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The purpose of this paper is to reveal the friction and wear performance of grooves textured cylindrical roller thrust bearings with different groove dimensions under starved lubrication.

The groove dimensions include: width of grooves (WOG, 50 µm, 100 µm and 150 µm), depth of grooves (DPOG, 7 µm, 11 µm and 15 µm) as well as groove deflection angle (GDA, 45°). A fiber laser marking system was used to prepare groove patterns on the raceways of shaft washers. The friction and wear properties of grooves textured bearings were researched through a vertical universal wear test rig using a customized roller bearing tribo-pair under starved lubrication. Static finite element analyses were conducted to reveal their surface stresses. Through the comprehensive comparison and analyses, the influence mechanism of grooves on the tribological behavior of cylindrical roller thrust bearings was proposed and discussed.

When grooves textured bearings run under starved lubrication, their average coefficients of friction (COFs) and wear losses are all significantly reduced and much lower than those of smooth group. The influence of DPOG on the COF curves is significant, while the influence of WOG on the COF curves is a little weak. The influence of groove dimensions on the surface stresses of grooves textured bearings is weak, whether the WOG or DPOG. In this work, when the WOG is 100 µm and the DPOG is 15 µm, its average COF and wear loss are both the lowest, 0.0066 and 0.61 mg, respectively. Compared with the data of smooth group, its friction coefficient is reduced by 75.3% and its mass loss is reduced by 95.8%, showing a significant improvement in this condition.

This work can provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

The purpose of this paper is to report the tribological behavior of dimples textured rolling element bearings (REBs) under variable load and starved lubrication.

The pattern parameters include line-diameter of dimples (200 µm, 250 µm, 300 µm), depth of dimples (10 µm, 20 µm, 30 µm). Dimple patterns were prepared on the raceways of the shaft washers of cylindrical roller thrust bearings (CRTBs). A vertical wear test rig was used to obtain their coefficients of friction (COFs) under stepped load (1200–6000 N, with a manually increase of 1200 N every 3600 s) and starved lubrication. The wear losses and worn surfaces were characterized. The tribological performance between stepped load and fixed load (4000 N) was compared. The influence mechanism of dimples on the friction and wear properties of CRTBs under stepped load and starved lubrication was also discussed.

Compared with the data of smooth ones, the average COFs of the dimples textured bearings are almost all reduced under stepped load and starved lubrication, while their mass losses almost all get higher. The depth−diameter ratio and the effective volume coefficient of dimples are the important factors. In this work, compared with the smooth group, when the line-diameter of dimple is 250 µm and the depth is 20 µm, i.e. the depth−diameter ratio is 0.08, its average COF is reduced by 46.8% and its mass loss is reduced by about 7%, showing wonderful friction-reducing effect and good wear resistance.

This work can provide a reference for the raceway design of REBs.

The purpose of this paper is to reveal the influence of dimples on the tribological properties of the “washers-cage-rollers” system of rolling element bearing (REB) under starved lubrication.

A fiber laser marking system was used to prepare dimples patterns on the raceways of the shaft washers of cylindrical roller thrust bearings (CRTBs). The friction and wear properties of dimples textured CRTBs with different diameter of dimples (200 µm, 250 µm, 300 µm) and depth of dimples (4 µm, 8 µm, 12 µm) were researched through a vertical universal wear test rig using a customized tribo-pair under starved lubrication. The surface stresses and the influence mechanism of dimple units on the tribological behavior of REBs were also compared and discussed.

Although the surface stresses on the raceways of dimples textured bearings are significantly higher than that of the smooth group, the coefficients of friction and wear losses of them are all reduced under starved lubrication. When the effective volume of dimples is between 1.13 and 2.25 and the depth of dimples is smaller than 12 µm, the tribological properties of dimples textured CRTBs are significantly improved. In this work, when the diameter of dimples is 250 µm, and the depth of dimples is 8 µm, the textured bearings can provide the excellent friction-reduction ability and outstanding wear resistance.

This work is a valuable reference for the raceway design and optimization of REBs.

The great magnitude differences between the integral tunnel and its structure details make it impossible to numerically model and analyze the global and local seismic behavior of large-scale shield tunnels using a unified spatial scale, even with the help of supercomputers. The paper aims to present a combined equivalent & multi-scale simulation method, by which the tunnel's major mechanical properties under seismic loads can be represented by the equivalent model, and the seismic responses of the interested details can be studied efficiently by the coupled multi-scale model.

The nominal orthotropic material constants of the equivalent tunnel model are inversely determined by fitting the modal characteristics of the equivalent model with the corresponding segmental lining model. The critical sections are selected by comprehensive analyzing of the integral compression/extension and bending loads in the equivalent lining under the seismic shaking and the coupled multi-scale model containing the details of interest is solved by the mixed time explicit integration algorithm.

The combined equivalent & multi-scale simulation method is an effective and efficient way for seismic analyses of large-scale tunnels. The response of each flexible joint is related to its polar location on the lining ring, and the mixed time integration method can speed-up the calculation process for hybrid FE model with great differences in element sizes.

The orthotropic equivalent assumption is, to the best of the authors’ knowledge, for the first time, used in the 3D simulation of the shield tunnel lining, representing the rigidity discrepancies caused by the structural property.

Security is the most important issue in Internet of Things (IoT)-based smart cities and blockchain (BC). So, the present paper aims to detect and organize the literature regarding security in the IoT-based smart cities and BC context. It also proposes an agenda for future research. Therefore, the authors did a statistical review of security in IoT and BC in smart cities. The present investigation aims to determine the principal challenges and disturbances in IoT because of the BC adoption, the central BC applications in IoT-based smart cities and the BC future in IoT-based smart cities.

IoT) has a notable influence on modernizing and transforming the society and industry for knowledge digitizing. Therefore, it may be perceived and operated in real time. The IoT is undergoing exponential development in industry and investigation. Still, it contains some security and privacy susceptibilities. Naturally, the research community pays attention to the security and privacy of the IoT. Also, the academic community has put a significant focus on BC as a new security project. In the present paper, the significant mechanisms and investigations in BC ground have been checked out systematically because of the significance of security in the IoT and BC in smart cities. Electronic databases were used to search for keywords. Totally, based on different filters, 131 papers have been gained, and 17 related articles have been obtained and analyzed. The security mechanisms of BC in IoT-based smart cities have been ranked into three main categories as follows, smart health care, smart home and smart agriculture.

The findings showed that BC’s distinctive technical aspects might impressively find a solution for privacy and security problems encountering the IoT-based smart cities development. They also supply distributed storage, transparency, trust and other IoT support to form a valid, impressive and secure distributed IoT network and provide a beneficial guarantee for IoT-based smart city users’ security and privacy.

The present investigation aims to be comprehensive, but some restrictions were also observed. Owing to the use of some filters for selecting the original papers, some complete works may be excluded. Besides, inspecting the total investigations on the security topic in BC and the IoT-based smart cities is infeasible. Albeit, the authors attempt to introduce a complete inspection of the security challenges in BC and the IoT-based smart cities. BC includes significant progress and innovation in the IoT-based smart cities’ security domain as new technology. Still, it contains some deficiencies as well. Investigators actively encounter the challenges and bring up persistent innovation and inspection of related technologies in the vision of the issues available in diverse application scenarios.

The use of BC technology in finding a solution for the security issues of the IoT-based smart cities is a research hotspot. There is numerable literature with data and theoretical support despite the suggestion of numerous relevant opinions. Therefore, this paper offers insights into how findings may guide practitioners and researchers in developing appropriate security systems dependent upon the features of IoT-based smart city systems and BC. This paper may also stimulate further investigation on the challenge of security in BC and IoT-based smart cities. The outcomes will be of great value for scholars and may supply sights into future investigation grounds in the present field.

As the authors state according to their knowledge, it is the first work using security challenges on BC and IoT-based smart cities. The literature review shows that few papers discuss how solving security issues in the IoT-based smart cities can benefit from the BC. The investigation suggests a literature review on the topic, recommending some thoughts on using security tools in the IoT-based smart cities. The present investigation helps organizations plan to integrate IoT and BC to detect the areas to focus. It also assists in better resource planning for the successful execution of smart technologies in their supply chains.

The purpose of this paper is to examine Chinese consumers’ level of perception of genetically modified (GM) foods and the determinants of their willingness to pay (WTP) for Fad-3 GM lamb, a newly developed GM product.

Based on a randomized choice experiment involving 576 consumers in Beijing, the authors adopt a double-bounded contingent valuation method to estimate consumers’ WTP for Fad-3 GM lamb, as well as the causal impact of (randomized) product-information disclosure on it.

The econometric result indicates that the randomly disclosed product information describing details about Fad-3 GM lamb, the potential risks associated with the consumption of it, and the related governmental regulation policies raised consumers’ WTP by 6.2 yuan per Jin (or US$2/kilogram).

This paper provides new experimental evidence of the effect of product-information disclosure on consumers’ WTP for a newly developed GM food product.

Coal is a critical global energy source, and fluctuations in its price significantly impact related enterprises' profitability. This study aims to develop a robust model for predicting the coal price index to enhance coal purchase strategies for coal-consuming enterprises and provide crucial information for global carbon emission reduction.

The proposed coal price forecasting system combines data decomposition, semi-supervised feature engineering, ensemble learning and deep learning. It addresses the challenge of merging low-resolution and high-resolution data by adaptively combining both types of data and filling in missing gaps through interpolation for internal missing data and self-supervision for initiate/terminal missing data. The system employs self-supervised learning to complete the filling of complex missing data.

The ensemble model, which combines long short-term memory, XGBoost and support vector regression, demonstrated the best prediction performance among the tested models. It exhibited superior accuracy and stability across multiple indices in two datasets, namely the Bohai-Rim steam-coal price index and coal daily settlement price.

The proposed coal price forecasting system stands out as it integrates data decomposition, semi-supervised feature engineering, ensemble learning and deep learning. Moreover, the system pioneers the use of self-supervised learning for filling in complex missing data, contributing to its originality and effectiveness.

The purpose of this paper is to provide readers with the main findings and conclusions of papers presented at the 2011 CAER‐IFPRI International Conference held under the theme “Is China entering a high food price era?”

The authors conduct a desk review of papers presented at the conference and provide a brief summary of the analytical tools, and main findings and conclusions of each presentation.

These reviews show that, while there seems to be an increase in the prices of agricultural commodities on the Chinese market, in real terms, these rises fall far below the increases in the prices of industrial commodities. Thus, expert views remain divided on whether China is entering an era of high food price.

The discussions initiated by the conference theme aroused researchers' curiosities for further studies into understanding the current level of food prices in China.

This literature review explores the potential of gamification in workplace learning beyond formal training. The study also highlights research gaps and opportunities for scholars to develop new theories and methodologies to enhance the understanding and application of gamification in workplace learning. It provides guidance for managers to use gamification to enhance learning and engagement. Ultimately, this review presents gamification as a promising field of study to increase individual and organizational performance.

Literature review of 6625 papers in the timeframe 1990–2020, with an update to include papers published in 2023.

This article examines the impact of gamification beyond formal learning and its potential to enhance employee productivity and well-being in the workplace. While there has been extensive research on gamification in formal learning contexts, little is known about its impact on informal learning. The study argues that the context of gamification is crucial to extending its effects and discusses the role, antecedents and consequences of game design elements in the workplace. The article also explores how the learning context relates to employee learning during work. Further research is necessary to investigate the impact of individual characteristics on work experience and performance.

Intended contribution of the present study is the development of a theoretical framework exploring the benefits of gamification in a work context.

For practicing managers, this paper shows how to use gamification to increase workplace learning and employee engagement, not just in the context of formal learning—as some companies already do today—but also systematically, in the context of informal learning.

This study explores the impact of gamification on informal workplace learning and emphasizes the significance of the context of gamification in extending its effects to improve individual and organizational performance.

The purpose of this paper is to study the functionality of additively manufactured (AM) parts, mainly depending on their dimensional accuracy and surface finish. However, the products manufactured using AM usually suffer from defects like roughness or uneven surfaces. This paper discusses the various surface quality improvement techniques, including how to reduce surface defects, surface roughness and dimensional accuracy of AM parts.

There are many different types of popular AM methods. Unfortunately, these AM methods are susceptible to different kinds of surface defects in the product. As a result, pre- and postprocessing efforts and control of various AM process parameters are needed to improve the surface quality and reduce surface roughness.

In this paper, the various surface quality improvement methods are categorized based on the type of materials, working principles of AM and types of finishing processes. They have been divided into chemical, thermal, mechanical and hybrid-based categories.

The review has evaluated the possibility of various surface finishing methods for enhancing the surface quality of AM parts. It has also discussed the research perspective of these methods for surface finishing of AM parts at micro- to nanolevel surface roughness and better dimensional accuracy.

This paper represents a comprehensive review of surface quality improvement methods for both metals and polymer-based AM parts.