bluuebunny/crossref_metadata_2025 huggingface dataset:
Erosion Study of Radial Flow Compressor With Splitters
Authors: Elfeki Salah , Tabakoff Widen
Published: April 2015

Gas turbine engines operating in areas where the atmosphere is polluted by small solid particles are examples of machines operating under particulate two phase flow conditions. The presence of solid particles in the working media leads to erosion and loss of engine power. In the present paper, particle trajectories are calculated by direct integration of the particle equations of motion through a compressor impeller with two different size splitters. Particle collisions with the blade, hub and casing surfaces are determined. Erosion caused by the particle collisions with the compressor surfaces are calculated.
Lifetime Prediction Under Constant Load Creep Conditions for a Cast Ni-Base Superalloy
Authors: Castillo R. , Koul A. K. , Toscano E. H.
Published: April 2015

Creep and stress-rupture properties of cast IN738LC turbine blades have been analyzed to review the suitability of the Monkman-Grant relationship as a reliable life prediction method where

t r ε . s m = C

and m and C are material constants. The constants m and C in the Monkman-Grant relationship are temperature dependent and the relationship predicts lives within a factor of ± 4 relative to the observed values. A modified form of this relationship is derived where,

- b t r n 1 + t r ε . s m 1 = K

and b, n, m1 and K are material constants. The modified relationship is more accurate and predicts lives within a factor of 2 relative to the observed values. The constants b, n, m and k are independent of stress and temperature.
Aeroelastic Behavior of Low Aspect Ratio Metal and Composite Blades
Authors: White James F. , Bendiksen Oddvar O.
Published: April 2015

The aeroelastic stability of titanium and composite blades of low aspect ratio is examined over a range of design parameters, using a Rayleigh-Ritz formulation. The blade modes include a plate-type mode to account for chordwise bending. Chordwise flexibility is found to have a significant effect on the unstalled supersonic flutter of low aspect ratio blades, and also on the stability of tip sections of shrouded fan blades. For blades with a thickness of less than approximately four percent of chord, the chordwise, second bending, and first torsion branches are all unstable at moderately high supersonic Mach numbers. For composite blades, the important structural coupling between bending and torsion cannot be modeled properly unless chordwise bending is accounted for. Typically, aft fiber sweep produces beneficial bending-torsion coupling that is stabilizing, whereas forward fiber sweep has the opposite effect. By using crossed-ply laminate configurations, critical aeroelastic modes can be stabilized.
The Development of the Profile Boundary Layer in a Turbine Environment
Authors: Hourmouziadis J. , Buckl F. , Bergmann P.
Published: April 2015

Cascade testing tries to simulate the actual flow conditions encountered in a turbine. However, it is neither possible to reproduce the free stream turbulence structure of the turbomachinery, nor the periodic wake effects of upstream blade rows. The usual understanding is that the latter in particular results in a significantly different behaviour of the boundary layer in the engine.

Experimental results from cascades and turbine rigs are presented. Grid generated free stream turbulence structure is compared to that in the turbine. Measurements of the profile pressure distribution, flush mounted hot films and flow visualization were used for the interpretation of the test results. Some observations of the boundary layer development in the cascade, on the guide vanes and on rotor blades with typically skewed boundary layers are shown indicating essentially similar behaviour in all cases.
Part-Load Behavior of a Solar-Heated and Fossil-Fuelled Gas Turbine Power Plant
Authors: Bammert K. , Lange H.
Published: April 2015

Solar energy can be converted effectively into electrical or mechanical energy. The radiant heat of the sun is collected by a parabolic dish, concentrated intensely and reflected into a cavity receiver. Air flowing through tube panels in front of the receiver inner walls absorbs the radiant energy. Downstream of the receiver is a fossil-fired combustion chamber (hybrid construction). The fuel energy is converted at a higher utilization than in a straight fossil-fuelled power plant. The overall efficiency of the hybrid plant rises with increasing turbine inlet temperature. The power delivered by the turbine serves to drive the compressor and the generator. A description of the thermodynamic design of the cycle is followed by statements on the performance characteristics of the individual components and by a description of the steady-state part-load behavior of the plant considering specific conditions such as variations in solar and fossil fuel-generated heat and fluctuating load on the power transmission grid.
Fatigue Crack Growth Resistance of Advanced Blade Materials
Authors: Wilson D. A. , Deluca D. P. , Cowles B. A. , Stucke M. A.
Published: April 2015

The best measure of performance in a jet engine is the thrust-to-weight ratio. Cast single-crystal superalloys provide higher temperature capability and offer opportunities for significant improvements in future jet engine performance and durability. The highly anistropic behavior of these advanced materials, which includes modulus, strength, and ductility variation with crystallographic orientation, pose potentially significant problems for design and life prediction of advanced turbine blades.

The objective of this paper is to provide a better understanding of the crack growth behavior in this advanced turbine blade material by evaluating the effect of temperature, frequency, orientation, and thickness.
Experimental Investigation of Boundary Layer Separation With Heated Thin-Film Sensors
Authors: Pucher P. , Göhl R.
Published: April 2015

The heated thin-film method was adapted to meet the requirements of investigations on boundary layer behaviour in a turbine rig. Special multi-sensor probes of vaporized nickel on a polyimide foil were developed and applied to the vanes.

Basic experiments with an airfoil in a free stream were carried out and a reliable interpretation of the thin-film results was found by comparison with pressure distribution, flow visualization and laser measurements. It can be shown that this measuring device is a suitable method for the investigation of separation bubbles and boundary layer transition.
Computation of Three-Dimensional, Rotational Flow Through Turbomachinery Blade Rows for Improved Aerodynamic Design Studies
Authors: Subramanian S. V. , Bozzola R. , Povinelli Louis A.
Published: April 2015

The performance of a three dimensional computer code developed for predicting the flowfield in stationary and rotating turbomachinery blade rows is described in this study. The four stage Runge-Kutta numerical integration scheme is used for solving the governing flow equations and yields solution to the full, three dimensional, unsteady Euler equations in cylindrical coordinates. This method is fully explicit and uses the finite volume, time marching procedure. In order to demonstrate the accuracy and efficiency of the code, steady solutions were obtained for several cascade geometries under widely varying flow conditions. Computed flowfield results are presented for a fully subsonic turbine stator and a low aspect ratio, transonic compressor rotor blade under maximum flow and peak efficiency design conditions. Comparisons with Laser Anemometer measurements and other numerical predictions are also provided to illustrate that the present method predicts important flow features with good accuracy and can be used for cost effective aerodynamic design studies.
Deposition Control Using Transpiration
Authors: Kozlu Hamdi , Louis Jean F.
Published: April 2015

An experimental and theoretical study of deposition of small particles is presented to evaluate the concept of transpiration as a deposition control strategy. The application of this work is the control of deposition of small particles (1–5μm) contributing most of the mass of the solid carryover entering turbines burning fuels derived from coal. The experimental study is carried out in a wind tunnel facility containing a flat porous transpired section. The Reynolds and Stokes numbers are chosen to be representative of the conditions found in industrial gas turbines. Measurements of the velocity profiles were conducted for high injection rates (1.5%<F<3%). A theory developed for the transpired turbulent boundary layer, which is described by an “outer boundary layer” entraining the injected flow for large injection rates, agrees well with the experimental data. Concentration profiles of glass particles of both very narrow and wide size distributions were conducted for different injection rates under the isothermal conditions. The measurements clearly indicate the conditions under which transpiration can avoid the deposition of particles and they show the effect of particle size on the concentration profiles and consequently on the arrival rates. The study also provides a clear insight into the turbulent diffusion of particles for a Stokes number of between 1 and 3.5. The Schmidt numbers obtained from the measurements are in agreement with the theoretical prediction of Tchen.
Analytical Tools for the Analyses of Coal and its Combustion Products
Authors: Raj S. , Raj R.
Published: April 2015

Coal, due to its heterogenous nature and complex structure; physical, chemical and petrographic, introduces two-fold complications during its combustion in power generation. Organic and inorganic constituents in various petrographic states alter chemically and physically. The products of coal combustion; unburned carbon, deposits, oxides of metals and non-metals, metal and non-metal complexes, need to be identified qualitatively and quantitatively to increase the coal combustion efficiency and to optimize the durability of power plant components.

This paper will describe the usage of various analytical tools like NMR, ESR, IR, Electron Microscopy, X-Ray, Fluorescent Microscopy coupled with Wet Analysis to analyze coal and its derivatives. Each spectroscopy will be related to a specific aspect of coal and its derivatives. The limiting conditions and the range of application of each of the tools will be provided. The knowledge of these ranges will help in monitoring accurate emission levels of a particulate concentration, NOx, SOx and will control several phenomena such as deposition, corrosion and erosion.
Correlation of Pneumatic Particle Erosion With the Micro-Mechanical Properties of a High Temperature Alloy
Authors: Moteff John , Rosa Eduardo
Published: April 2015

Although reasonable correlation may be obtained between the pneumatic particle erosion behavior of many metals and alloys with corresponding hardness measurements, this relationship does not necessarily agree at elevated test temperatures. It is shown that, for the case of a Ti-6A1-4V alloy, there is a significant difference when both the erosion and the hardness tests are conducted at temperatures above and below about one-half of the absolute melting temperature of this alloy. This circumstance, at the present time, is attributed to the change in the ductility of the alloy with test temperature. It is also shown that a measure of the strength and ductility may be obtained from the elevated temperature hardness measurements. A preliminary model relating the erosion rate with the strength and uniform elongation obtained through microhardness measurements is presented.
Numerical Simulation of Rotating Stall in Axial Compressor Blade Rows and Stages
Authors: Neuhoff H. G. , Grahl K. G.
Published: April 2015

Rotating stall is simulated by a time step integration procedure of the Euler equations. The prescribed compressors consist of finite inlet and outlet ducts, blade rows of finite chord lengths and a throttle without impedance. Due to this compressor model the net mass flow through the compressor remains constant during the transient to fully developed rotating stall. Results are presented for a highly loaded rotor and a transonic fan stage. Contrary to former nonlinear approaches, the presented theory indicates that the fully developed rotating stall in a single compressor rotor is not affected by the number of lobes of an initial circumferential disturbance. For a highly loaded stage the dependence of the stall parameters on the time constants of the cascade flow is demonstrated.
Experience With Offshore Gas Turbine Intake Filter Systems From a Practical Viewpoint
Authors: Shackell J.
Published: April 2015

Since the widespread adoption of gas turbines as the main power sources on offshore platforms throughout the world the special problems associated with the filtration of the air entering such engines have naturally received some attention.
NDT of Injection Molded Green and Sintered SiC Turbine Parts
Authors: Grellner W. , Schwetz K. A. , Lipp A.
Published: April 2015

Nondestructive evaluation of ceramic turbine components has to give special consideration to geometrical as well as to material requirements of these parts. Test procedures have to be able to detect all essential defects. As present X-ray penetration, especially the microfocus technique, is the most promising examination routine for special ceramics of complex shape.

Actual developments discussed, include the use of image intersifiers for real time monitoring and utilization of digital image processing to increase defect detectability, to decrease costs and to fabricate ceramic turbine parts of higher reliability.
An Approach to an Integrated Control System for a Modern Fighter Aircraft Engine
Authors: Lemmin Jürgen
Published: April 2015

In the field of today’s military aircraft engines, the engine control system consists in most cases of hydromechanical controls, as such, with an electronic supervisory system. This type of control makes the integration of engine and aircraft systems rather difficult. Even with the Tornado engine which features a full authority electronic engine controller, only initial steps in systems integration are realized.

With the introduction of digital electronics into both the engine control and the aircraft systems, together with the availability of data highway systems, large scale systems integration can be envisaged on future fighter aircraft, with the resultant improvement in overall weapon system performance.

This paper puts forward a proposal for a control concept for a reheated fighter engine, and outlines possibilities for integration with aircraft systems.
Characteristic Factors of a Compressor Rotor in Comparison With Two-Dimensional Cascade Data
Authors: Pfeil H. , Sieber J.
Published: April 2015

The performance of a blade in an axial-flow compressor rotor is compared with the performance in a two-dimensional cascade. Using a stationary hot-wire probe and a data processing system the velocity profiles across the rotor wakes were measured in order to calculate the profile losses and the lift coefficients of the rotor blade.
Effect of Boundary Layer Fences and Casing Treatment in a Centrifugal Impeller
Authors: Venkatrayulu N. , Raj D. Prithvi
Published: April 2015

The paper presents the results of experimental investigations carried out on an unshrouded impeller of a centrifugal compressor to explore the possibility of improving the exit flow condition by the use of boundary layer fences and casing treatment. Eight different locations of fences were tried on the impeller vanes and hub surface. The boundary layer fences placed on the vane suction surface resulted in improvement of the exit flow condition. A combination of grooves and the fences on the front casing cover near the inlet and tip of the impeller was also investigated.
Operating Efficiencies of a Lysholm, Helical Expander for Brayton-Cycle Heat Engines
Authors: Myers Blake , Deis Gary , Shell Tom
Published: April 2015

Operating tests on a Lysholm helical expander have been done to develop a data base for comparing the performance of helical expanders with turbine expanders by using simple scaling arguments. The eventual goal of such work would be to develop a rugged and reliable ceramic helical expander for operating at temperatures up to 1300°C (2400°F). We used a 127.5 mm (5.020 in.) metal expander on which we measured seven performance variables against applied pressure ratio at six shaft speeds and an inlet gas temperature of 100°C (212°F).

Our data system included: a torque and angular-speed cell to measure power; flow, pressure, and temperature instrumentation; and a data reduction program. Test results are presented in seven data plots; equations for computing the performance variables are tabulated.

Adiabatic efficiency was found to be at least 85% in the pressure ratio range of 2.75 to 5.00. Performance is strongly influenced by gas leakage. Large machines with clearance ratios the same as smaller machines would benefit by size scaling effects. We expect that ceramic helical expanders for 1300°C service would be able to operate at adiabatic efficiencies higher than 85%.
Effect of Area Ratio on the Performance of a 5.5:1 Pressure Ratio Centrifugal Impeller
Authors: Schumann Lawrence F. , Clark David A. , Wood Jerry R.
Published: April 2015

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was changed by successively cutting back the impeller exit axial width from an initial value of 7.57 mm to a final value of 5.97 mm. In all, four separate area ratios were tested. For each area ratio a series of impeller exit axial clearances was also tested. Test results are based on impeller exit surveys of total pressure, total temperature, and flow angle at a radius 1.115 times the impeller exit radius.

Results of the tests at design speed, peak efficiency, and an exit tip clearance of 8 percent of exit blade height show that the impeller equivalent pressure recovery coefficient peaked at a design point area ratio of approximately 2.748 while the impeller aerodynamic efficiency peaked at a lower value of area ratio of approximately 2.55. The variation of impeller efficiency with clearance showed expected trends with a loss of approximately 0.4 points in impeller efficiency for each percent increase in exit axial tip clearance for all impellers tested. The data also indicated that the impeller would probably separate at design area ratios greater than 2.748. An analysis was performed with a quasi-three-dimensional inviscid computer code which confirmed that a minimum velocity ratio was attained near this area ratio thus indicating separation. This data can be used to verify impeller flow models which attempt to account for very high diffusion and possible separation.
Numerical Investigation of Unsteady Subsonic Compressible Flows Through an Oscillating Cascade
Authors: Fransson T. H. , Pandolfi M.
Published: April 2015

A method for solving numerically the fully time-dependent two-dimensional Euler equations, applied to unsteady subsonic flow through vibrating turbomachine cascades with thin blades, is developed. The blades are assumed to vibrate at a constant interblade phase angle and the computed region is reduced to one blade passage, with the implementation of the interblade phase angle as a periodicity condition. The reliability of the method is validated by comparing it with an analytical flat plate theory, and the importance of radiative inlet and outlet boundary conditions for unsteady flow calculations is shown in an example.

The method can be used to compute the aerodynamic force and damping coefficients acting on the blades and to investigate the propagation of unsteady disturbances through a cascade in flutter conditions.
Durability and Damage Tolerance Assessment of the TF34-100 Engine
Authors: Ogg Jon S. , Reinhold Ronald R.
Published: April 2015

The critical nature of the TF34-100 engine to the Air Force’s A-10 Close Air Support weapon system made it important to obtain the best possible visibility of the engine’s future structural maintenance needs and component life limits. Accordingly, an in-depth structural durability and damage tolerance assessment was performed on this engine by a joint Air Force/General Electric team.

Results of the assessment team’s unprecedented analysis efforts culminated in a comprehensive Structural Maintenance Plan that identified both current and future maintenance actions necessary for insuring maximum flight safety. The plan entailed component inspection and replacement intervals, inspection systems, preferred modifications/reworks, and a life growth plan for extending the useful life of the TF34-100 upwards to 8000 A-10 mission hours.

This paper details the nature and extent of effort undertaken in conducting the 18 month structural assessment.
Field Evaluation and Operating Experience of the Allison 501-KB5 Industrial Gas Turbine
Authors: Latcovich John A. , Bach Charles S.
Published: April 2015

The Allison 501-KB5 3924 KW gas turbine was introduced to the industrial power generation market in 1982 as a low risk upgrade of the 501-KB engine. The aero-derivative and industrial background of the 501-KB engine is discussed along with the technical approach, engine features and performance (20% more power and 6% less fuel than the 501-KB) of the upgrade. The results of a one year field evaluation of an early 501-KB5 engine are presented, including performance testing and teardown inspections conducted after the evaluation. Since introduction in 1982, fifty-five production 501-KB5 engines have been delivered, and the operating experience of these engines, which now exceeds 230,000 hours is presented.
New Technology Uprating of Process Compressor and Generator Drive Gas Turbines
Authors: Allen R. P. , Smit H. C. M.
Published: April 2015

Investment in energy conservation projects can have substantial rates of return, particularly for companies like Dow Chemical which has many plants that are energy intensive. Dow also has many plants that rely on gas turbines for the bulk of their power generation. Thus improvements in efficiency of these gas turbines will contribute significantly to overall plant energy savings. This paper discusses how Dow uprated two of their gas turbines at their Netherlands complex, using retrofit packages developed by the General Electric Company. The justification, the field modifications, and the performance test results are all reviewed.
Transportable Gas Turbine Cogeneration Plant for German Coal Mine
Authors: Kowollik Gottfried , Ruhrkohle-Bergbau  , Heimer Heiko
Published: April 2015

This paper describes a pilot project at a German coal mine to utilize a transportable gas turbine cogeneration plant to produce electrical power and warm water.

Medium Btu gas with varying CH4 content is scavenged from several mines and will be used as a low cost waste fuel for the gas turbine. The mine currently requires substantial venting to control methane content in the shaft air.
Assessment of a Three-Dimensional Potential Code for Axial and Radial Blade Row Flows
Authors: Frühauf H.-H. , Krämer D. , Küster U.
Published: April 2015

An assessment of a three-dimensional potential code is presented for axial and radial blade row flows, for which experimental data or computational results are available. The prediction of a flow case with severe cross flow is included. Numerous 3-D potential flow effects will be discussed.

The conservative full potential equation for 3-D transonic flow is solved by a robust SLOR method. A new formulation of the downstream flow ensures the computability of blade row flows with arbitrary spanwise circulation distributions. Blade circulation distribution and downstream flow properties are obtained as a part of the solution. The surface representation in parameter form in the geometry definition program and the mesh generation program, as well as the tensor notation of the basic equation and a configuration-independent vortex sheet approximation prediction, ensure the computability of flows through blade rows with arbitrary complex geometries. The CRAY-1/M incore version of the code is inexpensive enough to be used in the aerodynamic design process of new blade rows with irrotational inflows.
Omar Hill-300 MW Cogeneration Plant for Enhanced Oil Recovery
Authors: Ondryas Igor S. , Myers Charles O. , Hauhe William E.
Published: April 2015

The paper describes a gas turbine based cogeneration plant producing a nominal 300 MWe and 1.8 MM lb/h (0.82 MM kg/h) of 80 percent quality steam for enhanced oil recovery. The plant, which has been in commercial operation since August 18, 1985 is located in the Kern River Oil Field near Bakersfield, California. The plant is owned by the Kern River Cogeneration Company. The paper describes the plant design philosophy as well as the major system operating parameters. The discussion of the overall project schedule highlights the major project milestones.
The Application of Active Magnetic Bearings to a Natural Gas Pipeline Compressor
Authors: Foster E. G. , Kulle V. , Peterson R. A.
Published: April 2015

The installation and operation of an active magnetic bearing in conjunction with a modified mechanical dry gas seal on a natural gas pipeline compressor is presented.

The emphasis of this paper is centered on the active magnetic bearing.

The active magnetic bearing was developed by Société de Mécanique Magnétique (S2M) of Vernon France. The first successful application to a natural gas pipeline compressor was a co-operative effort between NOVA, AN ALBERTA CORPORATION, S2M, and Magnetic Bearing Incorporated (MBI) of Radford, Virginia.

This paper represents a technical and economic assessment of the bearing, including installation and operational data.
A Decade of Experience With Model V-94 Gas Turbines
Authors: Deblon Bruno
Published: April 2015

The first Model V-94, the world’s largest single shaft gas turbine in operation, was placed in service more than ten years ago. To date the V-94 has been uprated to 141 MW ISO-baseload output and 20 units are in service. In addition a 60-cycle version has been derived on the basis of the latest V-94 experience. This paper describes the development, the various applications and the operating experiences with the V-94 gas turbines.
Power Increase of Gas Turbines by Inlet Air Pre-Cooling With Absorption Refrigeration Utilizing Exhaust Waste Heat
Authors: Malewski Werner F. , Holldorff Günther M.
Published: April 2015

Using heat energy from the tail-end of gas turbine exhaust, an ammonia absorption refrigeration system can precool the inlet air to a temperature slightly above the freezing point of the air humidity.

The concept is described and shows how it indicates a significant increase of gas turbine power output, depending on ambient conditions.
Full Load Development Testing of a 41MW Single Shaft Generator Drive Gas Turbine
Authors: O’Neill Simon T.
Published: April 2015

This paper describes the full load development testing of the CW251B10 gas turbine at the Westinghouse Canada gas turbine test facility in Hamilton, Ontario. The test instrumentation and data acquisition system are detailed together with the nature of the tests performed.
Heat Management in Advanced Aircraft Gas Turbine Engines
Authors: Brines Gerald L. , Gray David E.
Published: April 2015

This paper summarizes current and projected heat management techniques within aircraft gas turbines. Each of the primary heat sources is individually considered, including the thermodynamic cycle sources of fuel combustion and air compression, and the parasitic sources of friction, oil churning and rotor windage. For each source, the problem is presented, and solutions — both present and future — are offered. Heat management within low spool reduction gearing is also discussed because of the high probability of an advanced high speed turboprop and geared high bypass ratio turbofan propulsion system in the future.
Developments in New Gas Turbine Engine Demonstrator Programs
Authors: Johnson Edward T. , Klassen David D.
Published: April 2015

Since 1967 the Aviation Applied Technology Directorate (AATD) has sponsored four technology demonstrator engine programs. These programs have been established for purposes of verifying the engine technology level appropriate for the initiation of full scale engine development. While these were all highly successful, significant improvements have evolved in the approach to these programs. This paper discusses this evolution, lessons learned, and results.
The CW251 B10 Gas Turbine Engine
Authors: Kuly P. W.
Published: April 2015

The CW251B10 gas turbine engine, rated at 41.2 MW ISO, is designed for utility and industrial power generation. Design objectives were; high efficiency, high reliability, and ease of site maintenance. This paper reviews the unit performance capability, describes in detail the mechanical design of the engine and reviews its maintenance features.
Acid Corrosion in a CAES Recuperator
Authors: Lukas Holger , Mehta Bhupen
Published: April 2015

Cold end corrosion and deposit formation due to sulfuric acid is a phenomenon not uncommon in boilers and waste heat boilers. Normally, the operating conditions can be changed to reduce or eliminate the corrosion and deposition problem. In a Compressed Air Energy Storage (CAES) recuperator, changing the operating conditions is not a practical solution. This paper presents the results of three different test periods using various materials at different operating temperatures.
The Development of a Multi-Stage Heavy-Duty Transonic Compressor for Industrial Gas Turbines
Authors: Farkas F.
Published: April 2015

The decision was made to use a heavy-duty, 12-stage transonic compressor for the new Type 8 Brown Boveri gas turbine.

With this advanced concept, it became possible both to increase the pressure ratio to 16:1 and to reduce the number of stages by half. The wide-chord, low aspect-ratio blade design brought about a further decrease in the total number of components and a reduction of the mechanical stresses. A variable inlet guide vane was added to provide flexibility in combined cycle operation.

Appropriate computer-assisted design systems were developed for evaluation of design and off-design aerodynamics.

As a back-up for the design work, tests were run on several model compressors to explore and study aerodynamic and mechanical behavior. Detailed field measurements were also taken on the prototype units of the Type 8 as a final check to confirm the expected values.
Thermal Stability Concerns of Navy Aviation Fuel
Authors: Moses C. A. , Shayeson M. W. , Karpovich P. A.
Published: April 2015

The U.S. Navy’s concerns about the thermal stability of aviation fuel stem from a combination of increased performance requirements of engines and potential degradation in fuel quality. The results of recent atomizer fouling tests with hot fuel are presented. These are combined with similar results from Air Force programs and analyzed with respect to the impact on engine performance and reliability.
Electron beam collimation from an all-metal double-gate 40 000 nanotip array: Improved emission current and beam uniformity upon neon gas conditioning
Authors: Das Kanungo Pratyush , Helfenstein Patrick , Guzenko Vitaliy , Lee Chiwon , Paraliev Martin , Tsujino Soichiro
Published: April 2015

In this study, the authors characterized field emission for stacked-double-gate all-metal field emitter arrays (FEAs) consisting of 40 000 nanotips. After careful conditioning of the FEAs under ultrahigh vacuum and in low-pressure neon gas ambient, the authors were able to produce a highly collimated beam with a current of ∼50 μA which showed an improved beam homogeneity. The beam rms radius reduced by a factor 10 and the transverse energy spread was reduced to well below 1 eV.
Taoist Tai Chi® and Memory Intervention for Individuals with Mild Cognitive Impairment
Authors: Fogarty Jennifer N. , Murphy Kelly J. , McFarlane Bruce , Montero-Odasso Manuel , Wells Jennie , Troyer Angela K. , Trinh Daniel , Gutmanis Iris , Hansen Kevin T.
Published: April 2015

Objective:

It was hypothesized that a combined Taoist Tai Chi (TTC) and a memory intervention program (MIP) would be superior to a MIP alone in improving everyday memory behaviors in individuals with amnestic mild cognitive impairment (aMCI). A secondary hypothesis was that TTC would improve cognition, self-reported health status, gait, and balance.

Method:

A total of 48 individuals were randomly assigned to take part in MIP + TTC or MIP alone. The TTC intervention consisted of twenty 90 min sessions. Outcome measures were given at baseline, and after 10 and 22 weeks.

Results:

Both groups significantly increased their memory strategy knowledge and use, ratings of physical health, processing speed, everyday memory, and visual attention. No preferential benefit was found for individuals in the MIP + TTC group on cognition, gait, or balance measures.

Conclusions:

Contrary to expectations, TTC exercise did not specifically improve cognition or physical mobility. Explanations for null findings are explored.
Critics question plans to spray dispersant in future deep spills
Authors: Cornwall Warren
Published: April 2015

Deep-sea use of oil spill dispersants questioned.
Suppression of endogenous gene silencing by bidirectional cytoplasmic RNA decay in
Arabidopsis
Authors: Zhang Xinyan , Zhu Ying , Liu Xiaodan , Hong Xinyu , Xu Yang , Zhu Ping , Shen Yang , Wu Huihui , Ji Yusi , Wen Xing , Zhang Chen , Zhao Qiong , Wang Yichuan , Lu Jian , Guo Hongwei
Published: April 2015

Protecting against runaway defense systems

RNA interference defends cells against invading genetic elements, such as viruses or transgenes. But while the invasive RNAs are under attack, what protects the normal endogenous RNAs? Zhang
et al.
identified, in the small plant
Arabidopsis
, a surveillance system to do just that: Preserve the normal transcriptome and keep the attack focused on invasive transcripts.

Science
, this issue p.
120
Tracking antiwear film formation
Authors: Schwarz Udo D.
Published: April 2015

Atomic force microscopy visualizes the formation of a lubricating film

[Also see Report by

Gosvami
et al.

]
Adoptive cell transfer as personalized immunotherapy for human cancer
Authors: Rosenberg Steven A. , Restifo Nicholas P.
Published: April 2015

Adoptive cell therapy (ACT) is a highly personalized cancer therapy that involves administration to the cancer-bearing host of immune cells with direct anticancer activity. ACT using naturally occurring tumor-reactive lymphocytes has mediated durable, complete regressions in patients with melanoma, probably by targeting somatic mutations exclusive to each cancer. These results have expanded the reach of ACT to the treatment of common epithelial cancers. In addition, the ability to genetically engineer lymphocytes to express conventional T cell receptors or chimeric antigen receptors has further extended the successful application of ACT for cancer treatment.
The future of immune checkpoint therapy
Authors: Sharma Padmanee , Allison James P.
Published: April 2015

Immune checkpoint therapy, which targets regulatory pathways in T cells to enhance antitumor immune responses, has led to important clinical advances and provided a new weapon against cancer. This therapy has elicited durable clinical responses and, in a fraction of patients, long-term remissions where patients exhibit no clinical signs of cancer for many years. The way forward for this class of novel agents lies in our ability to understand human immune responses in the tumor microenvironment. This will provide valuable information regarding the dynamic nature of the immune response and regulation of additional pathways that will need to be targeted through combination therapies to provide survival benefit for greater numbers of patients.
The guardian of the genome
p53 The Gene That Cracked the Cancer Code
Sue Armstrong
Bloomsbury Sigma, 2015. 287 pp.
Authors: Mandinova Anna , Lee Sam W.
Published: April 2015

Inside the quest to characterize the role of p53 in cancer
How young stars grow and become focused
Authors: Hoare M. G.
Published: April 2015

Observations 18 years apart capture early changes of a massive star

[Also see Report by

Carrasco-González
et al.

]
Objectified
Cornelia Parker
Mary Grif ths, Curator
The Whitworth, Manchester, UK 14 February 2015 to 31 May 2015
Authors: Dixon Deborah
Published: April 2015

An artist's approach to materials science
A community for disaster science
Authors: McNutt Marcia
Published: April 2015

During disasters such as the 2010 Deepwater Horizon oil spill, engaging the expertise of the academic community helped responders make critical decisions. A major barrier to such engagement, however, is the cultural gap between academia's reward system and that which prevails in the disaster response community. Given the importance of developing smart approaches to disasters, whether natural or human-caused, we need to bridge this gap.
Protective Efficacy of the Conserved NP, PB1, and M1 Proteins as Immunogens in DNA- and Vaccinia Virus-Based Universal Influenza A Virus Vaccines in Mice
Authors: Wang Wenling , Li Renqing , Deng Yao , Lu Ning , Chen Hong , Meng Xin , Wang Wen , Wang Xiuping , Yan Kexia , Qi Xiangrong , Zhang Xiangmin , Xin Wei , Lu Zhenhua , Li Xueren , Bian Tao , Gao Yingying , Tan Wenjie , Ruan Li
Published: April 2015

The conventional hemagglutinin (HA)- and neuraminidase (NA)-based influenza vaccines need to be updated most years and are ineffective if the glycoprotein HA of the vaccine strains is a mismatch with that of the epidemic strain. Universal vaccines targeting conserved viral components might provide cross-protection and thus complement and improve conventional vaccines. In this study, we generated DNA plasmids and recombinant vaccinia viruses expressing the conserved proteins nucleoprotein (NP), polymerase basic 1 (PB1), and matrix 1 (M1) from influenza virus strain A/Beijing/30/95 (H3N2). BALB/c mice were immunized intramuscularly with a single vaccine based on NP, PB1, or M1 alone or a combination vaccine based on all three antigens and were then challenged with lethal doses of the heterologous influenza virus strain A/PR/8/34 (H1N1). Vaccines based on NP, PB1, and M1 provided complete or partial protection against challenge with 1.7 50% lethal dose (LD
50
) of PR8 in mice. Of the three antigens, NP-based vaccines induced protection against 5 LD
50
and 10 LD
50
and thus exhibited the greatest protective effect. Universal influenza vaccines based on the combination of NP, PB1, and M1 induced a strong immune response and thus might be an alternative approach to addressing future influenza virus pandemics.
Continual Reintroduction of Human Pandemic H1N1 Influenza A Viruses into Swine in the United States, 2009 to 2014
Authors: Nelson Martha I. , Stratton Jered , Killian Mary Lea , Janas-Martindale Alicia , Vincent Amy L.
Published: April 2015

The diversity of influenza A viruses in swine (swIAVs) presents an important pandemic threat. Knowledge of the human-swine interface is particularly important for understanding how viruses with pandemic potential evolve in swine hosts. Through phylogenetic analysis of contemporary swIAVs in the United States, we demonstrate that human-to-swine transmission of pandemic H1N1 (pH1N1) viruses has occurred continuously in the years following the 2009 H1N1 pandemic and has been an important contributor to the genetic diversity of U.S. swIAVs. Although pandemic H1 and N1 segments had been largely removed from the U.S. swine population by 2013 via reassortment with other swIAVs, these antigens reemerged following multiple human-to-swine transmission events during the 2013-2014 seasonal epidemic. These findings indicate that the six internal gene segments from pH1N1 viruses are likely to be sustained long term in the U.S. swine population, with periodic reemergence of pandemic hemagglutinin (HA) and neuraminidase (NA) segments in association with seasonal pH1N1 epidemics in humans. Vaccinating U.S. swine workers may reduce infection of both humans and swine and in turn limit the role of humans as sources of influenza virus diversity in pigs.

IMPORTANCE
Swine are important hosts in the evolution of influenza A viruses with pandemic potential. Here, we analyze influenza virus sequence data generated by the U.S. Department of Agriculture's national surveillance system to identify the central role of humans in the reemergence of pandemic H1N1 (pH1N1) influenza viruses in U.S. swine herds in 2014. These findings emphasize the important role of humans as continuous sources of influenza virus diversity in swine and indicate that influenza viruses with pandemic HA and NA segments are likely to continue to reemerge in U.S. swine in association with seasonal pH1N1 epidemics in humans.
Interregional Coevolution Analysis Revealing Functional and Structural Interrelatedness between Different Genomic Regions in
Human Mastadenovirus D
Authors: Gonzalez Gabriel , Koyanagi Kanako O. , Aoki Koki , Watanabe Hidemi
Published: April 2015

Human mastadenovirus D
(HAdV-D) is exceptionally rich in type among the seven human adenovirus species. This feature is attributed to frequent intertypic recombination events that have reshuffled orthologous genomic regions between different HAdV-D types. However, this trend appears to be paradoxical, as it has been demonstrated that the replacement of some of the interacting proteins for a specific function with other orthologues causes malfunction, indicating that intertypic recombination events may be deleterious. In order to understand why the paradoxical trend has been possible in HAdV-D evolution, we conducted an interregional coevolution analysis between different genomic regions of 45 different HAdV-D types and found that ca. 70% of the genome has coevolved, even though these are fragmented into several pieces via short intertypic recombination hot spot regions. Since it is statistically and biologically unlikely that all of the coevolving fragments have synchronously recombined between different genomes, it is probable that these regions have stayed in their original genomes during evolution as a platform for frequent intertypic recombination events in limited regions. It is also unlikely that the same genomic regions have remained almost untouched during frequent recombination events, independently, in all different types, by chance. In addition, the coevolving regions contain the coding regions of physically interacting proteins for important functions. Therefore, the coevolution of these regions should be attributed at least in part to natural selection due to common biological constraints operating on all types, including protein-protein interactions for essential functions. Our results predict additional unknown protein interactions.

IMPORTANCE
Human mastadenovirus D
, an exceptionally type-rich human adenovirus species and causative agent of different diseases in a wide variety of tissues, including that of ocular region and digestive tract, as well as an opportunistic infection in immunocompromised patients, is known to have highly diverged through frequent intertypic recombination events; however, it has also been demonstrated that the replacement of a component protein of a multiprotein system with a homologous protein causes malfunction. The present study solved this apparent paradox by looking at which genomic parts have coevolved using a newly developed method. The results revealed that intertypic recombination events have occurred in limited genomic regions and been avoided in the genomic regions encoding proteins that physically interact for a given function. This approach detects purifying selection against recombination events causing the replacement of partial components of multiprotein systems and therefore predicts physical and functional interactions between different proteins and/or genomic elements.
Artificial Recruitment of UAF1-USP Complexes by a PHLPP1-E1 Chimeric Helicase Enhances Human Papillomavirus DNA Replication
Authors: Gagnon David , Lehoux Michaël , Archambault Jacques
Published: April 2015

The E1 helicase from anogenital human papillomavirus (HPV) types interacts with the cellular WD repeat-containing protein UAF1 in complex with the deubiquitinating enzyme USP1, USP12, or USP46. This interaction stimulates viral DNA replication and is required for maintenance of the viral episome in keratinocytes. E1 associates with UAF1 through a short UAF1-binding site (UBS) located within the N-terminal 40 residues of the protein. Here, we investigated if the E1 UBS could be replaced by the analogous domain from an unrelated protein, the pleckstrin homology domain and leucine-rich repeat protein phosphatase 1 (PHLPP1). We found that PHLPP1 and E1 interact with UAF1 in a mutually exclusive manner and mapped the minimal PHLPP1 UBS (PUBS) to a 100-amino-acid region sufficient for assembly into UAF1-USP complexes. Similarly to the E1 UBS, overexpression of PUBS in
trans
inhibited HPV DNA replication, albeit less efficiently. Characterization of a PHLPP1-E1 chimeric helicase revealed that PUBS could partially substitute for the E1 UBS in enhancing viral DNA replication and that the stimulatory effect of PUBS likely involves recruitment of UAF1-USP complexes, as it was abolished by mutations that weaken UAF1-binding and by overexpression of catalytically inactive USPs. Although functionally similar to the E1 UBS, PUBS is larger in size and requires both the WD repeat region and C-terminal ubiquitin-like domain of UAF1 for interaction, in contrast to E1, which does not contact the latter. Overall, this comparison of two heterologous UBSs indicates that these domains function as transferable protein interaction modules and provide further evidence that the association of E1 with UAF1-containing deubiquitinating complexes stimulates HPV DNA replication.

IMPORTANCE
The E1 protein from anogenital HPV types interacts with the UAF1-associated deubiquitinating enzymes USP1, USP12, and USP46 to stimulate replication of the viral genome. Little is known about the molecular nature of the E1-UAF1 interaction and, more generally, how UAF1-USP complexes recognize their substrate proteins. To address this question, we characterized the UAF1-binding site (UBS) of PHLPP1, a protein unrelated to E1. Using a PHLPP1-E1 chimeric helicase, we show that the PHLPP1 UBS (PUBS) can partially substitute for the E1 UBS in stimulating HPV DNA replication. This stimulation required conserved sequences in PUBS that meditate its interaction with UAF1, including a motif common to the E1 UBS. These results indicate that UAF1-binding sequences function as transferable protein interaction modules and provide further evidence that UAF1-USP complexes stimulate HPV DNA replication.