1,010 research outputs found

    Učinak upotrebe urea-formaldehida modificiranog ekstraktima na emisiju formaldehida furnirske ploče

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    Formaldehyde-based adhesives are used in the forestry industry. This is because formaldehyde is inexpensive, easy to use and resistant to moisture; it also has particular mechanical effects. Formaldehyde has both advantages and disadvantages. It is known that various diseases such as lung cancer occur in humans as a result of the release of formaldehyde into the air during and after board production. In this study, a urea formaldehyde glue mixture was prepared by using four different fillers (extract of maritime pine (Pinus pinaster) and elm (Ulmus glabra) bark, extract of hazelnut (Corylus avellana) husk and acorn tannins) at two different ratios. The bonding shear strength of pine (Pinus sylvestris) and spruce (Picea orientalis) plywood produced with urea formaldehyde adhesive was tested according to EN 314-1 standard. All plywood, except the plywood with acorn tannin, met the requirements of the standard. A formaldehyde emission test of the plywood was carried out in accordance with EN 713-3 standard. With this approach, it is possible to quickly determine formaldehyde emissions. Experimental results were obtained for subsequent measurements, including chamber tests. It was observed that the elm bark extract reduced the formaldehyde emission of pine plywood by 40 %, while other fillers reduced it by 3-37 %.U drvoprerađivačkoj industriji upotrebljavaju se ljepila na bazi formaldehida zato što je taj aldehid jeftin, jednostavan za uporabu, otporan na vlagu i ima posebne mehaničke učinke. Formaldehid ima određenih prednosti i nedostataka. Poznato je da se u ljudi koji rade u drvoprerađivačkoj industriji pojavljuju različite bolesti poput raka pluća, što može biti posljedica ispuštanja formaldehida u zrak tijekom i nakon proizvodnje ploča. Za ovo je istraživanje pripremljena smjesa urea-formaldehidnog ljepila dodavanjem četiriju različitih punila: ekstrakta kore primorskog bora (Pinus pinaster) i brijesta (Ulmus glabra), ekstrakta ljuske lješnjaka (Corylus avellana) i tanina žira u dva različita omjera. Posmična čvrstoća furnirske ploče od borovine (Pinus sylvestris) i smrekovine (Picea orientalis), proizvedene uporabom urea-formaldehidnog ljepila, ispitana je prema normi EN 314-1. Sve furnirske ploče, osim onih s taninom iz žira, zadovoljile su zahtjeve norme. Ispitivanje emisije formaldehida iz furnirskih ploča provedeno je prema normi EN 713-3. Tim je pristupom moguće brzo odrediti emisije formaldehida. Dobiveni su eksperimentalni rezultati za naknadna mjerenja, uključujući ispitivanje u komori. Primijećeno je da je ekstrakt kore brijesta smanjio emisiju formaldehida furnirske ploče od borovine za 40 %, dok su ostala punila smanjila tu emisiju za 3 – 37 %

    Effect of Ultrasonic Treatment in the Static and Dynamic Mechanical Behavior of AZ91D Mg Alloy

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    The present study evaluates the effect of high-intensity ultrasound (US) in the static and dynamic mechanical behavior of AZ91D by microstructural modification. The characterization of samples revealed that US treatment promoted the refinement of dendrite cell size, reduced the thickness, and changed the β-Mg17Al12 intermetallic phase to a globular shape, promoted its uniform distribution along the grain boundaries and reduced the level of porosity. In addition to microstructure refinement, US treatment improved the alloy mechanical properties, namely the ultimate tensile strength (40.7%) and extension (150%) by comparison with values obtained for castings produced without US vibration. Moreover, it is suggested that the internal friction, enhanced by the reduction of grain size, is compensated by the homogenization of the secondary phase and reduction of porosity. It seems that by the use of US treatment, it is possible to enhance static mechanical properties without compromising the damping properties in AZ91D alloys.This research was supported by FEDER/COMPETE funds and by national funds through FCT-Portuguese Foundation for Science and Technology and was developed on the aim of Post-Doctoral grant SFRH/BPD/76680/2011. Also, this work has been supported by the FCT in the scope of the project: UID/EEA/04436/2013.info:eu-repo/semantics/publishedVersio

    The effects of perceived organisational support on employees\u27 affective outcomes: evidence from the hotel industry

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    Previous studies mainly analysed the relationship between perceived organisational support and organisational commitment in a direct way. Limited studies of tourism, however, have found that job satisfaction is a mediator variable in the relationship between perceived organisational support and organisational commitment. The aim of this study is, (i) to analyse the effect of organisational support on job satisfaction, (ii) to analyse the effect of organisational support on the dimensions of organisational commitment, (iii) to analyse the effect of job satisfaction on the dimensions of organisational commitment, and (iv) to analyse the mediating effect of job satisfaction on the relationship between perceived organisational support and dimensions of organisational commitment based on an empirical study. The relationship between the variables was analysed by using a multivariate data analysis. Besides this, in the study, the mediating effect of job satisfaction on the relationship between perceived organisational support and the dimensions of organisational commitment was analysed by the technique recommended by Baron and Kenny (1986) and the Sobel test. The findings indicated that perceived organisational support had a significant positive effect on job satisfaction, affective, normative and continuous commitment. Job satisfaction had a significant positive effect on affective, normative and continuous commitment as well. Besides this, job satisfaction played a partial mediating role between perceived organisational support and dimensions of organisational commitment. Implications were presented for hotel managers who want to keep and encourage their employees to work in the hotel industry

    Skin avulsion injury during endotracheal tube extubation – case report of an unusual complication

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    We report a geriatric case with a full-thickness skin avulsion injury during extubation due to a tube securing tape used to fixate the endotracheal tube. The avulsed skin was sutured back to its original place. Based on this single geriatric patient, we recommend anesthesiologists/anesthetists and surgeons be aware of the potential risk of avulsing the skin with tape during a standard extubation procedure. This may especially occur in geriatric patients who have age related changes as decreased elasticity and resistance to shearing forces that predispose the skin to get traumatized easily

    Software product quality metrics : a systematic mapping study

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    In the current competitive world, producing quality products has become a prominent factor to succeed in business. In this respect, defining and following the software product quality metrics (SPQM) to detect the current quality situation and continuous improvement of systems have gained tremendous importance. Therefore, it is necessary to review the present studies in this area to allow for the analysis of the situation at hand, as well as to enable us to make predictions regarding the future research areas. The present research aims to analyze the active research areas and trends on this topic appearing in the literature during the last decade. A Systematic Mapping (SM) study was carried out on 70 articles and conference papers published between 2009 and 2019 on SPQM as indicated in their titles and abstract. The result is presented through graphics, explanations, and the mind mapping method. The outputs include the trend map between the years 2009 and 2019, knowledge about this area and measurement tools, issues determined to be open to development in this area, and conformity between conference papers, articles and internationally valid quality models. This study may serve as a foundation for future studies that aim to contribute to the development in this crucial field. Future SM studies might focus on this subject for measuring the quality of network performance and new technologies such as Artificial Intelligence (AI), Internet of things (IoT), Cloud of Things (CoT), Machine Learning, and Robotics.publishedVersio

    El efecto de la diversidad e independencia del consejo de administración en la existencia de un comité de sostenibilidad

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    The purpose of this study was to enhance the understanding of the factors determining the existence of a “Corporate Social Responsibility” (CSR) committee on the board. Focusing the attention on board composition, this paper explores how female directors influence the existence of a CSR committee, and how this effect can be moderated by the independence of board members. To be able to test the aims of the study, an international sample of analysis of 4,168 firm-year observations from 2012 to 2016 was used, proposing several models for panel data. The findings revealed that female directors exert a positive influence on the existence of a CSR committee, although this commitment is limited when in addition to women, they are independent directors on the board. Therefore, it can be said that board gender diversity and board independence are not complementary mechanisms that favour the existence of a specific committee on CSR. This study is one of a limited number of studies to focus on the antecedents of existence of a CSR committee in firms. In addition, the study obtains benefit by considering the independence of board of directors as a moderating variable on the relationship female directors-sustainability. In contrast with previous studies based on the cross-sectional data from a single country, the data set of the current study includes a panel data comprising of a period between 2012 and 2016 and an international sample from 44 countries in six continents.El objetivo de este estudio es reforzar el conocimiento sobre los factores que determinan la existencia de un comité de sostenibilidad en el consejo de administración. Centrando el interés en la composición del Consejo, este trabajo explora como las mujeres consejeras influyen en la existencia de un comité de sostenibilidad; además, este estudio también analiza si este efecto puede ser moderado por la independencia de los consejeros. Con el objetivo de testar estos objetivos, se hace uso de una muestra de análisis internacional compuesta por 4.168 observaciones para el periodo 2012-2016 proponiendo diversos modelos de regresión para datos de panel. Los resultados confirman que las mujeres consejeras ejercen un efecto positivo, favoreciendo la creación de un comité de sostenibilidad, aunque este compromiso está limitado cuando además de mujeres, éstas son consejeras independientes. Por lo tanto, podemos decir que la diversidad de género y la independencia no actúan como mecanismos complementarios que favorezcan la creación de un comité de sostenibilidad. Este estudio es uno de los pocos estudios previos que se centran en analizar los antecedentes de la existencia de un comité de sostenibilidad. Además, este trabajo añade valor a la evidencia previa, considerando la independencia del consejo como un factor de moderación a tener en cuenta en la relación mujeres- sostenibilidad. A diferencia de estudios previos centrados en un único país, el conjunto de datos analizados en este estudio comprende una base de datos de panel de empresas para el periodo comprendido entre 2012 y 2016 y una muestra internacional de operando en 44 países en seis continentes

    High-skilled female immigrants: career strategies and experiences

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    © 2018, Emerald Publishing Limited. Purpose: The purpose of this paper is to uncover career-related issues that high-skilled female immigrants face and their strategies for rebuilding their careers upon migration for a diverse range of reasons including following a spouse, furthering education and self-initiated expatriation. Design/methodology/approach: Using grounded theory to explore this topic, the authors performed 14 in-depth interviews with female immigrants that fit pre-determined inclusion criteria for high-skilled (e.g. educated, gainfully and professionally employed). The study context of immigration is the USA, and the authors performed interviews with high-skilled immigrants from Turkey – an underrepresented nation in the US migrant population. Findings: Content analysis of in-depth interviews revealed five primary theoretical themes that captured the career experiences of these individuals: non-linear career entry, career orientation, strong commitment and will to succeed, socialization patterns at work and support network. Integrating these findings with theories on adult learning, the authors developed an experiential learning model of career reconstruction among high-skilled immigrants. Originality/value: This study contributes to the global mobility literature by developing an experiential learning theory of careers and taking a gendered perspective to the career experiences of high-skilled female immigrants. It answers the questions: what are the individual and situation factors associated with career success among high-skilled female immigrants? and what is the process that high-skilled immigrants go through to rebuild their careers

    Investigation of the Problem Solving and Excellence Levels of the Secondary School Students Who Do Sports and Does Not

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    In this study, it was aimed to compare the problem solving and perfectionism levels of the students who do sports and do not sports in terms of various variables, and to determine the correlation between problem solving and their perfectionism. In the province of Among the competitions between secondary schools in the 2018-2019 academic year, Milas district of Muğla province, 171 sports students between the ages of 13-15, whose sports age is at least 2 years, were randomly selected among the sports students. SPSS 22.0 statistics program was used in the analysis of the data. After the descriptive analyzes were made on the data, as the results of the Kolmogorov-Simirnov normality test performed by comparing the scores of the participants were not normal, the difference between the groups was examined by applying the Mann-Whitney test, which is one of the non-parametric tests. The "Mann-Whitney U" test was used to determine the differences between the groups. Statistical analyzes were tested at 95% confidence level, p<0.05 values were considered statistically significant. Under the "spearman's rho" test for the correlation between perfectionism and problem-solving scale. As a result, although the perfectionism and problem solving levels of the students who do and do not do sports have a meaningful result, the effect of doing sports varies according to gender; We can say that there is a positive correlation in the sub-dimensions of perfectionism and problem solving skills

    Correlating low energy impact damage with changes in modal parameters: a preliminary study on composite beams

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    This paper is an experimental study of the effects of multi-site damage on the vibration response of a composite beam damaged by low energy impact. The variation of the modal parameters with different levels of impact energy and density of impact is studied. Specimens are impacted symmetrically in order to induce a global rate of damage. A damage detection tool Damage Index is introduced in order to verify the estimation of damping ratios. Design of Experiments is used to establish the sensitivity of both energy of impact and density of damage. The DOE analysis results (using natural frequency only) indicate that impact energy for 2nd, 3rd and 4th bending modes is the most significant factor contributing to the changes in the modal parameters for this kind of symmetrical dynamic test

    The effect of grain direction on lateral nail strength and thermal conductivity of structural plywood panels

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    The aim of study was to determine the effects of grain direction on the lateral nail strength and thermal conductivity of structural plywood panels. Experiment were made with plywood manufactured from Scots pine, maritime pine and black pine. A rotary peeler with a maximum horizontal holding capacity of 80 cm was used for veneer manufacturing. The highest values of max load (2,17 kN), stiffness (2,52 kN/ mm) and displacement at ultimate load (36,8 mm) were obtained from C1PR group panels manufactured from black pine. Also, it was determined the mechanical properties in perpendicular to grain were higher than those in parallel to grain. The black pine panels gave highest average thermal conductivity value (0,168 W/mK), while that of Scots pine was lowest (0,145 W/mK). Thermal conductivity of panels in perpendicular to the grain of main axis of plywood was always found to be higher than the values obtained from measurements parallel to the grain
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