Efficient Processing of k Nearest Neighbor Joins using MapReduce

k nearest neighbor join (kNN join), designed to find k nearest neighbors from a dataset S for every object in another dataset R, is a primitive operation widely adopted by many data mining applications. As a combination of the k nearest neighbor query and the join operation, kNN join is an expensive operation. Given the increasing volume of data, it is difficult to perform a kNN join on a centralized machine efficiently. In this paper, we investigate how to perform kNN join using MapReduce which is a well-accepted framework for data-intensive applications over clusters of computers. In brief, the mappers cluster objects into groups; the reducers perform the kNN join on each group of objects separately. We design an effective mapping mechanism that exploits pruning rules for distance filtering, and hence reduces both the shuffling and computational costs. To reduce the shuffling cost, we propose two approximate algorithms to minimize the number of replicas. Extensive experiments on our in-house cluster demonstrate that our proposed methods are efficient, robust and scalable.Comment: VLDB201

EFFECTS OF EXERCISE FATIGUE ON PLANTAR PRESSURE IN BADMINTON : A EXPLORATORY STUDY

The purpose of present study was to evaluate the effect of exercise fatigue on plantar pressure in badminton. One badminton athlete volunteer without any injury or disease in the latest 3 months attended this study. Peak pressure(PP) and integration of pressure and duration(Pt) of pelma pre- and post-fatigue were measured. Results show that PP of heel was the highest. After fatigue, the PP of heel and Pt of metatarsal were increased significantly, and the Pt of heel was decreased significantly. In badminton training, it's necessary to enhance muscular strength and arrange training intensity for individual. More and deeply biomechanical research should be done to lessen pain and injury

Just Looking: Tourist Gaze and the Theme Park Experience

What makes a memorable theme park experience? New research led by UCF Rosen College of Hospitality Management\u27s Assistant Professor Wei Wei looks at how visitor experience is influenced by the \u27tourist gaze\u27—the consumption of visual experiences, as well as other services, in a tourism destination. With important implications for theme park operators and managers, the study focuses on visitors\u27 visual interactions with fellow visitors and finds they have a significant impact on visitors\u27 emotions and the quality of their overall experience