Dispersion analysis of collagen fiber networks in cervical tissue using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gan, Yu; Yao, Wang; Myers, Kristin M.; Vink, Joy Y.; Wapner, Ronald J.; Hendon, Christine P.

2016-02-01

Understanding the human cervical collagen fiber network is critical to delineating the physiology of cervical remodeling during pregnancy. Previously, we presented our methodology to study the ultrastructure of collagen fibers over an entire field of transverse slices of human cervix tissue using optical coherence tomography. Here, we present a pixel-wise fiber orientation method to enable dispersion analysis on entire slices of human cervical tissues. We obtained en face images that were parallel to the surface. In each en face image, we masked the collagen fiber region based on signal noise ratio. Then, we extracted fiber orientations in each pixel using a weighted summation scheme and generated a pixel-wise directionality map within the entire region. The weight was determined by intensity variations between a pixel of interest and its neighboring pixels and their corresponding distances. We divided the directionality map into regions of 400 μm × 400 μm along radial direction in all four quadrants. In each region, we fit von-Mises distribution to fiber orientations of pixels with mode θ and dispersion b. We compared dispersions among regions and samples. Using IRB approved protocols, we obtained whole transverse slices of cervical tissue from pregnant (n = 2) and non-pregnant (n = 13) women. We observed higher dispersion in pregnant samples compared to non-pregnant samples and higher dispersions in patient's right/left zones than posterior/anterior zones within an axial slice. Future studies will analyze how collagen fiber dispersion patterns change from the internal to the external os.

Transmission Electron Microscopy of Bombyx Mori Silk Fibers

NASA Astrophysics Data System (ADS)

Shen, Y.; Martin, D. C.

1997-03-01

The microstructure of B. Mori silk fibers before and after degumming was examined by TEM, selected area electron diffraction (SAED), WAXS and low voltage SEM. SEM micrographs of the neat cocoon revealed a network of pairs of twisting filaments. After degumming, there were only individual filaments showing a surface texture consistent with an oriented fibrillar structure in the fiber interior. WAXS patterns confirmed the oriented beta-sheet crystal structure common to silkworm and spider silks. Low dose SAED results were fully consistent with the WAXS data, and revealed that the crystallographic texture did not vary significantly across the fiber diameter. TEM observations of microtomed fiber cross sections indicated a somewhat irregular shape, and also revealed a 0.5-2 micron sericin coating which was removed by the degumming process. TEM observations of the degummed silk fiber showed banded features with a characteristic spacing of nominally 600 nm along the fiber axis. These bands were oriented in a roughly parabolic or V-shape pointing along one axis within a given fiber. We hypothesize that this orientation is induced by the extrusion during the spinning process. Equatorial DF images revealed that axial and lateral sizes of the β-sheet crystallites in silk fibroin ranged from 20 to 170 nm and from 1 to 24 nm, respectively. Crazes developed in the degummed silk fiber parallel to the fiber direction. The formation of these crazes suggests that there are significant lateral interactions between fibrils in silk fibers.

Skeleton-based tracing of curved fibers from 3D X-ray microtomographic imaging

NASA Astrophysics Data System (ADS)

Huang, Xiang; Wen, Donghui; Zhao, Yanwei; Wang, Qinghui; Zhou, Wei; Deng, Daxiang

A skeleton-based fiber tracing algorithm is described and applied on a specific fibrous material, porous metal fiber sintered sheet (PMFSS), featuring high porosity and curved fibers. The skeleton segments are firstly categorized according to the connectivity of the skeleton paths. Spurious segments like fiber bonds are detected making extensive use of the distance transform (DT) values. Single fibers are then traced and reconstructed by consecutively choosing the connecting skeleton segment pairs that show the most similar orientations and radius. Moreover, to reduce the misconnection due to the tracing orders, a multilevel tracing strategy is proposed. The fibrous network is finally reconstructed by dilating single fibers according to the DT values. Based on the traced single fibers, various morphology information regarding fiber length, radius, orientation, and tortuosity are quantitatively analyzed and compared with our previous results (Wang et al., 2013). Moreover, the number of bonds per fibers are firstly accessed. The methodology described in this paper can be expanded to other fibrous materials with adapted parameters.

Collagen Fiber Orientation and Dispersion in the Upper Cervix of Non-Pregnant and Pregnant Women

PubMed Central

Myers, Kristin M.; Vink, Joy Y.; Wapner, Ronald J.; Hendon, Christine P.

2016-01-01

The structural integrity of the cervix in pregnancy is necessary for carrying a pregnancy until term, and the organization of human cervical tissue collagen likely plays an important role in the tissue’s structural function. Collagen fibers in the cervical extracellular matrix exhibit preferential directionality, and this collagen network ultrastructure is hypothesized to reorient and remodel during cervical softening and dilation at time of parturition. Within the cervix, the upper half is substantially loaded during pregnancy and is where the premature funneling starts to happen. To characterize the cervical collagen ultrastructure for the upper half of the human cervix, we imaged whole axial tissue slices from non-pregnant and pregnant women undergoing hysterectomy or cesarean hysterectomy respectively using optical coherence tomography (OCT) and implemented a pixel-wise fiber orientation tracking method to measure the distribution of fiber orientation. The collagen fiber orientation maps show that there are two radial zones and the preferential fiber direction is circumferential in a dominant outer radial zone. The OCT data also reveal that there are two anatomic regions with distinct fiber orientation and dispersion properties. These regions are labeled: Region 1—the posterior and anterior quadrants in the outer radial zone and Region 2—the left and right quadrants in the outer radial zone and all quadrants in the inner radial zone. When comparing samples from nulliparous vs multiparous women, no differences in these fiber properties were noted. Pregnant tissue samples exhibit an overall higher fiber dispersion and more heterogeneous fiber properties within the sample than non-pregnant tissue. Collectively, these OCT data suggest that collagen fiber dispersion and directionality may play a role in cervical remodeling during pregnancy, where distinct remodeling properties exist according to anatomical quadrant. PMID:27898677

CHARACTERIZATION OF THE COMPLETE FIBER NETWORK TOPOLOGY OF PLANAR FIBROUS TISSUES AND SCAFFOLDS

PubMed Central

D'Amore, Antonio; Stella, John A.; Wagner, William R.; Sacks, Michael S.

2010-01-01

Understanding how engineered tissue scaffold architecture affects cell morphology, metabolism, phenotypic expression, as well as predicting material mechanical behavior have recently received increased attention. In the present study, an image-based analysis approach that provides an automated tool to characterize engineered tissue fiber network topology is presented. Micro-architectural features that fully defined fiber network topology were detected and quantified, which include fiber orientation, connectivity, intersection spatial density, and diameter. Algorithm performance was tested using scanning electron microscopy (SEM) images of electrospun poly(ester urethane)urea (ES-PEUU) scaffolds. SEM images of rabbit mesenchymal stem cell (MSC) seeded collagen gel scaffolds and decellularized rat carotid arteries were also analyzed to further evaluate the ability of the algorithm to capture fiber network morphology regardless of scaffold type and the evaluated size scale. The image analysis procedure was validated qualitatively and quantitatively, comparing fiber network topology manually detected by human operators (n=5) with that automatically detected by the algorithm. Correlation values between manual detected and algorithm detected results for the fiber angle distribution and for the fiber connectivity distribution were 0.86 and 0.93 respectively. Algorithm detected fiber intersections and fiber diameter values were comparable (within the mean ± standard deviation) with those detected by human operators. This automated approach identifies and quantifies fiber network morphology as demonstrated for three relevant scaffold types and provides a means to: (1) guarantee objectivity, (2) significantly reduce analysis time, and (3) potentiate broader analysis of scaffold architecture effects on cell behavior and tissue development both in vitro and in vivo. PMID:20398930

Computational predictions of the tensile properties of electrospun fiber meshes: effect of fiber diameter and fiber orientation

PubMed Central

Stylianopoulos, Triantafyllos; Bashur, Chris A.; Goldstein, Aaron S.; Guelcher, Scott A.; Barocas, Victor H.

2008-01-01

The mechanical properties of biomaterial scaffolds are crucial for their efficacy in tissue engineering and regenerative medicine. At the microscopic scale, the scaffold must be sufficiently rigid to support cell adhesion, spreading, and normal extracellular matrix deposition. Concurrently, at the macroscopic scale the scaffold must have mechanical properties that closely match those of the target tissue. The achievement of both goals may be possible by careful control of the scaffold architecture. Recently, electrospinning has emerged as an attractive means to form fused fiber scaffolds for tissue engineering. The diameter and relative orientation of fibers affect cell behavior, but their impact on the tensile properties of the scaffolds has not been rigorously characterized. To examine the structure-property relationship, electrospun meshes were made from a polyurethane elastomer with different fiber diameters and orientations and mechanically tested to determine the dependence of the elastic modulus on the mesh architecture. Concurrently, a multiscale modeling strategy developed for type I collagen networks was employed to predict the mechanical behavior of the polyurethane meshes. Experimentally, the measured elastic modulus of the meshes varied from 0.56 to 3.0 MPa depending on fiber diameter and the degree of fiber alignment. Model predictions for tensile loading parallel to fiber orientation agreed well with experimental measurements for a wide range of conditions when a fitted fiber modulus of 18 MPa was used. Although the model predictions were less accurate in transverse loading of anisotropic samples, these results indicate that computational modeling can assist in design of electrospun artificial tissue scaffolds. PMID:19627797

A method to integrate patterned electrospun fibers with microfluidic systems to generate complex microenvironments for cell culture applications

PubMed Central

Wallin, Patric; Zandén, Carl; Carlberg, Björn; Hellström Erkenstam, Nina; Liu, Johan; Gold, Julie

2012-01-01

The properties of a cell’s microenvironment are one of the main driving forces in cellular fate processes and phenotype expression invivo. The ability to create controlled cell microenvironments invitro becomes increasingly important for studying or controlling phenotype expression in tissue engineering and drug discovery applications. This includes the capability to modify material surface properties within well-defined liquid environments in cell culture systems. One successful approach to mimic extra cellular matrix is with porous electrospun polymer fiber scaffolds, while microfluidic networks have been shown to efficiently generate spatially and temporally defined liquid microenvironments. Here, a method to integrate electrospun fibers with microfluidic networks was developed in order to form complex cell microenvironments with the capability to vary relevant parameters. Spatially defined regions of electrospun fibers of both aligned and random orientation were patterned on glass substrates that were irreversibly bonded to microfluidic networks produced in poly-dimethyl-siloxane. Concentration gradients obtained in the fiber containing channels were characterized experimentally and compared with values obtained by computational fluid dynamic simulations. Velocity and shear stress profiles, as well as vortex formation, were calculated to evaluate the influence of fiber pads on fluidic properties. The suitability of the system to support cell attachment and growth was demonstrated with a fibroblast cell line. The potential of the platform was further verified by a functional investigation of neural stem cell alignment in response to orientation of electrospun fibers versus a microfluidic generated chemoattractant gradient of stromal cell-derived factor 1 alpha. The described method is a competitive strategy to create complex microenvironments invitro that allow detailed studies on the interplay of topography, substrate surface properties, and soluble microenvironment on cellular fate processes. PMID:23781291

Biaxial deformation of collagen and elastin fibers in coronary adventitia

PubMed Central

Chen, Huan; Slipchenko, Mikhail N.; Liu, Yi; Zhao, Xuefeng; Cheng, Ji-Xin; Lanir, Yoram

2013-01-01

The microstructural deformation-mechanical loading relation of the blood vessel wall is essential for understanding the overall mechanical behavior of vascular tissue in health and disease. We employed simultaneous mechanical loading-imaging to quantify in situ deformation of individual collagen and elastin fibers on unstained fresh porcine coronary adventitia under a combination of vessel inflation and axial extension loading. Specifically, the specimens were imaged under biaxial loads to study microscopic deformation-loading behavior of fibers in conjunction with morphometric measurements at the zero-stress state. Collagen fibers largely orientate in the longitudinal direction, while elastin fibers have major orientation parallel to collagen, but with additional orientation angles in each sublayer of the adventitia. With an increase of biaxial load, collagen fibers were uniformly stretched to the loading direction, while elastin fibers gradually formed a network in sublayers, which strongly depended on the initial arrangement. The waviness of collagen decreased more rapidly at a circumferential stretch ratio of λθ = 1.0 than at λθ = 1.5, while most collagen became straightened at λθ = 1.8. These microscopic deformations imply that the longitudinally stiffer adventitia is a direct result of initial fiber alignment, and the overall mechanical behavior of the tissue is highly dependent on the corresponding microscopic deformation of fibers. The microstructural deformation-loading relation will serve as a foundation for micromechanical models of the vessel wall. PMID:24092692

Aligned 1-D nanorods of a π-gelator exhibit molecular orientation and excitation energy transport different from entangled fiber networks.

PubMed

Sakakibara, Keita; Chithra, Parayalil; Das, Bidisa; Mori, Taizo; Akada, Misaho; Labuta, Jan; Tsuruoka, Tohru; Maji, Subrata; Furumi, Seiichi; Shrestha, Lok Kumar; Hill, Jonathan P; Acharya, Somobrata; Ariga, Katsuhiko; Ajayaghosh, Ayyappanpillai

2014-06-18

Linear π-gelators self-assemble into entangled fibers in which the molecules are arranged perpendicular to the fiber long axis. However, orientation of gelator molecules in a direction parallel to the long axes of the one-dimensional (1-D) structures remains challenging. Herein we demonstrate that, at the air-water interface, an oligo(p-phenylenevinylene)-derived π-gelator forms aligned nanorods of 340 ± 120 nm length and 34 ± 5 nm width, in which the gelator molecules are reoriented parallel to the long axis of the rods. The orientation change of the molecules results in distinct excited-state properties upon local photoexcitation, as evidenced by near-field scanning optical microscopy. A detailed understanding of the mechanism by which excitation energy migrates through these 1-D molecular assemblies might help in the design of supramolecular structures with improved charge-transport properties.

A probabilistic analysis of electrical equipment vulnerability to carbon fibers

NASA Technical Reports Server (NTRS)

Elber, W.

1980-01-01

The statistical problems of airborne carbon fibers falling onto electrical circuits were idealized and analyzed. The probability of making contact between randomly oriented finite length fibers and sets of parallel conductors with various spacings and lengths was developed theoretically. The probability of multiple fibers joining to bridge a single gap between conductors, or forming continuous networks is included. From these theoretical considerations, practical statistical analyses to assess the likelihood of causing electrical malfunctions was produced. The statistics obtained were confirmed by comparison with results of controlled experiments.

Drops spreading on flexible fibers

NASA Astrophysics Data System (ADS)

Somszor, Katarzyna; Boulogne, François; Sauret, Alban; Dressaire, Emilie; Stone, Howard

2015-11-01

Fibrous media are encountered in many engineered systems such as textile, paper and insulating materials. In most of these materials, fibers are randomly oriented and form a complex network in which drops of wetting liquid tend to accumulate at the nodes of the network. Here we investigate the role of the fiber flexibility on the spreading of a small volume of liquid on a pair of crossed flexible fibers. A drop of silicone oil is dispensed at the point of contact of the fibers and we characterize the liquid morphologies as we vary the volume of liquid, the angle between the fibers, and the length and bending modulus of the fibers. Drop morphologies previously reported for rigid fibers, i.e. a drop, a column and a mixed morphology, are also observed on flexible fibers with modified domains of existence. Moreover, at small inclination angles of the fibers, a new behavior is observed: the fibers bend and collapse. Depending on the volume, the liquid can adopt a column or a mixed morphology on the collapsed fibers. We rationalize our observations with a model based on energetic considerations. Our study suggests that the fiber flexibility adds a rich variety of behaviors that can be crucial for industrial applications.

Facile Fabrication of Electrically Conductive Low-Density Polyethylene/Carbon Fiber Tubes for Novel Smart Materials via Multiaxial Orientation.

PubMed

Li, Yijun; Nie, Min; Wang, Qi

2018-01-10

Electromechanical sensors are indispensable components in functional devices and robotics application. However, the fabrication of the sensors still maintains a challenging issue that high percolation threshold and easy failure of conductive network are derived from uniaxial orientation of conductive fillers in practical melt processing. Herein, we reported a facile fabrication method to prepare a multiaxial low-density polyethylene (LDPE)/carbon fibers (CFs) tube with bidirectional controllable electrical conductivity and sensitive strain-responsive performance via rotation extrusion technology. The multidimensional helical flow is confirmed in the reverse rotation extrusion, and the CFs readily respond to the flow field leading to a multiaxial orientation in the LDPE matrix. In contrast to uniaxial LDPE/CF composites, which perform a "head to head" conjunction, multiaxial-orientated CF networks exhibit a unique multilayer structure in which the CFs with distinct orientation direction intersect in the interface, endowing the LDPE/CF composites with a low percolation threshold (15 wt %) to those of the uniaxial ones (∼35 wt %). The angles between two axes play a vital role in determining the density of the conductive networks in the interface, which is predominant in tuning the bending-responsive behaviors with a gauge factor range from 12.5 to 56.3 and the corresponding linear respond region from ∼15 to ∼1%. Such a superior performance of conductive LDPE/CF tube confirms that the design of multiaxial orientation paves a novel way to facile fabrication of advanced cost-effective CF-based smart materials, shedding light on promising applications such as smart materials and intelligent engineering monitoring.

Functionality in Electrospun Nanofibrous Membranes Based on Fiber's Size, Surface Area, and Molecular Orientation

PubMed Central

Matsumoto, Hidetoshi; Tanioka, Akihiko

2011-01-01

Electrospinning is a versatile method for forming continuous thin fibers based on an electrohydrodynamic process. This method has the following advantages: (i) the ability to produce thin fibers with diameters in the micrometer and nanometer ranges; (ii) one-step forming of the two- or three-dimensional nanofiber network assemblies (nanofibrous membranes); and (iii) applicability for a broad spectrum of molecules, such as synthetic and biological polymers and polymerless sol-gel systems. Electrospun nanofibrous membranes have received significant attention in terms of their practical applications. The major advantages of nanofibers or nanofibrous membranes are the functionalities based on their nanoscaled-size, highly specific surface area, and highly molecular orientation. These functionalities of the nanofibrous membranes can be controlled by their fiber diameter, surface chemistry and topology, and internal structure of the nanofibers. This report focuses on our studies and describes fundamental aspects and applications of electrospun nanofibrous membranes. PMID:24957735

TRACTOGRAPHY DENSITY AND NETWORK MEASURES IN ALZHEIMER'S DISEASE.

PubMed

Prasad, Gautam; Nir, Talia M; Toga, Arthur W; Thompson, Paul M

2013-04-01

Brain connectivity declines in Alzheimer's disease (AD), both functionally and structurally. Connectivity maps and networks derived from diffusion-based tractography offer new ways to track disease progression and to understand how AD affects the brain. Here we set out to identify (1) which fiber network measures show greatest differences between AD patients and controls, and (2) how these effects depend on the density of fibers extracted by the tractography algorithm. We computed brain networks from diffusion-weighted images (DWI) of the brain, in 110 subjects (28 normal elderly, 56 with early and 11 with late mild cognitive impairment, and 15 with AD). We derived connectivity matrices and network topology measures, for each subject, from whole-brain tractography and cortical parcellations. We used an ODF lookup table to speed up fiber extraction, and to exploit the full information in the orientation distribution function (ODF). This made it feasible to compute high density connectivity maps. We used accelerated tractography to compute a large number of fibers to understand what effect fiber density has on network measures and in distinguishing different disease groups in our data. We focused on global efficiency, transitivity, path length, mean degree, density, modularity, small world, and assortativity measures computed from weighted and binary undirected connectivity matrices. Of all these measures, the mean nodal degree best distinguished diagnostic groups. High-density fiber matrices were most helpful for picking up the more subtle clinical differences, e.g. between mild cognitively impaired (MCI) and normals, or for distinguishing subtypes of MCI (early versus late). Care is needed in clinical analyses of brain connectivity, as the density of extracted fibers may affect how well a network measure can pick up differences between patients and controls.

Metropolitian area network services comprised of virtual local area networks running over hybrid fiber-coax and asynchronous transfer mode technologies

NASA Astrophysics Data System (ADS)

Biedron, William S.

1995-11-01

Since 1990 there has been a rapid increase in the demand for communication services, especially local and wide area network (LAN/WAN) oriented services. With the introduction of the DFB laser transmitter, hybrid-fiber-coax (HFC) cable plant designs, ATM transport technologies and rf modems, new LAN/WAN services can now be defined and marketed to residential and business customers over existing cable TV systems. The term metropolitan area network (MAN) can be used to describe this overall network. This paper discusses the technical components needed to provision these services as well as provides some perspectives on integration issues. Architecture at the headend and in the backbone is discussed, as well as specific service definitions and the technology issues associated with each. The TCP/IP protocol is suggested as a primary protocol to be used throughout the MAN.

Bio-inspired dental fillings

NASA Astrophysics Data System (ADS)

Deyhle, Hans; Bunk, Oliver; Buser, Stefan; Krastl, Gabriel; Zitzmann, Nicola U.; Ilgenstein, Bernd; Beckmann, Felix; Pfeiffer, Franz; Weiger, Roland; Müller, Bert

2009-08-01

Human teeth are anisotropic composites. Dentin as the core material of the tooth consists of nanometer-sized calcium phosphate crystallites embedded in collagen fiber networks. It shows its anisotropy on the micrometer scale by its well-oriented microtubules. The detailed three-dimensional nanostructure of the hard tissues namely dentin and enamel, however, is not understood, although numerous studies on the anisotropic mechanical properties have been performed and evaluated to explain the tooth function including the enamel-dentin junction acting as effective crack barrier. Small angle X-ray scattering (SAXS) with a spatial resolution in the 10 μm range allows determining the size and orientation of the constituents on the nanometer scale with reasonable precision. So far, only some dental materials, i.e. the fiber reinforced posts exhibit anisotropic properties related to the micrometer-size glass fibers. Dental fillings, composed of nanostructures oriented similar to the natural hard tissues of teeth, however, do not exist at all. The current X-ray-based investigations of extracted human teeth provide evidence for oriented micro- and nanostructures in dentin and enamel. These fundamental quantitative findings result in profound knowledge to develop biologically inspired dental fillings with superior resistance to thermal and mechanical shocks.

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials.

PubMed

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-12

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis.

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials

PubMed Central

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-01

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis. PMID:28787839

Fiber/collagen composites for ligament tissue engineering: influence of elastic moduli of sparse aligned fibers on mesenchymal stem cells.

PubMed

Thayer, Patrick S; Verbridge, Scott S; Dahlgren, Linda A; Kakar, Sanjeev; Guelcher, Scott A; Goldstein, Aaron S

2016-08-01

Electrospun microfibers are attractive for the engineering of oriented tissues because they present instructive topographic and mechanical cues to cells. However, high-density microfiber networks are too cell-impermeable for most tissue applications. Alternatively, the distribution of sparse microfibers within a three-dimensional hydrogel could present instructive cues to guide cell organization while not inhibiting cell behavior. In this study, thin (∼5 fibers thick) layers of aligned microfibers (0.7 μm) were embedded within collagen hydrogels containing mesenchymal stem cells (MSCs), cultured for up to 14 days, and assayed for expression of ligament markers and imaged for cell organization. These microfibers were generated through the electrospinning of polycaprolactone (PCL), poly(ester-urethane) (PEUR), or a 75/25 PEUR/PCL blend to produce microfiber networks with elastic moduli of 31, 15, and 5.6 MPa, respectively. MSCs in composites containing 5.6 MPa fibers exhibited increased expression of the ligament marker scleraxis and the contractile phenotype marker α-smooth muscle actin versus the stiffer fiber composites. Additionally, cells within the 5.6 MPa microfiber composites were more oriented compared to cells within the 15 and 31 MPa microfiber composites. Together, these data indicate that the mechanical properties of microfiber/collagen composites can be tuned for the engineering of ligament and other target tissues. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1894-1901, 2016. © 2016 Wiley Periodicals, Inc.

Using fiber networks to stimulate transit oriented development : prospects, barriers and best practices

DOT National Transportation Integrated Search

2001-10-01

This study empirically examines a practical aspect of a relationship that is only now being conceptualized--the relationship between rail transit, land development, and telecommunications. It pushes the envelope of knowledge in so far as the interact...

Using Fiber Networks to Stimulate Transit Oriented Development: Prospects, Barriers and Best Practices

DOT National Transportation Integrated Search

2001-10-01

This study empirically examines a practical aspect of a relationship that is only now being conceptualized--the relationship between rail transit, land development, and telecommunications. It pushes the envelope of knowledge in so far as the interact...

The spatial-temporal characteristics of type I collagen-based extracellular matrix.

PubMed

Jones, Christopher Allen Rucksack; Liang, Long; Lin, Daniel; Jiao, Yang; Sun, Bo

2014-11-28

Type I collagen abounds in mammalian extracellular matrix (ECM) and is crucial to many biophysical processes. While previous studies have mostly focused on bulk averaged properties, here we provide a comprehensive and quantitative spatial-temporal characterization of the microstructure of type I collagen-based ECM as the gelation temperature varies. The structural characteristics including the density and nematic correlation functions are obtained by analyzing confocal images of collagen gels prepared at a wide range of gelation temperatures (from 16 °C to 36 °C). As temperature increases, the gel microstructure varies from a "bundled" network with strong orientational correlation between the fibers to an isotropic homogeneous network with no significant orientational correlation, as manifested by the decaying of length scales in the correlation functions. We develop a kinetic Monte-Carlo collagen growth model to better understand how ECM microstructure depends on various environmental or kinetic factors. We show that the nucleation rate, growth rate, and an effective hydrodynamic alignment of collagen fibers fully determines the spatiotemporal fluctuations of the density and orientational order of collagen gel microstructure. Also the temperature dependence of the growth rate and nucleation rate follow the prediction of classical nucleation theory.

Glass-based integrated optical splitters: engineering oriented research

NASA Astrophysics Data System (ADS)

Hao, Yinlei; Zheng, Weiwei; Yang, Jianyi; Jiang, Xiaoqing; Wang, Minghua

2010-10-01

Optical splitter is one of most typical device heavily demanded in implementation of Fiber To The Home (FTTH) system. Due to its compatibility with optical fibers, low propagation loss, flexibility, and most distinguishingly, potentially costeffectiveness, glass-based integrated optical splitters made by ion-exchange technology promise to be very attractive in application of optical communication networks. Aiming at integrated optical splitters applied in optical communication network, glass ion-exchange waveguide process is developed, which includes two steps: thermal salts ion-exchange and field-assisted ion-diffusion. By this process, high performance optical splitters are fabricated in specially melted glass substrate. Main performance parameters of these splitters, including maximum insertion loss (IL), polarization dependence loss (PDL), and IL uniformity are all in accordance with corresponding specifications in generic requirements for optic branching components (GR-1209-CORE). In this paper, glass based integrated optical splitters manufacturing is demonstrated, after which, engineering-oriented research work results on glass-based optical splitter are presented.

From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials

PubMed Central

D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R.; Sacks, Michael S.

2014-01-01

In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. PMID:25128869

A three-dimensional collagen-fiber network model of the extracellular matrix for the simulation of the mechanical behaviors and micro structures.

PubMed

Dong, Shoubin; Huang, Zetao; Tang, Liqun; Zhang, Xiaoyang; Zhang, Yongrou; Jiang, Yi

2017-07-01

The extracellular matrix (ECM) provides structural and biochemical support to cells and tissues, which is a critical factor for modulating cell dynamic behavior and intercellular communication. In order to further understand the mechanisms of the interactive relationship between cell and the ECM, we developed a three-dimensional (3D) collagen-fiber network model to simulate the micro structure and mechanical behaviors of the ECM and studied the stress-strain relationship as well as the deformation of the ECM under tension. In the model, the collagen-fiber network consists of abundant random distributed collagen fibers and some crosslinks, in which each fiber is modeled as an elastic beam and a crosslink is modeled as a linear spring with tensile limit, it means crosslinks will fail while the tensile forces exceed the limit of spring. With the given parameters of the beam and the spring, the simulated tensile stress-strain relation of the ECM highly matches the experimental results including damaged and failed behaviors. Moreover, by applying the maximal inscribed sphere method, we measured the size distribution of pores in the fiber network and learned the variation of the distribution with deformation. We also defined the alignment of the collagen-fibers to depict the orientation of fibers in the ECM quantitatively. By the study of changes of the alignment and the damaged crosslinks against the tensile strain, this paper reveals the comprehensive mechanisms of four stages of 'toe', 'linear', 'damage' and 'failure' in the tensile stress-strain relation of the ECM which can provide further insight in the study of cell-ECM interaction.

Consensus between Pipelines in Structural Brain Networks

PubMed Central

Parker, Christopher S.; Deligianni, Fani; Cardoso, M. Jorge; Daga, Pankaj; Modat, Marc; Dayan, Michael; Clark, Chris A.

2014-01-01

Structural brain networks may be reconstructed from diffusion MRI tractography data and have great potential to further our understanding of the topological organisation of brain structure in health and disease. Network reconstruction is complex and involves a series of processesing methods including anatomical parcellation, registration, fiber orientation estimation and whole-brain fiber tractography. Methodological choices at each stage can affect the anatomical accuracy and graph theoretical properties of the reconstructed networks, meaning applying different combinations in a network reconstruction pipeline may produce substantially different networks. Furthermore, the choice of which connections are considered important is unclear. In this study, we assessed the similarity between structural networks obtained using two independent state-of-the-art reconstruction pipelines. We aimed to quantify network similarity and identify the core connections emerging most robustly in both pipelines. Similarity of network connections was compared between pipelines employing different atlases by merging parcels to a common and equivalent node scale. We found a high agreement between the networks across a range of fiber density thresholds. In addition, we identified a robust core of highly connected regions coinciding with a peak in similarity across network density thresholds, and replicated these results with atlases at different node scales. The binary network properties of these core connections were similar between pipelines but showed some differences in atlases across node scales. This study demonstrates the utility of applying multiple structural network reconstrution pipelines to diffusion data in order to identify the most important connections for further study. PMID:25356977

Simulated remodeling of loaded collagen networks via strain-dependent enzymatic degradation and constant-rate fiber growth

PubMed Central

Hadi, M.F.; Sander, E.A.; Ruberti, J.W.; Barocas, V. H.

2011-01-01

Recent work has demonstrated that enzymatic degradation of collagen fibers exhibits strain-dependent kinetics. Conceptualizing how the strain dependence affects remodeling of collagenous tissues is vital to our understanding of collagen management in native and bioengineered tissues. As a first step towards this goal, the current study puts forward a multiscale model for enzymatic degradation and remodeling of collagen networks for two sample geometries we routinely use in experiments as model tissues. The multiscale model, driven by microstructural data from an enzymatic decay experiment, includes an exponential strain-dependent kinetic relation for degradation and constant growth. For a dogbone sample under uniaxial load, the model predicted that the distribution of fiber diameters would spread over the course of degradation because of variation in individual fiber load. In a cross-shaped sample, the central region, which experiences smaller, more isotropic loads, showed more decay and less spread in fiber diameter compared to the arms. There was also a slight shift in average orientation in different regions of the cruciform. PMID:22180691

Registering myocardial fiber orientations with heart geometry using iterative closest points algorithms

NASA Astrophysics Data System (ADS)

Deng, Dongdong; Jiao, Peifeng; Shou, Guofa; Xia, Ling

2009-10-01

Myocardial electrical excitation propagation is anisotropic, with the most rapid spread of current along the direction of the long axis of the fiber. Fiber orientation is also an important determinant of myocardial mechanics. So myocardial fiber orientations are very important to heart modeling and simulation. Accurately construction of myocardial fiber orientations, however, is still a challenge. The purpose of this paper is to construct a heart geometrical model with myocardial fiber orientations based on CT and 3D laser scanned pictures. The iterative closest points (ICP) algorithms were used to register the fiber orientations with the heart geometry.

Influence of Fiber Orientation on Single-Point Cutting Fracture Behavior of Carbon-Fiber/Epoxy Prepreg Sheets.

PubMed

Wei, Yingying; An, Qinglong; Cai, Xiaojiang; Chen, Ming; Ming, Weiwei

2015-10-02

The purpose of this article is to investigate the influences of carbon fibers on the fracture mechanism of carbon fibers both in macroscopic view and microscopic view by using single-point flying cutting method. Cutting tools with three different materials were used in this research, namely, PCD (polycrystalline diamond) tool, CVD (chemical vapor deposition) diamond thin film coated carbide tool and uncoated carbide tool. The influence of fiber orientation on the cutting force and fracture topography were analyzed and conclusions were drawn that cutting forces are not affected by cutting speeds but significantly influenced by the fiber orientation. Cutting forces presented smaller values in the fiber orientation of 0/180° and 15/165° but the highest one in 30/150°. The fracture mechanism of carbon fibers was studied in different cutting conditions such as 0° orientation angle, 90° orientation angle, orientation angles along fiber direction, and orientation angles inverse to the fiber direction. In addition, a prediction model on the cutting defects of carbon fiber reinforced plastic was established based on acoustic emission (AE) signals.

Influence of Fiber Orientation on Single-Point Cutting Fracture Behavior of Carbon-Fiber/Epoxy Prepreg Sheets

PubMed Central

Wei, Yingying; An, Qinglong; Cai, Xiaojiang; Chen, Ming; Ming, Weiwei

2015-01-01

The purpose of this article is to investigate the influences of carbon fibers on the fracture mechanism of carbon fibers both in macroscopic view and microscopic view by using single-point flying cutting method. Cutting tools with three different materials were used in this research, namely, PCD (polycrystalline diamond) tool, CVD (chemical vapor deposition) diamond thin film coated carbide tool and uncoated carbide tool. The influence of fiber orientation on the cutting force and fracture topography were analyzed and conclusions were drawn that cutting forces are not affected by cutting speeds but significantly influenced by the fiber orientation. Cutting forces presented smaller values in the fiber orientation of 0/180° and 15/165° but the highest one in 30/150°. The fracture mechanism of carbon fibers was studied in different cutting conditions such as 0° orientation angle, 90° orientation angle, orientation angles along fiber direction, and orientation angles inverse to the fiber direction. In addition, a prediction model on the cutting defects of carbon fiber reinforced plastic was established based on acoustic emission (AE) signals. PMID:28793597

Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thi, Thanh Binh Nguyen, E-mail: nttbinh@kit.ac.jp; Yokoyama, Atsushi, E-mail: yokoyama@kit.ac.jp; Hamanaka, Senji

The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavitymore » geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement and confirm the basic understanding of fiber orientation in injection-molded composites.« less

Numerical simulation of fiber interaction in short-fiber injection-molded composite using different cavity geometries

NASA Astrophysics Data System (ADS)

Thi, Thanh Binh Nguyen; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

2016-03-01

The theoretical fiber-interaction model for calculating the fiber orientation in the injection molded short fiber/thermoplastic composite parts was proposed. The proposed model included the fiber dynamics simulation in order to obtain an equation of the global interaction coefficient and accurate estimate of the fiber interacts at all orientation states. The steps to derive the equation for this coefficient in short fiber suspension as a function of the fiber aspect ratio, volume fraction and general shear rate are delineated. Simultaneously, the high-resolution 3D X-ray computed tomography system XVA-160α was used to observe fiber distribution of short-glass-fiber-reinforced polyamide specimens using different cavity geometries. The fiber orientation tensor components are then calculated. Experimental orientation measurements of short-glass-fiber-reinforced polyamide is used to check the ability of present theory for predicting orientation. The experiments and predictions show a quantitative agreement and confirm the basic understanding of fiber orientation in injection-molded composites.

Structures with high number density of carbon nanotubes and 3-dimensional distribution

NASA Technical Reports Server (NTRS)

Chen, Zheng (Inventor); Tzeng, Yonhua (Inventor)

2002-01-01

A composite is described having a three dimensional distribution of carbon nanotubes. The critical aspect of such composites is a nonwoven network of randomly oriented fibers connected at their junctions to afford macropores in the spaces between the fibers. A variety of fibers may be employed, including metallic fibers, and especially nickel fibers. The composite has quite desirable properties for cold field electron emission applications, such as a relatively low turn-on electric field, high electric field enhancement factors, and high current densities. The composites of this invention also show favorable properties for other an electrode applications. Several methods, which also have general application in carbon nanotube production, of preparing these composites are described and employ a liquid feedstock of oxyhydrocarbons as carbon nanotube precursors.

FIBER ORIENTATION IN INJECTION MOLDED LONG CARBON FIBER THERMOPLASTIC COMPOSITES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jin; Nguyen, Ba Nghiep; Mathur, Raj N.

2015-03-23

A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the anisotropic rotary diffusion and the reduced strain closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.

A Structural Finite Element Model for Lamellar Unit of Aortic Media Indicates Heterogeneous Stress Field After Collagen Recruitment

PubMed Central

Thunes, James R.; Pal, Siladitya; Fortunato, Ronald N.; Phillippi, Julie A.; Gleason, Thomas G.; Vorp, David A.; Maiti, Spandan

2016-01-01

Incorporation of collagen structural information into the study of biomechanical behavior of ascending thoracic aortic (ATA) wall tissue should provide better insight into the pathophysiology of ATA. Structurally motivated constitutive models that include fiber dispersion and recruitment can successfully capture overall mechanical response of the arterial wall tissue. However, these models cannot examine local microarchitectural features of the collagen network, such as the effect of fiber disruptions and interaction between fibrous and non-fibrous components, which may influence emergent biomechanical properties of the tissue. Motivated by this need, we developed a finite element based three-dimensional structural model of the lamellar units of the ATA media that directly incorporates the collagen fiber microarchitecture. The fiber architecture was computer generated utilizing network features, namely fiber orientation distribution, intersection density and areal concentration, obtained from image analysis of multiphoton microscopy images taken from human aneurysmal ascending thoracic aortic media specimens with bicuspid aortic valve (BAV) phenotype. Our model reproduces the typical J-shaped constitutive response of the aortic wall tissue. We found that the stress state in the non-fibrous matrix was homogeneous until the collagen fibers were recruited, but became highly heterogeneous after that event. The degree of heterogeneity was dependent upon local network architecture with high stresses observed near disrupted fibers. The magnitude of non-fibrous matrix stress at higher stretch levels was negatively correlated with local fiber density. The localized stress concentrations, elucidated by this model, may be a factor in the degenerative changes in aneurysmal ATA tissue. PMID:27113538

Modeling of fiber orientation in viscous fluid flow with application to self-compacting concrete

NASA Astrophysics Data System (ADS)

Kolařík, Filip; Patzák, Bořek

2013-10-01

In recent years, unconventional concrete reinforcement is of growing popularity. Especially fiber reinforcement has very wide usage in high performance concretes like "Self Compacting Concrete" (SCC). The design of advanced tailor-made structures made of SCC can take advantage of anisotropic orientation of fibers. Tools for fiber orientation predictions can contribute to design of tailor made structure and allow to develop casting procedures that enable to achieve the desired fiber distribution and orientation. This paper deals with development and implementation of suitable tool for prediction of fiber orientation in a fluid based on the knowledge of the velocity field. Statistical approach to the topic is employed. Fiber orientation is described by a probability distribution of the fiber angle.

Polarized light microscopy for 3-dimensional mapping of collagen fiber architecture in ocular tissues.

PubMed

Yang, Bin; Jan, Ning-Jiun; Brazile, Bryn; Voorhees, Andrew; Lathrop, Kira L; Sigal, Ian A

2018-04-06

Collagen fibers play a central role in normal eye mechanics and pathology. In ocular tissues, collagen fibers exhibit a complex 3-dimensional (3D) fiber orientation, with both in-plane (IP) and out-of-plane (OP) orientations. Imaging techniques traditionally applied to the study of ocular tissues only quantify IP fiber orientation, providing little information on OP fiber orientation. Accurate description of the complex 3D fiber microstructures of the eye requires quantifying full 3D fiber orientation. Herein, we present 3dPLM, a technique based on polarized light microscopy developed to quantify both IP and OP collagen fiber orientations of ocular tissues. The performance of 3dPLM was examined by simulation and experimental verification and validation. The experiments demonstrated an excellent agreement between extracted and true 3D fiber orientation. Both IP and OP fiber orientations can be extracted from the sclera and the cornea, providing previously unavailable quantitative 3D measures and insight into the tissue microarchitecture. Together, the results demonstrate that 3dPLM is a powerful imaging technique for the analysis of ocular tissues. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

From single fiber to macro-level mechanics: A structural finite-element model for elastomeric fibrous biomaterials.

PubMed

D'Amore, Antonio; Amoroso, Nicholas; Gottardi, Riccardo; Hobson, Christopher; Carruthers, Christopher; Watkins, Simon; Wagner, William R; Sacks, Michael S

2014-11-01

In the present work, we demonstrate that the mesoscopic in-plane mechanical behavior of membrane elastomeric scaffolds can be simulated by replication of actual quantified fibrous geometries. Elastomeric electrospun polyurethane (ES-PEUU) scaffolds, with and without particulate inclusions, were utilized. Simulations were developed from experimentally-derived fiber network geometries, based on a range of scaffold isotropic and anisotropic behaviors. These were chosen to evaluate the effects on macro-mechanics based on measurable geometric parameters such as fiber intersections, connectivity, orientation, and diameter. Simulations were conducted with only the fiber material model parameters adjusted to match the macro-level mechanical test data. Fiber model validation was performed at the microscopic level by individual fiber mechanical tests using AFM. Results demonstrated very good agreement to the experimental data, and revealed the formation of extended preferential fiber orientations spanning the entire model space. We speculate that these emergent structures may be responsible for the tissue-like macroscale behaviors observed in electrospun scaffolds. To conclude, the modeling approach has implications for (1) gaining insight on the intricate relationship between fabrication variables, structure, and mechanics to manufacture more functional devices/materials, (2) elucidating the effects of cell or particulate inclusions on global construct mechanics, and (3) fabricating better performing tissue surrogates that could recapitulate native tissue mechanics. Copyright © 2014 Elsevier Ltd. All rights reserved.

Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey’s equation a diffusive type of term by introducing amore » phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29{sup th} International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.« less

Numerical prediction of fiber orientation in injection-molded short-fiber/thermoplastic composite parts with experimental validation

NASA Astrophysics Data System (ADS)

Thi, Thanh Binh Nguyen; Morioka, Mizuki; Yokoyama, Atsushi; Hamanaka, Senji; Yamashita, Katsuhisa; Nonomura, Chisato

2015-05-01

Numerical prediction of the fiber orientation in the short-glass fiber (GF) reinforced polyamide 6 (PA6) composites with the fiber weight concentration of 30%, 50%, and 70% manufactured by the injection molding process is presented. And the fiber orientation was also directly observed and measured through X-ray computed tomography. During the injection molding process of the short-fiber/thermoplastic composite, the fiber orientation is produced by the flow states and the fiber-fiber interaction. Folgar and Tucker equation is the well known for modeling the fiber orientation in a concentrated suspension. They included into Jeffrey's equation a diffusive type of term by introducing a phenomenological coefficient to account for the fiber-fiber interaction. Our developed model for the fiber-fiber interaction was proposed by modifying the rotary diffusion term of the Folgar-Tucker equation. This model was presented in a conference paper of the 29th International Conference of the Polymer Processing Society published by AIP conference proceeding. For modeling fiber interaction, the fiber dynamic simulation was introduced in order to obtain a global fiber interaction coefficient, which is sum function of the fiber concentration, aspect ratio, and angular velocity. The fiber orientation is predicted by using the proposed fiber interaction model incorporated into a computer aided engineering simulation package C-Mold. An experimental program has been carried out in which the fiber orientation distribution has been measured in 100 x 100 x 2 mm injection-molded plate and 100 x 80 x 2 mm injection-molded weld by analyzed with a high resolution 3D X-ray computed tomography system XVA-160α, and calculated by X-ray computed tomography imaging. The numerical prediction shows a good agreement with experimental validation. And the complex fiber orientation in the injection-molded weld was investigated.

Fiber estimation and tractography in diffusion MRI: development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values.

PubMed

Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

2015-04-01

Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, tractography and the ability to recover complex white-matter pathways, differences between results due to choice of analysis method, and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work, we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment "ball and stick" model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm(2)) common to clinical studies. We found that the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of fibers. Fiber detection rate was found to be the most distinguishing characteristic between the methods, and a significant factor for complete recovery of tractography through complex white-matter pathways. For example, while all methods recovered similar tractography of prominent white matter pathways of limited fiber crossing, CSD (which had the highest fiber detection rate, especially for voxels containing three fibers) recovered the greatest number of fibers and largest fraction of correct tractography for complex three-fiber crossing regions. The synthetic data sets, ground-truth, and tools for quantitative evaluation are publically available on the NITRC website as the project "Simulated DW-MRI Brain Data Sets for Quantitative Evaluation of Estimated Fiber Orientations" at http://www.nitrc.org/projects/sim_dwi_brain. Copyright © 2014 Elsevier Inc. All rights reserved.

Development of eddy current probe for fiber orientation assessment in carbon fiber composites

NASA Astrophysics Data System (ADS)

Wincheski, Russell A.; Zhao, Selina

2018-04-01

Measurement of the fiber orientation in a carbon fiber composite material is crucial in understanding the load carrying capability of the structure. As manufacturing conditions including resin flow and molding pressures can alter fiber orientation, verification of the as-designed fiber layup is necessary to ensure optimal performance of the structure. In this work, the development of an eddy current probe and data processing technique for analysis of fiber orientation in carbon fiber composites is presented. A proposed directional eddy current probe is modeled and its response to an anisotropic multi-layer conductor simulated. The modeling results are then used to finalize specifications of the eddy current probe. Experimental testing of the fabricated probe is presented for several samples including a truncated pyramid part with complex fiber orientation draped to the geometry for resin transfer molding. The inductively coupled single sided measurement enables fiber orientation characterization through the thickness of the part. The fast and cost-effective technique can be applied as a spot check or as a surface map of the fiber orientations across the structure. This paper will detail the results of the probe design, computer simulations, and experimental results.

Probing molecular orientation of P3HT nanofibers in fiber-based organic solar cells

NASA Astrophysics Data System (ADS)

Yoon, Sangcheol; Han, Yaeeun; Hwang, Inchan

2018-01-01

Molecular orientation of conjugated polymers plays a key role in exciton generation/separation and charge transport, and thus significantly influence photovoltaic devices. Herein, we fabricated fiber-based organic solar cells and investigated the photovoltaic parameters with different diameters of fibers and PCBM diffusion. The open-circuit voltage that varies with molecular orientation whether it is face-on or edge-on was observed to differ. The investigation of the open-circuit voltage dependence reveals that thick fibers have core/shell like structures with different orientations. Thick fibers have face-on in the core and edge-on orientations in the shell. The face-on orientations are not preferentially formed in thin fibers, but the PCBM diffusion can induce face-on orientations that exist within the intermixed phase. Our results may shed a light on better understanding on fiber-based solar cells and suggest a way toward improving photovoltaic efficiency. [Figure not available: see fulltext.

A fiber orientation-adapted integration scheme for computing the hyperelastic Tucker average for short fiber reinforced composites

NASA Astrophysics Data System (ADS)

Goldberg, Niels; Ospald, Felix; Schneider, Matti

2017-10-01

In this article we introduce a fiber orientation-adapted integration scheme for Tucker's orientation averaging procedure applied to non-linear material laws, based on angular central Gaussian fiber orientation distributions. This method is stable w.r.t. fiber orientations degenerating into planar states and enables the construction of orthotropic hyperelastic energies for truly orthotropic fiber orientation states. We establish a reference scenario for fitting the Tucker average of a transversely isotropic hyperelastic energy, corresponding to a uni-directional fiber orientation, to microstructural simulations, obtained by FFT-based computational homogenization of neo-Hookean constituents. We carefully discuss ideas for accelerating the identification process, leading to a tremendous speed-up compared to a naive approach. The resulting hyperelastic material map turns out to be surprisingly accurate, simple to integrate in commercial finite element codes and fast in its execution. We demonstrate the capabilities of the extracted model by a finite element analysis of a fiber reinforced chain link.

Combining flagelliform and dragline spider silk motifs to produce tunable synthetic biopolymer fibers.

PubMed

Teulé, Florence; Addison, Bennett; Cooper, Alyssa R; Ayon, Joel; Henning, Robert W; Benmore, Chris J; Holland, Gregory P; Yarger, Jeffery L; Lewis, Randolph V

2012-06-01

The two Flag/MaSp 2 silk proteins produced recombinantly were based on the basic consensus repeat of the dragline silk spidroin 2 protein (MaSp 2) from the Nephila clavipes orb weaving spider. However, the proline-containing pentapeptides juxtaposed to the polyalanine segments resembled those found in the flagelliform silk protein (Flag) composing the web spiral: (GPGGX(1) GPGGX(2))(2) with X(1) /X(2) = A/A or Y/S. Fibers were formed from protein films in aqueous solutions or extruded from resolubilized protein dopes in organic conditions when the Flag motif was (GPGGX(1) GPGGX(2))(2) with X(1) /X(2) = Y/S or A/A, respectively. Post-fiber processing involved similar drawing ratios (2-2.5×) before or after water-treatment. Structural (ssNMR and XRD) and morphological (SEM) changes in the fibers were compared to the mechanical properties of the fibers at each step. Nuclear magnetic resonance indicated that the fraction of β-sheet nanocrystals in the polyalanine regions formed upon extrusion, increased during stretching, and was maximized after water-treatment. X-ray diffraction showed that nanocrystallite orientation parallel to the fiber axis increased the ultimate strength and initial stiffness of the fibers. Water furthered nanocrystal orientation and three-dimensional growth while plasticizing the amorphous regions, thus producing tougher fibers due to increased extensibility. These fibers were highly hygroscopic and had similar internal network organization, thus similar range of mechanical properties that depended on their diameters. The overall structure of the consensus repeat of the silk-like protein dictated the mechanical properties of the fibers while protein molecular weight limited these same properties. Subtle structural motif re-design impacted protein self-assembly mechanisms and requirements for fiber formation. Copyright © 2011 Wiley Periodicals, Inc.

Combining flagelliform and dragline spider silk motifs to produce tunable synthetic biopolymer fibers

PubMed Central

Teulé, Florence; Addison, Bennett; Cooper, Alyssa R.; Ayon, Joel; Henning, Robert W.; Benmore, Chris J.; Holland, Gregory P.; Yarger, Jeffery L.; Lewis, Randolph V.

2012-01-01

The two Flag/MaSp 2 silk proteins produced recombinantly were based on the basic consensus repeat of the dragline silk spidroin 2 protein (MaSp 2) from the Nephila clavipes orb weaving spider. However, the proline-containing pentaptides juxtaposed to the polyalanine segments resembled those found in the flagelliform silk protein (Flag) composing the web spiral: (GPGGX1 GPGGX2)2 with X1/X2=A/A or Y/S. Fibers were formed from protein films in aqueous solutions or extruded from resolubilized protein dopes in organic conditions when the Flag motif was (GPGGX1 GPGGX2)2 with X1/X2 = Y/S or A/A, respectively. Post fiber processing involved similar drawing ratios (2–2.5×) before or after water-treatment. Structural (ssNMR and XRD) and morphological (SEM) changes in the fibers were compared to the mechanical properties of the fibers at each step. NMR indicated that the fraction of β-sheet nanocrystals in the polyalanine regions formed upon extrusion, increased during stretching, and was maximized after water-treatment. XRD showed that nanocrystallite orientation parallel to the fiber axis increased the ultimate strength and initial stiffness of the fibers. Water furthered nanocrystal orientation and three-dimensional growth while plasticizing the amorphous regions, thus producing tougher fibers due to increased extensibility. These fibers were highly hygroscopic and had similar internal network organization, thus similar range of mechanical properties that depended on their diameters. The overall structure of the consensus repeat of the silk-like protein dictated the mechanical properties of the fibers while protein molecular weight limited these same properties. Subtle structural motif redesign impacted protein self-assembly mechanisms and requirements for fiber formation. PMID:22012252

Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Aslam, Muhammad, E-mail: klaira73@gmail.com; Altaf, Khurram, E-mail: khurram.altaf@petronas.com.my

2015-07-22

Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Randommore » orientation of fibers was noted in the composites test bars produced from divergent melt flow.« less

Effect of fiber orientation on tensile and impact properties of Zalacca Midrib fiber-HDPE composites by compression molding

NASA Astrophysics Data System (ADS)

Lasikun, Ariawan, Dody; Surojo, Eko; Triyono, Joko

2018-02-01

The research aims to investigate the fiber orientation effect on the tensile and impact properties of zalacca midrib fiber /HDPE composites. The composites were produced by compression molding with pressing temperature at 150°C, pressing pressure at 50 bar, and holding time of 25 minutes. The fiber orientations applied in composites were 0°, 15°, 30°, 45°, 60°, 75°, and 90°, at 10% fiber volume fraction. The samples were evaluated by using: Tensile test and Izod impact test according to ASTM D638 and ASTM D5941, respectively. The result of experiments indicate that the orientation of zalacca midrib fiber influences the characteristics of HDPE composite-zalacca midrib fiber. The composite mechanical strength decline with the increase of orientation fibers from 0° to 90°. The composite failure mode of composites are observed by Scanning Electron Microscope (SEM).

Effective Young's modulus of bacterial and microfibrillated cellulose fibrils in fibrous networks.

PubMed

Tanpichai, Supachok; Quero, Franck; Nogi, Masaya; Yano, Hiroyuki; Young, Robert J; Lindström, Tom; Sampson, William W; Eichhorn, Stephen J

2012-05-14

The deformation micromechanics of bacterial cellulose (BC) and microfibrillated cellulose (MFC) networks have been investigated using Raman spectroscopy. The Raman spectra of both BC and MFC networks exhibit a band initially located at ≈ 1095 cm(-1). We have used the intensity of this band as a function of rotation angle of the specimens to study the cellulose fibril orientation in BC and MFC networks. We have also used the change in this peak's wavenumber position with applied tensile deformation to probe the stress-transfer behavior of these cellulosic materials. The intensity of this Raman band did not change significantly with rotation angle, indicating an in-plane 2D network of fibrils with uniform random orientation; conversely, a highly oriented flax fiber exhibited a marked change in intensity with rotation angle. Experimental data and theoretical analysis shows that the Raman band shift rate arising from deformation of networks under tension is dependent on the angles between the axis of fibrils, the strain axis, the incident laser polarization direction, and the back scattered polarization configurations. From this analysis, the effective moduli of single fibrils of BC and MFC in the networks were estimated to be in the ranges of 79-88 and 29-36 GPa, respectively. It is shown also that for the model to fit the data it is necessary to use a negative Poisson's ratio for MFC networks and BC networks. Discussion of this in-plane "auxetic" behavior is given.

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

NASA Astrophysics Data System (ADS)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-06-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

NASA Astrophysics Data System (ADS)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-04-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Sparse Bayesian Inference of White Matter Fiber Orientations from Compressed Multi-resolution Diffusion MRI

PubMed Central

Pisharady, Pramod Kumar; Duarte-Carvajalino, Julio M; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2017-01-01

The RubiX [1] algorithm combines high SNR characteristics of low resolution data with high spacial specificity of high resolution data, to extract microstructural tissue parameters from diffusion MRI. In this paper we focus on estimating crossing fiber orientations and introduce sparsity to the RubiX algorithm, making it suitable for reconstruction from compressed (under-sampled) data. We propose a sparse Bayesian algorithm for estimation of fiber orientations and volume fractions from compressed diffusion MRI. The data at high resolution is modeled using a parametric spherical deconvolution approach and represented using a dictionary created with the exponential decay components along different possible directions. Volume fractions of fibers along these orientations define the dictionary weights. The data at low resolution is modeled using a spatial partial volume representation. The proposed dictionary representation and sparsity priors consider the dependence between fiber orientations and the spatial redundancy in data representation. Our method exploits the sparsity of fiber orientations, therefore facilitating inference from under-sampled data. Experimental results show improved accuracy and decreased uncertainty in fiber orientation estimates. For under-sampled data, the proposed method is also shown to produce more robust estimates of fiber orientations. PMID:28845484

Sparse Bayesian Inference of White Matter Fiber Orientations from Compressed Multi-resolution Diffusion MRI.

PubMed

Pisharady, Pramod Kumar; Duarte-Carvajalino, Julio M; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2015-10-01

The RubiX [1] algorithm combines high SNR characteristics of low resolution data with high spacial specificity of high resolution data, to extract microstructural tissue parameters from diffusion MRI. In this paper we focus on estimating crossing fiber orientations and introduce sparsity to the RubiX algorithm, making it suitable for reconstruction from compressed (under-sampled) data. We propose a sparse Bayesian algorithm for estimation of fiber orientations and volume fractions from compressed diffusion MRI. The data at high resolution is modeled using a parametric spherical deconvolution approach and represented using a dictionary created with the exponential decay components along different possible directions. Volume fractions of fibers along these orientations define the dictionary weights. The data at low resolution is modeled using a spatial partial volume representation. The proposed dictionary representation and sparsity priors consider the dependence between fiber orientations and the spatial redundancy in data representation. Our method exploits the sparsity of fiber orientations, therefore facilitating inference from under-sampled data. Experimental results show improved accuracy and decreased uncertainty in fiber orientation estimates. For under-sampled data, the proposed method is also shown to produce more robust estimates of fiber orientations.

3D Fiber Orientation Simulation for Plastic Injection Molding

NASA Astrophysics Data System (ADS)

Lin, Baojiu; Jin, Xiaoshi; Zheng, Rong; Costa, Franco S.; Fan, Zhiliang

2004-06-01

Glass fiber reinforced polymer is widely used in the products made using injection molding processing. The distribution of fiber orientation inside plastic parts has direct effects on quality of molded parts. Using computer simulation to predict fiber orientation distribution is one of most efficient ways to assist engineers to do warpage analysis and to find a good design solution to produce high quality plastic parts. Fiber orientation simulation software based on 2-1/2D (midplane /Dual domain mesh) techniques has been used in industry for a decade. However, the 2-1/2D technique is based on the planar Hele-Shaw approximation and it is not suitable when the geometry has complex three-dimensional features which cannot be well approximated by 2D shells. Recently, a full 3D simulation software for fiber orientation has been developed and integrated into Moldflow Plastics Insight 3D simulation software. The theory for this new 3D fiber orientation calculation module is described in this paper. Several examples are also presented to show the benefit in using 3D fiber orientation simulation.

On the measurement of fiber orientation in fiberboard

Treesearch

Otto Suchsland; Charles W. McMillin

1983-01-01

An attempt to measure the vertical component of fiber orientation in fiberboard is described. The experiment is based on the obvious reduction of the furnish fiber length which occurs by cutting thin microtome sections of the board parallel to the board plane. Only when no vertical fiber orientation component is present will the fibers contained in these sections have...

Visualizing Collagen Network Within Human and Rhesus Monkey Vocal Folds Using Polarized Light Microscopy

PubMed Central

Julias, Margaret; Riede, Tobias; Cook, Douglas

2014-01-01

Objectives Collagen fiber content and orientation affect the viscoelastic properties of the vocal folds, determining oscillation characteristics during speech and other vocalization. The investigation and reconstruction of the collagen network in vocal folds remains a challenge, because the collagen network requires at least micron-scale resolution. In this study, we used polarized light microscopy to investigate the distribution and alignment of collagen fibers within the vocal folds. Methods Data were collected in sections of human and rhesus monkey (Macaca mulatta) vocal folds cut at 3 different angles and stained with picrosirius red. Results Statistically significant differences were found between different section angles, implying that more than one section angle is required to capture the network’s complexity. In the human vocal folds, the collagen fiber distribution continuously varied across the lamina propria (medial to lateral). Distinct differences in birefringence distribution were observed between the species. For the human vocal folds, high birefringence was observed near the thyroarytenoid muscle and near the epithelium. However, in the rhesus monkey vocal folds, high birefringence was observed near the epithelium, and lower birefringence was seen near the thyroarytenoid muscle. Conclusions The differences between the collagen networks in human and rhesus monkey vocal folds provide a morphological basis for differences in viscoelastic properties between species. PMID:23534129

Effect of fiber orientation on the failure behavior of a glass-fiber reinforced thermoplastic composite

NASA Astrophysics Data System (ADS)

Liang, Jiaai; Kalyanasundaram, Shankar

2017-05-01

In this study, hour-glass specimens made of a glass-fiber reinforced polypropylene composite with different fiber orientations were stamp formed in an open die. Strains on the surfaces of these specimens were recorded by a 3D photogrammetric measurement system. Specimens were cut into the designed shapes with two different fiber orientations [0°/90° and 45°/45°]. Based on the forming limit diagrams drawn for these material systems, it is found that change in fiber orientation induces change in deformation mode and different forming limit in strains.

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep

Here, we present a detailed methodology for experimental measurement of fiber orientation distribution in injection-molded discontinuous fiber composites using the method of ellipses on two-dimensional cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. We developed a marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori–Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the fiber orientation distribution measurements.« less

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE PAGES

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep; ...

2017-09-28

Here, we present a detailed methodology for experimental measurement of fiber orientation distribution in injection-molded discontinuous fiber composites using the method of ellipses on two-dimensional cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. We developed a marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori–Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the fiber orientation distribution measurements.« less

Embedded sensor having an identifiable orientation

DOEpatents

Bennett, Thomas E.; Nelson, Drew V.

2002-01-01

An apparatus and method is described wherein a sensor, such as a mechanical strain sensor, embedded in a fiber core, is "flagged" to identify a preferred orientation of the sensor. The identifying "flag" is a composite material, comprising a plurality of non-woven filaments distributed in a resin matrix, forming a small planar tab. The fiber is first subjected to a stimulus to identify the orientation providing the desired signal response, and then sandwiched between first and second layers of the composite material. The fiber, and therefore, the sensor orientation is thereby captured and fixed in place. The process for achieving the oriented fiber includes, after identifying the fiber orientation, carefully laying the oriented fiber onto the first layer of composite, moderately heating the assembled layer for a short period in order to bring the composite resin to a "tacky" state, heating the second composite layer as the first, and assembling the two layers together such that they merge to form a single consolidated block. The consolidated block achieving a roughly uniform distribution of composite filaments near the embedded fiber such that excess resin is prevented from "pooling" around the periphery of the fiber.

Relationship between Fiber Furnish and the Structural Performance of MDF

Treesearch

Leslie H. Groom; Laurence Mott; Stephen Shaler

1999-01-01

The structural performance of medium density fiberboard (MDF) is attributable to three primary variables which are: physical and mechanical properties of individual wood fibers; fiber-to-fiber stress transfer; and fiber orientation. These origins of fiber properties and stress transfer can be traced to the fiber generation method wherein fiber orientation is associated...

Obtaining short-fiber orientation model parameters using non-lubricated squeeze flow

NASA Astrophysics Data System (ADS)

Lambert, Gregory; Wapperom, Peter; Baird, Donald

2017-12-01

Accurate models of fiber orientation dynamics during the processing of polymer-fiber composites are needed for the design work behind important automobile parts. All of the existing models utilize empirical parameters, but a standard method for obtaining them independent of processing does not exist. This study considers non-lubricated squeeze flow through a rectangular channel as a solution. A two-dimensional finite element method simulation of the kinematics and fiber orientation evolution along the centerline of a sample is developed as a first step toward a fully three-dimensional simulation. The model is used to fit to orientation data in a short-fiber-reinforced polymer composite after squeezing. Fiber orientation model parameters obtained in this study do not agree well with those obtained for the same material during startup of simple shear. This is attributed to the vastly different rates at which fibers orient during shearing and extensional flows. A stress model is also used to try to fit to experimental closure force data. Although the model can be tuned to the correct magnitude of the closure force, it does not fully recreate the transient behavior, which is attributed to the lack of any consideration for fiber-fiber interactions.

Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

NASA Astrophysics Data System (ADS)

Nguyen Thi, T. B.; Yokoyama, A.; Ota, K.; Kodama, K.; Yamashita, K.; Isogai, Y.; Furuichi, K.; Nonomura, C.

2014-05-01

One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, which is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.

Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating.

PubMed

Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

2016-09-11

An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the "cladding" FBG along the fiber cross-section.

Impacts of fiber orientation and milling on observed crystallinity in jack pine

Treesearch

Umesh P. Agarwal; Sally A. Ralph; Richard S. Reiner; Roderquita K. Moore; Carlos Baez

2014-01-01

Influences of fiber orientation and milling on wood cellulose crystallinity were studied using jack pine wood. The fiber orientation effects were measured by sampling rectangular wood blocks in radial, tangential, and cross-sectional orientations. The influence of milling was studied by analyzing the unsieved and sieved milled wood fractions (all

Upscaling the diffusion equations in particulate media made of highly conductive particles. II. Application to fibrous materials.

PubMed

Vassal, J-P; Orgéas, L; Favier, D; Auriault, J-L; Le Corre, S

2008-01-01

In paper I [Vassal, Phys. Rev. E77, 011302 (2008)] of this contribution, the effective diffusion properties of particulate media with highly conductive particles and particle-particle interfacial barriers have been investigated with the homogenization method with multiple scale asymptotic expansions. Three different macroscopic models have been proposed depending on the quality of contacts between particles. However, depending on the nature and the geometry of particles contained in representative elementary volumes of the considered media, localization problems to be solved to compute the effective conductivity of the two first models can rapidly become cumbersome, time and memory consuming. In this second paper, the above problem is simplified and applied to networks made of slender, wavy and entangled fibers. For these types of media, discrete formulations of localization problems for all macroscopic models can be obtained leading to very efficient numerical calculations. Semianalytical expressions of the effective conductivity tensors are also proposed under simplifying assumptions. The case of straight monodisperse and homogeneously distributed slender fibers with a circular cross section is further explored. Compact semianalytical and analytical estimations are obtained when fiber-fiber contacts are perfect or very poor. Moreover, two discrete element codes have been developed and used to solve localization problems on representative elementary volumes for the same types of contacts. Numerical results underline the significant roles of the fiber content, the orientation of fibers as well as the relative position and orientation of contacting fibers on the effective conductivity tensors. Semianalytical and analytical predictions are discussed and compared with numerical results.

Numerical approach of the injection molding process of fiber-reinforced composite with considering fiber orientation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen Thi, T. B., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp; Yokoyama, A., E-mail: thanhbinh.skku@gmail.com, E-mail: yokoyama@kit.ac.jp; Ota, K., E-mail: kei-ota@toyobo.jp, E-mail: katsuhiro-kodama@toyobo.jp, E-mail: katsuhisa-yamashita@toyobo.jp, E-mail: yumiko-isogai@toyobo.jp, E-mail: kenji-furuichi@toyobo.jp, E-mail: chisato-nonomura@toyobo.jp

2014-05-15

One of the most important challenges in the injection molding process of the short-glass fiber/thermoplastic composite parts is being able to predict the fiber orientation, since it controls the mechanical and the physical properties of the final parts. Folgar and Tucker included into the Jeffery equation a diffusive type of term, which introduces a phenomenological coefficient for modeling the randomizing effect of the mechanical interactions between the fibers, to predict the fiber orientation in concentrated suspensions. Their experiments indicated that this coefficient depends on the fiber volume fraction and aspect ratio. However, a definition of the fiber interaction coefficient, whichmore » is very necessary in the fiber orientation simulations, hasn't still been proven yet. Consequently, this study proposed a developed fiber interaction model that has been introduced a fiber dynamics simulation in order to obtain a global fiber interaction coefficient. This supposed that the coefficient is a sum function of the fiber concentration, aspect ratio, and angular velocity. The proposed model was incorporated into a computer aided engineering simulation package C-Mold. Short-glass fiber/polyamide-6 composites were produced in the injection molding with the fiber weight concentration of 30 wt.%, 50 wt.%, and 70 wt.%. The physical properties of these composites were examined, and their fiber orientation distributions were measured by micro-computed-tomography equipment μ-CT. The simulation results showed a good agreement with experiment results.« less

Effect of fiber diameter and orientation on fibroblast morphology and proliferation on electrospun poly(D,L-lactic-co-glycolic acid) meshes.

PubMed

Bashur, Chris A; Dahlgren, Linda A; Goldstein, Aaron S

2006-11-01

Engineered ligament tissues are promising materials for the repair of tears and ruptures, but require the development of biomaterial scaffolds that not only support physiologically relevant loads, but also possess architectures capable of orienting cell adhesion and extracellular matrix deposition. Based on evidence that micron-scale topographic features induce cell orientation through a contact guidance phenomenon, we postulate that oriented micron-scale fiber meshes-formed by the electrospinning process-can regulate cell morphology. To test this, fused fiber meshes of poly(d,l-lactic-co-glycolic acid) (PLGA) were electrospun onto rigid supports under conditions that produced mean fiber diameters of 0.14-3.6 microm, and angular standard deviations of 31-60 degrees . Analysis of the morphology of adherent NIH 3T3 fibroblasts indicated that projected cell area and aspect ratio increased systematically with both increasing fiber diameter and degree of fiber orientation. Importantly, cell morphology on 3.6 microm fibers was similar to that on spincoated PLGA films. Finally, cell densities on electrospun meshes were not significantly different from spincoated PLGA, indicating that cell proliferation is not sensitive to fiber diameter or orientation.

Orientation-Dependent Displacement Sensor Using an Inner Cladding Fiber Bragg Grating

PubMed Central

Yang, Tingting; Qiao, Xueguang; Rong, Qiangzhou; Bao, Weijia

2016-01-01

An orientation-dependent displacement sensor based on grating inscription over a fiber core and inner cladding has been demonstrated. The device comprises a short piece of multi-cladding fiber sandwiched between two standard single-mode fibers (SMFs). The grating structure is fabricated by a femtosecond laser side-illumination technique. Two well-defined resonances are achieved by the downstream both core and cladding fiber Bragg gratings (FBGs). The cladding resonance presents fiber bending dependence, together with a strong orientation dependence because of asymmetrical distribution of the “cladding” FBG along the fiber cross-section. PMID:27626427

The Effects of Fiber Orientation and Volume Fraction of Fiber on Mechanical Properties of Additively Manufactured Composite Material

NASA Astrophysics Data System (ADS)

Kuchipudi, Suresh Chandra

Additive manufacturing (AM) also known as 3D printing has tremendous advancements in recent days with a vast number of applications in industrial, automotive, architecture, consumer projects, fashion, toys, food, art, etc. Composite materials are widely used in structures with weight as a critical factor especially in aerospace industry. Recently, additive manufacturing technology, a rapidly growing innovative technology, has gained lot of importance in making composite materials. The properties of composite materials depend upon the properties of constituent's matrix and fiber. There is lot of research on effect of fiber orientation on mechanical properties of composite materials made using conventional manufacturing methods. It will be interesting and relevant to study the relationship between the fiber orientation and fiber volume with mechanical properties of additively manufactured composite materials. This thesis work presents experimental investigation of mechanical behavior like tensile strength and fatigue life with variation in fiber orientation and fiber volume fraction of 3D printed composite materials. The aim is to study the best combination of volume fraction of fiber and fiber orientation that has better fatigue strength for additive manufactured composite materials. Using this study, we can decide the type of orientation and volume percent for desired properties. This study also finds the range of fatigue limits of 3d printed composite materials.

Orientation of Steel Fibers in Magnetically Driven Concrete and Mortar.

PubMed

Xue, Wen; Chen, Ju; Xie, Fang; Feng, Bing

2018-01-22

The orientation of steel fibers in magnetically driven concrete and magnetically driven mortar was experimentally studied in this paper using a magnetic method. In the magnetically driven concrete, a steel slag was used to replace the coarse aggregate. In the magnetically driven mortar, steel slag and iron sand were used to replace the fine aggregate. A device was established to provide the magnetic force. The magnetic force was used to rotate the steel fibers. In addition, the magnetic force was also used to vibrate the concrete and mortar. The effect of magnetic force on the orientation of steel fibers was examined by comparing the direction of fibers before and after vibration. The effect of magnetically driven concrete and mortar on the orientation of steel fibers was also examined by comparing specimens to normal concrete and mortar. It is shown that the fibers could rotate about 90° in magnetically driven concrete. It is also shown that the number of fibers rotated in magnetically driven mortar was much more than in mortar vibrated using a shaking table. A splitting test was performed on concrete specimens to investigate the effect of fiber orientation. In addition, a flexural test was also performed on mortar test specimens. It is shown that the orientation of the steel fibers in magnetically driven concrete and mortar affects the strength of the concrete and mortar specimens.

Orientation of Steel Fibers in Magnetically Driven Concrete and Mortar

PubMed Central

Xue, Wen; Chen, Ju; Xie, Fang; Feng, Bing

2018-01-01

The orientation of steel fibers in magnetically driven concrete and magnetically driven mortar was experimentally studied in this paper using a magnetic method. In the magnetically driven concrete, a steel slag was used to replace the coarse aggregate. In the magnetically driven mortar, steel slag and iron sand were used to replace the fine aggregate. A device was established to provide the magnetic force. The magnetic force was used to rotate the steel fibers. In addition, the magnetic force was also used to vibrate the concrete and mortar. The effect of magnetic force on the orientation of steel fibers was examined by comparing the direction of fibers before and after vibration. The effect of magnetically driven concrete and mortar on the orientation of steel fibers was also examined by comparing specimens to normal concrete and mortar. It is shown that the fibers could rotate about 90° in magnetically driven concrete. It is also shown that the number of fibers rotated in magnetically driven mortar was much more than in mortar vibrated using a shaking table. A splitting test was performed on concrete specimens to investigate the effect of fiber orientation. In addition, a flexural test was also performed on mortar test specimens. It is shown that the orientation of the steel fibers in magnetically driven concrete and mortar affects the strength of the concrete and mortar specimens. PMID:29361798

Effects of Fiber Orientation on the Frictional Properties and Damage of Regenerative Articular Cartilage Surfaces

PubMed Central

Accardi, Mario Alberto; McCullen, Seth D.; Callanan, Anthony; Chung, Sangwon; Cann, Philippa M.

2013-01-01

Articular cartilage provides a low-friction, wear-resistant surface for diarthrodial joints. Due to overloading and overuse, articular cartilage is known to undergo significant wear and degeneration potentially resulting in osteoarthritis (OA). Regenerative medicine strategies offer a promising solution for the treatment of articular cartilage defects and potentially localized early OA. Such strategies rely on the development of materials to restore some aspects of cartilage. In this study, microfibrous poly(ɛ-caprolactone) scaffolds of varying fiber orientations (random and aligned) were cultured with bovine chondrocytes for 4 weeks in vitro, and the mechanical and frictional properties were evaluated. Mechanical properties were quantified using unconfined compression and tensile testing techniques. Frictional properties were investigated at physiological compressive strains occurring in native articular cartilage. Scaffolds were sheared along the fiber direction, perpendicular to the fiber direction and in random orientation. The evolution of damage as a result of shear was evaluated via white light interferometry and scanning electron microscopy. As expected, the fiber orientation strongly affected the tensile properties as well as the compressive modulus of the scaffolds. Fiber orientation did not significantly affect the equilibrium frictional coefficient, but it was, however, a key factor in dictating the evolution of surface damage on the surface. Scaffolds shear tested perpendicular to the fiber orientation displayed the highest surface damage. Our results suggest that the fiber orientation of the scaffold implanted in the joint could strongly affect its resistance to damage due to shear. Scaffold fiber orientation should thus be carefully considered when using microfibrous scaffolds. PMID:23688110

Multiscale Shannon's Entropy Modeling of Orientation and Distance in Steel Fiber Micro-Tomography Data.

PubMed

Chiverton, John P; Ige, Olubisi; Barnett, Stephanie J; Parry, Tony

2017-11-01

This paper is concerned with the modeling and analysis of the orientation and distance between steel fibers in X-ray micro-tomography data. The advantage of combining both orientation and separation in a model is that it helps provide a detailed understanding of how the steel fibers are arranged, which is easy to compare. The developed models are designed to summarize the randomness of the orientation distribution of the steel fibers both locally and across an entire volume based on multiscale entropy. Theoretical modeling, simulation, and application to real imaging data are shown here. The theoretical modeling of multiscale entropy for orientation includes a proof showing the final form of the multiscale taken over a linear range of scales. A series of image processing operations are also included to overcome interslice connectivity issues to help derive the statistical descriptions of the orientation distributions of the steel fibers. The results demonstrate that multiscale entropy provides unique insights into both simulated and real imaging data of steel fiber reinforced concrete.

Rotational 3D printing of damage-tolerant composites with programmable mechanics.

PubMed

Raney, Jordan R; Compton, Brett G; Mueller, Jochen; Ober, Thomas J; Shea, Kristina; Lewis, Jennifer A

2018-02-06

Natural composites exhibit exceptional mechanical performance that often arises from complex fiber arrangements within continuous matrices. Inspired by these natural systems, we developed a rotational 3D printing method that enables spatially controlled orientation of short fibers in polymer matrices solely by varying the nozzle rotation speed relative to the printing speed. Using this method, we fabricated carbon fiber-epoxy composites composed of volume elements (voxels) with programmably defined fiber arrangements, including adjacent regions with orthogonally and helically oriented fibers that lead to nonuniform strain and failure as well as those with purely helical fiber orientations akin to natural composites that exhibit enhanced damage tolerance. Our approach broadens the design, microstructural complexity, and performance space for fiber-reinforced composites through site-specific optimization of their fiber orientation, strain, failure, and damage tolerance. Copyright © 2018 the Author(s). Published by PNAS.

Research on Extrusion of Rubber Composites Reinforced by Short Fibers Orientation Based on FEA

NASA Astrophysics Data System (ADS)

Zhang, Dewei; Wang, Chuansheng; Shen, Bo; Li, Shaoming; Bian, Huiguang

2018-06-01

In recent years, rubber composites reinforced by short fibers has been researched deeply, because of its good performances such as higher wear resistance, higher cut resistance and so on. Some research results indicated that if short fibers get orientation in rubber composites, the performances of rubber products could be promoted greatly. But how to make short fibers get orientation in rubber matrix during extrusion is still a real problem. And there are many parameters affect the short fibers orientation. So, in this paper, the effects of die structure including expansion-die and dam-expansion-die on extrusion flow field of short fiber and rubber composite material during extrusion process has been researched by Polyflow. And the FEA results about the pressure field, velocity field and the velocity vector of the rubber composites flow field indicate that, comparing with expansion-die and the dam-expansion-die, the latter one is better for the extrusion process of rubber composites and making short fibers get radial orientation in rubber matrix.

Fiber estimation and tractography in diffusion MRI: Development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values

PubMed Central

Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

2015-01-01

Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, and consequently tractography and the ability to recover complex white-matter pathways, as well as differences between results due to choice of analysis method and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment “ball and stick” model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm2) common to clinical studies. We found the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of fibers. Fiber detection rate was found to be the most distinguishing characteristic between the methods, and a significant factor for complete recovery of tractography through complex white-matter pathways. For example, while all methods recovered similar tractography of prominent white matter pathways of limited fiber crossing, CSD (which had the highest fiber detection rate, especially for voxels containing three fibers) recovered the greatest number of fibers and largest fraction of correct tractography for a complex three-fiber crossing region. The synthetic data sets, ground-truth, and tools for quantitative evaluation are publically available on the NITRC website as the project “Simulated DW-MRI Brain Data Sets for Quantitative Evaluation of Estimated Fiber Orientations” at http://www.nitrc.org/projects/sim_dwi_brain PMID:25555998

Rotational 3D printing of damage-tolerant composites with programmable mechanics

PubMed Central

Raney, Jordan R.; Compton, Brett G.; Ober, Thomas J.; Shea, Kristina; Lewis, Jennifer A.

2018-01-01

Natural composites exhibit exceptional mechanical performance that often arises from complex fiber arrangements within continuous matrices. Inspired by these natural systems, we developed a rotational 3D printing method that enables spatially controlled orientation of short fibers in polymer matrices solely by varying the nozzle rotation speed relative to the printing speed. Using this method, we fabricated carbon fiber–epoxy composites composed of volume elements (voxels) with programmably defined fiber arrangements, including adjacent regions with orthogonally and helically oriented fibers that lead to nonuniform strain and failure as well as those with purely helical fiber orientations akin to natural composites that exhibit enhanced damage tolerance. Our approach broadens the design, microstructural complexity, and performance space for fiber-reinforced composites through site-specific optimization of their fiber orientation, strain, failure, and damage tolerance. PMID:29348206

Mechanical model of suture joints with fibrous connective layer

NASA Astrophysics Data System (ADS)

Miroshnichenko, Kateryna; Liu, Lei; Tsukrov, Igor; Li, Yaning

2018-02-01

A composite model for suture joints with a connective layer of aligned fibers embedded in soft matrix is proposed. Based on the principle of complementary virtual work, composite cylinder assemblage (CCA) approach and generalized self-consistent micro-mechanical models, a hierarchical homogenization methodology is developed to systematically quantify the synergistic effects of suture morphology and fiber orientation on the overall mechanical properties of sutures. Suture joints with regular triangular wave-form serve as an example material system to apply this methodology. Both theoretical and finite element mechanical models are developed and compared to evaluate the overall normal stiffness of sutures as a function of wavy morphology of sutures, fiber orientation, fiber volume fraction, and the mechanical properties of fibers and matrix in the interfacial layer. It is found that generally due to the anisotropy-induced coupling effects between tensile and shear deformation, the effective normal stiffness of sutures is highly dependent on the fiber orientation in the connective layer. Also, the effective shear modulus of the connective layer and the stiffness ratio between the fiber and matrix significantly influence the effects of fiber orientation. In addition, optimal fiber orientations are found to maximize the stiffness of suture joints.

Longitudinal analysis on human cervical tissue using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gan, Yu; Yao, Wang; Myers, Kristin M.; Vink, Joy-Sarah Y.; Wapner, Ronald J.; Hendon, Christine P.

2017-02-01

Uterine cervical collagen fiber network is vital to the normal cervical function in pregnancy. Previously, we presented an orientation estimation method to enable dispersion analysis on a single axial slice of human cervical tissue obtained from the upper half of cervix using optical coherence tomography (OCT). How the collagen fiber network structure changes from the internal os (top of the cervix which meets the uterus) to external os (bottom of cervix which extends into the vagina), remains unknown due to depth penetration limitations of OCT. To establish a collagen fiber directionality "map" of the entire cervix, we imaged serial axial slices of human NP (n=11) and PG (n=2) cervical tissue obtained from the internal to external os using Institutional Review Board approved protocols at Columbia University Medical Center. Each slice was divided into four quadrants. In each quadrant, we stitched multiple overlapped OCT volumes and analyzed the en face images that were parallel to the surface. A pixel-wise directionality map was generated. We analyzed fiber trend by measuring the mean angles and quantified dispersion by calculating the standard deviation of the fiber direction over a region of 400 μm × 400 μm. For the initial four samples, our analysis confirms a circumferential fiber pattern in the outer region of slices at all depths. We found that the standard deviation close to internal os showed no significance to the standard deviation close to external os (p>0.05), indicating comparable dispersion.

A Model for Fiber Length Attrition in Injection-Molded Long-Fiber Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

TuckerIII, Charles L.; Phelps, Jay H; El-Rahman, Ahmed Abd

2013-01-01

Long-fiber thermoplastic (LFT) composites consist of an engineering thermoplastic matrix with glass or carbon reinforcing fibers that are initially 10 to 13 mm long. When an LFT is injection molded, flow during mold filling orients the fibers and degrades the fiber length. Fiber orientation models for injection molding are well developed, and special orientation models for LFTs have been developed. Here we present a detailed quantitative model for fiber length attrition in a flowing fiber suspension. The model tracks a discrete fiber length distribution (FLD) at each spatial node. Key equations are a conservation equation for total fiber length, andmore » a breakage rate equation. The breakage rate is based on buckling of fibers due to hydrodynamic forces, when the fibers are in unfavorable orientations. The FLD model is combined with a mold filling simulation to predict spatial and temporal variations in fiber length distribution in a mold cavity during filling. The predictions compare well to experiments on a glassfiber/ PP LFT molding. Fiber length distributions predicted by the model are easily incorporated into micromechanics models to predict the stress-strain behavior of molded LFT materials. Author to whom correspondence should be addressed; electronic mail: ctucker@illinois.edu 1« less

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation.

PubMed

Choi, Jeong-Il; Lee, Bang Yeon

2015-09-30

The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber's suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

Modeling and Predicting the Stress Relaxation of Composites with Short and Randomly Oriented Fibers

PubMed Central

Obaid, Numaira; Sain, Mohini

2017-01-01

The addition of short fibers has been experimentally observed to slow the stress relaxation of viscoelastic polymers, producing a change in the relaxation time constant. Our recent study attributed this effect of fibers on stress relaxation behavior to the interfacial shear stress transfer at the fiber-matrix interface. This model explained the effect of fiber addition on stress relaxation without the need to postulate structural changes at the interface. In our previous study, we developed an analytical model for the effect of fully aligned short fibers, and the model predictions were successfully compared to finite element simulations. However, in most industrial applications of short-fiber composites, fibers are not aligned, and hence it is necessary to examine the time dependence of viscoelastic polymers containing randomly oriented short fibers. In this study, we propose an analytical model to predict the stress relaxation behavior of short-fiber composites where the fibers are randomly oriented. The model predictions were compared to results obtained from Monte Carlo finite element simulations, and good agreement between the two was observed. The analytical model provides an excellent tool to accurately predict the stress relaxation behavior of randomly oriented short-fiber composites. PMID:29053601

Creep of experimental short fiber-reinforced composite resin.

PubMed

Garoushi, Sufyan; Kaleem, Muhammad; Shinya, Akikazu; Vallittu, Pekka K; Satterthwaite, Julian D; Watts, David C; Lassila, Lippo V J

2012-01-01

The purpose of this study was to investigate the reinforcing effect of short E-glass fiber fillers oriented in different directions on composite resin under static and dynamic loading. Experimental short fiber-reinforced composite resin (FC) was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of resin, and 55 wt% of silane-treated silica fillers. Three groups of specimens (n=5) were tested: FC with isotropic fiber orientation, FC with anisotropic fiber orientation, and particulate-filled composite resin (PFC) as a control. Time-dependent creep and recovery were recorded. ANOVA revealed that after secondary curing in a vacuum oven and after storage in dry condition for 30 days, FC with isotropic fiber orientation (1.73%) exhibited significantly lower static creep value (p<0.05) than PFC (2.54%). For the different curing methods and storage conditions evaluated in this study, FC achieved acceptable static and dynamic creep values when compared to PFC.

Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation

PubMed Central

Choi, Jeong-Il; Lee, Bang Yeon

2015-01-01

The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber’s suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking. PMID:28793595

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - Second FY 2015 Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Kijewski, Seth A.

During the second quarter of FY 2015, the following technical progress has been made toward project milestones: 1) Autodesk reviewed 3D fiber orientation distribution (FOD) comparisons and provided support on improving accuracy. 2) Autodesk reviewed fiber length distribution (FLD) data comparisons and provided suggestions, assisted PNNL in FOD and FLD parameter settings optimization, and advised PNNL on appropriate through thickness thermal conductivity for improved frozen layer effect on FOD predictions. Autodesk also participated in project review meetings including preparations and discussions towards passing the go/no-go decision point. 3) Autodesk implemented an improved FOD inlet profile specification method through the partmore » thickness for 3D meshes and provided an updated ASMI research version to PNNL. 4) The University of Illinois (Prof. C.L. Tucker) provided Autodesk with ideas to improve fiber orientation modeling 5) Purdue University re-measured fiber orientation for the fast-fill 50wt% LCF/PA66 edge-gated plaque, and delivered the fiber orientation data for this plaque at the selected locations (named A, B, and C, Figure 1) to PNNL. Purdue also re-measured fiber orientation for locations A on the fast-fill 30wt% LCF/PP and 50wt% LCF/PA66 center-gated plaques, which exhibited anomalous fiber orientation behavior. 6) Purdue University conducted fiber length measurements and delivered the length data to PNNL for the purge materials (slow-fill 30wt% LCF/PP and 30wt% LCF/PA66 purge materials) and PlastiComp plaques selected on the go/no-go list for fiber length model validation (i.e., slow-fill edge-gated 30wt% LCF/PP and 30wt% LCF/PA66 plaques, Locations A, B, and C). 7) PNNL developed a method to recover intact carbon fibers from LCF/PA66 materials. Isolated fibers were shipped to Purdue for length distribution analysis. 8) PNNL completed ASMI mid-plane analyses for all the PlastiComp plaques defined on the go/no-go list for fiber orientation (FO) model validation and compared the predicted fiber orientations with the measured data provided by Purdue at Locations A, B, and C on these plaques. The 15% accuracy criterion based on evaluation of tensile and bending stiffness was used to assess the accuracy in fiber orientation predictions. 9) PNNL completed ASMI mid-plane analyses for all the PlastiComp plaques defined on the go/no-go list for fiber length distribution (FLD) model validation and compared the predicted length distributions with the measured data provided by Purdue at Locations A, B, and C on these plaques. The 15% accuracy criterion based on evaluation of tensile and bending stiffness was used to assess the accuracy in fiber orientation predictions. 10) PNNL tested the new ASMI version received from Autodesk in March 2015, examined and discussed 3D fiber orientation predictions for PlastiComp plaques. 11) PlastiComp, Inc. (PlastiComp), Toyota Research Institute North America (Toyota) and Magna Exteriors and Interiors Corporation (Magna) participated in discussions with team members on the go/no-go plan. Toyota continued the discussion with Magna on tool modification for molding the complex part in order to achieve the target fiber length in the part.« less

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2015 First Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Kijewski, Seth A.

2015-01-29

During the first quarter of FY 2015, the following technical progress has been made toward project milestones: 1) Autodesk delivered a new research version of ASMI to PNNL. This version includes the improved 3D fiber orientation solver, and the reduced order model (ROM) for fiber length distribution using the proper orthogonal decomposition (POD) implemented in the mid-plane, dual-domain and 3D solvers. 2) Autodesk coordinated a conference paper with PNNL reporting ASMI mid-plane fiber orientation predictions compared with the measured data for two PlastiComp plaques. This paper was accepted for presentation at the 2015 Society for Plastics Engineers (SPE) ANTEC conference.more » 3) The University of Illinois (Prof. Tucker) assisted team members from Purdue with fiber orientation measurement techniques, including interpretation of off-axis cross sections. 4) The University of Illinois assisted Autodesk team members with software implementation of the POD approach for fiber length modeling, and with fiber orientation modeling. 5) The University of Illinois co-authored in the SPE ANTEC paper, participated with the team in discussions of plaque data and model results, and participated in the definition of go/no-go experiments and data. 6) Purdue University (Purdue) conducted fiber orientation measurements for 3 PlastiComp plaques: fast-fill 30wt% LCF/PP center-gated, fast-fill 50wt% LCF/PA66 edge-gated and fast-fill 50wt% LCF/PA66 center-gated plaques, and delivered the fiber orientation data for these plaques at the selected locations (named A, B, and C) to PNNL. However, the data for the fast-fill 50wt% LCF/PA66 edge-gated plaque exhibited unusual variations and could not be used for the model validation. Purdue will re-measure fiber orientation for this plaque. 7) Based on discussions with the University of Illinois Purdue explained the ambiguity in the measurements of the fiber orientation components. 8) PNNL discussed with team members to establish a go/no-go decision plan for the project and submitted the established plan to DOE. 9) PNNL performed ASMI mid-plane analyses for the fast-fill center-gated 30wt% LCF/PP and 50wt% LCF/PA66 plaques and compared the predicted fiber orientations with the measured data provided by Purdue at Locations A, B, and C on these plaques. 10) Based on discussions with the University of Illinois and Autodesk, PNNL proposed a procedure to adjust fiber orientation data for Location A of the center-gated plaques so that the data can be expressed and interpreted in the flow/cross-flow direction coordinate system. 11) PNNL tested the new ASMI version received from Autodesk, examined and discussed 3D fiber orientation predictions for PlastiComp plaques. 12) PlastiComp, Inc. (PlastiComp), Toyota Research Institute North America (Toyota) and Magna Exteriors and Interiors Corp. (Magna) participated in discussions with team members on the go/no-go plan and the issues related to fiber length measurements. Toyota continued the discussion with Magna on tool modification for molding the complex part in order to achieve the target fiber length in the part.« less

Improving Paper Machine Efficiency/Productivity through On-line Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cyrus K Aidun

2007-08-31

This project involves implementing a new technology, microforming, in a headbox to produce an isotropic sheet with significant reductions in the MD/CD stiffness ratio (increasing CD specific STFI) and improved sheet uniformity. Microforming involves generating axial vorticity (i.e., swirl) prior to the converging nozzle of the headbox by retrofitting an existing tube block with swirl generation devices referred to as Vortigen system. The Vortigen system developed in this project is a retrofit technology to a hydraulic headbox tube block. The tubes in the tube block are re-designed to generate axial vorticity (or swirl) in the tubes. This type of flowmore » results in higher intensity small-scale turbulence in the forming jet at the slice. The net effect, as demonstrated in pilot and commercial trials, is improvement in formation and surface smoothness, lower MD/CD tensile ratio, and consequently, higher CD strength properties such as CD STFI, Ring Crush and tensile or breaking length. The objective of this project is to implement microforming by developing the retrofit technology for generation and on-line control of axial vorticity in the tubes to optimize turbulent scale and intensity, and consequently, fiber network structure properties in the sheet. This technology results in significant improvements in the performance and capital effectiveness of the paper machine (PM) for a fraction of the cost to replace a headbox. In this project we have developed and demonstrated the concept of generating axial vorticity to control the fiber orientation in the converging zone of the headbox, and to produce a sheet with isotropic fiber orientation. The technology developed here has been demonstrated in static form on several pilot trials and two series of commercial trials. The economic feasibility of this technology is based primarily on fiber savings in cases where a more isotropic fiber orientation can be used to reduce the basis weight of the product. Even a 5% decrease in basis weight will results in substantial savings covering the cost of a commercial retrofit in 6 months or less in a medium size machine. The project also resulted in significant amount of information on fiber orientation in turbulent flow and in a converging nozzle where the results can be used in other applications, such as formation of composite materials. Several MS and Ph.D. students and postdoctoral associates have been trained as part of this project.« less

Uncertainty quantification of fiber orientation distribution measurements for long-fiber-reinforced thermoplastic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bhisham N.; Naragani, Diwakar; Nguyen, Ba Nghiep

We present a detailed methodology for experimental measurement of fiber orientation distribution (FOD) in injection-molded discontinuous fiber composites using the method of ellipses on 2D cross sections. Best practices to avoid biases occurring during surface preparation and optical imaging of carbon-fiber-reinforced thermoplastics are discussed. A marker-based watershed transform routine for efficient image segmentation and the separation of touching fiber ellipses is developed. The sensitivity of the averaged orientation tensor to the image sample size is studied for the case of long-fiber thermoplastics. A Mori-Tanaka implementation of the Eshelby model is then employed to quantify the sensitivity of elastic stiffness predictionsmore » to biases in the FOD measurements.« less

Processing-microstructure models for short- and long-fiber thermoplastic composites

NASA Astrophysics Data System (ADS)

Phelps, Jay H.

The research for this thesis has explored the important microstructural variables for injection-molded thermoplastic composites with discontinuous fiber reinforcement. Two variables, the distributions of fiber orientation and fiber length after processing, have proven to be not only important for correct material property prediction but also difficult to predict using currently available modeling and simulation techniques. In this work, we develop new models for the prediction of these two microstructural variables. Previously, the Folgar-Tucker model has been widely used to predict fiber orientation in injection molded SFT composites. This model accounts for the effects of both hydrodynamics and fiber-fiber interactions in order to give a prediction for a tensorial measure of fiber orientation. However, when applied to at least some classes of LFTs, this model does not match all components of experimental fiber orientation tensor data. In order to address this shortcoming of the model, we hypothesize that Folgar and Tucker's phenomenological treatment of the effects of fiber-fiber interactions with an isotropic rotary diffusion contribution to the rate of change of orientation is insufficient for materials with longer fibers. Instead, this work develops a fiber orientation model that incorporates anisotropic rotary diffusion (ARD). From kinetic theory we derive a general family of evolution equations for the second-order orientation tensor, correcting errors in earlier treatments, and identify a specific equation that is useful for predicting orientation in LFTs. The amount of diffusivity in this model used to approximate the effect of fiber-fiber interactions in each direction is assumed to depend on a second-order space tensor, which is taken to be a function of the orientation state and the rate of deformation. Also, concentrated fiber suspensions align more slowly with respect to strain than the Folgar-Tucker model predicts. Here, we borrow the technique of Wang et al. (2008) to incorporate this behavior in an objective fashion in this new model. Model parameters are selected by matching the experimental steady-state orientation in simple shear flow, and by requiring stable steady states and physically realizable solutions. Utilizing two separate techniques, we identify model parameters for three different materials. We then show that once a set of parameters that meets all previously established criteria has been identified, the differences in model behavior are negligible within that set of parameters. The final model with the proper parameter set is suitable for use in mold filling and other flow simulations, and does give improved predictions of fiber orientation for injection molded LFTs. Although significant fiber length degradation in LFTs has been observed both in literature and in this work, there are no quantitative fiber breakage models to predict either fiber length distributions or average fiber length measures. This work reviews the suspected causes of fiber breakage during the processing of discontinuously-reinforced thermoplastics, specifically LFTs, and introduces a phenomenological fiber breakage model based on the buckling force in a hydrodynamically loaded fiber. This breakage model is incorporated into a conservation equation for total fiber length, and a phenomenological model for the evolution of the fiber length distribution is developed. From this model, we also develop separate, approximate models for the evolution of both the number-average and weight-average fiber length measures. By applying these models to both a simple numerical example and a more complex mold-filling simulation, a qualitative agreement between experiment and prediction is observed. Although these results are promising, the breakage models have only been applied to the mold cavity in injection molding simulation. Both a literature review and our experimental data strongly suggest that the majority of fiber length degradation occurs in the earlier stages of injection molding, in the screw nozzle, runners, and gate. A better understanding of the melting and flow conditions upstream of the mold cavity, the simulation of which is beyond the scope of this work, is needed before these breakage models can be properly applied to the entire injection molding process. (Abstract shortened by UMI.)

Structural characterization and viscoelastic constitutive modeling of skin.

PubMed

Sherman, Vincent R; Tang, Yizhe; Zhao, Shiteng; Yang, Wen; Meyers, Marc A

2017-04-15

A fascinating material, skin has a tensile response which exhibits an extended toe region of minimal stress up to nominal strains that, in some species, exceed 1, followed by significant stiffening until a roughly linear region. The large toe region has been attributed to its unique structure, consisting of a network of curved collagen fibers. Investigation of the structure of rabbit skin reveals that it consists of layers of wavy fibers, each one with a characteristic orientation. Additionally, the existence of two preferred layer orientations is suggested based on the results of small angle X-ray scattering. These observations are used to construct a viscoelastic model consisting of collagen in two orientations, which leads to an in-plane anisotropic response. The structure-based model presented incorporates the elastic straightening and stretching of fibrils, their rotation towards the tensile axis, and the viscous effects which occur in the matrix of the skin due to interfibrillar and interlamellar sliding. The model is shown to effectively capture key features which dictate the mechanical response of skin. Examination by transmission and scanning electron microscopy of rabbit dermis enabled the identification of the key elements in its structure. The organization of collagen fibrils into flat fibers was identified and incorporated into a constitutive model that reproduces the mechanical response of skin. This enhanced quantitative predictive capability can be used in the design of synthetic skin and skin-like structures. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2016 First Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Lambert, Gregory

During the first quarter of FY 2016, the following technical progress has been made toward project milestones: 1) Virginia Tech completed fiber orientation (FO) measurements for the samples taken at Locations A, B, C and D (Figure 1) from the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed and non-ribbed complex parts using Virginia Tech’s established procedure. Virginia Tech delivered to PNNL all the measured fiber orientation data for validating ASMI fiber orientation predictions. 2)Virginia Tech performed fiber length distribution (FLD) measurements for the samples taken at Locations A, B, C and D from these complex parts using Virginia Tech’s established procedure.more » Virginia also re-assessed previous data and measured fiber length distributions in the corresponding nozzle purging materials and delivered to PNNL all the measured length data for validating ASMI fiber length predictions. 3)Based on measured fiber orientation data, Autodesk identified the parameters of the anisotropic rotary diffusion reduced strain closure (ARD-RSC) model [1] and provided PNNL with the values of these parameters that were used in ASMI analyses of the complex parts. 4) Magna provided Virginia Tech with additional samples cut out from the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed parts (Figure 1) for fiber length and orientation measurements. 5) In discussion with Autodesk, PNNL performed 3D ASMI analyses of the 30wt% LCF/PP and 30wt% LCF/PA66 ribbed and non-ribbed complex parts to predict fiber orientations and length distributions in these parts. The issues observed through the analyses regarding fiber orientation distributions profiles and abnormal length distributions were reported to Autodesk. Autodesk is working to resolve these issues. 6) PNNL completed 3D ASMI analyses of the complex parts and compared predicted fiber orientation results at Locations A, B, and C on the non-ribbed parts, and at Locations A, B, C and D on the ribbed parts with the corresponding measured data. PNNL also evaluated the within-15%-agreement criterion using the principal tensile and flexural moduli computed based on predicted vs. measured fiber orientation results. 7) PNNL developed and discussed with Toyota, Magna and PlastiComp a method to perform weight and cost reduction for making the 30wt% LCF/PA66 ribbed part through comparative three-point bending simulations of this part and of similar parts in steel.« less

Structured polarized light microscopy (SPLM) for mapping collagen fiber orientation of ocular tissues

NASA Astrophysics Data System (ADS)

Yang, Bin; Brazile, Bryn; Jan, Ning-Jiun; Voorhees, Andrew P.; Sigal, Ian A.

2018-02-01

Glaucoma is a disease characterized by progressive and irreversible vision loss leading to blindness. This vision loss is believed to be largely determined by the biomechanics of the optic nerve head region. Optic nerve head biomechanics, in turn, is determined by the properties of the constituent collagen. However, it is challenging to visualize and quantify collagen morphology and orientation in situ, and therefore often studies of the region collagen have used histological sections. Here we describe SPLM, a novel imaging technique that combines structured light illumination and polarized light microscopy (PLM) to enable collagen fiber visualization and fiber orientation mapping without requiring tissue sectioning. We developed a custom automated SPLM imaging system based on an upright microscope and a digital micromirror device (DMD) projector. The high spatial frequency patterns were used to achieve effective background suppression. Enhanced scattering sensitivity with SPLM resulted in images with highly improved visibility of collagen structures, even of tissues covered by pigment. SPLM produced improved fiber orientation maps from superficial layers compared to depth-averaged orientation from regular PLM. SPLM imaging provides valuable information of collagen fiber morphology and orientation in situ thus strengthening the study of ocular collagen fiber biomechanics and glaucoma.

Fiber Orientation Effects in Fused Filament Fabrication of Air-Cooled Heat Exchangers

NASA Astrophysics Data System (ADS)

Mulholland, T.; Goris, S.; Boxleitner, J.; Osswald, T. A.; Rudolph, N.

2018-03-01

Fused filament fabrication (FFF) is a type of additive manufacturing based on material extrusion that has long been considered a prototyping technology. However, the right application of material, process, and product can be used for manufacturing of end-use products, such as air-cooled heat exchangers made by adding fillers to the base polymer, enhancing the thermal conductivity. Fiber fillers lead to anisotropic thermal conductivity, which is governed by the process-induced fiber orientation. This article presents an experimental study on the microstructure-property relationship for carbon fiber-filled polyamide used in FFF. The fiber orientation is measured by micro-computed tomography, and the thermal conductivity of manufactured samples is measured. Although the thermal conductivity is raised by more than three times in the fiber orientation direction at a load of only 12 vol.%, the enhancement is low in the other directions, and this anisotropy, along with certain manufacturing restrictions, influences the final part performance.

Comparison of fiber orientation and tensile-stiffness orientation measurements in paper

Treesearch

David W. Vahey; John M. Considine; Andy Kahra; Mark Scotch

2008-01-01

We have had the opportunity to subject cross-machine paper strips from two mills to both ultrasound and optical "fiber-orientation" tests to examine the relationships between the results. Both determine an orientation angle, in degrees. Both measure sheet anisotropy as an MD/CD orientation ratio. The optical test has no counterpart to the ultrasonic...

Mapping cardiac fiber orientations from high-resolution DTI to high-frequency 3D ultrasound

NASA Astrophysics Data System (ADS)

Qin, Xulei; Wang, Silun; Shen, Ming; Zhang, Xiaodong; Wagner, Mary B.; Fei, Baowei

2014-03-01

The orientation of cardiac fibers affects the anatomical, mechanical, and electrophysiological properties of the heart. Although echocardiography is the most common imaging modality in clinical cardiac examination, it can only provide the cardiac geometry or motion information without cardiac fiber orientations. If the patient's cardiac fiber orientations can be mapped to his/her echocardiography images in clinical examinations, it may provide quantitative measures for diagnosis, personalized modeling, and image-guided cardiac therapies. Therefore, this project addresses the feasibility of mapping personalized cardiac fiber orientations to three-dimensional (3D) ultrasound image volumes. First, the geometry of the heart extracted from the MRI is translated to 3D ultrasound by rigid and deformable registration. Deformation fields between both geometries from MRI and ultrasound are obtained after registration. Three different deformable registration methods were utilized for the MRI-ultrasound registration. Finally, the cardiac fiber orientations imaged by DTI are mapped to ultrasound volumes based on the extracted deformation fields. Moreover, this study also demonstrated the ability to simulate electricity activations during the cardiac resynchronization therapy (CRT) process. The proposed method has been validated in two rat hearts and three canine hearts. After MRI/ultrasound image registration, the Dice similarity scores were more than 90% and the corresponding target errors were less than 0.25 mm. This proposed approach can provide cardiac fiber orientations to ultrasound images and can have a variety of potential applications in cardiac imaging.

3D Representative Volume Element Reconstruction of Fiber Composites via Orientation Tensor and Substructure Features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yi; Chen, Wei; Xu, Hongyi

To provide a seamless integration of manufacturing processing simulation and fiber microstructure modeling, two new stochastic 3D microstructure reconstruction methods are proposed for two types of random fiber composites: random short fiber composites, and Sheet Molding Compounds (SMC) chopped fiber composites. A Random Sequential Adsorption (RSA) algorithm is first developed to embed statistical orientation information into 3D RVE reconstruction of random short fiber composites. For the SMC composites, an optimized Voronoi diagram based approach is developed for capturing the substructure features of SMC chopped fiber composites. The proposed methods are distinguished from other reconstruction works by providing a way ofmore » integrating statistical information (fiber orientation tensor) obtained from material processing simulation, as well as capturing the multiscale substructures of the SMC composites.« less

A continuous process to align electrospun nanofibers into parallel and crossed arrays

NASA Astrophysics Data System (ADS)

Laudenslager, Michael J.; Sigmund, Wolfgang M.

2013-04-01

Electrical, optical, and mechanical properties of nanofibers are strongly affected by their orientation. Electrospinning is a nanofiber processing technique that typically produces nonwoven meshes of randomly oriented fibers. While several alignment techniques exist, they are only able to produce either a very thin layer of aligned fibers or larger quantities of fibers with less control over their alignment and orientation. The technique presented herein fills the gap between these two methods allowing one to produce thick meshes of highly oriented nanofibers. In addition, this technique is not limited to collection of fibers along a single axis. Modifications to the basic setup allow collection of crossed fibers without stopping and repositioning the apparatus. The technique works for a range of fiber sizes. In this study, fiber diameters ranged from 100 nm to 1 micron. This allows a few fibers at a time to rapidly deposit in alternating directions creating an almost woven structure. These aligned nanofibers have the potential to improve the performance of energy storage and thermoelectric devices and hold great promise for directed cell growth applications.

Functional grading of mineral and collagen in the attachment of tendon to bone.

PubMed

Genin, Guy M; Kent, Alistair; Birman, Victor; Wopenka, Brigitte; Pasteris, Jill D; Marquez, Pablo J; Thomopoulos, Stavros

2009-08-19

Attachment of dissimilar materials is a major challenge because high levels of localized stress may develop at their interfaces. An effective biologic solution to this problem exists at one of nature's most extreme interfaces: the attachment of tendon (a compliant, structural "soft tissue") to bone (a stiff, structural "hard tissue"). The goal of our study was to develop biomechanical models to describe how the tendon-to-bone insertion derives its mechanical properties. We examined the tendon-to-bone insertion and found two factors that give the tendon-to-bone transition a unique grading in mechanical properties: 1), a gradation in mineral concentration, measured by Raman spectroscopy; and 2), a gradation in collagen fiber orientation, measured by polarized light microscopy. Our measurements motivate a new physiological picture of the tissue that achieves this transition, the tendon-to-bone insertion, as a continuous, functionally graded material. Our biomechanical model suggests that the experimentally observed increase in mineral accumulation within collagen fibers can provide significant stiffening of the partially mineralized fibers, but only for concentrations of mineral above a "percolation threshold" corresponding to formation of a mechanically continuous mineral network within each collagen fiber (e.g., the case of mineral connectivity extending from one end of the fiber to the other). Increasing dispersion in the orientation distribution of collagen fibers from tendon to bone is a second major determinant of tissue stiffness. The combination of these two factors may explain the nonmonotonic variation of stiffness over the length of the tendon-to-bone insertion reported previously. Our models explain how tendon-to-bone attachment is achieved through a functionally graded material composition, and provide targets for tissue engineered surgical interventions and biomimetic material interfaces.

Fabrication of elastomeric silk fibers.

PubMed

Bradner, Sarah A; Partlow, Benjamin P; Cebe, Peggy; Omenetto, Fiorenzo G; Kaplan, David L

2017-09-01

Methods to generate fibers from hydrogels, with control over mechanical properties, fiber diameter, and crystallinity, while retaining cytocompatibility and degradability, would expand options for biomaterials. Here, we exploited features of silk fibroin protein for the formation of tunable silk hydrogel fibers. The biological, chemical, and morphological features inherent to silk were combined with elastomeric properties gained through enzymatic crosslinking of the protein. Postprocessing via methanol and autoclaving provided tunable control of fiber features. Mechanical, optical, and chemical analyses demonstrated control of fiber properties by exploiting the physical cross-links, and generating double network hydrogels consisting of chemical and physical cross-links. Structure and chemical analyses revealed crystallinity from 30 to 50%, modulus from 0.5 to 4 MPa, and ultimate strength 1-5 MPa depending on the processing method. Fabrication and postprocessing combined provided fibers with extensibility from 100 to 400% ultimate strain. Fibers strained to 100% exhibited fourth order birefringence, revealing macroscopic orientation driven by chain mobility. The physical cross-links were influenced in part by the drying rate of fabricated materials, where bound water, packing density, and microstructural homogeneity influenced cross-linking efficiency. The ability to generate robust and versatile hydrogel microfibers is desirable for bottom-up assembly of biological tissues and for broader biomaterial applications. © 2017 Wiley Periodicals, Inc.

Estimating cardiac fiber orientations in pig hearts using registered ultrasound and MR image volumes

NASA Astrophysics Data System (ADS)

Dormer, James D.; Meng, Yuguang; Zhang, Xiaodong; Jiang, Rong; Wagner, Mary B.; Fei, Baowei

2017-03-01

Heart fiber mechanics can be important predictors in current and future cardiac function. Accurate knowledge of these mechanics could enable cardiologists to provide a diagnosis before conditions progress. Magnetic resonance diffusion tensor imaging (MR-DTI) has been used to determine cardiac fiber orientations. Ultrasound is capable of providing anatomical information in real time, enabling a physician to quickly adjust parameters to optimize image scans. If known fiber orientations from a template heart measured using DTI can be accurately deformed onto a cardiac ultrasound volume, fiber orientations could be estimated for the patient without the need for a costly MR scan while still providing cardiologists valuable information about the heart mechanics. In this study, we apply the method to pig hearts, which are a close representation of human heart anatomy. Experiments from pig hearts show that the registration method achieved an average Dice similarity coefficient (DSC) of 0.819 +/- 0.050 between the ultrasound and deformed MR volumes and that the proposed ultrasound-based method is able to estimate the cardiac fiber orientation in pig hearts.

The melt-recrystallization behavior of highly oriented α-iPP fibers embedded in a HIPS matrix.

PubMed

Ye, Liwei; Li, Huihui; Qiu, Zhaobin; Yan, Shouke

2015-03-21

The melt-recrystallization behavior of α-iPP fibers embedded in an amorphous HIPS matrix has been studied by means of optical microscopy. The amorphous HIPS serving as a supporter of iPP fibers does not become involved in the nucleation and crystallization process of the molten highly oriented iPP fibers. It also does not provide any birefringence under the optical microscope with crossed polarizers. This enables the study of orientation-induced β-iPP crystallization through a control of the melting status of the fibers. Through melting the fibers at different temperatures above 175 °C and subsequent recrystallization, some β-iPP crystals were always produced. The content of the β-iPP crystal depends strongly on the melting temperature and melting time of the iPP fibers. It was confirmed that melting the iPP fibers at relatively lower temperature, e.g. 176 °C, less amount of β-iPP crystals were observed. The content of β-iPP crystal enhances first with increasing melting temperature and then decreases with further increase of the fiber melting temperature. The β-iPP crystallization is found to be most favorable upon melting the fibers at 178 °C for 2 min. This demonstrates the requirement of a certain chain or chain segment orientation for generating β-iPP crystallization on the one hand, while higher orientation of the iPP chains or chain segments encourages the growth of iPP crystals in the α-form on the other hand. This has been further confirmed by varying the melting time of the fiber at different temperatures, since relaxation of the iPP molecular chains at a fixed temperature is time dependent. Moreover, the complete transformation of α-iPP fibers in some local places into β-iPP crystals implies that the αβ-transition may not be required for the orientation-induced β-iPP crystallization.

Anisotropic mechanical behavior of an injection molded short fiber reinforced thermoplastic

NASA Astrophysics Data System (ADS)

Lopez, Delphine; Thuillier, Sandrine; Bessières, Nicolas; Grohens, Yves

2016-10-01

A short fiber reinforced thermoplastic was injected into a rectangular mold, in order to prepare samples to characterize the mechanical behavior of the material. The injection process was simulated with Moldflow and a cutting pattern was deduced from the predicted fiber orientation, leading to samples with several well-defined orientations with respect to the injection direction. Monotonic tensile tests up to rupture, as well as complex cycles made of loading steps followed by relaxation steps at different strain levels were performed, in order to check the reproducibility for a given orientation. Moreover, the fiber orientation in the central part of the tensile samples was also analyzed with X-ray tomography. The results show that the mechanical behavior for each orientation (among 6) was rather reproducible, thus validating the cutting pattern.

Cellulose as an Architectural Element in Spatially Structured Escherichia coli Biofilms

PubMed Central

Serra, Diego O.; Richter, Anja M.

2013-01-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of “nature and nurture” in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used “domesticated” E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by “repairing” a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this “de-domesticated” strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that—together with the cell-encasing curli fiber network and geometrical constraints in a growing colony—explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and “tissue-like” bacterial biofilms. PMID:24097954

Cellulose as an architectural element in spatially structured Escherichia coli biofilms.

PubMed

Serra, Diego O; Richter, Anja M; Hengge, Regine

2013-12-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of "nature and nurture" in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used "domesticated" E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by "repairing" a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this "de-domesticated" strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that-together with the cell-encasing curli fiber network and geometrical constraints in a growing colony-explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and "tissue-like" bacterial biofilms.

Computational modeling for prediction of the shear stress of three-dimensional isotropic and aligned fiber networks.

PubMed

Park, Seungman

2017-09-01

Interstitial flow (IF) is a creeping flow through the interstitial space of the extracellular matrix (ECM). IF plays a key role in diverse biological functions, such as tissue homeostasis, cell function and behavior. Currently, most studies that have characterized IF have focused on the permeability of ECM or shear stress distribution on the cells, but less is known about the prediction of shear stress on the individual fibers or fiber networks despite its significance in the alignment of matrix fibers and cells observed in fibrotic or wound tissues. In this study, I developed a computational model to predict shear stress for different structured fibrous networks. To generate isotropic models, a random growth algorithm and a second-order orientation tensor were employed. Then, a three-dimensional (3D) solid model was created using computer-aided design (CAD) software for the aligned models (i.e., parallel, perpendicular and cubic models). Subsequently, a tetrahedral unstructured mesh was generated and flow solutions were calculated by solving equations for mass and momentum conservation for all models. Through the flow solutions, I estimated permeability using Darcy's law. Average shear stress (ASS) on the fibers was calculated by averaging the wall shear stress of the fibers. By using nonlinear surface fitting of permeability, viscosity, velocity, porosity and ASS, I devised new computational models. Overall, the developed models showed that higher porosity induced higher permeability, as previous empirical and theoretical models have shown. For comparison of the permeability, the present computational models were matched well with previous models, which justify our computational approach. ASS tended to increase linearly with respect to inlet velocity and dynamic viscosity, whereas permeability was almost the same. Finally, the developed model nicely predicted the ASS values that had been directly estimated from computational fluid dynamics (CFD). The present computational models will provide new tools for predicting accurate functional properties and designing fibrous porous materials, thereby significantly advancing tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Architecturally defined scaffolds from synthetic collagen and elastin analogues for the fabrication of bioengineered tissues

NASA Astrophysics Data System (ADS)

Caves, Jeffrey Morris

The microstructure and mechanics of collagen and elastin protein fiber networks dictate the mechanical responses of all soft tissues and related organ systems. In this project, we endeavored to meet or exceed native tissue biomechanical properties through mimicry of these extracellular matrix components with synthetic collagen fiber and a recombinant elastin-like protein polymer. Significantly, this work led to the development of a framework for the design and fabrication of protein-based tissue substitutes with enhanced strength, resilience, anisotropy, and more. We began with the development of a spinning process for scalable production of synthetic collagen fiber. Fiber with an elliptical cross-section of 53 +/- 14 by 21 +/- 3 mum and an ultimate tensile strength of 90 +/- 19 MPa was continuously produced at 60 meters per hour from an ultrafiltered collagen solution. The starting collagen concentration, flowrate, and needle size could be adjusted to control fiber size. The fiber was characterized with mechanical analysis, micro-differential scanning calorimetry, transmission electron microscopy, second harmonic generation analysis, and subcutaneous murine implant. We subsequently describe the scalable, semi-automated fabrication of elastin-like protein sheets reinforced with synthetic collagen fibers that can be positioned in a precisely defined three-dimensional hierarchical pattern. Multilamellar, fiber-reinforced elastic protein sheets were constructed with controlled fiber orientation and volume fraction. Structures were analyzed with scanning electron microscopy, transmission electron microscopy, and digital volumetric imaging. The effect of fiber orientation and volume fraction on Young's Modulus, yield stress, ultimate tensile stress, strain-to-failure, and resilience was evaluated in uniaxial tension. Increased fiber volume fraction and alignment with applied deformation significantly increased Young's Modulus, resilience, and yield stress. Highly extensible, elastic tissues display a functionally important mechanical transition from low to high modulus deformation at a strain dictated by the crimped microstructure of native collagen fiber. We report the fabrication of dense arrays of microcrimped synthetic collagen fiber embedded in elastin-like protein lamellae that mimic this aspect of tissue mechanics. Microcrimped fiber arrays were characterized with scanning electron microscopy, confocal laser scanning microscopy, and uniaxial tension analysis. Crimp wavelength was 143 +/- 5 mum. The degree of crimping was varied from 3.1% to 9.4%, and corresponded to mechanical modulus transitions at 4.6% and 13.3% strain. Up to 1000 cycles of tensile loading did not substantially alter microcrimp morphology. We designed and prototyped a series of small-diameter vascular grafts consisting of elastin-like protein reinforced with controlled volume fractions and orientations of collagen fiber. A pressure-diameter system was developed and implemented to study the effects of fiber distribution on graft mechanics. The optimal design satisfied target properties with suture retention strength of 173 +/- 4 g-f, burst strength of 1483 +/- 143 mm Hg, and compliance of 5.1 +/- 0.8 %/100 mm Hg.

Electrodynamic tailoring of self-assembled three-dimensional electrospun constructs

NASA Astrophysics Data System (ADS)

Reis, Tiago C.; Correia, Ilídio J.; Aguiar-Ricardo, Ana

2013-07-01

The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters - deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity - were evaluated in an attempt to control material's design.The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters - deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity - were evaluated in an attempt to control material's design. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01668d

Chemical Stress Cracking of Acrylic Fibers.

DTIC Science & Technology

1982-05-01

stress, high fiber permeability, moderate fibe orientation, and water- plasticization . The proposed mechanism for bond cleava e involves cyclization of...tensile stress, high fiber permeability, moderate fiber orientation, and water- plasticization . The proposed mechanism for bond cleavage involves...chemical composition, plasticization , and other factors. It will be shown that the etching behavior does not reflect underlying hetero- geneities in the

A Ballistic Material Model for Cross-Plied Unidirectional Ultra-High Molecular-Weight Polyethylene Fiber-Reinforced Armor-Grade Composites

DTIC Science & Technology

2008-01-01

strength polymeric fibers such as aramid (e.g. Kevlar ®, Twaron®, etc.) or oriented polyethy- lene fibers (e.g. Spectra®, Dyneema®, etc.) with an... phenolic -poly-vinyl-butyral resin and on 0◦/90◦ cross- plied oriented polyethylene fiber-reinforced vinyl-ester resin are widely used in hard personnel...are: (a) poly-aramids (e.g. Kevlar ®, Twaron®, Technora®); (b) highly oriented ultra-highmolecular-weight polyethylene, UHMWPE (e.g. Spectra®, Dyneema

Investigation into the Fiber Orientation Effect on the Formability of GLARE Materials in the Stamp Forming Process

NASA Astrophysics Data System (ADS)

Liu, Shichen; Lang, Lihui; Sherkatghanad, Ehsan; Wang, Yao; Xu, Wencai

2018-04-01

Glass-reinforced aluminum laminate (GLARE) is a new class of fiber metal laminates (FMLs) which has the advantages such as high tensile strength, outstanding fatigue, impact resistance, and excellent corrosion properties. GLARE has been extensively applied in advanced aerospace and automobile industries. However, the deformation behavior of the glass fiber during forming must be studied to the benefits of the good-quality part we form. In this research, we focus on the effect of fiber layer orientation on the GLARE laminate formability in stamp forming process. Experimental and numerical analysis of stamping a hemisphere part in different fiber orientation is investigated. The results indicate that unidirectional and multi-directional fiber in the middle layer make a significant effect on the thinning and also surface forming quality of the three layer sheet. Furthermore, the stress-strain distribution of the aluminum alloy and the unique anisotropic property of the fiber layer exhibit that fiber layer orientation can also affect the forming depths as well as the fracture modes of the laminate. According to the obtained results, it is revealed that multi-directional fiber layers are a good alternative compared to the unidirectional fibers especially when a better formability is the purpose.

Path Planning Based on Ply Orientation Information for Automatic Fiber Placement on Mesh Surface

NASA Astrophysics Data System (ADS)

Pei, Jiazhi; Wang, Xiaoping; Pei, Jingyu; Yang, Yang

2018-03-01

This article introduces an investigation of path planning with ply orientation information for automatic fiber placement (AFP) on open-contoured mesh surface. The new method makes use of the ply orientation information generated by loading characteristics on surface, divides the surface into several zones according to the ply orientation information and then designs different fiber paths in different zones. This article also gives new idea of up-layer design in order to make up for defects between parts and improve product's strength.

A micro-scale cutting model for UD CFRP composites with thermo-mechanical coupling

DOE PAGES

Cheng, Hui; Gao, Jiaying; Kafka, Orion Landauer; ...

2017-09-23

Cutting a unidirectional carbon fiber-reinforced polymer (UD CFRP) structure is the basic unit for CFRP machining, which is a complex thermal-mechanically coupled process. To reveal the deformation mechanism and predict cutting force in UD CFRP micro cutting, a micro-scale fracture model for UD CFRP cutting with thermal-mechanical coupling is demonstrated in this paper, which captures the failure modes for fibers, matrix and the interface based on a micro-level RVE using a relatively simple damage based fracture method. The thermal-mechanical coupling model at the micro scale is developed on the basis of the plastic energy dissipation and frictional heating during cutting.more » Failure models for the fiber, matrix and interface region are applied depending on the material properties of each of these three phases. Numerical simulations based on the above model with different fiber orientations were performed to predict the deformation and forces of different components in UD CFRP. Cutting experiments with the same fiber orientations as considered in the simulations were carried out to validate the force and deformation results. The predicted force and deformation patterns match well with evidence from our experiments. In general, the cutting force is larger than the thrust force regardless of fiber orientation. The cutting force reaches a maximum as the fiber orientation approaches 90 , but thrust forces do not vary substantially across cases. When the fiber orientation is acute, the deformation of fibers is much smaller than when the cutting angle is obtuse. Surface roughness follows the same trend with cutting angle as fiber deformation.« less

A micro-scale cutting model for UD CFRP composites with thermo-mechanical coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Hui; Gao, Jiaying; Kafka, Orion Landauer

Cutting a unidirectional carbon fiber-reinforced polymer (UD CFRP) structure is the basic unit for CFRP machining, which is a complex thermal-mechanically coupled process. To reveal the deformation mechanism and predict cutting force in UD CFRP micro cutting, a micro-scale fracture model for UD CFRP cutting with thermal-mechanical coupling is demonstrated in this paper, which captures the failure modes for fibers, matrix and the interface based on a micro-level RVE using a relatively simple damage based fracture method. The thermal-mechanical coupling model at the micro scale is developed on the basis of the plastic energy dissipation and frictional heating during cutting.more » Failure models for the fiber, matrix and interface region are applied depending on the material properties of each of these three phases. Numerical simulations based on the above model with different fiber orientations were performed to predict the deformation and forces of different components in UD CFRP. Cutting experiments with the same fiber orientations as considered in the simulations were carried out to validate the force and deformation results. The predicted force and deformation patterns match well with evidence from our experiments. In general, the cutting force is larger than the thrust force regardless of fiber orientation. The cutting force reaches a maximum as the fiber orientation approaches 90 , but thrust forces do not vary substantially across cases. When the fiber orientation is acute, the deformation of fibers is much smaller than when the cutting angle is obtuse. Surface roughness follows the same trend with cutting angle as fiber deformation.« less

Nondestructive imaging of fiber structure in articular cartilage using optical polarization tractography

NASA Astrophysics Data System (ADS)

Yao, Xuan; Wang, Yuanbo; Ravanfar, Mohammadreza; Pfeiffer, Ferris M.; Duan, Dongsheng; Yao, Gang

2016-11-01

Collagen fiber orientation plays an important role in determining the structure and function of the articular cartilage. However, there is currently a lack of nondestructive means to image the fiber orientation from the cartilage surface. The purpose of this study is to investigate whether the newly developed optical polarization tractography (OPT) can image fiber structure in articular cartilage. OPT was applied to obtain the depth-dependent fiber orientation in fresh articular cartilage samples obtained from porcine phalanges. For comparison, we also obtained collagen fiber orientation in the superficial zone of the cartilage using the established split-line method. The direction of each split-line was quantified using image processing. The orientation measured in OPT agreed well with those obtained from the split-line method. The correlation analysis of a total of 112 split-lines showed a greater than 0.9 coefficient of determination (R2) between the split-line results and OPT measurements obtained between 40 and 108 μm in depth. In addition, the thickness of the superficial layer can also be assessed from the birefringence images obtained in OPT. These results support that OPT provides a nondestructive way to image the collagen fiber structure in articular cartilage. This technology may be valuable for both basic cartilage research and clinical orthopedic applications.

Extracting three-dimensional orientation and tractography of myofibers using optical coherence tomography

PubMed Central

Gan, Yu; Fleming, Christine P.

2013-01-01

Abnormal changes in orientation of myofibers are associated with various cardiac diseases such as arrhythmia, irregular contraction, and cardiomyopathy. To extract fiber information, we present a method of quantifying fiber orientation and reconstructing three-dimensional tractography of myofibers using optical coherence tomography (OCT). A gradient based algorithm was developed to quantify fiber orientation in three dimensions and particle filtering technique was employed to track myofibers. Prior to image processing, three-dimensional image data set were acquired from all cardiac chambers and ventricular septum of swine hearts using OCT system without optical clearing. The algorithm was validated through rotation test and comparison with manual measurements. The experimental results demonstrate that we are able to visualize three-dimensional fiber tractography in myocardium tissues. PMID:24156071

Modeling and simulation of the data communication network at the ASRM Facility

NASA Technical Reports Server (NTRS)

Nirgudkar, R. P.; Moorhead, R. J.; Smith, W. D.

1994-01-01

This paper describes the modeling and simulation of the communication network for the NASA Advanced Solid Rocket Motor (ASRM) facility under construction at Yellow Creek near Luka, Mississippi. Manufacturing, testing, and operations at the ASRM site will be performed in different buildings scattered over an 1800 acre site. These buildings are interconnected through a local area network (LAN), which will contain one logical Fiber Distributed Data Interface (FDDI) ring acting as a backbone for the whole complex. The network contains approximately 700 multi-vendor workstations, 22 multi-vendor workcells, and 3 VAX clusters interconnected via Ethernet and FDDI. The different devices produce appreciably different traffic patterns, each pattern will be highly variable, and some patterns will be very bursty. Most traffic is between the VAX clusters and the other devices. Comdisco's Block Oriented Network Simulator (BONeS) has been used for network simulation. The two primary evaluation parameters used to judge the expected network performance are throughput and delay.

Numerical prediction of flow induced fibers orientation in injection molded polymer composites

NASA Astrophysics Data System (ADS)

Oumer, A. N.; Hamidi, N. M.; Mat Sahat, I.

2015-12-01

Since the filling stage of injection molding process has important effect on the determination of the orientation state of the fibers, accurate analysis of the flow field for the mold filling stage becomes a necessity. The aim of the paper is to characterize the flow induced orientation state of short fibers in injection molding cavities. A dog-bone shaped model is considered for the simulation and experiment. The numerical model for determination of the fibers orientation during mold-filling stage of injection molding process was solved using Computational Fluid Dynamics (CFD) software called MoldFlow. Both the simulation and experimental results showed that two different regions (or three layers of orientation structures) across the thickness of the specimen could be found: a shell region which is near to the mold cavity wall, and a core region at the middle of the cross section. The simulation results support the experimental observations that for thin plates the probability of fiber alignment to the flow direction near the mold cavity walls is high but low at the core region. It is apparent that the results of this study could assist in decisions regarding short fiber reinforced polymer composites.

Muscle Fiber Orientation Angle Dependence of the Tensile Fracture Behavior of Frozen Fish Muscle

NASA Astrophysics Data System (ADS)

Hagura, Yoshio; Okamoto, Kiyoshi; Suzuki, Kanichi; Kubota, Kiyoshi

We have proposed a new cutting method for frozen fish named "cryo-cutting". This method applied tensile fracture force or bending fracture force to the frozen fish at appropriate low temperatures. In this paper, to clarify cryo-cutting mechanism, we analyzed tensile fracture behavior of the frozen fish muscle. In the analysis, the frozen fish muscle was considered unidirectionally fiber-reinforced composite material which consisted of fiber (muscle fiber) and matrix (connective tissue). Fracture criteria (maximum stress criterion, Tsai-Hill criterion) for the unidirectionally fiber-reinforced composite material were used. The following results were obtained: (1) By using Tsai-Hill criterion, muscle fiber orientation angle dependence of the tensile fracture stress could be calculated. (2) By using the maximum stress theory jointly with Tsai-Hill criterion, muscle fiber orientation angle dependence of the fracture mode of the frozen fish muscle could be estimated.

Shear-induced migration and orientation of rigid fibers

NASA Astrophysics Data System (ADS)

Butler, Jason; Strednak, Scott; Shaikh, Saif; Guazzelli, Elisabeth

2017-11-01

The spatial and orientation distributions are measured for a suspension of fibers during pressure-driven flow. The fibers are rigid and non-colloidal, and two aspect ratios (length to diameter ratios) of 12 and 24 were tested; the suspending fluid is viscous, Newtonian, and density matched to the particles. As with the migration of spheres in parabolic flows, the fibers migrate toward the centerline of the channel if the concentration is sufficiently high. Migration is not observed for concentrations below a volume fraction of 0.035 for aspect ratio 24 and 0.07 for aspect ratio 12. The orientation distribution of the fibers is spatially dependent. Fibers near the center of the channel align closely with the flow direction, but fibers near the wall are observed to preferentially align in the vorticity (perpendicular to the flow and gradient) direction. National Science Foundation (Grants #1511787 and #1362060).

Sparse Solution of Fiber Orientation Distribution Function by Diffusion Decomposition

PubMed Central

Yeh, Fang-Cheng; Tseng, Wen-Yih Isaac

2013-01-01

Fiber orientation is the key information in diffusion tractography. Several deconvolution methods have been proposed to obtain fiber orientations by estimating a fiber orientation distribution function (ODF). However, the L 2 regularization used in deconvolution often leads to false fibers that compromise the specificity of the results. To address this problem, we propose a method called diffusion decomposition, which obtains a sparse solution of fiber ODF by decomposing the diffusion ODF obtained from q-ball imaging (QBI), diffusion spectrum imaging (DSI), or generalized q-sampling imaging (GQI). A simulation study, a phantom study, and an in-vivo study were conducted to examine the performance of diffusion decomposition. The simulation study showed that diffusion decomposition was more accurate than both constrained spherical deconvolution and ball-and-sticks model. The phantom study showed that the angular error of diffusion decomposition was significantly lower than those of constrained spherical deconvolution at 30° crossing and ball-and-sticks model at 60° crossing. The in-vivo study showed that diffusion decomposition can be applied to QBI, DSI, or GQI, and the resolved fiber orientations were consistent regardless of the diffusion sampling schemes and diffusion reconstruction methods. The performance of diffusion decomposition was further demonstrated by resolving crossing fibers on a 30-direction QBI dataset and a 40-direction DSI dataset. In conclusion, diffusion decomposition can improve angular resolution and resolve crossing fibers in datasets with low SNR and substantially reduced number of diffusion encoding directions. These advantages may be valuable for human connectome studies and clinical research. PMID:24146772

Implementation of New Process Models for Tailored Polymer Composite Structures into Processing Software Packages

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Jin, Xiaoshi; Wang, Jin

2010-02-23

This report describes the work conducted under the Cooperative Research and Development Agreement (CRADA) (Nr. 260) between the Pacific Northwest National Laboratory (PNNL) and Autodesk, Inc. to develop and implement process models for injection-molded long-fiber thermoplastics (LFTs) in processing software packages. The structure of this report is organized as follows. After the Introduction Section (Section 1), Section 2 summarizes the current fiber orientation models developed for injection-molded short-fiber thermoplastics (SFTs). Section 3 provides an assessment of these models to determine their capabilities and limitations, and the developments needed for injection-molded LFTs. Section 4 then focuses on the development of amore » new fiber orientation model for LFTs. This model is termed the anisotropic rotary diffusion - reduced strain closure (ARD-RSC) model as it explores the concept of anisotropic rotary diffusion to capture the fiber-fiber interaction in long-fiber suspensions and uses the reduced strain closure method of Wang et al. to slow down the orientation kinetics in concentrated suspensions. In contrast to fiber orientation modeling, before this project, no standard model was developed to predict the fiber length distribution in molded fiber composites. Section 5 is therefore devoted to the development of a fiber length attrition model in the mold. Sections 6 and 7 address the implementations of the models in AMI, and the conclusions drawn from this work is presented in Section 8.« less

A multiscale approach for the reconstruction of the fiber architecture of the human brain based on 3D-PLI

PubMed Central

Reckfort, Julia; Wiese, Hendrik; Pietrzyk, Uwe; Zilles, Karl; Amunts, Katrin; Axer, Markus

2015-01-01

Structural connectivity of the brain can be conceptionalized as a multiscale organization. The present study is built on 3D-Polarized Light Imaging (3D-PLI), a neuroimaging technique targeting the reconstruction of nerve fiber orientations and therefore contributing to the analysis of brain connectivity. Spatial orientations of the fibers are derived from birefringence measurements of unstained histological sections that are interpreted by means of a voxel-based analysis. This implies that a single fiber orientation vector is obtained for each voxel, which reflects the net effect of all comprised fibers. We have utilized two polarimetric setups providing an object space resolution of 1.3 μm/px (microscopic setup) and 64 μm/px (macroscopic setup) to carry out 3D-PLI and retrieve fiber orientations of the same tissue samples, but at complementary voxel sizes (i.e., scales). The present study identifies the main sources which cause a discrepancy of the measured fiber orientations observed when measuring the same sample with the two polarimetric systems. As such sources the differing optical resolutions and diverging retardances of the implemented waveplates were identified. A methodology was implemented that enables the compensation of measured different systems' responses to the same birefringent sample. This opens up new ways to conduct multiscale analysis in brains by means of 3D-PLI and to provide a reliable basis for the transition between different scales of the nerve fiber architecture. PMID:26388744

Feasibility on fiber orientation detection on unidirectional CFRP composite laminates using nondestructive evaluation techniques

NASA Astrophysics Data System (ADS)

Yang, In-Young; Kim, Ji-Hoon; Cha, Cheon-Seok; Lee, Kil-Sung; Hsu, David K.; Im, Kwang-Hee

2007-07-01

In particular, CFRP (carbon fiber reinforced plastics) composite materials have found wide applicability because of their inherent design flexibility and improved material properties. CFRP composites were manufactured from uni-direction prepreg sheet in this paper. It is important to assess fiber orientation, material properties and part defect in order to ensure product quality and structural integrity of CFRP because strength and stiffness of composites depend on fiber orientation. It is desirable to perform nondestructive evaluation which is very beneficial. An new method for nondestructively determining the fiber orientation in a composite laminate is presented. A one-sided pitch-catch setup was used in the detection and evaluation of flaws and material anomalies in the unidirectional CFRP composite laminates. Two Rayleigh wave transducers were joined head-to-head and used in the pitch-catch mode on the surface of the composites. The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composite. Especially, ultrasonic waves were extensively characterized in the CFRP composite laminates both normal to fiber and along to fiber with using a one-sided direction of Rayleigh wave transducers. Also, one-sided ultrasonic measurement was made with using a Rayleigh wave transducers and a conventional scanner was used in an immersion tank for extracting fiber orientation information from the ultrasonic reflection in the unidirectional laminate. Therefore, it is thought that the proposed method is useful to evaluate integrity of CFRP laminates.

bFGF-containing electrospun gelatin scaffolds with controlled nano-architectural features for directed angiogenesis

PubMed Central

Montero, Ramon B.; Vial, Ximena; Nguyen, Dat Tat; Farhand, Sepehr; Reardon, Mark; Pham, Si M.; Tsechpenakis, Gavriil; Andreopoulos, Fotios M.

2011-01-01

Current therapeutic angiogenesis strategies are focused on the development of biologically responsive scaffolds that can deliver multiple angiogenic cytokines and/or cells in ischemic regions. Herein, we report on a novel electrospinning approach to fabricate cytokine-containing nanofibrous scaffolds with tunable architecture to promote angiogenesis. Fiber diameter and uniformity were controlled by varying the concentration of the polymeric (i.e. gelatin) solution, the feed rate, needle to collector distance, and electric field potential between the collector plate and injection needle. Scaffold fiber orientation (random vs. aligned) was achieved by alternating the polarity of two parallel electrodes placed on the collector plate thus dictating fiber deposition patterns. Basic fibroblast growth factor (bFGF) was physically immobilized within the gelatin scaffolds at variable concentrations and human umbilical vein endothelial cells (HUVEC) were seeded on the top of the scaffolds. Cell proliferation and migration was assessed as a function of growth factor loading and scaffold architecture. HUVECs successfully adhered onto gelatin B scaffolds and cell proliferation was directly proportional to the loading concentrations of the growth factor (0–100 bFGF ng/mL). Fiber orientation had a pronounced effect on cell morphology and orientation. Cells were spread along the fibers of the electrospun scaffolds with the aligned orientation and developed a spindle-like morphology parallel to the scaffold's fibers. In contrast, cells seeded onto the scaffolds with random fiber orientation, did not demonstrate any directionality and appeared to have a rounder shape. Capillary formation (i.e. sprouts length and number of sprouts per bead), assessed in a 3-D in vitro angiogenesis assay, was a function of bFGF loading concentration (0 ng, 50 ng and 100 ng per scaffold) for both types of electrospun scaffolds (i.e. with aligned or random fiber orientation). PMID:22200610

Orientation-dependent fiber-optic accelerometer based on grating inscription over fiber cladding.

PubMed

Rong, Qiangzhou; Qiao, Xueguang; Guo, Tuan; Bao, Weijia; Su, Dan; Yang, Hangzhou

2014-12-01

An orientation-sensitive fiber-optic accelerometer based on grating inscription over fiber cladding has been demonstrated. The sensor probe comprises a compact structure in which a short section of thin-core fiber (TCF) stub containing a "cladding" fiber Bragg grating (FBG) is spliced to another single-mode fiber (SMF) without any lateral offset. A femtosecond laser side-illumination technique was utilized to ensure that the grating inscription remains close to the core-cladding interface of the TCF. The core mode and the cladding mode of the TCF are coupled at the core-mismatch junction, and two well-defined resonances in reflection appear from the downstream FBG, in which the cladding resonance exhibits a strong polarization and bending dependence due to the asymmetrical distribution of the cladding FBG along the fiber cross section. Strong orientation dependence of the vibration (acceleration) measurement has been achieved by power detection of the cladding resonance. Meanwhile, the unwanted power fluctuations and temperature perturbations can be referenced out by monitoring the fundamental core resonance.

Anisotropic x-ray scattering and orientation fields in cardiac tissue cells

NASA Astrophysics Data System (ADS)

Bernhardt, M.; Nicolas, J.-D.; Eckermann, M.; Eltzner, B.; Rehfeldt, F.; Salditt, T.

2017-01-01

X-ray diffraction from biomolecular assemblies is a powerful technique which can provide structural information about complex architectures such as the locomotor systems underlying muscle contraction. However, in its conventional form, macromolecular diffraction averages over large ensembles. Progress in x-ray optics has now enabled to probe structures on sub-cellular scales, with the beam confined to a distinct organelle. Here, we use scanning small angle x-ray scattering (scanning SAXS) to probe the diffraction from cytoskeleton networks in cardiac tissue cells. In particular, we focus on actin-myosin composites, which we identify as the dominating contribution to the anisotropic diffraction patterns, by correlation with optical fluorescence microscopy. To this end, we use a principal component analysis approach to quantify direction, degree of orientation, nematic order, and the second moment of the scattering distribution in each scan point. We compare the fiber orientation from micrographs of fluorescently labeled actin fibers to the structure orientation of the x-ray dataset and thus correlate signals of two different measurements: the native electron density distribution of the local probing area versus specifically labeled constituents of the sample. Further, we develop a robust and automated fitting approach based on a power law expansion, in order to describe the local structure factor in each scan point over a broad range of the momentum transfer {q}{{r}}. Finally, we demonstrate how the methodology shown for freeze dried cells in the first part of the paper can be translated to alive cell recordings.

Effect of glass fiber surface treatments on mechanical strength of epoxy based composite materials.

PubMed

Iglesias, J G; González-Benito, J; Aznar, A J; Bravo, J; Baselga, J

2002-06-01

Sizing glass fibers with silane coupling agents enhances the adhesion and the durability of the fiber/polymer matrix interface in composite materials. There are several tests to determine the interfacial strength between a fiber and resin, but all of them present difficulties in interpreting the results and/or sample preparation. In this study, we observed the influence of different aminosilanes fiber coatings on the resistance of epoxy-based composite materials using a very easy fractographic test. In addition, we tried a new fluorescence method to get information on a molecular level precisely at the interface. Strength was taken into account from two standpoints: (i) mechanical strength and (ii) the resistance to hydrolysis of the interface in oriented glass-reinforced epoxy-based composites. Three silanes: gamma-aminopropyltriethoxysilane, gamma-Aminopropylmethyldiethoxysilane, and gamma-Aminopropyldimethylethoxysilane were used to obtain different molecular structures at the interface. It was concluded that: (i) the more accessible amine groups are, the higher the interface rigidity is; (ii) an interpenetrating network mechanism seems to be the most important for adhesion and therefore to the interfacial strength; and (iii) the higher the degree of crosslinking in the silane coupling layer is, the higher the hydrolytic damage rate is.

Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.

2006-11-30

This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our objective is to assess these models in order to determine their capabilities and limitations, and the developments needed for long-fiber injection-molded thermoplastics (LFTs). First, the concentration regimes are summarized to facilitate the understandingmore » of different types of fiber-fiber interaction that can occur for a given fiber volume fraction. After the formulation of the fiber suspension flow problem and the simplification leading to the Hele-Shaw approach, the interaction mechanisms are discussed. Next, the establishment of the rheological constitutive equation is presented that reflects the coupled flow/orientation nature. The decoupled flow/orientation approach is also discussed which constitutes a good simplification for many applications involving flows in thin cavities. Finally, before outlining the necessary developments for LFTs, some applications of the current orientation model and the so-called modified Folgar-Tucker model are illustrated through the fiber orientation predictions for selected LFT samples.« less

Molecular Orientation in Dry and Hydrated Cellulose Fibers: A Coherent Anti-Stokes Raman Scattering Microscopy Study

PubMed Central

Zimmerley, Maxwell; Younger, Rebecca; Valenton, Tiffany; Oertel, David C.; Ward, Jimmie L.; Potma, Eric O.

2012-01-01

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with spontaneous Raman scattering microspectroscopy and second harmonic generation (SHG) microscopy to interrogate the molecular alignment in dry and hydrated cellulose fibers. Two types of cellulose were investigated: natural cellulose I in cotton fibers and regenerated cellulose II in rayon fibers. On the basis of the orientation of the methylene symmetric stretching vibration, the molecular alignment of cellulose microfibrils is found to be conserved on the micrometer scale. Whereas the molecular orientation in cotton shows modest variability along the fiber, the alignment of the cellulose units in rayon is highly consistent throughout the fiber. The ordered alignment is retained upon fiber hydration. Upon hydration of the cellulose fibers, an anisotropic electronic contribution is observed, which indicates an ordered incorporation of water molecules into the fiber structure. The third-order and second-order electronic polarizability of cellulose I are directed along the axis of the polyglucan chain. No second-order optical response is observed in cellulose II, supporting the antiparallel arrangement of the polyglucan chains in regenerated cellulose. PMID:20684644

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 2: Fiber optic technology and long distance networks

NASA Astrophysics Data System (ADS)

1986-10-01

The study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the Executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 2: Fiber optic technology and long distance networks

NASA Technical Reports Server (NTRS)

1986-01-01

The study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the Executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

Register cardiac fiber orientations from 3D DTI volume to 2D ultrasound image of rat hearts

NASA Astrophysics Data System (ADS)

Qin, Xulei; Wang, Silun; Shen, Ming; Zhang, Xiaodong; Lerakis, Stamatios; Wagner, Mary B.; Fei, Baowei

2015-03-01

Two-dimensional (2D) ultrasound or echocardiography is one of the most widely used examinations for the diagnosis of cardiac diseases. However, it only supplies the geometric and structural information of the myocardium. In order to supply more detailed microstructure information of the myocardium, this paper proposes a registration method to map cardiac fiber orientations from three-dimensional (3D) magnetic resonance diffusion tensor imaging (MR-DTI) volume to the 2D ultrasound image. It utilizes a 2D/3D intensity based registration procedure including rigid, log-demons, and affine transformations to search the best similar slice from the template volume. After registration, the cardiac fiber orientations are mapped to the 2D ultrasound image via fiber relocations and reorientations. This method was validated by six images of rat hearts ex vivo. The evaluation results indicated that the final Dice similarity coefficient (DSC) achieved more than 90% after geometric registrations; and the inclination angle errors (IAE) between the mapped fiber orientations and the gold standards were less than 15 degree. This method may provide a practical tool for cardiologists to examine cardiac fiber orientations on ultrasound images and have the potential to supply additional information for diagnosis of cardiac diseases.

The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

NASA Astrophysics Data System (ADS)

Youssefi, Mostafa; Safaie, Banafsheh

2018-06-01

Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

NASA Astrophysics Data System (ADS)

Youssefi, Mostafa; Safaie, Banafsheh

2018-01-01

Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

Nanoscale Morphology to Macroscopic Performance in Ultra High Molecular Weight Polyethylene Fibers

NASA Astrophysics Data System (ADS)

McDaniel, Preston B.

Ultra high molecular weight polyethylene (UHMWPE) fibers are increasingly used in high -performance applications where strength, stiffness, and the ability to dissipate energy are of critical importance. Despite their use in a variety of applications, the influence of morphological features at the meso/nanoscale on the macroscopic performance of the fibers has not been well understood. There is particular interest in gaining a better understanding of the nanoscale structure-property relationships in UHMWPE fibers used in ballistics applications. In order to accurately model and predict failure in the fiber, a more complete understanding of the complex load pathways that dictate the ways in which load is transferred through the fiber, across interfaces and length scales is required. The goal of the work discussed herein is to identify key meso/nanostructural features evolved in high performance fibers and determine how these features influence the performance of the fiber through a variety of different loading mechanisms. The important structural features in high-performance UHMWPE fibers are first identified through examination of the meso/nanostructure of a series of fibers with different processing conditions. This is achieved primarily through the use of wide-angle x-ray diffraction (WAXD) and atomic force microscopy (AFM). Analysis of AFM images and WAXD data allows identification and quantifications of important structural features at these length scales. Key meso/nanostructural features are then examined with respect to their influence on the transverse compression behavior of single fibers. Through post-mortem AFM analysis of samples at incremental compressive strains, the evolution of damage is examined and compared with macroscopic fiber mechanical response. It was found that collapse of mesoscale voids, followed by nanoscale fibrillation and reorganization of a fibrillar network has a significant influence on the mechanical response of the fiber. Through this work, the importance of nanoscale fibril adhesive interactions is highlighted. However, very little information exists in the literature as to the nature and magnitude of these interactions. Examination of nanoscale fibrillar adhesive interactions is experimentally difficult, and necessitated the development of an AFM based nanoscale splitting technique to quantify the interactions between fibrils. Through analysis of split geometry and careful partitioning of energies, the adhesive energy between fibrils in UHMWPE fibers are determined. The calculated average adhesive energies are significantly larger than the estimated energy due to van der Waals interactions, suggesting that there are physical connections (e.g., tie chains, tie fibrils, and lamellar crystalline bridges) that influence the interactions between fibrils. The interactions identified through this work are believed to be responsible for the creation of load pathways across fibril interfaces where load may be translated through the fiber in tension, compression, and shear. Finally, the nature of the mesoscale fibrillar network is explored through the development of a variable angle, single fiber peel test. This peel test enables the quantification of Mode I and Mode II peel energies. The modes of deformation observed in the peel test are representative of the mechanisms experienced during tensile and transverse compression loading. The quantification of peel energies in both Mode I and Mode II failure highlight the importance of the fibrillar network as a key mechanism for the translation of load through the fiber. In both modes of failure, the fibril network acts as a framework for the orientation and subsequent failure of nanoscale fibrils.

Polarization-resolved second-harmonic-generation imaging of photoaged dermal collagen fiber

NASA Astrophysics Data System (ADS)

Yasui, Takeshi; Takahashi, Yu; Araki, Tsutomu

2009-02-01

Polarization-resolved second-harmonic-generation (SHG) microscopy is useful for assessment of collagen fiber orientation in tissues. In this paper, we investigated the relation between wrinkle direction and collagen orientation in ultraviolet-B-exposed (UVB-exposed) skin using polarization-resolved SHG microscopy. A polarization anisotropic image of the SHG light indicated that wrinkle direction in UVB-exposed skin is predominantly parallel to the orientation of dermal collagen fibers whereas no-UVB-exposed skin was dominated by collagen orientation parallel to the meridian line of body. The method proposed has the potential to become a powerful non-invasive tool for assessment of cutaneous photoaging.

High capacity fiber optic sensor networks using hybrid multiplexing techniques and their applications

NASA Astrophysics Data System (ADS)

Sun, Qizhen; Li, Xiaolei; Zhang, Manliang; Liu, Qi; Liu, Hai; Liu, Deming

2013-12-01

Fiber optic sensor network is the development trend of fiber senor technologies and industries. In this paper, I will discuss recent research progress on high capacity fiber sensor networks with hybrid multiplexing techniques and their applications in the fields of security monitoring, environment monitoring, Smart eHome, etc. Firstly, I will present the architecture of hybrid multiplexing sensor passive optical network (HSPON), and the key technologies for integrated access and intelligent management of massive fiber sensor units. Two typical hybrid WDM/TDM fiber sensor networks for perimeter intrusion monitor and cultural relics security are introduced. Secondly, we propose the concept of "Microstructure－Optical X Domin Refecltor (M-OXDR)" for fiber sensor network expansion. By fabricating smart micro-structures with the ability of multidimensional encoded and low insertion loss along the fiber, the fiber sensor network of simple structure and huge capacity more than one thousand could be achieved. Assisted by the WDM/TDM and WDM/FDM decoding methods respectively, we built the verification systems for long-haul and real-time temperature sensing. Finally, I will show the high capacity and flexible fiber sensor network with IPv6 protocol based hybrid fiber/wireless access. By developing the fiber optic sensor with embedded IPv6 protocol conversion module and IPv6 router, huge amounts of fiber optic sensor nodes can be uniquely addressed. Meanwhile, various sensing information could be integrated and accessed to the Next Generation Internet.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-06-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-05-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

High speed bus technology development

NASA Astrophysics Data System (ADS)

Modrow, Marlan B.; Hatfield, Donald W.

1989-09-01

The development and demonstration of the High Speed Data Bus system, a 50 Million bits per second (Mbps) local data network intended for avionics applications in advanced military aircraft is described. The Advanced System Avionics (ASA)/PAVE PILLAR program provided the avionics architecture concept and basic requirements. Designs for wire and fiber optic media were produced and hardware demonstrations were performed. An efficient, robust token-passing protocol was developed and partially demonstrated. The requirements specifications, the trade-offs made, and the resulting designs for both a coaxial wire media system and a fiber optics design are examined. Also, the development of a message-oriented media access protocol is described, from requirements definition through analysis, simulation and experimentation. Finally, the testing and demonstrations conducted on the breadboard and brassboard hardware is presented.

Quantifying collagen orientation in breast tissue biopsies using SLIM (Conference Presentation)

NASA Astrophysics Data System (ADS)

Majeed, Hassaan; Okoro, Chukwuemeka; Balla, Andre; Toussaint, Kimani C.; Popescu, Gabriel

2017-02-01

Breast cancer is a major public health problem worldwide, being the most common type of cancer among women according to the World Health Organization (WHO). The WHO has further stressed the importance of an early determination of the disease course through prognostic markers. Recent studies have shown that the alignment of collagen fibers in tumor adjacent stroma correlate with poorer health outcomes in patients. Such studies have typically been carried out using Second-Harmonic Generation (SHG) microscopy. SHG images are very useful for quantifying collagen fiber orientation due their specificity to non-centrosymmetric structures in tissue, leading to high contrast in collagen rich areas. However, the imaging throughput in SHG microscopy is limited by its point scanning geometry. In this work, we show that SLIM, a wide-field high-throughput QPI technique, can be used to obtain the same information on collagen fiber orientation as is obtainable through SHG microscopy. We imaged a tissue microarray containing both benign and malignant cores using both SHG microscopy and SLIM. The cellular (non-collagenous) structures in the SLIM images were next segmented out using an algorithm developed in-house. Using the previously published Fourier Transform Second Harmonic Generation (FT-SHG) tool, the fiber orientations in SHG and segmented SLIM images were then quantified. The resulting histograms of fiber orientation angles showed that both SHG and SLIM generate similar measurements of collagen fiber orientation. The SLIM modality, however, can generate these results at much higher throughput due to its wide-field, whole-slide scanning capabilities.

Leading non-Gaussian corrections for diffusion orientation distribution function.

PubMed

Jensen, Jens H; Helpern, Joseph A; Tabesh, Ali

2014-02-01

An analytical representation of the leading non-Gaussian corrections for a class of diffusion orientation distribution functions (dODFs) is presented. This formula is constructed from the diffusion and diffusional kurtosis tensors, both of which may be estimated with diffusional kurtosis imaging (DKI). By incorporating model-independent non-Gaussian diffusion effects, it improves on the Gaussian approximation used in diffusion tensor imaging (DTI). This analytical representation therefore provides a natural foundation for DKI-based white matter fiber tractography, which has potential advantages over conventional DTI-based fiber tractography in generating more accurate predictions for the orientations of fiber bundles and in being able to directly resolve intra-voxel fiber crossings. The formula is illustrated with numerical simulations for a two-compartment model of fiber crossings and for human brain data. These results indicate that the inclusion of the leading non-Gaussian corrections can significantly affect fiber tractography in white matter regions, such as the centrum semiovale, where fiber crossings are common. 2013 John Wiley & Sons, Ltd.

Leading Non-Gaussian Corrections for Diffusion Orientation Distribution Function

PubMed Central

Jensen, Jens H.; Helpern, Joseph A.; Tabesh, Ali

2014-01-01

An analytical representation of the leading non-Gaussian corrections for a class of diffusion orientation distribution functions (dODFs) is presented. This formula is constructed out of the diffusion and diffusional kurtosis tensors, both of which may be estimated with diffusional kurtosis imaging (DKI). By incorporating model-independent non-Gaussian diffusion effects, it improves upon the Gaussian approximation used in diffusion tensor imaging (DTI). This analytical representation therefore provides a natural foundation for DKI-based white matter fiber tractography, which has potential advantages over conventional DTI-based fiber tractography in generating more accurate predictions for the orientations of fiber bundles and in being able to directly resolve intra-voxel fiber crossings. The formula is illustrated with numerical simulations for a two-compartment model of fiber crossings and for human brain data. These results indicate that the inclusion of the leading non-Gaussian corrections can significantly affect fiber tractography in white matter regions, such as the centrum semiovale, where fiber crossings are common. PMID:24738143

Fiber-Optic Terahertz Data-Communication Networks

NASA Technical Reports Server (NTRS)

Chua, Peter L.; Lambert, James L.; Morookian, John M.; Bergman, Larry A.

1994-01-01

Network protocols implemented in optical domain. Fiber-optic data-communication networks utilize fully available bandwidth of single-mode optical fibers. Two key features of method: use of subpicosecond laser pulses as carrier signals and spectral phase modulation of pulses for optical implementation of code-division multiple access as multiplexing network protocol. Local-area network designed according to concept offers full crossbar functionality, security of data in transit through network, and capacity about 100 times that of typical fiber-optic local-area network in current use.

The effect of alkaline treatment and fiber orientation on impact resistant of bio-composites Sansevieria trifasciata fiber/polypropylene as automotive components material

NASA Astrophysics Data System (ADS)

Shieddieque, Apang Djafar; Mardiyati, Suratman, Rochim; Widyanto, Bambang

2018-04-01

The increasing amount of car usage is causing an escalated amount of fuel consumption and CO2 emission. It implicates demand for the automotive industry to increase the efficiency of their products, One of the most effective ways to solve the issue is to find green weight light material for the interior automotive component. The Aim of this research was to investigate the effect of alkaline treatment and fiber orientation on the impact resistant of material bio- composite sansevieiria trifasciata fiber/Polypropylene. In this research, bio-composites sansevieria trifasciata fiber/Polypropylene was prepared with random fiber orientation and unidirectional orientation by using a hot press method with pressure 140 Bar and temperature 240°C. Fiber was taken from Sansevieria trifasciata by using mechanical retting. In this study, Sansevieria fiber was given alkaline treatment (mercerization) with NaOH 3% (w/w) solution at temperature 100°C for an hour. The fraction of fiber volume that were used in this experiment are 0%, 5%, 10%, and 15%. The impact test was conducted based on ASTM D 6110 - 04, and the fracture analysis was investigated by scanning electron microscope (SEM). The best result of impact toughness and fracture analysis were achieved by bio composite untreated and unidirectional sansevieria trifasciata fiber/Polypropylene with fiber volume fraction of 15%, which was 48.092kJ/m2 for impact resistant. As compared to the impact toughness standard, which needed for interior automotive component, the impact toughness of sansevieria trifasciata fiber/Polypropylene has fulfilled the standard of the interior material automotive industry. Therefore, this material can be potentially used as materials on the car exterior component.

Direct-write 3D printing of composite materials with magnetically aligned discontinuous reinforcement

NASA Astrophysics Data System (ADS)

Martin, Joshua J.; Caunter, Andrew; Dendulk, Amy; Goodrich, Scott; Pembroke, Ryan; Shores, Dan; Erb, Randall M.

2017-05-01

Three-dimensional (3D) printing of fiber reinforced composites represents an enabling technology that may bring toughness and specific strength to complex parts. Recently, direct-write 3D printing has been offered as a promising route to manufacturing fiber reinforced composites that show high specific strength. These approaches primarily rely on the use of shear-alignment during the extrusion process to align fibers along the printing direction. Shear alignment prevents fibers from being oriented along principle stress directions of the final designed part. This paper describes a new direct-write style 3D printing system that incorporates magnetic fields to actively control the orientation of reinforcing fibers during the printing of fiber reinforced composites. Such a manufacturing system is fraught with complications from the high shear dominated alignment experienced by the fibers during extrusion to the slow magnetic alignment dynamics of fibers in viscous media. Here we characterize these issues and suggest effective operating windows in which magnetic alignment is a viable approach to orienting reinforcing particles during direct-write 3D printing.

Optimization model for UDWDM-PON deployment based on physical restrictions and asymmetric user's clustering

NASA Astrophysics Data System (ADS)

Arévalo, Germán. V.; Hincapié, Roberto C.; Sierra, Javier E.

2015-09-01

UDWDM PON is a leading technology oriented to provide ultra-high bandwidth to final users while profiting the physical channels' capability. One of the main drawbacks of UDWDM technique is the fact that the nonlinear effects, like FWM, become stronger due to the close spectral proximity among channels. This work proposes a model for the optimal deployment of this type of networks taking into account the fiber length limitations imposed by physical restrictions related with the fiber's data transmission as well as the users' asymmetric distribution in a provided region. The proposed model employs the data transmission related effects in UDWDM PON as restrictions in the optimization problem and also considers the user's asymmetric clustering and the subdivision of the users region though a Voronoi geometric partition technique. Here it is considered de Voronoi dual graph, it is the Delaunay Triangulation, as the planar graph for resolving the problem related with the minimum weight of the fiber links.

Estimation of Local Orientations in Fibrous Structures With Applications to the Purkinje System

PubMed Central

Plank, Gernot; Trayanova, Natalia A.; Vidal, René

2011-01-01

The extraction of the cardiac Purkinje system (PS) from intensity images is a critical step toward the development of realistic structural models of the heart. Such models are important for uncovering the mechanisms of cardiac disease and improving its treatment and prevention. Unfortunately, the manual extraction of the PS is a challenging and error-prone task due to the presence of image noise and numerous fiber junctions. To deal with these challenges, we propose a framework that estimates local fiber orientations with high accuracy and reconstructs the fibers via tracking. Our key contribution is the development of a descriptor for estimating the orientation distribution function (ODF), a spherical function encoding the local geometry of the fibers at a point of interest. The fiber/branch orientations are identified as the modes of the ODFs via spherical clustering and guide the extraction of the fiber centerlines. Experiments on synthetic data evaluate the sensitivity of our approach to image noise, width of the fiber, and choice of the mode detection strategy, and show its superior performance compared to those of the existing descriptors. Experiments on the free-running PS in an MR image also demonstrate the accuracy of our method in reconstructing such sparse fibrous structures. PMID:21335301

Topology effects on nonaffine behavior of semiflexible fiber networks

NASA Astrophysics Data System (ADS)

Hatami-Marbini, H.; Shriyan, V.

2017-12-01

Filamentous semiflexible networks define the mechanical and physical properties of many materials such as cytoskeleton. In the absence of a distinct unit cell, the Mikado fiber network model is commonly used algorithm for representing the microstructure of these networks in numerical models. Nevertheless, certain types of filamentous structures such as collagenous tissues, at early stages of their development, are assembled by growth of individual fibers from random nucleation sites. In this work, we develop a computational model to investigate the mechanical response of such networks by characterizing their nonaffine behavior. We show that the deformation of these networks is nonaffine at all length scales. Furthermore, similar to Mikado networks, the degree of nonaffinity in these structures decreases with increasing the probing length scale, the network fiber density, and/or the bending stiffness of constituting filaments. Nevertheless, despite the lower coordination number of these networks, their deformation field is more affine than that of the Mikado networks with the same fiber density and fiber mechanical properties.

Composite Reinforcement by Magnetic Control of Fiber Density and Orientation.

PubMed

Goldberg, Omri; Greenfeld, Israel; Wagner, H Daniel

2018-05-08

The flexural rigidity of cylindrical specimens, composed of epoxy reinforced by short, magnetized glass fibers, was enhanced using weak magnetic fields (<100 mT). By spatially controlling the magnitude and direction of the field, and thereby the torques and forces acting locally on the fibers, the orientation and concentration of the fillers in the matrix could be tuned prior to curing. Unidirectional alignment of the fibers, achieved using an air-core solenoid, improved the contribution of the fibers to the flexure modulus by a factor of 3. When a ring-shaped permanent magnet was utilized, the glass fibers were migrated preferentially near the rod boundary, and as a result, the contribution of the fibers to the flexure modulus doubled. The fiber length, density, and orientation distributions were extracted by μCT image analysis, allowing comparison of the experimental flexure modulus to a modified rule of mixtures prediction. The ability to magnetically control the fiber distribution in reinforced composites demonstrated in this study may be applied in the fabrication of complex micro- and macroscale structures with spatially variable anisotropy, allowing features such as crack diversion, strengthening of highly loaded regions, as well as economic management of materials and weight.

Hyperelastic remodeling in the intrauterine growth restricted (IUGR) carotid artery in the near-term fetus

PubMed Central

Dodson, R. Blair; Rozance, Paul J.; Reina-Romo, Esther; Ferguson, Virginia L.; Hunter, Kendall S.

2013-01-01

A constitutive model for a fiber reinforced hyperelastic material was applied to understand arterial fiber remodeling in a sheep model of Intrauterine Growth Restriction (IUGR). IUGR is associated altered hemodynamics characterized by increased resistance to blood flow in the placenta and elevated fetal arterial pressure and pulsatility. The constitutive model describes the collagen contribution to the mechanics within the arterial wall in both control and IUGR carotid artery through defining the material modulus and the orientation of the microstructure. A sheep model of placental insufficiency induced IUGR (PI-IUGR) was created by exposure of the pregnant ewe to elevated ambient temperatures. Experimental data was collected using pressure–diameter measurements to measure passive compliance in control and PI-IUGR carotid arteries. The constitutive model was optimized to fit the experimental data predicting the material parameters. Specifically, the collagen fiber predicted angle (γ) in the control artery was 49.9° from the circumferential axis while the PI-IUGR was 16.6° with a 23.5% increase in fiber orientation (κ). Quantitative assessment of collagen fiber orientation in secondary harmonic generation images confirmed the shift in orientation between the two groups. Together these suggest vascular remodeling of the ECM fiber orientation plays a major role in arterial stiffening in the PI-IUGR near-term fetal sheep. PMID:23332229

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 3: Advanced networks and economics

NASA Technical Reports Server (NTRS)

1986-01-01

This study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 3: Advanced networks and economics

NASA Astrophysics Data System (ADS)

1986-10-01

This study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

Prediction of Tensile Behavior of UHSFRC Considering the Flow Field in the Placing Dominated by Shear Flow.

PubMed

Moon, Joon-Shik; Kang, Su-Tae

2018-01-26

Considering the case of fabricating a UHSFRC (ultra-high strength fiber-reinforced concrete) beam with the method of one end placing and self-flowing to the other end, it was intended to simulate the variation of the fiber orientation distribution according to the flow distance and the variation of the resultant tensile behaviors. Then the validity of the simulation approach was shown by comparing the simulated results with experimental ones. A three-point bending test with a notched beam was adopted for the experiment and a finite element analysis was performed to obtain the simulated results for the bending test considering the flow-dependent tensile behavior of the UHSFRC. From the simulation for the fiber orientation distribution according to the flow distance, it could be found that the major change in the fiber orientation distribution took place within a short flow distance and most of the fibers became nearly aligned to the flow direction. After some flow distance, there was a not-so-remarkable variation in the fiber orientation distribution that could influence the tensile behavior of the composite. For this flow region, the consistent flexural test results, regardless of flow distance, demonstrate the reliability of the simulation.

The use of image analysis in evaluation of the fibers orientation in Wood-polymer composites (WPC)

NASA Astrophysics Data System (ADS)

Bednarz, Arkadiusz; Frącz, Wiesław; Janowski, Grzegorz

2016-12-01

In this paper a novel way of a digital analysis of fibers orientation with a five-step algorithmwas presented. In the study, a molded piece with a dumbbell shape prepared from wood-polymer composite was used. The injection molding process was examined in experimental and numerical way. Based on the developed mathematical algorithm, a significant compliance of fiber orientation in different areas of the molded piece was obtained. The main aim of thisworkwas fiber orientation analysis of wood-polymer composites. An additional goal of thiswork was the comparison of the results reached in numerical analysis with results obtained from an experiment. The results of this research were important for the scientific and also from the practical point of view. In future works the prepared algorithm could be used to reach optimal parameters of the injection molding process.

Effects of Schwann cell alignment along the oriented electrospun chitosan nanofibers on nerve regeneration.

PubMed

Wang, Wei; Itoh, Soichiro; Konno, Katsumi; Kikkawa, Takeshi; Ichinose, Shizuko; Sakai, Katsuyoshi; Ohkuma, Tsuneo; Watabe, Kazuhiko

2009-12-15

We have constructed a chitosan nonwoven nanofiber mesh tube consisting of oriented fibers by the electrospinning method. The efficacy of oriented nanofibers on Schwann cell alignment and positive effect of this tube on peripheral nerve regeneration were confirmed. The physical properties of the chitosan nanofiber mesh sheets prepared by electrospinning with or without fiber orientation were characterized. Then, immortalized Schwann cells were cultured on these sheets. Furthermore, the chitosan nanofiber mesh tubes with or without orientation, and bilayered chitosan mesh tube with an inner layer of oriented nanofibers and an outer layer of randomized nanofibers were bridgegrafted into rat sciatic nerve defect. As a result of fiber orientation, the tensile strength along the axis of the sheet increased. Because Schwann cells aligned along the nanofibers, oriented fibrous sheets could exhibit a Schwann cell column. Functional recovery and electrophysiological recovery occurred in time in the oriented group as well as in the bilayered group, and approximately matched those in the isograft. Furthermore, histological analysis revealed that the sprouting of myelinated axons occurred vigorously followed by axonal maturation in the isograft, oriented, and bilayered group in the order. The oriented chitosan nanofiber mesh tube may be a promising substitute for autogenous nerve graft.

Multiple-Ring Digital Communication Network

NASA Technical Reports Server (NTRS)

Kirkham, Harold

1992-01-01

Optical-fiber digital communication network to support data-acquisition and control functions of electric-power-distribution networks. Optical-fiber links of communication network follow power-distribution routes. Since fiber crosses open power switches, communication network includes multiple interconnected loops with occasional spurs. At each intersection node is needed. Nodes of communication network include power-distribution substations and power-controlling units. In addition to serving data acquisition and control functions, each node acts as repeater, passing on messages to next node(s). Multiple-ring communication network operates on new AbNET protocol and features fiber-optic communication.

Material properties of CorCap passive cardiac support device.

PubMed

Chitsaz, Sam; Wenk, Jonathan F; Ge, Liang; Wisneski, Andrew; Mookhoek, Aart; Ratcliffe, Mark B; Guccione, Julius M; Tseng, Elaine E

2013-01-01

Myocardial function deteriorates during ventricular remodeling in patients with congestive heart failure (HF). Ventricular restraint therapy using a cardiac support device (CSD) is designed to reduce the amount of stress inside the dilated ventricles, which in turn halts remodeling. However, as an open mesh surrounding the heart, it is unknown what the mechanical properties of the CSD are in different fiber orientations. Composite specimens of CorCap (Acorn Cardiovascular, Inc, St. Paul, MN) CSD fabric and silicone were constructed in different fiber orientations and tested on a custom-built biaxial stretcher. Silicone controls were made and stretched to detect the parameters of the matrix. CSD coefficients were calculated using the composite and silicone matrix stress-strain data. Stiffness in different fiber orientations was determined. Silicone specimens exerted a linear behavior, with stiffness of 2.57 MPa. For the composites with 1 fiber set aligned with respect to the stretch axes, stiffness in the direction of the aligned fiber set was higher than that in the cross-fiber direction (14.39 MPa versus 5.66 MPa), indicating greater compliance in the cross-fiber direction. When the orientation of the fiber sets in the composite were matched to the expected clinical orientation of the implanted CorCap, the stiffness in the circumferential axis (with respect to the heart) was greater than in the longitudinal axis (10.55 MPa versus 9.70 MPa). The mechanical properties of the CorCap demonstrate directionality with greater stiffness circumferentially than longitudinally. Implantation of the CorCap clinically should take into account the directionality of the biomechanics to optimize ventricular restraint. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Inclined Fiber Pullout from a Cementitious Matrix: A Numerical Study

PubMed Central

Zhang, Hui; Yu, Rena C.

2016-01-01

It is well known that fibers improve the performance of cementitious composites by acting as bridging ligaments in cracks. Such bridging behavior is often studied through fiber pullout tests. The relation between the pullout force vs. slip end displacement is characteristic of the fiber-matrix interface. However, such a relation varies significantly with the fiber inclination angle. In the current work, we establish a numerical model to simulate the entire pullout process by explicitly representing the fiber, matrix and the interface for arbitrary fiber orientations. Cohesive elements endorsed with mixed-mode fracture capacities are implemented to represent the bond-slip behavior at the interface. Contact elements with Coulomb’s friction are placed at the interface to simulate frictional contact. The bond-slip behavior is first calibrated through pull-out curves for fibers aligned with the loading direction, then validated against experimental results for steel fibers oriented at 30∘ and 60∘. Parametric studies are then performed to explore the influences of both material properties (fiber yield strength, matrix tensile strength, interfacial bond) and geometric factors (fiber diameter, embedment length and inclination angle) on the overall pullout behavior, in particular on the maximum pullout load. The proposed methodology provides the necessary pull-out curves for a fiber oriented at a given angle for multi-scale models to study fracture in fiber-reinforced cementitious materials. The novelty lies in its capacity to capture the entire pullout process for a fiber with an arbitrary inclination angle. PMID:28773921

Inclined Fiber Pullout from a Cementitious Matrix: A Numerical Study.

PubMed

Zhang, Hui; Yu, Rena C

2016-09-26

It is well known that fibers improve the performance of cementitious composites by acting as bridging ligaments in cracks. Such bridging behavior is often studied through fiber pullout tests. The relation between the pullout force vs. slip end displacement is characteristic of the fiber-matrix interface. However, such a relation varies significantly with the fiber inclination angle. In the current work, we establish a numerical model to simulate the entire pullout process by explicitly representing the fiber, matrix and the interface for arbitrary fiber orientations. Cohesive elements endorsed with mixed-mode fracture capacities are implemented to represent the bond-slip behavior at the interface. Contact elements with Coulomb's friction are placed at the interface to simulate frictional contact. The bond-slip behavior is first calibrated through pull-out curves for fibers aligned with the loading direction, then validated against experimental results for steel fibers oriented at 30 ∘ and 60 ∘ . Parametric studies are then performed to explore the influences of both material properties (fiber yield strength, matrix tensile strength, interfacial bond) and geometric factors (fiber diameter, embedment length and inclination angle) on the overall pullout behavior, in particular on the maximum pullout load. The proposed methodology provides the necessary pull-out curves for a fiber oriented at a given angle for multi-scale models to study fracture in fiber-reinforced cementitious materials. The novelty lies in its capacity to capture the entire pullout process for a fiber with an arbitrary inclination angle.

US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1986-01-01

Over the past two decades, fiber optics has emerged as a highly practical and cost-efficient communications technology. Its competitiveness vis-a-vis other transmission media, especially satellite, has become a critical question. This report studies the likely evolution and application of fiber optic networks in the United States to the end of the century. The outlook for the technology of fiber systems is assessed and forecast, scenarios of the evolution of fiber optic network development are constructed, and costs to provide service are determined and examined parametrically as a function of network size and traffic carried. Volume 1 consists of the Executive Summary. Volume 2 focuses on fiber optic technology and long distance fiber optic networks. Volume 3 develops a traffic and financial model of a nationwide long distance transmission network. Among the study's most important conclusions are: revenue requirements per circuit for LATA-to-LATA fiber optic links are less than one cent per call minute; multiplex equipment, which is likely to be required in any competing system, is the largest contributor to circuit costs; the potential capacity of fiber optic cable is very large and as yet undefined; and fiber optic transmission combined with other network optimization schemes can lead to even lower costs than those identified in this study.

Self-Assembly of Hierarchical DNA Nanotube Architectures with Well-Defined Geometries.

PubMed

Jorgenson, Tyler D; Mohammed, Abdul M; Agrawal, Deepak K; Schulman, Rebecca

2017-02-28

An essential motif for the assembly of biological materials such as actin at the scale of hundreds of nanometers and beyond is a network of one-dimensional fibers with well-defined geometry. Here, we demonstrate the programmed organization of DNA filaments into micron-scale architectures where component filaments are oriented at preprogrammed angles. We assemble L-, T-, and Y-shaped DNA origami junctions that nucleate two or three micron length DNA nanotubes at high yields. The angles between the nanotubes mirror the angles between the templates on the junctions, demonstrating that nanoscale structures can control precisely how micron-scale architectures form. The ability to precisely program filament orientation could allow the assembly of complex filament architectures in two and three dimensions, including circuit structures, bundles, and extended materials.

Coupling analysis of non-circular-symmetric modes and design of orientation-insensitive few-mode fiber couplers

NASA Astrophysics Data System (ADS)

Li, Jiaxiong; Du, Jiangbing; Ma, Lin; Li, Ming-Jun; Jiang, Shoulin; Xu, Xiao; He, Zuyuan

2017-01-01

We study the coupling between two identical weakly-coupled few-mode fibers based on coupled-mode theory. The coupling behavior of non-circular-symmetric modes, such as LP11 and LP21, is investigated analytically and numerically. By carefully choosing the fiber core separation and coupler length, we can design orientation-insensitive fiber couplers for non-circular-symmetric modes at arbitrary coupling ratios. Based on the design method, we propose an orientation-insensitive two-mode fiber coupler at 850 nm working as a mode multiplexer/demultiplexer for two-mode transmission using standard single-mode fiber. Within the band from 845 to 855 nm, the insertion losses of LP01 and LP11 modes are less than 0.03 dB and 0.24 dB, respectively. When the two-mode fiber coupler is used as mode demultiplexer, the LP01/LP11 and LP11/LP01 extinction ratios in the separated branches are respectively above 12.6 dB and 21.2 dB. Our design method can be extended to two-mode communication or sensing systems at other wavelengths.

Flexible Composite-Material Pressure Vessel

NASA Technical Reports Server (NTRS)

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

X-ray Studies of Regenerated Cellulose Fibers Wet Spun from Cotton Linter Pulp in NaOH/Thiourea Aqueous Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen,X.; Burger, C.; Fang, D.

Regenerated cellulose fibers were fabricated by dissolution of cotton linter pulp in NaOH (9.5 wt%) and thiourea (4.5 wt%) aqueous solution followed by wet-spinning and multi-roller drawing. The multi-roller drawing process involved three stages: coagulation (I), coagulation (II) and post-treatment (III). The crystalline structure and morphology of regenerated cellulose fiber was investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. Results indicated that only the cellulose II crystal structure was found in regenerated cellulose fibers, proving that the cellulose crystals were completely transformed from cellulose I to II structure during spinning from NaOH/thiourea aqueous solution. Themore » crystallinity, orientation and crystal size at each stage were determined from the WAXD analysis. Drawing of cellulose fibers in the coagulation (II) bath (H{sub 2}SO{sub 4}/H{sub 2}O) was found to generate higher orientation and crystallinity than drawing in the post-treatment (III). Although the post-treatment process also increased crystal orientation, it led to a decrease in crystallinity with notable reduction in the anisotropic fraction. Compared with commercial rayon fibers fabricated by the viscose process, the regenerated cellulose fibers exhibited higher crystallinity but lower crystal orientation. SAXS results revealed a clear scattering maximum along the meridian direction in all regenerated cellulose fibers, indicating the formation of lamellar structure during spinning.« less

Neighborhood resolved fiber orientation distributions (NRFOD) in automatic labeling of white matter fiber pathways.

PubMed

Ugurlu, Devran; Firat, Zeynep; Türe, Uğur; Unal, Gozde

2018-05-01

Accurate digital representation of major white matter bundles in the brain is an important goal in neuroscience image computing since the representations can be used for surgical planning, intra-patient longitudinal analysis and inter-subject population connectivity studies. Reconstructing desired fiber bundles generally involves manual selection of regions of interest by an expert, which is subject to user bias and fatigue, hence an automation is desirable. To that end, we first present a novel anatomical representation based on Neighborhood Resolved Fiber Orientation Distributions (NRFOD) along the fibers. The resolved fiber orientations are obtained by generalized q-sampling imaging (GQI) and a subsequent diffusion decomposition method. A fiber-to-fiber distance measure between the proposed fiber representations is then used in a density-based clustering framework to select the clusters corresponding to the major pathways of interest. In addition, neuroanatomical priors are utilized to constrain the set of candidate fibers before density-based clustering. The proposed fiber clustering approach is exemplified on automation of the reconstruction of the major fiber pathways in the brainstem: corticospinal tract (CST); medial lemniscus (ML); middle cerebellar peduncle (MCP); inferior cerebellar peduncle (ICP); superior cerebellar peduncle (SCP). Experimental results on Human Connectome Project (HCP)'s publicly available "WU-Minn 500 Subjects + MEG2 dataset" and expert evaluations demonstrate the potential of the proposed fiber clustering method in brainstem white matter structure analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

Architectures of fiber optic network in telecommunications

NASA Astrophysics Data System (ADS)

Vasile, Irina B.; Vasile, Alexandru; Filip, Luminita E.

2005-08-01

The operators of telecommunications have targeted their efforts towards realizing applications using broad band fiber optics systems in the access network. Thus, a new concept related to the implementation of fiber optic transmission systems, named FITL (Fiber In The Loop) has appeared. The fiber optic transmission systems have been extensively used for realizing the transport and intercommunication of the public telecommunication network, as well as for assuring the access to the telecommunication systems of the great corporations. Still, the segment of the residential users and small corporations did not benefit on large scale of this technology implementation. For the purpose of defining fiber optic applications, more types of architectures were conceived, like: bus, ring, star, tree. In the case of tree-like networks passive splitters (that"s where the name of PON comes from - Passive Optical Network-), which reduce significantly the costs of the fiber optic access, by separating the costs of the optical electronic components. That's why the passive fiber optics architectures (PON represent a viable solution for realizing the access at the user's loop. The main types of fiber optics architectures included in this work are: FTTC (Fiber To The Curb); FTTB (Fiber To The Building); FTTH (Fiber To The Home).

Kernel Regression Estimation of Fiber Orientation Mixtures in Diffusion MRI

PubMed Central

Cabeen, Ryan P.; Bastin, Mark E.; Laidlaw, David H.

2016-01-01

We present and evaluate a method for kernel regression estimation of fiber orientations and associated volume fractions for diffusion MR tractography and population-based atlas construction in clinical imaging studies of brain white matter. This is a model-based image processing technique in which representative fiber models are estimated from collections of component fiber models in model-valued image data. This extends prior work in nonparametric image processing and multi-compartment processing to provide computational tools for image interpolation, smoothing, and fusion with fiber orientation mixtures. In contrast to related work on multi-compartment processing, this approach is based on directional measures of divergence and includes data-adaptive extensions for model selection and bilateral filtering. This is useful for reconstructing complex anatomical features in clinical datasets analyzed with the ball-and-sticks model, and our framework’s data-adaptive extensions are potentially useful for general multi-compartment image processing. We experimentally evaluate our approach with both synthetic data from computational phantoms and in vivo clinical data from human subjects. With synthetic data experiments, we evaluate performance based on errors in fiber orientation, volume fraction, compartment count, and tractography-based connectivity. With in vivo data experiments, we first show improved scan-rescan reproducibility and reliability of quantitative fiber bundle metrics, including mean length, volume, streamline count, and mean volume fraction. We then demonstrate the creation of a multi-fiber tractography atlas from a population of 80 human subjects. In comparison to single tensor atlasing, our multi-fiber atlas shows more complete features of known fiber bundles and includes reconstructions of the lateral projections of the corpus callosum and complex fronto-parietal connections of the superior longitudinal fasciculus I, II, and III. PMID:26691524

Supramolecular order following binding of the dichroic birefringent sulfonic dye Ponceau SS to collagen fibers.

PubMed

Vidal, B C; Mello, M L S

2005-06-15

The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggregates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fibers were investigated in order to assess their polarizing properties and similarity to liquid crystals. In some experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggregates of the dye had a negative LD, and their electronic transitions were oriented perpendicular to the filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LD signal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis of the rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picric acid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in the optical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicating that Ponceau SS was able to distinguish between different ordered states of macromolecular aggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye molecules such as Ponceau SS, collagen also formed structures with a much higher degree of orientation. The presence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this complex can act as a polarizer. Copyright 2005 Wiley Periodicals, Inc.

Three-dimensional matrix fiber alignment modulates cell migration and MT1-MMP utility by spatially and temporally directing protrusions

NASA Astrophysics Data System (ADS)

Fraley, Stephanie I.; Wu, Pei-Hsun; He, Lijuan; Feng, Yunfeng; Krisnamurthy, Ranjini; Longmore, Gregory D.; Wirtz, Denis

2015-10-01

Multiple attributes of the three-dimensional (3D) extracellular matrix (ECM) have been independently implicated as regulators of cell motility, including pore size, crosslink density, structural organization, and stiffness. However, these parameters cannot be independently varied within a complex 3D ECM protein network. We present an integrated, quantitative study of these parameters across a broad range of complex matrix configurations using self-assembling 3D collagen and show how each parameter relates to the others and to cell motility. Increasing collagen density resulted in a decrease and then an increase in both pore size and fiber alignment, which both correlated significantly with cell motility but not bulk matrix stiffness within the range tested. However, using the crosslinking enzyme Transglutaminase II to alter microstructure independently of density revealed that motility is most significantly predicted by fiber alignment. Cellular protrusion rate, protrusion orientation, speed of migration, and invasion distance showed coupled biphasic responses to increasing collagen density not predicted by 2D models or by stiffness, but instead by fiber alignment. The requirement of matrix metalloproteinase (MMP) activity was also observed to depend on microstructure, and a threshold of MMP utility was identified. Our results suggest that fiber topography guides protrusions and thereby MMP activity and motility.

Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) electrospun blend fiber scaffolds: Preparation, characterization and cytocompatibility.

PubMed

Zhijiang, Cai; Qin, Zhang; Xianyou, Song; Yuanpei, Liu

2017-02-01

In the present work, a series of Zein/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend fiber scaffolds have been prepared by electrospinning method. The electrospun fibers showed a circular and uniform morphology with random distribution. The blend fiber scaffolds possessed well interconnected porous fibrous network structure with high porosity and large aspect surface areas. The FTIR and XPS spectra of Zein/P(3HB-co-4HB) blend fibers demonstrated the same characteristics to that of pure Zein and P(3HB-co-4HB) electrospun fibers. However, Zein might hinder the crystallization of P(3HB-co-4HB) owing to the formation of weak intermolecular interactions, which can affect the preferential orientation of P(3HB-co-4HB) molecules. Only one glass transition temperature (Tg) can be detected for electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds implying the miscibility of Zein and P(3HB-co-4HB) in the blend fibers. The Zein/P(3HB-co-4HB) blend fiber scaffolds showed about 50% of improvement in tensile strength and 400% of increase in elongation at break by increasing P(3HB-co-4HB) content from 20% to 80%. The cytocompatibility of the Zein/P(3HB-co-4HB) blend fiber scaffolds was preliminarily evaluated by cell culture in vitro. The as-prepared electrospun Zein/P(3HB-co-4HB) blend fiber scaffolds with the characteristics of good biocompatibility, excellent pore characteristic as well as sufficient mechanical properties should be more promising for applications as tissue engineering scaffold. Copyright © 2016 Elsevier B.V. All rights reserved.

Fibre Optic Connections And Method For Using Same

DOEpatents

Chan, Benson; Cohen, Mitchell S.; Fortier, Paul F.; Freitag, Ladd W.; Hall, Richard R.; Johnson, Glen W.; Lin, How Tzu; Sherman, John H.

2004-03-30

A package is described that couples a twelve channel wide fiber optic cable to a twelve channel Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and a multiple channel Perpendicularly Aligned Integrated Die (PAID) receiver. The package allows for reduction in the height of the assembly package by vertically orienting certain dies parallel to the fiber optic cable and horizontally orienting certain other dies. The assembly allows the vertically oriented optoelectronic dies to be perpendicularly attached to the horizontally oriented laminate via a flexible circuit.

Crossing Fibers Detection with an Analytical High Order Tensor Decomposition

PubMed Central

Megherbi, T.; Kachouane, M.; Oulebsir-Boumghar, F.; Deriche, R.

2014-01-01

Diffusion magnetic resonance imaging (dMRI) is the only technique to probe in vivo and noninvasively the fiber structure of human brain white matter. Detecting the crossing of neuronal fibers remains an exciting challenge with an important impact in tractography. In this work, we tackle this challenging problem and propose an original and efficient technique to extract all crossing fibers from diffusion signals. To this end, we start by estimating, from the dMRI signal, the so-called Cartesian tensor fiber orientation distribution (CT-FOD) function, whose maxima correspond exactly to the orientations of the fibers. The fourth order symmetric positive definite tensor that represents the CT-FOD is then analytically decomposed via the application of a new theoretical approach and this decomposition is used to accurately extract all the fibers orientations. Our proposed high order tensor decomposition based approach is minimal and allows recovering the whole crossing fibers without any a priori information on the total number of fibers. Various experiments performed on noisy synthetic data, on phantom diffusion, data and on human brain data validate our approach and clearly demonstrate that it is efficient, robust to noise and performs favorably in terms of angular resolution and accuracy when compared to some classical and state-of-the-art approaches. PMID:25246940

Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter

NASA Astrophysics Data System (ADS)

Ghafaryasl, Babak; Baart, Robert; de Boer, Johannes F.; Vermeer, Koenraad A.; van Vliet, Lucas J.

2017-02-01

Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. A better understanding of retinal nerve fiber bundle (RNFB) trajectories in combination with visual field data may be used for future diagnosis and monitoring of glaucoma. However, manual tracing of these bundles is a tedious task. In this work, we present an automatic technique to estimate the orientation of RNFBs from volumetric OCT scans. Our method consists of several steps, starting from automatic segmentation of the RNFL. Then, a stack of en face images around the posterior nerve fiber layer interface was extracted. The image showing the best visibility of RNFB trajectories was selected for further processing. After denoising the selected en face image, a semblance structure-oriented filter was applied to probe the strength of local linear structure in a discrete set of orientations creating an orientation space. Gaussian filtering along the orientation axis in this space is used to find the dominant orientation. Next, a confidence map was created to supplement the estimated orientation. This confidence map was used as pixel weight in normalized convolution to regularize the semblance filter response after which a new orientation estimate can be obtained. Finally, after several iterations an orientation field corresponding to the strongest local orientation was obtained. The RNFB orientations of six macular scans from three subjects were estimated. For all scans, visual inspection shows a good agreement between the estimated orientation fields and the RNFB trajectories in the en face images. Additionally, a good correlation between the orientation fields of two scans of the same subject was observed. Our method was also applied to a larger field of view around the macula. Manual tracing of the RNFB trajectories shows a good agreement with the automatically obtained streamlines obtained by fiber tracking.

Radiant energy during infrared neural stimulation at the target structure

NASA Astrophysics Data System (ADS)

Richter, Claus-Peter; Rajguru, Suhrud; Stafford, Ryan; Stock, Stuart R.

2013-03-01

Infrared neural stimulation (INS) describes a method, by which an infrared laser is used to stimulate neurons. The major benefit of INS over stimulating neurons with electrical current is its spatial selectivity. To translate the technique into a clinical application it is important to know the energy required to stimulate the neural structure. With this study we provide measurements of the radiant exposure, at the target structure that is required to stimulate the auditory neurons. Flat polished fibers were inserted into scala tympani so that the spiral ganglion was in front of the optical fiber. Angle polished fibers were inserted along scala tympani, and rotating the beveled surface of the fiber allowed the radiation beam to be directed perpendicular to the spiral ganglion. The radiant exposure for stimulation at the modiolus for flat and angle polished fibers averaged 6.78+/-2.15 mJ/cm2. With the angle polished fibers, a 90º change in the orientation of the optical beam from an orientation that resulted in an INS-evoked maximum response, resulted in a 50% drop in the response amplitude. When the orientation of the beam was changed by 180º, such that it was directed opposite to the orientation with the maxima, minimum response amplitude was observed.

Investigating the relationship between changes in collagen fiber orientation during skin aging and collagen/water interactions by polarized-FTIR microimaging.

PubMed

Eklouh-Molinier, Christophe; Happillon, Teddy; Bouland, Nicole; Fichel, Caroline; Diébold, Marie-Danièle; Angiboust, Jean-François; Manfait, Michel; Brassart-Pasco, Sylvie; Piot, Olivier

2015-09-21

Upon chronological aging, human skin undergoes structural and molecular modifications, especially at the level of type I collagen. This macromolecule is one of the main dermal structural proteins and presents several age-related alterations. It exhibits a triple helical structure and assembles itself to form fibrils and fibers. In addition, water plays an important role in stabilizing the collagen triple helix by forming hydrogen-bonds between collagen residues. However, the influence of water on changes of dermal collagen fiber orientation with age has not been yet understood. Polarized-Fourier Transform Infrared (P-FTIR) imaging is an interesting biophotonic approach to determine in situ the orientation of type I collagen fibers, as we have recently shown by comparing skin samples of different ages. In this work, P-FTIR spectral imaging was performed on skin samples from two age groups (35- and 38-year-old on the one hand, 60- and 66-year-old on the other hand), and our analyses were focused on the effect of H2O/D2O substitution. Spectral data were processed with fuzzy C-means (FCM) clustering in order to distinguish different orientations of collagen fibers. We demonstrated that the orientation was altered with aging, and that D2O treatment, affecting primarily highly bound water molecules, is more marked for the youngest skin samples. Collagen-bound water-related spectral markers were also highlighted. Our results suggest a weakening of water/collagen interactions with age. This non-destructive and label-free methodology allows us to understand better the importance of bound water in collagen fiber orientation alterations occurring with skin aging. Obtaining such structural information could find benefits in dermatology as well as in cosmetics.

Three-dimensional smoothed particle hydrodynamics simulation for injection molding flow of short fiber-reinforced polymer composites

NASA Astrophysics Data System (ADS)

He, Liping; Lu, Gang; Chen, Dachuan; Li, Wenjun; Lu, Chunsheng

2017-07-01

This paper investigates the three-dimensional (3D) injection molding flow of short fiber-reinforced polymer composites using a smoothed particle hydrodynamics (SPH) simulation method. The polymer melt was modeled as a power law fluid and the fibers were considered as rigid cylindrical bodies. The filling details and fiber orientation in the injection-molding process were studied. The results indicated that the SPH method could effectively predict the order of filling, fiber accumulation, and heterogeneous distribution of fibers. The SPH simulation also showed that fibers were mainly aligned to the flow direction in the skin layer and inclined to the flow direction in the core layer. Additionally, the fiber-orientation state in the simulation was quantitatively analyzed and found to be consistent with the results calculated by conventional tensor methods.

Source polarization effects in an optical fiber fluorosensor

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1992-01-01

The exact field solution of a step-index profile fiber was used to determine the injection efficiency of a thin-film distribution of polarized sources located in the cladding of an optical fiber. Previous results for random source orientation were confirmed. The behavior of the power efficiency, P(eff), of a polarized distribution of sources was found to be similar to the behavior of a fiber with sources with random orientation. However, for sources polarized in either the x or y direction, P(eff) was found to be more efficient.

Assessing the Increase in Specific Surface Area for Electrospun Fibrous Network due to Pore Induction.

PubMed

Katsogiannis, Konstantinos Alexandros G; Vladisavljević, Goran T; Georgiadou, Stella; Rahmani, Ramin

2016-10-26

The effect of pore induction on increasing electrospun fibrous network specific surface area was investigated in this study. Theoretical models based on the available surface area of the fibrous network and exclusion of the surface area lost due to fiber-to-fiber contacts were developed. The models for calculation of the excluded area are based on Hertzian, Derjaguin-Muller-Toporov (DMT), and Johnson-Kendall-Roberts (JKR) contact models. Overall, the theoretical models correlated the network specific surface area to the material properties including density, surface tension, Young's modulus, Poisson's ratio, as well as network physical properties, such as density and geometrical characteristics including fiber radius, fiber aspect ratio and network thickness. Pore induction proved to increase the network specific surface area up to 52%, compared to the maximum surface area that could be achieved by nonporous fiber network with the same physical properties and geometrical characteristics. The model based on Johnson-Kendall-Roberts contact model describes accurately the fiber-to-fiber contact area under the experimental conditions used for pore generation. The experimental results and the theoretical model based on Johnson-Kendall-Roberts contact model show that the increase in network surface area due to pore induction can reach to up to 58%.

Practical Aspects of Access Network Indoor Extensions Using Multimode Glass and Plastic Optical Fibers

NASA Astrophysics Data System (ADS)

Keiser, Gerd; Liu, Hao-Yu; Lu, Shao-Hsi; Devi Pukhrambam, Puspa

2012-07-01

Low-cost multimode glass and plastic optical fibers are attractive for high-capacity indoor telecom networks. Many existing buildings already have glass multimode fibers installed for local area network applications. Future indoor applications will use combinations of glass multimode fibers with plastic optical fibers that have low losses in the 850-nm-1,310-nm range. This article examines real-world link losses when randomly interconnecting glass and plastic fiber segments having factory-installed connectors. Potential interconnection issues include large variations in connector losses among randomly selected fiber segments, asymmetric link losses in bidirectional links, and variations in bandwidths among different types of fibers.

Quantitative analysis of biological tissues using Fourier transform-second-harmonic generation imaging

NASA Astrophysics Data System (ADS)

Ambekar Ramachandra Rao, Raghu; Mehta, Monal R.; Toussaint, Kimani C., Jr.

2010-02-01

We demonstrate the use of Fourier transform-second-harmonic generation (FT-SHG) imaging of collagen fibers as a means of performing quantitative analysis of obtained images of selected spatial regions in porcine trachea, ear, and cornea. Two quantitative markers, preferred orientation and maximum spatial frequency are proposed for differentiating structural information between various spatial regions of interest in the specimens. The ear shows consistent maximum spatial frequency and orientation as also observed in its real-space image. However, there are observable changes in the orientation and minimum feature size of fibers in the trachea indicating a more random organization. Finally, the analysis is applied to a 3D image stack of the cornea. It is shown that the standard deviation of the orientation is sensitive to the randomness in fiber orientation. Regions with variations in the maximum spatial frequency, but with relatively constant orientation, suggest that maximum spatial frequency is useful as an independent quantitative marker. We emphasize that FT-SHG is a simple, yet powerful, tool for extracting information from images that is not obvious in real space. This technique can be used as a quantitative biomarker to assess the structure of collagen fibers that may change due to damage from disease or physical injury.

Fabrication of highly oriented nanoporous fibers via airflow bubble-spinning

NASA Astrophysics Data System (ADS)

Liu, Fujuan; Li, Shaokai; Fang, Yue; Zheng, Fangfang; Li, Junhua; He, Jihuan

2017-11-01

Highly oriented Poly(lactic acid) (PLA) nanofibers with nanoporous structures has been successfully fabricated via airflow bubble-spinning without electrostatic hazard. In this work, the volatile solvent was necessary for preparing the nanoporous fiber, which was attributed to the competition between phase separation and solvent evaporation. The interconnected porous structures were affected by the processing variables of solution concentration, airflow temperature, collecting distance and relative humidity (RH). Besides, the rheological properties of solutions were studied and the highly oriented PLA nanofibers with nanoporous structure were also completely characterized using scanning electron microscope (SEM). This study provided a novel technique that successfully gets rid of the potential safety hazards caused by unexpected static to prepare highly oriented nanoporous fibers, which would demonstrate an impressive prospect for the fields of adsorption and filtration.

Wave propagation modeling in composites reinforced by randomly oriented fibers

NASA Astrophysics Data System (ADS)

Kudela, Pawel; Radzienski, Maciej; Ostachowicz, Wieslaw

2018-02-01

A new method for prediction of elastic constants in randomly oriented fiber composites is proposed. It is based on mechanics of composites, the rule of mixtures and total mass balance tailored to the spectral element mesh composed of 3D brick elements. Selected elastic properties predicted by the proposed method are compared with values obtained by another theoretical method. The proposed method is applied for simulation of Lamb waves in glass-epoxy composite plate reinforced by randomly oriented fibers. Full wavefield measurements conducted by the scanning laser Doppler vibrometer are in good agreement with simulations performed by using the time domain spectral element method.

The Axial Compressive Strength of High Performance Polymer Fibers

DTIC Science & Technology

1985-03-01

consists of axially oriented graphitic microfibrils that have the strong and stiff graphite crystal basal plane oriented parallel to the long axis of the... microfibrils [3,4]. The synthetic rigid polymer fibers are represented by only one commercial material: the PPTA fibers produced by E.I. DuPont de...and/or microfibrils is presented. A potential energy balance analysis is used to calculate critical stresses for the onset of compressive buckling

Comparison of cell behavior on pva/pva-gelatin electrospun nanofibers with random and aligned configuration

NASA Astrophysics Data System (ADS)

Huang, Chen-Yu; Hu, Keng-Hsiang; Wei, Zung-Hang

2016-12-01

Electrospinning technique is able to create nanofibers with specific orientation. Poly(vinyl alcohol) (PVA) have good mechanical stability but poor cell adhesion property due to the low affinity of protein. In this paper, extracellular matrix, gelatin is incorporated into PVA solution to form electrospun PVA-gelatin nanofibers membrane. Both randomly oriented and aligned nanofibers are used to investigate the topography-induced behavior of fibroblasts. Surface morphology of the fibers is studied by optical microscopy and scanning electron microscopy (SEM) coupled with image analysis. Functional group composition in PVA or PVA-gelatin is investigated by Fourier Transform Infrared (FTIR). The morphological changes, surface coverage, viability and proliferation of fibroblasts influenced by PVA and PVA-gelatin nanofibers with randomly orientated or aligned configuration are systematically compared. Fibroblasts growing on PVA-gelatin fibers show significantly larger projected areas as compared with those cultivated on PVA fibers which p-value is smaller than 0.005. Cells on PVA-gelatin aligned fibers stretch out extensively and their intracellular stress fiber pull nucleus to deform. Results suggest that instead of the anisotropic topology within the scaffold trigger the preferential orientation of cells, the adhesion of cell membrane to gelatin have substantial influence on cellular behavior.

Mechanical remodeling of normally sized mammalian cells under a gravity vector.

PubMed

Zhang, Chen; Zhou, Lüwen; Zhang, Fan; Lü, Dongyuan; Li, Ning; Zheng, Lu; Xu, Yanhong; Li, Zhan; Sun, Shujin; Long, Mian

2017-02-01

Translocation of the dense nucleus along a gravity vector initiates mechanical remodeling of a cell, but the underlying mechanisms of cytoskeletal network and focal adhesion complex (FAC) reorganization in a mammalian cell remain unclear. We quantified the remodeling of an MC3T3-E1 cell placed in upward-, downward-, or edge-on-orientated substrate. Nucleus longitudinal translocation presents a high value in downward orientation at 24 h or in edge-on orientation at 72 h, which is consistent with orientation-dependent distribution of perinuclear actin stress fibers and vimentin cords. Redistribution of total FAC area and fractionized super mature adhesion number coordinates this dependence at short duration. This orientation-dependent remodeling is associated with nucleus flattering and lamin A/C phosphorylation. Actin depolymerization or Rho-associated protein kinase signaling inhibition abolishes the orientation dependence of nucleus translocation, whereas tubulin polymerization inhibition or vimentin disruption reserves the dependence. A biomechanical model is therefore proposed for integrating the mechanosensing of nucleus translocation with cytoskeletal remodeling and FAC reorganization induced by a gravity vector.-Zhang, C., Zhou, L., Zhang, F., Lü, D., Li, N., Zheng, L., Xu, Y., Li, Z., Sun, S., Long, M. Mechanical remodeling of normally sized mammalian cells under a gravity vector. © FASEB.

Influence of intramuscular fiber orientation on the Achilles tendon curvature using three-dimensional finite element modeling of contracting skeletal muscle.

PubMed

Kinugasa, Ryuta; Yamamura, Naoto; Sinha, Shantanu; Takagi, Shu

2016-10-03

Tendon curvature plays a key role in mechanical gain (amplifying the joint excursion relative to fiber length change) during joint motion, but the mechanism remains unresolved. A three-dimensional finite element (FE) model was used to investigate the influence of intramuscular fiber orientation upon the curvature pattern of the Achilles tendon during active muscular contraction. Two simulation models, with fiber pennation angles of θ = 25° and 47° were tested for the gastrocnemius and soleus muscles. A smaller pennation angle (25°) of the soleus muscle fibers was accompanied by a large change in curvature whereas a larger pennation angle (47°) of the soleus muscle was accompanied by small effects. These results suggest that the fiber pennation angle determines the curvature of the tendon, and the magnitude of the curvature varies along the length of the aponeurosis. Such FE modeling has the potential of determining changes in force output consequent to changes in intramuscular fiber orientation arising from resistance training or unloading, and provides mechanism for predicting the risk of Achilles tendon ruptures. Copyright © 2016 Elsevier Ltd. All rights reserved.

In-plane orientation and composition dependences of crystal structure and electrical properties of {100}-oriented Pb(Zr,Ti)O3 films grown on (100) Si substrates by metal organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Okamoto, Shoji; Sankara Rama Krishnan, P. S.; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

2017-10-01

In-plane orientation-controlled Pb(Zr x ,Ti1- x )O3 (PZT) films with a thickness of approximately 2 µm and a Zr/(Zr + Ti) ratio of 0.39-0.65 were grown on (100) Si substrates by pulsed metal-organic chemical vapor deposition (MOCVD). In-plane-oriented epitaxial PZT films and in-plane random fiber-textured PZT films with {100} out-of-plane orientation were grown on (100)c SrRuO3//(100)c LaNiO3//(100) CeO2//(100) YSZ//(100) Si and (100)c SrRuO3/(100)c LaNiO3/(111) Pt/TiO2/SiO2/(100) Si substrates, respectively. The effects of Zr/(Zr + Ti) ratio and in-plane orientation on the crystal structure, dielectric, ferroelectric, and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that the epitaxial PZT films had a higher volume fraction of (100) orientation than the fiber-textured PZT films in the tetragonal Zr/(Zr + Ti) ratio region. A large difference was not detected between the epitaxial films and the fiber-textured films for Zr/(Zr + Ti) ratio dependence of the dielectric constant, and remanent polarization. However, in the rhombohedral phase region [Zr/(Zr + Ti) = 0.65], coercive field was found to be 1.5-fold different between the epitaxial and fiber-textured PZT films. The maximum field-induced strains measured at 0-100 kV/cm by scanning atomic force microscopy were obtained at approximately Zr/(Zr + Ti) = 0.50 and were about 0.5 and 0.3% for the epitaxial and fiber-textured PZT films, respectively.

Bifunctional Rhodamine Probes of Myosin Regulatory Light Chain Orientation in Relaxed Skeletal Muscle Fibers

PubMed Central

Brack, Andrew S.; Brandmeier, Birgit D.; Ferguson, Roisean E.; Criddle, Susan; Dale, Robert E.; Irving, Malcolm

2004-01-01

The orientation of the regulatory light chain (RLC) region of the myosin heads in relaxed skinned fibers from rabbit psoas muscle was investigated by polarized fluorescence from bifunctional rhodamine (BR) probes cross-linking pairs of cysteine residues introduced into the RLC. Pure 1:1 BR-RLC complexes were exchanged into single muscle fibers in EDTA rigor solution for 30 min at 30°C; ∼60% of the native RLC was removed and stoichiometrically replaced by BR-RLC, and >85% of the BR-RLC was located in the sarcomeric A-bands. The second- and fourth-rank order parameters of the orientation distributions of BR dipoles linking RLC cysteine pairs 100-108, 100-113, 108-113, and 104-115 were calculated from polarized fluorescence intensities, and used to determine the smoothest RLC orientation distribution—the maximum entropy distribution—consistent with the polarized fluorescence data. Maximum entropy distributions in relaxed muscle were relatively broad. At the peak of the distribution, the “lever” axis, linking Cys707 and Lys843 of the myosin heavy chain, was at 70–80° to the fiber axis, and the “hook” helix (Pro830–Lys843) was almost coplanar with the fiber and lever axes. The temperature and ionic strength of the relaxing solution had small but reproducible effects on the orientation of the RLC region. PMID:15041671

Analysis of key factors influencing the evaporation performances of an oriented linear cutting copper fiber sintered felt

NASA Astrophysics Data System (ADS)

Pan, Minqiang; Zhong, Yujian

2018-01-01

Porous structure can effectively enhance the heat transfer efficiency. A kind of micro vaporizer using the oriented linear cutting copper fiber sintered felt is proposed in this work. Multiple long cutting copper fibers are firstly fabricated with a multi-tooth tool and then sintered together in parallel to form uniform thickness metal fiber sintered felts that provided a characteristic of oriented microchannels. The temperature rise response and thermal conversion efficiency are experimentally investigated to evaluate the influences of porosity, surface structure, feed flow rate and input power on the evaporation characteristics. It is indicated that the temperature rise response of water is mainly affected by input power and feed flow rate. High input power and low feed flow rate present better temperature rise response of water. Porosity rather than surface structure plays an important role in the temperature rise response of water at a relatively high input power. The thermal conversion efficiency is dominated by the input power and surface structure. The oriented linear cutting copper fiber sintered felts for three kinds of porosities show better thermal conversion efficiency than that of the oriented linear copper wire sintered felt when the input power is less than 115 W. All the sintered felts have almost the same performance of thermal conversion at a high input power.

Cotton genotypes selection through artificial neural networks.

PubMed

Júnior, E G Silva; Cardoso, D B O; Reis, M C; Nascimento, A F O; Bortolin, D I; Martins, M R; Sousa, L B

2017-09-27

Breeding programs currently use statistical analysis to assist in the identification of superior genotypes at various stages of a cultivar's development. Differently from these analyses, the computational intelligence approach has been little explored in genetic improvement of cotton. Thus, this study was carried out with the objective of presenting the use of artificial neural networks as auxiliary tools in the improvement of the cotton to improve fiber quality. To demonstrate the applicability of this approach, this research was carried out using the evaluation data of 40 genotypes. In order to classify the genotypes for fiber quality, the artificial neural networks were trained with replicate data of 20 genotypes of cotton evaluated in the harvests of 2013/14 and 2014/15, regarding fiber length, uniformity of length, fiber strength, micronaire index, elongation, short fiber index, maturity index, reflectance degree, and fiber quality index. This quality index was estimated by means of a weighted average on the determined score (1 to 5) of each characteristic of the HVI evaluated, according to its industry standards. The artificial neural networks presented a high capacity of correct classification of the 20 selected genotypes based on the fiber quality index, so that when using fiber length associated with the short fiber index, fiber maturation, and micronaire index, the artificial neural networks presented better results than using only fiber length and previous associations. It was also observed that to submit data of means of new genotypes to the neural networks trained with data of repetition, provides better results of classification of the genotypes. When observing the results obtained in the present study, it was verified that the artificial neural networks present great potential to be used in the different stages of a genetic improvement program of the cotton, aiming at the improvement of the fiber quality of the future cultivars.

Topological Edge Floppy Modes in Disordered Fiber Networks

NASA Astrophysics Data System (ADS)

Zhou, Di; Zhang, Leyou; Mao, Xiaoming

2018-02-01

Disordered fiber networks are ubiquitous in a broad range of natural (e.g., cytoskeleton) and manmade (e.g., aerogels) materials. In this Letter, we discuss the emergence of topological floppy edge modes in two-dimensional fiber networks as a result of deformation or active driving. It is known that a network of straight fibers exhibits bulk floppy modes which only bend the fibers without stretching them. We find that, interestingly, with a perturbation in geometry, these bulk modes evolve into edge modes. We introduce a topological index for these edge modes and discuss their implications in biology.

Techno-Economic Analysis of FiWi Access Networks Based on 802.11ac WLAN and NG-PON2 Networks

NASA Astrophysics Data System (ADS)

Breskovic, Damir; Begusic, Dinko

2017-05-01

In this article, techno-economic analysis of a fiber-wireless access network is presented. With high bandwidth capacity of the gigabit passive optical network and with cost-effectiveness of very high throughput 802.11ac wireless local area networks that enable user mobility in the wireless segment, fiber-wireless access networks can be considered as an alternative to the fiber-to-the-home architecture for next generation access networks. Analysis based on the proposed scenario here, shows that a fiber-wireless access network is a more cost-effective solution in densely populated areas, but with some introduced improvements, even other geotypes can be considered as a commercially-viable solution.

Motion-artifact-robust, polarization-resolved second-harmonic-generation microscopy based on rapid polarization switching with electro-optic Pockells cell and its application to in vivo visualization of collagen fiber orientation in human facial skin

PubMed Central

Tanaka, Yuji; Hase, Eiji; Fukushima, Shuichiro; Ogura, Yuki; Yamashita, Toyonobu; Hirao, Tetsuji; Araki, Tsutomu; Yasui, Takeshi

2014-01-01

Polarization-resolved second-harmonic-generation (PR-SHG) microscopy is a powerful tool for investigating collagen fiber orientation quantitatively with low invasiveness. However, the waiting time for the mechanical polarization rotation makes it too sensitive to motion artifacts and hence has hampered its use in various applications in vivo. In the work described in this article, we constructed a motion-artifact-robust, PR-SHG microscope based on rapid polarization switching at every pixel with an electro-optic Pockells cell (PC) in synchronization with step-wise raster scanning of the focus spot and alternate data acquisition of a vertical-polarization-resolved SHG signal and a horizontal-polarization-resolved one. The constructed PC-based PR-SHG microscope enabled us to visualize orientation mapping of dermal collagen fiber in human facial skin in vivo without the influence of motion artifacts. Furthermore, it implied the location and/or age dependence of the collagen fiber orientation in human facial skin. The robustness to motion artifacts in the collagen orientation measurement will expand the application scope of SHG microscopy in dermatology and collagen-related fields. PMID:24761292

Electric Field-Assisted Orientation of Short Phosphate Glass Fibers on Stainless Steel for Biomedical Applications.

PubMed

Chen, Qiang; Jing, Jiajia; Qi, Hongfei; Ahmed, Ifty; Yang, Haiou; Liu, Xianhu; Lu, T L; Boccaccini, Aldo R

2018-04-11

Structural and compositional modifications of metallic implant surfaces are being actively investigated to achieve improved bone-to-implant bonding. In this study, a strategy to modify bulk metallic surfaces by electrophoretic deposition (EPD) of short phosphate glass fibers (sPGF) is presented. Random and aligned orientation of sPGF embedded in a poly(acrylic acid) matrix is achieved by vertical and horizontal EPD, respectively. The influence of EPD parameters on the degree of alignment is investigated to pave the way for the fabrication of highly aligned sPGF structures in large areas. Importantly, the oriented sPGF structure in the coating, owing to the synergistic effects of bioactive composition and fiber orientation, plays an important role in directional cell migration and enhanced proliferation. Moreover, gene expression of MC3T3-E1 cells cultured with different concentrations of sPGF is thoroughly assessed to elucidate the potential stimulating effect of sPGF on osteogenic differentiation. This study represents an innovative exploitation of EPD to develop textured surfaces by orientation of fibers in the macroscale, which shows great potential for directional functionalization of metallic implants.

The influence of glass fibers on elongational viscosity studied by means of optical coherence tomography and X-ray computed tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aigner, M., E-mail: michael.aigner@jku.at; Köpplmayr, T., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at; Lang, C., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at

2014-05-15

We report on the flow characteristics of glass-fiber-reinforced polymers in elongational rheometry. Unlike polymers with geometrically isotropic fillers, glass-fiber-reinforced polymers exhibit flow behavior and rheology that depend heavily on the orientation, the length distribution and the content of the fibers. One of the primary objectives of this study was to determine the effect of fiber orientation, concentration and distribution on the entrance pressure drop by means of optical coherence tomography (OCT), full-field optical coherence microscopy (FF-OCM), and X-ray computed tomography (X-CT). Both pressure drop and melt flow were analyzed using a special elongation die (Thermo Scientific X-Die [3]) for inlinemore » measurements. Samples with a variety of fiber volume fractions, fiber lengths and processing temperatures were measured.« less

Z-direction fiber orientation in paperboard

Treesearch

John M. Considine; David W. Vahey; Roland Gleisner; Alan Rudie; Sabine Rolland du Roscoat; Jean-Francis Bloch

2010-01-01

This work evaluated the use of conventional tests to show beneficial attributes of z-direction fiber orientation (ZDFO) for structural paperboards. A survey of commercial linerboards indicated the presence of ZDFO in one material that had higher Taber stiffness, out-of-plane shear strength, directional dependence of Scott internal bond strength and directional...

Fiber optic sensor and method for making

DOEpatents

Vartuli, James Scott; Bousman, Kenneth Sherwood; Deng, Kung-Li; McEvoy, Kevin Paul; Xia, Hua

2010-05-18

A fiber optic sensor including a fiber having a modified surface integral with the fiber wherein the modified surface includes an open pore network with optical agents dispersed within the open pores of the open pore network. Methods for preparing the fiber optic sensor are also provided. The fiber optic sensors can withstand high temperatures and harsh environments.

Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor

NASA Technical Reports Server (NTRS)

Vary, A.; Lark, R. F.

1978-01-01

An ultrasonic-acoustic technique was used to indicate the strength variations of tensile specimens of a graphite-epoxy composite. A stress wave factor was determined and its value was found to depend on variations of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress wave factor can indicate variations of the tensile and shear strengths of composite materials. The stress wave factor was also found to be sensitive to strength variations associated with microporosity and differences in fiber-resin ratio.

Compact Optical Fiber 3D Shape Sensor Based on a Pair of Orthogonal Tilted Fiber Bragg Gratings

NASA Astrophysics Data System (ADS)

Feng, Dingyi; Zhou, Wenjun; Qiao, Xueguang; Albert, Jacques

2015-11-01

In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal. The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end. The two groups of cladding mode resonances in the reflection spectrum respond differentially to bending, which allows for the unique determination of the magnitude and orientation of the bend plane (i.e. with a ± 180 degree uncertainty). Bending responses ranging from -0.33 to + 0.21 dB/m-1 (depending on orientation) are experimentally demonstrated with bending from 0 to 3.03 m-1. In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/μɛ.

Nondestructive testing based on scanning-from-heating approach: application to nonthrough defect detection and fiber orientation assessment

NASA Astrophysics Data System (ADS)

Belkacemi, Mohamed; Stolz, Christophe; Mathieu, Alexandre; Lemaitre, Guillaume; Massich, Joan; Aubreton, Olivier

2015-11-01

Today, industries ensure the quality of their manufactured products through computer vision techniques and nonconventional imaging. Three-dimensional (3-D) scanners and nondestructive testing (NDT) systems are commonly used independently for such applications. Furthermore, these approaches combined constitute hybrid systems, providing a 3-D reconstruction and NDT analysis. These systems, however, suffer from drawbacks such as errors during the data fusion and higher cost for manufacturers. In an attempt to solve these problems, a single active thermography system based on scanning-from-heating is proposed in this paper. In addition to 3-D digitization of the object, our contributions are twofold: (1) the nonthrough defect detection for a homogeneous metallic object and (2) fiber orientation assessment for a long fiber composite material. The experiments on steel and aluminum plates show that our method achieves the detection of nonthrough defects. Additionally, the estimation of the fiber orientation is evaluated on carbon-fiber composite material.

Effects of Constituents and Lay-up Configuration on Drop-Weight Tests of Fiber-Metal Laminates

NASA Astrophysics Data System (ADS)

Liu, Yanxiong; Liaw, Benjamin

2010-02-01

Impact responses and damage of various fiber-metal laminates were studied using a drop-weight instrument with the post-impact damage characteristics being evaluated through ultrasonic and mechanical sectioning techniques. The first severe failure induced by the low-velocity drop-weight impact occurred as delamination between the aluminum and fiber-epoxy layers at the non-impact side. It was followed by a visible shear crack in the outer aluminum layer on the non-impact face. Through-thickness shear cracks in the aluminum sheets and severe damage in the fiber laminated layers (including delamination between adjacent fiber-epoxy laminae with different fiber orientations) developed under higher energy impacts. The impact properties of fiber-metal laminates varied with different constituent materials and fiber orientations. Since it was punched through easily, the aramid-fiber reinforced fiber-metal laminates (ARALL) offered poorer impact resistance than the glass-fiber reinforced fiber-metal laminates (GLARE). Tougher and more ductile aluminum alloys improved the impact resistance. GLARE made of cross-ply prepregs provided better impact resistance than GLARE with unidirectional plies.

Wet spinning of fibers made of chitosan and chitin nanofibrils.

PubMed

Yudin, Vladimir E; Dobrovolskaya, Irina P; Neelov, Igor M; Dresvyanina, Elena N; Popryadukhin, Pavel V; Ivan'kova, Elena M; Elokhovskii, Vladimir Yu; Kasatkin, Igor A; Okrugin, Boris M; Morganti, Pierfrancesco

2014-08-08

Biocompatible and bioresorbable composite fibers consisting of chitosan filled with anisotropic chitin nanofibrils with the length of 600-800 nm and cross section of about 11-12 nm as revealed by SEM and XRD were prepared by coagulation. Both chitin and chitosan components of the composite fibers displayed preferred orientations. Orientation of chitosan molecules induced by chitin nanocrystallites was confirmed by molecular modeling. The incorporation of 0.1-0.3 wt.% of chitin nanofibrils into chitosan matrix led to an increase in strength and Young modulus of the composite fibers. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of Fiber-Optical Techniques in the Access Transmission and Backbone Transport of Mobile Networks

NASA Astrophysics Data System (ADS)

Hilt, Attila; Pozsonyi, László

2012-09-01

Fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In the last decade, there has also been an enormous increase of user data visible in mobile systems. The importance of fiber-optical techniques within the fixed transmission/transport networks of mobile systems is therefore inevitably increasing. This article summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in second-generation networks.

Mechanism of calcite co-orientation in the sea urchin tooth.

PubMed

Killian, Christopher E; Metzler, Rebecca A; Gong, Y U T; Olson, Ian C; Aizenberg, Joanna; Politi, Yael; Wilt, Fred H; Scholl, Andreas; Young, Anthony; Doran, Andrew; Kunz, Martin; Tamura, Nobumichi; Coppersmith, Susan N; Gilbert, P U P A

2009-12-30

Sea urchin teeth are remarkable and complex calcite structures, continuously growing at the forming end and self-sharpening at the mature grinding tip. The calcite (CaCO(3)) crystals of tooth components, plates, fibers, and a high-Mg polycrystalline matrix, have highly co-oriented crystallographic axes. This ability to co-orient calcite in a mineralized structure is shared by all echinoderms. However, the physico-chemical mechanism by which calcite crystals become co-oriented in echinoderms remains enigmatic. Here, we show differences in calcite c-axis orientations in the tooth of the purple sea urchin ( Strongylocentrotus purpuratus ), using high-resolution X-ray photoelectron emission spectromicroscopy (X-PEEM) and microbeam X-ray diffraction (muXRD). All plates share one crystal orientation, propagated through pillar bridges, while fibers and polycrystalline matrix share another orientation. Furthermore, in the forming end of the tooth, we observe that CaCO(3) is present as amorphous calcium carbonate (ACC). We demonstrate that co-orientation of the nanoparticles in the polycrystalline matrix occurs via solid-state secondary nucleation, propagating out from the previously formed fibers and plates, into the amorphous precursor nanoparticles. Because amorphous precursors were observed in diverse biominerals, solid-state secondary nucleation is likely to be a general mechanism for the co-orientation of biomineral components in organisms from different phyla.

Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

PubMed

Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

2015-01-01

The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

PubMed Central

Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

2015-01-01

The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

A constitutive relation for the viscous flow of an oriented fiber assembly

NASA Technical Reports Server (NTRS)

Pipes, R. B.; Hearle, J. W. S.; Beaussart, A. J.; Sastry, A. M.; Okine, R. K.

1991-01-01

A constitutive relation for an equivalent, homogeneous fluid is developed for the anisotropic viscous flow of an oriented assembly of discontinuous fibers suspended in a viscous fluid. The anisotropic viscous compliance matrix can be expressed in terms of three constants by assuming the equivalent fluid to be incompressible and the microstructure to have axial symmetry (transversely isotropic). By means of a micromechanics analysis, the three terms of the constitutive relation are expressed in terms of the viscosity of the matrix fluid, the fiber aspect ratio, and the fiber volume fraction. A comparison of the viscosity terms reveals that the elongational viscosity in the fiber direction varies as the square of the fiber aspect ratio and a complex function of the fiber volume fraction. Furthermore, the ratio of the axial elongational viscosity to the transverse elongational viscosity and both axial and transverse shear viscosities was shown to be 10 exp 4 - 10 exp 6 for fiber aspect ratio of 100-1000, except at extreme values of the fiber volume fraction.

Localized Statistics for DW-MRI Fiber Bundle Segmentation

PubMed Central

Lankton, Shawn; Melonakos, John; Malcolm, James; Dambreville, Samuel; Tannenbaum, Allen

2013-01-01

We describe a method for segmenting neural fiber bundles in diffusion-weighted magnetic resonance images (DWMRI). As these bundles traverse the brain to connect regions, their local orientation of diffusion changes drastically, hence a constant global model is inaccurate. We propose a method to compute localized statistics on orientation information and use it to drive a variational active contour segmentation that accurately models the non-homogeneous orientation information present along the bundle. Initialized from a single fiber path, the proposed method proceeds to capture the entire bundle. We demonstrate results using the technique to segment the cingulum bundle and describe several extensions making the technique applicable to a wide range of tissues. PMID:23652079

Connective Tissue Characteristics around Healing Abutments of Different Geometries: New Methodological Technique under Circularly Polarized Light.

PubMed

Delgado-Ruiz, Rafael Arcesio; Calvo-Guirado, Jose Luis; Abboud, Marcus; Ramirez-Fernandez, Maria Piedad; Maté-Sánchez de Val, José Eduardo; Negri, Bruno; Gomez-Moreno, Gerardo; Markovic, Aleksa

2015-08-01

To describe contact, thickness, density, and orientation of connective tissue fibers around healing abutments of different geometries by means of a new method using coordinates. Following the bilateral extraction of mandibular premolars (P2, P3, and P4) from six fox hound dogs and a 2-month healing period, 36 titanium implants were inserted, onto which two groups of healing abutments of different geometry were screwed: Group A (concave abutments) and Group B (wider healing abutment). After 3 months the animals were sacrificed and samples extracted containing each implant and surrounding soft and hard tissues. Histological analysis was performed without decalcifying the samples by means of circularly polarized light under optical microscope and a system of vertical and horizontal coordinates across all the connective tissue in an area delimited by the implant/abutment, epithelium, and bone tissue. In no case had the connective tissue formed a connection to the healing abutment/implant in the internal zone; a space of 35 ± 10 μm separated the connective tissue fibers from the healing abutment surface. The total thickness of connective tissue in the horizontal direction was significantly greater in the medial zone in Group B than in Group A (p < .05). The orientation of the fibers varied according to the coordinate area so that internal coordinates showed a higher percentage of parallel fibers in Group A (p < .05) and a higher percentage of oblique fibers in Group B (p < .05); medial coordinates showed more oblique fibers (p < .05); and the area of external coordinates showed the highest percentage of perpendicular fibers (p < .05). The fiber density was higher in the basal and medial areas (p < .05). Abutment geometry influences the orientation of collagen fibers; therefore, an abutment with a profile wider than the implant platform favors oblique and perpendicular orientation of collagen fibers and greater connective tissue thickness. © 2013 Wiley Periodicals, Inc.

Simulation of the mechanical behavior of random fiber networks with different microstructure.

PubMed

Hatami-Marbini, H

2018-05-24

Filamentous protein networks are broadly encountered in biological systems such as cytoskeleton and extracellular matrix. Many numerical studies have been conducted to better understand the fundamental mechanisms behind the striking mechanical properties of these networks. In most of these previous numerical models, the Mikado algorithm has been used to represent the network microstructure. Here, a different algorithm is used to create random fiber networks in order to investigate possible roles of architecture on the elastic behavior of filamentous networks. In particular, random fibrous structures are generated from the growth of individual fibers from random nucleation points. We use computer simulations to determine the mechanical behavior of these networks in terms of their model parameters. The findings are presented and discussed along with the response of Mikado fiber networks. We demonstrate that these alternative networks and Mikado networks show a qualitatively similar response. Nevertheless, the overall elasticity of Mikado networks is stiffer compared to that of the networks created using the alternative algorithm. We describe the effective elasticity of both network types as a function of their line density and of the material properties of the filaments. We also characterize the ratio of bending and axial energy and discuss the behavior of these networks in terms of their fiber density distribution and coordination number.

Orientational alignment in solids from bidimensional isotropic-anisotropic nuclear magnetic resonance spectroscopy: applications to the analysis of aramide fibers.

PubMed

Sachleben, J R; Frydman, L

1997-02-01

The use of two-dimensional isotropic-anisotropic correlation spectroscopy for the analysis of orientational alignment in solids is presented. The theoretical background and advantages of this natural-abundance 13C NMR method of measurement are discussed, and demonstrated with a series of powder and single-crystal variable-angle correlation spectroscopy (VACSY) experiments on model systems. The technique is subsequently employed to analyze the orientational distributions of three polymer fibers: Kevlar 29, Kevlar 49 and Kevlar 149. Using complementary two-dimensional NMR data recorded on synthetic samples of poly(p-phenyleneterephthalamide), the precursor of Kevlar, it was found that these commercial fibers possess molecules distributed over a very narrow orientational range with respect to the macroscopic director. The widths measured for these director distribution arrangements were (12 +/- 1.5) degrees for Kevlar 29, (15 +/- 1.5) degrees for Kevlar 49, and (8 +/- 1.5) degrees for Kevlar 149. These figures compare well with previous results obtained for non-commercial fiber samples derived from the same polymer.

Fracture of Composite Compact Tension Specimens

DTIC Science & Technology

1975-01-01

E: lb/in.; X 10* M.: Fiber Volume, % 1002 S- glass /epoxy Unidirectional Crossply 6.9 4.7 2.3 4.7 1.0 1.1 0.28 0.14 55 MOD 1-5208...configuration used in most of the fracture experiments is shown in Fig. 1. In unidirectional S- glass /epoxy specimens the fiber direction with respect to...conducted only with 0° or 90° fiber orientation. Cross-ply specimens of both S- glass and graphite were tested with the outer plies oriented at 0°, 45

Developing a tissue-engineered neural-electrical relay using encapsulated neuronal constructs on conducting polymer fibers.

PubMed

Cullen, D Kacy; R Patel, Ankur; Doorish, John F; Smith, Douglas H; Pfister, Bryan J

2008-12-01

Neural-electrical interface platforms are being developed to extracellularly monitor neuronal population activity. Polyaniline-based electrically conducting polymer fibers are attractive substrates for sustained functional interfaces with neurons due to their flexibility, tailored geometry and controlled electro-conductive properties. In this study, we addressed the neurobiological considerations of utilizing small diameter (<400 microm) fibers consisting of a blend of electrically conductive polyaniline and polypropylene (PA-PP) as the backbone of encapsulated tissue-engineered neural-electrical relays. We devised new approaches to promote survival, adhesion and neurite outgrowth of primary dorsal root ganglion neurons on PA-PP fibers. We attained a greater than ten-fold increase in the density of viable neurons on fiber surfaces to approximately 700 neurons mm(-2) by manipulating surrounding surface charges to bias settling neuronal suspensions toward fibers coated with cell-adhesive ligands. This stark increase in neuronal density resulted in robust neuritic extension and network formation directly along the fibers. Additionally, we encapsulated these neuronal networks on PA-PP fibers using agarose to form a protective barrier while potentially facilitating network stability. Following encapsulation, the neuronal networks maintained integrity, high viability (>85%) and intimate adhesion to PA-PP fibers. These efforts accomplished key prerequisites for the establishment of functional electrical interfaces with neuronal populations using small diameter PA-PP fibers-specifically, improved neurocompatibility, high-density neuronal adhesion and neuritic network development directly on fiber surfaces.

Buying Fiber-Optic Networks.

ERIC Educational Resources Information Center

Fickes, Michael

2003-01-01

Describes consortia formed by college and university administrators to buy, manage, and maintain their own fiber-optic networks with the goals of cutting costs of leasing fiber-optic cable and planning for the future. Growth capacity is the real advantage of owning fiber-optic systems. (SLD)

Effect of cold drawing on mechanical properties of biodegradable fibers.

PubMed

La Mantia, Francesco Paolo; Ceraulo, Manuela; Mistretta, Maria Chiara; Morreale, Marco

2017-01-26

Biodegradable polymers are currently gaining importance in several fields, because they allow mitigation of the impact on the environment related to disposal of traditional, nonbiodegradable polymers, as well as reducing the utilization of oil-based sources (when they also come from renewable resources). Fibers made of biodegradable polymers are of particular interest, though, it is not easy to obtain polymer fibers with suitable mechanical properties and to tailor these to the specific application. The main ways to tailor the mechanical properties of a given biodegradable polymer fiber are based on crystallinity and orientation control. However, crystallinity can only marginally be modified during processing, while orientation can be controlled, either during hot drawing or cold stretching. In this paper, a systematic investigation of the influence of cold stretching on the mechanical and thermomechanical properties of fibers prepared from different biodegradable polymer systems was carried out. Rheological and thermal characterization helped in interpreting the orientation mechanisms, also on the basis of the molecular structure of the polymer systems. It was found that cold drawing strongly improved the elastic modulus, tensile strength and thermomechanical resistance of the fibers, in comparison with hot-spun fibers. The elastic modulus showed higher increment rates in the biodegradable systems upon increasing the draw ratio.

Investigation of dynamic properties of a polymer matrix composite with different angles of fiber orientations

NASA Astrophysics Data System (ADS)

Kadioglu, F.; Coskun, T.; Elfarra, M.

2018-05-01

For the dynamic values of fiber-reinforced polymer matrix composite materials, elastic modulus and damping values are emphasized, and the two are desired to be high as much as possible, as the first is related to load bearing capacity, the latter provides the capability of energy absorption. In the composites, while fibers are usually utilized for reinforcement providing high elastic modulus and so high strength, matrix introduces a medium for high damping. Correct measurement of damping values is a critical step in designing composite materials. The aim of the current study is to measure the dynamic values of a glass fiber-reinforced polymer matrix composite, Hexply 913/33%/UD280, produced by Hexcel, using a vibrating beam technique. The specimens with different angles of fiber orientations (0, ±10°, ±20°, ±35, ±45°, ±55°, ±70, ±80 and 90) were manufactured from the composite prepreg and subjected to the clamped-free boundary conditions. Two different methods, the half power bandwidth and the logarithmic free decay, were used to measure the damping values to be able to compare the results. It has been revealed that the dynamic values are affected by the fiber orientations; for high flexural modulus the specimens with small angles of orientation, but for high damping those with large angles of orientation should be preferred. In general, the results are comparable, and the free decay method gave smaller values compared to the bandwidth method, with a little exception. It is suggested that the results (data) obtained from the test can be used for modal analysis reliably.

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes

PubMed Central

You, Ilhwan; Yoo, Doo-Yeol; Kim, Soonho; Kim, Min-Jae; Zi, Goangseup

2017-01-01

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state. PMID:29109388

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes.

PubMed

You, Ilhwan; Yoo, Doo-Yeol; Kim, Sooho; Kim, Min-Jae; Zi, Goangseup

2017-10-29

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Killian, Christopher; Metzler, Rebecca; Gong, Y. U. T.

Sea urchin teeth are remarkable and complex calcite structures, continuously growing at the forming end and self-sharpening at the mature grinding tip. The calcite (CaCO{sub 3}) crystals of tooth components, plates, fibers, and a high-Mg polycrystalline matrix, have highly co-oriented crystallographic axes. This ability to co-orient calcite in a mineralized structure is shared by all echinoderms. However, the physico-chemical mechanism by which calcite crystals become co-oriented in echinoderms remains enigmatic. Here, we show differences in calcite c-axis orientations in the tooth of the purple sea urchin (Strongylocentrotus purpuratus), using high-resolution X-ray photoelectron emission spectromicroscopy (X-PEEM) and microbeam X-ray diffraction ({mu}XRD).more » All plates share one crystal orientation, propagated through pillar bridges, while fibers and polycrystalline matrix share another orientation. Furthermore, in the forming end of the tooth, we observe that CaCO{sub 3} is present as amorphous calcium carbonate (ACC). We demonstrate that co-orientation of the nanoparticles in the polycrystalline matrix occurs via solid-state secondary nucleation, propagating out from the previously formed fibers and plates, into the amorphous precursor nanoparticles. Because amorphous precursors were observed in diverse biominerals, solid-state secondary nucleation is likely to be a general mechanism for the co-orientation of biomineral components in organisms from different phyla.« less

Analysis of Orientations of Collagen Fibers by Novel Fiber-Tracking Software

NASA Astrophysics Data System (ADS)

Wu, Jun; Rajwa, Bartlomiej; Filmer, David L.; Hoffmann, Christoph M.; Yuan, Bo; Chiang, Ching-Shoei; Sturgis, Jennie; Robinson, J. Paul

2003-12-01

Recent evidence supports the notion that biological functions of extracellular matrix (ECM) are highly correlated to not only its composition but also its structure. This article integrates confocal microscopy imaging and image-processing techniques to analyze the microstructural properties of ECM. This report describes a two- and three-dimensional fiber middle-line tracing algorithm that may be used to quantify collagen fibril organization. We utilized computer simulation and statistical analysis to validate the developed algorithm. These algorithms were applied to confocal images of collagen gels made with reconstituted bovine collagen type I, to demonstrate the computation of orientations of individual fibers.

Predictive Engineering Tools for Injection-molded Long-Carbon-Fiber Thermoplastic Composites - FY 2014 Third Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Sanborn, Scott E.; Mathur, Raj N.

2014-08-15

This report describes the technical progresses made during the third quarter of FY 2014: 1) Autodesk introduced the options for fiber inlet condition to the 3D solver. These options are already available in the mid-plane/dual domain solver. 2) Autodesk improved the accuracy of 3D fiber orientation calculation around the gate. 3) Autodesk received consultant services from Prof. C.L. Tucker at the University of Illinois on the implementation of the reduced order model for fiber length, and discussed with Prof. Tucker the methods to reduce memory usage. 4) PlastiComp delivered to PNNL center-gated and edge-fan-gated 20-wt% to 30-wt% LCF/PP and LCF/PA66more » (7”x7”x1/8”) plaques molded by the in-line direct injection molding (D-LFT) process. 5) PlastiComp molded ASTM tensile, flexural and impact bars under the same D-LFT processing conditions used for plaques for Certification of Assessment and ascertaining the resultant mechanical properties. 6) Purdue developed a new polishing routine, utilizing the automated polishing machine, to reduce fiber damage during surface preparation. 7) Purdue used a marker-based watershed segmentation routine, in conjunction with a hysteresis thresholding technique, for fiber segmentation during fiber orientation measurement. 8) Purdue validated Purdue’s fiber orientation measurement method using the previous fiber orientation data obtained from the Leeds machine and manually measured data by the University of Illinois. 9) PNNL conducted ASMI mid-plane analyses for a 30wt% LCF/PP plaque and compared the predicted fiber orientations with the measured data provided by Purdue University at the selected locations on this plaque. 10) PNNL put together the DOE 2014 Annual Merit Review (AMR) presentation with the team and presented it at the AMR meetings on June 17, 2014. 11) PNNL built ASMI dual domain models for the Toyota complex part and commenced mold filling analyses of the complex part with different wall thicknesses in order to support part molding. 12) Toyota and Magna discussed with PNNL on tool modification for molding the complex part. Toyota sent the CAD files of the complex part to PNNL to build ASMI models of the part for mold filling analysis to provide guidance to tooling and part molding.« less

Burning characteristics and fiber retention of graphite/resin matrix composites

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

Graphite fiber reinforced resin matrix composites were subjected to controlled burning conditions to determine their burning characteristics and fiber retention properties. Two types of burning equipment were used. Small samples were burned with a natural gas fired torch to study the effects of fiber orientation and structural flaws such as holes and slits that were machined into the laminates. Larger laminate samples were burned in a Heat Release Rate Calorimeter. Unidirectional epoxy/graphite and polyimide/graphite composites and boron powder filled samples of each of the two composite systems were burn tested and exposed to a thermal radiation. The effects of fiber orientation, flaws, and boron filler additives to the resins were evaluated. A high char forming polyimide resin was no more effective in retaining graphite fibers than a low char forming epoxy resin when burning in air.

Neural networks within multi-core optic fibers

PubMed Central

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-01-01

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks. PMID:27383911

Neural networks within multi-core optic fibers.

PubMed

Cohen, Eyal; Malka, Dror; Shemer, Amir; Shahmoon, Asaf; Zalevsky, Zeev; London, Michael

2016-07-07

Hardware implementation of artificial neural networks facilitates real-time parallel processing of massive data sets. Optical neural networks offer low-volume 3D connectivity together with large bandwidth and minimal heat production in contrast to electronic implementation. Here, we present a conceptual design for in-fiber optical neural networks. Neurons and synapses are realized as individual silica cores in a multi-core fiber. Optical signals are transferred transversely between cores by means of optical coupling. Pump driven amplification in erbium-doped cores mimics synaptic interactions. We simulated three-layered feed-forward neural networks and explored their capabilities. Simulations suggest that networks can differentiate between given inputs depending on specific configurations of amplification; this implies classification and learning capabilities. Finally, we tested experimentally our basic neuronal elements using fibers, couplers, and amplifiers, and demonstrated that this configuration implements a neuron-like function. Therefore, devices similar to our proposed multi-core fiber could potentially serve as building blocks for future large-scale small-volume optical artificial neural networks.

Arrays of Regenerated Fiber Bragg Gratings in Non-Hydrogen-Loaded Photosensitive Fibers for High-Temperature Sensor Networks

PubMed Central

Lindner, Eric; Chojetztki, Christoph; Brueckner, Sven; Becker, Martin; Rothhardt, Manfred; Vlekken, Johan; Bartelt, Hartmut

2009-01-01

We report about the possibility of using regenerated fiber Bragg gratings generated in photosensitive fibers without applying hydrogen loading for high temperature sensor networks. We use a thermally induced regenerative process which leads to a secondary increase in grating reflectivity. This refractive index modification has shown to become more stable after the regeneration up to temperatures of 600 °C. With the use of an interferometric writing technique, it is possible also to generate arrays of regenerated fiber Bragg gratings for sensor networks. PMID:22408510

Self-healing ring-based WDM-PON

NASA Astrophysics Data System (ADS)

Zhou, Yang; Gan, Chaoqin; Zhu, Long

2010-05-01

In this paper, a survivable ring-based wavelength-division-multiplexing (WDM)-passive optical network (PON) for fiber protection is proposed. Protections for feeder fiber and distributed fiber are independent in the scheme. Optical line terminal (OLT) and optical network units (ONUs) can automatically switch to protection link when fiber failure occurs. Protection distributed fiber is not required in the scheme. Cost-effective components are used in ONUs to minimize costs of network. A simulation study is performed to demonstrate the scheme. Its result shows good performance of upstream and downstream signals.

Fiber optic sensors; Proceedings of the Meeting, Cannes, France, November 26, 27, 1985

NASA Technical Reports Server (NTRS)

Arditty, Herve J. (Editor); Jeunhomme, Luc B. (Editor)

1986-01-01

The conference presents papers on distributed sensors and sensor networks, signal processing and detection techniques, temperature measurements, chemical sensors, and the measurement of pressure, strain, and displacements. Particular attention is given to optical fiber distributed sensors and sensor networks, tactile sensing in robotics using an optical network and Z-plane techniques, and a spontaneous Raman temperature sensor. Other topics include coherence in optical fiber gyroscopes, a high bandwidth two-phase flow void fraction fiber optic sensor, and a fiber-optic dark-field microbend sensor.

In Vivo Orientation of Single Myosin Lever Arms in Zebrafish Skeletal Muscle

PubMed Central

Sun, Xiaojing; Ekker, Stephen C.; Shelden, Eric A.; Takubo, Naoko; Wang, Yihua; Burghardt, Thomas P.

2014-01-01

Cardiac and skeletal myosin assembled in the muscle lattice power contraction by transducing ATP free energy into the mechanical work of moving actin. Myosin catalytic/lever-arm domains comprise the transduction/mechanical coupling machinery that move actin by lever-arm rotation. In vivo, myosin is crowded and constrained by the fiber lattice as side chains are mutated and otherwise modified under normal, diseased, or aging conditions that collectively define the native myosin environment. Single-myosin detection uniquely defines bottom-up characterization of myosin functionality. The marriage of in vivo and single-myosin detection to study zebrafish embryo models of human muscle disease is a multiscaled technology that allows one-to-one registration of a selected myosin molecular alteration with muscle filament-sarcomere-cell-fiber-tissue-organ- and organism level phenotypes. In vivo single-myosin lever-arm orientation was observed at superresolution using a photoactivatable-green-fluorescent-protein (PAGFP)-tagged myosin light chain expressed in zebrafish skeletal muscle. By simultaneous observation of multiphoton excitation fluorescence emission and second harmonic generation from myosin, we demonstrated tag specificity for the lever arm. Single-molecule detection used highly inclined parallel beam illumination and was verified by quantized photoactivation and photobleaching. Single-molecule emission patterns from relaxed muscle in vivo provided extensive superresolved dipole orientation constraints that were modeled using docking scenarios generated for the myosin (S1) and GFP crystal structures. The dipole orientation data provided sufficient constraints to estimate S1/GFP coordination. The S1/GFP coordination in vivo is rigid and the lever-arm orientation distribution is well-ordered in relaxed muscle. For comparison, single myosins in relaxed permeabilized porcine papillary muscle fibers indicated slightly differently oriented lever arms and rigid S1/GFP coordination. Lever arms in both muscles indicated one preferred spherical polar orientation and widely distributed azimuthal orientations relative to the fiber symmetry axis. Cardiac myosin is more radially displaced from the fiber axis. Probe rigidity implies the PAGFP tag reliably indicates cross-bridge orientation in situ and in vivo. PMID:25229148

The formation of web-like connection among electrospun chitosan/PVA fiber network by the reinforcement of ellipsoidal calcium carbonate.

PubMed

Sambudi, Nonni Soraya; Kim, Minjeong G; Park, Seung Bin

2016-03-01

The electrospun fibers consist of backbone fibers and nano-branch network are synthesized by loading of ellipsoidal calcium carbonate in the mixture of chitosan/poly(vinyl alcohol) (PVA) followed by electrospinning. The synthesized ellipsoidal calcium carbonate is in submicron size (730.7±152.4 nm for long axis and 212.6±51.3 nm for short axis). The electrospun backbone fibers experience an increasing in diameter by loading of calcium carbonate from 71.5±23.4 nm to 281.9±51.2 nm. The diameters of branch fibers in the web-network range from 15 nm to 65 nm with most distributions of fibers are in 30-35 nm. Calcium carbonate acts as reinforcing agent to improve the mechanical properties of fibers. The optimum value of Young's modulus is found at the incorporation of 3 wt.% of calcium carbonate in chitosan/PVA fibers, which is enhanced from 15.7±3 MPa to 432.4±94.3 MPa. On the other hand, the ultimate stress of fibers experiences a decrease. This result shows that the fiber network undergoes changes from flexible to more stiff by the inclusion of calcium carbonate. The thermal analysis results show that the crystallinity of polymer is changed by the existence of calcium carbonate in the fiber network. The immersion of fibers in simulated body fluid (SBF) results in the formation of apatite on the surface of fibers. Copyright © 2015 Elsevier B.V. All rights reserved.

Correlation Function Approach for Estimating Thermal Conductivity in Highly Porous Fibrous Materials

NASA Technical Reports Server (NTRS)

Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

2011-01-01

Heat transport in highly porous fiber networks is analyzed via two-point correlation functions. Fibers are assumed to be long and thin to allow a large number of crossing points per fiber. The network is characterized by three parameters: the fiber aspect ratio, the porosity and the anisotropy of the structure. We show that the effective thermal conductivity of the system can be estimated from knowledge of the porosity and the correlation lengths of the correlation functions obtained from a fiber structure image. As an application, the effects of the fiber aspect ratio and the network anisotropy on the thermal conductivity is studied.

The resilient hybrid fiber sensor network with self-healing function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Shibo, E-mail: Shibo-Xu@tju.edu.cn; Liu, Tiegen; Ge, Chunfeng

This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working inmore » FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.« less

Collagen Fiber Orientation in Primate Long Bones.

PubMed

Warshaw, Johanna; Bromage, Timothy G; Terranova, Carl J; Enlow, Donald H

2017-07-01

Studies of variation in orientation of collagen fibers within bone have lead to the proposition that these are preferentially aligned to accommodate different kinds of load, with tension best resisted by fibers aligned longitudinally relative to the load, and compression best resisted by transversely aligned fibers. However, previous studies have often neglected to consider the effect of developmental processes, including constraints on collagen fiber orientation (CFO), particularly in primary bone. Here we use circularly polarized light microscopy to examine patterns of CFO in cross-sections from the midshaft femur, humerus, tibia, radius, and ulna in a range of living primate taxa with varied body sizes, phylogenetic relationships and positional behaviors. We find that a preponderance of longitudinally oriented collagen is characteristic of both periosteal primary and intracortically remodeled bone. Where variation does occur among groups, it is not simply understood via interpretations of mechanical loads, although prioritized adaptations to tension and/or shear are considered. While there is some suggestion that CFO may correlate with body size, this relationship is neither consistent nor easily explicable through consideration of size-related changes in mechanical adaptation. The results of our study indicate that there is no clear relationship between CFO and phylogenetic status. One of the principle factors accounting for the range of variation that does exist is primary tissue type, where slower depositing bone is more likely to comprise a larger proportion of oblique to transverse collagen fibers. Anat Rec, 300:1189-1207, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Evolution of the three-dimensional collagen structure in vascular walls during deformation: an in situ mechanical testing under multiphoton microscopy observation.

PubMed

Nierenberger, Mathieu; Fargier, Guillaume; Ahzi, Saïd; Rémond, Yves

2015-08-01

The collagen fibers' three-dimensional architecture has a strong influence on the mechanical behavior of biological tissues. To accurately model this behavior, it is necessary to get some knowledge about the structure of the collagen network. In the present paper, we focus on the in situ characterization of the collagenous structure, which is present in porcine jugular vein walls. An observation of the vessel wall is first proposed in an unloaded configuration. The vein is then put into a mechanical tensile testing device. As the vein is stretched, three-dimensional images of its collagenous structure are acquired using multiphoton microscopy. Orientation analyses are provided for the multiple images recorded during the mechanical test. From these analyses, the reorientation of the two families of collagen fibers existing in the vein wall is quantified. We noticed that the reorientation of the fibers stops as the tissue stiffness starts decreasing, corresponding to the onset of damage. Besides, no relevant evolutions of the out of plane collagen orientations were observed. Due to the applied loading, our analysis also allowed for linking the stress relaxation within the tissue to its internal collagenous structure. Finally, this analysis constitutes the first mechanical test performed under a multiphoton microscope with a continuous three-dimensional observation of the tissue structure all along the test. It allows for a quantitative evaluation of microstructural parameters combined with a measure of the global mechanical behavior. Such data are useful for the development of structural mechanical models for living tissues.

Relative Impacts of Low Permeability Subsurface Deposits on Recharge Basin Infiltration Rates

NASA Astrophysics Data System (ADS)

Oconnell, P.; Becker, M.; Pham, C.; Rodriguez, G.; Hutchinson, A.; Plumlee, M.

2017-12-01

Artificial recharge of aquifers through spreading basins has become an important component of water management in semi-arid climates. The rate at which water can be recharged in these basins is limited by the natural vertical permeability of the underlying deposits which may be highly variable both laterally and vertically. To help understand hydrostratigraphic controls on recharge, a newly constructed basin was surveyed and instrumented. Prior to flooding the basin, lithology was characterized by shallow hand coring, direct push coring, ground penetrating radar, and electrical resistivity. After flooding, recharge was monitored through piezometers, electrical resistivity, and a network of fiber optic distributed temperature sensing (DTS). The DTS network used temperature as a tracer to measure infiltration rate on 25 cm intervals both laterally and vertically. Several hundred paired DTS time series datasets (from fiber optic cables located at 0 and 0.5 meters below ground surface) were processed with the cross-wavelet transform (XWT) to calculate spatially and temporally continuous infiltration rates, which can be interpolated and animated to visualize heterogeneity. Time series data from 8-meter deep, vertically oriented DTS cables reveal depth intervals where infiltration rates vary. Inverted resistivity sections from repeated dipole-dipole surveys along the sidewall of a spreading basin exhibit a positive correlation with the distribution of relatively high and low infiltration rates, indicating zones of preferential downward (efficient) and lateral (inefficient) flow, respectively. In contrast to other monitored basins, no perching was observed in the vertically oriented DTS cables. The variation in recharge across the basin and the appearance of subsurface lateral flow can be explained in context of the alluvial depositional environment.

Recent progress in distributed optical fiber Raman photon sensors at China Jiliang University

NASA Astrophysics Data System (ADS)

Zhang, Zaixuan; Wang, Jianfeng; Li, Yi; Gong, Huaping; Yu, Xiangdong; Liu, Honglin; Jin, Yongxing; Kang, Juan; Li, Chenxia; Zhang, Wensheng; Zhang, Wenping; Niu, Xiaohui; Sun, Zhongzhou; Zhao, Chunliu; Dong, Xinyong; Jin, Shangzhong

2012-06-01

A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University (CJLU) is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers (BOTDAs) integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network (Rayleigh, Raman, and Brillouin scattering) is a 3S (smart materials, smart structure, and smart skill) system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.

Microstructure Imaging of Crossing (MIX) White Matter Fibers from diffusion MRI

PubMed Central

Farooq, Hamza; Xu, Junqian; Nam, Jung Who; Keefe, Daniel F.; Yacoub, Essa; Georgiou, Tryphon; Lenglet, Christophe

2016-01-01

Diffusion MRI (dMRI) reveals microstructural features of the brain white matter by quantifying the anisotropic diffusion of water molecules within axonal bundles. Yet, identifying features such as axonal orientation dispersion, density, diameter, etc., in complex white matter fiber configurations (e.g. crossings) has proved challenging. Besides optimized data acquisition and advanced biophysical models, computational procedures to fit such models to the data are critical. However, these procedures have been largely overlooked by the dMRI microstructure community and new, more versatile, approaches are needed to solve complex biophysical model fitting problems. Existing methods are limited to models assuming single fiber orientation, relevant to limited brain areas like the corpus callosum, or multiple orientations but without the ability to extract detailed microstructural features. Here, we introduce a new and versatile optimization technique (MIX), which enables microstructure imaging of crossing white matter fibers. We provide a MATLAB implementation of MIX, and demonstrate its applicability to general microstructure models in fiber crossings using synthetic as well as ex-vivo and in-vivo brain data. PMID:27982056

DisAp-dependent striated fiber elongation is required to organize ciliary arrays

PubMed Central

Galati, Domenico F.; Bonney, Stephanie; Kronenberg, Zev; Clarissa, Christina; Yandell, Mark; Elde, Nels C.; Jerka-Dziadosz, Maria; Giddings, Thomas H.; Frankel, Joseph

2014-01-01

Cilia-organizing basal bodies (BBs) are microtubule scaffolds that are visibly asymmetrical because they have attached auxiliary structures, such as striated fibers. In multiciliated cells, BB orientation aligns to ensure coherent ciliary beating, but the mechanisms that maintain BB orientation are unclear. For the first time in Tetrahymena thermophila, we use comparative whole-genome sequencing to identify the mutation in the BB disorientation mutant disA-1. disA-1 abolishes the localization of the novel protein DisAp to T. thermophila striated fibers (kinetodesmal fibers; KFs), which is consistent with DisAp’s similarity to the striated fiber protein SF-assemblin. We demonstrate that DisAp is required for KFs to elongate and to resist BB disorientation in response to ciliary forces. Newly formed BBs move along KFs as they approach their cortical attachment sites. However, because they contain short KFs that are rotated, BBs in disA-1 cells display aberrant spacing and disorientation. Therefore, DisAp is a novel KF component that is essential for force-dependent KF elongation and BB orientation in multiciliary arrays. PMID:25533842

Nanofiber Orientation and Surface Functionalization Modulate Human Mesenchymal Stem Cell Behavior In Vitro

PubMed Central

Kolambkar, Yash M.; Bajin, Mehmet; Wojtowicz, Abigail; Hutmacher, Dietmar W.; García, Andrés J.

2014-01-01

Electrospun nanofiber meshes have emerged as a new generation of scaffold membranes possessing a number of features suitable for tissue regeneration. One of these features is the flexibility to modify their structure and composition to orchestrate specific cellular responses. In this study, we investigated the effects of nanofiber orientation and surface functionalization on human mesenchymal stem cell (hMSC) migration and osteogenic differentiation. We used an in vitro model to examine hMSC migration into a cell-free zone on nanofiber meshes and mitomycin C treatment to assess the contribution of proliferation to the observed migration. Poly (ɛ-caprolactone) meshes with oriented topography were created by electrospinning aligned nanofibers on a rotating mandrel, while randomly oriented controls were collected on a stationary collector. Both aligned and random meshes were coated with a triple-helical, type I collagen-mimetic peptide, containing the glycine-phenylalanine-hydroxyproline-glycine-glutamate-arginine (GFOGER) motif. Our results indicate that nanofiber GFOGER peptide functionalization and orientation modulate cellular behavior, individually, and in combination. GFOGER significantly enhanced the migration, proliferation, and osteogenic differentiation of hMSCs on nanofiber meshes. Aligned nanofiber meshes displayed increased cell migration along the direction of fiber orientation compared to random meshes; however, fiber alignment did not influence osteogenic differentiation. Compared to each other, GFOGER coating resulted in a higher proliferation-driven cell migration, whereas fiber orientation appeared to generate a larger direct migratory effect. This study demonstrates that peptide surface modification and topographical cues associated with fiber alignment can be used to direct cellular behavior on nanofiber mesh scaffolds, which may be exploited for tissue regeneration. PMID:24020454

On-Board Fiber-Optic Network Architectures for Radar and Avionics Signal Distribution

NASA Technical Reports Server (NTRS)

Alam, Mohammad F.; Atiquzzaman, Mohammed; Duncan, Bradley B.; Nguyen, Hung; Kunath, Richard

2000-01-01

Continued progress in both civil and military avionics applications is overstressing the capabilities of existing radio-frequency (RF) communication networks based on coaxial cables on board modem aircrafts. Future avionics systems will require high-bandwidth on- board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fiber optic communication technology can meet all these challenges in a cost-effective manner. Recently, digital fiber-optic communication systems, where a fiber-optic network acts like a local area network (LAN) for digital data communications, have become a topic of extensive research and development. Although a fiber-optic system can be designed to transport radio-frequency (RF) signals, the digital fiber-optic systems under development today are not capable of transporting microwave and millimeter-wave RF signals used in radar and avionics systems on board an aircraft. Recent advances in fiber optic technology, especially wavelength division multiplexing (WDM), has opened a number of possibilities for designing on-board fiber optic networks, including all-optical networks for radar and avionics RF signal distribution. In this paper, we investigate a number of different novel approaches for fiber-optic transmission of on-board VHF and UHF RF signals using commercial off-the-shelf (COTS) components. The relative merits and demerits of each architecture are discussed, and the suitability of each architecture for particular applications is pointed out. All-optical approaches show better performance than other traditional approaches in terms of signal-to-noise ratio, power consumption, and weight requirements.

Exposure versus internal dose: Respiratory tract deposition modeling of inhaled asbestos fibers in rats and humans (Presentation Poster)

EPA Science Inventory

Exposure to asbestos is associated with respiratory diseases, including asbestosis, lung cancer and mesothelioma. Internal fiber dose depends on fiber inhalability and orientation, fiber density, length and width, and various deposition mechanisms (DM). Species-specific param...

The Audacity of Fiber-Wireless (FiWi) Networks

NASA Astrophysics Data System (ADS)

Maier, Martin; Ghazisaidi, Navid; Reisslein, Martin

A plethora of enabling optical and wireless technologies have been emerging that can be used to build future-proof bimodal fiber-wireless (FiWi) broadband access networks. After overviewing key enabling radio-over-fiber (RoF) and radio-and-fiber (R&F) technologies and briefly surveying the state of the art of FiWi networks, we introduce an Ethernet-based access-metro FiWi network, called SuperMAN, that integrates next-generation WiFi and WiMAX networks with WDM-enhanced EPON and RPR networks. Throughout the paper we pay close attention to the technical challenges and opportunities of FiWi networks, but also elaborate on their societal benefits and potential to shift the current research focus from optical-wireless networking to the exploitation of personal and in-home computing facilities to create new unforeseen services and applications as we are about to enter the Petabyte age.

On the strength of random fiber networks

NASA Astrophysics Data System (ADS)

Deogekar, S.; Picu, R. C.

2018-07-01

Damage accumulation and failure in random fiber networks is of importance in a variety of applications, from design of synthetic materials, such as paper and non-wovens, to accidental tearing of biological tissues. In this work we study these processes using three-dimensional models of athermal fiber networks, focusing attention on the modes of failure and on the relationship between network strength and network structural parameters. We consider network failure at small and large strains associated with the rupture of inter-fiber bonds. It is observed that the strength increases linearly with the network volume fraction and with the bond strength, while the stretch at peak stress is inversely related to these two parameters. A small fraction of the bonds rupture before peak stress and this fraction increases with increasing failure stretch. Rendering the bond strength stochastic causes a reduction of the network strength. However, heterogeneity retards damage localization and increases the stretch at peak stress, therefore promoting ductility.

Gender differences in the structural connectome of the teenage brain revealed by generalized q-sampling MRI.

PubMed

Tyan, Yeu-Sheng; Liao, Jan-Ray; Shen, Chao-Yu; Lin, Yu-Chieh; Weng, Jun-Cheng

2017-01-01

The question of whether there are biological differences between male and female brains is a fraught one, and political positions and prior expectations seem to have a strong influence on the interpretation of scientific data in this field. This question is relevant to issues of gender differences in the prevalence of psychiatric conditions, including autism, attention deficit hyperactivity disorder (ADHD), Tourette's syndrome, schizophrenia, dyslexia, depression, and eating disorders. Understanding how gender influences vulnerability to these conditions is significant. Diffusion magnetic resonance imaging (dMRI) provides a non-invasive method to investigate brain microstructure and the integrity of anatomical connectivity. Generalized q-sampling imaging (GQI) has been proposed to characterize complicated fiber patterns and distinguish fiber orientations, providing an opportunity for more accurate, higher-order descriptions through the water diffusion process. Therefore, we aimed to investigate differences in the brain's structural network between teenage males and females using GQI. This study included 59 (i.e., 33 males and 26 females) age- and education-matched subjects (age range: 13 to 14 years). The structural connectome was obtained by graph theoretical and network-based statistical (NBS) analyses. Our findings show that teenage male brains exhibit better intrahemispheric communication, and teenage female brains exhibit better interhemispheric communication. Our results also suggest that the network organization of teenage male brains is more local, more segregated, and more similar to small-world networks than teenage female brains. We conclude that the use of an MRI study with a GQI-based structural connectomic approach like ours presents novel insights into network-based systems of the brain and provides a new piece of the puzzle regarding gender differences.

Dynamics of Mechanical Signal Transmission through Prestressed Stress Fibers

PubMed Central

Hwang, Yongyun; Barakat, Abdul I.

2012-01-01

Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance mechanotransduction in cells; however, a quantitative understanding of the dynamics of this transmission and the physical factors governing it remains lacking. Two key features of the actin cytoskeleton are its viscoelastic nature and the presence of prestress due to actomyosin motor activity. We develop a model of mechanical signal transmission through prestressed viscoelastic actin stress fibers that directly connect the cell surface to the nucleus. The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. To elucidate the physical parameters that govern mechanical signal transmission, we initially focus on the highly simplified case of a single stress fiber. The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. Conversely, signal transmission for axial motion is mediated uniquely by elasticity due to the absence of a prestress restoring force. Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. Only transverse motion yields the rapid and long-distance mechanical signal transmission dynamics observed experimentally. For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission and allows temporally oscillatory signals in the physiological frequency range to travel a long distance without significant decay due to material viscosity and/or cytosolic drag. PMID:22514731

Development of Low Noise-Broadband Raman Amplification Systems Based on Photonic Crystal Fibers for High Capacity DWDM Networks

NASA Astrophysics Data System (ADS)

Elgamri, Abdelghafor

The increased demand from IP traffic, video application and cell backhaul has placed fiber routes under severe stains. The high demands for large bandwidth from enormous numbers from cell sites on a network made the capacity of yesterday's networks not adequate for today's bandwidth demand. Carries considered Dense Wavelength Division Multiplexing (DWDM) network to overcome this issue. Recently, there has been growing interest in fiber Raman amplifiers due to their capability to upgrade the wavelength-division-multiplexing bandwidth, arbitrary gain bandwidth. In addition, photonic crystal fibers have been widely modeled, studied, and fabricated due to their peculiar properties that cannot be achieved with conventional fibers. The focus of this thesis is to develop a low-noise broadband Raman amplification system based on photonic crystal Fiber that can be implemented in high capacity DWDM network successfully. The design a module of photonic crystal fiber Raman amplifier is based on the knowledge of the fiber cross-sectional characteristics i.e. the geometric parameters and the Germania concentration in the dope area. The module allows to study different air-hole dimension and disposition, with or without a central doped area. In addition the design integrates distributed Raman amplifier and nonlinear optical loop mirror to improve the signal to noise ratio and overall gain in large capacity DWDM networks.

Dynamic fracture toughness of cellulose-fiber-reinforced polypropylene : preliminary investigation of microstructural effects

Treesearch

Craig M. Clemons; Daniel F. Caulfield; A. Jeffrey Giacomin

1999-10-01

In this study, the microstructure of injection-molded polypropylene reinforced with cellulose fiber was investigated. Scanning electron microscopy of the fracture surfaces and X-ray diffraction were used to investigate fiber orientation. The polypropylene matrix was removed by solvent extraction, and the lengths of the residual fibers were optically determined. Fiber...

Optical fiber cabling technologies for flexible access network

NASA Astrophysics Data System (ADS)

Tanji, Hisashi

2008-07-01

Fiber-to-the-home (FTTH) outside plant infrastructure should be so designed and constructed as to flexibly deal with increasing subscribers and system evolution to be expected in the future, taking minimization of total cost (CAPEX and OPEX) into consideration. With this in mind, fiber access architectures are reviewed and key technologies on optical fiber and cable for supporting flexible access network are presented. Low loss over wide wavelength (low water peak) and bend-insensitive single mode fiber is a future proof solution. Enhanced separable ribbon facilitates mid-span access to individual fibers in a cable installed, improving fiber utilizing efficiency and flexibility of distribution design. It also contributes to an excellent low PMD characteristic which could be required for video RF overlay system or high capacity long reach metro-access convergence network in the future. Bend-insensitive fiber based cabling technique including field installable connector greatly improves fiber/cable handling in installation and maintenance work.

Population gratings in saturable optical fibers with randomly oriented rare-earth ions

NASA Astrophysics Data System (ADS)

Stepanov, S.; Martinez, L. M.; Hernandez, E. H.; Agruzov, P.; Shamray, A.

2015-07-01

Formation of the dynamic population gratings in optical fibers with randomly oriented rare-earth ions is analyzed with a special interest to the grating component for readout with the orthogonal light polarization. It is shown that as compared with a simple model case of the collinearly oriented dipole-like centers their random orientation leads to approximately 2-times growth of the effective saturation power P sat when it is estimated from the incident power dependence of the fiber absorption or from that of the fluorescence intensity. An optimal incident power, for which the maximum of the dynamic population grating amplitude for collinear light polarization is observed, also follows this change in P sat, while formation of the grating for orthogonal polarization needs essentially higher light power. The reduced anisotropy of the active centers, which is in charge of the experimentally observed weakening of the polarization hole burning (PHB) and of the fluorescence polarization, compensates in some way the effect of random ion orientation. The ratio between the maximum conventional (i.e. for the interacting waves collinear polarizations) two-wave mixing (TWM) amplitude and the initial not saturable fiber optical density proves to be, however, nearly the same as in the model case of collinearly oriented dipoles. The ratio between the PHB effect and the amplitude of the anisotropic grating, which is responsible for TWM of the orthogonally polarized waves, is also not influenced significantly by the reduced anisotropy of ions.

Mechanical characteristics of low-cost hybrid fiber reinforced polymer.

DOT National Transportation Integrated Search

2014-07-01

This report deals with the experimental investigation of using large deformable FRP, 45 oriented fibers, in concrete-filled fiber : tubes (CFFT) under axial cyclic compressive loading. In addition, this report presents finite element modeling (F...

The influence of fiber orientation on the equilibrium properties of neutral and charged biphasic tissues.

PubMed

Nagel, Thomas; Kelly, Daniel J

2010-11-01

Constitutive models facilitate investigation into load bearing mechanisms of biological tissues and may aid attempts to engineer tissue replacements. In soft tissue models, a commonly made assumption is that collagen fibers can only bear tensile loads. Previous computational studies have demonstrated that radially aligned fibers stiffen a material in unconfined compression most by limiting lateral expansion while vertically aligned fibers buckle under the compressive loads. In this short communication, we show that in conjunction with swelling, these intuitive statements can be violated at small strains. Under such conditions, a tissue with fibers aligned parallel to the direction of load initially provides the greatest resistance to compression. The results are further put into the context of a Benninghoff architecture for articular cartilage. The predictions of this computational study demonstrate the effects of varying fiber orientations and an initial tare strain on the apparent material parameters obtained from unconfined compression tests of charged tissues.

Experimental and analytical investigation of the fracture processes of boron/aluminum laminates containing notches

NASA Technical Reports Server (NTRS)

Johnson, W. S.; Bigelow, C. A.; Bahei-El-din, Y. A.

1983-01-01

Experimental results for five laminate orientations of boron/aluminum composites containing either circular holes or crack-like slits are presented. Specimen stress-strain behavior, stress at first fiber failure, and ultimate strength were determined. Radiographs were used to monitor the fracture process. The specimens were analyzed with a three-dimensional elastic-elastic finite-element model. The first fiber failures in notched specimens with laminate orientation occurred at or very near the specimen ultimate strength. For notched unidirectional specimens, the first fiber failure occurred at approximately one-half of the specimen ultimate strength. Acoustic emission events correlated with fiber breaks in unidirectional composites, but did not for other laminates. Circular holes and crack-like slits of the same characteristic length were found to produce approximately the same strength reduction. The predicted stress-strain responses and stress at first fiber failure compared very well with test data for laminates containing 0 deg fibers.

More on the elongational viscosity of an oriented fiber assembly

NASA Technical Reports Server (NTRS)

Pipes, R. Byron, Jr.; Beaussart, A. J.; Okine, R. K.

1990-01-01

The effective elongational viscosity for an oriented fiber assembly of discontinuous fibers suspended in a viscous matrix fluid is developed for a fiber array with variable overlap length of both symmetric and asymmetric geometries. Further, the relation is developed for a power-law matrix fluid with finite yield stress. The developed relations for a Newtonian fluid reveal that the influence of overlap length upon elongational viscosity may be expressed as a polynomial of second order. The results for symmetric and asymmetric geometries are shown to be equivalent. Finally, for the power-law fluid the influence of fiber aspect ratio on elongational viscosity was shown to be of order m + 1, where m is greater than 0 and less than 1, as compared to 2 for the Newtonian fluid, while the effective yield stress was found to be proportional to the fiber aspect ratio and volume fraction.

Angle of Arrival Detection Through Artificial Neural Network Analysis of Optical Fiber Intensity Patterns

DTIC Science & Technology

1990-12-01

ARTIFICIAL NEURAL NETWORK ANALYSIS OF OPTICAL FIBER INTENSITY PATTERNS THESIS Scott Thomas Captain, USAF AFIT/GE/ENG/90D-62 DTIC...ELECTE ao • JAN08 1991 Approved for public release; distribution unlimited. AFIT/GE/ENG/90D-62 ANGLE OF ARRIVAL DETECTION THROUGH ARTIFICIAL NEURAL NETWORK ANALYSIS... ARTIFICIAL NEURAL NETWORK ANALYSIS OF OPTICAL FIBER INTENSITY PATTERNS L Introduction The optical sensors of United States Air Force reconnaissance

Mass Transfer and Rheology of Fiber Suspensions

NASA Astrophysics Data System (ADS)

Wang, Jianghui

Rheological and mass transfer properties of non-Brownian fiber suspensions are affected by fiber characteristics, fiber interactions, and processing conditions. In this thesis we develop several simulation methods to study the dynamics of single fibers in simple shear flow, as well as the rheology and mass transfer of fiber suspensions. Isolated, rigid, neutrally-buoyant, non-Brownian, slightly curved, nonchiral fibers in simple shear flow of an incompressible Newtonian fluid at low Reynolds number can drift steadily in the gradient direction without external forces or torques. The average drift velocity and direction depend on the fiber aspect ratio, curvature and initial orientation. The drift results from the coupling of rotational and translational dynamics, and the combined effects of flipping, scooping, and spinning motions of the fiber. Irreversible fiber collisions in the suspensions cause shear-induced diffusion. The shear-induced self-diffusivity of dilute suspensions of fibers increases with increasing concentration and increasing static friction between contacts. The diffusivities in both the gradient and vorticity directions are larger for suspensions of curved fibers than for suspensions of straight fibers. For suspensions of curved fibers, significant enhancements in the diffusivity in the gradient direction are attributed to fiber drift in the gradient direction. The shear-induced self-diffusivity of concentrated suspensions of fibers increases with increasing concentration before fiber networks or flocs are formed, after which the diffusivity decreases with increasing concentration. The diffusivity increases with increasing fiber equilibrium bending angle, effective stiffness, coefficient of static friction, and rate of collisions. The specific viscosity of fiber suspensions increases with increasing fiber curvature, friction coefficient between mechanical contacts, and solids concentration. The specific viscosity increases linearly with concentration in the dilute regime, and increases with the cube of the concentration in the semi-dilute regime. Concentrated fiber suspensions are highly viscous, shear thinning, and exhibit significant yield stresses and normal stress differences. Yield stresses scale with volume concentration and fiber aspect ratio in the same way as that observed in experiments. The first normal stress difference increases linearly with shear rate. The shear-induced diffusivity increases linearly with the derivative of the particle contribution to stress for dilute suspensions with respective to concentration. This correlation between rheology and shear-induced diffusion makes it possible to predict diffusivity from easily measured rheological properties.

Development of generalized 3-D braiding machines for composite preforms

NASA Technical Reports Server (NTRS)

Huey, Cecil O., Jr.; Farley, Gary L.

1993-01-01

The operating principles of two prototype braiding machines for the production of generalized braid patterns are described. Both processes afford previously unachievable control of the interlacing of fibers within a textile structure that make them especially amenable to the fabrication of textile preforms for composite materials. They enable independent control of the motion of the individual fibers being woven, thereby enabling the greatest possible freedom in controlling fiber orientation within a structure. This freedom enables the designer to prescribe local fiber orientation to better optimize material performance. The processes have been implemented on a very small scale but at a level that demonstrates their practicality and the soundness of the principles governing their operation.

Reproducibility Analysis of Diffusion Tensor Indices and Fiber Architecture of Human Calf Muscles in vivo at 1.5 Tesla in Neutral and Plantarflexed Ankle Positions at Rest

PubMed Central

Sinha, Shantanu; Sinha, Usha

2011-01-01

Purpose To investigate the reproducibility of diffusion tensor imaging (DTI) derived indices and fiber architecture of calf muscles at 1.5 Tesla, to establish an imaging based method to confirm ankle position, and to compare fiber architecture at different ankle positions. Materials and Methods Six subjects were imaged at 1.5T with the foot in neutral and plantarflexed positions. DTI indices were calculated in four muscle compartments (medial and lateral gastrocnemius (MG, LG), superficial and deep anterior tibialis (AT-S, AT-D). Two subjects were scanned on three days to calculate the coefficient of variability (CV) and the repeatability coefficient (RC). Results DTI indices were close to the values obtained in earlier 3T and 1.5 T studies. FA decreased significantly in the MG and increased significantly in the AT-S and AT-D compartments while fiber orientation with respect to the magnet Z-axis increased significantly in the MG and decreased significantly in the AT-S compartment with plantarflexion. The CV and RC for the DTI indices and fiber orientations were comparable to 3T studies. Fiber lengths and orientation angles in the MG matched corresponding measures from ultrasound studies. Conclusion DTI at 1.5 Tesla provides reproducible measures of diffusion indices and fiber architecture of calf muscle at different muscle lengths. PMID:21608064

Joint Multi-Fiber NODDI Parameter Estimation and Tractography Using the Unscented Information Filter

PubMed Central

Reddy, Chinthala P.; Rathi, Yogesh

2016-01-01

Tracing white matter fiber bundles is an integral part of analyzing brain connectivity. An accurate estimate of the underlying tissue parameters is also paramount in several neuroscience applications. In this work, we propose to use a joint fiber model estimation and tractography algorithm that uses the NODDI (neurite orientation dispersion diffusion imaging) model to estimate fiber orientation dispersion consistently and smoothly along the fiber tracts along with estimating the intracellular and extracellular volume fractions from the diffusion signal. While the NODDI model has been used in earlier works to estimate the microstructural parameters at each voxel independently, for the first time, we propose to integrate it into a tractography framework. We extend this framework to estimate the NODDI parameters for two crossing fibers, which is imperative to trace fiber bundles through crossings as well as to estimate the microstructural parameters for each fiber bundle separately. We propose to use the unscented information filter (UIF) to accurately estimate the model parameters and perform tractography. The proposed approach has significant computational performance improvements as well as numerical robustness over the unscented Kalman filter (UKF). Our method not only estimates the confidence in the estimated parameters via the covariance matrix, but also provides the Fisher-information matrix of the state variables (model parameters), which can be quite useful to measure model complexity. Results from in-vivo human brain data sets demonstrate the ability of our algorithm to trace through crossing fiber regions, while estimating orientation dispersion and other biophysical model parameters in a consistent manner along the tracts. PMID:27147956

Joint Multi-Fiber NODDI Parameter Estimation and Tractography Using the Unscented Information Filter.

PubMed

Reddy, Chinthala P; Rathi, Yogesh

2016-01-01

Tracing white matter fiber bundles is an integral part of analyzing brain connectivity. An accurate estimate of the underlying tissue parameters is also paramount in several neuroscience applications. In this work, we propose to use a joint fiber model estimation and tractography algorithm that uses the NODDI (neurite orientation dispersion diffusion imaging) model to estimate fiber orientation dispersion consistently and smoothly along the fiber tracts along with estimating the intracellular and extracellular volume fractions from the diffusion signal. While the NODDI model has been used in earlier works to estimate the microstructural parameters at each voxel independently, for the first time, we propose to integrate it into a tractography framework. We extend this framework to estimate the NODDI parameters for two crossing fibers, which is imperative to trace fiber bundles through crossings as well as to estimate the microstructural parameters for each fiber bundle separately. We propose to use the unscented information filter (UIF) to accurately estimate the model parameters and perform tractography. The proposed approach has significant computational performance improvements as well as numerical robustness over the unscented Kalman filter (UKF). Our method not only estimates the confidence in the estimated parameters via the covariance matrix, but also provides the Fisher-information matrix of the state variables (model parameters), which can be quite useful to measure model complexity. Results from in-vivo human brain data sets demonstrate the ability of our algorithm to trace through crossing fiber regions, while estimating orientation dispersion and other biophysical model parameters in a consistent manner along the tracts.

Strain and in-plane orientation effects on the ferroelectricity of (111)-oriented tetragonal Pb(Zr0.35Ti0.65)O3 thin films prepared by metal organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kuwabara, Hiroki; Menou, Nicolas; Funakubo, Hiroshi

2007-05-01

The growth and characterization of epitaxial (111)-oriented Pb(Zr0.35Ti0.65)O3 films deposited by metal organic chemical vapor deposition on (100)-oriented silicon substrates [(111)SrRuO3‖(111)Pt ‖(100)yttria-stabilizedzirconia‖(100)Si] are reported. The orientation, microstructure, and electric properties of these films are compared to those of fiber-textured highly (111)-oriented lead zirconate titanate (PZT) films deposited on (111)SrRuO3/(111)Pt/TiOx/SiO2/(100)Si substrates and epitaxial (111)-oriented PZT films deposited on (111)SrRuO3‖(111)SrTiO3 substrates. The ferroelectric properties of these films are not drastically influenced by the in-plane orientation of the film and by the strain state imposed by the underlying substrate. These results support the use of fiber-textured highly (111)-oriented films in highly stable ferroelectric capacitors.

Specificity of V1-V2 Orientation Networks in the Primate Visual Cortex

PubMed Central

Roe, Anna W.; Ts'o, Daniel Y.

2015-01-01

The computation of texture and shape involves integration of features of various orientations. Orientation networks within V1 tend to involve cells which share similar orientation selectivity. However, emergent properties in V2 require the integration of multiple orientations. We now show that, unlike interactions within V1, V1-V2 orientation interactions are much less synchronized and are not necessarily orientation dependent. We find V1-V2 orientation networks are of two types: a more tightly synchronized, orientation-preserving network and a less synchronized orientation-diverse network. We suggest that such diversity of V1-V2 interactions underlies the spatial and functional integration required for computation of higher order contour and shape in V2. PMID:26314798

Structure and mechanics of aegagropilae fiber network.

PubMed

Verhille, Gautier; Moulinet, Sébastien; Vandenberghe, Nicolas; Adda-Bedia, Mokhtar; Le Gal, Patrice

2017-05-02

Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal behavior of these complex structures depends on both the individual response of the constituent fibers and the density and degree of entanglement of the network. A question of paramount importance is how to control the formation of a given fiber network to optimize a desired function. The study of fiber clustering of natural flocs could be useful for improving fabrication processes, such as in the paper and textile industries. Here, we use the example of aegagropilae that are the remains of a seagrass ( Posidonia oceanica ) found on Mediterranean beaches. First, we characterize different aspects of their structure and mechanical response, and second, we draw conclusions on their formation process. We show that these natural aggregates are formed in open sea by random aggregation and compaction of fibers held together by friction forces. Although formed in a natural environment, thus under relatively unconstrained conditions, the geometrical and mechanical properties of the resulting fiber aggregates are quite robust. This study opens perspectives for manufacturing complex fiber network materials.

Effects of Crystal Orientation on Cellulose Nanocrystals−Cellulose Acetate Nanocomposite Fibers Prepared by Dry Spinning

Treesearch

Si Chen; Greg Schueneman; R. Byron Pipes; Jeffrey Youngblood; Robert J. Moon

2014-01-01

This work presents the development of dry spun cellulose acetate (CA) fibers using cellulose nanocrystals (CNCs) as reinforcements. Increasing amounts of CNCs were dispersed into CA fibers in efforts to improve the tensile strength and elastic modulus of the fiber. A systematic characterization of dispersion of CNCs in the polymer fiber and their effect on the...

Molecular orientation in aligned electrospun polyimide nanofibers by polarized FT-IR spectroscopy.

PubMed

Yang, Haoqi; Jiang, Shaohua; Fang, Hong; Hu, Xiaowu; Duan, Gaigai; Hou, Haoqing

2018-07-05

Quantitative explanation on the improved mechanical properties of aligned electrospun polyimide (PI) nanofibers as the increased imidization temperatures is highly required. In this work, polarized FT-IR spectroscopy is applied to solve this problem. Based on the polarized FT-IR spectroscopy and the molecular model in the fibers, the length of the repeat unit of PI molecule, the angle between the fiber axis and the symmetric stretching direction of carbonyl group on the imide ring, and the angle between the PI molecular axis and fiber axis are all investigated. The Mark-Howink equation is used to calculate the number-average molar mass of PI molecules. The orientation states of PI molecules in the electrospun nanofibers are studied from the number-average molar mass of PI molecules and the average fiber diameter. Quantitative analysis of the orientation factor of PI molecules in the electrospun nanofibers is performed by polarized FT-IR spectroscopy. Copyright © 2018 Elsevier B.V. All rights reserved.

Orientation and length of mammalian skeletal myocytes in response to a unidirectional stretch

NASA Technical Reports Server (NTRS)

Collinsworth, A. M.; Torgan, C. E.; Nagda, S. N.; Rajalingam, R. J.; Kraus, W. E.; Truskey, G. A.

2000-01-01

Effects of mechanical forces exerted on mammalian skeletal muscle cells during development were studied using an in vitro model to unidirectionally stretch cultured C2C12 cells grown on silastic membrane. Previous models to date have not studied these responses of the mammalian system specifically. The silastic membrane upon which these cells were grown exhibited linear strain behavior over the range of 3.6-14.6% strain, with a Poisson's ratio of approximately 0.5. To mimic murine in utero long bone growth, cell substrates were stretched at an average strain rate of 2.36%/day for 4 days or 1.77%/day for 6 days with an overall membrane strain of 9.5% and 10.6%, respectively. Both control and stretched fibers stained positively for the contractile protein, alpha-actinin, demonstrating muscle fiber development. An effect of stretch on orientation and length of myofibers was observed. At both strain rates, stretched fibers aligned at a smaller angle relative to the direction of stretch and were significantly longer compared to randomly oriented control fibers. There was no effect of duration of stretch on orientation or length, suggesting the cellular responses are independent of strain rate for the range tested. These results demonstrate that, under conditions simulating mammalian long bone growth, cultured myocytes respond to mechanical forces by lengthening and orienting along the direction of stretch.

New CATV fiber-to-the-subscriber architectures

NASA Astrophysics Data System (ADS)

Kim, Gary

1991-01-01

Although the cable television industry has seriously proposed the widespread use of optical fiber technology as the foundation of its networks only since 1988 an important financial watershed already has been reached. Based on stunningly rapid AM technology developments and new research by industry engineers the CATV industry has already reached the point where building new optical trunk is cheaper than building conventional coaxial cable plant. Although as recently as 1988 it might have seemed preposterous to suggest that the financial crossover point between optical media and copper media would soon be reached that indeed has occurred. Using a topology dubbed the " fiber trunk and feeder engineers at American Television Communications the second-largest U. S. CATV operator have demonstrated that it is currently feasible to build new optical fiber trunking networks at costs equal to or less than conventional 450-MHz coaxial cable plant. Installation of the first such network already is underway and it is expected that the significant change in fiber economics will further spur the already-heady pace of fiber introduction in the CATV industry. That in turn will create new types of networks with topologies resembling telephone " star" networks more than conventional " tree-and-branch" systems. The new optically-based networks will be far more reliable more flexible and better adapted to signal switching than conventional CATV networks have been. Although the new networks will be put into place

Optical-Fiber Fluorosensors With Polarized Light Sources

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1995-01-01

Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

PubMed

Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

2013-01-28

We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

Fiber networks amplify active stress

PubMed Central

Ronceray, Pierre; Broedersz, Chase P.

2016-01-01

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. Although these fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. Here we theoretically study force transmission in these networks. We find that collective fiber buckling in the vicinity of a local active unit results in a rectification of stress towards strongly amplified isotropic contraction. This stress amplification is reinforced by the networks’ disordered nature, but saturates for high densities of active units. Our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks and shed light on the role of the network microstructure in shaping active stresses in cells and tissue. PMID:26921325

A hybrid optic-fiber sensor network with the function of self-diagnosis and self-healing

NASA Astrophysics Data System (ADS)

Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Cheng; Zhang, Hongxia

2014-11-01

We develop a hybrid wavelength division multiplexing optical fiber network with distributed fiber-optic sensors and quasi-distributed FBG sensor arrays which detect vibrations, temperatures and strains at the same time. The network has the ability to locate the failure sites automatically designated as self-diagnosis and make protective switching to reestablish sensing service designated as self-healing by cooperative work of software and hardware. The processes above are accomplished by master-slave processors with the help of optical and wireless telemetry signals. All the sensing and optical telemetry signals transmit in the same fiber either working fiber or backup fiber. We take wavelength 1450nm as downstream signal and wavelength 1350nm as upstream signal to control the network in normal circumstances, both signals are sent by a light emitting node of the corresponding processor. There is also a continuous laser wavelength 1310nm sent by each node and received by next node on both working and backup fibers to monitor their healthy states, but it does not carry any message like telemetry signals do. When fibers of two sensor units are completely damaged, the master processor will lose the communication with the node between the damaged ones.However we install RF module in each node to solve the possible problem. Finally, the whole network state is transmitted to host computer by master processor. Operator could know and control the network by human-machine interface if needed.

Diaphragmatic lymphatic vessel behavior during local skeletal muscle contraction.

PubMed

Moriondo, Andrea; Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela

2015-02-01

The mechanism through which the stresses developed in the diaphragmatic tissue during skeletal muscle contraction sustain local lymphatic function was studied in 10 deeply anesthetized, tracheotomized adult Wistar rats whose diaphragm was exposed after thoracotomy. To evaluate the direct effect of skeletal muscle contraction on the hydraulic intraluminal lymphatic pressures (Plymph) and lymphatic vessel geometry, the maximal contraction of diaphragmatic fibers adjacent to a lymphatic vessel was elicited by injection of 9.2 nl of 1 M KCl solution among diaphragmatic fibers while Plymph was recorded through micropuncture and vessel geometry via stereomicroscopy video recording. In lymphatics oriented perpendicularly to the longitudinal axis of muscle fibers and located at <300 μm from KCl injection, vessel diameter at maximal skeletal muscle contraction (Dmc) decreased to 61.3 ± 1.4% of the precontraction value [resting diameter (Drest)]; however, if injection was at >900 μm from the vessel, Dmc enlarged to 131.1 ± 2.3% of Drest. In vessels parallel to muscle fibers, Dmc increased to 122.8 ± 2.9% of Drest. During contraction, Plymph decreased as much as 22.5 ± 2.6 cmH2O in all submesothelial superficial vessels, whereas it increased by 10.7 ± 5.1 cmH2O in deeper vessels running perpendicular to contracting muscle fibers. Hence, the three-dimensional arrangement of the diaphragmatic lymphatic network seems to be finalized to efficiently exploit the stresses exerted by muscle fibers during the contracting inspiratory phase to promote lymph formation in superficial submesothelial lymphatics and its further propulsion in deeper intramuscular vessels. Copyright © 2015 the American Physiological Society.

Free Vibration of Fiber Composite Thin Shells in a Hot Environment

NASA Technical Reports Server (NTRS)

Gotsis, Pascal K.; Guptill, James D.

1995-01-01

Results are presented of parametric studies to assess the effects of various parameters on the free vibration behavior (natural frequencies) of (plus or minus theta)2, angle-ply fiber composite thin shells in a hot environment. These results were obtained by using a three-dimensional finite element structural analysis computer code. The fiber composite shell is assumed to be cylindrical and made from T-300 graphite fibers embedded in an intermediate-modulus high-strength matrix (IMHS). The residual stresses induced into the laminated structure during curing are taken into account. The following parameters are investigated: the length and the thickness of the shell, the fiber orientations, the fiber volume fraction, the temperature profile through the thickness of the laminate and the different ply thicknesses. Results obtained indicate that: the fiber orientations and the length of the laminated shell had significant effect on the natural frequencies. The fiber volume fraction, the laminate thickness and the temperature profile through the shell thickness had a weak effect on the natural frequencies. Finally, the laminates with different ply thicknesses had insignificant influence on the behavior of the vibrated laminated shell.

A strategy for prediction of the elastic properties of epoxy-cellulose nanocrystal-reinforced fiber networks

Treesearch

Johnathan E. Goodsell; Robert J. Moon; Alionso Huizar; R. Byron Pipes

2014-01-01

The reinforcement potential of cellulose nanocrystal (CNC) additions on an idealized 2-dirmensional (2-D) fiber network structure consisting of micron sized fiber elements was investigated. The reinforcement mechanism considered in this study was through the stiffening of the micron sized fiber elements via a CNC-epoxy coating. A hierarchical analytical modeling...

Integrated mechanics for the passive damping of polymer-matrix composites and composite structures

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Chamis, Christos C.

1991-01-01

Some recent developments on integrated damping mechanics for unidirectional composites, laminates, and composite structures are reviewed. Simplified damping micromechanics relate the damping of on-axis and off-axis composites to constituent properties, fiber volume ratio, fiber orientation, temperature, and moisture. Laminate and structural damping mechanics for thin composites are summarized. Discrete layer damping mechanics for thick laminates, including the effects of interlaminar shear damping, are developed and semianalytical predictions of modal damping in thick simply supported specialty composite plates are presented. Applications show the advantages of the unified mechanics, and illustrate the effect of fiber volume ratio, fiber orientation, structural geometry, and temperature on the damping. Additional damping properties for composite plates of various laminations, aspect ratios, fiber content, and temperature illustrate the merits and ranges of applicability of each theory (thin or thick laminates).

Dynamic mechanical analysis of fiber reinforced composites

NASA Technical Reports Server (NTRS)

Reed, K. E.

1979-01-01

Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.

Rigid Amorphous Fraction in PLA Electrospun Fibers

NASA Astrophysics Data System (ADS)

Cebe, Peggy; Ma, Qian; Simona Cozza, Erika; Pyda, Marek; Mao, Bin; Zhu, Yazhe; Monticelli, Orietta

2013-03-01

Electrospun fibers of poly(lactic acid) (PLA) were formed by adopting a high-speed rotating wheel as the counter-electrode. The molecular orientation, crystallization mechanism, and phase structure and transitions of the aligned ES fibers were investigated. Using thermal analysis and wide angle X-ray scattering (WAXS), we evaluated the confinement that exists in as-spun amorphous, and heat-treated semicrystalline, fibers. Differential scanning calorimetry confirmed the existence of a constrained amorphous phase in as-spun aligned fibers, without the presence of crystals or fillers to serve as fixed physical constraints. Using WAXS, for the first time the mesophase fraction, consisting of oriented amorphous PLA chains, was quantitatively characterized in nanofibers. The authors acknowledge support from the National Science Foundation, Polymers Program under grant DMR-0602473. ESC acknowledges a Ph.D. grant supported by Italian Ministry of Education and Scientific Research.

Fiber length and orientation prevent migration in fluid filters

NASA Technical Reports Server (NTRS)

Reiman, P. A.

1966-01-01

Stainless steel fiber web filter resists fiber migration which causes contamination of filtered fluids. This filter is capable of holding five times more particulate matter before arbitrary cutoff pressure drop and shows excellent retention in fuel flow at high rates.

Generation of Spatially Aligned Collagen Fiber Networks through Microtransfer Molding

PubMed Central

Naik, Nisarga; Caves, Jeffrey

2013-01-01

The unique biomechanical properties of native tissue are governed by the organization and composition of integrated collagen and elastin networks. We report an approach for fabricating spatially aligned, fiber-reinforced composites (FRC) with adjustable collagen fiber dimensions, layouts, and distribution within an elastin-like protein matrix yielding a biocomposite with controllable mechanical responses. Microtransfer molding is employed for the fabrication of hollow and solid collagen fibers with straight or crimped fiber geometries. Collagen fibers (width: 2 – 50 μm, thickness: 300 nm – 3 μm) exhibit a Young’s modulus of 126 ± 61 MPa and an ultimate tensile strength (UTS) of 7 ± 3.2 MPa. As fiber networks within composite structures, straight fiber layouts display orthotropic responses with Young’s modulus ranging from 0.95 ± 0.35 to 10.4 ± 0.5 MPa and tensile strength from 0.22 ± 0.08 to 0.87 ± 0.5 MPa with increasing fraction of collagen fibers (1–10% v/v). In contrast, composites based on crimped fiber layouts exhibit strain-dependent stiffness with an increase in Young’s modulus from 0.7 ± 0.14 MPa to 3.15 ± 0.49 MPa, at a specific transition strain. Through controlling the microstructure of engineered collagen fiber networks, a facile means has been established to control macroscale mechanical responses of composite protein-based materials. PMID:24039146

Human Fetal Brain Connectome: Structural Network Development from Middle Fetal Stage to Birth

PubMed Central

Song, Limei; Mishra, Virendra; Ouyang, Minhui; Peng, Qinmu; Slinger, Michelle; Liu, Shuwei; Huang, Hao

2017-01-01

Complicated molecular and cellular processes take place in a spatiotemporally heterogeneous and precisely regulated pattern in the human fetal brain, yielding not only dramatic morphological and microstructural changes, but also macroscale connectomic transitions. As the underlying substrate of the fetal brain structural network, both dynamic neuronal migration pathways and rapid developing fetal white matter (WM) fibers could fundamentally reshape early fetal brain connectome. Quantifying structural connectome development can not only shed light on the brain reconfiguration in this critical yet rarely studied developmental period, but also reveal alterations of the connectome under neuropathological conditions. However, transition of the structural connectome from the mid-fetal stage to birth is not yet known. The contribution of different types of neural fibers to the structural network in the mid-fetal brain is not known, either. In this study, diffusion tensor magnetic resonance imaging (DT-MRI or DTI) of 10 fetal brain specimens at the age of 20 postmenstrual weeks (PMW), 12 in vivo brains at 35 PMW, and 12 in vivo brains at term (40 PMW) were acquired. The structural connectome of each brain was established with evenly parcellated cortical regions as network nodes and traced fiber pathways based on DTI tractography as network edges. Two groups of fibers were categorized based on the fiber terminal locations in the cerebral wall in the 20 PMW fetal brains. We found that fetal brain networks become stronger and more efficient during 20–40 PMW. Furthermore, network strength and global efficiency increase more rapidly during 20–35 PMW than during 35–40 PMW. Visualization of the whole brain fiber distribution by the lengths suggested that the network reconfiguration in this developmental period could be associated with a significant increase of major long association WM fibers. In addition, non-WM neural fibers could be a major contributor to the structural network configuration at 20 PMW and small-world network organization could exist as early as 20 PMW. These findings offer a preliminary record of the fetal brain structural connectome maturation from the middle fetal stage to birth and reveal the critical role of non-WM neural fibers in structural network configuration in the middle fetal stage. PMID:29081731

Scalable Optical-Fiber Communication Networks

NASA Technical Reports Server (NTRS)

Chow, Edward T.; Peterson, John C.

1993-01-01

Scalable arbitrary fiber extension network (SAFEnet) is conceptual fiber-optic communication network passing digital signals among variety of computers and input/output devices at rates from 200 Mb/s to more than 100 Gb/s. Intended for use with very-high-speed computers and other data-processing and communication systems in which message-passing delays must be kept short. Inherent flexibility makes it possible to match performance of network to computers by optimizing configuration of interconnections. In addition, interconnections made redundant to provide tolerance to faults.

Characterizing the Collagen Fiber Orientation in Pericardial Leaflets Under Mechanical Loading Conditions

PubMed Central

Alavi, S. Hamed; Ruiz, Victor; Krasieva, Tatiana; Botvinick, Elliot L.; Kheradvar, Arash

2014-01-01

When implanted inside the body, bioprosthetic heart valve leaflets experience a variety of cyclic mechanical stresses such as shear stress due to blood flow when the valve is open, flexural stress due to cyclic opening and closure of the valve, and tensile stress when the valve is closed. These types of stress lead to a variety of failure modes. In either a natural valve leaflet or a processed pericardial tissue leaflet, collagen fibers reinforce the tissue and provide structural integrity such that the very thin leaflet can stand enormous loads related to cyclic pressure changes. The mechanical response of the leaflet tissue greatly depends on collagen fiber concentration, characteristics, and orientation. Thus, understating the microstructure of pericardial tissue and its response to dynamic loading is crucial for the development of more durable heart valve, and computational models to predict heart valves’ behavior. In this work, we have characterized the 3D collagen fiber arrangement of bovine pericardial tissue leaflets in response to a variety of different loading conditions under Second-Harmonic Generation Microscopy. This real-time visualization method assists in better understanding of the effect of cyclic load on collagen fiber orientation in time and space. PMID:23180029

Laser diode fiber optic apparatus for acupuncture treatment by the Oriental method

NASA Astrophysics Data System (ADS)

Pham, Van Hoi; Phung, Huu A.; Bui, Huy; Hoang, Cao D.; Vu, Duc T.; Tran, Minh T.; Nguyen, Minh H.

1998-08-01

The laser acupuncture equipment using laser diodes of 850, 1300 nm and optical fibers as light needles is presented. The double-frequency modulation of laser beam gives the high efficiency treatment of the low-power laser therapy by the oriental acupuncture method. The laser spot from optical fiber of 50 microns is suitable for the irradiation into special points on body or auricular by the acupuncture treatment schema. The laser intensity in pulse regime of 5 - 40 W/cm2 and irradiation time of 5 - 15 minutes are optimum for treatment of neurosis symptoms and pain-relieving.

Fiber-Optic Distribution Of Pulsed Power To Multiple Sensors

NASA Technical Reports Server (NTRS)

Kirkham, Harold

1996-01-01

Optoelectronic systems designed according to time-sharing scheme distribute optical power to multiple integrated-circuit-based sensors in fiber-optic networks. Networks combine flexibility of electronic sensing circuits with advantage of electrical isolation afforded by use of optical fibers instead of electrical conductors to transmit both signals and power. Fiber optics resist corrosion and immune to electromagnetic interference. Sensor networks of this type useful in variety of applications; for example, in monitoring strains in aircraft, buildings, and bridges, and in monitoring and controlling shapes of flexible structures.

Enrichment of light hydrocarbon mixture

DOEpatents

Yang, Dali [Los Alamos, NM; Devlin, David [Santa Fe, NM; Barbero, Robert S [Santa Cruz, NM; Carrera, Martin E [Naperville, IL; Colling, Craig W [Warrenville, IL

2011-11-29

Light hydrocarbon enrichment is accomplished using a vertically oriented distillation column having a plurality of vertically oriented, nonselective micro/mesoporous hollow fibers. Vapor having, for example, both propylene and propane is sent upward through the distillation column in between the hollow fibers. Vapor exits neat the top of the column and is condensed to form a liquid phase that is directed back downward through the lumen of the hollow fibers. As vapor continues to ascend and liquid continues to countercurrently descend, the liquid at the bottom of the column becomes enriched in a higher boiling point, light hydrocarbon (propane, for example) and the vapor at the top becomes enriched in a lower boiling point light hydrocarbon (propylene, for example). The hollow fiber becomes wetted with liquid during the process.

Enrichment of light hydrocarbon mixture

DOEpatents

Yang,; Dali, [Los Alamos, NM; Devlin, David [Santa Fe, NM; Barbero, Robert S [Santa Cruz, NM; Carrera, Martin E [Naperville, IL; Colling, Craig W [Warrenville, IL

2010-08-10

Light hydrocarbon enrichment is accomplished using a vertically oriented distillation column having a plurality of vertically oriented, nonselective micro/mesoporous hollow fibers. Vapor having, for example, both propylene and propane is sent upward through the distillation column in between the hollow fibers. Vapor exits neat the top of the column and is condensed to form a liquid phase that is directed back downward through the lumen of the hollow fibers. As vapor continues to ascend and liquid continues to countercurrently descend, the liquid at the bottom of the column becomes enriched in a higher boiling point, light hydrocarbon (propane, for example) and the vapor at the top becomes enriched in a lower boiling point light hydrocarbon (propylene, for example). The hollow fiber becomes wetted with liquid during the process.

Improved passive optical network architectures to support local area network emulation and protection

NASA Astrophysics Data System (ADS)

Wong, Elaine; Nadarajah, Nishaanthan; Chae, Chang-Joon; Nirmalathas, Ampalavanapillai; Attygalle, Sanjeewa M.

2006-01-01

We describe two optical layer schemes which simultaneously facilitate local area network emulation and automatic protection switching against distribution fiber breaks in passive optical networks. One scheme employs a narrowband fiber Bragg grating placed close to the star coupler in the feeder fiber of the passive optical network, while the other uses an additional short length distribution fiber from the star coupler to each customer for the redirection of the customer traffic. Both schemes use RF subcarrier multiplexed transmission for intercommunication between customers in conjunction with upstream access to the central office at baseband. Failure detection and automatic protection switching are performed independently by each optical network unit that is located at the customer premises in a distributed manner. The restoration of traffic transported between the central office and an optical network unit in the event of the distribution fiber break is performed by interconnecting adjacent optical network units and carrying out signal transmissions via an independent but interconnected optical network unit. Such a protection mechanism enables multiple adjacent optical network units to be simultaneously protected by a single optical network unit utilizing its maximum available bandwidth. We experimentally verify the feasibility of both schemes with 1.25 Gb/s upstream baseband transmission to the central office and 155 Mb/s local area network data transmission on a RF subcarrier frequency. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme.

Innovative design of composite structures: Use of curvilinear fiber format to improve structural efficiency

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Charette, R. F.

1987-01-01

To increase the effectiveness and efficiency of fiber-reinforced materials, the use of fibers in a curvilinear rather than the traditional straightline format is explored. The capacity of a laminated square plate with a central circular hole loaded in tension is investigated. The orientation of the fibers is chosen so that the fibers in a particular layer are aligned with the principle stress directions in that layer. Finite elements and an iteration scheme are used to find the fiber orientation. A noninteracting maximum strain criterion is used to predict load capacity. The load capacities of several plates with different curvilinear fibers format are compared with the capacities of more conventional straightline format designs. It is found that the most practical curvilinear design sandwiches a group of fibers in a curvilinear format between a pair of +/-45 degree layers. This design has a 60% greater load capacity than a conventional quasi-isotropic design with the same number of layers. The +/-45 degree layers are necessary to prevent matrix cracking in the curvilinear layers due to stresses perpendicular to the fibers in those layers. Greater efficiencies are achievable with composite structures than now realized.

Dark Fiber and Distributed Acoustic Sensing: Applications to Monitoring Seismicity and Near-Surface Properties

NASA Astrophysics Data System (ADS)

Ajo Franklin, J. B.; Lindsey, N.; Dou, S.; Freifeld, B. M.; Daley, T. M.; Tracy, C.; Monga, I.

2017-12-01

"Dark Fiber" refers to the large number of fiber-optic lines installed for telecommunication purposes but not currently utilized. With the advent of distributed acoustic sensing (DAS), these unused fibers have the potential to become a seismic sensing network with unparalleled spatial extent and density with applications to monitoring both natural seismicity as well as near-surface soil properties. While the utility of DAS for seismic monitoring has now been conclusively shown on built-for-purpose networks, dark fiber deployments have been challenged by the heterogeneity of fiber installation procedures in telecommunication as well as access limitations. However, the potential of telecom networks to augment existing broadband monitoring stations provides a strong incentive to explore their utilization. We present preliminary results demonstrating the application of DAS to seismic monitoring on a 20 km run of "dark" telecommunications fiber between West Sacramento, CA and Woodland CA, part of the Dark Fiber Testbed maintained by the DOE's ESnet user facility. We show a small catalog of local and regional earthquakes detected by the array and evaluate fiber coupling by using variations in recorded frequency content. Considering the low density of broadband stations across much of the Sacramento Basin, such DAS recordings could provide a crucial data source to constrain small-magnitude local events. We also demonstrate the application of ambient noise interferometry using DAS-recorded waveforms to estimate soil properties under selected sections of the dark fiber transect; the success of this test suggests that the network could be utilized for environmental monitoring at the basin scale. The combination of these two examples demonstrates the exciting potential for combining DAS with ubiquitous dark fiber to greatly extend the reach of existing seismic monitoring networks.

Latency causes and reduction in optical metro networks

NASA Astrophysics Data System (ADS)

Bobrovs, Vjaceslavs; Spolitis, Sandis; Ivanovs, Girts

2013-12-01

The dramatic growth of transmitted information in fiber optical networks is leading to a concern about the network latency for high-speed reliable services like financial transactions, telemedicine, virtual and augmented reality, surveillance, and other applications. In order to ensure effective latency engineering, the delay variability needs to be accurately monitored and measured, in order to control it. This paper in brief describes causes of latency in fiber optical metro networks. Several available latency reduction techniques and solutions are also discussed, namely concerning usage of different chromatic dispersion compensation methods, low-latency amplifiers, optical fibers as well as other network elements.

Collagen Matrix Remodeling in Stented Pulmonary Arteries after Transapical Heart Valve Replacement.

PubMed

Ghazanfari, Samaneh; Driessen-Mol, Anita; Hoerstrup, Simon P; Baaijens, Frank P T; Bouten, Carlijn V C

2016-01-01

The use of valved stents for minimally invasive replacement of semilunar heart valves is expected to change the extracellular matrix and mechanical function of the native artery and may thus impair long-term functionality of the implant. Here we investigate the impact of the stent on matrix remodeling of the pulmonary artery in a sheep model, focusing on matrix composition and collagen (re)orientation of the host tissue. Ovine native pulmonary arteries were harvested 8 (n = 2), 16 (n = 4) and 24 (n = 2) weeks after transapical implantation of self-expandable stented heart valves. Second harmonic generation (SHG) microscopy was used to assess the collagen (re)orientation of fresh tissue samples. The collagen and elastin content was quantified using biochemical assays. SHG microscopy revealed regional differences in collagen organization in all explants. In the adventitial layer of the arterial wall far distal to the stent (considered as the control tissue), we observed wavy collagen fibers oriented in the circumferential direction. These circumferential fibers were more straightened in the adventitial layer located behind the stent. On the luminal side of the wall behind the stent, collagen fibers were aligned along the stent struts and randomly oriented between the struts. Immediately distal to the stent, however, fibers on both the luminal and the adventitial side of the wall were oriented in the axial direction, demonstrating the stent impact on the collagen structure of surrounding arterial tissues. Collagen orientation patterns did not change with implantation time, and biochemical analyses showed no changes in the trend of collagen and elastin content with implantation time or location of the vascular wall. We hypothesize that the collagen fibers on the adventitial side of the arterial wall and behind the stent straighten in response to the arterial stretch caused by oversizing of the stent. However, the collagen organization on the luminal side suggests that stent-induced remodeling is dominated by contact guidance. © 2016 S. Karger AG, Basel.

Constructing of Research-Oriented Learning Mode Based on Network Environment

ERIC Educational Resources Information Center

Wang, Ying; Li, Bing; Xie, Bai-zhi

2007-01-01

Research-oriented learning mode that based on network is significant to cultivate comprehensive-developing innovative person with network teaching in education for all-around development. This paper establishes a research-oriented learning mode by aiming at the problems existing in research-oriented learning based on network environment, and…

Computational Cardiac Anatomy Using MRI

PubMed Central

Beg, Mirza Faisal; Helm, Patrick A.; McVeigh, Elliot; Miller, Michael I.; Winslow, Raimond L.

2005-01-01

Ventricular geometry and fiber orientation may undergo global or local remodeling in cardiac disease. However, there are as yet no mathematical and computational methods for quantifying variation of geometry and fiber orientation or the nature of their remodeling in disease. Toward this goal, a landmark and image intensity-based large deformation diffeomorphic metric mapping (LDDMM) method to transform heart geometry into common coordinates for quantification of shape and form was developed. Two automated landmark placement methods for modeling tissue deformations expected in different cardiac pathologies are presented. The transformations, computed using the combined use of landmarks and image intensities, yields high-registration accuracy of heart anatomies even in the presence of significant variation of cardiac shape and form. Once heart anatomies have been registered, properties of tissue geometry and cardiac fiber orientation in corresponding regions of different hearts may be quantified. PMID:15508155

Optic axis determination accuracy for fiber-based polarization-sensitive optical coherence tomography.

PubMed

Park, B Hyle; Pierce, Mark C; Cense, Barry; de Boer, Johannes F

2005-10-01

We present a generalized analysis of fiber-based polarization-sensitive optical coherence tomography with an emphasis on determination of sample optic axis orientation. The polarization properties of a fiber-based system can cause an overall rotation in a Poincaré sphere representation such that the plane of possible measured sample optic axes for linear birefringence and diattenuation no longer lies in the QU-plane. The optic axis orientation can be recovered as an angle on this rotated plane, subject to an offset and overall indeterminacy in sign such that only the magnitude, but not the direction, of a change in orientation can be determined. We discuss the accuracy of optic axis determination due to a fundamental limit on the accuracy with which a polarization state can be determined as a function of signal-to-noise ratio.

Optic axis determination by fiber-based polarization-sensitive swept-source optical coherence tomography

NASA Astrophysics Data System (ADS)

Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

2011-03-01

We describe a fiber-based variable-incidence-angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3-D optical axis of birefringent biological tissues. Single-plane VIAPS- OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fiber on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fiber. A proposed algorithm based on the angle between Stokes vectors on the Poincaré sphere is confirmed to work for all settings of the sample arm fiber. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

Optical data communication: fundamentals and future directions

NASA Astrophysics Data System (ADS)

DeCusatis, Casimer M.

1998-12-01

An overview of optical data communications is provided, beginning with a brief history and discussion of the unique requirements that distinguish this subfield from related areas such as telecommunications. Each of the major datacom standards is then discussed, including the physical layer specification, distances and data rates, fiber and connector types, data frame structures, and network considerations. These standards can be categorized by their prevailing applications, either storage [Enterprise System Connection, Fiber Channel Connection, and Fiber Channel], coupling (Fiber Channel), or networking [Fiber Distributed Data Interface, Gigabit Ethernet, and asynchronous transfer mode/synchronous optical network]. We also present some emerging technologies and their applications, including parallel optical interconnects, plastic optical fiber, wavelength multiplexing, and free- space optical links. We conclude with some cost/performance trade-offs and predictions of future bandwidth trends.

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - Fourth FY 2015 Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Wollan, Eric J.

2015-11-13

During the last quarter of FY 2015, the following technical progress has been made toward project milestones: 1) PlastiComp used the PlastiComp direct in-line (D-LFT) Pushtrusion system to injection mold 40 30wt% LCF/PP parts with ribs, 40 30wt% LCF/PP parts without ribs, 10 30wt% LCF/PA66 parts with ribs, and 35 30wt% LCF/PA66 parts without ribs. In addition, purge materials from the injection molding nozzle were obtained for fiber length analysis, and molding parameters were sent to PNNL for process modeling. 2) Magna cut samples at four selected locations (named A, B, C and D) from the non-ribbed Magna-molded parts basedmore » on a plan discussed with PNNL and the team and shipped these samples to Virginia Tech for fiber orientation and length measurements. 3) Virginia Tech started fiber orientation and length measurements for the samples taken from the complex parts using Virginia Tech’s established procedure. 4) PNNL and Autodesk built ASMI models for the complex parts with and without ribs, reviewed process datasheets and performed preliminary analyses of these complex parts using the actual molding parameters received from Magna and PlastiComp to compare predicted to experimental mold filling patterns. 5) Autodesk assisted PNNL in developing the workflow to use Moldflow fiber orientation and length results in ABAQUS® simulations. 6) Autodesk advised the team on the practicality and difficulty of material viscosity characterization from the D-LFT process. 7) PNNL developed a procedure to import fiber orientation and length results from a 3D ASMI analysis to a 3D ABAQUS® model for structural analyses of the complex part for later weight reduction study. 8) In discussion with PNNL and Magna, Toyota developed mechanical test setups and built fixtures for three-point bending and torsion tests of the complex parts. 9) Toyota built a finite element model for the complex parts subjected to torsion loading. 10) PNNL built the 3D ABAQUS® model of the complex ribbed part subjected to 3-point bending. 11) University of Illinois (Prof. C.L. Tucker) advised the team on fiber orientation and fiber length measurement options, modeling issues as well as interpretation of data.« less

Connectivity and tissue microstructural alterations in right and left temporal lobe epilepsy revealed by diffusion spectrum imaging.

PubMed

Lemkaddem, Alia; Daducci, Alessandro; Kunz, Nicolas; Lazeyras, François; Seeck, Margitta; Thiran, Jean-Philippe; Vulliémoz, Serge

2014-01-01

Focal epilepsy is increasingly recognized as the result of an altered brain network, both on the structural and functional levels and the characterization of these widespread brain alterations is crucial for our understanding of the clinical manifestation of seizure and cognitive deficits as well as for the management of candidates to epilepsy surgery. Tractography based on Diffusion Tensor Imaging allows non-invasive mapping of white matter tracts in vivo. Recently, diffusion spectrum imaging (DSI), based on an increased number of diffusion directions and intensities, has improved the sensitivity of tractography, notably with respect to the problem of fiber crossing and recent developments allow acquisition times compatible with clinical application. We used DSI and parcellation of the gray matter in regions of interest to build whole-brain connectivity matrices describing the mutual connections between cortical and subcortical regions in patients with focal epilepsy and healthy controls. In addition, the high angular and radial resolution of DSI allowed us to evaluate also some of the biophysical compartment models, to better understand the cause of the changes in diffusion anisotropy. Global connectivity, hub architecture and regional connectivity patterns were altered in TLE patients and showed different characteristics in RTLE vs LTLE with stronger abnormalities in RTLE. The microstructural analysis suggested that disturbed axonal density contributed more than fiber orientation to the connectivity changes affecting the temporal lobes whereas fiber orientation changes were more involved in extratemporal lobe changes. Our study provides further structural evidence that RTLE and LTLE are not symmetrical entities and DSI-based imaging could help investigate the microstructural correlate of these imaging abnormalities.

Fiber to the home: next generation network

NASA Astrophysics Data System (ADS)

Yang, Chengxin; Guo, Baoping

2006-07-01

Next generation networks capable of carrying converged telephone, television (TV), very high-speed internet, and very high-speed bi-directional data services (like video-on-demand (VOD), Game etc.) strategy for Fiber To The Home (FTTH) is presented. The potential market is analyzed. The barriers and some proper strategy are also discussed. Several technical problems like various powering methods, optical fiber cables, and different network architecture are discussed too.

Fiber-To-The-Home: Current Issues And Strategies For A Bell Operating Company

NASA Astrophysics Data System (ADS)

Engel, Joel

1990-01-01

This decade has seen extensive use of fiber in the telephone network. Fiber is already pervasive in interoffice facilities, and is now being introduced into the local loop, which represents 90% of telephone circuit miles. In the feeder portion of the loop, the connection between the central office and remote terminals, fiber has already made significant inroads. In fact, Ameritech has more route miles of fiber in each of its five states than is in the entire network of the interexchange carrier whose advertisements stress their use of fiber.

Improving NIR model for the prediction of cotton fiber strength

USDA-ARS?s Scientific Manuscript database

Cotton fiber strength is an important quality characteristic that is directly related to the manufacturing of quality consumer goods. Currently, two types of instruments have been implemented to assess cotton fiber strength, namely, the automation oriented high volume instrument (HVI) and the labora...

Correlation of HVI vs. stelometer fiber strength and its application

USDA-ARS?s Scientific Manuscript database

Cotton fiber strength is an important quality characteristic that is directly related to the manufacturing of quality consumer goods. Currently, two types of instruments have been implemented to assess cotton fiber strength, namely, the automation oriented HVI and the laboratory based Stelometer. Ea...

On the performance of the moment approximation for the numerical computation of fiber stress in turbulent channel flow

NASA Astrophysics Data System (ADS)

Gillissen, J. J. J.; Boersma, B. J.; Mortensen, P. H.; Andersson, H. I.

2007-03-01

Fiber-induced drag reduction can be studied in great detail by means of direct numerical simulation [J. S. Paschkewitz et al., J. Fluid Mech. 518, 281 (2004)]. To account for the effect of the fibers, the Navier-Stokes equations are supplemented by the fiber stress tensor, which depends on the distribution function of fiber orientation angles. We have computed this function in turbulent channel flow, by solving the Fokker-Planck equation numerically. The results are used to validate an approximate method for calculating fiber stress, in which the second moment of the orientation distribution is solved. Since the moment evolution equations contain higher-order moments, a closure relation is required to obtain as many equations as unknowns. We investigate the performance of the eigenvalue-based optimal fitted closure scheme [J. S. Cintra and C. L. Tucker, J. Rheol. 39, 1095 (1995)]. The closure-predicted stress and flow statistics in two-way coupled simulations are within 10% of the "exact" Fokker-Planck solution.

Bipolar stimulation of a three-dimensional bidomain incorporating rotational anisotropy.

PubMed

Muzikant, A L; Henriquez, C S

1998-04-01

A bidomain model of cardiac tissue was used to examine the effect of transmural fiber rotation during bipolar stimulation in three-dimensional (3-D) myocardium. A 3-D tissue block with unequal anisotropy and two types of fiber rotation (none and moderate) was stimulated along and across fibers via bipolar electrodes on the epicardial surface, and the resulting steady-state interstitial (phi e) and transmembrane (Vm) potentials were computed. Results demonstrate that the presence of rotated fibers does not change the amount of tissue polarized by the point surface stimuli, but does cause changes in the orientation of phi e and Vm in the depth of the tissue, away from the epicardium. Further analysis revealed a relationship between the Laplacian of phi e, regions of virtual electrodes, and fiber orientation that was dependent upon adequacy of spatial sampling and the interstitial anisotropy. These findings help to understand the role of fiber architecture during extracellular stimulation of cardiac muscle.

A constrained maximization formulation to analyze deformation of fiber reinforced elastomeric actuators

NASA Astrophysics Data System (ADS)

Singh, Gaurav; Krishnan, Girish

2017-06-01

Fiber reinforced elastomeric enclosures (FREEs) are soft and smart pneumatic actuators that deform in a predetermined fashion upon inflation. This paper analyzes the deformation behavior of FREEs by formulating a simple calculus of variations problem that involves constrained maximization of the enclosed volume. The model accurately captures the deformed shape for FREEs with any general fiber angle orientation, and its relation with actuation pressure, material properties and applied load. First, the accuracy of the model is verified with existing literature and experiments for the popular McKibben pneumatic artificial muscle actuator with two equal and opposite families of helically wrapped fibers. Then, the model is used to predict and experimentally validate the deformation behavior of novel rotating-contracting FREEs, for which no prior literature exist. The generality of the model enables conceptualization of novel FREEs whose fiber orientations vary arbitrarily along the geometry. Furthermore, the model is deemed to be useful in the design synthesis of fiber reinforced elastomeric actuators for general axisymmetric desired motion and output force requirement.

Biodegradable composites with aligned hydroxyapatite nanoneedles.

PubMed

Sun, Shih-Po; Wei, Mei; Olson, James R; Shaw, Montgomery T

2012-10-01

We prepared an anisotropic bone graft composite to mimic the hierarchical structure of the natural bone in which aligned hydroxyapatite (HA) nanocrystals deposit along collagen fibers. To approach the modulus and strength of the bone, we incorporated synthesized HA nanoneedles and melt drawn poly(L-lactic acid) fibers in our composite as reinforcing components. Their preferred orientation was induced via a modified pultrusion process. The HA orientation distribution was examined using wide angle X-ray diffraction. Micromechanical Halpin-Tsai model predictions considering the amount, shape, and orientation distribution of HA were compared, favorably, with the experimental observations. Copyright © 2012 Wiley Periodicals, Inc.

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites. Topical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Wang, Jin

2016-06-01

This project aimed to integrate, optimize, and validate the fiber orientation and length distribution models previously developed and implemented in the Autodesk® Simulation Moldflow® Insight (ASMI) software package for injection-molded long-carbon-fiber (LCF) thermoplastic composite structures. The project was organized into two phases. Phase 1 demonstrated the ability of the advanced ASMI package to predict fiber orientation and length distributions in LCF/polypropylene (PP) and LCF/polyamide-6, 6 (PA66) plaques within 15% of experimental results. Phase 2 validated the advanced ASMI package by predicting fiber orientation and length distributions within 15% of experimental results for a complex three-dimensional (3D) Toyota automotive part injection-moldedmore » from LCF/PP and LCF/PA66 materials. Work under Phase 2 also included estimate of weight savings and cost impacts for a vehicle system using ASMI and structural analyses of the complex part. The present report summarizes the completion of Phases 1 and 2 work activities and accomplishments achieved by the team comprising Pacific Northwest National Laboratory (PNNL); Purdue University (Purdue); Virginia Polytechnic Institute and State University (Virginia Tech); Autodesk, Inc. (Autodesk); PlastiComp, Inc. (PlastiComp); Toyota Research Institute North America (Toyota); Magna Exteriors and Interiors Corp. (Magna); and University of Illinois. Figure 1 illustrates the technical approach adopted in this project that progressed from compounding LCF/PP and LCF/PA66 materials, to process model improvement and implementation, to molding and modeling LCF/PP and LCF/PA66 plaques. The lessons learned from the plaque study and the successful validation of improved process models for fiber orientation and length distributions for these plaques enabled the project to go to Phase 2 to mold, model, and optimize the 3D complex part.« less

Electroactive BaTiO3 nanoparticle-functionalized fibrous scaffolds enhance osteogenic differentiation of mesenchymal stem cells

PubMed Central

Li, Yiping; Dai, Xiaohan; Bai, Yunyang; Liu, Yun; Wang, Yuehong; Liu, Ousheng; Yan, Fei; Tang, Zhangui; Zhang, Xuehui; Deng, Xuliang

2017-01-01

It has been proven that the surface topographic cues of fiber arrangement can induce osteogenic differentiation of mesenchymal stem cells. However, this effect alone is weak and insufficient to meet the needs of regenerative medicine. In this work, electroactivity concept was introduced to enhance the osteoinductivity of fibrous scaffolds. The randomly oriented and aligned electroactive fibrous scaffolds of poly-(l-lactic acid) (PLLA) with incorporation of ferroelectric ceramic BaTiO3 (BTO) nanoparticles (NPs) were fabricated by electrospinning. Physicochemical properties, including fiber morphology, microstructure, composition, thermal stability, surface roughness, and surface wettability, of these fibrous scaffolds were studied. The dielectric properties of the scaffolds were evaluated. The results showed that the randomly oriented BTO/PLLA composite fibrous scaffolds had the highest dielectric permittivity of 1.19, which is of the same order of magnitude as the natural bone. The combined effects of fiber orientation and electrical activity on the osteogenic responses of bone marrow mesenchymal stem cells (BM-MSCs) were specifically investigated. Randomly oriented composite fibrous scaffolds significantly promoted polygonal spreading and encouraged early osteogenic differentiation in BM-MSCs, whereas aligned composite fibrous scaffolds promoted cell elongation and discouraged osteogenic differentiation. These results evidenced that randomly fiber orientation and biomimetic electric activity have combining effects on osteogenic differentiation of BM-MSCs. Our findings indicate that coupling effects of multi-physical properties should be paid more attention to mimic the microenvironment for enhancing osteogenic differentiation of BM-MSCs. PMID:28603415

Orientation of the N-terminal lobe of the myosin regulatory light chain in skeletal muscle fibers.

PubMed

Romano, Daniela; Brandmeier, Birgit D; Sun, Yin-Biao; Trentham, David R; Irving, Malcolm

2012-03-21

The orientation of the N-terminal lobe of the myosin regulatory light chain (RLC) in demembranated fibers of rabbit psoas muscle was determined by polarized fluorescence. The native RLC was replaced by a smooth muscle RLC with a bifunctional rhodamine probe attached to its A, B, C, or D helix. Fiber fluorescence data were interpreted using the crystal structure of the head domain of chicken skeletal myosin in the nucleotide-free state. The peak angle between the lever axis of the myosin head and the fiber or actin filament axis was 100-110° in relaxation, isometric contraction, and rigor. In each state the hook helix was at an angle of ∼40° to the lever/filament plane. The in situ orientation of the RLC D and E helices, and by implication of its N- and C-lobes, was similar in smooth and skeletal RLC isoforms. The angle between these two RLC lobes in rigor fibers was different from that in the crystal structure. These results extend previous crystallographic evidence for bending between the two lobes of the RLC to actin-attached myosin heads in muscle fibers, and suggest that such bending may have functional significance in contraction and regulation of vertebrate striated muscle. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Study on properties of CFRP fabricated by VA-RTM process

NASA Astrophysics Data System (ADS)

Jeoung, Sun Kyoung; Hwang, Ye Jin; Lee, Hyun Wook; Son, Soon Keun; Kim, Hyung Sik; Ha, Jin Uk

2016-03-01

Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90°→ 0°). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods.

Implementation of a tactical voice/data network over FDDI. [Fiber Distributed Data Interface

NASA Technical Reports Server (NTRS)

Bergman, L. A.; Halloran, F.; Martinez, J.

1988-01-01

An asynchronous high-speed fiber-optic local-area network is described that simultaneously supports packet data traffic with synchronous TI voice traffic over a standard asynchronous FDDI (fiber distributed data interface) token-ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multitier backbones. In addition, the higher layer packet data protocols may operate independently of those for the voice, thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions are performed external to the network with PABX equipment.

Remote sensing of nutrient deficiency in Lactuca sativa using neural networks for terrestrial and advanced life support applications

NASA Astrophysics Data System (ADS)

Sears, Edie Seldon

2000-12-01

A remote sensing study using reflectance and fluorescence spectra of hydroponically grown Lactuca sativa (lettuce) canopies was conducted. An optical receiver was designed and constructed to interface with a commercial fiber optic spectrometer for data acquisition. Optical parameters were varied to determine effects of field of view and distance to target on vegetation stress assessment over the test plant growth cycle. Feedforward backpropagation neural networks (NN) were implemented to predict the presence of canopy stress. Effects of spatial and spectral resolutions on stress predictions of the neural network were also examined. Visual inspection and fresh mass values failed to differentiate among controls, plants cultivated with 25% of the recommended concentration of phosphorous (P), and those cultivated with 25% nitrogen (N) based on fresh mass and visual inspection. The NN's were trained on input vectors created using reflectance and test day, fluorescence and test day, and reflectance, fluorescence, and test day. Four networks were created representing four levels of spectral resolution: 100-nm NN, 10-nm NN, 1-nm NN, and 0.1-nm NN. The 10-nm resolution was found to be sufficient for classifying extreme nitrogen deficiency in freestanding hydroponic lettuce. As a result of leaf angle and canopy structure broadband scattering intensity in the 700-nm to 1000-nm range was found to be the most useful portion of the spectrum in this study. More subtle effects of "greenness" and fluorescence emission were believed to be obscured by canopy structure and leaf orientation. As field of view was not as found to be as significant as originally believed, systems implementing higher repetitions over more uniformly oriented, i.e. smaller, flatter, target areas would provide for more discernible neural network input vectors. It is believed that this technique holds considerable promise for early detection of extreme nitrogen deficiency. Further research is recommended using stereoscopic digital cameras to quantify leaf area index, leaf shape, and leaf orientation as well as reflectance. Given this additional information fluorescence emission may also prove a more useful biological assay of freestanding vegetation.

Understanding the Relationship Between PTSD and Social Support: The Role of Negative Network Orientation

PubMed Central

Clapp, Joshua D.; Beck, J. Gayle

2009-01-01

Network orientation is conceptualized as an individual’s attitudes and expectations regarding the usefulness of support networks in coping with stress. The present research examined the potential for network orientation to explicate the well documented association between posttraumatic stress disorder (PTSD) and attenuated social support. Data collected from survivors of serious motor vehicle trauma (N = 458) were used to test the hypothesis that severity of PTSD would hold a significant indirect relationship with social support through negative network orientation. Childhood victimization and elapsed time from the accident were examined as potential moderators of this indirect relationship. Consistent with hypotheses, path analyses demonstrated a significant indirect relationship between PTSD and social support through negative network orientation. Specifically, this indirect effect was the result of a direct association between PTSD severity and negative network orientation and an inverse association between negative network orientation and social support. This pattern of relationships was invariant across mode of PTSD assessment (interview vs. self-report). No moderation effects were noted. These data suggest that network orientation may be an important factor in understanding interface of interpersonal processes and posttrauma pathology. PMID:19162260

Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

NASA Astrophysics Data System (ADS)

Ren, Fang; Huang, Xiaoshan; Wang, Jianping

2017-11-01

We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

Surface Properties of a Hooked Steel Fiber and their Effects on the Fiber Pullout and Composite Cracking 1. Experimental Study

NASA Astrophysics Data System (ADS)

Zesers, A.; Krūmiņš, J.

2014-09-01

Concrete as a material is brittle, but adding short steel fibers to the matrix can significantly improve its mechanical properties. The chemical adhesion between concrete and steel is weak, and the fiber pullout properties are based on fiber geometry and frictional forces. Single-fiber pullout tests of steel fibers with toothed and smooth surfaces were performed in order to characterize the effects of fiber surface facture. The influence of fiber form, surface facture, and fiber orientation (relative to the pullout direction) on the fiber withdrawal resistance and the maximum pullout force were studied.

Quantum key distribution over an installed multimode optical fiber local area network.

PubMed

Namekata, Naoto; Mori, Shigehiko; Inoue, Shuichiro

2005-12-12

We have investigated the possibility of a multimode fiber link for a quantum channel. Transmission of light in an extremely underfilled mode distribution promises a single-mode-like behavior in the multimode fiber. To demonstrate the performance of the fiber link we performed quantum key distribution, on the basis of the BB84 four-state protocol, over 550 m of an installed multimode optical fiber local area network, and the quantum-bit-error rate of 1.09 percent was achieved.

Crosstalk-aware virtual network embedding over inter-datacenter optical networks with few-mode fibers

NASA Astrophysics Data System (ADS)

Huang, Haibin; Guo, Bingli; Li, Xin; Yin, Shan; Zhou, Yu; Huang, Shanguo

2017-12-01

Virtualization of datacenter (DC) infrastructures enables infrastructure providers (InPs) to provide novel services like virtual networks (VNs). Furthermore, optical networks have been employed to connect the metro-scale geographically distributed DCs. The synergistic virtualization of the DC infrastructures and optical networks enables the efficient VN service over inter-DC optical networks (inter-DCONs). While the capacity of the used standard single-mode fiber (SSMF) is limited by their nonlinear characteristics. Thus, mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) could be employed to increase the capacity of optical networks. Whereas, modal crosstalk (XT) introduced by optical fibers and components deployed in the MDM optical networks impacts the performance of VN embedding (VNE) over inter-DCONs with FMFs. In this paper, we propose a XT-aware VNE mechanism over inter-DCONs with FMFs. The impact of XT is considered throughout the VNE procedures. The simulation results show that the proposed XT-aware VNE can achieves better performances of blocking probability and spectrum utilization compared to conventional VNE mechanisms.

Dynamics of small flexible fibers in turbulent channel flow

NASA Astrophysics Data System (ADS)

Marchioli, Cristian; Dotto, Diego; Soldati, Alfredo

2017-11-01

In this paper we investigate the dynamics of small flexible fibers in turbulent channel flow. Our aim is to examine the effect of local shear and turbulence anisotropy on the translation and rotation of fibers with different elongation and inertia. To these aims, we use a Eulerian-Lagrangian approach based on direct numerical simulation of turbulence in the dilute regime, and we model fibers, which are longer than the Kolmogorov scale, as chains of sub-Kolmogorov rods connected through ball-and-socket joints that enable bending and twisting. Velocity, orientation and concentration statistics, extracted from simulations at Reτ = 300 , are presented to give insights into the complex fibers-turbulence interactions that arise when non-sphericity and deformability add to inertial bias. Compared to fibers that translate and rotate as rigid bodies relative to the surrounding fluid, flexible fibers exhibit a stronger tendency to accumulate in the near-wall region, where they are trapped by the same mechanisms that govern preferential concentration of spherical particles. In such region, the mean shear is strong enough to reduce bending and stretch the fibers. Preferential segregation into low-speed streaks and preferential orientation in the mean flow direction are also observed.

Age-related morphological changes of the dermal matrix in human skin documented in vivo by multiphoton microscopy

NASA Astrophysics Data System (ADS)

Wang, Hequn; Shyr, Thomas; Fevola, Michael J.; Cula, Gabriela Oana; Stamatas, Georgios N.

2018-03-01

Two-photon fluorescence (TPF) and second harmonic generation (SHG) microscopy provide direct visualization of the skin dermal fibers in vivo. A typical method for analyzing TPF/SHG images involves averaging the image intensity and therefore disregarding the spatial distribution information. The goal of this study is to develop an algorithm to document age-related effects of the dermal matrix. TPF and SHG images were acquired from the upper inner arm, volar forearm, and cheek of female volunteers of two age groups: 20 to 30 and 60 to 80 years of age. The acquired images were analyzed for parameters relating to collagen and elastin fiber features, such as orientation and density. Both collagen and elastin fibers showed higher anisotropy in fiber orientation for the older group. The greatest difference in elastin fiber anisotropy between the two groups was found for the upper inner arm site. Elastin fiber density increased with age, whereas collagen fiber density decreased with age. The proposed analysis considers the spatial information inherent to the TPF and SHG images and provides additional insights into how the dermal fiber structure is affected by the aging process.

Non-destructive investigation of thermoplastic reinforced composites

DOE PAGES

Hassen, Ahmed; Taheri, Hossein; Vaidya, Uday

2016-05-09

This paper studies various manufacturing defects in glass fiber/Polypropylene (PP) composite parts and their methods of detection. Foreign Object Inclusion (FOI) of different shapes, sizes, and materials were placed in a glass fiber/PP panel made by compression molding. The paper aims to characterize the fiber orientation and fiber related defects such as fiber waviness in the composite specimen. Comprehensive investigation for different Non Destructive Evaluation (NDE) techniques, namely X-ray radiography and Ultrasonic Testing (UT) techniques to trace and characterize the embedded defects and the composite texture are presented. Conventional X-ray radiography successfully identified the fiber orientation in two dimension (2-D)more » plane; however, information for the sample depth was not captured. The radiography techniques showed low relative errors for the defect size measurements (maximum error was below 9.5%) when compared to the ultrasonic techniques. Ultrasonic techniques were able to map all the embedded artificial defects. Phase Array (PA) ultrasonic technique was able to precisely locate the FOI in the glass fiber/PP specimen. Nerveless, the shape and size of the defects were not accurately determined due to the high signal attenuation and distortion characteristics of the E-glass fiber.« less

The interface in tungsten fiber reinforced niobium metal-matrix composites. Final Report Ph.D. Thesis - Case Western Reserve Univ., Cleveland, OH

NASA Technical Reports Server (NTRS)

Grobstein, Toni L.

1989-01-01

The creep resistance of tungsten fiber reinforced niobium metal-matrix composites was evaluated. The interface region between the fiber and matrix was characterized by microhardness and electron probe microanalysis measurements which indicated that its properties were between those of fiber and matrix. However, the measured properties of the composite exceeded those calculated by the rule of mixtures even when the interface zone was assumed to retain all the strength of the fiber. The composite structure appeared to enhance the strengths of both the fibers and the matrix above what they exhibited in stand-alone tests. The effect of fiber orientation and matrix alloy composition on the fiber/matrix interface were also evaluated. Small alloying additions of zirconium and tungsten to the niobium matrix affected the creep resistance of the composites only slightly. A decrease in the creep resistance of the composite with increasing zirconium content in the matrix was ascribed to an increase in the diffusion rate of the fiber/matrix interdiffusion reaction, and a slight increase in the creep resistance of the composite was observed with an addition of 9 w percent tungsten to the matrix. In addition, Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis.

Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

PubMed Central

Khandalavala, Karl; Jiang, Jiang; Shuler, Franklin D.; Xie, Jingwei

2015-01-01

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion. PMID:25938562

Optical Fiber Networks for Remote Fiber Optic Sensors

PubMed Central

Fernandez-Vallejo, Montserrat; Lopez-Amo, Manuel

2012-01-01

This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered. PMID:22666011

The aortic valve microstructure: effects of transvalvular pressure.

PubMed

Sacks, M S; Smith, D B; Hiester, E D

1998-07-01

We undertook this study to establish a more quantitative understanding of the microstructural response of the aortic valve cusp to pressure loading. Fresh porcine aortic valves were fixed at transvalvular pressures ranging from 0 mmHg to 90 mmHg, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the valve cusps. At all pressures the fiber-preferred directions coursed along the circumferential direction. Increasing transvalvular pressure induced the greatest changes in fiber alignment between 0 and 1 mmHg, with no detectable change past 4 mmHg. When the fibrosa and ventricularis layers of the cusps were re-scanned separately, the fibrosa layer revealed a higher degree of orientation while the ventricularis was more randomly oriented. The degree of fiber orientation for both layers became more similar once the transvalvular pressure exceeded 4 mmHg, and the layers were almost indistinguishable by 60 mmHg. It is possible that, in addition to retracting the aortic cusp during systole, the ventricularis mechanically may contribute to the diastolic cuspal stiffness at high transvalvular pressures, which may help to prevent over distention of the cusp. Our results suggest a complex, highly heterogeneous structural response to transvalvular pressure on a fiber level that will have to be duplicated in future bioprosthetic heart valve designs.

Overview of hybrid fiber-coaxial network deployment in the deregulated UK environment

NASA Astrophysics Data System (ADS)

Cox, Alan L.

1995-11-01

Cable operators in the U.K. enjoy unprecedented license to construct networks and operate cable TV and telecommunications services within their franchise areas. In general, operators have built hybrid-fiber-coax (HFC) networks for cable TV in parallel with fiber-copper-pair networks for telephony. The commonly used network architectures are reviewed, together with their present and future capacities. Despite this dual-technology approach, there is considerable interest in the integration of telephony services onto the HFC network and the development of new interactive services for which HFC may be more suitable than copper pairs. Certain technological and commercial developments may have considerable significance for HFC networks and their operators. These include the digitalization of TV distribution and the rising demand for high-rate digital access lines. Possible scenarios are discussed.

Molecular Modeling of Aerospace Polymer Matrices Including Carbon Nanotube-Enhanced Epoxy

NASA Astrophysics Data System (ADS)

Radue, Matthew S.

Carbon fiber (CF) composites are increasingly replacing metals used in major structural parts of aircraft, spacecraft, and automobiles. The current limitations of carbon fiber composites are addressed through computational material design by modeling the salient aerospace matrix materials. Molecular Dynamics (MD) models of epoxies with and without carbon nanotube (CNT) reinforcement and models of pure bismaleimides (BMIs) were developed to elucidate structure-property relationships for improved selection and tailoring of matrices. The influence of monomer functionality on the mechanical properties of epoxies is studied using the Reax Force Field (ReaxFF). From deformation simulations, the Young's modulus, yield point, and Poisson's ratio are calculated and analyzed. The results demonstrate an increase in stiffness and yield strength with increasing resin functionality. Comparison between the network structures of distinct epoxies is further advanced by the Monomeric Degree Index (MDI). Experimental validation demonstrates the MD results correctly predict the relationship in Young's moduli for all epoxies modeled. Therefore, the ReaxFF is confirmed to be a useful tool for studying the mechanical behavior of epoxies. While epoxies have been well-studied using MD, there has been no concerted effort to model cured BMI polymers due to the complexity of the network-forming reactions. A novel, adaptable crosslinking framework is developed for implementing 5 distinct cure reactions of Matrimid-5292 (a BMI resin) and investigating the network structure using MD simulations. The influence of different cure reactions and extent of curing are analyzed on the several thermo-mechanical properties such as mass density, glass transition temperature, coefficient of thermal expansion, elastic moduli, and thermal conductivity. The developed crosslinked models correctly predict experimentally observed trends for various properties. Finally, the epoxies modeled (di-, tri-, and tetra-functionalresins) are simulated with embedded CNT to understand how the affinity to nanoparticles affects the mechanical response. Multiscale modeling techniques are then employed to translate the molecular phenomena observed to predict the behavior of realistic composites. The effective stiffness of hybrid composites are predicted for CNT/epoxy composites with randomly oriented CNTs, for CF/CNT/epoxy systems with aligned CFs and randomly oriented CNTs, and for woven CF/CNT/epoxy fabric with randomly oriented CNTs. The results indicate that in the CNT/epoxy systems the epoxy type has a significant influence on the elastic properties. For the CF/CNT/epoxy hybrid composites, the axial modulus is highly influenced by CF concentration, while the transverse modulus is primarily affected by the CNT weight fraction.

Numerical Estimation of the Elastic Properties of Thin-Walled Structures Manufactured from Short-Fiber-Reinforced Thermoplastics

NASA Astrophysics Data System (ADS)

Altenbach, H.; Naumenko, K.; L'vov, G. I.; Pilipenko, S. N.

2003-05-01

A model which allows us to estimate the elastic properties of thin-walled structures manufactured by injection molding is presented. The starting step is the numerical prediction of the microstructure of a short-fiber-reinforced composite developed during the filling stage of the manufacturing process. For this purpose, the Moldflow Plastic Insight® commercial program is used. As a result of simulating the filling process, a second-rank orientation tensor characterizing the microstructure of the material is obtained. The elastic properties of the prepared material locally depend on the orientational distribution of fibers. The constitutive equation is formulated by means of orientational averaging for a given orientation tensor. The tensor of elastic material properties is computed and translated into the format for a stress-strain analysis based on the ANSYSÒ finite-element code. The numerical procedure and the convergence of results are discussed for a thin strip, a rectangular plate, and a shell of revolution. The influence of manufacturing conditions on the stress-strain state of statically loaded thin-walled elements is illustrated.

Determination of composition and structure of spongy bone tissue in human head of femur by Raman spectral mapping.

PubMed

Kozielski, M; Buchwald, T; Szybowicz, M; Błaszczak, Z; Piotrowski, A; Ciesielczyk, B

2011-07-01

Biomechanical properties of bone depend on the composition and organization of collagen fibers. In this study, Raman microspectroscopy was employed to determine the content of mineral and organic constituents and orientation of collagen fibers in spongy bone in the human head of femur at the microstructural level. Changes in composition and structure of trabecula were illustrated using Raman spectral mapping. The polarized Raman spectra permit separate analysis of local variations in orientation and composition. The ratios of ν₂PO₄³⁻/Amide III, ν₄PO₄³⁻/Amide III and ν₁CO₃²⁻/ν₂PO₄³⁻ are used to describe relative amounts of spongy bone components. The ν₁PO₄³⁻/Amide I ratio is quite susceptible to orientation effect and brings information on collagen fibers orientation. The results presented illustrate the versatility of the Raman method in the study of bone tissue. The study permits better understanding of bone physiology and evaluation of the biomechanical properties of bone.

Satellites vs. fiber optics based networks and services - Road map to strategic planning

NASA Astrophysics Data System (ADS)

Marandi, James H. R.

An overview of a generic telecommunications network and its components is presented, and the current developments in satellite and fiber optics technologies are discussed with an eye on the trends in industry. A baseline model is proposed, and a cost comparison of fiber- vs satellite-based networks is made. A step-by-step 'road map' to the successful strategic planning of telecommunications services and facilities is presented. This road map provides for optimization of the current and future networks and services through effective utilization of both satellites and fiber optics. The road map is then applied to different segments of the telecommunications industry and market place, to show its effectiveness for the strategic planning of executives of three types: (1) those heading telecommunications manufacturing concerns, (2) those leading communication service companies, and (3) managers of telecommunication/MIS departments of major corporations. Future networking issues, such as developments in integrated-services digital network standards and technologies, are addressed.

Electrospun oriented gelatin-hydroxyapatite fiber scaffolds for bone tissue engineering.

PubMed

Salifu, Ali A; Lekakou, Constantina; Labeed, Fatima H

2017-07-01

Tissue engineering of human fetal osteoblast cells was investigated on gelatin-hydroxyapatite (HA), crosslinked, electrospun oriented fiber scaffolds at the different HA concentrations of 0, 10, 20, and 25 wt % in the dry fibers and different fiber diameter, pore size and porosity of scaffolds. Rheological tests and proton nuclear magnetic resonance spectroscopy were conducted for all solutions used for electrospinning. It was found that 25 wt % HA-gelatin scaffolds electrospun at 20 kV led to the greatest cell attachment, cell proliferation and extracellular matrix (ECM) production while fiber orientation improved the mechanical properties, where crosslinked electrospun 25 wt % HA-gelatin fiber scaffolds yielded a Young's modulus in the range of 0.5-0.9 GPa and a tensile strength in the range of 4-10 MPa in the fiber direction for an applied voltage of 20-30 kV, respectively, in the electrospinning of scaffolds. Biological characterization of cell seeded scaffolds yielded the rate of cell growth and ECM (collagen and calcium) production by the cells as a function of time; it included cell seeding efficiency tests, alamar blue cell proliferation assay, alkaline phosphate (ALP) assay, collagen assay, calcium colorimetric assay, fluorescence microscopy for live and dead cells, and scanning electron microscopy for cell culture from 1 to 18 days. After 18 days, cells seeded and grown on the 25 wt % HA-gelatin scaffold, electrospun at 20 kV, reached production of collagen at 370 μg/L and calcium production at 0.8 mM. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1911-1926, 2017. © 2017 Wiley Periodicals, Inc.

Automated correction of improperly rotated diffusion gradient orientations in diffusion weighted MRI.

PubMed

Jeurissen, Ben; Leemans, Alexander; Sijbers, Jan

2014-10-01

Ensuring one is using the correct gradient orientations in a diffusion MRI study can be a challenging task. As different scanners, file formats and processing tools use different coordinate frame conventions, in practice, users can end up with improperly oriented gradient orientations. Using such wrongly oriented gradient orientations for subsequent diffusion parameter estimation will invalidate all rotationally variant parameters and fiber tractography results. While large misalignments can be detected by visual inspection, small rotations of the gradient table (e.g. due to angulation of the acquisition plane), are much more difficult to detect. In this work, we propose an automated method to align the coordinate frame of the gradient orientations with that of the corresponding diffusion weighted images, using a metric based on whole brain fiber tractography. By transforming the gradient table and measuring the average fiber trajectory length, we search for the transformation that results in the best global 'connectivity'. To ensure a fast calculation of the metric we included a range of algorithmic optimizations in our tractography routine. To make the optimization routine robust to spurious local maxima, we use a stochastic optimization routine that selects a random set of seed points on each evaluation. Using simulations, we show that our method can recover the correct gradient orientations with high accuracy and precision. In addition, we demonstrate that our technique can successfully recover rotated gradient tables on a wide range of clinically realistic data sets. As such, our method provides a practical and robust solution to an often overlooked pitfall in the processing of diffusion MRI. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical back propagation for fiber optic networks with hybrid EDFA Raman amplification.

PubMed

Liang, Xiaojun; Kumar, Shiva

2017-03-06

We have investigated an optical back propagation (OBP) method to compensate for propagation impairments in fiber optic networks with lumped Erbium doped fiber amplifier (EDFA) and/or distributed Raman amplification. An OBP module consists of an optical phase conjugator (OPC), optical amplifiers and dispersion varying fibers (DVFs). We derived a semi-analytical expression that calculates the dispersion profile of DVF. The OBP module acts as a nonlinear filter that fully compensates for the nonlinear distortions due to signal propagation in a transmission fiber, and is applicable for fiber optic networks with reconfigurable optical add-drop multiplexers (ROADMs). We studied a wavelength division multiplexing (WDM) network with 3000 km transmission distance and 64-quadrature amplitude modulation (QAM) modulation. OBP brings 5.8 dB, 5.9 dB and 6.1 dB Q-factor gains over linear compensation for systems with full EDFA amplification, hybrid EDFA/Raman amplification, and full Raman amplification, respectively. In contrast, digital back propagation (DBP) or OPC-only systems provide only 0.8 ~ 1.5 dB Q-factor gains.

Integrating quantum key distribution with classical communications in backbone fiber network.

PubMed

Mao, Yingqiu; Wang, Bi-Xiao; Zhao, Chunxu; Wang, Guangquan; Wang, Ruichun; Wang, Honghai; Zhou, Fei; Nie, Jimin; Chen, Qing; Zhao, Yong; Zhang, Qiang; Zhang, Jun; Chen, Teng-Yun; Pan, Jian-Wei

2018-03-05

Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics. The desire to reduce costs and increase robustness in real-world applications has motivated the study of coexistence between QKD and intense classical data traffic in a single fiber. Previous works on coexistence in metropolitan areas have used wavelength-division multiplexing, however, coexistence in backbone fiber networks remains a great experimental challenge, as Tbps data of up to 20 dBm optical power is transferred, and much more noise is generated for QKD. Here we present for the first time, to the best of our knowledge, the integration of QKD with a commercial backbone network of 3.6 Tbps classical data at 21 dBm launch power over 66 km fiber. With 20 GHz pass-band filtering and large effective core area fibers, real-time secure key rates can reach 4.5 kbps and 5.1 kbps for co-propagation and counter-propagation at the maximum launch power, respectively. This demonstrates feasibility and represents an important step towards building a quantum network that coexists with the current backbone fiber infrastructure of classical communications.

Energy-efficient rings mechanism for greening multisegment fiber-wireless access networks

NASA Astrophysics Data System (ADS)

Gong, Xiaoxue; Guo, Lei; Hou, Weigang; Zhang, Lincong

2013-07-01

Through integrating advantages of optical and wireless communications, the Fiber-Wireless (FiWi) has become a promising solution for the "last-mile" broadband access. In particular, greening FiWi has attained extensive attention, because the access network is a main energy contributor in the whole infrastructure. However, prior solutions of greening FiWi shut down or sleep unused/minimally used optical network units for a single segment, where we deploy only one optical linear terminal. We propose a green mechanism referred to as energy-efficient ring (EER) for multisegment FiWi access networks. We utilize an integer linear programming model and a generic algorithm to generate clusters, each having the shortest distance of fully connected segments of its own. Leveraging the backtracking method for each cluster, we then connect segments through fiber links, and the shortest distance fiber ring is constructed. Finally, we sleep low load segments and forward affected traffic to other active segments on the same fiber ring by our sleeping scheme. Experimental results show that our EER mechanism significantly reduces the energy consumption at the slightly additional cost of deploying fiber links.

Understanding the role of the cytoskeleton in wood formation in angiosperm trees: hybrid aspen (Populus tremula x P. tremuloides) as the model species.

PubMed

Chaffey, Nigel; Barlow, Peter; Sundberg, Björn

2002-03-01

The involvement of microfilaments and microtubules in the development of the radial and axial components of secondary xylem (wood) in hybrid aspen (Populus tremula L. x P. tremuloides Michx.) was studied by indirect immunofluorescent localization techniques. In addition to cambial cells, the differentiated cell types considered were early- and late-wood vessel elements, axial parenchyma, normal-wood fibers and gelatinous fibers, and contact and isolation ray cells. Microfilaments were rare in ray cambial cells, but were abundant and axially arranged in their derivatives once cell elongation had begun, and persisted in that orientation in mature ray cells. Microfilaments were axially arranged in fusiform cambial cells and persisted in that orientation in all xylem derivatives of those cells. Microtubules were randomly oriented in ray and fusiform cells of the cambial zone. Dense arrays of parallel-aligned microtubules were oriented near axially in the developing gelatinous fibers, but at a wide range of angles in normal-wood fibers. Ellipses of microfilaments were associated with pit development in fiber cells and isolation ray cells. Rings of co-localized microtubules and microfilaments were associated with developing inter-vessel bordered pits and vessel-contact ray cell contact pits, and, in the case of bordered pits, these rings decreased in diameter as the over-arching pit border increased in size. Although only microtubules were seen at the periphery of the perforation plate of vessel elements, a prominent meshwork of microfilaments overlaid the perforation plate itself. A consensus view of the roles of the cytoskeleton during wood formation in angiosperm trees is presented.

Arterial extracellular matrix: a mechanobiological study of the contributions and interactions of elastin and collagen.

PubMed

Chow, Ming-Jay; Turcotte, Raphaël; Lin, Charles P; Zhang, Yanhang

2014-06-17

The complex network structure of elastin and collagen extracellular matrix (ECM) forms the primary load bearing components in the arterial wall. The structural and mechanobiological interactions between elastin and collagen are important for properly functioning arteries. Here, we examined the elastin and collagen organization, realignment, and recruitment by coupling mechanical loading and multiphoton imaging. Two-photon excitation fluorescence and second harmonic generation methods were performed with a multiphoton video-rate microscope to capture real time changes to the elastin and collagen structure during biaxial deformation. Enzymatic removal of elastin was performed to assess the structural changes of the remaining collagen structure. Quantitative analysis of the structural changes to elastin and collagen was made using a combination of two-dimensional fast Fourier transform and fractal analysis, which allows for a more complete understanding of structural changes. Our study provides new quantitative evidence, to our knowledge on the sequential engagement of different arterial ECM components in response to mechanical loading. The adventitial collagen exists as large wavy bundles of fibers that exhibit fiber engagement after 20% strain. The medial collagen is engaged throughout the stretching process, and prominent elastic fiber engagement is observed up to 20% strain after which the engagement plateaus. The fiber orientation distribution functions show remarkably different changes in the ECM structure in response to mechanical loading. The medial collagen shows an evident preferred circumferential distribution, however the fiber families of adventitial collagen are obscured by their waviness at no or low mechanical strains. Collagen fibers in both layers exhibit significant realignment in response to unequal biaxial loading. The elastic fibers are much more uniformly distributed and remained relatively unchanged due to loading. Removal of elastin produces similar structural changes in collagen as mechanical loading. Our study suggests that the elastic fibers are under tension and impart an intrinsic compressive stress on the collagen. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Crystallography of Alumina-YAG-Eutectic

NASA Technical Reports Server (NTRS)

Farmer, Serene C.; Sayir, Ali; Dickerson, Robert M.; Matson, Lawrence E.

2000-01-01

Multiple descriptions of the alumina-YAG eutectic crystallography appear in the ceramic literature. The orientation between two phases in a eutectic system has direct impact on residual stress, morphology, microstructural stability, and high temperature mechanical properties. A study to demonstrate that the different crystallographic relationships can be correlated with different growth constraints was undertaken. Fibers produced by Laser-Heated Float Zone (LHFZ) and Edge-defined Film-fed Growth (EFG) were examined. A map of the orientation relationship between Al2O3 and Y3Al5O12 and their relationship to the fiber growth axis as a function of pull rate are presented. Regions in which a single orientation predominates are identified.

Investigation of ferroelectric liquid crystal orientation in the silica microcapillaries

NASA Astrophysics Data System (ADS)

Budaszewski, D.; Domański, A. W.; Woliński, T. R.

2013-05-01

In the paper we present our recent results concerning the orientation of ferroelectric liquid crystal molecules inside silica micro capillaries. We have infiltrated the silica micro capillaries with experimental ferroelectric liquid crystal material W-260K synthesized in the Military University of Technology. The infiltrated micro capillaries were observed under the polarization microscope while both a polarizer and an analyzer were crossed. The studies on the orientation of ferroelectric liquid crystal molecules may contribute to further studies on behavior of this group of liquid crystal materials inside photonic crystal fiber. The obtained results may lead to design of a new type of fast optical fiber sensors.

Cyclic stretch-induced stress fiber dynamics - Dependence on strain rate, Rho-kinase and MLCK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Chin-Fu; Haase, Candice; Deguchi, Shinji

2010-10-22

Research highlights: {yields} Cyclic stretch induces stress fiber disassembly, reassembly and fusion perpendicular to the direction of stretch. {yields} Stress fiber disassembly and reorientation were not induced at low stretch frequency. {yields} Stretch caused actin fiber formation parallel to stretch in distinct locations in cells treated with Rho-kinase and MLCK inhibitors. -- Abstract: Stress fiber realignment is an important adaptive response to cyclic stretch for nonmuscle cells, but the mechanism by which such reorganization occurs is not known. By analyzing stress fiber dynamics using live cell microscopy, we revealed that stress fiber reorientation perpendicular to the direction of cyclic uniaxialmore » stretching at 1 Hz did not involve disassembly of the stress fiber distal ends located at focal adhesion sites. Instead, these distal ends were often used to assemble new stress fibers oriented progressively further away from the direction of stretch. Stress fiber disassembly and reorientation were not induced when the frequency of stretch was decreased to 0.01 Hz, however. Treatment with the Rho-kinase inhibitor (Y27632) reduced stress fibers to thin fibers located in the cell periphery which bundled together to form thick fibers oriented parallel to the direction of stretching at 1 Hz. In contrast, these thin fibers remained diffuse in cells subjected to stretch at 0.01 Hz. Cyclic stretch at 1 Hz also induced actin fiber formation parallel to the direction of stretch in cells treated with the myosin light chain kinase (MLCK) inhibitor ML-7, but these fibers were located centrally rather than peripherally. These results shed new light on the mechanism by which stress fibers reorient in response to cyclic stretch in different regions of the actin cytoskeleton.« less

A localized Richardson-Lucy algorithm for fiber orientation estimation in high angular resolution diffusion imaging.

PubMed

Liu, Xiaozheng; Yuan, Zhenming; Guo, Zhongwei; Xu, Dongrong

2015-05-01

Diffusion tensor imaging is widely used for studying neural fiber trajectories in white matter and for quantifying changes in tissue using diffusion properties at each voxel in the brain. To better model the nature of crossing fibers within complex architectures, rather than using a simplified tensor model that assumes only a single fiber direction at each image voxel, a model mixing multiple diffusion tensors is used to profile diffusion signals from high angular resolution diffusion imaging (HARDI) data. Based on the HARDI signal and a multiple tensors model, spherical deconvolution methods have been developed to overcome the limitations of the diffusion tensor model when resolving crossing fibers. The Richardson-Lucy algorithm is a popular spherical deconvolution method used in previous work. However, it is based on a Gaussian distribution, while HARDI data are always very noisy, and the distribution of HARDI data follows a Rician distribution. This current work aims to present a novel solution to address these issues. By simultaneously considering both the Rician bias and neighbor correlation in HARDI data, the authors propose a localized Richardson-Lucy (LRL) algorithm to estimate fiber orientations for HARDI data. The proposed method can simultaneously reduce noise and correct the Rician bias. Mean angular error (MAE) between the estimated Fiber orientation distribution (FOD) field and the reference FOD field was computed to examine whether the proposed LRL algorithm offered any advantage over the conventional RL algorithm at various levels of noise. Normalized mean squared error (NMSE) was also computed to measure the similarity between the true FOD field and the estimated FOD filed. For MAE comparisons, the proposed LRL approach obtained the best results in most of the cases at different levels of SNR and b-values. For NMSE comparisons, the proposed LRL approach obtained the best results in most of the cases at b-value = 3000 s/mm(2), which is the recommended schema for HARDI data acquisition. In addition, the FOD fields estimated by the proposed LRL approach in regions of fiber crossing regions using real data sets also showed similar fiber structures which agreed with common acknowledge in these regions. The novel spherical deconvolution method for improved accuracy in investigating crossing fibers can simultaneously reduce noise and correct Rician bias. With the noise smoothed and bias corrected, this algorithm is especially suitable for estimation of fiber orientations in HARDI data. Experimental results using both synthetic and real imaging data demonstrated the success and effectiveness of the proposed LRL algorithm.

Automated Inspection of Defects in Optical Fiber Connector End Face Using Novel Morphology Approaches.

PubMed

Mei, Shuang; Wang, Yudan; Wen, Guojun; Hu, Yang

2018-05-03

Increasing deployment of optical fiber networks and the need for reliable high bandwidth make the task of inspecting optical fiber connector end faces a crucial process that must not be neglected. Traditional end face inspections are usually performed by manual visual methods, which are low in efficiency and poor in precision for long-term industrial applications. More seriously, the inspection results cannot be quantified for subsequent analysis. Aiming at the characteristics of typical defects in the inspection process for optical fiber end faces, we propose a novel method, “difference of min-max ranking filtering” (DO2MR), for detection of region-based defects, e.g., dirt, oil, contamination, pits, and chips, and a special model, a “linear enhancement inspector” (LEI), for the detection of scratches. The DO2MR is a morphology method that intends to determine whether a pixel belongs to a defective region by comparing the difference of gray values of pixels in the neighborhood around the pixel. The LEI is also a morphology method that is designed to search for scratches at different orientations with a special linear detector. These two approaches can be easily integrated into optical inspection equipment for automatic quality verification. As far as we know, this is the first time that complete defect detection methods for optical fiber end faces are available in the literature. Experimental results demonstrate that the proposed DO2MR and LEI models yield good comprehensive performance with high precision and accepted recall rates, and the image-level detection accuracies reach 96.0 and 89.3%, respectively.

A spectral approach for the quantitative description of cardiac collagen network from nonlinear optical imaging.

PubMed

Masè, Michela; Cristoforetti, Alessandro; Avogaro, Laura; Tessarolo, Francesco; Piccoli, Federico; Caola, Iole; Pederzolli, Carlo; Graffigna, Angelo; Ravelli, Flavia

2015-01-01

The assessment of collagen structure in cardiac pathology, such as atrial fibrillation (AF), is essential for a complete understanding of the disease. This paper introduces a novel methodology for the quantitative description of collagen network properties, based on the combination of nonlinear optical microscopy with a spectral approach of image processing and analysis. Second-harmonic generation (SHG) microscopy was applied to atrial tissue samples from cardiac surgery patients, providing label-free, selective visualization of the collagen structure. The spectral analysis framework, based on 2D-FFT, was applied to the SHG images, yielding a multiparametric description of collagen fiber orientation (angle and anisotropy indexes) and texture scale (dominant wavelength and peak dispersion indexes). The proof-of-concept application of the methodology showed the capability of our approach to detect and quantify differences in the structural properties of the collagen network in AF versus sinus rhythm patients. These results suggest the potential of our approach in the assessment of collagen properties in cardiac pathologies related to a fibrotic structural component.

Unique sodium phosphosilicate glasses designed through extended topological constraint theory.

PubMed

Zeng, Huidan; Jiang, Qi; Liu, Zhao; Li, Xiang; Ren, Jing; Chen, Guorong; Liu, Fude; Peng, Shou

2014-05-15

Sodium phosphosilicate glasses exhibit unique properties with mixed network formers, and have various potential applications. However, proper understanding on the network structures and property-oriented methodology based on compositional changes are lacking. In this study, we have developed an extended topological constraint theory and applied it successfully to analyze the composition dependence of glass transition temperature (Tg) and hardness of sodium phosphosilicate glasses. It was found that the hardness and Tg of glasses do not always increase with the content of SiO2, and there exist maximum hardness and Tg at a certain content of SiO2. In particular, a unique glass (20Na2O-17SiO2-63P2O5) exhibits a low glass transition temperature (589 K) but still has relatively high hardness (4.42 GPa) mainly due to the high fraction of highly coordinated network former Si((6)). Because of its convenient forming and manufacturing, such kind of phosphosilicate glasses has a lot of valuable applications in optical fibers, optical amplifiers, biomaterials, and fuel cells. Also, such methodology can be applied to other types of phosphosilicate glasses with similar structures.

Constitutive Modeling of Nanotube/Polymer Composites with Various Nanotube Orientations

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Gates, Thomas S.

2002-01-01

In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT) with various orientations with respect to the bulk material coordinates. A nanotube, the local polymer adjacent to the nanotube, and the nanotube/polymer interface have been modeled as an equivalent-continuum fiber by using an equivalent-continuum modeling method. The equivalent-continuum fiber accounts for the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composite. As an example, the proposed approach is used for the constitutive modeling of a SWNT/LaRC-SI (with a PmPV interface) composite system, with aligned nanotubes, three-dimensionally randomly oriented nanotubes, and nanotubes oriented with varying degrees of axisymmetry. It is shown that the Young s modulus is highly dependent on the SWNT orientation distribution.

Influence of injection molding process parameters on fiber concentration distribution in long glass fiber reinforced polypropylene

NASA Astrophysics Data System (ADS)

Scantamburlo, Andrea; Gazzola, Luca; Sorgato, Marco; Lucchetta, Giovanni

2018-05-01

In parts manufactured by injection molding of long glass fiber reinforced polypropylene, the local fiber orientation, fiber concentration and fiber length distribution varies along both the thickness direction and the flow path. This heterogeneous microstructure significantly influences the mechanical properties variability in the molded parts. The aim of this work is to investigate the influence of the matrix viscosity, the injection speed and the mold geometry on the fiber concentration distribution. In particular, the factors involved in fiber-matrix separation and fiber pull-out during the injection phases were analyzed in order to understand the phenomenon.

Fiber vs Rolling Texture: Stress State Dependence for Cold-Drawn Wire

NASA Astrophysics Data System (ADS)

Zorina, M. A.; Karabanalov, M. S.; Stepanov, S. I.; Demakov, S. L.; Loginov, Yu. N.; Lobanov, M. L.

2018-02-01

The texture of the cold-drawn copper wire was investigated along the radius using electron backscatter diffraction. The complex fiber texture of the central region of the wire was considered as the rolling texture consisting of a set of preferred orientations. The texture of the periphery region was revealed to be similar to the shear texture. The orientation-dependent properties of the wire were proven to be determined by the texture of the near-surface layers.

Tensile and burning properties of clay/phenolic/GF composite and its application

NASA Astrophysics Data System (ADS)

Diharjo, Kuncoro; Armunanto, V. Bram; Kristiawan, S. Adi

2016-03-01

Composite material has been widely used in automotive due to its properties can be improved by combining with reinforcement, like fiber and particle to enhance mechanical properties and burning resistance. This study aims to investigate the tensile and burning properties of hybrid composite combining glass fiber and clay in phenolic resin. The clay was produced from roof tile rejected by tile industries in Sokka, Kebumen, Indonesia. The composite was made using a press mold method for different number of laminates and orientation of woven-roving-glass-fiber/ WRGF (0/90 and ±45), and the total volume fraction of fiber and clay is constant 40%. The specimens were tested using universal testing machine for tensile properties and burning tests apparatus for burning resistance (time to ignite/ TTI and burning rate/ BR). The enhancing of the Clay/Penolic/GF composite can be performed by the increasing of GF laminates, and the composite with 0/90 orientation of WRGF has higher tensile strength and modulus compared to that with ±45 orientation of WRGF. Both composite with 0/90 and ±45 orientation of WRGF have similar burning resistance (TTI and BR) and the composite containing 13 laminates of WR-GF shows the best burning resistance. According to these properties, this composite has good opportunity to be applied as car body panels or other structure in industries due to save weight and high burning resistance.

Highly oriented carbon fiber–polymer composites via additive manufacturing

DOE PAGES

Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; ...

2014-10-16

Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

Thermal and Mechanical Buckling Analysis of Hypersonic Aircraft Hat-Stiffened Panels With Varying Face Sheet Geometry and Fiber Orientation

NASA Technical Reports Server (NTRS)

Ko, William L.

1996-01-01

Mechanical and thermal buckling behavior of monolithic and metal-matrix composite hat-stiffened panels were investigated. The panels have three types of face-sheet geometry: Flat face sheet, microdented face sheet, and microbulged face sheet. The metal-matrix composite panels have three types of face-sheet layups, each of which is combined with various types of hat composite layups. Finite-element method was used in the eigenvalue extractions for both mechanical and thermal buckling. The thermal buckling analysis required both eigenvalue and material property iterations. Graphical methods of the dual iterations are shown. The mechanical and thermal buckling strengths of the hat-stiffened panels with different face-sheet geometry are compared. It was found that by just microdenting or microbulging of the face sheet, the axial, shear, and thermal buckling strengths of both types of hat-stiffened panels could be enhanced considerably. This effect is more conspicuous for the monolithic panels. For the metal-matrix composite panels, the effect of fiber orientations on the panel buckling strengths was investigated in great detail, and various composite layup combinations offering, high panel buckling strengths are presented. The axial buckling strength of the metal-matrix panel was sensitive to the change of hat fiber orientation. However, the lateral, shear, and thermal buckling strengths were insensitive to the change of hat fiber orientation.

The radio-on-fiber-wavelength-division-multiplexed-passive-optical network (WDM-RoF-PON) for wireless and wire layout with linearly-polarized dual-wavelength fiber laser and carrier reusing

NASA Astrophysics Data System (ADS)

Ji, Wei; Chang, Jun

2013-07-01

In this paper, we design a WDM-RoF-PON based on linearly-polarized dual-wavelength fiber laser and CSRZ-DPSK, which can achieve wire-line and wireless access synchronously. With the CSRZ-DPSK modulation, the wireless access in ONU can save RF source and the frequency of radio carrier can be controlled by OLT. The dual-wavelength fiber laser is the union light source of WDM-PON with polarization multiplexing. By the RSOA and downstream light source reusing, the ONU can save omit laser source and makes the WDM-PON to be colorless. The networking has the credible transmission property, including wireless access and fiber transmission. The networking also has excellent covering range.

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY 2014 Fourth Quarterly Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Fifield, Leonard S.; Mathur, Raj N.

2014-09-30

During the last quarter of FY 2014, the following technical progress has been made toward project milestones: 1) Autodesk, Inc. (Autodesk) has implemented a new fiber length distribution (FLD) model based on an unbreakable length assumption with Reduced Order Modeling (ROM) by the Proper Orthogonal Decomposition (POD) approach in the mid-plane, dual-domain and 3D solvers. 2) Autodesk improved the ASMI 3D solver for fiber orientation prediction using the anisotropic rotary diffusion (ARD) – reduced strain closure (RSC) model. 3) Autodesk received consultant services from Prof. C.L. Tucker at the University of Illinois on numerical simulation of fiber orientation and fibermore » length. 4) PlastiComp, Inc. (PlastiComp) suggested to Purdue University a procedure for fiber separation using an inert-gas atmosphere in the burn-off furnace. 5) Purdue University (Purdue) hosted a face-to-face project review meeting at Purdue University on August 6-7, 2014. 6) Purdue conducted fiber orientation measurements for 3 PlastiComp plaques: fast-fill 30wt% LCF/PP edged-gated, slow-fill 50wt% LCF/PP edge-gated, and slow-fill 50wt% LCF/PP center-gated plaques, and delivered the orientation data for these plaques at the selected locations (named A, B, and C) to PNNL. 7) PNNL conducted ASMI mid-plane analyses for the above PlastiComp plaques and compared the predicted fiber orientations with the measured data provided by Purdue at Locations A, B, and C on these plaques. 8) PNNL planned the project review meeting (August 6-7, 2014) with Purdue. 9) PNNL performed ASMI analyses for the Toyota complex parts with and without ribs, having different wall thicknesses, and using the PlastiComp 50wt% LCF/PP, 50wt% LCF/PA66, 30wt% LCF/PP, and 30wt% LCF/PA66 materials to provide guidance for tool design and modifications needed for molding these parts. 10) Magna Exteriors and Interiors Corp. (Magna) molded plaques from the 50% LCF/PP and 50% LCF/PA66 materials received from Plasticomp in order to extract machine purgings (purge materials) from Magna’s 200-Ton Injection Molding machine targeted to mold the complex part. 11) Toyota and Magna discussed with PNNL tool modification for molding the complex part.« less

Mechanical properties of composite materials

NASA Technical Reports Server (NTRS)

Thornton, H. Richard; Cornwell, L. R.

1993-01-01

A composite material incorporates high strength, high modulus fibers in a matrix (polymer, metal, or ceramic). The fibers may be oriented in a manner to give varying in-plane properties (longitudinal, transverse-stress, strain, and modulus of elasticity). The lay-up of the composite laminates is such that a center line of symmetry and no bending moment exist through the thickness. The laminates are tabbed, with either aluminum or fiberglass, and are ready for tensile testing. The determination of the tensile properties of resin matrix composites, reinforced by continuous fibers, is outlined in ASTM standard D 3039, Tensile Properties of Oriented Fiber Composites. The tabbed flat tensile coupons are placed into the grips of a tensile machine and load-deformation curves plotted. The load-deformation data are translated into stress-strain curves for determination of mechanical properties (ultimate tensile strength and modulus of elasticity).

Injection-Molded Long-Fiber Thermoplastic Composites: From Process Modeling to Prediction of Mechanical Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Ba Nghiep; Kunc, Vlastimil; Jin, Xiaoshi

2013-12-18

This article illustrates the predictive capabilities for long-fiber thermoplastic (LFT) composites that first simulate the injection molding of LFT structures by Autodesk® Simulation Moldflow® Insight (ASMI) to accurately predict fiber orientation and length distributions in these structures. After validating fiber orientation and length predictions against the experimental data, the predicted results are used by ASMI to compute distributions of elastic properties in the molded structures. In addition, local stress-strain responses and damage accumulation under tensile loading are predicted by an elastic-plastic damage model of EMTA-NLA, a nonlinear analysis tool implemented in ABAQUS® via user-subroutines using an incremental Eshelby-Mori-Tanaka approach. Predictedmore » stress-strain responses up to failure and damage accumulations are compared to the experimental results to validate the model.« less

Variable angle-of-incidence polarization-sensitive optical coherence tomography: its use to study the 3D collagen structure of equine articular cartilage

NASA Astrophysics Data System (ADS)

Ugryumova, Nadya; Gangnus, Sergei V.; Matcher, Stephen J.

2006-02-01

Polarization-sensitive optical coherence tomography has been used to spatially map the birefringence of equine articular cartilage. The polar orientation of the collagen fibers relative to the plane of the joint surface must be taken into account if a quantitative measurement of true birefringence is required. Using a series of images taken at different angles of illumination, we determine the fiber polar angle and true birefringence at one site on a sample of equine cartilage, on the assumption that the fibers lie within the plane of imaging. We propose a more general method based on the extended Jones matrix formalism to determine both the polar and azimuthal orientation of the collagen fibers as well as the true birefringence as functions of depth.

Optical storage networking

NASA Astrophysics Data System (ADS)

Mohr, Ulrich

2001-11-01

For efficient business continuance and backup of mission- critical data an inter-site storage network is required. Where traditional telecommunications costs are prohibitive for all but the largest organizations, there is an opportunity for regional carries to deliver an innovative storage service. This session reveals how a combination of optical networking and protocol-aware SAN gateways can provide an extended storage networking platform with the lowest cost of ownership and the highest possible degree of reliability, security and availability. Companies of every size, with mainframe and open-systems environments, can afford to use this integrated service. Three mayor applications are explained; channel extension, Network Attached Storage (NAS), Storage Area Networks (SAN) and how optical networks address the specific requirements. One advantage of DWDM is the ability for protocols such as ESCON, Fibre Channel, ATM and Gigabit Ethernet, to be transported natively and simultaneously across a single fiber pair, and the ability to multiplex many individual fiber pairs over a single pair, thereby reducing fiber cost and recovering fiber pairs already in use. An optical storage network enables a new class of service providers, Storage Service Providers (SSP) aiming to deliver value to the enterprise by managing storage, backup, replication and restoration as an outsourced service.

Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

NASA Astrophysics Data System (ADS)

Komarkova, Tereza; Fiala, Pavel; Steinbauer, Miloslav; Roubal, Zdenek

2018-02-01

Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor-sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

A parametric study of fracture toughness of fibrous composite materials

NASA Technical Reports Server (NTRS)

Poe, C. C., Jr.

1987-01-01

Impacts to fibrous composite laminates by objects with low velocities can break fibers giving crack-like damage. The damage may not extend completely through a thick laminate. The tension strength of these damage laminates is reduced much like that of cracked metals. The fracture toughness depends on fiber and matrix properties, fiber orientations, and stacking sequence. Accordingly, a parametric study was made to determine how fiber and matrix properties and fiber orientations affect fracture toughness and notch sensitivity. The values of fracture toughness were predicted from the elastic constants of the laminate and the failing strain of the fibers using a general fracture toughness parameter developed previously. For a variety of laminates, values of fracture toughness from tests of center-cracked specimens and values of residual strength from tests of thick laminates with surface cracks were compared to the predictions to give credibility to the study. In contrast to the usual behavior of metals, it is shown that both ultimate tensile strength and fracture toughness of composites can be increased without increasing notch sensitivity.

The Effect of General Statistical Fiber Misalignment on Predicted Damage Initiation in Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Aboudi, Jacob; Arnold, Steven M.

2014-01-01

A micromechanical method is employed for the prediction of unidirectional composites in which the fiber orientation can possess various statistical misalignment distributions. The method relies on the probability-weighted averaging of the appropriate concentration tensor, which is established by the micromechanical procedure. This approach provides access to the local field quantities throughout the constituents, from which initiation of damage in the composite can be predicted. In contrast, a typical macromechanical procedure can determine the effective composite elastic properties in the presence of statistical fiber misalignment, but cannot provide the local fields. Fully random fiber distribution is presented as a special case using the proposed micromechanical method. Results are given that illustrate the effects of various amounts of fiber misalignment in terms of the standard deviations of in-plane and out-of-plane misalignment angles, where normal distributions have been employed. Damage initiation envelopes, local fields, effective moduli, and strengths are predicted for polymer and ceramic matrix composites with given normal distributions of misalignment angles, as well as fully random fiber orientation.

Hybrid Fiber/Copper LAN Meets School's 25-Year Networking Requirements.

ERIC Educational Resources Information Center

Petruso, Sam; Humes, Vince

1994-01-01

Describes an innovative new curriculum being implemented at Walnut Creek Middle School (Pennsylvania) and an advanced networked computer environment that supports it now and will also meet future needs. Topics addressed include physical facilities; networking goals, both short-term and long-term; fiber-optic cable versus copper; and future…

Unusual Formation of Precursors for Crystallization of Ultra-High Performance Polypropylene and Poly(ethylene terephthalate) Fibers by Utilization of Ecologically Friendly Horizontal Isothermal Bath

NASA Astrophysics Data System (ADS)

Avci, Huseyin

The concept of production of new families of high performance polymers and engineering fibers has been reported many times in the technical literature. Such fibers have various end uses in industrial applications and exhibit the enhanced potential in the challenging areas such as ballistic, automotive, aerospace, bullet-proof vests, energy, and electronics. Since the first commercial synthesis of high polymers by Carothers and Hill, filament manufacturers have looked for ways to increase strength and fibers dimensional stability, thermal degradation resistance, etc., even at extreme conditions. Therefore, studies on the fine structure development and its relation with production conditions during the wet, dry, and melt spinning processes have received much attention by researchers to describe in detail the fundamental aspects of the fiber formation. The production of ultra-high performance fibers at relatively high throughputs by a simple method using fiber-forming polymers via developing an ecologically friendly isothermal bath (ECOB) is the first aim of this study. In this case, polypropylene (PP) was chosen as a semicrystalline thermoplastic polymer which is extensively used in industry and our daily lives. A unique, highly oriented precursor (fa = 0.60), and yet noncrystallized, undrawn fibers were obtained with superior mechanical properties. Fibrillated break, high crystalline and amorphous orientation factors of 0.95 and 0.87, respectively, demonstrate an unusual structural development after only 1.34 draw ratio for the treated fibers. The second melting peak increased 9 °C for the treated fibers, which implies a higher level of molecular ordering and thermodynamically more stable phase. After hot drawing and 1.49 draw ratio, the fibers tenacity was close to 12 g/d, the initial modulus was higher than 150 g/d, and the ultimate elongation was at a break of about 20 %. In the next phase of the research, the effects of horizontal isothermal bath (hIB)11 on the structural development and the production of ultra-high performance as-spun and drawn polypropylene (PP) filaments were investigated. Two different commercial fiber forming PP polymers were used with the melt flow rate of 4.1 and 36 g/10 min. The results demonstrate surprisingly different precursor morphologies for each type of polymer at their optimum process condition. Interestingly, the all treated fibers demonstrated the similar fiber performance having tenacity of about 7 g/d and modulus of 75 g/d for as-spun fibers. After fiber drawing with DR of 1.49, tenacity greater than 12 g/d and modulus higher than 190 g/d were observed. The mean value for the modulus after the drawing process for the high melt flow rate is about 196 g/d. The theoretical modulus of PP is 35--42 GPa17, 275-330 g/d, which demonstrates the hIB fiber's modulus performance is approaching its theoretical maximum values. A key aspect of the third section of this study was to obtain ultra-high performance poly(ethylene terephthalate) fibers (PET) by utilizing a low molecular weight polymer via hIB method. The resulted fibers showed the efficient polymer chain orientation and the highly crystalline and ordered structures. The highest tenacity of more than 8 and 10 g/d were observed for the as-spun and drawn fibers, respectively, after only 1.28 draw ratios. The significant effect of the temperature of hIB spinning system on the fibrillar structure and the precursor's formation of the as-spun fibers was demonstrated. The melting temperature increased 8.51 °C from 254.05 to 262.56 °C when untreated and treated fibers are compared. The most important contribution of this study is that all these various types of polymer precursors for crystallization with different molecular weights after the baths treatments were highly oriented, yet non-crystallized or just showed the initial stages of crystallization. By a subsequent hot drawing process with the low draw ratio (DR< 1.5), the treated fibers showed a well-developed chain orientation and highly crystallized structures with superior mechanical performance.

Burning characteristics and fiber retention of graphite/resin matrix composites

NASA Technical Reports Server (NTRS)

Bowles, K. J.

1980-01-01

Graphite fiber reinforced resin matrix composites were subjected to controlled burning conditions to determine their burning characteristics and fiber retention properties. Small samples were burned with a natural gas fired torch to study the effects of fiber orientation and structural flaws such as holes and slits that were machined into the laminates. Larger laminate samples were burned in a modified heat release rate calorimeter. Unidirectional epoxy/graphite and polyimide/graphite composites and boron powder filled samples of each of the two composite systems were burn tested. The composites were exposed to a thermal radiation of 5.3 Btu/sq ft-sec in air. Samples of each of the unfilled composite were decomposed anaerobically in the calorimeter. Weight loss data were recorded for burning and decomposition times up to thirty-five minutes. The effects of fiber orientation, flaws, and boron filler additives to the resins were evaluated. A high char forming polyimide resin was no more effective in retaining graphite fibers than a low char forming epoxy resin when burned in air. Boron powder additions to both the polyimide and the epoxy resins stabilized the chars and effectively controlled the fiber release.

Vibration control of multiferroic fibrous composite plates using active constrained layer damping

NASA Astrophysics Data System (ADS)

Kattimani, S. C.; Ray, M. C.

2018-06-01

Geometrically nonlinear vibration control of fiber reinforced magneto-electro-elastic or multiferroic fibrous composite plates using active constrained layer damping treatment has been investigated. The piezoelectric (BaTiO3) fibers are embedded in the magnetostrictive (CoFe2O4) matrix forming magneto-electro-elastic or multiferroic smart composite. A three-dimensional finite element model of such fiber reinforced magneto-electro-elastic plates integrated with the active constrained layer damping patches is developed. Influence of electro-elastic, magneto-elastic and electromagnetic coupled fields on the vibration has been studied. The Golla-Hughes-McTavish method in time domain is employed for modeling a constrained viscoelastic layer of the active constrained layer damping treatment. The von Kármán type nonlinear strain-displacement relations are incorporated for developing a three-dimensional finite element model. Effect of fiber volume fraction, fiber orientation and boundary conditions on the control of geometrically nonlinear vibration of the fiber reinforced magneto-electro-elastic plates is investigated. The performance of the active constrained layer damping treatment due to the variation of piezoelectric fiber orientation angle in the 1-3 Piezoelectric constraining layer of the active constrained layer damping treatment has also been emphasized.

Remote Spectroscopy in the Visible Using Fibers on the Optical Internet Network

ERIC Educational Resources Information Center

Ribeiro, Rafael A. S.; de Oliveira, Anderson R.; Zilio, Sergio C.

2010-01-01

The work presented here demonstrates the feasibility of using the single-mode fibers of an optical Internet network to deliver visible light between separate laboratories as a way to perform remote spectroscopy in the visible for teaching purposes. The coupling of a broadband light source into the single-mode fiber (SMF) and the characterization…

Characterizing structure connectivity correlation with the default mode network in Alzheimer's patients and normal controls

NASA Astrophysics Data System (ADS)

Guo, Jia; Xu, Peng; Song, Chao; Yao, Li; Zhao, Xiaojie

2012-03-01

Magnetic resonance diffusion tensor imaging (DTI) is a kind of effective measure to do non-invasive investigation on brain fiber structure at present. Studies of fiber tracking based on DTI showed that there was structural connection of white matter fiber among the nodes of resting-state functional network, denoting that the connection of white matter was the basis of gray matter regions in functional network. Nevertheless, relationship between these structure connectivity regions and functional network has not been clearly indicated. Moreover, research of fMRI found that activation of default mode network (DMN) in Alzheimer's disease (AD) was significantly descended, especially in hippocampus and posterior cingulated cortex (PCC). The relationship between this change of DMN activity and structural connection among functional networks needs further research. In this study, fast marching tractography (FMT) algorithm was adopted to quantitative calculate fiber connectivity value between regions, and hippocampus and PCC which were two important regions in DMN related with AD were selected to compute white matter connection region between them in elderly normal control (NC) and AD patient. The fiber connectivity value was extracted to do the correlation analysis with activity intensity of DMN. Results showed that, between PCC and hippocampus of NC, there exited region with significant high connectivity value of white matter fiber whose performance has relatively strong correlation with the activity of DMN, while there was no significant white matter connection region between them for AD patient which might be related with reduced network activation in these two regions of AD.

Growth of single-crystal YAG fiber optics.

PubMed

Nie, Craig D; Bera, Subhabrata; Harrington, James A

2016-07-11

Single-crystal YAG (Y₃Al₅O₁₂) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

RTM: Cost-effective processing of composite structures

NASA Technical Reports Server (NTRS)

Hasko, Greg; Dexter, H. Benson

1991-01-01

Resin transfer molding (RTM) is a promising method for cost effective fabrication of high strength, low weight composite structures from textile preforms. In this process, dry fibers are placed in a mold, resin is introduced either by vacuum infusion or pressure, and the part is cured. RTM has been used in many industries, including automotive, recreation, and aerospace. Each of the industries has different requirements of material strength, weight, reliability, environmental resistance, cost, and production rate. These requirements drive the selection of fibers and resins, fiber volume fractions, fiber orientations, mold design, and processing equipment. Research is made into applying RTM to primary aircraft structures which require high strength and stiffness at low density. The material requirements are discussed of various industries, along with methods of orienting and distributing fibers, mold configurations, and processing parameters. Processing and material parameters such as resin viscosity, perform compaction and permeability, and tool design concepts are discussed. Experimental methods to measure preform compaction and permeability are presented.

A theoretical investigation of soliton induced supercontinuum generation in liquid core photonic crystal fiber and dual core optical fiber

NASA Astrophysics Data System (ADS)

Porsezian, K.; Nithyanandan, K.; Vasantha Jayakantha Raja, R.; Ganapathy, R.

2013-07-01

The supercontinuum generation (SCG) in liquid core photonic crystal fiber (LCPCF) with versatile nonlinear response and the spectral broadening in dual core optical fiber is presented. The analysis is presented in two phase, phase I deals with the SCG in LCPCF with the effect of saturable nonlinearity and re-orientational nonlinearity. We identify and discuss the generic nature of the saturable nonlinearity and reorientational nonlinearity in the SCG, using suitable model. For the physical explanation, modulational instability and soliton fission techniques is implemented to investigate the impact of saturable nonlinear response and slow nonlinear response, respectively. It is observed that the saturable nonlinearity inevitably suppresses the MI and the subsequent SCG. On the other hand, the re-orientational nonlinearity contributes to the slow nonlinear response in addition to the conventional fast response due to the electronic contribution. The phase II features the exclusive investigation of the spectral broadening in the dual core optical fiber.

Extremely Elastic Wearable Carbon Nanotube Fiber Strain Sensor for Monitoring of Human Motion.

PubMed

Ryu, Seongwoo; Lee, Phillip; Chou, Jeffrey B; Xu, Ruize; Zhao, Rong; Hart, Anastasios John; Kim, Sang-Gook

2015-06-23

The increasing demand for wearable electronic devices has made the development of highly elastic strain sensors that can monitor various physical parameters an essential factor for realizing next generation electronics. Here, we report an ultrahigh stretchable and wearable device fabricated from dry-spun carbon nanotube (CNT) fibers. Stretching the highly oriented CNT fibers grown on a flexible substrate (Ecoflex) induces a constant decrease in the conductive pathways and contact areas between nanotubes depending on the stretching distance; this enables CNT fibers to behave as highly sensitive strain sensors. Owing to its unique structure and mechanism, this device can be stretched by over 900% while retaining high sensitivity, responsiveness, and durability. Furthermore, the device with biaxially oriented CNT fiber arrays shows independent cross-sensitivity, which facilitates simultaneous measurement of strains along multiple axes. We demonstrated potential applications of the proposed device, such as strain gauge, single and multiaxial detecting motion sensors. These devices can be incorporated into various motion detecting systems where their applications are limited to their strain.

Electrospun meshes possessing region-wise differences in fiber orientation, diameter, chemistry and mechanical properties for engineering bone-ligament-bone tissues.

PubMed

Samavedi, Satyavrata; Vaidya, Prasad; Gaddam, Prudhvidhar; Whittington, Abby R; Goldstein, Aaron S

2014-12-01

Although bone-patellar tendon-bone (B-PT-B) autografts are the gold standard for repair of anterior cruciate ligament ruptures, they suffer from drawbacks such as donor site morbidity and limited supply. Engineered tissues modeled after B-PT-B autografts are promising alternatives because they have the potential to regenerate connective tissue and facilitate osseointegration. Towards the long-term goal of regenerating ligaments and their bony insertions, the objective of this study was to construct 2D meshes and 3D cylindrical composite scaffolds - possessing simultaneous region-wise differences in fiber orientation, diameter, chemistry and mechanical properties - by electrospinning two different polymers from off-set spinnerets. Using a dual drum collector, 2D meshes consisting of an aligned polycaprolactone (PCL) fiber region, randomly oriented poly(lactide-co-glycolide) (PLGA) fiber region and a transition region (comprised of both PCL and PLGA fibers) were prepared, and region-wise differences were confirmed by microscopy and tensile testing. Bone marrow stromal cells (BMSCs) cultured on these meshes exhibited random orientations and low aspect ratios on the random PLGA regions, and high aspect ratios and alignment on the aligned PCL regions. Next, meshes containing an aligned PCL region flanked by two transition regions and two randomly oriented PLGA regions were prepared and processed into 3D cylindrical composite scaffolds using an interpenetrating photo-crosslinkable polyethylene glycol diacrylate hydrogel to recapitulate the shape of B-PT-B autografts. Tensile testing indicated that cylindrical composites were mechanically robust, and eventually failed due to stress concentration in the aligned PCL region. In summary, this study demonstrates a process to fabricate electrospun meshes possessing region-wise differences in properties that can elicit region-dependent cell responses, and be readily processed into scaffolds with the shape of B-PT-B autografts. © 2014 Wiley Periodicals, Inc.

Composition and structure of porcine digital flexor tendon-bone insertion tissues.

PubMed

Chandrasekaran, Sandhya; Pankow, Mark; Peters, Kara; Huang, Hsiao-Ying Shadow

2017-11-01

Tendon-bone insertion is a functionally graded tissue, transitioning from 200 MPa tensile modulus at the tendon end to 20 GPa tensile modulus at the bone, across just a few hundred micrometers. In this study, we examine the porcine digital flexor tendon insertion tissue to provide a quantitative description of its collagen orientation and mineral concentration by using Fast Fourier Transform (FFT) based image analysis and mass spectrometry, respectively. Histological results revealed uniformity in global collagen orientation at all depths, indicative of mechanical anisotropy, although at mid-depth, the highest fiber density, least amount of dispersion, and least cellular circularity were evident. Collagen orientation distribution obtained through 2D FFT of histological imaging data from fluorescent microscopy agreed with past measurements based on polarized light microscopy. Results revealed global fiber orientation across the tendon-bone insertion to be preserved along direction of physiologic tension. Gradation in the fiber distribution orientation index across the insertion was reflective of a decrease in anisotropy from the tendon to the bone. We provided elemental maps across the fibrocartilage for its organic and inorganic constituents through time-of-flight secondary ion mass spectrometry (TOF-SIMS). The apatite intensity distribution from the tendon to bone was shown to follow a linear trend, supporting past results based on Raman microprobe analysis. The merit of this study lies in the image-based simplified approach to fiber distribution quantification and in the high spatial resolution of the compositional analysis. In conjunction with the mechanical properties of the insertion tissue, fiber, and mineral distribution results for the insertion from this may potentially be incorporated into the development of a structural constitutive approach toward computational modeling. Characterizing the properties of the native insertion tissue would provide the microstructural basis for developing biomimetic scaffolds to recreate the graded morphology of a fibrocartilaginous insertion. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3050-3058, 2017. © 2017 Wiley Periodicals, Inc.

All-fiber intensity bend sensor based on photonic crystal fiber with asymmetric air-hole structure

NASA Astrophysics Data System (ADS)

Budnicki, Dawid; Szostkiewicz, Lukasz; Szymanski, Michal O.; Ostrowski, Lukasz; Holdynski, Zbigniew; Lipinski, Stanislaw; Murawski, Michal; Wojcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Pawel; Napierala, Marek; Nasilowski, Tomasz

2017-10-01

Monitoring the geometry of an moving element is a crucial task for example in robotics. The robots equipped with fiber bend sensor integrated in their arms can be a promising solution for medicine, physiotherapy and also for application in computer games. We report an all-fiber intensity bend sensor, which is based on microstructured multicore optical fiber. It allows to perform a measurement of the bending radius as well as the bending orientation. The reported solution has a special airhole structure which makes the sensor only bend-sensitive. Our solution is an intensity based sensor, which measures power transmitted along the fiber, influenced by bend. The sensor is based on a multicore fiber with the special air-hole structure that allows detection of bending orientation in range of 360°. Each core in the multicore fiber is sensitive to bend in specified direction. The principle behind sensor operation is to differentiate the confinement loss of fundamental mode propagating in each core. Thanks to received power differences one can distinguish not only bend direction but also its amplitude. Multicore fiber is designed to utilize most common light sources that operate at 1.55 μm thus ensuring high stability of operation. The sensitivity of the proposed solution is equal 29,4 dB/cm and the accuracy of bend direction for the fiber end point is up to 5 degrees for 15 cm fiber length. Such sensitivity allows to perform end point detection with millimeter precision.

Tribological dry sliding behavior of chopped carbon fiber reinforced polyetheretherketone

NASA Astrophysics Data System (ADS)

Chumaevskii, A. V.; Ivanov, A. N.; Filippov, A. V.; Rubtsov, V. E.; Kolubaev, E. A.

2017-12-01

Tribological tests on 3D printed pure polyetheretherketone and carbon fiber reinforced polyetheretherketone samples were carried out. The negative effect of carbon fiber sticking out of the matrix on wear and sliding process stability was revealed. These fibers may be too long and oriented to the worn surface in a manner that prevents their removal by wear so that the worn surface becomes irregular and the sliding process instable.

Spatial-spectral flexible optical networking: enabling switching solutions for a simplified and efficient SDM network platform

NASA Astrophysics Data System (ADS)

Tomkos, I.; Zakynthinos, P.; Klonidis, D.; Marom, D.; Sygletos, S.; Ellis, A.; Salvadori, E.; Siracusa, D.; Angelou, M.; Papastergiou, G.; Psaila, N.; Ferran, J. F.; Ben-Ezra, S.; Jimenez, F.; Fernández-Palacios, J. P.

2013-12-01

The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution.

Process for the manufacture of carbon or graphite fibers

NASA Technical Reports Server (NTRS)

Overhoff, D.; Winkler, E.; Mueller, D.

1979-01-01

Carbon or graphite fibers are manufactured by heating polyacrylonitrile fiber materials in various solutions and gases. They are characterized in that the materials are heated to temperatures from 150 to 300 C in a solution containing one or more acids from the group of carbonic acids, sulfonic acids, and/or phenols. The original molecular orientation of the fibers is preserved by the cyclization that occurs before interlacing, which gives very strong and stiff carbon or graphite fibers without additional high temperature stretching treatments.

Transversely polarized source cladding for an optical fiber

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1994-01-01

An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented transversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.

The development of a fiber optics communication network for controlling a Multidegree-Of-Freedom Serpentine Truss

NASA Astrophysics Data System (ADS)

Andrawis, Alfred S.

1994-10-01

The problem addressed by this report is the large size and heavy weight of the cable bundle, used for controlling a Multidegree-Of-Freedom Serpentine Truss Manipulator arm, which imposes limitations on the manipulator arm maneuverability. This report covers a design of an optical fiber network to replace the existing copper wire network of the Serpentine Truss Manipulator. This report proposes a fiber network design which significantly reduces the bundle size into two phases. The first phase does not require any modifications for the manipulator architecture, while the other requires major modifications. Design philosophy, hardware details and schematic diagrams are presented.

The development of a fiber optics communication network for controlling a Multidegree-Of-Freedom Serpentine Truss

NASA Technical Reports Server (NTRS)

Andrawis, Alfred S.

1994-01-01

The problem addressed by this report is the large size and heavy weight of the cable bundle, used for controlling a Multidegree-Of-Freedom Serpentine Truss Manipulator arm, which imposes limitations on the manipulator arm maneuverability. This report covers a design of an optical fiber network to replace the existing copper wire network of the Serpentine Truss Manipulator. This report proposes a fiber network design which significantly reduces the bundle size into two phases. The first phase does not require any modifications for the manipulator architecture, while the other requires major modifications. Design philosophy, hardware details and schematic diagrams are presented.

Microstructure characterization based on the type of deformed grains in cold-rolled, Cu-added, bake-hardenable steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J.S.; Kim, S.I.; Choi, S.-H., E-mail: shihoon@sunchon.ac.kr

2014-06-01

The electron backscatter diffraction technique has been used to characterize the microstructure of deformed grains in cold-rolled, Cu-added, bake-hardenable steel. A new scheme based on the kind and number of average orientations, as determined from a unique grain map of the deformed grains, was developed in order to classify deformed grains by type. The α-fiber components, γ-fiber components and random orientations, those which could not be assigned to either γ-fiber or α-fiber components, were used to define the average orientation of unique grains within individual deformed grains. The microstructures of deformed grains in as-rolled specimens were analyzed based on themore » Taylor factor, stored energy, and misorientation. The relative levels and distributions of the Taylor factor, the stored energy and the misorientation were examined in terms of the types of deformed grains. - Highlights: • We characterized the microstructure of Cu-added BH steel using EBSD. • A new scheme was developed in order to classify deformed grains by type. • Stored energy and misorientation are strongly dependent on the type of deformed grains. • Microstructure was examined in terms of the types of deformed grains.« less

Development of Engineering Data on Advanced Composite Materials

DTIC Science & Technology

1982-02-01

otherwise as in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use, or sell any...4.1 T300/V378A 138 4.5 HyE 1076J 168 4.6 G-160/6535-1 200 4.7 COMPARATIVE ENVIRONMENTAL BEHAVIOR 231 5 CONCLUSIONS 236 REFERENCES 240 APPENDICES A...Fiber Orientation 62 17 Tensile Creep Behavior of Unidirectional T300/AFRSOO Composite Laminates: 0* Fiber Orientation 64 18 Tensile Creep Behavior of

Development of an optical fiber flow velocity sensor.

PubMed

Harada, Toshio; Kamoto, Kenji; Abe, Kyutaro; Izumo, Masaki

2009-01-01

A new optical fiber flow velocity sensor was developed by using an optical fiber information network system in sewer drainage pipes. The optical fiber flow velocity sensor operates without electric power, and the signals from the sensor can be transmitted over a long distance through the telecommunication system in the optical fiber network. Field tests were conducted to check the performance of the sensor in conduits in the pumping station and sewage pond managed by the Tokyo Metropolitan Government. Test results confirmed that the velocity sensor can be used for more than six months without any trouble even in sewer drainage pipes.

Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

PubMed

Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

2016-02-10

Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

Computational Characterization of Type I collagen-based Extra-cellular Matrix

NASA Astrophysics Data System (ADS)

Liang, Long; Jones, Christopher Allen Rucksack; Lin, Daniel; Jiao, Yang; Sun, Bo

2015-03-01

A model of extracellular matrix (ECM) of collagen fibers has been built, in which cells could communicate with distant partners via fiber-mediated long-range-transmitted stress states. The ECM is modeled as a spring-like fiber network derived from skeletonized confocal microscopy data. Different local and global perturbations have been performed on the network, each followed by an optimized global Monte-Carlo (MC) energy minimization leading to the deformed network in response to the perturbations. In the optimization, a highly efficient local energy update procedure is employed and force-directed MC moves are used, which results in a convergence to the energy minimum state 20 times faster than the commonly used random displacement trial moves in MC. Further analysis and visualization of the distribution and correlation of the resulting force network reveal that local perturbations can give rise to global impacts: the force chains formed with a linear extent much further than the characteristic length scale associated with the perturbation sites and average fiber length. This behavior provides a strong evidence for our hypothesis of fiber-mediated long-range force transmission in ECM networks and the resulting long-range cell-cell mechanical signaling. ASU Seed Grant.

Designing and Integrating a Fiber Optic Network with an Existing Copper Network.

ERIC Educational Resources Information Center

Knapp, Wallace C.

The process that Catonsville Community College (Maryland) went through in moving from a copper to a fiber network is outlined. The discussion addresses the following: describing the need in real terms; building consensus for the project; gaining support by college management; justifying the need for consultant support; writing the request for…

The fiber orientation in the coronary arterial wall at physiological loading evaluated with a two-fiber constitutive model.

PubMed

van der Horst, Arjen; van den Broek, Chantal N; van de Vosse, Frans N; Rutten, Marcel C M

2012-03-01

A patient-specific mechanical description of the coronary arterial wall is indispensable for individualized diagnosis and treatment of coronary artery disease. A way to determine the artery's mechanical properties is to fit the parameters of a constitutive model to patient-specific experimental data. Clinical data, however, essentially lack information about the stress-free geometry of an artery, which is necessary for constitutive modeling. In previous research, it has been shown that a way to circumvent this problem is to impose extra modeling constraints on the parameter estimation procedure. In this study, we propose a new modeling constraint concerning the in-situ fiber orientation (β (phys)). β (phys), which is a major contributor to the arterial stress-strain behavior, was determined for porcine and human coronary arteries using a mixed numerical-experimental method. The in-situ situation was mimicked using in-vitro experiments at a physiological axial pre-stretch, in which pressure-radius and pressure-axial force were measured. A single-layered, hyperelastic, thick-walled, two-fiber material model was accurately fitted to the experimental data, enabling the computation of stress, strain, and fiber orientation. β (phys) was found to be almost equal for all vessels measured (36.4 ± 0.3)°, which theoretically can be explained using netting analysis. In further research, this finding can be used as an extra modeling constraint in parameter estimation from clinical data.

A physical layer perspective on access network sharing

NASA Astrophysics Data System (ADS)

Pfeiffer, Thomas

2015-12-01

Unlike in copper or wireless networks, there is no sharing of resources in fiber access networks yet, other than bit stream access or cable sharing, in which the fibers of a cable are let to one or multiple operators. Sharing optical resources on a single fiber among multiple operators or different services has not yet been applied. While this would allow for a better exploitation of installed infrastructures, there are operational issues which still need to be resolved, before this sharing model can be implemented in networks. Operating multiple optical systems and services over a common fiber plant, autonomously and independently from each other, can result in mutual distortions on the physical layer. These distortions will degrade the performance of the involved systems, unless precautions are taken in the infrastructure hardware to eliminate or to reduce them to an acceptable level. Moreover, the infrastructure needs to be designed such as to support different system technologies and to ensure a guaranteed quality of the end-to-end connections. In this paper, suitable means are proposed to be introduced in fiber access infrastructures that will allow for shared utilization of the fibers while safeguarding the operational needs and business interests of the involved parties.

Physics of soft hyaluronic acid-collagen type II double network gels

NASA Astrophysics Data System (ADS)

Morozova, Svetlana; Muthukumar, Murugappan

2015-03-01

Many biological hydrogels are made up of multiple interpenetrating, charged components. We study the swelling, elastic diffusion, mechanical, and optical behaviors of 100 mol% ionizable hyaluronic acid (HA) and collagen type II fiber networks. Dilute, 0.05-0.5 wt% hyaluronic acid networks are extremely sensitive to solution salt concentration, but are stable at pH above 2. When swelled in 0.1M NaCl, single-network hyaluronic acid gels follow scaling laws relevant to high salt semidilute solutions; the elastic shear modulus G' and diffusion constant D scale with the volume fraction ϕ as G' ~ϕ 9 / 4 and D ~ϕ 3 / 4 , respectively. With the addition of a collagen fiber network, we find that the hyaluronic acid network swells to suspend the rigid collagen fibers, providing extra strength to the hydrogel. Results on swelling equilibria, elasticity, and collective diffusion on these double network hydrogels will be presented.

An in silico framework to analyze the anisotropic shear wave mechanics in cardiac shear wave elastography

NASA Astrophysics Data System (ADS)

Caenen, Annette; Pernot, Mathieu; Peirlinck, Mathias; Mertens, Luc; Swillens, Abigail; Segers, Patrick

2018-04-01

Shear wave elastography (SWE) is a potential tool to non-invasively assess cardiac muscle stiffness. This study focused on the effect of the orthotropic material properties and mechanical loading on the performance of cardiac SWE, as it is known that these factors contribute to complex 3D anisotropic shear wave propagation. To investigate the specific impact of these complexities, we constructed a finite element model with an orthotropic material law subjected to different uniaxial stretches to simulate SWE in the stressed cardiac wall. Group and phase speed were analyzed in function of tissue thickness and virtual probe rotation angle. Tissue stretching increased the group and phase speed of the simulated shear wave, especially in the direction of the muscle fiber. As the model provided access to the true fiber orientation and material properties, we assessed the accuracy of two fiber orientation extraction methods based on SWE. We found a higher accuracy (but lower robustness) when extracting fiber orientations based on the location of maximal shear wave speed instead of the angle of the major axis of the ellipsoidal group speed surface. Both methods had a comparable performance for the center region of the cardiac wall, and performed less well towards the edges. Lastly, we also assessed the (theoretical) impact of pathology on shear wave physics and characterization in the model. It was found that SWE was able to detect changes in fiber orientation and material characteristics, potentially associated with cardiac pathologies such as myocardial fibrosis. Furthermore, the model showed clearly altered shear wave patterns for the fibrotic myocardium compared to the healthy myocardium, which forms an initial but promising outcome of this modeling study.

I Keep my Problems to Myself: Negative Social Network Orientation, Social Resources, and Health-Related Quality of Life in Cancer Survivors

PubMed Central

Symes, Yael; Campo, Rebecca A.; Wu, Lisa M.; Austin, Jane

2016-01-01

Background Cancer survivors treated with hematopoietic stem cell transplant rely on their social network for successful recovery. However, some survivors have negative attitudes about using social resources (negative social network orientation) that are critical for their recovery. Purpose We examined the association between survivors’ social network orientation and health-related quality of life (HRQoL) and whether it was mediated by social resources (network size, perceived support, and negative and positive support-related social exchanges). Methods In a longitudinal study, 255 survivors completed validated measures of social network orientation, HRQoL, and social resources. Hypotheses were tested using path analysis. Results More negative social network orientation predicted worse HRQoL (p < .001). This association was partially mediated by lower perceived support and more negative social exchanges. Conclusions Survivors with negative social network orientation may have poorer HRQoL in part due to deficits in several key social resources. Findings highlight a subgroup at risk for poor transplant outcomes and can guide intervention development. PMID:26693932

Short cellulose nanofribrils as reinforcement in polyvinyl alcohol fiber

Treesearch

Jun Peng; Thomas Ellingham; Ron Sabo; Lih-Sheng Turng; Craig M. Clemons

2014-01-01

Short cellulose nanofibrils (SCNF) were investigated as reinforcement for polyvinyl alcohol (PVA) fibers. SCNF were mechanically isolated from hard wood pulp after enzymatic pretreatment. Various levels of SCNF were added to an aqueous PVA solution, which was gel-spun into continuous fibers. The molecular orientation of PVA was affected by a combination of wet drawing...

Optical fiber sensors for damage analysis in aerospace materials

NASA Technical Reports Server (NTRS)

Schindler, Paul; May, Russell; Claus, Richard

1995-01-01

Under this grant, fiber optic sensors were investigated for use in the nondestructive evaluation of aging aircraft. Specifically, optical fiber sensors for detection and location of impacts on a surface, and for detection of corrosion in metals were developed. The use of neural networks was investigated for determining impact location by processing the output of a network of fiberoptic strain sensors distributed on a surface. This approach employs triangulation to determine location by comparing the arrival times at several sensors, of the acoustic signal generated by the impact. For this study, a neural network simulator running on a personal computer was used to train a network using a back-propagation algorithm. Fiber optic extrinsic Fabry-Perot interferometer (EFPI) strain sensors are attached to or embedded in the surface, so that stress waves emanating from an impact can be detected. The ability of the network to determine impact location by time-or-arrival of acoustic signals was assessed by comparing network outputs with actual experimental results using impacts on a panel instrumented with optical fiber sensors. Using the neural network to process the sensor outputs, the impact location can be inferred to centimeter range accuracy directly from the arrival time data. In addition, the network can be trained to determine impact location, regardless of material anisotropy. Results demonstrate that a back-propagation network identifies impact location for an anisotropic graphite/bismaleimide plate with the same accuracy as that for an isotropic aluminum plate. Two different approaches were investigated for the development of fiber optic sensors for corrosion detection in metals, both utilizing optical fiber sensors with metal coatings. In the first approach, an extrinsic Fabry-Perot interferometric fiber optic strain sensor was placed under tensile stress, and while in the resulting strained position, a thick coating of metal was applied. Due to an increase in the quantity of material, the sensor does not return to its original position upon removal of the applied stress, and some residual strain is maintained within the sensor element. As the metal thickness decreases due to corrosion, this strain is released, providing the sensing mechanism for corrosion detection. In the second approach, photosensitive optical fibers with long period Bragg gratings in the core were coated with metal. The Bragg gratings serve to couple core modes at discrete wavelengths to cladding modes. Since cladding modes interact with the metal coating surrounding the fiber cladding, the specific wavelengths coupled from core to cladding depend on the refractive index of the metal coating. Therefore, as the metal corrodes, the resulting change in index of the coating may be measured by measuring the change in wavelength of the coupled mode. Results demonstrate that both approaches can be successfully used to track the loss in metal coating on the optical fiber sensors due to corrosion.

Final Report for the project titled "Enabling Supernova Computations by Integrated Transport and Provisioning Methods Optimized for Dedicated Channels"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malathi Veeraraghavan

2007-10-31

A high-speed optical circuit network is one that offers users rate-guaranteed connectivity between two endpoints, unlike today’s IP-routed Internet in which the rate available to a pair of users fluctuates based on the volume of competing traffic. This particular research project advanced our understanding of circuit networks in two ways. First, transport protocols were developed for circuit networks. In a circuit network, since bandwidth resources are reserved for each circuit on an end-to-end basis (much like how a person reserves a seat on every leg of a multi-segment flight), and the sender is limited to send at the rate ofmore » the circuit, there is no possibility of congestion during data transfer. Therefore, no congestion control functions are necessary in a transport protocol designed for circuits. However, error control and flow control are still required because bits can become errored due to noise and interference even on highly reliable optical links, and receivers can, due to multitasking or other reasons, not deplete the receive buffer fast enough to keep up with the sending rate (e.g., if the receiving host is multitasking between receiving a file transfer and some other computation). In this work, we developed two transport protocols for circuits, both of which are described below. Second, this project developed techniques for internetworking different types of connection-oriented networks, which are of two types: circuit-switched or packet-switched. In circuit-switched networks, multiplexing on links is “position based,” where “position” refers to the frequency, time slot, and port (fiber), while connection-oriented packet-switched networks use packet header information to demultiplex packets and switch them from node to node. The latter are commonly referred to as virtual circuit networks. Examples of circuit networks are time-division multiplexed Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Wavelength Division Multiplexing (WDM) networks, while examples of virtual-circuit networks are MultiProtocol Label Switched (MPLS) networks and Ethernet Virtual Local Area Network (VLAN) networks. A series of new technologies have been developed to carry Ethernet VLAN tagged frames on SONET/SDH and WDM networks, such as Generic Framing Procedure (GFP) and ITU G.709, respectively. These technologies form the basis of our solution for connection-oriented internetworking. The benefit of developing such an architecture is that it allows different providers to choose different connection-oriented networking technologies for their networks, and yet be able to allow their customers to connect to those of other providers. As Metcalfe, the inventor of Ethernet, noted, the value of a network service grows exponentially with the number of endpoints to which any single endpoint can connect. Therefore internetworking solutions are key to commercial success. The technical effectiveness of our solutions was measured with proof-of-concept prototypes and experiments. These solutions were shown to be highly effective. Economic feasibility requires business case analyses that were beyond the scope of this project. The project results are beneficial to the public as they demonstrate the viability of simultaneously supporting different types of networks and data communication services much like the variety of services available for the transportation of people and goods. For example, Fedex service offers a deadline based delivery while the USPS offers basic package delivery service. Similarly, a circuit network can offer a deadline based delivery of a data file while the IP-routed network offers only basic delivery service with no guarantees. Two project Web sites, 13 publications, 7 software programs, 21 presentations resulted from this work. This report provides the complete list of publications, software programs and presentations. As for student education and training (human resources), this DOE project, along with an NSF project, jointly supported two postdoctoral fellowships, three PhDs, three Masters, and two undergraduate students. Specifically, two of the Masters students were directly funded on this DOE project.« less

In situ investigation of deformation mechanisms in magnesium-based metal matrix composites

NASA Astrophysics Data System (ADS)

Farkas, Gergely; Choe, Heeman; Máthis, Kristián; Száraz, Zoltán; Noh, Yoonsook; Trojanová, Zuzanka; Minárik, Peter

2015-07-01

We studied the effect of short fibers on the mechanical properties of a magnesium alloy. In particular, deformation mechanisms in a Mg-Al-Sr alloy reinforced with short alumina fibers were studied in situ using neutron diffraction and acoustic emission methods. The fibers' plane orientation with respect to the loading axis was found to be a key parameter, which influences the acting deformation processes, such as twinning or dislocation slip. Furthermore, the twinning activity was much more significant in samples with parallel fiber plane orientation, which was confirmed by both acoustic emission and electron backscattering diffraction results. Neutron diffraction was also used to assist in analyzing the acoustic emission and electron backscattering diffraction results. The simultaneous application of the two in situ methods, neutron diffraction and acoustic emission, was found to be beneficial for obtaining complementary datasets about the twinning and dislocation slip in the magnesium alloys and composites used in this study.

The Effect of Fiber Architecture on Matrix Cracking in Sic/sic Cmc's

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.

2005-01-01

Applications incorporating silicon carbide fiber reinforced silicon carbide matrix composites (CMC's) will require a wide range of fiber architectures in order to fabricate complex shape. The stress-strain response of a given SiC/SiC system for different architectures and orientations will be required in order to design and effectively life-model future components. The mechanism for non-linear stress-strain behavior in CMC's is the formation and propagation of bridged-matrix cracks throughout the composite. A considerable amount of understanding has been achieved for the stress-dependent matrix cracking behavior of SiC fiber reinforced SiC matrix systems containing melt-infiltrated Si. This presentation will outline the effect of 2D and 3D architectures and orientation on stress-dependent matrix-cracking and how this information can be used to model material behavior and serve as the starting point foe mechanistic-based life-models.

Finite element analysis and optimization of composite structures

NASA Technical Reports Server (NTRS)

Thomsen, Jan

1990-01-01

Linearly elastic fiber reinforced composite discs and laminates in plane stress with variable local orientation and concentration of one or two fiber fields embedded in the matrix material, are considered. The thicknesses and the domain of the discs or laminates are assumed to be given, together with prescribed boundary conditions and in-plane loading along the edge. The problem under study consists in determining throughout the structural domain the optimum orientations and concentrations of the fiber fields in such a way as to maximize the integral stiffness of the composite disc or laminate under the seven loading. Minimization of the integral stiffness can also be performed. The optimization is performed subject to a prescribed bound on the total cost or weight of the composite that for given unit cost factors or specific weights determines the amounts of fiber and matrix materials in the structure. Examples are presented.

Quantitative regulation of bone-mimetic, oriented collagen/apatite matrix structure depends on the degree of osteoblast alignment on oriented collagen substrates.

PubMed

Matsugaki, Aira; Isobe, Yoshihiro; Saku, Taro; Nakano, Takayoshi

2015-02-01

Bone tissue has a specific anisotropic morphology derived from collagen fiber alignment and the related apatite crystal orientation as a bone quality index. However, the precise mechanism of cellular regulation of the crystallographic orientation of apatite has not been clarified. In this study, anisotropic construction of cell-produced mineralized matrix in vitro was established by initiating organized cellular alignment and subsequent oriented bone-like matrix (collagen/apatite) production. The oriented collagen substrates with three anisotropic levels were prepared by a hydrodynamic method. Primary osteoblasts were cultured on the fabricated substrates until mineralized matrix formation is confirmed. Osteoblast alignment was successfully regulated by the level of substrate collagen orientation, with preferential alignment along the direction of the collagen fibers. Notably, both fibrous orientation of newly synthesized collagen matrix and c-axis of produced apatite crystals showed preferential orientation along the cell direction. Because the degree of anisotropy of the deposited apatite crystals showed dependency on the directional distribution of osteoblasts cultured on the oriented collagen substrates, the cell orientation determines the crystallographic anisotropy of produced apatite crystals. To the best of our knowledge, this is the first report demonstrating that bone tissue anisotropy, even the alignment of apatite crystals, is controllable by varying the degree of osteoblast alignment via regulating the level of substrate orientation. © 2014 Wiley Periodicals, Inc.

Optical chaos and hybrid WDM/TDM based large capacity quasi-distributed sensing network with real-time fiber fault monitoring.

PubMed

Luo, Yiyang; Xia, Li; Xu, Zhilin; Yu, Can; Sun, Qizhen; Li, Wei; Huang, Di; Liu, Deming

2015-02-09

An optical chaos and hybrid wavelength division multiplexing/time division multiplexing (WDM/TDM) based large capacity quasi-distributed sensing network with real-time fiber fault monitoring is proposed. Chirped fiber Bragg grating (CFBG) intensity demodulation is adopted to improve the dynamic range of the measurements. Compared with the traditional sensing interrogation methods in time, radio frequency and optical wavelength domains, the measurand sensing and the precise locating of the proposed sensing network can be simultaneously interrogated by the relative amplitude change (RAC) and the time delay of the correlation peak in the cross-correlation spectrum. Assisted with the WDM/TDM technology, hundreds of sensing units could be potentially multiplexed in the multiple sensing fiber lines. Based on the proof-of-concept experiment for axial strain measurement with three sensing fiber lines, the strain sensitivity up to 0.14% RAC/με and the precise locating of the sensors are achieved. Significantly, real-time fiber fault monitoring in the three sensing fiber lines is also implemented with a spatial resolution of 2.8 cm.

Simultaneous transmission of accurate time, stable frequency, data, and sensor system over one fiber with ITU 100 GHz grid

NASA Astrophysics Data System (ADS)

Horvath, Tomas; Munster, Petr; Vojtech, Josef; Velc, Radek; Oujezsky, Vaclav

2018-01-01

Optical fiber is the most used medium for current telecommunication networks. Besides data transmissions, special advanced applications like accurate time or stable frequency transmissions are more common, especially in research and education networks. On the other hand, new applications like distributed sensing are in ISP's interest because e.g. such sensing allows new service: protection of fiber infrastructure. Transmission of all applications in a single fiber can be very cost efficient but it is necessary to evaluate possible interaction before real application and deploying the service, especially if standard 100 GHz grid is considered. We performed laboratory measurement of simultaneous transmission of 100 G data based on DP-QPSK modulation format, accurate time, stable frequency and sensing system based on phase sensitive OTDR through two types of optical fibers, G.655 and G.653. These fibers are less common than G.652 fiber but thanks to their slightly higher nonlinear character, there are suitable for simulation of the worst case which can arise in a real network.

Oriented nanofibers embedded in a polymer matrix

NASA Technical Reports Server (NTRS)

Barrera, Enrique V. (Inventor); Lozano, Karen (Inventor); Rodriguez-Macias, Fernando J. (Inventor); Chibante, Luis Paulo Felipe (Inventor); Stewart, David Harris (Inventor)

2011-01-01

A method of forming a composite of embedded nanofibers in a polymer matrix is disclosed. The method includes incorporating nanofibers in a plastic matrix forming agglomerates, and uniformly distributing the nanofibers by exposing the agglomerates to hydrodynamic stresses. The hydrodynamic said stresses force the agglomerates to break apart. In combination or additionally elongational flow is used to achieve small diameters and alignment. A nanofiber reinforced polymer composite system is disclosed. The system includes a plurality of nanofibers that are embedded in polymer matrices in micron size fibers. A method for producing nanotube continuous fibers is disclosed. Nanofibers are fibrils with diameters of 100 nm, multiwall nanotubes, single wall nanotubes and their various functionalized and derivatized forms. The method includes mixing a nanofiber in a polymer; and inducing an orientation of the nanofibers that enables the nanofibers to be used to enhance mechanical, thermal and electrical properties. Orientation is induced by high shear mixing and elongational flow, singly or in combination. The polymer may be removed from said nanofibers, leaving micron size fibers of aligned nanofibers.

Flow and dispersion in anisotropic porous media: A lattice-Boltzmann study

NASA Astrophysics Data System (ADS)

Maggiolo, D.; Picano, F.; Guarnieri, M.

2016-10-01

Given their capability of spreading active chemical species and collecting electricity, porous media made of carbon fibers are extensively used as diffusion layers in energy storage systems, such as redox flow batteries. In spite of this, the dispersion dynamics of species inside porous media is still not well understood and often lends itself to different interpretations. Actually, the microscopic design of efficient porous media, which can potentially and effectively improve the performances of flow batteries, is still an open challenge. The present study aims to investigate the effect of fibrous media micro-structure on dispersion, in particular the effect of fiber orientation on drag and dispersion dynamics. Several lattice-Boltzmann simulations of flows through differently oriented fibrous media coupled with Lagrangian simulations of particle tracers have been performed. Results show that orienting fibers preferentially along the streamwise direction minimizes the drag and maximizes the dispersion, which is the most desirable condition for diffusion layers in flow batteries' applications.

Mechanical properties of electrospun bilayer fibrous membranes as potential scaffolds for tissue engineering.

PubMed

Pu, Juan; Komvopoulos, Kyriakos

2014-06-01

Bilayer fibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning, using a parallel-disk mandrel configuration that resulted in the sequential deposition of a layer with fibers aligned across the two parallel disks and a layer with randomly oriented fibers, both layers deposited in a single process step. Membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, bilayer membranes exhibited higher porosity than single-layer membranes consisting of randomly oriented fibers fabricated with a solid-drum collector. However, despite their higher porosity, bilayer membranes demonstrated generally higher elastic modulus, yield strength and toughness than single-layer membranes with random fibers. Bilayer membrane deformation at relatively high strain rates comprised multiple abrupt microfracture events characterized by discontinuous fiber breakage. Bilayer membrane elongation yielded excessive necking of the layer with random fibers and remarkable fiber stretching (on the order of 400%) in the layer with fibers aligned in the stress direction. In addition, fibers in both layers exhibited multiple localized necking, attributed to the nonuniform distribution of crystalline phases in the fibrillar structure. The high membrane porosity, good mechanical properties, and good biocompatibility and biodegradability of PLLA (demonstrated in previous studies) make the present bilayer membranes good scaffold candidates for a wide range of tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The use of biomaterials for cell function enhancement: acceleration of fibroblast migration and promotion of stem cell proliferation

NASA Astrophysics Data System (ADS)

Qin, Sisi

Wound healing and tissue regeneration proceed via fibroblast migration along three dimensional scaffolds composed of fibers with different diameters, spacing, and junction angles. In order to understand how each of these factors influences fibroblast migration, a technique for preparation of three dimensional fibrillar scaffolds was developed where the fiber diameters and the angles between adjacent fiber layers could be precisely controlled. In order to study the en-mass migration process, the agarose droplet method was chosen since it enabled accurate determinations of the dependence of the migration speed, focal adhesion distribution, and nuclear deformation on the fiber structures. Results showed that on oriented single fiber layers, if the fiber diameters exceeded 1microm, large focal adhesion complexes formed in a linear arrangement along the fiber axis and cell motion was highly correlated. For fibers 1microm or less, some cell alignment along the fiber direction was measured, but no correlation between the distribution of focal adhesion points and fiber orientation was found. On multi layered scaffolds the focal adhesion sites were found to concentrate at the junction points and the migration speed followed a parabolic function with a distinct minimum at 35°. When compared to fibroblasts plated on 90° fibers, fibroblasts plated on 30° fibers showed a decrease of 25% in the degree of nuclear deformation and an increase of 25% in the number of focal adhesion sites, indicating that cell migration speed was correlated to the angle and distance of approach to the junction point. The time dependence of the migration velocity on oriented fibers was measured for four days and compared to the value measured on flat surfaces. After the initial 24 hour incubation period, the cells on both the 8microm fibers and flat surfaces migrated with a similar speed. During the next three days the migration speed for the cells on the fibrillar surfaces doubled in magnitude, while remained constant for the cells on the flat surfaces. The increased speed on the 8microm fiber surfaces could be correlated with a 20% increase in the nuclear deformation, and a decrease around 30% in the number of focal adhesion during the same observation period. RNA expression of Myosin IIA, a protein which complexes to the actin and is responsible for exertion of traction forces during migration was not upregulated during this process. On the other hand, histochemical staining of Myosin IIA showed that the protein had re-organized into large fibers which spanned the length of the cells. Observation of the cell morphology indicated that a new mode of motion had been established. Rather than the classical retraction of the cytoplasm followed by center of mass translation, which was observed on the flat surfaces, the cells were now moving by a contractile motion around the nucleus similar to that found in muscular motion. This mode was found to be more efficient when undergoing oriented motion. In addition to orientation, surface mechanics are also important in the tissue regeneration process. This study demonstrated that mechanical factors are important for the maintenance of pluripotency and control of proliferation rates. CD34+ hematopoietic stem cells (HSCs) were transduced with ICD (intracellular domain)-Notch and plated on gelatin hydrogels, whose moduli were controlled by the crosslinking ratio. On the softer hydrogel, a synergy was achieved which resulted in more than a five-fold increase in proliferation and a four-fold increase in the preservation of stemness, while HSCs maintained their ability to differentiate into multiple blood cell lineages. These results point the way for achieving clinically significant expansion of human HSCs.

Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

NASA Astrophysics Data System (ADS)

Gaudino, Roberto; Giuliano, Romeo; Mazzenga, Franco; Valcarenghi, Luca; Vatalaro, Francesco

2014-05-01

This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.

Recent developments in photonic networking components for space applications

NASA Astrophysics Data System (ADS)

Parkerson, James P.; Gorman, Lanitia; Thamer, Robert; Chalfant, Charles H.; Hull, Anthony; Orlando, Fred J., Jr.

2003-07-01

Industrial, NASA, and DoD spacecraft designers have recognized the advantages of using fiber optic components and networks for their internal satellite data handling needs. Among the benefits are the total elimination of cable-to-cable and box-to-box EMI; significant size, weight and power reduction; greater on-orbit and integration and test flexibility and significantly lower integration and test costs. Additionally, intra-satellite data rates of 1 to 10 Gbps appear to be an absolute requirement for a number of advanced systems planned for development in the next few years. The only practical way to support these data rates is with fiber optics. Space Photonics and the University of Arkansas have developed fiber optic components (FireFiberTM) and networks that are designed specifically to meet these on-board, high data rate needs using NASA approved materials, packaging processes, and approved radiation tolerant devices. This paper will discuss recent developments in photonic components for spaceborne networks.

The high temperature creep behavior of oxides and oxide fibers

NASA Technical Reports Server (NTRS)

Jones, Linda E.; Tressler, Richard E.

1991-01-01

A thorough review of the literature was conducted on the high-temperature creep behavior of single and polycrystalline oxides which potentially could serve as fiber reinforcements in ceramics or metal matrix applications. Sapphire when oriented with the basal plane perpendicular to the fiber axis (c-axis oriented) is highly creep resistant at temperatures in excess of 1600 C and applied loads of 100 MPa and higher. Pyramidal slip is preferentially activated in sapphire under these conditions and steady-state creep rates in the range of 10(exp -7) to 10 (exp -8)/s were reported. Data on the creep resistance of polycrystalline beryllia suggest that C-axiz oriented single crystal beryllia may be a viable candidate as a fiber reinforcement material; however, the issure of fabricability and moisture sensitivity must be addressed for this material. Yttrium aluminum garnet (YAG) also appears to be a fiber candidate material having a high resistance to creep which is due to it's complex crystal structure and high Peierl resistance. The high creep resistance of garnet suggests that there may be other complex ternary oxides such as single crystal mullite which may also be candidate materials for fiber reinforcements. Finally, CVD and single crystal SiC, although not oxides, do possess a high resistance to creep in the temperature range between 1550 and 1850 C and under stresses of 110 to 220 MPa. From a review of the literature, it appears that for high creep resistant applications sapphire, silicon carbide, yttrium aluminum garnet, mullite, and beryllia are desirable candidate materials which require further investigation.

Development Of Fiber Optics For Passenger Car Applications

NASA Astrophysics Data System (ADS)

Steele, R. E.; Schmitt, H. J.

1987-12-01

The benefits of fiber optics for telecommunications and Local Area Networks (LANs) are well documented. The benefits to passenger car applications are not as clearly defined. This paper examines the differences between Telecommunications, LAN, and automotive point to point and network applications. Current production automotive applications of optics and fiber optics, automotive data communications trends, and both functional and non-functional requirements and constraints will be described.

Low Loss Graded Index Polymer Optical Fiber for Local Networking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Claus, Richard Otto

The objective of this Department of Energy SBIR program has been to develop technology for the advancement of advanced computing systems. NanoSonic worked with two subcontractors, the Polymicro Division of Molex, a U.S.-based manufacturer of specialized optical fiber and fiber components, and Virginia Tech, a research university involved through the Global Environment for Network Innovations (GENI) program in high-speed computer networking research. NanoSonic developed a patented molecular-level self-assembly process to manufacture polymer-based optical fibers in a way similar to the modified chemical vapor deposition (MCVD) approach typically used to make glass optical fibers. Although polymer fiber has a higher attenuationmore » per unit length than glass fiber, short connectorized polymer fiber jumpers offer significant cost savings over their glass counterparts, particularly due to the potential use of low-cost plastic fiber connectors. As part of the SBIR commercialization process, NanoSonic exclusively licensed this technology to a large ($100B+ market cap) U.S.-based manufacturing conglomerate near the end of the first year of the Phase II program. With this base technology developed and licensed, NanoSonic then worked with Polymicro to address secondary program goals of using related but not conflicting production methods to enhance the performance of other specialty optical fiber products and components, and Virginia Tech continued its evaluation of developed polymer fibers in its network infrastructure system on the university campus. We also report our current understanding of the observation during the Phase I program of quantum conductance and partial quantum conductance in metal-insulator-metal (MIM) devices. Such conductance behavior may be modeled as singlemode behavior in one-dimensional electrically conducting waveguides, similar in principle to singlemode optical propagation in dielectric fiber waveguides. Although NanoSonic has not licensed any of the additional technology developed during the second year of the program, several proprietary discussions with major materials companies are underway as of the conclusion of Phase II.« less

Evaluation of omniweave reinforcement for composite fabrication

NASA Technical Reports Server (NTRS)

Belman, R.; Edighoffer, H.; Fenton, R.; Lowe, D.; Wexler, M.

1971-01-01

Molded composites made from type-2 Morganite and/or boron are suitable for structural skins. Layered-in-depth omniweave construction yields higher in-plane strength characteristics than fiber-pitch angle construction, and strength and moduli data vary with fiber orientation.

Testing and reference model analysis of FTTH system

NASA Astrophysics Data System (ADS)

Feng, Xiancheng; Cui, Wanlong; Chen, Ying

2009-08-01

With rapid development of Internet and broadband access network, the technologies of xDSL, FTTx+LAN , WLAN have more applications, new network service emerges in endless stream, especially the increase of network game, meeting TV, video on demand, etc. FTTH supports all present and future service with enormous bandwidth, including traditional telecommunication service, traditional data service and traditional TV service, and the future digital TV and VOD. With huge bandwidth of FTTH, it wins the final solution of broadband network, becomes the final goal of development of optical access network.. Fiber to the Home (FTTH) will be the goal of telecommunications cable broadband access. In accordance with the development trend of telecommunication services, to enhance the capacity of integrated access network, to achieve triple-play (voice, data, image), based on the existing optical Fiber to the curb (FTTC), Fiber To The Zone (FTTZ), Fiber to the Building (FTTB) user optical cable network, the optical fiber can extend to the FTTH system of end-user by using EPON technology. The article first introduced the basic components of FTTH system; and then explain the reference model and reference point for testing of the FTTH system; Finally, by testing connection diagram, the testing process, expected results, primarily analyze SNI Interface Testing, PON interface testing, Ethernet performance testing, UNI interface testing, Ethernet functional testing, PON functional testing, equipment functional testing, telephone functional testing, operational support capability testing and so on testing of FTTH system. ...

Convergence of broadband optical and wireless access networks

NASA Astrophysics Data System (ADS)

Chang, Gee-Kung; Jia, Zhensheng; Chien, Hung-Chang; Chowdhury, Arshad; Hsueh, Yu-Ting; Yu, Jianjun

2009-01-01

This paper describes convergence of optical and wireless access networks for delivering high-bandwidth integrated services over optical fiber and air links. Several key system technologies are proposed and experimentally demonstrated. We report here, for the first ever, a campus-wide field trial demonstration of radio-over-fiber (RoF) system transmitting uncompressed standard-definition (SD) high-definition (HD) real-time video contents, carried by 2.4-GHz radio and 60- GHz millimeter-wave signals, respectively, over 2.5-km standard single mode fiber (SMF-28) through the campus fiber network at Georgia Institute of Technology (GT). In addition, subsystem technologies of Base Station and wireless tranceivers operated at 60 GHz for real-time video distribution have been developed and tested.

Neural network configuration and efficiency underlies individual differences in spatial orientation ability.

PubMed

Arnold, Aiden E G F; Protzner, Andrea B; Bray, Signe; Levy, Richard M; Iaria, Giuseppe

2014-02-01

Spatial orientation is a complex cognitive process requiring the integration of information processed in a distributed system of brain regions. Current models on the neural basis of spatial orientation are based primarily on the functional role of single brain regions, with limited understanding of how interaction among these brain regions relates to behavior. In this study, we investigated two sources of variability in the neural networks that support spatial orientation--network configuration and efficiency--and assessed whether variability in these topological properties relates to individual differences in orientation accuracy. Participants with higher accuracy were shown to express greater activity in the right supramarginal gyrus, the right precentral cortex, and the left hippocampus, over and above a core network engaged by the whole group. Additionally, high-performing individuals had increased levels of global efficiency within a resting-state network composed of brain regions engaged during orientation and increased levels of node centrality in the right supramarginal gyrus, the right primary motor cortex, and the left hippocampus. These results indicate that individual differences in the configuration of task-related networks and their efficiency measured at rest relate to the ability to spatially orient. Our findings advance systems neuroscience models of orientation and navigation by providing insight into the role of functional integration in shaping orientation behavior.

Research on the application of softswitch in FTTH

NASA Astrophysics Data System (ADS)

Rui, Yang; Hua, Yan Xian

2005-11-01

Fiber to the home (FTTH) is the technology orientation that people have continuously pursued and explored for 20 years, and it is beginning to make significant strides in the field of high-speed broadband access to the Internet. Due to the carriers' competition, the price of optical devices reduced gradually, FTTH develops very quickly. With the emergence of next generation network (NGN), softswitch plays an important role in the evolvement from PSTN to NGN. The combination of FTTH and softswitch can solve many problems in FTTH applications, which guarantees the evolvement from the existing network to NGN and provides service functions to meet the further requirements of various carriers and customers. This paper mainly introduces the application of softswitch in FTTH, outlines the developing background of FTTH and softswitch, and discusses the voice bearing solution based on FTTH. At last it focuses on the key problems and solutions of the application with the example of the implementation of voice service.

A comparison of the bromination dynamics of various carbon and graphite fibers

NASA Technical Reports Server (NTRS)

Gaier, James R.

1987-01-01

The electrical resistance of four grades of pitch-based graphite fibers and three experimental organic vapor-derived fibers was determined in situ during bromination and subsequent exposure to ambient laboratory air. The results show that the least graphitic pitch-based fiber does not brominate significantly, and that bromination and debrominaton reactions proceed much slower for vapor-derived fibers than for pitch-based ones. It is suggested that this decreased reacton rate is primarily due to the differences in graphene plane orientation between the fiber types. The results also imply that the vapor-derived and pitch-based fibers produce true intercalation compounds.

Characterization of fiber diameter using image analysis

NASA Astrophysics Data System (ADS)

Baheti, S.; Tunak, M.

2017-10-01

Due to high surface area and porosity, the applications of nanofibers have increased in recent years. In the production process, determination of average fiber diameter and fiber orientation is crucial for quality assessment. The objective of present study was to compare the relative performance of different methods discussed in literature for estimation of fiber diameter. In this work, the existing automated fiber diameter analysis software packages available in literature were developed and validated based on simulated images of known fiber diameter. Finally, all methods were compared for their reliable and accurate estimation of fiber diameter in electro spun nanofiber membranes based on obtained mean and standard deviation.

Mean Green operators of deformable fiber networks embedded in a compliant matrix and property estimates

NASA Astrophysics Data System (ADS)

Franciosi, Patrick; Spagnuolo, Mario; Salman, Oguz Umut

2018-04-01

Composites comprising included phases in a continuous matrix constitute a huge class of meta-materials, whose effective properties, whether they be mechanical, physical or coupled, can be selectively optimized by using appropriate phase arrangements and architectures. An important subclass is represented by "network-reinforced matrices," say those materials in which one or more of the embedded phases are co-continuous with the matrix in one or more directions. In this article, we present a method to study effective properties of simple such structures from which more complex ones can be accessible. Effective properties are shown, in the framework of linear elasticity, estimable by using the global mean Green operator for the entire embedded fiber network which is by definition through sample spanning. This network operator is obtained from one of infinite planar alignments of infinite fibers, which the network can be seen as an interpenetrated set of, with the fiber interactions being fully accounted for in the alignments. The mean operator of such alignments is given in exact closed form for isotropic elastic-like or dielectric-like matrices. We first exemplify how these operators relevantly provide, from classic homogenization frameworks, effective properties in the case of 1D fiber bundles embedded in an isotropic elastic-like medium. It is also shown that using infinite patterns with fully interacting elements over their whole influence range at any element concentration suppresses the dilute approximation limit of these frameworks. We finally present a construction method for a global operator of fiber networks described as interpenetrated such bundles.

Three-mode mode-division-multiplexing passive optical network over 12-km low mode-crosstalk FMF using all-fiber mode MUX/DEMUX

NASA Astrophysics Data System (ADS)

Ren, Fang; Li, Juhao; Wu, Zhongying; Hu, Tao; Yu, Jinyi; Mo, Qi; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

2017-01-01

We propose three-mode mode-division-multiplexing passive optical network (MDM-PON) based on low mode-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). The FMF with step-index profile is designed and fabricated for effectively three-independent-spatial-mode transmission and low mode-crosstalk for MDM-PON transmission. The all-fiber mode MUX/DEMUX are composed of cascaded mode selective couplers (MSCs), which simultaneously multiplex or demultiplex multiple modes. Based on the low mode-crosstalk of the FMF and all-fiber mode MUX/DEMUX, each optical network unit (ONU) communicates with the optical line terminal (OLT) independently utilizing a different optical linearly polarized (LP) spatial mode in MDM-PON system. We experimentally demonstrate MDM-PON transmission of three independent-spatial-modes over 12-km FMF with 10-Gb/s optical on-off keying (OOK) signal and direct detection.

Charge transport in the electrospun nanofiber composite membrane's three-dimensional fibrous structure

NASA Astrophysics Data System (ADS)

DeGostin, Matthew B.; Peracchio, Aldo A.; Myles, Timothy D.; Cassenti, Brice N.; Chiu, Wilson K. S.

2016-03-01

In this paper, a Fiber Network (FN) ion transport model is developed to simulate the three-dimensional fibrous microstructural morphology that results from the electrospinning membrane fabrication process. This model is able to approximate fiber layering within a membrane as well as membrane swelling due to water uptake. The discrete random fiber networks representing membranes are converted to resistor networks and solved for current flow and ionic conductivity. Model predictions are validated by comparison with experimental conductivity data from electrospun anion exchange membranes (AEM) and proton exchange membranes (PEM) for fuel cells as well as existing theories. The model is capable of predicting in-plane and thru-plane conductivity and takes into account detailed membrane characteristics, such as volume fraction, fiber diameter, fiber conductivity, and membrane layering, and as such may be used as a tool for advanced electrode design.

Design and implementation of interface units for high speed fiber optics local area networks and broadband integrated services digital networks

NASA Technical Reports Server (NTRS)

Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph

1990-01-01

The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.

Bringing a Network-Oriented Approach to Domestic Violence Services: A Focus Group Exploration of Promising Practices.

PubMed

Goodman, Lisa A; Banyard, Victoria; Woulfe, Julie; Ash, Sarah; Mattern, Grace

2016-01-01

Despite powerful evidence that informal social support contributes to survivors' safety and well-being, mainstream domestic violence (DV) programs have not developed comprehensive models for helping isolated survivors re-engage with these networks. Although many advocates use network-oriented strategies informally, they often do so without resources, funding, or training. This qualitative focus group study explored advocates' use and perceptions of network-oriented strategies. Advocates working in a range of DV programs across one state described the importance of network-oriented work and articulated its five dimensions, including helping survivors build their capacity to form healthy relationships, identify helpful and harmful network members, re-engage with existing networks, develop new relationships, and respond more effectively to network members. © The Author(s) 2015.

Nerve Fiber Activation During Peripheral Nerve Field Stimulation: Importance of Electrode Orientation and Estimation of Area of Paresthesia.

PubMed

Frahm, Ken Steffen; Hennings, Kristian; Vera-Portocarrero, Louis; Wacnik, Paul W; Mørch, Carsten Dahl

2016-04-01

Low back pain is one of the indications for using peripheral nerve field stimulation (PNFS). However, the effect of PNFS varies between patients; several stimulation parameters have not been investigated in depth, such as orientation of the nerve fiber in relation to the electrode. While placing the electrode parallel to the nerve fiber may give lower activation thresholds, anodal blocking may occur when the propagating action potential passes an anode. A finite element model was used to simulate the extracellular potential during PNFS. This was combined with an active cable model of Aβ and Aδ nerve fibers. It was investigated how the angle between the nerve fiber and electrode affected the nerve activation and whether anodal blocking could occur. Finally, the area of paresthesia was estimated and compared with any concomitant Aδ fiber activation. The lowest threshold was found when nerve and electrode were in parallel, and that anodal blocking did not appear to occur during PNFS. The activation of Aβ fibers was within therapeutic range (<10V) of PNFS; however, within this range, Aδ fiber activation also may occur. The combined area of activated Aβ fibers (paresthesia) was at least two times larger than Aδ fibers for similar stimulation intensities. No evidence of anodal blocking was observed in this PNFS model. The thresholds were lowest when the nerves and electrodes were parallel; thus, it may be relevant to investigate the overall position of the target nerve fibers prior to electrode placement. © 2015 International Neuromodulation Society.

Longitudinal development of cortical thickness, folding, and fiber density networks in the first 2 years of life.

PubMed

Nie, Jingxin; Li, Gang; Wang, Li; Shi, Feng; Lin, Weili; Gilmore, John H; Shen, Dinggang

2014-08-01

Quantitatively characterizing the development of cortical anatomical networks during the early stage of life plays an important role in revealing the relationship between cortical structural connection and high-level functional development. The development of correlation networks of cortical-thickness, cortical folding, and fiber-density is systematically analyzed in this article to study the relationship between different anatomical properties during the first 2 years of life. Specifically, longitudinal MR images of 73 healthy subjects from birth to 2 year old are used. For each subject at each time point, its measures of cortical thickness, cortical folding, and fiber density are projected to its cortical surface that has been partitioned into 78 cortical regions. Then, the correlation matrices for cortical thickness, cortical folding, and fiber density at each time point can be constructed, respectively, by computing the inter-regional Pearson correlation coefficient (of any pair of ROIs) across all 73 subjects. Finally, the presence/absence pattern (i.e., binary pattern) of the connection network is constructed from each inter-regional correlation matrix, and its statistical and anatomical properties are adopted to analyze the longitudinal development of anatomical networks. The results show that the development of anatomical network could be characterized differently by using different anatomical properties (i.e., using cortical thickness, cortical folding, or fiber density). Copyright © 2013 Wiley Periodicals, Inc.

Design of a Phase /Doppler Light-Scattering System for Measurement of Small-Diameter Glass Fibers During Fiberglass Manufacturing

NASA Astrophysics Data System (ADS)

Schaub, Scott A.; Naqwi, Amir A.; Harding, Foster L.

1998-01-01

We present fundamental studies examining the design of a phase /Doppler laser light-scattering system applicable to on-line measurements of small-diameter ( <15 m) fibers during fiberglass manufacturing. We first discuss off-line diameter measurement techniques currently used in the fiberglass industry and outline the limitations and problems associated with these methods. For the phase /Doppler design study we have developed a theoretical computer model for the response of the measurement system to cylindrical fibers, which is based on electromagnetic scattering theory. The model, valid for arbitrary fiber diameters and hardware configurations, generates simulated detector output as a function of time for a finite absorbing, cylindrical fiber oriented perpendicular to the two incident laser beams. Results of experimental measurements are presented, confirming predictions of the theoretical model. Parametric studies have also been conducted using the computer model to identify experimental arrangements that provide linear phase -diameter relationships for small-diameter fibers, within the measurement constraints imposed by the fiberglass production environment. The effect of variations in optical properties of the glass as well as fiber orientation effects are discussed. Through this research we have identified phase /Doppler arrangements that we expect to have future applications in the fiberglass industry for on-line diameter monitoring and process control.

Design of a phase/doppler light-scattering system for measurement of small-diameter glass fibers during fiberglass manufacturing.

PubMed

Schaub, S A; Naqwi, A A; Harding, F L

1998-01-20

We present fundamental studies examining the design of a phase/Doppler laser light-scattering system applicable to on-line measurements of small-diameter (<15 mum) fibers during fiberglass manufacturing. We first discuss off-line diameter measurement techniques currently used in the fiberglass industry and outline the limitations and problems associated with these methods. For the phase/Doppler design study we have developed a theoretical computer model for the response of the measurement system to cylindrical fibers, which is based on electromagnetic scattering theory. The model, valid for arbitrary fiber diameters and hardware configurations, generates simulated detector output as a function of time for a finite absorbing, cylindrical fiber oriented perpendicular to the two incident laser beams. Results of experimental measurements are presented, confirming predictions of the theoretical model. Parametric studies have also been conducted using the computer model to identify experimental arrangements that provide linear phase-diameter relationships for small-diameter fibers, within the measurement constraints imposed by the fiberglass production environment. The effect of variations in optical properties of the glass as well as fiber orientation effects are discussed. Through this research we have identified phase/Doppler arrangements that we expect to have future applications in the fiberglass industry for on-line diameter monitoring and process control.

Gaussian Curvature Directs Stress Fiber Orientation and Cell Migration.

PubMed

Bade, Nathan D; Xu, Tina; Kamien, Randall D; Assoian, Richard K; Stebe, Kathleen J

2018-03-27

We show that substrates with nonzero Gaussian curvature influence the organization of stress fibers and direct the migration of cells. To study the role of Gaussian curvature, we developed a sphere-with-skirt surface in which a positive Gaussian curvature spherical cap is seamlessly surrounded by a negative Gaussian curvature draping skirt, both with principal radii similar to cell-length scales. We find significant reconfiguration of two subpopulations of stress fibers when fibroblasts are exposed to these curvatures. Apical stress fibers in cells on skirts align in the radial direction and avoid bending by forming chords across the concave gap, whereas basal stress fibers bend along the convex direction. Cell migration is also strongly influenced by the Gaussian curvature. Real-time imaging shows that cells migrating on skirts repolarize to establish a leading edge in the azimuthal direction. Thereafter, they migrate in that direction. This behavior is notably different from migration on planar surfaces, in which cells typically migrate in the same direction as the apical stress fiber orientation. Thus, this platform reveals that nonzero Gaussian curvature not only affects the positioning of cells and alignment of stress fiber subpopulations but also directs migration in a manner fundamentally distinct from that of migration on planar surfaces. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Single-mode fiber systems for deep space communication network

NASA Technical Reports Server (NTRS)

Lutes, G.

1982-01-01

The present investigation is concerned with the development of single-mode optical fiber distribution systems. It is pointed out that single-mode fibers represent potentially a superior medium for the distribution of frequency and timing reference signals and wideband (400 MHz) IF signals. In this connection, single-mode fibers have the potential to improve the capability and precision of NASA's Deep Space Network (DSN). Attention is given to problems related to precise time synchronization throughout the DSN, questions regarding the selection of a transmission medium, and the function of the distribution systems, taking into account specific improvements possible by an employment of single-mode fibers.

Coherent optical frequency transfer over 50-km physical distance using a 120-km-long installed telecom fiber network.

PubMed

Musha, Mitsuru; Hong, Feng-Lei; Nakagawa, Ken'ichi; Ueda, Ken-ichi

2008-10-13

Optical frequency at 1542 nm was coherently transferred over a 120-km-long installed telecom fiber network between two cities (Tsukuba and Tokyo) in Japan separated by more than 50 km. The phase noise induced by the fiber length fluctuations was actively reduced by using a fiber stretcher and an acousto-optic modulator. The fractional frequency instability of the one-way transmitted light was reduced down to less than 8.0 x 10(-16) at an averaging time of 1s, which is limited by the theoretical limit deduced from the length and the intrinsic noise of the fiber.

Impact of z-direction fiber orientation on performance of commercial and laboratory linerboards

Treesearch

David W. Vahey; John M. Considine; Roland Gleisner; Alan Rudie; Sabine Rolland du Roscoat; Jean-Francis Bloch

2009-01-01

Fibers tilted in z-direction by hydraulic forces associated with rushing or dragging the sheet can bond multiple strata together, resulting in improved out-of-plane shear strengths. Tilted fibers are difficult to identify microscopically; however, their presence can result in different measurements of Scott internal bond when tests are carried out in the two opposing...

Apparatus and method for combining light from two or more fibers into a single fiber

DOEpatents

Klingsporn, Paul Edward

2007-02-20

An apparatus and method for combining light signals carried on a plurality of input fibers onto a single receiving fiber with a high degree of efficiency. The apparatus broadly comprises the receiving fiber and a plurality of input fiber-lens assemblies, with each fiber lens assembly including an input fiber; a collimating lens interposed between the input fiber and the receiving fiber and adapted to collimate the light signal; and a focusing lens interposed between the collimating lens and the receiving fiber and adapted to focus the collimated light signal onto the face of the receiving fiber. The components of each fiber-lens assembly are oriented along an optic axis that is inclined relative to the receiving fiber, with the inclination angle depending at least in part on the input fiber's numerical aperture and the focal lengths and diameters of the collimating and focusing lenses.

Apparatus and method for combining light from two or more fibers into a single fiber

DOEpatents

Klingsporn, Paul Edward

2006-03-14

An apparatus and method for combining light signals carried on a plurality of input fibers onto a single receiving fiber with a high degree of efficiency. The apparatus broadly comprises the receiving fiber and a plurality of input fiber-lens assemblies, with each fiber lens assembly including an input fiber; a collimating lens interposed between the input fiber and the receiving fiber and adapted to collimate the light signal; and a focusing lens interposed between the collimating lens and the receiving fiber and adapted to focus the collimated light signal onto the face of the receiving fiber. The components of each fiber-lens assembly are oriented along an optic axis that is inclined relative to the receiving fiber, with the inclination angle depending at least in part on the input fiber's numerical aperture and the focal lengths and diameters of the collimating and focusing lenses.

Modeling of short fiber reinforced injection moulded composite

NASA Astrophysics Data System (ADS)

Kulkarni, A.; Aswini, N.; Dandekar, C. R.; Makhe, S.

2012-09-01

A micromechanics based finite element model (FEM) is developed to facilitate the design of a new production quality fiber reinforced plastic injection molded part. The composite part under study is composed of a polyetheretherketone (PEEK) matrix reinforced with 30% by volume fraction of short carbon fibers. The constitutive material models are obtained by using micromechanics based homogenization theories. The analysis is carried out by successfully coupling two commercial codes, Moldflow and ANSYS. Moldflow software is used to predict the fiber orientation by considering the flow kinetics and molding parameters. Material models are inputted into the commercial software ANSYS as per the predicted fiber orientation and the structural analysis is carried out. Thus in the present approach a coupling between two commercial codes namely Moldflow and ANSYS has been established to enable the analysis of the short fiber reinforced injection moulded composite parts. The load-deflection curve is obtained based on three constitutive material model namely an isotropy, transversely isotropy and orthotropy. Average values of the predicted quantities are compared to experimental results, obtaining a good correlation. In this manner, the coupled Moldflow-ANSYS model successfully predicts the load deflection curve of a composite injection molded part.

Manifold parametrization of the left ventricle for a statistical modelling of its complete anatomy

NASA Astrophysics Data System (ADS)

Gil, D.; Garcia-Barnes, J.; Hernández-Sabate, A.; Marti, E.

2010-03-01

Distortion of Left Ventricle (LV) external anatomy is related to some dysfunctions, such as hypertrophy. The architecture of myocardial fibers determines LV electromechanical activation patterns as well as mechanics. Thus, their joined modelling would allow the design of specific interventions (such as peacemaker implantation and LV remodelling) and therapies (such as resynchronization). On one hand, accurate modelling of external anatomy requires either a dense sampling or a continuous infinite dimensional approach, which requires non-Euclidean statistics. On the other hand, computation of fiber models requires statistics on Riemannian spaces. Most approaches compute separate statistical models for external anatomy and fibers architecture. In this work we propose a general mathematical framework based on differential geometry concepts for computing a statistical model including, both, external and fiber anatomy. Our framework provides a continuous approach to external anatomy supporting standard statistics. We also provide a straightforward formula for the computation of the Riemannian fiber statistics. We have applied our methodology to the computation of complete anatomical atlas of canine hearts from diffusion tensor studies. The orientation of fibers over the average external geometry agrees with the segmental description of orientations reported in the literature.

Characterization of a space orbited incoherent fiber optic bundle

NASA Technical Reports Server (NTRS)

Dewalt, Stephen A.; Taylor, Edward W.

1993-01-01

The results of a study performed to determine the effects of adverse space environments on a bundle of over 1800 optical fibers orbited for 69 months are reported. Experimental results are presented on an incoherent fiber optic bundle oriented in low Earth orbit aboard the Long Duration Exposure Facility (LDEF) satellite as part of the Space Environment Effects Experiment (M0006). Measurements were performed to determine if space induced radiation effects changed the fiber bundle characteristics. Data demonstrating the success of light transmitting fibers to withstand the adverse space environment are presented.

Optical fiber-fault surveillance for passive optical networks in S-band operation window

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Chi, Sien

2005-07-01

An S-band (1470 to 1520 nm) fiber laser scheme, which uses multiple fiber Bragg grating (FBG) elements as feedback elements on each passive branch, is proposed and described for in-service fault identification in passive optical networks (PONs). By tuning a wavelength selective filter located within the laser cavity over a gain bandwidth, the fiber-fault of each branch can be monitored without affecting the in-service channels. In our experiment, an S-band four-branch monitoring tree-structured PON system is demonstrated and investigated experimentally.

Optical fiber-fault surveillance for passive optical networks in S-band operation window.

PubMed

Yeh, Chien-Hung; Chi, Sien

2005-07-11

An S-band (1470 to 1520 nm) fiber laser scheme, which uses multiple fiber Bragg grating (FBG) elements as feedback elements on each passive branch, is proposed and described for in-service fault identification in passive optical networks (PONs). By tuning a wavelength selective filter located within the laser cavity over a gain bandwidth, the fiber-fault of each branch can be monitored without affecting the in-service channels. In our experiment, an S-band four-branch monitoring tree-structured PON system is demonstrated and investigated experimentally.

Quantum cryptography and applications in the optical fiber network

NASA Astrophysics Data System (ADS)

Luo, Yuhui

2005-09-01

Quantum cryptography, as part of quantum information and communications, can provide absolute security for information transmission because it is established on the fundamental laws of quantum theory, such as the principle of uncertainty, No-cloning theorem and quantum entanglement. In this thesis research, a novel scheme to implement quantum key distribution based on multiphoton entanglement with a new protocol is proposed. Its advantages are: a larger information capacity can be obtained with a longer transmission distance and the detection of multiple photons is easier than that of a single photon. The security and attacks pertaining to such a system are also studied. Next, a quantum key distribution over wavelength division multiplexed (WDM) optical fiber networks is realized. Quantum key distribution in networks is a long-standing problem for practical applications. Here we combine quantum cryptography and WDM to solve this problem because WDM technology is universally deployed in the current and next generation fiber networks. The ultimate target is to deploy quantum key distribution over commercial networks. The problems arising from the networks are also studied in this part. Then quantum key distribution in multi-access networks using wavelength routing technology is investigated in this research. For the first time, quantum cryptography for multiple individually targeted users has been successfully implemented in sharp contrast to that using the indiscriminating broadcasting structure. It overcomes the shortcoming that every user in the network can acquire the quantum key signals intended to be exchanged between only two users. Furthermore, a more efficient scheme of quantum key distribution is adopted, hence resulting in a higher key rate. Lastly, a quantum random number generator based on quantum optics has been experimentally demonstrated. This device is a key component for quantum key distribution as it can create truly random numbers, which is an essential requirement to perform quantum key distribution. This new generator is composed of a single optical fiber coupler with fiber pigtails, which can be easily used in optical fiber communications.

Liquid crystalline polymers

NASA Technical Reports Server (NTRS)

1990-01-01

The remarkable mechanical properties and thermal stability of fibers fabricated from liquid crystalline polymers (LCPs) have led to the use of these materials in structural applications where weight savings are critical. Advances in processing of LCPs could permit the incorporation of these polymers into other than uniaxial designs and extend their utility into new areas such as nonlinear optical devices. However, the unique feature of LCPs (intrinsic orientation order) is itself problematic, and current understanding of processing with control of orientation falls short of allowing manipulation of macroscopic orientation (except for the case of uniaxial fibers). The current and desirable characteristics of LCPs are reviewed and specific problems are identified along with issues that must be addressed so that advances in the use of these unique polymers can be expedited.

The preferential orientation and lattice misfit of the directionally solidified Fe-Al-Ta eutectic composite

NASA Astrophysics Data System (ADS)

Cui, Chunjuan; Wang, Pei; Yang, Meng; Wen, Yagang; Ren, Chiqiang; Wang, Songyuan

2018-01-01

Fe-Al intermetallic compound has been paid more attentions recently in many fields such as aeronautic, aerospace, automobile, energy and chemical engineering, and so on. In this paper Fe-Al-Ta eutectic was prepared by a modified Bridgman directional solidification technique, and it is found that microstructure of the Fe-Al-Ta eutectic alloy transforms from the broken-lamellar eutectic to cellular eutectic with the increase of the solidification rate. In the cellular eutectic structure, the fibers are parallel to each other within the same grain, but some fibers are deviated from the original orientation at the grain boundaries. To study the crystallographic orientation relationship (OR) between the two phases, the preferential orientation of the Fe-Al-Ta eutectic alloy at the different solidification rates was studied by Selected Area Electron Diffraction (SAED). Moreover, the lattice misfit between Fe2Ta(Al) Laves phase and Fe(Al,Ta) matrix phase was calculated.

Evaluation of Workpiece Temperature during Drilling of GLARE Fiber Metal Laminates Using Infrared Techniques: Effect of Cutting Parameters, Fiber Orientation and Spray Mist Application.

PubMed

Giasin, Khaled; Ayvar-Soberanis, Sabino

2016-07-28

The rise in cutting temperatures during the machining process can influence the final quality of the machined part. The impact of cutting temperatures is more critical when machining composite-metal stacks and fiber metal laminates due to the stacking nature of those hybrids which subjects the composite to heat from direct contact with metallic part of the stack and the evacuated hot chips. In this paper, the workpiece surface temperature of two grades of fiber metal laminates commercially know as GLARE is investigated. An experimental study was carried out using thermocouples and infrared thermography to determine the emissivity of the upper, lower and side surfaces of GLARE laminates. In addition, infrared thermography was used to determine the maximum temperature of the bottom surface of machined holes during drilling GLARE under dry and minimum quantity lubrication (MQL) cooling conditions under different cutting parameters. The results showed that during the machining process, the workpiece surface temperature increased with the increase in feed rate and fiber orientation influenced the developed temperature in the laminate.

Evaluation of Workpiece Temperature during Drilling of GLARE Fiber Metal Laminates Using Infrared Techniques: Effect of Cutting Parameters, Fiber Orientation and Spray Mist Application

PubMed Central

Giasin, Khaled; Ayvar-Soberanis, Sabino

2016-01-01

The rise in cutting temperatures during the machining process can influence the final quality of the machined part. The impact of cutting temperatures is more critical when machining composite-metal stacks and fiber metal laminates due to the stacking nature of those hybrids which subjects the composite to heat from direct contact with metallic part of the stack and the evacuated hot chips. In this paper, the workpiece surface temperature of two grades of fiber metal laminates commercially know as GLARE is investigated. An experimental study was carried out using thermocouples and infrared thermography to determine the emissivity of the upper, lower and side surfaces of GLARE laminates. In addition, infrared thermography was used to determine the maximum temperature of the bottom surface of machined holes during drilling GLARE under dry and minimum quantity lubrication (MQL) cooling conditions under different cutting parameters. The results showed that during the machining process, the workpiece surface temperature increased with the increase in feed rate and fiber orientation influenced the developed temperature in the laminate. PMID:28773757

Characterization of Damage in Triaxial Braid Composites Under Tensile Loading

NASA Technical Reports Server (NTRS)

Littell, Justin D.; Binienda, Wieslaw K.; Roberts, Gary D.; Goldberg, Robert K.

2009-01-01

Carbon fiber composites utilizing flattened, large tow yarns in woven or braided forms are being used in many aerospace applications. Their complex fiber architecture and large unit cell size present challenges in both understanding deformation processes and measuring reliable material properties. This report examines composites made using flattened 12k and 24k standard modulus carbon fiber yarns in a 0 /+60 /-60 triaxial braid architecture. Standard straight-sided tensile coupons are tested with the 0 axial braid fibers either parallel with or perpendicular to the applied tensile load (axial or transverse tensile test, respectively). Nonuniform surface strain resulting from the triaxial braid architecture is examined using photogrammetry. Local regions of high strain concentration are examined to identify where failure initiates and to determine the local strain at the time of initiation. Splitting within fiber bundles is the first failure mode observed at low to intermediate strains. For axial tensile tests splitting is primarily in the 60 bias fibers, which were oriented 60 to the applied load. At higher strains, out-of-plane deformation associated with localized delamination between fiber bundles or damage within fiber bundles is observed. For transverse tensile tests, the splitting is primarily in the 0 axial fibers, which were oriented transverse to the applied load. The initiation and accumulation of local damage causes the global transverse stress-strain curves to become nonlinear and causes failure to occur at a reduced ultimate strain. Extensive delamination at the specimen edges is also observed.

Recent developments in optical fibers and how defense, security, and sensing can benefit

NASA Astrophysics Data System (ADS)

Régnier, E.; Burov, E.; Pastouret, A.; Boivin, D.; Kuyt, G.; Gooijer, F.; Bergonzo, A.; Berkers, A.; Signoret, P.; Troussellier, L.; Storaasli, O.; Nouchi, P.

2009-05-01

For many years, fiber manufacturers have devoted research efforts to develop fibers with improved radiation resistance, keeping the same advantages and basic properties as standard fibers. Today, both single-mode (SMF) and multimode (MMF) RadHard (for Radiation-Hardened) fibers are available; some of them are MIL-49291 certified and are already used, for example in military applications and at the Large Hadron Collider (LHC) in CERN or in certain nuclear power plants. These RadHard fibers can be easily connected to standard optical networks for classical data transfer or they can also be used for command control. Using some specific properties (Raman or Brillouin scattering, Bragg gratings...), such fibers can also be used as distributed sensing (temperature or strain sensors, etc) in radiation environments. At least, optical fibers can also be used for signal amplification, either in telecom networks, or in fiber lasers. This last category of fibers is called active fibers, in opposition to passive fibers used for simple signal transmission. Draka has also recently worked to improve the radiation-resistance of these active fibers, so that Draka can now offer RadHard fibers for full optical systems.

Towards Noise Tomography and Passive Monitoring Using Distributed Acoustic Sensing

NASA Astrophysics Data System (ADS)

Paitz, P.; Fichtner, A.

2017-12-01

Distributed Acoustic Sensing (DAS) has the potential to revolutionize the field of seismic data acquisition. Thanks to their cost-effectiveness, fiber-optic cables may have the capability of complementing conventional geophones and seismometers by filling a niche of applications utilizing large amounts of data. Therefore, DAS may serve as an additional tool to investigate the internal structure of the Earth and its changes over time; on scales ranging from hydrocarbon or geothermal reservoirs to the entire globe. An additional potential may be in the existence of large fibre networks deployed already for telecommunication purposes. These networks that already exist today could serve as distributed seismic antennas. We investigate theoretically how ambient noise tomography may be used with DAS data. For this we extend the theory of seismic interferometry to the measurement of strain. With numerical, 2D finite-difference examples we investigate the impact of source and receiver effects. We study the effect of heterogeneous source distributions and the cable orientation by assessing similarities and differences to the Green's function. We also compare the obtained interferometric waveforms from strain interferometry to displacement interferometric wave fields obtained with existing methods. Intermediate results show that the obtained interferometric waveforms can be connected to the Green's Functions and provide consistent information about the propagation medium. These simulations will be extended to reservoir scale subsurface structures. Future work will include the application of the theory to real-data examples. The presented research depicts the early stage of a combination of theoretical investigations, numerical simulations and real-world data applications. We will therefore evaluate the potentials and shortcomings of DAS in reservoir monitoring and seismology at the current state, with a long-term vision of global seismic tomography utilizing DAS data from existing fiber-optic cable networks.

Subcortical orientation biases explain orientation selectivity of visual cortical cells.

PubMed

Vidyasagar, Trichur R; Jayakumar, Jaikishan; Lloyd, Errol; Levichkina, Ekaterina V

2015-04-01

The primary visual cortex of carnivores and primates shows an orderly progression of domains of neurons that are selective to a particular orientation of visual stimuli such as bars and gratings. We recorded from single-thalamic afferent fibers that terminate in these domains to address the issue whether the orientation sensitivity of these fibers could form the basis of the remarkable orientation selectivity exhibited by most cortical cells. We first performed optical imaging of intrinsic signals to obtain a map of orientation domains on the dorsal aspect of the anaesthetized cat's area 17. After confirming using electrophysiological recordings the orientation preferences of single neurons within one or two domains in each animal, we pharmacologically silenced the cortex to leave only the afferent terminals active. The inactivation of cortical neurons was achieved by the superfusion of either kainic acid or muscimol. Responses of single geniculate afferents were then recorded by the use of high impedance electrodes. We found that the orientation preferences of the afferents matched closely with those of the cells in the orientation domains that they terminated in (Pearson's r = 0.633, n = 22, P = 0.002). This suggests a possible subcortical origin for cortical orientation selectivity. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Functional imaging of skeletal muscle fiber in different physiological states by second harmonic generation

NASA Astrophysics Data System (ADS)

Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Tesi, C.; Piroddi, N.; Poggesi, C.; Castiglioni, C.; Milani, A.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

2007-07-01

The intrinsically ordered arrays of proteins in skeletal muscle allows imaging of this tissue by Second Harmonic Generation (SHG). Biochemical and colocalization studies have gathered an increasing wealth of clues for the attribution of the molecular origin of the muscle SHG signal to the motor protein myosin. Thus, SHG represents a potentially very powerful tool in the investigation of structural dynamics occurring in muscle during active production of force. A full characterization of the polarization-dependence of the SHG signal represents a very selective information on the orientation of the emitting proteins and their dynamics during contraction, provided that different physiological states of muscle (relaxed, rigor and active) exhibit distinct patterns of SHG polarization dependence. Here polarization data are obtained from single frog muscle fibers at rest and during isometric contraction and interpreted, by means of a model, in terms of an average orientation of the SHG emitters which are structured with a cylindrical symmetry about the fiber axis. Optimizing the setup for accurate polarization measurements with SHG, we developed a line scan imaging method allowing measurement of SHG polarization curves in different physiological states. We demonstrate that muscle fiber displays a measurable variation of the orientation of SHG emitters with the transition from rest to isometric contraction.

Multiscale finite element modeling of sheet molding compound (SMC) composite structure based on stochastic mesostructure reconstruction

DOE PAGES

Chen, Zhangxing; Huang, Tianyu; Shao, Yimin; ...

2018-03-15

Predicting the mechanical behavior of the chopped carbon fiber Sheet Molding Compound (SMC) due to spatial variations in local material properties is critical for the structural performance analysis but is computationally challenging. Such spatial variations are induced by the material flow in the compression molding process. In this work, a new multiscale SMC modeling framework and the associated computational techniques are developed to provide accurate and efficient predictions of SMC mechanical performance. The proposed multiscale modeling framework contains three modules. First, a stochastic algorithm for 3D chip-packing reconstruction is developed to efficiently generate the SMC mesoscale Representative Volume Element (RVE)more » model for Finite Element Analysis (FEA). A new fiber orientation tensor recovery function is embedded in the reconstruction algorithm to match reconstructions with the target characteristics of fiber orientation distribution. Second, a metamodeling module is established to improve the computational efficiency by creating the surrogates of mesoscale analyses. Third, the macroscale behaviors are predicted by an efficient multiscale model, in which the spatially varying material properties are obtained based on the local fiber orientation tensors. Our approach is further validated through experiments at both meso- and macro-scales, such as tensile tests assisted by Digital Image Correlation (DIC) and mesostructure imaging.« less

A novel fibrous duct structure discovered in the brain meninges by using polarized light microscopy

NASA Astrophysics Data System (ADS)

Nam, Min-Ho; Jung, Sharon Jiyoon; Soh, Kwang-Sup; Lim, Jaekwan; Seo, Eunseok; Lim, Jun; Baek, Miok; Lee, Sang Joon

2016-05-01

We have previously reported the discovery of a novel fibrous structure (NFS) consisting of unidirectionally arranged collagen fibers in the spinal pia mater. Due to its unique structure, it was easily detected using polarized light microscopy. In the current study, we describe the discovery of a similar NFS in the brain meninges of rats by using polarized light microscopy. This NFS is located beneath the superior sagittal sinus. Initially, we systemically analyzed the polarization properties of the NFS. The change in the light intensity of the NFS, with respect to the polarization angle, was eight times greater than that of blood vessels, showing that the collagen fibers are oriented in a particular direction with almost perfect parallelism (0.99). The orientation angle of the polarization ellipse confirmed the orientation of the collagen fibers in the NFS. Histological studies further confirmed that the unidirectionally arranged collagen fibers were responsible for this distinct polarization property. Surprisingly, X-ray microtomography and 3D confocal imaging revealed that the NFS contains within it a duct structure, a putative primo vessel. In conclusion, we report a NFS in the brain meninges, detected by using polarized light microscopy, that provides space for a putative primo vessel, not a blood vessel.

Multiscale finite element modeling of sheet molding compound (SMC) composite structure based on stochastic mesostructure reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zhangxing; Huang, Tianyu; Shao, Yimin

Predicting the mechanical behavior of the chopped carbon fiber Sheet Molding Compound (SMC) due to spatial variations in local material properties is critical for the structural performance analysis but is computationally challenging. Such spatial variations are induced by the material flow in the compression molding process. In this work, a new multiscale SMC modeling framework and the associated computational techniques are developed to provide accurate and efficient predictions of SMC mechanical performance. The proposed multiscale modeling framework contains three modules. First, a stochastic algorithm for 3D chip-packing reconstruction is developed to efficiently generate the SMC mesoscale Representative Volume Element (RVE)more » model for Finite Element Analysis (FEA). A new fiber orientation tensor recovery function is embedded in the reconstruction algorithm to match reconstructions with the target characteristics of fiber orientation distribution. Second, a metamodeling module is established to improve the computational efficiency by creating the surrogates of mesoscale analyses. Third, the macroscale behaviors are predicted by an efficient multiscale model, in which the spatially varying material properties are obtained based on the local fiber orientation tensors. Our approach is further validated through experiments at both meso- and macro-scales, such as tensile tests assisted by Digital Image Correlation (DIC) and mesostructure imaging.« less

Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

PubMed Central

Braaf, Boy; Vermeer, Koenraad A.; de Groot, Mattijs; Vienola, Kari V.; de Boer, Johannes F.

2014-01-01

In polarization-sensitive optical coherence tomography (PS-OCT) the use of single-mode fibers causes unpredictable polarization distortions which can result in increased noise levels and erroneous changes in calculated polarization parameters. In the current paper this problem is addressed by a new Jones matrix analysis method that measures and corrects system polarization distortions as a function of wavenumber by spectral analysis of the sample surface polarization state and deeper located birefringent tissue structures. This method was implemented on a passive-component depth-multiplexed swept-source PS-OCT system at 1040 nm which was theoretically modeled using Jones matrix calculus. High-resolution B-scan images are presented of the double-pass phase retardation, diattenuation, and relative optic axis orientation to show the benefits of the new analysis method for in vivo imaging of the human retina. The correction of system polarization distortions yielded reduced phase retardation noise, and better estimates of the diattenuation and the relative optic axis orientation in weakly birefringent tissues. The clinical potential of the system is shown by en face visualization of the phase retardation and optic axis orientation of the retinal nerve fiber layer in a healthy volunteer and a glaucoma patient with nerve fiber loss. PMID:25136498

Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering.

PubMed

Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

2007-08-01

Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.

Perspectives and limitations of QKD integration in metropolitan area networks.

PubMed

Aleksic, Slavisa; Hipp, Florian; Winkler, Dominic; Poppe, Andreas; Schrenk, Bernhard; Franzl, Gerald

2015-04-20

Quantum key distribution (QKD) systems have already reached a reasonable level of maturity. However, a smooth integration and a wide adoption of commercial QKD systems in metropolitan area networks has still remained challenging because of technical and economical obstacles. Mainly the need for dedicated fibers and the strong dependence of the secret key rate on both loss budget and background noise in the quantum channel hinder a practical, flexible and robust implementation of QKD in current and next-generation optical metro networks. In this paper, we discuss these obstacles and present approaches to share existing fiber infrastructures among quantum and classical channels. Particularly, a proposal for a smooth integration of QKD in optical metro networks, which implies removing spurious background photons caused by optical transmitters, amplifiers and nonlinear effects in fibers, is presented and discussed. We determine and characterize impairments on quantum channels caused by many classical telecom channels at practically used power levels coexisting within the same fiber. Extensive experimental results are presented and indicate that a practical integration of QKD in conventional optical metro networks is possible.

Investigation on harsh environmental effects on polymer fiber optic link for aircraft systems

NASA Astrophysics Data System (ADS)

Cherian, Sandy; Spangenberg, Holger; Caspary, Reinhard

2014-09-01

To integrate polymer fiber based physical layer for avionic data network, it is necessary to understand the impact and cause of harsh environments on polymer fiber optic components and harnesses. Since temperature and vibration have a significant influence, we investigate the variation in optical transmittance and monitor the endurance of different types of connector and splices under extreme aircraft environments. Presently, there is no specific aerospace standard for the application of polymer fiber and components in the aircraft data network. Therefore, in the paper we examine and define the thermal cycling and vibration measurement set up and methods to evaluate the performance capability of the physical layer of the data network. Some of the interesting results observed during the measurements are also presented.

Low-cost fused taper polymer optical fiber (LFT-POF) splitters for environmental and home-networking solution

NASA Astrophysics Data System (ADS)

Supian, L. S.; Ab-Rahman, Mohammad Syuhaimi; Harun, Mohd Hazwan; Gunab, Hadi; Sulaiman, Malik; Naim, Nani Fadzlina

2017-08-01

In visible optical communication over the multimode PMMA fibers, the overall cost of optical network can be reduced by deploying economical splitters for distributing the optical data signals from a point to multipoint in transmission network. The low-cost splitters shall have two main characteristics; good uniformity and high power efficiency. The most cost-effective and environmental friendly optical splitter having those characteristics have been developed. The device material is 100% purely based on the multimode step-index PMMA Polymer Optical Fiber (POF). The region which all fibers merged as single fiber is called as fused-taper POF. This ensures that all fibers are melted and fused properly. The results for uniformity and power efficiency of all splitters have been revealed by injecting red LED transmitter with 650 nm wavelength into input port while each end of output fibers measured by optical power meter. Final analysis shows our fused-taper splitter has low excess loss 0.53 dB and each of the output port has low insertion loss, which the average value is below 7 dB. In addition, the splitter has good uniformity that is 32:37:31% in which it is suitably used for demultiplexer fabrication.

Topological Edge Modes in Active Mikado Networks

NASA Astrophysics Data System (ADS)

Zhou, Di; Zhang, Leyou; Mao, Xiaoming

Mechanical properties of disordered fiber networks are not only important in understanding a broad range of natural (such as the cytoskeleton and the extracellular matrix) and manmade materials (such as aerogels and porous media) but also exhibit interesting and rich physics. In this talk, we discuss how topological floppy edge modes can emerge from these fiber networks as a result of active driving. It is known that straight fibers in a network carries a state of self-stress and bears a bulk floppy mode. We find that, interestingly, by driving the network with a tiny perturbation, the bulk modes evolve into edge modes. We introduce a new transfer matrix formulation that can be applied to this strongly disordered system, to characterize the topological edge modes. We also discuss possible implications of these edge modes in biological processes. NSF-DMR-1609051.

Planning Multitechnology Access Networks with Performance Constraints

NASA Astrophysics Data System (ADS)

Chamberland, Steven

Considering the number of access network technologies and the investment needed for the “last mile” of a solution, in today’s highly competitive markets, planning tools are crucial for the service providers to optimize the network costs and accelerate the planning process. In this paper, we propose to tackle the problem of planning access networks composed of four technologies/architectures: the digital subscriber line (xDSL) technologies deployed directly from the central office (CO), the fiber-to-the-node (FTTN), the fiber-to-the-micro-node (FTTn) and the fiber-to-the-premises (FTTP). A mathematical programming model is proposed for this planning problem that is solved using a commercial implementation of the branch-and-bound algorithm. Next, a detailed access network planning example is presented followed by a systematic set of experiments designed to assess the performance of the proposed approach.

And They're Off! The Race to Fiber Optics.

ERIC Educational Resources Information Center

Lewis, Joan E.

1993-01-01

Describes fiber optic technology and discusses its use in distance learning and educational reform. Highlights include the quality of communications transmission systems; costs; Federal Communications Commission rules and regulations; cable television; networks, including the National Research and Education Network (NREN); government versus…

Adjustable Optical-Fiber Attenuator

NASA Technical Reports Server (NTRS)

Buzzetti, Mike F.

1994-01-01

Adjustable fiber-optic attenuator utilizes bending loss to reduce strength of light transmitted along it. Attenuator functions without introducing measurable back-reflection or insertion loss. Relatively insensitive to vibration and changes in temperature. Potential applications include cable television, telephone networks, other signal-distribution networks, and laboratory instrumentation.

Method and Apparatus of Multiplexing and Acquiring Data from Multiple Optical Fibers Using a Single Data Channel of an Optical Frequency-Domain Reflectometry (OFDR) System

NASA Technical Reports Server (NTRS)

Parker, Jr., Allen R (Inventor); Chan, Hon Man (Inventor); Piazza, Anthony (Nino) (Inventor); Richards, William Lance (Inventor)

2014-01-01

A method and system for multiplexing a network of parallel fiber Bragg grating (FBG) sensor-fibers to a single acquisition channel of a closed Michelson interferometer system via a fiber splitter by distinguishing each branch of fiber sensors in the spatial domain. On each branch of the splitter, the fibers have a specific pre-determined length, effectively separating each branch of fiber sensors spatially. In the spatial domain the fiber branches are seen as part of one acquisition channel on the interrogation system. However, the FBG-reference arm beat frequency information for each fiber is retained. Since the beat frequency is generated between the reference arm, the effective fiber length of each successive branch includes the entire length of the preceding branch. The multiple branches are seen as one fiber having three segments where the segments can be resolved. This greatly simplifies optical, electronic and computational complexity, and is especially suited for use in multiplexed or branched OFS networks for SHM of large and/or distributed structures which need a lot of measurement points.

Performance Assessment of Discontinuous Fibers in Fiber Reinforced Concrete: Current State-of-the-Art

DTIC Science & Technology

2017-07-01

this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY...non-destructively evaluate fiber distributions, orientation, and FRC posttest damage. This technique allows for a closer to meso scale investigation...performance all the while optimizing the material and improving desired performance by designing materials based on individual constituent

Identification and Analyses of AUX-IAA target genes controlling multiple pathways in developing fiber cells of Gossypium hirsutum L

PubMed Central

Nigam, Deepti; Sawant, Samir V

2013-01-01

Technological development led to an increased interest in systems biological approaches in plants to characterize developmental mechanism and candidate genes relevant to specific tissue or cell morphology. AUX-IAA proteins are important plant-specific putative transcription factors. There are several reports on physiological response of this family in Arabidopsis but in cotton fiber the transcriptional network through which AUX-IAA regulated its target genes is still unknown. in-silico modelling of cotton fiber development specific gene expression data (108 microarrays and 22,737 genes) using Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNe) reveals 3690 putative AUX-IAA target genes of which 139 genes were known to be AUX-IAA co-regulated within Arabidopsis. Further AUX-IAA targeted gene regulatory network (GRN) had substantial impact on the transcriptional dynamics of cotton fiber, as showed by, altered TF networks, and Gene Ontology (GO) biological processes and metabolic pathway associated with its target genes. Analysis of the AUX-IAA-correlated gene network reveals multiple functions for AUX-IAA target genes such as unidimensional cell growth, cellular nitrogen compound metabolic process, nucleosome organization, DNA-protein complex and process related to cell wall. These candidate networks/pathways have a variety of profound impacts on such cellular functions as stress response, cell proliferation, and cell differentiation. While these functions are fairly broad, their underlying TF networks may provide a global view of AUX-IAA regulated gene expression and a GRN that guides future studies in understanding role of AUX-IAA box protein and its targets regulating fiber development. PMID:24497725

A Sparse Bayesian Learning Algorithm for White Matter Parameter Estimation from Compressed Multi-shell Diffusion MRI.

PubMed

Pisharady, Pramod Kumar; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2017-09-01

We propose a sparse Bayesian learning algorithm for improved estimation of white matter fiber parameters from compressed (under-sampled q-space) multi-shell diffusion MRI data. The multi-shell data is represented in a dictionary form using a non-monoexponential decay model of diffusion, based on continuous gamma distribution of diffusivities. The fiber volume fractions with predefined orientations, which are the unknown parameters, form the dictionary weights. These unknown parameters are estimated with a linear un-mixing framework, using a sparse Bayesian learning algorithm. A localized learning of hyperparameters at each voxel and for each possible fiber orientations improves the parameter estimation. Our experiments using synthetic data from the ISBI 2012 HARDI reconstruction challenge and in-vivo data from the Human Connectome Project demonstrate the improvements.

Micromechanics thermal stress analysis of composites for space structure applications

NASA Technical Reports Server (NTRS)

Bowles, David E.

1991-01-01

This paper presents results from a finite element micromechanics analysis of thermally induced stresses in composites at cryogenic temperatures typical of spacecraft operating environments. The influence of microstructural geometry, constituent and interphase properties, and laminate orientation were investigated. Stress field results indicated that significant matrix stresses occur in composites exposed to typical spacecraft thermal excursions; these stresses varied with laminate orientation and circumferential position around the fiber. The major difference in the predicted response of unidirectional and multidirectional laminates was the presence of tensile radial stresses, at the fiber/matrix interface, in multidirectional laminates with off-axis ply angles greater than 15 deg. The predicted damage initiation temperatures and modes were in good agreement with experimental data for both low (207 GPa) and high (517 GPa) modulus carbon fiber/epoxy composites.

Fiber sensor network with multipoint sensing using double-pass hybrid LPFG-FBG sensor configuration

NASA Astrophysics Data System (ADS)

Yong, Yun-Thung; Lee, Sheng-Chyan; Rahman, Faidz Abd

2017-03-01

This is a study on double-pass intensity-based hybrid Long Period Fiber Grating (LPFG)and Fiber Bragg Grating (FBG) sensor configuration where a fiber sensor network was constructed with multiple sensing capability. The sensing principle is based on interrogation of intensity changes of the reflected signal from an FBG caused by the LPFG spectral response to the surrounding perturbations. The sensor network developed was tested in monitoring diesel adulteration of up to a distance of 8 km. Kerosene concentration from 0% to 50% was added as adulterant into diesel. The sensitivity of the double-pass hybrid LPFG-FBG sensor over multiple points was>0.21 dB/% (for adulteration range of 0-30%) and >0.45 dB/% from 30% to 50% adulteration. It is found that the sensitivity can drop up to 35% when the fiber length increased from 0 km to 8 km (for the case of adulteration of 0-30%). With the multiple sensing capabilities, normalized FBG's reflected power can be demodulated at the same time for comparison of sensitivity performance across various fiber sensors.

Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

NASA Astrophysics Data System (ADS)

Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

2017-01-01

Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1985-04-03

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1987-01-01

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Mechanisms of Plastic Deformation in Collagen Networks Induced by Cellular Forces.

PubMed

Ban, Ehsan; Franklin, J Matthew; Nam, Sungmin; Smith, Lucas R; Wang, Hailong; Wells, Rebecca G; Chaudhuri, Ovijit; Liphardt, Jan T; Shenoy, Vivek B

2018-01-23

Contractile cells can reorganize fibrous extracellular matrices and form dense tracts of fibers between neighboring cells. These tracts guide the development of tubular tissue structures and provide paths for the invasion of cancer cells. Here, we studied the mechanisms of the mechanical plasticity of collagen tracts formed by contractile premalignant acinar cells and fibroblasts. Using fluorescence microscopy and second harmonic generation, we quantified the collagen densification, fiber alignment, and strains that remain within the tracts after cellular forces are abolished. We explained these observations using a theoretical fiber network model that accounts for the stretch-dependent formation of weak cross-links between nearby fibers. We tested the predictions of our model using shear rheology experiments. Both our model and rheological experiments demonstrated that increasing collagen concentration leads to substantial increases in plasticity. We also considered the effect of permanent elongation of fibers on network plasticity and derived a phase diagram that classifies the dominant mechanisms of plasticity based on the rate and magnitude of deformation and the mechanical properties of individual fibers. Plasticity is caused by the formation of new cross-links if moderate strains are applied at small rates or due to permanent fiber elongation if large strains are applied over short periods. Finally, we developed a coarse-grained model for plastic deformation of collagen networks that can be employed to simulate multicellular interactions in processes such as morphogenesis, cancer invasion, and fibrosis. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Frequency transfer via a two-way optical phase comparison on a multiplexed fiber network.

PubMed

Calosso, C E; Bertacco, E; Calonico, D; Clivati, C; Costanzo, G A; Frittelli, M; Levi, F; Mura, A; Godone, A

2014-03-01

We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise is passively canceled, and we compared two optical frequencies at the ultimate 10(-21) stability level. The experiment was performed on a 47 km fiber that is part of the metropolitan network for Internet traffic. The technique relies on the synchronous measurement of the optical phases at the two ends of the link, which is here performed by digital electronics. This scheme offers some advantages with respect to active noise cancellation schemes, as the light travels only once in the fiber.

CWRUnet--Case History of a Campus-Wide Fiber-to-the-Desktop Network.

ERIC Educational Resources Information Center

Neff, Raymond K.; Haigh, Peter J.

1992-01-01

This article describes the development at Case Western Reserve University of an all-fiber optic communications network linking 7,300 outlets (faculty offices, student residences, classrooms, libraries, and laboratories) with computer data, television, audio, facsimile, and image information services. (Author/DB)

Elasticity and photoelasticity relationships for polyethylene terephthalate fiber networks by molecular simulation

NASA Astrophysics Data System (ADS)

Nayak, Kapileswar; Das, Sushanta; Nanavati, Hemant

2008-01-01

We present a framework for the development of elasticity and photoelasticity relationships for polyethylene terephthalate fiber networks, incorporating aspects of the primary molecular structure. Semicrystalline polymeric fiber networks are modeled as sequentially arranged crystalline and amorphous regions. Rotational isomeric states-Monte Carlo simulations of amorphous chains of up to 360 bonds (degree of polymerization, DP =60), confined between and bridging infinite impenetrable crystalline walls, have been characterized by Ω, the probability density of the intercrystal separation h, and Δβ, the polarizability anisotropy. lnΩ and Δβ have been modeled as functions of h, yielding the chain deformation relationships. The development has been extended to the fiber network to yield the photoelasticity relationships. We execute our framework by fitting to experimental stress-elongation data and employing the single fitted parameter to directly predict the birefringence-elongation behavior, without any further fitting. Incorporating the effect of strain-induced crystallization into the framework makes it physically more meaningful and yields accurate predictions of the birefringence-elongation behavior.

Prediction of thermal conductivity of polyvinylpyrrolidone (PVP) electrospun nanocomposite fibers using artificial neural network and prey-predator algorithm.

PubMed

Khan, Waseem S; Hamadneh, Nawaf N; Khan, Waqar A

2017-01-01

In this study, multilayer perception neural network (MLPNN) was employed to predict thermal conductivity of PVP electrospun nanocomposite fibers with multiwalled carbon nanotubes (MWCNTs) and Nickel Zinc ferrites [(Ni0.6Zn0.4) Fe2O4]. This is the second attempt on the application of MLPNN with prey predator algorithm for the prediction of thermal conductivity of PVP electrospun nanocomposite fibers. The prey predator algorithm was used to train the neural networks to find the best models. The best models have the minimal of sum squared error between the experimental testing data and the corresponding models results. The minimal error was found to be 0.0028 for MWCNTs model and 0.00199 for Ni-Zn ferrites model. The predicted artificial neural networks (ANNs) responses were analyzed statistically using z-test, correlation coefficient, and the error functions for both inclusions. The predicted ANN responses for PVP electrospun nanocomposite fibers were compared with the experimental data and were found in good agreement.

Unravelling the secret of seed-based gels in water: the nanoscale 3D network formation.

PubMed

Samateh, Malick; Pottackal, Neethu; Manafirasi, Setareh; Vidyasagar, Adiyala; Maldarelli, Charles; John, George

2018-05-09

Chia (Salvia hispanica) and basil (Ocimum basilicum) seeds have the intrinsic ability to form a hydrogel concomitant with moisture-retention, slow releasing capability and proposed health benefits such as curbing diabetes and obesity by delaying digestion process. However, the underlying mode of gelation at nanoscopic level is not clearly explained or explored. The present study elucidates and corroborates the hypothesis that the gelling behavior of such seeds is due to their nanoscale 3D-network formation. The preliminary study revealed the influence of several conditions like polarity, pH and hydrophilicity/hydrophobicity on fiber extrusion from the seeds which leads to gelation. Optical microscopic analysis clearly demonstrated bundles of fibers emanating from the seed coat while in contact with water, and live growth of fibers to form 3D network. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies confirmed 3D network formation with fiber diameters ranging from 20 to 50 nm.

Highly Absorbent Antibacterial Hemostatic Dressing for Healing Severe Hemorrhagic Wounds

PubMed Central

Li, Ting-Ting; Lou, Ching-Wen; Chen, An-Pang; Lee, Mong-Chuan; Ho, Tsing-Fen; Chen, Yueh-Sheng; Lin, Jia-Horng

2016-01-01

To accelerate healing of severe hemorrhagic wounds, a novel highly absorbent hemostatic dressing composed of a Tencel®/absorbent-cotton/polylactic acid nonwoven base and chitosan/nanosilver antibacterial agent was fabricated by using a nonwoven processing technique and a freeze-drying technique. This study is the first to investigate the wicking and water-absorbing properties of a nonwoven base by measuring the vertical wicking height and water absorption ratio. Moreover, blood agglutination and hemostatic second tests were conducted to evaluate the hemostatic performance of the resultant wound dressing. The blending ratio of fibers, areal weight, punching density, and fiber orientation, all significantly influenced the vertical moisture wicking property. However, only the first two parameters markedly affected the water absorption ratio. After the nonwoven base absorbed blood, scanning electron microscope (SEM) observation showed that erythrocytes were trapped between the fibrin/clot network and nonwoven fibers when coagulation pathways were activated. Prothrombin time (PT) and activated partial thromboplastin time (APTT) blood agglutination of the resultant dressing decreased to 14.34 and 50.94 s, respectively. In the femoral artery of the rate bleeding model, hemostatic time was saved by 87.2% compared with that of cotton cloth. Therefore, the resultant antibacterial wound dressing demonstrated greater water and blood absorption, as well as hemostatic performance, than the commercially available cotton cloth, especially for healing severe hemorrhagic wounds. PMID:28773912

Fabrication of fiber supported ionic liquids and methods of use

DOEpatents

Luebke, David R; Wickramanayake, Shan

2013-02-26

One or more embodiments relates to the production of a fabricated fiber having an asymmetric polymer network and having an immobilized liquid such as an ionic liquid within the pores of the polymer network. The process produces the fabricated fiber in a dry-wet spinning process using a homogenous dope solution, providing significant advantage over current fabrication methods for liquid-supporting polymers. The fabricated fibers may be effectively utilized for the separation of a chemical species from a mixture based on the selection of the polymer, the liquid, and the solvent utilized in the dope.

New amplifying laser concept for inertial fusion driver

NASA Astrophysics Data System (ADS)

Mourou, G. A.; Labaune, C.; Hulin, D.; Galvanauskas, A.

2008-05-01

This paper presents a new amplifying laser concept designed to produce high energy in either short or long pulses using coherent or incoherent addition of few millions fibers. These are called respectively CAN for Coherent Amplification Network and FAN for Fiber Amplification Network. The fibers would be large core or Large Mode Area (LMA) which have demonstrated up to 10, mJ output energy per fiber1. Such a system could meet the driver criteria of Inertial Fusion Energy (IFE) power plants based on Inertial Confinement Fusion (ICF), in particular high efficiency and high repetition rate.

Fiber networks amplify active stress

NASA Astrophysics Data System (ADS)

Lenz, Martin; Ronceray, Pierre; Broedersz, Chase

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. While fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. I will present a comprehensive theoretical study of force transmission in these networks. I will show that the linear, small-force response of the networks is remarkably simple, as the macroscopic active stress depends only on the geometry of the force-exerting unit. In contrast, as non-linear buckling occurs around these units, local active forces are rectified towards isotropic contraction and strongly amplified. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. I will show that our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks, and that they shed light on the role of the network microstructure in shaping active stresses in cells and tissue.

Evaluation of the effect of synthetic fibers and nonwoven geotextile reinforcement on the stability of heavy clay embankments.

DOT National Transportation Integrated Search

2003-04-01

This study evaluates two methods for repairing slope surface failures of clayey soil embankments. One method involves reinforcing the cohesive soils with randomly oriented synthetic fibers; the other method incorporates non-woven geotextiles. The per...

Structural investigation of porcine stomach mucin by X-ray fiber diffraction and homology modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veluraja, K., E-mail: veluraja@msuniv.ac.in; Vennila, K.N.; Umamakeshvari, K.

Research highlights: {yields} Techniques to get oriented mucin fibre. {yields} X-ray fibre diffraction pattern for mucin. {yields} Molecular modeling of mucin based on X-ray fibre diffraction pattern. -- Abstract: The basic understanding of the three dimensional structure of mucin is essential to understand its physiological function. Technology has been developed to achieve orientated porcine stomach mucin molecules. X-ray fiber diffraction of partially orientated porcine stomach mucin molecules show d-spacing signals at 2.99, 4.06, 4.22, 4.7, 5.37 and 6.5 A. The high intense d-spacing signal at 4.22 A is attributed to the antiparallel {beta}-sheet structure identified in the fraction of themore » homology modeled mucin molecule (amino acid residues 800-980) using Nidogen-Laminin complex structure as a template. The X-ray fiber diffraction signal at 6.5 A reveals partial organization of oligosaccharides in porcine stomach mucin. This partial structure of mucin will be helpful in establishing a three dimensional structure for the whole mucin molecule.« less

Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links.

PubMed

Pinkert, T J; Böll, O; Willmann, L; Jansen, G S M; Dijck, E A; Groeneveld, B G H M; Smets, R; Bosveld, F C; Ubachs, W; Jungmann, K; Eikema, K S E; Koelemeij, J C J

2015-02-01

Results of optical frequency transfer over a carrier-grade dense-wavelength-division-multiplexing (DWDM) optical fiber network are presented. The relation between soil temperature changes on a buried optical fiber and frequency changes of an optical carrier through the fiber is modeled. Soil temperatures, measured at various depths by the Royal Netherlands Meteorology Institute (KNMI) are compared with observed frequency variations through this model. A comparison of a nine-day record of optical frequency measurements through the 2×298  km fiber link with soil temperature data shows qualitative agreement. A soil temperature model is used to predict the link stability over longer periods (days-months-years). We show that optical frequency dissemination is sufficiently stable to distribute and compare, e.g., rubidium frequency standards over standard DWDM optical fiber networks using unidirectional fibers.

Structure-induced variation of thermal conductivity in epoxy resin fibers.

PubMed

Zeng, Xiaoliang; Xiong, Yucheng; Fu, Qiang; Sun, Rong; Xu, Jianbin; Xu, Dongyan; Wong, Ching-Ping

2017-08-03

The ability to control thermal conductivity is important in a wide variety of applications, especially in heat removal, heat insulation, and thermoelectric energy conversion. Herein, we reveal that the thermal conductivity of epoxy resin fibers increases on decreasing the fiber diameter and surpasses the bulk value (0.25 W m -1 K -1 at 300 K) for the fiber with a diameter of 211 nm. The variation of thermal conductivity in epoxy resin fibers can likely be attributed to their microstructure change-enhanced interface phonon scattering between amorphous and crystalline regions and the enhanced alignment of the molecular chain orientation.

Distributed Sensing of Carbon-Epoxy Composites and Filament Wound Pressure Vessels Using Fiber-Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, J.; Kaul, R.; Taylor, S.; Myer, G.; Jackson, K.; Osei, A.; Sharma, A.

2003-01-01

Multiple Fiber Bragg-gratings are embedded in carbon-epoxy laminates as well as in composite wound pressure vessel. Structural properties of such composites are investigated. The measurements include stress-strain relation in laminates and Poisson's ratio in several specimens with varying orientation of the optical fiber Bragg-sensor with respect to the carbon fiber in an epoxy matrix. Additionally, fiber Bragg gratings are bonded on the surface of these laminates and cylinders fabricated out of carbon-epoxy composites and multiple points are monitored and compared for strain measurements at several locations.

On the Presence of Affine Fibril and Fiber Kinematics in the Mitral Valve Anterior Leaflet

PubMed Central

Lee, Chung-Hao; Zhang, Will; Liao, Jun; Carruthers, Christopher A.; Sacks, Jacob I.; Sacks, Michael S.

2015-01-01

In this study, we evaluated the hypothesis that the constituent fibers follow an affine deformation kinematic model for planar collagenous tissues. Results from two experimental datasets were utilized, taken at two scales (nanometer and micrometer), using mitral valve anterior leaflet (MVAL) tissues as the representative tissue. We simulated MVAL collagen fiber network as an ensemble of undulated fibers under a generalized two-dimensional deformation state, by representing the collagen fibrils based on a planar sinusoidally shaped geometric model. The proposed approach accounted for collagen fibril amplitude, crimp period, and rotation with applied macroscopic tissue-level deformation. When compared to the small angle x-ray scattering measurements, the model fit the data well, with an r2 = 0.976. This important finding suggests that, at the homogenized tissue-level scale of ∼1 mm, the collagen fiber network in the MVAL deforms according to an affine kinematics model. Moreover, with respect to understanding its function, affine kinematics suggests that the constituent fibers are largely noninteracting and deform in accordance with the bulk tissue. It also suggests that the collagen fibrils are tightly bounded and deform as a single fiber-level unit. This greatly simplifies the modeling efforts at the tissue and organ levels, because affine kinematics allows a straightforward connection between the macroscopic and local fiber strains. It also suggests that the collagen and elastin fiber networks act independently of each other, with the collagen and elastin forming long fiber networks that allow for free rotations. Such freedom of rotation can greatly facilitate the observed high degree of mechanical anisotropy in the MVAL and other heart valves, which is essential to heart valve function. These apparently novel findings support modeling efforts directed toward improving our fundamental understanding of tissue biomechanics in healthy and diseased conditions. PMID:25902446