Search results

The mechanical properties between wheel and ground will affect the motion performance of wheeled omnidirectional mobile robot (OMR). MY3 wheel is an omnidirectional wheel. This paper aims to analyze the contact mechanical characteristics between MY3 wheel and ground to improve the motion accuracy of an omnidirectional mobile platform with MY3 wheel (MY3-OMR).

This method takes MY3 wheel as the research objective. The normal and tangential contact mechanics model and rolling contact mechanics model of MY3 wheel are established by analyzing the structure of MY3 wheel, and thereby, the slip ratio of MY3 wheel in the process of motion is calculated. The kinematics model of MY3-OMR is optimized by taking the slip ratio as the optimization parameter that aims to improve motion accuracy of MY3-OMR.

The correctness of the mechanical analysis and the feasibility of the method are verified by the MY3-OMR prototype. Let MY3-OMR move along the set circular trajectory and square trajectory, and the error between the motion trajectory before and after optimization and the standard trajectory is obtained. It illustrates that the error in the square trajectory is reduced by 1.5%, and the circular trajectory error is reduced by 2%; therefore, the method is effective.

A method based on contact mechanics is proposed and verified. Through the establishment of wheel-ground contact mechanics model to optimize MY3-OMR kinematics model, and thereby, the motion accuracy of MY3-OMR is improved, which lays a foundation for MY3-OMR engineering application.

This study aims to evaluate the process of value co-creation within wellness tourism by constructing a structural equation model of customer interactions with the environment, service employees and other customers relating to customer-perceived value and customer engagement.

Questionnaires, including wellness tourists’ customer-environment interaction, customer-service employee interaction, customer-customer interaction, customer-perceived value, customer engagement and demographic background, were developed and distributed at well-known wellness tourism destinations around Guangzhou City, Guangdong Province, China. This study collected 528 valid questionnaires from hot spring resorts, national forest parks, mountain parks and spa wellness facilities located in Guangdong Province, China. Structural equation modeling (SEM) was used to analyze the obtained data.

The results reveal that all three types of interactions, which include the customer-environment interaction (CEI), the customer-service employee interaction (CSI) and the customer-customer interaction (CCI), have positive effects on customer-perceived value (CPV) and that CPV positively affects customer engagement (CE). Based on these findings, recommendations for the management of wellness tourism service enterprises are given.

The causes and effects of CPV in wellness tourism, from the perspective of value co-creation, is a rather unexplored area of study. It contributes not only to knowledge about factors that foster CPV but also to the understanding of connections between CPV and CE.

本研究通过构建顾客与环境、服务员工和其他顾客之间互动对顾客感知价值和顾客契合的结构方程模型, 探究养生旅游中的价值共创过程。

本研究在中国广东省广州市附近知名的养生旅游目的地发放问卷, 问卷内容包括养生旅游者的顾客-环境互动, 顾客-服务员工互动, 顾客-顾客互动, 顾客感知价值, 顾客契合和人口统计学背景。本研究从广东省温泉度假区、国家森林公园、山脉等旅游目的地收集了有效问卷528份, 使用结构方程模型(Structural Equation Modeling, SEM)对所获得的数据进行分析。

本研究数据分析结果显示, 顾客与环境互动、顾客与服务人员互动和顾客与顾客互动三种互动类型均对顾客感知价值有正向影响, 而顾客感知价值正向影响顾客契合。在此基础上, 本文针对养生旅游服务企业提出了管理建议。

本研究从价值共同创造的角度对养生旅游中顾客感知价值的因果关系进行了一项未被探索的研究, 这不仅有助于我们识别并培育影响顾客感知价值的因素, 而且有助于我们理解顾客感知价值与顾客契合之间的联系。

Este estudio evaluó el proceso de la creación conjunta de valor dentro del turismo de bienestar, mediante la construcción de un modelo de ecuación estructural de las interacciones de los clientes con (1) el medio ambiente, (2) los empleados de servicio y (3) otros clientes relacionados con el valor percibido por el cliente y el compromiso del cliente.

Los cuestionarios fueron distribuidos en destinos de turismo de bienestar conocidos cerca de la ciudad de Guangzhou, provincia de Guangdong, China. El contenido del cuestionario incluye: interacción cliente-medio ambiente, interacción cliente-empleado de servicio, interacción cliente-cliente, valor percibido por el clientes, compromiso del clientes y el contexto demográficos. Este estudio recopiló 528 cuestionarios válidos de centros turísticos de aguas termales, parques forestales nacionales, montañas y spas de bienestar localizados en la provincia de Guangdong,China. Se utilizó el modelo de la ecuación estructural (Structural Equation Modeling, SEM) para analizar los datos obtenidos.

Los resultados revelan que los tres tipos de interacciones, que incluyen la interacción cliente-medio ambiente (ICMA), la interacción cliente-empleados de servicio (ICES), y la interacción cliente-cliente (ICC), tienen efectos positivos en el valor percibido por el cliente (VPC), y que el VPC afecta positivamente el compromiso del cliente (CC). Con base en estos resultados, se dan recomendaciones de gestión para las empresas de servicios de turismo de bienestar.

Este es un estudio bastante inexplorado sobre la causa y el efecto del VPC en el turismo de bienestar, desde la perspectiva de la creación conjunta de valor (CCV). Este estudio no solo contribuye al conocimiento sobre los factores que fomentan el VPC, sino también a la comprensión de las conexiones entre el VPC y el CC.

This study aims to investigate the effect of incorporating cobalt (Co) into Sn-58Bi alloy on its phase composition, tensile properties, hardness and thermal aging performances. The fracture morphologies of tensile-tested solders are also investigated to correlate the microstructural changes with tensile properties of the solder alloys. Then, the thermal aging performances of the solder alloys are investigated in terms of their intermetallic compound (IMC) layer morphology and thickness.

The Sn-58Bi and Sn-58Bi-xCo, where x = 1.0, 1.5 and 2.0 Wt.%, were prepared using the flux doping technique. X-ray diffraction (XRD) is used to study the phase composition of the solder alloys, whereas scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to investigate the microstructure, fractography and compositions of the solders. Tensile properties such as ultimate tensile strength (UTS), Young’s modulus and elongation are tested using the tensile test, whereas the microhardness value is gained from the micro-Vickers hardness test. The morphology and thickness of the IMC layer at the solder’s joints are investigated by varying the thermally aging duration up to 56 days at 80°C.

XRD analysis shows the presence of Co₃Sn₂ phase and confirms that Co was successfully incorporated via the flux doping technique. The microstructure of all Sn-58Bi-xCo solders did not differ significantly from Sn-58Bi solders. Sn-58Bi-2.0Co solder exhibited optimum properties among all compositions, with the highest UTS (87.89 ± 2.55 MPa) at 0.01 s⁻¹ strain rate and the lowest IMC layer thickness at the interface after being thermally aged for 56 days (3.84 ± 0.67 µm).

The originality and value of this research lie in its novel exploration of the flux doping technique to introduce minor alloying of Co into Sn-58Bi solder alloys, providing new insights into enhancing the properties and performance of these solders. This new Sn-Bi-Co alloy has the potential to replace lead-containing solder alloy in low-temperature soldering.

The purpose of this paper is to enhance the understanding on the electrodeposition of various lead (Pb)‐free solder alloys, so that new studies can be carried out to solve processing issues.

The paper reviews the available reports on the electrodeposition of tin (Sn)‐based solder systems and identifies the challenges in this area.

Compositional control remains a major challenge in this area, where the achievement of desired composition for binary and ternary alloys is subjected to uncertainties. The use of chelating agents in the bath and optimization of parameters can assist the achievement of near‐desired alloy composition. Acidic plating baths are preferred due to their compatibility with photoresists but oxidation of stannous ions causes poor bath stability. Antioxidants, reducing agents and low oxygen overpotential anodes can suppress the oxidation rate and increase the lifespan of plating baths. Apart from chelating agents and antioxidants, various categories of additives can be added to improve quality of deposits. Surfactants, grain refiners and brighteners are routinely used to obtain smooth, fine‐grained and bright deposits with good thermo‐mechanical properties.

The paper provides information on the key issues in electrodeposition of Pb‐free solder alloys. Possible measures to alleviate the issues are suggested so that the electrodeposition technique can be established for mass production of a wider range of solder alloys.

This paper aims to improve the tribocorrosion properties of 316L, thus WC/Ni60 coated 316L was prepared by thermal spraying technique.

Composition and microstructure of WC/Ni60 coating was investigated, and tribological properties of 316 L and WC/Ni60 coating were studied under dry sliding, deionized water and artificial seawater.

The results showed that WC/Ni60 coating was lamellar structure, and the phase composition consisted of γ-Ni solid solution, carbides and borides. Furthermore, the hardness and corrosion resistance of 316 L in static seawater and wear resistance in dry sliding were improved by WC reinforced nickel-based coating. Furthermore, tribocorrosion results demonstrated that wear resistance of WC/Ni60 coating was also significantly better than 316 L, especially for higher load at artificial seawater. The reason can be attributed to the fact that the passive film of WC/Ni60 coating consisted of tungsten carbide, Ni(OH)2 and FeOOH for WC/Ni60 coating and only FeOOH for 316 L.

According to this study, it can be concluded that WC phases acted as a role in resisting the wear damages. Meanwhile, Ni-based materials performed well in corrosion resistance. Thus, the combined-effect Ni-based alloys and WC phases in WC/Ni60 coating showed better tribocorrosion performance than 316 L.

This paper aims to review recent reports on mechanical properties of Sn-Bi and Sn-Bi-X solders (where X is an additional alloying element), in terms of the tensile properties, hardness and shear strength. Then, the effects of alloying in Sn-Bi solder are compared in terms of the discussed mechanical properties. The fracture morphologies of tensile shear tested solders are also reviewed to correlate the microstructural changes with mechanical properties of Sn-Bi-X solder alloys.

A brief introduction on Sn-Bi solder and reasons to enhance the mechanical properties of Sn-Bi solder. The latest reports on Sn-Bi and Sn-Bi-X solders are combined in the form of tables and figures for each section. The presented data are discussed by comparing the testing method, technical setup, specimen dimension and alloying element weight percentage, which affect the mechanical properties of Sn-Bi solder.

The addition of alloying elements could enhance the tensile properties, hardness and/or shear strength of Sn-Bi solder for low-temperature solder application. Different weight percentage alloying elements affect differently on Sn-Bi solder mechanical properties.

This paper provides a compilation of latest report on tensile properties, hardness, shear strength and deformation of Sn-Bi and Sn-Bi-X solders and the latest trends and in-depth understanding of the effect of alloying elements in Sn-Bi solder mechanical properties.

The purpose of this paper is to propose a multi-feature, multi-metric and multi-loop tightly coupled LiDAR-visual-inertial odometry, M³LVI, for high-accuracy and robust state estimation and mapping.

M³LVI is built atop a factor graph and composed of two subsystems, a LiDAR-inertial system (LIS) and a visual-inertial system (VIS). LIS implements multi-feature extraction on point cloud, and then multi-metric transformation estimation is implemented to realize LiDAR odometry. LiDAR-enhanced images and IMU pre-integration have been used in VIS to realize visual odometry, providing a reliable initial guess for LIS matching module. Location recognition is performed by a dual loop module combined with Bag of Words and LiDAR-Iris to correct accumulated drift. M³LVI also functions properly when one of the subsystems failed, which greatly increases the robustness in degraded environments.

Quantitative experiments were conducted on the KITTI data set and the campus data set to evaluate the M³LVI. The experimental results show the algorithm has higher pose estimation accuracy than existing methods.

The proposed method can greatly improve the positioning and mapping accuracy of AGV, and has an important impact on AGV material distribution, which is one of the most important applications of industrial robots.

M³LVI divides the original point cloud into six types, and uses multi-metric transformation estimation to estimate the state of robot and adopts factor graph optimization model to optimize the state estimation, which improves the accuracy of pose estimation. When one subsystem fails, the other system can complete the positioning work independently, which greatly increases the robustness in degraded environments.

Nuclear power is a stable and reliable energy source that can improve energy structure while reducing carbon emissions, which is of great significance for environmental protection and combating climate change. As a unique industry, it is facing rare development opportunities in China and has broad market prospects. However, the characteristics of technical difficulty, loose organizational structure and uneven regional distribution limit the expansion of the nuclear power industry. This paper aims to a better understanding of the accumulation process for innovation capability from the perspective of network evolution and provides policy guidance for the market development of the nuclear power industry (NPI).

Methodologically, social network analysis is used to explore the co-evolution of multidimensional collaboration networks. First, the development and policy evolution of the NPI is introduced to divide the evolution periods. Then, the authors identify and analyze the core organizations, technologies and regions that promote nuclear power patent collaboration. Furthermore, three levels of collaboration networks based on organizations, technologies and regions are constructed to analyze the coevolution of patent networks in China’s NPI.

The results show that nuclear power enterprises always play the foremost role in the organizational collaboration network (OCN), and the dominance of foreign enterprises is replaced by Chinese state-owned enterprises in the third period. The technology hotspot has shifted from nuclear power plant construction to the control system. The regional collaboration network was initially formed in the coastal areas and gradually moved inland, with Guangdong and Beijing becoming the two cores of the network. The scale of three collaboration networks is still expanding but the speed has slowed down.

In response to the pain points of the NPI, this research focuses on multidimensional collaborative innovation, investigates the dynamic evolution process of collaborative innovation networks in China’s NPI and links policy evolution with network evolution creatively. The ultimate result not only helps nuclear power enterprises integrate innovative resources in complex environments but also promotes industrial upgrading and market development.

This study aims to simulate the flow and heat transfer through an air handling unit to reduce its energy consumption by a novel creative idea of using an air-to-air heat exchanger.

To do this, both first and second laws of thermodynamics energy and exergy balance equations were solved numerically by an appropriate developed computer code.

Using the air-to-air heat exchanger in dry conditions decreases the cooling coil load by 0.9 per cent, whereas the reduction for humid conditions is 27 per cent. Similarly, using air-to-air heat exchanger leads to an increase in the first law of efficiency in dry and humid conditions by 0.9 per cent and 36.8 per cent, respectively.

The second law of efficiency increases by 1.55 per cent and 2.77 per cent in dry and humid conditions, respectively. In other words, the effect of using an air-to-air heat exchanger in humid conditions is more than that in dry conditions.