bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Dynamic Modulus Values of Asphalt Mixtures Using Impact Resonance Testing of Thin Disk Specimens
Authors: Kim D. , Kim Y. R. 
Published: February 2016

Abstract
The impact resonance (IR) test is a nondestructive test method that is used to characterize the linear viscoelastic behavior of asphalt concrete. This method is preferred over other methods because the setup of the IR test is simpler, more efficient, and less expensive than standard axial compression dynamic modulus (|E*|) tests. Researchers originally developed the IR test method for cylindrical specimens of asphalt mixtures and concluded that this method can serve as an alternative to |E*| tests. However, the geometry (100 mm in diameter by 150 mm in height) of the cylindrical specimens used in these tests prohibits the use of IR tests for field cores. Therefore, researchers began to consider thin disk-shaped specimens for IR testing because thinner geometry of such specimens better represents slices of field cores. In this study, a test procedure was developed to evaluate the use of thin disk-shaped specimens for IR tests in order to determine the |E*| values of asphalt mixtures. The IR test protocol was optimized using 2 IR test methods (referred to as Case 1 and Case 2 in this work) under various test conditions to ensure the highest possible quality of the data. Optimal test methods were proposed based on the repeatability and variability of the resonant frequency and phase angle data and the ability of the different test conditions to provide data that best match the |E*| values obtained from standard axial compression |E*| tests. The results demonstrate that the |E*| values of thin disk-shaped specimens determined from the optimized IR tests are similar to the |E*| values of long cylindrical specimens determined from conventional |E*| AASHTO T 342-11 tests and IR tests.
Analysis of Masked Data in a Series System Subjected to Sources of Shocks Under Type I Progressive Hybrid Censoring
Authors: Cai J. , Shi Y. , Liu B. 
Published: February 2016

Abstract
In this paper, we consider the statistical analysis of masked data based on the fatal shock model under type I progressive hybrid censoring. It is assumed that the time of shock follows Weibull distribution. Maximum-likelihood estimators for the unknown parameters are obtained by solving a one-dimensional optimization problem. Approximate maximum-likelihood estimators have been proposed based on a Taylor series expansion, and they have explicit expressions. In addition, the Bayesian approach, combined with Gibbs sampling, are developed based on the assumption that the shape parameter has a log-concave function, and for the given shape parameter, the scale parameters have Gamma-Dirichlet priors. Finally, Monte Carlo simulations are performed to compare the performances of the proposed methods under different progressive censoring schemes and masking levels.
Aggregate Gradation Influence on Grouting Results and Mix Design of Asphalt Mixture Skeleton for Semi-Flexible Pavement
Authors: Hou Shuguang , Xu Tao , Huang Kai 
Published: February 2016

Abstract
In this study, to design a satisfactory asphalt mixture skeleton for semi-flexible pavement (SFP), the effects of aggregate gradation on grouting results of porous asphalt mixture were analyzed based on the test results of 22 aggregate gradations. Moreover, the mix design method of asphalt mixture skeleton was also discussed. Results indicated that the grouting effects of asphalt mixture skeleton were affected by its internal void interconnectivity, including the morphological characteristics, structure, and size of pores, instead of the initial void volume (VV). The grouting effects of asphalt mixture skeleton were influenced by the fine aggregate at the specific particle size levels. An increase in the mixing proportion of coarse aggregates could improve the grouting effects. A valid mix design approach was developed to prepare the asphalt mixture skeleton of SFP. Finally, engineering properties of the grouted mixture specimens were validated. It was concluded that the aggregation gradation design was a very important aspect in effecting the grouting results of an asphalt mixture skeleton. Furthermore, the aggregate gradation should be selected to facilitate the cement slurry to permeate in full thickness of the asphalt mixture skeleton layer. This could be used to direct the design of asphalt mixture skeleton toward lessening field failures on the SFP.
Flexural Strength Tests of Brittle Materials: Selecting the Number of Specimens and Determining Confidence Limits for Weibull Parameters
Authors: McCool J. I. 
Published: February 2016

Abstract
The flexural strength of brittle materials has been found to follow the two-parameter Weibull distribution. This paper describes a simple method of estimating the Weibull modulus and characteristic strength that allows for the computation of confidence intervals that will contain the true values within a specifiable level of confidence. The sample size needed to meet the experimenter's precision requirements is determined. A sample of flexural strength data from the literature is used to illustrate all of the computations. The precision of the method is compared to that of the method of maximum likelihood. It is found to be inferior to maximum likelihood for estimating the Weibull modulus but quite comparable for estimating the scale parameter.
Comparative Biaxial Flexural Behavior of Ultra-High-Performance Fiber-Reinforced Concrete Panels Using Two Different Test and Placement Methods
Authors: Yoo Doo-Yeol , Banthia Nemkumar , Zi Goangseup , Yoon Young-Soo 
Published: February 2016

Abstract
In order to investigate the effects of fiber length, placement method, and test method on the biaxial flexural behaviors of ultra-high-performance fiber-reinforced concrete (UHPFRC), several UHPFRC panels with two different fiber lengths (Lf of 13 and 19.5 mm) were fabricated using two different placement methods (placing concrete at the center and the edge) and were then tested by two different test methods (ASTM C1550-12a and a novel biaxial flexure test (BFT)). Image analysis was also performed to quantitatively investigate the fiber distribution characteristics according to the fiber length and placement method and to thoroughly analyze the experimental results. The first cracking strength and corresponding toughness were found to be insignificantly influenced by the fiber length, placement method, and test method, but the panels with longer fibers and with concrete placed at the center (in the maximum moment region) were found to have higher biaxial flexural strength, deflection capacity, and toughness after a deflection of 2.5 mm (d2.5). The panels tested by the BFT method showed lower flexural strength, more cracks with a random distribution, and higher deviation in flexural performances than those tested by ASTM C1550. These test results were verified by evaluating the fiber distribution characteristics (i.e., the number of fibers per unit area, fiber orientation, and fiber dispersion) at localized crack surfaces by using the image analysis technique.
Application of Heat of Wetting for Determination of Soil-Specific Characteristics of Fine-Grained Soils
Authors: Kadali Srinivas , Susha Lekshmi S. U. , Singh D. N. , Shojaei Baghini Maryam 
Published: February 2016

AbstractConventionally, particle size distribution characteristics and consistency limits have been used to characterize fine-grained soils. However, these schemes of soil characterization are devoid of several other soil-specific parameters (viz., specific surface area, specific gravity, weight loss during heating, heat produced during the interaction of soil with water, chemical and mineralogical composition, zeta potential, cation-exchange capacity, and reactivity) that imbibe in them physical, chemical, mineralogical, and thermal characteristics or, in short, the “overall characteristics” of the soil. These characteristics are also useful to define soils with pollutants and contaminants, which result from rapid and indiscriminate industrialization. Hence, characterization of the soil based on its “heat of wetting,” which imbibes the specific characteristics of the soil and is measured by the percentage increase in temperature (PIT) when soil-water interaction occurs, appears to be quite prudent and a novel idea or hypothesis. With this in view and to develop a soil characterization scheme, soils of completely different characteristics were allowed to interact with water in a calorimeter, and the PIT was measured precisely by employing a thermocouple. The PIT and various soil-specific parameters when correlated with each other yielded well-defined relationships. Utility of these relationships for a quick and easy characterization of fine-grained soils has also been demonstrated in this study.
Mechanical Responses of Rock Joints With Regular Asperities Under Various Shear Rates Investigated by Double Shear Test
Authors: Li H. H. 
Published: February 2016

Abstract
To study the mechanical responses of rock joints within a wide range of shear rates, this study develops a horizontal gripping mechanism to improve a double shear test device. Artificial rock joints, including planar and regular asperities with dip angles of 15° and 30°, are produced for conducting double shear tests under constant normal load within the shear rate range of 10−2–101 mm/s. Experimental results demonstrate that, though normalized by applied normal stress, the shear stiffness of the planar joints has a semi-logarithmic linear relationship with normalized shear rates. For rock joints with regular asperities, the shear rate, asperity dip angle, and normal stress influence the failure modes of asperities. When the shear rate is lower than the threshold shear rate, the asperity dip angles after the shear process and the peak dilation angles of the 15° regular joints increase with increasing the shear rate, whereas these two parameters tend to decrease in the cases of the 30° regular joints. The peak friction angles of both planar and regular rock joints have a semi-logarithmic linear relationship with normalized shear rates. The increasing peak friction angles of rock joints at different shear rates after sliding or local cut-off failures are derived mainly from increased basic friction angles. Both the basic friction angles of rock joints and the shear strength of asperities rise as the shear rate increases when asperity cut-off occurs. However, the quantitative effect of these two factors on the increase of peak friction angle requires further study.
Effect of Adhesion and Cohesion on Ductile Fracture in Cylindrical Upsetting Process
Authors: Chirala H. K. , Davidson M. J. , Cherukuri N. , Raju P. S. , Rao G. S. 
Published: February 2016

AbstractThe lubricants employed at the die/billet interface reduce the adhesion and improve the formability of the AA 2014-T6 billets by avoiding cracks. The friction factor obtained from the ring compression test for different lubricants was correlated with the hypothesis of ductile fracture based on void failures to examine the damage rate with the increasing strain. Mohr–Coulomb criterion was employed for observing the cohesive failure for different aluminum alloys. The fitting parameters in the Mohr–Coulomb criterion were varied to study the influence of the process parameters on the fracture strain. The hardness variation in the billets for different stress triaxialities and Lode parameters was also investigated by constitutive modeling of the hardness with the equivalent strain.
Strength and Fracture Characterization of a Novel Polyurethane Adhesive for the Automotive Industry
Authors: Faneco T. M. S. , Campilho R. D. S. G. , Silva F. J. G. , Lopes R. M. 
Published: February 2016

Abstract
Adhesive bonding by structural adhesives has been used for several decades, helping to solve various problems related to the conventional joining techniques, such as welding, riveting, or bolting. Adhesive joints present less structural weight, lower manufacturing cost, the possibility to join different materials, and high fatigue strength. The increasing use of composite materials also helped to the growing use of adhesive joints, since these do not break the reinforcing fibers' continuity. An adhesive joint is mainly subjected to peel and shear loads. However, the knowledge of the tensile (E) and shear (G) moduli of the adhesive, and its tensile (σf) and shear failure strengths (τf), is not enough to predict the joint behavior. In fact, the critical strain energy release rate in tension (GIc) and shear (GIIc) are equally necessary for advanced modelling techniques such as cohesive zone modelling (CZM). This work aimed to study a novel structural polyurethane adhesive to obtain material property data that can be further used for the strength prediction of bonded structures. With this purpose, 4 tests were performed: tensile testing to bulk specimens, shear testing with thick adherend shear tests (TAST), double-cantilever beam (DCB), and end-notched flexure (ENF) tests. These tests will allow values to be determined for the mechanical and fracture properties of the adhesive in tension and shear. The parameters to predict the strength of adhesive joints with this adhesive by various methods were provided, ranging from the easy to apply analytical methods to the most advanced numerical methods available nowadays. A detailed comparison is also undertaken with an adhesive of the same family. The obtained results were in close agreement with the few data provided by the manufacturer (E and σf), while fracture data was also provided with a good agreement between data reduction schemes.
AFM Evaluation of Pre-Straining Degree Effects on the Dimensions of Stress Induced Martensite Plates in Fe-Mn-Si Based SMAs
Authors: Suru M.-G. , Lohan N.-M. , Mihalache E. , Pricop B. , Mocanu M. , Bujoreanu L.-G. 
Published: February 2016

Abstract
By means of atomic force microscopy (AFM) measurements, the evolution of surface relief characteristics of stress induced martensite plates was investigated on the surface of polished Fe-14Mn-6Si-9Cr-5Ni and Fe–28Mn–6Si–5Cr (mass. %) shape memory alloys (SMAs), subjected to various pre-straining degrees. Pre-straining degree was chosen as an independent variable, considering its influence on the reverse transformation of martensite. The specimens were cast by means of a levitation induction furnace and hot rolled to 1 mm-thickness in order to better reveal the shape memory phenomena. The specimens, cut by spark erosion to “dog-bone” shapes, were pre-strained by means of a tensile testing machine at room temperature (RT). The gauges of elongated specimens were analyzed by AFM. Qualitative 2D analyses were performed on AFM micrographs. Quantitative evaluations were based on systematic dimensional measurements of martensite profiles, allowing the determination of the average values of plate widths and heights for four pre-straining degrees of the two SMA systems under study. The variation tendencies of average values of martensite plate widths and heights with increasing the pre-straining were examined under the form of increasing rates of the plate widths and heights. The results show that, for the two SMA systems studied, the average widths and heights of stress-induced martensite plates varied between 80 and 188 nm for Fe-14Mn-6Si-9Cr-5Ni and between 101 and 192 nm for Fe-28Mn-6Si-5Cr. These dimensions experienced an increasing tendency with pre-straining degree, with a rate of about 30 nm/ % pre-strain.
Results for a Fuel Cell System Consisting of an SOFC Fed by an Adiabatic Pre-Reforming Fuel Processor With European Standard Road Diesel
Authors: Kleinohl N. , Hansen J. B. , Nehter P. , Modarresi H. , Bauschulte A. , vom Schloß J. , Lucka K. 
Published: February 2016

Abstract
In the near future, ships will need more efficient power generation technologies for auxiliary power supply than those used currently. In the project SchiffsIntegration BrennstoffZelle (SchIBZ), a fuel cell system is being developed to increase the electrical efficiency of on-board power supply systems. In order to avoid the limitation of hydrogen storage, the on-site fuel processing of hydrocarbons offered an opportunity for the hydrogen supply of fuel cell systems to be operated in remote locations. As fuel standard European road diesel was processed with the process of adiabatic pre-reforming, a steam-reforming derivate. A solid oxide fuel cell (SOFC) was coupled with this fuel processor and was fed with standard European diesel fuel. Two flexible test rigs were developed to test the fuel processor and the SOFC either combined or independently. During combined operation, the SOFC modules were fed with feedstock gas from the fuel processor, which ran on standard European diesel fuel. Combined operation of both test rigs at steady state was achieved for more than 1000 h. For the whole experimental runtime, the fuel processor delivered sufficient feedstock quality for the SOFC, and no significant voltage degradation (about 0.5 %) of the SOFC modules was observed over 1000 h of operation. This low value of degradation is known for the operation of SOFC with pure hydrogen and methane without impurities.
Persistent Electrical Activity in Primary Nociceptors after Spinal Cord Injury Is Maintained by Scaffolded Adenylyl Cyclase and Protein Kinase A and Is Associated with Altered Adenylyl Cyclase Regulation
Authors: Bavencoffe Alexis , Li Yong , Wu Zizhen , Yang Qing , Herrera Juan , Kennedy Eileen J. , Walters Edgar T. , Dessauer Carmen W. 
Published: February 2016

Little is known about intracellular signaling mechanisms that persistently excite neurons in pain pathways. Persistent spontaneous activity (SA) generated in the cell bodies of primary nociceptors within dorsal root ganglia (DRG) has been found to make major contributions to chronic pain in a rat model of spinal cord injury (SCI) (Bedi et al., 2010; Yang et al., 2014). The occurrence of SCI-induced SA in a large fraction of DRG neurons and the persistence of this SA long after dissociation of the neurons provide an opportunity to define intrinsic cell signaling mechanisms that chronically drive SA in pain pathways. The present study demonstrates that SCI-induced SA requires continuing activity of adenylyl cyclase (AC) and cAMP-dependent protein kinase (PKA), as well as a scaffolded complex containing AC5/6, A-kinase anchoring protein 150 (AKAP150), and PKA. SCI caused a small but significant increase in the expression of AKAP150 but not other AKAPs. DRG membranes isolated from SCI animals revealed a novel alteration in the regulation of AC. AC activity stimulated by Ca2+-calmodulin increased, while the inhibition of AC activity by Gαi showed an unexpected and dramatic decrease after SCI. Localized enhancement of the activity of AC within scaffolded complexes containing PKA is likely to contribute to chronic pathophysiological consequences of SCI, including pain, that are promoted by persistent hyperactivity in DRG neurons.SIGNIFICANCE STATEMENTChronic neuropathic pain is a major clinical problem with poorly understood mechanisms and inadequate treatments. Recent findings indicate that chronic pain in a rat SCI model depends upon hyperactivity in dorsal root ganglia (DRG) neurons. Although cAMP signaling is involved in many forms of neural plasticity, including hypersensitivity of nociceptors in the presence of inflammatory mediators, our finding that continuing cAMP-PKA signaling is required for persistent SA months after SCI and long after isolation of nociceptors is surprising. The dependence of ongoing SA upon AKAP150 and AC5/6 was unknown. The discovery of a dramatic decrease in Gαi inhibition of AC activity after SCI is novel for any physiological system and potentially has broad implications for understanding chronic pain mechanisms.
Remyelinating Oligodendrocyte Precursor Cell miRNAs from the Sfmbt2 Cluster Promote Cell Cycle Arrest and Differentiation
Authors: Kuypers Nicholas J. , Bankston Andrew N. , Howard Russell M. , Beare Jason E. , Whittemore Scott R. 
Published: February 2016

Oligodendrocyte (OL) loss contributes to the functional deficits underlying diseases with a demyelinating component. Remyelination by oligodendrocyte progenitor cells (OPCs) can restore these deficits. To understand the role that microRNAs (miRNAs) play in remyelination, 2′,3′-cyclic-nucleotide 3′-phosphodiesterase-EGFP+mice were treated with cuprizone, and OPCs were sorted from the corpus callosum. Microarray analysis revealed that Sfmbt2 family miRNAs decreased during cuprizone treatment. One particular Sfmbt2 miRNA, miR-297c-5p, increased during mouse OPC differentiationin vitroand during callosal developmentin vivo. When overexpressed in both mouse embryonic fibroblasts and rat OPCs (rOPCs), cell cycle analysis revealed that miR-297c-5p promoted G1/G0arrest. Additionally, miR-297c-5p transduction increased the number of O1+rOPCs during differentiation. Luciferase reporter assays confirmed that miR-297c-5p targets cyclin T2 (CCNT2), the regulatory subunit of positive transcription elongation factor b, a complex that inhibits OL maturation. Furthermore, CCNT2-specific knockdown promoted rOPC differentiation while not affecting cell cycle status. Together, these data support a dual role for miR-297c-5p as both a negative regulator of OPC proliferation and a positive regulator of OL maturation via its interaction with CCNT2.SIGNIFICANCE STATEMENTThis work describes the role of oligodendrocyte progenitor cell (OPC) microRNAs (miRNAs) during remyelination and developmentin vivoand differentiationin vitro. This work highlights the importance of miRNAs to OPC biology and describes miR-297c-5p, a novel regulator of OPC function. In addition, we identified CCNT2 as a functional target, thus providing a mechanism by which miR-297c-5p imparts its effects on differentiation. These data are important, given our lack of understanding of OPC miRNA regulatory networks and their potential clinical value. Therefore, efforts to understand the role of miR-297c-5p in pathological conditions and its potential for facilitating repair may provide future therapeutic strategies to treat demyelination.