A series active power filter based on a sinusoidalcurrent-controlled voltage-source inverter

A series active power filter working as a sinusoidal current source, in-phase with the mains voltage, has been developed and tested. The amplitude of the fundamental current in the series filter is controlled through the error signal generated between the load voltage and a pre-established reference. The control allows an effective correction of power factor, harmonic distortion and load voltage regulation. Compared with previous methods of control developed for series active filters, this method is simpler to implement because it is only required to generate a sinusoidal current, in-phase with the mains voltage, the amplitude of which is controlled through the error in the load voltage. The proposed system has been studied analytically and tested using computer simulations and experiments. In the experiments, it has been verified that the filter keeps the line current almost sinusoidal and in-phase with the line voltage supply. It also responds very quickly under sudden changes in load conditions, reaching its steady-state in about two cycles of the fundamental     

Reactive Power Compensation Technologies: State-of-the-Art Review

This paper presents an overview of the state of the art in reactive power compensation technologies. The principles of operation, design characteristics and application examples of Var compensators implemented with thyristors and self-commutated converters are presented. Static Var generators are used to improve voltage regulation, stability, and power factor in ac transmission and distribution systems. Examples obtained from relevant applications describing the use of reactive power compensators implemented with new static Var technologies are also described.     

High bit rate digital subscriber line echo cancellation

The authors explore the issues of complexity, precision, and dynamic range and practical implementation issues such as nonlinearities in high bit rate digital subscriber line (HDSL) echo cancelers. The approach taken is to study these issues analytically using computer simulations, and then to verify simulation results with laboratory prototyping. One of the objectives was to determine whether HDSL echo cancellation will be practical and cost effective within the next several years, consistent with the desire to develop and deploy a repeaterless T1 capability by 1993. Thus, attention is given to practical design issues     

Improvement options for a former water-driven-mill building now used as a theatre

After investigating the financial feasibility (and so abandoning the idea) of providing self-generated electricity using hydro-power, it was recommended that the top priority should be the direct connection of an electricity supply, from the mains grid to the building; this would cost £8800. Thereby, the theatre would receive a relatively unrestricted supply of electricity at cheaper unit tariffs. This improvement should be followed by the most urgent repairs being carried out to the building fabric, at an estimated cost of £6990. These repairs are necessary to ensure the continued integrity of the building's structure, thereby inhibiting the on-going deterioration.

The energy and financial appraisal also suggested a priority listing of overall improvements to the building in order to achieve a significant, economically justifiable reduction in energy demand; the recommended options are estimated to cost in total £39819. However, the capital cost of such an upgrading would only be recouped, and the theatre achieve a sustainable future, if the building were to be used more intensively and for a wider range of activities than at present in order to increase its revenue significantly.

All prices as stated are those at August 1991.     

A connectionist implementation of the theory of planned behavior: Association of beliefs with exercise intention.

The theory of planned behavior suggests attitudes are a product of salient beliefs. This study examined whether aggregating salient beliefs was plausible within a more biologically centered information-processing environment. A neural network was used to examine associations among beliefs relating to exercise intention. Data on intentions and behavioral, normative, and control beliefs from 114 respondents were used to train (by error backpropagation) a neural network to associate beliefs with intention. The R2 between the network's estimated and self-reported intention was .66. The network's representation comprised 6 belief profiles associated with high, moderate, or low behavioral intention. The neural network accommodated complex relationships among beliefs and belief-intention associations and indicated how high-level constructs such as attitudes may be viewed as the best fit (compromise state) between aroused beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preview benefit and parafoveal-on-foveal effects from word n + 2.

Using the gaze-contingent boundary paradigm with the boundary placed after word n, the experiment manipulated preview of word n + 2 for fixations on word n. There was no preview benefit for 1st-pass reading on word n + 2, replicating the results of K. Rayner, B. J. Juhasz, and S. J. Brown (2007), but there was a preview benefit on the 3-letter word n + 1, that is, after the boundary but before word n + 2. Additionally, both word n + 1 and word n + 2 exhibited parafoveal-on-foveal effects on word n. Thus, during a fixation on word n and given a short word n + 1, some information is extracted from word n + 2, supporting the hypothesis of distributed processing in the perceptual span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of linguistic structure on children's ability to isolate initial consonants.

In 4 experiments, preschoolers and kindergartners were asked to pronounce the initial consonants of spoken words. Children performed better on short words, such as bay, than on long words, such as bonus. Words with initial consonant clusters, such as brow, were more difficult for the children than words without initial consonant clusters, such as bar. A consonant cluster at the end of the word did not harm performance. Children did relatively well on words like suppose, for which the word's 1st syllable, /s/, constitutes a correct answer on the initial consonant isolation task. Children did more poorly on words like satin, for which this was not the case. Thus, the linguistic structure of a word affects children's ability to isolate the initial consonant. Implications for the design of phonemic awareness instruction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Managing watershed resources

Watersheds, as integrated land and water systems, have proved difficult to manage successfully. This is in part due to the complexities of accommodating different groups of users and making use of multiple resources in spatially large areas. The paper argues, however, that watersheds have a natural physical and economic logic as a unit of analysis. As a bridge between microlevel analysis of individual farmers or economic units and a regional or sectoral approach, the watershed, when analyzed in an integrated, multi-disciplinary manner, yields useful policy results for improved management of land and water resources. Economic analysis plays a key role in this analysis. Integrated analysis, however, does not mean integrated implementation. Existing systems of social and government organization must be used to implement the chosen policies. This is a difficult, but essential step and may require the use of government fiscal and price policies to harmonize social and private goals.The views expressed in this paper are those of the author, who is Research Associate with the East-West Environment and Policy Institute, Honolulu, Hawaii. Parts of this paper draw on Dixon [5], prepared for the Economic Development Institute of the World Bank.