bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulating Public Bodies: The Case of Direct Service Organisations in British Local Government
Authors: Ashworth Rachel , Boyne George A , McGarvey Neil , Walker Richard M
Published: August 2002

In recent years regulatory mechanisms and arrangements for public service organisations have become increasingly complex. In this paper we develop a theoretical framework that emphasises the potential importance of the following regulatory problems: regulatee resistance, ritualistic compliance, regulatory capture, performance ambiguity, and absence of performance data. This framework is applied to arrangements for the regulation of direct labour and direct service organisations in Scotland and Wales prior to the ‘Best Value’ regime. The results support the practical relevance of the analytical framework. Furthermore, whereas conventional perspectives suggest that the source of regulatory problems is the behaviour of regulatees, our evidence shows that the behaviour of regulators can also lead to regulatory failure; for example, through ritualistic compliance with procedures. The evidence also reveals a previously unidentified problem concerning a ‘fear of regulation’ on the part of regulators.
Social Participation, Institutional Change, and Land Property in the Building up of Sustainability: A Case Study of Land-Use Conflict in Tenerife (Canary Islands)
Authors: Aguilera-Klink Federico , Sánchez-García Juan
Published: August 2002

This paper is grounded in VALSE (VALuation for Sustainable Environment) methodology, which seeks to understand the ways that concerned people express the ‘values’ of environment. In our research we aim to assess the importance of maintaining these values, and to test the integration of the valuation statements within a real decisionmaking process. The study of the combination of institutional analysis and democratic perspective in land-use conflict in the Canary Islands was used for such assessment and testing. An institutional analysis was carried out in order to account for recent changes in the notion of landownership (through the introduction of environmental and landscape values) and corresponding changes in the institutional framework. A democratic perspective was applied in order to include public expression, debate, and deliberation as valid ways of generating and exchanging knowledge, and as a means of reaching a satisfactory environmental decision. The problem of land use associated with the environmental valuation issue can be adequately understood by studying the social processes responsible for the different land uses. To think in terms of social processes for environmental valuation of the landscape implies concern over a process of collective understanding: the ways values and interests are formed and the way the conflict gives rise to different notions and rules of the game, and to different manners of conceiving and implementing decisionmaking processes and solutions to environmental problems.
Strategic Management of Government-Sponsored R&D Portfolios
Authors: Bozeman Barry , Rogers Juan
Published: August 2002

Although strategic management of R&D portfolios is common practice in private sector R&D, government R&D management tends to be more discrete and ad hoc, focusing on generating maximum output from individual projects. Often, there is no clear notion of the desired public sector output. Whereas private sector R&D evaluation is generally straightforward, with the function of R&D being measured in terms of a company's internal return on investment, the benefits of public-sponsored R&D tend to be more diffuse with respect to both type and impact. Drawing from evidence developed in twenty-four case studies of R&D projects sponsored by the Department of Energy's Office of Basic Energy Sciences, one of the primary sources of funds for basic research in US universities and national laboratories, we examine implications of R&D project impacts for a sort of ‘portfolio management’ of government-sponsored R&D. Although the meaning of ‘portfolio’ is not the same in public sector R&D management, it is nonetheless possible to think strategically about projects and their cumulative impact. Indeed, it is clear that many government R&D managers already do so. In this study, we contrast two types of ‘portfolio’: (1) R&D output portfolios (focusing on one type of scientific output, such as, for example, fundamental knowledge or technology development); and (2) a balanced portfolio that considers both R&D outputs and ‘scientific and technical human capital’, the capacity created by R&D projects. The case-study evidence shows different approaches to achieving each portfolio type. An analysis of the relation of project attributes to output types focuses on aspects of projects potentially under the control of strategic public managers, including magnitude of funding, degree and type of management oversight, and interorganizational and intraorganizational linkages. Each of these variables affects the type of project outputs obtained. From the results, we suggest that a balanced approach to government R&D portfolio management is appropriate for many government agencies. That is, government managers may wish to consider the extent to which their projects both produce traditional outputs such as articles and patents, as well as provide contributions to scientific and technical human capital.
Competitive Bidding in Urban Regeneration: Stimulus or Disillusionment for the Losers?
Authors: Taylor Peter , Turok Ivan , Hastings Annette
Published: August 2002

During the 1990s competitive bidding became the principal way of allocating resources for urban regeneration. One of the objectives was to invigorate the approach of local authorities by exposing them to the pressure of competition. Another was to open up decisionmaking to a wider spectrum of interests, including the private sector and local communities. The authors examine the consequences for unsuccessful areas—an analysis which is crucial to any overall assessment of the approach. They focus on the competition for Priority Partnership Area status associated with the reshaping of Scotland's Urban Programme under Programme for Partnership. The analysis reveals a modest stimulus to partnership working in several areas, attributable to the need for agencies to cooperate in a time-constrained bidding process and to manage ‘compensation’ funds thereafter. These benefits were offset by the disillusionment caused by the experience and the penalties of losing resources. To avoid widening inequalities in the future, the authors argue, central government must recognise the impact of this disillusionment through improvements in the organisation of competitive bidding and through planning mechanisms for the mitigation of the adverse effects of losing.
Why People Say Where They are during Mobile Phone Calls
Authors: Laurier Eric
Published: August 2002

An often-noticed feature of mobile phone calls is some form of ‘geographical’ locating after a greeting has been made. The author uses some singular instances of mobile phone conversations to provide an answer as to why this geolinguistic feature has emerged. In an examination of two real cases and a vignette, some light is shed on a more classical spatial topic, that of mobility. During the opening and closing statements of the paper a short critique is put forward of the ‘professionalisation’ of cultural studies and cultural geography and their ways of theorising ordinary activities. It is argued that a concern with theory construction effectively distances such workers from everyday affairs where ordinary actors understand in practical terms and account competently for what is going on in their worlds. This practical understanding is inherent in the intricacies of a conversational ‘ordering’, which is at one and the same time also an ordering of the times and spaces of these worlds. By means of an indifferent approach to the ‘grand theories’ of culture, some detailed understandings of social practices are offered via the alternatives of ethnomethodological and conversational investigations.
Sampling and the Politics of Representation in US Census 2000
Authors: Hannah Matthew G
Published: August 2002

Counting of people in official censuses and other social surveys produces representations that are arguably of far greater political importance than the representations produced by voting. The recent controversy around the use of sampling methods in US Census 2000 illustrates some important political-geographical dimensions of our decisions regarding whether and how to be counted in surveys. The argument is intended both to illuminate political features of this very important source of geographical data and to encourage a more self-consciously political engagement with the statisitical surveys through which modern citizens more or less consciously contribute to the shaping of our own lives.
Multiple Regression and Spatial Policy Analysis: George Udny Yule and the Origins of Statistical Social Science
Authors: Hepple Leslie W
Published: August 2002

Studies on the history of statistics by MacKenzie and on quantitative geography by Barnes have suggested that the lineaments and assumptions of statistical methods such as correlation and regression are closely related to their origin in biometrics and eugenics. This paper challenges that view by examining in detail the work of George Udny Yule. Yule was a colleague of Karl Pearson in the 1890s, but was interested in social science and social policy applications, not eugenics. In the late 1890s he constructed both the theory and application of multiple regression analysis, using geographical data. The paper examines Yule's work and its context, relating it to debates on the history of statistics, and traces the subsequent early diffusion of regression and correlation into the social sciences. The paper concludes by arguing for greater recognition of Yule's pivotal role, and also for further studies on the history of quantitative social science.
High-Spatial-Frequency Tritanopia: S-Filling-in or S-Filtering-Out?
Authors: Logvinenko Alexander D
Published: August 2002

It has long been an accepted fact that a small test field presented against a large background may change its colour appearance because the test-field background contrast is attenuated by the receptor colour channels unequally (Willmer, 1944 Nature153 774–775; Hartridge, 1947 Philosophical Transactions of the Royal Society of London, Series B232 519–671). Such an effect is usually called small-field tritanopia. However, as shown in the present report, a similar colour illusion can be achieved with a large test field as well, provided its spatial-frequency content is high enough to reveal the differential drop of contrast sensitivity for the receptor colour channels (high-spatial-frequency tritanopia). A few demonstrations are presented which show that a traditional explanation of high-spatial-frequency tritanopia (including small-field tritanopia), based on the hypothetical process of filling-in, is not correct. An alternative account, based on spatial filtering within the receptor colour channels, is put forward.
Route Navigating without Place Recognition: What is Recognised in Recognition-Triggered Responses?
Authors: Mallot Hanspeter A , Gillner Sabine
Published: August 2002

The use of landmark information in a route-navigation task has been investigated in a virtual environment. After learning a route, subjects were released at intermediate points along the route and asked to indicate the next movement direction required to continue the route. At each decision point, three landmarks were present, one of which was viewed centrally and two which appeared in the periphery of the visual field when approaching the decision point. In the test phase, landmarks could be replaced either within or across places. If all landmarks combined into a new place had been associated with the same movement direction during training, subjects performed as in the control condition. This indicates that they did not need to recognise places as configurations of landmarks. If, however, landmarks that had been associated with conflicting movement directions during training were combined, subjects' performance was reduced. We conclude that local views and objects are recognised individually and that the associated directions are combined in a voting scheme. No evidence was found for a recognition of places as panoramic views or configurations of objects.
Detection of Bilateral Symmetry in Complex Biological Images
Authors: Evans Christopher S , Wenderoth Peter , Cheng Ken
Published: August 2002

The recognition of bilateral symmetry in simple dot patterns is reliably influenced by orientation. Performance is best when the axis of symmetry is vertical. We conducted two experiments to determine whether stimulus orientation also affects detection of the low levels of naturally occurring asymmetry in complex biological images. University students judged whether colour images displayed on a computer monitor possessed perfect bilateral symmetry. Stimuli were generated from high-resolution plan-view images of crabs and insects. In experiment 1, the asymmetric stimuli were the original animals, displayed on a standard black background. Symmetrical versions of each natural image were generated by sectioning the shape at the midline, copying and reflecting one side, and then fusing the two halves together. To facilitate comparison of results with those obtained in earlier studies, we also presented dot patterns based upon both the slightly asymmetric and perfectly symmetrical natural images. Experiment 2 was designed to assess whether symmetry detection was dependent upon the markings and patterns on the body and appendages of the animals. The natural images were converted to silhouettes and tested against matched dot patterns. In both studies, images were presented in a random sequence with the axis of symmetry vertical, horizontal, oblique left, and oblique right. Performance with the biological images was consistently better than with the dot patterns. Abolishing fine detail did not appreciably reduce this effect. A pronounced vertical advantage was apparent with all stimuli, demonstrating that this phenomenon is robust despite considerable variation in image complexity. The implications of orientation effects for perception of natural structures are discussed.
What Does Second-Order Vision See in an Image?
Authors: Schofield Andrew J
Published: August 2002

The human visual system is sensitive to both first-order variations in luminance and second-order variations in local contrast and texture. Although there is some debate about the nature of second-order vision and its relationship to first-order processing, there is now a body of results showing that they are processed separately. However, the amount, and nature, of second-order structure present in the natural environment is unclear. This is an important question because, if natural scenes contain little second-order structure in addition to first-order signals, the notion of a separate second-order system would lack ecological validity.

Two models of second-order vision were applied to a number of well-calibrated natural images. Both models consisted of a first stage of oriented spatial filters followed by a rectifying nonlinearity and then a second set of filters. The models differed in terms of the connectivity between first-stage and second-stage filters. Output images taken from the models indicate that natural images do contain useful second-order structure. Specifically, the models reveal variations in texture and features defined by such variations. Areas of high contrast (but not necessarily high luminance) are also highlighted by the models. Second-order structure—as revealed by the models—did not correlate with the first-order profile of the images, suggesting that the two types of image ‘content’ may be statistically independent.
The Discrimination of Dog Odours by Humans
Authors: Wells Deborah L , Hepper Peter G
Published: August 2002

The domestic dog is able to identify both individual conspecifics, ie other dogs, and individual interspecifics, eg humans, by smell. Whilst humans can recognise individual members of their own species using olfactory information, it is unknown whether they can identify members of any other species in this manner. We examined the ability of humans to identify individual dogs by smell. Twenty-six dog owners were required to smell two blankets, one impregnated with the odour of their own dog, the other impregnated with the odour of an unfamiliar dog. Participants were required to indicate which of the odours smelt the strongest, which smelt the most pleasant, and which of the odours belonged to their own dog. Most of the participants (88.5%) were able to recognise the odour of their own dog. They showed no significant bias, however, in responding which of the odours they thought smelt the strongest or most pleasant. The results indicate that dogs produce odours that are individually distinctive to their owners, and highlight the fact that humans can recognise members of another species using olfactory cues—an ability presumably acquired without conscious effort.
Comparing Contrast-Modulated and Luminance-Modulated Masking: Effects of Spatial Frequency and Phase
Authors: Willis Alexandra , Smallman Harvey S , Harris Julie M
Published: August 2002

The masking of a sinusoidal test grating by contrast-modulated (CM) gratings could, in principle, be attributable to the presence of a distortion product, injected into the stimulus during some nonlinear transformation at an early level of visual processing (eg Nachmias, 1989 Vision Research29 137 – 142). If so, CM gratings and luminance-modulated (LM) gratings of similar effective contrast and spatial frequency should mask the detection of sinusoids in a similar fashion. We compared the effects of masking by 1 cycle deg−1 CM gratings [both simple beats (8 + 9 cycles deg−1) and amplitude-modulated gratings (8 + 9 + 10 cycles deg−1)], with those of masking by 1 cycle deg−1 LM gratings of low contrast. We found that: (i) CM and low-contrast LM grating masks yielded similar spatial-frequency tuning functions around the modulation frequency of 1 cycle deg−1; (ii) low-contrast LM gratings masked the detection of test sinusoids in a highly phase-dependent fashion, while masking by CM gratings did not vary systematically with relative spatial phase. The results suggest that masking produced by CM gratings cannot simply be explained by the presence of a distortion product at the beat or modulation frequency.
Adventures with Gelatinous Ellipses—Constraints on Models of Human Motion Analysis
Authors: Weiss Yair , Adelson Edward H
Published: August 2002

An ellipse rotating rigidly about its center may appear to rotate rigidly or to deform nonrigidly so that it appears gelatinous. We use this ambiguous stimulus to study how motion information is propagated across space. We find that features that are quite far from the contour of the ellipse may have a strong influence on the percept of the ellipse, provided they move in a way consistent with the motion of the ellipse. We show that the percept cannot be accounted for by computational models that pool constraints over a local area only, or by models that propagate information along contours, or by models that indiscriminately propagate information across space. However, the percept can be accounted for by a class of models that assume smoothness in a layered representation.
Cavanagh and Leclerc Shape-From-Shadow Pictures: Do Line Versions Fail Because of the Polarity of the Regions or the Contour?
Authors: Kennedy John M , Bai Juan
Published: August 2002

Shape-from-shadow perception fails when the contour bordering a shadowed area is reduced to a black line, and the shadow area becomes white. It might be that the polarity of the shadowed and illuminated areas has to be from dark on the shadowed side to light on the illuminated side for successful perception. Or it may be that the line, which has two contours, has one too many for shape-from-shadow processing. Alternatively, the problem might be that one of the contours of the line is incorrectly polarised. To test these explanations, three shape-from-shadow figures were prepared, each depicting the same referent—an elderly person. All three figures had two correctly polarised areas. One figure had a correctly polarised contour at the border between the areas. One had two correctly polarised contours. The other had one correctly polarised contour and one incorrectly polarised contour. The referent of the figure with one incorrectly polarised contour was the one difficult to make out. The result has implications for several theories, including an account of a demonstration by Hering involving penumbra.
Luminance Determinants of Perceived Surface Stratification in Two-Dimensional Achromatic Transparent Patterns
Authors: Masin Sergio Cesare
Published: August 2002

Two overlapping transparent surfaces forming a two-dimensional pattern stand out in front of each other alternately. Let y denote the luminance of the region where these surfaces overlap and b the luminance of the background. In achromatic patterns, the probability that the lighter transparent surface appears to be in front of the other surface is known to increase with y and with b. The present results show that grouping by achromatic colour similarity cannot explain the effect of b. An alternative conjecture is that the luminance factors that control perceived surface segregation can explain the effects of y and b. Such an explanation predicts a new effect: the probability that one transparent surface appears to be in front increases with the absolute difference in luminance between the surface and the background. The present results confirm this prediction.
Recognising the Style of Spatially Exaggerated Tennis Serves
Authors: Rollick Frank E , Fidopiastis Cali , Braden Vic
Published: August 2002

A technique for the construction of exaggerated human movements was developed and its effectiveness tested for the case of categorising tennis serves as flat, slice, or topspin. The technique involves treating movements as points in a high-dimensional space and uses average movements as the basis for constructing exaggerated movements. Exaggerated movements of a particular style are defined as those points in the space of movements which lie on a line originating at the style average and in the direction defined by the difference between the style average and the grand average. In order to visualise the movements, computer animation techniques were employed to transform the three-dimensional coordinates of the movement into the motion of a solid-body figure. These solid-body models were used in perceptual experiments to assess the effectiveness of the exaggeration technique. After an initial training session on the exemplars from the original library, subjects viewed the synthetic tennis-serve motions and in two separate sessions either made three-alternative, categorisation judgments after viewing a single serve or rated dissimilarity after viewing a pair of serves. Results from both accuracy in the categorisation task and structure of a multidimensional scaling solution of the matrix of dissimilarities indicated that, as distance from the grand average increased, the service motion became more distinct and more accurately identified.
Perceptual Continuation and Depth in Visual Phantoms can Be Explained by Perceptual Transparency
Authors: Kitaoka Akiyoshi , Gyoba Jiro , Kawabata Hideaki , Sakurai Kenzo
Published: August 2002

We try to explain perceptual continuation and depth in the visual-phantom illusion in terms of perceptual transparency. Perceptual continuation of inducing gratings across the occluder in stationary phantoms could be explained with unique transparency, a notion proposed by Anderson (1997 Perception26 419–453). This view is consistent with a number of previous reports including that of McCourt (1994 Vision Research34 1609–1617) who criticized the stationary phantom illusion from the viewpoint of his counterphase lightness induction or grating induction, which might involve invalid transparency. Here we confirm that the photopic phantom illusion (Kitaoka et al, 1999 Perception28 825–834) really gives in-phase lightness induction and involves bistable transparency. It is thus suggested that perceptual continuation and depth in the visual-phantom illusion depend on perceptual transparency.
Adaptation Reveals a Neural Code for the Visual Location of Orientation Change
Authors: Prins Nicolaas , Mussap Alexander J
Published: August 2002

We apply an adaptation technique to explore the neural code for the visual location of textures defined by modulation of orientation over space. In showing that adaptation to textures modulated around one orientation shifts the perceived location of textures modulated around a different orientation, we demonstrate the existence of a neural code for the location of orientation change that generalises across orientation content. Using competitive adaptation, we characterise the neural processes underlying this code as single-opponent for orientation, that is with concentric excitatory/inhibitory receptive areas tuned to a single orientation.
‘Perceiving the Present’ as a Framework for Ecological Explanations of the Misperception of Projected Angle and Angular Size
Authors: Changizi Mark A
Published: August 2002

An implicit, underlying assumption of most Helmholtzian/Bayesian approaches to perception is the hypothesis that the scene an observer perceives is the probable source of the proximal stimulus. There is, however, a nontrivial latency (on the order of 100 ms) between the time of a proximal stimulus and the time a visual percept is elicited. It seems plausible that it would be advantageous for an observer to have, at any time t, a percept representative of what is out there at that very time t, not a percept of the recent past. If this is so, it implies a modification to the implicit hypothesis underlying most existing probabilistic approaches to perception: the new hypothesis is that, given the proximal stimulus, the scene an observer perceives is the probable scene present at the time of the percept. That is, the hypothesis is that what an observer perceives is not the probable source of the proximal stimulus, but the probable way the probable source will be when the percept actually occurs. A model of an observer's typical movements in the world is developed, and it is shown that projected angles are perceived in a way consistent with the way the probable source will project to the eye after a small time period of forward movement by the observer. The predicted and actual direction of projected-angle misperception is sometimes toward 90° and sometimes away from 90°, depending on whether the probable source angle is lying in a plane parallel or perpendicular to the probable direction of motion, respectively. The perception of angular size for lines in a figure with cues they are lying in a plane perpendicular to the direction of motion is also shown to fit the predictions of the model.
Multistability of Overlapped Face Stimuli is Dependent upon Orientation
Authors: Boutet Isabelle , Chaudhuri Avi
Published: August 2002

Stimuli composed of two overlapped faces, one rotated 45° clockwise and the other 45° counterclockwise, produce perceptual rivalry whereby both faces cannot be simultaneously perceived. We obtained subjective and quantitative measures of this rivalry effect and examined if it persists with inverted stimuli. Our results show that upright stimuli are multistable, with alternations occurring from one face to the other within 2 s. Inverted stimuli were instead perceived as ambiguous in half of the trials, indicating weaker perceptual rivalry in that condition. We suggest that overlapped faces produce perceptual rivalry because each face is readily interpreted into a Gestalt, an effect that in turn is dependent upon orientation.
Independent Detectors for Expansion and Rotation, and for Orthogonal Components of Deformation
Authors: Meese Tim S , Harris Mike G
Published: August 2002

It is well known that optic flow—the smooth transformation of the retinal image experienced by a moving observer—contains valuable information about the three-dimensional layout of the environment. From psychophysical and neurophysiological experiments, specialised mechanisms responsive to components of optic flow (sometimes called complex motion) such as expansion and rotation have been inferred. However, it remains unclear (a) whether the visual system has mechanisms for processing the component of deformation and (b) whether there are multiple mechanisms that function independently from each other. Here, we investigate these issues using random-dot patterns and a forced-choice subthreshold summation technique. In experiment 1, we manipulated the size of a test region that was permitted to contain signal and found substantial spatial summation for signal components of translation, expansion, rotation, and deformation embedded in noise. In experiment 2, little or no summation was found for the superposition of orthogonal pairs of complex motion patterns (eg expansion and rotation), consistent with probability summation between pairs of independent detectors. Our results suggest that optic-flow components are detected by mechanisms that are specialised for particular patterns of complex motion.
Mental Models of Line Drawings
Authors: Burns Kevin J
Published: August 2002

Mental models are internal representations of world structure, used to accomplish cognitive tasks. I postulate specific representations (of objects and images) and associated context (of world and view) for mental models of line drawings. I then analyze the representations and context to predict specific perceptual modes, including the relative strengths of these modes. The predicted modes are supported by a well-known example [from Rock, 1983 The Logic of Perception (Cambridge, MA: MIT Press)] where object perception changes with image orientation.
Photoprotection in water-stressed plants of durum wheat (Triticum turgidum var. durum): changes in chlorophyll fluorescence, spectral signature and photosynthetic pigments
Authors: Tambussi Eduardo A. , Casadesus Jaume , Munné-Bosch Sergi , Araus José Luis
Published: August 2002

We analysed the photoprotective response in water-stressed plants of durum
wheat (Triticum turgidum L. var.
durum cv. Mexa). The plants were grown in a greenhouse
for 4 weeks and then exposed to water stress by withholding water for 8 d.
Development of water stress was monitored as the decrease in relative water
content (RWC) and net CO2 assimilation of the last fully
developed leaf. The photoprotective response was evaluated in the same leaves
by analysing modulated chlorophyll fluorescence, leaf spectroradiometrical
changes, and pigment content. Measurements were performed 3, 6 (moderate
stress) and 8 (severe stress) d after water-stress treatment began. The
non-photochemical quenching of chlorophyll fluorescence (qN), as well as the
contents of zeaxanthin and antheraxanthin increased significantly after 6 d of
treatment. However, a further rise in these xanthophylls on day 8 was not
associated with any increase in qN. In addition, the β-carotene content
rose significantly on day 8, suggesting an increase in antioxidant defences.
The photochemical index (PI), derived from spectroradiometrical measurements,
showed a strong progressive drop on days 6 and 8, which was paralleled by an
increase in the de-epoxidation state of the xanthophyll cycle (DPS), in
particular by the zeaxanthin content. At midday, PI was strongly (negatively)
correlated with DPS and qN. These results suggest that the PI may be a
reliable indicator of photoprotection in the study of plant stress, and in
breeding programs.
Fundamentals of Magnetorheological Fluid Utilization in High Precision Finishing
Authors: Kordonski W. I. , Golini D.
Published: August 2002

Magnetorheological finishing (MRF) is an enabling technology that may produce surface accuracy on the order of 30 nm peak to valley (p-v) and surface micro-roughness less than 10 A rms. In MRF, mechanical energy for material removal over the portion of the workpiece surface is generated by the magnetically controlled hydrodynamic flow of a magnetorheological polishing fluid. A fundamental advantage of MRF over existing technologies is that the polishing tool does not wear, since the recirculated fluid is continuously monitored and maintained. Polishing debris and heat are continuously removed. The technique requires no dedicated tooling or special setup.

A unique attribute of the MRF process is its determinism that is attained through the use of a well-defined material removal function to eliminate known surface error.

The efficiency of material removal and the removal process stability are the crucial factors in MRF. In turn, they are primarily dependent on MR polishing fluid stability. It is shown that the joint use of physicochemical and rheological factors along with specially developed methods of the slurry handling, pumping, and in-line monitoring and maintaining provides a level of MR slurry stability that is quite adequate for high precision finishing. Attention is given to methods of MR slurry property measurements.
Application of Neural Networks to Defect Detection in Cantilever Beams with Linearized Damage Behavior
Authors: Kawiecki Grzegorz
Published: August 2002

This paper shows the feasibility of using a very simple feed-forward backpropagation neural network for fast and accurate estimation of the location and size of a crack in a cantilever beam. The presented network is trained and tested using data generated by a linear, closed-form, one-dimensional theoretical model of the cracked beam. It is shown that the neural network is a very attractive alternative to presently used methods.
Modal Vibration Control for PVDF Coated Plates
Authors: Stöbener Uwe , Gaul Lothar
Published: August 2002

Since advanced technical systems, such as aircrafts, space structures and automobiles, have to combine high performance with low weight, passive vibration absorbers reach their limits. This is why active control has become more important in structural dynamics with successful applications. Vibration control requires sensors, actuators and a controller. In this paper Polyvinylidene fluoride (PVDF) is used as actuator and sensor material. The PVDF elements are segmented in arrays on the plate. The sensors act as point sensors and the sensor signals are filtered by a modal sensor matrix. The modal displacements and modal velocities are used as input data for the controller and for a so-called Actuator Management System (AMS) as well. A modal actuator matrix transforms the controller output into driving actuator voltages. The AMS switches elements of the modal actuator matrix which results in quasi modal actuator groups. A rectangular aluminum plate has been equipped with PVDF actuators and sensors and experimental tests have been carried out in order to validate the proposed concept.
Flame Behavior of Cotton Coated with Polyurethane Containing Microencapsulated Flame Retardant Agent
Authors: Giraud StéPhane , Bourbigot Serge , Rochery Maryline , Vroman Isabelle , Tighzert Lan , Delobel René
Published: August 2002

Polyurethane-phosphates combination is known to form flame retardant (FR) intumescent system. But the intumescent formulation could not be permanent because of the water solubility of the phosphate. This problem could be solved by the technique of microencapsulation. Microcapsules of di-ammonium hydrogen phosphate (DAHP) with a polyurethane (PU) shell were synthesized. Chemical and physical structure of the DAHP microcapsules were characterized. Cotton fabrics were coated with polyurethane (PU) coating including neat DAHP or encapsulated DAHP. The flame retarding behavior of these coated cotton fabrics was valued with the cone calorimeter. This new concept of phosphate encapsulated by PU shell showed a significant FR effect.
Eigenstrain Techniques for Modeling Adaptive Structures. I: Active Stiffness Tailoring
Authors: Alghamdi Abdulmalik A. A. , Dasgupta Abhijit
Published: August 2002

Three-dimensional eigenstrain techniques are used in this paper to model mechanical interactions in an active structure containing small embedded sensors and actuators. Eigenstrain techniques are used to predict the state of the strain inside the devices (sensors and actuators) under external and internal loads. The elastic energy of the structure is written in terms of the strain inside the devices, and an analytical dynamic model is developed based on a generalized form of Hamilton’s variational principle. As an example, the dynamic response of an active cantilever beam containing embedded mini-devices is investigated analytically and experimentally. Specifically, active stiffness tailoring capabilities are explored. An analytical solution to the variational problem is obtained by using the Raleigh-Ritz approach. A numerical example is given and the response of the active structure is verified experimentally, using a cantilever beam made of Alplex plastic as host material and piezoelectric (PZT-5H) devices as active mini-devices for sensing and actuation. The analytical results show reasonable agreement with the experimental observations.
Micromechanics Based Composite Material Model for Crashworthiness Explicit Finite Element Simulation
Authors: Tabiei Ala , Chen Quing
Published: August 2002

A micromechanical model is developed for laminated composite materials and implemented in the explicit finite element method. The objective of this study is to get an accurate and simple micro-model that can be used in the displacement-based nonlinear explicit finite element code DYNA3D. The micromechanical model implemented in the explicit finite element code can be used for simulating the behavior of composite structures under various loads such as impact and crash. The stress-strain relation for the micro-model is derived for shell element. A micro-failure criterion (MFC) is presented for each material constituent and failure mode. The implemented model is validated through several test examples. As a demonstration case of the stability of the developed micro-model, a finite element model of a graphite/epoxy tube structure is developed and simulated under axial crash.
Instrumented Perforation Impact Response of Polypropylene Composites with Hybrid Reinforcement Flax/Glass and Flax/Cellulose Fibers
Authors: Benevolenski O. I. , Karger-Kocsis J. , Mieck K. -P. , Reubmann T.
Published: August 2002

The transverse perforation impact behavior of flax mat-reinforced polypropylene (PP) composites with additional discontinuous cellulose (LyocelliTM, L) and discontinuous glass (G) fiber mat was investigated at a constant reinforcement content (50 wt.%). The resistance to perforation impact of the PP/flax composite was strongly improved by the hybridization with L and G fibers. Enhanced resistance to perforation impact of the hybridized composites was also reflected in the Charpy impact strength values. This improvement was attributed to an enhanced strength, which affected the overall failure behavior as well. The failure mode was inspected in scanning electron microscopy (SEM) and discussed.
Modeling the Effects of Reinforcements on the Crystallization of Polymers
Authors: Bénard André
Published: August 2002

An approach for modeling the isothermal crystallization of reinforced polymers is presented. It is based on the classical phase change model of Avrami and uses expressions for the volume of intersection between the spherulites and the reinforcements. The cases of cylindrical (fibers) and spherical (particles, bubbles) inclusions are particularly of interest, since they are encountered in a variety of composites. The evolution of the crystallinity can be computed for various nucleation processes. The effects of surface-nucleated spherulites on the overall crystallization process can also be incorporated and the influence of parameters such as the reinforcement volume fraction and radius and the nucleation density are also discussed.
Stress Spectra and the Effective Elastic and Viscoelastic Properties of Unidirectional Composites under Transverse Loading
Authors: Kim Patrick , Toll Staffan
Published: August 2002

The relationship between the statistical characteristics of the microstructure, the stress state in the matrix and the effective properties of unidirectional composites have been studied. A representation of the stress state in the form of stress spectra is introduced. The skewness of spectra derived for the four basic regular periodic fiber arrays reflects the degree of order in the microstructure. A hybrid array combining features of these arrays was developed to approximate a random array. All stress components in the matrix of such a pseudo-random composite under transverse load exhibit an approximately Gaussian distribution. The stress state in the matrix determines the effective elastic modulus and the viscoelastic relaxation strength. This has led to a stress-based mechanical analysis using the moments of the stress spectrum for a representative, pseudo-random fiber arrangement.
Analysis of Dynamic Surface Properties of Therapeutic Surfactants and Lung Phospholipids
Authors: Banerjee R. , Puniyani R. R. , Bellare Jayesh R.
Published: August 2002

Exogenous surfactant is a specialized biomaterial used for substitution of the lipoprotein mixture normally present in lungs-pulmonary surfactant. Respiratory Distress Syndrome is a disease of preterm infants mainly caused by a deficiency of mature lung surfactant. Pulmonary surfactant is known to stabilize small alveoli and prevent them from collapsing during expiration due to its unique surface properties. A pulsating bubble surfactometer was used for in vitro analysis of surface parameters of therapeutic surfactants and of test formulations to be used for exogenous therapy in Respiratory Distress Syndrome. Surface parameters that were considered for comparison were minimum surface tension (γmin) at three different frequencies (20,40 and 60 cpm), adsorption at two extreme bubble radii ( Rmin and Rmax), stability index at the three frequencies, recruitment index and the surface viscoelastic parameters. Survanta, ALEC and Exosurf were compared with formulations consisting of the main phospholipids of pulmonary surfactant, namely dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) as well as binary mixtures of these phospholipids in the ratio 2:3. Survanta performed much better than the non-protein therapeutic surfactants in all parameters and at all three frequencies. Exosurf had a very low stability index and a very low modulus of surface dilatational elasticity at all three frequencies. The test compounds showed a frequency dependence in their performance. At 20 cpm, PC:PG (2:3) was the best test combination. It achieved a γmin and stability index equivalent to Survanta at this frequency. None of the test compounds were comparable to Survanta at 40 and 60 cpm. These findings may have important therapeutic implications for exogenous surfactants.
The Year in Review: Critical Care Medicine
Authors: Rudis Maria I. , Hoang David Q.
Published: August 2002

Background: There have been significant recent advances in the pharmacotherapeutic management of critically ill patients. The purpose of this article is to review and discuss the most pertinent published literature in the areas of neurology, cardiovascular diseases, infectious diseases, nephrology, hematology, and gastroenterology as it pertains to critical care in order to provide an update for the critical care practitioner.

Methods: We performed a Medline search from July 1999 to December 2000 utilizing terms relating to the pharmacotherapy of the specific aforementioned topics in critical care medicine. We focused on English-language clinical studies performed in adult intensive care unit (ICU) patients. From these articles we selected those that would have a practical impact on drug therapy in the ICU or the development of drug usage guidelines for critically ill patients. Review articles were generally not included.

Results: The following topics were found to be either new developments or of potentially significant impact in the management of adult critically ill patients. In the area of neurology, advances were found with respect to optimization of regimens for sedative and neuromuscular blocking agents, validation of sedation scales and tools, and in the treatment of head injury patients. In the cardiovascular diseases, most studies related to the hemodynamic support of septic shock. We focus on developments in fluid resuscitation, optimization of global and regional oxygen transport variables, the repositioning of vasopressor agents, and a return to the use of steroids. Given the high mortality rate associated with the development of acute renal failure in the ICU, there has been a consistent attempt to develop preventative and treatment strategies for these patients, including optimization of antimicrobial dosing methods. Several epidemiological and longitudinal studies document changes in multi-drug antimicrobial resistance patterns. The use of treatment guidelines for antimicrobials in the critically ill improves outcomes in most patients. Significant attention has focused on the characterization of anemia in the ICU and the development of alternative pharmacological strategies in its treatment. Finally, in gastroenterology, the main focus has been the investigation of methods to optimize the delivery of enteral nutrition given its proven benefits in critically ill patients.

Conclusions: Significant advances in the areas of neurological, cardiovascular, infectious diseases, renal, hematological, and gastrointestinal issues in the pharmacotherapy of critically ill patients have been published over the course of the past year. Many of these studies have yielded data that may be incorporated into the pharmacotherapeutic management of ICU patients, hence maximizing outcomes.
A Shape Memory Alloy Actuator Using Peltier Modules and R-Phase Transition
Authors: Luo Yun , Takagi Toshiyuki , Maruyama Shigenao , Yamada Makoto
Published: August 2002

This paper describes the development of a novel shape memory alloy (SMA) actuator with high frequency responses. By applying Peltier modules as heat pumps for heating and cooling of SMAs, the actuator is expected to have higher frequency responses comparing with conventional ones. Thermomechanical properties of the actuators; such as the deformation of SMAs and recovery forces generated during the phase transition of SMAs, were investigated first. Then, response tests of the actuators were carried out in the complete thermal cycles for cases with and without Peltier modules respectively. Based on results from numerical simulations and experiments, the transient behavior of the actuator subjected to continuous actuations has been discussed. The results show that the actuator has dramatically enhanced frequency responses. In cases where the heating and cooling are controlled by electric current sequences, the thermal instability of the actuator occurs due to the accumulation of Joule heat in Peltier modules. Therefore, a proportional plus integral plus derivative (PID) action is employed to control the temperature of the SMA, it leads to the stable actuations with the frequency responses up to 0.5 Hz.