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关键词： Performance evaluation   Solid modeling   Analytical models   Power amplifiers   Microwave circuits   Mathematical models   Microwave amplifiers   Numerical models   Integrated circuit modeling   Mixers  

摘要： Physics-based device simulators have undergone significant advancement over the last decades [1] , [2] , [3] , [4] . In the past, technology CAD (TCAD) simulation, i.e., the numerical analysis of electron devices through device structure discretization and the numerical solution of physical equations [5] , [6] , [7] , was generally assumed to be too demanding from a computational standpoint for the analysis of devices in the typical operating regime of microwave circuits, i.e., dynamic and nonlinear. Nowadays, leveraging advances in computation resources, and new numerical techniques based on iterative solutions of nonlinear models, all dynamic conditions can be efficiently addressed, including a large-signal (LS) periodic or quasi-periodic analysis [8] , [9] , [10] , [11] , [12] , [13] ( Figure 1 ). Typical applications include microwave circuits with multitone inputs, e.g., power amplifiers (PAs) or mixers.

关键词： Zirconia   CAD/CAM   Partial denture   Survival   Clinical  

摘要： Purpose: This retrospective clinical study aimed to evaluate the clinical outcomes of surveyed monolithic computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia crowns for abutment teeth in removable partial dentures (RPDs). Methods: Patients who received monolithic surveyed zirconia crowns were clinically examined. The crowns were examined according to the modified United States Public Health Service criteria, and Kaplan-Meier survival was determined. The effect of different variables on the survival and success rates was assessed using Cox regression analysis (alpha = 0.05). Results: A total of 297 crowns of 275 patients were evaluated over a mean period of 7 years. The cumulative survival and success rates were 95.6% and 91.2%, respectively. Complications were in the form of secondary caries (n=12 minor chipping (n=9 and debonding (n=5). A higher number of failures was observed in the mandibular molars P < 0.05). Conclusions: Surveyed monolithic zirconia crowns demonstrated high survival after 7 years of service. Monolithic zirconia is an excellent alternative to metal ceramic crowns for RPD abutments.

关键词： 3D printing   CAD   slicer   radical polymerization   photopolymerization   3D-Druck   Slicer   Radikalische Polymerisation   Photopolymerisation  

摘要： Als additives Fertigungsverfahren gewinnt der 3D-Druck in zahlreichen naturwissenschaftlichen und technischen Bereichen zunehmend an Bedeutung. Damit wird diese Technologie auch in der schulischen Berufsvorbereitung relevant. In diesem Artikel werden M & ouml;glichkeiten beleuchtet, wie diese innovative Technologie im Chemieunterricht integriert werden kann. Mit nur wenig Aufwand lassen sich hochwertige Unterrichtsmaterialien wie Modelle und ausgekl & uuml;gelte Lernspiele herstellen. Mit etwas mehr Engagement und CAD-Know-how werden ma ss geschneiderte L & ouml;sungen m & ouml;glich. Die Kosten f & uuml;r Lehrmaterial sind daher deutlich geringer als gew & ouml;hnlich. Zudem kann der 3D-Druck selbst ein Lerninhalt sein, bei dem Sch & uuml;ler Kunststoffe mit ihren typischen Eigenschaften als Werkstoffe kennen lernen und den Harzdrucker als Anwendung der radikalischen Polymerisation verstehen. Der Umgang mit digitalen Tools f & uuml;r den 3D-Druck f & ouml;rdert in motivierender Weise die digitalen Kompetenzen, welche zunehmend f & uuml;r Lehrer und Sch & uuml;ler relevant werden.

关键词： Transient ischaemic dilatation   Non-obstructive coronary artery disease   N-13-ammonia PET   Myocardial perfusion imaging   Prognosis  

摘要： Objective Transient ischaemic dilatation (TID) had incremental diagnostic and prognostic value in obstructive coronary artery disease (CAD but its clinical significance in patients with non-obstructive CAD remains unknown. We aimed to explore the prognostic value of TID in patients with non-obstructive CAD by 13N-ammonia PET imaging. Methods We retrospectively studied 131 consecutive patients with non-obstructive CAD undergoing one-day rest-stress 13N-ammonia PET myocardial perfusion imaging (MPI). TID was automatically generated using CardIQ Physio software. The receiver operative characteristic (ROC) curve was used to determine the optimal threshold of TID. The follow-up outcome was major adverse cardiac events (MACE a composite of re-hospitalization for heart failure or unstable angina, late revascularization, non-fatal myocardial infarction, and cardiac death. Cardiac event-free survivals for normal and abnormal TID were compared using Kaplan-Meier plots and log-rank tests. Results During a median follow-up of 42.08 +/- 17.67 months, 22 (16.7%) patients occurred MACE. The optimal cut-off value of TID was 1.03 based on MACE. Our preliminary outcome analysis suggests that TID-abnormal subjects had a lower overall survival probability. Furthermore, our multivariate analysis reveals abnormal TID was the only independent predictor for MACE in non-obstructive CAD. In the subgroup analysis, an abnormal TID was an independent predictor for MACE in patients with abnormal perfusion patterns. Conclusion Among patients with non-obstructive CAD, PET-derived TID >= 1.03 may identify those with a high risk of subsequent MACE independently. It was also an independent risk factor for poor prognosis in patients with abnormal perfusion.

关键词： Biofilm formation   CAD/CAM dental materials   In situ   Real-time PCR   Scanning electron microscopy  

摘要： The aim of this research was to determine if there are differences in early bacterial adhesion among CAD/CAM dental materials after 24 h exposure in the oral environment. One hundred twenty specimens were prepared according to the manufacturer's recommendations and divided into six groups: RBC (resin-based composite PMMA (polymethyl methacrylate PEEK (polyether ether ketone ZP (zirconia polished ZG (zirconia glazed and cobalt-chromium alloy (CoCr alloy). Twenty healthy participants were instructed to carry an intraoral device with six specimens, one per group, for 24 h. Thereafter, real-time polymerase chain reaction (qPCR) and scanning electron microscopy (SEM) analyses enabled quantification and 2D view of biofilm formed on the specimens' surfaces. Kruskal-Wallis test and Dunn's post hoc analysis were used for inter-group comparison and data were presented as median (minimum-maximum). RBC specimens accumulated less bacteria, in comparison with ZG (p = 0.017) and PEEK specimens (p = 0.030 that dominated with the highest amount of adhered bacterial biofilm. PMMA, CoCr, and ZP specimens adhered more bacteria than RBC (p > 0.05 and less than ZG (p > 0.05) and PEEK (p > 0.05). The bacterial number varied considerably among participants. The obtained results enable a closer view into the susceptibility of CAD/CAM materials to microorganisms during the presence in the oral environment, which can be beneficial for a proper selection of these materials for a variety of dental restorations.

关键词： additive manufacturing   brushing   coffee thermal cycling   roughness   stainability   translucency  

摘要： Purpose: To evaluate the surface roughness, optical properties, and microhardness of additively or subtractively manufactured CAD-CAM materials after simulated brushing and coffee thermal cycling.Material and methods: Two additively manufactured resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and 3 subtractively manufactured materials (a reinforced composite (Brilliant Crios, BC a polymer-infiltrated ceramic network (Enamic, VE and a feldspathic ceramic (Mark II, VM were used to fabricate disk-shaped specimens (& Oslash;10x1-mm n = 10). Surface roughness, Vickers microhardness, and color coordinates were measured after polishing, while surface roughness was also measured before polishing. Specimens were then subjected to 25000 cycles of brushing and 10000 cycles of coffee thermal cycling, and measurements were repeated after each time interval. Color difference (Delta E-00) and relative translucency parameter (RTP) were calculated. Robust analysis of variance test was used to evaluate surface roughness, Delta E-00, and RTP data, while generalized linear model analysis was used for microhardness data (alpha = 0.05).Results: Material type and time interval interaction affected tested parameters (p <= 0.002). In addition, material type affected all parameters (p < 0.001) other than surface roughness (p = 0.051 and time interval affected surface roughness and microhardness values (p < 0.001). Tested materials mostly had their highest surface roughness before polishing (p <= 0.026);however, there was no clear trend regarding the roughness of materials within different time intervals along with Delta E00 and RTP values within materials or time intervals. VS and CT had the lowest microhardness regardless of the time interval, while the remaining materials were listed as VM, VE, and BC in decreasing order (p < 0.001). Coffee thermal cycling only reduced the microhardness of VM (p < 0.001).Conclusions: Tested additively manufactured resins can be considered more suscept

关键词： fixture   design   porous block   CNC machining   FEM  

摘要： This paper presents a new innovative approach for designing and manufacturing a fixture for locating and clamping porous blocks of biocompatible material, which is required for their machining on CNC machines. Manufacturing porous blocks for their application in medical and/or dental fields is gaining traction. However, limited solutions are available today. In order to address this issue, a new design has been proposed for locating and clamping porous blocks. Finite element analysis was used as a verification tool for the designed fixture with the workpiece, which showed a low concentration of stresses. After the manufacturing, dimensional verification in the form of CAD analysis showed small deviations on the manufactured object with deviations peaking around +0.015 mm, thus validating the adequate locating and clamping of the workpiece.

关键词： Image segmentation  

摘要： Explanation methods are being used to understand model reasoning and decision-making. In this work, we introduce a novel point of view for these methods. We first apply Grad-CAM, initially proposed to explain image classification models, to a segmentation network. Then, we show that small negative gradients can be used to enhance model predictions in the case of under-pixel prediction without retraining. Instead of discarding negative gradients with ReLU as Grad-CAM does, we propose Drift-Grad-CAM with two heuristics methods of thresholding as a novel approach that leverages the informative potential hidden within negative gradients. Drift-Grad-CAM method applied to U-Net and DeepLabV3 model with a ResNet-50 backbone and on two datasets, results in an improvement of performance metrics, Dice and IoU scores, by up to 46% without retraining the model. It demonstrates that some small negative gradients are underestimated but valuable source of information for pixel prediction, and they should be considered as meaningful as positive gradients in future works.

关键词： additive manufacturing (AM)   design for additive manufacturing (DfAM)   lattice structures   CAD   road bike saddle  

摘要： Design for additive manufacturing (DfAM) has made significant advancements in recent years, with development focusing on pivotal aspects such as topology optimization (TO generative design (GD lattice structures, and AI-based algorithms. This paper puts forth a proposed methodology for the development of customizable bike saddle pads for manufacturing with AM. The approach entails the selection of appropriate AM processes and materials, the evaluation of material properties through compression testing, an initial saddle pressure mapping and bike fitting, the design and AM of bespoke saddle pads based on the initial measurements, and a validation pressure mapping and bike fitting. The investigation yielded clear findings regarding improvements in both pressure distribution and the change in pressure peaks, as well as an improvement in riding comfort. The findings indicate that although the overall process is innovative, improvements are required to streamline the measuring, modeling, and manufacturing workflow.

关键词： Editable CAD models   Parametric modeling   CAD model reconstruction   Deep neural networks  

摘要： This paper introduces a novel framework capable of reconstructing editable parametric CAD models from dumb B-Rep models. First, each B-Rep model is represented with a network-friendly formalism based on UV- graph, which is then used as input of eCAD-Net, the new deep neural network-based algorithm that predicts feature-based CAD modeling sequences from the graph. Then, the sequences are scaled and fine-tuned using a feature matching algorithm that retrieves the exact parameter values from the input dumb CAD model. The output sequences are then converted in a series of CAD modeling operations to create an editable parametric CAD model in any CAD modeler. A cleaned dataset is used to learn and validate the proposed approach, and is provided with the article. The experimental results show that our approach outperforms existing methods on such reconstruction tasks, and it outputs editable parametric CAD models compatible with existing CAD modelers and ready for use in downstream engineering applications.