bluuebunny/crossref_metadata_2025 huggingface dataset:
A POSTERIORI ANALYSIS OF A PENALTY METHOD AND APPLICATION TO THE STOKES PROBLEM
Authors: BERNARDI C. , GIRAULT V. , HECHT F.
Published: November 2003

We derive an a posteriori error estimate for an abstract saddle-point problem when a penalty term is added to stabilize the variational formulation, the aim being to optimize the choice of the penalty parameter. As an application, we consider a discretization of the Stokes problem obtained by combining the penalty technique and the finite element method, we perform its a posteriori analysis in a detailed way and present some numerical experiments on adaptive meshes which are in good agreement with the results of the analysis and confirm its interest.
STABILITY OF SHEAR BANDS IN AN ELASTOPLASTIC MODEL FOR GRANULAR FLOW: THE ROLE OF DISCRETENESS
Authors: SHEARER MICHAEL , SCHAEFFER DAVID G. , WITELSKI THOMAS P.
Published: November 2003

Continuum models for granular flow generally give rise to systems of nonlinear partial differential equations that are linearly ill-posed. In this paper we introduce discreteness into an elastoplasticity model for granular flow by approximating spatial derivatives with finite differences. The resulting ordinary differential equations have bounded solutions for all time, a consequence of both discreteness and nonlinearity.

We study how the large-time behavior of solutions in this model depends on an elastic shear modulus ℰ. For large and moderate values of ℰ, the model has stable steady-state solutions with uniform shearing except for one shear band; almost all solutions tend to one of these as t→∞. However, when ℰ becomes sufficiently small, the single-shear-band solutions lose stability through a Hopf bifurcation. The value of ℰ at the bifurcation point is proportional to the ratio of the mesh size to the macroscopic length scale. These conclusions are established analytically through a careful estimation of the eigenvalues. In numerical simulations we find that: (i) after stability is lost, time-periodic solutions appear, containing both elastic and plastic waves, and (ii) the bifurcation diagram representing these solutions exhibits bi-stability.
PROGRESS IN THE PHYSICS OF MASSIVE NEUTRINOS
Authors: BARGER V. , MARFATIA D. , WHISNANT K.
Published: November 2003

The current status of the physics of massive neutrinos is reviewed with a forward-looking emphasis. The article begins with the general phenomenology of neutrino oscillations in vacuum and matter and documents the experimental evidence for oscillations of solar, reactor, atmospheric and accelerator neutrinos. Both active and sterile oscillation possibilities are considered. The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae, highest energy cosmic rays) on neutrino observables and vice versa, is evaluated. The predictions of grand unified, radiative and other models of neutrino mass are discussed. Ways of determining the unknown parameters of three-neutrino oscillations are assessed, taking into account eight-fold degeneracies in parameters that yield the same oscillation probabilities, as well as ways to determine the absolute neutrino mass scale (from beta-decay, neutrinoless double-beta decay, large scale structure and Z-bursts). Critical unknowns at present are the amplitude of νμ→νeoscillations and the hierarchy of the neutrino mass spectrum; the detection of CP violation in the neutrino sector depends on these and on an unknown phase. The estimated neutrino parameter sensitivities at future facilities (reactors, superbeams, neutrino factories) are given. The overall agenda of a future neutrino physics program to construct a bottom-up understanding of the lepton sector is presented.
PARTICLE MULTIPLICITIES AND THERMALIZATION IN HIGH ENERGY COLLISIONS
Authors: HORMUZDIAR JAMES , HSU STEPHEN D. H. , MAHLON GREGORY
Published: November 2003

We investigate the conditions under which particle multiplicities in high energy collisions are Boltzmann distributed, as is the case for hadron production in e+e-, pp, [Formula: see text] and heavy ion collisions. We show that the apparent temperature governing this distribution does not necessarily imply equilibrium (thermal or chemical) in the usual sense. We discuss an explicit example using tree level amplitudes for N photon production in which a Boltzmann-like distribution is obtained without any equilibration. We argue that the failure of statistical techniques based on free particle ensembles may provide a signal for collective phenomena (such as large shifts in masses and widths of resonances) related to the QCD phase transition.
κ-DEFORMED STATISTICS AND THE FORMATION OF A QUARK-GLUON PLASMA
Authors: TEWELDEBERHAN A. M. , MILLER H. G. , TEGEN R.
Published: November 2003

The effect of the non-extensive form of statistical mechanics proposed by Tsallis on the formation of a quark-gluon plasma (QGP) has been recently investigated in Ref. 1. The results show that for small deviations (≈ 10%) from Boltzmann–Gibbs (BG) statistics in the QGP phase, the critical temperature for the formation of a QGP does not change substantially for a large variation of the chemical potential. In the present paper we use the extensive κ-deformed statistical mechanics constructed by Kaniadakis to represent the constituents of the QGP and compare the results with Ref. 1.
RELATIVISTIC DESCRIPTION OF NUCLEAR MATTER IN HARTREE–FOCK APPROXIMATION USING A GENERALIZED HYBRID DERIVATIVE COUPLING
Authors: MITRA PARNA , MALAKAR BINAY , GANGOPADHYAY G.
Published: November 2003

The effect of the exchange terms in nucleon-nucleon interaction is studied for nuclear matter and neutron matter in the framework of the hybrid derivative coupling model. Pseudovector coupling between the pion and the nucleon and both vector and tensor couplings between the rho-meson and the nucleon have been included. A reduced value of the effective nucleon mass is obtained in nuclear matter as a result of the inclusion of the exchange terms. The rho-meson coupling constant obtained from meson exchange theories can be used to get a reasonable value of symmetry energy. The maximum limit of the neutron star mass obtained in this work is more than twice the solar mass. This rather high limit points to the inadequacy of the present Lagrangian at such a high density as it is restricted only to nucleonic degrees of freedom.
ISOSPIN DEPENDENCE OF GROUND STATE PROPERTIES OF A=20 ISOBARS
Authors: BHAGWAT A. , GAMBHIR Y. K.
Published: November 2003

The ground state nucleon (neutron and proton) distributions for A=20 isobars (Z=6–12) are investigated. For this purpose, the relativistic mean field equations are solved in the coordinate space and also by using the conventional basis expansion method. The pairing is treated in the simple constant gap approximation and also self consistently through the Bogoliubov transformation employing the realistic Gogny D1S interaction as well as the zero range density dependent effective interaction. The comparative study of the results thus obtained indicates the level and the extent of differences in the physical observables like binding energies, sizes, densities, etc. of these nuclei, arising due to the use of these different variants of solving the RMF/RHB equations. Though the results are qualitatively similar, the deviations do appear at a finer level, especially for large Tz (20 O and 20 N ). The calculations also reveal mirror symmetry about Tz=0 for all physical observables, which is in accordance with the experiment. The calculated nucleon densities are compared with those obtained by using a semi-phenomenological model that incorporates correctly the asymptotic behavior. The reaction cross-sections with these A=20 isobars as projectiles incident on a 12 C target at 950 A MeV incident energy, calculated within the Glauber model using the RMF/RHB and model densities agree well with the experiment.
ANGULAR DISTRIBUTIONS OF TARGET BLACK FRAGMENTS IN NUCLEUS–NUCLEUS COLLISIONS AT HIGH ENERGY
Authors: LIU FU-HU , ABD ALLAH NABIL N. , ZHANG DONG-HAI , DUAN MAI-YING
Published: November 2003

The experimental results of space, azimuthal, and projected angular distributions of target black fragments produced in silicon-emulsion collisions at 4.5A GeV/c (the Dubna energy) are reported. A multi-source ideal gas model is suggested to describe the experimental angular distributions. The Monte Carlo calculated results are in agreement with the experimental data.
ABOUT EXCITED STATES OF DEFORMABLE NON-AXIAL ODD NUCLEI
Authors: SHARIPOV SH. , ERMAMATOV M. J.
Published: November 2003

Rotationally single-particle and vibrational excitations of deformable odd non-axial odd nuclei are investigated with allowance for the interaction of collective and single-particle states. The ratios of excitation energies, of reduced probabilities of E2 transitions, and of quadrupole moments for deformable non-axial odd nuclei are calculated up to high-spin states.
The RTDEVS/CORBA Environment for Simulation-Based Design of Distributed Real-Time Systems
Authors: Cho Young Kwan , Hu Xiaolin , Zeigler Bernard P.
Published: November 2003

The increasing complexity of large-scale distributed real-time systems demands powerful real-time object computing technologies. Furthermore, systematic design approaches are needed to support analysis, design, test, and implementation of these systems. The authors discuss RTDEVS/CORBA, an implementation of discrete event system specification (DEVS) modeling and simulation theory based on real-time CORBA communication middleware. With RTDEVS/CORBA, the software model of a complex distributed real-time system can be designed and then tested in a virtual testing environment and finally executed in a real distributed environment. This model continuity and simulation-based design approach effectively manages software complexity and consistency problems for complex systems, increases the flexibility for test configurations, and reduces the time and cost for testing. The layered architecture and different implementation issues of RTDEVS/CORBA are studied and discussed. An example application is then given to show how RTDEVS/CORBA supports a framework for model continuity in distributed real-time modeling and simulation.
Enhanced Decision Modeling Using Multiagent System Simulation
Authors: Sokolowski John A.
Published: November 2003

Modeling and simulation is being used more and more to capture our physical world in a computational form. However, simulating the mental processes that go on within the mind is a complex task that has met with far less success. To improve on this situation, the author developed a computational model of the decision process used by experienced decision makers. This model has, as its basis, the cognitive decision theory entitled naturalistic decision making and its specific implementation, called recognition primed decision (RPD) making. Specifically, this research developed a model that mimicked the decision process of a senior military commander at the operational level of warfare. The model, called RPDAgent, was validated against decisions made by actual military officers. RPDAgent produced decisions that were equivalent to its human counterparts—they were not optimum decisions, but they reflected the variability inherent in those made by humans in an operational military environment.
Distributed Supply Chain Simulation as a Decision Support Tool for the Semiconductor Industry
Authors: Lendermann Peter , Julka Nirupam , Gan Boon Ping , Chen Dan , McGinnis Leon F. , McGinnis Joel P.
Published: November 2003

The need for better understanding, control, and optimization of supply chains is being recognized more than ever in the new economy. Simulation holds a great potential in portraying the dynamic evolution of supply chains and providing appropriate decision support to address challenges arising from high variability and stochastic uncertainty. Realizing high-fidelity supply chain simulation will require integration of individual supply chain component simulation models and planning systems, shielding to prevent sensitive data from being shared indiscriminately, and even the geographical distribution of the supply chain component models. The authors discuss various conceptual and technical issues that have been successfully addressed to realize a prototype of distributed semiconductor supply chain simulation as well as implementation approaches that can be pursued. The prototype emulates a semiconductor supply chain consisting of two wafer fabs, an assembly and test facility, a distribution center, a warehouse, a supply chain planning module, a logistics provider, and customers.
Traffic Analysis and Simulation of a Prioritized Shared Medium
Authors: Evans Jeffrey J. , Hood Cynthia S. , Dickens Phillip M.
Published: November 2003

This work studies the delay effects resulting from heterogeneous traffic types competing for communications resources on a prioritized shared medium using a fixed access and admission control scheme. This research focuses on a specific class of hybrid fiber coaxial residential Internet access system. Such systems have three separate traffic classes: voice, modem, and high-speed data. The authors use analysis, modeling, and simulation to understand how the combination of these three traffic classes, all competing for finite and prioritized bandwidth resources, affects the “perceived” quality of service by the end user. The authors develop analytic models for the various traffic types being considered and validate the individual models using simulation. They show that traditional modeling techniques are not able to effectively capture the behavior of such real-world systems, and they demonstrate that their techniques are quite useful for gaining insight into the behavior and performance of these systems.
Uncontested Seats and the Evolution of Party Competition
Authors: Sharman Campbell
Published: November 2003

Representative democracy presumes competitive elections at which voters have a choice of candidates. This is consistent with the current nature of electoral campaigning, which is system-wide and embraces every opportunity for partisan competition. From this perspective, uncontested seats in parliamentary systems are associated with earlier stages of representative government before modern parties emerged. Yet a survey of Australian state and federal general elections since 1890 shows that uncontested seats persisted in most systems well after the establishment of the current party system and, in two states, until the 1980s. In examining various explanations for the existence of uncontested seats in parliamentary systems, the article finds that the nature of the electoral system, the characteristics of the party system and party organization are key factors. Given a single-member district electoral system, the pattern of uncontested seats can be used as an indicator of the evolution of the party system and the structure of partisan competition.
Centre Politics in Russia and Ukraine
Authors: Protsyk Oleh , Wilson Andrew
Published: November 2003

In this article we examine the manner in which clientelistic and programmatic types of party competition structure centre politics in Russia and Ukraine. The main research focus is on variations in the size of parliamentary factions that claim to be centrist in their ideological orientation. Changes in the composition of centre factions, their voting behaviour and changes in membership size are compared with each other and with a similar analysis for left and right parties. Data from the 1994–8 and 1998–2002 parliamentary terms in Ukraine and the 1993–5 and 1995–9 parliamentary terms in Russia are utilized in the research. Our findings indicate that patterns of rising and falling faction size are closely related to variations in the access of factions to state resources and the extent of voting conformity with executive initiatives, rather than electoral incentives and/or rules of parliamentary procedure.
Performance, Live Culture and Things of the Heart
Authors: Phelan Peggy
Published: November 2003

Having worked in the Department of Performance Studies, Tisch School of the Arts, New York University, from 1985 to 2002, Peggy Phelan is now the Ann O’Day Maples Chair in the Arts at Stanford University. She is the author of Unmarked: The Politics of Performance (1993), Mourning Sex: Performing Public Memories (1997) and the forthcoming Death Rehearsals: The Performances of Andy Warhol and Ronald Reagan, as well as survey essays for the art catalogues Art and Feminism (2001) and Pipilotti Rist (2001). She is co- editor with the late Lynda Hart of Acting Out: Feminist Performances (1993) and with Jill Lane of The Ends of Performance (1998). Professor Phelan has also written plays and performances and has exhibited her visual art. She has made significant contributions across the Arts and Humanities, particularly at the points where live culture, feminism, psychoanalysis, deconstruction, and critical theory meet. In this interview Professor Phelan speaks about some of the awkward grey areas between Performance Studies and Visual Cultural Studies, as well as the themes and topics at the heart of her writing and her practice. These include feminism, performance, psychoanalysis and aesthetics; for Phelan, most of these themes touch on mourning, death and love.
New simple model of dynamic hysteresis
Authors: Gurfil Pini , Friedland Bernard
Published: November 2003

Although the most commonly used hysteresis models are static, in some applications these models constitute an unacceptable simplification of physical behaviour. This includes ferro-magnetic hysteresis, plasticity and friction, which are dynamic phenomena. Consequently, this paper is aimed at presenting a new simple model of dynamic hysteresis, which is more appropriate for modelling of real-life hysteresis effects. The suggested model might be used as a building block for the development of various dynamic hysteresis models. It is proved that at low input rates, this model is closely related to static hysteresis, and it therefore constitutes a generic framework for modelling of hysteresis. Finally, it is shown that stability analysis of a closed-loop system containing simple dynamic hysteresis in feedback can be analysed in a straightforward manner using absolute stability theory.
Performance assessment and benchmarking LQG predictive optimal controllers for discrete-time state-space systems
Authors: Grimble M. J.
Published: November 2003

The performance assessment and benchmarking of discrete-time multivariable LQG predictive optimal control problems is considered for systems represented in state equation form. The class of predictive controllers represents the most popular multivariable design methods for the process industries. It is claimed that these methods provide improved performance but the question addressed is how this performance should be judged. A multistep LQGPC optimal control cost-function is minimized where future set-point or reference knowledge is assumed. The predictive control cost-function includes the future tracking error and control signal components. The state-equation system description can be written in terms of these future inputs, so that the model includes the outputs for time t and a vector of future outputs. The benchmark cost values are obtained from the solution of appropriate Riccati and Lyapunov equations. The results throw new light on the relationship between predictive, LQ and LQG control laws and more importantly into the way the performance of predictive controls should be assessed.
Myoelectric control and assessment of teleoperated robot devices
Authors: Robinson Paul , Radix Cathy A. , Knight Matthew J.
Published: November 2003

Recent advances in the detection and identification of below-elbow myoelectric signals have resulted in a possible alternative to traditional teleoperation control methods such as joysticks, exoskeletons and slave manipulators. This paper describes a myoelectric control system based upon a single electrode positioned on the upper forearm. A potentially powerful method of objectively assessing the performance of teleoperated systems is also examined. The implications of this work for teleoperation system design and implementation are reviewed, and possible future research directions indicated.
Micromechatronics in surgery
Authors: Carrozza Maria Chiara , Dario Paolo , Jay Louis Phee Soo
Published: November 2003

There is a fast growing acceptance of minimally invasive surgery (MIS), in which surgical procedures are performed with the least possible damage to healthy organs and tissues. The reduction of recovery time, postoperative pain, infection risks and costs are some of the many advantages of MIS. Micromechatronic technologies involve the miniaturization of mechatronics devices like precision mechanisms, sensors, actuators and embedded electronics. They have played and will play a very important role in the advancement of MIS. They allow the possibilities of enhancing the surgeon’s abilities where current MIS techniques do not permit the full range of human dexterity and perception. This paper discusses the objectives, roles, and some present and future applications of micromechatronics in surgery.
A Stewart platform for precision surgery
Authors: Wapler Matthias , Urban Volker , Weisener Thomas , Stallkamp Jan , Dürr Mark , Hiller Andrea
Published: November 2003

New therapies, such as cell implants, will in future require teleoperators capable of repeatable positioning accuracy of 10 mm and better. This paper describes the design of a Stewart platform (hexapod robot system) which can be used for precision microsurgery in a number of different medical disciplines. The system design is discussed in detail and an overview of potential applications is given. Also, results are reported on the application in neuroendoscopy.
The thermal performance of a prototype dynamically insulated wall
Authors: Baker P H
Published: November 2003

The concept of dynamic insulation is to draw air from the outside into a building through air permeable insulation, thereby collecting heat usually lost to the outside by conduction. The performance of the dynamic insulation can be characterized by a dynamic U-value, which is a function of the air velocity. As part of a wider study of dynamic insulation, an outdoor PASSYS test cell was used to determine the thermal performance of a prototype dynamically insulated wall for a range of air velocities. The thermal transmission losses, solar gains and ventilation heat recovery have been determined over a range of ventilation rates through the wall. The in‘ uence of the air‘ ow rate on the air supply and internal wall surface temperatures was also investigated.
Fuzzy control strategies to provide cost and energy efficient high quality indoor environments in buildings with high occupant densities
Authors: Shepherd A B , Batty W J
Published: November 2003

Since the oil crises of the 1970s building professionals have become increasingly aware of the effects of their design decisions on the energy consumption rates in buildings. Often this has led to strategies that have compromised aspects of human requirements such as thermal comfort or air quality. When this has been combined with an architectural approach that often takes little heed of local climate or custom the result has been uncomfortable buildings that are disliked by and have often affected the health of their occupants.

The comfort of building occupants is dependant on many environmental parameters including those provided by the building envelope, building environmental services and control systems. Inadequate design and control can lead to reductions of occupant comfort, energy efficiency and cost efficiency. To achieve a high quality internal environment with good energy and cost efficiencies, the interactions between the contributory factors must be taken into consideration. An examination of the notion of indoor environmental quality and the potential for control strategies and methodologies for this multivariate problem are considered within the contexts of energy efficiency and running costs. The use of fuzzy logic control is examined as a technical response to this dilemma. A high level fuzzy supervisor was used to make control decisions on the best course of action to achieve high levels of indoor environmental quality while taking into account effects on energy and cost efficiency. Simulation results indicated the potential for improvements in system operation.
Domestic ventilation rates, indoor humidity and dust mite allergens: are our homes causing the asthma pandemic?
Authors: Howieson S G , Lawson A , McSharry C , Morris G , McKenzie E , Jackson J
Published: November 2003

This paper is concerned with historical changes in domestic ventilation rates, relative humidity and the associated risk of house dust mite colonization. A controlled trial evaluated allergen and water vapour control measures on the level of house dust mite (HDM) Der p1 allergen and indoor humidity, concurrently with changes in lung function in 54 subjects who completed the protocol. Mechanical heat recovery ventilation units significantly reduced moisture content in the active group, while HDM allergen reservoirs in carpets and beds were reduced by circa 96%. Self reported health status confirmed a significant clinical improvement in the active group. The study can form the basis for assessing minimum winter ventilation rates that can suppress RH below the critical ambient equilibrium humidity of 60% and thus inhibit dust mite colonization and activity in temperate and maritime in‘ uenced climatic regions.
Towards the efficient use of simulation in building performance analysis: a user survey
Authors: Pilgrim M , Bouchlaghem N , Loveday D , Holmes M
Published: November 2003

Inadequate presentation of analytical results has been identified as a barrier to the use of simulation tools in the construction industry. The objective of this paper is to substantiate the existence of this barrier and to provide data to support research into its effective removal. The approach taken is to survey users by means of an online questionnaire and semi-structured interviews. Survey data is presented for each step of the analytical process alongside details of the respondents' levels of experience with various software applications. The majority of respondents were either building services or structural engineers and an intergroup comparison is made. Building services engineers of various levels of experience participated in follow-up interviews and the results are presented. The survey results indicate that whilst difficulties of working with analytical results are recognized as a barrier to using simulation other barriers are perceived to be a greater hindrance. Users were also generally happy with the presentation of their results. However the interviewees all described the lengthy process required to validate their analytical models and stated that their tools require improvement to aid this process. The paper argues that whilst not recognized as the greatest barrier to the use of simulation tools there is justification for improving the manipulation and presentation of analytical results.
Experimental energy performance of open cooling towers used under low and variable approach conditions for indirect evaporative cooling in buildings
Authors: Costelloe B , Finn D
Published: November 2003

The success of chilled ceilings and displacement ventilation systems as a means of sensible cooling in buildings has prompted a review of evaporative cooling technology as an effective means of generating the required cooling water. When such cooling water is generated at low approach conditions (2–5 K), at the higher temperatures required in these systems (14–18°C), very high levels of availability result. In many north western European locations the levels of availability are such that the prospect of supplanting rather than simply supplementing the refrigeration system, for sensible cooling purposes, arises. The viability of the technique, however, largely depends on achieving low approach conditions, at acceptable levels of energy performance. Hence the need to investigate the energy performance of the process. This paper presents the results of recent experimental research into: i) the achievement of low approach conditions in an evaporative cooling test rig; and ii) the energy performance of this test rig when generating cooling water, indirectly, at the temperatures required for chilled ceilings. Energy performance is presented for a range of specifi c conditions and typical annual effi ciencies of cooling water generation are determined. Results are compared with typical energy effi ciencies of conventional, vapour compression based, refrigeration systems. A signifi cant potential for improved annual energy performance, is shown.
Commissioning of AHU sensors using principal component analysis method
Authors: Xiao Fu , Wang Shengwei
Published: November 2003

Principal component analysis (PCA) models are implemented for monitoring and fault detection and diagnosis (FDD) of air-handling units (AHUs), which is modified to solve the problems caused by the nonlinearity and variations in the environment. Independent heat balance and pressure-‘ ow balance models are developed to reduce the effects of the system nonlinearity and to make the PCA method valid in different control modes. Sensor faults are detected and partly isolated using Q-statistic (square prediction error) and Q-contribution plot. Simulation tests are conducted to demonstrate the use of the PCA method for automatic commissioning of AHU monitoring instrumentations and to validate the PCA method in detecting and diagnosing the AHU sensor faults under various typical operating conditions.
A new design guideline for the heating and cooling curve in AHU units of HVAC systems
Authors: Elkhuizen P A , Peitsman H C , Wienk W J
Published: November 2003

New Dutch office buildings are built under strict energy efficient legislation and are well equipped with insulation, condensing boilers, heat recovery systems, and so on. Despite this, many buildings do not have good energy efficiency and also do not meet comfort requirements. This has led to a large number of complaints. The problem seems to be that ‘common’ energy control strategies (heating/ cooling curves) are often used, most of the curves were based on buildings with low levels of building shell heating resistance, no additional insulation and single glazing. When these control strategies are used in modern office buildings, too much energy is used due to a mismatch between heating and cooling demands. Energy savings of up to 35% can be realized without significant financial investments by devoting extra attention to the settings of the heating/ cooling curve in the central air handling units (AHUs) of HVAC systems without loss of comfort. In most cases the number of complaints will also be reduced. The design method can be used in both new and existing buildings. The first part of this paper presents a brief description of the method used to realize this energy saving. The brief description is followed with a practical example of this method. The intention is that the approach will generate a building-specific heating/cooling curve based on an energetic optimum between the demand for heating and cooling in the zones. The input data used to generate the function cover the characteristics of the building, the organization, and the HVAC equipment.
Parameter estimation based model of water-to-water heat pumps with scroll compressors and water/glycol solutions
Authors: Jin Hui , Spitler J
Published: November 2003

A recently developed parameter estimation-based steady state simulation model of water-to-water reciprocating vapor compression heat pumps (Jin H, Spitler JD, ASHRAE Trans. 2002; 108(1)) is built up from models of individual components. Various unspecified parameters for individual components are estimated from catalogue data for the overall unit performance. This approach has been shown to give better accuracy and extrapolation capability than polynomial fit models. It has also been shown to give accuracy similar to more detailed deterministic models that require additional information not typically available to an engineer performing energy analysis. This paper covers two important extensions to the model — scroll compressors and glycol/water mixtures. A five-parameter (including intake volumetric flow rate, built-in compression ratio, leakage coefficient and two efficiency-related parameters) scroll compressor model replaces the reciprocating compressor model previously used. While necessary in some applications for providing protection from freezing, water/glycol solutions adversely impact heat transfer performance. A procedure for adjusting the model parameters to account for the change in working fluids is presented. In addition, a preliminary field validation of the modified water-to-water heat pump model is presented. The heat pump utilized both a scroll compressor and a propylene glycol/water mixture as the working fluid.
Three heresies of language testing research
Authors: Davies Alan
Published: November 2003

This article gives a personal view of the history of Anglo-American language testing over the last half-century. It argues that major developments in the field have tended to be embraced too enthusiastically, so that they have led to unbalanced views (or ‘heresies’) concerning the construct definition of language, the scope of test impact and the value of new methods of test delivery and analysis. The article considers in turn the move to integrative and then communicative testing in the 1970s and 1980s; the recent concerns about washback, impact, ethics and politics in language testing; and the effects of innovations such as item response theory and computer-based testing. Despite their unsettling in‘ uence, heresies should be welcomed for the challenge they pose to established theory and practice.
Second language interaction: current perspectives and future trends
Authors: Chalhoub-Deville Micheline
Published: November 2003

This article considers how the nature of interaction may best be represented in the second language (L2) construct. The starting point is Bachman’s model of communicative language ability which, it is argued, incorporates interaction from an individual-focused cognitive perspective. The alternative view advocated here is that individual ability and contextual facets interact in ways that change them both. Thus, ‘an ability - in language user - in context’ view is to be preferred over Bachman’s ‘ability - in language user’ representation. Acceptance of this new approach entails a local, context-bound view of language ability, which is difficult to reconcile with the tester’s need for score generalizability. The way forward is to recognize that, while some contexts activate stable ability features, others produce more variable performance from learners. Thus, the focus of both theory formulation and empirical research should be on how to account for inconsistent performance in particular contexts from a social interactional perspective.
Creating a self-rating instrument for second language writing: from idea to implementation
Authors: Luoma Sari , Tarnanen Mirja
Published: November 2003

This article reports on the development of a self-rating instrument for writing. The instrument engages learners in responding to a writing task and assessing their own proficiency against a set of benchmarks. The technical and conceptual framework for the instrument is the DIALANG project, a diagnostic language assessment system for 14 languages on the internet. The report comprises a description of the self-rating procedure, an account of instrument development, a report on a usability study with six learners of Finnish as a second language, and our test-developer analysis of the process and products of the self-rating instrument. The data consists of records of task and benchmark development, participant background data, the texts that the learners wrote, video recordings of their screen actions during the self-rating process, immediate retrospective interviews with the learners, and teacher ratings of the learner texts. The discussion concentrates on the concepts that underlie the self-rating process and the potential offered by this approach for the learning, teaching, and assessment of second language writing.
Acquisition of literacy skills by children with severe disability
Authors: Basil C , Reyes S
Published: November 2003

Many students with autism, intellectual impairment, and multiple impairments experience difficulties in acquiring literacy skills. An intervention programme based on the multimedia software Delta Messages and a scaffolding approach was used with severely disabled children. They showed significant gains in sentence production through a whole-word selection strategy, which was targeted in the programme, and in the ability to synthesise and spell words, tasks that were not targeted in the reading instruction. This suggests that massed practice of self-initiated and meaningful literacy activities can promote the acquisition of literacy by students with severe disabilities and limited written language skills.
A pilot study of paraprofessional screening of child language in community settings
Authors: Pickstone Caroline
Published: November 2003

A pilot study is reported presenting reliability and validity data for screening for delayed language in an area of urban disadvantage. Paraprofessional staff screened children between 19 and 21 months (n 50) during routine home visits. Results show that the workers were reliable (0.78–1.0, Kappa) using a standardized test (First Words Test) and the screening achieved sensitivity of 1.0 and specificity of 0.7. The prevalence of language delays was high; 18–31% of those screened would have been referred for specialist assessment. The identification of false positives on screening may identify children who give cause for concern and allow targeting of early educational interventions.
Following directions: Rehearsal and visualization strategies for children with specific language impairment
Authors: Gill Cynthia B. , Klecan-Aker Joan , Roberts Tim , Fredenburg Karen A.
Published: November 2003

Children with specific language impairment (SLI) may have inefficient memory or memory management for auditory and visual representation systems. This study sought to determine if strategy training would create any residual enhancement of these memory management systems. Data revealed that immediately following intervention, elementary students taught to use a rehearsal strategy and those taught to use a rehearsal/visualization strategy made significant gains over a traditional language therapy group on a standardized test of following directions. However, only the rehearsal/visualization group retained its gains over the traditional group eight months after the intervention. These findings support the long-term efficacy of systematic training via rehearsal/visualization to increase the ability of children with SLI to follow verbal directions.
Developing an expressive language assessment for children in Rochdale with a Pakistani heritage background
Authors: Pert Sean , Letts Carolyn
Published: November 2003

This paper reports work in progress to develop an assessment procedure for expressive language, to be used with children living in the Rochdale area of the UK and speaking Mirpuri, Punjabi and/or Urdu. The assessment materials and procedure are described, together with the principles for scoring. Normative data is currently being collected. Children tested so far have demonstrated the need to allow for code-switching and lexical borrowing and that attention to ‘literal’ translation of the target language is required. Discrepancies between reported and actual languages used are also noted. Expressive language appears unexpectedly sparse in some cases. Possible reasons for this are discussed. This research has highlighted many difficulties in attempting to construct an assessment of this kind.
Phonological processing: a platform for assisting second-language learners with English spelling
Authors: Seeff-Gabriel Belinda
Published: November 2003

The English spelling abilities of 22 adolescent English second language learners were related to their input processing skills. Strong correlations were found between their spelling of words containing first language (L1) and second language (L2) vowels and their auditory discrimination and phonological representation of these words. An increased length of exposure to English first language models was found to have a positive effect on their spelling and processing skills. Semantics was found to play a key role in the processing of words containing L1 and L2 vowels. Practical implications for educators and speech and language therapists working within multilingual classrooms are discussed.
Syntactic development in ‘ uent children, children who stutter, and children who have English as an additional language
Authors: Howell Peter , Davis Stephen , Au-Yeung James
Published: November 2003

Children aged between two and 10 years were assessed on a new reception of syntax test (ROST). Validations of the test are reported for monolingual ‘ uent control children under five (by examining the relationship with mean length of utterance and the Oxford Communication Development Inventory) and for over fives (relationship with a new judgement of grammaticality test using syntactic categories common to the two tests). Performance of these children was compared with performance of children who stutter and children with English as an additional language. In this study, the test was divided into under-five and over-five forms. Any young child progressing to the over-five syntactic categories, or any older child doing the under-five syntactic categories was dropped from the analysis. ROST scores prepared according to this scheme led to no differences between the control and either of the subject groups tested. However, compared to controls, the children with English as an additional language (but not children who stutter) had a significantly higher proportion of children above five who did the under-five categories (and were, therefore, excluded from the analyses). The higher proportion of children who did the under-five syntactic categories in the English as an additional language group indicates that group scores would have been lower if their syntax results had been included in the analysis. Further analyses provided some evidence that two groups with English as an additional language (Turkish and Cantonese speakers) did not perform any better on selected syntactic categories in their native language compared with their performance in English.
Assessing phonologies in bilingual Swedish-Arabic children with and without language impairment
Authors: Salameh Eva-Kristina , Nettelbladt Ulrika , Norlin Kjell
Published: November 2003

Ten Swedish-Arabic children with severe language impairment (LI) and 10 matched controls were tested with Swedish and Arabic phonology tests. The children with severe LI displayed significantly more of both syntagmatic and paradigmatic processes in both languages. The results are also discussed in relation to monolingual children in Swedish and Arabic, both children with a normal language development as well as with a language impairment. Both groups of Swedish-Arabic children tended to develop their two languages in the same way as monolingual children in each language, with some exceptions. Both groups had substantial lexical problems, especially in Arabic. Exposure to Swedish was an important variable relative to number of syntagmatic processes. The importance of assessing both languages is emphasized.
Lexical and discourse factors in the second language acquisition of Spanish word order
Authors: Hertel Tammy Jandrey
Published: November 2003

This study investigates the acquisition of Spanish word order by native speakers of English. Specifically, it considers the development of sensitivity to the distinct interpretations of subject-verb (SV) vs. verb-subject (VS) order, as determined by lexical verb class (unaccusative and unergative verbs) and discourse structure.Participants included a native speaker control group and learners at four proficiency levels. Results from a contextualized production task indicate that beginning learners transferred the SV order of English for all structures. Intermediate learners showed a gradual increase in the production of lexically and discourse-determined inversion, although their data was also characterized by indeterminacy and variability. The advanced learners demonstrated a sensitivity to the word order effects of unaccusativity and discourse factors, but also tended to overgeneralize inversion to unergative verbs in a neutral discourse context.
English idioms in the first language and second language lexicon: a dual representation approach
Authors: Abel Beate
Published: November 2003

In two empirical studies, judgements that native speakers of German make about the decomposability of English idioms were investigated. A decomposable idiom is an idiom whose individual components contribute to its figurative meaning, whereas the constituents of a nondecomposable idiom do not make such a contribution. The findings were analysed and compared to native judgements. The Model of Dual Idiom Representation is introduced in order to explain the differences between the two groups. At the lexical level, the model postulates the parallel existence of idiom entries and constituent entries. The degree of decomposability and the frequency with which the idiom is encountered determine its lexical representation. If there is no idiom entry for a particular idiom, conceptual representations are accessed during comprehension. Because nonnative speakers encounter idioms less often than native speakers, the first language (L1) and second language (L2) lexicon vary with regard to the number of idiom entries.
Two textbook representations of second language acquisition and Universal Grammar: ‘access’ and ‘constraint’
Authors: Thomas Margaret
Published: November 2003

Two textbooks written by Lydia White, one published in 1989 and the other in 2003, introduce generative research on second language acquisition and evaluate existing proposals about the role of Universal Grammar. Comparison of the two texts provides an opportunity to examine some of the conventions the field uses in representing itself to a novice readership. It also brings to light certain aspects of the field’s development during a 14- year interval. A point of particular interest is that this interval spans a shift in the language commonly used to pose questions about the relationship of Universal Grammar to second language acquisition, from the metaphor of ‘access’ to the metaphor of ‘constraint’.
Antegrade cerebral perfusion with hypothermic circulatory arrest: a case report
Authors: Fitzgerald David , Resley Justin , Speir Alan , Munoz Ruben , Hill Aaron
Published: November 2003

Techniques for the surgical correction of aortic aneurysms have steadily improved since the first described successful repair in 1955 by DeBakey et al.1 Despite these improvements, postoperative neurological complications remain a major factor in determining an adverse outcome. By using Deep Hypothermic Circulatory Arrest (DHCA), Retrograde Cerebral Perfusion (RCP) and now Selective Antegrade Cerebral Perfusion (SACP), the surgeon may provide better cerebral protection during extensive arch reconstruction.

A 73-year-old female presented with an abnormal chest X-ray. Computerized tomography scan revealed a 4.5 cm mid aortic saccular arch aneurysm. Surgical intervention using cardiopulmonary bypass (CPB) with systemic cooling to 24°C was employed. SACP was administered via cannulation of the innominate artery and the left common carotid artery using pediatric cannulae. Flow rates of 10 mL/kg/min and perfusion pressures of 60-90 mmHg were employed. Transcranial oximetry was used to monitor cerebral oxygen consumption. Circulatory arrest with SACP lasted for 36 min. Total bypass time was 178 min and myocardial ischemic time was 63 min. The patient was discharged on postoperative day five with no evident sequelae. While RCP has many benefits, SACP as used in this procedure may further improve patient outcome.