Pressure-actuated liquid metal devices are demonstrated for reconfigurable electromagnetic fundamentals at GHz frequencies, including tunable dipole antennas, switchable shielding with 35 dB attenuation, ~30 dB polari...
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Pressure-actuated liquid metal devices are demonstrated for reconfigurable electromagnetic fundamentals at GHz frequencies, including tunable dipole antennas, switchable shielding with 35 dB attenuation, ~30 dB polarizer attenuation, and ~40 degree diffraction from a linear grating. In addition to a wide variety of electromagnetic effects, these devices are further advanced by: being highly physically flexible; in use of non-toxic GaInSn (68.5% Ga, 21.5% In, and 10.0% Sn ) alloy as enabled by a sealed closed system with an acidic vapor background; and non-alloying/corrosion-resistant carbon inks for electrical connection. Collectively, this work addresses a wide variety of electromagnetic fundamentals, and the device construction advances required for real-world applications.
A useful measure is presented for comparison of distinct cryptosystems, including (i) the RSA algorithm, (ii) EIGamal algorithm, (iii) a cryptosystem based on radio background noise (RBN), and (iv) a new cryptosystem ...
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Deadlocks are a rather undesirable phenomenon in flexible manufacturing systems (FMSs). This work, by adding monitors, develops a deadlock prevention policy for FMSs that can be modeled by a class of Petri nets called...
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Deadlocks are a rather undesirable phenomenon in flexible manufacturing systems (FMSs). This work, by adding monitors, develops a deadlock prevention policy for FMSs that can be modeled by a class of Petri nets called α-S 3 PR with ξ-resources. First, an algorithm is given to reduce an S 3 PR via a ξ-resource. Based on it, ξ-resources in α-S 3 PRs are classified into A-ξ-resources and B-ξ-resources. Next, for an α-S 3 PR with only B-ξ-resources, it is proved that a maximally permissive liveness-enforcing supervisor can be designed by M-controlling all the emptied strict minimal siphons (SMSs). For an α-S 3 PR containing A-ξ-resources, a liveness-enforcing supervisor can be designed by iteratively reducing the net via A-ξ-resources and adding the corresponding monitors. Finally, a comprehensive deadlock prevention algorithm for α-S 3 PRs is presented. An FMS example is used to illustrate its application.
Digital design has been growing rapidly during the last years, offering advanced implementation solutions for a diversity of appliances and instruments, integrating different sensors and actuators. This has a great im...
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Digital design has been growing rapidly during the last years, offering advanced implementation solutions for a diversity of appliances and instruments, integrating different sensors and actuators. This has a great impact on embedded automation, where traditional Programmable Logic Controllers (PLCs) have been gradually replaced by high performance Embedded Controllers, Digital Signal Processor (DSP) chips and, more recently, power efficient Field Programmable Gate Arrays (FPGAs). Such new implementation platforms bring together efficient design methodologies, like model-based design and high-level or C level program-based design. In their turn, new design methodologies are accompanied by new design technologies like Intellectual Property (IP) based design and High-Level Synthesis (HLS). This paper presents a design environment that utilizes program-based and model-based design, for the development of PLC applications. Specifically, a tool flow is constructed that supports either the design of new control algorithms or the translation of existing algorithms into C. Then, HLS and FPGA implementation tools are adopted, to implement the selected algorithms as multicore, embedded designs, offering performance improvements and hardware utilization efficiency. Overall, the proposed methodology and underlying tool flow support a novel high productivity prototyping platform for digital control applications, with very promising future extension capabilities.
OFDM is promising for underwater acoustic (UWA) communications due to its potential to combat the large delay spread. However, the performance of the OFDM system is seriously deteriorated by the inter-carrier interfer...
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ISBN:
(纸本)9781479982981
OFDM is promising for underwater acoustic (UWA) communications due to its potential to combat the large delay spread. However, the performance of the OFDM system is seriously deteriorated by the inter-carrier interference (ICI) caused by the transmitter/receiver motion and ocean waves. In this paper, we propose a novel ICI countermeasure. The key idea is to inactivate partial subcarriers according to index modulation and meanwhile transmit signals with opposite polarity on two adjacent active subcarriers for ICI self cancellation. Simulation results validate that the proposed scheme achieves much better bit error rate (BER) performance than many existing schemes in UWA communications.
Auction is believed to be an effective way to solve or relieve the problem of radio spectrum shortage, by dynamically redistributing idle wireless channels of primary users to secondary users. However, to design a pra...
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ISBN:
(纸本)9781450321938
Auction is believed to be an effective way to solve or relieve the problem of radio spectrum shortage, by dynamically redistributing idle wireless channels of primary users to secondary users. However, to design a practical channel auction mechanism, we have to consider five challenges, including strategy-proofness, channel spatial reusability, channel heterogeneity, bid diversity, and social welfare maximization. Unfortunately, none of the existing works fully considered the five design challenges. In this paper, we present the first in-depth study on the problem of dynamic channel redistribution by jointly considering the five design challenges, and present SMASHER, which is a Strategy-proof coMbinatorial Auction mechaniSm for Heterogeneous channel Redistribution. Our analyses show that SMASHER achieves both strategy-proofness and approximately efficient social welfare. Copyright 2013 ACM.
This paper studies semi-global leader-following output consensus of a multi-agent system. Each follower agent in the system, described by a general linear system subject to external disturbances and actuator saturatio...
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This paper studies semi-global leader-following output consensus of a multi-agent system. Each follower agent in the system, described by a general linear system subject to external disturbances and actuator saturation, is to track the leader agent. Conditions on the agent dynamics are identified under which a low gain feedback based linear state control algorithm is constructed for each follower agent such that the leader-following output consensus is achieved when the communication topology among the agents is a directed graph that contains no loop and the leader is globally reachable. In addition, discussions and simulations are also provided for the output consensus in the presence of actuator saturation.
Recently, tag recommendation (TR) has become a very hot research topic in data mining and related areas. However, neither co-occurrence based methods which only use the item-tag matrix nor content based methods which ...
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ISBN:
(纸本)9781577356332
Recently, tag recommendation (TR) has become a very hot research topic in data mining and related areas. However, neither co-occurrence based methods which only use the item-tag matrix nor content based methods which only use the item content information can achieve satisfactory performance in real TR applications. Hence, how to effectively combine the item-tag matrix, item content information, and other auxiliary information into the same recommendation framework is the key challenge for TR. In this paper, we first adapt the collaborative topic regression (CTR) model, which has been successfully applied for article recommendation, to combine both item-tag matrix and item content information for TR. Furthermore, by extending CTR we propose a novel hierarchical Bayesian model, called CTR with social regularization (CTR-SR), to seamlessly integrate the item-tag matrix, item content information, and social networks between items into the same principled model. Experiments on real data demonstrate the effectiveness of our proposed models.
Context-driven decision making is at the top of the Navy's agenda of important concepts to be embedded in future proactive decision support systems for command decision making. There are manifold challenges associ...
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Context-driven decision making is at the top of the Navy's agenda of important concepts to be embedded in future proactive decision support systems for command decision making. There are manifold challenges associated with relaying contextual data in a timely manner to the decision maker. In the counter-smuggling domain, for example, although high value information is accessible, it is dispersed across databases and the decision making team. There are numerous research challenges in integrating this information in an efficient manner to effectively present viable courses of action to a decision making team. In this paper, we propose a decision support tool for counter-smuggling missions modeled as a stochastic control problem of dynamically managing assets to maximize the probability of detecting and interdicting maritime illicit trafficking operations. We additionally propose a method to explain the algorithm behavior to the human decision maker and provide them with interactive controls to develop “what-if” solutions or to constrain solutions to a desired path.
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