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Design of Pitch Angle Control Using Improved Strategies for Wind Turbine System
No full textIn the past two decades, energy shortages and environmental pollution have become increasingly serious in the world. Therefore, wind energy, as a renewable and clean energy, has received high attention from many countries such as China, the United States, Brazil and so on. Wind power generation has developed rapidly. However, the difficulty of wind power generation lies in the randomness of wind energy and the strong nonlinearity of wind turbine generator system (WTGS). Traditional control method such as single Proportional Integral Differential (PID) theory is difficult to achieve ideal control effect. In order to improve the dynamic performance of WTGS in the constant power operating region, high-performance hybrid controllers were designed in this research. When the wind speed is above the rated value, the rotor speed and output power of the WTGS can be maintained at the rated value. Firstly, a nonlinear mathematical model of WTGS was established and linearized at multiple operating points by adapting Taylor's formula to obtain multiple linear subsystems. Secondly, the optimal control theory or H-infinity theory was applied to design variable pitch controller for each linear subsystem, then a hybrid variable pitch controller was obtained by combining Takagi-Sugeno (T-S) fuzzy theory or back propagation (BP) neural network theory. Therefore, three hybrid controllers were designed in this research, namely T-S optimal hybrid pitch controller, T-S H-infinity hybrid pitch controller, and BP neural network hybrid pitch controller. Finally, simulations were conducted in MATLAB to verify the performance of the three controllers. The WTGS used in the simulation is a 600kW experimental unit from the National Renewable Energy Laboratory (NREL) of the United States. The simulation was conducted under five different wind conditions: gust wind, gradient wind, step wind, random wind and combined wind. The simulation results show that when the wind speed changes, all the three controllers can stabilize the rotor speed at the rated value of 4.35 rad/s and the output power at the rated value of 600 kW. The response time and overshoot are both less than that of PID controller, indicating that the control effect is more ideal. When the wind speed jumps from 13 m/s to 15 m/s, comparing the data under the three controllers, from the simulation wave form it can be seen that the response time of the T-S H-infinity hybrid pitch controller is 2 seconds and the overshoot is 25.0%, which are the smallest among the three controllers
ANALYSING THE POVERTY REDUCTION EFFECT OF CHINA’S DIRECT INVESTMENT IN BELT AND ROAD COUNTRIES
No full textThis study investigates the poverty reduction effect of China’s direct investment in countries along the Belt and Road Initiative (BRI). Using panel data from 63 countries over the period 2009 to 2019, we employ an econometric model and mediation analysis to examine the impact mechanisms. The findings reveal that China’s Foreign Direct Investment (FDI) significantly reduces poverty by stimulating employment and improving infrastructure. Regional disparities are evident, with stronger effects in South and Southeast Asia. The study underscores the significance of targeted investments in infrastructure and job creation, offering actionable insights for policymakers and investors. The empirical results indicate that China’s FDI can significantly reduce the poverty rate of poor families in countries along the Belt and Road, which greatly reduces the number of poor people in these countries and effectively promotes local economic development. In addition, the results contribute to the growing literature on the socioeconomic impacts of international investment and provide a foundation for further exploration into development strategies under the BRI framework
A Green Internet of Things (GIoT) Adoption Framework to Enhance Environmental Performance of SMEs Through the Digital Social Networking
Get PDFSmall and Medium Enterprises (SMEs) face increasing pressure to adopt sustainable practices, yet the adoption of advancedtechnologies like the Green Internet of Things (GIoT) remains limited. This study addresses this gap by proposing and validatinga GIoT adoption framework aimed at enhancing environmental performance, emphasizing the mediating role of digital socialnetworking (DSN). Extending the Unified Theory of Acceptance and Use of Technology (UTAUT), the model incorporates per-ceived motivation and perceived environmental knowledge as additional predictors. A quantitative survey of 614 SME ownersand managers from manufacturing and service sectors was conducted, and structural equation modelling (SEM) was used foranalysis. Results show that all UTAUT constructs, along with the extended variables, significantly influence GIoT adoption.GIoT adoption directly improves environmental performance and promotes DSN, which further amplifies its positive environ-mental impact. The study also reveals that manufacturing SMEs exhibit a stronger intent to adopt GIoT. Implications for policyand practice are discussed
Morphological and Biochemical Characterization of a Cellulose-Degrading Bacteria isolated from Horse Feces (Equus caballus)
Get PDFCellulase is a widely developed enzyme for industrial applications, produced by various sources, including bacteria. While numerous bacteria are known to produce cellulose-degrading enzymes (CDE), further exploration is needed to discover unique and highly active CDEs. This study focuses on screening, identifying, and characterizing cellulose-degrading bacteria (CDB) from horse faces, which are considered an excellent source for such bacteria. Fecal samples were collected from Megastar Horse Farm in Batu, Malang, and screened on carboxymethyl cellulose (CMC)-containing agar, incubated at 37 °C. The colonies that formed halo zones on the agar were isolated, and their genomic DNA was extracted for 16S rRNA gene amplification. Sequence analysis revealed that the isolate showed over 98% similarity to B. amyloliquefaciens SLBD and was subsequently labeled as B. amyloliquefaciens SLBD. Gram staining and scanning electron microscopy confirmed that B. amyloliquefaciens SLBD is Gram-positive with a rod-shaped morphology. B. amyloliquefaciens SLBD also grew optimally in Luria-Bertani (LB) medium at 37 °C. The CDE activity of this strain was assessed using its extracellular fraction against CMC and mannan oligosaccharides (MOS), revealing a substrate-dependent activity profile, with CMC being the preferred substrate
The Impact of China's New Securities Law on Audit Quality and Fees: Moderating Effect of Internal Control and Media Coverage
Get PDFThe China’s new Securities Law implemented in 2020 lowered the entry barriers for audit firms in the securities market, thereby intensifying competition within the audit sector. It also introduced a series of policy measures that further strengthened the regulation of listed companies and auditors, as well as increased the severity of penalties for violations. This study aims to investigate the impact of the new Securities Law on changes in audit quality and audit fees. Additionally, the study explores the moderating roles of internal control as an internal supervisory mechanism and media coverage as an external supervisory mechanism. Based on data from Chinese listed companies from 2016 to 2022, the study employs a Difference-in-Differences (DiD) approach to empirically test the hypotheses.
The findings reveal that the implementation of the new Securities Law has significantly improved the audit quality of listed companies, with the effect being particularly pronounced in firms with weaker internal controls. Moreover, extensive media coverage further amplifies the positive impact of the law on audit quality. Simultaneously, the study observes a significant increase in audit fees following the implementation of the law, reflecting the heightened compliance requirements and stricter regulatory scrutiny that influence auditors' pricing decisions. This increase in audit fees is less pronounced in companies with stronger internal controls, indicating that robust internal controls can mitigate some of the cost pressures associated with the new regulations. These results are consistent with the predictions of audit risk theory and reputation theory. The study employs rigorous robustness tests, including parallel trends test, placebo tests, and Propensity Score Matching Difference-in-Differences (PSM-DiD) analyses, to confirm the reliability of the findings.
The study provides important insights into how the China’s new Securities Law impacts audit quality and audit fees. Overall, while the revised Securities Law has successfully enhanced market transparency and audit quality, it has also increased compliance costs for companies with lower governance standards. These findings carry significant theoretical and practical implications for policymakers, regulators, and market participants in China and other emerging economies
The Determinant of Total Factor Productivities in China’s Urban Agglomerations
Get PDFChina's urban agglomerations (UA) have become pivotal engines of national economic growth, facilitating regional transformation and broader socioeconomic advancement. However, despite the rapid development, China is currently experiencing an overall economic slowdown. Existing studies have predominantly focused on individual cities, often neglecting the regional dynamics and integrative nature of UA. Furthermore, with diminishing returns from traditional factor-driven models, there is an urgent need to evaluate and transition towards innovation-led growth.
This study aims to bridge the knowledge gap by assessing the changing trends of TFP in China’s six major UA from 2010 to 2019. Specifically, it seeks to: (i) evaluate TFP levels across major UAs; (ii) conduct horizontal comparisons of TFP dynamics among these regions; and (iii) identify the key factors influencing TFP growth. Using panel data from 92 cities and employing the DEA-Malmquist method, the study measures TFP and its decomposition indicators to examine regional disparities and the driving forces of economic efficiency. A dynamic panel model is constructed to empirically test the influence of various determinants such as government investment, industrial structure, and urbanization level.
The findings reveal that TFP-led growth in China’s urban agglomerations is not merely a by-product of expansion but reflects a dynamic equilibrium shaped by the strategic allocation of innovation resources and the alignment of complex development goals. Significant heterogeneity exists among the six major UA, with discernible growth trajectories categorized into stable advancement, cyclical volatility, and structural transformation. These patterns underscore uneven regional capacities to leverage innovation for productivity gains. The analysis further identifies government technological investment and the pace of urbanization as consistent drivers of TFP improvement. However, structural inefficiencies—such as rigid industrial composition, insufficient R&D capability, and limited openness—continue to impede sustainable productivity growth. These constraints suggest that without targeted policy interventions to restructure industrial bases and enhance innovation ecosystems, the transformative potential of UA may remain underutilized. This study offers new empirical evidence for understanding regional productivity disparities and provides theoretical and policy guidance for advancing high-quality, innovation-driven, and sustainable urban development in China
Evaluating Cross-Border E-CommerceDevelopment and Trade Potential Between China and RCEP Countries : An Ecosystem-Based Gravity Model Approach
Get PDFThis study explores the development level and trade potential of cross-border e-commerce (CBEC) between China and its Regional Comprehensive Economic Partnership (RCEP)
partners. Based on the CBEC ecosystem theory, a composite development index is constructed using Principal Component Analysis (PCA), incorporating key variables such as logistics performance, information flow, and digital infrastructure. An extended gravity model, estimated through the Generalized Method of Moments (GMM), is applied to panel
data covering the period from 2013 to 2022. The empirical results underscore the crucial role of logistics and information flow in promoting CBEC growth across the region. China maintains a leading position due to its superior infrastructure, while countries like Laos remain constrained by infrastructural and economic limitations. The study finds that CBEC development in partner countries significantly enhances their trade with China, whereas China’s own CBEC level has a limited effect on overall trade volumes. Additionally, while partner countries’ per capita GDP does not exhibit a significant influence, China’s per capita
GDP positively affects trade flows, and geographic distance has a weak but statistically significant negative impact. The analysis also reveals untapped CBEC trade potential in
countries such as Japan and South Korea, indicating the need for targeted policy interventions to strengthen digital infrastructure, reduce trade frictions, and foster deeper e-commerce integration within the RCEP framework
Pekeliling Pentadbiran Bil. 12 Tahun 2025: Garis Panduan Pelaksanaan Hari Senggang / Program SEJAHTERA Universiti Malaysia Sarawak (UNIMAS)
No full textFuzzy Technique for Order Preference by Similarity to Ideal Solution Based Optimization for Grid-Connected Solar PV System
No full textThis study presents an optimization framework for grid-connected solar photovoltaic (PV) systems using the Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (F-TOPSIS). With the growing demand for sustainable energy solutions, the research addresses the dual objective of maximizing power output while minimizing capital costs
under architectural, financial, and energy constraints. A detailed case study involving real world building parameters and energy consumption data was conducted, evaluating 17
PV system configurations. The F-TOPSIS method was applied to rank these alternatives based on fuzzy-weighted criteria of power generation and budget limitations. Results indicate that the optimal configuration—utilizing 230 panels arranged across 10 MPPTs— achieves a balanced trade-off between performance and cost, delivering 129.6 kWp at a capital cost of RM334,025. The study demonstrates the effectiveness of the fuzzy decision making approach in handling uncertainties in multi-criteria PV system design and provides a systematic methodology for selecting the most viable solar PV configuration
Crafting a Comprehensive Interview Guide for Malaysian Parents in Sexuality Education : Methodological Insights and Best Practices
No full textIntroduction: Establishing a robust interview protocol is crucial for acquiring high-quality interview data, yet crafting such a protocol poses challenges, particularly for novice researchers and in sensitive areas like sexuality education. In the exploration of sexuality and reproductive health education, researchers encountered difficulties in posing questions to parents with diverse ethnic and sociodemographic backgrounds. Methods: This article illustrates the application of the 4-step Interview Protocol Refinement (IPR) Framework to the interview questionnaire, involving steps such as (1) aligning questions with research objectives(2) constructing inquiry-based conversations, (3) seeking feedback on protocols, and (4) pilot testing questionsIn this research, the participants were Malaysian parents with adolescents. Results: The IPR framework proves effective in enhancing the reliability and validity of the interview protocol. Two expert panels rectified deficiencies in the initial questionnaires through refinement processes and four parents involve in the validation phase through pilot testing Conclusion: The IPR framework greatly enhanced the reliability and validity of the interview protocol by iteratively refining questions. Further improvements in research quality can be achieved by implementing additional strategies during the stages of research tool validation and data analysis