Marika Immonen, Jinhua Wu, Hui Juan Yan, Peifeng Chen, Jian Xiong Xu and Tarja Rapala‐Virtanen
The purpose of this paper is to study fabrication of optical‐PCBs on panel scale boards in a conventional modern PCB process environment. It evaluates impacts on board design and…
Abstract
Purpose
The purpose of this paper is to study fabrication of optical‐PCBs on panel scale boards in a conventional modern PCB process environment. It evaluates impacts on board design and manufacturing with the developed optical board verifiers outlining challenges and requirements for manufacturing low‐loss waveguide structures and optical building blocks. The study aims to expand the current knowledge in the field by adding results obtained by utilizing industrial production infrastructure and developed scalable manufacturing processes to fabricate optical‐PCBs and board assemblies in high‐volumes and low‐cost manner.
Design/methodology/approach
Impacts on board design and manufacturing were studied with the developed optical technology verifiers. One verifier is optical‐PCB with embedded waveguides, integrated i/o couplers and optical vias. Another verifier is large size PCB with optical layer. A system‐level optical board assembly with 12.5 Gb/s Tx/Rx devices on surface mounted ball grid array (BGA) modules is designed for optical link analysis. Fabricated optical structures on verifiers are evaluated of their physical characteristics utilizing optical, SEM, LSCM analysis methods. Performance testing is conducted using standard optical transmission measurement methods and equipment.
Findings
The paper provides empirical results about fabrication of multimode optical waveguides with conventional PCB process equipment. Results suggest that current coating and imaging equipments are capable of producing optical waveguide patterns with high resolution and size accuracy. However, fabricators would require larger process window and defect tolerance for processing optical materials to obtain low‐loss waveguides with sufficient yields.
Research limitations/implications
Because of the limited amount of design variants in production verifiers evaluated in this paper, some impacts like effect of base material, board construction, optical layer location and beam coupling solution were not evaluated. Likewise, impacts on long‐term stability and cost were not addressed. These factors however require further investigation to address technical feasibility of optical PCBs technology prior commercial high volume production.
Practical implications
The paper includes implications for the development of a fabrication methods and testing procedures for optical polymer waveguide layers on PCBs.
Originality/value
This paper fulfils need to provide results on design, fabrication and characterization of optical PCBs and backplanes from industrial fabricator's perspective. The paper provides input for end‐user and developers to evaluate technical performance, robustness, and maturity of building blocks and supply chain to support polymer waveguide based technology for intra‐system optical links.
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Li-Ping Guo, Li-Juan Chai, Yan-Hui Xu, Cong Ding and Yuan-Zhang Cao
High-ductility cementitious composites (HDCC) have an excellent crack controlled capacity and corrosion resistance capacity, which has a promising application in structure…
Abstract
Purpose
High-ductility cementitious composites (HDCC) have an excellent crack controlled capacity and corrosion resistance capacity, which has a promising application in structure engineering under harsh environment. The purpose of this study is to explore the corrosion mechanism of steel bar in HDCC.
Design/methodology/approach
Intact and the pre-cracked HDCC specimens under the coupled action of different dry–wet cycles and chloride attack were designed, and intact normal concrete (NC) was also considered for comparison. Corrosion behavior of a steel bar embedded in HDCC was analyzed by an electrochemical method, a chloride permeability test and X-ray computed tomography.
Findings
Steel corrosion probability is related to the chloride permeability of the HDCC cover, and the chloride permeability resistance of HDCC is better than that of NC. Besides, crack is the key factor affecting the corrosion of steel bars, and the HDCC with narrower cracks have a lower corrosion rate. Slight pitting occurs at the crack tips. In addition, the self-healing products and corrosion products fill up the cracks in HDCC, preventing the external aggressive ions from entering and thereby decreasing the steel corrosion rate.
Originality/value
HDCC has a superior corrosion resistance than that of NC, effects of variable crack width on corrosion behavior of steel bar in HDCC under the coupled actions of different dry–wet cycles and chloride attack are investigated, which can provide the guide for the design application of HDCC material in structure engineering exposed to marine environment.
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Xiaojie Xu and Yun Zhang
The Chinese housing market has gone through rapid growth during the past decade, and house price forecasting has evolved to be a significant issue that draws enormous attention…
Abstract
Purpose
The Chinese housing market has gone through rapid growth during the past decade, and house price forecasting has evolved to be a significant issue that draws enormous attention from investors, policy makers and researchers. This study investigates neural networks for composite property price index forecasting from ten major Chinese cities for the period of July 2005–April 2021.
Design/methodology/approach
The goal is to build simple and accurate neural network models that contribute to pure technical forecasts of composite property prices. To facilitate the analysis, the authors consider different model settings across algorithms, delays, hidden neurons and data spitting ratios.
Findings
The authors arrive at a pretty simple neural network with six delays and three hidden neurons, which generates rather stable performance of average relative root mean square errors across the ten cities below 1% for the training, validation and testing phases.
Originality/value
Results here could be utilized on a standalone basis or combined with fundamental forecasts to help form perspectives of composite property price trends and conduct policy analysis.
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Tinggui Chen and Hui Wang
The purpose of this paper is to investigate consumers' purchase intention of wild freshwater fish. Facing the endangering ecology in the Yangtze River Basin, the Chinese…
Abstract
Purpose
The purpose of this paper is to investigate consumers' purchase intention of wild freshwater fish. Facing the endangering ecology in the Yangtze River Basin, the Chinese government has implemented a ten-year fishing ban policy to protect the wild freshwater fishery resources from 2020. In this context, such questions are raised as how do consumers react to this and are they willing to reduce or even refuse to purchase wild freshwater fish to protect the aquatic biological resources in the Yangtze River Basin?
Design/methodology/approach
A total of 1,235 consumers from eight provinces (including two province-level municipalities) in the Yangtze River Basin filled out the online questionnaires. The data (n = 1,096) are analyzed by structural equation model (SEM) to verify the relationships between the variables.
Findings
The results show that subjective norm is the strongest direct determinant of purchase intention, followed by personal norm, attitude, environmental concern and perceived behavioral control. It is also found that attitude, subjective norm, perceived behavioral control and environmental concern have significant effects on personal norm which plays a significant mediating role in forming purchase intention. On this basis, specific policy recommendations are proposed.
Originality/value
This paper investigates consumers' purchase intention from the perspective of ecological protection and obtains a more comprehensive explanation of the purchase intention by combining the theory of planned behavior (TPB) and theory of norm activation.
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This chapter uses the entrepreneurial experiences of women entrepreneurs in urban China as an empirical case to discuss contextual influences on women's everyday entrepreneurial…
Abstract
This chapter uses the entrepreneurial experiences of women entrepreneurs in urban China as an empirical case to discuss contextual influences on women's everyday entrepreneurial experience in developing countries. Based on thematic analysis of women's own accounts of their entrepreneurial experiences, four contextual influences emerged: (1) preentrepreneurial work experience, (2) national entrepreneurial development, (3) cultural values, and (4) gendered work ideology. These influences shaped and were shaped by women's entrepreneurial identities, decisions, and actions in situated contexts. To further understand women's negotiations with these influences in developing countries, future research are called for to investigate how women resist dominant structures to carve out entrepreneurial agencies and enact resiliency to build sustainable businesses.