bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Vane-Blade Spacing on Transonic Turbine Stage Aerodynamics: Part 1 — Time-Averaged Data and Analysis
Authors: Venable Brian L. , Delaney Robert A. , Busby Judy A. , Davis Roger L. , Dorney Daniel J. , Dunn Michael G. , Haldeman Charles W. , Abhari Reza S.
Published: December 2014

A comprehensive study has been performed to determine the influence of vane-blade spacing on transonic turbine stage aerodynamics. In Part I of this paper, an investigation of the effect of turbine vane-blade interaction on the time-mean airfoil surface pressures and overall stage performance parameters is presented. Experimental data for an instrumented turbine stage are compared to two- and three-dimensional results from four different time-accurate Navier-Stokes solvers. Unsteady pressure data were taken for three vane-blade row spacings in a short-duration shock tunnel using surface-mounted, high-response pressure sensors located along the midspan of the airfoils. Results indicate that while the magnitude of the surface pressure unsteadiness on the vane and blade changes significantly with spacing, the time-mean pressures and performance numbers are not greatly affected.
New Non-Dimensional Parameters in Fluid Mechanics and Their Application to Turbine Flowmeter Data Analysis
Authors: Mozumdar Subir , Islam Obaidul
Published: December 2014

Dimensional analysis has been used in experimental fluid mechanics for over a hundred years. Controllable and uncontrollable variables in an experiment can be efficiently organized into nondimensional groups or parameters. Such nondimensional parameters are used for geometric scaling, and for developing dynamic similitude in experimental processes. Commonly used nondimensional parameters in fluid mechanics include Reynold’s No., Mach No., Froude No., Weber No., Strouhal No., etc. Most modern text books and technical papers discuss the use of Buckingham Pi Theorem for developing the nondimensionalization process. An often ignored and somewhat older technique is the Rayleigh Method. Both the Pi Theorem and the Rayleigh Method are founded on the Principle of Dimensional Homogeneity, and require some experience in the grouping of physical variables. The present paper uses the Rayleigh method to develop two new nondimensional parameters. A discussion is presented about the use of the parameters in the application of turbine flowmeter calibration and test data analysis. It is shown that data analysis for turbine flowmeters is considerably simplified by the use of the new parameters.
Modeling of Turbulent Swirling Flame Stabilization in LPP Combustors
Authors: Smirnov A. , Lipatnikov A. , Chomiak J.
Published: December 2014

Combustion flows with swirl are investigated in the context of a lean premixed pre-vaporized combustor. The turbulent flame speed closure model implemented into the Kiva program appears to be efficient in utilizing computing time and memory. It also predicts a larger flame spread than a distributed reactor model. The effect of different turbulence and combustion models on flow recirculation patterns and heat release is reported.
3D Rans Calculations of Flow Through Turbine Volutes
Authors: Hasan R. G. M. , McGuirk J. J.
Published: December 2014

Due to their complex shape and complicated flow configuration, the volutes of turbocharger compressors and turbines appear to be a difficult component for both numerical modelling and experimental measurements. This paper presents some 3-D Reynolds Averaged Navier-Stokes (RANS) calculations for a volute with a trapezoidal cross-sectional shape. Flow recirculation under the ‘tongue’ and treatment of radial outflow boundary condition are two important aspects of the current calculations. The results are compared with available experimental data and the reasons for the discrepancies are discussed. The flow features highlight the fact that very strong secondary velocities are present and hence the conventional one-dimensional analyses are not adequate for design purposes. The paper also highlights the typical problems faced by a numerical analyst from grid generation point of view and briefly describes a procedure for handling the problems. Generated grids for two different volutes are presented here in order to show the capability of the grid generation method.
Aerodynamic Loss Increase due to Individual Film Cooling Injections From Gas Turbine Nozzle Surface
Authors: Kubo Ryo , Otomo Fumio , Fukuyama Yoshitaka , Nakata Yuhji
Published: December 2014

A CFD investigation was conducted on the total pressure loss variation for a linear nozzle guide vane cascade of a gas turbine, due to the individual film injections from the leading edge shower head, the suction surface, the pressure surface and the trailing edge slot. The results were compared with those of low speed wind tunnel experiments.

A 2-D Navier-Stokes procedure for a 2-D slot injection, which approximated a row of discrete film holes, was performed to clarify the applicable limitation in the pressure loss prediction during an aerodynamic design stage, instead of a costly 3-D procedure for the row of discrete holes.

In mass flow rate ratios of injection to main flow from 0% to 1%, the losses computed by the 2-D procedure agreed well with the experimental losses except for the pressure side injection cases. However, as the mass flow rate ratio was increased to 2.5%, the agreement became insufficient. The same tendency was observed in additional 3-D computations more closely modeling the injection hole shapes.

The summations of both experimental and computed loss increases due to individual row injections were compared with both experimental and computed loss increases due to all-row injection with the mass flow rate ratio ranging from 0% to 7%. Each summation agreed well with each all-row injection result. Agreement between experimental and calculated results was acceptable. Therefore, the loss due to all-row injections in the design stage can be obtained by the correlations of 2-D calculated losses from individual row injections. To improve more precisely the summation prediction for the losses due to the present all-row injections, extensive research on the prediction for the losses due to the pressure side injection should be carried out.
Development of ASTM Standards in Support of Advanced Ceramics — Continuing Efforts
Authors: Brinkman Charles R.
Published: December 2014

An update is presented of the activities of the American Society for Testing and Materials (ASTM) Committee C-28 on Advanced Ceramics. Since its inception in 1986, this committee, which has five standard producing subcommittees, has written and published over 32 consensus standards. These standards are concerned with mechanical testing of monolithic and composite ceramics, nondestructive examination, statistical analysis and design, powder characterization, quantitative microscopy, fractography, and terminology. These standards ensure optimum material behavior with physical and mechanical property reproducibility, component reliability, and well-defined methods of data treatment and material analysis for both monolithic and composite materials. Committee C-28 continues to sponsor technical symposia and to cooperate in the development of international standards. An update of recent and current activities as well as possible new areas of standardization work will be presented.
Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries
Authors: Day Charles R. B. , Oldfield Martin L. G. , Lock Gary D. , Dancer Stephen N.
Published: December 2014

This paper further extends the research reported by Day et al. (1997), which reported aerodynamic efficiency measurements on an annular cascade of engine representative transonic nozzle guide vanes with extensive film cooling.

This work compares the measured aerodynamic efficiencies of blades with 14 rows of cylindrical cooling holes with a new geometry in which 8 of the rows have been replaced by holes having a fan-shaped exit geometry. The effects of adding trailing edge slot ejection are also presented. By selectively blocking rows of holes, the cumulative effect on the mid-span efficiency of adding rows of cooling holes has also been determined.

A dense foreign gas (SF6/Ar mixture) is used to simulate engine representative coolant-to-mainstream density ratios, momentum ratios and blowing rates under ambient temperature conditions. The flowfield measurements have been obtained using a four-hole pyramid probe in a short duration blowdown facility which correctly models engine Reynolds and Mach numbers, as well as the inlet turbulence intensity.

Experimental results are presented as area traverse maps (total pressure, isentropic Mach number and flow angles), from which the incremental changes in efficiency due to film cooling have been calculated. The effects of different assumptions for the coolant total pressure are shown. Experimental data agrees reasonably well with loss predictions using a Hartsel model.
PIV Investigation of the Flow Characteristics in an Internal Coolant Passage With Two Ducts Connected by a Sharp 180° Bend
Authors: Schabacker J. , Bölcs A. , Johnson B. V.
Published: December 2014

A PIV study of the flow in a stationary model of a smooth two-pass internal coolant passage is presented, which focuses on the flow characteristics in the sharp 180° bend and downstream of the bend where the flow is redeveloping. Because PIV in its traditional conception only allows for the investigation of two-dimensional flow, a stereoscopic digital PIV system was assembled that measures all three velocity components simultaneously. The mean-velocity field and turbulence quantities of the flow are obtained from the PIV measurements.

The model of the coolant passage consists of two square ducts, each having a length of 19 hydraulic diameters, which are connected by a sharp 180° bend with a rectangular outer wall. The measurements were obtained at one flow condition with a flow Reynolds number of 50,000. A strong secondary flow motion occurs in the bend of the smooth passage that consists of two counter rotating vortices, which impinge on the outer wall and influence the flow in the downstream leg. Both of the outer corners contain regions of recirculating flow. A separation bubble, about 1.5 hydraulic diameters long, occurs on the inner wall of the return pass. In the symmetry plane, the flow recovers from the bend effect within 10 hydraulic diameters.
Aeropropulsion Environmental Test Facility
Authors: Lominac John K. , Boytos Joseph F.
Published: December 2014

As part of the DoD Base Realignment and Closure process, the unique Navy capability to test aircraft engines under various environmental conditions is being transitioned to the Air Force. A new facility, using two modified sea-level Air Force T-9 test cells as building blocks, formed the basis of the new design. The structural design of the test cells and test control building was based on the aerodynamic and acoustic requirements for testing large afterburning turbojet/turbofan engines. Major construction has passed the 90-percent completion milestone. Aerodynamic criteria were defined in 1/12th-scale model tests of an engine installation using an F110 engine simulator. Modifications were then made to the basic T-9 test cells to allow ram air duct direct-connect capability. Following construction, activation/validation of the test facility will be conducted with an actual F110 engine, run in both direct-connect and bellmouth inlet configurations. Initial Operational Capability is scheduled for September 1998. Technical aspects of the facility design, construction, and ram air duct are described. Final system capabilities are airflow of 249.48 kg/sec; inlet air temperature range of 219 to 503 K; and inlet air pressures up to 206.85 kPa (1.1 Mach number). Environmental conditions of high and low temperature, water and ice ingestion, sand ingestion, and salt air corrosion can be duplicated. Engine transient operation, and mission profile endurance tests with simulated inlet conditions of forward flight velocities will be available to both government and industry users.
A New Test Facility for Testing of Cooled Gasturbine Components
Authors: Rådeklint Ulf R. , Hjalmarsson Christer S.
Published: December 2014

A high pressure hot test facility for cooled gas turbine components has been developed for use in turbine cooling research. In this facility, heat transfer tests for a sector of real turbine vanes can be performed under continuous operation. The heat transfer tests are performed at an operating point that is scaled down from the real engine operating point. The compressor can deliver air at the rate of up to 10 kg/s at 20 bars. Air temperatures of up to 1170 K can be achieved by using an oil-fired combustor. Besides conventional instrumentation such as thermocouples and pressure probes, the facility is equipped with an IR-camera to map two-dimensional wall temperature fields. Hot wire anemometry and an LDV system are used to determine mean and fluctuating velocity components.

This paper describes design and performance of the test facility as well as the control and measurement equipment. The test and evaluation procedures used for testing of cooled gas turbine vanes are also presented.
Economic Considerations in the Development of New Repairs for Gas Turbines
Authors: Picton Paul J.
Published: December 2014

The economic concerns of developing a new repair procedure for a gas turbine for commercial production can be more challenging to overcome than the technical concerns. New repairs face a wide variety of economic and technical issues that branch into all phases of an operation. Coordination of a repair requires cooperation between engineering, production, finance, customer service, marketing, regulatory agencies, materials/purchasing, and senior management. A complete financial analysis of both internal and external expectations is required for a fiscally responsible project. This paper will examine the economic consideration underlying repair development and will include a discussion of the interaction and interests between the various functional groups.
Turbine Blade Aerodynamic Wall Shear Stress Measurements and Predictions
Authors: Fitzgerald J. E. , Niven A. J. , Davies M. R. D.
Published: December 2014

The correct prediction of the aerodynamic wall shear stress is a good test of a numerical codes ability to predict profile loss. Its measurement with heated thin film gauges is significantly easier than attempting a complete measurement of a turbine blade boundary layer. A modified form of previously published heated thin film gauge calibrations allow wall shear stress measurement in laminar incompressible flow with favourable pressure gradients and turbulent incompressible flows with small pressure gradients. In this paper, measurements are presented of the distribution of aerodynamic wall shear stress over the suction surface of a turbine blade in a linear cascade. Gauge voltage signal analyses show a laminar separation bubble between about 53% and 63% of suction surface length that is confirmed by surface flow visualisation. By-pass transition is detected by downstream gauges. Wall shear stress measurements are presented at two cascade incidence angles and for tripped and natural transition. The commercial code FLUENT is used to predict the surface pressure distribution, the aerodynamic wall shear stress distribution in the laminar region and the turbulent surface shear distribution for the tripped boundary layer. Comparisons are made between measurements and predictions.
Time Resolved HWA Measurements of the OTL Flow Field From a Shrouded Turbine HP Rotor Blade
Authors: Taylor Mark D. , De Pablos Tahiche , Rose Martin G.
Published: December 2014

Detailed time resolved Hot Wire Anemometry (HWA) measurement have been made of the over tip leakage (OTL) flow field, from a shrouded HP rotor blade. The objective of this study being to investigate the sensitivity of the flow conditions presented to the IP Nozzle Guide Vane (IPNGV), resulting from changes to the HP blade tip gap clearance and shroud geometry. An extensive experimental data set has been produced in the outer 25% of the annulus height. Post-processing of this data has allowed both the absolute & rotor relative velocity and whirl angle to be calculated, which has been presented in both a graphical and semi-animated form. A detailed analysis of the flow field has been undertaken, which has been compared with the exit flow field predicted by a comprehensive CFD simulation of the HP blade and shroud. Good agreement between the measured and the predicted flow field has been obtained. This has permitted the salient features, which influence the flow conditions presented to the IPNGV, to be identified. Advanced post-processing of the time-resolved data, has enabled some of the Reynolds and Deterministic stress components to be evaluated. A comparison of the magnitude of these components has been made, which the objective of assessing their relative importance in multistage steady CFD calculations.
Dynamic Flame Structure in a Low NOx Premixed Combustor
Authors: Anderson Torger J. , Sowa William A. , Morford Stephen A.
Published: December 2014

Flame emittance images phase-locked to acoustic fluctuations have been acquired to study flame structure variations in lean premixed gas-fueled swirl-stabilized combustor systems used in industrial gas turbines. Images have been acquired through a specially-designed optical probe that makes use of the limited optical access typical of these combustors. A number of observations appear to be consistent under widely varying operating conditions. While flame stabilization was anticipated in the central vortex and outer recirculation zone of the nozzle, no optical emissions have been observed in the outer region. Oscillations in the flame emittance appear to be primarily in intensity rather than structure suggesting that the major contributor to acoustic coupling may be equivalence ratio variations rather than the motions of large scale fluid structures.
On the Effect of Single Mode Bending/Torsion Coupling on the Flutter Behavior in a Transonic Fan
Authors: Isomura Kousuke
Published: December 2014

The effect of the coupling of the torsion mode blade vibration to the bending mode flutter in transonic fans has been studied by quasi-3D viscous unsteady calculations. The type of flutter in this research is that of a highly loaded blade with a tip relative Mach number just above unity, for which the mechanism is that the instability of the passage shock wave when it unstarts generates the dominant blade exciting aerodynamic work at its foot on the pressure surface of the blade. The dependence of such flutter on the blade vibration mode, i.e. the amplitude ratio and the phase difference of the bending and torsional components has been studied.

The study showed that the blade exciting aerodynamic work reduced when the torsional component is added in-phase (torsional motion noses up during the upward bending motion) to the bending oscillation. The amplitude of the torsional component was shown to have an optimum amplitude.

It was also shown that this tendency would switch when the shock wave is fully detached, and the blade exciting aerodynamic work would increase by adding the torsional component in-phase to the bending oscillation.
Flutter Mechanisms in Low Pressure Turbine Blades
Authors: Nowinski M. , Panovsky J.
Published: December 2014

The work described in this paper is part of a comprehensive research effort aimed at eliminating the occurrence of low pressure turbine blade flutter in aircraft engines. The results of fundamental unsteady aerodynamic experiments conducted in an annular cascade are studied in order to improve the overall understanding of the flutter mechanism and to identify the key flutter parameters. In addition to the standard traveling wave tests, several other unique experiments are described. The influence coefficient technique is experimentally verified for this class of blades. The beneficial stabilizing effect of mistuning is also directly demonstrated. Finally, the key design parameters for flutter in low pressure turbine blades are identified. In addition to the experimental effort, correlating analyses utilizing linearized Euler methods demonstrate that these computational techniques are adequate to predict turbine flutter.
Applications of an Inviscid Q3D Linearized Flow Solver Towards the High Operating Line Flutter Region of a Transonic Fan
Authors: Börjesson Tomas J. , Fransson Torsten H.
Published: December 2014

The capabilities of an inviscid quasi three-dimensional linearized unstructured flow solver to correctly predict the stall flutter limit, flutter modes and critical inter-blade phase angles on a transonic rotating shroudless fan model where experimental data exist have been investigated. Three operating points were chosen for investigation at 70% and 95% speed. At 70% speed two points were investigated: one close to the torsional flutter boundary (at the intermediate operating line) and one at the flutter boundary. The 95% speed point was at the flexural flutter boundary. Steady state and unsteady calculations were made at several stream sections per operating point. At each stream section unsteady calculations were performed over the entire range of inter-blade phase angles with different mode shapes (real mode, rigid torsion and rigid bending) at different frequencies. Thus the model was “provoked” with “unphysical” mode shapes and frequencies to be compared to the unsteady solution obtained with the mode shapes and frequencies observed from the experiments. Furthermore all unsteady calculations were made with different mesh densities and solutions from different “tuned” and “untuned” steady-state solutions.

The main conclusion of the validation of the inviscid Q3D Euler model on the Fan C Model Rotating Rig is that the model generally predicts flutter, flutter modes and the critical inter-blade phase angles to be close to the experimentally determined ones.
Identification of Mistuning Characteristics of Bladed Disks From Free Response Data
Authors: Mignolet Marc 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. Two 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”. The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
Modification and Redesign of GT Components
Authors: Basu Rahul D.
Published: December 2014

Description: Stress analysis of a GT engine fan shaft was performed for IN718 and Ti. A FE package NISA gave stiffness for unit radial and tangential loads. Results obtained with IN718 were compared with an earlier study by SNECMA. An extension of the study for weight reduction was done with Ti material parameters. The design was adapted to simplify a spring bearing mount for the HP (#3) bearing.

A convoluted spring bearing mount suggested by SNECMA was redesigned using the results for the conical fan shaft to give a more gradual stress distribution. Such a structure would be less likely to yield in LCF and catastrophic failure modes. Comparison between computed results and tabulated results for conical shells was attempted.

Results depended on loading and point of application and mounting. For instance, the fan shaft was fixed on the main rotor and a force applied to the rim and vice versa. Variation in the number of nodes and order of approximation also affected the results. Regions of maximum stress were shown in contour plots, while displacement studies gave modes of deflection.
Leakage Effects in the Rotor Tip-Clearance Region of a Multistage Axial Compressor: Part 2 — Numerical Modelling
Authors: Politis E. S. , Giannakoglou K. C. , Papailiou K. D.
Published: December 2014

Innovative measurements of tip-clearance flow for the 3rd stage rotor embedded in a four stage Low-Speed Research Compressor are presented in the companion ASME paper. Here, in Part 2, the rotor flow is numerically simulated through a Navier-Stokes solver implementing the k-ε turbulence model. The 3rd stage rows are considered as discrete parts of the same computational domain and the flow in each one of them is treated as steady in the corresponding system of reference. An iterative, though loose, coupling between the rotor exit and the stator inlet is established by artificially increasing the inter-row distance. To model tip-clearance flow effects with sufficient accuracy, a two-block grid system per row is used. Comparisons with measurements published in Part 1 for the average flow quantities at the exit of both rows are presented. Row patterns close to the rotor tip-clearance region are illustrated.
Flashback Arrestor for Lean Premixed, Prevaporized, Low NOx Combustors
Authors: Kraemer Gil , Lee Chi-Ming
Published: December 2014

Lean premixed, prevaporized (LPP) high temperature combustor designs as explored for Advanced Subsonic Transport (AST) and High Speed Civil Transport (HSCT) combustors can achieve low NOx emission levels. An enabling device is needed to arrest flashback and inhibit autoignition at high power conditions and during transients (surge and rapid spool down). A novel flashback arrestor design has demonstrated the ability to arrest flashback and inhibit downstream flame holding in a 4.6 cm diameter tubular reactor at full power inlet temperatures (725 °C) using Jet-A fuel at 0.4 ≤ ϕ ≤ 3.5. Several low pressure loss (0.2% to 0.4% at 30 m/s) flashback arrestor designs were developed which arrested flashback at all of the test conditions. Flame holding was also inhibited off the flash arrestor face or within the downstream tube at low velocities (≤ 3 to 6 m/s), thus protecting the flashback arrestor and combustor premixer components. Upstream flow conditions influence the specific configuration based on using either a 45% or 76% upstream geometric blockage. Stationary, lean premixed dry low NOx gas turbine combustors would also benefit from this low pressure drop flashback arrestor design which can be easily integrated into new and existing designs.
Gallium codoping for high visible and near-infrared transmission in Al-doped ZnO thin films for industrial-scale applications
Authors: Park Ji Hun , Shin Sang Ho , Yoon Hyung Seok , Jeon Yongbae , Lee Seunghun , Lee Yoongyu , Yoon Sangwon
Published: December 2014

Transparent conductive oxide (TCO) materials have been constantly studied and developed in laboratory research scale, but few of them were successfully connected to the industrial production. One of main reasons is a lack of reproducibility of the high TCO performance due to the completely different fabrication conditions, equipment, and scale between academic science and industry. In this work, the authors report high visible and near-infrared transmission in Zn(Al,Ga)O thin films that were fabricated under suitable industrial conditions by using a large-scale, high-throughput in-line sputtering system. Zn(Al,Ga)O exhibits sheet resistance of ∼8.05 Ω/sq. and average optical transmittance of 92.07% in the visible region, with a figure of merit that is three times higher than that of ZnAlO. Zn(Al,Ga)O also shows high near-infrared transmittance tunability of more than 10% without significant change in the visible light transmittance, where the difference is <1%. The authors reveal the significant roles of Ga in both compensating for the degradation in the film crystallinity and suppressing the creation of crystal defects such as Al interstitials, ZnAl2O4 nanocluster precipitations, and grain boundaries. These results suggest high optoelectrical properties of Zn(Al,Ga)O thin film for industrial applications.
Multienergy CT acquisition and reconstruction with a stepped tube potential scan
Authors: Shen Le , Xing Yuxiang
Published: December 2014

Purpose:

Based on an energy‐dependent property of matter, one may obtain a pseudomonochromatic attenuation map, a material composition image, an electron‐density distribution, and an atomic number image using a dual‐ or multienergy computed tomography (CT) scan. Dual‐ and multienergy CT scans broaden the potential of x‐ray CT imaging. The development of such systems is very useful in both medical and industrial investigations. In this paper, the authors propose a new dual‐ and multienergy CT system design (segmental multienergy CT, SegMECT) using an innovative scanning scheme that is conveniently implemented on a conventional single‐energy CT system. The two‐step‐energy dual‐energy CT can be regarded as a special case of SegMECT. A special reconstruction method is proposed to support SegMECT.

Methods:

In their SegMECT, a circular trajectory in a CT scan is angularly divided into several arcs. The x‐ray source is set to a different tube voltage for each arc of the trajectory. Thus, the authors only need to make a few step changes to the x‐ray energy during the scan to complete a multienergy data acquisition. With such a data set, the image reconstruction might suffer from severe limited‐angle artifacts if using conventional reconstruction methods. To solve the problem, they present a new prior‐image‐based reconstruction technique using a total variance norm of a quotient image constraint. On the one hand, the prior extracts structural information from all of the projection data. On the other hand, the effect from a possibly imprecise intensity level of the prior can be mitigated by minimizing the total variance of a quotient image.

Results:

The authors present a new scheme for a SegMECT configuration and establish a reconstruction method for such a system. Both numerical simulation and a practical phantom experiment are conducted to validate the proposed reconstruction method and the effectiveness of the system design. The results demonstrate that the proposed SegMECT can provide both attenuation images and material decomposition images of reasonable image quality. Compared to existing methods, the new system configuration demonstrates advantages in simplicity of implementation, system cost, and dose control.

Conclusions:

This proposed SegMECT imaging approach has great potential for practical applications. It can be readily realized on a conventional CT system.
Markerless motion tracking of lung tumors using dual‐energy fluoroscopy
Authors: Patel Rakesh , Panfil Joshua , Campana Maria , Block Alec M. , Harkenrider Matthew M. , Surucu Murat , Roeske John C.
Published: December 2014

Purpose:

To evaluate the efficacy of dual‐energy (DE) vs single‐energy (SE) fluoroscopic imaging of lung tumors using a markerless template‐based tracking algorithm.

Methods:

Ten representative patient breathing patterns were programmed into a Quasar™ motion phantom. The phantom was modified by affixing pork ribs to the surface, and a cedar insert with a small spherical volume was used to simulate lung and tumor, respectively. Sequential 60 kVp (6 mA) and 120 kVp (1.5 mA) fluoroscopic sequences were acquired. Frame‐by‐frame weighted logarithmic subtraction was performed resulting in a DE fluoroscopic sequence. A template‐based algorithm was then used to track tumor motion throughout the DE and SE fluoroscopy sequences. Tracking coordinates were evaluated against ground‐truth tumor locations. Fluoroscopic images were also acquired for two lung cancer patients, neither of which had implanted fiducials.

Results:

For phantom imaging, a total of 1925 frames were analyzed. The algorithm successfully tracked the target on 99.9% (1923/1925) of DE frames vs 90.7% (1745/1925) SE images (p < 0.01). The displacement between tracking coordinates and ground truth for the phantom was 1.4 mm ± 1.1 mm for DE vs 2.0 mm ± 1.3 mm for SE (p < 0.01). Images from two patients, one with a larger tumor and one with a smaller tumor, were also analyzed. For the patient with the larger tumor, the average displacement from physician defined ground truth was 1.2 mm ± 0.6 mm for DE vs 1.4 mm ± 0.7 mm for SE (p = 0.016). For the patient that presented with a smaller tumor, the average displacement from physician defined ground truth was 2.2 mm ± 1.0 mm for DE vs 3.2 mm ± 1.4 mm for SE (p < 0.01). Importantly, for this single patient with the smaller tumor, 15.6% of the SE frames had >5 mm displacements from the ground truth vs 0% for DE fluoroscopy.

Conclusions:

This work indicates the potential for markerless tumor tracking utilizing DE fluoroscopy. With DE imaging, the algorithm showed improved detectability vs SE fluoroscopy and was able to accurately track the tumor in nearly all cases.
Systematic identification of signaling pathways with potential to confer anticancer drug resistance
Authors: Martz Colin A. , Ottina Kathleen A. , Singleton Katherine R. , Jasper Jeff S. , Wardell Suzanne E. , Peraza-Penton Ashley , Anderson Gray R. , Winter Peter S. , Wang Tim , Alley Holly M. , Kwong Lawrence N. , Cooper Zachary A. , Tetzlaff Michael , Chen Pei-Ling , Rathmell Jeffrey C. , Flaherty Keith T. , Wargo Jennifer A. , McDonnell Donald P. , Sabatini David M. , Wood Kris C.
Published: December 2014

Pathway-centric screening reveals new mechanisms of drug resistance and combination therapeutic strategies.
Pharmacokinetics and Pharmacodynamics of Multiple-Dose Intravenous Nemonoxacin in Healthy Chinese Volunteers
Authors: Wu Xiao-jie , Zhang Jing , Guo Bei-ning , Zhang Ying-yuan , Yu Ji-cheng , Cao Guo-ying , Chen Yuan-cheng , Zhu De-mei , Ye Xin-yu , Wu Ju-fang , Shi Yao-guo , Chang Li-wen , Chang Yu-ting , Tsai Cheng-yuan
Published: December 2014

This study evaluated the safety and pharmacokinetic/pharmacodynamic profiles of nemonoxacin in healthy Chinese volunteers following multiple-dose intravenous infusion once daily for 10 consecutive days. The study was composed of two stages. In the open-label stage, 500 mg or 750 mg of nemonoxacin (
n =
12 each) was administered at an infusion rate of 5.56 mg/min. In the second stage, with a randomized double-blind placebo-controlled design, 500, 650, or 750 mg of nemonoxacin (
n =
16 in each cohort; 12 subjects received the drug and the other 4 subjects received the placebo) was given at an infusion rate of 4.17 mg/min. The results showed that, in the first stage, the maximal nemonoxacin concentrations (mean ± SD) at steady state (
C
max_ss
) were 9.60 ± 1.84 and 11.04 ± 2.18 μg/ml in the 500-mg and 750-mg cohorts, respectively; the areas under the concentration-time curve at steady state (AUC
0–24_ss
) were 44.03 ± 8.62 and 65.82 ± 10.78 μg · h/ml in the 500-mg and 750-mg cohorts, respectively. In the second stage, the nemonoxacin
C
max_ss
values were 7.13 ± 1.47, 8.17 ± 1.76, and 9.96 ± 2.23 μg/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively; the AUC
0–24_ss
values were 40.46 ± 9.52, 54.17 ± 12.10, and 71.34 ± 17.79 μg · h/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively. No accumulation was found after the 10-day infusion with any regimen. The drug was well tolerated. A Monte Carlo simulation indicated that the cumulative fraction of response of any dosing regimen was nearly 100% against
Streptococcus pneumoniae
. The probability of target attainment of nemonoxacin therapy was >98% when the MIC of nemonoxacin against
S. pneumoniae
was ≤1 mg/liter. It is suggested that all of the studied intravenous nemonoxacin dosing regimens should have favorable clinical and microbiological efficacies in future clinical studies. (This study has been registered at
ClinicalTrials.gov
under registration no. NCT01944774.)
Effects of the Global Regulator CsrA on the BarA/UvrY Two-Component Signaling System
Authors: Camacho Martha I. , Alvarez Adrian F. , Gonzalez Chavez Ricardo , Romeo Tony , Merino Enrique , Georgellis Dimitris
Published: December 2014

The hybrid sensor kinase BarA and its cognate response regulator UvrY, members of the two-component signal transduction family, activate transcription of CsrB and CsrC noncoding RNAs. These two small RNAs act by sequestering the RNA binding protein CsrA, which posttranscriptionally regulates translation and/or stability of its target mRNAs. Here, we provide evidence that CsrA positively affects, although indirectly,
uvrY
expression, at both the transcriptional and translational levels. We also demonstrate that CsrA is required for properly switching BarA from its phosphatase to its kinase activity. Thus, the existence of a feedback loop mechanism that involves the Csr and BarA/UvrY global regulatory systems is exposed.
Physiology and Substrate Specificity of Two Closely Related Amino Acid Transporters, SerP1 and SerP2, of Lactococcus lactis
Authors: Noens Elke E. E. , Lolkema Juke S.
Published: December 2014

The
serP1
and
serP2
genes found adjacently on the chromosome of
Lactococcus lactis
strains encode two members of the amino acid-polyamine-organocation (APC) superfamily of secondary transporters that share 61% sequence identity. SerP1 transports
l
-serine,
l
-threonine, and
l
-cysteine with high affinity. Affinity constants (

K
m

) are in the 20 to 40 μM range. SerP2 is a
dl
-alanine/
dl
-serine/glycine transporter. The preferred substrate appears to be
dl
-alanine for which the affinities were found to be 38 and 20 μM for the
d
and
l
isomers, respectively. The common substrate
l
-serine is a high-affinity substrate of SerP1 and a low-affinity substrate of SerP2 with affinity constants of 18 and 356 μM, respectively. Growth experiments demonstrate that SerP1 is the main
l
-serine transporter responsible for optimal growth in media containing free amino acids as the sole source of amino acids. SerP2 is able to replace SerP1 in this role only in medium lacking the high-affinity substrates
l
-alanine and glycine. SerP2 plays an adverse role for the cell by being solely responsible for the uptake of toxic
d
-serine. The main function of SerP2 is in cell wall biosynthesis through the uptake of
d
-alanine, an essential precursor in peptidoglycan synthesis. SerP2 has overlapping substrate specificity and shares 42% sequence identity with CycA of
Escherichia coli
, a transporter whose involvement in peptidoglycan synthesis is well established. No evidence was obtained for a role of SerP1 and SerP2 in the excretion of excess amino acids during growth of
L. lactis
on protein/peptide-rich media.
The efficacy and safety of different anticoagulants on patients with severe sepsis and derangement of coagulation: a protocol for network meta-analysis of randomised controlled trials
Authors: Jiang Libing , Jiang Shouyin , Feng Xia , Ma Yuefeng , Zhang Mao
Published: December 2014

Introduction

Sepsis is the leading cause of mortality in non-cardiological critically ill patients. There are as many as 20 million cases of sepsis annually worldwide, with a mortality rate of around 35%. It has been reported that the dysregulation of haemostatic system due to the interaction between coagulation system and inflammatory response is a strong predictor of mortality in patients with severe sepsis. In this context, several anticoagulants have been evaluated in recent years. However, the results of these studies were inconsistent and even contradictory. In addition, there is insufficient evidence comparing the efficacy and safety of different anticoagulants. The purpose of our study is to carry out a systematic review and network meta-analysis comparing the efficacy and safety of different anticoagulants for severe sepsis based on existing randomised controlled trials (RCTs) and ranking these anticoagulants for practical consideration.

Methods and analysis

PubMed, EMBASE and Cochrane Library databases will be systematically searched for eligible studies. Randomised controlled trials (RCT) on anticoagulant therapy for severe sepsis with multiple outcome measures will be included. The Cochrane Risk of Bias Tool will be used to assess the quality of included studies. The primary outcomes are mortality and bleeding events. The secondary outcomes include the length of intensive care stay, the length of hospital stay and duration of mechanical ventilation. Direct pairwise meta-analysis (DMA), indirect treatment comparison meta-analysis (ITC) and network meta-analysis (NMA) will be conducted to compare different anticoagulants.

Ethics and dissemination

Ethical approval is not required given that this is a protocol for a systematic review. The protocol of this systematic review will be disseminated in a peer-reviewed journal and presented at a relevant conference.

Trial registration number

This protocol has been registered in PROSPERO (http://www.crd.york.ac.uk/PROSPERO/) under registration number CRD42014013886.
Non-Abelian moduli on domain walls
Authors: Kurianovych E. , Shifman M.
Published: December 2014

We study a simple model supporting domain walls which possess two orientational moduli in addition to the conventional translational modulus. This model is conceptually close to Witten's cosmic strings. We observe an O(3) sigma model on the wall worldvolume in the low-energy limit. We solve (numerically) classical static equations of motion and find the wall profile functions and the value of the coupling of the O(3) model in terms of the bulk parameters. In the second part a term describing a spin-orbit interaction in the bulk is added, which gives rise to an entanglement between rotational and translational moduli. The corresponding extra term in the low-energy Lagrangian is calculated.
Inconsistency Detection in Multilingual Knowledge Sharing
Authors: Pariyar Amit , Murakami Yohei , Lin Donghui , Ishida Toru
Published: December 2014

Multilingual knowledge sharing imposes new requirements on knowledge management systems so as to present digital knowledge resources in multiple languages. Knowledge sharing is degraded by inconsistencies such as contents omitted or altered in one of the languages. To resolve this issue, we present a mechanism for detecting inconsistencies in multilingual knowledge sharing. A state transition model is proposed to define the states of the multilingual contents, the set of actions, and the set of transition functions. Inconsistency detection rules are designed to represent the states of the multilingual contents and thus permit the identification of inconsistencies in knowledge sharing. The analysis of a multilingual Wikipedia article indicates that inconsistencies are present in multilingual contents generated by collaboration. In experiments, the proposed mechanism is applied to a test set of revision histories of multilingual articles; the outcome shows satisfactory results with an average precision of 88% in detecting inconsistencies and a recall of 86%. While the proposal considers only user edit actions, it can detect inconsistencies which will be useful in allowing Natural Language Processing (NLP) based systems to synchronize multilingual contents in an early phase.
Cost Effective Dynamic Concept Hierarchy Generation for Preserving Privacy
Authors: Vatsavayi Valli Kumari , Adusumalli Sri Krishna
Published: December 2014

Explosive growth of information in the Internet has raised threats for individual privacy. k-Anonymity and l-diversity are two known techniques proposed to address the threats. They use concept hierarchy tree (CHT)-based generalization/suppression. For a given attribute several CHTs can be constructed. An appropriate CHT is to be chosen for attribute anonymization to be effective. This paper discusses an on the fly approach for constructing CHT which can be used for generalization/suppression. Furthermore to improve anonymization the CHT can be dynamically adjusted for a given k value. Performance evaluation is done for the proposed approach and a comparative study is performed against known methods, k-member clustering anonymization and mondrian multi-dimensional algorithm using (1) improved on the fly hierarchy (IOTF) (Campan et al., 2011), (2) on the fly hierarchy (OTF) (Campan and Cooper, 2010), (3) hierarchy free (HF) (LeFevre et al., 2006), (4) predefined hierarchy (PH) (Iyengar, 2002) (5) CHU (Chu and Chiang, 1994) and (6) HAN (Han and Fu, 1994) methods. The metrics used for evaluation are (a) information loss, (b) discernibility metric, (c) normalized average equivalence size metric. Experimental results indicate that our approach is more effective and flexible and the utility is 12% better than IOTF, 16% better than OTF and CHU, 17% better than PH and 21% better than HAN methods when applied on mondrain multi-dimensional algorithm. Experiments are conducted on k-member clustering technique and it is observed that our approach improved utility 1% better than IOTF, 2% better than OTF, 3% better than CHU, 5% better than PH and 14% better than HAN methods.
PERFORMANCE EVALUATION OF PARALLEL GENETIC AND PARTICLE SWARM OPTIMIZATION ALGORITHMS WITHIN THE MULTICORE ARCHITECTURE
Authors: RADHAMANI A. S. , BABURAJ E.
Published: December 2014

In recent studies we found that there are many optimization methods presented for multicore processor performance optimization, however each method is suffered from limitations. Hence in this paper we presented a new method which is a combination of bacterial Foraging Particle swarm Optimization with certain constraints named as Constraint based Bacterial Foraging Particle Swarm Optimization (CBFPSO) scheduling can be effectively implemented. The proposed Constraint based Bacterial Foraging Particle Swarm Optimization (CBFPSO) scheduling for multicore architecture, which updates the velocity and position by two bacterial behaviours, i.e. reproduction and elimination dispersal. The performance of CBFPSO is compared with the simulation results of GA, and the result shows that the proposed algorithm has pretty good performance on almost all types of cores compared to GA with respect to completion time and energy consumption.
The Epidemiology of Firearm Violence in the Twenty-First Century United States
Authors: Wintemute Garen J.
Published: December 2014

This brief review summarizes the basic epidemiology of firearm violence, a large and costly public health problem in the United States for which the mortality rate has remained unchanged for more than a decade. It presents findings for the present in light of recent trends. Risk for firearm violence varies substantially across demographic subsets of the population and between states in patterns that are quite different for suicide and homicide. Suicide is far more common than homicide and its rate is increasing; the homicide rate is decreasing. As with other important health problems, most cases of fatal firearm violence arise from large but low-risk subsets of the population; risk and burden of illness are not distributed symmetrically. Compared with other industrialized nations, the United States has uniquely high mortality rates from firearm violence.