On the definition of Alexandrov space

This paper shows that, in the definition of Alexandrov space with lower ([BGP]) or upper ([AKP]) curvature bound, the original conditions can be replaced with much weaker ones, which can be viewed as comparison versions of the second variation formula in Riemannian geometry (and thus if we define Alexandrov spaces using these weakened conditions, then the original definition will become a local version of Toponogov's Comparison Theorem on such spaces). As an application, we give a new proof for the Doubling Theorem by Perel'man.Comment: 12 page

Evaluation of Load-Bearing Performance of Existing Cast Steel Node

This paper presents a preliminary evaluation of the load-bearing performance of an existing cast steel node in a constructed tennis stadium using numerical simulations and non-destructive field tests. Given the absolute stress values of the existing cast steel node were immeasurable, the accuracy of the numerical simulations were verified by comparing the stress increments derived from numerical simulations and non-destructive field tests. During the experiment, the existing cast steel node was loaded indirectly by moving the retractable roof to three different positions (i.e. closed, semi-opened and fully-opened configurations); thus, only the stress increments were recorded. Three simplified truss models and one solid finite-element model were developed to simulate the stress distributions with the corresponding roof positions. A comparison suggests that the stress increments simulated with the developed finite-element models were in good agreement with experimental results. Therefore, the simulated stress distributions can be used to judge the load-bearing performance of the existing cast steel node

KIT Bus: A Shuttle Model for CARLA Simulator

With the continuous development of science and technology, self-driving vehicles will surely change the nature of transportation and realize the automotive industry\u27s transformation in the future. Compared with self-driving cars, self-driving buses are more efficient in carrying passengers and more environmentally friendly in terms of energy consumption. Therefore, it is speculated that in the future, self-driving buses will become more and more important. As a simulator for autonomous driving research, the CARLA simulator can help people accumulate experience in autonomous driving technology faster and safer. However, a shortcoming is that there is no modern bus model in the CARLA simulator. Consequently, people cannot simulate autonomous driving on buses or the scenarios interacting with buses. Therefore, we built a bus model in 3ds Max software and imported it into the CARLA to fill this gap. Our model, namely KIT bus, is proven to work in the CARLA by testing it with the autopilot simulation. The video demo is shown on our Youtube