This study aimed to explore how autonomous vehicles can predict potential risks and efficiently pass through the dangerous interaction areas in the face of occluded scenes or limited visual scope. ...First, a Dynamic Bayesian Network based model for real-time assessment of potential risks is proposed, which enables autonomous vehicles to observe the surrounding risk factors, and infer and quantify the potential risks at the visually occluded areas. The risk distance coefficient is established to integrate the perception interaction ability of traffic participants into the model. Second, the predicted potential risk is applied to vehicle motion planning. The vehicle movement is improved by adjusting the speed and heading angle control. Finally, a dynamic simulation platform is built to verify the proposed model in two specific scenarios of view occlusion. The model has been compared with the existing methods, the autonomous vehicles can accurately assess the potential danger of the occluded areas in real-time and can safely, comfortably, and effectively pass through the dangerous interaction areas.
Autonomous vehicles for the intention of human behavior of the estimated traffic participants and their interaction is the main problem in automatic driving system. Classical cognitive theory assumes ...that the behavior of human traffic participants is completely reasonable when studying estimation of intention and interaction. However, according to the quantum cognition and decision theory as well as practical traffic cases, human behavior including traffic behavior is often unreasonable, which violates classical cognition and decision theory. Based on the quantum cognitive theory, this paper studies the cognitive problem of pedestrian crossing. Through the case analysis, it is proved that the Quantum-like Bayesian (QLB) model can consider the reasonability of pedestrians when crossing the street compared with the classical probability model, being more consistent with the actual situation. The experiment of trajectory prediction proves that the QLB model can cover the edge events in interactive scenes compared with the data-driven Social-LSTM model, being more consistent with the real trajectory. This paper provides a new reference for the research on the cognitive problem of intention on bounded rational behavior of human traffic participants in autonomous driving.
Atomically thin hexagonal boron nitride (h‐BN) is gaining significant attention for many applications such as a dielectric layer or substrate for graphene‐based devices. For these applications, ...synthesis of high‐quality and large‐area h‐BN layers with few defects is strongly desirable. In this work, the aligned growth of millimeter‐size single‐crystal h‐BN domains on epitaxial Ni (111)/sapphire substrates by ion beam sputtering deposition is demonstrated. Under the optimized growth conditions, single‐crystal h‐BN domains up to 0.6 mm in edge length are obtained, the largest reported to date. The formation of large‐size h‐BN domains results mainly from the reduced Ni‐grain boundaries and the improved crystallinity of Ni film. Furthermore, the h‐BN domains show well‐aligned orientation and excellent dielectric properties. In addition, the sapphire substrates can be repeatedly used with almost no limit. This work provides an effective approach for synthesizing large‐scale high‐quality h‐BN layers for electronic applications.
The aligned growth of 0.6 mm single‐crystal hexagonal boron nitride (h‐BN) domains is realized on epitaxial Ni(111)/sapphire by ion beam sputtering deposition. The formation of large‐size h‐BN domains results mainly from the reduced Ni‐grain boundaries and the improved crystallinity of the Ni film. In addition, the h‐BN domains show well‐aligned orientation and excellent dielectric properties.
Abstract
The behavior intention estimation and interaction between Autonomous Vehicles (AV) and human traffic participants are the key problems in Automatic Driving System (ADS). When the classical ...decision theory studies implicitly assume that the behavior of human traffic participants is completely rational. However, according to the booming quantum decision theory in recent years and actual traffic cases, traffic behaviors and other human behaviors are often irrational and violate the assumptions of classical cognitive and decision theory. This paper explores the decision-making problem in the two-car game scene based on quantum decision theory and compares it with the current mainstream method of studying irrational behavior-Cumulative Prospect Theory (CPT) model. The comparative analysis proved that the Quantum Game Theory (QGT) model can explain the separation effect which the classical probability model can’t reveal, and it has more advantages than CPT model in dealing with game scene decision-making. When two cars interact with each other, the QGT model can consider the interests of both sides from the perspective of the other car. Compared with the classical probability model and CPT model, the QGT is more realistic in the behavior decision-making of ADS.
Hafnium disulfide (HfS2) has attracted significant interest because of the predicted excellent electronic properties superior to group VIB transition metal dichalcogenides. On the other hand, ...atomically thin hexagonal boron nitride (h-BN) is an ideal dielectric substrate for optoelectronic applications of other 2D materials. Here, for the first time, we report the direct growth of high-quality atomic layered HfS2 on few-layer h-BN transferred on SiO2/Si substrates by chemical vapor deposition. It was found that the HfS2 layers are selectively grown on h-BN rather than on SiO2/Si. Density functional theory calculations are performed to help understand the mechanism of selective growth of HfS2. Furthermore, the photodetectors based on the HfS2/h-BN heterostructures exhibit excellent visible-light sensing performance, such as a high on/off ratio of more than 105, an ultrafast response rate of about 200 μs, a high responsivity of 26.5 mA W–1, and a competitive detectivity exceeding 3 × 1011 Jones, superior to the vast majority of the reported 2D materials based photodetectors. The remarkable performance of the HfS2/h-BN photodetector is attributed to the unique features of 2D h-BN substrate.
Motion planning for autonomous vehicles remains a challenge in urban road environments with occlusions. In this study, we present a motion planning framework that prioritizes safety, comfort, and ...efficiency to enable autonomous vehicles to navigate safely through urban roads with occlusions. Our solution consists of three main components: local path planning, trajectory planning, and speed planning. First, based on the improved Artificial Potential Field to generate the local path, then the optimal trajectory is solved in the S-L coordinate with the local path as the reference line. Subsequently, the potential risk probability of the occluded area is incorporated into the incomplete information static game framework and implement speed planning based on the game results and the proposed vehicle "safe driving" to complete the collision avoidance between the autonomous vehicle and visible or obscured dynamic traffic participants. In high pedestrian traffic scenarios, simulation verification shows that the proposed model enhances autonomous vehicle comfort levels by about 32%<inline-formula> <tex-math notation="LaTeX">\sim </tex-math></inline-formula>48% compared to the baseline method utilizing automatic emergency brake system (AEB). We also conducted simulation verification of the proposed model in overtaking and left-turning traffic scenarios, comparing it with other models. The results demonstrate that our proposed model ensures safe autonomous driving in traffic scenario with occlusions while maintaining comfort and efficiency.
Abstract
Background
To evaluate the safety and effectiveness of different dosages of intranasal Dexmedetomidine (DEX) in combination with oral midazolam for sedation of young children during brain ...MRI examination.
Methods
Included in this prospective single-blind randomized controlled trial were 156 children aged from 3 months to 6 years and weighing from 4 to 20 Kg with ASA I-II who underwent brain MRI examination between March 2021 and February 2022. Using the random number table method, they were divided into group A (using 3 ug/kg intranasal DEX plus 0.2 mg/Kg oral midazolam) and group B (using 2 ug/kg intranasal DEX plus 0.2 mg/Kg oral Midazolam). The one-time success rate of sedation, sedation onset time, recovery time, overall sedation time, and occurrence of adverse reactions during MRI examination were compared between the two groups. The heart rate (HR), mean arterial pressure (MAP), and percutaneous SpO
2
before and after drug administration were observed in both groups. Differences in sedation scores between the two groups were compared before intranasal drug administration (T0), 10 min after drug administration (T1), at the time of falling asleep (T2), at the end of examination (T3), and at the time of recovery (T4).
Results
The one-time success rate of sedation in group A and B was 88.31% and 79.75% respectively, showing no significant difference between the two groups (
P
>0.05). The sedation onset time in group A was 24.97±16.94 min versus 27.92±15.83 min in group B, and the recovery time was 61.88±22.18 min versus 61.16±28.16 min, both showing no significance difference between the two groups (
P
>0.05). Children in both groups exhibited good drug tolerance without presenting nausea and vomiting, hypoxia, or bradycardia and hypotension that needed clinical interventions. There was no significant difference in the occurrence of abnormal HR, MAP or other adverse reactions between the two groups (
P
>0.05).
Conclusion
3 ug/kg or 2 ug/kg intranasal DEX in combination with 0.2 mg/kg oral Midazolam both are safe and effective for sedation of children undergoing MRI examination with the advantages of fast-acting and easy application.
Trial registration
It was registered at the Chinese Clinical Trial Registry (
ChiCTR1800015038
) on 02/03/2018.
Commercially available AlGaN/GaN high-electron-mobility transistors (HEMTs) are beginning to enter the public scene from a range of suppliers. Based on previous studies, commercial GaN-based ...electronics are expected to be tolerant to different types of irradiation in space. To test this assumption, we compared the characteristic electrical curves obtained at different X-ray irradiation doses for GaN HEMT devices manufactured by Infineon and Transphorm. The p-GaN-based device was found to be more robust with a stable threshold voltage, whereas the threshold voltage of the device with a metal-insulator-semiconductor gate was found to shift first in the negative and then the positive direction. This dynamic phenomenon is caused by the releasing and trapping effects of radiation-induced charges in the dielectric layer and at the interface of irradiated devices. As such, the p-GaN-gate-based GaN HEMT provides a promising solution for use as an electric source in space.
•GaN MIS-HEMT together with p-GaN gate based GaN device are compared under different X-ray irradiation doses.•Dynamic phenomenon in threshold voltage of GaN MIS-HEMT after X-ray irradiation is deeply discussed.•Enhancement-mode GaN HEMT fabricated using p-GaN gate has a stable threshold voltage, possessing huge potential in space use of electric source.
STC90C516RD + microcontroller was chosen as the core controller of AGV. The magnetic line was detected by Hall sensor, the tracking function of AGV is realized, the ultrasonic ranging function was ...used to avoid obstacles, and the differential steering of the car was realized by using the output PWM wave, after installation and debugging, AGV can basically achieve the requirement of conveying objects.
The rational design of hierarchical hollow nanomaterials is of critical significance in energy storage materials. Herein, dual-wall hollow nanospheres (DWHNS) Sn/MoS2@C are constructed by in situ ...confined growth and interface engineering. The inner hollow spheres of Sn/MoS2 are formed by atomic soldering MoS2 nanosheets with liquid Sn at high temperature. The formation mechanism of the hierarchical structure is explored by the morphology evolutions at different temperatures. The DWHNS Sn/MoS2@C manifest abundant inner space and high specific surface area, which provides more support sites for Li+/Na+/K+ storage and alleviates the volume effect of tin-based electrode materials to a certain extent. The composite material manifests an outstanding specific capacity and satisfactory reversibility of lithium ion batteries (∼931 mAh g–1 at 1 A g–1 after 500 cycles), sodium ion batteries (∼432 mAh g–1 at 1 A g–1 after 400 cycles), and potassium ion batteries (∼226 mAh g–1 at 1 A g–1 after 300 cycles). Additionally, the morphology evolution and mechanism analysis of DWHNS Sn/MoS2@C in alkali metal ion batteries are verified by ex situ measurement, which confirms the three-in-one hybrid storage mechanism, i.e., intercalation reaction of carbon shells, conversion reaction of MoS2, and alloying reaction of tin.
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