Recent Developments of Fracture Mechanics Tools for Nozzle Corners

2017 ◽  
Author(s):  
Arnaud Blouin ◽  
Stéphane Chapuliot ◽  
Stéphane Marie ◽  
André Jaubert ◽  
Stephan Courtin
Keyword(s):  
Fracture Mechanics ◽  
Shock Loading ◽  
Recent Effort ◽  
Analytical Scheme ◽  
Evaluation Scheme ◽  
Important Target ◽  
Recent Developments ◽  
Growth Evaluation ◽  
Large Benefit ◽  
High Level

A recent effort was performed within AREVA-NP in order to develop and validate specific tools dedicated to the Fracture Mechanics Assessment of nozzle and penetration corners. This work is motivated by the need to perform accurate defect assessments for this geometry potentially submitted to a high level of stress. It includes: • The development of a specific compendium for the calculation of the Stress Intensity Factor under various types of loading like internal pressure or cold thermal shocks; • The evaluation of the effect of plasticity through simplified analytical schemes; • The validation through the comparison to existing solutions. One important target of those tools being the Fatigue Crack Growth evaluation under cyclic thermal shock loading situations, a validation of the fully analytical evaluation scheme was performed by a comparison to a complex 3D Finite Element Modelling of a defect propagating at a flange corner. This comparison is presented in the paper and illustrates the large benefit in terms of time and simplicity of the analytical scheme for such evaluation.

What Can Digitization Do For Formulated Product Innovation and Development

2020 ◽  
Author(s):  
James McDonagh ◽  
William Swope ◽  
Richard L. Anderson ◽  
Michael Johnston ◽  
David J. Bray
Keyword(s):  
High Performance ◽  
Quality Data ◽  
High Quality Data ◽  
Base Level ◽  
Hybrid Approaches ◽  
Digital Ecosystem ◽  
Recent Developments ◽  
Chemical Simulation ◽  
High Level ◽  
Physical And Chemical

Digitization offers significant opportunities for the formulated product industry to transform the way it works and develop new methods of business. R&D is one area of operation that is challenging to take advantage of these technologies due to its high level of domain specialisation and creativity but the benefits could be significant. Recent developments of base level technologies such as artificial intelligence (AI)/machine learning (ML), robotics and high performance computing (HPC), to name a few, present disruptive and transformative technologies which could offer new insights, discovery methods and enhanced chemical control when combined in a digital ecosystem of connectivity, distributive services and decentralisation. At the fundamental level, research in these technologies has shown that new physical and chemical insights can be gained, which in turn can augment experimental R&D approaches through physics-based chemical simulation, data driven models and hybrid approaches. In all of these cases, high quality data is required to build and validate models in addition to the skills and expertise to exploit such methods. In this article we give an overview of some of the digital technology demonstrators we have developed for formulated product R&D. We discuss the challenges in building and deploying these demonstrators.<br>

Radiotherapy for Brain Tumors: Current Practice and Future Directions

2020 ◽  
Vol 16 (3) ◽  
pp. 182-195
Author(s):  
Sarah Baker ◽  
Natalie Logie ◽  
Kim Paulson ◽  
Adele Duimering ◽  
Albert Murtha
Keyword(s):  
Brain Tumors ◽  
Treatment Strategies ◽  
Brain Parenchyma ◽  
Benign Tumors ◽  
Tumor Control ◽  
Normal Brain ◽  
Neurocognitive Deficits ◽  
Close Proximity ◽  
Recent Developments ◽  
High Level

Radiotherapy is an important component of the treatment for primary and metastatic brain tumors. Due to the close proximity of critical structures and normal brain parenchyma, Central Nervous System (CNS) radiotherapy is associated with adverse effects such as neurocognitive deficits, which must be weighed against the benefit of improved tumor control. Advanced radiotherapy technology may help to mitigate toxicity risks, although there is a paucity of high-level evidence to support its use. Recent advances have been made in the treatment for gliomas, meningiomas, benign tumors, and metastases, although outcomes remain poor for many high grade tumors. This review highlights recent developments in CNS radiotherapy, discusses common treatment toxicities, critically reviews advanced radiotherapy technologies, and highlights promising treatment strategies to improve clinical outcomes in the future.

scholarly journals CoKnowEMe: An Edge Evaluation Scheme for QoS of IoMT Microservices in 6G Scenario

2021 ◽  
Vol 13 (7) ◽  
pp. 177
Author(s):  
Grazia Veronica Aiosa ◽  
Barbara Attanasio ◽  
Aurelio La Corte ◽  
Marialisa Scatá
Keyword(s):  
Communication Networks ◽  
Systems Approach ◽  
Evaluation Model ◽  
Service Evaluation ◽  
Important Change ◽  
Supplementary Information ◽  
Analytical Scheme ◽  
Evaluation Scheme ◽  
Reducing Costs ◽  
And Performance

The forthcoming 6G will attempt to rewrite the communication networks’ perspective focusing on a shift in paradigm in the way technologies and services are conceived, integrated and used. In this viewpoint, the Internet of Medical Things (IoMT) represents a merger of medical devices and health applications that are connected through networks, introducing an important change in managing the disease, treatments and diagnosis, reducing costs and faults. In 6G, the edge intelligence moves the innovative abilities from the central cloud to the edge and jointly with the complex systems approach will enable the development of a new category of lightweight applications as microservices. It requires edge intelligence also for the service evaluation in order to introduce the same degree of adaptability. We propose a new evaluation model, called CoKnowEMe (context knowledge evaluation model), by introducing an architectural and analytical scheme, modeled following a complex and dynamical approach, consisting of three inter-operable level and different networked attributes, to quantify the quality of IoMT microservices depending on a changeable context of use. We conduct simulations to display and quantify the structural complex properties and performance statistical estimators. We select and classify suitable attributes through a further detailed procedure in a supplementary information document.

scholarly journals Knowledge-driven perceptual organization reshapes information sampling via eye movements

2021 ◽  
Author(s):  
Marek A. Pedziwiatr ◽  
Elisabeth von dem Hagen ◽  
Christoph Teufel
Keyword(s):  
Eye Movements ◽  
Feature Space ◽  
Object Perception ◽  
Visual Features ◽  
Object Representations ◽  
Object Knowledge ◽  
Recent Developments ◽  
Gaze Behaviour ◽  
Information Sampling ◽  
High Level

Humans constantly move their eyes to explore the environment and obtain information. Competing theories of gaze guidance consider the factors driving eye movements within a dichotomy between low-level visual features and high-level object representations. However, recent developments in object perception indicate a complex and intricate relationship between features and objects. Specifically, image-independent object-knowledge can generate objecthood by dynamically reconfiguring how feature space is carved up by the visual system. Here, we adopt this emerging perspective of object perception, moving away from the simplifying dichotomy between features and objects in explanations of gaze guidance. We recorded eye movements in response to stimuli that appear as meaningless patches on initial viewing but are experienced as coherent objects once relevant object-knowledge has been acquired. We demonstrate that gaze guidance differs substantially depending on whether observers experienced the same stimuli as meaningless patches or organised them into object representations. In particular, fixations on identical images became object-centred, less dispersed, and more consistent across observers once exposed to relevant prior object-knowledge. Observers' gaze behaviour also indicated a shift from exploratory information-sampling to a strategy of extracting information mainly from selected, object-related image areas. These effects were evident from the first fixations on the image. Importantly, however, eye-movements were not fully determined by object representations but were best explained by a simple model that integrates image-computable features and high-level, knowledge-dependent object representations. Overall, the results show how information sampling via eye-movements in humans is guided by a dynamic interaction between image-computable features and knowledge-driven perceptual organisation.

scholarly journals A DAMAGE PROGNOSIS METHODOLOGY FOR A SIMPLE CRACKED BEAM

2018 ◽  
Vol 48 (1) ◽  
pp. 43-49
Author(s):  
E. A. PRESEZNIAK ◽  
J. E. PEREZ IPIÑA ◽  
C. A. BAVASTRI
Keyword(s):  
Fracture Mechanics ◽  
Nonlinear Optimization ◽  
Optimization Techniques ◽  
Crack Identification ◽  
Remaining Life ◽  
Damage Prognosis ◽  
Mechanics Concepts ◽  
Dynamic Structures ◽  
High Level

Damage prognosis uses numerical and experimental responses to identify damage in structures or part of them, thus allowing the remaining structural life estimation at a high level of precision. Current methods focalize on crack identification; however, a complete methodology to estimate the remaining life of a cracked structure is less developed. A methodology is presented in this paper drawing on concepts such as wavelets transform, dynamic structures, and vibration signals for crack identification; and fracture mechanics and nonlinear optimization to obtain the remaining life. Finite element theory was applied to obtain its vibration modes. The crack was modeled as a flexural spring connected to the elements in the crack position and the crack identification was performed in the wavelet domain. Nonlinear optimization techniques and fracture mechanics concepts were used to estimate the remaining fatigue life. A numerical-experimental case study is solved to show the fundamentals of this methodology.

A Review of Recent Developments in the Mechanisms of Antifatigue Agents

1985 ◽  
Vol 58 (2) ◽  
pp. 269-283 ◽  
Author(s):  
Gerald Scott
Keyword(s):  
Structural Design ◽  
Material Design ◽  
The Past ◽  
Truck Tires ◽  
Recent Developments ◽  
Shoulder Region ◽  
Major Factors ◽  
High Level ◽  
Vulcanization Process ◽  
Made In

Abstract In spite of the remarkable advances that have been made in the engineering design of tires during the past two decades, the basic formulations used in vulcanization and protection during service have essentially remained unchanged. This is to a large extent due to two major factors: 1. The versatility of the traditional accelerated sulfur curing system which provides the necessary combination of resilience and strength with good resistance to cyclical stress. 2. The development of diarylamine antidegradants which confer a high level of thermal-oxidative and mechano-oxidative (fatigue) resistance to the rubber. Both of these developments have occurred slowly with small incremental improvements and, probably because of their success, relatively little fundamental work has been published which addresses the questions of why a polysulfide network is so resistant to fatigue and why N-sec-alkyl-N′-phenyl-p-phenylenediamines are so much more successful as antidegradants than other classes of antioxidant. It is becoming evident, however, that if tires are to withstand the increasingly demanding conditions to which they are subjected in service, much more attention must be paid to the material design as opposed to the structural design of tires. Nowhere is this more evident than in aircraft tires. Recent studies have shown that the tires of heavily laden wide-bodied aircraft reach temperatures in excess of 70°C at the relatively modest speed of 32 km/h (20 mph). Similarly, in heavy duty truck tires, temperatures over 100°C are not abnormal in the shoulder region. This leads to extensive restructurization of the fatigue resistant polysulfide network, particularly in the shoulder of the tire, to give a much weaker mono-disulfide structure. It is no coincidence then that failure normally occurs in this region. The practice of multiple retreading exacerbates the change in chemical decomposition of the rubber. It is well known to the rubber scientist that extending the vulcanization process also leads to restructurization of the rubber network from polysulfide to mono- and disulfide. This is shown typically for a HAF-black tire formulation at 140°C in Figure 1. Antidegradants have virtually no effect on anaerobic restructurization (see Figure 2), and indeed, the established antifatigue agent, IPPD (I), actually accelerates the loss of polysulfide crosslinks from the vulcanizate at 140°C. During fatiguing, on the other hand, IPPD effectively retards restructurization (see Figure 3), whereas a typical bisphenol, nonstaining antidegradant, II, has much less effect.

scholarly journals Progress in material design for biomedical applications

2015 ◽  
Vol 112 (47) ◽  
pp. 14444-14451 ◽  
Author(s):  
Mark W. Tibbitt ◽  
Christopher B. Rodell ◽  
Jason A. Burdick ◽  
Kristi S. Anseth
Keyword(s):  
Biomedical Applications ◽  
Material Design ◽  
The Body ◽  
Biological Complexity ◽  
Recent Developments ◽  
Primary Focus ◽  
Controlled Structure ◽  
High Level ◽  
Soft Biomaterials ◽  
Organ Replacement

Biomaterials that interface with biological systems are used to deliver drugs safely and efficiently; to prevent, detect, and treat disease; to assist the body as it heals; and to engineer functional tissues outside of the body for organ replacement. The field has evolved beyond selecting materials that were originally designed for other applications with a primary focus on properties that enabled restoration of function and mitigation of acute pathology. Biomaterials are now designed rationally with controlled structure and dynamic functionality to integrate with biological complexity and perform tailored, high-level functions in the body. The transition has been from permissive to promoting biomaterials that are no longer bioinert but bioactive. This perspective surveys recent developments in the field of polymeric and soft biomaterials with a specific emphasis on advances in nano- to macroscale control, static to dynamic functionality, and biocomplex materials.

Fracture mechanics in design and service: ‘living with defects’ - Statistical aspects of design: risk assessment and structural integrity

1981 ◽  
Vol 299 (1446) ◽  
pp. 111-130 ◽  
Keyword(s):  
Fracture Mechanics ◽  
Structural Reliability ◽  
Structural Integrity ◽  
Product Liability ◽  
Probabilistic Methods ◽  
Statistical Variations ◽  
Engineering Designs ◽  
Recent Developments ◽  
Quantitative Basis ◽  
And Control

Statistical variations in input parameters that affect structural reliability have historically been incorporated approximately in engineering designs by application of safety factors. Increased concerns over the injury potential and costs of licensing, insurance, field repairs or recalls, and product liability claims now demand more quantitative evaluation of possible flaws or unusual usage conditions that might result from statistical variations or uncertainties. This paper describes the basic concepts of probabilistic fracture mechanics that are used to assess and control risk. Recent developments in combined analysis methods are presented that utilize field experience data with probabilistic analysis to improve the accuracy of the structural integrity predictions. Several specific examples are described that illustrate how these probabilistic methods are used to assess risk and to provide a quantitative basis for establishing design, operation or maintenance allowables. These procedures, which realistically model the actual statistical variations that exist, can eliminate unnecessarily conservative approximations and often achieve improved reliability at reduced cost.

The police service quality in rural Taiwan

2014 ◽  
Vol 37 (3) ◽  
pp. 521-542 ◽  
Author(s):  
Chien Min Chen ◽  
Hong Tau Lee ◽  
Sheu Hua Chen ◽  
Tsung Hsien Tsai
Keyword(s):  
Service Quality ◽  
Police Officers ◽  
Empirical Support ◽  
Analytical Framework ◽  
Content Type ◽  
Police Service ◽  
Police Services ◽  
Recent Developments ◽  
Rural Police ◽  
High Level

Purpose – The purpose of this paper is to investigate the perceptions and satisfaction between police officers and citizens on Kinmen Island (of Taiwan), using an analytical framework that combines five primary dimensions and 25 corresponding determinants. Design/methodology/approach – It considers recent developments in the application of performance measures and management to public and, particularly, police services. It goes on to assess comparative rural police performance which suggests that the application of targets could ultimately serve to provide the overall satisfaction with police services. Findings – The findings of the study suggest that perceptions and satisfaction of both citizens and police staff may result in the success of the policing management, and that police managers have to satisfy their citizens with a high level of service quality based on different localities. Practical implications – From managerial perspectives, police managers should consider both the service quality and customer satisfaction constructs as determinants of behavioural intentions, based on the fact that satisfaction can be a strategic key to maintain long term relationship with citizens as it is found of significant impact on the intentional behaviour. Originality/value – This research adds empirical support to this vein of literature and has identified the five main dimensions and the 25 sub-dimensions as important constructs for police service quality.

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