21 research outputs found
Salt Stress Effects on Seed Germination and Seedling Growth of Barley (Hordeum Vulgare L.) Genotypes
Salt tolerance of twelve barley genotypes was investigated at the germination and seedling growth stages. Germination percentage, speed of germination, shoots and roots fresh weight, K and Na concentrations in the shoots and roots were measured. The genotypic responses varied among growth stages. At the germination stage root length and germination percentage were the most discriminating traits between sensitive and tolerant cultivars. At the seedling growth stage, shoots fresh weight, K+, Na+ and K+/Na+ ratio were the discriminating traits. The evaluated genotypes were grouped into three clusters. The genotypes of first cluster were salt tolerant at the germination stage, those of the second and the third clusters were sensitive and tolerant, respectively, at both growth stages. The results indicated that high K concentration and K/Na ratio were the main differentiating traits among clusters
MĂ©thodes statistiques pour la dĂ©termination de la distance d'arrĂȘt des avalanches
From the moment that the avalanche expert tries to consider the avalanche risk, he focusses on the avalanche limits study. The development of models was favoured by the difficulty to cope with the problem. The variety of approaches gives an idea of this difficulty. As a result, physical, dynamical, symbolical and statistical models were developed to support the expert's decision. The statistical approach was developed to obtain runout distance models. In this study, we followed two research tracks. The first one, called spatial approach, determines maximal runout distance models. The second one, namely spatiotemporal approach, tries to define a model to estimate the runout distance and its corresponding return period. The first approach gives, through the use of two statistical methods already developed, maximal runout distance models for an avalanche path sample selected in Haute-Tarentaise (Savoy, France). Then, both methods are compared. The second approach tries to define the probability for an avalanche to reach a point of the profile line for a given return period. To solve this problem, we are led to determine the law of the avalanche number per year and to estimate the distribution fonction of the runout distance of a fully avalanche in the path. The difficulty to use all topographical parameters and to build an avalanche path sample did not allow to obtain an operationnal model. Nevertheless, an interesting theorical framework to link runout distance and return period is given. At the end, the problems to be solved in order to build an avalanche mapping system are discussed. / DĂ©s qu'un expert tente de prendre en compte le risque d'avalanche, son intĂ©rĂȘt se porte avant tout sur l'emprise des avalanches. La variĂ©tĂ© des approches retenues atteste d'ailleurs de cette difficultĂ©. Ainsi, des modĂšles physiques, dynamiques, symboliques et statistiques ont Ă©tĂ© Ă©laborĂ©s pour tenter d'apporter un soutien Ă l'expert. Du point de vue statistique, on cherche Ă fournir des modĂšles pour la caractĂ©risation de la distance d'arrĂȘt des avalanches. Pour rĂ©pondre Ă cet objectif, deux approches ont Ă©tĂ© dĂ©veloppĂ©es dans cette Ă©tude : l'une qualifiĂ©e de "spatiale" parce qu'elle s'attache Ă fournir des modĂšles pour l'estimation de la distance d'arrĂȘt maximale des avalanches, l'autre dĂ©nommĂ©e "spatio-temporelle" car elle tente de dĂ©finir un modĂšle pour l'estimation de la distance d'arrĂȘt des avalanches et de leurs pĂ©riodes de retour. Dans l'approche spatiale, nous avons pu, Ă partir de deux mĂ©thodes dĂ©jĂ existantes, Ă©laborer des modelĂ©s Ă l'aide d'un Ă©chantillon de sites avalancheux de Haute-Tarantaise (Savoie). De plus, nous avons mis au point un protocole pour la comparaison de ces deux mĂ©thodes. Dans l'approche spatio-temporelle, nous avons tentĂ© de dĂ©finir un cadre mĂ©thodologique pour l'estimation de la probabilitĂ© qu'un point d'un site soit atteint par les avalanches sur une pĂ©riode de temps donnĂ©e. La mise en oeuvre de cette mĂ©thodologie nous a conduit Ă l'ajustement de la loi du nombre d'avalanches par annĂ©e et Ă l'estimation de la fonction de rĂ©partition de l'arrĂȘt d'une avalanche sue le site. La difficultĂ© Ă prendre en compte l'ensemble des paramĂštres topographiques et Ă constituer un Ă©chantillon suffisant n'a cependant pas permis d'obtenir un modĂšle complĂštement opĂ©rationnel. NĂ©anmoins, cette voie semble offrir un cadre intĂ©ressant pour la prise en compte des pĂ©riodes de retours des avalanches. La fin du travail est consacrĂ©e Ă une discussion des problĂšmes Ă rĂ©soudre pour construire un systĂšme de cartographie des zones avalancheuses
Association de divers agents de synergie Ă lâacide caprique dans lâextraction des mĂ©taux de transition
Ce travail porte sur l'extraction synergique des trois métaux cuivre(II), cobalt(II) et nickel(II) en milieu sulfate par l'acide caprique en présence de l'oxyde tri-n-octyl phosphine (TOPO) et la méthyl isobutyl cétone (MIBK) dans le chloroforme.
L'Ă©tude du comportement acido-basique de lâacide caprique dans les systĂšmes chloroforme-eau(Na2SO4) et MIBK-eau(Na2SO4) a montrĂ© que : pKA MIBK > pKA chloroforme > pKA dichloromĂ©thane.
L'Ă©tude du comportement acido-basique du mĂ©lange (acide caprique-TOPO) et (acide caprique- MIBK) dans le systĂšme chloroforme-eau(Na2SO4) a mis en Ă©vidence l'interaction entre acide caprique et le TOPO dâune part et acide caprique et MIBK dâautre part.
On absence du TOPO et MIBK, les complexes de cuivre(II), cobalt(II) et nickel(II) extraits dans la phase organique ont pour stĆchiomĂ©tries CuL22HL, CoL22HL, NiL2 et NiL2HL respectivement conformĂ©ment aux Ă©quilibres d'extraction suivants :
logKex = -7,17
logKex = -11,87
logKex = -14,20
logKex =-12,81
A des faibles concentrations de lâagent synergique TOPO et MIBK une synergie positive est observĂ©e. Tandis que, l'augmentation de la concentration de TOPO et MIBK dans la phase organique rĂ©sulte une diminution de l'extraction
MĂ©thodes statistiques pour la dĂ©termination de la distance d'arrĂȘt maximale des avalanches
La crise de lâolĂ©oduc Edjeleh-GabĂšsâŻ: Au cĆur des enjeux de souverainetĂ© du Maghreb (1954-1962)
Alors que les pourparlers franco-libyens (1954-1956) retiennent toute lâattention des pĂ©troliers français, Paris rĂ©flĂ©chit Ă sĂ©curiser lâĂ©vacuation du pĂ©trole du Sahara algĂ©rien. AprĂšs la perte du Fezzan libyen, la France dĂ©cide de construire un olĂ©oduc transportant le pĂ©trole du gisement dâEdjeleh, situĂ© non de loin de la frontiĂšre libyenne, et traversant le territoire tunisien jusquâau port de la Skhira dans le Golfe de Gabes. La Tunisie est un petit producteur de pĂ©trole, cependant nous verrons que dĂšs 1958, les canalisations dâhydrocarbures qui traversent le pays deviennent aussi un vecteur des intĂ©rĂȘts et de la sĂ©curitĂ© des approvisionnements Ă©nergĂ©tiques français et, europĂ©ens. Lâaccord franco-tunisien du 30 juin 1958 est rapidement dĂ©noncĂ© par le FLN algĂ©rien comme une atteinte Ă la solidaritĂ© maghrĂ©bine et un soutien au colonisateur. Certainement lâune des premiĂšres crises diplomatiques rĂ©gionales, lâaffaire du pipeline Edjeleh-Gabes, met en lumiĂšre les enjeux de souverainetĂ© des diplomaties algĂ©rienne, libyenne et tunisienne Ă lâaune des indĂ©pendances.While the French-Libyan discussions (1954-1956) were retaining the attention of French oil companies, Paris was focusing on securing the evacuation of oil from the Algerian Sahara during the Algerian War (1954-1962). After the loss of the Libyan Fezzan in 1955, France decided to build a pipeline to transport oil from Edjeleh, near the Libyan border, through the Tunisian territory to the port of Skhira in the Gulf of Gabes. Tunisia was a small oil producer after the independence in 1956, however this paper highlights that after 1958 pipelines that cross the country became a vector of French and European interests to secure oil supplies. The French-Tunisian agreement of June 1958 was denounced by the Algerian National Liberation Front as an attack on Maghreb solidarity and a support to the colonizer. Certainly one of the first regional diplomatic crises, the case of the pipeline Edjeleh-Gabes, highlights the issue of sovereignty in the agenda of Algerian, Libyan and Tunisian diplomacies in the context of decolonization of North Africa
PAR-DELĂ SON PASSĂ, LE FUTUR DE LâALGĂRIE SERA-T-IL RĂVOLUTIONNAIRE ? MĂ©moire, vĂ©ritĂ© et justice comme enjeux de la sociĂ©tĂ© civile
LâentrĂ©e des citoyennes et des citoyens algĂ©riens, de maniĂšre massive, sur la scĂšne politique depuis quelques mois, ne constitue ni le premier Ă©pisode de son « ouverture », ni une parenthĂšse isolĂ©e de son histoire. Elle sâinscrit plutĂŽt dans la continuitĂ© dâun processus historique de « pacification du champ politique » initiĂ© dĂšs lâindĂ©pendance, en 1962 (Addi, 2017). Bien que les acteurs et actrices du soulĂšvement, ou Hirak, de 2019 se prĂ©sentent comme les successeurs de diffĂ©rentes gĂ©nĂ©rations ayant rĂ©sistĂ© au rĂ©gime autoritaire (post)colonial, ils et elles assument une rupture nette vis-Ă -vis de la culture et de lâimaginaire politique algĂ©rien hĂ©ritĂ©s de son histoire rĂ©cente. En plaçant « lâĂ©thos non-violent » (Silmiya)1au cĆur de lâappel Ă un changement politique, le peuple surmonte le « trauma colonial » (Lazali, 2018) redoublĂ© par celui de la guerre « contre les civils » (Tahon, 1998), pour sâimposer non plus comme objet mais sujet de lâhistoire2. Se revendiquant souverain (en vertu des articles 7 et 8 de la constitution), il place sa lĂ©gitimitĂ© au-dessus de la lĂ©galitĂ©, pour participer Ă la chose publique au moyen de la chute du rĂ©gime, mais non celle de lâĂtat. Aussi, cette mobilisation des citoyens et des citoyennes nâĂ©tait pas seulement inattendue, elle marque lâentrĂ©e dans une nouvelle Ăšre tant elle constitue un renouvellement de lâhorizon du changement social et du langage politique
A Framework for Recognizing Industrial Actions via Joint Angles
This paper proposes a novel framework for recognizing industrial actions, in the perspective of human-robot collaboration. Given a one second long measure of the human's motion, the framework can determine his/her action. The originality lies in the use of joint angles, instead of Cartesian coordinates. This design choice makes the framework sensor agnostic and invariant to affine transformations and to anthropometric differences. On AnDy dataset, we outperform the state of art classifier. Furthermore, we show that our framework is effective with limited training data, that it is subject independent, and that it is compatible with robotic realtime constraints. In terms of methodology, the framework is an original synergy of two antithetical schools of thought: modelbased and data-based algorithms. Indeed, it is the cascade of an inverse kinematics estimator compliant with the International Society of Biomechanics recommendations, followed by a deep learning architecture based on Bidirectional Long Short Term Memory. We believe our work may pave the way to successful and fast action recognition with standard depth cameras, embedded on moving collaborative robots
A Framework for Recognizing Industrial Actions via Joint Angles
This paper proposes a novel framework for recognizing industrial actions, in the perspective of human-robot collaboration. Given a one second long measure of the human's motion, the framework can determine his/her action. The originality lies in the use of joint angles, instead of Cartesian coordinates. This design choice makes the framework sensor agnostic and invariant to affine transformations and to anthropometric differences. On AnDy dataset, we outperform the state of art classifier. Furthermore, we show that our framework is effective with limited training data, that it is subject independent, and that it is compatible with robotic realtime constraints. In terms of methodology, the framework is an original synergy of two antithetical schools of thought: modelbased and data-based algorithms. Indeed, it is the cascade of an inverse kinematics estimator compliant with the International Society of Biomechanics recommendations, followed by a deep learning architecture based on Bidirectional Long Short Term Memory. We believe our work may pave the way to successful and fast action recognition with standard depth cameras, embedded on moving collaborative robots
Sparse Visual-Inertial Measurement Units Placement for Gait Kinematics Assessment
International audienceThis study investigates the possibility of estimating lower-limb joint kinematics and meaningful performance indexes for physiotherapists, during gait on a treadmill based on data collected from a sparse placement of new Visual Inertial Measurement Units (VIMU) and the use of an Extended Kalman Filter (EKF). The proposed EKF takes advantage of the biomechanics of the human body and of the investigated task to reduce sensor inaccuracies. Two state-vector formulations, one based on the use of constant acceleration model and one based on Fourier series, and the tuning of their corresponding parameters were analyzed. The constant acceleration model, due to its inherent inconsistency for human motion, required a cumbersome optimisation process and needed the a-priori knowledge of reference joint trajectories for EKF parameters tuning. On the other hand, the Fourier series formulation could be used without a specific parameters tuning process. In both cases, the average root mean square difference and correlation coefficient between the estimated joint angles and those reconstructed with a reference stereophotogrammetric system was 3.5deg and 0.70, respectively. Moreover, the stride lengths were estimated with a normalized root mean square difference inferior to 2% when using the forward kinematics model receiving as input the estimated joint angles. The popular gait deviation index was also estimated and showed similar results very close to 100, using both the proposed method and the reference stereophotogrammetric system. Such consistency was obtained using only three wireless and affordable VIMU located at the pelvis and both heels and tracked using two affordable RGB cameras. Being further easy-to-use and suitable for applications taking place outside of the laboratory, the proposed method thus represents a good compromise between accurate reference stereophotogrammetric systems and markerless ones for which accuracy is still under debate