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For oil film thickness measurement using ultrasonic spring model, obtaining the isolated reflection from the oil film layer is the key point. While for oil film thickness measurement in thrust bearings with thin liner, the reflection from the substrate-Babbitt interface will overlap with the reflection from the oil film layer. This overlapping will render the ultrasonic spring model invalid. To obtain the isolated reflected signal from the oil film layer accurately, an adaptive method was developed to recover the overlapping echoes.

A genetic-algorithm-based support matching pursuit (GA-based SMP) was developed to provide the optimal echo number and initial parameters guesses automatically and efficiently. Then, the traditional expectation maximization (EM) model was used to fine tune the accurate results.

The developed method was tested using both simulated echoes and the overlapping echoes encountered in the ultrasonic oil film thickness measurement of thrust bearings. The results demonstrated that the developed method performed well on recovering overlapping echoes adaptively.

The work shows an adaptive method to recover the ultrasonic overlapping echoes. When used in ultrasonic oil film thickness measurement, it can help extend the application of traditional ultrasonic spring model to objects with four or more layers.

This study aims to characterize the lubrication condition under sliding-rolling contact using three indicators, including the oil film thickness and two perpendicular (vertical and tangential) vibrations. The lubrication deterioration can then be detected when sliding occurs in rolling contact.

An experimental study is presented to identify the lubrication deterioration under sliding-rolling contact. Sliding-rolling experiments with controlled loads, slip ratios and speeds are carried out on a roller-ring test rig. The deterioration of lubrication condition is analyzed by the transient oil film thickness and two perpendicular vibration signals, respectively.

The oil film thickness and the vibration signal play different roles in characterizing different lubrication deterioration conditions. Specifically, the degree of lubrication deterioration with slight solid-contact is indicated by the rapid reduction in oil film thickness. The degree of lubrication deterioration with severe solid-contact is reflected by two perpendicular (vertical and tangential) vibrations. Furthermore, the tangential vibration can indicate the occurrence of sliding in rolling contact.

A full characterization of the lubrication deterioration under sliding-rolling contact can be accomplished by integrating both the oil film thickness and two perpendicular vibration monitoring.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2024-0244/

The piston ring-cylinder liner pair is one of the most important tribological systems of an internal combustion engine. The friction loss of the piston ring-cylinder liner pair accounts for the largest portion of total efficiency losses. Therefore, improving the tribological system design of the piston ring-cylinder liner pair can reduce friction losses and bring tremendous economic benefits to society. This paper aims use surface texturing, which is proving to be an effective method, for improving the tribological performance of sliding surfaces.

In this paper, an experimental study using a pin-on-disk tribometer was carried out to evaluate the effects of surface texturing on friction reduction of piston rings under various loads and sliding velocities. Rectangular- and circular-shaped textures with different depths and area densities were produced by a Femtosecond laser. Comparison experiments were conducted with un-textured rings.

The results indicate that the friction performance of the ring surface was significantly improved by surface texturing, and the running-in stage was also shortened. More specifically, it was found that the rectangular-shaped texture had a better effect on friction reduction than the circular-shaped texture. Results also indicate that an optimum texture density existed for the rectangular-shaped texture. Additionally, it was observed that the average friction coefficient reduction of the textured ring decreased with increasing load and increased with increasing sliding velocity.

Consequently, these findings provide a more in-depth understanding of the relationship between micro-textures and tribological properties of piston rings in lubricating sliding.

This paper explores how the student movement in Taiwan transformed after the abolition of martial law. After democratization, there were three large-scale student protests, in 1990, 2008 and 2014. This paper explores the development through this period of student movement organizations, issues and interrelations between organizations and individuals.

The study of the process of transformation and development is based on an analysis of newspaper and magazine articles and books about the student movement. To provide an insider's view, magazines, statements and meeting memos written by activists are also included.

As a legacy of the student movement in the 1980s, the 1990 Wild Lily protest advocated democratization and organized a cross-school alliance. This pattern declined, however, because it proved hard to recruit participants after democratization. Instead, student activists returned to education-related issues, and the scale of student organizations remained small. The 2008 Wild Strawberry protest was carried out by autonomous, self-organized groups, which reflected the emergence of individuals as activists. Afterward, student movement organizations attempted to create multiple networks consisted of various issues and participants. These groups built solidarity by cooperating on education and political issues and became the base for the 2014 Sunflower protest.

This paper explores the rarely described historical context for the student movement between large-scale student protests in Taiwan and provides a more comprehensive understanding of the interrelation of organizations and individuals in contemporary social movements.

The purpose of this paper is to show the development of an image processing-based portable equipment for an automatic wear debris analysis. It can analyze both the qualitative and quantitative features of machine wear debris: size, quantity, size distribution, shape, surface texture and material composition via color.

It comprises hardware and software components which can take debris in near real-time from a machine oil sump and process it for features diagnosis. This processing provides the information of the basic features on the user screen which can further be used for machine component health diagnosis.

The developed system has the capacity to replace the existing off-line methods due to its cost effectiveness and simplicity in operation. The system is able to analyze debris basic quantitative and qualitative features greater than 50 micron and less than 300 micron.

Wear debris basic features analysis tool is developed and discussed. The portable and near real-time analysis offered by the discussed work can be more technically effective as compared to the existing off-line and online techniques.

In order to explore the damage probability of bridge engineering in the event of earthquake in the construction stages, the analysis method of seismic vulnerability in the construction stages is proposed in this paper.

Based on the joint simulation function of construction stage conditions and seismic response conditions of MIDAS/Civil finite element analysis software, combined with the method of IDA analysis and compared the relationship between demand and capacity.

The research shows that: (1) the average seismic loss in different construction stages varies greatly; (2) the seismic vulnerability varies greatly in different construction stages. The vulnerability of the bridge in stage 6 is determined by the longitudinal direction of bridge. Therefore, during the construction of the whole bridge, we should focus on strengthening the disaster and loss prevention strategy of earthquake insurance in the longitudinal direction of bridge. (3) The application of the secondary dead load mainly affects the fragilityin the longitudinal direction of bridge, but has little effect on the fragility in the transversal direction of bridge.

This paper is to explore the seismic vulnerability of a typical simply supported continuous bridge during the construction stages, and to trace the entire construction stage of a typical simply supported continuous bridge. According to the characteristics of the system transformation in the actual construction steps, demand-capacity ratios were established based on incremental dynamic analysis (IDA) and performance indicators of moment curvature and stability, and the seismic vulnerability research is carried out for the construction stages prone to earthquake damage. Furthermore, it provides a basis for seismic risk assessment of such bridges in different construction stages.