Chunliang Niu, Chunfei Bai, Liming Guo, BingZhuo Liu and Lei Chen
In order to improve the rationality of the design of carbon fiber composite riveting structures in engineering products and reduce physical tests, the stress changes of various…
Abstract
Purpose
In order to improve the rationality of the design of carbon fiber composite riveting structures in engineering products and reduce physical tests, the stress changes of various parts during the carbon fiber-reinforced polymer (CFRP) riveting process, the influence area of hole edge stress and the damage of CFRP plates were studied from the perspective of numerical simulation. The reasonable arrangement requirements of composite riveted structures, installation speed and damage characteristics of CFRP plates in engineering applications are obtained. The research results provide technical references for the design and installation of composite riveting structures in engineering products.
Design/methodology/approach
Taking the forming process of the riveted structure between countersunk blind rivets and CFRP plates as the research object, the forming principle of countersunk blind rivets and the damage characteristics of CFRP plates were analyzed. Using contact nonlinearity theory, the anisotropic material modeling method and the Hashin failure criterion, the stress changes in various parts during the riveted joint forming process, the influence area of stress at the hole edge of the rivet holes and the damage of the CFRP plates were analyzed.
Findings
Reasonable rivet layout spacing was obtained; the peak stress of the rivet assembly increases with the increase of the rivet installation speed, and the influence area of the hole edge on the CFRP plate is a circular area with an outward extension radius of 0∼6 mm. Therefore, the arrangement distance between rivets is greater than the ring area, the damage law and installation speed of CFRP plates are given, the damage extends inward from the first layer of the laminates and the installation speed of 15 mm/s can satisfy the requirement of riveting installation better.
Originality/value
The riveting and forming process under different speeds is analyzed from the perspective of numerical simulation, and the stress variation rule of each part of the rivet and the damage of the CFRP plate under each speed are obtained. Reasonable rivet arrangement requirements and installation speed were given. This study provides technical support for the rivet arrangement method and mechanical property analysis of CFRP riveted structures in complex engineering products.
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Chunliang Niu, BingZhuo Liu, Chunfei Bai, Liming Guo, Lei Chen and Jiwu Tang
In order to improve the efficiency and reliability of simulation analysis for composite riveting structures in engineering products, a comparative study was conducted on different…
Abstract
Purpose
In order to improve the efficiency and reliability of simulation analysis for composite riveting structures in engineering products, a comparative study was conducted on different forms of riveting simulation methods.
Design/methodology/approach
Five different rivent simulation models were established using the finite element method, including rigid element CE, flexible element Rbe3 and beam element, and their results were future compared and analyzed.
Findings
Under the given technical parameters, the simulation method of Rbe3 (with holes) + beam can meet the analysis requirements of complex engineering products in terms of the rationality of rivet load distribution, calculation error and relatively efficient modeling.
Originality/value
This study proposes a simulation method for the riveting structure of carbon fiber composite materials for engineering applications. This method can satisfy the simulation analysis requirements of transportation vehicles in terms of modeling time, computational efficiency and accuracy. The research can provide technical support for the riveting process and mechanical analysis between carbon fiber composite components in transportation products.
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Johnny Kwok Wai Wong, Mojtaba Maghrebi, Alireza Ahmadian Fard Fini, Mohammad Amin Alizadeh Golestani, Mahdi Ahmadnia and Michael Er
Images taken from construction site interiors often suffer from low illumination and poor natural colors, which restrict their application for high-level site management purposes…
Abstract
Purpose
Images taken from construction site interiors often suffer from low illumination and poor natural colors, which restrict their application for high-level site management purposes. The state-of-the-art low-light image enhancement method provides promising image enhancement results. However, they generally require a longer execution time to complete the enhancement. This study aims to develop a refined image enhancement approach to improve execution efficiency and performance accuracy.
Design/methodology/approach
To develop the refined illumination enhancement algorithm named enhanced illumination quality (EIQ), a quadratic expression was first added to the initial illumination map. Subsequently, an adjusted weight matrix was added to improve the smoothness of the illumination map. A coordinated descent optimization algorithm was then applied to minimize the processing time. Gamma correction was also applied to further enhance the illumination map. Finally, a frame comparing and averaging method was used to identify interior site progress.
Findings
The proposed refined approach took around 4.36–4.52 s to achieve the expected results while outperforming the current low-light image enhancement method. EIQ demonstrated a lower lightness-order error and provided higher object resolution in enhanced images. EIQ also has a higher structural similarity index and peak-signal-to-noise ratio, which indicated better image reconstruction performance.
Originality/value
The proposed approach provides an alternative to shorten the execution time, improve equalization of the illumination map and provide a better image reconstruction. The approach could be applied to low-light video enhancement tasks and other dark or poor jobsite images for object detection processes.
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The most recent and prestigious scientific research shows that nitrogen leaching caused by over-used nitrogen fertilizer rapidly acidifies all soil types in China, revolutionizing…
Abstract
Purpose
The most recent and prestigious scientific research shows that nitrogen leaching caused by over-used nitrogen fertilizer rapidly acidifies all soil types in China, revolutionizing the basic understanding of the mechanism of soil acidification. The purpose of this paper is to study the impact of nitrogen on soil acidity over the long run, which is the shadow price of nitrogen.
Design/methodology/approach
In a discrete dynamic programming model, this paper compares the nitrogen application and soil pH between optimal nitrogen control that takes the shadow price of nitrogen into consideration and myopic nitrogen control that ignores that shadow price. Using a five-year panel experimental data on a rapeseed-rice rotation, this paper simulates and numerically solves the dynamic model.
Findings
Both theoretically and empirically, this paper shows that the over-use of nitrogen and the decline in soil pH are explained by ignorance of the shadow price of nitrogen. Compared with optimal nitrogen control, myopic nitrogen control applies more nitrogen in total, resulting in lower soil pH. In addition, over-use in the first season contributes to soil acidification and the carry-over effects mitigate that problem.
Originality/value
This paper enriches the literature by extending the study of the environmental impact of nitrogen leaching to its impact on the long-term loss in agricultural production, providing a new theoretical framework in which to study soil acidification rather than conventionally treating soil acidification as a secondary consequence of acid rain, and showing the possibility of using nitrogen control to mitigate soil acidification when lime applications are not feasible due to socio-economic constraints.
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Shi Chen, Zhiyong Han, Qiang Zeng, Bing Wang, Liming Wang, Liuyang Guo and Yimin Shao
Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance…
Abstract
Purpose
Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance between friction pairs. This paper aims to propose a novel two-parameter evaluation method for HVD during the mixed lubrication stage. The objective is to develop an effective model that establishes the relationship between these parameters and the actual surface topography.
Design/methodology/approach
In the presented methods, the fractal features of the real manufacturing surface are calculated based on the power spectrum function by the ultra-depth three-dimensional microscope. After that, the hybrid friction model of the friction plate is established based on mixed elasto-hydrodynamic lubrication theory, boundary friction model and fractal theory. Then the torque and load bearing characteristics of the clutch are obtained, and the influences of the surface fractal features are investigated and discussed. Finally, the Weierstrass–Mandelbrot function is adopted for the surface topography characterization and evaluation.
Findings
The results indicate that the proposed method exhibits good accuracy, while the speed difference between the friction pair exceeds 2,500 rpm. It is concluded that this paper proposed a way to evaluate the torque and loading capacity of HVD considering the real manufacturing surface topography and is helpful for surface optimization.
Originality/value
The originality and value of this study lie in its development of a novel torque and load bearing capacity evaluation method for HVD in mixed lubrication stage, considering manufacturing surface topography and describing the real manufacturing surface.
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Liming Lin, Zhaoyang Guo and Chenxi Zhou
Despite service downgrades' undisputed practical relevance, service downgrades (e.g. customers shifting the price tier downward) have received surprisingly little attention from…
Abstract
Purpose
Despite service downgrades' undisputed practical relevance, service downgrades (e.g. customers shifting the price tier downward) have received surprisingly little attention from scholars. Previous studies have focussed on either the public policy issue of tiered pricing or optimal pricing by the service provider. Only a few studies have examined why customers shift across different price tiers and how such activities indicate their future behaviour.
Design/methodology/approach
Based on customer data collected from a major telecommunications company, the authors use a logistic regression model to investigate how two service modification levers (i.e. transaction- and relationship-level factors) influence the likelihood of service downgrade. The authors apply a survival model to study how service downgrades affect customer churn.
Findings
Transaction-level factors such as service usage (e.g. the frequency and recency of underuse experiences) are positively associated with the likelihood of a downgrade. However, relationship-level factors (e.g. relationship duration and customer status) are negatively associated with the likelihood of downgrades. Customers engaging in downgrades are more likely to churn in the future.
Originality/value
The authors focus on downgrade behaviour, which can be perceived as customers' choice to move down the price tier, which likely ruins the service provider's performance. The authors conceptualise two fundamental driving forces behind a service downgrade: the misfits between the actual usage and the service plan chosen and the deteriorating relationships. The authors' empirical findings on the factors influencing downgrades provide insights for service providers seeking to prevent such behaviour.
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Hanane Sebbaq and Nour-eddine El Faddouli
The purpose of this study is, First, to leverage the limitation of annotated data and to identify the cognitive level of learning objectives efficiently, this study adopts…
Abstract
Purpose
The purpose of this study is, First, to leverage the limitation of annotated data and to identify the cognitive level of learning objectives efficiently, this study adopts transfer learning by using word2vec and a bidirectional gated recurrent units (GRU) that can fully take into account the context and improves the classification of the model. This study adds a layer based on attention mechanism (AM), which captures the context vector and gives keywords higher weight for text classification. Second, this study explains the authors’ model’s results with local interpretable model-agnostic explanations (LIME).
Design/methodology/approach
Bloom's taxonomy levels of cognition are commonly used as a reference standard for identifying e-learning contents. Many action verbs in Bloom's taxonomy, however, overlap at different levels of the hierarchy, causing uncertainty regarding the cognitive level expected. Some studies have looked into the cognitive classification of e-learning content but none has looked into learning objectives. On the other hand, most of these research papers just adopt classical machine learning algorithms. The main constraint of this study is the availability of annotated learning objectives data sets. This study managed to build a data set of 2,400 learning objectives, but this size remains limited.
Findings
This study’s experiments show that the proposed model achieves highest scores of accuracy: 90.62%, F1-score and loss. The proposed model succeeds in classifying learning objectives, which contain ambiguous verb from the Bloom’s taxonomy action verbs, while the same model without the attention layer fails. This study’s LIME explainer aids in visualizing the most essential features of the text, which contributes to justifying the final classification.
Originality/value
In this study, the main objective is to propose a model that outperforms the baseline models for learning objectives classification based on the six cognitive levels of Bloom's taxonomy. In this sense, this study builds the bidirectional GRU (BiGRU)-attention model based on the combination of the BiGRU algorithm with the AM. This study feeds the architecture with word2vec embeddings. To prove the effectiveness of the proposed model, this study compares it with four classical machine learning algorithms that are widely used for the cognitive classification of text: Bayes naive, logistic regression, support vector machine and K-nearest neighbors and with GRU. The main constraint related to this study is the absence of annotated data; there is no annotated learning objective data set based on Bloom’s taxonomy's cognitive levels. To overcome this problem, this study seemed to have no choice but to build the data set.
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Chin How (Norman) Goh, Michael D. Short, Nanthi S. Bolan and Christopher P. Saint
Biosolids, the residual solids from wastewater treatment operations and once considered a waste product by the industry, are now becoming increasingly recognised as a…
Abstract
Biosolids, the residual solids from wastewater treatment operations and once considered a waste product by the industry, are now becoming increasingly recognised as a multifunctional resource with growing opportunities for marketable use. This shift in attitude towards biosolids management is spurred on by increasing volatility in energy, fertilizer and commodity markets as well as moves by the global community towards mitigating global warming and the effects of climate change. This chapter will provide an overview of current global biosolids practices (paired with a number of Australian examples) as well as discuss potential future uses of biosolids. Additionally, present and future risks and opportunities of biosolids use are highlighted, including potential policy implications.
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China is among one of the oldest civilizations in the world. The massive land mass of China also means that the Chinese people are subject to weather extremes as well as…
Abstract
China is among one of the oldest civilizations in the world. The massive land mass of China also means that the Chinese people are subject to weather extremes as well as topographical variety in a country which cuts across alpine heights, treacherous deserts, lush valleys, dusty plains and lengthy rivers. With these weather extremes as the backdrop, it is crucial for the Chinese people to develop appropriate environmental control techniques for their dwellings as well as to ensure the structural integrity of their buildings. This paper discusses the protection, heating, anti‐seismic and dampness techniques developed and implemented in ancient China. It also documents the measures taken by the ancient Chinese to ensure the structural integrity of their buildings. The examples highlighted in this paper suggest that the building science principles adopted in ancient China remain relevant in the construction industry today.
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Liming Xiao, Bin Han, Sainan Yang and Shuai Liu
The construction of industrial park in the current development model of circular economy has been widely regarded as one of the important modes of macroeconomic exploration all…
Abstract
The construction of industrial park in the current development model of circular economy has been widely regarded as one of the important modes of macroeconomic exploration all over the world. Therefore, the research on the application of multi-project management theory based on circular economy in the construction of industrial park was proposed in this paper. First, the circular economy and multi-project management theory were expounded in detail. Then, the geographical location of multi project management in Qingyuan recycled plastic industrial park in Guangdong Province and the distribution of each building community were explained. And on this basis, the construction of the park's production, plant areas, residential areas and the planning objectives after completion were analyzed in detail. On the basis of analysis, the multi project management model used in the park was explained. It is pointed out that the construction of the park should be based on its own planning and practical needs, and the appropriate multi project management model should be chosen.