Staved construction in furniture

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An application of fuzzy-AHP to ship operational energy efficiency measures

Lowering fuel consumption of ships has gained a great deal of attention in maritime industry with regards to both environmental and economic concerns. The potential for fuel economy in shipping ranging between 25% to 75% is possible by using existing technology and practices and technical improvements in the design of new ship. Despite the existence of many technology and design-based approaches, limitations of emerging these measures has led to discussions about the potential energy savings through operational changes. In this study, operational measures were examined within the scope of Ship Energy Efficiency Management Plan (SEEMP) adopted by International Maritime Organization (IMO). We applied the Analytic Hierarchy Process (Fuzzy-AHP) approach, one of multi-criteria decision making (MCDM) techniques, to prioritize the weight of each measure. Fuzzy AHP effectively reflects the vagueness of human thinking with interval values, and shows the relative importance of operational measures - which can be the fundamental decision making data for decision makers (ships' masters, operating companies and ship owners) - by providing a strategic approach to identify energy efficient solutions

Design of robust slow-speed ships for sustainable operation

Phd ThesisMulti-objective optimisation that considers the energy efficiency and economic success is an important aspect of ship design and operation. Both the hydrodynamic and economic performance characteristics need to be addressed in the early stages of the design, and secured during the life span of a ship. Because of the conflicting nature of these two objectives, there are various trade-offs at stake in the goal for making ships more efficient and greener to comply with IMO regulations while reducing the building and operating costs and increasing the profitability at the same time for all stakeholders especially owners and operators. In attempt to reduce the amount of greenhouse gas emissions from ships, and hence to achieve a lower EEDI value, this research approaches the problem of improving the energy efficiency of ships. That is achieved by optimising the hull design over a speed range through parametric modification to reduce resistance and required power, and also through adopting slow steaming concept. Moreover, the research aims to determine the best practice to reduce the annual cost of running a ship and to increase the annual revenue as well as to make the ship a more profitable investment over her life span. The profit per tonne.mile and the net present value NPV are estimated in the economic analysis to be used as indicators to compare alternative designs for different routes and market conditions scenarios. To achieve this aim, the main operational and economic aspects such as the fluctuations in the fright rates and fuel prices in the shipping market are covered in the economic analysis. In addition, the acquiring price and salvage value are included in order to obtain solid comparisons. An optimisation framework using a VBA macro code has been developed based on the concept of Pareto optimality to assess decision making, and to determine robust designs as well as operational profiles based on results from the hydrodynamic model, environmental impact model, and the economic model. The optimisation process is carried out for a Panamax tanker case study using 5 parameters and a set of constraints for the hull parameters and speed. The outcome from the optimisation framework is a set of Pareto optimal solutions where weight factors are appointed to give the flexibility when addressing the importance of each individual function. The solutions are presented graphically to form what is known as Pareto front which determines the design space and the trade-offs between the different competing objective ii functions. This optimisation framework could assist decision making where it is possible to choose a robust design or designs that offer a near-optimum performance regardless any fluctuations in the market and or the operation profile, and eliminate any significant sub-optimal design

A cost estimation analysis of U.S. Navy fuel-saving techniques and technologies

The U.S. Department of Defense and Navy are placing a greater emphasis in energy efficiency. Though the surface fleet comprises only a small percentage of petroleum usage, seemingly small efficiencies gained could yield substantial fuel savings. This thesis follows a process of researching and collecting fuel-saving ideas, developing a method to estimate savings, subjecting calculations to sensitivity analyses by discount factor and cost of fuel, and creating prioritization listings of ideas based on predicted savings. Six technique and twelve technology-based initiatives are examined. Calculations are estimated for each idea using inputs from various sources. Sensitivity analysis is performed on the independent variables of fuel price and discount factor and rankings are computed. The prioritized listing of techniques and technologies are stable when subjected to these sensitivity analyses. And as expected, greater savings are realized when the cost of fuel is higher and/or when the discount factor is lower. For several of the practices in this study, fuel savings are shown to be substantial and worthy for consideration despite any involved risk. These findings may be used by decision makers to pursue further testing and evaluation of practices and subsequently confidently implement throughout the surface fleet, knowing that savings will remain robust despite fluctuations in fuel prices.http://archive.org/details/acostestimationn109454515US Navy (USN) author.Approved for public release; distribution is unlimited

The VLCC tanker market : the present, past and future : a historical fleet analysis followed by a stochastic partial equilibrium model of the spot freight market

This thesis analyzes the development of the VLLC fleet over the last two decades. On the basis of collected data, the supply curves of the current and historical fleets are calculated under three distinguished speed regimes; speed optimized regime, fixed speed at maximum speed and fixed speed at 12 knots. We then proceed with the current fleet and construct a partial equilibrium model of the spot freight market. Our model incorporates a stochastic process surrounding bunker price, demand, scrapping and new building. The model is applied to simulate the probability distribution of the future spot rates under the different speed regimes. Finally we find the short-term distribution of the spot rate when demand is high and low

The welfare cost of lawlessness: evidence from Somali piracy

In spite of general agreement that establishing the rule of law is central to properly functioning economies, little is known about the cost of law and order breakdowns. This paper studies a specific context of this by estimating the effect of Somali piracy attacks on shipping costs using data on shipping contracts in the dry bulk market. To estimate the effect of piracy, we look at shipping routes whose shortest path exposes them to piracy and find that the increase in attacks in 2008 led to around an 8% to 12% increase in costs. From this we calculate the welfare loss imposed by piracy. We estimate that generating around 120 USD million of revenue for Somali pirates led to a welfare loss in excess of 630 USD million, making piracy an expensive way of making transfers

Optimizing Ship Speed to Minimize Total Fuel Consumption with Multiple Time Windows

We study the ship speed optimization problem with the objective of minimizing the total fuel consumption. We consider multiple time windows for each port call as constraints and formulate the problem as a nonlinear mixed integer program. We derive intrinsic properties of the problem and develop an exact algorithm based on the properties. Computational experiments show that the suggested algorithm is very efficient in finding an optimal solution

The Implications and trade-offs of near-port ship emissions reduction policies

Maritime shipping is considered the most efficient mode of transport in economic and environmental terms. However, its impacts on climate change through greenhouse gas emissions and on human health from air pollutants released near residential centres cannot be ignored. Over the last decades, regulatory bodies have been developing policies that seek to further improve the sector’s environmental performance and at the same time new technologies improve the efficiency of vessels. Operational practices of shipliners and port authority initiatives are also relieving the sector’s impacts. While there has been significant research on the environmental impacts of maritime transport, there has been relatively little work focusing on the effects of maritime activity in the proximity and at ports. This thesis presents a transferable framework that allows the estimation of emissions pollutant generation near the port focusing on CO2, SO2, NOx and BC emissions. The most relevant emissions reduction actions are considered and their effects on the environmental footprint of the port are modelled. The thesis emphasizes on the implementation of speed reduction programmes near the port, use of cold ironing at berth, and the effects of fuel quality regulation, considering the perspectives of the port authority, and the ship operator. The thesis considers the emerging environmental and economic trade-offs due to the different emissions reduction actions. A non-linear convex optimization model is formulated that minimizes fuel consumption in a sequence of port calls where in some areas speed limits or fuel regulations are in place. The results show that there is no universal port policy that can simultaneously minimize the environmental impact of all ships without economic or environmental penalties. This indicates that there is great scope of improvement in existing policies, and that regulators will need to decide what their priorities should be in improving the system. The achievements of this thesis can be beneficial to policy makers, port authorities, and shipping companies that wish to improve their environmental performance without sustaining environmental and economic penalties to do so.Open Acces

Influence of mixed flows on ship hydrodynamics in dredged channels

Although there is a significant body of research devoted to the shallow water hydrodynamic aspects of ships, several unexamined topics remain. Among these is that of critical outer flow in a dredged channel and its influence on parameters of interest. While empirical methods can be used with ease to resolve this, they can provide results with reliability sufficient only for an early design stage. On the other hand, more sophisticated potential flow theories are either inapplicable or do not perform well at the critical limit. However, RANS (Reynolds Averaged Navier-Stokes) – based tools can accurately capture all underlying phenomena without relying on limiting assumptions. This paper presents an attempt at comparing some results obtained via a CFD-based RANS solver and the slender body theory for critical outer flow in a dredged channel