True Service Yard - New Business Model for Shipyards - working paper

co-authored with Rebic N. and Golik Klanac N. and presented at the Economist: Ideas Economy Conference at Berkeley 2011. The presented model was selected by the Economist amongst the TOP4 business models for 2011.

The existing “product-oriented” business model of shipyards is focused on production and on the sales of ships to the owners according to their specifications. This has a consequence that yards permanently operate with large capital, but without proper security, as their onshore assets (land, cranes, infrastructure, documentation and workforce) are worth only a fraction e.g. of their annual income. With the rising competition putting pressure on the ship prices, the premium for running such a business diminishes. If the yards do not posses large sums of cash, eventually they meet the crisis and are often forced to default. The proposed “service-oriented” model removes the need for cash back-up. By renting ships, instead of selling, the yards would significantly increase their assets and achieve not only a continuous, but also a less risky income. One should bear in mind here that a customized ship, built according to owner specifications, is both the prototype and the final product, so attaining quality and meeting deadlines is often hazardous. Favourable and unfavourable internal and external factors that the proposed model could achieve are closely examined in the shipyards SWOT analysis.

Economics and environmental impact of ships speed reduction for the VLCC tanker

technical report, co-authored with P. Nikolic and P. Kumar

In this study we analyse the economic effects and environmental impact of speed reduction for a VLCC tanker. Ship emissions participate in the global CO2 emissions with 3,3%, SOx are emitted at around 4% of world total, while the NOx are about 7% of all total emissions. According to the European Union targets these levels of emissions need to be drastically reduced already in 2020. By varying the speed and the installed power, considering also the effects of fuel consumption difference, market conditions and the increase in transportation time, it is shown that slow steaming can be simultaneously economically sound and eco-friendly. Furthermore, are indicated scenarios in which slow steaming ship can be more profitable than the ship operating at the standard service speed. Changes in the environmental efficiency design index, or EEDI, are also addressed.

Design method for safe ship structures

Doctoral thesis manuscript (corrected proof; full version with published papers)

At present ships are designed to satisfy the minimum requirements for safety. And history shows that this practice does not suffice, and nor is it sustainable. A new paradigm is needed. This thesis aims to contribute in that respect by proposing a design method that should move ship safety beyond the minimum requirements as much as possible and as long as it is economically sound. The thesis focuses mostly on environmental safety in the event of accidents such as collisions and grounding. A special feature is the consideration of maritime stakeholder preferences regarding safety and profitability. This is an underlying element in all the analysis performed and conclusions reached.
This design method features new approaches in multi-objective optimization of ship structures and in advanced decision making for design selection. The multi-objective optimization is based on evolutionary algorithms, more precisely the genetic algorithm (GA) with advanced treatment of design constraints and objectives. Through the approach of vectorization, the GA becomes not only more efficient, but also more flexible in use, bearing in mind the complexity and demands of accident analysis for optimization. The decision making is established on the concepts of Game Theory, resulting in a new criterion for design selection, the Competitive Optimum, based on the maximal concurrent satisfaction of stakeholder preferences.
The proposed design method is intended in particular for ship structural design projects, permitting the definition of hull structural scantlings, or even hull topology if desired. The approaches to multi-objective optimization and design selection that are introduced possess a wider basis of application, and are extensible to other fields in maritime safety and naval architecture.
The results of the thesis provide several relevant conclusions with an impact on practical naval architecture. For example, i) by increasing ship crashworthiness, significant risk reduction can be attained, ii) raising safety is economically justified if the benefits to the public are considered alongside those of the industry, and iii) the crashworthiness of ships can be controlled effectively with conventional double-bottom and double-sided structures.

ECONOMICS AND ENVIRONMENTAL IMPACT OF SHIP SPEED REDUCTION FOR AFRAMax TANKERS

co-authored with Petar Nikolic, Maja Kovac and Jonathan McGregor; published in Proc. XIX SORTA 2010.

In this study we analyse the economic effects and environmental impact of speed reduction for an AFRAMax tanker. By varying the speed and the installed power, considering also the effects of fuel consumption difference, market conditions and the increase in transportation time, we show that slow steaming can be simultaneously economically sound and eco-friendly. Changes in the environmental efficiency design index, or EEDI, are also addressed.

Vectorization and constraint grouping to enhance optimization of marine structures

Co-author: Jasmin Jelovica, published in 'Marine Structures' 2008

Vectorization converts classical scalar optimization formulation, which strictly separates the objective from constraints, into a vector-based optimization, transforming constraints into objectives. Effectively, the search is not conducted anymore for a single optimum, but for a set of Pareto optima between the original objective and transformed constraints. Constraint grouping enhances handling of multiple constraints for vectorized problems, by combining several constraints within a single objective function, thus reducing the computational time and computational difficulties of high-dimensional spaces created by vectorization. This paper formulates and investigates these two concepts with respect to design of marine structures. It analyses their effects on the possibility to improve the flexibility of optimization in a practical environment, by implementing them within a simple genetic algorithm. Obtained results of vectorization applied to realistic weight optimization problem are encouraging when compared with the results of the classical scalar form optimization, showing a significant improvement in magnitude as well as in reduced computation time needed to reach the optimum.

Multi-stakeholder decision-making in the risk-based of a Ro-Pax double bottom for grounding

co-authors: Risto Jalonen, Petri Varsta; published in Journal of Engineering for the Maritime Environment in 2007

Grounding accidents can be fatal for ships. This paper discusses decision-making in the risk-based design to avoid such outcomes for a 30000 GT RO-PAX in a powered hard grounding. Five alternatives of a double bottom structure are suggested to reduce the risks of loss of life, environmental damage and material damage. Risk assessment concentrates on the consequences, applying numerical grounding simulations to model the energy absorption of proposed alternatives. To determine the risks, 1295 Monte Carlo simulations are performed running a quasi-static model of ship motions. Accounting for these risks and the added production costs and operational loss, a new multi-stakeholder approach for selecting alternatives is proposed assuring simultaneous maximal satisfaction to both the shipyard and the ship owner. As an outcome, two alternatives are selected, the first increasing the bottom shell thickness by 50%, and the second, increasing the stiffness of longitudinal stiffeners by 90%. If observing their performance, it is possible to recommend the latter as the most-effective solution. Such outcome is in accordance with the established practical opinions in increasing safety for grounding, proving sagacity of the presented approach.

Vectorization in the structural optimization of a fast ferry

Co-author: Jasmin Jelovica, published in 'Shipbuilding' in 2007.

Vectorization assumes conversion of constraints into objective functions. It generalizes single-objective, or scalar, optimization into a search for a Pareto optimal set, which will enhance the search for the optimum. Vectorization is studied here within a structural optimization of fast ferry’s midship section for the minimum of steel weight. Optimization applies simple genetic algorithm (GA), which performance is observed over both scalar and vectorized problem formulations. The obtained results show that the applied GA can improve the referenced design, and that the improvement can be significantly better using vectorization.

Design Optimization of Steel Sandwich Hoistable Car-Decks Applying Homogenized Plate Theory

Jani Romanoff, Alan Klanac, published in 'J Ship Production', 2006.

This paper describes an approach for concept design of laser-welded web-core steel sandwich panels. The me-thod utilizes a newly developed theory for the bending response of laser-welded web-core sandwich plates. Structural optimization is carried out using enumeration and newly developed vectorization-based Genetic Algo-rithm. To demonstrate these concepts, a case study in design of a hoistable car-deck is considered. Finally, the optimization is conducted considering the objectives of deck weight.

Stress analysis of homogenized web-core sandwich beams

Jani Romanoff, Petri Varsta, Alan Klanac, published in 'Composite Structures', 2007

his paper presents a stress analysis method for web-core sandwich beams. The beam is a transverse cut from a sandwich plate. The analysis is carried out by transforming the initially periodic web-core sandwich beam, constructed from a set of unit cells, into an equivalent homogenous sandwich beam. Certain deformation components are set equal both in periodic and homogenous beams when a unit cell is considered. The structural analysis of the homogenized beam follows thick face plate kinematics giving the deflection, bending moment and shear force distributions. Then the normal stress components can be calculated accurately by reconsidering the periodic structure of the beam. The validation of the proposed method is carried out with FE-analyses.

Steel Sandwich Panels in Marine Applications

Kujala, P. and Klanac, A. Published in journal of Shipbuilding 2005

Steel sandwich panels welded by laser can offer 30-50 % weight savings compared to the conventional steel structures. Helsinki University of Technology/Ship Laboratory has done active research during the past 10 years on various topics related to the laser welded steel sandwich panels. The work carried out includes development of design formulations for the ultimate and impact strength, analysis of fatigue strength for the joints, and development of solutions to improve the behaviour under fire. A number of research projects both at the national and European level have been ongoing. In the paper, a summary of the marine applications, main benefits and problem areas of the panels as well as available design tools are given. A case study for weight and cost optimisation of a hoistable cardeck is also presented proving some of the described benefits of all steel sandwich panels.

A Concept for Concurrent Design of Ships

Frank D, Klanac A, Bralic S. Published in Proceeding of COMPIT'08, Liege 2008

By successfully integrating different design tools, ship design can be enhanced to fully approach a concurrent activity. Such a joint platform enables a creation of a virtual model of a ship which encompasses different functionalities supporting designers. Joint platform, named nG.ZINE, acts through a flexible XML database, storing and on-demand supplying current and previous values of significant ship parameters, allowing designers to concurrently accommodate the variations created by their colleagues. It does so without a demand for changes in either designers working environment, or in the tools it integrates. nG.ZINE applies the multi-stakeholder decision-making, a multi-attribute and group decision-making concept.

A concept of omni-optimization for ship structural design

Klanac, A. Jelovica, J. Advancements in Marine Structures, Guedes Soares & Das (eds), Proceedings of MARSTRUCT 2007, The 1st International Conference on Marine Structures, 12-14 March 2007, Glasgow, UK. p. 473-481. (Taylor & Francis: London).

Omni-optimization assumes a capability to perform any type of optimization, e.g. single- and multi-objective, using single optimization algorithm, or the omni-optimizer. This paper addresses a novel concept for omni-optimization, by coupling vectorization with genetic algorithms (GAs). Vectorization assumes converting constraints into objectives, and their optimization alongside the original set of objectives. The GAs show excellent potential to serve as omni-optimizers, as they are a successful tool to solve both single- and multi-objective problems. This new concept is applied to structural design of the midship section of an 88m long aluminium fast ferry for the minimal hull weight and vertical centre of gravity (VCG), under multiple constraints involving structural and technological aspects and classification rules and regulations. The obtained results range up to 10 per cent for weight minimization and 6.5 per cent for VCG with the fully defined Pareto front.

Qualitative design assessment of crashworthy structures

Klanac, A., Ehlers, S., Tabri, K., Rudan, S., Broekhuijsen, J. Qualitative design assessment of crashworthy structures, Proceedings of International Maritime Association of Mediterranean - IMAM, Lisboa 2005, p. 461-9.

Safety at sea is the vivid motivator for naval architects to design structures absorbing higher amounts of energy in case of collisions or grounding. This paper brings a qualitative assessment of 10 different steel sandwich alternatives to identify potential novel crashworthy side shell structures. First, the design alternatives are evaluated for crashworthiness under consistent conditions in a numerically simulated test pro-cedure, followed by the estimation of production costs. On the basis of performance over these two attributes one design is selected for second stage for further study in more realistic conditions. Namely, it is integrated in two variants into a section of an inland waterway tanker which is collided with a rigid bow. The results are compared with the performance of a conventional double side. One variant of a novel structure offered 40 % higher capacity to absorb collision energy.

ng.zine - A NEW DESIGN SYSTEM FOR NAVAL ARCHITECTURE

Frank, D. Klanac, A. Bralic, S. Proc. SORTA, Pula, 2008.

Present day ship design is faced with a difficulty to successfully integrate multiple design tools. This paper introduces ng.zine, a new design system intended for conceptual and preliminary ship design, aiming to make the design tool integration easy. ng.zine acts through the flexible XML database, storing and on-demand supplying current and previous values of significant ship parameters and attributes. It does so without a demand for changes in either designers working environment, or in the tools it integrates, leading to the increased flexibility of the design process. ng.zine permits a parallel execution of multiple design tasks. To assure efficient control and management, ng.zine applies concepts of group decision-making. Every designer is supported in choosing the proper parameter values with respect to the particular task responsibility and the global ship performance. Considered concepts allow designers to model in their experiences, knowledge and organizational hierarchy.

Structural Omni-Optimization of a Tanker

Co-authoer with Jelovica J, Niemeläinen M, Domagallo S, Remes H, Romanoff J and published in proceedings of COMPIT '08 conference

Omni-optimization assumes a capability to perform several types of optimization, e.g. single- and multi-objective, using the same optimization algorithm, or the omni-optimizer. Here we consider omni-optimization to investigate the capabilities of a proposed structural arrangement of a 40 000 DWT chemical tanker. The interest is to gain more knowledge about the capabilities of this arrangement and optimize it for reduction in weight and increase in safety. Omni-optimization is performed with a simple genetic algorithm though the re-formulated ‘vectorized’ structural optimization problem. The overall process is managed through Matlab where also the structural response and strength calculations are performed.

Optimization of crashworthy marine structures

co-authored with Sören Ehlers and Jasmin Jelovica. Accepted for publication in Marine Structures

History shows that ferry and RoPax collisions with tankers can be devastating for human life. This paper follows up such scenario to study rational increase of safety of tanker structures. Through the coupling of multi-objective structural optimization and crashworthiness analysis, a conventional tanker structure is optimized for higher collision tolerance, accounting also for the hull mass, so that the increase in safety is rational. Two new concepts are proposed for this task: a crash simulations approach utilizing coarse FE mesh to reduce the simulation’s calculation time and a two-stage optimization approach which seeks to minimize the number of collision simulations and thus reduce the overall optimization time. Combining the results with the state-of-the-art knowledge, new reasoning about crashworthiness of tanker structures is realized.

Vectorization In the Structural Optimization of a Fast Ferry

Optimal Design of Steel Sandwich Panel Applications In Ships

DESIGN OF MARINE STRUCTURES WITH IMPROVED SAFETY FOR ENVIRONMENT

co-authored with Petri Varsta, accepted for publication in 'Reliability Engineering and System Safety'

The paper describes a method for design of marine structures with increased safety for environment, considering also the required investment costs as well as the aspects of risk distribution onto the maritime stakeholders. Practically, the paper seeks to answer what is the optimal amount that should be invested into certain safety measure for any given vessel. Due to the uneven distribution of risk, as well as the differing impact of costs emerging safety improvements, stakeholders experience conflicting ranking of alternatives. To solve this multi-stakeholder decision-making problem, in which each stakeholder is a decision-maker, the method applies concepts of group decision-making theory, namely the Game Theory. The method fosters axiomatic definition of the optimum solution, arguing that the solution, or the final selected design, should satisfy the non-dominance, efficiency, and fairness. These three are thoroughly discussed in terms of structural design, especially the latter. Considering the coupling of environmental risk and structural design, the method also builds on the preference structure of four maritime stakeholders: yards, owners, oil receivers and the public, who either share the risks or directly influence structural design. Method is presented on a practical study of structural design of a tanker with a crashworthy side structure that is capable of reducing the risk of collision. The outcome of this study outlines a number of possibilities for successful improvement of tanker safety that can benefit, concurrently, all maritime stakeholders.