Introduction to the special issue on maritime security

The terrorist attacks of 11 September 2001 heightened awareness about the vulnerability of all modes of transportation to terrorist attack. The issue of maritime security has therefore become a major concern in the international maritime sector over the past several years. Globalization has led to a strong growth in seaborne trade; however, it simultaneously increases vulnerability to not only terrorism but also international criminal activities that threaten the world's supply chain. For example, in 2008, the rise in piracy activities in the Gulf of Aden brought the issue of maritime security to the forefront of international debate. In addition to the direct impact on ships, crews and cargoes, and on the maritime industry and governments, piracy also threatens global seaborne trade, and has an impact on energy security and the environment [UNCTAD, 2009, Review of Maritime Transport 2009 (New York: United Nations)]. Maritime piracy can pose substantial risks to seaborne trades, with considerable commodities, ranging between raw materials and energy to high-value manufactured products, being shipped between global economic powerhouses [FU, X. W., NG, A. K. Y., LAU, Y. Y., forthcoming, The impacts of maritime piracy on global economic development: The case of Somalia. Maritime Policy and Management]. Maritime security management, including the definition of security, maritime risk assessment, security measures, the regulation and policy of maritime security in shipping and port-related business operations has been receiving growing attention, both in practice and research.     

Roll-induced bifurcation in ship maneuvering under model uncertainty

In this paper, a mathematical model is developed for the maneuvering motion of a naval ship and bifurcations of its equilibrium are identified in roll-coupled motion. The subject ship is a high-speed surface combatant with twin-propeller twin-rudder system. Captive model tests are conducted for the ship using planar motion mechanism. Maneuvering coefficients are calculated by polynomial curve fitting of the test data. Uncertainty distribution in the coefficients is assumed same as that of the curve fitting errors. Uncertainty in the model coefficients is propagated to full-scale simulation results by the stochastic response surface method (SRSM). This method is computationally efficient as compared to standard Monte Carlo simulation technique. The SRSM uses polynomial chaos expansion of orthogonal to fit any probability distribution. Bifurcation analysis of the mathematical model is performed by varying the vertical center of gravity as the bifurcation parameter. Hopf bifurcation is identified. It is found that the bifurcations occur due to the coupling of roll motion with sway, yaw motion and rudder angle. In the presence of wind, roll angle response in bifurcation diagram is discussed.     

水火弯板残余变形预报的数值和量纲分析(英文)

Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed equations is only 60 to 90 seconds).     

Combining driver response with cyclical queue optimisation over selected corridors

A case study located in Auckland, New Zealand, was used to quantify the magnitude of savings that may result if the SCATS adaptive traffic control system contains an explicitly combined queue estimation and offset adjustment on a cycle‐by‐cycle basis. A validated SATURN traffic model was used to evaluate five scenarios that represent the short‐run and long‐run efficiency gains resulting from progressive signal adaption with an objective of queue minimisation on the main corridors. Optimisation was applied both area‐wide, and on selected arterial corridors, using a combined split/offset optimisation routine with responsive driver behaviour to achieve a network‐wide and corridor‐specific efficiency gain. The modelling heuristic evaluates the efficiency of both the Equisat and P₀ optimisation policies that would mimic a more progressive adaption of signals under SCATS. Results for the long‐run area‐wide optimisation can produce network‐wide travel‐time savings in the order of 20% and a reduction in transient queues of 28% if only selected corridors are optimised, with a 5% reduction in journey time over an average 8‐min journey. Copyright © 2016 John Wiley & Sons, Ltd.     

Estimation of bus dwell time using univariate time series models

A significant proportion of bus travel time is contributed by dwell time for passenger boarding and alighting. More accurate estimation of bus dwell time (BDT) can enhance efficiency and reliability of public transportation system. Regression and probabilistic models are commonly used in literatures where a set of independent variables are used to define the statistical relationship between BDT and its contributing factors. However, due to technical and monetary constraints, it is not always feasible to collect all the data required for the models to work. More importantly, the contributing factors may vary from one bus route to another. Time series based methods can be of great interest as they require only historical time series data, which can be collected using a facility known as automatic vehicle location (AVL) system. This paper assesses four different time series based methods namely random walk, exponential smoothing, moving average (MA), and autoregressive integrated moving average to model and estimate BDT based on AVL data collected from Auckland. The performances of the proposed methods are ranked based on three important factors namely prediction accuracy, simplicity, and robustness. The models showed promising results and performed differently for central business district (CBD) and non‐CBD bus stops. For CBD bus stops, MA model performed the best, whereas for non‐CBD bus stops, ARIMA model performed the best compared with other time series based models. Copyright © 2014 John Wiley & Sons, Ltd.     

Behavioral modeling of on-demand mobility services: general framework and application to sustainable travel incentives

Transportation - This paper presents a systematic way of understanding and modeling traveler behavior in response to on-demand mobility services. We explicitly consider the sequential and yet...     

Diagnosis and excision of breast multi-focal lesions by ultrasound-guided vacuum-assisted biopsy: a comparative evaluation

Objective To compare and evaluate the efficacy of diagnosis and excision for appropriately selected breast multi-focal lesions and solitary lesion by ultrasound-guided vacuum-assisted biopsy (UGVAB). Methods Among 392 appropriately selected patients, 187 patients with multi-focal lesions and 205 patients with solitary lesion were treated by the 8-gauge UGVAB from May 2007 to June 2009. All lesions were removed as completely as possible. The patients with benign pathology underwent physical and ultrasound examinations at one week and 6 months after procedure. Results During the procedure, only three patients had vasovagal syncope and twenty others complained of other intraoperative discomfort. An accurate pathological diagnosis was obtained in all lesions. There was no apparent false-negative result among the 696 lesions with benign pathology at a follow-up of 6 months after procedure. The rates of malignant or premalignant pathology, postoperative complications and residual lesions in patients with multi-focal lesions were higher than those in patients with solitary lesion. If each lesion was considered as a subject of study, there was no significant difference between the two groups. Conclusion UGVAB is an effective method for diagnosis and excision of appropriately selected breast multi-focal lesions and can be used routinely.     

A fuzzy logic‐based variable speed limit controller

Variable speed limit (VSL) is an emerging intelligent transportation system (ITS) measure to improve operational and safety performance of motorway systems. Rule‐based algorithms have been widely used in VSL applications because of their comprehensibility and ease of application. However, most of the algorithms proposed in the literature under this category are rather rough for the speed control. Pre‐specified rules show some difficulties in appropriately activating/deactivating control actions in real time because of non‐stationary and nonlinear nature of the traffic system. This paper proposes a fuzzy logic‐based VSL control algorithm as an alternative to the existing VSL control algorithms. The proposed algorithm uses fuzzy sets instead of crisp sets to allow the separation of attribute domains into several overlapping intervals. The discretization using fuzzy sets can help to overcome the sensitivity problem caused by crisp discretization used in the existing VSL algorithms. The proposed algorithm is assessed for a test bed in Auckland using AIMSUN micro‐simulator and verified against a well‐known VSL algorithm. The simulation results show that the proposed algorithm outperforms the existing one to improve the efficiency performance of the motorway system with the critical bottleneck capacity increased by 6.42% and total travel time reduced by 12.39% when compared to a no‐control scenario. Copyright © 2015 John Wiley & Sons, Ltd.     

Integrated population synthesis and workplace assignment using an efficient optimization-based person-household matching method

Transportation - Large scale activity-based simulation models inform a variety of transportation and planning policies using models that often rely on fixed or flexible workplace location in a...     

Overcoming Governance and Institutional Barriers to Integrated Coastal Zone,Marine Protected Area,and Tourism Management in Sri Lanka

One of the major barriers to addressing complex social–ecological issues through integrated coastal management (ICM) is a lack of intergovernmental coordination and cooperation (horizontal and vertical fragmentation). This article describes an effort to overcome the barriers to ICM in Sri Lanka by fostering intergovernmental collaboration and initiating adaptive governance to restore one town, Hikkaduwa, and its associated marine protected area (MPA) and coastal zone habitats. Administrators from 12 national and local governmental agencies that are responsible for aspects of coastal management in the town of Hikkaduwa participated in a series of formal and informal workshops and a week-long tour of ICM projects in the Philippines. Outcomes demonstrate that these informal and formal meetings, workshops, and travel experiences fostered trust, social capital, and attitudinal organizational commitment (AOC). The experiences motivated members to overcome vertical and horizontal governance fragmentation through the formation of an independent intergovernmental committee for the restoration of Hikkaduwa into a sustainable and resilient community. ICM activities undertaken by the newly formed organization suggest that internal leadership capacity, effective local–national partnerships, explicitly linked ecological–economic projects, and long-term commitment are necessary conditions for success. Overall, attainment of sustainability and resilience through successful ICM should be thought of as a journey and not a destination.