bluuebunny/crossref_metadata_2025 huggingface dataset:
Contact problems in the design of a superconducting quadrupole prototype
Authors: Blanzé Claude , Champaney Laurent , Vedrine Pierre
Published: July 2002

This paper focuses on the design of a superconducting quadrupole prototype. This structure includes many frictional contact zones, and the loading conditions are complex (mechanical, thermal and magnetic). A dedicated computational strategy, based on both a decomposition of the structure and an iterative resolution scheme, has been applied to solve this problem. A simplified approach is used to take complex loading conditions into account. The initial set of results, which are presented herein, demonstrates the interest of this approach with respect to classical finite element methods. This study was conducted within the framework of a joint research contract between the CEA (DSM/DPANIA/STCM) and LMT‐Cachan.
Using a business simulation to teach applied skills – the benefits and the challenges of using student teams from multiple countries
Authors: Doyle Declan , Brown F. William
Published: July 2002

The Business Strategy Game is a PC‐based simulation that gives the players experience in developing and implementing strategies. The students run their company in a competitive market setting against other teams. This forces them to take risks and anticipate competitor strategies. This paper is based on an international simulation game involving five teams of postgraduate business students from universities in Ireland, France and the US. The game was run in a “virtual environment” using e‐mail and videoconferencing. The attempt was made to simulate realistic competitive conditions as much as possible so that the concepts learned and solutions generated could be transferred from the classroom to the outside business environment.
What should training evaluations evaluate?
Authors: Mann Sandi
Published: July 2002

Training initiatives are widely acknowledged to be a salient feature of the competitive organization’s corporate strategy. Contends that, despite the heavy investment in training, organizations frequently fail to evaluate adequately the value or success of their training programmes. Those companies which do evaluate often use measures considered ineffective by many researchers. Part of the reason for companies’ reluctance to evaluate their training may be confusion as to how and what to evaluate. Reviews some of the barriers to effective training evaluation and outlines the benefits that organizations which do evaluate can invite. Describes the results and implications for organizations of a study undertaken in Europe to answer the question: “What should training evaluations evaluate?” Concludes that neither reactions to training nor immediate post‐training knowledge are predictors of subsequent self‐efficacy (an established indicator of actual performance).
Outdoor management development: use and evaluation
Authors: Badger Beryl , Salder‐Smith Eugene , Michie Edwin
Published: July 2002

Reviews the use of and evaluations of OMD by a number of large employers and suggests a framework for the evaluation of outdoor management development (OMD). In a questionnaire survey of large organizations it was found that current users of OMD feel that it is an effective part of their management development programmes and that these firm beliefs in the benefits for personal, team and leadership development are used as justification to continue to use the outdoors as a medium for enhancing their management development programmes. What was not clear was how such conclusions were arrived at other than through anecdote and intuition. Argues that more detailed systematic research using a range of techniques is required in order to investigate the claims of current users and the views of non‐users.
The effects of filler materials on poly(vinyl acetate) emulsion wood adhesives
Authors: Qiao Lijun , Easteal Allan J. , Bolt Clive J. , Coveny Philip K. , Franich Robert A.
Published: July 2002

Fillers with different chemical properties were used to study their effects on poly(vinyl acetate) (PVAc) emulsion wood adhesives. The elastoplastic behaviour of the filler treated PVAc emulsions was studied using differential scanning calorimetry and dynamic mechanical thermal analysis. The results show that the glass transition temperature (Tg) of the polymer is not changed significantly by the addition of the fillers, while the tensile modulus is changed together with the hardness and stiffness. The viscosity of the emulsions and their performance on wood surfaces are greatly affected by fillers. Fillers with high oil‐absorption capacity increase viscosity to a greater extent. The acidity of the fillers influences the setting time for bonding of the emulsions to wood, and the water resistance, since some chemical reactions can take place during curing.
Environmental scanning in educational organizations: uses, approaches, sources and methodologies
Authors: Pashiardis Petros
Published: July 2002

Suggests that, in today’s world of uncertainty, it is of vital importance for an individual or an educational institution to stay abreast of environmental changes which may affect their future. Presents up‐to‐date information on environmental scanning and how it can be used to benefit educational organizations. For modern educational institutions, it is necessary to establish a systematic method of collecting information regarding external influences on educational institutions. However, it is quite difficult for any individual to be knowledgeable about all occurrences that may affect an institution, and it often requires special expertise to realize how an event or trend might affect an institution in the future. An institution must tailor specific sources of external information, devise a method to collect the information, and use the information effectively in the planning process and in building the future. Argues that environmental scanning has proved to be successful for school systems and should be accorded the importance it deserves. Furthermore, scanning provides all individuals with the opportunity to contribute to the strategic planning process which is of vital importance for the survival of an organization.
Teachers’ perceptions of school quality and effectiveness: improving schools using staff attitude surveys
Authors: Davies Brent , Ellison Linda
Published: July 2002

Focuses on school staff as part of the authors’ work involving surveys of pupils, parents and staff in a range of school planning and improvement strategies. Believes there is a danger that assumptions will be made about what staff think of the school. It is important to have mechanisms to gather genuine views rather than making such assumptions. An honest view of the staff’s perceptions of a school will provide significant information for school improvement. The authors worked with the schools and used a questionnaire approach. Questions were designed to be answered quite quickly but to cover a range of areas in‐depth. The 30 questions were randomized in the questionnaire but regrouped into categories for analysis. Discusses process issues such as the implementation of the survey and the follow‐up required in the school in terms of school planning and improvement.
Television without frontiers – can culture be harmonized?
Authors: Curwen Peter
Published: July 2002

There is constant tension within the EU arising from conflicting national interests. One aspect of this which has received little attention is that of conflicting national cultures. In the modern world, culture is mainly transmitted across national borders via the medium of television. This means that the USA, which produces the greater part of world output of TV material, would fill a majority of schedules outside the USA in a free market. Within the EU, some countries find this acceptable whereas others do not, fearing that their national cultures will be destroyed. These tend to be countries with a different language and a history of originating rather than receiving culture. The issue of how much culture can be imported has accordingly dogged the EU for a long period, resulting in many cases before the European Court of Justice and several unsatisfactory attempts to produce a universally acceptable directive on the issue of cross‐border TV.
Subjective and objective evaluation of men’s shirting fabrics
Authors: Lun Yick Kit , Cheng K.P.S. , Lai How Yan
Published: July 2002

Reports a survey of fabric handle preferences for a range of 50 men’s shirting materials. A total of 199 judges were divided into two panels according to their experience in the textile and clothing industry. Low levels of agreement were found which signify the errors inherent in subjective assessment of fabric handle. The analysis was extended to include fabric assurance by simple testing (FAST) data on the mechanical properties of these fabrics in order to establish whether there was any relationship existing between the judges’ preferences and the fabric mechanical parameters. Highlights shear rigidity, formability and bending rigidity as the most influential properties for the determination of fabric total hand value (THV). Moreover, establishes a validated THV equation to predict fabric handle assessment by using objective data. Demonstrates that the mean of the assessment and a substantial amount of individual subjective handle assessment can be explained by the model.
Application of cluster analysis to fabric classification
Authors: Chen Y. , Collier B.J. , Collier J.R.
Published: July 2002

This paper introduces a new way of classifying clothing fabrics objectively. Representative apparel fabrics were collected and measured by the Kawabata Evaluation System for Fabrics (KES‐FB). The disjoint clustering method was used to divide fabrics into four clusters, each representing particular fabric performance and end‐use characteristics. These classified clusters were further analyzed applying the method of principal‐component analysis to acquire factor patterns that indicate the most important fabric properties for characterizing different fabric end‐use. Extracted information from the instrumentally obtained data in terms of fabric physical properties is useful to fabric and garment producers, apparel designers, and consumers in specifying and categorizing fabric products, in insuring proper fabric use, and in controlling fabric purchase.
Sex, lies, and Hollywood’s administrators
Authors: Smith Penny
Published: July 2002

The author argues that messages about educational administrators found in contemporary films both shape and limit popular discourse about schools and their mission. Of particular importance is the dissonance between the celluloid images created by Hollywood and the complex and challenging realities found in our own communities. Based on a textual analysis of 28 recent productions, she argues that practitioners would do well to attend popular culture representations and to consider the ways in which mass media shape policy debates about public institutions and appropriate administrative behavior.
Retailing and risk society: genetically modified food
Authors: Pearce Richard , Hansson Maria
Published: July 2002

Examines the social environment experienced by UK food retailers regarding the marketing of genetically modified (GM) foodstuffs. Beck’s notion of risk society provides a critical foundation for analysing retail organisations’ decision making under conditions of “post‐Enlightenment contemporary irrationality”. He advocates “understanding and conceptualisation” of “… insecurities of the contemporary spirit …”, arguing of these that it is “… ideologically cynical to deny and dangerous to yield to uncritically”. The paper also draws upon Habermas, who describes three phenomena that sensitise “new social movements”; reactions to perceptions of “excessive complexity”; the apparent undermining of nature’s “organic foundations”; and a feeling of “overburdening or distortion” in “communicative infrastructures”. These dynamics should all inform any socially sensitive retailer response. The paper is not ethically prescriptive, but seeks to illustrate critically how conceptualisations of risk contribute to the social construction of ethical issues.
Academic regulation in UK higher education: part I ‐ the concept of collaborative regulation
Authors: Jackson Norman
Published: July 2002

The first of a series of three articles which map the dimensions and evolution of academic regulation in the UK. Argues that regulation is an important and substantial concept and set of activities which is far more comprehensive in scope and substance than the concept of quality assurance which it subsumes; that it involves the act of regulating (controlling and adjusting behaviour and practice against explicit or implicit rules) and the state of being regulated (practising within a framework of rules and accepted professional norms). Describes three basic types of regulatory regime ‐ self‐regulation, external regulation and mixed regimes ‐ and concludes that the size, complexity, diversity, history, public investment and interests in the UK higher education sector make it necessary to operate a mixed regime which incorporates elements of both external regulation and institutional self‐regulation. When viewed at the system level, the continuous interaction of external regulators with HE institutions, which have considerable autonomy over their internal regulatory mechanisms, is consistent with the concept of collaborative regulation (where co‐operation is both voluntary and mandatory).
EDI security: a model of EDI risks and associated controls
Authors: Ratnasingham Pauline
Published: July 2002

Defines the rationale for developing a model of EDl risks and associated controls. Highlights how and which EDI controls will alleviate and/or eliminate the specified EDI risks. The findings of the seven case studies identified additional EDI risks and controls, which paved the way for a new mapping of relationships between risks and controls. Offers a further insight into the perceptions of and responses to security threats faced by organizations in adopting EDI.
Decentralized cooperation: a distributed approach to team design in a concurrent engineering organization
Authors: Prasad Biren
Published: July 2002

A multi‐component design of a “concurrent team” is described here for a concurrent engineering organization. This concurrent “team design” is composed of four essential teaming components: a logical component, a virtual component, a technological component and a personnel (work‐group or humane) component. The description is based on an implementation of a “concurrent team” environment for product development at Delphi Divisions of General Motors. The paper first describes how to configure a “concurrent team” organization that provides a decentralized cooperation during an integrated product development (IPD) process. The paper then shows how, with strategic design of a “concurrent team,” an organization can achieve optimum teamwork productivity during an IPD. As it has been observed during a number of automotive projects that the teamwork productivity of a concurrent engineering organization is largely influenced by the design of such “concurrent teams” as well as by elements of decentralized cooperation, the paper, also describes four key elements of decentralized cooperation that have been found useful with IPD clients.
A new method for measuring signal integrity in CMOS ICs
Authors: Delmas‐Bendhia Sonia , Caignet Fabrice , Sicard Etienne
Published: July 2002

The aim of this paper is to present a new and original method for on‐chip measurements of very high frequency parasitic signals where a sampling circuit is directly included in the test chip. The paper describes the usefulness of this sensor for measuring signal propagation and cross‐talk glitch on integrated circuit interconnects and also gives the results obtained experimentally.
New product launch “mix” in growth and mature product markets
Authors: Hart Susan , Tzokas Nikolaos
Published: July 2002

This research examines whether the marketing mix decisions for new product launch change over the product‐market life cycle. Results raise questions about existing benchmark beliefs based on normative text‐book theories. In view of new insights we suggest a number of directions for the theoretical and empirical development of the new product launch field in the marketing management discipline.
Comparison of clinical indicators for performance measurement of health care quality: a cautionary note
Authors: Gross Peter A. , Braun Barbara I. , Kritchevsky Stephen B. , Simmons Bryan P.
Published: July 2002

The use of clinical performance data is increasing rapidly. Yet, substantial variation exists across indicators designed to measure the same clinical event. We compared indicators from several indicator measurement systems to determine the consistency of results. Five measurement systems with well‐defined indicators were selected. They were applied to 24 hospitals. Indicators for mortality from coronary artery bypass graft surgery and mortality in the perioperative period were chosen from these measurement systems. Analyses results and concludes that it is faulty to assume that clinical indicators derived from different measurement systems will give the same rank order. Widespread demand for external release of outcome data from hospitals must be balanced by an educational effort about the factors that influence and potentially confound reported rates.
Enzymatic conformational fluctuations along the reaction coordinate of cytidine deaminase
Authors: Noonan Ryan C. , Carter Charles W. , Bagdassarian Carey K.
Published: July 2002

Analysis of the crystal structures for cytidine deaminase complexed with substrate analog 3‐deazacytidine, transition‐state analog zebularine 3,4‐hydrate, and product uridine establishes significant changes in the magnitude of atomic‐scale fluctuations along the (approximate) reaction coordinate of this enzyme. Differences in fluctuations between the substrate analog complex, transition‐state analog complex, and product complex are monitored via changes in corresponding crystallographic temperature factors. Previously, we reported that active‐site conformational disorder is substantially reduced in the transition‐state complex relative to the two ground‐state complexes. Here, this result is statistically corroborated by crystallographic data for fluorinated zebularine 3,4‐hydrate, a second transition‐state analog, and by multiple regression analysis. Multiple regression explains 70% of the total temperature factor variation through a predictive model for the average B‐value of an amino acid as a function of the catalytic state of the enzyme (substrate, transition state, product) and five other physical and structural descriptors. Furthermore, correlations of atomic fluctuation magnitudes throughout the body of each complex are quantified through an auto‐correlation function. The transition‐state analog complex shows the greatest correlations between temperature factor magnitudes for spatially separated atoms, underscoring the strong ability of this reaction‐coordinate species to “organize” enzymatic fluctuations. The catalytic significance for decreased atomic‐scale motions in the transition state is discussed. A thermodynamic argument indicates that the significant decreases in local enzymatic conformational entropy at the transition state result in enhanced energetic stabilization there.
Characterization of Ad5 E3–14.7K, an adenoviral inhibitor of apoptosis: Structure, oligomeric state, and metal binding
Authors: Kim Hee‐Jung , Foster Mark P.
Published: July 2002

The adenovirus E3–14.7K protein, expressed early in the life cycle of human adenoviruses to protect the virus from the antiviral response of host cells, inhibits cell death mediated by TNF‐α and FasL receptors. To better understand its role in cell death inhibition, we have sought to characterize the biophysical properties of the protein from adenovirus serotype 5 (Ad5 E3–14.7K, or simply 14.7K) through a variety of approaches. To obtain sufficient quantities of recombinantly expressed protein for biophysical characterization, we explored the use of various expression constructs and chaperones; fusion to MBP was by far the most effective at generating soluble protein. Using limited proteolysis, mass spectrometry, and protein‐protein interaction assays, we demonstrate that the C‐terminal two‐thirds of the protein, predicted to be composed of five β‐strands and one α‐helix, is highly structured and binds its putative cellular receptors. Furthermore, using atomic absorption and ultraviolet/visible spectroscopies, we have studied the metal binding properties of the protein, providing insight into the observation that cysteine/serine mutants of 14.7K lack in vivo antiapoptotic activity. Lastly, results from size exclusion chromatography, dynamic light scattering, sucrose gradient sedimentation, chemical crosslinking, and electron microscopy experiments revealed that 14.7K exists in a stable high‐order oligomeric state (nonamer) in solution.
On the Generalization of Vladimirov and Wightman Generalized Functions
Authors: Trione Susana Elena
Published: July 2002

In this article we generalize to Rn the Vladimirov generalized functions and the Wightman‐type generalized functions. Our results are the formulae (I,1;1), (I,1;3), (I,1;4), (I,1;5), (I,2;1), (II,1;2), (II,1;3), (II,1;4), and (II,1;6). Here, we also introduce an n‐ dimensional multiplicative products of the Wightman‐type generalized functions (cf. formula (II,2;4)).
Fatty acid signalling in a mouse enteroendocrine cell line involves fatty acid aggregates rather than free fatty acids
Authors: Benson R. S. P. , Sidhu S. S. , Jones M. N. , Case R. M. , Thompson D. G.
Published: July 2002

Fatty acids induce cholecystokinin (CCK) secretion both in humans and from murine enteroendocrine cell lines. In both cases, only fatty acids above a critical acyl chain length (C10) are capable of inducing a response. Using the enteroendocrine cell line STC‐1, the aim of this study was to determine whether this acyl chain length dependency is related to the fact that longer chain fatty acids are relatively insoluble in aqueous solutions and, if so, whether it is insoluble aggregates of fatty acids rather than free fatty acids which evoke CCK secretion. Solutions of fatty acids (chain length C8–C14), which were judged by filtration and Zeta sizer measurement to contain no fatty acid aggregates, never evoked CCK secretion from STC‐1 cells. Filtering fatty acid solutions (of chain length C10, C12 and C14) through polytetrafluoroethylene (PTFE) filters (0.45 μm pore size) revealed a narrow concentration range for each acid over which the amount of fatty acid removed from the solution increased sharply due to the formation of fatty acid aggregates. Filtration experiments, in which suspensions of C10, C12 and C14 fatty acids were passed through pore sizes of 0.2, 0.45 or 1.2 μm, suggested that STC‐1 cells did not respond to fatty acid aggregates of greater than 1.2 μm, while at least 50 % of the CCK response was mediated by aggregates which were smaller than 0.45 μm. Fatty acids induce CCK secretion from STC‐1 cells by elevating intracellular Ca2+ concentration ([Ca2+]i). We therefore measured the effects on [Ca2+]i of filtered C10, C12 and C14 fatty acids. In all cases, [Ca2+]i responses were closely correlated with CCK secretion. Interestingly, while filtrates of fatty acid solutions evoked CCK secretion and elevated [Ca2+]i, freshly prepared solutions of fatty acids at the same concentration as the filtrates did not. This suggested that fatty acid aggregates were not in equilibrium with the solvent after filtration. The observation that the ability of C10, C12 and C14 filtrates to elevate [Ca2+]i decayed with time was consistent with this hypothesis. Furthermore, sonication of the filtrates abolished their ability to elevate [Ca2+]i. These data further suggest that it is a physical property of the fatty acid solution (the presence of insoluble fatty aggregates) which is responsible for the observed cellular responses. We conclude that Ca2+ mobilisation and CCK secretion in STC‐1 cells is driven by a signal transduction mechanism that senses insoluble fatty acid aggregates, rather than free fatty acids in solution.
Pulsating Flow in a 90 Degree Bifurcation
Authors: Schinas D. , Mathioulakis D. S.
Published: July 2002

The pulsating flow field in a 90 deg bifurcation was examined by performing LDV measurements in a model with square cross-sections and equal branch flow rates. The three-dimensional separation zones of both branches were studied revealing details of their temporal evolution. During acceleration the flow was attached, but close to the peak flow condition, separation initiated at both branches. The basic feature of the reverse flow zones at a given time instant was that these shrank streamwise in a direction perpendicular to the bifurcation plane and grew at the symmetry plane. Flow instabilities were strong in the horizontal branch during acceleration, in contrast to the vertical branch in which these appeared during deceleration. Comparison of this flow field for a particular time instant with the flow field under steady inlet conditions and similar Re, revealed that for the steady case the flow separated in the horizontal branch upstream of the unsteady case. [S0098-2202(00)03002-9]
Structural Damage Detection Using Linear Matrix Inequality Methods
Authors: Abdalla M. O. , Grigoriadis K. M. , Zimmerman D. C.
Published: July 2002

In this work, linear matrix inequality (LMI) methods are proposed for computationally efficient solution of damage detection problems in structures. The structural damage detection problem that is considered consists of estimating the existence, location, and extent of stiffness reduction in structures using experimental modal data. This problem is formulated as a convex optimization problem involving LMI constraints on the unknown structural stiffness parameters. LMI optimization problems have low computational complexity and can be solved efficiently using recently developed interior-point methods. Both a matrix update and a parameter update formulation of the damage detection is provided in terms of LMIs. The presence of noise in the experimental data is taken explicitly into account in these formulations. The proposed techniques are applied to detect damage in simulation examples and in a cantilevered beam test-bed using experimental data obtained from modal tests. [S0739-3717(00)00104-5]
Characteristics of a Liquid-Crystal Type ER-Fluid Variable Damper for Semiactive Vibration Suppression
Authors: Oh Hyun-Ung , Onoda Junjiro , Minesugi Kenji
Published: July 2002

A liquid-crystal type ER-fluid variable damper was fabricated to semiactively suppress the vibration of space truss structure. The principal characteristics of a liquid-crystal variable damper were measured in quasi-static tests, and a simple mathematical model of the damper was proposed. Semiactive control laws were derived from this model and the LQR theory. Numerical simulations were performed to compare the effectiveness of the semiactive vibration suppression using liquid-crystal type and particle-dispersion type ER-fluid variable dampers. The results indicated that the proposed control laws resulted in much better damping performances than is obtained with an optimally tuned passive system. In some cases such as large amplitude vibration, a variable damper using liquid-crystal type ER-fluid showed higher performance than one using particle-dispersion type ER-fluid. The results of semiactive vibration suppression experiments with a ten-bay truss beam also demonstrated that the liquid-crystal variable damper effectively suppresses vibration. [S0739-3717(00)00304-4]
Influence of the Exhaust System Design on Scavenging Characteristic and Emissions of a Four-Cylinder Supercharged Engine
Authors: Trenc Ferdinand , Bizjan Francˇisˇek , Sˇirok Brane , Hribernik Alesˇ
Published: July 2002

A four-stroke four-cylinder turbocharged engine can be fitted with two different types exhaust system: a simple common manifold fed by all cylinders, or a twin-branch manifold, where two selected cylinders, directed by the firing order, feed two separate turbine entries. In this case good utilization of the exhaust pressure pulse energy can be achieved at higher loads and lower engine speeds, leading to good overall turbocharger efficiency and favorable pressure distribution during the gas-exchange period. Improved engine scavenging capability affects quality and quantity of the fresh charge and consequently influences the exhaust gas emissions. If, in addition, valve overlap period is increased the benefit of this system is still more evident. Common manifold exhaust system shows its advantage through lower pumping losses at higher engine speeds and lower loads. Both systems were optimized and the results of numerical and experimental work are presented in the paper. [S0742-4795(00)00404-X]
Local Heat/Mass Transfer Measurements in a Rectangular Duct With Discrete Ribs
Authors: Cho H. H. , Wu S. J. , Kwon H. J.
Published: July 2002

The influence of arrangement and length of discrete ribs on heat/mass transfer and friction loss is investigated. Mass transfer experiments are conducted to obtain the detailed local heat/mass transfer information on the ribbed wall. The aspect ratio (width/height) of the duct is 2.04 and the rib height is one tenth of the duct height, such that the ratio of the rib height to hydraulic diameter is 0.0743. The ratio of rib-to-rib distance to rib height is 10. The discrete ribs were made by dividing each continuous rib into two, three, or five pieces, which were attached periodically to the top and bottom walls of the duct with a parallel orientation. The combined effects of rib angle and length of the discrete ribs on heat/mass transfer are considered for the rib angles (α) of 90 and 45 deg. As the number of the discrete ribs increases, the uniformity of the heat/mass transfer distributions increases. For α=90 deg, the heat/mass transfer enhancement with the discrete ribs is remarkable, while the heat/mass transfer performances are slightly higher than that of the transverse continuous ribs due to the accompanied high friction loss penalty. For α=45 deg, the average heat/mass transfer coefficients and the heat/mass transfer performances decrease slightly with the discrete ribs compared to the case of the angled continuous ribs.[S0889-504X(00)00103-3]
Stiffening Effects of High-Frequency Excitation: Experiments for an Axially Loaded Beam
Authors: Jensen J. S. , Tcherniak D. M. , Thomsen J. J.
Published: July 2002

According to theoretical predictions one can change the effective stiffness or natural frequency of an elastic structure by employing harmonic excitation of very high frequency. Here we examine this effect for a hinged-hinged beam subjected to longitudinal harmonic excitation. A simple analytical expression is presented, that relates the effective natural frequencies of the beam to the intensity of harmonic excitation. Experiments performed with a laboratory beam confirm the general tendency of this prediction, though there are discrepancies that cannot be explained in the framework of the linear Galerkin-discretized beam model. [S0021-8936(00)01302-7]
On Displacement Fields in Orthotropic Laminates Containing an Elliptical Hole
Authors: Chern S. M. , Tuttle M. E.
Published: July 2002

The classical Savin solution for the stress induced in an orthotropic plate containing an elliptical hole places no restrictions on remote rigid-body rotations. In this paper the Savin procedure is used to obtain a solution for which remote rigid-body rotations are required to be zero. The validity of these new results is demonstrated by comparing predicted displacement fields near a circular hole in specially orthotropic composite panels with those measured using moire´ techniques as well as those predicted using the finite element method. [S0021-8936(00)01303-9]
Two-Phase Flow Pressure Drop in Right Angle Bends
Authors: Graf Edward , Neti Sudhakar
Published: July 2002

Gas-liquid two-phase bubbly flows in right angle bends have been studied. Numerical predictions of the flow in right angle bends are made from first principles using an Eulerian-Eulerian two-fluid model. The flow geometry includes a sufficiently long inlet duct section to assure fully developed flow conditions into the bend. The strong flow stratification encountered in these flows warrant the use of Eulerian-Eulerian description of the flow, and may have implications for flow boiling in U-bends. The computational model includes the finer details associated with turbulence behavior and a robust void fraction algorithm necessary for the prediction of such a flow. The flow in the bend is strongly affected by the centrifugal forces, and results in large void fractions at the inner part of the bend. Numerical predictions of pressure drop for the flow with different bend radii and duct aspect ratios are presented, and are in general agreement with data in the literature. Measurements of pressure drop for an air-water bubbly flow in a bend with a nondimensional bend radius of 5.5 have also been performed, and these pressure drop measurements also substantiate the computations described above. In addition to the global pressure drop for the bend, the pressure variations across the cross section of the duct that give rise to the fluid migration (due to centrifugal forces), and stratification of the phases are interesting in their own right. [S0098-2202(00)01004-X]
Plane Turbulent Surface Jets in Shallow Tailwater
Authors: Ead S. A. , Rajaratnam N.
Published: July 2002

This paper presents a theoretical and laboratory study of plane turbulent surface jets in shallow tailwater. The main objective was to show that when the depth of tailwater is finite, the momentum flux in the forward flow in the surface jet decays appreciably with the distance from the nozzle producing the surface jet. This decay is shown to be due to the entrainment of the return flow which has negative momentum and an increase in the tailwater depth further away from the nozzle produces this return flow. An extensive set of experiments, with different Froude numbers and offset ratios, was conducted to observe and quantify the growth of the surface jet, the decay of the velocity scale, and the momentum flux and the variation of the volume flux. On the whole, the results from this study highlight the effect of the tailwater depth on the behavior of plane turbulent surface jets when the ambient fluid has a limited extent.
Study on Creep-Fatigue Damage Evaluation for Boiler Weldment Parts
Authors: Ogata Takashi , Yaguchi Masatsugu
Published: July 2002

Creep-fatigue tests on the heat-affected zone(HAZ) simulated materials, base metal, weld metal and weld joint of 2.25Cr-1Mo steel, and elastic-plastic and creep FEM analysis for the weld joint were conducted. It was found from the comparison between experimental evidences and the analytical results that “Type IV” cracking was caused by two major reasons. One is accumulation of creep strain during strain hold in the fine-grain region is larger than that in other regions, suggesting progress of creep damage in the fine-grain region prior to other regions. The other is existence of triaxial tensile stress field within the fine-grain region caused reduction of failure ductility. Crack initiation portion and failure life under the creep-fatigue test could be well predicted by the nonlinear damage accumulation model based on the FEM analysis results.
Flow in Porous Media of Variable Permeability and Novel Effects
Authors: Siginer D. A. , Bakhtiyarov S. I.
Published: July 2002

The flow of polymeric liquids in a porous medium of variable permeability represented by a cylindrical tube randomly packed with glass spheres is studied. The cylinder represents two porous media of different permeabilities and same porosity arranged in series. We show that the energy loss is higher if the polymeric solution flows first through the porous medium with the smaller permeability rather than through the section of the cylinder with the larger permeability. The difference in energy requirements increases with increasing Reynolds number and may be as high as 25–35 percent for Reynolds numbers of O(1). This is a novel effect not observed for Newtonian and highly shear thinning inelastic fluids flowing through the same configuration. Energy requirements for the same volume flow rate are much higher than a Newtonian fluid of the same zero shear viscosity as the polymeric solution. Energy loss increases with increasing Reynolds number at a fixed concentration to level off at a Reynolds number of O(1). At a fixed Reynolds number, the loss is a strong function of the concentration and shows large increases with increasing concentration. For shear-thinning oil field spacer fluids De∼0.1 represents a good criterion for the onset of elasticity effects. For solutions of polyacrylamide De∼0.1 corresponds approximately to the flow rate at which pressure drop starts becoming dependent on the flow direction. Expressions for the friction factor and the resistance coefficient as a function of the Reynolds number have been developed using the inelastic KPK (Kutateladze-Popov-Kapakhpasheva) and viscoelastic eight constant Oldroyd models, respectively. The behavior of inelastic shear-thinning and viscoelastic fluids as represented by oil field spacer fluids and aqueous solutions of polyacrylamide is predicted qualitatively except the difference in energy requirements when the flow direction is reversed in the case of the latter.
Pulsed Gas Feeding for Stoichiometric Operation of a Gas-Solid Vortex Flow Solar Chemical Reactor
Authors: Kra¨upl Stefan , Steinfeld Aldo
Published: July 2002

The thermodynamic implications of conducting the solar combined ZnO-reduction and CH4-reforming under stoichiometric and non-stoichiometric conditions are examined. For a solar flux concentration ratio of 5000 and for a solar cavity-receiver operating at 1300 K, the solar thermal conversion efficiency is 55 percent for a stoichiometric molar ratio of ZnO and CH4, and decreases by 50 percent when using excess methane by a factor 10 over the stoichiometric molar amount. A technical solution for operating a gas-solid vortex-flow solar reactor under stoichiometric conditions was established by using a pulsed-feed of methane to carry out the particles of ZnO. Using this technique, nearly stoichiometric operation was demonstrated with a prototype reactor in a high-flux solar furnace, thereby opening up a means for efficient conversion of sunlight into chemical fuels.
Measure to Reduce the Bounce of a Movable Part in an Electromagnetic Contactor
Authors: Muramatsu N. , Tsutsumi K.
Published: July 2002

This study considered the measure for bouncing produced on the movable part of an electromagnetic contactor during return. For this purpose, the way of thinking of a dynamic vibration absorber was applied to the collision problem. The results obtained are as follows. (1) The crossbar bounces approximately 3 mm after colliding twice against the housing. (2) Inserting pieces of urethane rubber (AC-6ME material) between the movable core and the crossbar under some conditions reduced the bounce to about one third. (3) This is due to a remarkable hysteresis characteristic of AC-6ME material seen under its compressive deformation.
Field Demonstration of a 1.5 MW Industrial Gas Turbine With a Low Emissions Catalytic Combustion System
Authors: Yee D. Y. , Lundberg K. , Weakley C. K.
Published: July 2002

An electric utility grid connected test facility has been established at Silicon Valley Power (SVP) in Santa Clara, California to validate the reliability, availability, maintainability, and durability (RAMD) of a commercial-ready catalytic combustor system (XONON). Installed in the Silicon Valley Test Facility (SVTF) is a 1.5MW Kawasaki MIA-13A gas turbine fitted with a catalytic combustor. The gas turbine package is controlled by a Woodward MicroNet control system. The combustor utilizes a two stage lean premix preburner system to obtain the required catalyst inlet temperatures and low NOx over the operating load range. The fuel-air mixer incorporates counter rotating swirlers to mix the catalyst fuel and air to achieve the desired uniformity. The patented catalyst design is composed of specially coated metal foils. Overall engine performance was measured and the emissions were continuously monitored. As of Dec. 1999, emissions of NOx<2.5 ppmv and CO and UHC<6 ppmv have been maintained at 100 percent load for over 3700 hours of operation on the utility grid. The turbine continues to operated 24 hours a day, 7 days per week with commercial levels of unit availability.
Determination of Thermoacoustic Response in a Demonstrator Gas Turbine Engine
Authors: Arana C. A. , Sekar B. , Mawid M. A. , Graves C. B.
Published: July 2002

This paper describes an analytical and experimental investigation to obtain the thermoacoustic response of a demonstrator gas turbine engine combustor. The combustor acoustic response for two different fuel injector design configurations was measured. It was found that the combustor maximum peak to peak pressure fluctuations were 0.6 psi to 2 psi for configuration A and B, respectively. Based on the measured acoustic response, another experimental investigation was conducted to identify the design features in configuration B that caused the increase in the acoustic response. The data showed that by changing the fuel injector swirler’s vane to inner passage discharge area ratio, the engine acoustic response could be lowered to an acceptable level. A simplified analytical model based on the lumped-parameter approach was then developed to investigate the effect of geometrical changes upon the engine response. The analytical model predicted the fuel injector/swirlers acoustic response as a function of the swirlers inner passage discharge area ratio and frequency. The predictions were consistent with the experimental observations, in particular, it was predicted that as the area ratio was increased, the system reactance was decreased and as a result the system changed from a damping to an amplifying system.
Implementation and Validation of a New Soot Model and Application to Aeroengine Combustors
Authors: Balthasar M. , Mauss F. , Pfitzner M. , Mack A.
Published: July 2002

The modeling of soot formation and oxidation under industrially relevant conditions has made significant progress in recent years. Simplified models introducing a small number of transport equations into a CFD code have been used with some success in research configurations simulating a reciprocating diesel engine. Soot formation and oxidation in the turbulent flow is calculated on the basis of a laminar flamelet library model. The gas phase reactions are modeled with a detailed mechanism for the combustion of heptane containing 89 species and 855 reactions developed by Frenklach and Warnatz and revised by Mauss. The soot model is divided into gas phase reactions, the growth of polycyclic aromatic hydrocarbons (PAH) and the processes of particle inception, heterogeneous surface growth, oxidation, and condensation. The first two are modeled within the laminar flamelet chemistry, while the soot model deals with the soot particle processes. The time scales of soot formation are assumed to be much larger than the turbulent time scales. Therefore rates of soot formation are tabulated in the flamelet libraries rather than the soot volume fraction itself. The different rates of soot formation, e.g., particle inception, surface growth, fragmentation, and oxidation, computed on the basis of a detailed soot model, are calculated in the mixture fraction/scalar dissipation rate space and further simplified by fitting them to simple analytical functions. A transport equation for the mean soot mass fraction is solved in the CFD code. The mean rate in this transport equation is closed with the help of presumed probability density functions for the mixture fraction and the scalar dissipation rate. Heat loss due to radiation can be taken into account by including a heat loss parameter in the flamelet calculations describing the change of enthalpy due to radiation, but was not used for the results reported here. The soot model was integrated into an existing commercial CFD code as a post-processing module to existing combustion CFD flow fields and is very robust with high convergence rates. The model is validated with laboratory flame data and using a realistic three-dimensional BMW Rolls-Royce combustor configuration, where test data at high pressure are available. Good agreement between experiment and simulation is achieved for laboratory flames, whereas soot is overpredicted for the aeroengine combustor configuration by 1–2 orders of magnitude.
Combined Heat and Mass Transfer Under Different Inlet Subcooling Modes During NH3-H2O Falling Film Absorption Process
Authors: Kang Y. T. , Fujita Y. , Kashiwagi T.
Published: July 2002

Experiments were conducted for ammonia-water falling film absorption in a plate heat exchanger with offset strip fins. The objectives of this paper were to analyze combined heat and mass transfer during the ammonia-water absorption process under different inlet subcooling modes, and to obtain heat transfer coefficients (Nusselt number). This paper examined the effects of the inlet subcooling modes, the inlet concentration difference, liquid Reynolds number, and vapor Reynolds number on the heat transfer performance. Inlet liquid concentrations were set at 0, 5, 10, and 15 percent in mass of ammonia, while inlet vapor concentration ranged from 64.7 to 83.6 percent. Experiments were conducted in three ways according to the inlet subcooling conditions, i.e., Case A Tv>Tl, Case B Tv∼Tl, and Case C Tv<Tl. In Case A, there was a rectification process at the top of the test section by the inlet subcooling effect. Water desorption was confirmed in the experiments, which resulted in a lower absorption performance. The heat transfer coefficient increased as the inlet subcooling increased in all cases. The effect of inlet subcooling on heat transfer performance was more significant in Case A than in Cases B and C. The inlet subcooling had more significant effect on the heat transfer performance than the inlet concentration difference. Nusselt number increased as liquid and vapor Reynolds numbers increased. The vapor velocity should be maximized to increase absorption performance in cocurrent ammonia-water absorption process. The parametric analysis provides fundamental understandings of the ammonia-water absorption process, and thus gives a guideline for heat exchanger compactness in ammonia-water absorption systems.
Two-Dimensional Study of the Turbulent Wake Behind a Square Cylinder Subject to Uniform Shear
Authors: Saha A. K. , Biswas G. , Muralidhar K.
Published: July 2002

The flow past a square cylinder at a Reynolds number of 20,000 has been simulated through direct calculations and through the calculations using turbulence model. The present investigation highlights significant differences between the two approaches in terms of time-averaged flow, Strouhal number, and aerodynamic forces. The time-averaged drag coefficient and the rms fluctuations due to the direct calculations are higher than those due to the turbulence model. However, Strouhal number is underpredicted in the direct calculations. The effect of shear on the flow has also been determined using the turbulence model. The time-averaged drag coefficient is found to decrease with the increase in shear parameter up to a certain value. Then it increases with the further increase in the shear parameter. On the other hand, lift coefficient increases with the increase in shear parameter. Strouhal number shows a decreasing trend with the increase in shear parameter whereas the rms values of drag and lift coefficients increase with the shear parameter. The Ka´rma´n vortex street, mainly comprising clockwise vortices due to shear, decays slowly compared to the uniform flow condition.