bluuebunny/crossref_metadata_2025 huggingface dataset:
Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF) directly from positive blood culture flasks allows rapid identification of bloodstream infections in immunosuppressed hosts
Authors: Egli A. , Osthoff M. , Goldenberger D. , Halter J. , Schaub S. , Steiger J. , Weisser M. , Frei R.
Published: February 2015

Introduction

In immunosuppressed hosts, rapid identification of microorganisms of bloodstream infections is crucial to ensuring effective antimicrobial therapy. Conventional culture requires up to 72 h from sample collection to pathogen identification.

Methods

We used the SepsiTyper Kit and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF; Microflex, Bruker) directly from positive blood culture (BacT/ALERT 3D, FN/FA vials; bioMérieux) in comparison to standard culture methodology (VITEK 2; bioMérieux) for species identification.

Results

A total of 62 consecutive positive blood cultures from immunosuppressed patients (solid organ or hematopoietic transplant recipients, or with febrile neutropenia) were analyzed. Culture yielded gram‐negative bacteria (GNB) in 27/62 (43.5%) and gram‐positive (GPB) in 35/62 (56.5%) vials. For GNB, the predominant species identified by MALDI‐TOF and confirmed by VITEK were Escherichia coli (16/16 correctly identified) and Enterobacter cloacae (4/4), with a sensitivity and specificity of 92.6% and 100%, respectively. For GPB, predominant species were Staphylococcus aureus (3/3), coagulase‐negative staphylococci (12/24), and Enterococcus faecium (6/6) with a sensitivity of 100%, 60%, and 100%, respectively. The median time from blood collection to species identification was 27.4 h with MALDI‐TOF identification and 46.6 h with conventional methodology.

Conclusion

Using MALDI‐TOF directly from positive blood cultures allowed a shorter time to identification with high sensitivity and specificity in immunosuppressed patients.
Molecular techniques to interrogate and edit the Chlamydomonas nuclear genome
Authors: Jinkerson Robert E. , Jonikas Martin C.
Published: February 2015

The success of the green alga Chlamydomonas reinhardtii as a model organism is to a large extent due to the wide range of molecular techniques that are available for its characterization. Here, we review some of the techniques currently used to modify and interrogate the C. reinhardtii nuclear genome and explore several technologies under development. Nuclear mutants can be generated with ultraviolet (UV) light and chemical mutagens, or by insertional mutagenesis. Nuclear transformation methods include biolistic delivery, agitation with glass beads, and electroporation. Transforming DNA integrates into the genome at random sites, and multiple strategies exist for mapping insertion sites. A limited number of studies have demonstrated targeted modification of the nuclear genome by approaches such as zinc‐finger nucleases and homologous recombination. RNA interference is widely used to knock down expression levels of nuclear genes. A wide assortment of transgenes has been successfully expressed in the Chlamydomonas nuclear genome, including transformation markers, fluorescent proteins, reporter genes, epitope tagged proteins, and even therapeutic proteins. Optimized expression constructs and strains help transgene expression. Emerging technologies such as the CRISPR/Cas9 system, high‐throughput mutant identification, and a whole‐genome knockout library are being developed for this organism. We discuss how these advances will propel future investigations.
SUSCEPTIBILITY ARTIFACTS ON T2*‐WEIGHTED MAGNETIC RESONANCE IMAGING OF THE CANINE AND FELINE SPINE
Authors: Hammond Laura J. , Hecht Silke
Published: February 2015

The T2*‐weighted gradient recalled echo sequence is a sensitive means to detect blood degradation products. While not a routine sequence in magnetic resonance imaging of the spine in small animals, it can provide additional valuable information in select cases. The goal of this retrospective, cross‐sectional study was to describe findings when acquiring this sequence during magnetic resonance imaging examination of the spine in small animals. The University of Tennessee's veterinary radiology database was searched for dogs and cats that underwent magnetic resonance imaging for suspect spinal disease in which a T2*‐weighted gradient recalled echo sequence was acquired and susceptibility artifact was identified. The following information was recorded: signalment, clinical signs, location and appearance of susceptibility artifact, and final diagnosis. Thirty‐nine cases were included in the study. Extradural susceptibility artifacts were observed in cases of intervertebral disc herniation with or without associated hemorrhage (n = 28), extradural hemorrhage associated with spinal trauma (n = 2), hemophilia (n = 1), and in a cystic extradural mass (n = 1). Remaining lesions displaying susceptibility artifact were intramedullary and included presumptive acute noncompressive nucleus pulposus extrusion (n = 2), hematoma (n = 1), hemangiosarcoma metastasis (n = 1), intramedullary disc extrusion (n = 1), presumptive meningomyelitis (n = 1), and a mass of undetermined etiology (n = 1). Inclusion of a T2*‐weighted gradient recalled echo sequence may be helpful in spinal magnetic resonance imaging when standard imaging sequences are ambiguous or intramedullary lesions are observed.
Yamuna Kachru and world Englishes
Authors: BOLTON KINGSLEY
Published: February 2015

Professor Yamuna Kachru brought an enormous energy and commitment to the world Englishes (WE) enterprise over three decades. Her research and publications were characterized by a unique intelligence, informed by her expert knowledge of South Asian linguistics, as well as a lively and curious intellect fascinated by many other aspects of language studies. Her contribution to world Englishes was lucidly informed by her own experiences of India and by her deep and comprehensive research on South Asian languages. The arc of her research career can be traced from South Asian linguistics through contrastive discourse analysis to a wide variety of research and publications on world Englishes, about which she co‐authored three volumes, and published more than forty research papers. Her work continues to serve as an inspiration for WE scholars and students throughout the world.
Mapping Yamunaji's scholarly tributaries: Childhood education and professional writing
Authors: PANDEY ANITA
Published: February 2015

This paper recognizes and celebrates Dr. Yamuna Kachru's multiple research contributions. Continuing with the metaphor of the powerful River Yamuna that the preceding paper uses, this one explores two tributaries or, more specifically, two applications of her research, namely, the value of her contributions to the field of childhood education and to professional communication. Implications and directions for future research are also outlined.
Professor Yamuna Kachru's scholarly work: A bibliography
Authors: BOLTON KINGSLEY , SMITH LARRY E. , SRIDHAR S. N.
Published: February 2015

This article comprises an extensive bibliography that maps the arc of Professor Yamuna Kachru's publications over a period of forty‐six years, from 1965–2011. This bibliography not only reflects the productivity of Professor Kachru's scholarly endeavors, but also provides a testament to the breadth and diversity of her academic and research interests, which is also the focus of the substantive articles contributed to this special issue. It is our intention that this bibliography should not only stand as a record of a remarkable and inspiring academic leader, but also as a point of reference for future generations of scholars, who, in their turn, will be inspired by her research.
With admiration, gratitude, and deep respect: In honor of Professor Yamuna Kachru (1933–2013)
Authors: BOLTON KINGSLEY , DAVIS DANIEL R.
Published: February 2015

Professor Yamuna Kachru spent her early years in India, where she completed her BA and MA studies in Hindi language and literature, as well as a Diploma in Linguistics. She went to the UK in 1959, where she taught at SOAS, and completed her PhD. In 1965 she moved to the University of Illinois at Urbana‐Champaign to join her husband Professor Braj B. Kachru in the Linguistics Department. Over the course of her career she published an impressive body of work that included research on South Asian linguistics, Hindi language studies, applied linguistics, Asian Englishes, contrastive rhetoric, discourse analysis, and cross‐cultural communication. Her many awards include the Presidential Award for her research and publications on Hindi linguistics, which she received from the President of India in 2006. The collection of papers in this special issue pays tribute to her life and work, with much admiration, gratitude and deep respect.
Poly‐N‐acetyl glucosamine nanofibers for negative‐pressure wound therapies
Authors: Fulco Ilario , Erba Paolo , Valeri Robert C. , Vournakis John , Schaefer Dirk J
Published: February 2015

The wound healing promoting effect of negative wound pressure therapies (NPWT) takes place at the wound interface. The use of bioactive substances at this site represents a major research area for the development of future NPWT therapies. To assess wound healing kinetics in pressure ulcers treated by NPWT with or without the use of a thin interface membrane consisting of poly‐N‐acetyl glucosamine nanofibers (sNAG) a prospective randomized clinical trial was performed. The safety of the combination of NPWT and sNAG was also assessed in patients treated with antiplatelet drugs. In the performed study, the combination of NPWT and sNAG in 10 patients compared to NPWT alone in 10 patients promoted wound healing due to an improved contraction of the wound margins (p = 0.05) without a change in wound epithelization. In 6 patients treated with antiplatelet drugs no increased wound bleeding was observed in patients treated by NPWT and sNAG. In conclusion, the application of thin membranes of sNAG nanofibers at the wound interface using NPWT was safe and augmented the action of NPWT leading to improved wound healing due to a stimulation of wound contraction.
Topical administration of a connexin43‐based peptide augments healing of chronic neuropathic diabetic foot ulcers: A multicenter, randomized trial
Authors: Grek Christina L. , Prasad G.M. , Viswanathan Vijay , Armstrong David G. , Gourdie Robert G. , Ghatnekar Gautam S.
Published: February 2015

Nonhealing neuropathic foot ulcers remain a significant problem in individuals with diabetes. The gap‐junctional protein connexin43 (Cx43) has roles in dermal wound healing and targeting Cx43 signalling accelerates wound reepithelialization. In a prospective, randomized, multicenter clinical trial we evaluated the efficacy and safety of a peptide mimetic of the C‐terminus of Cx43, alpha connexin carboxy‐terminal (ACT1), in accelerating the healing of chronic diabetic foot ulcers (DFUs) when incorporated into standard of care (SOC) protocols. Adults with DFUs of at least four weeks duration were randomized to receive SOC with or without topical application of ACT1. Primary outcome was mean percent ulcer reepithelialization and safety variables included incidence of treatment related adverse events (AEs) and detection of ACT1 immunogenicity. ACT1 treatment was associated with a significantly greater reduction in mean percent ulcer area from baseline to 12 weeks (72.1% vs. 57.1%; p = 0.03). Analysis of incidence and median time‐to‐complete‐ulcer closure revealed that ACT1 treatment was associated with a greater percentage of participants that reached 100% ulcer reepitheliazation and a reduced median time‐to‐complete‐ulcer closure. No AEs reported were treatment related, and ACT1 was not immunogenic. Treatment protocols that incorporate ACT1 may present a therapeutic strategy that safely augments the reepithelialization of chronic DFUs.
Newton's lemma XXVIII on integrable ovals in higher dimensions and reflection groups
Authors: Vassiliev V. A.
Published: February 2015

We prove that there are no bounded domains with smooth boundaries in even‐dimensional Euclidean spaces, such that the volumes cut off from them by affine hyperplanes depend algebraically on these hyperplanes. For convex ovals in , this is Lemma XXVIII from Newton's ‘Philosophiae naturalis principia mathematica’.
Multiscale Transient Thermal Analysis of Microelectronics
Authors: Barabadi Banafsheh , Kumar Satish , Sukharev Valeriy , Joshi Yogendra K.
Published: February 2015

In a microelectronic device, thermal transport needs to be simulated on scales ranging from tens of nanometers to hundreds of millimeters. High accuracy multiscale models are required to develop engineering tools for predicting temperature distributions with sufficient accuracy in such devices. A computationally efficient and accurate multiscale reduced order transient thermal modeling methodology was developed using a combination of two different approaches: “progressive zoom-in” method and “proper orthogonal decomposition (POD)” technique. The capability of this approach in handling several decades of length scales from “package” to “chip components” at a considerably lower computational cost, while maintaining satisfactory accuracy was demonstrated. A flip chip ball grid array (FCBGA) package was considered for demonstration. The transient temperature and heat fluxes calculated on the top and bottom walls of the embedded chip at the package level simulations are employed as dynamic boundary conditions for the chip level simulation. The chip is divided into ten function blocks. Randomly generated dynamic power sources are applied in each of these blocks. The temperature rise in the different layers of the chip calculated from the multiscale model is compared with a finite element (FE) model. The close agreement between two models confirms that the multiscale approach can predict temperature rise accurately for scenarios corresponding to different power sources in functional blocks, without performing detailed FE simulations, which significantly reduces computational effort.
Flow Simulation of Jet Deviation by Rotating Pelton Buckets Using Finite Volume Particle Method
Authors: Vessaz Christian , Jahanbakhsh Ebrahim , Avellan François
Published: February 2015

The objective of the present paper is to perform numerical simulations of a high-speed water jet impinging on rotating Pelton buckets using the finite volume particle method (FVPM), which combines attractive features of smoothed particle hydrodynamics (SPH) and conventional grid-based finite volume. The particles resolution is first validated by a convergence study. Then, the FVPM results are validated with available measurements and volume of fluid (VOF) simulations. It is shown that the pressure field in the buckets inner wall is in good agreement with the experimental and numerical data and the evolution of the flow pattern matches the high-speed visualization.
Plasma-Fuel Systems for Fuel Preparation, Ignition, Combustion and Gasification
Authors: Messerle V. E. , Ustimenko A. B. , Lavrichshev O. A.
Published: February 2015

A review of the developed plasmachemical technologies of pyrolysis, hydrogenation, thermochemical treatment for combustion, gasification, radiation-plasma, and complex conversion of solid fuels, including uranium-containing slate coal, and cracking of hydrocarbon gases, is presented. The use of these technologies for obtaining target products (hydrogen, carbon black, hydrocarbon gases, synthetic gas, and valuable components of the coal mineral mass) meet the modern experimental and economic requirements to the power sector, metallurgy and chemical industry. Plasma coal conversion technologies are characterized by a small time of reagents retention in the reactor and a high rate of the original substances conversion to the target products without catalysts. Thermochemical treatment of fuel for combustion is performed in a plasma fuel system, representing a reaction chamber with a plasmatron, while other plasma fuel conversion technologies are performed in a combined plasmachemical reactor of 100 kW nominal power, in which the area of heat release from the electric arc is combined with the area of chemical reactions.
Optimization of Compressor Blade Geometry for Efficiency and Pressure Ratio Under Strength Constraint
Authors: Shabliy L. S. , Cherniaev A. V.
Published: February 2015

The article describes an example of design optimizing of gas turbine compressor blade row with coupled simulation (coupled gas dynamics and strength) using technology of fluid-structure-interaction simulation by ANSYS tools. Geometry model, gas-dynamic model, finite element model and optimization technology used in work are described in detail. Optimized design parameters obtained showed improvements of 8% in efficiency and 7% in pressure ratio over the baseline compressor without decrease in safety factor.
Performance Enhancement of an Electric Submersible Pump
Authors: Adhav Rohit S. , Samad Abdus , Kenyery Frank
Published: February 2015

A numerical analysis and optimization has been done for a single stage electric submersible pump (ESP) which is basically a centrifugal pump to retrofit into wellbore in groundwater pumping or oil pumping. The pump is designed and simulated using a commercial code. The objective was to improve the pump performance if the inlet and outlet angles of impeller and diffuser are modified. Hence, the variables were the blade angles and 15 different designs were produced via Latin hyper cube sampling within the variable ranges. The designs were evaluated to find the hydraulic efficiency or the objective function value using a Reynolds average Navier Stokes equation solver. Two surrogates were constructed from the CFD results and the optimal points were predicted. The optimal designs were again evaluated using CFD solver and further analyses were made. It was found that the efficiency was increased by 4.23%.
Design Modification to Enhance Fatigue Life of an Aero-Engine Heat Shield
Authors: Singh Amar , Kalloor Joseph Shibu
Published: February 2015

An aero-engine heat shield made up of corrosion resistance steel sheet and mounted between the nozzle box and the exhaust unit of a gas turbine engine was frequently getting rejected due to crack initiation at the periphery of the apertures. Also higher amplitude of vibration was observed in heat shield during operation of the engine. A detailed structural and vibration analysis of the heat shield was carried out to find out the reasons for this pre-matured failure. Based on the results of the analysis, the heat shield was modified, by introducing flat stiffeners, welded around the apertures to evade crack initiation. This modification increased fatigue life and reduced vibration level of the heat shield. The heat shield is successfully subjected to airworthiness qualification test in the aero-engine test bed and subsequently type certified for use in engine.
Studies on Transitional Heat Transfer Characteristics Over Turbine Vane Surface Using a High Order LES Approach
Authors: Biswas Debasish
Published: February 2015

The boundary layer developing on a turbo-machinery blade usually starts as a laminar layer but in most situations it inevitably becomes turbulent. The transition from laminar to turbulent in the boundary layer, which often causes a significant change in operational performance of the machinery, is generally influenced by the free-stream turbulence level, the pressure gradient, and surface curvature, etc. Therefore, boundary layer transition is an important phenomenon experienced by the flow through gas turbine engines. A substantial fraction of the boundary layer on both sides of a gas turbine airfoil may be transitional. The extended transition zone exist due to strong favorable pressure gradients, found on both near the leading edge portion of the suction side and the pressure side, which serve to stabilize the boundary layer and consequently delay the transition process, even under high free-stream turbulence intensity (FSTI) in practical gas turbine. It is very important to properly model and predict the high FSTI transition mechanism, since boundary layer transition leads to substantial increase in friction coefficients and heat transfer rate. Boundary layer separation, which is expected to be a significant problem on the suction side of some high pressure turbine airfoils due to shock-boundary layer interaction, also depends strongly on the state of boundary layer with respect to transition. Acceleration rates, Reynolds numbers and FSTI play very important role in controlling the boundary layer transition on the pressure side of gas turbine airfoils. The main objective of the present work is to study the performance of a high order LES turbulence model in predicting the transitional heat transfer characteristics over turbine vane surface under high pressure turbine flow conditions. In this regard the model is assessed to the precise experimental data where measurements were carried out in moderate temperature using three-vane cascades under steady state conditions. Two types of vane configurations were used in the experiment. The aerodynamic configurations of the two vanes were carefully selected to emphasize fundamental differences in the character of suction surface pressure distributions and the consequent effect on surface heat transfer distributions. In both the experiments and the computations, principle independent parameters (Mach number, Reynolds number, turbulence intensity, and wall-to-gas temperature ratio) were varied over ranges consistent with actual engine operation. The computed results explained measured data very satisfactorily and helped to have a very good understanding of basic mechanism involved in the complex flow behavior and transition from laminar to turbulent flow.
Aerodynamic Performance Evaluation of a Novel Savonius-Style Wind Turbine Under an Oriented Jet
Authors: Roy Sukanta , Mukherjee Prasenjit , Saha Ujjwal K.
Published: February 2015

The Savonius-style wind turbine, a class of vertical axis wind turbines, can be a viable option for small scale off-grid electricity generation in the context of renewable energy applications. A better self-starting capability at low wind speeds is one of the major advantages of this turbine. However, as reported in open literature, the power coefficient of the conventional design is found to be inferior as compared to its counterparts. In this regard, a new blade design has been developed. In the present investigation, the aerodynamic performance of this newly designed turbine is assessed under an oriented jet. This is affected by installing deflectors upstream of the turbine blades. The intention of this study is to maximize the utilization of wind energy at the exhaust systems of several practical applications. Experiments are carried out in a low speed wind tunnel at a wind speed of 6.2 m/s. The gradual loads applied to the turbine, and the corresponding rotational speeds are recorded. Power and torque coefficients are calculated at various mechanical loads. Further, all the estimated data are corrected by a suitable correction factor to account for the wind tunnel blockage effects. The results obtained are compared with the experimental data of modified Bach and conventional designs. The results have shown a significant improvement in the performance of newly designed Savonius-style wind turbine under the concentrated and oriented jet.
Gas Turbine Compartment Ventilation System
Authors: Kothakapu Divya , Avishetti Srinivas
Published: February 2015

The configuration of the compartment ventilation system is an important requirement in the gas turbine industry. The purpose of heating and ventilation system is to keep the turbine compartment within a fixed temperature envelope for at least personnel safety, equipment protection and reduction of turbine distortion by maintaining circumferentially uniform temperature distribution. The ventilation system also provides capability to detect and dilute the leaks by continually purging potential gas build up areas. Displacement ventilation is commonly used for the above considerations.

The current GE approach is to perform CFD analysis to quantify the ventilation fan flow rate and arrive at fan static pressure head through simplified 1-D calculations.

A detailed CFD geometric model is developed by including the entire turbine, piping, major support structure, all components with stringent temperature limits, ventilation inlets and outlets, enclosure roof and walls to verify the flow field. The fan static pressure head for various ambient conditions is obtained through 1-D calculations using the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) duct-fitting database.

The goal of this work is: (1) accurate modeling of the components within the enclosure for better prediction of component temperatures; (2) consideration of solar radiation; and (3) integration of the 1-Dimensional Flowmaster models and 3-Dimensional CFD results to improve the predictions from One-Dimensional model.
Novel Approach Towards Thrust Bearing Pad Cooling
Authors: Najar F. A. , Harmain G. A.
Published: February 2015

The present paper analyzes the thermal effect on a sector shaped pad extensively used in thrust bearings which supports the heavy axial loads. Large hydro-generator thrust bearings are susceptible to too much thermo-elastic deformation when oil film thickness is subjected to high pressure and temperature which can even lead to the bearing failure. So as a remedy, this study is an effort towards reducing the oil film temperature by incorporating a suitable cooling treatment. The cooling circuit, in this study, essentially follows a path of hot spots observed by solving Reynolds equation, energy equation and generalized Fourier heat conduction equation. The numerical scheme followed during investigation is finite difference method (FDM). The water circuit developed is just beneath the Babbitt lining of the pads. It has been observed that overall temperature has reduced significantly as compared to traditional cooling systems.
Reduction in Secondary Losses in Turbine Cascade Using Contoured Boundary Layer Fence
Authors: Deshpande Srikanth , Thern Marcus , Genrup Magnus
Published: February 2015

Present work deals with reducing secondary losses in turbine cascade by using boundary layer fences in two ways. Firstly, to reduce the strength of vortex which is incident at the leading edge of airfoil and hence reduce the strength of horse shoe vortex, and secondly, to reduce the pressure gradient between the pressure side and the suction side in the flow passage region between airfoils. In previous works, the boundary layer fence followed the profile of airfoil. In this publication, boundary layer fence does not follow the profile of airfoil i.e stagger and camber of boundary fence is different when compared to airfoil.

A profiled boundary layer fence is proposed in the present work which reduces the incident vorticity and also reduces pressure gradient from pressure side to suction side. Such boundary layer fence was checked on T106 test cascade which is available as open literature. Numerical work is carried out using commercial software Ansys CFX. Viscous RANS simulations are carried out using k-ω SST turbulence model with yplus value around unity on all walls. Coefficient of secondary kinetic energy (CSKE) and Secondary Kinetic energy helicity (SKEH) are used as target functions. Total pressure loss is also monitored. All the three functions show a reduction in secondary loss. The strength of horse shoe vortex is reduced by the fence protruding in front of leading edge. The converging flow passage created by the fence near the pressure side of airfoil reduces the pressure gradient from pressure side to suction side. The total pressure loss was reduced by 1.5 % and CSKE was improved by 36 % when the boundary layer fence was adopted.
Design and Analysis of Crown Profile of Fan Rotor Blade Roots for Gas Turbines
Authors: Dave Gaurav R. , Krishnaswamy Ramachandra , Chandrappa Lohith M. , Kulkarni Krishna , Jain Nikhil
Published: February 2015

The present work is aimed at reducing the stresses developed at the fillet region of the fan disk through crowning of the dovetail flanks of blade roots. The crowning was done along the flank (in-plane crowning) and across the flank (out-of-plane crowning) of the blade root and their influence on the fillet and flank stresses was studied independently, for varying crown heights. A generalized blade root and disk model was analyzed by the finite element method using ANSYS WorkBench 14.5 as a tool, by varying the crown height in different combinations. It was found that out-of-plane crowning of the blade flank is more effective in reducing the stresses at the fillet than in-plane crowning. The final optimization study will include the influence of 3-D crowning, combining the cumulative influence of in-plane and out-of-plane crowning, as well as the realistic gas bending and vibratory forces on actual 3-D airfoils.
An Internal Heat Transfer Study in a Cooled Nozzle Guide Vane of a Linear Cascade
Authors: Pujari Arun Kumar , Subrahmanyaa Prasad B. V. S. S. , Nekkanti Sitaram
Published: February 2015

Experimental and computational heat transfer investigations are reported in the interior mid span of the pressure surface of a Nozzle Guide Vane (NGV) subjected to combined impingement and film cooling. The study is carried out by considering a two dimensional cascade domain having four passages formed between the five vane each has a chord length of 228 mm and spacing (between the blades) of 200 mm. The vane internal surface is cooled by two impingement inserts namely front and aft impingement tubes. The front impingement tube is used to cool the internal side of the leading edge of the NGV whereas the aft impingement tube is used to cool mainly the mid span of the internal surface. The mass flow through the impingement chamber is varied for a fixed target plate distance to jet diameter ratio of 1.12. The surface temperature at the mid chord region was measured by liquid crystal technique. The surface temperature obtained from both experiments and computations are compared and the computationally obtained average heat transfer coefficient distribution along chord reported. The flow structure variation along the chord and its effect on Nusselt number distribution is presented. The computation is carried out by using Shear stress transport (SST) k-ω turbulence model in the ANSY FLUENT-14 flow solver.
A Theoretical and Computational Analysis of the Bolted Joint: A Sensitivity Study of Temperature Effect on the Turbocharger Inlet Bolted Joint in Locomotive Engines
Authors: Khudhir Ali K. A. , Aggarwal Mahesh C. , Sirak Michael , Panza Michael J.
Published: February 2015

The bolted joint is a very popular method of fastening together different components and one of the most important factors of machine design. Any mechanical failure of the bolted joint in rail industries can affect their financial, safety, and public confidence. In this paper, the primary objective was to create a bolted joint model to analyze the behavior of the turbocharger inlet bolted joint on a GE Transportation engine under room and working temperature. Theoretical and computational analyses investigations have been undertaken to determine the behavior of a turbocharger inlet bolted joint at room and working temperature based on VDI 2230 Part 1 and SR1+ program. Also, the reliability and validity of turbocharger inlet bolts were evaluated depending on their safety factors. A computational analysis has been performed for both structural and thermo structural loads that applied to the turbocharger inlet bolted joint.

The results obtained show that the stresses on the bolted joint increased 25% at working temperature. Also, the strength of the bolted joint has a direct relationship with amount of tightening torque applied to the bolt while the position of the bolts has a major effect on the behavior of the bolted joint. In addition, the analysis showed that the turbocharger inlet bolted joint behaved differently depending on the loads type. The study also confirmed that the preliminary design had reduced margin at working temperature, and additional design modifications were required. It was determined that the loosening of the bolted joint and insufficient preload were the main reasons of failure.
Heat Transfer and Flow Studies of Different Cooling Configurations for Gas Turbine Rotor Blade
Authors: Suresh Batchu , Brijesh Ainapur , Kesavan V. , Kumar S. Kishore
Published: February 2015

Military gas turbine engine operates at turbine entry temperatures (TET) of the order of 2000K. Increase in TET improves thermal efficiency and power output. The gas temperature is far above the allowable metal temperature of turbine components. Hence, there is a need to cool the components such as blades and vanes for safe operation. The blades are cooled by combination of internal convective cooling and external film-cooling. Rib tabulators are widely used in blade cooling passages to enhance heat transfer. In the present study, different rib tabulator configurations have been studied. 1D flow network model of blade cooling passages have been modeled using Flowmaster software. Flowmaster software estimates pressure losses, rotational effects and heat transfer of the coolant flow in the blade passages. Cooling passages are modeled as ducts while film cooling holes, impingement holes, tip holes and ejection holes are modeled as orifices. Experimentally measured heat transfer and pressure loss correlations are used in the analysis. The coolant pressure at inlet and sink pressure at exit of film cooling holes are given as input. The heat load coming on to the blade is also given as input for predicting the coolant temperature rise and blade metal temperature. The thermal analysis is carried out with different shaped rib turbulators such as V and W ribs with broken and continuous pattern. It is observed that thermal performance factor for a broken V rib configuration is better than other configurations. The metal temperature for broken V ribbed configuration is 25°C less compared other configurations. The effect of rotation on the blade temperature is also studied. The convective bulk temperatures and convective heat transfer coefficients obtained from 1D flow network are applied on 2D Finite Element (FE) model to obtain nodal temperature distribution.
Reynolds Number Effects on the Calibration of a Subminiature Four Hole Three Dimensional Wake Probe
Authors: Tatpatti Gajanan , Nekkanti Sitaram
Published: February 2015

A subminiature four-hole probe is designed and fabricated to be used specifically to measure wakes that occur in turbomachinery and its components. The probe has a nominal measuring area of 0.413 mm2 and has a nominal dimension of 0.254 mm in the direction across the wake downstream the trailing edge of a blade thus minimizing spatial and flow gradient errors in this direction. The non-nulling calibration of the probe is carried out in the pitch and yaw angle range of ±30° at 5° interval. The probe is calibrated at four different velocities, viz., 10 m/s, 20 m/s, 30 m/s and 50 m/s corresponding to the probe thickness Reynolds numbers in the range of 159 to 794 with objective of finding the effect of Reynolds number on the calibration coefficients. In addition to these, for practical importance the actual changes in yaw angle, pitch angle, static pressure, total pressure and velocity magnitude due to Reynolds number variation has been investigated. A method to incorporate the effect of Reynolds number for minimum interpolation errors is described.
Numerical Investigation of Soot Formation in Turbulent Diffusion Flames Using Moss-Brookes Model
Authors: Reddy Mannedhar , De Ashoke
Published: February 2015

In the present work, two different turbulent diffusion flames are investigated for soot predictions using the presumed shape multi-environment Eulerian PDF (EPDF) as turbulence-chemistry closure. In this approach, the chemical equation is represented by multiple reactive scalars and finite number of Delta functions are used to describe the shape of joint composition PDF, while the truncated series expansion in spherical harmonics (P1 approximation) is used to solve the radiative heat-transfer equation. The absorption coefficient is modeled using the weighted sum of gray gases model (WSGG) considering four fictitious gases. The soot volume fraction is predicted using acetylene based soot inception model (Moss-Brookes model). The model accounts for inception, surface growth and oxidation processes of soot. An equilibrium based approach is used to determine the OH radical concentration, required for soot oxidation. A single variable PDF in terms of temperature is used to include the turbulence-chemistry effects on soot. An effective absorption coefficient is calculated to include the influence of radiative heat transfer on soot. The combined tool is used to determine the soot formation in two hydrocarbon flames (Delft flame III, pilot stabilized natural gas flame and an unconfined C2H4/air jet flame). The soot formation rate decreases with the inclusion of radiation for both the flames and indicate the need for delineation of radiative heat transfer. The effects of soot-turbulence interaction are consistent with available literature. The effect of collision efficiency on oxidation rate can be clearly explicated from the predictions of C2H4/air flame.
Effect of Manufacturing Tolerances on the Turbine Blades
Authors: Kolmakova Daria , Baturin Oleg , Popov Grigorii
Published: February 2015

The quantification of geometric and physical variables uncertainty impact on turbomachinery row workflow was conducted using several untwisted airfoil cascades of axial turbine nozzle blades with uniform section throughout the channel height.

Profile loss coefficient, mass flow parameter, outlet flow angle were accepted as controlled performance criteria.

The series of computational calculations were carried out for these cascades. The first group of calculations was aimed at the identification of the impact of geometric parameters uncertainty on nozzle blades parameters. The second group - at identifying the studied parameters depending on the flow parameters changes that are used as boundary conditions in the simulation.

The obtained results showed that initial data uncertainty in CFD calculations has a significant impact on the obtained quantitative estimates. The difference between calculated data modified in accordance with the geometry technological tolerances and workflow parameters measurement error may exceed 5% by value of the considered criteria.
Bolted Joint Simulation Techniques in Gas Turbine Components
Authors: Jalammanavar Kuberappa , Kasina Lakshman , Srinivasan Raghavan Kotur , Shivaramaiah Prasanna , Kuncham Ramakrishnayya Gupta
Published: February 2015

Bolted joints are integral part of many industrial applications such as the most simple to the most complex and expensive machinery. They provide the primary means of connecting components. These joints play an important role in the integrity and durability of the systems. Bolted joint simulation is one of the important aspects of designing and evaluating any assembly. FE modeling simulation for bolted joint pose limitations in terms of simulating the real life bolted joint behavior. Simulation should be accurate enough but also simple enough to solve model faster.

There are many practices exist that helps the analyst to simulate the bolted joint. These practices need to be reviewed in detail and evaluated against high fidelity 3D finite element model. The physical behavior of the bolted joint can be simulated accurately by 3D bolted joint with preload, friction and contact between mating parts. The detail 3D modeling of bolted joint for the complex assembly models with multiple bolted joints will be very expensive in terms of computational cost and time. This study presents multiple methods of bolted joints simulation using ANSYS® 12.1[1]. The bolted joint model simulated using beam element is very effective in terms of computational cost, time and memory usage for complex assembly models. Bolted joint simulation with threads happens to be the most rigorous with the results and this method is a yardstick. Other approaches are evaluated from points of view of accuracy and effort effectiveness. This paper also presents the bolted joint analysis best practices on using above methods for various stages of component design. Typical gas turbine flange is taken for case study.
Large Amplitude Free Vibration Analysis of Axially Functionally Graded Plates
Authors: Kumar Saurabh , Roy Haraprasad , Mitra Anirban
Published: February 2015

Large amplitude free vibration problem of axially functionally graded plates under the action of uniformly distributed load is analyzed using energy method. A variational approach has been applied for the generation of governing differential equations. A two part solution procedure has been adopted, where the static solution is sought in the first part and the dynamic problem is taken up subsequently as a standard Eigen-value problem. The governing differential equations for the static analysis are derived from the principle of minimum total potential energy whereas Hamilton’s principle is used for developing the governing equations for the dynamic analysis. Start functions for the analysis are chosen by satisfying the flexural and membrane boundary conditions and Gram-Schmidt orthogonalization procedure is used for developing the higher order functions. The dynamic behavior is presented as backbone curves in non-dimensional frequency amplitude plane. Mode shape plots for linear and non-linear frequencies are given to show the effect of vibration amplitude on dynamic behavior. The results are compared with the works of other researchers which confirms the accuracy of the present research work.
Application of Genetic Algorithm for Fault Detection in Cracked Composite Structure
Authors: Dash A. K. , Agarwalla D. K. , Das H. C. , Pradhan M. K. , Bhuyan S. K.
Published: February 2015

Machines and beam like structures used in various industries require continuous monitoring for the fault identification for ensuring uninterrupted service. Different non-destructive techniques (NDT) are generally used for this purpose, but they are costly and time consuming. Vibration based methods can be useful to detect cracks in structures using various artificial intelligence (AI) techniques. The modal parameters from the dynamic response of the structure are used for the purpose. In the current analysis, the vibration characteristics of a glass fiber reinforced composite cracked cantilever beam having different crack locations and depths have been studied. Numerical and finite element methods have been used to extract the diagnostic indices (natural frequencies, mode shapes) from cracked and intact beam structure. An intelligent Genetic Algorithm (GA) based controller has been designed to automate the fault identification and location process. Single point crossover and in some cases mutation procedure have been followed to find out the optimal solution from the search space. The controller has been trained in offline mode using the simulation and experimental results (initial data pool) under various healthy and faulty conditions of the structure. The outcome from the developed controller shows that the system could not only detect the cracks but also predict their locations and severities. Good agreement between the simulation, experimental and GA controller results confirms the effectiveness of the proposed controller.
A Balanced IIRS Model for Investigating the Dynamics of Damped Rotor Bearing System
Authors: Chandraker S. , Roy H.
Published: February 2015

In this paper the application of the balanced Iterative Improved Reduction model techniques to complex rotor-bearing systems is investigated. It is demonstrated that, Iterative Improved Reduction System (IIRS) improves the matrix reductions by ensuring that the transformation matrix for each reduction is optimized. This reduction technique also benefices the problem due to skew symmetric matrices, which arises for inclusion of gyroscopic effect and internal damping. Numerical examples are solved to demonstrate the validity and efficiency of the reduced order model in representing the dynamics of the actual rotor system. Under these conditions, the complex behaviour of the rotor-shaft is studied to get an insight of the dynamic characteristics of the system, in terms of Campbell Diagram, Decay rate plot and Unbalance Response. Many researchers adopted different methodology for obtaining the model reduction but their work is limited up to undamped system. This work is started by motivation of the absentia of work for damped rotor bearing system.
Experimental Investigations on Heat Transfer Enhancement in a Horizontal Tube Using Converging and Diverging Conical Strips
Authors: Somanchi Naga Sarada , Rangisetty Sri Rama Devi , Bellam Sudheer PremKumar , Gugulothu Ravi , Bellam Samuel
Published: February 2015

The present work deals with the results of the experimental investigations carried out on augmentation of turbulent flow heat transfer in a horizontal circular tube by means of tube inserts, with air as working fluid.

Experiments were carried out initially for the plain tube (without tube inserts). The Nusselt number and friction factor obtained experimentally were validated against those obtained from theoretical correlations.

Secondly experimental investigations using six kinds of tube inserts namely Rectangular bar with diverging conical strips, Rectangular bar with converging conical strips, Rectangular bar with alternate converging diverging conical strips, Rectangular bar with holes and diverging conical strips, Rectangular bar with holes and converging conical strips and Rectangular bar with holes and alternate converging diverging conical strips were carried out to estimate the enhancement of heat transfer rate for air in the presence of inserts. The Reynolds number ranged from 8000 to 19000. In the presence of inserts, Nusselt number and pressure drop increased, overall enhancement ratio is calculated to determine the optimum geometry of the tube insert.

Based on experimental investigations, it is observed that, the enhancement of heat transfer using Rectangular bar with diverging conical strips is more effective compared to other inserts.
Neural Predictive Controller for Hydraulic Power Transmission in Wind Turbine
Authors: Mehta Akshan Paresh , Karthikeyan Ganesh Ram Ramanujam , Venkatesan Kalaichelvi , Ramanujam Karthikeyan
Published: February 2015

Fluid power transmission for wind turbines is quietly gaining more interest. The aerodynamic torque of the rotor blades is converted into a pressurized fluid flow by means of a positive displacement pump. At the other end of the fluid power circuit, the pressurized flow is converted back to torque and speed by a hydraulic motor. The goal of this paper is to develop a general dynamic model of a fluid power transmission for wind turbines, in order to gain better insight on the dynamic behavior and to explore the influence of the main design parameters. A fluid power transmission is modeled for a wind turbine with 1MW rated power capacity. This mathematical model can be used for simulation of the process using AUTOMATION STUDIO 5.2. Further the model has been approximated as a transfer function model using system identification toolbox available in MATLAB software. Neural network based predictive control (NPC) is applied to the mid-sized hydrostatic wind turbine model for maximizing power capture. The effectiveness of NPC is compared with PI controller.