bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Investigation of the Flow in an Aft-Swept Transonic Compressor Rotor
Authors: Blaha Christoph , Kablitz Stephan , Hennecke Dietmar K. , Schmidt-Eisenlohr Uwe , Pirker Klaus , Haselhoff Susanne 
Published: August 2014

The design of an aft-swept transonic compressor rotor and the investigation of its flow field compared to the radial baseline rotor are reported. Both rotors were designed using a 3D Euler solver with body forces. Through the choice of composite material using carbon fibres, high amounts of sweep and lean could be imparted to the blades without adding mass to the rotor assembly. No compromise between aerodynamic and structural constraints had to be made.
The swept design as well as the radial base-line rotor were investigated using the commercial RANS solver CFX-TASCflow to validate the design. Complete speed lines at design speed were computed for both rotors.
The analytical results showed similar peak efficiency and indicate that the swept rotor’s stall margin is reduced as compared to the base-line rotor. The resulting flow field of the aft-swept rotor is described in this paper and an attempt is made to discuss the fidelity of the design tools used.
Tip-Clearance Actuation With Magnetic Bearings for High-Speed Compressor Stall Control
Authors: Spakovszky Z. S. , Paduano J. D. , Larsonneur R. , Traxler A. , Bright M. M. 
Published: August 2014

Magnetic bearings are widely used as active suspension devices in rotating machinery, mainly for active vibration control purposes. The concept of active tip clearance control suggests a new application of magnetic bearings as servo-actuators to stabilize rotating stall in axial compressors.
This paper presents a first-of-a-kind feasibility study of an active stall control experiment with a magnetic bearing servo-actuator in the NASA Glenn high-speed single-stage compressor test facility. Together with CFD and experimental data a two-dimensional, incompressible compressor stability model was used in a stochastic estimation and control analysis to determine the required magnetic bearing performance for compressor stall control. The resulting requirements introduced new challenges to the magnetic bearing actuator design. A magnetic bearing servo-actuator was designed which fulfilled the performance specifications. Control laws were then developed to stabilize the compressor shaft. In a second control loop, a constant gain controller was implemented to stabilize rotating stall. A detailed closed loop simulation at 100% corrected design speed resulted in a 2.3% reduction of stalling mass flow which is comparable to results obtained in the same compressor by Weigl et al. (1998) using unsteady air injection.
The design and simulation results presented here establish the viability of magnetic bearings for stall control in aero-engine high-speed compressors. Furthermore the paper outlines a general design procedure to develop magnetic bearing servo-actuators for high-speed turbomachinery.
Control of Secondary Flows in a Turbine Nozzle Guide Vane by Endwall Contouring
Authors: Shih T. I-P. , Lin Y.-L. , Simon T. W. 
Published: August 2014

Computations were performed to study the three-dimensional flow and temperature distribution in a nozzle guide vane that has one flat and one contoured endwall with and without film cooling injected from two slots, one on each endwall located just upstream of the airfoil. For the contoured endwall, two locations of the same contouring were investigated, one with all contouring upstream of the airfoil and another with the contouring starting upstream of the airfoil and continuing through the airfoil passage.
Results obtained show that when the contouring is all upstream of the airfoil, secondary flows on both the flat and the contoured endwalls are similar in magnitude. When the contouring starts upstream of the airfoil and continues through the airfoil passage, secondary flows on the contoured endwall are markedly weaker than those on the flat endwall. With weaker secondary flows on the contoured endwall, film-cooling effectiveness there is greatly improved.
This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy. Effects of turbulence were modeled by the low Reynolds number shear-stress transport k-ω model. Solutions were generated by a cell-centered, finite-volume method that uses third-order accurate flux-difference splitting of Roe with limiters and multigrid acceleration of a diagonalized ADI scheme with local time stepping on patched/embedded structured grids.
A Multimedia Aeroengine Design Course With Industry Support
Authors: Hourmouziadis Jean , Schroeder Norbert , Biegi Klaus , Schmidt Klaus-Juergen , Servaty Stephan , Gärtner Wolfgang 
Published: August 2014

The Jet Propulsion Laboratory at the Berlin University of Technology has recently introduced a multimedia aeroengine design project under the working title “Project Jet Propulsion”. The seminar, in which the German aeroengine industry is actively involved, is directed at students who have successfully finished their basic engineering training course.
The objective of the course is to provide experience of all stages of the complete design process of an engine component in a genuine industrial working environment. The component is selected to ensure that a wide range of design requirements, including customer requirements, aero-thermodynamic and mechanical design, costing and certification, have to be taken into consideration. An experiment supporting the design completes the course.
The course is attended by a fixed number of students and lasts for one year. It involves fortnightly working sessions, which are organized the same way as they would be in the industry, with minutes being kept and action lists checked. The students are encouraged to work on their own initiative, identify the necessary tasks and set up a schedule to accomplish the work within the given time limit of the course duration.
Industry participates in a variety of ways. At the end of each working session experts from the companies involved join in a telephone conference, giving their comments on the work of the group and answering questions. A video conference supported by one of the industrial partners is also on the agenda. During the course, both companies involved are visited and progress is reviewed in an intermediate and a final design review respectively.
No scripts are handed out during the course. Communication is done by e-mail and progress reports, memoranda and minutes of the meetings are made available on the internet.
Design and Development of a Haynes 242® Nozzle Case for the Solar Mercury 50 Gas Turbine
Authors: McGregor Heather , Martin Devin , Browning Paul , Fitzpatrick Michael , Srivastava Krishna , Ishwar Venkat , Beden Isan , Tutton Nigel 
Published: August 2014

In a joint effort between Solar Turbines Incorporated, Haynes International, and Doncasters Blaenavon, concurrent component design and manufacturing process development were undertaken to produce a Haynes 242 turbine nozzle case for Solar Turbines’ Mercury 50 engine. The Mercury 50 is a high efficiency, 4.2 MW generator set, developed through a cooperative agreement with the U.S. Department of Energy within the Advanced Turbine Systems (ATS) Program. Significant effort was applied to development of a reduced lead time, reliable, low cost process for producing a component with properties meeting design requirements. The resulting process involves the forging of (508-mm) 20-inch diameter ingots to (308-mm) 12-inch diameter billets, and ring rolling each billet to the final pre-machined shape. Further refinement in both billet manufacture and ring rolling are being conducted. The resulting component benefits from the desirable elevated temperature properties and uncoated oxidation resistance of Haynes 242, a next-generation, low thermal expansion alloy.
In this paper, critical aspects of the turbine nozzle case design, and alloy process development will be presented. Microstructural evaluation of various billet forging processing routes will be related to mechanical properties, which in turn will be evaluated relative to design requirements.
The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis
Authors: Shaheen Eman , De Keyzer Frederik , Bosmans Hilde , Dance David R. , Young Kenneth C. , Ongeval Chantal Van 
Published: August 2014

Purpose:This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images.Methods:Twenty‐five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with an iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses.Results:The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly suggestive for malignancy (BIRADS 5) indicating the required variety of shapes and margins of these models. The assessment of the BIRADS scores for all observers indicated good agreement based on Kendall's coefficient for both the 2D and the tomosynthesis evaluations. The paired analysis of the BIRADS scores between 2D and tomosynthesis for each observer revealed consistent behavior for the real and simulated masses.Conclusions:A database of 3D mass models, with variety of shapes and margins, was validated for the realism of their appearance for 2D digital mammography and for breast tomosynthesis. This database is suitable for use in future observer performance studies whether in virtual clinical trials or in patient images with simulated lesions.
Interactive lung segmentation in abnormal human and animal chest CT scans
Authors: Kockelkorn Thessa T. J. P. , Schaefer‐Prokop Cornelia M. , Bozovic Gracijela , Muñoz‐Barrutia Arrate , van Rikxoort Eva M. , Brown Matthew S. , de Jong Pim A. , Viergever Max A. , van Ginneken Bram 
Published: August 2014

Purpose:Many medical image analysis systems require segmentation of the structures of interest as a first step. For scans with gross pathology, automatic segmentation methods may fail. The authors’ aim is to develop a versatile, fast, and reliable interactive system to segment anatomical structures. In this study, this system was used for segmenting lungs in challenging thoracic computed tomography (CT) scans.Methods:In volumetric thoracic CT scans, the chest is segmented and divided into 3D volumes of interest (VOIs), containing voxels with similar densities. These VOIs are automatically labeled as either lung tissue or nonlung tissue. The automatic labeling results can be corrected using an interactive or a supervised interactive approach. When using the supervised interactive system, the user is shown the classification results per slice, whereupon he/she can adjust incorrect labels. The system is retrained continuously, taking the corrections and approvals of the user into account. In this way, the system learns to make a better distinction between lung tissue and nonlung tissue. When using the interactive framework without supervised learning, the user corrects all incorrectly labeled VOIs manually. Both interactive segmentation tools were tested on 32 volumetric CT scans of pigs, mice and humans, containing pulmonary abnormalities.Results:On average, supervised interactive lung segmentation took under 9 min of user interaction. Algorithm computing time was 2 min on average, but can easily be reduced. On average, 2.0% of all VOIs in a scan had to be relabeled. Lung segmentation using the interactive segmentation method took on average 13 min and involved relabeling 3.0% of all VOIs on average. The resulting segmentations correspond well to manual delineations of eight axial slices per scan, with an average Dice similarity coefficient of 0.933.Conclusions:The authors have developed two fast and reliable methods for interactive lung segmentation in challenging chest CT images. Both systems do not require prior knowledge of the scans under consideration and work on a variety of scans.
Development of a novel depth of interaction PET detector using highly multiplexed G‐APD cross‐strip encoding
Authors: Kolb A. , Parl C. , Mantlik F. , Liu C. C. , Lorenz E. , Renker D. , Pichler B. J. 
Published: August 2014

Purpose:The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small‐bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields.Methods:The approach was based on Geiger mode avalanche photodiode (G‐APD) detectors with cross‐strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G‐APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated 18F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator.Results:All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 ± 0.15 mm.Conclusions:The novel DoI PET detector, which is based on strip G‐APD arrays, yielded a DoI resolution of 2.9 mm and excellent timing and energy resolution. Its high multiplexing factor reduces the number of electronic channels. Thus, this cross‐strip approach enables low‐cost, high‐performance PET detectors for dedicated small animal PET and PET/MRI and potentially clinical PET/MRI systems.
Draft Genome Sequence of the Obligately Alkaliphilic Sulfate-Reducing Bacterium Desulfonatronum thiodismutans Strain MLF1
Authors: Trubitsyn Denis , Geurink Corey , Pikuta Elena , Lefèvre Christopher T. , McShan W. Michael , Gillaspy Allison F. , Bazylinski Dennis A. 
Published: August 2014

ABSTRACT

Desulfonatronum thiodismutans
strain MLF1, an alkaliphilic bacterium capable of sulfate reduction, was isolated from Mono Lake, California. Here we report the 3.92-Mb draft genome sequence comprising 34 contigs and some results of its automated annotation. These data will improve our knowledge of mechanisms by which bacteria withstand extreme environments.
Quality and safety in the transitional care of the elderly (phase 2): the study protocol of a quasi-experimental intervention study for a cross-level educational programme
Authors: Storm Marianne , Groene Oliver , Testad Ingelin , Dyrstad Dagrunn N , Heskestad Randi N , Aase Karina 
Published: August 2014

IntroductionTransitional care and patient handover are important areas to ensure quality and safety in elderly healthcare services. Previous studies showed that healthcare professionals have little knowledge of the setting they are transferring patients to and a limited understanding of roles and functions; these constitute barriers to effective communication and shared care responsibilities across levels of care.AimThe main objective is to implement a cross-level education-based intervention programme with healthcare professionals aimed at (1) increasing professionals’ awareness and competencies about quality and safety in the transitional care of the elderly; (2) creating a discussion platform for knowledge exchange and learning across levels and units of care and (3) improving patient safety culture, in particular, in transitional care.Methods and analysisA quasi-experimental control group study design with an intervention group and a control group; this includes a pretest, post-test and 1-year follow-up test assessment of patient safety culture. Qualitative data will be collected during the intervention programme and between the measurements. The study design will be beneficial for addressing the effects of the cross-level educational intervention programme on reports of patient safety culture and for addressing the feasibility of the intervention measures.Ethics and disseminationThe study has been approved by the Regional Committees for Medical and Health Research Ethics in Norway, Ref. No. 2011/1978. The study is based on informed written consent; informants can withdraw from the study at any point in time. The results will be disseminated at research conferences, in peer review journals and through public presentations outside the scientific community.
Decentralized Fault-Tolerant Event Correlation
Authors: Wilkin Gregory Aaron , Eugster Patrick , Jayaram K. R. 
Published: August 2014

Despite the prognosed use of event correlation techniques for monitoring critical complex infrastructures or dealing with disasters in the physical world, little work exists on making event correlation systems themselves tolerant to failure. Existing systems either provide no guarantees on event deliveries, do not support multicast and thus provide no guarantees across individual processes, or then rely on centralized components or strong assumptions on the infrastructure.
The FAIDECS system attempts to reconcile strong guarantees with practical performance in the presence of process crash failures. To that end, the FAIDECS system uses an overlay network with specific guarantees aligned with its proposed correlation language and guarantees. However, the language proposed lacks expressivity, and the system itself supports only very specific rigid semantics, incapable of supporting even fundamental features like sliding windows.
After providing a comprehensive overview of the FAIDECS model and system, this article bridges the gap between strong guarantees and more established correlation languages and systems in several steps. First, we propose alternative semantics for several modules of the FAIDECS matching engine and revisit guarantees. Second, we pinpoint which guarantees are contradicted by which combinations of semantic options. Third, we investigate four correlation languages—StreamSQL, EQL, CEL, and TESLA—showing which semantic options their respective features correspond to in our model, and thus, ultimately, which guarantees of FAIDECS are maintained by which language features.
Dynamical and Microphysical Evolution during Mixed-Phase Cloud Glaciation Simulated Using the Bulk Adaptive Habit Prediction Model
Authors: Sulia Kara J. , Morrison Hugh , Harrington Jerry Y. 
Published: August 2014

Abstract
A bulk microphysics scheme predicting ice particle habit evolution has been implemented in the Weather Research and Forecasting Model. Large-eddy simulations are analyzed to study the effects of ice habit and number concentration on the bulk ice and liquid masses, dynamics, and lifetime of Arctic mixed-phase boundary layer clouds. The microphysical and dynamical evolution simulated using the adaptive habit scheme is compared with that assuming spherical particles with a density of bulk ice or a reduced density and with mass–dimensional parameterizations. It is found that the adaptive habit method returns an increased (decreased) ice (liquid) mass as compared to spheres and provides a more accurate simulation as compared to dendrite mass–size relations.
Using the adaptive habit method, simulations are then completed to understand the microphysical and dynamical interactions within a single-layer mixed-phase stratocumulus cloud observed during flight 31 of the Indirect and Semi-Direct Aerosol Campaign. With cloud-top longwave radiative cooling as a function of liquid mass acting as the primary dynamic driver of turbulent eddies within these clouds, the consumption of liquid at the expense of ice growth and subsequent sedimentation holds a strong control on the cloud lifetime. Ice concentrations ≥ 4 L−1 collapse the liquid layer without any external maintaining sources. Layer maintenance is possible at 4 L−1 when a constant cloud-top cooling rate or the water mass lost due to sedimentation is supplied. Larger concentrations require a more substantial source of latent or sensible heat for mixed-phase persistence.