scholarly journals Comparative analysis of the error of the single scattering approximation when solving one inverse problem in two-dimensional and three- dimensional cases

2021 ◽  
Vol 21 (2) ◽  
pp. 151-165
Author(s):  
P.A. Vornovskikh ◽  
◽  
I.V. Prokhorov ◽  
Keyword(s):  
Inverse Problem ◽  
Comparative Analysis ◽  
Three Dimensional ◽  
Single Scattering ◽  
Two Dimensional ◽  
Three Dimensional Model ◽  
Acoustic Sounding ◽  
Scattering Approximation ◽  
Three Dimensional Models ◽  
Single Scattering Approximation

The inverse problem for the nonstationary radiative transfer equation is considered, which consists in finding the scattering coefficient for a given time-angular distribution of the solution to the equation at a certain point. To solve this problem, the single scattering approximation in the pulsed sounding mode is used. A comparative analysis of the error in solving the inverse problem in the single scattering approximation for two-dimensional and three-dimensional models describing the process of high-frequency acoustic sounding in a fluctuating ocean is carried out. It is shown that in the two-dimensional case the error of the approximate solution significantly exceeds the error in the three-dimensional model.

A New 3DGIS Development Technology Research Based on the Sketchup and SuperMap Platform

2013 ◽  
Vol 433-435 ◽  
pp. 1379-1382
Author(s):  
Bin Wu ◽  
Shi Kai Duan ◽  
Ling Liu
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Google Earth ◽  
Two Dimensional ◽  
Three Dimensional Model ◽  
Property Data ◽  
Development Technology ◽  
Pros And Cons ◽  
Three Dimensional Models ◽  
Google Sketchup

Analysis the pros and cons with the current three-dimensional GIS development techniques, we proposed a new three-dimensional GIS development technology based on Google Earth, Sketchup and SuperMap software, to better achieve the virtual digital of the three-dimensional model. The Google Earth software gets the two-dimensional area to be modeling image which imports into Google Sketchup software, establishment of two-dimensional vector graphics, and then build roads and construction of three-dimensional models. Then, SuperMap component realizes the integration of spatial data and attribute data integration management, the realization of digital based on data collection, classification, storage of property data and management. Based on this, we applied the development technology to the virtual campus three-dimensional navigation system. In this, some technology flow charts are given. Finally, compared with some other three-dimensional GIS development technologies, a discussion and conclusion presented. We call to apply three-dimensional GIS navigation.

Three-Dimensional Model for Manufacturing and Inspection

2013 ◽  
Author(s):  
Brian S. Pippenger
Keyword(s):  
Three Dimensional ◽  
Quality Measurement ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Dimensional Metrology ◽  
Three Dimensional Model ◽  
Model Based ◽  
Visual Aid ◽  
Inspection Systems ◽  
Three Dimensional Models

Three-dimensional Model-Based Engineering (MBE) along with Quality Information Framework (QIF) is an approach to product design, manufacturing, and support where a digital three-dimensional representation of the product serves as the normative source for information communicated throughout the product’s lifecycle and supply chain. MBE simplifies data management and provides a more powerful communication medium than 2D-based environments. This is not just using a model for reference or a visual aid. The model will be the definition for the parts being manufactured, inspected, and built into full engines. The use of two-dimensional prints will be outdated and a culture change will be needed to embrace this change. Many organizations are implementing MBE and are using this technology to produce aerospace products. Manufacturing and inspection functions are dependent on the models from cradle to grave of the product lifecycle. These smart models will have all of the necessary dimensional metrology interoperability, GD&T encoded and product manufacturing information (PMI) data all in a standardized format associated within the model. This will allow for a model that has less errors, more functionality with manufacturing and inspection systems. The information included in the Model Based Definition (MBD) will be part of the QIF. The QIF fully defines quality measurement plans, measurement results, measurement rules, measurement resources, and results analysis. This combined with the PMI for manufacturing will provide a comprehensive MBD that can be used for all of the manufacturing process in the lifecycle of the product. The culture will need to progress from two-dimensional paper prints to smart three-dimensional models that are rich with data. These models will drive the process and be the final word for part acceptance; paper prints will not be needed or produced. These types of models will drive almost all of the military’s new designs and if the organization is not prepared for this change, it will lose many opportunities to be competitive.

TERRAIN DECOMPOSITION AND LAYERED MANUFACTURING

2001 ◽  
Vol 11 (06) ◽  
pp. 647-668 ◽  
Author(s):  
SÁNDOR P. FEKETE ◽  
JOSEPH S. B. MITCHELL
Keyword(s):  
Three Dimensional ◽  
Layered Manufacturing ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Polygonal Region ◽  
Axis Parallel ◽  
Dimensional Version ◽  
Three Dimensional Models ◽  
Base Facet

We consider a problem that arises in generating three-dimensional models by methods of layered manufacturing: How does one decompose a given model P into a small number of sub-models each of which is a terrain polyhedron? Terrain polyhedra have a base facet such that, for each point of the polyhedron, the line segment joining the point to its orthogonal projection on the base facet lies within the polyhedron. Terrain polyhedra are exactly the class of polyhedral models for which it is possible to construct the model using layered manufacturing (with layers parallel to the base facet), without the need for constructing "supports" (which must later be removed). In order to maximize the integrity of a prototype, one wants to minimize the number of individual sub-models that are manufactured and then glued together. We show that it is NP-hard to decide if a three-dimensional model P of genus 0 can be decomposed into k terrain polyhedra. We also prove a two-dimensional version of this theorem, for the case in which P is a polygonal region with holes. Both results still hold if we are restricted to isothetic objects and/or axis-parallel layering directions.

scholarly journals Fast Hyper-Spectral Radiative Transfer Model Based on the Double Cluster Low-Streams Regression Method

2021 ◽  
Vol 13 (3) ◽  
pp. 434
Author(s):  
Ana del Águila ◽  
Dmitry S. Efremenko
Keyword(s):  
Radiative Transfer ◽  
Single Scattering ◽  
Atmospheric Composition ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Absorption Bands ◽  
Acceleration Techniques ◽  
Scattering Approximation ◽  
Fine Resolution ◽  
Single Scattering Approximation

Fast radiative transfer models (RTMs) are required to process a great amount of satellite-based atmospheric composition data. Specifically designed acceleration techniques can be incorporated in RTMs to simulate the reflected radiances with a fine spectral resolution, avoiding time-consuming computations on a fine resolution grid. In particular, in the cluster low-streams regression (CLSR) method, the computations on a fine resolution grid are performed by using the fast two-stream RTM, and then the spectra are corrected by using regression models between the two-stream and multi-stream RTMs. The performance enhancement due to such a scheme can be of about two orders of magnitude. In this paper, we consider a modification of the CLSR method (which is referred to as the double CLSR method), in which the single-scattering approximation is used for the computations on a fine resolution grid, while the two-stream spectra are computed by using the regression model between the two-stream RTM and the single-scattering approximation. Once the two-stream spectra are known, the CLSR method is applied the second time to restore the multi-stream spectra. Through a numerical analysis, it is shown that the double CLSR method yields an acceleration factor of about three orders of magnitude as compared to the reference multi-stream fine-resolution computations. The error of such an approach is below 0.05%. In addition, it is analysed how the CLSR method can be adopted for efficient computations for atmospheric scenarios containing aerosols. In particular, it is discussed how the precomputed data for clear sky conditions can be reused for computing the aerosol spectra in the framework of the CLSR method. The simulations are performed for the Hartley–Huggins, O2 A-, water vapour and CO2 weak absorption bands and five aerosol models from the optical properties of aerosols and clouds (OPAC) database.

Clinical experience of using virtual 3D modelling for pre and intraoperative guidance during robotic-assisted partial nephrectomy

2021 ◽  
pp. 205141582110002
Author(s):  
Lorenz Berger ◽  
Aziz Gulamhusein ◽  
Eoin Hyde ◽  
Matt Gibb ◽  
Teele Kuusk ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Partial Nephrectomy ◽  
Surgical Outcome ◽  
Prospective Cohort ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Robotic Assisted ◽  
Robotic Assisted Partial Nephrectomy

Objective: Surgical planning for robotic-assisted partial nephrectomy is widely performed using two-dimensional computed tomography images. It is unclear to what extent two-dimensional images fully simulate surgical anatomy and case complexity. To overcome these limitations, software has been developed to reconstruct three-dimensional models from computed tomography data. We present the results of a feasibility study, to explore the role and practicality of virtual three-dimensional modelling (by Innersight Labs) in the context of surgical utility for preoperative and intraoperative use, as well as improving patient involvement. Methods: A prospective study was conducted on patients undergoing robotic-assisted partial nephrectomy at our high volume kidney cancer centre. Approval from a research ethics committee was obtained. Patient demographics and tumour characteristics were collected. Surgical outcome measures were recorded. The value of the three-dimensional model to the surgeon and patient was assessed using a survey. The prospective cohort was compared against a retrospective cohort and cases were individually matched using RENAL (radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, location relative to polar lines) scores. Results: This study included 22 patients. Three-dimensional modelling was found to be safe for this prospective cohort and resulted in good surgical outcome measures. The mean (standard deviation) console time was 158.6 (35) min and warm ischaemia time was 17.3 (6.3) min. The median (interquartile range) estimated blood loss was 125 (50–237.5) ml. Two procedures were converted to radical nephrectomy due to the risk of positive margins during resection. The median (interquartile range) length of stay was 2 (2–3) days. No postoperative complications were noted and all patients had negative surgical margins. Patients reported improved understanding of their procedure using the three-dimensional model. Conclusion: This study shows the potential benefit of three-dimensional modelling technology with positive uptake from surgeons and patients. Benefits are improved perception of vascular anatomy and resection approach, and procedure understanding by patients. A randomised controlled trial is needed to evaluate the technology further. Level of evidence: 2b

Sight distance red zones on combined horizontal and sag vertical curves

1998 ◽  
Vol 25 (4) ◽  
pp. 621-630 ◽  
Author(s):  
Yasser Hassan ◽  
Said M Easa
Keyword(s):  
Quantitative Analysis ◽  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Horizontal Curve ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
Three Dimensional Models ◽  
Highway Alignment ◽  
Current Standards

Coordination of highway horizontal and vertical alignments is based on subjective guidelines in current standards. This paper presents a quantitative analysis of coordinating horizontal and sag vertical curves that are designed using two-dimensional standards. The locations where a horizontal curve should not be positioned relative to a sag vertical curve (called red zones) are identified. In the red zone, the available sight distance (computed using three-dimensional models) is less than the required sight distance. Two types of red zones, based on stopping sight distance (SSD) and preview sight distance (PVSD), are examined. The SSD red zone corresponds to the locations where an overlap between a horizontal curve and a sag vertical curve should be avoided because the three-dimensional sight distance will be less than the required SSD. The PVSD red zone corresponds to the locations where a horizontal curve should not start because drivers will not be able to perceive it and safely react to it. The SSD red zones exist for practical highway alignment parameters, and therefore designers should check the alignments for potential SSD red zones. The range of SSD red zones was found to depend on the different alignment parameters, especially the superelevation rate. On the other hand, the results showed that the PVSD red zones exist only for large values of the required PVSD, and therefore this type of red zones is not critical. This paper should be of particular interest to the highway designers and professionals concerned with highway safety.Key words: sight distance, red zone, combined alignment.

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