Étude quantitative de l'érosion en aval des dissipateurs d'énergie type auge

2002 ◽  
Vol 29 (2) ◽  
pp. 201-210 ◽  
Author(s):  
A El Amri ◽  
J L Verrette
Keyword(s):  
Energy Dissipation ◽  
The Other ◽  
Scale Model ◽  
Small Scale ◽  
Other Hand ◽  
Energy Dissipators ◽  
The Impact ◽  
Small Scale Model ◽  
Impact Distance

Scour tests on downstream roller bucket energy dissipators have shown that, at the equilibrium, bed characteristics are mainly influenced by the discharge and by the height of the bucket lip. The discharge affects scour characteristics, without however modifying the shape of the bed. On the other hand, the height of the bucket lip simultaneously affects scour characteristics and the shape of the bed mainly in the vicinity of the structure. In the latter area, for larger values of the height of the bucket lip, one observes a deposition with a small depression on the top and, on the contrary, when the height of the bucket lip is small, one observes an erosion. Both the depth of scour and the thickness of the deposit increase proportionally to the height of the bucket lip. Values of the other bed characteristics decrease slightly with the height of the bucket lip to reach a minimum, then they increase for higher values of the height of the bucket lip. Comparison of bed characteristics at the equilibrium with the literature shows that theory overestimates the depth of the scour measured in the laboratory by an average of 68% for the three values of discharge, underestimates the impact distance by about 6% for low discharges, and overestimates it by 10% for the highest discharge.Key words: hydraulic energy dissipation, roller bucket, scour mecanism, scour, small-scale model.

Effects of type of flow, plants and addition of organic carbon in the removal of zinc and chromium in small-scale model wetlands

2007 ◽  
Vol 56 (3) ◽  
pp. 199-205 ◽  
Author(s):  
D. Paredes ◽  
M.E. Vélez ◽  
P. Kuschk ◽  
R.A. Mueller
Keyword(s):  
Organic Matter ◽  
Removal Rate ◽  
Typha Latifolia ◽  
Surface Flow ◽  
Synthetic Wastewater ◽  
Scale Model ◽  
Small Scale ◽  
Significant Difference ◽  
The Impact ◽  
Small Scale Model

Constructed wetlands are used for the treatment of wastewater containing metals. In order to clarify the role of plants, flow and the impact of organic matter, an investigation of three factors, each at two different levels, was carried out in small-scale model wetlands. The evaluated factors and levels were: type of flow (subsurface and surface); presence of plants (planted with Typha latifolia and unplanted) and addition of organic matter (with and without). Eight different experimental units were run for a year. The units were fed with synthetic wastewater containing chromium (VI) (1.5 mg L−1), zinc (1.5 mg L−1), macro, micronutrients and organic matter (to those units in which this factor was being investigated). Subsurface flow wetlands showed a significantly higher rate of chromium removal in comparison with surface flow systems (97 and 60 mg m−2 d−1, respectively). Planted systems removed significantly more chromium compared to unplanted systems (85 and 76 mg m−2 d−1, respectively), and the addition of organic matter increased the removal rate in a comparison with the units without it (88 and 69 mg m−2 d−1, respectively). Similar results were found for zinc; however, the addition of organic matter made no significant difference to zinc removal.

Parameter Identification of a Steel Catenary Riser Using Hilbert and Wavelet Transforms

2015 ◽  
Author(s):  
Lizeth Torres ◽  
Cristina Verde ◽  
Flavia Borges ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Wavelet Transforms ◽  
The Other ◽  
Scale Model ◽  
Modal Parameters ◽  
Small Scale ◽  
Damping Factor ◽  
Steel Catenary Riser ◽  
Campos Basin ◽  
Mdof Systems ◽  
Small Scale Model

This article presents a methodology — for Multiple Degree of Freedom (MDOF) systems — to identify the modal parameters of a steel catenary riser (SCR) by employing both the Hilbert and the wavelet transforms. To validate the proposed approach, a set of experiments were performed in a small scale model of a real SCR that is installed in the P18 platform operating in Campos Basin, Brazil. During the experiments, the damping factor along the SCR was modified by adding viscoelastic sandwich layers on its structure. Each change was recorded with two accelerometers mounted at the bottom of the riser; one of them was set to get measurements in the catenary plane and the other one to get measurements out of the plane. Then, in order to obtain the impulse response of the structure — from which is possible to obtain the modal parameters — some hammer impacts were applied at locations close to these accelerometers.

scholarly journals DYNAMIC SIMILARITY OF TRANSPORT PHENOMENA

1980 ◽  
Vol 1 (17) ◽  
pp. 158
Author(s):  
M.S. Yalin ◽  
F. Gerritsen
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Physical Modelling ◽  
The Other ◽  
Scale Model ◽  
Small Scale ◽  
Separation Processes ◽  
Densimetric Froude Number ◽  
Ocean Environment ◽  
Small Scale Model

The discharges issued by OTEC plants, thermal power plants and other engineering devices, give rise to the transport of "foreign" properties and substances into the natural ocean environment. In order to predict the functioning of such structures and assess their environmental impact, physical modelling has already been utilized. Since the simultaneous fulfillment of both Reynolds and Froude criteria is impossible (in a conventional small scale model operating with the prototype fluid) in the models mentioned the transport phenomenon was reproduced on the basis of the densimetric Froude number (Fr) only, the influence of the Reynolds number (Re) being neglected. On the other hand, the identification of the scale of Fr (viz Apr) with unity can lead to substantial differences between the model and prototype values of Re. (Because AFr = 1 yields AR6 = Ax 3/2 where Xjt is the linear model scale.) Yet many of the pertinent aspects of a turbulent diffusion (energy dissipation, thickness of mixing zones, separation processes, etc.) are strongly dependent on Re, and therefore an appreciable distortion of Re (AJJ3/2

scholarly journals The role of agribusiness in stimulating on-farm investments – case-study of the armenian dairy sector

2012 ◽  
Vol 6 (1-2) ◽  
pp. 85-91 ◽  
Author(s):  
Liesbeth Dries ◽  
Matthew Gorton ◽  
John White ◽  
Vardan Urutyan ◽  
Gagik Sardaryan
Keyword(s):  
Policy Implications ◽  
The Other ◽  
Small Scale ◽  
Investment Activity ◽  
International Firms ◽  
Contractual Arrangements ◽  
Other Hand ◽  
Supply Policy ◽  
The One ◽  
The Impact

This paper analyses the impact on investments of contractual arrangements between farms and agribusiness in the Armenian dairy sector. Our empirical evidence is based on a unique survey of 300 Armenian dairy farms. The dairy sector is of particular importance as it provides vital employment and income, in an environment of weak social security and scarce job opportunities. Furthermore, milk production is predominantly organized in small-scale farms, which are most likely to be affected by adversarial financial conditions and limited in their opportunities to raise resources to invest. The results show that a large share of milk producers in Armenia is actively investing to upgrade their farm business. Furthermore, investment activity is not limited to large dairy farmers as over 30% of respondents with less than eight cows have made dairy-specific investments. We find that the linkages between farms and agribusiness – and more specifically the support programs that agribusiness firms offer to their suppliers – have been crucial in stimulating this restructuring process at the farm level. Interestingly, farmers with a more exclusive relationship to the buyer and farmers that deliver to more internationally oriented buyers are more likely to receive support. On the other hand, buyers that operate in a more competitive market are less likely to provide support to their suppliers. These findings have interesting policy implications. On the one hand, our results point to the gains that can be made from openness to international firms. On the other hand, the negative competition effect indicates that buyers are unable to enforce repayment of the provided farm services in an environment where a lot of buyers are competing for the same supply. Policy makers should look at ways of improving the enforcement capability of dairy companies under these circumstances.

scholarly journals Diffraction and reflection of irregular waves in a harbor employing a spectral model

2009 ◽  
Vol 81 (4) ◽  
pp. 837-848 ◽  
Author(s):  
Nelson Violante-Carvalho ◽  
Rafael B. Paes-Leme ◽  
Domenico A. Accetta ◽  
Frederico Ostritz
Keyword(s):  
Coastal Waters ◽  
Wave Model ◽  
The Other ◽  
Irregular Waves ◽  
Scale Model ◽  
Small Scale ◽  
Swan Model ◽  
Relevant Role ◽  
Incident Waves ◽  
Small Scale Model

The SWAN wave model is widely used in coastal waters and the main focus of this work is on its application in a harbor. Its last released version - SWAN 40.51 - includes an approximation to compute diffraction, however, so far there are few published works that discuss this matter. The performance of the model is therefore investigated in a harbor where reflection and diffraction play a relevant role. To assess its estimates, a phase-resolving Boussinesq wave model is employed as well, together with measurements carried out at a small-scale model of the area behind the breakwater. For irregular, short-crested waves with broad directional spreading, the importance of diffraction is relatively small. On the other hand, reflection of the incident waves is significant, increasing the energy inside the harbor. Nevertheless, the SWAN model does not achieve convergence when it is set to compute diffraction and reflection simultaneously. It is concluded that, for situations typically encountered in harbors, with irregular waves near reflective obstacles, the model should be set without the diffraction option.

SCENARIOS FOR AN EXPANDING DEMAND OF TOURISM ON THE COASTS OF CUBA

2017 ◽  
Author(s):  
Oscar Gutiérrez-Bolívar ◽  
Oscar Gutiérrez-Bolívar ◽  
Pedro Fernández Carrasco ◽  
Pedro Fernández Carrasco
Keyword(s):  
United States ◽  
The Other ◽  
Sudden Increase ◽  
Tourist Destination ◽  
Other Hand ◽  
The Usa ◽  
The Impact

The opening of relationships between United States and Cuba could be a drive for a huge increase in the affluence of tourism to Cuba and especially to the coast areas. Cuba has been for many years an important tourist destination for people from many countries, but almost forbidden for US citizens. The proximity of the USA, its amount of population as well as their great acquisition power will increase in a very substantial way the demand for accommodation and other uses in the proximity of the coasts. There will be a need to implement a package of measures that reduce the impact of such sudden increase in the coastal line. On the other hand that augment in tourism could be an opportunity to improve the standard of life of Cubans. The consideration of different possibilities of such development, the analysis of the damages that each one could cause as well as the measures that could avoid, ameliorate or compensate such effects are the goals that are going to be presented in this paper.

Laughter on the Fringes

2019 ◽  
Author(s):  
Anna Peterson
Keyword(s):  
The Other ◽  
Literary Canon ◽  
Autobiographical Writing ◽  
Treasure Trove ◽  
Old Comedy ◽  
Other Hand ◽  
Aggressive Humor ◽  
The One ◽  
The Individual ◽  
The Impact

This book examines the impact that Athenian Old Comedy had on Greek writers of the Imperial era. It is generally acknowledged that Imperial-era Greeks responded to Athenian Old Comedy in one of two ways: either as a treasure trove of Atticisms, or as a genre defined by and repudiated for its aggressive humor. Worthy of further consideration, however, is how both approaches, and particularly the latter one that relegated Old Comedy to the fringes of the literary canon, led authors to engage with the ironic and self-reflexive humor of Aristophanes, Eupolis, and Cratinus. Authors ranging from serious moralizers (Plutarch and Aelius Aristides) to comic writers in their own right (Lucian, Alciphron), to other figures not often associated with Old Comedy (Libanius) adopted aspects of the genre to negotiate power struggles, facilitate literary and sophistic rivalries, and provide a model for autobiographical writing. To varying degrees, these writers wove recognizable features of the genre (e.g., the parabasis, its agonistic language, the stage biographies of the individual poets) into their writings. The image of Old Comedy that emerges from this time is that of a genre in transition. It was, on the one hand, with the exception of Aristophanes’s extant plays, on the verge of being almost completely lost; on the other hand, its reputation and several of its most characteristic elements were being renegotiated and reinvented.

scholarly journals Analysis of Operational Efficiencies and Costs for Extracting Thinned Woods in Small-Scale Forestry, Nasunogahara Area, Tochigi Prefecture, Japan

2020 ◽  
Vol 3 (1) ◽  
pp. 61
Author(s):  
Kazuhiro Aruga
Keyword(s):  
Transportation Costs ◽  
The Other ◽  
Small Scale ◽  
Light Truck ◽  
Operation Costs ◽  
Other Hand ◽  
Light Trucks ◽  
The Cost ◽  
Manual Extraction ◽  
Truck Transportation

In this study, two operational methodologies to extract thinned woods were investigated in the Nasunogahara area, Tochigi Prefecture, Japan. Methodology one included manual extraction and light truck transportation. Methodology two included mini-forwarder forwarding and four-ton truck transportation. Furthermore, a newly introduced chipper was investigated. As a result, costs of manual extractions within 10 m and 20 m were JPY942/m3 and JPY1040/m3, respectively. On the other hand, the forwarding cost of the mini-forwarder was JPY499/m3, which was significantly lower than the cost of manual extractions. Transportation costs with light trucks and four-ton trucks were JPY7224/m3 and JPY1298/m3, respectively, with 28 km transportation distances. Chipping operation costs were JPY1036/m3 and JPY1160/m3 with three and two persons, respectively. Finally, the total costs of methodologies one and two from extraction within 20 m to chipping were estimated as JPY9300/m3 and JPY2833/m3, respectively, with 28 km transportation distances and three-person chipping operations (EUR1 = JPY126, as of 12 August 2020).

scholarly journals Application of Plant Extracts in Micropropagation and Cryopreservation of Bleeding Heart: An Ornamental-Medicinal Plant Species

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 542
Author(s):  
Dariusz Kulus ◽  
Natalia Miler
Keyword(s):  
Tissue Culture ◽  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Plant Extracts ◽  
The Other ◽  
White Gold ◽  
Natural Extracts ◽  
Other Hand ◽  
The Impact

Lamprocapnos spectabilis (L.) Fukuhara (bleeding heart) is valued both in the horticultural and pharmaceutical markets. Despite its great popularity, information on the in vitro tissue culture technology in this species is limited. There is also little knowledge on the application of plant extracts in the tissue culture systems of plants other than orchids. The aim of this study is to compare the utility of traditional plant growth regulators (PGRs) and natural extracts—obtained from the coconut shreds, as well as oat, rice, and sesame seeds—in the micropropagation and cryopreservation of L. spectabilis ‘Gold Heart’ and ‘White Gold’. The biochemical analysis of extracts composition is also included. In the first experiment related to micropropagation via axillary buds activation, the single-node explants were cultured for a 10-week-long propagation cycle in the modified Murashige and Skoog medium fortified either with 1.11 µM benzyladenine (BA) and 1.23 µM indole-3-butritic acid (IBA) or with 10% (v/v) plant extracts. A PGRs- and extract-free control was also considered. In the cryopreservation experiment, the same 10% (v/v) extracts were added into the medium during a seven-day preculture in the encapsulation-vitrification cryopreservation protocol. It was found that the impact of natural additives was cultivar- and trait-specific. In the first experiment, the addition of coconut extract favoured the proliferation of shoots and propagation ratio in bleeding heart ‘Gold Heart’. Rice extract, on the other hand, promoted callus formation in ‘White Gold’ cultivar and was more effective in increasing the propagation ratio in this cultivar than the conventional plant growth regulators (4.1 and 2.6, respectively). Sesame extract suppressed the development of the explants in both cultivars analysed, probably due to the high content of polyphenols. As for the second experiment, the addition of plant extracts into the preculture medium did not increase the survival level of the cryopreserved shoot tips (sesame and oat extracts even decreased this parameter). On the other hand, coconut extract, abundant in simple sugars and endogenous cytokinins, stimulated a more intensive proliferation and growth of shoots after rewarming of samples. Analysing the synergistic effect of conventional plant growth regulators and natural extracts should be considered in future studies related to L. spectabilis.

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