Lleida, Spain
Lleida, Spain

Time filter

Source Type

Gom Ayats J.R.,Polytechnic University of Catalonia | Diego-Ayala U.,Electronic Variable Technologies SL | Artes F.F.,Polytechnic University of Catalonia | Artes F.F.,Fundacio Center
Journal of Power Sources | Year: 2012

The singular point transition concept relates a novel type of continuously variable transmission. This transmission comprises a pair of planetary gear trains and a couple of electric motors, used to control the overall speed ratio. Its singularity lies in the topology of operation, with less than 10% of nominal power circulating through the electric path. This low power level is achieved by segmenting the range of operation of the transmission. To validate this technology, a test bed was built. The transmission presented here is able to provide any output/input speed ratio within the interval of 0:1.55, meaning that it also offers the function of an infinite variable transmission. Description of the system and results of experimental tests are presented. The results showed that the transmission is able to function in the whole range of operation. They also showed that under load conditions the fraction of power transmitted through the electric path is maintained around the design value. © 2011 Published by Elsevier B.V.


Goma Ayats J.R.,Polytechnic University of Catalonia | Diego-Ayala U.,Electronic Variable Technologies SL | Minguella Canela J.,Polytechnic University of Catalonia | Minguella Canela J.,Fundacio Center | And 3 more authors.
Mechanism and Machine Theory | Year: 2012

This article presents a methodology for the kinematic analysis of complex gear trains comprised of planetary gear trains. It is based on the utilisation of hypergraphs, which provides a novel view into the analysis of this type of power trains. The hypergraphs are used to aid in the understanding of the inter-relation between the various branches of the mechanism and to develop the kinematic equations. The method presented here provides a way to define the kinematic relations existing between all the branches of a mechanism, including branches with a variable speed ratio. The time required to determine the equations for the speeds of different branches can be dramatically reduced if this method is followed. © 2011 Elsevier Ltd. All rights reserved.


Vaquer S.,Institute Municipal Dinvestigacio Medica Of Barcelona Imim | Cuyas E.,Institute Municipal Dinvestigacio Medica Of Barcelona Imim | Rabadan A.,Fundacio Center | Gonzalez A.,Fundacio Center | And 2 more authors.
F1000Research | Year: 2014

Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay ® (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and interesting research lines in biology and human physiology with the potential for significant benefits for both space and terrestrial medicine. © 2014 Vaquer S et al.


Westerman P.R.,University of Rostock | Atanackovic V.,University of Lleida | Royo-Esnal A.,University of Lleida | Torra J.,University of Lleida | Torra J.,Fundacio Center
Arthropod-Plant Interactions | Year: 2012

Weeds persist in rain-fed cereal fields in NE Spain, despite intense herbicide use and high seed removal rates by granivorous harvester ants. Herbicide resistance is involved, but certain weed species also appear to escape seed removal by granivores. To identify the mechanisms involved, we measured seed removal rates (three fields in 2010) and the timing of seed shed (one field in 2009 and three fields in 2010) and used an existing model, which integrates short-term rates of seed shed, burial and removal, to estimate long-term seed removal rates. Averaged over years, fields and weed species, the long-term seed removal rate was estimated at 72 % (range 46-100 %). Fifteen to 25 % of the seeds of Bromusdiandrus avoided removal by being less attractive (low removal rates), and another 0-29 % escaped through crop harvest, which made seeds inaccessible to granivores. Similarly, 20-32 % of the Papaverrhoeas seeds escaped through crop harvest, while another 13-17 % escaped by burial into the soil (small seed size). Other species, such as Galiumspurium or Diplotaxiserucoides, had no means of avoiding seed removal by harvester ants. In particular, the more troublesome weeds, such as B. diandrus, P. rhoeas and L. rigidum, combined herbicide resistance or tolerance with avoidance mechanisms against granivory. © 2012 Springer Science+Business Media B.V.


Garcia A.L.,University of Lleida | Recasens J.,University of Lleida | Forcella F.,U.S. Department of Agriculture | Torra J.,Fundacio Center | Royo-Esnal A.,University of Lleida
Weed Science | Year: 2013

A model that describes the emergence of ripgut brome was developed using a two-season data set from a no-tilled field in northeastern Spain. The relationship between cumulative emergence and hydrothermal time (HTT) was described by a sigmoid growth function (Chapman). HTT was calculated with a set of water potentials and temperatures, iteratively used, to determine the base water potential and base temperature. Emergence of ripgut brome was well described with a Chapman function. The newly-developed function was validated with four sets of data, two of them belonging to a third season in the same field and the other two coming from independent data from Southern Spain. The model also successfully described the emergence in different field management and tillage systems. This model may be useful for predicting ripgut brome emergence in winter cereal fields of semiarid Mediterranean regions. © Weed Science Society of America.


Baino F.,Polytechnic University of Turin | Tallia F.,Imperial College London | Novajra G.,Fundacio Center | Minguella J.,Technology Center | And 2 more authors.
Key Engineering Materials | Year: 2015

Over the last two decades, the philosophy behind an optimal fixation of orthopaedic implants progressively evolved towards "bone-conservative" solutions and, accordingly, the researchers' attention moved from simple mechanical fixation of the prosthesis to host bone by using screws or acrylic cement to new strategies based on a physico-chemical bond (surface modification) in order to minimize bone resection/loss and maximize tissue-implant integration. This research work explores the feasibility of a novel bioceramic single-piece acetabular cup for hip joint prosthesis that can be anchored to the patient's pelvic bone by means of a bone-like trabecular coating (scaffold) able to promote implant osteointegration. © (2015) Trans Tech Publications, Switzerland.

Loading Fundacio Center collaborators
Loading Fundacio Center collaborators