bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advantages of and developments in dual bluff-body vortex flowmeters
Authors: Bentley J.P. , Nichols A.R. 
Published: November 2007

The paper begins by reviewing the main performance characteristics of vortex flowmeters - eg, signal stength, signal-to-noise ratio, frequency, repeatability, meter factor and blockage ratio. It then develops a performance equation which calculates the total time required to capture sufficient cycles to achieve a given overall repeatability. From this equation we see that for a typical single bluff-body vortex meter the time required to achieve an overall repeatability of 0.02% is 387min. This underlines the point that single bluff-body meters are in general not very useful for fiscal metering or custody-transfer applications. The paper then reviews the general principles of vortex shedding from two bluff bodies in tandem, explaining that there are two distinct flow regimes, depending on whether the bluff-body separation is less than, or greater than, a critical value. A summary of results is presented for initial tests on 15 combinations of two rectangular bluff bodies in tandem, together with three single bluff bodies for comparison. These initial tests were carried out in a 300 mm diameter wind tunnel at a free-stream velocity of 6.5 mls and a turbulence intensity of 0.5%. Seven combinations with optimum separations were then tested over a free-stream velocity range between 0.6 and 13.0 mls and at three turbulence levels. Detailed results showing the variation in RMS vortex velocity, signal-to-noise ratio, meter factor and percentage frequency standard deviation with free-stream velocity are presented. Certain of these combinations give a far more regular and repeatable vortex signal than single bluff bodies; the time required to achieve an overall repeatability of 0.02% is as low as 33 min. All of the above dual combinations have a small separation, so that vortex shedding takes place behind the downstream bluff body only. Detailed maps of the vortex field around certain dual combinations are presented which show that, in certain cases, the oscillations of boundary layers in the gap are strongly correlated with the oscillations of boundary layers moving around the bluff bodies. Thus the vortex shedding from the downstream bluff body is reinforced by oscillating boundary layers moving through the gap.
Improved transient fault simulation on a laboratory model of a turbine-generator
Authors: Nouri H. , Colfer G.W. 
Published: November 2007

In order to enable a simulated fault current in the region of 4000 A to produce a pulsating magnetisation in the stator coil, an arrangement of a parallel tuned-circuit was constructed. The performance characteristics of the tuned-circuit were assessed from an analytical solution (Transient response method) and modelling on an Apollo computer using the transient response package. The inrush current which is associated with the starting of the tuned-circuit was controlled with a soft-start, which increased the input voltage across the coil from zero to full preset value in 50 cycles. The soft-start circuit consisted of two anti-parallel thyristors, current-limiting resistor, phase-angle trigger unit and its control circuitry. Spurious triggering of the thyristor was greatly reduced by placing the current-limiting resistor in between the supply and the thyristor. The possible causes are discussed. A detailed comparison of the measured flux for the fault current of 4000A at an air-gap of 75 mm, for conditions with and without the endbell, at the end of the rotor suggests that the conduction current is dependent on the contact resistance at the endbell and rotor interface.
Adaptive control of industrial processes
Authors: Smith L.S.P.S. 
Published: November 2007

The paper reviews adaptive tuning techniques which have been implemented in commercial controllers, and successfully applied to a variety of industrial processes. Some characteristics of industrial processes which cause problems for adaptive tuners are discussed, together with solutions to these prablems. Gain-scheduling is shown to be a useful alternative to continuously adaptive techniques where robustness is required with changing plant conditions. The closed-loop cycling method is discussed both as an independent auto-tuning technique, and as a pre-tune for parameterising continuously adaptive tuners. The strengths and weaknesses of waveform analysis techniques and model-based predictive controllers are highlighted. A novel self-tuning output algorithm for driving motorised valves is proposed as a solution to problems encountered in controlling processes using these actuators.
A practical optical force-feedback microphone
Authors: Karatzas L.S. , Keating D.A. , Usher M.J. 
Published: November 2007

A novel technique of measuring diaphragm displacement in microphones using a laser-diode Fabry-Perot system is presented. The microphone diaphragm is held within an electrostatic force-feedback loop so as to improve the performance. A second loop operates around the laser, for noise minimisation purposes. Following a brief introduction to the subject of optical detection in microphones, the modified Fabry-Perot interferometer is described, and the complete system with the two feedback loops presented. The characteristics of the laser driver and laser diode are examined. Theoretical responses are shown, for different cases, and noise calculations yield the dynamic ranges without feedback. The effect of feedback is then examined, both around the laser (electronic) and around the microphone capsule (electrostatic), and the dynamic ranges are recalculated to show the advantages of feedback. Intended directions for further research are also discussed.
Condition monitoring of automatic control systems using parameter and systems identification: a numerical investigation
Authors: Firoozian R. , Lee C.C. 
Published: November 2007

The intense international competition for reducing manufacturing cost has forced many industrialists to implement total automatic control over a wide range of products and manufacturing processes. This, of course, results in substantial reduction of manpower on the factory floor and the task of condition/performance monitoring must be replaced by appropriate computer based software. Many engineers have employed vibration analysis methods developed in recent years to monitor the condition of critical components such as gearboxes, bearings, belt-drives and rotating elements which are more susceptible to failure than other mechanical parts of machines. However, these methods are suitable for identifying faults that generate substantial increase in vibration level measured at a suitably selected point. The authors argue that the parameter and system identification technique presented in this paper gives far more reliable information about imminent failure than the method mentioned above. The availability of high-quality feedback signals(s) removes the need and difficulty of selecting a suitable transducer. The method is based on the concept that the dynamic behaviour of automatic control systems can be modelled by identifiable linearised/ nonlinear transfer function with constant coefficients. The deviation of each parameter from the norm value indicates the failure/wear of respective elements in the system. The paper demonstrates that these parameters can be estimated relatively simply with efficient use of computer time and memory. The method uses state variable filter (SVF) and recursive least square optimisation algorithm so that it may be implemented as an ON/OFF-line condition monitoring package. The numerical investigation from simulated data shows that the identified coefficients may be used to predict components failure. In addition, the algorithm is capable of identifying the relevant coefficients accurately if the noise level on the measured signal is less than 10% which is usually the case for most automatic control systems with high-performance feedback transducers. The procedure of designing a suitable filter capable of converging rapidly is discussed and the results show that a compromise has to be made between speed of conver-gence and the magnitude of noise in the feedback signal.
Image guided orthopaedic surgery design and analysis
Authors: Phillips R. , Viant W.J. , Mohsen A.M.M.A. , Griffiths J.G. , Bell M.A. , Cain T.J. , Sherman K.P. , Karpinski M.R.K. 
Published: November 2007

Within the next few years it is envisaged that a number of computer assisted surgery products will become available. For many surgical procedures, outcome of surgery,, will rely on the accuracy and repeatability with which a computer assisted surgical toolperforms its task. This paper presents a Computer Assisted Orthopaedic System (CAOS) which takes an image guided approach to planning and implementing a trajectory, to assist an orthopaedic surgeon. Accurate delivery of this trajectory is achieved via an intelligent guide. This paper details the design issues and identifies the registration and calibration techniques used by the CAOS intelligent guide. The paper also enumerates, and where possible quantifies, thefactors that influence the accuracy performance of the system. Accuracy trees are used to show the root source of inaccuracies and how they propagate and combine in a system.
Achieving benefits using traditional control technologies
Authors: Oglesby M.J. 
Published: November 2007

The basic techniques of cascade and feedforward control are described together with the types of process problem to which they are suited. Their use is illustrated with simple examples. Among these are three-element level control, heat exchanger control and distillation control. The latter example quotes the magnitude of the benefits which can be achieved in practice. Other areas where traditional techniques can be used are given. Amongst these are override controls with an illustration from distillation control, 'valve position control' with an example from a fired heater system and the use of calculated variables demonstrated by heat input control.
Numerical and experimental analysis of laminar flow through square-edged orifice with variable thickness
Authors: Sahin B. , Ceyhan H. 
Published: November 2007

In this work, axisymmetric, viscous, steady, incompressible and laminar flow through square-edged orifices has been studied. A numerical solution of the steady-state vorticity transport equation has been obtained from the two-dimensional Navier-Stokes equations. Finally, streamline patterns, vortex formations and separated flow regions have been predicted. The effects of orifice plate thickness and Reynolds number on the flow characteristics have been investigated numerically and experimentally. The Navier-Stokes equations have also been integrated in order to compute the pressure distributions through the orifice. From these results, the orifice discharge coefficient has been computed and examined as the Reynolds number and the orifice plate thickness were varied. A comparison has been made between the experimental results, the numerical predictions and available experimental results. The predicted flow discharge coefficient values agreed closely with the experimental results.
Stability of nonlinear systems and the effects of time delay control
Authors: Lewis C.P. , Ucar A. , Bishop S.R. 
Published: November 2007

The study of dynamical systems is of significant practical importance. We investigate here the concept of the safe basin and the use of the amplitude/frequency of forcing parameters plane which can be applied to a wide range of dynamical systems including control applications. A computer aided study of the performance of such systems using Matlab/Simulink with a Watcom C/C++ compiler is illustrated. The technique is easy to use and is only limited by the properties of the Matlab/Simulink programme in which the system is simulated. The behaviour of a pressure transducer is used as a simple example; as a further example the stab ility and robustness of a practical control strategy, designed to control chaotic behaviour, has also been investigated.
A functional approach to the attainability of typological targets in L2 acquisition
Authors: Zobl Helmut 
Published: November 2007

This paper proposes a functional, parsing-based approach to the attainability of typological targets in L1 and L2 acquisition. Ideally, there should be a functional synchronization between the order in which principles constituting typological values emerge in learner grammars and the computational demands imposed by the simplest data instantiating a typological value. In L2 acquisition this functional synchronization is jeopardized by the possibility of L1-inspired misparses which may impute more structure to an input string than is consistent with a minimal parse. As a result, the more marked typological setting or the implicans of two grammatical principles in a relationship of logical entailment can appear first in interlanguage grammars. In L1 acquisition, on the other hand, misparses appear to be the result of assuming too little structure. Because of these differences, recovery from an inappropriate value follows different courses in L1 and L2 acquisition. It is proposed that this difference has important implications for the learn-ability of first and second languages.
Evidence for parameter-sensitive acquisition : a contribution to the domain-specific versus central processes debate
Authors: Zobl Helmut 
Published: November 2007

Much current work on L2 acquisition is defined by the hypothesis that adult learners embark on the acquisition task with a language faculty whose structure is significantly less modular that than of the L1 learner. The domain-specific system, which has available to it the principles and conditions of Universal Grammar, has been replaced by content-neutral, central processes and the learner's L1 as the principal means by which an L2 can be internalized. An important corollary of this hypothesis is that acquisition will be piecemeal and will not evidence the effects associated with parameter setting. In this paper we attempt to demonstrate that adult L2 acquisition is module - and parameter-sensitive. The focus of the inquiry falls on the acquisition of the principle of structural government and the English language value of the agreement parameter by Japanese-speaking learners. Although the data supporting the claim come primarily from production, their analyses furnish compelling evidence that central processing, as it is currently understood, cannot account for the way attributes of these parametric choices cohere together.
Learnability and grammar reorganization in L2A: against negative evidence causing the unlearning of verb movement
Authors: Schwartz Bonnie D. , Gubala-Ryzak Magda 
Published: November 2007

This paper reassesses the role of Negative Evidence (NE) in nonnative language acquisition. We argue that the grammar-building process cannot make use of NE to restructure (Interlanguage) grammars - irrespective of logical need. The empirical basis comes from White's (1991a; 1991b) study of French speakers acquiring English, where the 'Verb Movement' parameter and the particular learnability problem of 'unlearning' thematic Verb- movement were the focus. The L2ers start off assuming the L1 value of [+] Verb-movement, thus incorrectly allowing the order S V Adv O in English, and the issue is whether NE can force a switch to the [-] value, whereby S V Adv O should be excluded. While it is indisputable that the L2ers changed their linguistic behaviour as a direct consequence of their exposure to NE, the conclusion we draw is quite distinct from that of White. Based on both the postinstruction data and an argument grounded in formal learnability theory, we show that an inherent contradiction must be imputed to the Interlanguage 'grammar' to account for the results: in addition to no longer permitting S V Adv O, the L2ers also (incorrectly) disallow S V Adv PP; to exclude the latter, the grammar must have 'un learned' base-generating Adverbs to the right of VP but other data dispute this, i.e., S V O/PP Adv is still allowed. Since natural language grammars cannot contain such inherent contradictions, we conclude that a natural language grammar could not be the source of this L2 behaviour. Our explanation is that the L2ers simply extended the *S V Adv O pattern that they were taught. In sum, there is no evidence that NE caused the L2ers to unlearn Verb-movement and hence NE did not restructure the Interlanguage grammar. Implications of this conclusion are discussed in relation to the issues of learnability and 'UG-accessibility' in L2A.
COALA-A computational system for interlanguage analysis
Authors: Pienemann Manfred 
Published: November 2007

This article describes a computational system for the linguistic analysis of language acquisition data (COALA). The system is a combined AI and database tool which allows the user to form highly complex queries about morphosyntactic and semantic structures contained in large sets of data. COALA identifies those sentences that meet the linguistic criteria defined by the user. It allows the user to freely define such linguistic contexts and to step through the sentences identified by the system. COALA then rapidly displays those sentences in their original discourse context. Additionally, COALA can perform statistical analyses in response to structural linguistic queries. This article contains (1) a discussion of the computational approach taken in the design of COALA, (2) a description of the functionality of the system, and (3) a reflection on the validity of the analytical categories contained therein.
Lexical processing in bilinguals
Authors: de Bot Kees , Cox Albert , Ralston Steven , Schaufeli Anneli , Weltens Bert 
Published: November 2007

In this article data from an auditory lexical decision experiment with English-Dutch bilinguals are compared with data from a similar experiment using visual lexical decision. The aim of the experiments was to investigate three factors that may play a role in lexical processing: level of proficiency in the second language, mode of presentation (visual vs. auditory) and cognate- ness of lexical items. The structure of this article is as follows. In the first part a description is given of current theoretical models of the bilingual lexicon. In the second part we present a summary of an experiment on visual lexical decision (Kerkman, 1984; Kerkman and De Bot, 1989), and in the third part we report on the auditory lexical decision experiment. In the last part these two sets of data are discussed in the light of recent theorizing on the bilingual lexicon.
Positive evidence in second language acquisition: some long-term effects
Authors: Trahey Martha 
Published: November 2007

It has been proposed (Krashen, 1981; 1982; 1985; Schwartz and Gubala- Ryzak, 1992; Schwartz, 1986; 1988; 1993) that L2 acquisition proceeds in essentially the same manner as L1 acquisition (the L1 = L2 position). That is, learners acquire underlying unconscious knowledge of a language (called lin guistic competence) simply by being exposed to the linguistic input (called primary linguistic data) in the environment. Instruction and error correction play no role in the development of competence in the L2. This article reports the long-term results of a study investigating the role of primary linguistic data in the acquisition of linguistic competence - in par ticular, the rules of adverb placement in English. This study examines the knowledge of adverb placement of 52 grade-6 francophone students (aver age age: 12 years, 2 months) learning English as a second language (ESL) in Québec schools. A year earlier, these subjects had been exposed over a two- week period to a flood of primary linguistic data on adverb placement in English. Immediately after the input flood, it was found that while the sub jects had learnt which adverb positions were grammatical in English, they still used positions which were ungrammatical in English but grammatical in the L1. The results of the follow-up test reported in this article reveal that one year after the input flood, the subjects' knowledge of adverb placement has not changed. They still use both the grammatical and the ungrammatical adverb positions, indicating that exposure to an abundance of primary lin guistic data on adverb placement did not lead to mastery of this structure. Possible explanations for these results and their implications for the L1 = L2 position are discussed.
Prostacyclin, cardiopulmonary bypass and the alveolar capillary membrane
Authors: Jones DK , Higenbottam TW , Wheeldon D. , Kneeshaw J. , Bethune D. 
Published: November 2007

In a double blind controlled study of 24 patients undergoing coronary artery bypass grafting, 12 received an infusion of prostacyclin at 20 ng/kg/min during cardiopulmonary bypass in an attempt to reduce the previously reported increased alveolar capillary membrane permeability that occurs postoperatively. Prostacyclin significantly reduced platelet activation but had no effect in reducing complement activation or transpulmonary neutrophil sequestration. Alveolar epithelial permeability as assessed by measuring the clearance of inhaled 99mTc-DTPA from lung to blood did not change postoperatively in either group. In order to fully evaluate pulmonary damage following cardiopulmonary bypass a marker for pulmonary endothelial damage may need to be used.
In vitro comparison of cavoatrial (dual stage) cannulae for use during cardiopulmonary bypass
Authors: Riley Jeffrey B , Hardin Scott B , Winn Brad A , Hurdle Michael B 
Published: November 2007

An in vitro normothermic, human blood test circuit was constructed to test four cavoatrial (dual stage) cannulae, their right atrial baskets and IVC tips for venous return flow versus siphon drainage gradient. Simulated patient CVP and ECC oxygenator/venous reservoir inlet resistance were held constant at 10 mmHg and 15 mmHg respectively as siphon gradient was varied from 0 centimetres (cm) to -40 cm of blood. At the same siphon gradients between -10 and -40 cm, the Research Medical, Inc. (RMI) VV 3651 L, its right atrial (RA) basket, and IVC tip yielded significantly greater flows than the Sarns Inc. 12340, CR Bard, Inc. 1969, and the RMI VV 3651 B cannula, except the RMI VV 3651 B RA basket was equivalent to the VV 3651 L basket. The 12340 and 1969 baskets were equivalent. The 1969 IVC tip was superior to the 12340 tip. The mechanism for CPB venous collapse and flutter, its treatment, and the importance of monitoring myocardial temperature, as well as assuring great vein and cardiac decompression during cavoatrial cannulation and aortic cross clamping are outlined.
Platelet damage and haemolysis during bubble oxygenator perfusion with and without arterial line filter, compared to membrane oxygenator perfusion
Authors: Boonstra PW , Vermeulen Fee , Leusink JA , de Nooy EH , van Zalk A. , Soons Jbj , Wildevuur Crh 
Published: November 2007

We determined to what extent a 27 micron depth filter (Bentley Polyfilter bypass blood filter PF427, Bentley Lab., Irvine, California, USA) in the arterial line of a bubble oxygenator (BO) system is responsible for the difference in haemocompatibility between this BO system and a membrane oxygenator (MO) system in which no arterial line filter is used. We studied three groups of patients subjected to long perfusions of approximately three hours: BO perfusion with ( n = 8) and without ( n = 8) the arterial line filter and MO perfusion ( n = 10) without filter. Platelet and erythrocyte damage were evaluated at seven sampling points during perfusion. Also pre- and postoperative bleeding times and postoperative blood loss and blood transfusions up to 18 hours after perfusion were determined. We found that the 27 micron depth filter in the arterial line impairs the haemocompatibility of the BO only to a small extent; the MO remains haematologically superior over the BO even when the arterial line filter is absent from the BO circuit.