RFID-Based Vehicle Positioning and Its Applications in Connected Vehicles

This paper proposed an RFID-based vehicle positioning approach to facilitate connected vehicles applications. When a vehicle passes over an RFID tag, the vehicle position is given by the accurate position stored in the tag. At locations without RFID coverage, the vehicle position is estimated from the most recent tag location using a kinematics integration algorithm till updates from the next tag. The accuracy of RFID positioning is verified empirically in two independent ways with one using radar and the other a photoelectric switch. The former is designed to verify whether the dynamic position obtained from RFID tags matches the position measured by radar that is regarded as accurate. The latter aims to verify whether the position estimated from the kinematics integration matches the position obtained from RFID tags. Both means supports the accuracy of RFID-based positioning. As a supplement to GPS which suffers from issues such as inaccuracy and loss of signal, RFID positioning is promising in facilitating connected vehicles applications. Two conceptual applications are provided here with one in vehicle operational control and the other in Level IV intersection control

Advances on in situ TEM mechanical testing techniques: a retrospective and perspective view

Over the past few decades, in situ transmission electron microscopy (TEM) has emerged as a powerful experimental technique for materials design and characterization. It offers unparalleled dynamic details of materials deformation under mechanical stimuli, providing fundamental insights into their deformation and failure mechanisms for various materials. In this review, we summarize recent advances on in situ TEM mechanical characterization techniques, including classical tension holders, nanoindentation holders, MEMS devices, thermal bimetallic-based techniques, and nanomanipulation techniques. The advantages and limitations of in situ TEM tests are also discussed. To provide a broader perspective, the article highlights promising opportunities for in situ TEM mechanical testing studies in characterization-processing-manufacturing based on nanomanipulation, ultrafast TEM, electron beam irradiation environmental conditions, data-driven machine learning, and integrated experimental and simulation characterization. This article aims to provide a comprehensive understanding of in situ TEM-based mechanical characterization techniques to promote the development of novel materials with improved mechanical properties for various applications

Balance Between Cost and Risk for Fund Manager When Adopting Diversification Method

Following the 2007-2008 financial crisis and acceleration of economic globalization, more market participants and regulators pay more attention to the role of portfolio diversification strategy in financial market. Various diversification strategies are applied by fund managers to reduce the idiosyncratic risk, including the Most Diversified Portfolio (MDP), Minimum Variance portfolio, Equally Weighted portfolio and Maximum Sharpe Ratio method. The paper describes how the diversification strategy improve the performance of investment portfolio and tries to find a optimal portfolio size for fund managers. A variety of quantitative methods are applied in the analysis including OLS regression, stationary test and Monte Carlo simulation with R. The analysis results have shown that there exists a trade-off between efficiency of diversification and downside risk of asset price. Furthermore, the optimal portfolio size is estimated using the Most Diversified Portfolio Method

Stability and scalability of homogeneous vehicular platoon: study on the influence of information flow topologies

In addition to decentralized controllers, the information flow among vehicles can significantly affect the dynamics of a platoon. This paper studies the influence of information flow topology on the internal stability and scalability of homogeneous vehicular platoons moving in a rigid formation. A linearized vehicle longitudinal dynamic model is derived using the exact feedback linearization technique, which accommodates the inertial delay of powertrain dynamics. Directed graphs are adopted to describe different types of allowable information flow interconnecting vehicles, including both radar-based sensors and vehicle-to-vehicle (V2V) communications. Under linear feedback controllers, a unified internal stability theorem is proved by using the algebraic graph theory and Routh-Hurwitz stability criterion. The theorem explicitly establishes the stabilizing thresholds of linear controller gains for platoons, under a large class of different information flow topologies. Using matrix eigenvalue analysis, the scalability is investigated for platoons under two typical information flow topologies, i.e., 1) the stability margin of platoon decays to zero as 0(1/N2) for bidirectional topology; and 2) the stability margin is always bounded and independent of the platoon size for bidirectional-leader topology. Numerical simulations are used to illustrate the results

Cloud Control of Connected Vehicle under Bi-directional Time-varying delay: An Application of Predictor-observer Structured Controller

This article is devoted to addressing the cloud control of connected vehicles, specifically focusing on analyzing the effect of bi-directional communication-induced delays. To mitigate the adverse effects of such delays, a novel predictor-observer structured controller is proposed which compensate for both measurable output delays and unmeasurable, yet bounded, input delays simultaneously. The study begins by novelly constructing an equivalent delay-free inter-connected system model that incorporates the Predictor-Observer controller, considering certain delay boundaries and model uncertainties. Subsequently, a stability analysis is conducted to assess the system's robustness under these conditions. Next, the connected vehicle lateral control scenario is built which contain high-fidelity vehicle dynamic model. The results demonstrate the controller's ability to accurately predict the system states, even under time-varying bi-directional delays. Finally, the proposed method is deployed in a real connected vehicle lateral control system. Comparative tests with a conventional linear feedback controller showcase significantly improved control performance under dominant bi-directional delay conditions, affirming the superiority of the proposed method against the delay