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382 results on '"Chengcui Zhang"'

1. A method for measuring human body composition using digital images.

Author

Olivia Affuso, Ligaj Pradhan, Chengcui Zhang, Song Gao, Howard W Wiener, Barbara Gower, Steven B Heymsfield, and David B Allison

Subjects
Medicine, Science
Abstract

BACKGROUND/OBJECTIVES:Body mass index (BMI) is a proxy for obesity that is commonly used in spite of its limitation in estimating body fatness. Trained observers with repeated exposure to different body types can estimate body fat (BF) of individuals compared to criterion methods with reasonable accuracy. The purpose of this study was to develop and validate a computer algorithm to provide a valid estimate %BF using digital photographs. SUBJECTS/METHODS:Our sample included 97 children and 226 adults (age in years: 11.3±3.3; 38.1±11.6, respectively). Measured height and weight were used (BMI in kg/m2: 20.4±4.4; 28.7±6.6 for children and adults, respectively). Dual x-ray absorptiometry (DXA) was the criterion method. Body volume (BVPHOTO) and body shape (BSPHOTO) were derived from two digital images. Final support vector regression (SVR) models were trained using age, sex, race, BMI for % BFNOPHOTO, plus BVPHOTO and BSPHOTO for %BFPHOTO. Separate validation models were used to evaluate the learning algorithm in children and adults. The differences in correlations between %BFDXA, %BFNOPHOTO and %BFPHOTO were tested using the Fisher's Z-score transformation. RESULTS:Mean BFDXA and BFPHOTO were 27.0%±9.2 vs. 26.7%± 7.4 in children and 32.9± 10.4% vs. 32.8%±9.3 in adults. SVR models produced %BFPHOTO values strongly correlated with %BFDXA. Our final model produced correlations of rDP = 0.80 and rDP = 0.87 in children and adults, respectively for %BFPHOTO vs. %BFDXA. The correlation between %BFNOPHOTO and %BFDXA was moderate, yet statistically significant in both children rDB = 0.70; p

Published
2018
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47. Stochastic Game in Linear Quadratic Gaussian Control for Wireless Networked Control Systems Under DoS Attacks

Author

Jitao Sun, Chengcui Zhang, and Junhui Zhang

Subjects
0209 industrial biotechnology, Mathematical optimization, Network packet, business.industry, Computer science, Stochastic game, 020206 networking & telecommunications, Denial-of-service attack, 02 engineering and technology, Linear-quadratic-Gaussian control, Computer Science Applications, Human-Computer Interaction, 020901 industrial engineering & automation, Control and Systems Engineering, Control system, 0202 electrical engineering, electronic engineering, information engineering, Wireless, Electrical and Electronic Engineering, business, Software, Computer Science::Cryptography and Security, Communication channel
Abstract

Recently, the security problem of wireless networked control systems (WNCSs) has become critical. In this article, we focus on strategies designing problem for sensor and denial-of-service (DoS) attacker in WNCS based on linear quadratic Gaussian (LQG) cost. In this scenario, a sensor measures the output of the system and transmits its local state estimate to the remote estimator via an unreliable channel which may suffer interference from an intelligent DoS attacker. In each step, the sensor demands to determine the power to transmit its packet data, at the same time, the attacker needs to determine the interference power to degrade the performance of the WNCS. To analyze this interactive decision-making process, we construct a two-player zero-sum stochastic game and propose an improved LQG cost considering energy-efficient factors. Then, for continuous power-level setting, we discuss the existence and the structure of equilibrium strategies of the sensor-attacker game. For a discrete power set, an algorithm is developed to solve equilibrium strategies for both players. Finally, we present an example to illustrate our results.

Published
2022

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