Geometric Modeling Process Research Articles

Analysis from the Functional Viewpoint of a Single-Cylinder Horizontal Steam Engine with a Crosshead Trunk Guide through Engineering Graphics

This paper explores a historical innovation created by Henry Muncaster: a stationary steam engine featuring a single-cylinder horizontal design with a crosshead trunk guide. Through the application of engineering graphics techniques, we have elucidated the functioning of this invention by developing a 3D CAD model based on the original drawings published in Model Engineer magazine in 1957. However, the geometric modeling process faced challenges due to missing and erroneous dimensions for several components. Consequently, dimensional, geometric, and movement constraints were applied to ensure the coherence and functionality of the 3D CAD model, alongside conducting an interference analysis. Ultimately, the proper alignment of the cylinder and crosshead was ascertained, which is crucial for maintaining uniform forces and motions within the steam engine. This alignment is pivotal for achieving balanced operation, minimizing vibrations, and enhancing the overall efficiency of the invention.

Engineering Drawing Applied to the Study of the Design of a Two-Cylinder Entablature Steam Engine with Parallel Motion Crosshead

This article presents an investigation into a historical invention consisting of a stationary steam engine designed by Henry Muncaster: a two-cylinder entablature steam engine with parallel motion crosshead. The present interdisciplinary research, based on the theoretical and methodological concepts of engineering drawing and computer-aided design, has allowed us to understand the operation of this invention from the 3D CAD model of the invention obtained thanks to the original drawings published in the magazine Model Engineer in 1957 and reproduced in 2017, since there is no descriptive information related to the invention. However, there have been drawbacks in the geometric modeling process since the dimensions of some components did not exist and in other cases they were erroneous. For this reason, dimensional, geometric and movement constraints (degrees of freedom) had to be applied so that said 3D CAD model would be coherent and functional, and an interference analysis also had to be performed. Finally, the existing symmetry in the arrangement of the cylinders and the crosshead has been discovered, it being essential to guarantee that the forces and movements are uniform on both sides of the steam engine, and allowing the work to be carried out in a more balanced manner by reducing vibrations and improving the overall efficiency of the invention.

A domain model for geometric modeling in support of the automated BIM modeling

PurposeThis research aims to argue that manual geometric modeling is blocking the building information modeling (BIM) promotion to small-size companies. Therefore, it is necessary to study a manner of automated modeling to reduce the dependence of BIM implementation on manpower. This paper aims to make a study into such a system to propose both its theory and prototype.Design/methodology/approachThis research took a prototyping as the methodology, which consists of three steps: (1) proposing a theoretical framework supporting automated geometric modeling process; (2) developing a prototype system based on the framework; (3) conducting a testing for the prototype system on its performance.FindingsPrevious researches into automated geometric modeling only respectively focused on a specific procedure for a particular engineering domain. No general model was abstracted to support generic geometric modeling. This paper, taking higher level of abstraction, proposed such a model that can describe general geometric modeling process to serve generic automated geometric modeling systems.Research limitations/implicationsThis paper focused on only geometric modeling, skipping non-geometric information of BIM. A complete BIM model consists of geometric and non-geometric data. Therefore, the method of combination of them is on the research agenda.Originality/valueThe model proposed by this paper provide a mechanism to translate engineering geometric objects into textual representations, being able to act as the kernel of generic automated geometric modeling systems, which are expected to boost BIM promotion in industry.

Left ventricular dimensions and mass measurement from 3D echocardiography: are we there yet?

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Health Research Council (HRC) of New Zealand and National Heart Foundation (NHF) of New Zealand Introduction—Echocardiographic measures of left ventricular (LV) structure and size, including LV wall thickness and LV end-diastolic dimension (LVID), provide important information in the assessment of patients with heart disease. For example, LV mass is a predictor of outcome for patients with hypertension and LVID is a predictor of cardiac resynchronisation response in patients with heart failure. Advances in 3D echocardiography (3DE) have enabled full-volume acquisitions, which overcome geometric assumptions present in conventional 2D echocardiography (2DE), providing a more accurate representation of cardiac geometry. Although numerous validation studies have been performed for 3DE-derived LV volumes, comparisons of LV dimension by 3DE against established methods are limited. Purpose—We sought to compare routine LV dimension measurements between 3DE and 2DE, with validation using cardiac magnetic resonance (CMR) imaging. Methods—Transthoracic echocardiography (2D and 3D) and cine CMR imaging were performed in 62 prospectively recruited participants (47 healthy controls, 9 patients with LVH, 6 patients with aortic regurgitation), <1 h apart. 2DE LV dimension measurements (interventricular septum [IVS], posterior wall thickness [PWT], and LVID) were taken at end-diastole from the parasternal long axis, and mass was calculated using the linear method based on ASE/EACVI guidelines. For 3DE, 3D geometric models of the LV were constructed by interactively fitting surfaces to the endocardium and epicardium using previously validated software, from which corresponding LV dimension measurements and mass were extracted. Measurements were obtained from CMR by a similar 3D geometric modelling process. Results—Differences (mean ± SD) in LV dimension measurements between the three modalities and intraclass correlation coefficients (ICC) are presented in Table I. When compared with CMR, 3DE exhibited higher agreement in terms of LVID and mass than 2DE, but lower agreement in wall thickness measurements. Statistically significant differences were found between 2DE and 3DE for PWT, LVID, and mass, as well as 2DE and CMR for LVID and mass (where P < 0.01 for a paired sample t­-test, marked with an asterisk). Meanwhile, there were no statistically significant differences between 3DE and CMR for IVS, PWT, LVID, or mass. Conclusions—Our results demonstrate that 3DE is superior to 2DE in terms of LVID and mass quantification, exhibiting good agreement with CMR. 3DE exhibited moderate and poor agreement for IVS and PWT, respectively, with both 2DE and CMR, likely due to the lower spatial resolution of 3DE. Further advances in 3DE image quality and analysis tools are therefore needed to improve accuracy of wall thickness measurements. Since 2DE imaging plane and probe positioning can result in oblique measurement and underestimation of LVID, the assessment of LVID and mass by 3DE is likely to lead to more accurate diagnostic and prognostic outcomes. Abstract Table 1

Geometric approach to machine exploitation efficiency : modelling and assessment

This article presents a new approach to the exploitation assessment of machines and devices. A key aspect of this approach is the construction of the assessment model based on the geometric representation of measures associated with each other, which covers the full specifics of the exploitation process. This approach is successfully implemented by the Overall Equipment Effectiveness (OEE) model, which is fully susceptible to the geometric modelling process due to the three-way system of assessed exploitation aspects. The result of this approach is the vectored OEE model and its interpretation in terms of time series of changes in values of components. Methods of determining vector calculus measures were developed, including the second-order tensor and gradient. This is the subject of the variability of the reliability conditions of machines or production processes. It allows for the realisation of an exploitation assessment based on dynamic changes in the values of their components in the time domain. This is a significant difference to the classical static approach to such an assessment. The developed new geometric OEE model was confirmed by verification tests using the LabView software, based on two parallel data sets obtained with analytical and simulation methods using the FlexSim software.

FROM LIDAR DATA TOWARDS HBIM FOR STRUCTURAL EVALUATION

Abstract. In HBIM processes, the extraction of geometric components from 3D point clouds data can sometimes be a complex process. The so-called Scan to BIM process has been widely utilized: deriving 3D models from point clouds often a local modelling of geometric components is necessary. This leads in most cases to use external modelling tools or complex local modelling processes. In both cases, we often get a model that cannot be reused for other items belonging to the same category, contravening the BIM philosophy. Vaulted systems are a typical example of complex elements that we can find in historical architecture. The paper presents the first results of an ongoing research on geometric modelling and structural evaluation of masonry ribbed vaults. An algorithm is developed to generate a NURBS surface of masonry vaults that, starting from the data extrapolated from the point cloud, allows to obtain an HBIM family. The research aims to overcome the inability to reference to standardised objects in local modelling of historical architecture elements. Directed to a standardization in the geometric modelling process of 3D laser scan data, the developed workflow is a possible alternative to commonly used workflows. Particular attention is focused on a case study of stellar vaults, a special class of masonry ribbed vaults whose three-dimensional geometry features a star-shaped projection on the horizontal plane. The work is carried out to verify that this family can be used for the structural analysis of stellar masonry vaults.

HBIM FOR ARCHAEOLOGICAL SITES: FROM SFM BASED SURVEY TO ALGORITHMIC MODELING

Abstract. The implementation of new technologies often leads research towards experimentation with new methodological approaches. The BIM process applied in cultural heritage is increasingly consolidating its practices, expanding its potential even in the field of archaeological research. Integrating archaeological data into BIM models has clear benefits but, due to the complexity of the involved elements, archaeological case studies can fit effectively into the BIM process only with the creation of semantic-aware libraries implementing dedicated objects. Cultural heritage can advantage of BIM-based knowledge management only integrating approaches and tools with different characteristics from those commonly used in BIM workflows. In the phase of the geometric modeling process, following that of the survey process and preparatory to the subsequent information modeling process, when the detected geometries are not easily traceable to libraries of pre-compiled objects, an alternative to the so-called "Scan to BIM" local modeling can be represented by algorithmic modeling. The paper, focusing on the geometric modelling phase of the HBIM process, presents first results and prospective tasks of an ongoing research project on the last architectural phase of the colonnade of a multilayered temple in the Antas valley in Sardinia (Italy), affected by imposing works of anastylosis and restoration.

Geometric Error Modeling of Parallel Manipulators Based on Conformal Geometric Algebra

An approach for geometric error modeling of parallel manipulators (PMs) based on the visual representation and direct calculation of conformal geometric algebra is introduced in this paper. In this method, the finite motion of an open-loop chain is firstly formulated. Through linearization of the finite motion, error propagation of the open-loop chain is analyzed. Then the error sources are separated in terms of joint perturbations and geometric errors. Next, motions and constraints of PMs are analyzed visually by their reciprocal property. Finally geometric error model of PMs are formulated considering the actuations and constraints. The merits of this new approach are twofold: (1) complete and continuous geometric error modeling can be achieved since finite motions are considered, (2) visual and analytical computation of motions and constraints are applied for transferring geometric errors from the open-loop chain to the PM. A 2-DoF rotational PM is applied to demonstrate the geometric error modeling process. Comparisons between simulation and analytical models show that this approach is highly effective.

Design of CASTonCAST shell structures based on load path network method

The CASTonCAST system consists in designing and producing architectural freeform shapes from precast stackable components. This allows fabricating and constructing curved shapes in concrete in an efficient and sustainable manner. Currently, the geometric modeling process of the system does not ensure that the shapes are load-bearing. This article introduces a method for the design of shell structures from stackable components based on the CASTonCAST system. In this research, the structural analysis is conducted using load path network method since this method helps integrating design, realization, and structural aspects.

A NOVEL METHOD FOR ESTIMATION OF GLACIER SURFACE MOTION IN 1960s FROM ARGON KH-5 OPTICAL IMAGERY

Abstract. The Antarctic ice sheet response to the global climate change, specifically the ice flow speed change of the glaciers, has been investigated by many researchers. However, most research results cover the period since 1970s or after the operation of the LANDSAT series. The availability of the film-based ARGON KH-5 data makes it possible to quantify the changes of the Antarctic ice sheet in 1960s. To meet the challenges of processing the low quality film-based ARGON images, a novel method was developed to allow estimating the ice sheet surface motion and reconstructing the surface model simultaneously from ARGON stereo images by decomposing the total parallaxes to terrain and motion based components. A photogrammetric approach was developed to distinguish stable ice surface features from those on motion and use them for recovering the camera orientation information. Several existing Antarctic mapping products were used to establish the ground control. The ice flow speed field is reconstructed using a hierarchical image matching strategy. Firstly, epipolar images are generated via a fundamental matrix derived from correspondences used in the geometric modelling process, and then an image pyramid is built. Second, the normalized cross-correlation (NCC) technique is conducted on each layer of the pyramid to match the extracted features. Since the images were taken at different times, during which the glacier motion occurred, the measured total parallaxes are decomposed to terrain and motion parallaxes according to given ice flow directions which are derived from the iteratively produced DTM or images. Finally, a speed map and a DTM can be generated at each level of the image pyramid. This process repeats itself. At the bottom of the pyramid the final speed map and DTM are produced at a resolution of about 60m and represent the ice flow field of 1963. This approach was tested using two ARGON stereo-pairs in Rayner glacier in East Antarctica. Both the ice flow speed map and DTM were generated, and their difference with recent products is briefly discussed.

A NOVEL METHOD FOR ESTIMATION OF GLACIER SURFACE MOTION IN 1960s FROM ARGON KH-5 OPTICAL IMAGERY

The Antarctic ice sheet response to the global climate change, specifically the ice flow speed change of the glaciers, has been investigated by many researchers. However, most research results cover the period since 1970s or after the operation of the LANDSAT series. The availability of the film-based ARGON KH-5 data makes it possible to quantify the changes of the Antarctic ice sheet in 1960s. To meet the challenges of processing the low quality film-based ARGON images, a novel method was developed to allow estimating the ice sheet surface motion and reconstructing the surface model simultaneously from ARGON stereo images by decomposing the total parallaxes to terrain and motion based components. A photogrammetric approach was developed to distinguish stable ice surface features from those on motion and use them for recovering the camera orientation information. Several existing Antarctic mapping products were used to establish the ground control. The ice flow speed field is reconstructed using a hierarchical image matching strategy. Firstly, epipolar images are generated via a fundamental matrix derived from correspondences used in the geometric modelling process, and then an image pyramid is built. Second, the normalized cross-correlation (NCC) technique is conducted on each layer of the pyramid to match the extracted features. Since the images were taken at different times, during which the glacier motion occurred, the measured total parallaxes are decomposed to terrain and motion parallaxes according to given ice flow directions which are derived from the iteratively produced DTM or images. Finally, a speed map and a DTM can be generated at each level of the image pyramid. This process repeats itself. At the bottom of the pyramid the final speed map and DTM are produced at a resolution of about 60m and represent the ice flow field of 1963. This approach was tested using two ARGON stereo-pairs in Rayner glacier in East Antarctica. Both the ice flow speed map and DTM were generated, and their difference with recent products is briefly discussed.

TOWARDS OBJECT DRIVEN FLOOR PLAN EXTRACTION FROM LASER POINT CLOUD

During the last years, the demand for indoor models has increased for various purposes. As a provisional step to proceed towards higher dimensional indoor models, powerful and flexible floor plans can be utilised. Therefore, several methods have been proposed that provide automatically generated floor plans from laser point clouds. The prevailing methodology seeks to attain semantic enhancement of a model (e.g. the identification and labelling of its components) built upon already reconstructed (a priori) geometry. In contrast, this paper demonstrates preliminary research on the possibility to directly incorporate semantic knowledge, which is itself derived from the raw data during the extraction, into the geometric modelling process. In this regard, we propose a new method to automatically extract floor plans from raw point clouds. It is based on a hierarchical space partitioning of the data, integrated with primitive selection actuated by object detection. First, planar primitives corresponding to vertical architectural structures are extracted using M-estimator SAmple and Consensus (MSAC). The set of the resulting line segments are refined by a selection process through a novel door detection algorithm, considering optimization of prior information and fitness to the data. The selected lines are used as hyperlines to partition the space into enclosed areas. Finally, a floor plan is extracted from these partitions by Minimum Description Length (MDL) hypothesis ranking. The algorithm is applied on a real mobile laser scanner dataset and the results are evaluated both in terms of door detection and consecutive floor plan extraction.

TOWARDS OBJECT DRIVEN FLOOR PLAN EXTRACTION FROM LASER POINT CLOUD

Abstract. During the last years, the demand for indoor models has increased for various purposes. As a provisional step to proceed towards higher dimensional indoor models, powerful and flexible floor plans can be utilised. Therefore, several methods have been proposed that provide automatically generated floor plans from laser point clouds. The prevailing methodology seeks to attain semantic enhancement of a model (e.g. the identification and labelling of its components) built upon already reconstructed (a priori) geometry. In contrast, this paper demonstrates preliminary research on the possibility to directly incorporate semantic knowledge, which is itself derived from the raw data during the extraction, into the geometric modelling process. In this regard, we propose a new method to automatically extract floor plans from raw point clouds. It is based on a hierarchical space partitioning of the data, integrated with primitive selection actuated by object detection. First, planar primitives corresponding to vertical architectural structures are extracted using M-estimator SAmple and Consensus (MSAC). The set of the resulting line segments are refined by a selection process through a novel door detection algorithm, considering optimization of prior information and fitness to the data. The selected lines are used as hyperlines to partition the space into enclosed areas. Finally, a floor plan is extracted from these partitions by Minimum Description Length (MDL) hypothesis ranking. The algorithm is applied on a real mobile laser scanner dataset and the results are evaluated both in terms of door detection and consecutive floor plan extraction.

Reverse geometric modeling for pre-form shape of prolate ellipsoid before hydro-forming

In order to form the needed prolate ellipsoidal shell with higher dimension accuracy, it is essential to develop an optimal pre-form shape before hydro-forming. A group of numerical simulation according to the optimal Latin hypercube design (Opt LHD) was first conducted on the combined prolate ellipsoidal shells, and the mathematical response models of axis lengths were developed. And then based on the adaptive simulated annealing algorithm, the reverse geometric modeling process was carried out and the possible pre-form shapes were given. Finally, an experimental verification was conducted to evaluate the reverse geometric modeling process, and the comparison between reverse design and experimental data was mainly discussed. It is shown that the dimension deviation between experiment and reverse design is less than 1 %. It is also experimentally proved that the needed prolate ellipsoidal shell can be formed by reversely designing an optimal pre-form shell.

Methodology to develop a geometric modeling process according to collaborative constraints

A product design goes through a Digital Mock-Up which is based on the product geometric model. This latter has an important role in the design project whose exploitation mainly depends on how it has been established (DELPHI Automotive Systems, Delphi met á plat ses arborescences, CADReport no. 192, février, 2004). Furthermore, the growing competitive context hardly encourages firms to implement new working methods like collaborative engineering. However, its implementation in combination with product geometric data generates many problems in terms of project and data management. For this purpose, this article proposes a methodological solution to the problem at hand. Moreover the problem gets complicated as the project progresses. As a result, the detailed design phase becomes critical particularly in the face of this problem. Therefore, the current article focuses on this phase of the product design process through an example.

자동차 프레스 패널 성형을 위한 드로 금형의 어덴덤 곡면 모델링

In the process of draw die design for stamping automotive press panels, the addendum surfaces generated in metal forming simulation software cannot be used in downstream processes such as machining and making draw dies because simulation tools use simple discrete models for the surface geometry. The downstream processes require more precise and continuous geometric models such as NURBS surfaces. Generally, automotive die engineers manually regenerate the addendum surface geometry using the discrete model. This paper presents an automated geometric modeling process for generating addendum surfaces using draft surface models. The design parameters of the section curve for the addendum surfaces are extracted automatically from the draft geometry. Using the extracted design parameters, smooth addendum surfaces are generated automatically as NURBS surfaces. The generated surfaces are <TEX>$G^1$</TEX> continuous with the part surface and the binder surface, and can be used in downstream processes.

Building Input File of MCNP 3D Model with Basic Graphics Exchange Specification

With the help of IGES standard file which was the exchange specification of initial graphics, different CAD system could change the data of product by neutral file’s format conversing. The automatic generation of 3D-Model curve surface in the MCNP input file was realized by using VC++ language.This method has solved the problem of the complication of MCNP geometric modeling process and the 3D-Model input problem in the MCNP. The input of MCNP was transferred the application problem of CAD/CAM software. The data and figure of varies software could be shared and converted. The work of design could be simple, the process of design could be speeded up and the cycle of design was shorted. Work efficiency and practicability were improved. If precision was controlled in 3D-Model, the result could be expected by contrast.

Study of Real Sense Terrain Generating Based on Fractal

In this paper, the overall designing idea on real terrain is firstly proposed, the geometric modeling process is introduced, BinSplit binary segmentation algorithm is put forward based on fractal theory and midpoint displacement algorithm idea. Then visualization of 3-D terrain based on OpenGL is accomplished; thus real sense terrain is generated and good result is gained.

A geometric modelling of boxgirder deck for integrated bridge design

This paper presents a geometric modelling of box girder deck to automate deck design representations. A geometric methodology was developed and implemented in a computer programme. This software allows the geometric description of the deck, using bridge design data usually given at the conceptual stage, and the automation of several drawings and 3-dimensional (3D) models, defined accurately. Using traditional graphical systems, the execution of deck specific drawings is extremely time consuming, the 3D deck model gives an approximation only of the exterior shape of the deck and the 3D finite elements (FE) mesh generation software imposes important simplifications on the deck configuration. The computer application provides an important tool to the bridge designer particularly at the conceptual stage, as it allows aesthetic and structural evaluation of the bridge at an early stage in the design. The geometric modelling process and graphical results of a case study are presented.

Geometric modeling of box girder deck for integrated bridge graphical system

This paper presents a geometric modeling of box girder deck to automate deck design representations. A geometric methodology was developed and implemented in a computer program. This software allows the geometric description of the deck, using bridge design data usually given at the conceptual stage, and the automation of several drawings and three-dimensional (3D) models, defined accurately. Using traditional graphical system, the execution of deck specific drawings is extremely time-consuming, the 3D deck model gives an approximation only of the exterior shape of the deck and the 3D finite elements (FE) mesh generation software imposes geometric simplifications on the real configuration of the deck before discretization. The computer application provides an important tool to the bridge designer, particularly at the conceptual stage, as it allows aesthetic and structural evaluation of the bridge at an early stage in the design. The geometric modeling process and graphical results of a case-study are presented.