bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomass-Fired Atmospheric Gas Turbine Plant
Authors: Fesharaki M. , Moser S. , Halozan H. , Jericha H.
Published: February 2015

Considering the expected climate change biomass is one of the promising energy sources for the future; however, burning and only producing low temperature heat means wasting exergy. To utilize this renewable fuel highly efficient cogeneration plants are required. Existing small and medium sized power generation systems using gas turbines have either complicated flow sheets or problems with charging pressurized combustion chambers, which are not yet solved.

This project deals with the investigation and the development of an atmospheric biomass combustion chamber combined with an inverted gas turbine cycle followed by a steam cycle. The system consists of a combustor with a wood grate firing working at atmospheric pressure. A gas turbine expands the hot particle loaded exhaust gas with a temperature of about 800 to 1000°C from atmospheric pressure down to a pressure of about 0.35 bar. The exhaust gas of the turbine is used for operating a single-pressure steam generator, the steam is mainly utilized for power generation in a steam turbine, a part stream is used to control the gas turbine inlet temperature depending on the moisture content of the fuel. The gas outlet temperature of the steam generator is about 186°C (Fig. 1, p6) at a pressure of 0.3 bar, one part is used for preheating the air required for combustion, the other part is cooled down by water injection, whereby ashes and particles are separated. The cleaned gas is compressed to atmospheric pressure again (Moser, 1995).

Such a system can achieve an efficiency of up to 40 % in the MW electricity range using components, which are available on the market, and at the same time it demonstrates the possibility of highly efficient biomass utilization.
Thermal Efficiency Projections of a Simple-Cycle Gas Turbine in Biogas Power Generation
Authors: Yomogida David E. , Thinh Ngo D. , Tiangco Valentino M. , Lee Ying
Published: February 2015

The thermal efficiency of a 125 kW simple-cycle gas turbine for biogas power generation was estimated, using a computer code developed for simple-cycle gas turbines. The computer code can predict expected values for the thermal efficiency and specific work along with the expected temperatures and pressures at various stages in the gas turbine. For the 125 kW Solar Gas Turbine (Titan series), the projected thermal efficiency is about 14%. This paper additionally presents a sensitivity analysis oo the operating condition and design parameter which had the greatest impacts on the thermal efficiency. These results will assist the California Energy Commission in determining the type of combustion device most suitable for biogas power generation.
Status of the Development of the CGT301, a 300 KW Class Ceramic Gas Turbine
Authors: Mikami Takao , Tanaka Shinya , Tatsuzawa Masashi , Sakida Takeshi
Published: February 2015

The CGT301 ceramic gas turbine is being developed under a contract from NEDO as a part of the New Sunshine Program of MTTI to improve the performance of gas turbines for cogeneration through the replacement of hot section components with ceramic parts.

The project is conducted in three phases. The project currently in Phase 2 focuses on the development of the “primary type” ceramic gas turbine (turbine inlet temperature: 1,200°C).

CGT301 is a recuperated, single-shaft, ceramic gas turbine. The turbine is a two-stage axial flow type. The major effort has been on the development of the turbine which consists of metallic disks and inserted ceramic blades (“hybrid rotor”).

Prior to engine tests, component tests were performed on the hybrid rotor to prove the validity of the design concepts and their mechanical integrity.

The engine equipped with all ceramic components except the second stage turbine blades was tested and evaluated. The engine was operated successfully for a total of 23 hours without failure at the rated engine speed of 56,000 rpm with the turbine inlet temperature of 1,200 °C.

Further, the engine equipped with all ceramic components was successfully tested for one hour under the same conditions.

Engine testing of the “primary type” ceramic gas turbine is continuing to improve the performance and the reliability of the system for the purpose of moving forward to the development of the “pilot” ceramic gas turbine (turbine inlet temperature: 1,350 °C) as the final target of this project.

This paper summarizes the progress in the development of the CGT301 with the emphasis on the test results of the hybrid rotor.
Dynamic Modeling of Starting Aerodynamics and Stage Matching in an Axi-Centrifugal Compressor
Authors: Wilkes Kevin , O’Brien Walter F. , Owen A. Karl
Published: February 2015

A DYNamic Turbine Engine Compressor Code (DYNTECC) has been modified to model speed transients from 0–100% of compressor design speed. The impetus for this enhancement was to investigate stage matching and stalling behavior during a start sequence as compared to rotating stall events above ground idle. The model can simulate speed and throttle excursions simultaneously as well as time varying bleed flow schedules. Results of a start simulation are presented and compared to experimental data obtained from an axi-centrifugal turboshaft engine and companion compressor rig. Stage by stage comparisons reveal the front stages to be operating in or near rotating stall through most of the start sequence. The model matches the starting operating line quite well in the forward stages with deviations appearing in the rearward stages near the start bleed. Overall, the performance of the model is very promising and adds significantly to the dynamic simulation capabilities of DYNTECC.
Analyzing Gas Turbine Failures to Identify Training Shortfalls
Authors: Coward Lane Hunter , Hardin James R.
Published: February 2015

The Naval Sea Systems Command (NAVSEA) wished to improve personnel training in a way that would prevent gas turbine failures on Navy ships and thereby save maintenance dollars. To determine what areas of training could provide the most benefit, NAVSEA and the Westinghouse Machinery Technology Division (MTD) systematically reviewed all gas turbine removals in the fleet during a three year period to establish which failures were most common and which might have been prevented by better operating or maintenance training. Several independent sources of maintenance data were correlated to develop one master list of training-related removals with all available information on each. Fleet Technical Support Center (FTSC) personnel, NAVSEA’s waterfront technical representatives, were interviewed about specific failures and general maintenance problems they encounter in their daily work. By correlating all the data, a most probable root cause was assigned to each removal, and training improvements that could prevent similar failures were described for all applicable failures. The training improvements recommended could prevent approximately 36 percent of unscheduled gas turbine engine removals. This percentage varies drastically with engine model.
A Methodology for Establishing Optimal Part-Load Operation of Industrial Gas Turbines
Authors: Bozza Fabio , Tuccillo Raffaele
Published: February 2015

The authors present the application of a method for gas turbine analysis, that they have recently introduced, based upon the selection of rotating components and on the study of off-design behaviour. The paper deals with an aero-derivative gas turbine, whose operating field is evaluated by an advanced cycle calculation which takes into account the fluid-dynamic and mechanical matching of the turbomachines.

Different regulation systems are considered, like variable-geometry compressor and turbine vanes, whose effect is combined with the variations in rotational speed of the gas generator device.

The simulation model allows definition of a performance map of the gas turbine, not only in terms of mechanical output and efficiency but also of pollutant emissions, as a result of the prediction of thermal NO formation inside the combustor.

The method leads to the establishment of an optimal control and regulation strategy with respect to a prescribed objective, i.e., either for maximum in energy saving or for the best compromise between performance and emission levels. Cases are examined with reference to both mechanical energy production and combined heat and power generation.
Biomass Gasification Hot Gas Filter Testing Results
Authors: Wiant Benjamin C. , Bachovchin Dennis M. , Onischak Michael , Carty Ronald H. , Ratcliff Matthew
Published: February 2015

Westinghouse Electric Corporation, under contract to the US Department of Energy’s National Renewable Energy Laboratory, has been conducting hot gas cleanup system testing compatible with a pressurized fluidized bed gasifier and the operation of a gas turbine. The testing is in support of the US Department of Energy’s Binmass Power Program, and specifically, the Biomass Gasification Facility Demonstration in Paia, Hawaii.

The hot gas cleanup testing was conducted at the Institute of Gas Technology’s research facilities in Chicago, Illinois, using the RENUGAS® 9.1 metric ton (10 ton) per day process development unit. The initial testing began in September 1994 and concluded February 1995. Based on the results of this testing, the hot gas cleanup system’s operation is being optimized for longer duration testing to be conducted at the Biomass Gasification Facility in Hawaii.

Initial test results show that hot gas filtration of bagasse flyash/char, as well as tar and oils reduction, at gasifier operating conditions can be successfully accomplished. The results of these initial tests are summarized in this paper.
Analysis of Instability Inception in High-Speed Multi-Stage Axial-Flow Compressors
Authors: Hendricks Gavin J. , Sabnis Jayant S. , Feulner Matthew R.
Published: February 2015

A nonlinear, two-dimensional, compressible dynamic model has been developed to study rotating stall/surge inception and development in high speed, multi-stage, axial flow compressors. The flow dynamics are represented by the unsteady Euler equations, solved in each interblade row gap and inlet and exit ducts as two-dimensional domains, and in each blade passage as a one-dimensional domain. The resulting equations are solved on a computational grid. The boundary conditions between domains are represented by ideal turning coupled with empirical loss and deviation correlations. Results are presented comparing model simulations to instability inception data of an eleven stage, high pressure ratio compressor operating at part-power, and the results analyzed in the context of linear modal analysis.
Computational Prediction of Heat Transfer to Gas Turbine Nozzle Guide Vanes With Roughened Surfaces
Authors: Guo S. M. , Jones T. V. , Lock G. D. , Dancer S. N.
Published: February 2015

The local Mach number and heat transfer coefficient over the aerofoil surfaces and endwalls of a transonic gas turbine nozzle guide vane have been calculated. The computations were performed by solving the time averaged Navier-Stokes equations using a fully three-dimensional computational code (CFDS) which is well established at Rolls-Royce.

A model to predict the effects of roughness has been incorporated into CFDS and heat transfer levels have been calculated for both hydraulically smooth and transitionally rough surfaces. The roughness influences the calculations in two ways; firstly the mixing length at a certain height above the surface is increased; secondly the wall function used to reconcile the wall condition with the first grid point above the wall is also altered. The first involves a relatively straightforward shift of the origin in the van Driest damping function description, the second requires an integration of the momentum equation across the wall layer. A similar treatment applies to the energy equation.

The calculations are compared with experimental contours of heat transfer coefficient obtained using both thin film gauges and the transient liquid crystal technique. Measurements were performed using both hydraulically smooth and roughened surfaces, and at engine-representative Mach and Reynolds numbers. The heat transfer results are discussed and interpreted in terms of surface-shear flow visualisation using oil and dye techniques.
A Novel Limit Distribution for the Analysis of Randomly Mistuned Bladed Disks
Authors: Mignolet Marc P. , Lin Chung-Chih
Published: February 2015

A recently introduced perturbation technique is employed to derive a novel closed form model for the probability density function of the resonant and near-resonant, steady state amplitude of blade response in randomly mistuned disks. In its most general form, this model is shown to involve six parameters but, in the important practical case of a pure stiffness (or frequency) mistuning, only three parameters are usually sufficient to completely specify this distribution. A series of numerical examples are presented that demonstrate the extreme reliability of this three-parameter model in accurately predicting the entire probability density function of the amplitude of response, and in particular the large amplitude tail of this distribution which is the most critical effect of mistuning.
Sizing of a Gas Turbine for Repowering of Cogeneration Power Plant Ljubljana by Mathematical Optimisation
Authors: Tomšič Mihael Gabriel , Perović Olgica
Published: February 2015

The paper deals with optimal sizing of a gas turbine for repowering of cogeneration power plant Ljubljana considering possible plant operational strategy with respect to variations of electric and heat loads and energy costs. CHP plant is a main source for the Ljubljana town district heating system. Existing plant consists of two condensing steam turbines with steam extraction, back pressure turbine with steam extraction, auxiliary steam and hot water boilers for peak heat load production. This system delivers up to 111 MW into the power grid and up to 348 MW of heat. Repowering with gas turbine generator set with additionally fired heat recovery boiler is considered. For uncoupling heat and power generation a heat storage tank is assumed.

For sizing of new equipment and plant operational strategy a model based on mixed-integer linear programming was developed. Zero - one integer variables are adopted to indicate the on/off status of operation, continuous variables to indicate the operational level of each constituent equipment and an optimal solution is derived by branch and bound method.

Two prospective sizes of TG sets were tested for range of assumptions regarding power purchase tariff schedules. Different optimal operation policies resulted. The study provides background for contract negotiation and for investment decisions.
Optimisation of Bypass Fan Outlet Guide Vanes
Authors: Parry A. B.
Published: February 2015

In this paper we describe an approach for combined intake-fan-OGV-pylon interactions that can be used to optimise the OGV design. The mean flow through the fan and OGVs, which is taken to be locally two-dimensional, is prescribed for a datum configuration, and the intake distortion and pylon potential field are fed in, from upstream and downstream respectively, as small incident perturbations to a coupled fan-OGV actuator disk system. In order to optimise the OGVs we suppose that the vanes are recambered in blocks, using only a limited number of vane types. The extent of each block, and the degree of over or undercambering in each block, are used as variables within a standard multi-variable optimisation package.

Following validation of the approach, results are presented for a number of cases which show, in particular, the importance of the back effect of the fan on the perturbation field at the OGV leading edge, and the relative benefits obtained by increasing the number of vane types.
The Ammonia and Diazo Technique With CO2-Calibration for Highly Resolving and Accurate Measurement of Adiabatic Film Cooling Effectiveness With Application to a Row of Holes
Authors: Haslinger W. , Hennecke D. K.
Published: February 2015

The ammonia and diazo technique with CO2-calibration for highly resolving measurement of adiabatic film cooling effectiveness distribution has been developed and improved with respect to high accuracy.

Both parts of the technique are based on the analogy between heat and mass transfer. In the ammonia and diazo part a mixture of ammonia and air is injected through the film cooling holes. Downstream of the injection a diazo film is mounted on the experimental surface. Depending on the local ammonia concentrations along the wall the diazo film turns blue. In the CO2-calibration part carbon dioxide is used as a tracer gas. Gas samples are sucked off and analyzed, thus giving the adiabatic film cooling effectiveness at certain locations on the surface. Relating the effectiveness values to the color intensities of the diazo film at the corresponding locations a calibration curve is derived.

This calibration can be applied to the whole color distribution of the diazo film resulting in a highly resolved distribution of the adiabatic film cooling effectiveness. The scattering of the measured values along the calibration curve directly indicates the quality of the measurement.

The ammonia and diazo technique with CO2-calibration has been applied to injection through a row of holes (α = 35°, p/D = 3) in the flat wall of a wind tnnnel for different blowing rates. The results show a very good suitability of this technique, especially, but not only, if the region around the film cooling holes is of special interest.
Numerical Study of Bicomponent Droplet Vaporization in a High Pressure Environment
Authors: Stengele J. , Bauer H.-J. , Wittig S.
Published: February 2015

The understanding of multicomponent droplet evaporation in a high pressure and high temperature gas is of great importance for the design of modern gas turbine combustors, since the different volatilities of the droplet components affect strongly the vapor concentration and, therefore, the ignition and combustion process in the gas phase. Plenty of experimental and numerical research is already done to understand the droplet evaporation process. Until now, most numerical studies were carried out for single component droplets, but there is still lack of knowledge concerning evaporation of multicomponent droplets under supercritical pressures. In the study presented, the Diffusion Limit Model is applied to predict bicomponent droplet vaporization. The calculations are carried out for a stagnant droplet consisting of heptane and dodecane evaporating in a stagnant high pressure and high temperature nitrogen environment. Different temperature and pressure levels are analyzed in order to characterize their influence on the vaporization behavior. The model employed is fully transient in the liquid and the gas phase. It accounts for real gas effects, ambient gas solubility in the liquid phase, high pressure phase equilibrium and variable properties in the droplet and surrounding gas.

It is found that for high gas temperatures (T = 2000 K) the evaporation time of the bicomponent droplet decreases with higher pressures, whereas for moderate gas temperatures (T = 800 K) the lifetime of the droplet first increases and then decreases when elevating the pressure. This is comparable to numerical results conducted with single component droplets. Generally, the droplet temperature increases with higher pressures reaching finally the critical mixture temperature of the fuel components. The numerical study shows also that the same tendencies of vapor concentration at the droplet surface and vapor mass flow are observed for different pressures. Additionally, there is almost no influence of the ambient pressure on fuel composition inside the droplet during the evaporation process.
Modelling of Transonic Flow in a Rotor Blade of a Steam Turbine Stage With a High Aspect Ratio Blade
Authors: Št’astný M. , Šafařík P. , Hořejší I. , Rais M.
Published: February 2015

The paper deals with results of a model aerodynamic research of flow in regions of a steam turbine stage with relatively long blades. The flow at design conditions attains transonic velocities and is investigated experimentally in transonic wind tunnel and numerically by means of 3D Euler equations for nonstationary flow. Profile cascades of five different sections of rotor blading were tested and detail flow patterns have been obtained. The experimental data are compared with results of calculations. The study of the operational flow conditions is performed. The results prove that both the tip and the root of the rotor blading are extremely loaded and they are the decisive elements for efficient operation. The middle sections have special profile forms and their aerodynamic design and test data are presented.
Modeling of Friction Contact and its Application to the Design of Shroud Contact
Authors: Yang Been-Der , Menq Chia-Hsiang
Published: February 2015

Designers of aircraft engines frequently employ shrouds in turbine design. In this paper, a variable normal load friction force model is proposed to investigate the influence of shroud-like contact kinematics on the forced response of frictionally constrained turbine blades. Analytical criteria are formulated to predict the transitions between slick, slip, and separation of the interface so as to assess the induced friction forces. When considering cyclic loading, the induced friction forces are combined with the variable normal load so as to determine the effective stiffness and damping of the friction joint over a cycle of motion. The harmonic balance method is then used to impose the effective stiffness and damping of the friction joint on the linear structure. The solution procedure for the nonlinear response nf a two-degree-of-freedom oscillator is demonstrated. As an application, this procedure is used to study the coupling effect of two constrained forces, friction force and variable normal load, on the optimization of the shroud contact design.
An Unsteady Velocity Formulation for the Edge of the Near-Wall Region
Authors: Wilson Dennis E. , Hanford Anthony J.
Published: February 2015

A phenomenological model is presented that relates freestream turbulence to the augmentation of stagnation-point surface flux quantities. The model requires the turbulence intensity, the longitudinal scale of the turbulence, and the energy spectra as inputs for the unsteady velocity at the edge of the near-wall viscous region. The form of the edge velocity contains both pulsations of the incoming flow and oscillations of the streamline.

Incompressible results using a single fluctuating component are presented within the stagnation region of a two-dimensional cylinder. The time-averaged Froessling number is determined from the computations. These predictions are compared to existing incompressible experimental data. Additionally, the variations in the surface flux quantities with the longitudinal scale of the incoming freestream turbulence, the Reynolds number, and the freestream turbulence intensity are considered.
Laser-Doppler Velocimetry Measurements in a Cascade of Compressor Blades at Stall
Authors: Hobson Garth V. , Williams Andrew J. H. , Ganaim Rickel Humberto J.
Published: February 2015

Compressor stall was simulated in the Low Speed Cascade Wind Tunnel at the Turbopropulsion Laboratory. The test blades were of controlled-diffusion design with a solidity of 1.67, and stalling occurred at 10 degrees of incidence above the design inlet air angle. All measurements were taken at a flow Reynolds number, based on chord length, of 700 000.

Laser-sheet flow visualization techniques showed that the stalling process was unsteady and occurred over the whole cascade. Detailed laser-Doppler-velocimetry measurements over the suction side of the blades showed regions of continuous and intermittent reverse flow. The measurements of the continuous reverse flow region at the leading edge were the first data of their kind in the leading edge separation bubble. The regions of intermittent reverse flow, measured with laser Doppler velocimeter, corresponded to the flow visualization studies. Blade surface pressure measurements showed a decrease in normal force on the blade as would be expected at stall. Data is presented in a form which characterizes the unsteady positive and negative velocities about their mean, for both the continuous reverse flow regions and the intermittent reverse flow regions.
On the Practical Stability and its Application to Nonlinear Control of Surge
Authors: Lin Feng
Published: February 2015

This paper first proposes a new control strategy, stabilization on the sense of practical stability, to actively stabilize the axial compression systems regardless their instability modes. Then, the theory of practical stability is applied to analyze the practical stability of the pure surge system which is a compression system without any nonaxisymmetric disturbances that grow into rotating stall. This analysis reveals that the upper limit of the amplitude in which the system surges is determined by the nonlinearity of the compressor characteristic. Thus, a nonlinear controller is designed to control the trajectory of the pure surge system by modifying the nonlinear terms in the expression for the compressor characteristic. Numerical simulation shows that the nonlinear controller can effectively shrink the size of the trajectory of the pure surge system, and therefore stabilize the system in the sense of practical stability.
Temperature Estimation and Life Prediction of Turbine Blades Using Post Service Oxidation Measurements
Authors: Swaminathan V. P. , Allen J. M. , Touchton G. L.
Published: February 2015

The depth of internal oxidation and nitridation from the surface of the 16 cooling holes in a first-stage turbine blade was measured by optical microscopy after 32,000 hours of service. Maximum depth of penetration was 15.5 mils (0.4 mm) at the trailing edge hole. An effort was made to predict hole surface metal temperatures based on these measurements using the Arrhenius relationship between time and temperature with depth of oxidation assumed to be parabolic with time. Reasonable correlations were obtained between finite element analysis results and temperature estimates based on the oxidation measurements. In the thickest part of the airfoil, where metal temperature is minimum, intergranular cracks up to 12.6 mils (0.32 mm) in depth were found at the surface of the cooling holes. Measurable oxidation attack was only one to two mils (0.025–0.050mm). Based on an approximate elastic-relaxation-local inelastic stress analysis, it was calculated that inelastic local strains of over one percent occur at the points of cracking. No cracking was observed in the more heavily oxidized, lower stressed, hotter holes. However, cracking occurred in a trailing edge tip cooling hole when weld repair of the tip squealer was attempted, due to embrittlement and grain boundary oxidation from service exposure. Temperature estimates suitable for life assessment purposes using oxidation measurements appears to be a possible technique that should be further developed and validated.
The Travelling Cascade, Constant Volume Heat Exchanger in a Gas Turbine Lead Combined Cycle
Authors: Georgiou Demos P.
Published: February 2015

When a gas enclosed in a cavity is heated or cooled, its pressure changes with its temperature as well. If a set of two countermoving “driven” cavity cascades employs the same free wall, then the system will operate as a countercurrent heat exchanger. At the exit points of the heat exchanger the two gases can be brought back to their original (atmospheric) pressure by isentropic processes thus producing useful work. The entire set of thermodynamic processes forms a double Lenoir cycle. The exhausts from the two Lenoir cycles may drive two more sets of corresponding cycles, thus allowing for the cascading of the process, until the added useful work becomes insignificant. When this idea is employed as a bottoming cycle in a Gas Turbine lead Combined cycle, employing four sets of Lenoir cycles, the achievable total thermal efficiencies rise to the 75 to 82 % level, athough the amount of heat transferred in all these processes is about 50 % more than that in a modern Brayton-Rankine combined cycle.
Aspirating Probe Measurements of the Unsteady Total Temperature Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor
Authors: Suryavamshi N. , Lakshminarayana B. , Prato J.
Published: February 2015

The results from the area traverse measurements of the unsteady total temperature using a high response aspirating probe downstream of the second stator of a three stage axial flow compressor are presented. The measurements were conducted at the peak efficiency operating point. The unsteady total temperature data is resolved into deterministic and unresolved components. Hub and casing regions have high levels of unsteadiness and consequently high levels of mixing. These regions have significant levels of shaft resolved and unresolved unsteadiness. Comparisons are made between the total temperature and the total pressure data to examine the rotor 2 wake characteristics and the temporal variation of the stator exit flow. Isentropic efficiency calculations at the midpitch location show that there is about a 4% change in the algebraically averaged efficiency across the blades of the second rotor and if all the rotor 2 blades were behaving as a “best” blade, the improvement in efficiency would be about 1.3%. An attempt is made to create a composite flow field picture by correlating the unsteady velocity data with temperature and pressure data.
Upgrading of the Westinghouse 501FA Row 2 Vane Segment to the 501FC Design
Authors: Beiswenger James , Bonsall John , Janssen Joseph , Kizer Matthew
Published: February 2015

Early in 1995, Westinghouse decided to seize an opportunity to speed up the implementation of a design upgrade for the 501FA Row 2 vane segment. The planned upgrade of this vane segment had been in the conceptual design stage for a few months. Normally, this type of modification would be planned and implemented over many months. In order to achieve the desired performance goals and meet the customer’s delivery requirements this project would have to move very quickly. The project time frame required that from the conceptual drawing to start of production be no more than eight weeks.

To achieve the accelerated schedule, Westinghouse decided to team with the part machining suppliers to develop a game plan that allowed for true concurrent engineering. The resulting plan was to complete the part design at the same time that all the machining tooling and manufacturing process development was being completed. As a result of combining the resources of the turbine manufacturer with those of the machining vendors, it was possible to implement a complicated part upgrade in a matter of weeks not months.

By utilizing 3-D computer models to define the part configuration as well as to build the machining tools and develop the machining process, the team was able to meet the challenge. The final design was optimized for performance as well as ease of manufacturing. This paper describes the triumphs as well as some of the problems that the team encountered along the way to delivering the final engine hardware.
Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes
Authors: Al‐Affan I. A. M. , Hugtenburg R. P. , Bari D. S. , Al‐Saleh W. M. , Piliero M. , Evans S. , Al‐Hasan M. , Al‐Zughul B. , Al‐Kharouf S. , Ghaith A.
Published: February 2015

Purpose:

This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms.

Methods:

Experiments and Monte Carlo simulations were utilized to establish the possibility of using high‐Z materials to cover the concrete walls of the maze in order to reduce the dose of the scattered photons at the maze entrance. The dose of the backscattered photons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV.

Results:

It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co‐60 emissions and 70% for Cs‐137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscattered photons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%.

Conclusions:

This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.
Improved adaptive reconstruction of multichannel MR images
Authors: Ma Ya‐Jun , Liu Wentao , Zhao Xuna , Tang Weinan , Zhang Zihao , Tang Xin , Fan Yang , Li Huanjie , Gao Jia‐Hong
Published: February 2015

Purpose:

To improve adaptive reconstruction of multichannel MR images by simultaneously removing nonsmooth phase and signal‐loss imaging artifacts.

Methods:

The improved adaptive reconstruction consists of three steps: (1) modified multichannel images are first derived by dividing raw multichannel images by a reference image (i.e., a normalized single‐channel image); (2) the modified multichannel images are smoothed by a low‐pass filter; (3) adaptive spatial matched filters determined from the smoothed multichannel images are utilized to obtain multichannel combined images. Numerical simulations, as well as MRI experiments, on phantoms and human subjects are performed to evaluate and compare the effectiveness of this improved adaptive reconstruction approach against traditional coil combination methods.

Results:

Both simulation and MRI experimental results demonstrated that the proposed improved adaptive reconstruction method is able to obtain combined images with reduced nonsmooth phase and signal‐loss imaging artifacts.

Conclusions:

A novel multichannel image reconstruction method is developed that produces high quality multichannel combined images.
The evaluation of a 2D diode array in “magic phantom” for use in high dose rate brachytherapy pretreatment quality assurance
Authors: Espinoza A. , Petasecca M. , Fuduli I. , Howie A. , Bucci J. , Corde S. , Jackson M. , Lerch M. L. F. , Rosenfeld A. B.
Published: February 2015

Purpose:

High dose rate (HDR) brachytherapy is a treatment method that is used increasingly worldwide. The development of a sound quality assurance program for the verification of treatment deliveries can be challenging due to the high source activity utilized and the need for precise measurements of dwell positions and times. This paper describes the application of a novel phantom, based on a 2D 11 × 11 diode array detection system, named “magic phantom” (MPh), to accurately measure plan dwell positions and times, compare them directly to the treatment plan, determine errors in treatment delivery, and calculate absorbed dose.

Methods:

The magic phantom system was CT scanned and a 20 catheter plan was generated to simulate a nonspecific treatment scenario. This plan was delivered to the MPh and, using a custom developed software suite, the dwell positions and times were measured and compared to the plan. The original plan was also modified, with changes not disclosed to the primary authors, and measured again using the device and software to determine the modifications. A new metric, the “position–time gamma index,” was developed to quantify the quality of a treatment delivery when compared to the treatment plan. The MPh was evaluated to determine the minimum measurable dwell time and step size. The incorporation of the TG‐43U1 formalism directly into the software allows for dose calculations to be made based on the measured plan. The estimated dose distributions calculated by the software were compared to the treatment plan and to calibrated EBT3 film, using the 2D gamma analysis method.

Results:

For the original plan, the magic phantom system was capable of measuring all dwell points and dwell times and the majority were found to be within 0.93 mm and 0.25 s, respectively, from the plan. By measuring the altered plan and comparing it to the unmodified treatment plan, the use of the position–time gamma index showed that all modifications made could be readily detected. The MPh was able to measure dwell times down to 0.067 ± 0.001 s and planned dwell positions separated by 1 mm. The dose calculation carried out by the MPh software was found to be in agreement with values calculated by the treatment planning system within 0.75%. Using the 2D gamma index, the dose map of the MPh plane and measured EBT3 were found to have a pass rate of over 95% when compared to the original plan.

Conclusions:

The application of this magic phantom quality assurance system to HDR brachytherapy has demonstrated promising ability to perform the verification of treatment plans, based upon the measured dwell positions and times. The introduction of the quantitative position–time gamma index allows for direct comparison of measured parameters against the plan and could be used prior to patient treatment to ensure accurate delivery.
Budget for 2016 accentuates the practical
Authors: Mervis Jeffrey
Published: February 2015

White House proposal lifts (almost) all boats, but applied research floats to the top.
Biomedical initiatives get top billing in budget rollout
Authors: Kaiser Jocelyn , Servick Kelly
Published: February 2015

The president's 2016 budget request includes initiatives to promote personalized medicine and battle microbial resistance to antibiotics.
A classroom experiment
Authors: Mervis Jeffrey
Published: February 2015

NSF has spent $500 million to train thousands of science and math teachers. But what has that meant for kids?
Complete Genome Sequence Analysis of Echovirus 24 Associated with Hand-Foot-and-Mouth Disease in China in 2012
Authors: Bian Lian-lian , Yao Xin , Mao Qun-ying , Gao Fan , Wang Yi-ping , Ye Qiang , Zhu Feng-cai , Liang Zheng-lun
Published: February 2015

Echovirus 24 belongs to human enterovirus B species in the family
Picornaviridae
. Here, we report the whole-genome sequences of a novel complete genome sequence of a recombinant (echovirus 24) Echo 24 strain, PZ18/JS/2012, which was isolated from a patient with hand-foot-and-mouth disease in China.
Whole-Genome Sequence of Listeria monocytogenes Strains from Clinical and Environmental Samples from Varanasi, India
Authors: Soni Dharmendra K. , Singh Krishna M. , Ghosh Arpita , Chikara Surendra K. , Joshi Chaitanya G. , Dubey Suresh K.
Published: February 2015

We present here the whole-genome sequences of
Listeria monocytogenes
from Ganges River water, agricultural soil, and human clinical samples from Varanasi, India, which will be used for a comparative analysis.
Utility of Sequencing the
erm
(41) Gene in Isolates of Mycobacterium abscessus subsp. abscessus with Low and Intermediate Clarithromycin MICs
Authors: Brown-Elliott Barbara A. , Vasireddy Sruthi , Vasireddy Ravikiran , Iakhiaeva Elena , Howard Susan T. , Nash Kevin , Parodi Nicholas , Strong Anita , Gee Martha , Smith Terry , Wallace Richard J.
Published: February 2015

The
erm
(41) gene confers inducible macrolide resistance in
Mycobacterium abscessus
subsp.
abscessus
, calling into question the usefulness of macrolides for treating
M. abscessus
subsp.
abscessus
infections. With an extended incubation (14 days), isolates with MICs of ≥8 μg/ml are considered macrolide resistant by current CLSI guidelines. Our goals were to determine the incidence of macrolide susceptibility in U.S. isolates, the validity of currently accepted MIC breakpoints, and the
erm
(41) sequences associated with susceptibility. Of 349 isolates (excluding those with 23S rRNA gene mutations), 85 (24%) had clarithromycin MICs of ≤8 μg/ml. Sequencing of the
erm
(41) genes from these isolates, as well as from isolates with MICs of ≥16 μg/ml, including ATCC 19977
T
, revealed 10 sequevars. The sequence in ATCC 19977
T
was designated sequevar (type) 1; most macrolide-resistant isolates were of this type. Seven sequevars contained isolates with MICs of >16 μg/ml. The T28C substitution in
erm
(41), previously associated with macrolide susceptibility, was identified in 62 isolates (18%) comprising three sequevars, with MICs of ≤2 (80%), 4 (10%), and 8 (10%) μg/ml. No other nucleotide substitution was associated with macrolide susceptibility. We recommend that clarithromycin susceptibility breakpoints for
M. abscessus
subsp.
abscessus
be changed from ≤2 to ≤4 μg/ml and that isolates with an MIC of 8 μg/ml have repeat MIC testing or
erm
sequencing performed. Our studies suggest that macrolides are useful for treating approximately 20% of U.S. isolates of
M. abscessus
subsp.
abscessus
. Sequencing of the
erm
gene of
M. abscessus
subsp.
abscessus
will predict inducible macrolide susceptibility.
An OPTIMIZE Study Retrospective Analysis for Management of Telaprevir-Treated Hepatitis C Virus (HCV)-Infected Patients by Use of the Abbott RealTi
m
e HCV RNA Assay
Authors: Sarrazin Christoph , Dierynck Inge , Cloherty Gavin , Ghys Anne , Janssen Katrien , Luo Donghan , Witek James , Buti Maria , Picchio Gaston , De Meyer Sandra
Published: February 2015

Protease inhibitor (PI)-based response-guided triple therapies for hepatitis C virus (HCV) infection are still widely used. Noncirrhotic treatment-naive and prior relapser patients receiving telaprevir-based treatment are eligible for shorter, 24-week total therapy if HCV RNA is undetectable at both weeks 4 and 12. In this study, the concordance in HCV RNA assessments between the Roche High Pure System/Cobas TaqMan and Abbott RealTi
m
e HCV RNA assays and the impacts of different HCV RNA cutoffs on treatment outcome were evaluated. A total of 2,629 samples from 663 HCV genotype 1 patients receiving telaprevir/pegylated interferon/ribavirin in OPTIMIZE were analyzed using the High Pure System and reanalyzed using Abbott RealTi
m
e (limits of detection, 15.1 IU/ml versus 8.3 IU/ml; limits of quantification, 25 IU/ml versus 12 IU/ml, respectively). Overall, good concordance was observed between the assays. Using undetectable HCV RNA at week 4, 34% of the patients would be eligible for shorter treatment duration with Abbott RealTi
m
e versus 72% with the High Pure System. However, using <12 IU/ml for Abbott RealTi
m
e, a similar proportion (74%) would be eligible. Of the patients receiving 24-week total therapy, 87% achieved a sustained virologic response with undetectable HCV RNA by the High Pure System or <12 IU/ml by Abbott RealTi
m
e; however, 92% of the patients with undetectable HCV RNA by Abbott RealTi
m
e achieved a sustained virologic response. Using undetectable HCV RNA as the cutoff, the more sensitive Abbott RealTi
m
e assay would identify fewer patients eligible for shorter treatment than the High Pure System. Our data confirm the <12-IU/ml cutoff, as previously established in other studies of the Abbott RealTi
m
e assay, to determine eligibility for shortened PI-based HCV treatment. (The study was registered with ClinicalTrials.gov under registration no. NCT01241760.)
Global Assessment of Antimicrobial Susceptibility among Gram-Negative Organisms Collected from Pediatric Patients between 2004 and 2012: Results from the Tigecycline Evaluation and Surveillance Trial
Authors: Kehl Sue C. , Dowzicky Michael J.
Published: February 2015

The Tigecycline Evaluation and Surveillance Trial (TEST) was designed to monitor susceptibility to commonly used antimicrobial agents among important pathogens. We report here on susceptibility among Gram-negative pathogens collected globally from pediatric patients between 2004 and 2012. Antimicrobial susceptibility was determined using guidelines published by the Clinical and Laboratory Standards Institute (CLSI). Most
Enterobacteriaceae
showed high rates of susceptibility (>95%) to amikacin, tigecycline, and the carbapenems (imipenem and meropenem); 90.8% of
Acinetobacter baumannii
isolates were susceptible to minocycline, and susceptibility rates were highest in North America, Europe, and Asia/Pacific Rim. Amikacin was the most active agent against
Pseudomonas aeruginosa
(90.4% susceptibility), with susceptibility rates being highest in North America. Extended-spectrum β-lactamases (ESBLs) were reported for 11.0% of
Escherichia coli
isolates and 24.2% of
Klebsiella pneumoniae
isolates globally, with rates reaching as high as 25.7% in the Middle East and >43% in Africa and Latin America, respectively. Statistically significant (
P
< 0.01) differences in susceptibility rates were noted between pediatric age groups (1 to 5 years, 6 to 12 years, or 13 to 17 years of age), globally and in some regions, for all pathogens except
Haemophilus influenzae
. Significant (
P
< 0.01) differences were reported for all pathogens globally and in most regions, considerably more frequently, when pediatric and adult susceptibility results were compared. Amikacin, tigecycline, and the carbapenems were active
in vitro
against most Gram-negative pathogens collected from pediatric patients;
A. baumannii
and
P. aeruginosa
were susceptible to fewer antimicrobial agents. Susceptibility rates among isolates from pediatric patients were frequently different from those among isolates collected from adults.