bluuebunny/crossref_metadata_2025 huggingface dataset:
A Shift in Federal Policy Regulation of the Automobile Industry: Policy Brokers and the ACF
Authors: Diaz‐Kope Luisa M. , Lombard John R. , Miller‐Stevens Katrina
Published: September 2013

The advocacy coalition framework (ACF) provides a means to explore complex policy issues and the dynamics of belief systems shared by multiple actors in the policy‐making process. Using a single case study, this article expands the application of the ACF to the complex policy subsystem of the U.S. automobile industry during the 2009 auto bailout and subsequent bankruptcy of General Motors and Chrysler. We examine the development and actions of policy coalitions and further expand the ACF by exploring the role of policy brokers during the automobile crisis. We also examine whether policy brokers are politically neutral actors as previous research debates and what actions they take if compromise cannot be reached between competing coalitions.

Related Articles

Hallock Morris, Mary. 2007. “.” Politics & Policy 35 (): 836‐871. http://onlinelibrary.wiley.com/doi/10.1111/j.1747‐1346.2007.00086.x/abstract

Shanahan, Elizabeth, Mark McBeth, and Paul Hathaway. 2011. “.” Politics & Policy 39 (): 373‐400. http://onlinelibrary.wiley.com/doi/10.1111/j.1747‐1346.2011.00295.x/abstract

Buckner, John R. 1993. “.” Southeastern Political Review 21 (): 219‐237. http://onlinelibrary.wiley.com/doi/10.1111/j.1747‐1346.1993.tb00360.x/abstract

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Manning, Stephen. 2009. “.” . December 3. http://seattletimes.com/html/businesstechnology/2010418674_apusautodelalers.html
Anger, Exposure to Violence, and Intragroup Conflict: A “Lab in the Field” Experiment in Southern Israel
Authors: Zeitzoff Thomas
Published: September 2013

I examine how anger stemming from violence in the Israel‐Palestine conflict influences intragroup retaliation. In July 2010 I conducted a series of experiments in two cities in the Southern District of Israel affected to varying degrees (high and low) by rocket fire from the Gaza Strip. For each experiment, subjects were partnered anonymously with a member of their community. They were then exposed to one of two emotional manipulations: one that induced anger or one that did not. Finally, each subject was given an opportunity to keep an endowment or allocate it towards destroying a portion, or all, of their partner's income (“pay to punish”) in retaliation for their partner having taken money from them previously. This decision to “pay to punish” was designed to closely mimic the costly nature of conflict. The findings suggest that anger has a conditional effect on decisions to pay to punish: in Sderot (most affected by rocket fire), anger decreases punishment, while in Ofakim (less affected), it increases punishment. Additionally, higher exposure to violence made subjects more likely to engage in negative reciprocity.
Are Citizens “Receiving the Treatment”? Assessing a Key Link in Contextual Theories of Public Opinion and Political Behavior
Authors: Newman Benjamin J. , Velez Yamil , Hartman Todd K. , Bankert Alexa
Published: September 2013

The theorization and empirical exploration of contextual effects is a long‐standing feature of public opinion and political behavior research. At present, however, there is little to no evidence that citizens actually perceive the local contextual factors theorized to influence their attitudes and behaviors. In this article, we focus on two of the most prevalent contextual factors appearing in theories—racial/ethnic and economic context—to investigate whether citizens' perceptions of their local ethnic and economic contexts map onto variation in the actual ethnic composition and economic health of these environments. Using national survey data combined with Census data, and focusing on the popular topics of immigration and unemployment, we find that objective measures of the size of the immigrant population and unemployment rate in respondents' county and zip code strongly predict perceived levels of local immigration and assessments of the health of one's local job market. In addition to demonstrating that citizens are “receiving the treatment,” we show that perceptions of one's context overwhelmingly mediate the effect of these objective contextual factors on relevant economic and immigration attitudes. The results from our analyses provide scholars with unprecedented evidence that a key perceptual process presumed in various contextual theories of political attitudes and behavior is, in fact, valid.
Story Coalitions: Applying Narrative Theory to the Study of Coalition Formation
Authors: Shenhav Shaul R. , Oshri Odelia , Ofek Dganit , Sheafer Tamir
Published: September 2013

This article explores the potential of incorporating narrative theory into the study of coalition formation. Following a discussion of the role of narratives in group‐formation processes in a coalition‐driven dynamic, we offer a theoretical framework to examine the ways political stories espoused by people are mirrored by the partisan system. We integrate theoretical assumptions of narrative studies with coalition‐formation theories in an attempt to frame coalition‐formation models in terms of voters' political stories. We test our theoretical framework by simulating various possible coalitions in the Israeli 2009 elections and assess the results based upon data from an exit poll survey.
Ejaculate Fractioning Effect on Llama Sperm Head Morphometry as Assessed by theISAS® CASAsystem
Authors: Soler C , Sancho M , García A , Fuentes MC , Núñez J , Cucho H
Published: September 2013

Contents

South American camelid sperm characteristics are poorly known compared with those of other domestic animals. The long‐term duration of ejaculation makes difficult to gather all the seminal fluid, implying possible ejaculation portion losses. Thus, the aim of this research was to evaluate the characteristics of the morphology and morphometry of the spermatozoa change during ejaculation. The morphometric characterization was tested on nine specimens of the Lanuda breed, using a special artificial vagina. In five of the animals, a fractioning of the ejaculate was performed by taking samples every 5 min. for a total of 20 min. Air‐dried seminal smears were stained with Hemacolor and mounted permanently with Eukitt. Morphometric analysis was carried out with the morphometry module of theISAS®CASAsystem. Almost 350 cells were analysed per sample, with a total number of 3207 spermatozoa. Mean values were given as follows: length: 5.51 μm; width: 3.38 μm; area: 17.75 μm2; perimeter: 14.8 μm; ellipticity: 0.24; elongation: 0.56; rugosity: 0.87; regularity: 1.07; and shape factor: 1.41. Different animals showed differences in their morphometric values. When we compared the values from different fractions, only two samples showed differences in morphometric parameter values and four samples showed differences in shape parameters. Multivariate analysis allowed the size classification of the cells into three classes and five classes of shapes. The distribution of classes among fractions showed no differences. Despite the individual morphometric differences observed in some fractions, the characteristics of the sperm head morphometry can be considered constant along the ejaculatory period in the llama.
Public health nurses' conceptions of their role related to families with a child having attention‐deficit/hyperactivity disorder
Authors: Moen Øyfrid Larsen , Hedelin Birgitta , Hall‐Lord Marie Louise
Published: September 2013

Attention‐deficit/hyperactivity disorder is one of the most common behavioural disorders diagnosed in children. Children who have this disorder have difficulties regarding regulation of their emotions, maintaining attention and impulse control. Parents may need guidance in creating structure and predictable boundaries. One of the personnel who meet these families is the public health nurse. The aim of this study was to explore the public health nurses role in relation to these families. A qualitative explorative design with a phenomenographic approach was used. Interviews were performed with 19 nurses, six in group and one individual. In the data analyses, three descriptive categories emerged: ‘supporting the family‐unit’, which describes the nurses supervising the parents and the child in everyday challenges; ‘understanding the child’, which describes how the public health nurses use professional competence and choose the time and arena to observe the child and; ‘collaborating multidisciplinary’, which describes how the public health nurses define their own role and conceive their collaboration with other professionals. The public health nurse (PHN)'s support for the parents and the entire family is important, and the PHN is the first encounter and trustful follower throughout the course of diagnosis and care.
Type I IFN Exhaustion is a Host Defence Protecting Against Secondary Bacterial Infections
Authors: Furuya Y. , Müllbacher A.
Published: September 2013

Type I interferons (IFN‐I) have been known for decades for their indispensable role in curtailing viral infections. It is, however, now also increasingly recognized that IFN‐I is detrimental to the host in combating a number of bacterial infections. We have previously reported that viral infections induce partial lymphocyte activation, characterized by significant increases in the cell surface expression of CD69 and CD86, but not CD25. This systemic partial activation of lymphocytes, mediated by IFN‐I, is rapid and is followed by a period of IFN‐I unresponsiveness. Here we propose that IFN‐I exhaustion that occurs soon after a primary viral infection may be a host response protecting it from secondary bacterial infections.
Epigenetic Synergies Between Biotin and Folate in the Regulation of Pro‐Inflammatory Cytokines and Repeats
Authors: Xue J. , Zempleni J.
Published: September 2013

The protein biotin ligase, holocarboxylase synthetase (HLCS), is a chromatin protein that interacts physically with the DNA methyltransferase DNMT1, the methylated cytosine‐binding protein MeCP2 and the histone H3 K9‐methyltransferase EHMT1, all of which participate in folate‐dependent gene repression. Here we tested the hypothesis that biotin and folate synergize in the repression of pro‐inflammatory cytokines and long‐terminal repeats (LTRs), mediated by interactions between HLCS and other chromatin proteins. Biotin and folate supplementation could compensate for each other's deficiency in the repression of LTRs in Jurkat and U937 cells. For example, when biotin‐deficient Jurkat cells were supplemented with folate, the expression of LTRs decreased by >70%. Epigenetic synergies were more complex in the regulation of cytokines compared with LTRs. For example, the abundance of TNF‐α was 100% greater in folate‐ and biotin‐supplemented U937 cells compared with biotin‐deficient and folate‐supplemented cells. The NF‐κB inhibitor curcumin abrogated the effects of folate and biotin in cytokine regulation, suggesting that transcription factor signalling adds an extra layer of complexity to the regulation of cytokine genes by epigenetic phenomena. We conclude that biotin and folate synergize in the repression of LTRs and that these interactions are probably mediated by HLCS‐dependent epigenetic mechanisms. In contrast, synergies between biotin and folate in the regulation of cytokines need to be interpreted in the context of transcription factor signalling.
Saturated Fatty Acids Alter the Late Secretory Pathway by Modulating Membrane Properties
Authors: Payet Laurie‐Anne , Pineau Ludovic , Snyder Ellen C. R. , Colas Jenny , Moussa Ahmed , Vannier Brigitte , Bigay Joelle , Clarhaut Jonathan , Becq Frédéric , Berjeaud Jean‐Marc , Vandebrouck Clarisse , Ferreira Thierry
Published: September 2013

Saturated fatty acids (SFA) have been reported to alter organelle integrity and function in many cell types, including muscle and pancreatic β‐cells, adipocytes, hepatocytes and cardiomyocytes. SFA accumulation results in increased amounts of ceramides/sphingolipids and saturated phospholipids (PL). In this study, using a yeast‐based model that recapitulates most of the trademarks of SFA‐induced lipotoxicity in mammalian cells, we demonstrate that these lipid species act at different levels of the secretory pathway. Ceramides mostly appear to modulate the induction of the unfolded protein response and the transcription of nutrient transporters destined to the cell surface. On the other hand, saturated PL, by altering membrane properties, directly impact vesicular budding at later steps in the secretory pathway, i.e. at the trans‐Golgi Network level. They appear to do so by increasing lipid order within intracellular membranes which, in turn, alters the recruitment of loose lipid packing‐sensing proteins, required for optimal budding, to nascent vesicles. We propose that this latter general mechanism could account for the well‐documented deleterious impacts of fatty acids on the last steps of the secretory pathway in several cell types.
Characterization ofHOXgene expression in canine mammary tumour cell lines from spontaneous tumours
Authors: DeInnocentes P. , Perry A. L. , Graff E. C. , Lutful Kabir F. M. , Curtis Bird R.
Published: September 2013

Spatial/temporal controls of development are regulated by the homeotic (HOX) gene complex and require integration with oncogenes and tumour suppressors regulating cell cycle exit. Spontaneously derived neoplastic canine mammary carcinoma cell models were investigated to determine ifHOXexpression profiles were associated with neoplasia asHOXgenes promote neoplastic potential in human cancers. Comparative assessment of human and canine breast cancer expression profiles revealed remarkable similarity for all four paralogousHOXgene clusters and several unlinkedHOXgenes. Five canineHOXgenes were overexpressed with expression profiles consistent with oncogene‐like character (HOXA1,HOXA13,HOXD4,HOXD9andSIX1)and threeHOXgenes with underexpressed profiles (HOXA11,HOXC8andHOXC9) were also identified as was an apparent nonsense mutation inHOXC6. This data, as well as a comparative analysis of similar data from human breast cancers suggested expression of selectedHOXgenes in canine mammary carcinoma could be contributing to the neoplastic phenotype.
Indirect assessment of dihydropyrimidine dehydrogenase activity in cats
Authors: Saba C. F. , Schmiedt C. W. , Freeman K. G. , Edwards G. L.
Published: September 2013

Use of 5‐fluoropyridimine antimetabolite drugs, specifically 5‐fluorouracil (5‐FU), has been discouraged in cats because of adverse events including neurotoxicity and death. Causes of toxicity have never been elucidated. In humans, toxicity has been associated with ineffective metabolism secondary to deficiencies in dihydropyrimidine dehydrogenase (DPD). Direct assessment of DPD activity is challenging; determination of uracil:dihydrouracil (U:UH2) in plasma using high performance liquid chromatography (HPLC) has been reported as an indirect measurement. U:UH2 was measured in the plasma of 73 cats. Mean U:UH2 for all cats was 1.66 ± 0.11 (median 1.53, range 0.24–7.00). Seventeen (23%) cats had U:UH2 >2, a value associated with decreased DPD activity in humans. Spayed female cats had significantly lower U:UH2 as compared with intact females, and age and U:UH2 were weakly but significantly negatively correlated (r = −0.26). Studies correlating U:UH2 and 5‐FU tolerability are required to further determine the validity and use of this test in cats.
The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance
Authors: Wheeler Andrew P. S. , Ong Jonathan
Published: September 2013

In this paper, we investigate the real gas flows which occur within organic Rankine cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier–Stokes method, which uses equations of states for a variety of working fluids typical of ORC turbines, is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.
On Using Fast Response Pressure Sensors in Aerodynamic Probes to Measure Total Temperature and Entropy Generation in Turbomachinery Blade Rows
Authors: Mersinligil Mehmet , Brouckaert Jean-François , Courtiade Nicolas , Ottavy Xavier
Published: September 2013

This contribution addresses the possibility of exploiting the temperature dependency of piezoresistive sensors as a temperature measurement per se. This requires the characterization of the sensor, or the probe as a temperature probe, i.e., determination of the recovery factor between the sensor temperature and the flow temperature. This temperature calibration as well as the determination of the thermal response time was performed for two probe geometries: a high temperature flush-mounted and a low temperature subsurface mounted single sensor total pressure probe, both with a probe head diameter of 2.5 mm. Two applications are reported. The first application was performed with the flush-mounted sensor probe in the high-speed 312-stage axial compressor CREATE tested in the 2 MW test rig of LMFA at École Centrale de Lyon, in France. The probes were traversed at each inter-row section up to temperatures of 180°C and an absolute pressure of 3 bar. The second application was performed with the subsurface mounted sensor probe in the high-speed single stage R-4 compressor test rig of the von Karman Institute in Belgium. Both applications have shown results in extremely good agreement with simultaneous total temperature measurements with a Kiel-type thermocouple probe. They also underline the necessity of a very accurate temperature calibration. Finally, considering the fact that a simultaneous temperature measurement can be obtained at the same location as the pressure measurement from the sensor, it is possible to derive entropy generation after a blade row, based on the average pressure and temperature quantities. This unveils another extremely interesting aspect of using the fast response probe technique in turbomachinery applications.
Uncertainties of an Automated Optical 3D Geometry Measurement, Modeling, and Analysis Process for Mistuned Integrally Bladed Rotor Reverse Engineering
Authors: Kaszynski Alex A. , Beck Joseph A. , Brown Jeffrey M.
Published: September 2013

An automated reverse engineering process is developed that uses a structured light optical measurement system to collect dense point cloud geometry representations. The modeling process is automated through integration of software for point cloud processing, reverse engineering, solid model creation, grid generation, and structural solution. Process uncertainties are quantified on a calibration block and demonstrated on an academic transonic integrally bladed rotor. These uncertainties are propagated through physics-based models to assess impacts on predicted modal and mistuned forced response. Process details are discussed and recommendations made on reducing uncertainty. Reverse engineered parts averaged a deviation of 0.0002 in. (5 μm) which did not significantly impact low and midrange frequency responses. High frequency modes were found to be sensitive to these uncertainties demonstrating the need for future refinement of reverse engineering processes.
Air-Based Bottoming-Cycles for Water-Free Hybrid Solar Gas-Turbine Power Plants
Authors: Sandoz Raphaël , Spelling James , Laumert Björn , Fransson Torsten
Published: September 2013

A thermoeconomic model of a novel hybrid solar gas-turbine power plant with an air-based bottoming cycle has been developed, allowing its thermodynamic, economic, and environmental performance to be analyzed. Multi-objective optimization has been performed to identify the trade-offs between two conflicting objectives: minimum capital cost and minimum specific CO2 emissions. In-depth thermoeconomic analysis reveals that the additional bottoming cycle significantly reduces both the levelized cost of electricity and the environmental impact of the power plant (in terms of CO2 emissions and water consumption) when compared to a simple gas-turbine power plant without bottoming cycle. Overall, the novel concept appears to be a promising solution for sustainable power generation, especially in water-scarce areas.
An Experimental and Theoretical Investigation of Wave Propagation in Teflon and Nylon Tubing With Methods to Prevent Aliasing in Pressure Scanners
Authors: Hurst Adam M. , VanDeWeert Joe
Published: September 2013

Accurate static and dynamic pressure measurements provide the feedback needed to advance gas turbine efficiency and reliability as well as improve aircraft design and flight control. During turbine testing and aircraft flight testing, flush mounting pressure transducers at the desired pressure measurement location is not always feasible and recess mounting with connective tubing is often used as an alternative. Resonances in the connective tubing can result in aliasing within pressure scanners even within a narrow bandwidth and especially when higher frequency content dc to ∼125 Hz is desired. We present experimental results that investigate tube resonances and attenuation in 1.35 mm inner diameter (I.D.) (used on 0.063 in. tubulations) and 2.69 mm I.D. (used on 0.125 in. tubulations) Teflon and Nylon tubing at various lengths. We utilize a novel dynamic pressure generator, capable of creating large changes in air pressure (<1 psi to 10 psi, <6.8 kPa to 68.9 kPa), to determine the frequency response of such tubing from ∼1 Hz to 2800 Hz. We further compare these experimental results to established analytical models for propagation of pressure disturbances in narrow tubes. While significant theoretical and experimental work relating to the frequency response of connective tubing or transmission lines has been published, there is limited literature presenting experimental frequency response data with air as the media in elastic tubing. In addition, little progress has been made in addressing the issue of tubing-related aliasing within pressure scanners, as the low sampling rate in scanners often makes postprocessing antialiasing filters ineffective.
A Computational Study of Turbulent Airflow and Tracer Gas Diffusion in a Generic Aircraft Cabin Model
Authors: Ebrahimi Khosrow , Zheng Zhongquan C. , Hosni Mohammad H.
Published: September 2013

In order to study the capability of computational methods in investigating the mechanisms associated with disease and contaminants transmission in aircraft cabins, the computational fluid dynamics (CFD) models are used for the simulation of turbulent airflow and tracer gas diffusion in a generic aircraft cabin mockup. The CFD models are validated through the comparisons of the CFD predictions with corresponding experimental measurements. It is found that using large eddy simulation (LES) with the Werner-Wengle wall function, one can predict unsteady airflow velocity field with relatively high accuracy. However in the middle region of the cabin mockup, where the recirculation of airflow takes place, the accuracy is not as good as that in other locations. By examining different k-ε models, the current study recommends the use of the RNG k-ε model with the nonequilibrium wall function as an Reynolds averaged Navier-Stokes model for predicting the steady-state airflow velocity. It is also found that changing the nozzle height has a significant effect on the flow behavior in the middle and upper part of the cabin, while the flow pattern in the lower part is not affected as much. Through the use of LES and species transport model in simulating tracer gas diffusion, a very good agreement between predicted and measured tracer gas concentration is achieved for some monitoring locations, but the agreement level is not uniform for all the locations. The reasons for the deviations between prediction and measurement for those locations are discussed.
Effect of the Strain Rate on the Twisting of Trabecular Bone from Women with Hip Fracture
Authors: Vale Ana C. , Faustino Jennifer , Reis Luís , Lopes Ana , Vidal Bruno , Monteiro Jacinto , Fonseca João E. , Canhão Helena , Vaz Maria F.
Published: September 2013

As one of the major functions of bone is to provide structural support for the musculoskeletal system, it is important to evaluate its mechanical strength. Bones may be subjected to multiaxial stresses due to bone pathologies, accidental loads which may lead to hip, wrist fracture, or to a prosthetic joint replacement. Twist loading may lead to fractures, especially involving long bones from lower limbs. The aim of this work was to study the effect of the strain rate on the shear properties of trabecular bone samples from women with hip fracture (from 65 to 100 years). Cylindrical samples were core drilled from human femoral heads along the primary trabecular direction. The cylinder's ends were polished and embedded in blocks of polymeric material which fit the grips of the testing device. Deformation rates of 0.005, 0.01, 0.015, and 0.05 s−1 were applied. Twisting tests were conducted with or without an applied axial load of 500 N. From the torque-angular displacement curves, the shear stress–strain curves were obtained. The maximum shear strength and the shear modulus (i.e. the slope of the linear region) were determined. A large scatter of the results of the shear strength and the shear modulus was found, which is probably related to the heterogeneity of nonhealthy human bone samples. There is no significant effect of the strain rate on the maximum shear stress and the shear modulus, either in tests undertaken with or without the application of an axial load. The effect of strain rate on nonhealthy bone trabecular twisting properties did not follow the trend observed on the effect of strain rate in healthy bone, where an increase is detected.
Implementation and Validation of a 1D Fluid Model for Collapsible Channels
Authors: Anderson Peter , Fels Sidney , Green Sheldon
Published: September 2013

A 1D fluid model is implemented for the purpose of fluid-structure interaction (FSI) simulations in complex and completely collapsible geometries, particularly targeting the case of obstructive sleep apnea (OSA). The fluid mechanics are solved separately from any solid mechanics, making possible the use of a highly complex and/or black-box solver for the solid mechanics. The fluid model is temporally discretized with a second-order scheme and spatially discretized with an asymmetrical fourth-order scheme that is robust in highly uneven geometries. A completely collapsing and reopening geometry is handled smoothly using a modified area function. The numerical implementation is tested with two driven-geometry cases: (1) an inviscid analytical solution and (2) a completely closing geometry with viscous flow. Three-dimensional fluid simulations in static geometries are performed to examine the assumptions of the 1D model, and with a well-defined pressure-recovery constant the 1D model agrees well with 3D models. The model is very fast computationally, is robust, and is recommended for OSA simulations where the bulk flow pressure is primarily of interest.
On Representations for Joint Moments Using a Joint Coordinate System
Authors: O'Reilly Oliver M. , Sena Mark P. , Feeley Brian T. , Lotz Jeffrey C.
Published: September 2013

In studies of the biomechanics of joints, the representation of moments using the joint coordinate system has been discussed by several authors. The primary purpose of this technical brief is to emphasize that there are two distinct, albeit related, representations for moment vectors using the joint coordinate system. These distinct representations are illuminated by exploring connections between the Euler and dual Euler bases, the “nonorthogonal projections” presented in a recent paper by Desroches et al. (2010, “Expression of Joint Moment in the Joint Coordinate System,” ASME J. Biomech. Eng., 132(11), p. 11450) and seminal works by Grood and Suntay (Grood and Suntay, 1983, “A Joint Coordinate System for the Clinical Description of Three-Dimensional Motions: Application to the Knee,” ASME J. Biomech. Eng., 105(2), pp. 136–144) and Fujie et al. (1996, “Forces and Moment in Six-DOF at the Human Knee Joint: Mathematical Description for Control,” Journal of Biomechanics, 29(12), pp. 1577–1585) on the knee joint. It is also shown how the representation using the dual Euler basis leads to straightforward definition of joint stiffnesses.
The Role of Finite Displacements in Vocal Fold Modeling
Authors: Chang Siyuan , Tian Fang-Bao , Luo Haoxiang , Doyle James F. , Rousseau Bernard
Published: September 2013

Human vocal folds experience flow-induced vibrations during phonation. In previous computational models, the vocal fold dynamics has been treated with linear elasticity theory in which both the strain and the displacement of the tissue are assumed to be infinitesimal (referred to as model I). The effect of the nonlinear strain, or geometric nonlinearity, caused by finite displacements is yet not clear. In this work, a two-dimensional model is used to study the effect of geometric nonlinearity (referred to as model II) on the vocal fold and the airflow. The result shows that even though the deformation is under 1 mm, i.e., less than 10% of the size of the vocal fold, the geometric nonlinear effect is still significant. Specifically, model I underpredicts the gap width, the flow rate, and the impact stress on the medial surfaces as compared to model II. The study further shows that the differences are caused by the contact mechanics and, more importantly, the fluid-structure interaction that magnifies the error from the small-displacement assumption. The results suggest that using the large-displacement formulation in a computational model would be more appropriate for accurate simulations of the vocal fold dynamics.
Nanoparticle Mass Transfer From Lung Airways to Systemic Regions—Part I: Whole-Lung Aerosol Dynamics
Authors: Kolanjiyil Arun V. , Kleinstreuer Clement
Published: September 2013

This is a two-part paper describing inhaled nanoparticle (NP) transport and deposition in a model of a human respiratory tract (Part I) as well as NP-mass transfer across barriers into systemic regions (Part II). Specifically, combining high-resolution computer simulation results of inhaled NP deposition in the human airways (Part I) with a multicompartmental model for NP-mass transfer (Part II) allows for the prediction of temporal NP accumulation in the blood and lymphatic systems as well as in organs. An understanding of nanoparticle transport and deposition in human respiratory airways is of great importance, as exposure to nanomaterial has been found to cause serious lung diseases, while the use of nanodrugs may have superior therapeutic effects. In Part I, the fluid-particle dynamics of a dilute NP suspension was simulated for the entire respiratory tract, assuming steady inhalation and planar airways. Thus, a realistic airway configuration was considered from nose/mouth to generation 3, and then an idealized triple-bifurcation unit was repeated in series and parallel to cover the remaining generations. Using the current model, the deposition of NPs in distinct regions of the lung, namely extrathoracic, bronchial, bronchiolar, and alveolar, was calculated. The region-specific NP-deposition results for the human lung model were used in Part II to determine the multicompartmental model parameters from experimental retention and clearance data in human lungs. The quantitative, experimentally validated results are useful in diverse fields, such as toxicology for exposure-risk analysis of ubiquitous nanomaterial as well as in pharmacology for nanodrug development and targeting.
Effects of Cyclic Motion on Coronary Blood Flow
Authors: Hasan Mahmudul , Rubenstein David A. , Yin Wei
Published: September 2013

The goal of this study was to establish a computational fluid dynamics model to investigate the effect of cyclic motion (i.e., bending and stretching) on coronary blood flow. The three-dimensional (3D) geometry of a 50-mm section of the left anterior descending artery (normal or with a 60% stenosis) was constructed based on anatomical studies. To describe the bending motion of the blood vessel wall, arbitrary Lagrangian–Eularian methods were used. To simulate artery bending and blood pressure change induced stretching, the arterial wall was modeled as an anisotropic nonlinear elastic solid using the five-parameter Mooney–Rivlin hyperelastic model. Employing a laminar model, the flow field was solved using the continuity equations and Navier–Stokes equations. Blood was modeled as an incompressible Newtonian fluid. A fluid–structure interaction approach was used to couple the fluid domain and the solid domain iteratively, allowing force and total mesh displacement to be transferred between the two domains. The results demonstrated that even though the bending motion of the coronary artery could significantly affect blood cell trajectory, it had little effect on flow parameters, i.e., blood flow velocity, blood shear stress, and wall shear stress. The shape of the stenosis (asymmetric or symmetric) hardly affected flow parameters either. However, wall normal stresses (axial, circumferential, and radial stress) can be greatly affected by the blood vessel wall motion. The axial wall stress was significantly higher than the circumferential and radial stresses, as well as wall shear stress. Therefore, investigation on effects of wall stress on blood vessel wall cellular functions may help us better understand the mechanism of mechanical stress induced cardiovascular disease.
Mathematical Modeling for Screw Rotor Form Grinding on Vertical Multi-Axis Computerized Numerical Control Form Grinder
Authors: Wu Yu-Ren , Fan Chung-Wen
Published: September 2013

The pair of screw rotors is a key element of a twin-screw compressor, and rotor tooth modification has gradually received attention because it can reduce operating compressor noise. Current rotor machining references are mainly related to forming tool design or abrasion of the “horizontal” grinder, but little attention has been paid to form grinding using a “vertical” grinder and simulating the machining flexibility of each grinder axis. Therefore, this paper established a general coordinate system for the screw rotor form grinding and connected it to a vertical five-axis computerized numerical control form grinder to simulate rotor grinding and tooth modification. Further, the influence of a form grinding wheel contour designed by different declination angles of a rotor tooth profile on a grinding rotor tooth and the influence of the motion parameter of each axis on the machining precision of the rotor and the tooth shape are proposed in this paper.
Identification of Johnson–Cook and Tresca's Parameters for Numerical Modeling of AISI-304 Machining Processes
Authors: Bosetti Paolo , Maximiliano Giorgio Bort Carlos , Bruschi Stefania
Published: September 2013

This paper presents a procedure for the identification of Johnson Cook model parameters and Tresca's law friction factor for orthogonal cutting of AISI 304. The process is described by a thermomechanical numerical model. The parameters are identified by minimizing the error in the prediction of cutting force, chip thickness, and chip curvature. Two optimization algorithms where tested: a pure Nelder–Mead method (NMM), and a hybrid procedure, in which the starting simplex for NMM is calculated by means of a genetic algorithm. The results emphasize the importance of the initial guess chosen in the optimization to obtain a reliable set of parameters. By using the optimized parameters in the numerical model, the cutting force, the chip thickness, and the chip curvature can be evaluated with an acceptable accuracy. The identified rheological and tribological coefficients are validated for different orthogonal cutting conditions.
A Coupling Method for Hydrodynamic Ram Analysis: Experimental and Numerical Investigation
Authors: Mhamed Souli , Jonathan Gabrys
Published: September 2013

Hydrodynamic pressures generated by a nonexploding projectile penetrating a fuel tank can be very destructive. During the impact, the projectile transfers momentum and kinetic energy to the container through the surrounding fluid. In aerospace industry, hydrodynamic ram effects are identified as an important factor for aircraft vulnerability because fuel tank of the aircraft is the most vulnerable component because the tank represents the largest exposed area to outside projectiles. Understanding the magnitude of the pressure and its distribution inside the tank is critical for designing the structure to survive these incidents. Numerical simulation when validated by tests data is an efficient tool to investigate mechanical phenomena of hydrodynamic ram effects and its damage on the surrounding structure. The main numerical difficulties that can be encountered in this kind of problems and in general penetration problems is the high mesh distortion of the fluid at the fluid–structure interface during projectile penetration. To prevent high mesh distortion of the fluid, a coupling method is used for the fluid as well as a new coupling algorithm is performed at the fluid–structure interface. The coupling method used in the paper has been developed with the collaboration of the first author in the ls-dyna code and validated for several applications in automotive and aerospace industry for fuel sloshing tank and bird impact problems. In this paper, experimental investigation has been performed and predicted pressure is compared with measured pressure for validation. In addition, modeling parameters such as element size and coupling parameters for the fluid structure coupling are investigated. The purpose of the research is to demonstrate the capability and potential of the fluid structure interaction for simulating this type of problems. Different ways to model reflections of pressure waves off the sidewalls are studied as well. Good correlation is achieved for pressure at specific location inside the water tank.
Attenuation Effects of a Single Deck Floating Roof in a Liquid Storage Tank
Authors: Ali Goudarzi Mohammad
Published: September 2013

Liquid-roof interaction imposes a complicated distribution of out-of-plane deformation on the single-deck type floating roof (SDRF), which is the main source of considerable seismic stresses in floating roof. In this paper, an analytical solution for evaluating the dynamic interaction between the liquid and the floating roof is developed. Main physical and geometrical parameters are involved by the proposed analytical solution (PAS) for evaluating the seismic stresses of a single deck floating roof tanks (SDFR). The results of PAS are compared with the results of existing empirical formulas for various dimensions of SDRF tanks. In order to assess the validity of PAS for various sloshing wave height, a numerical model based on finite element method is established and the PAS results are compared with the finite element method (FEM) analysis results. The PAS predictions are in very good agreement with both the available empirical formula and the numerical model results.
Experience With Gas Path Analysis for On-Wing Turbofan Condition Monitoring
Authors: Verbist Michel L. , Visser Wilfried P. J. , van Buijtenen Jos P.
Published: September 2013

Gas path analysis (GPA) is an effective method for determination of turbofan component condition from measured performance parameters. GPA is widely applied on engine test rig data to isolate components responsible for performance problems, thereby offering substantial cost saving potential. Additional benefits can be obtained from the application of GPA to on-wing engine data. This paper describes the experience with model-based GPA on large volumes of on-wing measured performance data. Critical is the minimization of the GPA results uncertainty in order to maintain reliable diagnostics and condition monitoring information. This is especially challenging given the variable in-flight operating conditions and limited on-wing sensor accuracy. The uncertainty effects can be mitigated by statistical analysis and filtering and postprocessing of the large datasets. By analyzing correlations between measured performance data trends and estimated component condition trends errors can be isolated from the GPA results. The various methods assessed are described and results are demonstrated in a number of case studies on a large turbofan engine fleet.
Prediction of Mechanical Power Loss of Planet Gear Roller Bearings Under Combined Radial and Moment Loading
Authors: Talbot D. , Li S. , Kahraman A.
Published: September 2013

A modeling methodology is proposed to predict load-dependent (mechanical) power loss of cylindrical roller bearings under combined radial and moment loading with focus on planetary gear set planet bearings. This methodology relies on two models. The first model is a bearing load distribution model to predict load intensities along rolling element contacts due to combined force–moment loading. This model takes into account planet bearing macrogeometry as well as micromodifications to the roller and race surfaces. The second model is an elastohydrodynamic lubrication (EHL) model employed to predict rolling power losses of bearing contacts with load intensities predicted by the load distribution model. The bearing mechanical power loss methodology is applied to bearings of an automotive planetary gear set to quantify the sensitivity of mechanical power loss to key bearing, lubrication and surface parameters as well as operating speed, load and temperature conditions.
Adaptive LQR-Control Design and Friction Compensation for Flexible High-Speed Rack Feeders
Authors: Schindele Dominik , Aschemann Harald
Published: September 2013

Rack feeders for the automated operation of high bay rackings are of high practical importance. They are characterized by a horizontally movable carriage supporting a tall and flexible vertical beam structure, on which a cage containing the payload can be positioned in vertical direction. To shorten the transport times by using trajectories with increased maximum acceleration and jerk values, accompanying control measures can be introduced counteracting or avoiding undesired vibrations of the flexible structure. In this contribution, both the control-oriented modeling for an experimental setup of such a flexible rack feeder and the model-based design of a gain-scheduled feedforward and feedback control structure are presented. Whereas, a kinematical model is sufficient for the vertical axis, the horizontal motion of the rack feeder is modeled as a planar elastic multibody system with the cage position as scheduling parameter. For the mathematical description of the bending deflections, a one-dimensional Ritz ansatz is introduced. The tracking control design is performed separately for both the horizontal and the vertical axes using decentralized state-space representations. Remaining model uncertainties are estimated by a disturbance observer. The resulting tracking accuracy of the proposed control concept is shown by measurement results from the experimental setup. Furthermore, these results are compared to those obtained with an alternative control concept from previous work.
Fluid-Conveying Flexible Pipes Modeled by Large-Deflection Finite Elements in Multibody Systems
Authors: Meijaard J. P.
Published: September 2013

The modeling and simulation of flexible multibody systems containing fluid-conveying pipes are considered. It is assumed that the mass-flow rate is prescribed and constant and the pipe cross section is piecewise uniform. An existing beam element capable of handling large motions is modified to include the effect of the fluid flow and the initial curvature of the pipe. The modified element is incorporated in a finite-element based multibody system dynamics program, which takes care of the connection with other parts of the system and the simulation. The element is applied in several test problems: the buckling of a simply supported pipe, the flutter instability of a cantilever pipe, and the motion of a curved pipe that can rotate about an axis perpendicular to its plane. As a three-dimensional example, a Coriolis mass-flow rate meter with a U-shaped pipe is considered.
Review on Cell Mechanics: Experimental and Modeling Approaches
Authors: Rodriguez Marita L. , McGarry Patrick J. , Sniadecki Nathan J.
Published: September 2013

The interplay between the mechanical properties of cells and the forces that they produce internally or that are externally applied to them play an important role in maintaining the normal function of cells. These forces also have a significant effect on the progression of mechanically related diseases. To study the mechanics of cells, a wide variety of tools have been adapted from the physical sciences. These tools have helped to elucidate the mechanical properties of cells, the nature of cellular forces, and mechanoresponses that cells have to external forces, i.e., mechanotransduction. Information gained from these studies has been utilized in computational models that address cell mechanics as a collection of biomechanical and biochemical processes. These models have been advantageous in explaining experimental observations by providing a framework of underlying cellular mechanisms. They have also enabled predictive, in silico studies, which would otherwise be difficult or impossible to perform with current experimental approaches. In this review, we discuss these novel, experimental approaches and accompanying computational models. We also outline future directions to advance the field of cell mechanics. In particular, we devote our attention to the use of microposts for experiments with cells and a bio-chemical-mechanical model for capturing their unique mechanobiological properties.
Influence of Burner Material, Tip Temperature, and Geometrical Flame Configuration on Flashback Propensity of H2-Air Jet Flames
Authors: Duan Zhixuan , Shaffer Brendan , McDonell Vincent , Baumgartner Georg , Sattelmayer Thomas
Published: September 2013

Flashback is a key operability issue for low emission premixed combustion systems operated on high hydrogen content fuels. Previous work investigated fuel composition impacts on flashback propensity and found that burner tip temperature was important in correlating flashback data in premixed jet flames. An enclosure around the jet flame was found to enhance the flame–burner rim interaction. The present study further addresses these issues using a jet burner with various geometric configurations and interchangeable materials. Systematic studies addressing the quantitative influence of various parameters such as tip temperature, burner material, enclosure size, and burner diameter on flashback propensity were carried out. A comprehensive overview of the flashback limits for all conditions tested in the current study as well as those published previously is given. The collective results indicate that the burner materials, tip temperature, and flame confinement play significant roles for flashback propensity and thus help explain previous scatter in flashback data. Furthermore, the present work indicates that the upstream flame propagation during flashback is affected by the burner material. The material with lower thermal conductivity yields larger flashback propensity but slower flame regression inside the tube. These observations can be potentially exploited to minimize the negative impacts of flashback in practical applications.