bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Mistuning Characteristics of Bladed Disks From Free Response Data — Part II
Authors: Mignolet Marc P. , Delor Jason P. , Rivas-Guerra Alejandro 
Published: December 2014

The focus of the present investigation is on the estimation of the dynamic properties, i.e. masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example in a broach block test.
Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. Three distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to insure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade-to-blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function”. Finally, the third approach provides a bridge between the first two methods being based on the second but yielding a mistuning model similar to that of the first approach. The accuracy of these three techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
Determining the Affordability of Advanced Propulsion Systems
Authors: Mehta Paul P. , Evans Jerry W. , Ludwig Arthur L. 
Published: December 2014

The Integrated High Performance Turbine Engine Technology (IHPTET) is a joint Air Force, Navy, Army, DARPA, NASA, and industry initiative focused on developing higher performance turbine engines. The goal of IHPTET is to develop and demonstrate propulsion systems that would, by the turn of the century, double propulsion capability (1987 base year). For this reason, IHPTET engines are now test beds for a high number of advanced composites, intermetallics and single crystal alloys. While satisfying the performance requirements, the program has another salient objective of cost reduction.
This paper will discuss an approach for cost estimating and modeling of components and sub-components, and demonstrate the benefits of employing simulations. Traditional approaches have relied on comparative techniques utilizing complexity factors or Cost Estimating Relationships (CER’s). For advanced materials, these approaches are inadequate, primarily due to non-existence of historic data. A further weakness is their inability to identify cost drivers and quantify cost avoidance potential. Process-oriented cost estimating, albeit cumbersome during build-up and requiring detailed knowledge of manufacturing and process technology, provides a stable foundation for development of a comprehensive cost modeling system. Manufacturing Process Flow Simulation (MPFS) aids in evaluating evolving manufacturing processes (in infancy), studying the impact of alternate manufacturing processes and conducting what-if studies. MPFS can then be incorporated selectively into a cost modeling architecture capable of evaluating production cost for sub-components, components, and complete engines.
Performance Modeling as an Aid in the Preparation of a Test Code for IGCC Plants, PTC 47
Authors: Horazak Dennis A. , Archer David H. 
Published: December 2014

An ASME performance test code. PTC 47, for integrated gasification combined cycle, IGCC. plants is currently being written. This code will include definitions of the significant overall plant and plant component performance results — input, output, and effectiveness. It will indicate the measurements and measurement techniques required to calculate these results, and estimate systematic uncertainties associated with each measurement, as well as random uncertainties due to the measuring device or variations in plant conditions during the test. The code writing committee is making use of mathematical models of the performance of various IGCC power plant configurations to aid in the work of code preparation and testing.
The objective of this paper is to describe how computerized system performance models are now being used in the preparation of PTC 47, and to indicate how such models might be used in the conduct of performance tests in the future. The general form of a system performance model is discussed to clarify how it relates to correction factors for system performance parameters — input, output, and effectiveness: but the paper does not include defining or solving the actual equations of a system performance model.
The Role of Fuel Moisture in Gas Turbine Processes
Authors: Raiko Markku O. , Raiko Risto A. 
Published: December 2014

Imatran Voima (TVO) is the biggest energy producer in Finland. IVO builds, owns and operates several biomass combustion power plants and carries out active R&D work on further development of small-scale biomass and peat-fired power plants. Both conventional power plants based on fluidized bed boilers and future power plants based on gasification are also developed by IVO.
Typically, biomass fuels have high moisture content. High moisture content of fuel has, however, a negative effect on power generation cycles because of higher combustion losses.
IVO has researched and developed a steam drying system for small-scale gasification power plants for the sole domestic fuels peat and biomass. This is described and the experience gained in testing it is briefly reviewed.
The main focus of this paper is the thermal analysis of pressurized steam drying for biomass gasification power plants. Special emphasis is given to the thermal analysis of fuel moisture in alternative power plant processes. Fuel moisture removal is analyzed as a separate process.
Advantages of the LV100 as a Power Producer in a Hybrid Propulsion System for Future Fighting Vehicles
Authors: Koschier Angelo V. , Mauch Hagen R. 
Published: December 2014

The core of any hybrid propulsion system is a high power density, low weight, and fuel efficient electric energy producer. The LV100 recuperated turbine engine is such a system. This engine is well suited to provide electric power efficiently at a volume and weight significantly lower than current systems. Originally designed for vehicular use and environment to drive a Hydrokinetic transmission, the turbine’s high output speed lends itself to incorporate into the engine design an advanced generating device.
This LV100 engine-based electric energy producer will provide in excess of 1MW of electric power in a volume of under one cubic meter at a weight of about 2500 pounds at fuel efficiencies comparable to advanced vehicular diesel engines.
Recent state-of-the-art improvements in materials and component technology will permit further reductions in volume/weight and increase the system fuel efficiency.
The technologies required to reach a volume of under one cubic meter, the system performance projections obtainable by technology upgrades and the program achievements to date are discussed.
Second Vane Endwall Heat Transfer Reduction by Iceform Contouring
Authors: LaFleur Ronald S. , Whitten Timothy S. , Araujo Juan A. 
Published: December 2014

Endwall heat transfer within high pressure turbines is important in the quest for higher gas turbine combustion temperatures, improved cycle performance and longer part life. In this paper, the iceformation design method was used to reduce endwall heat transfer by contouring the endwall, altering the secondary flows that produce elevated endwall heat transfer load and obtaining an isothermal endwall geometry. Iceformation is analogous to metal melting regions where a hot fluid alters the isothermal surface shape of a part being maintained by a cooling fluid. The passage flow, heat transfer and geometry evolve together under the constraints of flow and thermal boundary conditions.
The iceformation concept is not media dependent and can be used in analogous flows and materials to evolve novel boundary shapes. In the past, this method has been shown to reduce aerodynamic drag and total pressure loss in flows such as diffusers and cylinder/endwall junctures. This paper adds to the iceformation design record by investigating endwall surface heat transfer reduction in an air flow. The second vane endwall heat transfer problem is important as combustion temperatures rise with the demand for higher thrust or work output and with the limited amount of cooling air devoted to components beyond the first stage. A Reynolds number matched geometry reduced the averaged endwall Stanton number by 24% compared to the rotationally symmetric geometry of an Energy Efficiency Engine (E3) second vane endwall. The iceformation method has applications in experimentally or computationally shaping an isothermal endwall geometry prior to detailed design of internal convection and film cooling circuits.
Influence of Compressor Deterioration on Engine Dynamic Behavior and Transient Stall-Margin
Authors: Spakovszky Z. S. , Gertz J. B. , Sharma O. P. , Paduano J. D. , Epstein A. H. , Greitzer E. M. 
Published: December 2014

This paper presents an experimental and analytical investigation of compressor stability assessment during engine transient operation. A 2-dimensional, linear, compressible, state-space analysis of stall-inception (Feulner et al. (1996)) was modified to account for engine transients and deterioration, with the latter modeled as increased tip-clearance and flow blockage.
Experiments were performed on large commercial aircraft engines in both undeteriorated and deteriorated states. Unsteady measurements of pressure in these test engines during rapid accelerations revealed the growth of pre-stall disturbances, which rotate at rotor speed and at approximately half rotor speed. These disturbances are stronger in deteriorated engines.
The model showed that the signal at shaft speed was the first compressible system mode, whose frequency is near shaft speed, excited by geometric nonuniformities. The computed behavior of this mode during throttle transients closely matched engine data. The signal increased in strength as stall was approached and as the engine deteriorated. This work firmly establishes the connection between observed signals in the these engines and first principles stability models.
The ANACONDA algorithm for deformable image registration in radiotherapy
Authors: Weistrand Ola , Svensson Stina 
Published: December 2014

Purpose:The purpose of this work was to describe a versatile algorithm for deformable image registration with applications in radiotherapy and to validate it on thoracic 4DCT data as well as CT/cone beam CT (CBCT) data.Methods:ANAtomically CONstrained Deformation Algorithm (ANACONDA) combines image information (i.e., intensities) with anatomical information as provided by contoured image sets. The registration problem is formulated as a nonlinear optimization problem and solved with an in‐house developed solver, tailored to this problem. The objective function, which is minimized during optimization, is a linear combination of four nonlinear terms: 1. image similarity term; 2. grid regularization term, which aims at keeping the deformed image grid smooth and invertible; 3. a shape based regularization term which works to keep the deformation anatomically reasonable when regions of interest are present in the reference image; and 4. a penalty term which is added to the optimization problem when controlling structures are used, aimed at deforming the selected structure in the reference image to the corresponding structure in the target image.Results:To validate ANACONDA, the authors have used 16 publically available thoracic 4DCT data sets for which target registration errors from several algorithms have been reported in the literature. On average for the 16 data sets, the target registration error is 1.17 ± 0.87 mm, Dice similarity coefficient is 0.98 for the two lungs, and image similarity, measured by the correlation coefficient, is 0.95. The authors have also validated ANACONDA using two pelvic cases and one head and neck case with planning CT and daily acquired CBCT. Each image has been contoured by a physician (radiation oncologist) or experienced radiation therapist. The results are an improvement with respect to rigid registration. However, for the head and neck case, the sample set is too small to show statistical significance.Conclusions:ANACONDA performs well in comparison with other algorithms. By including CT/CBCT data in the validation, the various aspects of the algorithm such as its ability to handle different modalities, large deformations, and air pockets are shown.
Biochemical Characterization of the POM-1 Metallo-β-Lactamase from Pseudomonas otitidis
Authors: Borgianni Luisa , De Luca Filomena , Thaller Maria Cristina , Chong Yunsop , Rossolini Gian Maria , Docquier Jean-Denis 
Published: December 2014

ABSTRACT

The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by
Pseudomonas otitidis
, a pathogen causing otic infections. The enzyme was overproduced in
Escherichia coli
BL21(DE3), purified by chromatography, and subjected to structural and functional analysis. The purified POM-1 is a tetrameric enzyme of broad substrate specificity with higher catalytic activities with penicillins and carbapenems than with cephalosporins.
Enantiospecific Reassessment of the Pharmacokinetics and Pharmacodynamics of Oral Eflornithine against Late-Stage Trypanosoma brucei gambiense Sleeping Sickness
Authors: Jansson-Löfmark R. , Na-Bangchang K. , Björkman S. , Doua F. , Ashton M. 
Published: December 2014

ABSTRACT

This study aimed to characterize the stereoselective pharmacokinetics of oral eflornithine in 25 patients with late-stage
Trypanosoma brucei
gambiense
sleeping sickness. A secondary aim was to determine the concentrations of
l
- and
d
-eflornithine required in plasma or cerebrospinal fluid (CSF) for an efficient eradication of the
T. brucei gambiense
parasites. Patients were randomly allocated to receive either 100 (group I,
n
= 12) or 125 (group II,
n
= 13) mg/kg of body weight of drug every 6 h for 14 days. The concentrations of
l
- and
d
-eflornithine in the plasma and CSF samples were measured using a stereospecific liquid chromatographic method. Nonlinear mixed-effects modeling was used to characterize the plasma pharmacokinetics. The plasma concentrations of
l
-eflornithine were on average 52% (95% confidence interval [CI], 51, 54%;
n
= 321) of the
d
-enantiomer concentrations. The typical oral clearances of
l
- and
d
-eflornithine were 17.4 (95% CI, 15.5, 19.3) and 8.23 (95% CI, 7.36, 9.10) liters/h, respectively. These differences were likely due to stereoselective intestinal absorption. The distributions of eflornithine enantiomers to the CSF were not stereoselective. A correlation was found between the probability of cure and plasma drug exposure, although it was not more pronounced for the
l
-enantiomer than for that of total eflornithine. This study may explain why oral treatment for late-stage human African trypanosomiasis (HAT) patients with racemic eflornithine has previously failed; the more potent
l
-enantiomer is present at much lower concentrations in both plasma and CSF than those of the
d
-enantiomer. Eflornithine stereoselective pharmacokinetics needs to be considered if an oral dosage regimen is to be explored further.
Evaluation of the Pharmacokinetic Interaction between Repeated Doses of Rifapentine or Rifampin and a Single Dose of Bedaquiline in Healthy Adult Subjects
Authors: Winter Helen , Egizi Erica , Murray Stephen , Erondu Ngozi , Ginsberg Ann , Rouse Doris J. , Severynse-Stevens Diana , Pauli Elliott 
Published: December 2014

ABSTRACT

This study assessed the effects of rifapentine or rifampin on the pharmacokinetics of a single dose of bedaquiline and its M2 metabolite in healthy subjects using a two-period single-sequence design. In period 1, subjects received a single dose of bedaquiline (400 mg), followed by a 28-day washout. In period 2, subjects received either rifapentine (600 mg) or rifampin (600 mg) from day 20 to day 41, as well as a single bedaquiline dose (400 mg) on day 29. The pharmacokinetic profiles of bedaquiline and M2 were compared over 336 h after the administration of bedaquiline alone and in combination with steady-state rifapentine or rifampin. Coadministration of bedaquiline with rifapentine or rifampin resulted in lower bedaquiline exposures. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for the maximum observed concentration (
C
max
), area under the concentration-time curve to the last available concentration time point (AUC

0–
t

), and AUC extrapolated to infinity (AUC
0–inf
) of bedaquiline were 62.19% (53.37 to 72.47), 42.79% (37.77 to 48.49), and 44.52% (40.12 to 49.39), respectively, when coadministered with rifapentine. Similarly, the GMRs and 90% CIs for the
C
max
, AUC

0–
t

, and AUC
0–inf
of bedaquiline were 60.24% (51.96 to 69.84), 41.36% (37.70 to 45.36), and 47.32% (41.49 to 53.97), respectively, when coadministered with rifampin. The
C
max
, AUC

0–
t

, and AUC
0–inf
of M2 were also altered when bedaquiline was coadministered with rifapentine or rifampin. Single doses of bedaquiline, administered alone or with multiple doses of rifapentine or rifampin, were well tolerated, with no safety concerns related to coadministration. Daily administration of rifapentine to patients with tuberculosis presents the same drug interaction challenges as rifampin and other rifamycins. Strong inducers of the cytochrome P450 isoenzyme CYP3A4 should be avoided when considering the use of bedaquiline. (This study is registered at clinicaltrials.gov under identifier NCT02216331.)
Pharmacodynamic Target Evaluation of a Novel Oral Glucan Synthase Inhibitor, SCY-078 (MK-3118), Using an
In Vivo
Murine Invasive Candidiasis Model
Authors: Lepak Alexander J. , Marchillo Karen , Andes David R. 
Published: December 2014

ABSTRACT

Echinocandins inhibit the synthesis of β-1,3-
d
-glucan in
Candida
and are the first-line therapy in numerous clinical settings. Their use is limited by poor oral bioavailability, and they are available only as intravenous therapies. Derivatives of enfumafungin are novel orally bioavailable glucan synthase inhibitors. We performed an
in vivo
pharmacodynamic (PD) evaluation with a novel enfumafungin derivative, SCY-078 (formerly MK-3118), in a well-established neutropenic murine model of invasive candidiasis against
C. albicans
,
C. glabrata
, and
C. parapsilosis
. The SCY-078 MICs varied 8-fold. Oral doses of 3.125 to 200 mg/kg SCY-078 salt in sterile water produced peak levels of 0.04 to 2.66 μg/ml, elimination half-lives of 5.8 to 8.5 h, areas under the concentration-time curve from 0 to 24 h (AUC
0–24 h
) of 0.61 to 41.10 μg · h/ml, and AUC from 0 to infinity (AUC
0—∞
) values of 0.68 to 40.31 μg · h/ml. The pharmacokinetics (PK) were approximately linear over the dose range studied. Maximum response (
E
max
) and PK/PD target identification studies were performed with 4
C. albicans
, 4
C. glabrata
, and 3
C. parapsilosis
isolates. The PD index AUC/MIC was explored by using total (
t
AUC) and free (
f
AUC) drug concentrations. The maximum responses were 4.0, 4.0, and 4.3 log
10
CFU/kidney reductions for
C. albicans
,
C. glabrata
, and
C. parapsilosis
, respectively. The AUC/MIC was a robust predictor of efficacy (
R
2
, 0.53 to 0.91). The 24-h PD targets were a static dose of 63.5 mg/kg, a
t
AUC/MIC of 500, and an
f
AUC/MIC of 1.0 for
C. albicans
; a static dose of 58.4 mg/kg, a
t
AUC/MIC of 315, and an
f
AUC/MIC of 0.63 for
C. glabrata
; and a static dose of 84.4 mg/kg, a
t
AUC/MIC of 198, and an
f
AUC/MIC of 0.40 for
C. parapsilosis
. The mean
f
AUC/MIC values associated with a 1-log kill endpoint against these species were 1.42, 1.26, and 0.91 for
C. albicans
,
C. glabrata
, and
C. parapsilosis
, respectively. The static and 1-log kill endpoints were measured relative to the burden at the start of therapy. The static and 1-log kill doses, as well as the total and free drug AUC/MIC PD targets, were not statistically different between species but were numerically lower than those observed for echinocandins. SCY-078 is a promising novel oral glucan synthase inhibitor against
Candida
species, and further investigation is warranted.
Detailed Mutational Analysis of Vga(A) Interdomain Linker: Implication for Antibiotic Resistance Specificity and Mechanism
Authors: Lenart Jakub , Vimberg Vladimir , Vesela Ludmila , Janata Jiri , Balikova Novotna Gabriela 
Published: December 2014

ABSTRACT
Detailed mutational analysis examines the roles of individual residues of the Vga(A) linker in determining the antibiotic resistance phenotype. It defines a narrowed region of residues 212 to 220 whose composition determines the resistance specificity to lincosamides, pleuromutilins, and/or streptogramins A. From the analogy with the recently described function of the homologous ABC-F protein EttA as a translational factor, we infer that the Vga(A) linker interacts with the ribosome and directly or indirectly affects the binding of the respective antibiotic.
Pregnancy-associated outcomes in women who spent some of their childhood looked after by local authorities: findings from the UK Millennium Cohort Study
Authors: Botchway Stella K , Quigley Maria A , Gray Ron 
Published: December 2014

ObjectivesThere has been very little description of the health and social outcomes at pregnancy and early motherhood of girls who were previously looked after by local authorities. The objectives of this study were to compare the sociodemographic and health profiles of mothers who had spent time in a children's home or with foster parents as a child to mothers who had not. In particular, to examine associations between being looked after and the likelihood of smoking during pregnancy, birth weight, the presence of symptoms of maternal depression and the initiation of breastfeeding.DesignA retrospective cross-sectional study using the baseline questionnaire of the Millennium Cohort Study.SettingThe UK.ParticipantsA nationally representative study of 18 492 mothers of babies born in the UK during 2000–2002.ExposureA history of spending time in a children's home or with foster parents.Outcome measures(1) Smoking during pregnancy; (2) low birth weight; (3) symptoms of maternal depression and (4) initiation of breastfeeding.ResultsIn univariable analyses, women who had been looked after by local authorities were significantly less likely to be of a higher social class, live in a high-income household or have achieved a high level of education. They were more likely to have a low-birthweight baby and be a single parent. In multivariable analyses, women who had been looked after by local authorities were more likely to smoke during pregnancy (adjusted OR 3.0 95% CI 2.14 to 4.3) and were more likely to have symptoms of depression (adjusted OR 1.98 95% CI 1.4 to 2.7) compared with women who had not been looked after.ConclusionsOur results suggest that these women carry social disadvantage into motherhood, with the potential of continuing the cycle of deprivation. There is a case for increasing our attention on this group, which can be readily accessed by maternity and early years’ services.