Advanced Materials Research Vol. 1036

Abstract: The proposed idea of the integration methodology is based on the two basic pillars it is the modified functional model of the manufacturing process plan and a product intermediate states representation. The product state in certain moment of the manufacturing process can be identified by a set of states which describe the current status of the manufacturing process advance for particular manufacturing features. On the other hand from a manufacturing process nature results that during its course a product can be at one of the following states after rough, medium and finishing manufacturing treatment. Information about product states makes the full integration between CAPP and CAP systems possible. The proposed methodology allows reacting to unexpected production process disturbances. In this case the CAP system in cooperation with manufacturing execution system MES, which collects production data just from PLCs controllers, communicates with CAPP system in the feedback loop and sends a set of the product intermediate states. Base on this description the CAPP system redesign a manufacturing process plan taking into account the current product state. In the paper the modified functional model of the technological process plan and the method of product intermediate states are presented. Moreover the proposal of the functional schema of the integrated CAD/CAPP/CAP environment is shown.

Abstract: In the paper a survey of predictive and reactive scheduling methods is done in order to evaluate how ability of prediction of reliability characteristics influence over robustness criteria. Survey analysis is done for two job shop scheduling problems: 5x8 and 5x10. The paper answers the question: what method generates robust schedules in case of a failure of a bottleneck occurrence before or after maintenance actions The Hybrid - Multi Objective Immune Algorithm (H-MOIA) is aided with heuristics: Minimal Impact of Disturbed Operation on the Schedule (MIDOS) for predictive scheduling and Minimal Impact of Rescheduled Operation on the Schedule (MIROS) for reactive scheduling. Sensitivity analysis is done for predictive scheduling methods 1) H-MOIA +MIDOS, 2) algorithm based on priority rules: the Least Flexible Job First (LFJ) and the Longest Processing Time (LPT) and 3) the Average Slack Method. Reactive schedules are generated for various scenarios of the bottleneck occurrence in order to evaluate the efficiency of predictive scheduling methods. Reactive schedules are generated using 1) H-MOIA+MIROS, 2) Right Shifting, 3) rescheduling disturbed operations to parallel machines first available. Efficiency of predictive schedules is evaluated using criteria: makespan, total tardiness, flow time, idle time. Efficiency of reactive schedules is evaluated using: solution robustness criterion and quality robustness criterion.

Abstract: A queueing system of the M/M/1/N type with cyclic failure-free and repair times is used as a model of a single-machine manufacturing line. Jobs arrive according to a Poisson process and are being served with exponentially distributed processing time. Successive working (failure-free) and repair times have exponential distributions, too. Basing on a system of integral equations for double transforms of conditional probability distributions of the number of jobs completely processed before the fixed time (departure process), comprehensive numerical analysis of the impact of system parameters on the mean number of departures before the fixed epoch T>0 is carried out.

Abstract: This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

Abstract: Wave energy conversion technology has known a worldwide magnitude in the last decades due to the implementation of international norms of reducing of pollutant emissions owed by production of electricity. The paper intends to carry out a comparative analysis between mechanical and electrical analogy, for a more precisely determination of parameters that have a influence on oscillating system with floating bodies for waves energy capture.

Abstract: Ship motion forecasting is very important for safety of ships especially when operating in offshore mooring state. It is known that the ship motions have dynamical and nonlinear characteristics in the ocean and sea environments. In our paper we try to predict the manoeuvrability of the ships applying the predicted nonlinear wave field with the current state of the vessel motions using ship course time series prediction, which is based on back propagation neural network structure and algorithm, was proposed. The results of simulations performed by means of the elaborated networks are given in comparison with test simulations cases for different value of rudder angle. This method was applied to ship manoeuvrability prediction, and simulation results showed the validity to improving the prediction accuracy.

Abstract: The container carrier shipping industry faces nowadays a similar phenomenon that happened in the 90s with crude oil carriers: an imaginable gigantism not-forecasted even by the most optimistic specialists. In the last 20 years the demand in transportation by containers continuously grew. The reaction of Carriers was quick under this demand growth and began an exacerbate competition not only in size of their fleets but in the size of their vessels as well. Before building a new vessel, a set of simulations and tests of prototypes and models is done, in order to apply corrections of the initial projects but, the practice showed that each vessel is different and its behavior at sea, too. In order to be acquainted to dealing with the various situations at sea, the true measurements of the vessels performance are done in her sea trials. The purpose of this paper is to update this Sea trials process, to detail it and to bring the contemporary element: measurement technologies, calculations, mathematical models.

Abstract: The changes increasingly accentuated in recent years in the global economy, in the context of globalization, have created an environment in which transport sector must adapt continuously. This adaptation process acts especially at intercontinental level, involving that transport and distribution of goods and raw materials on long distances to be as efficient in terms of duration and costs of transport and, at the same time, with reduced negative implications on the environment. The achievement of transport processes, in equilibrium conditions between demand and supply, in relation to limitations mentioned above, is possible by promoting intermodal transport, which requires a very good connection between continental modes (road and rail transport) and shipping. According to European Commission, about 90% of total import / export trades at the level of European Union are done by maritime transport. This paper aims at identifying potentials of generation / attraction of travels made on road transport at the level of intermodal node represented by seaport of Constanta. These trips generation / attraction potentials may be further used as input data in dimensioning processes of intermodal logistics facilities (handling, storage and internal transport) between road and sea transport modes. In the frame of the study are processed and analyzed data obtained through origin - destination surveys conducted during general traffic census carried out in 2010, on the network of European, national and county roads of Romania. Also, were processed data regarding types and volumes of goods transited through this port in the period 2005-2010, and the types of ships used to load these goods. Statistically analyzing these two types of data, it was revealed that grain represents 34% and petroleum products 57% of all goods (in terms of weight) handled in the seaport of Constanta, and also that the continental transport mode predominantly used to move these categories of goods is road transport. The results of performed analyzes, that describe the current situation regarding the trade flows in the port unit, constitute the starting point in traffic modeling for the purpose of freight transport planning at future time moments. Models for traffic estimation in ports take into account the predictions about economic development in influence area on short, medium and long terms.

Abstract: One of the most frustrating problems when dealing with risks it’s that they come in so many different forms. They can appear at any point in a port logistic system, they can interrupt the supply of raw materials or products, they can cause demand fluctuations (peak or collapse), inventory problems (lack or crowding), dispatch delay. Risks can range on a scale from small delay to a natural disaster, from short term to a permanent damage, with effects localized on a part of a supply chain or affecting the whole chain activity. The risk management allows port administration to take appropriate measures to reduce the consequences of a risk, to provide a good reliability of the logistic system or to design a resilient one. The paper investigates the major risks in port logistics and adequate measures to minimizing their effects. A risk management tree is set-up. Using computer simulation modelling, a case study investigates the port logistic system behaviour under different risk scenarios and evaluates the reliability of the system and its resilience. The operation capacity for different port logistics sub-system is assessed taking into consideration the required operating standards and the measures of performance (e.g. waiting time for vessels and transport vehicles, storage area and time for commodities) of the logistic system are computed.

Abstract: Radio frequency identification (RFID) is one of the most actual techniques employed to control the circuit of merchandises, as an alternative to the classical barecode. RFID tags should be cheap and easy to reproduct on a multitude of dielectric supports. There are several types of RFID systems, depending on whether tag and/or reader are active or passive. For cost reasons, merchandise identification should use active reader and passive tag, as the latter might be manufactured on a cheap FR4 support or printed directly on paper, by using a conductive ink. Passive tags can be shaped as straight dipoles, meandered dipoles, or loops. When a small area is required, loops are more appropriated. Codes are made different one from another by using on the same tag antennas with different resonance frequencies. Another advantage of loops is that they can be placed one inside other, so the occupied area is even smaller compared to other multi-resonant tags. Firstly, a single loop is analyzed, in order to model the resonant behaviour, correlated to the loop geometry and size. Open and closed loops are studied; the lowest resonance frequency for a given loop length is achieved for the open loop. In that case, the loop is resonating as a dipole. Next, a tag with three concentric loops is investigated. Separately, a small loop is used on the tag, in order to couple the received power in a resistor. When the tag is close to the reader, the latter is triggered if power is absorbed simultaneously on the three expected frequencies. The proposed tag was simulated and manufactured. Results show a good agreement between measured and simulated data. Finally, a block diagram for the reader was proposed.