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The purpose of this paper is to improve the bearing capacity and mechanical properties of the oil pocket.

In this paper, a straight-through labyrinth seal is installed in an oil sealing belt. The main structure of hydrostatic support system (HSS) is introduced, and the factors affecting the leakage loss are analyzed. The governing equations involving the momentum equation and the continuity equation for the land section and groove section are established separately based on the three-control-volume theory. To explain the flow capability of the straight-through labyrinth seal, the labyrinth seal with different clearance widths, groove numbers, groove depths and pressure difference is calculated. The results of the simulation are compared and analyzed.

The groove dimensions and groove numbers have important impact on the leakage and flow pattern of the seal.

The fluid flow was simulated by commercial tools executed in the ANSYS Fluent, the computational fluid dynamics (CFD) solver and a steady state scheme with the realizable k-ε turbulence model was applied. The cavity structure of the straight-through labyrinth seal, forming turbulence eddy flows in the groove, which is a valid approach to convert turbulence kinetic energy into thermal energy, reduce leakage mass flow.

This research can provide the theoretical basis and technical support which is conducive to the practical application of the straight-through labyrinth seal in HSS.

A new design structure is proposed to improve the bearing capacity and economic benefit of HSSs.

A straight-through labyrinth seal is applied to the oil sealing belt and the three-control-volume governing equation is established.

This paper aims to study the dynamic characteristics of the straight-through labyrinth seals, which is applied on an oil sealing belt of hydrostatic support system (HSS) oil pocket, the establishment and solution process of seal governing equation is deduced.

The three-control-volume model theory is an efficient approach that is applied well. This paper starts with three relative governing equations for the flow characteristics of straight-through labyrinth seals in the plane direction. Referring to the establishment process of governing equations for circumferentially-grooved liquid seals, the governing equation based on space rectangular coordinate system is established, which are transformed into dimensionless equations through a nondimensionalized process and solved by a perturbation method. It contains a zeroth-order equation, through which a steady fluid distribution is determined, and a first-order equation, through which the seal’s dynamic coefficients can be acquired.

The governing equation for plane-grooved straight-through labyrinth seals can be established and solved by the three-control-volume theory.

This study have important guiding significance for further theoretical research and structural design of the straight-through labyrinth seals on the oil sealing belt of HSS oil pocket.

In this paper, a straight-through labyrinth seal is installed in an oil sealing belt. The three-control-volume governing equations is established in space rectangular coordinate system, and the shear force of the fluid Y-direction is different from the previous model.

Aiming at presenting an interaction-free assembly assistance tool, the purpose of this paper is to propose a synchronous augmented reality (AR) assembly assistance and monitoring system. The system monitors operator’s hands activity and process completeness to recognize the assembly state, then display the AR contents contextually.

An assembly behavior recognition method is proposed based on gesture recognition. An assembly completeness inspection method is proposed based on SURF feature matching. Assembly state and AR display state are solved by a novel sequential hybrid AR display control strategy. A synchronous multi-channel AR view output strategy is proposed based on QR matrix decomposition.

A prototype system has been developed, and case study is performed on an industrial product. Experiments are performed to verify the feasibility, efficiency and recognition accuracy of the proposed methods.

The proposed system assists users to perform assembly tasks with automatic visual guidance and vision monitoring, avoiding distractions caused by redundant human–computer interactions.

All methods are integrated to work on only one head-worn device, making the proposed system portable and cheaper. The vision processing pipelines and the view output channels are reconfigurable for customization.

This paper proposes an interaction-free AR assembly assistance and monitoring system. Assembly behavior recognition and assembly completeness inspection methods are integrated to monitor the assembly state. A sequential hybrid AR display control strategy is proposed to contextually update the AR contents. A synchronous multi-channel AR view output strategy is proposed to fulfill different visualization needs.

The purpose of this paper is to develop a modeling and interactive operating method for virtual assembly (VA) to support assembly process generation based on interactive operation.

This paper puts forward an assembly semantic modeling method for interactive assembly and process generation after the analysis on requirements of operation process generation. Based on this semantic model, methods for semantic generation, semantic processing and assembly motion extraction from interactive operation are presented. Partial process generation of auto engine is proposed to verify the approaches in this paper.

The application shows that assembly semantic modeling and operating methods can support process generation based on VA operations.

The approaches presented in this paper improve the efficiency of assembly process, making assembly process intuitive and natural.

The paper aims to establish a virtual lighting maintenance environment (VLME), and to analyze the visibility-related human factors (HFs) during maintenance operations through interactive simulations.

First, an accurate task lighting modeling method was developed, which includes lighting information modeling and illuminant parameters calibration. Then, the real-time interaction between the task lighting and three-dimensional virtual human was modeled. After that, the attenuation coefficient of visibility was determined. Also, the HFs’ analysis process in VLME was described in detail.

A case study of power supply module replacement of radar equipment was performed in VLME. The HFs’ analysis demonstrated that the task lighting significantly affects the visibility, which causes indirect impact on posture comfort and operation safety.

Through evaluating maintenance operation processing in lighting environment, engineers can better analyze and validate the maintainability design for complex equipment, and some potential ergonomics and safety issues can be found and dealt earlier.

An VLME was built for interactive “human-in-loop” maintenance operation simulation, which can support HFs’ evaluation in lighting environment accurately and effectively.

The purpose of this paper is to give a comprehensive survey on the physics-based virtual assembly (PBVA) technology in a novel perspective, to analyze current drawbacks and propose several promising future directions.

To provide a deep insight of PBVA, a discussion of the developing context of PBVA and a comparison against constraint-based virtual assembly (CBVA) is put forward. The core elements and general structure are analyzed based on typical PBVA systems. Some common key issues as well as common drawbacks are discussed, based on which the research trend and several promising future directions are proposed.

Special attention is paid to new research progresses and new ideas concerning recent development as well as new typical systems of the technology. Advantages of PBVA over CBVA are investigated. Based on the analysis of typical PBVA systems and the evolution of PBVA, the core elements of the technology and the general structure of its implementation are identified. Then, current PBVA systems are summarized and classified. After that, key issues in the technology and current drawbacks are explored in detail. Finally, promising future directions are given, including both the further perfecting of the technology and the combination with other technologies.

The PBVA technology is put into a detailed review and analysis in a novel way, providing a better insight of both the theory and the implementation of the technology.

The paper aims to propose a systematic approach for human factors (HFs) automatic evaluation for entire maintenance processes in virtual environment.

First, a maintenance process information model is constructed to map real maintenance processes into computer environment. Next, based on this information model, the automatic evaluation methods for visibility, operation comfort and reachability are presented. All evaluation results are weighted and added up to establish a comprehensive HFs evaluation model. Then, the methods mentioned above are realized as an HFs evaluation module, which is integrated into virtual maintenance simulation platform, software developed by our lab.

An application in HFs evaluation of repairing hydraulic motor on container spreader is implemented, and an on-site survey is carried out. The comparison between the result from the survey and the result we get using the presented methods shows that our solution can support HFs fast assessment accurately and effectively.

Through evaluating maintenance operation processes, engineers can better analyze and validate the maintainability design of complex equipment, and some potential ergonomic issues can be found and dealt earlier.

The paper contributes to present a systematic approach to achieve HFs fast and accurate evaluation for entire maintenance processes, rather than for a few maintenance postures.

Automobile development needs more and more collaborative work involving geographical dispersed designers, that brings difficulty for model verification, conception review and assembly process evaluation, so a collaborative virtual environment for automobile based on network is required. In this kind of environment, designers can do interactive assembly operations collaboratively, such as grasp, move, release, collision detection (CD), assembly evaluation report generation, etc. Furthermore, automobile structure becomes more complicated, how to process this large real‐time data effectively in real‐time interactive virtual environment is a great challenge. The purpose of this paper is focus on this.

A distributed parallel virtual assembly environment (DPVAE) is developed. In this environment, the mechanism of event synchronization based on high‐level architecture/run‐time infrastructure) is applied to realize multi‐user collaboratively interactive operation. To meet the large data set real‐time processing demand, a creative parallel processing approach supported by a single supercomputer or a parallel processing environment composed of common personal computer in a high‐speed local area network is developed. The technologies such as real‐time CD, multiple interactive operation modals are applied in DPVAE and several auxiliary tools are provide to help achieving whole scheme review, component model verification and assembly evaluation.

This paper finds that DPVAE system is an available and efficient tool to support automobile collaborative assembly design.

Designers can discuss and verify the assembly scheme to realize the previous design scenario in DPVAE, so it is useful for reducing costs, improving quality and shortening the time to market, especially for new type automobile development.

A combination of distributed technology and parallel computing technology is applied in product virtual assembly, solving the problems including collaborative work of multi‐user and large data real‐time processing successfully, that provides a useful tool for automobile development.

This study aims to examine the effects of climate change and agricultural technologies on crop production in Vietnam for the period 1990–2018.

Several econometric techniques – such as the augmented Dickey–Fuller, Phillips–Perron, the autoregressive distributed lag (ARDL) bounds test, variance decomposition method (VDM) and impulse response function (IRF) are used for the empirical analysis.

The results of the ARDL bounds test confirm the significant dynamic relationship among the variables under consideration, with a significance level of 1%. The primary findings indicate that the average annual temperature exerts a negative influence on crop yield, both in the short term and in the long term. The utilization of fertilizer has been found to augment crop productivity, whereas the application of pesticides has demonstrated the potential to raise crop production in the short term. Moreover, both the expansion of cultivated land and the utilization of energy resources have played significant roles in enhancing agricultural output across both in the short term and in the long term. Furthermore, the robustness outcomes also validate the statistical importance of the factors examined in the context of Vietnam.

This study provides persuasive evidence for policymakers to emphasize advancements in intensive agriculture as a means to mitigate the impacts of climate change. In the research, the authors use average annual temperature as a surrogate measure for climate change, while using fertilizer and pesticide usage as surrogate indicators for agricultural technologies. Future research can concentrate on the impact of ICT, climate change (specifically pertaining to maximum temperature, minimum temperature and precipitation), and agricultural technological improvements that have an impact on cereal production.

To the best of the authors’ knowledge, this study is the first to examine how climate change and technology effect crop output in Vietnam from 1990 to 2018. Various econometrics tools, such as ARDL modeling, VDM and IRF, are used for estimation.