Mott Transition in the Asymmetric Hubbard Model at Half-filling: Equation of Motion Approach

Anh-Tuan Hoang,Thi-Thu-Trang Tran,Duc-Anh Le 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.2

We investigate the Mott metal-insulator transition in the asymmetric Hubbard model, which may describe the ground states of fermionic atoms trapped in optical lattices. We use the dynamical mean-field theory and the equation of motion approach to calculate the density of states at the Fermi level and the double occupation for various values of the on-site interaction U and the hopping asymmetry r. The critical interaction is also obtained as a function of the hopping asymmetry. Our results are in good agreement with the ones obtained by using the dynamical mean field theory with the exact diagonalization and the quantum Monte Carlo techniques.

Focusing ultrasonic waves in a 2-D covered channel above the periodic array of Helmholtz resonators

Anh Hoang Vu,황영인,김학준,송성진 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

This paper presents the numerical simulation and experiments on focusing low-frequency ultrasonic waves in a 2-D covered channel above acoustic metamaterials composed of the periodic array of Helmholtz resonators, in which the refractive index can be in a negative value. The 2-D channel above the acoustic metamaterials is covered by a plate to limit the area affected by the negative refractive index metamaterials. Ultrasonic waves propagated in the 2-D covered channel are found to be highly dependent on input frequency and the designed Helmholtz resonator structure, where its negative refractive index causes the focusing phenomenon in this channel. From the numerical simulation and experiments, an amplitude focus spot is observed in the peak-to-peak of the time domain signal and frequency response at 125 kHz by mapping a pressure field in the 2-D covered channel. Different focal points with several input frequencies are also identified. Our research demonstrates the possibility of applying the designed lens based on acoustic metamaterials to improve the focusing effect in ultrasonic testing.

Evaluation of potential probiotic and technological properties of lactic acid bacteria isolated from traditional fermented lap xuong sausage in northwestern Vietnam

Hoang Thi Lan Anh,Le Thi Thanh Hue,Bui Nguyen Hai Linh,Trinh Thanh Trung 한국미생물학회 2023 미생물학회지 Vol.59 No.2

Consumer demand for high-quality and safe fermented meat products is increasing recently, with great attention on functional starter cultures using lactic acid bacteria (LAB). This study aimed to select autochthonous LAB strains that have beneficial effects for human health and technological properties for the production of lap xuong, a traditional fermented sausage of ethnic minorities in northwestern Vietnam. From nine lap xuong samples, 63 LAB strains were isolated and identified into 14 species belonging to 8 genera. Latilactobacillus sakei was the most common species, followed by Lactiplantibacillus plantarum, Lactococcus lactis, and Pediococcus pentosaceus. Five strains of Enterococcus faecium LM0204, Lactococcus lactis LM0302, Latilactobacillus sakei LM0405, Lactiplantibacillus plantarum LM0705, and Lactiplantibacillus plantarum LM0901 exhibited probiotic properties, including tolerance to gastrointestinal tract conditions, adhesion ability to HT-29 cell line, antagonistic activity against harmful bacteria, and antioxidant activities. The strains were further evaluated for technological and safe properties, such as gas production, growth at different temperatures and simulated fermentation and ripening stages, lactic acid production, biogenic amine production, and antibiotic susceptibility. Enterococcus faecium LM0204 and Lactococcus lactis LM0302 were excluded because of tyramine production or unable growth in simulated fermentation conditions. All together probiotic properties and better technical functionality, Latilactobacillus sakei LM0405 and Lactiplantibacillus plantarum LM0705 were proposed as starter cultures for sausage production in northwestern Vietnam. Further studies are needed to standardize the sensory quality and safety aspects of lap xuong in this area using the proposed starter cultures strains for making fermented sausage.

Mitigating Arsenic Accumulation In Rice Plant Using Biofertilizer

Anh T.P. Hoang(Anh),Kyoung-Woong Kim(김경웅) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11

Geochemical constraints on recycled oceanic crust in the mantle source of late Cenozoic basalts from Vietnam

Hoang Thi Hong Anh,Sung Hi Choi,Yongjae Yu,Pham Trung Hieu,Jong-Sik Ryu 대한지질학회 2017 대한지질학회 학술대회 Vol.2017 No.10

Doi Moi and the Remaking of Vietnam

Hoang Anh Tuan 동아시아재단 2009 Global Asia Vol.4 No.3

Double-stranded RNA and food additives for eco-friendly management of insect pest

Hoang Nguyen Minh Anh,Nguyen Thi Thanh Tam,Phan Trinh Yen Binh,Do Thi Dong,Yoo Hee Kim,HongHyun Park,Young Ho Koh 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.04

A Combination of Independent Component Analysis, Relative Wavelet Energy, and Support Vector Machine for Mental State Classification

Hoang-Anh T. Nguyen,Huy-Hoang Tran,Thang T. Vu,T.T. Quyen Bui 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

Mental state classification is an important step for realizing a control system based on electroencephalography (EEG) signals which could benefit a lot of paralyzed people including the locked-in or Amyotrophic Lateral Sclerosis. Considering that EEG signals are nonstationary and often contaminated by various types of artifacts, classifying thoughts into correct mental states is not a trivial problem. In this work, our contribution is that we present and realize a novel model which integrates different techniques: Independent component analysis (ICA), relative wavelet energy, and support vector machine (SVM) for the same task. We applied our model to classify thoughts in two types of experiment whether with two or three mental states. The experimental results show that the presented model outperforms other models using Artificial Neural Network, K-Nearest Neighbors, etc.

Magnetic Properties of Bulk Nd50Co10Fe30Al10-xVx Alloys

Hoang Duc Anh,Cao Xuan Huu,Nguyen Chau,Nguyen Hoang Luong 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

This paper presents the results of study on the structure and the properties of the bulk Nd50Co₁0Fe₃0Al₁0xVx (x = 0, 2, 4, 6, 8, 10) alloys prepared by arc-melting and suction cast- ing with water cooling. The cast surfaces of the samples are partly crystalline and the amorphous volume fraction increases with distance into cast samples. With increasing V content, the crys- tallization volume fraction increases and for x = 10, the alloy is fully crystallized. In general, the melting temperature increases, but Ms and Hc decrease with V content. The Curie temperature increases clearly from 430 K (x = 0) to 512 K (x = 10). Thermomagnetic measurements of all samples done in low elds indicate the existence of the Hopkinson effect, which shows a coherent rotation magnetization and a strong reduction of the magnetic anisotropy in partly crystallized sam- ples. The eld-cooled (FC) and the zero field-cooled (ZFC) curves measured in low elds reveal an obvious separation from each other at low temperatures, pointing to the existence of a cluster-glass state. The cluster-glass fraction decreases with increasing V content in the samples. This paper presents the results of study on the structure and the properties of the bulk Nd50Co₁0Fe₃0Al₁0xVx (x = 0, 2, 4, 6, 8, 10) alloys prepared by arc-melting and suction cast- ing with water cooling. The cast surfaces of the samples are partly crystalline and the amorphous volume fraction increases with distance into cast samples. With increasing V content, the crys- tallization volume fraction increases and for x = 10, the alloy is fully crystallized. In general, the melting temperature increases, but Ms and Hc decrease with V content. The Curie temperature increases clearly from 430 K (x = 0) to 512 K (x = 10). Thermomagnetic measurements of all samples done in low elds indicate the existence of the Hopkinson effect, which shows a coherent rotation magnetization and a strong reduction of the magnetic anisotropy in partly crystallized sam- ples. The eld-cooled (FC) and the zero field-cooled (ZFC) curves measured in low elds reveal an obvious separation from each other at low temperatures, pointing to the existence of a cluster-glass state. The cluster-glass fraction decreases with increasing V content in the samples.

Geochemical constraints on the spatial distribution of recycled oceanic crust in the mantle source of late Cenozoic basalts, Vietnam

Hoang, Thi Hong Anh,Choi, Sung Hi,Yu, Yongjae,Pham, Trung Hieu,Nguyen, Kim Hoang,Ryu, Jong-Sik Elsevier 2018 Lithos Vol.296 No.-

<P><B>Abstract</B></P> <P>This study presents a comprehensive analysis of the major and trace element, mineral, and Sr, Nd, Pb and Mg isotopic compositions of late Cenozoic intraplate basaltic rocks from central and southern Vietnam. The Sr, Nd, and Pb isotopic compositions of these basalts define a tight linear array between Indian mid-ocean-ridge basalt (MORB)-like mantle and enriched mantle type 2 (EM2) components. These basaltic rocks contain low concentrations of CaO (6.4–9.7wt%) and have high Fe/Mn ratios (>60) and FeO/CaO–3MgO/SiO<SUB>2</SUB> values (>0.54), similar to partial melts derived from pyroxenite/eclogite sources. This similarity is also supported by the composition of olivine within these samples, which contains low concentration of Ca and high concentrations of Ni, and shows high Fe/Mn ratios. The basaltic rocks have elevated Dy/Yb ratios that fall within the range of melts derived from garnet lherzolite material, although their Yb contents are much higher than those of modeled melts derived from only garnet lherzolite material and instead plot near the modeled composition of eclogite-derived melts. The Vietnamese basaltic rocks have lighter δ<SUP>26</SUP>Mg values (−0.38±0.06‰) than is expected for the normal mantle (−0.25±0.07‰), and these values decrease with decreasing Hf/Hf* and Ti/Ti* ratios, indicating that these basalts were derived from a source containing carbonate material. On primitive mantle-normalized multi-element variation diagrams, the central Vietnamese basalts are characterized by positive Sr, Eu, and Ba anomalies. These basalts also plot within the pelagic sediment field in PbPb isotopic space. This suggests that the mantle source of the basalts contained both garnet peridotite and recycled oceanic crust. A systematic analysis of variations in geochemical composition in basalts from southern to central Vietnam indicates that the recycled oceanic crust (possibly the paleo-Pacific slab) source material contains varying proportions of gabbro, basalt, and sediment. The basalts from south-central Vietnam (12°N–14°N) may be dominated by the lowest portion of the residual slab that contains rutile-bearing plagioclase-rich gabbroic eclogite, whereas the uppermost portion of the recycled slab, including sediment and basaltic material with small amounts of gabbro, may be a major constituent of the source for the basalts within the central region of Vietnam (14°N–16°N). Finally, the southern region (10°N–12°N) contains basalts sourced mainly from recycled upper oceanic crust that is basalt-rich and contains little or no sediment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Vietnam basalts have Sr-Nd-Pb isotopic compositions defining a DMM-EM2 array. </LI> <LI> The mantle source is composed of garnet peridotite and recycled oceanic crust. </LI> <LI> Southern to central Vietnam can be divided into three geochemical mantle domains. </LI> <LI> Their light Mg isotopic compositions are likely inherited from recycled carbonates. </LI> <LI> The volcanism may be produced by Hainan plume, entraining the Paleo-Pacific slab. </LI> </UL> </P>