Finite element analysis of non-isothermal multiphase porous media in dynamics

This work presents a mathematical and a numerical model for the analysis of the thermo-hydro-mechanical (THM) behavior of multiphase deformable porous materials in dynamics. The fully coupled governing equations are developed within the Hybrid Mixture Theory. To analyze the THM behavior of soil structures in the low frequency domain, e.g. under earthquake excitation, the u-p-T formulation is advocated by neglecting the relative acceleration of the fluids and their convective terms. The standard Bubnov-Galerkin method is applied to the governing equations for the spatial discretization, whereas the generalized Newmark scheme is used for the time discretization. The final non-linear and coupled system of algebraic equations is solved by the Newton method within the monolithic approach. The formulation and the implemented solution procedure are validated through the comparison with other finite element solutions or analytical solutions

SECONDARY METABOLITES PRODUCED BY MARINE BACTERIRUM MICROMONOSPORA SP. (G068)

Nine compounds (1-9) were isolated and characterized from the culture broth of the marinebacteria Micromonospora sp. (strain G068), which was isolated from sediment collected at CoTo – Quang Ninh. Their structures were determined by spectroscopic analysis including MS, 1DNMR and 2D NMR, as well as by comparison with reported data in the literature. Allcompounds were evaluated for their antimicrobial activities against a panel of clinicallysignificant microorganisms. Compounds 1, 6, and 9 selectively inhibited Escherichia coli withMIC values of 128, 128 and 64 μg/mL, respectively

Three Essays on International Trade and Informal Employment

In this dissertation I use theory, empirics, and calibration with Vietnamese firm-level data which I obtain from the Statistics General Office of Vietnam to examine the effects of international trade and foreign direct investment on the hiring of informal employment. In the first chapter, I study the effects of export opportunities on the share of informal employment across firms in an environment in which tariffs through demand volume and volatility can affect firms\u27 hiring decisions. I demonstrate that the heterogeneity in productivity is a relevant factor in explaining changes in informality share. It is predicted that access to international trade reduces the incidence of informality if the effects of raising output on the demand for formal workers dominate the increased demand for informal workers due to the greater volatility. Using tariff data on the United States-Vietnam Bilateral Trade Agreement together with the Vietnam Enterprise Surveys, I find that greater export opportunities are significantly related to reductions in relative demand for informal employment, and focusing on cross section variation, more productive firms hire a lower share of informal workers. Larger firms respond less to tariff liberalization, so my findings suggest that access to international markets may be the most effective for smaller exporters to reduce informal employment. The second chapter provides firm-level evidence of the relationship between foreign investment and informal employment. I examine the informality differentials between FDI and domestic firms and the informality spillover effect of FDI in the Vietnamese manufacturing sector. The results indicate that FDI firms not only create more jobs but also reduce informality by creating relatively more formal jobs. Foreign multinationals offer higher wages than domestic firms even after controlling for differences in informality share. The prevalence of foreign direct investment generates a negative spillover effect in terms of informality share in domestic firms within an industry, but increases the informality level of domestic firms within a province. In the third chapter, I analyze the effects of trade liberalization and foreign direct investment on labor informality in a dynamic general equilibrium model. I show that escalating import competition increases the size of the informal sector, inducing a reallocation of workers from the formal sector to informal firms. More specifically, the informal sector grows by 1.5\% in response to a 10\% drop in import tariffs. Alternatively, export opportunities diminish the level of informality, suggesting that a 10\% drop in export tariffs reduces the size of the informal sector by 0.1\%. Comparative advantage in wages motivates agents to reallocate labor between the two sectors. Moreover, the FDI analysis shows that a decline in the size of the formal sector is associated with increases in foreign direct investment. Quantitatively, a 10\% increase in FDI reduces informal output and employment by 2\%. This is because foreign firms bring intense competition that drives out both formal and informal domestic firms, creating a smaller informal labor market. The policy implication is that export and FDI liberalization should be employed to improve labor conditions by reducing the level of informality

Trade Liberalization and Development in ICT Sector and its impact on household welfare in Viet Nam

The ICT sector in Viet Nam had not been developed until the 1980s. However, over the last decade of rapid growth, it has had a powerful impact on many aspects of life in this country. Although the ICT sector is still at an early stage of development and lags behind many other countries in the region, the government of Viet Nam made strong commitments to upgrade the nation’s ICT capability and implemented significant reforms in terms of trade and investment liberalization in ICT sector over the last decade.Trade Liberalization, ICT, Household welfare, Viet Nam

X-PDNet: Accurate Joint Plane Instance Segmentation and Monocular Depth Estimation with Cross-Task Distillation and Boundary Correction

Segmentation of planar regions from a single RGB image is a particularly important task in the perception of complex scenes. To utilize both visual and geometric properties in images, recent approaches often formulate the problem as a joint estimation of planar instances and dense depth through feature fusion mechanisms and geometric constraint losses. Despite promising results, these methods do not consider cross-task feature distillation and perform poorly in boundary regions. To overcome these limitations, we propose X-PDNet, a framework for the multitask learning of plane instance segmentation and depth estimation with improvements in the following two aspects. Firstly, we construct the cross-task distillation design which promotes early information sharing between dual-tasks for specific task improvements. Secondly, we highlight the current limitations of using the ground truth boundary to develop boundary regression loss, and propose a novel method that exploits depth information to support precise boundary region segmentation. Finally, we manually annotate more than 3000 images from Stanford 2D-3D-Semantics dataset and make available for evaluation of plane instance segmentation. Through the experiments, our proposed methods prove the advantages, outperforming the baseline with large improvement margins in the quantitative results on the ScanNet and the Stanford 2D-3D-S dataset, demonstrating the effectiveness of our proposals.Comment: Accepted to BMVC 202

Advances in Smart Technologies for Structural Health Monitoring of Cable-stayed Bridges

This study deals with the general problem of developing smart technologies for vibration and impedance-based structural health monitoring (SHM) of cable-stayed bridges. The following approaches are implemented to achieve the objective. Firstly, vibration- and impedance-based SHM methods suitable for cable-stayed bridge are briefly outlined. Secondly, smart sensors are designed for vibration- and impedance-based SHM. Thirdly, the practicality of the smart sensor system is evaluated on a real cable-stayed bridge, Hwamyung Bridge in Korea. The system's performance is experimentally analyzed under various cable forces and weather conditions. Finally, the experimental modal parameters are identified by numerical modal analyses of the target bridge. Also, its structural parameters are estimated from the vibration-based structural identification using experimental modal parameters

Explanations Generation For Web Service Workflow

The motivation for the work is the challenge of providing textual explanations of automatically generated scientific workflows (e.g., paragraphs that scientists can include in their publications). The extended abstract presents a system which generates explanations for a web service workflow from sets of atoms derived from a collection of ontologies. The system, called nlgPhylogeny, demonstrates the feasibility of the task in the Phylotastic project, that aims at providing evolutionary biologists with a platform for automatic generation of phylogenetic trees given some suitable inputs

Hybrid-Trefftz finite elements for elastostatic and elastodynamic problems in porous media

The displacement and stress models of the hybrid-Trefftz finite element formulation are applied to the elastostatic and elastodynamic analysis of two-dimensional saturated and unsaturated porous media problems. The formulation develops from the classical separation of variables in time and space, but it leads to two time integration strategies. The first is applied to periodic problems, which are discretized in time using Fourier analysis. A mixed finite element approach is used in the second strategy for discretization in time of non-periodic/transient problems. These strategies lead to a series of uncoupled problems in the space dimension, which is subsequently discretized using either the displacement or the stress model of the hybrid-Trefftz finite element formulation. The main distinction between the two models is in the way that the interelement continuity is enforced. The displacement model enforces the interelement compatibility, while the stress model enforces the interelement equilibrium. As is typical of Trefftz methods, for both models, the approximation bases are constrained to satisfy locally the homogeneous form of the domain (Navier) equations. The free-field solutions of these equations are derived in cylindrical coordinates and used to construct the domain approximations of the hybrid-Trefftz displacement and stress elements. If the original equations are non-homogeneous, the influence of the source terms is modelled using Trefftz-compliant solutions of the corresponding static problem. For saturated porous media, the finite element models are based on the Biot's theory. It assumes an elastic solid phase fully permeated by a compressible liquid phase obeying the Darcy's law. For the modelling of unsaturated porous media, the finite elements are formulated using the theory of mixtures with interfaces. The model is thermodynamically consistent and considers the full coupling between the solid, fluid and gas phases, including the effects of relative (seepage) accelerations. Small displacements and linear-elastic material behaviour are assumed for all models

Hydrophyte communities in the Tam Giang - Cau Hai lagoon

The Tam Giang - Cau Hai lagoon in Thua Thien-Hue province is the largest lagoon in South East Asia and also one of the places having the largest area of seagrass in Vietnam. The study results from 2009 to 2017 showed that 6 seagrasses species were identified (Halodule uninervis is a newly recorded species, however, Halophila minor is not recorded) and there were 8 freshwater grass species (with the exception of Potamogeton maackianus), with a total area of 2,840 ha. In particular, the area of seagrass has been recovering significantly from 1,000 hectares in 2009 to 2,037 hectares in 2017