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关键词： Quadrilateral and Hexahedral Mesh generation   Block decomposition   Reinforcement learning  

摘要： The problem of hexahedral mesh generation of general CAD models has vexed researchers for over 3 decades and analysts often spend more than 50% of the design-analysis cycle time decomposing complex models into simpler blocks meshable by existing techniques. The decomposed blocks are required for generating good quality meshes (tilings of quadrilaterals or hexahedra) suitable for numerical simulations of physical systems governed by conservation laws. We present a novel AI-assisted method for decomposing (segmenting) planar CAD (computer-aided design) models into well shaped rectangular blocks. Even though the simple examples presented here can also be meshed using many conventional methods, we believe this work is proof-of-principle of a AI-based decomposition method that can eventually be generalized to complex 2D and 3D CAD models. Our method uses reinforcement learning to train an agent to perform a series of optimal cuts on the CAD model that result in a good quality block decomposition. We show that the agent quickly learns an effective strategy for picking the location and direction of the cuts and maximizing its rewards. This paper is the first successful demonstration of an agent autonomously learning how to perform this block decomposition task effectively, thereby holding the promise of a viable method to automate this challenging process for more complex cases.

关键词： CAD/CAM   de-bonding   hybrid abutment   implant prosthesis   implant-supported crown   systematic review   titanium-based abutment  

摘要： Objectives: The objective of this study is to investigate the outcomes of clinically relevant laboratory studies regarding the cementation of implant-supported restorations over ti-bases. Materials and Methods: The present study has been conducted according to PRISMA statement. An electronic search was performed, including publications up to March 2024, to identify studies investigating the parameters affecting the cementation between ti-bases and CAD/CAM prostheses. An assessment of the internal validity was performed, using a custom-made risk of bias tool (QUIN). Results: From the included studies, 40.1% were reported on luting systems, 25% on ti-base surface treatment, 25% on restoration surface, 21.8% on restoration material, and 18.7% on ti-base height. The majority of the included studies were associated with a medium risk of bias. In the absence of micro-retentive features, air-abrasion of ti-bases with a minimum height of 3.5 mm can be beneficial for restoration's retention. The bonding performance can vary not only between different bonding systems but also for different applications within the same system, based on a restoration's material and surface treatment as well as on ti-base height and surface treatment. Conclusions: The height of the ti-base seems to be the prevailing factor as it constitutes the prerequisite for other modifications of the bonding surfaces to have an advantageous effect. Since the parameters that can affect bonding performance between ti-base and restoration can interact with each other, it is important for the clinician to focus on verified bonding protocols.

关键词： Orthosis modelling   Reverse engineering   CAD   Additive manufacturing   Topology optimization   Thermal comfort  

摘要： An area of interest in orthopaedics is the development of efficient customized neck orthoses, considered that pathologies which affect the neck area are widespread. Advanced acquisition and modelling approaches combined with Additive Manufacturing (AM) can potentially provide customized orthoses with improved performance and complexity. However, in the design of these devices, besides functional and structural requirements, benefit and comfort of the patient should be a main concern, in particular, at the early stage of design during the acquisition of the body's part, and while using the printed orthosis. In this paper, a scanning system with three sensors was developed which allows a fast, about 5 s, and accurate acquisition of the neck area with minimum discomfort for the patient. A neck orthosis with a ventilation pattern obtained by Topology Optimization (TO), lightened by about 35%, was also established. In fact, a main role for comfort is played by the ventilation pattern which contributes both to lightness and breathability. Its structural and comfort performance was evaluated in comparison with an orthosis with a ventilation pattern configured by Voronoi cells. Structural assessment was carried out by means of finite element analysis under main loading conditions. An evaluation of neck temperatures in relation to wearing 3D printed prototypes, manufactured with Hemp Bio-Plastic & REG;filament, was finally conducted by means of a thermal imaging camera. TO orthosis prototype showed a better performance regarding thermal comfort, with a maximum increase of neck temperature less than 1 & DEG;C, which makes the proposed configuration very promising for user's comfort.

关键词： Military aircraft   Airplanes   Aerodynamics   Manufacturing   Three-dimensional displays   Smoothing methods   Companies   Design automation   CADCAM   Market research   Commercialization  

摘要： This article describes, from the author's viewpoint, the history of CAD/CAM software technologies starting in the French aviation industry, which became a platform used to design and manufacture products in almost every industry. It begins with work during the 1970s on computer-aided design (CAD) at Dassault Aviation that led to the development of CATIA software. It continues with the founding and managing of the French company Dassault Systemes in the 1980s which, in partnership with IBM, became a leader in computer-aided design and manufacturing (CAD/CAM) in the 1990s, delivering its design and manufacturing software tools to a wide variety of industries worldwide.

关键词： L1CAM   LC3   LIR   A beta   autophagy   Alzheimer's disease  

摘要： Abnormal protein accumulations in the brain are linked to aging and the pathogenesis of dementia of various types, including Alzheimer's disease. These accumulations can be reduced by cell indigenous mechanisms. Among these is autophagy, whereby proteins are transferred to lysosomes for degradation. Autophagic dysfunction hampers the elimination of pathogenic protein aggregations that contribute to cell death. We had observed that the adhesion molecule L1 interacts with microtubule-associated protein 1 light-chain 3 (LC3), which is needed for autophagy substrate selection. L1 increases cell survival in an LC3-dependent manner via its extracellular LC3 interacting region (LIR). L1 also interacts with A beta and reduces the A beta plaque load in an AD model mouse. Based on these results, we investigated whether L1 could contribute to autophagy of aggregated A beta and its clearance. We here show that L1 interacts with autophagy-related protein 12 (ATG12) via its LIR domain, whereas interaction with ubiquitin-binding protein p62/SQSTM1 does not depend on LIR. A beta, bound to L1, is carried to the autophagosome leading to A beta elimination. Showing that the mitophagy-related L1-70 fragment is ubiquitinated, we expect that the p62/SQSTM1 pathway also contributes to A beta elimination. We propose that enhancing L1 functions may contribute to therapy in humans.

关键词： Contact dynamics   clearance joint   multibody mechanical system   conjugate cam linkage mechanism   optimization  

摘要： The dynamic behavior of the mechanism is subject to the influence of the clearance in the joints. Existing methods for improving the mechanism's performance usually focus on one type of clearance joint, ignoring the interaction among multiple different types of clearance joints. To address this gap, an optimization method is proposed to lower adverse impact forces and vibrations in planar conjugate cam linkage mechanisms with cam and revolute clearance joints. The contact force model of the clearance joint is formulated using the Flores contact force model and the modified Coulomb friction model. Based on these models and Lagrange's equation of the first kind, the dynamic equations of the mechanism describe its behavior during operation. The optimization method is aimed at minimizing the peak of the mechanism's maximum absolute acceleration by employing the whale optimization algorithm (WOA) to optimize the length of the linkages and the initial angles between them. Additionally, the slider stroke serves as a constraint function. Finally, the effectiveness of the approach is validated using an example of a planar conjugate cam linkage mechanism. Simulation results show a reduction of 65.8% in acceleration peaks and 64.2% in the clearance revolute joint maximum contact force.

关键词： CAD   mathematical apparatus   parallel computing   point calculus   coordinate-by-coordinate calculation   coordinate vector   invariants of parallel projection   and hidden parallelism  

摘要： The purpose of this work is to develop a mathematical apparatus and computational algorithms for implementation of parallel computing in geometric modeling and computer-aided design (CAD) systems. The analysis of existing approaches to parallel computing implementation in CAD systems is carried out. As a result, it is found that most information modeling and CAD systems do not support parallel computing at the level of the geometric kernel. A concept for the development of a CAD geometric kernel based on the invariants of parallel projection of geometric objects onto the axes of the global coordinate system is proposed. It combines the potential of constructive methods for geometric modeling, capable of parallelizing geometric constructions by tasks (message passing), and the mathematical apparatus of point calculus, capable of parallelization by data through coordinate-by-coordinate calculation (data parallel). The use of the coordinate-by-coordinate calculation for point equations not only makes it possible to parallelize computations along coordinate axes, but also ensures the consistency of computational operations with respect to threads, which significantly reduces the idle time and optimizes the CPU operation to achieve the maximum effect from the use of parallel computing.

关键词： non-alcoholic fatty liver disease   NALFD   endothelial dysfunction   coronary artery disease   CAD   prevention   treatment   genetics  

摘要： Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is regarded as a liver manifestation of metabolic syndrome. It is linked to insulin resistance, obesity, and diabetes mellitus, all of which increase the risk of cardiovascular complications. Endothelial dysfunction (EnD) constitutes the main driver in the progression of atherosclerosis and coronary artery disease (CAD). Several pathophysiological alterations and molecular mechanisms are involved in the development of EnD in patients with NAFLD. Our aim is to examine the association of NAFLD and CAD with the parallel assessment of EnD, discussing the pathophysiological mechanisms and the genetic background that underpin this relationship. This review delves into the management of the condition, exploring potential clinical implications and available medical treatment options to facilitate the deployment of optimal treatment strategies for these patients.

关键词： Companies   Three-dimensional displays   Engineering drawings   Aerospace industry   Aerospace engineering   Solid modeling   Aerodynamics   Computer numerical control   Numerical models   Automotive engineering   History   Design automation   CADCAM  

摘要： Between the late 1950s and mid-1980s, some major automotive and aerospace companies developed their own CAD/CAM programs. They wanted to leverage the programs to replace manual drafting and design practices to improve productivity, produce better designs, and accrue both technical and economic advantages. Frequently, these internal systems featured proprietary 3-D surface modeling, numerical control program generation, and engineering analysis capabilities. While shipbuilding, architecture, petrochemical, and electronics companies also moved from manual to CAD/CAM methods, they typically trailed the automotive and aerospace companies.

关键词： CAD-CAM   digital technology   denture space   mandibulectomy   maxillofacial prosthesis  

摘要： This clinical report summarizes a workflow that introduces two approaches for fabricating a metal framework removable partial denture for a marginal mandibulectomy patient. First, the pre-existing denture was adjusted according to the piezographic technique to determine the optimal configuration for adhering to the available denture space. Second, nology was used to fabricate a new removable partial denture by digitally scanning the oral condition and the well-adjusted denture and then using the obtained data to design and fabricate the new denture. These two approaches can help to reduce chair time not only for maxillofacial prosthetic treatment but also for other denture cases.