Incremental transmission loss allocation under pool dispatch

Incremental transmission loss analysis has been used for decades, but recent interest in its application to loss allocation calls for new in-depth results. This paper demonstrates that, for incremental methods to be applied correctly in loss allocation, it is first necessary to specify the load distribution and loss supply strategies. Incremental loss allocation among bus power injections is shown to be arbitrary and, therefore, open to challenge as discriminatory. Loss allocation is possible among incremental loads and/or generators, but the proportion of the total losses assigned to either one is arbitrary. Unique, nonarbitrary incremental loss allocations are however possible among the "equivalent" incremental bilateral exchanges between generators and loads. From these basic components it is possible then to calculate the allocation among generators or loads in any specified proportion. The main results, although developed initially for small increments, are extended to large variations. Finally, a general incremental loss allocation algorithm is developed and tested     

Simulation of magnetic component models in electric circuitsincluding dynamic thermal effects

It is essential in the simulation of power electronics applications to model magnetic components accurately. In addition to modeling the nonlinear hysteresis behavior, eddy currents and winding losses must be included to provide a realistic model. In practice the losses in magnetic components give rise to significant temperature increases which can lead to major changes in the component behavior. In this paper a model of magnetic components is presented which integrates a nonlinear model of hysteresis, electro-magnetic windings and thermal behavior in a single model for use in circuit simulation of power electronics systems. Measurements and simulations are presented which demonstrate the accuracy of the approach for the electrical, magnetic and thermal domains across a variety of operating conditions, including static thermal conditions and dynamic self heating     

Terahertz/optical mixing in symmetric semiconductor quantum wells embedded in optical microcavities

A quantum well (QW) in the simultaneous presence of a terahertz field polarized in the growth direction and an incident optical field near an excitonic resonance results in substantial frequency mixing between the terahertz and optical fields. In particular, a response at new frequencies given by the input optical frequency plus or minus multiples of the terahertz frequency occurs-the terahertz sidebands. In a symmetric QW, the dominant contribution to terahertz-sideband formation is the high-frequency modulation of the overlap integral of the relevant conduction- and valence-subband envelope functions that determine the strength of the interband dipole moment. terahertz-sideband generation is shown to be strongly enhanced in a high quality-factor optical microcavity. Numerical values of the reflected intensity into the first terahertz sideband normalized with respect to the reflected intensity at the fundamental as large as /spl sim/10% are estimated. This suggests that terahertz-sideband generation in semiconductor microcavities is a promising option worthy of exploration for wavelength conversion for wavelength-division multiplexing applications.     

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In this paper, the authors present the results of experiments which clearly demonstrate a technical basis confirming that the carrier frequency harmonics data can be used for diagnostics relative to motor stator insulation degradation.     

Homogeneity characterisation of sintered (U,Gd)O2 pellets by X-ray diffraction

(U,Gd)O₂ sintered pellets are fabricated by different methods. The homogeneity characterisation of the Gd content seems to be necessary for a production control to qualify the process and the final product obtained. In this paper, we propose an analysis of the X-ray diffraction powder patterns through the Rietveld method, in which the differences between the experimental and the calculated data proposed from a crystalline structure model are evaluated. This result allows us to determine the cell parameters, that can be correlated with the Gd concentration, and the existence of other phases with different Gd contents.     

On the nonuniformity of a capillary flow

It is established that the capillary rise of a liquid has an oscillatory character, in contrast to the commonly accepted opinion that a vertical capillary is filled at a monotonically varying velocity. The value of the tangential shear stress arising in an ascending liquid is evaluated for ethyl alcohol and distilled water.     

An Adaptive Recipe Implementation in Case‐Based Formalism for Abnormal Condition Management

This paper deals with accurate recipe implementation for abnormal condition management in a batch process using a case‐based reasoning (CBR) approach. A set of new problems can be solved by reusing proven process solutions. The proposed system integrates quantitative and qualitative parameters for adaptation of cases. A novel methodology to generate accurate recipes and to adapt to the processes is introduced during normal and abnormal conditions. In particular, the differences between current conditions and the references (recipes) should be managed to prevent any hazardous conditions arising. The processes are evaluated using their similarity to the past cases. This intelligent approach distinguishes plausible cases, generates accurate recipes, and adapts to new situations. The aim is to use the offline historical process data and safety related information in order to propose changes and adjustments in the processes.     

Immobilization and activation of vanadium(III) and titanium(III) single‐site catalysts for ethylene polymerization using MgCl2‐based supports

Significant increases in the activity of vanadium(III) amidinate catalysts for ethylene polymerization have been obtained by immobilization on a MgCl₂‐based support prepared by reaction of AlEt₃ with a MgCl₂/ethanol adduct. Catalyst immobilization and activation on this type of support prevents the rapid decay in activity observed under homogeneous polymerization conditions with unsupported catalysts. Stable polymerization activity is also observed with analogous titanium(III) complexes. Polyethylene with narrow molecular weight distribution and spherical particle morphology is obtained without reactor fouling. Copyright © 2005 Society of Chemical Industry