Marine algal species and their distribution in Phu Quoc marine protected area

This article presents the raw data in relation to the status of, and the distribution of, the 41 marine algal species occurring around and within the An Thoi coral reef strictly protected zone, Phu Quoc Marine Protected Area. The data, which were collected in May 2017, include the detailed description of the locations, the oceanographical conditions, and the photographs of the 41 marine algal species. For more insight, please see “Marine algal species and marine protected area management: A case study in Phu Quoc, Kien Giang, Vietnam” Huynh and Nguyen, 2019

A weighted residual relationship for the contact problem with Coulomb friction

International audienceIn this work, a weighted residual relationship is proposed as an extension of the standard virtual work principle to deal with the large deformation contact problem with Coulomb friction. This weak form is a mixed relationship involving the displacements and the multipliers defined on the reference contact surface of the contactor and is shown to be equivalent to the strong form of the initial/boundary value contact problem. The discretization in space by means of the finite element method is carried out on the mixed relationship in a simple way in order to obtain the semi-discrete equation system. The contact tangent stiffness is derived and numerical examples are presented to assess the efficiency of the formulation. (c) 2009 Elsevier Ltd. All rights reserved

Outage and bit error probability analysis in energy harvesting wireless cooperative networks

This study focuses on a wireless powered cooperative communication network (WPCCN), which includes a hybrid access point (HAP), a source and a relay. The considered source and relay are installed without embedded energy supply (EES), thus are dependent on energy harvested from signals from the HAP to power their cooperative information transmission (IT). Taking inspiration from this, the author group investigates into a harvest-then-cooperate (HTC) protocol, whereas the source and the relay first harvest the energy from the AP in a downlink (DL) and then collaboratively work in uplink (UL) for IT of the source. For careful evaluation of the system performance, derivations of the approximate closed-form expression of the outage probability (OP) and an average bit error probability ( ABER) for the HTC protocol over Rayleigh fading channels are done. Lastly, the author group performs Monte-Carlo simulations to reassure the numerical results they obtained.Web of Science255746

Ecological Engineering and Restoration of Eroded Muddy Coasts in South East Asia: Knowledge Gaps and Recommendations

Ecological engineering (EE) was employed for developing strategies for stabilizing eroded muddy coasts (EMCs). However, there was a limited analysis of these EE strategies with respect to design, performance, and lessons learned. This study employed a critical review for addressing the limitations. There were four EE models designed with different restoration interventions for stabilizing EMCs. The models using active interventions have not been cost-effective in controlling erosion because the interventions failed to achieve their goals or were costly and unnecessary. Of the two passive intervention models, the one with structures constructed from onshore proved to be more cost-effective in terms of construction costs, the survival rate of transplanted seedlings, and levels of sea mud accumulation. Interventions with adequate consideration of the muddy coastal ecological processes and the ecological reasoning for the positioning of these interventions play a crucial role in stabilizing EMCs. A passive restoration model using gradually expanded interventions should be promoted in order to ensure sustainable management of EMCs in the future

A simple weak form for contact problems with Coulomb friction

This paper proposes a weak form for the contact problem with Coulomb friction, written as extension of the standard virtual work principle and involving both the displacements and the multipliers defined on the reference contact surface. The mixed relationship is shown to be equivalent to the strong form of the initial/boundary value contact problem, and it can be discretized by means of the finite element method in a simple way. Typical numerical examples are given to assess the efficiency of the formulation in statics and dynamics

A SIMPLIFIED ASSESSMENT OF THE LOAD BEARING CAPACITY OF SUCTION CAISSON FOR OFFSHORE WIND TURBINES BASED ON FINITE ELEMENT ANALYSIS

Suction caisson is widely used for offshore wind turbine applications. Its loadbearing capacity depends on the bucket geometry and its embedded soil properties. This paper presents a simplified assessment of the loadbearing capacity of suction caisson based on finite element analysis using the Plaxis 2D program. The load-bearing capacity of the suction caisson is determined based on the resulting load-displacement curve via the tangent intersection method. In addition, this study developed an equivalent equation exploring the relationship between the load-bearing capacity of the suction caisson and the surface foundation. The findings in the study showed that the geometry of the suction has a significant influence on its loadbearing capacity. The suction caissons whose aspect ratios are larger resulted in higher loadbearing capacities. Besides, the equivalent equation in this study could be applied to effectively estimate the load-bearing capacity of suction caisson based on its geometry. The finite element program and the soil ground model analyzed in this study was only an assumption. In the future, experimental studies should investigate the loadbearing capacity of a suction caisson related to its geometry and the embedded soil profile using centrifuge models and large-scale models

Kinetic modeling of essential oil hydro-distillation from peels of pomelo (Citrus grandis L.) fruit grown in Southern Vietnam

Thorough understanding of kinetics plays a key role in improving existing industrial processes. In this study, we attempted to model the kinetics of the hydro-distillation process that produces essential oil from peels of pomelo (Citrus grandis L.) fruit, which is a product with high economic value and a wide range of applications. We first determined the optimal water-to-material ratio for attaining maximal oil yield. Then, further experimental attempts were carried out at different distillation rates to generate experimental data to fit three kinetic models, namely first-order kinetics model, instantaneous washing, followed by diffusion model and simultaneous washing and diffusion model. Overall, the three models have well described the experimental kinetic data on hydro-distillation (R2> 90%). Of which, the simultaneous washing and diffusion model attaining the R2 of 99.97% was chosen as the most suitable to describe the kinetics of the extraction process. Estimated parameters also shown that the washing stage occurs more rapidly than the later, diffusion stage. GC-MS results showed that the obtained oil sample was characterized by the dominance of the D-Limonene compound (97.873%)

Application of Fuzzy-ANFIS Controller for Ball on Wheel System

The ball-on-wheel (BoW) is a nonlinear single input-multi output (SIMO) system consisting of a ball located on a wheel. The system’s challenge is to balance ball at the highest point on the wheel. In this paper, we propose a method of applying ANFIS toolbox in imitating a successful controller (in this case, it is PD controller). This process creates a similar fuzzy controller which controls well this system. Therefore, through this research, ANFIS toolbox shows the ability in imitating an expert‘s control law through collecting data of operations