Geometric modeling and processing

Background/Objectives: One of the most serious complications following implant placement in the atrophic posterior mandible is injury to the inferior alveolar nerve (IAN), which can also happen during occlusal loading of the implants. This study investigates the effects of 4 mm implant stress transmission to the inferior alveolar nerve during occlusal loading in cases of severe posterior mandibular atrophy. Methods: The computer-aided design (CAD) model was created and modified through Direct Modeling techniques. The structure of cortical and trabecular bones was simplified, and it was modeled as a cylinder block. Finite element analysis (FEA) was carried out in 3D to investigate the pressure distribution over the IAN at different implant-to-nerve distances (1.5 mm, 0.5 mm, and 0.1 mm), and stress and strain deformations were simulated in the mandibular model. Results: The results of the pressure analysis on the inferior alveolar nerve indicate that the pressure distribution at different implant-to-nerve distances (1.5 mm, 0.5 mm, and 0.1 mm) is consistently below 0.026 MPa, which corresponds to the maximum pressure range that may block nerve impulses. This occurs even at the theoretical and simulated distance of 0.1 mm, suggesting that cortical bone stiffness plays a crucial role in mitigating stress at reduced implant-to-nerve proximities. Conclusions: Within the limits of this study, ultra-short implants can be placed even less than 0.5 mm (up to 0.1 mm under the 3D-FEA hypothesis) above the inferior alveolar nerve under the 3D-FEA hypothesis, while maintaining pressure below the threshold value. This is due to the rigidity of the cortical bone, which helps to reduce pressure transmission to the nerve.

Keywords: CAD direct modeling , dental implant , finite element analysis , inferior alveolar nerve , nerve injury , short implant

CAD assembly models are typically represented as a collection of components, each of which can share geometric interfaces with others. In the literature, geometric interfaces have been shown to play a fundamental role in assembly model analysis, component characterization, and classification. While these interfaces are not explicitly defined in CAD models, they can be inferred from the relative positioning of components. The resulting geometric interfaces can be categorized as either interference or contact. However, it is often unclear whether these interfaces stem from intentional design choices related to component shape and function, from consistently applied relative positioning, or from unintended errors. In industrial practice, the design of complex products often involves models sourced from public catalogs for third-party components. These catalog models frequently include shape simplifications, which can lead to unintended intersections or clearances with surrounding components — deviations that do not exist in the final physical product. This study aims to provide a comprehensive analysis and formalization of geometric interfaces, based on the complementary roles of CAD assembly modules and digital component catalogs, both widely used in industry as foundational resources for generating assembly models. The results are directly applicable to industrial CAD assembly models and can serve as a reference for CAD developers seeking to improve and extend assembly processing, as well as for researchers conducting assembly analysis. This work introduces a formalization of geometric interfaces, including contacts, interferences, and interface envelopes, which are essential for defining component mounting requirements. An analysis of geometric interface perturbations caused by repetition operators is performed, leading to the concept of an interface envelope to model specific interface repetitions.

Keywords: Assembly , Component digital catalog , Component representation , Geometric constraints , Geometric modeler tolerance , Interface envelope , Interfaces , Symmetry properties

Background and objective: Despite the availability of several commercial solutions for predicting the soft tissue outcomes of maxillofacial surgeries, none have proven sufficiently reliable for routine clinical use. This study proposes a 3D methodology for predicting soft tissue displacement following maxillofacial surgery without relying on mechanical modeling, unlike most existing approaches. Methods: Pre- and post-operative Cone Beam Computed Tomography scans of patients with class III malocclusion were collected. Tailored image processing and volume reconstruction techniques were applied to semi-automatically generate 3D soft tissue models. Cephalometric landmarks were identified to perform a geometrical similarity analysis among patients with the same malocclusion class undergoing the same surgical procedure. Vectorial displacement maps were generated to capture the soft tissue changes from pre- to post-operative and were then applied to the pre-operative of test patients to predict soft tissue outcomes. Euclidean distances were calculated between predicted and real post-operative positions, and the Wilcoxon signed-rank test was conducted to assess statistical differences between predicted and real landmark coordinates. Results: Error maps indicated that approximately 70 % of predicted facial points had errors below 2.5 mm, while around 10 % ranged between 2.5 mm and 3 mm. Statistically significant differences (p < 0.05) were observed only for the gonion and cheilion. Conclusion:. The findings support the validity of the geometrical similarity analysis and the vectorial displacement map approach. The simplicity and promising accuracy of the proposed method encourage further investigations across different surgical procedures. Additionally, integrating this methodology into surgical planning could offer a viable alternative to commercial solutions.

Keywords: 3D soft tissue prediction , Dental malocclusion , Displacement vectorial map , Orthognathic surgery , Soft tissue displacement

The Divertor Tokamak Test (DTT) project represents a significant milestone in the pursuit of sustainable and efficient nuclear fusion energy. As for any other nuclear fusion experimental machine, the design of DTT components deals with several challenges due to the harsh environment, the demanding mechanical loads and a number of competing requirements. In this context, correctly establishing, from the early design stage, an efficient methodology for parametric design and optimization is of paramount importance. This paper discusses a Systems Engineering approach applied to the design of the DTT divertor cassette, based on a CAD-centric methodology and using an iterative automated workflow implemented in the software modeFRONTIER and VOLTA. The workflow starts from the creation of a parametric model of the divertor geometry, where key dimensional parameters (e.g., dimensions, angles, shapes) are defined as variables that can be adjusted within specified ranges. The design objectives and constraints have been identified, involving mainly structural but also thermal and fluid dynamic aspects. The design space has been explored by modifying the set of driving parameters, therefore, the divertor geometry has been iteratively changed. All the probed geometries have been analysed through FE method. In the performed simulations the EM loads due to a major Downward Vertical Displacement Event have been set up. The whole optimization process has been implemented through VOLTA which is an integration platform for multi-objective and multi-disciplinary optimization. It provides a seamless coupling with third party engineering tools, enabling the automation of the design simulation process, and facilitating analytic decision making. VOLTA integrates with any parametric software (CAD, CAE, FEM, generic, etc.) automating the entire optimization process in which data is transferred from one simulation to the next and the relevant values of outputs and objectives are extracted. The optimization is multi-objective, so the choice of the best design is not immediate. In order to simplify this choice, some tools provided by VOLTA are used.

Keywords: Divertor , DTT , FEA , Optimization

A feasibility study of a new testing facility, i.e. the volumetric neutron source, VNS, in a tokamak configuration was initiated in 2023 and it is now under way with the purpose of addressing potential showstoppers. Key outcomes of the engineering activities are presented at this conference. The main goal of the VNS is to provide a realistic environment to test the in-vessel components of fusion reactors, in particular the tritium breeding blanket. The lessons learned during previous years of DEMO development point to the need for a thorough nuclear design integration already at level of the basic machine design, hence the issues related to the maintenance of the in-vessel components have been addressed at a basic level. The work presented here describes the remote maintenance strategy for VNS blankets, which is an adaptation of the concept proposed for DEMO.

Keywords: CAD , Design integration , Remote maintenance , Shielding blanket , Volumetric neutron sources

The development of a remote maintenance strategy for the replacement of the in-vessel components of the DEMO reactor is one of the key issues on the path to the realization of fusion energy. A critical aspect is the maintenance of the service pipes that supply coolant and remove the tritium that is bred in the Breeding Blankets (BB). Pipe service technologies are available from industrial applications and specific ITER developments, but these are not fully compliant with the requirements and pipe sizes defined for DEMO. In order to carry out the maintenance of the in-situ pipelines foreseen in DEMO, it is sometimes necessary, due to space constraints, to use equipment that operates from inside the pipelines for both cutting and welding, known as in-bore tools. This article is focused on the development of the in-bore welding tool for the large DN200 cooling pipes of the water-cooled BB. A stepwise approach was adopted: 1) Identification of the maintenance strategy and tool requirements. 2) Realization of a prototype with the purpose of demonstrating principal functions. This prototype has been a key step to validate the solution achieved and/or to address issues that arose during the project, highlighting any potential problems. 3) Preliminary design of the in-bore welding tool for DN200 pipes, followed by a first prototype in full scale to test key functions, including the clamping system inside the pipe. The prototype has been realized through additive manufacturing.

Keywords: CAD , DEMO , FEM , In-bore welding tool , Remote maintenance

This study presents a methodology for optimizing the design of the fossa component in temporomandibular joint (TMJ) prostheses, particularly in cases requiring replacement due to severe pathology or trauma. Leveraging advancements in 3D printing, the research aims to align prosthetic function with natural jaw movements. A multibody simulation model was used to evaluate different designs based on key performance indicators: range of motion, condylar trajectory accuracy, and contact force magnitudes. Three designs were analyzed: a compact design fossa (CDF) with a spherical condyle, an enhanced design fossa (EDF) with a more anatomically realistic structure, and a simulation-driven design (MEDF) derived from condylar motion patterns. The results indicate that CDF could lead to dislocation at 13° of mouth opening. In contrast, EDF and MEDF safely enabled full opening (20°), closely replicated natural condyle trajectories (with deviations under 2.5 mm in all directions), and reduced contact forces, which can contribute to a longer prosthesis lifespan. MEDF showed the lowest peak contact force (−21% compared to EDF). The study successfully established a framework for evaluating and guiding patient-specific TMJ prosthetic designs, enhancing both functional rehabilitation and mechanical durability by minimizing wear through optimized contact dynamics.

Keywords: CAD , mandible kinematics , motion tracking , multibody model , patient-specific design , range of motion , TMJ prosthesis

In the modern industrial and robotics landscape, the demand for customized, high-performance solutions is increasing, posing challenges in reducing design and development times while ensuring product quality. Traditional approaches relying on physical prototypes are expensive, time-consuming, and often inadequate for addressing the growing system complexity. Virtual Prototyping (VP) offers an alternative, enabling analysis, simulation, and optimization of product performance in a virtual environment before physical implementation. This paper focuses on collaborative robotics, where different tools can effectively simulate specific aspects of robotic system design. However, a lack of an integrated framework that seamlessly combines Computer-Aided Design, multibody modelling, and requirement verification still represents a gap. To address this, a Virtual Prototyping framework for robotic system design and verification is proposed. It begins with system requirements elicitation to ensure that the virtual models are fully aligned with the stakeholder needs. By focusing on the components and interactions required to verify the defined requirements, the approach allows consistency and avoids unnecessary complexity. CAD models support visualization and analysis of physical configurations, while multibody modelling enables simulations to verify functional requirements. A case study demonstrates the framework's effectiveness through the development of an Autonomous Mobile Cobot by integrating two pre-existing robotic systems. The approach ensures requirement coherence while significantly reducing development time and cost.

Keywords: CAD , Human-robot collaboration , Multibody modelling , Virtual Prototyping

CAD assembly models are typically represented as a collection of components, each of which can share geometric interfaces with others. In the literature, geometric interfaces have been shown to play a fundamental role in assembly model analysis, component characterization, and classification. While these interfaces are not explicitly defined in CAD models, they can be inferred from the relative positioning of components. The resulting geometric interfaces can be categorized as either interference or contact. However, it is often unclear whether these interfaces stem from intentional design choices related to component shape and function, from consistently applied relative positioning, or from unintended errors. In industrial practice, the design of complex products often involves models sourced from public catalogs for third-party components. These catalog models frequently include shape simplifications, which can lead to unintended intersections or clearances with surrounding components — deviations that do not exist in the final physical product. This study aims to provide a comprehensive analysis and formalization of geometric interfaces, based on the complementary roles of CAD assembly modules and digital component catalogs, both widely used in industry as foundational resources for generating assembly models. The results are directly applicable to industrial CAD assembly models and can serve as a reference for CAD developers seeking to improve and extend assembly processing, as well as for researchers conducting assembly analysis. This work introduces a formalization of geometric interfaces, including contacts, interferences, and interface envelopes, which are essential for defining component mounting requirements. An analysis of geometric interface perturbations caused by repetition operators is performed, leading to the concept of an interface envelope to model specific interface repetitions.

Keywords: Assembly , Component digital catalog , Component representation , Geometric constraints , Geometric modeler tolerance , Interface envelope , Interfaces , Symmetry properties

Anterior cruciate ligament reconstruction (ACL-R) has a high success rate, but a subset of patients report unsatisfactory outcomes, highlighting the need for improved predictive tools. Recent studies have shown that bony morphology plays an important role in both the risk of ACL injury and post-reconstruction outcomes. This study aims to develop a framework for understanding the relationship between morphology and patient satisfaction. We explore the use of machine learning (ML) models to predict patient satisfaction following ACL reconstruction based on preoperative bone morphology. Using 3D models from high-resolution Magnetic Resonance (MR) imaging, 21 morphological parameters of the femur and tibia were analysed, including linear, surface and volumetric measurements. These were correlated with patient satisfaction as assessed by the Knee injury and Osteoarthritis Outcome Score Global (KOOS Global) questionnaire, administered six months after surgery. To streamline the analysis, automated systems based on statistical shape models and deep learning were employed for landmark placement and segmentation. A dataset of 45 patients was used to train and evaluate three ML models: Random Forest, Logistic Regression and Gradient Boosting. Dimensionality reduction identified 10 key morphological features and Gradient Boosting outperformed the other models, achieving accuracy of 0.89, precision of 0.90 and recall of 0.89. The results demonstrate the potential of combining advanced imaging, automated measurement and ML for personalized prediction of patient satisfaction. The predictive model shows that primarily femoral features, along with intercondylar notch volume and tibial measurements, play a critical role in determining patient satisfaction. This approach may guide surgical planning, patient counselling, intervention strategies and rehabilitation. Although promising, further research with larger datasets, additional parameters and advanced ML techniques is needed to improve model robustness and clinical applicability.

Keywords: 3D modeling , Anterior cruciate ligament , Machine learning , Morphology , Prediction

Porous media have been demonstrated to be efficient heat transfer surfaces but they must be optimized for any given applications. In this regard, numerical simulations can improve the analyses of heat transfer and fluid flow in porous media, making their design and optimization faster, cheaper, and more reliable. Unfortunately, implementing detailed numerical simulations of stochastic foams is challenging because the geometry of a commercially available foam is usually randomly generated and must be reconstructed with cumbersome and expensive methods, like X-ray tomography. Vice versa, the use of a perfectly known geometry can be very helpful for improving the reliability, consistency and robustness of the numerical analyses. This work demonstrates that it is possible to design from scratch a stochastic open-cell foam using computational geometry algorithms and fabricate it by additive manufacturing. In fact, in the present study, a foam was designed and 3D printed, before being tested and numerically analyzed. When tested, the designed foam performed exactly the same as compared to traditional foam but being the geometry completely known, it was possible to run a direct simulation, opening, for the first time, the opportunity to optimize the thermo-fluid behavior of the porous media. After model validation, foams with the same porosity but different pore density were then numerically simulated, monitoring the corresponding pressure drops.

Keywords: Additive manufacturing , Cellular solids , Experimental test , Foam numerical simulation , Lattice structures , Open-cell foam , Pressure drop

Featured Application: The work finds potential application in the design and manufacture of patient-specific scaffolds in the biomedical field using desktop MEX AM technologies. The design of scaffolds and prostheses benefits from the opportunities provided by additive manufacturing technologies. Specifically, scaffold design using cellular structures based on lattices has become a significant focus. These lattice-based scaffolds exhibit intricate and complex shapes with controlled macro-porosity. In this study, a method is presented that enables the modeling of a graded-density lattice structure for material extrusion additive manufacturing, without relying on a geometric lattice model. The methodology utilizes computed tomography (CT) scans as inputs to obtaining a 3D scalar field and a surface model. The lattice structure is designed and generated within the computer-aided manufacturing (CAM) software, ensuring consistent machine toolpaths. The 3D scalar field, representing a relative density map derived from CT Hounsfield units, drives the variation of the extrusion parameters generated by the CAM, achieving a graded-density lattice.

Keywords: additive manufacturing , computed tomography , functionally graded lattice structures , fused filament fabrication , graded lattices , volumetric modeling

Oscillating Water Column (OWC) devices are a promising technology for harnessing wave energy, utilizing the movement of seawater induced by waves. OWC systems offer renewable energy solutions with minimal environmental impact. The Power Take-Off (PTO) system, crucial for converting pneumatic power into usable energy like electricity, is central to their functionality. This study investigates using a ducted Savonius turbine as the PTO system in an OWC setup. Experimental tests were conducted on a scaled Savonius turbine to assess the turbine efficiency. A CAD model of the setup was created and imported into a Computational Fluid Dynamics (CFD) environment for detailed fluid dynamic analysis, utilizing the Sliding Mesh combined with the Dynamic Fluid Body Interaction (DFBI) technique to simulate turbine motion. Validation of the CFD model was achieved by comparing numerical results with experimental data. A fifth-order Bell-Metha polynomial profile power augmenter was considered to enhance turbine performance by increasing the rotational speed and reducing resistance. This strategy aims to minimize energy loss and operational disturbances by targeting vortex reduction upstream of the turbine. With the validated setup, power augmenters were introduced and a parametric analysis was performed to assess turbine efficiency, using the coefficients of the Bell-Metha profile as parameters. The results were promising for future development in wave energy conversion technology.

Keywords: CFD , OWC , Parametric analysis , Savonius turbine

The maritime sector faces an ecological revolution. In addition to the use of green propulsion systems and reducing the environmental impact of non-recyclable parts, global performance enhancement of the vessels is essential to this change. Hydrofoils are one of the technologies that is significantly impacting this shift: using wings under the hull, may significantly decrease drag and, in the case of powered boats, emissions. Similar to aircraft, the design of hydrofoil wings entails a process that adjusts parameters such as attack angles, profile types, and overall wing geometry to satisfy moments and forces, often requiring extensive design efforts. Through a visual programming language, this paper introduces a new parametric method of designing hydrofoils wings with the aim of speeding up the process. Starting from the 2D airfoil geometry data the logic created makes it easier to edit parametrically the characteristics dimensions of the wings using user-friendly controls and coefficients as inputs of the design. This method in output produces both Brep surfaces and important preliminary information including estimating lift and drag. A case study is presented for the design of hydrofoil moth main wings.

Keywords: Design , Hydrofoil , Parametric

Background and Objective: The paper aims to demonstrate the integration of advanced technologies, including computed tomography (CT), computer-aided design (CAD), and additive manufacturing, for precise surgical planning and personalized solutions in the management of Osteogenesis Imperfecta (OI). The main research question is to determine how these technologies can be utilized to achieve successful surgical outcomes in severe cases of OI, such as the one presented in this study. Methods: The study involved an 11-year-old child with OI who suffered from a closed right diaphyseal femur fracture and severe lower extremity abnormalities. Virtual and physical planning procedures were carried out using CAD software based on patient-specific CT models. The length of the proximal and distal segments, cutting planes, and osteotomies were precisely defined to achieve the desired surgical corrections. Additionally, 3D models of the bones and bony segments were manufactured using additive manufacturing to physically recreate the surgical procedure. Results: The surgical treatment involved the correction of the right femur fracture and the left tibia and fibula in the first procedure, followed by the correction of the remaining segments in a second procedure. The Fassier-Duval telescopic intramedullary nail was used to stabilize the fracture and the osteotomy sites. The entire treatment course, from the first surgery to achieving partial weight-bearing, spanned approximately 15 weeks, including the two surgical procedures and staged rehabilitation. Post-surgery, the patient showed significant functional improvement, including the ability to stand and walk with assistance. Conclusion: The integration of advanced technologies in surgical planning for OI patients has shown promising results, leading to improved patient outcomes and reduced complications.

Keywords: Additive manufacturing , Computer aided design , Osteogenesis Imperfecta , Surgery planning

In radiotherapy treatments of mobile lesions, several strategies are used to treat the tumour while sparing the surrounding tissues [1]. The ADAM phantom (Anthropomorphic Dynamic breAthing Model) was developed to test dose delivery in lung cancer treatment. The aim of this study is to create ADAM A symbol representing the male gender, depicted as a circle with an arrow pointing diagonally upwards to the right. (Anthropomorphic Dynamic breAthing Model - Chemical structure diagram showing a hexagonal benzene ring with alternating double bonds. Attached to the ring is a hydroxyl group (OH) and a methyl group (CH3). The structure is labeled with standard chemical notation. male&female), a new modular phantom based on ADAM, to test free-breathing and deep inspiration breath hold (DIBH) breast radiotherapy treatments [2, 3]. The 3D model of ADAM was reconstructed using computed tomography (CT) scans to ensure a high level of anatomical accuracy. This digital model of ADAM served as the starting point for the design and development of ADAM Symbol representing a combination of male and female gender symbols, featuring a circle with an arrow pointing diagonally upward to the right and a cross extending downward. . 3D printable materials with tissue mimicking properties were selected to replicate tissues and organs [4, 5, 6, 7, 8–9]. The torso and chest were printed in PLA and the ribs and spine were printed in PLA StoneFil™ [10]. Tests have shown that ADAM A symbol representing the male gender, depicted as a circle with an arrow pointing diagonally upwards to the right. closely mimics human tissue in terms of Hounsfield Units. Its modular structure allows rapid transition between male and female configurations, making it suitable for realistic simulation of many clinical situations. ADAM A symbol combining the male and female gender symbols, featuring a circle with an arrow pointing diagonally upwards to the right and a cross extending downwards. demonstrates adequate performance for future testing gating and tracking devices in the treatment of moving breast and lung lesions. Chemical structure diagram showing a hexagonal benzene ring with alternating double bonds. Attached to the ring is a hydroxyl group (OH) and a methyl group (CH3). The structure is labeled with standard chemical notation.

Keywords: 3D Modelling , 3D Printing , Anthropomorphic Breathing Phantom , Tissue Mimicking

CAD tasks require engineering designers to manage cognitive, perceptual, and motor demands while solving complex design problems. Understanding the relationship between workload (WL) and CAD performance is essential for improving design outcomes and processes. However, this relationship, particularly under varying task complexities, remains insufficiently explored. This study investigates WL-performance relationships in two CAD modelling tasks of differing complexity. WL was measured with NASA TLX, including its individual components. CAD performance was evaluated and described through outcomes and processes using multiple metrics. The results revealed significant monotonic relationships between WL and performance, with stronger correlations in the high-complexity task.

Keywords: complexity , computer aided design (CAD) , human behaviour in design , performance , workload

This work presents a generative design algorithm for the semi-automatic reconstruction of sweepable surfaces from point clouds obtained through three-dimensional scanning. The proposed algorithm enables, starting from a 3D acquisition dataset, the correct automatic orientation of the mesh, the selection of a suitable cutting edge, and the specification of the number of transversal sections for an effective 3D model reconstruction. Additionally, it suggests a maximum number of points to be used for reconstructing the sectional curves. The mesh reconstruction is performed through a lofting operation, resulting in a non-uniform rational B-spline (NURBS) surface. The algorithm has been applied to a case study involving the front wing surface of a foil from the Olympic class iQFoil, which has recently garnered significant attention from researchers in the field of performance analysis. The obtained reconstructed surface exhibits very low deviation values when compared to the original mesh.

Keywords: 3D reconstruction , generative algorithm , innovative methods , iQFoil windsurfing foil

In recent years, Additive Manufacturing has experienced significant growth, yet its full potential is constrained by the lack of clear and easily replicable Design for Additive Manufacturing (DfAM) methodologies. Focusing on the product design stage, the current design approach for topology optimized parts involves an iterative re-design process to identify and reduce stress concentrations based on NURBS modelling, which is hardly replicable and heavily influenced by the designer's experience. This work aims to define two new workflows for DfAM that are easily replicable, highly automated, and based on numerical optimization tools. Leveraging the optimization tools available in 3DExperience integrated CAD platform, after topology optimization, the first workflow involves generating the skeletonization of the resulting geometry and reconstructing it with parametric surfaces, reducing maximum stresses via parametric optimization. The second workflow reconstructs the resulting optimized geometry as a non-parametric B-Rep surface, optimizing maximum stresses through automatic shape optimization.

Keywords: 3DExperience , Additive Manufacturing , Design for Additive Manufacturing , Design method , Design optimization , Parametric optimization , Shape optimization , Topology optimization

This study investigates Leonardo da Vinci's long-standing interest in milling technologies through the digital reconstruction of a pendulum-driven mill illustrated in the Codex Atlanticus. By tracing the chronological development of Leonardo's ideas across multiple sheets, this research highlights the continuity and evolution of his conceptual approach to energy transmission and mechanical automation. This work adopts a systematic design methodology to interpret and visualize the structural logic of the machine, integrating historical sources with engineering reasoning. The resulting CAD model reconstructs the key components (such as the gear train, escapement system, and pendulum) within a coherent architectural framework inspired by Leonardo's sketches. While the digital model remains a preliminary interpretation, it offers a historically grounded basis for future refinements. In particular, it lays the groundwork for potential physical reconstructions intended for museum display and public engagement. This study contributes to the broader understanding of Renaissance mechanical culture and the role of digital tools in heritage preservation and dissemination.

Keywords: ancient machines , CAD , engineering , heritage , history , Leonardo da Vinci , Mill , pendulum , technology , virtual model