课程文献中心 更多>>

关键词： biomaterials   CAD/CAM   dental biomaterials   cytotoxicity   biocompatibility   biofilm   oral cavity   water contact angle  

摘要： The aim of this study is to present the characteristics and a comparison of four different commercial materials dedicated to the CAD/CAM technique in dentistry, all of which can be classified as ceramic materials. Its purpose is also to evaluate the impact of surface treatment on the cytotoxicity and microbiological properties of the materials. The CAD/CAM technique has a perpetually growing role in modern reconstructive dentistry. It requires a material's possession of peculiar characteristics, such as mechanical resistance, durability, functionality (similar to natural tissues), good aesthetics and biocompatibility. To critically evaluate a biomaterial, both manufacturer claims and in vitro tests should be considered. Further steps of evaluation may include animal tests and clinical trials. There are certain attributes of biomaterials that may be modified by surface treatment that can be crucial to the clinical success of the material. The evaluated materials were Vita Suprinity (VITA-Zahnfabrik, Germany), Vita Mark II (VITA-Zahnfabrik, Germany), Celtra Duo (Dentsply Sirona, USA) and Empress Cad (Ivoclar Vivadent, Liechtenstein). They are available in the form of prefabricated blocks of various diameters and are popular among operators performing clinical procedures using CAD/CAM. Standardized blocks of each material were prepared. Half of them had their surface polished. Further, half of all the samples were covered by a nano-copper layer. The samples were evaluated for cytotoxicity, presented on a 0-4 scale, adhesion susceptibility and potential of forming a biofilm on their surface. Physicochemical properties such as the water contact angle (WCA) were evaluated for the tested materials. The influence of copper coating on cytotoxicity cannot be unequivocally stated or denied. Surface polishing did not affect the materials' cytotoxicity, but it increased the WCA of all materials and, therefore, their hydrophobicity. Different degrees of adhesion ability and biofi

关键词： CADCAM   History   Commercialization   Software packages  

摘要： Patrick J. Hanratty was an early developer of CAD/CAM software applications. In addition to helping develop early numerical control programming software systems in the 1950s and 1960s, he and the companies he later founded developed some of the first integrated CAD/CAM software systems: INTERAPT at Integrated Computer Systems and then the machine-independent ADAM at Manufacturing and Consulting Services (MCS). ADAM-the first commercially available, interactive design, drafting, and manufacturing system-and subsequent MCS product releases were sold and licensed in a variety of industries, including shipbuilding, manufacturing, aerospace, and nuclear systems.

关键词： biomechanical phenomena   orthodontics   retainer   orthodontic retainer adverse effects   force   torque  

摘要： (1) Background: After more than a decade since their first description, Inadvertent Tooth Movements (ITMs) remain an adverse effect of orthodontic retainers without a clear etiology. To further investigate the link between ITMs and the mechanical properties of different retainers, the response upon vertical loading was compared in three retainer types (two stainless steel and one nickel-titanium). The influence of different reference teeth was also considered. (2) Methods: Three retainers (R1, R2, R3) were tested in a newly developed biomechanical analysis system (FRANS). They were bonded to 3D-printed models of the lower anterior jaw and vertically displaced up to 0.3 mm. Developing forces and moments were recorded at the center of force. (3) Results: The vertical displacement caused vertical forces (Fz) and labiolingual moments (My) to arise. These were highest in the lateral incisors (up to 2.35 +/- 0.59 N and 9.27 +/- 5.86 Nmm for R1;1.69 +/- 1.06 N and 7.42 +/- 2.65 Nmm for R2;3.28 +/- 1.73 N and 15.91 +/- 9.71 Nmm for R3) for all analyzed retainers and with the R3 retainer for all analyzed reference teeth, while the lowest Fz and My values were recorded with the R1 retainer. (4) Conclusions: Displacements of 0.2 mm and larger provided forces and moments which could be sufficient to cause unwanted torque movements, such as ITMs, in all analyzed retainers. Clinicians must be mindful of these risks and perform post-treatment checkups on patients with retainers of all materials.

关键词： Software engineering   Companies   Vibrations   Finite element analysis   Computational modeling   Steel   Industries   Mechanical engineering   Design automation   CADCAM   History  

摘要： The Structural Dynamics Research Corporation (SDRC) was a mechanical computeraided engineering (MCAE) company with a focus on technical innovation and training. Originally founded as a consulting firm in 1967, SDRC grew into a half-billion-dollar software company with product and process software solutions in the computer-aided design, product data management, and MCAE markets, including the Integrated Design Engineering Analysis System (I-DEAS) integrated MCAE system and the Teamcenter process system. This article looks at SDRC's history, from its founding until the acquisition of SDRC by Electronic Data Systems in 2001. Topics includes the company's vision and leadership;its technology and software;major sales, partnerships, and joint ventures with customers, including General Electric, Boeing, Ford, and Nissan;and an overview of its financial results and profitability.

关键词： Solid modeling   Task analysis   Complexity theory   Transformers   Point cloud compression   Computational modeling   Informatics   CAD sketch   industrial product design   pointer module   set prediction   sketch analysis  

摘要： The design and analysis of computer-aided design (CAD) sketches play a crucial role in industrial product design, primarily involving CAD primitives and their interprimitive constraints. To address challenges related to error accumulation in autoregressive models and the complexities associated with self-supervised model design for this task, we propose a two-stage network framework. This framework consists of a primitive network and a constraint network, transforming the sketch analysis task into a set prediction problem to enhance the effective handling of primitives and constraints. By decoupling target types from parameters, the model gains increased flexibility and optimization while reducing complexity. In addition, the constraint network incorporates a pointer module to explicitly indicate the relationship between constraint parameters and primitive indices, enhancing interpretability and performance. Qualitative and quantitative analyzes on two publicly available datasets demonstrate the superiority of this method.

关键词： course enrolment intention   formality   senior instructor   student perception   title  

摘要： In this research, we explore the effect of college instructors' use of formal versus casual titles on student perceptions as a function of the instructors' academic ranks. We conducted two studies: the first surveying students to study their expectations and preferences of formality and rank, and the second using experimental manipulations of title formality and instructor rank to examine the effects on student perceptions of instructors and their classes. Our data indicate that a full professor is perceived more favourably than a graduate assistant when using a casual title (their first name). Conversely, the pattern goes the opposite when they use a formal title. These insights were assessed through course favourability and enrolment intention and were rooted in two fundamental individual traits: competence and approachableness. In addition, the effects are less pronounced for students with previous exposure to the course content, suggesting course experience as a moderator. This study offers guidance on student-instructor interactions and provides insights for educators in presenting themselves through different titles.

关键词： Geometrical complexity   Product complexity   Methodological framework   CAD   Survey  

摘要： Modern industries are experiencing radical changes due to the introduction of high technological innovations. In this context, even more highly complex and customized products are required, increasing the need of tending towards the concept of complexity for free. In addition, new products are conceived with the circular economy in mind, considering possible multi life-cycle at the early design stage to reduce time and costs while ensuring high quality standards. To evaluate the overall product complexity, this research combines geometrical, manufacturing, assembly, and disassembly complexity features, typically treated separately in the literature. The research is divided into two parts and proposes a novel methodological framework for assessing product complexity with an overall view, integrating many aspects of product life cycle. The framework aims to create a rank of product configurations, on the base of complexity. Making complexity assessment procedures objective is essential to effectively support decision-making processes, especially when introducing advanced manufacturing technologies such as Additive Manufacturing (AM). Additionally, it is necessary to know the complexity of the individual components before the overall assembly. This paper deals with the first part of the research, proposing the aforementioned novel methodological framework, with a great focus on geometrical complexity. A geometrical complexity index is defined through experimental and numerical surveys, involving CAD modeling experts and considering numerous metrics found in the technical literature. The proposed methodological framework and the geometrical complexity metric can provide useful tools for businesses looking to evaluate their product complexity and identify areas for improvement.