Xinxing Yin, Juan Chen, Wenxin Yu, Yuan Huang, Wenxiang Wei, Xinjie Xiang and Hao Yan
This study aims to improve the complexity of chaotic systems and the security accuracy of information encrypted transmission. Applying five-dimensional memristive Hopfield neural…
Abstract
Purpose
This study aims to improve the complexity of chaotic systems and the security accuracy of information encrypted transmission. Applying five-dimensional memristive Hopfield neural network (5D-HNN) to secure communication will greatly improve the confidentiality of signal transmission and greatly enhance the anticracking ability of the system.
Design/methodology/approach
Chaos masking: Chaos masking is the process of superimposing a message signal directly into a chaotic signal and masking the signal using the randomness of the chaotic output. Synchronous coupling: The coupled synchronization method first replicates the drive system to get the response system, and then adds the appropriate coupling term between the drive The synchronization error and the coupling term of the system will eventually converge to zero with time. The synchronization error and coupling term of the system will eventually converge to zero over time.
Findings
A 5D memristive neural network is obtained based on the original four-dimensional memristive neural network through the feedback control method. The system has five equations and contains infinite balance points. Compared with other systems, the 5D-HNN has rich dynamic behaviors, and the most unique feature is that it has multistable characteristics. First, its dissipation property, equilibrium point stability, bifurcation graph and Lyapunov exponent spectrum are analyzed to verify its chaotic state, and the system characteristics are more complex. Different dynamic characteristics can be obtained by adjusting the parameter k.
Originality/value
A new 5D memristive HNN is proposed and used in the secure communication
Details
Keywords
Heng Xiao, Wei-Hao Yan, Lin Zhan and Si-Yu Wang
A new and explicit form of the elastic strain-energy function for modeling large strain elastic responses of soft solids is constructed based on Hencky's logarithmic strain tensor.
Abstract
Purpose
A new and explicit form of the elastic strain-energy function for modeling large strain elastic responses of soft solids is constructed based on Hencky's logarithmic strain tensor.
Design/methodology/approach
Well-designed invariants of the Hencky strain are introduced for characterizing deformation modes and, furthermore, a new interpolating technique is proposed for combining piecewise splines into a single smooth function.
Findings
With this new form and this new technique, objectives in three respects may be achieved for the first time.
Originality/value
First, no adjustable parameters need to be treated. Second, large strain responses for three benchmark modes are derivable in a decoupled sense without involving strongly nonlinear coupling effects. Finally, large strain data may be automatically and accurately matched for three benchmark modes, including uniaxial, equi-biaxial and plane-strain extension. Numerical examples are presented and compared with usual approaches.
Details
Keywords
The purpose of this paper is to provide a critical historical analysis of the business (mis)behaviors and influencing factors that discourage enduring cooperation between…
Abstract
Purpose
The purpose of this paper is to provide a critical historical analysis of the business (mis)behaviors and influencing factors that discourage enduring cooperation between principals and agents, to introduce strategies that embrace the social values, economic motivation and institutional designs historically adopted to curtail dishonest acts in international business and to inform an improved principal–agent theory that reflects principal–agent reciprocity as shaped by social, political, cultural, economic, strategic and ideological forces
Design/methodology/approach
The critical historical research method is used to analyze Chinese compradors and the foreign companies they served in pre-1949 China.
Findings
Business practitioners can extend orthodox principal–agent theory by scrutinizing the complex interactions between local agents and foreign companies. Instead of agents pursuing their economic interests exclusively, as posited by principal–agent theory, they also may pursue principal-shared interests (as suggested by stewardship theory) because of social norms and cultural values that can affect business-related choices and the social bonds built between principals and agents.
Research limitations/implications
The behaviors of compradors and foreign companies in pre-1949 China suggest international business practices for shaping social bonds between principals and agents and foreign principals’ creative efforts to enhance shared interests with local agents.
Practical implications
Understanding principal–agent theory’s limitations can help international management scholars and practitioners mitigate transaction partners’ dishonest acts.
Originality/value
A critical historical analysis of intermediary businesspeople’s (mis)behavior in pre-1949 (1840–1949) China can inform the generalizability of principal–agent theory and contemporary business strategies for minimizing agents’ dishonest acts.
Details
Keywords
Myranda Spratt, Sudharshan Anandan, Rafid Hussein, Joseph W. Newkirk, K. Chandrashekhara, Misak Heath and Michael Walker
The purpose of this study is to analyze the build quality and compression properties of thin-walled 304L honeycomb structures manufactured by selective laser melting. Four…
Abstract
Purpose
The purpose of this study is to analyze the build quality and compression properties of thin-walled 304L honeycomb structures manufactured by selective laser melting. Four honeycomb wall thicknesses, from 0.2 to 0.5 mm, were built and analyzed.
Design/methodology/approach
The density of the honeycombs was changed by increasing the wall thickness of each sample. The honeycombs were tested under compression. Differences between the computer-assisted design model and the as-built structure were quantified by measuring physical dimensions. The microstructure was evaluated by optical microscopy, density measurements and microhardness.
Findings
The Vickers hardness of the honeycomb structures was 209 ± 14 at 50 g load. The compression ultimate and yield strength of the honeycomb material were shown to increase as the wall thickness of the honeycomb samples increased. The specific ultimate strength also increased with wall thickness, while the specific yield stress of the honeycomb remained stable at 42 ± 2.7 MPa/g/cm3. The specific ultimate strength minimized near 0.45 mm wall thickness at 82 ± 5 MPa/g/cm3 and increased to 134 ± 3 MPa/g/cm3 at 0.6 mm wall thickness.
Originality/value
This study highlights a single lightweight metal structure, the honeycomb, built by additive manufacturing (AM). The honeycomb is an interesting structure because it is a well-known building material in the lightweight structural composites field but is still considered a relatively complex geometric shape to fabricate. As shown here, AM techniques can be used to make complex geometric shapes with strong materials to increase the design flexibility of the lightweight structural component industry.
Details
Keywords
Jianfeng Sun, Zhou Yang, Yongqiang Yang and Di Wang
This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting…
Abstract
Purpose
This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting (SLM).
Design/methodology/approach
This paper includes processing the matrix and overhanging structure with optimized parameters and analyzing the microstructure and properties of matrix and overhanging with OM, SEM, XRD etc. so as to analyze and reveal the laws and mechanism of overhanging structure formed by SLM.
Findings
The solidification of overhanging structure begins from the structure’s edge and extends to its center; the distribution of the Cr with a diameter of 250 nm in the Fe matrix is uniform; the grain in the overhanging structure is growing faster than the grain in the matrix. The overhanging structure mainly composed by austenite has no apparent layer. Moreover, the microhardness of the overhanging structure is 258.6-294.0 Hv0.3, smaller than the microhardness of the matrix which is 236.4-300.9 Hv0.3.
Originality/value
This paper clarifies how to manufacture overhanging structure and non-overhanging structure matrix with optimized parameters, analyzes the microstructures and compares the properties of both overhanging structure and non-overhanging structure “matrix”, so as to analyze the reasons for the forming of the overhanging structure, which in turn lauds basic data foundation for the theoretical studies in the future.
Details
Keywords
Giampaolo Campana, Eckart Uhlmann, Mattia Mele, Luca Raffaelli, André Bergmann, Jaroslaw Kochan and Julian Polte
Support structures used in laser powder bed fusion are often difficult to clean from unsintered powder at the end of the process. This issue can be significantly reduced through a…
Abstract
Purpose
Support structures used in laser powder bed fusion are often difficult to clean from unsintered powder at the end of the process. This issue can be significantly reduced through a proper design of these auxiliary structures. This paper aims to investigate preliminary the airflow within differently oriented support structures and to provide design guidelines to enhance their cleanability, especially the depowdering of them.
Design/methodology/approach
This study investigates the cleanability of support structures in powder bed fusion technology. Digital models of cleaning operations were designed through computer-aided engineering systems. Simulations of the airflow running into the powder entrapped within the thin walls of auxiliary supports were implemented by computational fluid dynamics. This approach was applied to a set of randomly generated geometrical configurations to determine the air turbulence intensity depending on their design.
Findings
The results, which are based on the assumption that a relationship exists between turbulence and powder removal effectiveness, demonstrated that the maximum cleanability is obtainable through specific relative rotations between consecutive support structures. Furthermore, it was possible to highlight the considerable influence of the auxiliary structures next to the fluid inlet. These relevant findings establish optimal design rules for the cleanability of parts manufactured by powder bed fusion processes.
Originality/value
This study presents a preliminary investigation into the cleanability of support structures in laser powder bed fusion, which has not been addressed by previous literature. The results allow for a better understanding of the fluid dynamics during cleaning operations. New guidelines to enhance the cleanability of support structures are provided based on the results of simulations.
Details
Keywords
Danna Tang, Yushen Wang, Zheng Li, Yan Li and Liang Hao
The low-temperature sintering of silica glass combined with additive manufacturing (AM) technology has brought a revolutionary change in glass manufacturing. This study aims to…
Abstract
Purpose
The low-temperature sintering of silica glass combined with additive manufacturing (AM) technology has brought a revolutionary change in glass manufacturing. This study aims to carry out in an attempt to achieve precious manufacturing of silicate glassy matrix through the method of slurry extrusion.
Design/methodology/approach
A low-cost slurry extrusion modelling technology is used to extrude silicate glassy matrix inks, composed of silicate glass powder with different amounts of additives. Extrudability of the inks, their printability window and the featuring curves of silicate glassy matrix are investigated. In addition, the properties of the low-temperature sintering green part as a functional part are explored and evaluated from morphology, hardness and colour.
Findings
The results showed that the particle size was mainly distributed from 1.4 µm to 5.3 µm, showing better slurry stability and print continuity. The parameters were set to 8 mm/s, 80% and 0.4 mm, respectively, to achieve better forming of three-dimensional (3D) samples. Besides, the organic binder removal step was concentrated on 200°C–300°C and 590°C–650°C was the fusion bonding temperature of the powder. The hardness values of 10 test samples ranged from 588 HL to 613 HL, which met the requirements of hard stones with super-strong mechanical strength. In addition, the mutual penetration of elements caused by temperature changes may lead to a colourful appearance.
Originality/value
The custom continuous AM technology enables the fabrication of a glass matrix with 3D structural features. The precise positioning technology of the glass matrix is expected to be applied more widely in functional parts.
Details
Keywords
Yunsong Shi, Wei Zhu, Chunze Yan, Jinsong Yang and Zhidao Xia
This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution…
Abstract
Purpose
This study aims to report the preparation, selective laser sintering (SLS) processing and properties of a new nylon elastomer powder. The effects of solvent, dissolution temperature and time and cooling method and speed on the particle size and morphologies of the prepared nylon elastomer powder are investigated.
Design/methodology/approach
The prepared nylon elastomer power possesses the particle size of around 50 mm and is spherical in shape, indicating that this study provides the feasible dissolution-precipitation process, a distillation cooling method and a suitable solvent to prepare nylon elastomer powders.
Findings
Compared to pure nylon 12, the nylon elastomer has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates the better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.
Originality/value
The nylon elastomer in this study has a lower part bed temperature and a wider sintering window for the SLS process. The wider sintering window indicates better SLS processibility. The lower part bed temperature is beneficial to the recycling of material and the decrease in the requirement of SLS equipment.
Details
Keywords
Shih‐Hao Shen, Yueh‐Min Huang and Jen‐Wen Ding
Wireless mesh networks (WMNs) are regarded as a milestone in developing next‐generation wireless networks. The multi‐hop architecture of WMN makes it very attractive. However…
Abstract
Purpose
Wireless mesh networks (WMNs) are regarded as a milestone in developing next‐generation wireless networks. The multi‐hop architecture of WMN makes it very attractive. However, interoperability is an inherent problem for deploying a large‐scale WMN, which may consist of various types of wireless networks. There are two intuitive approaches to solving the interoperability problem: the dual‐stack/multi‐stack approach and the naive layer‐2 broadcast approach. While the former incurs high cost in all devices, the latter creates broadcast storm in the whole network. This paper aims to propose a cross‐layer heterogeneous routing protocol for solving this problem without the adverse effects of the intuitive approaches.
Design/methodology/approach
A conceptual discussion and approach are employed.
Findings
The simulation results validate the efficiency of the proposed protocol.
Originality/value
The paper provides details of a method for routing selection in WMNs.
Details
Keywords
Hamza Hassn Alsalla, Christopher Smith and Liang Hao
The purpose of this paper is to investigate the density, surface quality, microstructure and mechanical properties of the components of the selective laser melting (SLM) parts…
Abstract
Purpose
The purpose of this paper is to investigate the density, surface quality, microstructure and mechanical properties of the components of the selective laser melting (SLM) parts made at different building orientations. SLM is an additive manufacturing technique for three-dimensional parts. The process parameters are known to affect the properties of the eventual part. In this study, process parameters were investigated in the building of 316L structures at a variety of building orientations and for which the fracture toughness was measured.
Design/methodology/approach
Hardness and tensile tests were carried out to evaluate the effect of consolidation on the mechanical performance of specimens. Optical and electron microscopy were used to characterise the microstructure of the SLM specimens and their effects on properties relating to fracture and the mechanics. It was found that the density of built samples is 96 per cent, and the hardness is similar in comparison to conventional material.
Findings
The highest fracture toughness value was found to be 176 MPa m^(1/2) in the oz. building direction, and the lowest value was 145 MPa m^(1/2) in the z building direction. This was due to pores and some cracks at the edge, which are slightly lower in comparison to a conventional product. The build direction does have an effect on the microstructure of parts, which subsequently has an effect upon their mechanical properties and surface quality. Dendritic grain structures were found in oz. samples due to the high temperature gradient, fast cooling rate and reduced porosity. The tensile properties of such parts were found to be better than those made from conventional material.
Originality/value
The relationship between the process parameters, microstructure, surface quality and toughness has not previously been reported.