Search results

Bat algorithm (BA) is a global optimization method, but has a worse performance on engineering optimization problems. The purpose of this study is to propose a novel chaotic bat algorithm based on catfish effect (CE-CBA), which can effectively deal with optimization problems in real-world applications.

Incorporating chaos strategy and catfish effect, the proposed algorithm can not only enhance the ability for local search but also improve the ability to escape from local optima traps. On the one hand, the performance of CE-CBA has been evaluated by a set of numerical experiment based on classical benchmark functions. On the other hand, five benchmark engineering design problems have been also used to test CE-CBA.

The statistical results of the numerical experiment show the significant improvement of CE-CBA compared with the standard algorithms and improved bat algorithms. Moreover, the feasibility and effectiveness of CE-CBA in solving engineering optimization problems are demonstrated.

This paper proposed a novel BA with two improvement strategies including chaos strategy and catfish effect for the first time. Meanwhile, the proposed algorithm can be used to solve many real-world engineering optimization problems with several decision variables and constraints.

As a kind of NP-hard combinatorial optimization problem, pipe routing design (PRD) is applied widely in modern industries. In the offshore oil and gas industry, a semi-submersible production platform is an important equipment for oil exploitation and production. PRD is one of the most key parts of the design of semi-submersible platform. This study aims to present an improved ant colony algorithm (IACO) to address PRD for the oil and gas treatment system when designing a semi-submersible production platform.

First, to simplify PRD problem, a novel mathematical model is built according to real constraints and rules. Then, IACO, which combines modified heuristic function, mutation mechanism and dynamical parameter mechanism, is introduced.

Based on a set of specific instances, experiments are carried out, and the experimental results show that the performance of IACO is better than that of two variants of ACO, especially in terms of the convergence speed and swarm diversity. Finally, IACO is used to solve PRD for the oil and gas treatment system of semi-submersible production platform. The simulation results, which include nine pipe paths, demonstrate the practicality and high-efficiency of IACO.

The main contribution of this study is the development of method for solving PRD of a semi-submersible production platform based on the novel mathematical model and the proposed IACO.

With the urbanization development in China, natural ecological environment and ecological environments in rural areas have been affected. Therefore, the characteristics and classification of rural greenway were analyzed on the basis of eco economic model theory, the resources of ecological, cultural, recreational and industrial greenway planning were evaluated, and the structure characteristics of rural greenway network are analyzed. A mathematical model of space superposition analysis is constructed. Taking SunYea town of Feixian county in Shandong as the object, starting from the green road network space, greenway system, service facilities, transfer system and identification system and other aspects, the construction of the rural greenway was carefully planned. Practice has proved that rural greenway planning research has improved the scientific nature of the allocation of resources, and has a certain exemplary role for the construction of rural greenway network in similar areas.

This paper aims to investigate the impact of retailer innovation investment and its spillover’s effect on competitive dual-channel supply chain pricing and optimization strategy, and explore the coordination mechanism considering decision maker’s bargaining ability.

The Cournot and Stackelberg game methodology are made use of for the duopoly decentralized and joint decision-making model. The bargaining theory with different negotiation ability was used to analysis the coordination mechanism. Then this paper validates the model by simulation techniques.

The results enlightened some interesting facts, the increase in innovation demand coefficient spur rise in channel pricing, innovation investment level, supply chain profit and consumer welfare. The rise in innovation spillover coefficient leads to increase in online channel pricing, supply chain profit and consumer welfare. Due to the innovation spillover effect, retailer has to maintain channel competitiveness either through low price or high innovation investment strategies. In addition, online channel pricing, supply chain profit and consumer welfare in joint decision-making scenario is greater than that of decentralized decision-making scenario, while the difference in retailer channel pricing depends on parameters value. The increase in retailer’s joint negotiation factor leads to decrease in channel pricing and innovation investment level. Furthermore, there existence of an optimal innovative investment cost sharing proportion threshold indicates the achievement of dual-channel supply chain coordination. A refinement equilibrium can be achieved through Robinstein bargaining game. A larger interest discount factor leads to decrease in profit.

The research provides a theoretical reference for dual-channel supply chain pricing and coordination strategy under channel competition environment. The research can develop innovative investment strategies for retailers and implement response strategies for manufacturers.

With the increase in uncertainty around the globe, an intensifying interest is seen in Economic Policy Uncertainty (EPU) as a topic of research. Researchers worldwide understand the significance of the impact of EPU on the country's development. EPU has a far-reaching impact as uncertainty shocks in one part of the world resonate worldwide due to the level of interconnectivity, globalization and quick communication. In order to facilitate these researchers, this study presents a bibliometric analysis of the existing research in this field using VOS viewer software, by consolidating all the studies from Scopus indexed journal articles, conference proceedings and review papers published in English language from 2006 to 2022. Bibliometric analysis on EPU has rarely been performed. The analysis identifies the publication trends, journal-wise citation, most influential authors, countries, institutions, keyword co-occurrence and authors of different countries who have collaborated for the research in the field. Finally, 1,055 papers were used for bibliometric analysis. The findings depicted that the most cited article on EPU is ‘Measuring economic policy uncertainty’ by Baker et al. (2016) and the most prolific author appears to be Rangan Gupta from University of Pretoria which as an institution also has the maximum publications on this topic. The Journal Finance Research Letters has published the greatest number of researches on EPU. This chapter also summarizes the limitations of the study along with new areas of research.

The implied assembly constraints of a computer-aided design (CAD) model (e.g. hierarchical constraints, geometric constraints and topological constraints) represent an important basis for product assembly sequence intelligent planning. Assembly prior knowledge contains factual assembly knowledge and experience assembly knowledge, which are important factors for assembly sequence intelligent planning. This paper aims to improve monotonous assembly sequence planning for a rigid product, intelligent planning of product assembly sequences based on spatio-temporal semantic knowledge is proposed.

A spatio-temporal semantic assembly information model is established. The internal data of the CAD model are accessed to extract spatio-temporal semantic assembly information. The knowledge system for assembly sequence intelligent planning is built using an ontology model. The assembly sequence for the sub-assembly and assembly is generated via attribute retrieval and rule reasoning of spatio-temporal semantic knowledge. The optimal assembly sequence is achieved via a fuzzy comprehensive evaluation.

The proposed spatio-temporal semantic information model and knowledge system can simultaneously express CAD model knowledge and prior knowledge for intelligent planning of product assembly sequences. Attribute retrieval and rule reasoning of spatio-temporal semantic knowledge can be used to generate product assembly sequences.

The assembly sequence intelligent planning example of linear motor highlights the validity of intelligent planning of product assembly sequences based on spatio-temporal semantic knowledge.

The spatio-temporal semantic information model and knowledge system are built to simultaneously express CAD model knowledge and assembly prior knowledge. The generation algorithm via attribute retrieval and rule reasoning of spatio-temporal semantic knowledge is given for intelligent planning of product assembly sequences in this paper. The proposed method is efficient because of the small search space.

The purpose of this study is to develop a monolayer surface coating of stearic acid on Sn-Ag-Cu solder powder to limit oxidation.

Stearic acid was adsorbed onto Sn-Ag-Cu solder powder through liquid-phase adsorption. The isotherm of adsorption was measured and then the microstructure of coated powder was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy.

The adsorption isotherm of stearic acid on the powder was “H” type, which revealed the layer-by-layer adsorption on non-porous surface. When the concentration of solution was in the range of 0.001-0.006 mol/L, with an adsorption amount of 0.12 ± 0.1 mg/g, monolayer stearic acid covered the solder powder completely. Uniform and integrated self-assembled monolayer coating was formed through hydrogen bonds between the oxygen ions in surface lattice of Sn3.0Ag0.5Cu solder powder and the —O—H hydroxyl group of stearic acid. The maximum angle of stability of coated powder also reduced by 2.87° compared with that of non-coated powder. The increase rate of oxygen content of coated powder was much slower than that of non-coated powder when they were exposed to humid air.

As a result, oxidation of fine solder powder was effectively limited. Essentially, this method can also be applied to the coating of other types of solder powder and has reference significance to other coating by liquid-phase method.

The main objective of the paper is to explore the theoretical correlation of base oil viscosity in grease and to study the effect of grease grade on mechanical vibrations associated with the damaged rolling bearings.

For theoretical purposes, formulation theory of dimensional analysis was implemented. Experiments were then performed on the test bearings lubricated with three different types of greases, namely, SKF LGHP2, SKF LGMT3 and SKF LGWA2.

The numerical results obtained from the theoretical model along with the results of experiments show that the vibration amplitudes of the defective bearings come down to a lower level when it is lubricated with the grease of a higher base oil viscosity.

The promising results from the theoretical model make it usable for the practical rotating machineries applying a variety of the rolling bearings. Consequently, if the bearing is not severely damaged, its performance can be increased by lubricating it with thicker grease.

Despite many significant contributions in the field to detect the presence of defects, not many studies have been performed that relate the lubrication condition of the rolling bearings with the vibration response, because around 50-75% of the bearing failures are attributed to be lubrication related. Hence, there is need to develop a mathematical model that can correlate the vibration severity of the bearings with viscosity of the lubricant oil in the greases along with other design and operating parameters.

The purpose of this paper is to describe a proposed framework for traceability purpose. Hence, the framework provides a formal and structured way of viewing a traceability solution. This structure lays the required bases for a traceability system before starting development and deployment.

The paper examines several traceability publications, including systems and literature review. The study covers the traceability implementation phase. Therefore, this research approaches the traceability issue from three perspectives (description, engineering and executive one). The separation between aspects is essential when describing and comparing traceability systems. This distinction is also helpful when recommending solution improvements.

The framework identifies six traceability bases: aims, functions, specifications, data classification, processes and procedures. These can establish a basis for a general purpose tool that can enable users to develop an efficient traceability solution. Thus, the first ontology expresses the framework domain and ensures optimal use of it. The second one represents the bases that can serve as a knowledge base to manage the product data.

The suggested framework tackles the implementation of traceability. Therefore, the design emphasizes the importance of technological concerns. Some studied cases could require more research angles (i.e. economic and legislative). Thus, framework enrichment is essential for further improvements.

The framework helps users to develop a general, interoperable and scalable traceability solution. These are important to promote the generalization of traceability systems.

The framework fulfills a requirement for establishing general traceability foundations. Therefore, the guide independently operates of the product or the industry specificity. Moreover, the bases aim to bridge the gap between solution engineering and traceability requirements.