bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of NGV Lean Under Influence of Inlet Temperature Traverse
Authors: Rahim A. , Khanal B. , He L. , Romero E.
Published: November 2013

One of the most widely studied parameters in turbine blade shaping is blade lean, i.e. the tangential displacement of spanwise sections. However, there is a lack of published research that investigates the effect of blade lean under non-uniform temperature conditions (commonly referred to as a ‘hot-streak’) that are present at the combustor exit. Of particular interest is the impact of such an inflow temperature profile on heat transfer when the NGV blades are shaped.

In the present work a computational study has been carried out for a transonic turbine stage using an efficient unsteady Navier-Stokes solver (HYDRA). The configurations with a nominal vane and a compound leaned vane under uniform and hot-streak inlet conditions are analysed. After confirming the typical NGV loading and aero-loss redistributions as seen in previous literature on blade lean, the focus has been directed to the rotor aerothermal behavior. Whilst the overall stage efficiencies for the configurations are largely comparable, the results show strikingly different rotor heat transfer characteristics. For a uniform inlet, a leaned NGV has a detrimental effect on the rotor heat transfer. However, once the hot-streak is introduced, the trend is reversed; the leaned NGV leads to favourable heat transfer characteristics in general and for the rotor tip region in particular. The possible causal links for the observed aerothermal features are discussed.

The present findings also highlight the significance of evaluating NGV shaping designs under properly conditioned inflow profiles, rather than extrapolating the wisdom derived from uniform inlet cases. The results also underline the importance of including rotor heat transfer and coolability during the NGV design process.
Electrically Driven On Demand Oil System for Gas Turbine Engines
Authors: Spytek Christopher J.
Published: November 2013

An on demand oil system, based on electrically driven lube and scavenge pumps, for use in gas turbine engines has been developed. The need to optimize gas turbine engine performance, coupled with ‘electrification’ of aircraft systems, as on the Lockheed F35 and Boeing 787 in order to maximize efficiency and flexibility, created an opportunity to develop a ‘smart’ electrically driven lubrication system for gas turbine engines. Spytek’s electric oil system, developed for use on its 400lbt ATG-2 engine platform, ascertains the operating condition of the gas turbine engine, including speed, pressure, bearing temperatures and determines the amount of lubrication required for each bearing zone. The system has the benefit of better thermal control of engine bearings, lower system weight and power use, with flexibility in the placement of the system on the engine/airframe combination. The system has been successfully demonstrated on the Spytek Aerospace ATG-2/J304 gas turbine engine series.

Major areas addressed in the development of the system were the selection of reliable, gas turbine engine compatible feed and scavenge pumps, control systems sensoring and feedback, variable feed of oil to the individual sump wells, as well as systems durability and operating parameters. Various gas turbine engine platforms can require altered oil system duty cycles, including pre-oiling or post run down-oiling, high flow oil conditions, features not readily available in traditional mechanical systems but easily implemented using the Spytek on-demand oil system.

In the project effort, evaluation of the existing prototype system was used as a system design baseline. Data on pump wear, filter performance and oil supply degradation was available and used in refining the oil system design. The ATG-2 system was modified to take advantage of a full proportional integral derivative controlled oil system with system demonstrations made on a gas turbine engine, demonstrating oil supply on demand capability and full bearing thermal management system control.
Preliminary Aero Engine Life Assessment via Techno-Economic Environmental Risk Analysis
Authors: Navaratne Rukshan , Camilleri William , Najafi Esmail , Sethi Vishal , Pilidis Pericles
Published: November 2013

Significant progress has been made towards the improvement of engine efficiency through the increase in overall pressure ratio (OPR) and reduction in specific thrust (SFN). The implications of engine design extend beyond thermodynamics and should include the consideration of multi-disciplinary aspects related to operation, emissions, lifing and cost. This paper explores the relationship between fuel burn and engine life across the design space of a typical aircraft engine integrated system.

In this context the Cranfield University Techno-economic Environmental Risk Analysis (TERA) methodology allows for the assessment of environmental and economic risk when the design of an engine system is at its conceptual stage. It is essentially a multi-disciplinary optimization framework which can be used for design space exploration. Such an approach is necessary in order to assess the trade-off between asset life and powerplant efficiency at the preliminary stage of the design process.

A parametric study was conducted in order to assess the sensitivity of major design parameters on engine life and specific fuel consumption (SFC) for a given engine type. The principal failure modes of creep, fatigue and oxidation, were considered for engine life estimation. In addition an optimization study was carried out in order to investigate the trade-off between fuel burn and engine life as Time Between Overhaul (TBO). This was accomplished by integrating aircraft performance, engine performance and lifing models in the TERA Framework.

An increase in turbine entry temperature (TET) is required to maintain efficiency at OPR. However, as TET has a strong influence on engine life there is an important trade-off to be made against engine efficiency. The parametric study outlined in this work explores the design space both with respect to engine life as well as efficiency. The optimization study showed that a penalty of 1.42kg additional fuel is required per additional hour of TBO. The fuel penalty is a consequence of sub-optimal design parameters with respect to engine efficiency and is applicable for the presented engine aircraft combination.
Development and Validation of a Physics-Based, Dynamic Model of a Gas Turbine
Authors: Wiese Ashley P. , Blom Matthew J. , Brear Michael J. , Manzie Chris , Kitchener Anthony
Published: November 2013

This paper presents and validates a physics-based, dynamic model of a gas turbine. The model is an extension of that proposed by Badmus et al. [1], such that representation of a complete gas turbine is achieved. It includes new models of several gas turbine components, in particular the turbine and compressor, and also applies a well known method for prescribing boundary conditions [10] to the gas path.

This model first uses data from a previously published, static model of the same gas turbine to determine this dynamic model’s many so-called ‘forcing terms’. A least-squares optimisation is then undertaken to estimate the shaft inertia and the thermal inertia of system components using transient test data. Importantly, these optimised results are all close to physically reasonable estimates. Further, they show that the shaft dynamics are only significant for a short period at the start of most transients, after which the dynamic effects of thermal storage are dominant.

The complete gas turbine model is then validated against transient test data. Whilst the simulated traces demonstrate some steady-state error arising from the static model [12], the overall system dynamics appear to be captured well. Since steady-state error can be integrated out in a control system, this suggests that the proposed dynamic model is appropriate for use in a model-based, gas turbine controller.
A Critical Numerical Review of Loss Correlation Models and Smith Diagram for Modern Low Pressure Turbine Stages
Authors: Bertini Francesco , Ampellio Enrico , Marconcini Michele , Giovannini Matteo
Published: November 2013

The Smith diagram, originally published in 1965, has been largely exploited as a preliminary design (PD) tool for axial turbines. Currently, it is applied to aeronautical Low Pressure Turbines (LPTs) in order to define basic characteristics during the feasibility study and to compare different configurations.

The Smith diagram represents a correlation of stage performance (η) as function of flow coefficient (ϕ) and loading factor (Ψ), but it does not take into account the effects of some important input parameters (individual contributions of loss, Reynolds number, Aspect Ratio, Rotor Tip Clearance (RTC)) and does not report some key design outputs (deflection angles (δ), profile weights and stresses), which have also a direct relation with the configuration position on the Smith diagram.

This study employs meanline analyses incorporating traditional loss correlation models used in the turbine field to compare results with the original Smith diagram. The correlation approach allows one to obtain other important multidisciplinary information (primarily aero-mechanical) which was previously absent, which leads to some strategic design achievements. The investigation process is based on a reference two-stage turbine properly set to match specific operating points on the Smith diagram. Several three-dimensional blade geometries have been prepared and then detailed 3D CFD analyses have been performed in order to acquire confidence with respect to the meanline results.

This research adds important information for turbine module design to the Smith chart and allows for a numerical revision of the diagram itself, fine tuning it with data obtained from the analyses of modern blades optimized for high stage performance.

Finally numerically-based loss predictors, broadly applicable to LPTs during optimization procedures before detailed CFD analyses, are presented and discussed.
Implementation of Speed Variation in the Structural Dynamic Assessment of Turbomachinery Flow Path Components
Authors: Brown Andrew M. , Davis R. Benjamin , DeHaye Michael K.
Published: November 2013

During the design of turbomachinery flow path components, the assessment of possible structural resonant conditions is critical. Higher frequency modes of these structures are frequently found to be subject to resonance, and in these cases, design criteria require a forced response analysis of the structure with the assumption that the excitation speed exactly equals the resonant frequency. The design becomes problematic if the response analysis shows a violation of the HCF criteria. One possible solution is to perform “finite-life” analysis, where Miner’s rule is used to calculate the actual life in seconds in comparison to the required life. In this situation, it is beneficial to incorporate the fact that, for a variety of turbomachinery control reasons, the speed of the rotor does not actually dwell at a single value but instead dithers about a nominal mean speed and during the time that the excitation frequency is not equal to the resonant frequency, the damage accumulated by the structure is diminished significantly. Building on previous investigations into this process, we show that a steady-state assumption of the response is extremely accurate for this typical case, resulting in the ability to quickly account for speed variation in the finite-life analysis of a component which has previously had its peak dynamic stress at resonance calculated. A technique using Monte Carlo simulation is also presented which can be used when specific speed time histories are not available. The implementation of these techniques can prove critical for successful turbopump design, as the improvement in life when speed variation is considered is shown to be greater than a factor of two.
Experimental and CFD Study of a Rectangular S-Bend Passage With and Without Pressure Recovery Effects
Authors: Ng Billy C. N. , Birk A. M.
Published: November 2013

Flow fields in a rectangular S-bend passage were simulated to benchmark the capability of RANS based CFD in modeling such complex flow passages with/without the effects of flow diffusion over a range of Reynolds numbers from 250,000 to 430,000. Numerical results were validated against the experimental data of pressure coefficient, wall static pressure distributions, and outflow velocity contours. Parametric studies were conducted to examine the effects of inlet turbulence properties in conjunction with the use of various turbulence models (k-ε, realizable k-ε and SST k-ω). Improvements in prediction accuracies using detailed computational domains were also examined including (i) lengthened inlet section to simulate upstream flow development, and (ii) addition of downstream flow domain to better simulate flow diffusion to an ambient outlet. Altering model geometry and inlet boundary conditions along with the use of different turbulence models had minimal improvements in the simulation results. The CFD results demonstrated that the S-bend flow features and the increasing trends of pressure magnitudes with higher Reynolds numbers were reasonably simulated. Limitations in predicting the diffusing flow fields were evident with the over predictions of pressure recovery. The study also showed the better reliabilities of the k-ε model for the simulations of S-bend flow fields through the comparisons of outflow velocity profiles.
Testing Platform and Commercialization Plan for Heat Exchanging Systems for SCO2 Power Cycles
Authors: Fleming Darryn , Pasch Jim , Conboy Thomas , Carlson Matt
Published: November 2013

Supercritical Closed Brayton Cycle (SCO2 CBC) systems have the potential to convert thermal energy to electricity at an efficiency significantly higher than traditional steam Rankine cycles. The primary difference in the Brayton cycle that enables higher efficiency is the availability of a useful temperature difference between the high temperature, low pressure flow exiting the turbine, and the low temperature, high pressure flow exiting the compressor. In the SCO2 CBC cycle, this temperature difference drives heat transfer through recuperation in heat exchangers. Overall cycle energy conversion efficiency increases as the extent of recuperation increases. Ideally, the low pressure flow temperature exiting the last heat exchanger before entering the compressor will equal the high pressure flow temperature exiting the compressor. Both heat exchanger capital costs and power plant operating income rise as this ideal is approached. The capital costs are considered in relation to their effect on profit from a SCO2 CBC power plant selling electricity. Sandia is currently designing a heat exchanger test platform to support research and development of heat exchanger technology for SCO2 power cycles. This platform will facilitate investigating performance characteristics of various new heat exchanger technologies, such as pressure drop, efficiency, failure modes, etc. The platform will be able to accommodate many types of exchangers of different physical sizes and flow rates. The purpose of this testing is to identify the correct heat exchanger for the many various SCO2 applications. Testing will be a focal point of the research and commercialization plan for Sandia to identify a path forward to develop a 10MW simple recuperated Brayton cycle. The platform, once commissioned, can test many types of heat exchangers to investigate performance characteristics and to select which application they will be best suited for. Characterizing these heat exchangers will facilitate understanding how they scale. Plant economics will be a major factor in the selection of these heat exchangers. It has been identified that at this time, up to 90% of the cost of the SCO2 Brayton Cycle will be in the heat exchangers. This percentage assumes the use of printed circuit heat exchangers. Although these heat exchanger are approximately 98% efficient and a relatively high cost, the use of a lower efficiency and less costly heat exchanger may make this SCO2 technology more attractive for a path forward commercialization.
Rotordynamic Force Prediction of an Unshrouded Radial Inflow Turbine Using Computational Fluid Dynamics
Authors: Lerche Andrew H. , Musgrove Grant O. , Moore J. Jeffrey , Kulhanek Chris D. , Nordwall Grant
Published: November 2013

Cross-coupled forces due to bladed components, bearings and seals can contribute to destabilizing a rotor system and are an important input to the rotordynamic design of turbomachinery. Alford (1965) developed a simple formula for describing the cross-coupled mechanism of an unshrouded axial turbine stage. The high flow radial inflow turbine studied here can exhibit similar characteristics due to its long stage length. In this work, a transient computational solution is developed to predict cross-coupling stiffness of an unshrouded turbo-expander. The three-dimensional computational fluid dynamics (CFD) model includes the flow path from the inlet guide vanes (IGV’s) to the exit of the radial inflow turbine. A 360 degree model of the flow path is used to simulate the turbine centered at its axis of rotation while the shroud is displaced a small distance from the axis of rotation. This offset simulates the uneven blade tip clearance that is present in a whirling rotor. Unsteady effects are included using a time-transient simulation while time-averaged forces acting on the turbine are used to calculate the cross-coupling aerodynamic coefficients. The rotordynamic coefficients calculated using this method are compared to both the Alford equation and formulations used for shrouded centrifugal compressor impellers.
Effect of Manufacturing Variability on Turbine Engine Performance: A Probabilistic Study
Authors: Gorelik Michael , Obayomi Jacob , Slovisky Jack , Frias Dan , Swanson Howie , McFarland John , Enright Michael , Riha David
Published: November 2013

While turbine engine Original Equipment Manufacturers (OEMs) accumulated significant experience in the application of probabilistic methods (PM) and uncertainty quantification (UQ) methods to specific technical disciplines and engine components, experience with system-level PM applications has been limited.

To demonstrate the feasibility and benefits of an integrated PM-based system, a numerical case study has been developed around the Honeywell turbine engine application. The case study uses experimental observations of engine performance such as horsepower and fuel flow from a population of engines. Due to manufacturing variability, there are unit-to-unit and supplier-to-supplier variations in compressor blade geometry. Blade inspection data are available for the characterization of these geometric variations, and CFD analysis can be linked to the engine performance model, so that the effect of blade geometry variation on system-level performance characteristics can be quantified. Other elements of the case study included the use of engine performance and blade geometry data to perform Bayesian updating of the model inputs, such as efficiency adders and turbine tip clearances.

A probabilistic engine performance model was developed, system-level sensitivity analysis performed, and the predicted distribution of engine performance metrics was calibrated against the observed distributions. This paper describes the model development approach and key simulation results. The benefits of using PM and UQ methods in the system-level framework are discussed.

This case study was developed under Defense Advanced Research Projects Agency (DARPA) funding which is gratefully acknowledged.
Radial Turbine Rotor Response to Pulsating Inlet Flows
Authors: Cao Teng , Xu Liping , Yang Mingyang , Martinez-Botas Ricardo F.
Published: November 2013

The performances of automotive turbocharger turbines have long been realized to be quite different under pulsating flow conditions compared to that under the equivalent steady and quasi-steady conditions on which the conventional design concept is based. However, the mechanisms of this phenomenon are still intensively investigated nowadays.

This paper presents an investigation of the response of a stand-alone rotor to inlet pulsating flow conditions by using validated unsteady Reynolds Averaged Navier-Stokes solver (URANS). The effects of the frequency, the amplitude and the temporal gradient of pulse waves on the instantaneous and cycle integrated performances of a radial turbine rotor in isolation were studied, decoupled from the upstream turbine volute. Numerical method was used to help gaining the physical understandings of these effects.

A validation of the numerical method against the experiments on a full configuration of the turbine has been performed prior to the numerical tool being used in the investigation. The rotor is then taken out to be studied in isolation. The results show that the turbine rotor alone can be treated as a quasi-steady device only in terms of cycle integrated performance; however, instantaneously, the rotor behaves unsteadily which increasingly deviates from the quasi-steady performance as the local Strouhal number of the pulsating wave is increased. This deviation is dominated by the effect of quasi-steady time-lag; at higher local Strouhal number, the transient effects also become significant. Based on this study, an interpretation and a model of estimating the quasi-steady time lag have been proposed; a criterion for unsteadiness based on the temporal local Strouhal number concept is developed, which reduces to the Λ criterion proposed in the published literature when cycle averaged; this in turn emphasizes the importance of the pressure wave gradient in time.
Simulation of Transitional Flow on Low Pressure Turbine Blade With Unsteady Downstream Potential Interaction
Authors: Ma Can , Yuan Xin
Published: November 2013

This paper numerically investigates the transitional flow on a LPT (low pressure turbine) blade with fluctuating downstream potential field. A linear T106 cascade is subjected to an oscillating potential field generated by downstream moving bars. Previous experimental results in open literature showed that the unsteady downstream potential field has an obvious influence on the transitional boundary layer of LPT blade. For the numerical simulations in this paper, the unsteady Reynolds-Averaged Navier-Stokes equations are solved using the commercial software FLUENT. The transition model used in this paper is the γ-Reθ model, which has been validated against a number of transitional flows previously, including the influence of upstream wakes on the transitional boundary layer of T106 turbine blade. The simulation results are first compared to the experimental results in open literature to validate the numerical methods. Two different FSTI (free stream turbulence intensity), 1.6% and 4.0% are investigated with axial spacing between the blade and the downstream bar varying from 50% axial chord to 25% axial chord. To investigate the influence of flow compressibility, two different inlet Mach numbers, 0.02 and 0.2 are simulated. Results show that decreasing the axial spacing has an influence on the unsteady boundary layer separation and transition and the influence is enhanced at elevated inlet Mach number.
Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter
Authors: Xi Jiaqi , Zhang Qiang , Li Mian , Wang Zhaoguang
Published: November 2013

Supersonic wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiment, the stagnation pressure in the test section is required to remain constant. Due to the nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required, which is then capable of properly working under different operating conditions. In this paper, an Extended Kalman Filter (EKF) based flow control strategy is proposed and implemented in the controller. The control strategy is designed based on the state estimation of a real blowdown wind tunnel, which is carried out under an EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the controller parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.
An Analytical Model for Boundary Layer Control via Steady Blowing and its Application to NACA-65-410 Cascade
Authors: Sarimurat Mehmet N. , Dang Thong Q.
Published: November 2013

In this paper, boundary-layer flow-control technique via steady blowing for low-speed compressor cascade applications is investigated using an analytical model based on the integral method and Computational Fluid Dynamics (CFD). The integral method is developed and used to investigate the effect of the momentum, the velocity magnitude and the angle of the blowing flow on the behavior of the boundary layer. It is found that the change in the boundary layer momentum thickness across the blowing location is a linear function of the blown-flow momentum coefficient and a decaying function of the blown-flow velocity ratio. For the case when the size of the blowing slot and the velocity magnitude of the blown flow are kept constant, and the blowing mass flow rate is increased by increasing the blowing angle, there is an “optimum” blowing angle that maximizes the benefit of the boundary layer blowing. This angle increases with increasing velocity ratio and reaches an asymptotic value of 45°. According to the model, the change in the momentum thickness across the blowing location is conveyed exponentially downstream, thus a small change in the momentum thickness due to flow blowing can have significant effect downstream. The developed model is applied to the NACA-65-410 low speed cascade using CFD, and good agreement between theory and CFD is obtained.
Analytical and Experimental Study of Dynamic Characteristics of Rod Fastened Rotor-Bearing System Under Preload Saturation
Authors: Lu Mingjian , Geng Haipeng , Xu Guohui , Yu Lie , Wang Weimin
Published: November 2013

This paper investigates the dynamic characteristics of a composite rotor fastened by rods. Contact stiffness and equivalent bending stiffness between discs with different rod preloads of the rotor are obtained respectively by using the elastic and elastic-plastic contact theory. The finite element model of rotor-bearing system is built with Timoshenko beam elements. Critical speeds are respectively calculated with and without the consideration of contact effect, including the changing bearing dynamic coefficients. A test rig of rod fastening rotor-bearing system has been constructed to verify the numerical model results. The results show that the critical speed increases with rod preload and it keeps almost constant when the rod preload reaches a certain value, called preload saturation. The experiments demonstrate that the rod fastening rotor under preload saturation has the similar dynamic characteristics as integral rotor, such as the critical speed and backward whirl with asymmetric support stiffnesses. This kind of rotors which are under preload saturation can be analyzed and designed as an integral one without considering the contact effect. The study gives referential recommendations for analysis and design of a class of composite rotors which contain discs and rods.
Axial Compressor Degradation Effects on Heavy Duty Gas Turbines Overall Performances
Authors: Astrua Pio , Cecchi Stefano , Piola Stefano , Silingardi Andrea , Bonzani Federico
Published: November 2013

The operation of a gas turbine is the result of the aero-thermodynamic matching of several components which necessarily experience aging and degradation over time. An approach to treat degradation phenomena of the axial compressor is provided, with an insight into the impact they have on compressor operation and on overall GT performances. The analysis is focused on the surface fouling of compressor blades and on rotor tip clearances variation.

A modular model is used to simulate the gas turbine operation in design and off-design conditions and the aerodynamic impact of fouling and rotor tip clearances increase is assessed by means of dedicated loss and deviation correlations implemented in the 1D mid-streamline code of the compressor modules.

The two different degradation sources are individually considered and besides the overall GT performance parameters, the analysis includes an evaluation of the compressor degradation impact on the secondary air system.
An Efficient 3D CFD Model for the Analysis of the Flow Field Around Darrieus Rotors
Authors: Torresi Marco , Fortunato Bernardo , Camporeale Sergio Mario
Published: November 2013

An efficient numerical technique has been developed in order to investigate flow characteristics and global performance of Darrieus rotors. The interest for this kind of vertical axis wind turbines arises from their great capacity for integration within urban areas and for distributed generation.

The proposed methodology is based on the solution of the steady three-dimensional governing equations, by means of a robust commercial CFD code. Since the effect of the turbine blades on the flow field is simulated through the introduction of momentum sources in the porous shell representing the volume swept by the turbine blades, any expensive refinement of the grid, near the rotor, is avoided. This approach dramatically reduces the computational costs, with respect to conventional unsteady flow simulations. The model efficiency enables the simulation of the flow field around Darrieus rotors considering complex and realistic computational domains, for instance when these turbines are clustered within a wind farm or placed inside urban areas.

The methodology is validated by reproducing the performance of the Sandia 17-meter Darrieus rotor with approximate troposkien shape. Comparisons with other codes are also presented in order to highlight the advantages of the proposed method.
Stationary Component Optimization and the Resultant Improvement in the Performance Characteristics of a Radial Compressor Stage
Authors: Fakhri Syed , Sorokes James M. , Vezier Clementine , Pacheco Jorge E.
Published: November 2013

This paper is a follow-up to work published by Sorokes et al. [16] regarding a diffuser flow-field phenomenon, identified as a precursor to stall in a centrifugal stage. The earlier work provided greater detail on the phenomenon that occurred, including further details on the CFD analyses done to investigate the phenomenon and the trends observed in the test data. The numerical and experimental results described in the earlier work were used as a foundation in developing improved stationary components of another stage of similar design whose surge margin fell short of expectation, with the goal of improving its surge margin and overall performance. The study focused specifically on improving the flow characteristics in the diffuser and return channel by optimizing the geometry. The improvement in surge margin and overall performance was first verified numerically (through CFD analysis) and then experimentally via scale model testing.

The paper will provide an overview of the centrifugal stage that was tested along with a description of the test vehicle, operating conditions and instrumentation used. The paper will also include a description of the numerical work completed; i.e., the CFD code used, computational domain considered and boundary conditions applied. Comparisons of the trends observed in the experimental and numerical work will be offered and the agreement between the numerical and empirical results will be assessed. Finally, performance comparisons of the optimized stage with the previous stage will also be presented.
SUMO-1
Gene Transfer Improves Cardiac Function in a Large-Animal Model of Heart Failure
Authors: Tilemann Lisa , Lee Ahyoung , Ishikawa Kiyotake , Aguero Jaume , Rapti Kleopatra , Santos-Gallego Carlos , Kohlbrenner Erik , Fish Kenneth M. , Kho Changwon , Hajjar Roger J.
Published: November 2013

Cardiac gene delivery of small ubiquitin-related modifier 1 (
SUMO-1
) improved cardiac function and stabilized left ventricular volumes in a swine model of ischemic heart failure.
Sclerostin Inhibition Reverses Skeletal Fragility in an Lrp5-Deficient Mouse Model of OPPG Syndrome
Authors: Kedlaya Rajendra , Veera Shreya , Horan Daniel J. , Moss Rachel E. , Ayturk Ugur M. , Jacobsen Christina M. , Bowen Margot E. , Paszty Chris , Warman Matthew L. , Robling Alexander G.
Published: November 2013

Humans with osteoporosis pseudoglioma syndrome might benefit from sclerostin neutralization therapies.
A complex odontoma of the anterior maxilla associated with an erupting canine
Authors: Pillai Ajay , Moghe Swapnil , Gupta Mithilesh K , Pathak Abhishek
Published: November 2013

Many developmental anomalies of the jaw are accidentally diagnosed during radiographic investigations for other symptoms. Complex odontomas are odontogenic tumours, relatively rare in the anterior maxilla and generally asymptomatic. Frequently the odontoma may interfere with the eruption of teeth. This paper describes a case of complex odontoma in an 8-year-old girl, which resulted in the palatal displacement of the lateral incisor and an erupting permanent canine. A calcified mass was seen on the radiograph and was provisionally diagnosed as an odontoma which was surgically enucleated. Routine follow-up was carried out for more than 1 year and no recurrence was seen.
Mortality following a brain tumour diagnosis in patients with multiple sclerosis
Authors: Montgomery Scott , Hassan Ahmad , Bahmanyar Shahram , Brus Ole , Hussein Oula , Hiyoshi Ayako , Hillert Jan , Olsson Tomas , Fall Katja
Published: November 2013

Objectives

As brain tumours and their treatment may theoretically have a poorer prognosis in inflammatory central nervous system diseases such as multiple sclerosis (MS), all-cause mortality following a brain tumour diagnosis was compared between patients with and without MS. The potential role of age at tumour diagnosis was also examined.

Setting

Hospital inpatients in Sweden with assessment of mortality in hospital or following discharge.

Participants

Swedish national registers identified 20 543 patients with an MS diagnosis (1969–2005) and they were matched individually to produce a comparison cohort of 204 163 members of the general population without MS. Everyone with a primary brain tumour diagnosis was selected for this study: 111 with MS and 907 without MS.

Primary and secondary outcome measures

5-year mortality risk following brain tumour diagnosis and age at brain tumour diagnosis.

Results

A non-statistically significant lower mortality risk among patients with MS (lower for those with tumours of high-grade and uncertain-grade malignancy and no notable difference for low-grade tumours) produced an unadjusted HR (and 95% CI) of 0.75 (0.56 to 1.02). After adjustment for age at diagnosis, grade of malignancy, sex, region of residence and socioeconomic index, the HR is 0.91 (0.67–1.24). The change in estimate was largely due to adjustment for age at brain tumour diagnosis, as patients with MS were on average 4.7 years younger at brain tumour diagnosis than those in the comparison cohort (p<0.001).

Conclusions

Younger age at tumour diagnosis may contribute to mortality reduction in those with high-grade and uncertain-grade brain tumours. Survival following a brain tumour is not worse in patients with MS; even after age at brain tumour diagnosis and grade of malignancy are taken into account.
Prevalence of Bronchiectasis in Asthma according to Oral Steroid Requirement: Influence of Immunoglobulin Levels
Authors: Luján Manel , Gallardo Xavier , Amengual María José , Bosque Montserrat , Mirapeix Rosa M. , Domingo Christian
Published: November 2013

Purpose. To establish the prevalence of bronchiectasis in asthma in relation to patients’ oral corticosteroid requirements and to explore whether the increased risk is due to blood immunoglobulin (Ig) concentration.Methods. Case-control cross-sectional study, including 100 sex- and age-matched patients, 50 with non-steroid-dependent asthma (NSDA) and 50 with steroid-dependent asthma (SDA). Study protocol: (a) measurement of Ig and gG subclass concentration; (b) forced spirometry; and (c) high-resolution thoracic computed tomography. When bronchiectasis was detected, a specific etiological protocol was applied to establish its etiology.Results. The overall prevalence of bronchiectasis was 12/50 in the SDA group and 6/50 in the NSDA group (p=ns). The etiology was documented in six patients (four NSDA and two SDA). After excluding these patients, the prevalence of bronchiectasis was 20% (10/50) in the SDA group and 2/50 (4%) in the NSDA group (P<0.05). Patients with asthma-associated bronchiectasis presented lower FEV1values than patients without bronchiectasis, but the levels of Ig and subclasses of IgG did not present differences.Conclusions. Steroid-dependent asthma seems to be associated with a greater risk of developing bronchiectasis than non-steroid-dependent asthma. This is probably due to the disease itself rather than to other influencing factors such as immunoglobulin levels.
Combined Heat and Power Dynamic Economic Dispatch with Emission Limitations Using Hybrid DE-SQP Method
Authors: Elaiw A. M. , Xia X. , Shehata A. M.
Published: November 2013

Combined heat and power dynamic economic emission dispatch (CHPDEED) problem is a complicated nonlinear constrained multiobjective optimization problem with nonconvex characteristics. CHPDEED determines the optimal heat and power schedule of committed generating units by minimizing both fuel cost and emission simultaneously under ramp rate constraints and other constraints. This paper proposes hybrid differential evolution (DE) and sequential quadratic programming (SQP) to solve the CHPDEED problem with nonsmooth and nonconvex cost function due to valve point effects. DE is used as a global optimizer, and SQP is used as a fine tuning to determine the optimal solution at the final. The proposed hybrid DE-SQP method has been tested and compared to demonstrate its effectiveness.
Association of Human Leukocyte Antigen Class I Polymorphism with Spontaneous Clearance of Hepatitis B Surface Antigen in Qidong Han Population
Authors: Miao Fengqin , Sun Hang , Pan Ning , Xu Jinhuan , Qiu Jie , Shen Yuqing , Xie Wei , Zhang Jianqiong
Published: November 2013

Aim. To investigate whether HLA class I polymorphisms could influence the clearance of hepatitis B surface antigen (HBsAg) in Qidong Han population.Methods. We genotyped HLA-A, -B, and -C loci of 448 individuals with HBV persistent infection and 140 persons with spontaneous clearance of HBsAg by polymerase chain reaction with sequencing based typing (PCR/SBT). All the individuals were unrelated males enrolled from Qidong Han population and were followed up for 10 years.Results. The frequency ofHLA-A*33:03:01Gwas increased in persistent HBV infection group (Pvalue is 0.028), while frequency ofHLA-B*13:01:01Gwas increased in HBsAg clearance group (Pvalue is 0.0004).Conclusion. These findings suggested that the host HLA class I polymorphism is an important factor in determining the outcomes of HBV infection.
Review of the Wall Temperature Prediction Capability of Available Correlations for Heat Transfer at Supercritical Conditions of Water
Authors: Ramasamy Dhanuskodi , Appusamy Arunagiri , Narayanan Anantharaman
Published: November 2013

The validity of the wall temperature predictions by 18 correlations available in the literature for supercritical heat-transfer regimes of water was verified for 12 experimental datasets consisting of 355 data points available in the literature. The correlations were ranked based on criteria like % data with <5% error, % data with <10°C error and minimum error band in temperature prediction. Details of the best fitting correlations were tabulated. The analysis indicated that for normal heat-transfer conditions, most of the correlations give close predictions. However, at deteriorated heat transfer regimes, only very few prediction points are closer to experimental value. Also, in the ranking process, the first position keeps varying, and no one correlation shall be said as the best for all experiments. Evaluation of the applicability of heat flux to mass-flux-ratio-based prediction of heat-transfer deterioration indicated 75% agreement. The empirical formulae linking mass flux for the prediction of the starting heat flux for heat-transfer deterioration indicated 58.33% of agreement. This review indicated that continued precise experimentation covering wide range of parameter conditions near pseudocritical regime and development of correlations is felt necessary for the accurate prediction of supercritical fluid heat transfer.
Allicin Attenuates Inflammation and Suppresses HLA-B27 Protein Expression in Ankylosing Spondylitis Mice
Authors: Gu Xin , Wu Haishan , Fu Peiliang
Published: November 2013

Here we aimed to determine the therapeutic effect of allicin on ankylosing spondylitis (AS) and explore the mechanism(s) of action. AS mouse model was constructed by transferring the HLA-B2704 gene into Kunming mice and verified by RT-PCR and CT imaging. Verified AS mice were randomly divided into model group (n=6) and allicin-treated groups (50, 100, and 200 mg/kg, resp.,n=6, p.o., for 2 months). Wild type mice were used as control (n=6). The levels of AS-related inflammatory factors were measured by ELISA. mRNA and protein expressions of HLA-B27 were checked by RT-PCR and western blotting. As the results, the mouse model of AS was successfully established, and high-dose allicin could markedly alleviate spine inflammatory injury possibly via reducing the secretion of the inflammatory factors (IL-6, IL-8, and TNF-α) sharply in AS mice. Moreover, allicin significantly inhibited HLA-B27 protein translation but failed to suppress HLA-B27 gene transcription in AS mice, indicating a posttranscriptional mechanism of this modulation. In conclusion, allicin has potential to be used for AS treatment as an anti-inflammatory nutraceutical.
Fixed Point Theorems of Quasicontractions on Cone Metric Spaces with Banach Algebras
Authors: Liu Hao , Xu Shaoyuan
Published: November 2013

We introduce the concept of quasicontractions on cone metric spaces with Banach algebras, and by a new method of proof, we will prove the existence and uniqueness of fixed points of such mappings. The main result generalizes the well-known theorem of Ćirić (Ćirić 1974).
Intravital Microscopic Research of Microembolization with Degradable Starch Microspheres
Authors: Ebert Micaela , Ebert Juergen , Berger Gerd
Published: November 2013

Treatment efficacy in cancer patients using systemically applied cytostatic drugs is decreased by cytotoxic side effects, which limits the use of efficient dosages. Degradable starch microspheres (DSM) are used to apply drugs into blood vessels which supply the target organ leading to drug accumulation in the target organ by reduction of the blood flow. The present investigations show that DSM is a very effective embolization material leading to effective and enhanced accumulation of 5-FU within the liver tumor tissue of experimental induced liver cancer in rats. By using intravital microscopy, a rapid deceleration of the blood flow into the target organ is observed immediately after application of DSM. The microspheres are stepwise degraded in the direction of the systemic blood flow and are totally dissolved after 25 minutes. These stepwise processes leave the degraded material during the degradation process within the vessels leading to temporally reciprocal blood flow via some of the side-arms of the major blood vessels. By using DMS in transarterial chemoembolization (TACE), severe adverse side effects like postembolization syndrome are rarely observed when compared to other embolization materials. The complete degradation of DSM causes only a short-lasting temporary vascular occlusion, which allows a repeat application of DSM in TACE.
Horizontal Vibration of a Large-Diameter Pipe Pile in Viscoelastic Soil
Authors: Zheng Changjie , Liu Hanlong , Ding Xuanming , Fu Qiang
Published: November 2013

An analytical solution is developed in this paper to investigate the horizontal dynamic response of a large-diameter pipe pile in viscoelastic soil layer. Potential functions are applied to decouple the governing equations of the outer and inner soil. The analytical solutions of the outer and inner soil are obtained by the method of separation of variables. The horizontal dynamic response and complex dynamic stiffnesses of the pipe pile are then obtained based on the continuity conditions between the pile and the outer and inner soil. To verify the validity of the solution, the derived solution in this study is compared with an existing solution for a solid pile. Numerical examples are presented to analyze the vibration characteristics of the pile and illustrate the effects of major parameters on the stiffness and damping properties.
A Strategy Based on Cooperative Transmission for Minimizing Delivery Delay in WSN
Authors: Yang Qingyu , Yang Xinyu , Wang Yu , An Dou
Published: November 2013

To achieve the purpose of energy conservation, various sleep scheduling approaches, such as duty cycle, are applied in wireless sensor networks (WSN). However, the duty-cycle mechanism results in data delivery latency, which is critical to monitor applications. To minimize the delay caused by sleeping nodes in the transmission path, we propose to “hop over” the sleeping nodes based on the range extension of cooperative transmission (CT). The transmission delay models for the random duty-cycled WSN and optimized fixed duty-cycled WSN under cooperative operation are formulated, and an algorithm named (delay-tolerant cooperative transmission DTCT) is presented for the selection of transmission modes to avoid waiting for the sleeping nodes to wake up. The energy consumption model under direct transmission (DT) and CT mode is also presented. Theoretical analysis shows that sleep latency can be greatly reduced in the cooperative scheme, and it is validated by simulations that it outperforms the traditional store-and-forward (DT) mode in delivery latency. Especially, CT reduces 67% and 14.3% of the transmission delay in random and optimized fixed low duty-cycled WSN, respectively, and DTCT algorithm saves energy by 11.29% in random low duty-cycled WSN.
Hydrodynamic Characterization of thePolyodon spathulaRostrum Using CFD
Authors: Allen Jeffrey B. , Riveros Guillermo
Published: November 2013

Among the various functions of the paddlefish rostrum, it is also believed to serve as a stabilizer to counteract the downward force that would otherwise occur during the process of filter feeding. From its unique shape, it is hypothesized that the paddlefish rostrum serves to generate a substantial amount of lift that naturally occurs as the rostrum is elevated at the same time the fish opens its mouth. The present, numerical study is an attempt to quantify the amount of lift (and drag) that is generated by the rostrum of a juvenile paddlefish. Additionally, this data is compared with other hydrofoils. The results suggest that the paddlefish rostrum does indeed produce substantial lift at certain angles of attack. In fact, the results indicate that the amount of lift is comparable to that produced by a symmetric foil (NACA 0012).