RSL autonomous rover

Autonomous vehicles are useful for a variety of applications such as military, urban, and agricultural environments. This paper discusses adding an autonomous navigation system to an all-terrain vehicle by implementing controllers that interface with its current system, installing sensors on the vehicle for obstacle detection, and developing effective safety mechanisms to prevent injury to others. The result is a vehicle capable of waypoint navigation and obstacle avoidance. Testing the vehicle showed that the LIDAR and the autonomous navigation system were integrated seamlessly, and that the sensor output signals were successfully translated into vehicle commands the existing system uses. This system could be improved with further tuning of the PID controller to prevent a large deviation from the defined path. The LIDAR could also be programmed to allow the vehicle to navigate around the obstacle instead of stopping in front of it

Turn the Rudder: A Beacon of Reentrancy Detection for Smart Contracts on Ethereum

Smart contracts are programs deployed on a blockchain and are immutable once deployed. Reentrancy, one of the most important vulnerabilities in smart contracts, has caused millions of dollars in financial loss. Many reentrancy detection approaches have been proposed. It is necessary to investigate the performance of these approaches to provide useful guidelines for their application. In this work, we conduct a large-scale empirical study on the capability of five well-known or recent reentrancy detection tools such as Mythril and Sailfish. We collect 230,548 verified smart contracts from Etherscan and use detection tools to analyze 139,424 contracts after deduplication, which results in 21,212 contracts with reentrancy issues. Then, we manually examine the defective functions located by the tools in the contracts. From the examination results, we obtain 34 true positive contracts with reentrancy and 21,178 false positive contracts without reentrancy. We also analyze the causes of the true and false positives. Finally, we evaluate the tools based on the two kinds of contracts. The results show that more than 99.8% of the reentrant contracts detected by the tools are false positives with eight types of causes, and the tools can only detect the reentrancy issues caused by call.value(), 58.8% of which can be revealed by the Ethereum's official IDE, Remix. Furthermore, we collect real-world reentrancy attacks reported in the past two years and find that the tools fail to find any issues in the corresponding contracts. Based on the findings, existing works on reentrancy detection appear to have very limited capability, and researchers should turn the rudder to discover and detect new reentrancy patterns except those related to call.value().Comment: Accepted by ICSE 2023. Dataset available at https://github.com/InPlusLab/ReentrancyStudy-Dat

Health-related quality of life and its association with socioeconomic status and diet diversity in Chinese older adults

ObjectivesThe study aimed at examining the combined association of socioeconomic status (SES) and diet diversity (DD) with health-related quality of life (HRQoL) and exploring whether DD played a mediating role in the relationship between varied SES and HRQoL among Chinese older persons.MethodA multi-stage random sampling method was conducted in Shanxi Province of China, with 3,250 older adults participating in this cross-sectional survey. SES was divided into groups by quartiles and DD by means, and these variable groups were combined in pairs to generate a total of eight combinations. The PROCESS macro developed by Hayes was employed for the simple mediation analysis.ResultsCompared with the reference group (those with both high SES and high DD), older adults who were classified to have lower SES or DD had elevated odds of having worse HRQoL: low SES/ low DD (OR = 1.65, 95% CI 1.41–2.92); low SES/ high DD (OR = 1.45, 95% CI 1.17–1.80); middle low SES/ low DD (OR = 1.43, 95% CI 1.24–1.65); middle low SES/ high DD (OR = 1.23, 95% CI 1.03–1.47); upper high SES/ low DD (OR = 1.41, 95% CI 1.21–1.65); and high SES/ low DD (OR = 1.30, 95%CI 1.10–1.53). The mediation analysis revealed that DD mediated the relationship between SES and HRQoL (B=0.011, 95% CI 0.008–0.013), with its indirect effects accounting for 39.29% of the total effects.ConclusionsThese findings highlighted the role of DD as a mediator of the relationship between SES and HRQoL. As DD could be protective, modifiable, and easy for older adults to understand and implement, village clinics and community health stations should work collaboratively to design proper DD intervention measures for better HRQoL

The role and effect of damping on the response of a flexible shaft in the region of a critical speed

An experimental study concerned with the role and effect of damping for a rotating flexible shaft in the region of a critical speed is conducted. The existing theory (1) is reviewed for a rotating system with an unbalanced disk in the center of a flexible shaft. The effect of damping on the system is discussed. The experimental results reveal that the external damping plays a role which is taken properly into account by the existing theory. In contract, internal damping does not affect the rotating system in the region of the critical speed.Mechanical Engineering, Department o

A Location and Velocity Prediction-Assisted FANET Networking Scheme for Highly Mobile Scenarios

The proliferation of flying ad hoc networks (FANETs) enables multiple applications in various scenarios. In order to construct and maintain an effective hierarchical structure in FANETs where mobile nodes proceed at high mobility, we propose a novel FANET clustering algorithm by using the Kalman-filter-predicted location and velocity information. First, we use the Silhouette coefficient to determine the number of clusters and the k-means++ method is utilized to group nodes into clusters. Regarding the external disturbances in highly mobile scenarios, a Kalman filter is used to predict locations and velocities for all nodes. When clustering, the relative speeds together with relative distances are considered, and the previous selected cluster heads (CHs) are utilized to initialize current centroids. Furthermore, we propose two metrics, including the cluster stability and the ratio of changed edges, to evaluate the network performance. Relevant simulation results reveal that our proposal can yield a cumulative distribution function (CDF) of cluster stability values close to the sensor-measurement-based data. Moreover, it can reduce communication overheads significantly

Contact-separation-induced self-recoverable mechanoluminescence of CaF2:Tb3+/PDMS elastomer

Abstract Centrosymmetric-oxide/polydimethylsiloxane elastomers emit ultra-strong non-pre-irradiation mechanoluminescence under stress and are considered one of the most ideal mechanoluminescence materials. However, previous centrosymmetric-oxide/polydimethylsiloxane elastomers show severe mechanoluminescence degradation under stretching, which limits their use in applications. Here we show an elastomer based on centrosymmetric fluoride CaF2:Tb3+ and polydimethylsiloxane, with mechanoluminescence that can self-recover after each stretching. Experimentation indicates that the self-recoverable mechanoluminescence of the CaF2:Tb3+/polydimethylsiloxane elastomer occurs essentially due to contact electrification arising from contact-separation interactions between the centrosymmetric phosphors and the polydimethylsiloxane. Accordingly, a contact-separation cycle model of the phosphor–polydimethylsiloxane couple is established, and first-principles calculations are performed to model state energies in the contact-separation cycle. The results reveal that the fluoride–polydimethylsiloxane couple helps to induce contact electrification and maintain the contact-separation cycle at the interface, resulting in the self-recoverable mechanoluminescence of the CaF2:Tb3+/polydimethylsiloxane elastomer. Therefore, it would be a good strategy to develop self-recoverable mechanoluminescence elastomers based on centrosymmetric fluoride phosphors and polydimethylsiloxane