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With the rapid increase in the number of installed wind turbines (WTs) worldwide, requirements and expenses of maintenance have also increased significantly. The condition monitoring (CM) of WT provides a strong “soft guarantee” for preventive maintenance. The supervisory control and data acquisition (SCADA) system records a huge amount of condition data, which has become an effective means of CM. The main objective of the present study is to summarize the application of SCADA data to fault detection in wind turbines, analyze its advantages and disadvantages and predict the potential of future investigations on the use of SCADA data for fault detection.

The authors first review the means of WT CM and summarize the characteristics of CM based on SCADA data. To ensure the quality of SCADA data, data preprocessing methods are analyzed and compared. Then, the failure modes of the key components are discussed and the SCADA data used for fault detection of each component are compared. Moreover, the fault detection methods for WT are classified and a general framework for fault detection is proposed. Finally, the issues in the WT fault detection method based on SCADA data are reviewed.

Based on the performed analyses, it is found that although the fault detection accuracy based on SCADA data is relatively poor, it has low capital expenses and low computational cost. More specifically, when there is scarce fault data, the normal SCADA data can be used to detect the fault time. However, the specific fault type cannot be identified in this way. When a large amount of fault data are accumulated in the SCADA system, it can not only detect the occurrence time of the fault but also identify the specific fault type.

The main contribution of the present study is to summarize the pre-processing methods for SCADA data, the data required for fault detection of key components and the characteristics of the fault detection model. Then we propose a general fault detection framework for wind turbines based on SCADA data, where the maintenance workers can choose the appropriate fault detection method according to different fault detection requirements and data resources. This article is expected to provide guidance for fault detection based on time-series sensor signals and be of interest to researchers, maintenance workers and managers.

This paper aims to anticipate the possible development direction of WAAM. For large-scale and complex components, the material loss and cycle time of wire arc additive manufacturing (WAAM) are lower than those of conventional manufacturing. However, the high-precision WAAM currently requires longer cycle times for correcting dimensional errors. Therefore, new technologies need to be developed to achieve high-precision and high-efficiency WAAM.

This paper analyses the innovations in high-precision WAAM in the past five years from a mechanistic point of view.

Controlling heat to improve precision is an effective method. Methods of heat control include reducing the amount of heat entering the deposited interlayer or transferring the accumulated heat out of the interlayer in time. Based on this, an effective and highly precise WAAM is achievable in combination with multi-scale sensors and a complete expert system.

Therefore, a development direction for intelligent WAAM is proposed. Using the optimised process parameters based on machine learning, adjusting the parameters according to the sensors’ in-process feedback, achieving heat control and high precision manufacturing.

This paper aims to examine the association between green innovation and the cost of equity in China. This study relies on the investors’ base perspective and shareholders’ perceived risk perspective to investigate the relation between green innovation and the cost of equity in China.

The paper uses firm-fixed effect regression for a sample of Chinese public companies for the period 2008–2018.

The authors find a negative relationship between green innovation and the cost of equity capital. This negative association is found to be more pronounced for less financially constrained firms, during periods of high economic policy uncertainty, and for firms with a strong internal control environment. Finally, the paper shows that the negative association became more pronounced after the passage of the Environmental Protection Law of China in 2012. The results remain robust to possible endogeneity concerns.

This study contributes to the green innovation literature by documenting that shareholders favorably view firms implementing green innovation policies. The study also has policy implications for Chinese regulators in improving the green credit policy.

Nowadays, green cutting has become the focus because of its ecological problem and the necessary environment protection, so that the research on experimentation of green cutting with water vapor as coolant and lubricant is studied because water vapor has many benefits of cheapness, no pollution, no harm and no recycling and handling.

The vapor generator and the vapor feed system are manufactured, the distribution of temperature and velocity of vapor jet flow are simulated by MATLAB program, and under the conditions of compress air, oil water emulsion, water vapor as coolant and lubricant and dry cutting, respectively, the turning experimentation of comparison which the tool is YT15, and the working material is steel 45.

Water vapor, as coolant and lubricant, the cutting force is reduced, respectively about 30‐40, 20‐30 and 10‐15 percent by comparing to dry cutting, compressed air and oil water emulsion. The cutting temperature is, respectively about 30, 40 and 50 percent with the other conditions of dry cutting, compressed air and oil water emulsion. The friction coefficient and the chip deformation coefficient are correspondingly decreased and the surface roughness value has been diminished too. Through analysis of the experimental results, water vapor as coolant and lubricant possesses better lubricating action because of the excellent penetration performance and the low lubrication layer shearing strength of water vapor.

Water vapor as coolant and lubricant provides a novel method for realizing no contamination green cutting.

This study aims to examine the relationship between board capital and firm performance in the Chinese tourism industry.

The study’s sample includes firms from the Chinese hotel, air transportation/travel and catering industries. This study explores the governance environment in tourism industries. This study estimates three dimensions of the board, including education, expertise and directors interlock. These dimensions are further grouped as human capital (i.e. education and expertise), social capital (interlocks) and board capital (sum of social and human capital). Ordinary least square regressions with multiple robustness tests are used to investigate the effect of board capital on firm value in Chinese listed tourism firms during 2005–2018.

This study finds that board capital positively impacts firm performance in its dimensions of human and social capital. This study also highlights the two important ownership contexts, namely, institutional investors and state-ownership, that shape the board capital-firm performance association in the Chinese tourism industry.

The findings suggest that board capital plays a significant role in corporate decisions. The results illustrate that higher board capital improves both governance mechanisms and resource provision roles of the board, resulting in higher firm value. The results further offer implications for managers and shareholders of tourism firms when electing directors as shareholders’ representatives.

The study has two important contributions. First, it extends the prior literature of firm value by considering the board’s human and social dimensions in the tourism sector. Second, contrary to prior research on board, this study takes three facets of board capital, education, expertise and interlocks that improve governance mechanisms and bring new resources in the shape of skills, knowledge and expertise.

Through this research study, the authors found that digital thread has made significant progress in the life cycle management of the US Air Force. The authors hope that by reviewing similar studies in the aerospace field, the meaning of digital thread can be summarized and applied to a wider range of fields. In addition, theoretically, the definition of digital twin and digital thread are not unified. The authors hope that the comparison of digital thread and digital twin will better enable scholars to distinguish between the two concepts. Besides, the authors are also looking forward that more people will realize the significance of digital thread and carry out future research.

Complete research about digital thread and the relevant concept of the digital twin is conducted. First, by searching in Google Scholar with the keyword “digital thread”, the authors filter results and save literature with high relevance to digital thread. The authors also track these papers’ references for more paper of digital thread and digital twin. After removing the duplicate and low-relevance literature, 72 digital thread-related literature studies are saved and further analyzed from the perspective of time development, application field and research directions.

Digital thread application in industries other than the aviation manufacturing industry is still relatively few, and the research on the application of digital thread in real industrial scenarios is mainly at the stage of framework design and design-side decision optimization. In addition, the digital thread needs a new management mechanism and organizational structure to realize landing. The new management mechanism and the process can adapt to the whole life cycle management process based on the digital thread, manage the data security and data update, and promote the digital thread to play a better effect on the organizational management.

Based on a review of digital thread, future research directions and usage suggestions are given. The fault diagnosis of high-speed train bogie as an example shows the effectiveness of the method and also partially demonstrates the advantages and effects brought by the digital thread connecting the data models at various stages.

This paper first investigates and analyzes the theoretical connotation and research progress of digital thread and gives a complete definition of digital thread from the perspective of the combination of digital thread and digital twins. Next, the research process of digital thread is reviewed, and the application fields, research directions and achievements in recent years are summarized. Finally, taking the fault diagnosis of high-speed train bogie as an example partially demonstrates the advantages and effects brought by the digital thread connecting the data models at various stages.

Water-based graphite lubricants have good lubricity in the process of metal forming, especially for hot-rolling seamless pipe. Although the use of water as a working fluid system instead of conventional mineral oil has many advantages for the fuel consumption, post cleaning and a new type of lubricant, the graphite contaminated the machine and workers for its physical properties. From the global environmental protection viewpoint, it is urgent to develop a kind of benign material.

Magnesium hydroxide which has the average particle size of 10 μm was chosen as a base material without further modification and pretreatments. On the HT-1000 high-temperature tribometer, the influence of temperature and lubricant materials on the friction coefficient was studied. The tribological performance at 900^°C provided evidence under high temperature for exploring a new lubricant material.

Tap water-based brucite lubricant will open a new chapter in the industrial lubrication, effectively avoiding many unfavorable factors caused by graphite lubrication, such as conductivity, pollution and energy loss. Meanwhile, it expanded the application of brucite as flame-retardant agent, catalyst, water treatment agent and so on.

It is a new and environmental lubricant to tap water-based brucite lubricant. And specially, the preparation process of lubricant is simple and economical.

Porous silicon (PS) was successfully fabricated using an alternating current photo-assisted electrochemical etching (ACPEC) technique. This study aims to compare the effect of different crystal orientation of Si n(100) and n(111) on the structural and optical characteristics of the PS.

PS was fabricated using ACPEC etching with a current density of J = 10 mA/cm² and etching time of 30 min. The PS samples denoted by PS₁₀₀ and PS₁₁₁ were etched using HF-based solution under the illumination of an incandescent white light.

FESEM images showed that the porous structure of PS₁₀₀ was a uniform circular shape with higher density and porosity than PS₁₁₁. In addition, the AFM indicated that the surface roughness of porous n(100) was less than porous n(111). Raman spectra of the PS samples showed a stronger peak with FWHM of 4.211 cm⁻¹ and redshift of 1.093 cm⁻¹. High resolution X-ray diffraction revealed cubic Si phases in the PS samples with tensile strain for porous n(100) and compressive strain for porous n(111). Photoluminescence observation of porous n(100) and porous n(111) displayed significant visible emissions at 651.97 nm (Eg = 190eV) and 640.89 nm (Eg = 1.93 eV) which was because of the nano-structure size of silicon through the quantum confinement effect. The size of Si nanostructures was approximately 8 nm from a quantized state effective mass theory.

The work presented crystal orientation dependence of Si n(100) and n(111) for the formation of uniform and denser PS using new ACPEC technique for potential visible optoelectronic application. The ACPEC technique has effectively formed good structural and optical characteristics of PS.

Multiple-input multiple-output (MIMO) combined with multi-user massive MIMO has been a well-known approach for high spectral efficiency in wideband systems, and it was targeted to detect the MIMO signals. The increasing data rates with multiple antennas and multiple users that share the communication channel simultaneously lead to higher capacity requirements and increased complexity. Thus, different detection algorithms were developed for the Massive MIMO.

This paper focuses on the various literature analyzes on various detection algorithms and techniques for MIMO detectors. Here, it reviews several research papers and exhibits the significance of each detection method.

This paper provides the details of the performance analysis of the MIMO detectors and reveals the best value in the case of each performance measure. Finally, it widens the research issues that can be useful for future researchers to be accomplished in MIMO massive detectors

This paper has presented a detailed review of the detection of massive MIMO on different algorithms and techniques. The survey mainly focuses on different types of channels used in MIMO detections, the number of antennas used in transmitting signals from the source to destination, and vice-versa. The performance measures and the best performance of each of the detectors are described.

This study aims to analyze the impact of corporate governance on firms’ external financing decisions in the Middle East and North Africa (MENA) region.

The authors analyzed a unique set of panel data comprising 2,425 nonfinancial firms whose shares are traded on stock exchanges in countries in the MENA region. The authors fitted an ordinary least squares model to estimate the regression coefficients. The authors performed a sensitivity analysis using alternative measures of the critical variables and an endogeneity analysis using instrumental variable methods with plausible external instruments.

The results revealed that corporate governance characteristics of firms are strongly associated with their degree of leverage. They also showed that macrofinancial conditions, financial regulations, corporate governance enforcement and social conditions mitigate the impact of corporate governance on firms’ financing decisions.

A larger sample size will further improve the results; however, this is difficult and depends on the extent to which increasing disclosure practices allow more corporate information to reach international databases.

This study provides new evidence on the role of corporate governance on firms’ financing decisions and documents the essential mitigating role of institutions, alerting managers to consider them.

This study is a novel attempt. Based on information from different data sources, this study explored the predictive power of corporate governance, ownership structures and other firm-specific characteristics in explaining corporate leverage in MENA countries. Overall, the analysis provides new evidence of the association between corporate governance and capital structure in the MENA region, highlighting the critical role of institutions.