bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation of Acoustic Energy Across a Turbine Stage With Subsonic Relative Flow
Authors: Bekofske Keith
Published: April 2015

The attenuation of sound energy propagating through a turbine is analyzed using an actuator disk theory. The analysis is restricted to low frequency disturbances and subsonic relative flow. Mach number changes and flow turning across a stage element are taken into account. Results indicate that the attenuation of acoustic energy across a typical turbine stage is at least 10 dB.
The Refracting Inlet: A New Concept for Aircraft Inlet Noise Suppression
Authors: Sloan D. , Farquhar B. W.
Published: April 2015

Observations of wave refraction in flowfields containing large transverse velocity gradients have suggested a means by which refraction effects could be used to aid suppression of the noise propagating forward through aircraft gas turbine inlets. The first part of this paper describes an experiment using a schlieren apparatus to observe waves passing through inlet-type flowfields. The second part describes a test program using model inlets to examine the feasibility of the refracting inlet concept.
Recuperator Development Trends for Future High Temperature Gas Turbines
Authors: McDonald C. F.
Published: April 2015

The current energy crisis and substantial increases in the costs of liquid and gaseous fuels, combined with reduced pollutant emission requirements, make the higher efficiency recuperative gas turbine cycle economically attractive for industrial and vehicular application. For future low cost, high temperature, small gas turbines, with improved cycle efficiencies, it is postulated that the complete hot section of the engine (combustor, ducts, turbine nozzle and rotor) will be all ceramic and may include a ceramic heat exchanger. Few of the answers are available today in the areas of ceramic recuperator performance, cost and structural integrity and concentrated development efforts are required to demonstrate the viability of a fixed boundary ceramic gas turbine heat exchanger. This paper briefly outlines possible design and development trends in the areas of exchanger configuration, surface geometry and materials, and it includes specific sizes and economic aspects of ceramic recuperators for future advanced low SFC gas turbines.
Graphic Design and Numerical Control Programming for Turbo-Rotor Manufacturing
Authors: Willis F. F.
Published: April 2015

Turbomachinery rotors may be engineered to be machined on 5-axis, numerically controlled machines using flank milling techniques. Engineering data can be converted to a graphic or computer data set which lends itself to unsophisticated numerically controlled programming for five-axis machines with short lead time production and a high degree of change flexibility.
Finite Element Approach to the Vibration Analysis of Elastic Disks on a Flexible Shaft
Authors: Kuo P. S.
Published: April 2015

The dynamic behavior of elastic circular disks mounted on a flexible rotor has been investigated by a three-dimensional finite element model (distributed masses). The results are discussed and compared with an equivalent system assuming rigid disks (concentrated mass) for the nonrotating case. Interactions between the disks and disk and shaft during resonances have been demonstrated. Natural modes of a disk component and of the entire structure, supported by flexible bearings, are shown by computer plots in orthographic projections.
Propagating Stall in Compressors With Porous Walls
Authors: Horlock J. H. , Lakhwani C. M.
Published: April 2015

A modification is presented to the Emmons/Stenning analysis for predicting stall propagation, taking into account the unsteady flow through the end wall of a cascade row of compressor blades. It is shown that if radial flow from the blade channels is permitted, then the condition for flow instability is changed. The expression obtained for the flow coefficient at which stall occurs indicates an improvement in operating range, with virtually no effect on stall cell speed. Experimental evidence suggests that a mechanism such as that described may be the reason for the delay in stall onset produced by porous wall treatment of axial compressors.
Cascade Research on a Small, Axial, High-Work, Cooled Turbine
Authors: Due H. F. , Easterling A. E. , Rogo C.
Published: April 2015

This paper presents the results of an experimental cascade investigation of the aerodynamic performance of a 1.524-cm (0.6-in.) blade height, low aspect ratio, highly loaded, cooled turbine. The experimental program was performed with a cold flow annual sector cascade with various geometric and aerodynamic perturbations. The perturbation included nozzle endwall contour, inlet turbulence and velocity distortion, stator and rotor solidity, rotor loading and nozzle cooling flow and point of injection. The turbine design evolved through a parametric analysis considering a turboshaft engine configuration required to have a 750-hr life at design power output and satisfy realistic mechanical constraints. The gas generator turbine configuration selected for investigation was a single-stage turbine with a turbine inlet temperature of 1316 C (2400 F) and an actual work output of 418.68 kJ/kg, (180 Btu/lb). The baseline turbine was sized for a stage work coefficient of 5.0 at the hub radius and an average flow coefficient of 0.675 for a best mechanical-aerothermodynamic compromise to meet realistic engine constraints.
A Method for Predicting the Performance of a Centripetal Gas Turbine Fitted With a Nozzle-Less Volute Casing
Authors: Kastner L. J. , Bhinder F. S.
Published: April 2015

A simple method for predicting the performance of a centripetal or inward flow radial gas turbine fitted with a nozzle-less volute casing is given. The accuracy of the analysis is shown by comparing the predicted and the measured performance characteristics of a small proprietary turbine. The flow diagram of the computer program has been included to describe the analytical procedure.
Field Testing the Performance of Gas Turbine Exhaust Heat Recovery Steam Generators
Authors: Bush G. W. , Godbey J. W.
Published: April 2015

This paper will present the results, to date, of the joint effort by the user-manufacturer coauthors to develop a reliable and generally accepted performance test procedure for gas turbine exhaust heat recovery steam generators. The knowledge and experience gained from several field tests will be detailed to support recommendations of procedures to follow and instrumentation to use in overcoming some very perplexing problems.
Structural Response of Fiber Composite Fan Blades
Authors: Chamis C. C. , Minich M. D.
Published: April 2015

A fiber composite airfoil, typical for high-tip speed compressor applications, is subjected to load conditions anticipated to be encountered in such applications, and its structural response is theoretically investigated. The analysis method used consists of composite mechanics embedded in pre- and post-processors and coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, centrifugal, and combinations of these. The various responses investigated include root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. Also, the core-shell concept for composite blades is an inefficient design (core plies not highly stressed) and appears to be sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for such an analysis, and to provide quantitative data of the various responses which can be helpful in designing such composite blades.
A Low Temperature Brittle Fracture Investigation of Gray Iron and Nodular Iron on Machinery Casings
Authors: Eisenstadt R. , Roulston G. H.
Published: April 2015

The resistance to brittle fracture of two iron alloys commonly used in machinery components is investigated. The Stress Intensity Factor (KI) is calculated using the principles of Fracture Mechanics, and is compared to available fracture toughness data in the form of Charpy Energies, and Plane Strain Fracture Toughness (KIc). Also presented are appropriate correlations to relate Charpy Energy and KIc. The critical flaw size (i.e., the flaw size necessary for brittle fracture) is also calculated and is presented in a generalized form which is applicable for various materials. The results of the investigation are evaluated, and the value of examining both Charpy and KIc data, particularly for irons, is discussed.
An Ultra High Temperature Turbine for Maximum Performance and Fuels Flexibility
Authors: Kydd P. H. , Day W. H.
Published: April 2015

The problems in water-cooled rotors have centered around the high pressuies generated in a closed circuit containing water by the high centrifugal field. The present program focusses on open circuit water cooling in which the water has been allowed to exit freely from the bucket tips. This eliminates the leaks and plugging of cooling channels that have been encountered before permits one to distribute the coolant uniformly around the bucket airfoil contour close to the surface. In this way the thermal gradients and thermal stresses on the airfoil can be held within safe limits. Using this approach a 9.7 in. (24.7 cm) diameter turbine wheel has been built and operated at inlet conditions of 2850 F (1560 C) and 16 atmosphere with tip speeds in excess of 1700 fps (518 m/sec) and with good aerodynamic efficiency. Recent developments in ceramic materials also indicate potential for use in stationary parts.
Approaches to the Prevaporized-Premixed Combustor Concept for Gas Turbines
Authors: Spadaccini L. J. , Szetela E. J.
Published: April 2015

An experimental investigation was performed to evaluate a combustor concept which is applicable to gas turbine engines and is believed to offer valuable pollution control advantages relative to the conventional liquid-fuel-spray approach. It involves fuel prevaporization, premixing and lean combustion and may be applied to the design of combustors for aircraft, industrial or automotive powerplants. Two types of bluff-body flameholders, viz. porous-plate and drilled-plate, were evaluated for use as flame stabilizers within the combustor. Tests were conducted under sets of steady-state operational conditions corresponding, respectively, to applications in a low-pressure regenerative-cycle and high-pressure nonregenerative-cycle automobile gas turbine engines. The data acquired can be used to design gas turbine combustors having predicted performance characteristics which are better than those required to meet the most stringent automobile emissions regulations of the Federal “Clean Air Act.” Fuel prevaporization can be accomplished either externally, prior to admission into the engine airstream, or internally by the airstream itself. In support of the prevaporization concept, the feasibility of vaporizing No 2 fuel oil in a heat exchanger which is external to the engine was investigated. Tests conducted at representative operating conditions indicated that a deposit of 0.01 0-in. thickness was collected on the vaporizer wall after 50 hr of operation. A much shorter period of cleaning with hot air was sufficient to remove the deposit.
Development of a High-Heat-Release Combustor for the F100 Gas Turbine
Authors: Holladay T. E. , Barlow G. C. , Henderson R. E.
Published: April 2015

The F100 turbofan engine is a twin-spool, augmented engine [89,000–133,000 Newton (20–30,000 lb) thrust range] that powers the McDonnell-Douglas/Air Force F-15 air superiority fighter. The F100 was developed jointly with the Navy F401 engine. These engines have a common core (gas generator). The success of these advanced high thrust/weight engines is, in part, the result of the development of a short, annular, high-heat-release rate primary combustor, which has a low temperature pattern factor, high combustion efficiency, and low pressure loss. The F100’s combustor uses conventional sheet metal louver cooling to minimize cost and weight, airblast fuel nozzles and combustor swirlers to atomize the fuel, and a dump diffuser to reduce the compressor air exit Mach number.
Understanding the Characteristics of Brittle Materials
Authors: Evans A. G.
Published: April 2015

The framework for characterizing and predicting failure when simple crack propagation control predominates is reasonably well understood. Since, in many ceramic systems, crack propagation appears to be the primary failure mode much of this paper is devoted to a description of the crack propagation process. Other failure modes, such as crack initiation and complex crack propagation control, are, unfortunately, in a rather rudimentary state of development; however, some discussion of situations where these might occur is presented.
Fine Tuning and Detailed Testing of a New Heavy Duty G.T. in the Field
Authors: Lerch C. P. , Wulff P. H.
Published: April 2015

Final field adjustments to optimize combustion and performance, as well as the comprehensive on site evaluation program performed on this gas turbine, are described in this paper. Included are a description of a series of minor combustion modifications which were easily possible due to the unique single-combustion-chamber design. Tests discussed included measurements of turbine blade operating temperatures and exhaust emissions.
The ST6 Gas Turbine in Trains Operating Experience
Authors: Coffin W. M.
Published: April 2015

This paper outlines the operating experience of the ST6 gas turbine installed in trains. Some of the problems encountered and the solutions used are discussed. The duty is compared to other more widely known duties. Some thoughts are offered for future applications of gas turbines to rail vehicles.
Maintenance of Industrial Gas Turbines
Authors: Knorr R. H. , Jarvis G.
Published: April 2015

This paper describes the maintenance requirements of the heavy-duty gas turbine. The various inspections and factors affecting maintenance are defined, and basic guidelines are presented for a planned maintenance program.
A Design Study of a Fan Augmented Ramjet
Authors: Beans E. W.
Published: April 2015

The characteristics of a hybrid propulsion system, which fills the gap between turbojets and ramjets, are presented. The hybrid system is a fan augmented ramjet and consists of a ramburner fed by an externally driven low pressure ratio fan. Cycle analyses, performance estimates and, scaling relationships for subsonic and supersonic operation, and a preliminary design of a subsonic version are presented. A 50 to 100 percent improvement in cruise performance above that of a ramjet can be expected in the subsonic regime.
Internal viscoelastic flows for fluids with exponential type pressure-dependent viscosity and relaxation time
Authors: Housiadas Kostas D.
Published: April 2015

The isothermal steady-state and pressure-driven flows in a straight channel and a circular tube, of an incompressible viscoelastic fluid which follows the Maxwell constitutive model, are considered. Under the assumption that both the shear viscosity and the single relaxation time of the fluid vary exponentially with pressure, the governing equations are solved analytically using a regular perturbation scheme with small parameter the dimensionless pressure-viscosity coefficient. The solution is found up to sixth order in the small parameter, revealing a two-dimensional (2D) flow field and the dependence of the primary flow variables on the geometrical aspect ratio, the pressure-viscosity coefficient, and the Weissenberg and Reynolds numbers. It is demonstrated that the pressure-dependent viscosity and relaxation time enhance the pressure gradient along the main flow direction, generate another along the wall-normal direction, and cause vertical motion of the fluid. Viscoelastic extra-stresses, which affect significantly the average pressure difference, required to drive the flow and the shear stress at the wall, are also predicted. Moreover, the mean Darcy friction factor shows a substantial deviation from the average pressure difference, as the fluid elasticity increases. For the Newtonian fluid, the effect of the pressure-dependent viscosity on the velocity components is minor, but substantial on the pressure and shear-stress profiles. Most of these features are predicted for the first time, and they are due to the fact that the flow field is fully 2D, indicating the complex nature of fluids with pressure-dependent viscosity and relaxation time.
Synchronous Motor Pull-in Process Analysis
Authors: Vainer Zvi , Epshtein Boris , Tapuchi Saad , Horen Yoram , Strajnikov Pavel , Averbukh Moshe , Kuperman Alon
Published: April 2015

In this paper, simple approach to analyzing the starting procedure of synchronous motors (SMs) is presented with an emphasis on the pull-in process. Instead of the classical, mostly intuitive pulling-repelling torque approach, an analytical method based on the motor mechanical part swing equation is employed. Factors affecting starting and pull-in processes are clearly indicated and torque impulse balance leading to a pull into step is revealed. It is shown that if the motor fails to pull into step within a single oscillation, it can still be synchronized during one of the succeeding acceleration periods. The crucial role of the excitation winding energizing instant is demonstrated as well. Moreover, the revealed similarity between the SM and phase locked loop (PLL) operations, leads to the conclusion that the algorithms use for analyzing the operation of one may be employed for investigating the other. Experimental results are given to demonstrate the different scenarios, mentioned in the manuscript.
Uniqueness of reduced alternating rational 3-tangle diagrams
Authors: Kwon Bo-Hyun
Published: April 2015

Tangles were introduced by J. Conway. In 1970, he proved that every rational 2-tangle defines a rational number and two rational 2-tangles are isotopic if and only if they have the same rational number. So, from Conway's result we have a perfect classification for rational 2-tangles. However, there is no similar theorem to classify rational 3-tangles. In this paper, we introduce an invariant of rational n-tangles which is obtained from the Kauffman bracket. It forms a vector with Laurent polynomial entries. We prove that the invariant classifies the rational 2-tangles and the reduced alternating rational 3-tangles. We conjecture that it classifies the rational 3-tangles as well.
ADSORPTION AND DISSOCIATION OF O2 ON Ti3Al (0001) STUDIED BY FIRST-PRINCIPLES
Authors: WEI LI-JING , GUO JIAN-XIN , DAI XIU-HONG , WANG YING-LONG , LIU BAO-TING
Published: April 2015

The adsorption and dissociation of oxygen molecule on Ti 3 Al (0001) surface have been investigated by density functional theory (DFT) with the generalized gradient approximation (GGA). All possible adsorption sites including nine vertical and fifteen parallel sites of O 2 are considered on Ti 3 Al (0001) surface. It is found that all oxygen molecules dissociate except for three vertical adsorption sites after structure optimization. This indicates that oxygen molecules prefer to dissociate on the junction site between Ti and Al atoms. Oxygen atoms coming from dissociation of oxygen molecule tend to occupy the most stable adsorption sites of the Ti 3 Al (0001) surface. The distance of O – O is related to the surface dissociation distance of Ti 3 Al (0001) surface. The valence electron localization function (ELF) and projected density of states (DOS) show that the bonds of O – O are breakaway at parallel adsorption end structures.
POSTERIOR ELEMENT MORPHOLOGY AND DEGENERATIVE LUMBAR SPONDYLOLISTHESIS
Authors: Moon Myung-Sang , Yoon Min-Keun , Kwon Ki-Tae , Park Min-Suk , Park Bong-Keun , Kim Sung-Soo
Published: April 2015

Study design: Retrospective radiographic studies on lumbar facet morphology, and facet and laminar inclination angles. Objectives: To investigate the effect of the facet morphology, facet and laminar inclination angles on development of the segmental instability and spondylolisthesis. Summary of background data: Many previous papers related with the facet shape on pathogenesis of the degenerative instability and spondylolisthesis were published. Most authors interpreted that the facet morphology in the pathogenesis of the spondylolisthesis was a factor secondary to facet joint osteoarthritis, and was not the primary one. None dealt the effect of facet shape and laminar inclination on slippage severity. Method: The subject materials were 50 patients (10 males and 40 females) with degenerative spondylolisthesis, treated between 1999 and 2013. Simple radiograms were utilized for assessment. Facet joints were classified by Tsunoda et al., based on its developmental shape and alignment on radiograms; X, M, and W types. Also the laminar inclination and facet inclination angles were measured. Results: Among 50 patients 45 had anterolisthesis with (forward flexion instability) and only five had retrolisthesis (extension instability). In 45 cases of anterolisthesis, there were 24 "X" types, 4 "M" types, and 17 "W" types, while in 5 cases of retrolisthesis there were 3 "X" and 2 "M" types. In 45 cases of anterolisthesis, 24 with "X" type facets had Myerding's grade I slip, and one had grade II slip; Among the 4 "M" types two had grade I slip and two had grade II slip, while among 17 "W" type, there were four grade I slip, 11 grade II slip, and two grade III slip. 13 out of the 16 anterolisthesis over grade II slip had "W" type facets. Vertebra with "W" type facets had average 130° laminar inclination angle and 122° facet inclination angles, while "X" and "M" type facets had less inclination of both angles. Conclusion: The defective facet morphology and laminar inclination angle of the lower lumbar spine can be the predisposing factor of development and slip progress of the degenerative anterolisthesis.
Stochastic Resonance in Time-to-Contact Judgments
Authors: Ranjit Manish , Gazula Harshvardhan , Hsiang Simon M. , DeLucia Patricia R.
Published: April 2015

Stochastic resonance (SR) is a counterintuitive phenomenon in which additive noise enhances performance of a nonlinear system. Previous studies demonstrated SR effect on human tactile sensitivity by adding noise of same modality and cross modality. Similarly, enhancement of human hearing through additive noise has been studied. In this study, we investigate the effect of noise in visual perception, specifically time-to-contact (TTC) judgments. This study explores four research questions: (1) Does noise help in TTC judgments? (2) How does noise affect speed and accuracy of TTC judgments? (3) Does cross modal noise help in TTC judgments? (4) How does cross modal noise affect speed and accuracy of TTC judgments? Through simulation, we show that noise in optical cue can enhance weak signals. We also demonstrate that noise can improve speed of TTC judgments at the expense of accuracy. Similarly, we demonstrate SR by adding noise of cross modality. These findings provide plausible hypotheses regarding how much noise should be added to enhance TTC judgments.
Entrance time and Rényi entropy
Authors: Gupta Chinmaya , Haydn Nicolai , Ko Milton , Rada-Mora Erika A.
Published: April 2015

For ergodic systems with generating partitions, the well-known result of Ornstein and Weiss shows that the exponential growth rate of the recurrence time is almost surely equal to the metric entropy. Here we look at the exponential growth rate of entrance times, and show that it equals the entropy, where the convergence is in probability in the product measure. This is however under the assumptions that the limiting entrance times distribution exists almost surely. This condition looks natural in the light of an example by Shields in which the limsup in the exponential growth rate is infinite almost everywhere but where the limiting entrance times do not exist. We then also consider ϕ-mixing systems and prove a result connecting the Rényi entropy to sums over the entrance times orbit segments.
Shock Wave Instability in a Channel with an Expansion Corner
Authors: Kuzmin A.
Published: April 2015

2D and 3D transonic flows in a channel of variable cross-section are studied numerically using a solver based on the Reynolds-averaged Navier–Stokes equations. The flow velocity is supersonic at the inlet and outlet of the channel. Between the supersonic regions, there is a local subsonic region whose upstream boundary is a shock wave, whereas the downstream boundary is a sonic surface. The sonic surface gives rise to an instability of the shock wave position in the channel. Computations reveal a hysteresis in the shock position versus the inflow Mach number. A dependence of the hysteresis on the velocity profile given at the inlet is examined.
Davenport's theorem in geometric discrepancy theory
Authors: Chen W. W. L.
Published: April 2015

Davenport's theorem was established nearly a lifetime ago, but there have been some very interesting recent developments. The various proofs over the years bring in different ideas from number theory, probability theory, analysis and group theory. In this short survey, we shall not present complete proofs, but will describe instead some of these underlying ideas.
Simulation and quantitative analysis of fluorescence intensity distribution based on the Monte Carlo method
Authors: Zhou Kun , Tian Jian , Zhang Qiushi , Meng Xiangxi , Yang Kun , Ren Qiushi
Published: April 2015

The Monte Carlo method is a versatile simulation algorithm to model the propagation of photons inside the biological tissues. It has been applied to the reconstruction of the fluorescence molecular tomography (FMT). However, such method suffers from low computational efficiency, and the time consumption is not desirable. One way to solve this problem is to introduce a priori knowledge which will facilitate iterative convergence. We presented an in vivo simulation environment for fluorescence molecular tomography (ISEFMT) using the Monte Carlo method to simulate the photon distribution of fluorescent objects and their sectional view in any direction quantitatively. A series of simulation experiments were carried out on different phantoms each with two fluorescent volumes to investigate the relationship among fluorescence intensity distribution and the excitation photon number, the locations and sizes of the fluorescence volumes, and the anisotropy coefficient. A significant principle was discovered, that along the direction of the excitation light, the fluorescent volume near the excitation point will provide shelter effect so that the energy of the fluorescent volume farther away from the excitation point is relatively lower. Through quantitative analysis, it was discovered that both the photon energy distribution on every cross section and the fluorescence intensity distributed in the two volumes exhibit exponential relationships. The two maximum positions in this distribution correspond to the centers of fluorescent volumes. Finally, we also explored the effect of the phantom coefficients on the exponential rule, and found out that the exponential rule still exists, only the coefficient of the exponential rule changed. Such results can be utilized in locating the positions of multiple fluorescent volumes in complicated FMT reconstruction involving multiple fluorescent volumes. Thus, a priori knowledge can be generalized, which would accelerate the reconstruction of FMT and even other images.
Modulation of Th1/Th2 Immune Responses by KilledPropionibacterium acnesand Its Soluble Polysaccharide Fraction in a Type I Hypersensitivity Murine Model: Induction of Different Activation Status of Antigen-Presenting Cells
Authors: Squaiella-Baptistão Carla Cristina , Teixeira Daniela , Mussalem Juliana Sekeres , Ishimura Mayari Eika , Longo-Maugéri Ieda Maria
Published: April 2015

Propionibacterium acnes(P. acnes) is a gram-positive anaerobic bacillus present in normal human skin microbiota, which exerts important immunomodulatory effects, when used as heat- or phenol-killed suspensions. We previously demonstrated that heat-killedP. acnesor its soluble polysaccharide (PS), extracted from the bacterium cell wall, suppressed or potentiated the Th2 response to ovalbumin (OVA) in an immediate hypersensitivity model, depending on the treatment protocol. Herein, we investigated the mechanisms responsible for these effects, using the same model and focusing on the activation status of antigen-presenting cells (APCs). We verified that higher numbers of APCs expressing costimulatory molecules and higher expression levels of these molecules are probably related to potentiation of the Th2 response to OVA induced byP. acnesor PS, while higher expression of toll-like receptors (TLRs) seems to be related to Th2 suppression.In vitrocytokines production in cocultures of dendritic cells and T lymphocytes indicated thatP. acnesand PS seem to perform their effects by acting directly on APCs. Our data suggest thatP. acnesand PS directly act on APCs, modulating the expression of costimulatory molecules and TLRs, and these differently activated APCs drive distinct T helper patterns to OVA in our model.
Modulation of Immune Response by Organophosphorus Pesticides: Fishes as a Potential Model in Immunotoxicology
Authors: Díaz-Resendiz K. J. G. , Toledo-Ibarra G. A. , Girón-Pérez M. I.
Published: April 2015

Immune response is modulated by different substances that are present in the environment. Nevertheless, some of these may cause an immunotoxic effect. In this paper, the effect of organophosphorus pesticides (frequent substances spilled in aquatic ecosystems) on the immune system of fishes and in immunotoxicology is reviewed. Furthermore, some cellular and molecular mechanisms that might be involved in immunoregulation mechanisms of organophosphorus pesticides are discussed.
Artificial Neural Network Modeling for Spatial and Temporal Variations of Pore-Water Pressure Responses to Rainfall
Authors: Mustafa M. R. , Rezaur R. B. , Rahardjo H. , Isa M. H. , Arif A.
Published: April 2015

Knowledge of spatial and temporal variations of soil pore-water pressure in a slope is vital in hydrogeological and hillslope related processes (i.e., slope failure, slope stability analysis, etc.). Measurements of soil pore-water pressure data are challenging, expensive, time consuming, and difficult task. This paper evaluates the applicability of artificial neural network (ANN) technique for modeling soil pore-water pressure variations at multiple soil depths from the knowledge of rainfall patterns. A multilayer perceptron neural network model was constructed using Levenberg-Marquardt training algorithm for prediction of soil pore-water pressure variations. Time series records of rainfall and pore-water pressures at soil depth of 0.5 m were used to develop the ANN model. To investigate applicability of the model for prediction of spatial and temporal variations of pore-water pressure, the model was tested for the time series data of pore-water pressure at multiple soil depths (i.e., 0.5 m, 1.1 m, 1.7 m, 2.3 m, and 2.9 m). The performance of the ANN model was evaluated by root mean square error, mean absolute error, coefficient of correlation, and coefficient of efficiency. The results revealed that the ANN performed satisfactorily implying that the model can be used to examine the spatial and temporal behavior of time series of pore-water pressures with respect to multiple soil depths from knowledge of rainfall patterns and pore-water pressure with some antecedent conditions.
Repetitive Hyperbaric Oxygenation Attenuates Reactive Astrogliosis and Suppresses Expression of Inflammatory Mediators in the Rat Model of Brain Injury
Authors: Lavrnja Irena , Parabucki Ana , Brkic Predrag , Jovanovic Tomislav , Dacic Sanja , Savic Danijela , Pantic Igor , Stojiljkovic Mirjana , Pekovic Sanja
Published: April 2015

The exact mechanisms by which treatment with hyperbaric oxygen (HBOT) exerts its beneficial effects on recovery after brain injury are still unrevealed. Therefore, in this study we investigated the influence of repetitive HBOT on the reactive astrogliosis and expression of mediators of inflammation after cortical stab injury (CSI). CSI was performed on male Wistar rats, divided into control, sham, and lesioned groups with appropriate HBO. The HBOT protocol was as follows: 10 minutes of slow compression, 2.5 atmospheres absolute (ATA) for 60 minutes, and 10 minutes of slow decompression, once a day for 10 consecutive days. Data obtained using real‐time polymerase chain reaction, Western blot, and immunohistochemical and immunofluorescence analyses revealed that repetitive HBOT applied after the CSI attenuates reactive astrogliosis and glial scarring, and reduces expression of GFAP (glial fibrillary acidic protein), vimentin, and ICAM‐1 (intercellular adhesion molecule‐1) both at gene and tissue levels. In addition, HBOT prevents expression of CD40 and its ligand CD40L on microglia, neutrophils, cortical neurons, and reactive astrocytes. Accordingly, repetitive HBOT, by prevention of glial scarring and limiting of expression of inflammatory mediators, supports formation of more permissive environment for repair and regeneration.
The Danger Model Approach to the Pathogenesis of the Rheumatic Diseases
Authors: Pacheco-Tena César , González-Chávez Susana Aideé
Published: April 2015

The danger model was proposed by Polly Matzinger as complement to the traditional self-non-self- (SNS-) model to explain the immunoreactivity. The danger model proposes a central role of the tissular cells’ discomfort as an element to prime the immune response processes in opposition to the traditional SNS-model where foreignness is a prerequisite. However recent insights in the proteomics of diverse tissular cells have revealed that under stressful conditions they have a significant potential to initiate, coordinate, and perpetuate autoimmune processes, in many cases, ruling over the adaptive immune response cells; this ruling potential can also be confirmed by observations in several genetically manipulated animal models. Here, we review the pathogenesis of rheumatic diseases such as systemic lupus erythematous, rheumatoid arthritis, spondyloarthritis including ankylosing spondylitis, psoriasis, and Crohn’s disease and provide realistic approaches based on the logic of the danger model. We assume that tissular dysfunction is a prerequisite for chronic autoimmunity and propose two genetically conferred hypothetical roles for the tissular cells causing the disease: (A) the Impaired cell and (B) the paranoid cell. Both roles are not mutually exclusive. Some examples in human disease and in animal models are provided based on current evidence.
Alzheimer’s Pathogenesis and Its Link to the Mitochondrion
Authors: Simoncini C. , Orsucci D. , Caldarazzo Ienco E. , Siciliano G. , Bonuccelli U. , Mancuso M.
Published: April 2015

Alzheimer’s disease (AD) is the most common form of dementia in the elderly. This neurodegenerative disorder is clinically characterized by impairment of cognitive functions and changes in behaviour and personality. The pathogenesis of AD is still unclear. Recent evidence supports some role of mitochondria dysfunction and oxidative stress in the development of the neurodegenerative process. In this review, we discuss the role of mitochondrial dysfunction in AD, focusing on the mechanisms that lead to mitochondrial impairment, oxidative stress, and neurodegeneration, a “vicious circle” that ends in dementia.
Partial Storage Optimization and Load Control Strategy of Cloud Data Centers
Authors: Al Nuaimi Klaithem , Mohamed Nader , Al Nuaimi Mariam , Al-Jaroodi Jameela
Published: April 2015

We present a novel approach to solve the cloud storage issues and provide a fast load balancing algorithm. Our approach is based on partitioning and concurrent dual direction download of the files from multiple cloud nodes. Partitions of the files are saved on the cloud rather than the full files, which provide a good optimization to the cloud storage usage. Only partial replication is used in this algorithm to ensure the reliability and availability of the data. Our focus is to improve the performance and optimize the storage usage by providing the DaaS on the cloud. This algorithm solves the problem of having to fully replicate large data sets, which uses up a lot of precious space on the cloud nodes. Reducing the space needed will help in reducing the cost of providing such space. Moreover, performance is also increased since multiple cloud servers will collaborate to provide the data to the cloud clients in a faster manner.
A Multiple Attribute Group Decision Making Approach for Solving Problems with the Assessment of Preference Relations
Authors: Yang Taho , Kuo Yiyo , Parker David , Chen Kuan Hung
Published: April 2015

A number of theoretical approaches to preference relations are used for multiple attribute decision making (MADM) problems, and fuzzy preference relations is one of them. When more than one person is interested in the same MADM problem, it then becomes a multiple attribute group decision making (MAGDM) problem. For both MADM and MAGDM problems, consistency among the preference relations is very important to the result of the final decision. The research reported in this paper is based on a procedure that uses a fuzzy preference relations matrix which satisfies additive consistency. This matrix is used to solve multiple attribute group decision making problems. In group decision problems, the assessment provided by different experts may diverge considerably. Therefore, the proposed procedure also takes a heterogeneous group of experts into consideration. Moreover, the methods used to construct the decision matrix and determine the attribution of weight are both introduced. Finally a numerical example is used to test the proposed approach; and the results illustrate that the method is simple, effective, and practical.
Interleukin 1β-Responsive MicroRNA-146a Is Critical for the Cytokine-Induced Tolerance and Cross-Tolerance to Toll-Like Receptor Ligands
Authors: Nahid Md A. , Satoh Minoru , Chan Edward K.L.
Published: April 2015

Unwarranted overproduction of cytokines, such as interleukin (IL)-1β, can cause moderate to severe pathological complications, and thus elaborate mechanisms are needed to regulate its onset and termination. One such, well-known, mechanism is endotoxin tolerance, generally described as controlling lipopolysaccharide Toll-like receptor 4 (LPS-TLR4) signaling. Similarly, cytokine-induced tolerance plays an important role in regulating an overactive cytokine response. In this report, the capability of IL-1β to induce tolerance and cross-tolerance to various inflammatory ligands was investigated. IL-1β-stimulated THP-1 monocytes showed a gradual increase of microRNA (miR)-146a, reaching 15-fold expression by 24 h. miR-146a upregulation induced tolerance toward subsequent challenges of IL-1β, LPS, peptidoglycan, Pam and flagellin in THP-1 cells. The induction of tolerance was dependent on the IL-1β priming dose and associated increase of miR-146a expression. Moreover, IL-1β-treated THP-1 cells showed sustained miR-146a upregulation that repressed IRAK1 and TRAF6 adaptor molecules. Transfection of miR-146a alone mimicked IL-1β-induced tolerance in monocytes, while cells transfected with miR-146a inhibitor increased chemokine production. A comparable cytokine response regulated by miR-146a was also detected in lung epithelial A549 cells, purified human monocytes and mouse peritoneal macrophages. Thus, our studies showed that miR-146a was crucial for monocytic cell-based IL-1β tolerance and cross-tolerance, and thus opens the way for future research in the development of therapeutics for inflammatory diseases.
Ex vivo Human Corneal Epithelial Cell Expansion from a Xeno-Feeder-Free System
Authors: Na Kyung-Sun , Mok Jee Won , Joo Choun-Ki
Published: April 2015

Purpose: The purpose of this study was to establish a simple, xeno-feeder-free method for cultivating human corneal epithelial cells. Methods: Limbal tissue explants from a cadaver were cultured in Iscove's modified Dulbecco's medium and low-calcium Panserin 801 medium in a 1:1 ratio. The outgrowing cells were characterized by flow cytometry, immunohistochemistry and real-time PCR (rtPCR). Limbal epithelial cells were expanded in a xeno-feeder-free, low-calcium medium and airlifted for 2 weeks each. Results: Migration of fibroblast-like stromal cells initially occurred from the limbal explants, and then epithelial cells migrated and grew on the stromal cells as an autofeeder layer. After airlifting, the cultured epithelium consisted of two to three layers. The cultured cells expressed stem cell-associated markers (ABCG2 and ΔNp63), differentiation markers (CK3 and CK12) and extracellular matrix-associated markers (lumican and decorin). rtPCR showed increased expression of markers for epithelial progenitor cells compared to fresh limbal tissue. Side population cells comprised 0.43 ± 0.04% of the cells (n = 5) in the primary culture. Flow cytometry showed that 49.12, 40.44 and 44.55% of the cells from the explants expressed E-cadherin, ΔNp63 and ABCG2, respectively. Conclusion: This explant culture system using stromal cells as an autofeeder layer was useful in expanding human corneal epithelial cells. This system may offer clinical insight for the expansion of limbal progenitor cells for the reconstruction of the ocular surface.
A Matter of Interpretation: Constructing and Interpreting Commercial Contracts under the Common Law and the Convention on the International Sale of Goods
Authors: Wade Gordon
Published: April 2015

Contractual disputes concerning interpretation can be the most intractable of all contractual disputes and their outcome is notoriously difficult to predict. The interpretation of contradictory or ambiguous contractual provisions may often be necessary in order to determine, inter alia, the effect of the parties’ actions upon the performance of the contract and what the substantive contractual obligations actually are. Contractual interpretation in civil law and common law jurisdictions proceeds from fundamentally different perspectives, particularly when viewed in light of a recognised international private law convention, the cisg. Comparing and contrasting the common law and the cisg shows the latter to be the product of a diplomatic conference comprising 62 States and eight international organisations and not a series of ancient pronouncements of English judges who developed commercial law through 19th century sensibilities. The cisg and the common law are, however, not poles apart but the cisg was born because commercial trading, commercial agreements and the parties involved have become increasingly internationalised, complex and sophisticated.
Balancing Free Trade Principles with Other Constitutional Provisions in the Context of Preferential Trade Agreements
Authors: Lizarazo-Rodríguez Liliana , De Lombaerde Philippe
Published: April 2015

Colombia’s Constitution of 1991 is an ambitious text which tries to strike a balance between laying a strong foundation for economic modernization and liberalization, on the one hand, and the creation of a Social State of Law and the protection of an impressive list of constitutional rights, on the other. Because of the doctrine that has been developed by the Constitutional Court since then, it has been considered as one of the most activist courts worldwide, next to courts such as the South African court. One of the factors that has thereby complicated its task is the fact that, since the 1990s, the government has actively multiplied its international economic commitments.

In this article, case law of the Colombian Constitutional Court is analyzed, with a focus on balancing: (a) between the binding character of (regional and bilateral) free trade commitments and the constitutional competences of the sub-national level, and (b) between international free trade commitments and the protection of constitutional social rights. Both cases shed light on the balancing task of the court in a complex international context, in the presence of a multi-level regulatory architecture.
Nonhydrostatic Wave Generation at Strained Fronts
Authors: Shakespeare Callum J.
Published: April 2015

A simple analytical model is developed to describe wave generation during frontogenesis forced by a horizontal strain field. In contrast to previous models, neither geostrophic nor hydrostatic balance is assumed. The generated waves are trapped in the strain field and form steady bands of enhanced vertical flow on either side of the surface front on scales from 1 to 100 km. The predictions of the analytical model are confirmed by comparison with fully nonlinear numerical simulations.
The recess renaissance
Authors: Keeler Rusty
Published: April 2015

The author tells of his work around the country and world on transforming how schools do recess, free play, and outside time by transforming their outdoor spaces to match. Instead of a playground of fixed structures like traditional school grounds, newer spaces are filled with loose materials that children can use to build forts, dens, and tree houses, complete with running water, sand play areas, and fire pits for cooking. Creating optimum play and learning opportunities requires three elements: time, space, and materials. One example of this is the Hands-on-Nature Anarchy Zone at Ithaca Children’s Garden in Ithaca, N.Y. It is one of the leading examples of a child-structured, play-based environment.
It all adds up
Authors: Ramani Geetha B. , Eason Sarah H.
Published: April 2015

Playing and learning mathematics do not have to be mutually exclusive activities, especially in kindergarten. Play and games can give young children opportunities to learn and develop foundational math skills that are aligned with Common Core standards for mathematics through age-appropriate, fun, and engaging activities.
Ed Law
Authors: Darden Edwin C.
Published: April 2015

In 1984, Congress passed Equal Access Act, a measure grounded in free speech principles under the First Amendment to the U.S. Constitution. Put simply, if a public school district recognizes any noncurriculum high school club, it must allow any other club to exist without prejudice. That is a powerful statement — and one with court cases to back it up.
Backtalk
Authors: Murphy Joseph
Published: April 2015

Five intelligences comprise the DNA of leadership: banked intelligence, fluid intelligence, connected intelligence, relational intelligence, and operational intelligence. Thinking of the intelligences of leadership provides an especially robust architecture for analyzing the work, helping leaders understand why certain actions worked and why others did not and pinpointing where intelligences need to be enhanced.
Multi-component wind turbine modeling and simulation for wind farm operations and maintenance
Authors: Pérez Eduardo , Ntaimo Lewis , Ding Yu
Published: April 2015

Wind farms produce electricity and provide a source of renewable energy. The growth in wind farm installations in the past 10 years has led to an increase in the number of wind turbines reaching the end of their manufacturing warranties. As a consequence, the wind industry is now facing a rising cost of unscheduled maintenance, which is pushing up the operation and maintenance expenditures. Wind turbines experience stochastic loading due to seasonal variations in wind speed and direction. These harsh operational conditions lead to failures of wind turbine components, which are difficult to predict. Consequently, it is challenging to schedule maintenance actions that will avoid failures. In this paper, we derive algorithms for scheduling wind farm maintenance for wind turbines modeled explicitly as comprising multiple components: the gearbox, power generator, blades and control system. We perform simulations based on a real wind farm with 100 turbines and report on several wind farm performance measures. The results we obtain provide insights regarding how to efficiently manage limited maintenance resources in wind farms. For example, the results show that maintenance policies that consider performing maintenance on multiple components of a wind turbine on the same maintenance scheduled trip provides significant cost savings while reducing the number of turbine failures.