VIBRATION OF SANDWICH BEAMS REINFORCED BY CARBON NANOTUBES UNDER A MOVING LOAD

This paper studies vibration of sandwich beams reinforced by carbon nanotubes (CNTs) under a moving point load. The core of the beams is homogeneous while their two faces are of carbon nanotube reinforced composite material. The effective properties of two face sheets are determined by extended rule of mixture. A uniform distribution (UD) and four different types of functionally graded (FG) distributions, namely FG-X, FG-FG-V, FG-O, are considered. Based on a third-order shear deformation theory, a finite element formulation is derived and used to compute the vibration characteristics of the beams.

BRAIN TUMOR SEGMENTATION BASED ON U-NET WITH IMAGE DRIVEN LEVEL SET LOSS

This paper presents an approach for brain tumor segmentation based on deep neural networks. The paper proposes to utilize U-Net as an architecture of the approach to capture the fine and soars information from input images. Especially, to train the network, instead of using commonly used cross-entropy loss, dice loss or both, in this study, we propose to employ a new loss function including Level set loss and Dice loss function. The level set loss is inspired from Mumford-Shah functional for unsupervised task. Meanwhile, the Dice loss function measures the similarity between the predicted mask and desired mask. The proposed approach is then applied to segment brain tumor from MRI images as well as evaluated and compared with other approaches on a dataset of nearly 4000 brain MRI scans. Experiment results show that the proposed approach achieves high performance in terms of Dice coefficient and Intersection over Union (IoU) scores.

LIFE-TIME PREDICTION FOR POLYMER MATERIALS

Polymer testing including natural, accelerated testing or creep and fatigue testing, etc. is very important to evaluate the changes in properties, structure, morphology and durability of polymer materials. This is also the basis for experts to predict life-time or service working life or safe working life of polymer materials. This review presents an overview of the life-time prediction for polymer materials owing to natural tests or accelerated ageing tests and the methods for extrapolation of data from induced thermal degradation.

FULLY TRANSPARENT METAMATERIAL AMC BACKED CPW FED MONOPOLE ANTENNA FOR IOT APPLICATIONS

In this paper, a fully transparent antenna comprising of an Artificial Magnetic Conductor (AMC) backed Co-planar Waveguide (CPW) fed dual-ring monopole is presented. The monopole antenna and AMC structure achieve transparency due to the use of AgHT-8 conductive oxide and Plexiglas substrate. Measured antenna performance shows an impedance bandwidth of 5.3 – 6 GHz (12.4%) in the U-NII-1 to U-NII-4 frequency band with a peak gain of 5.7 dBi which is approximately an increase of 4.5% and 3.9 dBi, respectively, as compared to the standalone antenna. The simulation and the measurement results agree well with each other which proves the validity of the proposed design. To the best of our knowledge, the proposed antenna is the first fully transparent antenna design combining a transparent radiator and a transparent AMC structure.

ADJUSTING THE LOW MOLECULAR WEIGHT OF HYDROXYETHYL CELLULOSE AND APPLIED TO EXTRACT PROTEINS IN NATURAL RUBBER LATEX

Natural rubber latex (NRL) with “low protein content” is regarded as less allergenic latex for medical gloves, medical products, condoms, etc. Therefore, this study was conducted to strengthen the fundamental approach of making “low protein NRL” via oligosaccharide hydroxyl ethyl cellulose (oligoHEC) treatment. OligoHEC (Mw ~10,000 g/mol) is degradation product of HEC (Mw ~90,000 g/mol) by 1.5% H2O2 treatment combined with hydrothermal at temperature for 30 minutes at 121°C, pressurized rate of 0.38 mPa by autoclave equipment. OligoHECs were employed to form electrical bonds with the proteins. The target of this study is protein content of NRL ≤ 50 µg/g of rubber, we surveyed the effect of oligoHEC treatment towards the solution proteins content of NRL. Results show that oligoHEC at low concentration (0.25%) effectively extracted the proteins molecules. Interestingly, allergenic proteins content of NRL serum was decreased proportionally (< 50 µg/g of rubber) with the upsurge of oligoHEC concentration, suggesting deactivation of allergenic. These preliminary results indicate a potential approach to produce low allergenic risk NRL products with adding of oligoHEC

INVESTIGATION ON EFFECT OF SURFACE ROUGHNESS PATTERN TO DYNAMIC PERFORMANCE OF MEMS RESONATORS IN VARIOUS TYPES OF GASES AND GAS RAREFACTION

The average modified molecular gas lubrication (MMGL) equation, which is modified with pressure flow factors and effective viscosity, is utilized to analyze the squeeze film damping (SFD) on micro-beam resonators considering effect of surface roughness pattern in various types of gases and gas rarefaction. Then, effect of surface roughness pattern (film thickness ratio and Peklenik number) is discussed on the quality factor (Q-factor) of micro-beam resonators in various types of gases and gas rarefaction. Thus, effect of surface roughness pattern is significantly reduced as effective viscosity of gas decreases in higher mode of resonator and higher gas rarefaction.

PREPARATION OF FEED-GRADE MONOCALCIUM PHOSPHATE BY CRYSTALLIZATION IN AQUEOUS MEDIUM: CALCULATION AND EXPERIMENTS

In this paper, we present the results of calculation, and experiments for the preparation of feed-grade monocalcium phosphate by crystallization method in phosphoric acid solution. Some parameters influence to the production such as the reaction and crystallization temperature, the ratio of recycle mother liquor to reactant mixture have been investigated. The results show that the crystallization method in the preparation of monocalcium phosphate will give product with higher quality, less impurities that will be suitable for animal feed additives.

BROADBAND POLARIZATION CONVERSION BASED ON SMALL-SIZE METAMATERIAL IN THE GHz BAND

We proposed a small GHz metamaterial perfect absorber, which can operate in two different functional modes depending on the orientation of unit-cell structure. Firstly, when the unit-cell structure is oriented symmetrically to the external electric-field direction, an absorption mode is achieved with a near perfect absorption peak. Secondly, by rotating the resonator structure on top layer, metamaterial is asymmetric to the external field, leading to the excitation of cross-coupling effect.

THE STUDY ON SOME PARAMETERS AFFECTING THE DEGRADATION OF METHYLENE BLUE IN WATER BY ELECTRO-FENTON USING TI/PBO2 ANODE

In this work, the combination of two advanced oxidation processes, electro-Fenton (hydroxyl radical ●OH generated by reactions on cathode) and anodic oxidation (●OH produced directly on anode), in the same reactor was studied to evaluate the treatment of methylene blue (MB) dye in aqueous solutions. This electrochemical system was equipped with a commercial carbon felt cathode (9.5cm 12cm), lead dioxide-coated titanium anode (10 12cm), direct current (DC) and continuously aerated. The effects of operating parameters such as pH, applied current (I), catalyst concentration ([Fe2+]) and MB concentration (C0) on MB removal efficiency were investigated through monitoring MB concentration at different times by spectrophotometric method. An optimal process was achieved at the condition of [Fe2+] = 0.1 mM; pH 3.0; [Na2SO4] = 0.05 M; i = 2.5 mA.cm-2 and after 60 minutes of electrolysis, 92.19% of MB was removed which was far higher than the figure obtained by using individually electro-Fenton (73.77%) or anodic oxidation (58.04%). These experimental results have demonstrated that the combination of electro-Fenton and anodic oxidation using Ti/PbO2 electrode is a prospective method for destruction of persistent dyes.

BIOMASS AND CARBON STOCK ESTIMATION OF COASTAL MANGROVES AT HAI PHONG COAST USING REMOTE SENSING AND FIELD INVESTIGATION- BASED DATA

Estimated results of 17 plots evenly distributed across study sites showed that the amount of tree carbon stocks was significantly lower than in soil, normally ranged from 9.9 ÷ 29.55 (tons ha-1) and in contrast by using the Walkley-Black method, these total soil organic carbon were in the range from 81.76 ÷ 323.83 tons ha-1 (average = 161.47±15.85 tons ha-1), which pointed out strong relationship between tree density and soil organic carbon in the study areas.