bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Design and Development of the RB211 Dry Low Emissions Engine
Authors: Summerfield Alan H. , Pritchard David , Tuson Dave W. , Owen David A. 
Published: February 2015

To meet current and proposed worldwide emissions regulations without recourse to steam or water injection, the Industrial RB211 is being upgraded with a premix lean burn series staged combustion system. To incorporate this system a reverse flow cannular concept was adopted. This design retains the inherent proven modular construction and is suitable for retrofit.
This paper discusses the mechanical design analysis undertaken to ensure integration of the chosen solution into the RB211. Theoretical studies, combustion laboratory tests, aerodynamic scale and full size laboratory tests, together with extensive computer modelling were used to ensure the timely achievement of this design study.
To verify the design analyses a detailed full power test programme is in place, which is to be followed by field trials with a pre-production engine during 1993.
Endwall Effects at Two Tip Clearances in a Multistage Axial Flow Compressor With Controlled Diffusion Blading
Authors: Howard M. A. , Ivey P. C. , Barton J. P. , Young K. F. 
Published: February 2015

Effects of tip clearance, secondary flow, skew and corner stall on the performance of a multi-stage compressor with controlled diffusion blading have been studied experimentally. Measurements between 1% and 99% annulus height were carried out in both the first and the third stages of a four-stage low-speed compressor with repeating-stage blading.
Measurements were obtained at a datum rotor tip clearance and at a more aerodynamically desirable lower clearance. The consequence of the modified rotor tip clearance on both rotor and stator performance are examined in terms of loss coefficient and gas exit angle. Stator losses close to the casing are found to increase significantly when the clearance of an upstream rotor is increased. These increased stator losses cause 30% of the stage efficiency reduction which arises with increased rotor tip clearance.
The deviation angles due to tip clearance from the multi-stage measurements are found to be similar to data from single stage machines with conventional blading which suggests that the unsteady flow phenomena associated with the multi-stage environment do not dominate the physics of the flow.
Computer-Aided FT8® RAM Analysis With On Condition Maintenance
Authors: Gaudette T. L. , Fraser Larry , Della Villa S. A. 
Published: February 2015

Product reliability is influenced by both design and operating and maintenance practices. This means both the equipment manufacturer and the equipment’s operator have an impact on the systems’ achievable level of availability. Many variables such as application (utility or cogeneration) or service or duty cycle (peaking, cycling, or continuous duty), influence the expected availability/reliability of any unit. These variables and an understanding of the expected “economic demand” the unit must fill are important elements for a realistic and accurate reliability assessment. These variables also affect the expected maintenance costs associated with the unit.
Both the equipment manufacturer and the equipment operator have a vested interest in understanding and influencing this process. If the expected level of reliability/availability is a major requirement of the equipment owner/operator, then there must be an accurate understanding of how the reliability of the unit will be protected over the long term. Thus the unit first cost and life cycle cost can be estimated in a meaningful way.
The objective of this paper is to provide an assessment of proved design reliability along with the application of on condition maintenance of Turbo Power and Marine Systems’ (Turbo Power) most recent product introduction, the FT8. A computer-aided reliability analysis was made by Turbo Power with the support of Strategic Power Systems, Inc. (SPS), to demonstrate and support the suitability of the FT8 for both peaking and continuous duty applications utilizing on condition maintenance concepts. Consequently, the presentation of the RAM analysis is organized to assist in developing a complete and comprehensive understanding of the evolution of the product and to develop realistic RAM (Reliability, Availability, and Maintainability) and life cycle cost expectations.
Ceramic Composite Attachments for Transmission of High Torque Loads
Authors: Brockmeyer Jerry W. , Straub Andreas C. , Krieg Eric J. 
Published: February 2015

The use of fiber-reinforced ceramic matrix composites (FRCMC) for advanced turbopump (T/P) hot-section components offers a number of potential advantages relative to the use of ‘conventional’ materials. Among these advantages are reduced weight, enhanced life with reduced maintenance and improved performance achievable by increasing the turbine inlet temperature. FRCMC are, however, emerging materials, and their design and analysis present unique challenges. These composites have relatively low thermal expansion coefficients and low strain-to-failure characteristics, and they have nonlinear, anisotropic properties. These characteristics particularly complicate the design of attachments to mating metallic components within a T/P.
In an ongoing program*, an FRCMC stator and rotor for a rocket engine T/P are being developed for eventual ground test demonstration. The rotor attachment is designed to transmit high torque loads and provides an example of a design methodology which is compatible with current analytical capabilities. The approach used and described herein applies an empirically derived materials properties data base in combination with macromechanical analysis to reach a solution to this design challenge. This example demonstrates both the capabilities and the limitations of current design and analysis practices and provides direction for future development. A curvic coupling was chosen to meet the specific design goals and will be fabricated and tested to verify the design.
Fouling and Air Bleed Extracted Flow Influence on Compressor Performance
Authors: Cerri G. , Salvini C. , Procacci R. , Rispoli F. 
Published: February 2015

Compressor performance deterioration with operating time has been analyzed and a method for the description of actual scaled map curves is discussed. These curves are obtained from actual operating point data from the monitoring system. Suitable scaling functions have been introduced. An inverse stage stacking technique solution has been adopted to obtain reference quantities to be used with generalized curves. In order to account for machine peculiar real phenomena, shape factors have been introduced for best fitting of given data.
An example is presented to discuss the deteriorated compressor map and the influence of mass flows extracted from bleeds.
The Handling of a Variable Cycle Engine: The Selective Bleed Turbofan
Authors: Ulizar Inaki , Pilidis Pericles 
Published: February 2015

The selective bleed turbofan is a two shaft, three compressor, variable cycle aircraft engine. At subsonic flight speeds it operates as a medium bypass turbofan. It becomes a low bypass turbofan when flying faster and is capable of supersonic cruise in the dry mode.
The aim of this paper is to indicate the limits of operation of this power plant and to suggest control schemes that will allow satisfactory handling throughout the flight envelope.
The performance benefits of the engine have been described in previous publications. Here its limits of operation are shown for two critical conditions, both at an altitude of 11km. The resulting scheduling requirements of the appropriate engine control variables are indicated. These are the low pressure compressor variable stators, the nozzle areas and the fuel flow. These parameters have to be controlled independently by a sophisticated system. The control strategies simulated indicate satisfactory engine handling over a wide flight envelope.
Transonic Compressor Rotor Cascade With Boundary-Layer Separation: Experimental and Theoretical Results
Authors: Fuchs R. , Steinert W. , Starken H. 
Published: February 2015

A transonic compressor rotor cascade designed for an inlet Mach number of 1.09 and 14 degrees of flow turning has been redesigned for higher loading by an increased pitch-to-chord ratio. Test results, showing the influence of inlet Mach number and flow angle on cascade performance are presented and compared to data of the basic design. Loss-levels of both, the original and the redesigned higher loaded blade were identical at design condition, but the new design achieved even lower losses at lower inlet Mach numbers.
The computational design and analysis has been performed by a fast inviscid time-dependent code coupled to a viscous direct/inverse integral boundary-layer code. Good agreement was achieved between measured and predicted surface Mach number distributions as well as exit-flow angles.
A boundary-layer visualization method has been used to detect laminar separation bubbles and turbulent separation regions. Quantitative results of measured bubble positions are presented and compared to calculated results.
Combined-Cycle Power Plants From Gas Turbines and Geothermal Source Integration
Authors: Bettocchi R. , Cantore G. , Negri di Montenegro G. , Peretto A. , Gadda E. 
Published: February 2015

Geothermal power plants have difficulties due to the low conversion efficiencies achievable.
Geothermal integrated combined cycle proposed and analyzed in this paper is a way to achieve high efficiency.
In the proposed cycle the geothermal fluid energy is added, through suitable heat ecxhangers, to that of exhaust gases for generating a steam cycle.
The proposed cycle maintains the geothermal fluid segregated from ambient and this can be positive on the environmental point of view.
Many systems configurations, based on this possibility, can be taken into account to get the best thermodynamic result.
The perfomed analysis examines different possible sharings between the heat coming from geothermal and exhaust gases, and gives the resulting system efficiencies.
Various pressures of the geothermal steam and water dominated sources are also taken into account.
As a result the analysis shows that the integrated plant power output is largely greater than the total power obtained by summing the gas turbine and the traditional geothermal plant power output, considered separately.
Thermodynamic Design Considerations for Steam-Injected Gas Turbines
Authors: Noymer Peter D. , Wilson David Gordon 
Published: February 2015

Steam injection in gas turbines (steam raised from the energy of the exhaust and injected into one or more of the turbine stages) is an attractive option for cogeneration applications. From a thermodynamic point of view, however, there is little information available about methods for optimizing the use of the steam for injection into a gas turbine.
A computer model for an aeroderivative gas turbine is used to analyze the effect of steam injection on net power output and overall efficiency. The effects of varying the quantity of steam injected, the stations at which the steam is injected, and the temperature of the steam that is injected are assessed on a normalized basis, with the turbine-inlet temperature maintained from the simple-cycle design point.
The energy balance between the exhaust of the gas turbine and the flow of steam to be injected is the final constraint in selecting a steam-injected design point to maximize performance. For the engine in this study, increases of over 64% in net power output and 23% in overall efficiency can be achieved with roughly 16% steam/inlet air by mass, which represents all of the steam that can be produced by the exhaust stream for the given conditions.
Loss Mechanisms in Turbomachines
Authors: Denton J. D. 
Published: February 2015

The origins and effects of loss in turbomachines are discussed with the emphasis on trying to understand the physical origins of loss rather than on reviewing the available prediction methods. Loss is defined in terms of entropy increase and the relationship of this to the more familiar loss coefficients is derived and discussed. The sources of entropy are in general: Viscous effects in boundary layers, viscous effects in mixing processes, shock waves and heat transfer across temperature differences. These are first discussed in general and then the results are applied to turbomachinery flows. Understanding of the loss due to heat transfer requires some discussion of cycle thermodynamics. Sections are devoted to discussing: Blade boundary layer and trailing edge loss, tip leakage loss, endwall loss, effects of heat transfer and miscellaneous losses. The loss arising from boundary layer separation is particularly difficult to quantify. Most of the discussion is based on axial flow machines but a separate section is devoted to the special problems of radial flow machines.
In some cases, eg attached blade boundary layers, the loss mechanisms are well understood, but even so the loss can seldom be predicted with great accuracy. In many other cases, eg endwall loss, the loss mechanisms are still not clearly understood and prediction methods remain very dependent on correlations. The paper emphasises that the use of correlations should not be a substitute for trying to understand the origins of loss and suggests that a good physical understanding of the latter may be more valuable than a quantitative prediction.
ON THE DUAL POST CORRESPONDENCE PROBLEM
Authors: DAY JOEL D. , REIDENBACH DANIEL , SCHNEIDER JOHANNES C. 
Published: February 2015

The Dual Post Correspondence Problem asks whether, for a given word α, there exists a pair of distinct morphisms σ,τ, one of which needs to be non-periodic, such that σ(α) = τ(α) is satisfied. This problem is important for the research on equality sets, which are a vital concept in the theory of computation, as it helps to identify words that are in trivial equality sets only. Little is known about the Dual PCP for words α over larger than binary alphabets, especially for so-called ratio-primitive examples. In the present paper, we address this question in a way that simplifies the usual method, which means that we can reduce the intricacy of the word equations involved in dealing with the Dual PCP. Our approach yields large sets of words for which there exists a solution to the Dual PCP as well as examples of words over arbitrary alphabets for which such a solution does not exist.
Nonuniform wavelet frames in L2(ℝ)
Authors: Sharma Vikram , Manchanda P. 
Published: February 2015

Gabardo and Nashed, [Nonuniform multiresolution analysis and spectral pairs, J. Funct. Anal. 158 (1998) 209–241] introduced the nonuniform multiresolution analysis (NUMRA) whose translation set is not necessarily a group. The translation set is taken for elements in [Formula: see text], N ≥ 1 (an integer) and r is an odd integer with 1 ≤ r ≤ 2N - 1 such that r and N are relatively prime and ℤ is the set of all integers. In this paper, we construct wavelet frame over the translation set Λ on L2(ℝ). We call it nonuniform wavelet frame. We establish necessary and sufficient condition for such wavelet frame. An example is presented at the end.
Idealized Quasi-Biennial Oscillations in an Ensemble of Dry GCM Dynamical Cores
Authors: Yao Weiye , Jablonowski Christiane 
Published: February 2015

Abstract
The paper demonstrates that quasi-biennial oscillation (QBO)-like oscillations can be simulated in an ensemble of dry GCM dynamical cores that are driven by a simple Held–Suarez temperature relaxation and low-level Rayleigh friction. The tropical stratospheric circulations of four dynamical cores, which are options in NCAR’s Community Atmosphere Model, version 5 (CAM5), are intercompared. These are the semi-Lagrangian (SLD) and Eulerian (EUL) spectral transform, finite-volume (FV), and spectral element (SE) dynamical cores. The paper investigates how the model design choices impact the wave generation, propagation, and dissipation mechanisms in the equatorial region. SLD, EUL, and SE develop spontaneous QBO-like oscillations in the upper equatorial stratosphere, whereas FV does not sustain the oscillation. Transformed Eulerian-mean (TEM) analyses reveal that resolved waves are the dominant drivers of the QBOs. However, the Eliassen–Palm flux divergence is strongly counteracted by the TEM momentum budget residual, which represents the forcing by diffusion and thermal damping. Interestingly, a reversed Brewer–Dobson circulation accelerates the downward propagation of the SLD’s QBO, whereas the EUL’s and SE’s QBOs are slowed by a mean ascent. Waves are abundant in the SLD’s, EUL’s, and SE’s tropical atmosphere despite the absence of moist convection as a typical wave trigger. Dynamic instabilities are suggested as a wave-triggering mechanism in the troposphere and wave-dissipation process in the stratosphere. In particular, there are indications that the increased occurrences of strongly negative instability indicators in SLD, EUL, and SE are related to more vigorous wave activities and higher magnitudes of the resolved wave forcing in comparison to FV.
Evaluating Unsupervised Methods to Size and Classify Suspended Particles Using Digital In-Line Holography
Authors: Davies Emlyn J. , Buscombe Daniel , Graham George W. , Nimmo-Smith W. Alex M. 
Published: February 2015

AbstractSubstantial information can be gained from digital in-line holography of marine particles, eliminating depth-of-field and focusing errors associated with standard lens-based imaging methods. However, for the technique to reach its full potential in oceanographic research, fully unsupervised (automated) methods are required for focusing, segmentation, sizing, and classification of particles. These computational challenges are the subject of this paper, in which the authors draw upon data collected using a variety of holographic systems developed at Plymouth University, United Kingdom, from a significant range of particle types, sizes, and shapes. A new method for noise reduction in reconstructed planes is found to be successful in aiding particle segmentation and sizing. The performance of an automated routine for deriving particle characteristics (and subsequent size distributions) is evaluated against equivalent size metrics obtained by a trained operative measuring grain axes on screen. The unsupervised method is found to be reliable, despite some errors resulting from oversegmentation of particles. A simple unsupervised particle classification system is developed and is capable of successfully differentiating sand grains, bubbles, and diatoms from within the surfzone. Avoiding miscounting bubbles and biological particles as sand grains enables more accurate estimates of sand concentrations and is especially important in deployments of particle monitoring instrumentation in aerated water. Perhaps the greatest potential for further development in the computational aspects of particle holography is in the area of unsupervised particle classification. The simple method proposed here provides a foundation upon which further development could lead to reliable identification of more complex particle populations, such as those containing phytoplankton, zooplankton, flocculated cohesive sediments, and oil droplets.
A multicenter study on the effect of continuous hemodiafiltration intensity on antibiotic pharmacokinetics
Authors: Roberts Darren M , Liu Xin , Roberts Jason A , Nair Priya , Cole Louise , Roberts Michael S , Lipman Jeffrey , Bellomo Rinaldo ,   On behalf of the RENAL Replacement Therapy Study Investigators
Published: February 2015

Abstract
Introduction
Continuous renal replacement therapy (CRRT) may alter antibiotic pharmacokinetics and increase the risk of incorrect dosing. In a nested cohort within a large randomized controlled trial, we assessed the effect of higher (40 mL/kg per hour) and lower (25 mL/kg per hour) intensity CRRT on antibiotic pharmacokinetics.

Methods
We collected serial blood samples to measure ciprofloxacin, meropenem, piperacillin-tazobactam, and vancomycin levels. We calculated extracorporeal clearance (CL), systemic CL, and volume of distribution (Vd) by non-linear mixed-effects modelling. We assessed the influence of CRRT intensity and other patient factors on antibiotic pharmacokinetics.

Results
We studied 24 patients who provided 179 pairs of samples. Extracorporeal CL increased with higher-intensity CRRT but the increase was significant for vancomycin only (mean 28 versus 22 mL/minute; P = 0.0003). At any given prescribed CRRT effluent rate, extracorporeal CL of individual antibiotics varied widely, and the effluent-to-plasma concentration ratio decreased with increasing effluent flow. Overall, systemic CL varied to a greater extent than Vd, particularly for meropenem, piperacillin, and tazobactam, and large intra-individual differences were also observed. CRRT dose did not influence overall (systemic) CL, Vd, or half-life. The proportion of systemic CL due to CRRT varied widely and was high in some cases.

Conclusions
In patients receiving CRRT, there is great variability in antibiotic pharmacokinetics, which complicates an empiric approach to dosing and suggests the need for therapeutic drug monitoring. More research is required to investigate the apparent relative decrease in clearance at higher CRRT effluent rates.

Trial registration
ClinicalTrials.gov NCT00221013. Registered 14 September 2005.
A simple prognostic index based on admission vital signs data among patients with sepsis in a resource-limited setting
Authors: Asiimwe Stephen B , Abdallah Amir , Ssekitoleko Richard 
Published: February 2015

Abstract
Introduction
In sub-Saharan Africa, vital signs are a feasible option for monitoring critically ill patients. We assessed how admission vital signs data predict in-hospital mortality among patients with sepsis. In particular, we assessed whether vital signs data can be incorporated into a prognostic index with reduced segmentation in the values of included variables.

Methods
Subjects were patients with sepsis hospitalized in Uganda, who participated in two cohort studies. Using restricted cubic splines of admission vital signs data, we predicted probability of in-hospital death in the development cohort and used this information to construct a simple prognostic index. We assessed the performance of the index in a validation cohort and compared its performance to that of the Modified Early Warning Score (MEWS).

Results
We included 317 patients (167 in the development cohort and 150 in the validation cohort). Based on how vital signs predicted mortality, we created a prognostic index giving a score of 1 for: respiratory rates ≥30 cycles/minute; pulse rates ≥100 beats/minute; mean arterial pressures ≥110/<70 mmHg; temperatures ≥38.6/<35.6°C; and presence of altered mental state defined as Glasgow coma score ≤14; 0 for all other values. The proposed index (maximum score = 5) predicted mortality comparably to MEWS. Patients scoring ≥3 on the index were 3.4-fold (95% confidence interval (CI) 1.6 to 7.3, P = 0.001) and 2.3-fold (95% CI 1.1 to 4.7, P = 0.031) as likely to die in hospital as those scoring 0 to 2 in the development and validation cohorts respectively; those scoring ≥5 on MEWS were 2.5-fold (95% CI 1.2 to 5.3, P = 0.017) and 1.8-fold (95% CI 0.74 to 4.2, P = 0.204) as likely to die as those scoring 0 to 4 in the development and validation cohorts respectively.

Conclusion
Among patients with sepsis, a prognostic index incorporating admission vital signs data with reduced segmentation in the values of included variables adequately predicted mortality. Such an index may be more easily implemented when triaging acutely-ill patients. Future studies using a similar approach may develop indexes that can be used to monitor treatment among acutely-ill patients, especially in resource-limited settings.