Estimating the robustness of questionnaire results: lessons from a mixed-mode survey of expectations for tele-working and road-based business travel

The robustness of questionnaire results to various forms of bias are explored in the context of a dual-mode (web and hardcopy) survey of employers’ anticipations of levels of employee commuting and business travel activity under a range of future ICT scenarios. The questionnaire incorporated several innovative features which, together with the dual-mode format, allowed an unusually wide range of analyses. For example: the robustness of respondents’ opinions was tested by examining the effect of incorporating alternative versions of a briefing text, one being very positive and one very negative, about the role of ICT; instrument bias was identified via detailed comparison of the results from the two versions of the questionnaire; and the impact of exogenous factors which are often ignored or taken as constant was assessed via special supplementary questions. Analysis showed that the robustness of opinions and expectations varied and was influenced by respondent characteristics, and that results from the two versions of the questionnaire differed significantly. It is concluded that opinions and expectations are less robust, and questionnaire results are more subject to bias and myopic interpretation, than is generally recognised and that web-based surveys seem particularly vulnerable to sampling bias. Methods are suggested for measuring robustness, for reducing bias and for validating and contextualising results. The use of contrasting briefing texts is recommended as a means of establishing the robustness of opinions and expectations while supplementary questions are recommended for validating and contextualising SP and SE exercises.

NFM盾构机带压开舱换刀技术

文章以深圳地铁2号线东延线2222标段工程中采用的带压开舱换刀试行方法为依托,针对NFM土压平衡盾构机的设备情况,总结出了相关的技术方案,主要包括开舱前的准备工作和带压开舱换刀作业的整个实施流程及相关技术要点。     

隧道内爆炸作用衬砌结构的动力响应和损伤机理研究

隧道内爆炸作用可能导致其衬砌结构的破坏和坍塌,造成车辆通行受阻和生命财产损失。为了研究隧道衬砌结构的抗爆性能,应用AUTODYN软件建立了隧道衬砌-岩石-土壤的三维数值模型,并考虑炸药-空气-结构的流固耦合相互作用,以及隧道内爆炸作用对衬砌结构的动力响应和损伤机理进行了数值模拟分析。结果表明:在不同炸药量作用下,超压峰值及冲量以爆心地面投影点为中心,向四周迅速衰减,表现出一定的规律性;离爆心最近的底板首先出现损伤,并向四周扩展,直墙角部由于受到底板竖向变形而引起的拉应力作用,较早地出现损伤,在直墙壁和拱顶产生纵向和环向的裂缝,这些裂缝把整体式隧道衬砌结构分割成大小不等的混凝土块体。     

Measuring quality of service in dial-a-ride operations: the case of a Canadian city

In many countries, dial-a-ride services are provided by public authorities to elderly and handicapped people who cannot use regular transit. Cost minimization is key to running these services, but one can observe a growing interest in quality measurement and improvement. A first step in improving quality is to define a quality measurement scale specific to dial-a-ride services. A second step is to incorporate quality measurements in mathematical models that serve as a basis for optimization algorithms. To this end, an extensive survey of dial-a-ride users was conducted in Longueuil, the largest suburb of Montreal, Canada. This paper describes the steps of the survey and presents its main conclusions: (1) 56 attributes were identified based on interviews, (2) the questionnaire developed has proved to be reliable and valid, (3) an exploratory factor analysis allowed us to determine 13 dimensions of quality in dial-a-ride services, (4) the most important criteria for users were identified, and (5) population segmenting variables by which subgroups of users can be categorized were also determined. Managerial implications of our results are also discussed.     

Bridge officers’ non-technical skills: a literature review

The present review examines the research literature on Non-Technical Skills (NTS) used by ships’ bridge officers in connection with navigation. The aim of the study was to (i) identify the cognitive and interpersonal skills which have been the focus of previous studies and (ii) explore how the content of these skills has been described. Databases searched included Academic Search Premier, PsycINFO, Science Direct, and Web of Science. Nineteen studies were included in the review. Five NTS were identified: situation awareness (SA), decision-making (DM), workload management (WM), communication, and leadership. In addition to discussing each skill, the review raises four overarching issues with the present literature for the bridge domain: (1) Have all the relevant skills been subject to exploration? (2) Have the skills identified been explored in detail? (3) There seems to be an uneven distribution of research between cognitive and interpersonal skills. (4) There is little research into understanding the skills as a complete taxonomy. Knowledge on how the skills are linked and interplay with one another is incomplete. Overall, further research on all these aspects of NTS in the maritime domain could increase scientific understanding and contribute to bridge operational practice and to the further development and evaluation of NTS training such as Bridge Resource Management (BRM).     

Employability skills of maritime business graduates: industry perspectives

The maritime industry underpins international business and world trade. As to be expected, business management is critical for the maritime industry, requiring highly trained individuals and teams to lead the development, implementation and control of sound contemporary management practices. Maritime business degrees are developed by universities to meet such demand by providing graduates with sufficient skills for the onshore business-related roles. This empirical study conducted in Australia, USA and Canada, investigates current and future industry employability skills for maritime business graduates through focus groups, individual interviews and an online survey with senior managers in maritime organisations. This study found the important employability skills for maritime business graduates which include communication, problem solving, adaptability, self-management, team work, and digital literacy and technology. Demand for digital literacy and technology knowledge and skills have increased due to the maritime industry having a trend of moving towards digitalisation and automation. However, the survey findings revealed that a skills focus for maritime business graduates will not be the technology itself but the use and management of technology. In relation to future skills/knowledge required from maritime business degree graduates in 10 years’ time, communication and adaptability are recognised as being the most important. Employers expect that maritime business graduates should be able to adopt new technology and be competent in communication, and be more adaptable given the highly dynamic nature of the maritime industry. Moreover, they require graduates to be equipped with a higher level of computer skills, have a strong work ethic and multilingual skills.     

Spectral Wave Modeling in Very Shallow Water at Southern Coast of Caspian Sea

This study evaluates the capability of the Simulating WAves Nearshore (SWAN) wave model (version 41.01) in predicting significant wave height and spectral peak energy content for swell waves in very shallow water of surf zone during depth-induced wave breaking and dissipation. The model results were compared with field measurements at five nearshore stations. The results demonstrated that some breaker index formulations were successful for significant wave height prediction in surf zones. However, an incorrect shape of the energy spectrum and overestimated near spectral peak energy content at shallow water stations were obtained using all of the embedded depth-induced wave breaking formulations in SWAN. The dependent breaker index on relative depth (K_pd) formulation, which was successful in predicting near spectral peak energy content, resulted in an average error of 30%. Finally, this formulation was modified to enhance the model performance in reproducing the spectral peak energy content.     

CFD Analysis of Ship-to-Ship Hydrodynamic Interaction

A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code, and the results are compared with experimental data and with the results of a panel method analysis. Two ship models have been used in the interaction forces analysis: a tug and a tanker, advancing parallel to each other with different lateral distances and two different values of the fluid depth. Computations are carried out with four different flow models: inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface. A fair agreement was obtained with available experimental data and results obtained by panel method. The influence of viscosity in the computations is found to be comparatively weak, while the wavemaking effects may be important, at small magnitude of the horizontal clearance.