brazil

We consider random changepoint segmented regression models to analyse data from a study conducted to verify whether treatment with stem cells may delay the onset of a symptom of amyotrophic lateral sclerosis in genetically modified mice. The proposed models capture the biological aspects of the data, accommodating a smooth transition between the periods with and without symptoms. An additional changepoint is considered to avoid negative predicted responses. Given the nonlinear nature of the model, we propose an algorithm to estimate the fixed parameters and to predict the random effects by fitting linear mixed models iteratively via standard software. We compare the variances obtained in the final step with bootstrapped and robust ones.

关键词： Amyotrophic lateral sclerosis fitting algorithm mixed models random effects

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Improvement and Performance Evaluation of a Dual-Probe Heat Pulse Distributed Temperature Sensing Method Used for Soil Moisture Estimation

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SENSORS 2022年第19期22卷 7592页

作者： Yao, Jun-Cheng Shi, Bin Liu, Jie Sun, Meng-Ya Fang, Ke Yao, Jian Gu, Kai Zhang, Wei Zhang, Ji-Wen Nanjing Univ Sch Earth Sci & Engn Nanjing 210023 Peoples R China Hohai Univ Sch Earth Sci & Engn Nanjing 210098 Peoples R China Jiangsu Prov Engn Invest & Res Inst Co Ltd Yangzhou 225002 Jiangsu Peoples R China China JK Inst Engn Invest & Design Co Ltd Xian 710043 Peoples R China

Large-scale measurements of soil moisture play a critical role in many fields, such as agriculture, hydrology, and engineering. The distributed temperature sensing (DTS) technology, based on a dual-probe heat pulse (DPHP), is a novel approach to realizing large-scale soil moisture estimation. However, the application of the method is limited by the complex optical cable layout, calculation algorithm, and lack of standardized heating strategy. In this paper, an improved DPHP-DTS method considering the soil bulk density was proposed. The measurement accuracy of the DPHP-DTS method under different heating strategies was studied in laboratory experiments, and its long-term stability in regard to the monitoring of soil moisture during natural evaporation in different soils was tested. The results show that the improved DPHP-DTS method can accurately measure the soil moisture, and the fitting algorithm can reduce the error caused by the accuracy of the DTS temperature measurement under the low-power heating strategy. Its measurement accuracy increases with the increase in the heating strength and duration. In addition, the improved DPHP-DTS method can describe soil evaporation in both sand and loess with good reliability and stability.

关键词： soil moisture estimation dual-probe heat pulse (DPHP) distributed temperature sensing (DTS) heating strategy fitting algorithm

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IVIM MRI - Evolution from DWI, Observations, Challenges and Relevance of pre and post processing phases 5

IVIM MRI - Evolution from DWI, Observations, Challenges and ...

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5th International Conference on Electrical, Electronics, Communication, Computer Technologies and Optimization Techniques (ICEECCOT)

作者： Raju, Jini Amma, Ushadevi C. John, Ansamma APJ Abdul Kalam Technol Univ Thangal Kunju Musaliar Coll Engn Dept Comp Sci & Engn Kollam Kerala India Amrita Vishwa Vidhyapeetham Dept Elect & Commun Engn Amritapuri Campus Kollam Kerala India

ISBN: (纸本)9781665432726

Intravoxel Incoherent Motion Magnetic Resonance Imaging(IVIM MRI) is a quantitative, non invasive imaging technique that exploits perfusion and diffusion properties of tissues. Even though IVIM has grown in popularity in recent years, there is still a lot of research being done in the field, from image acquisition to disease diagnosis. This paper explores various challenges faced by researchers as well as clinicians during the IVIM image acquisition and postprocessing phases, through experimental analysis. The numerous issues associated with image acquisition phase are the properly fixing up of b value count, absolute b values, threshold b value and the highest achievable b value. The selection of image formats and correlation between slices in IVIM MRI images are other significant challenges during the image acquisition phase. The selection of appropriate fitting algorithm, for the estimation of IVIM parameters, is the major challenge in the post processing phase which is addressed by selecting an algorithm based on the quality off, D and D* maps generated. Since IVIM is in its infancy stage, the lack of real IVIM images is one of the major hurdles in IVIM research and hence simulated data is also used in addition to the available real dataset.

关键词： Diffusion Weighted Imaging Intravoxel Incoherent Motion Imaging fitting algorithm Image Postprocessing

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Experimentally study of dynamic pressure distribution and oil film forces in journal bearing using ElectroMechanical Film sensor array

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2020年第4期234卷 903-913页

作者： Chen, Changmin Jing, Jianping Cong, Jiqing Ji, Chao Shanghai Jiao Tong Univ State Key Lab Mech Syst & Vibrat Dongchuan Rd 800 Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Gas Turbine Res Inst Shanghai Peoples R China Shanghai Jiao Tong Univ Shock & Noise Lab Fundamental Sci Vibrat Shanghai Peoples R China

The acquisition of the oil film pressure and forces on the bearing pads through experimentation is crucial to understanding the characteristics of journal bearing. Lots of efforts had been taken in film pressure measurement, and the pressure was obtained at specified position on the bearing pads. However, due to the space and structure constraint, merely very limited number of the point pressure can be obtained with traditional sensors and acquiring the detail pressure field on whole bearing pad surface is still an open challenge. In this paper, a method based on thin-film sensors technique is proposed and employed to measure the pressure distribution and oil film forces of journal bearings. The measurement is conducted on a cylindrical journal bearing with two axial grooves, and ElectroMechanical Film sensor arrays are designed and laid on the surface of the bearing pads. The oil film pressure is acquired at up to 32 measurement points in total along the bearing pads in both circumference and axial directions. The pressure distribution in a wide rotation speed range is obtained successfully by using fitting algorithm. Furthermore, the oil film forces on horizon and vertical direction are obtained through the integration of the measured pressure filed. The test results prove that it is feasible to measure the oil pressure filed of journal bearings using ElectroMechanical Film piezo-film sensor array.

关键词： ElectroMechanical Film sensor array pressure distribution oil film force journal bearing fitting algorithm

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Study of the Curve fitting algorithm for NC Machining Graphics

Study of the Curve Fitting Algorithm for NC Machining Graphi...

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8th International Conference on Computer Science and Education (ICCSE)

作者： Xu Jishui Zhang Zipeng Wang Shuqing Wuhan Univ Sch Power & Mech Engn Wuhan 430072 Peoples R China

ISBN: (纸本)9781467344630;9781467344647

In the process of NC machining, the precise computation of machining graphical path is the key to guarantee machining precision. In curve fitting, it is difficult to fit curve just only using straight line. The combining both arc and line may get good fitting effect in fitting curve. But it leads to complicated calculation in fitting. Aiming at this problem, multi-dimensional fuzzy reasoning algorithm is proposed in this paper to optimize the calculation process and improve the fitting curve speed and accuracy. The designed multidimensional fuzzy inference algorithm makes the computation of the curve fitting simplicity and preciseness when the model structure is used in programming. Test results show that the designed way can well approximate the original graphics and well optimize the number of segment in the fitting process.

关键词： curve fitting NC machining graphics fuzzy reasoning fitting algorithm

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