bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature and Origin of “Squirting” in Female Sexuality
Authors: Salama Samuel , Boitrelle Florence , Gauquelin Amélie , Malagrida Lydia , Thiounn Nicolas , Desvaux Pierre
Published: December 2014

Introduction

During sexual stimulation, some women report the discharge of a noticeable amount of fluid from the urethra, a phenomenon also called “squirting.” To date, both the nature and the origin of squirting remain controversial. In this investigation, we not only analyzed the biochemical nature of the emitted fluid, but also explored the presence of any pelvic liquid collection that could result from sexual arousal and explain a massive fluid emission.

Methods

Seven women, without gynecologic abnormalities and who reported recurrent and massive fluid emission during sexual stimulation, underwent provoked sexual arousal. Pelvic ultrasound scans were performed after voluntary urination (US1), and during sexual stimulation just before (US2) and after (US3) squirting. Urea, creatinine, uric acid, and prostatic-specific antigen (PSA) concentrations were assessed in urinary samples before sexual stimulation (BSU) and after squirting (ASU), and squirting sample itself (S).

Results

In all participants, US1 confirmed thorough bladder emptiness. After a variable time of sexual excitation, US2 (just before squirting) showed noticeable bladder filling, and US3 (just after squirting) demonstrated that the bladder had been emptied again. Biochemical analysis of BSU, S, and ASU showed comparable urea, creatinine, and uric acid concentrations in all participants. Yet, whereas PSA was not detected in BSU in six out of seven participants, this antigen was present in S and ASU in five out of seven participants.

Conclusions

The present data based on ultrasonographic bladder monitoring and biochemical analyses indicate that squirting is essentially the involuntary emission of urine during sexual activity, although a marginal contribution of prostatic secretions to the emitted fluid often exists.
Asexuality: An Extreme Variant of Sexual Desire Disorder?
Authors: Brotto Lori A. , Yule Morag A. , Gorzalka Boris B.
Published: December 2014

Introduction

Human asexuality is defined as a lack of sexual attraction to anyone or anything. Various theories have been proposed to explain how asexuality should best be classified, and some have maintained that asexuality is an extreme variant of hypoactive sexual desire disorder (HSDD)—a sexual dysfunction characterized by a lack of interest in sex and significant distress. To date, this has never been empirically examined.

Aim and Method

Using measures of sexual desire and behavior, sex-related distress, personality, and psychopathology, the aim of the current study was to compare individuals scoring above the cutoff for asexuality identification (AIS >40) (n = 192) to sexual individuals (n = 231). The sexual group was further divided into a control group (n = 122), a HSDD group (n = 50), and a group with symptoms of low desire that were nondistressing (n = 59).

Results

Analyses were controlled for age. Individuals in the AIS >40 group had a greater likelihood of never previously engaging in sexual intercourse, fantasies, or kissing and petting than all other groups and a lower likelihood of experiencing sex-related distress than those with HSDD. For women, those in the HSDD and AIS >40 groups had significantly lower desire than the subclinical HSDD and control groups. Men in the AIS >40 group had significantly lower desire than the other three groups. Symptoms of depression were highest among those with subclinical HSDD and HSDD, whereas there were no group differences on alexithymia or desirable responding. A binary logistic regression indicated that relationship status (long-term dating/married), sexual desire, sex-related distress, and lower alexithymia scores were the best predictors of group membership (HSDD vs. AIS >40).

Conclusion

Taken together, these results challenge the speculation that asexuality should be classified as a sexual dysfunction of low desire.
Land‐use intensity and host plant identity interactively shape communities of arbuscular mycorrhizal fungi in roots of grassland plants
Authors: Vályi Kriszta , Rillig Matthias C. , Hempel Stefan
Published: December 2014

We studied the effect of host plant identity and land‐use intensity (LUI) on arbuscular mycorrhizal fungi (AMF, Glomeromycota) communities in roots of grassland plants. These are relevant factors for intraradical AMF communities in temperate grasslands, which are habitats where AMF are present in high abundance and diversity. In order to focus on fungi that directly interact with the plant at the time, we investigated root‐colonizing communities.

Our study sites represent an LUI gradient with different combinations of grazing, mowing, and fertilization. We used massively parallel multitag pyrosequencing to investigate AMF communities in a large number of root samples, while being able to track the identity of the host.

We showed that host plants significantly differed in AMF community composition, while land use modified this effect in a plant species‐specific manner. Communities in medium and low land‐use sites were subsets of high land‐use communities, suggesting a differential effect of land use on the dispersal of AMF species with different abundances and competitive abilities.

We demonstrate that in these grasslands, there is a small group of highly abundant, generalist fungi which represent the dominating species in the AMF community.
Deontic Modals: Why Abandon the Classical Semantics?
Authors: Horty John
Published: December 2014

I begin by reviewing classical semantics and the problems presented by normative conflicts. After a brief detour through default logic, I establish some connections between the treatment of conflicts in each of these two approaches, classical and default, and then move on to consider some further issues: priorities among norms, or reasons, conditional oughts, and reasons about reasons.
Preference‐Conditioned Necessities: Detachment and Practical Reasoning
Authors: Lauer Sven , Condoravdi Cleo
Published: December 2014

This article is about conditionalized modal statements whose antecedents concern a preferential attitude of an agent. The focus is on anankastic conditionals or, as they are known in the philosophical literature, hypothetical imperatives. We present a linguistically‐motivated analysis of anankastic and related conditionals and use it to address challenges for semantic theories of natural language conditionals motivated by certain philosophical concerns about practical reasoning and the requirements of rationality.
The Impact of a National Guideline on the Management of Cancer Pain on the Practice of Pain Assessment and Registration
Authors: Besse Kees , Vernooij‐Dassen Myrra , Vissers Kris , Engels Yvonne
Published: December 2014

The Dutch clinical practice guideline on the diagnosis and management of pain in patients with cancer was published in 2008 and intensively promoted to healthcare professionals who see patients with cancer. One of the most important recommendations is the systematic registering of the pain and its intensity. To evaluate in which degree this part of the practice guideline is implemented, we analyzed the medical records of patients attending the outpatient oncological clinic in an academic hospital, a large teaching hospital, and 4 smaller peripheral hospitals.

None of the participating hospitals assessed pain by a standardized scale. Reference to pain in the medical record happened more frequently in the academic hospital than in the other hospitals. The frequency of recording pain in the medical record in the academic hospital was much higher in this study than the one previously reported, whereas the findings in the other hospitals were comparable. There may be several reasons for the difference in reporting rate of pain in patients with cancer. Our findings indicate that the clinical practice guideline with regard to pain registration is poorly implemented in oncology outpatient clinics.

More efforts should be made to generate the awareness for the need of pain registration.
Opening Enediyne Scissors Wider: pH‐Dependent DNA Photocleavage by meta‐Diyne Lysine Conjugates
Authors: Kaya Kemal , Johnson Madeleine , Alabugin Igor V.
Published: December 2014

Photochemical activation of meta‐diynes incapable of Bergman and C1–C5 cyclizations still leads to efficient double‐strand DNA cleavage. Spatial proximity of the two arylethynyl groups is not required for efficient DNA photocleavage by the enediyne‐lysine conjugates. Efficiency of the cleavage is a function of the external pH and DNA damage is strongly enhanced at pH < 7. The pH‐dependence of the DNA photocleavage activity stems from the protonation states of lysine amino groups, the internal electron donors responsible for intramolecular PET quenching and deactivation of the photoreactive excited states. DNA‐binding analysis suggests intercalative DNA binding for phenyl substituted conjugate and groove binding for TFP‐substituted conjugate. Additional insights in the possible mechanism for DNA damage from the ROS (Reactive Oxygen Species) scavenger experiments found that generation of singlet oxygen is partially involved in the DNA damage.
The embodied brain
Authors: Fabiani Monica
Published: December 2014

In this editorial, I discuss the advantages of interpreting brain data in the context of other bodily systems. I also discuss current research challenges that may greatly benefit from a psychophysiological approach in which multiple methods—both peripheral and central—are used to improve our understanding of brain function, its underlying physiology, and its relationship to psychological constructs. In closing, I summarize the major changes and policy highlights regarding papers published in Psychophysiology.
A Case of Bronze Turkey Twins Developing from Hatching
Authors: Damaziak K , Michalczuk M , Zdanowska‐Sąsiadek Ż , Niemiec J
Published: December 2014

Contents

A double‐yolked egg that was laid by an 11‐month‐old bronze turkey hen on 2 April, 2013 was reported. The presented case of developing turkey twin embryos is the first ever described case for this species. The egg weighed 125 g and had 74.6 mm in length and 53.0 mm in width. The embryos died between the 23rd and 24th day of incubation. Both twin 1 and twin 2 were fully developed with body weights of: 37.7 g and 40.3 g, respectively. The likely causes of death include inappropriate arrangement of embryos and insufficient gas exchange in the last period of incubation. The embryos were arranged along the long axis of the egg, one underneath the other, and were closely adhering to one another. The twins were different in plumage pigmentation. In twin 1, a spontaneous mutation of plumage pigmentation (B) was observed, whereas twin 2 showed appropriate pigmentation (b+) in respect to parents.
Partitioning of Dietary Metal Intake—A Metal Dietary Exposure Screening Tool
Authors: Tran* Nga L. , Barraj Leila M. , Scrafford Carolyn , Bi Xiaoyu , Troxell Terry
Published: December 2014

Detection of heavy metals at trace or higher levels in foods and food ingredients is not unexpected given the widespread unavoidable presence of several metals in nature, coupled with advancement in analytical methods and lowering limits of detection. To assist risk managers with a rapid risk assessment when facing these situations, a metal dietary exposure screening tool (MDEST) was developed. The tool uses food intake rates based on the National Health and Nutrition Examination Survey 2005–2010 consumption data for the U.S. population two+ years and up and for infants age six months to <two years based on the Nestlé Feeding Infants and Toddlers Study, and existing exposure limits for several frequently detected metals (e.g., inorganic arsenic, cadmium, chromium, lead, and mercury). The tool has data entry fields for detected concentrations and includes algorithms that combine metal levels with consumption data to generate screening‐level exposure estimates, which it then compares to MDEST assigned default portions of the exposure limits in the risk characterization module. As a screening‐level tool, the risk assessment output is intentionally conservative, public health protective, and useful for a rapid assessment to set aside issues that are not of concern. Issues that cannot be readily resolved using this screening tool will need to be further evaluated with more refined input data that are tailored to the specific question or situation under consideration.
Treatment for a eumycetoma infection caused by Aspergillus in an immunocompromised host: a case report
Authors: Hopps S. , Roach A. , Yuen C. , Borders E.
Published: December 2014

Eumycetoma is a chronic infection of the skin and subcutaneous tissue caused by filamentous fungi, which usually occurs in tropical or subtropical countries. We report a case of an immunocompromised patient presenting with presumed eumycetoma in the United States and his subsequent treatment with voriconazole. The use of voriconazole and liposomal amphotericin B halted the progression and allowed gradual resolution of the infection. The patient will require close monitoring and long‐term therapy with voriconazole to obtain a clinical cure. Voriconazole and liposomal amphotericin B are potential initial treatment options, with long‐term voriconazole maintenance therapy, for an Aspergillus‐induced eumycetoma.
Human papillomavirus‐related high‐grade squamous intraepithelial lesions of the esophagus, skin, and cervix in an adolescent lung transplant recipient: a case report and literature review
Authors: Freiberger D. , Lewis L. , Helfand L.
Published: December 2014

High‐risk (carcinogenic) genotype human papillomavirus (HPV) infections can be associated with significant morbidity in the immunocompromised solid organ transplant (SOT) recipient. Immunosuppression‐associated persistent infection can predispose to the development of rapidly progressive high‐grade squamous intraepithelial lesions (HSIL) in this population. We present a case report of an adolescent bilateral lung transplant recipient who developed HSIL of the esophagus, cervix, and skin secondary to HPV. This review highlights the unique developmental needs of the sexually active adolescent SOT recipient and reviews guidelines for HPV‐related screening and education of this population.
Increased numbers of peripheral blood CD34+ cells in dogs with canine atopic dermatitis
Authors: Bruet Vincent , Lieubeau Blandine , Herve Julie , Roussel Anne , Imparato Laëtitia , Desfontis Jean‐Claude , Bourdeau Patrick
Published: December 2014

Background

The bone marrow may be involved in human atopic diseases, as shown by the release of CD34+ cells into the peripheral blood.

Hypothesis/Objectives

The aim was to determine the numbers of CD34+ cells in atopic dogs.

Animals

The following three groups of dogs were studied: 27 dogs with nonfood‐induced atopic dermatitis (NFICAD); 16 dogs with nonallergic inflammatory diseases; and 13 healthy control dogs.

Methods

Dogs with NFICAD were selected after fulfilment of Favrot's criteria and exclusion of other pruritic dermatoses, including flea infestation and adverse reaction to foods. The Canine Atopic Dermatitis Extent and Severity Index (CADESI)‐03 and a Visual Analog Scale (VAS) score for pruritus were used to quantify clinical signs. A phycoerythrin‐conjugated anticanine CD34 antibody was used to stain peripheral blood CD34+ cells, and these were enumerated using a flow cytometer. The CD34+ cell counts were compared between groups and tested (in the NFICAD group) for correlation with the severity of clinical signs.

Results

The numbers of peripheral CD34+ cells in dogs with NFICAD (median 1.7) were statistically higher than in dogs with other nonallergic inflammatory diseases (median 1.0; P = 0.01) and healthy control dogs (median 0.9; P = 0.009). In dogs with NFICAD, there was no correlation between CD34+ cell numbers and CADESI‐03 scores or owner‐assessed pruritus (VAS score).

Conclusions and clinical importance

The results of this study suggest the possible involvement of CD34+ cells in dogs with NFICAD. The role of CD34+ cells in the aetiopathogenesis of canine atopic dermatitis remains to be determined.
Twenty-Four Hour Solar Irradiance Forecast Based on Neural Networks and Numerical Weather Prediction
Authors: Cornaro C. , Bucci F. , Pierro M. , Del Frate F. , Peronaci S. , Taravat A.
Published: December 2014

In this paper, several models to forecast the hourly solar irradiance with a day in advance using artificial neural network techniques have been developed and analyzed. The forecast irradiance is the one incident on the plane of the modules array of a photovoltaic plant. Pure statistical (ST) models that use only local measured data and model output statistics (MOS) approaches to refine numerical weather prediction data are tested for the University of Rome “Tor Vergata” site. The performance of ST and MOS, together with the persistence model (PM), is compared. The ST models improve the performance of the PM of around 20%. The combination of ST and NWP in the MOS approach gives the best performance, improving the forecast of approximately 39% with respect to the PM.
Saturation Boiling Critical Heat Flux of PF-5060 Dielectric Liquid on Microporous Copper Surfaces
Authors: El-Genk Mohamed S. , Ali Amir F.
Published: December 2014

Pool boiling experiments are performed to investigate potential enhancement of critical heat flux (CHF) of PF-5060 dielectric liquid on microporous copper (MPC) surfaces and the effect of surface inclination angle. The morphology and microstructure of the MPC surfaces change with thickness. The experiments tested seven 10 × 10 mm MPC surfaces with thicknesses from 80 to 230 μm at inclination angles of 0 deg (upward facing), 60 deg, 90 deg (vertical), 120 deg, 150 deg, 160 deg, 170 deg, and 180 deg (downward facing). CHF increases as the thickness of the surface increases and/or the inclination angle decreases. The values in the upward facing orientation are 36–59% higher than on smooth Cu. For all surfaces, CHF values in the downward facing orientation are approximately 28% of those in the upward facing orientation. A developed CHF correlation, similar to those of Zuber and Kutateladze, accounts for the effects of inclination angle and thickness of the MPC surfaces. It is in good agreement with experimental data to within ±8%. Still photographs of nucleate boiling on the MPC surfaces at different inclinations help the interpretation of the experimental results.
Thickness Measurement of MCrAlY High-Temperature Coatings by Frequency Scanning Eddy Current Technique
Authors: Antonelli Giampiero , Ruzzier Marco , Necci Fiorenzo
Published: December 2014

Nondestructive characterization of non-serviced high-temperature coatings can be considered one of the important factors to achieve a higher level of structural integrity of advanced gas turbines.

The present paper describes an innovative eddy current technique especially developed for measuring the thickness of metallic (MCrAlY) coatings applied by vacuum plasma spray on Ni-base superalloys. Conventional eddy current techniques, well established for quality control of coating thickness, are not applicable in this case because of the low difference of electrical conductivities of conting and base materials, which is a consequence of their quite similar physical and chemical properties.

The new technique employs fast frequency scanning of the electromagnetic field in the range 100 kHz – 10 MHz, corresponding to probing depths from 1 mm to 0.1 mm. Dedicated hardware has been developed, featuring high sensitivity, stability and harmonic rejection.

Analysis of the measured data (i.e. probe impedance vs frequency), in order to estimate the relevant diagnostic parameters (coating thickness, coating and base metal electrical conductivities), is carried out on the basis of a theoretical model of interaction between a plane electromagnetic wave and test piece.

The results of tests performed on a non-serviced first stage blade are reported and compared with reference destructive data. Reliability, accuracy and practical applicability of the method meets the requirements for in-shop quality control.
Comparison of Sweep and Dihedral Effects on Compressor Cascade Performance
Authors: Sasaki T. , Breugelmans F.
Published: December 2014

The influence of two stacking lines, namely sweep and dihedral, has been investigated in a linear compressor cascade. Both types of blades considered are symmetrical about midspan and consist of a straight central section with either swept or dihedral sections towards the endwalls. Two types of experiments have been carried out.

Firstly, a parametric study was performed by changing both the magnitude and the extent of the sweep or dihedral. In the case of swept blades, those with forward sweep (SWF), for which the stacking line is swept in the upstream direction towards the endwall, were found to have better performance than backward swept blades. Subsequently, four sets of SWFs were compared. In the case of dihedral blades, it is well-known that the dihedral is advantageous when the angle between the suction surface and the endwall is obtuse, i.e. positive dihedral. Thus, four sets of positive dihedral blades (DHP) were compared. In both SWF and DHP blades, those configurations which have better efficiency than straight blades were determined.

Secondly, detailed three-dimensional measurements inside the blade passage were performed in the cases which showed the best performance in the parametric study. Both SWF and DHP showed significant effects on the flowfield. In the SWF case, a vortex, which has the opposite sense to the passage vortex, was observed in the forward portion inside the blade passage. This vortex supplies high-energy fluid to the endwall region and reduces the corner stall. The secondary flow is greatly reduced. In the DHP, the blade loading was reduced at the endwall and increased at the midspan. Also reduction of the corner stall and the secondary flow was observed.
Investigation of Vapor-Phase Lubrication in a Gas Turbine Engine
Authors: Van Treuren Kenneth W. , Barlow D. Neal , Heiser William H. , Wagner Matthew J. , Forster Nelson H.
Published: December 2014

The liquid oil lubrication system of current aircraft jet engines accounts for approximately 10–15% of the total weight of the engine. It has long been a goal of the aircraft gas turbine industry to reduce this weight. Vapor-Phase Lubrication (VPL) is a promising technology to eliminate liquid oil lubrication. The current investigation resulted in the first gas turbine to operate in the absence of conventional liquid lubrication. A phosphate ester, commercially known as DURAD 620B, was chosen for the test. Extensive research at Wright Laboratory demonstrated that this lubricant could reliably lubricate railing element bearings in the gas turbine engine environment. The Allison T63 engine was selected as the test vehicle because of its small size and bearing configuration. Specifically, VPL was evaluated in the number eight bearing because it is located in a relatively hot environment, in line with the combustor discharge, and it can be isolated from the other bearings and the liquid lubrication system. The bearing was fully instrumented and its performance with standard oil lubrication was documented. Results of this baseline study were used to develop a thermodynamic model to predict the bearing temperature with VPL. The engine was then operated at a ground idle condition with VPL with the lubricant misted into the #8 bearing at 13 ml/hr. The bearing temperature stabilized at 283°C within 10 minutes. Engine operation was continued successfully for a total of one hour. No abnormal wear of the rolling contact surfaces was found when the bearing was later examined. Bearing temperatures after engine shutdown indicated the bearing had reached thermodynamic equilibrium with its surroundings during the test. After shutdown bearing temperatures steadily decreased without the soakback effect seen after shutdown in standard lubricated bearings. In contrast, the oil lubricated bearing ran at a considerably lower operating temperature (83°C) and was significantly heated by its surroundings after engine shutdown. In the baseline tests, the final bearing temperatures never reached that of the operating VPL system.
Effect of Fuel Moisture Content on Biomass-IGCC Performance
Authors: Hughes Wendy E. M. , Larson Eric D.
Published: December 2014

The moisture level in biomass fuels potentially impacts efficiency in conversion to power. This paper examines the efficiency and net power output of a circulating fluidized bed gasifier-combined cycle with flue gas drying for a range of as-received raw biomass moisture contents and levels of pre-gasification drying. Due to the lack of empirical data available, a modeling approach is used to simulate the effect of varying moisture content in the gasifier feed biomass. Below 30%, the raw-biomass moisture content has a negligible effect on the cycle efficiency and net power output. Higher moisture contents significantly reduce cycle efficiency. For a specified as-received biomass moisture content, drying prior to gasification increases overall efficiency, but the gains in efficiency decrease with increasing levels of drying.
A High Temperature Assessment of Air-Cooled Unsteady Pressure Transducers
Authors: Ferguson Derek G. , Ivey Paul C.
Published: December 2014

This paper discusses the problem of measuring unsteady pressure in a high temperature environment using standard transducers. Commercially available cooling adapters for these transducers use water as the cooling medium to provide thermal protection. This arrangement is suitable only for some test bed applications and not suitable for integration into inflight active control systems.

An assessment of the cooling effectiveness of a commercial water cooled adapter using air as the cooling medium is presented using an experimentally validated finite element heat transfer model. The assessment indicates survival of an air-cooled transducer, itself rated to 235°C, at source flow temperatures up to 800°C.
Experimental Investigation of Stepped Tip Gap Effects on the Performance of a Transonic Axial-Flow Compressor Rotor
Authors: Thompson Donald W. , King Paul I. , Rabe Douglas C.
Published: December 2014

The effects of stepped tip gaps and clearance levels on the performance of a transonic axial-flow compressor rotor were experimentally determined. A two-stage compressor with no inlet guide vanes was tested in a modern transonic compressor research facility. The first-stage rotor was unswept and was tested for an optimum tip clearance with variations in stepped gaps machined into the casing near the aft tip region of the rotor. Nine casing geometries were investigated consisting of three step profiles at each of three clearance levels. For small and intermediate clearances, stepped tip gaps were found to improve pressure ratio, efficiency, and flow range for most operating conditions. At 100% design rotor speed, stepped tip gaps produced a doubling of mass flow range with as much as a 2.0% increase in mass flow and a 1.5% improvement in efficiency. This study provides guidelines for engineers to improve compressor performance for an existing design by applying an optimum casing profile.
A Comparison of Experimental Rotordynamic Coefficients and Leakage Characteristics Between Hole-Pattern Gas Damper Seals and a Honeycomb Seal
Authors: Yu Zeping , Childs Dara W.
Published: December 2014

Honeycomb annular seals are an attractive design alternative due to their superior static and dynamic performance. However, their implementation in industrial practice has been delayed by the following characteristics: a) manufacturing time can be appreciable, and b) they can seriously damage the shaft if rubbing occurs. To minimize these problems, “hole-pattern” gas damper seals, which are formed by simply drilling holes into an annular smooth seal, were manufactured and tested. The hole-pattern damper seal stator can be made of high-strength plastic materials which are less likely to damage a shaft during rubbing. The experimental results presented demonstrate that, compared to a honeycomb seal, a hole-pattern damper seal with 3.18 mm hole diameters and a high percentage of hole surface has achieved: (a) an average of 12 percent reduction in leakage rate, and (b) considerably higher effective damping, especially under high speeds and low inlet pressure ratio conditions.
Imbalance Response of a Test Rotor Supported on Squeeze Film Dampers
Authors: San Andrés Luis , Lubell Daniel
Published: December 2014

Squeeze film dampers (SFDs) provide vibration attenuation and structural isolation to aircraft gas turbine engines which must be able to tolerate larger imbalances while operating above one or more critical speeds. Rotor-bearing-SFD systems are regarded in theory as highly nonlinear, showing jump-phenomena and even chaotic behavior for sufficiently large levels of rotor imbalance. Yet, few experimental results of practical value have verified the analytical predictions. A test rig for measurement of the dynamic forced response of a three-disk rotor (45 kg) supported on two cylindrical SFDs is described. The major objective is to provide a reliable data base to validate and enhance SFD design practice and to allow a direct comparison with analytical models. The open-ends SFD are supported by four-bar centering structures each with a stiffness of 3.5 MN/m. Measured synchronous responses to 9,000 rpm due to various imbalances show the rotor-SFD system to be well damped with amplification factors between 1.6 and 2.1 while traversing cylindrical and conical modes critical speeds. The rotor amplitudes of motion are found to be proportional to the imbalances for the first mode of vibration, and the damping coefficients extracted compare reasonably well to predictions based on the full-film open-ends SFD. Tight lip (elastomeric) seals contribute greatly to the overall damping of the test rig. Measured dynamic pressures at the squeeze film lands are well above ambient values with no indication of lubricant dynamic cavitation as simple theoretical models dictate. The measurements show absence of non-linear behavior of the rotor-SFD apparatus for the range of imbalances tested.

• The research program is a joint effort funded by the National Science Foundation (NSF) and the TAMU Turbomachinery Research Consortium (TRC).
Experimental and Numerical Conjugate Flow and Heat Transfer Investigation of a Shower-Head Cooled Turbine Guide Vane
Authors: Bohn Dieter E. , Becker Volker J. , Rungen Agnes U.
Published: December 2014

This paper presents investigations of the development for a shower-head cooling configuration for a modern industrial turbine guide vane. One aim is to find suitable locations for cooling gas ejection with the lowest cooling gas mass flow possible. The investigations begin with a numerical experiment. After the prediction of a suitable configuration and operating parameters, the aerodynamics are investigated experimentally using a non-intrusive LDA technique.

Once the aerodynamics had been validated, the numerical experiments were expanded to a thermal analysis of the vane. Our conjugate flow and heat transfer simulation enables thermal analysis of the vane body without us having to derive any heat transfer data beforehand. The calculations were performed for a temperature ratio of 0.5 between cooling gas and main stream. This temperature ratio is similar to the operating conditions found in current designs.

The stagnation line moves under the influence of cooling gas ejection, which significantly influences the cooling gas distribution on the vane surface. The temperature distribution inside the vane is compared to a non-cooled test case. The simulation shows that the temperature peaks at the leading edge are reduced by between 18% and 44%.
Loading Software to Engine Controls in the Field
Authors: Beecher Scott F. , Lynch Bret G.
Published: December 2014

With the advent of electronically alterable memories in electronic gas turbine engine control systems, there is now the opportunity for updating software in the field. Field loading provides a means to economically correct problems or introduce enhancements to system operation through the electronic control. In this paper we describe the characteristics of high integrity reprogramming systems used to update engine controls in-the-field.

Pratt & Whitney Aircraft supports two methods for in-service reprogramming of Electronic Engine Controls (EECs), These two methods are PC Laptop based loaders and ARINC loaders. This discussion will focus on the capabilities provided to support in-the-field reprogramming of engine controls. The flexibility, integrity, and the benefits of field reprogramming provided by these software loading systems will be explained. These reprogramming systems provide a PC based application and ARINC based systems for either on-wing reprogramming or on-board reprogramming directly from a flight deck device to the EEC.

The PC Loader reprogramming utilities allow field personnel to reprogram engine control application software and/or constants and configuration information using a suitably equipped IBM PC or compatible computer. These utilities are intended to be operated per Service Bulletin authorization only. They require a PC compatible computer (presumably a laptop model) with 2 UART interface cards, an interfacing cable, and the new software to be loaded. The rigor and manner of the integrity checks to ensure proper loading of the control is essential to an acceptable loading system.

There are two types of ARINC-based loaders: on-wing loaders and on-board loaders. Both types enable the operator to upload application, trim, and/or configuration software to the engine control. Additionally the ARINC 615 device allows operators to download fault and configuration data from the control. Each type of loader uses a specially formatted file to control the sequence of operations involved in a data loading session. The on-wing loader utilizes a specially designed portable data loader which connects directly to the EEC via dedicated cabling through the control’s ARINC connectors. This type of data loader contains software which communicates via an ARINC 615 protocol to a peer software entity running on the EEC. The on-board loader uses the aircraft’s central maintenance computer system to communicate with the EEC over the aircraft’s ARINC 629 data bus. It also operates using a peer-to-peer communication protocol with the EEC. The ARINC 629 loader requires no extra equipment or cabling, nor does it require the EEC to be accessible for attachment of cables.
Calibration of an 8-Pole Planar Radial Magnetic Actuator
Authors: Fittro Roger L. , Baun Dan O. , Maslen Eric H. , Allaire Paul E.
Published: December 2014

Force versus coil currents and air gap measurements were obtained for an 8-pole planar radial magnetic actuator constructed from laminated silicon iron. Static force measurements were made for journal eccentricities up to 2/3 of the nominal actuator radial clearance and various coil currents spanning the expected operating range. Three theoretical force models of varying degrees of complexity were developed using magnetic circuit theory and constant magnetic material properties. All three models were used to reduce the experimental data and an optimized expression representing the actuator force as a function of journal position and stator coil currents was found. The resulting optimized calibration model produced a proportionality constant and equivalent iron length significantly different from theoretically determined values, 29% and 130% greater respectively.

A detailed error analysis was conducted to quantify the uncertainty in the bearing calibration relationship such that uncertainty bounds can be applied to the in situ actuator force measurements.

Hysteresis testing was conducted for various journal positions. Hysteresis effects were shown to be approximately 2% of the peak force when comparing the differences between the actuator force as the currents were increasing and the forces generated when the currents were decreasing. The actuator frequency response was also examined. An actuator bandwidth of at least 700 Hz was determined. Above 700 Hz the actuator frequency response could not be distinguished from the test fixture frequency response.
Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part I — Stick-Slip Contact Kinematics
Authors: Yang B. D. , Menq C. H.
Published: December 2014

Friction dampers are often used in turbine design to attenuate blade vibration to acceptable levels so as to prolong blades’ service life. A wedge damper, also called a self-centering blade-to-blade damper, can provide more design flexibility to meet various needs in different operating conditions when compared with conventional platform dampers. However, direct coupling of the two inclined friction interfaces of the wedge damper often leads to very complex contact kinematics. In Part I of this two-part paper, a dual-interface friction force model is proposed to investigate the coupling contact kinematics. The key issue of the model formulation is to derive analytical criteria for the stick-slip transitions that can be used to precisely simulate the complex stick-slip motion and, thus, the induced friction force as well. When considering cyclic loading, the induced periodic friction forces can be obtained to determine the effective stiffness and damping of the interfaces over a cycle of motion. In Part II of this paper, the estimated stiffness and damping are then incorporated with the harmonic balance method to predict the forced response of a blade constrained by wedge dampers.
Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part II — Prediction of Forced Response and Experimental Verification
Authors: Yang B. D. , Menq C. H.
Published: December 2014

In the second part of this paper, the application of the proposed dual-interface model to the prediction of the forced response of a blade constrained by wedge dampers will be presented. When considering cyclic loading, the induced friction forces and contact normal loads are combined so as to determine the effective stiffness and damping of the friction interfaces over a cycle of motion. The harmonic balance method is then used to impose the approximate stiffness and damping of the friction interfaces to a linear structure model of the blade. This approach results in a set of nonlinear algebraic equations that can be solved to yield the forced response of the blade excited by harmonic external forces. The predicted forced response can then be used to optimize a given damper design, namely to determine the dynamic weight at which the maximum reduction of resonant response is obtained. In order to illustrate the capacity of the proposed method and to examine its accuracy, the forced response of a test beam is examined. The prediction is also compared with the results of lab tests to validate the proposed dual-interface friction force model.
Computation of Multi-Passage Cascade Flows With Overset and Deforming Grids
Authors: Tuncer Ismail H. , Sanz Wolfgang
Published: December 2014

An overset grid method is applied to the solution of single and multi-passage cascade flows with a compressible Navier-Stokes solver. C-type grids around individual blades are overset onto a Cartesian background grid. Overset grids are allowed to move in time relative to each other as prescribed by the oscillatory plunging motion. The overset grid method uses a simple, robust numerical algorithm to localize moving boundary points and to interpolate solution variables across intergrid boundaries. Computational results and comparisons with single/staggered, deforming grid solutions are presented for in- and out-of-phase multi-passage flows through a compressor cascade. Very good agreement is obtained against the deforming grid solutions.
3-D Conjugate Flow and Heat Transfer Calculations of a Film-Cooled Turbine Guide Vane at Different Operation Conditions
Authors: Bohn Dieter E. , Becker Volker J. , Kusterer Karsten A.
Published: December 2014

Film-cooling has become a widely used cooling method in present day gas turbines. Cooling gas ejection at the leading edge serves to protect the entire vane surface from contact with the hot gas. Thus, material temperatures must be reduced in order to guarantee an economically acceptable life span of the vane.

Normally, thermal investigations are performed with frozen equilibrium temperature distributions for different operating points. Thus, the heat transfer interaction between the flow and the solid body is neglected. This influence is taken into account by a conjugate fluid flow and heat transfer method in the investigations to be presented. In the case of the aerodynamics, a solver for the 3-D full Navier-Stokes equations is employed. The numerical scheme works on the basis of an implicit finite volume method combined with a multi-block technique.

In the 3-D numerical experiment to be presented, the influence of leading edge cooling gas ejection on the temperature distribution to the vane material is investigated. The cooling air is ejected through two slots at the leading edge. 3-D aerodynamic investigations performed by Bohn et al. (1996a) have shown the influence of complex 3-D flow phenomena, e.g. secondary flow, on the distribution of the cooling air along the vane surface. Furthermore, 3-D thermal investigations for one operation point with a realistic temperature ratio of cooling air flow and main flow were presented by Bohn et al. (1996b).

The investigations were performed for three different flow angles in the non-ejection case and the film-cooled case in order to demonstrate the operation of the cooling method. The shift of the stagnation line significantly influences the cooling fluid distribution along the vane surface, something that has consequences for the thermal load of the vane. Furthermore, the results are compared to an investigation with a prescribed frozen equilibrium temperature distribution. It is shown that the vane temperature increases locally for over 10 K at different operating points. This increase is significant for the thermal design process and can only be detected using the conjugate fluid flow and heat transfer method.
Utilization of the Transient Liquid Crystal Technique for Film Cooling Effectiveness and Heat Transfer Investigations on a Flat Plate and a Turbine Airfoil
Authors: Drost U. , Bölcs A. , Hoffs A.
Published: December 2014

The transient liquid crystal technique has been used to measure film cooling effectiveness and heat transfer on a flat plate in a free jet, and a turbine airfoil in a linear cascade. A multiple-test regression method has been developed for the data reduction, considering a transient coolant temperature evolution. Flat plate film cooling was investigated for a single row of 35° inclined holes at Mach numbers of 0.3 and 0.5, and two turbulence intensities. Downstream of injection heat transfer was increased in-between the holes due to enhanced turbulence caused by the shearing of the coolant and the mainstream. At higher turbulence intensity the range of blowing ratios was broader as lift-off was delayed. Rim cooling measurements on the airfoil were conducted at engine-representative flow conditions. A maximum effectiveness of 0.3 behind injection was observed on the suction side, with slightly higher values for a double row in comparison to a single row configuration. Due to a high coolant momentum, the effectiveness on the pressure side was very low at about 0.05 for a single row configuration.
Identification of Gas Turbine Dynamics: Time-Domain Estimation Problems
Authors: Hill David C.
Published: December 2014

The characteristic form of a linear gas turbine model is examined. Time domain models are obtained from engine test data. Transfer function model estimates exhibit unrealistic pole positions. This is caused by systematic bias in the parameter estimates, coupled with high sensitivity of the poles to parameter errors. The bias is a result of using a measured fuel flow as the model input. This violates the requirement that the input be piece-wise constant. The problem is reduced using multiple-output state space models, which are less sensitive to small parameter errors.
Getting to Problem Definition
Authors: Luchun Charles J.
Published: December 2014

As the operational life of aircraft hardware increases, repetitions of phenomena previously explained as “isolated incidents” have been seen to occur. These problems are not necessarily application specific, nor material’s anomaly, nor design defect, nor operational abuse, nor any single cause, but, usually, an unfortunate combination of degradation in several of these factors, which becomes, statistically, more probable as the operational hours increase. Because they are rare, it can take years to collect enough clues to identify these links and synthesize the event.

When the problem involves an aging commercial aircraft turbine engine, that has passed from the designer to the manufacturer, and then to the airframer and the operator, through the hands of the maintainer, the repairer and the spare parts breakout supplier, the combinations of variables becomes too large to attack individually.

This paper characterizes a common sense approach to solving these problems. This approach favors a small team with a strong leader dedicated to that task. It is based on a theory that clues may be found in the history of the product and the industry, as well as in the exhibits and demographics of the incidents, and that a broad approach to fact finding, coupled with disciplined treatment of data, will allow the investigators to develop some intuitive sense of their problem, and facilitate linking of the pertinent facts.

This paper includes a hypothetical example, based on information in the public domain, of such a problem relating to an aging gas turbine engine. It is not meant to represent an actual case history, but is rather a combination of recognizable events, not uncommon, in either type or quantity, in the gas turbine industry, combined to illustrate this theory.
Incorporating Neural Networks Into Gas Turbine Performance Diagnostics
Authors: Kanelopoulos K. , Stamatis A. , Mathioudakis K.
Published: December 2014

Possibilities of incorporating neural nets in different tasks of a gas turbine performance diagnostic procedure are investigated. The purpose is to examine how neural nets can be implemented and what advantages they may offer. First, the possibility to constitute a performance model by using neural nets is considered. Different modes of operation are examined and the neural net architectures for achieving better accuracy are discussed. Subsequently, different problems of fault detection and identification are considered. Classification of faults is performed on the basis of diagnostic parameters produced by adaptive modelling. Both sensor faults and actual engine component faults are examined. A decision logic based on several neural nets is proposed. At a first level it is decided whether a fault exists, and if yes, checks are performed in order to identify the fault in as much detail as possible. Summarizing, the paper discusses different aspects of neural net implementation, in an effort to provide guidelines for application of this type of technique in the field of gas turbine diagnostics.