Impact of tsunamis on wave energy converters

With an increasing emphasis on renewable energy resources, wave power technology is fast becoming a realistic solution. However, the recent tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed creating large destructive waves. The question posed here is whether a nearshore wave energy converter (WEC) could withstand the force of an incoming tsunami. WECs of this type are usually located close to the boundary of dominance between linear and non linear e ects. An analytical 3D model is developed within the framework of a linear theory and applied to an array of xed plates [1]. The time derivative of the velocity potential allows the hydrodynamic force to be calculated, and the hydrostatic force can be calculated from the di erence in free surface heights on either side of the device. Results show that the loading for a typical tsunami is invariant with depth and maximum loading is felt at the center of the plate. By comparison with the loading from a typical swell, it is shown that the maximum force of a tsunami on a nearshore WEC will be approximately one hundreth of the magnitude of a regular sea state. We therefore conclude that an array of WECs will withstand a tsunami. A preliminary study on the non linear e ects on nearshore WECs, in particular the e ects of a sloping sea bed and multiple waves, is attempted through a comparison between the velocities of resonant and non resonant states. If after the rst wave recedes the device is left on dry land, a second wave may act as a shock on the plate and do more damage than it would to a partially submerged device. This e ect is demonstrated using a two dimensional non linear shallow water solver,VOLNA [2]. It is believed that dangerous con gurations could be found with more detailed investigations

The Force of a Tsunami on a Wave Energy Converter

With an increasing emphasis on renewable energy resources, wave power technology is fast becoming a realistic solution. However, the recent tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed creating large destructive waves. The question posed here is whether a nearshore wave energy converter (WEC) could withstand the force of an incoming tsunami. The analytical 3D model of Renzi & Dias (2012) developed within the framework of a linear theory and applied to an array of fixed plates is used. The time derivative of the velocity potential allows the hydrodynamic force to be calculated.Comment: 12 pages, 6 figures, 2 tables, 16 references. Paper presented at the ISOPE-2012 conference. Other author's papers can be downloaded at http://www.lama.univ-savoie.fr/~dutykh

On the use of finite fault solution for tsunami generation problems

The present study is devoted to the problem of tsunami wave generation. The main goal of this work is two-fold. First of all, we propose a simple and computationally inexpensive model for the description of the sea bed displacement during an underwater earthquake, based on the finite fault solution for the slip distribution under some assumptions on the dynamics of the rupturing process. Once the bottom motion is reconstructed, we study waves induced on the free surface of the ocean. For this purpose we consider three different models approximating the Euler equations of the water wave theory. Namely, we use the linearized Euler equations (we are in fact solving the Cauchy-Poisson problem), a Boussinesq system and a novel weakly nonlinear model. An intercomparison of these approaches is performed. The developments of the present study are illustrated on the 17 July 2006 Java event, where an underwater earthquake of magnitude 7.7 generated a tsunami that inundated the southern coast of Java.Comment: 31 pages, 10 figures, 3 tables. Other author's papers can be downloaded at http://www.lama.univ-savoie.fr/~dutykh

On the effect of compressibility on the impact of a falling jet

At the first World Sloshing Dynamics Symposium that took place during the Nineteenth (2009) International Offshore and Polar Engineering (ISOPE) Conference in Osaka, Japan, it was made clear that simplified academic problems have an important role to play in the understanding of liquid impacts. The problem of the impact of a mass of liquid on a solid structure is considered. First the steady two-dimensional and irrotational flow of an inviscid and incompressible fluid falling from a vertical pipe, hitting a horizontal plate and flowing sideways, is considered. A parametric study shows that the flow can either leave the pipe tangentially or detach from the edge of the pipe. Two dimensionless numbers come into play: the Froude number and the aspect ratio between the falling altitude and the pipe width. When the flow leaves tangentially, it can either be diverted immediately by the plate or experience squeezing before being diverted. The profile of the pressure exerted on the plate is computed and discussed. Then the same problem is revisited with the inclusion of compressibility effects, both for the falling liquid and for the gas surrounding it. An additional dimensionless number comes into play, namely the Mach number. Finally, a discussion on the differences between the incompressible and compressible cases is provided

Can clusters theory help realize Cyprus’s desire to develop centres of educational excellence?

This paper aims at exploring the various factors which could play a synergic role in the formation of a cluster system to support the development of higher education services as a competitive business endeavour. It proposes that Porter’s cluster dynamics might be applied to education in Cyprus in order that it might grow a regionally competitive sector within the Region. This is a goal set out in the Government’s Strategic Development Plan (1999-2003) and is brought into clearer focus with the accession of Cyprus to the EU in May 2004. Indicative evidence of clustering is presented based on the UK’s Research Assessment Exercise and policy issues are discussed for the Cyprus Government.peer-reviewe

A Probabilistic Spatial Distribution Model for Wire Faults in Parallel Network-on-Chip Links

High-performance chip multiprocessors contain numerous parallel-processing cores where a fabric devised as a network-on-chip (NoC) efficiently handles their escalating intertile communication demands. Unfortunately, prolonged operational stresses cause accelerated physically induced wearout leading to permanent metal wire faults in links. Where only a subset of wires may malfunction, enduring healthy wires are leveraged to sustain connectivity when a partially faulty link recovery mechanism is utilized, where its data recovery latency overhead is proportional to the number of consecutive faulty wires. With NoC link failure models being ultimately important, albeit being absent from existing literature, the construction of a mathematical model towards the understanding of the distribution of wire faults in parallel on-chip links is very critical. This paper steps in such a direction, where the objective is to find the probability of having a “fault segment” consisting of a certain number of consecutive “faulty” wires in a parallel NoC link. First, it is shown how the given problem can be reduced to an equivalent combinatorial problem through partitions and necklaces. Then the proposed algorithm counts certain classes of necklaces by making a separation between periodic and aperiodic cases. Finally, the resulting analytical model is tested successfully against a far more costly brute-force algorithm

The Role of Exporters’ Emotional Intelligence in Building Foreign Customer Relationships

Despite the critical importance of emotional intelligence in effectively interacting with other people, its role has been overlooked in scholarly research on cross-border interorganizational relationships. Drawing on Emotion Regulation Theory, we propose a model that conceptualizes links among exporters’ emotional intelligence, key behavioral dimensions characterizing the atmosphere of the relationship with import buyers, and the resulting relational performance. We test the model with data collected from 262 Greek exporters using structural equation modeling. The results indicate that higher levels of exporter emotional intelligence enhances communication and social bonding with the importer, while diminishing distance and conflict in their working relationship. Relational performance is positively influenced by communication and social bonding, but negatively affected by distance and conflict. The results also reveal the moderating effect of both opportunism and interpartner incompatibility on the association between the exporter’s emotional intelligence and the behavioral atmosphere of the relationship with import buyers

Femtosecond and UV inscribed grating characterization in photonic crystal fibres:optimization for sensing applications

Photonic crystal fibres (PCF) and more commonly microstructure fibres, remain interesting and novel fibre types and when suitably designed can prove to be "ideal" for sensing applications, as the different geometrical arrangement of the air holes alters their optical wave-guiding properties, whilst also providing tailored dispersion characteristics. This impacts the performance of grating structures, which offer wavelength encoded sensing information. We undertake a study on different air hole geometries and proceed with characterization of fibre Bragg and long period gratings, FBG and LPG, respectively that have been inscribed (using either a femtosecond or ultraviolet laser system) within different designs of microstructured fibre that are of interest for sensing applications

The impact of proximity on consumer fair trade engagement and purchasing behavior : the moderating role of empathic concern and hypocrisy

The article reports the findings of an empirical study among consumers, regarding the impact of physical, social, and psychological proximity on their engagement to the fair trade idea and purchasing behavior. Based on a random sample of 211 British and 112 Indian consumers and using structural equation modeling, it was found that high levels of physical, social, and psychological proximity leads to high consumer fair trade engagement. Moreover, consumer fair trade engagement was confirmed to have a positive impact on fair trade purchasing behavior. Furthermore, consumer empathic concern was found to positively moderate the association between proximity and consumer fair trade engagement, while the opposite was true with regard to consumer hypocrisy. Finally, consumer nationality was found to have a control effect on physical, social, and psychological proximity, with the latter felt stronger among Indian, as opposed to British consumers