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Article
Publication date: 1 September 1996

Teodiano Freire Bastos, L. Calderón, J.M. Martín and R. Ceres

Evaluates the applicability of ultrasonic sensors in a welding environment and reports on experimental measurements carried out with a sensory head containing ultrasonic…

Abstract

Evaluates the applicability of ultrasonic sensors in a welding environment and reports on experimental measurements carried out with a sensory head containing ultrasonic transducers with different frequencies. Analyses the effects on the sensors of factors such as noise, temperature and shielding gas flow and concludes by suggesting appropriate protective measures for the sensors for them to operate effectively in a welding environment.

Details

Sensor Review, vol. 16 no. 3
Type: Research Article
ISSN: 0260-2288

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Book part
Publication date: 21 August 2017

Victoria E. Díaz, Pierre Mercier and Celine Pinsent

This chapter presents a new conceptual framework of institutional research (IR). The framework refines previously studied dimensions of IR and integrates them into the…

Abstract

This chapter presents a new conceptual framework of institutional research (IR). The framework refines previously studied dimensions of IR and integrates them into the higher order concept of knowledge management. Previously studied dimensions of IR include the institution’s organizational sectors (e.g., academic, human resources), the functions for which information is used (e.g., operations, strategic management), and the resources supporting IR (e.g., technology, funding). The framework innovates by specifying what competencies are required to carry out IR activities and how to assign a level of development to each competency. This operationalization permits the creation of an assessment tool enabling us to move from general and intuitive statements about development to specific and behavioral levels which are actionable. The framework formulation was validated with a group of IR experts in Chile. The framework can be used to assess one institution, to compare an institution to a peer group, or to compare groups of institutions at the regional, national, or international levels.

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Theory and Method in Higher Education Research
Type: Book
ISBN: 978-1-78743-222-2

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Article
Publication date: 6 May 2021

Carmenza Gallego and Gregorio Calderón Hernández

This paper aims to comprehend organizational transformation (OT) as a permanent, continuous and iterative system, which integrates large transformations that, in turn…

Abstract

Purpose

This paper aims to comprehend organizational transformation (OT) as a permanent, continuous and iterative system, which integrates large transformations that, in turn, require smaller, additional transformations. For OT implementation, a conceptual model is proposed, called the four orders of OT.

Design/methodology/approach

Case study with a qualitative approach, used critical incident interviews, which were applied to describe both successful and unsuccessful events. Participants were chosen by convenience, and information was processed with Nvivo software.

Findings

The Colombian family holding studied was founded in 1974, and in its 47 years of existence, has implemented important transformations in its three companies. These showcase the four types of OT proposed, although third order support has been applied most often. The events that triggered said transformations are mainly of exogenous character, and broad responsibility was found on both the upper management and work team levels for implementation processes. This was also found for the indicator use and the various planning approaches used, depending upon the transformation type.

Practical implications

Future research is required, so as to refine and validate the conceptual OT model proposed in other types of companies and development contexts. The proposed construct permits company managers to design and more efficiently manage transformations, while satisfying the diverse orders proposed in the theoretical model.

Originality/value

An integrative conceptual model called “the four orders of OT” is proposed and validated in a Colombian family businesses group, which is composed of three companies.

Details

Journal of Accounting & Organizational Change, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1832-5912

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Article
Publication date: 1 March 1991

J.L. Marshall, J. Calderon and J. Sees

A mechanical and microstructural study was performed of 43/43/14 tin/lead/bismuth solder. This alloy melts lower than the commonly used tin/lead solders and therefore…

Abstract

A mechanical and microstructural study was performed of 43/43/14 tin/lead/bismuth solder. This alloy melts lower than the commonly used tin/lead solders and therefore holds promise as a useful material in two‐step soldering processes or in processes with thermally sensitive components. Mechanical testing of 43/43/14 tin/lead/bismuth showed a strength comparable to that of tin/lead solders but increased creep rate. Microstructural analysis (scanning electron microscopy/energy dispersive X‐ray) exhibited the same mechanism of fatigue as for tin/lead solders, viz., heterogeneous coarsening. Thermocyclic fatigue demonstrated that the long‐term reliability of 43/43/14 tin/lead/bismuth is comparable to that of tin/lead solders.

Details

Soldering & Surface Mount Technology, vol. 3 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 6 November 2017

A.K. Larios-Galvez, J. Porcayo-Calderon, V.M. Salinas-Bravo, J.G. Chacon-Nava, Jose Gonzalo Gonzalez-Rodriguez and L. Martinez-Gomez

The purpose of this research paper was to investigate the use of methanolic extract of Salvia hispanica (S. hispanica) as a green corrosion inhibitor for bronze in a…

Abstract

Purpose

The purpose of this research paper was to investigate the use of methanolic extract of Salvia hispanica (S. hispanica) as a green corrosion inhibitor for bronze in a simulated acid rain solution.

Design/methodology/approach

Extract of S. hispanica was used as a green corrosion inhibitor for bronze in simulated acid rain solution. Electrochemical techniques such as potentiodynamic polarization curves, electrochemical impedance spectroscopy and electrochemical noise were used. Parameters such as polarization, charge transfer and noise resistance (Rp, Rct and Rn, respectively) were calculated.

Findings

Results showed that the extract acts as a good, anodic type of inhibitor. The inhibitor efficiency increased with increasing its concentration up to 400 ppm, decreasing beyond this concentration. Efficiency also increased with an increase in the immersion time. The inhibition was due to the adsorption of components found in the S. hispanica extract following a Langmuir adsorption isotherm.

Practical implications

S. hispanica extract can be used as a corrosion inhibitor for bronze in acid rain solution.

Originality/value

This study provides new information on the inhibition features of S. hispanica under specific conditions. This eco-friendly inhibitor could find applications to protect bronze exposed to polluted urban atmospheres.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 6
Type: Research Article
ISSN: 0003-5599

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Book part
Publication date: 26 August 2019

Jorge M. Gorostiaga and Óscar Espinoza

In this chapter, the authors analyze the academic field of comparative education in Spanish speaking Latin America as a contested construction both in epistemological and…

Abstract

In this chapter, the authors analyze the academic field of comparative education in Spanish speaking Latin America as a contested construction both in epistemological and political dimensions. First, the authors provide a brief historical account of the origin and development of comparative education in the region since the nineteenth century. Next, they focus on the current state of the field by addressing three aspects: (1) the institutional basis, specially the development of comparative education societies; (2) an account of the contributions of international organizations, both in terms of studies that have been recently conducted and of the development of data bases; and (3) an analysis of prevailing topics as well as theoretical and methodological approaches in a sample of articles published during the 2010-2017 period. The authors conclude by summarizing the main aspects of the current situation, and pointing to future epistemological and political challenges for the field in the region.

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Comparative and International Education: Survey of an Infinite Field
Type: Book
ISBN: 978-1-78743-392-2

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Article
Publication date: 1 January 1993

J. Seyyedi

An empirical study was conducted to determine the thermal fatigue behaviour of 1.27 mm pitch, J‐bend and gullwing surface mount solder joints, manufactured with four…

Abstract

An empirical study was conducted to determine the thermal fatigue behaviour of 1.27 mm pitch, J‐bend and gullwing surface mount solder joints, manufactured with four low‐temperature solders. Selected solder alloys were: 58Bi‐42Sn (wt %), 43Sn‐43Pb‐14Bi, 52ln‐48Sn and 40ln‐40Sn‐20Pb. Accelerated thermal cycling was used in conjunction with metallographic analysis and mechanical (pull) strength measurement to test their behaviour. The relative merit of each solder composition was determined by comparing it with 63Sn‐37Pb solder, subjected to identical testing conditions. The strength decreased linearly with increased number of thermal cycles for gullwing solder joints of all four solder alloys. The fatigue lifetime was relatively longer for 58Bi‐42Sn and 40ln‐40Sn‐20Pb than for other alloys, but significantly lower than that obtained with 63Sn‐37Pb solder. No discernible degradation of strength was observed with the J‐bend solder joints of any solder alloy, even after the completion of 6000 thermal cycles. Thermal fatigue resistance of the latter joints was attributed to a more favourable coefficient of thermal expansion (CTE) mismatch. Solder joint cracking occurred only in gullwing components soldered with 52ln‐48Sn, 40ln‐40Sn‐20Pb and 43Sn‐43Pb‐14Bi alloys, after 1000 or 2000 thermal cycles. The crack initiated on the outside surface of the solder fillet, and appeared to propagate through both phases of the microstructure. The stress‐induced heterogeneous coarsening of the microstructure was evident only with 43Sn‐43Pb‐14Bi solder, although not as prevalent as that usually observed with eutectic Sn‐Pb solder. Fatigue cracks were absent from solder joints of 58Bi‐42Sn and 63Sn‐37Pb alloys.

Details

Soldering & Surface Mount Technology, vol. 5 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 December 1997

J.L. Marshall and J. Calderon

A series of composite solders in 63/37 Sn/Pb was prepared: Cu6 Sn5 (10, 20,30 wt%); Cu3 Sn (10, 20, 30 wt%); Cu (7.6 wt%); Ag (4 wt%); and Ni (4 wt%). These composite…

Abstract

A series of composite solders in 63/37 Sn/Pb was prepared: Cu6 Sn5 (10, 20, 30 wt%); Cu3 Sn (10, 20, 30 wt%); Cu (7.6 wt%); Ag (4 wt%); and Ni (4 wt%). These composite solders were prepared by two procedures: (A) admixture with solder paste; and (B) admixture with molten solder. The original particulates and the final composite solders were analysed and characterised by SEM (scanning electron microscopy) EDX (energy dispersive X‐ray), and ESCA (electron spectroscopy for chemicals analysis); or XPS (X‐ray photoelectron spectroscopy). A variety of morphological characterisations, intermetallics and porosities were noted. Good wetting was noted in all cases, and porosity was greater for method (A). The particulates all exhibited excellent binding to the solder matrix.

Details

Soldering & Surface Mount Technology, vol. 9 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 19 October 2010

Nelson L. Lammoglia, Camilo Olaya, Jorge Villalobos, Juan P. Calderón, Juan A. Valdivia and Roberto Zarama

The paper considers model‐based management and, based on it, proposes a heuristic‐based management. This paper aims to assert that heuristic‐based management, for complex…

Abstract

Purpose

The paper considers model‐based management and, based on it, proposes a heuristic‐based management. This paper aims to assert that heuristic‐based management, for complex systems, a process of free variation, of pairs of models and actions – called organisational strategies, maximizes the chances of improving the system's performance in open environments.

Design/methodology/approach

A conception of complex systems are introduced and characterized as open and self‐organising systems. Then, the proposal to heuristically use pairs of models and actions, called organisational strategies, to manage social systems based on evolutionary thought is supported. Subsequently, a computational experiment is proposed to show that, even in a simple framework, variation processes are required.

Findings

The paper shows that two processes may be required to preserve self‐organising systems. This finding indicates that variation and selection processes, related to evolutionary thought, are necessary for managers to deal with complex systems interacting with complex environments. Finally, it is shown that, even in simple computational environments, variation may be required.

Research limitations/implications

The paper is the first part of an ongoing research agenda on the subject of heuristic‐based management and only refers to variation processes.

Originality/value

The paper links complex systems theories to evolutionary thought. It also relates principles of cybernetics to those of game theory. The proposal has been formalized based on these relations, and has been called heuristic‐based management. Principles first developed in information theory, organisational cybernetics, and evolutionary thought are used so that a complex system can be effective when interacting with a complex environment.

Details

Kybernetes, vol. 39 no. 9/10
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 1 April 2001

F. Guo, S. Choi, J.P. Lucas and K.N. Subramanian

Composite solders were prepared by mechanically dispersing 15v% of Cu or Ag particles into the eutectic Sn‐3.5Ag solder. The average sizes for the nominally spherical Cu…

Abstract

Composite solders were prepared by mechanically dispersing 15v% of Cu or Ag particles into the eutectic Sn‐3.5Ag solder. The average sizes for the nominally spherical Cu and Ag particles were 6 and 4 microns, respectively. Two different processing methods were used to prepare the composite solders: blending the powdered particles with solder paste, and adding particles to the molten solder at 2808C. The composite solders were characterised by studying the morphology, size and distribution of the reinforcing phase. Particular interest and emphasis are given towards the modifications of the reinforcements during the reflow process. Microstructural features and chemical analysis of the composite solders were studied using optical and scanning electron microscopy (SEM), and energy dispersive x‐ray (EDX) analysis. The effect of reflow and isothermal ageing on the microstructure as well as the morphological changes in the interfacial IM layer of the composite solders were extensively analysed. A mechanism for IM layer growth is proposed for solid state isothermal ageing.

Details

Soldering & Surface Mount Technology, vol. 13 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

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