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Hydroelectric power is widely used because it is environmental friendly, renewable and green. The cavitation is an inevitable phenomenon during the operation of hydro turbine, which is related to the efficiency and service life of the unit. This paper aims to discriminate the phenomenon of the incipient cavitation, prevent the early destruction and avoid the irreversible damage to hydro turbine.

The paper tries to find out the characteristics of cavitation entirely through a variety of features. The method comprises collection of the signals using a hydrophone, acceleration sensor and acoustic emission sensor; analyzing cavitation signal by using the way of wavelet time-frequency, peak factor and power spectral density; and comparing the different wavelet basis for analyzing signals and find the most suitable one.

The analyzed results show that the wavelet basis of morlet is more suitable for the cavitation signals. The hydrophone can distinguish the different operating conditions and discriminate the difference between the phenomenon of incipient cavitation and the other state of cavitation. The results show that when the hydrophone and acceleration sensors are used, the accuracy rate goes up to 75 per cent, which meets the requirements for the detection for incipient cavitation.

This paper focuses on finding the best sensor to discriminate the operating state of incipient cavitation to prevent early destruction.

Dynamically tracking the target by unmanned ground vehicles (UGVs) plays a critical role in mobile drone recovery. This study aims to solve this challenge under diverse random disturbances, proposing a dynamic target tracking framework for UGVs based on target state estimation, trajectory prediction, and UGV control.

To mitigate the adverse effects of noise contamination in target detection, the authors use the extended Kalman filter (EKF) to improve the accuracy of locating unmanned aerial vehicles (UAVs). Furthermore, a robust motion prediction algorithm based on polynomial fitting is developed to reduce the impact of trajectory jitter caused by crosswinds, enhancing the stability of drone trajectory prediction. Regarding UGV control, a dynamic vehicle model featuring independent front and rear wheel steering is derived. Additionally, a linear time-varying model predictive control algorithm is proposed to minimize tracking errors for the UGV.

To validate the feasibility of the framework, the algorithms were deployed on the designed UGV. Experimental results demonstrate the effectiveness of the proposed dynamic tracking algorithm of UGV under random disturbances.

This paper proposes a tracking framework of UGV based on target state estimation, trajectory prediction and UGV predictive control, enabling the system to achieve dynamic tracking to the UAV under multiple disturbance conditions.

The kindergarten curriculum in mainland China has evolved through four periods and the current reform began in the end of 1980s. The reform aimed to transform kindergarten practice by shaping ideologies including respect for individual child, active learning, and play-based integrated curriculum. This review of research literatures shows that compared with the practice before the reform, many kindergarten teachers organize classrooms in learning centers, provide more play materials, pay time, and freedom for free play, and pay more attention to individuals. But indoor space organized in rice-seedling-bed model, teacher-led group instruction and teacher-controlled interactions are still often observed after three decades of reform efforts; there still exist great variations among kindergartens of different sponsoring bodies and in different regions. The problems resulted from the innate deficiencies of the top-down and value-priority reform, the conflicts between the advocated value and the traditional Chinese culture with emphasis on Ming-Fen, testing, and the value of children for the whole family and nation, and the unequal distribution of public resources decided by the educational institutions. Therefore, the curriculum reform is not a separate endeavor from other social changes, but a comprehensive and systematic change. To guarantee the success of the curriculum reform, the Chinese society needs cultural transformation and institutional reconstruction.

This paper aims to investigate Cu/SnAgCu/Cu transient liquid phase (TLP) bonding with different thicknesses for three-dimensional (3D) integrated circuit (IC).

This paper includes experiments and finite element simulation.

The growth rate of the intermetallic compound layer during TLP soldering was calculated to be 0.6 μm/s, and the small scallop-type morphology Cu₆Sn₅ grains can be observed. With the decrease in thickness in solder joint, the thickness of intermetallic compounds represents the same size and morphology, but the size of eutectic particles (Ag₃Sn, Cu₆Sn₅) in the matrix microstructure decrease obviously. It is found that with the increase in thickness, the tensile strength drops obviously. Based on finite element simulation, the smaller value of von Mises demonstrated that the more reliability of lead-free solder joints in 3D IC.

The Cu/SnAgCu/CuTLPbondingwithdifferentthicknessesfor3D IC was investigated.

Sustainable urban rail transit requires noise barriers. However, these barriers’ durability varies due to the differing aerodynamic impacts they experience. The purpose of this paper is to investigate the aerodynamic discrepancies of trains when they meet within two types of rectangular noise barriers: fully enclosed (FERNB) and semi-enclosed with vertical plates (SERNBVB). The research also considers the sensitivity of the scale ratio in these scenarios.

A 1:16 scaled moving model test analyzed spatiotemporal patterns and discrepancies in aerodynamic pressures during train meetings. Three-dimensional computational fluid dynamics models, with scale ratios of 1:1, 1:8 and 1:16, used the improved delayed detached eddy simulation turbulence model and slip grid technique. Comparing scale ratios on aerodynamic pressure discrepancies between the two types of noise barriers and revealing the flow field mechanism were done. The goal is to establish the relationship between aerodynamic pressure at scale and in full scale.

The aerodynamic pressure on SERNBVB is influenced by the train’s head and tail waves, whereas for FERNB, it is affected by pressure wave and head-tail waves. Notably, SERNBVB's aerodynamic pressure is more sensitive to changes in scale ratio. As the scale ratio decreases, the aerodynamic pressure on the noise barrier gradually increases.

A train-meeting moving model test is conducted within the noise barrier. Comparison of aerodynamic discrepancies during train meets between two types of rectangular noise barriers and the relationship between the scale and the full scale are established considering the modeling scale ratio.

Since the beginning of the 21st century, China’s outward foreign direct investment (OFDI) is growing steadily and Chinese multinationals (MNCs) are playing an increasingly important role in the global economy. Thus, the number of papers focusing on China’s OFDI and Chinese MNCs has been increasing during the last years. The aim of this chapter is to carry out a review of the empirical papers dealing with Chinese MNCs published between 2002 and 2012 in high-impact international business and management journals.

This chapter reviews 43 empirical papers focusing on Chinese MNCs that were published in nine major scholarly journals between 2002 and 2012.

We report individual and institutional contributions, the theories and methods used, the research topics, and the main findings. We also discuss implications for future research.

Some previous literature reviews have dealt with research on China’s OFDI and Chinese MNCs. Nevertheless, none of the earlier reviews dealt specifically with empirical papers; neither did they provide an analysis of both individual and institutional contributions.

The purpose of this paper is an attempt to design a proper incentive coordination mechanism to deal with the channel conflicts between the traditional sales and online direct sales.

With respect to the problems of channel conflicts between the traditional sales and online direct sales, to optimize the sale system and get more profits, considering the influences of consumer network acceptance, the authors establish demand and profit function based on consumer's utility, respectively. What's more, we exploit the game theory to analyze the optional decisions of the supply chain under the incentive coordination condition and no incentive coordination condition, and then we discuss the supply chain's optimal pricing, demand, profit and compensation incentive levels with the different effect of consumer network acceptance.

The level of compensation incentive provided by the manufacturer is influenced by consumer network acceptance and product cost. The lower the consumer network acceptance, the better the compensation incentive coordination effect of manufacturers. Manufacturers, wholesalers, retailers and consumers are all important players in real supply chain relationships. When a manufacturer exists as a dominant role, it should pay full attention to the impact of consumer behavior on supply chain decisions.

The research can clarify the influence and mechanism of consumer behavior on supply chain channel conflict coordination, and deal with channel conflicts.

The proposed incentive coordination can effectively realize supply chain channel conflict resolution, and provide decision-making ideas and methods for manufacturers to develop the supply chain management of online direct sales channels.

As the cost of completing a transaction, the green merger and acquisition (M&A) premium paid on mergers can influence whether the acquisition creates value or not. However, studies linking M&A premiums to firm value have had mixed results, even fewer studies have examined the effect of green M&A premiums on bidders’ firm value. The purpose of this paper is to investigate whether and how green M&A premiums affect firm value in the context of China’s heavy polluters.

Using 323 deals between 2008 and 2019 among China’s heavy polluters, this paper estimates with correlation analysis and multiple regression analysis.

Green M&A premiums are negatively associated with firm value. The results are more significant when firms adopt symbolic rather than substantive corporate social responsibility (CSR) strategies. Robustness and endogeneity tests corroborate the findings. The negative relation is stronger when acquiring firms have low governmental subsidy and environmental regulation, when firms have overconfident management, when firms are state-owned and when green M&A occurs locally or among provinces in the same region. This study also analyzes agency cost as an intermediary in the relationship between green M&A premium and firm value, which lends support to the agency-view hypothesis.

This study provides systemic evidence that green M&A premiums damage firm value through agency cost channel and the choice of CSR strategies from the perspective of acquirers. These findings enrich the literature on both the economic consequences of green M&A premiums and the determinants of firm value and provide a plausible explanation for mixed findings on the relationship between green M&A premiums and firm value.

Given the current friction and wear challenges faced by automobile parts and bearings, this study aims to identify a novel texture for creating anti-friction and wear-resistant surfaces. This includes detailing the preparation process with the objective of mitigating friction and wear in working conditions.

Femtosecond laser technology was used to create a mango-shaped texture on the surface of GCr15 bearing steel. The optimized processing technology of the texture surface was obtained through adjusting the laser scanning speed. The tribological behavior of the laser-textured surface was investigated using a reciprocating tribometer.

The friction coefficient of the mango-shaped texture surface is 25% lower than that of the conventional surface, this can be attributed to the reduced contact area between the friction ball and the micro-textured surface, leading to stress concentration at the extrusion edge and a larger stress distribution area on the contact part of the ball and disk compared to the conventional surface and the function of the micro-texture in storing wear chips during the sliding process, thereby reducing secondary wear.

The mango-shaped textured surface in this study demonstrates effective solutions for some of the friction and wear issues, offering significant benefits for equipment operation under light load conditions.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0127/