Chengpeng Zhang, Zhihua Yu, Jimin Shi, Yu Li, Wenqiang Xu, Zheyi Guo, Hongshi Zhang, Zhongyuan Zhu and Sheng Qiang
Hexahedral meshing is one of the most important steps in performing an accurate simulation using the finite element analysis (FEA). However, the current hexahedral meshing method…
Abstract
Purpose
Hexahedral meshing is one of the most important steps in performing an accurate simulation using the finite element analysis (FEA). However, the current hexahedral meshing method in the industry is a nonautomatic and inefficient method, i.e. manually decomposing the model into suitable blocks and obtaining the hexahedral mesh from these blocks by mapping or sweeping algorithms. The purpose of this paper is to propose an almost automatic decomposition algorithm based on the 3D frame field and model features to replace the traditional time-consuming and laborious manual decomposition method.
Design/methodology/approach
The proposed algorithm is based on the 3D frame field and features, where features are used to construct feature-cutting surfaces and the 3D frame field is used to construct singular-cutting surfaces. The feature-cutting surfaces constructed from concave features first reduce the complexity of the model and decompose it into some coarse blocks. Then, an improved 3D frame field algorithm is performed on these coarse blocks to extract the singular structure and construct singular-cutting surfaces to further decompose the coarse blocks. In most modeling examples, the proposed algorithm uses both types of cutting surfaces to decompose models fully automatically. In a few examples with special requirements for hexahedral meshes, the algorithm requires manual input of some user-defined cutting surfaces and constructs different singular-cutting surfaces to ensure the effectiveness of the decomposition.
Findings
Benefiting from the feature decomposition and the 3D frame field algorithm, the output blocks of the proposed algorithm have no inner singular structure and are suitable for the mapping or sweeping algorithm. The introduction of internal constraints makes 3D frame field generation more robust in this paper, and it can automatically correct some invalid 3–5 singular structures. In a few examples with special requirements, the proposed algorithm successfully generates valid blocks even though the singular structure of the model is modified by user-defined cutting surfaces.
Originality/value
The proposed algorithm takes the advantage of feature decomposition and the 3D frame field to generate suitable blocks for a mapping or sweeping algorithm, which saves a lot of simulation time and requires less experience. The user-defined cutting surfaces enable the creation of special hexahedral meshes, which was difficult with previous algorithms. An improved 3D frame field generation method is proposed to correct some invalid singular structures and improve the robustness of the previous methods.
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Chengpeng Wan, Jiale Tao, Zaili Yang and Di Zhang
Since the start of the current century, the world at large has experienced uncertainties as a result of climate change, terrorism threats and increasing economic upheaval. These…
Abstract
Purpose
Since the start of the current century, the world at large has experienced uncertainties as a result of climate change, terrorism threats and increasing economic upheaval. These uncertainties create non-classical risks for global seaborne container trade and liner shipping networks (LSNs). The purpose of this paper is to establish a novel risk-based resilience framework to measure the effectiveness of different recovery strategies for the disruptions in LSNs in a quantitative manner.
Design/methodology/approach
Based on a resilience loss triangle model, an indicator of resilience–cost ratio is designed to measure the performance of LSNs during recovery. Four recovery strategies are proposed to test the rationality and feasibility of the developed indicator in aiding decision-making of LSNs from a resilience perspective.
Findings
The analysis results reveal that the superiorities of different recovery strategies vary depending on both the structures of LSNs and the specific requirements during recovery. Moreover, optimizing the sequence of ports being recovered will improve the overall recovery efficiency of the investigated LSN.
Research limitations/implications
As an exploratory research trying to enrich the risk-based resilience evaluation of LSNs from a complex network perspective, only two attributes (e.g. port scare and economy) are considered at the current stage when estimating the time needed to fully recover the whole LSN. In future research, more attributes from the industry may be identified and incorporated into the proposed model to further extend its ability and application scopes.
Practical implications
The findings will help to improve managerial understandings of recovery strategies to build more resilient LSNs. The proposed model has the capability to be tailored to tackle different types of risks in addition to the storm disaster condition.
Originality/value
The risk-based resilience framework and the resilience–cost ratio indicator are newly developed in this research. They can consider LSNs' structural resilience and the total costs that a recovery strategy needs to restore the whole system simultaneously.
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Multiple sequence alignment (MSA) is one of essential bioinformatics methods for decoding cis‐regulatory elements in gene regulation, predicting structure and function of proteins…
Abstract
Purpose
Multiple sequence alignment (MSA) is one of essential bioinformatics methods for decoding cis‐regulatory elements in gene regulation, predicting structure and function of proteins and RNAs, reconstructing phylogenetic tree, and other common tasks in biomolecular sequence analysis. The purpose of this paper is to describe briefly the basic concepts and formulations of gapped MSA and un‐gapped motif discovery approaches, and then review computational intelligence (CI) applications in MSA and motif‐finding problems.
Design/methodology/approach
This paper performs exhaustive literature review on the MSA and motif discovery using CI techniques.
Findings
Although CI‐based MSA algorithms were developed nearly a decade ago, most recent CI effort seems attempted to tackle the NP‐complete motif discovery problem. Applications of various CI techniques to solve motif discovery problem, including neural networks, self‐organizing map, genetic algorithms, swarm intelligence and combinations thereof, are surveyed. Finally, the paper concludes with discussion and perspective.
Practical implications
The algorithms and software discussed in this paper can be used to align DNA, RNA and protein sequences, discover motifs, predict functions and structures of protein and RNA sequences, and estimate phylogenetic tree.
Originality/value
The paper contributes to the first comprehensive survey of CI techniques that are applied to MSA and motif discovery.
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Peng Cai, Chengpeng Xu, Fei Zheng, Jingfu Song and Gai Zhao
The purpose of this paper is to investigate the effect of lanthana (La2O3) on the mechanical and tribological properties of polyimide (PI).
Abstract
Purpose
The purpose of this paper is to investigate the effect of lanthana (La2O3) on the mechanical and tribological properties of polyimide (PI).
Design/methodology/approach
The mechanical and tribological properties of PI nanocomposites filled with La2O3 were studied by molecular dynamic simulations to explore the deep mechanisms from an atomic or molecular view.
Findings
The results showed that the hardness of the PI matrix increased after La2O3 modification with a decrease of 72.4% nanoindentation depth. Besides, the friction coefficient of PI decreased by 72.2% after filling La2O3, and the shear deformation was largely reduced under the same conditions. The adsorption effect of La2O3 on the PI molecular, which reduced the atomic relative concentration, velocity, interaction with counterpart Fe layer and the temperature rise in the frictional interface, contributed to the improvement of the mechanical and tribological performance.
Originality/value
This study reveals the friction and wear mechanism of PI composites filled with rare earth oxide at the nanoscale.
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David Kimera and Fillemon Nduvu Nangolo
The purpose of this paper is to review maintenance practices, tools and parameters for marine mechanical systems that can be classified as plant, machinery and equipment (PME). It…
Abstract
Purpose
The purpose of this paper is to review maintenance practices, tools and parameters for marine mechanical systems that can be classified as plant, machinery and equipment (PME). It provides an insight for the maintenance crew on which maintenance parameters and practices are critical for a given PME systems.
Design/methodology/approach
The review paper characterizes the various maintenance parameters and maintenance practices used onshore and offshore for PME and identifies the possible gaps.
Findings
A variety of maintenance techniques are being used in the marine industry such as corrective maintenance, preventive maintenance and condition-based maintenance. As marine vehicles (MV) get older, the most important maintenance parameters become maintenance costs, reliability and safety. Maintenance models that have been developed in line with marine mechanical systems have been validated using a single system, whose outcome could be different if another PME system is used for validation.
Research limitations/implications
There is a limited literature on MV maintenance parameters and maintenance characterization regarding mechanical systems. The maintenance practices or strategies of marine mechanical systems should be based on maintenance parameters that suit the marine industry for a given PME.
Originality/value
Based on the available literature, the paper provides a variety of maintenance framework, parameters and practices for marine mechanical systems. The paper further gives an insight on what maintenance parameters, strategies and platforms are given preference in the shipping industry.
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Babajide Oyewo, Venancio Tauringana and Udechukwu Ojiako
This study aims to investigate the corporate governance (CG) determinants of sustainable manufacturing practice using zero-defect manufacturing (ZDM) from the stakeholder theory…
Abstract
Purpose
This study aims to investigate the corporate governance (CG) determinants of sustainable manufacturing practice using zero-defect manufacturing (ZDM) from the stakeholder theory and legitimacy theory perspectives.
Design/methodology/approach
Using a panel research design, the study analyses empirical data from Global 500 companies covering a 15-year period.
Findings
The results show that Board Independence, Meeting Attendance by Board Members, Board Gender Diversity and Board Skills on Sustainable Manufacturing are positively associated with ZDM Practice, while Chief Executive Officer (CEO) Duality of Power has a negative impact. In the millennium development goals period, the foremost drivers of ZDM Practice are Board Independence, Board Gender Diversity and Board Skills on Sustainable Manufacturing, while this shifted to Board Independence and Board Gender Diversity in the sustainable development goals period.
Originality/value
The study provides empirical evidence that organisations seeking to improve sustainable manufacturing practice may consider strengthening their CG structures to demonstrate responsible manufacturing in line with stakeholders’ expectations and to preserve corporate legitimacy. The results are robust to alternative proxies, potential endogeneity concerns and sample selection bias.
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P.S. Raghu Kumari, Harnesh Makhija, Dipasha Sharma and Abhishek Behl
The study aims to identify the impact of board characteristics (BC) on a firm's environmental performance, and provides future research directions in the area of BC impact on…
Abstract
Purpose
The study aims to identify the impact of board characteristics (BC) on a firm's environmental performance, and provides future research directions in the area of BC impact on environmental disclosures (ED) in case of India's environmentally sensitive and non-sensitive industries (SI and NSI).
Design/methodology/approach
The authors collect firm-level data from Prowess and Bloomberg, which cover 1,158 firm-year observations from National Stock Exchange of India (NSE) 500 listed companies from 2015 to 2020, and use a dynamic panel regression analysis to get deeper insights on the relationship of ED and BC.
Findings
The study found that lagged environment disclosure score is positively and significantly associated with current environmental disclosure scores. The presence of sustainability committee, board size and frequency of meetings has a positive and significant association with ED for sensitive as well as non-sensitive industry groups. Factors such as board Independence, board gender diversity and CEO duality have no significant impact on ED of both sensitive and non-sensitive industry groups.
Originality/value
Based on agency theory and stakeholder theory authors study for the first time in the context of India the effect of BC on ED using a large sample and covering an extensive period of six years. This study contributes by offering deep insights about the impact in case of “environmentally sensitive, non-sensitive and also all industries case”. The findings of this study are valuable for corporate managers and regulators who are interested in improving ED practices through a better-governed corporate mechanism.
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Yumo Wang, Zhifeng Liu, Ligang Cai and Qiang Cheng
This paper aims to study the nonlinear supporting performance of hydrostatic ram under the impact of cutting force and search for an optimal solution to improve its stiffness.
Abstract
Purpose
This paper aims to study the nonlinear supporting performance of hydrostatic ram under the impact of cutting force and search for an optimal solution to improve its stiffness.
Design/methodology/approach
The Reynolds equation was applied to resolve the carrying capability of a single oil pad numerically, and an iteration method was used to analyze the nonlinear supporting force and stiffness of a pair of oil pads placed face-to-face. The total offset of ram could be obtained after the displacement of aspectant oil pads was solved by the bisection method. From the comparison of the offset values of ram evaluated under different support conditions, the optimal solution was determined.
Findings
In this study, an optimized oil supply allocation, concluded as 1.16:0.84, is proposed to improve the performance of hydrostatic ram supporting structure.
Originality/value
The supporting performance of hydrostatic ram could be improved by appropriate allocation of oil supply without extra energy consumption.