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This paper aims to investigate the effects of inhomogeneities on the rolling contact fatigue (RCF) life in elastohydrodynamically lubricated (EHL) point contacts.

A numerical model for predicting the RCF life of inhomogeneous materials in EHL contacts was established by combining the EHL model and the inclusion model through the eigen-displacement and then connecting to the RCF life model through the subsurface stresses. Effects of the type, size, location and orientation of a single inhomogeneity and the distribution of multiple inhomogeneities on the RCF life were investigated.

The RCF life of a half-space containing manganese sulfide (MnS) inhomogeneity or the mixed inhomogeneity of aluminium oxide (Al₂O₃) and calcium oxide (CaO) was longer than that for the case of Al₂O₃ inhomogeneity. For a single ellipsoidal MnS inhomogeneity, increases of its semi-axis length and decreases of its horizontal distance between the inhomogeneity and the contact center shortened the RCF life. Furthermore, the relationship between the depth of a single MnS inhomogeneity and the RCF life was found. For the half-space containing multiple inhomogeneitites, the RCF life decreased remarkably compared with the homogeneous half-space and showed discreteness.

This paper implements the prediction of the RCF life of inhomogeneous materials under EHL condition.

This paper aims to clarify the effects of metallic nanoparticles (NPs) additives and room temperature ionic liquids (ILs) on the tribological performance of electric contacts.

Tribological properties of copper (Cu) and silver (Ag) NPs as lubricant additives in different lubricants of ILs or polyalphaolefin (PAO) oils under applied electric currents were investigated. After tribological tests, morphologies of worn surfaces were observed; meanwhile, lubrication and anti-wear properties were analyzed.

The mixture solution of the IL and Cu NPs showed desirable lubrication and anti-wear properties due to the reduction of electrocorrosion and the enhancement of rolling effects of particles in the contact region. The anti-wear performance of Cu NPs is better than that of Ag NPs due to the difference in the particle size. The PAO oil with the Cu NPs additives showed poor lubrication properties due to the low solubility of the particles in the oil. When the direction of applied current was changed, the friction of the lubricant with better conductivity was more stable in the variation trend.

This paper begins with a study of tribological properties of Cu and Ag NPs as lubricant additives in different lubricants of IL or PAO oils under applied electric currents. The authors then propose several methods and possible solutions which could be implemented to improve the tribological performance of electric contacts.

To ensure the motion attitude and stable contact force of massage robot working on unknown human tissue environment, this study aims to propose a robotic system for autonomous massage path planning and stable interaction control.

First, back region extraction and acupoint recognition based on deep learning is proposed, which provides a basis for determining the working area and path points of the robot. Second, to realize the standard approach and movement trajectory of the expert massage, 3D reconstruction and path planning of the massage area are performed, and normal vectors are calculated to control the normal orientation of robot-end. Finally, to cope with the soft and hard changes of human tissue state and body movement, an adaptive force tracking control strategy is presented to compensate the uncertainty of environmental position and tissue hardness online.

Improved network model can accomplish the acupoint recognition task with a large accuracy and integrate the point cloud to generate massage trajectories adapted to the shape of the human body. Experimental results show that the adaptive force tracking control can obtain a relatively smooth force, and the error is basically within ± 0.2 N during the online experiment.

This paper incorporates deep learning, 3D reconstruction and impedance control, the robot can understand the shape features of the massage area and adapt its planning massage path to carry out a stable and safe force tracking control during dynamic robot–human contact.

This paper investigates the dynamic pricing strategy of a firm for the successive-generation products under the conditions of the limited trade-in duration and strategic customers. Further, it explores the effect of a limited trade-in duration on the choice of the myopic and strategic customers, besides the optimal dynamic pricing and trade-in strategy of the firm.

Based on the choice behavior of the myopic and strategic customers, the authors have developed a two-period game-theoretic analytical model to decide the optimal retail prices of the successive-generation products and the optimal trade-in rebate when the firm adopts a dynamic pricing strategy and then investigate three extensions of the basic model to discuss the change in the results owing to the relaxation of certain conditions.

The authors find from the results that, in terms of profit maximization, it is better to extend the limited trade-in duration, and hence, the firm should implement a dynamic pricing strategy. However, in the situation of using a static pricing strategy, the firm should extend the limited trade-in duration only if the incremental value of the new generation products is below a certain threshold. Moreover, the firm should use a dual rollover strategy instead of a single rollover one. If all customers in the market are myopic, then the firm should also extend the limited trade-in duration.

This study mainly discusses the impact of limited trade-in duration on the firm's dynamic pricing strategy when facing strategic customers, which provides several directions for future research. First, if the government offers subsidies to consumers, how will strategic consumers make purchase decisions? How would the enterprise make its pricing decision? Second, when asymmetric information exists between consumers and firms, how will it affect consumers' choice behavior and firms' pricing decisions? All these issues are worth exploring in the future.

These results offer certain managerial insights for the firm in the decision making on pricing within the trade-in program.

This is the first work to study the dynamic pricing strategy of the firm for the successive-generation products under the conditions of the limited trade-in duration and strategic customers. Further, this work discusses the changes in results owing to the relaxation of certain conditions.

The purpose of this paper is to propose an efficient algorithm for computing the transient responses on wind turbine (WT) towers struck by lightning.

The tower is modeled as an electric network and a set of formulas are given for calculating the related electrical parameters. The parameters of grounding rods are also proposed. Based on the numerical representation of the transient characteristics of inductive elements, the electric network is converted into an equivalent circuit. The transient responses are obtained from the equivalent circuit by using circuit analysis method.

The calculated results are in good agreement with results computed by a hybrid method in frequency and time domain, which demonstrating the validity of the proposed method.

The transient responses on WT towers struck by lightning are computed using the numerical calculation method directly in time domain and electric field, electromagnetic field and induced potentials will be computed from the responses directly, which can provide guidelines for lightning protection design.

Over the past several decades, there has been an increasing trend towards inter-city cooperation, which is an efficient policy option to deal with the challenges from globalization, regionalization and the externalities resulting from urban entrepreneurialism. Specific to China, the city governments, which mainly refer to prefecture-level and county-level governments, have also made many attempts to cooperate with respect to their local economic development and public affairs. Nevertheless, the results of these initiations to cooperate vary to a great extent. Based on a review of regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu. The findings demonstrate that China's idiosyncratic institutional background has a significant impact on the shaping of inter-city cooperation. For the most part, leading small groups (LSGs) and their leadership property tend to determine the effectiveness of inter-city cooperation.

To examine the effect of the LSGs, we categorize them into three types, groups with strong leadership, weak leadership and self-forming leadership. Through reviewing regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu, we try to probe the role of leading groups in the settlement of cross-administrative border issues.

Based on these three cases, the conclusion can be drawn that the leadership type of the LSG can exert an important influence on the efficiency of inter-city cooperation. If there is a leader with a higher administrative rank or authority, the cooperation can be quite efficient. Otherwise, the cooperative ending might be very negative. In terms of the operation principle, we can infer that even though the cities are always self-development oriented, the leader with higher authority or a strong coordinating capacity can convince and persuade the city leaders to overcome their self-centered behavior template and boost the cooperation to March on smoothly. Also, it means that the LSG is constrained by its personalistic characteristic. Key command derives from the person who chairs the LSG other than specific rules and norms. If the lead of the LSG leaves his position, the cooperation might just become paralyzed. From this point of view, the lack of legal basis remains to be the LSGs' significant deficiency and the future reform should attach more importance to the legalization of the LSGs so the operation of LSGs can be more standard and stable.

Many scholars have proposed their own theoretical models to explain the reason some cities successfully and effectively form cooperative relations, while the other cities do not. However, their models do not consider the idiosyncratic context of China or, how and to which extent LSGs can promote cooperation. Therefore, this paper seeks to probe which path in the context of China cities usually follows in the formation of joint efforts, and what role LSGs play in enabling cities to cooperate.

This study aims to explore how the concept of extended self-influences luxury shopping tourism consumption among Chinese tourists. It explores why luxury shopping is important for Chinese tourists. Specifically, this study focuses on a strategically important emerging market segment: post-1990s female Chinese tourists.

To explore the link between the extended self and luxury shopping tourism consumption among post-1990s Chinese female tourists, this study adopted a qualitative and interpretive approach. A total of 22 semi-structured in-depth interviews were carried out to collect the data.

This qualitative inquiry found that luxury shopping during overseas holidays has some subtle differences from luxury shopping in China, as the conceptualisation of luxury is highly context-based. Through a focus on gender and generational differences, the current study reveals that the idea of individuality has started to influence their luxury purchases.

The study shows how different selves are associated with luxury shopping. It thus provides empirical evidence regarding the reasons behind their motivation, especially for shopping overseas to get a good price and an exclusive and enjoyable luxury shopping experience abroad. Also, it was found that curiosity about buying luxury products is viewed as less favoured and logical shopping will be a future trend. Individuality is becoming a trend for younger consumers.

Theoretically, by linking the “extended self” with luxury shopping tourism, this study provides the social-psychological aspects of luxury shopping tourism. Instead of focusing on particular destinations, this study provides compressed but also focused inquiries to explore how the concept of the self-influences post-1990s female Chinese tourists’ shopping consumption while on holiday, and how this luxury shopping experience influences their concept of the self.

本文运用“延伸自我”概念对中国泳客在境外购买奢侈品的行为和意义进行探讨, 从而进一步了解中国游客对奢侈品的消费形态。 研究主要专注在中国90后女性市场, 女性市场已被许多学者以即市场营销人员认定为新兴市场领域。

通过22个深度访谈的所得数据表明境外奢侈品高买行为与自我概念有着紧密的联系, 并为消费者购买动机背后的原因提供了实证

在境外旅游过程中购买奢侈品有非常大的价格优势, 同时又能为消费者提供独特的购物体验, 中国90后女性的奢侈品购买行为日趋理性并在出行之前做好详细的购物计划, 个性的展示将成为中国年轻女性奢侈品消费的主导因素。

该研究的理论贡献是探索自我概念如何影响90年代后中国女性游客在境外旅行度假时的奢侈品购物行为, 以及这种奢侈品购物体验如何影响其自我概念。

关键词 购物，中国游客，女性， 延伸自我，自我概念

文章类型 研究论文

El estudio se dedica a explorar cómo influir el conceptöauto-extensión¨ al comportamiento de comprar los artículos de lujo en el extranjero entre los chinos turísticos, también a explorar la importancia de tal caso para ellos.

Este estudio ha adaptado un enfoque cualitativo entre 22 entrevistas en profundidad semiestructuradas para la recopilación de datos y muestra cómo se asocian diferentes seres con las compras de lujo.

Por lo tanto, se proporciona las pruebas evidentemente sobre las razones detrás de su motivación. Comprar artículos de lujo durante los viajes al extranjero tiene una gran ventaja de precio, al tiempo que las ofrece una experiencia especial. Estos actos se están volviendo más racionales y tienen planes de compras detallados antes de viajar. La exhibición de la personalidad se convertirá en el factor dominante en cuanto al consumo de artículos de lujo por parte de tales chinas.

Principalmente se enfoca a un nuevo campo del mercado en lo cual los consumidores son las chicas quienes nacieron después del año 1990.

The purpose of this paper is to numerically investigate the effect of guide vane unsteady passing wake on the rotor blade tip aerothermal performance with different tip clearances.

The geometry and flow conditions of the first stage of GE-E3 high-pressure turbine have been used to obtain the blade tip three-dimensional heat transfer characteristics. The first stage of GE-E3 high-pressure turbine has 46 guide vanes and 76 rotor blades, and the ratio of the vane to the blade is simplified to 38:76 to compromise the computational resources and accuracy. Namely, each computational domain comprises of one guide vane passage and two rotor blade passages. The investigations are conducted at three different tip gaps of 1.0, 1.5 and 2.0 per cent of the average blade span.

The results show that the overall discrepancy of the heat transfer coefficient between steady results and unsteady time-averaged results is quite small, but the dramatic growth of the instantaneous heat transfer coefficient along the pressure side is in excess of 20 per cent. The change of the aerothermal performance is mainly driven by turbulence-level fluctuations of the unsteady flow field within gap regions. In addition, the gap size expansion has a marginal impact on the variation ratio of tip unsteady aerothermal performances, even though it has a huge influence on the leakage flow state within the tip region.

This paper emphasizes the change ratio of unsteady instantaneous heat transfer characteristics and detailed the mechanism of blade tip unsteady heat transfer coefficient fluctuations, which provide some guidance for the future blade tip design and optimization.

Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time by adjusting the ratio of mixed powders via a dual-feed system. Here, the authors provide a systematic report on the effects of the Nb content on the microstructure, Laves phase segregation and mechanical properties of as-received LMD nickel-based alloys. The effects of the Nb content on the microstructure, precipitation evolution and mechanical properties of the subsequent heat-treated LMD samples are also discussed in this paper.

Thus, the present research aims to obtain a better understanding of the effect of Nb content on the microstructural and mechanical properties of the as-received LMD Inconel 718 alloys through high-throughput sample fabrication. The microstructures were characterized by scanning electron microscopy and energy-dispersive spectroscopy, electron back-scattered diffraction and transmission electron microscopy methods. The mechanical properties were obtained from compressive tests and nano-indentation tests. Electrochemical tests, including electrochemical impedance spectroscopy and potentiodynamic polarizations, were carried out to evaluate the durability of the Inconel 718 alloys. Results can provide a factual basis for future applications of the functionally graded by AM technology.

The grain size of the as-received LMD Inconel 718 alloys decreased with the Nb content. The Laves phase distribution at the macro level was relatively uniform and the Laves phase exhibited a 1.5-fold nano-hardness compared with the matrix. The strength improvement for the as-received LMD Inconel 718 alloys with Nb content was attributed to grain refinement and enhancement of the Laves phase in terms of both hardness and content. Meanwhile, the corrosion resistance increased with the increase of the Nb content, especially for the pitting potential, which was attributed to the optimization of carbide precipitates due to the strong affinity between niobium and carbon.

The results provide a factual basis for the Nb content effect in LMD nickel-based alloys, and this method can greatly promote the development of new materials. The authors believe that this study makes a significant contribution to the literature and is suitable for publication.

The problem of urban drainage has become more serious with the rapid development of urban construction. The idea of combining geographic information system (GIS) technology with flood control in solving the urban drainage problem has received increasing attention. The idea and process of GIS as the key technology in vertical planning were analyzed in this study based on the GIS technology characteristics. This paper presents the new idea of integrating flood control and drainage mode into vertical planning and the optimization method in vertical planning. Taking the vertical planning of the north shore of Xiaoqing River in Ji'nan as an example, the model of the present scenario and the corresponding terrain model of the different flood control drainage standards were established. The standard model of the flood control and drainage of Xiaoqing River was determined through comparison. The relationship between vertical planning, flood control, and drainage mode was analyzed and optimized on the basis of the practical engineering results. Improving the optimization measures can result in the good convergence of vertical planning and drainage content, which is conducive to the development of urban flood control.