Search results

The purpose of this paper is to study the engineering application of diamond like carbon (DLC) coatings on the surfaces of piston pins and bucket tappets for a 2.0 L supercharged gasoline engine. The friction loss and durability of DLC-coated components were investigated.

The tribological characteristics were examined under oil-lubricated conditions in a CETR UMT reciprocating tribometer. In a motored engine test rig, friction loss torque test was performed to estimate the improvement in fuel economy. Fired engine durability bench tests of typical duration of 450 h were completed to access the durability and wear resistance of DLC coating. Before and after durability tests, coated and uncoated components were measured on the sliding surface by a profilometer technique.

Friction and wear test results show that DLC coating has low friction coefficient and reduces the wear rates by almost ten times compared to those of uncoated surfaces. Friction loss measurements indicate that DLC-coated tappets can reduce valve train friction loss by 29 per cent, and DLC-coated piston pins can reduce piston group friction by 11 per cent. Based on fired engine durability bench tests, it is evidenced that none of the coated tappets and pins show any noticeable peeling or delamination. Wear profiles analysis results indicate that DLC-coated engine components give rise to a substantial reduction in wear.

DLC coating applied onto the working surface of piston pin and bucket tappet can effectively reduce the friction loss of gasoline engine. DLC coating exhibits sufficient durability and improves friction and wear performance.

This chapter highlights the characteristics of Asia through the analysis of policy-related documents by five donor countries, namely Japan, South Korea, China, India and Thailand. It will also examine the roles played by regional bodies such as the Southeast Asian Ministers of Education Organization (SEAMEO) and ASPBAE (the Asia South Pacific Association for Basic and Adult Education) as the horizontal channels influencing aid policies in respective countries. Together with the analysis of the national and organizational policies, the regional process of building consensus on the post-2015 agenda is examined, with a particular focus on the Asia-Pacific Regional Education Conference (APREC) held in August 2014.

The analysis reveals that the region has two faces: one is imaginary and the other is functional. There is a common trend across Asian donors to refer to their historical ties with regions and countries to which they provide assistance and their traditional notions of education and development. They highlight Asian features in contrast to conventional aid principles and approaches based on the Western value system, either apparently or in a muted manner. In this sense, the imagined community of Asia with common cultural roots is perceived by the policymakers across the board.

At the same time, administratively, the importance of the region as a stage between the national and global levels is recognized increasingly in the multilateral global governance structure. With this broadened participatory structure, as discussed in the chapter ‘Post-EFA Global Discourse: The Process of Shaping the Shared View of the ‘Education Community’’, the expected function of the region to transmit the norms and requests from the global level and to collect and summarize national voices has increased.

Human-induced marine environmental noise, such as commercial shipping and seismic exploration, is concentrated in the low-frequency range. Meanwhile, low-frequency sound signals can achieve long-distance propagation in water. To meet the requirements of long-distance underwater detection and communication, this paper aims to propose an micro-electro-mechanical system (MEMS) flexible conformal hydrophone for low-frequency underwater acoustic signals. The substrate of the proposed hydrophone is polyimide, with silicon as the piezoresistive unit.

This paper proposes a MEMS heterojunction integration process for preparing flexible conformal hydrophones. In addition, sensors prepared based on this process are non-contact flexible sensors that can detect weak signals or small deformations.

The experimental results indicate that making devices with this process cannot only achieve heterogeneous integration of silicon film, metal wire and polyimide, but also allow for customized positions of the silicon film as needed. The success rate of silicon film transfer printing is over 95%. When a stress of 1 Pa is applied on the x-axis or y-axis, the maximum stress on Si as a pie-zoresistive material is above, and the average stress on the Si film is around.

The flexible conformal vector hydrophone prepared by heterogeneous integration technology provides ideas for underwater acoustic communication and signal acquisition of biomimetic flexible robotic fish.

45 steel is a common material for the manufacture of various components such as shafts or gears. However, its poor surface properties often limit its applications. The purpose of this paper is to find a way to enhance the surface performance of 45 steel, which is expected to improve the wear resistance of 45 steel.

Double glow plasma surface metallurgy technique was used to prepare hafnium carbide (HfC) coatings on the surface of the 45 steel with two preparation process; one is to diffuse two elements together, while the other is to diffuse step by step. The scanning electronic microscopy and the X-ray diffraction were used to analyze the morphology and phase of the HfC coatings. And then the wear tests were carried out for this coating.

Coating diffused step by step shows better performance; it has a 15-µm alloyed layer which is uniform and dense and its hardness can reach up to 1326.5 Vickers-hardness (HV). While the coating fabricated by diffusing elements together owns a 10-µm alloyed layer and its hardness is 1204.1 HV. According to the wear test results, both coatings have a protective effect on the substrate and the coating prepared by step-by-step diffusion process has less wear volume, indicating that it possesses better friction reduction.

A new method which diffuses elements together was successfully used to prepare compound HfC coating, which can reduce the cost of coating preparation and improve the efficiency of coating preparation.

The purpose of this study is to prepare WC-10Co-4Cr coatings using two processes of plasma spraying and high-velocity oxygen fuel (HVOF) spraying. The decarburization behaviors of the different processes are analyzed individually. The microstructural characteristics of the as-sprayed coatings are presented and the wear mechanisms of the different WC–10Co–4Cr coatings are discussed in detail.

The WC–10Co–4Cr coatings were formed on the surface of Q235 steel by plasma and HVOF spraying.

Plasma spraying causes more decarburizing decomposition of the WC phase than HVOF spraying. In the plasma spraying process, η(Cr25Co25W8C2) phase appears and the C content decreases from the top surface of the coating to the substrate.

In this study, two WC–10Co–4Cr coatings on Q235 steel prepared by plasma and HVOF spraying were compared with respect to the sliding wear behavior.

The wear mechanisms of the plasma- and HVOF-sprayed coatings were abrasive and oxidation, respectively.

Social media facilitates consumer exchanges on product opinions and provides comprehensive knowledge of online products. The interaction between consumers and e-retailers evolves into a collective set of dynamics within a complex system. Agent-based modeling is well suited to stimulate such complex systems. The purpose of this paper is to integrate agent-based model and technique for order performance by similarity to ideal solution (TOPSIS) to simulate decision behaviors of e-retailers in competitive online markets.

An agent-based network model using the TOPSIS driven by actual price data is developed. The authors ran an experimental model to simulate interactions between online consumers and e-retailers and to record simulation data. A nonparametric test is used to conduct data analysis and evaluate the sensibility of parameters.

Simulation results showed that different profits could be obtained for various brands under different social network structures. E-retailers could achieve more profits through cross-selling than single-selling; however, the highest profits can be achieved when some adopt cross-selling, whereas others use single-selling. From a game perspective, the equilibrium for price-adjustment frequency can be determined from the simulation data. Thus, price adjustment differences significantly affect e-retailer profit.

This study provides new insights into the evolutionary dynamics of online markets. This work also indicates how to build an integrated simulation model with an agent-based model and TOPSIS and how to use an integrated simulation model and interpret its results.

The purpose of this study is to undertake an evaluation of the resilient capacity of the infrastructure systems in the city of Wuhan. This evaluation focuses on the ability of the infrastructure to cope with extreme weather from multiple dimensions and to propose effective interventions against such risks.

This research draws on a review and synthesis of the theory of resilience and adopts the literature induction method to build an evaluation index for five urban systems, namely: roads; water supply and drainage; energy and power; urban disaster reduction; and communications. Index data from the period of 1990–2019 are combined with the views of experts from Wuhan and analyzed using principal component analysis (PCA) to calculate the weightings of the five urban systems. A fuzzy comprehensive evaluation method is then used to investigate the resilient capacity of these five urban infrastructure systems in the city.

Generally, the results show that the resilience of the infrastructure systems in Wuhan are at a high level. Based on the results, the communications and roads systems are found to have higher levels of resilience, while the disaster mitigation system is found to have a relatively low level of resilience. Recommendations are suggested to help improve resilience and prioritize investments in the development of the city's infrastructure systems.

The development of these specific indicators and quantitative requirements have not been studied in detail, so a more comprehensive, systematic evaluation of quantitative indicators and methods of urban infrastructure resilience is still required. In addition, the research on the resilience of urban infrastructure under extreme weather is still in its infancy, and it is essential to further increase the quantitative assessment of the resilience of urban infrastructure under construction. This will also be indispensable information in the subsequent implementation of a resilient planning process.

This research builds a rigorous and reliable evaluation model that avoids any subjective bias in the results and represents a new approach to evaluate the resilience of the infrastructure systems in the city of Wuhan, which could be applied to other cities.

This paper aims to clarify the resistance degree of group road logistics to flood disaster resilience. The paper measures the resilience of group road logistics by establishing network structure model. The purpose of this study is to improve the resilience of road log.

This paper adopts Delphi method to collect data, interviews mainly flood management experts and supply chain risk management experts, and then analyzes the data through the network structure model combined with interpretative structure model (ISM) and analytical network process (ANP).

The results show that flood frequency and drainage systems are the main factors affecting the resilience of road transport logistics in urban areas. These research results provide useful guidance for the effective planning and design of urban road construction and infrastructure.

However, the main factors affecting the resilience of road transport logistics are likely to change with the development of factors such as climate, economy and environment. Therefore, in future work, the authors' research will focus on the further application of this evaluation method.

The results show that the impact of flooding on the four dimensions of road logistics resilience varies. This shows that in deciding what intervention measures are to be taken to improve the resilience of the road network to flooding, various measures need to be considered.

This paper provides a more scientific analysis of the risk management ability of the road network in the face of floods. In addition, it also provides a useful reference for urban road planners.

This paper addresses a clear need to study how to build models to improve the resilience of road logistics in flood risk.

This study aims to determine the key indicators affecting the resilience of the construction supply chain to flooding and calculate the resilience of the urban construction supply chain in three cases city.

This study combines expert opinions and literature review to determine key indicators and establish a fuzzy EWM-GRA-TOPSIS evaluation model. The index weight was calculated using the entropy weight method, and GRA-TOPSIS was used for comprehensive evaluation.

The results of the study show that the three cities are ranked from the high to low in order of Hangzhou, Hefei and Zhengzhou.

The innovative method adopted in this study comprising EWM-GRA-TOPSIS reduced the influence of subjectivity, fully extracted and utilized data, in a way that respects objective reality. Further, this approach enabled the absolute and relative level of urban construction supply chain resilience to be identified, allowing improvements in the comprehensiveness of decision-making. The method is relatively simple, reasonable, understandable, and computationally efficient. Within the approach, the entropy weight method was used to assign different index weights, and the GRA-TOPSIS was used to rank the resilience of the construction supply chain in three urban cities. The development of resilience provides a robust decision-making basis and theoretical reference, further enriching research methods, and having strong practical value. The study serves to improve risk awareness and resilience, which in turn helps to reduce losses. It also provides enhanced awareness regarding the future enhancement of supply chain resilience for urban construction.

The purpose of this paper is to obtain the optimal N₂/Ar ratio parameters for preparing Ta (C, N) coating. Three coatings with different N₂/Ar ratios were prepared on the TA15 substrate, and their effects on the wear properties of the coatings were discussed.

Ta(C, N) coatings with three different N₂/Ar ratios were prepared on TA15 substrates using the double cathode glow metallurgical plasma alloying technique (DGMPA) using a step-by-step diffusion method.

With the increase of N₂/Ar flow ratio, the hardness and elastic modulus of the coating first increase and then decrease. Compared with the S1 sample (N₂/Ar gas ratio 25: 75) and the S3 sample (N₂/Ar gas ratio 75: 25), the S2 sample (N₂/Ar gas ratio 50: 50) has better mechanical properties, with hardness increased by 48.45% and 6.8%, respectively, and elastic strain ratio increased by 22.8% and 28.5%, respectively. Moreover, the wear degree of the S2 sample is less than other samples. The wear rate of the S2 sample was 32.4% lower than the S3 sample at 300°C and 14.3% lower than the S3 sample at 500°C. Therefore, the S2 sample has the best mechanical properties and the best high temperature wear resistance.

Ta(C, N) coatings were prepared by DGMPA technology, and the wear mechanism of Ta(C, N) coatings with different N₂/Ar ratios was investigated to reduce the wear rate.