Plane Strain Deformation in Generalized Thermoelastic Diffusion
NASA Astrophysics Data System (ADS)
Sharma, Nidhi; Kumar, Rajneesh; Ram, Paras
2008-08-01
The present investigation is concerned with plane strain deformation in homogeneous isotropic generalized thermoelastic diffusion subjected to a normal force, thermal source, and chemical potential source. Laplace and Fourier transform techniques are employed to solve the problem. The integral transform have been inverted by using a numerical technique to obtain the displacements, stresses, temperature distribution, and chemical potential distribution. The numerical results of these quantities are illustrated graphically to depict the response of various sources in the theories of thermoelastic diffusion and thermoelasticity for a particular model. Some particular cases have been deduced from the present investigation.
NASA Technical Reports Server (NTRS)
Buczek, M. B.; Gregory, M. A.; Herakovich, C. T.
1983-01-01
CLFE2D is a two dimensional generalized plane strain finite element code, using a linear, four node, general quadrilateral, isoparametric element. The program is developed to calculate the displacements, strains, stresses, and strain energy densities in a finite width composite laminate. CLFE2D offers any combination of the following load types: nodal displacements, nodal forces, uniform normal strain, or hygrothermal. The program allows the user to input one set of three dimensional orthotropic material properties. The user can then specify the angle of material principal orientation for each element in the mesh. Output includes displacements, stresses, strains and strain densities at points selected by the user. An option is also available to plot the underformed and deformed finite element meshes.
Constructing generalized Cesàro formulas for finite plane strains
NASA Astrophysics Data System (ADS)
Georgievskii, D. V.
2014-05-01
The problem of finding the displacement vector from a system of nonlinear differential equations which includes displacement gradient components is studied. Expressions on the right side of this system for certain parameter values have the kinematic sense of Lagrange and Euler finite strain tensors. The task is to construct generalized Cesàro formulas for finite strains. The construction of the solution consists of two stages (algebraic and differential), and the second is performed for space whose dimension is greater than or equal to two. An algorithm for the inversion of the original system is proposed, and analytical constructions for the case of two-dimensional space are performed. The problem is solved at the first (algebraic) stage, i.e., an exact analytical expression for the displacement vector components is derived through the known finite strain tensor and an unknown scalar function having the kinematic sense of rotation. Necessary conditions for the existence of this relationship are formulated.
Turbulent Plane Wakes Subjected to Successive Strains
NASA Technical Reports Server (NTRS)
Rogers, Michael M.
2003-01-01
Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases
Plane-strain tension tests on aluminum alloy sheet
Taha, F.; Hosford, W.; Graf, A.
1995-04-01
A simple way of making plane-strain tension tests on sheet specimens has been developed. This method was used to test sheets of aluminum alloy 2008 T4 and the results were analyzed in terms of a high exponent yield criterion and isotropic hardening. Experimentally measured forces agreed with those calculated from strain measurements using uniaxial tension test curves.
In-plane strain capability of cellulose EAPap material
NASA Astrophysics Data System (ADS)
Kim, Jaehwan; Jung, Woochul; Kang, Yukeun; Jang, Sang-Dong
2006-03-01
Electro-Active Paper (EAPap) has been interested in due to its merits in terms of lightweight, dry condition, large displacement output, low actuation voltage, low power consumption and biodegradability. EAPap actuator has been made with cellulose material. Cellulose fibers are dissolved into a solution and extruded in a sheet form, and thin gold electrodes are made on it. This out-of-plane bending deformation is useful for achieving flapping wings, micro-insect robots, and smart wall papers. On the other hand, in-plane strains, such as extension and contraction of EAPap materials are also promising for artificial muscle applications since the Young's modulus of EAPap materials is large. Therefore, we intended to investigate the in-plane strain of EAPap materials in the presence of electric fields. The EAPap samples preparation and the in-plane strain measurement are explained. The test results are shown in terms of electric field, frequency and the orientation of the samples. The power consumption and the strain energy of EAPap samples are discussed. Although there are still unknown facts in EAPap materials, this in-plane strain may be useful for artificial muscle applications.
Ultrafast vascular strain compounding using plane wave transmission.
Hansen, H H G; Saris, A E C M; Vaka, N R; Nillesen, M M; de Korte, C L
2014-03-03
Deformations of the atherosclerotic vascular wall induced by the pulsating blood can be estimated using ultrasound strain imaging. Because these deformations indirectly provide information on mechanical plaque composition, strain imaging is a promising technique for differentiating between stable and vulnerable atherosclerotic plaques. This paper first explains 1-D radial strain estimation as applied intravascularly in coronary arteries. Next, recent methods for noninvasive vascular strain estimation in a transverse imaging plane are discussed. Finally, a compounding technique that our group recently developed is explained. This technique combines motion estimates of subsequently acquired focused ultrasound images obtained at various insonification angles. However, because the artery moves and deforms during the multi-angle acquisition, errors are introduced when compounding. Recent advances in computational power have enabled plane wave ultrasound acquisition, which allows 100 times faster image acquisition and thus might resolve the motion artifacts. In this paper the performance of strain imaging using plane wave compounding is investigated using simulations of an artery with a vulnerable plaque and experimental data of a two-layered vessel phantom. The results show that plane wave compounding outperforms 0° focused strain imaging. For the simulations, the root mean squared error reduced by 66% and 50% for radial and circumferential strain, respectively. For the experiments, the elastographic signal-to-noise and contrast-to-noise ratio (SNR(e) and CNR(e)) increased with 2.1 dB and 3.7 dB radially, and 5.6 dB and 16.2dB circumferentially. Because of the high frame rate, the plane wave compounding technique can even be further optimized and extended to 3D in future.
Assumed strain formulation for the four-node quadrilateral with improved in-plane bending behaviour
NASA Astrophysics Data System (ADS)
Stolarski, Henryk K.; Chen, Yung-I.
1995-04-01
A new assumed strain quadrilateral element with highly accurate in-plane bending behavior is presented for plane stress and plane strain analysis. The basic idea of the formulation consists in identification of various modes of deformation and then in proper modification of the strain field in some of these modes. In particular, the strain operator corresponding to the in-plane bending modes is modified to simulate the strain field resulting from the assumptions usually made in structural mechanics. The modification of the strain field leads to the assumed strain operator on the element level. As a result, the so-called shear and membrane locking phenomena are alleviated. The element exhibits remarkable success in bending-dominated problems even when severely distorted and high aspect ratio meshes are used. Another advantage of the present assumed strain element is that locking for nearly incompressible materials is also mitigated. While this assumed strain element passes the patch test only for the parallelogram shapes, the element provides convergent solutions as long as the initially general form of the element approaches a parallelogram shape with the refinement of the mesh.
The plane strain tests in the PROMETRA program
NASA Astrophysics Data System (ADS)
Cazalis, B.; Desquines, J.; Carassou, S.; Le Jolu, T.; Bernaudat, C.
2016-04-01
A fuel cladding mechanical test, performed under conditions of plane strain deformation in the transverse direction of tube axis, was originally developed at Pennsylvania State University. It was decided to implement this original test within the PROMETRA program using the same experimental procedure and its optimization for a ring mechanical testing on plane strain conditions (PST tests) in hot cells laboratory. This paper presents a detailed description and an interpretation of the Plane Strain Tensile (PST) tests performed in the framework of the PROMETRA program on fresh and irradiated claddings. At first, the context of the PST tests is situated and the specificities of these tests implemented at CEA are justified. Indeed, a significant adjustment of the original experimental procedure is carried out in order to test the irradiated fuel cladding in the best possible conditions. Then, the tests results on fresh Zircaloy-4 and on irradiated Zircaloy-4, M5™ and ZIRLO® specimens are gathered. The main analyses in support of these tests, such as metallographies, fractographic examinations and finite element simulations are detailed. Finally, a synthesis of the interpretation of the tests is proposed. The PST test seems only representative of plane strain fracture conditions when the test material is very ductile (fresh or high temperature or low hydride material like M5TM). However, it provides a relevant representation of the RIA rupture initiation which is observed in irradiated cladding resulting from hydride rim damage due to the strong irradiation of a fuel rod.
Angle measures, general rotations, and roulettes in normed planes
NASA Astrophysics Data System (ADS)
Balestro, Vitor; Horváth, Ákos G.; Martini, Horst
2016-11-01
In this paper a special group of bijective maps of a normed plane (or, more generally, even of a plane with a suitable Jordan curve as unit circle) is introduced which we call the group of general rotations of that plane. It contains the isometry group as a subgroup. The concept of general rotations leads to the notion of flexible motions of the plane, and to the concept of Minkowskian roulettes. As a nice consequence of this new approach to motions the validity of strong analogues to the Euler-Savary equations for Minkowskian roulettes is proved.
The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding
Link, T.M.; Motta, A.T.; Koss, D.A.
1998-03-01
The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.
Cartamil-Bueno, S. J. E-mail: rbolivar@ugr.es; Rodríguez-Bolívar, S. E-mail: rbolivar@ugr.es
2015-06-28
The effects of tensile strain on the current-voltage (I-V) characteristics of hydrogenated-edge armchair graphene nanoribbons are investigated by using DFT theory. The strain is introduced in two different ways related to the two types of systems studied in this work: in-plane strained systems (A) and out-of-plane strained systems due to bending (B). These two kinds of strain lead to make a distinction among three cases: in-plane strained systems with strained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane homogeneously strained systems with unstrained, fixed electrodes (B). The systematic simulations to calculate the electronic transmission between two electrodes were focused on systems of 8 and 11 dimers in width. The results show that the differences between cases A2 and B are negligible, even though the strain mechanisms are different: in the plane case, the strain is uniaxial along its length; while in the bent case, the strain is caused by the arc deformation. Based on the study, a new type of nanoelectromechanical system solid state switching device is proposed.
A plane strain analysis of the blunted crack tip using small strain deformation plasticity theory
NASA Technical Reports Server (NTRS)
Mcgowan, J. J.; Smith, C. W.
1976-01-01
A deformation plasticity analysis of the tip region of a blunted crack in plane strain is presented. The power hardening material is incompressible both elastically and plastically, in order to simulate behavior of a stress freezing material above critical temperature. Stress and displacement fields surrounding the crack tip are presented. The results indicate that the maximum stress seen at the crack tip is indeed limited and is determined by the tensile properties; however, the scale over which the stresses act is dependent on the loading. Comparisons are good between the forward crack tip displacement and micro-fractographic measurments of stretch zones observed in plane strain fracture toughness tests.
Shear Band Formation in Plane Strain Experiments of Sand
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.; Sture, Stein
2000-01-01
A series of biaxial (plane strain) experiments were conducted on three sands under low (15 kPa) and high (100 kPa) confining pressure conditions to investigate the effects of specimen density, confining pressure, and sand grain size and shape on the constitutive and stability behavior of granular materials. The three sands used in the experiments were fine-, medium-, and coarse-grained uniform silica sands with rounded, subangular, and angular grains, respectively. Specimen deformation was readily monitored and analyzed with the help of a grid pattern imprinted on the latex membrane. The overall stress-strain behavior is strongly dependent on the specimen density, confining pressure, sand grain texture, and the resulting failure mode(s). That became evident in different degrees of softening responses at various axial strains. The relationship between the constitutive behavior and the specimens' modes of instability is presented. The failure in all specimens was characterized by two distinct and opposite shear bands. It was found that the measured dilatancy angles increase as the sand grains' angularities and sizes increase. The measured shear band inclination angles are also presented and compared with classical Coulomb and Roscoe solutions.
Shear Band Formation in Plane Strain Experiments of Sand
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.; Sture, Stein
2000-01-01
A series of biaxial (plane strain) experiments were conducted on three sands under low (15 kPa) and high (100 kPa) confining pressure conditions to investigate the effects of specimen density, confining pressure, and sand grain size and shape on the constitutive and stability behavior of granular materials. The three sands used in the experiments were fine-, medium-, and coarse-grained uniform silica sands with rounded, subangular, and angular grains, respectively. Specimen deformation was readily monitored and analyzed with the help of a grid pattern imprinted on the latex membrane. The overall stress-strain behavior is strongly dependent on the specimen density, confining pressure, sand grain texture, and the resulting failure mode(s). That became evident in different degrees of softening responses at various axial strains. The relationship between the constitutive behavior and the specimens' modes of instability is presented. The failure in all specimens was characterized by two distinct and opposite shear bands. It was found that the measured dilatancy angles increase as the sand grains' angularities and sizes increase. The measured shear band inclination angles are also presented and compared with classical Coulomb and Roscoe solutions.
General image method in a plane-layered elastostatic medium
NASA Technical Reports Server (NTRS)
Fares, N.; Li, V. C.
1988-01-01
The general-image method presently used to obtain the elastostatic fields in plane-layered media relies on the use of potentials in order to represent elastic fields. For the case of a single interface, this method yields the displacement field in closed form, and is applicable to antiplane, plane, and three-dimensional problems. In the case of multiplane interfaces, the image method generates the displacement fields in terms of infinite series whose convergences can be accelerated to improve method efficiency.
NASA Astrophysics Data System (ADS)
Hiraoka, Naoki; Matsuzaki, Ryosuke; Todoroki, Akira
In order to improve performance of anti lock brake system (ABS) and detect condition of road surface, intelligent tires that monitor strain of interior surface and rolling radius of tire are demanded. However, the high stiffness of an attached sensor like a strain gauge causes debonding of sensors from tire rubber. In the present study, noncontact concurrent monitoring method is proposed using digital image correlation method (DICM) and spotlight projection. In-plane strain and out-of-plane displacement (rolling radius) are calculated by using image processing with an image of interior surface of tire that is taken with a single CCD camera fixed on wheel rim. New monitoring system is applied to Al beam and commercially available radial tire. As a result, this monitoring system is proved to be able to measure in-plane strain and out-of-plane displacement with high accuracy, and confirmed to be effective for concurrent monitoring of tires.
Strained layer superlattice focal plane array having a planar structure
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.
Generalized dual-plane digital holographic imaging method
NASA Astrophysics Data System (ADS)
Wang, Fengpeng; Wang, Dayong; Panezai, Spozmai; Rong, Lu; Wang, Yunxin; Zhao, Jie
2016-12-01
A generalized dual-plane technique for digital holographic imaging is proposed. Two holograms are recorded at two slightly displaced planes. The complex amplitude of the plane reference wave is obtained according to the measured intensity of the reference beam and the spectrum of hologram. The holograms are modified with the known information of the reference wave. Then, the modified holograms are reconstructed by the dual-plane algorithm. The zero-order and the twin images are removed in the reconstructed image. The simulation and experiments demonstrate that this method is valid for both on-axis and off-axis digital holography and high resolution reconstruction is achieved even with a very small offset angle of the reference beam.
The plane strain shear fracture of the advanced high strength steels
NASA Astrophysics Data System (ADS)
Sun, Li
2013-12-01
The "shear fracture" which occurs at the high-curvature die radii in the sheet metal forming has been reported to remarkably limit the application of the advanced high strength steels (AHSS) in the automobile industry. However, this unusual fracture behavior generally cannot be predicted by the traditional forming limit diagram (FLD). In this research, a new experimental system was developed in order to simulate the shear fracture, especially at the plane strain state which is the most common state in the auto-industry and difficult to achieve in the lab due to sample size. Furthermore, the system has the capability to operate in a strain rate range from quasi-static state to the industrial forming state. One kinds of AHSS, Quenching-Partitioning (QP) steels have been performed in this test and the results show that the limiting fracture strain is related to the bending ratio and strain rate. The experimental data support that deformation-induced heating is an important cause of "shear fracture" phenomena for AHSS: a deformation-induced quasi-heating caused by smaller bending ratio and high strain rate produce a smaller limiting plane strain and lead a "shear fracture" in the component.
The plane strain shear fracture of the advanced high strength steels
Sun, Li
2013-12-16
The “shear fracture” which occurs at the high-curvature die radii in the sheet metal forming has been reported to remarkably limit the application of the advanced high strength steels (AHSS) in the automobile industry. However, this unusual fracture behavior generally cannot be predicted by the traditional forming limit diagram (FLD). In this research, a new experimental system was developed in order to simulate the shear fracture, especially at the plane strain state which is the most common state in the auto-industry and difficult to achieve in the lab due to sample size. Furthermore, the system has the capability to operate in a strain rate range from quasi-static state to the industrial forming state. One kinds of AHSS, Quenching-Partitioning (QP) steels have been performed in this test and the results show that the limiting fracture strain is related to the bending ratio and strain rate. The experimental data support that deformation-induced heating is an important cause of “shear fracture” phenomena for AHSS: a deformation-induced quasi-heating caused by smaller bending ratio and high strain rate produce a smaller limiting plane strain and lead a “shear fracture” in the component.
Characterization of network parameters for UHMWPE by plane strain compression.
Abreu, E L; Ngo, H D; Bellare, A
2014-04-01
Ultra-high molecular weight polyethylene (PE) is used as a bearing material for total joint replacement prostheses since it is a tough, wear-resistant semicrystalline polymer. Despite its high resistance to wear, PE components have shown measureable wear in vivo, which can cause wear-particle induced osteolysis. Crosslinking of PE using ionizing radiation has been shown to increase wear resistance since both chemical crosslinks and physical entanglements provide high resistance to wear. Molecular characterization of crosslinked PEs is usually conducted using equilibrium swelling or by quantifying gel content. In this study, we compared crosslink densities and molecular weight between crosslinks derived from equilibrium swelling to those obtained by applying the Gaussian and Eight-Chain model to describe plane strain compression of the PE melt. The latter approach has the advantage of accounting for contributions of entanglements to the overall crosslink density, which solvent-based techniques largely neglect. As expected, the crosslink density calculated from model fitting increased monotonically with increase in radiation dose in a 0-200kGy dose range, with a corresponding monotonic decrease in molecular weight between crosslinks, but provided higher values of crosslink density and correspondingly lower values of molecular weight between crosslinks compared to the equilibrium swelling technique.
Langford, G.
1980-05-01
The strain hardening of iron at high strains in plane strain elongation (strip drawing) is shown to fall increasingly below that of drawn iron wires at true strains above 2, going through zero strain hardening at epsilon = 3.0, and becoming strongly negative thereafter, at least up to epsilon = 4.1. High resolution selected area electron diffraction has been used to map the size, shape and crystallographic orientations of a group of about 50 contiguous cells centered around an incipient shear band in an edge section of a strip drawn to epsilon = 1.8. This map shows no textural instability or change in orientation associated with the shear band, although it does show substantial misorientations throughout the group of cells, the axis of these misorientations lying in the same direction as the trace of the shear band. No other large misorientations (i.e. 5/sup 0/ or so) are present. The only instability seen in this shear band is microstructural: the slip distances in the two primary slip directions are quite anisotropic, being much longer along the trace of the shear band. Note that this shear band has appeared during the linear hardening portion of the high-strain hardening curve of the drawn strip. It is therefore considered a direct weakening mechanism rather than a result of another weakening effect. Further such orientation maps have been or are being prepared for more highly deformed strip, and for wire and pure-shear specimens as well.
Lattice strains and polarized luminescence in homoepitaxial growth of a-plane ZnO
NASA Astrophysics Data System (ADS)
Matsui, Hiroaki; Tabata, Hitoshi
2012-12-01
In-plane lattice strains in a-plane zinc oxide (ZnO) homoepitaxial layers were selectively introduced by changing substrate type and growth conditions. Strain-free layers were observed when using a Crystec ZnO substrate, which resulted in atomically flat surfaces with nano-facets consisting of the m-plane (10-10) at atomic scale. In contrast, ZnO layers on Goodwill ZnO substrates possessed in-plane lattice strains due to generation of basal-plane stacking faults. The degree of lattice strains was systematically changed by the oxygen pressure, which clarified the close correlation between photoluminescence (PL) polarization and lattice strains. The polarization ratio of PL enhanced with the lattice strains.
A numerical method for determining the strain rate intensity factor under plane strain conditions
NASA Astrophysics Data System (ADS)
Alexandrov, S.; Kuo, C.-Y.; Jeng, Y.-R.
2016-07-01
Using the classical model of rigid perfectly plastic solids, the strain rate intensity factor has been previously introduced as the coefficient of the leading singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. Since then, many strain rate intensity factors have been determined by means of analytical and semi-analytical solutions. However, no attempt has been made to develop a numerical method for calculating the strain rate intensity factor. This paper presents such a method for planar flow. The method is based on the theory of characteristics. First, the strain rate intensity factor is derived in characteristic coordinates. Then, a standard numerical slip-line technique is supplemented with a procedure to calculate the strain rate intensity factor. The distribution of the strain rate intensity factor along the friction surface in compression of a layer between two parallel plates is determined. A high accuracy of this numerical solution for the strain rate intensity factor is confirmed by comparison with an analytic solution. It is shown that the distribution of the strain rate intensity factor is in general discontinuous.
Plane stress-strain state of a circular cylindrical bushing due to a finite out-of-plane shear
NASA Astrophysics Data System (ADS)
Zhukov, B. A.
2017-01-01
The paper deals with the determination of the stress-strain state due to a finite longitudinal shear in a circular cylindrical bushing manufactured from the Mooney-Rivlin material. Some expressions for the internal stresses and displacements in the plane perpendicular to the longitudinal shear are obtained.
Comparison of experiment and theory for elastic-plastic plane strain crack growth
Hermann, L; Rice, J R
1980-02-01
Recent theoretical results on elastic-plastic plane strain crack growth, and experimental results for crack growth in a 4140 steel in terms of the theoretical concepts are reviewed. The theory is based on a recent asymptotic analysis of crack surface opening and strain distributions at a quasi-statically advancing crack tip in an ideally-plastic solid. The analysis is incomplete in that some of the parameters which appear in it are known only approximately, especially at large scale yielding. Nevertheless, it suffices to derive a relation between the imposed loading and amount of crack growth, prior to general yielding, based on the assumption that a geometrically similar near-tip crack profile is maintained during growth. The resulting predictions for the variation of J with crack growth are found to fit well to the experimental results obtained on deeply cracked compact specimens.
Evaluation of Instability Phenomena in Sands: Plane Strain Versus Triaxial Conditions
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.
2001-01-01
Extensive research was carried out in the 1950s on theories of plasticity to extend the concepts developed for metals to materials that failed according to the Mohr-Coulomb criterion. The new ideas made it possible to merge the two distinct concepts (strength and deformation techniques) into one that relies on better understanding of plasticity and resulted in a rapid growth in the field of constitutive modeling of soil behavior. At the same time advanced experimental apparatuses and laboratory procedures were developed to calibrate the models. However, most laboratory experiments on granular materials are performed under Conventional Triaxial Conditions (CTC) for the purposes of evaluating constitutive behavior and stability properties, whereas most geotechnical field problems are closer to the Plane Strain (PS) condition. The triaxial tests performed in most laboratories comprise a simplification over in situ states and allow easier and robust experimentation. Most landslide problems, failure of soils beneath shallow and deep foundations, and failure of retaining structures, are cases that can generally be considered as plane strain. Strength and deformation characteristics of granular materials loaded in plane strain may be considerably different from those observed in CTC. Most studies on sands were limited to evaluating the constitutive behavior and in some cases extended to briefly describing the associated instability phenomena. This paper presents the results of a series of PS and CTC experiments performed on fine uniform silica sand known as F-75 Ottawa sand. Advanced analysis techniques were used to study the instability phenomena, which yielded very accurate measurements of shear bands occurrences and patterns. Destructive thin-sectioning technique along with monitoring the specimen surface deformation was used in the PS experiments and Computed Tomography (CT) was used to investigate the progress of primary and secondary shear bands in specimens
Dispersion of circumferential waves in cylindrically anisotropic layered pipes in plane strain.
Vasudeva, R Y; Sudheer, G; Vema, Anu Radha
2008-06-01
Dispersion spectra of circumferential waves along the periphery of circular pipes made of layered anisotropic materials do not seem to be available in literature. This note attempts to partially fill this gap by providing the dispersion spectra in two and three layered cylindrically anisotropic pipes in plane strain motion. The spectra for pipes executing time harmonic vibrations in plane strain condition are obtained as roots of a numerical characteristic equation derived extending a weighted residual method of solution of the governing equations for a single layer pipe [Towfighi et al., J. Appl. Mech. 69, 283-291 (2002)] to a general N layered pipe. The anisotropic elastic coefficients are considered to be independent of position coordinates and the bond condition at interfaces of the layers is assumed to be perfect. Numerical illustrations are presented for two and three layered pipes with anisotropy directions differing in adjacent layers. Increase in curvature of the pipe and inclination of the fiber orientation in the outermost layers to propagation direction are factors that seem to influence the mode number and pattern within the limited examples worked out.
Texture development and hardening characteristics of steel sheets under plane-strain compression
Friedman, P.A.; Liao, K.C.; Pan, J.; Barlat, F.
1999-04-01
Crystallographic texture development and hardening characteristics of a hot-rolled, low-carbon steel sheet due to cold rolling were investigated by idealizing the cold rolling process as plane-strain compression. The starting anisotropy of the test material was characterized by examination of the grain structure by optical microscopy and the preferred crystal orientation distribution by x-ray diffraction. Various heat treatments were used in an effort to remove the initial deformation texture resulting from hot rolling. The plastic anisotropy of the starting material was investigated with tensile tests on samples with the tensile axis parallel, 45{degree}, and perpendicular to the rolling direction. The grain structure after plane-strain compression was studied by optical microscopy, and the new deformation texture was characterized by x-ray diffraction pole figures. These figures are compared with the theoretical pole figures produced from a Taylor-like polycrystal model based on a pencil-glide slip system. The uniaxial tensile stress-strain curve and the plane-strain, compressive stress-strain curve of the sheet were used to calibrate the material parameters in the model. The experimental pole figures were consistent with the findings in the theoretical study. The experimental and theoretical results suggest that the initial texture due to hot rolling was insignificant as compared with the texture induced by large strains under plane-strain compression.
A semi-implicit finite strain shell algorithm using in-plane strains based on least-squares
NASA Astrophysics Data System (ADS)
Areias, P.; Rabczuk, T.; de Sá, J. César; Natal Jorge, R.
2015-04-01
The use of a semi-implicit algorithm at the constitutive level allows a robust and concise implementation of low-order effective shell elements. We perform a semi-implicit integration in the stress update algorithm for finite strain plasticity: rotation terms (highly nonlinear trigonometric functions) are integrated explicitly and correspond to a change in the (in this case evolving) reference configuration and relative Green-Lagrange strains (quadratic) are used to account for change in the equilibrium configuration implicitly. We parametrize both reference and equilibrium configurations, in contrast with the so-called objective stress integration algorithms which use a common configuration. A finite strain quadrilateral element with least-squares assumed in-plane shear strains (in curvilinear coordinates) and classical transverse shear assumed strains is introduced. It is an alternative to enhanced-assumed-strain (EAS) formulations and, contrary to this, produces an element satisfying ab-initio the Patch test. No additional degrees-of-freedom are present, contrasting with EAS. Least-squares fit allows the derivation of invariant finite strain elements which are both in-plane and out-of-plane shear-locking free and amenable to standardization in commercial codes. Two thickness parameters per node are adopted to reproduce the Poisson effect in bending. Metric components are fully deduced and exact linearization of the shell element is performed. Both isotropic and anisotropic behavior is presented in elasto-plastic and hyperelastic examples.
Skigin, Diana C; Depine, Ricardo A
2008-05-01
We show that the problem of scattering of an obliquely incident plane wave by a general-shaped groove engraved on a perfectly conducting plane, which was recently studied by Basha et al. [J. Opt. Soc. Am. A24, 1647 (2007)], was solved 11 years ago using the same formulation. This method was further extended to deal with a finite number of grooves and also with complex apertures including several nonlossy and lossy dielectrics, as well as real metals.
Tunable biaxial in-plane compressive strain in a Si nanomembrane transferred on a polyimide film
Kim, Munho; Mi, Hongyi; Cho, Minkyu; Seo, Jung-Hun; Ma, Zhenqiang; Zhou, Weidong; Gong, Shaoqin
2015-05-25
A method of creating tunable and programmable biaxial compressive strain in silicon nanomembranes (Si NMs) transferred onto a Kapton{sup ®} HN polyimide film has been demonstrated. The programmable biaxial compressive strain (up to 0.54%) was generated utilizing a unique thermal property exhibited by the Kapton HN film, namely, it shrinks from its original size when exposed to elevated temperatures. The correlation between the strain and the annealing temperature was carefully investigated using Raman spectroscopy and high resolution X-ray diffraction. It was found that various amounts of compressive strains can be obtained by controlling the thermal annealing temperatures. In addition, a numerical model was used to evaluate the strain distribution in the Si NM. This technique provides a viable approach to forming in-plane compressive strain in NMs and offers a practical platform for further studies in strain engineering.
Plane-strain crack problems in microstructured solids governed by dipolar gradient elasticity
NASA Astrophysics Data System (ADS)
Gourgiotis, P. A.; Georgiadis, H. G.
2009-11-01
The present study aims at determining the elastic stress and displacement fields around the tips of a finite-length crack in a microstructured solid under remotely applied plane-strain loading (mode I and II cases). The material microstructure is modeled through the Toupin-Mindlin generalized continuum theory of dipolar gradient elasticity. According to this theory, the strain-energy density assumes the form of a positive-definite function of the strain tensor (as in classical elasticity) and the gradient of the strain tensor (additional term). A simple but yet rigorous version of the theory is employed here by considering an isotropic linear expression of the elastic strain-energy density that involves only three material constants (the two Lamé constants and the so-called gradient coefficient). First, a near-tip asymptotic solution is obtained by the Knein-Williams technique. Then, we attack the complete boundary value problem in an effort to obtain a full-field solution. Hypersingular integral equations with a cubic singularity are formulated with the aid of the Fourier transform. These equations are solved by analytical considerations on Hadamard finite-part integrals and a numerical treatment. The results show significant departure from the predictions of standard fracture mechanics. In view of these results, it seems that the classical theory of elasticity is inadequate to analyze crack problems in microstructured materials. Indeed, the present results indicate that the stress distribution ahead of the crack tip exhibits a local maximum that is bounded. Therefore, this maximum value may serve as a measure of the critical stress level at which further advancement of the crack may occur. Also, in the vicinity of the crack tip, the crack-face displacement closes more smoothly as compared to the standard result and the strain field is bounded. Finally, the J-integral (energy release rate) in gradient elasticity was evaluated. A decrease of its value is noticed
Stretch bending - the plane within the sheet where strains reach the forming limit curve
NASA Astrophysics Data System (ADS)
Neuhauser, F. M.; Terrazas, O. R.; Manopulo, N.; Hora, P.; Van Tyne, C. J.
2016-11-01
Finite element analysis (FEA) was used to model the angular stretch bend test, where a strip of sheet metal is locked at both ends and a tool with a radius stretches and bends the center of the strip until failure. The FEA program used in the study was Abaqus. The FEA model was verified by experimental work using a dual phase steel (DP600) and with a simplified analytical analysis. The FEA model was used to simulate the experimental test for various frictional conditions and various radii of an upward moving tool. The primary objective of the study was to evaluate the concave-side rule, which states that during stretch bending the forming limit occurs when the strains on the concave surface plane of the bent sheet (i.e. bottom plane) reach the forming limit curve (FLC). The verification with experimental data indicates that the FEA model represents the process very well. Only conditions where failure occurred on or near the tooling are included in the results. The FEA simulations showed that the actual forming limit of the sheet occurs when the strains on the bottom plane of the sheet (i.e. concave side of the bend) reach the forming limit curve for high friction and small tool radii. For lower friction and for larger tool radii the actual forming limit occurs when strains on other planes in the sheet (i.e. mid planes or top surface plane) reach the forming limit curve. The implications of these results suggest that care must be taken in assessing forming operations when both stretch and bending occur. Although it is known that the FLC cannot predict the forming limit for small bend radii, the common assumption that the forming limit occurs when the strains for the middle thickness plane of the sheet reach the forming limit curve or that the concave side rule is often made. Understanding the limits of this assumption needs to be carefully and critically evaluated.
Reversed polarized emission in highly strained a -plane GaN/AlN multiple quantum wells
NASA Astrophysics Data System (ADS)
Mata, R.; Cros, A.; Budagosky, J. A.; Molina-Sánchez, A.; Garro, N.; García-Cristóbal, A.; Renard, J.; Founta, S.; Gayral, B.; Bellet-Amalric, E.; Bougerol, C.; Daudin, B.
2010-09-01
The polarization of the emission from a set of highly strained a -plane GaN/AlN multiple quantum wells of varying well widths has been studied. A single photoluminescence peak is observed that shifts to higher energies as the quantum well thickness decreases due to quantum confinement. The emitted light is linearly polarized. For the thinnest samples the preferential polarization direction is perpendicular to the wurtzite c axis with a degree of polarization that decreases with increasing well width. However, for the thickest well the preferred polarization direction is parallel to the c axis. Raman scattering, x-ray diffraction, and transmission electron microscopy studies have been performed to determine the three components of the strain tensor in the active region. Moreover, the experimental results have been compared with the strain values computed by means of a model based on the elastic continuum theory. A high anisotropic compressive in-plane strain has been found, namely, -0.6% and -2.8% along the in-plane directions [11¯00] and [0001], respectively, for the thickest quantum well. The oscillator strength of the lowest optical transition has been calculated within the framework of a multiband envelope function model for various quantum well widths and strain values. The influence of confinement and strain on the degree of polarization is discussed and compared with experiment considering various sets of material parameters.
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.
The Unloading Modulus of Akdq Steel after Uniaxial and Near Plane-Strain Plastic Deformation
NASA Astrophysics Data System (ADS)
Pavlina, E. J.; Levy, B. S.; van Tyne, C. J.; Kwon, S. O.; Moon, Y. H.
Springback is a problem in the manufacture of a variety of automotive components. To determine springback, it is necessary to know the strength of the material after plastic deformation and the slope of the unloading curve (i.e. the unloading modulus). Prior investigations have shown that the unloading modulus for steels after plastic deformation has a slope that is lower than the normally accepted value for Young's modulus. Previous studies on the slope of the unloading curve were after uniaxial tensile plastic deformation. In the present study, the unloading modulus for an aluminum killed drawing quality (AKDQ) steel was evaluated after both uniaxial and near plane strain deformation. A tube hydroforming system was used for near plane-strain deformation. The average unloading modulus following uniaxial deformation for the AKDQ steel is approximately 168 GPa. The average unloading modulus for the circumferential stress component after near plane-strain deformation is lower than after uniaxial deformation. For a given amount of overall plastic deformation, the axial component of the unloading modulus is greater than the circumferential component, and with increased plastic strain, the unloading modulus for both components decreases. These results demonstrate that the components of the unloading modulus are dependent on the strain path of the prior plastic deformation.
Experimental and Analytical Investigations on Plane Strain Toughness for 7085 Aluminum Alloy
NASA Astrophysics Data System (ADS)
Shuey, R. T.; Barlat, F.; Karabin, M. E.; Chakrabarti, D. J.
2009-02-01
Data are presented on plane strain fracture toughness, yield strength, and strain hardening for three orientations of samples from quarter-thickness ( t/4) and midthickness ( t/2) locations of alloy 7085 plates with different gages aged past peak strength with different 2nd step aging times (T7X). These data are fit to an expression adapted from Hahn and Rosenfield (1968), in which toughness is proportional to strain hardening, the square root of yield strength, and the square root of a critical strain ɛ c . Strain-hardening exponent n is replaced by an alternative measure, since the stress-strain data do not follow a power law. With increased overaging, the increase of strain hardening dominates the decrease of strength, such that toughness increases. The critical strain, which represents the influence of the microstructure on toughness, has no trend with overaging time. Constituents and grain boundary precipitates, thought to be the microstructural elements most differentiating alloy 7085 from alloy 7050, are quantified at t/4 and at t/2 on one plate. From this the greater critical strain at t/2 than at t/4 is mainly attributed to greater effective spacing of constituents. Critical strain is also greater with longitudinal loading and crack propagating in the long transverse direction, but definite understanding of this will require better anisotropic fracture mechanics and further microstructural characterization.
Shimada, T; Okuno, J; Ishii, Y; Kitamura, T
2012-03-07
We investigated a nanometer-sharp magnetic domain wall (DW) structure in a free-standing Fe(110) monolayer and studied the crucial role of in-plane strain using fully unconstrained noncollinear ab initio spin-density-functional theory calculations within the generalized gradient approximation. The DW width is calculated to be 0.86 nm. A precise vector-field description of the magnetization density revealed that a noncollinear character in the DW was spatially confined between atoms, whereas a collinear and high magnetization density was localized around each atom. In the rapid rotation of magnetic moments in the DW, we found an electron rearrangement from the d(zx) and d(x(2)-y(2)) states to the d(xy), d(yz) and d(z(2)) states due to a shift of band structures. Applied tensile and compressive in-plane strains both bring about narrower DWs in the monolayer except when the strain is small. The strain dependence of the DW width is discussed in terms of both exchange interaction and magnetocrystalline anisotropy.
The unique effect of in-plane anisotropic strain in the magnetization control by electric field
NASA Astrophysics Data System (ADS)
Zhao, Y. Y.; Wang, J.; Hu, F. X.; Liu, Y.; Kuang, H.; Wu, R. R.; Sun, J. R.; Shen, B. G.
2016-05-01
The electric field control of magnetization in both (100)- and (011)-Pr0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PSMO/PMN-PT) heterostructures were investigated. It was found that the in-plane isotropic strain induced by electric field only slightly reduces the magnetization at low temperature in (100)-PSMO/PMN-PT film. On the other hand, for (011)-PSMO/PMN-PT film, the in-plane anisotropic strain results in in-plane anisotropic, nonvolatile change of magnetization at low-temperature. The magnetization, remanence and coercivity along in-plane [100] direction are suppressed by the electric field while the ones along [01-1] direction are enhanced, which is ascribed to the extra effective magnetic anisotropy induced by the electric field via anisotropic piezostrains. More interestingly, such anisotropic modulation behaviors are nonvolatile, demonstrating a memory effect.
Finite Element Modeling of Plane Strain Toughness for 7085 Aluminum Alloy
NASA Astrophysics Data System (ADS)
Karabin, M. E.; Barlat, F.; Shuey, R. T.
2009-02-01
In this work, the constitutive model for 7085-T7X (overaged) aluminum alloy plate samples with controlled microstructures was developed. Different lengths of 2nd step aging times produced samples with similar microstructure but different stress-strain curves ( i.e., different nanostructure). A conventional phenomenological strain-hardening law with no strain gradient effects was proposed to capture the peculiar hardening behavior of the material samples investigated in this work. The classical Gurson-Tvergaard potential, which includes the influence of void volume fraction (VVF) on the plastic flow behavior, as well as an extension proposed by Leblond et al.,[3] were considered. Unlike the former, the latter is able to account for the influence of strain hardening on the VVF growth. All the constitutive coefficients used in this work were based on experimental stress-strain curves obtained in uniaxial tension and on micromechanical modeling results of a void embedded in a matrix. These material models were used in finite element (FE) simulations of a compact tension (CT) specimen. An engineering criterion based on the instability of plastic flow at a crack tip was used for the determination of plane strain toughness K Ic . The influence of the microstructure was lumped into a single state variable, the initial void volume fraction. The simulation results showed that the strain-hardening behavior has a significant influence on K Ic .
NASA Astrophysics Data System (ADS)
Graba, M.
2016-12-01
This paper presents a numerical analysis of the relationship between in-plane constraints and the crack tip opening displacement (CTOD) for single-edge notched bend (SEN(B)) specimens under predominantly plane strain conditions. It provides details of the numerical model and discusses the influence of external load and in-plane constraints on the CTOD. The work also reviews methods for determining the CTOD. The new formula proposed in this paper can be used to estimate the value of the coefficient dn as a function of the relative crack length, the strain hardening exponent and the yield strength - dn(n, σ0/E, a/W), with these parameters affecting the level of in-plane constraints. Some of the numerical results were approximated using simple mathematical formulae.
Real-time measurement system for in-plane displacement and strain based on vision
NASA Astrophysics Data System (ADS)
Luo, Tao; Jin, Yi; Zhu, Ye; Zhai, Chao
2013-08-01
In this paper, combining optical measurement with conventional material testing machine, a real-time in-plane displacement and strain measurement system is built, which is applied to the material testing machine. This system can realize displacement and strain measurement of a large deformation sample moreover it can observe the sample crack on line. The change of displacement field is obtained through the change of center coordinate of each point of a grid lattice in the surface of the testing sample, according to two-dimensional sort coding for the grid in the traditional automated grid method, in this paper, an improved one-dimensional code method is adopted which make calculating speed much faster and the algorithm more adaptable. The measurement of the stability and precision of this system are made using the calibration board whose position precision is about 1.5 micron. The results show that the short-time stability of this system is about 0.5micron. At last, this system is used for strain measurement in a sample tension test, and the result shows that the system can acquire in-plane displacement and strain measurement results accurately and real-time, the velocity of image processing can reach 10 frame per second; or it can observe sample crack on line and storage the test process, the max velocity of observation and storage is 100 frame per second.
Reconstruction of in-plane strain maps using hybrid dense sensor network composed of sensing skin
NASA Astrophysics Data System (ADS)
Downey, Austin; Laflamme, Simon; Ubertini, Filippo
2016-12-01
The authors have recently developed a soft-elastomeric capacitive (SEC)-based thin film sensor for monitoring strain on mesosurfaces. Arranged in a network configuration, the sensing system is analogous to a biological skin, where local strain can be monitored over a global area. Under plane stress conditions, the sensor output contains the additive measurement of the two principal strain components over the monitored surface. In applications where the evaluation of strain maps is useful, in structural health monitoring for instance, such signal must be decomposed into linear strain components along orthogonal directions. Previous work has led to an algorithm that enabled such decomposition by leveraging a dense sensor network configuration with the addition of assumed boundary conditions. Here, we significantly improve the algorithm’s accuracy by leveraging mature off-the-shelf solutions to create a hybrid dense sensor network (HDSN) to improve on the boundary condition assumptions. The system’s boundary conditions are enforced using unidirectional RSGs and assumed virtual sensors. Results from an extensive experimental investigation demonstrate the good performance of the proposed algorithm and its robustness with respect to sensors’ layout. Overall, the proposed algorithm is seen to effectively leverage the advantages of a hybrid dense network for application of the thin film sensor to reconstruct surface strain fields over large surfaces.
Effect of sagittal plane mechanics on ACL strain during jump landing.
Bakker, Ryan; Tomescu, Sebastian; Brenneman, Elora; Hangalur, Gajendra; Laing, Andrew; Chandrashekar, Naveen
2016-09-01
The relationships between non-contact anterior cruciate ligament injuries and the underlying biomechanics are still unclear, despite large quantities of academic research. The purpose of this research was to study anterior cruciate ligament strain during jump landing by investigating its correlation with sagittal plane kinetic/kinematic parameters and by creating an empirical model to estimate the maximum strain. Whole-body kinematics and ground reaction forces were measured from seven subjects performing single leg jump landing and were used to drive a musculoskeletal model that estimated lower limb muscle forces. These muscle forces and kinematics were then applied on five instrumented cadaver knees using a dynamic knee simulator system. Correlation analysis revealed that higher ground reaction force, lower hip flexion angle and higher hip extension moment among others were correlated with higher peak strain (p < 0.05). Multivariate regression analyses revealed that intrinsic anatomic factors account for most of the variance in strain. Among the extrinsic variables, hip and trunk flexion angles significantly contributed to the strain. The empirical relationship developed in this study could be used to predict the relative strain between jumps of a participant and may be beneficial in developing training programs designed to reduce an athlete's risk of injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1636-1644, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
Analysis of plane-plastic stress problems with axial symmetry in strain-hardening range
NASA Technical Reports Server (NTRS)
Wu, M H Lee
1951-01-01
A simple method is developed for solving plane-plastic-stress problems with axial symmetry in the strain-hardening range which is based on the deformation theory of plasticity employing the finite-strain concept. The equations defining the problems are first reduced to two simultaneous nonlinear differential equations involving two dependent variables: (a) the octahedral shear strain, and (b) a parameter indicating the ratio of principal stresses. By multiplying the load and dividing the radius by an arbitrary constant, it is possible to solve these problems without iteration for any value of the modified load. The constant is determined by the boundary condition. This method is applied to a circular membrane under pressure, a rotating disk without and with a central hole, and an infinite plate with a circular hole. Two materials, inconel x and 16-25-6, the octahedral shear stress-strain relations of which do not follow the power law, are used. Distributions of octahedral shear strain, as well as of principal stresses and strains, are obtained. These results are compared with the results of the same problems in the elastic range.
Band gap modulation of transition-metal dichalcogenide MX2 nanosheets by in-plane strain
NASA Astrophysics Data System (ADS)
Su, Xiangying; Ju, Weiwei; Zhang, Ruizhi; Guo, Chongfeng; Yong, Yongliang; Cui, Hongling; Li, Xiaohong
2016-10-01
The electronic properties of quasi-two-dimensional honeycomb structures of MX2 nanosheets (M=Mo, W and X=S, Se) subjected to in-plane biaxial strain have been investigated using first-principles calculations. We demonstrate that the band gap of MX2 nanosheets can be widely tuned by applying tensile or compressive strain, and these ultrathin materials undergo a universal reversible semiconductor-metal transition at a critical strain. Compared to WX2, MoX2 need a smaller critical tensile strain for the band gap close, and MSe2 need a smaller critical compressive strain than MS2. Taking bilayer MoS2 as an example, the variation of the band structures was studied and the semiconductor-metal transition involves a slightly different physical mechanism between tensile and compressive strain. The ability to tune the band gap of MX2 nanosheets in a controlled fashion over a wide range of energy opens up the possibility for its usage in a range of application.
In-plane displacement and strain measurements using a camera phone and digital image correlation
NASA Astrophysics Data System (ADS)
Yu, Liping; Pan, Bing
2014-05-01
In-plane displacement and strain measurements of planar objects by processing the digital images captured by a camera phone using digital image correlation (DIC) are performed in this paper. As a convenient communication tool for everyday use, the principal advantages of a camera phone are its low cost, easy accessibility, and compactness. However, when used as a two-dimensional DIC system for mechanical metrology, the assumed imaging model of a camera phone may be slightly altered during the measurement process due to camera misalignment, imperfect loading, sample deformation, and temperature variations of the camera phone, which can produce appreciable errors in the measured displacements. In order to obtain accurate DIC measurements using a camera phone, the virtual displacements caused by these issues are first identified using an unstrained compensating specimen and then corrected by means of a parametric model. The proposed technique is first verified using in-plane translation and out-of-plane translation tests. Then, it is validated through a determination of the tensile strains and elastic properties of an aluminum specimen. Results of the present study show that accurate DIC measurements can be conducted using a common camera phone provided that an adequate correction is employed.
Temperature Evolution During Plane Strain Compression Of Tertiary Oxide Scale On Steel
NASA Astrophysics Data System (ADS)
Suarez, L.; Vanden Eynde, X.; Lamberigts, M.; Houbaert, Y.
2007-04-01
An oxide scale layer always forms at the steel surface during hot rolling. This scale layer separates the work roll from the metal substrate. Understanding the deformation behaviour and mechanical properties of the scale is of great interest because it affects the frictional conditions during hot rolling and the heat-transfer behaviour at the strip-roll interface. A thin wustite scale layer (<20 μm) was created under controlled conditions in an original laboratory device adequately positioned in a compression testing machine to investigate plane strain compression. Oxidation tests were performed on an ULC steel grade. After the oxide growth at 1050°C, plane strain compression (PSC) was performed immediately to simulate the hot rolling process. PSC experiments were performed at a deformation temperature of 1050°C, with reduction ratios from 5 to 70%, and strain rates of 10s-1 under controlled gas atmospheres. Results show that for wustite, ductility is obvious at 1050°C. Even after deformation oxide layers exhibit good adhesion to the substrate and homogeneity over the thickness. The tool/sample temperature difference seems to be the reason for the unexpected ductile behaviour of the scale layer.
Temperature Evolution During Plane Strain Compression Of Tertiary Oxide Scale On Steel
Suarez, L.; Houbaert, Y.; Eynde, X. van den; Lamberigts, M.
2007-04-07
An oxide scale layer always forms at the steel surface during hot rolling. This scale layer separates the work roll from the metal substrate. Understanding the deformation behaviour and mechanical properties of the scale is of great interest because it affects the frictional conditions during hot rolling and the heat-transfer behaviour at the strip-roll interface. A thin wustite scale layer (<20 {mu}m) was created under controlled conditions in an original laboratory device adequately positioned in a compression testing machine to investigate plane strain compression. Oxidation tests were performed on an ULC steel grade. After the oxide growth at 1050 deg. C, plane strain compression (PSC) was performed immediately to simulate the hot rolling process. PSC experiments were performed at a deformation temperature of 1050 deg. C, with reduction ratios from 5 to 70%, and strain rates of 10s-1 under controlled gas atmospheres. Results show that for wustite, ductility is obvious at 1050 deg. C. Even after deformation oxide layers exhibit good adhesion to the substrate and homogeneity over the thickness. The tool/sample temperature difference seems to be the reason for the unexpected ductile behaviour of the scale layer.
Revision of Standard Method of Test for Plane Strain Fracture Toughness
NASA Technical Reports Server (NTRS)
Shannon, John L., Jr.
1998-01-01
The purpose of this grant is to revise ASTM Standard Method of Test E-399 for Plane Strain Fracture Toughness of Metallic Materials based on users' experience, and to harmonize the Method with international standards in the interest of U. S. competitive participation in the global marketplace. Rewriting and reformatting the Method are well along. Research laboratories here and abroad have been engaged in developing technical bases for the Method's novel revision items. Close liaison is being maintained with experts in the field here and abroad to ensure consensus agreement on all substantive matters in anticipation of an eventual circulation of the document for ASTM worldwide approval.
Rathke, Jörn; Sinn, Gerhard; Konnerth, Johannes; Müller, Ulrich
2012-01-01
Internal bond strength testing is a widely used approach for testing quality traits of wood based panels. Generally, failure of internal bond specimens is due to adhesion and/or wood failure in the specimen. It has been reported that a composite product with a large variation in the vertical density profile fails in the center part of the board which is either the middle of the core layer or the transition zone between core layer and face layer. The density in the failure zone is typically 50% lower than the maximum density in the face layers. The aim of this study was to analyze the strain distribution in a specimen under tension perpendicular to the panel plane. The results showed that a high variety of strain magnitude occurred in the specimen. The strain is either aligned with the tension direction or a tension zone is built in one of the edge zones leading to failure. Vector graphics of the specimen show the problematic test setup of internal bond strength measurement. Strain spots in the edges lead to the assumption of an uneven stress distribution due to the momentum which results from non-perfect alignment or irregularities in the test setup. PMID:28817026
Rathke, Jörn; Sinn, Gerhard; Konnerth, Johannes; Müller, Ulrich
2012-06-19
Internal bond strength testing is a widely used approach for testing quality traits of wood based panels. Generally, failure of internal bond specimens is due to adhesion and/or wood failure in the specimen. It has been reported that a composite product with a large variation in the vertical density profile fails in the center part of the board which is either the middle of the core layer or the transition zone between core layer and face layer. The density in the failure zone is typically 50% lower than the maximum density in the face layers. The aim of this study was to analyze the strain distribution in a specimen under tension perpendicular to the panel plane. The results showed that a high variety of strain magnitude occurred in the specimen. The strain is either aligned with the tension direction or a tension zone is built in one of the edge zones leading to failure. Vector graphics of the specimen show the problematic test setup of internal bond strength measurement. Strain spots in the edges lead to the assumption of an uneven stress distribution due to the momentum which results from non-perfect alignment or irregularities in the test setup.
Acoustic Emission Analysis of Plane Strain-Compressed Mg Single Crystals
NASA Astrophysics Data System (ADS)
Drozdenko, Daria; Dobroň, Patrik; Knapek, Michal; Letzig, Dietmar; Bohlen, Jan; Chmelík, František
Mg single crystals with three different crystallographic orientations have been channel die (plane strain) compressed at applied rate of 10-3s-1 and at room temperature. The concurrent acoustic emission (AE) measurement was used as a method to analyze the dislocation dynamic during plastic deformation of Mg single crystals. The AE count rate and the maximum amplitudes of the AE event were correlated with stress-strain curves to determine the activity of various deformation mechanisms. The presence of large AE signals in the first stage of plastic deformation in single crystals with favorable orientation for (10.2)-twinning indicates twin nucleation and subsequent decrease of the AE activity, which can be connected with twin growth and collective dislocation processes. Compression along the c-axis (hard deformation mode) produces almost no AE activity.
NASA Technical Reports Server (NTRS)
Shbeeb, N.; Binienda, W. K.; Kreider, K.
1999-01-01
The driving forces for a generally oriented crack embedded in a Functionally Graded strip sandwiched between two half planes are analyzed using singular integral equations with Cauchy kernels, and integrated using Lobatto-Chebyshev collocation. Mixed-mode Stress Intensity Factors (SIF) and Strain Energy Release Rates (SERR) are calculated. The Stress Intensity Factors are compared for accuracy with previously published results. Parametric studies are conducted for various nonhomogeneity ratios, crack lengths. crack orientation and thickness of the strip. It is shown that the SERR is more complete and should be used for crack propagation analysis.
Propagation of in-plane wave in viscoelastic monolayer graphene via nonlocal strain gradient theory
NASA Astrophysics Data System (ADS)
Xiao, Weiwei; Li, Li; Wang, Meng
2017-06-01
The behaviors of monolayer graphene sheet have attracted increasing attention of many scientists and researchers. In this study, the propagation behaviors of in-plane wave in viscoelastic monolayer graphene are investigated. The constitutive equation and governing equation for in-plane wave propagation is developed by employing Hamilton's principle and nonlocal strain gradient theory. By solving the governing equation of motion, the closed-form dispersion relation between phase velocity and wave number is derived and an asymptotic phase velocity can be acquired. The effects of wave number, material length scale parameter, nonlocal parameter and damping coefficient on in-plane wave propagation behaviors are discussed in the numerical studies. It is found that, when exciting wavelengths or structural dimensions become comparable to the material length scale parameters and nonlocal parameters, the scaling effects on wave propagation behaviors are significant. For nanoscaled graphene sheet, the effects of nonlocal parameter, material length scale parameter and damping coefficient on phase velocity are tiny at low wave numbers while significant at high wave numbers. The phase velocity would increase with the increase of material length scale parameter or the decrease of nonlocal parameter and damping coefficient. Furthermore, results indicate that the asymptotic phase velocity can be increase by increasing material length scale parameter or decreasing nonlocal parameter.
Effects of Be and Fe content on plane strain fracture toughness in A357 alloys
Tan, Y.H.; Lee, S.L.; Lin, Y.L.
1995-11-01
The effect of Be and Fe content on the plane strain fracture toughness K{sub IC} of aluminum-based A357 alloys is investigated. The fracture behavior of A357 alloys has been evaluated as a function of both the magnitude and morphology of iron-bearing compounds and silicon particles. Addition of Be is beneficial for tensile properties and fracture toughness in the case of alloys containing intermediate (0.07 pct) and higher (0.15 pct) Fe levels. On the other hand, Be added to alloys containing the lower Fe (0.01 pct) level appears detrimental to tensile strength, but the quality index, notch-yield ratio (NYR), and plane strain fracture toughness were improved. Fractographic analysis reveals that crack extension of A357 alloys occurs mainly in an intergranular fracture mode. The fracture processes are initiated by void nucleation at iron-bearing compounds or irregularly shaped eutectic silicon particles as a result of their cracking and decohesion from the matrix. Then, void growth and coalescence result in growth of the main crack by shear-linkage-induced breakdown of submicron-strengthening particles. The effect of Be on increasing K{sub IC} is more apparent in the higher Fe alloys than in the lower Fe alloys. Superior toughness obtained by microstructural control has also been achieved in the intermediate and higher Fe levels of Be-containing alloys, with values equal to those obtained in alloys of lower Fe content.
Effects of be and fe content on plane strain fracture toughness in A357 alloys
NASA Astrophysics Data System (ADS)
Tan, Yen-Hung; Lee, Sheng-Long; Lin, Yu-Lom
1995-11-01
The effect of Be and Fe content on the plane strain fracture toughness K IC of aluminum-based A357 alloys is investigated. The fracture behavior of A357 alloys has been evaluated as a function of both the magnitude and morphology of iron-bearing compounds and silicon particles. Addition of Be is beneficial for tensile properties and fracture toughness in the case of alloys containing intermediate (0.07 pct) and higher (0.15 pct) Fe levels. On the other hand, Be added to alloys containing the lower Fe (0.01 pct) level appears detrimental to tensile strength, but the quality index, notch-yield ratio (NYR), and plane strain fracture toughness were improved. Fractographic analysis reveals that crack extension of A357 alloys occurs mainly in an intergranular fracture mode. The fracture processes are initiated by void nucleation at iron-bearing compounds or irregularly shaped eutectic silicon particles as a result of their cracking and decohesion from the matrix. Then, void growth and coalescence result in growth of the main crack by shear-linkage-induced breakdown of submicronstrengthening particles. The effect of Be on increasing K IC is more apparent in the higher Fe alloys than in the lower Fe alloys. Superior toughness obtained by microstructural control has also been achieved in the intermediate and higher Fe levels of Be-containing alloys, with values equal to those obtained in alloys of lower Fe content.
Uniqueness of the interior plane strain time-harmonic viscoelastic inverse problem
NASA Astrophysics Data System (ADS)
Zhang, Yixiao; Barbone, Paul E.; Harari, Isaac; Oberai, Assad A.
2016-07-01
Elasticity imaging has emerged as a promising medical imaging technique with applications in the detection, diagnosis and treatment monitoring of several types of disease. In elasticity imaging measured displacement fields are used to generate images of elastic parameters of tissue by solving an inverse problem. When the tissue excitation, and the resulting tissue motion is time-harmonic, elasticity imaging can be extended to image the viscoelastic properties of the tissue. This leads to an inverse problem for the complex-valued shear modulus at a given frequency. In this manuscript we have considered the uniqueness of this inverse problem for an incompressible, isotropic linear viscoelastic solid in a state of plane strain. For a single measured displacement field we conclude that the solution is infinite dimensional, and the data required to render it unique is determined by the measured strain field. In contrast, for two independent displacement fields such that the principal directions of the resulting strain fields are different, the space of possible solutions is eight dimensional, and given additional data, like the value of the shear modulus at four locations, or over a calibration region, we may determine the shear modulus everywhere. We have also considered simple analytical examples that verify these results and offer additional insights. The results derived in this paper may be used as guidelines by the practitioners of elasticity imaging in designing more robust and accurate imaging protocols.
Assessment of Constitutive and Stability Behavior of Sands Under Plane Strain Condition
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.; Sture, Stein
2000-01-01
A series of biaxial (plane strain) experiments were conducted on three sands under low (15 kPa) and high (100 kPa) confining pressure conditions to investigate the effects of specimen density, confining pressure, and sand grains size and shape on the constitutive and stability behavior of granular materials. The three sands used in the experiments were fine, medium, and coarse-grained uniform silica sands with rounded, sub-angular, and angular grains, respectively. Specimen deformation was readily monitored and analyzed with the help of a grid pattern imprinted on the latex membrane. The overall stress-strain behavior is strongly dependent on the specimen density, confining pressure, sand grain texture, and the resulting failure mode(s). That became evident in different degrees of softening responses at various axial strains. The relationship between the constitutive behavior and the specimens' modes of instability is presented. The failure in all specimens was characterized by two distinct and opposite shear bands. It was found that the measured dilatancy angles increase as the sand grains' angularity and size increase. The measured shear band inclination angles are also presented and compared with classical Coulomb and Roscoe solutions.
NASA Astrophysics Data System (ADS)
Ridzuan, M. J. M.; Hafis, S. M.; Saifullah, K. N.; Syahrullail, S.
2012-06-01
Large quantities of lubricant are being widely used in the metal forming industry and this high consumption is negatively affecting the environment. Finding an alternative to this current situation is getting more serious and urgent in response to environmental and operational cost pressures. This paper deals with an experimental investigation to obtain the minimum quantity of lubricant (MQL) of RBD palm stearin, which is used as lubricant between the contact sliding surfaces of the taper die and billet via plane-strain-extrusion apparatus. The symmetrical workpieces are designed as combined billets made from pure aluminium A1100. The dies of the apparatus are made of SKD 11 steel. The extrusion ratio of the processes is 3 and the workpieces are extruded by hydraulic press machine. Four conditions of the quantity selected are 0.1 mg, 1 mg, 5 mg, and 20 mg. The analysis of the result shows that the conditions of the quantity are in the load reducing order from 0.1 mg, 1mg and 5 mg. The highest distribution of surface roughness is at 0.1 mg, whereby for others, the conditions are quite similar. However, the distribution of velocity and effective strain are lowest at 5 mg. The minimum quantity of lubricant (MQL) of the RBD palm stearin as lubricant on the contact sliding surfaces in planestrain-extrusion is determined based on the results of load, surface roughness, velocity and effective strain.
Assessment of Constitutive and Stability Behavior of Sands Under Plane Strain Condition
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.; Sture, Stein
2000-01-01
A series of biaxial (plane strain) experiments were conducted on three sands under low (15 kPa) and high (100 kPa) confining pressure conditions to investigate the effects of specimen density, confining pressure, and sand grains size and shape on the constitutive and stability behavior of granular materials. The three sands used in the experiments were fine, medium, and coarse-grained uniform silica sands with rounded, sub-angular, and angular grains, respectively. Specimen deformation was readily monitored and analyzed with the help of a grid pattern imprinted on the latex membrane. The overall stress-strain behavior is strongly dependent on the specimen density, confining pressure, sand grain texture, and the resulting failure mode(s). That became evident in different degrees of softening responses at various axial strains. The relationship between the constitutive behavior and the specimens' modes of instability is presented. The failure in all specimens was characterized by two distinct and opposite shear bands. It was found that the measured dilatancy angles increase as the sand grains' angularity and size increase. The measured shear band inclination angles are also presented and compared with classical Coulomb and Roscoe solutions.
Strained-layer superlattice focal plane array having a planar structure
Kim, Jin K [Albuquerque, NM; Carroll, Malcolm S [Albuquerque, NM; Gin, Aaron [Albuquerque, NM; Marsh, Phillip F [Lowell, MA; Young, Erik W [Albuquerque, NM; Cich, Michael J [Albuquerque, NM
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.
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.
NASA Technical Reports Server (NTRS)
Alshibli, Khalid A.; Batiste, Susan N.; Sture, Stein; Curreri, Peter A. (Technical Monitor)
2002-01-01
A comprehensive experimental investigation was conducted to investigate the effects of loading condition and confining pressure on strength properties and instability phenomena in sands. A uniform sub-rounded to rounded natural silica sand known as F-75 Ottawa sand was used in the investigation. The results of a series on Conventional Triaxial Compression (CTC) experiments tested under very low confining pressures (0.05 - 1.30) kPa tested in a Microgravity environment abroad the NASA Space Shuttle are presented in addition to the results similar specimens tested in terrestrial laboratory to investigate the effect of confining pressure on the constitutive behavior of sands. The behavior of the CTC experiments is compared with the results of Plane Strain (PS) experiments. Computed tomography and other digital imaging techniques were used to study the development and evolution of shear bands.
NASA Astrophysics Data System (ADS)
Kroon, M.
2011-11-01
Rubbers and soft biological tissues may undergo large deformations and are also viscoelastic. The formulation of constitutive models for these materials poses special challenges. In several applications, especially in biomechanics, these materials are also relatively thin, implying that in-plane stresses dominate and that plane stress may therefore be assumed. In the present paper, a constitutive model for viscoelastic materials in the finite strain regime and under the assumption of plane stress is proposed. It is assumed that the relaxation behaviour in the direction of plane stress can be treated separately, which makes it possible to formulate evolution laws for the plastic strains on explicit form at the same time as incompressibility is fulfilled. Experimental results from biomechanics (dynamic inflation of dog aorta) and rubber mechanics (biaxial stretching of rubber sheets) were used to assess the proposed model. The assessment clearly indicates that the model is fully able to predict the experimental outcome for these types of material.
Andrews, D.J.
1985-01-01
A numerical boundary integral method, relating slip and traction on a plane in an elastic medium by convolution with a discretized Green function, can be linked to a slip-dependent friction law on the fault plane. Such a method is developed here in two-dimensional plane-strain geometry. Spontaneous plane-strain shear ruptures can make a transition from sub-Rayleigh to near-P propagation velocity. Results from the boundary integral method agree with earlier results from a finite difference method on the location of this transition in parameter space. The methods differ in their prediction of rupture velocity following the transition. The trailing edge of the cohesive zone propagates at the P-wave velocity after the transition in the boundary integral calculations. Refs.
Wireless Open-Circuit In-Plane Strain and Displacement Sensor Requiring No Electrical Connections
NASA Technical Reports Server (NTRS)
Woodard, Stanley E. (Inventor)
2014-01-01
A wireless in-plane strain and displacement sensor includes an electrical conductor fixedly coupled to a substrate subject to strain conditions. The electrical conductor is shaped between its ends for storage of an electric field and a magnetic field, and remains electrically unconnected to define an unconnected open-circuit having inductance and capacitance. In the presence of a time-varying magnetic field, the electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses. The sensor also includes at least one electrically unconnected electrode having an end and a free portion extending from the end thereof. The end of each electrode is fixedly coupled to the substrate and the free portion thereof remains unencumbered and spaced apart from a portion of the electrical conductor so-shaped. More specifically, at least some of the free portion is disposed at a location lying within the magnetic field response generated by the electrical conductor. A motion guidance structure is slidingly engaged with each electrode's free portion in order to maintain each free portion parallel to the electrical conductor so-shaped.
Generalized plane waves in Poincaré gauge theory of gravity
NASA Astrophysics Data System (ADS)
Blagojević, Milutin; Cvetković, Branislav; Obukhov, Yuri N.
2017-09-01
A family of exact vacuum solutions, representing generalized plane waves propagating on the (anti-)de Sitter background, is constructed in the framework of Poincaré gauge theory. The wave dynamics is defined by the general Lagrangian that includes all parity even and parity odd invariants up to the second order in the gauge field strength. The structure of the solution shows that the wave metric significantly depends on the spacetime torsion.
NASA Astrophysics Data System (ADS)
Benito, L.; Ballesteros, C.; Ward, R. C. C.
2014-04-01
We report on the magnetic and structural characterization of high lattice-mismatched [Dy2nm/SctSc] superlattices, with variable Sc thickness tSc= 2-6 nm. We find that the characteristic in-plane effective hexagonal magnetic anisotropy K66,ef reverses sign and undergoes a dramatic reduction, attaining values of ≈13-24 kJm-3, when compared to K66=-0.76 MJm-3 in bulk Dy. As a result, the basal plane magnetic anisotropy is dominated by a uniaxial magnetic anisotropy (UMA) unfound in bulk Dy, which amounts to ≈175-142 kJm-3. We attribute the large downsizing in K66,ef to the compression epitaxial strain, which generates a competing sixfold magnetoelastic (MEL) contribution to the magnetocrystalline (strain-free) magnetic anisotropy. Our study proves that the in-plane UMA is caused by the coupling between a giant symmetry-breaking MEL constant Mγ ,22≈1 GPa and a morphic orthorhombiclike strain ɛγ ,1≈10-4, whose origin resides on the arising of an in-plane anisotropic strain relaxation process of the pseudoepitaxial registry between the nonmagnetic bottom layers in the superstructure. This investigation shows a broader perspective on the crucial role played by epitaxial strains at engineering the magnetic anisotropy in multilayers.
A Generalized Correlation-Based Model for Out-of-Plane Motion Estimation in Freehand Ultrasound.
Afsham, Narges; Najafi, Mohammad; Abolmaesumi, Purang; Rohling, Robert
2014-01-01
A big challenge in sensorless image-based ultrasound tracking is in the out-of-plane motion estimation. The correlation value of a specific model of speckle known as fully developed speckle (FDS) can be used to estimate the out-of-plane displacement. In real tissue, this kind of pattern is rare and the deviation of speckle pattern from the ideal FDS model diminishes the accuracy of the out-of-plane motion estimation. In this paper a new method for estimation of the out-of-plane motion is proposed. Firstly a closed-form mathematical derivation is provided for the correlation of two RF echo signal patches at different positions. A linear regression model of the ultrasound beam profile is proposed to account for the spatial variability of the ultrasound beam and enhance the accuracy of out-of-plane motion estimation in real tissue. The statistical model of speckle used here is based on the Rician-Inverse Gaussian (RiIG) stochastic process of the speckle formation, which can be considered as a generalized form of the K-distribution with richer parametrization. In this work, for the first time the second-order statistics of the RIG model is used for speckle tracking. This statistical model allows for derivation of a closed-form formulation for the correlation coefficient based on the statistical parameters of every patch. Since the effect of coherency is considered in the RiIG model, it increases the reliability of the out-of-plane motion estimation. The flexibility of the proposed method enables almost any patch through the whole image to be used for the purpose of displacement estimation. The method has been evaluated both on ex vivo and in vivo tissues in various experiments including out-of-plane rotation (tilt, yaw) and free-hand imaging. The overall outcome demonstrates the potential of the proposed method for in vivo tissues.
Gender, General Strain Theory, Negative Emotions, and Disordered Eating
ERIC Educational Resources Information Center
Piquero, Nicole Leeper; Fox, Kristan; Piquero, Alex R.; Capowich, George; Mazerolle, Paul
2010-01-01
Much of the prior work on General Strain Theory (GST) has focused on how strain and negative emotions interrelate to produce criminal--especially violent--activity. Very little research has extended GST to examine other types of non-criminal, negative behavior, such as self-harming behaviors associated with disordered eating, a traditionally…
Gender, General Strain Theory, Negative Emotions, and Disordered Eating
ERIC Educational Resources Information Center
Piquero, Nicole Leeper; Fox, Kristan; Piquero, Alex R.; Capowich, George; Mazerolle, Paul
2010-01-01
Much of the prior work on General Strain Theory (GST) has focused on how strain and negative emotions interrelate to produce criminal--especially violent--activity. Very little research has extended GST to examine other types of non-criminal, negative behavior, such as self-harming behaviors associated with disordered eating, a traditionally…
Well-posedness and generalized plane waves simulations of a 2D mode conversion model
Imbert-Gérard, Lise-Marie
2015-12-15
Certain types of electro-magnetic waves propagating in a plasma can undergo a mode conversion process. In magnetic confinement fusion, this phenomenon is very useful to heat the plasma, since it permits to transfer the heat at or near the plasma center. This work focuses on a mathematical model of wave propagation around the mode conversion region, from both theoretical and numerical points of view. It aims at developing, for a well-posed equation, specific basis functions to study a wave mode conversion process. These basis functions, called generalized plane waves, are intrinsically based on variable coefficients. As such, they are particularly adapted to the mode conversion problem. The design of generalized plane waves for the proposed model is described in detail. Their implementation within a discontinuous Galerkin method then provides numerical simulations of the process. These first 2D simulations for this model agree with qualitative aspects studied in previous works.
NASA Astrophysics Data System (ADS)
Damanhuri, Nor Alisa; Ayob, Syafikah
2017-09-01
A general numerical approximation of the stress equilibrium equations and constructing axisymmetric ideal plastic plane deformation of a granular material is considered. The stress components are assumed to satisfy the Coulomb yield criterion and the self-weight of the material is neglected. The standard method of numerical approximation leads to the construction of the small segments of the stress characteristic field. Using the Matlab program, the method is applied to a problem of granular indentation by a smooth flat surface.
NASA Astrophysics Data System (ADS)
Kistanov, Andrey A.; Cai, Yongqing; Zhang, Yong-Wei; Dmitriev, Sergey V.; Zhou, Kun
2017-03-01
By using first-principles calculations, the electronic structure of planar and strained in-plane graphene/silicene heterostructure is studied. The heterostructure is found to be metallic in a strain range from ‑7% (compression) to +7% (tension). The effect of compressive/tensile strain on the chemical activity of the in-plane graphene/silicene heterostructure is examined by studying its interaction with the H2O molecule. It shows that compressive/tensile strain is able to increase the binding energy of H2O compared with the adsorption on a planar surface, and the charge transfer between the water molecule and the graphene/silicene sheet can be modulated by strain. Moreover, the presence of the boron-nitride (BN)-substrate significantly influences the chemical activity of the graphene/silicene heterostructure upon its interaction with the H2O molecule and may cause an increase/decrease of the charge transfer between the H2O molecule and the heterostructure. These findings provide insights into the modulation of electronic properties of the in-plane free-standing/substrate-supported graphene/silicene heterostructure, and render possible ways to control its electronic structure, carrier density and redox characteristics, which may be useful for its potential applications in nanoelectronics and gas sensors.
NASA Technical Reports Server (NTRS)
Ricoy, M. A.; Volakis, J. L.
1991-01-01
The diffraction problem associated with a multilayer material slab recessed in a perfectly conducting ground plane is formulated and solved via the generalized scattering matrix formulation in conjunction with the dual integral equation approach. The multilayer slab is replaced by a surface obeying a generalized impedance boundary condition to facilitate the computation of the pertinent Wiener Hopf split functions and their zeros. Both Ez and Hz polarizations are considered, and a number of scattering patterns are presented, some of which are compared to exact results available for a homogeneous recessed slab.
NASA Astrophysics Data System (ADS)
Li, Hong; Tsai, Charlie; Koh, Ai Leen; Cai, Lili; Contryman, Alex W.; Fragapane, Alex H.; Zhao, Jiheng; Han, Hyun Soon; Manoharan, Hari C.; Abild-Pedersen, Frank; Nørskov, Jens K.; Zheng, Xiaolin
2016-01-01
As a promising non-precious catalyst for the hydrogen evolution reaction (HER; refs ,,,,), molybdenum disulphide (MoS2) is known to contain active edge sites and an inert basal plane. Activating the MoS2 basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS2 for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposed Mo atoms. The hydrogen adsorption free energy (ΔGH) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Proper combinations of S-vacancy and strain yield the optimal ΔGH = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.
Li, Hong; Tsai, Charlie; Koh, Ai Leen; Cai, Lili; Contryman, Alex W; Fragapane, Alex H; Zhao, Jiheng; Han, Hyun Soon; Manoharan, Hari C; Abild-Pedersen, Frank; Nørskov, Jens K; Zheng, Xiaolin
2016-01-01
As a promising non-precious catalyst for the hydrogen evolution reaction (HER; refs ,,,,), molybdenum disulphide (MoS2) is known to contain active edge sites and an inert basal plane. Activating the MoS2 basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS2 for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposed Mo atoms. The hydrogen adsorption free energy (ΔGH) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Proper combinations of S-vacancy and strain yield the optimal ΔGH = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.
Li, Hong; Tsai, Charlie; Koh, Ai Leen; ...
2015-11-09
As a promising non-precious catalyst for the hydrogen evolution reaction, molybdenum disulphide (MoS2) is known to contain active edge sites and an inert basal plane. Activating the MoS2 basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS2 for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposedmore » Mo atoms. The hydrogen adsorption free energy (ΔGH) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Furthermore, proper combinations of S-vacancy and strain yield the optimal ΔGH = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.« less
NASA Astrophysics Data System (ADS)
Kuklja, Maija M.; Rashkeev, Sergey N.
2007-03-01
First-principles calculations of the structural and electronic properties of the deformed molecular crystal 1,1-diamino-2,2-dinitroethylene (FOX-7) under shear-strain loading are presented. The reaction of the crystal to applied shear-strain loading is found to be highly anisotropic. When the external loading is removed, the relaxation of the system is mainly defined by stretching, bending, and rotations of the NO2 groups of neighboring molecules from the two adjacent zigzag-shaped crystalline planes that were initially shifted. In general, the deformed molecular crystal relaxes to its initial, ideal crystalline FOX-7 structure. However, different planes remain shifted relatively to each other on vectors, which are typically incommensurated with any translational vector of the ideal crystal. This fact makes an existence of ideal crystals of this material quite problematic. We also found that no metallization occurs under shear-strain loading. We suggest that the considered mechanisms of the shear-strain relaxation of the structural and electronic degrees of freedom are typical for layered anisotropic molecular crystals, and that they should significantly affect their chemical reactivity, conductivity, optical properties, and initiation of detonation in energetic materials.
NASA Astrophysics Data System (ADS)
Wu, Huaping; Ma, Xuefu; Zhang, Zheng; Zhu, Jun; Wang, Jie; Chai, Guozhong
2016-04-01
A nonlinear thermodynamic model based on the vertically aligned nanocomposite (VAN) thin films of ferroelectric-metal oxide system has been developed to investigate the physical properties of the epitaxial Ba0.6Sr0.4TiO3 (BST) films containing vertical Sm2O3 (SmO) nanopillar arrays on the SrTiO3 substrate. The phase diagrams of out-of-plane lattice mismatch vs. volume fraction of SmO are calculated by minimizing the total free energy. It is found that the phase transformation and dielectric response of BST-SmO VAN systems are extremely dependent on the in-plane misfit strain, the out-of-plane lattice mismatch, the volume fraction of SmO phase, and the external electric field applied to the nanocomposite films at room temperature. In particular, the BST-SmO VAN systems exhibit higher dielectric properties than pure BST films. Giant dielectric response and maximum tunability are obtained near the lattice mismatch where the phase transition occurs. Under the in-plane misfit strain of umf=0.3 % and the out-of-plane lattice mismatch of u3=0.002 , the dielectric tunability can be dramatically enhanced to 90% with the increase of SmO volume fraction, which is well consistent with previous experimental results. This work represents an approach to further understand the dependence of physical properties on the lattice mismatch (in-plane and out-of-plane) and volume fraction, and to manipulate or optimize functionalities in the nanocomposite oxide thin films.
The linear stability of plane stagnation-point flow against general disturbances
NASA Astrophysics Data System (ADS)
Brattkus, K.; Davis, S. H.
1991-02-01
The linear-stability theory of plane stagnation-point flow against an infinite flat plate is re-examined. Disturbances are generalized from those of Goertler type to include other types of variations along the plate. It is shown that Hiemenz flow is linearly stable and that the Goertler-type modes are those that decay slowest. This work then rationalizes the use of such self-similar disturbances on Hiemenz flow and shows how questions of disturbance structure can be approached on other self-similar flows.
The linear stability of plane stagnation-point flow against general disturbances
NASA Technical Reports Server (NTRS)
Brattkus, K.; Davis, S. H.
1991-01-01
The linear-stability theory of plane stagnation-point flow against an infinite flat plate is re-examined. Disturbances are generalized from those of Goertler type to include other types of variations along the plate. It is shown that Hiemenz flow is linearly stable and that the Goertler-type modes are those that decay slowest. This work then rationalizes the use of such self-similar disturbances on Hiemenz flow and shows how questions of disturbance structure can be approached on other self-similar flows.
The linear stability of plane stagnation-point flow against general disturbances
NASA Technical Reports Server (NTRS)
Brattkus, K.; Davis, S. H.
1991-01-01
The linear-stability theory of plane stagnation-point flow against an infinite flat plate is re-examined. Disturbances are generalized from those of Goertler type to include other types of variations along the plate. It is shown that Hiemenz flow is linearly stable and that the Goertler-type modes are those that decay slowest. This work then rationalizes the use of such self-similar disturbances on Hiemenz flow and shows how questions of disturbance structure can be approached on other self-similar flows.
1980-07-01
certain properties of the solution to the analogous crack problem in the linearized theory. We then show that, at least for the Mooney - Rivlin material...an incompressible material con- forming to (1.18) is supplied by the Mooney - Rivlin material, with the complete plane-strain elastic potential (I) R... Mooney - Rivlin material, a solution with this parity cannot possibly exist. To this end suppose o0 !now that W is given by (1.19). Eliminating a between
NASA Astrophysics Data System (ADS)
Besuelle, P.
2012-04-01
Failure by strain localization is commonly observed in geomaterials. Generaly, experimental characterization of the localization in a porous sandstone are performed with classical axisymmetric triaxial compression tests. The effect of the confining pressure is observed on several aspects: onset of localization, pattern of localization, porosity evolution inside bands, grain scale mechanisms of deformation. Complex patterns of localization can be observed at high confining pressure in the transition between the brittle and ductile regime, showing several deformation bands in the specimens ([1]). However the history (time evolution) of the localization is not accessible because the observations are post-mortem. Strain field measurement and evolution in time of the strain field are particularly useful to study the strain localization (initiation of the deformation bands) and the post-localization regime. Such tools have been developed for soils (e.g., sand specimens in plane strain condition [2] or in triaxial conditions using X-ray tomography [3]). Similar developments for rocks are still difficult, especially because the pertinent confining pressure to reproduce in situ stresses are higher than for soils. We present here first results obtained in a new true triaxial apparatus that allows observation of the rock specimen under loading and especially the complex development of deformation bands and faults. As for [4] and [5], the three principal stresses are different, however the intermediate stress is controlled in order to impose a plane strain condition (zero strain in this direction). Observation of a specimen under load is possible as one surface of the prismatic specimen, which is orthogonal to the plane strain direction, is in contact with a hard transparent window. The deformation of this surface is representative of the deformation in the whole specimen, up to and beyond strain localization. Therefore the evolution of the strain field in the sample can be
General Strain Theory, Peer Rejection, and Delinquency/Crime
ERIC Educational Resources Information Center
Higgins, George E.; Piquero, Nicole L.; Piquero, Alex R.
2011-01-01
The development of general strain theory (GST) has led to a renewed focus on the influence of negative life experiences on antisocial behavior. Although a number of studies have generated an impressive array of support for the theory, several avenues remain open for research. In this article, we examine how a specific noxious stimuli, peer…
General Strain Theory, Peer Rejection, and Delinquency/Crime
ERIC Educational Resources Information Center
Higgins, George E.; Piquero, Nicole L.; Piquero, Alex R.
2011-01-01
The development of general strain theory (GST) has led to a renewed focus on the influence of negative life experiences on antisocial behavior. Although a number of studies have generated an impressive array of support for the theory, several avenues remain open for research. In this article, we examine how a specific noxious stimuli, peer…
Gendered Responses to Serious Strain: The Argument for a General Strain Theory of Deviance.
Kaufman, Joanne M
2009-09-01
This paper expands and builds on newer avenues in research on gender and general strain theory (GST). I accomplish this by focusing on serious strains that are relevant for males and females, including externalizing and internalizing forms of negative emotions, and including multiple gendered deviant outcomes. Using the Add Health dataset, I find strong support for the impact of serious strains on both types of negative emotions and different forms of deviance for males and females. However, the experience of serious strain, emotionally and behaviorally, is gendered. Depressive symptoms are particularly important for all types of deviance by females. Including multiple types of deviant outcomes offers a fuller understanding of both similarities and differences by gender. These results support the utility of GST as a theory of deviance in general and support greater connections between GST, feminist theorizing, and the sociology of mental health.
NASA Astrophysics Data System (ADS)
Llana-Funez, S.; Rutter, E. H.
2006-12-01
The condition of simultaneous operation of five slip systems to produce homogeneous deformation by intracrystalline plasticity in polycrystalline aggregates is frequently simplified when applied to studying deformation in nature by considering other deformation mechanisms that relax the strict geometric condition. Insufficient knowledge of how these complementary mechanisms interact and accommodate geometrically non-plane strain situations obscure somehow subsequent interpretation of slip patterns in relation to principal strain axes. We ran an experimental program isolating intracrystalline plasticity from other deformation mechanisms with the aim of testing the effect of non-plane strain geometries in the 3D arrangement of crystallographic elements from which we inferred the orientation of active slip systems. We use a fine grained polycrystalline aggregate (Solnhofen Limestone), naturally doped at grain boundaries with organic matter preventing grain growth, that deforms plastically at the experimental conditions used (600 °C, 200 MPa confining pressure and 10^{- 4}s-1 strain rates). To maximize the number of strain geometries we used different experimental configurations (axi-symmetric shortening and extension, and direct shear) and also study in detail volumes where deformation is heterogeneous but still relatively simple. The aim of the work is to relate strain geometry and the development of crystallographic fabrics in different strain paths. We produced constrictional, flattening, and nearly plane strain deformations. We were also able to obtain strain geometries where the vorticity axis in a non-coaxial deformation was either perpendicular to the extension direction (as in simple and sub-simple shear) or parallel to it. We measured the crystallographic preferred orientation (CPO) of calcite in deformed specimens by electron back-scattered diffraction techniques (EBSD), which allowed us to scan relatively small areas within already small specimens
NASA Astrophysics Data System (ADS)
Manchon, A.; Slonczewski, J. C.
2006-05-01
Extensions of an existing circuit theory for current perpendicular to plane magnetoresistance and current-driven torque in noncollinear magnetic-multilayer pillar devices are presented. Our expressions for monodomain critical-current threshold Jc and giant magnetoresistance ΔR are firstly derived in terms of assumed spin-channel resistances for each of the two ferromagnets. Spinflips are thus neglected. We find a class of closed linear relationships connecting Jc-1 and ΔR . We then derive more general expressions for these quantities which take into account spin-flip relaxation. In this case, we assume analytically calculable linear 2×2 current-voltage matrices for the separate two-channel ferromagnets. These expressions again lead to a class of closed linear relationships connecting Jc-1 and ΔR . The latter generalization gives a simple theoretical framework to take into account bulk and interfacial spin flip and more complicated multilayer structures often used in experiments.
Generalization of the subsonic kernel function in the s-plane, with applications to flutter analysis
NASA Technical Reports Server (NTRS)
Cunningham, H. J.; Desmarais, R. N.
1984-01-01
A generalized subsonic unsteady aerodynamic kernel function, valid for both growing and decaying oscillatory motions, is developed and applied in a modified flutter analysis computer program to solve the boundaries of constant damping ratio as well as the flutter boundary. Rates of change of damping ratios with respect to dynamic pressure near flutter are substantially lower from the generalized-kernel-function calculations than from the conventional velocity-damping (V-g) calculation. A rational function approximation for aerodynamic forces used in control theory for s-plane analysis gave rather good agreement with kernel-function results, except for strongly damped motion at combinations of high (subsonic) Mach number and reduced frequency.
Zhang, Jinwu; Liu, Jianhong; Wang, Xin; Zou, Anquan
2017-08-01
General Strain Theory delineates different types of strain and intervening processes from strain to deviance and crime. In addition to explaining individual strain-crime relationship, a contextualized version of general strain theory, which is called the Macro General Strain Theory, has been used to analyze how aggregate variables influence aggregate and individual deviance and crime. Using a sample of 1,852 students (Level 1) nested in 52 schools (Level 2), the current study tests the Macro General Strain Theory using Chinese data. The results revealed that aggregate life stress and strain have influences on aggregate and individual deviance, and reinforce the individual stress-deviance association. The current study contributes by providing the first Macro General Strain Theory test based on Chinese data and offering empirical evidence for the multilevel intervening processes from strain to deviance. Limitations and future research directions are discussed.
General Strain Theory and Substance Use among American Indian Adolescents
Eitle, Tamela McNulty; Eitle, David; Johnson-Jennings, Michelle
2013-01-01
Despite the well-established finding that American Indian adolescents are at a greater risk of illicit substance use and abuse than the general population, few generalist explanations of deviance have been extended to American Indian substance use. Using a popular generalist explanation of deviance, General Strain Theory, we explore the predictive utility of this model with a subsample of American Indian adolescents from waves one and two of the National Longitudinal Study of Adolescent Health (Add-Health). Overall, we find mixed support for the utility of General Strain Theory to account for American Indian adolescent substance use. While exposure to recent life events, a common measure of stress exposure, was found to be a robust indicator of substance use, we found mixed support for the thesis that negative affect plays a key role in mediating the link between strain and substance use. However, we did find evidence that personal and social resources serve to condition the link between stress exposure and substance use, with parental control, self-restraint, religiosity, and exposure to substance using peers each serving to moderate the association between strain and substance use, albeit in more complex ways than expected. PMID:23826511
Orientation control of the orbital ordering plane in epitaxial LaMnO3 thin films by misfit strain
NASA Astrophysics Data System (ADS)
Kim, Yong-Jin; Lee, Jin Hong; Kim, Sang-Woo; Koo, Tae Yeong; Yang, Chan-Ho
2016-10-01
We investigate the effects of misfit strain on the orbital order of epitaxial lanthanum manganite thin films grown on (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) and GdScO3 (GSO) substrates. Resonant X-ray scattering near the Mn K-edge is employed to identify the cooperative Jahn-Teller distortion at room temperature and determine the orientation of the orbital-ordered plane (OOP). We find that coherent growth on LSAT (GSO) makes the OOPs be vertical (parallel) to the film surface. This finding not only offers useful insight into the interplay between misfit strain and orbital order, but also holds promise for strain control of orbital-dependent physical properties.
NASA Astrophysics Data System (ADS)
Baxevanis, T.; Chemisky, Y.; Lagoudas, D. C.
2012-09-01
The plane strain mechanical fields near a stationary crack tip in a pseudoelastic shape memory alloy (SMA) are analyzed via the finite element method. The small scale transformation assumption is employed for the calculations using displacement boundary conditions on a circular region that encloses the stress-induced phase transformation zone. The constitutive law used adopts the classical rate-independent small strain flow theory for the evolution equations of both the transformation and plastic strains. Results on the size and shape of the stress-induced transformation and plastic zone formed near the stationary crack are obtained and a fracture toughness criterion based on the J-integral is discussed in view of the observed path-dependence of J. Moreover, the obtained results are discussed in relation to results for stationary cracks in conventional elastic-plastic materials.
Full in-plane strain tensor analysis using the microscale ring-core FIB milling and DIC approach
NASA Astrophysics Data System (ADS)
Lunt, Alexander J. G.; Salvati, Enrico; Ma, Lifeng; Dolbyna, Igor P.; Neo, Tee K.; Korsunsky, Alexander M.
2016-09-01
Microscale Full In-plane Strain Tensor (FIST) analysis is crucial for improving understanding of residual stress and mechanical failure in many applications. This study outlines the first Focused Ion Beam (FIB) milling and Digital Image Correlation (DIC) based technique capable of performing precise, reliable and rapid quantification of this behaviour. The nature of semi-destructive FIB milling overcomes the main limitations of X-Ray Diffraction (XRD) strain tensor quantification: unstrained lattice parameter estimates are not required, analysis is performed in within a precisely defined 3D microscale volume, both amorphous and crystalline materials can be studied and access to X-ray/neutron facilities is not required. The FIST FIB milling and DIC experimental technique is based on extending the ring-core milling geometry to quantify the strain variation with angle and therefore benefits from the excellent precision and simple analytical approach associated with this method. In this study in-plane strain analysis was performed on sample of commercial interest: a porcelain veneered Yttria Partially Stabilised Zirconia (YPSZ) dental prosthesis, and was compared with the results of XRD. The two methods sample different gauge volumes and mechanical states: approximately plane stress for ring-core milling, and a through-thickness average for XRD. We demonstrate using complex analysis methods and Finite Element (FE) modelling that valid comparisons can be drawn between these two stress states. Excellent agreement was obtained between principal stress orientation and magnitudes, leading to realistic residual stress estimates that agree well with the literature (σAv ≈ 460 MPa) . As a measure of validity of the matching approach we report the upper and lower bounds on the (101) interplanar spacing of YPSZ that are found to correspond to the range 2.9586 - 2.9596 Å , closely matching published values.
Plane Wave Imaging for ultrasonic non-destructive testing: Generalization to multimodal imaging.
Le Jeune, Léonard; Robert, Sébastien; Lopez Villaverde, Eduardo; Prada, Claire
2016-01-01
This paper describes a new ultrasonic array imaging method for Non-Destructive Testing (NDT) which is derived from the medical Plane Wave Imaging (PWI) technique. The objective is to perform fast ultrasound imaging with high image quality. The approach is to transmit plane waves at several angles and to record the back-scattered signals with all the array elements. Focusing in receive is then achieved by coherent summations of the signals in every point of a region of interest. The medical PWI is generalized to immersion setups where water acts as a coupling medium and to multimodal (direct, half-skip modes) imaging in order to detect different types of defects (inclusions, porosities, cracks). This method is compared to the Total Focusing Method (TFM) which is the reference imaging technique in NDT. First, the two post-processing algorithms are described. Then experimental results with the array probe either in contact or in immersion are presented. A good agreement between the TFM and the PWI is observed, with three to ten times less transmissions required for the PWI. Copyright © 2015 Elsevier B.V. All rights reserved.
Gender, General Strain Theory, negative emotions, and disordered eating.
Piquero, Nicole Leeper; Fox, Kristan; Piquero, Alex R; Capowich, George; Mazerolle, Paul
2010-04-01
Much of the prior work on General Strain Theory (GST) has focused on how strain and negative emotions interrelate to produce criminal-especially violent-activity. Very little research has extended GST to examine other types of non-criminal, negative behavior, such as self-harming behaviors associated with disordered eating, a traditionally female-specific self-directed outcome. Using a sample of 338 young adults (54% female, 95% white), this article applies GST to disordered eating by examining how strain and negative emotions relate to this particular outcome across gender. Findings indicate that two types of strain measures predict depressive symptoms among males and females, that inequitable strainful experiences relate to disordered eating among females but not males, that depressive symptoms but not anger increase disordered eating for both males and females, and that membership in Greek organizations (sororities or fraternities) is associated with disordered eating but only for males. Implications for theory and directions for future research are highlighted.
Strain compensated superlattices on m-plane gallium nitride by ammonia molecular beam epitaxy
NASA Astrophysics Data System (ADS)
Fireman, Micha N.; Bonef, Bastien; Young, Erin C.; Nookala, Nishant; Belkin, Mikhail A.; Speck, James S.
2017-08-01
The results of tensile strained AlN/GaN, AlGaN/GaN, and compressive strained InGaN/GaN superlattices (SLs) grown by Ammonia MBE (NH3-MBE) are presented. A combination of atom probe tomography and high-resolution X-ray diffraction confirms that periodic heterostructures of high crystallographic quality are achieved. Strain induced misfit dislocations (MDs), however, are revealed by cathodoluminescence (CL) of the strained AlN/GaN, AlGaN/GaN, and InGaN/GaN structures. MDs in the active region of a device are a severe problem as they act as non-radiative charge recombination centers, affecting the reliability and efficiency of the device. Strain compensated SL structures are subsequently developed, composed of alternating layers of tensile strained AlGaN and compressively strained InGaN. CL reveals the absence of MDs in such structures, demonstrating that strain compensation offers a viable route towards MD free active regions in III-Nitride SL based devices.
The relativistic transformation for an electromagnetic plane wave with general time dependence
NASA Astrophysics Data System (ADS)
Smith, Glenn S.
2012-03-01
In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which the time dependence of the field is general; for example, it could be a Gaussian pulse in time. The changes that occur on transformation in the quantities that describe the wave are obtained and discussed. These changes include the temporal behaviour, direction of propagation, electromagnetic field, energy, and linear momentum. The derivation uses only elementary principles from special relativity, so it is suitable for an introductory course on the subject or a course on electrodynamics.
Yu, K. Y.; Chen, Y.; Li, J.; ...
2016-11-28
Nanocrystalline Ag, Cu, and Ni thin films and their coarse grained counterparts are patterned in this paper using focused ion beam and then irradiated by Kr ions within an electron microscope at room temperature. Irradiation induced in-plane strain of the films is measured by tracking the location of nanosized holes. The magnitude of the strain in all specimens is linearly dose-dependent and the strain rates of nanocrystalline metals are significantly greater as compared to that of the coarse grained metals. Finally, real-time microscopic observation suggests that substantial grain boundary migration and grain rotation are responsible for the significant in-plane strain.
Yu, K. Y.; Chen, Y.; Li, J.; Liu, Y.; Wang, H.; Kirk, M. A.; Li, M.; Zhang, X.
2016-11-28
Nanocrystalline Ag, Cu, and Ni thin films and their coarse grained counterparts are patterned in this paper using focused ion beam and then irradiated by Kr ions within an electron microscope at room temperature. Irradiation induced in-plane strain of the films is measured by tracking the location of nanosized holes. The magnitude of the strain in all specimens is linearly dose-dependent and the strain rates of nanocrystalline metals are significantly greater as compared to that of the coarse grained metals. Finally, real-time microscopic observation suggests that substantial grain boundary migration and grain rotation are responsible for the significant in-plane strain.
Albocher, U; Barbone, P E; Richards, M S; Oberai, A A; Harari, I
2014-01-01
We apply the adjoint weighted equation method (AWE) to the direct solution of inverse problems of incompressible plane strain elasticity. We show that based on untreated noisy displacements, the reconstruction of the shear modulus can be very poor. We link this poor performance to loss of coercivity of the weak form when treating problems with discontinuous coefficients. We demonstrate that by smoothing the displacements and appending a regularization term to the AWE formulation, a dramatic improvement in the reconstruction can be achieved. With these improvements, the advantages of the AWE method as a direct solution approach can be extended to a wider range of problems.
Albocher, U.; Barbone, P.E.; Richards, M.S.; Oberai, A.A.; Harari, I.
2014-01-01
We apply the adjoint weighted equation method (AWE) to the direct solution of inverse problems of incompressible plane strain elasticity. We show that based on untreated noisy displacements, the reconstruction of the shear modulus can be very poor. We link this poor performance to loss of coercivity of the weak form when treating problems with discontinuous coefficients. We demonstrate that by smoothing the displacements and appending a regularization term to the AWE formulation, a dramatic improvement in the reconstruction can be achieved. With these improvements, the advantages of the AWE method as a direct solution approach can be extended to a wider range of problems. PMID:25383085
NASA Technical Reports Server (NTRS)
Fisher, D. M.; Buzzard, R. J.
1979-01-01
Standard round specimen fracture test results compared satisfactorily with results from standard rectangular compact specimens machined from the same material. The location of the loading pin holes was found to provide adequate strength in the load bearing region for plane strain fracture toughness testing. Excellent agreement was found between the stress intensity coefficient values obtained from compliance measurements and the analytic solution proposed for inclusion in the standard test method. Load displacement measurements were made using long armed displacement gages and hollow loading cylinders. Gage points registered on the loading hole surfaces through small holes in the walls of the loading cylinders.
Carvalho, M.S.; Scriven, L.E.
1997-12-01
In this report the flow between rigid and a deformable rotating rolls fully submerged in a liquid pool is studied. The deformation of compliant roll cover is described by two different models (1) independent, radially oriented springs that deform in response to the traction force applied at the extremity of each or one-dimensional model, and (2) a plane-strain deformation of an incompressible Mooney-Rivlin material or non-linear elastic model. Based on the flow rate predictions of both models, an empirical relation between the spring constant of the one dimensional model and the roll cover thickness and elastic modulus is proposed.
NASA Astrophysics Data System (ADS)
Mirzana, Ishrat M.; Krishna Mohana Rao, G.; Rama Murthy, G.
2013-01-01
A rapid calculation procedure is presented for the analysis of a functionally graded tube subjected to internal pressure under plane strain condition. The exact analysis for the problem involves derivation of a hyper-geometric differential equation whose solution is a hyper-geometric function. The exact analysis involves the use of complicated terms and is time-consuming. In order to simplify the calculations, a procedure based on an approximation of variation of modulus of elasticity by an integral average value has been studied which resulted in faster calculation and results obtained have been in close agreement with exact solution highlighting the effect of material properties on stresses.
In-plane anisotropy of electrical resistivity in strain-detwinned SrFe[subscript 2]As[subscript 2
Blomberg, E.C.; Tanatar, M.A.; Kreyssig, A.; Ni, N.; Thaler, A.; Hu, Rongwei; Budko, S.L.; Canfield, P.C.; Goldman, A.I.; Prozorov, R.
2011-12-09
Intrinsic, in-plane anisotropy of electrical resistivity was studied on mechanically detwinned single crystals of SrFe{sub 2}As{sub 2} above and below the temperature of the coupled structural/magnetic transition, T{sub TO}. Resistivity is smaller for electrical current flow along the orthorhombic a{sub o} direction (direction of antiferromagnetically alternating magnetic moments) and is larger for transport along the b{sub o} direction (direction of ferromagnetic chains), which is similar to CaFe{sub 2}As{sub 2} and BaFe{sub 2}As{sub 2} compounds. A strongly first-order structural transition in SrFe{sub 2}As{sub 2} was confirmed by high-energy x-ray measurements, with the transition temperature and character unaffected by moderate strain. For small strain levels, which are just sufficient to detwin the sample, we find a negligible effect on the resistivity above T{sub TO}. With the increase of strain, the resistivity anisotropy starts to develop above T{sub TO}, clearly showing the relation of anisotropy to an anomalously strong response to strain. Our study suggests that electronic nematicity cannot be observed in the FeAs-based compounds in which the structural transition is strongly first order.
In-plane anisotropy of electrical resistivity in strain-detwinned SrFe2As2
NASA Astrophysics Data System (ADS)
Blomberg, E. C.; Tanatar, M. A.; Kreyssig, A.; Ni, N.; Thaler, A.; Hu, Rongwei; Bud'Ko, S. L.; Canfield, P. C.; Goldman, A. I.; Prozorov, R.
2011-04-01
Intrinsic, in-plane anisotropy of electrical resistivity was studied on mechanically detwinned single crystals of SrFe2As2 above and below the temperature of the coupled structural/magnetic transition, TTO. Resistivity is smaller for electrical current flow along the orthorhombic ao direction (direction of antiferromagnetically alternating magnetic moments) and is larger for transport along the bo direction (direction of ferromagnetic chains), which is similar to CaFe2As2 and BaFe2As2 compounds. A strongly first-order structural transition in SrFe2As2 was confirmed by high-energy x-ray measurements, with the transition temperature and character unaffected by moderate strain. For small strain levels, which are just sufficient to detwin the sample, we find a negligible effect on the resistivity above TTO. With the increase of strain, the resistivity anisotropy starts to develop above TTO, clearly showing the relation of anisotropy to an anomalously strong response to strain. Our study suggests that electronic nematicity cannot be observed in the FeAs-based compounds in which the structural transition is strongly first order.
Derivation of a variational principle for plane strain elastic-plastic silk biopolymers
NASA Astrophysics Data System (ADS)
He, J. H.; Liu, F. J.; Cao, J. H.; Zhang, L.
2014-01-01
Silk biopolymers, such as spider silk and Bombyx mori silk, behave always elastic-plastically. An elastic-plastic model is adopted and a variational principle for the small strain, rate plasticity problem is established by semi-inverse method. A trial Lagrangian is constructed where an unknown function is included which can be identified step by step.
GENERAL STRAIN THEORY, PERSISTENCE, AND DESISTANCE AMONG YOUNG ADULT MALES
Eitle, David
2010-01-01
Purpose Despite the surge in scholarly activity investigating the criminal career, relatively less attention has been devoted to the issue of criminal desistance versus persistence (until recently). The present study contributed to our understanding of this process by exploring the suitability of General Strain Theory (GST) for predicting changes in criminal activity across time. Methods Data from a longitudinal study of males in South Florida are examined using robust regression analyses. Results The core GST relationship, that changes in strain should predict changes in criminal activity, was supported, even after controlling for important adult social roles such as marriage, labor force participation, and education. While no support for the proposition that changes in self-esteem and social support moderate the strain-criminal desistance association was evinced, evidence was found that angry disposition, a measure of negative emotionality, moderated the association between change in chronic stressors and change in criminal activity. Conclusions While exploratory in nature, these findings demonstrate the utility of employing GST principles in studies of criminal desistance. PMID:21499526
Does the General Strain Theory Explain Gambling and Substance Use?
Greco, Romy; Curci, Antonietta
2016-11-22
General Strain Theory (GST: Agnew Criminology 30:47-87, 1992) posits that deviant behaviour results from adaptation to strain and the consequent negative emotions. Empirical research on GST has mainly focused on aggressive behaviours, while only few research studies have considered alternative manifestations of deviance, like substance use and gambling. The aim of the present study is to test the ability of GST to explain gambling behaviours and substance use. Also, the role of family in promoting the adoption of gambling and substance use as coping strategies was verified. Data from 266 families with in mean 8 observations for each group were collected. The multilevel nature of the data was verified before appropriate model construction. The clustered nature of gambling data was analysed by a two-level Hierarchical Linear Model while substance use was analysed by Multivariate Linear Model. Results confirmed the effect of strain on gambling and substance use while the positive effect of depressive emotions on these behaviours was not supported. Also, the impact of family on the individual tendency to engage in addictive behaviours was confirmed only for gambling.
The generalized scattering coefficient method for plane wave scattering in layered structures
NASA Astrophysics Data System (ADS)
Liu, Yu; Li, Chao; Wang, Huai-Yu; Zhou, Yun-Song
2017-02-01
The generalized scattering coefficient (GSC) method is pedagogically derived and employed to study the scattering of plane waves in homogeneous and inhomogeneous layered structures. The numerical stabilities and accuracies of this method and other commonly used numerical methods are discussed and compared. For homogeneous layered structures, concise scattering formulas with clear physical interpretations and strong numerical stability are obtained by introducing the GSCs. For inhomogeneous layered structures, three numerical methods are employed: the staircase approximation method, the power series expansion method, and the differential equation based on the GSCs. We investigate the accuracies and convergence behaviors of these methods by comparing their predictions to the exact results. The conclusions are as follows. The staircase approximation method has a slow convergence in spite of its simple and intuitive implementation, and a fine stratification within the inhomogeneous layer is required for obtaining accurate results. The expansion method results are sensitive to the expansion order, and the treatment becomes very complicated for relatively complex configurations, which restricts its applicability. By contrast, the GSC-based differential equation possesses a simple implementation while providing fast and accurate results.
Pârvu, A E; Ţălu, Ş; Crăciun, C; Alb, S F
2014-04-01
Fractal and multifractal analysis are useful additional non-invasive methods for quantitative description of complex morphological features. However, the quantitative and qualitative assessment of morphologic changes within human gingival cells and tissues are still unexplored. The aim of this work is to assess the structural gingival changes in patients with generalized chronic periodontitis (GCP), before and after scaling and root planing (SRP) by using fractal and multifractal analysis. Twelve adults with untreated chronic periodontitis were treated only by SRP. At baseline and after SRP, gingivomucosal biopsies were collected for histopathological examination. Fractal and multifractal analysis of digital images of the granular, spinous and basal and conjunctive layers structure, using the standard box-counting method was performed. The fractal dimension was determined for cell membrane, nuclear membrane of cell and nucleolus membrane of cell. In GCP a higher fractal dimension corresponds to a higher geometric complexity of cells contour, as its values increase when the contour irregularities increase. The generalized fractal dimensions were determined for the conjunctive layer structure of patients with GCP and patients with GCP and SRP. The fractal and multifractal analysis of gingival biopsies confirmed earlier findings that SRP reduces gingival injury in patients with GCP. It has been shown that fractal and multifractal analysis of tissue images as a non-invasive technique could be used to measure contrasting morphologic changes within human gingival cells and tissues and can provide detailed information for investigation of healthy and diseased gingival mucosa from patients with GCP. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
NASA Astrophysics Data System (ADS)
Poling, Joel; Desai, Niranjan
2017-04-01
This investigation determined the smallest strain accurately measurable by a state-of-the-art digital image correlation (DIC) - based tool used in structural health monitoring, in a specimen subjected to out-of-plane movement, building upon a study that concluded that out-of-plane specimen movement results in noise in DIC-based strain measurements. This study was motivated by initially undetected damage at low strains in connections of a real-world bridge, whose detection would have prevented its propagation, resulting in lower repair costs. The smallest strains accurately measurable using the state-of-the-art DIC tool, over a range of specimen out-of-plane displacement amplitudes, were determined.
NASA Astrophysics Data System (ADS)
Paul, H.; Tarasek, A.; Wajda, W.; Berent, K.
2014-08-01
Crystal lattice rotations induced by shear bands developed in an AA1050 aluminium alloy have been examined in order to investigate the influence of the finegrained structure on the slip propagation across the grain boundaries and the resulting texture evolution. Samples of the AA1050 alloy were pre-deformed in ECAP up to 6 passes via route C, then machined and further compressed in a channel-die up to ~25% at room temperature. The microstructure and texture were characterized by SEM equipped with a high resolution EBSD facility. The ECAP-processing leads to the formation of a fine grained structure. The grains were grouped into nearly complementarily oriented layers. During the secondary straining in the channel-die, the layers of fine grains, initially situated almost parallel to the compression plane, undergo deflection within some narrow areas. This is the beginning stage of the macroscopic shear band (MSB) formation. In all the deformed grains examined (within MSB) a strong tendency for strain-induced re-orientation could be observed. The SEM orientation mapping shows how the layers of flattened grains are incorporated into the MSB area, and what kinds of mechanisms are responsible for the strain accommodation at the macro-scale. Finally, a crystallographic description of the mechanism of MSB formation in AA1050 aluminium alloy is proposed based on the local lattice re-orientations due to localized kinking.
ERIC Educational Resources Information Center
Moon, Byongook; Morash, Merry; McCluskey, Cynthia Perez; Hwang, Hye-Won
2009-01-01
Using longitudinal data on South Korean youth, the authors addressed limitations of previous tests of general strain theory (GST), focusing on the relationships among key strains, situational- and trait-based negative emotions, conditioning factors, and delinquency. Eight types of strain previously shown most likely to result in delinquency,…
ERIC Educational Resources Information Center
Bao, Wan-Ning; Haas, Ain; Chen, Xiaojin; Pi, Yijun
2014-01-01
In Agnew's general strain theory, repeated strains can generate crime and delinquency by reducing social control and fostering social learning of crime. Using a sample of 615 middle-and high-school students in China, this study examines how social control and social learning variables mediate the effect of repeated strains in school and at home on…
ERIC Educational Resources Information Center
Bao, Wan-Ning; Haas, Ain; Chen, Xiaojin; Pi, Yijun
2014-01-01
In Agnew's general strain theory, repeated strains can generate crime and delinquency by reducing social control and fostering social learning of crime. Using a sample of 615 middle-and high-school students in China, this study examines how social control and social learning variables mediate the effect of repeated strains in school and at home on…
ERIC Educational Resources Information Center
Moon, Byongook; Morash, Merry; McCluskey, Cynthia Perez; Hwang, Hye-Won
2009-01-01
Using longitudinal data on South Korean youth, the authors addressed limitations of previous tests of general strain theory (GST), focusing on the relationships among key strains, situational- and trait-based negative emotions, conditioning factors, and delinquency. Eight types of strain previously shown most likely to result in delinquency,…
The strain in the array is mainly in the plane (waves below ~1 Hz)
Gomberg, J.; Pavlis, G.; Bodin, P.
1999-01-01
We compare geodetic and single-station methods of measuring dynamic deformations and characterize their causes in the frequency bands 0.5-1.0 Hz and 4.0-8.0 Hz. The geodetic approach utilizes data from small-aperture seismic arrays, applying techniques from geodesy. It requires relatively few assumptions and a priori information. The single-station method uses ground velocities recorded at isolated or single stations and assumes all the deformation is due to plane-wave propagation. It also requires knowledge of the azimuth and horizontal velocity of waves arriving at the recording station. Data employed come from a small-aperture, dense seismic array deployed in Geyokcha, Turkmenistan, and include seismograms recorded by broadband STS2 and short-period L28 sensors. Poor agreement between geodetic and single-station estimates in the 4.0-8.0 Hz passband indicates that the displacement field may vary nonlinearly with distance over distances of ~50 m. STS2 geodetic estimates provide a robust standard in the 0.5-1.0 Hz passband because they appear to be computationally stable and require fewer assumptions than single-station estimates. The agreement between STS2 geodetic estimates and single-station L28 estimates is surprisingly good for the S-wave and early surface waves, suggesting that the single-station analysis should be useful with commonly available data. These results indicate that, in the 0.5 to 1.0 Hz passband, the primary source of dynamic deformation is plane-wave propagation along great-circle source-receiver paths. For later arriving energy, the effects of scattering become important. The local structure beneath the array exerts a strong control on the geometry of the dynamic deformation, implying that it may be difficult to infer source characteristics of modern or paleoearthquakes from indicators of dynamic deformations. However, strong site control also suggests that the dynamic deformations may be predictable, which would be useful for engineering
NASA Astrophysics Data System (ADS)
Harikumar, M.; Sankar, N.; Chandrakaran, S.
2015-09-01
Since 1969, when the concept of earth reinforcing was brought about by Henry Vidal, a large variety of materials such as steel bars, tire shreds, polypropylene, polyester, glass fibres, coir and jute fibres etc. have been widely added to soil mass randomly or in a regular, oriented manner. The conventional reinforcements in use were two dimensional or planar, in the form of strips with negligible widths or in the form of sheets. In this investigation, a novel concept of multi oriented plastic reinforcement (hexa-pods) is discussed. Direct shear tests were conducted on unreinforced and reinforced dry fine, medium and coarse sands. Detailed parametric studies with respect to the effective grain size of soil (d10), normal stress (σ) and the volume ratio of hexa-pods (Vr) were performed. It was noticed that addition of hexa-pods resulted in increase in the shear strength parameters viz. peak deviatoric stresses and increased angle of internal friction. The hexa-pods also changed the brittle behaviour of unreinforced sand samples to ductile ones. Although the peak shear stress did not show a considerable improvement, the angle of internal friction improved noticeably. Addition of a single layer of reinforcement along the shear plane also reduced the post peak loss of strength and changed the soil behavior from brittle to a ductile one.
A generalization of Cesàro's relation for plane finite deformations
NASA Astrophysics Data System (ADS)
Chiskis, Alexander
1995-09-01
Using a new representation for the gradient of the rotation angle, the construction of a displacement field via the stretch tensor is reduced to quadrature for plane finite deformations. The compatibility equation is written in a very brief new form.
NASA Astrophysics Data System (ADS)
Skafte, Anders; Aenlle, Manuel L.; Brincker, Rune
2016-02-01
Measurement systems are being installed in more and more civil structures with the purpose of monitoring the general dynamic behavior of the structure. The instrumentation is typically done with accelerometers, where experimental frequencies and mode shapes can be identified using modal analysis and used in health monitoring algorithms. But the use of accelerometers is not suitable for all structures. Structures like wind turbine blades and wings on airplanes can be exposed to lightning, which can cause the measurement systems to fail. Structures like these are often equipped with fiber sensors measuring the in-plane deformation. This paper proposes a method in which the displacement mode shapes and responses can be predicted using only strain measurements. The method relies on the newly discovered principle of local correspondence, which states that each experimental mode can be expressed as a unique subset of finite element modes. In this paper the technique is further developed to predict the mode shapes in different states of the structure. Once an estimate of the modes is found, responses can be predicted using the superposition of the modal coordinates weighted by the mode shapes. The method is validated with experimental tests on a scaled model of a two-span bridge installed with strain gauges. Random load was applied to simulate a civil structure under operating condition, and strain mode shapes were identified using operational modal analysis.
Gerstein, Gregory; Klusemann, Benjamin; Bargmann, Swantje; Schaper, Mirko
2015-01-15
In the current work, the evolutions of grain and dislocation microstructures are investigated on the basis of plane strain tension and simple shear tests for an interstitial free steel (DC06) and a 6000 series aluminum alloy (AA6016-T4). Both materials are commonly-used materials in the automobile industry. The focus of this contribution is on the characterization and comparison of the microstructure formation in DC06 and AA6016-T4. Our observations shed light on the active mechanisms at the micro scale governing the macroscopic response. This knowledge is of great importance to understand the physical deformation mechanisms, allowing the control and design of new, tailor-made materials with the desired material behavior.
NASA Astrophysics Data System (ADS)
Graba, M.
2017-02-01
This paper provides a numerical analysis of selected parameters of fracture mechanics for double-edge notched specimens in tension, DEN(T), under plane strain conditions. The analysis was performed using the elastic-plastic material model. The study involved determining the stress distribution near the crack tip for both small and large deformations. The limit load solution was verified. The J-integral, the crack tip opening displacement, and the load line displacement were determined using the numerical method to propose the new hybrid solutions for calculating these parameters. The investigations also aimed to identify the influence of the plate geometry and the material characteristics on the parameters under consideration. This paper is a continuation of the author's previous studies and simulations in the field of elastic-plastic fracture mechanics.
Gerstein, Gregory; Klusemann, Benjamin; Bargmann, Swantje; Schaper, Mirko
2015-01-01
In the current work, the evolutions of grain and dislocation microstructures are investigated on the basis of plane strain tension and simple shear tests for an interstitial free steel (DC06) and a 6000 series aluminum alloy (AA6016-T4). Both materials are commonly-used materials in the automobile industry. The focus of this contribution is on the characterization and comparison of the microstructure formation in DC06 and AA6016-T4. Our observations shed light on the active mechanisms at the micro scale governing the macroscopic response. This knowledge is of great importance to understand the physical deformation mechanisms, allowing the control and design of new, tailor-made materials with the desired material behavior. PMID:28787938
Vibrations in a Fluid-Loaded Poroelastic Hollow Cylinder Surrounded by a Fluid in Plane-Strain Form
NASA Astrophysics Data System (ADS)
Shanker, B.; Nath, C. N.; Shah, S. A.; Reddy, P. M.
2013-03-01
Plane-strain vibrations in a fluid-loaded poroelastic hollow cylinder surrounded by a fluid are investigated employing Biot's theory of wave propagation in poroelastic media. The poroelastic hollow cylinder is homogeneous and isotropic, while the inner and outer fluids are homogeneous, isotropic and inviscid. The frequency equation of the fluid-loaded poroelastic cylinder surrounded by a fluid is obtained along with several particular cases, namely, fluid-loaded poroelastic cylinder, fluid-loaded bore, poroelastic cylinder surrounded by a fluid and poroelastic solid cylinder submerged in a fluid. The frequency equations are obtained for axially symmetric, flexural and anti-symmetric vibrations each for a pervious and an impervious surface. Nondimensional frequency for propagating modes is computed as a function of the ratio of thickness to the inner radius of the core. The results are presented graphically for two types of poroelastic cylinders and then discussed.
The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence
ERIC Educational Resources Information Center
Smith, Glenn S.
2012-01-01
In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…
The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence
ERIC Educational Resources Information Center
Smith, Glenn S.
2012-01-01
In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…
Lai, Chih-Ming; Huang, Yu-En; Feng, Shih-Wei; Kou, Kuang-Yang; Chen, Chien-Hsun; Tu, Li-Wei
2015-07-13
Anisotropic strain relaxation and the resulting degree of polarization of photoluminescence (PL) in nonpolar a-plane textured ZnO are experimentally and theoretically studied. A thicker nonpolar a-plane textured ZnO film enhances the anisotropic in-plane strain relaxation, resulting in a larger degree of polarization of PL and better sample quality. Anisotropic in-plane strains, sample quality, and degree of polarization of PL in nonpolar a-plane ZnO are consequences of the degree of anisotropic in-plane strain relaxation. By the k·p perturbation approach, simulation results of the variation of the degree of polarization for the electronic transition upon anisotropic in-plane strain relaxation agree with experimental results.
Omote, Kazuhiko
2010-12-01
We have measured the strain of a thin Si layer deposited on a SiGe layer using a high resolution x-ray diffraction system. The Si layer was deposited on the SiGe layer in order to introduce a tensile strain to the Si layer. To measure the in-plane lattice constant accurately, we have employed so-called grazing-incidence in-plane diffraction. For this measurement, we have made a new five-axis x-ray goniometer which has four ordinal circles (ω, 2θ, χ, φ) plus a counter-χ-axis for selecting the exit angle of the diffracted x-rays. In grazing-incidence geometry, an incident x-ray is focused on the sample surface in order to obtain good diffraction intensity even though the layer thickness is less than 5 nm. Because diffracted x-rays are detected through analyzer crystals, the diffraction angle can be determined with an accuracy of ± 0.0003°. This indicates that the strain sensitivity is about 10( - 5) when we measure in-plane Si 220 diffraction. Use of x-ray diffraction could be the best standard metrology method for determining strain in thin layers. Furthermore, we have demonstrated that incident/exit angle selected in-plane diffraction is very useful for height/depth selective strain determination.
A general BRDF/BSDF model including out-of-plane dependence
NASA Astrophysics Data System (ADS)
Thomas, M. E.; Joseph, R. I.; Tropf, W. J.; Brown, A. M.
2010-08-01
A semi-empirical reflectance/scatterance model has evolved over the years to represent a diverse set of materials from coated substrates to optical windows. This model separates the BRDF/BSDF into four basic components, specular, near-specular, diffuse, and Lambertian (random diffuse) terms. The specular and near-specular components employ a Gaussian phase function and the Fresnel power reflection coefficient. The Lambertian component uses Kubelka-Munk theory for the total integrated reflectance and transmittance. The model features wavelength, angle, and full hemispherical dependencies. It is applied to a variety of samples, from painted surfaces to transparent windows, with good success. This parameterized modeling approach is attractive because algorithms that use the model can be computationally efficient. Previous work has only considered in-plane effects. The present paper now explicitly takes into account the out-of-plane contribution and improves the total integrated factors.
Frenkel, A L; Indireshkumar, K
1999-10-01
Wavy film flow of incompressible Newtonian fluid down an inclined plane is considered. The question is posed as to the parametric conditions under which the description of evolution can be approximately reduced for all time to a single evolution equation for the film thickness. An unconventional perturbation approach yields the most general evolution equation and least restrictive conditions on its validity. The advantages of this equation for analytical and numerical studies of three-dimensional waves in inclined films are pointed out.
Wu, Huaping; Chai, Guozhong; Zhou, Ting; Zhang, Zheng; Kitamura, Takayuki; Zhou, Haomiao
2014-03-21
The strain-mediated magnetoelectric (ME) property of self-assembled vertical multiferroic nanocomposite films epitaxially grown on cubic substrates was calculated by a nonlinear thermodynamic theory combined with the elastic theory. The dependent relations of phase state of ferroelectric films with the in-plane misfit strain, out-of-plane misfit strain, temperature, and volume fraction of ferromagnetic phase were confirmed. The effects of in-plane misfit strain and ferromagnetic volume fraction on the polarization and dielectric constant of ferroelectric films at room temperature were elaborately analyzed for the vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films. Our calculated results confirmed the relationship among ME effect and in-plane misfit strain and ferromagnetic volume fraction in the nanocomposite films. The ME voltage coefficients of vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films displayed various maximums and abrupt points at special phases and phase transition boundaries. The ME voltage coefficients of lead-free BaTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films epitaxially grown on different substrates could reach a comparative value of ∼2 V·cm{sup −1}·Oe{sup −1} under the controllable in-plane misfit strain induced by substrate clamping. Our results provided an available method for the optimal design of vertical multiferroic nanocomposites with adjustable ME effect by optimizing the ferromagnetic volume fraction and substrate type.
ERIC Educational Resources Information Center
Moon, Byongook; Morash, Merry
2017-01-01
The present study of 659 Korean adolescents tests General Strain Theory's (GST) utility in explaining gender differences in delinquency causation. It models the effects of key strains, negative emotions, and a composite measure of several conditioning factors separately for boys and girls and for delinquency. Consistent with the theory, males and…
General scaling limitations of ground-plane and isolated-object cloaks
Hashemi, Hila; Johnson, Steven G.; Oskooi, A.; Joannopoulos, J. D.
2011-08-15
We prove that, for arbitrary three-dimensional transformation-based invisibility cloaking of an object above a ground plane or of isolated objects, there are practical constraints that increase with the object size. In particular, we show that the cloak thickness must scale proportionally to the thickness of the object being cloaked, assuming bounded refractive indices, and that absorption discrepancies and other imperfections must scale inversely with the object thickness. For isolated objects, we also show that bounded refractive indices imply a lower bound on the effective cross section.
ERIC Educational Resources Information Center
Moon, Byongook; Blurton, David; McCluskey, John D.
2008-01-01
The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…
NASA Astrophysics Data System (ADS)
Nakashima, Takaaki; Ichinose, Daichi; Ehara, Yoshitaka; Shimizu, Takao; Kobayashi, Takeshi; Yamada, Tomoaki; Funakubo, Hiroshi
2017-03-01
(100)/(001)-oriented epitaxial lead titanate (PbTiO3) films with various thicknesses were grown on (100) KTaO3 substrates by pulsed metal-organic chemical vapor deposition. The change of crystal structure with film thickness and deposition temperature was investigated. The paraelectric phase of 50 and 1000 nm-thick films had a tensile strain of 0.5% and almost 0% at 700 °C, respectively. The phase change temperature from the paraelectric phase to the ferroelectric phase, the Curie temperature (Tc), increased with the in-plane strain of the paraelectric phase; that is, Tc increased with decreasing film thickness. In contrast, room-temperature tetragonal distortion decreased as the film became thinner. This study reveals the effect of in-plane tensile strain in (100)/(001)-oriented epitaxial PbTiO3 films with higher Tc and smaller tetragonal distortion at room temperature.
NASA Astrophysics Data System (ADS)
Hu, Lun-Hui; Xu, Dong-Hui; Zhang, Fu-Chun; Zhou, Yi
2016-08-01
Motivated by the recent discovery of quantized spin Hall effect in InAs/GaSb quantum wells [Du, Knez, Sullivan, and Du, Phys. Rev. Lett. 114, 096802 (2015), 10.1103/PhysRevLett.114.096802], we theoretically study the effects of in-plane magnetic field and strain effect to the quantization of charge conductance by using Landauer-B ütikker formalism. Our theory predicts a robustness of the conductance quantization against the in-plane magnetic field up to a very high field of 20 T. We use a disordered hopping term to model the strain and show that the strain may help the quantization of the conductance. Relevance to the experiments will be discussed.
Linear stability of plane Poiseuille flow over a generalized Stokes layer
NASA Astrophysics Data System (ADS)
Quadrio, Maurizio; Martinelli, Fulvio; Schmid, Peter J.
2011-12-01
Linear stability of plane Poiseuille flow subject to spanwise velocity forcing applied at the wall is studied. The forcing is stationary and sinusoidally distributed along the streamwise direction. The long-term aim of the study is to explore a possible relationship between the modification induced by the wall forcing to the stability characteristic of the unforced Poiseuille flow and the signifcant capabilities demonstrated by the same forcing in reducing turbulent friction drag. We present in this paper the statement of the mathematical problem, which is considerably more complex that the classic Orr-Sommerfeld-Squire approach, owing to the streamwise-varying boundary condition. We also report some preliminary results which, although not yet conclusive, describe the effects of the wall forcing on modal and non-modal characteristics of the flow stability.
Li, Hong; Tsai, Charlie; Koh, Ai Leen; Cai, Lili; Contryman, Alex W.; Fragapane, Alex H.; Zhao, Jiheng; Han, Hyun Soon; Manoharan, Hari C.; Abild-Pedersen, Frank; Nørskov, Jens K.; Zheng, Xiaolin
2015-11-09
As a promising non-precious catalyst for the hydrogen evolution reaction, molybdenum disulphide (MoS_{2}) is known to contain active edge sites and an inert basal plane. Activating the MoS_{2} basal plane could further enhance its HER activity but is not often a strategy for doing so. Herein, we report the first activation and optimization of the basal plane of monolayer 2H-MoS_{2} for HER by introducing sulphur (S) vacancies and strain. Our theoretical and experimental results show that the S-vacancies are new catalytic sites in the basal plane, where gap states around the Fermi level allow hydrogen to bind directly to exposed Mo atoms. The hydrogen adsorption free energy (ΔG_{H}) can be further manipulated by straining the surface with S-vacancies, which fine-tunes the catalytic activity. Furthermore, proper combinations of S-vacancy and strain yield the optimal ΔG_{H} = 0 eV, which allows us to achieve the highest intrinsic HER activity among molybdenum-sulphide-based catalysts.
NASA Astrophysics Data System (ADS)
Reza Barati, Mohammad
2017-09-01
For the first time, a vibrating porous double-nanoplate system under in-plane periodic loads is modeled via the generalized nonlocal strain gradient theory (NSGT). Based on the proposed theory, one can examine both stiffness-softening and stiffness-hardening effects for a more accurate analysis of nanoplates. Nanopores or nanovoids are incorporated to the model based on a modified rule of mixture. Modeling of porous double-layered nanoplate is conducted according to a refined four-variable plate theory with fewer field variables than first-order plate theory. The governing equations and related classical and nonclassical boundary conditions are derived based on Hamilton's principle. These equations are solved for hinged nanoplates via Galerkin's method. It is shown that porosities, nonlocal parameter, strain gradient parameter, material gradation, interlayer stiffness, elastic foundation, side-to-thickness and aspect ratios have a notable impact on the vibration behavior of nanoporous materials.
Generalization of strain-gradient theory to finite elastic deformation for isotropic materials
NASA Astrophysics Data System (ADS)
Beheshti, Alireza
2017-03-01
This paper concerns finite deformation in the strain-gradient continuum. In order to take account of the geometric nonlinearity, the original strain-gradient theory which is based on the infinitesimal strain tensor is rewritten given the Green-Lagrange strain tensor. Following introducing the generalized isotropic Saint Venant-Kirchhoff material model for the strain-gradient elasticity, the boundary value problem is investigated in not only the material configuration but also the spatial configuration building upon the principle of virtual work for a three-dimensional solid. By presenting one example, the convergence of the strain-gradient and classical theories is studied.
Towards a generalized iso-density continuum model for molecular solvents in plane-wave DFT
NASA Astrophysics Data System (ADS)
Gunceler, Deniz; Arias, T. A.
2017-01-01
Implicit electron-density solvation models offer a computationally efficient solution to the problem of calculating thermodynamic quantities of solvated systems from first-principles quantum mechanics. However, despite much recent interest in such models, to date the applicability of such models in the plane-wave context to non-aqueous solvents has been limited because the determination of the model parameters requires fitting to a large database of experimental solvation energies for each new solvent considered. This work presents a simple approach to quickly find approximations to the non-electrostatic contributions to the solvation energy, allowing for development of new iso-density models for a large class of protic and aprotic solvents from only simple, single-molecule ab initio calculations and readily available bulk thermodynamic data. Finally, to illustrate the capabilities of the resulting theory, we also calculate the surface solvation energies of crystalline LiF in various different non-aqueous solvents, and discuss the observed trends and their relevance to lithium battery technology.
A general method for the existence of periodic solutions of differential systems in the plane
NASA Astrophysics Data System (ADS)
Fonda, Alessandro; Sfecci, Andrea
We propose a general method to prove the existence of periodic solutions for planar systems of ordinary differential equations, which can be used in many different circumstances. Applications are given to some nonresonant cases, even for systems with superlinear growth in some direction, or with a singularity. Systems "at resonance" are also considered, provided a Landesman-Lazer type of condition is assumed.
Domain structure and in-plane switching in a highly strained Bi0.9Sm0.1FeO3 film
NASA Astrophysics Data System (ADS)
Chen, Weigang; Ren, Wei; You, Lu; Yang, Yurong; Chen, Zuhuang; Qi, Yajun; Zou, Xi; Wang, Junling; Sritharan, Thirumany; Yang, Ping; Bellaiche, L.; Chen, Lang
2011-11-01
We report the domain structure and ferroelectric properties of a 32 nm-thick Bi0.9Sm0.1FeO3 film epitaxially grown on a LaAlO3 (LAO) substrate. This film exhibits a monoclinic Mc phase, with its monoclinic distortion and anisotropy of in-plane (IP) lattice parameters being both smaller than those of pure BiFeO3 (BFO) grown on LaAlO3. Polarization hysteresis loops measured using a quasi-planar capacitor show an in-plane polarization up to 30 μC/cm2. Piezoresponse force microcopy demonstrates that a 180° in-plane polarization switching accompanied by a 90° domain wall rotation takes place after electric poling. First-principles calculations suggest the differences between highly strained Sm-substituted and pure BiFeO3.
NASA Astrophysics Data System (ADS)
Qiao, Liang; Bi, Xiaofang
2008-02-01
Highly (001)-textured BaTiO3 films were grown epitaxially on the LaNiO3 buffered Si substrate. A strong in-plane tensile strain has been revealed by using x-ray diffraction and high resolution transmission electron microscopy. The BaTiO3 film has exhibited a small remnant polarization, indicating the presence of ca1/ca2/ca1/ca2 polydomain state in the film. Temperature dependent dielectric permittivity has demonstrated that two phase transitions occurred at respective temperatures of 170 and 30°C. The result was discussed in detail based on the misfit strain-temperature phase diagrams theory.
Camasso, M J; Jagannathan, R
2001-01-01
This study employed stated preference (SP) models to determine why general aviation pilots choose to base and operate their aircraft at some airports and not others. Thirteen decision variables identified in pilot focus groups and in the general aviation literature were incorporated into a series of hypothetical choice tasks or scenarios. The scenarios were offered within a fractional factorial design to establish orthogonality and to preclude dominance in any combination of variables. Data from 113 pilots were analyzed for individual differences across pilots using conditional logit regression with and without controls. The results demonstrate that some airport attributes (e.g., full-range hospitality services, paved parallel taxiway, and specific types of runway lighting and landing aids) increase pilot utility. Heavy airport congestion and airport landing fees, on the other hand, decrease pilot utility. The importance of SP methodology as a vehicle for modeling choice behavior and as an input into the planning and prioritization process is discussed. Actual or potential applications include the development of structured decision-making instruments in the behavioral sciences and in human service programs.
NASA Astrophysics Data System (ADS)
Qiu, J. H.; Jiang, Q.
2007-02-01
A phenomenological Landau-Devonshine theory is used to describe the effects of external mechanical loading on equilibrium polarization states and dielectric properties in epitaxial ferroelectric thin films grown on dissimilar orthorhombic substrates which induce anisotropic misfit strains in the film plane. The calculation focuses on single-domain perovskite BaTiO3 and PbTiO3 thin films on the assumption that um1=-um2. Compared with the phase diagrams without external loading, the characteristic features of "misfit strain-misfit strain" phase diagrams at room temperature are the presence of paraelectric phase and the strain-induced ferroelectric to paraelectric phase transition. Due to the external loading, the "misfit strain-stress" and "stress-temperature" phase diagrams also have drastic changes, especially for the vanishing of paraelectric phase in "misfit strain-stress" phase map and the appearance of possible ferroelectric phases. We also investigate the dielectric properties and the tunability of both BaTiO3 and PbTiO3 thin films. We find that the external stress dependence of phase diagrams and dielectric properties largely depends on strain anisotropy as well.
ERIC Educational Resources Information Center
Ellwanger, Steven J.
2007-01-01
This article enhances our knowledge of general strain theory (GST) by applying it to the context of traffic delinquency. It does so by first describing and confirming the development of a social-psychological measure allowing for a test of GST. Structural regression analysis is subsequently employed to test the theory within this context across a…
NASA Astrophysics Data System (ADS)
Xu, Feng; Davis, Anthony B.; Diner, David J.
2016-11-01
A Markov chain formalism is developed for computing the transport of polarized radiation according to Generalized Radiative Transfer (GRT) theory, which was developed recently to account for unresolved random fluctuations of scattering particle density and can also be applied to unresolved spectral variability of gaseous absorption as an improvement over the standard correlated-k method. Using Gamma distribution to describe the probability density function of the extinction or absorption coefficient, a shape parameter a that quantifies the variability is introduced, defined as the mean extinction or absorption coefficient squared divided by its variance. It controls the decay rate of a power-law transmission that replaces the usual exponential Beer-Lambert-Bouguer law. Exponential transmission, hence classic RT, is recovered when a→∞. The new approach is verified to high accuracy against numerical benchmark results obtained with a custom Monte Carlo method. For a<∞, angular reciprocity is violated to a degree that increases with the spatial variability, as observed for finite portions of real-world cloudy scenes. While the degree of linear polarization in liquid water cloudbows, supernumerary bows, and glories is affected by spatial heterogeneity, the positions in scattering angle of these features are relatively unchanged. As a result, a single-scattering model based on the assumption of subpixel homogeneity can still be used to derive droplet size distributions from polarimetric measurements of extended stratocumulus clouds.
NASA Astrophysics Data System (ADS)
Nam, Yoon Sung; Lee, Sang Wook; Baek, K. S.; Chang, S. K.; Song, Jae-Ho; Song, Jung-Hoon; Han, Seok Kyu; Hong, Soon-Ku; Yao, Takafumi
2008-05-01
We have investigated the polarization dependence of the near-band-edge photoluminescence and photoreflectance spectra in nonpolar (A-plane) ZnO films under strong biaxial compressive strain. We show that anisotropic strain and the orientation of the nonpolar plane play an important role in determining the polarization selectivity and properties of excitonic transitions. We identified four distinct band-edge transitions at 3.449, 3.420, 3.386, and 3.326eV. They were identified as E2 and E1 free excitons, E1 excitons bound to a donor, and free-electron-to-bound-hole transition, respectively. Unlike previously reported results on relatively thick nonpolar films, the E1 exciton (lowest energy) was mainly polarized to E ⊥c and weakly polarized to E ∥c under strong biaxial compressive strain in the 100nm thick film. The E2 exciton (next higher energy) was exclusively polarized to E ∥c. The localization energy of DX is 34meV, which is much larger than that in polar ZnO, and the DX was not thermally delocalized even at room temperature.
Feng, Shih-Wei Chen, Yu-Yu; Lai, Chih-Ming; Tu, Li-Wei; Han, Jung
2013-12-21
Anisotropic strain relaxation and the resulting degree of polarization of the electronic transition in nonpolar a-plane GaN using one- and two-step growth are studied. By using two-step growth, a slower coalescence and a longer roughening-recovery process lead to larger anisotropic strain relaxation, a less striated surface, and lower densities of basal stacking fault (BSF) and prismatic stacking fault (PSF). It is suggested that anisotropic in-plane strains, surface striation, and BSF and PSF densities in nonpolar a-GaN are consequences of the rate of coalescence, the period of roughening-recovery process, and the degree of anisotropic strain relaxation. In addition, the two-step growth mode can enhance the degree of polarization of the electronic transition. The simulation results of the k⋅p perturbation approach show that the oscillator strength and degree of polarization of the electronic transition strongly depend on the in-plane strains upon anisotropic in-plane strain relaxation. The research results provide important information for optimized growth of nonpolar III-nitrides. By using two-step growth and by fabricating the devices on the high-quality nonpolar free-standing GaN substrates, high-efficiency nonpolar a-plane InGaN LEDs can be realized. Nonpolar a-plane InGaN/GaN LEDs can exhibit a strongly polarized light to improve the contrast, glare, eye discomfort and eye strain, and efficiency in display application.
Structure and switching of in-plane ferroelectric nano-domains in strained PbxSr1-xTiO3 thin films
Matzen, Sylivia; Nesterov, Okeksiy; Rispens, Gregory; Heuver, J. A.; Bark, C; Biegalski, Michael D; Christen, Hans M; Noheda, Beatriz
2014-01-01
Nanoscale ferroelectrics, the active elements of a variety of nanoelectronic devices, develop denser and richer domain structures than the bulk counterparts. With shrinking device sizes understanding and controlling domain formation in nanoferroelectrics is being intensely studied. Here we show that a precise control of the epitaxy and the strain allows stabilizing a hierarchical domain architecture in PbxSr1-xTiO3 thin films, showing periodic, purely in-plane polarized, ferroelectric nano-domains that can be switched by a scanning probe.
NASA Astrophysics Data System (ADS)
Graber, James
2017-01-01
Results from ongoing efforts to measure the black hole shadows expected from Sgr A* and M87, e.g. by the Event-Horizon Telescope, could soon confirm or refute the Kerr nature of the black-hole shadow, thereby helping confirm or refute General Relativity. It is fairly easy to precisely calculate the width of the shadow of a compact, cylindrically symmetric rotating object in its equatorial plane. We have calculated these shadow widths for three different metrics: 1) the standard Kerr metric, 2) a rotating perturbed Kerr object with a quadrupole moment similar to a neutron star's, as computed by Frutos-Alfaro based on the earlier Manko et al. neutron-star metric, and 3) also for a new rotating metric based on the Yilmaz exponential metric. For reasonable (plausible) parameter values, the differences in calculated shadow widths are of the order of ten percent, which may be difficult to measure. We graphically present comparisons between the expected Kerr value for the shadow width, and the widths computed for the alternative metrics as a numerically computed function of the rotation and the quadrupole moment. If time allows, we may present similar calculations and graphs for the shadow widths of rotating compact objects from other alternative theories of gravity.
NASA Astrophysics Data System (ADS)
Ren, Zhenhua; Zeng, Xiantao; Liu, Hanlong; Zhou, Fengjun
2013-03-01
The application of fiber reinforced plastic (FRP), including carbon FRP and glass FRP, for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement (EBR) and near-surface mounted (NSM) strengthening techniques. This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods, including externally-bonded and near-surface mounted FRP, to study the strain coordination of the FRP and steel rebar of the RC beam. Since there is relative slipping between the RC beam and the FRP, the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis; that is, the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height ( h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of the FRP and steel rebar satisfies the equation: ɛ FRP= βɛ steel, and the value of β is equal to 1.1-1.3 according to the test results.
NASA Astrophysics Data System (ADS)
Park, Seoung-Hwan
2017-09-01
Optical gain characteristics of a-plane (11 2 bar 0) AlGaN/GaN quantum well (QW) lasers grown on a GaN buffer with strain anisotropy using a strain-engineered MgZnO layer were investigated using the multiband effective mass theory. The calculated transition energies for QW structures grown on MgZnO layer are in good agreement with experimental results. The optical gain of the QW structure grown on the MgZnO substrate is dominated by the z ‧ -polarization because the dominant states constituting the topmost valence subband for the QW structure changes from | Y ‧ > - to | Z ‧ > -like and carriers occupy higher states above k∥ = 0 at a higher carrier density. On the other hand, the optical gain of the QW structure grown on conventional GaN buffer is dominated by both y ‧ - and z ‧ -polarizations. Thus, the optical polarization characteristics of a-plane AlGaN/GaN QW lasers can be engineered by using MgZnO substrate.
Lagattu, Fabienne . E-mail: lagattu@lmpm.ensma.fr; Bridier, Florent; Villechaise, Patrick; Brillaud, Jean
2006-01-15
The purpose of this paper is to present a method based on the correlation of digital images obtained on a microscopic scale. A specific grainy pattern has been developed. The use of the scanning electron microscopy (SEM) allowed the determination of full-field 2D displacements on an object surface with a spatial resolution of about 1 {mu}m. Validation tests were performed in order to quantify performances and limits of this method. An example of its application is presented for a Ti-6Al-4V titanium alloy. Results show that it is possible to obtain in-plane displacement values on the object surface with efficient spatial resolution and accuracy. Thus, such a technique can be used to highlight on a relevant scale the role of the microstructure in material deformation processes.
Strain effects on in-plane conductance of the topological insulator Bi{sub 2}Te{sub 3}
Heui Hwang, Jin; Kwon, Sangku; Hun Kim, Jong; Young Park, Jeong; Park, Joonbum; Sung Kim, Jun; Lee, Jhinhwan; Lyeo, Ho-Ki
2014-04-21
We investigated the correlation between electrical transport and mechanical stress in a topological insulator, Bi{sub 2}Te{sub 3}, using conductive probe atomic force microscopy in an ultrahigh vacuum environment. After directly measuring charge transport on the cleaved Bi{sub 2}Te{sub 3} surface, we found that the current density varied with applied load. Current mapping revealed a variation of the current on different terraces. The current density increased in the low-pressure regime and then decreased in the high-pressure regime. This variation of current density was explained in light of the combined effect of changes in the in-plane conductance due to spin–orbit coupling and hexagonal warping.
Yang, Nicholas H; Canavan, Paul K; Nayeb-Hashemi, Hamid
2010-11-01
Subject-specific models were developed and finite element analysis was performed to observe the effect of the frontal plane tibiofemoral angle on the normal stress, Tresca shear stress and normal strain at the surface of the knee cartilage. Finite element models were created for three subjects with different tibiofemoral angle and physiological loading conditions were defined from motion analysis and muscle force mathematical models to simulate static single-leg stance. The results showed that the greatest magnitude of the normal stress, Tresca shear stress and normal strain at the medial compartment was for the varus aligned individual. Considering the lateral knee compartment, the individual with valgus alignment had the largest stress and strain at the cartilage. The present investigation is the first known attempt to analyze the effects of tibiofemoral alignment during single-leg support on the contact variables of the cartilage at the knee joint. The method could be potentially used to help identify individuals most susceptible to osteoarthritis and to prescribe preventive measures.
General Strain Theory and Delinquency: Extending a Popular Explanation to American Indian Youth
ERIC Educational Resources Information Center
Eitle, David; Eitle, Tamela McNulty
2016-01-01
Despite evidence that American Indian (AI) adolescents are disproportionately involved in crime and delinquent behavior, there exists scant research exploring the correlates of crime among this group. We posit that Agnew's General Strain Theory (GST) is well suited to explain AI delinquent activity. Using the National Longitudinal Study of…
General Strain Theory and Delinquency: Extending a Popular Explanation to American Indian Youth
ERIC Educational Resources Information Center
Eitle, David; Eitle, Tamela McNulty
2016-01-01
Despite evidence that American Indian (AI) adolescents are disproportionately involved in crime and delinquent behavior, there exists scant research exploring the correlates of crime among this group. We posit that Agnew's General Strain Theory (GST) is well suited to explain AI delinquent activity. Using the National Longitudinal Study of…
General Strain Theory as a Basis for the Design of School Interventions
ERIC Educational Resources Information Center
Moon, Byongook; Morash, Merry
2013-01-01
The research described in this article applies general strain theory to identify possible points of intervention for reducing delinquency of students in two middle schools. Data were collected from 296 youths, and separate negative binomial regression analyses were used to identify predictors of violent, property, and status delinquency. Emotional…
NASA Astrophysics Data System (ADS)
Tanuma, Ryohei; Mori, Daisuke; Kamata, Isaho; Tsuchida, Hidekazu
2012-06-01
This paper demonstrates the X-ray microbeam three-dimensional (3D) topography of basal-plane dislocations (BPDs) and threading edge dislocations (TEDs) in 4H-SiC. Stereographic images showing the propagation of BPDs from a substrate to an epilayer and the conversion of BPDs into TEDs near the epilayer/substrate interface are successfully obtained. The narrowing of BPD images is observed just before the BPD-TED conversion points. The images of effective misorientations Δω provide a spatial resolution of 1-2 µm for a TED, and the range of Δω corresponds to strains on the order of +/-10-5. We also discuss the image-formation mechanism in 3D topography.
Ma, R.; Negahban, M.
1995-12-31
The objective of this study is to investigate the effect of crystallization on the mechanical response of a polymer containing a rigid cylindrical inclusion under different loading conditions and under the plane strain restriction. As will be shown, external loading and crystallization can both induce an inhomogeneous distribution of stress and deformation in the vicinity of a cylindrical inclusion and can also interact with each other. Crystallization is a process of transition of the polymer`s microstructure from disordered state to an ordered one. This transition occurs in many polymers, such as polyethylene, polypropylene, nylon, and natural rubber. The process of crystallization gives rise to a macroscopic deformation, reducing the macroscopic volume, and it can increase the toughness and rigidity of a polymer. For example, for natural rubber crystallization causes a two order of magnitude increase in the elastic moduli. Moreover, crystallization can result in stress relaxation under constant uniaxial extension and creep under constant load. These effects have been captured in a constitutive model developed by Negahban, Wineman and Ma, which has been shown to be in good agreement with experimental results. This presentation provides (1) a theoretical evaluation of the effect of crystallization on the distribution of stress and mechanical moduli under axisymmetric loading and an estimation of the idual stress resulting from crystallization in the vicinity of a cylindrical inclusion; and (2) a numerical simulation of the stress distribution in the vicinity of an inclusion due to crystallization under both constant displacement loading and constant traction loading. All results are for plane strain conditions. Results show that an inhomogeneous distribution of stress and deformation is developed in the vicinity of the inclusion due to the external loading and/or due to crystallization.
Zhao, Guijuan; Li, Huijie; Wang, Lianshan; Meng, Yulin; Ji, Zesheng; Li, Fangzheng; Wei, Hongyuan; Yang, Shaoyan; Wang, Zhanguo
2017-07-03
In this study, the indium composition x as well as the anisotropically biaxial strain in non-polar a-plane In x Ga1-x N on GaN is studied by X-ray diffraction (XRD) analysis. In accordance with XRD reciprocal lattice space mapping, with increasing indium composition, the maximum of the In x Ga1-x N reciprocal lattice points progressively shifts from a fully compressive strained to a fully relaxed position, then to reversed tensile strained. To fully understand the strain in the ternary alloy layers, it is helpful to grow high-quality device structures using a-plane nitrides. As the layer thickness increases, the strain of In x Ga1-x N layer releases through surface roughening and the 3D growth-mode.
NASA Astrophysics Data System (ADS)
Mathew, Nithin; Sewell, Thomas D.
2015-02-01
Molecular dynamics and molecular statics simulations were used to investigate dislocation glide in the basal plane (i.e. the ?-? plane, where ?, ? and ? define the edge vectors of the unit cell) of ?-triamino-?-trinitrobenzene (TATB) using generalized stacking fault energy surfaces (?-surfaces). Triclinic symmetry and molecular packing arrangement result in two glide plane types for the same glide plane normal. The unstable stacking fault energies (?) are less than ?? at ? K and ? atm, indicating easy dislocation glide. Glide in the ? and ?-? directions is preferred compared to the ? direction at ? atm. A stable stacking fault is predicted in the ?-? direction at ? atm and 5 GPa. A compound twin with energy ?? is predicted to be stable in the basal plane. Unequal values of ? about the stable stacking fault in the ? and ?-? traces indicate an asymmetric barrier to dislocation glide. High pressure (? GPa) results in an increase in the ? values. The extremely small barriers to twinning and dislocation glide might be sources for observed second-harmonic generation in the nominally centrosymmetric crystal.
NASA Astrophysics Data System (ADS)
Sainath, Kamalesh; Teixeira, Fernando L.; Donderici, Burkay
2014-07-01
We propose the complex-plane generalization of a powerful algebraic sequence acceleration algorithm, the method of weighted averages (MWA), to guarantee exponential-cum-algebraic convergence of Fourier and Fourier-Hankel (F-H) integral transforms. This “complex-plane” MWA, effected via a linear-path detour in the complex plane, results in rapid, absolute convergence of field and potential solutions in multi-layered environments regardless of the source-observer geometry and anisotropy/loss of the media present. In this work, we first introduce a new integration path used to evaluate the field contribution arising from the radiation spectra. Subsequently, we (1) exhibit the foundational relations behind the complex-plane extension to a general Levin-type sequence convergence accelerator, (2) specialize this analysis to one member of the Levin transform family (the MWA), (3) address and circumvent restrictions, arising for two-dimensional integrals associated with wave dynamics problems, through minimal complex-plane detour restrictions and a novel partition of the integration domain, (4) develop and compare two formulations based on standard/real-axis MWA variants, and (5) present validation results and convergence characteristics for one of these two formulations.
Sainath, Kamalesh; Teixeira, Fernando L.; Donderici, Burkay
2014-07-15
We propose the complex-plane generalization of a powerful algebraic sequence acceleration algorithm, the method of weighted averages (MWA), to guarantee exponential-cum-algebraic convergence of Fourier and Fourier–Hankel (F–H) integral transforms. This “complex-plane” MWA, effected via a linear-path detour in the complex plane, results in rapid, absolute convergence of field and potential solutions in multi-layered environments regardless of the source-observer geometry and anisotropy/loss of the media present. In this work, we first introduce a new integration path used to evaluate the field contribution arising from the radiation spectra. Subsequently, we (1) exhibit the foundational relations behind the complex-plane extension to a general Levin-type sequence convergence accelerator, (2) specialize this analysis to one member of the Levin transform family (the MWA), (3) address and circumvent restrictions, arising for two-dimensional integrals associated with wave dynamics problems, through minimal complex-plane detour restrictions and a novel partition of the integration domain, (4) develop and compare two formulations based on standard/real-axis MWA variants, and (5) present validation results and convergence characteristics for one of these two formulations.
NASA Astrophysics Data System (ADS)
Wu, Xiao-Gang; Yu, Wei-Lun; Cen, Hai-Peng; Wang, Yan-Qin; Guo, Yuan; Chen, Wei-Yi
2015-02-01
A hierarchical model is developed to predict the streaming potential (SP) in the canaliculi of a loaded osteon. Canaliculi are assumed to run straight across the osteon annular cylinder wall, while disregarding the effect of lacuna. SP is generalized by the canalicular fluid flow. Analytical solutions are obtained for the canalicular fluid velocity, pressure, and SP. Results demonstrate that SP amplitude (SPA) is proportional to the pressure difference, strain amplitude, frequency, and strain rate amplitude. However, the key loading factor governing SP is the strain rate, which is a representative loading parameter under the specific physiological state. Moreover, SPA is independent of canalicular length. This model links external loads to the canalicular fluid pressure, velocity, and SP, which can facilitate further understanding of the mechanotransduction and electromechanotransduction mechanisms of bones.
Job strain and heart rate variability in resident physicians within a general hospital.
Hernández-Gaytan, Sendy Isarel; Rothenberg, Stephen J; Landsbergis, Paul; Becerril, Leonor Cedillo; De León-León, Guillermo; Collins, Sean M; Díaz-Vásquez, Francisco Javier
2013-01-01
To evaluate the association of heart rate variability with job strain in first year resident physicians. We performed the study at the "Manuel Gea González" General Hospital in Mexico City. 54 resident doctors were studied over a period of 24 hr in their first year of specialization. Two questionnaires were administered: the first on general demographics, and the second, the Job Content Questionnaire. Heart rate variability was evaluated through the frequency domain (low-frequency power, high-frequency power, and low-frequency power/high-frequency power ratio) and time domain (SDNN). The doctors wore a Holter monitor over a 24-hr period, which included a workday plus their on-call time. They recorded their activities in a log. Compared to physicians in the "low strain" category, physicians working in the "passive" category had lower overall peak-to-peak cardiac variability (standard deviation of N-N intervals, SDNN), -9.08% (95% CI -17.97, 0.74), a -25% (95% CI -45.00, 0.22) lower high-frequency power, and -26.95% (95% CI -39.00, -12.53) lower low-frequency power. Physicians working in the "high strain" category had lower low-frequency power, -17.85% (95%CI -32.34, -0.25), and lower low-frequency/high-frequency ratio -24.29% (95% CI 38.08, 7.42) compared to those in the "low strain" category. High job strain and low job control among medical residents were associated with several indicators of lowered heart rate variability. Thus, analysis of heart rate variability may be an informative marker for evaluating the physiological impacts of workplace stressors. Copyright © 2012 Wiley Periodicals, Inc.
van Kessel, Marco; Seaton, David; Chan, Jonathan; Yamada, Akira; Kermeen, Fiona; Butler, Thomas; Sabapathy, Surendran; Morris, Norman
2016-06-01
Pulmonary hypertension (PH) is a progressively fatal disease having a significant impact on right ventricular (RV) function, a major determinant of long-term outcome in PH patients. In our clinic we frequently noticed the combination of PH and reduced RV function, but with discordant Tricuspid Annular Plane Systolic Excursion (TAPSE) values. The present study focuses on whether RV free wall strain measured using 2-dimensional speckle-tracking echocardiography is able to predict mortality in this subgroup of PH patients. 57 patients with PH and RV dysfunction (visual echocardiographic assessment of ≥2) and pseudo-normalized TAPSE values (defined as ≥16 mm) were retrospectively evaluated. Patients were divided by RV free -20 % as cut-off value. Follow-up data on all-cause mortality were registered after a median follow-up time of 27.9 ± 1.7 months. RV free of ≥-20 % was predictive of all-cause mortality after a median follow-up time of 27.9 ± 1.7 months (HR 3.76, 95 % CI 1.02-13.92, p = 0.05). RV free ≥-20 % remained a significant predictor of all-cause mortality (HR 4.30, 95 % CI 1.11-16.61, p = 0.04) after adjusting for PH-specific treatment. On the contrary, TAPSE was not a significant predictor of all-cause mortality. RV free wall strain provides prognostic information in patients with PH and RV dysfunction, but with normal TAPSE values. Future studies with larger cohorts, longer follow-up periods and inclusion of more echocardiographic parameters measuring LV and RV function could confirm the strength of RV free ≥-20 % as a predictor of mortality for this subgroup of patients with PH.
Hans, Suruchi; Mali, Amita M.
2012-01-01
Background: Osteopontin (OPN) is a bone matrix derivative, whose levels reflect active lesions of aggravated periodontal disease accompanied by alveolar bone resorption. OPN is also a component of human atherosclerotic plaque, suggesting a role of OPN in cardiovascular diseases. The present study was conducted to assess and compare plasma OPN levels in subjects with healthy periodontium and generalized chronic periodontitis and to evaluate the effect of scaling and root planing on Plasma OPN levels of generalized chronic periodontitis subjects. Materials and Methods: 40 gender matched subjects were divided into two equal groups, Group I- Healthy and Group II- Generalized chronic periodontitis, based on the Periodontal Disease Index. Blood samples were collected from the subjects at the time of clinical examination (Group I, II) and two months after Scaling and Root planning of Group II. Plasma OPN level was determined using a OPN Enzyme Immunometric Assay Kit (Quantikine). Results: The mean value of plasma OPN levels in subjects with generalized chronic periodontitis was higher (153.08 ng/ml) as compared to the subjects with Healthy periodontium (55.09 ng/ml). After treatment of generalized chronic periodontitis group, the level of plasma OPN decreased to 91.53 ng/ml. Conclusion: The findings from the study suggest that Plasma OPN levels were highest in plasma from sites with periodontal destruction; however, scaling and root planing resulted in the reduction of OPN levels. PMID:23162328
Hrabovský, Miroslav
2014-01-01
The purpose of the study is to show a proposal of an extension of a one-dimensional speckle correlation method, which is primarily intended for determination of one-dimensional object's translation, for detection of general in-plane object's translation. In that view, a numerical simulation of a displacement of the speckle field as a consequence of general in-plane object's translation is presented. The translation components ax and ay representing the projections of a vector a of the object's displacement onto both x- and y-axes in the object plane (x, y) are evaluated separately by means of the extended one-dimensional speckle correlation method. Moreover, one can perform a distinct optimization of the method by reduction of intensity values representing detected speckle patterns. The theoretical relations between the translation components ax and ay of the object and the displacement of the speckle pattern for selected geometrical arrangement are mentioned and used for the testifying of the proposed method's rightness. PMID:24592180
Hamarová, Ivana; Smíd, Petr; Horváth, Pavel; Hrabovský, Miroslav
2014-01-01
The purpose of the study is to show a proposal of an extension of a one-dimensional speckle correlation method, which is primarily intended for determination of one-dimensional object's translation, for detection of general in-plane object's translation. In that view, a numerical simulation of a displacement of the speckle field as a consequence of general in-plane object's translation is presented. The translation components a x and a y representing the projections of a vector a of the object's displacement onto both x- and y-axes in the object plane (x, y) are evaluated separately by means of the extended one-dimensional speckle correlation method. Moreover, one can perform a distinct optimization of the method by reduction of intensity values representing detected speckle patterns. The theoretical relations between the translation components a x and a y of the object and the displacement of the speckle pattern for selected geometrical arrangement are mentioned and used for the testifying of the proposed method's rightness.
Zhang, Feng; Ikeda, Masao; Zhang, Shu-Ming; Liu, Jian-Ping; Tian, Ai-Qin; Wen, Peng-Yan; Cheng, Yang; Yang, Hui
2016-12-01
The polarization fields in c-plane InGaN/(In)GaN multiple quantum well (MQW) structures grown on sapphire substrate by metal-organic chemical vapor deposition are investigated in this paper. The indium composition in the quantum wells varies from 14.8 to 26.5% for different samples. The photoluminescence wavelengths are calculated theoretically by fully considering the related effects and compared with the measured wavelengths. It is found that when the indium content is lower than 17.3%, the measured wavelengths agree well with the theoretical values. However, when the indium content is higher than 17.3%, the measured ones are much shorter than the calculation results. This discrepancy is attributed to the reduced polarization field in the MQWs. For the MQWs with lower indium content, 100% theoretical polarization can be maintained, while, when the indium content is higher, the polarization field decreases significantly. The polarization field can be weakened down to 23% of the theoretical value when the indium content is 26.5%. Strain relaxation is excluded as the origin of the polarization reduction because there is no sign of lattice relaxation in the structures, judging by the X-ray diffraction reciprocal space mapping. The possible causes of the polarization reduction are discussed.
NASA Astrophysics Data System (ADS)
Zhang, Feng; Ikeda, Masao; Zhang, Shu-Ming; Liu, Jian-Ping; Tian, Ai-Qin; Wen, Peng-Yan; Cheng, Yang; Yang, Hui
2016-11-01
The polarization fields in c-plane InGaN/(In)GaN multiple quantum well (MQW) structures grown on sapphire substrate by metal-organic chemical vapor deposition are investigated in this paper. The indium composition in the quantum wells varies from 14.8 to 26.5% for different samples. The photoluminescence wavelengths are calculated theoretically by fully considering the related effects and compared with the measured wavelengths. It is found that when the indium content is lower than 17.3%, the measured wavelengths agree well with the theoretical values. However, when the indium content is higher than 17.3%, the measured ones are much shorter than the calculation results. This discrepancy is attributed to the reduced polarization field in the MQWs. For the MQWs with lower indium content, 100% theoretical polarization can be maintained, while, when the indium content is higher, the polarization field decreases significantly. The polarization field can be weakened down to 23% of the theoretical value when the indium content is 26.5%. Strain relaxation is excluded as the origin of the polarization reduction because there is no sign of lattice relaxation in the structures, judging by the X-ray diffraction reciprocal space mapping. The possible causes of the polarization reduction are discussed.
NASA Technical Reports Server (NTRS)
Zamula, G. N.; Ierusalimsky, K. M.; Kalmykova, G. S.; Fomin, V. P.
1998-01-01
The present paper is a final technical report within the NCCW-1-233 research program (dated June 1, 1997) accomplished as a part of co-operation between United States' NASA and Russia's Goskomoboronprom in aeronautics, and continues similar NCCW-73 and NCC-1-233 programs accomplished in 1996 and 1997, respectively. The report concludes studies in two domains, "Analyzing the effect of skin postbuckling on general stresses and strains in a composite structure" and "Evaluating the effect of skin postbuckling behavior on general stability of a composite structure"; the work was fulfilled in compliance with NCC-1-233 requirements (as of June 1, 1997). Also, the present studies may be regarded as a partial generalization of efforts in [1, 2] conducted within the above programs in what concerns postbuckling behavior of composite structures.
Zapolski, Tamika C B; Banks, Devin E; Lau, Katherine S L; Aalsma, Matthew C
2017-08-08
Although many juvenile offenders report experiencing police injustice, few studies have examined how this source of strain may impact youths' behavioral outcomes, including risk for future recidivism. This study begins to address that gap in the literature. We applied the general strain theory as our theoretical framework to examine the interactive effect of perceived police injustice and moral disengagement on juvenile aggressive behavior. Our sample included 95 juvenile offenders who completed questionnaires on measures of perceived police injustice and moral disengagement. Results supported our hypothesis, such that moral disengagement predicted past month aggression among juvenile offenders, but only by youth who reported mean and high levels of perceived police injustice. While more research is needed in this area, this study's findings underscore the need to address both perceived police engagement and moral disengagement among youth at-risk of engaging in delinquent behaviors. Implications for intervention programs are also presented.
General Strain Theory and Delinquency: Extending a Popular Explanation to American Indian Youth*
Eitle, David; Eitle, Tamela McNulty
2014-01-01
Despite evidence that American Indian adolescents are disproportionately involved in crime and delinquent behavior, there exists scant research exploring the correlates of crime among this group. We posit that Agnew’s (1992) General Strain Theory (GST) is well suited to explain American Indian delinquent activity. Using the National Longitudinal Study of Adolescent Health, we examined a subsample of American Indian students—a study that represents, to the best of our knowledge, the initial published test of GST principles used to explain AI delinquent behavior. Overall, we find mixed support for the core principles of GST applying to AI delinquent behavior. We also found evidence that some of the personal and social resources identified by Agnew condition the strain-delinquent behavior relationship, albeit, sometimes in ways that are not entirely consistent with GST. PMID:27217594
[Juvenile criminality: general strain theory and the reactive-proactive aggression trait].
Greco, Romy; Curci, Antonietta; Grattagliano, Ignazio
2009-01-01
The aims of the present study are to test General Strain Theory's (GST) assumptions, and to integrate the model including the proactive-reactive aggression trait. GST hypothesizes crime to be enacted in response to extra-personal stimuli (strain) and their subsequent negative emotions, especially anger. However, there exist also internally-driven manifestations of crime (instrumental or proactive), motivated by stimuli that are of an intrapersonal origin. Further, individuals differ to each other in the tendency to commit reactive or proactive or both manifestations of crime. With the goal to gain a more comprehensive model, GST variables and the reactive-proactive aggression trait are together tested as to their ability to predict criminal behaviour. Participants in the present research are 68 adolescent males with age ranging from 14 to 19 (M = 16.94, SD = 0.95). Half of the participants were jailed adolescents at the Fornelli Juvenile Detention Centre in Bari, while the remaining were adolescents with no criminal record, matched for age and level of education with the former group. An interview was administered to assess the experienced strain events, anger, and crime committed by the participants in the three months preceding the interview and also before. The reactive-proactive aggression trait was additionally measured. Results of the present study supported GST's assumptions, and confirmed the utility of integrating the model to include the proactive-reactive aggression trait. Strain events experienced in three-month time were found to influence property and violent offences committed by participants in the same time-interval as well as over this time. Furthermore,jailed participants were more likely to react with anger, and violence to strain events than non-jailed individuals, although the number of events experienced by both groups in the preceding months is similar. Finally, the results of the present study showed that proactive aggression is a strong
Lin, Wen-Hsu; Cochran, John K; Mieczkowski, Thomas
2011-01-01
Using a national probability sample of adolescents (12–17), this study applies general strain theory to how violent victimization, vicarious violent victimization, and dual violent victimization affect juvenile violent/property crime and drug use. In addition, the mediating effect and moderating effect of depression, low social control, and delinquent peer association on the victimization–delinquency relationship is also examined. Based on SEM analyses and contingency tables, the results indicate that all three types of violent victimization have significant and positive direct effects on violent/property crime and drug use. In addition, the expected mediating effects and moderating effects are also found. Limitations and future directions are discussed.
Bertacca, Daniele; Maartens, Roy; Raccanelli, Alvise; Clarkson, Chris E-mail: Roy.Maartens@port.ac.uk E-mail: Clarkson@maths.uct.ac.za
2012-10-01
We extend previous analyses of wide-angle correlations in the galaxy power spectrum in redshift space to include all general relativistic effects. These general relativistic corrections to the standard approach become important on large scales and at high redshifts, and they lead to new terms in the wide-angle correlations. We show that in principle the new terms can produce corrections of nearly 10% on Gpc scales over the usual Newtonian approximation. General relativistic corrections will be important for future large-volume surveys such as SKA and Euclid, although the problem of cosmic variance will present a challenge in observing this.
NASA Astrophysics Data System (ADS)
Bakhshi Khaniki, H.; Hosseini-Hashemi, Sh
2017-06-01
This paper presents the buckling behavior of tapered small-scale beams in the framework of nonlocal strain gradient theory. Three different types of cross-sectional variation are proposed—width variation, thickness variation and a combination of both. The Euler-Bernoulli beam model, nonlocal strain gradient theory and Hamilton’s principle are employed to achieve the governing equations of small-scale beams. A generalized differential quadrature method is used to solve the governing equations for all three nonuniformity models. In order to comprehend the influence of a nonuniform cross section, a parametric study is presented and the effects of strain gradient, nonlocal elasticity and all three types of nonuniformity on the critical buckling load are presented. It is shown that such nonuniformities have a significant effect on the buckling behavior of small-scale beams. Accordingly, with the wide application of tapered small-scale beams in many devices, this study could be a step forward in understanding, predicting and controlling such behaviors.
Dunnington, Benjamin D; Schmidt, J R
2012-06-12
Natural bond orbital (NBO) analysis is a powerful analysis technique capable of generating intuitive chemical representations of otherwise complex quantum mechanical electronic structure results, yielding a localized "Lewis-like" description of bonding and reactivity. We generalize this algorithm to periodic systems, thus expanding the scope of NBO analysis to bulk materials and/or periodic surface models. We employ a projection scheme to further expand the algorithm's applicability to ubiquitous plane-wave density functional theory (PW DFT) calculations. We also present a variety of example applications: examining bulk bonding and surface reconstruction and elucidating fundamental aspects of heterogeneous catalysis-all derived from rigorous underlying PW DFT calculations.
Chen, X Y; Pan, X H; Chen, W; Chen, S S; Huang, J Y; Ye, Z Z
2016-10-15
A large degree of polarization (ρ) of photoluminescence (PL) approximate to 1 is obtained in each nonpolar a-plane Mg_{x}Zn_{1-x}O layer grown by plasma-assisted molecular beam epitaxy (MBE) with x=0.01, 0.03, and 0.10, respectively. Anisotropic in-plane strains are selectively introduced by using foreign substrates and doping with different Mg contents, which strongly modify the valence band structures, leading to anisotropic optical properties. A polarized Raman measurement shows that anisotropic in-plane strains along the y and z axes increase with the increasing Mg contents. Polarized PL spectra show that ρ gradually increases to 0.97 with decreasing in-plane strains, resulting from an increasing difference in transition energy (ΔE) between E⊥c and E‖c caused by a lift of the degeneracy of valence band structures. The obtained highly polarized emission is close to linear polarized light, which is desirable in the backlighting of liquid crystal displays.
Doostparast Torshizi, Abolfazl; Fazel Zarandi, Mohammad Hossein
2015-09-01
This paper considers microarray gene expression data clustering using a novel two stage meta-heuristic algorithm based on the concept of α-planes in general type-2 fuzzy sets. The main aim of this research is to present a powerful data clustering approach capable of dealing with highly uncertain environments. In this regard, first, a new objective function using α-planes for general type-2 fuzzy c-means clustering algorithm is represented. Then, based on the philosophy of the meta-heuristic optimization framework 'Simulated Annealing', a two stage optimization algorithm is proposed. The first stage of the proposed approach is devoted to the annealing process accompanied by its proposed perturbation mechanisms. After termination of the first stage, its output is inserted to the second stage where it is checked with other possible local optima through a heuristic algorithm. The output of this stage is then re-entered to the first stage until no better solution is obtained. The proposed approach has been evaluated using several synthesized datasets and three microarray gene expression datasets. Extensive experiments demonstrate the capabilities of the proposed approach compared with some of the state-of-the-art techniques in the literature. Copyright © 2014 Elsevier Ltd. All rights reserved.
1988-09-01
properties.> Moreover, it is found that whether or not a failure zone is incorporated into the model si nif icantly influences both quantitatively and...Moreover, it is found that whether or not a failure zone is incorporated into the model significantly influences both quantitatively and...Hopf technique, Willis constructed the dynamic stress intensity factor (SIP) for a standard linear solid material model and general crack face
de Lacerda, Jackeline Rossetti Mateus; da Silva, Thais Freitas; Vollú, Renata Estebanez; Marques, Joana Montezano; Seldin, Lucy
2016-01-01
Eight strains isolated from the stems of Lippia sidoides were identified as belonging to Lactococcus lactis, a bacterial species considered as "generally recognized as safe". Their capacity to solubilize/mineralize phosphate was tested in vitro with different inorganic and organic phosphorus (P) sources. All strains were able to solubilize calcium phosphate as an inorganic P source, and the best result was observed with strain 003.41 which solubilized 31 % of this P source. Rock phosphate, a mined rock containing high amounts of phosphate bearing minerals, was solubilized by five strains. When calcium phytate was the organic P source used, the majority of the strains tested showed phosphate mineralization activity. Moreover, all strains were able to solubilize/mineralize phosphate from poultry litter, a complex P source containing inorganic and predominantly organic P. The presence of genes coding for phytase and alkaline phosphatase was searched within the strains studied. However, only gene sequences related to alkaline phosphatase (phoA and phoD) could be detected in the majority of the strains (excepting strain 006.29) with identities varying from 67 to 88 %. These results demonstrate for the first time the potential of L. lactis strains for phosphate solubilization/mineralization activity using a broad spectrum of P sources; therefore, they are of great importance for the future development of more safe bioinoculants with possible beneficial effects for agriculture.
Jana, Biman; Onuchic, José N
2016-08-01
A structure-based model of myosin motor is built in the same spirit of our early work for kinesin-1 and Ncd towards physical understanding of its mechanochemical cycle. We find a structural adaptation of the motor head domain in post-powerstroke state that signals faster ADP release from it compared to the same from the motor head in the pre-powerstroke state. For dimeric myosin, an additional forward strain on the trailing head, originating from the postponed powerstroke state of the leading head in the waiting state of myosin, further increases the rate of ADP release. This coordination between the two heads is the essence of the processivity of the cycle. Our model provides a structural description of the powerstroke step of the cycle as an allosteric transition of the converter domain in response to the Pi release. Additionally, the variation in structural elements peripheral to catalytic motor domain is the deciding factor behind diverse directionalities of myosin motors (myosin V & VI). Finally, we observe that there are general rules for functional molecular motors across the different families. Allosteric structural adaptation of the catalytic motor head in different nucleotide states is crucial for mechanochemistry. Strain-mediated coordination between motor heads is essential for processivity and the variation of peripheral structural elements is essential for their diverse functionalities.
A General Bayesian Approach to Analyzing Diallel Crosses of Inbred Strains
Lenarcic, Alan B.; Svenson, Karen L.; Churchill, Gary A.; Valdar, William
2012-01-01
The classic diallel takes a set of parents and produces offspring from all possible mating pairs. Phenotype values among the offspring can then be related back to their respective parentage. When the parents are diploid, sexed, and inbred, the diallel can characterize aggregate effects of genetic background on a phenotype, revealing effects of strain dosage, heterosis, parent of origin, epistasis, and sex-specific versions thereof. However, its analysis is traditionally intricate, unforgiving of unplanned missing information, and highly sensitive to imbalance, making the diallel unapproachable to many geneticists. Nonetheless, imbalanced and incomplete diallels arise frequently, albeit unintentionally, as by-products of larger-scale experiments that collect F1 data, for example, pilot studies or multiparent breeding efforts such as the Collaborative Cross or the Arabidopsis MAGIC lines. We present a general Bayesian model for analyzing diallel data on dioecious diploid inbred strains that cleanly decomposes the observed patterns of variation into biologically intuitive components, simultaneously models and accommodates outliers, and provides shrinkage estimates of effects that automatically incorporate uncertainty due to imbalance, missing data, and small sample size. We further present a model selection procedure for weighing evidence for or against the inclusion of those components in a predictive model. We evaluate our method through simulation and apply it to incomplete diallel data on the founders and F1's of the Collaborative Cross, robustly characterizing the genetic architecture of 48 phenotypes. PMID:22345610
Jana, Biman; Onuchic, José N.
2016-01-01
A structure-based model of myosin motor is built in the same spirit of our early work for kinesin-1 and Ncd towards physical understanding of its mechanochemical cycle. We find a structural adaptation of the motor head domain in post-powerstroke state that signals faster ADP release from it compared to the same from the motor head in the pre-powerstroke state. For dimeric myosin, an additional forward strain on the trailing head, originating from the postponed powerstroke state of the leading head in the waiting state of myosin, further increases the rate of ADP release. This coordination between the two heads is the essence of the processivity of the cycle. Our model provides a structural description of the powerstroke step of the cycle as an allosteric transition of the converter domain in response to the Pi release. Additionally, the variation in structural elements peripheral to catalytic motor domain is the deciding factor behind diverse directionalities of myosin motors (myosin V & VI). Finally, we observe that there are general rules for functional molecular motors across the different families. Allosteric structural adaptation of the catalytic motor head in different nucleotide states is crucial for mechanochemistry. Strain-mediated coordination between motor heads is essential for processivity and the variation of peripheral structural elements is essential for their diverse functionalities. PMID:27494025
Optimality of general lattice transformations with applications to the Bain strain in steel
Koumatos, K.
2016-01-01
This article provides a rigorous proof of a conjecture by E. C. Bain in 1924 on the optimality of the so-called Bain strain based on a criterion of least atomic movement. A general framework that explores several such optimality criteria is introduced and employed to show the existence of optimal transformations between any two Bravais lattices. A precise algorithm and a graphical user interface to determine this optimal transformation is provided. Apart from the Bain conjecture concerning the transformation from face-centred cubic to body-centred cubic, applications include the face-centred cubic to body-centred tetragonal transition as well as the transformation between two triclinic phases of terephthalic acid. PMID:27274692
Childhood abuse and criminal behavior: testing a general strain theory model.
Watts, Stephen J; McNulty, Thomas L
2013-10-01
This article draws on general strain theory (GST) to develop and test a model of the childhood abuse-crime relationship. Using data from the National Longitudinal Study of Adolescent Health (Add Health),(1) we find that early childhood physical and sexual abuse are robust predictors of offending in adolescence, for the full sample and in equations disaggregated by gender. GST is partially supported in that the effects of childhood physical abuse on offending for both females and males are mediated by an index of depression symptoms, whereas the effect of sexual abuse among females appears to be mediated largely by closeness to mother. The effect of childhood sexual abuse among males, however, is more robust than among females and it persists despite controls for low self-control, ties to delinquent peers, school attachment, and closeness to mother. Theoretical implications of the findings are discussed.
In-plane magnetization-induced quantum anomalous Hall effect.
Liu, Xin; Hsu, Hsiu-Chuan; Liu, Chao-Xing
2013-08-23
The quantum Hall effect can only be induced by an out-of-plane magnetic field for two-dimensional electron gases, and similarly, the quantum anomalous Hall effect has also usually been considered for systems with only out-of-plane magnetization. In the present work, we predict that the quantum anomalous Hall effect can be induced by in-plane magnetization that is not accompanied by any out-of-plane magnetic field. Two realistic two-dimensional systems, Bi2Te3 thin film with magnetic doping and HgMnTe quantum wells with shear strains, are presented and the general condition for the in-plane magnetization-induced quantum anomalous Hall effect is discussed based on the symmetry analysis. Nonetheless, an experimental setup is proposed to confirm this effect, the observation of which will pave the way to search for the quantum anomalous Hall effect in a wider range of materials.
Prospective effect of job strain on general and central obesity in the Whitehall II Study.
Brunner, Eric J; Chandola, Tarani; Marmot, Michael G
2007-04-01
Positive energy balance is the major cause of obesity, and chronic stress may be a contributory factor. The authors examined cumulative work stress, using the Job Strain Questionnaire on four occasions, as a predictor of obesity in a prospective 19-year study of 6,895 men and 3,413 women (aged 35-55 years) in the Whitehall II cohort in London, United Kingdom (baseline: 1985-1988). A dose-response relation was found between work stress and risk of general obesity (body mass index > or =30 kg/m(2)) and central obesity (waist circumference >102 cm in men, >88 cm in women) that was largely independent of covariates. The imputed odds ratios of body mass index obesity for one, two, and three or more reports of work stress adjusted for age, sex, and social position were 1.17, 1.24, and 1.73 (trend p < 0.01), respectively. For waist obesity, the corresponding findings were 1.17, 1.41, and 1.61 (trend p < 0.01). Work stress effect was modestly attenuated after exclusion of obese individuals at baseline and further adjustments for smoking; intakes of dietary fiber, fruits and vegetables, and alcohol; and levels of physical activity during follow-up. This study provides prospective, population-based evidence that chronic work stress predicts general and central obesity.
Steele, Jennifer L
2016-10-14
To extend our knowledge of general strain theory by exploring how under-researched strains such as racial discrimination, witnessing violence, physical victimization and verbal bullying affect adolescent substance use while considering differences according to racial identification. This research utilized data from wave three of the Project on Human Development in Chicago Neighborhoods. Statistical analysis was primarily composed of path analysis using full information maximum likelihood parameter estimates. The findings reveal that reporting fear decreased alcohol and marijuana use among adolescents and that racial discrimination, witnessing violence, and being the victim of verbal bullying indirectly affected marijuana and alcohol use through fear. No support was found for depression as a mediating variable. Physical victimization was the only social strain that had a direct positive effect on marijuana and alcohol use but only for Hispanics and African Americans. The results suggest that strains may be operating differently and there may be differential levels of exposure to certain strains according to one's race.
Howard-Quijano, Kimberly; Anderson-Dam, John; McCabe, Melissa; Hall, Michael; Mazor, Einat; Mahajan, Aman
2015-08-01
The primary aim of this study was to use speckle-tracking strain imaging to evaluate the effect of general anesthesia (GA) and positive-pressure ventilation (PPV) on left atrial (LA) mechanics. The authors hypothesized that GA and PPV would be associated with a decrease in LA strain. The secondary aims were to investigate the effects of GA and PPV on traditional Doppler-derived measures of LA function and Doppler echocardiographic grade of diastolic function. A prospective observational study. A university hospital. Adult patients undergoing cardiac surgery. Transthoracic echocardiography was performed at baseline and under GA with PPV. Changes in LA function associated with GA and PPV were assessed using LA speckle-tracking strain imaging. A reduction was observed in LA peak longitudinal strain (24% v 18%, p<0.001) and preatrial contraction strain (13% v 8%, p<0.001). No difference was seen in LA contraction strain or atrial ejection fraction. Indexed LA volume and Doppler diastolic indices also were reduced significantly, and 39% of patients had a change in measured diastolic grade under GA with PPV. Speckle-tracking strain imaging of the left atrium demonstrated that GA and PPV had a significant impact on LA mechanics by decreasing strain measures of LA preload, with a lesser effect on LA contractility. Copyright © 2015 Elsevier Inc. All rights reserved.
NASA Technical Reports Server (NTRS)
Krempl, Erhard; Hong, Bor Zen
1989-01-01
A macromechanics analysis is presented for the in-plane, anisotropic time-dependent behavior of metal matrix laminates. The small deformation, orthotropic viscoplasticity theory based on overstress represents lamina behavior in a modified simple laminate theory. Material functions and constants can be identified in principle from experiments with laminae. Orthotropic invariants can be repositories for tension-compression asymmetry and for linear elasticity in one direction while the other directions behave in a viscoplastic manner. Computer programs are generated and tested for either unidirectional or symmetric laminates under in-plane loading. Correlations with the experimental results on metal matrix composites are presented.
NASA Technical Reports Server (NTRS)
Krempl, Erhard; Hong, Bor Zen
1989-01-01
A macromechanics analysis is presented for the in-plane, anisotropic time-dependent behavior of metal matrix laminates. The small deformation, orthotropic viscoplasticity theory based on overstress represents lamina behavior in a modified simple laminate theory. Material functions and constants can be identified in principle from experiments with laminae. Orthotropic invariants can be repositories for tension-compression asymmetry and for linear elasticity in one direction while the other directions behave in a viscoplastic manner. Computer programs are generated and tested for either unidirectional or symmetric laminates under in-plane loading. Correlations with the experimental results on metal matrix composites are presented.
NASA Astrophysics Data System (ADS)
Betka, P. M.; Seeber, L.; Steckler, M. S.
2015-12-01
The Indo-Burma fold-thrust belt (FTB) in northeast India and Myanmar records shortening of a forearc prism resulting from ongoing collision of the Burma microplate and the Ganges-Brahmaputra Delta. A >5 km thick succession of deep water, deltaic and tidal as well as fluvial deposits that span the Oligocene to present were deformed to form a ~400 km wide FTB between 91.5-96°E longitude. India-Eurasia convergence across the Indo-Burma region trends northeast and is highly oblique to the northerly structural trend of the FTB. According to geodetic data, 21 mm/yr of dextral shear and 18 mm/yr of approximately east-west shortening must be accommodated within the FTB between the active thrust front in Bangladesh (90.5°E) and the Sagaing Fault in Myanmar (96°E). This paper presents new surface geologic data collected along a ~250 km transect that crosses 15 anticline-syncline pairs between the cities of Argatala (~91.2°E) and Champhai (93.3°E), the part of FTB exposing syn-Himalayan sediment, to determine the degree of noncoaxial shear that is accommodated internally within the belt. Results indicate that the majority of the folds are upright or asymmetric horizontal folds that are either concentric or have a narrow hinge (chevron folds) and form open—closed interlimb angles which generally tighten from the foreland toward the hinterland. A cylindrical best fit describes the data well and shows dominantly east-west shortening with a horizontal north-trending regional fold axis (005/01 ± 2°). Shortening was partly accommodated by flexural slip. Flexural slip-lineations (n=32) are subperpendicular to the regional fold axis. In some locations the limbs of folds are breached by thrust faults that dip either east or west and strike north. Incremental strain axes calculated from the flexural-slip surfaces and thrust faults (n=61) indicate horizontal west-trending shortening (279/03 ± 8°) and vertical extension that is kinematically compatible with folding. Altogether
Gao, Yunjiao; Wong, Dennis S W; Yu, Yanping
2016-01-01
Using a sample of 1,163 adolescents from four middle schools in China, this study explores the intervening process of how adolescent maltreatment is related to delinquency within the framework of general strain theory (GST) by comparing two models. The first model is Agnew's integrated model of GST, which examines the mediating effects of social control, delinquent peer affiliation, state anger, and depression on the relationship between maltreatment and delinquency. Based on this model, with the intent to further explore the mediating effects of state anger and depression and to investigate whether their effects on delinquency can be demonstrated more through delinquent peer affiliation and social control, an extended model (Model 2) is proposed by the authors. The second model relates state anger to delinquent peer affiliation and state depression to social control. By comparing the fit indices and the significance of the hypothesized paths of the two models, the study found that the extended model can better reflect the mechanism of how maltreatment contributes to delinquency, whereas the original integrated GST model only receives partial support because of its failure to find the mediating effects of state negative emotions.
NASA Astrophysics Data System (ADS)
Matzen, Sylvia; Nesterov, Oleksiy; Rispens, Gijsbert; Heuver, Jeroen; Noheda, Beatriz; Biegalski, Michael; Christen, Hans
2014-03-01
Understanding and controlling domain formation in nanoscale ferroelectrics is interesting from a fundamental point of view and of great technological importance. Increasing miniaturization allows creating complex domain structures, offering novel functionalities that could be particularly useful for the development of nanoelectronic devices. While most studies in thin films focus on domain patterns with up/down polarization for ferroelectric memories, domain structures with purely in-plane polarization have not been much investigated. However, such structures are potentially useful in optical devices or to avoid depolarization fields in ultra-thin films, as long as the domains can be addressed and switched. We use a combination of compositional substitutions and epitaxial growth on a substrate in order to tune the domain configuration. The substitution of Pb by Sr in PbxSr1-xTiO3 thin films grown epitaxially on (110)-DyScO3, stabilizes a domain structure with purely in-plane polarization. In this work, we show that it is possible to stabilize and control a complex domain architecture at two different length scales, yielding periodic ferroelectric nano-domains with purely in-plane polarization. Most importantly, these in-plane domains can be switched by a scanning probe.
NASA Astrophysics Data System (ADS)
Kamas, Tuncay; Lin, Bin; Giurgiutiu, Victor
2013-04-01
This paper discusses theoretical analysis of electro-mechanical impedance spectroscopy (EMIS) of piezoelectric wafer active sensor (PWAS). Both free and constrained PWAS EMIS models are developed for in-plane (lengthwise) and outof plane (thickness wise) mode. The paper starts with the general piezoelectric constitutive equations that express the linear relation between stress, strain, electric field and electric displacement. This is followed by the PWAS EMIS models with two assumptions: 1) constant electric displacement in thickness direction (D3) for out-of-plane mode; 2) constant electric field in thickness direction (E3) for in-plane mode. The effects of these assumptions on the free PWAS in-plane and out-of-plane EMIS models are studied and compared. The effects of internal damping of PWAS are considered in the analytical EMIS models. The analytical EMIS models are verified by Coupled Field Finite Element Method (CF-FEM) simulations and by experimental measurements. The extent of the agreement between the analytical and experimental EMIS results is discussed. The paper ends with summary, conclusions, and suggestions for future work.
Borcherdt, R.D.
1988-01-01
Dilatational earth strain, associated with the radiation fields for several hundred local, regional, and teleseismic earthquakes, has been recorded over an extended bandwidth and dynamic range at four borehole sites near the San Andreas fault, CA. The general theory of linear viscoelasticity is applied to account for anelasticity of the near-surface materials and to provide a mathematical basis for interpretation of seismic radiation fields as detected simultaneously by co-located volumetric strain meters and seismometers. The general theory is applied to describe volumetric strain and displacement for general (homogeneous or inhomogeneous) P and S waves in an anelastic whole space. Solutions to the free-surface reflection problems for incident general P and S-I waves are used to evaluate the effect of the free surface on observations from co-located sensors. Corresponding expressions are derived for a Rayleigh-type surface wave on a linear viscoelastic half-space. The theory predicts a number of anelastic wave field characteristics that can be inferred from observation of volumetric strains and displacement fields as detected by co-located sensors that cannot be inferred from either sensor alone. -from Author
Suzuki, N; Mita, K; Watakabe, M; Akataki, K; Okagawa, T; Kimizuka, M
1998-01-01
The purpose of this study was to use an non-invasive method to determine whether strain on the gastrocnemii and hamstrings influences postural balance in spastic cerebral palsy (CP). Changes in alignment during standing posture with subjects positioned on a platform that was gradually inclined were measured in 10 normal children and 11 children with CP. The changes in postural alignment were plotted and geometric models used to determine the lines where the gastrocnemii and hamstrings were maximally stretched. In this way the relationship between postural alignment and the amount of strain on the gastrocnemii and hamstrings was investigated. On the inclined platform, which caused ankle joints to become dorsiflexed as the inclination angle increased, the gastrocnemii began to be strained and the hip joints began to be flexed (trunk bent forward) at the same time. In the children with CP, the gastrocnemii were more strained by smaller degrees of inclination. Furthermore, there was one child with CP whose hamstrings were also strained on the inclined platform. We confirmed that postural balance was affected by strain on the gastrocnemii and hamstrings.
NASA Technical Reports Server (NTRS)
Jones, M. H.; Bubsey, R. T.; Brown, W. F., Jr.; Bucci, R. J.; Collis, S. F.; Kohm, R. F.; Kaufman, J. G.
1977-01-01
A description is presented of studies which have been conducted to establish an improved technology base for a use of the sharply notched cylindrical specimen in quality assurance tests of aluminum alloy products. The results are presented of an investigation of fundamental variables associated with specimen preparation and testing, taking into account the influence of the notch root radius, the eccentricity of loading, the specimen diameter, and the notch depth on the sharp notch strength. Attention is given to the statistical procedures which are necessary to establish correlations between the sharp notch strength and the plane-strain fracture toughness for high-strength aluminum alloys.
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.
NASA Astrophysics Data System (ADS)
Le Page, Yvon; Saxe, Paul
2002-03-01
A symmetry-general approach for the least-squares, therefore precise, extraction of elastic coefficients for strained materials is reported. It analyzes stresses calculated ab initio for properly selected strains. The problem, its implementation, and its solution strategy all differ radically from a previous energy-strain approach that we published last year, but the normal equations turn out to be amenable to the same constrainment scheme that makes both approaches symmetry general. The symmetry considerations governing the automated selection of appropriately strained models and their Cartesian systems are detailed. The extension to materials under general stress is discussed and implemented. VASP was used for ab initio calculation of stresses. A comprehensive range of examples includes a triclinic material (kyanite) and simple materials with a range of symmetries at zero pressure, MgO under hydrostatic pressure, Ti4As3 under [001] uniaxial strain, and Si under [001] uniaxial stress. The MgO case agrees with recent experimental work including elastic coefficients as well as their first and second derivatives. The curves of elastic coefficients for Si show a gradual increase in the 33 compliance coefficient, leading to a collapse of the material at -11.7 GPa, compared with -12.0 GPa experimentally. Interpretation of results for Be using two approximations [local density (LDA), generalized gradient (GGA)], two approaches (stress strain and energy strain), two potential types (projector augmented wave and ultrasoft), and two quantum engines (VASP and ORESTES) expose the utmost importance of the cell data used for the elastic calculations and the lesser importance of the other factors. For stiffness at relaxed cell data, differences are shown to originate mostly in the considerable overestimation of the residual compressive stresses at x-ray cell data by LDA, resulting in a smaller relaxed cell, thus larger values for diagonal stiffness coefficients. The symmetry
Robertson, Angela R.; Stein, Judith A.; Schaefer-Rohleder, Lacey
2011-01-01
This study tested Agnew’s General Strain Theory (GST) by examining the roles of anger, anxiety, and maladaptive coping in mediating the relationship between strain and three outcomes (serious delinquency, minor delinquency, and continued involvement in the juvenile justice system) among adolescent female offenders (N = 261). Strains consisted of adverse life events and exposure to Hurricane Katrina. Greater exposure to Hurricane Katrina was directly related to serious delinquency and maladaptive coping. Hurricane Katrina also had an indirect effect on minor delinquency and Post–Katrina juvenile justice involvement mediated through maladaptive coping. Adverse life events were associated with increased anger, anxiety, and maladaptive coping. Anger mediated the relationship between adverse life events and serious delinquency. Anxiety mediated the relationship between adverse life events and minor delinquency. Maladaptive coping strategies were associated with minor delinquency and juvenile justice involvement. Findings lend support to GST. PMID:21572904
Generalizing J 2 flow theory: Fundamental issues in strain gradient plasticity
NASA Astrophysics Data System (ADS)
Hutchinson, John W.
2012-08-01
It has not been a simple matter to obtain a sound extension of the classical J 2 flow theory of plasticity that incorporates a dependence on plastic strain gradients and that is capable of capturing size-dependent behaviour of metals at the micron scale. Two classes of basic extensions of classical J 2 theory have been proposed: one with increments in higher order stresses related to increments of strain gradients and the other characterized by the higher order stresses themselves expressed in terms of increments of strain gradients. The theories proposed by Muhlhaus and Aifantis in 1991 and Fleck and Hutchinson in 2001 are in the first class, and, as formulated, these do not always satisfy thermodynamic requirements on plastic dissipation. On the other hand, theories of the second class proposed by Gudmundson in 2004 and Gurtin and Anand in 2009 have the physical deficiency that the higher order stress quantities can change discontinuously for bodies subject to arbitrarily small load changes. The present paper lays out this background to the quest for a sound phenomenological extension of the rateindependent J 2 flow theory of plasticity to include a dependence on gradients of plastic strain. A modification of the Fleck-Hutchinson formulation that ensures its thermodynamic integrity is presented and contrasted with a comparable formulation of the second class where in the higher order stresses are expressed in terms of the plastic strain rate. Both versions are constructed to reduce to the classical J 2 flow theory of plasticity when the gradients can be neglected and to coincide with the simpler and more readily formulated J 2 deformation theory of gradient plasticity for deformation histories characterized by proportional straining.
Bullying Victimization and Adolescent Self-Harm: Testing Hypotheses from General Strain Theory
ERIC Educational Resources Information Center
Hay, Carter; Meldrum, Ryan
2010-01-01
Self-harm is widely recognized as a significant adolescent social problem, and recent research has begun to explore its etiology. Drawing from Agnew's (1992) social psychological strain theory of deviance, this study considers this issue by testing three hypotheses about the effects of traditional and cyber bullying victimization on deliberate…
Bullying Victimization and Adolescent Self-Harm: Testing Hypotheses from General Strain Theory
ERIC Educational Resources Information Center
Hay, Carter; Meldrum, Ryan
2010-01-01
Self-harm is widely recognized as a significant adolescent social problem, and recent research has begun to explore its etiology. Drawing from Agnew's (1992) social psychological strain theory of deviance, this study considers this issue by testing three hypotheses about the effects of traditional and cyber bullying victimization on deliberate…
A generalized speckle tracking algorithm for ultrasonic strain imaging using dynamic programming.
Jiang, Jingfeng; Hall, Timothy J
2009-11-01
This study developed an improved motion estimation algorithm for ultrasonic strain imaging that employs a dynamic programming technique. In this article, we model the motion estimation task as an optimization problem. Since tissue motion under external mechanical stimuli often should be reasonably continuous, a set of cost functions combining correlation and various levels of motion continuity constraint were used to regularize the motion estimation. To solve the optimization problem with a reasonable computational load, a dynamic programming technique that does not require iterations was used to obtain displacement vectors in integer precision. Then, a subsample estimation algorithm was used to calculate local displacements in fractional precision. Two implementation schemes were investigated with in vivo ultrasound echo data sets. We found that the proposed algorithm provides more accurate displacement estimates than our previous algorithm for in vivo clinical data. In particular, the new algorithm is capable of tracking motion in more complex anatomy and increases strain image consistency in a sequence of images. Preliminary results also suggest that a significantly longer sequence of high contrast strain images could be obtained with the new algorithm compared with the previous algorithm. The new algorithm can also tolerate larger motion discontinuities (e.g., cavity in an anthropomorphic uterine phantom).
A Generalized Speckle Tracking Algorithm for Ultrasonic Strain Imaging Using Dynamic Programming
Jiang, Jingfeng; Hall, Timothy J.
2009-01-01
This study developed an improved motion estimation algorithm for ultrasonic strain imaging that employs a dynamic programming technique. In this paper, we model the motion estimation task as an optimization problem. Since tissue motion under external mechanical stimuli often should be reasonably continuous, a set of cost functions combining correlation and various levels of motion continuity constraint were used to regularize the motion estimation. To solve the optimization problem with a reasonable computational load, a dynamic programming technique that does not require iterations was used to obtain displacement vectors in integer precision. Then, a sub-sample estimation algorithm was used to calculate local displacements in fractional precision. Two implementation schemes were investigated with in vivo ultrasound echo data sets. We found that the proposed algorithm provides more accurate displacement estimates than our previous algorithm for in vivo clinical data. In particular, the new algorithm is capable of tracking motion in more complex anatomy and increases strain image consistency in a sequence of images. Preliminary results also suggest that a significantly longer sequence of high contrast strain images could be obtained with the new algorithm compared to the previous algorithm. The new algorithm can also tolerate larger motion discontinuities (e.g. cavity in an anthropomorphic uterine phantom). PMID:19682789
NASA Astrophysics Data System (ADS)
Lomakin, E. V.; Fedulov, B. N.
2013-07-01
The limit properties of many heterogeneous materials such as grounds, concrete, ceramics, cast-iron alloys, and various heat-resistant and powder materials, as well as the properties of many composite materials, depend on the loading conditions. Neglecting the effects exhibited by such materials may result in nonconservative limit load analysis for some types of loading and possibly in an overly increased end product weight by failing to take into account stronger material properties for other types of loading. This paper presents a possible approach to modeling the behavior of such materials under plastic deformation, which is demonstrated for the sample problem on the extension of a strip weakened by cuts with circular base. An analytic solution on the basis of a rigid-plastic model of the material and a numerical solution by the finite elementmethod with elastic strains and small strengthening taken into account are presented.
NASA Astrophysics Data System (ADS)
Morovvati, M. R.; Lalehpour, A.; Esmaeilzare, A.
2016-12-01
Reinforcing aluminum with SiC and B4C nano/micro particles can lead to a more efficient material in terms of strength and light weight. The influence of adding these particles to an aluminum 7075 matrix is investigated using chevron-notch fracture toughness test method. The reinforcing factors are type, size (micro/nano), and weight percent of the particles. The fracture parameters are maximum load, notch opening displacement, the work up to fracture and chevron notch plane strain fracture toughness. The findings demonstrate that addition of micro and nano size particles improves the fracture properties; however, increasing the weight percent of the particles leads to increase of fracture properties up to a certain level and after that due to agglomeration of the particles, the improvement does not happen for both particle types and size categories. Agglomeration of particles at higher amounts of reinforcing particles results in improper distribution of particles and reduction in mechanical properties.
Boukadida, J; Ben Abdallah, H; Boukadida, N
2003-11-01
Staphylococci remain among the main responsible bacteria for septicemia. The resistance to antibiotics already makes a prognosis difficult. We carried out a study on Staphylococcus isolated from blood culture on 3 years in general hospital in Tunisia. We present the different species and their sensitivity to antibiotics. S. aureus is the predominant isolated species. S. epidermidis is essentially isolated in newborn intensive care unit. The meticillino-resistance concerns 14% of the whole strains and 5.2 of the S. aureus. No resistance is found as regard the vancomycin and the pristinamycin; ofloxacine is inactive on 14.8% of strains and the gentamicine on 11.3%. The resistance of staphylococci of our study is lower than the rates reported in southern Europe and in North America.
Grigis, A; Farina, C; Moioli, F; Parea, M; Cirillo, D M; Goglio, A; Marchiaro, G
1995-06-01
During the 1989 calendar year, P. aeruginosa caused clinical infections in 0.46% of patients admitted to Ospedali Riuniti (a general hospital), Bergamo, Italy. Strains (n = 267) of P. aeruginosa were collected during this period, and epidemiological characteristics were studied. The mean prevalence of P. aeruginosa infection in inpatients was 1.1% (range 0.06-7.3), whereas outpatients showed a significantly lower prevalence of infection (0.05%). Strains were recovered from inpatients of surgical wards (n = 126; 47.2%), and outpatients (n = 15; 5.6%). Males were more often affected than females (2.7:1). Infection of the urinary tract was the most common (34.1%). Pseudomonas aeruginosa was also involved in lower respiratory tract infections (18.7%) and septicaemia (17.6%). Four typing methods were performed, i.e. serotyping, antibiotyping, pyocin typing, and restriction endonuclease analysis (REA). Serotypes O:11 and O:6 were endemic in the hospital. Some serotypes correlated with specific clinical wards. Pyocin typing was an unreliable epidemiological tool. However, antibiotyping showed the presence of some epidemic clusters, probably related to the antibiotic consumption of the patients. REA suggested the circulation of edemic P. aeruginosa strains in both the obstetrics and neurosurgery wards.
Families at Work: Strengths and Strains. The General Mills American Family Report 1980-81.
ERIC Educational Resources Information Center
General Mills, Inc., Minneapolis, Minn.
Fourth in a series of studies on the American family conducted for General Mills Corporation, this publication provides findings from a survey exploring the relationship between work and the family in contemporary society. Specifically, the survey explores how changes in the work force, especially the increase in numbers of working wives and…
ERIC Educational Resources Information Center
Drapela, Laurie A.
2006-01-01
General Strain Theory (GST) argues that drug use is one way adolescents mitigate negative emotions brought on by aversive environmental stimuli. To date, many of the empirical tests of the strain-drug use relationship have neglected to include measures of negative emotion, despite its prominence in GST's etiology of deviant behavior. The following…
ERIC Educational Resources Information Center
Drapela, Laurie A.
2006-01-01
General Strain Theory (GST) argues that drug use is one way adolescents mitigate negative emotions brought on by aversive environmental stimuli. To date, many of the empirical tests of the strain-drug use relationship have neglected to include measures of negative emotion, despite its prominence in GST's etiology of deviant behavior. The following…
The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli
Abram, Florence; Brennan, Fiona
2016-01-01
ABSTRACT Although Escherichia coli is generally considered to be predominantly a commensal of the gastrointestinal tract, a number of recent studies suggest that it is also capable of long-term survival and growth in environments outside the host. As the extraintestinal physical and chemical conditions are often different from those within the host, it is possible that distinct genetic adaptations may be required to enable this transition. Several studies have shown a trade-off between growth and stress resistance in nutrient-poor environments, with lesions in the rpoS locus, which encodes the stress sigma factor RpoS (σS). In this study, we investigated a unique collection of long-term soil-persistent E. coli isolates to determine whether the RpoS-controlled general stress response is altered during adaptation to a nutrient-poor extraintestinal environment. The sequence of the rpoS locus was found to be highly conserved in these isolates, and no nonsense or frameshift mutations were detected. Known RpoS-dependent phenotypes, including glycogen synthesis and γ-aminobutyrate production, were found to be conserved in all strains. All strains expressed the full-length RpoS protein, which was fully functional using the RpoS-dependent promoter reporter fusion PgadX::gfp. RpoS was shown to be essential for long-term soil survival of E. coli, since mutants lacking rpoS lost viability rapidly in soil survival assays. Thus, despite some phenotypic heterogeneity, the soil-persistent strains all retained a fully functional RpoS-regulated general stress response, which we interpret to indicate that the stresses encountered in soil provide a strong selective pressure for maintaining stress resistance, despite limited nutrient availability. IMPORTANCE Escherichia coli has been, and continues to be, used as an important indicator species reflecting potential fecal contamination events in the environment. However, recent studies have questioned the validity of this, since E
NASA Technical Reports Server (NTRS)
Grosveld, F.; Lameris, J.; Dunn, D.
1979-01-01
Experiments and a theoretical analysis were conducted to predict the noise reduction of inclined and curved panels. These predictions are compared to the experimental results with reasonable agreement between theory and experiment for panels under an oblique angle of sound incidence. Theoretical as well as experimental results indicate a big increase in noise reduction when a flat test panel is curved. Further curving the panel slightly decreases the noise reduction. Riveted flat panels are shown to give a higher noise reduction in the stiffness-controlled frequency region, while bonded panels are superior in this region when the test panel is curved. Experimentally measured noise reduction characteristics of flat aluminum panels with uniaxial in-plane stresses are presented and discussed. These test results indicate an important improvement in the noise reduction of these panels in the frequency range below the fundamental panel/cavity frequency.
NASA Astrophysics Data System (ADS)
Kuwabara, Hiroki; Menou, Nicolas; Funakubo, Hiroshi
2007-05-01
The growth and characterization of epitaxial (111)-oriented Pb(Zr0.35Ti0.65)O3 films deposited by metal organic chemical vapor deposition on (100)-oriented silicon substrates [(111)SrRuO3‖(111)Pt ‖(100)yttria-stabilizedzirconia‖(100)Si] are reported. The orientation, microstructure, and electric properties of these films are compared to those of fiber-textured highly (111)-oriented lead zirconate titanate (PZT) films deposited on (111)SrRuO3/(111)Pt/TiOx/SiO2/(100)Si substrates and epitaxial (111)-oriented PZT films deposited on (111)SrRuO3‖(111)SrTiO3 substrates. The ferroelectric properties of these films are not drastically influenced by the in-plane orientation of the film and by the strain state imposed by the underlying substrate. These results support the use of fiber-textured highly (111)-oriented films in highly stable ferroelectric capacitors.
CUTTING PLANE METHODS WITHOUT NESTED CONSTRAINT SETS
General conditions are given for the convergence of a class of cutting -plane algorithms without requiring that the constraint sets for the... cutting -planes include that of Kelley and a generalization of that used by Zoutendisk and Veinott. For algorithms with nested constraint sets, these
NASA Technical Reports Server (NTRS)
Freed, Alan D.
1995-01-01
The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.
Broken chiral symmetry on a null plane
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.
Borcherdt, R.D.; Johnston, M.J.S.; Glassmoyer, G.; Dietel, C.
2006-01-01
The 2004 Parkfield earthquake generated a unique set of near-field, high-resolution colocated measurements of acceleration, volumetric strain, and velocity at 11 stations in the General Earthquake Observation System (GEOS) array. The recordings indicate no precursory strain or displacement was discernable at sensitivities of 10-11 strain and 5 ?? 10 -8 m 25 sec prior to the earthquake at distances of 0.5 to 12 km of fault rupture. Coherent fault-parallel and fault-normal displacement pulses, observed along the fault north of the epicenter, are consistent with model predictions for "fling," directivity, and displacement for right-lateral, strike-slip fault rupture. The fault-parallel and fault-normal pulses imply apparent rupture velocities of 2.86 ?? 0.15 and 3.03 ?? 0.24 km/sec, respectively. Unprecedented high-resolution volumetric-strain recordings on opposite sides of the fault show that dynamic strains radiated from ruptured segments of the fault are more than an order of magnitude larger than final coseismic strain offsets associated with fault slip, suggesting that dynamic radiated strain may have contributed to the triggering of failure on unruptured segments. High-resolution recordings show that coseismic strain offsets occur abruptly over time intervals of less than 10 sec near the time of arrival of the dominant radiated fault-parallel and fault-normal displacements. Subsequent measurements show that the strain offsets continue to increase by as much as 69% in 5 min and 300% in 24 hr over that measured during initial fault slip at depth. Estimates of local material parameters from simultaneous measurements of volumetric strain and acceleration confirm seismic calibration factors previously measurable in situ only at tidal periods.
Baker, Thomas; Pelfrey, William V
2016-12-01
Guided by the propositions of general strain theory, this study examines the impact of experienced and anticipated strains on the delinquent coping of adolescents while accounting for the usage of social networking sites. Specifically, this study uses self-report survey data collected from 3,195 middle and high school students in a single Midwest city in the United States to explore the effect of experiencing the strains of traditional bullying victimization and cyberbullying victimization on adolescents self-reported soft drug use, hard drug use, and weapon carrying behavior. These relationships are explored among both frequent and infrequent users of social networking sites. Results indicate that cyberbullying victimization and the anticipated strain of feeling unsafe at or on the way to or from school are significantly and positively associated with all three mechanisms of delinquent coping among both frequent and infrequent social network users.
Petty, Nicola K; Foulds, Ian J; Pradel, Elizabeth; Ewbank, Jonathan J; Salmond, George P C
2006-06-01
A bacteriophage (phiIF3) capable of mediating generalized transduction in Serratia marcescens strain Db11 has been isolated and characterized. The genome of this Serratia strain has recently been sequenced and is likely to become the reference strain for S. marcescens researchers. phiIF3 is most likely a virulent phage, which can transduce markers at frequencies of 10(-6) transductants per p.f.u. It has a lipopolysaccharide receptor and was determined to have a latent period of 50 min and a burst size of approximately 100 phages. The phage DNA was resistant to digestion with restriction enzymes. Electron microscopy showed phiIF3 to be a member of the family Myoviridae. This is the first report of a generalized transducing phage able to infect Db11 and this phage will be a valuable tool for functional genomic analysis of the pathogen host.
A spectral dynamic stiffness method for free vibration analysis of plane elastodynamic problems
NASA Astrophysics Data System (ADS)
Liu, X.; Banerjee, J. R.
2017-03-01
A highly efficient and accurate analytical spectral dynamic stiffness (SDS) method for modal analysis of plane elastodynamic problems based on both plane stress and plane strain assumptions is presented in this paper. First, the general solution satisfying the governing differential equation exactly is derived by applying two types of one-dimensional modified Fourier series. Then the SDS matrix for an element is formulated symbolically using the general solution. The SDS matrices are assembled directly in a similar way to that of the finite element method, demonstrating the method's capability to model complex structures. Any arbitrary boundary conditions are represented accurately in the form of the modified Fourier series. The Wittrick-Williams algorithm is then used as the solution technique where the mode count problem (J0) of a fully-clamped element is resolved. The proposed method gives highly accurate solutions with remarkable computational efficiency, covering low, medium and high frequency ranges. The method is applied to both plane stress and plane strain problems with simple as well as complex geometries. All results from the theory in this paper are accurate up to the last figures quoted to serve as benchmarks.
Rekadwad, Bhagwan N; Khobragade, Chandrahasya N
2016-06-01
A total of 13 short DNA sequences of quality control strains (MCC 2052, MCC 2077, MCC 2078, MCC 2080, MCC 2309, MCC 2322, MCC 2408, MCC 2409, MCC 2412, MCC 2413, MCC 2415, MCC 2483 and MCC 2515) were retrieved from NCBI BioSample database and generated quick response (QR) codes for sequences. 16S rRNA was used for creation of Chaose Game representation (CGR), Chaose Game Representation of Frequencies (FCGR) and measurement of GC percentage. Digital data in the form of QR codes, CGR, FCGR and GC plot would be useful for identification, visual comparison and evaluation of newly isolated strains with quality control strains. The digital data of QR codes, CGR, FCGR and GC content all the quality control strains are made available to users through this paper. This generated digital data helps to evaluate and compare newly isolated strains, less laborious and avoid misinterpretation of newly isolated species.
Weber, Ulrike; Base, Eva; Ristl, Robin; Mora, Bruno
2015-08-01
Frequently used parameters for evaluation of left ventricular systolic function are load-sensitive. However, the impact of preload alterations on speckle-tracking echocardiographic parameters during anesthesia has not been validated. Therefore, two-dimensional (2D) speckle-tracking echocardiography radial strain (RS) was assessed during general anesthesia, simulating 3 different preload conditions. Single-center prospective observational study. University hospital. Thirty-three patients with normal left ventricular systolic function undergoing major surgery. Transgastric views of the midpapillary level of the left ventricle were acquired at 3 different positions. Fractional shortening (FS), fractional area change (FAC), and 2D speckle-tracking echocardiography RS were analyzed in the transgastric midpapillary view. Considerable correlation above 0.5 was found for FAC and FS in the zero and Trendelenburg positions (r = 0.629, r = 0.587), and for RS and FAC in the anti-Trendelenburg position (r = 0.518). In the repeated-measures analysis, significant differences among the values measured at the 3 positions were found for FAC and FS. For FAC, there were differences up to 2.8 percentage points between the anti-Trendelenburg position and the other 2 positions. For FS, only the difference between position zero and anti-Trendelenburg was significant, with an observed change of 1.66. Two-dimensional RS was not significantly different at all positions, with observed changes below 1 percentage point. Alterations in preload did not result in clinically relevant changes of RS, FS, or FAC. Observed changes for RS were smallest; however, the variation of RS was larger than that of FS or FAC. Copyright © 2015 Elsevier Inc. All rights reserved.
Tunaligil, Verda; Dokucu, Ali Ihsan; Erdogan, Mehmet Sarper
2016-07-01
This study investigated the impact of working for public versus private ambulance services in Turkey and elaborated on predictors of mental, physical, and emotional well-being in emergency medical technicians (EMT-Bs). In this observational cross-sectional study, an 81-question self-report survey was used to gather data about employee demographics, socioeconomic status, educational background, working conditions, and occupational health and workplace safety (OHS), followed by the 12-item General Health Questionnaire (GHQ-12), the Work-Related Strain Inventory (WRSI), and the Maslach Burnout Inventory (MBI) with three subscales: Emotional Exhaustion (MBI-EE), Depersonalization (MBI-DP), and Diminished Personal Accomplishment (MBI-PA). In 2011, 1,038 EMT-Bs worked for publicly operated and 483 EMT-Bs worked for privately owned ambulance services in Istanbul, Turkey, of which 606 (58.4%) and 236 (48.9%) participated in the study (overall participation rate = 55.4%), respectively. On all scales, differences between total mean scores in both sectors were statistically insignificant (p > .05). In the public sector, work locations, false accusations, occupational injuries and diseases, work-related permanent disabilities, and organizational support were found to significantly influence self-reported perceptions of well-being (p < .05). In the private sector, commute time to and from work (p < .05), false accusations (p < .05), vocational training and education (p < .05), informed career choices (p < .05), and work-related permanent disabilities (p < .05) were found to significantly influence self-reported perceptions of well-being. EMT-Bs were asked about aspects of their working lives that need improvement; priority expectations in the public and private sectors were higher earnings (17.5%; 16.7%) and better social opportunities (17.4%; 16.8%). Working conditions, vocational training, and OHS emerged as topics that merit priority attention.
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…
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…
Poudel, Pramod; Tashiro, Yukihiro; Sakai, Kenji
2016-01-01
Members of the genus Bacillus are considered to be both, among the best studied and most commonly used bacteria as well as the most still unexplored and the most wide-applicable potent bacteria because novel Bacillus strains are continuously being isolated and used in various areas. Production of optically pure l-lactic acid (l-LA), a feedstock for bioplastic synthesis, from renewable resources has recently attracted attention as a valuable application of Bacillus strains. l-LA fermentation by other producers, including lactic acid bacteria and Rhizopus strains (fungi) has already been addressed in several reviews. However, despite the advantages of l-LA fermentation by Bacillus strains, including its high growth rate, utilization of various carbon sources, tolerance to high temperature, and growth in simple nutritional conditions, it has not been reviewed. This review article discusses new findings on LA-producing Bacillus strains and compares them to other producers. The future prospects for LA-producing Bacillus strains are also discussed.
PLASTICITY AND NON-LINEAR ELASTIC STRAINS
conditions existing in plane waves in an extended medium to give the time rate of change of stress as a function of the time rate of change of strain, the stress invariants, the total strain and the plastic strain. (Author)
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.
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.
Cvorovic, Vojkan; Stankovic, Ivan; Panic, Milos; Stipac, Alja Vlahovic; Zivkovic, Aleksandra; Neskovic, Aleksandar N; Putnikovic, Biljana
2013-07-01
In cardiac arrest survivors, postresuscitation myocardial stunning usually presents as either global left ventricular dysfunction or regional dyssynergy including the various forms of stress cardiomyopathy, in which rare variants may be difficult to diagnose. We present a patient with cardiac arrest during general anesthesia, in whom speckle tracking-derived myocardial strain helped to distinguish between the inverted variant of stress cardiomyopathy and global postresuscitation myocardial stunning.
Empirical paths of poles to planes (eppps) constrain the kinematics of geological shear zones
NASA Astrophysics Data System (ADS)
Talbot, Christopher J.
2014-09-01
Ductile shear zones are tabular bodies of deformed rocks bound by less deformed wall rocks. This work introduces a simple empirical approach to analysing the 3D kinematics of shear zones. The orientations of pre-shear planar markers distorted across natural shear zones by local strains are systematically measured and plotted as poles on lower hemisphere equal area projections that constrain smooth empiricalpaths ofpoles toplanes (eppps). Such eppps recording local strain gradients are used to fix a reference frame to the plane of greatest shear in any homogeneous bulk strain. Assuming that space can be taken as a proxy for time, the curvatures of pre-shear planar markers across shear zones are interpreted as the records of the 3D bulk strain histories of shear zones. The sig- or zig-moidal symmetries of sheared markers record different amounts of the same general strain within the same overall movement pattern (i.e. in a constant flow field) whatever its geometry or history. In effect eppps represent the strain memories of shear zones with successively inward readings recording successively younger shearing. In planes other than the bulk XY, great circle eppps indicate simple shear while hyperbolic eppps indicate pure shear. Eppps for suites of shear zones in Proterozoic gneisses in Sweden exhibit the parabolic shapes indicative of pure rather than simple shear.
Fourier plane imaging microscopy
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.
Fixed Sagittal Plane Imbalance
Savage, Jason W.; Patel, Alpesh A.
2014-01-01
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. PMID:25396111
Fixed sagittal plane imbalance.
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.
Eight plane IPND mechanical testing.
Zhao, A.; Guarino, V.; Wood, K.; Nephew, T.; Ayres, D.; Lee, A.; High Energy Physics; FNAL
2008-03-18
A mechanical test of an 8 plane IPND mechanical prototype, which was constructed using extrusions from the testing/tryout of the 16 cell prototype extrusion die in Argonne National Laboratory, was conducted. There were 4 vertical and 4 horizontal planes in this 8 plane IPND prototype. Each vertical plane had four 16 cell extrusions, while each horizontal plane had six 16 cell extrusions. Each plane was glued together using the formulation of Devcon adhesive, Devcon 60. The vertical extrusions used in the vertical planes shares the same dimensions as the horizontal extrusions in the horizontal planes with the average web thickness of 2.1 mm and the average wall thickness of 3.1 mm. This mechanical prototype was constructed with end-seals on the both ends of the vertical extrusions. The gaps were filled with epoxy between extrusions and end-seals. The overall dimension of IPND is 154.8 by 103.1 by 21.7 inches with the weight of approximately 1200 kg, as shown in a figure. Two similar mechanical tests of 3 layer and 11 layer prototypes have been done in order to evaluate the strength of the adhesive joint between extrusions in the NOvA detector. The test showed that the IPND prototype was able to sustain under the loading of weight of itself and scintillator. Two FEA models were built to verify the measurement data from the test. The prediction from FEA slice model seems correlated reasonably well to the test result, even under a 'rough' estimated condition for the wall thickness (from an untuned die) and an unknown property of 'garage type' extrusion. A full size of FEA 3-D model also agrees very well with the test data from strain gage readings. It is worthy to point out that the stress distribution of the structure is predominantly determined by the internal pressure, while the buckling stability relies more on the loading weight from the extrusions themselves and scintillate. Results of conducted internal pressure tests, including 3- cell, 11-cell and the IPND
Pesta, Racheal; Peralta, Robert L; Novisky, Meghan A
2016-09-25
We know from the violence literature that a distinct sex disparity exists in the perpetration of other-directed violence (ODV). Some scholars suggest that this disparity is explained in part by gendered reactions to stress, strain, or violence victimization, in which males and females engage in different coping mechanisms, with males more likely to engage in ODV than females. Using a college sample, we investigate the behavioral responses of male and female victims of psychological intimate partner abuse. We find that although there is a sex disparity in the use of ODV as a coping mechanism, there is also a distinct gender orientation disparity. Our results indicate that victims who ascribe to a masculine identity are more likely than those of a feminine identity to engage in ODV, regardless of biological sex. These findings shed light on the impact of gender orientation as both a risk and protective factor in the use of ODV.
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.
Axial Plane Optical Microscopy
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
NASA Technical Reports Server (NTRS)
Morscher, Gregory N.; Pujar, Vijay V.
2008-01-01
In-plane tensile stress-strain, tensile creep, and after-creep retained tensile properties of melt-infiltrated SiC-SiC composites reinforced with different fiber types were evaluated with an emphasis on obtaining simple or first-order microstructural design guidelines for these in-plane mechanical properties. Using the mini-matrix approach to model stress-strain behavior and the results of this study, three basic general design criteria for stress and strain limits are formulated, namely a design stress limit, a design total strain limit, and an after-creep design retained strength limit. It is shown that these criteria can be useful for designing components for high temperature applications.
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.
Pastor, Géraldine; Jiménez-González, María; Plaza-García, Sandra; Beraza, Marta; Padro, Daniel; Ramos-Cabrer, Pedro; Reese, Torsten
2017-09-01
Differences in the cerebro-vasculature among strains as well as individual animals might explain variability in animal models and thus, a non-invasive method tailored to image cerebral vessel of interest with high signal to noise ratio is required. Experimentally, we describe a new general protocol of three-dimensional time-of-flight magnetic resonance angiography to visualize non-invasively the cerebral vasculature in 6 different rat strains. Flow compensated angiograms of Sprague Dawley, Wistar Kyoto, Lister Hooded, Long Evans, Fisher 344 and Spontaneous Hypertensive Rat strains were obtained without the use of contrast agents. At 11.7T using a repetition time of 60ms, an isotropic resolution of up to 62μm was achieved; total imaging time was 98min for a 3D data set. The visualization of the cerebral arteries was improved by removing extra-cranial vessels prior to the calculation of maximum intensity projection to obtain the angiograms. Ultimately, we demonstrate that the newly implemented method is also suitable to obtain angiograms following middle cerebral artery occlusion, despite the presence of intense vasogenic edema 24h after reperfusion. The careful selection of the excitation profile and repetition time at a higher static magnetic field allowed an increase in spatial resolution to reliably detect of the hypothalamic artery, the anterior choroidal artery as well as arterial branches of the peri-amygdoidal complex and the optical nerve in six different rat strains. MR angiography without contrast agent can be utilized to study cerebro-vascular abnormalities in various animal models. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.
Transverse plane motion at the ankle joint.
Nester, Christopher J; Findlow, Andrew F; Bowker, Peter; Bowden, Peter D
2003-02-01
The ankle is often considered to have little or no capacity to move in the transverse plane. This is clear in the persistent concept that it is the role of the subtalar joint to accommodate the transverse plane motion of the leg while the foot remains in a fixed transverse plane position on the floor. We present data from noninvasive in vivo study of the ankle subtalar complex during standing internal and external rotation of the leg and study of the ankle subtalar complex during walking. These data reinforce the results of cadaver study and invasive in vivo study of the ankle/subtalar complex. We suggest that the ankle is capable of considerable movement in the transverse plane (generally greater than 15 degrees) and that its role in the mechanism that allows the foot to remain in a fixed transverse plane position on the floor while the leg rotates in the transverse plane, is not simply the transfer of the transverse plane moment to the subtalar joint, but is accommodation of some of the necessary movement.
Precise measurement of planeness.
Schulz, G; Schwider, J
1967-06-01
Interference methods are reviewed-particularly those developed at the German Academy of Sciences in Berlin-with which the deviations of an optically flat surface from the ideal plane can be measured with a high degree of exactness. One aid to achieve this is the relative methods which measure the differences in planeness between two surfaces. These are then used in the absolute methods which determine the absolute planeness of a surface. This absolute determination can be effected in connection with a liquid surface, or (as done by the authors) only by suitable evaluation of relative measurements between unknown plates in various positional combinations. Experimentally, one uses two- or multiple-beam interference fringes of equal thickness(1) or of equal inclination. The fringes are observed visually, scanned, or photographed, and in part several wavelengths or curves of equal density (Aquidensiten) are employed. The survey also brings the following new methods: a relative method, where, with the aid of fringes of superposition, the fringe separation is subdivided equidistantly thus achieving an increase of measuring precision, and an absolute method which determines the deviations of a surface from ideal planeness along arbitrary central sections, without a liquid surface, from four relative interference photographs.
ERIC Educational Resources Information Center
Greenman, Geri
2001-01-01
Describes an assignment that was used in an advanced drawing class in which the students created self-portraits, breaking up their images using planes and angles to suggest their bone structure. Explains that the students also had to include three realistic portions in their drawings. (CMK)
Causal inheritence in plane wave quotients
Hubeny, Veronika E.; Rangamani, Mukund; Ross, Simon F.
2003-11-24
We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality.
Space plane navigation simulation
NASA Astrophysics Data System (ADS)
Matsushima, Koichi; Murata, Masaaki; Shingu, Hirokimi; Shimizu, Tetsuo; Mikami, Tatsuo; Hashida, Yoshikazu
A simulation program for a future Japanese space-plane (SP) considered for development is presented along with the results of the analysis of a candidate navigation configuration, focused on the terminal area energy management phase and the approach/landing phase of SP. The guidance laws and aerodynamic parameters which are applied to the program for the analysis are modeled using the laws and parameters of the U.S. Space Suttle, assuming typical values for the accuracy of sensors.
1989-03-01
Th usr a toente aninteer a thca sms b esta 1 Fp-ocsing 2. Enter P1 values, lwgt, ldig - > 9 Table I give us proper values. Table 1. PARAMETER TABLE...necessary and identify by block number) In this thesis a control systems analysis package is developed using parameter plane methods. It is an interactive...designer is able to choose values of the parameters which provide a good compromise between cost and dynamic behavior. 20 Distribution Availability of
NASA Technical Reports Server (NTRS)
Munk, Max M
1923-01-01
This report deals with the calculation of the equilibrium, statistical stability, and damping of the tail plane. The author has simplified the present theory of longitudinal stability for the particular purpose of obtaining one definite coefficient characteristics of the effect of the tail plane. This coefficient is obtained by substituting certain aerodynamic characteristics and some dimensions of the airplane in a comparatively simple mathematical expression. Care has been taken to confine all aerodynamical information necessary for the calculation of the coefficient to the well-known curves representing the qualities of the wing section. This is done by making use of the present results of modern aerodynamics. All formulas and relations necessary for the calculation are contained in the paper. They give in some cases only an approximation of the real values. An example of calculation is added in order to illustrate the application of the method. The coefficient indicates not only whether the effect of the tail plane is great enough, but also whether it is not too great. It appears that the designer has to avoid a certain critical length of the fuselage, which inevitably gives rise to periodical oscillations of the airplane. The discussion also shows the way and in what direction to carry out experimental work.
Graf, A. ); Hosford, W. . Dept. of Materials Science and Engineering)
1993-11-01
The effect of changing strain paths on forming limits of aluminum alloy 2008-T4 has been investigated by determining forming limit diagrams (FLDs) after prestraining. Sheets were prestrained to several levels in uniaxial, biaxial, and plane-strain tension parallel and perpendicular to the prior rolling direction (RD). Abrupt changes in the strain path can be used to increase the forming limits. Prestraining in biaxial tension generally lowers the forming limits for the entire FLD, whereas prestraining in uniaxial tension raises the limits on the right-hand side of the FLD without much effect on the left-hand side. Prestraining in plane-strain tension raises both sides away from the minimum. Finally, it was found that after prestraining, the amount of the additional plane-strain deformation possible depends on the effective strain during prestrain.
Björk, G R; Kjellin-Stråby, K
1978-01-01
A general method for the isolation of mutants of Escherichia coli that are defective in RNA modification is described. The method is based on the fact that RNA with specific undermodifications accumulates under nonpermissive growth conditions and that such a defect can be detected by remodification either in vivo at permissive conditions or in vitro. The method provides a means by which to study mutations affecting essential modification reactions. The usefulness of the method was demonstrated by the isolation of two rRNA and two tRNA methylation defective mutants. Both rRNA mutants accept methyl groups into their 23S rRNA in vitro. Analyses of in vitro methylated 23S rRNA from one of the mutants revealed the presence of several methylated nucleosides, of which 6-methyladenosine was the most abundant (40% of recovered radioactivity). In 23S rRNA from the other mutant, the only product formed in vitro was 5-methylcytidine. The tRNA mutants are characterized in the accompanying paper. Images PMID:342494
High temperature strain gage apparent strain compensation
NASA Technical Reports Server (NTRS)
Holmes, Harlan K.; Moore, T. C., Sr.
1992-01-01
Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.
Optical strain measuring techniques for high temperature tensile testing
NASA Technical Reports Server (NTRS)
Gyekenyesi, John Z.; Hemann, John H.
1987-01-01
A number of optical techniques used for the analysis of in-plane displacements or strains are reviewed. The application would be for the high temperature, approximately 1430 C (2600 F), tensile testing of ceramic composites in an oxidizing atmosphere. General descriptions of the various techniques and specifics such as gauge lengths and sensitivities are noted. Also, possible problems with the use of each method in the given application are discussed.
Functional Aesthetic Occlusal Plane (FAOP)
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
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.
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.
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.
NASA Technical Reports Server (NTRS)
Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.
1989-01-01
In response to the tremendous growth in the development of advanced materials, such as fiber-reinforced plastic (FRP) composite materials, a new numerical method is developed to analyze and predict the time-dependent properties of these materials. Basic concepts in viscoelasticity, laminated composites, and previous viscoelastic numerical methods are presented. A stable numerical method, called the nonlinear differential equation method (NDEM), is developed to calculate the in-plane stresses and strains over any time period for a general laminate constructed from nonlinear viscoelastic orthotropic plies. The method is implemented in an in-plane stress analysis computer program, called VCAP, to demonstrate its usefulness and to verify its accuracy. A number of actual experimental test results performed on Kevlar/epoxy composite laminates are compared to predictions calculated from the numerical method.
Focal plane polarimeter design
McClelland, J.B.
1983-10-12
Measurement of polarization transfer or so-called triple-scattering parameters have been made recently for proton-nucleon scattering at TRIUMF, SIN, and LAMPF using carbon polarimeters and have been essential in determining the proton-nucleon amplitudes up to 800 MeV. An extension to the case is described where the scattered proton polarization is analyzed after passage through some type of spectrometer. Most of the experience with this type of focal plane polarimeter (FPP) has been gained in the field of proton-nucleus scattering at intermediate energies but is certainly not confined to such specific cases. The salient features of an FPP are emphasized by describing a minimal system which includes all the necessary components then go on to a more complete system. 10 references. (WHK)
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.
Focal Plane Metrology for the LSST Camera
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.
Thin-film light-intensity measurement strain-analysis technique.
NASA Technical Reports Server (NTRS)
Williams, J. G.
1972-01-01
The optical response to loading of a thin metallic film deposited on a low-modulus structural substrate is studied theoretically and experimentally. Two types of optical properties called total and central-image transmittance (or reflectance) are shown to be related to the mechanical state of the substrate. Empirical optical-mechanical relationships are proposed between these optical properties and the substrate strain field of a general plane-stress problem. A technique based on wrinkle and microfracture patterns is described for determining principal directions of strain. Experimental results for uniaxially loaded specimens show that it is possible to obtain a nearly linear relationship between transmittance and strain for certain materials combinations.
NASA Technical Reports Server (NTRS)
Dillon, O. W., Jr.
1985-01-01
An investigation of the blowing up of UK numerical results for the inplane stress calculations for silicon ribbon is presented. The inplane stress that exists in a thin plate is governed by two general equations of equilibrium and compatibility.
Bradburne, Christopher E.; Verhoeven, Anne B.; Manyam, Ganiraju C.; Chaudhry, Saira A.; Chang, Eddie L.; Thach, Dzung C.; Bailey, Charles L.; van Hoek, Monique L.
2013-01-01
Pneumonic tularemia is caused by inhalation of Francisella tularensis, one of the most infectious microbes known. We wanted to study the kinetics of the initial and early interactions between bacterium and host cells in the lung. To do this, we examined the infection of A549 airway epithelial cells with the live vaccine strain (LVS) of F. tularensis. A549 cells were infected and analyzed for global transcriptional response at multiple time points up to 16 h following infection. At 15 min and 2 h, a strong transcriptional response was observed including cytoskeletal rearrangement, intracellular transport, and interferon signaling. However, at later time points (6 and 16 h), very little differential gene expression was observed, indicating a general suppression of the host response consistent with other reported cell lines and murine tissues. Genes for macropinocytosis and actin/cytoskeleton rearrangement were highly up-regulated and common to the 15 min and 2 h time points, suggesting the use of this method for bacterial entry into cells. We demonstrate macropinocytosis through the uptake of FITC-dextran and amiloride inhibition of Francisella LVS uptake. Our results suggest that macropinocytosis is a potential mechanism of intracellular entry by LVS and that the host cell response is suppressed during the first 2–6 h of infection. These results suggest that the attenuated Francisella LVS induces significant host cell signaling at very early time points after the bacteria's interaction with the cell. PMID:23322778
Khrustalev, Vladislav Victorovich; Ghaznavi-Rad, Ehsanollah; Neela, Vasanthakumari; Shamsudin, Mariana-Nor; Amouzandeh-Nobaveh, Alireza; Barkovsky, Eugene Victorovich
2013-11-01
Fifteen sequences with stop codons have been obtained in the course of standard methicillin-resistant Staphylococcus aureus (MRSA) spa typing. In nine of those sequences, stop codons occurred due to nonsense G-T and A-T transversions. G-T transversions would appear to be frequent in the spa gene, mostly due to symmetric mutational AT-pressure in the whole S. aureus genome and due to replication-associated mutational pressure characteristic of lagging strands of the "chromosome". A-T transversions would appear to be frequent in the spa gene mostly due to transcription-associated mutational pressure. Relative to other S. aureus genes, short repeats in spa are enriched by nonsense sites for G-T and A-T transversions; the probability of being nonsense for A-T transversion is high in that part of spa coding region. 13 out of 15 (87%) of the sequences with stop codons were obtained from strains isolated from patients with generalized S. aureus infection. Truncation of spa at its C-terminus is predicted to result in a protein that possesses functional IgG binding domains unable to be linked to the cell wall. This is discussed in light of the known fact that extracellular spa is a strong virulence factor involved in immune evasion. Copyright © 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
NASA Technical Reports Server (NTRS)
Oliver, D. S.; Aldrich, R. E.; Krol, F. T.
1972-01-01
An electrically addressed liquid crystal Fourier plane filter capable of real time optical image processing is described. The filter consists of two parts: a wedge filter having forty 9 deg segments and a ring filter having twenty concentric rings in a one inch diameter active area. Transmission of the filter in the off (transparent) state exceeds fifty percent. By using polarizing optics, contrast as high as 10,000:1 can be achieved at voltages compatible with FET switching technology. A phenomenological model for the dynamic scattering is presented for this special case. The filter is designed to be operated from a computer and is addressed by a seven bit binary word which includes an on or off command and selects any one of the twenty rings or twenty wedge pairs. The overall system uses addressable latches so that once an element is in a specified state, it will remain there until a change of state command is received. The drive for the liquid crystal filter is ? 30 V peak at 30 Hz to 70 Hz. These parameters give a rise time for the scattering of 20 msec and a decay time of 80 to 100 msec.
Plane impact response of PBX 9501 below 2 GPA
Dick, J.J.; Martinez, A.R.; Hixson, R.S.
1998-12-31
The plane impact response of PBX 9501 was measured below 2 GPa using a light-gas gun facility. Time-resolved wave profiles were obtained in a state of uniaxial strain for impact stresses between 0.3 to 1.2 GPa. The dynamic strength of PBX 9501 was measured at high strain rates in both compression and tension. The Hugoniot equation of state was measured.
In-plane and out-of-plane motions of the human tympanic membrane
Khaleghi, Morteza; Cheng, Jeffrey Tao; Furlong, Cosme; Rosowski, John J.
2016-01-01
Computer-controlled digital holographic techniques are developed and used to measure shape and four-dimensional nano-scale displacements of the surface of the tympanic membrane (TM) in cadaveric human ears in response to tonal sounds. The combination of these measurements (shape and sound-induced motions) allows the calculation of the out-of-plane (perpendicular to the surface) and in-plane (tangential) motion components at over 1 000 000 points on the TM surface with a high-degree of accuracy and sensitivity. A general conclusion is that the in-plane motion components are 10–20 dB smaller than the out-of-plane motions. These conditions are most often compromised with higher-frequency sound stimuli where the overall displacements are smaller, or the spatial density of holographic fringes is higher, both of which increase the uncertainty of the measurements. The results are consistent with the TM acting as a Kirchhoff–Love's thin shell dominated by out-of-plane motion with little in-plane motion, at least with stimulus frequencies up to 8 kHz. PMID:26827009
Out-of-plane chiral domain wall spin-structures in ultrathin in-plane magnets
Chen, Gong; Kang, Sang Pyo; Ophus, Colin; ...
2017-05-19
Chiral spin textures in ultrathin films, such as skyrmions or chiral domain walls, are believed to offer large performance advantages in the development of novel spintronics technologies. While in-plane magnetized films have been studied extensively as media for current- and field-driven domain wall dynamics with applications in memory or logic devices, the stabilization of chiral spin textures in in-plane magnetized films has remained rare. Here we report a phase of spin structures in an in-plane magnetized ultrathin film system where out-of-plane spin orientations within domain walls are stable. Moreover, while domain walls in in-plane films are generally expected to bemore » non-chiral, we show that right-handed spin rotations are strongly favoured in this system, due to the presence of the interfacial Dzyaloshinskii-Moriya interaction. These results constitute a platform to explore unconventional spin dynamics and topological phenomena that may enable high-performance in-plane spin-orbitronics devices.« less
Out-of-plane chiral domain wall spin-structures in ultrathin in-plane magnets
NASA Astrophysics Data System (ADS)
Chen, Gong; Kang, Sang Pyo; Ophus, Colin; N'diaye, Alpha T.; Kwon, Hee Young; Qiu, Ryan T.; Won, Changyeon; Liu, Kai; Wu, Yizheng; Schmid, Andreas K.
2017-05-01
Chiral spin textures in ultrathin films, such as skyrmions or chiral domain walls, are believed to offer large performance advantages in the development of novel spintronics technologies. While in-plane magnetized films have been studied extensively as media for current- and field-driven domain wall dynamics with applications in memory or logic devices, the stabilization of chiral spin textures in in-plane magnetized films has remained rare. Here we report a phase of spin structures in an in-plane magnetized ultrathin film system where out-of-plane spin orientations within domain walls are stable. Moreover, while domain walls in in-plane films are generally expected to be non-chiral, we show that right-handed spin rotations are strongly favoured in this system, due to the presence of the interfacial Dzyaloshinskii-Moriya interaction. These results constitute a platform to explore unconventional spin dynamics and topological phenomena that may enable high-performance in-plane spin-orbitronics devices.
Out-of-plane chiral domain wall spin-structures in ultrathin in-plane magnets
Chen, Gong; Kang, Sang Pyo; Ophus, Colin; N'Diaye, Alpha T.; Kwon, Hee Young; Qiu, Ryan T.; Won, Changyeon; Liu, Kai; Wu, Yizheng; Schmid, Andreas K.
2017-01-01
Chiral spin textures in ultrathin films, such as skyrmions or chiral domain walls, are believed to offer large performance advantages in the development of novel spintronics technologies. While in-plane magnetized films have been studied extensively as media for current- and field-driven domain wall dynamics with applications in memory or logic devices, the stabilization of chiral spin textures in in-plane magnetized films has remained rare. Here we report a phase of spin structures in an in-plane magnetized ultrathin film system where out-of-plane spin orientations within domain walls are stable. Moreover, while domain walls in in-plane films are generally expected to be non-chiral, we show that right-handed spin rotations are strongly favoured in this system, due to the presence of the interfacial Dzyaloshinskii–Moriya interaction. These results constitute a platform to explore unconventional spin dynamics and topological phenomena that may enable high-performance in-plane spin-orbitronics devices. PMID:28524875
Out-of-plane chiral domain wall spin-structures in ultrathin in-plane magnets.
Chen, Gong; Kang, Sang Pyo; Ophus, Colin; N'Diaye, Alpha T; Kwon, Hee Young; Qiu, Ryan T; Won, Changyeon; Liu, Kai; Wu, Yizheng; Schmid, Andreas K
2017-05-19
Chiral spin textures in ultrathin films, such as skyrmions or chiral domain walls, are believed to offer large performance advantages in the development of novel spintronics technologies. While in-plane magnetized films have been studied extensively as media for current- and field-driven domain wall dynamics with applications in memory or logic devices, the stabilization of chiral spin textures in in-plane magnetized films has remained rare. Here we report a phase of spin structures in an in-plane magnetized ultrathin film system where out-of-plane spin orientations within domain walls are stable. Moreover, while domain walls in in-plane films are generally expected to be non-chiral, we show that right-handed spin rotations are strongly favoured in this system, due to the presence of the interfacial Dzyaloshinskii-Moriya interaction. These results constitute a platform to explore unconventional spin dynamics and topological phenomena that may enable high-performance in-plane spin-orbitronics devices.
Absence of rippling in graphene under biaxial tensile strain
NASA Astrophysics Data System (ADS)
Rakshit, Bipul; Mahadevan, Priya
2010-10-01
Recent experiments [C. H. Lui, L. Liu, K. F. Mak, G. W. Flynn, and T. F. Heinz, Nature (London) 462, 339 (2009)10.1038/nature08569] on graphene grown on ultraflat substrates have found no rippling in graphene when subject to temperature cycling. Unsupported/unstrained films of graphene as well as films grown on various substrates on the other hand have been found to show rippling effects. As graphene grown on a substrate is invariably strained, we examine the behavior of the out-of-plane acoustic-phonon mode with biaxial tensile strain. This mode is generally associated with the rippling of graphene. We find that it can be fit to a relation of the form w2=Ak4+Bk2 , where w and k are the frequency and wave vector, respectively. The coefficient A is found to show a weak dependence on strain while B is found to increase linearly with strain. The strain-induced hardening explains the absence of rippling in graphene subject to biaxial strain. In addition, we find that graphene when subject to a biaxial tensile strain is found to undergo a structural transition with the mode at K going soft at a strain percentage of 15%.
2006-04-19
This view of the ringed planet shows its tilt relative to the plane of its orbit around the Sun. The planet tilts nearly 27 degrees relative to the ecliptic plane giving rise to seasons in which the rings shadow each hemisphere in its respective winter
Cleveland, Michael J.; Hecht, Michael L.
2013-01-01
Latent growth curve modeling was used to test four hypotheses. First, this study hypothesized that acculturation-related variables (e.g., Mexican-heritage youth’s country of origin, time spent in the U.S., and language preference with family and friends) would be associated with initial levels of perceived discrimination. Guided by general strain theory (GST), this study then posed a second hypothesis: Initial levels of perceived discrimination would be indirectly related to initial levels of substance use through initial levels of acculturation stress. Third, this study hypothesized that changes in perceived discrimination would be indirectly related to changes in substance use through changes in acculturation stress. As a fourth hypothesis, it was postulated that initial levels of perceived discrimination would be indirectly related to changes in substance use through changes in acculturation stress. Mexican-heritage youth (N=1,106) from 29 schools in Phoenix, AZ completed surveys at six waves from 5th through 8th grades. In partial support of the first hypothesis, more time spent in the U.S. and speaking English with friends were associated with lower levels of perceived discrimination. The second hypothesis was not supported. Initial levels of perceived discrimination were positively associated with initial levels of acculturation stress; however, this association was not found between initial levels of acculturation stress and substance use. The third and fourth hypotheses were supported, which buttressed predictions derived from GST. Both initial levels and increases in perceived discrimination were indirectly related to increases in substance use through increases in acculturation stress. PMID:20490921
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.
A Plane Strain Plasticity Analysis of the Anchor Pullout Problem.
1981-01-01
recurrence formulas: 11 X. . t z i- l’j-zi’j -l +X W j- tan (O ii _j -l+ ) Xi -lW tan (e i l jIt] tan (8i , ) +)-tan -i_ ,-() (8a) Zi~ i_ 1 j + (x i ’ x...priori (although for computational purposes a and S are assumed). Therefore, zone OBD should be solved as a Cauchy problem. 20 2. In cohesionless...Therefore, the analytical I VI".I II I.. 28 approach of Nowatzki and Karafiath (1981) was extended to the problem at hand, with the rigid body surface
Validation of a Scaled Plane Strain Hypervelocity Gouging Model
2006-03-01
These are the Analytic Equation of State (ANEOS), and SNL- SESAME , a tabular EOS . 42 In this work, materials are modeled using the SESAME EOS ... eos * Eq Of State 81 MAT1 SES STEEL_V300 * Sesame Eq of State...mass of material with the internal energy Eo . Because the mass in front of the shock was assumed stationary, this also happens to be the internal
Auditory spatial resolution in horizontal, vertical, and diagonal planes
NASA Astrophysics Data System (ADS)
Grantham, D. Wesley; Hornsby, Benjamin W. Y.; Erpenbeck, Eric A.
2003-08-01
Minimum audible angle (MAA) and minimum audible movement angle (MAMA) thresholds were measured for stimuli in horizontal, vertical, and diagonal (60°) planes. A pseudovirtual technique was employed in which signals were recorded through KEMAR's ears and played back to subjects through insert earphones. Thresholds were obtained for wideband, high-pass, and low-pass noises. Only 6 of 20 subjects obtained wideband vertical-plane MAAs less than 10°, and only these 6 subjects were retained for the complete study. For all three filter conditions thresholds were lowest in the horizontal plane, slightly (but significantly) higher in the diagonal plane, and highest for the vertical plane. These results were similar in magnitude and pattern to those reported by Perrott and Saberi [J. Acoust. Soc. Am. 87, 1728-1731 (1990)] and Saberi and Perrott [J. Acoust. Soc. Am. 88, 2639-2644 (1990)], except that these investigators generally found that thresholds for diagonal planes were as good as those for the horizontal plane. The present results are consistent with the hypothesis that diagonal-plane performance is based on independent contributions from a horizontal-plane system (sensitive to interaural differences) and a vertical-plane system (sensitive to pinna-based spectral changes). Measurements of the stimuli recorded through KEMAR indicated that sources presented from diagonal planes can produce larger interaural level differences (ILDs) in certain frequency regions than would be expected based on the horizontal projection of the trajectory. Such frequency-specific ILD cues may underlie the very good performance reported in previous studies for diagonal spatial resolution. Subjects in the present study could apparently not take advantage of these cues in the diagonal-plane condition, possibly because they did not externalize the images to their appropriate positions in space or possibly because of the absence of a patterned visual field.
A theoretical investigation of orientation relationships and transformation strains in steels.
Koumatos, K; Muehlemann, A
2017-03-01
The identification of orientation relationships (ORs) plays a crucial role in the understanding of solid phase transformations. In steels, the most common models of ORs are the ones by Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS). The defining feature of these and other OR models is the matching of directions and planes in the parent face-centred cubic γ phase to ones in the product body-centred cubic/tetragonal α/α' phase. In this article a novel method that identifies transformation strains with ORs is introduced and used to develop a new strain-based approach to phase-transformation models in steels. Using this approach, it is shown that the transformation strains that leave a close-packed plane in the γ phase and a close-packed direction within that plane unrotated are precisely those giving rise to the NW and KS ORs when a cubic product phase is considered. Further, it is outlined how, by choosing different pairs of unrotated planes and directions, other common ORs such as the ones by Pitsch and Greninger-Troiano can be derived. One of the advantages of our approach is that it leads to a natural generalization of the NW, KS and other ORs for different ratios of tetragonality r of the product body-centred tetragonal α' phase. These generalized ORs predict a sharpening of the transformation textures with increasing tetragonality and are thus in qualitative agreement with experiments on steels with varying alloy concentration.
Anisotropic strain and phonon deformation potentials in GaN
Darakchieva, V.; Arwin, H.; Paskov, P. P.; Monemar, B.; Paskova, T.; Hommel, D.; Schubert, M.; Heuken, M.; Off, J.; Scholz, F.; Haskell, B. A.; Fini, P. T.; Speck, J. S.; Nakamura, S.
2007-05-15
We report optical phonon frequency studies in anisotropically strained c-plane- and a-plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E{sub 1}(TO), E{sub 1}(LO), and E{sub 2} phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c{sub E{sub 1}}{sub (TO)}, c{sub E{sub 1}}{sub (LO)}, and c{sub E{sub 2}} are determined. A distinct correlation between anisotropic strain and the A{sub 1}(TO) and E{sub 1}(LO) frequencies of a-plane GaN films reveals the a{sub A{sub 1}}{sub (TO)}, b{sub A{sub 1}}{sub (TO)}, a{sub E{sub 1}}{sub (LO)}, and b{sub E{sub 1}}{sub (LO)} phonon deformation potentials. The a{sub A{sub 1}}{sub (TO)} and b{sub A{sub 1}}{sub (TO)} are found to be in very good agreement with previous results from Raman experiments [V. Yu. Davydov et al., J. Appl. Phys. 82, 5097 (1997)]. Our a{sub A{sub 1}}{sub (TO)} and a{sub E{sub 1}}{sub (LO)} phonon deformation potentials agree well with recently reported theoretical estimations [J.-M. Wagner and F. Bechstedt, Phys. Rev. B 66, 115202 (2002)], while b{sub A{sub 1}}{sub (TO)} and b{sub E{sub 1}}{sub (LO)} are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented.
Hamiltonian maps in the complex plane
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.
Plane reconstruction ultrasound tomography device
Hassler, D.
1984-10-23
An ultrasound tomography device for scanning an object under examination from a plurality of directions. Coronal slice images of the plane areas near or at the female breast wall are obtained. Ultrasound lobes from ultrasound transducers are electronically directed or mechanically positioned to obliquely strike the coronal slice located at or near the breast wall. A full image of the coronal slice plane is reconstructed through section by section combination of the images obtained from the several ultrasound lobes.
Röthlisberger Channel Model with Anti-Plane Shear Loading Superposed on In-Plane Compression
NASA Astrophysics Data System (ADS)
Fernandes, M. C.; Meyer, C. R.; Rice, J. R.
2014-12-01
The Röthlisberger channel (R-channel) is a commonly adopted model that balances creep closure by Nye 2D in-plane straining, driven by the ice overburden pressure, against the melt rate from viscous energy dissipation in turbulent flow within the channel. Perol and Rice (AGU abstr. C11B-0677, 2011; JGR 2014 in review) and Suckale et al. (JGR F003008, 2014) have conjectured that these R-Channels may exist at the beds of rapidly straining West Antarctic Ice Stream shear margins. That is expected as a result of melt generation and drainage from forming temperate ice, and the channels may interact through the bed hydrology to partially stabilize the shear margin against lateral expansion. However, at those locations the overburden stresses, driving in-plane flow, are supplemented by substantial anti-plane shear stresses. Similarly, R-channels in mountain glaciers are also subject to both in-plane and anti-plane stresses. These channels usually form in the downstream direction, where anti-plane shear effects arise horizontally from drag at lateral moraines and vertically from the downslope gravity component. Here we examine how superposed anti-plane loading can alter results of the Nye solution for a 2D R-channel. We use a combination of perturbation analyses and finite element methods, varying the amount of applied anti-plane stress. A closed-form solution is derived for imposing a small anti-plane perturbation, which has no effect at linear order on the Nye closure rate. Such effects become strong at more substantial perturbations, and the inplane stress and strain fields are then significantly altered from the Nye solution. We further extend our model to compute channel size in terms of the external stressing and flow rate. Understanding the effect of the ice flow on channel size and formation is important to subglacial hydrology, as well as a potentially vital component for our understanding of the formation and motion of ice streams found in West Antarctica.
NASA Technical Reports Server (NTRS)
Houseman, G.; England, P.
1986-01-01
The present investigation has the objective to perform numerical experiments on a rheologically simple continuum model for the continental lithosphere. It is attempted to obtain a better understanding of the dynamics of continental deformation. Calculations are presented of crustal thickness distributions, stress, strain, strain rate fields, latitudinal displacements, and finite rotations, taking into account as basis a model for continental collision which treats the litoshphere as a thin viscous layer subject to indenting boundary conditions. The results of this paper support the conclusions of England and McKenzie (1982) regarding the role of gravity in governing the deformation of a thin viscous layer subject to indenting boundary conditions. The results of the experiments are compared with observations of topography, stress and strain rate fields, and palaeomagnetic latitudinal displacements in Asia.
The relationship between strain geometry and geometrically necessary dislocations
NASA Astrophysics Data System (ADS)
Hansen, Lars; Wallis, David
2016-04-01
The kinematics of past deformations are often a primary goal in structural analyses of strained rocks. Details of the strain geometry, in particular, can help distinguish hypotheses about large-scale tectonic phenomena. Microstructural indicators of strain geometry have been heavily utilized to investigate large-scale kinematics. However, many of the existing techniques require structures for which the initial morphology is known, and those structures must undergo the same deformation as imposed macroscopically. Many deformed rocks do not exhibit such convenient features, and therefore the strain geometry is often difficult (if not impossible) to ascertain. Alternatively, crystallographic textures contain information about the strain geometry, but the influence of strain geometry can be difficult to separate from other environmental factors that might affect slip system activity and therefore the textural evolution. Here we explore the ability for geometrically necessary dislocations to record information about the deformation geometry. It is well known that crystallographic slip due to the motion of dislocations yields macroscopic plastic strain, and the mathematics are established to relate dislocation glide on multiple slip systems to the strain tensor of a crystal. This theoretical description generally assumes that dislocations propagate across the entire crystal. However, at any point during the deformation, dislocations are present that have not fully transected the crystal, existing either as free dislocations or as dislocations organized into substructures like subgrain boundaries. These dislocations can remain in the lattice after deformation if the crystal is quenched sufficiently fast, and we hypothesize that this residual dislocation population can be linked to the plastic strain geometry in a quantitative manner. To test this hypothesis, we use high-resolution electron backscatter diffraction to measure lattice curvatures in experimentally deformed
NASA Technical Reports Server (NTRS)
1997-01-01
multi-phase research program for tailplane icing (TIP II) to develop test methodologies and tailplane performance and handling qualities evaluation tools. The main objectives of this new NASA/Industry/Academia collaborative research programs were: (1) define and evaluate a sub-scale wind tunnel test methodology for determining tailplane performance degradation due to icing. (2) develop an experimental database of tailplane aerodynamic performance with and without ice contamination for a range of tailplane configurations. Wind tunnel tests were planned with representative general aviation aircraft, i.e., the Learjet 45, and a twin engine low speed aircraft. This report summarizes the research performed during the first year of the study, and outlines the work tasks for the second year.
2013-01-01
Background Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences. Results Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations. Conclusions This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness. PMID:24195767
Determination of the in-plane components of motion in a Lamb wave from single-axis laser vibrometry.
Rajic, Nik; Rosalie, Cedric; Norman, Patrick; Davis, Claire
2014-06-01
A method is proposed for determining in-plane components of motion in a Lamb wave from laser vibrometer measurements of surface motion out of plane. The approach relies on a frequency domain transformation that assumes knowledge only of the plate thickness and the bulk wave speeds. An outline of the relevant theory is followed by several validation case studies that generally affirm a useful level of accuracy and robust performance across a relatively wide frequency-thickness product range. In a comparison to the two-angle vibrometry approach, the proposed method is shown to be simpler to implement and to yield estimates with a consistently higher signal to noise ratio. The approach is then used to furnish estimates of the in-plane strains in Lamb waves propagating in an aluminum plate at frequencies below the first cut-off. These estimates are compared to strain measurements obtained from an adhesively bonded fiber Bragg grating. The agreement is shown to be excellent overall with an average discrepancy of less than 6%; however, systematic errors of twice that amount were recorded in the low-frequency-thickness product regime. These low-frequency discrepancies are not consistent with known sources of experimental error and cannot be explained by shear-lag theory.
Models for elastic shells with incompatible strains
Lewicka, Marta; Mahadevan, L.; Pakzad, Mohammad Reza
2014-01-01
The three-dimensional shapes of thin lamina, such as leaves, flowers, feathers, wings, etc., are driven by the differential strain induced by the relative growth. The growth takes place through variations in the Riemannian metric given on the thin sheet as a function of location in the central plane and also across its thickness. The shape is then a consequence of elastic energy minimization on the frustrated geometrical object. Here, we provide a rigorous derivation of the asymptotic theories for shapes of residually strained thin lamina with non-trivial curvatures, i.e. growing elastic shells in both the weakly and strongly curved regimes, generalizing earlier results for the growth of nominally flat plates. The different theories are distinguished by the scaling of the mid-surface curvature relative to the inverse thickness and growth strain, and also allow us to generalize the classical Föppl–von Kármán energy to theories of prestrained shallow shells. PMID:24808750
The Schwinger Model on the Null-Plane
NASA Astrophysics Data System (ADS)
Casana, R.; Pimentel, B. M.; Zambrano, G. E. R.
We study the Schwinger Model on the null-plane using the Dirac method for constrained systems. The fermion field is analyzed using the natural null-plane projections coming from the γ-algebra and it is shown that the fermionic sector of the Schwinger Model has only second class constraints. However, the first class constraints are exclusively of the bosonic sector. Finally, we establish the graded Lie algebra between the dynamical variables, via generalized Dirac bracket in the null-plane gauge, which is consistent with every constraint of the theory.
The Principles of Cutting-Plane Theory: Part I.
The paper develops a fundamental result, which reveals a construction through which all valid cutting -planes for integer programming, and other...fundamental result is simply a characterization theorem and does not reveal directly how to obtain cuts . The paper proceeds beyond this theorem, to develop...how the general theory is adequate to account for all the well-known cutting -planes of the literature, and how the process of isolating the
Stresses and strains in thick perforated orthotropic plates
A. Alshaya; John Hunt; R. Rowlands
2016-01-01
Stress and strain concentrations and in-plane and out-of-plane stress constraint factors associated with a circular hole in thick, loaded orthotropic composite plates are determined by three-dimensional finite element method. The plate has essentially infinite in-plane geometry but finite thickness. Results for Sitka Spruce wood are emphasized, although some for carbon...
Simulation Exploration through Immersive Parallel Planes: Preprint
Brunhart-Lupo, Nicholas; Bush, Brian W.; Gruchalla, Kenny; Smith, Steve
2016-03-01
We present a visualization-driven simulation system that tightly couples systems dynamics simulations with an immersive virtual environment to allow analysts to rapidly develop and test hypotheses in a high-dimensional parameter space. To accomplish this, we generalize the two-dimensional parallel-coordinates statistical graphic as an immersive 'parallel-planes' visualization for multivariate time series emitted by simulations running in parallel with the visualization. In contrast to traditional parallel coordinate's mapping the multivariate dimensions onto coordinate axes represented by a series of parallel lines, we map pairs of the multivariate dimensions onto a series of parallel rectangles. As in the case of parallel coordinates, each individual observation in the dataset is mapped to a polyline whose vertices coincide with its coordinate values. Regions of the rectangles can be 'brushed' to highlight and select observations of interest: a 'slider' control allows the user to filter the observations by their time coordinate. In an immersive virtual environment, users interact with the parallel planes using a joystick that can select regions on the planes, manipulate selection, and filter time. The brushing and selection actions are used to both explore existing data as well as to launch additional simulations corresponding to the visually selected portions of the input parameter space. As soon as the new simulations complete, their resulting observations are displayed in the virtual environment. This tight feedback loop between simulation and immersive analytics accelerates users' realization of insights about the simulation and its output.
Brotman, David; Zhang, Ziheng; Sampath, Smita
2013-05-01
Noninvasive quantification of regional left ventricular rotation may improve understanding of cardiac function. Current methods used to quantify rotation typically acquire data on a set of prescribed short-axis slices, neglecting effects due to through-plane myocardial motion. We combine principles of slice-following tagged imaging with harmonic phase analysis methods to account for through-plane motion in regional rotation measurements. We compare rotation and torsion measurements obtained using our method to those obtained from imaging datasets acquired without slice-following. Our results in normal volunteers demonstrate differences in the general trends of average and regional rotation-time plots in midbasal slices and the rotation versus circumferential strain loops. We observe substantial errors in measured peak average rotation of the order of 58% for basal slices (due to change in the pattern of the curve), -6.6% for midventricular slices, and -8.5% for apical slices; and an average error in base-to-apex torsion of 19% when through-plane motion is not considered. This study concludes that due to an inherent base-to-apex gradient in rotation that exists in the left ventricular, accounting for through-plane motion is critical to the accuracy of left ventricular rotation quantification.
Brotman, David; Zhang, Ziheng; Sampath, Smita
2012-01-01
Non-invasive quantification of regional left ventricular (LV) rotation may improve understanding of cardiac function. Current methods employed to quantify rotation typically acquire data on a set of prescribed short-axis slices, neglecting effects due to through-plane myocardial motion. We combine principles of slice-following tagged imaging with harmonic phase analysis methods to account for through-plane motion in regional rotation measurements. We compare rotation and torsion measurements obtained using our method to those obtained from imaging datasets acquired without slice-following. Our results in normal volunteers demonstrate differences in the general trends of average and regional rotation-time plots in mid-basal slices, and of the rotation versus circumferential strain loops. We observe substantial errors in measured peak average rotation of the order of 58% for basal slices (due to change in the pattern of the curve), −6.6% for mid-ventricular slices, and −8.5% for apical slices; and an average error in base-to-apex torsion of 19% when through-plane motion is not considered. This study concludes that due to an inherent base-to-apex gradient in rotation that exists in the LV, accounting for through-plane motion is critical to the accuracy of LV rotation quantification. PMID:22700308
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.
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.
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.
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.
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.
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.
Aranda, Agustín; del Olmo Ml, Marcel lí
2003-06-01
One of the stress conditions that yeast may encounter is the presence of acetaldehyde. In a previous study we identified that, in response to this stress, several HSP genes are induced that are also involved in the response to other forms of stress. Aldehyde dehydrogenases (ALDH) play an important role in yeast acetaldehyde metabolism (e.g. when cells are growing in ethanol). In this work we analyse the expression of the genes encoding these enzymes (ALD) and also the corresponding enzymatic activities under several growth conditions. We investigate three kinds of yeast strains: laboratory strains, strains involved in the alcoholic fermentation stage of wine production and flor yeasts (responsible for the biological ageing of sherry wines). The latter are very important to consider because they grow in media containing high ethanol concentrations, and produce important amounts of acetaldehyde. Under several growth conditions, further addition of acetaldehyde or ethanol in flor yeasts induced the expression of some ALD genes and led to an increase in ALDH activity. This result is consistent with their need to obtain energy from ethanol during biological ageing processes. Our data also suggest that post-transcriptional and/or post-translational mechanisms are involved in regulating the activity of these enzymes. Finally, analyses indicate that the Msn2/4p and Hsf1p transcription factors are necessary for HSP26, ALD2/3 and ALD4 gene expression under acetaldehyde stress, while PKA represses the expression of these genes.
Computing Displacements And Strains From Video Images
NASA Technical Reports Server (NTRS)
Russell, Samuel S.; Mcneill, Stephen R.; Lansing, Matthew D.
1996-01-01
Subpixel digital video image correlation (SDVIC) technique for measuring in-plane displacements on surfaces of objects under loads, without contact. Used for analyses of experimental research specimens or actual service structures of virtually any size or material. Only minimal preparation of test objects needed, and no need to isolate test objects from minor vibrations or fluctuating temperatures. Technique implemented by SDVIC software, producing color-graduated, full-field representations of in-plane displacements and partial derivatives with respect to position along both principal directions in each image plane. From representations, linear strains, shear strains, and rotation fields determined. Written in C language.
Auxetic behavior and acoustic properties of microstructured piezoelectric strain sensors
NASA Astrophysics Data System (ADS)
De Bellis, Maria Laura; Bacigalupo, Andrea
2017-08-01
The use of multifunctional composite materials adopting piezo-electric periodic cellular lattice structures with auxetic elastic behavior is a recent and promising solution in the design of piezoelectric sensors. In the present work, periodic anti-tetrachiral auxetic lattice structures, characterized by different geometries, are taken into account and the mechanical and piezoelectrical response are investigated. The equivalent piezoelectric properties are obtained adopting a first order computational homogenization approach, generalized to the case of electro-mechanical coupling, and various polarization directions are adopted. Two examples of in-plane and out-of-plane strain sensors are proposed as design concepts. Moreover, a piezo-elasto-dynamic dispersion analysis adopting the Floquet-Bloch decomposition is performed. The acoustic behavior of the periodic piezoelectric material with auxetic topology is studied and possible band gaps are detected.
Planes of satellite galaxies and the cosmic web
NASA Astrophysics Data System (ADS)
Libeskind, Noam I.; Hoffman, Yehuda; Tully, R. Brent; Courtois, Helene M.; Pomarède, Daniel; Gottlöber, Stefan; Steinmetz, Matthias
2015-09-01
Recent observational studies have demonstrated that the majority of satellite galaxies tend to orbit their hosts on highly flattened, vast, possibly corotating planes. Two nearly parallel planes of satellites have been confirmed around the M31 galaxy and around the Centaurus A galaxy, while the Milky Way also sports a plane of satellites. It has been argued that such an alignment of satellites on vast planes is unexpected in the standard Λ cold dark matter (ΛCDM) model of cosmology if not even in contradiction to its generic predictions. Guided by ΛCDM numerical simulations, which suggest that satellites are channelled towards hosts along the axis of the slowest collapse as dictated by the ambient velocity shear tensor, we re-examine the planes of local satellites systems within the framework of the local shear tensor derived from the Cosmicflows-2 data set. The analysis reveals that the Local Group and Centaurus A reside in a filament stretched by the Virgo cluster and compressed by the expansion of the Local Void. Four out of five thin planes of satellite galaxies are indeed closely aligned with the axis of compression induced by the Local Void. Being the less massive system, the moderate misalignment of the Milky Way's satellite plane can likely be ascribed to its greater susceptibility to tidal torques, as suggested by numerical simulations. The alignment of satellite systems in the local Universe with the ambient shear field is thus in general agreement with predictions of the ΛCDM model.
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.…
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.…
Plane stress analysis of wood members using isoparametric finite elements, a computer program
Gary D. Gerhardt
1983-01-01
A finite element program is presented which computes displacements, strains, and stresses in wood members of arbitrary shape which are subjected to plane strain/stressloading conditions. This report extends a program developed by R. L. Taylor in 1977, by adding both the cubic isoparametric finite element and the capability to analyze nonisotropic materials. The...
NASA Astrophysics Data System (ADS)
Cébron, Guillaume; Dahlqvist, Antoine; Gabriel, Franck
2017-09-01
The master field is the large N limit of the Yang-Mills measure on the Euclidean plane. It can be viewed as a non-commutative process indexed by loops on the plane. We construct and study generalized master fields, called free planar Markovian holonomy fields which are versions of the master field where the law of a simple loop can be as more general as it is possible. We prove that those free planar Markovian holonomy fields can be seen as well as the large N limit of some Markovian holonomy fields on the plane with unitary structure group.
Tomek, Markus B; Janesch, Bettina; Maresch, Daniel; Windwarder, Markus; Altmann, Friedrich; Messner, Paul; Schäffer, Christina
2017-03-16
The occurrence of nonulosonic acids in bacteria is wide-spread and linked to pathogenicity. However, the knowledge of cognate nonulosonic acid transferases is scarce. In the periodontopathogen Tannerella forsythia, several proposed virulence factors carry strain-specifically either a pseudaminic or a legionaminic acid derivative as terminal sugar on an otherwise structurally identical, protein-bound oligosaccharide. This study aims to shed light on the transfer of either nonulosonic acid derivative on a proximal N-acetylmannosaminuronic acid residue within the O-glycan structure, exemplified with the bacterium's abundant S-layer glycoproteins. Bioinformatic analyses provided the candidate genes Tanf_01245 (strain ATCC 43037) and TFUB4_00887 (strain UB4), encoding a putative pseudaminic and a legionaminic acid derivative transferase, respectively. These transferases have identical C-termini and contain motifs typical of glycosyltransferases (DXD) and bacterial sialyltransferases (D/E-D/E-G and HP). They share homology to type B glycosyltransferases and TagB, an enzyme catalyzing glycerol transfer to an N-acetylmannosamine residue in teichoic acid biosynthesis. Analysis of a cellular pool of nucleotide-activated sugars confirmed the presence of the CMP-activated nonulosonic acid derivatives, which are most likely serving as substrates for the corresponding transferase. Single gene knock-out mutants targeted at either transferase were analyzed for S-layer O-glycan composition by ESI-MS, confirming the loss of the nonulosonic acid derivative. Cross-complementation of the mutants with the nonnative nonulosonic acid transferase was not successful indicating high stringency of the enzymes. This study identified plausible candidates for a pseudaminic and a legionaminic acid derivative transferase; these may serve as valuable tools for engineering of novel sialoglycoconjugates.
NASA Astrophysics Data System (ADS)
Moreau, Magnus; Marthinsen, Astrid; Selbach, Sverre M.; Tybell, Thomas
2017-02-01
The structural and electronic response of LaAl O3 to biaxial strain in the (111) plane is studied by density functional theory (DFT) and compared with strain in the (001) plane and isostatic strain. For (111) strain, in-plane rotations are stabilized by compressive strain and out-of-plane rotations by tensile strain. This is an opposite splitting of the modes compared with (001) strain. Furthermore, for compressive (111) strain, in-plane rotations are degenerate with respect to the rotation axis, giving rise to Goldstone-like modes. We rationalize these changes in octahedral rotations by analyzing the VA/VB polyhedral volume ratios. Finally, we investigate how strain affects the calculated band gap, and find a 28% difference between the strain planes under 4% tension. This effect is attributed to different A-site dodecahedral crystal field splitting for (001) and (111) strains.
Granular materials: constitutive equations and strain localization
NASA Astrophysics Data System (ADS)
Anand, L.; Gu, C.
2000-08-01
Strain localization into shear bands is commonly observed in natural soil masses, as well as in human-built embankments, footings, retaining walls and other geotechnical structures. Numerical predictions for the process of shear band formation are critically dependent on the constitutive equations employed. In this paper, the plane strain "double-shearing" constitutive model (e.g., Spencer, A.J.M., 1964. A theory of the kinematics of ideal soils under plane strain conditions. Journal of the Mechanics and Physics of Solids 12, 337-351; Spencer, A.J.M., 1982, Deformation of ideal granular materials. In: Hopkins, H.G., Sewell, M.J. (Eds.), Mechanics of Solids. Pergamon Press, Oxford and New York, pp. 607-652; Mehrabadi, M.M., Cowin, S.C., 1978. Initial planar deformation of dilatant granular materials. Journal of the Mechanics and Physics of Solids 26, 269-284; Nemat-Nasser, S., Mehrabadi, M.M., Iwakuma, T. 1981. On certain macroscopic and microscopic aspects of plastic flow of ductile materials. In: Nemat-Nasser, S. (Ed.), Three-dimensional Constitutive Relations and Ductile Fracture. North-Holland, Amsterdam, pp. 157-172; Anand, L., 1983. Plane deformations of ideal granular materials. Journal of the Mechanics and Physics of Solids 31, 105-122) is generalized to three dimensions including the effects of elastic deformation and pre-peak behavior. The constitutive model is implemented in a finite element program and is used to predict the formation of shear bands in plane strain compression, and plane strain cylindrical cavity expansion. The predictions from the model are shown to be in good quantitative agreement with the recent experiments of Han, C., Drescher, A., (1993. Shear bands in biaxial tests on dry coarse sand. Soils and Foundations 33, 118-132) and Alsiny, H., Vardoulakis, I., Drescher, A., (1992. Deformation localization in cavity inflation experiments on dry sand. Geotechnique 42, 395-410) on a dry sand. The constitutive model is also used to predict the
On the Influence of Strain-Path Changes on Fracture.
1986-08-01
BEFORE COMPLETING FORM I. REPORT NUMBER 2 GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER Report No. 1 4 7,/f2. ? 4. TITLE (and Subtitle) S. TYPE OF...uniaxial and equibiaxial tension are shown to have a large effect on plane-strain ductility. Data for titanium sheets, both with and without hydrides, show...that a significant ductility enhancement occurs at a final strain state of plane-strain tension following multi-stage deformation sequences comprised
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.
Symmetry in finite phase plane
NASA Astrophysics Data System (ADS)
Zak, J.
2010-03-01
The known symmetries in one-dimensional systems are inversion and translations. These symmetries persist in finite phase plane, but a novel symmetry arises in view of the discrete nature of the coordinate xi and the momentum pi : xi and pi can undergo permutations. Thus, if xi assumes M discrete values, i = 0, 1,2,..., M - 1, a permutation will change the order of the set x0,x1,..., xM-1 into a new ordered set. Such a symmetry element does not exist for a continuous x-coordinate in an infinite phase plane. Thus, in a finite phase plane, translations can be replaced by permutations. This is also true for the inversion operator. The new permutation symmetry has been used for the construction of conjugate representations and for the splitting of the M-dimensional vector space into independent subspaces. This splitting is exhaustive in the sense that if M = iMi with Mi being prime numbers, the M-dimensional space splits into M1,M2,...Mn-dimensional independent subspaces. It is shown that following this splitting one can design new potentials with appropriate constants of motion. A related problem is the Weyl-Heisenberg group in the M-dimensional space which turns into a direct product of its subgroups in the Mi-dimensional subspaces. As an example we consider the case of M = 8.
Orbital Space Plane (OSP) Program
NASA Technical Reports Server (NTRS)
McKenzie, Patrick M.
2003-01-01
Lockheed Martin has been an active participant in NASA's Space Launch Initiative (SLI) programs over the past several years. SLI, part of NASA's Integrated Space Transportation Plan (ISTP), was restructured in November of 2002 to focus the overall theme of safer, more afford-able space transportation along two paths - the Orbital Space Plane Program and the Next Generation Launch Technology programs. The Orbital Space Plane Program has the goal of providing rescue capability from the International Space Station by 2008 and transfer capability for crew (and limited cargo) by 2012. The Next Generation Launch Technology program is combining research and development efforts from the 2nd Generation Reusable Launch Vehicle (2GRLV) program with cutting-edge, advanced space transportation programs (previously designated 3rd Generation) into one program aimed at enabling safe, reliable, cost-effective reusable launch systems by the middle of the next decade. Lockheed Martin is one of three prime contractors working to bring Orbital Space Plane system concepts to a system definition level of maturity by December of 2003. This paper and presentation will update the international community on the progress of the' OSP program, from an industry perspective, and provide insights into Lockheed Martin's role in enabling the vision of a safer, more affordable means of taking people to and from space.
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
Blass, J.J.
1982-01-01
An improved multiaxial fatigue failure criterion was developed based on the results of combined axial-torsional strain cycling tests of AISI 304 and 2-1/4 Cr-1 Mo steel conducted at 538/sup 0/C (1000/sup 0/F). The formulation of this criterion involves the shear and normal components of inelastic strain range on the planes of maximum inelastic shear strain range. Optimum values of certain parameters contained in the formulation were obtained for each material by the method of least squares. The ability of this criterion to correlate the test results was compared with that of the usual (Mises) equivalent inelastic strain range criterion. An improved definition of equivalent inelastic strain range resulting from these considerations was used to generalize the theory of Strain Range Partitioning to multiaxial stress-strain conditions and was also applied to the linear summation of creep and fatigue damage.
Projecting diffusion along the normal bundle of a plane curve
Valero-Valdés, Carlos; Herrera-Guzmán, Rafael
2014-05-15
The purpose of this paper is to provide new formulas for the effective diffusion coefficient of a generalized Fick-Jacob's equation obtained by projecting the two-dimensional diffusion equation along the normal directions of an arbitrary curve on the plane.
Projecting diffusion along the normal bundle of a plane curve
NASA Astrophysics Data System (ADS)
Valero-Valdés, Carlos; Herrera-Guzmán, Rafael
2014-05-01
The purpose of this paper is to provide new formulas for the effective diffusion coefficient of a generalized Fick-Jacob's equation obtained by projecting the two-dimensional diffusion equation along the normal directions of an arbitrary curve on the plane.
Intersection of Three Planes Revisited--An Algebraic Approach
ERIC Educational Resources Information Center
Trenkler, Götz; Trenkler, Dietrich
2017-01-01
Given three planes in space, a complete characterization of their intersection is provided. Special attention is paid to the case when the intersection set does not exist of one point only. Besides the vector cross product, the tool of generalized inverse of a matrix is used extensively.
Intersection of Three Planes Revisited--An Algebraic Approach
ERIC Educational Resources Information Center
Trenkler, Götz; Trenkler, Dietrich
2017-01-01
Given three planes in space, a complete characterization of their intersection is provided. Special attention is paid to the case when the intersection set does not exist of one point only. Besides the vector cross product, the tool of generalized inverse of a matrix is used extensively.
Kauffman bracket of plane curves
NASA Astrophysics Data System (ADS)
Chmutov, S.; Goryunov, V.
1996-12-01
We lower the Kauffman bracket for links in a solid torus (see [16]) to generic plane fronts. It turns out that the bracket can be entirely defined in terms of a front itself without using the Legendrian lifting. We show that all the coefficients of the lowered bracket are in fact Vassilev type invariants of Arnold's J +-theory [3, 4]. We calculate their weight systems. As a corollary we obtain that the first coefficient is essentially the quantum deformation of the Bennequin invariant introduced recently by M. Polyak [19].
SNAP Satellite Focal Plane Development
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.
NASA Astrophysics Data System (ADS)
Soler, José M.; Williams, Arthur R.
1990-11-01
Results are presented that demonstrate the effectiveness of a calculational method of electronic-structure theory. The method combines the power (tractable basis-set size) and flexibility (transition and first-row elements) of the augmented-plane-wave method with the computational efficiency of the Car-Parrinello method of molecular dynamics and total-energy minimization. Equilibrium geometry and vibrational frequencies in agreement with experiment are presented for Si, to demonstrate agreement with existing methods and for Cu, N2, and H2O to demonstrate the broader applicability of the approach.
Orbital Space Plane Cost Credibility
NASA Technical Reports Server (NTRS)
Creech, Steve
2003-01-01
NASA's largest new start development program is the Orbital Space Plane (OSP) Program. The program is currently in the formulation stage. One of the critical issues to be resolved, prior to initiating full-scale development, is establishing cost credibility of NASA s budget estimates for development, production, and operations of the OSP. This paper will discuss the processes, tools, and methodologies that NASA, along with its industry partners, are implementing to assure cost credibility for the OSP program. Results of benchmarking of current tools and the development of new cost estimating capabilities and approaches will be discussed.
NASA Astrophysics Data System (ADS)
Dineva, Petia; Rangelov, Tsviatko
2016-12-01
Elastic wave scattering by cracks at macro- and nano-scale in anisotropic plane under conditions of plane strain is studied in this work. Furthermore, time-harmonic loads due to incident plane longitudinal P- or shear SV- wave are assumed to hold. In a subsequent step, the elastodynamic fundamental solution for general anisotropic continua derived in closed-form via the Radon transform is implemented in a numerical scheme based on the traction boundary integral equation method (BIEM). The surface elasticity effect in the case of nano-crack is taken into consideration via non-classical boundary condition along the crack surface proposed by Gurtin and Murdoch [1]. The numerical results obtained herein reveal substantial differences between anisotropic materials containing a macro- and a nano-crack in terms of their dynamic stress response, where the latter case demonstrates clearly the strong influence of the size-effects. Finally, these types of examples serve to illustrate the present approach and to show its potential for evaluating the stress concentration fields (SCF) inside cracked nanocomposites. The obtained results concern the reliability and safety of the advancing nanomaterials.
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
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
Solution of the plane stochastic creep boundary value problem
NASA Astrophysics Data System (ADS)
Kovalenko, L. V.; Popov, N. N.; Radchenko, V. P.
2009-01-01
The solution of the non-linear stochastic boundary-value problem of the creep of a thin plate in a plane stress state when the elastic strains are small and can be neglected is presented. The plate material is stochastically inhomogeneous so that the stress and strain tensors are random functions of the coordinates. The constitutive creep relation, taken as in non-linear viscous flow theory, is formulated in a stochastic form. Using the perturbation method, the non-linear stochastic problem is reduced to a system of three linear partial differential equations in the fluctuations of the stress tensor and, then, changing by implementing the stress function, to a differential equation, the solution of which is represented in the form of the sum of two series. The first series is the solution far from the boundary of the plate, ignoring edge effects, and the second is the solution in the boundary layer, and its terms rapidly decay as the distance from the boundary of the plate increases. The stretching of a stochastically inhomogeneous half-plane in the direction of two mutually orthogonal axes is considered as an example. The stress concentration in the boundary of the half-plane is investigated. It is shown that the spread of the stresses in the surface layer, the width of which depends on the degree of non-linearity of the material, can be much greater than in the deep layers.
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;
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.
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.
Image plane sweep volume illumination.
Sundén, Erik; Ynnerman, Anders; Ropinski, Timo
2011-12-01
In recent years, many volumetric illumination models have been proposed, which have the potential to simulate advanced lighting effects and thus support improved image comprehension. Although volume ray-casting is widely accepted as the volume rendering technique which achieves the highest image quality, so far no volumetric illumination algorithm has been designed to be directly incorporated into the ray-casting process. In this paper we propose image plane sweep volume illumination (IPSVI), which allows the integration of advanced illumination effects into a GPU-based volume ray-caster by exploiting the plane sweep paradigm. Thus, we are able to reduce the problem complexity and achieve interactive frame rates, while supporting scattering as well as shadowing. Since all illumination computations are performed directly within a single rendering pass, IPSVI does not require any preprocessing nor does it need to store intermediate results within an illumination volume. It therefore has a significantly lower memory footprint than other techniques. This makes IPSVI directly applicable to large data sets. Furthermore, the integration into a GPU-based ray-caster allows for high image quality as well as improved rendering performance by exploiting early ray termination. This paper discusses the theory behind IPSVI, describes its implementation, demonstrates its visual results and provides performance measurements.
Singularities from colliding plane gravitational waves
NASA Astrophysics Data System (ADS)
Tipler, Frank J.
1980-12-01
A simple geometrical argument is given which shows that a collision between two plane gravitational waves must result in singularities. The argument suggests that these singularities are a peculiar feature of plane waves, because singularities are also a consequence of a collision between self-gravitating plane waves of other fields with arbitrarily small energy density.
The universal plane method for calculating the dimensions of heliostats
NASA Astrophysics Data System (ADS)
Perres, L. B.; Baum, I. V.
It is pointed out that heliostat dimensions are crucial in ensuring that sunlight is properly reflected during the day in solar furnaces and solar power stations. In determining these dimensions, allowance must be made for changes in the sun's position during the day, changes which depend on the latitude of the installation. To construct unique algorithms for calculating the dimensions, a procedure involving general concepts must be formulated and this formulation introduces a universal frame of reference. An example of this which has attracted considerable interest involves a flat round receiver that is parallel either to the horizontal plane or to the universal plane considered here.
Material mechanical characterization method for multiple strains and strain rates
Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli
2016-01-19
A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.
NASA Technical Reports Server (NTRS)
1995-01-01
HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.
Smov Baseline Focal Plane Check
NASA Astrophysics Data System (ADS)
Gilmozzi, Roberto
1994-01-01
This test will be executed during the period after the servicing mission and before the extension of the COSTAR assembly. Its purpose is to verify that the FOS, HRS, and FOC focal planes have not been altered by the activities performed by Story and the Astronauts during the servicing mission. A large unknown deviation in aperture position would severly impact subsequent COSTAR alignment activities. If this test reveals a deviation, we may be able to compensate for any offsets prior to the complex and delicate COSTAR alignment calibrations. This enhanced version of the Heptathlon is designed to verify course alignments and measure relative aperture positions to within a few arcsecs. SPECIAL REQUIREMENTS: ***This test uses pre-servicing parameters for HRS, FOS, and FOC and the Cycle 4 parameters for WFPC2.*** ***This test requires special alignment and special guide stars.** ***This test requires special commanding for telemetry setups.**
Thermodynamics of black plane solution
NASA Astrophysics Data System (ADS)
Rodrigues, Manuel E.; Jardim, Deborah F.; Houndjo, Stéphane J. M.; Myrzakulov, Ratbay
2013-11-01
We obtain a new phantom black plane solution in D of the Einstein-Maxwell theory coupled with a cosmological constant. We analyse their basic properties, as well as its causal structure, and obtain the extensive and intensive thermodynamic variables, as well as the specific heat and the first law. Through the specific heat and the so-called geometric methods, we analyse in detail their thermodynamic properties, the extreme and phase transition limits, as well as the local and global stabilities of the system. The normal case is shown with an extreme limit and the phantom one with a phase transition only for null mass, which is physically inaccessible. The systems present local and global stabilities for certain values of the entropy density with respect to the electric charge, for the canonical and grand canonical ensembles.
NASA Astrophysics Data System (ADS)
McCormick, Andrew; Young, Bruce A.; Mahadevan, L.
2012-02-01
We develop a new computational model of elastic rods, taking into account shear and full rotational dynamics, as well as friction, adhesion, and collision. This model is used to study the movement of snakes in different environments. By applying different muscular activation patterns to the snake, we observe many different patterns of motion, from planar undulation to sudden strikes. Many of the most interesting behaviors involve the snake rising out of the horizontal plane in the vertical direction. Such behaviors include a sand snake sidewinding over the hot desert sand and a cobra rearing up into a defensive striking position. Experimental videos of live snakes are analyzed and compared with computational results. We identify and explain a new form of movement previously unobserved: ``collateral locomotion.''
Simple plane wave implementation for photonic crystal calculations.
Guo, Shangping; Albin, Sacharia
2003-01-27
A simple implementation of plane wave method is presented for modeling photonic crystals with arbitrary shaped 'atoms'. The Fourier transform for a single 'atom' is first calculated either by analytical Fourier transform or numerical FFT, then the shift property is used to obtain the Fourier transform for any arbitrary supercell consisting of a finite number of 'atoms'. To ensure accurate results, generally, two iterating processes including the plane wave iteration and grid resolution iteration must converge. Analysis shows that using analytical Fourier transform when available can improve accuracy and avoid the grid resolution iteration. It converges to the accurate results quickly using a small number of plane waves. Coordinate conversion is used to treat non-orthogonal unit cell with non-regular 'atom' and then is treated by standard numerical FFT. MATLAB source code for the implementation requires about less than 150 statements, and is freely available at http://www.lions.odu.edu/~sguox002.
NASA Astrophysics Data System (ADS)
Kim, Wansun; Lee, Inhwa; Kim, Dong Yoon; Yu, Youn-Yeol; Jung, Hae-Yoon; Kwon, Seyeoul; Park, Weon Seo; Kim, Taek-Soo
2017-05-01
To protect brittle layers in organic photovoltaic devices, the mechanical neutral plane strategy can be adopted through placing the brittle functional materials close to the neutral plane where stress and strain are zero during bending. However, previous research has been significantly limited in the location and number of materials to protect through using a single neutral plane. In this study, multiple neutral planes are generated using low elastic modulus adhesives and are controlled through quantitative analyses in order to protect the multiple brittle materials at various locations. Moreover, the protection of multiple brittle layers at various locations under both concave and convex bending directions is demonstrated. Multilayer structures that have soft adhesives are further analyzed using the finite element method analysis in order to propose guidelines for structural design when employing multiple neutral planes.
Off-plane anastigmatic imaging in Offner spectrometers.
Prieto-Blanco, Xesús; González-Nuñez, Héctor; de la Fuente, Raúl
2011-11-01
In this paper, the imaging performance of an Offner concentric imaging spectrometer is analyzed when the spectrometer entrance slit is disposed arbitrarily on the plane that is parallel to the grating grooves and contains the common center of curvature. Astigmatism-corrected designs are obtained for off-plane incidence on the grating if one point on the slit is located on the Rowland circle of the primary mirror. In this case, the combined system of primary mirror plus diffraction grating provides two astigmatic line images oriented parallel and orthogonal to the plane of diffraction, with the former located on the same plane as the slit. Consequently, these images can be brought to a single focus on this plane by the tertiary mirror if its radius of curvature is chosen properly. In addition, coma aberration is simultaneously removed. These results can be applied to the design of two-mirror or three-mirror spectrometers, generalizing the concept of the best imaging circle and providing solutions to get anastigmatic imaging for two object points and two wavelengths.
In-plane heterostructures of Sb/Bi with high carrier mobility
NASA Astrophysics Data System (ADS)
Zhao, Pei; Wei, Wei; Sun, Qilong; Yu, Lin; Huang, Baibiao; Dai, Ying
2017-06-01
In-plane two-dimensional (2D) heterostructures have been attracting public attention due to their distinctive properties. However, the pristine materials that can form in-plane heterostructures are reported only for graphene, hexagonal BN, transition-metal dichalcogenides. It will be of great significance to explore more suitable 2D materials for constructing such ingenious heterostructures. Here, we demonstrate two types of novel seamless in-plane heterostructures combined by pristine Sb and Bi monolayers by means of first-principle approach based on density functional theory. Our results indicate that external strain can serve as an effective strategy for bandgap engineering, and the transition from semiconductor to metal occurs when a compressive strain of -8% is applied. In addition, the designed heterostructures possess direct band gaps with high carrier mobility (˜4000 cm2 V-1 s-1). And the mobility of electrons and holes have huge disparity along the direction perpendicular to the interface of Sb/Bi in-plane heterostructures. It is favorable for carriers to separate spatially. Finally, we find that the band edge positions of Sb/Bi in-plane heterostructures can meet the reduction potential of hydrogen generation in photocatalysis. Our results not only offer alternative materials to construct versatile in-plane heterostructures, but also highlight the applications of 2D in-plane heterostructures in diverse nanodevices and photocatalysis.
In-plane heterostructures of Sb/Bi with high carrier mobility.
Zhao, Pei; Wei, Wei; Sun, Qilong; Yu, Lin; Huang, Baibiao; Dai, Ying
2017-06-23
In-plane two-dimensional (2D) heterostructures have been attracting public attention due to their distinctive properties. However, the pristine materials that can form in-plane heterostructures are reported only for graphene, hexagonal BN, transition-metal dichalcogenides. It will be of great significance to explore more suitable 2D materials for constructing such ingenious heterostructures. Here, we demonstrate two types of novel seamless in-plane heterostructures combined by pristine Sb and Bi monolayers by means of first-principle approach based on density functional theory. Our results indicate that external strain can serve as an effective strategy for bandgap engineering, and the transition from semiconductor to metal occurs when a compressive strain of -8% is applied. In addition, the designed heterostructures possess direct band gaps with high carrier mobility (∼4000 cm(2) V(-1) s(-1)). And the mobility of electrons and holes have huge disparity along the direction perpendicular to the interface of Sb/Bi in-plane heterostructures. It is favorable for carriers to separate spatially. Finally, we find that the band edge positions of Sb/Bi in-plane heterostructures can meet the reduction potential of hydrogen generation in photocatalysis. Our results not only offer alternative materials to construct versatile in-plane heterostructures, but also highlight the applications of 2D in-plane heterostructures in diverse nanodevices and photocatalysis.
Strain engineering of Kapitza resistance in few-layer graphene.
Chen, Jie; Walther, Jens H; Koumoutsakos, Petros
2014-02-12
We demonstrate through molecular dynamics simulations that the Kapitza resistance in few-layer graphene (FLG) can be controlled by applying mechanical strain. For unstrained FLG, the Kapitza resistance decreases with the increase of thickness and reaches an asymptotic value of 6 × 10(-10) m(2)K/W at a thickness about 16 nm. Uniaxial cross-plane strain is found to increase the Kapitza resistance in FLG monotonically, when the applied strain varies from compressive to tensile. Moreover, uniaxial strain couples the in-plane and out-of-plane strain/stress when the surface of FLG is buckled. We find that with a compressive cross-plane stress of 2 GPa, the Kapitza resistance is reduced by about 50%. On the other hand it is almost tripled with a tensile cross-plane stress of 1 GPa. Remarkably, compressive in-plane strain can either increase or reduce the Kapitza resistance, depending on the specific way it is applied. Our study suggests that graphene can be exploited for both heat dissipation and insulation through strain engineering.
Service life of finishes on smooth-planed and saw-textured western redcedar bevel siding
R. Sam Williams; William C. Feist
2007-01-01
The performance of 35 finishes (clear water-repellent Preservatives; lightly pigmented, water-repellent preservatives; semitransparent stains; solid-color stains; and paints) applied to newly planed vertical-grained; factory-planed, flat-grained; or saw-textured, vertical-grained western redcedar bevel siding was evaluated for cracking, erosion, and general appearance...
Tilted planes in 3D image analysis
NASA Astrophysics Data System (ADS)
Pargas, Roy P.; Staples, Nancy J.; Malloy, Brian F.; Cantrell, Ken; Chhatriwala, Murtuza
1998-03-01
Reliable 3D wholebody scanners which output digitized 3D images of a complete human body are now commercially available. This paper describes a software package, called 3DM, being developed by researchers at Clemson University and which manipulates and extracts measurements from such images. The focus of this paper is on tilted planes, a 3DM tool which allows a user to define a plane through a scanned image, tilt it in any direction, and effectively define three disjoint regions on the image: the points on the plane and the points on either side of the plane. With tilted planes, the user can accurately take measurements required in applications such as apparel manufacturing. The user can manually segment the body rather precisely. Tilted planes assist the user in analyzing the form of the body and classifying the body in terms of body shape. Finally, titled planes allow the user to eliminate extraneous and unwanted points often generated by a 3D scanner. This paper describes the user interface for tilted planes, the equations defining the plane as the user moves it through the scanned image, an overview of the algorithms, and the interaction of the tilted plane feature with other tools in 3DM.
Cope, Steven M; Tailor, Dishant; Nagorski, Richard W
2011-01-21
The induction of strain in carbocycles, thereby increasing the amount of s-character in the C-H bonds and the acidity of these protons, has been probed with regard to its effect on the rate constants for the enolization of cyclobutanone. The second-order rate constants for the general base-catalyzed enolization of cyclobutanone have been determined for a series of 3-substituted quinuclidine buffers in D(2)O at 25 °C, I = 1.0 M (KCl). The rate constants for enolization were determined by following the extent of deuterium incorporation (up to ∼30% of the first α-proton) into the α-position, as a function of time. The observed pseudo-first-order rate constants correlated to the [basic form] of the buffer and yielded the second-order rate constants for the general base-catalyzed enolization of cyclobutanone for four tertiary amine buffers. A Brønsted β-value of 0.59 was determined from the second-order rate constants determined. Comparison of the results for cyclobutanone to those previously reported for acetone and a 1-phenylacetone derivative, under similar conditions, indicated that the ring strain of the carbocycle appeared to have only a small effect on the general base-catalyzed rate constants for enolization. The similarity of the rate constants for the general base-catalyzed enolization of cyclobutanone to those determined for acetone allowed for an estimation of the limits of the rate constant for protonation of the enolate intermediate of cyclobutanone by the conjugate acid of 3-quinuclidinone (k(BH) = 5 × 10(8) - 2 × 10(9) M(-1) s(-1)). Combining the rate constants for deprotonation of cyclobutanone (k(B)) and protonation of the enolate of cyclobutanone (k(BH)) by 3-quinuclidinone and its conjugate acid, the pK(a) of the α-protons of cyclobutanone has been estimated to be pK(a) = 19.7-20.2.
Determining the pivotal plane of fluid lipid membranes in simulations
NASA Astrophysics Data System (ADS)
Wang, Xin; Deserno, Markus
2015-10-01
Each leaflet of a curved lipid membrane contains a surface at which the area strain vanishes, the so-called pivotal plane. Its distance z0 from the bilayer's midplane arises in numerous contexts, for instance the connection between monolayer and bilayer moduli, stress-profile moments, or area-difference elasticity theories. Here, we propose two precise methods for determining the location of the pivotal plane in computer simulations, both of which rely on monitoring the lipid imbalance across a curved bilayer. The first method considers the ratio of lipid number between the two leaflets of cylindrical or spherical vesicles; it hence requires lipid flip-flop for equilibration. The second method looks at the leaflet difference across local sections cut out from a buckled membrane; this observable equilibrates even in the absence of flip-flop. We apply our methods to two different coarse-grained lipid models, the generic three-bead solvent-free Cooke model and a ten-bead representation of dimyristoylphosphocholine with the explicit solvent MARTINI model. The Cooke model is amenable to both methods and gives results that agree at the percent level. Using it, we also show that the pivotal plane moves outward as lipid curvature becomes more positive. The MARTINI model can only be analyzed with the buckling method; the obtained value z0 = 0.850(11) nm lies about 0.4 nm inwards of the glycerol backbone and is hence unexpectedly small. We attribute this to limitations of the coarse-grained description, suggesting that the location of the pivotal plane might be a good indicator for how well lipid models capture the microscopic origins of curvature elasticity. Finally, we also show that the pivotal plane position itself moves as the membrane is bent. The leading correction is linear in curvature, dependent on the Poisson ratio, and can matter when analyzing experimental results obtained from highly curved inverse hexagonal phases.
The UKIDSS Galactic Plane Survey
NASA Astrophysics Data System (ADS)
Lucas, P. W.; Hoare, M. G.; Longmore, A.; Schröder, A. C.; Davis, C. J.; Adamson, A.; Bandyopadhyay, R. M.; de Grijs, R.; Smith, M.; Gosling, A.; Mitchison, S.; Gáspár, A.; Coe, M.; Tamura, M.; Parker, Q.; Irwin, M.; Hambly, N.; Bryant, J.; Collins, R. S.; Cross, N.; Evans, D. W.; Gonzalez-Solares, E.; Hodgkin, S.; Lewis, J.; Read, M.; Riello, M.; Sutorius, E. T. W.; Lawrence, A.; Drew, J. E.; Dye, S.; Thompson, M. A.
2008-11-01
The UKIDSS Galactic Plane Survey (GPS) is one of the five near-infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying 1868 deg2 of the northern and equatorial Galactic plane at Galactic latitudes -5° < b < 5° in the J, H and K filters and a ~200-deg2 area of the Taurus-Auriga-Perseus molecular cloud complex in these three filters and the 2.12 μm (1-0) H2 filter. It will provide data on ~2 × 109 sources. Here we describe the properties of the data set and provide a user's guide for its exploitation. We also present brief Demonstration Science results from DR2 and from the Science Verification programme. These results illustrate how GPS data will frequently be combined with data taken in other wavebands to produce scientific results. The Demonstration Science comprises six studies. (1) A GPS-Spitzer-GLIMPSE cross-match for the star formation region G28.983-0.603 to identify YSOs. This increases the number of YSOs identified by a factor of 10 compared to GLIMPSE alone. (2) A wide-field study of the M17 nebula, in which an extinction map of the field is presented and the effect of source confusion on luminosity functions in different subregions is noted. (3) H2 emission in the ρ Ophiuchi dark cloud. All the molecular jets are traced back to a single active clump containing only a few protostars, which suggests that the duration of strong jet activity and associated rapid accretion in low-mass protostars is brief. (4) X-ray sources in the nuclear bulge. The GPS data distinguishes local main-sequence counterparts with soft X-ray spectra from nuclear bulge giant counterparts with hard X-ray spectra. (5) External galaxies in the zone of avoidance. The galaxies are clearly distinguished from stars in fields at longitudes l > 90°. (6) IPHAS-GPS optical-infrared spectrophotometric typing. The (i' - J) versus (J - H) diagram is used to distinguish A-F type
NASA Technical Reports Server (NTRS)
Jackson, Wade C.; Portanova, Marc A.
1995-01-01
This paper summarizes three areas of research which were performed to characterize out-of-plane properties of composite materials. In the first investigation, a series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. Failures were significantly different between the 2D materials and the 3D weaves. The 2D materials delaminated between layers due to out-of-plane tensile stresses while the 3D weaves failed due to the formation of radial cracks between the surface plies caused by high circumferential stresses along the inner radius. The strength of the 2D textile composites did not increase relative to the tapes. Final failure in the 3D weaves was caused by a circumferential crack similar to the 2D materials and occurred at a lower bending moment than in other materials. The early failures in the 3D weaves were caused by radial crack formation rather than a low through-the-thickness strength. The second investigation focused on the development of a standard impact test method to measure impact damage resistance. The only impact tests that currently exist are compression after impact (CAI) tests which incorporate elements of both damage resistance and damage tolerance. A new impact test method is under development which uses a quasi-static indentation (QSI) test to directly measure damage resistance. Damage resistance is quantified in terms of the contact force to produce a unit of damage where a metric for damage may be area in C-scan, depth of residual dent , penetration, damage growth, etc. A final draft of an impact standard that uses a QSI test method will be presented to the ASTM Impact Task Group on impact. In the third investigation, the impact damage resistance behavior of a variety of textile materials was studied using the QSI test method. In this study, the force where large damage
Jackson, W.C.; Portanova, M.A.
1995-10-01
This paper summarizes three areas of research which were performed to characterize out-of-plane properties of composite materials. In the first investigation, a series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. Failures were significantly different between the 2D materials and the 3D weaves. The 2D materials delaminated between layers due to out-of-plane tensile stresses while the 3D weaves failed due to the formation of radial cracks between the surface plies caused by high circumferential stresses along the inner radius. The strength of the 2D textile composites did not increase relative to the tapes. Final failure in the 3D weaves was caused by a circumferential crack similar to the 2D materials and occurred at a lower bending moment than in other materials. The early failures in the 3D weaves were caused by radial crack formation rather than a low through-the-thickness strength. The second investigation focused on the development of a standard impact test method to measure impact damage resistance. The only impact tests that currently exist are compression after impact (CAI) tests which incorporate elements of both damage resistance and damage tolerance. A new impact test method is under development which uses a quasi-static indentation (QSI) test to directly measure damage resistance. Damage resistance is quantified in terms of the contact force to produce a unit of damage where a metric for damage may be area in C-scan, depth of residual dent, penetration, damage growth, etc. A final draft of an impact standard that uses a QSI test method will be presented to the ASTM Impact Task Group on impact. In the third investigation, the impact damage resistance behavior of a variety of textile materials was studied using the QSI test method.
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.
On plane submerged laminar jets
NASA Astrophysics Data System (ADS)
Coenen, Wilfried; Sanchez, Antonio L.
2016-11-01
We address the laminar flow generated when a developed stream of liquid of kinematic viscosity ν flowing along channel of width 2 h discharges into an open space bounded by two symmetric plane walls departing from the channel rim with an angle α 1 . Attention is focused on values of the jet volume flux 2 Q such that the associated Reynolds number Re = Qh / ν is of order unity. The formulation requires specification of the boundary conditions far from the channel exit. If the flow is driven by the volume flux, then the far-field solution corresponds to Jeffery-Hamel self-similar flow. However, as noted by Fraenkel (1962), such solutions exist only for α <129o in a limited range of Reynolds numbers 0 <=Re <=Rec (α) (e.g. Rec = 1 . 43 for α = π / 2). It is reasoned that an alternative solution, driven by a fraction of the momentum flux of the feed stream, may also exist for all values of Re and α, including a near-centerline Bickley jet, a surrounding Taylor potential flow driven by the jet entrainment, and a Falkner-Skan near-wall boundary layer. Numerical integrations of the Navier-Stokes equations are used to ascertain the existence of these different solutions.
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.
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.
StrainModeler: A MATHEMATICA™-based program for 3D analysis of finite and progressive strain
NASA Astrophysics Data System (ADS)
Bobillo-Ares, Nilo C.; Aller, Jesús; Bastida, Fernando; Menéndez, Omar; Lisle, Richard J.
2015-05-01
StrainModeler is a program constructed in the MATHEMATICA™ environment that performs 3D progressive strain calculations for lines and planes undergoing any sequence of homogeneous deformations. The main inputs to the system define the initial line or plane to be deformed and the deformation sequence to be applied, including combinations of simple shear, pure shear and volume change. For the deformation of lines, the output of the program is the change of attitude of the initial line, which can be represented by graphics or plotted in an equal-area projection. For the deformation of planes, the program has several outputs: (i) change of attitude of the initial plane; (ii) magnitudes and ratio of the semi-axes of the strain ellipse on the deformed plane; (iii) orientation of the major and minor axes of the strain ellipse on the deformed plane; (iv) orientations of the axial planes of the folds formed on the deformed plane, and (v) area change on the deformed plane. The variation of any of these parameters can be shown against a linear parameter only linked to the number of steps involved in the deformation, as a kind of "time" line, or it can be shown against the variation of a parameter of the strain ellipsoid (e. g.: major axis/minor axis ratio). A sequence of directions can be also visualized as a curve in an equal-area plot. Three applications of the program are presented. In the first, the deformation by simple shear of a plane with any orientation is analyzed. In the second, we explore the formation of recumbent folds in layers with different initial orientations for simple shear and pure shear deformations. In the third, we use StrainModeler to analyze the deformation of a set of folds located in a ductile shear zone in the Variscan Belt of NW Spain.
Rothschild, Freda; Bishop, Alexis I; Kitchen, Marcus J; Paganin, David M
2014-03-24
The Cornu spiral is, in essence, the image resulting from an Argand-plane map associated with monochromatic complex scalar plane waves diffracting from an infinite edge. Argand-plane maps can be useful in the analysis of more general optical fields. We experimentally study particular features of Argand-plane mappings known as "vorticity singularities" that are associated with mapping continuous single-valued complex scalar speckle fields to the Argand plane. Vorticity singularities possess a hierarchy of Argand-plane catastrophes including the fold, cusp and elliptic umbilic. We also confirm their connection to vortices in two-dimensional complex scalar waves. The study of vorticity singularities may also have implications for higher-dimensional fields such as coherence functions and multi-component fields such as vector and spinor fields.
1982-07-01
which makes no use of the hodograph transformation. The advantage of the procedure used here lies in its applicability to the plane strain Mode I problem...solutions of the displacement equation of equilibrium valid on overlapping domains . The final solution is then generated by a consistent matching...y(x)=x+u(x) for all xE%, (1.1)1 is a mappi;: of 9 onto a domain 6* in which u(x) is the displace- ment field. We assume the transformation (1.1) to be
Determination of Dynamic Recrystallization Process by Equivalent Strain
NASA Astrophysics Data System (ADS)
Qin, Xiaomei; Deng, Wei
Based on Tpнoвckiй's displacement field, equivalent strain expression was derived. And according to the dynamic recrystallization (DRX) critical strain, DRX process was determined by equivalent strain. It was found that equivalent strain distribution in deformed specimen is inhomogeneous, and it increases with increasing true strain. Under a certain true strain, equivalent strains at the center, demisemi radius or on tangential plane just below the surface of the specimen are higher than the true strain. Thus, micrographs at those positions can not exactly reflect the true microstructures under the certain true strain. With increasing strain rate, the initial and finish time of DRX decrease. The frozen microstructures of 20Mn23AlV steel with the experimental condition validate the feasibility of predicting DRX process by equivalent strain.
Towards Dualband Megapixel QWIP Focal Plane Arrays
2006-01-01
Journal Article PREPRINT 3. DATES COVERED (From - To) 2006 4. TITLE AND SUBTITLE Towards dualband megapixel QWIP focal plane arrays (PREPRINT) 5a...pixel quantum well infrared photodetector ( QWIP ) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array...registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency
RF/Optical Demonstration: Focal Plane Assembly
NASA Astrophysics Data System (ADS)
Hoppe, D. J.; Chung, S.; Kovalik, J.; Gama, E.; Fernandez, M. M.
2016-11-01
In this article, we describe the second-generation focal plane optical assembly employed in the RF/optical demonstration at DSS-13. This assembly receives reflected light from the two mirror segments mounted on the RF primary. The focal plane assembly contains a fast steering mirror (FSM) to stabilize the focal plane spot, a pupil camera to aid in aligning the two segments, and several additional cameras for receiving the optical signal prior to as well as after the FSM loop.
Realizing in-plane surface diffraction by x-ray multiple-beam diffraction with large incidence angle
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.
Digital scanner infrared focal plane technology
NASA Astrophysics Data System (ADS)
Ortiz, M. A.; Malone, N. R.; Harris, M.; Shin, J.; Byers, S.; Price, D.; Vampola, J.
2011-09-01
Advancements in finer geometry and technology advancements in circuit design now allow placement of digital architecture on cryogenic focal planes while using less power than heritage analog designs. These advances in technology reduce the size, weight, and power of modern focal planes. In addition, the interface to the focal plane is significantly simplified and is more immune to Electromagnetic Interference (EMI). The cost of the customer's instrument after integration with the digital scanning Focal Plane Array (FPA) has been significantly reduced by placing digital architecture such as Analog to digital convertors and Low Voltage Differential Signaling (LVDS) Inputs and Outputs (I/O) on the Read Out Integrated Circuit (ROIC).
Nanostructured carbon films with oriented graphitic planes
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.
Navigating solid medical images by pencils of sectioning planes
NASA Astrophysics Data System (ADS)
Bookstein, Fred L.; Athey, Brian D.; Green, William D. K.; Wetzel, Arthur W.
2000-10-01
Beyond their involvement in ordinary surface rendering, the boundaries of organs in medical images have differential properties that make them quite useful for quantitative understanding. In particular, their geometry affords a framework for navigating the original solid, representing its R3 contents quite flexibility as multiple pseudovolumes R2 x T, where T is ar eal-valued parameter standing for screen time. A navigation is a smoothly parameterized series of image sections characterized by normal direction, centerpoint, scale and orientation. Such filmstrips represent a radical generalization of conventional medical image dynamics. The lances encountered in these navigations can be represented by constructs from classic differential geometry. Sequences of plane sections can be formalized as continuous pencils of planes, sets of cardinality (infinity) 1 that are sometimes explicitly characterized by a real-value parameter and sometimes defined implicitly as the intersection (curve of common elements) of a pair of bundles of (infinity) 2 planes. An example of the first type of navigation is the pencil of planes through the tangent line at one point of a curve; of the second type, the cone of planes through a point tangent to a surface. The further enhancements of centering, orienting, and rescaling in the medical context are intended to leave landmark points or boundary intersections invariant on the screen. Edgewarp, a publicly available software package, allows free play with pencils of planes like these as they section one single enormous medical data resource, the Visible Human data sets from the National Library of Medicine. This paper argues the relative merits of such visualizations over conventional surface-rendered flybys for understanding and communication of associated anatomical knowledge.
Circulation-preserving plane flows of incompressible viscous fluids
NASA Astrophysics Data System (ADS)
Yin, W.-L.
1983-06-01
The present investigation is concerned with a systematic use of the method of complex variables in a study of (generally unsteady) plane solutions of the Navier-Stokes equation. Circulation-preserving flows are considered in the investigation. However, the employed method can also be applied to more general cases. A circulation-preserving plane solution of the Navier-Stokes equation possesses a biharmonic stream function. The stream function may, therefore, be expressed in terms of two complex analytic functions, taking into account Goursat's representation. Attention is given to differential equations in the complex form, the case of steady vorticity, the case of unsteady vorticity with a spatially constant vorticity gradient, solutions with logarithmic vorticity fields, and a proof of completeness.
Scattering of a CW plane wave by a pulse
NASA Astrophysics Data System (ADS)
Trivett, D. H.; Rogers, P. H.
1982-05-01
A procedure similar to the CW crossed-beam calculation of Ingard and Pridmore-Brown (1956) is used to calculate the far field scattered sound pressure of a pulse interacting with a plane wave. The scattered sound is found to be at neither the sum nor the difference frequency. It is suggested that this type of interaction is ideal for investigating the scattering of sound by sound, and a numerical solution is used to discuss the general features of the nearfield waveform.
Euler and Navier-Stokes equations on the hyperbolic plane.
Khesin, Boris; Misiolek, Gerard
2012-11-06
We show that nonuniqueness of the Leray-Hopf solutions of the Navier-Stokes equation on the hyperbolic plane (2) observed by Chan and Czubak is a consequence of the Hodge decomposition. We show that this phenomenon does not occur on (n) whenever n ≥ 3. We also describe the corresponding general Hamiltonian framework of hydrodynamics on complete Riemannian manifolds, which includes the hyperbolic setting.
Euler and Navier–Stokes equations on the hyperbolic plane
Khesin, Boris; Misiołek, Gerard
2012-01-01
We show that nonuniqueness of the Leray–Hopf solutions of the Navier–Stokes equation on the hyperbolic plane ℍ2 observed by Chan and Czubak is a consequence of the Hodge decomposition. We show that this phenomenon does not occur on ℍn whenever n ≥ 3. We also describe the corresponding general Hamiltonian framework of hydrodynamics on complete Riemannian manifolds, which includes the hyperbolic setting. PMID:23091015
The automatic lumber planing mill
Peter Koch
1957-01-01
It is probable that a truly automatic planning operation could be devised if some of the variables commonly present in the mill-run lumber were eliminated and the remaining variables kept under close control. This paper will deal with the more general situation faced by mostl umber manufacturing plants. In other words, it will be assumed that the incoming lumber has...
Autonomous Real-Time Interventional Scan Plane Control With a 3-D Shape-Sensing Needle
Plata, Juan Camilo; Holbrook, Andrew B.; Park, Yong-Lae; Pauly, Kim Butts; Daniel, Bruce L.; Cutkosky, Mark R.
2016-01-01
This study demonstrates real-time scan plane control dependent on three-dimensional needle bending, as measured from magnetic resonance imaging (MRI)-compatible optical strain sensors. A biopsy needle with embedded fiber Bragg grating (FBG) sensors to measure surface strains is used to estimate its full 3-D shape and control the imaging plane of an MR scanner in real-time, based on the needle’s estimated profile. The needle and scanner coordinate frames are registered to each other via miniature radio-frequency (RF) tracking coils, and the scan planes autonomously track the needle as it is deflected, keeping its tip in view. A 3-D needle annotation is superimposed over MR-images presented in a 3-D environment with the scanner’s frame of reference. Scan planes calculated based on the FBG sensors successfully follow the tip of the needle. Experiments using the FBG sensors and RF coils to track the needle shape and location in real-time had an average root mean square error of 4.2 mm when comparing the estimated shape to the needle profile as seen in high resolution MR images. This positional variance is less than the image artifact caused by the needle in high resolution SPGR (spoiled gradient recalled) images. Optical fiber strain sensors can estimate a needle’s profile in real-time and be used for MRI scan plane control to potentially enable faster and more accurate physician response. PMID:24968093
Autonomous real-time interventional scan plane control with a 3-D shape-sensing needle.
Elayaperumal, Santhi; Plata, Juan Camilo; Holbrook, Andrew B; Park, Yong-Lae; Pauly, Kim Butts; Daniel, Bruce L; Cutkosky, Mark R
2014-11-01
This study demonstrates real-time scan plane control dependent on three-dimensional needle bending, as measured from magnetic resonance imaging (MRI)-compatible optical strain sensors. A biopsy needle with embedded fiber Bragg grating (FBG) sensors to measure surface strains is used to estimate its full 3-D shape and control the imaging plane of an MR scanner in real-time, based on the needle's estimated profile. The needle and scanner coordinate frames are registered to each other via miniature radio-frequency (RF) tracking coils, and the scan planes autonomously track the needle as it is deflected, keeping its tip in view. A 3-D needle annotation is superimposed over MR-images presented in a 3-D environment with the scanner's frame of reference. Scan planes calculated based on the FBG sensors successfully follow the tip of the needle. Experiments using the FBG sensors and RF coils to track the needle shape and location in real-time had an average root mean square error of 4.2 mm when comparing the estimated shape to the needle profile as seen in high resolution MR images. This positional variance is less than the image artifact caused by the needle in high resolution SPGR (spoiled gradient recalled) images. Optical fiber strain sensors can estimate a needle's profile in real-time and be used for MRI scan plane control to potentially enable faster and more accurate physician response.
Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane substrate
Chou, Namsun; Lee, Jongho; Kim, Sohee
2014-12-15
This paper describes a reliable fabrication method of stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate. The electrode traces and pads were formed in out-of-plane structures to improve the flexibility and stretchability of the electrode array. The suspended traces and pads were attached to the PDMS substrate via parylene posts that were located nearby the traces and under the pads. As only conventional micro-electro-mechanical systems techniques were used, the out-of-plane electrode arrays were clearly fabricated at wafer level with high yield and reliability. Also, bi-layer out-of-plane electrodes were formed through additional fabrication steps in addition to mono-layer out-of-plane electrodes. The mechanical characteristics such as the stretchability, flexibility, and foldability of the fabricated electrodes were evaluated, resulting in stable electrical connection of the metal traces with up to 32.4% strain and up to 360° twist angle over 25 mm. The durability in stretched condition was validated by cyclic stretch test with 10% and 20% strain, resulting in electrical disconnection at 8600 cycles when subjected to 20% strain. From these results, it is concluded that the proposed fabrication method produced highly reliable, out-of-plane and stretchable electrodes, which would be used in various flexible and stretchable electronics applications.
NASA Astrophysics Data System (ADS)
Stoudt, M. R.; Hubbard, J. B.; Iadicola, M. A.; Banovic, S. W.
2009-07-01
Three-dimensional, matrix-based statistical analysis methods were developed and integrated with high-resolution topographical imaging, to assess how microstructural changes influence the evolution of plastic deformation and strain localization in a commercial AA5754-O aluminum sheet in three in-plane strain modes. Analysis of the raw surface data revealed that the general composition of the surface roughness was highly sensitive to strain mode and strain level. The microstructural conditions that promote strain localization were assessed by extending a profile-based surface roughness parameter ( Rt) to matrix form. Both analyses revealed that different strain modes produce characteristic dissimilarities in the deformation at the grain level. The localization data can be well characterized with a two-parameter Weibull distribution, suggesting that strain localization is a stochastic process that can be modeled reliably with Weibull statistics. This study clearly demonstrates that an accurate and straightforward probabilistic expression that captures the microstructural subtleties produced by plastic deformation can be developed from rigorous analyses of raw topographic data. Because variations in surface morphology profoundly influence the reliability of the numerical models used to predict strain localization, incorporating expressions of this type could greatly enhance the accuracy of these models.
Hybrid inflation in the complex plane
NASA Astrophysics Data System (ADS)
Buchmüller, W.; Domcke, V.; Kamada, K.; Schmitz, K.
2014-07-01
Supersymmetric hybrid inflation is an exquisite framework to connect inflationary cosmology to particle physics at the scale of grand unification. Ending in a phase transition associated with spontaneous symmetry breaking, it can naturally explain the generation of entropy, matter and dark matter. Coupling F-term hybrid inflation to soft supersymmetry breaking distorts the rotational invariance in the complex inflaton plane — an important fact, which has been neglected in all previous studies. Based on the δ N formalism, we analyze the cosmological perturbations for the first time in the full two-field model, also taking into account the fast-roll dynamics at and after the end of inflation. As a consequence of the two-field nature of hybrid inflation, the predictions for the primordial fluctuations depend not only on the parameters of the Lagrangian, but are eventually fixed by the choice of the inflationary trajectory. Recognizing hybrid inflation as a two-field model resolves two shortcomings often times attributed to it: the fine-tuning problem of the initial conditions is greatly relaxed and a spectral index in accordance with the PLANCK data can be achieved in a large part of the parameter space without the aid of supergravity corrections. Our analysis can be easily generalized to other (including large-field) scenarios of inflation in which soft supersymmetry breaking transforms an initially single-field model into a multi-field model.
Solar Impulse's Solar-Powered Plane
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.
Solar Impulse's Solar-Powered Plane
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.
Robust algorithms for anatomic plane primitive detection in MR
NASA Astrophysics Data System (ADS)
Dewan, Maneesh; Zhan, Yiqiang; Peng, Zhigang; Zhou, Xiang Sean
2009-02-01
One of primary challenges in the medical image data analysis is the ability to handle abnormal, irregular and/or partial cases. In this paper, we present two different robust algorithms towards the goal of automatic planar primitive detection in 3D volumes. The overall algorithm is a bottoms-up approach starting with the anatomic point primitives (or landmarks) detection. The robustness in computing the planar primitives is built in through both a novel consensus-based voting approach, and a random sampling-based weighted least squares regression method. Both these approaches remove inconsistent landmarks and outliers detected in the landmark detection step. Unlike earlier approaches focused towards a particular plane, the presented approach is generic and can be easily adapted to computing more complex primitives such as ROIs or surfaces. To demonstrate the robustness and accuracy of our approach, we present extensive results for automatic plane detection (Mig-Sagittal and Optical Triangle planes) in brain MR-images. In comparison to ground truth, our approach has marginal errors on about 90 patients. The algorithm also works really well under adverse conditions of arbitrary rotation and cropping of the 3D volume. In order to exhibit generalization of the approach, we also present preliminary results on intervertebrae-plane detection for 3D spine MR application.
Quantum-Well Infrared Photodetector (QWIP) Focal Plane Assembly
NASA Technical Reports Server (NTRS)
Jhabvala, Murzy; Jhabvala, Christine A.; Ewin, Audrey J.; Hess, Larry A.; Hartmann, Thomas M.; La, Anh T.
2012-01-01
A paper describes the Thermal Infrared Sensor (TIRS), a QWIP-based instrument intended to supplement the Operational Land Imager (OLI) for the Landsat Data Continuity Mission (LDCM). The TIRS instrument is a far-infrared imager operating in the pushbroom mode with two IR channels: 10.8 and 12 microns. The focal plane will contain three 640x512 QWIP arrays mounted on a silicon substrate. The silicon substrate is a custom-fabricated carrier board with a single layer of aluminum interconnects. The general fabrication process starts with a 4-in. (approx.10-cm) diameter silicon wafer. The wafer is oxidized, a single substrate contact is etched, and aluminum is deposited, patterned, and alloyed. This technology development is aimed at incorporating three large-format infrared detecting arrays based on GaAs QWIP technology onto a common focal plane with precision alignment of all three arrays. This focal plane must survive the rigors of flight qualification and operate at a temperature of 43 K (-230 C) for five years while orbiting the Earth. The challenges presented include ensuring thermal compatibility among all the components, designing and building a compact, somewhat modular system and ensuring alignment to very tight levels. The multi-array focal plane integrated onto a single silicon substrate is a new application of both QWIP array development and silicon wafer scale integration. The Invar-based assembly has been tested to ensure thermal reliability.
Study the Z-Plane Strip Capacitance
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.
Influence of strain on the conduction band structure of strained silicon nanomembranes.
Euaruksakul, C; Li, Z W; Zheng, F; Himpsel, F J; Ritz, C S; Tanto, B; Savage, D E; Liu, X S; Lagally, M G
2008-10-03
The influence of in-plane biaxial strain on the conduction bands of Si is explored using elastically strained Si(001) nanomembranes and high-resolution x-ray absorption measurements with electron yield detection. The strain-induced splitting of the conduction band minimum and the energy shifts of two higher conduction bands near L1 and L3 are clearly resolved. The linear increase of the splitting of the conduction band minimum with increasing strain and the nonlinear shift of the L1 point toward the conduction band minimum agree quantitatively with current theories.
Simple Numerical Simulation of Strain Measurement
NASA Technical Reports Server (NTRS)
Tai, H.
2002-01-01
By adopting the basic principle of the reflection (and transmission) of a plane polarized electromagnetic wave incident normal to a stack of films of alternating refractive index, a simple numerical code was written to simulate the maximum reflectivity (transmittivity) of a fiber optic Bragg grating corresponding to various non-uniform strain conditions including photo-elastic effect in certain cases.
NASA Astrophysics Data System (ADS)
Heilbronner, Renée
2017-04-01
2017 marks the 50th anniversary of the publication of John Ramsay's well known textbook "Folding and Fracturing of Rocks" - ... and the 30th anniversary of the rejection of a rather less well known paper entitled "Strain: Fact or Fiction?" submitted by Renée Panozzo to the Journal of Structural Geology. The gist of the paper was simple and straight forward: it was argued that not every fabric that can be observed in deformed rocks is necessarily a measure of the amount of strain the rock incurred. A distinction was made between a general "fabric", i.e., the traceable geometry of grain boundaries, for example, and a so-called "strain fabric", i.e., the model geometry that would result from homogeneously straining an initially isotropic fabric and that would exhibit at least orthorhombic symmetry. To verify if a given fabric was indeed a strain fabric it was therefore suggested to use the SURFOR method (published by Panozzo) and to carry out a so-called strain test, i.e., a check of symmetry, before interpreting the results of a fabric analysis in terms of strain. The problem with the paper was that it was very obviously written out of frustration. The frustration came form having reviewed a number of manuscripts which tried to use the then novel SURFOR method for strain analysis without first checking if the the fabric was a indeed a "strain fabric" or not, and then blaming the SURFOR method for producing ambiguous results. As a result, the paper was not exactly well balanced and carefully thought out. It was considered "interesting but not scholarly" by one of the reviewers and down-right offensive by the second. To tell the truth, however, the paper was not formally rejected. The editor Sue Treagus strongly encouraged Panozzo to revise the paper, ... and 30 years later, I will follow her advise and offer a revised paper as a tribute to John Ramsay. To quote from the original manuscript: "We should be a little more impressed that strain works so well, and less
Skov, Søren Nielsen; Røpcke, Diana Mathilde; Ilkjær, Christine; Rasmussen, Jonas; Tjørnild, Marcell Juan; Jimenez, Jorge H; Yoganathan, Ajit P; Nygaard, Hans; Nielsen, Sten Lyager; Jensen, Morten Olgaard
2016-03-21
Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements. Each arm was mounted with strain gauges on four circumferential elements to measure out-of-plane forces, and the central parts of the X-arms were mounted with two strain gauges to measure in-plane forces. A dedicated calibration setup was developed to calibrate isolated forces with tension and compression for in- and out-of-plane measurements. With this setup, it was possible with linear equations to isolate and distinguish measured forces between the two planes and minimize transducer arm crosstalk. An in-vitro test was performed to verify the crosstalk elimination method and the assumptions behind it. The force transducer was implanted and evaluated in an 80kg porcine in-vivo model. Following crosstalk elimination, in-plane systolic force accumulation was found to be in average 4.0±0.1N and the out-of-plane annular segments experienced an average force of 1.4±0.4N. Directions of the systolic out-of-plane forces indicated movements towards a saddle shaped annulus, and the transducer was able to measure independent directional forces in individual annular segments. Further measurements with the new transducer coupled with clinical annuloplasty rings will provide a detailed insight into the biomechanical dynamics of these devices.
Lower incisor inclination regarding different reference planes.
Zataráin, Brenda; Avila, Josué; Moyaho, Angeles; Carrasco, Rosendo; Velasco, Carmen
2016-09-01
The purpose of this study was to assess the degree of lower incisor inclination with respect to different reference planes. It was an observational, analytical, longitudinal, prospective study conducted on 100 lateral cephalograms which were corrected according to the photograph in natural head position in order to draw the true vertical plane (TVP). The incisor mandibular plane angle (IMPA) was compensated to eliminate the variation of the mandibular plane growth type with the formula "FMApx.- 25 (FMA) + IMPApx. = compensated IMPA (IMPACOM)". As the data followed normal distribution determined by the KolmogorovSmirnov test, parametric tests were used for the statistical analysis, Ttest, ANOVA and Pearson coefficient correlation test. Statistical analysis was performed using a statistical significance of p <0.05. There is correlation between TVP and NB line (NB) (0.8614), Frankfort mandibular incisor angle (FMIA) (0.8894), IMPA (0.6351), Apo line (Apo) (0.609), IMPACOM (0.8895) and McHorris angle (MH) (0.7769). ANOVA showed statistically significant differences between the means for the 7 variables with 95% confidence level, P=0.0001. The multiple range test showed no significant difference among means: APoNB (0.88), IMPAMH (0.36), IMPANB (0.65), FMIAIMPACOM (0.01), FMIATVP (0.18), TVPIMPACOM (0.17). There was correlation among all reference planes. There were statistically significant differences among the means of the planes measured, except for IMPACOM, FMIA and TVP. The IMPA differed significantly from the IMPACOM. The compensated IMPA and the FMIA did not differ significantly from the TVP. The true horizontal plane was mismatched with Frankfort plane in 84% of the sample with a range of 19°. The true vertical plane is adequate for measuring lower incisor inclination.
Mosaic focal plane for star sensors
NASA Astrophysics Data System (ADS)
Chang, N. C.
1981-02-01
The basic principles of star sensors are reviewed with reference to the advantages of replacing photodiodes, image dissectors, and vidicons with mosaic charge transfer device (CTD) focal planes. The desirable characteristics of CTD focal planes include: high uniformity, high transfer effect, low dark current, low hot and cold spots, low dead space, low angular misalignment, high coplanarity, and high thermal stability. An implementation of a mosaic CTD array star sensor which achieves high angular position accuracy and frequency attitude update is presented. Two focal plane packaging concepts, the planar and vertical board packagings, are examined.
NASA Astrophysics Data System (ADS)
Dixit, Ripudaman; Tyagi, Prashant; Kushvaha, Sunil Singh; Chockalingam, Sreekumar; Yadav, Brajesh Singh; Sharma, Nita Dilawar; Kumar, M. Senthil
2017-04-01
We have investigated the influence of growth temperature on the in-plane strain, structural, optical and mechanical properties of heteroepitaxially grown GaN layers on sapphire (0001) substrate by laser molecular beam epitaxy (LMBE) technique in the temperature range 500-700 °C. The GaN epitaxial layers are found to have a large in-plane compressive stress of about 1 GPa for low growth temperatures but the strain drastically reduced in the layer grown at 700 °C. The nature of the in-plane strain has been analyzed using high resolution x-ray diffraction, atomic force microscopy (AFM), Raman spectroscopy and photoluminescence (PL) measurements. From AFM, a change in GaN growth mode from grain to island is observed at the high growth temperature above 600 °C. A blue shift of 20-30 meV in near band edge PL emission line has been noticed for the GaN layers containing the large in-plane strain. These observations indicate that the in-plane strain in the GaN layers is dominated by a biaxial strain. Using nanoindentation, it is found that the indentation hardness and Young's modulus of the GaN layers increases with increasing growth temperature. The results disclose the critical role of growth mode in determining the in-plane strain and mechanical properties of the GaN layers grown by LMBE technique.
Strain-Induced Energy Band Gap Opening in Two-Dimensional Bilayered Silicon Film
NASA Astrophysics Data System (ADS)
Ji, Z.; Zhou, R.; Lew Yan Voon, L. C.; Zhuang, Y.
2016-10-01
This work presents a theoretical study of the structural and electronic properties of bilayered silicon film (BiSF) under in-plane biaxial strain/stress using density functional theory (DFT). Atomic structures of the two-dimensional (2-D) silicon films are optimized by using both the local-density approximation (LDA) and generalized gradient approximation (GGA). In the absence of strain/stress, five buckled hexagonal honeycomb structures of the BiSF with triangular lattice have been obtained as local energy minima, and their structural stability has been verified. These structures present a Dirac-cone shaped energy band diagram with zero energy band gaps. Applying a tensile biaxial strain leads to a reduction of the buckling height. Atomically flat structures with zero buckling height have been observed when the AA-stacking structures are under a critical biaxial strain. Increase of the strain between 10.7% and 15.4% results in a band-gap opening with a maximum energy band gap opening of ˜0.17 eV, obtained when a 14.3% strain is applied. Energy band diagrams, electron transmission efficiency, and the charge transport property are calculated. Additionally, an asymmetric energetically favorable atomic structure of BiSF shows a non-zero band gap in the absence of strain/stress and a maximum band gap of 0.15 eV as a -1.71% compressive strain is applied. Both tensile and compressive strain/stress can lead to a band gap opening in the asymmetric structure.
Resolution in 3D in multifocal plane microscopy
NASA Astrophysics Data System (ADS)
Chao, Jerry; Ram, Sripad; Abraham, Anish V.; Ward, E. Sally; Ober, Raimund J.
2008-02-01
Using single molecule microscopy, biological interactions can be imaged and studied at the level of individual biomolecules. When characterizing an imaged biological interaction, the distance separating the two participating biomolecules can provide valuable information. Therefore, the resolvability of an imaging setup is of practical significance in the analysis of the acquired image data. Importantly, the resolvability of the imaging setup needs evaluation in the 3D context, since in general biomolecules reside in 3D space within the cellular environment. We recently introduced an information-theoretic 2D resolution measure which shows that the resolution limit due to Rayleigh's criterion can be overcome. This new result predicts that the resolution of optical microscopes is not limited, but rather can be improved with increased photon counts detected from the single molecules. The 2D result was subsequently extended to the 3D context, and the proposed information-theoretic 3D resolution measure can readily be used to determine the resolvability of a conventional single focal plane imaging setup. Here, we consider the 3D resolution measure for a multifocal plane microscope setup, an imaging system which allows the concurrent imaging of multiple focal planes within a specimen. The technique is useful in applications such as the tracking of subcellular objects in 3D. By comparing their 3D resolution measures, we find a two-plane setup to outperform a comparable conventional single-plane setup in resolvability over a range of axial locations for the single molecule pair. Moreover, we investigate and compare the impact of noise on the resolvability of the two setups.
Strain Gage Signal Interpretation.
1986-02-01
blades and vanes in many engines have been collected, played back and examined. The engine types encompass GE’s stable of turbine engines from the small...aeromechanical engineer . 1.3 SUMMARY OF RESULTS Strain gage signals from vibrating rotor blades and vanes were collected, examined, classified, and generalized...turboprops, to turbojets and to the large high bypass turbofan engines . Test conditions include all the phases that are investigated
High temperature capacitive strain gage
NASA Astrophysics Data System (ADS)
Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.
1990-01-01
Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.
High Temperature Capacitive Strain Gage
NASA Technical Reports Server (NTRS)
Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.
1990-01-01
Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.
A scalable control plane for optical-packet-switched networks
NASA Astrophysics Data System (ADS)
Kang, J.; Reed, M. J.
2005-02-01
This paper describes the design considerations and architecture of a Generalized Multi-Protocol Label Switching (GMPLS)-based scalable control plane that we are prototyping for optical packet switched (OPS) networks. Functional components of the control plane include a user network interface (UNI), optical label coding, multi-layer routing/traffic engineering algorithm and integrated signaling protocol. Initial implementation and experimentation has demonstrated the feasibility of our prototype as a testbed for various control schemes for OPS networks. One key element of the architecture proposed is the use of external MPLS labeling controlled by the UNI. This proposal reduces the load on the OPS domain header processing while having little impact on the MPLS domain.
Wei, Q.; Dalvit, D. A. R.; Lombardo, F. C.; Mazzitelli, F. D.; Onofrio, R.
2010-05-15
We report on measurements performed on an apparatus aimed to study the Casimir force in the cylinder-plane configuration. The electrostatic calibrations evidence anomalous behaviors in the dependence of the electrostatic force and the minimizing potential upon distance. We discuss analogies and differences of these anomalies with respect to those already observed in the sphere-plane configuration. At the smallest explored distances we observe frequency shifts of non-Coulombian nature preventing the measurement of the Casimir force in the same range. We also report on measurements performed in the parallel-plane configuration, showing that the dependence on distance of the minimizing potential, if present at all, is milder than in the sphere-plane or cylinder-plane geometries. General considerations on the interplay between the distance-dependent minimizing potential and the precision of Casimir force measurements in the range relevant to detect the thermal corrections for all geometries are finally reported.
Strain engineered barium strontium titanate for tunable thin film resonators
Khassaf, H.; Khakpash, N.; Sun, F.; Sbrockey, N. M.; Tompa, G. S.; Kalkur, T. S.; Alpay, S. P.
2014-05-19
Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.
Hydrodynamic stability of compressible plane Couette flow
Chagelishvili, G.D. Department of Plasma Physics, Space Research Institute, str. Profsoyuznaya 84 Rogava, A.D. ); Segal, I.N. Department of Plasma Physics, Space Research Institute, str. Profsoyuznaya 84/32, 117810 Moscow )
1994-12-01
The evolution of two-dimensional spatial Fourier harmonics in a compressible plane Couette flow is considered. A new mechanism of energy exchange between the mean flow and sound-type perturbations is discovered.
Geometric and analytic problems on bicomplex plane
NASA Astrophysics Data System (ADS)
Dimiev, Stancho; Stoev, Peter; Stoilova, Stanislava
2015-11-01
Let us recall that the bicomplex plane is a complex ring of complex dimension 2. It consists of couples of the kind (z, w) = z + jw, where z and w are complex numbers and j is a symbol with the property j2 = -1. We note that the bicomplex plane admits singular points. The set of these singular points coincides with the cross-choped set of complex bisectrices (z, ±z), z is a complex. The main problem in the function theory on the bicomplex plane is to describe the interconnection between the same theory of the cross-choped subset and whole bicomplex plane. The first theory is of one complex variable and the second one is of two complex variables. Another problems are related with the comformal mappings and the movement of a partials of this subset on the whole one. Presented paper is a start studies in this direction.
Reconnaissance with slant plane circular SAR imaging.
Soumekh, M
1996-01-01
This paper presents a method for imaging from the slant plane data collected by a synthetic aperture radar (SAR) over the full rotation or a partial segment of a circular flight path. A Fourier analysis for the Green's function of the imaging system is provided. This analysis is the basis of an inversion for slant plane circular SAR data. The reconstruction algorithm and resolution for this SAR system are outlined. It is shown that the slant plane circular SAR, unlike the slant plane linear SAR, has the capability to extract three-dimensional imaging information of a target scene. The merits of the algorithm are demonstrated via a simulated target whose ultra wideband foliage penetrating (FOPEN) or ground penetrating (GPEN) ultrahigh frequency (UHF) radar signature varies with the radar's aspect angle.
Single plane angiography: Current applications and limitations
NASA Technical Reports Server (NTRS)
Falsetti, H. L.; Carroll, R. J.
1975-01-01
Technical errors in measurement of one plane cineangiography are identified. Examples of angiographic estimates of left ventricular geometry are given. These estimates of contractility are useful in evaluating myocardial performance.
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.
NASA Technical Reports Server (NTRS)
Gates, Thomas S.
1992-01-01
In order to understand matrix dominated behavior in laminated polymer matrix composites, an elastic/viscoplastic constitutive model was developed and used to predict stress strain behavior of off-axis and angle-ply symmetric laminates under in-plane, tensile axial loading. The model was validated for short duration tests at elevated temperatures. Short term stress relaxation and short term creep, strain rate sensitivity, and material nonlinearity were accounted for. The testing times were extended for longer durations, and periods of creep and stress relaxation were used to investigate the ability of the model to account for long term behavior. The model generally underestimated the total change in strain and stress for both long term creep and long term relaxation respectively.
Differentialless geometry of plane curves
NASA Astrophysics Data System (ADS)
Latecki, Longin J.; Rosenfeld, Azriel
1997-10-01
We introduce a class of planar arcs and curves, called tame arcs, which is general enough to describe the boundaries of planar real objects. A tame arc can have smooth parts as well as sharp corners; thus a polygonal arc is tame. On the other hand, this class of arcs is restrictive enough to rule out pathological arcs which have infinitely many inflections or which turn infinitely often: a tame arc can have only finitely many inflections, and its total absolute turn must be finite. In order to relate boundary properties of discrete objects obtained by segmenting digital images to the corresponding properties of their continuous originals, the theory of tame arcs is based on concepts that can be directly transferred from the continuous to the discrete domain. A tame arc is composed of a finite number of supported arcs. We define supported digital arcs and motivate their definition by the fact that hey can be obtained by digitizing continuous supported arcs. Every digital arc is tame, since it contains a finite number of points, and therefore it can be decomposed into a finite number of supported digital arcs.
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.
Machine Learning for the Knowledge Plane
2006-06-01
methods rely on careful engineering of the representation, the choice of algorithm, and so forth. The knowledge plane requires a more autonomous...learning capability that can operate in real time without continuous knowledge engineering . 2. Learning online. Most existing learning methods learn...detection and fault diagnosis. The central task of the knowledge plane is to detect anomalies and faults. Machine learning methods can be applied to learn
Trajectories of balls on the inclined plane
NASA Astrophysics Data System (ADS)
Schröer, H.
We view trajectories of projection on the inclined plane. We will see that the inclined throw in the homogeneous field is a special case of the throw on the inclined plane. Here the trajectories of projection are dependent upon throwing angle and initial velocity. First we will treat the frictionless case. Thereafter, it will be easier to understand the friction case. In chapter 2 we take into consideration friction. There is an english and a german edition.
Carroll symmetry of plane gravitational waves
NASA Astrophysics Data System (ADS)
Duval, C.; Gibbons, G. W.; Horvathy, P. A.; Zhang, P.-M.
2017-09-01
The well-known 5-parameter isometry group of plane gravitational waves in 4 dimensions is identified as Lévy-Leblond’s Carroll group in 2+1 dimensions with no rotations. Our clue is that plane waves are Bargmann spaces into which Carroll manifolds can be embedded. We also comment on the scattering of light by a gravitational wave and calculate its electric permittivity considered as an impedance-matched metamaterial.
Strain-phonon coupling in (111)-oriented perovskite oxides
NASA Astrophysics Data System (ADS)
Moreau, Magnus; Marthinsen, Astrid; Selbach, Sverre M.; Tybell, Thomas
2017-09-01
Strain-phonon coupling, in terms of the shift in phonon frequencies under biaxial strain, is studied by density functional theory calculations for 20 perovskite oxides strained in their (111) and (001) planes. While the strain-phonon coupling under (001) strain follows the established, intuitive trends, the response to (111) strain is more complex. Here we show that strain-phonon coupling under (111) strain can be rationalized in terms of the Goldschmidt tolerance factor and the formal cation oxidation states. The established trends for coupling between (111) strain and in-phase and out-of-phase octahedral rotational modes as well as polar modes provide guidelines for rational design of (111)-oriented perovskite thin films.
In-plane Anisotropy of Cobalt Nanoparticles
NASA Astrophysics Data System (ADS)
Leslie-Pelecky, Diandra L.; Gibson, Charles P.
1996-03-01
Hexagonal cobalt platelets of diameter 150 nm and thickness 15 nm have been fabricated using ultrasonic-assisted chemical reduction.(Charles P. Gibson and Kathy J. Putzer, Science 267, 1338 (1995)) Lorenz microscopy indicated that the magnetic moment of these particles lies in the basal plane of the platelets (unlike bulk cobalt in which the moment is preferentially oriented perpendicular to the basal plane). Disks with approximately 75to the plane of the disk have been measured and confirm a strong in-plane anisotropy with saturation magnetization of 150 emu/g (compared with the bulk value of 163 emu/g). The anisotropy field is approximately 2.5 T at room temperature. Temperature-dependent magnetization shows irreversibility between field cooled and zero-field-cooled configurations. A large, broad cusp at 150 K and a smaller cusp at 12 K are observed in both field-parallel-to-the-plane and field-perpendicular-to-the-plane configurations. The 12 K feature is also seen in assemblies of randomly oriented particles and is attributed to random anisotropy; however, the cusp at 150 K is only seen in the oriented samples.
Cell division plane orientation based on tensile stress in Arabidopsis thaliana
Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier
2016-01-01
Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson–Dumais rule generalizes Errera’s rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson–Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson–Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants. PMID:27436908
Enhanced in-plane mechanical properties of nanoporous graphene-carbon nanotube network
NASA Astrophysics Data System (ADS)
Qin, Huasong; Sun, Yu; Liu, Jefferson Zhe; Liu, Yilun
2017-06-01
Three dimensional graphene-carbon nanotube networks (3D-GC) have attracted great interests due to their superior thermal, optical, and hydrogen storage properties. In our work, the in-plane mechanical properties of nanoporous 3D-GC with different diameters of the joint carbon nanotube (CNT) and porosity have been studied. During in-plane tension, the fracture of 3D-GC first initiates at the heptagonal defects of the junctions between graphene sheets and CNTs where large tensile residual stress is observed. The in-plane tensile strength of 3D-GC decreases with the increasing of CNT parameter and porosity, and the tensile modulus is mainly determined by the porosity. Although the fracture strain decreases with the CNT diameter, it increases with the porosity. Compared to the nanoporous graphene, 3D-GC has larger in-plane tensile strength and fracture strain due to the additional support of CNTs. However, the in-plane tensile modulus of 3D-GC is usually smaller than that of the nanoporous graphene due to the wrinkled configuration of 3D-GC. By considering the stress concentration and additional support of CNTs, a theoretical model is proposed which can describe the molecular dynamics simulation results well.
Wangorsch, A; Larsson, H; Messmer, M; García-Moral, A; Lauer, I; Wolfheimer, S; Schülke, S; Bartra, J; Vieths, S; Lidholm, J; Scheurer, S
2016-05-01
Non-specific lipid transfer proteins (nsLTP) are considered to provoke allergic symptoms to plane tree pollen, which are frequently associated with peach allergy. The objective was to clone the cDNA of plane pollen nsLTP Pla a 3, to characterize IgE-binding and allergenic potency of recombinant Pla a 3 in comparison to its natural counterpart and peach nsLTP Pru p 3. Natural Pla a 3 was purified from plane pollen and analysed by mass spectrometry (MS). Recombinant Pla a 3 was characterized by SDS-PAGE and CD spectroscopy. Specific IgE to extract, components of plane pollen and Pru p 3 was measured by ImmunoCAP in sera of patients allergic to either plane pollen (n = 10), peach (n = 15) or both (n = 15). Biological potency of the proteins was investigated by in vitro mediator release assays and IgE cross-reactivity by competitive ELISA. Two Pla a 3 isoforms were identified. Recombinant Pla a 3 showed high purity, structural integrity, IgE-binding capacity comparable to nPla a 3 and biological potency. Sensitization to plane pollen extract was confirmed in 24/25 plane pollen allergics. The frequency of sensitization to Pla a 3 was 53% among patients allergic to both plane pollen and peach and 10% among plane pollen allergics tolerating peach where most patients were sensitized to Pla a 1. Pla a 3 and Pru p 3 showed strong bi-directional IgE cross-reactivity in patients allergic to peach and plane pollen, but not in peach allergics tolerating plane pollen. Levels of IgE-binding were generally higher to Pru p 3 than to Pla a 3. Sensitization to Pla a 3 is relevant in a subgroup of plane pollen allergics with concomitant peach allergy. IgE testing with Pla a 3 may serve as a marker to identify plane pollen allergic patients at risk of LTP-mediated food reactions and thereby improve in vitro diagnostic procedures. © 2016 John Wiley & Sons Ltd.
Inhomogeneous strain-induced half-metallicity in bent zigzag graphene nanoribbons
NASA Astrophysics Data System (ADS)
Zhang, Dong-Bo; Wei, Su-Huai
2017-08-01
Realization of half-metallicity in low dimensional materials is a fundamental challenge for nano spintronics, which is a critical component for next-generation information technology. Using the method of generalized Bloch theorem, we show that an in-plane bending can induce inhomogeneous strains, which in turn lead to spin-splitting in zigzag graphene nanoribbons and results in the highly desired half-metallic state. Unlike the previously proposed scheme that requires unrealistically strong external electric fields, the obtained half-metallicity with sizeable half-metallic gap and high energetic stability of magnetic order of edge states requires only relatively low-level strain in the in-plane bending. Given the superior structural flexibility of graphene and the recent experimental advances in controllable synthesis of graphene nanoribbons, our design provides a hitherto most practical approach to the realization of half-metallicity in low dimensional systems. This work, thus paves a way towards the design of nanoscale spintronic devices through strain engineering.
Strain effects on oxygen vacancy energetics in KTaO3
Xi, Jianqi; Xu, Haixuan; Zhang, Yanwen; ...
2017-02-07
Due to lattice mismatch between epitaxial films and substrates, in-plane strain fields are produced in the thin films, with accompanying structural distortions, and ion implantation can be used to controllably engineer the strain throughout the film. Because of the strain profile, local defect energetics are changed. In this study, the effects of in-plane strain fields on the formation and migration of oxygen vacancies in KTaO3 are investigated using first-principles calculations. In particular, the doubly positive charged oxygen vacancy (V2+O) is studied, which is considered to be the main charge state of the oxygen vacancy in KTaO3. We find that themore » formation energies for oxygen vacancies are sensitive to in-plane strain and oxygen position. The local atomic configuration is identified, and strong relaxation of local defect structure is mainly responsible for the formation characteristics of these oxygen vacancies. Based on the computational results, formation-dependent site preferences for oxygen vacancies are expected to occur under epitaxial strain, which can result in orders of magnitude differences in equilibrium vacancy concentrations on different oxygen sites. In addition, all possible migration pathways, including intra- and inter-plane diffusions, are considered. In contrast to the strain-enhanced intra-plane diffusion, the diffusion in the direction normal to the strained plane is impeded under the epitaxial strain field. Lastly, these anisotropic diffusion processes can further enhance site preferences.« less
Evidence for residual elastic strain in deformed natural quartz
Kunz, Martin; Chen, Kai; Tamura,Nobumichi; Wenk, Hans-Rudolf
2009-01-30
Residual elastic strain in naturally deformed, quartz-containing rocks can be measured quantitatively in a petrographic thin section with high spatial resolution using Laue microdiffraction with white synchrotron x-rays. The measurements with a resolution of one micrometer allow the quantitative determination of the deviatoric strain tensor as a function of position within the crystal investigated. The observed equivalent strain values of 800-1200 microstrains represent a lower bound of the actual preserved residual strain in the rock, since the stress component perpendicular to the cut sample surface plane is released. The measured equivalent strain translates into an equivalent stress in the order of {approx} 50 MPa.
Strain modification on electronic transport of the phosphorene nanoribbon
NASA Astrophysics Data System (ADS)
Yuan, Yawen; Cheng, Fang
2017-07-01
We demonstrate theoretically how local strains can be tailored to control quantum transport of carriers on monolayer armchair and zigzag phosphorene nanoribbon. We find that the electron tunneling is forbidden when the in-plane strain exceeds a critical value. The critical strain is different for different crystal orientation of the ribbons, widths, and incident energies. By tuning the Fermi energy and strain, the channels can be transited from opaque to transparent. Moreover, for the zigzag-phosphorene nanoribbon, the two-fold degenerate quasi-flat edge band splits completely under certain strain. These properties provide us an efficient way to control the transport of monolayer phosphorene-based microstructure.
... flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare
On the stability of satellite planes - I. Effects of mass, velocity, halo shape and alignment
NASA Astrophysics Data System (ADS)
Fernando, Nuwanthika; Arias, Veronica; Guglielmo, Magda; Lewis, Geraint F.; Ibata, Rodrigo A.; Power, Chris
2017-02-01
The recently discovered vast thin plane of dwarf satellites orbiting the Andromeda Galaxy (M31) adds to the mystery of the small-scale distribution of the Local Group's galaxy population. Such well-defined planar structures are apparently rare occurrences in cold dark matter cosmological simulations, and we lack a coherent explanation of their formation and existence. In this paper, we explore the long-term survivability of thin planes of dwarfs in galactic haloes, focusing, in particular, on systems mimicking the observed Andromeda distribution. The key results show that, in general, planes of dwarf galaxies are fragile, sensitive to the shape of the dark matter halo and other perturbing effects. In fact, long-lived planes of satellites only exist in polar orbits in spherical dark matter haloes, presenting a challenge to the observed Andromeda plane that is significantly tilted with respect to the optical disc. Our conclusion is that, in the standard cosmological models, planes of satellites are generally short lived, and hence we must be located at a relatively special time in the evolution of the Andromeda Plane, lucky enough to see its coherent pattern.
Kaczmarczyk, Andreas; Campagne, Sébastien; Danza, Francesco; Metzger, Lisa C.; Vorholt, Julia A.; Francez-Charlot, Anne
2011-01-01
The general stress response in Alphaproteobacteria was recently described to depend on the alternative sigma factor σEcfG, whose activity is regulated by its anti-sigma factor NepR. The response regulator PhyR, in turn, regulates NepR activity in a partner-switching mechanism according to which phosphorylation of PhyR triggers sequestration of NepR by the sigma factor-like effector domain of PhyR. Although genes encoding predicted histidine kinases can often be found associated with phyR, little is known about their role in modulation of PhyR phosphorylation status. We demonstrate here that the PhyR-NepR-σEcfG cascade is important for multiple stress resistance and competitiveness in the phyllosphere in a naturally abundant plant epiphyte, Sphingomonas sp. strain Fr1, and provide evidence that the partner switching mechanism is conserved. We furthermore identify a gene, designated phyP, encoding a predicted histidine kinase at the phyR locus as essential. Genetic epistasis experiments suggest that PhyP acts upstream of PhyR, keeping PhyR in an unphosphorylated, inactive state in nonstress conditions, strictly depending on the predicted phosphorylatable site of PhyP, His-341. In vitro experiments show that Escherichia coli inner membrane fractions containing PhyP disrupt the PhyR-P/NepR complex. Together with the fact that PhyP lacks an obvious ATPase domain, these results are in agreement with PhyP functioning as a phosphatase of PhyR, rather than a kinase. PMID:21949070
Kaczmarczyk, Andreas; Campagne, Sébastien; Danza, Francesco; Metzger, Lisa C; Vorholt, Julia A; Francez-Charlot, Anne
2011-12-01
The general stress response in Alphaproteobacteria was recently described to depend on the alternative sigma factor σ(EcfG), whose activity is regulated by its anti-sigma factor NepR. The response regulator PhyR, in turn, regulates NepR activity in a partner-switching mechanism according to which phosphorylation of PhyR triggers sequestration of NepR by the sigma factor-like effector domain of PhyR. Although genes encoding predicted histidine kinases can often be found associated with phyR, little is known about their role in modulation of PhyR phosphorylation status. We demonstrate here that the PhyR-NepR-σ(EcfG) cascade is important for multiple stress resistance and competitiveness in the phyllosphere in a naturally abundant plant epiphyte, Sphingomonas sp. strain Fr1, and provide evidence that the partner switching mechanism is conserved. We furthermore identify a gene, designated phyP, encoding a predicted histidine kinase at the phyR locus as essential. Genetic epistasis experiments suggest that PhyP acts upstream of PhyR, keeping PhyR in an unphosphorylated, inactive state in nonstress conditions, strictly depending on the predicted phosphorylatable site of PhyP, His-341. In vitro experiments show that Escherichia coli inner membrane fractions containing PhyP disrupt the PhyR-P/NepR complex. Together with the fact that PhyP lacks an obvious ATPase domain, these results are in agreement with PhyP functioning as a phosphatase of PhyR, rather than a kinase.
A finite element study of a lumbar motion segment subjected to pure sagittal plane moments.
Shirazi-Adl, A; Ahmed, A M; Shrivastava, S C
1986-01-01
A nonlinear finite element program has been developed and applied to the analysis of a three-dimensional model of the lumbar L2-3 motion segment subjected to sagittal plane moments. The analysis accounts for both material and geometric nonlinearities and is based on the Updated Lagrangian approach. The disc nucleus has been considered as an incompressible inviscid fluid and the annulus as a composite of collagenous fibres embedded in a matrix of ground substance. Articulation at the facet joints has been treated as a general moving contact problem and the spinal ligaments have been modelled as a collection of nonlinear axial elements. Effects of the loss of intradiscal pressure in flexion and of facetectomy in extension have been analyzed. Comparison of the predicted gross response characteristics with available measurements indicates satisfactory agreement. In flexion relatively large intradiscal pressures are generated, while in extension negative pressures (i.e. suction) of low magnitude are predicted. The stress distribution results indicate that the load transfer path through the posterior elements of the joint in flexion is different from that in extension. In flexion the ligaments are the means of load transfer, while in extension the load is transmitted through the pedicles, laminae and articular processes. In flexion, the inner annulus fibres at the posterolateral location are subject to maximum tensile strain. It is suggested that large flexion moment in combination with other loads is a likely cause of disc prolapse commonly found at this location of the annulus.
Complex space monofilar approximation of diffraction currents on a conducting half plane
NASA Technical Reports Server (NTRS)
Lindell, I. V.
1987-01-01
Simple approximation of diffraction surface currents on a conducting half plane, due to an incoming plane wave, is obtained with a line current (monofile) in complex space. When compared to an approximating current at the edge, the diffraction pattern is seen to improve by an order of magnitude for a minimal increase of computation effort. Thus, the inconvient Fresnel integral functions can be avoided for quick calculations of diffracted fields and the accuracy is good in other directions than along the half plane. The method can be applied to general problems involving planar metal edges.
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.
Biomechanical differences between incline and plane hopping.
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.
NASA Astrophysics Data System (ADS)
Moutanabbir, O.; Reiche, M.; Erfurth, W.; Naumann, F.; Petzold, M.; Gösele, U.
2009-06-01
The strain behavior in nanoscale patterned biaxial tensile strained Si layer on insulator is investigated in 60-nm-thick nanostructures with dimensions in the 80-400 nm range. The in-plane strain is evaluated by using UV micro-Raman. We found that less than 30% of the biaxial strain is maintained in the 200×200 nm2 nanostructures. This relaxation, due to the formation of free surfaces, becomes more important in smaller nanostructures. The strain is completely relieved at 80 nm. This phenomenon is described based on detailed three-dimensional finite element simulations. The anisotropic relaxation in rectangular nanostructures is also discussed.
Hopper, R.W.
1984-12-01
The coalescence of two equal viscous cylinders under the influence of capillarity is of interest in the theory of sintering. Although the flow in typical cylinder coalescence experiments is not planar, the plane-flow case is of general interest and is a good approximation in the early stage. An essentially exact analytic solution giving the shape as a function of time for slow plane flow is presented in simple closed form. 16 references, 2 figures, 1 table.
Hopper, R.W.
1984-12-01
The coalescence of two equal viscous cylinders under the influence of capillarity is of interest in the theory of sintering. Although the flow in typical cylinder coalescence experiments is not planar, the plane-flow case is of general interest and is a good approximation in the early stage. An essentially exact analytic solution giving the shape as a function of time for slow plane flow is presented in simple closed form. 15 references, 2 figures, 1 table.
Geometric structure of pseudo-plane quadratic flows
NASA Astrophysics Data System (ADS)
Sun, Che
2017-03-01
Quadratic flows have the unique property of uniform strain and are commonly used in turbulence modeling and hydrodynamic analysis. While previous applications focused on two-dimensional homogeneous fluid, this study examines the geometric structure of three-dimensional quadratic flows in stratified fluid by solving a steady-state pseudo-plane flow model. The complete set of exact solutions reveals that steady quadratic flows have an invariant conic type in the non-rotating frame and a non-rotatory vertical structure in the rotating frame. Three baroclinic solutions with vertically non-aligned formulation disprove an earlier conjecture. All elliptic and hyperbolic solutions, except for the inertial ones, exhibit vertical concentricity. The rich geometry of quadratic flows stands in contrast to the depleted geometry of high-degree polynomial flows. A paradox in the steady solutions of shallow-water reduced-gravity models is also explained.
INTERIOR OF SECOND FLOOR BRIDGE BETWEEN PLANING MILL AND CAR ...
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
Integrable mappings of the plane preserving biquadratic invariant curves
NASA Astrophysics Data System (ADS)
Iatrou, Apostolos; Roberts, John A. G.
2001-08-01
We provide a general framework to construct integrable mappings of the plane that preserve a one-parameter family B(x,y,K) of biquadratic invariant curves where parametrization by K is very general. These mappings are reversible by construction (i.e. they are the composition of two involutions) and can be shown to be measure preserving. They generalize integrable maps previously given by McMillan and Quispel, Roberts and Thompson. By considering a transformation of the case of the symmetric biquadratic to a canonical form, we provide a normal form for the symmetric integrable map acting on each invariant curve. We give a Lax pair for a large subclass of our symmetric integrable maps, including at least a 10-parameter subfamily of the 12-parameter symmetric Quispel-Roberts-Thompson maps.
GPR study of bedding planes, fractures, and cavities in limestone
NASA Astrophysics Data System (ADS)
Pipan, M.; Baradello, L.; Forte, E.; Prizzon, A.
2000-04-01
We performed a multi-fold GPR study at a Cretaceous-Tertiary (K-T) outcrop in limestone layers of the Peri-Adriatic carbonatic platform, Italy). Primary objective of the study was imaging of the K-T contact and mapping of localized depth variations in a general framework of homoclinical limestone layers. A secondary objective was the study of faults, fractures and cavities of interest for engineering purposes. A combination of 2-D and 3-D multifold techniques was used to image and map structural and stratigraphic features. A 200 sqm grid was surveyed with 1 meter cross-line spacing and 5 cm in- line trace interval. The K-T contact is electromagnetically transparent, and it is actually deduced from paleontologic evidence. Due to the homoclinal trend, K-T topography is reconstructed from the bedding planes bounding the contact. Fractures antithetic to bedding planes are imaged by 2-D stack and migrated profiles. Part of the fractures can be considered small transtensional faults. The results obtained provide the first geophysical evidence of small-scale transtensive deformation in the area. Curvilinear radar reflector, intersecting the homoclinal bedding planes, are imaged in faulted zones and are possibly related to limestone buildups. A fractured rock volume develops into a cavity with average estimated section of a 4 sqm.
The identification of coordination constraints across planes of motion.
Serrien, D J; Bogaerts, H; Suy, E; Swinnen, S P
1999-09-01
Two dominant coordination constraints have been identified during isofrequency conditions in previous work: the egocentric constraint, i.e., simultaneous activation of homologous muscle groups, and the allocentric constraint, i.e., moving the segments in the same direction in extrinsic space. To verify their generalization, bimanual drawing movements were performed in different planes of motion (transverse, frontal, sagittal, frontal-transverse) according to the in-phase and anti-phase mode along the X- and Y-axes. Convergent findings were obtained across the transverse, frontal, and frontal-transverse planes. The in-phase mode along both axes was performed most accurately/consistently, whereas the anti-phase mode resulted in a deterioration of the coordination pattern and this effect was most pronounced when the latter mode was introduced with respect to both dimensions. For sagittal plane motions, the in-phase mode was again superior but the second most optimal configuration was the anti-phase mode along both axes. This finding was hypothesized to result from the familiarity with the pattern since it resembles cycling behavior. It illustrates how cognitive mapping is superimposed onto the dynamics of interlimb coordination. Overall, these results support the presence of both the egocentric and allocentric constraint during bimanual movement production.
In-Plane Optical Anisotropy of Layered Gallium Telluride.
Huang, Shengxi; Tatsumi, Yuki; Ling, Xi; Guo, Huaihong; Wang, Ziqiang; Watson, Garrett; Puretzky, Alexander A; Geohegan, David B; Kong, Jing; Li, Ju; Yang, Teng; Saito, Riichiro; Dresselhaus, Mildred S
2016-09-27
Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C2h(3) space group. Investigating the in-plane optical anisotropy, including the electron-photon and electron-phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics. In this work, the anisotropic light-matter interactions in the low-symmetry material GaTe are studied using anisotropic optical extinction and Raman spectroscopies as probes. Our polarized optical extinction spectroscopy reveals the weak anisotropy in optical extinction spectra for visible light of multilayer GaTe. Polarized Raman spectroscopy proves to be sensitive to the crystalline orientation of GaTe, and shows the intricate dependences of Raman anisotropy on flake thickness, photon and phonon energies. Such intricate dependences can be explained by theoretical analyses employing first-principles calculations and group theory. These studies are a crucial step toward the applications of GaTe especially in optoelectronics and thermoelectrics, and provide a general methodology for the study of the anisotropy of light-matter interactions in 2D layered materials with in-plane anisotropy.
In-plane optical anisotropy of layered gallium telluride
Huang, Shengxi; Tatsumi, Yuki; Ling, Xi; ...
2016-08-16
Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C2h3 space group. Investigating the in-plane optical anisotropy, including the electron–photon and electron–phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics. In this work, the anisotropic light-matter interactions in the low-symmetry material GaTe are studied using anisotropic optical extinction and Raman spectroscopies as probes. Our polarized optical extinction spectroscopy reveals the weak anisotropy in opticalmore » extinction spectra for visible light of multilayer GaTe. Polarized Raman spectroscopy proves to be sensitive to the crystalline orientation of GaTe, and shows the intricate dependences of Raman anisotropy on flake thickness, photon and phonon energies. Such intricate dependences can be explained by theoretical analyses employing first-principles calculations and group theory. Furthermore, these studies are a crucial step toward the applications of GaTe especially in optoelectronics and thermoelectrics, and provide a general methodology for the study of the anisotropy of light-matter interactions in 2D layered materials with in-plane anisotropy.« less
In-plane optical anisotropy of layered gallium telluride
Huang, Shengxi; Tatsumi, Yuki; Ling, Xi; Guo, Huaihong; Wang, Ziqiang; Watson, Garrett; Puretzky, Alexander A.; Geohegan, David B.; Kong, Jing; Li, Ju; Yang, Teng; Saito, Riichiro; Dresselhaus, Mildred S.
2016-08-16
Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C_{2h}^{3} space group. Investigating the in-plane optical anisotropy, including the electron–photon and electron–phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics. In this work, the anisotropic light-matter interactions in the low-symmetry material GaTe are studied using anisotropic optical extinction and Raman spectroscopies as probes. Our polarized optical extinction spectroscopy reveals the weak anisotropy in optical extinction spectra for visible light of multilayer GaTe. Polarized Raman spectroscopy proves to be sensitive to the crystalline orientation of GaTe, and shows the intricate dependences of Raman anisotropy on flake thickness, photon and phonon energies. Such intricate dependences can be explained by theoretical analyses employing first-principles calculations and group theory. Furthermore, these studies are a crucial step toward the applications of GaTe especially in optoelectronics and thermoelectrics, and provide a general methodology for the study of the anisotropy of light-matter interactions in 2D layered materials with in-plane anisotropy.
In-plane optical anisotropy of layered gallium telluride
Huang, Shengxi; Tatsumi, Yuki; Ling, Xi; Guo, Huaihong; Wang, Ziqiang; Watson, Garrett; Puretzky, Alexander A.; Geohegan, David B.; Kong, Jing; Li, Ju; Yang, Teng; Saito, Riichiro; Dresselhaus, Mildred S.
2016-08-16
Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C_{2h}^{3} space group. Investigating the in-plane optical anisotropy, including the electron–photon and electron–phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics. In this work, the anisotropic light-matter interactions in the low-symmetry material GaTe are studied using anisotropic optical extinction and Raman spectroscopies as probes. Our polarized optical extinction spectroscopy reveals the weak anisotropy in optical extinction spectra for visible light of multilayer GaTe. Polarized Raman spectroscopy proves to be sensitive to the crystalline orientation of GaTe, and shows the intricate dependences of Raman anisotropy on flake thickness, photon and phonon energies. Such intricate dependences can be explained by theoretical analyses employing first-principles calculations and group theory. Furthermore, these studies are a crucial step toward the applications of GaTe especially in optoelectronics and thermoelectrics, and provide a general methodology for the study of the anisotropy of light-matter interactions in 2D layered materials with in-plane anisotropy.
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.
Exhumation by gravitational sliding up an inclined plane
NASA Astrophysics Data System (ADS)
Podladchikov, Yury; Schmalholz, Stefan; Burg, Jean-Pierre
2015-04-01
Gravity causes sliding down an inclined plane if pressure is near lithostatic. If metamorphic pressures are lithostatic pressures, the approximation is inconsistent with pressure-temperature exhumation histories of thrust nappes stacked during compression to form the thickened crust of mountain belts. Overthickened mountain roots and foreland basin-type sedimentation accompanying the downward movement component of the Moho require significant non-lithostatic pressure perturbations within the mountain belts. Relaxation of the subsequent pressure gradients can be achieved by nappe-like thrusting up an inclined plane recording near isothermal decompression and carrying young sediments to high altitudes. We present results of fully dynamic numerical modelling documenting feasibility of this process. Neither thrusting, nor large weakness zones nor S-point-type boundary conditions are kinematically prescribed in our models. Thrusting emerges spontaneously as an instability, strain localization process that may follow preexisting lithological layering or thermal gradients and able to form new zones of weakness by shear heating mechanism. The non-prescribed nature of our modeled deformation modes makes them feasible, even probable as a leading response to continental shortening. In that case, non lithostatic pressure 'cycle' is an alternative or a complement to the classical Wilson cycle invoked alone to explain elevated occurrences of deep-water sediments.
Creep Behavior of Organic-Rich Shales - Evidences of Microscale Strain Partitioning
NASA Astrophysics Data System (ADS)
Sone, H.; Morales, L. F. G.; Dresen, G. H.
2015-12-01
Laboratory creep experiments conducted using organic-rich shales show that these rocks exhibit some ductility under sustained loading conditions although they may appear to be elastic and brittle (Young's modulus 15-80 GPa) at shorter time scales. At room-temperature and in-situ pressure conditions, creep strain observed after 3 hours of sustained loading reach strains on the order of 10-5per megapascal of applied differential stress. The creep behavior is highly anisotropic such that creep occurs more in the direction perpendicular to the bedding plane than in the direction parallel to the bedding plane. In general, we find that the creep behavior is largely controlled by the amount of clay mineral and organic content. This is also supported by evidences of elastic stiffening and sample volume reduction during creep which imply that the creep is accommodated by localized compaction occurring within clay-aggregates and/or organic materials, the relatively porous members in the rock. We also find that the tendency to creep has a unique relation with the Young's modulus regardless of the loading direction or the mineral composition. Sone and Zoback (2013) explained this correlation by appealing to the stress partitioning behavior that occurs between the relatively stiff and soft components of the rock, and also by assuming that creep only occurs within the soft components, namely the clay and organic contents, with a specific local 3-hour creep compliance value of 10-4 MPa-1. In order to confirm that such strain-partitioning occurs during creep deformation, we also performed creep experiments under a scanning electron microscope using a deformation stage setup. Such experiments allow us to directly observe the deformation and quantify the strain-partitioning occurring between the different mineral constituents with the aid of digital image correlation analysis. Results suggest that strain-partitioning do occur during creep deformation and inferred creep properties of
BaO Planes, not CuO2 Planes, Contain HIGH-TC Superconductivity
NASA Astrophysics Data System (ADS)
Dow, John D.; Harshman, Dale R.
Muon spin rotation (μ+SR) measurements conducted on crystalline YBa2Cu3O7 are consistent with s-wave pairing, not d-wave, suggesting that the superconducting hole condensate resides in the BaO layers, not in the cuprate-planes. The specific heat and thermal conductivity data are explained by the superconducting BaO layers alone, unlike the failed interpretation based on CuO2-plane superconductivity. The layer charges of the CuO2 planes are almost -2 |e|, indicating that those planes are primarily carriers of electrons, not holes. The cuprate-planes are not the dominant hole-carriers of high-TC superconductivity, as demonstrated by doped YBa2RuO6, which has no such CuO2 lanes, yet superconducts at ~ 93 K. Moreover the trio of related compounds, YSr2RuO6 (doped with Cu on Ru sites), undoped GdSr2Cu2RuO8, and undoped Gd2-zCezSr2Cu2RuO10 all start superconducting near 49 K in their SrO layers, not in the cuprate planes of the two compounds that have such planes, because those planes are either antiferromagnetic or weakly ferromagnetic and so do not superconduct. In PrBa2Cu3O7, a Pr-on-Ba-site (PrBa) defect kills the superconductivity, but Pr-on-Pr-site (PrPr) does not. Both defects are approximately equidistant from the intervening cuprate plane, suggesting that the cuprate plane does not carry significant superconductivity. In GdBa2Cu3O7, Gd-on-a-Gd-site (GdGd) does not break Cooper pairs, but Gd-on-a-Ba-site (GdBa) does, indicating that the superconductivity is in the BaO layers, and not in the cuprate-planes. In HgBa2Can-1CunO2n+2, the BaO layers, not the cuprate-planes, gain positive charge as TC, pressure, and the number of layers n increase. The reason that theories based on holes in the cuprate-planes have done so poorly is that those planes were incorrectly identified as the source of high-temperature superconductivity on the basis of a single datum by Cava et al., that was first contradicted by Jorgensen et al., and then endorsed by Jorgensen alone on the
Achieving control of in-plane elastic waves
NASA Astrophysics Data System (ADS)
Brun, M.; Guenneau, S.; Movchan, A. B.
2009-02-01
We derive the elastic properties of a cylindrical cloak for in-plane coupled shear and pressure waves. The cloak is characterized by a rank 4 elasticity tensor with spatially varying entries, which are deduced from a geometric transform. Remarkably, the Navier equations retain their form under this transform, which is generally untrue [G. W. Milton et al., N. J. Phys. 8, 248 (2006)]. The validity of our approach is confirmed by comparison of the analytic Green's function in homogeneous isotropic elastic space against full-wave finite element computations in a heterogeneous anisotropic elastic region surrounded by perfectly matched layers.
The Synthesis of Stable Grasps in the Plane.
1985-10-01
ft-AIG5 903 THE SYNTHESIS OF STABLE GRASPS IN THE PLANE(U) / MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB V NGUYEN OCT 85 AI-M...assembly operations become easier and less sensitive to errors. -4 ’I MASSACIIUSI’TS INST’I’TI,’ O1 ’IINOIOGY ARTIIFICIAL IN’i’II(I’N(’I AI)ItA’i’ORY...Acknowledgments: This report describes research done at the General Mo- tors Research Laboratories and at the Artificial Intelligence Laboratory of the Mas
The MSX Galactic Plane Survey Submillimeter Results
NASA Astrophysics Data System (ADS)
Price, S.; Carey, S.; Egan, M. P.
The MidCourse Space eXperiment (MSX) surveyed the Galactic plane within 5° latitude in four mid-infrared spectral bands. A set of full resolution (20'') 1.5^circ×1.5^circ images on 6'' pixel centers has been created in each spectral band by co-adding all the survey data. A lower (1.2') resolution atlas of 10^circ×10^circ images provide large-scale panoramas of the plane. A new class of objects has been identified in the images, infrared dark clouds, which are silhouetted against the mid-infrared background emission from the interstellar medium in the Galactic plane. The IRAS ISSA plates indicate that these clouds are dark out to 100 μm. Submillimeter emission traces the form of the dark cloud and reveals cores indicative of class 0 protostars.
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.
Achromatic phase shifting focal plane masks
NASA Astrophysics Data System (ADS)
Newman, Kevin
The search for life on other worlds is an exciting scientific endeavor that could change the way we perceive our place in the universe. Thousands of extrasolar planets have been discovered using indirect detection techniques. One of the most promising methods for discovering new exoplanets and searching for life is direct imaging with a coronagraph. Exoplanet coronagraphy of Earth-like planets is a challenging task, but we have developed many of the tools necessary to make it feasible. The Phase-Induced Amplitude Apodization (PIAA) Coronagraph is one of the highest-performing architectures for direct exoplanet imaging. With a complex phase-shifting focal plane mask, the PIAA Complex Mask Coronagraph (PIAACMC) can approach the theoretical performance limit for any direct detection technique. The architecture design is flexible enough to be applied to any arbitrary aperture shape, including segmented and obscured apertures. This is an important feature for compatibility with next-generation ground and space-based telescopes. PIAA and PIAACMC focal plane masks have been demonstrated in monochromatic light. An important next step for high-performance coronagraphy is the development of broadband phase-shifting focal plane masks. In this dissertation, we present an algorithm for designing the PIAA and PIAACMC focal plane masks to operate in broadband. We also demonstrate manufacturing of the focal plane masks, and show laboratory results. We use simulations to show the potential performance of the coronagraph system, and the use of wavefront control to correct for mask manufacturing errors. Given the laboratory results and simulations, we show new areas of exoplanet science that can potentially be explored using coronagraph technology. The main conclusion of this dissertation is that we now have the tools required to design and manufacture PIAA and PIAACMC achromatic focal plane masks. These tools can be applied to current and future telescope systems to enable new
Staring Focal Plane Array System Modeling
1989-12-01
C’, DTIC SELECTENI ODEC271 D B mU STARING FOCAL PLANE ARRAY SYSTEM MODELING THESIS John Gerard Murphy Captain, USAF AFIT/GEO/ENP/89D- 3 DEPARTMENT OF...m mmmmmmmm .. \\FlIT/GEO/ENP/89D- 3 STARING FOCAL PLANE ARRAY SYSTEM MODELING THESIS Presented to the Faculty of the School of Engineering of the Air...Background. .. .. ... ... .... ... .... ..... 1-2 1.1.1 MRTD .. .. .. ... ... .... .... ..... 1-2 01.1.2 MIRTD in Modeling. .. .. .. ... .... .... 1- 3 113MRTD
[Normolipemic plane xanthomas and mycosis fungoides].
García-Arpa, Mónica; Rodríguez-Vázquez, María; Vera, Elena; Romero, Guillermo; González-García, Jesús; Cortina, Pilar
2005-06-01
Diffuse normolipemic plane xanthomas are characterized by the presence of yellowish plaques on the eyelids, neck, upper trunk, buttocks and flexures. Histology shows foamy histiocytes in the dermis. Approximately half of all cases are associated with hematological disorders. On rare occasions, they have been described in the context of cutaneous T-cell lymphomas. We present the case of a female patient with tumor-stage mycosis fungoides who developed normolipemic plane xanthomas coinciding with the appearance of new lymphoma lesions. We review English-language literature regarding the rare association of xanthomas and cutaneous T-cell lymphomas.
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.
Slant plane CSAR processing using Householder transform.
Burki, Jehanzeb; Barnes, Christopher F
2008-10-01
Fourier analysis-based focusing of synthetic aperture radar (SAR) data collected during circular flight path is a recent advancement in SAR signal processing. This paper uses the Householder transform to obtain a ground plane circular SAR (CSAR) signal phase history from the slant plane CSAR phase history by inverting the linear shift-varying system model, thereby circumventing the need for explicitly computing a pseudo-inverse. The Householder transform has recently been shown to have improved error bounds and stability as an underdetermined and ill-conditioned system solver, and the Householder transform is computationally efficient.
Toward loop quantization of plane gravitational waves
NASA Astrophysics Data System (ADS)
Hinterleitner, Franz; Major, Seth
2012-03-01
The polarized Gowdy model in terms of Ashtekar-Barbero variables is reduced with an additional constraint derived from the Killing equations for plane gravitational waves with parallel rays. The new constraint is formulated in a diffeomorphism invariant manner and, when it is included in the model, the resulting constraint algebra is first class, in contrast to the prior work done in special coordinates. Using an earlier work by Banerjee and Date, the constraints are expressed in terms of classical quantities that have an operator equivalent in loop quantum gravity, making these plane gravitational wave spacetimes accessible to loop quantization techniques.
Comparison of interferometric spectral imaging techniques near the pupil plane and image plane
NASA Astrophysics Data System (ADS)
Itoh, Kazuyoshi; Inoue, Takashi; Ichioka, Yoshiki
1990-07-01
We present an analysis of signal to noise ratios of two interferometric techniques for spectral imaging and its experimental verification. One technique makes use of interference signals detected near the pupil plane and the other uses the signals near the image plane. The experiments showed that the latter technique is superior to the former under the normal conditions. 1.
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.
Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains
Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.
2015-01-01
Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869
Benito, L; Ciria, M; de la Fuente, C; Arnaudas, J I; Ward, R C C; Wells, M R
2005-06-10
We report on the change of the easy axis direction in holmium, from the a to the b axis, under the application of a magnetic field in the basal plane. This spin reorientation is observed by measuring the magnetic torque in Ho(n)/Lu(15) superlattices (n and 15 are the number of atomic planes in the Ho and Lu blocks). We also observe that, at the field H0 and temperature at which the reorientation occurs, both axes are easy directions. Based on the fact that the field H0 depends on n in the same way as the field-induced magnetoelastic distortion does, we propose that this spin reorientation originates from the strong field-induced magnetoelastic deformation within the basal plane. The modulation of the alpha strains with sixfold symmetry originates a 12-fold term in the magnetic anisotropy energy.
Numerical Simulation of Dislocation Interactions in Strained Layers
NASA Astrophysics Data System (ADS)
Schwarz, Klaus W.
1998-03-01
Because both the dynamics and the interactions of dislocations are complicated, little is known about the effects that individual dislocations have on each other when they come into close proximity, and, more generally, about the evolution of collections of strongly interacting dislocations. The power of modern supercomputers allows one to address these issues by direct numerical simulation. In our program the stress tensor which moves the dislocations is calculated at every point by evaluating the full Peach-Koehler expression over all of the dislocations present. The self-interaction of the dislocations is regularized by the Brown method of splitting the dislocation in half, moving the two halves outward by some core parameter, and averaging the result. The code can be used to study the interactions between arbitrarily configured dislocations, located on any allowed glide plane, passing from one glide plane to another, and having any allowed Burgers vector, and has been applied to model the behavior of dislocations in semiconducting thin films. The behavior of a threading dislocation as it tries to pass over a misfit dislocation in the layer interface has been investigated, and the blocking effect of the misfit is found to be considerably less than previously estimated. Subsequent studies have calculated the behavior of Frank-Read sources, spiral sources, and corner sources in a strained layer, as well as that of multiple sources operating on various glide planes. For a model in which the layer is assumed to relax through the excitation of a low density of Frank-Read sources, it is found that the interactions between the emitted dislocations result in elaborate dislocation networks. The predicted patterns are strikingly similar to those observed in actual relaxed layers.
Optical measurement on dynamic buckling behavior of stiffened composite panels under in-plane shear
NASA Astrophysics Data System (ADS)
Lei, Zhenkun; Bai, Ruixiang; Tao, Wang; Wei, Xiao; Leng, Ruijiao
2016-12-01
The buckling behavior and failure mode of a composite panel stiffened by I-shaped stringers under in-plane shear is studied using digital fringe projection profilometry. The basic principles of the dynamic phase-shifting technique, multi-frequency phase-unwrapping technique and inverse-phase technique for nonlinear error compensation are introduced. Multi-frequency fringe projection profilometry was used to monitor and measure the change in the morphology of a discontinuous surface of the stiffened composite panel during in-plane shearing. Meanwhile, the strain history of multiple points on the skin was obtained using strain rosettes. The buckling mode and deflection of the panel at different moments were analyzed and compared with those obtained using the finite element method. The experimental results validated the FEM analysis.
NASA Technical Reports Server (NTRS)
Zhang, Wang; Binienda, Wieslaw K.; Pindera, Marek-Jerzy
1997-01-01
A previously developed local-global stiffness matrix methodology for the response of a composite half plane, arbitrarily layered with isotropic, orthotropic or monoclinic plies, to indentation by a rigid parabolic punch is further extended to accommodate the presence of layers with complex eigenvalues (e.g., honeycomb or piezoelectric layers). First, a generalized plane deformation solution for the displacement field in an orthotropic layer or half plane characterized by complex eigenvalues is obtained using Fourier transforms. A local stiffness matrix in the transform domain is subsequently constructed for this class of layers and half planes, which is then assembled into a global stiffness matrix for the entire multilayered half plane by enforcing continuity conditions along the interfaces. Application of the mixed boundary condition on the top surface of the half plane indented by a rigid punch results in an integral equation for the unknown pressure in the contact region. The integral possesses a divergent kernel which is decomposed into Cauchy-type and regular parts using the asymptotic properties of the local stiffness matrix and a relationship between Fourier and finite Hilbert transform of the contact pressure. The solution of the resulting singular integral equation is obtained using a collocation technique based on the properties of orthogonal polynomials developed by Erdogan and Gupta. Examples are presented that illustrate the important influence of low transverse properties of layers with complex eigenvalues, such as those exhibited by honeycomb, on the load versus contact length response and contact pressure distributions for half planes containing typical composite materials.
O'Leary, Shaun; Christensen, Steffan W; Verouhis, Alexis; Pape, Morten; Nilsen, Oivind; McPhail, Steven M
2015-12-01
Evaluation of scapular posture is an integral component of the clinical assessment of painful neck disorders. The aim of this study was to evaluate agreement between therapist judgements of scapula posture in multiple biomechanical planes in individuals with neck pain. Inter-therapist reliability study. Research laboratory. Fifteen participants with chronic neck pain. Four physiotherapists recorded ratings of scapular orientation (relative to the thorax) in five different scapula postural planes (plane of scapula, sagittal plane, transverse plane, horizontal plane, and vertical plane) under four test conditions (at rest, and during three isometric shoulder conditions) in all participants. Inter-therapist reliability was expressed using both generalized and paired kappa coefficient. Following adjustment for expected agreement and the high prevalence of neutral ratings (81%), on average both the generalised kappa (0.37) as well as Cohen's Kappa for the two therapist pairs (0.45 and 0.42) demonstrated only slight to moderate inter-therapist reliability. The findings suggest that ratings of scapular posture in individuals with neck pain by visual inspection has only slight to moderate reliability and should only be used in conjunction with other clinical tests when judging scapula function in these patients. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.
MTI Focal Plane Assembly Design and Performance
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.
VLBI Ecliptic Plane Survey: VEPS-1
NASA Astrophysics Data System (ADS)
Shu, Fengchun; Petrov, Leonid; Jiang, Wu; Xia, Bo; Jiang, Tianyu; Cui, Yuzhu; Takefuji, Kazuhiro; McCallum, Jamie; Lovell, Jim; Yi, Sang-oh; Hao, Longfei; Yang, Wenjun; Zhang, Hua; Chen, Zhong; Li, Jinling
2017-06-01
We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within 7\\buildrel{\\circ}\\over{.} 5 of the ecliptic plane that are suitable as calibrators for anticipated phase referencing observations of spacecraft, and determine their positions with accuracy at the 1.5 nrad level. We run the program in two modes: search and refine. In the search mode, a complete sample of all sources brighter than 50 mJy at 5 GHz listed in the Parkes-MIT-NRAO and Green Bank 6 cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By 2016 October, thirteen 24 hr sessions that targeted all sources brighter than 100 mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.
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.
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.
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.
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.
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.
Deep-Plane Lipoabdominoplasty in East Asians
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
Selective plane illumination microscopy on a chip.
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.
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)
Spatial Reasoning and Polya's Five Planes Problem
ERIC Educational Resources Information Center
Madden, Sean P.; Diaz, Ricardo
2008-01-01
Middle and High school students of the twenty-first century possess surprising powers of spatial reasoning. They are assisted by technologies not available to earlier generations. Both of these assertions are demonstrated by students who are challenged with George Polya's classic Five Planes Problem. (Contains 5 figures.)
Optical interconnections to focal plane arrays
Rienstra, J.L.; Hinckley, M.K.
2000-11-01
The authors have successfully demonstrated an optical data interconnection from the output of a focal plane array to the downstream data acquisition electronics. The demonstrated approach included a continuous wave laser beam directed at a multiple quantum well reflectance modulator connected to the focal plane array analog output. The output waveform from the optical interconnect was observed on an oscilloscope to be a replica of the input signal. They fed the output of the optical data link to the same data acquisition system used to characterize focal plane array performance. Measurements of the signal to noise ratio at the input and output of the optical interconnection showed that the signal to noise ratio was reduced by a factor of 10 or more. Analysis of the noise and link gain showed that the primary contributors to the additional noise were laser intensity noise and photodetector receiver noise. Subsequent efforts should be able to reduce these noise sources considerably and should result in substantially improved signal to noise performance. They also observed significant photocurrent generation in the reflectance modulator that imposes a current load on the focal plane array output amplifier. This current loading is an issue with the demonstrated approach because it tends to negate the power saving feature of the reflectance modulator interconnection concept.
End Site Control Plane Subsystem (ESCPS)
Swany, Douglas Martin
2014-08-12
This project researched extending the control plane for dynamic networks into end sites like campuses and laboratories. Key aspects of consideration were signaling over local area network technologies, application integration and monitoring. We studied design considerations for such environments and developed and demonstrated a useful proof of concept implementation and documented implementation strategies for heterogeneous networks.
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)
Huang, H. B.; Hu, J. M.; Yang, T. N.; Chen, L. Q.; Ma, X. Q.
2014-09-22
Effect of substrate misfit strain on current-induced in-plane magnetization reversal in CoFeB-MgO based magnetic tunnel junctions is investigated by combining micromagnetic simulations with phase-field microelasticity theory. It is found that the critical current density for in-plane magnetization reversal decreases dramatically with an increasing substrate strain, since the effective elastic field can drag the magnetization to one of the four in-plane diagonal directions. A potential strain-assisted multilevel bit spin transfer magnetization switching device using substrate misfit strain is also proposed.
NASA Astrophysics Data System (ADS)
Park, Chang Bum; Na, HyungIl; Yoo, Soon Sung; Park, Kwon-Shik
2015-11-01
The electromechanical response of an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) fabricated on a polyimide substrate was investigated as a function of the neutral axis location and strain history of the bending system. Here, we demonstrate the pronounced bending characteristics of a-IGZO TFTs and their backplane under extreme mechanical strain when they are embedded in a neutral plane (NP). After being subjected to tensile stress, the devices positioned near the NP were observed to function well against a cyclic bending stress of 2 mm radius with 100,000 times, while TFTs farther from the neutral surface exhibited modified electrical properties.
Canting of the occlusal plane: perceptions of dental professionals and laypersons.
Olivares, Amparo; Vicente, Ascensión; Jacobo, Carmen; Molina, Sara-María; Rodríguez, Alicia; Bravo, Luis-Alberto
2013-05-01
To determine if canting of the occlusal plane influences esthetic evaluation of the smile among orthodontists, dentists and laypersons. A frontal photo of a smile with 0 occlusal plane canting in relation to the bipupillary plane was modified using Adobe Photoshop C3 (Adobe Systems Inc, San José, California) to generate two images with occlusal plane inclinations of 2 and 4 . The three images were evaluated esthetically by orthodontists (n=40) general dentists (n=40) and laypersons (n=40). Each image was awarded a score as follows: 1=esthetically acceptable; 2=moderately acceptable; 3=esthetically unacceptable. Evaluators also placed the three images in order in preference. Data were analyzed using the Kruskal-Wallis (p<0.05) and the Mann-Whitney tests, applying the Bonferroni Correction (p<0.016). No significant differences (p> 0.05) were found between the three groups for 0 and 2 cants (median for orthodontists=1; general dentists=1; laypersons=1). Orthodontists (median score=3) made evaluations of the image with 4 occlusal plane that were significantly different from general dentists (median=2) and laypersons (median=2). All three groups put the 0 image in first place in order of esthetic acceptability, the 2 image in second place and the 4 image in third place. Orthodontists placed the 0 image in first place with significantly greater frequency (p<0.016) than laypersons. Occlusal plane canting of 0 and 2 were evaluated as esthetically acceptable by the three groups. The 4 occlusal plane cant was evaluated more negatively by orthodontists than by general dentists and laypersons. All three groups placed the 0 image in first place of esthetic acceptability, 2 in second place and 4 in third. Orthodontists put the 0 image in first place with significantly greater frequency than laypersons.
Multifocal planes head-mounted displays.
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.
In-plane vibration analysis of annular plates with arbitrary boundary conditions.
Shi, Xianjie; Shi, Dongyan; Qin, Zhengrong; Wang, Qingshan
2014-01-01
In comparison with the out-of-plane vibrations of annular plates, far less attention has been paid to the in-plane vibrations which may also play a vital important role in affecting the sound radiation from and power flows in a built-up structure. In this investigation, a generalized Fourier series method is proposed for the in-plane vibration analysis of annular plates with arbitrary boundary conditions along each of its edges. Regardless of the boundary conditions, the in-plane displacement fields are invariantly expressed as a new form of trigonometric series expansions with a drastically improved convergence as compared with the conventional Fourier series. All the unknown expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. Unlike most of the existing studies, the presented method can be readily and universally applied to a wide spectrum of in-plane vibration problems involving different boundary conditions, varying material, and geometric properties with no need of modifying the basic functions or adapting solution procedures. Several numerical examples are presented to demonstrate the effectiveness and reliability of the current solution for predicting the in-plane vibration characteristics of annular plates subjected to different boundary conditions.
Rupture Plane Determination of Small to Moderate Earthquakes by Finite Moment Tensor Inversion
NASA Astrophysics Data System (ADS)
Chao, W.; Zhao, L.; Wu, Y.
2009-12-01
The Chia-Yi area in southwestern Taiwan is a region of relatively high seismicity with frequent earthquakes of variable magnitudes in the shallow crust. These events provide valuable information for the understanding of seismotectonics of this region. In this study, we investigate the source properties of small to moderate earthquakes (3.0 < ML < 5.5) in the Chia-Yi region by inverting for their point as well as finite moment tensors. Finite moment tensor is a simplified representation of a finite source, and it can be used to resolve the fault-plane ambiguity of a point source model and determine the actual rupture plane of an earthquake. Based on a three-dimensional (3D) structural model for the Chia-Yi region, we compute the strain Green tensors by the finite-difference method. These strain Green tensors can be used to compute the synthetic seismograms as well as the partial derivatives for the inversion of point and finite moment tensor parameters. Frequency-dependent P-wave amplitude perturbations are measured from broadband and strong-motion seismograms and inverted for the point and finite moment tensors, which are then used to identify the actual rupture planes of earthquakes. With this approach, more details of small and moderate earthquakes, in particular their actual rupture fault planes, can be determined in realistic 3D structure, which helps us to understand the regional seismotectonics and the stress field. Keywords: Taiwan, Green function, finite moment tensors (FMTs).
Geometric plane shapes for computer-generated holographic engraving codes
NASA Astrophysics Data System (ADS)
Augier, Ángel G.; Rabal, Héctor; Sánchez, Raúl B.
2017-04-01
We report a new theoretical and experimental study on hologravures, as holographic computer-generated laser-engravings. A geometric theory of images based on the general principles of light ray behaviour is shown. The models used are also applicable for similar engravings obtained by any non-laser method, and the solutions allow for the analysis of particular situations, not only in the case of light reflection mode, but also in transmission mode geometry. This approach is a novel perspective allowing the three-dimensional (3D) design of engraved images for specific ends. We prove theoretically that plane curves of very general geometric shapes can be used to encode image information onto a two-dimensional (2D) engraving, showing notable influence on the behaviour of reconstructed images that appears as an exciting investigation topic, extending its applications. Several cases of code using particular curvilinear shapes are experimentally studied. The computer-generated objects are coded by using the chosen curve type, and engraved by a laser on a plane surface of suitable material. All images are recovered optically by adequate illumination. The pseudoscopic or orthoscopic character of these images is considered, and an appropriate interpretation is presented.
Theoretical calculation of plane wave speeds for alkali metals under pressure.
NASA Technical Reports Server (NTRS)
Eftis, J.; Macdonald, D. E.; Arkilic, G. M.
1971-01-01
Theoretical calculations of the variation with pressure of small amplitude plane wave speeds are performed for sodium and potassium at zero temperature. The results obtained for wave speeds associated with volume dependent second-order elastic coefficients show better agreement with experimental data than for wave speeds associated with shear dependent coefficients. This result is believed to be due to omission of the band structure correction to the strain energy density.
Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity
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
Principal Strain Vascular Elastography: Simulation and Preliminary Clinical Evaluation.
Nayak, Rohit; Huntzicker, Steven; Ohayon, Jacques; Carson, Nancy; Dogra, Vikram; Schifitto, Giovanni; Doyley, Marvin M
2017-03-01
It is difficult to produce reliable polar strain elastograms (radial and circumferential) because the center of the carotid artery is typically unknown. Principal strain imaging can overcome this limitation, but suboptimal lateral displacement estimates make this an impractical approach for visualizing mechanical properties within the carotid artery. We hypothesized that compounded plane wave imaging can minimize this problem. To test this hypothesis, we performed (i) simulations with vessels of varying morphology and mechanical behavior (i.e., isotropic and transversely isotropic), and (ii) a pilot study with 10 healthy volunteers. The accuracy of principal and polar strain (computed using knowledge of the precise vessel center) elastograms varied between 7% and 17%. In both types of elastograms, strain concentrated at the junction between the fibrous cap and the vessel wall, and the strain magnitude decreased with increasing fibrous cap thickness. Elastograms of healthy volunteers were consistent with those of transversely isotropic homogeneous vessels; they were spatially asymmetric, a trend that was common to both principal and polar strains. No significant differences were observed in the mean strain recovered from principal and polar strains (p > 0.05). This investigation indicates that principal strain elastograms measured with compounding plane wave imaging overcome the problems incurred when polar strain elastograms are computed with imprecise estimates of the vessel center. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
NASA Astrophysics Data System (ADS)
Cherifi, S.; Boeglin, C.; Stanescu, S.; Deville, J. P.; Mocuta, C.; Magnan, H.; Le Fèvre, P.; Ohresser, P.; Brookes, N. B.
2001-11-01
The effects of nanostructured magnetic Fe65Ni35 films deposited on a vicinal Cu(111) single-crystal surface on the magnetic anisotropy have been studied using magnetic circular x-ray dichroism (MCXD) at the Fe L2,3 edges. In the one-dimensional (1D) limit a large dipolar out-of-plane anisotropy is evidenced with in-plane isotropic magnetic moments. After the 1D coalescence the orbital moment shows a more complex behavior depending on the in-plane direction of saturation. We show that MCXD is strongly sensitive to in-plane orbital anisotropy for the 1D stripes. We demonstrate the importance of the step induced in-plane anisotropy by measuring the orbital magnetic moment dependence as a function of the in-plane azimuth angle. In the submonolayer regime an in-plane magnetic anisotropy is observed related to the step decoration growth mode. In the thickness range of 2-4 equivalent monolayers, 2D coalescence induces a strong in-plane magnetic anisotropy of the magnetic orbital moment. The microscopic origin of the strong in-plane variation of ML has been attributed to magnetocrystalline effects. Strained films give rise to an in-plane magnetic anisotropy energy up to 2 meV/at., which is larger than those measured out of the plane (0-1 meV/at.).