Wenchao Tian, Jianyuan Jia, Guiming Chen and Guangyan Chen
The “Snap back” problem of the micro‐cantilever remains one of the dominant failure mechanisms in the Micro Electro‐mechanical System (MEMS). By analyzing the Hamaker micro…
Abstract
The “Snap back” problem of the micro‐cantilever remains one of the dominant failure mechanisms in the Micro Electro‐mechanical System (MEMS). By analyzing the Hamaker micro continuum medium and solid physics principle, the consistency model of Wigner‐Seitz (W‐S) continuum medium is presented. The gap revision coefficients of the body with the face‐centered cubic structure are derived, which include the attractive force and the repulsive one. The adhesion model of the 500 µ m X 1 µ m silicon micro‐cantilever coated by Au is established. The micro‐cantilever static relationship between the elastic force and the adhesion force is discussed. The reason of the microcantilever “snap back” problem, an instable balanced point, is discovered. Increasing the rigidity of the micro‐cantilever, a method to avoid the micro‐cantilever “snap back” to happen, is put forward, which improves MEMS structure design and enhances MEMS reliability.
Details
Keywords
This paper aims to study the electric sliding wear performance of a rigid overhead line/contact strips and to find an optimal overhead line/contact strip pair to minimize the wear…
Abstract
Purpose
This paper aims to study the electric sliding wear performance of a rigid overhead line/contact strips and to find an optimal overhead line/contact strip pair to minimize the wear of the contact strip under direct current (DC) passage.
Design/methodology/approach
The tribological characteristics of an overhead line against four contact strips with DC were experimentally investigated using a block-on-disc tester. The wear and temperature of the contact strips were collected and analysed. The severe wear mechanism of the contact strips was discussed.
Findings
Using Taguchi’s method, DC was found to be the most important factor affecting the wear and temperature of current collectors, the normal force being the second and the sliding velocity the weakest. The abnormal wear of current collectors was attributed to arc ablation and poor thermal stability of collectors. The wear performances of current collectors could be optimized by matching different Cu-impregnated carbon strips with the Cu–Ag wire and the wear of current collectors could be reduced by selecting the appropriate normal force, DC and sliding velocity.
Originality/value
Among all test parameters such as the DC, normal force, sliding speed and collector type, DC was identified as the most important factor affecting the wear and temperature of contact strips for the first time. The arc ablation and thermal stability of collectors were considered to be two main factors affecting the wear of the collectors.
Details
Keywords
Orly Carvache-Franco, Glenda Gutiérrez-Candela, Paola Guim-Bustos, Mauricio Carvache-Franco and Wilmer Carvache-Franco
This paper aims to examine the relationship between research and development (R&D) intensity and innovative performance and R&D intensity as a moderating variable in the…
Abstract
Purpose
This paper aims to examine the relationship between research and development (R&D) intensity and innovative performance and R&D intensity as a moderating variable in the relationship between sources of information and innovative performance.
Design/methodology/approach
This is a quantitative, nonexperimental, cross-sectional study of the data collected from national surveys of innovation activities from Ecuador, Peru and Chile where the investigation was carried out. A bivariate probit regression was applied.
Findings
The results of the investigation pinpoint that R&D intensity is positively related to the innovation of products and processes in Ecuador and Peru. However, no relationship was found in Chile. As a moderating variable of the information sources (customers, suppliers and competitors), and the innovation of products and processes, it shows different results in the three countries examined.
Research limitations/implications
This study contributes to the literature with evidence in countries with low rates of investment in R&D in the countries examined, this relationship does not always exist; this relationship is considered to be dependent on the complexity of the knowledge and internal capabilities of the company required to achieve innovation, and this complexity could vary according to the type of manufacturing and technology level of the companies. Thus, in manufacturing companies of less complexity to achieve the necessary knowledge for innovation, low rates of investment in R&D are sufficient for the relationship to exist.
Practical implications
By increasing their R&D intensity, companies acquire technology and develop internal skills and capabilities that boost their innovative potential. Nevertheless, it is not enough to increase R&D intensity to take advantage of external sources of information, it is also necessary to boost the absorptive capacity to assimilate and take advantage of external knowledge.
Originality/value
This study contributes to the scarce evidence that exists, on the literature in developing countries, on the effect of R&D intensity on innovative performance and provides evidence of R&D intensity as a moderating variable of the relationship between sources of information and innovative performance.
Details
Keywords
Yuhan Li, Qun Luo, Shiyu Zhao, Wenyan Qi, Zhong Huang and Guiming Mei
The purpose of this paper is to study the aerodynamic characteristics and uplift force tendencies of pantographs within the operational height span of 1,600–2,980 mm, aiming to…
Abstract
Purpose
The purpose of this paper is to study the aerodynamic characteristics and uplift force tendencies of pantographs within the operational height span of 1,600–2,980 mm, aiming to offer valuable insights for research concerning the adaptability of pantograph-catenary systems on double-stack high container transportation lines.
Design/methodology/approach
Eight pantograph models were formulated based on lines with the contact wire of 6,680 mm in height. The aerodynamic calculations were carried out using the SST k-ω separated vortex model. A more improved aerodynamic uplift force method was also presented. The change rule of the aerodynamic uplift force under different working heights of the pantograph was analyzed according to the transfer coefficients of the aerodynamic forces and moments.
Findings
The results show that the absolute values of the aerodynamic forces and moments of the upper and lower frame increase with the working height, whereas those of the collector head do not change. The absolute values of the transfer coefficients of the lower frame and link arm were significantly larger than those of the upper frame. Therefore, the absolute value of the aerodynamic uplift force increased and then decreased with the working height. The maximum value occurred at a working height of 2,400 mm.
Originality/value
A new method for calculating the aerodynamic uplift force of pantographs is proposed. The specifical change rule of the aerodynamic uplift force of the pantograph on double-stack high container transportation lines was determined from the perspective of the transfer coefficients of the aerodynamic forces and moments.
Details
Keywords
Fabiane Letícia Lizarelli, Artur Yuiti Ishizaka and José Carlos de Toledo
The objectives of this study are to identify which inputs are most relevant for development and successful introduction of product and process innovations and identify the impacts…
Abstract
Purpose
The objectives of this study are to identify which inputs are most relevant for development and successful introduction of product and process innovations and identify the impacts of these two types of innovation on the performance of Brazilian manufacturing companies.
Design/methodology/approach
This study analyzes the relationships between input, output and outcome for a sample of 5,586 Brazilian manufacturing companies by using partial least squares structural equation modeling (PLS-SEM).
Findings
The results indicate that (1) product innovations are favored by internal resources, (2) process innovations are favored by external resources, (3) product innovations mainly affect a range of products offered by companies and (4) process innovations mainly affect performance in manufacturing capacity, flexibility and costs.
Practical implications
By identifying the main efforts to improve the innovation performance and input-output-outcome relationships, the results can contribute to a better decision-making process for innovation investments and management in companies as well as for policymakers. The results are particularly relevant given that the Brazilian case can serve as a reference for other emerging countries.
Originality/value
Analyses of the innovation in input-output-outcome relationships were performed in a comprehensive way by using a set of variables for defining each construct. This allowed each construct to be better measured, which improved the understanding of the relationships between inputs and outcomes mediated by product and process innovations.
Details
Keywords
Muhammad Usman Shehzad, Jianhua Zhang, Phong Ba Le, Khalid Jamil and Ziao Cao
Given the importance of frugal innovation for small and medium-sized enterprises (SME) in developing countries, this study aims to explore the role of IT resources on frugal…
Abstract
Purpose
Given the importance of frugal innovation for small and medium-sized enterprises (SME) in developing countries, this study aims to explore the role of IT resources on frugal innovation through the mediating roles of knowledge sources and to what extent the relationship between sources of knowledge and frugal innovation is strengthened or weakened under the moderating effects of market turbulence.
Design/methodology/approach
This is an empirical study. Data were gathered from 355 SME employees of Pakistan through a questionnaire survey; the variance-based PLS-SEM approach was used to analyze the data.
Findings
Findings reveal the significant impacts of IT resources on different aspects of frugal innovation, namely, frugal functionality (FF), frugal cost (FC) and frugal ecosystem (FE). Moreover, the paper highlights the mediating roles of sources of knowledge in the relationship between IT resources and frugal innovation in frugal functionality and frugal cost. Findings also revealed that the moderation of market turbulence strengthens the effects of sources of knowledge on frugal functionality and ecosystem, but surprisingly weakens the relationship between sources of knowledge and frugal cost.
Research limitations/implications
To bring a deeper understanding of the significant role of IT and knowledge sources, future research should examine the potential moderating role of environmental factors or perceived organizational support or mediating role of knowledge management processes in the relationship between IT resources and frugal innovation.
Practical implications
The paper provides a valuable understanding and novel approach for directors of SMEs in developing countries to improve their frugal innovation capability through IT and knowledge resources.
Originality/value
This study contributes to bridging research gaps in the literature and advances how IT resources, directly and indirectly, help firms improve frugal innovation capability via mediating roles of sources of knowledge.
Details
Keywords
Shoaib Abdul Basit, Thomas Kuhn and Uwe Cantner
Knowledge competencies and (R&D) activities are one of the most important sources of innovation and have been widely discussed in the literature. In comparison, the role of the…
Abstract
Purpose
Knowledge competencies and (R&D) activities are one of the most important sources of innovation and have been widely discussed in the literature. In comparison, the role of the competitive environment for the innovation activities of firms is still open to debate and has not been fully understood yet. Therefore, this paper intends to provide new evidence on the interaction between knowledge competencies and R&D activities of firms on the one side and their competitiveness in the market environment on the other. In particular, the moderating function of market competition is explored. In this respect, the analysis covers the main innovation types as well as both sectors, manufacturing and services.
Design/methodology/approach
The empirical analysis is based on a three years panel dataset of German manufacturing and service firms obtained from Mannheim Innovation Panel (MIP) and Community Innovation Surveys (CISs: 2011, 2013 and 2015). For the estimation, a binary instrumental variable treatment model with Heckman selection method is used. Also, it provides a suitable approach to estimating the binary variables in order to cope with endogeneity concerns.
Findings
The estimation results show that R&D activities and knowledge competencies are positively related to innovation activities of different types conditioned on firms' specific perception of their competitive environment, in terms of outdated products/services as well as strong competition from abroad. Most importantly, the results from the moderation estimation reveal that there is a significant difference between the manufacturing and service sector. Service firms engage more in internal R&D activities on generating product innovations while the manufacturing firms conduct more external R&D on specific types of innovation. Further, the authors find that strong competition from abroad positively and significantly reinforces the effect of knowledge competencies on innovation activities for more types in services than in manufacturing. In contrast, outdated products and services tend to decline the effect of knowledge competencies for some innovation types in both sectors. The authors also observe a positive and significant reinforcement effect on knowledge competencies. However, it is found more beneficial for service firms since they can employ more innovation strategies.
Originality/value
The focus of the study is mainly on the impact of firms' competitive environment on innovation activities in various types through its interaction with knowledge competencies and R&D activities, across manufacturing and service firms.
Details
Keywords
Hazard warning schemes provide efficient hazard recognition and promote project safety. Nevertheless, these schemes perform poorly because the warning information is calibrated…
Abstract
Purpose
Hazard warning schemes provide efficient hazard recognition and promote project safety. Nevertheless, these schemes perform poorly because the warning information is calibrated for individual characters and is not prioritized for the entire system. This study proposes a hazard warning scheme that prioritizes hazard characters from the inspection process based on the inspectors' experience.
Design/methodology/approach
First, hazard descriptions were decomposed into their characters, forming a double-layer network. Second, warning schemes based on cascading effects were proposed. Third, character-based warning schemes were simulated for various experiences.
Findings
The results show that when a specific hazard is detected, the degree centrality is the most effective parameter for prioritization, and hazard characters should be prioritized based on betweenness centrality for experienced inspectors, whereas degree centrality is preferred for novice inspectors.
Originality/value
The warning scheme theoretically supplements the information-processing theory in construction hazard warnings and provides a practical warning scheme with priority for the development of automated hazard navigation systems.
Details
Keywords
Dave Towey, James Walker and Ricky Ng
Embracing reflective practice and retrospection, with a goal of identifying commonalities, this paper aims to examine delivery of engineering subjects in both traditional higher…
Abstract
Purpose
Embracing reflective practice and retrospection, with a goal of identifying commonalities, this paper aims to examine delivery of engineering subjects in both traditional higher education (THE) and technical and vocational education and training (TVET).
Design/methodology/approach
Reflections on actions and autoethnography were used to examine the teaching and learning experiences of three educators across two higher education (HE) institutions (HEIs) in the greater Chinese context. Literature reviews and historical contexts are outlined to support the approaches and insights identified.
Findings
This paper presents a number of common characteristics and challenges identified across both THE and TVET. Drawing on the successful embrace of ambiguity and change in recent software engineering (SE) development paradigms, recommendations are made for how the agile SE themes can be applied in a larger sense to address the wider challenges facing both THE and TVET.
Originality/value
To the best of the authors’ knowledge, this is the first time that engineering education has been examined and contrasted in the contexts of THE and TVET. The similarities and common challenges may represent a new focus for related work, and the presented insights, from agile methodologies in SE, represent a new perspective for viewing future HE and TVET sustainability.