bluuebunny/crossref_metadata_2025 huggingface dataset:
Semi-automatic protein crystallization system that allows in situ observation of X-ray diffraction from crystals in the drop
Authors: Watanabe Nobuhisa , Murai Hiroshi , Tanaka Isao
Published: September 2002

Semi-automatic protein crystallization device was developed using 96 format Hydra dispenser. Eight extra syringes were added for pipetting protein solution with its own dispensing mechanism. This device allows setting up 96 drops in about three minutes. New crystallization plate has also been developed. The plate allows collecting an oscillation photograph of the crystal directly in the drop. The diffraction quality of the crystals in the drops can be inspected without causing any other physical perturbations to the crystals. With the modified dispenser and this plate, we can perform both hanging and sitting drop vapour diffusion method.
Interest of the normalized second virial coefficient and interaction potentials for crystallizing large macromolecules
Authors: Bonneté F. , Vivarès D.
Published: September 2002

It has been shown for several years that the second virial coefficient, A2, can be helpfully used to describe the thermodynamic behavior of biological macromolecules in solution prior to crystallization. The coefficient, which reflects either repulsive or attractive interactions between particles, can allow a rapid determination of crystallization conditions. Different biological systems, from 14 kDa to 4600 kDa, were studied by small angle X-ray scattering. With large macromolecules, the A2 values were found at the low end of the crystallization slot described by George & Wilson [(1994) Acta Cryst. D50, 361-365]. This led us to investigate the physical meaning of the second virial coefficient and to propose the use of the dimensionless second virial coefficient independent of the molecular weight and the size of the particle, which only takes into account the interaction potential between macromolecules, to predict successful crystallization conditions for large macromolecules. With this normalized coefficient (a2), the effect of salt on small proteins becomes equivalent to the effect of PEG on large macromolecules in terms of interaction potentials.
Crystallization and structure analysis of Thermus flavus 5S rRNA helix B
Authors: Vallazza M. , Banumathi S. , Perbandt M. , Moore K. , DeLucas L. , Betzel C. , Erdmann V. A.
Published: September 2002

The crystallization conditions of the synthetic RNA duplex r(GCGGCGU)•r(GCGCCGC), part of the Thermus flavus 5S rRNA domain B, were investigated in detail. The crystallization analysis revealed a relativ narrow crystallization zone. Single sequence variations did not enhance the crystal quality, however the crystallization under microgravity provided crystals of higher quality. They belong to the space group P3121 with unit cell dimensions of a = b = 35.0 Å and c = 141.2 Å. Diffraction data up to 2.6 Å were collected and the structure subsequently analysed and refined to an R-value of 22.4 %. The conformation of the two molecules in the asymmetric unit is stabilized by intermolecular hydrogen bonds. The two molecules A and B are perpendicular to each other and interacting head to tail with symmetry related molecules. They form pseudo-continuous infinite helices in the crystal lattice.
Step bunching in a diffusion-controlled system: phase-shifting interferometry investigation of ferritin
Authors: Gliko Olga , Booth Nicholas A. , Vekilov Peter G.
Published: September 2002

We present a novel phase-shifting interferometry technique for investigations of the unsteady kinetics and the formation of spatio-temporal patterns during the protein crystallization. We applied this technique to the ferritin crystal growth, which is controlled by the rate of supply of material. We find strong fluctuations of growth rate, step density and step velocity due to passage of step bunches. The fluctuation amplitudes decrease with higher supersaturation and larger crystal size, as well as with increasing distance from the step sources. Since these are parameters affecting the solute supply field, we conclude that fluctuations are rooted in the coupling of the interfacial processes of growth to the bulk transport in the solution. Analysis of the step velocity dependence on local slope indicates a very weak interaction between the steps. Hence, in diffusion-controlled systems with non-interacting or weakly interacting steps the stable growth mode is that via equidistant step trains, and randomly arising step bunches decay.
The high-speed Hydra-Plus-One system for automated high-throughput protein crystallography
Authors: Krupka Heike I. , Rupp Bernhard , Segelke Brent W. , Lekin Tim P. , Wright David , Wu H.-C. , Todd Paul , Azarani Arezou
Published: September 2002

An automated high-throughput dispenser has been developed for the setup of protein crystallization trials by vapor diffusion or Microbatch methods. The Hydra®-Plus-One is composed of a Hydra®-PP system equipped with a motorized XYZ-platform, 96 precision glass syringes and a single-channel microsolenoid dispenser, which transfers 100nl-50μl of protein solution with an accuracy of > 90% at a speed of 60s per 96 wells. Up to 300μl of premixed cocktails can be aspirated with the 96-syringe-assembly and dispensed into reservoir and droplet wells within 60s. The Hydra®-Plus-One combines high precision, reliability and speed in a cost-effective high-throughput system ideally suited for protein crystallization
Two polymorphs of lysozyme nitrate: temperature dependence of their solubility
Authors: Legrand L. , Riès-Kautt M. , Robert M. C.
Published: September 2002

Two crystallographic forms of lysozyme nitrate are known, namely monoclinic and triclinic. Having previously determined the temperature dependence of the solubility of the monoclinic form (0.2 M NaNO3 solutions at pH = 4.5) [Legrand et al. (2001). J. Crystal Growth
232, 244-249], we focus here on the solubility of the triclinic form. The temperature dependence of the solubility of this crystallographic form has been measured with a static light device developed in our laboratory. This device allows to observe of the dissolution of one phase and/or the occurrence of a new one by varying the temperature with a sweep rate as low as 0.6 degree/hour. The new solubility data are complemented with crystallographic data of the triclinic form for the sake of completeness. The faces of a triclinic crystal are indexed. The crystallisation enthalpy of the triclinic form is deduced from these new results. These new solubility data allow us now to discuss (1) the publishedprotocols used to obtain the monoclinic and triclinic forms of lysozyme nitrate and (2) the phase transformation.
Nucleation rate determination by a concentration pulse technique: application on ferritin crystals to show the effect of surface treatment of a substrate
Authors: Tsekova Daniela , Popova Snejina , Nanev Christo
Published: September 2002

The nucleation of horse spleen ferritin (HSF) crystals on substrates was investigated using a new modification of the double pulse technique. The influence of three different structureless* substrates (glass, glass covered by methyl groups and poly-L-lysin template) on the nucleation was studied. The boundaries in the phase-diagram, which separate zones of crystal nucleation and growth were obtained by keeping pH = 5.0, and using CdSO4 as crystallizing agent. The steady-state nucleation rates were determined. The energy required for critical nuclei formation was evaluated (10-13 erg) and the sizes of critical nuclei were found (5 and 2 molecules).
Importance of the nature of anions in lysozyme crystallisation correlated with protein net charge variation
Authors: Retailleau Pascal , Ducruix Arnaud , Riès-Kautt Madeleine
Published: September 2002

Hofmeister anion series are studied to examine the coupled influence of pH and ionic strength on the solubility of previously desalted lysozyme. Solubility curves are measured at pH 4.3 and 8.3 and 18°C for nitrate, para-toluenesulfonate, citrate, sulphate, phosphate, and acetate. Extreme low ionic strength is explored, confirming the decrease of lysozyme solubility while increasing the protein net charge and the ionic strength. The classification of specific salt effects takes into account the valence of the anions with respect to the protein net charge.
Agarose as crystallisation media for proteins II: Trapping of gel fibres into the crystals
Authors: Gavira José Antonio , García-Ruiz Juan Manuel
Published: September 2002

The crystallisation pressure exerted by protein crystals growing in agarose gel does not disrupt the gel network. However, protein crystals trap agarose fibres when they grow in agarose gels. The fibres of agarose are distributed randomly in the crystals explaining why they do not appreciably affect the diffraction quality of the crystal
Conservation finance 2: area‐based initiatives and the role of foundations, funds and non‐profit agencies
Authors: Pickard Robert , Pickerill Tracy
Published: September 2002

This paper develops the issue of funding from a first paper “Conservation finance 1: support for historic buildings”), which highlighted specific measures in use including direct grant aid, low‐interest loans, fiscal relief, tax credits, the transference of development rights with associated funding measures and compensation schemes. Further consideration is given to other avenues for raising finance in support of the built heritage from public and also other sources as a part of the process of developing integrated conservation strategies (such as via foundations, lotteries, revolving funds and non‐profit organisations, combining methods of financing for individual properties including for housing rehabilitation and through area‐based schemes). Taken together, the two papers examine different approaches to funding the built heritage by reference to practice in western Europe and North America.
Commercial lease renewals – get a move on!
Authors: Swerling Leon
Published: September 2002

The Civil Procedure Rules that came into effect in October 2001 were intended to speed up litigation between landlords and tenants. This paper argues that they have had the opposite effect in that they have made the whole process of lease negotiation more onerous and complex. In a bid to enlighten commercial property practitioners, a practical guide though the chronological minefield of Part 2 of the Landlord and Tenant Act 1954 (“the Act”) and the CPR 1998 Part 56 is offered.
Internal relationship marketing: a key to enhanced supply chain relationships
Authors: Keller Scott B.
Published: September 2002

Competitive market pressures within today’s contemporary business environments have encouraged the partnership of many supply chain members. Of particular interest is the development of successful relationships between firms in an effort to gain product and service quality and efficiency that would otherwise go left unclaimed. This research specifically identifies the need for supply chain members to foster healthier relationships within the firm in order to realize more fully success and obtain the benefits associated with external partnerships. The concept of internal relationship marketing is employed and a model is proposed to aid companies in identifying the variables associated with marketing to the internal customer. The motor carrier industry provides an appropriate service setting for the analysis, and implications for retaining the very best customer‐conscious frontline employees are outlined.
Shipper‐carrier partnership issues, rankings and satisfaction
Authors: Gibson Brian J. , Rutner Stephen M. , Keller Scott B.
Published: September 2002

Over the past decade, there have been a number of studies that examined either shipper or carrier selection and evaluation factors. However, there has been little comparison between how these two groups perceive these factors with regard to their partners. This study examines the similarities and differences with the rankings of factors between shipper and carrier groups. Furthermore, the results highlight the various levels of satisfaction between the two groups.
Effective logistics outsourcing in New Zealand
Authors: Sankaran Jay , Mun David , Charman Zane
Published: September 2002

Reports an inductive, qualitative investigation into third party logistics contracts in New Zealand. The objective of the study was to uncover managerial insights into effective logistics outsourcing that are appropriate to the New Zealand context. A salient feature of the research is the methodology that involved going back‐and‐forth between data gathering (the principal source of data was flexible interviews) and analysis, which was conducted through formal coding techniques. Analysis reveals that the third party provider’s refraining from premature monetary commitments is an instrumental variable in the effectiveness of third party logistics contracts in New Zealand. Also uncovers how the uniqueness of the NZ context shapes third party logistics in NZ.
Gas Turbine Mach Number Control With Simplified Fuel System
Authors: Dadd G. J. , Chan K. K.
Published: September 2002

The compressor exit Mach number control theory presented here will enable improved control of transient compressor working point trajectories of a turbine engine. This will allow the steady working line to be raised towards the surge boundary with the advantage of increased thrust and reduced specific fuel consumption. This new control method can replace the rigid acceleration and deceleration limiters of the fuel control loop, and achieve superior surge avoidance performance. This paper documents the theoretical and practical study of Mach number controllers designed for implementation with a simplified fuel pump system and the subsequent testing of the controllers on an aeroengine in the sea level test bed in DERA Pyestock. The new controller incorporated two Mach number dynamic limiting control loops (one each for acceleration and deceleration) besides the NH controller. Several designs were tested successfully and demonstrated not only Mach number control from idle to full power, but also surge avoidance. Engine start control was also tested in the latest engine test.
Fuel Droplet Evaporation in a Supercritical Environment
Authors: Zhu G. S. , Aggarwal S. K.
Published: September 2002

This paper reports a numerical investigation of the transcritical droplet vaporization phenomena. The simulation is based on the time-dependent conservation equations for liquid and gas phases, pressure-dependent variable thermophysical properties, and a detailed treatment of liquid-vapor phase equilibrium at the droplet surface. The numerical solution of the two-phase equations employs an arbitrary Eulerian-Lagrangian, explicit-implicit method with a dynamically adaptive mesh. Three different equations of state (EOS), namely the Redlich-Kwong (RK), the Peng-Robinson (PR), and Soave-Redlich-Kwong (SRK) EOS, are employed to represent phase equilibrium at the droplet surface. In addition, two different methods are used to determine the liquid density. Results indicate that the predictions of RK-EOS are significantly different from those obtained by using the RK-EOS and SRK-EOS. For the phase-equilibrium of n-heptane-nitrogen system, the RK-EOS predicts higher liquid-phase solubility of nitrogen, higher fuel vapor concentration, lower critical-mixing-state temperature, and lower enthalpy of vaporization. As a consequence, it significantly overpredicts droplet vaporization rates, and underpredicts droplet lifetimes compared to those predicted by PR and SRK-EOS. In contrast, predictions using the PR-EOS and SRK-EOS show excellent agreement with each other and with experimental data over a wide range of conditions. A detailed investigation of the transcritical droplet vaporization phenomena indicates that at low to moderate ambient temperatures, the droplet lifetime first increases and then decreases as the ambient pressure is increased. At high ambient temperatures, however, the droplet lifetime decreases monotonically with pressure. This behavior is in accord with the reported experimental data.
Influence of Carbon Fabric on Fretting Wear Performance of Polyetherimide Composite
Authors: Bijwe Jayashree , Indumathi J. , Satapathy Bhabani K. , Ghosh Anup K.
Published: September 2002

A carbon fabric composite of Polyetherimide (PEI) was fabricated and studied for fretting wear behavior along with neat PEI. The operating parameters were load, temperature, amplitude and frequency of fretting. It was observed that carbon fabric proved to be significantly beneficial for reducing friction and wear of PEI. The friction coefficient of PEI was quite high and independent of operating parameters. For the carbon fabric composites (CFC) it reduced from 0.3 to 0.18 with an increase in load. On the other hand it showed marginal increase (0.18 to 0.28) with increase in temperature from 25°C to 200°C. The wear rate of the composite, CFC showed little variation with increase in load and temperature. Amplitude and frequency also proved to be important influencing parameters. Microscopic studies proved useful for understanding wear mechanism.
A Numerical Method for Analysis of Extended Rough Wavy Surfaces in Contact
Authors: Karpenko Yu. A. , Akay Adnan
Published: September 2002

Topographies of engineering surfaces normally have both random and periodic components, designated as surface roughness and waviness. True contacts between two such surfaces develop between the peaks, or asperities, on each surface. The waviness of the surfaces determines the spatial distribution of true contacts over the interface such that true contacts on wavy surfaces occur at and near the wave crests. This paper presents a computational method for analysis of contact between two rough wavy surfaces for which the nominal contact area may be arbitrarily large. The model used here combines local deflection of a contact point due only to the force acting on it with the non-local deflection of the same point due to forces at all other points of the surfaces. Using a three-stage loop similar to multi-level substructuring in finite element analysis and a nested iterative approach, the proposed method calculates the true contact area for a large number of asperity contacts, O103. Results of calculations show how contact parameters change with external load and also demonstrate the validity of the method.
Theoretical Modeling of Surface Asperity Depression Into an Elastic Foundation Under Static Loading
Authors: Radchik and V. S. , Ben-Nissan B. , Mu¨ller W. H.
Published: September 2002

A theoretical analysis is carried out in closed-form to quantitatively describe the pressing of an individual surface asperity into its elastic bulk when subjected to normal loads. To this end, a single asperity is simulated by a paraboloid of revolution of an arbitrary even power. The investigation is based on theory of elastic contact as originally developed by Shtaerman. It is shown that additional pressing of an individual asperity into the elastic bulk essentially depends upon four parameters: the elastic compression of its apex, the initial magnitude of the height of the asperity, a constant that characterizes the shape of the asperity peak, and the elastic properties of the materials involved in the contact. The analysis shows that the impression of the asperity into the elastic bulk increases for decreasing smoothness of the paraboloid. It will be demonstrated that the impression of the asperity into the elastic bulk, if both are made of the same material, typically reaches 50 percent of the value of elastic compression of the asperity peak.
A Review of Recent Approaches for Modeling Solid Third Bodies
Authors: Iordanoff I. , Berthier Y. , Descartes S. , Heshmat H.
Published: September 2002

The paper considers the behavior of third bodies in dry contacts. A description of the mechanism operating in contacts is given and the influence of external parameters outlined. Both physicochemical and mechanical conditions greatly influence third body behavior. Depending on third-body composition, the external influence can be more or less dramatic. Due to difficulties with experimentation, numerical modeling is suggested as a complementary tool. Two approaches for such modeling are described, the continuum and the discrete approach. At present these models are at an early development stage (two-dimensional simulations), and great efforts should be made for their further development. While an experimental apparatus can study phenomena at only one scale; namely the nanometer with AFM, or the micron to millimeter with fretting machines, modeling is able to range from the microscopic properties (particle interactions like coefficient of restitution) to the macroscopic properties by integration or averaging (load capacity, friction coefficient).
Numerical Techniques for Computing Rotordynamic Properties of Mechanical Gas Face Seals
Authors: Miller Brad A. , Green Itzhak
Published: September 2002

The gas film stiffness and damping properties for a spiral grooved mechanical face seal in a flexibly mounted stator configuration are computed using the step jump method and a novel direct numerical frequency response method. The seal model has three degrees of freedom, including axial displacement of the stator and two stator tilts about mutually perpendicular diametral axes. Results from both methods agree well with previously published results computed using the perturbation method, but the two new methods have the advantage of employing computer programs used in the direct numerical simulation of motion. Based on the linearized analysis, the two angular modes are proven to be coupled together and decoupled from the axial mode. Anomalies in the gas film properties tend to occur at large compressibility numbers. The step jump method requires less computing time than the direct frequency response method but at a sacrifice in accuracy at high excitation frequencies.
Laser Smoothing of the Load/Unload Tabs of Magnetic Recording Head Gimbal Assemblies
Authors: Singh Gurinder P. , Suk Mike , Albrecht and Thomas R. , Kozlovsky William T.
Published: September 2002

A novel technology to smooth the metal tab surfaces using a pulsed laser beam is applied to reduce the wear of the load/unload ramps used in disk drives that employ load/unload technology. The laser pulse length, pulse energy and the pulse repetition rate are so chosen that they cause the surface layer of the load/unload tab, approximately 2–3 um deep, to melt and refreeze quickly. As the surface layer melts, the surface tension of the melt removes most of the micro roughness and a smooth surface is obtained. The reduction in the micro surface roughness is confirmed by the AFM traces and a sharp decrease in the light scattered from the tab surface. In wear tests, such tabs show a remarkable improvement in the wear of the plastic load/unload ramps, allowing 5–10 × more load/unload cycles for a given amount of ramp wear.
Theoretical Investigation of Unsteady Squeeze Flow in a Curved Newtonian Squeeze Film
Authors: Usha and R. , Vimala P.
Published: September 2002

The laminar squeeze flow of a viscous incompressible fluid between a flat circular disk and an axisymmetric curved disk of arbitrary shape is investigated theoretically using modified lubrication theory. The characteristics of squeeze film are investigated through inertia and curvature effects on the normal force exerted on the upper curved moving disk described by an exponential function for the sinusoidal squeeze motion. The constant force squeezing state is also examined. It has been observed that the load carrying capacity of the curved squeeze film is strongly influenced by the curvature and inertia effects.
Data Rectification and Detection of Trend Shifts in Jet Engine Path Measurements Using Median Filters and Fuzzy Logic
Authors: Ganguli R.
Published: September 2002

Filtering methods are explored for removing noise from data while preserving sharp edges that many indicate a trend shift in gas turbine measurements. Linear filters are found to be have problems with removing noise while preserving features in the signal. The nonlinear hybrid median filter is found to accurately reproduce the root signal from noisy data. Simulated faulty data and fault-free gas path measurement data are passed through median filters and health residuals for the data set are created. The health residual is a scalar norm of the gas path measurement deltas and is used to partition the faulty engine from the healthy engine using fuzzy sets. The fuzzy detection system is developed and tested with noisy data and with filtered data. It is found from tests with simulated fault-free and faulty data that fuzzy trend shift detection based on filtered data is very accurate with no false alarms and negligible missed alarms.
Global Nonlinear Modeling of Gas Turbine Dynamics Using NARMAX Structures
Authors: Chiras N. , Evans C. , Rees D.
Published: September 2002

This paper examines the estimation of a global nonlinear gas turbine model using NARMAX techniques. Linear models estimated on small-signal data are first examined and the need for a global nonlinear model is established. A nonparametric analysis of the engine nonlinearity is then performed in the time and frequency domains. The information obtained from the linear modeling and nonlinear analysis is used to restrict the search space for nonlinear modeling. The nonlinear model is then validated using large-signal data and its superior performance illustrated by comparison with a linear model. This paper illustrates how periodic test signals, frequency domain analysis and identification techniques, and time-domain NARMAX modeling can be effectively combined to enhance the modeling of an aircraft gas turbine.
A Multiple Harmonic Open-Loop Controller for Hydro/Aerodynamic Force Measurements in Rotating Machinery Using Magnetic Bearings
Authors: Baun D. O. , Maslen E. H. , Knospe C. R. , Flack R. D.
Published: September 2002

Inherent in the construction of many experimental apparatus designed to measure the hydro/aerodynamic forces of rotating machinery are features that contribute undesirable parasitic forces to the measured or test forces. Typically, these parasitic forces are due to seals, drive couplings, and hydraulic and/or inertial unbalance. To obtain accurate and sensitive measurement of the hydro/aerodynamic forces in these situations, it is necessary to subtract the parasitic forces from the test forces. In general, both the test forces and the parasitic forces will be dependent on the system operating conditions including the specific motion of the rotor. Therefore, to properly remove the parasitic forces the vibration orbits and operating conditions must be the same in tests for determining the hydro/aerodynamic forces and tests for determining the parasitic forces. This, in turn, necessitates a means by which the test rotor’s motion can be accurately controlled to an arbitrarily defined trajectory. Here in, an interrupt-driven multiple harmonic open-loop controller was developed and implemented on a laboratory centrifugal pump rotor supported in magnetic bearings (active load cells) for this purpose. This allowed the simultaneous control of subharmonic, synchronous, and superharmonic rotor vibration frequencies with each frequency independently forced to some user defined orbital path. The open-loop controller was implemented on a standard PC using commercially available analog input and output cards. All analog input and output functions, transformation of the position signals from the time domain to the frequency domain, and transformation of the open-loop control signals from the frequency domain to the time domain were performed in an interrupt service routine. Rotor vibration was attenuated to the noise floor, vibration amplitude ≈0.2 μm, or forced to a user specified orbital trajectory. Between the whirl frequencies of 14 and 2 times running speed, the orbit semi-major and semi-minor axis magnitudes were controlled to within 0.5% of the requested axis magnitudes. The ellipse angles and amplitude phase angles of the imposed orbits were within 0.3 deg and 1.0 deg, respectively, of their requested counterparts.
Investigation of Two Advanced Cooling Mixing Concepts for a Rich Quench Lean Combustor
Authors: Diers O. , Koopman J. , Fischer M. , Hassa C.
Published: September 2002

To support the development of a rich quench lean pilot zone for a staged aeroengine combustor, two rectangular rich quench lean (RQL) combustor sectors have been investigated under atmospheric conditions. Two advanced cooling mixing concepts, effusion and impingement cooling, with one and two rows of secondary air inlet holes in the mixing zone, have been measured using intrusive and noninstrusive measurement techniques. The results elucidate the interrelations between the cooling concepts and the respective mixing and emissions performances. The measurements were accompanied by numerical calculations supporting the interpretations of the measured data. Drawbacks were observed for the near stoichiometric conditions of the effusion cooling concept near the wall, however, the quench zone design with two rows of staggered holes performs well. On the contrary, the impingement cooling system shows good results for the homogeneity of the primary zone, but since less quench air is available with impingement cooling, optimum mixing is more difficult to achieve.
The Ubiquitous Personal Turbine—A Power Vision for the 21st Century
Authors: McDonald C. F. , Rodgers C.
Published: September 2002

Having a personal computer (PC) and related electronic equipment in the majority of U.S. homes today is accepted without question. In the same vein, having a personal turbine (PT) in the home could also be taken for granted in coming decades to assure a constant and reliable source of electrical power, which is paramount in the e-business era. As addressed in this paper, gas turbine technology has advanced to the point where a natural gas-fired PT, rated at about 5 kW could reliably provide the total energy needs of an average home. The Industrial Revolution of the 18th century, in which a centralized factory replaced cottage industries, was made possible by introduction of the steam engine. In the 21st century IT Revolution, the situation will have essentially gone the full circle, with a high percentage of service industry work being done in the home. For individuals using the internet for conducting business a reliable source of electrical power is mandatory. Alas, this can no longer be assured by the U.S. power grid which is quickly reaching its capacity, and increasing outages will become more commonplace. One solution to this could be the use of PTs in homes in both cities and remote areas. Also it would be ideally suited to applications in the developing countries, where it could provide the total energy needs of villages and small communities. In this introductory paper it is projected that when mass produced in very large quantities like automobile turbochargers, the PT unit cost would be competitive.
A Unique Approach for Thermoeconomic Optimization of an Intercooled, Reheat, and Recuperated Gas Turbine for Cogeneration Applications
Authors: Bhargava R. , Peretto A.
Published: September 2002

In the present paper, a comprehensive methodology for the thermoeconomic performance optimization of an intercooled reheat (ICRH) gas turbine with recuperation for cogenerative applications has been presented covering a wide range of power-to-heat ratio values achievable. To show relative changes in the thermoeconomic performance for the recuperated ICRH gas turbine cycle, results for ICRH, recuperated Brayton and simple Brayton cycles are also included in the paper. For the three load cases investigated, the recuperated ICRH gas turbine cycle provides the highest values of electric efficiency and Energy Saving Index for the cogenerative systems requiring low thermal loads (high power-to-heat ratio) compared to the other cycles. Also, this study showed, in general, that the recuperated ICRH cycle permits wider power-to-heat ratio range compared to the other cycles and for different load cases examined, a beneficial thermodynamic characteristic for the cogeneration applications. Furthermore, this study clearly shows that implementation of the recuperated ICRH cycle in a cogeneration system will permit to design a gas turbine which has the high specific work capacity and high electric efficiency at low value of the overall cycle pressure ratio compared to the other cycles studied. Economic performance of the investigated gas turbine cycles have been found dependent on the power-to-heat ratio value and the selected cost structure (fuel cost, electric sale price, steam sale price, etc.), the results for a selected cost structure in the study are discussed in this paper.
Thermoeconomic Analysis of an Intercooled, Reheat, and Recuperated Gas Turbine for Cogeneration Applications—Part II: Part-Load Operation
Authors: Bhargava R. , Negri di Montenegro G. , Peretto A.
Published: September 2002

The knowledge of off-design performance for a given gas turbine system is critical particularly in applications where considerable operation at low load setting is required. This information allows designers to ensure safe operation of the system and determine in advance thermoeconomic penalty due to performance loss while operating under part-load conditions. In this paper, thermoeconomic analysis results for the intercooled reheat (ICRH) and recuperated gas turbine, at the part-load conditions in cogeneration applications, have been presented. Thermodynamically, a recuperated ICRH gas turbine-based cogeneration system showed lower penalty in terms of electric efficiency and Energy Saving Index over the entire part-load range in comparison to the other cycles (nonrecuperated ICRH, recuperated Brayton and simple Brayton cycles) investigated. Based on the comprehensive economic analysis for the assumed values of economic parameters, this study shows that a midsize (electric power capacity 20 MW) cogeneration system utilizing nonrecuperated ICRH cycle provides higher return on investment both at full-load and part-load conditions, compared to the other same size cycles, over the entire range of fuel cost, electric sale, and steam sale values examined. The plausible reasons for the observed trends in thermodynamic and economic performance parameters for four cycles and three sizes of cogeneration systems under full-load and part-load conditions have been presented in this paper.
Conformable Eddy-Current Sensors and Arrays for Fleetwide Gas Turbine Component Quality Assessment
Authors: Goldfine N. , Schlicker D. , Sheiretov Y. , Washabaugh A. , Zilberstein V. , Lovett T.
Published: September 2002

The conformable Meandering Winding Magnetometer (MWM®) eddy current sensors and MWM-arrays provide new inspection capabilities for gas turbine components. The sensors provide measurements of coating thickness and absolute electrical conductivity, which can capture features of interest for a population of components, e.g., for tracking fleetwide trends in quality and aging, failure evaluations, and correlating failure origins to features of specific fleet population segments. Inspection applications include metallic and nonmetallic coating thickness and porosity measurement, detection of cracks on complex surfaces, imaging and detection of small flaws, thermal degradation monitoring, and cold work quality assessment. For example, the U.S. Air Force uses the MWM for cold work quality control on all of the C-130 propeller blades that go through the Warner Robins ALC. For P-3 and C-130 propeller blades, trend analysis is being performed fleetwide. This paper describes MWM technology advances for absolute property measurements and specific capability demonstrations. Multifrequency quantitative inversion methods used for coating characterization are also used for characterization of process-affected zones, such as shot peen quality or titanium alpha case characterization.
Measurements Versus Predictions for the Dynamic Impedance of Annular Gas Seals—Part I: Test Facility and Apparatus
Authors: Dawson M. P. , Childs D. W. , Holt C. G. , Phillips S. G.
Published: September 2002

An experimental facility and apparatus are described for measuring the dynamic impedance and leakage characteristics of annular gas seals. The apparatus currently has a top speed of 29,800 rpm and can accommodate seal diameters up to 114.3 mm. The air-supply system can provide up to 13.79 MPa (2000 psi) of pressure at the seal inlet. Test seals are configured in a back-to-back arrangement inside the stator and air enters a central inlet annulus at two opposed radial positions. Labyrinth seals and bleed ports located outboard of each test seal are used to control the pressure drop across the test seals. Two orthogonal, external hydraulic shakers are used to excite the test stator at frequencies up to 400 Hz. At a given operating condition, the apparatus can measure the rotordynamic impedance of a pair of identical seals over a broad frequency range using a single pseudo-random excitation waveform. Measurements are also made of seal leakage rates and upstream and downstream temperatures and pressures.
Estimation of Distributed Unbalance of Rotors
Authors: Yang T. , Lin C.
Published: September 2002

Mass unbalance commonly causes vibration of rotor-bearing systems. Lumped mass modeling of unbalance was adapted in most previous research. The lumped unbalance assumption is adequate for thin disks or impellers, but not for thick disks or shafts. Lee et al. (Lee, A. C., et al., 1993, “The Analysis of Linear Rotor-Bearing Systems: A General Transfer Matrix Method,” ASME J. Vib. Acoust., 115, pp. 490–497) proposed that the unbalance of shafts should be continuously distributed. Balancing methods based on discrete unbalance models may not be very appropriate for rotors with distributed unbalance. A better alternative is to identify the distributed unbalance of shafts before balancing. In this study, the eccentricity distribution of the shaft is assumed in piecewise polynomials. A finite element model for the distributed unbalance is provided. Singular value decomposition is used to identify the eccentricity curves of the rotor. Numerical validation of this method is presented and examples are given to show the effectiveness of the identification method.
A Database for Couette Flow Rate Considering the Effects of Non-Symmetric Molecular Interactions
Authors: Li Wang-Long
Published: September 2002

A complete database for Couette flow rate (QCD,α1,α2,0.1⩽α1,α2⩽1.0,0.01⩽D⩽100, where D=inverse Knudsen number) for ultra-thin gas film lubrication problems is advanced. When the accommodation coefficients (AC) of the two lubricating surfaces are different α1≠α2, the Couette flow rate in the modified molecular gas film lubrication (MMGL) equation should be corrected. The linearized Boltzmann equation (under small Mach number conditions) is solved numerically for the case of non-symmetric molecular interactions α1≠α2. The Couette flow rate is then calculated, and the database is constructed. The present database can be easily implemented in the MMGL equation. In addition, the present database extends the previously published results for 0.1⩽α1,α2⩽0.7. The database for low ACs is valuable in the analysis and applications of MEMS devices (bushings of electrostatic micro motors, micro bearings, magnetic head/disk interfaces, etc.), and their future development.
An Average Lubrication Equation for Thin Film Grain Flow With Surface Roughness Effects
Authors: Tsai Hung-Jung , Jeng Yeau-Ren
Published: September 2002

A closed-form average lubrication equation for thin film grain flow with the effects of surface roughness is derived. This equation is based on Haff’s grain flow theory and also the flow factors proposed by Patir and Cheng. The flow factors, derived by the perturbation approach and coordinate transformation, are expressed in terms of surface characteristics (three characteristics for each surface: roughness orientation, Peklenik number and standard derivation) and particle size. Finally, the flow factors under different surface characteristics and particle size are discussed.
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Formation in High-Pressure Jet-Stirred Reactors With Significance to Lean-Premixed Combustion Turbines
Authors: Rutar T. , Malte P. C.
Published: September 2002

Measurements of NOx and CO in methane-fired, lean-premixed, high-pressure jet-stirred reactors (HP-JSRs), independently obtained by two researchers, are well predicted assuming simple chemical reactor models and the GRI 3.0 chemical kinetic mechanism. The single-jet HP-JSR is well modeled for NOx and CO assuming a single PSR for Damko¨hler number below 0.15. Under these conditions, the estimates of flame thickness indicate the flame zone, that is, the region of rapid oxidation and large concentrations of free radicals, fully fills the HP-JSR. For Damko¨hler number above 0.15, that is, for longer residence times, the NOx and CO are well modeled assuming two perfectly stirred reactors (PSRs) in series, representing a small flame zone followed by a large post-flame zone. The multijet HP-JSR is well modeled assuming a large PSR (over 88% of the reactor volume) followed by a short PFR, which accounts for the exit region of the HP-JSR and the short section of exhaust prior to the sampling point. The Damko¨hler number is estimated between 0.01 and 0.03. Our modeling shows the NOx formation pathway contributions. Although all pathways, including Zeldovich (under the influence of super-equilibrium O-atom), nitrous oxide, Fenimore prompt, and NNH, contribute to the total NOx predicted, of special note are the following findings: (1) NOx formed by the nitrous oxide pathway is significant throughout the conditions studied; and (2) NOx formed by the Fenimore prompt pathway is significant when the fuel-air equivalence ratio is greater than about 0.7 (as might occur in a piloted lean-premixed combustor) or when the residence time of the flame zone is very short. The latter effect is a consequence of the short lifetime of the CH radical in flames.
Performance Analysis of Evaporative Biomass Air Turbine Cycle With Gasification for Topping Combustion
Authors: Wolf J. , Barone F. , Yan J.
Published: September 2002

This paper investigates the performance of a new power cycle, a so called evaporative biomass air turbine (EvGT-BAT) cycle with gasification for topping combustion. The process integrates an externally fired gas turbine (EFGT), an evaporative gas turbine (EvGT), and biomass gasification. Through such integration, the system may provide the potential for adapting features from different advanced solid-fuel-based power generation technologies, e.g., externally fired gas turbine, integrated gasification combined cycle (IGCC), and fluidized bed combustion, thus improving the system performance and reducing the technical difficulties. In the paper, the features of the EvGT-BAT cycle have been addressed. The thermal efficiencies for different integrations of the gasification for topping combustion and the heat recovery have been analyzed. By drying the biomass feedstock, the thermal efficiency of the EvGT-BAT cycle can be increased by more than three percentage points. The impact of the outlet air temperature of the high-temperature heat exchanger has also been studied in the present system. Finally, the size of the gasifier for topping combustion has been compared with the one in IGCC, which illustrates that the gasifier of the studied system can be much smaller compared to IGCC. The results of the study will be useful for the future engineering development of advanced solid fuel power generation technologies.
Plastic Deformation of a Perforated Sheet With Nonuniform Circular Holes Along the Thickness Direction
Authors: Chen Fuh-Kuo , Lee Yi-Che
Published: October 2002

For a perforated sheet with circular holes, used in shadow masks, the diameter of the circular hole varies through the thickness, and the nonuniform circular holes are arranged in a triangular pattern. In order to simplify the analysis, a perforated sheet with equivalent circular holes of uniform diameter is proposed such that its plastic behavior is similar to that with the given nonuniform circular holes. In this study, a yield criterion is discussed for the perforated sheet with uniform circular holes by employing an equivalent continuum approach, which is then applied to examine the plastic deformation of the perforated sheet with nonuniform circular holes. The analytical results predicted by the theory, including those for the apparent yield stresses and strain ratios, are verified by the results obtained from the finite element analysis and also from experiments.
Development of Shape Memory TiNi Fiber Reinforced Epoxy Matrix Composite and Its Properties
Authors: Shimamoto Akira , Hawong Jai-Sug , Lee Hyo-Jae
Published: October 2002

Shape memory alloy TiNi fiber epoxy resin composite (SMA-FEC) was developed and the active reinforcement effect of the material was investigated by strain gauge measurement and photoelastic method. In this paper material processing of the SMA-FEC and mechanical testing results are described. The recovery stress-strain at various ambient temperatures by means of strain gauges are reported. A typical shrinkage of the SMA-FEC was recognized with increasing temperature above the inverse transformation temperature Af of embedded SMA TiNi fiber, and it depended on the fiber volume fraction Vf as well as prestrain value. The validity of the composite using the photoelastic model was discussed in detail. By adjusting the fiber volume fraction and prestrain, one can obtain expected elastic modulus and stress fringes value to conduct photoelastic experiment with SMA-FEC as model material. The active reinforcement of the SMA-FEC smart composite was reconfirmed visually from the change of the photoelastic fringe patterns of the specimen by heating at various temperatures.
An Improvement of Multiaxial Ratchetting Modeling Via Yield Surface Distortion
Authors: Vincent Ludovic , Calloch Sylvain , Kurtyka Tadeusz , Marquis Didier
Published: October 2002

Many theoretical studies have been made to describe multiaxial ratchetting and most of them have been concentrated on the location of the yield domain, not on its shape. In this paper, we introduce nonlinear kinematic constitutive equations consistent with ratchetting modeling into the distortional model of subsequent yield surfaces proposed by Kurtyka, T., and Zyczkowski, M. We use an efficient polycrystalline model to simulate complex tests including yield surface detections in order to get some reference predictions to use in the development of the constitutive laws introduced into the distortional model. The distortional model is thus qualitatively identified with the polycrystalline model and then quantitatively identified with the experimental results on a type 316L stainless steel. It gives promising results.