bluuebunny/crossref_metadata_2025 huggingface dataset:
A Gaussian Process Modeling Approach for Fast Robust Design With Uncertain Inputs
Authors: Ryan Kevin M. , Kristensen Jesper , Ling You , Ghosh Sayan , Asher Isaac , Wang Liping
Published: August 2018

Many engineering design and industrial manufacturing applications are tasked with finding optimum designs while dealing with uncertainty in the design parameters. The performance or quality of the design may be sensitive to the input variation, making it difficult to optimize. Probabilistic and robust design optimization methods are used in these scenarios to find the designs that will perform best under the presence of known input uncertainty. Robust design optimization algorithms often require a two-level optimization problem (double-loop) to find a solution. The design optimization outer-loop repeatedly calls a series of inner loops that calculate uncertainty measures of the outputs. This nested optimization problem is computationally expensive and can sometimes render the task infeasible for practical engineering robust design problems. This paper details a single-level metamodel-assisted approach for probabilistic and robust design. An enhanced Gaussian Process (GP) metamodel formulation is used to provide exact values of output uncertainty in the presence of uncertain inputs. The GP model utilizes a squared-exponential kernel function and assumes normally distributed input uncertainty. These two factors together allow for an exact calculation of the first and second moments of the marginal predictive distribution. Predictions of output uncertainty are directly calculated, creating an efficient single-level robust optimization problem. We demonstrate the effectiveness of the single-level GP-assisted robust design approach on multiple engineering example problems, including a beam vibration problem, a cantilevered beam with multiple constraints, and a robust autonomous aircraft flight controller design problem. For the optimization problems investigated in this study, the single-level framework found the robust optimum with a 99.9% savings in function evaluations over the standard two-level approach.
Measurements of the Reactivity of Premixed, Stagnation, Methane-Air Flames at Gas Turbine Relevant Pressures
Authors: Versailles Philippe , Durocher Antoine , Bourque Gilles , Bergthorson Jeffrey M.
Published: August 2018

The adiabatic, unstrained, laminar flame speed, SL, is a fundamental combustion property, and a premier target for the development and validation of thermochemical mechanisms. It is one of the leading parameters determining the turbulent flame speed, the flame position in burners and combustors, and the occurrence of transient processes, such as flashback and blowout. At pressures relevant to gas turbine engines, SL is generally extracted from the continuous expansion of a spherical reaction front in a combustion bomb. However, independent measurements obtained in different types of apparatuses are required to fully constrain thermochemical mechanisms. Here, a jet-wall, stagnation burner designed for operation at gas turbine relevant conditions is presented, and used to assess the reactivity of premixed, lean-to-rich, methane-air flames at pressures up to 16 atm. One-dimensional (1D) profiles of axial velocity are obtained on the centreline axis of the jet-wall burner using Particle Tracking Velocimetry, and compared to quasi-1D flame simulations performed with a selection of thermochemical mechanisms available in the literature. Significant discrepancies are observed between the numerical and experimental data, and among the predictions of the mechanisms. This motivates further chemical modeling efforts, and implies that designers in industry must carefully select the mechanisms employed for the development of gas turbine combustors.
Floating Shock Platform Testing of a Magnetic Bearing Supported Chiller Compressor: Measurements and Simulation Results
Authors: Hawkins Lawrence , Wang Zhiyang , Nambiar Koman
Published: August 2018

Qualification shock testing has been completed for a new chilled water plant developed for the US Navy. The variable speed compressor at the heart of the chiller system includes a direct drive, high-speed permanent magnet (PM) motor, PM bias active magnetic bearings, and a backup bearing system. For MIL-S-901D shock certification, the chiller was mounted on a Navy floating shock platform (barge) and subjected to a standard sequence of four different shock impacts generated from high explosive charges from varying angles and standoff distances. The chiller was fully operational during three blasts and in standby mode for the fourth blast. In the standby mode, the shaft is de levitated and stationary on the backup bearings and the chiller secured. The backup bearing system of the motor absorbed the response to the shock impacts and the magnetic bearings subsequently recovered levitation as designed. The shock testing was simulated using a transient, nonlinear rotordynamic analysis including the magnetic bearing control and saturation features, backup bearings with resilient mounts and associated clearances, and structural dynamic models of the rotor and housing. Compressor/motor housing acceleration measured during the testing was used as the driving input into the simulation. Some rotor position data recorded during shock testing, the simulation approach and comparisons are reported and discussed.
Double Wall Cooling of a Full Coverage Effusion Plate With Main Flow Pressure Gradient, Including Internal Impingement Array Cooling
Authors: Vanga Sneha Reddy , Ren Zhong , Click Austin J. , Ligrani Phil , Liberatore Federico , Patel Rajeshriben , Srinivasan Ram , Ho Yin-Hsiang
Published: August 2018

The present study provides new effusion cooling data for both surfaces of full coverage effusion cooling plate. For the effusion cooled surface, presented are spatially-resolved distributions of surface adiabatic film cooling effectiveness, and surface heat transfer coefficients (measured using transient techniques and infrared thermography). For the impingement cooled surface, presented are spatially-resolved distributions of surface Nusselt numbers (measured using steady-state liquid crystal thermography). To produce this cool side augmentation, impingement jet arrays at different jet Reynolds numbers, from 2720 to 11100, are employed. Experimental data are given for a sparse effusion hole array, with spanwise and streamwise impingement hole spacing such that coolant jet hole centerlines are located midway between individual effusion hole entrances. Considered are initial effusion blowing ratios from 3.3 to 7.5, with subsonic, incompressible flow. The velocity of the freestream flow which is adjacent to the effusion cooled boundary layer is increasing with streamwise distance, due to a favorable streamwise pressure gradient. Such variations are provided by a main flow passage contraction ratio CR of 4. Of particular interest are effects of impingement jet Reynolds number, effusion blowing ratio, and streamwise development. Also included are comparisons of impingement jet array cooling results with: (i) results associated with cross flow supply cooling with CR = 1 and CR = 4, and (ii) results associated with impingement supply cooling with CR = 1, when the mainstream pressure gradient is near zero. Overall, the present results show that, for the same main flow Reynolds number, approximate initial blowing ratio, and streamwise location, significantly increased thermal protection is generally provided when the effusion coolant is provided by an array of impingement cooling jets, compared to a cross flow coolant supply.
Assessment of a Novel Non-Axial Counter-Rotating Compressor Concept for Aero-Engines
Authors: Dejour Quentin , Vo Huu Duc
Published: August 2018

This paper presents the first assessment of a new non-axial counter-rotating compressor concept. This concept consists of replacing the stator of a mixed-flow compressor stage or the diffuser of a centrifugal compressor stage with a counter-rotating rotor that will turn the flow back to the axial direction with much lower diffusion factor, while providing the equivalent in work of the upstream mixed-flow rotor or impeller. This concept has two advantages. First, the very high stage pressure rise means that only a single counter-rotating rotor may be required, making mechanical implementation simpler than for multi-stage axial counter-rotating compressors. Second, the replacement of the high flow turning (high loss) stator/diffuser in a non-axial stage with a low flow turning counter-rotating rotor gives the new concept potential for achieving higher efficiency than conventional non-axial compressors. As a first proof of concept, a subsonic counter-rotating mixed-flow compressor and its conventional (i.e. rotor-stator) equivalent have been designed with the intent of being implemented in a test rig. CFD simulations have been carried out for a comparative evaluation of both configurations. Results show that the counter-rotating mixed-flow compressor produces more than double the pressure rise of its conventional version with a slightly higher peak-efficiency while having a smaller axial length. Moreover, the counter-rotating configuration has a better stall margin than its conventional counterpart, for which the boundary layer separation from excessive flow turning in the stator causes early stall.
Quantifying Uncertainty of Gas Turbine Engine Models Generated Using Inverse Solution Methods
Authors: Nolen Craig , Delimont Jacob
Published: August 2018

In the current economic and political environment, there is a push for gas turbine operators to achieve higher operating efficiencies, which in turn, reduces emissions and fuel consumption. As these owners and operators seek to increase the efficiency of their machines, they are increasingly turning to physics-based performance modeling. This allows the end user to analyze machine performance, plan for performance upgrades, and evaluate use cases and operating conditions not originally envisioned by the original equipment manufacturers (OEMs). For owners/operators who do not have access to physics-based models provided by the hardware OEM or would like to evaluate modifications to legacy hardware, physics-based models may be developed using measured turbine performance data and high-level knowledge of the turbine architecture. In previous work, a physics-based performance model of an industrial gas turbine engine was created using measured plant operating data and an inverse solution method to allow off-design exploration of its performance. However, this model’s uncertainty was unknown, and knowledge of uncertainty is crucial to understanding a model’s reliability. In the present work, the model’s uncertainty in predicted performance at a particular operating point is investigated using statistical methods. Polynomial regressions of standard deviation are used alongside the performance regressions to describe the uncertainty at various operating points. These regressions are also used to visualize the variation of uncertainty across the performance map. Such knowledge of uncertainty can aid gas turbine operators in decision making with regard to the risks of off-design operation or equipment modifications.
Using Shock Control Bumps to Improve Transonic Fan/Compressor Blade Performance
Authors: John Alistair , Qin Ning , Shahpar Shahrokh
Published: August 2018

Shock control bumps can help to delay and weaken shocks, reducing loss generation and shock-induced separation and delaying stall inception for transonic turbomachinery components. The use of shock control bumps on turbomachinery blades is investigated here for the first time using 3D analysis. The aerodynamic optimisation of a modem research fan blade and a highly loaded compressor blade are carried out using shock control bumps to improve their performance. Both the efficiency and stall margin of transonic fan and compressor blades may be increased through the addition of shock control bumps to the geometry. It is shown how shock induced separation can be delayed and reduced for both cases. A significant efficiency improvement is shown for the compressor blade across its characteristic, and the stall margin of the fan blade is increased by designing bumps that reduce shock-induced separation near to stall. Adjoint surface sensitivities are used to highlight the critical regions of the blade geometries, and it is shown how adding bumps in these regions improves blade performance. Finally, the performance of the optimised geometries at conditions away from where they are designed is analysed in detail.
A Methodology for Quantifying Distortion Impacts Using a Modified Parallel Compressor Theory
Authors: Pokhrel Manish , Gladin Jonathan , Garcia Elena , Mavris Dimitri N.
Published: August 2018

Efforts to achieve NASA’s N+2 and N+3 fuel burn goals have led to various future aircraft concepts. A commonality in all these concepts is the presence of a high degree of interaction among the various disciplines involved. A tightly integrated propulsion/airframe results in distortion in the flow field around the engine annulus. Although beneficial in terms of propulsive efficiency (due to boundary layer ingestion), the impact of distortion on fan performance and operability remains in question for these concepts. As such, rapid evaluation of the impacts of distortion during the conceptual design phase is necessary to assess various concepts. This is especially important given the expansion of the design space afforded by turbo-electric and hybrid-electric distributed propulsion concepts, in which the gas turbine generator and propulsive devices can be decoupled in space.

A simple and rapid methodology to assess operability of compressors is the theory of Parallel Compressors (PC). PC theory views the compressor as two compressors in parallel, one with a uniform high Pt and the other with a uniform low Pt, both operating at the same speed and exiting to a common static pressure. The assumption of two compressors exiting at the common static pressure is not entirely true, especially when the distortion is high. In this paper, the development of a modified parallel compressor model with parametric boundary condition that can capture the impact of non-uniform inflow on fan performance is introduced and validated. Unlike classical PC model, the modified approach introduces a boundary condition dependent on the intensity of distortion (DPCP) at the Aerodynamic Interface Plane (AIP). Additionally, the concept of PC is also extended to Multi-Per Revolution (MPR) distortion.

A modeling environment which follows this methodology is created in PROOSIS, an object oriented 0-D cycle code. The model was created using the “compressor” components acting in parallel and a procedure for implementing both design mode and off-design mode solutions was created using the PROOSIS toolset. The example problem was implemented to demonstrate two capabilities — i) the ability of quantifying impacts on thrust and performance of a ducted fan propulsion system, and ii) the ability of predicting loss in stability pressure ratio. The results clearly show the ability of the tool to quantify distortion related losses.

The work described in this paper can be integrated to a Multi-Disciplinary Design and Optimization (MDAO) framework along with other disciplines and can be used to evaluate the viability of design space offered by novel aircraft configurations.
Sweeping Jet Film Cooling on a Turbine Vane
Authors: Hossain Mohammad A. , Agricola Lucas , Ameri Ali , Gregory James W. , Bons Jeffrey P.
Published: August 2018

The cooling performance of sweeping jet film cooling was studied on a turbine vane suction surface in a low-speed linear cascade wind tunnel. The sweeping jet holes consist of fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of Pd/D = 6. Infrared (IR) thermography was used to estimate the adiabatic film effectiveness at several blowing ratios and two different freestream turbulence levels (Tu = 0.3% and 6.1%). Convective heat transfer coefficient was measured by a transient IR technique, and the net heat flux benefit was calculated. The total pressure loss due to sweeping jet film cooling was characterized by traversing a total pressure probe at the exit plane of the cascade. Tests were performed with a baseline shaped hole (777-shaped hole) for comparison. The sweeping jet hole showed higher adiabatic film effectiveness than the 777-shaped hole in the near hole region. Although the unsteady sweeping action of the jet augments heat transfer, the net positive cooling benefit is higher for sweeping jet holes compared to 777 hole at particular flow conditions. The total pressure loss measurement showed a 12% increase in total pressure loss at a blowing ratio of M = 1.5 for sweeping jet hole while 777-shaped hole showed a 8% total pressure loss increase at the corresponding blowing ratio.
Application of Simplified Parametric Model to Estimate Fan Blade-Out Response
Authors: Brockett Theodore S. , Sawicki Jerzy T.
Published: August 2018

A six-degree-of-freedom non-linear model is developed using Lagrange’s equation. The model is used to estimate transient fan-stage dynamic response during a fan-blade-out event in a turbo fan engine. The coupled degrees of freedom in the model include the fan whirl in the fan plane, the torsional response of the fan and low-pressure turbines (LPTs) about the engine centerline, the radial position of the released blade fragment, and the angular rotation of the trailing blade from its free state due to acceleration of the released blade. The released blade is assumed to slide radially outward along the trailing blade without friction. The external loading applied to the system includes fan imbalance, the remaining fan blades machining away the rub strip, rubbing of the blades with the fan case, and slowly-varying torques on the low pressure (LP) spool as engine performance degrades. The machining of the abradable imparts tangential loading on the fan blades as momentum is transferred to the liberated rub strip material. After application of the initial conditions including angular positions, angular velocities, released blade fragment position, and torsional wind-up, the governing equations are integrated forward in time from the instant the blade fragment is released. A reasonable match to test data is shown. Parameters affecting the fan-system response are varied to study the impact on fan peak lateral whirl amplitude, peak LP shaft torque, and peak loading on the trailing blade. It is found that the rub strip and mass eccentricity have the strongest influence on the LP shaft torsional loading. It is found that mass eccentricity has the largest influence on peak fan whirl. It is also found that released blade mass and attachment stiffness have the largest influence on the trailing blade loading.
Experimental Investigation Into the High Altitude Relight of a Three-Cup Combustor Sector
Authors: Denton Michael J. , Tambe Samir B. , Jeng San-Mou
Published: August 2018

The altitude relight of a gas turbine combustor is an FAA and EASA regulation which dictates the successful re-ignition of an engine and its proper spool-up after an in-flight shutdown. Combustor pressure loss, ambient pressure, ambient temperature, and equivalence ratio were all studied on a full-scale, 3-cup, single-annular aviation combustor sector to create an ignition map. The flame development process was studied through the implementation of high-speed video. Testing was conducted by placing the sector horizontally upstream of an air jet ejector in a high altitude relight testing facility. Air was maintained at room temperature for varying pressure, and then the cryogenic heat exchanger was fed with liquid nitrogen to chill the air down to a limit of −50 deg F, corresponding with an altitude of 30,000 feet. Fuel was injected at constant equivalence ratios across multiple operating conditions, giving insight into the ignition map of the combustor sector. Results of testing indicated difficulty in achieving ignition at high altitudes for pressure drops greater than 2%, while low pressure drops show adequate performance. Introducing low temperatures to simulate the ambient conditions yielded a worse outcome, with all conditions having poor results except for 1%. High-speed video of the flame development process during the relight conditions across all altitudes yielded a substantial effect of the pressure drop on ignitability of the combustor. An increase in pressure drop was associated with a decrease in the likelihood of ignition success, especially at increasing altitudes. The introduction of the reduced temperature effect exacerbated this effect, further hurting ignition. High velocity regions in the combustor were detrimental to the ignition, and high area, low velocity regions aided greatly. The flame tended to settle into the corner recirculation zone and recirculate back into the center-toroidal recirculation zone (CTRZ), spreading downstream and likewise into adjacent swirl cups. These tests demonstrate the need for new combustor designs to consider adding large recirculation zones for combustor flame stability that will aid in relight requirements.
Development of ASTM Test Standards for the Mode I Interlaminar Fracture Toughness (GIc--Crack Growth Resistance) of Ceramic Matrix Composites
Authors: Abdi Frank , Ahmad Jalees , DorMohammadi Saber , Godines Cody , Gonczy Stephen , Mansour Rabih , Morscher Gregory N. , Choi Sung , Shi Jun , Ojard Greg
Published: August 2018

Ceramic matrix composite (CMC) materials are targeted for high temperature application in aircraft and power turbines, because of their low density and high-temperature thermo-mechanical properties, compared to conventional nickel super alloys. New test methods are needed for the assessment of the effects of delamination cracks on the structural integrity and life of CMC components. The ASTM C28 Fracture Toughness (Crack Growth Resistance – CGR) Working Group has drafted a standard test method for the “Mode I Interlaminar Fracture Tougness (GIc – Crack Growth Resistance) of Fiber-Reinforced Ceramic Matrix Composites (CMC) by Wedge Loading of a Double Cantilever Beam at Ambient Temperatures” The wedge loading method was developed to avoid the problems of high temperature bonding of loading blocks and hinges. The ASTM test standard details the scope, use, and application of the test method, interferences, test equipment, specimen geometry and preparation, test procedures, data interpretation and calculation, and reporting requirements for the new CMC CGR test method.
Expanding Fuel Flexibility in MHPS’ Dry Low NOx Combustor
Authors: Tada Katsuyoshi , Inoue Kei , Kawakami Tomo , Saitoh Keijiro , Tanimura Satoshi
Published: August 2018

Gas-turbine combined-cycle (GTCC) power generation is clean and efficient, and its demand will increase in the future from economic and social perspectives. Raising turbine inlet temperature is an effective way to increase combined cycle efficiency and contributes to global environmental conservation by reducing CO2 emissions and preventing global warming. However, increasing turbine inlet temperature can lead to the increase of NOx emissions, depletion of the ozone layer and generation of photochemical smog. To deal with this issue, MHPS (MITSUBISHI HITACHI POWER SYSTEMS) and MHI (MITSUBISHI HEAVY INDUSTRIES) have developed Dry Low NOx (DLN) combustion techniques for high temperature gas turbines. In addition, fuel flexibility is one of the most important features for DLN combustors to meet the requirement of the gas turbine market. MHPS and MHI have demonstrated DLN combustor fuel flexibility with natural gas (NG) fuels that have a large Wobbe Index variation, a Hydrogen-NG mixture, and crude oils.
A Scale Separation Method for Pollutant Prediction in Turbulent Flames Using Transported Scalars With Flamelet Generated Manifold (FGM) Method
Authors: Yadav Rakesh , Li Shaoping , Meeks Ellen
Published: August 2018

In this work, a scale separation method has been proposed and implemented in the framework of Flamelet Generated Manifold (FGM) model. In this approach, first a list of slow evolving species like NO, N2O etc., are identified. Then, a separate transport equation for each of these species (called FGM scalars) is solved in addition to the mixture fraction and progress variable equations. The forward and reverse reaction rates of these slow forming species are computed in two-dimensional FGM flamelets and pre-tabulated as a function of progress variable, mixture fraction and their respective variances. At run time, the pre-tabulated probability density function (PDF) averaged production rates of these FGM scalars are used, while their tabulated reverse rates are modified with a linear scaling based on the ratio of tabulated values of the FGM scalar and the prevailing values of the FGM scalars from three dimensional CFD solution. This mechanism allows the reverse rates to provide continuous feedback and respond to the slow evolution of scalar. Other than the list of selected scalars, all other species and temperature are still computed as a function of the main progress variable and mixture fraction. Since, a small set of scalars can be used to track key species, this methodology remains computationally efficient. The current approach has been implemented into commercial CFD solver, ANSYS Fluent, and has been validated for two lab scale turbulent flames, the first one is Sandia Flame D, while the second one is a lifted turbulent methane flame in vitiated co-flow. In the current work, two additional FGM scalar transport equations are solved for CO and NO and comparisons have been made against the tabulated values as well as the experimental data. It has been seen that the scale separation methodology of these scalars leads ∼10–15% improvements in the CO mass fraction, while it reduces the peak NO formation up to 4 times leading to better agreement with experimental data compared to tabulated values. The quality of predictions from the current method is also evaluated against finite rate chemistry-based model as well as reduced order NO model. It is found that the current model has consistent results, and is an improvement over current reduced order modeling approach.
A Novel Approach to Surge Control: High-Frequency Pressure Variance As an Indicator of Impending Surge in Centrifugal Compressors
Authors: Day Towler Meera , Allison Tim , Krueger Paul , Wygant Karl
Published: August 2018

This investigation studies fast-response pressure measurements as an indicator of the onset of surge in a single-stage centrifugal compressor. The objective is to determine an online monitoring approach for surge control that does not rely on surge margin relative to maps from predictions or factory testing. Fast-response pressure transducers are installed in the suction piping, inducer, diffuser, and discharge piping. A speed line is mapped, and high-speed pressure data are collected across the compressor map. The compressor is driven into surge several times to collect pressure data between during surge and between surge events. Following testing, these data are post-processed via filtration and statistical analyses. It is determined that, when taken together, the mean and range of the standard deviation of the time signal for multiple time steps can be used to determine whether the compressor’s operating point is approaching surge for the conditions tested.
OH* Chemiluminescence Imaging of the Combustion Products From a Methane-Fueled Rotating Detonation Engine
Authors: Tobias J. , Depperschmidt D. , Welch C. , Miller R. , Uddi M. , Agrawal A. K. , Daniel Ron
Published: August 2018

Pressure gain combustion (PGC) has been conceived to convert fuel’s chemical energy into thermal energy and mechanical energy, thereby reducing the entropy production in the process. Recent research has shown that the rotating detonation combustion or combustor (RDC) can provide excellent specific thrust, specific impulse, and pressure gain within a small volume through rapid energy release by continuous detonation in the circumferential direction. The RDC as a PGC system for power generating gas turbines in combined cycle power plants could provide significant efficiency gains. However, few past studies have employed fuels that are relevant to power generation turbines, since RDC research has focused mainly on propulsion applications. In this study, we present experimental results from RDC operated on methane and oxygen-enriched air to represent reactants used in land-based power generation. The RDC is operated at a high pressure by placing a back-pressure plate downstream of the annular combustor.

Past studies have focused mainly on probe measurements inside the combustor, and thus, little information is known about the nature of the products exiting the RDC. In particular, it is unknown if chemical reactions persist outside the RDC annulus, especially if methane is used as the fuel. In this study, we apply two time-resolved optical techniques to simultaneously image the RDC products at framing rate of 30 kHz: (1) direct visual imaging to identify the overall size and extent of the plume, and (2) OH* chemiluminescence imaging to detect the reaction zones if any. Results show dynamic features of the combustion products that are consistent with the probe measurements inside the RDE. Moreover, presence of OH* in the products suggests that the oblique shock wave and reactions persist downstream of the detonation zone in the RDC.
Effects of Effusion Cooling Pattern Near the Dilution Hole for a Double-Walled Combustor Liner: Part 1 — Overall Effectiveness Measurements
Authors: Shrager Adam C. , Thole Karen A. , Mongillo Dominic
Published: August 2018

The complex flowfield in a gas turbine combustor makes cooling the liner walls a challenge. In particular, this paper is primarily focused on the region surrounding the dilution holes, which is especially challenging to cool due to the interaction between the effusion cooling jets and high-momentum dilution jets. This study presents overall effectiveness measurements for three different cooling hole patterns of a double-walled combustor liner. Only effusion hole patterns near the dilution holes were varied, which included: no effusion cooling; effusion holes pointed radially outward from the dilution hole; and effusion holes pointed radially inward toward the dilution hole. The double-walled liner contained both impingement and effusion plates as well as a row of dilution jets. Infrared thermography was used to measure the surface temperature of the combustor liners at multiple dilution jet momentum flux ratios and approaching freestream turbulence intensities of 0.5% and 13%.

Results showed the outward and inward geometries were able to more effectively cool the region surrounding the dilution hole compared to the closed case. A significant amount of the cooling enhancement in the outward and inward cases came from in-hole convection. Downstream of the dilution hole, the interactions between the inward effusion holes and the dilution jet led to lower levels of effectiveness compared to the other two geometries. High freestream turbulence caused a small decrease in overall effectiveness over the entire liner and was most impactful in the first three rows of effusion holes.
Increase of Glucose Uptake in Human Bone Marrow With Increasing Exercise Intensity
Authors: Heinonen Ilkka , Kemppainen Jukka , Fujimoto Toshihiko , Knuuti Juhani , Kalliokoski Kari K.
Published: August 2018

Human bone marrow is a metabolically active tissue that responds to acute low-intensity exercise by having increased glucose uptake (GU). Here, the authors studied whether bone marrow GU increases more with increased exercise intensities. Femoral bone marrow GU was measured using positron emission tomography and [18F]-fluorodeoxyglucose in six healthy young men during cycling at intensities of 30% (low), 55% (moderate), and 75% (high) of maximal oxygen consumption on three separate days. Bone marrow GU at low was 17.2 µmol·kg−1·min−1 (range 9.0–25.4) and increased significantly (p = .003) at moderate (31.2 µmol·kg−1·min−1, 22.9–39.4) but was not significant from moderate to high (37.4 µmol·kg−1·min−1, 29.0–45.7, p = .26). Furthermore, the ratio between bone and muscle GU decreased from low to moderate exercise intensity (p < .01) but not (p = .99) from moderate to high exercise intensity. In conclusion, these results show that although the increase is not as large as observed in exercising skeletal muscle, GU in femoral bone marrow increases with increasing exercise intensity at least from low- to moderate-intensity effort, which may be important for bone and whole-body metabolic health.
Situated Game Teaching Through Set Plays: A Curricular Model to Teaching Sports in Physical Education
Authors: Li Weidong , Xie Xiuye , Li Huanyu
Published: August 2018

Guided by Situated Learning theory, the purpose of this article is to propose an extension to existing game-centered curricular models, named Situated Game Teaching through Set Plays (SGTSP). This proposed model fills in the gaps in the literature on game-centered curricular models by theorizing the concept of game scenarios/match conditions in the coaching literature for physical education, utilizing Situated Learning theory as a theoretical framework to systematically develop a curricular model, and conceptualizing and operationalizing the stimulus-response selection and execution or if–then links decision-making process in teaching sports and games in physical education. This SGTSP model has a potential to advance the curricular development and provide an alternative approach to teach tactical decision making in sports and games in physical education. Future research shall examine the effectiveness of SGTSP curricular model on students’ motivation, tactical decision making, technique development, and game performance. Features of this model and implications for future research will be discussed.
Examining the Reciprocal Nature of Service-Learning for Underserved Students and Preservice Teachers
Authors: Galvan Christine , Meaney Karen , Gray Virginia
Published: August 2018

Background: Although service-learning scholarship in physical education teacher education (PETE) programs has shown positive results, little is known about the reciprocal benefits of PETE service-learning programs on underserved students and physical education preservice teachers.Purpose: This study examined the impacts on students and teachers of integrating two physical education curricula within a service-learning program using a mixed-methods approach.Methods: A pretest–posttest design investigated changes in cardiorespiratory endurance training among students (n = 50). Reflective journals, interviews, and field notes assessed program impact on preservice teachers (n = 16).Results: Findings revealed a significant improvement in cardiorespiratory endurance among students, while qualitative data provide evidence of increases in general pedagogical content, knowledge of curriculum, and knowledge of educational contexts among teachers.Discussion/Conclusion: This study adds important reciprocity findings to PETE service-learning literature.
Can a transgenic chestnut restore a forest icon?
Authors: Popkin Gabriel
Published: August 2018

Researchers seek permit to release American chestnut engineered to resist a deadly blight.
Hybridization may give some parasites a leg up
Authors: Pennisi Elizabeth
Published: August 2018

Genomic study helps explain how schistosomiasis gained a foothold in Europe.
The Use of Baker’s Yeast in the Resazurin Reduction Test: A Simple, Low-Cost Method for Determining Cell Viability in Proliferation and Cytotoxicity Assays
Authors: Bitacura Jayzon G.
Published: August 2018

Cell viability assays require expensive commercial testing kits and sophisticated cell culture techniques. Thus, a laboratory activity for testing the cellular proliferative and cytotoxic effects of certain substances using baker’s yeast (Saccharomyces cerevisiae) in resazurin reduction test (RRT) was developed. This activity is based on the fact that a laboratory-prepared resazurin has identical effects to a resazurin-based commercial kits and that S. cerevisiae is an established model system for eukaryotic organisms. Here, a complete procedure based on optimized conditions was described in detail, from preparation of test materials and solutions up to the gathering and analysis of data. This laboratory activity provides a simple and cheap alternative to conventional cell viability assays and is therefore recommended for use in institutions with limited budget for the acquisition of materials for instruction purposes.
Global prevalence and incidence of surgical site infections after appendectomy: a systematic review and meta-analysis protocol
Authors: Danwang Celestin , Mazou Temgoua Ngou , Tochie Joel Noutakdie , Nzalie Rolf Nyah Tuku , Bigna Jean Joel
Published: August 2018

Introduction

Acute appendicitis is a surgical emergency and the most frequent aetiology of acute surgical abdominal pain in developed countries. Universally, its widely approved treatment is appendectomy. Like all surgical procedures, appendectomy can be associated with many complications among which are surgical site infections (SSIs).

Despite the increasing number of appendectomies done around the world and the associated morbidities related to SSI after appendectomy, there is still scarcity of data concerning the global epidemiology of SSI after appendectomy. The current review aims at providing a summary of the published data on epidemiology of SSI after appendectomy.

Methods and design

We will include randomised controlled trials, cohort studies, case–control and cross-sectional studies. Electronic databases including Embase, MEDLINE and ISI Web of Science (Science Citation Index) will be searched for relevant abstracts of studies published between 1 January 2000 and 30 December 2017, without language restriction. The review will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. After screening of abstracts, study selection, data extraction and assessment of risk of bias, we shall assess the studies individually for clinical and statistical heterogeneity. Appropriate meta-analytic techniques will then be used to pool studies judged to be clinically homogenous. Visual inspection of funnel plots and Egger’s test will be used to detect publication bias. Results will be presented by country and continent.

Ethics and dissemination

Since primary data are not collected in this study, ethical approval is not required. This review is expected to provide relevant data to help in quantifying the global burden of SSI after appendectomy. The final report will be published in a peer-reviewed journal.

Trial registration number

CRD42017075257.
Factors influencing the decision to convey or not to convey elderly people to the emergency department after emergency ambulance attendance: a systematic mixed studies review
Authors: Oosterwold Johan , Sagel Dennis , Berben Sivera , Roodbol Petrie , Broekhuis Manda
Published: August 2018

Background

The decision over whether to convey after emergency ambulance attendance plays a vital role in preventing avoidable admissions to a hospital’s emergency department (ED). This is especially important with the elderly, for whom the likelihood and frequency of adverse events are greatest.

Objective

To provide a structured overview of factors influencing the conveyance decision of elderly people to the ED after emergency ambulance attendance, and the outcomes of these decisions.

Data sources

A mixed studies review of empirical studies was performed based on systematic searches, without date restrictions, in PubMed, CINAHL and Embase (April 2018). Twenty-nine studies were included.

Study eligibility criteria

Only studies with evidence gathered after an emergency medical service (EMS) response in a prehospital setting that focused on factors that influence the decision whether to convey an elderly patient were included.

Setting

Prehospital, EMS setting; participants to include EMS staff and/or elderly patients after emergency ambulance attendance.

Study appraisal and synthesis methods

The Mixed Methods Appraisal Tool was used in appraising the included articles. Data were assessed using a ‘best fit’ framework synthesis approach.

Results

ED referral by EMS staff is determined by many factors, and not only the acuteness of the medical emergency. Factors that increase the likelihood of non-conveyance are: non-conveyance guidelines, use of feedback loop, the experience, confidence, educational background and composition (male–female) of the EMS staff attending and consulting a physician, EMS colleague or other healthcare provider. Factors that boost the likelihood of conveyance are: being held liable, a lack of organisational support, of confidence and/or of baseline health information, and situational circumstances. Findings are presented in an overarching framework that includes the impact of these factors on the decision’s outcomes.

Conclusion

Many non-medical factors influence the ED conveyance decision after emergency ambulance attendance, and this makes it a complex issue to manage.
Association between type 1 diabetes mellitus and educational attainment in childhood: a systematic review protocol
Authors: Oakley Natalie Jayne , Kneale Dylan , Mann Mala , Hilliar Mariann , Tan Jeanette , Dayan Colin , Gregory John W , French Robert
Published: August 2018

Introduction

Type 1 diabetes has the potential to significantly impact children’s educational attainment. With the increase in incidence, quantifying this effect would be useful to assess how much additional support should be focused on children with type 1 diabetes in school.

Methods and analysis

We will conduct a systematic review of all observational studies and randomised controlled trials, including individuals both with and without a diagnosis of type 1 diabetes who have undertaken high stakes testing at the end of compulsory schooling when under 18 years of age. The search will cover both peer-reviewed and grey literature available from January 2004 to January 2018. The following seven databases will be searched: Ovid MEDLINE (1946 to present), Ovid MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid EMBASE (1947 to present), Thomson Reuters Web of Science, EBSCO Education Resources Information Center, EBSCO British Education Index and EBSCO Cumulative Index to Nursing and Allied Health Literature. Study selection and data extraction will be performed independently by two reviewers with any disagreements resolved via a third reviewer. The quality and risk of bias in the observational studies included in this review will be assessed using the Newcastle-Ottawa Scale. We aim to conduct a meta-analysis and will assess heterogeneity between the included studies and potential for publication bias if sufficient (>10) studies are included.

Results and dissemination

Formal ethical approval is not required as individual patient data will not be collected. Results will be disseminated through peer-reviewed publication and conference presentations.

PROSPERO registration number

CRD42017084078.
Prevalence and clinicopathological characteristics of mismatch repair-deficient colorectal carcinoma in early onset cases as compared with late-onset cases: a retrospective cross-sectional study in Northeastern Iran
Authors: Goshayeshi Ladan , Ghaffarzadegan Kamran , Khooei Alireza , Esmaeilzadeh Abbas , Rahmani Khorram Mahla , Mosannen Mozaffari Hooman , Kiani Behzad , Hoseini Benyamin
Published: August 2018

Objectives

Lynch syndrome (LS), a genetically inherited autosomal disorder, increases the incidence of colorectal carcinoma (CRC). We aimed to perform a universal strategy to assess the prevalence and clinicopathological characteristics of early onset CRCs at high risk of LS versus late-onset ones in the Iranian population.

Setting

A local population-based study from Northeastern Iran.

Participants

321 consecutive CRCs and pathology specimen screened between 2013 and 2016.

Primary and secondary outcome measures

Retrospectively, information regarding the clinical criteria was obtained by interviewing the patients with CRC or, their families. Pathologists tested tumours with immunohistochemistry (IHC) staining of four mismatch repair (MMR) proteins (MLH1, MSH2, MSH6andPMS2). Tumours with absent IHC staining ofMLH1were tested for BRAF mutations to exclude sporadic CRCs. Prevalence of early onset CRCs at high risk of LS and familial CRC type X were assessed as primary and secondary outcome measures, respectively.

Results

Of 321 CRCs (13/123 (10.57%), early onset vs 21/198 (10.6%) late-onset) were detected to be MMR-deficient (dMMR). Nine early onset cases and 14 late-onset ones with a loss ofMLH1underwent testing for the BRAF mutation, none of the early onset and four (2.02%) late-onset were recognised as sporadic. The difference in the outcome of IHC-analysis between early and late-onset CRCs at high risk of LS was not statistically significant (p=0.34). Majority of the suspected LS tumours from early onset patients had arisen in distal part (8/11 (72.72%) vs 8/14 (57.14%)), all of which were occurred in the rectum or sigmoid.

Conclusion

Clinically, these findings suggest that in case of limitation for BRAF testing, the practitioner in Iran may consider managing early onset dMMR cases like LS until access to BRAF testing becomes available to them, before germline testing to accurately diagnose LS.
A GEOMETRICAL APERTURE–WIDTH RELATIONSHIP FOR ROCK FRACTURES
Authors: GHANBARIAN BEHZAD , PERFECT EDMUND , LIU HUI-HAI
Published: August 2018

The relationship between fracture aperture (maximum opening; [Formula: see text]) and fracture width ([Formula: see text]) has been the subject of debate over the past several decades. An empirical power law has been commonly applied to relate these two parameters. Its exponent ([Formula: see text]) is generally determined by fitting the power-law function to experimental observations measured at various scales. Invoking concepts from fractal geometry we theoretically show, as a first-order approximation, that the fracture aperture should be a linear function of its width, meaning that [Formula: see text]. This finding is in agreement with the result of linear elastic fracture mechanics (LEFM) theory. We compare the model predictions with experimental observations available in the literature. This comparison generally supports a linear relationship between fracture aperture and fracture width, although there exists considerable scatter in the data. We also discuss the limitations of the proposed model, and its potential application to the prediction of flow and transport in fractures. Based on more than 170 experimental observations from the literature, we show that such a linear relationship, in combination with the cubic law, is able to scale flow rate with fracture aperture over [Formula: see text]14 orders of magnitude for variations in flow rate and [Formula: see text]5 orders of magnitude for variations in fracture width.
Ladder operators and a differential equation for varying generalized Freud-type orthogonal polynomials
Authors: Filipuk Galina , Mañas-Mañas Juan F. , Moreno-Balcázar Juan J.
Published: August 2018

In this paper, we introduce varying generalized Freud-type polynomials which are orthogonal with respect to a varying discrete Freud-type inner product. Our main goal is to give ladder operators for this family of polynomials as well as find a second-order differential–difference equation that these polynomials satisfy. To reach this objective, it is necessary to consider the standard Freud orthogonal polynomials and, in the meanwhile, we find new difference relations for the coefficients in the first-order differential equations that this standard family satisfies.