An adaptive multi-fidelity sampling framework for safety analysis of connected and automated vehicles

Testing and evaluation are expensive but critical steps in the development of connected and automated vehicles (CAVs). In this paper, we develop an adaptive sampling framework to efficiently evaluate the accident rate of CAVs, particularly for scenario-based tests where the probability distribution of input parameters is known from the Naturalistic Driving Data. Our framework relies on a surrogate model to approximate the CAV performance and a novel acquisition function to maximize the benefit (information to accident rate) of the next sample formulated through an information-theoretic consideration. In addition to the standard application with only a single high-fidelity model of CAV performance, we also extend our approach to the bi-fidelity context where an additional low-fidelity model can be used at a lower computational cost to approximate the CAV performance. Accordingly, for the second case, our approach is formulated such that it allows the choice of the next sample in terms of both fidelity level (i.e., which model to use) and sampling location to maximize the benefit per cost. Our framework is tested in a widely-considered two-dimensional cut-in problem for CAVs, where Intelligent Driving Model (IDM) with different time resolutions are used to construct the high and low-fidelity models. We show that our single-fidelity method outperforms the existing approach for the same problem, and the bi-fidelity method can further save half of the computational cost to reach a similar accuracy in estimating the accident rate

Inverse eigenvalue problems and their associated approximation problems for matrices with J-(Skew) Centrosymmetry

The inverse problems play an important role in MEG reconstructions. In this paper, a partially described inverse eigenvalue problem and an associated optimal approximation problem for J-centrosymmetric matrices are considered respectively. It is shown under which conditions the inverse eigenproblem has a solution. An expression of its general solution is given. In case a solution of the inverse eigenproblem exists, the optimal approximation problem can be solved. The formula of its unique solution is given. Also, the case for J-skew centrosymmetric matrices is considered.Fundação para a Ciência e a Tecnologia (FCT)National Natural Science Foundations of Chin

A BIOMECHANICAL ANALYSIS OF THE UPPER LIMB ON DIFFERENT SNOOKER BATTING TECHNIQUES

The purpose of this study was to compare the kinematics of the upper limb in fellow shot and draw shot, to quantify the effects of the different rods on technical characteristics. Eight professional snooker athletes hit the placed snooker balls using the fellow and draw shots, respectively. Ten kinematic variables were collected for each shot. Paired t-tests were used to analyze the effect of different rod method on the performance of upper limbs. The flexion-extension angle of the elbow (p=0.03) and the hand-rod angle (p=0.02) were larger when the fellow shot was used, while the hitting speed (p=0.01)and the hitting angle (p=0.01) was less than draw shot. Stroke in the draw shot required a large range of elbow and hand-rod angles during the T1-T2 and T2-T3 stages. No statistical differences were found in the kinematics of the wrist. The fellow shot is more stable than the draw shot, and the rod speed may be the main reason for the difference in kinematics between different rod methods