702 research outputs found

    Dynamic behaviour of an asymmetric building: Experimental and numerical studies

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    AbstractThe paper presents a study on the seismic assessment of a 21-story building having an asymmetrical plan. The study applies the approach using in-situ measurements to assess the building's seismic performance. According to preliminary observations on site, the soil may have a significant influence on the building's behaviour. That is why it is important to isolate the behaviour of the building from the soil effect (fixed-base structure). First, in-situ dynamic measurements are conducted to identify dynamic characteristics of the building. The Frequency Domain Decomposition (FDD) method is used to determine the vibration modes of the building in three dimensions (3D). First three vibration modes with close frequencies and unusual mode shapes were identified, which shows the relevance of the used method in the case of buildings having complex behaviour. Second, the relevance of the applied approach was checked by using 3D Finite Element (FE) modelling, in both cases: fixed-base structure and soil + structure system

    A Shared \u3cem\u3eCis\u3c/em\u3e-Regulatory Module Activates Transcription in the Suspensor of Plant Embryos

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    The mechanisms controlling the transcription of gene sets in specific regions of a plant embryo shortly after fertilization remain unknown. Previously, we showed that G564 mRNA, encoding a protein of unknown function, accumulates to high levels in the giant suspensor of both Scarlet Runner Bean (SRB) and Common Bean embryos, and a cis-regulatory module containing three unique DNA sequences, designated as the 10-bp, Region 2, and Fifth motifs, is required for G564 suspensor-specific transcription [Henry KF, et al. (2015) Plant Mol Biol 88:207–217; Kawashima T, et al. (2009) Proc Natl Acad Sci USA 106:3627–3632]. We tested the hypothesis that these motifs are also required for transcription of the SRB GA 20-oxidase gene, which encodes a gibberellic acid hormone biosynthesis enzyme and is coexpressed with G564 at a high level in giant bean suspensors. We used deletion and gain-of-function experiments in transgenic tobacco embryos to show that two GA 20-oxidase DNA regions are required for suspensor-specific transcription, one in the 5′ UTR (+119 to +205) and another in the 5′ upstream region (−341 to −316). Mutagenesis of sequences in these two regions determined that the cis-regulatory motifs required for G564 suspensor transcription are also required for GA 20-oxidase transcription within the suspensor, although the motif arrangement differs. Our results demonstrate the flexibility of motif positioning within a cis-regulatory module that activates gene transcription within giant bean suspensors and suggest that G564 and GA 20-oxidase comprise part of a suspensor gene regulatory network

    Modélisation numérique de structures en pisé : analyses et recommandations

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    International audienceL'utilisation du pisé dans la construction s'avère aujourd'hui intéressante dans la nécessaire démarche de bâtir durable. Ce matériau, non transformé industriellement, est porteur d'une énergie grise proche de zéro. De plus, les constructions en pisé apportent un bon confort d'habitation grâce au comportement hygrothermique naturel des murs en terre. Ces remarques participent à un regain d'intérêt pour ce matériau comme le montrent les récentes recherches sur le sujet. Pourtant, des verrous scientifiques persistent dans ce domaine. Peu d'études concernent, en particulier, l'évaluation des performances mécaniques sous sollicitations dynamiques. Cet article présente, dans un premier temps, une revue d'études existantes. Dans un deuxième temps, des simulations numériques ont été menées à l'aide du code d'éléments finis (ASTER). La loi de comportement Drucker-Pager avec écrouissage a été retenue pour les simulations. La pertinence de ce modèle et les paramètres prépondérants ont également été mis en avant par comparaison avec des données expérimentales issues de la littérature

    Aircraft measurements of microphysical properties of subvisible cirrus in the tropical tropopause layer

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    International audienceSubvisible cirrus (SVC) clouds are often observed within the tropical tropopause layer (TTL). Some studies suggest that SVC has a significant impact on the earth radiation budget. The Costa Rica Aura Validation Experiment (CR-AVE) sponsored by the National Aeronautics and Space Administration (NASA) took place near San Jose, Costa Rica from 14 January?15 February 2006. The NASA WB-57F sampled SVC in the TTL from ?75°C to ?90°C with an improved set of cloud particle probes. The first digital images of ice particles in the TTL are compared with replicator images of ice particles collected in 1973 by a WB-57F in the TTL. The newer measurements reveal larger particles, on the order of 100 ?m compared with <50 ?m from the earlier measurements, and also different particle shapes. The 1973 particles were mainly columnar and trigonal, whereas the newer measurements are quasi-spherical and hexagonal plates. The WB-57F also measured very high water vapor contents with some instruments, up to 4 ppmv, and aerosols with mixed organics and sulfates. It is unknown whether these ambient conditions were present in the 1973 studies, and whether such conditions have an influence on particle shape and the development of the large particles. A companion paper (Jensen et al., 2008) presents crystal growth calculations that suggest that the high water vapor measurements are required to grow ice particles to the observed sizes of 100 ?m and larger

    Dielectric, Switching and System Requirements under Out-of-Phase Conditions, during Synchronisation and under Comparable Stresses

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    Recent developments in electrical networks can increase the probability of out-of-phase switching and dielectric stresses being applied to open circuit-breakers, due to asynchronous systems at both sides. This report presents a systematic study of TRV-stresses associated with generator separation and system separation. TRV peak values are higher than required in the Standards, even for relatively small out-of-phase angles (75º to 90º), and the dielectric stresses are high with respect to the shortduration power frequency withstand voltages across a circuit-breaker open contacts, especially taking into consideration the external insulation under pollution and ageing processes. To the opinion of the authors, the Standards should be revised to give users clear and adequate guidance on the assessment and specification of TRV-values and dielectric withstand requirements under out-of-phase conditions

    Methane emission factors from vietnamese rice production: Pooling data of 36 field sites for meta-analysis

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    Rice production is a significant source of greenhouse gas (GHG) emissions in the national budget of many Asian countries, but the extent of emissions varies strongly across agro-environmental zones. It is important to understand these differences in order to improve the national GHG inventory and effectively target mitigation options. This study presents a meta-analysis of CH4 database emission factors (EFs) from 36 field sites across the rice growing areas of Vietnam and covering 73 cropping seasons. The EFs were developed from field measurements using the closed chamber technique. The analysis for calculating baseline EFs in North, Central and South Vietnam in line with the Intergovernmental Panel on Climate Change (IPCC) Tier 2 methodology was specified for the three cropping seasons being early-(E), mid-(M) and late-year (L) seasons. Calculated average CH4_{4} EFs are given in kg ha1^{-1} d1^{-1} and reflect the distinct seasons in North (E: 2.21; L: 3.89), Central (E: 2.84; M+L: 3.13) and South Vietnam (E: 1.72; M: 2.80; L: 3.58). Derived from the available data of the edapho-hydrological zones of the Mekong River Delta, season-based EFs are more useful than zone-based EFs. In totality, these average EFs indicate an enormous variability of GHG emissions in Vietnamese rice production and represent much higher values than the IPCC default. Seasonal EFs from Vietnam exceeded IPCC defaults given for Southeast Asia corresponding to 160% (E), 240% (M) and 290% (L) of the medium value, respectively

    Preparation and Foliar Application of Oligochitosan - Nanosilica on the Enhancement of Soybean Seed Yield

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    Oligochitosan with weight average molecu-lar weight (Mw) of 5000 g/mol was prepared by gamma Co-60 radiation degradation of 4% chitosan solution containing 0.5% H2O2 at 21 kGy. Nanosilica with size of 10 – 30 nm was synthesized by calcination of acid treated rice husk at 700o C for 2 h. The mixture of 2% oligo-chitosan-2% nanosilica was prepared by dispersion of nanosilica in oligochitosan solution. Oligochitosan, nanosilica and their mixture were characterized by gel permeation chromatography (GPC), transmission electr-on microscopy (TEM), X-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), Ultraviolet-visible spectroscopy (UV-Vis), and Furrier transform infrared spectroscopy (FT-IR). Effect of foliar application of oli-gochitosan and oligochitosan-nanosilica on soybean seed yield was conducted in experimental field. Results indi-cated that soybean seed yield increased 10.5 and 17.0% for oligochitosan and oligochitosan-nanosilica, respect-tively for the control. Radiation degraded oligo-chitosan and its mixture with nanosilica can be potentially used for cultivation of soybean with enhanced seed yield
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