scholarly journals Long-Term Reliability of Brittle Materials: The Issue of Crack Arrest

2003 ◽  
Vol 125 (3) ◽  
pp. 333-340 ◽  
Author(s):  
Yann Charles ◽  
Franc¸ois Hild ◽  
Ste´phane Roux
Keyword(s):  
Slow Crack Growth ◽  
Brittle Materials ◽  
Crack Arrest ◽  
Propagation Model ◽  
Weakest Link ◽  
Different Types ◽  
Thin Walled Tube ◽  
Thin Walled

In structures containing brittle materials, residual and/or heterogenous stresses may prevent cracks to propagate up to failure. Consequently, for such structures, crack arrest has to be accounted for and a weakest link hypothesis may not be applicable. A probabilistic crack propagation model is derived to describe instantaneous or delayed arrest phenomena. A time-dependent regime is induced by slow crack growth experienced by ceramics and glasses. A general expression is obtained in which instantaneous up to infinite propagation times can be modeled in a unified way. The results are illustrated on a case study dealing with propagation of cracks in a thin walled tube submitted to a temperature gradient through its thickness. Different types of propagation/arrest regimes can be identified.

scholarly journals Case Study on Fire Resistance of Sandwiches for Means of Transport

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 207
Author(s):  
Pavel Koštial ◽  
Zora Koštialová Jančíková ◽  
Robert Frischer
Keyword(s):  
Fire Resistance ◽  
Fire Protection ◽  
Public Transport ◽  
Hybrid Vehicles ◽  
Safety Requirements ◽  
Different Types ◽  
Aluminum Honeycomb ◽  
Heat Loads

These days there are undeniably unique materials that, however, must also meet demanding safety requirements. In the case of vehicles, these are undoubtedly excellent fire protection characteristics. The aim of the work is to experimentally verify the proposed material compositions for long-term heat loads and the effect of thickness, the number of laminating layers (prepregs) as well as structures with different types of cores (primarily honeycomb made of Nomex paper type T722 of different densities, aluminum honeycomb and PET foam) and composite coating based on a glass-reinforced phenolic matrix. The selected materials are suitable candidates for intelligent sandwich structures, usable especially for interior cladding applications in the industry for the production of means of public transport (e.g., train units, trams, buses, hybrid vehicles).

scholarly journals Amelogenesis imperfecta: A case series

2021 ◽  
Vol 7 (3) ◽  
pp. 145-148
Author(s):  
Jijin M J ◽  
Thabsheera P P ◽  
Mohamed Labeeb K P ◽  
Anjana R
Keyword(s):  
Dental Treatment ◽  
Tooth Development ◽  
Genetic Disorders ◽  
Case Series ◽  
Gene Mutations ◽  
Amelogenesis Imperfecta ◽  
Clinical Case Study ◽  
Different Types

Amelogenesis imperfecta (AI) refers to a group of rare genetic disorders that involve tooth development and that are passed down through families as a dominant trait. This condition is characterized by abnormal enamel formation caused by gene mutations that alter the quality and/or quantity of enamel. This dental problem can impact both primary and permanent dentition, varies among affected individuals, and results in esthetic and functional problems. The treatment planning for patients with AI is related to many factors, including the age of the patient, the type and severity of the disorder, intraoral conditions, and the socioeconomic status of the patient. It is crucial to plan a proper remedy, which requires collaboration among dental specialties to execute comprehensive dental treatment in order to provide a long-term solution with adequate esthetics. This clinical case study looks at three different types of amelogenesis imperfecta patients.

scholarly journals Variations in power of opinion leaders in online communication networks

2018 ◽  
Vol 5 (10) ◽  
pp. 180642 ◽  
Author(s):  
Mohsin Adalat ◽  
Muaz A. Niazi ◽  
Athanasios V. Vasilakos
Keyword(s):  
Communication Networks ◽  
Online Discussion ◽  
Online Communication ◽  
Communication Patterns ◽  
Opinion Leaders ◽  
Link Type ◽  
Online Social Media ◽  
Different Types

Online social media has completely transformed how we communicate with each other. While online discussion platforms are available in the form of applications and websites, an emergent outcome of this transformation is the phenomenon of ‘opinion leaders’. A number of previous studies have been presented to identify opinion leaders in online discussion networks. In particular, Feng (2016 Comput. Hum. Behav. 54 , 43–53. ( doi:10.1016/j.chb.2015.07.052 )) has identified five different types of central users besides outlining their communication patterns in an online communication network. However, the presented work focuses on a limited time span. The question remains as to whether similar communication patterns exist that will stand the test of time over longer periods. Here, we present a critical analysis of the Feng framework both for short-term as well as for longer periods. Additionally, for validation, we take another case study presented by Udanor et al. (2016 Program 50 , 481–507. ( doi:10.1108/PROG-02-2016-0011 )) to further understand these dynamics. Results indicate that not all Feng-based central users may be identifiable in the longer term. Conversation starter and influencers were noted as opinion leaders in the network. These users play an important role as information sources in long-term discussions. Whereas network builder and active engager help in connecting otherwise sparse communities. Furthermore, we discuss the changing positions of opinion leaders and their power to keep isolates interested in an online discussion network.

Medicines education at home – A case study in Finland

2017 ◽  
Vol 76 (8) ◽  
pp. 986-999 ◽  
Author(s):  
Johanna Hokkanen ◽  
Anna-Liisa Elorinne ◽  
Katri Hämeen-Anttila ◽  
Tuula Keinonen
Keyword(s):  
Family Member ◽  
Quantitative Data ◽  
Qualitative Data ◽  
Medicine Use ◽  
Mixed Methods Case Study ◽  
Different Types ◽  
Consumption Practices ◽  
Medicine Cabinet

Background: Educating children about medicines and medicine use is part of health education and is often seen as parents’ responsibility. However, to date, little research has been conducted on medicines education as provided in the home. Objective: To explore (1) parents’ attitudes towards medicines, (2) medicines education practices in the home and (3) the interaction in medicines education between the home and at school. Design: Mixed-methods case study. Setting: Pupils and their parents in one comprehensive school in Finland. Method: Before an educational intervention with Year 4 (aged 10–11 years) and Year 7 (aged 13–14 years) students, parents completed a background survey concerning their perceptions, beliefs and knowledge of medicines ( n = 250). Following the intervention, interviews with 12 mothers and 12 children, and medicine cabinet studies ( n = 10) were conducted. Quantitative data were analysed using K-mean cluster analysis to see whether respondents could be divided into different clusters based on their attitudes towards medicines. Qualitative data were analysed using theory-guided content analysis to obtain a picture of home medicines education. Results: Participants, mostly mothers, were divided into different types of medicine educators, whose attitudes towards medicines were either positive or neutral. Medicine consumption practices varied between families, but medicines were usually discussed when the child, a family member, a relative or a friend had a long-term illness; when a family member was suffering from a sickness; and while taking a medicine. In general, interaction between the home and the school was rather limited. Conclusion: The majority of mothers exhibited a strong reliance on public systems of health care. Greater interaction between schools and the home is needed in Finnish medicines education.

scholarly journals Long-term avalanche hazard assessment with a Bayesian depth-averaged propagation model

2010 ◽  
Vol 56 (198) ◽  
pp. 563-586 ◽  
Author(s):  
N. Eckert ◽  
M. Naaim ◽  
E. Parent
Keyword(s):  
Estimation Algorithm ◽  
Propagation Model ◽  
Hazard Mapping ◽  
Model Identifiability ◽  
Pressure Distributions ◽  
Dynamical Simulations ◽  
Recent Developments ◽  
Avalanche Flow

AbstractWhile performing statistical–dynamical simulations for avalanche predetermination, a propagation model must reach a compromise between precise description of the avalanche flow and computation times. Crucial problems are the choice of appropriate distributions describing the variability of the different inputs/outputs and model identifiability. In this study, a depth-averaged propagation model is used within a hierarchical Bayesian framework. First, the joint posterior distribution is estimated using a sequential Metropolis–Hastings algorithm. Details for tuning the estimation algorithm are provided, as well as tests to check convergence. Of particular interest is the calibration of the two coefficients of a Voellmy friction law, with model identifiability ensured by prior information. Second, the point estimates are used to predict the joint distribution of different variables of interest for hazard mapping. Recent developments are employed to compute pressure distributions taking into account the rheology of snow. The different steps of the method are illustrated with a real case study, for which all possible decennial scenarios are simulated. It appears that the marginal distribution of impact pressures is strongly skewed, with possible high values for avalanches characterized by low Froude numbers. Model assumptions and results are discussed.

scholarly journals Temporality of agency in regional development

2021 ◽  
pp. 096977642110288
Author(s):  
Markus Grillitsch ◽  
Bjørn Asheim ◽  
Hjalti Nielsen
Keyword(s):  
Regional Development ◽  
Economic Geography ◽  
Regional Studies ◽  
Distant Future ◽  
Different Types ◽  
Short And Long Term ◽  
Long Term Consequences ◽  
Development Outcomes

The temporality of agency plays a fundamental role in regional development but has received little attention in economic geography and regional studies. This paper zooms in on two aspects of temporality: the temporality of intentions and the temporality of consequences. The former refers to actors’ perception and valuation of opportunities in the near and distant future, whereas the latter refers to the short- and long-term consequences of actions. This paper studies the temporality of agency in the context of regional development. It investigates how short- and long-term intentions motivate different types of agency, how different types of agency affect short- and long-term regional development outcomes and which conditions enable or constrain different types of agency. We illustrate our arguments with an in-depth case study covering the regional development of a labour market in Norway over the last 20 years.

IMPLEMENTATION OF OPEN INNOVATION STRATEGIES: A BUYER–SUPPLIER PERSPECTIVE

2014 ◽  
Vol 18 (06) ◽  
pp. 1440013 ◽  
Author(s):  
DAVID T. ROSELL
Keyword(s):  
Open Innovation ◽  
Short Term ◽  
Knowledge Based ◽  
Trade Offs ◽  
Different Types ◽  
Multiple Case ◽  
Innovation Strategies ◽  
Opening Up

The open innovation concept has been discussed for more than a decade. However, there are relatively few studies related to implementation of open innovation. Barriers of implementation have been identified, but they are not related to the external knowledge searched for. This multiple-case study adds to current understanding of implementing open innovation strategies by focusing on the cooperation and coordination challenges when opening up for different types of supplier knowledge. Possible solutions and trade-offs between short-term benefits and long-term goals are presented that take into consideration the character of knowledge and human behavior. By applying theories such as knowledge-based view and transaction cost theories on empirical findings, different explanations are sought that bring new insights into managing open innovation.

scholarly journals Passive Road Safety Systems - Case Study Of Road Section Banja Luka - Prnjavor (M16, M16.1)

2018 ◽  
Vol 3 (1-2) ◽  
Author(s):  
Ognjen Sančanin ◽  
Danislav Drašković ◽  
Demeter Prislan
Keyword(s):  
Road Safety ◽  
Traffic Accident ◽  
The Road ◽  
Road Section ◽  
Different Types ◽  
Banja Luka ◽  
Safety Systems

In this paper, the authors will show the influence of roadside objects on road safety on the Banja Luka - Prnjavor section. Roadside objects have a major impact on the weight of a traffic accident because they represent direct obstacles to the wandering vehicle, which in most cases will be stopped by a collision in one of them in the immediate vicinity of the road. Roadside objects can be of different types and constructions, concrete poles, public lighting poles, trees, inadequately installed rebound fences and unprotected petrol stations are only some of them. Therefore, the essence of this paper is to spot possible roadside objects on the observed road section, categorize them, and make suggestions for short, medium and long term improvements.

Modelling Cleavage Fracture in High Strength Steels and Their Welds

2005 ◽  
Vol 482 ◽  
pp. 171-174 ◽  
Author(s):  
Rodolfo-Martín Rodriguez ◽  
I. Ocaña-Arizcorreta ◽  
A. Martín-Meizoso
Keyword(s):  
Fracture Toughness ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
High Yield ◽  
Matrix Interface ◽  
High Yield Strength ◽  
Weakest Link ◽  
Different Types ◽  
Fracture Nucleation

High strength steels are characterized by their high yield strength, but to guarantee a safe design, a sufficiently large fracture toughness value is also required. In this paper, the fracture toughness of three high strength steels (sy= 460-890 MPa) and their welds has been studied at low temperatures. Experimental results have been used to validate a statistical “weakest link” fracture model. The model takes into account the possibility of fracture nucleation in different types of particles and brittle phases, as well as the crack-arrest factors at the different microstructural barriers (particle-matrix interface and grain boundaries).

scholarly journals The impact of global trends on Serbian foreign trade

Industrija ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 81-95
Author(s):  
Nataša Stanojević ◽  
Slobodan Kotlica
Keyword(s):  
Linear Regression ◽  
Foreign Trade ◽  
Global Economy ◽  
Global Trends ◽  
Different Types ◽  
To Come ◽  
The Impact ◽  
Global Indicators

This paper analyzes the current key processes in the global economy: decline in international trade, rising protectionism and shortening of global production chains. The specific aim is to determine the effects of these global trends on Serbian foreign trade. The proposed hypotheses are 1) Decline in the volume of Serbian foreign trade can be expected to be sharper than global indicators and 2) The reduced volume of trade both in Serbia and globally will tend to continue for many years to come. Using statistical analysis for different types of data, linear regression and case study, the research has confirmed the first hypothesis. The coefficients obtained bz linear regression were applied to the WTO projections for global trade in 2020 and 2021. It was found that the expected decline in Serbia's foreign trade is almost twice the world average. The second hypothesis is proven by the analysis of the economic causes of the main global trends, which have proven to be structural to the greatest extent, hence long-term.

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