Sketch-based 3D Shape Retrieval using Convolutional Neural Networks

Retrieving 3D models from 2D human sketches has received considerable attention in the areas of graphics, image retrieval, and computer vision. Almost always in state of the art approaches a large amount of "best views" are computed for 3D models, with the hope that the query sketch matches one of these 2D projections of 3D models using predefined features. We argue that this two stage approach (view selection -- matching) is pragmatic but also problematic because the "best views" are subjective and ambiguous, which makes the matching inputs obscure. This imprecise nature of matching further makes it challenging to choose features manually. Instead of relying on the elusive concept of "best views" and the hand-crafted features, we propose to define our views using a minimalism approach and learn features for both sketches and views. Specifically, we drastically reduce the number of views to only two predefined directions for the whole dataset. Then, we learn two Siamese Convolutional Neural Networks (CNNs), one for the views and one for the sketches. The loss function is defined on the within-domain as well as the cross-domain similarities. Our experiments on three benchmark datasets demonstrate that our method is significantly better than state of the art approaches, and outperforms them in all conventional metrics.Comment: CVPR 201

STUDY ON THE INFLUENCE OF CHANGES OF AIR RESISTANCE ATHLETES’ TAKING-OFF SPEED IN FREESTYLE SKIING AERIALS

Freestyle skiing is a competitive sport in the open-air environment. The air resistance that athlete meets in the process of slipping, transition and entering stage determines the athletes’ taking-off speed, thus affecting the performance in competition. This paper set up a function model of frontal area and time about L, T, F, DF, F and other single action in the process completed, and establishes the function between windward area and time in specific action. It studies and analyses the influence of air resistance on athlete’s taking-off speed, combining with the results of the taking-off speed calculation software. The main findings are shown as follows: When the wind speed each increases 0.8 m/s in the leaving platform phase, athlete's taking-off speed will decrease 0.4m/s. When the wind speed is low, the change of wind direction exerts little impact on athletes’ taking-off speed

Robustness, Weak Stability, and Stability in Distribution of Adaptive Filteringalgorithms Under Model Mismatch

This work is concerned with robustness, convergence, and stability of adaptive filtering (AF) type algorithms in the presence of model mismatch. The algorithms under consideration are recursive and have inherent multiscale structure. They can be considered as dynamic systems, in which the `state\u27 changes much more slowly than the perturbing noise. Beyond the existing results on adaptive algorithms, model mismatch significantly affects convergence properties of AF algorithms, raising issues of algorithm robustness. Weak convergence and weak stability (i.e., recurrence) under model mismatch are derived. Based on the limiting stochastic differential equations of suitably scaled iterates, stability in distribution is established. Then algorithms with decreasing step sizes and their convergence properties are examined. When input signals are large, identification bias due to model mismatch will become large and unacceptable. Methods for reducing such bias are introduced when the identified models are used in regulation problems

A New Transfer Impedance Based System Equivalent Model for Voltage Stability Analysis

This paper presents a new transfer impedance based system equivalent model (TISEM) for voltage stability analysis. The TISEM can be used not only to identify the weakest nodes (buses) and system voltage stability, but also to calculate the amount of real and reactive power transferred from the generator nodes to the vulnerable node causing voltage instability. As a result, a full-scale view of voltage stability of the whole system can be presented in front of system operators. This useful information can help operators take proper actions to avoid voltage collapse. The feasibility and effectiveness of the TISEM are further validated in three test systems