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Rigidity of formation is an important concept in multi‐agent localization and control problems. The purpose of this paper is to design the control laws to enable the group to asymptotically exhibit the flocking motion while preserving the network rigidity at all times.

The novel approach for designing control laws is derived from a smooth artificial potential function based on an undirected infinitesimally rigid formation which specifies the target formation. Then the potential function is used to specify a gradient control law, under which the original system then becomes an orderly infinitesimally rigid formation.

The strong relationship between the stability of the target formation and the gradient control protocol are utilized to design the control laws which can be proved to make the target formation stable. However, the rigidity matrix is not utilized in the design of control law. Future research will mainly focus on formation control with the relationship of rigidity matrix.

The value of this paper is focused on the control laws design and the control laws could enable the group to asymptotically exhibit the flocking motion while preserving the network rigidity at all times. Also the detailed simulations and experiments are given to prove that the novel approach is available.

This study aims to focus on the heat treatment influence on the corrosion resistance, adhesion of Streptococcus mutans and mechanical properties of CoCrMo alloys manufactured by the selective laser melting (SLM).

CoCrMo alloys were manufactured using the Dimetal-100 machine. X-ray diffraction (XRD), metallographic analysis, scanning electron microscopy (SEM), electrochemical corrosion, Vickers microhardness and tensile tests were used to characterize SLM-produced CoCrMo alloys and compare them with the ones manufactured by casting and with the ASTM F75 standard.

The electrochemical results showed that SLM900 samples had the best corrosion resistance in artificial saliva. The adhesion results showed least propagation and overall quantity of Streptococcus mutans on the SLM900 sample. The microhardness, tensile and yield strength of As-SLM, SLM900 and SLM1200D samples were measured according to the ASTM F75 standard. The elongation of SLM900 was less than 8 per cent, which does not meet the standard specifications. Analysis of the fracture morphology showed that the fracture mechanisms of As-SLM and SLM1200D belong to the quasi-cleavage fracture type, and the mechanical fracture mechanism of SLM900 can be characterized as brittle fracture.

This paper presents the adhesion properties of Streptococcus mutans on the surface of CoCrMo alloys manufactured by SLM and proposes how to regulate the effect of the heat treatment on the corrosion resistance and mechanical properties of CoCrMo alloys manufactured by SLM.

This paper aims to verify whether selective laser melting (SLM) could be used for manufacturing mold with conformal cooling channels and determine whether the mechanical properties development of SLM manufacturing maraging steel mold would be beneficial to improve the quality of mold.

A series of block specimens and cylindrical tensile specimens are manufactured by SLM, and then are heat treated by solution treatment (ST) and solution treatment + aging treatment (ST + AT), respectively. The development of microstructure, microhardness and tensile strength of specimens is investigated. Then, a mold with conformal cooling channels is designed and manufactured by SLM and machined after ST with microhardness decreasing.

The morphology of microstructure varies widely under different heat treatment. The microhardness and tensile strength decrease after ST with cellular structure broken, which is conducive to mechanical finishing for mold to improve surface accuracy. After that, the hardness and strength of the mold increase significantly by AT with the precipitation of Ni3Mo, Fe2Mo and Ni3Ti particles. The maraging steel mold with conformal cooling channels can be manufactured by SLM successfully. And the surface accuracy of mold could be improved easily by machining.

Compared with the traditional mold with simple cooling channels, the mold with conformal cooling channels can be manufactured by SLM directly. The hardness of maraging steel mold manufactured by SLM can be reduced through ST, which is conducive to mechanical finishing for overcoming the defect of low precision of SLM directly manufacturing mold. This provides a new way for manufacturing mold of high quality.

This study aims to examine the underlying mechanism of buyer–seller ties and salespeople’s performance. Also examined was the moderating effects of the density of the customer network in which the salesperson is embedded.

The study developed a framework incorporating five key variables: strength of ties, network benefits, network density, sales effectiveness and sales revenue. The framework was tested using data from insurance companies in China.

Process regression and stepwise regression results indicated that information, influence and solidarity benefit will mediate the effects of strength of ties on sales effectiveness both when taken as a set and separately. Information, influence and solidarity benefit will mediate the effects of strength of ties on sales revenue when taken as a set, but only influence will mediate the effect separately. In addition, the positive relationship between strength of ties and solidarity benefit is weaker when network density is high.

Sales managers should initiate trainings and workshops about how to obtain high-quality information from customers, improving influencing power and establishing solidarity with customers. Moreover, salespeople should avoid conducting business with a group of customers if they are densely connected to one another.

On the one hand, this study contributes to the underlying mechanism research on buyer–seller ties and sales performance. On the other hand, it contributes to the contingency research on sales performance and the development of social network theory.

This paper aims to summarize design rules based on the process characteristics of selective laser melting (SLM) and structural optimization and apply the design rules in the lightweight design of an aluminum alloy antenna bracket. The design goal is to reduce 30 per cent of the weight while maintaining the stress levels in the original part.

To reduce weight as much as possible, the titanium alloy with higher specific strength was selected during the process of optimization. The material distribution of the bracket was improved by the topology optimization design. The redesign for SLM was used to obtain an optimization model, which was more suitable for SLM. The component performance was improved by shape optimization. The modal analysis data of the structural optimization model were compared with those of the stochastic lightweight model to verify the structural optimization model. The scanning data were compared with those of the original model to verify whether the model was suitable for SLM.

Structural optimization design for antenna bracket realized the mass decrease of 30.43 per cent and the fundamental frequency increase of 50.18 per cent. The modal analysis data of the stochastic lightweight model and the structural optimization model indicated that the optimization performance of structural optimization method was better than that of the stochastic lightweight method. The comparison results between the scanning data of the forming part and the original data confirmed that the structural optimization design for SLM lightweight component could achieve the desired forming accuracy.

This paper summarizes geometric constraints in SLM and derives design rules of structural optimization based on the process characteristics of SLM. SLM design rules make structural optimization design more reasonable. The combination of structural optimization design and SLM can improve the performance of lightweight antenna bracket significantly.

In this paper, the mechanical properties and corrosion resistance of CoCr alloy fabricated by selective laser melting (SLM) were studied, and the changes of performance after porcelain sintering process were also analysed. This study is to point out the relationship between the microstructure, mechanical properties and corrosion resistance of CoCr alloys prepared by SLM after porcelain sintering process. In addition, the biosafety of the sintered CoCr alloy was evaluated.

The microscopic feature changes of CoCr alloy samples after porcelain sintering process were observed by DMI 5000 M inverted metallographic microscope and Nova Nano430 FE-SEM. Moreover, phase identification and determination were conducted by X-ray diffraction (XRD) using Smartlab X-ray diffractometer. The Vickers microhardness was measured on the HVS-30 microhardness tester, and tensile tests were carried out on a CM3505 electronic universal testing machine. The corrosion resistance was tested by a classical three-point electrode system electrochemical method, then the ion precipitation was measured by using an atomic absorption spectrometer of Z2000 7JQ8024.

The XRD results indicate that the transition of γ phase (FCC) to e phase (HCP) occurs during the porcelain sintering processing of CoCr alloy. Moreover, the Vickers microhardness of the upper surface and the side surface of the CoCr alloy sample was improved by more than 36%. In addition, the ultimate strength of CoCr alloy via porcelain sintering treatment was increase to 1,395.3 ± 53.0 MPa compared to 1,282.7 ± 10.1 MPa of unprocessed CoCr alloy. However, the corrosion resistance of CoCr alloy samples decreases after porcelain sintering process.

There are few studies on the relationship of microstructure, mechanical properties and corrosion resistance of CoCr alloys prepared by SLM after porcelain sintering process. In this study, the microstructure, mechanical properties and corrosion resistance of CoCr alloy after porcelain sintering process were studied, and the biosafety of the alloy was evaluated. The research found that it is feasible to apply CoCr alloy fabricated by SLM to dental medicine after porcelain sintering process.

The purpose of this study is focused on the mechanical properties of multi-materials porous structures manufactured by selective laser melting (SLM).

The Diamond structure was designed by the triply periodic minimal surface function in MATLAB, and multi-materials porous structures were manufactured by SLM. Compression tests were applied to analyze the anisotropy of mechanical properties of multi-materials porous structures.

Compression results show that the multi-materials porous structure has a strong anisotropy behavior. When the compression force direction is parallel to the material arrangement, multi-materials porous structure was compressed in a layer-by-layer way, which is the traditional deformation of the gradient structure. However, when the compression force direction is perpendicular to the material arrangement, the compression curves show a near-periodic saw-tooth waveform characteristic, and this kind of structure was compressed consistently. It is demonstrated that the combination with high strength brittle material and low strength plastic material improves compression mode, and plastic material plays a role in buffering fracture.

This research provides a new method for the design and manufacturing of multi-materials porous structures and an approach to change the compression behavior of the porous structure.

This study aims to focus on the optimized design and mechanical properties of gradient triply periodic minimal surface cellular structures manufactured by selective laser melting.

Uniform and gradient IWP and primitive cellular structures have been designed by the optimized function in MATLAB, and selective laser melting technology was applied to manufacture these cellular structures. Finite element analysis was applied to optimize the pinch-off problem, and compressive tests were carried out for the evaluation of mechanical properties of gradient cellular structures.

Finite element analysis shows that the elastic modulus of IWP increased as design parameter b increased, and then decreased when parameter b is higher than 5.5. The highest elastic modulus of primitive increased by 89.2% when parameter b is 6. The compressive behavior of gradient IWP and primitive shows a layer-by-layer way, and elastic modulus and first maximum compressive strength of gradient primitive are higher than that of gradient IWP. The effective energy absorption of gradient cellular structures increased as the average porosity decreased, and the effective energy absorption of gradient primitive is about twice than that of gradient IWP.

This paper presents an optimized design method for the pinch-off problem of gradient triply periodic minimal surface cellular structures.

The purpose of this paper is to provide additive manufacturing-based solutions for preparation of elastomeric foam with broaden compressive stress plateau.

Mechanic models are developed for obtaining designs of foam cell units with enhanced elastic buckling. An experimental approach is taken to fabricate the foams based on direct ink writing technique. Experimental and simulation data are collected to assist understanding of our proposals and solutions.

A simple tetragonal structured elastomeric foam is proposed and fabricated by direct ink writing, in which its cell unit is theoretically designed by repeating every four filament layers. The foam exhibits a broader stress plateau, because of the pronounced elastic buckling under compressive loading as predicted by the authors’ mechanic modeling. A two-stage stress plateaus as observed in the foam, being attributed to the dual elastic buckling of the cell units along two lateral directions of the XY plane during compression.

Future work should incorporate more microscopic parameters to tune the elastomeric foam for mechanic performance testing on linear elastic deformation and densification of polymer matrix.

Additive manufacturing offers an alternative to fabricate elastomeric foam with controlled cell unit design and therefore mechanics. Our results comment on its broad space for development such superior cushioning or damping material in the fields of vibration and energy absorption.

This work has contributed to new knowledge on preparation of high performance elastomeric foam by providing a better understanding on its cell structure, being printed using direct ink writing machines.

This paper aims to explain how contractual complexity, including contractual control, coordination and adaptation, makes a difference to the task and relationship conflict, and then, to investigate the moderating roles played by both, total interdependence and interdependence asymmetry, in altering the association between the two types of conflicts.

This study obtained data through a questionnaire survey in the Chinese construction industry and the final sample consisted of 232 responses. The data were analysed using hierarchy analysis using SPSS.

The results are as follows: first, higher contractual control and coordination reduce the level of relationship conflicts, and higher contractual coordination also reduces the level of task conflicts; second, task conflict positively affects relationship conflict; third, task conflict mediates the relationship between contractual coordination and relationship conflict; and finally, when total interdependence is higher, task conflict induces more relationship conflict. On the contrary, high interdependence asymmetry weakens the positive relationship between task and relationship conflicts.

This study highlights the importance of contracts in conflict management. The findings can guide practitioners in drafting suitable contracts to deal with task and relationship conflicts more effectively.

This study differentiates the effects of distinct components of contracts on task and relationship conflicts, and then reveals the contingent effects of interdependence on the relationship between task and relationship conflicts in inter-organisational transactions.