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A Frequency Domain Equalization Algorithm for Fast Time-Varying Fading Channels
Tran, Le-Nam,Hong, Een-Kee,Liu, Huaping The Korea Institute of Information and Commucation 2009 Journal of communications and networks Vol.11 No.5
Conventional frequency domain equalization (FDE) schemes were originally devised for quasi-static channels. Thus, such equalization schemes could suffer from significant performance degradation in fast-fading channels. This paper proposes a frequency domain equalization algorithm to mitigate the effect of fast time-varying fading. First, a mathematical expression is derived to quantify the total interference resulting from the time variation of the channel. Then, the proposed approach attempts to eliminate the effect of time-variations of the channel. This cancellation allows efficient use of the classical FDE structures in fast time-varying fading environments, although they are built upon the quasi-static channel model. Simulation results of bit-error-rate performance are provided to demonstrate the effectiveness of the proposed algorithm.
On the Precoder Design for Block Diagonalized MIMO Broadcast Channels
Tran, Le-Nam,Juntti, Markku,Hong, Een-Kee IEEE 2012 IEEE communications letters Vol.16 No.8
<P>Block diagonalization (BD) is a linear precoding technique for MIMO broadcast channels such that it completely eliminates the multiuser interference. Consequently, the precoder of a user must lie in the null space of a matrix composing of other users' channel matrices. In this way, the problem of the precoder design is closely related to finding a basis of the null space of the matrix, which can be computed by, e.g., the singular value decomposition (SVD). Recently, a generalized channel inversion (GCI) method was introduced as a low-complexity design for BD. The GCI-based precoder design is also shown to be optimal for BD. However, since the GCI-based design relies on the pseudo-inverse of a matrix, there are many settings, to which this method is not applicable. In this letter, we first provide a connection between the SVD- and GCI-based designs using the results from linear algebra. Then, from this connection, we propose a precoder design that is devised for the cases where the GCI-based method cannot handle.</P>
Le-Phuc Nguyen,Yen Thi Hai Pham,Phuong Thuy Ngo,Tri Van Tran,Loc Vinh Tran,Nam Thi Hoai Le,Luong Huu Nguyen,Tung Thanh Dang,Duc Anh Nguyen,Marco Wenzel,David Hartmann,Karsten Gloe,Jan J. Weigand,Klaus 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5
Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2M HNO3 and a solid-to-liquid ratio of 1/3 at 80 oC in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH1, contact time=10min, and D2EHPA/TBP volume ratio= 4 : 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.
A Frequency Domain Equalization Algorithm for Fast Time-Varying Fading Channels
Le-Nam Tran,Een-Kee Hong,Huaping Liu 한국통신학회 2009 Journal of communications and networks Vol.11 No.5
Conventional frequency domain equalization (FDE) schemes were originally devised for quasi-static channels. Thus, such equalization schemes could suffer from significant performance degradation in fast-fading channels. This paper proposes a frequency domain equalization algorithm to mitigate the effect of fast time-varying fading. First, a mathematical expression is derived to quantify the total interference resulting from the time variation of the channel. Then, the proposed approach attempts to eliminate the effect of time-variations of the channel. This cancellation allows efficient use of the classical FDE structures in fast time-varying fading environments, although they are built upon the quasi-static channel model. Simulation results of bit-error-rate performance are provided to demonstrate the effectiveness of the proposed algorithm.
Tran, Duy Thanh,Hoa, Van Hien,Tuan, Le Huu,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2018 Biosensors & bioelectronics Vol.119 No.-
<P><B>Abstract</B></P> <P>A three-dimensional hierarchical nanohybrid based on Cu-Au bimetallic nanocrystals integrated carbon nanotube arrays vertically grown on carbon spheres was successfully developed as an active platform for sensing application. Such nanohybrid can provide abundant active sites and act as an exceptional platform for immobilizing highly dense and well-dispersed carcinoembryonic antibody (anti-CEA) to sensitively detect CEA, an emerging biomarker of various cancer diseases. Due to the unique nanoarchitecture with altered electronic structure of Cu-Au bimetallic catalyst and enhanced interactions between components, such nanohybrid based biosensor demonstrated excellent electrochemical performance towards CEA detection with great sensitivity, wide linear detection range (0.025–25 ng/mL), very low limit of detection (0.5 pg/mL), and good selectivity. The results imply that this sensor has great potential to offer essential information for cancer diagnosis and management with great clinical importance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A 3D hierarchical Cu-Au nanocrystal integrated CNTs was grown on carbon sphere. </LI> <LI> The hybrid showed a wide linear detection range (0.025–25 ng/mL) and low detection limit (0.5 pg/mL). </LI> <LI> The hybrid showed good reproducibility and accurate detection of CEA in human serum. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Switching and Electrical Memory Effect in the Colossal Permittivity Material La2NiO4+δ
Le Van Hong,Tran Dang Thanh,Dao Nguyen Hoai Nam,,Nguyen Xuan Phuc 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
La2NiO4+δ ceramic samples were manufactured by using a solid state reaction method. The crystalline structural, magnetic and dielectric properties of the material were recorded and analyzed. A dielectric resonance, which is thought to be associated with the multiferroic behavior of the material, was observed at frequencies below 1 MHz. The I/V characteristics were easured on a capacitor-like structure, which exhibited resistance and capacitance switching when opposite voltage pulses of about 2.5 volts with a duration time of 500 ms were applied. The maximum ratios of the changes in the resistance and the capacitance were estimated to be of about 50 % and 35 % at room temperature, respectively. The electrical switching was reversible, with resistive states remaining for a rather long time. The observed capacitance switching and memory effects provide evidence for the presence of charge transfer and accumulation in the material.
Endemic Severe Fever with Thrombocytopenia Syndrome, Vietnam
Tran, Xuan Chuong,Yun, Yeojun,Van An, Le,Kim, So-Hee,Thao, Nguyen T. Phuong,Man, Phan Kim C.,Yoo, Jeong Rae,Heo, Sang Taek,Cho, Nam-Hyuk,Lee, Keun Hwa U.S. Department of Health and Human Services * Cen 2019 Emerging Infectious Diseases Vol.25 No.5
Tran, Tuan Hiep,Nguyen, Hanh Thuy,Le, Nam Van,Tran, Thi Thu Phuong,Lee, Jong Seong,Ku, Sae Kwang,Choi, Han-Gon,Yong, Chul Soon,Kim, Jong Oh Elsevier 2017 International journal of pharmaceutics Vol.528 No.1
<P><B>Abstract</B></P> <P>Heterogeneity of cancer cells and drug resistance require multiple therapeutic approaches for comprehensive treatment. In this study, temperature-sensitive liposomes containing anti-cancer agent tanespimycin (17-AAG) and photosensitizer IR 820 were developed for combination of phototherapy and chemotherapy. The temperature-sensitive liposomes composed of DPPC, cholesterol, DSPE-PEG, 17-AAG, and IR 820 (LP-AI) at weight ratio of 35/15/3/2/2 were formulated as a thin film using extrusion and evaluated for particle size, morphology and drug release profile. Furthermore, the anticancer effect of combined therapy was examined <I>in vitro</I> and <I>in vivo</I> in SCC-7 and MCF-7 cell lines. As a result, LP-AI was prepared at particle size of 166.7±1.3nm, PDI of 0.153±0.012, and ζ-potential of −32.6±0.8mV. After NIR irradiation (660 and 808nm laser), LP-AI could generate heat and ROS and enhance drug release from nanoparticles which were useful to kill the cancer cells. These were confirmed by <I>in vitro</I> cytotoxicity as well as <I>in vivo</I> effective ablation of tumors. In conclusion, fast drug release and enhanced treatment efficacy of LP-AI indicate the potential of integrating photo- and chemotherapy for synergistic anti-cancer effects.</P> <P><B>Graphical abstract</B></P> <P>Temperature-sensitive liposomes containing anti-cancer agent tanespimycin and photosensitizer IR 820 (LP-AI).</P> <P>[DISPLAY OMISSION]</P>