Search results

As for vibrating screen, the separation of granular materials is a very complicated process, particularly the screening with a swing trace. To study the characteristics of stratification and penetration in the swing vibrating screen, a three-dimensional numerical model was developed to simulate the screening process.

The discrete element method (DEM) was used to perform the numerical simulation, and the kinetic model of the swing screening was established. The regions of stratification and penetration were defined, and the mathematical functions relating fine particle ratio of stratification and penetration to time were presented using the least squares method.

The results show that the low value of frequency (5 and 10 Hz) has a limited effect on the stratification, while the obvious effect can be found at high frequency. A low frequencies or small swing angles may enhance the particle penetration. By studying the vibration parameters affecting the stratification and penetration rate, it is found that the frequency has more influence than the swing angle.

The higher screening efficiency and processing capacity can be further obtained for the swing vibrating screen by comparing with the linear vibrating screen. These results reveal the fundamental characteristics of particle motion in the swing screening, which will provide reliable guidance for studying the design optimization of vibrating screen.

This paper aims to avoid the precise modeling and controlling problems of rigid structures of hand recovery device, by proposing a hand rehabilitator based on flexible pneumatic actuator with its safety and adaptability.

The hand rehabilitator is designed based on a flexible pneumatic bending joint. The recovery training program for an injured finger is developed via forearm sEMG (surface electromyogram) sampling, analysis, classification and motion consciousness identification. Four typical movement models of the index finger and middle finger were defined and the corresponding sEMG signals were sampled. After simulation and comparative analysis, autoregressive (AR) model back propagation (BP) network was selected for sEMG analysis and hand recovery planning because of its best recognition performance. A verification test was designed and the results showed that the soft hand rehabilitator and recovery conception are feasible.

AR model BP network can identify the index finger and middle finger movement intention via an sEMG analysis. The developed flexible pneumatic hand rehabilitator is safe and suitable for finger recovering therapy.

Because of the limitation of experimental samples, the prototype rehabilitator of this work may lack generalizability for other situations. Therefore, for further study and application, systematic structure revising, experiments, data and training are necessary to improve the performance.

The paper includes implications for the development and application of a new style, safe and dexterous hand rehabilitator.

The paper tries a new approach to design a safe, flexible and easily controlled hand rehabilitator.

With the continuous deepening of China's mixed-ownership reform, the participants in the reform have gradually expanded from state-owned enterprises to private enterprises. Whether state-owned equity participation in private enterprises can facilitate the development of environmental, social and governance (ESG) performance in private enterprises is a question that needs urgent examination. This study aims to investigate the impact of state-owned equity participation on the ESG performance of private enterprises.

Using Chinese listed companies as the research sample, this study uses econometric methods such as multiple regression to analyze the relationship between state-owned equity and the ESG performance of private enterprises. Additionally, it explores the underlying mechanisms and influencing factors of this relationship.

There is a significant inverted U-shaped relationship between state-owned equity and the ESG performance of private enterprises. Mechanism analysis reveals that resource effects and governance effects play a mediating role in this nonlinear relationship. Furthermore, the authors find that environmental regulation and managers' attention to the environment positively moderate the relationship between state-owned equity participation and ESG performance.

A reasonable equity structure is crucial for enhancing corporate ESG performance. Moderate state-owned equity participation helps to leverage resource integration and governance advantages, which will assist private enterprises in maximizing ESG performance and achieving sustainable development.

In advancing the process of mixed-ownership reform, the government should maintain an appropriate proportion of state-owned equity to avoid excessive intervention in enterprise decision-making. At the same time, it should ensure that enterprises can genuinely undertake their social and environmental responsibilities while pursuing economic benefits. This is of great significance for promoting sustainable economic and social development.

This study integrates state-owned equity, ESG and nonlinear relationships into a single research framework. It explores the internal mechanisms and influencing factors of their relationship, overcoming the limitations of previous studies and provides a new perspective for understanding the impact of state-owned equity on corporate ESG performance.

The purpose of this study was to investigate the tribological properties of bulk Fe₂B with pre-oxidation treatment.

Bulk Fe₂B was oxidized in an electric box furnace with a soaking time of 9 min under 750°C in air. Then, the tribological experiments were carried out on an UMT-Tribolab tester.

The oxide layer was composed of Fe, Fe₂O₃, Fe₃O₄, B₂O₃ and H₃BO₃. The oxidative direction of bulk Fe₂B was perpendicular to the sample surface. But, the oxidative direction of Fe₂B crystals was irregular. At 0.1 m/s, the friction coefficient was the lowest. The effects of shortening the running-in period of friction and reducing the friction coefficient by pre-oxidation treatment at 0.1 m/s were remarkable. Nevertheless, the effect of pre-oxidation treatment was futile at 0.2 m/s. Wear mechanisms of oxidized Fe₂B mainly were adhesive and abrasive wear.

The effects of shortening the running-in period of friction and reducing the friction coefficient by pre-oxidation treatment were remarkable.

To enrich the research on the economic consequences of enterprise digital development from the perspective of capacity utilization.

Using a sample of listed firms from 2010 to 2020, this paper exploits text analysis of annual reports to construct a proxy for enterprise digital development.

Results show that enterprise digital development not only improves their own capacity utilization but also generates a positive spillover effect on the capacity utilization of peer firms and firms in the supply chain. Next, based on the incomplete information about market demand and potential competitors when making capacity-building decisions, the mechanism tests show that improving the accuracy of market forecasts and reducing investment surges are potential channels behind the baseline results. Cross-sectional tests show the baseline result is more pronounced when industries are highly homogeneous and when firms have access to less information.

This paper contributes to the research related to the economic consequences of digital development. With the development of the digital economy, the real effects of enterprise digital development have also triggered extensive interest and exploration. Existing studies mainly examine the impact on physical operations, such as specialization division of labor, innovation activities, business performance or total factor productivity (Huang, Yu, & Zhang, 2019; Yuan, Xiao, Geng, & Sheng, 2021; Wang, Kuang, & Shao, 2017; Li, Liu, & Shao, 2021; Zhao, Wang, & Li, 2021). These studies measure the economic benefits from the perspective of the supply (output) side but neglect the importance of the supply system to adapt to the actual market demand. In contrast, this paper focuses on capacity utilization, aimed at estimating the net economic effect of digital development by considering the supply-demand fit scenario. Thus, our findings enrich the relevant studies on the potential consequences of digital development.

The purpose of this paper is to build a link between empowering leadership and change-oriented organizational citizenship behavior (OCB) based on the theory of the socially embedded model so as to explore why empowering leadership has an impact on change-oriented OCBs and for whom this effect may be amplified or alleviated.

Using data collected from 203 employees and 80 supervisors in one information technology company, the authors examined the mediating role of thriving at work and the moderating role of autonomy between empowering leadership and change-oriented OCBs. The authors used statistical methods such as hierarchical regression, bootstrapping test, and so on to analyze the data.

The results indicated that empowering leadership was positively related to thriving at work, and thus in turn influenced change-oriented OCBs. In addition, employees’ autonomy orientation moderated those relationships such that when employees were had high autonomy orientations, they thrived at work to a high degree and were more likely to perform change-oriented OCBs.

The authors collected the data of this study within a single organization, and that may limit the observed viability and decrease external validity.

The findings suggest that leaders’ empowering behaviors are a critical factor for simulating employees’ change-oriented OCBs. They also indicate that leaders are better off empowering individuals with high autonomy orientations.

This study contributes to the literature by linking empowering leadership and change-oriented OCBs. It clarifies how and why empowering leadership can stimulate employees’ change-oriented OCBs.

Building Information Modeling (BIM) capabilities have been studied at the individual, project, organizational, and even industry levels to ensure the realization of BIM value in the architectural, engineering, construction, and operation industry. However, limited research has focused on a project owner organization perspective to investigate owner BIM capabilities that are required to ensure effective project management and delivery. This present study aims to propose an indicator framework to evaluate owner BIM capabilities at the organizational level.

Leveraging the existing literature on BIM capabilities and synthesizing insights from the resource-based view and information technology capabilities research, this study conceptualizes the BIM capabilities of project owner organizations and offers a framework of indicators for measurement. Semi-structured interviews with BIM experts and a questionnaire survey were conducted to identify key indicators affecting owner BIM capabilities. A six-dimensional structural equation model with 29 indicators was then established.

The findings highlight the multidimensionality of owner BIM capabilities and show that process capabilities play a crucial role in enhancing owner BIM capabilities, while technical capabilities are considered as the least important aspect.

The study sheds light on the key role of project owner organizations in ensuring BIM value and suggests that project owners focus more on the organizational processes of introducing BIM in managing projects.

This study reconceptualizes owner BIM capabilities drawing on the idea of resource-based view and information technology capabilities and highlights the important dimensions and indicators of owner BIM capabilities at the organizational level.

The purpose of this paper is to develop a novel integrated risk assessment method from the system perspective to evaluate the risk of the cross-regional mega construction project (CMCP). Furthermore, this paper aims to confirm the core risk source factors and refine the risk management strategies of CMCPs through a case study.

Based on the analysis of the risk system of CMCPs, the concept model and risk assessment principles of integrated risk assessment were confirmed. The risk source factors and project objectives of the CMCP were identified from a literature review, export interview and case analysis. According to the vulnerability theory, the integrated risk assessment model was developed by involving vulnerabilities, threats, objectives and interaction of those factors synthetically. Then, ZW high-speed railway from China was analyzed to verify the feasibility and effectiveness of the proposed method.

As a result, 12 threat factors and 12 vulnerability factors were identified. Based on the case study, the main external threat comes from T13 (conflicts of interest between local governments) and T23 (harsh natural environment); the most easily exploited internal vulnerabilities were V11 (complexity of technology), V13 (lack of experience in technical application), V21 (inadequate experience) and V23 (lack of interest coordination mechanism). Moreover, the economic objective was most affected.

It is essential to develop an interest coordination mechanism for CMCPs. The harsh natural environment is a critical factor, but it also promotes technological innovation and iteration. Public opinions in different regions are critical for CMCPs, and more emphasis should be placed on public opinion surveys of CMCPs. Moreover, diverse and flexible environmental protection strategies should apply in CMCPs.

This research has the following three contributions. First, based on vulnerability theory, an integrated risk assessment approach of CMCPs is developed, which enriches the risk measurement method system and provides inspiration for future research on risk in the construction industry. Second, the risk sources of CMCPs are identified from the perspective of vulnerability and threat to provide clear guidance for the risk management of CMCPs. Third, the core risk source factors and management strategies confirmed by the case study will be beneficial for various governments in different regions and project managers to optimize the project management scheme, as they are transferable management experiences.

Considering the external disturbances and dynamic uncertainties during the process of the trajectory tracking, this paper aims to address the problem of the welding robot trajectory tracking with guaranteed accuracy.

The controller consists sliding mode control, fuzzy control and low pass filter. The controller adopts low-pass filter to reduce the high frequency chattering control signal in sliding mode control. The fuzzy control model is used to simulate the external disturbance signal and the dynamic uncertainty signal, so that the controller can effectively restrain the chattering caused by the sliding mode control algorithm, realizing the track of the welding robot effectively and improving the robustness of the robot.

An innovative experiment device was adopted to realize the performance of the proposed controller. Considering the kinematic and dynamic uncertainty during the process of robot tracking, the tracking accuracy was realized within 0.3 mm.

This paper uses Lyapunov stability theory and Barbalat theorem to analyze the stability of the proposed controller.

The purpose of this paper is to propose a DC-port voltage balance strategy realizing it by logic combination modulation (LCM). This voltage balance strategy is brief and high efficient, which can be used in many power electronic devices adopting the cascaded H-bridge rectifier (CHBR) such as power electronic transformer (PET).

The CHBR is typically as a core component in the power electronic devices to implement the voltage or current conversion. The modulation method presented here is aiming to solve the voltage imbalance problem occurred in the CHBR with more stable work station and higher reliability in ordinary operating conditions. In particular, by changing the switch states smoothly and quickly, the DC-port voltage can be controlled as the ideal value even one of the modules in CHBR is facing the load-removed problem.

By using the voltage balance strategy of LCM, the problem of voltage imbalance occurring in three-phase cascaded rectifiers has been solved properly. With the lower modulation depth, the efficiency of the strategy is shown to be better and stronger. The strategy can work reliably and quickly no matter facing the problem as load-removed change or the ordinary operating conditions.

The limitation of the proposed DC-port voltage balance strategy is calculated and proved, in a three-module CHBR, the LCM could balance the DC-port voltage while one module facing the load-removed situation under 0.83 modulation depth.

This paper provides a useful and particular voltage balance strategy which can be used in the topology of three-phase cascaded rectifier. The value of the strategy is that a brief and reliable voltage balance method in the power electronic devices can be achieved. What is more, facing the problem, such as load-removed, in outport, the strategy can response quickly with no switch jump and switch frequency rising.