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This paper aims to demonstrate low-temperature bonding for piezoelectric materials at temperatures well below the relevant Curie temperatures so as to avoid depolarization…
This paper aims to demonstrate low-temperature bonding for piezoelectric materials at temperatures well below the relevant Curie temperatures so as to avoid depolarization of the piezoelectric material during bonding.
Au-coated test samples of lead zirconate titanate (PZT) are bonded to a WC-based resonant backing layer with In–Bi eutectic material in which the In–Bi metal system is a preform or thin, evaporated layers. The bonded samples are characterized using electrical impedance spectroscopy and cross-section microscopy. The first technique verifies the integrity of polarization and reveals the quality of the bondline in a non-destructive manner, particularly looking for voids and delaminations. The latter technique is destructive but gives more precise information and an overview of the structure.
Successful low-temperature (115°C) bonding with intact PZT polarization was demonstrated. The bondlines show a layered structure of Au/Au–In intermetallic compounds (with Bi inclusions)/Au, capable of withstanding temperatures as high as 271°C before remelting occurs. For bonded samples using In–Bi preform, repeatable bonds of high quality (very little voiding) were obtained, but the bonding time is long (1 h or more). For bonded samples using evaporated thin films of In–Bi, bonding can be performed in 30 min, but the process needs further optimization to be repeatable.
Low-temperature solid-liquid interdiffusion (SLID) bonding is a novel technique, merging the fields of low-temperature solder bonding with the SLID/transient liquid phase (TLP) approach, which is normally used for much higher temperatures.
By using a technology acceptance model (TAM) on survey results collected from two member schools of a Vietnamese educational institution, this study aims to uncover the…
By using a technology acceptance model (TAM) on survey results collected from two member schools of a Vietnamese educational institution, this study aims to uncover the key factors that affect students’ acceptance of e-learning during the Covid-19 period.
A bilingual questionnaire in English and Vietnamese was delivered. It was pre-tested on 30 participants before it was finalized. The authors first reviewed the measurement model and made adjustments to the theoretical TAM model. Then the adjusted TAM was used to investigate the relationships of the constructs in the model.
The results of the structural model show that computer self-efficacy (CSE) has a positive impact on perceived ease of use (PEOU). There is also a positive relationship between system interactivity (SI) and PEOU. Surprisingly, the authors documented that PEOU has no significant impact on students’ attitudes (ATT). The results show that SI can moderately affect ATT. Finally, it is noted that the social factor (SF) directly affects the student’s attitudes (ATT).
This study contains three limitations. First, as this study only focuses on undergraduate programs, readers should be careful in applying the findings and/or implications of this study to other education levels such as K-12, vocational training and postgraduate programs. Second, the findings are generated within the context of one type of e-learning, conducted via Google Meet. Therefore, future research is needed to provide further validation and comparison across other forms of e-learning. Finally, to further prevent the common bias problem, future research should use both five-point and seven-point Likert scales for the response options in the survey, as well as use negatively worded items. This will help prevent respondents from providing similar answers to all questions.
This study has both theoretical and practical implications. From a theoretical perspective, the study can provide a solid framework for similar studies. From a practical perspective, this study offers implications for governments and universities in the process of adopting e-learning, given that the Covid-19 pandemic is currently in its second and more dangerous wave.
This study aims to explore the suitability and challenges of implementing fair value accounting (FVA) in Vietnam, an emerging/transitioning economy. While such…
This study aims to explore the suitability and challenges of implementing fair value accounting (FVA) in Vietnam, an emerging/transitioning economy. While such implementation would enable convergence with International Financial Reporting Standards, standard setters and auditors have raised practical concerns about its adoption.
This qualitative study uses semi-structured interviews with regulators and auditors, together with an analysis of two fraud cases that illustrate the business environment in Vietnam. Public, private and capture theories guide the analysis.
The business and institutional environment in Vietnam creates several impediments to FVA being effectively implemented and transparently applied. Given the major challenges identified regarding the infrastructure necessary for this valuation system, the premature adoption of FVA may become a catalyst for corporate misconduct.
The findings are derived from data aggregated from two fraud cases and interviews, and as such, the results may not be generalisable to other settings. However, these findings may inform future research, particularly after the Ministry of Finance provides further guidance on the use of FVA in Vietnam.
A timely and critical examination of the challenges of implementing FVA in a transitioning economy is provided, and the two fraud cases reveal the complexities of the business environment in Vietnam.
This research gives voice to the tensions that developing countries are confronting as they seek to balance external pressures with internal constraints. The introduction of an assemblage of three theoretical lenses enables insights into contemporary issues associated with applying FVA in such settings.