Vol. 27 No. 2 (2015)
Ünal ÖZDEMİR, Abdulaziz GÜNEROĞLU
2015 (Vol 27), Issue 2
It is commonly accepted that the majority of maritime causalities are caused by human factors/errors. The role of human factor in maritime accident and the possible reasons of this argument can be quantitatively evaluated based on expert knowledge and multiple criteria decision-making (MCDM) methodology. To investigate what makes the first “human factor” in ship accidents, a hybrid approach was applied in this study. Two methods, the decision-making trial and evaluation laboratory (DEMATEL) and the analytical network process (ANP) were proposed to evaluate the importance level of the human factors in maritime casualties. Quantitative evaluations of the human errors in maritime operations can greatly improve the decision-making process and reduce potential risks. As a result of this study, the top three priorities in the evaluation systems were found as: ‘ability, skills, knowledge’ (8.94%), ‘physical condition’ (8.77%), ‘weather - sea conditions’ (8.21%) and the least important criterion was ‘cargo characteristics’ (2.21%).
Zhibin Jiang, Chao Xie, Tingting Ji, Xiaolei Zou
2015 (Vol 27), Issue 2
Understanding the nature of rail transit dwell time has potential benefits for both the users and the operators. Crowded passenger trains cause longer dwell times and may prevent some passengers from boarding the first available train that arrives. Actual dwell time and the process of passenger alighting and boarding are interdependent through the sequence of train stops and propagated delays. A comprehensive and feasible dwell time simulation model was developed and optimized to address the problems associated with scheduled timetables. The paper introduces the factors that affect dwell time in urban rail transit systems, including train headway, the process and number of passengers alighting and boarding the train, and the inability of train doors to properly close the first time because of overcrowded vehicles. Finally, based on a time-driven micro-simulation system, Shanghai rail transit Line 8 is used as an example to quantify the feasibility of scheduled dwell times for different stations, directions of travel and time periods, and a proposed dwell time during peak hours in several crowded stations is presented according to the simulation results.
Svetlana Nikoličić, Milorad Kilibarda, Predrag Atanasković, Ljubica Duđak, Andrea Ivanišević
2015 (Vol 27), Issue 2
The challenges that logistics faces in the retail industry must be investigated in the context of the specific retail sector as well as the degree of development of the retail market. The research focus in this paper is on logistic processes in supermarket supply. The aim is to deepen the understanding of logistic processes and then to investigate the possibilities of their enhancement by applying radio frequency identification (RFID) as a higher level of information technology for product identification in retail supply chains. The research was conducted in one of the top ten trade companies in the emerging Serbian market. Simulation modelling was performed for one supply chain category, followed by quantification of time and cost performance of the current logistic processes (AS-IS model). Then, in accordance with the capabilities of RFID system, improvements are proposed and integrated into a new simulation model (TO-BE model). The obtained results can be utilised as part of a broader research when deciding on the implementation of modern information technologies in supply chains.
Mark E. Koryagin
2015 (Vol 27), Issue 2
An urban passenger transportation problem is studied. Municipal authorities and passengers are regarded as participants in the passenger transportation system. The municipal authorities have to optimise road width and public transport frequency. The road consists of a dedicated bus lane and lanes for passenger cars. The car travel time depends on the number of road lanes and passengers’ choice of travel mode. The passengers’ goal is to minimize total travel costs, including time value. The passengers try to find the optimal ratio between public transport and cars. The conflict between municipal authorities and the passengers is described as a game theoretic model. The existence of Nash equilibrium in the model is proved. The numerical example shows the influence of the value of time and intensity of passenger flow on the equilibrium road width and public transport frequency.
Martina Baučić, Damir Medak
2015 (Vol 27), Issue 2
The main objective of integrating Web GIS in airport emergency response should be to provide the most appropriate geospatial information to all participants. Airport emergency response still needs a model that will explain its complexity: its participants, their tasks and information needs. This paper presents the UML model of airport emergency response. Such a model facilitates a common understanding of the system by participants coming from airport, police, fire brigade, etc. It also enables institutional agreements for sharing data. The developers have got specifications of geospatial data and GIS functions imposed by participants and standards. A prototype Web GIS application is developed and presented to the users for evaluation. The prototype has shown how GIS functions can improve airport emergency response. The users have shown great interest, and they have great expectations in further integration of Web GIS in airport emergency response.
Bojan Jovanović, Katarina Mostarac, Dragana Šarac, Estera Rakić
2015 (Vol 27), Issue 2
This paper provides a preview of the former stages through which the market of express postal services had gone and the possibilities of further development, both on the global and local level. The aim of this paper is to complete an estimation of the need for this type of express services using the competitive Lotka–Volterra model in Serbia. In order to reduce the complexity of the process, the division of competition was conducted in two segments: the public operator and the private segment (comprised of all private operators). The given model provides a description of a dynamic competition relationship by indicating the existence of the equilibrium point between the public and the private sectors, and the conditions of its stability. The obtained values indicate that the private sector affects the public operator. The existing predator-prey relationship gives preference to the private sector and can be described by the Lotka-Volterra model.
Haifu Wang, Liangcai Cai, Xiaolei Chong, Hao Geng
2015 (Vol 27), Issue 2
A combined blast fence is introduced in this paper to improve the solid blast fences and louvered ones. Experiments of the jet engine exhaust flow (hereinafter jet flow for short) field and tests of three kinds of blast fences in two positions were carried out. The results show that the pressure and temperature at the centre of the jet flow decrease gradually as the flow moves farther away from the nozzle. The pressure falls fast with the maximum rate of 41.7%. The dynamic pressure 150 m away from the nozzle could reach 58.8 Pa, with a corresponding wind velocity of 10 m/s. The temperature affected range of 40°C is 113.5×20 m. The combined blast fence not only reduces the pressure of the flow in front of it but also solves the problems that the turbulence is too strong behind the solid blast fences and the pressure is too high behind the louvered blast fences. And the pressure behind combined blast fence is less than 10 Pa. The height of the fence is related to the distance from the jet nozzle. The nearer the fence is to the nozzle, the higher it is. When it is farther from the nozzle, its height can be lowered.
