Browsing by Author "Wu, Min"
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Item Anti-Collusion Fingerprinting for Multimedia(2002) Trappe, Wade; Wu, Min; Liu, K.J. Ray; ISRDigital fingerprinting is a technique for identifyingusers who might try to use multimedia content for unintendedpurposes, such as redistribution. These fingerprints are typicallyembedded into the content using watermarking techniques that aredesigned to be robust to a variety of attacks. A cost-effectiveattack against such digital fingerprints is collusion, whereseveral differently marked copies of the same content are combinedto disrupt the underlying fingerprints. In this paper, weinvestigate the problem of designing fingerprints that canwithstand collusion and allow for the identification of colluders.We begin by introducing the collusion problem for additiveembedding. We then study the effect that averaging collusion hasupon orthogonal modulation. We introduce an efficient detectionalgorithm for identifying the fingerprints associated with Kcolluders that requires O(K log(n/K)) correlations for agroup of n users. We next develop a fingerprinting scheme basedupon code modulation that does not require as many basis signalsas orthogonal modulation. We propose a new class of codes, calledanti-collusion codes (ACC), which have the property that thecomposition of any subset of K or fewer codevectors is unique.Using this property, we can therefore identify groups of K orfewer colluders. We present a construction of binary-valued ACCunder the logical AND operation that uses the theory ofcombinatorial designs and is suitable for both the on-off keyingand antipodal form of binary code modulation. In order toaccommodate n users, our code construction requires onlyO(sqrt{n}) orthogonal signals for a given number of colluders.We introduce four different detection strategies that can be usedwith our ACC for identifying a suspect set of colluders. Wedemonstrate the performance of our ACC for fingerprintingmultimedia and identifying colluders through experiments usingGaussian signals and real images.This paper has been submitted to IEEE Transactions on Signal Processing Item Coordinated Sensor Deployment for Improving Secure Communications and Sensing Coverage(2005) Mao, Yinian; Wu, Min; Wu, Min; ISRSensor network has a great potential in applications such as habitat monitoring, wildlife tracking, building surveillance, and military combat. The design of a sensor network system involves several important issues, including the sensing coverage, node-to-node or node-to-base-station communications, and the security in information gathering and relay by the sensors. In this paper, we show that the system performance on these aspects depends closely on how the sensors are deployed in the field, and on how the sensor locations can be adjusted after the initial deployment. For static sensor deployment, we investigate the hexagon and square lattice topology and analyze their impact on secure connectivity and sensing coverage. For advanced sensing devices that allow for location adjustment after deployment, we have established a new framework for coordinated updates of sensor locations. We propose two new sensor location updating algorithms, the VFSec and the Weighted Centroid algorithm, to jointly optimize sensing coverage and secure connectivity. Simulation results show that these new algorithms provide superior tradeoff over the existing approaches that do not take security into considerations.Item High-Performance Lithium Metal Batteries Enabled by a Fluorinated Cyclic Ether with a Low Reduction Potential(Wiley, 2023-01-02) Wu, Min; Wang, Zeyi; Zhang, Weiran; Jayawardana, Chamithri; Li, Yue; Chen, Fu; Nan, Bo; Lucht, Brett L.; Wang, ChunshengElectrolyte engineering is crucial for developing high-performance lithium metal batteries (LMB). Here, we synthesized two cosolvents methyl bis(fluorosulfonyl)imide (MFSI) and 3,3,4,4-tetrafluorotetrahydrofuran (TFF) with significantly different reduction potentials and add them into LiFSI-DME electrolytes. The LiFSI/TFF-DME electrolyte gave an average Li Coulombic efficiency (CE) of 99.41 % over 200 cycles, while the average Li CEs for MFSI-based electrolyte is only 98.62 %. Additionally, the TFF-based electrolytes exhibited a more reversible performance than the state-of-the-art fluorinated 1,4-dimethoxylbutane electrolyte in both Li||Cu half-cell and anode-free Cu||LiNi0.8Mn0.1Co0.1O2 full cell. More importantly, the decomposition product from bis(fluorosulfonyl)imide anion could react with ether solvent, which destroyed the SEI, thus decreasing cell performance. These key discoveries provide new insights into the rational design of electrolyte solvents and cosolvents for LMB.