bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the Transfer Function for Measuring Ultrasonic Wave Speed in Engineering Materials
Authors: Leisk Gary G. , Saigal Anil , Pereira J. M.
Published: February 2015

Ultrasonic testing is used in determining mechanical properties such as modulus of elasticity, shear modulus, and Poisson’s ratio, in characterizing microstructures, and in detecting flaws. One application of ultrasound, known as acoustoelasticity, involves the measurement of ultrasonic wave speed in solid materials as a function of applied stress. Due to the high resolution that is required, a type of phase-slope analysis technique known as the transfer function technique is introduced as an alternative to the popular cross-correlation technique for measuring ultrasonic wave speed. Time delay results from software-simulated sinusoidal waveforms and measurements of the acoustoelastic response of aluminum 6061-T6 and stainless steel show that significant improvement in resolution and reduction in calculation time can be achieved by using the transfer function technique.
Development of a Controlled-Expansion Superalloy for Use in Aircraft Gas Turbines
Authors: Dahl James M. , Hansen John B.
Published: February 2015

This paper describes the methodology employed to produce a controlled expansion superalloy that has been successfully incorporated in several advanced aircraft gas turbine engines. Objectives of the original R&D study are reviewed in light of requirements given by potential customers. Properties of the alloy are presented and compared to those objectives. It is reported that the alloy has mechanical properties similar to those of the nickel-base alloy 718, and a low coefficient of thermal expansion between room temperature and its Curie temperature of 320°C. It also reported that the alloy has sufficient oxidation resistance so it may be possible to use it uncoated to temperatures approaching 675°C. The selection of the alloy by engine producers is described and the reasons for selecting are noted to be different from the original design criteria.
Description of a Vibration Diagnostic Trending Approach for a Condition Monitoring System for the LM2500 Gas Turbine
Authors: Hartranft John J.
Published: February 2015

In a gas turbine marine propulsion installation, especially a military type role, the design of an effective gas turbine vibration diagnostic system must provide both technical information for maintenance and operational risk assessment for continued engine operation. In order to fulfill these criteria, a vibration monitoring system must provide not only a feedback of measured vibration levels, it must also provide an interpretation of those levels. This paper describes a potential approach to trending LM2500 gas turbine generated vibration data for use in a condition monitoring system.
A Numerical Model of the Onset of Stall Flutter in Cascades
Authors: Clark William S. , Hall Kenneth C.
Published: February 2015

In this paper, we present a computational fluid dynamic model of the unsteady flow associated with the onset of stall flutter in turbomachinery cascades. The unsteady flow is modeled using the laminar Navier-Stokes equations. We assume that the unsteadiness in the flow is a small harmonic disturbance about the mean or steady flow. Therefore, the unsteady flow is governed by a small-disturbance form of the Navier-Stokes equations. These linear variable coefficient equations are discretized on a deforming computational grid and solved efficiently using a multiple-grid Lax-Wendroff scheme. A number of numerical examples are presented which demonstrate the destabilizing influence of viscosity on the aeroelastic stability of airfoils in cascade, especially for torsional modes of blade vibration.
Design and Experimental Investigation of a Mixed Flow Supersonic Compressor Stage
Authors: Elmendorf Wolfgang , Kurz Harald , Gallus Heinz E.
Published: February 2015

Highly loaded transonic and supersonic compressors appear capable of meeting the future demands of small gas turbines and jet engines. Particularly mixed flow compressors, taking advantage of the increasing circumferential blade speed between rotor inlet and exit, represent a good compromise with regard to high pressure ratio and mass flow on the one hand, and favorable performance characteristics and efficiency on the other.

However, operating a supersonic rotor as part of a stage involves a stator characterized by high turning angles, supersonic inlet conditions and a strong flow deceleration. In fact, the stator can be identified as the critical component regarding overall stage performance. Based on experimentally determined rotor exit flow conditions, the first part of this paper describes the design of a tandem stator with a strong shock in the stator entrance region, followed by subsonic flow turning and diffusion.

The main thrust of this paper is to present the analytical results obtained in connection with the experimental investigation of the complete stage at design and off-design conditions. Rotor and stator flow as well as the overall stage performance are discussed in detail. The concept of the tandem stator proves to be suitable for managing the extremely high aerodynamic loading in the Stator. Experimental results reveal the design goals to be met in general.
Observations of Wake-Induced Transition on an Axial Compressor Blade
Authors: Solomon W. J. , Walker G. J.
Published: February 2015

A closely-spaced array of hot-film gages fully covering both suction and pressure surfaces on the outlet stator of a 1.5-stage axial compressor was used to obtain dynamic measurements of wall shear stress. Observations were made over a range of Reynolds numbers at an incidence close to the design value. Various methods of presnting the data, including time-space contour plots of ensemble-average intermittency from the film gages are analyzed: related problems of interpretation are discussed. Extensive regions of laminar flow were identified on the suction surface: at the highest Reynolds number, small laminar patches were still evident at 85% chord and transitional flow covered up to 70% of suction surface length. The influence of passing rotor wakes on transition varied markedly with Reynolds number. The behavior of wake-induced transitional strips on the suction and pressure surfaces of the compressor blade differed significantly; their propagation characteristics also varied in some respects from those observed on turbine airfoils.
Ceramic Stationary Gas Turbine Development Program: Design and Life Assessment of Ceramic Components
Authors: Norton Paul F. , Frey Gary A. , Bagheri Hamid , Flerstein Aaron , Twardochleb Chris , Jimenez Oscar , Saith Arun
Published: February 2015

A program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts.

It is envisioned that the successful demonstration of ceramic gas turbine technology, and the systematic incorporation of ceramics in existing and future gas turbines will enable more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions.

The engine selected for the program, the Centaur 50 (formerly named Centaur ‘H’) will be retrofitted with first stage ceramic blades, first stage ceramic nozzles, and a ceramic combustor liner. The engine hot section is being redesigned to adapt the ceramic parts to the existing metallic support structure.

The program currently in Phase II focuses on detailed engine and component design, ceramic component fabrication, ceramic component testing, establishment of a long term materials property database, and the development and application of supporting technologies in the areas of life prediction and non-destructive evaluation. This paper outlines the design activities associated with the introduction of a ceramic first stage nozzle and two configurations of ceramic first stage turbine blade. In addition, probabilistic life assessment of the ceramic parts for major failure modes (fast fracture, slow crack growth and where relevant, creep and oxidation) will be discussed.
Phosphor Thermometry of Gas Turbine Surfaces
Authors: Allison Stephen W. , Beshears David L. , Cates Michael R. , Noel Bruce W. , Turley W. D.
Published: February 2015

This paper describes a nondestructive method for thermometry applicable to ceramic surfaces and coatings. To date our primary application has been to turbine engine and air vehicle surfaces. This method makes use of thermally sensitive phosphors many of which, as it turns out, are also ceramics. These materials fluoresce when suitably illuminated by ultraviolet light. The fluorescence intensity and decay time are well-behaved functions of temperature and therefore serve as reliable indicators of the temperature of the substrate to which the fluorescing material is attached. It is a non-contact method in that the light delivery and collection optics can be remotely located. A range of phosphor materials have been tested and any temperature ranging from 8 to 1900 K can be measured by selection of the appropriate phosphor. Turbine blades, vanes, thermal barrier coatings, and panels are examples of surfaces which have been diagnosed to date in either engine or engine-simulation facilities. A variety of coating methods are used, including electron-beam deposition, radio-frequency sputtering, and curing with inorganic binders. This paper summarizes the results to date and status of this technology.
Predictions of Tensile Behavior and Strengths of a Si3N4 Ceramic at High Temperatures Based on a Viscoplastic Model
Authors: Liu Kenneth C. , Brinkman Charles R. , Ding Jow-Lian , Lin Shengbin
Published: February 2015

Tensile deformation and rupture behavior were simulated using a viscoplastic model developed recently. The model was formulated based on the state variable approach, which provides flexibility and versatility for characterizing the time-dependent behavior of ceramic materials under general thermomechanical loading conditions. Simulations portrayed by the model were compared with experimental tensile data obtained under two different tensile stressing rates. Results showed that the model was capable of simulating deformation behavior for all practical engineering purposes, but estimated high-temperature fracture strengths somewhat conservatively.
Strength Prediction of Ceramic Components Under Complex Stress States
Authors: Peralta A. D. , Wu D. C. , Brehm P. J. , Cuccio J. C. , Menon M. N.
Published: February 2015

The capability to perform accurate fast-fracture strength predictions for ceramic components under complex stress states must be available in order to transition the use of advanced, high-strength ceramic materials from the laboratory to the high-strength/high-temperature applications they are intended for. Multiaxial strength prediction theories have provided the prediction capabilities, but only limited testing of these theories under complex states of stress and stress gradient conditions has been performed previously. Presented here are comprehensive test results and strength predictions for ceramic components subjected to complex states of stress and stress gradient conditions. The results show excellent agreement of the predictions from the multiaxial theories with test results for volumetrically-distributed flaws. An important finding of this work is the problem that arises in performing component surface strength predictions from database-type specimens. Database-type specimens and component surface properties are not necessary correlated, and in many cases it may be completely inaccurate to use database-type specimen surface properties for component surface strength predictions.
Throughflow Method for Turbomachines Applicable for All Flow Regimes
Authors: Damle S. V. , Dang T. Q. , Reddy D. R.
Published: February 2015

A new axisymmetric throughflow method for analyzing and designing turbomachines is proposed. This method utilizes body-force terms to represent blade forces and viscous losses. The resulting equations of motion, which include these body-force terms, are casted in terms of conservative variables and are solved using a finite-volume time-stepping scheme. In the inverse mode, the swirl schedule in the bladed regions (i.e. the radius times the tangential velocity rVθ) is the primary specified flow quantity, and the corresponding blade shape is sought after. In the analysis mode, the blade geometry is specified and the flow solution is computed. The advantages of this throughflow method compared to the current family of streamline curvature and matrix methods are that the same code can be used for subsonic/transonic/supersonic throughflow velocities, and the proposed method has a shock capturing capability. This method is demonstrated for designing a supersonic throughflow fan stage and a transonic throughflow turbine stage.
Parametric Modelling of Exhaust Gas Emission From Natural Gas Fired Gas Turbines
Authors: Bakken L. E. , Skogly L.
Published: February 2015

Increased focus on air pollution from gas turbines in the Norwegian sector of the North Sea has resulted in taxes on CO2. Statements made by the Norwegian authorities imply regulations and/or taxes on NOx emissions in the near future. The existing CO2-tax of NOK 0.82 /Sm3 (US Dollars 0.12/Sm3) and possible future tax on NOx are analysed mainly with respect to operating and maintenance costs for the gas turbine. Depending on actual tax levels, the machine should preferably be operated on full load/optimum thermal efficiency or part load to reduce specific exhaust emissions.

Based on field measurements, exhaust emissions (CO2, CO, NOx, N2O, UHC etc.) are established with respect to load and gas turbine performance, including performance degradation. Different NOx emission correlations are analysed based on test results, and a proposed prediction model presented. The impact of machinery performance degradation on emission levels is particularly analysed. Good agreement is achieved between measured and predicted NOx emissions from the proposed correlation.

To achieve continuous exhaust emission control, the proposed NOx model is implemented to the on-line condition monitoring system on the Sleipner A platform, rather than introducing sensitive emission sensors in the exhaust gas stack. The on-line condition monitoring system forms an important tool in detecting machinery condition/degradation, air pollution and achieving optimum energy conservation.
A Conceptual Design Methodology for Predicting Bleed and Horsepower Requirements of Military Aircraft Engines
Authors: Cyrus John D.
Published: February 2015

Conceptual design codes have been developed lo provide conceptual design estimates of bleed and horsepower extraction requirements of advanced military aircraft. This paper describes the methodology for the computer codes. The validity of the models was assessed by generating bleed and horsepower estimates for four advanced aircraft configurations not included in the data base and comparing the models estimates to manufacturer’s estimates.
Nondestructive Characterization of Ceramic Composites Used as Combustor Liners in Advanced Gas Turbines
Authors: Ellingson W. A. , Rothermel S. A. , Simpson J. F.
Published: February 2015

Nondestructive characterization (NDC) methods which can provide full field information about components prior to and during use are critical to the reliable application of continuous fiber ceramic matrix composites in high firing temperature (>1350°C) gas turbines. For combustor liner applications, although nonmechanical load bearing components, thermal characteristics as well as mechanical integrity is vitally important. NDC methods being developed to provide necessary information include x-ray computed tomography (mainly for through-wall density and delamination detection), infrared-based thermal diffusivity imaging, and single-wall through-transmission x-ray imaging (mainly for fiber content and alignment detection). Correlation of the data obtained from NDC methods with subscale combustor liner tests have shown positive results at thermal cycling temperatures from 700°C to 1177°C.
Trends in the Design and Analysis of Components Fabricated From CFCCs
Authors: Duffy S. F. , Palko J. L. , Sandifer J. B. , DeBellis C. L. , Edwards M. J. , Hindman D. L.
Published: February 2015

Continuous fiber ceramic composite materials (CFCCs) are being considered for an increasing number of commercial applications. They provide the potential for lighter, stranger, more corrosion resistant components that can perform at higher temperature for long periods of time. Global competitiveness demands a shortening of the time for CFCC commercialization. Thus considerable effort has been expended to develop and improve the materials, and to a lesser extent, to develop component design methods and data bases of engineering properties. To shorten the time to commercialization, project efforts must be integrated, while balancing project resources between material development and engineering design. Currently a good balance does not exist for most materials development projects. To rectify this imbalance, improvements in engineering design and development technologies must be supported and accelerated, with a focus on component issues. This will require project managers to give increasing emphasis to component design needs in addition to their current focus on material development.
Development of a High-Speed, High-Efficiency Power Turbine for the LM2500+
Authors: Benvenuti Erio , Casper Russ
Published: February 2015

The LM2500+ is the growth version of General Electric’s LM2500 aero-derivative gas turbine of which there are over 1,300 units delivered for service in marine propulsion, electric power generation and mechanical drive applications. Design rated for 29 MW (39,000 shp), the LM2500+ will be available with a High Speed Power Turbine (HSPT) for both mechanical drive and electrical power generation applications. This HSPT is being designed and developed by Nuovo Pignone in a coordinated effort with GE’s LM2500+ design program. This paper will outline the HSPT project background, the conceptual layout and the aerodynamic design aspects deemed as the most relevant in determining the expected performance for both mechanical drive and power generation applications.
Rotational Effects on Heat Transfer at Advanced Engine Conditions
Authors: Staub F. W. , Maddaus A. D. , Tekriwal P. K.
Published: February 2015

Cooling of Gas turbine buckets to ensure adequate life margin with coolants at advanced engine conditions of pressure and temperature requires that the internal heat transfer as influenced by rotation be known with sufficient accuracy. The existing data base, comprised of information readily available in the open literature has limited advanced design applicability considering the range of geometric and fluid-thermal dimensionless parameters of interest. Further, studies conducted with the aid of computational fluid dynamics (CFD) have demonstrated that, as the range of such parameters is extended, the characteristics of the predicted heat transfer capability change significantly, to the extent that bucket coolant passage designs that are fully acceptable at state-of-the-art conditions are marginal or unacceptable at advanced conditions. The purpose of this paper is threefold, to: a) demonstrate the need for extending the current internal heat transfer data base, accounting for the effects of rotation, b) provide a physical understanding of the expected heat transfer characteristics at advanced conditions, and c) describe a test rig and test program focused on obtaining the data of interest.
A Test Rig for the Identification of Rotordynamic Coefficients of Fluid Film Bearing Elements
Authors: Robison L. Miller , Arauz Grigory , San Andres Luis
Published: February 2015

A test rig and measurement procedure to identify the rotordynamic coefficients of generic fluid film bearing elements are described. The test apparatus allows the exchange of test articles without modifications to the basic design of the machine. The maximum operating speed of the rig is 9,000 rpm, with static loads to 4,450 N (1,000 lb) and available fluid supply pressures to 689 kPa (100 psi). Impact load excitations in two orthogonal directions bring the test bearing into dynamic motion, and a data acquisition and computer system record the dynamic response at a frequency of 12,000 samples per second.

Test bearing elements undergo multiple forced dynamic tests, and the corresponding time responses are transformed into the frequency domain and averaged. Bearing stiffness, damping, and inertia force coefficients are then identified from an impedance matrix in the frequency domain. Dynamic tests for an open ends squeeze film damper at various journal center static (offset) positions are presented for three levels of impact loads. In general, the identified damping coefficients correlate well with theoretical predictions.
A New Method for the Prediction of Compressor Performance Maps Using One-Dimensional Row-by-Row Analysis
Authors: Attia Magdy S. , Schobeiri M. Taher
Published: February 2015

This article presents a new and simple method for the prediction of the compressor performance maps based on the geometry and the design point data. The method accurately calculates the compressor performance map based on a comprehensive one-dimensional row-by-row analysis. Off-design efficiency is determined using a modified diffusion factor and an advanced loss calculation method that allows for the accurate prediction of the operational characteristics of the compressor in the post-stall regime. Three different compressor performance maps are generated for low, intermediate and high pressure stage groups using the geometry of the multistage compressor of a power generation gas turbine engine. The results are compared with the maps obtained from experiment.
Effect of Unsteady Wake Passing Frequency on Boundary Layer Transition, Experimental Investigation and Wavelet Analysis
Authors: Schobeiri M. T. , Read K. , Lewalle J.
Published: February 2015

Detailed experimental and theoretical investigations were carried out to study the effect of unsteady wake passing frequency on the boundary layer transition along the concave surface of a curved plate under a zero longitudinal pressure gradient Periodic unsteady flow with different passing frequencies is generated utilizing an unsteady flow research facility with a rotating cascade of rods positioned upstream of the curved plate. Extensive unsteady boundary layer measurements are carried out. The data are analyzed using conventional and wavelet-based methods. Local time scales are defined as those of the most energetic fluctuations, and are calculated from wavelet transforms of the velocity signals. The dominant time scales are mapped as functions of the distance to the plate, the downstream location, and the phase relative to the wake-passing. Furthermore, conditional sampling is applied, laminar turbulent time scales are calculated and the effects of wake passing frequency on these scales are shown.
Temperature Rise During Deep Surge in Centrifugal Compression System
Authors: Dai Ji , Gu Chuangang , Miao Yongmiao
Published: February 2015

A theoretical model for temperature calculation is presented to understand the tendency of temperature rise during deep surge in a low-speed centrifugal compression system. The one-dimensional aerodynamic equations of unsteady incompressible flow are employed in all components of the system. The equations are suitable to the impeller as well as the stationary parts. The one-dimensional time varied coordinate and control volume approaches for numerical scheme are used in the model. If flow rates in every deep surge cycle are provided from transients calculation or experimental data, the temperature in any position of the system can be evaluated at any step of time. A small low-pressure centrifugal compressor facility for surge experiments is set up. The dynamic measurements for flow and temperature during deep surge are implemented, and the data from measurements can be applied to verify the reliability of present model. Some phenomena can also be discovered from experimental observations. Based on the present experimental and numerical investigations, the characteristics of temperature rise during deep surge are analyzed for different volumes of system and different boundary conditions. Some results are concluded, which are valuable in engineering.
Numerical Simulations of Advanced Transonic Compressor Stages Using an Unsteady Quasi-Three-Dimensional Flow Solver
Authors: Micklow Gerald J. , Sauve J. Paul , Shivaraman Karthikeyan
Published: February 2015

This study presents the results of numerical simulations of single stage transonic axial-flow compressors. The numerical scheme used solves the unsteady quasi-three-dimensional thin-layer Navier-Stokes equations. In the first part of the study, the validation of the numerical scheme for advanced transonic axial-flow compressor stages is presented. The results of a numerical simulation are compared to an experimentally tested transonic compressor stage of DFVLR. Further simulations are performed on an advanced transonic compressor stage design to investigate the effect of airfoil geometry re-scaling, in order to save computing time, on the numerical results. Two cases are simulated: a modified geometry where less stator blades are simulated and an exact geometry where the exact geometry is modeled. Good agreement is obtained between the experimental and numerical results for the first test case, indicating the validity of the quasi-three dimensional method. The last two simulations show that any significant re-scaling of the stage geometry will have an adverse effect on overall results. All of the simulations show that the unsteady rotor-stator interactions have a significant effect on stage performance.
Blade-to-Blade Variability of the Pressure Associated With an Axial Compressor
Authors: Sherman Peter , Dudley Rachel , Suarez Mitchell
Published: February 2015

This work investigates the use of statistical and time/frequency analysis of the downstream pressure signature to characterize blade-to-blade variability of both average and residual pressure associated with a single row 36 blade axial compressor. Analysis of the average pressure signatures suggests that the blade mean pressure signatures are not identical at a 90% significance level. Analysis of the residual signatures, obtained by removing the average signatures, reveals that the wake region contains approximately four times as much power as the core flow region. Time-frequency analysis shows that the strong harmonic content which persists in the residual process is temporally concentrated in the wake flow region, but that the blade-to-blade variability of this narrowband structure is sufficient to be almost eliminated upon averaging of individual blade spectra.
Status of the Automotive Ceramic Gas Turbine Development Progrem: Year Four Progress
Authors: Nishiyama Tsubura , Iwai Masumi , Nakazawa Norio , Sasaki Masafumi , Katagiri Haruo , Handa Noritoshi
Published: February 2015

The seven-year program, designated “Research & Development of Automotive Ceramic Gas Turbine Engine (CGT Program)”, was started in 1990 with the object of demonstrating the advantageous potentials of ceramic gas turbines for automotive use. This CGT Program is conducted by Petroleum Energy Center.

The basic engine is a 100kW, single-shaft regenerative engine having turbine inlet temperature of 1350°C and rotor speed of 110000rpm.

In the forth year of the program, the engine components were experimentally evaluated and improved in the various test rigs, and the first assembly test including rotating and stationary components, was performed this year under the condition of turbine inlet temperature of 1200°C.
Performance Evaluation of a 100kW Automotive Ceramic Gas Turbine at TIT1200°C Operation in a Rotating Sub-Assembly Test
Authors: Kato Junji , Otsuka Masayosi , Sugiyama Katsuhiko
Published: February 2015

A seven-year program, designated “Research & Development of Automotive Ceramic Gas Turbine Engine (CGT Program)” conducted by Petroleum Energy Center, was started in June 1990 with the object of demonstrating the advantageous potentials of ceramic gas turbines for automotive use.

This paper describes the results of an assembly test on the rotating components including a ceramic turbine rotor and a compressor assembled in the ceramic static structure. The preliminary check-out test has been successfully accomplished under the actual engine operating condition of a turbine inlet temperature of 1200°C.
M21 Cruise Marine Combined Cycle Plant
Authors: Romanov V. I. , Zhiritsky O. G. , Kovalenko A. V. , Lupandin V. V.
Published: February 2015

The paper describes M21 cruise marine combined cycle plant for SLAVA class cruisers (COGAG arrangement). Three guided missile cruisers (Figure 1) are powered by these plants (two plants for each cruiser). During this plant development the more strict demands on weight and size had been taken into account as compared with M25 plants for merchant ships.

The paper shows technical data of M21 combined cycle plant, descriptions and design features of SPA MASHPROEKT GT 6004R gas turbine with reversible free power turbine, waste-heat recovery boiler, steam turbine with a condenser and a common gear unit.

More than 10 year service experience of these plants is shown in this paper.
Performance Analysis With Different Means of Cooling in a Combined Cycle
Authors: Singh Onkar , Yadav R.
Published: February 2015

Combined cycle based power plants and their development and application for energy efficient base load power generation necessitates enforced cooling to maintain the topping cycle gas turbine blade temperature at permissible levels, attributed to the increased turbine inlet temperature and compressor pressure ratio, for the improved performance and reliability of combined cycle. The mathematical model based on expansion path inside gas turbine considering dilution of mainstream and aerodynamic mixing losses for a range of cooling medium has been developed based on internal, film, transpiration cooling technologies and a combination of these. It is found that the appreciation of a cycle configuration as well as the optimum pressure ratio and peak temperature vary significantly with types of cooling technology adopted. Steam cooling for rotor appears to be a very potential cooling medium, when employed with an appropriate cooling technology. This paper deals with the thermodynamic analysis of turbine cooling using, different means of cooling i.e. air, water and steam.
Resonant Response of a Tapered Beam and its Implications to Blade Vibration
Authors: Balaji G. N. , Griffin J. H.
Published: February 2015

The resonant response characteristics of a tapered beam are studied using Euler-Bernoulli beam theory. The sensitivity of the beam’s maximum stress to variations in its geometry is studied for three types of harmonic pressure loading. The implications to the response of airfoil chord-wise bending modes are discussed.
A Reduced Order Approach for the Vibration of Mistuned Bladed Disk Assemblies
Authors: Yang M.-T. , Griffin J. H.
Published: February 2015

A reduced order approach is introduced in this paper that can be used to predict the steady-state response of mistuned bladed disks. This approach takes results directly from a finite element analysis of a tuned system and, based on the assumption of rigid blade base motion, constructs a computationally efficient mistuned model with a reduced number of degrees of freedom. Based on a comparison of results predicted by different approaches it is concluded that: the reduced order model displays structural fidelity comparable to that of a finite element model of the entire bladed disk system with significantly improved computational efficiency; and under certain circumstances both the finite element model and the reduced order model predict quite different response from simple spring-mass models.
The “3A-Series” Gas Turbines With HBR® Combustors
Authors: Becker B. , Schulenberg T. , Termuehlen H.
Published: February 2015

The worldwide experience of Siemens with heavy-duty gas turbines since the late 1950’s was the basis of an evolutionary process which led to today’s most advanced gas turbine models. More than 20 years ago the first V94 heavy-duty gas turbine went into operation. This 50 Hz machine and its scaled down 60 Hz counterpart, the V84 design, became standard units with about 120 machines providing any required duty from peaking to base load operation [1].
Ceramic Stationary Gas Turbine Development Program: Second Annual Summary
Authors: van Roode Mark , Brentnall William D. , Norton Paul F. , Edwards Bryan D.
Published: February 2015

A program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technologies, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts. Solar Turbines Incorporated leads a team that includes major U.S. and offshore suppliers of ceramic components, recognized test laboratories and a cogeneration enduser to develop and demonstrate ceramic insertion in a stationary gas turbine with the objectives of more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions.

The engine selected for the program, the Centaur 50 is being retrofitted with first stage ceramic blades, first stage ceramic nozzles, and a ceramic combustor liner. The engine hot section is being redesigned to accommodate the ceramic parts to the existing metallic support structure.

Detailed design of the ceramic components and of the interfacing metallic support structure has been completed. Two blade designs with different attachments and a nozzle design with a modified airfoil geometry have been developed. Three combustor liner designs are being evaluated based on monolithic tiles or rings, or integral cylinders of continuous fiber-reinforced ceramic matrix composites (CFCC). Fabrication of first generation prototype blades and nozzles is in progress. Fabrication of subscale combustor hardware has been completed.

Materials property data are being gathered in support of the ceramic component design and life prediction. Fast fracture and dynamic fatigue testing were performed for the candidate blade and nozzle materials. Creep and oxidation testing is in progress. Nondestructive methodologies are being applied to test specimens, simulated components, subscale hardware and prototype components. A Centaur 50 engine was procured and has been modified for ceramic component testing in a full-size engine configuration.
Boundary Layer Development in Axial Compressors and Turbines: Part 3 of 4 — LP Turbines
Authors: Halstead David E. , Wisler David C. , Okiishi Theodore H. , Walker Gregory J. , Hodson Howard P. , Shin Hyoun-Woo
Published: February 2015

This is Part Three of a four-part paper. It begins with Section 11.0 and continues to describe the comprehensive experiments and computational analyses that have led to a detailed picture of boundary layer development on airfoil surfaces in multistage turbomachinery.

In this part, we present the experimental evidence that we used to construct the composite picture for LP turbines that was given in the discussion in Section 5.0 of Part 1. We present and interpret the data from the surface hot-film gauges and the boundary layer surveys for the baseline operating condition. We then show how this picture changes with variations in Reynolds number, airfoil loading and nozzle-nozzle clocking.
Boundary Layer Development in Axial Compressors and Turbines: Part 4 of 4 — Computations and Analyses
Authors: Halstead David E. , Wisler David C. , Okiishi Theodore H. , Walker Gregory J. , Hodson Howard P. , Shin Hyoun-Woo
Published: February 2015

This is Part Four of a four-part paper. It begins with Section 16.0 and concludes the description of the comprehensive experiments and computational analyses that have led to a detailed picture of boundary layer development on airfoil surfaces in multistage turbomachinery.

In this part the computational predictions made using several modem boundary layer codes are presented. Both steady codes and an unsteady code were evaluated. The results are compared with time-averaged and unsteady integral parameters measured for the boundary layers. Assessments are made to provide guidance in using the predictive codes to locate transition and predict loss. Conclusions from the entire work are then presented.
Possible effects of the 1984 St. Clair River ice jam on bed changes
Authors: Kolerski Tomasz , Shen Hung Tao
Published: February 2015

This study examines the possible effect of the record ice jam of 1984 in the St. Clair River on river bed changes and conveyance. Numerical simulations were made to examine the flow and bed shear stresses during the jam formation and release periods. Simulation results indicate that the ice jam in the river did not cause a significant increase in bed shear stress compared to pre- and post-jam open water conditions. The insignificant change on bed shear stress during the ice jam period is the result of the large flow depth and the limited jam thickness. The bed shear stresses are much less than the critical shear stress for bed particle movement. This implies that the jam may not have had a significant impact on the channel conveyance.
Lorentz-violating effects in the Bose–Einstein condensation of an ideal bosonic gas
Authors: Casana Rodolfo , da Silva Kleber A. T.
Published: February 2015

We have studied the effects of Lorentz-violation in the Bose–Einstein condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. We first analyze the nonrelativistic case, at this level by using experimental data, we obtain upper-bounds for some LIV parameters. In the sequel, we have constructed the partition function for the relativistic ideal boson gas which to be able of a consistent description requires the imposition of severe restrictions on some LIV coefficients. In both cases, we have demonstrated that the LIV contributions are contained in an overall factor, which multiplies almost all thermodynamical properties. An exception is the fraction of the condensed particles.
A new holographic metal/superconductor phase transition model
Authors: Peng Yan , Xu Xiaoyang , Liu Guohua
Published: February 2015

We study a holographic superconductor model with Stückelberg mechanism in the four-dimensional AdS black hole background. We explore the effects of the model parameters on the scalar condensation and conclude that this new model allows first-order phase transitions to occur when the model parameter is above a threshold value. Finally, we examine the effects of the back-reaction parameters on the threshold values.
Review of Tevatron results: Top quark physics
Authors: Gerber Cecilia E. , Vellidis Costas
Published: February 2015

We present results on top quark physics from the CDF and D0 collaborations at the Fermilab Tevatron [Formula: see text] collider. These include legacy results from Run II that were published or submitted for publication before mid-2014, as well as a summary of Run I results. The historical perspective of the discovery of the top quark in Run I is also described.
Short-ranged interaction effects on Z2 topological phase transitions: The perturbative mean-field method
Authors: Lai Hsin-Hua , Hung Hsiang-Hsuan
Published: February 2015

Time-reversal symmetric topological insulator (TI) is a novel state of matter that a bulk-insulating state carries dissipationless spin transport along the surfaces, embedded by the Z2 topological invariant. In the noninteracting limit, this exotic state has been intensively studied and explored with realistic systems, such as HgTe/(Hg, Cd)Te quantum wells. On the other hand, electronic correlation plays a significant role in many solid-state systems, which further influences topological properties and triggers topological phase transitions. Yet an interacting TI is still an elusive subject and most related analyses rely on the mean-field approximation and numerical simulations. Among the approaches, the mean-field approximation fails to predict the topological phase transition, in particular at intermediate interaction strength without spontaneously breaking symmetry. In this paper, we develop an analytical approach based on a combined perturbative and self-consistent mean-field treatment of interactions that is capable of capturing topological phase transitions beyond either method when used independently. As an illustration of the method, we study the effects of short-ranged interactions on the Z2 TI phase, also known as the quantum spin Hall (QSH) phase, in three generalized versions of the Kane–Mele (KM) model at half-filling on the honeycomb lattice. The results are in excellent agreement with quantum Monte Carlo (QMC) calculations on the same model and cannot be reproduced by either a perturbative treatment or a self-consistent mean-field treatment of the interactions. Our analytical approach helps to clarify how the symmetries of the one-body terms of the Hamiltonian determine whether interactions tend to stabilize or destabilize a topological phase. Moreover, our method should be applicable to a wide class of models where topological transitions due to interactions are in principle possible, but are not correctly predicted by either perturbative or self-consistent treatments.
A Hybrid Model for Enhanced Prediction of Medical Diagnosis Based on Discriminative Rule Framing and Correlated Framework Approaches
Authors: Gomathy B. , Ramesh S. M. , Shanmugam A.
Published: February 2015

Medical diagnosis is mostly done by experienced doctors. However, still some of the cases reported of wrong diagnosis and treatment. Patients are needed to take number of clinical tests for disease diagnosis. Most of the cases, all the tests are not contributing towards efficient diagnosis. The medical data are multidimensional and composed of thousands of independent features. So, the multidimensional database need to be analyzed and preprocessed for valuable decision making for medical diagnosis. The aim of this work is to accurately predict the medical disease with a condensed number of attributes. In this approach, the raw input dataset is preprocessed based on the common normalization approach. An association rule is used to find out the frequent used patterns to prune the dataset. Further, base rule can be applied to the pruned dataset. The Payoff and Heuristic rate can be evaluated to predict the risk analysis. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) approaches are used for better feature selection. Classification result is acquired based on minimum and maximum of residual support values. The experimental results show that the proposed scheme, can perform better than the existing algorithms to diagnose the medical disease.
Path Optimality Conditions for Minimum Spanning Tree Problem with Uncertain Edge Weights
Authors: Zhou Jian , Chen Lu , Wang Ke
Published: February 2015

This paper investigates the uncertain minimum spanning tree (UMST) problem where the edge weights are assumed to be uncertain variables. In order to propose effective solving methods for the UMST problem, path optimality conditions as well as some equivalent definitions for two commonly used types of UMST, namely, uncertain expected minimum spanning tree (expected UMST) and uncertain α-minimum spanning tree (α-UMST), are discussed. It is shown that both the expected UMST problem and the α-UMST problem can be transformed into an equivalent classical minimum spanning tree problem on a corresponding deterministic graph, which leads to effective algorithms with low computational complexity. Furthermore, the notion of uncertain most minimum spanning tree (most UMST) is initiated for an uncertain graph, and then the equivalent relationship between the α-UMST and the most UMST is proved. Numerical examples are presented as well for illustration.
STUDY OF THE TARGETING ERROR FOR PERCUTANEOUS NEEDLE INSERTION INTO SOFT PHANTOM MATERIAL
Authors: WANG XINGJI , JIANG SHAN
Published: February 2015

Percutaneous needle insertion is widely used in minimally invasive procedures, in which the flexible needle is steered to reach a specific target inside the human body. The targeting error is due to a combination of flexible needle deflection and target displacement in soft tissue and only a very limited number of studies have focused on both two factors. This paper presents a targeting error calculation method which incorporates an energy-based needle deflection model into a soft tissue finite-element (FE) model. The needle insertion process is discretized into several increments on the basis of the quasi-static method. Needle deflection in each step is obtained by the needle-soft tissue interaction model which is applied into the FE model as the displacement input. A 2D-planar FE model is used to model the target displacement by imposing needle distribution forces and needle deflection at different steps on the appointed reference nodes. The soft tissue is modeled as a non-linear hyperelastic material with geometrical non-linearity. Uniaxial tensile strength tests are utilized to determine the soft tissue parameters. Needle targeting experiments are conducted to validate the simulation results. Results show that the proposed method can predict the needle targeting errors while the averaged prediction error stays below 0.4[Formula: see text]mm. At last, we conduct different experiments to compensate the obtained targeting error and thus, reaching preferable effects.
Interleukin‐1 as a Common Denominator from Autoinflammatory to Autoimmune Disorders: Premises, Perils, and Perspectives
Authors: Lopalco Giuseppe , Cantarini Luca , Vitale Antonio , Iannone Florenzo , Anelli Maria Grazia , Andreozzi Laura , Lapadula Giovanni , Galeazzi Mauro , Rigante Donato
Published: February 2015

A complex web of dynamic relationships between innate and adaptive immunity is now evident for many autoinflammatory and autoimmune disorders, the first deriving from abnormal activation of innate immune system without any conventional danger triggers and the latter from self‐/non‐self‐discrimination loss of tolerance, and systemic inflammation. Due to clinical and pathophysiologic similarities giving a crucial role to the multifunctional cytokine interleukin‐1, the concept of autoinflammation has been expanded to include nonhereditary collagen‐like diseases, idiopathic inflammatory diseases, and metabolic diseases. As more patients are reported to have clinical features of autoinflammation and autoimmunity, the boundary between these two pathologic ends is becoming blurred. An overview of monogenic autoinflammatory disorders, PFAPA syndrome, rheumatoid arthritis, type 2 diabetes mellitus, uveitis, pericarditis, Behçet’s disease, gout, Sjögren’s syndrome, interstitial lung diseases, and Still’s disease is presented to highlight the fundamental points that interleukin‐1 displays in the cryptic interplay between innate and adaptive immune systems.