Articles de revues sur le sujet « Simulation and reconstruction »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Simulation and reconstruction.
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Simulation and reconstruction ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Friduss, Michael, Paul Dagum, Alexander Mandych et Angelo Reppucci. « Forehead Flap in Nasal Reconstruction ». Otolaryngology–Head and Neck Surgery 113, no 6 (décembre 1995) : 740–47. http://dx.doi.org/10.1016/s0194-59989570014-5.
Texte intégralRésumé :
We establish criteria for aesthetic forehead flap reconstructions and evaluate the effect of mathematical models and computer simulation of the operation in preoperative and perioperative planning. We study a case series of 13 patients in an academic tertiary referral medical center. Most patients had nasal defects after Mohs' surgery for tumor ablation. Patients were followed up for 2 years after reconstructive surgery. Three patients underwent midline forehead flap nasal reconstructions, and 10 patients underwent paramedian forehead flap nasal reconstructions. We used patient satisfaction and physician evaluation of aesthetic form and function restoration as the main outcome measures. There were no major complications. Minor complications included short-term pincushioning in all patients, scar contracture that resolved after 8 months in one patient, and forehead necrosis after primary closure of the upper forehead in one patient. Computer simulation correlated two-dimension flap design to the transposition process. We conclude that the forehead flap is the optimal reconstructive modality for resurfacing large nasal defects. The paramedian forehead flap is superior to the midline forehead flap for nasal reconstruction, especially for distal tip reconstructions. Mathematical models and computer simulation of the reconstructive procedure that relate the two-dimensional flap design to the transposition process reveal subtle geometric relationships of the flap transposition that facilitate the design of the optimal flap for reconstruction.
2
González-Rouco, J. F., H. Beltrami, E. Zorita et M. B. Stevens. « Borehole climatology : a discussion based on contributions from climate modeling ». Climate of the Past 5, no 1 (19 mars 2009) : 97–127. http://dx.doi.org/10.5194/cp-5-97-2009.
Texte intégralRésumé :
Abstract. Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments.
3
González-Rouco, J. F., H. Beltrami, E. Zorita et M. B. Stevens. « Borehole climatology : a discussion based on contributions from climate modeling ». Climate of the Past Discussions 4, no 1 (21 janvier 2008) : 1–80. http://dx.doi.org/10.5194/cpd-4-1-2008.
Texte intégralRésumé :
Abstract. Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments.
4
Tran, Khanh Linh, Matthew Lee Mong, James Scott Durham et Eitan Prisman. « Benefits of Patient-Specific Reconstruction Plates in Mandibular Reconstruction Surgical Simulation and Resident Education ». Journal of Clinical Medicine 11, no 18 (9 septembre 2022) : 5306. http://dx.doi.org/10.3390/jcm11185306.
Texte intégralRésumé :
Poorly contoured mandibular reconstruction plates are associated with postoperative complications. Recently, a technique emerged whereby preoperative patient-specific reconstructive plates (PSRP) are developed in the hopes of eliminating errors in the plate-bending process. This study’s objective is to determine if reconstructions performed with PSRP are more accurate than manually contoured plates. Ten Otolaryngology residents each performed two ex vivo mandibular reconstructions, first using a PSRP followed by a manually contoured plate. Reconstruction time, CT scans, and accuracy measurements were collected. Paired Student’s t-test was performed. There was a significant difference between reconstructions with PSRP and manually contoured plates in: plate-mandible distance (0.39 ± 0.21 vs. 0.75 ± 0.31 mm, p = 0.0128), inter-fibular segment gap (0.90 ± 0.32 vs. 2.24 ± 1.03 mm, p = 0.0095), mandible-fibula gap (1.02 ± 0.39 vs. 2.87 ± 2.38 mm, p = 0.0260), average reconstruction deviation (1.11 ± 0.32 vs. 1.67 ± 0.47 mm, p = 0.0228), mandibular angle width difference (5.13 ± 4.32 vs. 11.79 ± 4.27 mm, p = 0.0221), and reconstruction time (16.67 ± 4.18 vs. 33.78 ± 8.45 min, p = 0.0006). Lower plate-mandible distance has been demonstrated to correlate with decreased plate extrusion rates. Similarly, improved bony apposition promotes bony union. PSRP appears to provide a more accurate scaffold to guide the surgeons in assembling donor bone segments, which could potentially improve patient outcome and reduce surgical time. Additionally, in-house PSRP can serve as a low-cost surgical simulation tool for resident education.
5
Ljungqvist, Fredrik Charpentier, Qiong Zhang, Gudrun Brattström, Paul J. Krusic, Andrea Seim, Qiang Li, Qiang Zhang et Anders Moberg. « Centennial-Scale Temperature Change in Last Millennium Simulations and Proxy-Based Reconstructions ». Journal of Climate 32, no 9 (12 avril 2019) : 2441–82. http://dx.doi.org/10.1175/jcli-d-18-0525.1.
Texte intégralRésumé :
AbstractSystematic comparisons of proxy-based reconstructions and climate model simulations of past millennium temperature variability offer insights into climate sensitivity and feedback mechanisms, besides allowing model evaluation independently from the period covered by instrumental data. Such simulation–reconstruction comparisons can help to distinguish more skillful models from less skillful ones, which may subsequently help to develop more reliable future projections. This study evaluates the low-frequency simulation–reconstruction agreement within the past millennium through assessing the amplitude of temperature change between the Medieval Climate Anomaly (here, 950–1250 CE) and the Little Ice Age (here, 1450–1850 CE) in PMIP3 model simulations compared to proxy-based local and continental-scale reconstructions. The simulations consistently show a smaller temperature change than the reconstructions for most regions in the Northern Hemisphere, but not in the Southern Hemisphere, as well as a partly different spatial pattern. A cost function analysis assesses how well the various simulations agree with reconstructions. Disregarding spatial correlation, significant differences are seen in the agreement with the local temperature reconstructions between groups of models, but insignificant differences are noted when compared to continental-scale reconstructions. This result points toward a limited possibility to “rank” models by means of their low-frequency temperature variability alone. The systematically lower amplitude of simulated versus reconstructed temperature change indicates either too-small simulated internal variability or that the analyzed models lack some critical forcing or have missing or too-weak feedback mechanisms. We hypothesize that too-cold initial ocean conditions in the models—in combination with too-weak internal variability and slow feedbacks over longer time scales—could account for much of the simulation–reconstruction disagreement.
6
Xu, Han, Cynthia Changxin Wang, Xuesong Shen et Sisi Zlatanova. « 3D Tree Reconstruction in Support of Urban Microclimate Simulation : A Comprehensive Literature Review ». Buildings 11, no 9 (17 septembre 2021) : 417. http://dx.doi.org/10.3390/buildings11090417.
Texte intégralRésumé :
The negative climate change induced by rapid urbanization has become a global environmental issue. Numerous studies have been devoted to microclimate regulation functions performed by urban vegetation. Digital city information modeling provides a powerful tool for various simulations and data analytics for the sustainable development of urban areas. However, the method reconstructing urban trees is still in its early stage compared to the relatively mature building modeling. Most prior studies on tree reconstruction focused on retrieving geometric features, while other factors related to urban microclimate simulation were rarely addressed. This paper presents a comprehensive literature review and in-depth analysis covering two distinct research directions in relation to urban microclimate simulation. The first one is set on the identification of key factors related to trees’ impact on urban microclimate. The second one is dedicated to approaches for three-dimensional (3D) tree reconstruction. Based on the findings, the paper identifies information including trees’ geometric, physiological characteristics and relation to the surroundings required for 3D tree reconstruction in the context of urban microclimate simulation, and further assesses the potential of the 3D tree reconstruction approaches to accommodate these pieces of information. An appropriate 3D tree reconstruction approach, which allows for the supply of the required information for urban microclimate simulation, is recommended.
7
Ballarotta, M., K. Döös, P. Lundberg, L. Brodeau et J. Brandefelt. « A Last Glacial Maximum World-Ocean simulation at eddy-permitting resolution – Part 2 : Confronting the paleo-proxy data ». Climate of the Past Discussions 9, no 1 (18 janvier 2013) : 329–50. http://dx.doi.org/10.5194/cpd-9-329-2013.
Texte intégralRésumé :
Abstract. Previous investigations concerning the design of an eddy-permitting LGM oceanic simulation are here extended with focus on whether this type of simulation is capable of improving the numerical results with regard to the available paleo-proxy reconstructions. Consequently, an eddy-permitting and two coarse-grid simulations of the same LGM period are confronted with a dataset from the Multiproxy Approach for the Reconstruction of the Glacial Ocean Sea Surface Temperatures (MARGO SSTs) and a number of sea-ice reconstructions. From a statistical analysis it was found that the eddy-permitting simulation does not significantly improve the SST representation with regard to the paleo-reconstructions. The western boundary currents are better resolved in the high-resolution experiment than in the coarse simulations, but, although these more detailed SST structures yield a locally improved consistency between modelled predictions and proxies, they do not contribute significantly to the global statistical score. As in the majority of the PMIP2 simulations, the modelled sea-ice conditions are still inconsistent with the paleo-reconstructions, probably due to the choice of the model equilibrium.
8
Yang, Xiao Long, Ping Li, Tao Lv et Xue Hua Liao. « Traffic Accident Reconstruction Technology Research ». Advanced Materials Research 756-759 (septembre 2013) : 946–51. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.946.
Texte intégralRésumé :
Based on the virtual simulation theory, we used three-dimensional modeling software to build modeling road facilities (vehicles, trees, street lights, etc.) for simulating the accident environment, and by using OpenGL technology, achieved reading, displaying and controlling the three-dimensional models. This dynamically realized the three-dimensional animated simulation of vehicle movement. Simultaneously we have calculated in progress the simulation of vehicle crash with the basic theory of automobile collision, vehicle collision model and the law of conservation of energy and momentum. Finally, we constructed a flexible platform for the simulation experiment. The platform is enabling to add and update road, trees, street lamps and house on the simulation environment dynamically, and has ability to analysis the traffic accident. This could give an assistant to the handling traffic accidents.
9
He, Jing. « Multimedia Vision Improvement and Simulation in Consideration of Virtual Reality Reconstruction Algorithms ». Journal of Electrical and Computer Engineering 2022 (12 mai 2022) : 1–10. http://dx.doi.org/10.1155/2022/4968588.
Texte intégralRésumé :
Due to the large noise and many discrete points of the image in the traditional image reconstruction process, the reconstruction quality of the image deviates greatly from the actual target. In this study, the virtual reality reconstruction algorithm is applied to multimedia vision, the virtual reality image is corrected by using the binocular offset positioning method, the denoising process is performed in the image reconstruction process, and the high-pass filter matrix is used to improve the image reproduction. At the same time, the three-dimensional reconstruction algorithm is used to perform correlation retrieval, the ensemble point set and the discrete point set are obtained, the maximum and minimum reconstruction degree areas are clarified, and the deviation reconstruction and peak relocation can be performed. Finally, the experimental test results show that the algorithm in this study can enhance the authenticity of image reconstruction, improve the accuracy of image corner detection, and effectively reduce the noise interference in the process of reconstructing the image.
10
Qi, Yusheng, Wenting Xiao et Dick K. P. Yue. « Phase-Resolved Wave Field Simulation Calibration of Sea Surface Reconstruction Using Noncoherent Marine Radar ». Journal of Atmospheric and Oceanic Technology 33, no 6 (juin 2016) : 1135–49. http://dx.doi.org/10.1175/jtech-d-15-0130.1.
Texte intégralRésumé :
AbstractThe possibility of reconstructing sea surface wave fields from a noncoherent X-band marine radar return has much potential for maritime operations and ocean engineering. The existing reconstruction method extracts the signal associated with gravity waves that satisfy the dispersion relationship. The process involves parameters related to how the radar signal is modulated by waves of different lengths, propagation directions, amplitudes, and phases. In the absence of independent wave measurements, these reconstruction parameters cannot be rationally adjusted according to wave field conditions, and the predictions are generally of uneven accuracy and reliability. A new reconstruction method based on concurrent phase-resolved wave field simulations is proposed. By maximizing the correlation between the reconstructed and simulated wave fields over time, optimal values of the reconstruction parameters are obtained that are found to vary appreciably with the wave field properties and with the location and size of the subdomain being sensed and reconstructed. With this phase-resolved simulation calibrated (PRSC) approach, the correlation between the evolving reconstructed wave field and that based on phase-resolved simulation, which measures the consistency and fidelity of the reconstruction, is improved significantly (by up to a factor of 2) and is obtained in a substantially broader range of sea states compared to existing methods.
11
Wu, Wen Zheng, Ji Zhao, Lei Zhang, Nan Feng et David W. Rosen. « Customized Titanium Plate Virtual Design and Deformation Simulation Analysis of Human Lateral Mandible Defect ». Applied Mechanics and Materials 157-158 (février 2012) : 227–30. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.227.
Texte intégralRésumé :
Aiming to improve the defect mandible reconstruction operation success rate, the original mandible and fibular 3D model were modeling separately. According to the patient’s virtual reconstruction mandible 3D model, the mandible customized virtual ti-plate was designed and modeling. Through comparing the deformation simulation analysis of reconstructive mandible, the maximum deformation occurred near the mandible midline. There was little deformation at bilateral mandible ramus posterior. As the loading on the reconstructive mandible increasing, the maximum deformation near the mandible midline was increasing. According to the customized titanium plate virtual design and deformation simulation analysis of human lateral mandible defect before operation, the simulation could predict the mandible maximum deformation position after the surgery. The doctors could improve the operation precision of mandible reconstruction and probability of success significantly.
12
Idris, Sherif, Heather Logan, Paul Tabet, Martin Osswald, Suresh Nayar et Hadi Seikaly. « The Accuracy of 3D Surgical Design and Simulation in Prefabricated Fibula Free Flaps for Jaw Reconstruction ». Journal of Personalized Medicine 12, no 11 (26 octobre 2022) : 1766. http://dx.doi.org/10.3390/jpm12111766.
Texte intégralRésumé :
The ideal jaw reconstruction involves the restoration and maintenance of jaw continuity, jaw relations, joint alignment, and facial contour, and, most importantly, dental occlusal reconstruction. One of the essential requirements of achieving a consistent functional outcome is to place the bony reconstruction in the correct three-dimensional position as it relates to the other jaw segments and dentition. A protocol of occlusion-driven reconstruction of prefabricated fibular free flaps that are customized to the patient with surgical design and simulation (SDS)-planned osseointegrated implant installation was developed by our institution. This innovation introduced significant flexibility and efficiency to jaw reconstructions, but functional and cosmetic outcomes were dependent on the accuracy of the final reconstructions when compared to the SDS plan. The purpose of this study was to examine the accuracy of the SDS-planned fibular flap prefabrication in a cohort of patients undergoing jaw reconstruction. All patients that had undergone primary jaw reconstruction with prefabricated fibular free flaps were reviewed. The primary outcome of this study was the accuracy of the postoperative implant positions as compared to the SDS plan. A total of 23 implants were included in the analysis. All flaps survived, there was no implant loss postoperatively, and all the patients underwent all stages of the reconstruction. SDS planning of fibular flap prefabrication resulted in better than 2 mm accuracy of osteointegrated implant placement in a cohort of patients undergoing jaw reconstruction. This accuracy could potentially result in improved functional and cosmetic outcomes.
13
Yang, C., J. Chen, J. Q. Li et W. F. Xue. « Simulation and experimental investigations for the patch near-field acoustical holography ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 222, no 6 (1 juin 2008) : 945–53. http://dx.doi.org/10.1243/09544062jmes727.
Texte intégralRésumé :
In order to reconstruct the sound field, the fast Fourier transform (FFT)-based near-field acoustical holography (NAH) demands that the measurement surface must extend to a region where the sound pressure decreases to a low level. This method is unfit for reconstructing the partial sound field in which the measurement aperture size is limited either by physical necessity or as a way of reducing the measurement cost. Statistically optimal NAH (SONAH) performs plane-to-plane calculations directly in the spatial domain, avoids all errors occurred in the FFT-based NAH and significantly increases the accuracy of the reconstruction of the partial sound field. In the present work, combined with the different regularization methods, SONAH is performed for reconstructing the partial sound field. The errors over the central and the peripheral sections of the reconstruction area are researched separately. Simulations and experiments show that SONAH is successful in reconstructing the partial sound field and the errors over the central sections are smaller than that over the peripheral sections. Experiments demonstrate that Tikhonov regularization in conjunction with Engl's criterion is suitable for the reconstruction of the practical sound field.
14
Bothe, Oliver, et Eduardo Zorita. « Proxy surrogate reconstructions for Europe and the estimation of their uncertainties ». Climate of the Past 16, no 1 (18 février 2020) : 341–69. http://dx.doi.org/10.5194/cp-16-341-2020.
Texte intégralRésumé :
Abstract. Combining proxy information and climate model simulations reconciles these sources of information about past climates. This, in turn, strengthens our understanding of past climatic changes. The analogue or proxy surrogate reconstruction method is a computationally cheap data assimilation approach, which searches in a pool of simulated climate states the best fit to proxy data. We use the approach to reconstruct European summer mean temperature from the 13th century until present using the Euro 2k set of proxy records and a pool of global climate simulation output fields. Our focus is on quantifying the uncertainty of the reconstruction, because previous applications of the analogue method rarely provided uncertainty ranges. We show several ways of estimating reconstruction uncertainty for the analogue method, which take into account the non-climate part of the variability in each proxy record. In general, our reconstruction agrees well at multi-decadal timescales with the Euro 2k reconstruction, which was conducted with two different statistical methods and no information from model simulations. In both methodological approaches, the decades around the year 1600 CE were the coldest. However, the approaches disagree on the warmest pre-industrial periods. The reconstructions from the analogue method also represent the local variations of the observed proxies. The diverse uncertainty estimates obtained from our analogue approaches can be locally larger or smaller than the estimates from the Euro 2k effort. Local uncertainties of the temperature reconstructions tend to be large in areas that are poorly covered by the proxy records. Uncertainties highlight the ambiguity of field-based reconstructions constrained by a limited set of proxies.
15
Wang, Haitao, Lin Zhang, Yakun Wang, Yaocheng Nie et Xiangyang Zeng. « Global Sound Field Reconstruction in the Room Environment Based on Inverse Wave-Based Simulation ». Shock and Vibration 2022 (18 mars 2022) : 1–12. http://dx.doi.org/10.1155/2022/3137447.
Texte intégralRésumé :
An inverse wave modeling-based method is proposed for globally reconstructing the sound field in room environments. The method builds the wave model of the sound field as prior knowledge to support the reconstruction under strong reverberation. In this method, the whole space is divided into a set of subdomains. Based on the theory of discretization-based numerical simulation, a wave model that can describe the transfer characteristic between any subdomain and the source is built. Supported by this model, the sound source is recovered based on spatial sound pressure sampling and the global sound field reconstruction can be further accomplished in the reverberant environment. In particular, the shape function with the property of sparsity is constructed in building the wave model. Then, the intensity on the point source is represented by a sparse vector over the subdomains, and then, the sparse method can be used to achieve the recovery of this vector, which reduces the sampling burden in the space. Numerical verifications are performed to evaluate the performances of the proposed method. It demonstrates that the proposed method is capable of obtaining accurate reconstructions in a strong reverberant environment. It also shows that the method is applicable to problems with complicated excitations in the low-frequency range.
16
Lee, Jyh-Fa, Ming-Shium Hsieh, Chih-Wei Kuo, Ming-Dar Tsai et Ming Ma. « REAL-TIME THREE-DIMENSIONAL RECONSTRUCTION FOR VOLUME-BASED SURGERY SIMULATIONS ». Biomedical Engineering : Applications, Basis and Communications 20, no 04 (août 2008) : 205–18. http://dx.doi.org/10.4015/s1016237208000799.
Texte intégralRésumé :
This paper describes a three-dimensional reconstruction method to provide real-time visual responses for volume (constituted by tomographic slices) based surgery simulations. The proposed system uses dynamical data structures to record tissue triangles obtained from 3D reconstruction computation. Each tissue triangle in the structures can be modified or every structure can be deleted or allocated independently. Moreover, triangle reconstruction is optimized by only deleting or adding vertices from manipulated voxels that are classified as erosion (in which the voxels are changed from tissue to null) or generation (the voxels are changed from null to tissue). Therefore, by manipulating these structures, 3D reconstruction can be locally implemented for only manipulated voxels to achieve the highest efficiency without reconstructing tissue surfaces in the whole volume as general methods do. Three surgery simulation examples demonstrate that the proposed method can provide time-critical visual responses even under other time-consuming computations such as volume manipulations and haptic interactions.
17
Zhao, Yong Xiang, Bing Yang et Wei Hua Zhang. « Statistical Reconstruction of the One-Dimensional Mechanical and Fatigue Strengths ». Key Engineering Materials 353-358 (septembre 2007) : 2493–96. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2493.
Texte intégralRésumé :
A Monte-Carlo simulation method for the reconstruction of one-dimensional probabilistic mechanical and fatigue strengths is developed to realize reliability analysis at arbitrary probability and confidence levels. This method is valid to the cases of the probabilistic parameters given at special probabilities (Ps) or probability-confidences (P-Cs). To overcome the shortage of common simulations with numerous samples which is out of true production practice, a simulation policy is newly suggested with 7 to 20 samples for material small specimens and, at most 10 for structural specimens and 5 percentages for the error of simulated parameters fitting the original ones. Details of the method in practice are studied for the six possible statistical distributions i.e. normal, lognormal, three-parameter Weibull, two-parameter Weibull, maximum value, and minimum value ones. The reconstructions of the fatigue limits of 10 Chinese engineering materials have indicated the availability and feasibility of the present method.
18
Hùng Anh, Lý, Nguyễn Phụ Thượng Lưu, Nguyễn Thiên Phú et Trần Đình Nhật. « Reconstruction finite element model of cars ». Science & ; Technology Development Journal - Engineering and Technology 4, no 1 (13 mars 2021) : first. http://dx.doi.org/10.32508/stdjet.v4i1.782.
Texte intégralRésumé :
The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.
19
Medeiros, Lia, Dimitrios Psaltis, Tod R. Lauer et Feryal Özel. « Principal-component Interferometric Modeling (PRIMO), an Algorithm for EHT Data. I. Reconstructing Images from Simulated EHT Observations ». Astrophysical Journal 943, no 2 (1 février 2023) : 144. http://dx.doi.org/10.3847/1538-4357/acaa9a.
Texte intégralRésumé :
Abstract The sparse interferometric coverage of the Event Horizon Telescope (EHT) poses a significant challenge for both reconstruction and model fitting of black hole images. PRIMO is a new principal components analysis-based algorithm for image reconstruction that uses the results of high-fidelity general relativistic, magnetohydrodynamic simulations of low-luminosity accretion flows as a training set. This allows the reconstruction of images that are consistent with the interferometric data and that live in the space of images that is spanned by the simulations. PRIMO follows Monte Carlo Markov Chains to fit a linear combination of principal components derived from an ensemble of simulated images to interferometric data. We show that PRIMO can efficiently and accurately reconstruct synthetic EHT data sets for several simulated images, even when the simulation parameters are significantly different from those of the image ensemble that was used to generate the principal components. The resulting reconstructions achieve resolution that is consistent with the performance of the array and do not introduce significant biases in image features such as the diameter of the ring of emission.
20
Cruz, Fernando, José P. Faria, Miguel Rocha, Isabel Rocha et Oscar Dias. « A review of methods for the reconstruction and analysis of integrated genome-scale models of metabolism and regulation ». Biochemical Society Transactions 48, no 5 (17 septembre 2020) : 1889–903. http://dx.doi.org/10.1042/bst20190840.
Texte intégralRésumé :
The current survey aims to describe the main methodologies for extending the reconstruction and analysis of genome-scale metabolic models and phenotype simulation with Flux Balance Analysis mathematical frameworks, via the integration of Transcriptional Regulatory Networks and/or gene expression data. Although the surveyed methods are aimed at improving phenotype simulations obtained from these models, the perspective of reconstructing integrated genome-scale models of metabolism and gene expression for diverse prokaryotes is still an open challenge.
21
Yuan, Zhen, et Huabei Jiang. « Quantitative photoacoustic tomography ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 367, no 1900 (13 août 2009) : 3043–54. http://dx.doi.org/10.1098/rsta.2009.0083.
Texte intégralRésumé :
In this paper, several algorithms that allow for quantitative photoacoustic reconstruction of tissue optical, acoustic and physiological properties are described in a finite-element method based framework. These quantitative reconstruction algorithms are compared, and the merits and limitations associated with these methods are discussed. In addition, a multispectral approach is presented for concurrent reconstructions of multiple parameters including deoxyhaemoglobin, oxyhaemoglobin and water concentrations as well as acoustic speed. Simulation and in vivo experiments are used to demonstrate the effectiveness of the reconstruction algorithms presented.
22
Deng, Yujuan. « Fluid Equation-Based and Data-Driven Simulation of Special Effects Animation ». Advances in Mathematical Physics 2021 (22 novembre 2021) : 1–11. http://dx.doi.org/10.1155/2021/7480422.
Texte intégralRésumé :
This paper analyzes the simulation of special effects animation through fluid equations and data-driven methods. This paper also considers the needs of computer fluid animation simulation in terms of computational accuracy and simulation efficiency, takes high real-time, high interactivity, and high physical accuracy of simulation algorithm as the research focus and target, and proposes a solution algorithm and acceleration scheme based on deep neural network framework for the key problems of simulation of natural phenomena including smoke and liquid. With the deep development of artificial intelligence technology, deep neural network models are widely used in research fields such as computer image classification, speech recognition, and fluid detail synthesis with their powerful data learning capability. Its stable and efficient computational model provides a new problem-solving approach for computerized fluid animation simulation. In terms of time series reconstruction, this paper adopts a tracking-based reconstruction method, including target tracking, 2D trajectory fitting and repair, and 3D trajectory reconstruction. For continuous image sequences, a linear dynamic model algorithm based on pyramidal optical flow is used to track the feature centers of the objects, and the spatial coordinates and motion parameters of the feature points are obtained by reconstructing the motion trajectories. The experimental results show that in terms of spatial reconstruction, the matching method proposed in this paper is more accurate compared with the traditional stereo matching algorithm; in terms of time series reconstruction, the error of target tracking reduced. Finally, the 3D motion trajectory of the point feature object and the motion pattern at a certain moment are shown, and the method in this paper obtains more ideal results, which proves the effectiveness of the method.
23
Sardari Nia, Peyman, Jules R. Olsthoorn, Samuel Heuts et Jos G. Maessen. « Interactive 3D Reconstruction of Pulmonary Anatomy for Preoperative Planning, Virtual Simulation, and Intraoperative Guiding in Video-Assisted Thoracoscopic Lung Surgery ». Innovations : Technology and Techniques in Cardiothoracic and Vascular Surgery 14, no 1 (février 2019) : 17–26. http://dx.doi.org/10.1177/1556984519826321.
Texte intégralRésumé :
Objectives Routine imaging modalities combined with state-of-the-art reconstruction software can substantially improve preoperative planning and simplify complex procedure by enhancing the surgeon’s knowledge of the patient’s specific anatomy. The aim of the current study was to demonstrate the feasibility of interactive three-dimensional (3D) computed tomography (CT) reconstructions for preoperative planning and intraoperative guiding in video-assisted thoracoscopic lung surgery (VATS) with 3D vision. Methods Twenty-five consecutive patients referred for an anatomic pulmonary resection by a single surgeon were included. Data were collected prospectively. All patients underwent a CT angiography in the diagnostic pathway prior to referral. 3D reconstruction of the pulmonary anatomy was obtained from CT scans with dedicated software. An interactive PDF file of the 3D reconstruction with virtual resection was created, in which all the pulmonary structures could be individually selected. Furthermore, the reconstructions were used for intraoperative guiding on double monitor during VATS with 3D vision. Results In total, 26 procedures were performed for 5 benign and 21 malignant conditions. Lobectomy and segmentectomy were performed in 20 (76.9 %) and 6 (23.1%) cases, respectively. In all patients, preoperative 3D reconstruction of pulmonary vessels corresponded with the intraoperative findings. Reconstructions revealed anatomic variations in 4 (15.4%) patients. No conversion to thoracotomy or in-hospital mortality occurred. Conclusions Preoperative planning with interactive 3D CT reconstruction is a useful method to enhance the surgeon’s knowledge of the patient’s specific anatomy and to reveal anatomic variations. Intraoperative 3D guiding in VATS with 3D vision is feasible and could contribute to the safety and accuracy of anatomic resection.
24
Szűcs, Herman. « Reconstruction of 3D Porous Geometry for Coupled FEM-CFD Simulation ». Periodica Polytechnica Mechanical Engineering 66, no 2 (22 mars 2022) : 129–36. http://dx.doi.org/10.3311/ppme.19438.
Texte intégralRésumé :
Porous materials can be found in numerous areas of life (e. g., applied science, material science), however, the simulation of the fluid flow and transport phenomena through porous media is a significant challenge nowadays. Numerical simulations can help to analyze and understand physical processes and different phenomena in the porous structure, as well as to determine certain parameters that are difficult or impossible to measure directly or can only be determined by expensive and time-consuming experiments. The basic condition for the numerical simulations is the 3D geometric model of the porous material sample, which is the input parameter of the simulation. For this reason, geometry reconstruction is highly critical for pore-scale analysis. This paper introduces a complex process for the preparation of the microstructure's geometry in connection with a coupled FEM-CFD two-way fluid-structure interaction simulation. Micro-CT has been successfully applied to reconstruct both the fluid and solid phases of the used porous material.
25
Huang, W. P., C. Y. Ku, L. K. Chien et C. J. Ye. « Hydraulic Simulation of Waterbird Habitat Reconstruction ». E3S Web of Conferences 101 (2019) : 04001. http://dx.doi.org/10.1051/e3sconf/201910104001.
Texte intégralRésumé :
Cigu wetland consists of industrial salt ponds and lagoon is situated at the coast in the southwestern of Taiwan which is demarcated as Coastal Nature Reserve. The salt ponds experienced declines in bird species diversity and population compared with those within the lagoon area due to the deeper water depths. Different kinds of measures to alter water depths of salt ponds by filling soil are proposed. The hydrodynamic simulations were conducted for studying the hydrodynamic response to proposed reconstruction alternatives. The potential waterbird abundance was then estimated for the alternative recommendation. The methodology proposed in this study can reduce the risk of unexpected results by implementing the reconstruction project directly.
26
Sousa, Luisa Costa, Catarina F. Castro, Carlos Conceição António et Rui Chaves. « Blood flow simulation and vascular reconstruction ». Journal of Biomechanics 45, no 15 (octobre 2012) : 2549–55. http://dx.doi.org/10.1016/j.jbiomech.2012.07.033.
Texte intégral
27
Dale, P. A. D. M. A., et D. W. Bullett. « Simulation of Adsorbate-Induced Surface Reconstruction ». Molecular Simulation 4, no 1-3 (octobre 1989) : 187–92. http://dx.doi.org/10.1080/08927028908021974.
Texte intégral
28
Markram, Henry, Eilif Muller, Srikanth Ramaswamy, Michael W. Reimann, Marwan Abdellah, Carlos Aguado Sanchez, Anastasia Ailamaki et al. « Reconstruction and Simulation of Neocortical Microcircuitry ». Cell 163, no 2 (octobre 2015) : 456–92. http://dx.doi.org/10.1016/j.cell.2015.09.029.
Texte intégral
29
Rodrigo, F. S., J. J. Gómez-Navarro et J. P. Montávez Gómez. « Climate variability in Andalusia (southern Spain) during the period 1701–1850 AD from documentary sources : evaluation and comparison with climate model simulations ». Climate of the Past Discussions 7, no 4 (7 juillet 2011) : 2297–339. http://dx.doi.org/10.5194/cpd-7-2297-2011.
Texte intégralRésumé :
Abstract. In this work, a reconstruction of climatic conditions in Andalusia (southern Iberia Peninsula) during the period 1701–1850, as well as an evaluation of its associated uncertainties, is presented. This period is interesting because it is characterized by a minimum in the solar irradiance (Dalton Minimum, around 1800), as well as intense volcanic activity (for instance, the eruption of the Tambora in 1815), when the increasing atmospheric CO2 concentrations were of minor importance. The reconstruction is based on the analysis of a wide variety of documentary data. The reconstruction methodology is based on accounting the number of extreme events in past, and inferring mean value and standard deviation using the assumption of normal distribution for the seasonal means of climate variables. This reconstruction methodology is tested within the pseudoreality of a high-resolution paleoclimate simulation performed with the regional climate model MM5 coupled to the global model ECHO-G. Results show that the reconstructions are influenced by the reference period chosen and the threshold values used to define extreme values. This creates uncertainties which are assesed within the context of the climate simulation. An ensemble of reconstructions was obtained using two different reference periods and two pairs of percentiles as threshold values. Results correspond to winter temperature, and winter, spring, and autumn rainfall, and they are compared with simulations of the climate model for the considered period. The comparison of the distribution functions corresponding to 1790–1820 and 1960–1990 periods indicates that during the Dalton Minimum the frequency of dry and warm (wet and cold) winters was lesser (higher) than during the reference period. In spring and autumn it was detected an increase (decrease) in the frequency of wet (dry) seasons. Future research challenges are outlined.
30
Wang, Wu, Artur Svidrytski, Di Wang, Alberto Villa, Horst Hahn, Ulrich Tallarek et Christian Kübel. « Quantifying Morphology and Diffusion Properties of Mesoporous Carbon From High-Fidelity 3D Reconstructions ». Microscopy and Microanalysis 25, no 4 (21 juin 2019) : 891–902. http://dx.doi.org/10.1017/s1431927619014600.
Texte intégralRésumé :
AbstractA reliable quantitative analysis in electron tomography, which depends on the segmentation of the three-dimensional reconstruction, is challenging because of constraints during tilt-series acquisition (missing wedge) and reconstruction artifacts introduced by reconstruction algorithms such as the Simultaneous Iterative Reconstruction Technique (SIRT) and Discrete Algebraic Reconstruction Technique (DART). We have carefully evaluated the fidelity of segmented reconstructions analyzing a disordered mesoporous carbon used as support in catalysis. Using experimental scanning transmission electron microscopy (STEM) tomography data as well as realistic phantoms, we have quantitatively analyzed the effect on the morphological description as well as on diffusion properties (based on a random-walk particle-tracking simulation) to understand the role of porosity in catalysis. The morphological description of the pore structure can be obtained reliably both using SIRT and DART reconstructions even in the presence of a limited missing wedge. However, the measured pore volume is sensitive to the threshold settings, which are difficult to define globally for SIRT reconstructions. This leads to noticeable variations of the diffusion coefficients in the case of SIRT reconstructions, whereas DART reconstructions resulted in more reliable data. In addition, the anisotropy of the determined diffusion properties was evaluated, which was significant in the presence of a limited missing wedge for SIRT and strongly reduced for DART.
31
Aziz, Ahmed, Karan Singh, Ahmed Elsawy, Walid Osamy et Ahmed M. Khedr. « GWRA : grey wolf based reconstruction algorithm for compressive sensing signals ». PeerJ Computer Science 5 (2 septembre 2019) : e217. http://dx.doi.org/10.7717/peerj-cs.217.
Texte intégralRésumé :
The recent advances in compressive sensing (CS) based solutions make it a promising technique for signal acquisition, image processing and other types of data compression needs. In CS, the most challenging problem is to design an accurate and efficient algorithm for reconstructing the original data. Greedy-based reconstruction algorithms proved themselves as a good solution to this problem because of their fast implementation and low complex computations. In this paper, we propose a new optimization algorithm called grey wolf reconstruction algorithm (GWRA). GWRA is inspired from the benefits of integrating both the reversible greedy algorithm and the grey wolf optimizer algorithm. The effectiveness of GWRA technique is demonstrated and validated through rigorous simulations. The simulation results show that GWRA significantly exceeds the greedy-based reconstruction algorithms such as sum product, orthogonal matching pursuit, compressive sampling matching pursuit and filtered back projection and swarm based techniques such as BA and PSO in terms of reducing the reconstruction error, the mean absolute percentage error and the average normalized mean squared error.
32
Phillpot, S. R. « Reconstruction of grain boundaries in copper and gold by simulation ». Journal of Materials Research 9, no 3 (mars 1994) : 582–91. http://dx.doi.org/10.1557/jmr.1994.0582.
Texte intégralRésumé :
The reconstructions of high-angle twist grain boundaries on the four densest atomic planes in fcc copper, as described by a Lennard-Jones potential, and gold, as described by an embedded-atom-method potential, are investigated using the recently developed method of grand-canonical simulated quenching. It is found that the grain boundaries on the widely spaced (111) and (100) planes do not reconstruct, while those on the less widely spaced (110) and (113) planes do reconstruct. The effect that reconstruction can have on the physical properties of an interfacial system is illustrated by comparing the elastic properties and ideal cleavage energies of reconstructed grain boundaries with those of corresponding unreconstructed grain boundaries.
33
Jiang, Hong Hua, Yu Jiang Wang et Yu Xiang. « The Simulation and Accuracy Analysis of Sound Filed Reconstruction Based on Fourier Transform-Source Simulation Technique ». Advanced Materials Research 1061-1062 (décembre 2014) : 780–87. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.780.
Texte intégralRésumé :
Acoustic transform algorithm plays an important role in sound pressure reconstruction. According to a new sound pressure reconstruction of near-field acoustic holography based on Fourier transform-source simulation technique, this article through a simulation experiment with the models of Simply Supported Plate Sound Source, verify the feasibility of the method. Furthermore, in order to verify the effectiveness of this method, this paper analyzes the impact factors that affect the accuracy of the Reconstruction. And it does simulation analysis mainly from the parameters of the Virtual Source Plane, the Distance of the Holographic Measurement and the parameters of the Holographic plane. Therefore this study provided referencing basis for later study on complex field of sound pressure reconstruction based on this technology.
34
XIE, X. P., M. H. LIANG, Z. M. CHOO et S. LI. « A COMPARATIVE SIMULATION STUDY OF SILICON (001) SURFACE RECONSTRUCTION USING DIFFERENT INTERATOMIC POTENTIALS ». Surface Review and Letters 08, no 05 (octobre 2001) : 471–75. http://dx.doi.org/10.1142/s0218625x01001397.
Texte intégralRésumé :
We have performed a comparative study of Si (001) surface reconstruction employing molecular dynamics simulation using the interatomic potentials of Stillinger–Weber, Tersoff and Bazant–Kaxiras. Simulations were carried out for temperatures at 300 K and 1000 K using each of these three potentials. At 300 K, the three potentials were found to generate surface features comprising mainly the simple (2 × 1) reconstruction. At 1000 K, more complex reconstruction similar to the p (2 × 2) and c (2 × 2) patterns was observed on the surfaces of Stillinger–Weber and Tersoff crystals while the surface generated on Bazant–Kaxiras crystal is characterized by disorderliness with no identifiable pattern of reconstruction.
35
Peter, Jörg. « Musiré : multimodal simulation and reconstruction framework for the radiological imaging sciences ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 379, no 2204 (5 juillet 2021) : 20200190. http://dx.doi.org/10.1098/rsta.2020.0190.
Texte intégralRésumé :
A software-based workflow is proposed for managing the execution of simulation and image reconstruction for SPECT, PET, CBCT, MRI, BLI and FMI packages in single and multimodal biomedical imaging applications. The workflow is composed of a Bash script, the purpose of which is to provide an interface to the user, and to organize data flow between dedicated programs for simulation and reconstruction. The currently incorporated simulation programs comprise GATE for Monte Carlo simulation of SPECT, PET and CBCT, SpinScenario for simulating MRI, and Lipros for Monte Carlo simulation of BLI and FMI. Currently incorporated image reconstruction programs include CASToR for SPECT and PET as well as RTK for CBCT. MetaImage (mhd) standard is used for voxelized phantom and image data format. Meshlab project (mlp) containers incorporating polygon meshes and point clouds defined by the Stanford triangle format (ply) are employed to represent anatomical structures for optical simulation, and to represent tumour cell inserts. A number of auxiliary programs have been developed for data transformation and adaptive parameter assignment. The software workflow uses fully automatic distribution to, and consolidation from, any number of Linux workstations and CPU cores. Example data are presented for clinical SPECT, PET and MRI systems using the Mida head phantom and for preclinical X-ray, PET and BLI systems employing the Digimouse phantom. The presented method unifies and simplifies multimodal simulation setup and image reconstruction management and might be of value for synergistic image research. This article is part of the theme issue ‘Synergistic tomographic image reconstruction: part 2’.
36
Wang, Xiao Hui. « Virtual Simulation of Aerobics Movement Based on Vision ». Advanced Materials Research 989-994 (juillet 2014) : 1997–2000. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.1997.
Texte intégralRésumé :
In aerobics, the motion state randomness of key feature points is great, so it is difficult to establish an accurate dynamic model for sports' shape base. Traditional 3D reconstruction algorithms use fixes shape base which hardly expresses the change parameters of complex movement and motion law of large-scale dynamic features, thereby leading to non-realistic reconstruction results. The paper proposes a new reconstruction algorithm for aerobics 3D motion images that corrects the neighborhood system of feature points by motion parameters until the parameter is stable to ensure accuracy and the stability of correction. The simulation results show that, the proposed algorithm avoids drawbacks of sports reconstruction results caused by the great randomness of aerobics' motion state, thereby complete 3D reconstruction for aerobics' motion images.
37
Dissard, Delphine, Gert Jan Reichart, Christophe Menkes, Morgan Mangeas, Stephan Frickenhaus et Jelle Bijma. « Mg∕Ca, Sr∕Ca and stable isotopes from the planktonic foraminifera <i>T. sacculifer</i> ; : testing a multi-proxy approach for inferring paleotemperature and paleosalinity ». Biogeosciences 18, no 2 (19 janvier 2021) : 423–39. http://dx.doi.org/10.5194/bg-18-423-2021.
Texte intégralRésumé :
Abstract. Over the last decades, sea surface temperature (SST) reconstructions based on the Mg∕Ca of foraminiferal calcite have frequently been used in combination with the δ18O signal from the same material to provide estimates of the δ18O of water (δ18Ow), a proxy for global ice volume and sea surface salinity (SSS). However, because of error propagation from one step to the next, better calibrations are required to increase the accuracy and robustness of existing isotope and element to temperature proxy relationships. Towards that goal, we determined Mg∕Ca, Sr∕Ca and the oxygen isotopic composition of Trilobatus sacculifer (previously referenced as Globigerinoides sacculifer) collected from surface waters (0–10 m) along a north–south transect in the eastern basin of the tropical and subtropical Atlantic Ocean. We established a new paleotemperature calibration based on Mg∕Ca and on the combination of Mg∕Ca and Sr∕Ca. Subsequently, a sensitivity analysis was performed in which one, two or three different equations were considered. Results indicate that foraminiferal Mg∕Ca allows for an accurate reconstruction of surface water temperature. Combining equations, δ18Ow can be reconstructed with a precision of about ± 0.5 ‰. However, the best possible salinity reconstruction based on locally calibrated equations only allowed for a reconstruction with an uncertainty of ± 2.49. This was confirmed by a Monte Carlo simulation, applied to test successive reconstructions in an “ideal case” in which explanatory variables are known. This simulation shows that from a purely statistical point of view, successive reconstructions involving Mg∕Ca and δ18Oc preclude salinity reconstructions with a precision better than ± 1.69 and hardly better than ± 2.65 due to error propagation. Nevertheless, a direct linear fit to reconstruct salinity based on the same measured variables (Mg∕Ca and δ18Oc) was established. This direct reconstruction of salinity led to a much better estimation of salinity (± 0.26) than the successive reconstructions.
38
Wang, J., J. Emile-Geay, D. Guillot, J. E. Smerdon et B. Rajaratnam. « Evaluating climate field reconstruction techniques using improved emulations of real-world conditions ». Climate of the Past 10, no 1 (6 janvier 2014) : 1–19. http://dx.doi.org/10.5194/cp-10-1-2014.
Texte intégralRésumé :
Abstract. Pseudoproxy experiments (PPEs) have become an important framework for evaluating paleoclimate reconstruction methods. Most existing PPE studies assume constant proxy availability through time and uniform proxy quality across the pseudoproxy network. Real multiproxy networks are, however, marked by pronounced disparities in proxy quality, and a steep decline in proxy availability back in time, either of which may have large effects on reconstruction skill. A suite of PPEs constructed from a millennium-length general circulation model (GCM) simulation is thus designed to mimic these various real-world characteristics. The new pseudoproxy network is used to evaluate four climate field reconstruction (CFR) techniques: truncated total least squares embedded within the regularized EM (expectation-maximization) algorithm (RegEM-TTLS), the Mann et al. (2009) implementation of RegEM-TTLS (M09), canonical correlation analysis (CCA), and Gaussian graphical models embedded within RegEM (GraphEM). Each method's risk properties are also assessed via a 100-member noise ensemble. Contrary to expectation, it is found that reconstruction skill does not vary monotonically with proxy availability, but also is a function of the type and amplitude of climate variability (forced events vs. internal variability). The use of realistic spatiotemporal pseudoproxy characteristics also exposes large inter-method differences. Despite the comparable fidelity in reconstructing the global mean temperature, spatial skill varies considerably between CFR techniques. Both GraphEM and CCA efficiently exploit teleconnections, and produce consistent reconstructions across the ensemble. RegEM-TTLS and M09 appear advantageous for reconstructions on highly noisy data, but are subject to larger stochastic variations across different realizations of pseudoproxy noise. Results collectively highlight the importance of designing realistic pseudoproxy networks and implementing multiple noise realizations of PPEs. The results also underscore the difficulty in finding the proper bias-variance tradeoff for jointly optimizing the spatial skill of CFRs and the fidelity of the global mean reconstructions.
39
GRAF, NORMAN A. « LINEAR COLLIDER DETECTOR SIMULATION OVERVIEW ». International Journal of Modern Physics A 20, no 15 (20 juin 2005) : 3385–88. http://dx.doi.org/10.1142/s0217751x05026601.
Texte intégralRésumé :
We describe the ILC detector simulation environment, which features a flexible GEANT4-based detector response program and a Java toolkit for full event reconstruction and analysis. The toolkit is currently being used for detector design and physics analysis for a future e+e- linear collider. The reconstruction components are fully modular and are available for tasks from digitization of tracking detector signals through to cluster finding, pattern recognition, fitting, jetfinding, and analysis.
40
Hua, Jing, Hua Zhang, Jizhong Liu et Junlong Zhou. « Compressive Sensing of Multichannel Electrocardiogram Signals in Wireless Telehealth System ». Journal of Circuits, Systems and Computers 25, no 09 (21 juin 2016) : 1650103. http://dx.doi.org/10.1142/s0218126616501036.
Texte intégralRésumé :
Due to the capacity of compressing and recovering signal with low energy consumption, compressive sensing (CS) has drawn considerable attention in wireless telemonitoring of electrocardiogram (ECG) signals. However, most existing CS methods are designed for reconstructing single channel signal, and hence difficult to reconstruct multichannel ECG signals. In this paper, a spatio-temporal sparse model-based algorithm is proposed for the reconstruction of multichannel ECG signals by not only exploiting the temporal correlation in each individual channel signal, but also the spatial correlation among signals from different channels. In addition, a dictionary learning (DL) approach is developed to enhance the performance of the proposed reconstruction algorithm by using the sparsity of ECG signals in some transformed domain. The approach determines a dictionary by learning local dictionaries for each channel and merging them to form a global dictionary. Extensive simulations were performed to validate the proposed algorithms. Simulation results show that the proposed reconstruction algorithm has a better performance in recovering multichannel ECG signals as compared to the benchmarking methods. Moreover, the reconstruction performance of the algorithm can be further improved by using a dictionary matrix, which is obtained from the proposed DL algorithm.
41
Al Hosani, E., et M. Soleimani. « Multiphase permittivity imaging using absolute value electrical capacitance tomography data and a level set algorithm ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 374, no 2070 (28 juin 2016) : 20150332. http://dx.doi.org/10.1098/rsta.2015.0332.
Texte intégralRésumé :
Multiphase flow imaging is a very challenging and critical topic in industrial process tomography. In this article, simulation and experimental results of reconstructing the permittivity profile of multiphase material from data collected in electrical capacitance tomography (ECT) are presented. A multiphase narrowband level set algorithm is developed to reconstruct the interfaces between three- or four-phase permittivity values. The level set algorithm is capable of imaging multiphase permittivity by using one set of ECT measurement data, so-called absolute value ECT reconstruction, and this is tested with high-contrast and low-contrast multiphase data. Simulation and experimental results showed the superiority of this algorithm over classical pixel-based image reconstruction methods. The multiphase level set algorithm and absolute ECT reconstruction are presented for the first time, to the best of our knowledge, in this paper and critically evaluated. This article is part of the themed issue ‘Supersensing through industrial process tomography’.
42
Zanchettin, D., O. Bothe, F. Lehner, P. Ortega, C. C. Raible et D. Swingedouw. « Reconciling reconstructed and simulated features of the winter Pacific–North-American pattern in the early 19th century ». Climate of the Past Discussions 10, no 6 (26 novembre 2014) : 4425–68. http://dx.doi.org/10.5194/cpd-10-4425-2014.
Texte intégralRésumé :
Abstract. Reconstructions of past climate behavior often describe prominent anomalous periods that are not necessarily captured in climate simulations. Here, we illustrate the contrast between an interdecadal strong positive phase of the winter Pacific/North American pattern (PNA) in the early 19th century that is described by a PNA reconstruction based on tree-rings from northwestern North America, and a slight tendency towards negative winter PNA anomalies during the same period in an ensemble of state-of-the-art coupled climate simulations. Additionally, a pseudo-proxy investigation with the same simulation ensemble allows assessing the robustness of PNA reconstructions using solely geophysical predictors from northwestern North America for the last millennium. The reconstructed early-19th-century positive PNA anomaly emerges as a potentially reliable feature, although it is subject to a number of sources of uncertainty and potential deficiencies. The pseudo-reconstructions demonstrate that the early-19th-century discrepancy between reconstructed and simulated PNA does not stem from the reconstruction process. Instead, reconstructed and simulated features of the early-19th-century PNA can be reconciled by interpreting the reconstructed evolution during this time as an expression of internal climate variability, hence unlikely to be reproduced in its exact temporal occurrence by a small ensemble of climate simulations. However, firm attribution of the reconstructed PNA anomaly is hampered by known limitations and deficiencies of coupled climate models and uncertainties in the early-19th-century external forcing and background climate conditions.
43
Kolla, Eduard, Ján Ondruš et Peter Vertaľ. « Reconstruction of traffic situations from digital video-recording using method of volumetric kinetic mapping ». Archives of Automotive Engineering – Archiwum Motoryzacji 84, no 2 (28 juin 2019) : 147–70. http://dx.doi.org/10.14669/am.vol84.art11.
Texte intégralRésumé :
In the past the traffic accident reconstruction was based in principle only on indirect methods that use accident marks and witness reports. These data were then used within backward reconstruction of event for determination of motion status of accident participants and expression of desirable quantities as are initial velocities, impact velocities, distances travelled or temporal conditions. These methods and their accuracy are dependent on the width of intervals of input quantities or on limited possibilities for motion synchronization between numerable participants of road traffic accidents. Existence of footage from CCTV cameras that captures traffic situations presents very valuable source of information about these accidents. The goal of the article is proposal of a volumetric kinetic mapping (VKM) method of accident reconstruction from CCTV footage. The method is based on synthesis of videoediting, videoanalysis and kinetic simulation using dedicated software for accident reconstruction. The method was furthermore validated for speed-time and distance-time variables by means of experimental test runs and by subsequent application of the method in the reconstruction of these tests using PC-Crash simulation software and two videoediting software packages. Results of the reconstructions of validation runs using VKM method were then verified by comparing them to the measured data from Corrsys Datron Microstar measuring system.
44
Zanchettin, D., O. Bothe, F. Lehner, P. Ortega, C. C. Raible et D. Swingedouw. « Reconciling reconstructed and simulated features of the winter Pacific/North American pattern in the early 19th century ». Climate of the Past 11, no 6 (24 juin 2015) : 939–58. http://dx.doi.org/10.5194/cp-11-939-2015.
Texte intégralRésumé :
Abstract. Reconstructions of past climate behavior often describe prominent anomalous periods that are not necessarily captured in climate simulations. Here, we illustrate the contrast between an interdecadal strong positive phase of the winter Pacific/North American pattern (PNA) in the early 19th century that is described by a PNA reconstruction based on tree rings from northwestern North America, and a slight tendency towards negative winter PNA anomalies during the same period in an ensemble of state-of-the-art coupled climate simulations. Additionally, a pseudo-proxy investigation with the same simulation ensemble allows for assessing the robustness of PNA reconstructions using solely geophysical predictors from northwestern North America for the last millennium. The reconstructed early 19th-century positive PNA anomaly emerges as a potentially reliable feature, although the pseudo-reconstructions are subject to a number of sources of uncertainty and deficiencies highlighted especially at multidecadal and centennial timescales. The pseudo-reconstructions demonstrate that the early 19th-century discrepancy between reconstructed and simulated PNA does not stem from the reconstruction process. Instead, reconstructed and simulated features of the early 19th-century PNA can be reconciled by interpreting the reconstructed evolution during this time as an expression of internal climate variability, which is unlikely to be reproduced in its exact temporal occurrence by a small ensemble of climate simulations. However, firm attribution of the reconstructed PNA anomaly is hampered by known limitations and deficiencies of coupled climate models and uncertainties in the early 19th-century external forcing and background climate state.
45
Chen, Huihong, et Shiming Li. « Simulation of 3D Image Reconstruction in Rigid body Motion ». MATEC Web of Conferences 232 (2018) : 02002. http://dx.doi.org/10.1051/matecconf/201823202002.
Texte intégralRésumé :
3D image reconstruction under rigid body motion is affected by rigid body motion and visual displacement factors, which leads to low quality of 3D image reconstruction and more noise, in order to improve the quality of 3D image reconstruction of rigid body motion. A 3D image reconstruction technique is proposed based on corner detection and edge contour feature extraction in this paper. Region scanning and point scanning are combined to scan rigid body moving object image. The wavelet denoising method is used to reduce the noise of the 3D image. The edge contour feature of the image is extracted. The sparse edge pixel fusion method is used to decompose the feature of the 3D image under the rigid body motion. The irregular triangulation method is used to extract and reconstruct the information features of the rigid body 3D images. The reconstructed feature points are accurately calibrated with the corner detection method to realize the effective reconstruction of the 3D images. The simulation results show that the method has good quality, high SNR of output image and high registration rate of feature points of image reconstruction, and proposed method has good performance of 3D image reconstruction.
46
Zhang, Wenchao, Bo Zhang, Fei Xu et Mohammad Asif. « Research on Numerical Simulation Method of Nonstationary Random Vibration Signal Sensor in Railway Transportation ». Journal of Sensors 2022 (15 avril 2022) : 1–7. http://dx.doi.org/10.1155/2022/7149477.
Texte intégralRésumé :
During railway transportation, due to various factors such as road conditions and operating conditions and produced vibrations and shocks, this kind of vibration environment may cause fatigue damage to on-board equipment and transported goods. The authors propose a research on the numerical simulation method of the nonstationary random vibration signal sensor of railway transportation; first, they establish the mathematical model of the railway nonstationary random vibration signal sensor and then introduce the method of reconstructing the railway nonstationary random vibration signal sensor. For railway nonstationary non-Gaussian random vibration reconstruction signal, compare the time-domain characteristics of the sampled signal, and for railway nonstationary non-Gaussian random vibration reconstruction signal, compare the frequency domain characteristics of the sampled signal. The results show that the relative error of the RMSM function is within 6%, the relative error of the sliding bias function is within 10%, and the relative error of the sliding kurtosis function is within 8%. The energy distribution of the edge Hilbert amplitude spectrum is very similar, with absolute error less than 6%. The energy fluctuations are similar in each band, with absolute error rates less than 4% in most bands. The method proposed in this article, suitable for reconstruction of railway nonstationary Gaussian random vibration and nonstationary non-Gaussian vibration signal sensor, verifies the effectiveness and feasibility of the signal reconstruction method. The model and signal reconstruction method proposed in this paper are applied to the railway nonstationary Gaussian and nonstationary non-Gaussian random vibration sampling signals.
47
Gómez-Navarro, J. J., O. Bothe, S. Wagner, E. Zorita, J. P. Werner, J. Luterbacher, C. C. Raible et J. P. Montávez. « A~regional climate palaeosimulation for Europe in the period 1501–1990 – Part II : Comparison with gridded reconstructions ». Climate of the Past Discussions 11, no 1 (13 février 2015) : 307–43. http://dx.doi.org/10.5194/cpd-11-307-2015.
Texte intégralRésumé :
Abstract. This study jointly analyses gridded European winter and summer surface air temperature (SAT) and precipitation reconstructions and a regional climate simulation over the period 1501–1990. The European area is analysed separately for nine sub-areas. In their spatial structure, an overall good agreement is found between the reconstructed and simulated climate variability across different areas of Europe, supporting a consistency of both products and the proper calibration of the reconstructions. Still, systematic biases appear between both datasets that can be explained by a priori known deficiencies in the simulation. However, simulations and reconstructions largely differ in their estimates of the temporal evolution of past climate for European sub-regions. In particular, the simulated anomalies during the Maunder and Dalton minima show stronger response to changes in the external forcings than recorded in the reconstructions. This disagreement is to some extent expected given the prominent role of internal variability in the evolution of regional temperature and precipitation. However, the inability of the model to reproduce a warm period similar to that recorded around 1740 in winter reconstructions is indicative of fundamental limitations in the simulation that preclude reproducing exceptionally anomalous conditions. Despite these limitations, the simulated climate is a physically consistent dataset, which can be used as a benchmark to analyse the consistency and limitations of gridded reconstructions of different variables. Comparison of the main variability modes of SAT and precipitation indicates that reconstructions present too simplistic character of (natural) variability modes, especially for precipitation. This can be explained through the linear statistical techniques used for reconstruction. The analysis of the co-variability among variables shows that the simulation captures reasonable well the canonical co-variability, whereas independent reconstructions show unrealistically low correlations. Thus, the analysis points to a lack of dynamic consistency that reduces the confidence for subcontinental European reconstructions.
48
Shi, Guang, Leijue Zheng, Wen Wang et Keqing Lu. « Non-Scanning Three-Dimensional Imaging System with a Single-Pixel Detector : Simulation and Experimental Study ». Applied Sciences 10, no 9 (29 avril 2020) : 3100. http://dx.doi.org/10.3390/app10093100.
Texte intégralRésumé :
Existing scanning laser three-dimensional (3D) imaging technology has slow measurement speed. In addition, the measurement accuracy of non-scanning laser 3D imaging technology based on area array detectors is limited by the resolution and response frequency of area array detectors. As a result, applications of laser 3D imaging technology are limited. This paper completed simulations and experiments of a non-scanning 3D imaging system with a single-pixel detector. The single-pixel detector can be used to achieve 3D imaging of a target by compressed sensing to overcome the shortcomings of the existing laser 3D imaging technology. First, the effects of different sampling rates, sparse transform bases, measurement matrices, and reconstruction algorithms on the measurement results were compared through simulation experiments. Second, a non-scanning 3D imaging experimental platform was designed and constructed. Finally, an experiment was performed to compare the effects of different sampling rates and reconstruction algorithms on the reconstruction effect of 3D imaging to obtain a 3D image with a resolution of 8 × 8. The simulation results show that the reconstruction effect of the Hadamard measurement matrix and the minimum total variation reconstruction algorithm performed well.
49
Maltseva, Olha. « Simulation of laughter : the experience of reconstruction ». Skhid, no 3(155) (29 juillet 2018) : 32–38. http://dx.doi.org/10.21847/1728-9343.2018.3(155).139403.
Texte intégral
50
Guan, Huaiqun, Fang-Fang Yin, Yunping Zhu et Jae Ho Kim. « Adaptive portal CT reconstruction : A simulation study ». Medical Physics 27, no 10 (octobre 2000) : 2209–14. http://dx.doi.org/10.1118/1.1312193.
Texte intégral