bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Class of Permanent Magnetic Materials for High Temperature Applications
Authors: Walmer Marlin S. , Chen Christina H. , Walmer Michael H.
Published: August 2014

A new class of Sm2TM17 type permanent magnetic materials has been developed to meet the needs of applications at high temperatures. These magnets have high to moderate energy product (BH)max, high intrinsic coercivity iHc with low temperature coefficient of iHc, and straight-line demagnetization curves up to 550°C. A straight-line demagnetization curve provides greater design flexibility and facilitates reduced size and weight of magnetic circuits. A straight-line demagnetization curve is even more important for dynamic and highly loaded applications where high demagnetization forces are encountered. Examples of dynamic applications include generators, motors, jet engine start generators, and electro-magnet actuators. Highly loaded applications include the periodic arrangement of magnets in traveling wave tubes. A new symbol, TM, is introduced, which is defined as the maximum temperature at which the demagnetization curve is a straight line. An important feature of these magnets with high TM is a lower temperature coefficient of iHc, β, which gives these magnets a great resistance to thermal demagnetization and leads to better performance at high temperatures. This paper reports the magnetic properties vs. temperature for this new class of magnets, and compares them to the best conventional magnets, in order to illustrate the improvements that have been made.
Influence Wave Mode Computations of Multi-Passage Cascade Flows
Authors: Tuncer Ismail H. , Weber Stefan
Published: August 2014

A Navier-Stokes solution method with overset grids is employed to compute the Influence Wave Modes of a compressor cascade in transonic flow conditions. The computed predictions are compared against the experimental data and the predictions based on Traveling Wave Mode computations performed using a different Navier-Stokes solver. In the present method, a five-passage flow domain is discretized with O-type subgrids around each blade and a rectangular background subgrid. A simple, robust numerical algorithm is used to localize moving intergrid boundary points, and to interpolate solution variables across the subgrids. The influence wave mode computation predicts a strong influence of the pitching mid-blade on the shock position of the neighboring blades. The predictions agree with the experimental data fairly well, and shows an improvement over the Traveling Wave Mode predictions.
Three-Dimensional Time-Resolved Flow Field in the First and Last Turbine Stage of a Heavy Duty Gas Turbine: Part I — Secondary Flow Field
Authors: von Hoyningen-Huene Martin , Frank Wolfram , Jung Alexander R.
Published: August 2014

Unsteady stator-rotor interaction in gas turbines has been investigated both experimentally and numerically for some years now. Even though the numerical methods are still in development, today they have reached a certain degree of maturity allowing industry to focus on the results of the computations and their impact on turbine design, rather than on a further improvement of the methods themselves. The key to increase efficiency in modern gas turbines is a better understanding and subsequent optimization of the loss-generation mechanisms. A major part of these are the secondary losses. To this end, this paper presents the time-resolved secondary flow field for the two test cases computed, viz the first and the last turbine stage of a modern heavy duty gas turbine. A companion paper referring to the same computations focuses on the unsteady pressure fluctuations on vanes and blades. The investigations have been performed with the flow solver ITSM3D which allows for efficient calculations that simulate the real blade count ratio. This is a prerequisite to simulate the unsteady phenomena in frequency and amplitude properly.
Three-Dimensional Time-Resolved Flow Field in the First and Last Turbine Stage of a Heavy Duty Gas Turbine: Part II — Interpretation of Blade Pressure Fluctuations
Authors: von Hoyningen-Huene Martin , Frank Wolfram , Jung Alexander R.
Published: August 2014

Unsteady stator-rotor interaction in gas turbines has been investigated experimentally and numerically for some years now. Most investigations determine the pressure fluctuations in the flow field as well as on the blades. So far, little attention has been paid to a detailed analysis of the blade pressure fluctuations. For further progress in turbine design, however, it is mandatory to better understand the underlying mechanisms. Therefore, computed space–time maps of static pressure are presented on both the stator vanes and the rotor blades for two test cases, viz the first and the last turbine stage of a modern heavy duty gas turbine. These pressure fluctuation charts are used to explain the interaction of potential interaction, wake-blade interaction, deterministic pressure fluctuations, and acoustic waveswith the instantaneous surface pressure on vanes and blades. Part I of this two-part paper refers to the same computations, focusing on the unsteady secondary now field in these stages. The investigations have been performed with the flow solver ITSM3D which allows for efficient simulations that simulate the real blade count ratio. Accounting for the true blade count ratio is essential to obtain the correct frequencies and amplitudes of the fluctuations.
Numerical Simulations of Three Dimensional Turbulent Flows in a Shrouded Backswept Impeller at Design and Off-Design Flow Rates Using Unstructured Grid Method
Authors: Zhang Chuhua , Miao Yongmiao , Gu Chuangang
Published: August 2014

The three-dimensional turbulent flow fields in a shrouded fan impeller with backswept discharge at three operating flow rates are numerically calculated with an unstructured grid method recently developed by the authors. Reynolds-averaged Navier-Stokes (N-S) equations and k-ε equations are solved through finite volume method with pressure correction algorithm. Numerical results are presented for detailed main and secondary flow velocity. The agreements of radial velocity component at different sections at design flow rate between computations and measurements are generally good. It can be observed that different flow rates have distinctive effects on flow patterns. At design flow rate, the flow is behaved as attached flow pattern and has a relatively smooth distribution for the main flow velocity. Above the design flow rate, a sudden drop and non-smooth distribution for the main flow velocity appear at the pressure-hub corner near the impeller inlet, however, the distribution of main flow velocity becomes smooth gradually downstream. Under the design flow rate, the jet-wake structure appears obviously within the impeller passage.
Analysis and Design Outlines of Centrifugal Compressor Inlet Volutes
Authors: Pazzi Simone , Michelassi Vittorio
Published: August 2014

The flow inside centrifugal compressor inlet volutes is studied by means of numerical and experimental approaches. The performance of a typical test geometry is briefly compared with experiments and the relative performance of the various proposed modifications is discussed in terms of flow distortion and loss coefficient. The flow is analyzed at the exit of the volute. The effects of modifications to the standard axi-symmetric geometry are evaluated. The study includes the effect of flow splitters, the number of which is found to considerably alter the flow field. The analysis also includes changes in the geometry aimed at a better redistribution of the mass in the tangential direction.
Design and Construction of a Transonic Test-Turbine Facility
Authors: Erhard J. , Gehrer A.
Published: August 2014

This paper describes the design concept and construction of a continuous operating cold flow transonic test turbine facility, which is a unique combination of a 2 MW axial test turbine and a direct coupled brake compressor. To cover the losses additional air is provided through a separate electrically driven compressor station and fed into the turbine inlet casing via special mixer inserts which are also fed by the hot compressed air from the brake compressor. The main test rig dimensions and its capabilities are outlined.

A brief description of the design process with step by step advanced technology design methods is presented from the first ideas up to the latest plant expansion for special testing conditions where two industrial transonic turbine stages will be tested. The aerodynamic and structural design of our transonic single turbine stage (TTM-Stage) is described in detail and the results of the respective flow simulations are presented.
Linear Deterministic Source Terms for Hot Streak Simulations
Authors: Orkwis Paul D. , Turner Mark G. , Barter John W.
Published: August 2014

Steady state surface rothalpy results obtained with a lumped deterministic source term are compared with results obtained from a traditional nonlinear inviscid unsteady solution for an aircraft engine first stage high-pressure turbine rotor configuration. Boundary condition/potential field effects and the order of accuracy of the available schemes are shown to have a significant effect on surface rothalpy results. However, the new technique demonstrates a significant potential for including unsteady effects in time average calculations with minimal computer effort.
Endwall Cavity Flow Effects on Gaspath Aerodynamics in an Axial Flow Turbine: Part II — Source Term Model Development
Authors: Hunter Scott D. , Orkwis Paul O.
Published: August 2014

Axial flow turbine designers are currently using Navier-Stokes flow solvers to reveal the details of the three dimensional flowfield inside individual bladerow passages. This new capability has allowed designers to focus on secondary flow reduction to improve turbine efficiency. These steady bladerow solvers include viscous and film cooling effects and show good agreement with test measurements in the midspan region. However, the difference between computational results and experimental data at the endwalls is significant due to the exclusion of endwall cavity effects. A clear understanding of how the cavity flow interacts with the gaspath aerodynamics, in conjunction with an accurate computational model, is needed to predict accurately the secondary flow patterns and endwall losses.

In Part I, the experimental and computational results from an investigation of the endwall cavity and gaspath flow interaction in a low pressure turbine were presented. Steady and unsteady computational analyses were utilized to model different combinations of the cavity and bladerow geometries. The data and computations confirmed that endwall cavity flows have a significant influence on gaspath aerodynamics and that these flows need to be included in bladerow computations for accurate results. However, the level of effort required to construct the computational grid and obtain a flow solution renders these computational models prohibitive.

In Part II, the development of a source term model for a steady bladerow solver that simulates endwall cavity flows in a low pressure turbine is reviewed. Different levels of model complexity were evaluated to determine the impact of endwall geometry and source term distributions on analysis accuracy. The source term model adequately captured endwall cavity effects and accurately predicted secondary flow in the adjacent bladerow. This source term model gives designers the capability to investigate new ideas of reducing secondary flow in a timely manner, leading to improvements in overall turbine efficiency.
A CFD Model for Real Gas Flows
Authors: Cravero Carlo , Satta Antonio
Published: August 2014

Numerical solutions of Navier-Stokes equations are nowadays widely used for several industrial applications in different fields (aerodynamic, propulsion, naval, combustion, etc..), but the solution methods still require significant improvements especially in two aspects: turbulence modeling and fluid modeling. The paper describes in some detail a real fluid model based on Redlich-Kwong-Aungier equation of state and its implementation into a Navier-Stokes solver developed by the authors for turbomachinery flows analysis.
A Test-Based Methodology for A Priori Selection of Gain/Phase Relationships in Proportional, Phase-Shifting Control of Combustion Instabilities
Authors: Vaudrey Michael A. , Saunders William R. , Eisenhower Bryan
Published: August 2014

Feedback control system design, for general single-in-single-out (SISO) applications, requires accurate knowledge of the loop transfer function. Active combustion control design is usually implemented using such SISO architectures, but is quite challenging because the thermoacoustic response results from a relatively unknown, self-excited system and nonlinear processes that must be understood before learning the gain/phase relationship of the system precisely at the instability frequency. However, recent experiments have shown that it is possible to obtain accurate measurements of the relevant loop transfer (frequency response) functions at frequencies adjacent to the instability frequency. Using a simple tube combustor, operating with a premixed, gaseous, burner-stabilized flame, the loop frequency response measurements have been used to develop a methodology that leads to ‘test-based predictions’ of the absolute phase settings and ‘best’ gain settings for a proportional, phase-shifting controller commanding an acoustic actuator in the combustor.

The contributions of this methodology are twofold. First, it means that a manual search for the required phase setting of the controller is no longer necessary. In fact, this technique allows the absolute value of controller phase to be determined without running the controller. To the authors’ knowledge, this has not been previously reported in the literature. In addition, the ‘best’ gain setting of the controller, based on this new design approach, can be defined as one that eliminates or reduces the limit cycle amplitude as much as possible within the constraint of avoiding generation of any controller-induced instabilities. (This refers to the generation of ‘new’ peaks in the controlled acoustic pressure spectrum.) It is shown that this tradeoff in limit cycle suppression and avoidance of controller-induced instabilities is a manifestation of the well-known tradeoff in the sensitivity/complementary sensitivity function for feedback control solutions. The focus of this article is limited to the presentation of the design method and does not discuss the detailed nonlinear phenomena that must be understood to determine the optimal gain/phase settings at the limit cycle frequency for a real (versus theoretical) combustor system. A companion paper describes how the proposed design method can be used to generate an AI controller that maintains stabilizing control for a range of changing operating conditions.
Demonstration of a Semi-Closed Cycle, Turboshaft Gas Turbine Engine
Authors: Meitner Peter L. , Laganelli Anthony L. , Senick Paul F. , Lear William E.
Published: August 2014

A semi-closed cycle, turboshaft gas turbine engine was assembled and tested under a cooperative program funded by the NASA Glenn Research Center with support from the U.S. Army. The engine, called HPRTE (High Pressure, Recuperated Turbine Engine), features two distinct cycles operating in parallel; an “inner,” high pressure, recuperated cycle, in which exhaust gas is recirculated, and an “open” through-flow cycle. Recuperation is performed in the “inner,” high pressure loop, which greatly reduces the size of the heat exchanger. An intercooler is used to cool both the recirculated exhaust gas and the fresh inlet air. Because a large portion of the exhaust gas is recirculated, significantly less inlet air is required to produce a desired horsepower level. This reduces the engine inlet and exhaust flows to less than half that required for conventional, open cycle, recuperated gas turbines of equal power. In addition, the reburning of the exhaust gas reduces exhaust pollutants.

A two-shaft engine was assembled from existing components to demonstrate concept feasibility. The engine did not represent an optimized system, since most components were oversized, and the overall pressure ratio was much lower than optimum. New cycle analysis codes were developed that are capable of accounting for recirculating exhaust flow. Code predictions agreed with test results. Analyses for a fully developed engine predict almost constant specific fuel consumption over a broad power range. Test results showed significant emissions reductions.

This document is the first in a series of papers that arc planned to be presented on semi-closed cycle characteristics, issues, and applications, addressing the impact of recirculating exhaust flow on combustion and engine components.
Hybrid Heat Engines: The Power Generation Systems of the Future
Authors: Layne Abbie , Samuelsen Scott , Williams Mark , Hoffman Patricia
Published: August 2014

A hybrid heat engine results from the fusion of a heat engine with a non-heat-engine based cycle (unlike systems). The term combined cycle, which refers to similar arrangements, is reserved for the combination of two or more heat engines (like systems). The resulting product of the integration of a gas turbine and a fuel cell is referred to here as a hybrid heat engine or “Hybrid” for short.

The intent of this paper is to provide, to the gas turbine community, a review of the present status of hybrid heat engine technologies. Current and projected activities associated with this emerging concept are also presented. The National Energy Technology Laboratory (NETL) is collaborating with other sponsors and the private sector to develop a Hybrid Program. This program will address the issues of technology development, integration, and ultimately the demonstration of what may be the most efficient of power plants in the world — the Hybrid System.

Analyses of several Hybrid concepts have indicated the potential of ultra-high efficiencies (approaching 80%). In the Hybrid, the synergism between the gas turbine and fuel cell provides higher efficiencies and lower costs than either system can alone.

Testing of the first Hybrid concept has been initiated at the National Fuel Cell Research Center (NFCRC).
Development of Dynamic Modeling Tools for Solid Oxide and Molten Carbonate Hybrid Fuel Cell Gas Turbine Systems
Authors: Gemmen Randall S. , Liese Eric , Rivera Jose G. , Jabbari Faryar , Brouwer Jacob
Published: August 2014

This paper describes some generic solid oxide and molten carbonate hybrid fuel cell gas turbine systems and dynamic modeling tools that are being developed to simulate the performance of these and other hybrid fuel cell systems. The generic hybrid systems are presented to introduce issues and technical development challenges that hybrid fuel cell gas turbine systems must address and to provide a platform for the development of the dynamic modeling tools. The present goals are to develop dynamic models for the basic components of solid oxide and molten carbonate fuel cell gas turbine hybrids, ensure their reliability, and obtain a basic understanding of their performance prior to integration into a complete hybrid system model. Preliminary results for molten carbonate and solid oxide fuel cell types are presented. These results provide understanding of some of the operational characteristics of fuel cells, and indicate the complexity of the dynamic response of fuel cell hybrid components. For the fuel cell models, generic planar designs are analyzed showing voltage and current behavior following step changes in load resistance and steady state performance curves. The results provide confidence in each of the model’s reliability, enabling them to be integrated for hybrid system simulation. Results from the integrated simulations will provide guidance on future hybrid technology development needs.
An International, Electronic and Interactive Teaching and Life-Long Learning Platform for Gas Turbine Technology in the 21st Century
Authors: Fransson Torsten H. , Hillion François-Xavier , Klein Eloi
Published: August 2014

An interactive learning platform which sets a new standard for electronic learning of gas turbine technology in a global life-long learning perspective is presented (Fig. 1). The platform contains a theoretical section in the form of several pages for each chapter available, with a significant number of related interactive simulations, movies, animations, virtual laboratory exercises, virtual study visits and realistic case studies. A significant background information related to historical development in the field, a display of existing components, nomenclature, multi-lingual dictionary and keywords, as well as questions for self-assessment and exams, an electronic communication group and a database of the user’s “successes and failures”, enhance the learning process in a significant way.

The program is intended as a platform for an international collaboration on learning heat and power technology. It can be used both in the classroom as well as for self-studies and is as such well adapted for both university and post-university learning, both on and off campus. Tools to facilitate the introduction of new material exist.

It is thus hoped that teachers at different universities can join forces and in a non-competitive way introduce material which can be shared, instead of developing similar simulations with somewhat different interfaces.

The long-term goal of the learning platform is of course that users world-wide will have the possibility to access the best teaching material available from any specialist, and that this material will contain supplementary pedagogical information which will enhance the learning both at a university and a post-university level.
Instructing the Principles of Gas Turbine Performance Monitoring and Diagnostics by Means of Interactive Computer Models
Authors: Mathioudakis K. , Stamatis A. , Tsalavoutas A. , Aretakis N.
Published: August 2014

The paper discusses how the principles employed for monitoring the performance of gas turbines in industrial duty can be explained by using suitable Gas Turbine performance models. A particular performance model that can be used for educational purposes is presented. The model allows the presentation of basic rules of gas turbine engine behavior and helps understanding different aspects of its operation. It is equipped with a graphics interface, so it can present engine operating point data in a number of different ways: operating line, operating points of the components, variation of particular quantities with operating conditions etc. Its novel feature, compared to existing simulation programs, is that it can be used for studying cases of faulty engine operation. Faults can be implanted into different engine components and their impact on engine performance studied. The notion of fault signatures on measured quantities is clearly demonstrated. On the other hand, the model has a diagnostic capability, allowing the introduction of measurement data from faulty engines and providing a diagnosis, namely a picture of how the performance of engine components has deviated from nominal condition, and how this information gives the possibility for fault identification.
U.S. Navy Rolls-Royce Allison 501-K34 Operating Experience
Authors: Russom Dennis M. , Jernoske Robert L.
Published: August 2014

The Rolls-Royce Allison (RRA) 501-K34 serves as the prime mover for the Ship Service Gas Turbine Generator sets (SSGTGs) of the U.S. Navy’s DDG-51 Class ships. Navy experience with the 501-K34 began in 1988 with the testing of the first prototype. Experience to date includes over 700,000 fired hours on a growing fleet of engines. This paper explores that operating experience and discusses future plans to improve the engine’s operational availability while lowering life cycle costs.
A Gas Turbine Engine Backup Bearing Operating Beyond 2.5 Million DN
Authors: Swanson Erik , Walton James F. , Heshmat Hooshang
Published: August 2014

Gas turbine engines and high speed rotating machinery using magnetic bearings require auxiliary and backup bearings for reliability and safety of operation. A 140 mm diameter Zero Clearance Auxiliary Bearing (ZCAB) capable of supporting radial and/or thrust loads of up to 4500 N was designed for an advanced gas turbine engine. The ZCAB was fabricated and tested successfully up to the expected maximum operating speed of 18,000 rpm in a specially configured test rig. The test rig included a 36,000 rpm capable drive motor, a 64 kg rotor which simulates a gas turbine engine shaft dynamics, a damped ball bearing at the drive end and an active magnetic bearing next to the ZCAB. Operation in excess of 240 minutes and 20 transient engagements simulating magnetic bearing failures were completed in the initial tests. Post test inspection revealed minimal wear to the shaft and the ZCAB rollers, whereupon the ZCAB was reassembled for shipment. These preliminary tests confirm the operation and durability of the ZCAB in maintaining rotor support and continued operation even if the primary magnetic bearing support is overloaded or encounters a failure.
Life Prediction for Complex Structures
Authors: Forth Scott C. , Annigeri Balkrishna S. , Keat William D.
Published: August 2014

The surface integral method, an indirect boundary element method that represents a crack as a distribution of force dipoles, has been developed to model 3D nonplanar crack growth in complex structures. The finite body was effectively modeled by superposition of stress influence functions for a half-space. As a result of this strategy, only the fracture has to be discretized. Crack propagation was modeled using the maximum circumferential stress theory to predict crack direction and the Forman fatigue equation, modified with an equivalent stress intensity solution for mixed-mode, to predict extension. Comparisons with benchmark solutions and field data verified the computational methodology and defined the limits of its applicability.
Rig and Engine Testing of Melt Infiltrated Ceramic Composites for Combustor and Shroud Applications
Authors: Corman Gregory S. , Dean Anthony J. , Brabetz Stephen , Brun Milivoj K. , Luthra Krishan L. , Tognarelli Leonardo , Pecchioli Mario
Published: August 2014

GE has developed SiC fiber reinforced SiC-Si matrix composites produced by silicon melt infiltration (MI) for use in gas turbine engine applications. High temperature, high pressure combustion rig testing and engine testing has been performed on combustor liners and turbine shrouds made from such MI composites. Frame 5 sized combustor liners were rig tested under LHE diffusion flame conditions for 150 hours, including 20 thermal trip cycles, with no observed damage to the ceramic liners. Similarly, 46 cm diameter, single piece turbine shroud rings were fabricated and tested in a PGT-2 gas turbine engine. The fabrication and testing of both components are described.
Modeling the Thermostructural Capability of Continuous Fiber-Reinforced Ceramic Composites
Authors: DiCarlo James A. , Yun Hee Mann
Published: August 2014

There exists today considerable interest in developing continuous fiber-reinforced ceramic matrix composites (CMC) that can operate as hot-section components in advanced gas turbine engines. The objective of this paper is to present simple analytical and empirical models for predicting the effects of time and temperature on CMC tensile rupture under various composite and engine conditions. These models are based on the average rupture behavior measured to air for oxide and SiC-based fibers of current technical interest. For example, assuming a cracked matrix and Larson-Miller rupture curves for single fibers, it is shown that model predictions agree quite well with high-temperature stress-rupture data for SiC/SiC CMC. Rupture models, yet to be validated, are also presented for three other relevant conditions: (a) SiC fibers become oxidatively bonded to each other in a cracked CMC, (b) applied CMC stresses are low enough to avoid matrix cracking, and (c) Si-based CMC are subjected to surface recession in high temperature combustion gases. The practical implications of the modeling results are discussed, particularly in regard to the optimum fibers and matrices for CMC engine applications and the thermostructural capability of SiC/SiC CMC in comparison to nickel-based superalloys, monolithic ceramics, and oxide/oxide CMC.
Experience With DLE Turbines at Offshore Installations
Authors: Carstensen Conrad , Skorping Roald
Published: August 2014

In this paper experience with some of the first gas turbines equipped with dry low NOx combustors installed in the North Sea is presented. The case history covers LM2500 and LM6000 gas turbines.

The paper outlines further some of the technical challenges for future applications in conformance with recent revisions of power plant air emission guidelines.
Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells
Authors: Kim Hyo-Joong , Seo Ki-Won , Kim Han-Ki , Noh Yong-Jin , Na Seok-In
Published: August 2014

The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10−5 Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10−3 Ω−1, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10 nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.
Sample-morphology effects on x-ray photoelectron peak intensities. II. Estimation of detection limits for thin-film materials
Authors: Powell Cedric J. , Werner Wolfgang S. M. , Smekal Werner
Published: August 2014

The authors show that the National Institute of Standards and Technology database for the simulation of electron spectra for surface analysis (SESSA) can be used to determine detection limits for thin-film materials such as a thin film on a substrate or buried at varying depths in another material for common x-ray photoelectron spectroscopy (XPS) measurement conditions. Illustrative simulations were made for a W film on or in a Ru matrix and for a Ru film on or in a W matrix. In the former case, the thickness of a W film at a given depth in the Ru matrix was varied so that the intensity of the W 4d5/2 peak was essentially the same as that for a homogeneous RuW0.001 alloy. Similarly, the thickness of a Ru film at a selected depth in the W matrix was varied so that the intensity of the Ru 3p3/2 peak matched that from a homogeneous WRu0.01 alloy. These film thicknesses correspond to the detection limits of each minor component for measurement conditions where the detection limits for a homogeneous sample varied between 0.1 at. % (for the RuW0.001 alloy) and 1 at. % (for the WRu0.01 alloy). SESSA can be similarly used to convert estimates of XPS detection limits for a minor species in a homogeneous solid to the corresponding XPS detection limits for that species as a thin film on or buried in the chosen solid.
VolHOG: A volumetric object recognition approach based on bivariate histograms of oriented gradients for vertebra detection in cervical spine MRI
Authors: Daenzer Stefan , Freitag Stefan , von Sachsen Sandra , Steinke Hanno , Groll Mathias , Meixensberger Jürgen , Leimert Mario
Published: August 2014

Purpose:

The automatic recognition of vertebrae in volumetric images is an important step toward automatic spinal diagnosis and therapy support systems. There are many applications such as the detection of pathologies and segmentation which would benefit from automatic initialization by the detection of vertebrae. One possible application is the initialization of local vertebral segmentation methods, eliminating the need for manual initialization by a human operator. Automating the initialization process would optimize the clinical workflow. However, automatic vertebra recognition in magnetic resonance (MR) images is a challenging task due to noise in images, pathological deformations of the spine, and image contrast variations.

Methods:

This work presents a fully automatic algorithm for 3D cervical vertebra detection in MR images. We propose a machine learning method for cervical vertebra detection based on new features combined with a linear support vector machine for classification. An algorithm for bivariate gradient orientation histogram generation from three‐dimensional raster image data is introduced which allows us to describe three‐dimensional objects using the authors' proposed bivariate histograms.

Results:

A detailed performance evaluation on 21 T2‐weighted MR images of the cervical vertebral region is given. A single model for cervical vertebrae C3–C7 is generated and evaluated. The results show that the generic model performs equally well for each of the cervical vertebrae C3–C7. The algorithm's performance is also evaluated on images containing various levels of artificial noise. The results indicate that the proposed algorithm achieves good results despite the presence of severe image noise.

Conclusions:

The proposed detection method delivers accurate locations of cervical vertebrae in MR images which can be used in diagnosis and therapy. In order to achieve absolute comparability with the results of future work, the authors are following an open data approach by making the image dataset used in their performance evaluation available to the public.
Encyclopaedia of Medical Physics (2 volumes).
Authors: Driewer Joseph
Published: August 2014

Encyclopaedia of Medical Physics (2 volumes). S. Tabakov F. Milano S.‐E. Strand C. Lewis P. Sprawls CRC Press, Taylor & Francis Group, Boca Raton, FL, 2013. Hardcover 908. pp. Price: $755.00. ISBN: 978‐1439846520
Metatarsophalangeal Joint Function During Sprinting: A Comparison of Barefoot and Sprint Spike Shod Foot Conditions
Authors: Smith Grace , Lake Mark , Lees Adrian
Published: August 2014

The metatarsophalangeal joint is an important contributor to lower limb energetics during sprint running. This study compared the kinematics, kinetics and energetics of the metatarsophalangeal joint during sprinting barefoot and wearing standardized sprint spikes. The aim of this investigation was to determine whether standard sprinting footwear alters the natural motion and function of the metatarsophalangeal joint exhibited during barefoot sprint running. Eight trained sprinters performed maximal sprints along a runway, four sprints in each condition. Three-dimensional high-speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Joint angle, angular velocity, moment, power and energy were calculated for the metatarsophalangeal joint. Sprint spikes significantly increase sprinting velocity (0.3 m/s average increase), yet limit the range of motion about the metatarsophalangeal joint (17.9% average reduction) and reduce peak dorsiflexion velocity (25.5% average reduction), thus exhibiting a controlling affect over the natural behavior of the foot. However, sprint spikes improve metatarsophalangeal joint kinetics by significantly increasing the peak metatarsophalangeal joint moment (15% average increase) and total energy generated during the important push-off phase (0.5 J to 1.4 J). The results demonstrate substantial changes in metatarsophalangeal function and potential improvements in performance-related parameters due to footwear.
Using a Discrete Preisach Model for Hysteresis in Ankle Joint Passive Moment
Authors: Chan Ching-Chao , Lin Chou-Ching K. , Ju Ming-Shaung
Published: August 2014

The steady-state passive joint moment was considered as a nonlinear elasticity in the past. However, we found that it was path dependent and the estimation error could be large if the commonly used path-independent functions were adopted. The aim of this study was to develop a model to describe the movement history-dependent passive moment in the steady state. The steady-state passive ankle moments of the rabbit were measured by a series of ramp-and-hold angle changes (stairway angle trajectory). A customized discrete Preisach model was constructed and a commonly adopted double-exponential function was also implemented. Two sets of data with different angle paths (major loop and inward loop trajectories) were acquired for model validation. The performance of the two models was compared. The results showed that the proposed model could accurately estimate the steady-state passive moment for both sets of validation data. The estimated error of the proposed model was approximately 50% smaller than that of the double-exponential function approach. It is expected that this new approach, by reducing the error of estimating passive joint moment, may contribute to the active control of joint moments.
A service-level action research intervention to improve identification and treatment of cannabis and related mental health issues in young Indigenous Australians: a study protocol
Authors: Bohanna India , Bird Katrina , Copeland Jan , Roberts Nicholas , Clough Alan
Published: August 2014

Introduction

Regular cannabis use is associated with negative mental health impacts including psychosis, depression and anxiety. Rates of cannabis use have increased in Aboriginal and Torres Strait Islander communities in northern Australia within the last two decades, presenting a significant increased risk to young people's mental health in these regions. Improved screening, early detection and treatment for cannabis-related mental health issues are urgently required. This paper describes a service-level action research intervention and evaluation protocol for use in the few services where it is possible to engage young Aboriginal and Torres Strait Islander Australians.

Methods/Design

The protocol is being developed in two services where youth mental health is core business: a primary healthcare centre and a youth service in the Cairns and hinterland region, far north Queensland. The protocol calls first for baseline data to be collected using staff and client surveys; network mapping; and analysis of screening, treatment and referral rates. The protocol's intervention phase is driven by service needs identified from baseline data. Intervention strategies focus on implementing/enhancing cannabis screening instruments and processes in line with current best practice; enhancing networks with external drug and mental health services; developing culturally acceptable training and resources; developing activities aiming to reduce cannabis use in young Aboriginal and Torres Strait Islander clients using the services. The protocol requires implementation of the multilevel intervention within each service for 1 year, with follow-up data then collected and compared to baseline. Process evaluation identifies the more effective intervention strategies and documents the challenges to be overcome for full implementation.

Ethics and dissemination

Ethics approval was provided by The James Cook University, Human Research Ethics Committee. Ethics Approval Number H5322. Peer-reviewed publications will also be used to disseminate the finding. Results will also be discussed with stakeholder organisations.
Gene conversions are frequent but not under positive selection in the Siglec gene families of primates
Authors: Zid Mouldi , Drouin Guy
Published: August 2014

Siglecs are cell surface proteins that belong to the immunoglobulin superfamily and which bind sialic acids. They are composed of two groups, the conserved Siglecs and the CD33-related Siglecs. Previous studies have reported the occurrence of gene conversions between human CD33-related Siglecs and suggested that these conversions are adaptive because they increase the diversity of these immunoglobulin-related genes. Here, we analyze the Siglec genes of five primate species and show that gene conversions are not observed between conserved Siglec genes but that they are frequent between primate CD33-related Siglecs. The gene conversions between CD33-related Siglec genes only occur between similar genes and equally frequently in sialic acid binding and nonbinding domains. Furthermore, dN/dS ratio tests show that most of the Ig-like V-type 1 and the Ig-like C2-type 1 domains of Siglec genes evolve either neutrally or under purifying selection and that gene conversions were not responsible for the positively selected regions detected in the Ig-like V-type1 domain of the human SIGLEC7 and SIGLEC9 genes. Our results suggest that the frequent gene conversions between CD33-related Siglec genes are simply a consequence of the high degree of sequence similarity of these genes and that they are not adaptive.
Dynamic Instability Characteristics of Thin Plate Like Beam with Internal Damage Subjected to Follower Load
Authors: Karthick Subramani , Datta Prosun Kumar
Published: August 2014

This study investigates the vibration, buckling and dynamic instability characteristics of damaged cross-ply and angle-ply laminated plate like beam under follower loading using the finite element approach. The damage is anisotropic in nature and parametrically incorporated into the composite using the concept of reduction in stiffness. It has been observed that damage shows a strong orthogonality and in general deteriorates the vibration and buckling characteristics. For follower type of loading, analysis is carried out on plate like beam structure to obtain the flutter characteristics. The effects of damage and its location on flutter characteristics are studied. The desirable position of damage on the plate like beam structure based on different stability behavior is discussed. The results show that flutter is observed as primary modes of instability when damaged plate like beam is subjected to follower loads. The behavior of flutter characteristics for different damaged parameters is discussed.
Adaptive Speculative Processing of Out-of-Order Event Streams
Authors: Mutschler Christopher , Philippsen Michael
Published: August 2014

Distributed event-based systems are used to detect meaningful events with low latency in high data-rate event streams that occur in surveillance, sports, finances, etc. However, both known approaches to dealing with the predominant out-of-order event arrival at the distributed detectors have their shortcomings: buffering approaches introduce latencies for event ordering, and stream revision approaches may result in system overloads due to unbounded retraction cascades.

This article presents an adaptive speculative processing technique for out-of-order event streams that enhances typical buffering approaches. In contrast to other stream revision approaches developed so far, our novel technique encapsulates the event detector, uses the buffering technique to delay events but also speculatively processes a portion of it, and adapts the degree of speculation at runtime to fit the available system resources so that detection latency becomes minimal.

Our technique outperforms known approaches on both synthetical data and real sensor data from a realtime locating system (RTLS) with several thousands of out-of-order sensor events per second. Speculative buffering exploits system resources and reduces latency by 40% on average.
MCEP
Authors: Ottenwälder Beate , Koldehofe Boris , Rothermel Kurt , Hong Kirak , Lillethun David , Ramachandran Umakishore
Published: August 2014

With the proliferation of mobile devices and sensors, complex event proceesing (CEP) is becoming increasingly important to scalably detect situations in real time. Current CEP systems are not capable of dealing efficiently with highly dynamic mobile consumers whose interests change with their location. We introduce the distributed mobile CEP (MCEP) system which automatically adapts the processing of events according to a consumer's location. MCEP significantly reduces latency, network utilization, and processing overhead by providing on-demand and opportunistic adaptation algorithms to dynamically assign event streams and computing resources to operators of the MCEP system.
The CREB-Binding Protein Inhibitor ICG-001 Suppresses Pancreatic Cancer Growth
Authors: Arensman Michael D. , Telesca Donatello , Lay Anna R. , Kershaw Kathleen M. , Wu Nanping , Donahue Timothy R. , Dawson David W.
Published: August 2014

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer due in part to a lack of highly robust cytotoxic or molecular-based therapies. Recent studies investigating ligand-mediated Wnt/β-catenin signaling have highlighted its importance in pancreatic cancer initiation and progression, as well as its potential as a therapeutic target in PDAC. The small-molecule ICG-001 binds cAMP-responsive element binding (CREB)-binding protein (CBP) to disrupt its interaction with β-catenin and inhibit CBP function as a coactivator of Wnt/β-catenin–mediated transcription. Given its ability to inhibit Wnt/β-catenin–mediated transcription in vitro and in vivo, as well as its efficacy in preclinical models of colorectal cancer and other Wnt-driven diseases, we examined ICG-001 and its potential role as a therapeutic in PDAC. ICG-001 alone significantly inhibited anchorage-dependent and -independent growth of multiple PDAC lines, and augmented in vitro growth inhibition when used in combination with gemcitabine. ICG-001 had only variable modest effects on PDAC apoptosis and instead mediated PDAC growth inhibition primarily through robust induction of G1 cell-cycle arrest. These effects, however, seemed decoupled from its inhibition of Wnt/β-catenin–mediated transcription. DNA microarrays performed on PDAC cells in the context of ICG-001 treatment revealed ICG-001 altered the expression of several genes with well-established roles in DNA replication and cell-cycle progression, including direct actions on SKP2 and CDKN1A. ICG-001 also significantly prolonged survival in an in vivo orthotopic xenograft model of PDAC, indicating ICG-001 or derived compounds that disrupt CBP activity are potentially useful small-molecule therapeutics for pancreatic cancer. Mol Cancer Ther; 13(10); 2303–14. ©2014 AACR.