Ho Chi Minh City University of Technology

About: Ho Chi Minh City University of Technology is a education organization based out in Ho Chi Minh City, Vietnam. It is known for research contribution in the topics: Computer science & Finite element method. The organization has 3315 authors who have published 4262 publications receiving 32487 citations.

FDM-Based 3D Printing of Polymer and Associated Composite: A Review on Mechanical Properties, Defects and Treatments.

Abstract: Fused deposition modelling (FDM) is one of the fastest-growing additive manufacturing methods used in printing fibre-reinforced composites (FRC). The performances of the resulting printed parts are limited compared to those by other manufacturing methods due to their inherent defects. Hence, the effort to develop treatment methods to overcome these drawbacks has accelerated during the past few years. The main focus of this study is to review the impact of those defects on the mechanical performance of FRC and therefore to discuss the available treatment methods to eliminate or minimize them in order to enhance the functional properties of the printed parts. As FRC is a combination of polymer matrix material and continuous or short reinforcing fibres, this review will thoroughly discuss both thermoplastic polymers and FRCs printed via FDM technology, including the effect of printing parameters such as layer thickness, infill pattern, raster angle and fibre orientation. The most common defects on printed parts, in particular, the void formation, surface roughness and poor bonding between fibre and matrix, are explored. An inclusive discussion on the effectiveness of chemical, laser, heat and ultrasound treatments to minimize these drawbacks is provided by this review.

A conductive topological insulator with large spin Hall effect for ultralow power spin-orbit torque switching.

Abstract: Spin–orbit torque switching using the spin Hall effect in heavy metals and topological insulators has a great potential for ultralow power magnetoresistive random-access memory. To be competitive with conventional spin-transfer torque switching, a pure spin current source with a large spin Hall angle (θSH > 1) and high electrical conductivity (σ > 105 Ω−1 m−1) is required. Here we demonstrate such a pure spin current source: conductive topological insulator BiSb thin films with σ ≈ 2.5 × 105 Ω−1 m−1, θSH ≈ 52 and spin Hall conductivity σSH ≈ 1.3 × 107 $$\frac{\hbar }{{2e}}$$ Ω−1 m−1 at room temperature. We show that BiSb thin films can generate a very large spin–orbit field of 2.3 kOe MA–1 cm2 and a critical switching current density as low as 1.5 MA cm–2 in Bi0.9Sb0.1/MnGa bilayers, which underlines the potential of BiSb for industrial applications. A large spin–orbit torque, generated in a conductive topological insulator (TI) Bi0.9Sb0.1 is further employed to effectively switch the magnetization of MnGa in a BiSb/MnGa bilayer Hall-bar device at room temperature.

Proof-of-Stake Consensus Mechanisms for Future Blockchain Networks: Fundamentals, Applications and Opportunities

Abstract: The rapid development of blockchain technology and their numerous emerging applications has received huge attention in recent years. The distributed consensus mechanism is the backbone of a blockchain network. It plays a key role in ensuring the network’s security, integrity, and performance. Most current blockchain networks have been deploying the proof-of-work consensus mechanisms, in which the consensus is reached through intensive mining processes. However, this mechanism has several limitations, e.g., energy inefficiency, delay, and vulnerable to security threats. To overcome these problems, a new consensus mechanism has been developed recently, namely proof of stake, which enables to achieve the consensus via proving the stake ownership. This mechanism is expected to become a cutting-edge technology for future blockchain networks. This paper is dedicated to investigating proof-of-stake mechanisms, from fundamental knowledge to advanced proof-of-stake-based protocols along with performance analysis, e.g., energy consumption, delay, and security, as well as their promising applications, particularly in the field of Internet of Vehicles. The formation of stake pools and their effects on the network stake distribution are also analyzed and simulated. The results show that the ratio between the block reward and the total network stake has a significant impact on the decentralization of the network. Technical challenges and potential solutions are also discussed.