Fundamental Design Features Research Articles

Experience with PJM market operation, system design, and implementation

This paper outlines the fundamental features of the PJM day-ahead energy market and real-time energy market. The Day-ahead market is based on a voluntary least-cost security constrained unit commitment and dispatch with several fundamental design features that ensure the market is robust and competitive. This market offers market participants the option to lock in energy and transportation charges at binding day-ahead prices. The flexibility of the day-ahead market rules provide all participants with equal access to the day-ahead market through consistent price signals and by providing all participants with the ability to submit virtual demand bids and virtual supply offers. These mechanisms promote liquidity in the markets. Economic incentives drive the convergence of the day-ahead and real-time market prices. The real-time energy market is based on security-constrained economic dispatch and is cleared based on the actual system operating conditions. The LMP-based markets support reliable grid operations through efficient price signals.

Transcriptional Networks and Their Relatives

Living cells are the product of gene expression programs involving regulated transcription of thousands of genes. Lee et al. used immunoprecipitation and microarray studies to build a global analysis of transcriptional regulatory networks in Saccharomyces cerevisiae . Patterns observed were characterized as motifs that were then combined by an automatic process into a network structure. Such transcriptional regulation represents a network of interactions, and similar networks underlie apparently unrelated systems, such as food webs and electronic circuits. To examine their fundamental design features, Milo et al. (see the Perspective by Oltvai and Barabási) looked at local organizing principles of networks, expressed as motifs of how different interactors are joined, that occurred at more than random frequencies. Motifs shared by food webs had features that were not shared by transcription networks from yeast and from Escherichia coli or by electronic circuits, although similarities were seen in information-processing circuits. T. I. Lee, N. J. Rinaldi, F. Robert, D. T. Odom, Z. Bar-Joseph, G. K. Gerber, N. M. Hannett, C. T. Harbison, C. M. Thompson, I. Simon, J. Zeitlinger, E. G. Jennings, H, L. Murray, D. B. Gordon, B. Ren, J. J. Wyrick, J.-B. Tagne, T. L. Volkert, E. Fraenkel, D. K. Gifford, R. A. Young, Transcriptional regulatory networks in Saccharomyces cerevisiae . Science 298 , 799-804 (2002). [Abstract] [Full Text] R. Milo, S. Shen-Orr, S. Itzkovitz, N. Kashtan, D. Chklovskii, U. Alon, Network motifs: Simple building blocks of complex networks. Science 298 , 824-827 (2002). [Abstract] [Full Text] Z. N. Oltvai, A.-L. Barabási, Life's complexity pyramid. Science 298 , 763-764 (2002). [Summary] [Full Text]

PROFILE: Urban Stream Rehabilitation: A Design and Construction Case Study.

/ This paper describes the fundamental design features, and construction methods and sequence, of a rehabilitation project on a small suburban creek in Moscow, Idaho, USA. A meandering channel pattern was reestablished for approximately 280 m of straightened, dredged channel, a new floodplain was excavated, and the new riparian zone was replanted. The new stream channel was sized to accommodate an estimated natural bankfull discharge ( approximately 5.6 cms), and floodplain design attempted to match the conveyance of the old enlarged channel (14-20 cms). The project was coordinated by a local nonprofit environmental organization, and the design and construction were tailored to donated materials and a largely volunteer labor force. A high-magnitude flood event (ca. 50-year recurrence interval) six months after construction had no significant impact on the newly constructed channel and revetments, but underscored the need for important detailing of the structures. The use of volunteer labor, while entailing certain benefits, complicates project planning and construction. The most general lesson learned from this project is that sponsoring agencies and clients need to be informed of the many steps and sequencing of properly constructed, complex stream rehabilitation projects as well as the high time and cost requirements for these tasks. KEY WORDS: Stream corridor restoration; Channel design; Streambank revetments

Studying the determinants of exposure: a review of methods.

To better understand where, when, and how to control occupational exposures, it is vital that hygienists understand the factors that contribute to elevated or reduced exposure levels. Over the last two decades a burgeoning literature examining the determinants of exposure has developed, yet to date the methods used in this regard have rarely been summarized in texts or elsewhere. The purpose of this article is to provide an overview of the techniques used to study the predictors of workplace exposures. Both experimental and observational studies are examined, and the advantages and limitations of each are discussed. Fundamental study design features are reviewed. These include the selection and measurement of factors potentially related to exposure, as well as the measurement of exposure itself. Decisions reached by investigators in selecting the number of sites and workers, the number of repeated observations per worker, and the duration of sampling are discussed. Also examined are issues that commonly arise in the course of data analysis of exposure determinants. These include transformation of exposure variables, correlation of predictor variables, empirical model building, and interpretation of results. Finally, methods employed to evaluate the validity of findings are summarized.

Characteristics of designing, planning, and technology of constructing structures for developing Arctic fields

The Russian and world offshore oil and gas industry has gained considerable experience in developing the shelf of seas with a temperate climate, but it does not have a developed technology and all necessary tested technical means for large-scale organization of exploration and exploitation in waters of arctic seas. Therefore, at present engineers are intensely searching for optimal designs for creating ice-resistant structures able to operate under harsh arctic conditions and have high reliability and long life. For convenience of analysis of the design features of offshore oil- and gas-field hydrotechnical engineering structures (OOGSs), it is necessary to classify them primarily according to the technological tasks set before them. It is known that the design of OOGSs consists of such components as the platform superstructure (PS), support part (SP), and foundation each of which has fundamental design features. The hydrometeorological factors are the main ones when determining the design features for the support part of OOGSs. Geological-engineering factors affect the selection of the type of OOGSs and are the determining factors of the design of the foundation of the structures. The results of analyzing the problems make it possible to single out the primary scientific-technical problems aimed at the accomplishmentmore » of tasks related to the creation of OOGSs for developing hydrocarbon resources of the arctic shelf.« less

A suitable generalized predictive adaptive controller case study: Control of a flexible arm

This paper presents an adaptive control case study involving a flexible arm. The underlying control design consists in a judicious combination of the pole placement concept and the generalized predictive control design. The former allows one to incorporate a suitable tracking capability while the latter is more advisable from practical use point of view. A particular emphasis is put on the fundamental design features of the adaptive controller, namely the tracking capability, the adaptation alertness and the robustness with respect to reduced order modelling.

Partial state model reference adaptive control of a rapid thermal processor

AbstractThe temperature control problem in a rapid thermal processor is addressed using first a conventional PID controller and then a partial state model reference adaptive controller derived via the long‐range predictive control and linear quadratic control approaches. These two algorithms are shown to provide such fundamental design features as offset‐free disturbance rejection and stability robustness with respect to unmodelled and time‐varying dynamics.

Tunnelling using earth pressure balance machines for the boulav spine sewers of the greater Cairo wastewater project

Abstract The paper “Bentonite Tunnelling for the Greater Cairo Wastewater Project” (Flint and Foreman 1992) referred to the proposed use of Earth Pressure Balance Machines (EPBM) for constructing the 6.5 km of tunnels for the Boulac Spine Branch Sewer of the project. In early 1991, tunnelling with the two EPBMs was just about to start, with a programmed operation period of approximately one-and-a-half years. Since then, 6.2 km of 2.87-m and 2.20-m internal-diameter tunnels have been driven by the two EPBMs. This paper describes the fundamental design features of the Boulac Spine Sewer, the operation of the EPBMs and their performance, and the special segments developed for use with these machines. It also considers the various settlement effects recorded in the highly concentrated residential areas of the Boulac District of Cairo.

Radiation monitoring, environmental and health physics aspects during the first JET tritium experiment

The first JET tritium experiment [1] was performed with no radiological incidents, minimal radiation exposure to JET personnel and controlled aerial discharges of tritium to the environment well within daily release limits derived from the discharge Authorisation. Most of the radiological protection measures are fundamental design features of the machine and its buildings. These have been in place for many years as JET is intended for protracted tritium operations. They all performed well and confirmed not only their basic design but also minor areas where enhancements had been thought necessary. Special additional equipment was necessary to perform this limited experiment and they were all designed and operated to the same criteria of safety and radiological protection, taking into account the extent of the experimental programme. The range of radiological protection measures implemented and their performance are described in the paper.

A novel family of traction fluids deriving from molecular design

AbstractAn investigation has been undertaken into the fundamental molecular design features that may be seen to correlate with high traction coefficients of lubricants operating under elastohydrodynamic conditions. With the assistance of computer‐aided molecular mechanics modelling, a novel family of fluids has been designed which display excellent tractional performance. Prospects for the further development of these modelling techniques and also the practical usage of the designed fluids are discussed.

Neutral-Carrier-Based Ion-Selective Microelectrodes Design and Application

At present, neutral-carrier- and ¡on-exchanger-based ion-selective liquid membrane microelectrodes are available for the measurement of H+, Li+, Na+, K+, Mg2+, Ca2+, NH4+ and CI-. Fundamental aspects, design features and limitations of microelectrodes are discussed and examples for their application in physiology are given. The most important characteristics are summarized in view of intra- and extracellular physiological measurements. The selectivity coefficients KijPol with respect to the most common ions are compared to calculated values Kij,maxPol, required for measurements in intra- and extracellular samples without significant interference. For intracellular microelectrode studies, these required values are fully met for H+, K+, Mg2+, Ca2+ and CI-, while in the case of extracellular measurements H+, Na+, K+ and Ca2+ can be assayed adequately.

On the Applicability of Adaptive Control

In the last decade there has been a growing awareness that adaptive control can produce improved performance in real application, mainly as a result of considerable advances in the understanding of adaptive control theory as well as in the computer technology. In this paper the authors aim at providing practical implications of recent results in robustness of adaptive control theory. The fundamental design features as stability robustness, adaption alertness, offset-free performance, implementation simplicity and control system integrity will be emphasized. Simulation studies involving a realistic mathematical model of an electrical furnace are given to highlight the applicability of the involved adaptive controllers.

Thermal Process Robust Adaptive Control: An Experimental Evaluation

There has been a growing awareness over the last decade that adaptive control can produce improved performance in real application, mainly as a result of considerable advances in the understanding of adaptive control theory as well as in the computer technology. Many industrial feasibility studies have been performed and several adaptive controllers are available on the market. In this paper, the authors aim at investigating recent results in the robustness of adaptive control theory from an applicability perspective. A receding-horizon optimal control law is combined with a robust parameter estimator to provide practical adaptive control algorithms. The latter are evaluated by application to temperature control problems, involved in an electric furnace and an extrusion process. Particular emphasis is put on those fundamental design features as stability robustness, offset-free performance, adaptation alertness, control system integrity and implementation simplicity.

Foundations of extensional viscometry part II: Essentials as to design and analysis of hose viscometers

After a historical survey on the evolution of extensional viscometry, two novel types of extensional viscometers are proposed under the designations closed-end and open-end hose viscometer. The hose, which forms an elastically extensible cover of a prolate circular cylinder shape, is to hold an incompressible fluid specimen for investigation, especially under forced oscillations. The measurement of the first type concerns the axial force of the specimen in a thin-walled hose; the measurement of the second type concerns the radial traction of the specimen in a thick-walled hose. Fundamental design features and a mathematical treatment under ideal conditions are set forth for eventually showing how to unroll an informative (though expensive) program of viscometry on the base of harmonic Fourier analysis. In an appendix, the ascertainment of material coefficients is exemplified on specific constitutive assumptions so as to suggest analogously handling other instances on demand.