Vickers indentation (IF) and single‐edge‐V‐notched beam (SEVNB), to measure the fracture toughness (KIC) of zirconia‐based dental ceramics and mathematical models were proposed to establish a ...correlation between both. Zirconia (ZrO2) stabilized with 3 mol. % of Y2O3 (3Y‐TZP) and 5 mol% of Y2O3 (5Y‐PSZ) were compacted (n = 42) and sintered for 2 h at different temperatures (1475°C, 1500°C, 1550°C, or 1600°C). After sintering, they were characterized by relative density using the ASTM C373‐88 standard, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The average grain size was measured according to the ASTM E1382‐97 standard. The fracture toughness (KIC) was determined using two methods: Vickers indentation fracture toughness (KIC‐IF): method based on mathematical modeling that considers the parameters used for the Vickers hardness test and Fracture toughness by the single‐edge‐V‐notch‐beam (KIC‐SEVNB): method proposed by ISO 23146:08. The main phases of the 3Y‐TZP and 5Y‐PSZ ceramics were ZrO2‐tetragonal and ZrO2‐cubic, respectively. The 3Y‐TZP specimens showed equiaxed grains with average grain sizes ranging from 0.55 to 0.79 μm. The grain sizes of 5Y‐PSZ of specimens sintered at 1475°C and 1600°C were 0.62 and 2.32 μm, respectively. For all ceramics the crack size ratio was c/a < 2.5, suggesting a Palmqvist‐type crack system. The fracture toughness measured by the Vickers indentation method (KIC‐IF) and by the SEVNB method (KIC‐SEVNB) was the same when the experimental data were fit to a mathematical model.
This study evaluated the effect of the surface roughness parameters on the flexural strength of Yttria-partially stabilized zirconia, Y-TZP ceramics: ZrO2 (3 mol%) or ZrO2 (5 mol%), as function of ...different surface finishing protocols: polishing or alumina (Al2O3) blasting. Zirconia discs were manufactured by CAD/CAM prototyping and sintered at different temperatures. The specimens were characterized by X-ray diffraction, scanning electron microscopy, biaxial flexural strength test and 3D profilometry. In all specimens tetragonal Y2O3-ZrO2 was observed to be the main crystalline phase. The 3D profilometry indicated that alumina blasting of ZrO2 (3 mol%) increased the roughness Ra around 16–26 times as opposed to the polished surfaces, and approximately 38 times for ZrO2 (5 mol%) specimens when compared to the polished samples. The results of flexural strength indicate that groups of ZrO2 (3 mol% Y2O3) ceramics present a reduction of 21–23% from polished to alumina blasted specimens. In the group of ZrO2 (5 mol% Y2O3) ceramics, a flexural strength reduction of 37.5% was observed. A correlation between flexural strength, failure size and different roughness parameters: Ra (arithmetic average of the absolute values of the profile heights over the evaluation length), Rz (measure of the ordinates of the five highest peaks and the five deepest valleys along the specimen's length) and PV (mean values of peak and valley measured in the specimen space) is proposed and indicates that Rz and PV should not be neglected in a systematic evaluation of the surface roughness effect on the bulk mechanical properties of dental ceramics.
The Electrocardiogram (ECG) is a low-cost exam commonly used to diagnose abnormalities in the cardiac cycle. Over the years, the scientific community has investigated the automatic classification of ...ECG signals driven by advanced Machine Learning (ML) techniques. Despite recent scientific advances, annotating large and diverse datasets to support the training of ML techniques is still very time-consuming and error-prone. Indeed, ML techniques whose training does not require extensive and well-annotated datasets are becoming even more prominent. Therefore, it is possible to correctly identify and classify abnormalities in the cardiac cycle (e.g., rare cardiologic disturbs) using limited data available in ECG datasets. However, the classification of heartbeats from digital tracings of ECG signals containing 12 leads from imbalanced datasets is challenging due to many existing heart diseases. This study investigates the few-shot learning paradigm based on Siamese Convolutional Neural Networks (SCNN), popular in imaging classification problems, to classify 12-Lead ECG heartbeats using a few training samples with supervised information. The proposed SCNN model presented an accuracy of up to 95% in a public dataset based on the hold-out validation method, implemented for different combinations of similarity and loss functions. Besides, using the 7-fold cross-validation method, the model presented a mean area under the curve of 89%. We also compared the class-by-class classification results with those of similar methods available in the literature, obtaining the same or better results based on performance metrics such as accuracy, precision, recall, and specificity.
Road safety impacts of the motorcycle in Brazil Vasconcellos, Eduardo Alcântara de
International journal of injury control and safety promotion,
06/2013, Letnik:
20, Številka:
2
Journal Article
Recenzirano
Brazil has had high indices of traffic injuries and deaths since the 1950s, mostly related to the increasing and irresponsible use of the automobile. Upon approval of the Brazilian Transit Code (CTB) ...in 1997, traffic injuries and deaths began to diminish, despite an increase in vehicle fleet size, a phenomenon that had never occurred previously. Concurrently, starting in 1991 and with a great intensity after 1996, there has been a sizeable increase in motorcycle production and use, facilitated and encouraged by public officials. Between 1995 and 2000 annual sales figures for motorcycles doubled and reached 2 million units in 2008. Traffic deaths associated with motorcycles increased exponentially, rising from 725 in 2006 to 10,143 in 2010, eliminating the advances gained by the CTB in reducing auto-related injuries. This article analyses the process and its impacts on road safety. The first part summarises the main public policy decisions related to the theme. Part two analyses changes in traffic safety after the introduction of this new technology. Part three looks at the possible political, economic and social motives that lie behind this process. The final part suggests solutions to the great prejudice caused to society and the nation.
Cooperation in research, development and innovation (RD&I) between universities or research institutes and industries plays a fundamental role in the economic development of a country. Industry ...benefits from state-of-the-art laboratories and technologies from academia, while institutes learn about business reality and market needs. Numerous barriers to the establishment and maintenance of these partnerships have been investigated and reported in the literature, but the information generated by these empirical studies is very fragmented and there is a need to consider the barriers systematically in order to clarify the topic. The aims of this systematic review were to analyze university-industry collaborations set up for the purpose of RD&I in an effort to recognize the barriers and facilitators of the process and to identify the approaches by which such barriers may be overcome. Following searches of the Scopus database and application of the exclusion criteria, 86 relevant articles were identified and submitted to bibliometric analysis. Subsequently, 75 articles were selected for in-depth content analysis, and the ideas embodied therein were presented in a structured and comprehensive manner. Barriers were evaluated according to three different theoretical perspectives, namely the triple helix and the entrepreneurial university, the relational social capital and value creation, and technology transfer and cultural differences. The facilitators were categorized as internal and external. The results obtained highlight the importance of fostering relational social capital and providing tax incentives to facilitate industry's pursuit of innovation through academia partnerships, and also show that collaborative barriers in RD&I may be overcome to some extent by starting with smaller projects and gradually increasing their complexity. Based on the findings outlined in this review, we propose various lines for future research.
Purpose
This study aims to investigate the risks associated with managing the dispersed knowledge in inter-organizational arrangements for innovation. Specifically, it proposes a model to analyze the ...knowledge management risks in open innovation, applied in four steps.
Design/methodology/approach
Initially, the authors carried out a systematic literature review (SLR) on the concepts that connect knowledge management, inter-organizational arrangements for innovation and risks. The SLR results led to a complementary theoretical review on the conceptual elements in question. Based on the findings, the authors have developed a model to analyze the knowledge management risks in open innovation, which was validated by experts. It was then studied the case of GOL Airlines, a company that uses innovation to overcome the paradox between low-cost and full service in the commercial air transportation industry, considering the application and adjustment of the proposed model.
Findings
Open innovation is one of the inter-organizational arrangement types most applied in the context of innovation. Relations between agents are the primary sources of risks when managing the dispersed knowledge in these arrangements. The authors have found five main risks associated, namely, risk of the innovative effort does not reach the expected objective, risk of knowledge transfer being ineffective, risk of misappropriation of value, risk of dependency (lock-in) and risk of relations.
Practical implications
The practical implication is the proposition of a procedure for applying the model to analyze the knowledge management risks in open innovation, which makes it a prescriptive model for identifying risks. The proposed model is described in four steps, namely, to identify the agents in the environment of the value of open innovation; to identify the types of relations of each agent; to consider the barriers to knowledge management in innovation; and to assess the risks considering the possibilities derived from the agents, their relationships and the barriers. The model is applied in the GOL case and the results are presented.
Originality/value
First, it uses a novel approach to investigate open innovation while studying its risks. This approach considers the knowledge is dispersed and flows from one organization to another through a combination of relations inside the environment of value where the open innovation materializes. Second, it contributes to theory development by opening a research front that fuses four areas: risk management, knowledge management, innovation and inter-organizational arrangements. Third, this paper proposes a theoretical model and presents its operationalization. The study aims to make an impact beyond academia and uses a case study to illustrate the model application in a real and interesting open innovation project to support the business model at GOL Airlines.
Summary
Simulations of cardiac electrophysiological models in tissue, particularly in 3D require the solutions of billions of differential equations even for just a couple of milliseconds, thus ...highly demanding in computational resources. In fact, even studies in small domains with very complex models may take several hours to reproduce seconds of electrical cardiac behavior. Today's Graphics Processor Units (GPUs) are becoming a way to accelerate such simulations, and give the added possibilities to run them locally without the need for supercomputers. Nevertheless, when using GPUs, bottlenecks related to global memory access caused by the spatial discretization of the large tissue domains being simulated, become a big challenge. For simulations in a single GPU, we propose a strategy to accelerate the computation of the diffusion term through a data‐structure and memory access pattern designed to maximize coalescent memory transactions and minimize branch divergence, achieving results approximately 1.4 times faster than a standard GPU method. We also combine this data structure with a designed communication strategy to take advantage in the case of simulations in multi‐GPU platforms. We demonstrate that, in the multi‐GPU approach performs, simulations in 3D tissue can be just 4× slower than real time.
Kinetic modeling of CuO chlorination with C2Cl4 Rogério Navarro, Correia de Siqueira; Vasconcellos, Eduardo Teixeira de
Journal of materials research and technology,
July-August 2019, Letnik:
8, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Chlorinating roasting is a well-known process devoted manly for the extraction of metals as volatile chlorides from oxidized minerals and residues. Experience has shown that the use of a gaseous ...chlorinating agent, Cl2, for example, and the incorporation of a reducing agent, charcoal, for example, stimulate, respectively the kinetics and thermodynamics of the desired reactions. In this scenario, organo-chlorinated molecules, such as, CCl4 and C2Cl4, appear as potential candidates for Cl2 replacement, as they can be easily volatilized and bear in the same molecule the chlorinating and reducing agents. In order to support reactor sizing, however, reliable kinetic data is needed, which are scarce regarding both mentioned chlorinating agents. In present work, chlorination of pure CuO samples with diluted C2Cl4 (P(C2Cl4)=0.0307atm) has been quantitatively appreciated in the range between 923 and 1173K. The kinetic data were modeled according to the Shrinking-Core model (SCM) and a quantitative agreement between experimental and calculated data has been found for all temperatures. Finally, a global activation energy of 117.9±10kJ/mol has been determined, which is close to earlier literature values for similar systems. A significant reduction of the form factor with temperature (3 to 1.5) has been detected, which, can be correlated to the partial sintering of the remaining CuO crystals.
Vasconcellos presents an analysis of the urban transport policies and creation of a discriminatory mobility system in Brazil, focusing on the existing urban mobility conditions and the possibilities ...for change towards a more equitable mobility system. It explores the vehicle congestion levels as an argument in support of proposals for road improvements. The paper takes a social and political approach and literature on mobility and social rights. It examines the main mobility consumption and their negative externalities on exclusion, pollution and safety. The urban mobility conditions involve the different roles of people while circulating in urban areas and the social and political characteristics of different social groups, their needs and interests.
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