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Additive manufacturing (AM) is revolutionizing the manufacturing industry due to several advantages and capabilities, including use of rapid prototyping, fabrication of complex geometries, reduction of product development cycles and minimization of material waste. As metal AM becomes increasingly popular for aerospace and defense original equipment manufacturers (OEMs), a major barrier that remains is rapid qualification of components. Several potential defects (such as porosity, residual stress and microstructural inhomogeneity) occur during layer-by-layer processing. Current methods to qualify AM parts heavily rely on experimental testing, which is economically inefficient and technically insufficient to comprehensively evaluate components. Approaches for high fidelity qualification of AM parts are necessary.

This review summarizes the existing powder-based fusion computational models and their feasibility in AM processes through discrete aspects, including process and microstructure modeling.

Current progresses and challenges in high fidelity modeling of AM processes are presented.

Potential opportunities are discussed toward high-level assurance of AM component quality through a comprehensive computational tool.

The purpose of this paper is to understand the boundary-spanning behaviors of Party organizations, and the processes and constraints of these behaviors in controlling worker unrest in Chinese resource-based state-owned enterprises in the “new work-unit system” using boundary-spanning theory.

This case study was carried out in a resource-based state-owned enterprise in the “new work-unit system” in China. The research utilized interviews and archival documents, and then coded and analyzed the data using NVivo.

In China, Party organizations’ boundary-spanning behaviors (PBSBs) in labor relations management are identified, and classified into the behaviors of the ambassador, task coordinator, and scout. Worker unrest can be controlled by these behaviors through the mediation effect of the behaviors of agents in the “new work-unit system” but can also be provoked in the transformation of the “new work-unit system.”

The Communist Party plays a key role in labor relations management in China’s SOEs; however, this role has not been explored in any depth. This study builds a model to reveal the “black box” in which the PBSBs influence the agents’ behaviors and how the agents’ behaviors then influence the workers, and in this way control worker unrest.

Regarding human resource and labour relations management, academia focuses mainly on cities; however, rural areas are an integral part of China's economic structure. This study focuses on the movie projection industry in China's rural areas and explores how human resource practices (HRPs) are transformed and the labour process is reconstructed in digital transformation.

We adopt a case study of a rural movie projection company. The company's HRPs reconstructed the labour process of movie projection, and they have been promoted as national standards. Data were collected from in-depth interviews, files and observations.

Rural movie projection companies combine high-performance and paternalistic HRPs in the media industry's digital transformation. HRPs and digital technology jointly reconstruct the labour process. First, the HRPs direct labour process practices towards standardisation. Second, the digital supervision platform guides the control style from simple to technical, placing projectionists under pressure while increasing management efficiency. Third, rural movies made using digital technology have disenchanted rural residents. Accordingly, the conventional relationships between the “country and its citizens,” “individuals themselves,” and “models and individuals” have been removed, and a new relationship between “individuals themselves” is formed thanks to the novel HRPs.

This research plays a crucial role in exposing researchers to the labour process of rural movie projection, which is significant in China but often ignored by Western academia and advances the Chinese contextualisation of research on labour relations.

This study explores labor relations management behaviors of administrators and Party organizations in resource-based state-owned enterprises (SOEs) in China based on social exchange theory and embeddedness theory. It builds up a process model for managing collective labor conflicts in resource-based SOEs in the Chinese context.

A comparative case study is conducted using two resource-based SOEs with similar backgrounds but differing in effectiveness of the management of collective labor conflicts. Data are collected from interviews, archival sources and a one-month participatory investigation.

The administrators and Party organizations of resource-based SOEs manage collective labor conflicts by means of human resource practices (HRPs) and Party organizations' boundary-spanning behaviors (PBSBs), respectively; foremen and unions perform a mediation role, especially under circumstances where administrators employ high-performance HRPs and PBSBs are closely integrated with the production process. The marketization of the “new danwei system” exerts a “provocation effect” but does not necessarily lead to collective labor conflicts. The root cause of conflicts lies in the inherent defects of specific HRPs and PBSBs, as well as the absence of the Simmelian tie in the social exchange interaction of actors.

First, this study develops a new construct of PBSBs for enterprises' Party organizations and explores its underlying mechanisms, which enriches the range of actors studied in the context of Chinese labor relations; Second, the authors develop a new dimension called “exemplification” building on the existing three-dimensional structure of boundary-spanning behaviors, which expands boundary-spanning theory. Third, the findings that Simmelian tie structure could better maintain the stability of labor relationship in the mediation process of labor-capital conflict management enrich the social exchange theory from the perspective of structure. Finally, this study deepens the existing research on HRPs by proposing a new explanation for disputes.

This paper aims to study the effect of different rare earth oxide on the tribological properties of polyimide (PI) nanocomposites based on the CNT and GO reinforcements.

The PI nanocomposites filled with different rare earth oxide based on the carbon nanotubes and graphene oxide were designed and prepared by hot press sintering. The mechanical and tribological properties of PI nanocomposites were carried out, and their reinforcement mechanisms were discovered.

Rare earth oxide had a weak influence on the impact strength of PI nanocomposites. Filling La₂O₃ can dramatically reduce the friction coefficient and wear rate of PI nanocomposites.

The PI nanocomposites filled with rare earth oxide based on the CNT and GO reinforcements were designed, and their mechanical and tribological properties were studied.

The purpose of this paper is to investigate the effect of SiO₂ on the tribological properties of polytetrafluoroethylene (PTFE) composites from an atomic level.

Effect of SiO₂ on the tribological properties of PTFE sliding against Cu was studied by molecular dynamics (MD) simulations to explore the inherent mechanisms from an atomic level.

SiO₂ had a higher interaction energy with PTFE than copper, which contributed to an increase of interfacial temperature and velocity with severe adhesive wear on the PTFE molecules.

This study reveals the mechanism of SiO₂ on the friction and wear behavior of PTFE by MD simulation.

The purpose of this paper is to investigate the effect of lanthana (La₂O₃) on the mechanical and tribological properties of polyimide (PI).

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.

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 La₂O_3, 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.

This study reveals the friction and wear mechanism of PI composites filled with rare earth oxide at the nanoscale.

The purpose of this paper is to propose a new joint friction model, which can accurately model the real friction, especially in cases with sudden changes in the motion direction. The identification and sensor-less control algorithm are investigated to verify the validity of this model.

The proposed friction model is nonlinear and it considers the angular displacement and angular velocity of the joint as a secondary compensation for identification. In the present study, the authors design a pipeline – including a manually designed excitation trajectory, a weighted least squares algorithm for identifying the dynamic parameters and a hand guiding controller for the arm’s direct teaching.

Compared with the conventional joint friction model, the proposed method can effectively predict friction factors during the dynamic motion of the arm. Then friction parameters are quantitatively obtained and compared with the proposed friction model and the conventional friction model indirectly. It is found that the average root mean square error of predicted six joints in the proposed method decreases by more than 54%. The arm’s force control with the full torque using the estimated dynamic parameters is qualitatively studied. It is concluded that a light-weight industrial robot can be dragged smoothly by the hand guiding.

In the present study, a systematic pipeline is proposed for identifying and controlling an industrial arm. The whole procedure has been verified in a commercial six DOF industrial arm. Based on the conducted experiment, it is found that the proposed approach is more accurate in comparison with conventional methods. A hand-guiding demo also illustrates that the proposed approach can provide the industrial arm with the full torque compensation. This essential functionality is widely required in many industrial arms such as kinaesthetic teaching.

First, a new friction model is proposed. Based on this model, identifying the dynamic parameter is carried out to obtain a set of model parameters of an industrial arm. Finally, a smooth hand guiding control is demonstrated based on the proposed dynamic model.

The purpose of this paper is to focus on compressive strength modelling of cementitious mixtures like mortar and Roller-compacted concrete (RCC) containing rubber aggregates from shredded worn tires and filler using adaptive neuro fuzzy inference systems (ANFIS).

The volume substitution contains a ratio of rubber aggregates vs sand in mortar and with crushed sand in RCC and ranges from 0 to 50 per cent. As for the filler, they are substituted with sand by 5 per cent in mortar mixture. The methodology consists of optimizing the percentage of substitution in cementitious mixtures to ensure better mechanical properties of materials like compressive strength. The prediction of compressive strength and the optimization of cementitious mixtures encourage their uses in such construction pavements, in area games or in other special constructions. These cementitious materials are considered as friendly to the environment by focussing on their improved deformability.

The results of this paper show that the performance of the constructed fuzzy method was measured by correlation of experimental and model results of mortar and RCC mixtures containing both rubber aggregates and filler. The comparison between elaborated models through the error and the accuracy calculations confirms the reliability of the ANFIS method.

The purpose of this paper is to assess the performance of the constructed fuzzy model by the ANFIS method for two types of cementitious materials like mortar and RCC containing rubber aggregates and filler. The fuzzy method could predict the compressive strength based on the limited measurement values in the mechanical experiment. Furthermore, the comparison between the elaborated models confirms the reliability of the ANFIS method through the error and the accuracy calculations for the best cementitious material mixtures.