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The potential of subharmonically pumped paramps in monolithic microwave integrated circuits (MMICs) is examined.

This paper investigates both theoretical and implementation-level aspects of switching-feedback control strategies for the development of harmonic oscillators. We use sliding-mode compensation based on various norms of the system state to achieve amplitude control over a wide-tuning range. A 7.6-MHz I/Q LC oscillator is developed and tested. Measurements show that implementation of the proposed switch-based amplitude controller provides accurate amplitude control over the entire frequency tuning range while inducing only a minor phase noise degradation (of less than 2 dBc/Hz). Index Terms--Amplitude control, analog circuits, harmonic distortion, nonlinear systems, sliding-mode control, voltage-controlled oscillator (VCO), wide tuning range.

Visual sensor networks (VSNs) provide surveillance images/video which must be protected from eavesdropping and tampering en route to the base station. In the spirit of sensor networks, we propose a novel paradigm for securing privacy and confidentiality in a distributed manner. Our paradigm is based on the control of dynamical systems, which we show is well suited for VSNs due to its low complexity in terms of processing and communication, while achieving robustness to both unintentional noise and intentional attacks as long as a small subset of nodes are affected. We also present a low complexity algorithm called TANGRAM to demonstrate the feasibility of applying our novel paradigm to VSNs. We present and discuss simulation results of TANGRAM.

All-electric ship power systems include less generation capacity and smaller rotating inertia compared with large power systems. The systems include large portions of nonlinear loads and dynamic loads, which may reduce the stability margin. Moreover, various operational constraints, such as system frequency constraint, motor voltage constraint and dynamic cable constraint, need to be satisfied in operational real time. Further, pulse loads draw very high short-time power in an intermittent way, which may significantly deteriorate the power quality of the system. In this paper, a novel multi-agent system cooperative controller for a medium voltage AC (MVAC) system of all-electric ship power systems is developed to balance load and generation in real time while satisfying system's operational constraints and considering load priorities. The new method coordinates the pulse load and the propulsion load to reduce the impact of pulse load changes on the power quality of all-electric ship power systems. The dynamic behavior of the new method is evaluated using case studies in PSCAD software. [ABSTRACT FROM PUBLISHER]

It is well known that information will play an important role in enhancing emerging smart grid system operation. Therefore, questions naturally arise as to when the increased data-dependence may be considered excessive. Two practical considerations emerge: 1) communications and computational overhead, in which redundant and irrelevant information acquisition and use results in heavy computational burden with limited performance return; and 2) increasing risks of power system disruption due to information delay from communication congestion or cyber attack. One strategy to improve smart grid resilience is to determine the appropriate degree of dependence on cyber information to balance performance with overhead and risk. In this paper, we present a hierarchical cyber-physical multiagent model of smart grid system operation based on flocking theory in the context of the transient stability problem. Through this model, we study strategies that harness a selective degree of cyber technology by leveraging physical couplings. Our formulation enables the identification of large-scale distributed control strategies for robust and resilient power grid operation. We demonstrate the potential performance improvements of our findings on the New England 39-bus power system for case studies involving a variety of system faults and communication delays. [ABSTRACT FROM PUBLISHER]

This paper explores distributed smart grid attack strategies to destabilize power system components using variable structure system theory. Here, an opponent is able to remotely control multiple circuit breakers within a power system, say through data corruption or communication network attack, to destabilize target synchronous generators through application of state-dependent breaker switching. In contrast to attack via a single breaker, the multi-switch case provides additional degrees of freedom that can lead to stealthier and wide-scale cascading failures. We provide a dynamical systems context for formulating distributed multi-switch strategies and execute such attacks on the New England 10-generator 39-bus test system. [ABSTRACT FROM PUBLISHER]

All-electric ship power systems have finite generation and include a large portion of dynamic loads and nonlinear loads relative to the total power capacity. Therefore, the load demand and power generation of the system should be matched in real-time. In this paper, a novel multi-agent system-based real-time load management technique is proposed to optimally determine the switch status of loads in DC zones while satisfying the operating constraints of the system in real-time. The multi-agent system cooperative control protocol is developed based on a proposed reduced-order agent model and artificial potential function of the multi-agent system, which aims to maximize the energized loads in the all-electric ship power system. The cooperative controller aims to cooperatively achieve the group objectives that are difficult to reach by centralized controller. Further, simulation results verify the viability and performance of the proposed technique in PSCAD/EMTDC software. [ABSTRACT FROM PUBLISHER]

Parametric amplifiers are absent today from the majority of electronics applications. This is especially the case for parametric downconverters (PDCs). Coupled with the increasing emphasis on millimeter-wave applications and the cost of transistor scaling, the time may be right to reconsider these circuits. By employing coupled-mode theory, we arrive at a general description of PDCs. Consequently, a simple mixer is proposed that achieves gain at reduced pumping frequencies without resorting to sub-harmonics. The implications of this design for quadrature receiver systems are shown. Fundamental gain and noise limits are derived indicating the ability to operate at sub-5-dB noise figures (NFs) with very low-power requirements. Measurements on an accumulation-mode varactor in 130-nm CMOS technology indicate the necessary pumping and biasing regimes needed to approach these limits. Finally, a compact 30-GHz PDC design with 2-dB NF is discussed. [ABSTRACT FROM AUTHOR]

The design of a screw-type chaotic system in ${\cal R}^3 $ is presented whereby the dynamical equations are constructed using geometric methods that produce a vector field with the desired properties. We utilize piecewise linear and constant dynamics for simplicity; the piecemeal dynamics are combined using switching functions. An analysis of the system shows invariance and the absence of equilibria — implying the existence of limit cycles and strange attractors; a bifurcation diagram confirms the existence of these behavioral modes and that the system undergoes a period-doubling cascade to chaos. We finally present a hardware realization of this system, and oscilloscope traces showing a chaotic system trajectory. [ABSTRACT FROM AUTHOR]

There is a critical need to provide privacy and security assurances for distributed multimedia sensor networking in applications including military surveillance and healthcare monitoring. Such guarantees will enable the widespread adoption of such information systems, leading to largescale societal benefit. To effectively address protection and reliability issues, secure communications and processing must be considered from system inception. Due to the emerging nature of broadband sensor systems, this provides fertile research ground for proposing more paradigm-shifting approaches. This paper discusses issues in designing for security and privacy in distributed multimedia sensor networks. We introduce the Heterogeneous Lightweight Sensornets for Trusted Visual Computing framework for distributed multimedia sensor networks. Protection issues within this architecture are analyzed, leading to the development of open research problems including secure routing in emerging free-space optical sensor networks and distributed privacy for vision-rich sensor networking. Proposed solutions to these problems are presented, demonstrating the necessary interaction among signal processing, networking, and cryptography. [ABSTRACT FROM AUTHOR]

Characteristics of the collective behavior of groups have been studied in diverse disciplines; in this work, we present an approach grounded in robotics. We first specify a model for collective behavior based on a formulation of a multi-agent robotic system. In contrast to some models found in the literature, we do not use stochastic mechanisms to introduce fluctuations. Rather, we present a fully deterministic model where fluctuations emerge due to the complex dynamics of a high-dimensional coupling of dynamical systems. We investigate the emergence of fluctuations in the trajectories of individual agents about the group average trajectory, and present an illustration of the onset of these fluctuations as inter-agent coupling is increased. A selection of behavioral modes are also provided, illustrating the nature of these fluctuations. [ABSTRACT FROM AUTHOR]

Presents the development of a compensation method for continuous-time δ-σ modulators valid for loop filters of arbitrary order. Overview of proposed compensators; Proof of the stabilizing effect of soft-resetting-compensation; Methodology; Results and discussion.

All-electric ship power systems have limited generation and include a large portion of nonlinear loads and dynamic loads relative to the total power capacity. In DC zonal ship power systems, power converter constraints and motor load voltage constraints need to be satisfied in operational real time. Sudden load changes may cause significant frequency oscillations on the AC side of the system. The load dynamics and priorities also need to be considered. Thus, individual loads in the DC zonal system need to be optimally regulated in operational real time to improve the power quality and system level stability. In this paper, a heterogeneous multi-agent system (MAS) framework was developed for a DC zonal system of an all-electric ship power system to achieve dynamic generation and load balancing while satisfying operational constraints as well as considering load priorities. The developed method integrates system dynamics and various operational constraints into MAS and controls individual loads using decentralized cooperative controller. Simulation results on a two-zone notional all-electric ship power system simulated in PSCAD software show the viability and performance of the proposed technique. [ABSTRACT FROM AUTHOR]