Search results

Walking on inclined ground is an important ability for humanoid robots. In general, conventional strategies for walking on slopes lack technical analysis in, first, the waist posture with respect to actual robot and, second, the landing impact, which weakens the walking stability. The purpose of this paper is to propose a generic method for walking pattern generation considering these issues with the aim of enabling humanoid robot to walk dynamically on a slope.

First, a virtual ground method (VGM) is proposed to give a continuous and intuitive zero-moment point (ZMP) on slopes. Then, the dynamic motion equations are derived based on 2D and 3D models, respectively, by using VGM. Furthermore, the waist posture with respect to the actual robot is analyzed. Finally, a reformative linear inverted pendulum (LIP) named the asymmetric linear inverted pendulum (ALIP) is proposed to achieve stable and dynamical walking in any direction on a slope with lower landing impact.

Simulations and experiments are carried out using the DRC-XT humanoid robot platform with the aim of verifying the validity and feasibility of these new methods. ALIP with consideration of waist posture is practical in extending the ability of walking on slopes for humanoid robots.

A generic method called ALIP for humanoid robots walking on slopes is proposed. ALIP is based on LIP and several changes, including model analysis, motion equations and ZMP functions, are discussed.

The purpose of this study is to analyze the short-term development pattern and long-term development trend of the digital supply chain.

This study uses the combination of short-term game and long-term evolutionary game theory.

Findings of this study suggest that irrational decisions can make the evolutionary path of the digital supply chain complex and unpredictable.

This study proposes an evolutionary game model for the digital supply chain that can provide good guidance for the digitalization process of enterprises.

To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.

In this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.

The recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.

For the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.

This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on the additional single pile responses in terms of bending moment, lateral deflection, axial force, shaft resistance and pile settlement. Subsequently, a series of parametric studies were carried out to better understand the responses of single piles induced by tunneling. To give further understanding regarding the pile groups, a 2 × 2 pile group with two different pile head conditions, namely, free and capped, was considered.

Using the PLAXIS three-dimensional (3D) software, a full 3D numerical modeling is performed to investigate the effects of ground movements caused by tunneling on adjacent pile foundations. The numerical model was validated using centrifuge test data found in the literature. The relevance of the 3D model is also judged by comparison with the 2D plane strain model using the PLAXIS 2D code.

The numerical test results reveal that tunneling induces significant displacements and internal forces in nearby piles. The magnitude and distribution of internal forces depend mainly on the position of the pile toe relative to the tunnel depth and the distance between the pile and the vertical axis of the tunnel. As the volume loss increases from 1% to 3%, the apparent loss of pile capacity increases from 11% to 20%. By increasing the pile length from 0.5 to 1.5 times, the tunnel depth, the maximum pile settlement and lateral deflection decrease by about 63% and 18%, respectively. On the other hand, the maximum bending moment and axial load increase by about 7 and 13 times, respectively. When the pile is located at a distance of 2.5 times the tunnel diameter (Dt), the additional pile responses become insignificant. It was found that an increase in tunnel depth from 1.5Dt to 2.5Dt (with a pile length of 3Dt) increases the maximum lateral deflection by about 420%. Regarding the interaction between tunneling and group of piles, a positive group effect was observed with a significant reduction of the internal forces in rear piles. The maximum bending moment of the front piles was found to be higher than that of the rear piles by about 47%.

Soil is a complex material that shows differently in primary loading, unloading and reloading with stress-dependent stiffness. This general behavior was not possibly being accounted for in simple elastic perfectly plastic Mohr–Coulomb model which is often used to predict the behavior of soils. Thus, in the present study, the more advanced hardening soil model with small-strain stiffness (HSsmall) is used to model the non-linear stress–strain soil behavior. Moreover, unlike previous studies THAT are usually based on the assumption that the soil is homogeneous and using numerical methods by decoupled loadings under plane strain conditions; in this study, the pile responses have been exhaustively investigated in a two-layered soil system using a fully coupled 3D numerical analysis that takes into account the real interactions between tunneling and pile foundations. The paper presents a distinctive set of findings and insights that provide valuable guidance for the design and construction of shield tunnels passing through pile foundations.

This paper reviews the pros and cons of different parametric modeling methods, which can provide a theoretical reference for parametric reconstruction of 3D human body models for virtual fitting.

In this study, we briefly analyze the mainstream datasets of models of the human body used in the area to provide a foundation for parametric methods of such reconstruction. We then analyze and compare parametric methods of reconstruction based on their use of the following forms of input data: point cloud data, image contours, sizes of features and points representing the joints. Finally, we summarize the advantages and problems of each method as well as the current challenges to the use of parametric modeling in virtual fitting and the opportunities provided by it.

Considering the aspects of integrity and accurate of representations of the shape and posture of the body, and the efficiency of the calculation of the requisite parameters, the reconstruction method of human body by integrating orthogonal image contour morphological features, multifeature size constraints and joint point positioning can better represent human body shape, posture and personalized feature size and has higher research value.

This article obtains a research thinking for reconstructing a 3D model for virtual fitting that is based on three kinds of data, which is helpful for establishing personalized and high-precision human body models.

The purpose of this paper is to report on the stabilization network optimization of internally matched GaN high electron mobility transistors (HEMTs).

The effects of the two stabilization networks on the characteristics of the device are discussed, such as the stability, power gain and output power.

With the optimized stabilization network, the internally matched GaN HEMTs with 16‐mm gate width exhibited good stability and delivers a 46 dBm output power with 6.1 dB power gain under the continuous wave condition at 8 GHz. By using the optimized stabilization network, the package process of the large‐scale microwave power device of GaN HEMTs can be simplified.

This paper provides useful information for the internally matched GaN HEMTs.

Social shopping website (SSW) introduce the social side into the shopping process, thus making “window” shopping or browsing more interesting for customers. The purpose of this paper is to investigate customer online browsing experience and its antecedents (i.e. information quality and social interaction) and consequences (i.e. urge to buy impulsively and continuous browsing intention) in the context of SSW.

A survey questionnaire was distributed to visitors of online SSW to collect data, and partial least squares technology was used to test the research model.

The results of this study reveal that three types of web browsing, namely, utilitarian browsing, hedonic browsing and social browsing, take place in a SSW. The unique factors of SSW, namely, the quality of user generated contents and social interaction are critical for facilitating customers’ browsing experiences. Furthermore, the findings reveal that hedonic browsing experience is found to be the most salient factor influencing customers’ urge to buy impulsively and continuance intention.

The findings suggest that practitioners, such as designers and managers of SSW should give special attention to the benefits of browsing activity to convert web browsers into impulse purchasers and increase customers’ loyalty. Moreover, they should focus on improving the quality of user generated content and pay more attention to support and encourage social interaction to enhance browsing experiences on a SSW.

Existing studies about browsing behavior mostly focus on traditional online e-commerce website. This study represents the first step toward understanding browsing activity on SSW. Moreover, prior studies mainly focused on utilitarian and hedonic browsing experience; however, there is a lack of research on social browsing experience. The current study attempts to fill this research gap.

Due to the vital role of innovation for firms to respond to the change and achieve competitive advantage, the purpose of this study is to investigate the influence of knowledge-oriented leadership (KOL) on innovation performance (IP) via the mediating role of knowledge sharing (KS). This study also clarifies the KS-IP relationship by exploring the moderating role of market turbulence.

Analysis of moment structures and structural equation modeling are applied to examine the relationship among the latent factors in the proposed research model using data collected from 281 participants in 112 manufacturing and service firms in Vietnam.

The findings revealed that KOL serves as a key precursor to foster IP, directly or indirectly, through knowledge-oriented leaders’ effect on tacit and explicit KS behaviors. In addition, the paper highlights the moderating role of market turbulence in strengthening the impact of KS activities on IP.

By highlighting the important role KOL practice for stimulating KS behaviors, this paper provides a valuable understanding and novel approach for firms to improve IP. The research findings support the idea that market turbulence significantly contributes to increasing the effects of KS behaviors on IP.

This study contributes to bridging research gaps in the literature and advances the insights of how KOL directly and indirectly fosters IP via mediating roles of tacit and explicit KS processes under the effects of market turbulence.

Augmented reality (AR) has become a trend, and the effects of Pokémon Go, the most popular online and mobile game, have been explored in many studies. However, few studies have developed questionnaires of fit to investigate the relationship between the fit and the integration of the game's virtual world and reality. The paper intends to integrate the models of stimulus-organism-response (S-O-R) and information systems success with cognitive fit theory to explore the fit and reactions of users in the integration of real and virtual worlds.

Following MacKenzie's scale development, two surveys were conducted. The first survey was conducted to perform a scale development of fit. The second survey was collected from 315 Pokémon Go players to validate the fit scale and it was analyzed via structural equation modeling.

The results show that scale development of fit has good reliability and validity. Furthermore, game information quality, game system quality and virtual (Pokémon) characteristics have significantly positive effects on cognitive and emotional fit. Cognitive and emotional fit have significant positive effects on user satisfaction, and user satisfaction has significant positive effects on continued intention to play. The results suggest that maintaining the quality of the game and improving the virtual interface will provide a better fit between the real and virtual worlds, enhancing user satisfaction with the fit as well as their intention for continued use.

Although fit has been widely studied in various contexts, the application of AR has been rarely discussed. This study develops a scale of fit and takes Pokémon Go as the subject to validate the fit measurement and discuss players' cognition and feelings regarding the game. The authors measure user reactions to different stimuli and explore cognitive and emotional fit as well as the integration of virtual worlds and reality. In sum, to the best of the authors’ knowledge, this is one of the earliest studies to explore and develop a cognitive and emotional fit scale for future researchers and practitioners.

This paper aims to reduce part defects and improve ceramic additive manufacturing (AM). Selective laser melting (SLM) experiments were carried out to explore the effect of laser power and scanning speed on the microstructure, melting behaviour and surface roughness of cuprous oxide (Cu₂O) ceramic.

The experiments were designed based on varying laser power and scanning speed. The laser power was changed between 50 W and 140 W, and the scanning speed was changed between 170 mm/s and 210 mm/s. Other parameters, such as scanning strategy, layer thickness and hatch spacing, remain constant.

Laser power and scan speed are the two important laser parameters of great significance in the SLM technique that directly affect the molten state of ceramic powders. The findings reveal that Cu₂O part defects are widely controlled by gradually increasing the laser power to 110 W and reducing the scanning speed to 170 mm/s. Furthermore, excessive laser power (>120 W) caused surface roughness, cavities and porous microstructure due to the extremely high energy input of the laser beam.

The SLM technique was used to produce Cu₂O ceramic specimens. SLM of oxide ceramic became feasible using a slurry-based approach. The causes of several part defects such as spattering effect, crack initiation and propagation, the formation of porous microstructure, surface roughness and asymmetrical grain growth during the SLM of cuprous oxide (Cu₂O) are thoroughly investigated.