Search results

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

Since 1986, there has not been another federal immigration reform policy that has legalized the status of the undocumented migrants living and working inside the United States. Instead, there has been only criminalization and punitive measures. From the administrations of Bill Clinton to Donald Trump, and now that of Joe Biden, there has been a bipartisan continuity of the “enforcement-only approach,” which has corresponded with capital's increased reliance and preference for non-citizen labor. The abandonment of inclusive citizenship and rights-based immigration reform in favor of restrictive measures allows for capitalists to increase capital accumulation through greater exploitation of migrant workers. Working backwards from this process shows how this method of labor procurement and exploitation extends from the roots of imperialist expansionism abroad: the imposition of free-trade agreements and economic displacement, regional militarization, and the regulation and criminalization of cross-border migration. Because of these factors, it has become apparent that prospects for citizenship and rights-based reform will not likely be advanced electorally within the current configuration of party politics in the United States, and has therefore shifted to different forms of class struggle in workplaces and communities across the country.

This chapter studies how entrepreneurship research has evolved at the Latin American level. Using the database available in the Web of Science Core Collection, a period-by-period bibliometric analysis is carried out to identify possible changes in research trends over time. On the one hand, the results show that in the period 2000–2006, research focuses mainly on rural development, community development and financial resources. On the other hand, in the period 2007–2013, the research priority is related to international entrepreneurship, private capital raising and studies based on the Global Entrepreneurship Monitor (GEM). Finally, during the period between 2014 and 2020, research focused mainly on self-employment, family businesses, promotion of angel investor networks, venture capital, and female entrepreneurship. The results of this study may be of interest to academics, researchers, and policymakers to understand the evolution of this topic in recent decades and to promote entrepreneurship and innovation in the region.