bluuebunny/crossref_metadata_2025 huggingface dataset:
The Performance of a Surrogate Blend in Simulating the Sooting Behavior of a Practical, Distillate JP-4
Authors: Wood C. P. , Samuelsen G. S.
Published: March 2015

A surrogate fuel has been developed to simulate the atomization and combustion performance of a practical, petroleum distillate JP-4. The surrogate is comprised of fourteen pure hydrocarbons and formulated to reproduce the distillation curve and compound class composition of the parent petroleum distillate fuel. In previous work, the atomization performance (evaluated in terms of the atomization quality in an isothermal chamber), and the combustion performance (evaluated in terms of the mean axial velocity and thermal fields in a spray-atomized, swirl-stabilized, model laboratory combustor) were found to be equivalent for the petroleum and surrogate JP-4. The present study addresses the sooting performance of the two fuels, as well as that of two reference fuels (isooctane and a high aromatic petroleum JP-5) of purposefully disparate properties. The sooting performance of the petroleum and surrogate JP-4 are nearly identical, and distinctly different from that of either the isooctane or the JP-5. The surrogate represents, as a result, an attractive fuel blend for the study of fuel compositional effects on the combustion performance of practical fuels in a spray-fired combustor.
Behaviour of the Leg of the Horseshoe Vortex Around the Idealized Blade With Zero Attack Angle by Triple Hot-Wire Measurements
Authors: Honami Shinji , Shizawa Takaaki , Takahama Masayuki
Published: March 2015

The paper presents the flow measurements within the leg portion of the horseshoe vortex. An uncambered blade of constant thickness downstream with a half-circular nose of an idealized turbine blade was installed on a flat plate. The six components of the Reynolds stresses were measured in addition to the three mean velocity components at two cross-sectional planes by a triple wire probe. The predominant vortical motion of the secondary flow occurs at the corner of the blade and the endwall. The effect of the penetrative motion of the free-stream toward the corner region induced by the vortex on the Reynolds stress is found in u2 profiles near the blade, but not in v2 profiles. The diffusion of the Reynolds stresses is observed in the crossflow direction.
Gas Turbine Systems Training in the U.S. Navy: A Retrospective Analysis
Authors: Dachos John , Tobara Peter , Ulozas Bernard
Published: March 2015

Five years after the introduction of gas turbine propulsion in major U. S. Navy combatants, the engineering training pipeline, populated with cross-rates primarily from the existing machinist, engineman, and electrical ratings, consisted of a series of contractor developed block courses operationally centered around the propulsion and electrical control consoles. The rapid introduction of new ships in the late seventies and eighties required an accelerated training pipeline and the use of mostly apprentice candidates directly from recruitment. This increased need, the recognition in the fleet that existing training was not providing system knowledge, and the construction of a gas turbine training hot plant precipitated the development of a new training curriculum.

Course development was derived from documentation which dictates plant operation: the equipment/system design; the Preventive Maintenance System (PMS); the Engineering Operating Sequencing System (EOSS); Fleet commander engineering management programs; and the Ships’ Manning Document (SMD). Using a disciplined approach, essential student performance objectives were defined and necessary learning objectives developed from the above documentation. The scope of the course encompassed the “cradle to grave” concept from apprentice training through journeyman and supervisor, and necessitated incremental and refresher training throughout the career of the gas turbine mechanic and electrician.
A New Singular Integral Approach for a Vertical Array of Airfoils
Authors: Wilson Dennis
Published: March 2015

Recently, a singular integral method was developed for solving two-dimensional compressible potential flows. The original formulation limited the applicability to single bodies in a uniform freestream. Currently, modifications are being made so that the flow field around multiple bodies can also be calculated. Because of the unique manner in which the integral equations are formulated, they are especially well-suited for analysis and inverse design calculations of a row of similar airfoils. A brief description of the formulation is given in this paper and some preliminary results are included.
Helicopter Health Monitoring From Engine to Rotor
Authors: Marriott J. F. , Kaye J. F. M.
Published: March 2015

Recent tragic accidents have focused attention on the dangers of unmonitored helicopter dynamic assemblies. Methods are available to monitor the entire power train from the engine to the rotor. Apart from the obvious safety advantages, such systems offer the additional benefits of increased availability, a planned maintenance schedule and a reduction in life cycle costs.

Historically, monitoring systems have evolved from isolated processing units, each performing single functions. Hawker Siddeley Dynamics Engineering Ltd, in conjunction with Stewart Hughes Ltd is developing a modular and integrated health and usage monitoring system. After a brief discussion of health monitoring equipment evolution, this paper focuses on the practical application of the techniques required to ensure the health of the modern helicopter.
High Operation Flexibility and Reliability by Multi-Unit Compressor Arrangement for Gas Storage Applications
Authors: Neuburg Harald , Schmidt Klaus D.
Published: March 2015

The growing gas market and the increasing ratio of imported gas to gas produced within a country requires an expanded capacity for buffer gas storage to compensate for differences between constant import gas flow and seasonal variances in consumption.

For economical operation of the gas storage facility and for moving extensive quantities of gas, high operating flexibility as well as high availability and reliability of gas compression equipment are required.

This paper will report on an underground gas storage project and indicate specific objectives for the project in reservoir engineering, gas compression and free-flow withdrawal duties. It will also deal with the sizing and selection of gas turbine driven centrifugal compressor sets, including the required station equipment.

Finally, operating experience will be discussed.
Linear State Variable Dynamic Model and Estimator Design for Allison T406 Gas Turbine Engine
Authors: Vittal Rao S. , Moellenhoff D. , Jaeger J. A.
Published: March 2015

This paper describes a procedure for developing a State Variable Model for the Allison T406 gas turbine engine. This linear model is useful for designing controllers using modern control techniques. The engine and V-22 rotor system is modeled around an operating point by using four state variables and one input variable. For a given power setting, it is observed that two linear models are sufficient to represent the engine dynamics over the entire flight envelope. A relationship between surge margin and the state variables is also developed. It is demonstrated that these linear models are useful in designing an estimator for accommodating hard sensor failures.
Real Time Simulators for Use in Design of Integrated Flight and Propulsion Control Systems
Authors: Davies William J. , Jones Charlie L. , Noonan Robert A.
Published: March 2015

The introduction of Full Authority Digital Electronic Controls (FADEC) to both commercial and military aircraft gas turbine engines provides significant operational benefits. FADEC’s are reliable and more maintainable than the hydromechanical controls they have replaced. The next significant change in their use will be integration with the flight control, particularly in military applications, to provide reduced fuel consumption in cruise and rapid, accurate engine transients for increased maneuverability.

Integration with the flight control system requires another level of control system testing beyond verification that the FADEC will perform it’s principle functions-control and protection of the engine. This new testing requires that the FADEC be tested in unison with the flight control to verify total control system capability and safety throughout the flight envelope. These testing requirements have been addressed at Pratt & Whitney and various airframers through application of the same simulation tools which have been in use to verify FADEC hardware and software capability prior to engine test. These test systems and their application to advanced integrated control systems are described herein to provide insight into both their operation and application.
Gas Turbine Training in the Royal Navy
Authors: Meadows T. J.
Published: March 2015

This paper discusses the training given to the personnel of the Marine Engineering Branch of the Royal Navy to enable them to maintain and operate the main propulsion gas turbines fitted in the new generation of warships. Concentrating on the aspects appertaining to gas turbines, the paper describes the training given to both officers and enlisted men during their initial career training both ashore and at sea, and also outlines the training undertaken by personnel to prepare them for appointments to specific ships. Finally, the methods of validating this training to ensure that it meets the requirements of the Fleet are described.
Lean Low NOx Primary Zones Using Radial Swirlers
Authors: Alkabie H. S. , Andrews G. E. , Ahmad N. T.
Published: March 2015

Swirling flow primary zones with between 30% and 60% simulated primary zone air flow were investigated using curved blade radial swirlers. Two radial swirlers were compared with the same open area but different outlet diameters, d, giving different expansion ratios, D/d, from the swirler to the combustor diameter, D. Two combustors were used, 76 mm and 140 mm diameter, the larger one corresponding to the size of several gas turbine can combustors. There was no influence of D/d on the weak extinction. It was demonstrated that an adequate efficiency was not achieved in the weak region until there was a significant outer expansion and associated recirculation zone. It was shown that these systems with central gaseous fuel injection had good flame stability with very low NOx emissions. Propane and natural gas were compared and the NOx emissions were 50% lower with natural gas. The optimum NOx emissions, compatible with a high combustion efficiency, were close to 10 ppm NOx emissions corrected to 15% oxygen.
Flow Computation and Blade Cascade Design in Turbopump Turbines
Authors: Billonnet Gilles
Published: March 2015

The aerodynamic blade cascade design of a two stage axial supersonic turbine is investigated by using an inviscid flow computation method. The flow inside such kind of turbine is characterized by high inlet Mach numbers and large deflection angles as well as supersonic flow matching between stator and rotor. Most of the computed flow configurations give strong shock waves in the blade-to-blade channels, which let anticipate boundary layer separation phenomena. The inverse mode calculation is applied in order to avoid adverse pressure gradients on the walls. The semi-inverse method allows us to get the geometry of a blade profile corresponding to a given pressure distribution on the suction side and the pressure side, the solidity being fixed. A new design of the turbine blade cascade is then considered in order to achieve the desired velocity diagram.
Recent Advances in Engine Health Management
Authors: Pipe Kenneth , Fisher Celia
Published: March 2015

New measurement capabilities developed in the last five years have greatly enhanced the ability of monitoring systems to produce acceptable engine distress and maintenance information to pilots.

The more recent advances are particularly useful for military and helicopter engines. This paper describes three new techniques, with descriptions of their application. These include direct aerodynamic thrust measurement, gas path distress analysis and analysis of the dynamic behaviour of gas turbines. The paper concludes by suggesting the impact of these techniques on systems design for future engines.
A Comparison of Engine Design Life Optimization Results Using Deterministic and Probabilistic Life Prediction Techniques
Authors: Reed Edward J.
Published: March 2015

This paper documents a study conducted to determine the optimum design life of a turbine disk. The study traded weight against maintenance with the optimum being determined through a life cycle cost analysis. Both deterministic and probabilistic life prediction techniques were employed to establish maintenance frequency and cost. Comparing probabilistic with deterministic life optimization results was a major objective of this study. Both life prediction techniques resulted in the same optimum life conclusion with the probabilistic analysis giving additional insight into the decision drivers.
A New Source of Lightweight, Compact Multifuel Power for Vehicular, Light Aircraft and Auxiliary Applications: The Joint Deere Score™ Engines
Authors: Jones Charles
Published: March 2015

Deere & Co. has actively pursued development of the multifuel Wankel-type stratified charge engine since February 1984. During this period, a new R&D facility has been established where development is in progress for three new engine families having basic displacements of .66, 1.72 and 5.8 liters/rotor, for a 1 to 8 rotor engine output range from 37 to 2250kW (50 to 3000HP). The initial SCORE™ (“Stratified Charge Omniverous Rotary Engines”) production engines will be placed into service next year. This series of three engine families offers the size, weight and low vibration characteristics of small gas turbines and the fuel efficiency and initial cost characteristics of diesel engines.

This paper describes the combustion concept, relates relevant history and gives the current development status for all three basic sizes.
Pre-Swirl Blade-Cooling Effectiveness in an Adiabatic Rotor-Stator System
Authors: El-Oun Z. B. , Owen J. M.
Published: March 2015

Blade-cooling air for a high-pressure turbine is often supplied from pre-swirl nozzles attached to a stationary casing. By swirling the cooling air in the direction of rotation of the turbine disc, the temperature of the air relative to the blades can be reduced. The question addressed in this paper is: knowing the temperatures of the pre-swirl and disc-cooling flows, what is the temperature of the blade-cooling air?

A simple theoretical model, based on the Reynolds analogy applied to an adiabatic rotor-stator system, is used to calculate the pre-swirl effectiveness (that is, the reduction in the temperature of the blade-cooling air as a result of pre-swirling the flow). A mixing model is used to account for the ‘contamination’ of the blade-coolant with disc-cooling air, and an approximate solution is used to estimate the effect of frictional heating on the disc-cooling air.

Experiments were conducted in a rotor-stator rig which had pre-swirl nozzles in the stator and blade-cooling passages in the rotating disc. A radial outflow or inflow of disc-cooling air was also supplied, and measurements of the temperature difference between the pre-swirl and blade-cooling air were made for a range of flow rates and for rotational Reynolds numbers up to Reθ = 1.8 × 106. Considering the experimental errors in measuring the small temperature differences, good agreement between theory and experiment was achieved.
Material Property Measurements on Thermal Barrier Coatings
Authors: Berndt Christopher C.
Published: March 2015

The material property measurements of thermal barrier coatings from cyclic furnace, thermal rig, thermal expansion, acoustic emission and tensile adhesion test methods are critically examined. Some basic engineering properties of coatings such as the elastic modulus have not been measured without ambiguity. Data of this nature is essential to the success of modeling studies.

Insights into the mechanical properties of coatings have been gained by carrying out instrumented tensile adhesion tests. The general view of the coating deformation process is that the individual lamellae slide over each other and this promotes a “pseudo-ductility” response in the coating. Monitoring of the acoustic emission response of coatings during thermal cycling experiments suggests that there are two distinct cracking processes. The macro-cracking behaviour, indicated by a change in the acoustic emission count rate, is the predominant mechanism which leads to coating failure.

It is further shown that the acceptance tests used by industry, although useful in ranking coatings in terms of a particular property, present no fundamental knowledge concerning the material properties of coatings. It is only when the phenomenological characteristics of the thermo-mechanical response of coatings is understood that coating development will substantially progress.
Porosity Determination of Thermal Barrier Coatings
Authors: Van Roode Mark , Beardsley Brad
Published: March 2015

Coating porosity is believed to be a critical factor for the thermal conductivity of thermal barrier coatings (TBC’s). A number of different techniques have been used to determine the porosities of thermal barrier coatings for diesel applications as part of a NASA/DOE sponsored study. A comparison is made between methods based on water immersion, optical microscopy, eddy current thickness measurements, and Archimedes principle for TBC porosity determination.
Weibull Analysis Techniques on a Desktop Computer
Authors: Byers J. L.
Published: March 2015

This paper presents a summary of a task to provide individual Navy project engineers with analytical tools that enable them to perform Weibull failure and related analyses on a desktop computer. Similar tools have been available on mainframe computers for over a decade while only fragmented and incomplete tools existed for desktop computers. There is now available an integrated computer program that allows Navy project engineers and other Navy analysts to perform rigorous trade-off and what-if analyses in an interactive manner without having to send the problem off to their organizational central computer facility. The resulting computer codes exist in several forms to fit the various needs and computer configurations, such as: direct input of data, data file creation and update, and non-printing versions for those who have no printer available. Included in the codes are three Monte Carlo routines and several test plan generation codes. These codes have not been released to the general public as yet and are currently restricted to Navy units such as laboratories, Naval Aircraft Rework Facilities (NARF) and the Naval Air Systems Command Headquarters (NAVAIR). Public release is expected in mid-FY 89.
The CFM56 Engine Family: An International Development
Authors: Spence L. M. , Sangis Georges
Published: March 2015

During the 1970’s General Electric of the United States and Societe Nationale d’Etude et de Construction de Moteurs d’Aviation (SNECMA) of France took advantage of a unique market opportunity to develop a modern, fuel efficient, quiet turbofan engine in the 20000 to 25000# thrust class. Both companies had confidence that there would be a significant demand for such an engine to warrant the large total investment of both money and resources.
Teaming: A Case Study
Authors: White Steven D. , Wolfe Robert A.
Published: March 2015

Textron Lycoming and Pratt&Whitney teamed to develop the T800 for the Army’s LHX program and other applications. A teamed approach was selected in order to answer the Army’s requirement for true competition during the production phase of the program. Clear definition of this requirement, while not specifying teaming as absolutely necessary, was a critical element in the rapid and smooth initiation of the teamed effort. Additional key elements were management compatibility, equal technical contribution, willingness to transfer technology, and team focus on a clear goal.

An organization was structured which utilizes a Joint Program Office (JPO) as the managing unit. This office is located at Stratford, Connecticut, and is staffed by Textron Lycoming and Pratt&Whitney personnel. The JPO structure has been successful in forcing the joint decision process to function within both organizations. This case study focuses on the process of teaming for the development of complex systems. It addresses initiation of the team, management structure, unique management issues, benefits to participants and customers, and lessons learned.
Development of the F404/RM12 for the JAS 39 Gripen
Authors: Larsson L. , Veno L. B. , Daub W. J.
Published: March 2015

A new military aircraft — JAS 39 GRIPEN — is now under development in Sweden (Figure 1). JAS stands for “Jakt” (Fighter), “Attack” and “Spaning” (reconnaissance). This multi-mission combat aircraft uses a single RM12 version of the General Electric F404 augmented turbofan engine.
Austenitic High-Performance Materials for Non-Rotating Components in Stationary Gas Turbines
Authors: Drefahl K. , Hofmann Franz
Published: March 2015

Five essential requirements for gas turbine materials exposed to high temperatures are discussed:

- High resistance to oxidation and high temperature corrosion

- High creep strength especially under condition of thermal stress

- High fatigue strength under conditions of vibrational and thermal stress

- Good workability since complicated deformation and machining processes are often necessary

- Good weldability

It is not always possible to make all these requirements totally compatible. This is because certain requirements have to be emphasized for reasons of application. In most cases compromises will have to be made in regard to workability.
Experience With Supplementary Combustion Systems to Maximize Steam Production in Gas Turbine Cogeneration Plants
Authors: Backlund J. C. , Fiorenza E. E.
Published: March 2015

Topping cycle cogeneration plants, consisting of a relatively small gas turbine generator (3–5 MW) and a supplementary fired heat recovery steam generator designed to maximize steam production, are becoming a very attractive system design. Special burners designed to fire into water wall furnaces can add substantial steam production capability to the system in a very efficient manner, utilizing the oxygen available in the turbine exhaust.

This paper examines recent operating experience at two U.S. installations, using gas turbines rated at 3.3 MW (Iso) and 4. 8 MW (Iso). Gas fired burner designs are presented. Performance parameters such as response to load, maximum steam production, burner rangeability, and emissions of NOx and CO are discussed.
The PGT 10 Heavy Duty 10 MW Gas Turbine
Authors: Gusso R. , Benvenuti E. , Bianchi D. , Sabella D.
Published: March 2015

The PGT 10 two-shaft, 10 MW, industrial gas turbine has a capability of up to 34% simple-cycle efficiency, high reliability with extended range of operation and low exhaust emissions. Features like the 14:1 pressure ratio and high specific mass flow transonic axial compressor are at the highest levels in the heavy-duty gas turbine design. The firing temperature, the blade cooling techniques, the extended modularization of components and subassemblies are in their turn representative of the well-proven, state-of-art technology: performance results also from the aero-thermodynamic design aimed at maximizing component efficiencies.

This paper introduces the major aspects of the PTG 10 turbine design. After full-load testing was successfully completed on the first units, the PTG 10 has entered normal production in 1987 and several units have already been installed or shipped.
Transition Modeling Effects on Viscous/Inviscid Interaction Analysis of Low Reynolds Number Airfoil Flows Involving Laminar Separation Bubbles
Authors: Walker G. J. , Subroto P. H. , Platzer M. F.
Published: March 2015

Estimating the low Reynolds number and off-design performance of axial turbomachine blades requires an accurate prediction of separation phenomena occurring on the blade surface. This paper discusses a viscous/inviscid interaction analysis of flow over a NACA 65-213 airfoil at a chord Reynolds number of 240,000 using a calculation method of Cebeci et al. The computed characteristics of a mid-chord laminar separation bubble are compared with experimental laser-doppler anemometer measurements of Hoheisel et al. Attention is focused on problems of modeling the laminar-turbulent transition zone within the viscous layer.

A parametric study is undertaken to determine the location and extent of the transition zone which best models the observed separation bubble behavior. The required transition length is almost an order of magnitude smaller than that predicted from conventional transition length correlations. A physical model for this greatly reduced transition length in positive pressure gradient flows is proposed.

The computational model correctly predicts most features of the separation bubble flow, but there are some significant discrepancies at reattachment which point to the need for improved turbulence modeling in this area. The inclusion of transverse pressure gradients associated with flow curvature in the viscous regions also appears very desirable for airfoils operating at Reynolds numbers around 105.
Evaluation of Potential Engine Concepts for a High Altitude Long Endurance Vehicle
Authors: Kowalski Edward J.
Published: March 2015

A potential need has been identified for a High Altitude Long Endurance (HALE) aircraft to augment current surveillance and engagement capability. HALE platforms offer mission flexibility and survivability which can complement ground based surveillance and engagement systems. Current mission requirements include a loiter altitude of 45,000 to 60,000 feet and a loiter time of 12 to 24 hours. The HALE aircraft will also be required to carry a sensor payload weight between 50,000 and 100,000 pounds. This paper will evaluate the potential of several propulsion system candidates. Engines to be examined include the “classical” turbofan engine with bypass ratios up to eight, the “ultra high bypass ratio” turbofan with bypass ratios up to 20, General Electric’s Unducted Fan (UDF) and the turboprop in a pusher and tractor configuration with single and counter rotation propfans.
An Experimental Investigation Into the Reasons of Reducing Secondary Flow Losses by Using Leaned Blades in Rectangular Turbine Cascades With Incidence Angle
Authors: Zhongqi Wang , Wenyuan Xu , Wanjin Han , Jie Bai
Published: March 2015

Up to now the reasons of reducing the secondary flow losses by using leaned blades, especially in the case of great incidence angle, have been little concerned with in published references. The experimental results in this paper have shown that the decisive factor reducing secondary flow losses in turbine stator cascades is the static pressure gradient along the blade height inside the cascade channel near the suction surface, especially in the rear part of it, because the negative pressure gradient in the hub region and the positive one in the tip region are beneficial for the boundary layer in both the regions to be sucked into the main stream region, consequently, the accumulation and the separation of the boundary layer have been weakened in both regions. Moreover, the effectiveness of applying the positively or negatively leaned blades is increased with the increase of a incidence angle, in the hub or the tip regions respectively.
Calculation of the Flow Along the S1 Stream Surface With Inviscid-Viscous Interaction Method
Authors: Shun Kang , Yongshen Huang , Zhongqi Wang
Published: March 2015

As an extension of the author’s previous work, this paper proposes a mixed iterative method for calculating the interactions of boundary layer with inviscid flow on S1 stream surface. It is shown from the comparison with experimental results that the iteration method given in this paper has a high calculation accuracy. In addition, the rate equation of the entrainment coefficient adapted for the turbulent boundary layer in the S1 stream surface has been established in this paper. The predicted results show that taking this equation as the supplemental equation for solving the turbulent boundary layer on cascade blades can improve the accuracy of calculation of the turbulent boundary layer on cascade blades.
3-D Laser Anemometer Measurements in an Annular Seal
Authors: Morrison G. L. , Johnson M. C. , Tatterson G. B.
Published: March 2015

The flow field inside an annular seal with a 0.00127 m clearance was measured using a 3-D laser Doppler anemometer system. Through the use of this system, the mean velocity vector and the entire Reynolds stress tensor distributions were measured for the entire length of the seal (0.0373 m). The seal was operated at a Reynolds number of 27,000 and a Taylor number of 6,600.
The Relative Merits of an Inviscid Euler 3-D and Quasi-3-D Analysis for the Design of Transonic Rotors
Authors: Miller D. P. , Bryans A. C.
Published: March 2015

It is the purpose of this paper to examine the flow fields in an advanced modern transonic rotor design using both axisymmetric and three dimensional techniques. Also, to determine the deviation of the axisymmetric flow from three-dimensional flow field and whether this seriously affects the results. Inviscid Euler solvers are now widely used to analyze transonic flows through turbomachines giving a reasonably accurate indication of the flow field in blade passages. Although viscous effects are important, the inviscid analysis provides significant knowledge of the flow field which is essential to transonic design. The blade-to-blade loading and work distributions are determined quite realistically by the 3-D and quasi-3-D inviscid analyses. Through-flow and blade-to-blade inviscid solutions are presented for a highly loaded transonic rotor. Numerical solutions for various transonic rotor designs operating at peak efficiency are also compared with test data.
Use of Control Feedback Theory to Understand Other Oscillations
Authors: Rumford K. J. , Andrejczyk R.
Published: March 2015

The TF40B control system and the rotor system of the U.S. Navy LCAC Hovercraft are described. A history of early development problems and their solution is followed by a more obscure problem that was traced by logical deduction to a mechanical vibration of a control component. This vibration resulted in fuel flow oscillations that fed back and amplified the mechanical vibration. The solution to this problem is described and a unique application of classical closed loop control analysis to this unusual and unwanted feedback follows.
Numerical Solution to Transonic Potential Equations on S2 Stream Surface in a Turbomachine
Authors: Du J. Y. , Zhao Y. Q. , Guo Y. , Xu J. Z.
Published: March 2015

A non-isentropic potential method on a S2 stream surface has been developed for the design and analysis of transonic compressors with shocks, in which the entropy increase across a shock may be directly calculated from the momentum equations in the divergence form. The numerical results show that the non-isentropic shock is weaker and placed one or two meches further upstream compared to the classical potential calculation, and is in good agreement with the experimental data.
On the Prediction of Unsteady Forces on Gas-Turbine Blades: Part 1 — Typical Results and Potential-Flow-Interaction Effects
Authors: Korakianitis Theodosios P.
Published: March 2015

This paper is a contribution to the study of the generation of unsteady forces on turbine blades due to potential-flow interaction and viscous-wake interaction from upstream blade rows. A computer program is used to compute the unsteady forces on a rotor. The accuracy of the computer program is tested by comparing the results of a steady-flow calculation case and of an unsteady-flow calculation case with theory and experiment respectively. Results are shown for typical stator-to-rotor-pitch ratios and stator outlet-flow angles. These results show that the first spatial harmonic of the unsteady force may decrease for higher stator-to-rotor-pitch ratios. This trend is explained by considering the mechanisms by which the unsteady forces are generated. In this paper the mechanism by which the potential-flow interaction affects the flow field to generate these unsteady forces is shown to vary with the stator-to-rotor-pitch ratio and with the outlet flow angle of the stator.
A comparison of finite element and analytic models of acoustic scattering from rough poroelastic interfaces
Authors: Bonomo Anthony L. , Isakson Marcia J. , Chotiros Nicholas P.
Published: March 2015

The finite element method is used to model acoustic scattering from rough poroelastic surfaces. Both monostatic and bistatic scattering strengths are calculated and compared with three analytic models: Perturbation theory, the Kirchhoff approximation, and the small-slope approximation. It is found that the small-slope approximation is in very close agreement with the finite element results for all cases studied and that perturbation theory and the Kirchhoff approximation can be considered valid in those instances where their predictions match those given by the small-slope approximation.
Parents’ Beliefs and Intentions Toward Supporting Physical Activity Participation for Their Children With Disabilities
Authors: Jeong Mihye , Kim So-Yeun , Lee Euikyung
Published: March 2015

The purpose of this study was to examine validity and reliability evidence of a questionnaire regarding parents’ beliefs and intentions toward supporting physical activity (PA) participation of their children with disabilities (CWD). A total of 220 parents of CWD in South Korea completed a questionnaire that was developed using the theory of planned behavior (TPB). Exploratory factor analysis revealed that behavioral, control, and normative beliefs accounted for 31.13%, 20.45%, and 19.63% of the total variance of the intention, respectively. Reliability of entire scale was .85 using Cronbach’s alpha. Reliabilities of the 3 beliefs were .86, .82, and .87, respectively. Standard multiple-regression analysis indicated that behavioral and normative beliefs significantly predicted parents’ intention, p < .01. Intention was a significant predictor of parents’ behavior, p < .01. The results of this study indicated that the TPB can be useful to examine parental support for PA participation of their CWD.
Selective dopamine detection using aptamer-functionalized glassy carbon electrodes
Authors: Walsh Ryan , Ho Uyen , Wang Xiao Li , DeRosa Maria C.
Published: March 2015

The electrochemical detection of dopamine using glassy carbon electrodes suffers from a lack of selectivity toward the neurotransmitter, as interferences such as other catechol-containing neurochemicals and ascorbic acid can be oxidized at overlapping potentials. Several approaches have been employed to improve the selectivity of these electrodes towards dopamine including electrochemical pretreatment and organic monolayer depositions. Here, we characterize glassy carbon electrodes that were initially passivated through a trifluoromethylphenyl and nitrophenyl monolayer deposition and then functionalized with a specific DNA dopamine aptamer. Passivation with the mixed monolayer cuts off all signals from the redox-active neurochemicals. After functionalization with the DNA aptamer, the dopamine signal is restored and the electrodes are more responsive to dopamine than to any other related catechol-containing compounds or other common neurochemicals such as ascorbic acid. Our findings indicate that aptamer functionalization of glassy carbon electrodes may provide a viable approach for tuning the selectivity of electrochemical detection.
Reactive programming of simulations in physics
Authors: Boussinot Frédéric , Monasse Bernard , Susini Jean-Ferdy
Published: March 2015

We consider the Reactive Programming (RP) approach to simulate physical systems. The choice of RP is motivated by the fact that RP genuinely offers logical parallelism, instantaneously broadcast events, and dynamic creation/destruction of parallel components and events. To illustrate our approach, we consider the implementation of a system of Molecular Dynamics, in the context of Java with the Java3D library for 3D visualization.
EFFECTS OF TREATMENT, AWARENESS AND CONDOM USE IN A COINFECTION MODEL FOR HIV AND HCV IN MSM
Authors: PINTO CARLA M. A. , CARVALHO ANA
Published: March 2015

We develop a new a coinfection model for hepatitis C virus (HCV) and the human immunodeficiency virus (HIV). We consider treatment for both diseases, screening, unawareness and awareness of HIV infection, and the use of condoms. We study the local stability of the disease-free equilibria for the full model and for the two submodels (HCV only and HIV only submodels). We sketch bifurcation diagrams for different parameters, such as the probabilities that a contact will result in a HIV or an HCV infection. We present numerical simulations of the full model where the HIV, HCV and double endemic equilibria can be observed. We also show numerically the qualitative changes of the dynamical behavior of the full model for variation of relevant parameters. We extrapolate the results from the model for actual measures that could be implemented in order to reduce the number of infected individuals.
EFFECTS OF ACUTE GLOBAL ISCHEMIA ON RE-ENTRANT ARRHYTHMOGENESIS: A SIMULATION STUDY
Authors: LU WEIGANG , LI JIE , YANG FEI , LUO CUNJIN , WANG KUANQUAN , ADENIRAN ISMAIL , ZHANG HENGGUI
Published: March 2015

Sudden cardiac death is mainly caused by arrhythmogenesis. For a functional abnormal heart, such as an ischemic heart, the probability of arrhythmia occurring is greatly increased. During myocardial ischemia, re-entry is prone to degenerate into ventricular fibrillation (VF). Therefore it has important meaning to investigate the intricate mechanisms underlying VF under an ischemic condition in order to better facilitate therapeutic interventions. In this paper, to analyze the functional influence of acute global ischemia on cardiac electrical activity and subsequently on re-entrant arrhythmogenesis, we take into account three main pathophysiological consequences of ischemia: hyperkalaemia, acidosis, and anoxia, and develop a 3D human ventricular ischemic model that combines a detailed biophysical description of the excitation kinetics of human ventricular cells with an integrated geometry of human ventricular tissue which incorporates fiber direction anisotropy and the stimulation activation sequence. The results show that under acute global ischemia, the tissue excitability and the slope of ventricular cellular action potential duration restitution (APDR) are greatly decreased. As a result, the complexity of VF activation patterns is reduced. For the three components of ischemia, hyperkalaemia is the dominant contributor to the stability of re-entry under acute global ischemia. Increasing [K+]o acts to prolong the cell refractory period, reduce the tissue excitability and slow the conduction velocity. Our results also show that VF can be eliminated by decreasing cellular excitability, primarily by elevating the concentration value of extracellular K+.
V-VARIABLE IMAGE COMPRESSION
Authors: MENDIVIL FRANKLIN , STENFLO ÖRJAN
Published: March 2015

V-variable fractals, where V is a positive integer, are intuitively fractals with at most V different "forms" or "shapes" at all levels of magnification. In this paper, we describe how V-variable fractals can be used for the purpose of image compression.
Volterra calculus and the variation formulas for the equivariant Ray–Singer metric
Authors: Wang Yong
Published: March 2015

In this paper, using the Greiner's approach to heat kernel asymptotics, we give new proofs of the equivariant Gauss–Bonnet–Chern formula and the variation formulas for the equivariant Ray–Singer metric, which are originally due to Bismut and Zhang.
Myoglobin-based non-precious metal carbon catalysts for an oxygen reduction reaction
Authors: Onoda Akira , Tanaka Yuta , Ono Toshikazu , Takeuchi Shotaro , Sakai Akira , Hayashi Takashi
Published: March 2015

A non-precious metal catalyst (NPMC) promoting a four-electron oxygen reduction reaction (ORR) was synthesized by heat treatment of myoglobin (Mb) containing a heme (iron protoporphyrin IX) as a source of iron, nitrogen, and carbon atoms. Samples of the mixture of Mb and carbon black (Vulcan XC72R: VC) were pyrolyzed at 740, 840, 940, 1040 or 1140°C under N2flow. The microstructures of the carbonized Mb catalysts were characterized by XRD, Raman spectroscopy, XPS, and TEM. Results indicate that the iron-containing active site is embedded within the surface structure in an amorphous domain of the carbon materials. The catalyst ink in a 0.05 wt% Nafion solution in isopropanol was coated onto a glassy carbon electrode and the ORR activity of Mb-based NPMCs was evaluated in a rotating disk electrode experiment in an O2-saturated 0.1 M HClO4solution at 25°C. The catalyst synthesized at 940°C has the highest ORR activity in terms of the onset potential and the current density. In contrast, pyrolytic temperatures above 940°C decrease the activity, suggesting that the active structure of the catalyst apparently decomposes at higher temperatures. The Koutecky–Levich plots indicate that the Mb-based catalyst prepared at 940°C catalyzes four-electron ORR (n = ca. 4). The catalysts prepared at other temperatures have n values of 3.6 at 740°C, 3.7 at 840°C, and 2.9 at 1040°C. The ORR of Mb/VC is diffusion-controlled at potentials lower than 0.3 V (vs. RHE) and the onset potential is 0.84 ± 0.01 V.
On Uncertainty Relations and Entanglement Detection with Mutually Unbiased Measurements
Authors: Rastegin Alexey E.
Published: March 2015

We formulate some properties of a set of several mutually unbiased measurements. These properties are used for deriving entropic uncertainty relations. Applications of mutually unbiased measurements in entanglement detection are also revisited. First, we estimate from above the sum of the indices of coincidence for several mutually unbiased measurements. Further, we derive entropic uncertainty relations in terms of the Rényi and Tsallis entropies. Both the state-dependent and state-independent formulations are obtained. Using the two sets of local mutually unbiased measurements, a method of entanglement detection in bipartite finite-dimensional systems may be realized. A certain trade-off between a sensitivity of the scheme and its experimental complexity is discussed.
Nonequilibrium Thermodynamic State Variables of Human Self-Paced Rhythmic Motions: Canonical-Dissipative Approach, Augmented Langevin Equation, and Entropy Maximization
Authors: Kim S. , Gordon J. M. , Frank T. D.
Published: March 2015

Nonequilibrium thermodynamic state variables are derived for a stochastic limit-cycle oscillator model that has been used in motor control research to describe human rhythmic limb movements. The nonequilibrium thermodynamic state variables are regarded as counterparts to the thermodynamic state variables entropy, internal energy, and free energy of equilibrium systems. The derivation of the state variables is based on maximum entropy distributions of the Hamiltonian energy of the stochastic limit-cycle oscillators. The limit-cycle oscillator model belongs to the class of canonical-dissipative systems, on the one hand, and, on the other hand, can be cast into the form of an augmented Langevin equation. Both concepts are known as physical models for open systems. Experimental data from paced and self-paced pendulum swinging experiments are presented and estimates for the nonequilibrium thermodynamic state variables are given. Entropy and internal energy increased with increasing oscillation frequency both for the paced and self-paced conditions. Interestingly, the nonequilibrium free energy decayed when oscillation frequency was increased, which is akin to the decay of the Landau free energy when the control parameter is scaled further away from its critical value.
THE NEGATIVE EFFECT OF A PERCEIVED LACK OF AN INSTALLED BASE ON TECHNOLOGY ADOPTION
Authors: SCHWEITZER FIONA M.
Published: March 2015

In this paper, I analyse the impact that a perceived lack of an installed base has on the adoption of technological products. I use the Technology Acceptance Model (TAM), which considers perceived usefulness and ease-of-use as the central drivers of adoption and propose that the perceived lack of an installed base influences these two drivers. Based on cue utilisation theory, I further suggest that a perceived lack of an installed base can serve as an extrinsic cue of product quality deficiencies and difficulties with obtaining help and advice. In order to verify the supposed effect of a perceived lack of an installed base, I survey 162 households. The data shows that a perceived lack of an installed base of thermal solar systems (1) decreases their perceived usefulness and perceived ease-of-use and (2) acts as a mediator of the perceived risk. The study implies that managers launching technical innovations should develop strategies to influence consumers' perceptions of the current and the future installed base and communicate the development of the installed base to trigger adoption.
IMPAIRMENT OF NON-PHAGOCYTOSIS-ASSOCIATED OXIDATIVE BURST TOACTINOBACILLUS PLEUROPNEUMONIAEIN PORCINE NEUTROPHILS INDUCED BY PSEUDORABIES VIRUS
Authors: Hung Steven Yi , Wang Fun-In
Published: March 2015

In industrial swine production, several important viral diseases are frequently complicated with bacterial infections, suggestive of virus–bacteria synergism. Although most virus-induced leukocyte dysfunctions are attributed to monocytes and lymphocytes, the role of polymorphonuclear cells (PMNs, mainly neutrophils) should not be excluded, because they are the first leukocytes to respond to inflammation. Previous studies indicated that pseudorabies virus (PrV) blocked the indirect recruitment of PMNs by inhibiting the production of interleukin-8 by primed peripheral blood mononuclear cells (PBMCs) and also reduced the phorbol 12-myristate 13-diacetate (PMA)-induced oxidative burst (OB) in PMNs. This study used PrV as a model to explore other possibilities of virus-induced PMN dysfunctions in pigs. The goals were: (1) to develop assay for simultaneous evaluation of phagocytosis and OB to Actinobacillus pleuropneumoniae (APP) and (2) to evaluate whether PrV could affect these responses to APP in an ex vivo setting. Approximately 12% of the PMNs underwent phagocytosis, as indicated by the presence of intracellular propidium iodide(PI)-labeled APP (PI-APP), and 32% of the PMNs launched OB to APP, as detected by dihydrorhodamine (DHR). Approximately 86% of those OB responsive cells did not contain engulfed PI-APP, and the OB was presumably induced by the bacteria lipopolysaccharide (LPS). Only 5 ± 1% of the cells underwent simultaneous phagocytosis and OB. Under certain conditions, PrV reduced the non-phagocytosis-associated OB by approximately 40% (p < 0.05), while the phagocytosis was unaffected overall. These results suggest that PrV may interfere with bacteria LPS-mediated signaling, suggesting a possibility of PrV-APP synergism in causing pneumonia.
Parallel algorithms for matroid intersection and matroid parity
Authors: Huang Jinyu
Published: March 2015

A maximum linear matroid parity set is called a basic matroid parity set, if its size is the rank of the matroid. We show that determining the existence of a common base (basic matroid parity set) for linear matroid intersection (linear matroid parity) is in NC2, provided that there are polynomial number of common bases (basic matroid parity sets). For graphic matroids, we show that finding a common base for matroid intersection is in NC2, if the number of common bases is polynomial bounded. To our knowledge, these algorithms are the first deterministic NC algorithms for matroid intersection and matroid parity. We also give a new RNC2 algorithm that finds a common base for graphic matroid intersection. We prove that if there is a black-box NC algorithm for Polynomial Identity Testing (PIT), then there is an NC algorithm to determine the existence of a common base (basic matroid parity set) for linear matroid intersection (linear matroid parity).