bluuebunny/crossref_metadata_2025 huggingface dataset:
Employee assistance programmes in the UK oil industry: an examination of current operational practice
Authors: Gammie Bob
Published: July 2002

Examines current operational practice in the UK oil industry in relation to employee assistance programmes (EAPs) ‐ a voluntary and confidential workplace counselling and support service. Suggests that the industry contains a high number of potential stressors relating to the environment in which it operates, the nature of the work itself, and the potentially hazardous journey to the workplace. Describes a case‐study methodological approach using semi‐structured in‐depth interviews. The results indicate that EAPs have been initiated as part of health programmes within the firms and that economic factors have not played a significant part. The usage of the service has been surprisingly low compared to other empirical findings. Little examination or evaluation has been undertaken. No firm could therefore quantify success and firms did not consider this necessary as long as some use was being made of the service.
Using team – individual reward and recognition strategies to drive organizational success
Authors: Cacioppe Ron
Published: July 2002

Discusses the value of team and individual reward strategies and how these can be used to contribute to organisational change and success. A review of team effectiveness and models of teamwork are first discussed so that team rewards are understood as important motivators to accomplishing organisational objectives. Four factors need to be considered in establishing team‐based rewards: the stages of a team life cycle, reward and recognition categories, the type of teams and the culture of the team and organisation. Forty‐four specific reward tools are described which can be used for individual or team incentives. Comprehensive matrices are put forward which can be used to determine which tool should be used at which stage in a team’s life cycle and with which type of team. Finally, the implementation cost, evaluation of team reward systems is considered.
Testing Proportionality, Symmetry and Exclusiveness in Long‐run PPP
Authors: Moosa Imad A.
Published: July 2002

Present some empirical evidence on long‐run Purchasing Power Parity (PPP) using a sample of annual data covering the period 1900‐1987. Three exchange rates are used in the analysis: the dollar, yen and French franc against the pound. It is shown that PPP does hold in the long run and that is some evidence for the proportionality and symmetry restrictions. Evidence for exclusiveness is mixed and the results are influenced by model specification. Estimates of error‐correction models show that there are substantial short‐run deviation from PPP that take two to three years to correct.
FANUC ‐ the planning and development of a highly advanced robotized production system for servo motors
Authors: Uchida Hiroyuki , Amemiya Youichi
Published: July 2002

States that 16 years have passed since the commencement of operation of FANUC’s existing factory for assembling servo motors, the company’s staple products. The factory has attained a monthly production capacity of 25,000 units through persistent efforts to improve robotization and automation. To further improve productivity and enhance production capacity, FANUC recently constructed a new servo motor assembly factory. It employs the most up‐to‐date robots and linear motors. The new factory has a monthly production capacity of 50,000 units. This article introduces the new factory, focusing on the features of the physical distribution and production technologies it uses.
Human body 3D imaging by speckle texture projection photogrammetry
Authors: Paul Siebert J. , Marshall Stephen J.
Published: July 2002

Describes a non‐contact optical sensing technology called C3D that is based on speckle texture projection photogrammetry. C3D has been applied to capturing all‐round 3D models of the human body of high dimensional accuracy and photorealistic appearance. The essential strengths and limitation of the C3D approach are presented and the basic principles of this stereo‐imaging approach are outlined, from image capture and basic 3D model construction to multi‐view capture and all‐round 3D model integration. A number of law enforcement, medical and commercial applications are described briefly including prisoner 3D face models, maxillofacial and orofacial cleft assessment, breast imaging and foot scanning. Ongoing research in real‐time capture and processing, and model construction from naturally illuminated image sources is also outlined.
Benchmarking methodologies applied to UK facilities management
Authors: Massheder Keith , Finch Edward
Published: July 2002

The use of benchmarking is regarded by many as a panacea to modern day business problems. Irrespective of what business you are in, or the financial state of your business; proponents of the procedure insist benchmarking, if correctly applied, ensures organizations are able to gain the competitive edge necessary in today’s business world. But how can this technique be usefully exploited in the facilities management arena? The theory suggests that a structured approach to the benchmarking of facilities management will give organizations the competitive edge necessary to survive in the worldwide market. But what happens in practice? Is benchmarking used by major companies, and if so, is it used by facilities managers responsible for the company’s office buildings? If it is, is it successful and, more importantly, is it being correctly employed? This paper forms part of a two‐part report which seeks to answer these questions, taking account of the broad range of company sizes and activities who use office space, looking specifically at the UK situation.
A numerical study of pore‐fluid, thermal and mass flow in fluid‐saturated porous rock basins
Authors: Zhao Chongbin , Hobbs B.E. , Baxter K. , Mühlhaus H.B. , Ord A.
Published: July 2002

We present a numerical methodology for the study of convective pore‐fluid, thermal and mass flow in fluid‐saturated porous rock basins. In particular, we investigate the occurrence and distribution pattern of temperature gradient driven convective pore‐fluid flow and hydrocarbon transport in the Australian North West Shelf basin. The related numerical results have demonstrated that: (1) The finite element method combined with the progressive asymptotic approach procedure is a useful tool for dealing with temperature gradient driven pore‐fluid flow and mass transport in fluid‐saturated hydrothermal basins; (2) Convective pore‐fluid flow generally becomes focused in more permeable layers, especially when the layers are thick enough to accommodate the appropriate convective cells; (3) Large dislocation of strata has a significant influence on the distribution patterns of convective pore‐fluid flow, thermal flow and hydrocarbon transport in the North West Shelf basin; (4) As a direct consequence of the formation of convective pore‐fluid cells, the hydrocarbon concentration is highly localized in the range bounded by two major faults in the basin.
A 12‐node hybrid stress brick element for beam/column analysis
Authors: Sze K.Y. , Lo S.H.
Published: July 2002

In this paper, a hybrid stress 12‐node brick element is presented. Its assumed stress field is derived by first examining the deformation modes of a geometrically regular element and then generalizing to other element configurations using tensorial transformation. The total number of stress modes is 30 which is minimal for securing the element rank. To reduce the computational cost associated with the fully populated flexibility matrix, the admissible matrix formation is employed to induce high sparsity in the matrix. Popular beam bending benchmark problems are examined. The proposed elements deliver encouraging accuracy.
International relationship marketing ‐ The importance of psychic distance
Authors: Conway Tony , Swift Jonathan S.
Published: July 2002

This conceptual paper outlines why, when working in the international as opposed to the domestic environment, the success of a relationship marketing strategy is heavily dependent on levels of psychic distance. The higher the level of psychic distance, the greater the time and effort required to develop successful business relationships. At the different stages of relationship development, different variables of psychic distance assume relatively greater levels of importance which are likely to have implications for the implementation of a relationship marketing strategy.
Fill this in before you go
Authors: Dawson Ruth
Published: July 2002

The most commonly used mechanism for evaluating training courses is
the evaluation sheet. Although held in low esteem, it is used routinely
throughout the public and private sectors to evaluate training courses.
Describes a study of such sheets, followed by guidelines for improving
their construction and use. Makes suggestions for redesign in order to
give much better information.
Administering the adult and continuing education programme in a free market economy
Authors: Michael Steve O. , Hamilton Awilda , Dorsey Marlene R.
Published: July 2002

Describes a free market economy as a competitive, self‐regulating market. In this environment, marketing becomes a powerful instrument for matching products and services to people′s needs. The competitive nature of the market necessitates a continuous exploration of changes in people′s needs and a constant adaptation of the organization and its output to these changes. The success of this adaptation enhances product or service quality and ensures institutional survival. Explains that adult and continuing education can become more effective by adopting marketing strategies, and provides important marketing strategies that may be found relevant in the administration of adult and continuing education programmes under a free market economy.
Sewing needle penetration force study
Authors: Gotlih Karl
Published: July 2002

Demonstrates the modelling of the kinetic process when the sewing needle enters the fabric. To get an adequate mechanical model of the given problem, the function ‐ the mathematical model ‐ of the penetration force with respect to the fabric, the needle and the mechanism in the sewing machine must be developed. The fabric was modelled as a combination of warp and weft threads. Each thread from the fabric is modelled as an ideal elastic Hook’s material. Outlines the restrictions which needed to be made to get the mathematical model of the problem.
Educational development and reformation in Malaysia: past, present and future
Authors: Haji Ahmad Rahimah
Published: July 2002

Discusses educational development, focussing on curriculum changes and issues affecting the change in Malaysia and perspectives for the future. Begins with an introduction that describes the school system in general, followed by a description of educational and curriculum development from independence to the present, highlighting the most current trends and changes Malaysia is undertaking. Concludes with discussions on the issue of values education which is being taught in schools and the efforts of the government to mould a united Malaysian nation with Malaysian values, as well as an overview of the current incentives and future perspectives for greater use of technology in the classroom.
Interactive, inter‐organizational innovations in electronic commerce
Authors: Elliot Steve , Loebbecke Claudia
Published: July 2002

Electronic commerce has been recognised as a source of fundamental change to the conduct of business. Exploitation by business of this innovative approach to payments will necessitate wide‐scale adoption of new processes and technologies and may require new thinking on how organizations adopt innovations. Primarily, these innovations will be interactive and inter‐organizational, i.e. a successful cash substitute will require the concurrent participation of many different organizations, as well as consumers. Current theoretical models of adoption may not cater for this type of innovation. This paper compares four diverse pilot implementations of smart‐card payment systems with Rogers’ (1995) attributes of innovations, adoption processes and adoption decision approaches for organizations. In general, Rogers’ models do not reflect the levels of complexity and diversity found in practice. Extensions of the models are proposed.
Combined convection in non‐Newtonian fluids along a nonisothermal vertical plate in a porous medium
Authors: Mansour M.A. , Subba Reddy Gorla Rama
Published: July 2002

The problem of combined convection from vertical surfaces in a porous medium saturated with power‐law type non‐Newtonian fluids along a non‐isothermal vertical plate is investigated. The transformed conservation laws were solved numerically for the case of variable surface heat flux conditions. Results for the details of the velocity and temperature fields as well as the Nusselt number have been presented.
Numerical study of three‐dimensional incompressible thermal flows in complex geometries
Authors: Ramaswamy Balasubramaniam , Moreno Rafael
Published: July 2002

In part I uses an iterative point successive over‐relaxation (PSOR) finite difference scheme to solve the coupled unsteady Navier‐Stokes and energy equations for incompressible, viscous and laminar flows in their primitive variable form. Presents the details concerning the derivation of the solution scheme, as well as details on its computer implementation. For validation purposes, includes the results of the two‐dimensional and three‐dimensional benchmark problem of natural convection in a cavity with differentially heated vertical walls. Benchmark computations have been performed for a Prandtl number of 0.71, and different values of the Rayleigh number ranging between 103 and 106 depending on the problem. By comparison with other approaches in the literature, the scheme has been found to be accurate even for large Rayleigh numbers.
Coupling heat conduction, radiation and convection in complex geometries
Authors: Rupp I. , Péniguel C.
Published: July 2002

In many industrial applications, convection radiation and conduction participate simultaneously to the heat transfers. A numerical approach able to cope with such problems has been developed. The code SYRTHES is tackling conduction and radiation (limited to non participating medium). Radiation is solved by a radiosity approach, and conduction by a finite element method. Accurate and efficient algorithms based on a mixing of analytical/numerical integration, and ray tracing techniques are used to compute the view factors. The fluid part is solved by CFD codes like ESTET (Finite volumes) or N3S (Finite elements). SYRTHES relies on an explicit numerical scheme to couple all the phenomena. No stability problems have been encountered. To provide further flexibility, the three phenomena are solved on three independent grids. All data transfers being automatically taken care of by SYRTHES. Illustrating applications are shown.
The impacts of disaster exercises on participants
Authors: Peterson Danny M. , Perry Ronald W.
Published: July 2002

There is a prevailing assumption in the research literature that disaster exercises produce a wide variety of benefits that promote effective emergency management. Unfortunately, there are few studies available that confirm this assumption. This paper reviews the role of exercises in disaster management and places them within the context of preparedness activities. Within this context, the links among planning, training and exercising are explicated. The potential benefits of exercises are reviewed and hypotheses generated that link exercise experiences with emergency responders’ perceptions of planning adequacy, training adequacy, teamwork, response network effectiveness, equipment adequacy and job risk. The effects of two exercises – one dealing with hazardous materials and one with medical mass casualties – are examined using a quasi‐experimental research design. The subjects were professional firefighters. Results indicated that successful exercises can enhance perceptions of teamwork, training adequacy, response network effectiveness, job risk, and equipment adequacy. The link between exercise participation and perception of planning adequacy was found to be equivocal.
Inspection and policy making: some initial ideas
Authors: Lee John , Fitz John
Published: July 2002

Considers the role of Her Majesty′s Inspectorate (HMI) in the
maintenance, promotion and judgement of quality in schools. Drawing on
documentary evidence and interview data, briefly sets out the historical
context in which HMI operated and then focuses particularly on the role
of HMI from the 1970s until 1993. Argues that although the statutory
position of HMI as set out in The Rayner Report excludes them from
responsibility for quality directly, and gives them the duty of
reporting the health of the system to the Secretary of State, they
engaged in the policy making with respect to key aspects of quality i.e.
curriculum and pedagogy. Also argues that HMI are best seen as an
interpretive community, and it was this that enabled them to struggle
for the pedagogic device. Considers the arrangements for inspection
since 1993 and suggests that there is some concern about the quality
judgement of the new inspection process.
In‐house evaluation against the Investors in People standard: some pointers for self‐regulation in higher education
Authors: Daniel Michael J.
Published: July 2002

The national standard for staff development, “Investors in People”, is now being widely taken up in higher education. Institutional assessment takes place by individuals or small teams drawn from a network of accredited assessors. Ahead of formal assessment, institutions typically arrange a “mock assessment” using the same network of consultants. Describes the case where the mock assessment was brought in‐house using the experience of evaluation developed by an internal academic audit team. The team was able to produce an effective assessment which carried with it a range of benefits which could not have been achieved in such measure by an external process. The case shows the benefits of a flexible evaluative capacity in pressing for the case for a greater reliance in the future to be placed on self‐regulation, and points to a way in which more “owned” and cost effective approaches to investors’ assessments could be developed in the future.
Rejuvenating the IT supply organization
Authors: van der Zee Han. T.M.
Published: July 2002

Compelled by every increasing competition, newly opening markets, globalization, deregulation channels and joint ventures. Information technology (IT) is increasingly taking on a key role in this. IT helps in restructuring business units, business processes, business activities, and business networks, all with the aim of faster, cheaper and better performance. This means ever higher requirements are being set for the IT that is needed. Examines the necessary strategy and the questions that have to be answered by IT organization managers, if they are to be, and remain, successful.
Perceptions of the Internet: what people think when they search the Internet for information
Authors: Bruce Harry
Published: July 2002

The study described in this article aimed to gather insights into what people think when they search the Internet for information. The premise is that people relate to information services and systems metaphorically. In other words, they identify the system or service as analogous to something perhaps more mundane or commonplace. These are known as wild metaphors. They help to explain the unknown or unfamiliar and help us to learn new things. They arise from our individual beliefs and backgrounds but they are also inevitably influenced by our collective experience of contemporary media characterisations of the Internet. This study relates the analogies that academics in Australia report for the Internet with the satisfaction that they derive from information seeking on the network. It provides some insight into how academics in Australia perceive the Internet when they use it to search for information.
Strategic management spin‐offs of the Deming approach
Authors: Vinzant Janet C. , Vinzant Douglas H.
Published: July 2002

Many scholars have documented the importance of Deming’s legacy in the development of what is now commonly known as total quality management (TQM). Less often considered, however, is how Deming’s teachings have influenced other approaches to management. This article examines how Deming’s work has influenced the field of strategic management. It describes the history of strategic and quality management and highlights specific areas where Deming’s contributions have influenced and strengthened strategic management. It concludes with some comments about how Deming’s approach can be used to help organizations achieve both quality and strategic advantage.
Conformational propagation with prion‐like characteristics in a simple model of protein folding
Authors: Harrison Paul M. , Chan Hue Sun , Prusiner Stanley B. , Cohen Fred E.
Published: July 2002

Protein refolding/misfolding to an alternative form plays an aetiologic role in many diseases in humans, including Alzheimer's disease, the systemic amyloidoses, and the prion diseases. Here we have discovered that such refolding can occur readily for a simple lattice model of proteins in a propagatable manner without designing for any particular alternative native state. The model uses a simple contact energy function for interactions between residues and does not consider the peculiarities of polypeptide geometry. In this model, under conditions where the normal (N) native state is marginally stable or unstable, two chains refold from the N native state to an alternative multimeric energetic minimum comprising a single refolded conformation that can then propagate itself to other protein chains. The only requirement for efficient propagation is that a two‐faced mode of packing must be in the ground state as a dimer (a higher‐energy state for this packing leads to less efficient propagation). For random sequences, these ground‐state dimeric configurations tend to have more β‐sheet‐like extended structure than almost any other sort of dimeric ground‐state assembly. This implies that propagating states (such as for prions) are β‐sheet rich because the only likely propagating forms are β‐sheet rich. We examine the details of our simulations to see to what extent the observed properties of prion propagation can be predicted by a simple protein folding model. The formation of the alternative state in the present model shows several distinct features of amyloidogenesis and of prion propagation. For example, an analog of the phenomenon of conformationally distinct strains in prions is observed. We find a parallel between ‘glassy’ behavior in liquids and the formation of a propagatable state in proteins. This is the first report of simulation of conformational propagation using any heteropolymer model. The results imply that some (but not most) small protein sequences must maintain a sequence signal that resists refolding to propagatable alternative native states and that the ability to form such states is not limited to polypeptides (or reliant on regular hydrogen bonding per se) but can occur for other protein‐like heteropolymers.
Attribution of Tumour Lethality and Estimation of the time to Onset of Occult Tumours in the Absence of Cause-of-Death Information
Authors: Ahn Hongshik , Moon Hojin , Kodell Ralph L.
Published: July 2002

A new statistical approach is developed for estimating the carcinogenic potential of drugs and other chemical substances used by humans. Improved statistical methods are developed for rodent tumorigenicity assays that have interval sacrifices but not cause-of-death data. For such experiments, this paper proposes a nonparametric maximum likelihood estimation method for estimating the distributions of the time to onset of and the time to death from the tumour. The log-likelihood function is optimized using a constrained direct search procedure. Using the maximum likelihood estimators, the number of fatal tumours in an experiment can be imputed. By applying the procedure proposed to a real data set, the effect of calorie restriction is investigated. In this study, we found that calorie restriction delays the tumour onset time significantly for pituitary tumours. The present method can result in substantial economic savings by relieving the need for a case-by-case assignment of the cause of death or context of observation by pathologists. The ultimate goal of the method proposed is to use the imputed number of fatal tumours to modify Peto’s International Agency for Research on Cancer test for application to tumorigenicity assays that lack cause-of-death data.
Expectations Formation and Business Cycle Fluctuations: An Empirical Analysis of Actual and Expected Output in UK Manufacturing, 1975–1996
Authors: Lee Kevin , Shields Kalvinder
Published: July 2002

Direct measures of expectations, derived from survey data, are used in a Vector Autoregressive (VAR) model of actual and expected output in eight industries in the UK manufacturing sector. No evidence is found with which to reject rationality in the derived expectations series when measurement error is appropriately taken into account. The VAR analysis illustrates the importance of intersectoral interactions and business confidence in explaining the time profile of industrial outputs, examines the mechanisms by which shocks are propagated across sectors and over time and investigates the relative importance of sectoral and aggregate shocks of different types.
Forecast Bias and MSFE Encompassing
Authors: Marcellino Massimiliano
Published: July 2002

We show that the standard condition for MSFE encompassing is no longer valid when the forecasts to be compared are biased. We propose a simple modification of such a condition and of tests for its validity. The theoretical results are illustrated by an empirical example on inflation and deficit forecasts, key variables for the formulation of monetary and fiscal policy.
Membrane potential bistability is controlled by the hyperpolarization‐activated current IH in rat cerebellar Purkinje neurons in vitro
Authors: Williams Stephen R. , Christensen Soren R. , Stuart Greg J. , Häusser Michael
Published: July 2002

We investigated the role of the hyperpolarization‐activated mixed cation current, IH, in the control of spontaneous action potential firing of rat cerebellar Purkinje neurons in brain slices. Extracellular recordings revealed that the continual action potential firing of Purkinje neurons was disrupted by the pharmacological blockade of IH. Blockade of IH revealed spontaneous transitions between periods of tonic action potential firing and quiescence, without effects on the frequency or variance of action potential generation. Whole‐cell recordings revealed that blockade of IH unmasked a form of membrane potential bistability, where transitions between tonic firing and quiescent states (separated by ∼20 mV) were evoked by excitatory and inhibitory postsynaptic potentials, or by the delivery of brief (20 ms) somatic or dendritic positive and negative current pulses. The stable upper state of tonic action potential firing was maintained by the recruitment of axo‐somatic voltage‐activated sodium, but not calcium, channels. Negative modulation of IH by serotonin unmasked bistability, indicating that bistability of Purkinje neurons is likely to occur under physiological conditions. These data indicate that IH acts as a ‘safety net’, maintaining the membrane potential of Purkinje neurons within the range necessary for the generation of tonic action potential firing. Following the downregulation of IH, synaptic inhibition can generate long periods (seconds) of quiescence, the duration of which can be controlled by climbing fibre activation and by the underlying ‘tone’ of parallel fibre activity.
‘Sleepy’ inward rectifier channels in guinea‐pig cardiomyocytes are activated only during strong hyperpolarization
Authors: Liu Gong Xin , Daut Jürgen
Published: July 2002

K+ channels of isolated guinea‐pig cardiomyocytes were studied using the patch‐clamp technique. At transmembrane potentials between −120 and −220 mV we observed inward currents through an apparently novel channel. The novel channel was strongly rectifying, no outward currents could be recorded. Between −200 and −160 mV it had a slope conductance of 42.8 ± 3.0 pS (s.d.; n= 96). The open probability (Po) showed a sigmoid voltage dependence and reached a maximum of 0.93 at −200 mV, half‐maximal activation was approximately −150 mV. The voltage dependence of Po was not affected by application of 50 μm isoproterenol. The open‐time distribution could be described by a single exponential function, the mean open time ranged between 73.5 ms at −220 mV and 1.4 ms at −160 mV. At least two exponential components were required to fit the closed time distribution. Experiments with different external Na+, K+ and Cl− concentrations suggested that the novel channel is K+ selective. Extracellular Ba2+ ions gave rise to a voltage‐dependent reduction in Po by inducing long closed states; Cs+ markedly reduced mean open time at −200 mV. In cell‐attached recordings the novel channel frequently converted to a classical inward rectifier channel, and vice versa. This conversion was not voltage dependent. After excision of the patch, the novel channel always converted to a classical inward rectifier channel within 0–3 min. This conversion was not affected by intracellular Mg2+, phosphatidylinositol (4,5)‐bisphosphate or spermine. Taken together, our findings suggest that the novel K+ channel represents a different ‘mode’ of the classical inward rectifier channel in which opening occurs only at very negative potentials.
Darcy’s Experiments and the Deviation to Nonlinear Flow Regime
Authors: Lage J. L. , Antohe B. V.
Published: July 2002

Many important technological and natural processes involving flow through porous media are characterized by large filtration velocity. It is important to know when the transition from the linear flow regime to the quadratic flow regime actually occurs to obtain accurate models for these processes. By interpreting the quadratic extension of the original Darcy equation as a model of the macroscopic form drag, we suggest a physically consistent parameter to characterize the transition to quadratic flow regime in place of the Reynolds number, Re. We demonstrate that an additional data set obtained by Darcy, and so far ignored by the community, indeed supports the Darcy equation. Finally, we emphasize that the cubic extension proposed in the literature, proportional to Re3 and mathematically valid only for Re≪1, is irrelevant in practice. Hence, it should not be compared to the quadratic extension experimentally observed when Re⩾O1.[S0098-2202(00)01703-X]
Active Stabilization of Surge in an Axicentrifugal Turboshaft Engine
Authors: Nelson E. B. , Paduano J. D. , Epstein A. H.
Published: July 2002

Active stabilization of surge was implemented on an Allied Signal LTS-101 axicentrifugal gas producer, reducing the surging mass flow by 1 percent, for an operating range increase of 11 percent. Control was achieved using high-response sensors in the inlet and diffuser throat, coupled to actuators that injected air near the diffuser throat. System identification and modeling indicate that a classical surge-type eigenmode and an eigenmode associated with engine duct acoustics dominate the engine’s input–output properties. The surge eigenmode’s stability determines the open-loop surge mass flow. A robust linear controller with three inputs and one output stabilized this eigenmode without destabilizing the acoustic mode. The controller facilitated a 1 percent reduction in surging mass flow at 95 percent N1 corrected; this increases the engine’s choke to surge stable operating range by 11 percent. This paper elucidates the measured unsteady presurge behavior of the engine, and outlines a systematic procedure for surge control law development. [S0889-504X(00)01803-1]
Low-Order Models for Very Short Hybrid Gas Bearings
Authors: Savoulides N. , Breuer K. S. , Jacobson S. , Ehrich F. F.
Published: July 2002

A low-order model was created to analyze a small-scale gas bearing with a diameter of 4.1 mm, designed to spin at 2.4 million rpm. Due to microfabrication constraints, the bearing lies outside the standard operating space and stable operation is a challenge. The model is constructed by reference to Newton’s second law for the rotor and employs stiffness and damping coefficients predicted by other models. At any operating point it is able to predict (1) whether the journal can sustain stable operation, and (2) the whirling frequency of the journal. Analysis shows that the best way to operate the bearing is in a hybrid mode where the bearing relies on hydrostatics at low speeds and hydrodynamics at high speeds. However, in transitioning from hydrostatic to hydrodynamic operation, the model shows that the bearing is prone to instability problems and great care must be taken in scheduling the bearing pressurization system in the course of accelerating through low and intermediate rotational speeds.
Surveillance of Mechanical Systems on the Basis of Vibration Signature Analysis
Authors: Smyth A. W. , Masri S. F. , Caughey T. K. , Hunter N. F.
Published: July 2002

A comprehensive experimental study is presented to assess the utility of a proposed structural health monitoring and damage detection methodology based on vibration signature analysis of the test article. The approach uses a time-domain least-squares-based method to identify the reduced-order system matrices of an equivalent linear model whose order matches the number of available sensors. A quantification of the level of the system nonlinearity is obtained by determining the residual nonlinear forces involved in the system dynamics. The approach is applied to an intricate mechanical system about which virtually no information was available; i.e., the system was essentially a “black box.” By using similar measurements from a reference version of the test article and two subsequently modified versions, it is shown that through the use of higher-order statistics involving the probability density functions of key system parameters, a reliable measure of the extent of variation of the system influence functions may be obtained. The use of measures of the identified quantities’ dispersion offers a practical method for quantifying the reliability of the estimated changes involved in dealing with real-world (i.e., not noise-free) measurements that result in uncertain estimates of the physical changes in the article being monitored. [S0021-8936(00)03303-1]
On Torsion of Closed Thin-Wall Members With Arbitrary Stress-Strain Laws: A General Criterion for Cross Sections Exhibiting No Warping
Authors: Chiskis A. , Parnes R.
Published: July 2002

Warping due to torsion of closed thin-wall elastic members having constant thickness is investigated under the assumption of small strain but with arbitrary isotropic shear stress-strain laws. Based on a derived general criterion, it is shown that there exists a class of cross-sections which undergo no warping. For cases where warping exists, an example of simplified calculations, using the derived expressions, is presented for warping of a thin-wall rectangle. [S0021-8936(00)03503-0]
Simulations of Three-Dimensional Flow and Augmented Heat Transfer in a Symmetrically Grooved Channel
Authors: Greiner M. , Faulkner R. J. , Van V. T. , Tufo H. M. , Fischer P. F.
Published: July 2002

Navier-Stokes simulations of three-dimensional flow and augmented convection in a channel with symmetric, transverse grooves on two opposite walls were performed for 180⩽Re⩽1600 using the spectral element technique. A series of flow transitions was observed as the Reynolds number was increased, from steady two-dimensional flow, to traveling two and three-dimensional wave structures, and finally to three-dimensional mixing. Three-dimensional simulations exhibited good agreement with local and spatially averaged Nusselt number and friction factor measurements over the range 800⩽Re⩽1600. [S0022-1481(00)00904-X]
Discrete Frequency Models: A New Approach to Temporal Analysis
Authors: Adams Douglas E. , Allemang Randall J.
Published: July 2002

Forced vibration responses of nonlinear systems contain harmonics of the excitation frequency. These harmonics are either directly forced or are subharmonic, superharmonic, or combination resonances. Nonlinear responses of this type have been modeled historically using continuous time, discrete time, and continuous frequency models. A new approach to dynamic systems analysis is introduced here that uses difference equations in the discrete frequency domain to describe the evolution of forced, single degree of freedom, steady state vibration responses in frequency instead of time. A variety of possible applications in nonlinear experimental structural vibrations are also discussed.
Mechanism Design: Enumeration of Kinematic Structures According to Function
Authors: Tsai, Lung-Wen
Published: July 2002

[S1050-0472(00)03104-4]
Geometric Optimization of Periodic Flow and Heat Transfer in a Volume Cooled by Parallel Tubes
Authors: Rocha Luiz A. O. , Bejan Adrian
Published: July 2002

This paper addresses the fundamental problem of maximizing the thermal contact between an entire heat-generating volume and a pulsating stream of coolant that bathes the volume. The coolant flows through an array of round and equidistant tubes. Two laminar flow configurations are considered: stop-and-go flow, where the reservoir of coolant is on one side of the volume, and back-and-forth flow, where the volume is sandwiched between two reservoirs of coolant. The total heat transfer rate between the volume and the coolant is determined numerically for many geometric configurations in the pressure drop number range 102⩽B⩽106, and Pr⩾1. The optimal tube radius and the maximum volumetric heat transfer rate are determined numerically. The numerical optimization results are later predicted based on scale analysis by matching the longitudinal and transversal time scales of the temperature field in each tube, for each pulsation stroke. The predicted scales lead to power-law formulas that correlate the results and summarize the optimal geometry. The optimal tube size is nearly the same in stop-and-go flow and back-and-forth flow, and is independent of the pulsation frequency.
Predicting the Onset of a Low-Frequency, Limit-Cycle Type of Oscillatory Flow Instability in Multitube Condensing Flow Systems
Authors: Kobus C. J. , Wedekind G. L. , Bhatt B. L.
Published: July 2002

A means was developed for extending the predictive capability of the Equivalent Single-Tube Model (ESTM) to accurately predict the onset of a self-sustained oscillatory flow instability for a multitube condensing flow system. The model includes the effects of compressibility, subcooled liquid inertia, and thermal and flow distribution asymmetry. Previously, liquid inertia, a necessary mechanism for the instability, had not been modeled for a multitube system. Extensive experimental data was obtained for a two-tube system that verifies not only the predictive capability of the ESTM, but also its accuracy and its wide range of applicability.
Thermal Contact Resistance Modeling of Non-Flat, Roughened Surfaces With Non-Metallic Coatings
Authors: Marotta E. E. , Fletcher L. S. , Dietz Thomas A.
Published: July 2002

Essentially all models for prediction of thermal contact conductance or thermal contact resistance have assumed optically flat surfaces for simplification. A few thermal constriction models have been developed which incorporate uncoated, optically non-flat surfaces based on the bulk mechanical properties of the material. Investigations have also been conducted which incorporate the thermophysical properties of metallic coatings and their effective surface microhardness to predict the overall thermal contact conductance. However, these studies and subsequent models have also assumed optically flat surfaces; thus, the application of these models to optically non-flat, coated surface conditions is not feasible without modifications. The present investigation develops a thermomechanical model that combines both microscopic and macroscopic thermal resistances for non-flat, roughened, surfaces with non-metallic coatings. The thermomechanical model developed as a result of this study predicts the thermal contact resistance of several non-metallic coatings deposited on metallic aluminum substrates quite well.
Entropy Production as a Predictive Performance Measure for Turbomachinery
Authors: Paulus, D. M. , Gaggioli R. A. , Dunbar W. R.
Published: July 2002

It is proposed that consideration be given to an alternative, streamlined manner for mathematical modeling of the performance of energy conversion and transfer equipment. We make the case, here, by application to compressors. It is advocated that, instead of using an expression for efficiency as one of the governing equations, performance can be accounted for directly, with entropy production. It is shown that: (1) the modeling is more straightforward, using fewer relations, and (2) that compressor performance (e.g., maps) can be represented equally well.
An Improved Analytical Method for Life Prediction of Bolting
Authors: Ellis F. V. , Sielski D. R. , Viswanathan R.
Published: July 2002

A research project was conducted to develop and validate an improved, analytical life prediction method for high-temperature turbine and valve studs/bolts. The life prediction method used the two-parameter creep equation, an incremental calculation procedure and a strain hardening flow rule. The failure criterion was an accumulated inelastic or creep strain limit of 1 percent. The life prediction procedure recommends the use of the service history of operating temperature, number/stress level of tightenings, cycle time, etc., to calculate the stress relaxation behavior. Life assessment uses the measured bolt length to calculate the accumulated creep strain. The link between the current condition, i.e., accumulated creep strain, and the remaining creep life, i.e., time to accumulate 1 percent strain, is obtained by a prediction of the future creep strain accumulation under the intended loading cycle(s) imposed during future operation. In order to validate the approach, the calculated results were compared to the results of uniaxial stress relaxation testing, bolt model testing, and service experience. The analytical procedure coupled with other industry wide NDE and measurement procedures is expected to provide broad guidelines to utilities for bolting life assessment.
Diameter Effects on Nucleate Pool Boiling for a Vertical Tube
Authors: Kang Myeong-Gie
Published: July 2002

Diameter effects on nucleate pool boiling heat transfer for a tube with vertical orientation have been obtained experimentally. According to the results (1) the heat transfer coefficient decreases as the tube diameter increases and the trend is more notable with a rougher surface, and (2) the experimental data is in good agreement with the Cornwell and Houston’s correlation within a ±20 percent scatter range.
Aluminum Remelting using Directly Solar-Heated Rotary Kilns
Authors: Funken Karl-Heinz , Roeb Martin , Schwarzboezl Peter , Warnecke Heiko
Published: July 2002

To check the feasibility of solar thermal remelting of aluminum scrap a directly absorbing rotary kiln receiver-reactor was constructed for experimentation in a mini-plant scale in the DLR high flux solar furnace. Conventionally the high energy demand for heating rotary kilns is met by the combustion of fossil fuels. This procedure generates a big exhaust gas volume which is contaminated by volatiles if the technology is applied to treat waste materials. Application of concentrated solar radiation to provide the high temperature heat enables to substitute the fossil fuel. Thus smaller off-gas streams are generated and lower investment and O&M cost are expected for the off-gas purification. In this paper market and environmental issues are discussed and pre-designs both for solar pilot and industrial scale applications are presented.
A New Method for the Analysis of Deformation and Load in a Ball Bearing With Variable Contact Angle
Authors: Liao Neng Tung , Lin Jen Fin
Published: July 2002

The contact angle of a ball in a ball bearing is conventionally assumed to be a constant value in the mechanism analysis; in reality, this is not true. This assumption is made for the purpose of simplifying calculations, but the real elastic deformation produced at the position of each ball due to the acting force varying with the contact angle is unable to be considered. This study tries to establish a simple, three-dimensional expression for the elastic deformation at different position angles in terms of the geometry of the contact surface at the inner and outer races. Simply using the Newton method when the bearing deformations in the radial and axial directions are available can solve the contact angle as a function of position angle. Several characteristics arising from the variable contact angle will be discussed.
Engine Fuel Droplet High-Pressure Vaporization Modeling
Authors: Zhu G.-S. , Reitz R. D.
Published: July 2002

The objective of this investigation was to characterize the high-pressure vaporization processes of engine fuels, which are too complex in composition to be described with conventional methods. To do so a comprehensive model was developed for the transient vaporization process of droplets of practical engine fuels using continuous thermodynamics in which high-pressure effects are fully considered. Transport equations are derived in a spherical coordinate system for the semi-continuous systems of both gas and liquid phases. A general treatment of vapor-liquid equilibrium is presented, which can be applied with any type of cubic equation of state. Relations for the properties of the continuous species are formulated. The model is further applied to calculate the transient high-pressure vaporization processes of droplets of representative engine fuels—diesel and gasoline. The high-pressure vaporization processes of droplets of two single-component fuels are also predicted for comparison. The results clarify the characteristics of the vaporization processes of engine fuel droplets and indicate the significant effects of fuel type on the vaporization behavior. The comparison with the results of the single-component cases also emphasizes the importance of considering the influence of multicomponent fuels in practical applications.
Modal Analysis of Multi-Stepped Distributed-Parameter Rotor-Bearing Systems Using Exact Dynamic Elements
Authors: Hong Seong-Wook , Park Jong-Heuck
Published: July 2002

Although the exact dynamic elements have been suggested by the authors [1] and proved to be useful for the dynamic analysis of distributed-parameter rotor-bearing systems, difficulty remains in computation because of the presence of transcendental functions in the matrix. This paper proposes a complete analysis scheme for the exact dynamic elements, a generalized modal analysis method, to obtain exact and closed form solutions of time and frequency domain responses for multi-stepped distributed-parameter rotor-bearing systems. A numerical example is provided for validating the proposed method.
An Adaptive Statistically Based Controller for Through-Feed Centerless Grinding
Authors: Cowan Richard W. , Schertz Daniel J. , Kurfess Thomas R.
Published: July 2002

The purpose of this research is to develop a statistically based controller that is “self-tuning.” High volume manufacturing processes such as through-feed centerless grinding are best controlled with a statistical approach, but traditional methods of statistical control generally rely on fixed parameters that must be determined. These values must be precisely known and the true physical characteristics they model must remain constant throughout grinding, or traditional statistical control methods may break down. The mean and standard deviation of a process are measures of its accuracy and precision. The scheme developed here makes control decisions based on the real-time values of these quantities. This self-adjusting ability can compensate for changes in machine parameters as they occur.