Numerical Study of Canopy Flows in Complex Terrain

Canopy flow plays a substantial role in regulating atmosphere-biosphere exchanges of mass and energy. The worldwide FLUXNET has been developed to quantify the net ecosystem exchange of mass and energy through fluid dynamics in and above vegetation canopy using tower-based eddy covariance (EC) technique. However, EC measurements are subject to advection errors in complex terrain, particularly during nights when atmospheric stability is strong. Because EC measurements are one-dimensional (1D), three-dimensional (3D) air movement, CO2 transport, and temperature variation around the instrumented tower are unknown. We employ a Computational Fluid Dynamics (CFD) model to investigate the impact on CO2 transport of 2D and 3D characteristics of canopy flow resulting from interactions between large-scale synoptic flows and local topography, vegetation and thermal conditions. Under neutral conditions, flow distortion over a forested hill is asymmetric, with recirculation on the lee slope. The presence of vegetation and steepening slope intensifies recirculation depth and extension. The recirculation regions are responsible for CO2 build-up behind the hills. The contribution of advection to the CO2 budget is significant and topographic-dependent. Gentle slopes can cause larger advection error than steep slopes. However, the relative importance of advection to CO2 budget is slope-independent. Under calm and stable conditions, canopy flow is thermally stratified: super-stable layers above and in the deep canopy and an unstable layer inbetween. Vertical exchanges of mass, momentum, and energy are limited by the stabilities of these layers. The pattern of two drainage flows are significantly modified by the interaction between thermal stratification and slope, and are better understood with the distribution of vortices, and the sources and sinks of turbulent kinetic energy. The numerical method is applied to the alpine forest at Renon, Italy to investigate how thermo-topographic and synoptic flows interact to govern canopy flow dynamics and CO2 transport. We found that recirculation with high CO2 concentration developed only when local slope wind is enhanced by synoptic wind. There\u27s no recirculation formed as synoptic wind direction is opposite to the local wind direction and CO2 is quite well mixed. No recirculation appears without synoptic condition under which CO2 builds up mainly at downwind locations

Eliminacion de ácidos nafténicos en agua por oxidación con persulfato y mediante el sistema Fenton

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 05-07-2017Esta tesis tiene embargado el acceso al texto completo hasta el 05-01-201

MuscleVAE: Model-Based Controllers of Muscle-Actuated Characters

In this paper, we present a simulation and control framework for generating biomechanically plausible motion for muscle-actuated characters. We incorporate a fatigue dynamics model, the 3CC-r model, into the widely-adopted Hill-type muscle model to simulate the development and recovery of fatigue in muscles, which creates a natural evolution of motion style caused by the accumulation of fatigue from prolonged activities. To address the challenging problem of controlling a musculoskeletal system with high degrees of freedom, we propose a novel muscle-space control strategy based on PD control. Our simulation and control framework facilitates the training of a generative model for muscle-based motion control, which we refer to as MuscleVAE. By leveraging the variational autoencoders (VAEs), MuscleVAE is capable of learning a rich and flexible latent representation of skills from a large unstructured motion dataset, encoding not only motion features but also muscle control and fatigue properties. We demonstrate that the MuscleVAE model can be efficiently trained using a model-based approach, resulting in the production of high-fidelity motions and enabling a variety of downstream tasks

Dynamic response analysis in bolted joint structure with viscoelastic layer and experimental investigations

In this paper, the dynamic response characteristics of a common double shear lap joint structure with viscoelastic layer are investigated. Firstly, an analytical model is established in shear vibration based on phenomenological model. The fourth order Runge-Kutta method is employed to calculate the harmonic response, where the effect of Coulomb friction and excitation levels on system are presented. Secondly, a new nonlinear finite element model for the bolted joint structure with viscoelastic layer is developed. The simulation results show good agreement with the corresponding experimental results. Finally, the proposed harmonic excitation experiments with laser vibrometer in tangential direction are carried out to investigate the nonlinear behaviors of system, as well as the influence of bolt preload and viscoelastic material on dynamic characteristics of the bolted joint beam. The results show that the viscoelastic layer help reduce vibration at certain extent, especially in the high frequency region of vibration, and some peak frequencies of system can be changed through the viscoelastic layer

Genetic Characterization of the Pathogenic Influenza A/Goose/Guangdong/1/96 (H5N1) Virus: Similarity of Its Hemagglutinin Gene to Those of H5N1 Viruses from the 1997 Outbreaks in Hong Kong

AbstractAnalysis of the sequences of all eight RNA segments of the influenza A/Goose/Guangdong/1/96 (H5N1) virus, isolated from a sick goose during an outbreak in Guangdong Province, China, in 1996, revealed that the hemagglutinin (HA) gene of the virus was genetically similar to those of the H5N1 viruses isolated in Hong Kong in 1997. However, the remaining genes showed greater similarity to other avian influenza viruses. Notably, the neuraminidase gene did not have the 19-amino-acid deletion in the stalk region seen in the H5N1 Hong Kong viruses and the NS gene belonged to allele B, while that of the H5N1 Hong Kong viruses belonged to allele A. These data suggest that the H5N1 viruses isolated from the Hong Kong outbreaks derived their HA genes from a virus similar to the A/Goose/Guangdong/1/96 virus or shared a progenitor with this goose pathogen

Two-step persulfate and Fenton oxidation of naphthenic acids in water

WILEY: "This is the peer reviewed version of the following article: Journal of Chemical Technology and Biotechnology 93 (2018): 2262-2270, which has been published in final form at http://doi.org/10.1002/jctb.5569. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."BACKGROUD: In the current study, two-step persulfate and Fenton oxidation has been investigated for the mineralization of naphthenic acids at 80 °C and initial pH ≈ 8. This pH evolves during the persulfate oxidation step towards the optimum for Fenton oxidation (≈ 3). The effects of persulfate and H2O2doses, iron concentration, duration of the persulfate oxidation step and operating temperature have been assessed. RESULTS: The combined treatment allowed up to ≈ 80% mineralization of cyclohexanoic acid using fairly low relative amounts of reagents (20 and 30% of the stoichiometric for persulfate and H2O2, respectively). For mineralization of cyclohexanoic acid, 115 and 87 kJ mol-1were obtained as representative values of the apparent activation energy for the persulfate and Fenton oxidation steps, respectively. The system was also successfully tested with other naphthenic acids, including cyclohexanebutyric acid, 2-naphthoic acid and 1,2,3,4-tetrahydro-2-naphthoic acid. Treatment of the naphthenic acids tested by this system gave rise to easily biodegradable effluents consisting mainly of short-chain organic acids. The biodegradability was confirmed by the BOD5/COD ratio and respirometric tests. CONCLUSION: The results show the potential application of this approach as a promising cost-effective solution for the treatment of naphthenic acids-bearing aqueous wastes. This approach has significant advantage compared with the single thermally-activated persulfate or Fenton oxidation, since it allows a high mineralization at reduced reagent cost upon replacing part of the persulfate by less expensive H2O2.We are grateful to the Chinese Scholarship Council (CSC) for supporting the Ph.D. program of Xiyan Xu (CSC, File No. 201308410047). Spanish MINECO is also gratefully acknowledged for the financial support through the project CTQ2013-41963-

Inferring of Unfamiliar Words in Listening Comprehension of Japanese Language Among an Advanced Class of Chinese Students Learning Japanese: An Experiment Test Operating Working Memory Capacity and Sentence Contextuality

Japanese learners have insufficient vocabulary knowledge and are likely to encounter unknown words in the comprehension of Japanese sentences. Since inferring the meanings of unfamiliar words contributes to the understanding of the whole sentences, it is considered to be an important strategy in listening comprehension. We investigated the inferring process of unknown words among Chinese learners in an advanced Japanese language class. In the experiment, we used learner's working memory capacity and sentence contextuality as factors. The size of the working memory capacity and the position where the unknown word appears in the sentence (first or second sentence) were set as independent variables. The score and the reaction time of the phonological memory test of unknown words and the comprehension test were measured as dependent variables. The results showed that the Japanese learners put the priority on understanding the meaning of the whole sentence rather than on retaining the phonological information of unknown words in the listening comprehension. Moreover, it became clear that the working memory capacity of the learner could affect the retention of the phonological information of unknown words