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Sample records for plane load-bearing structures

  1. Ceramic Fiber Structures for Cryogenic Load-Bearing Applications

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.; Eckel, Andrew J.

    2009-01-01

    This invention is intended for use as a load-bearing device under cryogenic temperatures and/or abrasive conditions (i.e., during missions to the Moon). The innovation consists of small-diameter, ceramic fibers that are woven or braided into devices like ropes, belts, tracks, or cables. The fibers can be formed from a variety of ceramic materials like silicon carbide, carbon, aluminosilicate, or aluminum oxide. The fiber architecture of the weave or braid is determined by both the fiber properties and the mechanical requirements of the application. A variety of weave or braid architectures is possible for this application. Thickness of load-bearing devices can be achieved by using either a 3D woven structure, or a layered, 2D structure. For the prototype device, a belt approximately 0.10 in. (0.25 cm) thick, and 3.0 in. (7.6 cm) wide was formed by layering and stitching a 2D aluminosilicate fiber weave.

  2. Properties of structural clay load-bearing wall tile

    SciTech Connect

    Flanagan, R.D.; Butala, M.B.; Bennett, R.M.

    1993-02-02

    Structural clay tile has been produced in the United States and used in load-bearing walls for over a century. While the fundamentals of the manufacturing process have not changed significantly, specific fabrication details and material additives have led to increased strength and economy of current products. Red burned clay masonry units were sampled and tested in accordance with applicable ASTM standards. Objective of the tests was to compare tiles used in the original construction of the Oak Ridge Y-12 Plant (1940s) to tiles being used in current large scale laboratory tests and wall repairs. Results of the tests are compared to other contemporary and historic clay tile data. The effects of the evolution of clay tile manufacturing on engineering properties is also examined.

  3. Composite load bearing outer skin for an arctic structure and a method for erecting same

    SciTech Connect

    Chen, J.; Birdy, J. N.; Watt, B. J.

    1985-08-27

    The load bearing outer skin contains an inner assembly and an outer assembly. Both the inner and outer assemblies include a skin plate member which is stiffened by stiffeners welded to one side of the skin plate member. The stiffeners are located at spaced intervals from each other and are disposed substantially perpendicular to the skin plate member. The inner and outer assembly are placed substantially parallel to each other to form a composite structure having an internal cavity defined by the inner and outer plates. The stiffeners of the inner assembly and the outer assembly are disposed in the cavity at a spaced relation to each other and extend partly into the cavity. A cementitious material substantially fills the cavity thereby completing the load bearing outer skin structure. The stiffeners may be flat steel plates or may have the profile of structural shapes such as angles or T's among others.

  4. Conformal load-bearing antenna structures (CLAS): initiative for multiple military and commercial applications

    NASA Astrophysics Data System (ADS)

    Lockyer, Allen J.; Alt, Kevin H.; Kudva, Jayanth N.; Kinslow, Robert W.; Goetz, Allan C.

    1997-06-01

    The Structures Division of the Air Force's Wright Laboratory is sponsoring the development and demonstration of a new high pay-off technology termed CLAS--Conformal Load Bearing Antenna Structures. Northrop Grumman Corporation and TRW/ASD are developing the technology under the `Smart-Skin Structure Technology Demonstration (S3D)' program, contract, No. F33615-93-C-3200. The program goal is to design, develop, fabricate, and test a CLAS component and lay the foundation for future work where potential benefits from structurally integrated antennas may be realized. Key issues will focus but are not limited to the design, structures, and manufacturing aspects of antenna embedment into load bearing aircraft structures. Results from Phase 1 of the program have been previously reported, where initial pay-offs in reducing overall airframe acquisition and support cost, weight, signature, and drag were quantitatively and qualitatively identified. A full-sized CLAS component, featuring a broadband multi-arm spiral embedded in sandwich stiffened structure, will be fabricated and tested for static strength, durability, and damage tolerance. Basic electrical performance, (e.g., radiation patterns, gain, and impedance) will also be verified; however, extensive electrical validation will be the subject of further work. Key aspects of the work and progress to date are detailed below. Also covered are future projections of CLAS technology expansion beyond tactical aircraft into other military products highlighting ships, army vehicles, and `spin-off' commercial applications to civil aircraft and the automotive industry.

  5. Influence of structural load-bearing scaffolds on mechanical load- and BMP-2-mediated bone regeneration.

    PubMed

    McDermott, Anna M; Mason, Devon E; Lin, Angela S P; Guldberg, Robert E; Boerckel, Joel D

    2016-09-01

    A common design constraint in functional tissue engineering is that scaffolds intended for use in load-bearing sites possess similar mechanical properties to the replaced tissue. Here, we tested the hypothesis that in vivo loading would enhance bone morphogenetic protein-2 (BMP-2)-mediated bone regeneration in the presence of a load-bearing PLDL scaffold, whose pores and central core were filled with BMP-2-releasing alginate hydrogel. First, we evaluated the effects of in vivo mechanical loading on bone regeneration in the structural scaffolds. Second, we compared scaffold-mediated bone regeneration, independent of mechanical loading, with alginate hydrogel constructs, without the structural scaffold, that have been shown previously to facilitate in vivo mechanical stimulation of bone formation. Contrary to our hypothesis, mechanical loading had no effect on bone formation, distribution, or biomechanical properties in structural scaffolds. Independent of loading, the structural scaffolds reduced bone formation compared to non-structural alginate, particularly in regions in which the scaffold was concentrated, resulting in impaired functional regeneration. This is attributable to a combination of stress shielding by the scaffold and inhibition of cellular infiltration and tissue ingrowth. Collectively, these data question the necessity of scaffold similarity to mature tissue at the time of implantation and emphasize development of an environment conducive to cellular activation of matrix production and ultimate functional regeneration.

  6. Network structure of the mussel plaque and its significance for load bearing and adhesion

    NASA Astrophysics Data System (ADS)

    Filippidi, Emmanouela; Kim, Juntae; Waite, J. Herbert; Helgeson, Matthew; Valentine, Megan T.

    2015-03-01

    Marine mussels attach to rocks, each other, and a variety of surfaces via a flat, wide plaque that is interpenetrated by the collagen fibers of a thin, long thread that connects the plaque to the mussel body. The unusually strong adhesion of the plaque has long been attributed to the molecular design of its adhesive proteins that can form a variety of strong chemical bonds. However, the molecular energies for de-adhesion are orders of magnitude smaller than the macroscopic energies measured. We propose that the mesoscopic design of the plaque is critical in enhancing load bearing and eventually adhesion. We present new results on the structure of the plaque studied via electron microscopy and neutron scattering that exhibit a plaque geometry reminiscent of structural foams. Our studies reveal a collection of pores with an inner network, further connected with an outer network. The final structure can be described by two length scales. A synthetic soft system is constructed in an effort to mimic the two-lengthscale structure of the natural plaques. The structure of the native and synthetic systems is compared with the ultimate goal of evaluating the importance of the mesoscopic structure to mechanics and adhesion. NSF MRSEC IRG-I.

  7. Active load path adaption in a simple kinematic load-bearing structure due to stiffness change in the structure's supports

    NASA Astrophysics Data System (ADS)

    Gehb, C. M.; Platz, R.; Melz, T.

    2016-09-01

    Load-bearing structures with kinematic functions enable and disable degrees of freedom and are part of many mechanical engineering applications. The relative movement between a wheel and the body of a car or a landing gear and an aircraft fuselage are examples for load-bearing systems with defined kinematics. In most cases, the load is transmitted through a predetermined load path to the structural support interfaces. However, unexpected load peaks or varying health condition of the system's supports, which means for example varying damping and stiffness characteristics, may require an active adjustment of the load path. However, load paths transmitted through damaged or weakened supports can be the reason for reduced comfort or even failure. In this paper a simplified 2D two mass oscillator with two supports is used to numerically investigate the potential of controlled adaptive auxiliary kinematic guidance elements in a load-bearing structure to adapt the load path depending on the stiffness change, representing damage of the supports. The aim is to provide additional forces in the auxiliary kinematic guidance elements for two reasons. On the one hand, one of the two supports that may become weaker through stiffness change will be relieved from higher loading. On the other hand, tilting due to different compliance in the supports will be minimized. Therefore, shifting load between the supports during operation could be an effective option.

  8. A two-dimensional theory of coupled electro-magneto-mechanical plates as an application to load-bearing antenna structures

    NASA Astrophysics Data System (ADS)

    Santapuri, S.; Bechtel, S. E.

    2011-04-01

    Multifunctional materials and structures possess the ability to perform multiple tasks by combining structural integrity with sensing and actuating capabilities. Recent progress in the development of such materials/structures has made concepts like load-bearing antennas or load-bearing batteries feasible and formed new research possibilities. Load-bearing antenna structures are multifunctional sensing and actuating devices integrated with a load-bearing structure, i.e. they can simultaneously function as a mechanical structure and an electromagnetic antenna. Such an antenna structure is subjected to mechanical forces, temperature gradients, and electromagnetic fields, giving rise to highly-coupled nonlinear thermo-electro-magneto-mechanical (TEMM) behavior. The current research focuses on modeling and characterizing the nonlinear 3-D coupled behavior of TEMM materials, consistent with first principles. This theoretical framework is specifically aimed at modeling and analysis of load-bearing antenna structures. In this paper we demonstrate the development of analytical techniques and computational tools for multiscale, multi-physics modeling of load-bearing antenna structures. The mathematical model, based predominantly on first principles, employs the thermomechanical governing equations coupled with Maxwell's equations. Our modeling has identified 92 nondimensional numbers which quantify the competition between physical effects in the operation of load-bearing antenna. A fixed relative ordering of all competing effects determines a regime of antenna/environment interaction. In this work, we demonstrate a comprehensive framework to derive the 3-D governing equations for a given regime. For thin geometries, these equations are further reduced to 2-D model, using series expansion and perturbation techniques. Mathematical modeling of thin electro-magneto-mechanical plates can have applications like design and optimization of load-bearing antennas structures. This

  9. Compliant load-bearing skins and structures for morphing aircraft applications

    NASA Astrophysics Data System (ADS)

    Olympio, Kingnide Raymond

    Aircraft morphing has the potential to significantly improve the performance of an aircraft over its flight envelope and expand its ight capability to allow it to perform dramatically different missions. The multiple projects carried on in the past three decades have considerably helped improve the designing of actuation systems and the utilization of smart materials for morphing aircraft structures. However, morphing aircraft and especially aircraft undergoing large shape change still face some significant technical issues. Among them, the skin covering the morphing structure must meet challenging requirements that no current conventional material fully satisfy. The design of such skin, which should be able to undergo large deformations and to carry air-loads, has received some attention in the last several years but no satisfactory solution has been found yet. In the current study, the design of compliant cellular structures and flexible skins for morphing aircraft structures is investigated for two different morphing deformations. The first morphing deformation considered corresponds to one-dimensional morphing which is representative of a wing or blade changing its chord or span. The second morphing deformation considered is shear-compression morphing which can be found in some morphing wing undergoing change in area, sweep and chord such as NextGen Aeronautics' morphing wing. Topologies of compliant cellular structures which can be used for these two types of structures are first calculated using a multi-objective approach. These topologies are calculated based on linear kinematics but the effect of geometric nonlinearities is also investigated. Then, ways to provide a smooth surface were investigated by considering a general honeycomb substructure with infill, bonded face-sheet or scales. This allowed justifying an overall skin concept made of a cellular substructure with a bonded face-sheet. Lastly, the design of an improved skin for NextGen Aeronautics

  10. Spider silk as a load bearing biomaterial: tailoring mechanical properties via structural modifications

    NASA Astrophysics Data System (ADS)

    Brown, Cameron P.; Rosei, Federico; Traversa, Enrico; Licoccia, Silvia

    2011-03-01

    Spider silk shows great potential as a biomaterial: in addition to biocompatibility and biodegradability, its strength and toughness are greater than native biological fibres (e.g. collagen), with toughness exceeding that of synthetic fibres (e.g. nylon). Although the ultimate tensile strength and toughness at failure are unlikely to be limiting factors, its yield strain of 2% is insufficient, particularly for biomedical application because of the inability to mimic the complex ultrastructure of natural tissues with current tissue engineering approaches. To harness the full potential of spider silk as a biomaterial, it is therefore necessary to increase its yield strain. In this paper, we discuss the means by which the mechanical properties of spider silk, particularly the yield strain, can be optimized through structural modifications.

  11. Spider silk as a load bearing biomaterial: tailoring mechanical properties via structural modifications.

    PubMed

    Brown, Cameron P; Rosei, Federico; Traversa, Enrico; Licoccia, Silvia

    2011-03-01

    Spider silk shows great potential as a biomaterial: in addition to biocompatibility and biodegradability, its strength and toughness are greater than native biological fibres (e.g. collagen), with toughness exceeding that of synthetic fibres (e.g. nylon). Although the ultimate tensile strength and toughness at failure are unlikely to be limiting factors, its yield strain of 2% is insufficient, particularly for biomedical application because of the inability to mimic the complex ultrastructure of natural tissues with current tissue engineering approaches. To harness the full potential of spider silk as a biomaterial, it is therefore necessary to increase its yield strain. In this paper, we discuss the means by which the mechanical properties of spider silk, particularly the yield strain, can be optimized through structural modifications. PMID:21212901

  12. Effects of load-bearing exercise on skeletal structure and mechanics differ between outbred populations of mice.

    PubMed

    Wallace, Ian J; Judex, Stefan; Demes, Brigitte

    2015-03-01

    Effects of load-bearing exercise on skeletal structure and mechanical properties can vary between inbred strains of mice. Here, we examine whether such variation also exists at the population level. An experiment was performed with two outbred mouse stocks that have been reproductively isolated for >120 generations (Hsd:ICR, Crl:CD1). Growing females from each stock were either treated with a treadmill-running regimen for 1 month or served as controls. Limb forces were recorded with a force plate and cage activity monitored to verify that they were similar between stocks. After the experiment, femoral cortical and trabecular bone structure were quantified with micro-CT in the mid-diaphysis and distal metaphysis, respectively, and diaphyseal structural strength was determined with mechanical testing. Among Hsd:ICR mice, running led to significant improvements in diaphyseal bone quantity, structural geometry, and mechanical properties, as well as enhanced trabecular morphology. In contrast, among Crl:CD1 mice, the same running regimen had little effect on cortical and trabecular structure and significantly reduced diaphyseal resistance to fracture. In neither stock was body mass, muscle mass, or cage activity level different between runners and controls. Given that most environmental variables were controlled in this study, the differential effects of exercise on Hsd:ICR and Crl:CD1 bones were likely due to genetic differences between stocks. These results suggest that the benefits of loading for bone may vary between human populations (e.g., ethnic groups), in which case exercise programs and technologies designed to promote bone health with mechanical signals may be more advantageous to certain populations than others. PMID:25460574

  13. Load Bearing Innovative Construction from Glass

    NASA Astrophysics Data System (ADS)

    Kalamar, R.; Eliášová, M.

    2015-11-01

    Glass plays an exceptional role in the modern architecture due to the optical properties and transparency. Structural elements from glass like beams, facades and roofs are relatively frequent in common practice [1]. Although glass has significantly higher compressive strength in comparison with tensile strength, load bearing glass elements are relatively rare. This opens up new opportunities for application of glass in such structures as transparent columns loaded by the axial force. This paper summarizes the experimental results of the tests on glass columns loaded by centric pressure, which were performed in the laboratories of the CTU in Prague, Faculty of Civil Engineering. The first set of experiments was composed of three specimens in a reduced scale 1:2 to verify real behaviour of the specimens with enclosed hollow cross-section. The main goal of the experiment was to determine force at the first breakage and consequently the maximal force at the collapse of this element.

  14. Nanogel Aerogel as Load Bearing Insulation for Cryogenic Systems

    NASA Astrophysics Data System (ADS)

    Koravos, J. J.; Miller, T. M.; Fesmire, J. E.; Coffman, B. E.

    2010-04-01

    Load support structures in cryogenic storage, transport and processing systems are large contributors to the total heat leak of the system. Conventional insulation systems require the use of these support members in order to stabilize the process fluid enclosure and prevent degradation of insulation performance due to compression. Removal of these support structures would substantially improve system efficiency. Nanogel aerogel insulation performance is tested at vacuum pressures ranging from high vacuum to atmospheric pressure and under loads from loosely packed to greater than 10,000 Pa. Insulation performance is determined using boil-off calorimetry with liquid nitrogen as the latent heat recipient. Two properties of the aerogel insulation material suit it to act as a load bearing "structure" in a process vessel: (1) Ability to maintain thermal performance under load; (2) Elasticity when subjected to load. Results of testing provide positive preliminary indication that these properties allow Nanogel aerogel to effectively be used as a load bearing insulation in cryogenic systems.

  15. On optimal hierarchy of load-bearing biological materials

    PubMed Central

    Zhang, Zuoqi; Zhang, Yong-Wei; Gao, Huajian

    2011-01-01

    Load-bearing biological materials such as shell, mineralized tendon and bone exhibit two to seven levels of structural hierarchy based on constituent materials (biominerals and proteins) of relatively poor mechanical properties. A key question that remains unanswered is what determines the number of hierarchical levels in these materials. Here we develop a quasi-self-similar hierarchical model to show that, depending on the mineral content, there exists an optimal level of structural hierarchy for maximal toughness of biocomposites. The predicted optimal levels of hierarchy and cooperative deformation across multiple structural levels are in excellent agreement with experimental observations. PMID:20810437

  16. Designing functionally graded materials with superior load-bearing properties.

    PubMed

    Zhang, Yu; Sun, Ming-Jie; Zhang, Denzil

    2012-03-01

    Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidelines for designing FGMs with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (E(b)/E(s)) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15load-bearing capacity, 20-50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications.

  17. The nebulin SH3 domain is dispensable for normal skeletal muscle structure but is required for effective active load bearing in mouse.

    PubMed

    Yamamoto, Daniel L; Vitiello, Carmen; Zhang, Jianlin; Gokhin, David S; Castaldi, Alessandra; Coulis, Gerald; Piaser, Fabio; Filomena, Maria Carmela; Eggenhuizen, Peter J; Kunderfranco, Paolo; Camerini, Serena; Takano, Kazunori; Endo, Takeshi; Crescenzi, Marco; Luther, Pradeep K L; Lieber, Richard L; Chen, Ju; Bang, Marie-Louise

    2013-12-01

    Nemaline myopathy (NM) is a congenital myopathy with an estimated incidence of 150,000 live births. It is caused by mutations in thin filament components, including nebulin, which accounts for about 50% of the cases. The identification of NM cases with nonsense mutations resulting in loss of the extreme C-terminal SH3 domain of nebulin suggests an important role of the nebulin SH3 domain, which is further supported by the recent demonstration of its role in IGF-1-induced sarcomeric actin filament formation through targeting of N-WASP to the Z-line. To provide further insights into the functional significance of the nebulin SH3 domain in the Z-disk and to understand the mechanisms by which truncations of nebulin lead to NM, we took two approaches: (1) an affinity-based proteomic screening to identify novel interaction partners of the nebulin SH3 domain; and (2) generation and characterization of a novel knockin mouse model with a premature stop codon in the nebulin gene, eliminating its C-terminal SH3 domain (NebΔSH3 mouse). Surprisingly, detailed analyses of NebΔSH3 mice revealed no structural or histological skeletal muscle abnormalities and no changes in gene expression or localization of interaction partners of the nebulin SH3 domain, including myopalladin, palladin, zyxin and N-WASP. Also, no significant effect on peak isometric stress production, passive tensile stress or Young's modulus was found. However, NebΔSH3 muscle displayed a slightly altered force-frequency relationship and was significantly more susceptible to eccentric contraction-induced injury, suggesting that the nebulin SH3 domain protects against eccentric contraction-induced injury and possibly plays a role in fine-tuning the excitation-contraction coupling mechanism. PMID:24046450

  18. Method of recertifying a loaded bearing member

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G. (Inventor)

    1992-01-01

    A method is described of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasonic tone burst generated by a first pulsed phased locked loop (P2L2) equipment configuration. Once a lock point number S is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using a second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor F02=((F1-F3)/F1) 1000000. Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship (-1000000)CI(((F2-F4)/F2)-Fo2), wherein CI is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.

  19. Morphogenic Peptides in Regeneration of Load Bearing Tissues.

    PubMed

    Moeinzadeh, Seyedsina; Jabbari, Esmaiel

    2015-01-01

    Morphogenic proteins due to their short half-life require high doses of growth factors in regeneration of load bearing tissues which leads to undesirable side effects. These side effects include bone overgrowth, tumor formation and immune reaction. An alternative approach to reduce undesirable side effects of proteins in regenerative medicine is to use morphogenic peptides derived from the active domains of morphogenic proteins or soluble and insoluble components of the extracellular matrix of mineralized load bearing tissues to induce differentiation of progenitor cells, mineralization, maturation and bone formation. In that regard, many peptides with osteogenic activity have been discovered. These include peptides derived from bone morphogenic proteins (BMPs), those based on interaction with integrin and heparin-binding receptors, collagen derived peptides, peptides derived from other soluble ECM proteins such as bone sialoprotein and enamel matrix proteins, and those peptides derived from vasculoinductive and neuro-inductive proteins. Although these peptides show significant osteogenic activity in vitro and increase mineralization and bone formation in animal models, they are not widely used in clinical orthopedic applications as an alternative to morphogenic proteins. This is partly due to the limited availability of data on structure and function of morphogenic peptides in physiological medium, particularly in tissue engineered scaffolds. Due to their amphiphilic nature, peptides spontaneously self-assemble and aggregate into micellar structures in physiological medium. Aggregation alters the sequence of amino acids in morphogenic peptides that interact with cell surface receptors thus affecting osteogenic activity of the peptide. Aggregation and micelle formation can dramatically reduce the active concentration of morphogenic peptides with many-fold increase in peptide concentration in physiological medium. Other factors that affect bioactivity are the non

  20. Load-bearing increase in alumina evoked by introduction of a functional glass gradient

    PubMed Central

    Dorthé, Erik; Zhang, Yu

    2011-01-01

    Alumina is the most commonly used ceramic in orthopedics due mainly to its wear resistance and chemical inertness. However, alumina has relatively low load-bearing capacity compared to other advanced ceramics, such as zirconia. We hypothesized that grading the elastic modulus at the surfaces may substantially increase the load-bearing capacity of alumina. In this study, graded structures were fabricated by infiltrating glass into dense alumina plates, resulting in a diminished modulus at the surface layers. The plates were then bonded to polycarbonate substrates and subjected to flexural loading with various loading rates spanning five orders of magnitude (dynamic fatigue) in water. Infiltrated specimens showed an increase in flexural load over homogenous controls for all loading rates, despite the graded alumina exhibiting greater load rate dependence than their homogenous counterparts. Our results indicate that controlled elastic gradients at the surface could be highly beneficial in improving the load-bearing capacity of alumina ceramics. PMID:22639492

  1. Load-Bearing Capacity of Fiber-Reinforced Composite Abutments and One-Piece Implants.

    PubMed

    Etxeberria, Marina; Abdulmajeed, Aous A; Escuin, Tomas; Vinas, Miguel; Lassila, Lippo V J; Närhi, Timo O

    2015-06-01

    Fiber-reinforced composites (FRC) can potentially help in a physiologic stress transmission due to its excellent biomechanical matching with living tissues. Novel one-piece FRC implants and abutments with two different fiber orientations were loaded until failure to assess the load-bearing capacity, fracture patterns, and precision of fit. The one-piece FRC implants showed significantly higher load-bearing capacity compared to FRC abutments regardless of the fiber orientation (p < 0.001). For FRC abutments, bidirectional abutments showed significantly higher loads compared to unidirectional abutments (p < 0.001). The type of structure and fiber orientation are strong determinant factors of the load-bearing capacity of FRC implants and abutments. PMID:26373199

  2. Fracture behaviors of ceramic tissue scaffolds for load bearing applications

    PubMed Central

    Entezari, Ali; Roohani-Esfahani, Seyed-Iman; Zhang, Zhongpu; Zreiqat, Hala; Dunstan, Colin R.; Li, Qing

    2016-01-01

    Healing large bone defects, especially in weight-bearing locations, remains a challenge using available synthetic ceramic scaffolds. Manufactured as a scaffold using 3D printing technology, Sr-HT-Gahnite at high porosity (66%) had demonstrated significantly improved compressive strength (53 ± 9 MPa) and toughness. Nevertheless, the main concern of ceramic scaffolds in general remains to be their inherent brittleness and low fracture strength in load bearing applications. Therefore, it is crucial to establish a robust numerical framework for predicting fracture strengths of such scaffolds. Since crack initiation and propagation plays a critical role on the fracture strength of ceramic structures, we employed extended finite element method (XFEM) to predict fracture behaviors of Sr-HT-Gahnite scaffolds. The correlation between experimental and numerical results proved the superiority of XFEM for quantifying fracture strength of scaffolds over conventional FEM. In addition to computer aided design (CAD) based modeling analyses, XFEM was conducted on micro-computed tomography (μCT) based models for fabricated scaffolds, which took into account the geometric variations induced by the fabrication process. Fracture strengths and crack paths predicted by the μCT-based XFEM analyses correlated well with relevant experimental results. The study provided an effective means for the prediction of fracture strength of porous ceramic structures, thereby facilitating design optimization of scaffolds. PMID:27403936

  3. Fracture behaviors of ceramic tissue scaffolds for load bearing applications

    NASA Astrophysics Data System (ADS)

    Entezari, Ali; Roohani-Esfahani, Seyed-Iman; Zhang, Zhongpu; Zreiqat, Hala; Dunstan, Colin R.; Li, Qing

    2016-07-01

    Healing large bone defects, especially in weight-bearing locations, remains a challenge using available synthetic ceramic scaffolds. Manufactured as a scaffold using 3D printing technology, Sr-HT-Gahnite at high porosity (66%) had demonstrated significantly improved compressive strength (53 ± 9 MPa) and toughness. Nevertheless, the main concern of ceramic scaffolds in general remains to be their inherent brittleness and low fracture strength in load bearing applications. Therefore, it is crucial to establish a robust numerical framework for predicting fracture strengths of such scaffolds. Since crack initiation and propagation plays a critical role on the fracture strength of ceramic structures, we employed extended finite element method (XFEM) to predict fracture behaviors of Sr-HT-Gahnite scaffolds. The correlation between experimental and numerical results proved the superiority of XFEM for quantifying fracture strength of scaffolds over conventional FEM. In addition to computer aided design (CAD) based modeling analyses, XFEM was conducted on micro-computed tomography (μCT) based models for fabricated scaffolds, which took into account the geometric variations induced by the fabrication process. Fracture strengths and crack paths predicted by the μCT-based XFEM analyses correlated well with relevant experimental results. The study provided an effective means for the prediction of fracture strength of porous ceramic structures, thereby facilitating design optimization of scaffolds.

  4. Fracture behaviors of ceramic tissue scaffolds for load bearing applications.

    PubMed

    Entezari, Ali; Roohani-Esfahani, Seyed-Iman; Zhang, Zhongpu; Zreiqat, Hala; Dunstan, Colin R; Li, Qing

    2016-01-01

    Healing large bone defects, especially in weight-bearing locations, remains a challenge using available synthetic ceramic scaffolds. Manufactured as a scaffold using 3D printing technology, Sr-HT-Gahnite at high porosity (66%) had demonstrated significantly improved compressive strength (53 ± 9 MPa) and toughness. Nevertheless, the main concern of ceramic scaffolds in general remains to be their inherent brittleness and low fracture strength in load bearing applications. Therefore, it is crucial to establish a robust numerical framework for predicting fracture strengths of such scaffolds. Since crack initiation and propagation plays a critical role on the fracture strength of ceramic structures, we employed extended finite element method (XFEM) to predict fracture behaviors of Sr-HT-Gahnite scaffolds. The correlation between experimental and numerical results proved the superiority of XFEM for quantifying fracture strength of scaffolds over conventional FEM. In addition to computer aided design (CAD) based modeling analyses, XFEM was conducted on micro-computed tomography (μCT) based models for fabricated scaffolds, which took into account the geometric variations induced by the fabrication process. Fracture strengths and crack paths predicted by the μCT-based XFEM analyses correlated well with relevant experimental results. The study provided an effective means for the prediction of fracture strength of porous ceramic structures, thereby facilitating design optimization of scaffolds. PMID:27403936

  5. Design Methods for Load-bearing Elements from Crosslaminated Timber

    NASA Astrophysics Data System (ADS)

    Vilguts, A.; Serdjuks, D.; Goremikins, V.

    2015-11-01

    Cross-laminated timber is an environmentally friendly material, which possesses a decreased level of anisotropy in comparison with the solid and glued timber. Cross-laminated timber could be used for load-bearing walls and slabs of multi-storey timber buildings as well as decking structures of pedestrian and road bridges. Design methods of cross-laminated timber elements subjected to bending and compression with bending were considered. The presented methods were experimentally validated and verified by FEM. Two cross-laminated timber slabs were tested at the action of static load. Pine wood was chosen as a board's material. Freely supported beam with the span equal to 1.9 m, which was loaded by the uniformly distributed load, was a design scheme of the considered plates. The width of the plates was equal to 1 m. The considered cross-laminated timber plates were analysed by FEM method. The comparison of stresses acting in the edge fibres of the plate and the maximum vertical displacements shows that both considered methods can be used for engineering calculations. The difference between the results obtained experimentally and analytically is within the limits from 2 to 31%. The difference in results obtained by effective strength and stiffness and transformed sections methods was not significant.

  6. 3D Printing and Biofabrication for Load Bearing Tissue Engineering.

    PubMed

    Jeong, Claire G; Atala, Anthony

    2015-01-01

    Cell-based direct biofabrication and 3D bioprinting is becoming a dominant technological platform and is suggested as a new paradigm for twenty-first century tissue engineering. These techniques may be our next step in surpassing the hurdles and limitations of conventional scaffold-based tissue engineering, and may offer the industrial potential of tissue engineered products especially for load bearing tissues. Here we present a topically focused review regarding the fundamental concepts, state of the art, and perspectives of this new technology and field of biofabrication and 3D bioprinting, specifically focused on tissue engineering of load bearing tissues such as bone, cartilage, osteochondral and dental tissue engineering.

  7. 3D Printing and Biofabrication for Load Bearing Tissue Engineering.

    PubMed

    Jeong, Claire G; Atala, Anthony

    2015-01-01

    Cell-based direct biofabrication and 3D bioprinting is becoming a dominant technological platform and is suggested as a new paradigm for twenty-first century tissue engineering. These techniques may be our next step in surpassing the hurdles and limitations of conventional scaffold-based tissue engineering, and may offer the industrial potential of tissue engineered products especially for load bearing tissues. Here we present a topically focused review regarding the fundamental concepts, state of the art, and perspectives of this new technology and field of biofabrication and 3D bioprinting, specifically focused on tissue engineering of load bearing tissues such as bone, cartilage, osteochondral and dental tissue engineering. PMID:26545741

  8. Thermal coupon testing of Load-Bearing Multilayer Insulation

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Heckle, K. W.; Hurd, J.

    2014-01-01

    Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

  9. Determination of Load Bearing Capacity for Spatial Joint with Steel Angle Brackets

    NASA Astrophysics Data System (ADS)

    Sejkot, P.; Ormarsson, S.; Vessby, J.; Kuklík, P.

    2015-11-01

    The design of spatial connections in load bearing timber structures with steel angle brackets has insufficient support in the existing design standards. Therefore, research has been necessary to improve this state of the art. In the current paper an experimental study on two designs of angle brackets is presented and the results from full-scale experiments are compared to numerical and analytical computational models.

  10. Out of plane analysis for composite structures

    NASA Technical Reports Server (NTRS)

    Paul, P. C.; Saff, C. R.; Sanger, Kenneth B.; Mahler, M. A.; Kan, Han Pin; Kautz, Edward F.

    1990-01-01

    Simple two dimensional analysis techniques were developed to aid in the design of strong joints for integrally stiffened/bonded composite structures subjected to out of plane loads. It was found that most out of plane failures were due to induced stresses arising from rapid changes in load path direction or geometry, induced stresses due to changes in geometry caused by buckling, or direct stresses produced by fuel pressure or bearing loads. While the analysis techniques were developed to address a great variety of out of plane loading conditions, they were primarily derived to address the conditions described above. The methods were developed and verified using existing element test data. The methods were demonstrated using the data from a test failure of a high strain wingbox that was designed, built, and tested under a previous program. Subsequently, a set of design guidelines were assembled to assist in the design of safe, strong integral composite structures using the analysis techniques developed.

  11. Polymeric biomaterials for load-bearing medical devices

    NASA Astrophysics Data System (ADS)

    Pruitt, Lisa; Furmanski, Jevan

    2009-09-01

    This paper aims to give a broad overview of the challenges that are faced in load-bearing medical devices and focuses specifically on the challenges faced in utilizing polymeric materials in such applications. Three specific cases are given in the field of polymeric biomaterials. These cases build in complexity and initiate with examination of the evolution of intravascular catheter design in which the materials, properties, and processing have been optimized to develop a system that can be used in an angioplasty procedure with little concern of clinical failure.

  12. Human footprint variation while performing load bearing tasks.

    PubMed

    Wall-Scheffler, Cara M; Wagnild, Janelle; Wagler, Emily

    2015-01-01

    Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint's maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations.

  13. Evacuated load-bearing high performance insulation study

    NASA Technical Reports Server (NTRS)

    Parmley, R. T.; Cunnington, G. R.

    1977-01-01

    A light weight, vacuum jacketed, load bearing cryogenic insulation system was developed and tested on a 1.17-m (46-in.) spherical test tank. The vacuum jacket consists of 0.08 mm (0.003 in.) thick 321 stainless steel formed into a wedge design that allows elastic jacket movements as the tank shrinks (cools) or expands (warms up or is pressurized). Hollow glass spheres, approximately 80 micrometers in diameter with a bulk density of 0.069 g/cc (4.3 lb cubic foot), provide the insulating qualities and one atmosphere load bearing capability required. The design, fabrication, and test effort developed the manufacturing methods and engineering data needed to scale the system to other tank sizes, shapes, and applications. The program demonstrated that thin wall jackets can be formed and welded to maintain the required vacuum level of .013 Pa yet flex elastically for multiple reuses. No significant shifting or breakage of the microspheres occurred after 13 simulated Space Tug flight cycles on the test tank and a hundred 1 atmosphere load cycles in a flat plate calorimeter. The test data were then scaled to the Space Tug LO2 and LH2 tanks, and weight, thermal performance, payload performance, and costs were compared with a helium purged multilayer insulation system.

  14. Human Footprint Variation while Performing Load Bearing Tasks

    PubMed Central

    Wall-Scheffler, Cara M.; Wagnild, Janelle; Wagler, Emily

    2015-01-01

    Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint’s maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations. PMID:25738496

  15. Load-bearing properties of minimal-invasive monolithic lithium disilicate and zirconia occlusal onlays: finite element and theoretical analyses

    PubMed Central

    Ma, Li; Guess, Petra C.; Zhang, Yu

    2013-01-01

    Objectives The aim of this study was to test the hypothesis that monolithic lithium disilicate glass-ceramic occlusal onlay can exhibit a load-bearing capacity that approaches monolithic zirconia, due to a smaller elastic modulus mismatch between the lithium disilicate and its supporting tooth structure relative to zirconia. Methods Ceramic occlusal onlays of various thicknesses cemented to either enamel or dentin were considered. Occlusal load was applied through an enamel-like deformable indenter or a control rigid indenter. Flexural tensile stress at the ceramic intaglio (cementation) surface—a cause for bulk fracture of occlusal onlays—was rigorously analyzed using finite element analysis and classical plate-on-foundation theory. Results When bonded to enamel (supported by dentin), the load-bearing capacity of lithium disilicate can approach 75% of that of zirconia, despite the flexural strength of lithium disilicate (400 MPa) being merely 40% of zirconia (1000 MPa). When bonded to dentin (with the enamel completely removed), the load-bearing capacity of lithium disilicate is about 57% of zirconia, still significantly higher than the anticipated value based on its strength. Both ceramics show slightly higher load-bearing capacity when loaded with a deformable indenter (enamel, glass-ceramic, or porcelain) rather than a rigid indenter. Significance When supported by enamel, the load-bearing property of minimally invasive lithium disilicate occlusal onlays (0.6 to 1.4 mm thick) can exceed 70% of that of zircona. Additionally, a relatively weak dependence of fracture load on restoration thickness indicates that a 1.2 mm thin lithium disilicate onlay can be as fracture resistant as its 1.6 mm counterpart. PMID:23683531

  16. Plane mixing layer vortical structure kinematics

    NASA Technical Reports Server (NTRS)

    Leboeuf, Richard L.

    1993-01-01

    The objective of the current project was to experimentally investigate the structure and dynamics of the streamwise vorticity in a plane mixing layer. The first part of this research program was intended to clarify whether the observed decrease in mean streamwise vorticity in the far-field of mixing layers is due primarily to the 'smearing' caused by vortex meander or to diffusion. Two-point velocity correlation measurements have been used to show that there is little spanwise meander of the large-scale streamwise vortical structure. The correlation measurements also indicate a large degree of transverse meander of the streamwise vorticity which is not surprising since the streamwise vorticity exists in the inclined braid region between the spanwise vortex core regions. The streamwise convection of the braid region thereby introduces an apparent transverse meander into measurements using stationary probes. These results corroborated with estimated secondary velocity profiles in which the streamwise vorticity produces a signature which was tracked in time.

  17. Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.

    PubMed

    Anton, Steven R; Erturk, Alper; Inman, Daniel

    2012-06-01

    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads.

  18. Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.

    PubMed

    Anton, Steven R; Erturk, Alper; Inman, Daniel

    2012-06-01

    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads. PMID:22711404

  19. High strength, surface porous polyether-ether-ketone for load-bearing orthopaedic implants

    PubMed Central

    Evans, Nathan T.; Torstrick, F. Brennan; Lee, Christopher S.D.; Dupont, Kenneth M.; Safranski, David L.; Chang, W. Allen; Macedo, Annie E.; Lin, Angela; Boothby, Jennifer M.; Whittingslow, Daniel C.; Carson, Robert A.; Guldberg, Robert E.; Gall, Ken

    2015-01-01

    Despite its widespread clinical use in load-bearing orthopaedic implants, polyether-ether-ketone (PEEK) is often associated with poor osseointegration. In this study, a surface porous PEEK material (PEEK-SP) was created using a melt extrusion technique. The porous layer thickness was 399.6±63.3 µm and possessed a mean pore size of 279.9±31.6 µm, strut spacing of 186.8±55.5 µm, porosity of 67.3±3.1%, and interconnectivity of 99.9±0.1%. Monotonic tensile tests showed that PEEK-SP preserved 73.9% of the strength (71.06±2.17 MPa) and 73.4% of the elastic modulus (2.45±0.31 GPa) of as-received, injection molded PEEK. PEEK-SP further demonstrated a fatigue strength of 60.0 MPa at one million cycles, preserving 73.4% of the fatigue resistance of injection molded PEEK. Interfacial shear testing showed the pore layer shear strength to be 23.96±2.26 MPa. An osseointegration model in the rat revealed substantial bone formation within the pore layer at 6 and 12 weeks via µCT and histological evaluation. Ingrown bone was more closely apposed to the pore wall and fibrous tissue growth was reduced in PEEK-SP when compared to non-porous PEEK controls. These results indicate that PEEK-SP could provide improved osseointegration while maintaining the structural integrity necessary for load-bearing orthopaedic applications. PMID:25463499

  20. Application of a load-bearing passive and active vibration isolation system in hydraulic drives

    NASA Astrophysics Data System (ADS)

    Unruh, Oliver; Haase, Thomas; Pohl, Martin

    2016-09-01

    Hydraulic drives are widely used in many engineering applications due to their high power to weight ratio. The high power output of the hydraulic drives produces high static and dynamic reaction forces and moments which must be carried by the mounts and the surrounding structure. A drawback of hydraulic drives based on rotating pistons consists in multi-tonal disturbances which propagate through the mounts and the load bearing structure and produce structure borne sound at the surrounding structures and cavities. One possible approach to overcome this drawback is to use an optimised mounting, which combines vibration isolation in the main disturbance direction with the capability to carry the reaction forces and moments. This paper presents an experimental study, which addresses the vibration isolation performance of an optimised mounting. A dummy hydraulic drive is attached to a generic surrounding structure with optimised mounting and excited by multiple shakers. In order to improve the performance of the passive vibration isolation system, piezoelectric transducers are applied on the mounting and integrated into a feed-forward control loop. It is shown that the optimised mounting of the hydraulic drive decreases the vibration transmission to the surrounding structure by 8 dB. The presented study also reveals that the use of the active control system leads to a further decrease of vibration transmission of up to 14 dB and also allows an improvement of the vibration isolation in an additional degree of freedom and higher harmonic frequencies.

  1. 8. Interior of Building 1015 (land plane hangar), structural detail, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Interior of Building 1015 (land plane hangar), structural detail, looking northeast - Naval Air Station Chase Field, Building 1015, Byrd Street, .82 mile South-southeast of intersection of Texas State Highway 202 & Independence Street, Beeville, Bee County, TX

  2. 7. Interior of Building 1015 (land plane hangar), structural detail, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Interior of Building 1015 (land plane hangar), structural detail, looking northeast - Naval Air Station Chase Field, Building 1015, Byrd Street, .82 mile South-southeast of intersection of Texas State Highway 202 & Independence Street, Beeville, Bee County, TX

  3. Tank Applied Testing of Load-Bearing Multilayer Insulation (LB-MLI)

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley L.; Valenzuela, Juan G.; Feller, Jerr; Plachta, Dave

    2014-01-01

    The development of long duration orbital cryogenic storage systems will require the reduction of heat loads into the storage tank. In the case of liquid hydrogen, complete elimination of the heat load at 20 K is currently impractical due to the limitations in lift available on flight cryocoolers. In order to reduce the heat load, without having to remove heat at 20 K, the concept of Reduced Boil-Off uses cooled shields within the insulation system at approximately 90 K. The development of Load-Bearing Multilayer Insulation (LB-MLI) allowed the 90 K shield with tubing and cryocooler attachments to be suspended within the MLI and still be structurally stable. Coupon testing both thermally and structurally were performed to verify that the LB-MLI should work at the tank applied level. Then tank applied thermal and structural (acoustic) testing was performed to demonstrate the functionality of the LB-MLI as a structural insulation system. The LB-MLI showed no degradation of thermal performance due to the acoustic testing and showed excellent thermal performance when integrated with a 90 K class cryocooler on a liquid hydrogen tank.

  4. Tank Applied Testing of Load-Bearing Multilayer Insulation (LB-MLI)

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley L.; Valenzuela, Juan G.; Feller, Jeffrey R.; Plachta, David W.

    2014-01-01

    The development of long duration orbital cryogenic storage systems will require the reduction of heat loads into the storage tank. In the case of liquid hydrogen, complete elimination of the heat load at 20 K is currently impractical due to the limitations in lift available on flight cryocoolers. In order to reduce the heat load, without having to remove heat at 20 K, the concept of Reduced Boil-Off uses cooled shields within the insulation system at approximately 90 K. The development of Load-Bearing Multilayer Insulation (LB-MLI) allowed the 90 K shield with tubing and cryocooler attachments to be suspended within the MLI and still be structurally stable. Coupon testing, both thermal and structural was performed to verify that the LB-MLI should work at the tank applied level. Then tank applied thermal and structural (acoustic) testing was performed to demonstrate the functionality of the LB-MLI as a structural insulation system. The LB-MLI showed no degradation of thermal performance due to the acoustic testing and showed excellent thermal performance when integrated with a 90 K class cryocooler on a liquid hydrogen tank.

  5. Protein viscosity, mineral fraction and staggered architecture cooperatively enable the fastest stress wave decay in load-bearing biological materials.

    PubMed

    Qwamizadeh, Mahan; Zhang, Zuoqi; Zhou, Kun; Zhang, Yong Wei

    2016-07-01

    One of the key functions of load-bearing biological materials, such as bone, dentin and sea shell, is to protect their inside fragile organs by effectively damping dynamic impact. How those materials achieve this remarkable function remains largely unknown. Using systematic finite element analyses, we study the stress wave propagation and attenuation in cortical bone at the nanoscale as a model material to examine the effects of protein viscosity, mineral fraction and staggered architecture on the elastic wave decay. It is found that the staggered arrangement, protein viscosity and mineral fraction work cooperatively to effectively attenuate the stress wave. For a typical mineral volume fraction and protein viscosity, an optimal staggered nanostructure with specific feature sizes and layouts is able to give rise to the fastest stress wave decay, and the optimal aspect ratio and thickness of mineral platelets are in excellent agreement with experimental measurements. In contrary, as the mineral volume fraction or the protein viscosity goes much higher, the structural arrangement is seen having trivial effect on the stress wave decay, suggesting that the damping properties of the composites go into the structure-insensitive regime from the structure-sensitive regime. These findings not only significantly add to our understanding of the structure-function relationship of load-bearing biological materials, and but also provide useful guidelines for the design of bio-inspired materials with superior resistance to impact loading.

  6. ON THE BIOMECHANICAL FUNCTION OF SCAFFOLDS FOR ENGINEERING LOAD BEARING SOFT TISSUES

    PubMed Central

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

    2010-01-01

    Replacement or regeneration of load bearing soft tissues has long been the impetus for the development bioactive materials. While maturing, current efforts continue to be confounded by our lack of understanding of the intricate multi-scale hierarchical arrangements and interactions typically found in native tissues. The current state of the art in biomaterial processing enables a degree of controllable microstructure that can be used for the development of model systems to deduce fundamental biological implications of matrix morphologies on cell function. Furthermore, the development of computational frameworks which allow for the simulation of experimentally derived observations represents a positive departure from what has mostly been an empirically driven field, enabling a deeper understanding of the highly complex biological mechanisms we wish to ultimately emulate. Ongoing research is actively pursuing new materials and processing methods to control material structure down to the micro-scale to sustain or improve cell viability, guide tissue growth, and provide mechanical integrity all while exhibiting the capacity to degrade in a controlled manner. The purpose of this review is not to focus solely on material processing but to assess the ability of these techniques to produce mechanically sound tissue surrogates, highlight the unique structural characteristics produced in these materials, and discuss how this translates to distinct macroscopic biomechanical behaviors. PMID:20060509

  7. Two-plane symmetry in the structural organization of man.

    PubMed

    Ermolenko, A E

    2005-01-01

    Manifestations of symmetry in the human structural organization in ontogenesis and phylogenetic development are analysed. A concept of macrobiocrystalloid with inherent complex symmetry is proposed for the description of the human organism in its integrity. The symmetry can be characterized as two-plane radial (quadrilateral), where the planar symmetry is predominant while the layout of organs of radial symmetry is subordinated to it. Out of the two planes of symmetry (sagittal and horizontal), the sagittal plane is predominant: (a) the location of the organs is governed by two principles: in compliance with the symmetry planes and in compliance with the radial symmetry around cavities; (b) the location of the radial symmetry organs is also governed by the principle of two-plane symmetry; (c) out of the four antimeres of two-plane symmetry, two are paired while the other two have merged into one organ; (d) some organs which are antimeres relative to the horizontal plane are located at the cranial end of the organism (sensory organs, cerebrum-cerebellum, heart-spleen and others). The two-plane symmetry is formed by two mechanisms--(a) the impact of morphogenetic fields of the whole crystalloid organism during embriogenesis and (b) genetic mechanisms of the development of chromosomes having two-plane symmetry. When comparing mineral and biological entities we should consider not the whole immobile crystal but only the active superficial part of a growing or dissolving crystal, the interface between the crystal surface and the crystal-forming environment which directly controls crystal growth and adapts itself to it, as well as crystal feed stock expressed in the structure of concentration flows. The symmetry of the chromosome, of the embrion at the early stages of cell cleavage as well as of some organs and systems in their phylogenetic development is described.

  8. Glide planes symmetry in the organization of some sulfide structures

    NASA Astrophysics Data System (ADS)

    Borisov, S. V.; Magarill, S. A.; Pervukhina, N. V.

    2016-03-01

    The role of glide planes in the organization of structures is shown based on a crystallographic analysis of the monoclinic structures of TlAs3S5 and Tl2(As,Sb)3S13 sulfides. In the first structure, cations and anions form systems (with identical geometries) of two face-centered sublattices, linked by the c plane, with the effect of unified "two-dimensional" (2D) ordering. The second structure, exhibiting signs of order-disorder (OD) type, is interpreted as a superposition of two noncentrosymmetric components with independent cation and anion sublattices, which, however, also form a regular 2D order due to the n plane. The stabilizing role of Tl cations in the geometry of cation matrices is indicated.

  9. Porous poly(ε-caprolactone) scaffolds for load-bearing tissue regeneration: solventless fabrication and characterization.

    PubMed

    Allaf, Rula M; Rivero, Iris V; Abidi, Noureddine; Ivanov, Ilia N

    2013-08-01

    Three-dimensional interconnected porous poly(ε-caprolactone) scaffolds have been prepared by a novel solventless scaffold fabrication approach combining cryomilling and compression molding/porogen leaching techniques. This study investigated the effects of processing parameters on scaffold morphology and properties for tissue regeneration. Specifically, the effects of molding temperature, cryomilling time, and porogen mix were examined. Fifty percentage of porous scaffolds were fabricated with a range of properties: mean pore size from ∼40 to 125 μm, water uptake from ∼50 to 86%, compressive modulus from ∼45 to 84 MPa, and compressive strength at 10% strain from ∼3 to 4 MPa. Addition of 60 wt % NaCl salt resulted in a ∼50% increase in porosity in multimodal pore-size structures that depended on the method of NaCl addition. Water uptake ranged from ∼61 to 197%, compressive modulus from ∼4 to 8.6 MPa, and compressive strength at 10% strain from ∼0.36 to 0.40 MPa. Results suggest that this approach provides a controllable strategy for the design and fabrication of 3D interconnected porous biodegradable scaffolds for load-bearing tissue regeneration.

  10. Load bearing and stiffness tailored NiTi implants produced by additive manufacturing: a simulation study

    NASA Astrophysics Data System (ADS)

    Rahmanian, Rasool; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael; Elahinia, Mohammad

    2014-03-01

    Common metals for stable long-term implants (e.g. stainless steel, Titanium and Titanium alloys) are much stiffer than spongy cancellous and even stiffer than cortical bone. When bone and implant are loaded this stiffness mismatch results in stress shielding and as a consequence, degradation of surrounding bony structure can lead to disassociation of the implant. Due to its lower stiffness and high reversible deformability, which is associated with the superelastic behavior, NiTi is an attractive biomaterial for load bearing implants. However, the stiffness of austenitic Nitinol is closer to that of bone but still too high. Additive manufacturing provides, in addition to the fabrication of patient specific implants, the ability to solve the stiffness mismatch by adding engineered porosity to the implant. This in turn allows for the design of different stiffness profiles in one implant tailored to the physiological load conditions. This work covers a fundamental approach to bring this vision to reality. At first modeling of the mechanical behavior of different scaffold designs are presented as a proof of concept of stiffness tailoring. Based on these results different Nitinol scaffolds can be produced by additive manufacturing.

  11. Design, fabrication and test of Load Bearing multilayer insulation to support a broad area cooled shield

    NASA Astrophysics Data System (ADS)

    Dye, S. A.; Johnson, W. L.; Plachta, D. W.; Mills, G. L.; Buchanan, L.; Kopelove, A. B.

    2014-11-01

    Improvements in cryogenic propellant storage are needed to achieve reduced or Zero Boil Off of cryopropellants, critical for long duration missions. Techniques for reducing heat leak into cryotanks include using passive multi-layer insulation (MLI) and vapor cooled or actively cooled thermal shields. Large scale shields cannot be supported by tank structural supports without heat leak through the supports. Traditional MLI also cannot support shield structural loads, and separate shield support mechanisms add significant heat leak. Quest Thermal Group and Ball Aerospace, with NASA SBIR support, have developed a novel Load Bearing multi-layer insulation (LBMLI) capable of self-supporting thermal shields and providing high thermal performance. We report on the development of LBMLI, including design, modeling and analysis, structural testing via vibe and acoustic loading, calorimeter thermal testing, and Reduced Boil-Off (RBO) testing on NASA large scale cryotanks. LBMLI uses the strength of discrete polymer spacers to control interlayer spacing and support the external load of an actively cooled shield and external MLI. Structural testing at NASA Marshall was performed to beyond maximum launch profiles without failure. LBMLI coupons were thermally tested on calorimeters, with superior performance to traditional MLI on a per layer basis. Thermal and structural tests were performed with LBMLI supporting an actively cooled shield, and comparisons are made to the performance of traditional MLI and thermal shield supports. LBMLI provided a 51% reduction in heat leak per layer over a previously tested traditional MLI with tank standoffs, a 38% reduction in mass, and was advanced to TRL5. Active thermal control using LBMLI and a broad area cooled shield offers significant advantages in total system heat flux, mass and structural robustness for future Reduced Boil-Off and Zero Boil-Off cryogenic missions with durations over a few weeks.

  12. Event Tracking Model of Adhesion Identifies Load-bearing Bonds in Rolling Leukocytes

    PubMed Central

    POSPIESZALSKA, MARIA K.; ZARBOCK, ALEXANDER; PICKARD, JOHN E.; LEY, KLAUS

    2009-01-01

    Objectives P-selectin binding to P-selectin glycoprotein ligand (PSGL)-1 mediates leukocyte rolling under conditions of inflammation and injury. The objectives were to develop an efficient, high temporal resolution model for direct simulation of leukocyte rolling, and then to conduct a study of load-bearing bonds using the model. Methods A stochastic π-calculus-driven Event Tracking Model of Adhesion was developed and compared with experimental data. Multiple simulations for each case were conducted to obtain high confidence numerical characteristics of leukocyte rolling. Results Leukocyte rolling and the underlying P-selectin—PSGL-1 bonds were studied under low wall shear rate (25-50 s-1) conditions from measured parameters of leukocyte rolling and bond properties. For the first time, the location, number, lifetime, history, and kinetics of load-bearing bonds and their influence on cell rolling are identified. Instantaneous cell displacements, translational and rotational velocities, and cell-endothelium distances are derived. The model explains the commonly observed “stop-start” type rolling behavior and reveals that a few load-bearing bonds are sufficient to support rolling while a large number of bonds dissociate before becoming load-bearing. Conclusions The presented model provides a method for precise and direct simulation of leukocyte rolling, and sets a foundation upon which further refinements can be introduced. PMID:19023690

  13. Structures technology applications for the National AeroSpace Plane

    NASA Technical Reports Server (NTRS)

    Little, T. E.

    1992-01-01

    The National AeroSpace Plane (NASP) presents a unique set of very complex structural problems that challenge our computational capabilities. Complex analyses are required in the conceptual design phase to achieve sufficient accuracy to address the extreme load conditions and to adequately evaluate vehicle weight. The computational capability must be available to perform these analyses in a rapid manner to accommodate the design process.

  14. Effect of nanofillers on the physico-mechanical properties of load bearing bone implants.

    PubMed

    Michael, Feven Mattews; Khalid, Mohammad; Walvekar, Rashmi; Ratnam, Chantara Thevy; Ramarad, Suganti; Siddiqui, Humaira; Hoque, M Enamul

    2016-10-01

    Bones are nanocomposites consisting of a collagenous fibre network, embedded with calcium phosphates mainly hydroxyapatite (HA) nanocrystallites. As bones are subjected to continuous loading and unloading process every day, they often tend to become prone to fatigue and breakdown. Therefore, this review addresses the use of nanocomposites particularly polymers reinforced with nanoceramics that can be used as load bearing bone implants. Further, nanocomposite preparation and dispersion modification techniques have been highlighted along with thorough discussion on the influence that various nanofillers have on the physico-mechanical properties of nanocomposites in relation to that of natural bone properties. This review updates the nanocomposites that meet the physico-mechanical properties (strength and elasticity) as well as biocompatibility requirement of a load bearing bone implant and also attempts to highlight the gaps in the reported studies to address the fatigue and creep properties of the nanocomposites. PMID:27287178

  15. Direct Ink Writing of Highly Porous and Strong Glass Scaffolds for Load-bearing Bone Defects Repair and Regeneration

    PubMed Central

    Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P.

    2011-01-01

    The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires development of porous and high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work, bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inkswere optimized for the printing of features as fine as 30 μm and of the three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds show a compressive strength (136 ± 22 MPa) comparable to that of human cortical bone (100-150 MPa), while the porosity (60%) is in the range of that of trabecular bone (50-90%).The strength is ~100 times that of polymer scaffolds and 4–5 times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in an SBF, the value (77 MPa) is still far above that of trabecular bone after three weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

  16. Surface modification and fatigue behavior of nitinol for load bearing implants

    NASA Astrophysics Data System (ADS)

    Bernard, Sheldon A.

    Musculoskeletal disorders are recognized amongst the most significant human health problems that exist today. Even though considerable research and development has gone towards understanding musculoskeletal disorders, there is still lack of bone replacement materials that are appropriate for restoring lost structures and functions, particularly for load-bearing applications. Many materials on the market today, such as titanium and stainless steel, suffer from significantly higher modulus than natural bone and low bioactivity leading to stress shielding and implant loosening over longer time use. Nitinol (NiTi) is an equiatomic intermetallic compound of nickel and titanium whose unique biomechanical and biological properties contributed to its increasing use as a biomaterial. An innovative method for creating dense and porous net shape NiTi alloy parts has been developed to improve biological properties while maintaining comparable or better mechanical properties than commercial materials that are currently in use. Laser engineered net shaping (LENS(TM)) and surface electrochemistry modification was used to create dense/porous samples and micro textured surfaces on NiTi parts, respectively. Porous implants are known to promote cell adhesion and have a low elastic modulus, a combination that can significantly increase the life of an implant. However, porosity can significantly reduce the fatigue life of an implant, and very little work has been reported on the fatigue behavior of bulk porous metals, specifically on porous nitinol alloy. High-cycle rotating bending and compression-compression fatigue behavior of porous NiTi fabricated using LENS(TM) were studied. In cyclic compression loading, plastic strain increased with increasing porosity and it was evident that maximum strain was achieved during the first 50000 cycles and remained constant throughout the remaining loading. No failures were observed due to loading up to 150% of the yield strength. When subjected

  17. Strained layer superlattice focal plane array having a planar structure

    DOEpatents

    Kim, Jin K; Carroll, Malcolm S; Gin, Aaron; Marsh, Phillip F; Young, Erik W; Cich, Michael J

    2012-10-23

    An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

  18. A Curved, Elastostatic Boundary Element for Plane Anisotropic Structures

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S.; Klang, Eric C.

    2001-01-01

    The plane-stress equations of linear elasticity are used in conjunction with those of the boundary element method to develop a novel curved, quadratic boundary element applicable to structures composed of anisotropic materials in a state of plane stress or plane strain. The curved boundary element is developed to solve two-dimensional, elastostatic problems of arbitrary shape, connectivity, and material type. As a result of the anisotropy, complex variables are employed in the fundamental solution derivations for a concentrated unit-magnitude force in an infinite elastic anisotropic medium. Once known, the fundamental solutions are evaluated numerically by using the known displacement and traction boundary values in an integral formulation with Gaussian quadrature. All the integral equations of the boundary element method are evaluated using one of two methods: either regular Gaussian quadrature or a combination of regular and logarithmic Gaussian quadrature. The regular Gaussian quadrature is used to evaluate most of the integrals along the boundary, and the combined scheme is employed for integrals that are singular. Individual element contributions are assembled into the global matrices of the standard boundary element method, manipulated to form a system of linear equations, and the resulting system is solved. The interior displacements and stresses are found through a separate set of auxiliary equations that are derived using an Airy-type stress function in terms of complex variables. The capabilities and accuracy of this method are demonstrated for a laminated-composite plate with a central, elliptical cutout that is subjected to uniform tension along one of the straight edges of the plate. Comparison of the boundary element results for this problem with corresponding results from an analytical model show a difference of less than 1%.

  19. Stretchable and transparent electrodes based on in-plane structures.

    PubMed

    Kim, Kukjoo; Kim, Joohee; Hyun, Byung Gwan; Ji, Sangyoon; Kim, So-Yun; Kim, Sungwon; An, Byeong Wan; Park, Jang-Ung

    2015-09-21

    Stretchable electronics has attracted great interest with compelling potential applications that require reliable operation under mechanical deformation. Achieving stretchability in devices, however, requires a deeper understanding of nanoscale materials and mechanics beyond the success of flexible electronics. In this regard, tremendous research efforts have been dedicated toward developing stretchable electrodes, which are one of the most important building blocks for stretchable electronics. Stretchable transparent thin-film electrodes, which retain their electrical conductivity and optical transparency under mechanical deformation, are particularly important for the favourable application of stretchable devices. This minireview summarizes recent advances in stretchable transparent thin-film electrodes, especially employing strategies based on in-plane structures. Various approaches using metal nanomaterials, carbon nanomaterials, and their hybrids are described in terms of preparation processes and their optoelectronic/mechanical properties. Some challenges and perspectives for further advances in stretchable transparent electrodes are also discussed. PMID:26287668

  20. HERSCHEL GALACTIC PLANE SURVEY OF [N ii] FINE STRUCTURE EMISSION

    SciTech Connect

    Goldsmith, Paul F.; Yıldız, Umut A.; Langer, William D.; Pineda, Jorge L.

    2015-12-01

    We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N ii]) at 122 and 205 μm. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10{sup −8}–10{sup −7} Wm{sup −2} sr{sup −1} level over the range –60° ≤ l ≤ 60°. The rms of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [N ii] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10–50 cm{sup −3} with an average value of 29 cm{sup −3} and N{sup +} column densities 10{sup 16}–10{sup 17} cm{sup −2}. [N ii] emission is highly correlated with that of [C ii], and we calculate that between 1/3 and 1/2 of the [C ii] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N ii] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N ii] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H ii regions, and low-filling factor high-density fluctuations of the WIM.

  1. MTF comparisons between mesa and planar focal plane detector structures

    NASA Astrophysics Data System (ADS)

    Perley, Mitchell; Wehner, Justin; Buell, Dave; Micali, Jason; McCorkle, Joe; Rehfield, Mark; Williams, Dave; Dixon, Andrew; Malone, Neil

    2013-09-01

    Raytheon Vision Systems (RVS) has developed scanning, high-speed (<3klps), all digital, with on-chip Analog-to-Digital Conversion (ADC), mid-wave infrared (MWIR 3-5mm) focal plane arrays (FPA) with excellent modulation transfer function (MTF) performance. Using secondary ion mass spectrometry (SIMS) data and detailed models of the mesa geometry, RVS modeled the predicted detector MTF performance of detectors. These detectors have a mesa structure and geometry for improved MTF performance compared to planar HgCdTe and InSb detector structures and other similar detector structures such as nBn. The modeled data is compared to measured MTF data obtained from edge spread measurements and shows good agreement, Figure 1. The measured data was obtained using a custom advanced test set with 1µm precision alignment and automatic data acquisition for report generation in less than five minutes per FPA. The measured MTF values of 83 unique parts, Figure 2, had a standard deviation of 0.0094 and a mean absolute deviation of 0.0066 at half Nyquist frequency, showing excellent process repeatability and a design that supports high MTF with good repeatability.

  2. Silk as a biocohesive sacrificial binder in the fabrication of hydroxyapatite load bearing scaffolds.

    PubMed

    McNamara, Stephanie L; Rnjak-Kovacina, Jelena; Schmidt, Daniel F; Lo, Tim J; Kaplan, David L

    2014-08-01

    Limitations of current clinical methods for bone repair continue to fuel the demand for a high strength, bioactive bone replacement material. Recent attempts to produce porous scaffolds for bone regeneration have been limited by the intrinsic weakness associated with high porosity materials. In this study, ceramic scaffold fabrication techniques for potential use in load-bearing bone repairs have been developed using naturally derived silk from Bombyx mori. Silk was first employed for ceramic grain consolidation during green body formation, and later as a sacrificial polymer to impart porosity during sintering. These techniques allowed preparation of hydroxyapatite (HA) scaffolds that exhibited a wide range of mechanical and porosity profiles, with some displaying unusually high compressive strength up to 152.4 ± 9.1 MPa. Results showed that the scaffolds exhibited a wide range of compressive strengths and moduli (8.7 ± 2.7 MPa to 152.4 ± 9.1 MPa and 0.3 ± 0.1 GPa to 8.6 ± 0.3 GPa) with total porosities of up to 62.9 ± 2.7% depending on the parameters used for fabrication. Moreover, HA-silk scaffolds could be molded into large, complex shapes, and further machined post-sinter to generate specific three-dimensional geometries. Scaffolds supported bone marrow-derived mesenchymal stem cell attachment and proliferation, with no signs of cytotoxicity. Therefore, silk-fabricated HA scaffolds show promise for load bearing bone repair and regeneration needs.

  3. Silk as a biocohesive sacrificial binder in the fabrication of hydroxyapatite load bearing scaffolds

    PubMed Central

    McNamara, Stephanie L.; Rnjak-Kovacina, Jelena; Schmidt, Daniel; Lo, Tim J.; Kaplan, David L.

    2014-01-01

    Limitations of current clinical methods for bone repair continue to fuel the demand for a high strength, bioactive bone replacement material. Recent attempts to produce porous scaffolds for bone regeneration have been limited by the intrinsic weakness associated with high porosity materials. In this study, ceramic scaffold fabrication techniques for potential use in load-bearing bone repairs have been developed using naturally derived silk from Bombyx mori. Silk was first employed for ceramic grain consolidation during green body formation, and later as a sacrificial polymer to impart porosity during sintering. These techniques allowed preparation of hydroxyapatite (HA) scaffolds that exhibited a wide range of mechanical and porosity profiles, with some displaying unusually high compressive strength up to 152.4 ± 9.1 MPa. Results showed that the scaffolds exhibited a wide range of compressive strengths and moduli (8.7 ± 2.7 MPa to 152.4 ± 9.1 MPa and 0.3 ± 0.1 GPa to 8.6 ± 0.3 GPa) with total porosities of up to 62.9 ± 2.7% depending on the parameters used for fabrication. Moreover, HA-silk scaffolds could be molded into large, complex shapes, and further machined post-sinter to generate specific three-dimensional geometries. Scaffolds supported bone marrow-derived mesenchymal stem cell attachment and proliferation, with no signs of cytotoxicity. Therefore, silk-fabricated HA scaffolds show promise for load bearing bone repair and regeneration needs. PMID:24881027

  4. Stress analysis of the space telescope focal plane structure joint

    NASA Technical Reports Server (NTRS)

    Foster, W. A., Jr.; Shoemaker, W. L.

    1985-01-01

    Two major efforts were begun concerning the Space Telescope focal plane structure joint. The 3-D solid finite element modeling of the bipod flexure plate was carried out. Conceptual models were developed for the load transfer through the three major bolts to the flexure plate. The flexure plate drawings were reconstructed using DADAM for the purpose of developing a file from which the coordinates of any point on the flexure plate could be determined and also to locate the attachment points of the various components which connect with the flexure plate. For modeling convenience the CADAM drawing of the flexure plate has been divided into several regions which will be subdivided into finite elements using MSGMESH, which is a finite element mesh generator available with MSC/NASTRAN. In addition to the CADAM work on the flexure plate, an effort was also begun to develop computer aided drawings of the peripheral beam which will be used to assist in modeling the connection between it and the flexure plate.

  5. The Potential of a Clinch-Lock Polymer Metal Hybrid Technology for Use in Load-Bearing Automotive Components

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Sellappan, V.; Arakere, G.; Seyr, Norbert; Obieglo, Andreas; Erdmann, Marc; Holzleitner, Jochen

    2009-10-01

    In order to help meet the needs of automotive original equipment manufacturers and their suppliers for a cost-effective, robust, reliable polymer-metal-hybrid (PMH) technology which can be used for the manufacturing of load-bearing body-in-white (BIW) components and which is compatible with the current BIW manufacturing process chain, a new approach, the so-called direct-adhesion PMH technology, was recently proposed (Grujicic et al., J. Mater. Process. Technol., 2008, 195, p 282-298). Within this approach, the necessary level of polymer-to-metal mechanical interconnectivity is attained through direct adhesion and mechanical interlocking. In the present work, a new concept for mechanical interlocking between the metal and plastics is proposed and analyzed computationally. The approach utilizes some of the ideas used in the spot-clinching joining process and is appropriately named clinch-lock PMH technology. To assess the potential of the clinch-lock approach for providing the required level of metal/polymer mechanical interlocking, a set of finite-element based sheet-metal forming, injection molding and structural mechanics analyses was carried out. The results obtained show that stiffness and buckling resistance levels can be attained which are comparable with those observed in the competing injection overmolding PMH process but with an ~3% lower weight (of the polymer subcomponent) and without the need for holes and for overmolding of the free edges of the metal stamping.

  6. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    PubMed

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375

  7. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    PubMed Central

    Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375

  8. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    PubMed

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  9. Enhancement of entangled porous titanium by BisGMA for load-bearing biomedical applications.

    PubMed

    Liu, Yan; Jiang, Guofeng; He, Guo

    2016-04-01

    The Bisphenol A glycidyl methacrylate (BisGMA) was used as binder to fix the free cross wire nodes in the entangled porous titanium for enhancement. The entangled titanium with 60% porosity after infiltrated with 5-20 vol.% BisGMA had the pore size in the range of 100 μm-400 μm. The enhanced materials with the real porosity of 40-55% exhibited the elastic modulus in the range of 0.4-1.4 GPa and the yielding strength in the range of 12.9-52.5 MPa. Such mechanical properties were comparable with those of cancellous bones, suggesting potentials for load-bearing bio applications. PMID:26838821

  10. Microfabrication of Cell-Laden Hydrogels for Engineering Mineralized and Load Bearing Tissues.

    PubMed

    Li, Chia-Cheng; Kharaziha, Mahshid; Min, Christine; Maas, Richard; Nikkhah, Mehdi

    2015-01-01

    Microengineering technologies and advanced biomaterials have extensive applications in the field of regenerative medicine. In this chapter, we review the integration of microfabrication techniques and hydrogel-based biomaterials in the field of dental, bone, and cartilage tissue engineering. We primarily discuss the major features that make hydrogels attractive candidates to mimic extracellular matrix (ECM), and we consider the benefits of three-dimensional (3D) culture systems for tissue engineering applications. We then focus on the fundamental principles of microfabrication techniques including photolithography, soft lithography and bioprinting approaches. Lastly, we summarize recent research on microengineering cell-laden hydrogel constructs for dental, bone and cartilage regeneration, and discuss future applications of microfabrication techniques for load-bearing tissue engineering.

  11. Transfer matrix approach to propagation of angular plane wave spectra through metamaterial multilayer structures

    NASA Astrophysics Data System (ADS)

    Banerjee, Partha P.; Li, Han; Aylo, Rola; Nehmetallah, Georges

    2011-10-01

    The development of electromagnetic (EM) metamaterials for perfect lensing and optical cloaking has given rise to novel multilayer bandgap structures using stacks of positive and negative index materials. Propagation of a collection of TE or TM plane waves, comprising the angular plane wave spectrum, through such structures is analyzed by using the transfer matrix method (TMM) on every plane wave component. Results obtained from this TMM approach for a Gaussian spectrum are compared with those using standard FEM techniques.

  12. Degradation of Zr-based bulk metallic glasses used in load-bearing implants: A tribocorrosion appraisal.

    PubMed

    Zhao, Guo-Hua; Aune, Ragnhild E; Mao, Huahai; Espallargas, Nuria

    2016-07-01

    Owing to the amorphous structure, Bulk Metallic Glasses (BMGs) have been demonstrating attractive properties for potential biomedical applications. In the present work, the degradation mechanisms of Zr-based BMGs with nominal compositions Zr55Cu30Ni5Al10 and Zr65Cu18Ni7Al10 as potential load-bearing implant material were investigated in a tribocorrosion environment. The composition-dependent micro-mechanical and tribological properties of the two BMGs were evaluated prior to the tribocorrosion tests. The sample Zr65-BMG with a higher Zr content exhibited increased plasticity but relatively reduced wear resistance during the ball-on-disc tests. Both BMGs experienced abrasive wear after the dry wear test under the load of 2N. The cross-sectional subsurface structure of the wear track was examined by Focused Ion Beam (FIB). The electrochemical properties of the BMGs in simulated body fluid were evaluated by means of potentiodynamic polarization and X-ray Photoelectron Spectroscopy (XPS). The spontaneous passivation of Zr-based BMGs in Phosphate Buffer Saline solution was mainly attributed to the highly concentrated zirconium cation (Zr(4+)) in the passive film. The tribocorrosion performance of the BMGs was investigated using a reciprocating tribometer equipped with an electrochemical cell. The more passive nature of the Zr65-BMG had consequently a negative influence on its tribocorrosion resistance, which induced the wear-accelerated corrosion and eventually speeded-up the degradation process. It has been revealed the galvanic coupling was established between the depassivated wear track and the surrounding passive area, which is the main degradation mechanism for the passive Zr65-BMG subjected to the tribocorrosion environment. PMID:26773648

  13. Tailored complex 3D vortex lattice structures by perturbed multiples of three-plane waves.

    PubMed

    Xavier, Jolly; Vyas, Sunil; Senthilkumaran, Paramasivam; Joseph, Joby

    2012-04-20

    As three-plane waves are the minimum number required for the formation of vortex-embedded lattice structures by plane wave interference, we present our experimental investigation on the formation of complex 3D photonic vortex lattice structures by a designed superposition of multiples of phase-engineered three-plane waves. The unfolding of the generated complex photonic lattice structures with higher order helical phase is realized by perturbing the superposition of a relatively phase-encoded, axially equidistant multiple of three noncoplanar plane waves. Through a programmable spatial light modulator assisted single step fabrication approach, the unfolded 3D vortex lattice structures are experimentally realized, well matched to our computer simulations. The formation of higher order intertwined helices embedded in these 3D spiraling vortex lattice structures by the superposition of the multiples of phase-engineered three-plane waves interference is also studied.

  14. Effect of optimum plastic depth on stresses and load-bearing capacity of autofrettaged cylinder

    NASA Astrophysics Data System (ADS)

    Zhu, Ruilin; Zhu, Guolin

    2013-03-01

    Autofrettage is an effective measure to even distribution of stresses and raise load-bearing capacity for (ultra-)high pressure apparatus. Currently, the research on autofrettage has focused mostly on specific engineering problems, while general theoretical study is rarely done. To discover the general law contained in autofrettage theory, by the aid of the authors' previous work and according to the third strength theory, theoretical problems about autofrettage are studied including residual stresses and their equivalent stress, total stresses and their equivalent stress, etc. Because of the equation of optimum depth of plastic zone which is presented in the authors' previous work, the equations for the residual stresses and their equivalent stress as well as the total stress and their equivalent stress are simplified greatly. Thus the law of distribution of the residual stresses and their equivalent stress as well as the total stress and their equivalent stress and the varying tendency of these stresses are discovered. The relation among various parameters are revealed. The safe and optimum load-bearing conditions for cylinders are obtained. According to the results obtained by theoretical analysis, it is shown that if the two parameters, namely ratio of outside to inside radius, k, and depth of plastic zone, k j, meet the equation of optimum depth of plastic zone, when the pressure contained in an autofrettaged cylinder is lower than two times the initial yield pressure of the unautofrettaged cylinder, the equivalent residual stress and the equivalent total stress at the inside surface as well as the elastic-plastic juncture of a cylinder are lower than yield strength. When an autofrettaged cylinder is subjected to just two times the initial yield pressure of the unautofrettaged cylinder, the equivalent total stress within the whole plastic zone is just identically equal to the yield strength, or it is a constant. The proposed research theoretically depicts the

  15. Thermal and structural analyses of variable thickness plane problems

    SciTech Connect

    Wang, Zhibi; Kuzay, T.M.

    1995-07-01

    Finite difference formulations for variable thickness thermal analysis and variable thickness plane stress analysis are presented. In heat transfer analysis, radiation effects and temperature-dependent thermal conductivity are taken into account. While in thermal stress analysis, the thermal expansion coefficient is considered as temperature dependent. An application of the variable thickness window for synchrotron radiation beamline under very strong X-ray is provided.

  16. Lubrication and load-bearing properties of human salivary pellicles adsorbed ex vivo on molecularly smooth substrata.

    PubMed

    Harvey, Neale M; Yakubov, Gleb E; Stokes, Jason R; Klein, Jacob

    2012-01-01

    In a series of Surface Force Balance experiments, material from human whole saliva was adsorbed to molecularly smooth mica substrata (to form an 'adsorbed salivary film'). Measurements were taken of normal (load bearing, F (n)) and shear (frictional, F (s)*) forces between two interacting surfaces. One investigation involved a salivary film formed by overnight adsorption from undiluted, centrifuged saliva, with the adsorbed film rinsed with pure water before measurement. Measurements were taken under pure water and 70 mM NaNO(3). In a second investigation, a film was formed from and measured under a solution of 7% filtered saliva in 10 mM NaNO(3). F (n) results for both systems showed purely repulsive layers, with an uncompressed thickness of 35-70 nm for the diluted saliva investigation and, prior to the application of shear, 11 nm for the rinsed system. F (s)* was essentially proportional to F (n) for all systems and independent of shear speed (in the range 100-2000 nm s(-1)), with coefficients of friction μ ≈ 0.24 and μ ≈ 0.46 for the unrinsed and rinsed systems, respectively. All properties of the rinsed system remained similar when the pure water measurement environment was changed to 70 mM NaNO(3). For all systems studied, shear gave rise to an approximately threefold increase in the range of normal forces, attributed to the ploughing up of adsorbed material during shear to form debris that stood proud of the adsorbed layer. The results provide a microscopic demonstration of the wear process for a salivary film under shear and may be of particular interest for understanding the implications for in vivo oral lubrication under conditions such as rinsing of the mouth cavity. The work is interpreted in light of earlier studies that showed a structural collapse and increase in friction for an adsorbed salivary film in an environment of low ionic strength.

  17. Nano-TiO2 reinforced PEEK/PEI blends as biomaterials for load-bearing implant applications.

    PubMed

    Díez-Pascual, Ana M; Díez-Vicente, Angel L

    2015-03-11

    Biocompatible ternary nanocomposites based on poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI) blends reinforced with bioactive titanium dioxide (TiO2) nanoparticles were fabricated via ultrasonication followed by melt-blending. The developed biomaterials were characterized using FT-IR, SEM, XRD, DSC, TGA, and DMA. Further, their water-absorption, tensile, tribological, dielectric, and antibacterial properties were evaluated. PEI acts as a coupling agent, since it can interact both with PEEK via π-π stacking and polar interactions as well as with the nanoparticles through hydrogen bonding, as corroborated by the FT-IR spectra, which resulted in a homogeneous titania dispersion within the biopolymer blend without applying any particle surface treatment or polymer functionalization. A change from promotion to retardation in the crystallization rate of the matrix was found with increasing TiO2 concentration, while its crystalline structure remained unaltered. The nanoparticles stiffened, strengthened, and toughened the matrix simultaneously, and the optimal properties were achieved at 4.0 wt % TiO2. More interesting, the tensile properties were retained after steam sterilization in an autoclave or exposure to a simulated body fluid (SBF). The nanocomposites also displayed reduced water absorption though higher thermal stability, storage modulus, glass transition temperature, dielectric constant, and dielectric loss compared to the control blend. Further, remarkable enhancements in the tribological properties under both SBF and dry environments were attained. The nanoparticles conferred antibacterial action versus Gram-positive and Gram-negative bacteria in the presence and the absence of UV light, and the highest inhibition was attained at 4.0 wt % nanoparticle concentration. These nanocomposites are expected to be used in long-term load-bearing implant applications. PMID:25706225

  18. Injectable, high modulus, and fatigue resistant composite scaffold for load-bearing soft tissue regeneration.

    PubMed

    Hayami, James W S; Waldman, Stephen D; Amsden, Brian G

    2013-12-01

    High modulus, two-phase, bicontinuous scaffolds were prepared by photocross-linking an aqueous suspension of chondrocytes and N-methacrylate glycol chitosan with a hydrolyzable, hydrophobic, acrylated star-copolymer. Two acrylated star-copolymers were examined: poly(ε-caprolactone-co-d,l-lactide) (5446DLLACL) and poly(ε-caprolactone-co-trimethylene carbonate) (7030TMCCL). The scaffolds were assessed for injectability, two-phase interconnectivity, fatigue resistance, and long-term static culture behavior. The 7030TMCCL scaffolds demonstrated decreased moduli of 17% after 1 × 10(6) cycles at 30% strain and 5% after 56 days in culture, compared to the 5446DLLACL scaffolds, which exhibited decreases of 58 and 68%, respectively. The 7030TMCCL scaffolds accumulated more extracellular matrix after 56 days of culture (GAG: 20.1 ± 1, collagen: 35.5 ± 1.8 μg) compared to 5446DLLACL scaffolds (GAG: 13.2 ± 0.6, collagen: 6.2 ± 3.4 μg). Overall, the 7030TMCCL-based scaffolds were shown to be better suited for use as a load bearing soft tissue scaffold. PMID:24147621

  19. Development of Composite Scaffolds for Load-Bearing Segmental Bone Defects

    PubMed Central

    2013-01-01

    The need for a suitable tissue-engineered scaffold that can be used to heal load-bearing segmental bone defects (SBDs) is both immediate and increasing. During the past 30 years, various ceramic and polymer scaffolds have been investigated for this application. More recently, while composite scaffolds built using a combination of ceramics and polymeric materials are being investigated in a greater number, very few products have progressed from laboratory benchtop studies to preclinical testing in animals. This review is based on an exhaustive literature search of various composite scaffolds designed to serve as bone regenerative therapies. We analyzed the benefits and drawbacks of different composite scaffold manufacturing techniques, the properties of commonly used ceramics and polymers, and the properties of currently investigated synthetic composite grafts. To follow, a comprehensive review of in vivo models used to test composite scaffolds in SBDs is detailed to serve as a guide to design appropriate translational studies and to identify the challenges that need to be overcome in scaffold design for successful translation. This includes selecting the animal type, determining the anatomical location within the animals, choosing the correct study duration, and finally, an overview of scaffold performance assessment. PMID:23984363

  20. An Investigation on Load Bearing Capacities of Cement and Resin Grouted Rock Bolts Installed in Weak Rocks

    NASA Astrophysics Data System (ADS)

    Kalyoncu Erguler, Guzide; Abiddin Erguler, Zeynal

    2015-04-01

    Rock bolts have been considered one of indispensable support method to improve load bearing capacity of many underground engineering projects, and thus, various types of them have been developed until now for different purposes. Although mechanically anchored rock bolts can be successfully installed to prevent structurally controlled instabilities in hard rocks, in comparison with cement and resin grouted rock bolts, these types of anchors are not so effective in weak rocks characterized by relatively low mechanical properties. In order to investigate the applicability and to measure relative performance of cement and resin grouted rock bolts into weak and heavily jointed rock mass, a research program mainly consisting of pull-out tests was performed in a metal mine in Turkey. The rock materials excavated in this underground mining were described as basalt, tuff, ore dominated volcanic rocks and dacite. To achieve more representative results for rock materials found in this mining and openings excavated in varied dimensions, the pull-out tests were conducted on rock bolts used in many different locations where more convergences were measured and deformation dependent instability was expected to cause greater engineering problems. It is well known that the capacity of rock bolts depends on the length, diameter and density of the bolt pattern, and so considering the thickness of plastic zone in the studied openings, the length and diameter of rock bolts were taken as 2.4 m. and 25 mm., respectively. The spacing between rows changed between 70 and 180 cm. In this study, totally twenty five pull-out tests were performed to have a general understanding about axial load bearing capacity and support reaction curves of cement and resin grouted rock bolts. When pull load-displacement curves belongs to cement and resin grouted rock bolts were compared with each other, it was determined that cement grouted rock bolts carry more load ranging between 115.6 kN and 127.5 kN with

  1. Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration

    SciTech Connect

    Gotman, Irena Gutmanas, Elazar Y.; Zaretzky, Asaph; Psakhie, Sergey G.

    2015-10-27

    The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy (Nitinol) scaffolds in a critical-size defect (CSD) model. High strength “trabecular Nitinol” scaffolds were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) annealing of the highly porous Ni foam in Ti powder at 900°C. This was followed by PIRAC nitriding to mitigate the release of potentially toxic Ni ions. Scaffolds phase composition and microstructure were characterized by X-ray diffraction and scanning electron microscopy (SEM/EDS), and their mechanical properties were tested in compression. New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: (i) as produced, (ii) loaded with bone marrow aspirate (BMA), and (iii) biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1–1.5 mm into the scaffold. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.

  2. Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration

    NASA Astrophysics Data System (ADS)

    Gotman, Irena; Zaretzky, Asaph; Psakhie, Sergey G.; Gutmanas, Elazar Y.

    2015-10-01

    The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy (Nitinol) scaffolds in a critical-size defect (CSD) model. High strength "trabecular Nitinol" scaffolds were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) annealing of the highly porous Ni foam in Ti powder at 900°C. This was followed by PIRAC nitriding to mitigate the release of potentially toxic Ni ions. Scaffolds phase composition and microstructure were characterized by X-ray diffraction and scanning electron microscopy (SEM/EDS), and their mechanical properties were tested in compression. New Zealand white rabbits received bone defect in right radius and were divided in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: (i) as produced, (ii) loaded with bone marrow aspirate (BMA), and (iii) biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1-1.5 mm into the scaffold. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.

  3. Grain boundary plane orientation fundamental zones and structure-property relationships

    DOE PAGESBeta

    Homer, Eric R.; Patala, Srikanth; Priedeman, Jonathan L.

    2015-10-26

    Grain boundary plane orientation is a profoundly important determinant of character in polycrystalline materials that is not well understood. This work demonstrates how boundary plane orientation fundamental zones, which capture the natural crystallographic symmetries of a grain boundary, can be used to establish structure-property relationships. Using the fundamental zone representation, trends in computed energy, excess volume at the grain boundary, and temperature-dependent mobility naturally emerge and show a strong dependence on the boundary plane orientation. Analysis of common misorientation axes even suggests broader trends of grain boundary energy as a function of misorientation angle and plane orientation. Due to themore » strong structure-property relationships that naturally emerge from this work, boundary plane fundamental zones are expected to simplify analysis of both computational and experimental data. This standardized representation has the potential to significantly accelerate research in the topologically complex and vast five-dimensional phase space of grain boundaries.« less

  4. Grain boundary plane orientation fundamental zones and structure-property relationships

    SciTech Connect

    Homer, Eric R.; Patala, Srikanth; Priedeman, Jonathan L.

    2015-10-26

    Grain boundary plane orientation is a profoundly important determinant of character in polycrystalline materials that is not well understood. This work demonstrates how boundary plane orientation fundamental zones, which capture the natural crystallographic symmetries of a grain boundary, can be used to establish structure-property relationships. Using the fundamental zone representation, trends in computed energy, excess volume at the grain boundary, and temperature-dependent mobility naturally emerge and show a strong dependence on the boundary plane orientation. Analysis of common misorientation axes even suggests broader trends of grain boundary energy as a function of misorientation angle and plane orientation. Due to the strong structure-property relationships that naturally emerge from this work, boundary plane fundamental zones are expected to simplify analysis of both computational and experimental data. This standardized representation has the potential to significantly accelerate research in the topologically complex and vast five-dimensional phase space of grain boundaries.

  5. Grain Boundary Plane Orientation Fundamental Zones and Structure-Property Relationships

    PubMed Central

    Homer, Eric R.; Patala, Srikanth; Priedeman, Jonathan L.

    2015-01-01

    Grain boundary plane orientation is a profoundly important determinant of character in polycrystalline materials that is not well understood. This work demonstrates how boundary plane orientation fundamental zones, which capture the natural crystallographic symmetries of a grain boundary, can be used to establish structure-property relationships. Using the fundamental zone representation, trends in computed energy, excess volume at the grain boundary, and temperature-dependent mobility naturally emerge and show a strong dependence on the boundary plane orientation. Analysis of common misorientation axes even suggests broader trends of grain boundary energy as a function of misorientation angle and plane orientation. Due to the strong structure-property relationships that naturally emerge from this work, boundary plane fundamental zones are expected to simplify analysis of both computational and experimental data. This standardized representation has the potential to significantly accelerate research in the topologically complex and vast five-dimensional phase space of grain boundaries. PMID:26498715

  6. Load-bearing masonry system adoption and performance: A case study of construction company in a developing country

    NASA Astrophysics Data System (ADS)

    Ramli, Nor Azlinda; Abdullah, Che Sobry; Nawi, Mohd Nasrun Mohd; Bahaudin, Ahmad Yusni

    2016-08-01

    This study addresses the factors that influence the adoption of load-bearing masonry (LBM) system. A case study of the load-bearing masonry (LBM) system adoption is conducted through an interview to explore the situation of the technology adoption in a construction company. The finding indicates the factors influence the adoption of LBM system for the construction company are: organizational resources, usefulness, less maintenance, reduce construction time and cost. From the findings, these factors consistent with previous literature. Furthermore, the performance of the company was measured by looking into the financial and non-financial aspects. The LBM system brings good performance as it increased the profits of the company, a good quality of product and attracts more demand from customers. Thus, these factors should be considered for the other companies that are interested in implementing the LBM system in their projects.

  7. Out-of-plane free vibration analysis of a cable-arch structure

    NASA Astrophysics Data System (ADS)

    Kang, H. J.; Zhao, Y. Y.; Zhu, H. P.

    2013-02-01

    Cable-arch structure has been widely used in many long-span structures such as cable roofs and cable-stayed arch bridges, but its dynamics is still not well understood. In this paper, the out-of-plane dynamic behavior of a cable-arch structure is investigated. The equations governing the out-of-plane free vibration of the structure are derived using d'Alembert's principle. A transfer matrix method is used to solve the governing equations and determine the frequencies of the out-of-plane vibration. The theories are then used to study two specific cases: free vibration of a model cable-arch and simulation of an arch erection process. The effects of some key parameters of cable and arch, such as tension of cable and radius, open-angle and shape of arch, are examined. The results indicate that in-plane and spatial cables can largely improve the out-of-plane dynamic behavior of arch structures, which are further verified by analyzing the out-of-plane buckling of cable-arch structures. The present work should be valuable and significant not only for the fundamental research but also engineering design of roofs and bridges.

  8. A FUNDAMENTAL PLANE OF SPIRAL STRUCTURE IN DISK GALAXIES

    SciTech Connect

    Davis, Benjamin L.; Kennefick, Daniel; Kennefick, Julia; Shields, Douglas W.; Flatman, Russell; Hartley, Matthew T.; Berrier, Joel C.; Martinsson, Thomas P. K.; Swaters, Rob A.

    2015-03-20

    Spiral structure is the most distinctive feature of disk galaxies and yet debate persists about which theory of spiral structure is correct. Many versions of the density wave theory demand that the pitch angle be uniquely determined by the distribution of mass in the bulge and disk of the galaxy. We present evidence that the tangent of the pitch angle of logarithmic spiral arms in disk galaxies correlates strongly with the density of neutral atomic hydrogen in the disk and with the central stellar bulge mass of the galaxy. These three quantities, when plotted against each other, form a planar relationship that we argue should be fundamental to our understanding of spiral structure in disk galaxies. We further argue that any successful theory of spiral structure must be able to explain this relationship.

  9. Out-of-plane structural flexibility of phosphorene

    NASA Astrophysics Data System (ADS)

    Wang, Gaoxue; Loh, G. C.; Pandey, Ravindra; Karna, Shashi P.

    2016-02-01

    Phosphorene has been rediscovered recently, establishing itself as one of the most promising two-dimensional group-V elemental monolayers with direct band gap, high carrier mobility, and anisotropic electronic properties. In this paper, surface buckling and its effect on its electronic properties are investigated by using molecular dynamics simulations together with density functional theory calculations. We find that phosphorene shows superior structural flexibility along the armchair direction allowing it to have large curvatures. The semiconducting and direct band gap nature are retained with buckling along the armchair direction; the band gap decreases and transforms to an indirect band gap with buckling along the zigzag direction. The structural flexibility and electronic robustness along the armchair direction facilitate the fabrication of devices with complex shapes, such as folded phosphorene and phosphorene nano-scrolls, thereby offering new possibilities for the application of phosphorene in flexible electronics and optoelectronics.

  10. Out-of-plane structural flexibility of phosphorene.

    PubMed

    Wang, Gaoxue; Loh, G C; Pandey, Ravindra; Karna, Shashi P

    2016-02-01

    Phosphorene has been rediscovered recently, establishing itself as one of the most promising two-dimensional group-V elemental monolayers with direct band gap, high carrier mobility, and anisotropic electronic properties. In this paper, surface buckling and its effect on its electronic properties are investigated by using molecular dynamics simulations together with density functional theory calculations. We find that phosphorene shows superior structural flexibility along the armchair direction allowing it to have large curvatures. The semiconducting and direct band gap nature are retained with buckling along the armchair direction; the band gap decreases and transforms to an indirect band gap with buckling along the zigzag direction. The structural flexibility and electronic robustness along the armchair direction facilitate the fabrication of devices with complex shapes, such as folded phosphorene and phosphorene nano-scrolls, thereby offering new possibilities for the application of phosphorene in flexible electronics and optoelectronics.

  11. Morphological, structural and electrical investigations on non-polar a-plane ZnO epilayers

    NASA Astrophysics Data System (ADS)

    Lautenschlaeger, Stefan; Eisermann, Sebastian; Hofmann, Michael N.; Roemer, Udo; Pinnisch, Melanie; Laufer, Andreas; Meyer, Bruno K.; von Wenckstern, Holger; Lajn, Alexander; Schmidt, Florian; Grundmann, Marius; Blaesing, Juergen; Krost, Alois

    2010-07-01

    We report on the growth of non-polar a-plane ZnO by CVD on r-plane-sapphire-wafers, a-plane GaN-templates and a-plane ZnO single-crystal substrates. Only the homoepitaxial growth approach leads to a Frank-van-der-Merwe growth mode, as shown by atomic force microscopy. The X-ray-diffraction spectra of the homoepitaxial thin films mirror the excellent crystalline quality of the ZnO substrate. The morphological and the structural quality of the homoepitaxial films is comparable to the best results for the growth on c-plane ZnO-substrates. The impurity incorporation, especially of group III elements, seems to be reduced when growing on the non-polar a-plane surface compared to the c-plane films as demonstrated by secondary ion mass spectrometry (SIMS). Optical properties have been investigated using low temperature photoluminescence measurements. We employed capacitance-voltage measurements ( C- V) to measure the background carrier density and its profile from substrate/film interface throughout the film to the surface. In thermal admittance spectroscopy (TAS) specific traps could be distinguished, and their thermal activation energies and capture cross sections could be determined.

  12. Growth of InxGa1-xN/GaN QW structures with high indium concentration on c-plane and m-plane surfaces by MOVPE

    NASA Astrophysics Data System (ADS)

    Jönen, H.; Rossow, U.; Langer, T.; Dräger, A.; Hoffmann, L.; Bremers, H.; Hangleiter, A.; Bertram, F.; Metzner, S.; Christen, J.

    2008-11-01

    GaN/GaN quantum well (QW) structures grown on c-plane and m-plane surfaces have been investigated intended for long wavelength light emitters. On c-plane GaN QWs reached indium concentrations of xIn⩾35% with good optical and structural quality. For QW thicknesses dQW⩽2 nm a fully strained layer structure is observed and the indium concentration is quite homogenous. Under the same growth conditions of the QW region we find similar or even slightly larger indium concentrations on m-plane surfaces. QWs of such high indium concentrations, however, are very sensitive to the growth conditions of the subsequent layers and we observe degradation such as indium outdiffusion or partial relaxation for high growth temperatures.

  13. Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair

    PubMed Central

    Islam, Anowarul; Bohl, Michael S.; Tsai, Andrew G; Younesi, Mousa; Gillespie, Robert; Akkus, Ozan

    2015-01-01

    Background Currently, there are no well-established suture protocols to attach fully load-bearing scaffolds which span tendon defects between bone and muscle for repair of critical sized tendon tears. Methods to attach load-bearing tissue repair scaffolds could enable functional repair of tendon injuries. Methods Sixteen rabbit shoulders were dissected (New Zealand white rabbits, 1 yr. old, female) to isolate the humeral-infraspinatus muscle complex. A unique suture technique was developed to allow for a 5 mm segmental defect in infraspinatus tendon to be replaced with a mechanically strong bioscaffold woven from pure collagen threads. The suturing pattern resulted in a fully load-bearing scaffold. The tensile stiffness and strength of scaffold repair was compared with intact infraspinatus and regular direct repair. Findings The failure load and displacement at failure of the scaffold repair group were 59.9 N (Standard Deviation, SD = 10.7) and 10.3 mm (SD = 2.9), respectively and matched those obtained by direct repair group which were 57.5 N (SD = 15.3) and 8.6 mm (SD = 1.5), (p > 0.05). Failure load, displacement at failure and stiffness of both of the repair groups were half of the intact infraspinatus shoulder group. Interpretation With the developed suture technique, scaffolds repair showed similar failure load, displacement at failure and stiffness to the direct repair. This novel suturing pattern and the mechanical robustness of the scaffold at time zero indicates that the proposed model is mechanically viable for future in vivo studies which has a higher potential to translate into clinical uses. PMID:26009492

  14. Measurement of Three-Dimensional Flame Structure by Simultaneous Dual-plane CH PLIF, Single-plane OH PLIF and Stereoscopic PIV

    NASA Astrophysics Data System (ADS)

    Ueda, Takashi; Shimura, Masayasu; Choi, Gyung-Min; Tanahashi, Mamoru; Miyauchi, Toshio

    2008-11-01

    To investigate three-dimensional flame structures of turbulent premixed flame, dual-plane planar laser induced fluorescence (PLIF) of CH radical has been developed. The newly-developed dual-plane CH PLIF is combined with single-plane OH PLIF and stereoscopic particle image velocimetry (SPIV) to clarify the relation between flame geometry and turbulence characteristics. The laser sheets for OH PLIF and SPIV measurement are located at the center of two planes for CH PLIF. The separation between these two CH PLIF planes is selected to 500μm. The measurement was conducted in relatively high Reynolds number methane-air turbulent jet premixed flame. The experimental results show that various three-dimensional flame structures such as the handgrip structure, which has been shown by DNS, are included in high Reynolds number turbulent premixed flame. It was shown that the simultaneous measurement containing newly-developed dual- plane CH PLIF is useful for investigating the three-dimensional flame structure.

  15. Effect of fiber crosslinking on collagen-fiber reinforced collagen-chondroitin-6-sulfate materials for regenerating load-bearing soft tissues.

    PubMed

    Shepherd, J H; Ghose, S; Kew, S J; Moavenian, A; Best, S M; Cameron, R E

    2013-01-01

    Porous collagen-glycosaminoglycan structures are bioactive and exhibit a pore architecture favorable for both cellular infiltration and attachment; however, their inferior mechanical properties limit use, particularly in load-bearing situations. Reinforcement with collagen fibers may be a feasible route for enhancing the mechanical characteristics of these materials, providing potential for composites used for the repair and regeneration of soft tissue such as tendon, ligaments, and cartilage. Therefore, this study investigates the reinforcement of collagen-chondroitin-6-sulfate (C6S) porous structures with bundles of extruded, reconstituted type I collagen fibers. Fiber bundles were produced through extrusion and then, where applicable, crosslinked using a solution of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide. Fibers were then submerged in the collagen-C6S matrix slurry before being lyophilized. A second 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide crosslinking process was then applied to the composite material before a secondary lyophilization cycle. Where bundles had been previously crosslinked, composites withstood a load of approximately 60 N before failure, the reinforcing fibers remained dense and a favorable matrix pore structure resulted, with good interaction between fiber and matrix. Fibers that had not been crosslinked before lyophilization showed significant internal porosity and a channel existed between them and the matrix. Mechanical properties were significantly reduced, but the additional porosity could prove favorable for cell migration and has potential for directing aligned tissue growth.

  16. Influence of cyclic fatigue in water on the load-bearing capacity of dental bridges made of zirconia.

    PubMed

    Kohorst, Philipp; Dittmer, Marc Philipp; Borchers, Lothar; Stiesch-Scholz, Meike

    2008-09-01

    The humid atmosphere and permanent occurrence of chewing forces in the oral environment lead to degradation of ceramics used for prosthetic restorations. The aim of this in vitro study was to evaluate the influence of artificial aging on the load-bearing capacity of four-unit bridges, with both undamaged and predamaged zirconia frameworks. Additionally, different parameters for chewing simulation have been investigated and a finite element analysis was made to predict the location of highest tensile stresses within the bridges. A total of 60 frameworks were milled from presintered zirconia and divided into six homogeneous groups. Prior to veneering, frameworks of two groups were "damaged" by a defined saw cut similar to an accidental flaw generated during shape cutting. After veneering, FPDs were subjected to thermal and mechanical cycling - with the exception of control groups. The load-bearing capacity of tested FPDs was significantly reduced by artificial aging. In comparison to unaged specimens, fracture resistance decreased by about 40%, whereas preliminary damage did not have a significant effect. Increasing number of cycles and increasing upper load limit failed to show any additional effect on fracture force. To predict the progression of degradation under the terms of in vitro simulation for even longer periods, further aging experiments are required.

  17. Quad-plane stereoscopic PIV for fine-scale structure measurements in turbulence

    NASA Astrophysics Data System (ADS)

    Naka, Y.; Tomita, K.; Shimura, M.; Fukushima, N.; Tanahashi, M.; Miyauchi, T.

    2016-05-01

    The fine-scale structure in turbulence is investigated by quad-plane stereoscopic particle image velocimetry (QPSPIV). The quad-plane consists of two each of different polarizations and wavelengths, and it provides three velocity components at four independent parallel planes. Measurements have been undertaken in the developed region of a turbulent round jet with a spatial resolution sufficient to capture the small-scale structures. The advantage of the QPSPIV is presented in terms of the spectral response in the evaluation of the out-of-plane velocity gradient. The full velocity gradient tensor is computed with a fourth-order finite difference scheme in the out-of-plane direction as well as the in-plane directions. The turbulence quantities, such as the vorticity components, the energy dissipation rate and the second and third invariants of the velocity gradient tensor, are computed according to their faithful definitions. The coherent fine-scale eddies are extracted from the present QPSPIV data. The probability density functions of the diameter and the maximum azimuthal velocity of the extracted eddies exhibit their peak at approximately 8η and 1.5u_k, respectively, where η and u_k are the Kolmogorov length and velocity. These values agree well with the data in the literature. The phase-averaged distributions of turbulence quantities around the coherent fine-scale eddy indicate an apparent elliptic feature around the axis. Furthermore, the state of the strain rate exerting the eddy is quantified from the phase-averaged distributions of eigenvalues of the strain rate tensor and the alignment of the corresponding eigenvectors against the axis. The present study gives a solid experimental support of the coherent fine-scale structures in turbulence, and the technique can be applied to various flow fields and to the higher Reynolds number condition.

  18. Population analysis of plane-wave electronic structure calculations of bulk materials

    SciTech Connect

    Segall, M.D.; Shah, R.; Pickard, C.J.; Payne, M.C.

    1996-12-01

    {ital Ab} {ital initio} plane-wave electronic structure calculations are widely used in the study of bulk materials. A technique for the projection of plane-wave states onto a localized basis set is used to calculate atomic charges and bond populations by means of Mulliken analysis. We analyze a number of simple bulk crystals and find correlations of overlap population with covalency of bonding and bond strength, and effective valence charge with ionicity of bonding. Thus, we show that the techniques described in this paper may be usefully applied in the field of solid state physics. {copyright}{ital 1996 The American Physical Society.}

  19. PlaneWave Admittance Method- a novel approach for determining the electromagnetic modes in photonic structures.

    PubMed

    Dems, Maciej; Kotynski, Rafal; Panajotov, Krassimir

    2005-05-01

    In this article we present a novel approach for determining the electromagnetic modes of photonic multilayer structures. We combine the plane wave expansion method with the method of lines resulting in a fast and accurate computational technique which we named the plane wave admittance method. In addition, we incorporate perfectly matched layers at the boundaries parallel to the multilayer surfaces which allow for easy determination of leaky modes. The convergence of the method is verified for the case of photonic crystal slab showing very good agreement with the results obtained with full three-dimensional plane wave expansion method while the numerical effort is largely reduced. The numerical implementation of the method will be soon available on the web.

  20. Role of shear along horizontal plane in the formation of helicoidal structures

    NASA Astrophysics Data System (ADS)

    Koronovsky, N. V.; Gogonenkov, G. N.; Goncharov, M. A.; Timurziev, A. I.; Frolova, N. S.

    2009-09-01

    An unusual structural paragenesis, complicated by brachyanticlines, is revealed for the first time in the sedimentary cover of the West Siberian Plate by 3D seismic surveying. These are linear (in plan view) systems of en-echelon arranged low-amplitude normal faults related to wrench faults in the basement. On different sides off a wrench fault, the planes of normal faults dip in opposite directions, forming a helicoidal structure that resembles the blades of a propeller. In the section parallel to the wrench fault, the boundaries of the beds and normal fault planes dip in opposite directions as well. In the section across the strike of the normal faults converging toward the basement, the beds take the shape of an antiform with a crest sagged along the normal faults (flower structure). This structural assembly was formed as a result of interference of stress fields of horizontal shear in the vertical plane (induced by faulting in the basement) and in the horizontal plane (caused by gravity resistance of the cover). In this case, the displacements along the normal faults develop in both the vertical and, to a greater extent, horizontal directions, so that the faults in cover are actually characterized by normal-strike-slip kinematics. The regional N-S-trending compression of the West Siberian Plate is the main cause of shearing along the NW- and NE-trending faults in the basement, which make up a rhomb-shaped system in plan view. Petroliferous brachyanticlines, whose axes, notwithstanding tectonophysical laws, are oriented in the direction close to the maximum compression axis, are known in the large wrench fault zones of Western Siberia. Our experiments with equivalent materials showed that a local stress field arising at the ends of echeloned Riedel shears within a wrench fault zone may be a cause of the formation of such brachyanticlines. The progressive elongation of Riedel shears leads to the corresponding elongation of the brachyanticlines located between

  1. Performance of bioactive PMMA-based bone cement under load-bearing conditions: an in vivo evaluation and FE simulation.

    PubMed

    Fottner, Andreas; Nies, Berthold; Kitanovic, Denis; Steinbrück, Arnd; Mayer-Wagner, Susanne; Schröder, Christian; Heinemann, Sascha; Pohl, Ulrich; Jansson, Volkmar

    2016-09-01

    In the past, bioactive bone cement was investigated in order to improve the durability of cemented arthroplasties by strengthening the bone-cement interface. As direct bone-cement bonding may theoretically lead to higher stresses within the cement, the question arises, whether polymethylmethacrylate features suitable mechanical properties to withstand altered stress conditions? To answer this question, in vivo experiments and finite element simulations were conducted. Twelve rabbits were divided into two groups examining either bioactive polymethylmethacrylate-based cement with unchanged mechanical properties or commercially available polymethylmethacrylate cement. The cements were tested under load-bearing conditions over a period of 7 months, using a spacer prosthesis cemented into the femur. For the finite element analyses, boundary conditions of the rabbit femur were simulated and analyses were performed with respect to different loading scenarios. Calculations of equivalent stress distributions within the cements were applied, with a completely bonded cement surface for the bioactive cement and with a continuously interfering fibrous tissue layer for the reference cement. The bioactive cement revealed good in vivo bioactivity. In the bioactive cement group two failures (33 %), with complete break-out of the prosthesis occurred, while none in the reference group. Finite element analyses of simulated bioactive cement fixation showed an increase in maximal equivalent stress by 49.2 to 109.4 % compared to the simulation of reference cement. The two failures as well as an increase in calculated equivalent stress highlight the importance of fatigue properties of polymethylmethacrylate in general and especially when developing bioactive cements designated for load-bearing conditions. PMID:27530301

  2. Measurements of the streamwise vortical structures in a plane mixing layer

    NASA Technical Reports Server (NTRS)

    Bell, James H.; Mehta, Rabindra D.

    1992-01-01

    The 3D structure of a plane two-stream mixing layer of velocity ratio 0.6 and originating from laminar initial boundary layers was investigated through direct measurements made in a specially constructed mixing-layer wind tunnel. The main objective of the study was to establish quantitatively the presence and the role of the secondary streamwise vortex structure (of the kind that has been shown in past flow visualization investigations to ride among the primary spanwise vortices) in the development of a plane turbulent mixing layer at relatively high Reynolds numbers. Results indicate that the instability leading to the formation of streamwise vortices is initially amplified just downstream of the first spanwise roll-up. The streamwise vortices, which first appear in clusters containing vorticity of both signs, realign further downstream to form counterrotating pairs. Due to the amalgamation of like-sign vortices, the streamwise vortex spacing increases in a stepwise fashion.

  3. Photonic band structures solved by a plane-wave-based transfer-matrix method.

    PubMed

    Li, Zhi-Yuan; Lin, Lan-Lan

    2003-04-01

    Transfer-matrix methods adopting a plane-wave basis have been routinely used to calculate the scattering of electromagnetic waves by general multilayer gratings and photonic crystal slabs. In this paper we show that this technique, when combined with Bloch's theorem, can be extended to solve the photonic band structure for 2D and 3D photonic crystal structures. Three different eigensolution schemes to solve the traditional band diagrams along high-symmetry lines in the first Brillouin zone of the crystal are discussed. Optimal rules for the Fourier expansion over the dielectric function and electromagnetic fields with discontinuities occurring at the boundary of different material domains have been employed to accelerate the convergence of numerical computation. Application of this method to an important class of 3D layer-by-layer photonic crystals reveals the superior convergency of this different approach over the conventional plane-wave expansion method.

  4. Designing stable finite state machine behaviors using phase plane analysis and variable structure control

    SciTech Connect

    Feddema, J.T.; Robinett, R.D.; Driessen, B.J.

    1998-03-10

    This paper discusses how phase plane analysis can be used to describe the overall behavior of single and multiple autonomous robotic vehicles with finite state machine rules. The importance of this result is that one can begin to design provably asymptotically stable group behaviors from a set of simple control laws and appropriate switching points with decentralized variable structure control. The ability to prove asymptotically stable group behavior is especially important for applications such as locating military targets or land mines.

  5. A novel dual-frequency loading system for studying mechanobiology of load-bearing tissue.

    PubMed

    Zhang, Chunqiu; Qiu, Lulu; Gao, Lilan; Guan, Yinjie; Xu, Qiang; Zhang, Xizheng; Chen, Qian

    2016-12-01

    In mechanobiological research, an appropriate loading system is an essential tool to mimic mechanical signals in a native environment. To achieve this goal, we have developed a novel loading system capable of applying dual-frequency loading including both a low-frequency high-amplitude loading and a high-frequency low-amplitude loading, according to the mechanical conditions experienced by bone and articular cartilage tissues. The low-frequency high-amplitude loading embodies the main force from muscular contractions and/or reaction forces while the high-frequency low-amplitude loading represents an assistant force from small muscles, ligaments and/or other tissue in order to maintain body posture during human activities. Therefore, such dual frequency loading system may reflect the natural characteristics of complex mechanical load on bone or articular cartilage than the single frequency loading often applied during current mechanobiological experiments. The dual-frequency loading system is validated by experimental tests using precision miniature plane-mirror interferometers. The dual-frequency loading results in significantly more solute transport in articular cartilage than that of the low-frequency high-amplitude loading regiment alone, as determined by quantitative fluorescence microscopy of tracer distribution in articular cartilage. Thus, the loading system can provide a new method to mimic mechanical environment in bone and cartilage, thereby revealing the in vivo mechanisms of mechanosensation, mechanotransduction and mass-transport, and improving mechanical conditioning of cartilage and/or bone constructs for tissue engineering. PMID:27612712

  6. A novel dual-frequency loading system for studying mechanobiology of load-bearing tissue.

    PubMed

    Zhang, Chunqiu; Qiu, Lulu; Gao, Lilan; Guan, Yinjie; Xu, Qiang; Zhang, Xizheng; Chen, Qian

    2016-12-01

    In mechanobiological research, an appropriate loading system is an essential tool to mimic mechanical signals in a native environment. To achieve this goal, we have developed a novel loading system capable of applying dual-frequency loading including both a low-frequency high-amplitude loading and a high-frequency low-amplitude loading, according to the mechanical conditions experienced by bone and articular cartilage tissues. The low-frequency high-amplitude loading embodies the main force from muscular contractions and/or reaction forces while the high-frequency low-amplitude loading represents an assistant force from small muscles, ligaments and/or other tissue in order to maintain body posture during human activities. Therefore, such dual frequency loading system may reflect the natural characteristics of complex mechanical load on bone or articular cartilage than the single frequency loading often applied during current mechanobiological experiments. The dual-frequency loading system is validated by experimental tests using precision miniature plane-mirror interferometers. The dual-frequency loading results in significantly more solute transport in articular cartilage than that of the low-frequency high-amplitude loading regiment alone, as determined by quantitative fluorescence microscopy of tracer distribution in articular cartilage. Thus, the loading system can provide a new method to mimic mechanical environment in bone and cartilage, thereby revealing the in vivo mechanisms of mechanosensation, mechanotransduction and mass-transport, and improving mechanical conditioning of cartilage and/or bone constructs for tissue engineering.

  7. Crystallographic tilt and in-plane anisotropies of an a-plane InGaN/GaN layered structure grown by MOCVD on r-plane sapphire using a ZnO buffer

    NASA Astrophysics Data System (ADS)

    Liu, H. F.; Liu, W.; Guo, S.; Chi, D. Z.

    2016-03-01

    High-resolution x-ray diffraction (HRXRD) was used to investigate the crystallographic tilts and structural anisotropies in epitaxial nonpolar a-plane InGaN/GaN grown by metal-organic chemical vapor deposition on r-plane sapphire using a ZnO buffer. The substrate had an unintentional miscut of 0.14° towards its [-4 2 2 3] axis. However, HRXRD revealed a tilt of 0.26° (0.20°) between the ZnO (GaN) (11-20) and the Al2O3 (1-102) atomic planes, with the (11-20) axis of ZnO (GaN) tilted towards its c-axis, which has a difference of 163° in azimuth from that of the substrate’s miscut. Excess broadenings in the GaN/ZnO (11-20) rocking curves (RCs) were observed along its c-axis. Specific analyses revealed that partial dislocations and anisotropic in-plane strains, rather than surface-related effects, wafer curvature or stacking faults, are the dominant factors for the structural anisotropy. The orientation of the partial dislocations is most likely affected by the miscut of the substrate, e.g. via tilting of the misfit dislocation gliding planes created during island coalescences. Their Burgers vector components in the growth direction, in turn, gave rise to crystallographic tilts in the same direction as that of the excess RC-broadenings.

  8. Anti-plane transverse waves propagation in nanoscale periodic layered piezoelectric structures.

    PubMed

    Chen, A-Li; Yan, Dong-Jia; Wang, Yue-Sheng; Zhang, Chuanzeng

    2016-02-01

    In this paper, anti-plane transverse wave propagation in nanoscale periodic layered piezoelectric structures is studied. The localization factor is introduced to characterize the wave propagation behavior. The transfer matrix method based on the nonlocal piezoelectricity continuum theory is used to calculate the localization factor. Additionally, the stiffness matrix method is applied to compute the wave transmission spectra. A cut-off frequency is found, beyond which the elastic waves cannot propagate through the periodic structure. The size effect or the influence of the ratio of the internal to external characteristic lengths on the cut-off frequency and the wave propagation behavior are investigated and discussed. PMID:26518526

  9. A full 3D plane-wave-expansion model for 1-3 piezoelectric composite structures.

    PubMed

    Wilm, Mikaël; Ballandras, Sylvain; Laude, Vincent; Pastureaud, Thomas

    2002-09-01

    The plane-wave-expansion (PWE) approach dedicated to the simulation of periodic devices has been extended to 1-3 connectivity piezoelectric composite structures. The case of simple but actual piezoelectric composite structures is addressed, taking piezoelectricity, acoustic losses, and electrical excitation conditions rigorously into account. The material distribution is represented by using a bidimensional Fourier series and the electromechanical response is simulated using a Bloch-Floquet expansion together with the Fahmy-Adler formulation of the Christoffel problem. Application of the model to 1-3 connectivity piezoelectric composites is reported and compared to previously published analyses of this problem.

  10. Anti-plane transverse waves propagation in nanoscale periodic layered piezoelectric structures.

    PubMed

    Chen, A-Li; Yan, Dong-Jia; Wang, Yue-Sheng; Zhang, Chuanzeng

    2016-02-01

    In this paper, anti-plane transverse wave propagation in nanoscale periodic layered piezoelectric structures is studied. The localization factor is introduced to characterize the wave propagation behavior. The transfer matrix method based on the nonlocal piezoelectricity continuum theory is used to calculate the localization factor. Additionally, the stiffness matrix method is applied to compute the wave transmission spectra. A cut-off frequency is found, beyond which the elastic waves cannot propagate through the periodic structure. The size effect or the influence of the ratio of the internal to external characteristic lengths on the cut-off frequency and the wave propagation behavior are investigated and discussed.

  11. Structural anisotropic properties of a-plane GaN epilayers grown on r-plane sapphire by molecular beam epitaxy

    SciTech Connect

    Lotsari, A.; Kehagias, Th.; Katsikini, M.; Arvanitidis, J.; Ves, S.; Komninou, Ph.; Dimitrakopulos, G. P.; Tsiakatouras, G.; Tsagaraki, K.; Georgakilas, A.; Christofilos, D.

    2014-06-07

    Heteroepitaxial non-polar III-Nitride layers may exhibit extensive anisotropy in the surface morphology and the epilayer microstructure along distinct in-plane directions. The structural anisotropy, evidenced by the “M”-shape dependence of the (112{sup ¯}0) x-ray rocking curve widths on the beam azimuth angle, was studied by combining transmission electron microscopy observations, Raman spectroscopy, high resolution x-ray diffraction, and atomic force microscopy in a-plane GaN epilayers grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). The structural anisotropic behavior was attributed quantitatively to the high dislocation densities, particularly the Frank-Shockley partial dislocations that delimit the I{sub 1} intrinsic basal stacking faults, and to the concomitant plastic strain relaxation. On the other hand, isotropic samples exhibited lower dislocation densities and a biaxial residual stress state. For PAMBE growth, the anisotropy was correlated to N-rich (or Ga-poor) conditions on the surface during growth, that result in formation of asymmetric a-plane GaN grains elongated along the c-axis. Such conditions enhance the anisotropy of gallium diffusion on the surface and reduce the GaN nucleation rate.

  12. Chiral nematic self-assembly of minimally surface damaged chitin nanofibrils and its load bearing functions

    NASA Astrophysics Data System (ADS)

    Oh, Dongyeop X.; Cha, Yun Jeong; Nguyen, Hoang-Linh; Je, Hwa Heon; Jho, Yong Seok; Hwang, Dong Soo; Yoon, Dong Ki

    2016-03-01

    Chitin is one of the most abundant biomaterials in nature, with 1010 tons produced annually as hierarchically organized nanofibril fillers to reinforce the exoskeletons of arthropods. This green and cheap biomaterial has attracted great attention due to its potential application to reinforce biomedical materials. Despite that, its practical use is limited since the extraction of chitin nanofibrils requires surface modification involving harsh chemical treatments, leading to difficulties in reproducing their natural prototypal hierarchical structure, i.e. chiral nematic phase. Here, we develop a chemical etching-free approach using calcium ions, called “natural way”, to disintegrate the chitin nanofibrils while keeping the essential moiety for the self-assembly, ultimately resulting in the reproduction of chitin’s natural chiral structure in a polymeric matrix. This chiral chitin nanostructure exceptionally toughens the composite. Our resultant chiral nematic phase of chitin materials can contribute to the understanding and use of the reinforcing strategy in nature.

  13. Chiral nematic self-assembly of minimally surface damaged chitin nanofibrils and its load bearing functions

    PubMed Central

    Oh, Dongyeop X.; Cha, Yun Jeong; Nguyen, Hoang-Linh; Je, Hwa Heon; Jho, Yong Seok; Hwang, Dong Soo; Yoon, Dong Ki

    2016-01-01

    Chitin is one of the most abundant biomaterials in nature, with 1010 tons produced annually as hierarchically organized nanofibril fillers to reinforce the exoskeletons of arthropods. This green and cheap biomaterial has attracted great attention due to its potential application to reinforce biomedical materials. Despite that, its practical use is limited since the extraction of chitin nanofibrils requires surface modification involving harsh chemical treatments, leading to difficulties in reproducing their natural prototypal hierarchical structure, i.e. chiral nematic phase. Here, we develop a chemical etching-free approach using calcium ions, called “natural way”, to disintegrate the chitin nanofibrils while keeping the essential moiety for the self-assembly, ultimately resulting in the reproduction of chitin’s natural chiral structure in a polymeric matrix. This chiral chitin nanostructure exceptionally toughens the composite. Our resultant chiral nematic phase of chitin materials can contribute to the understanding and use of the reinforcing strategy in nature. PMID:26988392

  14. A novel H-plane filter using double-layer substrate integrated waveguide with defected ground structures

    NASA Astrophysics Data System (ADS)

    Aghayari, Hassan; Komjani, Nader; Molaei Garmjani, Nima

    2013-06-01

    The novel double layer substrate integrated waveguide (SIW) technology is used for realisation of conventional H-plane filter, which is manufactured in waveguide. This proposed filter is totally realised in double layer dielectric substrate with metallic vias and fabricated using a standard printed circuit board (PCB) process. In previous studies, prototypes of E-plane and H-plane filter were designed and fabricated in standard waveguides. The H-plane type of those two has the same frequency response as that of the E-plane type, while its cross section is one-quarter. Similarly, the SIW H-plane filter, which is presented in this article, has the same dispersion characteristics as that of waveguide filter while its dimensions are very shorter. Moreover, by using a sandwich model of double layer SIW, the interleaved metal vane is fabricated between two substrates easily. We can also improve the frequency response of the SIW H-plane filter using defected ground structure (DGS). Therefore, in DGS SIW H-plane filter, which is presented, the return loss and insertion loss in passband are less than conventional H-plane filter. The improvement of the spurious response is the other trait of DGS SIW H-plane filter.

  15. Engineering of optical polarization based on electronic band structures of A-plane ZnO layers under biaxial strains

    SciTech Connect

    Matsui, Hiroaki Tabata, Hitoshi; Hasuike, Noriyuki; Harima, Hiroshi

    2014-09-21

    In-plane anisotropic strains in A-plane layers on the electronic band structure of ZnO were investigated from the viewpoint of optical polarization anisotropy. Investigations utilizing k·p perturbation theory revealed that energy transitions and associated oscillation strengths were dependent on in-plane strains. The theoretical correlation between optical polarizations and in-plane strains was experimentally demonstrated using A-plane ZnO layers with different in-plane strains. Finally, optical polarization anisotropy and its implications for in-plane optical properties are discussed in relation to the energy shift between two orthogonal directions. Higher polarization rotations were obtained in an A-plane ZnO layer with in-plane biaxially compressive strains as compared to strain-free ZnO. This study provides detailed information concerning the role played by in-plane strains in optically polarized applications based on nonpolar ZnO in the ultra-violet region.

  16. Controlling the Electronic Structures and Properties of in-Plane Transition-Metal Dichalcogenides Quantum Wells

    PubMed Central

    Wei, Wei; Dai, Ying; Niu, Chengwang; Huang, Baibiao

    2015-01-01

    In-plane transition-metal dichalcogenides (TMDs) quantum wells have been studied on the basis of first-principles density functional calculations to reveal how to control the electronic structures and the properties. In collection of quantum confinement, strain and intrinsic electric field, TMD quantum wells offer a diverse of exciting new physics. The band gap can be continuously reduced ascribed to the potential drop over the embedded TMD and the strain substantially affects the band gap nature. The true type-II alignment forms due to the coherent lattice and strong interface coupling suggesting the effective separation and collection of excitons. Interestingly, two-dimensional quantum wells of in-plane TMD can enrich the photoluminescence properties of TMD materials. The intrinsic electric polarization enhances the spin-orbital coupling and demonstrates the possibility to achieve topological insulator state and valleytronics in TMD quantum wells. In-plane TMD quantum wells have opened up new possibilities of applications in next-generation devices at nanoscale. PMID:26616013

  17. Structural Anisotropy and Optical Properties of Nonpolar a-Plane GaN Epitaxial Layers.

    PubMed

    Seo, Yong Gon; Shin, Sun Hye; Kim, Doo Soo; Yoon, Hyung-Do; Hwang, Sung-Min; Baik, Kwang Hyeon

    2015-10-01

    In-plane structural anisotropy is characteristic of nonpolar (1120) a-plane GaN (a-GaN) films grown on r-plane sapphire substrates. The anisotropic peak broadenings of X-ray rocking curves (XRCs) are clearly observed with M- or W-shaped dependence on the azimuth angles. We investigated the optical properties of both M- and W-shaped a-GaN samples with room and low-temperature photoluminescence (PL) measurements. The W-shaped a-GaN film showed higher PL intensity and more compressive strain compared to the M-shaped a-GaN film, whereas the XRC peak widths of the M-shaped a-GaN film on the azimuth angles are lower than those of W-shaped specimens, indicating that better crystalline quality was obtained. We speculate that the PL intensity and strain state of a-GaN layers may be more influenced by the crystallinity of a specific crystal orientation or direction, especially along the m-axis as opposed to the c-axis. This occurrence is most likely due to anisotropic defect distributions, resulting from differences in dangling bond densities of (0001) and {1-100} facets.

  18. Role of isostaticity and load-bearing microstructure in the elasticity of yielded colloidal gels.

    PubMed

    Hsiao, Lilian C; Newman, Richmond S; Glotzer, Sharon C; Solomon, Michael J

    2012-10-01

    We report a simple correlation between microstructure and strain-dependent elasticity in colloidal gels by visualizing the evolution of cluster structure in high strain-rate flows. We control the initial gel microstructure by inducing different levels of isotropic depletion attraction between particles suspended in refractive index matched solvents. Contrary to previous ideas from mode coupling and micromechanical treatments, our studies show that bond breakage occurs mainly due to the erosion of rigid clusters that persist far beyond the yield strain. This rigidity contributes to gel elasticity even when the sample is fully fluidized; the origin of the elasticity is the slow Brownian relaxation of rigid, hydrodynamically interacting clusters. We find a power-law scaling of the elastic modulus with the stress-bearing volume fraction that is valid over a range of volume fractions and gelation conditions. These results provide a conceptual framework to quantitatively connect the flow-induced microstructure of soft materials to their nonlinear rheology.

  19. Complex band structure under plane-wave nonlocal pseudopotential Hamiltonian of metallic wires and electrodes

    SciTech Connect

    Yang, Chao

    2009-07-17

    We present a practical approach to calculate the complex band structure of an electrode for quantum transport calculations. This method is designed for plane wave based Hamiltonian with nonlocal pseudopotentials and the auxiliary periodic boundary condition transport calculation approach. Currently there is no direct method to calculate all the evanescent states for a given energy for systems with nonlocal pseudopotentials. On the other hand, in the auxiliary periodic boundary condition transport calculation, there is no need for all the evanescent states at a given energy. The current method fills this niche. The method has been used to study copper and gold nanowires and bulk electrodes.

  20. Anodized titania: Processing and characterization to improve cell-materials interactions for load bearing implants

    NASA Astrophysics Data System (ADS)

    Das, Kakoli

    The objective of this study is to investigate in vitro cell-materials interactions using human osteoblast cells on anodized titanium. Titanium is a bioinert material and, therefore, gets encapsulated after implantation into the living body by a fibrous tissue that isolates them from the surrounding tissues. In this work, bioactive nonporous and nanoporous TiO2 layers were grown on commercially pure titanium substrate by anodization process using different electrolyte solutions namely (1) H3PO 4, (2) HF and (3) H2SO4, (4) aqueous solution of citric acid, sodium fluoride and sulfuric acid. The first three electrolytes produced bioactive TiO2 films with a nonporous structure showing three distinctive surface morphologies. Nanoporous morphology was obtained on Ti-surfaces from the fourth electrolyte at 20V for 4h. Cross-sectional view of the nanoporous surface reveals titania nanotubes of length 600 nm. It was found that increasing anodization time initially increased the height of the nanotubes while maintaining the tubular array structure, but beyond 4h, growth of nanotubes decreased with a collapsed array structure. Human osteoblast (HOB) cell attachment and growth behavior were studied using an osteoprecursor cell line (OPC 1) for 3, 7 and 11 days. Colonization of the cells was noticed with distinctive cell-to-cell attachment on HF anodized surfaces. TiO2 layer grown in H2SO4 electrolyte did not show significant cell growth on the surface, and some cell death was also noticed. Good cellular adherence with extracellular matrix extensions in between the cells was noticed for samples anodized with H3PO 4 electrolyte and nanotube surface. Cell proliferation was excellent on anodized nanotube surfaces. An abundant amount of extracellular matrix (ECM) between the neighboring cells was also noticed on nanotube surfaces with filopodia extensions coming out from cells to grasp the nanoporous surface for anchorage. To better understand and compare cell-materials interactions

  1. Three-dimensional vortical structures of transition in plane channel flow

    NASA Technical Reports Server (NTRS)

    Biringen, S.

    1987-01-01

    Three-dimensional visualization of flwo field structures in transitional plane channel flow obtained from a numerical simulation are presented at two Reynolds numbers. It is revealed that at the one-spike stage, independent of Reynolds number, the flow is characterized by a multi-layer vortex system. In the upper layer, total vorticity vector plots indicate a high-shear layer dominated by spanwise vorticity, whereas the middle layer (corresponding approximately to the critical layer) forms a vortex loop (alpha-vortex) consisting of strong streamwise and spanwise vorticity components. At the three-spike stage, the breakdown of the vortical structure proceeds in a manner similar to frontal relaminarization of turbulent spots. This process is accompanied by intense vortex lift-up activity near the wall which seems to originate at the legs of the vortex loop trailing the high-shear layer. Finally, at the five-spike stage, it is shown that high-vorticity regions (vortical structures) develop into horseshow eddies in planes inclined to the main flow direction.

  2. Static load bearing exercises of individuals with transfemoral amputation fitted with an osseointegrated implant: reliability of kinetic data.

    PubMed

    Vertriest, Sofie; Coorevits, Pascal; Hagberg, Kerstin; Brånemark, Rickard; Häggström, Eva; Vanderstraeten, Guy; Frossard, Laurent

    2015-05-01

    This study aimed at presenting the intra-tester reliability of the static load bearing exercises (LBEs) performed by individuals with transfemoral amputation (TFA) fitted with an osseointegrated implant to stimulate the bone remodeling process. There is a need for a better understanding of the implementation of these exercises particularly the reliability. The intra-tester reliability is discussed with a particular emphasis on inter-load prescribed, inter-axis and inter-component reliabilities as well as the effect of body weight normalization. Eleven unilateral TFAs fitted with an OPRA implant performed five trials in four loading conditions. The forces and moments on the three axes of the implant were measured directly with an instrumented pylon including a six-channel transducer. Reliability of loading variables was assessed using intraclass correlation coefficients (ICCs) and percentage standard error of measurement values ( %SEMs ). The ICCs of all variables were above 0.9 and the %SEM values ranged between 0 and 87%. This study showed a high between-participants' variance highlighting the lack of loading consistency typical of symptomatic population as well as a high reliability between the loading sessions indicating a plausible correct repetition of the LBE by the participants. However, these outcomes must be understood within the framework of the proposed experimental protocol.

  3. Fabrication of a biodegradable calcium polyphosphate/polyvinyl-urethane carbonate composite for high load bearing osteosynthesis applications.

    PubMed

    Ramsay, Scott D; Pilliar, Robert M; Santerre, J Paul

    2010-07-01

    The formation of biodegradable implants for use in osteosynthesis has been a major goal of biomaterials research for the past 2-3 decades. Self-reinforced polylactide systems represent the most significant success of this research to date, however, with elastic constants up to 12-15 GPa at best, they fail to provide the initial stiffness required of devices for stabilizing fractures of major load-bearing bones. Our research has investigated the use of calcium polyphosphate (CPP), an inorganic polymer in combination with polyvinyl-urethane carbonate (PVUC) organic polymers for such applications. Initial studies indicated that composite samples formed as interpenetrating phase composites (IPC) exhibited suitable as-made strength and stiffness, however, they displayed a rapid loss of properties when exposed to in vitro aging. An investigation to determine the mechanism of this accelerated in vitro degradation for the IPCs as well as to identify possible design changes to overcome this drawback was undertaken using a model IPC system. It was found that strong interfacial strength and minimal swelling of the PVUC are very important for obtaining and maintaining appropriate mechanical properties in vitro.

  4. Fabrication of a biodegradable calcium polyphosphate/polyvinyl-urethane carbonate composite for high load bearing osteosynthesis applications.

    PubMed

    Ramsay, Scott D; Pilliar, Robert M; Santerre, J Paul

    2010-07-01

    The formation of biodegradable implants for use in osteosynthesis has been a major goal of biomaterials research for the past 2-3 decades. Self-reinforced polylactide systems represent the most significant success of this research to date, however, with elastic constants up to 12-15 GPa at best, they fail to provide the initial stiffness required of devices for stabilizing fractures of major load-bearing bones. Our research has investigated the use of calcium polyphosphate (CPP), an inorganic polymer in combination with polyvinyl-urethane carbonate (PVUC) organic polymers for such applications. Initial studies indicated that composite samples formed as interpenetrating phase composites (IPC) exhibited suitable as-made strength and stiffness, however, they displayed a rapid loss of properties when exposed to in vitro aging. An investigation to determine the mechanism of this accelerated in vitro degradation for the IPCs as well as to identify possible design changes to overcome this drawback was undertaken using a model IPC system. It was found that strong interfacial strength and minimal swelling of the PVUC are very important for obtaining and maintaining appropriate mechanical properties in vitro. PMID:20524193

  5. The Behavior of Water in Collagen and Hydroxyapatite Sites of Cortical Bone: Fracture, Mechanical Wear, and Load Bearing Studies

    PubMed Central

    Gul-E-Noor, Farhana; Singh, Chandan; Papaioannou, Antonios; Sinha, Neeraj; Boutis, Gregory S.

    2015-01-01

    The mechanical properties of cortical bone, which is largely comprised of collagen, hydroxyapatite, and water, are known to hinge on hydration. Recently, the characteristics of water in bone have drawn attention as potential markers of bone quality. We report on the dynamics, diffusion, population, and exchange of water in cortical bone by NMR relaxation and diffusion methodologies. Relaxation measurements over timescales ranging from 0.001 to 4.2 s reveal two distinguishable water environments. Systematic exposure to ethylenediaminetetraacetic acid or collagenase reveals one peak in our 2D relaxation map belonging to water present in the hydroxyapatite rich environment, and a second peak with shorter relaxation times arising from a collagen rich site. Diffusion-T2 measurements allowed for direct measurement of the diffusion coefficient of water in all observable reservoirs. Further, deuterium relaxation methods were applied to study cortical bone under an applied force, following mechanical wear or fracture. The tumbling correlation times of water reduce in all three cases, indicating that water dynamics may be used as a probe of bone quality. Lastly, changes in the relative populations and correlation times of water in bone under an applied force suggest that load bearing occurs largely in the collagen rich environment and is reversible. PMID:26659838

  6. A tissue engineering solution for segmental defect regeneration in load-bearing long bones.

    PubMed

    Reichert, Johannes C; Cipitria, Amaia; Epari, Devakara R; Saifzadeh, Siamak; Krishnakanth, Pushpanjali; Berner, Arne; Woodruff, Maria A; Schell, Hanna; Mehta, Manav; Schuetz, Michael A; Duda, Georg N; Hutmacher, Dietmar W

    2012-07-01

    The reconstruction of large defects (>10 mm) in humans usually relies on bone graft transplantation. Limiting factors include availability of graft material, comorbidity, and insufficient integration into the damaged bone. We compare the gold standard autograft with biodegradable composite scaffolds consisting of medical-grade polycaprolactone and tricalcium phosphate combined with autologous bone marrow-derived mesenchymal stem cells (MSCs) or recombinant human bone morphogenetic protein 7 (rhBMP-7). Critical-sized defects in sheep--a model closely resembling human bone formation and structure--were treated with autograft, rhBMP-7, or MSCs. Bridging was observed within 3 months for both the autograft and the rhBMP-7 treatment. After 12 months, biomechanical analysis and microcomputed tomography imaging showed significantly greater bone formation and superior strength for the biomaterial scaffolds loaded with rhBMP-7 compared to the autograft. Axial bone distribution was greater at the interfaces. With rhBMP-7, at 3 months, the radial bone distribution within the scaffolds was homogeneous. At 12 months, however, significantly more bone was found in the scaffold architecture, indicating bone remodeling. Scaffolds alone or with MSC inclusion did not induce levels of bone formation comparable to those of the autograft and rhBMP-7 groups. Applied clinically, this approach using rhBMP-7 could overcome autograft-associated limitations.

  7. Fabrication and characterization of interconnected porous biodegradable poly(ε-caprolactone) load bearing scaffolds.

    PubMed

    Allaf, Rula M; Rivero, Iris V

    2011-08-01

    In this study, poly(ε-caprolactone) (PCL)/poly(ethylene oxide) (PEO) (50:50 wt%) immiscible blend was used as a model system to investigate the feasibility of a novel solventless fabrication approach that combines cryomilling, compression molding and porogen leaching techniques to prepare interconnected porous scaffolds for tissue engineering. PCL was cryomilled with PEO to form blend powders. Compression molding was used to consolidate and anneal the cryomilled powders. Selective dissolution of the PEO with water resulted in interconnected porous scaffolds. Sodium chloride salt (NaCl) was subsequently added to cryomilled powder to increase the porosity of scaffolds. The prepared scaffolds had homogeneous pore structures, a porosity of ~50% which was increased by mixing salt with the blend (~70% for 60% wt% NaCl), and a compressive modulus and strength (ε = 10%) of 60 and 2.8 MPa, respectively. The results of the study confirm that this novel approach offers a viable alternative to fabricate scaffolds.

  8. Woven silk fabric-reinforced silk nanofibrous scaffolds for regenerating load-bearing soft tissues.

    PubMed

    Han, F; Liu, S; Liu, X; Pei, Y; Bai, S; Zhao, H; Lu, Q; Ma, F; Kaplan, D L; Zhu, H

    2014-02-01

    Although three-dimensional (3-D) porous regenerated silk scaffolds with outstanding biocompatibility, biodegradability and low inflammatory reactions have promising application in different tissue regeneration, the mechanical properties of regenerated scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This study presents woven silk fabric-reinforced silk nanofibrous scaffolds aimed at dermal tissue engineering. To improve the mechanical properties, silk scaffolds prepared by lyophilization were reinforced with degummed woven silk fabrics. The ultimate tensile strength, elongation at break and suture retention strength of the scaffolds were significantly improved, providing suitable mechanical properties strong enough for clinical applications. The stiffness and degradation behaviors were then further regulated by different after-treatment processes, making the scaffolds more suitable for dermal tissue regeneration. The in vitro cell culture results indicated that these scaffolds maintained their excellent biocompatibility after being reinforced with woven silk fabrics. Without sacrifice of porous structure and biocompatibility, the fabric-reinforced scaffolds with better mechanical properties could facilitate future clinical applications of silk as matrices in skin repair. PMID:24090985

  9. Electronic and crystal structure changes induced by in-plane oxygen vacancies in multiferroic YMnO3

    DOE PAGESBeta

    Cheng, Shaobo; Meng, Qingping; Li, Mengli; Duan, Wenhui; Zhao, Y. G.; Sun, X. F.; Zhu, Yimei; Zhu, Jing

    2016-02-08

    Here, the widely spread oxygen vacancies (VO) in multiferroic materials can strongly affect their physical properties. However, their exact influence has rarely been identified in hexagonal manganites. Here, with the combined use of transmission electron microscopy (TEM) and first-principles calculations, we have systematically studied the electronic and crystal structure modifications induced by VO located at the same Mn atomic plane (in-plane VO). Our TEM experiments reveal that the easily formed in-plane VO not only influence the electronic structure of YMnO3 but alter the in-plane Wyckoff positions of Mn ions, which may subsequently affect the intraplane and interplane exchange interaction ofmore » Mn ions. The ferroelectricity is also impaired due to the introduction of VO. Further calculations confirm these electronic and structural changes and modifications. Our results indicate that the electronic and crystal structure of YMnO3 can be manipulated by the creation of VO.« less

  10. Electronic and crystal structure changes induced by in-plane oxygen vacancies in multiferroic YMn O3

    NASA Astrophysics Data System (ADS)

    Cheng, Shaobo; Li, Menglei; Meng, Qingping; Duan, Wenhui; Zhao, Y. G.; Sun, X. F.; Zhu, Yimei; Zhu, Jing

    2016-02-01

    The widely spread oxygen vacancies (VO) in multiferroic materials can strongly affect their physical properties. However, their exact influence has rarely been identified in hexagonal manganites. Here, with the combined use of transmission electron microscopy (TEM) and first-principles calculations, we have systematically studied the electronic and crystal structure modifications induced by VO located at the same Mn atomic plane (in-plane VO). Our TEM experiments reveal that the easily formed in-plane VO not only influence the electronic structure of YMn O3 but alter the in-plane Wyckoff positions of Mn ions, which may subsequently affect the intraplane and interplane exchange interaction of Mn ions. The ferroelectricity is also impaired due to the introduction of VO. Further calculations confirm these electronic and structural changes and modifications. Our results indicate that the electronic and crystal structure of YMn O3 can be manipulated by the creation of VO.

  11. Simulated ΛCDM analogues of the thin plane of satellites around the Andromeda galaxy are not kinematically coherent structures

    NASA Astrophysics Data System (ADS)

    Buck, Tobias; Dutton, Aaron A.; Macciò, Andrea V.

    2016-08-01

    A large fraction of the dwarf satellites orbiting the Andromeda galaxy are surprisingly aligned in a thin, extended and apparently kinematically coherent planar structure. Such a structure is not easily found in simulations based on the cold dark matter model (ΛCDM). Using 21 high-resolution cosmological simulations, we analyse the kinematics of planes of satellites similar to the one around Andromeda. We find good agreement when co-rotation is characterized by the line-of-sight velocity. At the same time, when co-rotation is inferred by the angular momenta of the satellites, the planes are in agreement with the plane around our Galaxy. We find such planes to be common in our high-concentration haloes. The number of co-rotating satellites obtained from the sign of the line-of-sight velocity shows large variations depending on the viewing angle and is consistent with that obtained from a sample with random velocities. We find that the clustering of angular momentum vectors of the satellites in the plane is a better measure of the kinematic coherence. Thus we conclude that the line-of-sight velocity is not well suited as a proxy for the kinematical coherence of the plane. Analysis of the kinematics of our planes shows a fraction of ˜30 per cent chance-aligned satellites. Tracking the satellites in the plane back in time reveals that these planes are a transient feature and not kinematically coherent as would appear at first sight. Thus we expect some of the satellites in the plane around Andromeda to have high velocities perpendicular to the plane.

  12. Neutron scattering in the plane of membranes: structure of alamethicin pores.

    PubMed Central

    He, K; Ludtke, S J; Worcester, D L; Huang, H W

    1996-01-01

    A technique of neutron in-plane scattering for studying the structures of peptide pores in membranes is described. Alamethicin in the inserted state was prepared and undeuterated and deuterated dilauroyl phosphatidylcholine (DLPC) hydrated with D2O or H2O. Neutron in-plane scattering showed a strong dependence on deuteration, clearly indicating that water is a part of the high-order structure of inserted alamethicin. The data are consistent with the simple barrel-stave model originally proposed by Baumann and Mueller. The theoretical curves computed with this model at four different deuteration conditions agree with the data in all cases. Both the diameter of the water pore and the effective outside diameter of the channel are determined accurately. Alamethicin forms pores in a narrow range of size. In a given sample condition, > 70% of the peptide forms pores of n and n +/- 1 monomers. The pore size varies with hydration and with lipid. In DLPC, the pores are made of n = 8-9 monomers, with a water pore approximately 18 A in diameter and with an effective outside diameter of approximately 40 A. In diphytanoyl phosphatidylcholine, the pores are made of n approximately 11 monomers, with a water pore approximately 26 A in diameter, with an effective outside diameter of approximately 50 A. Images FIGURE 1 PMID:8744303

  13. Dense ionic fluids confined in planar capacitors: in- and out-of-plane structure from classical density functional theory.

    PubMed

    Härtel, Andreas; Samin, Sela; van Roij, René

    2016-06-22

    The ongoing scientific interest in the properties and structure of electric double layers (EDLs) stems from their pivotal role in (super)capacitive energy storage, energy harvesting, and water treatment technologies. Classical density functional theory (DFT) is a promising framework for the study of the in- and out-of-plane structural properties of double layers. Supported by molecular dynamics simulations, we demonstrate the adequate performance of DFT for analyzing charge layering in the EDL perpendicular to the electrodes. We discuss charge storage and capacitance of the EDL and the impact of screening due to dielectric solvents. We further calculate, for the first time, the in-plane structure of the EDL within the framework of DFT. While our out-of-plane results already hint at structural in-plane transitions inside the EDL, which have been observed recently in simulations and experiments, our DFT approach performs poorly in predicting in-plane structure in comparison to simulations. However, our findings isolate fundamental issues in the theoretical description of the EDL within the primitive model and point towards limitations in the performance of DFT in describing the out-of-plane structure of the EDL at high concentrations and potentials.

  14. Dense ionic fluids confined in planar capacitors: in- and out-of-plane structure from classical density functional theory.

    PubMed

    Härtel, Andreas; Samin, Sela; van Roij, René

    2016-06-22

    The ongoing scientific interest in the properties and structure of electric double layers (EDLs) stems from their pivotal role in (super)capacitive energy storage, energy harvesting, and water treatment technologies. Classical density functional theory (DFT) is a promising framework for the study of the in- and out-of-plane structural properties of double layers. Supported by molecular dynamics simulations, we demonstrate the adequate performance of DFT for analyzing charge layering in the EDL perpendicular to the electrodes. We discuss charge storage and capacitance of the EDL and the impact of screening due to dielectric solvents. We further calculate, for the first time, the in-plane structure of the EDL within the framework of DFT. While our out-of-plane results already hint at structural in-plane transitions inside the EDL, which have been observed recently in simulations and experiments, our DFT approach performs poorly in predicting in-plane structure in comparison to simulations. However, our findings isolate fundamental issues in the theoretical description of the EDL within the primitive model and point towards limitations in the performance of DFT in describing the out-of-plane structure of the EDL at high concentrations and potentials. PMID:27116552

  15. Dense ionic fluids confined in planar capacitors: in- and out-of-plane structure from classical density functional theory

    NASA Astrophysics Data System (ADS)

    Härtel, Andreas; Samin, Sela; van Roij, René

    2016-06-01

    The ongoing scientific interest in the properties and structure of electric double layers (EDLs) stems from their pivotal role in (super)capacitive energy storage, energy harvesting, and water treatment technologies. Classical density functional theory (DFT) is a promising framework for the study of the in- and out-of-plane structural properties of double layers. Supported by molecular dynamics simulations, we demonstrate the adequate performance of DFT for analyzing charge layering in the EDL perpendicular to the electrodes. We discuss charge storage and capacitance of the EDL and the impact of screening due to dielectric solvents. We further calculate, for the first time, the in-plane structure of the EDL within the framework of DFT. While our out-of-plane results already hint at structural in-plane transitions inside the EDL, which have been observed recently in simulations and experiments, our DFT approach performs poorly in predicting in-plane structure in comparison to simulations. However, our findings isolate fundamental issues in the theoretical description of the EDL within the primitive model and point towards limitations in the performance of DFT in describing the out-of-plane structure of the EDL at high concentrations and potentials.

  16. Cross-plane heat transfer through single-layer carbon structures.

    PubMed

    Zhang, Huaichen; Nedea, Silvia V; Rindt, Camilo C M; Smeulders, David M J

    2016-02-21

    Graphene-based nano-structures have been recently proposed to function as additives to improve the conductivity of thermally sluggish phase change materials (PCMs). Based on the existing research studies, the improvement is dependent not only on the matrix material, but also on the geometry of the carbon structure. To gain more insight into the nano-scale thermal transport problem, we launched the current pilot research using water as the matrix material, to represent the hydroxyl-group-rich sugar alcohols as PCMs. We have found that the heat conduction across a graphene layer to water is much faster than the heat conduction to the graphene layer itself. Also, the high graphene-water thermal contact resistance fails to acknowledge the fast thermal kinetics of the low frequency phonons. In the investigation of the geometry effect, the cross-plane heat transfer coefficient is found to decrease with decreasing CNT diameter except CNT(9,9). PMID:26818392

  17. Strained-layer superlattice focal plane array having a planar structure

    DOEpatents

    Kim, Jin K.; Carroll, Malcolm S.; Gin, Aaron; Marsh, Phillip F.; Young, Erik W.; Cich, Michael J.

    2010-07-13

    An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

  18. Dynamics of the spatial structure of pulsed discharges in dense gases in point cathode-plane anode gaps and their erosion effect on the plane electrode surface

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh.; Blinova, O. M.; Erofeev, M. V.; Karelin, V. I.; Ripenko, V. S.; Tarasenko, V. F.; Trenkin, A. A.; Shibitov, Yu. M.; Shulepov, M. A.

    2016-09-01

    The dynamics of the spatial structure of the plasma of pulsed discharges in air and nitrogen in a nonuniform electric field and their erosion effect on the plane anode surface were studied experimentally. It is established that, at a nanosecond front of the voltage pulse, a diffuse discharge forms in the point cathode-plane anode gap due to the ionization wave propagating from the cathode. As the gap length decreases, the diffuse discharge transforms into a spark. A bright spot on the anode appears during the diffuse discharge, while the spark channel forms in the later discharge stage. The microstructure of autographs of anode spots and spark channels in discharges with durations of several nanoseconds is revealed. The autographs consist of up to 100 and more microcraters 5-100 μm in diameter. It is shown that, due to the short duration of the voltage pulse, a diffuse discharge can be implemented, several pulses of which do not produce appreciable erosion on the plane anode or the soot coating deposited on it.

  19. Ability of zirconia double coated with titanium and hydroxyapatite to bond to bone under load-bearing conditions.

    PubMed

    Suzuki, Takashi; Fujibayashi, Shunsuke; Nakagawa, Yasuaki; Noda, Iwao; Nakamura, Takashi

    2006-03-01

    As a preclinical study, we evaluated the ability of hydroxyapatite and titanium on zirconia (HTOZ) to bond to bone under load-bearing conditions in animal experiments. HTOZ, HA, and Ti on Co-Cr alloy (HTOC) and Ti on Co-Cr alloy (TOC) were implanted into the weight-bearing portion of the femoral condyles of nine beagle dogs. Femurs were extracted 4, 12, and 52 weeks after implantation and examined mechanically by pullout testing, and histologically by toluidine blue staining, SEM, and calculation of the affinity index. The interfacial shear strengths (mean+/-SD) of the HTOZ, HTOC, and TOC groups were 4.42+/-0.453, 3.90+/-0.903, and 4.08+/-0.790 MPa at 4 weeks; 6.82+/-2.64, 6.00+/-1.88, and 6.63+/-1.63 MPa at 12 weeks; and 13.98+/-1.94, 11.95+/-1.51, and 10.78+/-0.83 MPa at 52 weeks. There were no significant differences in the interfacial shear strengths between the three groups at any time. Affinity indices (mean+/-SD) obtained from SEM images of the HTOZ, HTOC, and TOC groups were 49.6+/-6.52%, 43.3+/-10.43%, and 23.7+/-3.95% at 4 weeks; 55.0+/-6.72%, 51.5+/-3.07%, and 28.6+/-4.09% at 12 weeks; and 59.1+/-6.73%, 63.0+/-6.40%, and 34.3+/-6.72% at 52 weeks. HA-coated implants (HTOZ, HTOC) had significantly higher affinity indices than non-HA-coated implants (TOC) at all times. HTOZ has the ability to bond to bone equivalent to HTOC and TOC. HTOZ is an excellent material for components of cementless joint prostheses.

  20. Turbulent rotating plane Couette flow: Reynolds and rotation number dependency of flow structure and momentum transport

    NASA Astrophysics Data System (ADS)

    Kawata, Takuya; Alfredsson, P. Henrik

    2016-07-01

    Plane Couette flow under spanwise, anticyclonic system rotation [rotating plane Couette flow (RPCF)] is studied experimentally using stereoscopic particle image velocimetry for different Reynolds and rotation numbers in the fully turbulent regime. Similar to the laminar regime, the turbulent flow in RPCF is characterized by roll cells, however both instantaneous snapshots of the velocity field and space correlations show that the roll cell structure varies with the rotation number. All three velocity components are measured and both the mean flow and all four nonzero Reynolds stresses are obtained across the central parts of the channel. This also allows us to determine the wall shear stress from the viscous stress and the Reynolds stress in the center of the channel, and for low rotation rates the wall shear stress increases with increasing rotation rate as expected. The results show that zero absolute vorticity is established in the central parts of the channel of turbulent RPCF for high enough rotation rates, but also that the mean velocity profile for certain parameter ranges shows an S shape giving rise to a negative velocity gradient in the center of the channel. We find that from an analysis of the Reynolds stress transport equation using the present data there is a transport of the Reynolds shear stress towards the center of the channel, which may then result in a negative mean velocity gradient there.

  1. Principles of Z-plane technology and on-sensor processing for photoelectric structures with memory

    NASA Astrophysics Data System (ADS)

    Vinogradov, Sergey L.; Shubin, Vitaly E.

    1996-06-01

    Novel integrated intelligent videosensor and its possible application using on-FPA real-time parallel processing are discussed. This solid-state single-chip sensor is photoelectric structure with memory (PESM), which consists of semiconductor, insulator and metal layers, wherein optical information are detected, recorded and stored in the form of 2D charge and potential patterns, and then processed due to internal interaction of these patterns in a normal direction to the input plane. Thus, such Z-plane technology allows the PESM to operate as multifunctional device utilizing massively parallel processing with high effective operational speed (up to 10(superscript 14) operation/bit/s) without additional electronic and computing units. Except reading, writing and storing, PESM performs such parallel image processing as summation, subtraction, contouring, convolution and correlation, which may be effectively applied to numerous tasks of diverse optoelectronic systems. Two image operations--subtraction and correlation, which seems to us of high importance, are demonstrated as an example of the PESM performance. It allows one to solve in a real time the main problems concerned with background subtraction, moving object selection, target tracking and pointing, recognition of extended objects and so on. As we suppose, the possible applications of the PESM as an intellectual `supersensor', which combines a high-quality imager and a high-capacity multifunctional processor, would provide substantially lower prime cost of the designed systems in comparison with the now-existing ones and may be widely extended.

  2. Investigation of flaw geometry and loading effects on plane strain fracture in metallic structures

    NASA Technical Reports Server (NTRS)

    Hall, L. R.; Finger, R. W.

    1971-01-01

    The effects on fracture and flaw growth of weld-induced residual stresses, combined bending and tension stresses, and stress fields adjacent to circular holes in 2219-T87 aluminum and 5AI-2.5Sn(ELI) titanium alloys were evaluated. Static fracture tests were conducted in liquid nitrogen; fatigue tests were performed in room air, liquid nitrogen, and liquid hydrogen. Evaluation of results was based on linear elastic fracture mechanics concepts and was directed to improving existing methods of estimating minimum fracture strength and fatigue lives for pressurized structure in spacecraft and booster systems. Effects of specimen design in plane-strain fracture toughness testing were investigated. Four different specimen types were tested in room air, liquid nitrogen and liquid hydrogen environments using the aluminum and titanium alloys. Interferometry and holograph were used to measure crack-opening displacements in surface-flawed plexiglass test specimens. Comparisons were made between stress intensities calculated using displacement measurements, and approximate analytical solutions.

  3. Plane-wave DFT-LDA calculation of the electronic structure and absorption spectrum of copper

    NASA Astrophysics Data System (ADS)

    Marini, Andrea; Onida, Giovanni; del Sole, Rodolfo

    2001-11-01

    We present an accurate, first-principles study of the electronic structure and absorption spectrum of bulk copper within density functional theory in the local density approximation, including the study of intraband transitions. We construct norm-conserving pseudopotentials (PP's) including the 3d shell (and optionally the underlying 3s and 3p shells) in the valence and requiring a relatively small plane-wave basis (60 and 140 Ry cutoff, respectively). As a consequence, these PP's are strongly nonlocal, yielding macroscopically wrong results in the absorption spectrum when momentum matrix elements are computed naively. Our results are compared with experimental photoemission, absorption, and electron energy loss data, and suggest nontrivial self-energy effects in the quasiparticle spectrum of Cu.

  4. Dislocation Core Structure and Peierls Stress of B2-Based AlSc in {110} Plane

    NASA Astrophysics Data System (ADS)

    Li, S. R.; Wu, X. Z.; Zhang, T.; Tian, Y. X.; Yan, Z. X.; Zhu, H. Z.

    2016-10-01

    The core structure and Peierls stress of <100>, <110>, and <111> dislocations in {110} plane of B2-based AlSc (B2-AlSc) have been investigated using improved dislocation equations combined with the generalized stacking fault (GSF) energy. The truncated approximation method is utilized to construct the dissociated and undissociated dislocations in AlSc, then the effects of dislocation angles on the elastic strain energy and misfit energy are presented. Specifically, with increasing dislocation angle, the misfit energy, elastic strain energy, and total energy, and their corresponding stresses, decrease on the <100>{110} and <110>{110} slip systems. However, for <111>{110} dislocation, all energies and corresponding stresses exhibit the relationship 0° > 54.7° > 35.3° > 90°. The misfit energy is always smaller than the elastic strain energy, even by one or two orders of magnitude, and their phases are always opposite.

  5. Dynamics of a passive micro-vibration isolator based on a pretensioned plane cable net structure and fluid damper

    NASA Astrophysics Data System (ADS)

    Chen, Yanhao; Lu, Qi; Jing, Bo; Zhang, Zhiyi

    2016-09-01

    This paper addresses dynamic modelling and experiments on a passive vibration isolator for application in the space environment. The isolator is composed of a pretensioned plane cable net structure and a fluid damper in parallel. Firstly, the frequency response function (FRF) of a single cable is analysed according to the string theory, and the FRF synthesis method is adopted to establish a dynamic model of the plane cable net structure. Secondly, the equivalent damping coefficient of the fluid damper is analysed. Thirdly, experiments are carried out to compare the plane cable net structure, the fluid damper and the vibration isolator formed by the net and the damper, respectively. It is shown that the plane cable net structure can achieve substantial vibration attenuation but has a great amplification at its resonance frequency due to the light damping of cables. The damping effect of fluid damper is acceptable without taking the poor carrying capacity into consideration. Compared to the plane cable net structure and the fluid damper, the isolator has an acceptable resonance amplification as well as vibration attenuation.

  6. Inertial effects on thin-film wave structures with imposed surface shear on an inclined plane

    NASA Astrophysics Data System (ADS)

    Sivapuratharasu, M.; Hibberd, S.; Hubbard, M. E.; Power, H.

    2016-06-01

    This study provides an extended approach to the mathematical simulation of thin-film flow on a flat inclined plane relevant to flows subject to high surface shear. Motivated by modelling thin-film structures within an industrial context, wave structures are investigated for flows with moderate inertial effects and small film depth aspect ratio ε. Approximations are made assuming a Reynolds number, Re ∼ O(ε-1) and depth-averaging used to simplify the governing Navier-Stokes equations. A parallel Stokes flow is expected in the absence of any wave disturbance and a generalisation for the flow is based on a local quadratic profile. This approach provides a more general system which includes inertial effects and is solved numerically. Flow structures are compared with studies for Stokes flow in the limit of negligible inertial effects. Both two-tier and three-tier wave disturbances are used to study film profile evolution. A parametric study is provided for wave disturbances with increasing film Reynolds number. An evaluation of standing wave and transient film profiles is undertaken and identifies new profiles not previously predicted when inertial effects are neglected.

  7. Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading

    PubMed Central

    DITTMER, Marc Philipp; NENSA, Moritz; STIESCH, Meike; KOHORST, Philipp

    2013-01-01

    Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. Objective The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. Material and Methods Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05). Results All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. Conclusion The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo

  8. Adhesive strength of bone-implant interfaces and in-vivo degradation of PHB composites for load-bearing applications.

    PubMed

    Meischel, M; Eichler, J; Martinelli, E; Karr, U; Weigel, J; Schmöller, G; Tschegg, E K; Fischerauer, S; Weinberg, A M; Stanzl-Tschegg, S E

    2016-01-01

    Aim of this study was to evaluate the response of bone to novel biodegradable polymeric composite implants in the femora of growing rats. Longitudinal observation of bone reaction at the implant site (BV/TV) as well as resorption of the implanted pins were monitored using in vivo micro-focus computed tomography (µCT). After 12, 24 and 36 weeks femora containing the implants were explanted, scanned with high resolution ex vivo µCT, and the surface roughness of the implants was measured to conclude on the ingrowth capability for bone tissue. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to observe changes on the surface of Polyhydroxybutyrate (PHB) during degradation and cell ingrowth. Four different composites with zirconium dioxide (ZrO2) and Herafill(®) were compared. After 36 weeks in vivo, none of the implants did show significant degradation. The PHB composite with ZrO2 and a high percentage (30%) of Herafill® as well as the Mg-alloy WZ21 showed the highest values of bone accumulation (increased BV/TV) around the implant. The lowest value was measured in PHB with 3% ZrO2 containing no Herafill®. Roughness measurements as well as EDX and SEM imaging could not reveal any changes on the PHB composites׳ surfaces. Biomechanical parameters, such as the adhesion strength between bone and implant were determined by measuring the shear strength as well as push-out energy of the bone-implant interface. The results showed that improvement of these mechanical properties of the studied PHBs P3Z, P3Z10H and P3Z30H is necessary in order to obtain appropriate load-bearing material. The moduli of elasticity, tensile strength and strain properties of the PHB composites are close to that of bone and thus promising. Compared to clinically used PLGA, PGA and PLA materials, their additional benefit is an unchanged local pH value during degradation, which makes them well tolerated by cells and immune system. They might be used

  9. Anatomical sector analysis of load-bearing tibial bone structure during 90-day bed rest and 1-year recovery.

    PubMed

    Cervinka, Tomas; Rittweger, Jörn; Hyttinen, Jari; Felsenberg, Dieter; Sievänen, Harri

    2011-07-01

    The aim of this study was to investigate whether the bone response to long bed rest-related immobility and during subsequent recovery differed at anatomically different sectors of tibial epiphysis and diaphysis. For this study, peripheral quantitative tomographic (pQCT) scans obtained from a previous 90-day 'Long Term Bed Rest' intervention were preprocessed with a new method based on statistical approach and re-analysed sector-wise. The pQCT was performed on 25 young healthy males twice before the bed rest, after the bed rest and after 1-year follow-up. All men underwent a strict bed rest intervention, and in addition, seven of them received pamidronate treatment and nine did flywheel exercises as countermeasures against disuse-related bone loss. Clearly, 3-9% sector-specific losses in trabecular density were observed at the tibial epiphysis on average. Similarly, cortical density decreased in a sector-specific way being the largest at the anterior sector of tibial diaphysis. During recovery, the bed rest-induced bone losses were practically restored and no consistent sector-specific modulation was observed in any subgroup. It is concluded that the sector-specific analysis of bone cross-sections has potential to reveal skeletal responses to various interventions that cannot be inferred from the average analysis of the whole bone cross-section. This approach is considered also useful for evaluating the bone responses from the biomechanical point of view. PMID:21672131

  10. Structure of exhaust jets produced by magnetic reconnection localized in the out-of-plane direction

    NASA Astrophysics Data System (ADS)

    Pritchett, P. L.

    2015-01-01

    Three-dimensional electromagnetic particle-in-cell simulations are used to investigate the structure of exhaust jets produced by magnetic reconnection localized in the out-of-plane direction. The localized reconnection is produced by periodically blocking the cross-tail current density, a procedure that has effects analogous to those produced by the assumption of a region of anomalous resistivity in fluid treatments of reconnection. The width of the blocking region is varied between 4 and 24di, where di is the ion inertial length. After an initial displacement in the electron-drift direction, the jet front undergoes a marked expansion in the ion-drift direction, reaching a total cross-tail width of 15-20di regardless of the initial width. The jet front breaks up into small-scale finger structures of the order of 1-2di in width, which appears to be due to the action of the ballooning/interchange instability. Ahead of the front, the ion pressure Pixx is increased due to reflection of ions from the moving front and the penetration of high-speed ions in the jet through the front. The ion temperature Tixx exhibits a minimum within the front, while the electron temperature is enhanced in the front. The properties of the reconnection-generated fronts are compared and contrasted with those of interchange heads produced by a decreasing entropy profile.

  11. Structural and morphological characteristics of planar (112¯0) a-plane gallium nitride grown by hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Haskell, B. A.; Wu, F.; Matsuda, S.; Craven, M. D.; Fini, P. T.; DenBaars, S. P.; Speck, J. S.; Nakamura, Shuji

    2003-08-01

    This letter discusses the structural and morphological characteristics of planar, nonpolar (112¯0) a-plane GaN films grown on (11¯02) r-plane sapphire by hydride vapor phase epitaxy. Specular films with thicknesses over 50 μm were grown, eliminating the severely faceted surfaces that have previously been observed for hydride vapor phase epitaxy-grown a-plane films. Internal cracks and crack healing, similar to that in c-plane GaN films, were observed. Atomic force microscopy revealed nanometer-scale pitting and steps on the film surfaces, with rms roughness of ˜2 nm. X-ray diffraction confirmed the films are solely a-plane oriented with on-axis (112¯0) and 30° off-axis (101¯0) rocking curve peak widths of 1040 and 3000 arcsec, respectively. Transmission electron microscopy revealed a typical basal plane stacking fault density of 4×105cm-1. The dislocation content of the films consisted of predominately edge component (bedge=±[0001]) threading dislocations with a density of 2×1010 cm-2, and mixed-character Shockley partial dislocations (b=1/3<11¯00>) with a density of 7×109 cm-2.

  12. Giant magnetroresistance properties of specular spin valve films in a current perpendicular to plane structure

    SciTech Connect

    Nagasaka, K.; Seyama, Y.; Varga, L.; Shimizu, Y.; Tanaka, A.

    2001-06-01

    Conventional and specular spin valve films in a current perpendicular to plane (CPP) structure have been investigated. The specular spin valve film with bottom type structure had two oxidized layers: one in the pinned layer, which was oxidized during an in situ deposition process, and the other in the free layer, which was a naturally oxidized Cu/Ta cap. Both films had increasing resistance, R, and resistance change, {Delta}R, with decreasing element size. The conventional spin valve film showed a resistance times area product, RA, of 144 m{Omega}{mu}m2 and a resistance change area product, {Delta}RA, of 0.7 m{Omega}{mu}m2 while the specular spin valve film showed RA of 1120 m{Omega}{mu}m2 and {Delta}RA of 23 m{Omega}{mu}m2. The {Delta}RA of the specular spin valve film was about 33 times larger than that of the conventional spin valve film. The calculated magnetoresistance (MR) ratios, MR{sub SV}, of each spin valve film were 1.9% and 2.3%, respectively. We think oxidized layers in the spin valve film caused the specular electron scattering and this lengthened the path of the conduction electrons, enhancing the interfacial and bulk spin dependent scattering. We estimated the output voltage change of the 0.01 {mu}m2 element, the size required for 150 Gb/in.2 recording density, of the specular spin valve film in CPP mode to be 5.3 mV. It was almost six times larger than that of the conventional spin valve film at constant power consumption. Specular spin valve film are advantageous for the CPP structure element for future giant MR sensors. {copyright} 2001 American Institute of Physics.

  13. GaN m -plane: Atomic structure, surface bands, and optical response

    NASA Astrophysics Data System (ADS)

    Landmann, M.; Rauls, E.; Schmidt, W. Â. G.; Neumann, M. Â. D.; Speiser, E.; Esser, N.

    2015-01-01

    Density-functional-theory calculations are combined with many-body perturbation theory in order to elucidate the geometry, electronic, and optical properties of the w z -GaN (1 1 ¯00 ) surface, i.e., the so-called m -plane. The optical absorption and reflection anisotropy related to electronic transitions between surface states are identified by comparison with measured data covering transition energies from 2.4 up to 5.4 eV. Our results show a surface relaxation mechanism consistent with the electron counting rule that causes a moderate buckling of the GaN surface dimers and gives rise to two distinct surface states: The doubly occupied N dangling bonds form a surface band that is resonant with the GaN valence-band edge at the center of the Brillouin zone, whereas the empty Ga dangling bonds occur within the GaN band gap closely following the dispersion of the conduction-band edge. These two states contribute strongly to the formation of surface excitons that redshift the optical absorption with respect to the bulk optical response. The surface optical absorption i.e., the excitonic onset below the bulk band gap followed by a broad absorption band at higher energies related to the dispersion of the surface band structure, is calculated in agreement with the experimental data.

  14. Transverse plane of apical vertebra of structural thoracic curve: vertebra displacement versus vertebral deformation.

    PubMed

    Kotwicki, Tomasz; Napiontek, Marek; Nowakowski, Andrzej

    2006-01-01

    CT transversal scans of the trunk provided at the level of Th8 or Th9 (apical vertebra) of 23 patients with structural thoracic scoliosis were reviewed. The following parameters were studied: 1) alpha angle formed by the axis of vertebra and the axis of spinous process, 2) beta concave and beta convex angle between the spinous process and the left and right transverse process respectively, 3) gamma concave and gamma convex angle between the axis of vertebra and the left and right transverse process respectively, 4) rotation angle to the sagittal plane according to Aaro and Dahlborn, 5) Cobb angle. Values of measured parameters demonstrated a common pattern of intravertebral deformity: counter clockwise deviation of the spinous process (alpha angle 15,0 +/-8,5 degrees), beta concave (69,8 +/-8,5 degrees) significantly greater than beta convex (38,8 +/-8,5 degrees), gamma concave (54,3 +/-7,8 degrees) not different from gamma convex (56,0 +/-8,0 degrees). Strong linear positive correlation between alpha angle and Aaro-Dahlborn angle was observed (r=0,78, p<0,05). Changes in morphology of apical vertebra due to intravertebral bone remodelling followed the vertebral spatial displacement and there existed a linear correlation in between. The two processes develop in opposite directions. PMID:17108421

  15. Turbulent statistics and flow structures in spanwise-rotating turbulent plane Couette flows

    NASA Astrophysics Data System (ADS)

    Gai, Jie; Xia, Zhenhua; Cai, Qingdong; Chen, Shiyi

    2016-09-01

    A series of direct numerical simulations of spanwise-rotating turbulent plane Couette flows at a Reynolds number of 1300 with rotation numbers Ro between 0 and 0.9 is carried out to investigate the effects of anticyclonic rotation on turbulent statistics and flow structures. Several typical turbulent statistics are presented, including the mean shear rate at the centerline, the wall-friction Reynolds number, and volume-averaged kinetic energies with respect to the secondary flow field, turbulent field, and total fluctuation field. Our results show that the rotation changes these quantities in different manners. Volume-averaged balance equations for kinetic energy are analyzed and it turns out that the interaction term acts as a kinetic energy bridge that transfers energy from the secondary flow to the turbulent fluctuations. Several typical flow regimes are identified based on the correlation functions across the whole channel and flow visualizations. The two-dimensional roll cells are observed at weak rotation Ro=0.01 , where alternant clustering of vortices appears. Three-dimensional roll cells emerge around Ro≈0.02 , where the clustering of vortices shows the meandering and bifurcating behavior. For moderate rotation 0.07 ≲Ro≲0.36 , well-organized structures are observed, where the herringbonelike vortices are clustered between streaks from the top view of three-dimensional flow visualization and form annuluses. More importantly, the vortices are rather confined to one side of the walls when Ro≤0.02 and are inclined from the bottom to upper walls when Ro≥0.07 .

  16. Evaluation of the Load-bearing Capacity of Fractured Incisal Edge of Maxillary Permanent Central Incisors restored with a Glass Fiber-reinforced Nanocomposite: An in vitro Study

    PubMed Central

    Srilatha, KT; Nandlal, B; Dhull, Kanika Singh

    2015-01-01

    ABSTRACT Objectives: The aim of this study was to evaluate and compare the load-bearing capacity of fractured incisal edge of maxillary permanent central incisors restored with a nanocomposite and a glass fiber-reinforced nanocomposite. Materials and methods: Thirty-six extracted sound maxillary central incisors randomly divided in three groups were used for the present study. Group I (control) contained untreated teeth. Samples in experimental groups II and III were prepared by cutting the incisal (one-third) part of the crown horizontally and subjected to enamel preparations and restored with a nanocomposite and a glass fiber-reinforced nanocomposite respectively. All restored teeth were stored in distilled water at room temperature for 24 hours. Fracture resistance was evaluated as peak load at failure (Newton) for samples tested in a cantilever-bending test using Hounsfield universal testing machine. Failure modes were microscopically examined. Results: Highest mean peak failure load (Newton) among experimental groups was observed in glass fiber-reinforced nano composite group (863.50 ± 76.12 N) followed by nanocomposite group (633.67 ± 40.14 N). One-way analysis of variance (ANOVA) revealed that the restoration technique significantly affected the load-bearing capacity (p < 0.001). Scheffe’s post-hoc comparison test (subset for α = 0.05) revealed that there was significant difference in the mean peak failure load values of nanocomposite and glass fiber-reinforced nanocomposite groups when considered together (p < 0.001). Experimental groups showed similar types of failure modes with majority occurring ascohesive and mixed type. Fifty-eight percent of the teeth in glass fiber-reinforced nanocomposite group fractured below the cementoenamel junction. Conclusion: By using fiber-reinforced composite substructure under conventional composites in the repair of fractured incisors, the load-bearing capacity of the restored incisal edge could be substantially

  17. Detection of trans–cis flips and peptide-plane flips in protein structures

    SciTech Connect

    Touw, Wouter G.; Joosten, Robbie P.; Vriend, Gert

    2015-07-28

    A method is presented to detect peptide bonds that need either a trans–cis flip or a peptide-plane flip. A coordinate-based method is presented to detect peptide bonds that need correction either by a peptide-plane flip or by a trans–cis inversion of the peptide bond. When applied to the whole Protein Data Bank, the method predicts 4617 trans–cis flips and many thousands of hitherto unknown peptide-plane flips. A few examples are highlighted for which a correction of the peptide-plane geometry leads to a correction of the understanding of the structure–function relation. All data, including 1088 manually validated cases, are freely available and the method is available from a web server, a web-service interface and through WHAT-CHECK.

  18. Simultaneous in-plane and out-of-plane displacement measurement based on a dual-camera imaging system and its application to inspection of large-scale space structures

    NASA Astrophysics Data System (ADS)

    Ri, Shien; Tsuda, Hiroshi; Yoshida, Takeshi; Umebayashi, Takashi; Sato, Akiyoshi; Sato, Eiichi

    2015-07-01

    Optical methods providing full-field deformation data have potentially enormous interest for mechanical engineers. In this study, an in-plane and out-of-plane displacement measurement method based on a dual-camera imaging system is proposed. The in-plane and out-of-plane displacements are determined simultaneously using two measured in-plane displacement data observed from two digital cameras at different view angles. The fundamental measurement principle and experimental results of accuracy confirmation are presented. In addition, we applied this method to the displacement measurement in a static loading and bending test of a solid rocket motor case (CFRP material; 2.2 m diameter and 2.3 m long) for an up-to-date Epsilon rocket developed by JAXA. The effectiveness and measurement accuracy is confirmed by comparing with conventional displacement sensor. This method could be useful to diagnose the reliability of large-scale space structures in the rocket development.

  19. Repair of segmental load-bearing bone defect by autologous mesenchymal stem cells and plasma-derived fibrin impregnated ceramic block results in early recovery of limb function.

    PubMed

    Ng, Min Hwei; Duski, Suryasmi; Tan, Kok Keong; Yusof, Mohd Reusmaazran; Low, Kiat Cheong; Rose, Isa Mohamed; Mohamed, Zahiah; Bin Saim, Aminuddin; Idrus, Ruszymah Bt Hj

    2014-01-01

    Calcium phosphate-based bone substitutes have not been used to repair load-bearing bone defects due to their weak mechanical property. In this study, we reevaluated the functional outcomes of combining ceramic block with osteogenic-induced mesenchymal stem cells and platelet-rich plasma (TEB) to repair critical-sized segmental tibial defect. Comparisons were made with fresh marrow-impregnated ceramic block (MIC) and partially demineralized allogeneic bone block (ALLO). Six New Zealand White female rabbits were used in each study group and three rabbits with no implants were used as negative controls. By Day 90, 4/6 rabbits in TEB group and 2/6 in ALLO and MIC groups resumed normal gait pattern. Union was achieved significantly faster in TEB group with a radiological score of 4.50 ± 0.78 versus ALLO (1.06 ± 0.32), MIC (1.28 ± 0.24), and negative controls (0). Histologically, TEB group scored the highest percentage of new bone (82% ± 5.1%) compared to ALLO (5% ± 2.5%) and MIC (26% ± 5.2%). Biomechanically, TEB-treated tibiae achieved the highest compressive strength (43.50 ± 12.72 MPa) compared to those treated with ALLO (15.15 ± 3.57 MPa) and MIC (23.28 ± 6.14 MPa). In conclusion, TEB can repair critical-sized segmental load-bearing bone defects and restore limb function.

  20. Octupolar out-of-plane magnetic field structure generation during collisionless magnetic reconnection in a stressed X-point collapse

    SciTech Connect

    Graf von der Pahlen, J.; Tsiklauri, D.

    2014-06-15

    The out-of-plane magnetic field, generated by fast magnetic reconnection, during collisionless, stressed X-point collapse, was studied with a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code, using both closed (flux conserving) and open boundary conditions on a square grid. It was discovered that the well known quadrupolar structure in the out-of-plane magnetic field gains four additional regions of opposite magnetic polarity, emerging near the corners of the simulation box, moving towards the X-point. The emerging, outer, magnetic field structure has opposite polarity to the inner quadrupolar structure, leading to an overall octupolar structure. Using Ampere's law and integrating electron and ion currents, defined at grid cells, over the simulation domain, contributions to the out-of-plane magnetic field from electron and ion currents were determined. The emerging regions of opposite magnetic polarity were shown to be the result of ion currents. Magnetic octupolar structure is found to be a signature of X-point collapse, rather than tearing mode, and factors relating to potential discoveries in experimental scenarios or space-craft observations are discussed.

  1. Detection of trans–cis flips and peptide-plane flips in protein structures

    PubMed Central

    Touw, Wouter G.; Joosten, Robbie P.; Vriend, Gert

    2015-01-01

    A coordinate-based method is presented to detect peptide bonds that need correction either by a peptide-plane flip or by a trans–cis inversion of the peptide bond. When applied to the whole Protein Data Bank, the method predicts 4617 trans–cis flips and many thousands of hitherto unknown peptide-plane flips. A few examples are highlighted for which a correction of the peptide-plane geometry leads to a correction of the understanding of the structure–function relation. All data, including 1088 manually validated cases, are freely available and the method is available from a web server, a web-service interface and through WHAT_CHECK. PMID:26249342

  2. Modulating Magnetic Properties by Tailoring In-Plane Domain Structures in Hexagonal YMnO3 Films.

    PubMed

    Deng, Shiqing; Cheng, Shaobo; Liu, Ming; Zhu, Jing

    2016-09-28

    Periodic structures and the coupling of multiorder parameters in complex oxides heterojunctions can generate exotic properties, of interest both for fundamental researches and for device applications. Here, we report a self-assembling in-plane periodic domain structure, and the resulting rich magnetic states, in a h-YMnO3 thin film fabricated on c-face sapphire substrate. Detailed structural investigations at atomic-level reveal the fashion of alternating domains under tensile or compressive strains separated by a boundary region. Tuned by this in-plane domain structure, the abnormal magnetic properties, such as the ferromagnetic enhancement and the unexpected spin glass state (below ∼38 K), are realized. Moreover, the existence of ferroelectric polarization is confirmed by scanning transmission electron microscopy, which brings in the chances of magnetoelectric coupling effect. These results manifest the close connections between the magnetic properties and such in-plane microstructures, suggesting the possibility of tuning the coupling effects via strain engineering in the hexagonal manganite film. PMID:27608731

  3. The use of the plane wave fluid-structure interaction loading approximation in NASTRAN

    NASA Technical Reports Server (NTRS)

    Dawson, R. L.

    1991-01-01

    The Plane Wave Approximation (PWA) is widely used in finite element analysis to implement the loading generated by an underwater shock wave. The method required to implement the PWA in NASTRAN is presented along with example problems. A theoretical background is provided and the limitations of the PWA are discussed.

  4. [Architectural structure of the pterygoidian plane of the masticatory musculature in the cat (Felis catus L.)].

    PubMed

    Lautrou, A; Laison, F

    1975-09-01

    The architectural analysis of the ptérygoidal plane of the cat identified the two pterygoid muscles. The medial pterygoid showed an orbital and an angular part inserted respectively on the internal face of the mandibule and on the maeto-angular ligament. The lateral pterygoid consisted of only one pterygoid bundle, involved in lateral movements and adjustments of the jaw condyle.

  5. Comparative study of fracture planes computed from topography and lineaments from imagery with structures and mineralization in the magnetic belt of Washington State

    SciTech Connect

    Eliason, J.R.; Eliason, V.L.

    1985-04-01

    Digitally computed fracture planes for the Magnesite Belt of Washington State were obtained using a technique developed for structural geologic analysis of topography. These planes and lineaments, interpreted from aerial and satellite data sets, have been compared to mapped structures and mineralization in the area. The Magnesite Belt of Stevens County, Washington, was selected for this study because detailed joint analysis studies had been conducted in this area. These studies included measurement and analysis of over 2000 joints in the area. Computed fracture planes were used to develop a structural model for fracturing in the region. These planes clearly indicate that the region is dominated by normal faulting. Lineaments mapped in the area show a dominant North 30/sup 0/ East trend which correlates with mineralization in the region and the dominant computed longitudinal fracture plane trends. These predicted longitudinal fracture planes show a strong spatial correlation with the major magnesite mineralization. 11 refs., 14 figs., 1 tab.

  6. Plane-wave expansion method for calculating band structure of photonic crystal slabs with perfectly matched layers.

    PubMed

    Shi, Shouyuan; Chen, Caihua; Prather, Dennis W

    2004-09-01

    We present a new algorithm for calculation of the band structure of photonic crystal slabs. This algorithm combines the plane-wave expansion method with perfectly matched layers for the termination of the computational region in the direction out of the plane. In addition, the effective-medium tensor is applied to improve convergence. A general complex eigenvalue problem is then obtained. Two criteria are presented to distinguish the guided modes from the PML modes. As such, this scheme can accurately determine the band structure both above and below the light cone. The convergence of the algorithm presented has been studied. The results obtained by using this algorithm have been compared with those obtained by the finite-difference time-domain method and found to agree very well.

  7. Study of the in-plane magnetic structure of a layered system using polarized neutron scattering under grazing incidence geometry

    NASA Astrophysics Data System (ADS)

    Maruyama, R.; Bigault, T.; Wildes, A. R.; Dewhurst, C. D.; Soyama, K.; Courtois, P.

    2016-05-01

    The in-plane magnetic structure of a layered system with a polycrystalline grain size less than the ferromagnetic exchange length was investigated using polarized neutron off-specular scattering and grazing incidence small angle scattering measurements to gain insight into the mechanism that controls the magnetic properties which are different from the bulk. These complementary measurements with different length scales and the data analysis based on the distorted wave Born approximation revealed the lateral correlation on a length scale of sub- μm due to the fluctuating orientation of the magnetization in the layer. The obtained in-plane magnetic structure is consistent with the random anisotropy model, i.e. competition between the exchange interactions between neighboring spins and the local magnetocrystalline anisotropy.

  8. Planes formed with four intron-positions in tertiary structures of retinol binding protein and calpain domain VI.

    PubMed

    Nosaka, Michiko; Hirata, Katsuki; Tsuji, Ryotarou; Sunaba, Syunya

    2014-01-01

    Eukaryotic genes have intervening sequences, introns, in their coding regions. Since introns are spliced out from m-RNA before translation, they are considered to have no effect on the protein structure. Here, we report a novel relationship between introns and the tertiary structures of retinol binding protein and calpain domain VI. We identified "intron-positions" as amino acid residues on which or just after which introns are found in their corresponding nucleotide sequences, and then found that four intron-positions form a plane. We also found that the four intron-positions of retinol-binding protein encloses its ligand retinol. The tertiary structure of calpain domain VI changes after Ca(2+) binding, and the four intron-positions form a plane that includes its ligand calpastatin. To evaluate the statistical significance of the planarity, we calculated the mean distance of each intron-position from the plane defined by the other three intron-positions, and showed that it is significantly smaller than the one calculated for randomly generated locations based on exon size distribution. On the basis of this finding, we discuss the evolution of retinol binding protein and the origin of introns.

  9. In-plane chemical pressure essential for superconductivity in BiCh2-based (Ch: S, Se) layered structure

    PubMed Central

    Mizuguchi, Yoshikazu; Miura, Akira; Kajitani, Joe; Hiroi, Takafumi; Miura, Osuke; Tadanaga, Kiyoharu; Kumada, Nobuhiro; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2015-01-01

    BiCh2-based compounds (Ch: S, Se) are a new series of layered superconductors, and the mechanisms for the emergence of superconductivity in these materials have not yet been elucidated. In this study, we investigate the relationship between crystal structure and superconducting properties of the BiCh2-based superconductor family, specifically, optimally doped Ce1−xNdxO0.5F0.5BiS2 and LaO0.5F0.5Bi(S1−ySey)2. We use powder synchrotron X-ray diffraction to determine the crystal structures. We show that the structure parameter essential for the emergence of bulk superconductivity in both systems is the in-plane chemical pressure, rather than Bi-Ch bond lengths or in-plane Ch-Bi-Ch bond angle. Furthermore, we show that the superconducting transition temperature for all REO0.5F0.5BiCh2 superconductors can be determined from the in-plane chemical pressure. PMID:26447333

  10. Remarkable shape-sustaining, load-bearing, and self-healing properties displayed by a supramolecular gel derived from a bis-pyridyl-bis-amide of L-phenyl alanine.

    PubMed

    Das, Uttam Kumar; Banerjee, Subhabrata; Dastidar, Parthasarathi

    2014-09-01

    A series of bis-amides decorated with pyridyl and phenyl moieties derived from L-amino acids having an innocent side chain (L-alanine and L-phenyl alanine) were synthesized as potential low-molecular-weight gelators (LMWGs). Both protic and aprotic solvents were found to be gelled by most of the bis-amides with moderate to excellent gelation efficiency (minimum gelator concentration=0.32-4.0 wt.% and gel-sol dissociation temperature T(gel)=52-110 °C). The gels were characterized by rheology, DSC, SEM, TEM, and temperature-variable (1)H NMR measurements. pH-dependent gelation studies revealed that the pyridyl moieties took part in gelation. Structure-property correlation was attempted using single-crystal X-ray and powder X-ray diffraction data. Remarkably, one of the bis-pyridyl bis-amide gelators, namely 3,3-Phe (3-pyridyl bis-amide of L-phenylalanine) displayed outstanding shape-sustaining, load-bearing, and self-healing properties. PMID:24962554

  11. Remarkable shape-sustaining, load-bearing, and self-healing properties displayed by a supramolecular gel derived from a bis-pyridyl-bis-amide of L-phenyl alanine.

    PubMed

    Das, Uttam Kumar; Banerjee, Subhabrata; Dastidar, Parthasarathi

    2014-09-01

    A series of bis-amides decorated with pyridyl and phenyl moieties derived from L-amino acids having an innocent side chain (L-alanine and L-phenyl alanine) were synthesized as potential low-molecular-weight gelators (LMWGs). Both protic and aprotic solvents were found to be gelled by most of the bis-amides with moderate to excellent gelation efficiency (minimum gelator concentration=0.32-4.0 wt.% and gel-sol dissociation temperature T(gel)=52-110 °C). The gels were characterized by rheology, DSC, SEM, TEM, and temperature-variable (1)H NMR measurements. pH-dependent gelation studies revealed that the pyridyl moieties took part in gelation. Structure-property correlation was attempted using single-crystal X-ray and powder X-ray diffraction data. Remarkably, one of the bis-pyridyl bis-amide gelators, namely 3,3-Phe (3-pyridyl bis-amide of L-phenylalanine) displayed outstanding shape-sustaining, load-bearing, and self-healing properties.

  12. Fabrication and optical transmission characteristics of polymers woodpile photonic crystal structures with different crystal planes

    NASA Astrophysics Data System (ADS)

    Chen, Ling-Jing; Dong, Xian-Zi; Zhao, Yuan-Yuan; Zhang, Yong-Liang; Liu, Jie; Zheng, Mei-Ling; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2015-10-01

    The photonic band gap effect which originates from the translational invariance of the periodic lattice of dielectrics has been widely applied in the technical applications of microwave, telecommunication and visible wavelengths. Among the various examples, polymers based three dimensional (3D) photonic crystals (PhCs) have attracted considerable interest because they can be easily fabricated by femo-second (fs) ultrafast laser direct writing (DLW) method. However, it is difficult to realize complete band gap in polymers PhCs due to the low index contrast between polymers and air. Here, we report the design and experimental realization of light's nonreciprocal propagation in woodpile PhCs fabricated with DLW method. Firstly, we fabricated several polymers woodpile PhCs on glass substrate with different crystal planes. The Fourier transform infrared spectroscopy (FTIR) measurements are in agreement with the theoretical predictions, which proves the validity and the accuracy of our DLW method. Further measurements of the transmission spectra with respect to the incident angle reveal that the surface crystal planes and incident wave vectors play important roles in the optical response. Furthermore, we designed and fabricated a 30° PhC wedge. And we find nonreciprocal transmission effect between the forward and backward waves, resulting from the nonsymmetrical refraction of the light in different planes. Our results may find potential applications in future 3D photonic integrated circuits and pave the way for the fabrication of other photonic and optical devices with DLW method.

  13. The effect of design parameters of dynamic pedicle screw systems on kinematics and load bearing: an in vitro study.

    PubMed

    Schilling, C; Krüger, S; Grupp, T M; Duda, G N; Blömer, W; Rohlmann, A

    2011-02-01

    As an alternative treatment for chronic back pain due to disc degeneration motion preserving techniques such as posterior dynamic stabilization (PDS) has been clinically introduced, with the intention to alter the load transfer and the kinematics at the affected level to delay degeneration. However, up to the present, it remains unclear when a PDS is clinically indicated and how the ideal PDS mechanism should be designed to achieve this goal. Therefore, the objective of this study was to compare different PDS devices against rigid fixation to investigate the biomechanical impact of PDS design on stabilization and load transfer in the treated and adjacent cranial segment. Six human lumbar spine specimens (L3-L5) were tested in a spine loading apparatus. In vitro flexibility testing was performed by applying pure bending moments of 7.5 Nm without and with additional preload of 400 N in the three principal motion planes. Four PDS devices, "DYN" (Dynesys(®), Zimmer GmbH, Switzerland), "DSS™" (Paradigm Spine, Wurmlingen, Germany), and two prototypes of dynamic rods, "LSC" with a leaf spring, and "STC" with a spring tube (Aesculap AG, Tuttlingen, Germany), were tested in comparison to a rigid fixation device S(4) (Aesculap AG, Tuttlingen, Germany) "RIG", to the native situation "NAT" and to a defect situation "DEF" of the specimens. The instrumented level was L4-L5. The tested PDS devices comprising a stiffness range for axial stiffness of 10 N/mm to 230 N/mm and for bending stiffness of 3 N/mm to 15 N/mm. Range of motion (ROM), neutral zone (NZ), and intradiscal pressure (IDP) were analyzed for all instrumentation steps and load cases of the instrumented and non-instrumented level. In flexion, extension, and lateral bending, all systems, except STC, showed a significant reduction of ROM and NZ compared to the native situation (p < 0.05). Furthermore, we found no significant difference between DYN and RIG (p > 0.1). In axial rotation, only DSS and STC reduced the ROM

  14. Direct spontaneous growth and interfacial structural properties of inclined GaN nanopillars on r-plane sapphire

    SciTech Connect

    Adikimenakis, A.; Aretouli, K. E.; Tsagaraki, K.; Androulidaki, M.; Georgakilas, A.; Lotsari, A.; Dimitrakopulos, G. P. Kehagias, Th.; Komninou, Ph.

    2015-06-28

    The spontaneous growth of GaN nanopillars (NPs) by direct plasma-assisted molecular beam epitaxy on nitridated r-plane sapphire substrates has been studied. The emanation of metal-polarity NPs from inside an a-plane nonpolar GaN film was found to depend on both the substrate nitridation and the growth conditions. The density of NPs increased with increasing the duration of the nitridation process and the power applied on the radio-frequency plasma source, as well as the III/V flux ratio, while variation of the first two parameters enhanced the roughness of the substrate's surface. Transmission electron microscopy (TEM) techniques were employed to reveal the structural characteristics of the NPs and their nucleation mechanism from steps on the sapphire surface and/or interfacial semipolar GaN nanocrystals. Lattice strain measurements showed a possible Al enrichment of the first 5–6 monolayers of the NPs. By combining cross-sectional and plan-view TEM observations, the three-dimensional model of the NPs was constructed. The orientation relationship and interfacial accommodation between the NPs and the nonpolar a-plane GaN film were also elucidated. The NPs exhibited strong and narrow excitonic emission, suggesting an excellent structural quality.

  15. Repair of Segmental Load-Bearing Bone Defect by Autologous Mesenchymal Stem Cells and Plasma-Derived Fibrin Impregnated Ceramic Block Results in Early Recovery of Limb Function

    PubMed Central

    Ng, Min Hwei; Duski, Suryasmi; Tan, Kok Keong; Yusof, Mohd Reusmaazran; Low, Kiat Cheong; Mohamed Rose, Isa; Mohamed, Zahiah; Bin Saim, Aminuddin; Idrus, Ruszymah Bt Hj

    2014-01-01

    Calcium phosphate-based bone substitutes have not been used to repair load-bearing bone defects due to their weak mechanical property. In this study, we reevaluated the functional outcomes of combining ceramic block with osteogenic-induced mesenchymal stem cells and platelet-rich plasma (TEB) to repair critical-sized segmental tibial defect. Comparisons were made with fresh marrow-impregnated ceramic block (MIC) and partially demineralized allogeneic bone block (ALLO). Six New Zealand White female rabbits were used in each study group and three rabbits with no implants were used as negative controls. By Day 90, 4/6 rabbits in TEB group and 2/6 in ALLO and MIC groups resumed normal gait pattern. Union was achieved significantly faster in TEB group with a radiological score of 4.50 ± 0.78 versus ALLO (1.06 ± 0.32), MIC (1.28 ± 0.24), and negative controls (0). Histologically, TEB group scored the highest percentage of new bone (82% ± 5.1%) compared to ALLO (5% ± 2.5%) and MIC (26% ± 5.2%). Biomechanically, TEB-treated tibiae achieved the highest compressive strength (43.50 ± 12.72 MPa) compared to those treated with ALLO (15.15 ± 3.57 MPa) and MIC (23.28 ± 6.14 MPa). In conclusion, TEB can repair critical-sized segmental load-bearing bone defects and restore limb function. PMID:25165699

  16. Gas-liquid two-phase flow structure in the multi-scale weighted complexity entropy causality plane

    NASA Astrophysics Data System (ADS)

    Tang, Yi; Zhao, An; Ren, Ying-yu; Dou, Fu-Xiang; Jin, Ning-De

    2016-05-01

    The multi-scale weighted complexity entropy causality plane (MS-WCECP) is proposed for characterizing the physical structure of complex system. Firstly we use the method to investigate typical nonlinear time series. Compared with the multi-scale complexity entropy causality plane (MS-CECP), the MS-WCECP can not only uncover the dynamic information loss of complex system with the increase of scale, but also can characterize the complexity of nonlinear dynamic system. In particular, the algorithm of MS-WCECP performs strong anti-noise ability. Then we calculate the MS-WCECP for the conductance fluctuating signals measured from vertical upward gas-liquid two-phase flow experiments in a small diameter pipe, the results demonstrate that the MS-WCECP is a useful approach for exploring the stability and complexity in gas-liquid two-phase flows.

  17. A multiple-plane approach to measure the structural properties of functionally active regions in the human cortex.

    PubMed

    Wang, Xin; Garfinkel, Sarah N; King, Anthony P; Angstadt, Mike; Dennis, Michael J; Xie, Hong; Welsh, Robert C; Tamburrino, Marijo B; Liberzon, Israel

    2010-02-15

    Advanced magnetic resonance imaging (MRI) techniques provide the means of studying both the structural and the functional properties of various brain regions, allowing us to address the relationship between the structural changes in human brain regions and the activity of these regions. However, analytical approaches combining functional (fMRI) and structural (sMRI) information are still far from optimal. In order to improve the accuracy of measurement of structural properties in active regions, the current study tested a new analytical approach that repeated a surface-based analysis at multiple planes crossing different depths of cortex. Twelve subjects underwent a fear conditioning study. During these tasks, fMRI and sMRI scans were acquired. The fMRI images were carefully registered to the sMRI images with an additional correction for cortical borders. The fMRI images were then analyzed with the new multiple-plane surface-based approach as compared to the volume-based approach, and the cortical thickness and volume of an active region were measured. The results suggested (1) using an additional correction for cortical borders and an intermediate template image produced an acceptable registration of fMRI and sMRI images; (2) surface-based analysis at multiple depths of cortex revealed more activity than the same analysis at any single depth; (3) projection of active surface vertices in a ribbon fashion improved active volume estimates; and (4) correction with gray matter segmentation removed non-cortical regions from the volumetric measurement of active regions. In conclusion, the new multiple-plane surface-based analysis approaches produce improved measurement of cortical thickness and volume of active brain regions. These results support the use of novel approaches for combined analysis of functional and structural neuroimaging. PMID:19922802

  18. Advanced III/V quantum-structure devices for high performance infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Rehm, Robert; Walther, Martin; Schmitz, Johannes; Rutz, Frank; Fleissner, Joachim; Scheibner, Ralf; Ziegler, Johann

    2009-09-01

    A mature production technology for Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs) and InAs/GaSb superlattice (SL) FPAs has been developed. Dual-band and dual-color QWIP- and SL-imagers are demonstrated for the 3-5 μm and 8-12 μm atmospheric windows in the infrared. The simultaneous, co-located detection of both spectral channels resolves the temporal and spatial registration problems common to existing bispectral IRimagers. The ability for a reliable remote detection of hot CO2 signatures makes tailored dual-color superlattice imagers ideally suited for missile warning systems for airborne platforms.

  19. TIGHT CORRELATIONS BETWEEN MASSIVE GALAXY STRUCTURAL PROPERTIES AND DYNAMICS: THE MASS FUNDAMENTAL PLANE WAS IN PLACE BY z ∼ 2

    SciTech Connect

    Bezanson, Rachel; Van Dokkum, Pieter G.; Leja, Joel; Van de Sande, Jesse; Franx, Marijn; Kriek, Mariska

    2013-12-20

    The fundamental plane (FP) is an empirical relation between the size, surface brightness, and velocity dispersion of early-type galaxies. This relation has been studied extensively for early-type galaxies in the local universe to constrain galaxy formation mechanisms. The evolution of the zero point of this plane has been extended to high redshifts to study the luminosity evolution of massive galaxies, under the assumption of structural homology. In this work, we assess this assumption by replacing surface brightness with stellar mass density and present the evolution of the ''mass FP'' for massive, quiescent galaxies since z ∼ 2. By accounting for stellar populations, we thereby isolate and trace structural and dynamical evolution. Despite the observed dramatic evolution in the sizes and morphologies of massive galaxies since z ∼ 3, we find that quiescent galaxies lie on the mass FP out to z ∼ 2. In contrast with ∼1.4 dex evolution in the luminosity FP, average residuals from the z ∼ 0 mass FP are less than ∼0.15 dex since z ∼ 2. Assuming the Hyde and Bernardi mass FP slope, we find that this minimal offset scales as (1 + z){sup –0.095} {sup ±} {sup 0.043}. This result lends credence to previous studies that derived luminosity evolution from the FP. Therefore, despite their compact sizes and suggestions that massive galaxies are more disk-like at z ∼ 2, the relationship between their dynamics and structural properties are consistent with local early-type galaxies. Finally, we find no strong evidence for a tilt of the mass FP relative to the virial plane, but emphasize the need for full models including selection biases to fully investigate this issue.

  20. Glide-plane symmetry and superconducting gap structure of iron-based superconductors.

    PubMed

    Wang, Y; Berlijn, T; Hirschfeld, P J; Scalapino, D J; Maier, T A

    2015-03-13

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories have proposed that so-called η-pairing states with nonzero total momentum can be realized and possess exotic properties such as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that η pairing is inevitable when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z; however, by explicit calculation, we conclude that the gap function that appears in observable quantities is identical to that found in earlier, 1 Fe per unit cell pseudocrystal momentum calculations. PMID:25815960

  1. Glide-plane symmetry and superconducting gap structure of iron-based superconductors

    DOE PAGESBeta

    Wang, Yan; Berlijn, Tom; Hirschfeld, Peter J.; Scalapino, Douglas J.; Maier, Thomas A.

    2015-03-10

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories propose that so-called η-pairing states with nonzero total momentum can be realized and possess such exotic properties as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z, η pairing is inevitable; however, we conclude from explicit calculation that the gap function appearing in observable quantities is identical to that found in earlier pseudocrystal momentummore » calculations with 1 Fe per unit cell.« less

  2. Glide-plane symmetry and superconducting gap structure of iron-based superconductors

    SciTech Connect

    Wang, Yan; Berlijn, Tom; Hirschfeld, Peter J.; Scalapino, Douglas J.; Maier, Thomas A.

    2015-03-10

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories propose that so-called η-pairing states with nonzero total momentum can be realized and possess such exotic properties as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z, η pairing is inevitable; however, we conclude from explicit calculation that the gap function appearing in observable quantities is identical to that found in earlier pseudocrystal momentum calculations with 1 Fe per unit cell.

  3. Domain structures and correlated out-of-plane and in-plane polarization reorientations in Pb(Zr0.96Ti0.04)O3 single crystal via piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Andreeva, N. V.; Pertsev, N. A.; Andronikova, D. A.; Filimonov, A. V.; Leontiev, N. G.; Leontyev, I. N.; Vakhrushev, S. B.

    2016-09-01

    Pb(Zr1-xTix)O3 single crystal with a low titanium content (x = 4%) was studied by the piezoresponse force microscopy (PFM) and X-ray diffraction (XRD). The XRD studies showed that the crystal faces are orthogonal to the principal cubic axes and confirmed the existence of an intermediate phase between the high-temperature paraelectric (PE) phase and the low-temperature antiferroelectric (AFE) one. A significant temperature hysteresis of phase transitions was observed by the XRD: On heating, the AFE state transforms into the intermediate one at about 373 K and the PE phase appears at 508 K, whereas on cooling the intermediate phase forms at 503 K and persists down to at least 313 K. The PFM investigation was focused on the intermediate phase and involved measurements of both out-of-plane and in-plane electromechanical responses of the (001)-oriented crystal face. The PFM images revealed the presence of polarization patterns switchable by an applied electric field, which confirms the ferroelectric character of the intermediate phase. Importantly, two types of regular domain structures were found, which differ by the spatial orientation of domain walls. The reconstruction of polarization configurations in the observed domain structures showed that one of them is a purely ferroelectric 180° structure with domain walls orthogonal to the crystal surface and parallel to one of the ⟨111⟩ pseudocubic directions. Another one is a ferroelectric-ferroelastic domain structure with the 71° walls parallel to the {101} or {011} crystallographic planes. Remarkably, this domain structure shows correlated out-of-plane and in-plane polarization reorientations after the poling with the aid of the microscope tip.

  4. Functional fatigue behavior of superelastic beta Ti-22Nb-6Zr(at%) alloy for load-bearing biomedical applications.

    PubMed

    Sheremetyev, V; Brailovski, V; Prokoshkin, S; Inaekyan, K; Dubinskiy, S

    2016-01-01

    Ti-22Nb-6Zr (at.%) alloy with different processing-induced microstructures (highly-dislocated partially recovered substructure, polygonized nanosubgrained (NSS) dislocation substructure, and recrystallized structure) was subjected to strain-controlled tension-tension fatigue testing in the 0.2...1.5% strain range (run-out at 10^6 cycles). The NSS alloy obtained after cold-rolling with 0.3 true strain and post-deformation annealing at 600 °C showed the lowest Young's modulus and globally superior fatigue performance due to the involvement of reversible stress-induced martensitic transformation in the deformation process. This NSS structure appears to be suitable for biomedical applications with an extended variation range of loading conditions (orthopedic implants).

  5. Predicting the Influence of Nano-Scale Material Structure on the In-Plane Buckling of Orthotropic Plates

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Odegard, Gregory M.; Nemeth, Michael P.; Frankland, Sarah-Jane V.

    2004-01-01

    A multi-scale analysis of the structural stability of a carbon nanotube-polymer composite material is developed. The influence of intrinsic molecular structure, such as nanotube length, volume fraction, orientation and chemical functionalization, is investigated by assessing the relative change in critical, in-plane buckling loads. The analysis method relies on elastic properties predicted using the hierarchical, constitutive equations developed from the equivalent-continuum modeling technique applied to the buckling analysis of an orthotropic plate. The results indicate that for the specific composite materials considered in this study, a composite with randomly orientated carbon nanotubes consistently provides the highest values of critical buckling load and that for low volume fraction composites, the non-functionalized nanotube material provides an increase in critical buckling stability with respect to the functionalized system.

  6. Mechanical properties and in vivo performance of load-bearing fiber-reinforced composite intramedullary nails with improved torsional strength.

    PubMed

    Moritz, N; Strandberg, N; Zhao, D S; Mattila, R; Paracchini, L; Vallittu, P K; Aro, H T

    2014-12-01

    Fiber-reinforced composites (FRC) could be feasible materials for fracture fixation devices if the mechanical properties of the composites are congruent with the local structural properties of bone. In a recently developed FRC implant, bisphenol A dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) resin was reinforced with unidirectional E-glass fibers. The addition of a braided glass fiber sleeving to the unidirectional fibers increased the torsional strength (99.5MPa) of the FRC implants at the expense of the flexural strength (602.0MPa). The flexural modulus was 15.3GPa. Two types of FRC intramedullary nails were prepared; first type was FRC as such, second type was FRC with a surface layer of bioactive glass (BG) granules. Experimental oblong subtrochanteric defect was created in 14 rabbits. The defect, which reduced the torsional strength of the bones by 66%, was fixed with an FRC intramedullary nail of either type. The contralateral intact femur served as the control. This model simulated surgical stabilization of bone metastasis. After 12 weeks of follow-up, the femurs were harvested and analyzed by torsional testing, micro-CT and hard tissue histology. Healed undisplaced peri-implant fractures were noticed in half of the animals irrespective of the type of FRC implant. Torsional testing showed no significant differences between the implantation groups. The torsional strength of the bones stabilized by either type of FRC implant was 83% of that of the contralateral femurs. In histological analysis, no implant debris and no adverse tissue reactions were observed. While the mechanical properties of the modified FRCs were suboptimal, the FRC intramedullary nails supported the femurs without structural failure, even in the cases of peri-implant fractures. PMID:25222871

  7. Modeling and performance of two types of piston-like out-of-plane motion micromechanical structures

    NASA Astrophysics Data System (ADS)

    Lim, Si-Hyung; Horowitz, Roberto; Majumdar, Arunava

    2006-07-01

    We have modeled and analyzed the performance of two types of piston-like out-of-plane motion micromechanical structures: a conventional microstructure, which has a single bimorph region, and a flip-over-bimaterial (FOB) microstructure, which has two bimorph regions respectively located on the top and bottom sides of the structure. For both structures, simple analytical expressions of their end-point deflections have been established to facilitate parametric studies in sensor or actuator designs. These structures can be used in several applications such as temperature and chemical sensors, or as actuators for micromirrors. The derived analytical deflection predictions are in good agreement with those made using finite element (FE) models. For a micro-opto-mechanical sensor using interconnected FOB microstructures, these analytical and FE predictions agree with the experimental results within about 25%. Discrepancies can be attributed to uncertainties in the material properties of the specimen being tested. Both the analytically derived deflection expressions and the FE models predict that the FOB microstructures are capable of achieving up to two times higher deflection than conventional microstructures that have a single bimorph region. When compared to a cantilever design, a sensor design having interconnected FOB structures has a higher signal-to-noise ratio for the same device footprint. The analytical modeling and performance analysis presented in this paper can be useful to predict the device performance as well as optimize design parameters.

  8. In-plane current induced domain wall nucleation and its stochasticity in perpendicular magnetic anisotropy Hall cross structures

    SciTech Connect

    Sethi, P.; Murapaka, C.; Lim, G. J.; Lew, W. S.

    2015-11-09

    Hall cross structures in magnetic nanowires are commonly used for electrical detection of magnetization reversal in which a domain wall (DW) is conventionally nucleated by a local Oersted field. In this letter, we demonstrate DW nucleation in Co/Ni perpendicular magnetic anisotropy nanowire at the magnetic Hall cross junction. The DWs are nucleated by applying an in-plane pulsed current through the nanowire without the need of a local Oersted field. The change in Hall resistance, detected using anomalous Hall effect, is governed by the magnetic volume switched at the Hall junction, which can be tuned by varying the magnitude of the applied current density and pulse width. The nucleated DWs are driven simultaneously under the spin transfer torque effect when the applied current density is above a threshold. The possibility of multiple DW generation and variation in magnetic volume switched makes nucleation process stochastic in nature. The in-plane current induced stochastic nature of DW generation may find applications in random number generation.

  9. In-plane orientation effects on the electronic structure, stability, and Raman scattering of monolayer graphene on Ir(111)

    NASA Astrophysics Data System (ADS)

    Starodub, Elena; Bostwick, Aaron; Moreschini, Luca; Nie, Shu; Gabaly, Farid El; McCarty, Kevin F.; Rotenberg, Eli

    2011-03-01

    We employ angle-resolved photoemission spectroscopy (ARPES) to investigate the electronic structures of two rotational variants of epitaxial, single-layer graphene on Ir(111). As grown, the more-abundant R0 variant is nearly charge neutral, with strong hybridization between graphene and Ir bands near the Fermi level. The graphene Fermi surface and its replicas exactly coincide with Van Hove singularities in the Ir Fermi surface. Sublattice symmetry breaking introduces a small gap-inducing potential at the Dirac crossing, which is revealed by n doping the graphene using K atoms. The energy gaps between main and replica bands (originating from the moiré interference pattern between graphene and Ir lattices) is shown to be nonuniform along the minizone boundary owing to hybridization with Ir bands. An electronically mediated interaction is proposed to account for the stability of the R0 variant. The variant rotated 30° in plane, R30, is p doped as grown, and K doping reveals no band gap at the Dirac crossing. No replica bands are found in ARPES measurements. Raman spectra from the R30 variant exhibit the characteristic phonon modes of graphene, while R0 spectra are featureless. These results show that the film and substrate interaction changes from chemisorption (R0) to physisorption (R30) with in-plane orientation. Finally, graphene-covered Ir has a work function lower than the clean substrate but higher than graphite.

  10. Determination of three-dimensional structured objects, vascular structures, and imaging geometry from single-plane and biplane projection images

    NASA Astrophysics Data System (ADS)

    Nazareth, Daryl P.

    Three-dimensional (3D) vessel trees can provide useful visual and quantitative information during interventional procedures. To calculate the 3D vasculature and improve these measurements, we have developed methods for the determination of geometric parameters from single-plane and biplane projection images. Our single-plane technique provides an accurate estimation of the magnification and orientation of objects of known dimensions in vessels by comparing measurements in the images with those in simulated images of modeled objects. Our biplane technique calculates the transformation relating the imaging systems (i.e., the rotation matrix R and the translation vector t) and requires only the identification of approximately corresponding vessel regions in the two images. Initial estimates of R and t are refined using an optimization method. The objective function to be minimized is based on the amount of overlap of corresponding vessel regions in the two images. The 3D vasculature is then obtained from the optimal R and t using triangulation. The accuracy of the 3D vasculature calculations may be further improved when a calibration object, such as a stent, is present in the vasculature and the biplane images, if the required user-indicated points in the stent are highly accurate. We have modified the above biplane technique to incorporate information provided by the stent, by including three additional terms in the objective function. These techniques were evaluated using simulated and phantom images. The single-plane technique provided accuracies of 1% in magnification and 2 degrees in orientation. The biplane technique provided accuracies of 1% and 1 degree, respectively, which was reduced to 0.3% and 0.5 degrees in simulations when a calibration object was present. The results of the biplane technique applied to the phantom indicated that inaccuracies in user indication of the calibration object may propagate into the errors in the 3D vessel tree reconstruction

  11. A new approach to plane-sweep overlay: topological structuring and line-segment classification

    USGS Publications Warehouse

    van Roessel, Jan W.

    1991-01-01

    An integrated approach to spatial overlay was developed with the objective of creating a single function that can perform most of the tasks now assigned to discrete functions in current systems. Two important components of this system are a unique method for topological structuring, and a method for attribute propagation and line-segment classification. -Author

  12. Structural Difference in Superconductive and Nonsuperconductive Bi-S Planes within Bi4O4Bi2S4 Blocks.

    PubMed

    Miura, Akira; Mizuguchi, Yoshikazu; Sugawara, Tsuyoshi; Wang, Yongming; Takei, Takahiro; Kumada, Nobuhiro; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Miura, Osuke; Tadanaga, Kiyoharu

    2015-11-01

    The relationship between the structure and superconductivity of Bi4O4S3 powders synthesized by heating under ambient and high pressures was investigated using synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy (TEM) observation. The Bi4O4S3 powders synthesized under ambient pressure exhibited a strong superconductivity (diamagnetic) signal and zero resistivity below ∼4.5 K, while the Bi4O4S3 powder synthesized by the high-pressure method exhibited a low-intensity signal down to 2 K. Further annealing of the latter Bi4O4S3 powder under ambient pressure led to the development of a strong signal and zero resistivity. The crystal structures of all Bi4O4S3 phases consisted of Bi4O4Bi2S4 blocks including a Bi-S layer and anion(s) sandwiched between Bi4O4Bi2S4 blocks, but minor structural differences were detected. A comparison of the structures of the superconductive and nonsuperconductive Bi4O4S3 samples suggested that the superconductive Bi4O4S3 phases had slightly smaller lattice parameters. The average structures of the superconductive Bi4O4S3 phases were characterized by a slightly shorter and less bent Bi-S plane. Raman spectroscopy detected vibration of the S-O bonds, which can be attributed to sandwiched anion(s) such as SO4(2-). TEM observation showed stacking faults in the superconductive Bi4O4S3 phases, which indicated local fluctuation of the average structures. The observed superconductivity of Bi4O4S3 was discussed based on impurity phases, enhanced hybridization of the px and py orbitals of the Bi-S plane within Bi4O4Bi2S4 blocks, local fluctuation of the average structures, compositional deviation related to suspicious anion(s) sandwiched between Bi4O4Bi2S4 blocks, and the possibility of suppression of the charge-density-wave state by enriched carrier concentrations.

  13. Enabling technologies research and development structures. [for National Aerospace Plane Program

    NASA Technical Reports Server (NTRS)

    Davis, John G., Jr.; Murrow, Harold N.

    1989-01-01

    The technology-development areas of most critical importance to the definition of the NASP vehicle's airframe and integrated propulsion systems are discussed with a view to the progress made to date and the prospects for the expansion of a definitive NASP design data base on materials, structures, etc. It is necessary to achieve a very low structural-mass fraction, to withstand 6000 F radiation equilibrium fuselage nosecap temperatures, to manage an extensive active cooling network for both airframe and propulsion system capable of dissipating 10,000 BTU/sq ft-sec thermal fluxes, to maintain effective hot-gas sealing, and to manufacture high temperature effectiveness-retaining control surfaces. An account is given of successes thus far achieved.

  14. Scanning transmission X-ray microscopy study of the stretched magnetic-domain structure of Co/Pt multilayers under an in-plane field

    NASA Astrophysics Data System (ADS)

    Handoko, Djati; Quach, Duy-Truong; Lee, Sang-Hyuk; Shim, Je-Ho; Kim, Dong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Kim, Namdong; Shin, Hyun-Joon

    2015-06-01

    We report our investigation on the magnetic-domain structure of a Co/Pt multilayer with perpendicular magnetic anisotropy under a horizontal in-plane field by using a high-resolution scanning transmission X-ray microscope (STXM) developed at Pohang Accelerator Laboratory. The ruggedshaped striped magnetic-domain structure that was initially formed under a field cycle along the out-of-the plane magnetic easy axis was found to be stretched and elongated along the direction of the horizontal in-plane field. As the in-plane field was strengthened, the striped pattern exhibited an anisotropic domain growth with further stretching and aligning, as well as with a modification of the magnetic-domain's width.

  15. Damage visualization based on local dynamic perturbation: Theory and application to characterization of multi-damage in a plane structure

    NASA Astrophysics Data System (ADS)

    Xu, Hao; Cheng, Li; Su, Zhongqing; Guyader, Jean-Louis

    2013-07-01

    Previously, an inverse damage characterization framework was proposed by quantifying the perturbation to local dynamic equilibrium of a beam-like structure, showing advantages in some aspects over the traditional global vibration-based and local guided-wave-based methods. Residing on the plate theory, this framework was expanded to a two-dimensional domain. Inheriting the attributes of localized canvassing using high-order spatial derivatives this approach has proven effectiveness in quantitatively characterizing damage of small dimension, regardless of its number and type. In addition, the approach requires no benchmarks, baseline signals, global models, additional excitation sources, pre-modal analysis nor prior knowledge on structural boundary. A damage imaging algorithm using the quantified dynamic perturbation was further established, enabling presentation of damage characterization results in an intuitive and prompt manner. Integrating the detection capacities in one- and two-dimensional domains, a hybrid damage visualization strategy was developed, for systems comprising structural components of different types, various geometries and diverse boundary conditions. Two independent de-noising techniques (low-pass wavenumber filtering and adjustment of measurement density), together with a hybrid data fusion algorithm, were proposed as auxiliary means to enhance the robustness of the strategy in noisy measurement conditions. The strategy was applied experimentally to the evaluation of multi-damage in a plane structure comprising beam and plate components, showing satisfactory results.

  16. Compact Test Structure to Measure All Thermophysical Properties for the In-Plane Figure of Merit ZT of Thin Films

    NASA Astrophysics Data System (ADS)

    Moser, Dominik; Mueller, David; Paul, Oliver

    2016-11-01

    This paper reports a versatile thermophysical test structure to measure all material properties contributing to the in-plane thermoelectric figure of merit ZT=S^2Tκ ^{-1} ρ ^{-1} from a single thin film sample of only about 0.5 mm^2. These properties are the Seebeck coefficient S of the sample against aluminum (Al), its thermal conductivity κ , and its resistivity ρ. The thermal membrane-based test structure is produced using standard thin film deposition and structuring processes followed by silicon micromachining. It can be used to characterize thin films deposited at high temperature, such as doped polycrystalline silicon (poly-Si), as well as films deposited at low temperature, e.g., sputtered metals. We present the measurement of all components of the ZT of low-pressure, chemical vapor-deposited n- and p-doped poly-Si thin films in the temperature range from 300 K to 380 K. Values of 1.46 × 10-2 and 0.95 × 10-2 were found at room temperature (RT) for the ZT of n- and p-doped poly-Si films, respectively. Furthermore, the test structure was used to extract ρ and κ of a sputtered aluminum film in the same temperature range. The respective RT values are 48.7 × 10-9 Ω {m} and 154 W m-1 K-1.

  17. Magnetization reversal induced by in-plane current in Ta/CoFeB/MgO structures with perpendicular magnetic easy axis

    SciTech Connect

    Zhang, C.; Yamanouchi, M. Ikeda, S.; Sato, H.; Fukami, S.; Matsukura, F.; Ohno, H.

    2014-05-07

    We investigate in-plane current-induced magnetization reversal under an in-plane magnetic field in Hall bar shaped devices composed of Ta/CoFeB/MgO structures with perpendicular magnetic easy axis. The observed relationship between the directions of current and magnetization switching and Ta thickness dependence of magnetization switching current are accordance with those for magnetization reversal by spin transfer torque originated from the spin Hall effect in the Ta layer.

  18. Mechanics, degradability, bioactivity, in vitro, and in vivo biocompatibility evaluation of poly(amino acid)/hydroxyapatite/calcium sulfate composite for potential load-bearing bone repair.

    PubMed

    Fan, Xiaoxia; Ren, Haohao; Luo, Xiaoman; Wang, Peng; Lv, Guoyu; Yuan, Huipin; Li, Hong; Yan, Yonggang

    2016-03-01

    A ternary composite of poly(amino acid), hydroxyapatite, and calcium sulfate (PAA/HA/CS) was prepared using in situ melting polycondensation method and evaluated in terms of mechanical strengths, in vitro degradability, bioactivity, as well as in vitro and in vivo biocompatibility. The results showed that the ternary composite exhibited a compressive strength of 147 MPa, a bending strength of 121 MPa, a tensile strength of 122 MPa, and a tensile modulus of 4.6 GPa. After immersion in simulated body fluid, the compressive strength of the composite decreased from 147 to 98 MPa for six weeks and the bending strength decreased from 121 to 75 MPa for eight weeks, and both of them kept stable in the following soaking period. The composite could be slowly degraded with 7.27 wt% loss of initial weight after soaking in phosphate buffered solution for three weeks when started to keep stable weight in the following days. The composite was soaked in simulated body fluid solution and the hydroxyapatite layer, as flower-like granules, formed on the surface of the composite samples, showing good bioactivity. Moreover, it was found that the composite could promote proliferation of MG-63 cells, and the cells with normal phenotype extended and spread well on the composite surface. The implantation of the composite into the ulna of sheep confirmed that the composite was biocompatible and osteoconductive in vivo, and offered the PAA/HA/CS composite promising material for load-bearing bone substitutes for clinical application.

  19. Low elastic modulus Ti-Ta alloys for load-bearing permanent implants: enhancing the biodegradation resistance by electrochemical surface engineering.

    PubMed

    Kesteven, Jazmin; Kannan, M Bobby; Walter, Rhys; Khakbaz, Hadis; Choe, Han-Choel

    2015-01-01

    In this study, the in vitro degradation behaviour of titanium-tantalum (Ti-Ta) alloys (10-30 wt.% Ta) was investigated and compared with conventional implant materials, i.e., commercially pure titanium (Cp-Ti) and titanium-aluminium-vanadium (Ti6Al4V) alloy. Among the three Ti-Ta alloys studied, the Ti20Ta (6.3×10(-4) mm/y) exhibited the lowest degradation rate, followed by Ti30Ta (1.2×10(-3) mm/y) and Ti10Ta (1.4×10(-3) mm/y). All the Ti-Ta alloys exhibited lower degradation rate than that of Cp-Ti (1.8×10(-3) mm/y), which suggests that Ta addition to Ti is beneficial. As compared to Ti6Al4V alloy (8.1×10(-4) mm/y), the degradation rate of Ti20Ta alloy was lower by ~22%. However, the Ti30Ta alloy, which has closer elastic modulus to that of natural bone, showed ~48% higher degradation rate than that of Ti6Al4V alloy. Hence, to improve the degradation performance of Ti30Ta alloy, an intermediate thin porous layer was formed electrochemically on the alloy followed by calcium phosphate (CaP) electrodeposition. The coated Ti30Ta alloy (3.8×10(-3) mm/y) showed ~53% lower degradation rate than that of Ti6Al4V alloy. Thus, the study suggests that CaP coated Ti30Ta alloy can be a viable material for load-bearing permanent implants.

  20. Mechanics, degradability, bioactivity, in vitro, and in vivo biocompatibility evaluation of poly(amino acid)/hydroxyapatite/calcium sulfate composite for potential load-bearing bone repair.

    PubMed

    Fan, Xiaoxia; Ren, Haohao; Luo, Xiaoman; Wang, Peng; Lv, Guoyu; Yuan, Huipin; Li, Hong; Yan, Yonggang

    2016-03-01

    A ternary composite of poly(amino acid), hydroxyapatite, and calcium sulfate (PAA/HA/CS) was prepared using in situ melting polycondensation method and evaluated in terms of mechanical strengths, in vitro degradability, bioactivity, as well as in vitro and in vivo biocompatibility. The results showed that the ternary composite exhibited a compressive strength of 147 MPa, a bending strength of 121 MPa, a tensile strength of 122 MPa, and a tensile modulus of 4.6 GPa. After immersion in simulated body fluid, the compressive strength of the composite decreased from 147 to 98 MPa for six weeks and the bending strength decreased from 121 to 75 MPa for eight weeks, and both of them kept stable in the following soaking period. The composite could be slowly degraded with 7.27 wt% loss of initial weight after soaking in phosphate buffered solution for three weeks when started to keep stable weight in the following days. The composite was soaked in simulated body fluid solution and the hydroxyapatite layer, as flower-like granules, formed on the surface of the composite samples, showing good bioactivity. Moreover, it was found that the composite could promote proliferation of MG-63 cells, and the cells with normal phenotype extended and spread well on the composite surface. The implantation of the composite into the ulna of sheep confirmed that the composite was biocompatible and osteoconductive in vivo, and offered the PAA/HA/CS composite promising material for load-bearing bone substitutes for clinical application. PMID:26635202

  1. Improved performance of HgCdTe infrared detector focal plane arrays by modulating light field based on photonic crystal structure

    SciTech Connect

    Liang, Jian; Hu, Weida Ye, Zhenhua; Li, Zhifeng; Chen, Xiaoshuang Lu, Wei; Liao, Lei

    2014-05-14

    An HgCdTe long-wavelength infrared focal plane array photodetector is proposed by modulating light distributions based on the photonic crystal. It is shown that a promising prospect of improving performance is better light harvest and dark current limitation. To optimize the photon field distributions of the HgCdTe-based photonic crystal structure, a numerical method is built by combining the finite-element modeling and the finite-difference time-domain simulation. The optical and electrical characteristics of designed HgCdTe mid-wavelength and long-wavelength photon-trapping infrared detector focal plane arrays are obtained numerically. The results indicate that the photon crystal structure, which is entirely compatible with the large infrared focal plane arrays, can significantly reduce the dark current without degrading the quantum efficiency compared to the regular mesa or planar structure.

  2. Evaluation of the performance correlated defects of metamorphic InGaAs photodetector structures through plane-view EBIC

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-gang; Liu, Ke-hui; Gu, Yi; Zhou, Li; Li, Hsby; Chen, Xing-you; Cao, Yuan-ying; Xi, Su-ping

    2014-03-01

    To evaluate the performance correlated imperfection or defect features of metamorphic InGaAs photodetector structures, a scanning electron microscopy scheme including both plane-view electron beam induced current (EBIC) and secondary electron (SE) images have been used. The abilities, merits and limitations as well as some case-dependent properties of EBIC have been discussed in detail. The devices of similar structures grown on InP or GaAs substrates with quite different lattice mismatch show discriminated defect distribution patterns, prompting their distinct origins, which have been confirmed by cross-sectional transmission electron microscopy observation. Using self-developed image processing software the EBIC features of the samples are statistically analyzed, which validated the qualitative correlation between the EBIC data and device dark current. Fusing of EBIC and SE images has also been attempted to enhance the defect visibility. Results indicate that EBIC is feasible to investigate the effects of defects on the device performance not only in research work, but also for product quality monitor purposes.

  3. Off-easy-plane antiferromagnetic spin canting in coupled FePt/NiO bilayer structure with perpendicular exchange bias

    NASA Astrophysics Data System (ADS)

    Gao, Tenghua; Itokawa, Nobuhide; Wang, Jian; Yu, Youxing; Harumoto, Takashi; Nakamura, Yoshio; Shi, Ji

    2016-08-01

    We report on the investigation of perpendicular exchange bias in FePt (001 ) /NiO (1 ¯1 ¯1 ) orthogonal exchange couple with FePt partially L 10 ordered. From initial magnetization curve measurement and magnetic domain imaging, we find that, for the as-grown bilayer structure, the FePt layer experiences a small-angle magnetization rotation when it is magnetized near to saturation in film normal direction. After field cooling, the bilayer structure shows a significant enhancement of perpendicular magnetic anisotropy, indicating the field mediated coupling between the spins across the FePt/NiO interface. According to Koon's theoretical calculation on the basis of lowest energy ferromagnetic/antiferromagnetic coupling configuration for compensated spins at antiferromagnetic side, we consider slightly slanted Ni spins at the interface off the (1 ¯1 ¯1 ) easy plane can stabilize the spin coupling between FePt and NiO and result in the observed exchange bias in this paper. This consideration was further confirmed by stripe domain width calculation.

  4. Demonstration of large format mid-wavelength infrared focal plane arrays based on superlattice and BIRD detector structures

    NASA Astrophysics Data System (ADS)

    Hill, Cory J.; Soibel, Alexander; Keo, Sam A.; Mumolo, Jason M.; Ting, David Z.; Gunapala, Sarath D.

    2009-11-01

    We have demonstrated the use of bulk antimonide based materials and type-II antimonide based superlattices in the development of large area mid-wavelength infrared (MWIR) focal plane arrays (FPAs). Barrier infrared photodetectors (BIRDs) and superlattice-based infrared photodetectors are expected to outperform traditional III-V MWIR and LWIR imaging technologies and are expected to offer significant advantages over II-VI material based FPAs. We have used molecular beam epitaxy (MBE) technology to grow InAs/GaSb superlattice pin photodiodes and bulk InAsSb structures on GaSb substrates. The coupled quantum well superlattice device offers additional control in wavelength tuning via quantum well sizes and interface composition, while the BIRD structure allows for device fabrication without additional passivation. As a demonstration of the large area imaging capabilities of this technology, we have fabricated mid-wavelength 1024 × 1024 pixels superlattice imaging FPAs and 640 × 512 MWIR arrays based on the BIRD concept. These initial FPA have produced excellent infrared imagery.

  5. Determination of the effect of initial inner-core structure on tropical cyclone intensification and track on a beta plane

    NASA Astrophysics Data System (ADS)

    Chen, Guanghua

    2016-08-01

    The sensitivity of TC intensification and track to the initial inner-core structure on a β plane is investigated using a numerical model. The results show that the vortex with large inner-core winds (CVEX-EXP) experiences an earlier intensification than that with small inner-core winds (CCAVE-EXP), but they have nearly the same intensification rate after spin-up. In the early stage, the convective cells associated with surface heat flux are mainly confined within the inner-core region in CVEX-EXP, whereas the vortex in CCAVE-EXP exhibits a considerably asymmetric structure with most of the convective vortices being initiated to the northeast in the outer-core region due to the β effect. The large inner-core inertial stability in CVEX-EXP can prompt a high efficiency in the conversion from convective heating to kinetic energy. In addition, much stronger straining deformation and PBL imbalance in the inner-core region outside the primary eyewall ensue during the initial development stage in CVEX-EXP than in CCAVE-EXP, which is conducive to the rapid axisymmetrization and early intensification in CVEX-EXP. The TC track in CVEX-EXP sustains a northwestward displacement throughout the integration, whereas the TC in CCAVE-EXP undergoes a northeastward recurvature when the asymmetric structure is dominant. Due to the enhanced asymmetric convection to the northeast of the TC center in CCAVE-EXP, a pair of secondary gyres embedded within the large-scale primary β gyres forms, which modulates the ventilation flow and thus steers the TC to move northeastward.

  6. Multiple support excitations of open-plane frames by a filtered white noise and soil-structure interaction

    NASA Astrophysics Data System (ADS)

    Allam, Mehter M.

    2010-09-01

    Seismic structural design is essentially the estimation of structural response to a forced motion, which may be deterministic or stochastic, imposed on the ground. The assumption that the same ground motion acts at every point of the base of the structure (or at every support) is not always justifiable; particularly in case of very large structures when considerable spatial variability in ground motion can exist over significant distances—example long span bridges. This variability is partly due to the delay in arrival of the excitation at different supports (which is called the wave passage effect) and due to heterogeneity in the ground medium which results in incoherency and local effects. The current study examines the influence of the wave passage effect (in terms of delay in arrival of horizontal ground excitation at different supports and neglecting transmission through the structure) on the response of a few open-plane frame building structures with soil-structure interaction. The ground acceleration has been modeled by a suitably filtered white noise. As a special case, the ground excitation at different supports has also been treated as statistically independent to model the extreme case of incoherence due to local effects and due to modifications to the ground motion resulting from wave reflections and refractions in heterogeneous soil media. The results indicate that, even for relatively short spanned building frames, wave passage effect can be significant. In the absence of soil-structure interaction, it can significantly increase the root mean square (rms) value of the shear in extreme end columns for the stiffer frames but has negligible effect on the flexible frames when total displacements are considered. It is seen that pseudo-static displacements increasingly contribute to the rms value of column shear as the time delay increases both for the stiffer and for the more flexible frames. When soil-structure interaction is considered, wave passage

  7. Liquid crystal-gated-organic field-effect transistors with in-plane drain-source-gate electrode structure.

    PubMed

    Seo, Jooyeok; Nam, Sungho; Jeong, Jaehoon; Lee, Chulyeon; Kim, Hwajeong; Kim, Youngkyoo

    2015-01-14

    We report planar liquid crystal-gated-organic field-effect transistors (LC-g-OFETs) with a simple in-plane drain-source-gate electrode structure, which can be cost-effectively prepared by typical photolithography/etching processes. The LC-g-OFET devices were fabricated by forming the LC layer (4-cyano-4'-pentylbiphenyl, 5CB) on top of the channel layer (poly(3-hexylthiophene), P3HT) that was spin-coated on the patterned indium-tin oxide (ITO)-coated glass substrates. The LC-g-OFET devices showed p-type transistor characteristics, while a current saturation behavior in the output curves was achieved for the 50-150 nm-thick P3HT (channel) layers. A prospective on/off ratio (>1 × 10(3)) was obtained regardless of the P3HT thickness, whereas the resulting hole mobility (0.5-1.1 cm(2)/(V s)) at a linear regime was dependent on the P3HT thickness. The tilted ordering of 5CB at the LC-P3HT interfaces, which is induced by the gate electric field, has been proposed as a core point of working mechanism for the present LC-g-OFETs. PMID:25478816

  8. Growth and Characterization of High Quality a-Plane InGaN/GaN Single Quantum Well Structure Grown by Multibuffer Layer Technique

    NASA Astrophysics Data System (ADS)

    Song, Hooyoung; Soak Kim, Jin; Kim, Eun Kyu; Seo, Yong Gon; Hwang, Sung-Min

    2010-04-01

    Nonpolar (1120) a-plane InGaN/GaN single quantum well (SQW) structure has been grown using a multi buffer layer on a (1102) r-plane sapphire substrate. The effects on the lattice constants of the a-plane GaN template caused by reactor pressure and V/III ratio of the first buffer layer were studied to improve the crystal quality. Under optimum growth conditions, the full widths at half maximum (FWHMs) of (1120) X-ray rocking curves along the c- and m-axis orientations were 430 and 530 arcsec, respectively. The optical characteristics of the nonpolar InGaN SQW determined from excitation-power-dependent photoluminescence and temperature-dependent photoluminescence spectra showed the absence of the quantum-confined Stark effect.

  9. Plane wave density functional theory studies of the structural and the electronic properties of amino acids attached to graphene oxide via peptide bonding

    NASA Astrophysics Data System (ADS)

    Min, Byeong June; Jeong, Hae Kyung; Lee, ChangWoo

    2015-08-01

    We studied via plane wave pseudopotential total-energy calculations within the local spin density approximation (LSDA) the electronic and the structural properties of amino acids (alanine, glycine, and histidine) attached to graphene oxide (GO) by peptide bonding. The HOMO-LUMO gap, the Hirshfeld charges, and the equilibrium geometrical structures exhibit distinctive variations that depend on the species of the attached amino acid. The GO-amino acid system appears to be a good candidate for a biosensor.

  10. System and method of designing a load bearing layer that interfaces to a structural pass-through of an inflatable vessel

    NASA Technical Reports Server (NTRS)

    Spexarth, Gary R. (Inventor)

    2010-01-01

    A method for determining a design of an inflatable module including a rigid member disposed in a restraint layer, wherein the restraint layer includes orthogonal straps, includes modeling a strap adjacent to the rigid member and a strap connected to the rigid member. The adjacent strap and the member strap extend in a first direction. The method further includes selecting a first length of the member strap such that the adjacent strap carries load before the member strap during pressurization of the inflatable module, modeling tensions in the member strap with the first length and the adjacent strap during pressurization of the inflatable model, and outputting the modeled tensions in the member strap with the first length and the adjacent strap. An inflatable module includes a member strap having a length such that an adjacent strap carries load before the member strap during pressurization of the inflatable module.

  11. Fermions on the low-buckled honey-comb structured lattice plane and classical Casimir-Polder force

    NASA Astrophysics Data System (ADS)

    Goswami, Partha

    2016-05-01

    We start with the well-known expression for the vacuum polarization and suitably modify it for 2+1-dimensional spin-orbit coupled (SOC) fermions on the low-buckled honey-comb structured lattice plane described by the low-energy Liu-Yao-Feng-Ezawa (LYFE) model Hamiltonian involving the Dirac matrices in the chiral representation obeying the Clifford algebra. The silicene and germanene fit this description suitably. They have the Dirac cones similar to those of graphene and SOC is much stronger. The system could be normal or ferromagnetic in nature. The silicene turns into the latter type if there is exchange field arising due to the proximity coupling to a ferromagnet (FM) such as depositing Fe atoms to the silicene surface. For the silicene, we find that the many-body effects considerably change the bare Coulomb potential by way of the dependence of the Coulomb propagator on the real-spin, iso-spin and the potential due to an electric field applied perpendicular to the silicene plane. The computation aspect of the Casimir-Polder force (CPF) needs to be investigated in this paper. An important quantity in this process is the dielectric response function (DRF) of the material. The plasmon branch was obtained by finding the zeros of DRF in the long-wavelength limit. This leads to the plasmon frequencies. We find that the collective charge excitations at zero doping, i.e., intrinsic plasmons, in this system, are absent in the Dirac limit. The valley-spin-split intrinsic plasmons, however, come into being in the case of the massive Dirac particles with characteristic frequency close to 10 THz. Our scheme to calculate the Casimir-Polder interaction (CPI) of a micro-particle with a sheet involves replacing the dielectric constant of the sample in the CPI expression obtained on the basis of the Lifshitz theory by the static DRF obtained using the expressions for the polarization function we started with. Though the approach replaces a macroscopic constant by a microscopic

  12. THE CANADA-FRANCE ECLIPTIC PLANE SURVEY-FULL DATA RELEASE: THE ORBITAL STRUCTURE OF THE KUIPER BELT

    SciTech Connect

    Petit, J.-M.; Rousselot, P.; Mousis, O.; Kavelaars, J. J.; Gladman, B. J.; Jones, R. L.; Van Laerhoven, C.; Parker, J. Wm.; Bieryla, A.; Nicholson, P.; Mars, G.; Marsden, B.; Ashby, M. L. N.; Taylor, M.; Bernabeu, G.; Benavidez, P.; Campo Bagatin, A.

    2011-10-15

    We report the orbital distribution of the trans-Neptunian objects (TNOs) discovered during the Canada-France Ecliptic Plane Survey (CFEPS), whose discovery phase ran from early 2003 until early 2007. The follow-up observations started just after the first discoveries and extended until late 2009. We obtained characterized observations of 321 deg{sup 2} of sky to depths in the range g {approx} 23.5-24.4 AB mag. We provide a database of 169 TNOs with high-precision dynamical classification and known discovery efficiency. Using this database, we find that the classical belt is a complex region with sub-structures that go beyond the usual splitting of inner (interior to 3:2 mean-motion resonance [MMR]), main (between 3:2 and 2:1 MMR), and outer (exterior to 2:1 MMR). The main classical belt (a = 40-47 AU) needs to be modeled with at least three components: the 'hot' component with a wide inclination distribution and two 'cold' components (stirred and kernel) with much narrower inclination distributions. The hot component must have a significantly shallower absolute magnitude (H{sub g} ) distribution than the other two components. With 95% confidence, there are 8000{sup +1800}{sub -1600} objects in the main belt with H{sub g} {<=} 8.0, of which 50% are from the hot component, 40% from the stirred component, and 10% from the kernel; the hot component's fraction drops rapidly with increasing H{sub g} . Because of this, the apparent population fractions depend on the depth and ecliptic latitude of a trans-Neptunian survey. The stirred and kernel components are limited to only a portion of the main belt, while we find that the hot component is consistent with a smooth extension throughout the inner, main, and outer regions of the classical belt; in fact, the inner and outer belts are consistent with containing only hot-component objects. The H{sub g} {<=} 8.0 TNO population estimates are 400 for the inner belt and 10,000 for the outer belt to within a factor of two (95

  13. Axial Plane Optical Microscopy

    PubMed Central

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-01-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues. PMID:25434770

  14. Axial Plane Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-12-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues.

  15. Futurepath: The Story of Research and Technology at NASA Lewis Research Center. Structures for Flight Propulsion, ARC Sprayed Monotape, National Aero-Space Plane

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The story of research and technology at NASA Lewis Research Center's Structures Division is presented. The job and designs of the Structures Division needed for flight propulsion is described including structural mechanics, structural dynamics, fatigue, and fracture. The video briefly explains why properties of metals used in structural mechanics need to be tested. Examples of tests and simulations used in structural dynamics (bodies in motion) are briefly described. Destructive and non-destructive fatigue/fracture analysis is also described. The arc sprayed monotape (a composite material) is explained, as are the programs in which monotape plays a roll. Finally, the National Aero-Space Plane (NASP or x-30) is introduced, including the material development and metal matrix as well as how NASP will reduce costs for NASA.

  16. Xenoimplantation of an Extracellular-Matrix-Derived, Biphasic, Cell-Scaffold Construct for Repairing a Large Femoral-Head High-Load-Bearing Osteochondral Defect in a Canine Model

    PubMed Central

    Qiang, Yang; Yanhong, Zhao; Jiang, Peng; Shibi, Lu; Quanyi, Guo; Xinlong, Ma; Qun, Xia; Baoshan, Xu; Bin, Zhao; Aiyuan, Wang; Li, Zhang; Wengjing, Xu; Chao, Zeng

    2014-01-01

    This study was aimed to develop an ECM-derived biphasic scaffold and to investigate its regeneration potential loaded with BM-MSCs in repair of large, high-load-bearing osteochondral defects of the canine femoral head. The scaffolds were fabricated using cartilage and bone ECM as a cartilage and bone layer, respectively. Osteochondral constructs were fabricated using induced BM-MSCs and the scaffold. Osteochondral defects (11 mm diameter × 10 mm depth) were created on femoral heads of canine and treated with the constructs. The repaired tissue was evaluated for gross morphology, radiography, histological, biomechanics at 3 and 6 months after implantation. Radiography revealed that femoral heads slightly collapsed at 3 months and severely collapsed at 6 months. Histology revealed that some defects in femoral heads were repaired, but with fibrous tissue or fibrocartilage, and femoral heads with different degrees of collapse. The bone volume fraction was lower for subchondral bone than normal femoral bone at 3 and 6 months. Rigidity was lower in repaired subchondral bone than normal femoral bone at 6 months. The ECM-derived, biphasic scaffold combined with induced BM-MSCs did not successfully repair large, high-load-bearing osteochondral defects of the canine femoral head. However, the experience can help improve the technique of scaffold fabrication and vascularization. PMID:24737955

  17. Bandpass filters based on planar metal-dielectric structures in the E-plane of a rectangular waveguide (Review)

    NASA Astrophysics Data System (ADS)

    Gololobov, V. P.; Omelianenko, M. Iu.

    1987-01-01

    The paper surveys the literature and some original results on the development of low-insertion-loss E-plane filters for microwave integrated circuits. Emphasis is placed on the design and fabrication of inductive-strip bandpass filters in rectangular and partially filled waveguides. The possibility of improving the performance of these filters in the multilayer planar realization is demonstrated theoretically. Experimental results agree satisfactorily with calculations.

  18. Continuum dynamics of the formation, migration and dissociation of self-locked dislocation structures on parallel slip planes

    NASA Astrophysics Data System (ADS)

    Zhu, Yichao; Niu, Xiaohua; Xiang, Yang

    2016-11-01

    In continuum models of dislocations, proper formulations of short-range elastic interactions of dislocations are crucial for capturing various types of dislocation patterns formed in crystalline materials. In this article, the continuum dynamics of straight dislocations distributed on two parallel slip planes is modelled through upscaling the underlying discrete dislocation dynamics. Two continuum velocity field quantities are introduced to facilitate the discrete-to-continuum transition. The first one is the local migration velocity of dislocation ensembles which is found fully independent of the short-range dislocation correlations. The second one is the decoupling velocity of dislocation pairs controlled by a threshold stress value, which is proposed to be the effective flow stress for single slip systems. Compared to the almost ubiquitously adopted Taylor relationship, the derived flow stress formula exhibits two features that are more consistent with the underlying discrete dislocation dynamics: (i) the flow stress increases with the in-plane component of the dislocation density only up to a certain value, hence the derived formula admits a minimum inter-dislocation distance within slip planes; (ii) the flow stress smoothly transits to zero when all dislocations become geometrically necessary dislocations. A regime under which inhomogeneities in dislocation density grow is identified, and is further validated through comparison with discrete dislocation dynamical simulation results. Based on the findings in this article and in our previous works, a general strategy for incorporating short-range dislocation correlations into continuum models of dislocations is proposed.

  19. In-plane magnetic-field effect on transport properties of the chiral edge state in a quasi-three-dimensional quantum well structure

    SciTech Connect

    Zhang, B.; Brooks, J.; Wang, Z.; Simmons, J.; Reno, J.; Lumpkin, N.; OBrien, J.; Clark, R.

    1999-09-01

    The transport properties of a quasi-three-dimensional, 200-layer quantum-well structure are investigated at integer filling in the quantum Hall state, concomitant with the chiral edge state condition. We find that the transverse magnetoresistance R{sub xx}, the Hall resistance R{sub xy}, and the vertical resistance R{sub zz} all follow a similar behavior with {ital both} temperature and in-plane magnetic field. A general characteristic of the influence of increasing in-plane field B{sub in} is that the quantization condition first improves, but above a critical value B{sub in}{sup C}, the quantization is systematically removed. We consider the interplay of the chiral edge state transport and the bulk (quantum Hall) transport properties. This mechanism may arise from the competition of the cyclotron energy with the superlattice band-structure energies. A comparison of the results with existing theories of the chiral edge state transport with in-plane field is also discussed. {copyright} {ital 1999} {ital The American Physical Society}

  20. Magnon-driven longitudinal spin Seebeck effect in F | N and N | F | N structures: Role of asymmetric in-plane magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Chotorlishvili, L.; Toklikishvili, Z.; Etesami, S. R.; Dugaev, V. K.; Barnaś, J.; Berakdar, J.

    2015-12-01

    The influence of an asymmetric in-plane magnetic anisotropy Kx ≠Ky on the thermally activated spin current is studied theoretically for two different systems: (i) the F | N system consisting of a ferromagnetic insulator (F) in a direct contact with a nonmagnetic metal (N) and (ii) the sandwich structure N | F | N consisting of a ferromagnetic insulating part sandwiched between two nonmagnetic metals. It is shown that when the difference between the temperatures of the two nonmagnetic metals in a N | F | N structure is not large, the spin pumping currents from the magnetic part to the nonmagnetic ones are equal in amplitude and have opposite directions, so only the spin torque current contributes to the total spin current. The spin current flows then from the nonmagnetic metal with the higher temperature to the nonmagnetic metal having a lower temperature. Its amplitude varies linearly with the difference in temperatures. In addition, we have found that if the magnetic anisotropy is in the layer plane, then the spin current increases with the magnon temperature, while in the case of an out-of-plane magnetic anisotropy the spin current decreases when the magnon temperature enhances. Enlarging the difference between the temperatures of the nonmagnetic metals, the linear response becomes important, as confirmed by analytical expressions inferred from the Fokker-Planck approach and by the results obtained upon a full numerical integration of the stochastic Landau-Lifshitz-Gilbert equation.

  1. Prediction of fatigue crack growth kinetics in the plane structural elements of aircraft in the biaxial stress state

    NASA Astrophysics Data System (ADS)

    Shanyavskij, A. A.; Karaev, K. Z.; Grigor'ev, V. M.; Koronov, M. Z.; Orlov, E. F.

    1991-07-01

    The kinetics of fatigue crack growth in the case of a complex stress state is investigated with particular reference to D16T aluminum alloy. By using simulation models in the form of plane cruciform specimens, the characteristics of fatigue crack growth are investigated under conditions of uniaxial and biaxial tension-compression, with the ratio of the main stresses varying from -1 to 1.5. An algorithm is developed which makes it possible to predict the kinetics of fatigue crack growth and the equivalent stress level under conditions of multiparametric loading.

  2. Development of a fatigue-life methodology for composite structures subjected to out-of-plane load components

    NASA Technical Reports Server (NTRS)

    Sumich, Mark; Kedward, Keith T.

    1991-01-01

    The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuration which used rotor blades primarily constructed of laminated carbon fiber. Delamination of the main spar during ground testing demonstrated that significant interlaminar stresses were produced. Analysis confirmed the presence of out-of-plane load components. The wear out (residual strength) methodology and the requirements for its implementation are discussed.

  3. Effects of electron irradiation on the ferroelectric 180 deg. in-plane nanostripe domain structure in a thin film prepared from a bulk single crystal of BaTiO{sub 3} by focused ion beam

    SciTech Connect

    Matsumoto, Takao; Okamoto, Masakuni

    2011-01-01

    Effects of electron irradiation on the ferroelectric 180 deg. in-plane nanostripe domain structure in a thin film prepared from a bulk single crystal of BaTiO{sub 3} by focused ion beam were studied. The domain structure transformed into a characteristic 90 deg. in-plane nanostripe domain structure under intense electron irradiation. In particular, an unconventional triangular 90 deg. in-plane nanostripe domain structure was observed. Polarization analysis suggests the existence of an incomplete or half tetradomain vortex at the boundary of the triangular domain structure. Together with the help of phase-field simulations using time-dependent Ginzburg-Landau equations, it is suggested that such a domain structure is created by an anisotropic in-plane electric field, which is plausibly induced by an anisotropic interaction of the incident electron beam with the ferroelectric material.

  4. Structural properties of Al-rich AlInN grown on c-plane GaN substrate by metal-organic chemical vapor deposition

    PubMed Central

    2014-01-01

    The attractive prospect for AlInN/GaN-based devices for high electron mobility transistors with advanced structure relies on high-quality AlInN epilayer. In this work, we demonstrate the growth of high-quality Al-rich AlInN films deposited on c-plane GaN substrate by metal-organic chemical vapor deposition. X-ray diffraction, scanning electron microscopy, and scanning transmission electron microscopy show that the films lattice-matched with GaN can have a very smooth surface with good crystallinity and uniform distribution of Al and In in AlInN. PMID:25489282

  5. CMOS correlated-double-sampling and hold structure based on novel dynamic source-follower for large format infrared focal-plane-array

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi; Yuan, Xianghui; Huang, Youshu

    2003-07-01

    In this paper, a CMOS correlated double sampling and hold (CDSH) structure based on novel dynamic source follower for large format infrared focal-plane array (IRFPA) is proposed. The primary noise (fixed-pattern noise (FPN) and KTC reset noise, etc) of the CMOS image sensor is reduced, through the improved CDSH structure based on the novel dynamic source follower, and all pixels in the selected row can start integrating simultaneously; the readout process happens in the next row selection time, which can increase the frame frequency, and the output waveform is boxcar, which is easy-to-realize analog/digital conversion. SPICE simulation results have shown that the proposed improved CDSH structure can achieve the advantages of simple driving signal, large dynamic range in large format IRFPA with low power consumption.

  6. Numerical study on surface plasmon polariton behaviors in periodic metal-dielectric structures using a plane-wave-assisted boundary integral-equation method.

    PubMed

    Kiang, Yean-Woei; Wang, Jyh-Yang; Yang, C C

    2007-07-01

    A novel hybrid technique based on the boundary integral-equation method is proposed for studying the surface plasmon polariton behaviors in two-dimensional periodic structures. Considering the periodicity property of the problem, we use the plane-wave expansion concept and the periodic boundary condition instead of using the periodic Green's function. The diffraction efficiency can then be readily calculated once the equivalent electric and magnetic currents are solved that avoids invoking the numerical calculation of the radiation integral. The numerical validity is verified with the cases of highly conducting materials and practical metals. Numerical convergence can be easily achieved even in the case of a large incident angle as 80o. Based on the numerical scheme, a metal-dielectric wavy structure is designed for enhancing the transmittance of optical signal through the structure. The excitation of the coupled surface plasmon polaritons for the high transmission is demonstrated.

  7. Anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using double AlN buffer layers.

    PubMed

    Zhao, Guijuan; Wang, Lianshan; Yang, Shaoyan; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Wang, Zhanguo

    2016-02-10

    We report the anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11-22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1-100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting.

  8. Anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using double AlN buffer layers

    PubMed Central

    Zhao, Guijuan; Wang, Lianshan; Yang, Shaoyan; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Wang, Zhanguo

    2016-01-01

    We report the anisotropic structural and optical properties of semi-polar (11–22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11–22) GaN, and significantly reduce the density of stacking faults and dislocations. The high resolution x-ray diffraction measurement revealed that the in-plane anisotropic structural characteristics of GaN layer are azimuthal dependent. Transmission electron microscopy analysis showed that the majority of dislocations in the GaN epitaxial layer grown on m-sapphire are the mixed-type and the orientation of GaN layer was rotated 58.4° against the substrate. The room temperature photoluminescence (PL) spectra showed the PL intensity and wavelength have polarization dependence along parallel and perpendicular to the [1–100] axis (polarization degrees ~ 0.63). The realization of a high polarization semi-polar GaN would be useful to achieve III-nitride based lighting emission device for displays and backlighting. PMID:26861595

  9. Molecular Crowding of Collagen: A Pathway to Produce Highly-Organized Collagenous Structures

    PubMed Central

    Saeidi, Nima; Karmelek, Kathryn N.; Paten, Jeffrey. A; Zareian, Ramin; DiMasi, Elaine

    2013-01-01

    Collagen in vertebrate animals is often arranged in alternating lamellae or in bundles of aligned fibrils which are designed to withstand in vivo mechanical loads. The formation of these organized structures is thought to result from a complex, large-area integration of individual cell motion and locally-controlled synthesis of fibrillar arrays via cell-surface fibripositors (direct matrix printing). The difficulty of reproducing such a process in vitro has prevented tissue engineers from constructing clinically useful load-bearing connective tissue directly from collagen. However, we and others have taken the view that long-range organizational information is potentially encoded into the structure of the collagen molecule itself, allowing the control of fibril organization to extend far from cell (or bounding) surfaces. We here demonstrate a simple, fast, cell-free method capable of producing highly-organized, anistropic collagen fibrillar lamellae de novo which persist over relatively long-distances (tens to hundreds of microns). Our approach to nanoscale organizational control takes advantage of the intrinsic physiochemical properties of collagen molecules by inducing collagen association through molecular crowding and geometric confinement. To mimic biological tissues which comprise planar, aligned collagen lamellae (e.g. cornea, lamellar bone or annulus fibrosus), type I collagen was confined to a thin, planar geometry, concentrated through molecular crowding and polymerized. The resulting fibrillar lamellae show a striking resemblance to native load-bearing lamellae in that the fibrils are small, generally aligned in the plane of the confining space and change direction en masse throughout the thickness of the construct. The process of organizational control is consistent with embryonic development where the bounded planar cell sheets produced by fibroblasts suggest a similar confinement/concentration strategy. Such a simple approach to nanoscale

  10. Molecular crowding of collagen: a pathway to produce highly-organized collagenous structures.

    PubMed

    Saeidi, Nima; Karmelek, Kathryn P; Paten, Jeffrey A; Zareian, Ramin; DiMasi, Elaine; Ruberti, Jeffrey W

    2012-10-01

    Collagen in vertebrate animals is often arranged in alternating lamellae or in bundles of aligned fibrils which are designed to withstand in vivo mechanical loads. The formation of these organized structures is thought to result from a complex, large-area integration of individual cell motion and locally-controlled synthesis of fibrillar arrays via cell-surface fibripositors (direct matrix printing). The difficulty of reproducing such a process in vitro has prevented tissue engineers from constructing clinically useful load-bearing connective tissue directly from collagen. However, we and others have taken the view that long-range organizational information is potentially encoded into the structure of the collagen molecule itself, allowing the control of fibril organization to extend far from cell (or bounding) surfaces. We here demonstrate a simple, fast, cell-free method capable of producing highly-organized, anistropic collagen fibrillar lamellae de novo which persist over relatively long-distances (tens to hundreds of microns). Our approach to nanoscale organizational control takes advantage of the intrinsic physiochemical properties of collagen molecules by inducing collagen association through molecular crowding and geometric confinement. To mimic biological tissues which comprise planar, aligned collagen lamellae (e.g. cornea, lamellar bone or annulus fibrosus), type I collagen was confined to a thin, planar geometry, concentrated through molecular crowding and polymerized. The resulting fibrillar lamellae show a striking resemblance to native load-bearing lamellae in that the fibrils are small, generally aligned in the plane of the confining space and change direction en masse throughout the thickness of the construct. The process of organizational control is consistent with embryonic development where the bounded planar cell sheets produced by fibroblasts suggest a similar confinement/concentration strategy. Such a simple approach to nanoscale

  11. KrF resists for implant layers patterning extreme high-aspect ratio structures with a double focal plane exposure technique

    NASA Astrophysics Data System (ADS)

    Rafaelli, Giorgio; Ferri, Fabio; Volpi, Stefano; Hong, Chisun

    2012-03-01

    The design rules for advanced image sensor applications are requiring continuous CD shrinkage, and increasing aspect ratios which resulting in major challenges associated with using KrF technology. For the implant photo layers in particular, the need to block high-energy boron implants (well above 2 MeV) with extremely localized implant profiles requires an aspect ratio of deep well structures greater than 10:1. Other desirable attributes of a good photoresist for such demanding applications are high transparency, a steep wall profile consistent throughout the entire film, good adhesion with no structure collapse, and a wide process window. In this paper, we will discuss the role of a chemically amplified, ESCAP-type of resist in meeting these design criteria using a double focal plane exposure technique.

  12. THE CANADA-FRANCE ECLIPTIC PLANE SURVEY-L3 DATA RELEASE: THE ORBITAL STRUCTURE OF THE KUIPER BELT

    SciTech Connect

    Kavelaars, J. J.; Jones, R. L.; Murray, I.; Gladman, B. J.; Petit, J.-M.; Van Laerhoven, C.; Parker, Joel Wm.; Bieryla, A.; Nicholson, P.; Margot, J. L.; Rousselot, P.; Mousis, O.; Scholl, H.; Marsden, B.; Benavidez, P.; Campo Bagatin, A.; Doressoundiram, A.; Veillet, C.

    2009-06-15

    We report the orbital distribution of the trans-Neptunian comets discovered during the first discovery year of the Canada-France Ecliptic Plane Survey (CFEPS). CFEPS is a Kuiper Belt object survey based on observations acquired by the Very Wide component of the Canada-France-Hawaii Telescope Legacy Survey (LS-VW). The first year's detections consist of 73 Kuiper Belt objects, 55 of which have now been tracked for three years or more, providing precise orbits. Although this sample size is small compared to the world-wide inventory, because we have an absolutely calibrated and extremely well-characterized survey (with known pointing history) we are able to de-bias our observed population and make unbiased statements about the intrinsic orbital distribution of the Kuiper Belt. By applying the (publically available) CFEPS Survey Simulator to models of the true orbital distribution and comparing the resulting simulated detections to the actual detections made by the survey, we are able to rule out several hypothesized Kuiper Belt object orbit distributions. We find that the main classical belt's so-called 'cold' component is confined in semimajor axis (a) and eccentricity (e) compared to the more extended 'hot' component; the cold component is confined to lower e and does not stretch all the way out to the 2:1 resonance but rather depletes quickly beyond a = 45 AU. For the cold main classical belt population we find a robust population estimate of N(H{sub g} < 10) = 50 {+-} 5 x 10{sup 3} and find that the hot component of the main classical belt represents {approx}60% of the total population. The inner classical belt (sunward of the 3:2 mean-motion resonance) has a population of roughly 2000 trans-Neptunian objects with absolute magnitudes H{sub g} < 10, and may not share the inclination distribution of the main classical belt. We also find that the plutino population lacks a cold low-inclination component, and so, the population is somewhat larger than recent estimates

  13. Atomic-scale investigation of structural defects in GaN layer on c-plane sapphire substrate during initial growth stage

    NASA Astrophysics Data System (ADS)

    Matsubara, Tohoru; Sugimoto, Kohei; Okada, Narihito; Tadatomo, Kazuyuki

    2016-04-01

    Structural defects in the initial growth stages of GaN on sapphire, including stacking faults (SFs), threading dislocations (TDs), and mosaic structure containing grain boundaries, are investigated at the atomic scale. Individual grains in the as-deposited low temperature-GaN buffer layer are found to have twists correlated with those of the adjacent grains. These grains have little similarity on the stacking sequences, and the atomic arrangement on each side of the grain boundaries may be rearranged by annealing to achieve higher similarity in the stacking sequence. The TD identified as a-type at the top of the SFs-rich interfacial region is thought to originate from Frank partial dislocations. The Frank partial dislocation produces a distorted wurtzite-type structure. At the intermediate region of the basal-plane stacking fault between Frank and Shockley partial dislocations, the TD relieves the distortion in the wurtzite-type structure. In the TD, the wurtzite structure slips relative to the surrounding wurtzite.

  14. Effect of Structural Relaxation on the In-Plane Electrical Resistance of Oxygen-Underdoped ReBaCuO (Re = Y, Ho) Single Crystals

    NASA Astrophysics Data System (ADS)

    Vovk, Ruslan V.; Vovk, Nikolaj R.; Dobrovolskiy, Oleksandr V.

    2014-05-01

    The effect of jumpwise temperature variation and room-temperature storing on the basal-plane electrical resistivity of underdoped ReBaCuO (Re = Y, Ho) single crystals is investigated. Reducing the oxygen content has been revealed to lead to the phase segregation accompanied by both, labile component diffusion and structural relaxation in the sample volume. Room-temperature storing of single crystals with different oxygen hypostoichiometries leads to a substantial widening of the rectilinear segment in in conjunction with a narrowing of the temperature range of existence of the pseudogap state. It is established that the excess conductivity obeys an exponential law in a broad temperature range, while the pseudogap's temperature dependence is described satisfactory in the framework of the BCS-BEC crossover theory. Substituting yttrium with holmium essentially effects the charge distribution and the effective interaction in CuO planes, thereby stimulating disordering processes in the oxygen subsystem. This is accompanied by a notable shift of the temperature zones corresponding to transitions of the metal-insulator type and to the regime of manifestation of the pseudogap anomaly.

  15. Structure of Sm-Co/Fe-Co multilayer films with in-plane magnetic anisotropies prepared on MgO(110) single-crystal substrates

    NASA Astrophysics Data System (ADS)

    Ohtake, Mitsuru; Hotta, Yusuke; Yamada, Makoto; Suzuki, Ataru; Futamoto, Masaaki; Kirino, Fumiyoshi; Inaba, Nobuyuki

    2016-02-01

    Sm17Co83/Fe65Co35 (at. %) multilayer films are prepared on MgO(110) substrates at 500 °C by ultra-high vacuum molecular beam epitaxy. The film crystallographic properties during formation are investigated by in-situ reflection high-energy electron diffraction. The 1st Fe-Co layer epitaxially grows on the substrate with two variants whose orientations are rotated around the film normal by 180° each other. The 1st Sm-Co layer formed on the 1st Fe-Co layer involves a small volume of amorphous phase in addition to epitaxial (11bar00)) crystal of RT5 structure with the c-axis lying in the film plane. The crystallographic quality of 2nd Fe-Co layer is inferior to that of 1st Fe-Co layer. The 2nd Sm-Co layer is composed of polycrystal and amorphous phases. The crystallographic properties of Sm-Co and Fe-Co layers are delicately influenced by those of lower layers. The Sm-Co/Fe-Co multilayer films involving Sm-Co(11bar00)RT5 epitaxial crystal show in-plane uniaxial magnetic anisotropies reflecting the magnetocrystalline anisotropy of SmCo5 crystal. The coercivity increases with increasing the volume of Sm-Co(11bar00)RT5 crystal.

  16. Out-of-plane (SH) soil-structure interaction: a shear wall with rigid and flexible ring foundation

    NASA Astrophysics Data System (ADS)

    Le, Thang; Lee, Vincent W.; Luo, Hao

    2016-02-01

    Soil-structure interaction (SSI) of a building and shear wall above a foundation in an elastic half-space has long been an important research subject for earthquake engineers and strong-motion seismologists. Numerous papers have been published since the early 1970s; however, very few of these papers have analytic closed-form solutions available. The soil-structure interaction problem is one of the most classic problems connecting the two disciplines of earthquake engineering and civil engineering. The interaction effect represents the mechanism of energy transfer and dissipation among the elements of the dynamic system, namely the soil subgrade, foundation, and superstructure. This interaction effect is important across many structure, foundation, and subgrade types but is most pronounced when a rigid superstructure is founded on a relatively soft lower foundation and subgrade. This effect may only be ignored when the subgrade is much harder than a flexible superstructure: for instance a flexible moment frame superstructure founded on a thin compacted soil layer on top of very stiff bedrock below. This paper will study the interaction effect of the subgrade and the superstructure. The analytical solution of the interaction of a shear wall, flexible-rigid foundation, and an elastic half-space is derived for incident SH waves with various angles of incidence. It found that the flexible ring (soft layer) cannot be used as an isolation mechanism to decouple a superstructure from its substructure resting on a shaking half-space.

  17. Rayleigh-wave phase-velocity maps and three-dimensional shear velocity structure of the western US from local non-plane surface wave tomography

    NASA Astrophysics Data System (ADS)

    Pollitz, F. F.; Snoke, J. Arthur

    2010-03-01

    We utilize two-and-three-quarter years of vertical-component recordings made by the Transportable Array (TA) component of Earthscope to constrain three-dimensional (3-D) seismic shear wave velocity structure in the upper 200 km of the western United States. Single-taper spectral estimation is used to compile measurements of complex spectral amplitudes from 44317 seismograms generated by 123 teleseismic events. In the first step employed to determine the Rayleigh-wave phase-velocity structure, we implement a new tomographic method, which is simpler and more robust than scattering-based methods (e.g. multi-plane surface wave tomography). The TA is effectively implemented as a large number of local arrays by defining a horizontal Gaussian smoothing distance that weights observations near a given target point. The complex spectral-amplitude measurements are interpreted with the spherical Helmholtz equation using local observations about a succession of target points, resulting in Rayleigh-wave phase-velocity maps at periods over the range of 18-125 s. The derived maps depend on the form of local fits to the Helmholtz equation, which generally involve the non-plane-wave solutions of Friederich et al. In a second step, the phase-velocity maps are used to derive 3-D shear velocity structure. The 3-D velocity images confirm details witnessed in prior body-wave and surface-wave studies and reveal new structures, including a deep (>100 km deep) high-velocity lineament, of width ~200 km, stretching from the southern Great Valley to northern Utah that may be a relic of plate subduction or, alternatively, either a remnant of the Mojave Precambrian Province or a mantle downwelling. Mantle seismic velocity is highly correlated with heat flow, Holocene volcanism, elastic plate thickness and seismicity. This suggests that shallow mantle structure provides the heat source for associated magmatism, as well as thinning of the thermal lithosphere, leading to relatively high stress

  18. Atomic structure characterization of stacking faults on the { 1 1 ¯00 } plane in α-alumina by scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Tochigi, Eita; Findlay, Scott D.; Okunishi, Eiji; Mizoguchi, Teruyasu; Nakamura, Atsutomo; Shibata, Naoya; Ikuhara, Yuichi

    2016-08-01

    The structure of a b =<1 1 ¯00 > dislocation formed in the { 1 1 ¯00 } /<112 ¯0> 2° low-angle grain boundary of alumina was observed by scanning transmission electron microscopy (STEM). It was found that the <1 1 ¯00 > dislocation dissociate-s into 1/3<1 1 ¯00 > partial-dislocation triplets with two stacking faults on the { 1 1 ¯00 } plane. The atomic structure of the { 1 1 ¯00 } stacking faults was characterized by annular bright field STEM (ABF-STEM). The two stacking faults were found to have a stacking sequence of …ABCCABC… and …ABCBCAB…, wh-ich is consistent with a former report. ABF-STEM image simulation was performed using structure models with the { 1 1 ¯00 } stacking faults optimized by first-principles calculations. The overall features of the experimental and the simulated results agree with each other. However, slight differences in contrast were recognized in the vicinity of the stacking faults, suggesting that there are small differences between the observed structures and the theoretical models.

  19. Novel slanted incidence air-coupled ultrasound method for delamination assessment in individual bonding planes of structural multi-layered glued timber laminates.

    PubMed

    Sanabria, Sergio J; Furrer, Roman; Neuenschwander, Jürg; Niemz, Peter; Sennhauser, Urs

    2013-09-01

    Non-destructive assessment of delaminations in glued laminated timber structures is required during their full life cycle. A novel air-coupled ultrasound (ACU) method has been developed, which is able to separately detect delaminations in individual bonding planes of arbitrarily high and long laminated stacks and typically 200 mm wide. The 120 kHz ACU transmitter-receiver pair is positioned at two opposite lateral faces of the sample, with a small inclination with respect to the inspected bonding planes, so that an ultrasound beam is excited at a user-defined refraction angle within the sample, interacting with defects in a limited height portion of the stack. The attenuation of the ultrasound beam transmitted across the defect (negative detection) provided better sensitivity to defects than the scattered fields (positive detection), which are masked by spurious fields. Dedicated finite-difference time-domain (FDTD) simulations provided understanding on the wave propagation and defect detectability limits, with respect to the heterogeneous anisotropic material structure introduced by the curvature of the annual rings in individual timber lamellas. A simplified analytical expression was derived to calculate refraction angles in timber in function of insonification angle and ring angle. Experimental results show that the method is able to detect >20% wide defects in both isotropic material and in glulam with straight year rings, and >50% wide and 100mm long defects in commercial glulam beams. The discrimination of defects from background variability is optimized by normalizing the images with respect to reference defect-free sample sections (normalization) or previous measurements (difference imaging), and by combining readings obtained with distinct ultrasound beam refraction angles (spatial diversity). Future work aims at the development of a tomographic defect inspection by combining the described theoretical and experimental methods. PMID:23664378

  20. Study of defect structures in 6H-SiC a/m-plane pseudofiber crystals grown by hot-wall CVD epitaxy

    SciTech Connect

    Goue, Ouloide Y.; Raghothamachar, Balaji; Yang, Yu; Guo, Jianqiu; Dudley, Michael; Kisslinger, Kim; Trunek, Andrew J.; Neudeck, Philip G.; Spry, David J.; Woodworth, Andrew A.

    2015-11-25

    Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.

  1. Study of Defect Structures in 6H-SiC a/ m-Plane Pseudofiber Crystals Grown by Hot-Wall CVD Epitaxy

    NASA Astrophysics Data System (ADS)

    Goue, Ouloide Y.; Raghothamachar, Balaji; Yang, Yu; Guo, Jianqiu; Dudley, Michael; Kisslinger, Kim; Trunek, Andrew J.; Neudeck, Philip G.; Spry, David J.; Woodworth, Andrew A.

    2016-04-01

    Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/ m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed-epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g· b and g· b× l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed-homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Finally, the implication of these results for improving the LTC growth process is addressed.

  2. Study of defect structures in 6H-SiC a/m-plane pseudofiber crystals grown by hot-wall CVD epitaxy

    DOE PAGESBeta

    Goue, Ouloide Y.; Raghothamachar, Balaji; Yang, Yu; Guo, Jianqiu; Dudley, Michael; Kisslinger, Kim; Trunek, Andrew J.; Neudeck, Philip G.; Spry, David J.; Woodworth, Andrew A.

    2015-11-25

    Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m-plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match themore » polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.« less

  3. Planing of Watercraft

    NASA Technical Reports Server (NTRS)

    Wagner, Herbert

    1948-01-01

    The present report deals with the processes accompanying the planing of a planing boat or a seaplane on water . The study is largely based upon theoretical investigations; mathematical problems and proofs are not discussed. To analyze theoreticaly actual planing processes, giving due consideration to all aspects of the problem, is probably not possible. The theories therefore treat various simple limiting cases, which in their entirety give a picture of the planing processes and enable the interpretation of the experimental results. The discussion is concerned with the stationary planing attitude: the boat planes at a constant speed V on an originally smooth surface.

  4. Variational theory of complex rays applied to shell structures: in-plane inertia, quasi-symmetric ray distribution, and orthotropic materials

    NASA Astrophysics Data System (ADS)

    Cattabiani, Alessandro; Barbarulo, Andrea; Riou, Hervé; Ladevèze, Pierre

    2015-12-01

    Recently, interest of aerospace and automotive industries on medium-frequency vibrational behavior of composite shell structures has grown due to their high specific stiffness and fatigue resistance. Conventional methods such as the finite element method and the statistical energy analysis are not suitable for the medium-frequency bandwidth. Conversely, the variational theory of complex rays (VTCR) is taking place as an ad-hoc technique to tackle such frequency band. It is a Trefftz method based on a weak variational formulation. Equilibrium equations are met using exact solutions as shape functions. The variational problem imposes boundary conditions in weak form. The present paper extends VTCR to orthotropic shell structures. Moreover, several new enhancements are introduced. Now, we use a quasi-symmetric ray distribution which can greatly reduce computational costs, and addresses in-plane inertia which was neglected in previous works. Some relevant numerical examples are presented to show the strategy and results are compared with a FEM reference to study performances.

  5. Cytochrome P450 compound I in the plane wave pseudopotential framework: GGA electronic and geometric structure of thiolate-ligated iron(IV)-oxo porphyrin.

    PubMed

    Elenewski, Justin E; Hackett, John C

    2013-07-15

    The cytochromes P450 constitute a ubiquitous family of metalloenzymes, catalyzing manifold reactions of biological and synthetic importance via a thiolate-ligated iron-oxo (IV) porphyrin radical species denoted compound I (Cpd I). Experimental investigations have implicated this intermediate in a broad spectrum of biophysically interesting phenomena, further augmenting the importance of a Cpd I model system. Ab initio molecular dynamics, including Car-Parrinello and path integral methods, conjoin electronic structure theory with finite temperature simulation, affording tools most valuable to approach such enzymes. These methods are typically driven by density functional theory (DFT) in a plane-wave pseudopotential framework; however, existing studies of Cpd I have been restricted to localized Gaussian basis sets. The appropriate choice of density functional and pseudopotential for such simulations is accordingly not obvious. To remedy this situation, a systematic benchmarking of thiolate-ligated Cpd I is performed using several generalized-gradient approximation (GGA) functionals in the Martins-Troullier and Vanderbilt ultrasoft pseudopotential schemes. The resultant electronic and structural parameters are compared to localized-basis DFT calculations using GGA and hybrid density functionals. The merits and demerits of each scheme are presented in the context of reproducing existing experimental and theoretical results for Cpd I.

  6. Cytochrome P450 compound I in the plane wave pseudopotential framework: GGA electronic and geometric structure of thiolate-ligated iron(IV)-oxo porphyrin.

    PubMed

    Elenewski, Justin E; Hackett, John C

    2013-07-15

    The cytochromes P450 constitute a ubiquitous family of metalloenzymes, catalyzing manifold reactions of biological and synthetic importance via a thiolate-ligated iron-oxo (IV) porphyrin radical species denoted compound I (Cpd I). Experimental investigations have implicated this intermediate in a broad spectrum of biophysically interesting phenomena, further augmenting the importance of a Cpd I model system. Ab initio molecular dynamics, including Car-Parrinello and path integral methods, conjoin electronic structure theory with finite temperature simulation, affording tools most valuable to approach such enzymes. These methods are typically driven by density functional theory (DFT) in a plane-wave pseudopotential framework; however, existing studies of Cpd I have been restricted to localized Gaussian basis sets. The appropriate choice of density functional and pseudopotential for such simulations is accordingly not obvious. To remedy this situation, a systematic benchmarking of thiolate-ligated Cpd I is performed using several generalized-gradient approximation (GGA) functionals in the Martins-Troullier and Vanderbilt ultrasoft pseudopotential schemes. The resultant electronic and structural parameters are compared to localized-basis DFT calculations using GGA and hybrid density functionals. The merits and demerits of each scheme are presented in the context of reproducing existing experimental and theoretical results for Cpd I. PMID:23670855

  7. Optimum design of phononic crystal perforated plate structures for widest bandgap of fundamental guided wave modes and maximized in-plane stiffness

    NASA Astrophysics Data System (ADS)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, Mohammad; Ng, Ching-Tai

    2016-04-01

    This paper presents a topology optimization of single material phononic crystal plate (PhP) to be produced by perforation of a uniform background plate. The primary objective of this optimization study is to explore widest exclusive bandgaps of fundamental (first order) symmetric or asymmetric guided wave modes as well as widest complete bandgap of mixed wave modes (symmetric and asymmetric). However, in the case of single material porous phononic crystals the bandgap width essentially depends on the resultant structural integration introduced by achieved unitcell topology. Thinner connections of scattering segments (i.e. lower effective stiffness) generally lead to (i) wider bandgap due to enhanced interfacial reflections, and (ii) lower bandgap frequency range due to lower wave speed. In other words higher relative bandgap width (RBW) is produced by topology with lower effective stiffness. Hence in order to study the bandgap efficiency of PhP unitcell with respect to its structural worthiness, the in-plane stiffness is incorporated in optimization algorithm as an opposing objective to be maximized. Thick and relatively thin Polysilicon PhP unitcells with square symmetry are studied. Non-dominated sorting genetic algorithm NSGA-II is employed for this multi-objective optimization problem and modal band analysis of individual topologies is performed through finite element method. Specialized topology initiation, evaluation and filtering are applied to achieve refined feasible topologies without penalizing the randomness of genetic algorithm (GA) and diversity of search space. Selected Pareto topologies are presented and gradient of RBW and elastic properties in between the two Pareto front extremes are investigated. Chosen intermediate Pareto topology, even not extreme topology with widest bandgap, show superior bandgap efficiency compared with the results reported in other works on widest bandgap topology of asymmetric guided waves, available in the literature

  8. Rayleigh-wave phase-velocity maps and three-dimensional shear velocity structure of the western US from local non-plane surface wave tomography

    USGS Publications Warehouse

    Pollitz, F.F.; Snoke, J. Arthur

    2010-01-01

    We utilize two-and-three-quarter years of vertical-component recordings made by the Transportable Array (TA) component of Earthscope to constrain three-dimensional (3-D) seismic shear wave velocity structure in the upper 200 km of the western United States. Single-taper spectral estimation is used to compile measurements of complex spectral amplitudes from 44 317 seismograms generated by 123 teleseismic events. In the first step employed to determine the Rayleigh-wave phase-velocity structure, we implement a new tomographic method, which is simpler and more robust than scattering-based methods (e.g. multi-plane surface wave tomography). The TA is effectively implemented as a large number of local arrays by defining a horizontal Gaussian smoothing distance that weights observations near a given target point. The complex spectral-amplitude measurements are interpreted with the spherical Helmholtz equation using local observations about a succession of target points, resulting in Rayleigh-wave phase-velocity maps at periods over the range of 18–125 s. The derived maps depend on the form of local fits to the Helmholtz equation, which generally involve the nonplane-wave solutions of Friederich et al. In a second step, the phase-velocity maps are used to derive 3-D shear velocity structure. The 3-D velocity images confirm details witnessed in prior body-wave and surface-wave studies and reveal new structures, including a deep (>100 km deep) high-velocity lineament, of width ∼200 km, stretching from the southern Great Valley to northern Utah that may be a relic of plate subduction or, alternatively, either a remnant of the Mojave Precambrian Province or a mantle downwelling. Mantle seismic velocity is highly correlated with heat flow, Holocene volcanism, elastic plate thickness and seismicity. This suggests that shallow mantle structure provides the heat source for associated magmatism, as well as thinning of the thermal lithosphere, leading to relatively high

  9. High density load bearing insulation peg

    DOEpatents

    Nowobilski, Jeffert J.; Owens, William J.

    1985-01-01

    A high density peg which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure.

  10. High density load bearing insulation peg

    DOEpatents

    Nowobilski, J.J.; Owens, W.J.

    1985-01-29

    A high density peg is disclosed which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure. 4 figs.

  11. Harmonic plane wave propagation in gyroelectric media

    NASA Astrophysics Data System (ADS)

    Hillion, Pierre

    2006-05-01

    We analyse the behaviour of harmonic plane waves in unbounded gyroelectric media once the refractive index in the direction of propagation is known from the Fresnel equation. We get, for the electric and magnetic fields, analytical expressions simple enough to use in a plane wave spectrum representation of more structured electromagnetic fields in these media. We also discuss the reflection and refraction of harmonic plane waves at the boundary between an isotropic medium and a gyroelectric material.

  12. Electronic structure of the ingredient planes of the cuprate superconductor Bi2Sr2CuO6+δ: A comparison study with Bi2Sr2CaCu2O8+δ

    DOE PAGESBeta

    Yan -Feng Lv; Gu, G. D.; Wang, Wen -Lin; Ding, Hao; Wang, Yang; Ding, Ying; Zhong, Ruidan; Schneeloch, John; Wang, Lili; He, Ke; et al

    2016-04-15

    By means of low-temperature scanning tunneling microscopy, we report on the electronic structures of the BiO and SrO planes of the Bi2Sr2CuO6+δ (Bi-2201) superconductor prepared by argon-ion bombardment and annealing. Depending on post annealing conditions, the BiO planes exhibit either a pseudogap (PG) with sharp coherence peaks and an anomalously large gap magnitude of 49 meV or van Hove singularity (vHS) near the Fermi level, while the SrO is always characteristic of a PG-like feature. This contrasts with the Bi2Sr2CaCu2O8+δ (Bi-2212) superconductor where vHS occurs solely on the SrO plane. We disclose the interstitial oxygen dopants (δ in the formulas)more » as a primary cause for the occurrence of vHS, which are located dominantly around the BiO and SrO planes, respectively, in Bi-2201 and Bi-2212. This is supported by the contrasting structural buckling amplitude of the BiO and SrO planes in the two superconductors. Furthermore, our findings provide solid evidence for the irrelevance of PG to the superconductivity in the two superconductors, as well as insights into why Bi-2212 can achieve a higher superconducting transition temperature than Bi-2201, and by implication, the mechanism of cuprate superconductivity.« less

  13. Load-bearing capacity of indirect inlay-retained fixed dental prostheses made of particulate filler composite alone or reinforced with E-glass fibers impregnated with various monomers.

    PubMed

    Özcan, Mutlu; Koekoek, Winand; Pekkan, Gurel

    2012-08-01

    The load-bearing capacity and failure types of indirect inlay-retained fixed dental prostheses (FDP), made of particulate filler composite (PFC) (Estenia) alone or reinforced with E-glass fibers impregnated with various monomers were evaluated. Indirect inlay-retained FDPs were made between first premolars and first molars (N=30, 10/per group). The inlay parts of the specimens were silica coated and silanized and the specimens were cemented with dual-polymerized resin cement under ultrasonic vibrations. The experimental groups were as follows: Group 1: FRC1 (BR-100, UTMA) + PFC; Group 2: FRC2 (everStick C&B, Bis-GMA/PMMA) + PFC; Group 3: PFC only. The specimens were kept in distilled water at 37 °C for one month and then subjected to fracture strength test. No significant difference was found between the Group 1 and Group 2 FDPs (1357±301 N and 1213±316 N, respectively) (p>0.05) (ANOVA). Group 3 (856±299 N) showed significantly lower results than those of FRC reinforced groups (p<0.05). Failure analyses revealed no debonding of any of the FDPs from the inlay cavities. FDPs made of PFC only showed mainly catastrophic fracture of the pontic. In the FRC reinforced groups, predominantly delamination of the veneering was observed. The use of silica coating and silanization in combination with the dual-polymerized resin cement used; under ultrasonic cementation procedure provided sufficient adhesion to withstand static loading forces at the cementation interface, since the failures were predominantly delamination of the veneering in the FRC reinforced groups.

  14. Mismatch relaxation by stacking fault formation of AlN islands in AlGaN/GaN structures on m-plane GaN substrates

    SciTech Connect

    Smalc-Koziorowska, Julita; Sawicka, Marta; Skierbiszewski, Czeslaw; Grzegory, Izabella

    2011-08-08

    We study the mismatch relaxation of 2-5 nm thin elongated AlN islands formed during growth of AlGaN on bulk m-plane GaN by molecular beam epitaxy. The relaxation of these m-plane AlN layers is anisotropic and occurs through the introduction of stacking faults in [0001] planes during island coalescence, while no relaxation is observed along the perpendicular [1120] direction. This anisotropy in the mismatch relaxation and the formation of stacking faults in the AlN islands are explained by the growth mode of the AlN platelets and their coalescence along the [0001] direction.

  15. Development of material quality and structural design for high performance Type II InAs/GaSb superlattice photodiodes and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Razeghi, Manijeh; Nguyen, Binh-Minh; Hoffman, Darin; Delaunay, Pierre-Yves; Huang, Edward Kwei-wei; Tidrow, Meimei; Nathan, Vaidya

    2008-08-01

    Recent progress made in the structure design, growth and processing of Type-II InAs/GaSb superlattice photo-detectors lifted both the quantum efficiency and the R0A product of the detectors. Type-II superlattice demonstrated its ability to perform imaging in the Mid-Wave Infrared (MWIR) and Long-Wave Infrared (LWIR) ranges, becoming a potential competitor for technologies such as Quantum Well Infrared Photo-detectors (QWIP) and Mercury Cadmium Telluride (MCT). Using an empirical tight-binding model, we developed superlattices designs that were nearly lattice-matched to the GaSb substrates and presented cutoff wavelengths of 5 and 11 μm. We demonstrated high quality material growth with X-ray FWHM below 30 arcsec and an AFM rms roughness of 1.5 Å over an area of 20x20 μm2. The detectors with a 5 μm cutoff, capable of operating at room temperature, showed a R0A of 1.25 106 Ω.cm2 at 77K, and a quantum efficiency of 32%. In the long wavelength infrared, we demonstrated high quantum efficiencies above 50% with high R0A products of 12 Ω.cm2 by increasing the thickness of the active region. Using the novel M-structure superlattice design, more than one order of magnitude improvement has been observed for electrical performance of the devices. Focal plane arrays in the middle and long infrared range, hybridized to an Indigo read out integrated circuit, exhibited high quality imaging.

  16. THE BOLOCAM GALACTIC PLANE SURVEY. XII. DISTANCE CATALOG EXPANSION USING KINEMATIC ISOLATION OF DENSE MOLECULAR CLOUD STRUCTURES WITH {sup 13}CO(1-0)

    SciTech Connect

    Ellsworth-Bowers, Timothy P.; Glenn, Jason; Rosolowsky, Erik; Ginsburg, Adam; Evans II, Neal J.; Battersby, Cara; Shirley, Yancy L.; Svoboda, Brian

    2015-01-20

    We present an expanded distance catalog for 1710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO{sup +}(3-2), NH{sub 3}(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey (GRS) {sup 13}CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region of the GRS {sup 13}CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of {sup 13}CO matched to the BGPS source. For objects with a HCO{sup +}(3-2) velocity, ≈95% of the new {sup 13}CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and H II regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties ≲ 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centaurus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.

  17. Nanostructured carbon films with oriented graphitic planes

    SciTech Connect

    Teo, E. H. T.; Kalish, R.; Kulik, J.; Kauffmann, Y.; Lifshitz, Y.

    2011-03-21

    Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.

  18. Dependence of superconducting transition temperature on doping and structural distortion of the CuO{sub 2} planes in La{sub 2-x}M{sub x}CuO{sub 4} (M=Nd, Ca, Sr).

    SciTech Connect

    Dabrowski, B.; Rogacki, K.; Jorgensen, J. D.; Hinks, D. G.; Materials Science Division; Northern Illinois Univ.

    1996-01-01

    We have separated the structural and doping effects on the superconducting transition temperature in La2-xMxCuO4 (M=Nd, Ca, Sr). At a fixed doping level, the highest Tc is found for flat and square CuO2 planes in the tetragonal structure. Tc is reduced proportionally to the structural distortions of the CuO2 planes in the orthorhombic structure. The local minimum of Tc vs. doping is observed for both orthorhombic Ca- and Sr-substituted materials around x{approx}0.12. This minimum may be related to the intrinsic dependence of the electronic density of states at EF due to a weakly split singularity of DOS.

  19. Experiments with Planing Surfaces

    NASA Technical Reports Server (NTRS)

    Sottorf, W

    1934-01-01

    A previous report discusses the experimental program of a systematic exploration of all questions connected with the planing problem as well as the first fundamental results of the investigation of a flat planing surface. The present report is limited to the conversion of the model test data to full scale.

  20. Effect of out-of-plane directional intra-layer coupling from graphene monolayer on sp3 type defect with gap-plasmonic structures

    NASA Astrophysics Data System (ADS)

    Park, Won-Hwa

    2016-09-01

    The author investigates an intra-layer coupling effect through transverse acoustic (TA) phonon modes along the z-direction at Au nanoparticle (NP)–graphene monolayer (GM)–Au thin film (TF) plasmonic junctions in regard with sp3 type defect effect. The oxidation and resulting disorder of GM with breaking of six-fold symmetry have been explored. Because a Raman-forbidden D peak can be activated due to unwanted single-phonon inter-valley and intra-valley scattering processes, the quantitative estimation of the sp3 type defect is being performed by the intensity ratio between G and D peaks. By exploring the difference of the maximum peak position (TA3-TA1) and the intensity ratio, (TA1/TA3) the author can reveal that a lower z-protruded GM accompanied with weak intra-coupling and a weaker RBLM intensity show relatively high D/G. It means that larger surface area of a GM to be functionalized by oxidization can secure more easily than the higher z-protruded. This investigation presents the importance of controlling the degree of z-protrusion of GM surface in terms of not only the presence of high D/G but also its related and detailed nano-structural surface shape, leading to the enhancement of electrical properties such as a carrier mobility and sheet resistance value. The out-of-plane phonon modes will be considered as a key factor in further exploring nano-physical deformation of 2D materials in sync with its electrical performance.

  1. Effect of out-of-plane directional intra-layer coupling from graphene monolayer on sp3 type defect with gap-plasmonic structures

    NASA Astrophysics Data System (ADS)

    Park, Won-Hwa

    2016-09-01

    The author investigates an intra-layer coupling effect through transverse acoustic (TA) phonon modes along the z-direction at Au nanoparticle (NP)-graphene monolayer (GM)-Au thin film (TF) plasmonic junctions in regard with sp3 type defect effect. The oxidation and resulting disorder of GM with breaking of six-fold symmetry have been explored. Because a Raman-forbidden D peak can be activated due to unwanted single-phonon inter-valley and intra-valley scattering processes, the quantitative estimation of the sp3 type defect is being performed by the intensity ratio between G and D peaks. By exploring the difference of the maximum peak position (TA3-TA1) and the intensity ratio, (TA1/TA3) the author can reveal that a lower z-protruded GM accompanied with weak intra-coupling and a weaker RBLM intensity show relatively high D/G. It means that larger surface area of a GM to be functionalized by oxidization can secure more easily than the higher z-protruded. This investigation presents the importance of controlling the degree of z-protrusion of GM surface in terms of not only the presence of high D/G but also its related and detailed nano-structural surface shape, leading to the enhancement of electrical properties such as a carrier mobility and sheet resistance value. The out-of-plane phonon modes will be considered as a key factor in further exploring nano-physical deformation of 2D materials in sync with its electrical performance.

  2. New plane shear flows

    SciTech Connect

    Conley, A.

    1994-12-31

    A classical problem in fluid dynamics is the study of the stability of plane Couette flow. This flow experimentally sustains turbulence for Reynolds numbers greater than 1440 {+-} 40. (The Reynolds number is based on channel width and wall velocity difference). Since plane Couette flow is linearly stable for all Reynolds numbers, obtaining non-trivial mathematical solutions to the plane Couette flow equations is difficult. However, M. Nagata finds a non-trivial number solution of the plane Couette flow equations at low Reynolds number. We confirm these solutions. We compute the minimum Reynolds number at which they exist. We study their stability. We also study the effect of a Coriolis force on plane Poiseuille flow.

  3. Fourier plane imaging microscopy

    SciTech Connect

    Dominguez, Daniel Peralta, Luis Grave de; Alharbi, Nouf; Alhusain, Mdhaoui; Bernussi, Ayrton A.

    2014-09-14

    We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.

  4. Structure and Function of the Superior Temporal Plane in Adult Males with Cleft Lip and Palate: Pathologic Enlargement with No Relationship to Childhood Hearing Deficits

    ERIC Educational Resources Information Center

    Shriver, A. S.; Canady, J.; Richman, L.; Andreasen, N. C.; Nopoulos, P.

    2006-01-01

    Background: In a previous study from our lab, adult males with non-syndromic cleft lip and/or palate (NSCLP) were shown to have significantly lower temporal lobe gray matter volume than matched controls. The current study was designed to begin a regional analysis of specific subregions of the temporal lobe. The superior temporal plane (STP) is a…

  5. Fixed sagittal plane imbalance.

    PubMed

    Savage, Jason W; Patel, Alpesh A

    2014-12-01

    Study Design Literature review. Objective To discuss the evaluation and management of fixed sagittal plane imbalance. Methods A comprehensive literature review was performed on the preoperative evaluation of patients with sagittal plane malalignment, as well as the surgical strategies to address sagittal plane deformity. Results Sagittal plane imbalance is often caused by de novo scoliosis or iatrogenic flat back deformity. Understanding the etiology and magnitude of sagittal malalignment is crucial in realignment planning. Objective parameters have been developed to guide surgeons in determining how much correction is needed to achieve favorable outcomes. Currently, the goals of surgery are to restore a sagittal vertical axis < 5 cm, pelvic tilt < 20 degrees, and lumbar lordosis equal to pelvic incidence ± 9 degrees. Conclusion Sagittal plane malalignment is an increasingly recognized cause of pain and disability. Treatment of sagittal plane imbalance varies according to the etiology, location, and severity of the deformity. Fixed sagittal malalignment often requires complex reconstructive procedures that include osteotomy correction. Reestablishing harmonious spinopelvic alignment is associated with significant improvement in health-related quality-of-life outcome measures and patient satisfaction.

  6. 2. VIEW SOUTH, INCLINE PLANE CAR, INCLINE PLANE TRACK, UPPER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTH, INCLINE PLANE CAR, INCLINE PLANE TRACK, UPPER STATION. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

  7. Structural polymers in upstream production service

    SciTech Connect

    Dismukes, J.P.; Lustiger, A.; Chang, J.; Abrams, P.I.; Chiu, A.S.

    1993-12-31

    Polymers in the form of coatings, seals and composites for corrosion resistant and secondary load-bearing applications have been used in oilfield production operations for a number of years in specialty applications. The increasing needs of the industry for corrosion resistant piping, and for structural components combining corrosion resistance with high specific strength and weight, have now made the potential for use of polymer composites of increasing interest, for pipe and tubing and for load-bearing structural members. The purpose of this paper is to review the current status of structural polymer usage in the upstream, and to highlight major application areas where there is a strong economic incentive to evaluate the benefits for applying polymer composite. In addition, the underlying science and technology affecting composite properties, application life, environmental resistance and economics are assessed, since these issues need to be addressed in considering the decision to design-in composites, as compared to commonly used metals and alloys.

  8. Structure and Composition of Air-Plane Soots and Surrogates Analyzed by Raman Spectroscopy and Laser/Ions Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ortega, Ismael; Chazallon, Bertrand; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier; Salm, François; Delhaye, David; Gaffié, Daniel; Yon, Jérôme

    2015-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. An aircraft exhaust plume contains species emitted by the engines, species formed in the plume from the emitted species and atmospheric species that become entrained into the plume. The majority of emitted species (gases and soot particles) are produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Emissions of soot particles by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied since many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. Most likely one of the reasons behind these discrepancies resides in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g. with respect to fuel or combustion techniques. In this work, we use Raman microscopy (266, 514 and 785 nm excitation) and ablation techniques (SIMS, Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particles produced from air-plane at different engine regimes simulating a landing and taking-off (LTO) cycle. First, the spectral parameters of the first-order Raman band of various soot samples, collected from three different sources in the frame of the MERMOSE project (http://mermose.onera.fr/): PowerJet SaM-146 turbofan (four engine regimes), CAST generator (propane fuel, four different global equivalence ratios), and Kerosene laboratory flame

  9. Crystal structures of LaO{sub 1−x}F{sub x}BiS{sub 2} (x∼0.23, 0.46): Effect of F doping on distortion of Bi–S plane

    SciTech Connect

    Miura, Akira Nagao, Masanori; Takei, Takahiro; Watauchi, Satoshi; Tanaka, Isao; Kumada, Nobuhiro

    2014-04-01

    The crystal structures of superconducting LaO{sub 1−x}F{sub x}BiS{sub 2} (x∼0.23, 0.46) were determined by single-crystal X-ray diffraction analysis. Their space group was P4/nmm. Distortion of the Bi–S plane changed when the F content was increased from 0.23 to 0.46, and a nearly flat Bi–S plane was formed at x∼0.46. Computational calculations supported this effect of F doping on distortion of Bi–S plane. LaO{sub 1−x}F{sub x}BiS{sub 2} with higher F contents were computationally predicted to be thermodynamically more unstable under ambient pressure. We discussed the bonding, conductivities, and synthetic routes of LaO{sub 1−x}F{sub x}BiS{sub 2}. - Graphical abstract: Distortion of the Bi–S plane in LaO{sub 1−x}F{sub x}BiS{sub 2} changed when the F content was increased from 0.23 to 0.46, and a nearly flat Bi–S plane was formed at x∼0.46 with the appearance of superconductivity. - Highlights: • Crystal structure of LaO{sub 1−x}F{sub x}BiS{sub 2} was determined by single-crystal XRD. • Doping amount of F changes the distortion of the Bi–S plane. • Nearly flat Bi–S planes were found in superconductive LaO{sub 1−x}F{sub x}BiS{sub 2} (x∼0.46). • LaO{sub 1−x}F{sub x}BiS{sub 2} with higher F contents was thermodynamically more unstable. • Bonding, superconductivities, and synthetic routes of LaO{sub 1−x}F{sub x}BiS{sub 2} were discussed.

  10. Enhancement of Optical Polarization Anisotropy of a-Plane InGaN/GaN Multiple Quantum Well Structure from Violet to Blue-Green Light

    NASA Astrophysics Data System (ADS)

    Su, Sheng-Han; Huang, Shyh-Jer; Su, Yan-Kuin; Hsu, Hsiao-Chiu

    2013-01-01

    A nonpolar a-plane (1120) InGaN/GaN epitaxial layer was grown on r-plane (1012) sapphire substrates by metal-organic chemical vapor deposition (MOCVD). In this work, a set of step-stage multiple quantum wells (MQWs) is inserted between underlying GaN and overlying high indium-content MQWs to investigate its influence on the optical properties of the active region. The step-stage MQWs were deposited by varying growth temperature at fixed precursor flow rate. Optical properties were investigated by the measurement of temperature-dependent photoluminescence (TD-PL). The optical polarization ratio, activation energy, and the smile-like curve in full width at half maximum (FWHM) of PL were analyzed in detail.

  11. SNAP focal plane

    SciTech Connect

    Lampton, Michael L.; Kim, A.; Akerlof, C.W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E.; Bebek, C.; Bergstrom, L.; Berkovitz, J.; Bernstein, G.; Bester, M.; Bonissent, A.; Bower, C.; Carithers Jr., W.C.; Commins, E.D.; Day, C.; Deustua, S.E.; DiGennaro,R.; Ealet, A.; Ellis, R.S.; Eriksson, M.; Fruchter, A.; Genat, J.-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Harris, S.E.; Harvey, P.R.; Heetderks, H.D.; Holland, S.E.; Huterer, D.; Karcher, A.; Kolbe, W.; Krieger, B.; Lafever, R.; Lamoureux, J.; Levi, M.E.; Levin, D.S.; Linder,E.V.; Loken, S.C.; Malina, R.; Massey, R.; McKay, T.; McKee, S.P.; Miquel, R.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Pratt, R.; Prieto, E.; Refregier, A.; Rhodes, J.; Robinson, K.; Roe, N.; Sholl, M.; Schubnell, M.; Smadja, G.; Smoot, G.; Spadafora, A.; Tarle, G.; Tomasch,A.; von der Lippe, H.; Vincent, R.; Walder, J.-P.; Wang, G.

    2002-07-29

    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation--visible and near-infrared imagers, spectrograph, and star guiders--share one common focal plane.

  12. Three-dimensional Allan fault plane analysis

    SciTech Connect

    Hoffman, K.S.; Taylor, D.R.; Schnell, R.T.

    1994-12-31

    Allan fault-plane analysis is a useful tool for determining hydrocarbon migration paths and the location of possible traps. While initially developed for Gulf coast deltaic and interdeltaic environments, fault-plane analysis has been successfully applied in many other geologic settings. Where the geology involves several intersecting faults and greater complexity, many two-dimensional displays are required in the investigation and it becomes increasingly difficult to accurately visualize both fault relationships and migration routes. Three-dimensional geospatial fault and structure modeling using computer techniques, however, facilitates both visualization and understanding and extends fault-plane analysis into much more complex situations. When a model is viewed in three dimensions, the strata on both sides of a fault can be seen simultaneously while the true structural character of one or more fault surfaces is preserved. Three-dimensional analysis improves the speed and accuracy of the fault plane methodology.

  13. Effect of CuO2 planes on the structural and superconducting transport properties of [CuTl - 12(n - 1)n;n = 2,3,4] superconductor family

    NASA Astrophysics Data System (ADS)

    Muzaffar, M. Usman; Khan, Nawazish A.

    2016-06-01

    Cu0.5Tl0.5Ba2Can-1CunO2n+4-δ (n = 2, 3, 4) superconducting bulk samples have been synthesized by using two-step solid state reaction method. We investigated the effects of CuO2 planes on the structural and superconducting transport properties of [CuTl - 12(n - 1)n; n = 2, 3, 4] superconducting family. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) absorption spectroscopy and DC-resistivity (ρ) measurements. These samples are c-axis length oriented and have shown orthorhombic crystal structure. All the samples have shown metallic variations of resistivity from room temperature down to onset of superconductivity. The zero resistivity critical temperature Tc(R = 0) increases with the increase in superconducting planes and normal state resistivity systematically decreases, which show the density of inadvertent defects decreases in the final compound. The apical oxygen phonon modes are hardened as observed in the FTIR absorption measurements. The intrinsic microscopic superconducting parameters, such as the cross-over temperatures, coherence length along c-axis (ξc(0)) at 0 K, inter-layer coupling (J), inter-grain coupling (α) and fermi velocity (VF), were extracted from the fluctuation-induced conductivity (FIC) analysis. FIC analysis also showed the improvement in superconductivity with the increase in CuO2 planes.

  14. Effect of CuO2 planes on the structural and superconducting transport properties of [CuTl ‑ 12(n ‑ 1)n;n = 2,3,4] superconductor family

    NASA Astrophysics Data System (ADS)

    Muzaffar, M. Usman; Khan, Nawazish A.

    2016-06-01

    Cu0.5Tl0.5Ba2Can‑1CunO2n+4‑δ (n = 2, 3, 4) superconducting bulk samples have been synthesized by using two-step solid state reaction method. We investigated the effects of CuO2 planes on the structural and superconducting transport properties of [CuTl ‑ 12(n ‑ 1)n; n = 2, 3, 4] superconducting family. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) absorption spectroscopy and DC-resistivity (ρ) measurements. These samples are c-axis length oriented and have shown orthorhombic crystal structure. All the samples have shown metallic variations of resistivity from room temperature down to onset of superconductivity. The zero resistivity critical temperature Tc(R = 0) increases with the increase in superconducting planes and normal state resistivity systematically decreases, which show the density of inadvertent defects decreases in the final compound. The apical oxygen phonon modes are hardened as observed in the FTIR absorption measurements. The intrinsic microscopic superconducting parameters, such as the cross-over temperatures, coherence length along c-axis (ξc(0)) at 0 K, inter-layer coupling (J), inter-grain coupling (α) and fermi velocity (VF), were extracted from the fluctuation-induced conductivity (FIC) analysis. FIC analysis also showed the improvement in superconductivity with the increase in CuO2 planes.

  15. Foam rigidized inflatable structural assemblies

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L. (Inventor); Schnell, Andrew R. (Inventor)

    2010-01-01

    An inflatable and rigidizable structure for use as a habitat or a load bearing structure is disclosed. The structure consists of an outer wall and an inner wall defining a containment member and a bladder. The bladder is pressurized to erect the structure from an initially collapsed state. The containment member is subsequently injected with rigidizable fluid through an arrangement of injection ports. Exhaust gases from the curing rigidizable fluid are vented through an arrangement of exhaust ports. The rate of erection can be controlled by frictional engagement with a container or by using a tether. A method for fabricating a tubular structure is disclosed.

  16. Self-accommodation of B19' martensite in Ti-Ni shape memory alloys - Part II. Characteristic interface structures between habit plane variants

    NASA Astrophysics Data System (ADS)

    Nishida, M.; Okunishi, E.; Nishiura, T.; Kawano, H.; Inamura, T.; S., Ii; Hara, T.

    2012-06-01

    Four characteristic interface microstructures between habit plane variants (HPVs) in the self-accommodation morphologies of B19‧ martensite in Ti-Ni alloys have been investigated by scanning transmission electron microscopy (STEM). The straight interface of a ? B19‧ type I twin is present at interface I. The relaxation of the transformation strain at interface II is achieved by a volume reduction of the minor correspondence variants (CVs) in the relevant habit plane variants (HPVs). The relaxation of the transformation strain at interface III is mainly due to the formation of a ? B19‧ type I twin between the two major CVs. Subsequently, local strain around the tips of the minor CVs perpendicular to the interface is released by the formation of micro-twins with the ⟨011⟩B19‧ type II and/or ? B19‧ type I relation. The major and minor CVs in each HPV are alternately connected through fine variants with the ? B19‧ type I twin relation parallel to interface IV. The results are compared with macroscopic observations and the predictions of PTMC analysis.

  17. Double plane wave reverse time migration with plane wave Green's function

    NASA Astrophysics Data System (ADS)

    Zhao, Z.; Sen, M. K.; Stoffa, P. L.

    2015-12-01

    Reverse time migration (RTM) is effective in obtaining complex subsurface structures from seismic data. By solving the two-way wave equation, RTM can use entire wavefield for imaging. Although powerful computer are becoming available, the conventional pre-stack shot gather RTM is still computationally expensive. Solving forward and backward wavefield propagation for each source location and shot gather is extremely time consuming, especially for large seismic datasets. We present an efficient, accurate and flexible plane wave RTM in the frequency domain where we utilize a compressed plane wave dataset, known as the double plane wave (DPW) dataset. Provided with densely sampled seismic dataset, shot gathers can be decomposed into source and receiver plane wave components with minimal artifacts. The DPW RTM is derived under the Born approximation and utilizes frequency domain plane wave Green's function for imaging. Time dips in the shot profiles can help to estimate the range of plane wave components present in shot gathers. Therefore, a limited number of plane wave Green's functions are needed for imaging. Plane wave Green's functions can be used for imaging both source and receiver plane waves. Source and receiver reciprocity can be used for imaging plane wave components at no cost and save half of the computation time. As a result, the computational burden for migration is substantially reduced. Plane wave components can be migrated independently to recover specific targets with given dips, and ray parameter common image gathers (CIGs) can be generated after migration directly. The ray parameter CIGs can be used to justify the correctness of velocity models. Subsurface anisotropy effects can also be included in our imaging condition, provided with plane wave Green's functions in the anisotropic media.

  18. Deep plane facelifting for facial rejuvenation.

    PubMed

    Gordon, Neil; Adam, Stewart

    2014-08-01

    The purpose of this article is to provide the facial plastic surgeon with anatomical and embryologic evidence to support the use of the deep plane technique for optimal treatment of facial aging. A detailed description of the procedure is provided to allow safe and consistent performance. Insights into anatomical landmarks, technical nuances, and alternative approaches for facial variations are presented. The following points will be further elucidated in the article. The platysma muscle/submuscular aponeurotic system/galea are the continuous superficial cervical fascia encompassing the majority of facial fat, and this superficial soft tissue envelope is poorly anchored to the face. The deep cervical fascia binds the structural aspects of the face and covers the facial nerve and buccal fat pad. Facial aging is mainly due to gravity's long-term effects on the superficial soft tissue envelope, with more subtle effects on the deeper structural compartments. The deep plane is the embryologic cleavage plane between these fascial layers, and is the logical place for facial dissection. The deep plane allows access to the buccal fat pad for treatment of jowling. Soft tissue mobilization is maximized in deep plane dissections and requires careful hairline planning. Flap advancement creates tension only at the fascia level allowing natural, tension-free skin closure, and long-lasting outcomes. The deep plane advancement flap is well vascularized and resistant to complications.

  19. Structural Characterization of Lateral-grown 6H-SiC am-plane Seed Crystals by Hot Wall CVD Epitaxy

    NASA Technical Reports Server (NTRS)

    Goue, Ouloide Yannick; Raghothamachar, Balaji; Dudley, Michael; Trunek, Andrew J.; Neudeck, Philip G.; Woodworth, Andrew A.; Spry, David J.

    2014-01-01

    The performance of commercially available silicon carbide (SiC) power devices is limited due to inherently high density of screw dislocations (SD), which are necessary for maintaining polytype during boule growth and commercially viable growth rates. The NASA Glenn Research Center (GRC) has recently proposed a new bulk growth process based on axial fiber growth (parallel to the c-axis) followed by lateral expansion (perpendicular to the c-axis) for producing multi-faceted m-plane SiC boules that can potentially produce wafers with as few as one SD per wafer. In order to implement this novel growth technique, the lateral homoepitaxial growth expansion of a SiC fiber without introducing a significant number of additional defects is critical. Lateral expansion is being investigated by hot wall chemical vapor deposition (HWCVD) growth of 6H-SiC am-plane seed crystals (0.8mm x 0.5mm x 15mm) designed to replicate axially grown SiC single crystal fibers. The post-growth crystals exhibit hexagonal morphology with approximately 1500 m (1.5 mm) of total lateral expansion. Preliminary analysis by synchrotron white beam x-ray topography (SWBXT) confirms that the growth was homoepitaxial, matching the polytype of the respective underlying region of the seed crystal. Axial and transverse sections from the as grown crystal samples were characterized in detail by a combination of SWBXT, transmission electron microscopy (TEM) and Raman spectroscopy to map defect types and distribution. X-ray diffraction analysis indicates the seed crystal contained stacking disorders and this appears to have been reproduced in the lateral growth sections. Analysis of the relative intensity for folded transverse acoustic (FTA) and optical (FTO) modes on the Raman spectra indicate the existence of stacking faults. Further, the density of stacking faults is higher in the seed than in the grown crystal. Bundles of dislocations are observed propagating from the seed in m-axis lateral directions

  20. Carbon nanotube plane fastener

    NASA Astrophysics Data System (ADS)

    Hirahara, Kaori; Ajioka, Shoichi; Nakayama, Yoshikazu

    2011-12-01

    We report a feature of carbon nanotubes (CNTs) that arises when the surfaces of two vertically-aligned CNT brushes are pressed together. Adhesion between the CNTs creates a plane fastener-like device. Observations from scanning electron microscopy and measurements of adhesion properties indicate a device-dependence on CNT density and shape near the tip region. Among other applications, such fasteners have the potential to attach small components onto micron-sized electronic devices.

  1. Full-scale testing and numerical modeling of a multistory masonry structure subjected to internal blast loading

    NASA Astrophysics Data System (ADS)

    Zapata, Brian Jarvis

    As military and diplomatic representatives of the United States are deployed throughout the world, they must frequently make use of local, existing facilities; it is inevitable that some of these will be load bearing unreinforced masonry (URM) structures. Although generally suitable for conventional design loads, load bearing URM presents a unique hazard, with respect to collapse, when exposed to blast loading. There is therefore a need to study the blast resistance of load bearing URM construction in order to better protect US citizens assigned to dangerous locales. To address this, the Department of Civil and Environmental Engineering at the University of North Carolina at Charlotte conducted three blast tests inside a decommissioned, coal-fired, power plant prior to its scheduled demolition. The power plant's walls were constructed of URM and provided an excellent opportunity to study the response of URM walls in-situ. Post-test analytical studies investigated the ability of existing blast load prediction methodologies to model the case of a cylindrical charge with a low height of burst. It was found that even for the relatively simple blast chamber geometries of these tests, simplified analysis methods predicted blast impulses with an average net error of 22%. The study suggested that existing simplified analysis methods would benefit from additional development to better predict blast loads from cylinders detonated near the ground's surface. A hydrocode, CTH, was also used to perform two and three-dimensional simulations of the blast events. In order to use the hydrocode, Jones Wilkins Lee (JWL) equation of state (EOS) coefficients were developed for the experiment's Unimax dynamite charges; a novel energy-scaling technique was developed which permits the derivation of new JWL coefficients from an existing coefficient set. The hydrocode simulations were able to simulate blast impulses with an average absolute error of 34.5%. Moreover, the hydrocode simulations

  2. Resonance reflection of elastic waves at the interface between two crystals with sliding contact: II. Plane waves and acoustic beams in structures with hexagonal symmetry

    SciTech Connect

    Alshits, V.I.; Darinskii, A.N.; Radovich, A.

    1995-05-01

    The specific features of acoustic wave reflection are analyzed at the interface between two hexagonal crystals with a sliding contact between them. Attention is focused on the angles of incidence corresponding to excitation of the leaky wave. The conditions supporting the existence of leaky waves are found. The expressions illustrating the behavior of plane wave transformation coefficients for reflection, refraction, and excitation of interfacial oscillations are found in analytic form. In addition, the features of nonmirror reflection are studied for a slightly diverging acoustic beam having initially a rectangular profile. The study deals with the case when the tangential projection of the {open_quotes}mean{close_quotes} wavevector for the beam is close to or coincides with the real part of the wavevector of the leaky wave. 9 refs., 10 figs.

  3. Chlamydia trachomatis protein CT009 is a structural and functional homolog to the key morphogenesis component RodZ and interacts with division septal plane localized MreB

    PubMed Central

    Kemege, Kyle E.; Hickey, John M.; Barta, Michael L.; Wickstrum, Jason; Balwalli, Namita; Lovell, Scott; Battaile, Kevin P.; Hefty, P. Scott

    2015-01-01

    Summary Cell division in Chlamydiae is poorly understood as apparent homologs to most conserved bacterial cell division proteins are lacking and presence of elongation (rod shape) associated proteins indicate non-canonical mechanisms may be employed. The rod-shape determining protein MreB has been proposed as playing a unique role in chlamydial cell division. In other organisms, MreB is part of an elongation complex that requires RodZ for proper function. A recent study reported that the protein encoded by ORF CT009 interacts with MreB despite low sequence similarity to RodZ. The studies herein expand on those observations through protein structure, mutagenesis, and cellular localization analyses. Structural analysis indicated that CT009 shares high level of structural similarity to RodZ, revealing the conserved orientation of two residues critical for MreB interaction. Substitutions eliminated MreB protein interaction and partial complementation provided by CT009 in RodZ deficient E. coli. Cellular localization analysis of CT009 showed uniform membrane staining in Chlamydia. This was in contrast to the localization of MreB, which was restricted to predicted septal planes. MreB localization to septal planes provides direct experimental observation for the role of MreB in cell division and supports the hypothesis that it serves as a functional replacement for FtsZ in Chlamydia. PMID:25382739

  4. The combined effect of frontal plane tibiofemoral knee angle and meniscectomy on the cartilage contact stresses and strains.

    PubMed

    Yang, Nicholas; Nayeb-Hashemi, Hamid; Canavan, Paul K

    2009-11-01

    Abnormal tibiofemoral alignment can create loading conditions at the knee that may lead to the initiation and progression of knee osteoarthritis (OA). The degenerative changes of the articular cartilage may occur earlier and with greater severity in individuals with abnormal frontal plane tibiofemoral alignment who undergo a partial or total meniscectomy. In this investigation, subject specific 3D finite element knee models were created from magnetic resonance images of two female subjects to study the combined effect of frontal plane tibiofemoral alignment and total and partial meniscectomy on the stress and strain at the knee cartilage. Different amounts of medial and lateral meniscectomies were modeled and subject specific loading conditions were determined from motion analysis and force platform data during single-leg support. The results showed that the maximum stresses and strains occurred on the medial tibial cartilage after medial meniscectomy but a greater percentage change in the contact stresses and strains occurred in the lateral cartilage after lateral meniscectomy for both subjects due to the resultant greater load bearing role of the lateral meniscus. The results indicate that individual's frontal plane knee alignment and their unique local force distribution between the cartilage and meniscus play an important role in the biomechanical effects of total and partial meniscectomy.

  5. Focal Plane Instrumentation of VERITAS

    NASA Astrophysics Data System (ADS)

    Nagai, T.; McKay, R.; Sleege, G.; Petry, D.

    VERITAS is a new atmospheric Cherenkov imaging telescope array to detect very high energy gamma rays above 100 GeV. The array is located in southern Arizona, USA, at an altitude of 1270m above see level. The array currently consists of four 12 m telescopes, structurally resembling the Davis-Cotton design of the Whipple 10 m telescope. The VERITAS focal plane instruments are equipped with high-resolution (499 pixels) fast photo-multiplier-tube (PMT) cameras covering a 3.5 degree field of view with 0.148 degree pixel separation. Light concentrators reduce the dead-space between PMTs to 25% and shield the PMTs from ambient light. The PMTs are connected to high-speed pre-amplifiers improving the signal to noise ratio and allow single photoelectron measurements in situ at operating voltage. Current monitor circuits in the focus box provide real-time monitoring of the anode currents for each pixel and ambient conditions of the focus box. A charge injection system installed in the focus box allows daytime testing of the trigger and data acquisition system by injecting pulses of variable amplitude and length into pre-amplifier stage. A detailed description of the VERITAS focal plane instruments will be given in this presentation.

  6. Interfacial structure and defect analysis of nonpolar ZnO films grown on R-plane sapphire by molecular beam epitaxy

    SciTech Connect

    Vennegues, P.; Korytov, M.; Deparis, C.; Zuniga-Perez, J.; Morhain, C.; Chauveau, J. M.

    2008-04-15

    The interfacial relationship and the microstructure of nonpolar (11-20) ZnO films epitaxially grown on (1-102) R-plane sapphire by molecular beam epitaxy are investigated by transmission electron microscopy. The already-reported epitaxial relationships [1-100]{sub ZnO} parallel [11-20]{sub sapphire} and <0001>{sub ZnO} parallel [-1101]{sub sapphire} are confirmed, and we have determined the orientation of the Zn-O (cation-anion) bond along [0001]{sub ZnO} in the films as being uniquely defined with respect to a reference surface Al-O bond on the sapphire substrate. The microstructure of the films is dominated by the presence of I{sub 1} basal stacking faults [density=(1-2)x10{sup 5} cm{sup -1}] and related partial dislocations [density=(4-7)x10{sup 10} cm{sup -2}]. It is shown that I{sub 1} basal stacking faults correspond to dissociated perfect dislocations, either c or a+c type.

  7. Structural TEM study of nonpolar a-plane gallium nitride grown on(112_0) 4H-SiC by organometallic vapor phase epitaxy

    SciTech Connect

    Zakharov, Dmitri N.; Liliental-Weber, Zuzanna; Wagner, Brian; Reitmeier,Zachary J.; Preble, Edward A.; Davis, Robert F.

    2005-04-05

    Conventional and high resolution electron microscopy havebeen applied for studying lattice defects in nonpolar a-plane GaN grownon a 4H-SiC substrate with an AlN buffer layer. Samples in plan-view andcross-section configurations have been investigated. Basal and prismaticstacking faults together with Frank and Shockley partial dislocationswere found to be the main defects in the GaN layers. High resolutionelectron microscopy in combination with image simulation supported Drum smodel for the prismatic stacking faults. The density of basal stackingfaults was measured to be ~;1.6_106cm-1. The densities of partialdislocations terminating I1 and I2 types of intrinsic basal stackingfaults were ~;4.0_1010cm-2 and ~;0.4_1010cm-2, respectively. The energyof the I2 stacking fault in GaN was estimated to be (40+-4) erg/cm2 basedon the separation of Shockley partial dislocations. To the best of ourknowledge, the theoretically predicted I3 basal stacking fault in GaN wasobserved experimentally for the first time.

  8. Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates Pr x Y1-x Fe3(BO3)4: magnetic properties and crystal field calculations

    NASA Astrophysics Data System (ADS)

    Pankrats, A. I.; Demidov, A. A.; Ritter, C.; Velikanov, D. A.; Semenov, S. V.; Tugarinov, V. I.; Temerov, V. L.; Gudim, I. A.

    2016-10-01

    The magnetic structure of the mixed rare-earth system Pr x Y1-x Fe3(BO3)4 (x  =  0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x  =  0.67 ÷ 0.45. In the compounds with x  =  0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field. An approach based on a crystal field model for the Pr3+ ion and the molecular-field approximation is used to describe the magnetic characteristics of the system Pr x Y1-x Fe3(BO3)4. With the parameters of the d-d and f-d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2-300 K).

  9. Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates Pr x Y1-x Fe3(BO3)4: magnetic properties and crystal field calculations.

    PubMed

    Pankrats, A I; Demidov, A A; Ritter, C; Velikanov, D A; Semenov, S V; Tugarinov, V I; Temerov, V L; Gudim, I A

    2016-10-01

    The magnetic structure of the mixed rare-earth system Pr x Y1-x Fe3(BO3)4 (x  =  0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x  =  0.67 ÷ 0.45. In the compounds with x  =  0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field. An approach based on a crystal field model for the Pr(3+) ion and the molecular-field approximation is used to describe the magnetic characteristics of the system Pr x Y1-x Fe3(BO3)4. With the parameters of the d-d and f-d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2-300 K).

  10. The Three Planes of Language.

    ERIC Educational Resources Information Center

    Sampson, Gloria

    1999-01-01

    Currently, the language sciences place together four different forms of mental activity on one plane of language, which results in confusion. This paper presents arguments from metaphysics, hermeneutics, and semiotics to demonstrate that there are actually three planes of language (a biologically-based information processing plane, a literal…

  11. The Aerodynamic Plane Table

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1924-01-01

    This report gives the description and the use of a specially designed aerodynamic plane table. For the accurate and expeditious geometrical measurement of models in an aerodynamic laboratory, and for miscellaneous truing operations, there is frequent need for a specially equipped plan table. For example, one may have to measure truly to 0.001 inch the offsets of an airfoil at many parts of its surface. Or the offsets of a strut, airship hull, or other carefully formed figure may require exact calipering. Again, a complete airplane model may have to be adjusted for correct incidence at all parts of its surfaces or verified in those parts for conformance to specifications. Such work, if but occasional, may be done on a planing or milling machine; but if frequent, justifies the provision of a special table. For this reason it was found desirable in 1918 to make the table described in this report and to equip it with such gauges and measures as the work should require.

  12. Fourier plane image amplifier

    DOEpatents

    Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.

    1995-12-12

    A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.

  13. Fourier plane image amplifier

    DOEpatents

    Hackel, Lloyd A.; Hermann, Mark R.; Dane, C. Brent; Tiszauer, Detlev H.

    1995-01-01

    A solid state laser is frequency tripled to 0.3 .mu.m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only .about.1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power.

  14. The effect of prior out-of-plane damage on the in-plane behavior of unreinforced masonry infilled frames

    SciTech Connect

    Henderson, R.C.; Jones, W.D.; Burdette, E.G.; Porter, M.L.

    1993-08-25

    In order to address the effect of prior out-of-plane damage on the in-plane behavior of unreinforced masonry infills, two full-scale (24 feet tall by 28 feet long) structural clay tile infills and one frame-only (no infilling) were constructed and tested. The infilled frame, consisting of two wide flange columns surrounded by masonry plasters and an eccentric wide flange purlin, was identical to many of the infills located at the Oak Ridge Y-12 Plant. The masonry infill was approximately 12.5 inches thick and was composed of individual four- and eight-inch hollow clay tile (HCT) units. One of the infill panels was tested out-of-plane by four quasi-static actuators -- two on each column. The test structure was deflected out-of-plane equally at all four actuator locations in order to simulate the computed deflection path of the top and bottom chords of a roof truss framing into the columns at these locations. Prior to the infill testing, a bare frame was loaded similarly in order to determine the behavior and stiffness contribution of the frame only. Following the out-of-plane test of the infilled panel, the structure was loaded in-plane to failure in order to ascertain residual strength. A second, identical infilled frame was then constructed and tested in-plane to failure. In this way, in-plane behavior with and without prior out-of-plane damage could be established and compared. For both out-of-plane and in-plane testing, reversed-cyclic quasi-static loading was used in order to obtain full tension/compression hystereses. Also, natural frequencies of the first infilled panel were determined before and after the out-of-plane testing. This paper describes the test series and discusses the conclusions pertinent to the effect of out-of-plane cracking on in-plane stiffness and behavior.

  15. The primal sagittal plane of the head: a new concept.

    PubMed

    Gateno, J; Jajoo, A; Nicol, M; Xia, J J

    2016-03-01

    To assess facial form, one has to determine the size, position, orientation, shape, and symmetry of the different facial units. Many of these assessments require a frame of reference. The customary coordinate system used for these assessments is the 'standard anatomical frame of reference', a three-dimensional Cartesian system made by three planes: the sagittal, the axial, and the coronal. Constructing the sagittal plane seems simple, but because of universal facial asymmetry, it is complicated. Depending on the method one selects, one can build hundreds of different planes, never knowing which one is correct. This conundrum can be solved by estimating the sagittal plane a patient would have had if his or her face had developed symmetrically. We call this the 'primal sagittal plane'. To estimate this plane we have developed a mathematical algorithm called LAGER (Landmark Geometric Routine). In this paper, we explain the concept of the primal sagittal plane and present the structure of the LAGER algorithm.

  16. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains how our weather occurs, and why Solar radiation is responsible. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  17. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how they form. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  18. NASA Connect: 'Plane Weather'

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Excerpt from the NASA Connect show 'Plane Weather' This clip explains what high and low pressure weather systems are, and how these affect weather patterns. Weather affects our daily lives. The elements of weather: rain, wind, fog, ice and snow affect the operation and flight of an airplane. In this program, NASA and FAA researchers will introduce students to math, science, and weather; demonstrate how these elements influence flight; and show how NASA and FAA research is used to limit the effects of these elements on flight. Students will examine: the tools, techniques, and technologies used by engineers and scientists to detect these and other climatological factors affecting aircraft in flight. The lesson and classroom experiment will involve students in the scientific process and emphasizing problem solving, measurement, and reasoning skills.

  19. Finite difference time domain modeling of finite-sized electromagnetic source over periodic structure via a plane wave spectral expansion approach

    NASA Astrophysics Data System (ADS)

    Qiang, Rui; Chen, Ji; Yang, Fan

    2010-10-01

    A novel three-dimensional time domain method is developed to study interactions between finite-sized electromagnetic sources and infinite periodic structures. The method is based on a periodic finite difference time domain method combined with the spectral expansion of electromagnetic sources. Using this method, only a single periodic cell needs to be modeled in finite difference time domain simulations. The convergence, guidelines on using the algorithm, and the acceleration scheme for the algorithm are discussed. Several periodic structures are simulated by this proposed method. It is shown that this method can significantly reduce the required computer memory and computational time.

  20. Mn concentration dependent structural and optical properties of a-plane Zn{sub 0.99-x}Mn{sub x}Na{sub 0.01}O

    SciTech Connect

    Lu, B. Zhou, T. T.; Ma, M. J.; Ye, Y. H.; Ye, Z. Z.; Lu, J. G.; Pan, X. H.

    2013-12-14

    Non-polar a-plane (112{sup ¯}0) Zn{sub 0.99−x}Mn{sub x}Na{sub 0.01}O (x = 0, 0.02, 0.03, 0.04, and 0.05) thin films have been prepared on r-plane (112{sup ¯}0) sapphire substrates by pulsed laser deposition (PLD). The influences of Mn content on the structural and optical properties of the films have been studied. It is indicated that moderate Mn doping facilitates the non-polar growth of ZnO, and all the doped films are single phase with a hexagonal wurtzite structure. The transmittance spectra suggested that all films are transparent in the visible region exhibiting a transmittance above 80%. Mn{sup 2+} doped Zn{sub 0.99}Na{sub 0.01}O shows an initial decrease of optical band gap (OBG) for small concentration of Mn, followed by a monotonic increase. The anomalous decrease in OBG for low concentrations of Mn is attributed to the strong exchange interaction present between the sp electrons of the host matrix and d electrons of Mn. Emission studies were also performed showing suppressed blue-shifted ultraviolet band and dominant violet-blue bands, which might originate from the zinc vacancy (V{sub Zn}) and zinc interstitial (Zn{sub i}) defects. The intensity of defect-related emission peaks is Mn doping-level-dependent as well and the results coincide well with that from the structural analyses.

  1. Stabilization of endangered part of structures by building dry brunt brick buttressing, critical case study of plane wall in DKG-North Area, Mohenjo daro

    NASA Astrophysics Data System (ADS)

    Shaikh, J. M.; Park, J.

    2013-07-01

    'World Heritage Sites' are places or buildings of outstanding universal value recognized as constituting a world heritage 'for whose protection it is the duty of the international community as a whole to co-operate'. The concept of World Heritage is at the core of the World Heritage Convention, adopted by Heritage List as a means of identifying, protecting, conserving and presenting those parts of the world's natural and cultural heritage that are of sufficient 'outstanding universal value' to be the responsibility of the international community as a whole. By joining the Convention, nation states are pledged to safeguard the WH S by protecting their national heritage. UNESCO in 1972, to which 160 nations have now been adhered. The Convention came into force in 1975 and established a Site in their territory as part of a universally agreed policy for World. Moenjodaro site covering an area of 555 Acres out of which only 10 % of it has been excavated by exposing 50 Kilometer standing walls. The wall of the main street of DK G Area, Mohen jo Daro partially deformed, due to the torque effects this is studied here on a lateral cross wall in the chief house. Furthermore, the resulting behaviour of the bucking wall demonstrates the significant loadbearing capacity of the structure under service conditions and its high sensitivity to imposed changes of the geometry. Although the tensile stresses exceeded the flexural strength at the vertices and the length of the wall, hence both the geometry and condition of this area are critical for the safety of the wall. The results of this study can improve the assessment and thus help in the preservation of many important structures of the metropolitan city. Here the hydrous characteristic of the brick is studied as a general phenomenon, it is observed that the remains of the sites located in Sindh suffered a lot mostly due to age, human neglect variations of atmospheric condition, severe temperature and natural disasters. The main

  2. Combinatorial Intricacies of Labeled Fano Planes

    NASA Astrophysics Data System (ADS)

    Saniga, Metod

    2016-08-01

    Given a seven-element set $X = \\{1,2,3,4,5,6,7\\}$, there are 30 ways to define a Fano plane on it. Let us call a line of such Fano plane, that is to say an unordered triple from $X$, ordinary or defective according as the sum of two smaller integers from the triple is or is not equal to the remaining one, respectively. A point of the labeled Fano plane is said to be of order $s$, $0 \\leq s \\leq 3$, if there are $s$ {\\it defective} lines passing through it. With such structural refinement in mind, the 30 Fano planes are shown to fall into eight distinct types. Out of the total of 35 lines, nine ordinary lines are of five different kinds, whereas the remaining 26 defective lines yield as many as ten distinct types. It is shown, in particular, that no labeled Fano plane can have all points of zeroth order, or feature just one point of order two. A connection with prominent configurations in Steiner triple systems is also pointed out.

  3. Ultrawide phononic band gap for combined in-plane and out-of-plane waves.

    PubMed

    Bilal, Osama R; Hussein, Mahmoud I

    2011-12-01

    We consider two-dimensional phononic crystals formed from silicon and voids, and present optimized unit-cell designs for (1) out-of-plane, (2) in-plane, and (3) combined out-of-plane and in-plane elastic wave propagation. To feasibly search through an excessively large design space (~10(40) possible realizations) we develop a specialized genetic algorithm and utilize it in conjunction with the reduced Bloch mode expansion method for fast band-structure calculations. Focusing on high-symmetry plain-strain square lattices, we report unit-cell designs exhibiting record values of normalized band-gap size for all three categories. For the case of combined polarizations, we reveal a design with a normalized band-gap size exceeding 60%.

  4. Visualization of microvascular proliferation as a tumor infiltration structure in rat glioma specimens using the diffraction-enhanced imaging in-plane CT technique

    NASA Astrophysics Data System (ADS)

    Seo, Seung-Jun; Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ando, Masami; Choi, Gi-Hwan; Kim, Hong-Tae; Kim, Ki-Hong; Jeong, Eun-Ju; Chang, Won-Seok; Kim, Jong-Ki

    2012-03-01

    In order to study potent microenvironments of malignant gliomas with a high- resolution x-ray imaging technique, an injection orthotopic glioma model was made using the Sprague-Dawley rat. Total brain tissue, taken out as an ex vivo model, was examined with diffraction-enhanced imaging (DEI) computed tomography (CT) acquired with a 35 keV monochromatic x-ray. In the convolution-reconstructed 2D/3D images with a spatial resolution of 12.5 × 12.5 × 25 µm, distinction among necrosis, typical ring-shaped viable tumors, edemas and healthy tissues was clearly observed near the frontal lobe in front of the rat's caudate nucleus. Multiple microvascular proliferations (MVPs) were observed surrounding peritumoral edemas as a tumor infiltration structure. Typical dimensions of tubular MVPs were 130 (diameter) ×250 (length) µm with a partial sprout structure revealed in the 3D reconstructed image. Hyperplasia of cells around vessel walls was revealed with tumor cell infiltration along the perivascular space in microscopic observations of mild MVP during histological analysis. In conclusion, DEI-CT is capable of imaging potent tumor-infiltrating MVP structures surrounding high-grade gliomas.

  5. Structural, mechanical and electronic properties of in-plane 1T/2H phase interface of MoS{sub 2} heterostructures

    SciTech Connect

    Guo, Xiaoyan; Yang, Guohui; Zhang, Junfeng; Xu, Xiaohong

    2015-09-15

    Two-dimensional (2D) molybdenum disulfide (MoS{sub 2}) phase hybrid system composed by 2H and 1T phase is a natural metal/semiconductor heterostructures and promised a wide range of potential applications. Here, we report the first principle investigations on the structural, mechanical and electronic properties of hybrid system with armchair (AC) and zigzag (ZZ) interfaces. The ZZ type 1T/2H interface are more energy favorable than AC type interface with 3.39 eV/nm. Similar with that of bulked 1T MoS{sub 2}, the intrinsic strengths of the heterostructures are lower than that of the bulk 2H, especially for that with ZZ interface. Analysis of density of states shows that the electronic properties gradually transmitted from the metallic 1T phase to the semiconducting 2H phase for the structural abrupt interface. The present theoretical results constitute a useful picture for the 2D electronic devices using current MoS{sub 2} 1T/2H heterostructures and provide vital insights into the other 2D hybrid materials.

  6. Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates Pr x Y1-x Fe3(BO3)4: magnetic properties and crystal field calculations.

    PubMed

    Pankrats, A I; Demidov, A A; Ritter, C; Velikanov, D A; Semenov, S V; Tugarinov, V I; Temerov, V L; Gudim, I A

    2016-10-01

    The magnetic structure of the mixed rare-earth system Pr x Y1-x Fe3(BO3)4 (x  =  0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x  =  0.67 ÷ 0.45. In the compounds with x  =  0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field. An approach based on a crystal field model for the Pr(3+) ion and the molecular-field approximation is used to describe the magnetic characteristics of the system Pr x Y1-x Fe3(BO3)4. With the parameters of the d-d and f-d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2-300 K). PMID:27478162

  7. Plane Transformations in a Complex Setting I: Homotheties-Translations

    ERIC Educational Resources Information Center

    Dana-Picard, T.

    2006-01-01

    A previous note described how complex numbers can be used for elementary analytic geometry in the plane, describing lines, circles and their intersections using complex Cartesian equations. In the present note, a description of elementary plane transformations, namely homotheties and translations, their group structure and their operations on…

  8. SAS-2 gamma-ray results from the galactic plane and their implications for galactic structure and galactic cosmic-ray dynamics

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.; Thompson, D. J.

    1977-01-01

    The final SAS-2 results related to high energy galactic gamma-ray emission show a strong correlation with galactic structural features seen at other wavelenghts, when the known gamma-ray sources are subtracted. Theoretical considerations and analysis of the gamma-ray data suggest that the galactic cosmic rays are dynamically coupled to the interstellar matter through the magnetic fields, and hence the cosmic ray density is enhanced where the matter density is greatest on the scale of the galactic arms. This concept has been explored in a galactic model that assumes: (1) cosmic rays are galactic and not universal; (2)on the scale of the galactic arms, the cosmic ray column (surface) density is proportional to the total interstellar gas column density; (3)the cosmic ray scale height is significantly larger than the scale height to the matter; and (4) ours is a spiral galaxy characterized by an arm to interarm density ratio of over 2:1.

  9. Plane Smoothers for Multiblock Grids: Computational Aspects

    NASA Technical Reports Server (NTRS)

    Llorente, Ignacio M.; Diskin, Boris; Melson, N. Duane

    1999-01-01

    Standard multigrid methods are not well suited for problems with anisotropic discrete operators, which can occur, for example, on grids that are stretched in order to resolve a boundary layer. One of the most efficient approaches to yield robust methods is the combination of standard coarsening with alternating-direction plane relaxation in the three dimensions. However, this approach may be difficult to implement in codes with multiblock structured grids because there may be no natural definition of global lines or planes. This inherent obstacle limits the range of an implicit smoother to only the portion of the computational domain in the current block. This report studies in detail, both numerically and analytically, the behavior of blockwise plane smoothers in order to provide guidance to engineers who use block-structured grids. The results obtained so far show alternating-direction plane smoothers to be very robust, even on multiblock grids. In common computational fluid dynamics multiblock simulations, where the number of subdomains crossed by the line of a strong anisotropy is low (up to four), textbook multigrid convergence rates can be obtained with a small overlap of cells between neighboring blocks.

  10. The structural and in-plane dielectric/ferroelectric properties of the epitaxial (Ba, Sr)(Zr, Ti)O{sub 3} thin films

    SciTech Connect

    Chan, N. Y. Wang, Y.; Chan, H. L. W.; Wang, D. Y.; Dai, J. Y.

    2014-06-21

    Epitaxial (Ba{sub 1-x}Sr{sub x})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} (BSZT, x = 0 – 0.45) thin films were deposited on (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.35} (LSAT) substrates by pulsed laser deposition. The experimental results demonstrate that the structural, dielectric, and ferroelectric properties of the BSZT thin films were greatly dependent on the strontium content. The BSZT thin films transformed from tetragonal to cubic phase when x ≥ 0.35 at room temperature. The Curie temperature and room-temperature remnant polarization decrease with increasing strontium concentration. The optimal dielectric properties were found in (Ba{sub 0.55}Sr{sub 0.45})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} thin films which is in paraelectric state, having tunability of 47% and loss tangent of 0.0338 under an electric field of 20 MV/m at 1 MHz. This suggests that BSZT thin film is a promising candidate for tunable microwave device applications.

  11. Galactic plane gamma-radiation

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  12. Effects of Growth Temperature on Structural and Electrical Properties of InAlN/GaN Heterostructures Grown by Pulsed Metal Organic Chemical Vapor Deposition on c-Plane Sapphire

    NASA Astrophysics Data System (ADS)

    Xue, JunShuai; Zhang, JinCheng; Hao, Yue

    2013-08-01

    The authors report the effects of growth temperature on the structural and electrical properties of InAlN/GaN heterostructures, which were grown on c-plane sapphire substrates by pulsed metal organic chemical vapor deposition (PMOCVD). High resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM) measurements indicate that the quality of InAlN barrier is strongly dependent on the growth temperature. It is observed that the indium composition and surface root-mean-square (rms) roughness value of InAlN barrier decrease with increasing the growth temperature, and a nearly lattice-matched InAlN/GaN heterostructure with a smooth surface is obtained at 710 °C. As a consequence, the variation of structural properties of InAlN barrier influences the electrical properties of InAlN/GaN heterostructures, and high electron mobility in excess of 1400 cm2 V-1 s-1 is achieved at an optimized growth temperature window of InAlN barrier layer between 710 and 730 °C.

  13. Dynamically variable negative stiffness structures

    PubMed Central

    Churchill, Christopher B.; Shahan, David W.; Smith, Sloan P.; Keefe, Andrew C.; McKnight, Geoffrey P.

    2016-01-01

    Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness–based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators. PMID:26989771

  14. Dynamically variable negative stiffness structures.

    PubMed

    Churchill, Christopher B; Shahan, David W; Smith, Sloan P; Keefe, Andrew C; McKnight, Geoffrey P

    2016-02-01

    Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness-based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators. PMID:26989771

  15. National Aerospace Plane (NASP) program

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Artists concept of the X-30 aerospace plane flying through Earth's atmosphere on its way to low-Earth orbit. the experimental concept is part of the National Aero-Space Plane Program. The X-30 is planned to demonstrate the technology for airbreathing space launch and hypersonic cruise vehicles. Photograph and caption published in Winds of Change, 75th Anniversary NASA publication (page 117), by James Schultz.

  16. The solar system's invariable plane

    NASA Astrophysics Data System (ADS)

    Souami, D.; Souchay, J.

    2012-07-01

    Context. The dynamics of solar system objects, such as dwarf planets and asteroids, has become a well-established field of celestial mechanics in the past thirty years, owing to the improvements that have been made in observational techniques and numerical studies. In general, the ecliptic is taken as the reference plane in these studies, although there is no dynamical reason for doing so. In contrast, the invariable plane as originally defined by Laplace, seems to be a far more natural choice. In this context, the latest study of this plane dates back to Burkhardt. Aims: We define and determine the orientation of the invariable plane of the solar system with respect to both the ICRF and the equinox-ecliptic of J2000.0, and evaluate the accuracy of our determination. Methods: Using the long-term numerical ephemerides DE405, DE406, and INPOP10a over their entire available time span, we computed the total angular momentum of the solar system, as well as the individual contribution to it made by each of the planets, the dwarf planets Pluto and Ceres, and the two asteroids Pallas and Vesta. We then deduced the orientation of the invariable plane from these ephemerides. Results: We update the previous results on the determination of the orientation of the invariable plane with more accurate data, and a more complete analysis of the problem, taking into account the effect of the dwarf planet (1) Ceres as well as two of the biggest asteroids, (4) Vesta and (2) Pallas. We show that the inclusion of these last three bodies significantly improves the accuracy of determination of the invariable plane, whose orientation over a 100 y interval does not vary more than 0.1 mas in inclination, and 0.3 mas in longitude of the ascending node. Moreover, we determine the individual contributions of each body to the total angular momentum of the solar system, as well as the inclination and longitude of the node with respect to this latter plane. Conclusions: Owing to the high accuracy

  17. Peptidoglycan architecture can specify division planes in Staphylococcus aureus.

    PubMed

    Turner, Robert D; Ratcliffe, Emma C; Wheeler, Richard; Golestanian, Ramin; Hobbs, Jamie K; Foster, Simon J

    2010-01-01

    Division in Staphylococci occurs equatorially and on specific sequentially orthogonal planes in three dimensions, resulting, after incomplete cell separation, in the 'bunch of grapes' cluster organization that defines the genus. The shape of Staphylococci is principally maintained by peptidoglycan. In this study, we use Atomic Force Microscopy (AFM) and fluorescence microscopy with vancomycin labelling to examine purified peptidoglycan architecture and its dynamics in Staphylococcus aureus and correlate these with the cell cycle. At the presumptive septum, cells were found to form a large belt of peptidoglycan in the division plane before the centripetal formation of the septal disc; this often had a 'piecrust' texture. After division, the structures remain as orthogonal ribs, encoding the location of past division planes in the cell wall. We propose that this epigenetic information is used to enable S. aureus to divide in sequentially orthogonal planes, explaining how a spherical organism can maintain division plane localization with fidelity over many generations. PMID:20975691

  18. Improvements of the Focal Plane of SASSYER

    NASA Astrophysics Data System (ADS)

    Crump, Danielle; Heinz, Andreas; Winkler, Ryan; Frank, Daniel; Qian, Jing; Fetea, Mirela

    2007-10-01

    The Small Angle Separator System at Yale for Evaporation Residues (SASSYER) at Yale University is a gas-filled recoil separator, specializing in the investigation of the production and the structure of nuclei heavier than ^208Pb. New instrumentation for the focal plane of SASSYER under development at WNSL at Yale will replace the previous equipment with a compact chamber for double-sided silicon detectors (DSSD). Here we are reporting on improvements of the focal plane of SASSYER, including DSSD electronics, a detector cooling system, and ion optics tests. MUX-16 boards from MESYTEC, 16 channel multiplexed amplifiers, were tested and quantified. An alcohol cooling system, related to the DSSD, was characterized. The ion optics tests extracted effective magnetic rigidities of the separator. Results of the tests will be presented. This work was supported by the NSF grant PHY 0555665, Jeffress Fund J-809, and USDOE grant DE-FG02-91ER-40609.

  19. Helicoidal plane of dental occlusion.

    PubMed

    Osborn, J W

    1982-03-01

    A helicoidal plane of postcanine occlusion has been patchily reported in many recent and fossil dentitions of man, and has been suggested as a taxonomic marker distinguishing between the dentitions of Homo and Australopithecines. The present paper describes the helicoidal plane in 19 out of 23 modern human (probably Indian) worn dentitions, in both gracile and robust Australopithecines and in extant anthropoids. It is suggested that tooth wear converts the plane of occlusion present in little-worn teeth, the Monson curve, into a helicoidal plane when 1) the diet is more abrasive, 2) the enamel is thinner and less abrasion resistant, and 3) a longer time separates the eruption of the three molar teeth in a jaw quadrant. A model demonstrates that during the power stroke of a chewing cycle the working side molars move in much the same direction whether the molar occlusal plan follows a Monson curve or a helicoidal plane. The difference is that in the former case the three molars work at the same time while in the latter case they work in sequence from anterior to posterior, thereby concentrating force on one tooth at a time. Because the occlusal plane changes during the life of individuals consuming an abrasive diet, the condition of most anthropoids and hominids, it is argued that the Monson curve has functional significance not because of its influence on occlusal relations and/or jaw movement but because the molar teeth are embedded in bone roughly perpendicular to it, a direction which resists tilting of the teeth during mastication. It is concluded that the helicoidal plane probably has little if any value as a taxonomic marker.

  20. Surface anatomy and anatomical planes in the adult turkish population.

    PubMed

    Uzun, C; Atman, E D; Ustuner, E; Mirjalili, S A; Oztuna, D; Esmer, T S

    2016-03-01

    Surface anatomy and anatomical planes are widely used in education and clinical practice. The planes are largely derived from cadaveric studies and their projections on the skin show discrepancies between and within anatomical reference textbooks. In this study, we reassessed the accuracy of common thoracic and abdominopelvic anatomical planes using computed tomography (CT) imaging in the live adult Turkish population. After patients with distorting pathologies had been excluded, CT images of 150 supine patients at the end tidal inspiration were analyzed. Sternal angle, transpyloric, subcostal, supracristal and pubic crest planes and their relationships to anatomical structures were established by dual consensus. The tracheal bifurcation, azygos vein/superior vena cava (SVC) junction and pulmonary bifurcation were usually below the sternal angle while the concavity of the aortic arch was generally within the plane. The tip of the tenth rib, the superior mesenteric artery and the portal vein were usually within the transpyloric plane while the renal hila and the fundus of the gallbladder were below it. The inferior mesenteric artery was below the subcostal plane and the aortic bifurcation was below the supracristal plane in most adults. Projectional surface anatomy is fundamental to medical education and clinical practice. Modern cross-sectional imaging techniques allow large groups of live patients to be examined. Classic textbook information regarding anatomy needs to be reviewed and updated using the data gathered from these recent studies, taking ethnic differences into consideration.

  1. The Laplace Planes of Uranus and Pluto

    NASA Technical Reports Server (NTRS)

    Dobrovolskis, Anthony R.

    1993-01-01

    Satellite orbits close to an oblate planet precess about its equatorial plane, while distant satellites precess around the plane of the planet's heliocentric orbit. In between, satellites in nearly circular orbits precess about a warped intermediate surface called the Laplace 'plane.' Herein we derive general formulas for locating the Laplace plane. Because Uranus and Pluto have high obliquities, their Laplace planes are severely warped. We present maps of these Laplace planes, of interest in telescopic searches for new satellites. The Laplace plane of the Solar System as a whole is similarly distorted, but comets in the inner Oort cloud precess too slowly to sense the Laplace plane.

  2. Concentric Nested Toroidal Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2010-01-01

    Assemblies comprising multiple limited- height toroidal inflatable structures nested in a concentric arrangement have been invented to obtain more design flexibility than can be obtained in single taller, wider toroidal inflatable structures (see figure). Originally intended for use as containers for habitats for humans in outer space or on remote planets, these and related prior inflatable structures could also be useful on Earth as lightweight, compactly stowable, portable special-purpose buildings that could be transported to remote locations and there inflated to full size and shape. In the case of a single inflatable toroidal structure, one important source of lack of design flexibility is the fact that an increase in outer diameter (which is sometimes desired) is necessarily accompanied by an increase in height (which is sometimes undesired). Increases in diameter and height can also cause difficulty in utilization of the resulting larger volume, in that it can become necessary to partition the volume by means of walls and floors, and features (e.g., stairs or ladders) must be added to enable vertical movement between floors. Moreover, ascending and descending between floors in a gravitational environment could pose unacceptable difficulty for the inhabitants under some circumstances. Another source of lack of design flexibility in a single toroidal inflatable structure is that for a given inflation pressure, an increase in the outer diameter of the structure necessarily entails an increase in the maximum stress in the structure. Because it is necessary to keep the maximum stress within the load-bearing capability of the structural materials, consistent with other aspects of the design, this may translate to a limit on the outer diameter. In an assembly comprising concentric nested toroidal structures, an increase in outer diameter does not necessarily entail an increase in height or a maximum stress in excess of the load-bearing capability of the structural

  3. Explosive plane-wave lens

    DOEpatents

    Marsh, S.P.

    1988-03-08

    An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 4 figs.

  4. Explosive plane-wave lens

    DOEpatents

    Marsh, Stanley P.

    1988-01-01

    An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive.

  5. Explosive plane-wave lens

    DOEpatents

    Marsh, S.P.

    1987-03-12

    An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 3 figs., 3 tabs.

  6. Plane waves as tractor beams

    NASA Astrophysics Data System (ADS)

    Forgács, Péter; Lukács, Árpád; Romańczukiewicz, Tomasz

    2013-12-01

    It is shown that in a large class of systems, plane waves act as tractor beams: i.e., an incident plane wave can exert a pulling force on the scatterer. The underlying physical mechanism for the pulling force is due to the sufficiently strong scattering of the incoming wave into another mode carrying more momentum, in which case excess momentum is created behind the scatterer. This tractor beam or negative radiation pressure (NRP) effect, is found to be generic in systems with multiple scattering channels. In a birefringent medium, electromagnetic plane waves incident on a thin plate exert NRP of the same order of magnitude as optical radiation pressure, while in artificial dielectrics (metamaterials), the magnitude of NRP can even be macroscopic. In two dimensions, we study various scattering situations on vortices, and NRP is shown to occur by the scattering of heavy baryons into light leptons off cosmic strings, and by neutron scattering off vortices in the XY model.

  7. In-plane propagation of electromagnetic waves in planar metamaterials

    NASA Astrophysics Data System (ADS)

    Yi, Changhyun; Rhee, Joo Yull; Kim, Ki Won; Lee, YoungPak

    2016-08-01

    Some planar metamaterials (MMs) or subwavelength antenna/hole arrays have a considerable amount of in-plane propagation when certain conditions are met. In this paper, the in-plane propagation caused by a wave incident on a MM absorber was studied by using a finite-difference time-domain (FDTD) technique. By using a FDTD simulation, we were able to observe a nonnegligible amount of in-plane propagation after the incident wave had arrived at the surface of the planar structure and gradually decreased propagation of the electromagnetic wave in the planar direction gradually decreased. We performed the FDTD simulation carefully to reproduce valid results and to verify the existence of in-plane propagation. For verification of the in-plane propagation explicitly, Poynting vectors were calculated and visualized inside the dielectric substrate between the metallic back-plate and an array of square patches. We also investigated several different structures with resonators of various shapes and found that the amount of facing edges of adjacent metallic patches critically determined the strength of the in-plane propagation. Through this study, we could establish the basis for the existence of in-plane propagation in MMs.

  8. Radiation enhanced basal plane dislocation glide in GaN

    NASA Astrophysics Data System (ADS)

    Yakimov, Eugene B.; Vergeles, Pavel S.; Polyakov, Alexander Y.; Lee, In-Hwan; Pearton, Stephen J.

    2016-05-01

    A movement of basal plane segments of dislocations in GaN films grown by epitaxial lateral overgrowth under low energy electron beam irradiation (LEEBI) was studied by the electron beam induced current (EBIC) method. Only a small fraction of the basal plane dislocation segments were susceptible to irradiation and the movement was limited to relatively short distances. The effect is explained by the radiation enhanced dislocation glide (REDG) in the structure with strong pinning. A dislocation velocity under LEEBI with a beam current lower than 1 nA was estimated as about 10 nm/s. The results assuming the REDG for prismatic plane dislocations were presented.

  9. Two Planes of Satellites in the Centaurus A Group

    NASA Astrophysics Data System (ADS)

    Tully, R. Brent; Libeskind, Noam I.; Karachentsev, Igor D.; Karachentseva, Valentina E.; Rizzi, Luca; Shaya, Edward J.

    2015-04-01

    Tip of the red giant branch measurements based on Hubble Space Telescope and ground-based imaging have resulted in accurate distances to 29 galaxies in the nearby Centaurus A Group. All but 2 of the 29 galaxies lie in either of two thin planes roughly parallel with the supergalactic equator. The planes are only slightly tilted from the line of sight, leaving little ambiguity regarding the morphology of the structure. The planes have characteristic rms long axis dimensions of ∼300 kpc and short axis dimensions of ∼60 kpc, hence axial ratios ∼0.2, and are separated in the short axis direction by 303 kpc.

  10. Plane waves in noncommutative fluids

    NASA Astrophysics Data System (ADS)

    Abdalla, M. C. B.; Holender, L.; Santos, M. A.; Vancea, I. V.

    2013-08-01

    We study the dynamics of the noncommutative fluid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monochromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy-momentum tensor of the plane waves is calculated.

  11. Space-Plane Spreadsheet Program

    NASA Technical Reports Server (NTRS)

    Mackall, Dale

    1993-01-01

    Basic Hypersonic Data and Equations (HYPERDATA) spreadsheet computer program provides data gained from three analyses of performance of space plane. Equations used to perform analyses derived from Newton's second law of physics, derivation included. First analysis is parametric study of some basic factors affecting ability of space plane to reach orbit. Second includes calculation of thickness of spherical fuel tank. Third produces ratio between volume of fuel and total mass for each of various aircraft. HYPERDATA intended for use on Macintosh(R) series computers running Microsoft Excel 3.0.

  12. Two Polymorphic Forms of a Six-Coordinate Mononuclear Cobalt(II) Complex with Easy-Plane Anisotropy: Structural Features, Theoretical Calculations, and Field-Induced Slow Relaxation of the Magnetization.

    PubMed

    Roy, Subhadip; Oyarzabal, Itziar; Vallejo, Julia; Cano, Joan; Colacio, Enrique; Bauza, Antonio; Frontera, Antonio; Kirillov, Alexander M; Drew, Michael G B; Das, Subrata

    2016-09-01

    A mononuclear cobalt(II) complex [Co(3,5-dnb)2(py)2(H2O)2] {3,5-Hdnb = 3,5-dinitrobenzoic acid; py = pyridine} was isolated in two polymorphs, in space groups C2/c (1) and P21/c (2). Single-crystal X-ray diffraction analyses reveal that 1 and 2 are not isostructural in spite of having equal formulas and ligand connectivity. In both structures, the Co(II) centers adopt octahedral {CoN2O4} geometries filled by pairs of mutually trans terminal 3,5-dnb, py, and water ligands. However, the structures of 1 and 2 disclose distinct packing patterns driven by strong intermolecular O-H···O hydrogen bonds, leading to their 0D→2D (1) or 0D→1D (2) extension. The resulting two-dimensional layers and one-dimensional chains were topologically classified as the sql and 2C1 underlying nets, respectively. By means of DFT theoretical calculations, the energy variations between the polymorphs were estimated, and the binding energies associated with the noncovalent interactions observed in the crystal structures were also evaluated. The study of the direct-current magnetic properties, as well as ab initio calculations, reveal that both 1 and 2 present a strong easy-plane magnetic anisotropy (D > 0), which is larger for the latter polymorph (D is found to exhibit values between +58 and 117 cm(-1) depending on the method). Alternating current dynamic susceptibility measurements show that these polymorphs exhibit field-induced slow relaxation of the magnetization with Ueff values of 19.5 and 21.1 cm(-1) for 1 and 2, respectively. The analysis of the whole magnetic data allows the conclusion that the magnetization relaxation in these polymorphs mainly takes place through a virtual excited state (Raman process). It is worth noting that despite the notable difference between the supramolecular networks of 1 and 2, they exhibit almost identical magnetization dynamics. This fact suggests that the relaxation process is intramolecular in nature and that the virtual state involved in the

  13. Two Polymorphic Forms of a Six-Coordinate Mononuclear Cobalt(II) Complex with Easy-Plane Anisotropy: Structural Features, Theoretical Calculations, and Field-Induced Slow Relaxation of the Magnetization.

    PubMed

    Roy, Subhadip; Oyarzabal, Itziar; Vallejo, Julia; Cano, Joan; Colacio, Enrique; Bauza, Antonio; Frontera, Antonio; Kirillov, Alexander M; Drew, Michael G B; Das, Subrata

    2016-09-01

    A mononuclear cobalt(II) complex [Co(3,5-dnb)2(py)2(H2O)2] {3,5-Hdnb = 3,5-dinitrobenzoic acid; py = pyridine} was isolated in two polymorphs, in space groups C2/c (1) and P21/c (2). Single-crystal X-ray diffraction analyses reveal that 1 and 2 are not isostructural in spite of having equal formulas and ligand connectivity. In both structures, the Co(II) centers adopt octahedral {CoN2O4} geometries filled by pairs of mutually trans terminal 3,5-dnb, py, and water ligands. However, the structures of 1 and 2 disclose distinct packing patterns driven by strong intermolecular O-H···O hydrogen bonds, leading to their 0D→2D (1) or 0D→1D (2) extension. The resulting two-dimensional layers and one-dimensional chains were topologically classified as the sql and 2C1 underlying nets, respectively. By means of DFT theoretical calculations, the energy variations between the polymorphs were estimated, and the binding energies associated with the noncovalent interactions observed in the crystal structures were also evaluated. The study of the direct-current magnetic properties, as well as ab initio calculations, reveal that both 1 and 2 present a strong easy-plane magnetic anisotropy (D > 0), which is larger for the latter polymorph (D is found to exhibit values between +58 and 117 cm(-1) depending on the method). Alternating current dynamic susceptibility measurements show that these polymorphs exhibit field-induced slow relaxation of the magnetization with Ueff values of 19.5 and 21.1 cm(-1) for 1 and 2, respectively. The analysis of the whole magnetic data allows the conclusion that the magnetization relaxation in these polymorphs mainly takes place through a virtual excited state (Raman process). It is worth noting that despite the notable difference between the supramolecular networks of 1 and 2, they exhibit almost identical magnetization dynamics. This fact suggests that the relaxation process is intramolecular in nature and that the virtual state involved in the

  14. Plane-wave expansion of elliptic cylindrical functions

    NASA Astrophysics Data System (ADS)

    Santini, Carlo; Frezza, Fabrizio; Tedeschi, Nicola

    2015-08-01

    Elliptic Cylindrical Waves (ECW), defined as the product of an angular Mathieu function by its corresponding radial Mathieu function, occur in the solution of scattering problems involving two-dimensional structures with elliptic cross sections. In this paper, we explicitly derive the expansion of ECW, along a plane surface, in terms of homogeneous and evanescent plane waves, showing the accuracy of the numerical implementation of the formulas and discussing possible applications of the result.

  15. Affine Contractions on the Plane

    ERIC Educational Resources Information Center

    Celik, D.; Ozdemir, Y.; Ureyen, M.

    2007-01-01

    Contractions play a considerable role in the theory of fractals. However, it is not easy to find contractions which are not similitudes. In this study, it is shown by counter examples that an affine transformation of the plane carrying a given triangle onto another triangle may not be a contraction even if it contracts edges, heights or medians.…

  16. Braiding patterns on an inclined plane.

    PubMed

    Mertens, Keith; Putkaradze, Vakhtang; Vorobieff, Peter

    2004-07-01

    A jet of fluid flowing down a partially wetting, inclined plane usually meanders but--by maintaining a constant flow rate--meandering can be suppressed, leading to the emergence of a beautiful braided structure. Here we show that this flow pattern can be explained by the interplay between surface tension, which tends to narrow the jet, and fluid inertia, which drives the jet to widen. These observations dispel misconceptions about the relationship between braiding and meandering that have persisted for over 20 years.

  17. Apparatus for integrating a rigid structure into a flexible wall of an inflatable structure

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor); Patterson, Ross M. (Inventor); Spexarth, Gary R. (Inventor)

    2009-01-01

    For an inflatable structure having a flexible outer shell or wall structure having a flexible restraint layer comprising interwoven, load-bearing straps, apparatus for integrating one or more substantially rigid members into the flexible shell. For each rigid member, a corresponding opening is formed through the flexible shell for receiving the rigid member. A plurality of connection devices are mounted on the rigid member for receiving respective ones of the load-bearing straps. In one embodiment, the connection devices comprise inner connecting mechanisms and outer connecting mechanisms, the inner and outer connecting mechanisms being mounted on the substantially rigid structure and spaced along a peripheral edge portion of the structure in an interleafed array in which respective outer connecting mechanisms are interposed between adjacent pairs of inner connecting mechanisms, the outer connecting mechanisms projecting outwardly from the peripheral edge portion of the substantially rigid structure beyond the adjacent inner connecting mechanisms to form a staggered array of connecting mechanisms extending along the panel structure edge portion. In one embodiment, the inner and outer connecting mechanisms form part of an integrated, structure rotatably mounted on the rigid member peripheral edge portion.

  18. Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

    PubMed Central

    Ficanha, Evandro Maicon; Ribeiro, Guilherme Aramizo; Rastgaar, Mohammad

    2015-01-01

    This paper describes the protocols and results of the experiments for the estimation of the mechanical impedance of the humans’ lower leg in the External–Internal direction in the transverse plane under non-load bearing condition and with relaxed muscles. The objectives of the estimation of the lower leg’s mechanical impedance are to facilitate the design of passive and active prostheses with mechanical characteristics similar to the humans’ lower leg, and to define a reference that can be compared to the values from the patients suffering from spasticity. The experiments were performed with 10 unimpaired male subjects using a lower extremity rehabilitation robot (Anklebot, Interactive Motion Technologies, Inc.) capable of applying torque perturbations to the foot. The subjects were in a seated position, and the Anklebot recorded the applied torques and the resulting angular movement of the lower leg. In this configuration, the recorded dynamics are due mainly to the rotations of the ankle’s talocrural and the subtalar joints, and any contribution of the tibiofibular joints and knee joint. The dynamic mechanical impedance of the lower leg was estimated in the frequency domain with an average coherence of 0.92 within the frequency range of 0–30 Hz, showing a linear correlation between the displacement and the torques within this frequency range under the conditions of the experiment. The mean magnitude of the stiffness of the lower leg (the impedance magnitude averaged in the range of 0–1 Hz) was determined as 4.9 ± 0.74 Nm/rad. The direct estimation of the quasi-static stiffness of the lower leg results in the mean value of 5.8 ± 0.81 Nm/rad. An analysis of variance shows that the estimated values for the stiffness from the two experiments are not statistically different. PMID:26697424

  19. Mechanical Impedance of the Non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane.

    PubMed

    Ficanha, Evandro Maicon; Ribeiro, Guilherme Aramizo; Rastgaar, Mohammad

    2015-01-01

    This paper describes the protocols and results of the experiments for the estimation of the mechanical impedance of the humans' lower leg in the External-Internal direction in the transverse plane under non-load bearing condition and with relaxed muscles. The objectives of the estimation of the lower leg's mechanical impedance are to facilitate the design of passive and active prostheses with mechanical characteristics similar to the humans' lower leg, and to define a reference that can be compared to the values from the patients suffering from spasticity. The experiments were performed with 10 unimpaired male subjects using a lower extremity rehabilitation robot (Anklebot, Interactive Motion Technologies, Inc.) capable of applying torque perturbations to the foot. The subjects were in a seated position, and the Anklebot recorded the applied torques and the resulting angular movement of the lower leg. In this configuration, the recorded dynamics are due mainly to the rotations of the ankle's talocrural and the subtalar joints, and any contribution of the tibiofibular joints and knee joint. The dynamic mechanical impedance of the lower leg was estimated in the frequency domain with an average coherence of 0.92 within the frequency range of 0-30 Hz, showing a linear correlation between the displacement and the torques within this frequency range under the conditions of the experiment. The mean magnitude of the stiffness of the lower leg (the impedance magnitude averaged in the range of 0-1 Hz) was determined as 4.9 ± 0.74 Nm/rad. The direct estimation of the quasi-static stiffness of the lower leg results in the mean value of 5.8 ± 0.81 Nm/rad. An analysis of variance shows that the estimated values for the stiffness from the two experiments are not statistically different.

  20. Epitaxial growth, electrical and optical properties of a-plane InN on r-plane sapphire

    SciTech Connect

    Ajagunna, A. O.; Iliopoulos, E.; Tsiakatouras, G.; Tsagaraki, K.; Androulidaki, M.; Georgakilas, A.

    2010-01-15

    The heteroepitaxy of a-plane (1120) InN films on r-plane (1102) sapphire substrates, by nitrogen radio frequency plasma-assisted molecular beam epitaxy, has been investigated and compared to that of c-plane (0001) InN. The epitaxial growth of a-plane InN proceeded through the nucleation, growth, and coalescence of three-dimensional islands, resulting in surface roughness that increased monotonically with epilayer thickness. The full width at half maximum of (1120) x-ray diffraction rocking curves decreased significantly with increasing InN thickness, characteristic of structural improvement, and it reached the value of 24 arcmin for a 1 {mu}m thick film. Hall-effect measurements exhibited a similar dependence of electron concentration and mobility on thickness for both the a- and c-plane InN films. The analysis of the Hall-effect measurements, by considering the contribution of two conducting layers, indicates a similar accumulation of low mobility electrons with N{sub s}>10{sup 14} cm{sup -2} at the films' surface/interfacial region for both the a- and c-plane InN films. From optical transmittance measurements, the absorption edge of 0.768 eV was determined for the 1 {mu}m a-plane film, consistent with the expected Burstein-Moss effect. Photoluminescence spectra exhibited a lower energy peak at 0.631 eV, suggesting defect-related transitions.

  1. Twisted sectors from plane partitions

    NASA Astrophysics Data System (ADS)

    Datta, Shouvik; Gaberdiel, Matthias R.; Li, Wei; Peng, Cheng

    2016-09-01

    Twisted sectors arise naturally in the bosonic higher spin CFTs at their free points, as well as in the associated symmetric orbifolds. We identify the coset representations of the twisted sector states using the description of W_{∞} representations in terms of plane partitions. We confirm these proposals by a microscopic null-vector analysis, and by matching the excitation spectrum of these representations with the orbifold prediction.

  2. A method of plane geometry primitive presentation

    NASA Astrophysics Data System (ADS)

    Jiao, Anbo; Luo, Haibo; Chang, Zheng; Hui, Bin

    2014-11-01

    Point feature and line feature are basic elements in object feature sets, and they play an important role in object matching and recognition. On one hand, point feature is sensitive to noise; on the other hand, there are usually a huge number of point features in an image, which makes it complex for matching. Line feature includes straight line segment and curve. One difficulty in straight line segment matching is the uncertainty of endpoint location, the other is straight line segment fracture problem or short straight line segments joined to form long straight line segment. While for the curve, in addition to the above problems, there is another difficulty in how to quantitatively describe the shape difference between curves. Due to the problems of point feature and line feature, the robustness and accuracy of target description will be affected; in this case, a method of plane geometry primitive presentation is proposed to describe the significant structure of an object. Firstly, two types of primitives are constructed, they are intersecting line primitive and blob primitive. Secondly, a line segment detector (LSD) is applied to detect line segment, and then intersecting line primitive is extracted. Finally, robustness and accuracy of the plane geometry primitive presentation method is studied. This method has a good ability to obtain structural information of the object, even if there is rotation or scale change of the object in the image. Experimental results verify the robustness and accuracy of this method.

  3. MIPAS focal-plane optics

    NASA Astrophysics Data System (ADS)

    Bokhove, Henk; Smorenburg, C.; Visser, H.

    1993-11-01

    The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) has been selected by ESA for the ENVISAT-Mission, scheduled for launch in 1998. The instrument will measure the concentration of a number of atmospheric trace gases in the earth atmosphere in a spectral region from 4.15 - 14.6 micrometers . Within this region measurements are performed with high spectral resolution. The MIPAS optical system consists of scan mirrors, a telescope, a Michelson interferometer, an afocal reducer and a focal plane assembly. TNO Institute of Applied Physics is involved in the design and development of the afocal reducer and the focal plane assembly. The beam reducing optics of the afocal reducer consist of 2 concave and one convex mirror. Both the housing and the mirrors are made of aluminum to ensure temperature invariance. The optics of the focal plane assembly consist of aluminum mirrors, dichroic beamsplitters and Ge lenses in front of the detectors. The optical/mechanical design is developed to the level that phase C2/D activities can start.

  4. SETI in the Ecliptic Plane

    NASA Astrophysics Data System (ADS)

    Conn Henry, Richard; Kilston, S.; Shostak, S.

    2008-05-01

    The strong advantages of SETI searches in the ecliptic plane have been pointed out by Kilston, Shostak, and Henry (2008). In our poster we show one possible history of civilizations in the galaxy, from birth, through galactic colonization, up to death - and even beyond. Should this scenario be correct, the pattern suggests that the best hope for success in SETI is exploration of the possibility that there are a few extremely ancient but non-colonizing civilizations; civilizations that, aeons ago, detected the existence of Earth (oxygen, and hence life) and of its Moon (stabilizing Earth's rotation) via observations of transits of the Sun (hence, ecliptic, which is stable over millions of years [Laskar et al. 2004]), and have been beaming voluminous information in our direction ever since, in their faint hope (now realized) that a technological "receiving” species would appear. To maintain such a targeted broadcast would be extremely cheap for an advanced civilization. A search of a swath centered on our ecliptic plane should easily find such civilizations, if they exist. We hope to carry out such a search, using the Allen Telescope Array. http://henry.pha.jhu.edu/poster.SETI.pdf References: Kilston, Steven; Shostak, Seth; & Henry, Richard Conn; "Who's Looking at You, Kid?: SETI Advantages near the Ecliptic Plane," AbSciCon 2008, April 14-17, Santa Clara, CA.; Laskar, J., et al., A&A 428, 261, 2004 This work was supported by Maryland Space Grant Consortium.

  5. Point-to-plane and plane-to-plane electrostatic charge injection atomization for insulating liquids

    NASA Astrophysics Data System (ADS)

    Malkawi, Ghazi

    An electrostatic charge injection atomizer was fabricated and used to introduce and study the electrostatic charge injection atomization methods for highly viscous vegetable oils and high conductivity low viscosity aviation fuel, JP8. The total, spray and leakage currents and spray breakup characteristics for these liquids were investigated and compared with Diesel fuel data. Jet breakup and spray atomization mechanism showed differences for vegetable oils and lower viscosity hydrocarbon fuels. For vegetable oils, a bending/spinning instability phenomenon was observed similar to the phenomenon found in liquid jets of high viscosity polymer solutions. The spray tip lengths and cone angles were presented qualitatively and quantitatively and correlated with the appropriate empirical formulas. The different stages of the breakup mechanisms for such oils, as a function of specific charges and flow rates, were discussed. In order to make this method of atomization more suitable for practical use in high flow rate applications, a blunt face electrode (plane-to-plane) was used as the charge emitter in place of a single pointed electrode (point-to-plane). This allowed the use of a multi-orifice emitter that maintained a specific charge with the flow rate increase which could not be achieved with the needle electrode. The effect of the nozzle geometry, liquid physical properties and applied bulk flow on the spray charge, total charge, maximum critical spray specific charge and electrical efficiency compared with the needle point-to-plane atomizer results was presented. Our investigation revealed that the electrical efficiency of the atomizer is dominated by the charge forced convection rate rather than charge transport by ion motilities and liquid motion by the electric field. As a result of the electric coulomb forces between the electrified jets, the multi-orifice atomizer provided a unique means of dispersing the fuel in a hollow cone with wide angles making the new

  6. Improved fake mode free plane wave expansion method.

    PubMed

    Jiang, Bin; Zhou, Wenjun; Chen, Wei; Liu, Anjin; Zheng, Wanhua

    2011-08-01

    We analyze the origin of the fake modes introduced by the plane wave expansion method with three-dimension (3D) supercell approximation. Through the detailed analysis of the energy distribution of fake modes and real modes, we propose the plane wave expansion-three planar-slab waveguides method to remove the fake modes and obtain the fake mode free band structure of a two-dimensional air hole photonic crystal slab. To the best of our knowledge, this is the first time that such a fake mode free photonic crystal band structure is presented. Our method is also definitely useful in designing other 3D devices.

  7. Eta Carinae: Orientation of The Orbital Plane

    NASA Technical Reports Server (NTRS)

    Gull, T. R.; Nielsen, K. E.; Ivarsson, S.; Corcoran, M. F.; Verner, E.; Hillier, J. D.

    2006-01-01

    Evidence continues to build that Eta Carinae is a massive binary system with a hidden hot companion in a highly elliptical orbit. We present imaging and spectroscopic evidence that provide clues to the orientation of the orbital plane. The circumstellar ejecta, known as the Homunculus and Little Homunculus, are hourglass-shaped structures, one encapsulated within the other, tilted at about 45 degrees from the sky plane. A disk region lies between the bipolar lobes. Based upon their velocities and proper motions, Weigelt blobs B, C and D, very bright emission clumps 0.1 to 0.3" Northwest from Eta Carinae, lie in the disk. UV flux from the hot companion, Eta Car B, photoexcites the Weigelt blobs. Other clumps form a complete chain around the star, but are not significantly photoexcited. The strontium filament, a 'neutral' emission structure, lies in the same general direction as the Weigelt blobs and exhibits peculiar properties indicative that much mid-UV, but no hydrogen-ionizing radiation impinges on this structure. It is shielded by singly-ionized iron. P Cygni absorptions in Fe I I lines, seen directly in line of sight from Eta Carinae, are absent in the stellar light scattered by the Weigelt blobs. Rather than a strong absorption extending to -600 km/s, a low velocity absorption feature extends from -40 to -150 km/s. No absorbing Fe II exists between Eta Carinae and Weigelt D, but the outer reaches of the wind are intercepted in line of sight from Weigelt D to the observer. This indicates that the UV radiation is constrained by the dominating wind of Eta Car A to a small cavity carved out by the weaker wind of Eta Car B. Since the high excitation nebular lines are seen in the Weigelt blobs at most phases, the cavity, and hence the major axis of the highly elliptical orbit, must lie in the general direction of the Weigelt blobs. The evidence is compelling that the orbital major axis of Eta Carinae is projected at -45 degrees position angle on the sky. Moreover

  8. SNAP Satellite Focal Plane Development

    SciTech Connect

    Bebek, C.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Baltay, C.; Barrelet, E.; Basa, S.; Bercovitz, J.; Bergstrom, L.; Berstein, G.P.; Bester, M.; Bohlin, R.; Bonissent, A.; Bower, C.; Campbell, M.; Carithers, W.; Commins, E.; Day, C.; Deustua, S.; DiGennaro, R.; Ealet, A.; Ellis, R.; Emmett, W.; Eriksson, M.; Fouchez,D.; Fruchter, A.; Genat, J-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Heetderks, H.; Holland, S.; Huterer, D.; Johnson, W.; Kadel, R.; Karcher,A.; Kim, A.; Kolbe, W.; Lafever, R.; Lamoureaux, J.; Lampton, M.; Lefevre, O.; Levi, M.; Levin, D.; Linder, E.; Loken, S.; Malina, R.; Mazure, A.; McKay, T.; McKee, S.; Miquel, R.; Morgan, N.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Roe, N.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Prieto, E.; Rabinowitz,D.; Refregier, A.; Rhodes, J.; Schubnell, M.; Sholl, M.; Smadja, G.; Smith, R.; Smoot, G.; Snyder, J.; Spadafora, A.; Szymkowiak, A.; Tarle,G.; Taylor, K.; Tilquin, A.; Tomasch, A.; Vincent, D.; von der Lippe, H.; Walder, J-P.; Wang, G.

    2003-07-07

    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.

  9. Thermomechanical architecture of the VIS focal plane for Euclid

    NASA Astrophysics Data System (ADS)

    Martignac, Jérôme; Carty, Michaël.; Tourette, Thierry; Bachet, Damien; Berthé, Michel; Augueres, Jean-Louis; Amiaux, Jérôme; Fontignie, Jean; Horeau, Benoît; Renaud, Diana; Pottinger, Sabrina; Denniston, James; Winter, Berend; Guttridge, Phillip; Cole, Richard; Cropper, Mark; Niemi, Sami; Coker, John; Hunt, Thomas

    2014-08-01

    One of the main challenges for current and near future space experiments is the increase of focal plane complexity in terms of amount of pixels. In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. CEA has developed the thermomechanical architecture of that Focal Plane taking into account all the very stringent performance and mission related requirements. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K) as to obtain one of the largest focal plane (˜0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the e2v company under ESA contract, front end electronics is studied and provided by MSSL. In this paper we first recall the specific requirements that have driven the overall architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally. The mechanical structure based on SiC material used for the cold sub assembly supporting the CCDs is detailed. We describe also the modular architecture concept that we have selected taking into account AIT-AIV and programmatic constraints.

  10. Drag reduction at a plane wall

    NASA Technical Reports Server (NTRS)

    Hill, D. C.

    1993-01-01

    The objective is to determine by analytical means how drag on a plane wall may be modified favorably using a minimal amount of flow information - preferably only information at the wall. What quantities should be measured? How should that information be assimilated in order to arrive at effective control? As a prototypical problem, incompressible, viscous flow, governed by the Navier-Stokes equations, past a plane wall at which the no-slip condition was modified was considered. The streamwise and spanwise velocity components are required to be zero, but the normal component is to be specified according to some control law. The challenge is to choose the wall-normal velocity component based on flow conditions at the wall so that the mean drag is as small as possible. There can be no net mass flux through the wall, and the total available control energy is constrained. A turbulent flow is highly unsteady and has detailed spatial structure. The mean drag on the wall is the integral over the wall of the local shear forces exerted by the fluid, which is then averaged in time; it is a 'macroscopic' property of the flow. It is not obvious how unsteady boundary control is to be applied in order to modify the mean flow most effectively, especially in view of the non- self-adjoint nature of the governing equations. An approximate analytical solution to the suboptimal scheme is pursued.

  11. Green's function of the strip-slab guide by plane-wave-spectrum synthesis

    NASA Astrophysics Data System (ADS)

    Sen, T. K.; Basuray, A.; Datta, A. K.

    1987-11-01

    The application of the plane-wave-spectrum method to strip-slab waveguides is described. The dispersion equation of the structure is first evaluated from the condition of self-consistency of rays. By treating the modes as the superpositions of plane waves, Green's function for the structure is subsequently derived.

  12. The Bolocam Galactic Plane Survey

    NASA Technical Reports Server (NTRS)

    Glenn, Jason; Aguirre, James; Bally, John; Battersby, Cara; Bradley, Eric Todd; Cyganowski, Claudia; Dowell, Darren; Drosback, Meredith; Dunham, Miranda K.; Evans, Neal J., II; Ginsburg, Adam; Harvey, Paul; Rosolowsky, Erik; Schlingman, Wayne; Shirley, Yancy L.; Stringfellow, Guy S.; Walawender, Josh; Williams, Jonathan

    2009-01-01

    The Bolocam Galactic Plane Survey (BGPS) is a 1.1 millimeter continuum survey of the northern Galactic Plane made with Bolocam and the Caltech Submillimeter Observatory. The coverage totals 170 square degrees, comprised of a contiguous range from -10.5 deg is less than or equal to 90.5 deg, 0.5 deg is less than or equal to b is less than or equal to 0.5 deg, with extended coverage in b in selected regions, and four targeted regions in the outer Galaxy, including: IC1396, toward the Perseus arm at l is approximately 111 deg, W3/4/5, and Gem OB1. Depths of the maps range from 30 to 60 mJy beam (sup 1). Approximately 8,400 sources were detected and the maps and source catalog have been made publicly available. Millimeter-wave thermal dust emission reveals dense regions within molecular clouds, thus the BGPS serves as a database for studies of the dense interstellar medium and star formation within the Milky Way.

  13. Empirically Derived Strength of Residential Roof Structures for Solar Installations.

    SciTech Connect

    Dwyer, Stephen F.; Sanchez, Alfred; Campos, Ivan A.; Gerstle, Walter H.

    2014-12-01

    Engineering certification for the installation of solar photovoltaic (PV) modules on wood roofs is often denied because existing wood roofs do not meet structural design codes. This work is intended to show that many roofs are actually sufficiently strong given the conservatism in codes, documented allowable strengths, roof structure system effects, and beam composite action produced by joist-sheathing interaction. This report provides results from a testing program to provide actual load carrying capacity of residential rooftops. The results reveal that the actual load carrying capacity of structural members and systems tested are significantly stronger than allowable loads provided by the International Residential Code (IRC 2009) and the national structural code found in Minimum Design Loads for Buildings and Other Structures (ASCE 7-10). Engineering analysis of residential rooftops typically ignores the system affects and beam composite action in determining rooftop stresses given a potential PV installation. This extreme conservatism combined with conservatism in codes and published allowable stress values for roof building materials (NDS 2012) lead to the perception that well built homes may not have adequate load bearing capacity to enable a rooftop PV installation. However, based on the test results presented in this report of residential rooftop structural systems, the actual load bearing capacity is several times higher than published values (NDS 2012).

  14. Crisis bifurcations in plane Poiseuille flow.

    PubMed

    Zammert, Stefan; Eckhardt, Bruno

    2015-04-01

    Many shear flows follow a route to turbulence that has striking similarities to bifurcation scenarios in low-dimensional dynamical systems. Among the bifurcations that appear, crisis bifurcations are important because they cause global transitions between open and closed attractors, or indicate drastic increases in the range of the state space that is covered by the dynamics. We here study exterior and interior crisis bifurcations in direct numerical simulations of transitional plane Poiseuille flow in a mirror-symmetric subspace. We trace the state space dynamics from the appearance of the first three-dimensional exact coherent structures to the transition from an attractor to a chaotic saddle in an exterior crisis. For intermediate Reynolds numbers, the attractor undergoes several interior crises, in which new states appear and intermittent behavior can be observed. The bifurcations contribute to increasing the complexity of the dynamics and to a more dense coverage of state space.

  15. P-Wave and S-Wave Velocity Structure of Submarine Landslide Associated With Gas Hydrate Layer on Frontal Ridge of Northern Cascadia Margin

    NASA Astrophysics Data System (ADS)

    He, T.; Lu, H.; Yelisetti, S.; Spence, G.

    2015-12-01

    The submarine landslide associated with gas hydrate is a potential risk for environment and engineering projects, and thus from long time ago it has been a hot topic of hydrate research. The study target is Slipstream submarine landslide, one of the slope failures observed on the frontal ridges of the Northern Cascadia accretionary margin off Vancouver Island. The previous studies indicated a possible connection between this submarine landslide feature and gas hydrate, whose occurrence is indicated by a prominent bottom-simulating reflector (BSR), at a depth of ~265-275 m beneath the seafloor (mbsf). The OBS (Ocean Bottom Seismometer) data collected during SeaJade (Seafloor Earthquake Array - Japan Canada Cascadia Experiment) project were used to derive the subseafloor velocity structure for both P- and S-wave using travel times picked from refraction and reflection events. The P-wave velocity structure above the BSR showed anomalous high velocities of about 2.0 km/s at shallow depths of 100 mbsf, closely matching the estimated depth of the glide plane (100 ± 10 m). Forward modelling of S-waves was carried out using the data from the OBS horizontal components. The S-wave velocities, interpreted in conjunction with the P-wave results, provide the key constraints on the gas hydrate distribution within the pores. The hydrate distribution in the pores is important for determining concentrations, and also for determining the frame strength which is critical for controlling slope stability of steep frontal ridges. The increase in S-wave velocity suggests that the hydrate is distributed as part of the load-bearing matrix to increase the rigidity of the sediment.

  16. Broken chiral symmetry on a null plane

    SciTech Connect

    Beane, Silas R.

    2013-10-15

    On a null-plane (light-front), all effects of spontaneous chiral symmetry breaking are contained in the three Hamiltonians (dynamical Poincaré generators), while the vacuum state is a chiral invariant. This property is used to give a general proof of Goldstone’s theorem on a null-plane. Focusing on null-plane QCD with N degenerate flavors of light quarks, the chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum condensates is clarified. In particular, the null-plane Gell-Mann–Oakes–Renner formula is derived, and a general prescription is given for mapping all chiral-symmetry breaking QCD condensates to chiral-symmetry conserving null-plane QCD condensates. The utility of the null-plane description lies in the operator algebra that mixes the null-plane Hamiltonians and the chiral symmetry charges. It is demonstrated that in a certain non-trivial limit, the null-plane operator algebra reduces to the symmetry group SU(2N) of the constituent quark model. -- Highlights: •A proof (the first) of Goldstone’s theorem on a null-plane is given. •The puzzle of chiral-symmetry breaking condensates on a null-plane is solved. •The emergence of spin-flavor symmetries in null-plane QCD is demonstrated.

  17. Technologies for the National Aero-Space Plane

    NASA Astrophysics Data System (ADS)

    Rausch, Vincent L.; Morris, Charles E. K., Jr.

    1992-08-01

    Technologies for SSTO and hypersonic atmospheric cruise flight being developed in the context of the National Aero-Space Plane (NASP) program are discussed. Emphasis is given to research in aerothermodynamics, propulsion, fuel technology, structures and materials, vehicle management systems, and CVD and instrumentation tools. Brief attention is also given to the X-30 vehicle and to long-term applications of NASP technologies.

  18. Optimal focal-plane restoration

    NASA Technical Reports Server (NTRS)

    Reichenbach, Stephen E.; Park, Stephen K.

    1989-01-01

    Image restoration can be implemented efficiently by calculating the convolution of the digital image and a small kernel during image acquisition. Processing the image in the focal-plane in this way requires less computation than traditional Fourier-transform-based techniques such as the Wiener filter and constrained least-squares filter. Here, the values of the convolution kernel that yield the restoration with minimum expected mean-square error are determined using a frequency analysis of the end-to-end imaging system. This development accounts for constraints on the size and shape of the spatial kernel and all the components of the imaging system. Simulation results indicate the technique is effective and efficient.

  19. Functional Aesthetic Occlusal Plane (FAOP)

    PubMed Central

    Câmara, Carlos Alexandre; Martins, Renato Parsekian

    2016-01-01

    ABSTRACT Introduction: A reasonable exposure of incisors and gingival tissues is generally considered more attractive than excess or lack of exposure. A reasonable gingival exposure is considered to be around 0 to 2 mm when smiling and 2-4 mm exposure of the maxillary incisor edge when the lips are at rest. Objective: The aim of this paper is to present the Functional Aesthetic Occlusal Plane (FAOP), which aims to help in the diagnosis of the relationships established among molars, incisors and the upper lip. Conclusion: FAOP can complement an existing and established orthodontic treatment plan, facilitating the visualization of functional and aesthetic demands by giving a greater focus on the position of incisors in the relationship established among the incisors, molars and the upper lip stomion. PMID:27653271

  20. Studies of mechanical, themal and fabrication characteristics of multifunctional structural metals

    NASA Astrophysics Data System (ADS)

    Oruganti, Ramkumar K.

    Structural materials, in addition to bearing load, are being sought to perform other functions such as enforcing mechanical compatibility between materials, heat exchange and crash energy absorption. Such needs have led to the development of multifunctional materials, notable among these, and those studied in this research, being compositionally and functionally graded materials (FGM's) and cellular metals. FGM's can be used to reduce thermal expansion mismatch between two materials such as a functional coating and a load-bearing substrate. In such cases, the deformation and creep behavior of the composite interlayers between the two materials becomes of interest. To study this aspect, composites of typical FGM materials, a nickel base superalloy and zirconia, were fabricated by powder metallurgy. It was found that zirconia reacted with Y' (Ni3Al) to form alumina and introduced elemental zirconium and oxygen into the superalloy matrix. These changes resulted in greater strengthening than that expected from composite theory at lower creep rates. At higher creep rates, though, weakening of the composites relative to the original alloy was observed. For the part of research directed toward cellular structures, techniques were developed to fabricate hexagonal honeycomb structures and a bonded woven wire mesh structure. High temperature deformation properties of the honeycomb structures in the transverse (in-plane) direction were investigated. Differences in elastic and anelastic behavior and creep strengths from those observed in solid materials are attributed mainly to the open nature of the structures. Creep in the honeycombs is characterized by cycles of primary, secondary and tertiary stages caused by shear instability in layers of cells. Room temperature tests on the woven wire bonded structure showed sharp yielding in tension but gradual yielding and higher strength in compression. Thermal expansion behavior of some cellular structures was studied since it is of

  1. Thermoelectric characterization and fabrication of nanostructured p-type Bi0.5Sb1.5Te3 and n-type Bi2Te3 thin film thermoelectric energy generator with an in-plane planar structure

    NASA Astrophysics Data System (ADS)

    Park, No-Won; Park, Tae-Hyun; Ahn, Jay-Young; Kang, So-Hyeon; Lee, Won-Yong; Yoon, Young-Gui; Yoon, Soon-Gil; Lee, Sang-Kwon

    2016-06-01

    This paper presents in-plane bismuth-telluride-based thermoelectric (TE) energy generators fabricated using metal-shadow and radio-frequency sputtering methods at room temperature. The TE energy generators consist of four couples of 300-nm-thick nanostructured Bi2Te3 (n-BT) and Bi0.5Sb1.5Te3 (p-BST) thin films used as n-type and p-type materials, respectively, on a Si substrate for the p/n junctions of the TE energy generators. Furthermore, the effect of annealing treatment of both n-BT and p-BST thin films on the electrical and TE properties as well as the TE performance of the TE energy generators is discussed. By varying the temperature between the hot and cold junction legs of the n-BT/p-BST in-plane TE energy generators annealed at 200 °C, the maximum output voltage and power are determined to be ˜3.6 mV and ˜1.1 nW, respectively, at a temperature difference of 50 K. The output powers increased by ˜590% compared to that of the as-grown TE generator at a temperature difference of 90 K. This improvement in the TE performance is attributed to the enhancement of the electrical conductivity after heat treatment. From a numerical simulation conducted using a commercial software (COMSOL), we are confident that it plays a crucial role in determining the dimension (i.e., thickness of each leg) and material properties of both n-BT and p-BST materials of the in-plane TE energy generators.

  2. Artificial impedance ground planes for low profile antenna applications

    NASA Astrophysics Data System (ADS)

    McMichael, Ian T.

    Recent interest in artificial impedance surfaces for low-profile antennas has led to extensive research with the goal of optimizing the ground plane's characteristics for a given antenna configuration and broadening the operational bandwidth, or alternatively creating a multi-band functionality. A method of determining the optimal reflection phase for a low-profile dipole antenna over an electromagnetic band gap (EBG) ground plane has been developed based on image theory and is presented with experimental and numerical validation. A new artificial impedance surface has also been developed, which is composed of an annular slot ring on a thin grounded dielectric. The main difference between the proposed ground plane and a conventional EBG is that the high impedance condition exists only in the vicinity of the slot and is therefore best suited for antennas with a current distribution that has a similar shape as the annular slot ring. It is shown that a loop antenna positioned closely over an annular slot loaded ground plane exhibits approximately the same gain as a loop antenna over a conventional EBG ground plane. The advantage of the new structure is its lack of periodicity, which significantly eases manufacturing. Additionally, it is shown that multiple concentric slot rings can be designed into the ground plane, which excites multiple resonances in low-profile wideband antennas. The result is a multi-band high impedance ground plane constructed using a simple arrangement of annular slots. Finally, a manufacturing technique is presented for the application of arbitrarily configured EBG antennas to handheld dual-sensor landmine detection systems. It is shown that creating an EBG antenna using very thin layers of metal will enable it to be used for ground penetrating radar (GPR) when it is co-located with a low frequency metal detector without compromising the operation of the metal detector. The potential benefit of such an antenna would be a lower profile sensor

  3. The hybrid solution for the Fundamental Plane

    NASA Astrophysics Data System (ADS)

    D'Onofrio, M.; Fasano, G.; Moretti, A.; Marziani, P.; Bindoni, D.; Fritz, J.; Varela, J.; Bettoni, D.; Cava, A.; Poggianti, B.; Gullieuszik, M.; Kjærgaard, P.; Moles, M.; Vulcani, B.; Omizzolo, A.; Couch, W. J.; Dressler, A.

    2013-10-01

    By exploiting the data base of early-type galaxy (ETG) members of the WINGS survey of nearby clusters, we address here the long debated question of the origin and shape of the Fundamental Plane (FP). Our data suggest that different physical mechanisms concur in shaping and `tilting' the FP with respect to the virial plane (VP) expectation. In particular, a `hybrid solution' in which the structure of galaxies and their stellar population are the main contributors to the FP tilt seems to be favoured. We find that the bulk of the tilt should be attributed to structural non-homology, while stellar population effects play an important but less crucial role. In addition, our data indicate that the differential FP tilt between the V and K band is due to a sort of entanglement between structural and stellar population effects, for which the inward steepening of colour profiles (V - K) tends to increase at increasing the stellar mass of ETGs. The same kind of analysis applied to the ATLAS3D and Sloan Digital Sky Survey (SDSS) data in common with WINGS (WSDSS throughout the paper) confirms our results, the only remarkable difference being the less important role that our data attribute to the stellar mass-to-light-ratio (stellar populations) in determining the FP tilt. The ATLAS3D data also suggest that the FP tilt depends as well on the dark matter (DM) fraction and on the rotational contribution to the kinetic energy (Vrot/σ), thus again pointing towards the above-mentioned `hybrid solution'. We show that the global properties of the FP, i.e. its tilt and tightness, can be understood in terms of the underlying correlation among mass, structure and stellar population of ETGs, for which, at increasing the stellar mass, ETGs become (on average) `older' and more centrally concentrated. Finally, we show that a Malmquist-like selection effect may mimic a differential evolution of the mass-to-light ratio for galaxies of different masses. This should be taken into account in the

  4. A differentiated plane wave as an electromagnetic vortex

    NASA Astrophysics Data System (ADS)

    Hannay, J. H.; Nye, J. F.

    2015-04-01

    Differentiating a complex scalar plane wave with respect to its direction produces an isolated straight vortex line and has a natural extension, described in earlier papers, to the vector waves of electromagnetism—a differentiated plane wave (DPW). It epitomizes destructive interference and will be shown to have the local structure of an electromagnetic vortex. In this paper its polarization structure and Poynting vector field are compared and contrasted with that of the family of linear polynomial waves, of which it is a special member. By definition this wider family has a general linear complex vector function of position multiplying a plane wave, but the function must be such that the combination satisfies Maxwell’s equations. This forces translational invariance of the function along the wavevector direction—in other words the wave is ‘non-diffracting’. In a natural sense all possible polarizations are exhibited once only. But the DPW has a distinctive polarization structure only partly explored previously. Both classes of waves share similar Poynting vector fields, which can be ‘elliptic’ (helix-like flow lines) or ‘hyperbolic’, of a repulsive nature, unexpected for a vortex. Both classes can be considered as a limit in the superposition of three closely parallel ordinary plane waves in destructive interference, and this derivation is supplied in full here.

  5. Development and evolution of the helicoidal plane of dental occlusion.

    PubMed

    Smith, B H

    1986-01-01

    The helicoidal plane of dental occlusion is a composite feature involving axial inclination of teeth and effects of dental attrition. Recent studies disagree on its distribution and significance in hominoid primates. The distribution, development, and functional basis of the helicoidal plane are investigated here, based on quantitative analysis of dental morphology and attrition in 667 human and 60 chimpanzee dentitions. Helicoidal planes are nearly universal in the human and chimpanzee dentitions studied. Increasing axial inclination of molars from M1 to M3 is primarily responsible for the helicoidal plane, although attrition acts to increase its expression. In hominoids, increased molar axial tilt appears to be associated with facial shortening and dental reduction. Population and species comparisons suggest a functional relationship with cranial structure. Progressive axial tilt of molars producing a helicoidal plane is found consistently in mammals with cheek teeth positioned partly under the cranium, as in hominids, pongids, some cebids, macropodids, ursids, and sciurids. Facial shortening is an important trend in hominid evolution and axial inclination of molars might be expected to show progressive change from Australopithecus afarensis to recent Homo sapiens. PMID:3080898

  6. A Collaborative Knowledge Plane for Autonomic Networks

    NASA Astrophysics Data System (ADS)

    Mbaye, Maïssa; Krief, Francine

    Autonomic networking aims to give network components self-managing capabilities. Several autonomic architectures have been proposed. Each of these architectures includes sort of a knowledge plane which is very important to mimic an autonomic behavior. Knowledge plane has a central role for self-functions by providing suitable knowledge to equipment and needs to learn new strategies for more accuracy.However, defining knowledge plane's architecture is still a challenge for researchers. Specially, defining the way cognitive supports interact each other in knowledge plane and implementing them. Decision making process depends on these interactions between reasoning and learning parts of knowledge plane. In this paper we propose a knowledge plane's architecture based on machine learning (inductive logic programming) paradigm and situated view to deal with distributed environment. This architecture is focused on two self-functions that include all other self-functions: self-adaptation and self-organization. Study cases are given and implemented.

  7. Duel-Plane Optical Disdrometer

    NASA Astrophysics Data System (ADS)

    Winsky, B. E.; Eichinger, W. E.

    2011-12-01

    Acquiring better drop-size distributions of rainfall will improve our understanding of the spatial and temporal variability of rainfall. In order to fully capture the spatial and temporal variability of rainfall, a robust, calibration free, low-cost instrument that provides an accurate drop-size distribution is required. Therefore, The University of Iowa Lidar Group has developed and built a new duel-plane optical disdrometer that meets these criteria. Two sheets of laser light, vertically spaced by 1 cm are produced by two 670nm laser beams passing through a collecting lens and culminating lens, respectively. The two sheets of laser light then pass through a convex lens located 20 cm from the lasers that focuses the light on a photo detector. A computer reads in and stores the voltages at 10 kHz. The velocity, diameter, shape and drop-size distribution of raindrops are extracted from the voltage measurements. Rainfall data collected in Iowa City, IA tested our disdrometer's robustness and accuracy of providing drop-size distributions. Our distrometer is advantageous because it is simple, low-cost, and requires no calibration.

  8. Radioactivity in the galactic plane

    NASA Technical Reports Server (NTRS)

    Walraven, G. D.; Haymes, R. C.

    1976-01-01

    The paper reports the detection of a large concentration of interstellar radioactivity during balloon-altitude measurements of gamma-ray energy spectra in the band between 0.02 and 12.27 MeV from galactic and extragalactic sources. Enhanced counting rates were observed in three directions towards the plane of the Galaxy; a power-law energy spectrum is computed for one of these directions (designated B 10). A large statistical deviation from the power law in a 1.0-FWHM interval centered near 1.16 MeV is discussed, and the existence of a nuclear gamma-ray line at 1.15 MeV in B 10 is postulated. It is suggested that Ca-44, which emits gamma radiation at 1.156 MeV following the decay of radioactive Sc-44, is a likely candidate for this line, noting that Sc-44 arises from Ti-44 according to explosive models of supernova nucleosynthesis. The 1.16-MeV line flux inferred from the present data is shown to equal the predicted flux for a supernova at a distance of approximately 3 kpc and an age not exceeding about 100 years.

  9. Hubble Views Saturn Ring-Plane Crossing

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This sequence of images from NASA's Hubble Space Telescope documents a rare astronomical alignment -- Saturn's magnificent ring system turned edge-on. This occurs when the Earth passes through Saturn's ring plane, as it does approximately every 15 years.

    These pictures were taken with Hubble's Wide Field Planetary Camera 2 on 22 May 1995, when Saturn was at a distance of 919 million miles (1.5 billion kilometers) from Earth. At Saturn, Hubble can see details as small as 450 miles (725 km) across. In each image, the dark band across Saturn is the ring shadow cast by the Sun which is still 2.7 degrees above Saturn's ring plane. The box around the western portion of the rings (to the right of Saturn) in each image indicates the area in which the faint light from the rings has been multiplied through image processing (by a factor of 25) to make the rings more visible.

    [Top] -

    This image was taken while the Earth was above the lit face of the rings. The moons Tethys and Dione are visible to the east (left) of Saturn; Janus is the bright spot near the center of the ring portion in the box, and Pandora is faintly visible just inside the left edge of this box. Saturn's atmosphere shows remarkable detail: multiple banding in both the northern and southern hemispheres, wispy structure at the north edge of the equatorial zone, and a bright area above the ring shadow that is caused by sunlight scattered off the rings onto the atmosphere. There is evidence of a faint polar haze over the north pole of Saturn and a fainter haze over the south.

    [Center] -

    This image was taken close to the time of ring-plane crossing. The rings are 75% fainter than in the top image, though they do not disappear completely because the vertical face of the rings still reflects sunlight when the rings are edge-on. Rhea is visible to the east of Saturn, Enceladus is the bright satellite in the rings to the west, and Janus is the fainter blip to its right. Pandora is just to the left of

  10. Deployable Soft Composite Structures.

    PubMed

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-01-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel. PMID:26892762

  11. Deployable Soft Composite Structures

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-02-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  12. Deployable Soft Composite Structures

    PubMed Central

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-01-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel. PMID:26892762

  13. Deployable Soft Composite Structures.

    PubMed

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-02-19

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  14. Plane wave spectrum of electromagnetic beams

    NASA Astrophysics Data System (ADS)

    Doicu, A.; Wriedt, T.

    1997-02-01

    A plane wave spectrum method of Gaussian beams can be derived by using Davis' approximations for the vector potential. An equivalent vector potential is introduced by considering the inverse Fourier transform of the spectrum function of the original vector potential in a given plane. The electromagnetic field, which corresponds to the equivalent vector potential, satisfies Maxwell's equations and can be written as a sum of plane waves. The beam shape coefficients, or the expansion coefficients in terms of regular spherical vector wave functions, are expressed as simple integrals. This version of the plane wave spectrum method offers the possibility to compute higher-order corrections for Gaussian beams.

  15. Galactic diffuse gamma rays from galactic plane

    NASA Astrophysics Data System (ADS)

    Tateyama, N.; Nishimura, J.

    2001-08-01

    The dominant part of the diffuse gamma rays from the Galactic plane, with energy greater than 1TeV, has been thought as due to the inverse Compton scattering of the interstellar photons with the high-energy cosmic electrons. In these energy regions, the diffuse gamma-ray observation gives us unique infor-mation on the energy spectrum of the high-energy electrons in the interstellar space, since we cannot observe those electrons directly. This provides us information on the cosmicray source, production mechanism and propagation in the Galaxy. We discuss the implication of our results by comparing with the work of Porter and Protheroe, and also compare with the data observed by the most recent extensive air showers. It is also pointed out that the patchy structure of gammaray distribution will appear at high-energy side, if we observe the distribution with a higher angular resolution of a few arc degrees. This patchy structure will become clear beyond 10TeV of IC gamma rays, where the number of contributing sources of parent decrease and the diffusion distance of the electrons become smaller.

  16. National Aerospace Plane Thermal Development. (Latest Citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning thermal properties of the National Aerospace Plane (NASP). Analysis of thermal stress, and methods for determining thermal effects on the plane's supersonic structure are discussed. The citations also review temperature extremes that the vehicle is likely to encounter. (Contains 50-250 citations and includes a subject term index and title list.)

  17. National Aerospace Plane Thermal Development. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The bibliography contains citations concerning thermal properties of the National Aerospace Plane (NASP). Analysis of thermal stress, and methods for determining thermal effects on the plane's supersonic structure are discussed. The citations also review temperature extremes that the vehicle is likely to encounter.

  18. In-plane Van der Waals interactions of molecular self-assembly monolayer

    NASA Astrophysics Data System (ADS)

    Gao, Hong-Ying; Wagner, Hendrik; Held, Philipp Alexander; Du, Shixuan; Gao, Hong-Jun; Studer, Armido; Fuchs, Harald

    2015-02-01

    We demonstrate that the Van der Waals interactions in plane are important to control molecular self-assembly structure as well their phase transition. Using precise chemical modification to mediate such in-plane cohesive interactions, we observed the spontaneous formations of 2D order or disorder molecular self-assembly structures, as well their order-disorder phase transitions by annealing. Interestingly, we identified that the side alkyl chains stand up at surfaces and form the `locked' pairs/windmill structures. Moreover, we realized the covalent coupling based on ethynyl functionality before molecular desorption from metal surfaces, by enhancing the in-plane interactions.

  19. Numerical investigation of transitional compressible plane wakes

    NASA Astrophysics Data System (ADS)

    Harris, Paul Jeffrey

    Air flow in the wake region of a two-dimensional (plane) body with a blunt base has been studied using numerical simulations. The objective of this study is (1) to observe the behavior of large dynamic structures in the plane wake at several Mach numbers from low (almost incompressible) up to M = 2.46 and examine their effect on the base pressure, and (2) to address the nature of the instability in the shear layers bounding the wake flow at M = 2.46 and observe the structures that arise from this instability. A code was developed for this study which solves the compressible Navier-Stokes equations in two or three dimensions. This code may be used for either Direct Numerical Simulations (DNS) or Large Eddy Simulations (LES). A spatial model is used, with the computational domain arranged around the trailing edge of a two-dimensional flat plate with a blunt base. Two-dimensional simulations were carried out at Mach numbers of M = 0.25, M = 1.20, and M = 2.46. At all Mach numbers, the flow was found to be unstable with respect to sinuous (antisymmetric) disturbances, with the critical Reynolds number increasing with increasing Mach number. These disturbances grow to a periodic state, and a Karman vortex street is formed. Examination of the supersonic cases revealed that expansion fans in the flow at the corners are the primary cause of the low base pressure, and that disruptions in the expansions raise the base pressure. At M = 2.46 and Reynolds numbers starting at Re = 100, 000, an intermittent shear layer instability was also found, excited by sinuous disturbances. The two instability 2 modes interact to produce a chaotic behavior. Above Re = 200, 000, the shear layer instability appears close to the base without sinuous disturbances, forming rows of vortices in the shear layers. Preliminary three-dimensional simulations were carried out at M = 2.46, examining the variation in the growth rate of three-dimensional disturbances with spanwise wavelength.

  20. Solar Impulse's Solar-Powered Plane

    ScienceCinema

    Moniz, Ernest; Piccard, Bertrand; Reicher, Dan

    2016-07-12

    Solar Impulse lands in Washington, DC at Washington Dulles International Airport as part of its journey across the United States. Secretary Ernest Moniz speaks about how advancements like those at the Department of Energy are leading the way for innovations like the solar-powered plane. Footage of the solar-powered plane courtesy of Solar Impulse.

  1. Aero-space plane figures of merit

    NASA Technical Reports Server (NTRS)

    Hunt, James L.; Martin, John G.

    1992-01-01

    The design environment of the aerospace plane is variable rich, intricately networked and sensitivity intensive. To achieve a viable design necessitates addressing three principal elements: knowledge of the 'figures of merit' and their relationships, the synthesis procedure, and the synergistic integration of advanced technologies across the discipline spectrum. This paper focuses on the 'figures of merit' that create the design of an aerospace plane.

  2. Slipping and Rolling on an Inclined Plane

    ERIC Educational Resources Information Center

    Aghamohammadi, Cina; Aghamohammadi, Amir

    2011-01-01

    In the first part of the paper, using a direct calculation two-dimensional motion of a particle sliding on an inclined plane is investigated for general values of friction coefficient ([mu]). A parametric equation for the trajectory of the particle is also obtained. In the second part of the paper, the motion of a sphere on the inclined plane is…

  3. Solar Impulse's Solar-Powered Plane

    SciTech Connect

    Moniz, Ernest; Piccard, Bertrand; Reicher, Dan

    2013-07-08

    Solar Impulse lands in Washington, DC at Washington Dulles International Airport as part of its journey across the United States. Secretary Ernest Moniz speaks about how advancements like those at the Department of Energy are leading the way for innovations like the solar-powered plane. Footage of the solar-powered plane courtesy of Solar Impulse.

  4. Extracting oblique planes from serial CT sections.

    PubMed

    Rhodes, M L; Glenn, W V; Azaawi, Y M

    1980-10-01

    Although geometric principles describing planes oblique to an orthogonal image data set are well understood, no implementation has been offered for their practical specification, extraction, and display in a clinical environment. Fast image generation and ease of user specification-requisite credentials for successful clinical implementations-are handicapped by the large volume of data to process. Other difficulties further complicate an interactive solution. Once oblique planes are generated, their orientation is often difficult to perceive without visual cues that aid their registration with standard image formats. In addition, Moire patterns introduced by digital aliasing often currupt resultant views. In this paper, techniques are outlined for simplifying oblique plane specification, a methodology is presented for image construction, and an interactive approach is illustrated to register images for such general view planes. Finally, digital aliasing of oblique planes is discussed, and a solution is given for this application.

  5. Study the Z-Plane Strip Capacitance

    SciTech Connect

    Parikh, H.; Swain, S.; /SLAC

    2005-12-15

    The BaBaR detector at the Stanford Linear Accelerator Center is currently undergoing an upgrade to improve its muon and neutral hadron detection system. The Resistive Plate Chambers (RPCs) that had been used till now have deteriorated in performance over the past few years and are being replaced by Limited Streamer Tube (LSTs). Each layer of the system consists of a set of up to 10 streamer tube modules which provide one coordinate ({phi} coordinate) and a single ''Z-plane'' which provides the Z coordinate of the hit. The large area Z-planes (up to 12m{sup 2}) are 1mm thick and contain 96 copper strips that detect the induced charge from avalanches created in the streamer tube wires. All the Z-planes needed for the upgrade have already been constructed, but only a third of the planes were installed last summer. After installing the 24 Z-planes last year, it was learned that 0.7% of the strips were dead when put inside the detector. This was mainly due to the delicate solder joint between the read-out cable and the strip, and since it is difficult to access or replace the Z-planes inside the detector, it is very important to perform various tests to make sure that the Z-planes will be efficient and effective in the long term. We measure the capacitance between the copper strips and the ground plane, and compare it to the theoretical value that we expect. Instead of measuring the capacitance channel by channel, which would be a very tedious job, we developed a more effective method of measuring the capacitance. Since all the Z-planes were built at SLAC, we also built a smaller 46 cm by 30 cm Z-plane with 12 strips just to see how they were constructed and to gain a better understanding about the solder joints.

  6. The invariable plane of the solar system

    NASA Astrophysics Data System (ADS)

    Souami, D.; Souchay, J.

    2012-04-01

    The invariable plane of the solar system is defined as the plane perpendicular to the total angular momentum of the system and passing through its centre of mass. The idea of using the invariable plane as a reference plane in the study of the dynamics of solar system bodies goes back at least to Laplace [3]. The latest study on this plane dates back to Burkhardt [2]. The aim of this work is to determine at best the orientation of the invariable plane with respect to both the ICRS and the equinox-ecliptic of J2000.0, and to evaluate the accuracy of its determination. Such a determination is of fundamental interest in the topic of solar system studies, as suggested by the WGCCRE 2009 [1] for the determination of planet's and satellites' rotational elements. Using the long-term numerical ephemerides DE405, DE406 [6] and INPOP10a[4] over their entire available time span, we compute the total angular momentum of the solar system, as well as the individual contribution of each planet. We then deduce the orientation of the invariable plane for each ephemeris, and establish their relative differences. Preliminary results can be found in [5]. Here we update them with more accurate data, and a more complete analysis of the problem, taking into account the effect of the dwarf planet (1) Ceres as well as two of the biggest asteroids, (4) Vesta and (2) Pallas. Moreover, we give the orbital elements (inclination, longitude of the ascending node) with respect to the invariable plane. As given its accuracy of determination, and its fundamental dynamical meaning, the invariable plane provides a permanent natural reference plane that should be used when studying solar system dynamics, instead of the ecliptic. Thus, we recommend referring to it when working on long-term dynamics.

  7. Exotensioned structural members with energy-absorbing effects

    SciTech Connect

    Brockwell, Michael Ian

    2014-01-07

    Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

  8. Exotensioned structural members with energy-absorbing effects

    SciTech Connect

    Brockwell, Michael Ian

    2015-08-11

    Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

  9. X-ray absorption spectroscopy, EELS, and full-potential augmented plane wave study of the electronic structure of Ti{sub 2}AlC, Ti{sub 2}AlN, Nb{sub 2}AlC, and (Ti{sub 0.5}Nb{sub 0.5}){sub 2}AlC

    SciTech Connect

    Hug, G.; Jaouen, M.; Barsoum, M.W.

    2005-01-01

    The structural parameters of various Haegg phases (H or M{sub n+1}AX{sub n} phases) are studied experimentally by x-ray and electron spectroscopies, x-ray diffraction, and ab initio full potential as well as full mutiple scattering theoretical calculations. Experimentally it was found that the structure of all ternary compounds analyzed herein are relaxed. The values of the lattice parameters and relaxations obtained from ab initio calculations are in excellent agreement with those deduced from the analysis of the experimental data. The bonding scheme has been analyzed and the charge transfer between constituting atoms determined. It is demonstrated that the strength and electrical transport properties in these materials are principally governed by the metallic planes. For the solid solution (Ti{sub 0.5}Nb{sub 0.5}){sub 2}AlC, the most salient result is that the basal planes are corrugated, which could explain the solid solution scattering observed in this H phase.

  10. Overview of Japanese aerospace plane

    NASA Astrophysics Data System (ADS)

    Yamanaka, Tatsuo

    1992-12-01

    The Japanese NAL, NASDA, and ISAS agencies have undertaken development of a Highly Maneuverable Experimental Spaceplane ('HIMES') which will integrate hypersonic technologies currently under development. A development status evaluation of these activities is presented. Attention is given to the configurational features of HIMES, its aerodynamic developmental tests to date, structures and materials considerations, flight control/guidance systems, airbreathing propulsion options, and CFD modeling.

  11. In-Plane Ordering in Diblock Copolymer Brushes.

    NASA Astrophysics Data System (ADS)

    Akgun, Bulent; Ugur, Gokce; Brittain, William J.; Foster, Mark D.; Li, Xuefa; Wang, Jin

    2007-03-01

    Internal and surface structures of polystyrene-b-polyacrylate and polyacrylate-b-polystyrene diblock copolymer brushes have been studied using grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscopy (AFM). Each asymmetric, as-deposited diblock brush that contains a poly(methyl acrylate) (PMA) block shows an in-plane structure with a spacing comparable to the PMA layer thickness. The correlation length of the in-plane ordering is about the nearest neighbor distance and grows with annealing at 180^o C. After a brush is treated with a solvent selective for the bottom block, Bragg rods appear in the GISAXS pattern. The lateral spacing corresponding to the Bragg rods is on the order of the brush total thickness. This lateral correlation is also detected by power spectral density analysis of AFM images of the samples' surfaces. The Bragg rods disappear upon heating to 80^o C.

  12. Quantum dynamics of a plane pendulum

    SciTech Connect

    Leibscher, Monika; Schmidt, Burkhard

    2009-07-15

    A semianalytical approach to the quantum dynamics of a plane pendulum is developed, based on Mathieu functions which appear as stationary wave functions. The time-dependent Schroedinger equation is solved for pendular analogs of coherent and squeezed states of a harmonic oscillator, induced by instantaneous changes of the periodic potential energy function. Coherent pendular states are discussed between the harmonic limit for small displacements and the inverted pendulum limit, while squeezed pendular states are shown to interpolate between vibrational and free rotational motion. In the latter case, full and fractional revivals as well as spatiotemporal structures in the time evolution of the probability densities (quantum carpets) are quantitatively analyzed. Corresponding expressions for the mean orientation are derived in terms of Mathieu functions in time. For periodic double well potentials, different revival schemes, and different quantum carpets are found for the even and odd initial states forming the ground tunneling doublet. Time evolution of the mean alignment allows the separation of states with different parity. Implications for external (rotational) and internal (torsional) motion of molecules induced by intense laser fields are discussed.

  13. A Cool Tool for Deicing Planes

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Nicknamed the "ice zapper," the Electro Expulsive Separation System (EESS) is an aircraft ice removal system that "pulverizes ice and removes layers of ice as thin as frost or as thick as an inch of glaze," according to the principle inventor of the technology. Patented by NASA's Ames Research Center, the EESS consists of layers of conductors encased in materials that are bonded directly to the airframe structure. When ice accumulates on the aircraft, an electric current is sent through the conductors, causing them to pulse. Even though the conductors move less than a twenty-thousandth of an inch in just a millisecond, the movement is sufficient to pulverize the ice. It is this highly accelerated motion that shatters the ice into particles the size of table salt; too small to be harmful to the aircraft. When compared with other systems in use, such as thermal deicers and pneumatic boots, the ice zapper does very well. Thermal deicers are fairly common, although they use an enormous amount of energy and present the possibility of ice refreezing. Pneumatic boots are not always effective because they require an inflation device that is unable to work until a quarter inch of ice has accumulated. With both systems, the ice that is loosened may still be large enough to cause problems for the plane once dislodged.

  14. Determination of the occlusal plane using a custom-made occlusal plane analyzer: a clinical report.

    PubMed

    Bedia, Sumit V; Dange, Shankar P; Khalikar, Arun N

    2007-11-01

    In fixed prosthodontic procedures, when it has been determined that restoration of all or most of the posterior teeth is necessary, the use of the Broderick occlusal plane analyzer provides an easy and practical method to determine an occlusal plane that will fulfill esthetic and functional occlusion requirements. However, several manufacturers of semiadjustable articulators offer no such occlusal plane analyzers for use with these instruments. This article demonstrates the use of a custom-made Broderick occlusal plane analyzer with a semiadjustable articulator to determine the correct curve of Spee for the occlusal plane.

  15. An assessment of tailoring of lightning protection design requirements for a composite wing structure on a metallic aircraft

    NASA Technical Reports Server (NTRS)

    Harwood, T. L.

    1991-01-01

    The Navy A-6E aircraft is presently being modified with a new wing which uses graphite/epoxy structures and substructures around a titanium load-bearing structure. The ability of composites to conduct electricity is less than that of aluminum. This is cause for concern when the wing may be required to conduct large lightning currents. The manufacturer attempted to solve lightning protection issues by performing a risk assessment based on a statistical approach which allows relaxation of the wing lightning protection design levels over certain locations of the composite wing. A sensitivity study is presented designed to define the total risk of relaxation of the design levels.

  16. The lateral plane delivers higher dose than the frontal plane in biplane cardiac catheterization systems.

    PubMed

    Aldoss, Osamah; Patel, Sonali; Harris, Kyle; Divekar, Abhay

    2015-06-01

    The objective of the study is to compare radiation dose between the frontal and lateral planes in a biplane cardiac catheterization laboratory. Tube angulation progressively increases patient and operator radiation dose in single-plane cardiac catheterization laboratories. This retrospective study captured biplane radiation dose in a pediatric cardiac catheterization laboratory between April 2010 and January 2014. Raw and time-indexed fluoroscopic, cineangiographic and total (fluoroscopic + cineangiographic) air kerma (AK, mGy) and kerma area product (PKA, µGym(2)/Kg) for each plane were compared. Data for 716 patients were analyzed: 408 (56.98 %) were male, the median age was 4.86 years, and the median weight was 17.35 kg. Although median beam-on time (minutes) was 4.2 times greater in the frontal plane, there was no difference in raw median total PKA between the two planes. However, when indexed to beam-on time, the lateral plane had a higher median-indexed fluoroscopic (0.75 vs. 1.70), cineangiographic (16.03 vs. 24.92), and total (1.43 vs. 5.15) PKA (p < 0.0001). The median time-indexed total PKA in the lateral plane is 3.6 times the frontal plane. This is the first report showing that the lateral plane delivers a higher dose than the frontal plane per unit time. Operators should consciously reduce the lateral plane beam-on time and incorporate this practice in radiation reduction protocols.

  17. Advanced approaches to focal plane integration

    NASA Astrophysics Data System (ADS)

    Nelson, R. D.; Smith, E. C., Jr.

    1980-01-01

    Both visible and infrared focal plane assemblies have common architectural driving parameters which guide their design approaches. The key drivers for advanced focal plane assemblies (FPA) are: the detector type and performance required; the number of detector chips; the packaging density; and the geometry. The impact of these drivers is seen to determine the engineering compromises necessary to establish FPA design approach. Several new designs are discussed which show a range of applications from single detector assemblies to monolithic detector chips with on-chip signal processing. The main objective of many advanced designs is to integrate the focal plane components in order to reduce power and reduce the number of interconnections.

  18. Streptococcus anginosus infections: crossing tissue planes.

    PubMed

    Sunwoo, Bernie Y; Miller, Wallace T

    2014-10-01

    Streptococcus anginosus has long been recognized to cause invasive pyogenic infections. This holds true for thoracic infections where S. anginosus has a propensity for abscess and empyema formation. Early diagnosis is important given the significant morbidity and mortality associated with thoracic S. anginosus infections. Yet, distinguishing thoracic S. anginosus clinically is difficult. We present three cases of thoracic S. anginosus that demonstrated radiographic extension across tissue planes, including the interlobar fissure, diaphragm, and chest wall. Few infectious etiologies are known to cross tissue planes. Accordingly, we propose S. anginosus be considered among the differential diagnosis of potential infectious etiologies causing radiographic extension across tissue planes.

  19. Far-Infrared Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Betz, A. L.; Boreiko, R. T.; Sivananthan, S.; Zhou, Y. D.

    The development of focal plane arrays has dramatically increased the sensitivity and efficiency of optical and infrared telescopes. The versatility of HgCdTe alloy technology has been demonstrated by detector arrays with cutoff wavelengths tailored between λc = 1-10 μm. Although the cutoff wavelength can theoretically be extended to infinity (zero gap) by increasing the HgTe mole fraction, the required accuracy of the alloy composition is difficult to achieve with conventional liquid-phase-epitaxy (LPE). The more recent technique of molecular-beam-epitaxy (MBE), on the other hand, provides the necessary precision, and detector arrays appear feasible out to λc = 100 μm. Although the alloy approach should work, an alternate device structure may prove superior. Rather than alloying HgTe and CdTe, one can deposit alternating layers of the two materials in a composite structure called a superlattice (SL). Because layer thickness (rather than alloy composition) determines the cutoff wavelength in a SL, this approach should prove easier for fabricating an Eg = 0.01 eV semiconductor. Photodiodes made from SL material should also have lower tunneling currents, which are the dominant source of noise in low gap devices. This talk will describe a NASA-funded project to develop HgCdTe detectors for FIR wavelengths. Work is now in progress on the fabrication of discrete detectors, with emphasis on the superlattice approach. Within 3 years we hope to have a 32 x 32 element array for λ = 50-60 μm. The ultimate goal is a 128 x 128 element array for λ = 50-100 μm that could be used on a SOFIA instrument.

  20. Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Kohlhoff, Harald; Hofmann, Detlef; Basedau, Frank; Habel, Wolfgang R.; Baeßler, Matthias; Niederleithinger, Ernst; Georgi, Steven; Herten, Markus

    2013-05-01

    Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load tests and pile integrity tests.

  1. On carrier spillover in c- and m-plane InGaN light emitting diodes

    NASA Astrophysics Data System (ADS)

    Lee, J.; Li, X.; Ni, X.; Özgür, Ü.; Morkoç, H.; Paskova, T.; Mulholland, G.; Evans, K. R.

    2009-11-01

    The internal quantum efficiency (IQE) and relative external quantum efficiency (EQE) in InGaN light-emitting diodes (LEDs) emitting at 400 nm with and without electron blocking layers (EBLs) on c-plane GaN and m-plane GaN were investigated in order to shed some light on any effect of polarization charge induced field on efficiency killer carrier spillover. Without an EBL the EQE values suffered considerably (by 80%) for both orientations, which is clearly attributable to carrier spillover. Substantial carrier spillover in both polarities, therefore, suggests that the polarization charge is not the major factor in efficiency degradation observed, particularly at high injection levels. Furthermore, the m-plane variety with EBL did not show any discernable efficiency degradation up to a maximum current density of 2250 A cm-2 employed while that on c-plane showed a reduction by ˜40%. In addition, IQE of m-plane LED structure determined from excitation power dependent photoluminescence was ˜80% compared to 50% in c-plane LEDs under resonant and moderate excitation condition. This too is indicative of the superiority of m-plane LED structures, most probably due to relatively larger optical matrix elements for m-plane orientation.

  2. Plane Strain Testing with Passive Restraint

    NASA Astrophysics Data System (ADS)

    Makhnenko, Roman; Labuz, Joseph

    2014-11-01

    A plane strain condition for testing rock is developed through passive restraint in the form of a thick-walled cylinder. The so-called biaxial frame generates the intermediate principal stress that imposes a triaxial state of stress on a prismatic specimen. Major and minor principal stresses and corresponding strains are accurately measured, providing data to calculate the elastic (Young's modulus and Poisson's ratio), inelastic (dilatancy angle), and strength (friction angle and cohesion) parameters of the rock. Results of experiments conducted on Indiana limestone in plane strain compression are compared with the results of axisymmetric compression and extension. With proper system calibration, Young's modulus and Poisson's ratio are consistent among the tests. The plane strain apparatus enforces in-plane deformation with the three principal stresses at failure being different, and it allows one to determine the Paul-Mohr-Coulomb failure surface, which includes an intermediate stress effect.

  3. Attitude analysis in Flatland: The plane truth

    NASA Technical Reports Server (NTRS)

    Shuster, Malcolm D.

    1993-01-01

    Many results in attitude analysis are still meaningful when the attitude is restricted to rotations about a single axis. Such a picture corresponds to attitude analysis in the Euclidean plane. The present report formalizes the representation of attitude in the plane and applies it to some well-known problems. In particular, we study the connection of the 'additive' and 'multiplicative' formulations of the differential corrector for the quaternion in its two-dimensional setting.

  4. Stability and Load Bearing Capacity of a Bars with Built up Cross Section and Elastic Supports / Badania Stateczności I Nosności Prętów Złożonych Z Podporami Sprężystymi

    NASA Astrophysics Data System (ADS)

    Krajewski, Marcin

    2015-03-01

    The present paper is devoted to the numerical analysis and experimental tests of compressed bars with built-up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static analysis results, with material and geometrical nonlinearity, are presented for the bar with built-up cross section which was used as the top chord of the truss made in reality. Diagonals and verticals which are supports for the top chord between marginal joints were replaced by the elastic supports. The threshold stiffness (minimum stiffness) for the intermediate elastic supports which ensures maximum buckling load was appointed for the beam and shell model of the structure. The magnitude of limit load depended on length of the battens was calculated for models with initial geometric imperfections. The experimental tests results for the axially compressed bars with builtup cross section and elastic support are presented. Niniejsza praca poświecona jest analizom numerycznym i badaniom doświadczalnym ściskanych prętów złożonych, które są często stosowane, jako pasy górne kratownic dachowych. Istotny wpływ na nośność tego typu elementów, przy założeniu wyboczenia z płaszczyzny układu, ma odpowiedni dobór przewiązek zapewniający współpracę poszczególnych gałęzi. W pracy przedstawiono rezultaty liniowych analiz stateczności oraz fizycznie i geometrycznie nieliniowych analiz statycznych dla pręta złożonego, z którego zbudowany jest pas górny kratownicy wykonanej w rzeczywistości. Słupki i krzyżulce podpierające pas między węzłami skrajnymi zastąpiono podporami sprężystymi. Wyznaczono graniczną (minimalna) sztywność sprężystych podpór pośrednich zapewniającą maksymalną wartość obci

  5. The formation of Local Group planes of galaxies

    NASA Astrophysics Data System (ADS)

    Shaya, Ed J.; Tully, R. Brent

    2013-12-01

    The confinement of most satellite galaxies in the Local Group to thin planes presents a challenge to the theory of hierarchical galaxy clustering. The Pan-Andromeda Archaeological Survey (PAndAS) collaboration has identified a particularly thin configuration with kinematic coherence among companions of M31 and there have been long-standing claims that the dwarf companions to the Milky Way lie in a plane roughly orthogonal to the disc of our galaxy. This discussion investigates the possible origins of four Local Group planes: the plane similar, but not identical to that identified by the PAndAS collaboration, an adjacent slightly tilted plane and two planes in the vicinity of the Milky Way: one with very nearby galaxies and the other with more distant ones. Plausible orbits are found by using a combination of Numerical Action methods and a backward in time integration procedure. This investigation assumes that the companion galaxies formed at an early time in accordance with the standard cosmological model. For M31, M33, IC10 and Leo I, solutions are found that are consistent with measurements of their proper motions. For galaxies in planes, there must be commonalities in their proper motions, and this constraint greatly limits the number of physically plausible solutions. Key to the formation of the planar structures has been the evacuation of the Local Void and consequent build-up of the Local Sheet, a wall of this void. Most of the M31 companion galaxies were born in early-forming filamentary or sheet-like substrata that chased M31 out of the void. M31 is a moving target because of its attraction towards the Milky Way, and the result has been alignments stretched towards our galaxy. In the case of the configuration around the Milky Way, it appears that our galaxy was in a three-way competition for companions with M31 and Centaurus A. Only those within a modest band fell our way. The Milky Way's attraction towards the Virgo Cluster resulted in alignment along the

  6. Technology challenges for the National Aero-Space Plane

    NASA Technical Reports Server (NTRS)

    Piland, William M.

    1987-01-01

    The National Aerospace Plane (NASP) will require an exceptionally high degree of integration between propulsion and aerodynamic configuration, in order to achieve the requisite specific impulse and low structural weight. This is to be achieved through the use of forebody shock compression and afterbody exhaust expansion. Attention is presently given to the materials and structural concepts required for the realization of these NASP airframe functions, in view of the exceptionally high aerothermodynamic loads that will be experienced at hypersonic speeds. Active cooling will have to be used in certain critical airframe and propulsion components. CFD characterizations of these processes must be carefully developed and fully validated.

  7. Conceptual design on H-2 Orbiting Plane (HOPE)

    NASA Astrophysics Data System (ADS)

    1993-03-01

    An overview of the results of the studies on technical problems concerning the following subjects related to the HOPE (H-2 Orbiting Plane) is presented: (1) technical problems on system design, aerodynamic design, thermal structure design, thermal control system design, and guidance and control system design; (2) studies on designs for the system, aerodynamic characteristics, thermal structure, actuator system, thermal control system, payload support system, and guidance and control system; (3) studies on operational concepts and overall operation system; and (4) study of development program.

  8. Direct numerical simulation of turbulent plane Couette flow

    NASA Technical Reports Server (NTRS)

    Lee, Moon Joo

    1991-01-01

    Turbulent plane Couette flow was numerically simulated at a Reynolds number (U(sub w)h/nu) of 6000, where U(sub w) is the relative wall speed and h is half the channel-height. Unlike in Poiseuille flow, where the mean shear rate changes its sign at the centerline, the sign of mean shear rate in plane Couette flow remains the same across the whole channel. This difference is expected to yield several differences between the two flows, especially in the core region. The most significant and dramatic difference observed was the existence of large-scale structures in the core region of the plane Couette flow. The large eddies are extremely long in the flow direction and fill the entire channel (i.e., their vertical extent is 2h). The large-scale structures have the largest contribution from the wavenumber (k(sub x)h,k(sub z)h) = (0, plus or minus 1.5), corresponding to a wavelength lambda(sub z)/h is approximately equal to 4. The secondary motion associated with the k(sub x)h = 0 mode consists of the large-scale vortices. The large eddies contribute about 30 percent of turbulent kinetic energy.

  9. The in-plane shear properties of pultruded materials

    NASA Astrophysics Data System (ADS)

    Cho, Baik-Soon

    1998-12-01

    This thesis presents the details for a new in-plane shear test method applicable to pultruded materials reinforced with continuous strand mat (CSM) and rovings. The loading system and the size of the specimen are different from those currently used in the ASTM D-5379 specification in order to reduce the effect of the inherent heterogeneity of the pultruded materials. Then, the performance of the ASTM D-5379 V-notched beam test fixture and that of the newly developed test fixture at the Georgia Institute of Technology will be discussed. The thesis also presents various predicted techniques for estimating the in-plane shear modulus of pultruded materials from the properties of the constituents. Finally, a third-order polynomial shear stress---shear strain (tau - gamma) equation is proposed for more accurate structural analysis of pultruded materials reinforced with rovings and continuous strand mats.

  10. Biomechanical differences between incline and plane hopping.

    PubMed

    Kannas, Theodoros M; Kellis, Eleftherios; Amiridis, Ioannis G

    2011-12-01

    Kannas, TM, Kellis, E, and Amiridis, IG. Biomechanical differences between incline and plane hopping. J Strength Cond Res 25(12): 3334-3341, 2011-The need for the generation of higher joint power output during performance of dynamic activities led us to investigate the force-length relationship of the plantar flexors during consecutive stretch-shortening cycles of hopping. The hypothesis of this study was that hopping (consecutive jumps with the knee as straight as possible) on an inclined (15°) surface might lead to a better jumping performance compared with hopping on a plane surface (0°). Twelve active men performed 3 sets of 10 consecutive hops on both an incline and plane surface. Ground reaction forces; ankle and knee joint kinematics; electromyographic (EMG) activity from the medial gastrocnemius (MG), soleus (Sol) and tibialis anterior (TA); and architectural data from the MG were recorded. The results showed that participants jumped significantly higher (p < 0.05) when hopping on an inclined surface (30.32 ± 8.18 cm) compared with hopping on a plane surface (27.52 ± 4.97 cm). No differences in temporal characteristics between the 2 types of jumps were observed. Incline hopping induced significantly greater ankle dorsiflexion and knee extension at takeoff compared with plane hopping (p < 0.05). The fascicle length of the MG was greater at initial contact with the ground during incline hopping (p < 0.05). Moreover, the EMG activities of Sol and TA during the propulsion phase were significantly higher during incline compared with that during plane hopping (p < 0.05). It does not seem unreasonable to suggest that, if the aim of hopping plyometrics is to improve plantar flexor explosivity, incline hopping might be a more effective exercise than hopping on a plane surface.

  11. INTERIOR OF SECOND FLOOR BRIDGE BETWEEN PLANING MILL AND CAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR OF SECOND FLOOR BRIDGE BETWEEN PLANING MILL AND CAR MACHINE SHOP, LOOKING SOUTH TOWARD PLANING MILL. - Southern Pacific, Sacramento Shops, Planing Mill, 111 I Street, Sacramento, Sacramento County, CA

  12. Rotating the plane of imposed vibration can rotate the plane of flagellar beating in sea-urchin sperm without twisting the axoneme.

    PubMed

    Shingyoji, C; Katada, J; Takahashi, K; Gibbons, I R

    1991-02-01

    When the head of a sea-urchin sperm is held in the tip of a micropipette and vibrated laterally, the flagellum beats in phase with the imposed vibration. Rotation of the plane of pipette vibration around the head axis induces a corresponding rotation of the plane of beating, in both live and reactivated sperm. Detailed analysis of the waveforms occurring at different stages of this rotation shows that the characteristic asymmetry of the flagellar bending waves rotates along with the plane of beat. The positions of small polystyrene beads attached as markers on the axonemes of demembranated sperm flagella appear unaffected by the rotation of the beat plane and asymmetry. The imposed rotation of the waveform is thus the result of a rotation of the coordinated pattern of sliding among the doublet tubules of the axoneme, and is not accompanied by a twisting of the whole axonemal structure. These data indicate that neither the plane of flagellar beat nor the direction of beat asymmetry is tightly dependent upon a structural or chemical specialization of particular members of the nine outer doublet microtubules, but that both are the result of some regulatory structure that can be forced to rotate relative to the outer structure of the axoneme.

  13. Assembly of Spherical Colloids by Short-range Out-of-plane Attraction and Long-range In-plane Repulsion

    NASA Astrophysics Data System (ADS)

    Ma, Fuduo; Wu, David T.; Wu, Ning

    2013-03-01

    The electric-field assembly of spherical colloids with isotropic surface properties has been studied in both two- and three- dimensions. Structures, such as FCC, HCP, and BCT crystals were observed. Recently, we have found surprisingly new types of structures within a previously unexplored experimental regime: low frequency regime (100 Hz to 10 kHz) and low salt concentrations (below 10-4 M). At low particle concentrations, a family of well-defined clusters, ranging from 3 to 10 was observed. Statistical analysis of the population distribution reveled non-trivial peaks for trimers, tetramers, hexamers, and nonamers. We attribute these new types of non-planar structures to a short-range out-of-plane (the plane refers to the substrate) attraction and a long-range in-plane repulsion. For example, the double layer and in-plane dipolar repulsion could make bottom particles in the clusters separate from each other. While the out-of-plane dipolar attraction and particle-substrate attraction could be responsible for the formation of the clusters, i.e., the top central sphere is associated with the bottom spheres. Phase diagrams from experiments and simulation will be compared. These clusters could be used as building blocks for making photonic crystal, filtration, and plasmonic structures.

  14. A Viewpoint on the Quantity "Plane Angle"

    NASA Astrophysics Data System (ADS)

    Eder, W. E.

    1982-01-01

    Properties of the quantity "plane angle" are explored under the hypothesis that it is a dimensional quantity. The exploration proceeds especially with respect to the physical concept, its mathematical treatment, vector concepts, measurement theory, units of related quantities, engineering pragmatism, and SI. An attempt is made to bring these different relations into a rational, logical and consistent framework, and thus to justify the hypothesis. Various types of vectorial quantities are recognized, and their properties described with an outline of the necessary algebraic manipulations. The concept of plane angle is amplified, and its interdependence with the circular arc is explored. The resulting units of plane angle form a class of similar scales of measurement. Consequences of the confirmed hypothesis are developed for mathematical expressions involving trigonometric functions, rotational volumes and areas, mathematical limits, differentiation and series expansion. Consequences for mechanical rotational quantities are developed, with proposals for revisions to a number of expressions for derived units within SI. A revised definition for the quantity "plane angle" is stated to take account of the developed insights. There is a clear need to reconsider the status of plane angle and some other quantities within the international framework of SI.

  15. Focal Plane Metrology for the LSST Camera

    SciTech Connect

    A Rasmussen, Andrew P.; Hale, Layton; Kim, Peter; Lee, Eric; Perl, Martin; Schindler, Rafe; Takacs, Peter; Thurston, Timothy; /SLAC

    2007-01-10

    Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5{sup o}) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 {micro}m P-V) over the entire field of view (640 mm diameter) at the operating temperature (T {approx} -100 C) and over the operational elevation angle range. We briefly describe the hierarchical design approach for the LSST Camera focal plane and the baseline design for assembling the flat focal plane at room temperature. Preliminary results of gravity load and thermal distortion calculations are provided, and early metrological verification of candidate materials under cold thermal conditions are presented. A detailed, generalized method for stitching together sparse metrology data originating from differential, non-contact metrological data acquisition spanning multiple (non-continuous) sensor surfaces making up the focal plane, is described and demonstrated. Finally, we describe some in situ alignment verification alternatives, some of which may be integrated into the camera's focal plane.

  16. GLAMER - II. Multiple-plane gravitational lensing

    NASA Astrophysics Data System (ADS)

    Petkova, Margarita; Metcalf, R. Benton; Giocoli, Carlo

    2014-12-01

    We present an extension to multiple planes of the gravitational lensing code GLAMER. The method entails projecting the mass in the observed light-cone on to a discrete number of lens planes and inverse ray-shooting from the image to the source plane. The mass on each plane can be represented as haloes, simulation particles, a projected mass map extracted form a numerical simulation or any combination of these. The image finding is done in a source-oriented fashion, where only regions of interest are iteratively refined on an initially coarse image plane grid. The calculations are performed in parallel on shared memory machines. The code is able to handle different types of analytic haloes (NFW, NSIE, power law, etc.), haloes extracted from numerical simulations and clusters constructed from semi-analytic models (MOKA). Likewise, there are several different options for modelling the source(s) which can be distributed throughout the light-cone. The distribution of matter in the light-cone can be either taken from a pre-existing N-body numerical simulations, from halo catalogues, or are generated from an analytic mass function. We present several tests of the code and demonstrate some of its applications such as generating mock images of galaxy and galaxy cluster lenses.

  17. Wind/seismic comparisons for upgrading existing structures

    SciTech Connect

    Giller, R.A. )

    1989-10-01

    This paper depicts the analysis procedures and methods used to evaluate three existing building structures for extreme wind loads. The three structures involved in this evaluation are located at the US Department of Energy's Hanford Site near Richland, Washington. This site is characterized by open flat grassland with few surrounding obstructions and has extreme winds in lieu of tornados as a design basis accident condition. This group of buildings represents a variety of construction types, including a concrete stack, a concrete load-bearing wall structure, and a rigid steel-frame building. The three structures included in this group have recently been evaluated for response to the design basis earthquake that included non-linear time history effects. The resulting loads and stresses from the wind analyses were compared to the loads and stresses resulting from seismic analyses. This approach eliminated the need to prepare additional capacity calculations that were already contained in the seismic evaluations. 4 refs., 5 figs., 5 tabs.

  18. Electromagnetic diffraction by plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Bocker, R. P.; Marathay, A. S.

    1972-01-01

    A plane wave theory was developed to study electromagnetic diffraction by plane reflection diffraction gratings of infinite extent. A computer program was written to calculate the energy distribution in the various orders of diffraction for the cases when the electric or magnetic field vectors are parallel to the grating grooves. Within the region of validity of this theory, results were in excellent agreement with those in the literature. Energy conservation checks were also made to determine the region of validity of the plane wave theory. The computer program was flexible enough to analyze any grating profile that could be described by a single value function f(x). Within the region of validity the program could be used with confidence. The computer program was used to investigate the polarization and blaze properties of the diffraction grating.

  19. Solid-state curved focal plane arrays

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh (Inventor); Hoenk, Michael (Inventor); Jones, Todd (Inventor)

    2010-01-01

    The present invention relates to curved focal plane arrays. More specifically, the present invention relates to a system and method for making solid-state curved focal plane arrays from standard and high-purity devices that may be matched to a given optical system. There are two ways to make a curved focal plane arrays starting with the fully fabricated device. One way, is to thin the device and conform it to a curvature. A second way, is to back-illuminate a thick device without making a thinned membrane. The thick device is a special class of devices; for example devices fabricated with high purity silicon. One surface of the device (the non VLSI fabricated surface, also referred to as the back surface) can be polished to form a curved surface.

  20. Optimal plane change by low aerodynamic forces

    NASA Technical Reports Server (NTRS)

    Vinh, Nguyen X.; Ma, Der-Ming

    1990-01-01

    This paper presents the exact dimensionless equations of motion and the necessary conditions for the computation of the optimal trajectories of a hypervelocity vehicle flying through a nonrotating spherical planetary atmosphere. It is shown that there are two types of maneuvers with nearly identical plane change. In the hard maneuver, the vehicle is pulled down to low altitude for aerodyamic plane change before exit at the prescribed final speed. In the slow maneuver which is described in detail in this paper, the vehicle remains in orbital flight with a small incremental plane change during each passage through the perigee. This maneuver requires several revolutions, and the technique for computation is similar to that in the problem of contraction of orbit.

  1. Turbulent boundary layers over nonstationary plane boundaries

    NASA Technical Reports Server (NTRS)

    Roper, A. T.

    1976-01-01

    Methods of predicting integral parameters and skin-friction coefficients of turbulent boundary layers developing over moving-ground-planes are evaluated using test information from three different wind tunnel facilities at the NASA Langley Research Center. These data include test information from the VSTOL tunnel which is presented for the first time. The three methods evaluated were: (1) relative integral parameter method, (2) relative power law method, and (3) modified law of the wall method. Methods (1) and (2) can be used to predict moving-ground-plane shape factors with an expected accuracy of + or - 10%. They may also be used to predict moving-ground-plane displacement and momentum thicknesses with lower expected accuracy. This decrease in accuracy can be traced to the failure of approximations upon which these methods are based to prove universal when compared with VSTOL tunnel test results.

  2. A miniature robotic plane meteorological sounding system

    NASA Astrophysics Data System (ADS)

    Ma, Shuqing; Chen, Hongbin; Wang, Gai; Pan, Yi; Li, Qiang

    2004-12-01

    This article presents a miniature robotic plane meteorological sounding system (RPMSS), which consists of three major subsystems: a miniature robotic plane, an air-borne meteorological sounding and flight control system, and a ground-based system. Take-off and landing of the miniature aircraft are guided by radio control, and the flight of the robotic plane along a pre-designed trajectory is automatically piloted by an onboard navigation system. The observed meteorological data as well as all flight information are sent back in real time to the ground, then displayed and recorded by the ground-based computer. The ground-based subsystem can also transmit instructions to the air-borne control subsystem. Good system performance has been demonstrated by more than 300 hours of flight for atmospheric sounding.

  3. Are rotating planes of satellite galaxies ubiquitous?

    NASA Astrophysics Data System (ADS)

    Phillips, John I.; Cooper, Michael C.; Bullock, James S.; Boylan-Kolchin, Michael

    2015-11-01

    We compare the dynamics of satellite galaxies in the Sloan Digital Sky Survey to simple models in order to test the hypothesis that a large fraction of satellites corotate in coherent planes. We confirm the previously reported excess of corotating satellite pairs located near diametric opposition with respect to their host, but show that this signal is unlikely to be due to rotating discs (or planes) of satellites. In particular, no overabundance of corotating satellites pairs is observed within ˜20°-50° of direct opposition, as would be expected for planar distributions inclined relative to the line of sight. Instead, the excess corotation for satellite pairs within ˜10° of opposition is consistent with random noise associated with undersampling of an underlying isotropic velocity distribution. Based upon the observed dynamics of the luminous satellite population, we conclude that at most 10 per cent of isolated hosts harbour corotating satellite planes (as traced by bright satellites).

  4. NASA R and T aerospace plane vehicles: Progress and plans

    NASA Technical Reports Server (NTRS)

    Dixon, S. C.

    1985-01-01

    Progress made in key technologies such as materials, structures, aerothermodynamics, hypersonic aerodynamics, and hypersonic airbreathing propulsion are reported. Advances were made in more generic, areas such as active controls, flight computer hardware and software, and interdisciplinary analytical design methodology. These technology advances coupled with the development of and experiences with the Space Shuttle make feasible aerospace plane-type vehicles that meet the more demanding requirements of various DOD missions and/or an all-weather Shuttle II with reduced launch costs. Technology needs and high payoff technologies, and the technology advancements in propulsion, control-configured-vehicles, aerodynamics, aerothermodynamics, aerothermal loads, and materials and structures were studied. The highest payoff technologies of materials and structures including thermal-structural analysis and high temperature test techniques are emphasized. The high priority technology of propulsion, and plans, of what remains to be done rather than firm program commitments, are briefly discussed.

  5. Structural and functional diversity of desmosomes.

    PubMed

    Harmon, Robert M; Green, Kathleen J

    2013-12-01

    Desmosomes anchor intermediate filaments at sites of cell contact established by the interaction of cadherins extending from opposing cells. The incorporation of cadherins, catenin adaptors, and cytoskeletal elements resembles the closely related adherens junction. However, the recruitment of intermediate filaments distinguishes desmosomes and imparts a unique function. By linking the load-bearing intermediate filaments of neighboring cells, desmosomes create mechanically contiguous cell sheets and, in so doing, confer structural integrity to the tissues they populate. This trait and a well-established role in human disease have long captured the attention of cell biologists, as evidenced by a publication record dating back to the mid-1860s. Likewise, emerging data implicating the desmosome in signaling events pertinent to organismal development, carcinogenesis, and genetic disorders will secure a prominent role for desmosomes in future biological and biomedical investigations.

  6. Note: A novel integrated microforce measurement system for plane-plane contact research

    NASA Astrophysics Data System (ADS)

    Dong, W.; Rostoucher, D.; Gauthier, M.

    2010-11-01

    The evaluation of plane-plane contact force has become a big issue in micro-/nano research, for example in microassembly. However with the lack of effective experimental equipments, the research on plane-plane contact has been limited to theoretical formulations or virtual simulation. In this paper, a microforce sensor and precision parallel robot integrated system is proposed for the microforce measurement of plane-plane contact. In the proposed system, the two objects are fixed on the parallel robot end-platform and the microforce sensor probe tip, respectively, and the high precision robot system is employed to provide six degree-of-freedom motions between both objects. So it is convenient for the microforce measurement between the planar objects with different orientations. As a significant application, the proposed system is utilized for measurements of pull-off force between planar objects, in which the validation of the system is demonstrated in practice. The proposed microforce measurement system is generic, which can be extended to a variety of microforce measurements in plane-plane contact.

  7. Current-induced in-plane superconducting transition in intrinsic Josephson junctions

    NASA Astrophysics Data System (ADS)

    You, L. X.; Yurgens, A.; Winkler, D.; Torstensson, M.; Kajiki, K.; Tanaka, I.

    2006-05-01

    In stacks of intrinsic Josephson junctions (IJJs) with lateral sizes of several microns, the current is non-uniform in many cases. In certain geometries a significant part of the current flows along the superconducting planes and can reach the critical value. The current-driven superconductivity breakdown within a single Cu2O4 plane can be seen as an extra branch structure of the c-axis current-voltage characteristics. This allows us to deduce the sheet critical current of a single Cu2O4 plane in different measurement configurations. The conditions for the observation of such a current-induced transition in different IJJ geometries are discussed.

  8. Out-of-Plane Coordinated Porphyrin Nanotubes with Enhanced Singlet Oxygen Generation Efficiency

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Wang, Yao; Xu, Yanshuang; Yan, Yun; Huang, Jianbin

    2016-08-01

    A supramolecular porphyrin nanotube displaying J-aggregation feature was constructed by out-of-plane coordinated bismuth-porphyrin. Significantly, compared to traditional J-aggregated porphyrin suffering from fluorescence and singlet oxygen quenching, the nanotube exhibits excellent bio-imaging ability and enhanced production efficiency of singlet oxygen. The out-of-plane structure of bismuth to porphyrin makes the aggregation an appropriate material for theranostics. Furthermore, it is also a potential radio-therapeutic drug owing to the presence of radio-active bismuth. Thus, the self-assembly of out-of-plane coordinated porphyrin can be a facile approach toward effective therapy of tumors and other diseases.

  9. Parameterization of the three-dimensional room transfer function in horizontal plane.

    PubMed

    Bu, Bing; Abhayapala, Thushara D; Bao, Chang-chun; Zhang, Wen

    2015-09-01

    This letter proposes an efficient parameterization of the three-dimensional room transfer function (RTF) which is robust for the position variations of source and receiver in respective horizontal planes. Based on azimuth harmonic analysis, the proposed method exploits the underlying properties of the associated Legendre functions to remove a portion of the spherical harmonic coefficients of RTF which have no contribution in the horizontal plane. This reduction leads to a flexible measuring-point structure consisting of practical concentric circular arrays to extract horizontal plane RTF coefficients. The accuracy of the above parameterization is verified through numerical simulations. PMID:26428827

  10. Plane-wave analysis of solar acoustic-gravity waves: A (slightly) new approach

    NASA Technical Reports Server (NTRS)

    Bogart, Richard S.; Sa, L. A. D.; Duvall, Thomas L., Jr.; Haber, Deborah A.; Toomre, Juri; Hill, Frank

    1995-01-01

    The plane-wave decomposition of the acoustic-gravity wave effects observed in the photosphere provides a computationally efficient technique that probes the structure of the upper convective zone and boundary. In this region, the flat sun approximation is considered as being reasonably accurate. A technique to be used for the systematic plane-wave analysis of Michelson Doppler imager data, as part of the solar oscillations investigation, is described. Estimates of sensitivity are presented, and the effects of using different planar mappings are discussed. The technique is compared with previous approaches to the three dimensional plane-wave problem.

  11. Hybrid Extrinsic Silicon Focal Plane Architecture

    NASA Astrophysics Data System (ADS)

    Pommerrenig, D. H.; Meinhardt, T.; Lowe, J.

    1981-02-01

    Large-area focal planes require mechanical assembly techniques which must be compatible with optical alignment, minimum deadspace, and cryogenic requirements in order to achieve optimum performance. Hybrid extrinsic silicon has been found particularly suitable for such an application. It will be shown that by choosing a large-area extrinsic silicon detector array which is hybrid-mated to a multiplicity of multiplexers a very cost-effective and high-density focal plane module can be assembled. Other advantages of this approach are inherent optical alignment and excellent performance.

  12. Trajectory optimization for the national aerospace plane

    NASA Technical Reports Server (NTRS)

    Lu, Ping

    1993-01-01

    During the past six months the research objectives outlined in the last semi-annual report were accomplished. Specifically, these are: three-dimensional (3-D) fuel-optimal ascent trajectory of the aerospace plane and the effects of thrust vectoring control (TVC) on the fuel consumption and trajectory shaping were investigated; the maximum abort landing area (footprint) was studied; preliminary assessment of simultaneous design of the ascent trajectory and the vehicle configuration for the aerospace plane was also conducted. The work accomplished in the reporting period is summarized.

  13. Horizons and plane waves: A review

    SciTech Connect

    Hubeny, Veronika E.; Rangamani, Mukund

    2003-11-06

    We review the attempts to construct black hole/string solutions in asymptotically plane wave spacetimes. First, we demonstrate that geometries admitting a covariantly constant null Killing vector cannot admit event horizons, which implies that pp-waves can't describe black holes. However, relaxing the symmetry requirements allows us to generate solutions which do possess regular event horizons while retaining the requisite asymptotic properties. In particular, we present two solution generating techniques and use them to construct asymptotically plane wave black string/brane geometries.

  14. Computer Model Of Focal Plane Array

    NASA Astrophysics Data System (ADS)

    Thvedt, Tom A.; Willoughby, Charles T.; Salcido, Michael M.; Dereniak, Eustace L.

    1987-11-01

    This paper presents a computer program for simulation of an infrared focal plane array. Standard equations are used to support a menu driven program developed for an IBM personal computer. The terms and equations for each section are presented and samples of actual screen displays of a currently available device are also included. The program is intended to provide the user with a better capability to understand and to study the tradeoffs of fabrication parameters versus the focal plane array performance (i.e. CTE, both spatial and temporal dynamic range, MTF, and noise) used for an optical sensor system analysis. Only surface channel devices are considered in the simulation.

  15. Application of morphological bit planes in retinal blood vessel extraction.

    PubMed

    Fraz, M M; Basit, A; Barman, S A

    2013-04-01

    The appearance of the retinal blood vessels is an important diagnostic indicator of various clinical disorders of the eye and the body. Retinal blood vessels have been shown to provide evidence in terms of change in diameter, branching angles, or tortuosity, as a result of ophthalmic disease. This paper reports the development for an automated method for segmentation of blood vessels in retinal images. A unique combination of methods for retinal blood vessel skeleton detection and multidirectional morphological bit plane slicing is presented to extract the blood vessels from the color retinal images. The skeleton of main vessels is extracted by the application of directional differential operators and then evaluation of combination of derivative signs and average derivative values. Mathematical morphology has been materialized as a proficient technique for quantifying the retinal vasculature in ocular fundus images. A multidirectional top-hat operator with rotating structuring elements is used to emphasize the vessels in a particular direction, and information is extracted using bit plane slicing. An iterative region growing method is applied to integrate the main skeleton and the images resulting from bit plane slicing of vessel direction-dependent morphological filters. The approach is tested on two publicly available databases DRIVE and STARE. Average accuracy achieved by the proposed method is 0.9423 for both the databases with significant values of sensitivity and specificity also; the algorithm outperforms the second human observer in terms of precision of segmented vessel tree.

  16. Pressure Stagnation Line on a Planing Hull in Calm Water

    NASA Astrophysics Data System (ADS)

    Ikeda, Christine; Judge, Carolyn

    2014-11-01

    High-speed planing boats are subjected to repeat impacts due to slamming, which can cause structural damage and discomfort or injury to passengers. An experimental study aimed at understanding and predicting the physics of a planing craft re-entering the water after becoming partially airborne was conducted. A subset of this experiment includes calm water analysis to gain an understanding of the pressure stagnation line and its correlation with the wetted surface on the planning craft in calm water conditions. A planing hull model was towed in a 116-m long, 8-m wide tow-tank with a water depth of 5 m. Hull models at 1/10 and 1/4 of full-scale were examined. These models, only free to move in heave and pitch, were instrumented to measure dynamic pressures with point-pressure sensors at 12 locations near the LCG (longitudinal center of gravity) and transom as well as a highly spatially resolved pressure mapping system. These pressure measurements were sampled at rates up to 20 kHz. Using these pressure measurements along with underwater photos of the wetted surface allowed for the v-shaped wetted line and stagnation line to be measured. Preliminary results show that the peak pressures occur before the wetted line and that atmospheric pressure is reached at the transom. Supported by the Office of Naval Research.

  17. Mapping optically variable quasars towards the Galactic plane

    NASA Astrophysics Data System (ADS)

    Fernandez-Trincado, J. G.; Verdugo, T.; Reylé, C.; Robin, A. C.; de Diego, J. A.; Motta, V.; Vega, L.; Downes, J. J.; Mateu, C.; Vivas, A. K.; Briceño, C.; Abad, C.; Vieira, K.; Hernández, J.; Nuñez, A.; Gatuzz, E.

    2015-12-01

    We present preliminary results of the CIDA Equatorial Variability Survey (CEVS), looking for quasar (hereafter QSO) candidates near the Galactic plane. The CEVS contains photometric data from extended and adjacent regions of the Milky Way disk (˜ 500 sq. deg.). In this work 2.5 square degrees with moderately high temporal sampling in the CEVS were analyzed. The selection of QSO candidates was based on the study of intrinsic optical photometric variability of 14,719 light curves. We studied samples defined by cuts in the variability index (V_{index}>66.5), periodicity index (Q > 2), and the distribution of these sources in the plane (A_T,γ), using a slight modification of the first-order of the structure function for the temporal sampling of the survey. Finally, 288 sources were selected as QSO candidates. The results shown in this work are a first attempt to develop a robust method to detect QSO towards the Galactic plane in the era of massive surveys such as VISTA and Gaia.

  18. Magnetic anisotropy and order structure of L10-FePt(001) single-crystal films grown epitaxially on (001) planes of MgO, SrTiO3, and MgAl2O4 substrates

    NASA Astrophysics Data System (ADS)

    Hotta, A.; Ono, T.; Hatayama, M.; Tsumura, K.; Kikuchi, N.; Okamoto, S.; Kitakami, O.; Shimatsu, T.

    2014-05-01

    L10-FePt(001) single-crystal films were grown epitaxially on SrTiO3(001), MgAl2O4(001), and MgO(001) substrates. Their uniaxial magnetic anisotropy Ku and the order structure were examined for the film thickness t range of 2-14 nm. All series of films show large Ku of 4 × 107 erg/cm3 in the thickness range higher than 10 nm, with order parameter S of 0.8 and saturation magnetization Ms of 1120 emu/cm3. Ku decreased gradually as t decreased. The Ku reduction was considerable when t decreased from 4 nm to 2 nm. No marked difference in the thickness dependence of Ku was found in any series of films, although the lattice mismatch between FePt and the substrates was markedly different. Ku reduction showed good agreement with the reduction of S for the films on MgAl2O4 and MgO. The Ku ˜ S2 plot showed an almost linear relation, which is in good agreement with theoretical predictions. Transmission electron microscopy images for a FePt film on MgO substrate revealed that the lattice mismatch between FePt(001) and MgO(001) was relaxed in the initial 1 or 2 layers of FePt(001) lattices, which is likely to be true also for two other series of films.

  19. Deep-Plane Lipoabdominoplasty in East Asians

    PubMed Central

    Jang, Jun-Young; Hong, Yoon Gi; Sim, Hyung Bo; Sun, Sang Hoon

    2016-01-01

    Background The objective of this study was to develop a new surgical technique by combining traditional abdominoplasty with liposuction. This combination of operations permits simpler and more accurate management of various abdominal deformities. In lipoabdominoplasty, the combination of techniques is of paramount concern. Herein, we introduce a new combination of liposuction and abdominoplasty using deep-plane flap sliding to maximize the benefits of both techniques. Methods Deep-plane lipoabdominoplasty was performed in 143 patients between January 2007 and May 2014. We applied extensive liposuction on the entire abdomen followed by a sliding flap through the deep plane after repairing the diastasis recti. The abdominal wound closure was completed with repair of Scarpa's fascia. Results The average amount of liposuction aspirate was 1,400 mL (700–3,100 mL), and the size of the average excised skin ellipse was 21.78×12.81 cm (from 15×10 to 25×15 cm). There were no major complications such as deep-vein thrombosis or pulmonary embolism. We encountered 22 cases of minor complications: one wound infection, one case of skin necrosis, two cases of undercorrection, nine hypertrophic scars, and nine seromas. These complications were solved by conservative management or simple revision. Conclusions The use of deep-plane lipoabdominoplasty can correct abdominal deformities more effectively and with fewer complications than traditional abdominoplasty. PMID:27462568

  20. Trajectory optimization for the National Aerospace Plane

    NASA Technical Reports Server (NTRS)

    Lu, Ping

    1993-01-01

    The objective of this second phase research is to investigate the optimal ascent trajectory for the National Aerospace Plane (NASP) from runway take-off to orbital insertion and address the unique problems associated with the hypersonic flight trajectory optimization. The trajectory optimization problem for an aerospace plane is a highly challenging problem because of the complexity involved. Previous work has been successful in obtaining sub-optimal trajectories by using energy-state approximation and time-scale decomposition techniques. But it is known that the energy-state approximation is not valid in certain portions of the trajectory. This research aims at employing full dynamics of the aerospace plane and emphasizing direct trajectory optimization methods. The major accomplishments of this research include the first-time development of an inverse dynamics approach in trajectory optimization which enables us to generate optimal trajectories for the aerospace plane efficiently and reliably, and general analytical solutions to constrained hypersonic trajectories that has wide application in trajectory optimization as well as in guidance and flight dynamics. Optimal trajectories in abort landing and ascent augmented with rocket propulsion and thrust vectoring control were also investigated. Motivated by this study, a new global trajectory optimization tool using continuous simulated annealing and a nonlinear predictive feedback guidance law have been under investigation and some promising results have been obtained, which may well lead to more significant development and application in the near future.

  1. In plane oscillation of a bifilar pendulum

    NASA Astrophysics Data System (ADS)

    Hinrichsen, Peter F.

    2016-11-01

    The line tensions, the horizontal and vertical accelerations as well as the period of large angle oscillations parallel to the plane of a bifilar suspension are presented and have been experimentally investigated using strain gauges and a smart phone. This system has a number of advantages over the simple pendulum for studying large angle oscillations, and for measuring the acceleration due to gravity.

  2. A Method for Measuring a Plane Angle.

    ERIC Educational Resources Information Center

    Roberts, George D.; Roberts, G. Gilbert

    1978-01-01

    Derivation of formulas and example problems for determining the size of a plane angle are given to help in drafting work. The authors state that a small hand calculator will provide greater accuracy in solving these problems than a protractor. (MF)

  3. Selective plane illumination microscopy on a chip.

    PubMed

    Paiè, Petra; Bragheri, Francesca; Bassi, Andrea; Osellame, Roberto

    2016-04-26

    Selective plane illumination microscopy can image biological samples at a high spatiotemporal resolution. Complex sample preparation and system alignment normally limit the throughput of the method. Using femtosecond laser micromachining, we created an integrated optofluidic device that allows obtaining continuous flow imaging, three-dimensional reconstruction and high-throughput analysis of large multicellular spheroids at a subcellular resolution.

  4. Dual band QWIP focal plane array

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D. (Inventor); Choi, Kwong Kit (Inventor); Bandara, Sumith V. (Inventor)

    2005-01-01

    A quantum well infrared photodetector (QWIP) that provides two-color image sensing. Two different quantum wells are configured to absorb two different wavelengths. The QWIPs are arrayed in a focal plane array (FPA). The two-color QWIPs are selected for readout by selective electrical contact with the two different QWIPs or by the use of two different wavelength sensitive gratings.

  5. MTI Focal Plane Assembly Design and Performance

    SciTech Connect

    Ballard, M.; Rienstra, J.L.

    1999-06-17

    The focal plane assembly for the Multispectral Thermal Imager (MTI) consists of sensor chip assemblies, optical filters, and a vacuum enclosure. Sensor chip assemblies, composed of linear detector arrays and readout integrated circuits, provide spatial resolution in the cross-track direction for the pushbroom imager. Optical filters define 15 spectral bands in a range from 0.45 {micro}m to 10.7 {micro}m. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. Three pairs of sensor chip assemblies (SCAs) are required to provide cross-track coverage in all 15 spectral bands. Each pair of SCAs includes detector arrays made from silicon, iridium antimonide, and mercury cadmium telluride. Read out integrated circuits multiplex the signals from the detectors to 18 separate video channels. Optical filter assemblies defining the spectral bands are mounted over the linear detector arrays. Each filter assembly consists of several filter strips bonded together side-by-side. The MTI focal plane assembly has been integrated with the rest of the payload and has undergone detailed testing and calibration. This paper includes representative test data for the various spectral bands and the overall performance of the focal plane assembly.

  6. Simple Harmonic Motion in Harmonic Plane Waves.

    ERIC Educational Resources Information Center

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  7. Large Format Multicolor QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Soibel, A.; Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.

    2009-01-01

    Mid-wave infrared (MWIR) and long-wave infrared (LWIR) multicolor focal plane array (FPA) cameras are essential for many DoD and NASA applications including Earth and planetary remote sensing. In this paper we summarize our recent development of large format multicolor QWIP FPA that cover MWIR and LWIR bands.

  8. Towards Dualband Megapixel QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Hill, C. J.; Rafol, S. B.; Salazar, D.; Woolaway, J.; LeVan, P. D.; Tidrow, M. Z.

    2006-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 x 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEDT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEDT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEDT, uniformity, operability, and modulation transfer functions of the 1024 x 1024 pixel arrays and the progress of dualband QWIP focal plane array development work.

  9. Microscale out-of-plane anemometer

    NASA Technical Reports Server (NTRS)

    Liu, Chang (Inventor); Chen, Jack (Inventor)

    2005-01-01

    A microscale out-of-plane thermal sensor. A resistive heater is suspended over a substrate by supports raised with respect to the substrate to provide a clearance underneath the resistive heater for fluid flow. A preferred fabrication process for the thermal sensor uses surface micromachining and a three-dimensional assembly to raise the supports and lift the resistive heater over the substrate.

  10. Respective influence of in-plane and out-of-plane spin-transfer torques in magnetization switching of perpendicular magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Timopheev, A. A.; Sousa, R.; Chshiev, M.; Buda-Prejbeanu, L. D.; Dieny, B.

    2015-09-01

    The relative contributions of in-plane (damping-like) and out-of-plane (field-like) spin-transfer torques (STT) in the magnetization switching of out-of-plane magnetized magnetic tunnel junctions (pMTJ) has been theoretically analyzed using the transformed Landau-Lifshitz-Gilbert (LLG) equation with the STT terms. It is demonstrated that in a pMTJ structure obeying macrospin dynamics, the out-of-plane torque influences the precession frequency, but it does not contribute significantly to the STT switching process (in particular to the switching time and switching current density), which is mostly determined by the in-plane STT contribution. This conclusion is confirmed by finite temperature and finite writing pulse macrospin simulations of the current field switching diagrams. It contrasts with the case of STT switching in in-plane magnetized magnetic tunnel junction (MTJ) in which the field-like term also influences the switching critical current. This theoretical analysis was successfully applied to the interpretation of voltage field STT switching diagrams experimentally measured on pMTJ pillars 36 nm in diameter, which exhibit macrospin behavior. The physical nonequivalence of Landau and Gilbert dissipation terms in the presence of STT-induced dynamics is also discussed.

  11. The three-dimensional evolution of a plane wake

    NASA Technical Reports Server (NTRS)

    Maekawa, H.; Moser, R. D.; Mansour, N. N.

    1993-01-01

    In the past three decades, linear stability analysis has led to a comprehensive understanding of the linear stages of transition in plane wakes. Our understanding of the nonlinear and turbulent stages is less developed. Nonlinear theory developed by Papageorgiou and Smith was used to study the long-wavelength regime in wakes. The nonlinear and turbulent stages were investigated experimentally, and few numerical studies examined the early nonlinear stages of forced wakes. The evolution of three dimensional disturbances in an incompressible wake is investigated using direct numerical simulations. The instantaneous three-dimaensional structures and corresponding statistics are presented.

  12. Vertical-cavity in-plane heterostructures: Physics and applications

    SciTech Connect

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2015-11-02

    We show that in-plane (lateral) heterostructures realized in vertical cavities with high contrast grating reflectors can be used to significantly modify the anisotropic dispersion curvature, also interpreted as the photon effective mass. This design freedom enables exotic configurations of heterostructures and many interesting applications. The effects of the anisotropic photon effective mass on the mode confinement, mode spacing, and transverse modes are investigated. As a possible application, the method of boosting the speed of diode lasers by engineering the photon-photon resonance is discussed. Based on this platform, we propose a system of two laterally coupled cavities, which shows the breaking of parity-time symmetry in vertical cavity structures.

  13. Domain faceting in an in-plane magnetic reorientation transition

    SciTech Connect

    Vescovo, E.; Mentes, T.O.; Sadowski, J.T.; Ablett, J.M.; Nino, M.A.; Locatelli, A.

    2010-11-04

    The microscopic structure of the 90{sup o} in-plane magnetic reorientation transition in Fe(110) films is examined using photoemission x-ray microscopy. At the nanoscale, sharp magnetic boundaries are detected. They are indicative of a first-order transition and are consistent with Fe magnetic anisotropy constants. At the micron scale, the magnetic boundary breaks up into triangular patterns whose characteristic angular dependence is revealed by experiments on conical microwedges. This effect, fully accounted by micromagnetic simulations, opens the possibility to control the sharpness of the transition at the microscopic scale.

  14. Buckled cantilevers for out-of-plane platforms

    NASA Astrophysics Data System (ADS)

    Johnstone, R. W.; Ma, A. H.; Sameoto, D.; Parameswaran, M.; Leung, A. M.

    2008-04-01

    In this paper, we show how surface-micromachined buckled cantilevers can be used to construct out-of-plane structures. We include the relevant theory necessary to predict the height and angle of plates attached to buckled cantilevers, as well as the mechanical stresses involved in assembly. These platforms can be assembled to any angle between 0° and 90° with respect to the substrate by changing the attachment point and the amount of deflection. Example devices were fabricated using PolyMUMPs™ and assembled. Using these devices, the deflection of the buckled cantilevers was verified, as well as the placement for raised platforms.

  15. Rotating plane Couette flow at high rotation number

    NASA Astrophysics Data System (ADS)

    Suryadi, A.; Tillmark, N.; Alfredsson, P. H.

    2012-11-01

    Flow structures in the rotating plane Couette flow facility at KTH (described in Tsukahara, et al. J. Fluid Mech. vol. 648) have been studied at high rotation numbers. The test section is 20 mm wide with a length of 1500 mm in the streamwise (x) and 360 mm in the spanwise (z) directions and can be rotated in the spanwise direction up to angular velocities of Ωz ~ 0 . 6 rad/s. The flow is characterised by: (1) the Reynolds number Re based on the test section's half-width (h) and half of the velocity difference between the moving walls, (2) the rotation number Ω = 2Ωzh2 / ν . For low rotation numbers the primary instability consists of streamwise-oriented roll cells, but Tsukahara, et al. showed the secondary instability in the form of wavy streamwise oriented roll-cells at Re = 100 and Ω = 3 - 12 , whereas for higher Ω, the flow structures again stabilize to streamwise-oriented roll cells. Here we find that at even higher Ω in the range 40 - 70 , a new type of secondary instability develops in the form of counter-rotating helical roll-cells. The structure of this instability, as well as other instabilities, are investigated by flow visualization as well as two-dimensional PIV-measurements in several xz -planes.

  16. Multifocal planes head-mounted displays.

    PubMed

    Rolland, J P; Krueger, M W; Goon, A

    2000-07-01

    Stereoscopic head-mounted displays (HMD's) provide an effective capability to create dynamic virtual environments. For a user of such environments, virtual objects would be displayed ideally at the appropriate distances, and natural concordant accommodation and convergence would be provided. Under such image display conditions, the user perceives these objects as if they were objects in a real environment. Current HMD technology requires convergent eye movements. However, it is currently limited by fixed visual accommodation, which is inconsistent with real-world vision. A prototype multiplanar volumetric projection display based on a stack of laminated planes was built for medical visualization as discussed in a paper presented at a 1999 Advanced Research Projects Agency workshop (Sullivan, Advanced Research Projects Agency, Arlington, Va., 1999). We show how such technology can be engineered to create a set of virtual planes appropriately configured in visual space to suppress conflicts of convergence and accommodation in HMD's. Although some scanning mechanism could be employed to create a set of desirable planes from a two-dimensional conventional display, multiplanar technology accomplishes such function with no moving parts. Based on optical principles and human vision, we present a comprehensive investigation of the engineering specification of multiplanar technology for integration in HMD's. Using selected human visual acuity and stereoacuity criteria, we show that the display requires at most 27 equally spaced planes, which is within the capability of current research and development display devices, located within a maximal 26-mm-wide stack. We further show that the necessary in-plane resolution is of the order of 5 microm.

  17. Determining the ice-binding planes of antifreeze proteins by fluorescence-based ice plane affinity.

    PubMed

    Basu, Koli; Garnham, Christopher P; Nishimiya, Yoshiyuki; Tsuda, Sakae; Braslavsky, Ido; Davies, Peter

    2014-01-15

    Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice through their ice-binding surfaces. Fluorescence-based ice plane affinity (FIPA) analysis is a modified technique used to determine the ice planes to which the AFPs bind. FIPA is based on the original ice-etching method for determining AFP-bound ice-planes. It produces clearer images in a shortened experimental time. In FIPA analysis, AFPs are fluorescently labeled with a chimeric tag or a covalent dye then slowly incorporated into a macroscopic single ice crystal, which has been preformed into a hemisphere and oriented to determine the a- and c-axes. The AFP-bound ice hemisphere is imaged under UV light to visualize AFP-bound planes using filters to block out nonspecific light. Fluorescent labeling of the AFPs allows real-time monitoring of AFP adsorption into ice. The labels have been found not to influence the planes to which AFPs bind. FIPA analysis also introduces the option to bind more than one differently tagged AFP on the same single ice crystal to help differentiate their binding planes. These applications of FIPA are helping to advance our understanding of how AFPs bind to ice to halt its growth and why many AFP-producing organisms express multiple AFP isoforms.

  18. Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity

    PubMed Central

    Basu, Koli; Garnham, Christopher P.; Nishimiya, Yoshiyuki; Tsuda, Sakae; Braslavsky, Ido; Davies, Peter

    2014-01-01

    Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice through their ice-binding surfaces. Fluorescence-based ice plane affinity (FIPA) analysis is a modified technique used to determine the ice planes to which the AFPs bind. FIPA is based on the original ice-etching method for determining AFP-bound ice-planes. It produces clearer images in a shortened experimental time. In FIPA analysis, AFPs are fluorescently labeled with a chimeric tag or a covalent dye then slowly incorporated into a macroscopic single ice crystal, which has been preformed into a hemisphere and oriented to determine the a- and c-axes. The AFP-bound ice hemisphere is imaged under UV light to visualize AFP-bound planes using filters to block out nonspecific light. Fluorescent labeling of the AFPs allows real-time monitoring of AFP adsorption into ice. The labels have been found not to influence the planes to which AFPs bind. FIPA analysis also introduces the option to bind more than one differently tagged AFP on the same single ice crystal to help differentiate their binding planes. These applications of FIPA are helping to advance our understanding of how AFPs bind to ice to halt its growth and why many AFP-producing organisms express multiple AFP isoforms. PMID:24457629

  19. Initial Operation of S-Band Plane Wave Transformer Photoinjector

    NASA Astrophysics Data System (ADS)

    Ding, Xiaodong; Pellegrini, Claudio; Rosenzweig, James; Telfer, Soren; Physics, Dept Of; Astronomy Team

    2000-04-01

    An integrated S-Band RF photoinjector based on the plane wave transformer (PWT) is being built and operated in the Particle Beam Physics Laboratory at UCLA. This novel structure integrates a photocathode directly into a PWT Linac making the structure simple and compact. Due to the strong coupling between each adjacent cell, this structure is relatively easy to fabricate and operate. This photoinjector can provide high brightness beams at energies of 15 to 20MeV, with emittance less than 1mm-mrad at charge of 1 nC. These short-pulse beams can be used in various applications: space charge dominated beam physics studies, plasma lenses, plasma accelerators, free-electron laser microbunching techniques, and SASE-FEL physics studies. It will also provide commercial opportunities in chemistry, biology and medicine. The initial operation of the PWT photoinjector with high RF power is described. A comparation of experimental result and theoretical design is also discussed.

  20. The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: structure and lubrication performance.

    PubMed

    Wang, Min; Zander, Thomas; Liu, Xiaoyan; Liu, Chao; Raj, Akanksha; Wieland, D C Florian; Garamus, Vasil M; Willumeit-Römer, Regine; Claesson, Per Martin; Dėdinaitė, Andra

    2015-05-01

    Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25-52°C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica-liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25°C and 39°C and in the liquid disordered state at 55°C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37°C.

  1. Innovative design of composite structures: Design, manufacturing, and testing of plates utilizing curvilinear fiber trajectories

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Rust, R. J.; Waters, W. A., Jr.

    1994-01-01

    As a means of improving structural design, the concept of fabricating flat plates containing holes by incorporating curvilinear fiber trajectories to transmit loads around the hole is studied. In the present discussion this concept is viewed from a structural level, where access holes, windows, doors, and other openings are of significant size. This is opposed to holes sized for mechanical fasteners. Instead of cutting the important load-bearing fibers at the hole edge, as a conventional straightline design does, the curvilinear design preserves the load-bearing fibers by orienting them in smooth trajectories around the holes, their loading not ending abruptly at the hole edge. Though the concept of curvilinear fiber trajectories has been studied before, attempts to manufacture and test such plates have been limited. This report describes a cooperative effort between Cincinnati Milacron Inc., NASA Langley Research Center, and Virginia Polytechnic Institute and State University to design, manufacture, and test plates using the curvilinear fiber trajectory concept. The paper discusses details of the plate design, details of the manufacturing, and a summary of results from testing the plates with inplane compressive buckling loads and tensile loads. Comparisons between the curvilinear and conventional straightline fiber designs based on measurements and observation are made. Failure modes, failure loads, strains, deflections, and other key responses are compared.

  2. VAST PLANES OF SATELLITES IN A HIGH-RESOLUTION SIMULATION OF THE LOCAL GROUP: COMPARISON TO ANDROMEDA

    SciTech Connect

    Gillet, N.; Ocvirk, P.; Aubert, D.; Knebe, A.; Yepes, G.; Libeskind, N.; Gottlöber, S.; Hoffman, Y.

    2015-02-10

    We search for vast planes of satellites (VPoS) in a high-resolution simulation of the Local Group performed by the CLUES project, which improves significantly the resolution of previous similar studies. We use a simple method for detecting planar configurations of satellites, and validate it on the known plane of M31. We implement a range of prescriptions for modeling the satellite populations, roughly reproducing the variety of recipes used in the literature, and investigate the occurrence and properties of planar structures in these populations. The structure of the simulated satellite systems is strongly non-random and contains planes of satellites, predominantly co-rotating, with, in some cases, sizes comparable to the plane observed in M31 by Ibata et al. However, the latter is slightly richer in satellites, slightly thinner, and has stronger co-rotation, which makes it stand out as overall more exceptional than the simulated planes, when compared to a random population. Although the simulated planes we find are generally dominated by one real structure forming its backbone, they are also partly fortuitous and are thus not kinematically coherent structures as a whole. Provided that the simulated and observed planes of satellites are indeed of the same nature, our results suggest that the VPoS of M31 is not a coherent disk and that one-third to one-half of its satellites must have large proper motions perpendicular to the plane.

  3. Varied line spacing plane holographic grating recorded by using uniform line spacing plane gratings.

    PubMed

    Qing, Ling; Gang, Wu; Bin, Liu; Qiuping, Wang

    2006-07-20

    Uniform line spacing plane gratings are introduced into a recording system to generate aspherical wavefronts for recording varied line spacing plane holographic gratings. Analytical expressions of groove parameters are derived to the fourth order. A ray-tracing validation algorithm is provided based on Fermat's principle and a local search method. The recording parameters are optimized to record a varied line spacing plane holographic grating with the aid of derived analytical expressions. A design example demonstrates the exactness of the analytical expressions and the superiority of recording optics with auxiliary gratings. PMID:16826244

  4. Out-of-plane Block Copolymer Microdomains in High Aspect-Ratio Templates

    NASA Astrophysics Data System (ADS)

    Gadelrab, Karim; Bai, Wubin; Alexander-Katz, Alfredo; Ross, Caroline

    The use of directed self-assembly DSA of block copolymers BCP proved to be a power approach for nanoscale fabrication. It combines the ability of BCPs to self-assemble into nanoscale features with the use of lithographic tools to create controlled long range order. In addition, BCP with highly incompatible blocks (high Flory-Huggins interaction parameter (χ)) offer improvement in resolution, and line edge fluctuations of the self-assembled patterns. Unfortunately, high- χ BCPs usually exhibit large differences in surface affinity between the two blocks, leading to the formation of a surface layer of the lower surface energy block and favoring in-plane orientation of lamellae or cylindrical microdomains. Here, we explore the conditions under which a high χ BCP creates an out-of-plane lamellar structure using functionalized high aspect ratio trenches with preferential walls. We employ the free energy analysis of self-consistent field theory SCFT to identify whether an in-plane or out-of-plane structure is stable for a particular trench width. In addition, we employ the single mode expansion of Ginzburg-Landau free energy expression in the weak segregation limit to analytically construct a phase diagram of the in-plane and out-of-plane lamellae as a function of aspect ratio and surface attraction strength. It is found that achieving an out of plane lamellar structure necessitates a coupling between aspect ratio and surface functionality. In particular, strong side wall attraction results in out-of-plane lamellae when the trench aspect ratio is greater than unity. The results are validated for a lamellar forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) within trenches made using interference lithography.

  5. The supergalactic plane revisited with the Optical Redshift Survey

    NASA Astrophysics Data System (ADS)

    Lahav, O.; Santiago, B. X.; Webster, A. M.; Strauss, Michael A.; Davis, M.; Dressler, A.; Huchra, J. P.

    2000-02-01

    We re-examine the existence and extent of the planar structure in the local galaxy density field, the so-called supergalactic plane (SGP). This structure is studied here in three dimensions using both the new Optical Redshift Survey (ORS) and the IRAS 1.2-Jy redshift survey. The density contrast in a slab of thickness 20h-1Mpc and diameter 80Mpc aligned with the standard de Vaucouleurs supergalactic coordinates is δsgp~0.5 for both ORS and IRAS. The structure of the SGP is not well described by a homogeneous ellipsoid, although it does appear to be a flattened structure, which we quantify by calculating the moment of inertia tensor of the density field. The directions of the principal axes vary with radius, but the minor axis remains within θz~30 deg of the standard SGP Z-axis, out to a radius of 80h-1Mpc, for both ORS and IRAS. However, the structure changes shape with radius, varying between a flattened pancake and a dumbbell, the latter at a radius of ~50h-1Mpc, where the Great Attractor and Perseus-Pisces superclusters dominate the distribution. This calls to question the connectivity of the `plane' beyond ~40h-1Mpc. The configuration found here can be viewed as part of a web of filaments and sheets, rather than as an isolated pancake-like structure. An optimal minimum variance reconstruction of the density field using Wiener filtering, which corrects for both redshift distortion and shot noise, yields a similar misalignment angle and behaviour of axes. The background-independent statistic of axes proposed here can be best used for testing cosmological models by comparison with N-body simulations.

  6. Polar flexoelectric in-plane and out-of-plane switching in bent core nematic mixtures

    NASA Astrophysics Data System (ADS)

    Elamain, Omaima; Hegde, Gurumurthy; Komitov, Lachezar

    2016-07-01

    Polar electro-optic response, arising from the coupling between an applied in-plane and out-of-plane dc electric field, respectively, and the flexoelectric polarization of bent core nematic liquid crystal mixtures with hybrid alignment is studied in conventional sandwich cells with homeotropic anchoring at one of the cell substrates and planar at the other. Such a hybrid alignment, however, results in a splay/bend elastic deformation of the nematic giving rise of a flexoelectric polarization. It was found that a pronounced polar electro-optic response, both in-plane and out of plane, took place in the bent core nematic mixtures at very low voltages due to the high flexoelectric polarization in these mixtures, compared with the one observed in calamitic liquid crystals.

  7. In-plane vibrations of a rectangular plate: Plane wave expansion modelling and experiment

    NASA Astrophysics Data System (ADS)

    Arreola-Lucas, A.; Franco-Villafañe, J. A.; Báez, G.; Méndez-Sánchez, R. A.

    2015-04-01

    Theoretical and experimental results for in-plane vibrations of a uniform rectangular plate with free boundary conditions are obtained. The experimental setup uses electromagnetic-acoustic transducers and a vector network analyzer. The theoretical calculations were obtained using the plane wave expansion method applied to the in-plane thin plate vibration theory. The agreement between theory and experiment is excellent for the lower 95 modes covering a very wide frequency range from DC to 20 kHz. Some measured normal-mode wave amplitudes were compared with the theoretical predictions; very good agreement was observed. The excellent agreement of the classical theory of in-plane vibrations confirms its reliability up to very high frequencies

  8. Intraoperative tracking of aortic valve plane

    PubMed Central

    Nguyen, Duc Long Hung; Garreau, Mireille; Auffret, Vincent; Le Breton, Hervé; Verhoye, Jean-Philippe; Haigron, Pascal

    2013-01-01

    The main objective of this work is to track the aortic valve plane in intra-operative fluoroscopic images in order to optimize and secure Transcatheter Aortic Valve Implantation (TAVI) procedure. This paper is focused on the issue of aortic valve calcifications tracking in fluoroscopic images. We propose a new method based on the Tracking-Learning-Detection approach, applied to the aortic valve calcifications in order to determine the position of the aortic valve plane in intra-operative TAVI images. This main contribution concerns the improvement of object detection by updating the recursive tracker in which all features are tracked jointly. The approach has been evaluated on four patient databases, providing an absolute mean displacement error less than 10 pixels ≈ 2mm). Its suitability for the TAVI procedure has been analyzed. PMID:24110703

  9. The national aero-space plane

    NASA Technical Reports Server (NTRS)

    Mendez, Bruce

    1988-01-01

    The National Aerospace Plane is an extremely versatile and adaptable aircraft. It can be developed into an Orient Express that would dramatically improve trade with countries in Asia and elsewhere: a commuter transport to ferry men and materials to space, an advanced tactical fighter or bomber, and an unparalleled high altitude spy-plane to observe troubled spots all over the globe. Utilizing the technology developed by this pilot program, it will be possible to quickly and easily get to low Earth orbit, go halfway around the world in a fraction of the time it previously took, and lead the world in the development of advanced technology to improve our lives and the lives of many others.

  10. A conceptual study of Japan's rocket plane

    NASA Astrophysics Data System (ADS)

    Shibato, Yoji; Fukushima, Yukio; Miwada, Makoto

    1989-10-01

    NASDA's H-II Orbiting Plane, designated 'HOPE', is an unmanned winged vehicle that is to be launched as the upper stage of the H-II rocket. HOPE is currently in its conceptual development stage, and is expected to become operational at the end of the 1990s. As payloads increase, HOPE will be lofted atop launch vehicles that add solid-rocket boosters or more powerful LH2/LOX liquid-fueled rocket lower stages to the H-II baseline; HOPE payloads 1.5-3 times greater than those typical of the H-II baseline will then become possible. A preliminary design projection is made for a next-generation, reusable 'rocket-plane'.

  11. The Focal Plane Package for Solar B

    NASA Astrophysics Data System (ADS)

    Title, A.; Tsuneta, S.

    The Focal Plane Package (FPP) of the JAXA Solar B Solar Optical Telescope (SOT) combines an advanced version of Stokes Polarimeter, a tunable birefringent filter, and a set of narrow spectral filters. The Stokes Polarimeter and the filter systems can operate simultaneously allowing the construction of precise vector magnetograms and images in a range of spectral lines. Both the Stokes Polarimeter and the filter systems have controllable fields of view and cadence. A local correlation tracker in the FFP operates a high speed tip-tilt mirror to stabilize the image in all focal planes. The time sequences of precise vector magnetic maps uncompromised by seeing will enable new understanding of how flux emerges through and disappears from the solar surface. The tunable filter can measure the flows in the atmosphere from the lower photosphere through the Chromosphere enabling new insights in the magneto-hydrodynamics of magnetic evolution.

  12. Image-plane processing of visual information

    NASA Technical Reports Server (NTRS)

    Huck, F. O.; Fales, C. L.; Park, S. K.; Samms, R. W.

    1984-01-01

    Shannon's theory of information is used to optimize the optical design of sensor-array imaging systems which use neighborhood image-plane signal processing for enhancing edges and compressing dynamic range during image formation. The resultant edge-enhancement, or band-pass-filter, response is found to be very similar to that of human vision. Comparisons of traits in human vision with results from information theory suggest that: (1) Image-plane processing, like preprocessing in human vision, can improve visual information acquisition for pattern recognition when resolving power, sensitivity, and dynamic range are constrained. Improvements include reduced sensitivity to changes in lighter levels, reduced signal dynamic range, reduced data transmission and processing, and reduced aliasing and photosensor noise degradation. (2) Information content can be an appropriate figure of merit for optimizing the optical design of imaging systems when visual information is acquired for pattern recognition. The design trade-offs involve spatial response, sensitivity, and sampling interval.

  13. Split-field pupil plane determination apparatus

    DOEpatents

    Salmon, Joseph T.

    1996-01-01

    A split-field pupil plane determination apparatus (10) having a wedge assembly (16) with a first glass wedge (18) and a second glass wedge (20) positioned to divide a laser beam (12) into a first laser beam half (22) and a second laser beam half (24) which diverge away from the wedge assembly (16). A wire mask (26) is positioned immediately after the wedge assembly (16) in the path of the laser beam halves (22, 24) such that a shadow thereof is cast as a first shadow half (30) and a second shadow half (32) at the input to a relay telescope (14). The relay telescope (14) causes the laser beam halves (22, 24) to converge such that the first shadow half (30) of the wire mask (26) is aligned with the second shadow half (32) at any subsequent pupil plane (34).

  14. Tilt plane orientation in antiferroelectric liquid crystal cells and the origin of the pretransitional effect.

    PubMed

    Rudquist, P; Lagerwall, J P F; Meier, J G; D'havé, K; Lagerwall, S T

    2002-12-01

    The optic, electro-optic, and dielectric properties of antiferroelectric liquid crystals (AFLCs) are analyzed and discussed in terms of the local tilt plane orientation. We show that the so-called pretransitional effect is a combination of two different electro-optic modes: the field-induced antiphase distortion of the antiferroelectric structure and the field-induced reorientation of the tilt plane. In the presence of a helix, the latter corresponds to a field-induced distortion of the helix. Both electro-optic modes are active only when the electric field has a component along the tilt plane. Thus, by assuring a horizontal surface-stabilized condition, where the helix is unwound by surface action and the tilt plane is everywhere parallel to the cell plates, the pretransitional effect should be suppressed. We also discuss the dielectrically active modes in AFLCs and under which circumstances they contribute to the measured dielectric permittivity. PMID:12513306

  15. Estimation of vocal fold plane in 3D CT images for diagnosis of vocal fold abnormalities.

    PubMed

    Hewavitharanage, Sajini; Gubbi, Jayavardhana; Thyagarajan, Dominic; Lau, Ken; Palaniswami, Marimuthu

    2015-01-01

    Vocal folds are the key body structures that are responsible for phonation and regulating air movement into and out of lungs. Various vocal fold disorders may seriously impact the quality of life. When diagnosing vocal fold disorders, CT of the neck is the commonly used imaging method. However, vocal folds do not align with the normal axial plane of a neck and the plane containing vocal cords and arytenoids does vary during phonation. It is therefore important to generate an algorithm for detecting the actual plane containing vocal folds. In this paper, we propose a method to automatically estimate the vocal fold plane using vertebral column and anterior commissure localization. Gray-level thresholding, connected component analysis, rule based segmentation and unsupervised k-means clustering were used in the proposed algorithm. The anterior commissure segmentation method achieved an accuracy of 85%, a good estimate of the expert assessment. PMID:26736949

  16. A direct in vivo measurement of the three-dimensional orientation of the occlusal plane and of the sagittal discrepancy of the jaws.

    PubMed

    Ferrario, Virgilio F.; Sforza, Chiarella; Serrao, Graziano; Ciusa, Veronica

    2000-02-01

    The aim of the present investigation was to three dimensionally assess craniofacial relationships in vivo. Specifically, by using a non-invasive direct technique, the following measurements were made: 1) natural head position relative to the ground; 2) orientation of the occlusal plane relative to the subject's intrinsic facial planes; and 3) anteroposterior discrepancy of the dental bases, taking into consideration all the facial hard- and soft-tissue structures. Several dental and soft-tissue facial landmarks were directly digitized from 24 adult healthy volunteers with Angle Class I occlusions by means of an electromagnetic three-dimensional computerized digitizer. In natural head position, the three-dimensional orientation of Camper's, occlusal, and mandibular planes were measured along with the anteroposterior maxillo-mandibular discrepancies. In the frontal plane projection, all the measured planes appeared about horizontal. In the lateral plane projection, on average, Camper's plane deviated from the true horizontal by approximately 18 degrees (in a 'head flexed' direction). The occlusal plane deviated from the same horizontal by about 14 degrees, while the mandibular plane had a steeper inclination (about 30 degrees ); both planes were significantly correlated to Camper's plane. The measurements of anteroposterior jaw discrepancy revealed a wide range of sagittal relationships in the analyzed subjects. The method was found to be repeatable and fast. This direct three-dimensional in vivo assessment of the orientation of occlusal plane relative to the other facial planes could allow for a more comprehensive analysis of maxillo-mandibular sagittal discrepancies.

  17. Strings in plane wave backgrounds reexamined

    SciTech Connect

    Jofre, O.; Nunez, C. Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires )

    1994-10-15

    String theory in an exact plane wave background is explored. The four-tachyon scattering amplitude is constructed. The spectrum of states found from the poles in the factorization turns out to be equivalent to that of the theory in flat space-time. The massless vertex operator is obtained from the residue of the first order pole. It exhibits nontrivial modifications with respect to the flat space case.

  18. The Kepler photometer focal plane array

    NASA Astrophysics Data System (ADS)

    Argabright, V. S.; VanCleve, J. E.; Bachtell, E. E.; Hegge, M. J.; McArthur, S. P.; Dumont, F. C.; Rudeen, A. C.; Pullen, J. L.; Teusch, D. A.; Tennant, D. S.; Atcheson, P. D.

    2008-07-01

    The Kepler instrument is designed to detect Earth size planets in the "habitable zone" orbiting 9plane array resulting in ~13° diameter FOV, so that greater than 100,000 suitable stars in the FOV are continuously monitored over a three and a half year mission. Detection of planetary transits is made possible through 20 ppm differential photometry using pixel data from a focal plane array specifically developed for Kepler. The Kepler focal plane array is suspended above the primary mirror and consists of twenty one 2K x 2K Science CCD modules mounted on a curved Invar substrate with four output taps per module. Four fine guidance sensor (FGS) CCD modules are mounted to the corners of the Invar substrate to gather additional pointing information for the Attitude Control System in order to attain the required <2.5 milli-pixel pointing accuracy. A space staring radiator and a closed loop thermal control system maintains the CCD module temperatures at -85°C with <10mK thermal stability. Low noise electronics reads out both the Science and FGS CCD modules at a 3 MHz pixel rate. In order to achieve a 4-sigma detection of an Earth-sized planet orbiting a 12th magnitude Sun-like star, the overall noise budget allocates 150 e- to the read noise of each Science CCD module output. This paper discusses key elements of the Kepler focal plane array design, development, characterization and performance results.

  19. Marine terraces; datum planes for study of structural deformation

    USGS Publications Warehouse

    Huber, N.K.

    1975-01-01

    Along the earthquake-prone coastal area of north-central California, geologists are searching for criteria to establish the nature, extent, and rate of crustal movement or deformation that may be related to activity along known or postulated faults. This search has led to a study of marine terraces along the coast between San Francisco and Santa Cruz in the area that is transected by the Seal Cove-San Gregorio-Palo Colorado fault, a branch of the San Andreas fault system. 

  20. NASA's Structure and Evolution of the Universe focal plane directions

    NASA Astrophysics Data System (ADS)

    Schwartz, P. C.

    2004-01-01

    The SEU theme encompasses an extremely diverse area of space science. Recent roadmapping efforts been devoted to prioritizing science challenges rather than defining all that is contained in the SEU theme. The highest priorities are the Big Bang and a look at Black Holes and the regions near them. To support these challenges the following technologies are of high priority: Cryogenic Systems, Formation Flying, High Performance Optics: Mid- and Far-IR Optics, X-Ray/UV optics, Advanced Detectors: X-ray and Submm/Far IR, Energy resolving detectors and Large Format Arrays. The initiative, Beyond Einstein, includes baseline missions that utilize technologies that are generally at a laboratory proof of concept level. Technology development plans are established for the flagship missions: Con-X and LISA. Conceptual development is still progressing for some Einstein Probe missions. Vision missions are still in conceptual development.

  1. Dynamics of coherent structures in a plane mixing layer

    NASA Technical Reports Server (NTRS)

    Hussain, Fazle; Moser, R. D.; Colonius, T.; Moin, P.; Rogers, M. M.

    1988-01-01

    An incompressible, time developing 3-D mixing layer with idealized initial conditions was simulated numerically. Consistent with the suggestions from experimental measurements, the braid region between the dominant spanwise vortices or rolls develops longitudinal vortices or ribs, which are aligned upstream and downstream of a roll and produce spanwise distortion of the rolls. The process by which this distortion occurs is explained by studying a variety of quantities of dynamic importance (e.g., production of enstrophy, vortex stretching). Other quantities of interest (dissipation, helicity density) are also computed and discussed. The currently available simulation only allows the study of the early evolution (before pairing) of the mixing layer. New simulations in progress will relieve this restriction.

  2. 26Al Emission Structure Along the Galactic Plane

    NASA Technical Reports Server (NTRS)

    Purcell, William R.

    1996-01-01

    During the grant period (February 1995 - February 1996), the NU team members worked to analyze the available data. Results of this analysis were presented at the 24(th) international Cosmic Ray Conference held in Rome, Italy, August 28 - September 8, 1995, and at the 1996 meeting of the AAS/High Energy Astrophysics Division held in San Diego, California, April 30 - May 3, 1996. The results were also published in the conference proceedings of the Cosmic Ray Conference. As a result of this work, subsequent proposals have been submitted to continue this effort and to develop enhanced capabilities for OSSE observations of high energy emission.

  3. Studies on an aerial propellant transfer space plane (APTSP)

    NASA Astrophysics Data System (ADS)

    Jayan, N.; Biju Kumar, K. S.; Gupta, Anish Kumar; Kashyap, Akhilesh Kumar; Venkatraman, Kartik; Mathew, Joseph; Mukunda, H. S.

    2004-04-01

    This paper presents a study of a fully reusable earth-to-orbit launch vehicle concept with horizontal take-off and landing, employing a turbojet engine for low speed, and a rocket for high-speed acceleration and space operations. This concept uses existing technology to the maximum possible extent, thereby reducing development time, cost and effort. It uses the experience in aerial filling of military aircrafts for propellant filling at an altitude of 13 km at a flight speed of M=0.85. Aerial filling of propellant reduces the take-off weight significantly thereby minimizing the structural weight of the vehicle. The vehicle takes off horizontally and uses turbojet engines till the end of the propellant filling operation. The rocket engines provide thrust for the next phase till the injection of a satellite at LEO. A sensitivity analysis of the mission with respect to rocket engine specific impulse and overall vehicle structural factor is also presented in this paper. A conceptual design of space plane with a payload capability of 10 ton to LEO is carried out. The study shows that the realization of an aerial propellant transfer space plane is possible with limited development of new technology thus reducing the demands on the finances required for achieving the objectives.

  4. Geometry of state space in plane Couette flow

    NASA Astrophysics Data System (ADS)

    Cvitanović, P.; Gibson, J. F.

    A large conceptual gap separates the theory of low-dimensional chaotic dynamics from the infinite-dimensional nonlinear dynamics of turbulence. Recent advances in experimental imaging, computational methods, and dynamical systems theory suggest a way to bridge this gap in our understanding of turbulence. Recent discoveries show that recurrent coherent structures observed in wall-bounded shear flows (such as pipes and plane Couette flow) result from close passes to weakly unstable invariant solutions of the Navier-Stokes equations. These 3D, fully nonlinear solutions (equilibria, traveling waves, and periodic orbits) structure the state space of turbulent flows and provide a skeleton for analyzing their dynamics. We calculate a hierarchy of invariant solutions for plane Couette, a canonical wall-bounded shear flow. These solutions reveal organization in the flow's turbulent dynamics and can be used to predict directly from the fundamental equations physical quantities such as bulk flow rate and mean wall drag. All results and the code that generates them are disseminated through through our group's open-source CFD software and solution database Channelflow.org and the collaborative e-book ChaosBook.org.

  5. Focal plane scanner with reciprocating spatial window

    NASA Technical Reports Server (NTRS)

    Mao, Chengye (Inventor)

    2000-01-01

    A focal plane scanner having a front objective lens, a spatial window for selectively passing a portion of the image therethrough, and a CCD array for receiving the passed portion of the image. All embodiments have a common feature whereby the spatial window and CCD array are mounted for simultaneous relative reciprocating movement with respect to the front objective lens, and the spatial window is mounted within the focal plane of the front objective. In a first embodiment, the spatial window is a slit and the CCD array is one-dimensional, and successive rows of the image in the focal plane of the front objective lens are passed to the CCD array by an image relay lens interposed between the slit and the CCD array. In a second embodiment, the spatial window is a slit, the CCD array is two-dimensional, and a prism-grating-prism optical spectrometer is interposed between the slit and the CCD array so as to cause the scanned row to be split into a plurality of spectral separations onto the CCD array. In a third embodiment, the CCD array is two-dimensional and the spatial window is a rectangular linear variable filter (LVF) window, so as to cause the scanned rows impinging on the LVF to be bandpass filtered into spectral components onto the CCD array through an image relay lens interposed between the LVF and the CCD array.

  6. The European Galactic Plane Surveys: EGAPS

    NASA Astrophysics Data System (ADS)

    Groot, P. J.; Drew, J.; Greimel, R.; Gaensicke, B.; Knigge, C.; Irwin, M.; Mampaso, A.; Augusteijn, T.; Morales-Rueda, L.; Barlow, M.; Iphas Collaboration; Uvex Collaboration; Vphas+ Collaboration

    2006-08-01

    Introduction: The European Galactic Plane Surveys (EGAPS) will for the first time ever map the complete galactic plane (10x360 degrees) down to 21st magnitude in u', g', r', i' and H-alpha and partly in He I 5875. It will complete a database of ~1 billion objects. The aim of EGAPS is to study populations of short-lived stellar and binary phases in our Galaxy and combine these population studies with stellar and binary evolutionary codes to vastly improve our understanding of crucial phases of stellar evolution. Target populations include Wolf-Rayet stars, planetary nebulae, white dwarfs (in binaries), cataclysmic variables and other mass-transferring binaries. Methods: EGAPS is using the INT+WFC on La Palma for the Northern Hemisphere and will use the VST+Omegacam in the Southern Hemisphere. Results: The Northern red survey (IPHAS, using r', i', and Halpha) has started in 2003 and is currently 70% complete. The northern blue survey (UVEX; u',g',r' and HeI) has started in June 2006. Results include the detection of a number of rare planetary nebulae, cataclysmic variables, red-dwarf white dwarf binaries in clusters, a possible AM CVn candidate, and a deep photometric and spectroscopic investigation of the Cyg X region. Discussion: EGAPS will revolutionize the field of galactic stellar astrophysics by completing the first ever digital, multicolour survey of the Galactic Plane.

  7. Hamiltonian maps in the complex plane

    SciTech Connect

    Greene, J.M.; Percival, I.C.

    1981-01-01

    Following Arnol'd's proof of the KAM theorem, an analogy with the vertical pendulum, and some general arguments concerning maps in the complex plane, detailed calculations are presented and illustrated graphically for the standard map at the golden mean frequency. The functional dependence of the coordinate q on the canonical angle variable theta is analytically continued into the complex theta-plane, where natural boundaries are found at constant absolute values of Im theta. The boundaries represent the appearance of chaotic motion in the complex plane. Two independent numerical methods based on Fourier analysis in the angle variable were used, one based on a variation-annihilation method and the other on a double expansion. The results were further checked by direct solution of the complex equations of motion. The numerically simpler, but intrinsically complex, semipendulum and semistandard map are also studied. We conjecture that natural boundaries appear in the analogous analytic continuation of the invariant tori or KAM surfaces of general nonintegrable systems.

  8. Blackfolds, plane waves and minimal surfaces

    NASA Astrophysics Data System (ADS)

    Armas, Jay; Blau, Matthias

    2015-07-01

    Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

  9. Locomotion of granulocytes on an inclined plane.

    PubMed

    Doroszewski, J; Lewandowska, K; Wierzbicki, W

    1986-01-01

    The paper presents a quantitative study of the trajectories of rat granulocytes (PMNs) migrating on a glass surface inclined at various angles, i.e. under the action of gravitational force component parallel to the plane. The action of the force of the order of 5 X 10(-13) N (component parallel to the plane inclined at 80 degrees) accompanied by the decrease of a gravitational component perpendicular to the surface does not disrupt the adhesion contact of migrating PMNs with the serum coated glass surface. Under the action of the external force parallel to the surface, the PMNs exhibit a tendency to migrate in the direction of the force vector and the angles between elementary segments (steps) of cell trajectories are smaller in comparison with migration on a horizontal plane (0 degrees inclination). It has been found that the mean velocity of motion of PMNs locomoting on a steep slope (70 degrees and 80 degrees) is greater in comparison with the migration velocity on a horizontal surface. The increase of velocity concerns not only cells migrating in the downward direction, but also those which move upwards. Possible mechanisms of the influence of external force on direction and rate of migration of granulocytes are discussed, namely modification of adhesion force, stimulation of cell motile activity, individual variability of cell adhesive and migration properties, shortening of transient locomotory adhesions.

  10. Linearized motion estimation for articulated planes.

    PubMed

    Datta, Ankur; Sheikh, Yaser; Kanade, Takeo

    2011-04-01

    In this paper, we describe the explicit application of articulation constraints for estimating the motion of a system of articulated planes. We relate articulations to the relative homography between planes and show that these articulations translate into linearized equality constraints on a linear least-squares system, which can be solved efficiently using a Karush-Kuhn-Tucker system. The articulation constraints can be applied for both gradient-based and feature-based motion estimation algorithms and to illustrate this, we describe a gradient-based motion estimation algorithm for an affine camera and a feature-based motion estimation algorithm for a projective camera that explicitly enforces articulation constraints. We show that explicit application of articulation constraints leads to numerically stable estimates of motion. The simultaneous computation of motion estimates for all of the articulated planes in a scene allows us to handle scene areas where there is limited texture information and areas that leave the field of view. Our results demonstrate the wide applicability of the algorithm in a variety of challenging real-world cases such as human body tracking, motion estimation of rigid, piecewise planar scenes, and motion estimation of triangulated meshes.

  11. Restoring Aperture Profile At Sample Plane

    SciTech Connect

    Jackson, J L; Hackel, R P; Lungershausen, A W

    2003-08-03

    Off-line conditioning of full-size optics for the National Ignition Facility required a beam delivery system to allow conditioning lasers to rapidly raster scan samples while achieving several technical goals. The main purpose of the optical system designed was to reconstruct at the sample plane the flat beam profile found at the laser aperture with significant reductions in beam wander to improve scan times. Another design goal was the ability to vary the beam size at the sample to scan at different fluences while utilizing all of the laser power and minimizing processing time. An optical solution was developed using commercial off-the-shelf lenses. The system incorporates a six meter relay telescope and two sets of focusing optics. The spacing of the focusing optics is changed to allow the fluence on the sample to vary from 2 to 14 Joules per square centimeter in discrete steps. More importantly, these optics use the special properties of image relaying to image the aperture plane onto the sample to form a pupil relay with a beam profile corresponding almost exactly to the flat profile found at the aperture. A flat beam profile speeds scanning by providing a uniform intensity across a larger area on the sample. The relayed pupil plane is more stable with regards to jitter and beam wander. Image relaying also reduces other perturbations from diffraction, scatter, and focus conditions. Image relaying, laser conditioning, and the optical system designed to accomplish the stated goals are discussed.

  12. Infrared fiber optic focal plane dispersers

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.

    1981-01-01

    Far infrared transmissive fiber optics as a component in the design of integrated far infrared focal plane array utilization is discussed. A tightly packed bundle of fibers is placed at the focal plane, where an array of infrared detectors would normally reside, and then fanned out in two or three dimensions to individual detectors. Subsequently, the detectors are multiplexed by cryogenic electronics for relay of the data. A second possible application is frequency up-conversion (v sub 1 + v sub 2 = v sub 3), which takes advantage of the nonlinear optical index of refraction of certain infrared transmissive materials in fiber form. Again, a fiber bundle is utilized as above, but now a laser of frequency v sub 1 is mixed with the incoming radiation of frequency v sub 1 within the nonlinear fiber material. The sum, v sub 2 is then detected by near infrared or visible detectors which are more sensitive than those available at v sub 2. Due to the geometrical size limitations of detectors such as photomultipliers, the focal plane dispersal technique is advantageous for imaging up-conversion.

  13. Design and analysis of multifunctional structures for embedded electronics in unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Kothari, Rushabh M.

    Multifunctional structures are a new trend in the aerospace industry for the next generation structural design. Many future structures are expected to be something in addition to a load bearing structure. The design and analysis of multifunctional structures combining structural, electrical and thermal functionalities are presented here. The sandwich beam is considered as a starting point for the load bearing structure and then it is modified with a cavity to embed avionics and thermal controls. The embedded avionics inside the load bearing structure would allow weight reduction of the aerospace vehicle due to elimination of separate electronics housing, interconnects, cables etc. The cavity reduces strength of the structure so various reinforcements methods are evaluated. The result of various reinforcements and their effectiveness are presented. The current generation of electronics produce massive amount of heat. In the case of embedded electronics, the excessive heat presents a major challenge to the structural and heat transfer engineers. The embedded nature of electronics prevents the use of the classical heat dissipative methods such as fans and high velocity air flows, etc. The integrated thermal control of the electronics has been designed using passive heat transfer device and highly optimized particulate composite thermal interface material (TIM). The TIMs are used to fill the air gaps and reduce contact resistance between two surfaces, such as electronics and heat dissipators. The efficiency of TIM directly affects the overall heat transfer ability of the integrated thermal control system. The effect of the particles at micron and nano scales are studied for the particulate composite TIM. The thermal boundary resistance study for the particulate composite TIM with nano silica particles is presented in this thesis. The FEA analysis is used to model thermal boundary resistance and compared with the theoretical micromechanics model. The heat pipes are

  14. Aerodynamics of flapping insect wing in inclined stroke plane hovering with ground effect

    NASA Astrophysics Data System (ADS)

    Gowda v, Krishne; Vengadesan, S.

    2014-11-01

    This work presents the time-varying aerodynamic forces and the unsteady flow structures of flapping insect wing in inclined stroke plane hovering with ground effect. Two-dimensional dragonfly model wing is chosen and the incompressible Navier-Stokes equations are solved numerically by using immersed boundary method. The main objective of the present work is to analyze the ground effect on the unsteady forces and vortical structures for the inclined stroke plane motions. We also investigate the influences of kinematics parameters such as Reynolds number (Re), stroke amplitude, wing rotational timing, for various distances between the airfoil and the ground. The effects of aforementioned parameters together with ground effect, on the stroke averaged force coefficients and regimes of force behavior are similar in both normal (horizontal) and inclined stroke plane motions. However, the evolution of the vortex structures which produces the effects are entirely different.

  15. Realizing in-plane surface diffraction by x-ray multiple-beam diffraction with large incidence angle

    SciTech Connect

    Huang, Xian-Rong Gog, Thomas; Assoufid, Lahsen; Peng, Ru-Wen; Siddons, D. P.

    2014-11-03

    Based on rigorous dynamical-theory calculations, we demonstrate the principle of an x-ray multiple-beam diffraction (MBD) scheme that overcomes the long-lasting difficulties of high-resolution in-plane diffraction from crystal surfaces. This scheme only utilizes symmetric reflection geometry with large incident angles but activates the out-of-plane and in-plane diffraction processes simultaneously and separately in the continuous MBD planes. The in-plane diffraction is realized by detoured MBD, where the intermediate diffracted waves propagate parallel to the surface, which corresponds to an absolute Bragg surface diffraction configuration that is extremely sensitive to surface structures. A series of MBD diffraction and imaging techniques may be developed from this principle to study surface/interface (misfit) strains, lateral nanostructures, and phase transitions of a wide range of (pseudo)cubic crystal structures, including ultrathin epitaxial films and multilayers, quantum dots, strain-engineered semiconductor or (multi)ferroic materials, etc.

  16. Ferroelectric control of in-plane to out-of-plane magnetization switching at poly(vinylidene fluoride)/iron interface

    NASA Astrophysics Data System (ADS)

    Wang, Rui-Qi; Zhu, Wan-Jiao; Ding, Hang-Chen; Gong, Shi-Jing; Duan, Chun-Gang

    2014-01-01

    Using relativistic density-functional theory calculations, we investigate magnetocrystalline anisotropy energy (MAE) of the poly(vinylidene fluoride)(PVDF)/Fe/Cu/Ag heterostructure. We find that MAE of this heterostructure can be flexibly manipulated by the ferroelectric polarization of PVDF. In particular, by carefully designing the interface structure, we demonstrate that the ferroelectric polarization reversal can switch the easy axis of the Fe layer from in-plane to out-of-plane, due to the surface/interface magnetoelectric effect. We expect such strategy would be beneficial to electric-field controlled magnetic data storage.

  17. Optical-based spectral modeling of infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, Salima; Lefebvre, Sidonie; Rommeluère, Sylvain; Ferrec, Yann; Primot, Jérôme

    2016-07-01

    We adopt an optical approach in order to model and predict the spectral signature of an infrared focal plane array. The modeling is based on a multilayer description of the structure and considers a one-dimensional propagation. It provides a better understanding of the physical phenomena occurring within the pixels, which is useful to perform radiometric measurements, as well as to reliably predict the spectral sensitivity of the detector. An exhaustive model is presented, covering the total spectral range of the pixel response. A heuristic model is also described, depicting a complementary approach that separates the different optical phenomena inside the pixel structure. Promising results are presented, validating the models through comparison with experimental results. Finally, advantages and limitations of this approach are discussed.

  18. Contextual phase estimation from two-plane intensity measurements.

    PubMed

    Deepak, V Joshua; Ivan, J Solomon

    2016-06-01

    In this work we construct examples of paraxial light fields whose intensities defined at all points in space do not have a corresponding cross-spectrally pure field amplitude reproducing the same set of transported intensities at all transverse planes. Nevertheless, two spatially separated transverse plane intensities as drawn from these examples are shown to have a corresponding cross-spectrally pure field amplitude, which, through paraxial free propagation between these two planes, reproduces the drawn transverse plane intensities. And the phase associated with such a field amplitude at a given transverse plane is found to be contextual, and intrinsically dependent on the pairing plane. PMID:27409450

  19. Analysis of a Griffith crack at the interface of two piezoelectric materials under anti-plane loading

    NASA Astrophysics Data System (ADS)

    Gherrous, M.; Ferdjani, H.

    2016-11-01

    The main objective of this work is the contribution to the study of the piezoelectric structures which contain preexisting defect (crack). For that, we consider a Griffith crack located at the interface of two piezoelectric materials in a semi-infinite plane structure. The structure is subjected to an anti-plane shearing combined with an in-plane electric displacement. Using integral Fourier transforms, the equations of piezoelectricity are converted analytically to a system of singular integral equations. The singular integral equations are further reduced to a system of algebraic equations and solved numerically by using Chebyshev polynomials. The stress intensity factor and the electric displacement intensity factor are calculated and used for the determination of the energy release rate which will be taken as fracture criterion. At the end, numerical results are presented for various parameters of the problem; they are also presented for an infinite plane structure.

  20. Preliminary Design and Analysis of an In-plane PRSEUS Joint

    NASA Technical Reports Server (NTRS)

    Lovejoy, Andrew E.; Poplawski, Steven

    2013-01-01

    As part of the National Aeronautics and Space Administration's (NASA's) Environmentally Responsible Aviation (ERA) program, the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) has been designed, developed and tested. However, PRSEUS development efforts to date have only addressed joints required to transfer bending moments between PRSEUS panels. Development of in-plane joints for the PRSEUS concept is necessary to facilitate in-plane transfer of load from PRSEUS panels to an adjacent structure, such as from a wing panel into a fuselage. This paper presents preliminary design and analysis of an in-plane PRSEUS joint for connecting PRSEUS panels at the termination of the rod-stiffened stringers. Design requirements are provided, the PRSEUS blade joint concept is presented, and preliminary design changes and analyses are carried out to examine the feasibility of the proposed in-plane PRSEUS blade joint. The study conducted herein focuses mainly on the PRSEUS structure on one side of the joint. In particular, the design requirements for the rod shear stress and bolt bearing stress are examined. A PRSEUS blade joint design was developed that demonstrates the feasibility of this in-plane PRSEUS joint concept to terminate the rod-stiffened stringers. The presented design only demonstrates feasibility, therefore, some areas of refinement are presented that would lead to a more optimum and realistic design.