bluuebunny/crossref_metadata_2025 huggingface dataset:
Local atomic and electronic structure of Al90Fe
xCe10-x
alloys: XAFS analysis
Authors: Mansour A. N. , Cibin G. , Marcelli A. , Sevastyanova T. , Yalovega G. , Soldatov A. V.
Published: July 2002

X-ray absorption fine structure (XAFS) above the Fe K-edge and the Ce L3-edge in amorphous Al90FexCe10-x (x = 3, 5, and 7) alloys have been measured and analyzed. Quantitative analyses of the Fe K-edge and Ce L3-edge EXAFS spectra are limited to local structure parameters of the first coordination sphere. Using a theoretical multiple scattering (MS) approach, we show that the Fe and Ce XANES are sensitive to the structure of coordination spheres, which extend up to nearly 4.5 Å. Comparison of experimental XANES spectra with theoretical MS results allows one to determine the local structure around the iron and cerium sites up to at least the third shell of atoms.
Diffraction anomalous fine structure of forbidden Bragg reflections: charge localization and structure of the octahedral site in magnetite
Authors: Renevier H. , Joly Y. , García J. , Subías G. , Proietti M. G. , Hodeau J. L. , Blasco J.
Published: July 2002

Resonant X ray scattering has been used to investigate charge localization on the octahedral iron atoms in magnetite below and above the Verwey temperature. We have measured the DAFS spectra of the 002 and 006 `forbidden' Bragg reflections permitted by the anisotropy of the iron anomalous scattering factor. We performed ab initio calculations which are in fair agreement with the experiment in the near edge region and demonstrate the sensitivity of the DAFS spectra to tiny structural and electronic changes. No change is observed, in the energy and azimuthal dependences, when the sample is cooled down below the Verwey temperature. Charge ordering can be definitely excluded and different charge localization schemes discarded. Ab initio simulations, performed by using the refined crystallographic structure proposed for the room temperature phase, do not show a good agreement with the experiment in the extended region of the DAFS spectrum. This point is being investigated.
Electroslag and submerged arc stainless steel strip cladding
Authors: Pak Susan , Rigdal Solveig , Karlsson Leif , Gustavsson Ann‐Charlotte
Published: July 2002

Stainless steel strip cladding is a flexible and economical way of depositing a corrosion resistant, protective layer on a load‐bearing mild or low alloy steel. Strip cladding is therefore widely used in the production of components for the chemical, petrochemical and nuclear industries, for example.
Barriers to career development within the LIS profession
Authors: Dalton Peter , Mynott Glen , Shoolbred Michael
Published: July 2002

The paper, based on the findings of the Library and Information Commission (LIC) report on Cross‐sectoral Mobility in the LIS Profession, considers some of the barriers to career development within the Library and Information Services profession. It focuses specifically upon difficulties experienced by LIS professionals in moving to different sectors of the profession. It discusses issues such as professional segregation; employer prejudice; poor employment strategies; lack of confidence among LIS professionals; training; and lack of professional support. In addition to outlining some of the barriers to the career development of LIS professionals, the paper offers a number of recommendations for employers, professional bodies and LIS professionals that may help to alleviate many of these barriers.
Using the Internet as a teaching resource
Authors: Jefferies Pat , Hussain Fiaz
Published: July 2002

Increasingly the Internet is being used by students to gather a variety of data and gain an extensive range of experience as part of their learning activity. The paper discusses how the Internet may be used to support learning and teaching and some of the motivation underpinning its adoption. It refers to use of the Internet in a final year module on multimedia run by the Department of Computer and Information Sciences at De Montfort University, one of the main purposes being to promote collaborative student project work. The authors present an analysis of feedback that has been gained from students’ experiences of using network technology. The article concludes by outlining some of the issues raised by using the Internet as a learning and teaching resource.
Empowerment through involvement: a case study of TGI Fridays restaurants
Authors: Lashley Conrad
Published: July 2002

Suggestions for improvements in service quality in hospitality operations frequently advocate the use of empowerment as a strategy for the management of employees. Analysis of employer initiatives that claim to empower employees needs to distinguish those initiatives labelled empowerment and those which are empowering. At root, empowerment should develop a sense of personal efficacy in employees. TGI Fridays is an organization that makes a service offer to customers that can be described as “mass customisation”. The successful service encounter requires employees to provide customers with both advice and counselling in the way they construct their meal experience, and a personalised service performance. To make this happen, employees are managed through a cluster of approaches which are defined as “empowerment through involvement”. That is, they include some development of personal efficacy and engagement in service performance, but which involves limited decision making apart from that required of their role in service performance.
A three‐perspective approach to understanding culture in retail organizations
Authors: Harris Lloyd C. , Ogbonna Emmanuel
Published: July 2002

This article demonstrates the usefulness of applying the multiperspective framework developed by Martin (1992) to the analyses of organizational culture. The paper presents empirical evidence derived from the UK retail sector to illustrate that the culture of retail organizations can be more clearly understood by reference to Martin’s (1992) three perspectives. Moreover, it argues that the organizational members’ perceptions of culture correspond with their respective hierarchical positions. The paper concludes with an exploration of theoretical and practical implications derived from the application of Martin’s (1992) three‐perspective framework.
An empirical assessment of institutional and individual research productivity in international operations management
Authors: Babbar Sunil , Prasad Sameer , Tata Jasmine
Published: July 2002

Assesses institutional and individual research productivity in the area of international operations management (IOM) by reviewing publications in 21 leading operations management (OM) journals over the 12‐year period from 1986 through 1997. Also assesses the IOM research output of the journals and the relative contributions of academicians and practitioners to IOM research appearing in these journals. Among the journals examined for the 12‐year period of this study, based on annual output and quality of published IOM research, Production and Operations Management, International Journal of Operations & Production Management, and European Journal of Operational Research served as the leading outlets for IOM research. The 21 journals published a total of 550 IOM articles over the 12‐year period with academicians authoring approximately 86 percent and practitioners 14 percent of this IOM research. The study provides insights on the IOM research productivity and quality of institutions and individuals and offers suggestions for furthering the cause of IOM research.
The impact of 360‐degree feedback on planning for career development
Authors: Brutus Stéphane , London Manuel , Martineau Jennifer
Published: July 2002

This study focused on the relationship between 360‐degree (multi‐source) survey feedback to managers and subsequent selection of development goals. We hypothesized that performance ratings would be negatively related to setting development goals, that supervisor ratings would have a greater effect than ratings from peers or subordinates in the selection of developmental goals, and that self‐other discrepancies would be related to goal selection. Data from 2,163 managers showed that multi‐source feedback contributed to the selection of developmental goals. However, contrary to expectations, subordinate ratings were most important to goal setting compared to ratings from any other sources. Direct feedback itself affected goal selection, not its relationship to self‐perceptions. For several goals, the relationship between performance ratings and goal selection was stronger for lower level managers. Implications of the results for the practice of 360‐degree feedback and related research are discussed.
A combined finite/discrete element simulation of shot peening processes – Part I: studies on 2D interaction laws
Authors: Han K. , Peric D. , Crook A.J.L. , Owen D.R.J.
Published: July 2002

In the first part of this series of papers on the combined finite/discrete element simulation of shot peening processes, different contact interaction laws for 2D cases are extensively studied with special attention given to the proper selection of the parameter values involved, which is one of the key issues for successful direct simulation. In addition, computational issues including contact forces, partial contact, energy dissipation, and rheological representation are addressed. Numerical examples for a single shot impact system simulated by the coupled finite/discrete element method using different interaction laws are provided to verify the proposed approaches. The results are also compared with those obtained by using only finite element methods. Findings obtained by performing 2D simulations will, in the subsequent article, be used in realistic computational simulations of 3D shot peening processes.
Developing Competent Managers
Authors: Kilcourse Tom
Published: July 2002

Questions the value of the current emphasis on NVQs and MBAs in
developing managers for a turbulent future. Aimed at colleagues in the
management development field, argues that their role is strategic and
that the separation of MD and OD is harmful. Competences are specific to
organizational culture, and the individual needs to develop in parallel
with the organization. Suggests that those should not be considered as
separate processes. Also points out that the more general competences
are, the less useful they become within the organization.
Zinc phosphate as corrosion inhibitive pigment of waterborne epoxy paints used for steel protection
Authors: Caprari J.J. , Di Sarli A.R. , del Amo B.
Published: July 2002

Health and safety legislation has forced changes in the type of anticorrosive pigments used in paint formulations, mainly focused on their substitution with different phosphates. The zinc phosphate pigment used with different types of binders has provided contradictory experimental results. In this paper, waterborne anticorrosive paints pigmented with zinc phosphates were studied. The main variables considered were PVC and the anticorrosive pigment content. Accelerated tests (salt spray, humidity chamber, and electrochemical tests) were performed to evaluate the paints’ anticorrosive performance. Good correlation was found using salt spray and impedance tests. From analysis of the time dependence of all the experimental results it was concluded that an efficient steel protection could be obtained using a waterborne epoxy primer pigmented with zinc phosphate. Such protection is attained through the barrier effect afforded by the paint film as well as the precipitation of a pretty stable ferric phosphate layer under the intact and damaged coating areas.
Development of a Commercial Made‐to‐Measure Garment Pattern System
Authors: Turner J.P.
Published: July 2002

Describes a PC‐based CAD system for producing made‐to‐measure garment patterns which has been developed and implemented in the commercial environment of a bridalwear manufacturer. The software simulates the hand drafting methods of the company while automating pattern production with the following benefits: first, very rapid production of made‐to measure patterns; second, production of patterns which require minimal alteration at first fitting; third, a user friendly interface with very short training period; fourth, the de‐skilling of the pattern cutting procedure so that problems of staff turnover and training are minimal; and fifth, the elimination of human error in pattern cutting. Initial software development concentrated on bodice patterns. Further enhancements included sleeves and skirts and the mixing and matching of these three components of a dress. Cutting layouts were produced using automatic layout algorithms so that the whole procedure from order and measurements entry through pattern drafting and lay‐planning to the final full scale plotting could be carried out automatically. Furthermore, a queuing system allowed several orders previously entered on the computer to be processed in succession without any intervention by an operator. All the company’s styles are now held by the computer, which is in constant use, to the exclusion of the previously used skilled and lengthy hand drafting methods.
Skill flexibility among schoolteachers: operationalization and organizational implications
Authors: Rosenblatt Zehava , Inbal Batia
Published: July 2002

This study is an empirical investigation into the effect of skill flexibility on work attitudes and performance and into managerial attitudes toward skill flexibility. Secondary schools in Israel were used as a case in point, and skill flexibility of teachers was operationalized, distinguishing between role flexibility (the combination of teaching and other school roles) and functional flexibility (the combination of several teaching areas). It was found that both role and functional flexibility were associated with improved teachers’ work performance. Role flexibility was also linked to high organizational commitment and low powerlessness. The findings of the study are supported by interviews with principals, who were generally appreciative of skill‐flexible teachers, but raised practical difficulties related to organizational support of skill flexibility.
Numerical aerodynamic analysis of large buildings using a finite element model with application to a telescope building
Authors: Codina Ramon , Morton Christopher , Oñate Eugenio , Soto Orlando
Published: July 2002

Presents a numerical strategy for the aerodynamic analysis of large buildings, with an application to the simulation of the air flow within a telescope building. The finite element formulation is presented first, and then the methodology followed to obtain significant data from the calculations is described. The quality of the ventilation of the building is defined by the average residence times, and the feasibility of this ventilation by the actions created on the instruments and the general flow pattern.
Towards a formal theory of development/evolution and characterization of time discretized operators for heat transfer
Authors: Tamma Kumar K. , Zhou Xiangmin , Sha Desong
Published: July 2002

The time‐discretization process of transient equation systems is an important concern in computational heat transfer applications. As such, the present paper describes a formal basis towards providing the theoretical concepts, evolution and development, and characterization of a wide class of time discretized operators for transient heat transfer computations. Therein, emanating from a common family tree and explained via a generalized time weighted philosophy, the paper addresses the development and evolution of time integral operators [IO], and leading to integration operators [InO] in time encompassing single‐step integration operators [SSInO], multi‐step integration operators [MSInO], and a class of finite element in time integration operators [FETInO] including the relationships and the resulting consequences. Also depicted are those termed as discrete numerically assigned [DNA] algorithmic markers essentially comprising of both: the weighted time fields, and the corresponding conditions imposed upon the dependent variable approximation, to uniquely characterize a wide class of transient algorithms. Thereby, providing a plausible standardized formal ideology when referring to and/or relating time discretized operators applicable to transient heat transfer computations.
Managing technology risks in the healthcare sector: disaster recovery and business continuity planning
Authors: Iyer Raja K. , Bandyopadhyay Kakoli
Published: July 2002

The relentless onslaught of computers and communications technologies has recently descended on the healthcare industry. Fortunately, however, the utilization of technologies in healthcare delivery and administration could not be timelier because of the need to control escalating health costs. While the proliferation of information and communication technologies in healthcare, referred to as health management information systems (HMIS), is certainly long overdue in healthcare organizations (HCOs), it is important to recognize and be prepared for the vulnerabilities of these technologies to natural, technological, and man‐made disasters. This paper describes how HCOs have justifiably become dependent on HMIS and how these organizations may proactively plan for disasters which can impact on HMIS. A phased approach, referred to as the disaster recovery and business continuity (DRBC) planning model, is presented in the paper as an approach to develop and implement business continuity plans in HCOs.
Managing electronic reserves
Authors: Dugdale Christine
Published: July 2002

Digital services can solve some problems facing print‐based academic libraries. They also provide opportunities for librarians to become proactive by adopting pivotal roles in shaping their institutions’ teaching and learning strategies. Digital collections take information outside libraries’ physical confines. As managers of digital information systems, librarians cannot remain mere intermediaries, though some find that digital collections present unwanted learning challenges and threats to current working practices. Librarians must develop new roles and working practices and initiate the cultural changes that will alter others’ perceptions of them. An electronic collection can underpin current pedagogic styles, initiate new teaching and learning practices and support lifelong learning skills through the close collaboration and interchange of professional academic and librarian roles. The potentiality of such collaboration is currently being explored through the expansion of the ResIDe Electronic Library at the University of the West of England, Bristol.
Enhancement‐led Higher Education?
Authors: Yorke Mantz
Published: July 2002

Starts from the premiss that the Government White Paper of 1991 and the
Further and Higher Education Act of 1992, in concentrating their
attention on accountability, paid insufficient attention to enhancing
the quality of provision in higher education. Suggests that whilst the
present arrangements for the external scrutiny of quality in higher
education (quality audit and quality assessment) have led to some
improvements, the future demands on the sector – well articulated in the
MacFarlane report of 1993 – are likely to require a much more proactive
approach to the enhancement of quality. Proposes that a funding agenda,
explicitly oriented towards enhancement, could act as an inducement to
the sector to respond in strategic ways to the challenges posed in the
MacFarlane Report. A consequence of the approach would be the
establishment of revised arrangements for external quality scrutiny at
national level.
Research universities versus teaching universities ‐ public perceptions and preferences
Authors: Fram Eugene H. , Lau Gloria H.
Published: July 2002

Claims post‐secondary institutions are facing two major problems ‐ enrolment declines and increases in operating costs. Suggests that, as the turmoil in higher education has accelerated, the research university seems to have lost public support, while the teaching university has been placed in a more favourable light. Reports on a pilot study of the public’s preferences for, and perceptions of, the research‐oriented and teaching‐oriented universities. Asks whether one or the other is more favoured by the US public. Presents the perceptions and preferences from 100 personal interviews, utilizing a psychological projective technique to gather the information.
Information technology, globalization and Africa’s information development
Authors: Jimba Samuel W.
Published: July 2002

The world is witnessing the commencement of a new revolution ‐ the information revolution. Like all other revolutions before it, the information revolution will have cataclysmic effects on human history. Already the revolution has transformed the world into a global village where information is produced, transmitted and exchanged from remote locations in a matter of seconds. Business applications of the Internet are also improving the economies of various countries. However, for Africa, the information environment is still underdeveloped and is thus creating impediments to the participation of the continent in the information revolution. This paper discusses this environment and offers suggestions for Africa’s participation in the world’s fourth revolution.
Knowledge work and telework: an exploratory study
Authors: Bentley Kaye , Yoong Pak
Published: July 2002

Describes a case research study into how knowledge workers adopt telework as an alternative work arrangement. It reports how knowledge workers in two New Zealand organisations organise their workload to take advantage of the information and Internet technology available to them in their work and home environments. The findings of the study indicate that knowledge workers are inclined to use home‐based teleworking as an adjunct to the work done during normal business hours. Their preference is still to work at the office for most of their work time. Discusses the implications of the findings for practice and research.
Direct rapid tooling: a review of current research
Authors: Karapatis N.P. , van Griethuysen J.P.S. , Glardon R.
Published: July 2002

Rapid prototyping technologies are now evolving toward rapid tooling. The reasons for this extension are found in the need to further reduce the time‐to‐market by shortening not only the development phase, but also the industrialization phase of the manufacturing process. The present state of rapid tooling is reviewed and the direct rapid tooling concept, aimed at developing direct and rapid tool manufacturing processes, is presented, along with three promising methods. Their intrinsic properties are outlined and compared. Necessary research and development are described in terms of direct rapid tooling requirements.
Structural basis of pheromone binding to mouse major urinary protein (MUP‐I)
Authors: Timm David E. , Baker L.J. , Mueller Heather , Zidek Lukas , Novotny Milos V.
Published: July 2002

The mouse major urinary proteins are pheromone‐binding proteins that function as carriers of volatile effectors of mouse physiology and behavior. Crystal structures of recombinant mouse major urinary protein‐I (MUP‐I) complexed with the synthetic pheromones, 2‐sec‐butyl‐4,5‐dihydrothiazole and 6‐hydroxy‐6‐methyl‐3‐heptanone, have been determined at high resolution. The purification of MUP‐I from mouse liver and a high‐resolution structure of the natural isolate are also reported. These results show the binding of 6‐hydroxy‐6‐methyl‐3‐heptanone to MUP‐I, unambiguously define ligand orientations for two pheromones within the MUP‐I binding site, and suggest how different chemical classes of pheromones can be accommodated within the MUP‐I β‐barrel.
Modulation of K+ currents in Xenopus spinal neurons by p2y receptors: a role for ATP and ADP in motor pattern generation
Authors: Brown Paul , Dale Nicholas
Published: July 2002

We have investigated the pharmacological properties and targets of p2y purinoceptors in Xenopus embryo spinal neurons. ATP reversibly inhibited the voltage‐gated K+ currents by 10 ± 3 %. UTP and the analogues α,β‐methylene‐ATP and 2‐methylthio‐ATP also inhibited K+ currents. This agonist profile is similar to that reported for a p2y receptor cloned from Xenopus embryos. Voltage‐gated K+ currents could be inhibited by ADP (9 ± 0.8 %) suggesting that a further p2y1‐like receptor is also present in the embryo spinal cord. Unexpectedly we found that α,β‐methylene‐ADP, often used to block the ecto‐5′‐nucleotidase, also inhibited voltage‐gated K+ currents (7 ± 2.3 %). This inhibition was occluded by ADP, suggesting that α,β‐methylene‐ADP is an agonist at p2y1 receptors. We have directly studied the properties of the ecto‐5′‐nucleotidase in Xenopus embryo spinal cord. Although ADP inhibited this enzyme, α,β‐methylene‐ADP had no action. Caution therefore needs to be used when interpreting the actions of α,β‐methylene‐ADP as it has previously unreported agonist activity at P2 receptors. Xenopus spinal neurons possess fast and slow voltage‐gated K+ currents. By using catechol to selectively block the fast current, we completely occluded the actions of ATP and ADP. Furthermore, the purines appeared to block only the fast relaxation component of the tail currents. We therefore conclude that the p2y receptors target only the fast component of the delayed rectifier. As ATP breakdown to ADP is rapid and ADP may accumulate at higher levels than ATP, the contribution of ADP acting through p2y1‐like receptors may be an important additional mechanism for the control of spinal motor pattern generation.
Discussion: “Development of Advanced Compressor Airfoils for Heavy-Duty Gas Turbines—Part II: Experimental and Theoretical Analysis” [ASME J. Turbomach., 122, No. 3, pp. 406–414 (2000)]1
Authors: Cumpsty N. A.
Published: July 2002

[S0889-504X(00)02702-1]
Application of Fuzzy Set Theory in the Scheduling of a Tandem Cold-Rolling Mill
Authors: Dixit U. S. , Dixit P. M.
Published: July 2002

In a tandem cold-rolling mill, a strip is successively reduced in gauge at each stand as it passes through the mill. The optimal scheduling of a tandem mill is an important but difficult task. In this work, a scheduling problem is considered as an optimization problem which minimizes the total specific power and satisfies certain constraints. Since the material properties and friction coefficient are not known precisely, they are treated as fuzzy numbers. The fuzzy set theory is applied to find out an optimum drafting pattern. The methodology is illustrated by means of a few examples. It is observed that the schedule in which the maximum reduction is achieved in the first pass results in minimum specific power; however, its reliability is poor. Optimization using fuzzy set theory provides a solution which meets the twin requirements of high reliability and minimum power. [S1087-1357(00)00902-3]
Vibration Analysis of a Sensor-Integrated Ball Bearing
Authors: Holm-Hansen Brian T. , Gao Robert X.
Published: July 2002

This paper presents an analysis of the vibrational behavior of a deep groove ball bearing with a structurally integrated force sensor. The miniaturized force sensor, accommodated within a slot on the bearing’s outer ring, provides on-line condition monitoring capability to the bearing. Analytical and finite element models were developed to predict the sensor output due to bearing dynamic load and rotational speed variations. Experimental studies were conducted on a ball bearing to validate the analytical and numerical solutions. Good agreement was found between the model-predicted sensor outputs and the experimental results. The findings validated the approach of integrated-sensing for on-line bearing condition monitoring. [S0739-3717(00)00203-8]
On Eigenfrequencies of an Anisotropic Sphere
Authors: Chen, W. Q. , Cai, J. B. , Ye, and G. R. , Ding H. J.
Published: July 2002

This note presents exact frequency equations of two independent classes of vibrations of a spherically isotropic solid sphere with fixed boundary conditions. Numerical calculations are performed and comparison between two different materials is made. Some useful observations are obtained. [S0021-8936(00)00102-1]
Nonuniform Flow in a Compressor Due to Asymmetric Tip Clearance
Authors: Song Seung Jin , Cho Seung Ho
Published: July 2002

This paper presents an analytical study of flow redistribution in a compressor stage due to asymmetric tip clearance distribution. The entire stage is modeled as an actuator disk and it is assumed that upstream and downstream flow fields are determined by the local tip clearance. The flow is assumed to be inviscid and incompressible. First, an axisymmetric flow model is used to connect upstream and downstream flows. Second, a linear perturbation approximation is used for nonaxisymmetric analysis in which each flow variable is assumed to consist of a mean (axisymmetric value) plus a small perturbation (asymmetric value). Thus, the perturbations in velocity and pressure induced by the tip clearance asymmetry are predicted. Furthermore, rotordynamic effects of such flow nonuniformity are examined as well. [S0889-504X(00)01404-5]
An Energy-Based Model of Longitudinal Splitting in Unidirectional Fiber-Reinforced Composites
Authors: Oguni K. , Ravichandran G.
Published: July 2002

Unidirectional fiber-reinforced composites are often observed to fail in a longitudinal splitting mode in the fiber direction under far-field compressive loading with weak lateral confinement. An energy-based model is developed based on the principle of minimum potential energy and the evaluation of effective properties to obtain an analytical approximation to the critical stress for longitudinal splitting. The analytic estimate for the compressive strength is used to illustrate its dependence on material properties, surface energy, fiber volume fraction, fiber diameter, and lateral confining pressure. The predictions of the model show good agreement with available experimental data. [S0021-8936(00)02003-1]
Intrinsic Errors on Sheet Strain Measurements Based on a Printed Square Grid
Authors: Bruneel Herman C. J.
Published: July 2002

The paper studies the intrinsic errors on strain measurements induced by the application of an electrochemical etched square grid through serigraphy. Systematic periodic strains are observed when the etched grid is directly measured before any mechanical deformation. These apparent, non-zero strains are the errors induced by the imperfection of the applied grid. They determine the limiting precision of the measuring process. The errors are due to interference between the periodic square grid and an underlying periodic structure, the dot structure of the printer used for the original drawing of the grid or the periodic pitch of the serigraphic tissue and even both. Although they are small, they can suggest an unstable deformation, even at large strains. [S1087-1357(00)02004-9]
Analysis of Aerodynamically Induced Whirling Forces in Axial Flow Compressors
Authors: Spakovszky Z. S.
Published: July 2002

A new analytical model to predict the aerodynamic forces in axial flow compressors due to asymmetric tip-clearance is introduced. The model captures the effects of tip-clearance induced distortion (i.e., forced shaft whirl), unsteady momentum-induced tangential blade forces, and pressure-induced forces on the spool. Pressure forces are shown to lag the tip-clearance asymmetry, resulting in a tangential (i.e., whirl-inducing) force due to spool pressure. This force can be of comparable magnitude to the classical Alford force. Prediction and elucidation of the Alford force is also presented. In particular, a new parameter denoted as the blade loading indicator is deduced. This parameter depends only on stage geometry and mean flow and determines the direction of whirl tendency due to tangential blade loading forces in both compressors and turbines. All findings are suitable for incorporation into an overall dynamic system analysis and integration into existing engine design tools. [S0889-504X(00)01604-4]
A Graph Grammar Approach for Structure Synthesis of Mechanisms
Authors: Schmidt Linda C. , Shetty Harshawardhan , Chase Scott C.
Published: July 2002

This paper presents a general graph grammar methodology for structure synthesis of mechanisms. Much of current mechanism design is based on a systematic method popularized by Freudenstein, Mruthyunjaya, and Tsai (among others). A graph grammar is a more natural expression for a method that relies on algebraic abstractions of graph theoretic principles. Our proposed grammar rules add vertices and loops to a start graph to obtain desired structural requirements. A grammar adaptation of an existing linear time algorithm for the detection of isomorphism is presented. Also presented is a specialized grammar for the structure synthesis of Epicyclic Gear Trains. A valid graph grammar for structure synthesis of mechanisms enables both the eventual automation of general atlas construction and atlas construction for customized mechanism classes. [S1050-0472(00)01904-8]
Numerical Simulation on the Flow Structure Around the Injection Nozzles for Pneumatic Dimensional Control Systems
Authors: Yu S. C. M. , Poh H. J. , Tso C. P.
Published: July 2002

A numerical simulation on the airflow exiting from a nozzle in a pneumatic dimensional control system has been conducted using computational fluid dynamics code FLUENT (V. 4.3), which solves finite-difference equations. The important changes occurring in the velocity and pressure fields in the vicinity of the nozzle, as the air exiting from the nozzle and impinging on a flat plate, are the prime objectives of the present studies. Simulation studies were first focus on examining the flow characteristics of the system with the conventional nozzle geometry design. Some comparisons with the experimental results previously obtained by Crnojevic et al. (Crnojevic, C., Roy, G., Bettahar, A., and Florent, P., “The Influence or the Regulator Diameter and Injection Nozzle Geometry on the Flow Structure in Pneumatic Dimensional Control Systems,” ASME J. Fluids Eng., 119, pp. 609–615) were also made. Further simulation studies were conducted with particular attention to a more efficient nozzle geometry. It was found that a divergent type of nozzle design could effectively eliminate the flow separation regions within the nozzle head. By allowing the divergent angle of the nozzle head (α) to vary (from zero to about 25 degrees), a more extensive and sensitive measurement range can be achieved at a given pressure regulator diameter to nozzle diameter ratio. [S0098-2202(00)02404-4]
Heat Treatment of Metal Surfaces by a Conformal Electron Beam
Authors: Liu Shengyi , Dougal Roger A. , Lyons Jed S.
Published: July 2002

The electron beam formed between a conformal plasma cathode and a metal workpiece can be used to heat treat the workpiece. Analyses of the electron energy deposition profiles, heat conduction rates, and austinitizing rates show that it is possible to heat the entire surface of an object to a depth of ∼1 mm within microseconds, to hold the temperature above the austinitizing critical point in the near-surface volume without melting the surface for milliseconds, and to self-quench rapidly. This leads to the prospect of surface hardening of metals by a conformal electron beam.
Gas-Liquid Distribution in the Developing Region of Horizontal Intermittent Flows
Authors: Fossa M.
Published: July 2002

Experiments have been carried out to analyze the evolution of the air/water flow structure along a horizontal 60 mm i.d. straight pipe. Plug and slug flow regimes were observed. In order to investigate the local structure of the flow, dynamic void fraction measurements have been performed by means of ring impedance probes. From dynamic void fraction measurements the mean void fraction values, the probability distributions of void, the liquid film height in the gas cavities and the slug frequencies have been evaluated. The analysis of the results showed that the flow structure deeply modifies along the pipe and that minor effects have to be ascribed to gas injection mode. The examination of the probability distribution function enabled the identification of the operating conditions at which the transition occurs, thus making it possible to propose a new objective criterion of identification.
Catalytic Combustion of Pre-Vaporized Liquid Fuel
Authors: Arai Masataka , Amagai Kenji , Mogi Toshio
Published: July 2002

Fundamental characteristics of the catalytic combustion of vaporized kerosene spray were experimentally investigated. This study is a part of the development of a ceramic gas turbine engine for automobiles. Kerosene was used as a test fuel and its spray was injected from a swirl atomizer into a hot air stream. The inlet air temperature was elevated up to 900 K to vaporize the kerosene spray. Premixed gas of air and kerosene vapor was introduced into the catalyst. The total equivalence ratio was controlled from ϕ=0.18–0.32. The palladium catalyst was supported on a cordierite honeycomb monolith. Catalytic combustion phenomena were categorized in three typical states: (a) state of partial reaction in the catalytic monolith, (b) state of homogeneous reaction in the monolith, (c) state of homogeneous reaction with a blue flame supposed on the monolith. A parabolic shape blue flame in the state of (c) appeared downstream of the monolith. This flame was very stable and its temperature was relatively low compared with conventional premixed flames of hydrocarbon fuel because the equivalence ratio was much lower than those of premixed flames. The distance from the monolith to the ignition point of this flame became short with a rise of the inlet air temperature, even if the volumetric airflow rate increased with the air temperature. Spontaneous emission spectra of radiation from the blue flame were measured. Strong spectral peaks of OH, CH, and CO+ radicals were observed in the spectra. This spectral structure was quite different from that of a blue flame of premixed propane.
Some Considerations on the Electrolysis of Water from Sodium Hydroxide Solutions
Authors: Fletcher Edward A.
Published: July 2002

The unusually high solubilities and thermal coefficients of solubility of the alkali metal hydroxides make them attractive candidates for high-temperature electrolytic processes to produce high-pressure hydrogen. The feasibility of using strong sodium hydroxide (to keep down the saturation pressure of the condensed phase) electrolysis (to facilitate the separation of the hydrogen from oxygen over a liquid phase) at high temperatures (to increase the energy efficiency by substitution of process heat for electric power) and to increase the production rate in a given cell (by increasing the specific conductance of the working fluid) is explored and discussed. Suggestions are made for future research.
Unsteady Flow and Whirl-Inducing Forces in Axial-Flow Compressors: Part II—Analysis
Authors: Ehrich F. F. , Spakovszky Z. S. , Martinez-Sanchez M. , Song S. J. , Wisler D. C. , Storace A. F. , Shin H.-W. , Beacher B. F.
Published: July 2002

An experimental and theoretical investigation was conducted to evaluate the effects seen in axial-flow compressors when the centerline of the rotor becomes displaced from the centerline of the static structure of the engine, thus creating circumferentially nonuniform rotor-tip clearances. This displacement produces unsteady flow and creates a system of destabilizing forces, which contribute significantly to rotor whirl instability in turbomachinery. These forces were first identified by Thomas (1958. Bull. AIM, 71, No. 11/12, pp. 1039–1063.) for turbines and by Alford (1965. J. Eng. Power, Oct., pp. 333–334) for jet engines. In Part I, the results from an experimental investigation of these phenomena were presented. In this Part II, three analytic models were used to predict both the magnitude and direction of the Thomas/Alford force in its normalized form, known as the β coefficient, and the unsteady effects for the compressors tested in Part I. In addition, the effects of a whirling shaft were simulated to evaluate differences between a rotor with static offset and an actual whirling eccentric rotor. The models were also used to assess the influence of the nonaxisymmetric static pressure distribution on the rotor spool, which was not measured in the experiment. The models evaluated were (1) the two-sector parallel compressor (2SPC) model, (2) the infinite-segment-parallel-compressor (ISPC) model, and (3) the two-coupled actuator disk (2CAD) model. The results of these analyses were found to be in agreement with the experimental data in both sign and trend. Thus, the validated models provide a general means to predict the aerodynamic destabilizing forces for axial flow compressors in turbine engines. These tools have the potential to improve the design of rotordynamically stable turbomachinery.
Effect of Loading Rate on Fracture Morphology in a High Strength Ductile Steel
Authors: Venkert A. , Guduru P. R. , Ravichandran G.
Published: July 2002

Fracture experiments in a high-strength ductile steel (2.3Ni-1.3Cr-0.17C) were conducted under static and dynamic loading conditions in a three-point bend and a one-point bend configurations. A qualitative description of the influence of loading rate on the microscopic features of the fracture surfaces and their role in the fracture initiation process was considered. The fracture surfaces consist of tunneled region and shear lips. The size of the shear lips increases with increasing loading rate and is characterized by micro-voids and cell structures. The tunneled region consists of large voids and micro-voids that coalesce by impingement. At high loading rates, localized molten zones are observed at the tunnel-shear lip interface.
Studies on a Horizontal Axis Wind Turbine With Passive Pitch-Flap Mechanism (Performance and Flow Analysis Around Wind Turbine)
Authors: Shimizu Yukimaru , Kamada Yasunari
Published: July 2002

This paper describes the development of a passive system to control the output power of a horizontal axis wind turbine. This pitch-flap coupling mechanism can reduce rotor power above rated wind speed. This mechanism has two kinds of blade motions: the flapping and the pitching motions. In this paper, braking effects are investigated experimentally. It is found that the breaking effect is improved when the ratio of pitch to flap motions is large. Also, the flow pattern around the wind turbine is investigated. It is found that the braking effects are caused by a couple of ring vortices.
Progressive Cracking of a Multilayer System Upon Thermal Cycling
Authors: Begley M. R. , Evans A. G.
Published: July 2002

This article considers progressive cracking upon thermal cycling of a thin multilayer on a thick substrate. The prototypical system comprises a thin elastic layer of a dielectric material above another thin metal interconnect layer attached to a silicon substrate. Residual stresses exist because of the thermal expansion misfit and due to deposition. Putative fabrication flaws are presumed to be present in the dielectric. When activated by residual stresses these flaws can induce cracks that channel along the dielectric. Conditions that induce yielding of the metal upon initial cooling are shown to exacerbate this phenomenon. Moreover, subsequent thermal cycling may induce ratcheting, wherein cracks develop progressively due to repeated yielding of the metal layer. The roles of initial stress, cyclic temperature amplitude, and interconnect yield strength in these phenomena are investigated using finite element models which explicitly account for cyclic yielding. The most deleterious situation is found to be that wherein the entire metal layer reaches yield at some stage during the temperature cycle. Several scenarios relevant to semiconductor devices are considered.
A Nonlinear Generalized Maxwell Fluid Model for Viscoelastic Materials
Authors: Corr D. T. , Starr M. J. , Vanderby, R. , Best T. M.
Published: July 2002

A nonlinear Maxwell fluid model consisting of a linear dashpot in series with a parallel arrangement of a linear spring and a second-order nonlinear spring, was developed. This configuration provides the flexibility necessary to describe both the stiffening and the softening responses of some viscoelastic materials. A noteworthy feature of the model is that under constant rate displacement, the force equation can be solved in closed form, thereby providing a continuous, exact general solution.
Jet Impingement Boiling From a Circular Free-Surface Jet During Quenching: Part 2—Two-Phase Jet
Authors: Hall David E. , Incropera Frank P. , Viskanta Raymond
Published: July 2002

A proposed technique for controlling jet impingement boiling heat transfer involves injection of gas into the liquid jet. This paper reports results from an experimental study of boiling heat transfer during quenching of a cylindrical copper specimen, initially at a uniform temperature exceeding the temperature corresponding to maximum heat flux, by a two-phase (water-air), circular, free-surface jet. The second phase is introduced as small bubbles into the jet upstream of the nozzle exit. Data are presented for single-phase convective heat transfer at the stagnation point, as well as in the form of boiling curves, maximum heat fluxes, and minimum film boiling temperatures at locations extending from the stagnation point to a radius of ten nozzle diameters. For void fractions ranging from 0.0 to 0.4 and liquid-only velocities between 2.0 and 4.0 m/s 11,300⩽Red,fo⩽22,600, several significant effects are associated with introduction of the gas bubbles into the jet. As well as enhancing single-phase convective heat transfer by up to a factor of 2.1 in the stagnation region, addition of the bubbles increases the wall superheat in nucleate boiling and eliminates the temperature excursion associated with cessation of boiling. The maximum heat flux is unaffected by changes in the void fraction, while minimum film boiling temperatures increase and film boiling heat transfer decreases with increasing void fraction. A companion paper (Hall et al., 2001) details corresponding results from the single-phase jet.
Optimization-Based Synthesis of Grashof Geared Five-Bar Mechanisms
Authors: Nokleby Scott B. , Podhorodeski Ron P.
Published: July 2002

A quasi-Newton optimization routine and Grashof criteria for geared five-bar mechanisms are used to develop a Grashof five-bar mechanism synthesis routine. Sequential transformations mapping Grashof mechanism parameters satisfying sub-type specific upper and lower constraints are used. Convergence criteria of: (i) objective function value change, (ii) mechanism parameter change, and (iii) task satisfaction are used. These criteria, combined with search restarts, ensure the synthesis of an acceptable mechanism. Example results demonstrate the effectiveness of the routine.
An Experimental Study of Friction During Planar Elastic Impact
Authors: Osakue Edward E. , Rogers Robert J.
Published: July 2002

Low-speed oblique elastic impacts frequently occur in heat exchangers and other equipment having loosely supported tubes or pipes. In order to experimentally study friction during such impacts, a pendulum-type impact apparatus was developed. A hardened steel sphere at the end of the pendulum collides with a flat steel surface for a range of approach velocities and angles. The present investigation examined eight velocities from 8 to 93 mm/s and impact angles (measured from the common normal) of 0 to 75 deg for each velocity. The normal and tangential contact force waveforms were measured using a triaxial piezoelectric force transducer which was dynamically calibrated. As expected, the results show that the tangential force is less than the limiting Amontons-Coulomb friction predictions at low impact angles. Two regimes of stick-slip and gross-slip friction are clearly distinguished by a new friction parameter called the specific traction ratio. Tangential force reversal was observed at low impact angles, indicating local tangential oscillations. The stick-slip results are consistent with a partial-slip model where the contact zone has a central sticking region surrounded by a ring area undergoing slip.