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Xianning, China

Zhou F.,Xianning University
Proceedings - 2011 7th International Conference on Natural Computation, ICNC 2011 | Year: 2011

This paper investigates the target coverage problem in wireless sensor networks with continuously adjustable sensing range. We study a wireless sensor network consisting a large number of N sensors that are randomly deployed over an area of interest and are expected to cover a number of M targets for a period of time as long as possible. For each sensor, the operation of sensing may consume energy which varies with different sensing ranges for which it may operate. Since targets are redundantly covered by multiple sensors, to conserve energy resources, sensors can be organized into a number of non-disjoint sets and activate them set by set. We define the maximal lifetime with constrained energy (MLCE) problem that has its objective of finding the operation time to each set of sensors such that the total operation time is maximized. Since the MLCE problem is NP-complete, two greedy heuristics is designed for solving this problem. © 2011 IEEE. Source

Cheng Y.,Central China Normal University | Yang H.,Central China Normal University | Cheng Z.,Xianning University | Xiao B.,Yangtze University
Photonics and Nanostructures - Fundamentals and Applications | Year: 2011

The model of the polarization-insensitive metamaterial (MM) absorber composed of split cross-ring resonator (SCRR), cave-cross resonator (CCR) and dielectric substrate was proposed at microwave frequencies. Based on perfect impedance-matched (z̃(ω)=1) to the free space, the single unit cell could achieve near-unity absorbance by properly assembling the sandwich structure. We have simulated and measured the reflectivity and transmission properties of a planar MM absorber with the thickness of 0.6 mm. The absorptivity of a single layer MM absorber achieve greater than 96% around 10.07 GHz in experiments and 98% in simulations for incident electromagnetic (EM) wave with different polarizations. © 2010 Elsevier B.V. All rights reserved. Source

Sun J.,Xianning University | Ponce J.,Ecole Normale Superieure de Paris
International Journal of Computer Vision | Year: 2016

This paper proposes a novel approach to learning mid-level image models for image categorization and cosegmentation. We represent each image class by a dictionary of part detectors that best discriminate that class from the background. We learn category-specific part detectors in a weakly supervised setting in which the training images are only annotated with category labels without part/object location information. We use a latent SVM model regularized using the (Formula presented.) group sparsity norm to learn the part detectors. Starting from a large set of initial parts, the group sparsity regularizer forces the model to jointly select and optimize a set of discriminative part detectors in a max-margin framework. We propose a stochastic version of a proximal algorithm to solve the corresponding optimization problem. We apply the learned part detectors to image classification and cosegmentation, and present extensive comparative experiments with standard benchmarks. © 2016 Springer Science+Business Media New York Source

Liu F.,Xianning University
2011 International Conference on Consumer Electronics, Communications and Networks, CECNet 2011 - Proceedings | Year: 2011

This article describes a design of Digital Control of DC current source based on AVR microcontroller. The system uses the Atmega8 as the main chip and consists of keyboard input, LCD display, I / V conversion, power amplification and other modules. It uses a negative feedback closed-loop control. The MCU can compare real-time the preset value with the measuring results, and adjuste the settings, in order to advance the output precision of the current. The design can achieve the functions of different measurement ranges, adjustable output current, exact step and very small current waviness. It also can display the output preset value and the measuring results by LED at the same. © 2011 IEEE. Source

Cheng Y.,Central China Normal University | Yang H.,Central China Normal University | Cheng Z.,Xianning University | Wu N.,China Ship Development And Design Center
Applied Physics A: Materials Science and Processing | Year: 2011

In this paper, we present a polarization-insensitive metamaterial (MM) absorber which is composed of the dielectric substrate sandwiched with split-ring-cross resonator (SRCR) and continuous metal film. The MM absorber is not limited by the quarter-wavelength thickness and can achieve near-unity absorbance by properly assembling the sandwiched structure. Microwave experiments demonstrate the maximum absorptivity to be about 99% around 10.91 GHz for incident wave with different polarizations. The surface currents distributions of the resonance structure are discussed to look into the resonance mechanism. Importantly, our absorber is only 0.4 mm thick, and numerical simulations confirm that the MM absorber could achieve very high absorptivity at wide angles of incidence for both transverse electric (TE) wave and transverse magnetic (TM) wave. The sandwiched structure is also suitable for designing of a THz and even higher frequency MM absorber, and simulations demonstrate the absorption of 99% at 1.105 THz. © 2010 Springer-Verlag. Source

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