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This paper aims to investigate the effects of low-viscosity and ultralow-viscosity engine oils on the comprehensive friction and fuel economy of turbocharged gasoline direct injection (TGDI) through simulation analysis and experiments.

Numerical analysis models of friction loss for reciprocating, crankshaft and valve train are established. Based on the FAST, the friction loss of 24 specific parts of a TGDI engine was analyzed. Finally, the engine test bench was built, which was used to test the mechanical loss, external characteristics and universal characteristics.

Compared with the baseline oil, lower viscosity lubricating oil can reduce the friction loss of nine components to varying degrees. When the viscosity decreases, the friction distribution ratio of reciprocating, crankshaft and balance shaft will gradually decrease. The proportion of reciprocating when using 0W12 is reduced by 4%. Tests have shown that ultralow viscosity engine oil reduces torque loss by up to 15.74% (2,000 rpm, full throttle), but its fuel consumption rate becomes higher in low-speed and high-torque conditions.

This work helps to understand the effect of lubricating oil characteristics on the comprehensive friction performance of the engine.

This paper aims to investigate the influence of various laser texture parameters (diameter of pit, depth of pit and area density) on the tribological and tribo-vibration characteristics of tapered roller bearings (TRBs) under full oil lubricate conditions.

The laser surface texture parameters include: the diameter of pit (D: 60 µm, 100 µm, 200 µm), the depth of pit (H: 5 µm, 10 µm, 20 µm) and the area density (S: 6%, 12%, 24%). The outer raceway used laser marking device to prepare many regular pits. The tribological and tribo-vibration characteristics of pitting laser textured TRBs under full oil lubrication were studied by using the MMX-1A universal wear tester machine and vibration testing equipment. Through experiment and analysis, the effects of raceway pitting textures on tribological and tribo-vibration noise performance of TRBs were summarized.

When pit-textured TRBs operate under full oil, compared with the non-textured bearings, the average coefficient of friction and wear amount are significantly reduced. When D = 100 µm, H = 10 µm, S = 12%, average coefficient of friction = 0.00195 and wear amount = 0.12 mg, they are all at their minimum values. Compared to the same condition of non-textured groups, the coefficient of friction decreases by 66.6%, and the wear amount decreases by 79.3%. The energy from time-frequency and power spectrum analyses is mainly concentrated at high frequencies, with the signal power of pitting textured groups being lower than non-textured when the Y-direction is around 3600 Hz.

The experimental work can provide a reference for the investigation on the pitting textured TRBs.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0357/

This paper aims to analyze the frictional performance of the phosphated CTRBs under dry sliding conditions. Through friction and wear experiments and characterization analysis, this paper investigated the wear mechanism and anti-wear mechanism of the composite phosphating coatings.

This paper used a method of incorporating graphite particles and polytetrafluoroethylene (PTFE) particles into manganese-based phosphating solution to prepare composite phosphating coatings applied on cylindrical thrust roller bearings (CTRBs).

The results are as follows: the inclusion of functionalized graphite particles affects the characterization of the composite phosphating coatings, whereas PTFE particles serve a physical filling role and have no influence on the surface features of the composite phosphating coatings. The surface roughness of the composite phosphating coatings is the main factor affecting the frictional behavior of phosphated CRTBs. Roughness affects the amount of PTFE particles adsorbed on the surface of the phosphate crystals. PTFE particles can form a solid lubricating film at the friction interface, and under the same surface roughness conditions, phosphated CTRBs with added PTFE particles can improve its friction performance.

The characterization parameters of the composite phosphating coatings were controlled by adding functionalized graphite particles to the phosphating solution. The effects of adding only graphite particles and adding both graphite particles and PTFE particles on the surface characteristics of the phosphating coatings were discussed separately. The tribological performance of phosphating CTRBs was analyzed through friction and wear testing, and the influence of surface characteristics on wear mechanisms and anti-wear mechanisms was discussed.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2024-0405/

The purpose of this paper is to reveal the friction and wear performance of grooves textured cylindrical roller thrust bearings with different groove dimensions under starved lubrication.

The groove dimensions include: width of grooves (WOG, 50 µm, 100 µm and 150 µm), depth of grooves (DPOG, 7 µm, 11 µm and 15 µm) as well as groove deflection angle (GDA, 45°). A fiber laser marking system was used to prepare groove patterns on the raceways of shaft washers. The friction and wear properties of grooves textured bearings were researched through a vertical universal wear test rig using a customized roller bearing tribo-pair under starved lubrication. Static finite element analyses were conducted to reveal their surface stresses. Through the comprehensive comparison and analyses, the influence mechanism of grooves on the tribological behavior of cylindrical roller thrust bearings was proposed and discussed.

When grooves textured bearings run under starved lubrication, their average coefficients of friction (COFs) and wear losses are all significantly reduced and much lower than those of smooth group. The influence of DPOG on the COF curves is significant, while the influence of WOG on the COF curves is a little weak. The influence of groove dimensions on the surface stresses of grooves textured bearings is weak, whether the WOG or DPOG. In this work, when the WOG is 100 µm and the DPOG is 15 µm, its average COF and wear loss are both the lowest, 0.0066 and 0.61 mg, respectively. Compared with the data of smooth group, its friction coefficient is reduced by 75.3% and its mass loss is reduced by 95.8%, showing a significant improvement in this condition.

This work can provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

The purpose of this study is to achieve accurate matching of new process cases to historical process cases and then complete the reuse of process knowledge and assembly experience.

By integrating case-based reasoning (CBR) and ontology technology, a multilevel assembly ontology is proposed. Under the general framework, the knowledge of the assembly domain is described hierarchically and associatively. On this basis, an assembly process case matching method is developed.

By fully considering the influence of ontology individual, case structure, assembly scenario and introducing the correction factor, the similarity between non-correlated parts is significantly reduced. Compared with the Triple Matching-Distance Model, the degree of distinction and accuracy of parts matching are effectively improved. Finally, the usefulness of the proposed method is also proved by the matching of four practical assembly cases of precision components.

The process knowledge in historical assembly cases is expressed in a specific ontology framework, which makes up for the defects of the traditional CBR model. The proposed matching method takes into account all aspects of ontology construction and can be used well in cross-ontology similarity calculations.

This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments.

The electrochemical corrosion behavior of bulk nanocrystalline (NC) copper prepared by inert gas condensation and in situ warm compress technique was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy tests in de-aerated 0.1 M NaOH solution.

NC copper exhibited a typical active-passive-transpassive behavior with the formation of duplex passive films, which was qualitatively similar to coarse-grain (CG) copper. Although a compact passive film formed on NC copper surface, the corrosion resistance of NC copper was lower in comparison with CG copper. The increase in corrosion rate for NC copper was mainly attributed to the high activity of surface atoms and intergranular atoms. These atoms led to an enhancement of passive ability and an increase of dissolution rate of passive film in oxygen-deficiency solution. For NC copper, the corrosion resistance decreased as grain size increased in NC range.

The difference in corrosion resistance between bulk NC copper and its CG counterpart is dependent upon the corrosion solution. In a previous work, the potentiodynamic polarization tests revealed that NC copper bulks (grain size 48, 68, 92 nm) had identical corrosion resistance to CG copper bulk in naturally aerated 0.1 M NaOH solution. The results might be related to the dissolved oxygen in the medium.

The publication presents an analysis of the cost and schedule performance of incentive/disincentive projects and case studies toward developing a systematic disincentive valuation process, with Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) software integration that aids agencies in minimizing the likelihood of court challenges of disincentives.

From a California transportation database, the authors performed cost and schedule analyses of 43 incentive/disincentive (I/D) projects and case studies on four of those I/D projects. Interviewees included subject matter experts from transportation organizations to ensure applicability and maximum value-adding, and the process was implemented on ten California transportation projects and monitored for performance.

The presented process mitigates the contractor's ability to claim disincentives as penalties in a court of law through the following: (1) all calculations are performed using project-specific bases, backed by estimations of actual incurred costs; (2) the CA4PRS software allows for estimation transparency and (3) the clarity of cost inclusions reduces any chances of “double-dipping” between disincentives and liquidated damages.

Transportation agencies have historically faced legal challenges to their enforcements of disincentives. As agencies continue to apply disincentives on more megaprojects, contractors will likely attempt to pursue legal challenges more frequently. The presented process mitigates the likelihood of these challenges going to court and increases the accuracy and efficiency of disincentives.

While there have been publications that discuss the legal challenges of imposing disincentives, they mainly provide guidelines and lack applicable processes. Existing literature that does present incentive/disincentive valuation process focuses on incentive valuations and neglects the disincentives' legal challenges. The following publication fills this gap by presenting an applicable disincentive valuation process for transportation projects which incorporates the guidelines for legal mitigation.

This paper aims to comprise the new ideas for the efficient implementation to autonomous mobile robot navigation over the complex environment in presence of static obstacles.

The fuzzy decision via probability and its distribution is applied for the generating objective function subject to the robotics path and obstacle avoidance. The present objective function is formed to achieve high level of significance for the real-time obstacle avoidance and the efficiency.

The proposed controller makes a robot take its decision effectively in complex environment in a feasible time. In comparison with other AI approaches the proposed controller reflects that the proposed method outperforms in terms of optimal path and quality of solution. The experimental and simulation results are nearly same.

It has been tested in a complex crowded environment to find shorter path than existed approaches. For the validation, the experimental and simulation result using Matlab Software (R2008) has provided at the end of the paper.