A. Hernández, J. Albizuri, M.B.G. Ajuria and M.V. Hormaza
Proposes an automatic adaptive meshing scheme. Error in strain energy is directly obtained through strain energy density function (SED). Versatility of this function, in…
Abstract
Proposes an automatic adaptive meshing scheme. Error in strain energy is directly obtained through strain energy density function (SED). Versatility of this function, in comparison with that of others, is looked at in detail. Mesh enrichment method consists of a series of h‐refinement steps and concludes with a single p‐refinement step. Adds that an examination of the accuracy of the element used in the refinement procedure is made. This scheme has been implemented in ZATILAN, a FE code developed in the Department of the Mechanical Engineering of the University of the Basque Country.
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A. Hernández, J. Albizuri, R. Avilés and E. Amezua
The present paper proposes a procedure for the resolution of non‐linear structural problems. It includes a study of the reliability of the results and the adaptive meshing. The…
Abstract
The present paper proposes a procedure for the resolution of non‐linear structural problems. It includes a study of the reliability of the results and the adaptive meshing. The iterative phase of the solution of the equilibrium equations entails an adaptive strategy for updating the tangent stiffness matrix, with a control of the load step. This results in a higher rate of convergence for the iterative process. The mechanical deformation processes here considered may give rise to considerable geometric distortion in the finite elements of the mesh. If they do, the consequence will be not only that the FE analysis fails to yield precise results, but also, owing to problems deriving from the numerical ill‐conditioning, that continuation may be impractical. To facilitate the study of these results, we developed an error estimator of the flux projection type, which is based on the mechanical deformation power. It is also used as a refinement criterion for the FE mesh. Distorted meshes can be fully or partially submitted to a process of regularization based on the aspect ratio of their elements. The mesh contour may be affected by the refinement and regularization processes, for which reason we developed a procedure for its updating. This procedure is of more importance in the case of contact problems, its primary object being to avoid interpenetration. The work was done in the ZATILAN code, developed by the Department of Mechanical Engineering of the University of the Basque Country.
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Soheil Mohajerani, Duruo Huang, Gang Wang, Seyed-Mohammad Esmaeil Jalali and Seyed Rahman Torabi
This study aims to develop an efficient algorithm for generation of conforming mesh for seepage analysis through 3D discrete fracture networks (DFN).
Abstract
Purpose
This study aims to develop an efficient algorithm for generation of conforming mesh for seepage analysis through 3D discrete fracture networks (DFN).
Design/methodology/approach
The algorithm is developed based on a refined conforming Delaunay triangulation scheme, which is then validated using analytical solutions. The algorithm is well able to meet the challenge of meshing complex geometry of DFNs.
Findings
A series of sensitivity analysis have been performed to evaluate the effect of meshing parameters on steady state solution of Darcy flow using a finite element scheme. The results show that an optimized minimum internal angle of meshing elements should be predetermined to guarantee termination of the algorithm.
Originality/value
The developed algorithm is computationally efficient, fast and is of low cost. Furthermore, it never changes the geometrical structure and connectivity pattern of the DFN.
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A. Hernández, Ch. Pinto, J. Albizuri and O. Altuzarra
This paper focuses on the study of finite element (FE) analysis reliability of non‐linear planar structural problems (large strains and plasticity). In this first part, some error…
Abstract
This paper focuses on the study of finite element (FE) analysis reliability of non‐linear planar structural problems (large strains and plasticity). In this first part, some error estimators of the flux projection type have been developed over the strain power density concept. Spatial, temporal and global error estimators are proposed. From this point, the authors analyse the behaviour of different discretization error components as a function of parameters such as load step or the number of degrees of freedom of the FE model. In the second part of this work, several properties of these estimators are checked with the application to some numerical examples.
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Ch. Pinto, R. Avilés, J. Albizuri and A. Hernández
In this second part of the paper, some properties of the discretization error estimators are presented, although their theoretical background was already developed in the first…
Abstract
In this second part of the paper, some properties of the discretization error estimators are presented, although their theoretical background was already developed in the first part. Two numerical examples have been selected and will be used to check some properties of these error estimators. In addition to this, some practical conclusions will be addressed from the results and graphical output of the implemented procedure.
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Esteban Colla-De-Robertis and Sandro Navarro Castañeda
The paper aims to study the role of local institutions in the establishment of fast-food outlets in urban districts of Peru. In most urban districts, there are no fast-food…
Abstract
Purpose
The paper aims to study the role of local institutions in the establishment of fast-food outlets in urban districts of Peru. In most urban districts, there are no fast-food outlets. The authors, therefore, study the effect of institutional quality on the presence or absence of these outlets and the number of outlets if these are present.
Design/methodology/approach
The theoretical framework in which this paper is based on is the theory of agglomeration, which establishes that firms benefit from being close to each other. In particular, the paper builds on a model of market entry and competition in geographically independent local markets. An explicit expression was found for the equilibrium number of outlets (including zero) as a function of exogenous determinants of the demand for fast-food in each market, available infrastructure and institutional quality of the district’s government. Principal component analysis was used to construct measures of institutional quality based on administrative and organizational characteristics of district’s municipalities. These measures were incorporated as explanatory variables in a zero-inflated Poisson model, which is appropriate to handle count data and to accommodate excess zeros and which also allows the specification of different models for the zero part and the positive part.
Findings
Institutional quality mainly affects the presence of fast-food outlets in a district. The quality of urban development management and use of information systems are relevant. An institutional variable particularly relevant in explaining the number of outlets is the presence of an investment programming office in the municipality. The authors confirm the general hypothesis of the paper: institutions have a role in explaining both the presence and number of fast-food outlets in a district. Overall, the results of this paper suggest that institutional quality of a municipal district is related to better infrastructure, which lowers the costs of establishing outlets.
Research limitations/implications
Limitations in the availability of data at the regional and urban district level did not allow the authors to analyze other factors that affect entry decisions in the fast-food industry in Peru, such as controls to prevent corruption, legal uncertainty or crime. Another limitation was the lack of data on entry costs for each franchisee in each urban district. This forced the authors to use public infrastructure characteristics of the district as (imperfect) proxies of the entry costs.
Practical implications
The instruments of urban development management and information systems can be effective at attracting investment to a district. These tools operate partly through an indirect effect, namely, the improvement of district infrastructure, which is necessary to reduce the costs of establishing companies. There is also synergy between national government’s programs to attract investment and the good institutional quality in local governments. On the contrary, poor local institutions can be an obstacle to the successful implementation of those national programs.
Social implications
Foreign direct investment has a positive impact on the economic development of a country through knowledge spillovers. Therefore, any administrative reform to make local government practices more efficient can have an indirect impact on development.
Originality/value
Principal component analysis is a statistical tool that can be important in building good measures of institutional quality by allowing the combination of different observable characteristics into one component that can be interpreted as an operational restriction. The count model allows the use of the primary, easily observable, dependent variable, namely, the number of outlets. Finally, the two-part model makes it possible to discern the effect of institutional quality on the presence or absence of outlets and the number of outlets if these are present.
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Various routes to the synthesis of annulated and substituted pyrido[2,3‐d]pyrimidines are reported. In particular, the reactions of N‐{3‐cyano‐6‐[4(5‐oxo‐2�…
Abstract
Various routes to the synthesis of annulated and substituted pyrido[2,3‐d]pyrimidines are reported. In particular, the reactions of N‐{3‐cyano‐6‐[4(5‐oxo‐2‐ phenylhydrazono‐4,5‐dihydroimid‐azol‐1‐yl)phenyl]‐4‐ phenylpyridin‐2‐yl}formimidic ethyl ester (3) and 3‐[4‐(3‐amino‐4‐imino‐5‐phenyl‐3,4‐dihydropyrido [2,3‐d]pyrimidin‐7‐yl)phenyl]‐2‐phenyl‐5‐phenyl‐ hydrazono‐3,5‐dihydroimidazol‐4‐one (4) with a variety of reagents were investigated. The antimicrobial activity of some of the compounds obtained were evaluated and reported.
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Somrerk Chandra-Ambhorn, Neramit Krasaelom, Tummaporn Thublaor and Sirichai Leelachao
This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the…
Abstract
Purpose
This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy.
Design/methodology/approach
Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation.
Findings
The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation.
Originality/value
Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts.
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Eunice Yarce-Pinzón, Yenny Vicky Paredes-Arturo, Andrea Florez-Madroñero, Daniel Camilo Aguirre-Acevedo and Diego Mauricio Diaz-Velásquez
The purpose of this study was to determine the factors associated with functionality, a clinical criterion that could predict frailty in the elderly people in a rural context.
Abstract
Purpose
The purpose of this study was to determine the factors associated with functionality, a clinical criterion that could predict frailty in the elderly people in a rural context.
Design/methodology/approach
This project is a cross-sectional descriptive analysis of 342 adults of age >60 years who are residents of Putumayo province in Colombia. Information regarding demographic characteristics, medical history, health perception and current illness was collected. The Mini-Mental State Examination (MMSE) protocol was used to perform cognitive evaluation; the Yesavage Geriatric Depression Scale was used to establish depressive symptoms; and the Hamilton Rating Scale was used to assess anxiety level. Questionnaire was used to evaluate performance on instrumental activities of daily living that lead to functional independence [daily life questionnaire (DLQ)]. The medical outcomes study scale was used to assess social parameters.
Findings
A moderate and negative correlation was found between the DLQ score and age (r = −0.49; 95% CI: −0.57 to −0.47), whereas a positive correlation was found with education (r = 0.17; 95% CI: 0.07–0.27). Older adults with economic independence achieved a higher score in functional performance than those with economic dependence (standardized mean difference = 0.55; 95% CI: 0.33–0.77). This study observed a moderate correlation a moderate correlation between the MMSE cognitive performance (r = 0.56; 95% CI: 0.48−0.63) and the depressive symptomatology of Yesavage Scale (r = −0.36, 95% CI: −0.44 to −0.26). Finally, the structural model determined that age (r = −0.37), economic dependence (r = −0.383) and cognitive state (r = 0.309) determine the functional component.
Research limitations/implications
This study provides empirical support about older adults living in rural contexts, around the functionality variable from a multidimensional approach, highlighting the sociodemographic and cognitive variables. Consequently, the policy of social support in older adults must be oriented toward the development of a range of divergent intervention strategies.
Originality/value
The study deals with the assessment of functionality in the elderly people from an interdisciplinary approach in the rural setting which presents a greater risk of physical and socioeconomic vulnerability. Therefore, the community, the health professionals and the government entities should help implement active aging programs for this population.