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This paper aims to study the influence of thermal effect on the performance for a high-speed conical hybrid bearing including stability and minimum oil film thickness.

A thermal hydrodynamic (THD) model and dynamic model of single mass rigid rotor system were established by taking conical hybrid bearing with shallow and deep pockets as the research object, dynamic coefficient and stability parameters of bearing-rotor system were obtained by using finite element method (FEM) and finite difference method (FDM) to solve computational models of Reynolds equation, energy equation and viscosity-temperature equation. Minimum oil film thickness was obtained based on bearing force balance. Dynamic coefficient was compared with previous findings.

After considering thermal effect, the dimensionless critical mass decreases, a significant decrease in the instability speed, and the stability of the system decreases greatly; the minimum oil film thickness decreases because of thermal effect.

The thermal effect is combined with dynamic characteristics to analyze stability of the rotor system for a conical hybrid bearing. Influence of thermal effect on minimum oil film thickness is studied.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0542/

The purpose of this paper is to study the influence of lubricant temperature-viscosity on the performance for a hydrodynamic journal floating ring bearing (FRB), including ring-journal speed ratio and stability.

The finite difference method was used to solve computational models of Reynolds equation, energy equation and temperature–viscosity equation. Dynamic coefficients were obtained based on the floating ring balance. The dynamic model of journal and floating ring was established to deduce the stability criterion of single mass symmetrical rigid FRB rotor system by the Routh–Hurwitz method. The outlet temperature and ring-journal speed ratio under different journal speeds were compared to experimental data.

The temperature–viscosity effect reduces the ring-journal speed ratio and stability of rotor system. According to theoretical and experimental results, the outlet temperature rises and ring-journal ratio drops when the journal speed rises.

The temperature–viscosity effect is combined with dynamic characteristics to analyze the stability of the rotor system and lubrication mechanism for an FRB. Influence of temperature–viscosity on the ring-journal ratio and multi-stable regions of system are studied.

This study aims to investigate users’ adoption of bike sharing systems in China.

This research combined perceived risk factors with existing technology diffusion theories (e.g. technology acceptance model and unified theory of acceptance and use of technology) to develop a research model to examine users’ adoption of bike sharing systems in China. As a result, a research model with 11 hypotheses was developed. The developed research model was empirically tested using data collected from a survey of 298 users in China. Structural equation modeling was used to analyze the collected data.

The findings indicated that perceived usefulness, facilitating conditions and perceived risks were important determinants to the adoption of bike sharing systems. However, perceived ease of use and social influence did not have significant positive impacts on users’ behavioral intention to use bike sharing systems.

It is important for service providers to dedicate their time and efforts in maintaining and repairing bikes to ensure that the bikes are in a good condition to be used. System providers need to work on good solutions to better protect users’ personal information and location information.

This study is first of its kinds in investigating the adoption of bike sharing systems by combining technology diffusion theories and perceived risk theory in China.

本论文旨在研究用户在中国使用共享单车系统的情况。

本论文结合感知风险因素和多个技术扩散理论（比如TAM, UTAUT）来开发一个研究模型, 以研究用户在中国使用共享单车系统的情况。因此, 本论文用十一条假设搭建了一个研究模型。这个研究模型使用问卷采样方式, 收取298份中国用户问卷, 来进行测量。样本通过结构方程模型来进行分析测量。

研究结果表明, 感知实用性、辅助条件、感知风险等是重要因素, 决定着共享单车系统的使用。然而, 方便使用和社会影响等因素对用户使用共享单车系统的意向并没有显著积极影响。

研究型论文

服务提供者投入时间和精力来维护维修单车是非常重要的, 这样能保证单车保持在良好的状态以备用户使用。系统供应商需要找到好的解决方式, 来更好地保护个人信息和地点信息。

本论文是首个类似论文, 结合技术扩散理论和感知风险理论, 在中国研究共享单车系统的使用情况。

UTAUT, TAM, 感知风险, 共享单车系统,使用

Smart city services are supported by information and communication technologies (ICT) referred to as digital technologies which increasingly promise huge opportunities for growth but are faced with system alignment and data integration issues when providing digital services. Therefore, this study aims to use enterprise architecture (EA) in digital transformation of cities by developing an architecture to address system alignment and data integration in digital transformation of cities.

Qualitative method is applied to evaluate the presented architecture based on electric-mobility (e-mobility) scenario, and data was collected using case study via interviews from a municipality in Norway to validate the applicability of EA for digital transformation of city services.

Findings from the interviews were represented in ArchiMate language to model the digital transformation of e-mobility in smart cities. Findings suggest that the architecture serves as a guide to recommend urban administrators of the potential of EA and digital transformation in addressing system alignment and data integration issues in smart cities.

Data used in this study is from a single case, hence there is a need to evaluate the application of EA for digital transformation of city services with data collected from multi-cases.

This study adopts enterprise architecture approach to support city transformation as it has been widely applied by institutions to align business and ICT components.

This study provides implication on how municipalities can use EA and digital transformations towards a sustainable smart city.

An architecture is presented that can be used as a guide to help urban developers and designers in deploying sustainable transport policies for smart cities. Additionally, EA is used to foster digitalization towards achieving system alignment and data integration in cities to support urban environment as they digitally transform services provided to citizens.

This paper aims to develop a theoretical method to analyze the rotation accuracy of rotating machinery with multi-support structures. The method effectively considers the geometric errors and assembly deformation of parts.

A method composed of matrix and FEA methods is proposed to do the analysis. The deviation propagation analysis results and external loads are set as boundary conditions of the model which is built with Timoshenko beam elements to calculate the spatial pose of the rotor. The calculation is performed repeatedly as the rotation angle increased to get the rotation trajectories of concerned nodes, and further evaluation is done to get the rotation accuracy. Additionally, to get more reliable results, the bearing motion errors and stiffness are analyzed by a static model considering manufacturing errors of parts.

The feasibility of the proposed method is verified through a case study of a high-precision spindle. The method reasonably predicts the rotation accuracy of the spindle.

For rotating machinery with multi-support structures, the paper proposes a modeling method to predict the rotation accuracy, simultaneously considering geometric errors and assembly deformation of parts. This would improve the accuracy of tolerance analysis.

Outsourcing of business-logistics services is a well-established business practice that allows an outsourcer to obtain the services or products from a logistics-service provider (LSP). The outsourcer can order a range of logistics services, including but not limited to warehousing, transportation, and forwarding. The outsourcers had traditionally focused on service-provider selection criteria such as costs, quality, and responsiveness while having devoted considerably less attention to how sustainably the practices are carried out. Past research identified different external and internal motivators that facilitate consideration of sustainability in selection of the service providers, whereas the current study investigates the outsourcers’ perception of importance of environmental sustainability in adoption of green logistics practices and selection of LSPs. We use a vantage point of outsourcers (“buyers”) to conduct the quantitative research based on a survey conducted on large manufacturing companies. The findings reveal a (mis)match between the perception of importance and realized inclusion of environmental-sustainability criteria. Ultimately, this study finds a link between the levels of perception and rate of adoption, and provides recommendations for the future adoption of environmental-sustainability criteria in the selection of the LSPs.

In this paper, a first‐order approximation coupling (FOAC) model is investigated to analyze the dynamics of the hub‐beam system, which is based on the Hamilton theory and the finite element discretization method. The FOAC model for the hub‐beam system considers the second‐order coupling quantity of the axial displacement caused by the transverse displacement of the beam. The dynamic characteristics of the system are studied through numerical simulations under twos cases: the rotary inertia of the hub is much larger than, and is close to, that of the flexible beam. Simulation and comparison studies using both the traditional zeroth‐order approximation coupling (ZOAC) model and the FOAC model shows that when large motion of the system is unknown, possible failure exists by using the ZOAC model, whereas the FOAC model is valid. When the rotary inertia of the hub is much larger than that of the beam, the result using the ZOAC model is similar to that using the FOAC model. But when the rotary inertia of the hub is close to that of the beam, the ZOAC model may lead to a large error, while the FOAC model can still accurately describe the dynamic hub‐beam system.

The introduction of Building Information Model (BIM) tools over the last 20 years is resulting in radical changes in the architectural, engineering and construction industry. One of these changes concerns the use of virtual prototyping – an advanced technology integrating BIM with realistic graphical simulations. Construction virtual prototyping (CVP) has now been developed and implemented on ten real construction projects in Hong Kong in the past three years. The purpose of this paper is to report on a survey aimed at establishing the effects of adopting this new technology and obtaining recommendations for future development.

A questionnaire survey was conducted in 2007 of 28 key participants involved in four major Hong Kong construction projects – these projects being chosen because the CVP approach is used in more than one stage in each project. In addition, several interviews are conducted with the project manager, planning manager and project engineer of an individual project.

All the respondents and interviewees give a positive response to the CVP approach, with the most useful software functions considered to be those relating to visualisation and communication. The CVP approach is thought to improve the collaboration efficiency of the main contractor and sub‐contractors by approximately 30 percent, and with a concomitant 30 to 50 percent reduction in meeting time. The most important benefits of CPV in the construction planning stage are the improved accuracy of process planning and shorter planning times, while improved fieldwork instruction and reducing rework occur in the construction implementation stage. Although project teams are hesitant to attribute the use of CVP directly to any specific time savings, it is also acknowledged that the workload of project planners is decreased. Suggestions for further development of the approach include incorporation of automatic scheduling and advanced assembly study.

Whilst the research, development and implementation of CVP is relatively new in the construction industry, it is clear from the applications and feedback to date that the approach provides considerable added value to the organisation and management of construction projects.

This paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation and multi-body dynamics and put forward the speed threshold for safe running of train under different crosswind speeds.

The computational fluid dynamics method is adopted to simulate the aerodynamic force in the whole process of train passing each other by using dynamic grid technology. The dynamic model of vehicle-bridge coupling system is established considering the effects of aerodynamic force of train passing each other under crosswind, the dynamic response of train intersection on the bridge under crosswind is computed and the running safety of the train is evaluated.

The aerodynamic force of trains' intersection has little effects on the derailment factor, lateral wheel-rail force and vertical acceleration of train, but it increases the offload factor of train and significantly increases the lateral acceleration of train. The crosswind has a significant effect on increasing the derailment factor, lateral wheel-rail force and offload factor of train. The offload factor of train is the key factor to control the threshold of train speed. The impact of the aerodynamic force of trains' intersection on running safety cannot be ignored. When the extreme values of crosswind wind speed are 15 m·s⁻¹, 20 m·s⁻¹ and 25 m·s⁻¹, respectively, the corresponding speed thresholds for safe running of train are 350 km·h⁻¹, 275 km·h⁻¹ and 200 km·h⁻¹, respectively.

The research can provide a more precise numerical method to study the running safety of high-speed trains under the aerodynamic effect of trains passing each other on bridge in crosswind.