bluuebunny/crossref_metadata_2025_split huggingface dataset:
The alpha1,3GalT knockout/alpha1,2FucT transgenic pig does not appear to have an advantage over the alpha1,3GalT knockout pig with respect to glycolipid reactivity with human serum antibodies
Authors: Diswall Mette , Benktander John , Ångström Jonas , Teneberg Susann , Breimer Michael E. 
Published: November 2013

AbstractBackgroundThe human H‐transferase (α2FucT) was introduced in Gal‐negative pigs to produce pig organs not only free from Gal‐antigens, but also in which the uncapped N‐acetyllactosamine precursor had been transformed into non‐xenogenic blood group H type 2 compounds. This work is the first descriptive analysis of glycolipids from the GalT‐KO/FucT‐TG pig. The aim was to investigate the cell membrane antigens in GalT‐KO/FucT‐TG tissues to explore its efficacy as an organ donor. Also, detailed knowledge on the correlation between the cellular glycosyltransferase configuration and the resulting carbohydrate phenotype expression is valuable from a basic glycobiological perspective.MethodsNeutral and acidic glycolipids from GalT‐KO/FucT‐TG small intestine were compared with glycolipids from two wildtype and two GalT‐KO pig intestines. Glycolipid reactivity was tested on thin layer chromatography plates using chemical reagents, antibodies, lectins, and human serum. Structural characterization of neutral glycolipids was performed by LC‐ESI/MS and proton NMR spectroscopy.ResultsCharacterization of the glycolipid expression in GalT‐KO/FucT‐TG intestine showed absence of Gal antigens and decreased/unchanged levels of the N‐acetyllactosamine precursor and the blood group H type 2 expression, when compared with the wildtype. The reactivity of human serum antibodies to GalT‐KO/FucT‐TG derived glycolipids was similar or slightly elevated when compared with GalT‐KO glycolipids. Results from LC‐ESI/MS and proton NMR spectroscopy revealed no established neutral xenogenic antigens in the GalT‐KO/FucT‐TG pig, and could thus not explain the immunologic reactivity to human serum antibodies. The antibody binding to acidic glycolipids is most likely to be explained by the abundance of N‐glycolylneuraminic acid epitopes in pig tissues. Six neutral complex biantennary glycolipids with blood group H type 1, 2, Lewisx and Lewisy determinants were found, of which three were identified in this work for the first time. One of these was a nonaglycosylceramide with blood group H type 2 and lactosyl determinants linked to a lactotetraosyl core, and the other two were decaglycosylceramides with blood group H type 1 and H type 2 determinants linked to a neolactotetraosyl core, and Lewisx and blood group H type 1 determinants on a lactotetraosyl core, respectively.ConclusionsLipid‐linked carbohydrate antigens in the GalT‐KO/FucT‐TG pig intestine showed no or minor qualitative difference when compared with GalT‐KO pigs. The GalT‐KO/FucT‐TG pig did not appear to have an advantage over the GalT‐KO pig with respect to reactivity with human antibodies from a xenotransplantation perspective.
The Evidentiary Value of Challenge Trials for Three Pre‐harvest Food Safety Topics: A Systematic Assessment
Authors: Wisener L. V. , Sargeant J. M. , O'Connor A. M. , Faires M. C. , Glass‐Kaastra S. K. 
Published: November 2013

SummaryReducing zoonotic pathogens in food animals prior to harvest will reduce the pathogen burden that enters the food chain and the environment. Consequently, the burden of enteric illness in humans may be reduced. Evaluating interventions to reduce a pathogen in animals often begins with challenge trials, in which animals are deliberately exposed to the pathogen under controlled conditions. Challenge trials are subsequently followed by field trials, also known as randomized controlled trials, in which the animals are naturally exposed to the pathogen. Challenge trials can most effectively inform field trials only if they precede field trials, are robust, internally valid and transparently reported. Using systematic review and meta‐analysis methodology, we examined the pre‐harvest food safety literature for three intervention—pathogen—species combinations: probiotics/competitive exclusion products in ruminants to reduceEscherichia coliO157 shedding, vaccines in ruminants to reduceE. coliO157 shedding and vaccines in swine to reduceSalmonellashedding. We examined two outcomes, prevalence of faecal shedding at the end of the trial and prevalence of faecal shedding throughout the trial period, to compare challenge trials and field trials. We found that challenge trials occurred concurrently with field trials, challenge trials suffered from reporting deficiencies of methodological features, challenge trials tended to report a more favourable outcome than field trials, and there was some evidence of publication bias among all three intervention–pathogen–species combinations. Challenge trials would better serve to inform field trials if they precede field trials, are methodologically sound, include transparent reporting and are published regardless of their results. In addition, due to our findings of greater efficacy reported among challenge trials compared with field trials, risk models predicting the public health benefits of pre‐harvest interventions to reduce zoonotic pathogens in livestock might be best served by field trial results alone.
A Compact Diffuser and Scroll for a Centrifugal Compressor
Authors: Rodgers Colin , Brown Daniel , Thompson Robert 
Published: November 2013

This paper describes the test development of a compact diverging sidewall spiral diffuser for a small gas turbine auxiliary power units (APU’s) of conventional load compressor type wherein the gas generator or core module directly drives a separate centrifugal load compressor to supply a combination of both compressor air for main engine starting and air conditioning, together with shaft power to drive an engine mounted electric generator.
The APU capability to efficiently supply both pneumatic and electrical power demands a load compressor with a wide flow range at rated speed and low resisting torque during start which is achieved with modulated variable inlet guide vanes (IGV’s).
The compressor vaned diffuser design was unlike most conventional channel diffusers in that the diffusing passage downstream of the throat had diverging sidewalls to diffuse the flow radial component prior to discharge into the delivery scroll.
Test evaluation of this diffuser was conducted on a specially designed turbodrive compressor rig at pressure ratios up to 5:1 and rotational speeds up to 65000 rpm. Test results showed that the design performance requirements were satisfied.
The uniqueness of the design later prompted a CFD diagnosis of the compressor as a code verification case the computational results of which are presented in comparison to the experimental data.
A Study on Optimal Design of Filament Winding Composite Tower for 2 MW Class Horizontal Axis Wind Turbine Systems
Authors: Kong Changduk , Lim Sungjin , Park Hyunbum 
Published: November 2013

Although the tower of the horizontal axis wind turbine system is a simple structure relatively to the wind turbine rotor system, its production cost tower is about 20–25% of the whole wind turbine system cost. If a composite materials tower is used instead of the existing steel tower, the production cost can be reduced due to use of low cost composite materials, simple manufacturing process, easy transportation and easy assembly. However studies on the composite materials towers are very few.
Therefore, in this study a specific structural design procedure for 2 MW class glass/polyester face sheets-sand/ polyester core sandwich composite wind turbine system towers is newly proposed through load case study, trade-off study, optimal structural design and structural analysis. Optimal tower design can minimize both weight and cost. In the structural design of the tower, three kinds of loads such as wind load, blades, nacelle and tower weight and blade aerodynamic drag load should be considered. Initial structural design is carried out using the netting rule and the rule of mixture. Then the structural safety and stability are confirmed using a commercial finite element code, MSC NASTRAN/PATRAN. It is confirmed that the finally proposed tower meets the tower design requirements.
Three-Dimensional Model for Manufacturing and Inspection
Authors: Pippenger Brian S. 
Published: November 2013

Three-dimensional Model-Based Engineering (MBE) along with Quality Information Framework (QIF) is an approach to product design, manufacturing, and support where a digital three-dimensional representation of the product serves as the normative source for information communicated throughout the product’s lifecycle and supply chain. MBE simplifies data management and provides a more powerful communication medium than 2D-based environments. This is not just using a model for reference or a visual aid. The model will be the definition for the parts being manufactured, inspected, and built into full engines. The use of two-dimensional prints will be outdated and a culture change will be needed to embrace this change. Many organizations are implementing MBE and are using this technology to produce aerospace products. Manufacturing and inspection functions are dependent on the models from cradle to grave of the product lifecycle. These smart models will have all of the necessary dimensional metrology interoperability, GD&T encoded and product manufacturing information (PMI) data all in a standardized format associated within the model. This will allow for a model that has less errors, more functionality with manufacturing and inspection systems. The information included in the Model Based Definition (MBD) will be part of the QIF.
The QIF fully defines quality measurement plans, measurement results, measurement rules, measurement resources, and results analysis. This combined with the PMI for manufacturing will provide a comprehensive MBD that can be used for all of the manufacturing process in the lifecycle of the product.
The culture will need to progress from two-dimensional paper prints to smart three-dimensional models that are rich with data. These models will drive the process and be the final word for part acceptance; paper prints will not be needed or produced. These types of models will drive almost all of the military’s new designs and if the organization is not prepared for this change, it will lose many opportunities to be competitive.
Static Destabilizing Behavior for Gas Annular Seals at High Eccentricity Ratios
Authors: Childs Dara W. , Arthur Stephen P. 
Published: November 2013

The centering force of a plain, annular, liquid seal in a centered position has a pronounced effect on the rotordynamic behavior of pumps due to the Lomakin Effect. In centrifugal injection compressors, the centering force for a hole-pattern-stator/smooth-rotor for a balance-piston seal in a straight-through design or a division-wall seal in a back-to-back design has an impact on the rotordynamic behavior of high-pressure injection compressors. Annular seals for pumps and compressors are designed to operate in a nominally centered position. Previous test results show that the direct (centering) stiffness for liquid seals and hole-pattern-stator seals remain relatively constant out to eccentricity ratios of 0.5. For liquid seals, tests have shown positive centering capability at eccentricity ratios on the order of 0.7.
New test results are presented for annular gas seals with smooth and hole-pattern stators, moving from centered to fully eccentric (contact) positions. The test fluid is air. The tests are for non-rotating conditions with a supply pressure up to 70 bars and pressure rations (PRs) of 0.4, 0.5, and 0.6. The exit Mach numbers for the tests are on the order of 0.33, so compressibility effects are not pronounced.
Test results are presented for the net reaction force for a smooth seal and a hole-pattern-stator gas annular seal in moving from centered to fully eccentric positions. Comparisons are made between measurements and predictions from a bulk-flow code.
The smooth seal creates significantly larger de-centering forces than the HP seal. Its measured de-centering force increases steadily as the stator approaches the wall. The negative slope of the reaction force also increases, indicating a steadily increasing negative stiffness. The de-centering force increased with decreasing PR, increasing ΔP, and is much larger than predicted.
The HP seal de-centering reaction force is bi-linear with an approximate constant slope out to ε0 ≅ 0.5, and then a much steeper slope out to wall contact. The model does not predict the bilinear behavior but does a reasonable job of predicting the force magnitude at contact.
The de-centering forces measured here have not previously been reported and emphasize the importance of concentric assembly of annular seals in pumps and compressors. Unanticipated eccentricities that create negative stiffness will lead to over prediction of critical speeds and overly optimistic stability calculations.
Multidisciplinary Automated Optimization Strategy on a Counter Rotating Fan
Authors: Aulich Anne-Laure , Goerke Daniel , Blocher Michael , Nicke Eberhard , Kocian Frank 
Published: November 2013

Multidisciplinary automated optimization processes are nowadays essential to obtain optimal turbomachinery components. However, an extremely large number of free variables, constraints and objectives results in a complex task. This paper presents an optimization strategy developed to handle with different constraints, design goals concerning aerodynamic, mechanic and aeroelastic, and finally manufacturing aspects. This strategy has been applied to a counter rotating integrated shrouded propfan, which is developed within a DLR-project. Both rotors have been already aerodynamic optimized in a first design phase coupled with a mechanical analysis of the CF/PEEK blades with titanium clevises. Detailed analysis showed high displacements and unreliable Campbell-Diagrams. To reach a rig-ready design a new optimization strategy has been developed.
The optimizations feature more than hundred free variables, two objective functions, as well as a high number of aerodynamic and mechanical constraints. The mechanical behavior of the blades has been improved step by step in four successive aeromechanical optimizations. To secure the improvement obtained in one optimization, their objective functions become constraints in the next step. In the first optimization, the efforts have been focused on reducing the maximal absolute displacements in several operation points. In the second one, the scattering of the maximal absolute displacements between several operation points have been reduced. In the third optimization, the Campbell-Diagrams have been additionally optimized. Although the aerodynamic performance remained on a good level, it decreased a little bit in this design phase. For this reason, an additional fourth optimization was performed with the objective to increase the fan efficiency by keeping the good mechanical behavior reached before.
The presented optimization strategy has been successfully completed and the best members obtained show an almost satisfactory mechanical feasibility in view of the planned rig test.
Measurements Versus Predictions for the Static and Dynamic Characteristics of a Four-Pad, Rocker-Pivot, Tilting-Pad Journal Bearing
Authors: Tschoepe David P. , Childs Dara W. 
Published: November 2013

Measured and predicted static and dynamic characteristics are provided for a four-pad, rocker-pivot, tilting-pad journal bearing in the load-on-pad and load-between-pad orientations. The bearing has the following characteristics: 4 pads, .57 pad pivot offset, 0.6 L/D ratio, 60.33 mm (2.375in) pad axial length, 0.08255 mm (0.00325 in) radial clearance in the load-on-pad orientation, and 0.1189 mm (0.00468 in) radial clearance in the load-between-pad orientation. Tests were conducted on a floating test bearing design with unit loads ranging from 0 to 2903 kPa (421.1 psi) and speeds from 6.8 to 13.2 krpm.
For all rotor speeds, hot-clearance measurements were taken to show the reduction in bearing clearance due to thermal expansion of the shaft and pads during testing. As the testing conditions get hotter, the rotor, pads, and bearing expand, decreasing radial bearing clearance. Hot-clearance measurements showed a 16–25% decrease in clearance compared to a clearance measurement at room temperature. To look at the radial thermal gradient in the loaded pad, embedded thermocouples were inserted inside the bearing pad near the bearing housing. Results showed a 5–25°C decrease in temperature from the rotor side of the pad to the temperatures near the bearing housing. This radial temperature gradient caused an uneven thermal deflection in the pad, changing the pads’ radii of curvature.
For all test conditions, dynamic tests were performed over a range of excitation frequencies to obtain complex dynamic stiffness coefficients as a function of frequency. The direct real dynamic stiffness coefficients were then fitted with a quadratic function with respect to frequency. From the curve fit, the frequency dependence was captured by including a virtual-mass matrix [M] to produce a frequency independent [K][C][M] model.
The direct dynamic stiffness coefficients for the load-on-pad orientation showed significant orthotropy, while the load-between-pad did not. The load-between-pad showed slight orthotropy as load increased. Experimental cross-coupled stiffness coefficients were measured in both load orientations, but were of the same sign and significantly less than direct stiffness coefficients.
In both orientations the imaginary part of the measured dynamic stiffness increased linearly with increasing frequency, allowing for frequency-independent direct damping coefficients.
Rotordynamic coefficients presented were compared to predictions from two Reynolds-based models. The models showed the importance of taking into account pivot contact flexibility and different pad geometries (due to the reduction in bearing clearance during testing) in predicting rotordynamic coefficients. If either of these two inputs were incorrect, then predictions for the bearings impedance coefficients were very inaccurate.
Investigation of Wake Induced Transition in Low-Pressure Turbines Using Large Eddy Simulation
Authors: Nagabhushana Rao V. , Tucker P. G. , Jefferson-Loveday R. J. , Coull J. D. 
Published: November 2013

Modern ‘high-lift’ blade designs incorporated into the low pressure turbine (LPT) of aero-engines typically exhibit a separation bubble on the suction surface of the airfoil. The size of the bubble and the loss it generates is governed by the transition process in the separated shear layer. However, the wakes shed by the upstream blade rows, the turbulent fluctuations in the free-stream and the roughness over the blade complicates the transition process.
The current paper numerically investigates the transition of a separated shear layer over a flat plate with an elliptic leading edge using large eddy simulations (LES). The upper wall of the test section is inviscid and specifically contoured to impose a streamwise pressure distribution over the flat plate to simulate the suction surface of a LPT blade. The influences of free-stream turbulence (FST), periodic wake passing and streamwise pressure distribution (blade loading) are considered.
The simulations were carried out at a Reynolds number of 83,000 based on the length of the flat plate (S0 = 0.5m) and the velocity at the nominal trailing edge (UTE ∼ 2.55 m/s). A high turbulence intensity of 4% and a dimensionless wake passing frequency (fr = fwakeS0/UTE, where fwake is the dimensional wake frequency) of 0.84 is chosen for the study. Two different distributions representative of a ‘high-lift’ and an ‘ultra-high-lift’ turbine blade are examined. An in-house, high order, flow solver is used for the Large Eddy Simulations (LES). The Variational Multi-scale approach is used to account for the sub-grid scale stresses.
Results obtained from the current LES compare favorably with the extensive experimental data previously obtained for the test cases considered. The LES results are then used to further explore the flow physics involved in the transition process, in particular the role of Klebanoff streaks and their influence on performance. The additional effect of surface roughness of the blade has also been studied for one of the blade loadings. The benefit that roughness can offer for highly loaded turbine blades is demonstrated.
Investigation of Rotor-Casing Interactions in the Centrifugal Compressor of a Helicopter Engine
Authors: Meingast Markus B. , Batailly Alain , Legrand Mathias , Ousty Jean-Philippe 
Published: November 2013

The phenomenology of rotor-casing setups experiencing contact interactions is still poorly understood, particularly when complex geometries such as centrifugal compressors are involved. Although interaction phenomena have been witnessed and recorded during industrial experiments, the physical understanding of what occurs during these interactions is limited. The usual design approach is to consider possible modal interaction points in a linear framework and move these outside of normal operating conditions by means of minor geometric changes. Based on this linear approach, no information on the severity of these interactions is available to the designer. Besides, a possible interaction point appearing in the linear framework may not produce any harmful interactions, thereby increasing design restrictions.
Based on an in-house numerical strategy previously presented, contact interactions for a flexible centrifugal compressor from a helicopter engine and rigid casing setup are investigated. By imposing a small deformation on the casing geometry, blade/casing contact is initiated and subsequent interactions feature complex phenomena that are analyzed. In comparison to previous interaction simulations involving axial compressors, a higher degree of complexity of the numerical simulations stems from a strong curvature of the blade and very significant blade-disk coupling. This coupling presents itself towards the trailing edge where compressor mode shapes indicate a significant component normal to the casing surface. Accordingly, these modes may lead to large amplitude contact forces.
Time simulation results are confronted with experimental observations, and the consistency of the behavior of the numerical model with respect to industrial observations is underlined. A frequency domain post-processing of the results reveals specific engine order interactions and frequency spectra are plotted in order to interpret the phenomenon of interest. Such methodology will enable designers to more efficiently discriminate potential critical interaction speeds as compared to the classical linear frequency approach.
Creep and Fatigue of Single Crystal and Directionally Solidified Nickel-Base Blades via a Unified Approach Based on Hill48 Potential Function: Part 1 — Plasticity and Creep
Authors: Ramaglia Alessandro D. , Villari Paolo 
Published: November 2013

A simple phenomenological approach is devised based on the formalism introduced by Hill’s work on plasticity which allows for a unified description of the plastic-creep and fatigue responses of Single Crystal (SX) and Directionally Solidified (DS) nickel-base blades used in heavy duty gas turbines. To this end, the mechanical behavior of real SX and DS materials is approximated by adopting simplified classes of anisotropy able to reproduce the most relevant features of their material response. The hypotheses behind such choice depend from one side on a precise balance of various sources of uncertainties in both design analyses and experimental data and from the other side help in guaranteeing the respect of constraints on robustness, availability and maintainability of the design practice.
In this first part the modeling of plasticity and creep is discussed and accompanied by FEM analyses of real components. The set of tools presented here will be completed in the second part of this work where fatigue will be investigated.