Performance improvement of a drag hydrokinetic turbine

Hydropower is at present in many locations, among all the other possible renewable energy sources, the best one for net cost per unit power. In contrast to traditional installation, based on water storage in artificial basins, free flow river turbines also provide a very low environmental impact due to their negligible effect on solid transport. Among them, kinetic turbines with vertical axis are very inexpensive and have almost zero impact on fish and local fauna. In application to tidal waves and sea waves, where vertically averaged velocities have alternate direction, a Savonius rotor also has the advantage of being productive during the whole time cycle. In this work, the effect of an upstream deflector system mounted upstream of a twisted Savonius rotor inside a channel has been investigated through numerical simulations and experimental tests. Numerical simulations were carried on using the ANSYS FLUENT 17.0 software. Based on this numerical study, it is shown that the proposed deflector system has improved the power coefficient of the Savonius rotor by 14%. The utilization of this new design system is predicted to contribute towards a more efficient use of flows in rivers and channels for electricity production in rural areas

Results of combined treatment of anaplastic thyroid carcinoma (ATC)

<p>Abstract</p> <p>Background</p> <p>Anaplastic thyroid carcinoma (ATC) is among the most aggressive human malignancies. It is associated with a high rate of local recurrence and with poor prognosis.</p> <p>Methods</p> <p>We retrospectively reviewed 44 consecutive patients treated between 1996 and 2010 at Leon Berard Cancer Centre, Lyon, France. The combined treatment strategy derived from the one developed at the Institut Gustave Roussy included total thyroidectomy and cervical lymph-node dissection, when feasible, combined with 2 cycles of doxorubicin (60 mg/m2) and cisplatin (100 mg/m2) Q3W, hyperfractionated (1.2 Gy twice daily) radiation to the neck and upper mediastinum (46-50 Gy), and then four cycles of doxorubicin-cisplatin.</p> <p>Results</p> <p>Thirty-five patients received the three-phase combined treatment. Complete response after treatment was achieved in 14/44 patients (31.8%). Eight patients had a partial response (18.2%). Twenty-two (50%) had progressive disease. All patients with metastases at diagnosis died shortly afterwards. Thirteen patients are still alive. The median survival of the entire population was 8 months.</p> <p>Conclusion</p> <p>Despite the ultimately dismal prognosis of ATC, multimodality treatment significantly improves local control and appears to afford long-term survival in some patients. There is active ongoing research, and results obtained with new targeted systemic treatment appear encouraging.</p

Las poáceas perennes: una alternativa para la rehabilitación y la restauración de pastos degradados en el Túnez presahariano

La magnitud de la presión humana sobre los pastos de la zona árida norteafricana se ha saldado con una rarefacción de las gramíneas perennes y la degradación de los suelos. Al ser la regeneración natural muy lenta es necesario plantearse el recurso de la reintroducción de especies locales rarificadas. El presente artículo examina la complementariedad de necesidades y comportamientos de dos gramíneas perennes de gran interés pastoral. Cenchrus ciliaris L., de origen tropical con fotosíntesis C4, de producción eminentemente en la estación cálida es interesante en años de pluviosidad favorable. Stipa lagascae Roem. & Shultes, especie C3 utiliza mejor el agua en períodos fríos. La mezcla de semillas de ambas especies complementarias en la utilización del agua, permite rehabilitar un pasto en el que el banco de semillas se haya agotado. La degradación de las propiedades físico-químicas del suelo, así como el acortamiento del periodo en que el agua del suelo está disponible para la vegetación, durante el verano, explican en parte la rarefacción de individuos de especies de origen tropical (caso de C. ciliaris) en beneficio de especies de origen mediterráneo ( caso de S. lagascae) en la flora de los pastos de la zona árida al norte del Sahara.Human pressure on North African ad pastures is causing soil degradation and rarefaction of perennial grasses. Artificial reintroduction of rarefied species can be an alternative in these areas, where spontaneous regeneration may be too slow. We have evaluated the ecological needs and performance of two perennial grasses with high grazing interest. Tropical Cenchrus ciliaris L. is a C4 that concentrates production during the warmest periods, and may be of particular interest in relatively wet years. Stipa lagascae Roem. & Shultes, is a C3 grass that may thrive under relatively cold conditions. Seeding mixes of these complementary species may contribute to rehabilitate grazing areas where the seed bank has been depleted. Soil degradation, and the reduction in the period when water is available during the summer, partly explain rarefaction of tropical species (as C. ciliaris) and gradual dominance of Mediterranean species (as S. lagascae) in northern Sahara arid pastures.L'ampleur de la pression humaine sur les parcours en zone aride Nord africaine s'est soldée par une raréfaction des graminées pérennes et une dégradation des sols. La régénération naturelle devenue très lente, il est nécessaire d'envisager le recours à la réintroduction d'espèces locales raréfiées. Le présent article examine la complémentarité des besoins et des comportements de deux graminées pérennes de grand intérêt pastoral. Cenchrus ciliaris L., d'origine tropicale, de type biochimique de photosynthèse en C4, et produisant surtout en saison chaude est intéressante en année à pluviosité favorable. Stipa lagascae Roem. & Shultes, espèce de type en C3 utilise mieux l'eau en période froide. Le semis en mélange de ces deux espèces complémentaires dans l'utilisation de l'eau, permet de réhabiliter un parcours, si les semenciers ont disparu. La dégradation des propriétés physico-chimiques du sol, ainsi que le raccourcissement de la durée des disponibilités en eau du sol pour la végétation, durant la période estivale, expliquent en partie la raréfaction des individus des espèces d'origine tropicale (cas de C. ciliaris) au profit des espèces d'origine méditerranéenne (cas de S. lagascae) dans la flore des parcours de la zone aride au Nord du Sahara

An Effective Localization Method for Robot Navigation Through Combined Encoders Positioning and Retiming Visual Control

The paper presents an optimal mobile robot localization method through encoders' measurements and absolute localization using webcam data. This technique has been developed and implemented for the motion of the robot from an initial position towards another desired position, taking into account Kinematic constraints. The proposed method is a cheap technique, which deals with the problem of robot initial position as the visual system provides the origin absolute coordinates related to the reference system. First, we have developed an interface, which ensures the real-time localization of the mini robot Khepera II while tracking a virtual moving target. Secondly, we have carried out experimentations of both the relative localization method, which determines the speed values of each driving wheel, and absolute localization using webcam data, which determines the robot start position. Next, a correction of the mobile robot position has been realized by retiming points using webcam measures. The obtained results are compared and discussed through different trajectories

Using Unconventional Methods to Control the Chaotic Behavior of Switched Time Systems: Application to a Stepper Motor

In this paper we suggest a method to control the chaotic behavior of the stepper motor into a periodic one. In fact, using the supply frequency as a bifurcation parameter, we show that as the frequency is increased beyond a critical value the motor steps become irregular and even chaotic hence it becomes unpractical to be controlled in open loop mode. To circumvent the problem we propose a slight perturbation to the frequency in order to regularize the steps for high frequencies. The approach consists in using several heuristic methods such as Practical Swarm Optimization (PSO), Genetic Algorithms (GA) and Ant Colony Optimization (ACO) to obtain the optimal switching instances which define the change in the supply state (polarization). The numerical simulations performed on a stepper model show that regularization of the motor steps can be achieved for a large range of power supply frequencies ranging from quasiperiodic behavior to chaotic behavior

Germination responses of a Saharan species Henophyton deserti Coss. & Durieu to temperature and water stress

Henophyton deserti Coss. & Durieu, is an endemic Saharan plant of the Brassicaceae family. Experiments were conducted to assess the effects of temperature and water stress on seed germination. The germination responses of the seeds of H. deserti in complete darkness were determined over a wide range of temperatures (10°C, 15°C, 20°C, 25°C, 30°C, 35°C) and different water potentials (−0.2, −0.6, −0.8, −1.0, −1.2, −1.4, −1.6, −2.0 MPa) induced by polyethylene glycol (PEG-6000) in order to verify their resistance to drought conditions. Germination was inhibited by either an increase or decrease in temperature from the optimal temperature (20°C) and decreased with a decrease in water potential at all temperatures. An interaction between water potential and temperature yielded no germination at −2 MPa. An understanding of these factors is crucial for successful regeneration and recruitment of these long lived Saharan plant species