Efficient OpenCL-based concurrent tasks offloading on accelerators

Current heterogeneous platforms with CPUs and accelerators have the ability to launch several independent tasks simultaneously, in order to exploit concurrency among them. These tasks typically consist of data transfer commands and kernel computation commands. In this paper we develop a runtime approach to optimize the concurrency between data transfers and kernel computation commands in a multithreaded scenario where each CPU thread offloads tasks to the accelerator. It deploys a heuristic based on a temporal execution model for concurrent tasks. It is able to establish a near-optimal task execution order that significantly reduces the total execution time, including data transfers. Our approach has been evaluated employing five different benchmarks composed of dominant kernel and dominant transfer real tasks. In these experiments our heuristic achieves speedups up to 1.5x in AMD R9 and NVIDIA K20c accelerators and 1.3x in an Intel Xeon Phi (KNC) device.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Control and Model-Aided Inertial Navigation of a Nonholonomic Vehicle

International audienceThe present work deals with the control and localization problem of wheeled-mobile robots with nonholonomic constraints. In the proposed method a simple nonlinear control law, composed of a position and heading direction controller, is designed to asymptotically stabilize the position error. The control law takes into account the constraints on the control signals in order to avoid saturation of the actuators. Furthermore, this paper considers a method of using the dynamic vehicle model and vehicle's nonholonomic constraints in order to aid position and attitude estimates provided by an Inertial Navigation System (INS). It is shown that dynamic model and vehicle's nonholonomic constraints can reduce the error growth in robot position estimates. Simulations are included to confirm the effectiveness of the proposed scheme

Position Control of a Quadrotor under External Constant Disturbance

International audienceIn the present work, an adaptive backstepping algorithm is developed in order to counteract the effects of disturbances. These disturbances are modeled as a constant force in the translational model part and as a constant torque in the orientation model part. We make the deduction of the mathematical expression for the proposed control algorithm and also we show its performance in simulation. Additionally, we include some experiments for validating the results obtained via simulation

Integral backstepping control for trajectory tracking of a hybrid vehicle

International audienceThis article is focused on the trajectory tracking using a hybrid terrestrial aerial vehicle. An integral back-stepping control is proposed for the UAV vehicle mode. In addition, a nested saturation control is developed and applied to regulate the position of the cart vehicle. These control laws are validated by simulations and some experimental results on position control was performed by applying the techniques aforementioned. I. SYSTEM DESCRIPTION In this work control laws are developed for trajectory tracking of a hybrid terrestrial aerial vehicle. These kinds of vehicles have the advantage to be used as a flying vehicle or as a cart depending on the situation. Some situations may be when the vehicle find an obstacle and it has to take the more convenient mode of operation to overcome or to avoid the obstacle. Controlling these hybrid vehicles becomes a challenge. It is necessary to design and implement control laws for the trajectory following in the air and over the floor. The control strategy has to generate a smooth transition when the drone is passing from air to floor or vice versa. There are several works dedicated to path following with hexarotors and also for carts, see for example [1]–[3]. This work considers a particular hybrid vehicle : a mini-UAV that is converted in a cart by attaching to it two wheels without any additional motors as in Fig. 1. The orientation and position of the cart will be controlled by the yaw and pitch angles and by the thrust generated by its helices. Among its characteristics, the thrust direction can be inversed as a result of the pitch angle variation. Therefore, the cart-drone can move forward or backward depending on the sign of pitch angle. This hybrid vehicle in terrestrial mode can turn around z axis. It is also a nonholonomic system because it is not capable to move on the wheels axis direction in terrestrial mode. For more references in cart control refer to [4]–[6]

Precipitation Process in Fe-Ni-Al-based Alloys

This chapter covers first the precipitation and coarsening processes in Fe-Ni-Al alloys aged artificially at high temperatures, as well as their effect on the mechanical properties. These results show the precipitation evolution, morphology of precipitates, coarsening kinetics and mechanical properties such as hardness. Additionally, the effect of alloying elements such as copper and chromium is also studied on the precipitation and coarsening processes. The main results of this section are concerning on the coarsening kinetics and its effect on hardness. Besides, the diffusion couple method is employed to study the precipitation and coarsening process in different Fe-Ni-Al alloy compositions, as well as its effect on the hardness. All the above aspects of precipitation and coarsening are also supported with Thermo-Calc calculations

Velocity control of mini-UAV using a helmet system

International audienceThe usage of a helmet to command a mini-unmanned aerial vehicle (mini-UAV), is a telepresence system that connects the operator to the vehicle. This paper proposes a system which remotely allows the connection of a pilot's head motion and the 3D movements of a mini-UAVs. Two velocity control algorithms have been tested in order to manipulate the system. Results demonstrate that these movements can be used as reference inputs of the controller of the mini-UAV

Nonlinear control of a nano-hexacopter carrying a manipulator arm

International audienceThis paper proposes a simple solution for stabilization of a nano-hexacopter carrying a manipulator arm in order to increase the type of missions achievable by these types of systems. The manipulator arm is attached to the lower part of the hexacopter. The motion of the arm induces a change of the center of mass of the whole body, which induces torques which can produce the loss of stability. The present work deals with the stabilization of the whole system-that is hexacopter and arm-by means of a set of nonlinear control laws. First, an attitude control, stabilizes the hexacopter to a desired attitude taking into account the movement of the arm. Then, a suitable virtual control and the translational dynamics allow the formulation of a nonlinear controller, which drives the aerial vehicle to a desired position. Both controls consist in saturation functions. Experimental results validate the proposed control strategy and compares the results when the motion of the arm is taken into account or not

Genetic inhibition of flowering differs between juvenile and adult Citrus trees

[EN] Background and Aims In woody species, the juvenile period maintains the axillary meristems in a vegetative stage, unable to flower, for several years. However, in adult trees, some 1-year-old meristems flower whereas others remain vegetative to ensure a polycarpic growth habit. Both types of trees, therefore, have non-flowering meristems, and we hypothesize that the molecular mechanism regulating flower inhibition in juvenile trees is different from that in adult trees. Methods In adult Citrus trees, the main endogenous factor inhibiting flower induction is the growing fruit. Thus, we studied the expression of the main flowering time, identity and patterning genes of trees with heavy fruit load (not-flowering adult trees) compared to that of 6-month-old trees (not-flowering juvenile trees). Adult trees without fruits (flowering trees) were used as a control. Second, we studied the expression of the same genes in the meristems of 6-month, and 1-, 3-, 5-and 7-year-old juvenile trees compared to 10-year-old flowering trees. Key Results The axillary meristems of juvenile trees are unable to transcribe flowering time and patterning genes during the period of induction, although they are able to transcribe the FLOWERING LOCUS T citrus orthologue (CiFT2) in leaves. By contrast, meristems of not-flowering adult trees are able to transcribe the flowering network genes but fail to achieve the transcription threshold required to flower, due to CiFT2 repression by the fruit. Juvenile meristems progressively achieve gene expression, with age-dependent differences from 6 months to 7 years, FD-like and CsLFY being the last genes to be expressed. Conclusions During the juvenile period the mechanism inhibiting flowering is determined in the immature bud, so that it progressively acquires flowering ability at the gene expression level of the flowering time programme, whereas in the adult tree it is determined in the leaf, where repression of CiFT2 gene expression occurs.We thank Cristina Ferrandiz (IBMCP-UPV, Spain) and Fernando Andres (UMR AGAP, France) for useful comments on the manuscript. We thank D. Westall for her help in editing the manuscript. This work was supported by a grant from the Ministerio de Economia y Competitividad, Spain (RTA2013-0024-C02-02)Muñoz Fambuena, N.; Nicolas-Almansa, M.; Martinez Fuentes, A.; Reig Valor, C.; Iglesias, DJ.; Primo-Millo, E.; Mesejo Conejos, C.... (2019). Genetic inhibition of flowering differs between juvenile and adult Citrus trees. Annals of Botany. 123(3):483-490. https://doi.org/10.1093/aob/mcy179S4834901233Abe, M. (2005). FD, a bZIP Protein Mediating Signals from the Floral Pathway Integrator FT at the Shoot Apex. Science, 309(5737), 1052-1056. doi:10.1126/science.1115983Albani, M. C., & Coupland, G. (2010). Comparative Analysis of Flowering in Annual and Perennial Plants. Plant Development, 323-348. doi:10.1016/s0070-2153(10)91011-9Andrés, F., & Coupland, G. (2012). The genetic basis of flowering responses to seasonal cues. Nature Reviews Genetics, 13(9), 627-639. doi:10.1038/nrg3291Balanzà, V., Martínez-Fernández, I., Sato, S., Yanofsky, M. F., Kaufmann, K., Angenent, G. C., … Ferrándiz, C. (2018). Genetic control of meristem arrest and life span in Arabidopsis by a FRUITFULL-APETALA2 pathway. Nature Communications, 9(1). doi:10.1038/s41467-018-03067-5Bäurle, I., & Dean, C. (2006). The Timing of Developmental Transitions in Plants. Cell, 125(4), 655-664. doi:10.1016/j.cell.2006.05.005Betancourt, M., Sistachs, V., Martínez-Fuentes, A., Mesejo, C., Reig, C., & Agustí, M. (2014). Influence of harvest date on fruit yield and return bloom in ‘Marsh’ grapefruit trees (Citrus paradisiMacf.) grown under a tropical climate. The Journal of Horticultural Science and Biotechnology, 89(4), 435-440. doi:10.1080/14620316.2014.11513103Blázquez, M. A., Ferrándiz, C., Madueño, F., & Parcy, F. (2006). How Floral Meristems are Built. Plant Molecular Biology, 60(6), 855-870. doi:10.1007/s11103-006-0013-zBlümel, M., Dally, N., & Jung, C. (2015). Flowering time regulation in crops — what did we learn from Arabidopsis? Current Opinion in Biotechnology, 32, 121-129. doi:10.1016/j.copbio.2014.11.023Castillo, M.-C., Forment, J., Gadea, J., Carrasco, J. L., Juarez, J., Navarro, L., & Ancillo, G. (2013). Identification of transcription factors potentially involved in the juvenile to adult phase transition in Citrus. Annals of Botany, 112(7), 1371-1381. doi:10.1093/aob/mct211Chica, E. J., & Albrigo, L. G. (2013). Expression of Flower Promoting Genes in Sweet Orange during Floral Inductive Water Deficits. Journal of the American Society for Horticultural Science, 138(2), 88-94. doi:10.21273/jashs.138.2.88Endo, T., Shimada, T., Fujii, H., Kobayashi, Y., Araki, T., & Omura, M. (2005). Ectopic Expression of an FT Homolog from Citrus Confers an Early Flowering Phenotype on Trifoliate Orange (Poncirus trifoliata L. Raf.). Transgenic Research, 14(5), 703-712. doi:10.1007/s11248-005-6632-3Haberman, A., Ackerman, M., Crane, O., Kelner, J.-J., Costes, E., & Samach, A. (2016). Different flowering response to various fruit loads in apple cultivars correlates with degree of transcript reaccumulation of a TFL1-encoding gene. The Plant Journal, 87(2), 161-173. doi:10.1111/tpj.13190Hanano, S., & Goto, K. (2011). Arabidopsis TERMINAL FLOWER1 Is Involved in the Regulation of Flowering Time and Inflorescence Development through Transcriptional Repression. The Plant Cell, 23(9), 3172-3184. doi:10.1105/tpc.111.088641Mafra, V., Kubo, K. S., Alves-Ferreira, M., Ribeiro-Alves, M., Stuart, R. M., Boava, L. P., … Machado, M. A. (2012). Reference Genes for Accurate Transcript Normalization in Citrus Genotypes under Different Experimental Conditions. PLoS ONE, 7(2), e31263. doi:10.1371/journal.pone.0031263Martínez-Fuentes, A., Mesejo, C., Reig, C., & Agustí, M. (2010). Timing of the inhibitory effect of fruit on return bloom of ‘Valencia’ sweet orange (Citrus sinensis (L.) Osbeck). Journal of the Science of Food and Agriculture, 90(11), 1936-1943. doi:10.1002/jsfa.4038Michaels, S. D., & Amasino, R. M. (1999). FLOWERING LOCUS C Encodes a Novel MADS Domain Protein That Acts as a Repressor of Flowering. The Plant Cell, 11(5), 949-956. doi:10.1105/tpc.11.5.949Muñoz-Fambuena, N., Mesejo, C., Carmen González-Mas, M., Primo-Millo, E., Agustí, M., & Iglesias, D. J. (2011). Fruit regulates seasonal expression of flowering genes in alternate-bearing ‘Moncada’ mandarin. Annals of Botany, 108(3), 511-519. doi:10.1093/aob/mcr164Muñoz-Fambuena, N., Mesejo, C., González-Mas, M. C., Primo-Millo, E., Agustí, M., & Iglesias, D. J. (2012). Fruit load modulates flowering-related gene expression in buds of alternate-bearing ‘Moncada’ mandarin. Annals of Botany, 110(6), 1109-1118. doi:10.1093/aob/mcs190Nishikawa, F., Endo, T., Shimada, T., Fujii, H., Shimizu, T., Omura, M., & Ikoma, Y. (2007). Increased CiFT abundance in the stem correlates with floral induction by low temperature in Satsuma mandarin (Citrus unshiu Marc.). Journal of Experimental Botany, 58(14), 3915-3927. doi:10.1093/jxb/erm246Peña, L., Martín-Trillo, M., Juárez, J., Pina, J. A., Navarro, L., & Martínez-Zapater, J. M. (2001). Constitutive expression of Arabidopsis LEAFY or APETALA1 genes in citrus reduces their generation time. Nature Biotechnology, 19(3), 263-267. doi:10.1038/85719Pillitteri, L. J., Lovatt, C. J., & Walling, L. L. (2004). Isolation and Characterization of a TERMINAL FLOWER Homolog and Its Correlation with Juvenility in Citrus. Plant Physiology, 135(3), 1540-1551. doi:10.1104/pp.103.036178Seo, E., Lee, H., Jeon, J., Park, H., Kim, J., Noh, Y.-S., & Lee, I. (2009). Crosstalk between Cold Response and Flowering in Arabidopsis Is Mediated through the Flowering-Time Gene SOC1 and Its Upstream Negative Regulator FLC. The Plant Cell, 21(10), 3185-3197. doi:10.1105/tpc.108.063883Sgamma, T., Jackson, A., Muleo, R., Thomas, B., & Massiah, A. (2014). TEMPRANILLO is a regulator of juvenility in plants. Scientific Reports, 4(1). doi:10.1038/srep03704Shalom, L., Samuels, S., Zur, N., Shlizerman, L., Zemach, H., Weissberg, M., … Sadka, A. (2012). Alternate Bearing in Citrus: Changes in the Expression of Flowering Control Genes and in Global Gene Expression in ON- versus OFF-Crop Trees. PLoS ONE, 7(10), e46930. doi:10.1371/journal.pone.0046930Shalom, L., Samuels, S., Zur, N., Shlizerman, L., Doron-Faigenboim, A., Blumwald, E., & Sadka, A. (2014). Fruit load induces changes in global gene expression and in abscisic acid (ABA) and indole acetic acid (IAA) homeostasis in citrus buds. Journal of Experimental Botany, 65(12), 3029-3044. doi:10.1093/jxb/eru148Sohn, E. J., Rojas-Pierce, M., Pan, S., Carter, C., Serrano-Mislata, A., Madueno, F., … Raikhel, N. V. (2007). The shoot meristem identity gene TFL1 is involved in flower development and trafficking to the protein storage vacuole. Proceedings of the National Academy of Sciences, 104(47), 18801-18806. doi:10.1073/pnas.0708236104Spiegel-Roy, P., & Goldschmidt, E. E. (1996). The Biology of Citrus. doi:10.1017/cbo9780511600548Sussmilch, F. C., Berbel, A., Hecht, V., Vander Schoor, J. K., Ferrándiz, C., Madueño, F., & Weller, J. L. (2015). Pea VEGETATIVE2 Is an FD Homolog That Is Essential for Flowering and Compound Inflorescence Development. The Plant Cell, 27(4), 1046-1060. doi:10.1105/tpc.115.136150Tan, F.-C., & Swain, S. M. (2007). Functional characterization of AP3, SOC1 and WUS homologues from citrus (Citrus sinensis). Physiologia Plantarum, 131(3), 481-495. doi:10.1111/j.1399-3054.2007.00971.xLeal Valentim, F., Mourik, S. van, Posé, D., Kim, M. C., Schmid, M., van Ham, R. C. H. J., … van Dijk, A. D. J. (2015). A Quantitative and Dynamic Model of the Arabidopsis Flowering Time Gene Regulatory Network. PLOS ONE, 10(2), e0116973. doi:10.1371/journal.pone.0116973Wang, J.-W., Czech, B., & Weigel, D. (2009). miR156-Regulated SPL Transcription Factors Define an Endogenous Flowering Pathway in Arabidopsis thaliana. Cell, 138(4), 738-749. doi:10.1016/j.cell.2009.06.014Weigel, D. (1995). The Genetics of Flower Development: From Floral Induction to Ovule Morphogenesis. Annual Review of Genetics, 29(1), 19-39. doi:10.1146/annurev.ge.29.120195.00031

Links Between Fluctuations in Sockeye Salmon Abundance and Riparian Forest Productivity Identified by Remote Sensing

Pacific salmon (Oncorhynchus spp.) carcasses can fertilize riparian forests with marine-derived nutrients when populations make their annual return to natal streams to spawn; however, the strength of this cross-system linkage likely varies substantially among years due to the interannual fluctuations in abundance that characterize most salmon populations. Here, we used a 36-yr time series (1984–2019) of satellite imagery and salmon abundance estimates to assess spatiotemporal associations between forest greenness (a measure of plant productivity) and adult sockeye salmon (Oncorhynchus nerka) abundance in the lower Adams River, British Columbia, Canada. The Adams River sockeye population displays a quadrennial pattern of abundance, with a dominant cohort that spawns every four years in numbers that are typically two to three orders of magnitude larger than non-dominant cohorts. We found that variation in forest greenness was consistently explained best by models including dominant cohort year, whereas models lacking an index of salmon abundance were the lowest-ranked. Greenness of riparian vegetation increased by an average of 0.015 NDVI units (approximately 1%) in the summer after a dominant cohort return, and this effect on greenness persisted into the subsequent fall (11–13 months after spawning). The positive association between quadrennial pulses of salmon and riparian greenness occurred in plots both within 30 m of the stream and 95–125 m away from the stream, indicating that the spatial extent of fertilization may occur well beyond areas directly adjacent to the riverbank. These results suggest that forests respond to cyclical variation in salmon abundance and that overwinter storage of marine-derived nutrients within catchments allows plants to capitalize on these nutrients in the following growing season. Continued advances in remote sensing technology will enhance our understanding of cross-system resource linkages and can inform the ecosystem-based management of Pacific salmon