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Contains a report on three‐dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels. Multisurface elasto‐viscoplastic material models are employed for consideration of the mechanical behaviour of the soil and the shotcrete shell supporting the excavation. Both are formulated within the framework of closest point projection algorithms. For soil a cap model is used, consisting of a curved failure surface, a tension cut‐off and an elliptical cap. The latter allows consideration of the evolution of plastic strains even for the limiting case of a purely volumetric stress state. The movement of the cap is governed by a hardening law, describing the relation between the hydrostatic pressure and void ratio. The shotcrete model is a rotating crack model, taking ageing of the maturing concrete into account. It consists of a strain‐hardening Drucker‐Prager cone and three Rankine (crack) surfaces. Demonstrates the usefulness of the cap model to predict the mechanical behaviour of the soil by means of tests on remoulded, saturated clay. The model parameters of the clayey silt of Vienna, where the analysed tunnel is located, are fit to standard test results. The parameters of the shotcrete model are fit to test results published in the literature. Compares the analysis of a single‐track tunnel with the results of field measurements from sliding micrometers. Furthermore, the stresses in the shotcrete lining are examined. In view of the inhomogeneity of the material and of unavoidable deficiencies of the measurements it is fair to say that the mechanical effects resulting from the excavation of tunnels are modelled reasonably well.

Transfer relations represent analytical solutions of the linear theory of circular arches, relating each one of the kinematic and static variables at an arbitrary cross-section to the kinematic and static variables at the initial cross-section. The purpose of this paper is to demonstrate the significance of the transfer relations for structural analysis by means of three examples taken from civil engineering.

The first example refers to an arch bridge, the second one to the vault of a metro station and the third one to a real-scale test of a segmental tunnel ring.

The main conclusions drawn from these three examples are as follows: increasing the number of hangers/columns of the investigated arch bridge entails a reduction of the maximum bending moment of the arch, allowing it to approach, as much as possible, the desired thrust-line behavior; compared to the conventional in situ cast method, a combined precast and in situ cast method results in a decrease of the maximum bending moment of an element of the vault of the studied underground station by 46%; and the local behavior of the joints governs both the structural convergences and the bearing capacity of the tested segmental tunnel ring.

The three examples underline that the transfer relations significantly facilitate computer-aided engineering of circular arch structures, including arch bridges, vaults of metro stations and segmental tunnel rings.

Research abounds highlighting the differences between males and females when they travel. Even in business travel, these differences have been acknowledged, with suppliers and marketers spending significant money to develop and market products to accommodate them. The purpose of this study is to ascertain whether differences exist in terms of mobile application usage between male and female business travellers.

A mixed method approach is followed. An internet-based survey is distributed and in-depth interviews conducted with South African business travellers. The Mann–Whitney U-test is used to test the differences between males and females and their mobile application usage. Content analysis is used to analyse the interviews.

The results show that mobile applications are perceived as more important by females than males in all the phases of the travel cycle, although most of these differences in perceived importance were not significant.

Owing to the online data-collection method and the self-selective process, the findings cannot be generalised to the global population of business travellers who use mobile applications.

The results should caution corporate organisations, travel management companies and their application developers not to spend unnecessary technological and financial resources on developing applications to accommodate differences between males and females, which might not exist. Companies should rather spend money on developing applications that will enhance and add convenience to the business traveller’s experience.

The main contribution of this study lies in investigating the applications market, particularly in the context of business travel. Applications focussed on specific sectors of the tourism industry, such as business travel applications, serve business travellers differently from generic travel applications. This research examines business travel-specific applications and expands the scale and scope of the enquiry, concentrating on the travellers’ view.

本论文主要研究男人和女人在旅游中的行为区别。特别是在商务旅游中, 男女差别确实存在, 这也验证了供应商和营销商在开发营销产品中的针对性和区别性。本论文旨在验证是否男女商务旅游者对使用移动APP存在区别。

本论文采用混合采样方法。采样方式通过网络问卷和深度访谈, 采样群体为南非商务游客。本论文采取Mann–Whitney U检验来测试男女在移动APP使用上的区别。本论文还采取文本分析法来分析访问数据。

研究结果表明女性游客在各个旅游阶段都比男性游客对移动APP更看重, 而这些区别在统计计算上并没有获得显著效果。

由于线上采样和自助问卷的采样限制, 研究结果不能推广到全球商务旅客对于使用移动APP的态度。

研究结果可以警示企业机构、旅游管理公司、以及APP开发商不要花费不必要的科技和财力资源来迎合男女受众的需求。因为这个区别可能不存在。公司应该花费财力在开发APP上, 使得商旅客人的使用体验更加便捷。

本论文最重要的贡献就是研究了商旅APP市场。商旅APP区分于普通旅游APP。我们的研究检验了商旅客人APP以及扩展其度量和研究视野到旅游者的角度。

移动设备， 性别， 商务旅行， 商务旅行周期， 商务旅客， 移动商务旅行应用

This paper describes a small research project undertaken in a technical college in Qatar on the use of iPads in the classroom. iPads were trialed for a semester each in mathematics and physics classes; students completed pre- and post-surveys. Classroom observations were carried out and interviews were conducted with both faculty (N=3) and students (N=19). Over 80% of students reported positively on the iPad as being “helpful” to “very helpful” for learning new things and course materials, for increasing their interaction with online course materials and getting course information and for exploring additional material related to course topics. Faculty perceptions of iPad use in class were also positive.

The purpose of this paper is to present a new bond slip model for reinforced concrete structures. It consists in an interface element (3D) which represents the interface between concrete (modeled in 3D) and steel, modeled using 1D truss elements.

The formulation of the interface element is presented and verified through a comparison with an analytical solution on an academic case. Finally, the model is compared with experimental results on a reinforced concrete tie.

Contrary to the classical perfect or “no-slip” relation which supposes the same displacement between steel and concrete, the proposed model is able to reproduce both global (force-displacement curve) and local (crack openings) results.

The proposed approach, applicable to large-scale computations, represents a valuable alternative to the no-slip relation hypothesis to correctly capture the crack properties of reinforced concrete structures.

This paper aims to develop a new multi-fiber element for predicting the structural behavior of planar-reinforced concrete (RC) members.

In this work, an exact multi-directional stiffness matrix is analytically derived based on the post-cracking bond-slip interaction between concrete and steel bars. The approach is also extended for large displacement analysis using Green–Lagrange finite strain tensor. In the proposed formulation, the weak form of governed differential equations is approximated by a trial-function expansion based on a finite strain-description and an additional degree of freedom for steel bars.

The findings provide a realistic description of cracking in the concrete structure. Numerical studies are conducted to examine the accuracy of the suggested approach and its capability to predict fairly complex responses of RC models. The findings prove that the proposed element can evaluate local and global responses of RC members, and it can be used as a reliable tool to reflect bond-slip effects in large displacement level. This leads to a robust and precise model for non-linear analysis of RC structures.

The methodology is capable of simulating coupled inelastic shear-flexural behavior of RC members through local stress field theory and Timoshenko beam model.

The cracking of a reinforced concrete lining has a significant influence on the safety and leakage of pressure tunnels. This study aims to develop, validate and apply a numerical algorithm to simulate the lining cracking process during the water-filling period of pressure tunnels.

Cracks are preset in all lining elements, and the Mohr−Coulomb criterion with a tension cutoff is used in determining whether a preset crack becomes a real crack. The effects of several important factors such as the water pressure on crack surfaces (WPCS) and the heterogeneity of the lining tensile strength are also considered simultaneously.

The crack number and width increase gradually with the increase in internal water pressure. However, when the pressure reaches a threshold value, the increase in crack width becomes ambiguous. After the lining cracks, the lining displacement distribution is discontinuous and steel bar stress is not uniform. The measured stress of the steel bar is greatly determined by the position of the stress gauge. The WPCS has a significant influence on the lining cracking mechanism and should not be neglected.

A reliable algorithm for simulating the lining cracking process is presented by which the crack number and width can be determined directly. The numerical results provide an insight into the development law of lining cracks and show that the WPCS significantly affects the cracking mechanism.

The popularity of mobile technologies and applications is constantly growing and undoubtedly changing consumers’ and providers’ behavior. The purpose of this study is to provide a comprehensive systematic literature review of academic research related to mobile technologies and applications in smart tourism published between 2012 and June 2017.

Published peer-reviewed articles were gathered from the three largest and most popular online databases and search engines – EBSCO host, Science Direct and Google Scholar and ENTER conference proceedings. Based on a keyword-driven search and content analysis, 126 articles were determined to be relevant to this study.

Selected publications were analyzed in accordance with the proposed research questions and thematically classified into three main categories: consumer perspective, technological perspective and provider perspective. The findings contribute to a better overall understanding of recent research into mobile technologies and applications in smart tourism by presenting the main results, methods, trends and other insights of relevant publications.

Although the researchers used two databases, one search engine and ENTER conference proceedings to collect articles, there is the possibility that some studies connected to the topic were not included. The study did not include books, other conference proceedings, literature reviews, theses, business reports and other possibly relevant publications.

This study provides a systematic review of the most recent published academic research (2012-June 2017; also including “Online First” articles) on mobile technologies and applications in smart tourism. The results of this study provide an agenda for future research in tourism and hospitality industry by identifying major trends and developments in smart tourism.

To provide an insight in one relatively simple and efficient numerical model for analysing reinforced and prestressed concrete structures, and to raise a discussion leading to the creation of one universal and robust 3D algorithm.

A new numerical model for analysing reinforced and prestressed concrete structures is developed and main theoretical details are described to aid the understandings. The approach is clear, easily readable and the body of the text is divided into logical sections starting from theoretical explanations ending in the large number of different practical examples.

Provides information about developing new and relatively simple numerical model for analysing reinforced and prestressed concrete structures, indicating what can be improved. Recognises the lack of knowing real behaviour of 3D concrete and starts a discussion on it.

The knowledge of the 2D and especially 3D concrete behaviour is still poor and the concrete model developers use many simplifications. So, many new experiments should be performed and better numerical models should be developed. There is large area for researchers but having in mind that experiments are very expensive.

Obtained results of the 3D analysis of reinforced and prestressed concrete structures can stand as a benchmark for future researches in this field especially to the young researchers and concrete model developers.

This paper presents new and very simple numerical model for analysing reinforced and prestressed concrete structures. Paper could be very valuable to the researchers in this field as a benchmark for their analyses.

Regeneratively cooled thrust chamber is a key component of reusable liquid rocket engines. Subjected to cyclic thermal-mechanical loadings, its failure can seriously affect the service life of engines. QCr0.8 copper alloy is widely used in thrust chamber walls due to its excellent thermal conductivity, and its mechanical and fatigue properties are essential for the evaluation of thrust chamber life. This paper contributes to the understanding of the damage mechanism and material selection of regeneratively cooled thrust chambers for reusable liquid rocket engines.

In this paper, tensile and low-cycle fatigue (LCF) tests were conducted for QCr0.8 alloy, and a Chaboche combined hardening model was established to describe the elastic-plastic behavior of QCr0.8 at different temperatures and strain levels. In addition, an LCF life prediction model was established based on the Manson–Coffin formula. The reliability and accuracy of models were then verified by simulations in ABAQUS. Finally, the service life was evaluated for a regenerative cooling thrust chamber, under the condition of cyclic startup and shutdown.

In this paper, a Chaboche combined hardening model was established to describe the elastoplastic behavior of QCr0.8 alloy at different temperatures and strain levels through LCF experiments. The parameters of the fitted Chaboche model were simulated in ABAQUS, and the simulation results were compared with the experimental results. The results show that the model has high reliability and accuracy in characterizing the viscoplastic behavior of QCr0.8 alloy.

(1)The parameters of a Chaboche combined hardening constitutive model and LCF life equation were optimized by tensile and strain-controlled fatigue tests of QCr0.8 copper alloy. (2) Based on the Manson–Coffin formula, the reliability and accuracy of constitutive model were then verified by simulations in ABAQUS. (3)Thermal-mechanical analysis was carried out for regeneratively cooled thrust chamber wall of a reusable liquid rocket engine, and the service life considering LCF, creep and ratcheting damage was analyzed.