36,524 research outputs found

    Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

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    The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented

    Switched capacitor networks : a novel prewarping procedure

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    Bibliography: leaves 152-157.Novel methods for prewarping filter specifications prior to realization. in Switched Capacitor (SC) form are presented. These allow the design of arbitrary response requirements, exhibiting a low amount of error that normally results from the frequency warping associated with sampled-data networks. Adjustment is applied to the pole and zero locations of a reference filter, using three distinct approaches (Center frequency "CF", Selectivity "S" and Complex Mapping "CM" pole/zero prewarping), developed for both the Lossless Discrete Integrator (LOI) and Bilinear (Bil) analog to digital transformations. The derivation of the prewarping expressions is explained with reference to these mappings, and the effect they have on the apparent pole and zero locations of an SC filter realization

    PID control system analysis, design, and technology

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    Designing and tuning a proportional-integral-derivative (PID) controller appears to be conceptually intuitive, but can be hard in practice, if multiple (and often conflicting) objectives such as short transient and high stability are to be achieved. Usually, initial designs obtained by all means need to be adjusted repeatedly through computer simulations until the closed-loop system performs or compromises as desired. This stimulates the development of "intelligent" tools that can assist engineers to achieve the best overall PID control for the entire operating envelope. This development has further led to the incorporation of some advanced tuning algorithms into PID hardware modules. Corresponding to these developments, this paper presents a modern overview of functionalities and tuning methods in patents, software packages and commercial hardware modules. It is seen that many PID variants have been developed in order to improve transient performance, but standardising and modularising PID control are desired, although challenging. The inclusion of system identification and "intelligent" techniques in software based PID systems helps automate the entire design and tuning process to a useful degree. This should also assist future development of "plug-and-play" PID controllers that are widely applicable and can be set up easily and operate optimally for enhanced productivity, improved quality and reduced maintenance requirements

    Modeling and Analysis of Power Processing Systems (MAPPS), initial phase 2

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    The overall objective of the program is to provide the engineering tools to reduce the analysis, design, and development effort, and thus the cost, in achieving the required performances for switching regulators and dc-dc converter systems. The program was both tutorial and application oriented. Various analytical methods were described in detail and supplemented with examples, and those with standardization appeals were reduced into computer-based subprograms. Major program efforts included those concerning small and large signal control-dependent performance analysis and simulation, control circuit design, power circuit design and optimization, system configuration study, and system performance simulation. Techniques including discrete time domain, conventional frequency domain, Lagrange multiplier, nonlinear programming, and control design synthesis were employed in these efforts. To enhance interactive conversation between the modeling and analysis subprograms and the user, a working prototype of the Data Management Program was also developed to facilitate expansion as future subprogram capabilities increase

    On-chip evaluation of oscillation-based-test output signals for switched-capacitor circuits

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    This work presents a simple and low-cost method for on-chip evaluation of test signals coming from the application of the Oscillation-Based-Test (OBT) technique. This method extracts the main test signal features (amplitude, frequency and DC level) in the digital domain requiring just a very simple and robust circuitry. Experimental results obtained from an integrated chip demonstrate the feasibility of the approac
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