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Engineering components/structures with geometric discontinuities normally bear complex and variable loads, which lead to a multiaxial and random/variable amplitude stress/strain state. Hence, this study aims how to effectively evaluate the multiaxial random/variable amplitude fatigue life.

Recent studies on critical plane method under multiaxial random/variable amplitude loading are reviewed, and the computational framework is clearly presented in this paper.

Some basic concepts and latest achievements in multiaxial random/variable amplitude fatigue analysis are introduced. This review summarizes the research status of four main aspects of multiaxial fatigue under random/variable amplitude loadings, namely multiaxial fatigue criterion, method for critical plane determination, cycle counting method and damage accumulation criterion. Particularly, the latest achievements of multiaxial random/variable amplitude fatigue using critical plane methods are classified and highlighted.

This review attempts to provide references for further research on multiaxial random/variable amplitude fatigue and to promote the development of multiaxial fatigue from experimental research to practical engineering application.

The coal bed methane resources distribution of Handan - Fengfeng Mining area has the features of "richness in the midland and north while poorness in the south, and richness in the east while poorness in the west. Through the analysis of the geological factors causing the above phenomena, we get that: the coal metamorphism and hydrogeological condition are the major controlling factors, the former controls the north and south difference of coal bed methane resources distribution from the two aspects covering gas-generated quantity and adsorption capacity, while the latter controls the east and west difference of coal bed methane resources distribution; syncline and good cap rock conditions are necessary conditions for coal bed methane enrichment, but not the reason for causing the difference of coal bed methane resources distribution.

Sedimentary facies type of the Shanxi Formation in northeastern Ordos Basin is an ongoing debate. Based on field measurements, sample collection and identification, and laboratory analysis, we systematically evaluated the sedimentary characteristics of the sandstone bodies of Shanxi Formation of Chengjiazhuang section in Liulin. Analysis included identifying sample composition, grain size, texture, sedimentary structure and spatial distribution. We came to the conclusion that the sedimentary environment of Shanxi Formation is deltaic. This deltaic environment included deltaic front and deltaic plain. It can be further divided into five sedimentary microfacies: subfluvial distributary channel, subfluvial distributary interchannel, distributary channel, levee, and peat bog. And lastly, the evolution of sedimentary environment of Shanxi Formation is discussed.

In the high-speed trains (HSTs) production process, assembly sequence planning (ASP) problems is an extremely core issue. ASP problems influence the economic cost, amount of workers and the working time in the assembly process, seriously. In the design process of HSTs, the assembly sequence is usually given by experience, and the correctness of the assembly sequence is difficult to guarantee by experience and low effectiveness. The ASP based on improved discrete particle swarm optimization (IDPSO) algorithm was proposed to address these issues.

In view of the local convergence problem with basic DPSO in ASP, this paper presents an IDPSO, in which a chosen strategy of global optimal particle is introduced in, to solve the ASP problems in the assembly process of HSTs operation panel. The geometric feasibility, the assembly stability, and the number of assembly orientation changes of the assembly are chosen to be the optimization objective. Furthermore, the influences of the population size, the weight coefficient, and the learning factors to the stability and efficiency of IDPSO algorithm were discussed.

The results show that the IDPSO algorithm can obtain the global optimum efficiently, which is proved to be a more useful method for solving ASP problems than basic DPSO. The IDPSO approach could reduce the working time and economic cost of ASP problems in HSTs significantly.

The method may save the economic cost, reduce the amount of workers and save the time in the assembly process of HSTs. And also may change the method of ASP in design and manufacturing process, and make the production process in HSTs more efficiently.

A chosen strategy of global optimal particle is presented, which can overcome the local convergence problem with basic DPSO for solving ASP problems.

The social responsibility of a tourism destination results from the combined efforts of the single stakeholders. This needs coordination and harmonization that cannot be achieved without a deep understanding of the structural and dynamic characteristics of the destination. A tourism destination is a complex dynamic system and requires specific methods to be analyzed and understood in order to better tailor governance actions for steering it along an evolutionary growth path, respectful of the social responsibility towards the community. Many methodological recommendations exist that allow to assess these features, and some have been successfully applied to tourism destinations. This paper aims to explore a new proposal: the visibility graph algorithm (VGA), which is able to provide the required level of information in a fast and simple way.

VGA is a technique to map a time series into a network. The method and its implementation are relatively simple and straightforward. The mapping allows examining the system's properties by using network analytic methods. An example is worked out using data from two destinations: Italy as a country and the island of Elba, one of its most popular areas.

The complexity properties of the two destinations are examined and found in agreement with those obtained by using more complicated approaches, thus strengthening the reliability of the method.

This paper provides a new method to examine a tourism destination using a readily available set of data and a simple algorithm. The contribution of this work is mainly methodological. The technique provides insights into the complex structure and dynamics of a tourism destination. This has important implications for those interested in enriching the toolsets used to study a destination from a complex system perspective.

The Environmental Protection Bureau of Taiwan established the South Star Project in Kaohsiung, Taiwan, as a solution to two problems facing the city—the urgent need to dispose of industrial wastes and the need to increase land for the city. To embank land from the sea, breakwaters were constructed. The material used to construct breakwaters was a mixture of furnace slag (waste from the steel industry) and fly ash (waste from power plants). After constructing the breakwaters, the ‘reclaimed land’ was used as a landfill for construction and public waste. In the future, these reclaimed lands will be used for the development of a deepwater port or sea airport. Construction of breakwaters is a very repetitive process, and any improvements made would help contractors reduce the duration of the operation, improve efficiency in the process and thereby reduce costs. This paper discusses the process of breakwater construction and the utilization of industrial wastes for the concrete work on the project. Data collected from the first stage of the South Star Project is used in the modelling, simulation and analysis of the process, in order to examine the interaction between different resources.

The color painting of ancient buildings has high historical and artistic value but is prone to aging due to long-term outdoor exposure. The purpose of this study is to develop a new type of sealing coating to mitigate the impact of ultraviolet (UV) light on color painting.

The new coating was subjected to a 500-h UV-aging test. Compared with the existing acrylic resin Primal AC33, the UV aging behavior of the new coating, such as color difference and gloss, was studied with aging time. The Fourier infrared spectra of the coatings were analyzed after the UV-aging test.

Compared with AC33, the antiaging performance of SF8 was substantially improved. SF8 has a lower color difference value and better light retention and hydrophobicity. The Fourier transform infrared spectroscopy results showed that the C-F bond and Si-O bonds in the resin of the optimized sealing coating protected the main chain C-C structure from degradation during the aging process; thus, the resin maintained good stability. The hindered amine light stabilizer TN292 added to the coating inhibited the antiaging process by trapping active free radicals.

To address the problem of UV aging of oil-decorated colored paintings, a new type of sealing coating with excellent antiaging properties was developed, laying the foundation for its demonstration application on the surface of ancient buildings.

This paper aims to contrastively investigate the antioxidant behavior and tribological performance of a novel multifunctional additive (PBT) and dialkyldithiophosphate (ZDDP) in complex lithium grease (CLG).

PBT was successfully synthesized through esterification reaction. The antioxidant behavior of PBT and ZDDP was investigated by thermal analysis, and meanwhile, their tribological performance was evaluated by Optimol SRV-IV oscillating reciprocating friction and wear tester (SRV-IV test) and MRS-1J four-ball tester (Four-ball test). Furthermore, their anticorrosion ability was determined by copper strip corrosion test.

Four-ball tests showed that the extreme pressure property of PBT was a little inferior to that of ZDDP. Besides, all the other results demonstrated that PBT showed more superior antioxidation stability, friction-reduction and antiwear ability, as well as anticorrosion performance than ZDDP.

This work provides a study of hindered phenol derivative as a multifunctional additive in lubricant grease, which can contribute to the development of substitution of ZDDP.

The purpose of this study is to determine the cavitation flow characteristics of the high-pressure differential control valve. The relationship between cavitation, flow coefficient and spool angle is obtained. By analyzing the relationship between different spool angles and energy loss, the energy loss at different spool angles is predicted.

A series of numerical simulations were performed to study the cavitation problem of a high-pressure differential control valve using the RNG k–e turbulence model and the Zwart cavitation model. The flow states and energy distribution at different spool angles were analyzed under specific working conditions.

The cavitation was the weakest when the spool angle was 120° or the outlet pressure was 8 MPa. The pressure and speed fluctuations of the valve in the throttle section were greater than those at other locations. By calculating the entropy production rate, the reason and location of valve energy loss are analyzed. The energy loss near the throttling section accounts for about 92.7% of the total energy loss. According to the calculated energy loss relationship between different regions of the spool angle, the relationship between any spool angle and energy loss in the [80,120] interval is proposed.

This study analyzes the cavitation flow characteristics of the high-pressure differential control valve and provides the law of energy loss in the valve through the analysis method of entropy. The relationship between spool angle and energy loss under cavitation is finally proposed. The research results are expected to provide a theoretical basis for the optimal design of valves.

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.