We describe a method to estimate the capacity limit of fiber-optic communication systems (or ?fiber channels?) based on information theory. This paper is divided into two parts. Part 1 reviews fundamental concepts of digital communications and information theory. We treat digitization and modulation followed by information theory for channels both without and with memory. We provide explicit relationships between the commonly used signal-to-noise ratio and the optical signal-to-noise ratio. We further evaluate the performance of modulation constellations such as quadrature-amplitude modulation, combinations of amplitude-shift keying and phase-shift keying, exotic constellations, and concentric rings for an additive white Gaussian noise channel using coherent detection. Part 2 is devoted specifically to the "fiber channel.'' We review the physical phenomena present in transmission over optical fiber networks, including sources of noise, the need for optical filtering in optically-routed networks, and, most critically, the presence of fiber Kerr nonlinearity. We describe various transmission scenarios and impairment mitigation techniques, and define a fiber channel deemed to be the most relevant for communication over optically-routed networks. We proceed to evaluate a capacity limit estimate for this fiber channel using ring constellations. Several scenarios are considered, including uniform and optimized ring constellations, different fiber dispersion maps, and varying transmission distances. We further present evidences that point to the physical origin of the fiber capacity limitations and provide a comparison of recent record experiments with our capacity limit estimation.

Capacity Limits of Optical Fiber Networks

Summary form only given, as follows. This paper presents a particle swarm optimization (PSO) for reactive power and voltage control (volt/VAr control: VVC) considering voltage security assessment (VSA). VVC can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The proposed method expands the original PSO to handle a MINLP and determines an online VVC strategy with continuous and discrete control variables such as automatic voltage regulator (AVR) operating values of generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of reactive power compensation equipment. The method considers voltage security using a continuation power now and a contingency analysis technique. The feasibility of the proposed method is demonstrated and compared with reactive tabu search (RTS) and the enumeration method on practical power system models with promising results.

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A particle swarm optimization for reactive power and voltage control considering voltage security assessment

(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

http://www.intelligence.tuc.gr/~petrakis/publications/mape02.pdf

A survey on industrial vision systems, applications and tools

The phenomena occurring in semiconductor lasers due to weak external optical feedback are reviewed, including mode hopping and related mode-hopping noise, linewidth narrowing and broadening, and the transition to the coherence collapse regime. Guidelines are given for designing semiconductor lasers, both edge emitters and VCSEL's, with high endurance against external optical feedback. >

External optical feedback phenomena in semiconductor lasers

Stable phase locking of an electrically pumped vertical cavity surface-emitting semiconductor laser (VCSEL) was demonstrated experimentally by injecting light from an edge-emitting master laser into the slave laser VCSEL cavity within a large detuning range (/spl sim/80 GHz). By varying the injected power and frequency detuning, a variety of interesting nonlinear behavior was observed. A theoretical model based on two-field rate equations is presented and compared with experiment, showing good agreement.

Injection locking dynamics of vertical cavity semiconductor lasers under conventional and phase conjugate injection

Experimental and theoretical studies of coherence collapse in GaAs/AlGaAs laser diodes with weak optical feedback show two distinct routes to chaos. In each case we observe undamped relaxation oscillations, then external cavity mode beating, and finally coherence collapse. When there is frequency locking between the relaxation oscillations and external cavity modes, a period doubling sequence is followed, otherwise the route to chaos is via quasiperiodicity. >

Detailed analysis of coherence collapse in semiconductor lasers

A sequence of BCU classifiers for online dynamic contingency screening is developed and their theoretical basis is provided. The design objective of the BCU classifiers is to ensure that unstable (single-swing or multiswing) contingencies be completely captured and that the number of contingencies needed for further analysis be significantly reduced. An architecture for online dynamic security assessments consisting of the BCU classifiers and an online transient stability (time-domain) simulation program is presented. The effectiveness of the developed BCU classifiers and proposed architecture is evaluated with very promising results using 7120 contingencies on a 50-generator, 145-bus power system and a 202-generator, 1293-bus real power system data.

Development of BCU classifiers for on-line dynamic contingency screening of electric power systems

Dynamical methods for obtaining the global optimal solution of general optimization problems having closed form or black box objective functions, including the steps of first finding, in a deterministic manner, one local optimal solution starting from an initial point, and then finding another local optimal solution starting from the previously found one until all the local optimal solutions starting from any initial point are found, and then finding from said points the global optimal solution

Dynamical methods for solving large-scale discrete and continuous optimization problems

The P-V Curve, Q-V Curve, or P-Q-V Curve have been widely used to analyze power system behaviors under varying loading conditions. These curves have been generated under the condition that tire constant P-Q load component of a bus (or a collection of buses) varies, with the constant current load and constant impedance load being kept indeed "constant". As such, the physical meaning of these curves can be easily explained. Motivated by the facts that load models have profound impacts on power system behaviors and that the nonlinear load model ZIP-model is popular in modeling nonlinear behaviors of loads, this paper proposes a new class of curves, called ZIP-V curves, to better trace power system steady-state stationary behavior due to load and generation variations. The ZIP-V curves encompass the traditional P-V, Q-V, P-Q-V curves (constant P-Q load), I-V curve (constant current load), Z-V curve (constant impedance load), or generalized curves such as IP-V (constant current and constant power load), ZP-V (constant impedance and constant power load) or IZ-V (constant current and constant impedance load) curve when the values of corresponding components are kept constant. A tool based on the continuation power flow (CPFLOW) method useful for generating the ZIP-V curves is developed and its application to generate ZIP-V curves of a 4561-bus interconnected power system is illustrated.

Hua Li

Papers

Injection locking dynamics of vertical cavity semiconductor lasers under conventional and phase conjugate injection

Detailed analysis of coherence collapse in semiconductor lasers

Development of BCU classifiers for on-line dynamic contingency screening of electric power systems

Dynamical methods for solving large-scale discrete and continuous optimization problems

The generation of ZIP-V curves for tracing power system steady state stationary behavior due to load and generation variations