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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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Trace data characterization and fitting for Markov modeling

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PERFORMANCE EVALUATION 2010年第2期67卷 61-79页

作者： Casale, Giuliano Zhang, Eddy Z. Smirni, Evgenia SAP Res CEC Belfast Newtownabbey North Ireland Coll William & Mary Dept Comp Sci Williamsburg VA 23185 USA

We propose a trace fitting algorithm for Markovian Arrival Processes (MAPs) that can capture statistics of any order of interarrival times between measured events. By studying real traffic and workload traces often used in performance evaluation studies, we show that matching higher order statistical properties, in addition to first and second order descriptors, results in increased queueing prediction accuracy with respect to algorithms that only match the mean, the coefficient of variation, and the autocorrelations of the trace. This result supports the approach of modeling traces by the interarrival time process instead of the counting process that is more frequently used in the literature. We proceed by first characterizing the general properties of MAPs using a spectral approach. Based on this result, we show how different MAPs can be combined together using Kronecker products to define a larger MAP with predefined properties of interarrival times. We then devise an algorithm that is based on this Kronecker composition and can accurately fit data traces. This MAP fitting algorithm uses nonlinear optimization that can be customized to fit an arbitrary number of moments and to meet the desired cost-accuracy tradeoff. Numerical results of the fitting algorithm on real data, such as the Bellcore Aug89 trace and a Seagate disk drive trace, indicate that the proposed fitting technique achieves increased prediction accuracy with respect to other state-of-the-art fitting methods. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Markovian arrival process fitting algorithm Time series modeling Temporal dependence Correlations

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Semiautomated building extraction based on CSG model-image fitting

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PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING 2003年第2期69卷 171-180页

作者： Tseng, YH Wang, SD Natl Cheng Kung Univ Dept Surveying Engn Tainan 701 Taiwan

Building extraction based on pre-established models has been recognized as a promising idea for acquiring 3D data for buildings from aerial images. This paper proposes a novel building extraction method developed from the concept of fitting CSG (Constructive Solid Geometry) primitives to aerial images. To be practicable, this method adopts a semiautomatic procedure, carrying out high-level tasks (building detection, model selection, and attribution) interactively by the operator and performing optimal model-image fitting automatically with a least-squares fitting algorithm. Buildings, represented by CSG models, can be reconstructed part by part after fitting each parameterized CSG primitive to the edge pixels of aerial images. Reconstructed building parts can then be combined using CSG Boolean set operators, Consequently, a building is represented by a CSG tree in which each node links two branches of combined parts. This paper demonstrates ten examples of building extraction from aerial photos taken at a scale of 1:5,000 and scanned at a pixel size of 25 mum. All of the tests were performed in the prototypal system implemented in a CAD-based environment cooperated with a number of specially designed programs. The process time for each primitive is about 20 seconds and the successful rate of model-image fitting was about 90 percent. Evaluated with some check points, the fitting accuracy was about 0.3 m horizontally and 1 m vertically. The test results are encouraging and promote the theory of model-based building extraction.

关键词： .Building Extraction least-squares model selection AERIAL IMAGES primitives Boolean Semiautomatic Model-Image fitting fitting algorithm CSG models edge pixels building parts

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Quadrilateral mesh fitting that preserves sharp features based on multi-normals for Laplacian energy

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JOURNAL OF COMPUTATIONAL DESIGN AND ENGINEERING 2014年第2期1卷 88-95页

作者： Imai, Yusuke Hiraoka, Hiroyuki Kawaharada, Hiroshi Chuo Univ Dept Precis Mech Bunkyo Ku 1-13-27 Kasuga Tokyo 1128551 Japan

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

关键词： CAD model Hexahedral mesh Sharp feature fitting algorithm Multi-normalvectors

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Development of fitting Program for Fully Implantable Middle Ear Hearing Device

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11th International Congress of the IUPESM/World Congress on Medical Physics and Biomedical Engineering

作者： Lee, Seung Hyun Lim, Hyung Gyu Jung, Eui Sung Kim, Min Woo An, Jinung Cho, Jin Ho Daegu Gyeongbuk Inst Sci & Technol Brain Robot Interact Lab Taegu South Korea Kyungpook Natl Univ Grad Sch Elect Engn & Comp Sci Taegu South Korea

ISBN: (纸本)9783642038907

A fully implantable middle ear hearing device (F-IMEHD) has been investigated in Korea. Generally, F-IMEHD is implanted under the skin at human temporal bone and it uses implantable microphone and vibrating transducer. Therefore, F-IMEHD must require a different fitting process from conventional hearing aids. In this paper, a fitting program for the F-IMEHD has been developed using LabVIEW. We calculate proper fitting parameters based on FIG6 fitting rule. And also, it takes account of frequency characteristics of F-IMEHD's components. Through experimental results, it can be confirmed that the proposed fitting program is suitable to F-IMEHD.

关键词： F-IMEHD hearing fitting fitting algorithm

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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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Optimizing discrete point sample patterns and measurement data analysis on internal cylindrical surfaces with systematic form deviations

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PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY 2002年第1期26卷 105-121页

作者： Summerhays, KD Henke, RP Baldwin, JM Cassou, RM Brown, CW Univ San Francisco Harney Sci Ctr San Francisco CA 94117 USA Micro Vu Inc Windsor CA 95492 USA Sandia Natl Labs Livermore CA 94551 USA Honeywell Fed Mfg & Technol Kansas City MO 64141 USA MetroSage LLC Volcano CA 95689 USA

Selection of an appropriate sampling strategy and of the correct fitting algorithm are two of the key issues in the practice of modem coordinate metrology. A recent report described the development of new techniques for modeling the form errors of machined part features and illustrated their use in identifying and understanding the relation of form errors to machining process variables. In this report, these mathematical tools are further developed and applied for the determination of optimum, reasonably-sized probing patterns for measurement under time and economic constraints. The focus of the work reported here is on full internal cylindrical surfaces. The technique is, however, of general utility and can be employed with any nominal feature geometry. Its application does, in many cases, produce significant improvements in the uncertainty of derived geometric dimensioning and tolerancing parameters with modest or no increase in measurement time. In contrast to most work on these problems, extensive use is made of process-dependent information in selection of sampling protocol and data analysis method. Since the method begins with an understanding of the form errors introduced into the part by the particular manufacturing regime, at least partial benefit can be seen even when the sample pattern optimization is employed in conjunction with commercial, off-the-shelf CMM control and data analysis software. (C) 2001 Elsevier Science Inc. All rights reserved.

关键词： coordinate measuring machine sampling plan fitting algorithm cylinder form error principal component analysis Chebyshev polynomial Fourier series eigen shapes least squares minimum zone maximum inscribed cylinder

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Development of a new method of the analysis mossbauer spectra of systems with nuclear heterogeneity

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HYPERFINE INTERACTIONS 2006年第1-3期167卷 887-892页

作者： Pikulev, A. I. Semenkin, V. A. Milder, O. B. Novikov, E. G. Ural State Tech Univ Fac Expt Phys Ekaterinburg 620002 Mira Russia

At present there are two main rival fitting approaches to mossbauer spectra: restoration of hyperfine parameter distribution and discrete deconvolution one. Use of the parallel circuit of processing in which computing procedure the exchange of the calculated values between continuous and discrete algorithms is used for the first time is offered.

关键词： mossbauer spectroscopy fitting algorithm

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Optimal design of FBG flexible sensor for high-precision monitoring of three-dimensional deformation of power transmission line tower foundation

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ENERGY REPORTS 2023年 9卷 46-54页

作者： Tian, Changbin Ma, Xin Ma, Xiangxue Peng, Bo Shandong Jianzhu Univ Sch Informat & Elect Engn 1000 Fengming Rd Jinan 250101 Peoples R China

During the operation of the power transmission line tower foundation, uneven settlement and horizontal sliding were formed due to the damage of the local environment or external force. It is the most direct and effective way to realize the transformation from "passive response " to "active prevention and control " by real-time and long-term monitoring of the tower foundation and providing automatic early warning. In this paper, based on FBG (fiber Bragg grating) sensing technology, a FBG flexible sensor with temperature self-compensation characteristic was developed, which can be used for real-time monitoring of three-dimensional deformation field of tower foundation. Based on the strain information measured by the sensor, a coordinate transformation fitting algorithm was applied to reconstruct the deformation field of the tower foundation. To improve the displacement sensing precision of the flexible sensor, the influence of the length of the cemented layer and the groove radius on the strain transfer coefficient was analyzed, and the orthogonal curvature obtained by the sensing point was corrected by cubic spline interpolation. In the displacement sensing experiment, the mean absolute errors along the x-axis direction after interpolation correction were 1.84 mm (Type 1), 1.52 mm (Type 2) and 1.96 mm (Type 3), respectively;the mean absolute errors along the y-axis direction were 1.64 mm (Type 1), 2.34 mm (Type 2) and 1.21 mm (Type 3), respectively. After interpolation correction, the maximum absolute error percentages of the measuring points along the x-axis were 9.62% (Type 1), 9.01% (Type2) and 10.23% (Type 3);the maximum absolute error percentages along the y-axis were 10.44% (Type 1), 9.53% (Type2) and 9.43% (Type 3). Therefore, the designed FBG flexible sensor can be competent for the task of monitoring the three-dimensional deformation field of the tower foundation, which has important significance and application promotion value.(c) 2022 The Author(s). Publi

关键词： Deformation monitoring FBG flexible sensor fitting algorithm Sensing precision Cubic spline interpolation

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Data analysis for surface plasmon resonance sensors using dynamic baseline algorithm

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SENSORS AND ACTUATORS B-CHEMICAL 2005年第2期106卷 796-802页

作者： Thirstrup, C Zong, W Vir AS Vir Biosensor DK-2630 Taatstrup Denmark

Needs of accurate and robust responses from surface plasmon resonance (SPR) sensor systems put high requirements to the data analysis methods used. The output of an SPR sensor comprises data of reflected light intensity as function of either wavelength or angle of incidence (SPR curve). As reported in the literature, commonly used methods for analysing the SPR curve are polynomial curve fitting methods and the centroid method. These methods have their drawbacks in either being sensitive to correlated noise or drift from the light source, or generating high noise on the SPR response. We propose a modified analysis algorithm, where a baseline for selection of data from the SPR curve is adjusted dynamically according to a pre-defined ratio between the areas of the SPR curve below and above the baseline. It is shown in a mathematical model, numerical simulations as well as in experiments that the proposed dynamic baseline algorithm is insensitive to optical power correlated noise/drift. The algorithm is mathematically simple and it can be readily combined with commonly used data analysis methods. (c) 2004 Published by Elsevier B.V.

关键词： surface plasmon biosensor data analysis fitting algorithm

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