Three-dimensional ultrafast charge-density-wave dynamics in CuTe.

Charge density waves (CDWs) involved with electronic and phononic subsystems simultaneously are a common quantum state in solid-state physics, especially in low-dimensional materials. However, CDW phase dynamics in various dimensions are yet to be studied, and their phase transition mechanism is currently moot. Here we show that using the distinct temperature evolution of orientation-dependent ultrafast electron and phonon dynamics, different dimensional CDW phases are verified in CuTe. When the temperature decreases, the shrinking of c-axis length accompanied with the appearance of interchain and interlayer interactions causes the quantum fluctuations (QF) of the CDW phase until 220 K. At T < 220 K, the CDWs on the different ab-planes are finally locked with each other in anti-phase to form a CDW phase along the c-axis. This study shows the dimension evolution of CDW phases in one CDW system and their stabilized mechanisms in different temperature regimes.

Bandgap Shrinkage and Charge Transfer in 2D Layered SnS2 Doped with V for Photocatalytic Efficiency Improvement.

Effects of electronic and atomic structures of V-doped 2D layered SnS2 are studied using X-ray spectroscopy for the development of photocatalytic/photovoltaic applications. Extended X-ray absorption fine structure measurements at V K-edge reveal the presence of VO and VS bonds which form the intercalation of tetrahedral OVS sites in the van der Waals (vdW) gap of SnS2 layers. X-ray absorption near-edge structure (XANES) reveals not only valence state of V dopant in SnS2 is ≈4+ but also the charge transfer (CT) from V to ligands, supported by V Lα,ß resonant inelastic X-ray scattering. These results suggest V doping produces extra interlayer covalent interactions and additional conducting channels, which increase the electronic conductivity and CT. This gives rapid transport of photo-excited electrons and effective carrier separation in layered SnS2 . Additionally, valence-band photoemission spectra and S K-edge XANES indicate that the density of states near/at valence-band maximum is shifted to lower binding energy in V-doped SnS2 compare to pristine SnS2 and exhibits band gap shrinkage. These findings support first-principles density functional theory calculations of the interstitially tetrahedral OVS site intercalated in the vdW gap, highlighting the CT from V to ligands in V-doped SnS2 .

Design of a FlexRay/Ethernet Gateway and Security Mechanism for In-Vehicle Networks.

Due to the development of the Internet of Vehicles (IoV) and advanced driver-assistance systems (ADAS), the Ethernet has become one of the most important communication protocols for the future of automotive networks. This is because the existing communication protocols (such as FlexRay) do not provide sufficiently high bandwidth requirements. The main challenge for the automotive industry will be to transfer and extend standard IP and Ethernet into vehicles and still fulfill the automotive requirements. The automotive gateway not only links two or more protocols and exchanges the data using each, but also monitors and ensures functional safety. This paper proposes a FlexRay/Ethernet gateway by considering the development conditions of embedded systems and the security in the field of vehicle networking. The proposed method is implemented on the Field Programmable Gate Array (FPGA) system to evaluate running time and to analyze the overhead of the security mechanism. For one-to-one mapping logic, the execution times of FlexRay to the Ethernet path and Ethernet to FlexRay path are constant, at 4.67 µs and 6.71 µs, respectively. In particular, cybersecurity can be integrated as an extension of the gateway with low latency and power consumption.

A Reliability Scheduling Algorithm for the Static Segment of FlexRay on Vehicle Networks.

FlexRay is a next-generation in-vehicle communication protocol which works in real time with flexibility. The most common applications in FlexRay are high bandwidth. X-by-wire applications, such as brake by wire and throttle by wire. However, there is no mechanism which can prevent transient faults in the application layer of FlexRay. If a transient fault occurs during driving, this would be very dangerous; therefore, we propose a fast reliability scheduling algorithm (FRSA) to improve the communication reliability of FlexRay. The proposed method reduces the probability of transient faults in one clock cycle by using a retransmission mechanism to recover the transient errors, and further improves computational complexity using the lookup table method to ensure system reliability. In this paper, we analyze a related literature to establish the system reliability constraints needed to evaluate the necessary time and slot usage, and the proposed cost function is used to evaluate the performance and efficiency when the number of messages is increased. Experimental results show that the proposed FRSA reduces execution time by an average 70.76% and cost by an average 13.33% more than the other existing methods. This method can be useful to others, especially regarding research about periodic time-triggered communication systems.