Search results

Wind power is an important source of renewable energy and accounts for significant portions in supplying electricity in many countries and locations. The purpose of this paper is to develop a method for wind power system reliability assessment and condition-based maintenance (CBM) optimization considering both turbine and wind uncertainty. Existing studies on wind power system reliability mostly considered wind uncertainty only and did not account for turbine condition prediction.

Wind power system reliability can be defined as the probability that the generated power meets the demand, which is affected by both wind uncertainty and wind turbine failures. In this paper, a method is developed for wind power system reliability modeling considering wind uncertainty, as well as wind turbine condition through health condition prediction. All wind turbine components are considered. Optimization is performed for maximizing availability or minimizing cost. Optimization is also conducted for minor repair activities to find the optimal number of joint repairs.

The wind turbine condition uncertainty and its prediction are important for wind power system reliability assessment, as well as wind speed uncertainty. Optimal CBM policies can be achieved for optimizing turbine availability or maintenance cost. Optimal preventive maintenance policies can also be achieved for scheduling minor repair activities.

This paper considers uncertainty in both wind speed and turbine conditions and incorporates turbine condition prediction in reliability analysis and CBM optimization. Optimization for minor repair activities is studied to find the optimal number of joint repairs, which was not investigated before. All wind turbine components are considered, and data from the field as well as reported studies are used.

Sulfate-reducing bacteria (SRB) are recognized by scholars as the most important class of bacteria leading to corrosion of metal materials. It is important to use the properties of microorganisms to inhibit the growth of SRB in the corrosion protection of metal materials and to protect the environment.

In this work, the behavior of anaerobic Thiobacillus denitrificans (TDN) intracellular enzyme inhibition of SRB corrosion of EH36 steel was investigated with electrochemical impedance spectroscopy, biological detection technology and X-ray photoelectron spectroscopy.

Results showed that the SRB crude intracellular enzyme affected the corrosion behavior of EH36 steel greatly and the purified TDN intracellular enzyme inhibits SRB intracellular enzyme corrosion to EH36 steel.

A perfect enzyme activity inhibition mechanism will provide theoretical guidance for the selection and application of anticorrosion microorganisms, which is of scientific significance in the field of microbial anticorrosion research.

Principal leadership is an important external environmental factor that affects and alleviates teachers' job burnout. The purpose of this paper is to explore the deep internal mechanisms of the influence of principal transformational leadership on teacher job burnout in the context of Chinese teachers.

A cluster sampling method was used to conduct a questionnaire survey on 990 elementary school teachers in 14 primary schools in Beijing. This study uses a structural equation model to analyze the chain intermediary effect of social-emotional competence and the student-teacher relationship between transformational leadership and teachers' job burnout.

The results reveal that transformational leadership has a significant negative predictive effect on teachers' job burnout; this kind of leadership affects teachers' job burnout through a chain intermediary effect of social and emotional competence and student-teacher relationship.

This research has discovered that teacher burnout is the result of the interaction of external environmental and individual internal factors. Transformational leadership, as an external environmental factor, positively predicts the internal social-emotional competence of the teacher, and then the teacher's internal social-emotional competence positively predicts the external student-teacher relationship. Finally, the teacher-student relationship of the external environment negatively predicts the job burnout of internal individual teachers.

The purpose of this paper is to examine whether different corporate social responsibility (CSR) dimensions, namely, workplace economic responsibility, legal responsibility, ethical responsibility, philanthropic responsibility and environmental responsibility, have different influence on job pursuit intention among undergraduate students in Malaysia.

The target respondents are undergraduate business students from five leading private universities in Malaysia. Primary data were collected through survey questionnaires via face-to-face method. Five-point Likert scale was used to assess the variables and to measure the items. Collected data were tested through SAS software and analysed with descriptive and inferential analyses.

Four out of the five CSR dimensions significantly influence job pursuit intention with ethical responsibility being the exception.

This study proved that the adoption of CSR in an organisation will become a competitive advantage to attract new talents. Also, this is an improved research model by adopting multi-dimensional perspectives of CSR.

This proposed framework with a combination of five CSR dimensions (workplace economic responsibility, legal responsibility, ethical responsibility, philanthropic responsibility and environmental responsibility) is useful to future researchers as it enables them to have a broader view on CSR and its effect on job pursuit intention.

Different information sharing mechanisms and online platform information sharing to different charging models are compared and analyzed.

This paper uses the Stackelberg game model to study the demand information sharing and pricing decisions.

The results show that: (1) the retailer's pricing strategy is the highest when both of them obtain information, while the manufacturer's pricing strategy is affected by the related attributes of different products, such as the sensitivity of consumers to product prices; (2) in the online platform sales model, the demand information data sharing owned by the online platform can bring more expected profits to the whole supply chain and the members of the supply chain, and the higher the accuracy of the information, the higher the expected profit; (3) when the cost of obtaining demand information is zero, that is, the online platform shares the information data about market demand free of charge, the retailer and manufacturer tend to obtain information; (4) for the online platform, charging a certain fee can achieve higher expected profits than free sharing.

Based on the single platform online sales model, this paper uses the Stackelberg game model to study the demand information sharing and pricing decision of a manufacturer and a retailer selling products through the same online platform.

The purpose of this paper was to attempt to confirm the root cause of wafer damage issue by heavy Al wire wedge bonding and propose some permanent solutions for it.

The infra red–optical beam-induced resistance change (IR-OBIRCH) analysis defines the position of an abnormal hotspot. A cross section and an scanning electron microscope (SEM) confirmed the wafer damage issue and its position. Based on the position of wafer damage, the wedge tool with different life and Al buildup was checked found to be on the wedge tool. Finite element analysis (FEA) modeling analysis and simulation experiment guarantee the Al buildup, and low wedge deformation thickness (WDT) can cause the wafer damage issue. Finally, design of experiment (DOE) experiments are designed to optimize wedge tool dimension and wedge-bond parameters to eliminate wafer damage issue.

Wafer damage issue caused the Vpwr-OUTPUT leakage issue by IR-OBIRCH analysis. Al buildup was found on wedge tool with different life and its size gets larger along with the increase in wedge tool life. Low WDT and bigger Al buildup can cause the wafer damage. Designing new wedge tool and parameters optimization can increase WDT.

Because of the limitation of time and resources, finite element method (FEM) modeling and wedge tool dimension could not be studied more deeply.

This paper sets an example on how to find out the root cause of wafer damage by a step-by-step analysis and put forward a quick solution accordingly for the issue.

The purpose of this paper is to examine the effects of gravity variables and trade costs on China's export margins.

Following the structural gravity model with firm heterogeneity, the paper measures the extensive margins and intensive margins of China's export across 46 export destinations and estimates the linkage between export margins and its potential determinants.

The empirical results confirm the gravity relationship hold for bilateral trade and export margins. Furthermore, trade costs have different influence on extensive margins and intensive margins as the structural gravity model with firm heterogeneity expected. The paper also shows the rapid growth of China's export is mainly along the intensive margins which are increasing in fixed cost for export.

The paper contributes to the measurements of China's export margins and the empirical research on effects of trade liberalization on China's foreign trade.

Aircraft structures are mainly connected by riveting joints, whose quality and mechanical performance are directly determined by vertical accuracy of riveting holes. This paper proposed a combined vertical accuracy compensation method for drilling and riveting of aircraft panels with great variable curvatures.

The vertical accuracy compensation method combines online and offline compensation categories in a robot riveting and drilling system. The former category based on laser ranging is aimed to correct the vertical error between actual and theoretical riveting positions, and the latter based on model curvature is used to correct the vertical error caused by the approximate plane fitting in variable-curvature panels.

The vertical accuracy compensation method is applied in an automatic robot drilling and riveting system. The result reveals that the vertical accuracy error of drilling and riveting is within 0.4°, which meets the requirements of the vertical accuracy in aircraft assembly.

The proposed method is suitable for improving the vertical accuracy of drilling and riveting on panels or skins of aerospace products with great variable curvatures without introducing extra measuring sensors.

To improve humanized management of Chinese teachers, the aim of this study is to, first, investigate the stress of Chinese teachers, and, second, to examine the relationship of teacher stress with coping strategies and social support. Moreover, an attempt is made to examine the moderating role of coping strategies in the relationship between social support and teacher stress.

Participants consisted of 363 teachers from 6 public primary and secondary schools (both regular and vocational schools), who completed 3 self-report questionnaires examining teacher stress, coping strategies and social support. The methodology used was t-test, correlation analysis and hierarchical multiple regression analysis.

There are more than 50 per cent of primary and secondary school teachers suffering from mild to extremely severe stress. Working environment (regular or vocational schools), gender and age affect teacher stress. Social support and passive strategies have significant relationships with teacher stress, and passive strategies moderate the relationship between social support and teacher stress.

The study is based on a sample taken from public primary and secondary schools, and the character of the research was cross-sectional. Therefore, we must be cautious in generalizing the findings. An important implication for management of the findings of this study is the importance of humanized management for teachers. To reduce teacher stress, more social support should be provided by educational administrators, and teachers should be trained to avoid using passive strategies.

Through the investigation into the teacher stress in both regular and vocational schools, this study provides a new point of view for human resource managers to control and reduce teacher stress in China by improved humanized management.

The construction industry has a significant function in improving the quality of life in the urban environment; meanwhile, greening the supply chain is becoming a seriously pressing issue in the construction industry. This paper seeks to select green suppliers in construction projects implemented at Iranian state universities via multicriteria decision-making (MCDM) models through rough set theory.

A mixed methodology design was conducted through a literature review of studies concerned with green suppliers to identify the related criteria and the rough MCDM techniques. As such, 15 criteria were finalized through content validity ratio (introduced by Lawshe, 1975). The weights of the criteria were calculated through the rough AHP and the suppliers were prioritized using the rough TOPSIS to contribute to the Construction Department.

The study proposed a hierarchical structure of the decision process for green supplier selection in construction projects. According to the weighting results, environmental awareness, green social responsibility and the environmental management system were the most important criteria.

Because the scope of the study was limited to state universities and the methods worked according to the experts' views, the results should be generalized with more caution. The validity of the results should be examined by applying the model to similar contexts.

The study conceptualizes green supplier selection in construction projects at state universities. Furthermore, the method used makes it possible to deal with the uncertainty arising from experts' limited awareness of only part of the problem rather than the whole system under investigation.