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The purpose of this paper is to discuss the dispersion capacity and tribological behavior of liquid paraffin added by diamond nanoparticles.

The structure of the modified diamond nanoparticles which are prepared by oleic acid (OA) is observed by scanning electron microscopy (SEM) and infrared spectroscopy (IR). The dispersivity of these nanoparticles in liquid paraffin is measured by nanoparticle analyzer. The tribological behavior of adding diamond nanoparticles in liquid paraffin is evaluated by using a ball‐on‐ring wear tester.

The measurement results reveal the dispersion capability of OA modified diamond nanoparticles and indicate the dispersing stability in liquid paraffin of the OA which is bonded to the surface of diamond nanoparticles through esterification. It is found from wear testing results that the diamond nanoparticle as additive in liquid paraffin at proper concentration shows better tribological properties for anti‐wear (AW) and antifriction than the pure paraffin oil and different AW ability depending on the particle size.

It is shown in the paper that by reducing friction and AW, the lubricant prepared by the methods described can prolong operating hours of machinery.

The purpose of this paper is to study the dispersion and tribological properties of liquid paraffin with aluminum nanoparticles as additive, which are prepared by the surface‐modification method using oleic acid (OA).

The dispersion stability of aluminum nanoparticles in liquid paraffin is measured by spectrophotometry, which can be optimization by Taguchi method. The tribological properties are evaluated by using a ball‐on‐ring wear tester.

The results show that few concentrations of aluminum nanoparticles as additives in liquid paraffin have better antiwear and antifriction properties than the pure paraffin oil. Scanning electron microscopy and energy dispersive spectrometer analyses can show that the thin films on the rubbing surfaces can be formed by these aluminum nanoparticles, which not only bear the load but also separate the both interfaces, thus the wear and friction can be reduced.

Machine components and mechanism pairs rely on high‐quality lubricants to withstand high temperature and extreme pressure. Extreme pressure and antiwear additives are typically adopted to improve the tribological performance of a fluid lubricant in reducing friction and surface damage under severe conditions.

This paper is the third part of a serial studies for constant and variable compensations of the closed-type hydrostatic thrust bearings which has face-to-face recesses couple. The static stiffness of closed-type hydrostatic thrust bearings can then be obtained from the differentiation of recess pressure with respect to worktable displacement. The paper aims to discuss these issues.

In this paper, the double-action restrictors of cylindrical-spool-type and tapered-spool-type are taken into consideration for variable compensation of hydrostatic bearings.

The static stiffness in thrust direction of hydrostatic bearing is determined by the flow continuity equations that are formulated by film flow and compensation flow for each recess, respectively. The type selection and parameter determination of the double-action spool-type restrictors can be obtained from finding results of this study for maximum stiffness in design of hydrostatic bearings.

This study reveals that the appropriate range of recess pressure ratio and design parameters of restrictors for the maximum stiffness can be obtained, the avoidance of negative stiffness is also provided.

Concrete gravity dams are important structures for flood control and hydraulic power generation, but they can be vulnerable to seismic activity due to ground movements that trigger crack propagation.

To better understand the factors that affect the stability of concrete gravity dams against concrete fracture during earthquakes, a concrete plastic damage model has been utilized with two new expressions to simulate compressive and tensile damage variables.

The findings showed that the crack patterns were strongly influenced by the concrete’s strength. The simulation results led to the proposal of appropriate concrete properties aimed at minimizing damage. These findings, together with the proposed model, offer significant insights that can enhance the safety and stability of concrete gravity dam structures.

This study offers a comprehensive analysis of concrete behavior under varying grades and introduces simple and robust expressions for evaluating concrete parameters in plastic damage models. The versatility of these expressions enables accurate simulation of stress-strain curves for different grades, resulting in excellent agreement between model results and experimental findings. The simulation of the Koyna Dam case study demonstrates a similarity in crack patterns with previous simulations and field observations.