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The purpose of this paper is to discriminate fake interference caused by polygonal approximation so as to achieve accurate assembly sequence planning and assembly simulation.

An approximation zone model is proposed to formulate polygonal approximation. Fake interference is discriminated from hard interference by evaluating if polygonal models intersect within corresponding approximation zones. To reduce the computation, the surface-surface, surface-end face and end face-end face intersection test methods have been developed to evaluate the intersection and obtain collision data. An updated collision detection algorithm with this method is presented, which is implemented by a system named AutoAssem.

This method has been applied to a set of products such as a valve for assembly interference matrix generation, static and dynamic collision detection. The results show that it ensures the accuracy of assembly sequence planning and assembly simulation for polygonal models.

This method facilitates assembly design in the virtual environment with polygonal models. It can also be applied to computer aided design systems to achieve quick and accurate collision detection.

Fake interference between polygonal models may result in serious errors in assembly sequence planning and assembly simulation. Assembly zone model and novel polygon intersection verification methods have been proposed to effectively tackle this problem. Compared to current methods, this method considers valid penetration direction and approximation difference, does not need to process complicated auxiliary data and can be easily integrated with current collision detection methods.

This study aims to investigate the noise-inducing characteristics during the start-up process of a mixed-flow pump and the impact of different start-up schemes on pump noise.

This study conducted numerical simulations on the mixed-flow pump under different start-up schemes and investigated the flow characteristics and noise distribution under these schemes.

The results reveal that the dipole noise is mainly caused by pressure fluctuations, while the quadrupole noise is mainly generated by the generation, development and breakdown of vortices. Additionally, the noise evolution characteristics during the start-up process of the mixed-flow pump can be divided into the initial stage, stable growth stage, impulse stage and stable operation stage.

The findings of this study can provide a theoretical basis for the selection of start-up schemes for mixed-flow pumps, reducing flow noise and improving the operational stability of mixed-flow pumps.

For underwater hydraulic machinery, the unique structure significantly enhances the three-dimensional non-uniformity of turbulence within the flow domain and high Reynolds number turbulence introduces complex effects on the machinery. Therefore, studying the turbulent flow characteristics in underwater hydraulic machinery is crucial for system stability.

This paper conducts a numerical analysis on a specific type of underwater hydraulic machinery. A numerical calculation model is established under stable inflow conditions to analyze the flow trends and pressure changes at different flow speeds. Subsequently, structural modifications are made to the underwater hydraulic machinery, and the characteristics of the velocity field, pressure field and vorticity distribution under different model parameters are analyzed.

The results indicate that changes in internal structure have a certain impact on flow characteristics. When the structural changes are significant, the fluid flow becomes more complex and pressure fluctuations become more intense. The research findings provide a scientific basis and theoretical guidance for the structural design of underwater hydraulic machinery and have significant research implications for controlling fluid-induced noise.

Affected by the inherent structural characteristics of the flow channel structure, the flow direction of the high-speed water flow changes drastically in the flow channel, so it is of great significance to study its flow characteristics for the stability of the system.

In this paper, wool fibers are modified with titanate tetrabutyl by coating and grafting titanium dioxide (TiO₂) nanoparticles under low temperature hydrothermal conditions. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis and diffuse reflectance spectroscopy are used as the characterization techniques. It is found that anatase TiO₂ nanocrystals with crystal sizes smaller than 10 nm can be synthesized and simultaneously grafted onto fiber surfaces. In comparison with pristine wool fibers, the thermal stability for the TiO₂-coated wool fibers is slightly changed. The ability to block ultraviolet radiation is improved. The volume density is slightly increased. The tensile properties are enhanced, while the crimp properties worsened. A photocatalytic degradation process of methylene blue dye and a decoloration rocess of chlorophyll are developed.

This paper aims to provide SIF calculation method for engineering application.

In this paper, the stress intensity factors (SIFs) calculation method is applied to the anisotropic Ni-based single crystal film cooling holes (FCHs) structure.

Based on contour integral, the anisotropic SIFs analysis finite element method (FEM) in Ni-based single crystal is proposed. The applicability and mesh independence of the method is assessed by comparing the calculated SIFs using mode of plate with an edge crack. Anisotropic SIFs can be calculated with excellent accuracy using the finite element contour integral approach. Then, the effect of crystal orientation and FCHs interference on the anisotropic SIFs is clarified. The SIFs of FCH edge crack in the [011] orientated Ni-based single crystal increases faster than the other two orientations. And the SIF of horizontal interference FCHs edge crack is also larger than that of the inclined interference one.

The SIFs of the FCH edge crack in the turbine air-cooled blade are innovatively computed using the sub-model method. Both the Mode I and II SIFs of FCHs edge crack in blade increase with crack growing.

The purpose of this study is to describe the mechanism of single-crystal high-temperature creep deformation, predict the creep life more accurately and study the creep constitutive and lifetime models with microstructure evolution.

The mechanical properties of nickel-based single-crystal superalloy are closely related to the γ' phase. Creep tests under four different temperature and stress conditions were carried out. The relationship between creep temperature, stress and life is fitted by numerical method, and the creep activation energy is obtained. The creep fracture surface, morphology and evolution of strengthening phase (γ') and matrix phase (γ) during different creep periods were observed by scanning electron microscope. With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by transmission electron microscope (TEM).

With the increase of creep temperature, the rafting time is advanced. The detailed morphology and evolution of dislocations were observed by TEM. Dislocations are mainly concentrated in the γ channel phase, especially at high temperature and low stress.

A creep constitutive model based on the evolution of γ' phase size and γ channel width was proposed. Compared with the experimental results, the predicted creep life is within 1.4 times error dispersion band.

Based on the investigation of large length measurement and alignment techniques in 3D construction, a laser diode alignment system for boat assembly is presented. In the system, a horizontal laser diode beam and a vertical light plane formed by a rotating pentagonal prism are used as a measuring datum. The system is of low cost, reliable, safe and convenient to be used on‐line in small boatyards with reasonable accuracy. The synthesised error of the system is analysed. The application of the system in boat assembly and some considerations of the system design are described.

The purpose of this paper is to introduce a co‐simulation method to study the ground maneuvers of aircraft anti‐skid braking and steering.

A virtual prototype of aircraft is established in the multibody system dynamics software MSC.ADAMS/Aircraft. The anti‐skid braking control model, which adopts the multi‐threshold PID control method with a slip‐velocity‐controlled, pressure‐bias‐modulated (PBM) system, is established in MATLAB/Simulink. EASY5 is used to establish the hydraulic system of nose wheel steering. The ADAMS model is connected to block diagrams of the anti‐skid braking control model in MATLAB/Simulink, and is also connected to the block diagrams of nose wheel steering system model in EASY5, so that the ground maneuvers of aircraft anti‐skid braking and steering are simulated separately.

Results are presented to investigate the performance of anti‐skid braking system in aircraft anti‐skid simulation. In aircraft steering simulation, the influence of two important parameters on the forces acting on the tires is discussed in detail, and the safe area to prevent aircraft sideslip is obtained.

This paper presents an advanced method to study the ground maneuvers of aircraft anti‐skid braking and steering, and establishes an integrated aircraft model of airframe, landing gear, steering system, and anti‐skid braking system to investigate the interaction of each subsystem via simulation.

While many stepped spillways geometry design guidelines were developed for flat steps, designing pooled steps might be an appropriate alternative to spillways working more efficiency. This paper aims to deal with the inception point of air-entrainment and void fraction in the different height of the pools. Following that, pressure distribution was evaluated in aerated and non-aerated regions under the effect of different heights of the pools and slopes through the use of the FLOW-3D software. Comparison of obtained numerical results with experimental ones was in good agreement for all discharges used in this study. Pools height had the insignificant effect on the inception point location. The value of void fraction was more affected in lower discharges in comparison with higher ones. Negative pressure was not seen over the crest of spillway (non-aerated region), and the maximum pressure values were obtained for pools with 15 cm height along the crest in each discharge. In all slopes, negative pressure was not formed near the step bed in the pooled and flat stepped spillways. However, negative pressure was formed in more area near the vertical face in the flat stepped spillway compared with the pooled stepped spillway which increases the probability of cavitation phenomenon in the flat stepped chute.

A pooled stepped spillway was used in order to evaluate pressure, void fraction, and inception point. Also, different height of the pools was used. Numerical simulation of this study was fulfilled through Flow-3D software. The obtained results indicated that pools can affect two-phase flow characteristics including pressure, void fraction and inception point.

Over the crest, negative pressure was not seen. Pressure values were different for all used heights and the maximum ones obtained for 15 cm height. Also, pooled stepped played a more effective role in reducing the negative pressure points compared with flat cases. Inception point location was more affected in nappe and transition flow regimes in comparison with skimming flow regime particularly for 9 and 15 cm heights.

The research results of Felder et al. (2012a) from the University of Queensland were used to numerically simulate the flow over the pooled stepped spillway.

This study aims to analyze a novel phenomenon observed in recent years regarding the internationalization strategies of Chinese mobile internet e-commerce platform companies, which could extend traditional internationalization theories based on the experiences of companies from developed countries and traditional Chinese industries.

The traditional Uppsala model and imitation learning model of firm internationalization theory do not fully explain the motivations and behaviors behind new market entry in the internationalization practices of Chinese mobile internet companies. This study begins with the new internationalization practices of Pinduoduo, the fastest-growing mobile e-commerce platform in China, with the growth desperation theory as a perspective. By drawing on grounded theory methods, it explores the motivations and entry modes of internationalization within the broader context of recent Chinese mobile internet companies expanding abroad. This provides a theoretical explanation for traditional internationalization motivation and entry mode theories based on the new phenomenon of Chinese mobile internet platforms. Additionally, using Stata software and event study methodology, the financial performance and stock market performance of Pinduoduo’s new market entry behavior are analyzed.

It posits that when enterprises face pressures related to domestic market growth constraints, they tend to adopt strategic decisions for new market entry to alleviate growth pressures based on new growth opportunities and platforms. During the process of entering new markets, enterprises tend to adopt the “Copy from China” (CFC) model to efficiently replicate the successful experiences in the Chinese market. Market selection for new entries is determined based on psychological distance.

First, the case study provides valuable insights for other mobile internet platforms, but these insights may not be directly transferable to companies in traditional industries; second, directly replicating well-developed business operations and marketing models from the Chinese market to new global markets might face cultural adaptability issues. How could firms balance the general principles of the Chinese internet model with the unique contexts of different global markets will be a crucial focus for future research.

Pinduoduo’s new market entry strategy represents a microcosm of Chinese mobile internet e-commerce platform enterprises’ international expansion choices, reflecting a significant phenomenon and future trend in Chinese business practices. Against the backdrop of widespread growth bottlenecks in current Chinese mobile internet e-commerce platform companies, adopting the CFC model to explore overseas markets in the future presents an opportunity for companies to expand new growth platforms, offering insights for current business practices.

This paper attempts to construct a new theoretical explanation for internationalization with unique characteristics of the Chinese mobile internet industry, based on the integration of “internationalization theories – internationalization practice – comprehensive research methods.” The study enriches strategic literature on the factors influencing new market entry for Chinese mobile internet e-commerce platform companies by exploring how increased growth pressures affect their strategic decisions to enter new markets. Meanwhile, it reveals a new market-entry-mode, the CFC (Copy from China) model, which reflects current trends in the practices of Chinese mobile internet e-commerce platform companies, providing practical insights for the international expansion activities of mobile internet companies in other industries.