Search results

Due to the structural layout, mining process, and working environment, curved chains such as horizontal and vertical bends inevitably exist in the armoured face conveyor (AFC). With the increasing power, conveying capacity, and distance of the AFC, the dynamic influence of these curved chains should be highly emphasized. This paper establishes a dynamic model of the AFC by multi-body system theory and finite segment method, in which the curved chains can be fully considered.

The scraper chains are firstly grouped into the straight, horizontal bend, vertical convex and concave bend sections. Each bend section running in a circle is simplified as an ideal arc. Through solving its differential equilibrium equation and using Newton's second law, its running resistance is derived. Then the grouped chains are discretized into finite control elements according to the Kelvin model, and the governing equation of each control element is established. The dynamic model of the AFC is obtained by assembling these equations, and the corresponding simulation model is developed by using MATLAB/Simulink.

Case studies with real scenarios are provided, and simulations are carried out. The results show that the running resistance contributed by the curved chains is larger than the traditional empirical value.

The work in this paper helps the dynamic performance design of AFC, with a deep understanding of the curved chains.

The use of removable complete dentures is a selectable restorative procedure for edentulous patients. To improve the fabrication quality and efficiency of removable complete dentures, this paper aims to introduce a new method to fabricate customized wax complete dentures with additive manufacturing. This process uses complementary digital technologies, and allows faster and better manufacture of complete dentures.

In the study, a dental scanner was used to obtain surface data from edentulous casts and rims made by the dentist. A parameterized three-dimensional graphic database of artificial teeth was pre-established. Specialized computer-aided design software was used to set up the artificial dentition and design the esthetic gingiva and base plate. A selective laser sintering machine was used to transfer the data from stereolithography files into a wax base plate with location holes for each artificial tooth.

Under this method, a set of wax base plates with 28 location holes available for the placement of the artificial teeth were designed and fabricated within 6 h. The try-in wax dentures fitted the patient’s mouth well, besides occlusion relationships. Then, the occlusion relationships can be adjusted manually to achieve a balanced centric occlusion.

This method can be used to design and fabricate wax try-in removable complete dentures semi-automatically and rapidly; however, the algorithm for the occlusion contact design needs to be improved.

The purposes of this paper are to analyze the path and speed of rural transformation (RT) and explore the relationship between farmer's income and RT as well as structural transformation (ST) and typology of RT in the past four decades in China.

Based on the major indicators of RT and ST, graphic illustration is used to analyze the relationships between these indicators and farmer's income using the time-series and cross-provincial data in 1978–2017.

While China has experienced significant RT and ST, the levels and speeds of these transformations differed largely among provinces. Higher and faster RT and ST are often positively associated with the higher and faster growth of rural income. Based on this study, a general typology of rural and structural transformations and rural income is developed. The likely impacts of institutions, policies and investments (IPIs) on RT are discussed.

The authors believe that the findings of this study provide the insights on regional RT and ST and policy implications to increase farmer's income through facilitating and speeding up RT and ST with appropriate IPIs during the rural transformation.

The purpose of this paper is to identify electronic word-of-mouth (eWOM) customers from customer reviews. Thus, firms can precisely leverage eWOM customers to increase their product sales.

This research proposed a framework to analyze the content of consumer-generated product reviews. Specific algorithms were used to identify potential eWOM reviewers, and then an evaluation method was used to validate the relationship between product sales and the eWOM reviewers identified by the authors’ proposed method.

The results corroborate that online product reviews that are made by the eWOM customers identified by the authors’ proposed method are more related to product sales than customer reviews that are made by non-eWOM customers and that the predictive power of the reviews generated by eWOM customers are significantly higher than the reviews generated by non-eWOM customers.

The proposed method is useful in the data set, which is based on one type of products. However, for other products, the validity must be tested. Previous eWOM customers may have no significant influence on product sales in the future. Therefore, the proposed method should be tested in the new market environment.

By combining the method with the previous customer segmentation method, a new framework of customer segmentation is proposed to help firms understand customers’ value specifically.

This study is the first to identify eWOM customers from online reviews and to evaluate the relationship between reviewers and product sales.

The purpose of this study is to explore the three-way interaction effects among congruence type (proximal vs distal) of nonverbal ad messages, assessment perspective (internal vs external) of verbal ad messages and social distance (close vs faraway) on consumers’ visit intention.

After developing the four categories of restaurant advertisements and scenarios for each type of social distance, the authors used 780 observations collected from Chinese consumers via the online survey platform Sojump and WeChat. The authors conducted ANOVA to test the hypotheses.

The results reveal that in proximal congruence situations, consumers who feel a close social distance between themselves and their companions report higher visit intentions when exposed to internal versus external perspective-oriented ad messages; in distal congruence situations, external perspective-oriented ad messages elicit higher intention to visit advertised restaurant when consumers feel a far social distance between themselves and their companions.

Future research can focus on the different categories of messages, such as functional and experiential messages, to find whether similar interaction effects are explored or not.

This paper suggests some practical implications for advertisers to maximize the impact of advertisements on consumers’ behavioral outcomes via combining the different characteristics of nonverbal and verbal messages effectively, especially according to their target consumers’ characteristics.

In the view of the three-way interaction effects, this paper offers a new lens on understanding how advertisements influence consumers’ behavioral outcomes, which could contribute to the advancement of advertisement theories.

Simulation is a well-known technique for using computers to imitate or simulate the operations of various kinds of real-world facilities or processes. The facility or process of interest is usually called a system, and to study it scientifically, we often have to make a set of assumptions about how it works. These assumptions, which usually take the form of mathematical or logical relationships, constitute a model that is used to gain some understanding of how the corresponding system behaves, and the quality of these understandings essentially depends on the credibility of given assumptions or models, known as VV&A (verification, validation and accreditation). The main purpose of this paper is to present an in-depth theoretical review and analysis for the application of VV&A in large-scale simulations.

After summarizing the VV&A of related research studies, the standards, frameworks, techniques, methods and tools have been discussed according to the characteristics of large-scale simulations (such as crowd network simulations).

The contributions of this paper will be useful for both academics and practitioners for formulating VV&A in large-scale simulations (such as crowd network simulations).

This paper will help researchers to provide support of a recommendation for formulating VV&A in large-scale simulations (such as crowd network simulations).

The purpose of this paper is to identify the energy absorption characteristics of arch micro-strut (ARCH) lattice structure (different from traditional straight micro-strut lattice structure) under high-speed impact, and promote the development of special-shaped micro-strut lattice structure.

The study serves to study the anti-impact and energy absorption characteristics of ARCH lattice structure under different strain rates and different unit layers of lattice structure. In this paper, quasi-static compression and Hopkinson compression bar experiments are used for comparative analysis.

The results show that the ARCH lattice structure has obvious strain rate effect. When the strain rate is low, the number of layers of lattice structure has a great influence on the mechanical properties. With the increase of strain rate, the influence of the number of layers on the mechanical properties gradually weakens. So the ARCH lattice structure with fewer layers (less than five layers) should be selected as the impact energy absorbing materials at lower impact rate, while at higher impact rate, the number of layers can be selected according to the actual requirements of components or devices space size.

This study shows that Arch lattice structure has excellent energy absorption performance, and provides a theoretical reference for the application of ARCH lattice structure in energy-absorbing materials. ARCH lattice structure is expected to be applied to a variety of energy absorption and anti-impact components or devices, such as aircraft black box fall buffer components, impact resistant layer of bulletproof and landing buffer device.

The impact of network centrality on innovation performance is inconclusive. The purpose of this paper is to examine how formal and informal institutions affect the influence of network centrality on firms’ innovation performance in emerging economies by integrating social network theory and institutional theory.

Multisource and lagged data from 234 technology-based entrepreneurial firms listed on the Chinese Growth Enterprise Market were leveraged to test a proposed research model.

Results suggest that formal institutions (marketization) positively moderate the relationship between network centrality and innovation performance, whereas informal institutions (social cohesion) negatively moderate this relationship. Moreover, formal and informal institutions have a strong joint impact on such relationship, that is, the effect of network centrality on innovation performance is most positive when marketization is high and social cohesion is low.

This empirical research provides new insights into whether and how firms can grasp the innovation benefits of network centrality by exploring institutional contingencies. It further sheds on light the scope of the network centrality–innovation issue by extending its research context to Chinese entrepreneurial firms.

The purpose of this paper is to examine the difference of credit enhancement of variously secured bonds issued by local government financing platform bond (LGFPB).

The approaches to secure the bonds usually include mortgage, collateral, guarantee, etc.

Using a sample of LGFPBs issued during the 2007-2013 period, the authors find that all of the approaches to secure the bonds would increase the bond rating and that compounded approaches have a higher credit enhancement effect than single approaches. Among these approaches, the requirement of collateral has the strongest enhancement effect. Moreover, the authors find that the guarantee provided by a state-owned bank or enterprise increases the bond rating more than the guarantee provided by other local government financing platforms.

The findings in this study suggest that the credit enhancement would be deeply affected by the approach used to secure the bond.

These results can help the local government make better decisions when issuing bond.

This study empirically analyzes the different credit enhancement approaches for securing LGPFBs for the first time and contributes to the literature regarding credit ratings of local government bonds.

This study aims to analyze the relevance of the city spatial structure for smart city innovation from the perspective of agglomeration externalities, and discusses whether there is heterogeneity in innovation across different geographical areas and population scales of cities.

The authors construct the centralization and concentration indexes to conceptualize the city spatial structure of 286 cities (prefecture-level) in China based on the LandScan Global Population Dataset from 2001 to 2016. A fixed-effects panel data model is employed to analyze the relationship between the spatial structure and the innovation ability of smart cities; the results were validated through robustness tests and heterogeneity analyses.

The study found that the more concentrated and more evenly the distribution of urban population, namely the more city spatial structure tends to be weak-monocentricity, the higher the level of innovation in smart cities. The relevance of the weak-monocentricity structure and smart city innovation varies significantly depending on their geographical location and the size of the city. This result is more applicable to cities in the eastern and central regions, as well as to cities with smaller populations.

The adjustment and optimization of the city spatial structure is important for enhancing smart city construction. Unlike previous studies, which mostly use a single dimension of “the proportion of population in sub-centres to the population of all central areas” to measure city spatial structure, the authors employed the spatial centralization and spatial concentration. It is hoped that this study can guide smart city construction from the perspective of the development model of city spatial structure.