Unified Octonionic Representation of the 10-13 Dimensional Clifford Algebra

We give a one dimensional octonionic representation of the different Clifford algebra Cliff(5,5)\sim Cliff(9,1), Cliff(6,6)\sim Cliff(10,2) and lastly Cliff(7,6)\sim Cliff(10,3) which can be given by (8x8) real matrices taking into account some suitable manipulation rules.Comment: RevTex file, 19 pages, to be published in Int. J. of Mod. Phys.

Beach and cliff retreat induced by storm groups at Forte Novo,Algarve (Portugal)

Littoral cell dynamics may change through time as a reaction to modifications of the coastal system. Along the Vilamoura-Quarteira coastline, the construction of a groin field limited the sediment supply to the already narrow Forte Novo beach, located downdrift, enhanced wave action on the cliff base and lead to long-term persistent cliff retreat. This research uses a set of surveys from November 2009 to March 2010 to determine short-term soft cliff erosion associated to storm groups at this sediment starved area. Following the initial LiDAR survey, three subsequent surveys were performed using a reflectorless total station for monitoring the cliff face, and RTK-DGPS to monitor the position of the cliff top, the cliff foot and the topography of the adjacent beach. Results indicate an important reduction in beach levels during successive storms (without significant beach recovery in between), allowing waves to further attack the cliff base and contributing to further enhance the structural and permanent cliff retreat. This work demonstrates how a combination of magnitude and frequency of extreme events coupled with development of the coastline, has led to increased cliff-beach recession and to the permanent dislocation of the cliff face

Cliff retreat and sea bed morphology under monochromatic wave forcing: Experimental study

Wave flume experiments have been performed to investigate a sandy cliff recession under monochromatic wave forcing. We varied the wave climate through the wave energy flux F and the surf similarity parameter j. The various processes of the cliff erosion cycle are depicted. The sea bed evolution mostly depends on the surf similarity parameter j. Steep planar (j > 0.7), gentle planar (0.5 < j < 0.7) and bared (j < 0.5) profiles are observed. We observed different bar dynamics, including steady and unsteady self-sustained oscillating states. Then we analyze the role of the eroded material on the cliff recession rate. We show that the cliff recession rate increases with the wave energy flux. Moreover, for a given wave energy flux, it is larger for a gentle planar profile than for a bared profile. However it is similar for both a bared profile and a steep planar profile. The cliff recession rate is not a monotonic function of the cliff height as the type of bottom profile influences the wave energy at the cliff

Disentangle plume-induced anisotropy in the velocity field in buoyancy-driven turbulence

We present a method of disentangling the anisotropies produced by the cliff structures in turbulent velocity field and test it in the system of turbulent Rayleigh-B\'{e}nard (RB) convection. It is found that in the RB system the cliff structures in the velocity field are generated by thermal plumes. These cliff structures induce asymmetry in the velocity increments, which leads us to consider the plus and minus velocity structure functions (VSF). The plus velocity increments exclude cliff structures, while the minus ones include them. Our results show that the scaling exponents of the plus VSFs are in excellent agreement with those predicted for homogeneous and isotropic turbulence (HIT), whereas those of the minus VSFs exhibit significant deviations from HIT expectations in places where thermal plumes abound. These results demonstrate that plus and minus VSFs can be used to quantitatively study the effect of cliff structures in the velocity field and to effectively disentangle the associated anisotropies caused by these structures.Comment: 10 pages, 5 figure

Coastal cliff ground motions and response to extreme storm waves

Coastal cliff erosion from storm waves is observed worldwide, but the processes are notoriously difficult to measure during extreme storm wave conditions when most erosion normally occurs, limiting our understanding of cliff processes. Over January–February 2014, during the largest Atlantic storms in at least 60 years with deepwater significant wave heights of 6–8 m, cliff-top ground motions showed vertical ground displacements in excess of 50–100 µm; an order of magnitude larger than observations made previously. Repeat terrestrial laser scanner surveys over a 2 week period encompassing the extreme storms gave a cliff face volume loss of 2 orders of magnitude larger than the long-term erosion rate. The results imply that erosion of coastal cliffs exposed to extreme storm waves is highly episodic and that long-term rates of cliff erosion will depend on the frequency and severity of extreme storm wave impacts

Niełatwa archeologia klifów – przypadek stanowisk w Bagiczu

The following paper presents the problem of archaeological sites located on cliffs on the Southern Baltic Sea shore. This article discusses issues related to a necessity of solving the problem of this kind of research, related to methodological, as well as documentation and preservation standards based on preliminary results of the project conducted in Bagicz area (Ustronie Morskie commune). In this region four new structures were noted on a cliff surface. The key to understand the situation of archaeological sites located on a cliff areas is the knowledge of the processes related to their formation and activity. All of them have a huge impact for the state of preservation of the cliff, however they have various intensity level depending on the part of the Baltic Coast.The following paper presents the problem of archaeological sites located on cliffs on the Southern Baltic Sea shore. This article discusses issues related to a necessity of solving the problem of this kind of research, related to methodological, as well as documentation and preservation standards based on preliminary results of the project conducted in Bagicz area (Ustronie Morskie commune). In this region four new structures were noted on a cliff surface. The key to understand the situation of archaeological sites located on a cliff areas is the knowledge of the processes related to their formation and activity. All of them have a huge impact for the state of preservation of the cliff, however they have various intensity level depending on the part of the Baltic Coast

Modelling failure mechanisms of soft cliff profiles

A large proportion of the 11,000 km coastline of the United Kingdom is backed by soft cliffs. These cliffs are subject to frequent slumping and landslip events, particularly where sea and ground water percolates into the soil and rock. Many of these cliffs are formed from glaciogenic sediments, which experience severe erosion and rapid recession with long-term horizontal recession rates typically up to 2-3 m/year. A series of scaled physical model tests have been conducted using a large centrifuge facility with two-dimensional cliff models. These were tested in a wave flume container located on the centrifuge. Wave loading was created using a quasi-flap paddle system that was located at the opposite end of the centrifuge box. A number of tests were conducted using different cliff materials (i.e. combinations of sand and Portland cement). A parametric study was carried out to assess the influence of variations in cliff geometry and height, soil properties, wave amplitude and period. From these tests, it has been found that generally, failures occurred by progressive undercutting of the cliff toe, followed by global failure of the cliff mass