bluuebunny/crossref_metadata_2025 huggingface dataset:
The coupling between scales in shear flows
Authors: Bandyopadhyay Promode R. , Hussain A. K. M. F.
Published: March 2003

In order to explore the relationship between the large- and small-scale motions in turbulent shear flows, a number of flows have been studied based on short-time correlation measurements. The shear flows investigated are boundary layers, plane and axisymmetric mixing layers, plane wakes and the far fields of plane and circular jets. The coupling between the scales has been obtained by correlating the low-frequency component of the u-velocity signal with a signal that is similar to the envelope of the high-frequency part of the velocity signal. The coupling is found to be significant in all flows. Phase reversal across the shear region is found to occur in the boundary layers and the mixing layers only. This is interpreted to mean that in boundary layers and mixing layers, the streamwise extent of the large structure over which the small-scale activity reaches a peak moves at one transverse end of the large structure over which its ensemble averaged u fluctuation is positive to another where it is negative. This phase shift (≂180°) of the location of the peak activity of the small scales with respect to the large structure takes place gradually resulting in a midlayer where the phase difference is about 90°. On the other hand, in the far field of the jets and wakes, all across the layer, the peak activity of the small scales always remains confined to that half of the streamwise extent of the large structure where its ensemble averaged u fluctuation is positive; in the remaining streamwise half of the large structure, the small scales remain dormant.
Universal equilibrium range of turbulence
Authors: Qian J.
Published: March 2003

The variational approach to the closure problem of turbulence theory, reported in an earlier paper, is applied to the study of the universal equilibrium range of turbulence. Two integral equations are derived for two unknown functions, taking account of viscous dissipation. The equation-error method of parameter estimation of control theory is used to obtain the approximate solution of the two integral equations. The resulting energy spectrum for the universal equilibrium range is E(k)=ε2/3k−5/3F(k/kd) with F(x)=1.19(1+5.3x2/3) ×exp(−5.4x4/3). Here ε is the energy dissipation rate and kd is the Kolmogorov wavenumber. The corresponding one-dimensional energy spectrum and dissipation spectrum are calculated and are in agreement with the experimental results. Since F(x) is not a monotonically decreasing function, but has a maximum near x=0.1, the usual experimental values of the Kolmogorov constant will be greater than its theoretical value F(0)≂1.2 and will depend upon the range of k/kd.
Generalized Ohm’s law for plasma including neutral particles
Authors: Kunkel W. B.
Published: March 2003

A simplified derivation is presented for the so-called ‘‘ion slip,’’ i.e., for the relative motion of ions with respect to the fluid center-of-mass motion, which gives rise to an extra term in the generalized Ohm’s law for partially ionized gases. In the usual formulation, this term is shown to be proportional to j⊥, the current density perpendicular to B. This turns out to be valid when the slip is not strongly affected by a pressure gradient of the neutral component. In the opposite limit, i.e., when ■pn dominates the relative motion perpendicular to B, the ion-slip term takes on a simple form again, provided inertial effects are small, i.e., under quasistatic conditions: (ΔE)slip=ηsD (j⊥−jD), where sD≡Ωe Ωimnnn/ (mnnn+mini) (νei+νen) νin is the modified ion-slip coefficient, while jD≡cB×∇(pi+ pe)/B2 denotes the diamagnetic current.
Hamiltonian treatment of ponderomotive interactions in a Vlasov plasma
Authors: Škorić M. M. , ter Haar D.
Published: March 2003

A Hamiltonian formulation of ponderomotive interactions in a Vlasov plasma is presented. Transformation from the rest frame to the oscillation center frame (OCF) is achieved, and a Liouville equation is derived for the low-frequency OCF distribution function; the Hamiltonian in this equation includes the ponderomotive terms. This equation is solved in the adiabatic approximation, the corresponding charge and current densities evaluated, and the first order nonadiabatic correction to the current density is discussed.
External injection into a high-current modified betatron accelerator
Authors: Mako F. , Manheimer Wallace M. , Kapetanakos C. A. , Chernin D. , Sandel F.
Published: March 2003

By axially tapering the current density at each end of an axial pinch, a scheme is developed for injecting electrons across magnetic field lines into a modified betatron accelerator. This scheme produces only a minimal perturbation to the circulating electron beam. The axial pinch provides beam equilibrium in the transverse field and the tapering reduces the nonadiabatic growth of the perpendicular particle velocity from 0.5c to 0.05c for the parameters of the Naval Research Laboratory modified betatron.
Applications of a cell culture system for studying the interaction ofAnaplasmamarginale with tick cells
Authors: Blouin Edmour F. , de la Fuente José , Garcia-Garcia Jose C. , Sauer John R. , Saliki Jeremiah T. , Kocan Katherine M.
Published: March 2003

A cell culture system for the tick-borne rickettsiaAnaplasma marginaleoffers new opportunities for research on this economically important pathogen of cattle.A. marginalemultiplies in membrane-bound inclusions in host cells. Whereas erythrocytes appear to be the only site of infection in cattle,A. marginaleundergoes a complex developmental cycle in ticks and transmission occurs via the salivary glands during feeding. We recently developed a cell culture system forA. marginaleusing a cell line derived from embryos ofIxodes scapularis. Here we review the use of this cell culture system for studying the interaction ofA. marginalewith tick cells. Several assays were developed using theA. marginale/tick cell system. An adhesion assay was developed for the identification of proteins required byA. marginalefor adhesion to tick cells. The effect of antibodies against selected major surface proteins in inhibitingA. marginaleinfection was tested in an assay that allowed further confirmation of the role of surface proteins in the infection of tick cells. A drug screening assay forA. marginalewas developed and provides a method of initial drug selection without the use of cattle. The culture system was used to test for enhancing effects of tick saliva and saliva components onA. marginaleinfection. The tick cell culture system has proved to be a good model for studyingA. marginale–tick interactions. Information gained from these studies may be applicable to other closely related tick-borne pathogens that have been propagated in the same tick cell line.
Campylobactercolonization in poultry: sources of infection and modes of transmission
Authors: Sahin Orhan , Morishita Teresa Y. , Zhang Qijing
Published: March 2003

Since its recognition as a human pathogen in the early 1970s,Campylobacter jejunihas now emerged as the leading bacterial cause of food-borne gastroenteritis in developed countries. Poultry, particularly chickens, account for the majority of human infections caused byCampylobacter. Reduction or elimination of this pathogen in the poultry reservoir is an essential step in minimizing the public health problem; however, farm-based intervention measures are still not available because of the lack of understanding of the ecological aspects ofC. jejunion poultry farms. AlthoughCampylobacteris highly prevalent in poultry production systems, how poultry flocks become infected with this organism is still unknown. Many investigations indicate that horizontal transmission from environmental sources is the primary route of flock infections byCampylobacter. However, some recent studies also suggest the possibility of vertical transmission from breeder to progeny flocks. The transmission of the organism is not well understood, but it is likely to be through both vertical and horizontal transmission and may be affected by the immune status of the poultry host and the environmental conditions in the production system. Intervention strategies forCampylobacterinfection in poultry should consider the complex nature of its transmission and may require the use of multiple approaches that target different segments of the poultry production system.
Nitric oxide, inducible nitric oxide synthase and inflammation in veterinary medicine
Authors: Hunter Robert P.
Published: March 2003

Inflammation is a process consisting of a complex of cytological and chemical reactions which occur in and around affected blood vessels and adjacent tissues in response to an injury caused by a physical, chemical or biological insult. Much work has been performed in the past several years investigating inducible nitric oxide synthase (NOS, EC 1.14.13.39) and nitric oxide in inflammation. This has resulted in a rapid increase in knowledge about iNOS and nitric oxide. Nitric oxide formation from inducible NOS is regulated by numerous inflammatory mediators, often with contradictory effects, depending upon the type and duration of the inflammatory insult. Equine medicine appears to have benefited the most from the increased interest in this small, inflammatory mediator. Most of the information on nitric oxide in traditional veterinary species has been produced using models or naturally occurring inflammatory diseases of this species.
Oviposition by introduced Ophelimus eucalypti (Hymenoptera: Eulophidae) and morphogenesis of female-induced galls on Eucalyptus saligna (Myrtaceae) in New Zealand
Authors: Raman A. , Withers T.M.
Published: March 2003

An Australian gall-inducing eulophid, Ophelimus eucalypti (Gahan) was first recorded on the foliage of Eucalyptus botryoides after it invaded New Zealand in 1987. It has spread throughout the eucalypt plantations in the North Island and in the northern parts of the South Island affecting several species of Eucalyptus in the section Transversaria (subgenus Symphyomyrtus). Because gall-inducing insects usually have extremely narrow host ranges, O. eucalypti that induces galls on E. saligna and E. botryoides is currently recognized as a biotype, O. eucalypti (Transversaria). Heavily galled leaves abscise from the plant. Repeated defoliation led to widespread die-back of susceptible eucalypt species in the 1990s. Female larvae of O. eucalypti induce circular, protruding galls on the leaves of E. botryoides and E. saligna, whereas the males induce pit galls on the same species. The biology of O. eucalypti females and the development of their galls are described. Adult female O. eucalypti antennate the leaf surface before inserting the ovipositor (otherwise concealed within the metasomal apex) into the young host leaf. The egg is inserted at approximately 45° and discharged between differentiating palisade cells. Callus-type cells surround the egg chamber, but cytologically specialized nutritive cells appear once the egg hatches and the larva begins to feed. The gall also differentiates a multi-layered sclerenchymatous tissue around the nutritive tissue. After feeding for many months, the larva pupates and the active nutritive tissue degenerates. The adult wasp emerges after cutting an exit hole through to the outside of the gall. Abscission of heavily galled leaves results in widespread defoliation and loss of growth and vigour in susceptible trees in New Zealand.
Description of the soybean pod gall midge, Asphondylia yushimai sp. n. (Diptera: Cecidomyiidae), a major pest of soybean and findings of host alternation
Authors: Yukawa J. , Uechi N. , Horikiri M. , Tuda M.
Published: March 2003

The soybean pod gall midge is an important pest of soybean in Japan and is known to occur also in Indonesia and China. This gall midge is described from Japan as Asphondylia yushimaisp. n. and is clearly distinguished from its congeners by the arrangement of the lower frontal horns of the pupa and the sequence of the mtDNA COI region. It is concluded that Prunus zippeliana Miquel is a winter host of the soybean pod gall midge since haplotypes of the soybean pod gall midge coincide with those of the Prunus fruit gall midge that produces fruit galls on P. zippeliana. In addition, phenological and distributional information on the two gall midges and on their host plants supports the identification of the winter host. In Japan, the soybean pod gall midge overwinters as a first instar in the fruit galls on P. zippeliana and emerges as an adult from the galls in May. In summer and autumn, the soybean pod gall midge has two or more generations in the pods of soybean, Glycine max (L.) Merrill or wild fabaceous and caesalpiniaceous plants. Thus host alternation by A. yushimai is confirmed. This is the second finding of host alternation by a species of Asphondylia, the first instance being that of Asphondylia gennadii (Marchal) in Cyprus.
The representativeness heuristic in judgements involving entrepreneurial success and failure
Authors: Wickham Philip A.
Published: March 2003

The representativeness heuristic generates a decision‐bias encouraging over‐estimation of the probability of low likelihood events when they are associated with strongly context representative propositions. An experimental investigation into decision making by final year business undergraduates demonstrates that this heuristic operates and consistently affects subjects’ judgement of the probability of probe details about an entrepreneur in the representativeness‐generating context of the future success or failure of a proposed venture by that entrepreneur. The results suggest that the representativeness heuristic could hinder the quality of managerial decision making, especially decisions involving investment in new ventures. Evidence is generated in favour of a specifically cognitive source for this bias as opposed to a semantic mechanism proposed by some workers. This study adds to the growing literature on the representativeness bias in managerial decision making but is believed to be the first to consider it in an entrepreneurial context.
Perspectives on transformational leadership in the Sanhedrin of ancient Judaism
Authors: Langbert Mitchell , Friedman Hershey H.
Published: March 2003

Individuals interested in leadership can learn much from the Nesi’im (presidents) that headed the Sanhedrin. These leaders faced incredible adversity: Hellenists, Sadducees, Greeks, Romans, the destruction of the Temple, religious persecution, and exile. Yet, they still managed to keep the Jewish people together. The article claims that these individuals were transformational leaders. This paper examines the literature of transformational leadership, and the various characteristics, philosophies, sayings, and behavior of the leaders of the Sanhedrin. The philosophies and values of Nesi’im such as Hillel and Gamliel, recorded in the Talmud and Midrash, did what large armies could not have accomplished: destroy the pagan values of the Greeks and Romans. This paper describes how these philosophies might serve as a paradigm or touchstone for the successful leader of today.
Leadership challenges for organisations in the New South Africa
Authors: Denton Mario , Vloeberghs Daniel
Published: March 2003

This article provides an overview of the recent changes and subsequent new challenges for South African organizations in an ongoing rapidly changing environment. In this context we consider the election period of 1994 as a rupture with the past in the history of the SA nation, and a new start of the so‐called “New South Africa”. Based on personal experiences and literature describes the application of and crucial role played by eight important managerial concepts and methods during the transition period for South African organisations. Finally the impact of this radical change and evolution on new challenges for the leadership and the processes of managing transformation is highlighted.
Measuring empowerment
Authors: Pardo del Val Manuela , Lloyd Bruce
Published: March 2003

This paper aims to contribute to the empowerment literature by providing a concrete definition of the topic and thus a way of measuring the empowerment level in organisations. The tool designed to measure empowerment – resulting from the previous theoretical definition – has been proved to be a scale, fulfilling the necessary properties: reliability and validity. It has been tested on a sample of Spanish firms, concluding that it follows a Normal distribution, whereas 20 per cent of the companies apply a less participative style and 20 per cent could be described as empowered. Measuring empowerment not only serves to know how many companies use empowerment practices but also can be used to delve deeper into relationships between empowerment levels and other managerial concepts, such as the effects of empowerment on organisational change, on quality, or even on organisational performance.
The essence of what we do
Authors: Medeiros Norm
Published: March 2003

This article reports on Connexion, OCLC’s new integrated toolset developed as its next generation cataloging system. The author considers the ever‐changing nature of technical services in light of technological evolutions, budget constraints, and the expectations of academic library users. The article also looks at the importance of education for in‐training and practicing catalog librarians.
Reference, access, and use
Authors: Jimerson Randall C.
Published: March 2003

Providing reference and access services for users requires special techniques and knowledge of a repository’s holdings. Archivists need to identify their user clientele and design services for their needs. User studies provide a means to collect valuable information about the clientele. In order to consult manuscripts and archives, users need to have both intellectual and physical access to the materials. Each of these access types requires repository policies and procedures, both to assist users and to protect the rights of donors and third parties who might be affected by disclosure of sensitive information. The reference process usually requires personal interaction and mediation by archival staff, both for security reasons and because of the difficulty of identifying potential sources to meet reference queries. The Internet provides important means of publicizing information about repositories and their collections, but technical and intellectual considerations limit the options for providing an entire records series or manuscript collection on‐line.
Digital anxiety and cooperation in a networked world
Authors: Cox Robert , Onuf Rachel
Published: March 2003

In September, 2000, the Philadelphia Area Consortium of Special Collections Libraries (PACSCL) received a grant from the Gladys Krieble Delmas Foundation to outsource legacy finding aids for conversion into EAD. By working cooperatively and adopting a novel Lancasterian structure in which early participants in the grant assisted later ones, the grantees developed a robust peer to peer network that resulted in the acquisition of significant local experience, and some expertise, in EAD application. We conclude with the proposition that much of the current digital anxiety besetting our profession is misplaced; rather than fall prey to anxiety over the constant need for adaptation to emerging technologies, archivists should concern themselves more with the critical skills of description, arrangement, and interpretation, the traditional archival skills that are in danger of eroding in the new digital world.
Review of the uses and modeling of bitumen from ancient to modern times
Authors: Murali Krishnan and J , Rajagopal KR
Published: March 2003

In this article, we provide a review of the uses of asphalt from ancient to modern times and we discuss the main attempts at mathematically modeling its behavior. We start with a discussion of the various definitions for asphalt and bitumen and discuss briefly some of the many fascinating uses to which they have been put from ancient to modern times. In Section 3 we survey the various attempts at unraveling the chemical structure of asphalt. The description of its physical characteristics, the early constitutive models that have been employed to describe its mechanical response, and the numerous tests to assess its properties are dealt with in Section 4. The next section is devoted to a discussion of the aging of asphalt. In Section 6, after a cursory discussion of the more classical models for asphalt concrete, we introduce the reader to a thermodynamic framework that has been recently put into place for bodies that have multiple natural configurations and use this framework to develop a model for describing the mechanical response of asphalt concrete. We use this model to describe various experiments that have been carried out on asphalt concrete and we find that the predictions of the model agree with experiments sufficiently well. This review article cites 580 references.
Robust Fixture Configuration Design for Sheet Metal Assembly With Laser Welding
Authors: Li Bing , Shiu B. W. , Lau K. J.
Published: March 2003

Fixturing plays an important role in the quality of metal fit-up for sheet metal assembly with laser welding. To reduce the sensitivity of the designed fixture configuration to location fluctuation, this paper provides a quality design of the fixture configuration for sheet metal laser welding. A generic robust design methodology, labeled the two-stage response surface methodology, is developed in the robust design model. The first stage is to find the Robust Design Space (RDS), in which robust solutions with higher degrees of insensitivity reside. Within the RDS, a second-order response surface model can be fitted by a 3k fractional factorial design in the second stage. Based on the resultant response model, the robust fixturing scheme and the influential design locators can be obtained by an optimization and a statistical screening techniques. The degree of metal fit-up is taken as the performance characteristic of the robust design. An example illustrates how the robust design method effectively meets the quality requirements of the fixturing design.
Definition and Application of a Process Flexibility Index
Authors: Kazmer David , Hatch David , Zhu Liang , Roser Christoph , Kapoor Deepak
Published: March 2003

A performance index, Cf, is developed for assessing the flexibility of candidate engineering designs and manufacturing processes at various stages during product development. The index is a ratio of the range of the feasible space to the range of the specification or measured process variation. The process flexibility index complements the process capability index, Cp, to provide a simple and quantitative basis for practicing the principles of axiomatic design. This quantitative measure can be used to support rational product development and manufacturing investment decisions, and clearly illustrates important concepts regarding controllability across conflicting specifications. A high Cp indicates that the design or process can consistently manufacture the product within precisely defined performance specifications. A high Cf indicates that the process can be easily changed to meet diverse performance specifications. The evaluation of Cf requires the mapping of the global feasible space, the solution to which is also discussed.
Transient Flow in Abrasive Suspension Jet Cutting Machines on Pump Shutdown
Authors: Wan S. , Lim G. C.
Published: March 2003

This paper presents an analysis of the transient flow, on pump shut-down, in abrasive suspension jet cutting machines as part of an effort to develop a fine-beam cutting system. The analysis was motivated by a need to clearly understand the problem of line and nozzle clogging, which would be magnified by the higher operating pressures and the use of smaller nozzles for fine-beam systems. Simulation studies show that currently recommended means of avoiding this problem may not be adequate. Using the tools developed for this study, more positive mechanisms and a proposed system to counter this problem were investigated.
Continuum thermomechanics and the clinical treatment of disease and injury
Authors: Humphrey JD
Published: March 2003

Advances in laser, microwave, radio-frequency, and similar technologies have given rise to many new treatments of disease and injury that seek to raise the temperature of cells and tissues to supra-physiologic levels. Copious examples are found in, among other specialties, cardiology, dermatology, gynecology, neurosurgery, oncology, ophthalmology, orthopedics, and urology. Most of the particular clinical procedures are motivated primarily by the availability of a new technology, however, not by an understanding of the underlying biothermomechanics. This article reviews some of the literature on the effects of supra-physiologic temperatures on cells and tissues as well as some of the available mathematical models. Because of the absence of any textbook on biothermomechanics, some basic concepts are included for the interested student. Because of space limitations, however, most research findings are simply stated, and the reader is directed to the relevant papers for details. Finally, because of the desire to attract diverse researchers to the field, open problems are identified. Indeed, it is hoped that this review will generate excitement with regard to the potential of improving health care delivery through the important and challenging field of Continuum Biothermomechanics. There are 177 references cited in this review article.
An Analytical Design Method for Milling Cutters With Nonconstant Pitch to Increase Stability, Part I: Theory
Authors: Budak E.
Published: March 2003

Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with nonconstant pitch angles can be very effective in improving stability against chatter. In this paper, an analytical stability model and a design method are presented for nonconstant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for determination of optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples in the second part of the paper.
An Analytical Design Method for Milling Cutters With Nonconstant Pitch to Increase Stability, Part 2: Application
Authors: Budak E.
Published: March 2003

Chatter stability in milling can be improved significantly using variable pitch cutters. The pitch angles can be optimized for certain chatter frequency and spindle speed ranges using the analytical method presented in the first part of this two-part paper. In this part, the improvement of productivity and surface finish are demonstrated in three example applications. It is shown that chatter stability can be improved significantly even at slow cutting speeds by properly designing the pitch angles. A roughing example demonstrates substantially reduced peak milling forces which allows higher material removal rate.
The Effect of Flexible-Tool Rotation on Regenerative Instability in Machining
Authors: Li Chen-Jung , Ulsoy A. Galip , Endres William J.
Published: March 2003

For rotating-tool machining, such as milling, line boring, and cylinder boring, the tool rotation causes the machining force on each tooth to rotate repetitively relative to the inertial coordinate frame. This is quite different than stationary-tool machining, such as turning or boring with a stationary boring bar, in which the force directions are fixed relative to the inertial frame. Although the subject of stability analysis for rotating tools has been studied extensively in milling, the process is intermittent and hence time varying, which leads to analysis methods that are either analytically approximate or employ time-domain simulation. In this paper nonintermittent machining processes that employ a rotating tool are modeled and analyzed in the rotational coordinates both to simplify the stability analysis and to permit an exact solution. Using rotating-bar boring to illustrate, the analytical results show that the stability limits for boring with a rotating boring bar are quite different from those for boring with a stationary boring bar, and the experimental validation is also provided. Furthermore, the results show a discrepancy to exist between the predicted stability limits for the exact and approximate solutions, especially at low spindle speeds. In both cases an explanation is provided based on the analysis presented.
Ideal Forming Analysis for Random Fiber Preforms
Authors: Dessenberger Richard B. , Tucker Charles L.
Published: March 2003

In resin transfer molding, the manufacture of the fiber preform controls many aspects of part quality. These include defects such as wrinkling and tearing, as well as spatial variations in fiber volume fraction and permeability. We develop a mathematical model and numerical method for analyzing preforming of random fiber mats. The model uses an ideal forming theory, which maps a fiber sheet to the mold surface by minimizing the integral of a formability function over the mold surface. The scalar formability function depends on the local deformation, and exhibits large values under conditions that promote either tearing or wrinkling of the mat. The model is implemented as a finite element simulation for arbitrarily shaped three-dimensional preforms. Results include the shape of the initial fiber sheet, and values of the formability function and the principal stretch ratios over the mold surface. This information is used to predict the presence of defects in the preform. Example calculations are shown for an axisymmetric hat shape and for a box with a flange. The calculation requires a modest amount of input data and, rather than predict the exact result of the forming operation, it shows the best result that is possible. Thus, it is a useful tool in the early stages of part and mold design.
Online Identification of Shearing and Plowing Constants in End Milling
Authors: Junz Wang J.-J. , Zheng C. M.
Published: March 2003

Online methods for the identification of shearing and plowing cutting constants from forces in a single milling operation are presented. By virtue of the analytical nature of the milling force model in the frequency domain, the shearing and plowing constants are expressed, in a linear closed-form equation, in terms of cutter geometry, cutting depths and the Fourier coefficients of the milling forces. Two methods are presented to identify these cutting constants. The first method uses only the first harmonic components of the milling forces, and the second method utilizes the average forces as well as the ratio of the first harmonic forces. Limitations on the cutting conditions for each identification method are discussed. The accuracy and consistency of these two methods in extracting the shearing and plowing constants from a single set of force measurements are verified through simulation and milling experiments.
Modeling and Prediction of Hole Profile in Drilling, Part 1: Modeling Drill Dynamics in the Presence of Drill Alignment Errors
Authors: Gupta Khagendra , Ozdoganlar O. Burak , Kapoor Shiv G. , DeVor Richard E.
Published: March 2003

A dynamic deflection model that incorporates the effect of the alignment errors that arise when a drill is held in the spindle assembly has been developed. The drill is modeled as an Euler-Bernoulli beam with clamped-free end conditions. Thrust and radial forces were applied at the free end of the beam. The mechanistic model used to predict these forces has been enhanced to incorporate the effect of the alignment errors and drill vibrations. A method has been outlined to measure these alignment errors. The mechanistic model demonstrates the ability to predict the drill vibrations and the radial forces within 6 percent of the measured vibrations and forces. The effect of these alignment errors on the drill vibrations and the radial forces has also been studied.
Modeling and Prediction of Hole Profile in Drilling, Part 2: Modeling Hole Profile
Authors: Gupta Khagendra , Ozdoganlar O. Burak , Kapoor Shiv G. , DeVor Richard E.
Published: March 2003

A hole profile model that integrates the dynamics of the drill in the presence of alignment errors, the drill wandering, and the drill margin-hole wall interaction has been developed. The ultimate profile of the hole is generated by the vibrations of the drill at its tip due to its dynamics and wandering, and by the continual updating of the already generated surface to account for any potential drill margin-hole wall interaction. The model predicts the lobbing pattern of the hole in close agreement to that observed during the experiments. The effect of the drill dynamics in the presence of alignment errors, drill wandering, drill margin-hole wall interaction as well as the individual effect of the alignment errors (α, ϕ, and γ) has been studied.
Modeling the Effect of Tramp Oil Contamination on Selective Component Depletion in Metalworking Fluid Systems
Authors: Eppert Joseph J. , Rajagopalan N. , DeVor Richard E. , Kapoor Shiv G.
Published: March 2003

Functional component depletion and physical interaction of contaminants with the machining process are thought to be the primary determinants of metalworking fluid useful life. An oil/water partition coefficient and mass balance based model is derived that is capable of accounting for the effect of tramp oil induced extraction of metalworking fluid components. After developing general expressions for the predictive model, the magnitude of extraction for a synthetic metalworking fluid is investigated. The model is then used to predict system concentrations over time in the presence of such metalworking fluid contaminants and is verified via laboratory experimentation and an industrial case study. The partition coefficient/mass balance modeling procedure is further utilized to determine the amounts and frequency required for tankside addition of metalworking fluid components, while accounting for depletion by the tramp oil mechanism.
Probe Radius Compensation of Workpiece Localization
Authors: Xiong Zhenhua , Li Zexiang
Published: March 2003

Workpiece localization has direct relations with many manufacturing automation applications. In order to gain accurate workpiece measurement by on-machine measurement system or coordinate measuring machines (CMM), the touch trigger probe is widely adopted. In spite of the high repeatability of the touch trigger probe, there are still error sources associated with the probe. In this paper, we will focus on probe radius compensation. We first show the sources of probe radius error. Then, several compensation methods in related papers are reviewed. After that, a new radius compensation method is proposed in this paper. Simulation and experimental results of probe radius compensation by different methods are given. It is shown that our proposed method has the best performance both in terms of compensation accuracy and computational time. The method is also implemented in a computer aided setup (CAS) system.
Future Directions in the Study of Nonconservative Water Wave Systems
Authors: Tulin Marshall P.
Published: March 2003

A few future directions and challenges in wave research are briefly discussed including Numerical Experiments as in the treatment of splashing waves, and topics in the Mechanics of Ocean Waves, especially in their nonlinear, nonconservative reality. Breaking waves are featured.
Wave Trapping by Axisymmetric Concentric Cylinders
Authors: Shipway B. J. , Evans D. V.
Published: March 2003

It is both a pleasure and privilege to present a paper on the uniqueness of linearized water waves at this mini-symposium in honor of Professor John Wehausen whose classic review article Surface Waves (with E. V. Laitone) has done so much to influence workers in the field in the forty-two years since its publication. The question of the uniqueness of solutions to the linearized water wave equations was settled once and for all in a paper in the Journal of Fluid Mechanics by M. McIver. She constructed a solution for the motion between a pair of fixed rigid surface-piercing cylinders in two dimensions which decayed at large distances from the cylinders. Soon after she was joined by P. McIver in producing an axisymmetric example in the form of a fixed rigid surface-piercing toroid of a special shape which supported an oscillatory motion in its interior fluid region whilst the motion in the exterior region decayed to zero. This wave trapping effect or non-uniqueness occurred for a particular relation between the wave frequency and the toroid geometry. In the present paper we show that such a phenomenon can occur for simple geometries also. In particular we show that wave trapping can occur in the annular region between two partially immersed vertical concentric circular cylindrical shells for particular values of radii and frequencies.
Limiting Forms of Internal Solitary Waves
Authors: Maltseva Janna L.
Published: March 2003

High sensitivity of nonlinear wave structures in the weakly stratified fluid with respect to small perturbations of density in the upstream flow was pointed out by Benney and Ko, Stud. Appl. Math., 59(3), pp. 187–199. In the present paper the influence of fine scale stratification on one of the limiting forms, namely the plateau-shaped solitary waves, is analyzed. It is demonstrated that new limiting forms of solitary waves are possible in the case of continuous stratification close to a linear or an exponential one.
Intelligent Model-based Optimization of the Surface Grinding Process for Heat-Treated 4140 Steel Alloys With Aluminum Oxide Grinding Wheels
Authors: Lee Cheol W. , Choi Taejun , Shin Yung C.
Published: March 2003

This paper presents implementation results of surface grinding processes based on the model-based optimization scheme proposed by Lee and Shin (Lee, C. W., and Shin, Y. C., 2000 “Evolutionary Modeling and Optimization of Grinding Processes,” Int. J. Prod. Res. 38(12), pp. 2787–2813). In order to accomplish this goal, process models for grinding force, power, surface roughness, and residual stress are developed based on the generalized grinding model structures using experimental data. The time-varying characteristics due to wheel wear are also investigated in order to determine the optimal dressing interval. Grinding optimization is considered as constrained nonlinear optimization problems with mixed-integer variables and time-varying characteristics in this study. Case studies are performed with various optimization objectives including minimization of grinding cost, minimization of cycle time, and process control. The optimal process conditions determined by the optimization scheme are validated by experimental results.
Radial Error Feedback Control for Bar Turning in CNC Turning Centers1
Authors: Fan Chun , Collins, Emmanuel G. , Liu Charlie , Wang Ben
Published: March 2003

In-process measurement and control of CNC machines can improve machining accuracy while increasing productivity and eliminating waste in a cost effective way. This paper describes an in-process measurement and control system called radial error feedback control (REFC) for bar turning in CNC turning centers. REFC was designed to compensate for the radial error due to the time-varying bar deflection caused by the cutting force, which moves along the bar at a constant velocity. In a dry cutting environment, a noncontact laser sensor was used to directly measure the radial error of the workpiece while it is being cut. To compensate for the radial error, a gain-scheduled Kalman filter for prediction together with PI control law was designed, based on a time-varying model of the deflection of the bar. Analytical modelling (using classical beam vibration theory) was employed to develop a simple model for the bar bending. For non-uniform bars finite element modelling can be used. Experimental results show that the dimensional and geometric accuracy of the workpiece is substantially improved by this radial error feedback control technique.
Sliver Generation Reduction in Trimming of Aluminum Autobody Sheet
Authors: Li Ming
Published: March 2003

Aluminum autobody sheets produce appreciable amounts of slivers during trimming operations when trimmed with dies conventionally designed for steel sheets. The slivers can be carried through downstream processes and cause damage to the surface of formed parts resulting in costly manual repair. This paper reports a systematic experimental study at both the macro- and micro-scale of the sliver generation problem with relation to cutting angle, clearance, and blade sharpness. It is concluded that slivers can be reduced or even eliminated by modifying the current trimming tools designed for steel sheets. The most striking finding is that the conventional wisdom of 0-degree cutting conditions generate the largest amount of slivers for aluminum alloy sheets. With proper cutting angles, trimming aluminum autobody sheets can actually be more robust than that for steel sheets—the clearances can be less restrictive and tools may require much less frequent sharpening. The microscopic investigation traced the origins of slivers and revealed the mechanisms of sliver generation. The paper demonstrates that the integration of material microstructure and mechanics is very beneficial for solving a significant manufacturing problem and can greatly improve the process of shearing aluminum alloy autobody sheet.
Total C4B Deficiency Due to Gene Deletion and Gene Conversion in a Patient with Severe Infections
Authors: Jaatinen Taina , Lahti Meri , Ruuskanen Olli , Kinos Riikka , Truedsson Lennart , Lahesmaa Riitta , Lokki Marja-Liisa
Published: March 2003

Deficiencies of the early components of the classical complement pathway impair the actions of innate and humoral immunity and may lead to increased susceptibility to infections. We have studied the genetic basis of total C4B deficiency in a Finnish patient with recurrent meningitis, chronic fistulas and abscesses. The maternal chromosome carried a four-gene deletion including the C4B gene, and a conversion from C4B to C4A gene was found on the paternal chromosome resulting in complete deficiency of C4B. In the converted C4A gene, mutation screening did not reveal any amino acid changes or prominent mutations, yet a large number of nucleotide variations were found. Further, the patient was heterozygous for structural deficiency of mannan binding lectin (MBL) associating with medium levels of serum MBL. Our data provides new information on the genetic instability of the C4 gene region, and on the association of homozygous C4B deficiency and variant MBL genotype with increased susceptibility to recurrent and chronic infections. Importantly, plasma therapy induced a prompt clinical cure with long-term effects.
Levels of Antibodies Specific to Tetanus Toxoid,Haemophilus influenzaeType b, and Pneumococcal Capsular Polysaccharide in Healthy Children and Adults
Authors: Schauer Uwe , Stemberg Frank , Rieger Christian H. L. , Büttner Wolfgang , Borte Michael , Schubert Simone , Möllers Helga , Riedel Frank , Herz Udo , Renz Harald , Herzog Wilhelm
Published: March 2003

Antibody levels specific for capsular polysaccharides ofStreptococcus pneumoniaeandHaemophilus influenzaetype b (Hib) and for tetanus toxoid were measured in serum samples of 386 age-stratified subjects. The study group consists of healthy adult blood donors and hospitalized children undergoing elective surgery, excluding individuals with a history of infection. In children, anti-tetanus toxoid antibody levels displayed two peaks of 1.20 IU/ml (20.4 mg/liter) and 1.65 IU/ml (28.1 mg/liter) related to the schedule of routine childhood immunization in the first year and at 8 years of age. Eighty percent of the antibodies are of the immunoglobulin G1 (IgG1) isotype. For pneumococcal capsular polysaccharide (PCP), the specific antibody levels represent the acquisition of natural immunity. The initial concentration of 9.2 mg/liter was low in infancy (0.5 to 1 years of age) and remained low until 3 to 4 years of age (14.6 mg/liter). During this period PCP antibodies were almost 100% of the IgG2 subclass. Thereafter, IgG anti-PCP antibody titers increased steadily to adult levels (59.5 mg/liter). The data are intended to provide reference ranges to aid in the interpretation of specific antibody determinations in the clinical setting.
Clearance of Virulent but Not AvirulentRhodococcus equifrom the Lungs of Adult Horses Is Associated with Intracytoplasmic Gamma Interferon Production by CD4+and CD8+T Lymphocytes
Authors: Hines Stephen A. , Stone Diana M. , Hines Melissa T. , Alperin Debby C. , Knowles Donald P. , Norton Linda K. , Hamilton Mary J. , Davis William C. , McGuire Travis C.
Published: March 2003

Rhodococcus equiis a gram-positive bacterium that infects alveolar macrophages and causes rhodococcal pneumonia in horses and humans. The virulence plasmid ofR. equiappears to be required for both pathogenicity in the horse and the induction of protective immunity. An understanding of the mechanisms by which virulentR. equicircumvents protective host responses and by which bacteria are ultimately cleared is important for development of an effective vaccine. Six adult horses were challenged with either virulentR. equior an avirulent, plasmid-cured derivative. By using a flow cytometric method for intracytoplasmic detection of gamma interferon (IFN-γ) in equine bronchoalveolar lavage fluid (BALF) cells, clearance of the virulent strain was shown to be associated with increased numbers of pulmonary CD4+and CD8+T lymphocytes producing IFN-γ. There was no change in IFN-γ-positive cells in peripheral blood, suggesting that a type 1 recall response at the site of challenge was protective. The plasmid-cured strain ofR. equiwas cleared in horses without a significant increase in IFN-γ-producing T lymphocytes in BALF. In contrast to these data, a previous report in foals suggested an immunomodulating role forR. equivirulence plasmid-encoded products in downregulating IFN-γ expression by equine CD4+T lymphocytes. Intracytoplasmic detection of IFN-γ provides a method to better determine whether modulation of macrophage-activating cytokines by virulent strains occurs uniquely in neonates and contributes to their susceptibility to rhodococcal pneumonia.
Simple Method To Distinguish between Primary and Secondary C3 Deficiencies
Authors: Pereira de Carvalho Florido Marlene , Ferreira de Paula Patrícia , Isaac Lourdes
Published: March 2003

Due to the increasing numbers of reported clinical cases of complement deficiency in medical centers, clinicians are now more aware of the role of the complement system in the protection against infections caused by microorganisms. Therefore, clinical laboratories are now prepared to perform a number of diagnostic tests of the complement system other than the standard 50% hemolytic component assay. Deficiencies of alternative complement pathway proteins are related to severe and recurrent infections; and the application of easy, reliable, and low-cost methods for their detection and distinction are always welcome, notably in developing countries. When activation of the alternative complement pathway is evaluated in hemolytic agarose plates, some but not all human sera cross-react to form a late linear lysis. Since the formation of this linear lysis is dependent on C3 and factor B, it is possible to use late linear lysis to routinely screen for the presence of deficiencies of alternative human complement pathway proteins such as factor B. Furthermore, since linear lysis is observed between normal human serum and primary C3-deficient serum but not between normal human serum and secondary C3-deficient serum caused by the lack of factor H or factor I, this assay may also be used to discriminate between primary and secondary C3 deficiencies.