Search
Author
- Anh-Tuan Le (11)
- Quan-Hoang Vuong (8)
- Ngo Xuan Dinh (7)
- Quan, Hoang Vuong (6)
- next >
Subject
- Compound droplet (3)
- Simulation (3)
- Economics (2)
- Front-tracking (2)
- next >
Search Results
We demonstrate a multifunctional metamaterial (MM) structure which can behave like a perfect absorber (PA) or polarization converter (PC) by controlling the lumped varactor. In PC mode, the MM revealed cross-polarization conversion in a frequency range from 2.0 to 7.0 GHz with a polarization-conversion ratio of nearly 100%. While in the PA state, triple-band high absorption was achieved. In addition, we investigated numerically the PA and PC modes by scaling down the geometrical dimension and orientation of the proposed unit cells, for further development of innovative methods in the THz range. Our work is expected to contribute to the realization of future multifunctional MM-based devices working in the GHz or higher-frequency range. |
Improving engine power density by using supercharging system with exhaust gas energy recovery (called an exhaust gas turbocharger) is a trend of improving non-turbocharged base engines in Vietnam. These engines are still capable of being used for a considerable time, but the power generating is not big enough to meet the requirements of improving vehicle maneuverability, especially special vehicles such us Russian or Vietnamese tanks. To determine the maximum level of pressure ratio of the engine according to the engine thermal load criteria, we can use direct and indirect indicators. The content of the paper is to determine the heat flow density for cooling water in the V12 engine according to the different pressure ratios. From that, the maximum level of pressure ratio for the eng... |
Different countries have responded to the pandemic with distinct domestic and international travel restrictions. The purpose of this paper is to investigate the stringency of the coronavirus disease 2019 (COVID-19) countermeasures in Japan against their G20 cohorts. Primary data were monitored at a ski resort in Kyushu regarding the social acceptance of initial COVID-19 countermeasures, ranging from hygiene and local “lockdowns” to border control measures. |
Satirical cartooning in Vietnam is subject to a complex dynamic: an increasingly liberalised and internationalised economy, and the rise of social media in a one-party state. This article examines what state-sanctioned satirical cartoons can reveal about the representation and management of political criticism in such a context. We find a growing trend of depicting corruption as a systemic problem, which is present in 45 per cent of the sample and in 70 per cent of the 20 most-viral cartoons in one of Vietnam’s most popular magazines, Tuoi Tre Cuoi (Youth Humour). This trend can be interpreted as a change in the sensibility of audiences and a shift toward a more tolerant media landscape. The trend, however, may also be a worrying sign of the dual dangers of cynicism in Vietnamese po... |
In this paper, we report a simple method for enhancing the electrical property of silver nanowire transparent conductive electrodes (AgNW-TCE). When scotch tape was attached to the surface of AgNW-TCE and then removed, the sheet resistance of the AgNW-TCE was drastically decreased, while the transmittance was insignificantly lost; namely, the sheet resistance was reduced from 98.5 Ω/□ to 27.3 Ω/□ and the transmittance was decreased from 92% to 89%. The improved sheet resistance could be due to the transfer of the glue on the tape onto the AgNW-TCE, resulting in better contact at the junction between AgNWs. |
In this paper, a new design of the state observer is proposed to reduce the unstable low-speed region of the adaptive full-order observer (AFO) based speed sensorless speed control of induction motors (IM). The proposed state observer is designed in z-domain rather than in s-domain following the pole-placement approach. The convergence rate of the proposed observer can be made faster than that of the IM poles without extra oscillation effects and the unstable low-speed region of AFO can be reduced to the zero-synchronous-frequency (ZSF) line. Also, a modified adaptation law of the AFO is derived to estimate the rotor speed. Based on the modified AFO, a continuous control set model predictive control (CCS-MPC) is designed for the inner-loop torque control. The cost function of the CC... |
This letter proposes novel methods for designing two-dimensional (2-D) weight-constrained codes for reducing the parasitic currents in the crossbar resistive memory array. In particular, we present efficient encoding/decoding algorithms for capacity-approaching 2-D weight-constrained codes of size m×n , where each row has a weight pn with p<1/2 ; and each column has a weight qm with q≤1/2 . We show that the designed codes provide higher code rates compared to the prior art codes for p≤1/2 and q≤1/2 . |
Recently, dislocation in single-crystal silicon has been confirmed to be induced by fatigue. It was found that the fatigue lifetime of silicon is likely to be dominated by accumulation of crystal defects, i.e., dislocations. In previous studies, crystal d |
In this article, we investigate the dynamic network service provider (SP) and service selection in a user-centric network. Here, the network services are different combinations of network resources. In particular, we consider an intelligent reflecting surface (IRS)-assisted wireless network in which mobile users select different network resources, i.e., transmit power and IRS resources, provided by different SPs. To analyze the SP and service selection of the users, we propose to use an evolutionary game. In the game, the users (players) adjust their selections of the SPs and services based on their utilities. We model the SP and service adaptation of the users by the replicator dynamics and analyze the equilibrium of the evolutionary game. Extensive simulations are provided to demo... |
In this study, the solidification process of a compound droplet is numerically simulated by an axisymmetric front-tracking/finite difference technique. The compound droplet placed on a cold flat surface in a gas environment consists of an inner gas core surrounded by a concentric shell phase-change liquid that forms an outer droplet. The initial droplet shape assumed as a spherical cap is therefore determined by two wetting angles known as the inner wetting angle (?0i for the inner core) and the outer wetting angle (?0o for the outer droplet). During the solidification process, there is the presence of two three-junction points where a prescribed growth angle ? is specified. We analyze the solidification process undergoing the influence of the geometrical aspects of the compound dro... |
