Influence of MRE Education on Explosive Ordnance Disposal in Quang Tri

In collaboration with local and international organizations, Project RENEW is facilitating comprehensive mine risk education initiatives in Vietnam’s Quang Tri province

An Efficient Spectral Leakage Filtering for IEEE 802.11af in TV White Space

Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant spectral leakage due to the accumulation of multiple sinc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient spectral leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce spectral leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ISI), resulting in a loss of spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better spectral leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters

Upper bound limit analysis of plates using a rotation-free isogeometric approach

International audienceThis paper presents a simple and effective formulation based on a rotation-free isogeometric approach for the assessment of collapse limit loads of plastic thin plates in bending. The formulation relies on the kinematic (or upper bound) theorem and namely B-splines or non-uniform rational B-splines (NURBS), resulting in both exactly geometric representation and high-order approximations. Only one deflection variable (without rotational degrees of freedom) is used for each control point. This allows us to design the resulting optimization problem with a minimum size that is very useful to solve large-scale plate problems. The optimization formulation of limit analysis is transformed into the form of a second-order cone programming problem so that it can be solved using highly efficient interior-point solvers. Several numerical examples are given to demonstrate reliability and effectiveness of the present method in comparison with other published methods

The mathematical model of the improved system of the seat with adjustable pressure profile

Following a patented solution, a seat which is possible to change its stiffness was created. The seat contains an actively controlled pneumatic spring element (the PSE). For the requirement of working faster and more precisely, an improvement was applied. This article deals with derivation of mathematical model of the improved PSE system used for subsequent analysis. The model is considered as a mixed model which is a combination of single-discipline subsystems as mechanical, electrical, fluid and control ones. The simulations are carried out for varied input parameters and both the system parameters and system characteristics are calculated. The results describe the behavior of the improved system in two modes of controller setup: constant pressure and constant stiffness under static and dynamic condition

Isolation and identification of yeasts from local fruits in Thua Thien Hue province, Vietnam

In this study, a total of 30 yeast isolates were recovered from local fruits in Thua Thien Hue province. Genetic characterization based on the ITS sequences identified isolates belonging to 3 species including Saccharomyces cerevisiae, Lachancea fermentati, and Clavispora fructus, with high sequence homology (over 99%) compared to published sequences in the GenBank. All identified S. cerevisiae isolates could grow well at 30°C and ferment several sugar including fructose, galactose, sucrose, mannose, maltose, and raffinose with different performances, but were inhibited at temperature higher than 35°C. The strains also grew well in the medium containing 5% ethanol (v/v) and 200 g/L glucose, but their growth ability was decreased gradually with an increase in ethanol and glucose concentrations. Interestingly, D14 strain was able to grow in the medium supplemented with 12% of ethanol, and 500 g/L of glucose at 45°C, while D7 strain could utilize both mannitol and glycerol at a low level. Our results also indicated that some strains have relatively high sedimentation efficiency, which are favorable conditions for beer fermentation and biomass recovery. The isolated yeast strains with good tolerance properties may provide a potential source of valuable raw materials for applications in beverage production and food processing

MORPHOLOGICAL AWARENESS OF STUDENTS MAJORING IN ENGLISH STUDIES TOWARDS VOCABULARY LEARNING

For those learning a second language, vocabulary plays a vital role in mastering the new one, and possessing a colossal vocabulary is extremely necessary. The paper aims to look into and assess students' awareness of morphology and the effectiveness of this approach through vocabulary learning. The subjects in this study were juniors majoring in English at a university in the south of Vietnam. The test, questionnaire, and interview were the three instruments used in this study to triangulate the results. A total of 49 students majoring in English Studies took the test, 40 students completed the questionnaire, and four students participated in an interview to evaluate their proficiency and morphological knowledge. The results of the study showed that students' awareness levels were average, and they were knowledgeable enough to employ this strategy for acquiring vocabulary. Additionally, it also enables students to comprehend morphology's benefits and drawbacks during their learning vocabulary process.  Article visualizations

Laboratory Hydro-mechanical Characterisation of Boom Clay at Essen and Mol

International audienceBoom clay has been selected as a potential host rock formation for the geological disposal of radioactive waste in Belgium. In the present work, the hydro-mechanical behaviour of Boom clay samples from the borehole Essen-1 at a depth of 220 - 260 m and from HADES that is the underground rock laboratory at Mol in Belgium, at 223-m depth was investigated in the laboratory by performing low pressure oedometer tests (vertical effective stress ranging from 0.05 to 3.2 MPa), high pressure oedometer tests (vertical effective stress ranging from 0.125 to 32 MPa), isotropic consolidation tests (confining effective stress ranging from the in-situ stress to 20 MPa) and triaxial shear tests. It has been observed that the mineralogy, geotechnical properties and hydro-mechanical behaviour of Boom clay from Essen at 227-m, 240-m and 248-m depths are similar to that of Boom clay from Mol. As in the case of Boom clay at Mol, the failure envelope of Boom clay at Essen in the p'-q plane is not linear. The slope of the portion beyond the pre-consolidation stress of Boom clay from Essen is almost the same as that from Mol, suggesting a similar internal friction angle of about 13°. The compression curves (void index Iv versus logarithm of vertical stress) beyond the pre-consolidation stress are the same for both samples from Mol and Essen, and situated between the intrinsic compression line (ICL) and the sedimentation compression line (SCL). The yield stress determined from oedometer tests seems to be stress-path dependent and lower than the pre-consolidation stress. Thus determining the over-consolidation ratio (OCR) using the yield stress value would lead to an incorrect estimate. From a practical point view, the laboratory test results from Essen and their comparison with those from Mol provide important information regarding the transferability of knowledge on Boom clay at different sites, taking into account the fact that most investigations have been carried out on Boom clay at Mol

Mapping impervious surface change from remote sensing and GIS data: A case study in Hochiminh city, Vietnam

Impervious surface is artificial surfaces that prevent water from entering the soil. The increase in impervious surface area has led to negative impacts on the urban environment, including an increase in the risk of flooding, a decrease in vegetation cover, and the formation of urban heat islands. This paper presents the results of building a predictive model of impervious surfaces in Hochiminh city from remote sensing and GIS data. Landsat and Sentinel 2 satellite images for the period 2002–2022 are used to classify impervious surfaces and extract input layers about vegetation cover, land surface temperature, combined with GIS data (elevation, slope, aspect, distance to road, distance to hydrology, population density) for modeling and predicting impervious surface changes in future. 03 machine learning algorithms, including Support Vector Machine (SVM), Random Forest (RF), Classification and Regression Trees (CART) and maximum likelihood method are used to classify impervious surfaces from Landsat satellite images, then select the method with the highest accuracy. To predict the future distribution of impervious surface, this study uses Cellular Automata (CA) model and 02 artificial intelligence algorithms (Artificial Neural Network - ANN, Logistic Regression - LR). The results obtained in the study can be effectively used for urban planning, minimizing the impact of the process of increasing the impervious surface on the urban environmen