Energy Efficiency Analysis of Trawlers (Case Study: Indonesian’s Trawler)

Nowadays, the energy efficiency is of most importance in all economical activities. For the fishing industry, it is particularly critical. Energy efficiency in the fishing sector can be expressed in term of the ratio of fishing capture over operational cost. The fuel cost in ship operation became a dominant factor of the total operational cost. Moreover, fuel cost is high and continues to increase. One way to achieve better energy efficiency is to use a high efficiency ship propeller in order to diminish fuel consumption.   Trawlers have two main operational conditions; they are the voyage condition and the trawling condition. The voyage condition is when the trawler travels to port and to the fishing grounds. The trawling condition is when the trawler pulls the trawl to catch fish. Most of trawler problem is in trawling operation with trawls, the ship resistance increased tremendously and then the propeller must work harder to ensure the ship can advance against the trawling resistance at low speed, 3, 5 Knots. This condition corresponds to a heavy load condition. In this condition, the propeller efficiency is low. Duct propeller is one of the configurations that increase the propeller efficiency in heavy loaded condition. The other strategy is to increase the energy efficiency is to optimize ship speed in voyage condition.  In this research, the numerical simulations performed for the propeller-duct interactions were made possible thank to an iterative procedure where the flow around each of the several components are modeled with a potential flow theory. Boundary element Method (BEM) or panel method is used to solve the potential flow model. The models and methods are described in the document as well as the iterative procedure that has been developed within the framework of this project. We have investigated energy efficiency with fuel consumption approach. Propeller with and without duct in same size (B3-65 and Kaplan 65 in Duct 19A) are analyzed and optimized ship speed 9 Knots to 7 Knots. It shows that 13.7 % of the fuel consumption was saved with a duct propeller in trawling condition and 35% of the fuel consumption was saved with an optimized ship speed in voyage condition

Design of composite ducted horizontal axis tidal turbine

The marine current turbine is the mechanical device that captures the kinetic energy of marine current to generate electrical power. A panel method program coupled with the blade element momentum theory (BEM) was used to design a bare tidal turbine which reaches 88% of the Betz limit. The addition of a duct for a same overall cross section area has been investigated. The numerical results show that the ducted turbine’s power coefficient, which was computed using the overall cross section area, can be slightly increased if a camber duct profile with a flare angle is used. The hydrodynamic pressure obtained with the panel method code were then implemented as boundary conditions to a finite element analysis (FEA) in order to compute the mechanical behavior, stress distribution and deflection of the duct in composite material. The Hashin criterion was used for damage prediction

Application of 2nd Generation Intact Stability Criteria on Naval Ships

The second generation intact stability criteria are currently under finalization and validation at the IMO. These criteria are organized in five stability failure modes and three levels of vulnerability assessment in each failure mode. Although this new regulation will not apply to naval ships, it is interesting to investigate the behavior of this vessel typology as well, due to their geometry and typical Froude number. This paper deals with of the pure loss of stability and parametric roll phenomena. Level one and level two vulnerability criteria for three naval ships of different size (helicopter carrier, destroyer, offshore patrol vessel) are applied. Results show an overall satisfactory behavior of the three ships investigated by the new regulation, for both failure stability modes

Velocity and confinement of edge plasmons in HgTe-based 2D topological insulators

High-frequency transport in the edge states of the quantum spin Hall (QSH) effect has to date rarely been explored, though it could cast light on the scattering mechanisms taking place therein. We here report on the measurement of the plasmon velocity in topological HgTe quantum wells both in the QSH and quantum Hall (QH) regimes, using harmonic GHz excitations and phase-resolved detection. We observe low plasmon velocities corresponding to large transverse widths, which we ascribe to the prominent influence of charge puddles forming in the vicinity of edge channels. Together with other recent works, it suggests that puddles play an essential role in the edge state physics and probably constitute a main hurdle on the way to clean and robust edge transport.Comment: 8 pages, 6 figures, + supplementary materia

Using whole-genome SNP data to reconstruct a large multi-generation pedigree in apple germplasm

Background Apple (Malus x domestica Borkh.) is one of the most important fruit tree crops of temperate areas, with great economic and cultural value. Apple cultivars can be maintained for centuries in plant collections through grafting, and some are thought to date as far back as Roman times. Molecular markers provide a means to reconstruct pedigrees and thus shed light on the recent history of migration and trade of biological materials. The objective of the present study was to identify relationships within a set of over 1400 mostly old apple cultivars using whole-genome SNP data (~253K SNPs) in order to reconstruct pedigrees. Results Using simple exclusion tests, based on counting the number of Mendelian errors, more than one thousand parent-offspring relations and 295 complete parent-offspring families were identified. Additionally, a grandparent couple was identified for the missing parental side of 26 parent-offspring pairings. Among the 407 parent-offspring relations without a second identified parent, 327 could be oriented because one of the individuals was an offspring in a complete family or by using historical data on parentage or date of recording. Parents of emblematic cultivars such as 'Ribston Pippin', 'White Transparent' and 'Braeburn' were identified. The overall pedigree combining all the identified relationships encompassed seven generations and revealed a major impact of two Renaissance cultivars of French and English origin, namely 'Reinette Franche' and 'Margil', and one North-Eastern Europe cultivar from the 1700s, 'Alexander'. On the contrary, several older cultivars, from the Middle Ages or the Roman times, had no, or only single, identifiable offspring in the set of studied accessions. Frequent crosses between cultivars originating from different European regions were identified, especially from the 19th century onwards. Conclusions The availability of over 1400 apple genotypes, previously filtered for genetic uniqueness and providing a broad representation of European germplasm, has been instrumental for the success of this large pedigree reconstruction. It enlightens the history of empirical selection and recent breeding of apple cultivars in Europe and provides insights to speed-up future breeding and selection