bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary Design of a Double Expansion Through Flow Wave Rotor: Thermal and Gas Dynamic Analysis
Authors: Materano Gilberto , Savill Mark
Published: November 2013

The wave rotor is a device capable of increasing the pressure of a fluid by deploying shock waves in a transient process. The operation principle is based on the shock tube where shock waves, rarefaction waves and contact waves result from the mixture of fluids with different levels of total pressure. The incorporation of a wave rotor into a gas turbine increases the machine thermal efficiency and reduces fuel consumption, thus allowing the development of new environmentally friendly technologies. The preliminary design of a wave rotor can be achieved by following two fundamental steps. Firstly, it is necessary to carry out a thermal analysis of the cycle in order to obtain the fluid state at each port of the device, secondly to track the different waves generated during the process in order to determine the dimensionality of the wave rotor. The thermal analysis can be accomplished if the performance of the wave rotor is predicted in advance, to set the trajectory of the cycle. The performance prediction can be obtained from the analytical solution of the one-dimensional equations used to describe compressible flow, in a gas dynamic evaluation. Among the available alternatives to perform the gas dynamic analysis, this work considers the algorithm of Weber, because it has proven to be robust by ensuring the mass balance across all the device ports, and also as this technique has not been used previously to evaluate the performance of propulsion gas turbines. In this study, four thermal cycles of gas turbine with a double expansion through-flow wave rotor were considered. These configurations come from changes of some processes in the thermal cycle to a turbofan implemented in business jets, which is set as the baseline engine. In each cycle the wave rotor is exposed to different velocities, expressed as Mach numbers, of the injected air that comes from the compressor, as well as different temperature ratios between this air and the gases that come from the combustion chamber in order to evaluate changes in the overall efficiency of the cycle and the specific thrust. The results obtained from this study show that not all the possible cases can be implemented in propulsion gas turbines, and none of the cases that prove to be suitable has a single point of operation. Rather they have a range of operations with maximum specific thrust and minimum specific fuel consumption, located at different operation conditions.
A New Loss and Deviation Model for Axial Compressor Inlet Guide Vanes
Authors: Banjac Milan , Petrovic Milan V. , Wiedermann Alexander
Published: November 2013

This paper describes a new universal algebraic model for the estimation of flow deflection and losses in axial compressor inlet guide vane devices. The model deals with nominal flow and far-off-design operating conditions in connection with large stagger angle adjustments. The first part of the model considers deflection and losses in 2D cascades, taking into account the main cascade geometry parameters and operating conditions, such as Mach number and stagger adjustment. The second part of the model deals with additional deviation and losses due to secondary flow caused by the endwall viscous effects and by the trailing vortices. The model is developed for NACA65 airfoils, NACA63-A4K6 airfoils and airfoils having an NACA65 thickness distribution on a circular-arc camber line. It is suitable for application in 1D or 2D through-flow calculations for design and analysis cases. The development of the method is based on systematic CFD flow calculations for various cascade geometries and operating parameters. The comparison of correlation results with experimental data for several test cases shows good agreement.
Evaluation of RANS Transition Modeling for High Lift LPT Flows at Low Reynolds Number
Authors: Keadle Kevin , McQuilling Mark
Published: November 2013

High lift low pressure turbine airfoils have complex flow features that can require advanced modeling capabilities for accurate flow predictions. These features include separated flows and the transition from laminar to turbulent boundary layers. Recent applications of computational fluid dynamics based on the Reynolds-averaged Navier-Stokes formulation have included modeling for attached and separated flow transition mechanisms in the form of empirical correlations and two- or three-equation eddy viscosity models. This study uses the three-equation model of Walters and Cokljat [1] to simulate the flow around the Pack B and L2F low pressure turbine airfoils in a two-dimensional cascade arrangement at a Reynolds number of 25,000. This model includes a third equation for the development of pre-transitional laminar kinetic energy (LKE), and is an updated version of the Walters and Leylek [2] model. The aft-loaded Pack B has a nominal Zweifel loading coefficient of 1.13, and the front-loaded L2F has a nominal loading coefficient of 1.59. Results show the updated LKE model improves predicted accuracy of pressure coefficient and velocity profiles over its previous version as well as two-equation RANS models developed for separated and transitional flows. Transition onset behavior also compares favorably with experiment. However, the current model is not found suitable for wake total pressure loss predictions in two-dimensional simulations at extremely low Reynolds numbers due to the predicted coherency of suction side vortices generated in the separated shear layers which cause a local gain in wake total pressure.
Novel Gas Turbine Exhaust Temperature Measurement System
Authors: DeSilva Upul , Bunce Richard H. , Claussen Heiko
Published: November 2013

Siemens Energy, Inc. has been investigating the potential of a new approach to measuring the process gas temperature leaving the turbine of their heavy industrial gas turbine engines using an acoustic pyrometer system. This system measures the bulk temperature crossing a plane behinds the last row of turbine blades and is a non-intrusive measurement. It has the potential to replace the current intrusive multiple point measurement sensor arrays for both engine control and performance evaluation. The acoustic pyrometer is a device that measures the transit time of an acoustic pulse across the exhaust duct of the engine. An estimate of the temperature of the process fluid can be made from the transit time. Multiple passes may be made at various radial positions to improve the measurement. The gas turbine exhaust is a challenging environment for acoustic temperature measurement where there can be significant temperature stratification and high velocity. Previous applications of acoustic pyrometers to measure process gas temperature in power plants have been confined to applications such as boilers where rapid temperature changes are not expected and fluid velocity patterns are well known. The present study describes the results of acoustic pyrometer testing in an operating gas turbine engine under load using an active acoustic pyrometer system containing eight sets of transmitters and receivers, all external to the turbine exhaust flow path. This active method technology is based on the temperature dependence of the isentropic speed of sound from the simple ideal gas assumptions. Sound transmitters and receivers are mounted around the exhaust duct to measure the speed of sound. Very sophisticated topographical mapping techniques have been developed to extract temperature distribution from using any where from 2 to 8 sensors with up to 24 paths and 400 points. Cross correlation of sensor results to obtain topographical mapping of gas isotherms in a plane in full engine field tests have been conducted to prove the feasible of this technology on a gas turbine engine. The initial installation of the active acoustic pyrometer system in an engine exhaust was accomplished in 2009. All the tests indicate that the steady state measurements of the acoustic pyrometer system fall within 10C of the measured exhaust thermocouple data. An additional installation on a different model engine was subsequently made and data have been gathered and analyzed. Results of these tests are presented and future evaluation options discussed.
Numerical Prediction of NOx Emission and Exit Temperature Pattern in a Model Staged Lean Premixed Prevaporized Combustor
Authors: Zhang Man , Wu Hao , Wang Hao
Published: November 2013

Steady-state Reynolds Averaged Navier-Stokes (RANS) equations are solved in the present numerical investigation to simulate the reactive two-phase flow in a model aero-engine combustor, and the reactive flow field with NOx emissions is analyzed. The gaseous phase is modeled by the modified SST turbulence model, and the liquid phase is modeled by Lagrangian tracking method considering the droplet breakup, collision and evaporation. Turbulence-combustion interaction is modeled by the extended coherent flame model, and NOx emissions are modeled by solving the species transport equation based on the assumption of frozen temperature. The fuel system of the present simulated combustor is radially staged, with a main stage employing the principle of lean prevaporized and premixed (LPP) concept to reduce pollutant emission, and a pilot stage burning a diffusion flame for flame stability. For the exit temperature quality improvement, dilution air is assigned with little amount of airflow. Detailed numerical results including exit temperature distribution, dominant burning performances and species distributions are evaluated for the combustion with and without dilution air. The influence of upstream burning characteristics to downstream temperature distribution is assessed. Numerical prediction of NOx emission demonstrates its capability of a reasonable reduction, and the exit temperature pattern with the dilution air is also able to fulfill its design target.
Siemens SGT-800 Industrial Gas Turbine Enhanced to 50 MW: Turbine Design Modifications, Validation and Operation Experience
Authors: Wang Lieke , Bahador Mehdi , Bruneflod Simon , Annerfeldt Mats , Björkman Mats , Hultmark Ingvar
Published: November 2013

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5 MW with a 38.3 % electrical efficiency (ISO) in simple cycle and the best in class combined-cycle performance of more than 55 %. The increased power and improved efficiency from the existing 47 MW rating are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The upgrade components in the gas turbine are interchangeable from the existing rating. The current paper is focused on the design modifications of the turbine parts and their validation and operation experience.

For the turbine section, the main design modifications include the redesigned stage 1 with better aerodynamic and cooling performance, modified stage 3 for increased outlet area, etc. However, the turbine inlet temperature is not increased compared to the existing 47 MW rating. Comprehensive validation measures have been taken to make sure that the modifications meet the design targets, at both the component level and the system level. The results from the validation tests have confirmed the turbine performance in terms of aerodynamics, cooling, life time, etc. In addition, these results have given a strong basis for future upgrade, e.g., potential cooling air saving has been identified on several areas. The first SGT-800 with 50.5 MW rating was successfully operated and tested during the spring 2010 and the expected performance figures were confirmed. Up to January 2013, the fleet of this new rating has accumulated >40 000 Equivalent Operation hours (EOH), while the fleet leader has accumulated >16 000 EOH. A planned follow up inspection was made after 10 000 EOH by using borescope for the hot section, and it showed that all the turbine parts were in good condition.
Reduced-Order Through-Flow Design Code for Highly Loaded, Cooled Axial Turbines
Authors: Sammak Majed , Thern Marcus , Genrup Magnus
Published: November 2013

The development of advanced computational fluid dynamic codes for turbine design does not substitute the importance of mean-line codes. Turbine design involves mean-line design, through-flow design, airfoil design, and finally 3D viscous modeling. The preliminary mean-line design continues to play an important role in early design stages. The aim of this paper was to present the methodology of mean-line designing of axial turbines and to discuss the computational methods and procedures used. The paper presents the Lund University Axial Turbine mean-line code (LUAX-T). LUAX-T is a reduced-order through-flow tool that is capable of designing highly loaded, cooled axial turbines. The stage computation consists of three iteration loops — cooling, entropy, and geometry iteration loop. The stage convergence method depends on whether the stage is part of the compressor turbine (CT) or power turbine (PT) stages, final CT stage, or final PT stage. LUAX-T was developed to design axial single- and twin-shaft turbines, and various working fluid and fuel compositions can be specified. LUAX-T uses the modified Ainley and Mathieson loss model, with the cooling computation based on the m*-model. Turbine geometries were established by applying various geometry correlations and methods. The validation was performed against a test turbine that was part of a European turbine development program. LUAX-T validated the axial PT of the test turbine, which consisted of two stages with rotational speed 13000 rpm. LUAX-T showed good agreement with the available performance data on the test turbine. The paper presented also the mean-line design of an axial cooled twin-shaft turbine. Design parameters were kept within limits of current practice. The total turbine power was 109 MW, of which the CT power was 55 MW. The CT was designed with two stages with a rotational speed of 9500 rpm, while the PT had two stages with a rotational speed of 6200 rpm. The total cooling mass flow was calculated to 31 kg/s, which corresponds to 23 % of compressor inlet mass flow. LUAX-T proved capable of designing uncooled and cooled turbines.
Actively Lubricated Bearings Applied as Calibrated Shakers to Aid Parameter Identification in Rotordynamics
Authors: Santos Ilmar Ferreira , Varela Alejandro Cerda
Published: November 2013

The servo valve input signal and the radial injection pressure are the two main parameters responsible for dynamically modifying the journal oil film pressure and generating active fluid film forces in controllable fluid film bearings. Such fluid film forces, resulting from a strong coupling between hydrodynamic, hydrostatic and controllable lubrication regimes, can be used either to control or to excite rotor lateral vibrations. An accurate characterization of the active oil film forces is of fundamental importance to elucidate the feasibility of applying the active lubrication as non-invasive perturbation forces, or in other words, as a “calibrated shaker”, to perform in-situ rotordynamic tests. The main original contributions of this paper are three: a) the experimental characterization of the active fluid film forces generated in an actively-lubricated tilting-pad journal bearing in the frequency domain and the application of such a controllable bearing as a calibrated shaker aiming at determining the frequency response function (FRF) of rotordynamic systems; b) experimental quantification of the influence of the supply pressure and servo valve input signal on the FRF of rotor-journal bearing systems; c) experimental indication of how small such active fluid film forces (perturbation forces) should be, in order to perturb the rotor-journal bearing system without significantly changing its dynamic characteristics. To validate the experimental procedure and results obtained via actively-lubricated bearing, similar experimental tests are carried out using an electro-magnetic shaker. Very good agreements between the two experimental approaches are found. Maximum values of the main input parameters, namely servo valve voltage and radial injection pressure, are experimentally identified/suggested with the objective of obtaining non-invasive perturbation forces.
Investigation of Alternate Mistuned Turbine Blades Non-Linear Coupled by Underplatform Dampers
Authors: Tatzko S. , Panning-von Scheidt L. , Wallaschek J. , Kayser A. , Walz G.
Published: November 2013

Freestanding turbine blades have typically low structural damping and thus require additional friction damping devices, such as underplatform dampers. The friction coupling between neighboring blades reduces response amplitude and increases resonance frequency. Along with forced response excitation large blades, especially of last stage, could be excited by fluid structural interaction (flutter). To prevent such excitation alternate mistuned blade patterns are beneficial disturbing traveling waves in the stage.

In this paper the influence of alternate mistuning is investigated with a simplified oscillator chain as well as a bladed disk assembly coupled by frictional contacts. It is pointed out that the performance of friction coupling can be improved by alternate mistuning as long as the engine order of the excitation is below quarter of the number of blades. Alternate mistuning causes a mode coupling between two nodal diameter vibration mode shapes allowing for energy transfer. The in-house developed software code DATAR is enhanced and alternate mistuning can be applied to the blades as well as to the damping elements. For validation the DATAR code was applied to an alternate mistuned last stage blade of a Siemens gas turbine and compared with available field engine measurement.
Structural Change Quantification in Rotor Systems Based on Measured Resonance and Antiresonance Frequencies
Authors: Wroblewski Adam C. , Pesch Alexander H. , Sawicki Jerzy T.
Published: November 2013

A structural change quantification methodology is proposed in which the magnitude and location of a structural alteration is identified experimentally in a rotor system. The resonance and antiresonance frequencies are captured from multiple frequency response functions and are compared with baseline data to extract frequency shifts due to these features. The resulting expression contains sufficient information to identify the dynamic characteristics of the rotor in both the frequency and spatial domains. A finite element model with carefully selected tunable parameters is iteratively adjusted using a numerical optimization algorithm to determine the source of the structural change. The methodology is experimentally demonstrated on a test rig with a laterally damaged rotor and the frequency response functions are acquired through utilization of magnetic actuators positioned near the ball bearings.
Finite-Element Modelling of an Experimental Mistuned Bladed Disk and Experimental Validation
Authors: de Cazenove Jean , Cogan Scott , Mbaye Moustapha
Published: November 2013

Integrally bladed rotors dynamic properties are known to be particularly sensitive to small geometric discrepancies due to the machining process or in-service wear. In this context, it is straightforward that setting up accurate numerical models which take into account real mistuning patterns is a key issue in the prediction of forced response amplitudes under operating conditions. The present study focuses on an experimental bladed disk. Due to strong inter-blade coupling, the geometric mistuning is supposed to result in severe mode localization for the studied bladed disk, thus emphasizing the need of a realistic, predictive finite-element model. This paper describes the procedure which leads to the development and validation of a high-fidelity FE model for a realistic bladed disk, based on coordinate measurements by means of fringe projection. After giving an overview of the coordinate measurement and model building for the studied bladed disk, the comparison of cantilevered-blade and full disk calculated eigenfrequencies to individual blade and full disk in quasi-vacuum measurements are presented.
Improvement of Compressor Blade Vibrations Spectral Analysis From Tip Timing Data: Aliasing Reduction
Authors: Vercoutter A. , Lardies J. , Berthillier M. , Talon A. , Burgardt B.
Published: November 2013

Tip-timing is a technique for measuring rotating blades vibrations in operation. Its concept exists since the early 70s but it has been more experimented in the last decade through improvements in hardware and software capabilities. It consists of a set of sensors mounted on stator casings that record blade passing times. Then, from this measurement, blade vibrations can be estimated.

Tip-timing technique presents several advantages compared to usual mean of measurement: strain gages. Indeed, installation is easier, it is non-intrusive and all the blades can be monitored.

However, resulting sampling depends on physical configuration i.e. number of sensors. In practice, as the number of sensors is limited, sampling rate is low in relation to the physical observed frequencies and do not respect the Shannon criterion. Thus, it generates important aliasing effects in spectrum, which makes the analysis difficult. In fact, such measurements aim to lead to pseudo-blind analysis, especially for asynchronous vibrations, when there is no hypothesis of underneath structural model.

This main problem of aliasing is partially softened by using a minimum variance spectral estimator that iteratively reduces non-physical content in spectrum, but pseudo-blind analysis remains complicated.

This paper presents a comparison of several methods based on different multisampling averaging concepts for reducing aliasing. Multisampling averaging consists in averaging spectrums from different sampling patterns of the same original signal, so that only stable physical content remains in the final spectrum. This study is presented on different industrial test cases of blade vibrations.
Polymer-Derived Ceramic Sensors for Temperature Measurement in Harsh Environment
Authors: Freese Douglas , Shao Gang , Xu Chengying
Published: November 2013

Development of an ultra-high temperature sensor advocates numerous applications in a variety of diverse fields. Combustion turbine engine advancements are predominately the benefactors of high temperature measurement capabilities; founded upon the principle of higher combustion reaction efficiency. The interior combustion chamber of a gas turbine is an extremely hostile environment for any typical material, especially a measurement component. Implementing the conductive properties and high temperature stability of a polymer derived ceramic (PDC) offers a solution to this predicament. Complementing the virtuous mechanical properties of the unique ceramic is micro-machinability and tunable electric characteristics established from the precursor compounds. The thermo-electric qualities of the PDC prepare formulation of a relationship between the changing temperatures of the research environment with respect to the internal resistance of the ceramic. An elected measurement system will actively monitor a PDC sensory circuit as well as reference thermocouple temperature. Series of response experiments were performed to characterize the functionality of the sensor within the high temperature environment.
Template‐based automatic breast segmentation on MRI by excluding the chest region
Authors: Lin Muqing , Chen Jeon‐Hor , Wang Xiaoyong , Chan Siwa , Chen Siping , Su Min‐Ying
Published: November 2013

Purpose:

Methods for quantification of breast density on MRI using semiautomatic approaches are commonly used. In this study, the authors report on a fully automatic chest template‐based method.

Methods:

Nonfat‐suppressed breast MR images from 31 healthy women were analyzed. Among them, one case was randomly selected and used as the template, and the remaining 30 cases were used for testing. Unlike most model‐based breast segmentation methods that use the breast region as the template, the chest body region on a middle slice was used as the template. Within the chest template, three body landmarks (thoracic spine and bilateral boundary of the pectoral muscle) were identified for performing the initial V‐shape cut to determine the posterior lateral boundary of the breast. The chest template was mapped to each subjectˈs image space to obtain a subject‐specific chest model for exclusion. On the remaining image, the chest wall muscle was identified and excluded to obtain clean breast segmentation. The chest and muscle boundaries determined on the middle slice were used as the reference for the segmentation of adjacent slices, and the process continued superiorly and inferiorly until all 3D slices were segmented. The segmentation results were evaluated by an experienced radiologist to mark voxels that were wrongly included or excluded for error analysis.

Results:

The breast volumes measured by the proposed algorithm were very close to the radiologistˈs corrected volumes, showing a % difference ranging from 0.01% to 3.04% in 30 tested subjects with a mean of 0.86% ± 0.72%. The total error was calculated by adding the inclusion and the exclusion errors (so they did not cancel each other out), which ranged from 0.05% to 6.75% with a mean of 3.05% ± 1.93%. The fibroglandular tissue segmented within the breast region determined by the algorithm and the radiologist were also very close, showing a % difference ranging from 0.02% to 2.52% with a mean of 1.03% ± 1.03%. The total error by adding the inclusion and exclusion errors ranged from 0.16% to 11.8%, with a mean of 2.89% ± 2.55%.

Conclusions:

The automatic chest template‐based breast MRI segmentation method worked well for cases with different body and breast shapes and different density patterns. Compared to the radiologist‐established truth, the mean difference in segmented breast volume was approximately 1%, and the total error by considering the additive inclusion and exclusion errors was approximately 3%. This method may provide a reliable tool for MRI‐based segmentation of breast density.
Inter‐slice bidirectional registration‐based segmentation of the prostate gland in MR and CT image sequences
Authors: Khalvati Farzad , Salmanpour Aryan , Rahnamayan Shahryar , Rodrigues George , Tizhoosh Hamid R.
Published: November 2013

Purpose:

Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2‐weighted MR and CT image sequences.

Methods:

The proposedInter‐Slice Bidirectional Registration‐based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques).

Results:

The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland.

Conclusions:

The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability.
Improving oral function and cosmesis in a case of Freeman-Sheldon syndrome
Authors: Vyas Vishal , Agha Riaz , Ahmad Tariq
Published: November 2013

Children born with the rare congenital condition Freeman-Sheldon syndrome (FSS) have a characteristic facial appearance: microstomia, a long philtrum, ‘H-shaped’ chin abnormality and ‘pinched lips’ in addition to extra-facial features such as kyphoscoliosis and hand deformities. Such children often have problems with oral continence and difficulties with speech leading to both nutritional and psychosocial concerns. Prompt correction through surgery is therefore important in effectively managing the condition. We report the case of a 7-year-old girl who presented with the appearance of scarred lips with difficulties in closing her mouth, a speech impediment and oral incontinence. Using a muscle-sparing technique to reconstruct the upper and lower lips, better oral continence was achieved alongside markedly improved speech and an aesthetically pleasing result. Taken together, this case aptly illustrates the benefits of lip reconstruction in improving function and cosmesis in patients with FSS.
A patient with pneumopericardium secondary to extranodal T-cell lymphoma
Authors: Sener Yusuf Ziya , Babacan Taner , Sarıca Mehmet Akif , Turkbeyler Ibrahim Halil
Published: November 2013

Natural killer (NK)/T-cell lymphomas represent a rare type of lymphoma derived from either activated NK cells or cytotoxic T cells. Most cases with T/NK cell lymphoma present with extranodal manifestations. Primary nodal disease is very rare. The upper respiratory tract is the most common site involved in extranodal disease. Symptoms include epistaxis and nasal obstruction. T/NK cell lymphomas show aggressive and invasive clinical progression, with a poor prognosis. Without treatment, survival is measured in months. We report a case of a 51-year-old male patient with pneumopericardium as a complication of intestinal T/NK cell lymphoma. To the best of our knowledge, this is the first report showing pneumopericardium as a fatal complication of T/NK cell lymphoma. Pneumopericardium should be considered in patients diagnosed with T/NK cell lymphoma presenting with chest pain.
Warm mix asphalt by water-containing methodology: a laboratory study on workability properties versus micro-foaming time
Authors: Vaiana Rosolino , Iuele Teresa , Gallelli Vincenzo , Tighe Susan L.
Published: November 2013

This paper focuses on a laboratory investigation of compaction characteristics of warm mix asphalt produced with the addition of synthetic zeolites. The influence of the time elapsed between mixing and compaction operations on mix compactibility was evaluated to define an optimum “micro-foaming time” (MFT), in which the additive can completely release the water contained. A comparison between traditional hot mix asphalt and warm mixes was carried out; two compaction methods (impact and gyratory) were used. Mix compactibility was firstly evaluated in terms of air voids content for each condition of compaction (immediately after mixing or after 1–2 h of storage in an oven). Mix resistance to densification and to distortion was investigated by means of compaction indexes and traffic indexes. Data showed that the foaming process due to the addition of the zeolite has a peak value of intensity after 1 h of MFT. This effect seems to vanish after a longer period of time. Outcomes of this study are expected to benefit both practitioners and researchers.
Paleomagnetic dating of magmatic phases at the Cantung tungsten deposit, Northwest Territories, Canada
Authors: Kawasaki K. , Symons D.T.A.
Published: November 2013

The Cantung tungsten–copper (W–Cu) skarn orebodies are hosted by Proterozoic and Lower Cambrian metasedimentary rocks next to the Cretaceous “Mine Stock” monzogranite. Paleomagnetic analyses of 283 specimens from the Open Pit scheelite–chalcopyrite orebody (17 sites) and from adjacent host rocks including the aplite dikes (11 sites) isolated a stable characteristic remanent magnetization (ChRM), mostly by alternating field and then thermal step demagnetization. The step demagnetization results along with rock magnetic analyses of the W concentrate show that the main remanence carriers are single- or pseudosingle-domain pyrrhotite, titanomagnetite, and (or) magnetite. There is no statistically significant difference at 95% confidence between the site mean ChRM directions for the W–Cu ore, the host rock, or the aplite dikes populations. This result indicates that the intrusion of the Mine Stock is coeval with the genesis of the scheelite skarn ore and with dike emplacement to give an overall mean ChRM direction of declination 342.9°, inclination 82.0° (N = 22 sites, radius of cone of 95% confidence α95 = 4.2°, precision parameter k = 54.7) that defines a paleopole at 76.2°N latitude, 212.2°E longitude (radius of cone of 95% confidence A95 = 8.1°). This paleopole is concordant with the coeval 98 Ma North American paleopole at 92% confidence, which provides strong evidence that the eastern Selwyn Basin has been an autochthonous part of North America since the mid-Cretaceous.
(0, 2) CHIRAL LIOUVILLE FIELD THEORY
Authors: NAKAYAMA YU
Published: November 2013

As an existence proof of the (0, 2) heterotic supercurrent supermultiplets in (1+1)-dimensional quantum field theories which are consistent with the warped superconformal algebra, we construct the (0, 2) chiral Liouville field theories. The two distinct possibilities of the heterotic supercurrent supermultiplets are both realized.
SUPERSONIC FLUTTER CONTROL OF AN ELECTRORHEOLOGICAL FLUID-BASED SMART CIRCULAR CYLINDRICAL SHELL
Authors: HASHEMINEJAD SEYYED M. , MOTAALEGHI M. AGHAYI
Published: November 2013

In this paper, active flutter suppression of a simply supported circular sandwich cylindrical shell with a tunable electrorheological fluid (ERF) core, under axial supersonic gas flow, is studied. The structural analysis is based on the classical thin shell theory, the ERF core is modeled as a first-order Kelvin–Voigt material, and the Krumhaar's modified supersonic piston theory is utilized to model the aerodynamic loading. Hamilton's principle is used to formulate the dynamic equations of motion together with the relevant boundary conditions. The generalized Fourier expansions in the circumferential and axial directions in conjunction with the classical Galerkin method are employed to set up the governing equations in the state-space domain. The critical free stream static pressures at which unstable oscillations arise are calculated for selected applied electric field strengths and cylinder length ratios. The Runge–Kutta time integration algorithm is used to determine the open-loop aeroelastic response of the system in two basic loading configurations, namely, a concentrated impulse point load and a sonic boom line load. Subsequently, a sliding mode control (SMC) strategy is adopted to actively suppress the closed loop system dynamic response in supersonic flight condition. Simulation results demonstrate performance and effectiveness of the adopted ERF-based SMC scheme. Limiting cases are considered and good agreements with the data available in the literature are obtained.
Minimization of vibration power transmission from rotating machinery to a flexible supporting plate
Authors: Niu B. , Olhoff N.
Published: November 2013

This paper deals with the problem of optimum design of a foundation for rotating machinery with a view to minimize vibration transmission from a machine source to its supporting structure. The problem of analysis and optimization of the installation systems of machinery has been extensively researched on the assumption of a rigid supporting structure. The design based on a rigid supporting structure model is reasonable for the installation of machinery in many real engineering situations. However, this rigid support based model may not be appropriate for the problem studied herein where the machinery is to be installed on a relatively flexible supporting plate. Thus, a generalized mathematical model of mobility power flow is developed in this paper, with a rotating machine as vibration source, resilient mounts as isolator, and a flexible supporting plate as receiver. The objective of minimizing vibration transmission is realized by optimization of stiffness coefficients of resilient mounts with a constraint on the vibration level of the machine. The design objective is chosen as the minimization of the power flow transmitted to the flexible supporting plate through the resilient mounts at the excitation frequency of the machinery. Both a single excitation frequency and a range of excitation frequencies are considered. A gradient-based mathematical programing method is selected for its advantage of efficiently solving the current type of optimization problem with multiple mounts and multi-degree-of-freedom vibration transmission. The sensitivities of the objective and the constraint functions with respect to the design variables are derived analytically. The design and performance of the optimized machinery foundation is illustrated and discussed using several numerical examples. The optimized mounting system is suitable for the installation case of a rotating machine with a low or medium service speed on a flexible supporting plate structure.
Paradoxical resistance to high-fat diet-induced obesity and altered macrophage polarization in mineralocorticoid receptor-overexpressing mice
Authors: Kuhn Emmanuelle , Bourgeois Christine , Keo Vixra , Viengchareun Say , Muscat Adeline , Meduri Geri , Le Menuet Damien , Fève Bruno , Lombès Marc
Published: November 2013

The mineralocorticoid receptor (MR) exerts proadipogenic and antithermogenic effects in vitro, yet its in vivo metabolic impact remains elusive. Wild type (WT) and transgenic (Tg) mice overexpressing human MR were subjected to standard chow (SC) or high-fat diet (HFD) for 16 wk. Tg mice had a lower body weight gain than WT animals and exhibited a relative resistance to HFD-induced obesity. This was associated with a decrease in fat mass, an increased population of smaller adipocytes, and an improved glucose tolerance compared with WT animals. Quantitative RT-PCR studies revealed decreased expression of PPARγ2, a master adipogenic gene, and of glucocorticoid receptor and 11β-hydroxysteroid dehydrogenase type 1, consistent with an impaired local glucocorticoid signaling in adipose tissues (AT). This paradoxical resistance to HFD-induced obesity was not related to an adipogenesis defect since differentiation capacity of Tg preadipocytes isolated from stroma-vascular fractions was unaltered, suggesting that other nonadipocyte factors might compromise AT development. Although AT macrophage infiltration was not different between genotypes, Tg mice exhibited a distinct macrophage polarization, as revealed by FACS analysis and CD11c/CD206 expression studies. We further demonstrated that Tg macrophage-conditioned medium partially impaired preadipocyte differentiation. Therefore, we propose that modification of M1/M2 polarization of hMR-overexpressing macrophages could account in part for the metabolic phenotype of Tg mice. Collectively, our results provide evidence that MR exerts a pivotal immunometabolic role by controlling adipocyte differentiation processes directly but also indirectly through macrophage polarization regulation. Our findings should be taken into account for the pharmacological treatment of metabolic disorders.
Synthesis and Characterizations of Poly(trimethylene terephthalate)-b-poly(tetramethylene glycol) Copolymers
Authors: Liu Feng , Yao Meng , Run Ming-tao
Published: November 2013

A series of poly(trimethylene terephthalate)-b-poly(tetramethylene glycol) (PTT-PTMEG) copolymers were synthesized by two-step melt-polycondensation. The copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR),1H NMR spectroscopy, rheometer, differential scanning calorimetry (DSC), polarized optical microscopy (POM), thermal gravimetric analysis (TGA), and mechanical properties. The results suggest that by increasing the flexible PTMEG contents from 0% to 60 wt%, the copolymers show decreased glass transition temperatures, melting points, melt-crystallization temperatures, hardness, tensile strength, thermostability, and smaller spherulites dimensions; however it has much increased impact strength and elongation at breaking point. Compared with commercial poly(butylene terephthalate) (PBT)-type TPEE with 25 mol% flexible segments, PTT-type TPEE having 25 mol% flexible segments has a lower glass transition temperature, melting point, crystallization temperature, and much lower tensile strength although it has a much higher impact strength than that of PBT-type TPEE, and it is not suitably used as a commercial TPEE.
Low Cost Amorphous Silicon Intrinsic Layer for Thin-Film Tandem Solar Cells
Authors: Wu Ching-In , Chang Shoou-Jinn , Lam Kin-Tak , Li Shuguang , Chang Sheng-Po
Published: November 2013

The authors propose a methodology to improve both the deposition rate and SiH4consumption during the deposition of the amorphous silicon intrinsic layer of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate. It was found that the most important issue is to find out the saturation point of deposition rate which guarantees saturated utilization of the sourcing gas. It was also found that amorphous silicon intrinsic layers with the samekvalue will result in the same degradation of the fabricated modules. Furthermore, it was found that we could significantly reduce the production cost of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate by fine-tuning the process parameters.
Ethnobotany and Ethnomedicinal Uses, Chromosomal Status and Natural Propagation of Some Plants of Lahaul-Spiti and Adjoining Hills
Authors: Kumar Puneet , Singhal Vijay Kumar
Published: November 2013

The present study documented the ethnobotanical and medicinal uses of plants from an ecologically fragile cold desert area of Lahaul-Spiti (Himachal Pradesh, India). Local people use plants for curing the stomach troubles, pain reliever, cough, gastric disorders, and aphrodisiac and other household purposes. In addition, chromosome numbers, male meiosis, and natural propagation were also investigated in these ethnobotanically used plants. Present investigations also form the basis for exploitation of intraspecific chromosomal variation/new cytotypes recorded in some of the presently studied species to detect biochemical diversity in the medicinally important plants. For documentation of ethnobotanical information, personal observations and interviews were conducted with medicine men, hakims, farmers, shepherds, local healers, and old aged people. This study identified 40 plant species under 33 genera belonging to 17 families which have been used locally for curing various diseases and other purposes. All the chromosome counts are new to the study area. On worldwide basis, meiotic chromosome counts of n=14 and n=8 in Rosularia alpestris and Corydalis govaniana, respectively, are the first ever reports. The present study indicates that the people of the area possess good knowledge about the different uses of plants in the area. It has been noticed that due to the lack of interest among younger generations in the preservation of invaluable ethnic knowledge, there is every possible chance of losing such a rich heritage of knowledge. It is very urgent to conserve such invaluable ethnic knowledge before it gets lost.
Application of Macrofiber Composite for Smart Transducer of Lamb Wave Inspection
Authors: Ren Gang , Jhang Kyung-Young
Published: November 2013

Macrofiber composite (MFC) has been developed recently as a new type of smart material for piezoelectric transducers. It shows advantages over traditional piezoelectric ceramic materials (PZT) including the method of application, sensitivity, and cost. It can be embedded on the structure, which provides the possibility to monitor the structural health in real time. In this paper, the feasibility of this transducer for the Lamb wave inspection has been experimentally explored. A pair of MFC patches is bonded on a 2 mm thick aluminum plate, and it has been demonstrated that the dispersive characteristics of S0 and A0 modes, generated and detected by MFC patches, agreed well with the theory. The influence of the bonding condition of the transducer was also tested to show that rigid bonding is required to assure a high amplitude signal. In order to illustrate the performance of defect detection, an artificial defect fabricated on the surface of a specimen was inspected in the pitch-catch mode. The results showed that the MFC transducer is a promising Lamb wave transducer for nondestructive testing (NDT) and structural health monitoring (SHM).
Analysis of Thermal Stability in a Convecting and Radiating Two-Step Reactive Slab
Authors: Makinde O. D. , Tshehla M. S.
Published: November 2013

This paper investigates the combined effects of convective and radiative heat loss on thermal stability of a rectangular slab of combustible materials with internal heat generation due to a two-step exothermic chemical reaction, taking the diffusion of the reactant into account and assuming a variable (temperature dependent) preexponential factor. The nonlinear differential equation governing the transient reaction-diffusion problem is obtained and tackled numerically using a semidiscretization finite difference technique. A special type of Hermite-Padé approximants coupled with perturbation technique are employed to analyze the effects of various embedded thermophysical parameters on the steady state problem. Important properties of the temperature field including thermal stability conditions are presented graphically and discussed quantitatively.
IFA and PIFA Size Reduction by Using a Stub Loading
Authors: Tirado-Mendez Jose Alfredo , Acevo-Herrera Rene , Flores-Leal Ruben , Linares-Miranda Roberto , Jardon-Aguilar Hildeberto
Published: November 2013

A proposed technique for size reduction of a conventional inverted-F antenna (IFA) and a planar inverted-F antenna (PIFA) by employing a reactive load generated by a short-circuited stub is presented. The reduction factor of both antennas is around 30%, and the main parameters of the devices are preserved, including a fractional bandwidth of 4% and a gain of −2 dB. Both antennas operate around 1.5 GHz.
Sodium Valproate Inhibits the Growth of Human CholangiocarcinomaIn VitroandIn Vivo
Authors: Wang Bing , Yang Rui , Wu Yue , Li Hongbo , Hu Zouxiao , Chen Yongjun , Zou Shengquan
Published: November 2013

Background. None of treatment options for Cholangiocarcinoma (CCA), including surgery, adjuvant radiotherapy and chemotherapy, and ultimately liver transplantation, have been shown to substantially improve the survival rate in patients with CCA. Valproic acid (VPA), a histone deacetylase inhibitor, has been shown to display potent antitumor effects. In this study, sodium valproate, the clinically available form of VPA, was tested for its ability to inhibit the growth of cholangiocarcinoma cells, bothin vitroandin vivo. Materials and Methods.Cholangiocarcinoma cells (TFK-1, QBC939, and CCLP1) of different origins were treated with sodium valproate to determine their effects on cell proliferation and differentiation, cell cycle regulation, apoptosis, and autophagy. Thein vivoeffects of sodium valproate on cholangiocarcinoma growth were assessed using a xenograft mouse model injected with TFK-1 cells.Results. Sodium valproate inhibited cholangiocarcinoma cell growth by inducing cell cycle arrest, cell differentiation, and apoptosis; sodium valproate effects were independent of autophagy. Tumor growth inhibition was also observedin vivousing TFK-1 xenografts.Conclusion. Thein vitroandin vivooutcomes provide preclinical rationale for clinical evaluation of sodium valproate, alone or in combination with other drugs, to improve patient outcome in cholangiocarcinoma.