High Detailed Model Research Articles

Investigation of concurrent multiscale topology optimization for designing lightweight macrostructure with high thermal conductivity

Lightweight and high heat conductive solid structures are playing important role in various fields of engineering. To maximize the design performance for such structures, we investigated multiscale topology optimization for excessive lightweight heat-conductive porous structures and introduced a mathematical optimization model formulation for concurrently optimizing the structures (macrostructure) and the constitutive pores (microstructure). The microscale is considered a representative volume element and designed using the asymptotic homogenization method. For each iteration, the effective heat conductivity tensor of the microstructure is evaluated during the optimization process and used as the heat conductivity of the macrostructure. Sensitivity analysis on this concurrent optimization scheme was derived to address the macro and microstructure coupling. To broaden the scope of the research applicability, three topology optimization methods, i.e., SIMP, level set and ESO are investigated, and the results are compared and discussed. The suggested formulations showed a successful application of the concurrent multiscale optimization formulations and good coupling on the macro and microscale. Also, the formulations demonstrated a strong influence between the macro and the microscale of the design problem for the topology optimization methods. Increasing the design freedom by introducing various microstructures for the macro design domain showed superior performance associated with attaining high weight reduction. In addition, the concurrent optimization scheme has enabled the microstructures to attain a good spatial layout of materials while taking into account the weight reduction constraint. The spatial arrangements of the designed microstructures have achieved conducting heat in a shorter path toward the heatsink zone of macrostructure design. This allows attaining good performance with high weight reduction. Furthermore, numerical examples of different mesh numbers were used to study mesh dependency of multiscale topology optimization. The scope of the study was broadened by the inclusion of 3D case studies. Implementing Isosurface technique to achieve high detail model was also used to attain high detailed concurrently optimized design with minimal mesh number to minimize the computational cost. The 3D optimized case was investigated experimentally.

Numerical investigation of the energy distribution of Low-intensity transcranial focused ultrasound neuromodulation for hippocampus

ObjectiveUltrasonic neuromodulation as a safe and non-invasive brain stimulation method that delivers a low-intensity, focused ultrasound to nervous system tissue in a targeted area of the brain. The objective of this study is to numerically investigate the ultrasound wave propagation and the energy distribution within the brain tissues using customized single element focused ultrasound transducers (SEFT), targeting the hippocampus. MethodsA high resolution detailed human head model with seven tissue types was constructed from magnetic resonance imaging (MRI). A full-wave finite-difference time-domain simulation platform, Sim4life, was then used to simulate a 3D non-linear ultrasound wave equation to the specific region of interest, the hippocampus. Three customized SEFT were used to test the effect of transducer positions, and another customized transducer was used to compare the sensitivity effect on heterogeneous and homogeneous brain models. Finally, the sensitivity and performance of low intensity focusing ultrasound stimulation were evaluated. ResultsAn optimized application of SEFT was customized to deliver 100 W/m2 intensity of energy deposition at the hippocampus region. About 85.65% of the generated volume beam was delivered to the targeted hippocampus region and the beam overlap parameter was affected by different transducer positions. Deflection angle changes of SEFT at the range of ± 5% did not have a significant effect on energy delivery and position displacement. Only 0.5% of peak pressure change was observed between heterogeneous and homogeneous brain models. The sensitivity analysis also showed that the sound speed is the most influential acoustic parameter. SignificanceThis study demonstrated that ultrasound neuromodulation targeting the depth brain tissue of the hippocampus could be a potential and promising alternative method to some non-acoustic brain stimulation modalities. In the numerical study of ultrasound brain stimulations, ultrasound parameters and the brain model need to be properly determined to simulate the ultrasonic neuromodulations.

5PM and DoC - Formal Models for Game Design

A formal language for game design is an endeavor many academics and industry personalities have been tackling since the mid-nineties. One of the most renowned formal models for game design, the MDA Framework, includes steps to delimit and conceptualize the experience with a top-down approach. There is, however, a significant lack of high detail models for mechanic construction as well as difficulty balancing.
 In this paper we propose two formal models for novice designers. The 5-Part-Model (5PM) for building and diagnosing game mechanics, and the Dimensions of Challenge (DoC) formal model for balancing and fine-tuning difficulty in games.

Effects of Topside Structures and Wind Profile on Wind Tunnel Testing of FPSO Vessel Models

This study examined the effects of wind loads on a floating production storage and offloading (FPSO) vessel, focusing in particular on the impact of the turbulent wind profiles, the level of details of the topside structures, and the operation modes of the gantry cranes. A series of wind tunnel tests were performed on the FPSO vessel model, developed with a scale of 1:200. It was observed that the wind loads measured using a low-detail model were often greater than those measured using a high-detail model. The measured wind loads corresponding to the Norwegian Maritime Directorate (NMD) profile with an exponent of 0.14, were approximately 19% greater than those corresponding to the Frøya profile in the entire range of wind directions, because of the slightly higher mean wind speeds of the NMD profile. The wind forces increased by up to 8.6% when the cranes were at operating mode compared to when they were at parking mode. In view of the observations made regarding the detail level of the tested models, a medium-level detail FPSO model can be considered adequate for the wind tunnel testing if a high-detail model is not available.

Towards efficient uncertainty quantification with high-resolution morphodynamic models: A multifidelity approach applied to channel sedimentation

To guarantee port accessibility, navigation approach channels need to be well maintained. Annual dredging efforts to maintain navigable channels may well exceed tens of millions m3 of sediment per year, which results in high recurrent costs for port operators. Quantification of expected siltation rates with process-based numerical models helps to effectively design and optimise approach channels. The setup of such models requires several assumptions and parameter settings which introduce uncertainty in model output. However, traditional Monte Carlo methods to quantify that uncertainty in model output are often too resource-intensive with current standard computer resources to be feasibly applied in coastal engineering projects such as approach channel design. Here, we use an alternative multifidelity approach to estimate the probability density function of channel siltation, at lower computational costs compared to direct Monte Carlo simulation. The idea behind this method is to map the output uncertainty of a faster, but inaccurate model to a preferred high-detailed model. The key requirement is that the faster, low-fidelity model and the detailed high-fidelity model are correlated, and that his correlation can be modelled with a probabilistic function. Since linearity of the correlation is not a requirement, the coarse-grid model can be very inaccurate but still serve as an adequate predictor of the high-fidelity model. In this study we did observe a highly nonlinear correlation, which in our case is explained by underestimation of channel siltation near the surf zone by the coarse model. In the presented multifidelity approach we adopted a combination of quasi-random Monte Carlo simulation and a non-parametric Gaussian process transfer function to estimate the uncertainty of total siltation and spatial patterns of siltation in a port approach channel. We argue that the multifidelity approach is conceptually straightforward and found that it can be used to significantly decrease the costs of probabilistic analysis; in our case we found a 85% decrease compared to direct Monte Carlo simulation. An additional advantage is that the approach allows for a trade-off between precision and efficiency by varying the number of high-fidelity model runs. Therefore, we conclude that the multifidelity framework is a potential powerful alternative for cases in which direct Monte Carlo simulation is infeasible or undesirable.

Computer Aided Design to Produce High-Detail Models through Low Cost Digital Fabrication for the Conservation of Aerospace Heritage

Aerospace heritage requires tools that allow its transfer and conservation beyond photographs and texts. The complexity of these engineering projects can be collected through digital graphic representation. Nevertheless, physical scale models provide additional information of high value when they involve full detailed information, for which the model in engineering was normally one more product of the manufacturing process, which entails a high cost. However, the standardization of digital fabrication allows the manufacture of high-detail models at low cost. For this reason, in this paper a case study of the graphic reengineering and planning stages for digital fabrication of a full-scale high-detail model (HDM) of the spatial instrument of the European Space Agency, named the Solar Orbiter mission Polarimetric and Helioseismic Imager (SO/PHI), is presented. After the analysis of this experience, seven stages of planning and graphic reengineering are proposed through collaborative work for the low cost digital manufacture of HDMs.

AN OPTIMISED WORKFLOW FOR THE INTERACTIVE EXPERIENCE WITH CULTURAL HERITAGE THROUGH REALITY-BASED 3D MODELS: CASES STUDY IN ARCHAEOLOGICAL AND URBAN COMPLEXES

Abstract. The paper compares two workflows for the achievement of 3D models aimed at in-depth studies on the geometric features of Cultural Heritage artefacts and their dissemination. The purpose is the outlining of pros and cons of different techniques coming from entertainment and video games industry, starting from highly reliable 3D documentation of cultural assets, i.e. architectural/archaeological/urban sites. Two different possible applications are described: (i) procedural modelling used for understanding and visualising reconstruction hypotheses of the vaulted pavilions at Hadrian’s Villa, Tivoli, Rome; (ii) optimisation of 3D high-detailed models, as input files, turned into visual reliable and highly portable assets for game-engines. The first case study is focussed on creating a flexible model for evalueting reconstruction hypotheses and supplying restorers with useful hints for shape completion of ruined pavilions. The second case study makes available detailed digital contents for storytelling historical and cultural events in an attractive way, as in the case of the urban explorative model of Chiuro, a small town in northern Italy.

RECREATING CULTURAL HERITAGE ENVIRONMENTS FOR VR USING PHOTOGRAMMETRY

Abstract. In this paper, we propose a workflow for recreating places of cultural heritage in Virtual Reality (VR) using structure from motion (SfM) photogrammetry. The unique texture of heritage places makes them ideal for full photogrammetric capture. An optimized model is created from the photogrammetric data so that it is small enough to render in a real-time environment. The optimized model, combined with mesh maps (texture maps, normal maps, etc.) looks like the original high detail model. The capture of a whole space makes it possible to create a VR experience with six degrees of freedom (6DoF) that allows the user to explore the historic place. Creating these experiences can bring people to cultural heritage that is either endangered or too remote for some people to access. The workflow described in this paper will be demonstrated with the case study of Myin-pya-gu, an 11th century temple in Bagan, Myanmar.

A Feedback Simulation Procedure for Real-time Control of Urban Drainage Systems

Abstract This paper presents a feedback simulation procedure for the real-time control (RTC) of urban drainage systems (UDS) with the aim of providing accurate state evolutions to the RTC optimizer as well as illustrating the optimization performance in a virtual reality. Model predictive control (MPC) has been implemented to generate optimal solutions for the multiple objectives of UDS using a simplified conceptual model. A high-fidelity simulator Info Works ICM is used to carry on the simulation based on a high level detailed model of a UDS. Communication between optimizer and simulator is realized in a feedback manner, from which both the state dynamics and the optimal solutions have been implemented through realistic demonstrations. In order to validate the proposed procedure, a real pilot based on Badalona UDS has been applied as the case study.

Image-based techniques for the survey of mosaics in the St Mark's Basilica in Venice

<p>This article aims to critically examine the entire methodology of very large scale (1:1) surveying and documentation of mosaic surfaces. The term ‘survey’ should be read in its broadest and most complete and sense, including the phases of measurement and data processing as well as management and use of these data for the purposes of preservation and maintenance. The case study presented here took place at St Mark’s Basilica (<em>Basilica di San Marco</em>), in Venice, where mosaic flooring, wall and vault decorations have been surveyed on two separate occasions. These two experiences shared a common goal (a full-scale survey of the mosaic decorations) but differed in terms of the methodologies used, chiefly due to the technological developments of recent years. All this, therefore, lends itself to a methodological reflection and critique of the ways in which surveying technology has evolved over time. It enables to conduct surveys that would, just a few years ago, have been inconceivable due to their size and complexity. This article describes in detail current surveying processes, which includes the use of a multi-scale “image-based” approach, “re-topology” methods such as non-uniform rational B-spline (NURBS) and a tailor-made Building Information Modeling (BIM) system. This system allows the direct use of a three-dimensional (3D) model of the Basilica within the maintenance process of the monument itself with the options to georeferencing information, extract basic metric data and catalogue all its mosaics.</p><p><strong>Highlights:</strong></p><ul><li><p>Modern digital photogrammetric techniques enable the acquisition of very complex objects, not only in terms of form but also in terms of material.</p></li><li><p>To obtain high resolution orthophotos, it is necessary to accurately take care of all the stages of the process: photographic acquisition, surveying, modelling and orthographic reprojection.</p></li><li><p>High resolution images and detailed 3D models can benefit from a complex BIM system for the management of all data.</p></li></ul>

Modular Multilevel Converter for Wind Energy Storage Applications

This paper presents a medium-voltage wind energy conversion system with integrated storage that implements power electronics converter based on modular multilevel topology. The proposed converter has a storage system integrated into its modular cell structure. This paper analyzes the proposed topology and presents detail sizing procedure for both converter and storage system in order to meet new grid connection standards and fault ride through (FRT) requirements. In order to verify the system operation, high detail model of the converter leg is used to simulate independent power control on ac and dc sides of the converter needed for the successful implementation of the FRT control.

High temperature shock tube experiments and kinetic modeling study of diisopropyl ketone ignition and pyrolysis

Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. In this work, a high temperature detailed combustion kinetic model for DIPK was developed using the reaction class approach. DIPK ignition and pyrolysis experiments were performed using the UCF shock tube. The shock tube oxidation experiments were conducted between 1093K and 1630K for different reactant compositions, equivalence ratios (φ=0.5–2.0), and pressures (1–6atm). In addition, methane concentration time-histories were measured during 2% DIPK pyrolysis in argon using cw laser absorption near 3400nm at temperatures between 1300 and 1400K near 1atm. To the best of our knowledge, current ignition delay times (above 1050K) and methane time histories are the first such experiments performed in DIPK at high temperatures. Present data were used as validation targets for the new kinetic model and simulation results showed fair agreement compared to the experiments. The reaction rates corresponding to the main consumption pathways of DIPK were found to have high sensitivity in controlling the reactivity, so these were adjusted to attain better agreement between the simulation and experimental data. A correlation was developed based on the experimental data to predict the ignition delay times using the temperature, pressure, fuel concentration and oxygen concentration.

Tool path generation on doubly-curved free-form surfaces

ABSTRACTIn the industries of automobiles and aerospace, the use of carbon fiber has grown exponentially over the years due to its high specific mechanical properties. However, the existing processes for the placement of these fibers within these industries remain either restrictive to the doubly-curved free-formed surfaces required or economically unfeasible in respect to the larger scaled components desired. This paper presents a tool path generation process which will produce non-collisional pathing for the automated placement of uniform fibers on scalable doubly-curved free-formed surfaces. To begin this process, a high detail model of the component part is given and analyzed for optimizing the placement of both the part and the KUKA robot. We account for variable fiber placement angles based on design specifications of the part. The process will begin with a given three-dimensional rendering of the component model which will be transformed into a readable Robotic Scripting Language (RSL) file that the...

An Interactive Tool for Automatic Predimensioning and Numerical Modeling of Arch Dams

The construction of double-curvature arch dams is an attractive solution from an economic viewpoint due to the reduced volume of concrete necessary for their construction as compared to conventional gravity dams. Due to their complex geometry, many criteria have arisen for their design. However, the most widespread methods are based on recommendations of traditional technical documents without taking into account the possibilities of computer-aided design. In this paper, an innovative software tool to design FEM models of double-curvature arch dams is presented. Several capabilities are allowed: simplified geometry creation (interesting for academic purposes), preliminary geometrical design, high-detailed model construction, and stochastic calculation performance (introducing uncertainty associated with material properties and other parameters). This paper specially focuses on geometrical issues describing the functionalities of the tool and the fundamentals of the design procedure with regard to the following aspects: topography, reference cylinder, excavation depth, crown cantilever thickness and curvature, horizontal arch curvature, excavation and concrete mass volume, and additional elements such as joints or spillways. Examples of application on two Spanish dams are presented and the results obtained analyzed.

Silvicolous on a small scale: possibilities and limitations of habitat suitability models for small, elusive mammals in conservation management and landscape planning.

Species distribution and endangerment can be assessed by habitat-suitability modelling. This study addresses methodical aspects of habitat suitability modelling and includes an application example in actual species conservation and landscape planning. Models using species presence-absence data are preferable to presence-only models. In contrast to species presence data, absences are rarely recorded. Therefore, many studies generate pseudo-absence data for modelling. However, in this study model quality was higher with null samples collected in the field. Next to species data the choice of landscape data is crucial for suitability modelling. Landscape data with high resolution and ecological relevance for the study species improve model reliability and quality for small elusive mammals like Muscardinus avellanarius. For large scale assessment of species distribution, models with low-detailed data are sufficient. For regional site-specific conservation issues like a conflict-free site for new wind turbines, high-detailed regional models are needed. Even though the overlap with optimally suitable habitat for M. avellanarius was low, the installation of wind plants can pose a threat due to habitat loss and fragmentation. To conclude, modellers should clearly state the purpose of their models and choose the according level of detail for species and environmental data.

Modeling CO emission from hydrodynamic simulations of nearby spirals, starbursting mergers, and high-redshift galaxies

We model the intensity of emission lines from the CO molecule, based on hydrodynamic simulations of spirals, mergers, and high-redshift galaxies with very high resolutions (3pc and 10^3 Msun) and detailed models for the phase-space structure of the interstellar gas including shock heating, stellar feedback processes and galactic winds. The simulations are analyzed with a Large Velocity Gradient (LVG) model to compute the local emission in various molecular lines in each resolution element, radiation transfer and opacity effects, and the intensity emerging from galaxies, to generate synthetic spectra for various transitions of the CO molecule. This model reproduces the known properties of CO spectra and CO-to-H2 conversion factors in nearby spirals and starbursting major mergers. The high excitation of CO lines in mergers is dominated by an excess of high-density gas, and the high turbulent velocities and compression that create this dense gas excess result in broad linewidths and low CO intensity-to-H2 mass ratios. When applied to high-redshift gas-rich disks galaxies, the same model predicts that their CO-to-H2 conversion factor is almost as high as in nearby spirals, and much higher than in starbursting mergers. High-redshift disk galaxies contain giant star-forming clumps that host a high-excitation component associated to gas warmed by the spatially-concentrated stellar feedback sources, although CO(1-0) to CO(3-2) emission is overall dominated by low-excitation gas around the densest clumps. These results overall highlight a strong dependence of CO excitation and the CO-to-H2 conversion factor on galaxy type, even at similar star formation rates or densities. The underlying processes are driven by the interstellar medium structure and turbulence and its response to stellar feedback, which depend on global galaxy structure and in turn impact the CO emission properties.

Tyre–road grip coefficient assessment – Part II: online estimation using instrumented vehicle, extended Kalman filter, and neural network

The main objective of this work is to determine the limit of safe driving conditions by identifying the maximal friction coefficient in a real vehicle. The study will focus on finding a method to determine this limit before reaching the skid, which is valuable information in the context of traffic safety. Since it is not possible to measure the friction coefficient directly, it will be estimated using the appropriate tools in order to get the most accurate information. A real vehicle is instrumented to collect information of general kinematics and steering tie-rod forces. A real-time algorithm is developed to estimate forces and aligning torque in the tyres using an extended Kalman filter and neural networks techniques. The methodology is based on determining the aligning torque; this variable allows evaluation of the behaviour of the tyre. It transmits interesting information from the tyre–road contact and can be used to predict the maximal tyre grip and safety margin. The maximal grip coefficient is estimated according to a knowledge base, extracted from computer simulation of a high detailed three-dimensional model, using Adams® software. The proposed methodology is validated and applied to real driving conditions, in which maximal grip and safety margin are properly estimated.

Design analysis and sizing of a circulation controlled CFRP wing with Coandǎ flaps via CFD–CSM coupling

Preliminary design tools are essential during aircraft design to make conclusions about an aircraft’s performance. Generally this process employs methods of low and medium fidelity to create comparatively fast results for a high number of parameter variations. High-fidelity methods are needed to verify theses results and to consider components in more detail. A 100 PAX commercial aircraft with short take-off and landing capabilities of 800 m with circulation controlled high-lift devices is under investigation at the Collaborative Research Centre SFB 880. In this paper, a global wing analysis with a high detail model is conducted and the results are compared with results attained with a preliminary aircraft design tool. Several detailed designs for the air feed system integration are proposed and examined regarding weight and stiffness characteristics on a representative high-lift device section model. Fluid–structure coupling is employed during all analyses to transfer aerodynamic loads and structural displacements. The aeroelastic impact of the slot stiffness on the Coandǎ effect during landing is then quantified. The attained aerodynamic performance results and structural characteristics of each configuration are compared and the advantages are discussed.

Cost-effectiveness of habitat-suitability maps using low-detailed data for elusive bat species

European bat species are strictly protected by law, and the Member States of the European Union are obliged to record species condition and to contribute to their conservation. Habitat-suitability models are an essential aid in assessing the conservation status and distribution of a species. However, model performance depends on the data quality. This study compares habitat-suitability models that were generated from two data sets that differ in the degree of details included. The first model used data that were low in detail but freely available and the second used data that were very detailed but costly. Three hypotheses were addressed: (1) that the model using low-detailed data is sufficient in its performance to aid the assessment of species distribution and infrastructural planning; (2) the visualisation of actual species distribution is more accurate in the high-detailed model; and (3) habitat-suitability maps can depict species distribution better than species occurrence data alone. To develop models, climate, geographic and roosting data of Myotis bechsteinii were used. Models allowed very good spatial predictions of suitable habitats. However, the model using low-detailed data overestimated suitable habitat. The high-detailed model was more able to predict actual species distribution. These findings were supported by field evaluation where M. bechsteinii could only be detected in areas where both models predicted high habitat suitability. This framework is promising as it resulted in spatially explicit habitat-suitability maps and suggests that similar models may be used to improve the understanding of bat distribution and factors endangering other species of bats.

3D Models Simplification Algorithm for Mobile Devices

As we know, the mobile device screen is small. The lower accuracy of the model is relatively weak and the capacity to handle high detailed model is very limited. What’s more, the existing three-dimensional simplification algorithms are for the personal computer and they are not suitable for the mobile terminals. Thus, we propose a novel 3D model simplification algorithm based on feature points. We will find the model surface curvature of each vertex, based on the model feature points. For these points, we present a new method to obtain it. Experimental results show that the algorithm can accurately reflect the model changes of the local surface geometry, and effectively keep the details of the model characteristics.