bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical and virological features of occult hepatitis B in patients with HBsAg seroclearance post‐treatment or spontaneously
Authors: Cheng Huei‐Ru , Kao Jia‐Horng , Wu Hui‐Lin , Chen Ting‐Chih , Tseng Tai‐Chung , Liu Chen‐Hua , Su Tung‐Hung , Chen Pei‐Jer , Chen Ding‐Shinn , Liu Chun‐Jen
Published: September 2013

Background

Occult hepatitis B virus (HBV) infection (OHB) may exist in patients experiencing hepatitis B surface antigen (HBsAg) seroclearance.

Aims

We examined the clinical and virological features of OHB in patients who lost HBsAg post‐treatment or spontaneously.

Methods

We collected 44 patients with HBsAg seroclearance: 15 patients with dual HBV/hepatitis C virus (HCV) infection who lost HBsAg after peginterferon alfa‐2a (PEG‐IFN) plus ribavirin therapy; 13 HBV mono‐infected patients who lost HBsAg after various oral antiviral therapies; and 16 patients who lost HBsAg spontaneously. OHB was defined as detectable serum HBV DNA in the absence of HBsAg. Viral mutations associated with OHB were identified by comparison with matched controls that remained positive for HBsAg, and further characterized in vitro.

Results

The prevalence of OHB was 34.1% (15/44) in all patients, which was not significantly different among three groups. One mutation in surface promoter/polymerase region, C3050T (preS1T68I), was identified to be associated with the seroclearance of HBsAg in six cases. This mutation does not change the amino acid sequence of the polymerase protein. The S promoter activity was significantly lower in the construct containing C3050T mutation as compared with the wild‐type (P = 0.0008). However, this mutation did not affect HBV replication, transcription and translation in the context of the full‐length HBV genome. OHB was not rare in patients with HBsAg seroclearance.

Conclusions

One mutation, C3050T (preS1T68I), decreased S promoter activity; nevertheless, other factors may play more important role in the clearance of HBsAg in these OHB patients.
Conophylline suppresses hepatic stellate cells and attenuates thioacetamide‐induced liver fibrosis in rats
Authors: Kubo Norio , Saito Rie , Hamano Kunihisa , Nagasawa Masahiro , Aoki Fumiaki , Takei Izumi , Umezawa Kazuo , Kuwano Hiroyuki , Kojima Itaru
Published: September 2013

Background & Aims

Conophylline (CnP) is a vinca alkaloid purified from a tropical plant and inhibits activation of pancreatic stellate cells. We investigated the effect of CnP on hepatic stellate cells (HSC) in vitro. We also examined whether CnP attenuates hepatic fibrosis in vivo.

Method

We examined the effect of CnP on the expression of α‐smooth muscle actin (α‐SMA) and collagen‐1, DNA synthesis and apoptosis in rat HSC and Lx‐2 cells. We also examined the effect of CnP on hepatic fibrosis induced by thioacetamide (TAA).

Results

In rat HSC and Lx‐2 cells, CnP reduced the expression of α‐SMA and collagen‐1. CnP inhibited DNA synthesis induced by serum. CnP also promoted activation of caspase‐3 and induced apoptosis as assessed by DNA ladder formation and TUNEL assay. In contrast, CnP did not induce apoptosis in AML12 cells. We then examined the effect of CnP on TAA‐induced cirrhosis. In TAA‐treated rats, the surface of the liver was irregular and multiple nodules were observed. Histologically, formation of pseudolobules surrounded by massive fibrous tissues was observed. When CnP was administered together with TAA, the surface of the liver was smooth and liver fibrosis was markedly inhibited. Collagen content was significantly reduced in CnP‐treated liver.

Conclusion

Conophylline suppresses HSC and induces apoptosis in vitro. CnP also attenuates formation of the liver fibrosis induced by TAA in vivo.
Panaxatriol saponin ameliorated liver injury by acetaminophen via restoring thioredoxin‐1 and pro‐caspase‐12
Authors: Wang Shengdong , Wang Xiao , Luo Fucheng , Tang Xiaodan , Li Kui , Hu Xiaomei , Bai Jie
Published: September 2013

Background & Aims

Acetaminophen (APAP) is widely used as an antipyretic agent which is safe at therapeutic doses. However, overdose of APAP induces fatal and non‐fatal hepatic necroses. The chemical reactive metabolites of APAP initiate toxicity and inflammatory response within the liver and lead to acute liver failure. However, the mechanism underlying APAP‐induced liver injury is unknown. Thioredoxin‐1 (TRX‐1) is an important redox regulator, which plays roles in resisting oxidative stress, regulating inflammation and inhibiting apoptosis. Panaxatriol saponin (PTS) is one of the biologically active fractions of Panax notoginseng which is a traditional Chinese medicine. The aim of this study was to investigate the mechanism on PTS protecting liver from APAP hepatotoxicity.

Methods

Mice were divided into three groups, control group, APAP group and APAP combined with PTS group. Alanine aminotransferase (ALT) and tumour necrosis factor‐alpha (TNF‐α) were detected by ELISA. TRX‐1 and pro‐caspase‐12 were examined by Western blotting.

Results

Our results showed PTS inhibited the levels of ALT and TNF‐α by APAP. Pretreatment with PTS ameliorated liver injury induced by APAP. The decrease in TRX‐1 expression was restored by PTS, as well as decreased pro‐caspase‐12 expression was inhibited by PTS. These data suggest that PTS has roles in suppressing the hepatotoxicity by APAP.

Conclusion

Panaxatriol saponin ameliorated liver injury by APAP through restoring the expression TRX‐1 and inhibiting pro‐caspase‐12 decrease.
Similarity in temporal variation in sex‐biased dispersal over short and long distances in the dark‐eyed junco,Junco hyemalis
Authors: Liebgold Eric B. , Gerlach Nicole M. , Ketterson Ellen D.
Published: September 2013

Patterns of sex‐biased dispersal (SBD) are typically consistent within taxa, for example female‐biased in birds and male‐biased in mammals, leading to theories about the evolutionary pressures that lead to SBD. However, generalizations about the evolution of sex biases tend to overlook that dispersal is mediated by ecological factors that vary over time. We examined potential temporal variation in between‐ and within‐population dispersal over an 11‐year period in a bird, the dark‐eyed junco (Junco hyemalis). We measured between‐population dispersal patterns using genetic assignment indices and found yearly variation in which sex was more likely to have immigrated. When we measured within‐population spatial genetic structure and mark–recapture dispersal distances, we typically found yearly SBD patterns that mirrored between‐population dispersal, indicating common eco‐evolutionary causes despite expected differences due to the scale of dispersal. However, in years without detectable between‐population sex biases, we found genetic similarity between nearby males within our population. This suggests that, in certain circumstances, ecological pressures may act on within‐population dispersal without affecting dispersal between populations. Alternatively, current analytical tools may be better able to detect within‐population SBD. Future work will investigate potential causes of the observed temporal variation in dispersal patterns and whether they have greater effects on within‐population dispersal.
A Note on Credit Allocation, Income Distribution and the Circuit of Capital
Authors: dos Santos Paulo L.
Published: September 2013

This note considers the relationship between credit allocation and the class distribution of income in the Circuit of Capital. Production and consumption credit inject means of purchase into different phases of capitalist reproduction. Comparative‐dynamic analysis of steady‐state evolutions shows that in the dynamic terms of Circuit of Capital production and consumption credit respectively increase wage and profit shares of aggregate income. These findings hold more broadly for any setting where sectoral revenue elasticities of outlays are below unity. They also have direct policy relevance for advanced and middle‐income economies where household borrowing has been encouraged in attempts to support demand and growth.
Formation of Thermal Coagulum on Multielectrode Catheters during Phased Radiofrequency Energy Ablation of Persistent Atrial Fibrillation
Authors: DEBRUYNE PHILIPPE , ROSSENBACKER TOM , VANKELECOM BART , CHARLIER FILIP , ROOSEN JOHN , ECTOR BAVO , JANSSENS LUC
Published: September 2013

Background

Radiofrequency ablation (RFA) can unfavorably cause coagulum on the ablation electrode. The aim of this study was to assess this phenomenon on three different multielectrode catheters used to treat persistent atrial fibrillation with duty‐cycled RFA.

Methods and results

Twenty‐six consecutive patients have been treated with the pulmonary vein ablation catheter (PVAC) and the multiarray ablation catheter (MAAC). In 13 patients, additional ablation with the multiarray septal catheter (MASC) has been performed. The multichannel RF generator GENius™ (Medtronic Inc., Minneapolis, MN, USA) independently delivered energy in a bipolar and unipolar mode (ratio of 4/1, 2/1, or 1/1) to any of the electrodes. Versions 14.2, 14.3, and 14.4 of the generator were used. Coagulum presence was determined postablation by careful visual inspection of the catheter electrodes. No coagulum formation was visualized on the PVACs. Coagulum formation was visualized in 59% of the electrodes of the MAACs using a 2/1 mode and the 14.2 software version versus 69% using the 14.4 version and a 2/1 mode (P = 0.7) versus 14% of the electrodes applying a 1/1 ratio and the 14.4 software version (P < 0.001).

Conclusions

Duty‐cycled RFA in 2/1 bipolar/unipolar ratio generates a substantial frequency of coagulum formation on the multielectrode catheters MAAC and MASC. The use of the 14.4 version of the software to drive the RF generator and the use of energy in the default 1/1 bipolar/unipolar ratio could significantly reduce the frequency of coagulum formation, but so far, could not completely overcome it. The PVAC did not form coagulum, regardless of generator version or energy ratio used.
The tubarium construction of Lower Ordovician (Dapingian) Baltograptus species (Graptolithina) from Dalarna, Sweden
Authors: Maletz Jörg , Slovacek Mariah
Published: September 2013

Isolated and chemically bleached graptolite specimens of Baltograptus from Skattungbyn, Dalarna (central Sweden), reveal important new information on the internal construction of the tubarium. The specimens show the typical metasicular origin of th11 and the presence of numerous longitudinal rods in the prosicula. The investigation provides some insight into intraspecific variation and on the differentiation of individual species. It also provides information on the early evolution of the two‐stiped dichograptids. Three distinct species, identified as Baltograptus minutus (Törnquist) B. kurcki (Törnquist) and B. extremus sp. nov. can be recognized in the collection of hundreds of specimens. The Baltograptus species are associated with a diverse Dapingian graptolite fauna, prepared by Roland Skoglund, but never investigated in detail, including specimens of Pseudophyllograptus densus, Acrograptus gracilis and other taxonomically and biostratigraphically important taxa.
Skill Composition, Fertility, and Economic Growth
Authors: Day Creina
Published: September 2013

While high fertility persists in the poorest countries and fertility declines with per capita income in developing countries, fertility and per capita income are now positively associated across most developed countries. This paper presents a model where a U‐shaped relationship between overall fertility and per capita income reflects within country differences in workforce skill composition and household choice of occupation, fertility, and childrearing. The fraction of skilled workers rises with economic growth. By allowing for both differences in the fertility of skilled and unskilled workers and purchased childrearing inputs, we explain a poverty trap with high fertility, fertility decline with economic development, and the possible reversal of fertility decline in a developed economy where most workers are skilled.
Elite Colleges and Socioeconomic Status
Authors: Lee Elizabeth M.
Published: September 2013

Elite colleges have long been associated with socioeconomic reproduction, passing along elite social standing to children of middle and upper‐middle socioeconomic status (SES) parents. How has that role changed during the expansion of American higher education over the past 50 years? Have elite colleges and universities also become providers of socioeconomic mobility? In this essay, I outline recent demographic, admissions, and financial aid changes at these institutions and compare both in‐college experiences and college outcomes between low‐SES and more‐affluent students at elite colleges. I argue that although elite colleges and universities do include greater numbers of low‐SES students than in earlier generations and have great potential for even further inclusion, they remain far from serving as broad engines of socioeconomic mobility.
Limited Nomination Reliability Using Single‐ and Multiple‐item Measures
Authors: Babcock Ben , Marks Peter E. L. , Crick Nicki R. , Cillessen Antonius H. N.
Published: September 2013

This article examines a variety of reliability issues as related to limited nomination sociometric measures. Peer nomination data were collected from 77 sixth grade classrooms. Results showed that, although some single‐item peer nomination measures were relatively reliable, many single‐item peer nomination measures using limited nominations were quite unreliable. Overt aggression nomination items were the only set of single‐item measures where mean classroom reliability estimates were .75 or greater. Combining multiple items led to substantially better reliability, as combining the two least reliable items for a category into a single measure made the composite more reliable than the most reliable single measure. Having more nominators in the sample also increased reliability. The limited nomination items overall tended to be less reliable than similar unlimited nomination items from other studies. The authors end with recommendations for obtaining the most reliable peer nomination data possible from a study.
New RHCE variant alleles encoding the D– – phenotype
Authors: Ochoa‐Garay Gorka , Moulds Joann M. , Cote Jacqueline , Kresie Lesley , Garaizar Adirane , Goldman Mindy , Wynn Polly
Published: September 2013

Background

Variant alleles that do not produce RhCE antigens are rare. Consequently, they pose a challenge to transfusion when found in alloimmunized patients and make blood units valuable when found in donors.

Study Design and Methods

Five index cases and their relatives were studied by both serologic and molecular techniques. Genomic DNA was subjected to microarray genotyping, sequencing, exon scanning, and/or copy number determination assays to identify the RHCE allele(s) responsible for their D+ C− c− E– e− (D– –) phenotype.

Results

The five apparent D– – phenotypes were confirmed by molecular methods. Three of them contained unreported RHCE‐null alleles, namely, RHCE*Ce‐D(3‐9)‐Ce, RHCE*Ce87_93insT, and RHCE*cE221A.

Conclusion

Molecular analysis of D– – phenotypes allows the identification of new RHCE‐null variants. Conversely, detection of described RHCE‐null variants facilitates confirmation of D– – phenotypes in patients and donors, helping improve transfusion safety.
Local Heat Transfer Dependency on Thermal Boundary Condition in Ribbed Cooling Channel Geometries
Authors: Cukurel Beni , Arts Tony
Published: September 2013

The present study is geared toward quantifying the effects of imposed thermal boundary condition in cooling channel applications. In this regard, tests are conducted in a generic passage, with evenly distributed rib type perturbators at 90 deg, with a 30% passage blockage ratio and pitch-to-height ratio of 10. Uniform heat-flux is imposed on the external side of the slab which provides Biot number and solid-to-fluid thermal conductivity ratio around 1 and 600, respectively. Through infrared thermometry measurements over the wetted surface and via an energy balance within the solid, conjugate heat transfer coefficients are calculated over a single rib-pitch. The local heat extraction is demonstrated to be a strong function of the conduction effects, observed more dominantly in the rib vicinity. Moreover, the aero-thermal effects are investigated by comparing the findings with analogous aerodynamic literature, enabling heat transfer distributions to be associated with distinct flow structures. Furthermore, the results are contrasted with the iso-heat-flux wetted boundary condition test case. Neglecting the thermal boundary condition dependence, and thus the true thermal history of the boundary layer, is demonstrated to produce large errors in heat transfer predictions.
Temperature Dependent Viscosity and Thermal Conductivity Effects on the Laminar Forced Convection in Straight Microchannels
Authors: Del Giudice Stefano , Savino Stefano , Nonino Carlo
Published: September 2013

A parametric investigation is carried out on the effects of temperature dependent viscosity and thermal conductivity and of viscous dissipation in simultaneously developing laminar flows of liquids in straight microchannels of constant cross sections. Uniform heat flux boundary conditions are specified at the heated walls. A superposition method is proved to be applicable in order to predict the value of the Nusselt number by considering separately the effects of temperature dependent viscosity and those of temperature dependent thermal conductivity. In addition, it is found that the influence of the temperature dependence of thermal conductivity on the value of the Nusselt number is independent of the value of the Brinkman number, i.e., it is the same no matter whether viscous dissipation is negligible or not. Finally, it is demonstrated that, in liquid flows, the main effects on pressure drop of temperature dependent fluid properties can be retained even if only viscosity is allowed to vary with temperature, the other properties being assumed constant. Viscosity is assumed to vary with temperature according to an exponential relation, while a linear dependence of thermal conductivity on temperature is assumed. The other fluid properties are held constant. Two different cross-sectional geometries are considered, corresponding to both axisymmetric (circular) and three-dimensional (square) microchannel geometries. A finite element procedure is employed for the solution of the parabolized momentum and energy equations. Computed axial distributions of the local Nusselt number and of the apparent Fanning friction factor are presented for different values of the viscosity and thermal conductivity Pearson numbers and of the Brinkman number.
Numerical Investigation of Microflow Over Rough Surfaces: Coupling Approach
Authors: Rovenskaya Olga , Croce Giulio
Published: September 2013

A numerical analysis of the flow field in rough microchannel is carried out decomposing the computational physical domain into kinetic and continuum subdomains. Each domain size is determined by the value of a proper threshold parameter, based on the local Knudsen number and local gradients of macroparameters. This switching parameter is computed from a preliminary Navier–Stokes (NS) solution throughout the whole physical domain. The solution is then advanced in time simultaneously in both kinetic and continuum domains: The coupling is achieved by matching half fluxes at the interface of the kinetic and Navier–Stokes domains, taking care of the conservation of momentum, energy, and mass through the interface. The roughness geometry is modeled as a series of triangular obstructions with a relative roughness up to a maximum of 5% of the channel height. A wide range of Mach numbers is considered, from nearly incompressible to chocked flow conditions 0.001 ≤ Ma ≤ 0.75 and a Reynolds number up to 170. To estimate rarefaction effect, the flow at Knudsen number ranging from 0.01 to 0.08 and fixed pressure ratio has been considered. Accuracy and discrepancies between full Navier–Stokes, kinetic, and coupled solutions are discussed, assessing the range of applicability of first order slip condition in rough geometries. The effect of the roughness is discussed via Poiseuille number as a function of local Knudsen and Mach numbers.
Numerical Simulations of Hydrodynamics and Heat Transfer in Wavy Falling Liquid Films on Vertical and Inclined Walls
Authors: Yu Hongyi , Gambaryan-Roisman Tatiana , Stephan Peter
Published: September 2013

The flow of thin falling liquid films is unstable to long-wave disturbances. The flow instability leads to development of waves at the liquid–gas interface. The effect of the waves on heat and mass transfer in falling liquid films is a subject of ongoing scientific discussion. In this work, numerical investigation of the wave dynamics has been performed using a modified volume-of-fluid (VOF) method for tracking the free surface. The surface tension is described using the continuum surface force (CSF) model. With low disturbance frequency, solitary waves of large amplitude are developed, which are preceded by low-amplitude capillary waves. With high disturbance frequency, low amplitude sinusoidal waves are developed. The waveforms dependent on the Reynolds number and disturbance frequency are summarized in a form of a regime map. A correlation describing the separation curve between the sinusoidal waves regime and solitary waves regime is proposed. The wave parameters (peak height, length, and propagation speed) are computed from the simulation results and compared with available experimental correlations in a wide range of parameters. The effects of the disturbance frequency and the plane inclination angle on the wave dynamics have been studied. The interaction of waves initiated by simultaneous disturbances of two different frequencies has been investigated. The heat transfer in the wavy film has been simulated for the constant wall temperature boundary condition. The effects of Prandtl number and disturbance frequency on local and global heat transfer parameters have been investigated. It has been shown that the influence of waves on heat transfer is significant for large Prandtl numbers in a specific range of disturbance frequencies.
Uniform Solution on the Combined Effect of Magnetic Field and Internal Heat Generation on Rayleigh–Bénard Convection in Micropolar Fluid
Authors: Khalid I. K. , Mokhtar N. F. M. , Arifin N. M.
Published: September 2013

Combined effect of magnetic field and internal heat generation on the onset of Rayleigh–Bénard convection in a horizontal micropolar fluid layer is studied. The bounding surfaces of the liquids are considered to be rigid-free, rigid-rigid, and free-free with combination isothermal on the spin-vanishing boundaries. A linear stability analysis is used and the Galerkin method is employed to find the critical stability parameters numerically. The influence of various parameters on the onset of convection has been analyzed. It is shown that the presence of magnetic field always has a stability effect on the Rayleigh–Bénard convection in micropolar fluid.
Systematic Ideation Effectiveness Study of TRIZ
Authors: Hernandez Noe Vargas , Schmidt Linda C. , Okudan Gül E.
Published: September 2013

The objective of this paper is to present experimental results of a specific ideation method TRIZ (an abbreviation of a Russian acronym of “Teoriya Resheniya Izobretatelskikh Zadatch” meaning theory of inventive problem solving) as compared to ad hoc methods used by students. It is critical to understand how and why TRIZ works as it can lead to improvements on how to teach this method, and also how to analyze ideation methods in general. Our hypothesis is that TRIZ improves the creativity level of subjects using it as observed in the produced design outcomes. The experiments were conducted simultaneously at two institutions: University of Texas at El Paso (UTEP) and University of Maryland (UMD). The results were analyzed as part of an existing research partnership with Pennsylvania State University (PSU). The ideation task present here has been used in all three institutions; it is the redesign of a traffic light that uses light-emitting diodes (LED) instead of incandescent bulbs leading to snow build-up on the lights in certain climates as LED's generate less heat to melt the snow. UTEP and UMD student groups were tasked with redesigning the LED traffic lights to resolve this issue. The assessment was performed on the outcome (i.e., ideas generated) using quantity, novelty and variety as metrics. Numerical results of these metrics are shown along with conclusions based on observations of the experimental process. Data presented in this paper conclude that TRIZ does improve the ideation effectiveness metrics Novelty and Variety while slightly reducing Quantity when compared to a control group using ad hoc ideation methods.
Characterization of Fluid Film Produced by an Atomization-Based Cutting Fluid Spray System During Machining
Authors: Hoyne Alexander C. , Nath Chandra , Kapoor Shiv G.
Published: September 2013

The atomization-based cutting fluid (ACF) spray system has recently been proposed as a cooling and lubrication solution for machining hard to machine materials (e.g., titanium alloys). On the tool rake face, the ACF spray system forms a thin film from cutting fluid that penetrates into the tool–chip interface to improve tool life. The objective of this work is to characterize this thin fluid film in terms of thickness and velocity for a set of ACF spray parameters. ACF spray experiments are performed by varying impingement angle to observe the nature of the spreading film and to determine the film thickness at different locations after impingement of the droplets. It is observed that the film spreads radially outward producing three fluid film development zones (i.e., impingement, steady, and unsteady). The steady zone is found to be between 3 and 7 mm from the focus (impingement point) of the ACF spray for the set of parameters investigated. An analytical 3D thin fluid film model for the ACF spray system has also been developed based on the Navier–Stokes equations for mass and momentum. The model requires a unique treatment of the cross-film velocity profile, droplet impingement, and pressure distributions, as well as a strong gas–liquid shear interaction. The thickness profiles predicted by the analytical film model have been validated. Moreover, the model predictions of film velocity and chip flow characteristics during a titanium turning experiment reveal that the fluid film can easily penetrate into the entire tool–chip interface with the use of the ACF spray system.
Height Dependent Laser Metal Deposition Process Modeling
Authors: Sammons Patrick M. , Bristow Douglas A. , Landers Robert G.
Published: September 2013

Laser metal deposition (LMD) is used to construct functional parts in a layer-by-layer fashion. The heat transfer from the melt region to the solid region plays a critical role in the resulting material properties and part geometry. The heat transfer dynamics can change significantly as the number of layers increase, depending on the geometry of the sub layers. However, this effect is not taken into account in previous analytical models, which are only valid for a single layer. This paper develops a layer dependent model of the LMD process for the purpose of designing advanced layer-to-layer controllers. A lumped-parameter model of the melt pool is introduced and then extended to include elements that capture height dependent effects on the melt pool dimensions and temperature. The model dynamically relates the process inputs (laser power, material mass flow rate, and scan speed) to the melt pool dimensions and temperature. A finite element analysis (FEA) is then conducted to determine the effect of scan speed and part height on the solid region temperature gradient at the melt pool solidification boundary. Finally, experimental results demonstrate that the model successfully predicts multilayer phenomenon for two deposits on two different substrates.
Sustainability Indicators for Grinding Applied to Dressing Strategies
Authors: Sabine Linke Barbara
Published: September 2013

Growing environmental awareness leads production engineers to focus increasingly on energy and material efficiency of manufacturing processes. However, only a few holistic approaches have been applied on the manufacturing process level and they often disregard product quality. In this study, sustainability indicators for the discrete manufacturing process of grinding are defined and discussed. Various temporal and spatial boundaries for the sustainability analysis are evaluated with regard to their effect on the results. Selected indicators, here energy and waste intensity, are then used to evaluate different dressing strategies in a case study. This study highlights the challenges in setting the boundaries for a sustainability analysis and stresses the importance of clearly defining these in research papers.
A Classification of Action Origami as Systems of Spherical Mechanisms
Authors: Bowen Landen A. , Grames Clayton L. , Magleby Spencer P. , Howell Larry L. , Lang Robert J.
Published: September 2013

Action origami is a field of origami dealing with models that are folded so that in their final, deployed state they exhibit motion. Hundreds of action origami models exist, many of which use complicated kinematics to achieve motion in their deployed state. A better understanding of the mechanisms used to create motion in action origami could be a foundation for developing a new source of concepts for deployable, movable engineering solutions. This brief presents an approach for evaluating and classifying the mechanisms that enable action origami motion. Approximately 130 action origami models are investigated. Although disguised with artistic elements, it is found that most action origami models are based on a few fundamental mechanisms. A classification scheme is proposed, and an unexplored class of action origami is identified as an area for future origami art.
Viscoelastic Properties of the P17 and Adult Rat Brain From Indentation in the Coronal Plane
Authors: Elkin Benjamin S. , Morrison Barclay
Published: September 2013

This technical brief serves as an update to our previous work characterizing the region-dependence of viscoelastic mechanical properties of the P17 and adult rat brain in the coronal plane (Elkin et al., 2011, “A Detailed Viscoelastic Characterization of the P17 and Adult Rat Brain,” J. Neurotrauma, 28, pp. 2235–2244.). Here, modifications to the microindentation device provided for the reliable measurement of load during the ramp portion of load relaxation microindentation tests. In addition, a correction factor for finite sample thickness was incorporated to more accurately assess the intrinsic mechanical properties of the tissue.The shear relaxation modulus was significantly dependent on the anatomic region and developmental age, with a general increase in stiffness with age and increased stiffness in the hippocampal and cortical regions compared with the white matter and cerebellar regions of the brain. The shear modulus ranged from ∼0.2 kPa to ∼2.6 kPa depending on region, age, and time scale. Best-fit Prony series parameters from least squares fitting to the indentation data from each region are reported, which describe the shear relaxation behavior for each anatomic region within each age group at both short (<10 ms) and long (∼20 s) time scales. These data will be useful for improving the biofidelity of finite element models of rat brain deformation at short time scales, such as models of traumatic brain injury.
Comparative Assessment of the Laser Induced Plasma Micromachining and the Micro-EDM Processes
Authors: Pallav K. , Han P. , Ramkumar J. , Nagahanumaiah  , Ehmann K. F.
Published: September 2013

Micro-electro-discharge machining (micro-EDM) is a well-established micromanufacturing process and has been at the center of research for the last few decades. However, it has its own limitations. The limitations are primarily due to the requirement of a tool and electric potential between the tool and the workpiece. The laser induced plasma micromachining (LIP-MM) is a novel tool-less multimaterial selective material removal type of micromachining process. In a manner similar to micro-EDM, it also removes material through plasma-matter interaction. However, instead of a tool and electric potential, it uses an ultra-short laser beam to generate plasma within a transparent dielectric media and thus circumvents some of the limitations associated with micro-EDM. The paper presents an experimental investigation on the comparative assessment of the capabilities of the two processes in the machining of microchannels in stainless steel. For comparative assessment of their processing capabilities, microchannels were machined by the two processes at similar pulse energy levels, while other process parameters were maintained at their optimal values for their respective process technology requirements. The comparative assessment was based on the geometric characteristics, material removal rate (MRR), effect of tool wear, and the range of machinable materials.
Soil Effect on the Finite Simply Supported Plate Vibration
Authors: Laulagnet Bernard
Published: September 2013

We are interested in the vibration prediction for a finite flexural plate lying on a semi-infinite soil, whose surface is free, except under the plate. Both the plate equation and the Navier equations are solved, using their bidimensional spatial Fourier Transforms. A cousin problem is the one of the acoustic radiation of the unbaffled plate, a one velocity problem. In this soil problem, two velocities are taken into account, the soil shear and dilatation velocities, considered as a visco-elastic homogeneous medium. Finally, expanding the plate displacement on its modes, linear systems in plate displacement amplitude are solved. As for the unbaffled acoustic radiation problem, equivalent vibratory radiation impedances set is proposed, totally new, describing the modal coupling between the plate modes and the soil. It is shown, contrary to the acoustic one velocity problem that the sign of the imaginary part of the complex vibratory radiation terms is negative at very low frequency, and positive above, meaning that the soil adds stiffness to the plate at low frequency and mass above. The soil effect on the plate vibration is of first importance, highly decreasing the plate vibration by more than 30 dB even for thick concrete plates.
Development and Validation of Turbulence Ingestion Prediction Capability of TONBROD
Authors: Paul Brent S. , Uhlman James S.
Published: September 2013

With alternative energy becoming more prevalent the acoustic impact of machinery used to generate the energy is of interest. The noise produced from wind turbines is an important factor in the design as it can affect nearby communities. A numerical tool has been developed to predict the unsteady thrust and directly radiated noise from a single or multi-blade row turbomachine, which can easily be applied to a wind turbine.

The tool, called TONBROD, can predict blade rate and turbulence ingestion noise, however only the latter is of concern for this work. An asymptotic approach is used to quickly and efficiently predict the unsteady force on each blade from the chopping of incoming turbulence (e.g. turbulence ingestion noise). This force is then used to estimate the radiated noise. A user can prescribe the incoming turbulence intensity (circumferentially and radially varying) and integral length scale (circumferentially uniform but radially varying) that is then modified by the upstream blade row and advected to the downstream blade row through semi-empirical formulations. A prediction of the resulting unsteady force and noise is then made for either blade row. The asymptotic theory is briefly discussed and then the prediction of radiated noise for both homogeneous and inhomogeneous turbulence is compared to experimental data. It is shown that the method provides good results.
Wall Pressure Phase Velocity Measurements in a Turbulent Boundary Layer
Authors: Miller Teresa S. , Moeller Mark J.
Published: September 2013

The turbulent boundary layer that forms on the outer surfaces of vehicles can be a significant source of interior noise. In automobiles this is known as wind noise, and at high speeds it dominates the interior noise. For airplanes the turbulent boundary is also a dominant noise source. Because of its importance as a noise source, it is desirable to have a model of the turbulent wall pressure fluctuations for interior noise prediction. One important parameter in building the wall pressure fluctuation model is the convection velocity. In this paper, the phase velocity was determined from the streamwise pressure measurements. The phase velocity was calculated for three separation distances ranging from 0.25 to 1.30 boundary layer thicknesses. These measurements were made for a Mach number range of 0.1 < M < 0.6. The phase velocity was shown to vary with sensor spacing and frequency. The data collapsed well on outer variable normalization. The phase velocities were fit and the group velocity was calculated from the curve fit. The group velocity was consistent with the array measured convection velocities. The group velocity was also estimated by a band limited cross correlation technique that used the Hilbert transform to find the energy delay. This result was consistent with the group velocity inferred from the phase velocities and the array measured convection velocity. From this research, it is suggested that the group velocity found in this study should be used to estimate the convection velocity in wall pressure fluctuation models.
Noise Assessment of Bioethanol Fuelled Hybrid and Electric Postal Vehicles Equipped With a Kinetic Energy Recovery System
Authors: Goretti Michele , Nicolini Andrea , Rossi Federico , Cotana Franco
Published: September 2013

In order to assess the contribution of sustainable mobility to improve environmental conditions in urban areas, new generation hybrid and electric models of mail delivery vehicles are analysed in terms of their noise emissions. Both vehicles use a 10% bioethanol and 90% gasoline mixture (E10) for recharging their batteries and they are equipped with a kinetic energy recovery system (KERS). The difference is the recharge modality: the hybrid vehicle is equipped on board with an E10 fuelled engine for the recharge of its electric batteries while the electric vehicle may be recharged by an E10 engine installed on a specific station (engine is not on board). The aims of the present paper are to carry out objective noise measurements representing realistic urban driving conditions and to compare the noise emissions of the tested vehicles with the ones of traditional postal vehicles. Vehicle sound pressure levels are evaluated according to the international standard ISO 362-1 and the UN/ECE Regulation n. 51 and they reflect a representative combination of all major noise sources. SEL measurements are also analysed as an alternative assessment of noise due to accelerating postal vehicles in actual traffic conditions. Finally all results are compared and their contribution to optimize vehicle noise emission is analysed.
Vibroacoustic Characterization of a New Hybrid Wing-Body Fuselage Concept
Authors: Allen Albert , Przekop Adam
Published: September 2013

A lighter, more robust airframe design is required to withstand the loading inherent to next generation non–cylindrical commercial airliners. The Pultruded Rod Stitched Efficient Unitized Structure concept, a highly integrated composite design involving a stitched and co-cured substructure, has been developed to meet such requirements. While this structure has been shown to meet the demanding out-of-plane loading requirements of the flat-sided pressurized cabin design, there are concerns that the stiff co-cured details will result in relatively high acoustic radiation efficiencies at frequencies well below the thin skin acoustic coincidence frequency. To address this concern and establish a set of baseline vibroacoustic characteristics, a representative test panel was fabricated and a suite of tests were conducted that involved measurements of panel vibration and radiated sound power during point force and diffuse acoustic field excitations. Experimental results are shown and compared with Finite Element and Statistical Energy Analysis model predictions through the use of modal and energy correlation techniques among others. The behavior of the structure subject to turbulent boundary layer excitation is also numerically examined.
Superelement Reduction of Industrial Finite Element Brake System for a Constrained Harmonic Balance Method
Authors: Villard Paul , Nacivet Samuel , Sinou Jean-Jacques
Published: September 2013

Brake squeal is a ubiquitous disturbance in automotive systems. Facing the complexity and the cost of experimental tests, simulations of brake squeal have become essential as well as to provide a predictive numerical method. Two major approaches exist in the numerical analysis of this phenomenon, the transient analysis and the complex eigenvalue analysis. In this study, the Constrained Harmonic Balance Method is applied on an industrial finite element system in order to estimate the nonlinear stationary responses due to friction induced vibration. This paper aims at explaining how a finite element system was adapted to the CHBM and at analyzing the results. First of all, the method used to reduce a finite element brake system is examined and the contact issue is particularly emphasized. Then, a brief summary of the CHBM is made. Finally, limit cycles are obtained close to the Hopf bifurcation.
Hearing Protection With Integrated In-Ear Dosimetry: A Noise Dose Study
Authors: Theis Melissa A. , Gallagher Hilary L. , McKinley Richard L. , Bjorn Valerie S.
Published: September 2013

Military personnel working in high noise environments can be exposed to continuous noise levels up to 150 dB. United States (US) Department of Defense (DoD) Hearing Conservation Programs (HCPs) [1–3] set safe noise exposure limits to reduce the risk for noise induced hearing loss. These daily noise exposure limits were based on ambient noise levels and the duration of time spent in that noise environment. Current dosimeters, worn on the lapel of personnel and at least one system worn under a hearing protector, were designed to measure noise levels and calculate noise dose, but do not provide a validated measure of noise dose external to or under a hearing protector. Noise dose under hearing protectors can be estimated by subtracting the real ear attenuation (REAT) data, collected in accordance with the American National Standards Institute (ANSI) S12.6 [4], at each octave band from the ambient octave band noise. This procedure gives accurate results for group data, but does not account for individual variations in effective attenuation. To address this issue, the US Naval Air Systems Command (NAVAIR) led the development of ship suitable in-ear dosimetry integrated into a hearing protector, and co-sponsored an effort executed by the Air Force Research Laboratory (AFRL) to calibrate in-ear noise dose readings. This was accomplished by conducting human noise exposure experiments, with and without hearing protection, which calculated noise dose from temporary threshold shifts (TTS) in hearing. Ten subjects participated in the study. Noise levels were 91, 94, and 97 dB for up to 2 hrs, 1 hr, and 30 minutes respectively. These exposure levels were well within US DoD safe noise exposure guidelines (DoD HCP) [1–3]. Data will be presented describing the open and occluded (protected) ear TTS response to noise dose achieved by subjects in the experiment. Preliminary findings indicate that human subject data is extremely important in developing and validating calibration factors for any type of noise dosimeter but is especially important for in-ear dosimetry. Results from this study demonstrated that the REAT noise dose estimations and the in-ear dosimetry earplugs consistently overestimated the effective noise dose received by subjects. However, more than 10 subjects are required to improve the confidence level of the estimated calibration factor.
Numerical Evaluation of the Compact Green’s Function for the Solution of Acoustic Flows
Authors: Harwood Adrian R. G. , Dupère Iain D. J.
Published: September 2013

Due to the relatively tiny length scales involved, complex acoustic flows are not always suitable for traditional CFD codes. This paper develops a robust, semi-analytical numerical method for predicting sound fields based on the calculation of the compact Green’s function over a grid of source-observer positions. These calculations often involve singular functions, hence variations of the method are applied to several different 2D problems to investigate the impact of any singularities on the solution. The effect of grid point density and other parameters on execution time and accuracy are explored including the effects of approximating curved geometries using a number of straight lines. Comparison to known analytical solutions for the 2D problems is used to assess the accuracy of the method. For a typical application, we compute the far-field sound generated by a simple source in the vicinity of a compact, ‘2D’ fan blade in a duct. The current method demonstrates calculation of the compact Green’s function both accurately and robustly by avoiding the mapping from unbounded domains and the evaluation of potential models containing singularities. Both are seen as sources of error which have a widespread impact.
Sound Propagation in a Sheared Flow Based on Fluctuating Total Enthalpy as Generalized Acoustic Variable
Authors: Legendre César , Lielens Gregory , Coyette Jean-Pierre
Published: September 2013

Noise propagation mechanisms in presence of a rotational flow are currently receiving some attention from the aircraft industry. Different methods are used in order to compute the acoustic wave propagation in sheared flows in terms of pressure perturbations (e.g. Linearized Euler Equations (LEE), Lilley’s and Galbrun’s equations). Nevertheless, they have drawbacks in terms of computational performance (high number of DOFs per node, inadequacies of classical numerical schemes like standard FE). In contrast with other studies, in this work, the fluctuating total enthalpy is selected as the main variable in order to describe the acoustic field, which obeys to a convected wave equation obtained by linearization of momentum (Crocco’s form), energy and continuity equations and with coefficients depending on flow variables. The resulting 3D convected wave operator is an extension of the Möhring acoustic analogy which is able to predict the sound propagation through rotational flows in the subsonic regime and is well adapted to FE discretization. A 2D convected wave equation is generated from the previous operator. This is followed by a numerical solution based on FEM with two types of boundary conditions: non reflecting BC and incident plane wave excitation. The numerical results are used to estimate the reflection coefficient generated by the shear flow. The new acoustic wave operator is compared to well-known theories of flow acoustics (Pridmore-Brown wave operator) and shows promising results. Finally additional development steps are presented so further improvements on the new operator can be carried out.