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1 – 10 of 44Abstract
Thick film superconductors with the nominal composition Bi2Pb0.5Sr2Ca2.5Cu3.5Ox were fired on stainless steel substrates and on alumina substrates covered with silver or gold thick film conductors. Films on stainless steel substrates were semiconducting due to reaction between the superconducting film and oxidised chromium and iron from the steel. Tc(R=0) of films on silver was between 80 K and 90 K while Tc (R=0) on gold was below 60 K. The low Tc (R=0) of films on gold is attributed to the interaction between the gold layer and copper from the superconductor.
Abstract
Interactions between stainless steel and silver and gold based thick film conductors and YBa2Cu3O7 thick film superconductors were studied by SEM and EDX. The stainless steel reacted with the superconducting layer, forming a Ba‐Fe‐O compound on the interface, while BaO‐depleted YBa2Cu3O7 compound transformed into insulating Y2BaCuO5 compound. When YBa2Cu3O7 is fired on a gold thick film conductor, a thin layer of Y2BaCuO5 compound forms between the conductor and the superconducting film. In the case of a thin Ag conductor, BaO diffused through the silver film and reacted with alumina ceramic to the depth of a few μm. When a thicker silver layer (40–50 μm) was used, diffusion did not occur.
M. Hrovat, S. Bernik, D. Kolar and I. Jarkovi?
A superconducting material with a composition Y1−xBa2Cu3O7−3/2x − x/2 Bi2O3 (x = 0·1 and 0·2) was synthesised. The influence of Bi2O3 additions on sintering was studied…
Abstract
A superconducting material with a composition Y1−xBa2Cu3O7−3/2x − x/2 Bi2O3 (x = 0·1 and 0·2) was synthesised. The influence of Bi2O3 additions on sintering was studied. Preliminary investigations of the Bi‐Sr‐Ca‐Cu‐O system were also made. Thick film pastes, prepared from Y1−xBixBa2Cu3O7 compositions, from the compound YBa2Cu3O7 with 10 w/o addition of Bi2CuO4 and from two compositions in the Bi‐Sr‐Ca‐Cu‐0 system, were fired on Al2O3 and ZrO2 substrates. All thick film materials based on YBa2Cu3O7 compound were superconducting at temperatures above 77 K when fired on ZrO2 substrates, while only a material with the starting composition Y0·8Ba2Cu3O6.7 − 0·1 Bi2O3 reached zero resistivity above 77 K on Al2O3 substrates. Tc (onset) of samples based on the YBa2Cu3O7 compound was around 95 K, and of samples from the Bi‐Sr‐Ca‐Cu‐O system between 95 and 100 K.
Abstract
A superconducting material with the composition YBa1.8Pb0.2Cu3O7 was synthesised. The influence of PbO addition on the sintering and formation of the superconducting compound YBa2Cu3O7 was investigated. A thick film paste, prepared from prereacted material and an organic vehicle, was fired on Al2O3 and ZrO2 substrates. The resistivity of samples on ZrO2 substrates decreased to zero around 90 K, while samples on Al2O3 substrates did not reach zero resistivity until 77 K, which is probably due to the differences in thermal expansion coefficient between Al2O3 and the superconducting material. Interactions between Pt alloy based thick film conductors and superconducting material were studied.
Tensie Steijvers, Nadine Lybaert and Julie Dekker
The importance of formal human resource (HR) practices is widely recognized in management literature, but under-researched in the small business and family firm domain. Previous…
Abstract
Purpose
The importance of formal human resource (HR) practices is widely recognized in management literature, but under-researched in the small business and family firm domain. Previous research indicates that family firms rely more on informal HR practices, based on social networks. However, given the heterogeneity of family firms, one cannot assume that all family firms are reluctant to formalize their HR. As the CEO is the key decision maker who covers HR management in family firms, the effect of the CEO type on formal HR practices will be studied. The paper aims to discuss these issues.
Design/methodology/approach
Based on a large-scale survey, resulting in a response of 532 family SMEs, the authors perform a hierarchical regression analysis studying the effect of a family/nonfamily CEO on the use of formal HR practices, introducing several moderating effects: CEO generational stage, tenure and education.
Findings
Results indicate that family firms with a family CEO have more formal HR practices than those managed by a nonfamily CEO due to higher levels of goal alignment and intentional trust between the owning family and family CEO. Moreover, family firms managed by first generation family CEOs and family CEOs with a higher education have more formal HR practices.
Practical implications
The findings suggest that family CEOs can be equally or even more able as nonfamily CEOs to run a family firm in a formalized/professionalized manner.
Originality/value
Given the scant amount of research on HR formalization in family firms, even though literature documents performance increasing effects, this study fulfils the need to study the effect of the CEO on HR formalization.
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Ming Jiang, Mengyang Shi, Jiamao Li, Juan Liu, Lei Zhang, Jian Qin, Yongtao Jiu, Bin Tang and Dong Xu
This paper aims to study the effects of MnO2 on the ZnO–Bi2O3-based varistor prepared via flash sintering (FS)
Abstract
Purpose
This paper aims to study the effects of MnO2 on the ZnO–Bi2O3-based varistor prepared via flash sintering (FS)
Design/methodology/approach
MnO2-doped ZnO–Bi2O3-based varistors were successfully prepared by the FS with a step-wise increase of the .current in 60 s at the furnace temperature <750°C under the direct current electric field of 300 V cm−1. The FS process, microstructure and the electrical performance of ZnO–Bi2O3-based varistors were systematically investigated.
Findings
The doping of MnO2 significantly decreased the onset temperature of FS and improved the electrical performance of FS ZnO varistor ceramic. The sample with 0.5 mol% MnO2 doping shows the highest improvement, with the nonlinear coefficient of 18, the leakage current of 16.82 µA, the threshold voltage of 459 V/mm and the dielectric constant of 1,221 at 1 kHz.
Originality/value
FS is a wonderful technology to enhance ZnO varistors for its low energy consumption, and a short sintering time can reduce grain growth and inhabit Bi2O3 volatilize, yet few research studies work on that. In this research, the authors analyzed the FS process and improved the electrical characteristics through MnO2 doping.
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The purpose of this paper was to develop the methodology of thick-film/low temperature co-fired ceramic (LTCC) multilayer thermoelectric microgenerator fabrication including the…
Abstract
Purpose
The purpose of this paper was to develop the methodology of thick-film/low temperature co-fired ceramic (LTCC) multilayer thermoelectric microgenerator fabrication including the procedure of silver-nickel thermocouples integration with LTCC.
Design/methodology/approach
To miniaturize the structures and to increase the output parameters (generated voltage, electrical power), the microgenerator was designed as multilayer systems. It allows to reduce size of the system and to increase the number of thermocouples integrated inside the structure. It also protects buried thermocouples against exposure to harmful external factors (e.g. moisture, oxidation and mechanical exposures). As a substrate, LTCC was used. For the thermocouples fabrication, thick-film pastes based on silver and nickel were chosen. Ag/Ni thermocouple has nearly three times higher Seebeck coefficient and 30 per cent lower electrical resistance than the combination of Ag/PdAg used in previous works of the author.
Findings
A multi-layer thick-film thermoelectric generator based on LTCC and Ag, Ni pastes was fabricated. Thirty Ag/Ni thermocouples were precisely screen-printed on few layers. Thermocouples’ arms are 15 mm long and about 150 μm wide. Interlayer connections (via-holes filled with conductive paste) provided the electrical contact between the layers. The biggest fabricated harvester consisted of 90 miniature thermocouples buried inside the LTCC.
Originality/value
The paper presents the results of research that provided to optimize the co-firing process of the LTCC/Ni set. In the result, the methodology of co-firing of silver-nickel thermocouples and LTCC ceramic was elaborated. Also, the methodology of fabrication of miniature thermoelectric energy harvesters was optimized.
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Ascarya Ascarya and Atika Rukminastiti Masrifah
This study aims to devise policies in implementing cash waqf system of Baitul Maal wat Tamwil (BMT) in Indonesia, enabling the BMT to optimize its commercial and social activities…
Abstract
Purpose
This study aims to devise policies in implementing cash waqf system of Baitul Maal wat Tamwil (BMT) in Indonesia, enabling the BMT to optimize its commercial and social activities to better achieve outreach, sustainability and welfare impact.
Design/methodology/approach
This study uses the strategic assumption surfacing and testing (SAST) method, with three groups of knowledgeable respondents, including expert, BMT practitioner and regulator to formulate important and certain policies.
Findings
The results show that four types of policies are required to improve cash waqf system of BMT, including 12 internal strategic policies, 15 internal operational policies, 15 external strategic policies and 9 external operational policies, which were found to be within a “certain planning region.” All of these policies have been agreed significantly by each group of respondents, as well as by all respondents combined. The most important-certain policies include Shiddiq, Amanah and professional Nazir, inculcate Islamic values to BMT employees and members, standard operating procedure and standard operating management of cash waqf management, technical assistance for Nazir to manage cash waqf and IT systems for BMT-cash waqf administration.
Research limitations/implications
The qualitative method used has its limitations, which could be improved by incorporating other methods. Moreover, the case and respondents are all Indonesian, so that the results are possibly only applicable to BMTs in Indonesia.
Practical implications
BMTs could adopt these policies in implementing their cash waqf management optimally.
Social implications
The management of cash waqf by BMT could help improve the social activities of the Baitul Maal directly from social cash waqf and indirectly from productive cash waqf.
Originality/value
To the best of the authors’ knowledge, this is the first study using SAST method to determine policies needed by the BMT to upgrade its cash waqf management producing more social programs for the society.
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Shard, Devesh Kumar and Sapna Koul
This study aims to gain insights into how students perceive online examination practices and evaluation, as well as identify the key factors that impact their intentions toward…
Abstract
Purpose
This study aims to gain insights into how students perceive online examination practices and evaluation, as well as identify the key factors that impact their intentions toward online exams.
Design/methodology/approach
This empirical study conducted in India utilized an online survey method between May 24 and June 14, 2022. The data were collected from 712 undergraduate and postgraduate students through a Google Docs questionnaire. Descriptive analysis, exploratory factor analysis (EFA), regression and reliability analysis were conducted to analyze the data.
Findings
There are many studies related to the adoption of online learning. However, there are limited studies that explore the adoption and acceptance of online examinations and evaluations. This paper intends to fill this gap and tries to highlight important factors influencing online examination usage by the students. Five important factors emerged in the study include “pedagogy, validity, reliability,” “practicality,” “security,” “facilitating condition” and “intention,” The study concludes that taking tests online is preferred for several reasons, including the perceived increased dependability of grades and the decreased cost, time and effort associated with taking exams.
Research limitations/implications
This research explores students' perceptions of learning management systems (LMS)-based online exams and provides insights for students to better prepare and adapt. It assists policymakers in developing fair assessment policies and improving LMS platforms. The study contributes to the theoretical understanding of e-learning and calls for further research to enhance the effectiveness of online exams. It identifies gaps in existing literature and recommends larger sample sizes, broader representation, longitudinal data collection and conversational methods for future research.
Originality/value
This study shows increasing research on e-learning and online examinations, mostly using quantitative methods. The important variables for understanding students' perceptions of online exams are “pedagogy, validity, reliability,” “practicality,” “security,” “facilitating condition” and “intention.” Concerns raised include validity, fairness and security. Electronic exams are more suitable for formative evaluation, and validity, reliability, security and adaptability are key pillars for successful online testing.
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The purpose of this paper is to rank the users’ attitude on major components of mobile cloud computing (MCC) security and investigate the degree of impact of these components on…
Abstract
Purpose
The purpose of this paper is to rank the users’ attitude on major components of mobile cloud computing (MCC) security and investigate the degree of impact of these components on MCC security as a whole.
Design/methodology/approach
Hypotheses were evolved and tested by data collected through an online survey-questionnaire. The survey was administered to 363 users from Chinese organizations. Statistical analysis was carried out and structural equation model was built to validate the interactions.
Findings
The eight components of MCC security in the order of importance are as follows: mobile device related, user identity related, deployment model related, application-level security issues, data related, virtualization related, network related and service delivery related. The empirical analysis validates that these security issues are having significant impact on perceived security of MCC.
Practical implications
Constant vigilance on these eight issues and improving the level of user awareness on these issues enhance the overall security.
Social implications
These issues can be used for designing and developing secured MCC system.
Originality/value
While several previous research has studied various security factors in the MCC security domain, a consolidated understanding on the different components of MCC security is missing. This empirical research has identified and ranked the major components of MCC security. The degree of impact of each of these components on overall MCC security is identified. This provides a different perspective for managing MCC security by explaining what components are most important.
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