THE RIGIDITY OF THE EARTH'S INNER CORE
Directory of Open Access Journals (Sweden)
K. E. BULLEN
1953-06-01
Full Text Available The purpose of this paper is to examine and assess, in the
light of recent evidence, the theory lliat the Earth's inner core has
a significant rigidity.
The presenee of an inner core in the Earth is revealed from
observations of the seismie pliase PKP in the « sliadow zone » for
which the epicentral distance A lies in the range 105" < A < 143".
Miss I. Lehmann (r in 1936, followed by Gutenberg and Richter (2
in 1938, atlrihuted these observations to tlie presence of an inner
core; and Jeffreys (3 in 1939 applied Airy's theory of diffraetion
near a caustic to sliow that the alternative theory of diffraetion
round the outer boundary of the centrai core was not capable of
explaining tlie observations in the shadow zone. The existence of the
inner core has been fairly generallv accepted sinee tliis ealculation
of Jeffreys.
Hamiltonian theory for the non-rigid Earth: Semidiurnal terms
Getino, J.; Ferrándiz, J. M.; Escapa, A.
2001-04-01
The purpose of this paper is to determine the contributions to the nutation series arising from the triaxiality of a non-rigid Earth model composed of a rigid mantle and a liquid core. With this aim, the canonical formulation of the rotation of the non-rigid Earth developed by Getino and Ferrándiz is applied in order to study the semidiurnal terms arising from the C22 and S22 geopotential coefficients. Once the corresponding generating function is calculated, analytical expressions of the Andoyer and figure planes are derived. We also provide numerical nutation series based on the analytical formulae.
Theory of the rotation of the rigid earth
Kinoshita, H.
1977-01-01
Equations of motion for a triaxial rigid earth are derived in Andoyer variables. The reference plane is the ecliptic of date which is moving as a result of planetary perturbations. By using this noninertial system, the development of the disturbing function for the sun and moon is simplified, with an additional term appearing in the Hamiltonian which, however, contributes only to precessional motion. The nutation terms derived are compared with those of Woolard.
Aboumoussa, Walid
2014-01-01
Structures placed on hillsides often present a number of challenges and a limited number of economical choices for site design. An option sometimes employed is to use the building frame as a retaining element, comprising a Rigidly Framed Earth Retaining Structure (RFERS). The relationship between temperature and earth pressure acting on RFERS, is explored in this monograph through a 4.5 year monitoring program of a heavily instrumented in service structure. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also revealed that thermal cycles, rather than lateral earth pressure, were the cause of failure in many structural elements. The book demonstrates that depending on the relative stiffness of the retained soil mass and that of the structural frame, the developed lateral earth pressure, during thermal expansion, can reach magnitudes several times larger than those determined using classical earth pressure theories....
Geopotential of a triaxial Earth with a rigid inner core in Andoyer canonical variables
Escapa, A.; Getino, J.; Ferrándiz, J. M.
2008-04-01
We derive analytical expressions for the geopotential of a three-layer Earth model com- posed by a triaxial rigid mantle, a triaxial fluid outer core and a triaxial rigid inner core, extending previous works performed on the basis of an axial-symmetric three-layer Earth model (Greiner-Mai et al. 2000, 2001). In order to consider these expressions within the framework of the Hamiltonian theory of the rotation of the non-rigid Earth, we work out the problem in terms of a set of canonical variables arising from associating an Andoyer-like variables to each layer of the Earth, in the same way as it is described in Escapa et al.(2001). With the help of Wigner theorem (Kinoshita et al. 1974), we obtain the development of the geopotential of this Earth model in a mantle attached reference frame. Finally, we analyze the dependence of each geopotential coefficient of the second degree on the triaxiality and figure axis of the rigid inner core.
Getino, J.; Escapa, A.; Miguel, D.
2010-05-01
This paper is the first part of an investigation where we will present an analytical general theory of the rotation of the non-rigid Earth at the second order, which considers the effects of the interaction of the rotation of the Earth with itself, also named as the spin-spin coupling. Here, and as a necessary step in the development of that theory, we derive complete, explicit, analytical formulae of the rigid Earth rotation that account for the second-order rotation-rotation interaction. These expressions are not provided in this form by any current rigid Earth model. Working within the Hamiltonian framework established by Kinoshita, we study the second-order effects arising from the interaction of the main term in the Earth geopotential expansion with itself, and with the complementary term arising when referring the rotational motion to the moving ecliptic. To this aim, we apply a canonical perturbation method to solve analytically the canonical equations at the second order, determining the expressions that provide the nutation-precession, the polar motion, and the length of day. In the case of the motion of the equatorial plane, nutation-precession, we compare our general approach with the particular study for this motion developed by Souchay et al., showing the existence of new terms whose numerical values are within the truncation level of 0.1 μas adopted by those authors. These terms emerge as a consequence of not assuming in this work the same restrictive simplifications taken by Souchay et al. The importance of these additional contributions is that, as the analytical formulae show, they depend on the Earth model considered, in such a way that the fluid core resonance could amplify them significatively when extending this theory to the non-rigid Earth models.
Numerical analysis of the rigid Earth rotation with the quadruple precision
Eroshkin, G. I.; Pashkevich, V. V.; Brzeziński, A.
The present investigation is a development of the previous research on the rigid Earth rotation problem (Eroshkin et al., 2002). The problem is studied numerically by using a high-performance computer Parsytec CCe20. All the calculations are carried out with the quadrupole precision. Numerical integration of the differential equations is performed over the time interval of 2000 years, from AD 1000 to 3000, with the initial epoch January 1, 2000. The ephemerides DE404/LE404 (Standish et al., 1995) are used as a generator of the positions and velocities of the disturbing bodies. The problem is solved both for the Newtonian case (dynamical case) and for the relativistic one (kinematical case) in which the geodetic perturbations in the Earth rotation are taken into account. Over the whole time interval of the numerical integration the solutions are compared with the corresponding solutions of the semi-analytical theory SMART97 (Bretagnon et al., 1998), corrected previously in accordance with the reuslts of (Brumberg and Bretagnon, 2000).
Application of the spectral analysis for the mathematical modelling of the rigid Earth rotation
Pashkevich, V. V.; Eroshkin, G. I.
The new semi-analytical series - S9000 - describing the high-precision rigid Earth rotation, dynamically adequate to the ephemerides DE404/LE404 over 2000 year time interval, are constructed. The series S9000 are obtained by processing the discrepancies of the comparison between the quadruple precision numerical solutions of the problem and the semi-analytical ones - SMART97 solutions - (Bretagnon et al., 1998), (Brumberg and Bretagnon, 2000) by means of the spectral analysis methods. The comparison between the quadruple precision numerical solutions of the problem and S9000 series reveals the discrepancies less than 10μas over 2000 year time interval. The residuals of the comparison between S9000 series and the high-precision numerical integration are processed for the determination of the diurnal and sub-diurnal harmonics. The addition of the short-period terms to S9000 are constructed over 200 year time interval for the Kinematical case. The comparison between the quadruple precision numerical solutions of the problem and S9000 series with short-periodical part reveals the discrepancies less than 1.2μas over 200 year time interval.
The Effect of Displacement Mode of Rigid Retaining Walls on Shearing Bands by Active Earth Pressure
Directory of Open Access Journals (Sweden)
A. Sekkel
2013-10-01
Full Text Available This work treats the physical modeling of failure mechanisms by active earth pressure. This last is developed by retaining wall movement. A lot of research showed that wall displacement has a significant effect on active earth pressure. A good comprehension of active earth pressure phenomenon and its failure mechanisms help us to better conceive retaining walls. The conception of a small-scale model allowed the realization of active earth pressure tests, while displacing the mobile wall toward the outside of the massif. The studied material is that of Schneebeli; light two-dimensional material made of cylindrical plastic rollers, simulating granular non-cohesive soil. The evolution of shearing zones under continuous and discontinuous displacement modes of mobile walls by correlation pictures allows the investigation of the localization of deformations and failure mechanisms.
Carter, Jason
2017-01-01
This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp
Elasticity of Relativistic Rigid Bodies?
Smarandache, Florentin
2013-10-01
In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.
Directory of Open Access Journals (Sweden)
Steven J. Gortler
2013-12-01
Full Text Available We study the properties of affine rigidity of a hypergraph and prove a variety of fundamental results. First, we show that affine rigidity is a generic property (i.e., depends only on the hypergraph, not the particular embedding. Then we prove that a graph is generically neighborhood affinely rigid in d-dimensional space if it is (d+1-vertex-connected. We also show neighborhood affine rigidity of a graph implies universal rigidity of its squared graph. Our results, and affine rigidity more generally, have natural applications in point registration and localization, as well as connections to manifold learning.
Rigid particulate matter sensor
Hall, Matthew [Austin, TX
2011-02-22
A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.
Influence of rigid boundary on the propagation of torsional surface ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Earth System Science; Volume 124; Issue 1. Influence of rigid boundary on the propagation of torsional ... rigid boundary, whereas it does at the free boundary. Graphical user interface (GUI) software has been developed using MATLAB 7.5 to generalize the effect of various parameter discussed.
Weiss, Asia; Whiteley, Walter
2014-01-01
This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme. Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology. The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...
Energy Technology Data Exchange (ETDEWEB)
Steckle, W.P. Jr. [Los Alamos National Lab., NM (United States); Mitchell, M.A. [Chemidal Corp., Palatine, IL (United States); Aspen, P.G. [Simula Inc., Phoenix, AZ (United States)
1998-12-31
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability, and processing. Rigid molecular foams or {open_quotes}organic zeolites{close_quotes} would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with dichloroxylene (DCX) as the pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15 g/cc to 0.75 g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and the crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6 {angstrom} to 2,000 {angstrom}.
Gasch, Matthew J.
2011-01-01
NASA Exploration Systems Mission Directorate s (ESMD) Entry, Descent, and Landing (EDL) Technology Development Project (TDP) and the NASA Aeronautics Research Mission Directorate s (ARMD) Hypersonics Project are developing new advanced rigid ablators in an effort to substantially increase reliability, decrease mass, and reduce life cycle cost of rigid aeroshell-based entry systems for multiple missions. Advanced Rigid Ablators combine ablation resistant top layers capable of high heat flux entry and enable high-speed EDL with insulating mass-efficient bottom that, insulate the structure and lower the areal weight. These materials may benefit Commercial Orbital Transportation Services (COTS) vendors and may potentially enable new NASA missions for higher velocity returns (e.g. asteroid, Mars). The materials have been thermally tested to 400-450 W/sq cm at the Laser Hardened Materials Evaluation Lab (LHMEL), Hypersonics Materials Evaluation Test System (HyMETS) and in arcjet facilities. Tested materials exhibit much lower backface temperatures and reduced recession over the baseline materials (PICA). Although the EDL project is ending in FY11, NASA in-house development of advanced ablators will continue with a focus on varying resin systems and fiber/resin interactions.
DEFF Research Database (Denmark)
Niebe, Sarah Maria
The topic of this thesis is the numerics of rigid body simulation, with focus on the contact force problem. Three contact force models are presented, followed by three contact point determination methods. To solve the contact force problem, six different numerical methods are presented, each......-Seidel (PGS), although computationally more expensive. The NNCG method has been implemented in the physics library Bullet, as of revision r2709, as an alternative to the PGS method. A subspace minimization method is developed to improve convergence of the PGS method, improving the results of large mass ratio...
Rigid Motion and Adapted Frames
Lyle, Stephen N.
The aim here is to describe the rigid motion of a continuous medium in special and general relativity. Section 7.1 defines a rigid rod in special relativity, and Sect. 7.2 shows the link with the space coordinates of a certain kind of accelerating frame in flat spacetimes. Section 7.3 then sets up a notation for describing the arbitrary smooth motion of a continuous medium in general curved spacetimes, defining the proper metric of such a medium. Section 7.4 singles out rigid motions and shows that the rod in Sect. 7.1 undergoes rigid motion in the more generally defined sense. Section 7.5 defines a rate of strain tensor for a continuous medium in general relativity and reformulates the rigidity criterion. Section 7.6 aims to classify all possible rigid motions in special relativity, reemphasizing the link with semi-Euclidean frames adapted to accelerating observers in special relativity. Then, Sects. 7.7 and 7.8 describe rigid motion without rotation and rigid rotation, respectively. Along the way we introduce the notion of Fermi-Walker transport and discuss its relevance for rigid motions. Section 7.9 brings together all the above themes in an account of a recent generalization of the notion of uniform acceleration, thereby characterizing a wide class of rigid motions.
Torsional Rigidity of Minimal Submanifolds
DEFF Research Database (Denmark)
Markvorsen, Steen; Palmer, Vicente
2006-01-01
We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...... for the torsional rigidity are actually attained and give conditions under which the geometric average of the stochastic mean exit time for Brownian motion at infinity is finite....
Energy Technology Data Exchange (ETDEWEB)
Park, Sora; Ahn, Jeung Sun; Kwon, Young-Kyun; Tomanek, David [Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul, 130-701 (Korea, Republic of); Kittimanapun, Kritsada, E-mail: ykkwon@khu.ac.k, E-mail: tomanek@pa.msu.ed [Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824-2320 (United States)
2010-08-25
We use ab initio density functional calculations to study the stability, elastic properties and electronic structure of sp{sup 2} carbon minimal surfaces with negative Gaussian curvature, called schwarzites. We focus on two systems with cubic unit cells containing 152 and 200 carbon atoms, which are metallic and very rigid. The porous schwarzite structure allows for efficient and reversible doping by electron donors and acceptors, making it a promising candidate for the next generation of alkali ion batteries. We identify schwarzite structures that act as arrays of interconnected spin quantum dots or become magnetic when doped. We introduce two interpenetrating schwarzite structures that may find their use as the ultimate super-capacitor.
DEFF Research Database (Denmark)
Troiano, Giovanni Maria
Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape...... sensors in the five preferred objects and programmed them for controlling sounds with computer software. Finally, we ran a performance study where six musicians performed music with deformable interfaces at their studios. Results from the performance study show that musicians systematically map......, Transformation, Adaptation and Physicalization. In synthesis, the work presented in this thesis shows (1) implications of usefulness for deformable interfaces and how their new input modalities can redefine the way users interact with computers, and (2) how a systematic understanding of conventional design...
Understanding geological processes: Visualization of rigid and non-rigid transformations
Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.
2012-12-01
Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid
Quantum charged rigid membrane
Energy Technology Data Exchange (ETDEWEB)
Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)
2011-03-21
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
The structure of rigid functions
Balka, Richárd; Elekes, Márton
2008-09-01
A function is called vertically rigid if graph(cf) is isometric to graph(f) for all c[not equal to]0. We prove Jankovic's conjecture by showing that a continuous function is vertically rigid if and only if it is of the form a+bx or a+bekx (). We answer the question of Cain, Clark and Rose by showing that there exists a Borel measurable vertically rigid function which is not of the above form. We discuss the Lebesgue and Baire measurable case, consider functions bounded on some interval and functions with at least one point of continuity. We also introduce horizontally rigid functions, and show that a certain structure theorem can be proved without assuming any regularity.
Reference Frames and Rigid Motions in Relativity: Applications
Soler, D.
2006-11-01
The concept of rigid reference frame and of constricted spatial metric, given in the previous work [\\emph{Class. Quantum Grav.} {\\bf 21}, 3067,(2004)] are here applied to some specific space-times: In particular, the rigid rotating disc with constant angular velocity in Minkowski space-time is analyzed, a new approach to the Ehrenfest paradox is given as well as a new explanation of the Sagnac effect. Finally the anisotropy of the speed of light and its measurable consequences in a reference frame co-moving with the Earth are discussed.
Rigid therapies, rigid minds: italian professionals' perspectives on autism interventions.
Cascio, M Ariel
2015-06-01
Many therapies, interventions, and programs seek to improve outcomes and quality of life for people diagnosed with autism spectrum conditions. This paper addresses Italian professionals' perspectives on a variety of such interventions, including TEACCH, ABA, Defeat Autism Now!, and Doman-Delacato. Drawing on participant-observation and interviews collected in 2012-2013 in a northern region of Italy, it highlights the theme of "rigidity" that appears in professionals' discourses about both the characteristics of people with autism and the potential risks of adhering too strictly to any particular treatment protocol. The co-occurrence of the theme of rigidity across different domains demonstrates a way in which diagnostic characteristics become metaphors for medical practice. This paper proposes that such discursive moves may help bridge the gap between people with autism and people who work with them because a key attribute of people with autism-thinking and/or acting rigidly-is also a potential pitfall for people without autism.
The dynamical rigid body with memory
Albu, Ion Doru; Neamtu, Mihaela; Opris, Dumitru
2007-01-01
In the present paper we describe the dynamics of the revised rigid body, the dynamics of the rigid body with distributed delays and the dynamics of the fractional rigid body. We analyze the stationary states for given values of the rigid body's parameters.
Rigidly foldable origami gadgets and tessellations.
Evans, Thomas A; Lang, Robert J; Magleby, Spencer P; Howell, Larry L
2015-09-01
Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented.
DEFF Research Database (Denmark)
Rijkhoff, Jan
2010-01-01
This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...... classes. Finally this article wants to claim that the distinction between rigid and flexible noun categories (a) adds a new dimension to current classifications of parts of speech systems, (b) correlates with certain grammatical phenomena (e.g. so-called number discord), and (c) helps to explain the parts...
On general Earth's rotation theory
Brumberg, V.; Ivanova, T.
2009-09-01
This paper dealing with the general problem of the rigid-body rotation of the three-axial Earth represents a straightforward extension of (Brumberg and Ivanova, 2007) where the simplified Poisson equations of rotation of the axially symmetrical Earth have been considered. The aim of the present paper is to reduce the equations of the translatory motion of the major planets and the Moon and the equations of the Earth's rotation around its centre of mass to the secular system describing the evolution of the planetary and lunar orbits (independent of the Earth's rotation) and the evolution of the Earth's rotation (depending on the planetary and lunar evolution).
Theoretical aspects of the Earth rotation.
Kinoshita, H.; Sasao, T.
Contents: 1. Basic equations and Woolard's theory of a rigid Earth. 2. Description of a rotational motion with use of Andoyer variables. 3. Disturbing potential and the Hamiltonian referred to a moving plane. 4. Nutation and precession. 5. Effects of non-rigidity: Tisserand mean system; general formulation of the problem; Molodensky's approach; theory of Wahr; recent observations and their implications.
Accurate free and forced rotational motions of rigid Venus
Cottereau, L.; Souchay, J.; Aljbaae, S.
2010-06-01
Context. The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting because it can be compared with that of Earth for which such a modelling has already been achieved at the milli-arcsecond level. Aims: We aim to complete a previous study, by determining the polhody at the milli-arcsecond level, i.e. the torque-free motion of the angular momentum axis of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view. Methods: We use the same theoretical framework as Kinoshita (1977, Celest. Mech., 15, 277) did to determine the precession-nutation motion of a rigid Earth. It is based on a representation of the rotation of a rigid Venus, with the help of Andoyer variables and a set of canonical equations in Hamiltonian formalism. Results: In a first part we computed the polhody, we showed that this motion is highly elliptical, with a very long period of 525 cy compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we precisely computed the Oppolzer terms, which allow us to represent the motion in space of the third Venus figure axis with respect to the Venus angular momentum axis under the influence of the solar gravitational torque. We determined the corresponding tables of the nutation coefficients of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We showed that the nutation coefficients for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration, which revealed the indirect planetary effects.
Rigid body dynamics of mechanisms
Hahn, Hubert
2003-01-01
The second volume of Rigid Body Dynamics of Mechanisms covers applications via a systematic method for deriving model equations of planar and spatial mechanisms. The necessary theoretical foundations have been laid in the first volume that introduces the theoretical mechanical aspects of mechatronic systems. Here the focus is on the application of the modeling methodology to various examples of rigid-body mechanisms, simple planar ones as well as more challenging spatial problems. A rich variety of joint models, active constraints, plus active and passive force elements is treated. The book is intended for self-study by working engineers and students concerned with the control of mechanical systems, i.e. robotics, mechatronics, vehicles, and machine tools. The examples included are a likely source from which to choose models for university lectures.
DEFF Research Database (Denmark)
Rijkhoff, Jan
2008-01-01
Studies in Language 32-3 (2008), 727-752. Special issue: Parts of Speech: Descriptive tools, theoretical constructs Jan Rijkhoff - On flexible and rigid nouns This article argues that in addition to the flexible lexical categories in Hengeveld’s classification of parts-of-speech systems (Contentive...... classifications of parts-of-speech systems, (b) correlates with certain grammatical phenomena (e.g. so called number discord), and (c) helps to explain the parts-of-speech hierarchy....
Rigidizing Inflatable Deployable Dwelling (RIDD) Project
National Aeronautics and Space Administration — By combining thin thermoplastic films, woven Vectran reinforcements, and heat a reliable, deployable, rigidizing space habitat can be created. Although much research...
Rigidity in Mentally Retarded and Nonretarded Children.
Kreitler, Shulamith; And Others
1990-01-01
Seven rigidity tests varying in difficulty were administered to 45 retarded subjects, with a mean age of 10, and 45 mental age-matched nonretarded subjects. Subjects did not differ on 3 easy tests, but retarded children were more rigid on 4 difficult tests. (Author/JDD)
Static elastic deformation in an orthotropic half-space with rigid ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Earth System Science; Volume 126; Issue 7. Static elastic deformation in an orthotropic half-space with rigid boundary model due to non-uniform long strike slip fault. Yogita Godara Ravinder Kumar Sahrawat Mahabir Singh. Volume 126 Issue 7 October 2017 Article ID 97 ...
Semiclassical Theory of Spectral Rigidity
Berry, M. V.
1985-08-01
The spectral rigidity Δ(L) of a set of quantal energy levels is the mean square deviation of the spectral staircase from the straight line that best fits it over a range of L mean level spacings. In the semiclassical limit (hslash-> 0), formulae are obtained giving Δ(L) as a sum over classical periodic orbits. When L ~= Lmax, where Lmax ~ hslash-(N-1) for a system of N freedoms, Δ(L) is shown to display the following universal behaviour as a result of properties of very long classical orbits: if the system is classically integrable (all periodic orbits filling tori), Δ(L) = 1/15L (as in an uncorrelated (Poisson) eigenvalue sequence); if the system is classically chaotic (all periodic orbits isolated and unstable) and has no symmetry, Δ(L) = ln L/2π^2 + D if 1 ~= L ~= Lmax (as in the gaussian unitary ensemble of random-matrix theory); if the system is chaotic and has time-reversal symmetry, Δ(L) = ln L/π^2 + E if 1 ~= L ~= Lmax (as in the gaussian orthogonal ensemble). When L >> Lmax, Δ(L) saturates non-universally at a value, determined by short classical orbits, of order hslash-(N-1) for integrable systems and ln (hslash-1) for chaotic systems. These results are obtained by using the periodic-orbit expansion for the spectral density, together with classical sum rules for the intensities of long orbits and a semiclassical sum rule restricting the manner in which their contributions interfere. For two examples Δ(L) is studied in detail: the rectangular billiard (integrable), and the Riemann zeta function (assuming its zeros to be the eigenvalues of an unknown quantum system whose unknown classical limit is chaotic).
Inertial rotation of a rigid body
Butikov, Eugene
2006-07-01
A simple approach to the important problem of torque-free rotation of a symmetrical rigid body is suggested which is appropriate for teaching introductory mechanics and general physics to undergraduate students and is free from the difficulties of traditional treatment of the problem. A small simulation program (Java-applet) is developed that visualizes the investigated motion and illustrates its principal features. The program facilitates understanding of concepts behind rigid body dynamics. Simultaneously with simulating the rigid body motion, the program presents a clear geometrical interpretation of the inertial rotation.
Analysis of Switched-Rigid Floating Oscillator
Directory of Open Access Journals (Sweden)
Prabhakar R. Marur
2009-01-01
Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.
Rigid bronchoscope dilatation of postintubation tracheal stenosis
African Journals Online (AJOL)
The management modalities that have been employed for the management of. PITS include stenting, surgical resection and reconstruction, percutaneous dilatation, rigid bronchoscopic dilatation, fibreoptic assisted balloon dilatation and Nd: YAG. (neodyiniumrvttritiurn-aluniinuni garnet) laser therapy with or without stenting.
An Immersed Boundary Method for Rigid Bodies
Bhalla, Amneet Pal Singh; Kallemov, Bakytzhan; Donev, Aleksandar; Griffith, Boyce
2014-11-01
The traditional immersed boundary (IB) method is a very flexible method for coupling elastic structures to fluid flow. When rigid bodies are modeled using an IB approach, a penalty method is usually employed to approximately enforce the rigidity of the body; this requires small time step sizes and leads to difficult-to-control errors in the solution. We develop a method that exactly enforces a rigidity constraint by solving a linear system coupling a standard semi-implicit discretization of the fluid equations with a rigidity constraint. We develop a preconditioned iterative solver that combines an approximate multigrid solver for the fluid problem with an approximate direct solver for the Schur complement system. We demonstrate the efficiency and study the accuracy of the method on several test problems for both zero and finite Reynolds numbers.
Consumers' Imperfect Information and Price Rigidities
Jean-Paul L'Huillier
2012-01-01
This paper develops a model of price rigidities and information diffusion in decentralized markets with private information. First, I provide a strategic microfoundation for price rigidities, by showing that firms are better off delaying the adjustment of prices when they face a high number of uninformed consumers. Second, in an environment where consumers learn from firms' prices, the diffusion of information follows a Bernoulli differential equation. Therefore, learning follows nonlinear dy...
Interband B (E2) ratios in the rigid triaxial model, a review
Energy Technology Data Exchange (ETDEWEB)
Gupta, J.B.; Sharma, S.
1989-01-01
Uptodate accurate extensive data on /gamma/-g B(E2) ratios for even-even rare-earth nuclei is compared with the predictions of the rigid triaxial model of collective rotation to search for a correlation between the nuclear structure variation with Z, N and the /gamma//sub 0/ parameter of the model. The internal consistency in the predictions of the model is investigated and the spectral features vis-a-vis the /gamma/-soft and the /gamma/-rigid potential are discussed. (orig.).
Metrology of Non-Rigid Objects
Energy Technology Data Exchange (ETDEWEB)
Blaedel, K L; Smith, D W; Claudet, A A; Kasper, E P; Patterson, S R
2002-01-01
Dimensional characterization of non-rigid parts presents many challenges. For example, when a non-rigid part is mounted in an inspection apparatus the effects of fixturing constraints cause significant deformation of the part. If the part is not used in normal service with the same load conditions as during inspection, the dimensional characteristics in service will deviate from the reported values during inspection. Further, the solution of designing specialized fixturing to duplicate ''as-installed'' conditions does not fully resolve the problem because each inspection requires its own methodology. The goal of this project is to formulate the research problem and propose a method of assessing the dimensional characteristics of non-rigid parts. The measured dimension of a rigid component is traceable at some level of confidence to a single source (NIST in the USA). Hence the measurement of one component of an assembly can be related to the measurement of another component of that assembly. There is no generalized analog to this pedigreed process for dimensionally characterizing non-rigid bodies. For example, a measurement made on a sheet-metal automobile fender is heavily influenced by how it is held during the measurement making it difficult to determine how well that fender will assemble to the rest of the (non-rigid) car body. This problem is often overcome for specific manufacturing problems by constructing rigid fixtures that over-constrain the non-rigid parts to be assembled and then performing the dimensional measurement of the contour of each component to check whether each meets specification. Note that such inspection measurements will yield only an approximation to the assembled shape, which is a function of both the geometry and the compliance of the component parts of the assembly. As a result, non-rigid components are more difficult to specify and inspect and therefore are more difficult to purchase from outside vendors compared
Metrology of Non-Rigid Objects
Energy Technology Data Exchange (ETDEWEB)
Blaedel, K; Swift, D; Claudet, A; Kasper, E; Patterson, S
2002-01-01
Dimensional characterization of non-rigid parts presents many challenges. For example, when a non-rigid part is mounted in an inspection apparatus the effects of fixturing constraints are significant. If the part is not used in normal service with the same load conditions as during inspection, the dimensional characteristics will deviate from reported values. Further, the solution of designing specialized fixturing to duplicate ''as-installed'' conditions does not fully resolve the problem because each inspection requires its own methodology. The goal of this project is to formulate the research problem and propose a method of assessing the dimensional characteristics of non-rigid parts. The measured dimension of a rigid component is traceable at some level of confidence to a single source (NIST in the USA). Hence the measurement of one component of an assembly can be related to the measurement of another component of that assembly. There is no generalized analog to this pedigreed process for dimensionally characterizing non-rigid bodies. For example, a measurement made on a sheet-metal automobile fender is heavily influenced by how it is held during the measurement making it difficult to determine how well that fender will assemble to the rest of the (non-rigid) car body. This problem is often overcome for specific manufacturing problems by constructing rigid fixtures that over-constrain the non-rigid parts to be assembled and then performing the dimensional measurement of the contour of each component to check whether each meets specification. Note that such inspection measurements will yield only an approximation to the assembled shape, which is a function of both the geometry and the compliance of the component parts of the assembly. As a result, non-rigid components are more difficult to specify and inspect and therefore are more difficult to purchase from outside vendors compared to rigid components. The problems are compounded as the
21 CFR 876.3630 - Penile rigidity implant.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in the...
Algorithms for Graph Rigidity and Scene Analysis
DEFF Research Database (Denmark)
Berg, Alex Rune; Jordán, Tibor
2003-01-01
We investigate algorithmic questions and structural problems concerning graph families defined by `edge-counts'. Motivated by recent developments in the unique realization problem of graphs, we give an efficient algorithm to compute the rigid, redundantly rigid, M-connected, and globally rigid...... components of a graph. Our algorithm is based on (and also extends and simplifies) the idea of Hendrickson and Jacobs, as it uses orientations as the main algorithmic tool. We also consider families of bipartite graphs which occur in parallel drawings and scene analysis. We verify a conjecture of Whiteley...... by showing that 2d-connected bipartite graphs are d-tight. We give a new algorithm for finding a maximal d-sharp subgraph. We also answer a question of Imai and show that finding a maximum size d-sharp subgraph is NP-hard....
Measuring the Acceleration of a Rigid Body
Directory of Open Access Journals (Sweden)
Peter G. Martin
1998-01-01
Full Text Available Two methods to measure the six-degree-of-freedom acceleration of a point on a rigid body are presented. The first, referred to as the periphery scheme, makes use of three clusters of accelerometers mounted orthogonal to each other and coincident with the axes of the point. One of the clusters consists of the three accelerometers attached to a cube-shaped triaxial angular rate sensor (ARS. The second method, called the compact cube scheme, uses a single 3-accelerometer/ARS cluster that may be mounted anywhere on the rigid body. During impact tests with an instrumented rigid body, both methods produced measurements that were highly correlated near the time of peak acceleration. Whereas the compact cube scheme was more economical and easier to implement, the periphery scheme produced results that were less disrupted by instrument signal errors and noisy environments.
Torsional rigidity of submanifolds with controlled geometry
DEFF Research Database (Denmark)
Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente
2009-01-01
We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds ^m$ with controlled radial mean curvature in ambient Riemannian manifolds ^n$ with a pole $ and with sectional curvatures bounded from above and from below, respectively. These bounds are given...... in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped product model spaces. Our main results are obtained using methods from previously established isoperimetric inequalities, as found in e.g. [MP4] and [MP5]. As in [MP4] we also characterize the geometry...... of those situations in which the bounds for the torsional rigidity are actually attained and study the behavior at infinity of the so-called geometric average of the mean exit time for Brownian motion....
Quantum mechanics of a generalised rigid body
Gripaios, Ben; Sutherland, Dave
2016-05-01
We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid.
On Saturnian cosmic ray cutoff rigidities
Sauer, H. H.
1980-03-01
It has been determined that Saturn possesses a relatively pure dipolar magnetic field through magnetometer measurements made by Ness et al. (1979, private comm.) and Smith et al. (1979). The paper briefly outlines the dipole geomagnetic cutoff theory and demonstrates the scaling required for its applicability to energetic particle measurements in the vicinity of Saturn. Since the cutoff rigidity is a function of viewing direction, the effective cutoff rigidity must be determined as an integration over the finite viewing angle of a physical detector.
Evaluating a method for automated rigid registration
DEFF Research Database (Denmark)
Darkner, Sune; Vester-Christensen, Martin; Larsen, Rasmus
2007-01-01
, the influence of different norms and sampling point densities is evaluated. The performance of the two methods has been evaluated on data consisting of 178 scanned ear impressions taken from the right ear. To quantify the difference of the two methods we calculate the registration cost and the mean point......We evaluate a novel method for fully automated rigid registration of 2D manifolds in 3D space based on distance maps, the Gibbs sampler and Iterated Conditional Modes (ICM). The method is tested against the ICP considered as the gold standard for automated rigid registration. Furthermore...
Rigid origami vertices: conditions and forcing sets
Directory of Open Access Journals (Sweden)
Zachary Abel
2016-04-01
Full Text Available We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly. We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case. We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.
Rigidity analysis of HIV-1 protease
Heal, J. W.; Wells, S. A.; Jimenez-Roldan, E.; Freedman, R. F.; Römer, R. A.
2011-03-01
We present a rigidity analysis on a large number of X-ray crystal structures of the enzyme HIV-1 protease using the 'pebble game' algorithm of the software FIRST. We find that although the rigidity profile remains similar across a comprehensive set of high resolution structures, the profile changes significantly in the presence of an inhibitor. Our study shows that the action of the inhibitors is to restrict the flexibility of the β-hairpin flaps which allow access to the active site. The results are discussed in the context of full molecular dynamics simulations as well as data from NMR experiments.
The 'twin paradox' in relativistic rigid motion
Ben-Ya'acov, Uri
2017-01-01
Relativistic rigid motion suggests a new version for the so-called `twin paradox', comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being rigid, is simultaneously at rest, the twins' ages, measured as the proper-times along their individual world lines, are different when they are located at remote parts of the spaceship. The age, or proper-time, difference depends on the distance at rest betw...
Rigid polyurethane and kenaf core composite foams
Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...
Settling dynamics of asymmetric rigid fibers
E.J. Tozzi; C Tim Scott; David Vahey; D.J. Klingenberg
2011-01-01
The three-dimensional motion of asymmetric rigid fibers settling under gravity in a quiescent fluid was experimentally measured using a pair of cameras located on a movable platform. The particle motion typically consisted of an initial transient after which the particle approached a steady rate of rotation about an axis parallel to the acceleration of gravity, with...
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-05
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Secondary structure and rigidity in model proteins.
Perticaroli, Stefania; Nickels, Jonathan D; Ehlers, Georg; O'Neill, Hugh; Zhang, Qui; Sokolov, Alexei P
2013-10-28
There is tremendous interest in understanding the role that secondary structure plays in the rigidity and dynamics of proteins. In this work we analyze nanomechanical properties of proteins chosen to represent different secondary structures: α-helices (myoglobin and bovine serum albumin), β-barrels (green fluorescent protein), and α + β + loop structures (lysozyme). Our experimental results show that in these model proteins, the β motif is a stiffer structural unit than the α-helix in both dry and hydrated states. This difference appears not only in the rigidity of the protein, but also in the amplitude of fast picosecond fluctuations. Moreover, we show that for these examples the secondary structure correlates with the temperature- and hydration-induced changes in the protein dynamics and rigidity. Analysis also suggests a connection between the length of the secondary structure (α-helices) and the low-frequency vibrational mode, the so-called boson peak. The presented results suggest an intimate connection of dynamics and rigidity with the protein secondary structure.
Analysis and Modeling of Rigid Microswimmers
Meshkati, Farshad
In this thesis, we investigate magnetically actuated rigid microswimmers based on analytical and numerical schemes. These swimming micro-robots have medical applications such as drug delivery and in vivo diagnostics. Our model employs the method of regularized Stokeslets to faithfully incorporate the low-Reynolds-number hydrodynamics of arbitrary rigid geometries. We show how these magnetized swimmers can be actuated and controlled by externally rotating uniform magnetic fields. Our model predicts the swimming characteristics such as speed and direction. We show how to determine the dynamic stability of steadily rotating microswimmers. First, we address what is the simplest geometry capable of swimming. We illustrate that, despite the common belief that rigid microswimmers need to be chiral to be able to cause propulsion, a simple achiral 3-bead geometry can exhibit appreciable propulsion and controllability. We generalize this to explain the minimum geometric requirements for rigid rotating propulsion based on a symmetry analysis. Next, we investigate the implications of the stability analysis on the control of the 3-bead swimmer. We show that by adjusting the angle between the magnetic field and its rotation, one can control the existence of multiple stable rotation modes, leading to control of swimming direction and speed.
On the combinatorics of infinitesimally rigid frameworks
Laman, G.
2000-01-01
Starting from a short survey of minimal infinitesimally rigid frameworks it is shown by an example that and why a two-dimensional characterization of them cannot be extended to higher dimensions just like that. The findings of a closer inspection of the interdependence of the rows of the relevant
A relativistic generalisation of rigid motions
Llosa, J.; Molina, A.; Soler, D.
2012-07-01
A weaker substitute for the too restrictive class of Born-rigid motions is proposed, which we call radar-holonomic motions. The definition is expressed as a set of differential equations. Integrability conditions and Cauchy problem are studied. We finally obtain an example of a radar-holonomic congruence containing a given worldline with a given value of the rotation on this line.
Reference frames and rigid motions in relativity
Llosa, J.; Soler, D.
2004-07-01
A reference frame consists of a reference space, a time scale and a spatial metric. The geometric structure induced by these objects in spacetime is developed. The existence of a class of spatial metrics which are rigid, have free mobility and can be derived as a slight deformation of the radar metric, is demonstrated.
Cracking of open traffic rigid pavement
Directory of Open Access Journals (Sweden)
Niken Chatarina
2017-01-01
Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.
The two-body problem of a pseudo-rigid body and a rigid sphere
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Vereshchagin, M.; Gózdziewski, K.
2012-01-01
n this paper we consider the two-body problem of a spherical pseudo-rigid body and a rigid sphere. Due to the rotational and "re-labelling" symmetries, the system is shown to possess conservation of angular momentum and circulation. We follow a reduction procedure similar to that undertaken...... in the study of the two-body problem of a rigid body and a sphere so that the computed reduced non-canonical Hamiltonian takes a similar form. We then consider relative equilibria and show that the notions of locally central and planar equilibria coincide. Finally, we show that Riemann's theorem on pseudo...
Rigid Spine Syndrome among Children in Oman
Directory of Open Access Journals (Sweden)
Roshan Koul
2015-08-01
Full Text Available Objectives: Rigidity of the spine is common in adults but is rarely observed in children. The aim of this study was to report on rigid spine syndrome (RSS among children in Oman. Methods: Data on children diagnosed with RSS were collected consecutively at presentation between 1996 and 2014 at the Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A diagnosis of RSS was based on the patient’s history, clinical examination, biochemical investigations, electrophysiological findings, neuro-imaging and muscle biopsy. Atrophy of the paraspinal muscles, particularly the erector spinae, was the diagnostic feature; this was noted using magnetic resonance imaging of the spine. Children with disease onset in the paraspinal muscles were labelled as having primary RSS or rigid spinal muscular dystrophy. Secondary RSS was classified as RSS due to the late involvement of other muscle diseases. Results: Over the 18-year period, 12 children were included in the study, with a maleto- female ratio of 9:3. A total of 10 children were found to have primary RSS or rigid spinal muscular dystrophy syndrome while two had secondary RSS. Onset of the disease ranged from birth to 18 months of age. A family history was noted, with two siblings from one family and three siblings from another (n = 5. On examination, children with primary RSS had typical features of severe spine rigidity at onset, with the rest of the neurological examination being normal. Conclusion: RSS is a rare disease with only 12 reported cases found at SQUH during the study period. Cases of primary RSS should be differentiated from the secondary type.
Rigid cohomology over Laurent series fields
Lazda, Christopher
2016-01-01
In this monograph, the authors develop a new theory of p-adic cohomology for varieties over Laurent series fields in positive characteristic, based on Berthelot's theory of rigid cohomology. Many major fundamental properties of these cohomology groups are proven, such as finite dimensionality and cohomological descent, as well as interpretations in terms of Monsky-Washnitzer cohomology and Le Stum's overconvergent site. Applications of this new theory to arithmetic questions, such as l-independence and the weight monodromy conjecture, are also discussed. The construction of these cohomology groups, analogous to the Galois representations associated to varieties over local fields in mixed characteristic, fills a major gap in the study of arithmetic cohomology theories over function fields. By extending the scope of existing methods, the results presented here also serve as a first step towards a more general theory of p-adic cohomology over non-perfect ground fields. Rigid Cohomology over Laurent Series Fields...
Financial Constraints and Nominal Price Rigidities
DEFF Research Database (Denmark)
Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay
This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...
Lectures on formal and rigid geometry
Bosch, Siegfried
2014-01-01
A first version of this work appeared in 2005 as a Preprint of the Collaborative Research Center "Geometrical Structures in Mathematics" at the University of Münster. Its aim was to offer a concise and self-contained 'lecture-style' introduction to the theory of classical rigid geometry established by John Tate, together with the formal algebraic geometry approach launched by Michel Raynaud. These Lectures are now viewed commonly as an ideal means of learning advanced rigid geometry, regardless of the reader's level of background. Despite its parsimonious style, the presentation illustrates a number of key facts even more extensively than any other previous work. This Lecture Notes Volume is a revised and slightly expanded version of the original preprint and has been published at the suggestion of several experts in the field.
Rigidity of the magic pentagram game
Kalev, Amir; Miller, Carl A.
2017-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
Rigidity of the magic pentagram game
Kalev, Amir; Miller, Carl A.
2018-01-01
A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.
Rigid aleph_epsilon-saturated models of superstable theories
Shami, Ziv; Shelah, Saharon
1999-01-01
In a countable superstable NDOP theory, the existence of a rigid aleph_epsilon-saturated model implies the existence of 2^lambda rigid aleph_epsilon-saturated models of power lambda for every lambda>2^{aleph_0}.
Rank rigidity for CAT(0) cube complexes
Caprace, Pierre-Emmanuel; Sageev, Michah
2010-01-01
We prove that any group acting essentially without a fixed point at infinity on an irreducible finite-dimensional CAT(0) cube complex contains a rank one isometry. This implies that the Rank Rigidity Conjecture holds for CAT(0) cube complexes. We derive a number of other consequences for CAT(0) cube complexes, including a purely geometric proof of the Tits Alternative, an existence result for regular elements in (possibly non-uniform) lattices acting on cube complexes, and a characterization ...
Balancing of Rigid and Flexible Rotors
1986-01-01
IA14 nf~VO1lS t’ , f,~ riabtiB SVM-12 Balancing of Rigid and Flexible Rotors Neville F. Rieger Stress Technology, Inc. 1986 The Shock end Vibration...a bearing or other Atructural components by fatigue . Unbalance is therefore recognized as an important potential cause of machinery failure. A number...runout on slow rotation, stress relaxation with time often heavy vibration during rota- "tion Section of blade or vane broken Visually observable; bearing
Stability for the Lens Rigidity Problem
Bao, Gang; Zhang, Hai
2017-09-01
Let g be a Riemannian metric for R^d ({d ≥q 3}) which differs from the Euclidean metric only in a smooth and strictly convex bounded domain M. The lens rigidity problem is concerned with recovering the metric g inside M from the corresponding lens relation on the boundary {partial M}. In this paper, the stability of the lens rigidity problem is investigated for metrics which are a priori close to a given non-trapping metric satisfying the "strong fold-regular" condition. A metric g is called strong fold-regular if for each point {x\\in M}, there exists a set of geodesics passing through x whose conormal bundle covers {T^*xM}. Moreover, these geodesics contain either no conjugate points or only fold conjugate points with a non-degeneracy condition. Examples of strong fold-regular metrics are constructed. Our main result gives the first stability result for the lens rigidity problem in the case of anisotropic metrics which allow conjugate points. The approach is based on the study of the linearized inverse problem of recovering a metric from its induced geodesic flow, which is a weighted geodesic X-ray transform problem for symmetric 2-tensor fields. A key ingredient is to show that the kernel of the X-ray transform on symmetric solenoidal 2-tensor fields is of finite dimension. It remains open whether the kernel space is trivial or not.
Rigid internal fixation of infected mandibular fractures.
Mehra, Pushkar; Van Heukelom, Emily; Cottrell, David A
2009-05-01
To evaluate the treatment outcomes of rigid internal fixation for the management of infected mandible fractures. A retrospective chart review of infected mandible fractures managed by a single oral and maxillofacial surgeon at a level I trauma center during a 7-year period was accomplished by independent examiners. All patients were treated with incision and drainage, culture and sensitivity testing, extraction of nonsalvageable teeth, placement of maxillomandibular fixation when possible, fracture reduction with bone debridement and decortication, rigid internal fixation of the mandible by an extraoral approach, and antibiotic therapy. The medical and social history was contributory in most patients. The analysis was stratified by the differentiation of the fractures into 2 groups: those with soft tissue infections in the fracture region versus those with hard tissue-infected fractures (biopsy-proven osteomyelitis). A total of 44 patients were included in this study, with an average follow-up of 18.2 months from the date of surgery (range 3 to 48). The treatment protocol was successful in all 18 patients (100%) with soft tissue infected mandibular fractures and 24 (92%) of 26 patients with hard tissue-infected fractures. A protocol consisting of concomitant incision and drainage, mandibular debridement, fracture reduction, and stabilization with rigid internal fixation can be effectively used for single-stage management of infected mandible fractures.
21 CFR 886.5916 - Rigid gas permeable contact lens.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable...
Kneller, E. A.; Johnson, C. A.; Queffelec, T. A.; Nachtegaele, L.
2010-12-01
Non-rigid deformation in regions of continental extension and compression can lead to large lateral strain and changes in the shape and surface area of continental plates. This large lateral strain in turn leads to vertical strain in the lithosphere, which is a fundamental control on mechanical and thermal subsidence. Traditional plate reconstruction approaches only describe 2D changes in the shape of tectonic plates and do not include lateral strain gradients and vertical strain. Incorporating lateral and vertical strain into kinematic plate tectonic models is necessary for quantifying the past configuration of tectonic plates, modeling paleogeography and for linking subsidence and heat flow to lateral plate motion. Furthermore, traditional approaches are limited to describing processes at the surface of the Earth and cannot be used to investigate 3D slab kinematics. We build on previous work and overcome the limitations of traditional methods by developing an inverse non-rigid continuum-based plate reconstruction approach that links lateral plate tectonic motion to large-scale 4D deformation of continental plates and subducting slabs. We also describe how this approach can be implemented in open source 3D animation software that can be used to create extendable and easily maintained interactive tools. These tools allow the modeler to rapidly reconstruct deformation and map data and constrain plate models with 3D information. The methods presented in this work can improve paleogeographic reconstructions, help visualize complicated 4D deformation processes in a reconstructed framework, and constrain subsidence and lithospheric stretching, all of which are important for understanding thermal history and estimating heat flow in sedimentary basins.
Mawad, Ramy
2014-01-01
The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.
Influence of flock coating on bending rigidity of woven fabrics
Ozdemir, O.; Kesimci, M. O.
2017-10-01
This work presents the preliminary results of our efforts that focused on the effect of the flock coating on the bending rigidity of woven fabrics. For this objective, a laboratory scale flocking unit is designed and flocked samples of controlled flock density are produced. Bending rigidity of the samples with different flock densities are measured on both flocked and unflocked sides. It is shown that the bending rigidity depends on both flock density and whether the side to be measured is flocked or not. Adhesive layer thickness on the bending rigidity is shown to be dramatic. And at higher basis weights, flock density gets less effective on bending rigidity.
Cosmic Rays In The Magnetosphere, 2. Apparent Cut-off Rigidities and Coupling Functions
Dorman, L. I.; Danilova, O. A.; Iucci, N.; Parisi, M.; Ptitsyna, N. G.; Tyasto, M. I.; Villoresi, G.
We calculate the apparent cut-off rigidities along the survey Italy-Antarctica-Italy** on the basis of results of Danilova et al. (2001) on trajectory calculations for inclined cut- off rigidities at eight azimuths (through 45?) and five zeniths angles (through 15?) along the survey. For calculations of apparent cut-off rigidities we use also the infor- mation on integral multiplicities of secondary neutrons in dependence of zenith angle of incident primary cosmic ray particles, as theoretically computed. This information is based on the theoretical calculations of meson-nuclear cascades for primary protons with different rigidities arriving to the EarthSs atmosphere at different zenith angles (Dorman and Pakhomov, 1979). These results have been checked and normalized by using coupling functions obtained in the same survey [Dorman et al. (2000)]. The determined apparent cut-off rigidities have been compared with results obtained by Clem et al. (1997) and with those used by Dorman et al. (2000) computed by using vertical cut-off rigidities, for trajectories especially calculated for the survey. On the basis of the apparent cut-off rigidities along the latitude survey, the coupling functions for neutron monitor and bare neutron counters found by Dorman et al. (2000) are now determined more accurately. **Survey realized with logistic and financial support of the Italian Antarctic Program (PNRA) and with the co-operation of IFSI-CNR. REFERENCES: Clem, J.M., et al. J. Geophys. Res., 102, 26,919 (1997). Danilova, O.A., et al., Latitude survey in December 1996-March 1997, 1. Cut-off rigidities for different azimuth and zenith angles, Paper ST13, This issue (2001) Dorman L.I. and Pakhomov N.I., "The dependence of the integral generation multiplicity of neutron component at various depths in the atmosphere on zenith angle on primary particle in- cidence". Proc. 16-th ICRC, Kyoto, 4, 416-420 (1979) Dorman, L.I., et al., J. Geophys. Res. 105 , 21,047 (2000).
Brownian dynamics of confined rigid bodies
Energy Technology Data Exchange (ETDEWEB)
Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar, E-mail: donev@courant.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2015-10-14
We introduce numerical methods for simulating the diffusive motion of rigid bodies of arbitrary shape immersed in a viscous fluid. We parameterize the orientation of the bodies using normalized quaternions, which are numerically robust, space efficient, and easy to accumulate. We construct a system of overdamped Langevin equations in the quaternion representation that accounts for hydrodynamic effects, preserves the unit-norm constraint on the quaternion, and is time reversible with respect to the Gibbs-Boltzmann distribution at equilibrium. We introduce two schemes for temporal integration of the overdamped Langevin equations of motion, one based on the Fixman midpoint method and the other based on a random finite difference approach, both of which ensure that the correct stochastic drift term is captured in a computationally efficient way. We study several examples of rigid colloidal particles diffusing near a no-slip boundary and demonstrate the importance of the choice of tracking point on the measured translational mean square displacement (MSD). We examine the average short-time as well as the long-time quasi-two-dimensional diffusion coefficient of a rigid particle sedimented near a bottom wall due to gravity. For several particle shapes, we find a choice of tracking point that makes the MSD essentially linear with time, allowing us to estimate the long-time diffusion coefficient efficiently using a Monte Carlo method. However, in general, such a special choice of tracking point does not exist, and numerical techniques for simulating long trajectories, such as the ones we introduce here, are necessary to study diffusion on long time scales.
Rigid gas permeable lenses and patient management.
Terry, R; Schnider, C; Holden, B A
1989-01-01
The introduction of new rigid gas permeable (RGP) contact lens materials provides the practitioner with a number of alternatives for patient management. But whatever the lens materials used, problems related to the lenses, care and maintenance solutions, and patients may arise. This paper examines concerns such as parameter instability, durability of lenses, compatibility of materials and solutions, patient education and compliance, 3 and 9 o'clock staining, corneal distortion, and lid changes. Suggestions are made on ways to avoid or minimize problems related to RGP lens wear.
Mechanical Characterization of Rigid Polyurethane Foams
Energy Technology Data Exchange (ETDEWEB)
Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials
2014-12-01
Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.
Gabapentin for decerebrate rigidity: a case report.
Kao, Chuen-Der; Chen, Jen-Tse; Lai, Kuan-Lin; Chang, Jiun-Bin; Wu, Zin-An; Liao, Kwong-Kum
2008-01-01
A 48-year-old woman suddenly lost consciousness as a result of a right rostral pontine tegmentum haemorrhage. The patient presented with decerebrate rigidity (DR) and regained full consciousness 5 days after the initial onset. The patient was given gabapentin 1200 mg/day nasogastrically and her DR significantly improved, although other antiepileptic drugs such as phenytoin and carbamazepine were given in larger dosages to decrease muscle hypertonicity. The patients' preserved consciousness and motor-evoked potentials to transcranial magnetic stimulation indicated a derangement of the extrapyramidal tracts with preservation of the pyramidal tracts. This case report discusses the possible mechanisms of action of gabapentin in DR.
Vertebral Column Resection for Rigid Spinal Deformity.
Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G
2017-05-01
Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.
Public policies targeting labour market rigidities
Directory of Open Access Journals (Sweden)
Andreea Claudia ŞERBAN
2013-02-01
Full Text Available Labour market rigidity becomes an issue of increasing importance under conditions of shocks associated with the economic crisis due to the need to increase the adaptability and responsiveness to them. Thus, labour market policies must be directed towards mitigating rigidities caused by institutional or demographic factors or certain mismatch between demand and supply of education qualifications. This paper highlights the major role of the active labour market policies targeting the increase of labour flexibility, stressing the importance and impact on the ability to adapt quickly and effectively to macroeconomic shocks. Located on a declining trend in the years preceding the crisis, spending on labour market policies increased in 2009 in all the Member States of the European Union. Spending differences are significant between countries, Romania being at the lowest end of the European Union. This requires special attention because the increased adaptability of workers through training, as active measure, is of major importance considering the increased speed of changes in the labour market.
Thermally-Induced Structural Disturbances of Rigid Panel Solar Arrays
Johnston, John D.; Thornton, Earl A.
1997-01-01
The performance of a significant number of spacecraft has been impacted negatively by attitude disturbances resulting from thermally-induced motions of flexible structures. Recent examples of spacecraft affected by these disturbances include the Hubble Space Telescope (HST) and the Upper Atmosphere Research Satellite (UARS). Thermally-induced structural disturbances occur as the result of rapid changes in thermal loading typically initiated as a satellite exits or enters the Earth's shadow. Temperature differences in flexible appendages give rise to structural deformations, which in turn result in disturbance torques reacting back on the spacecraft. Structures which have proven susceptible to these disturbances include deployable booms and solar arrays. This paper investigates disturbances resulting from thermally-induced deformations of rigid panel solar arrays. An analytical model for the thermal-structural response of the solar array and the corresponding disturbance torque are presented. The effect of these disturbances on the attitude dynamics of a simple spacecraft is then investigated using a coupled system of governing equations which includes the effects of thermally-induced deformations. Numerical results demonstrate the effect of varying solar array geometry on the dynamic response of the system.
EGFR and HER2 activate rigidity sensing only on rigid matrices
Saxena, Mayur; Liu, Shuaimin; Yang, Bo; Hajal, Cynthia; Changede, Rishita; Hu, Junqiang; Wolfenson, Haguy; Hone, James; Sheetz, Michael P.
2017-07-01
Epidermal growth factor receptor (EGFR) interacts with integrins during cell spreading and motility, but little is known about the role of EGFR in these mechanosensing processes. Here we show, using two different cell lines, that in serum- and EGF-free conditions, EGFR or HER2 activity increase spreading and rigidity-sensing contractions on rigid, but not soft, substrates. Contractions peak after 15-20 min, but diminish by tenfold after 4 h. Addition of EGF at that point increases spreading and contractions, but this can be blocked by myosin-II inhibition. We further show that EGFR and HER2 are activated through phosphorylation by Src family kinases (SFK). On soft surfaces, neither EGFR inhibition nor EGF stimulation have any effect on cell motility. Thus, EGFR or HER2 can catalyse rigidity sensing after associating with nascent adhesions under rigidity-dependent tension downstream of SFK activity. This has broad implications for the roles of EGFR and HER2 in the absence of EGF both for normal and cancerous growth.
Earth materials and earth dynamics
Energy Technology Data Exchange (ETDEWEB)
Bennett, K; Shankland, T. [and others
2000-11-01
In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).
Parkinson's disease rigidity: relation to brain connectivity and motor performance
Directory of Open Access Journals (Sweden)
Nazanin eBaradaran
2013-06-01
Full Text Available Objective: 1 To determine the brain connectivity pattern associated with clinical rigidity scores in Parkinson's disease (PD and 2 to determine the relation between clinically-assessed rigidity and quantitative metrics of motor performance.Background: Rigidity, the resistance to passive movement, is exacerbated in PD by asking the subject to move the contralateral limb, implying that rigidity involves a distributed brain network. Rigidity mainly affects subjects when they attempt to move; yet the relation between clinical rigidity scores and quantitative aspects of motor performance are unknown.Methods: Ten clinically diagnosed PD patients (off medication and ten controls were recruited to perform an fMRI squeeze-bulb tracking task that included both visually guided and internally guided features. The direct functional connectivity between anatomically defined regions of interest was assessed with Dynamic Bayesian Networks (DBNs. Tracking performance was assessed by fitting Linear Dynamical System (LDS models to the motor performance, and was compared to the clinical rigidity scores. A cross-validated Least Absolute Shrinkage and Selection Operator (LASSO regression method was used to determine the brain connectivity network that best predicted clinical rigidity scores.Results: The damping ratio of the LDS models significantly correlated with clinical rigidity scores (p < 10-4. An fMRI connectivity network in subcortical and primary and premotor cortical regions accurately predicted clinical rigidity scores (p < 10-5. Conclusions: A widely distributed cortical/subcortical network is associated with rigidity observed in PD patients, which reinforces the importance of altered functional connectivity in the pathophysiology of PD. PD subjects with higher rigidity scores tend to have less overshoot in their tracking performance, and damping ratio may represent a robust, quantitative marker of the motoric effects of increasing rigidity.
MR findings of decerebrate rigidity with preservation of consciousness.
Kao, C-D; Guo, W-Y; Chen, J-T; Wu, Z-A; Liao, K-K
2006-05-01
We describe a case of decerebrate rigidity, with preservation of consciousness, caused by a discrete pontine tegmentum lesion identified on MR imaging. Lesions within a certain brain stem region are responsible for decerebrate rigidity in animal studies, but there has been a lack of MR imaging evidence in humans. This report also implies that a discrete lesion was responsible for the decerebrate rigidity, while consciousness was preserved.
Observational properties of rigidly rotating dust configurations
Ilyas, Batyr; Yang, Jinye
2016-01-01
We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust. We ask the question whether such solutions can describe astrophysical rotating dark matter clouds and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks in this space-time has several differences with respect to the emission of light from accretion disks around black holes. The shape of the iron K{\\alpha} line in the reflection spectrum of accretion disks can potentially distinguish this class of solution from the Kerr metric, but this may not be possible with current X-ray missions.
Settling dynamics of asymmetric rigid fibers
Tozzi, E. J.; Scott, C. T.; Vahey, D.; Klingenberg, D. J.
2011-03-01
The three-dimensional motion of asymmetric rigid fibers settling under gravity in a quiescent fluid was experimentally measured using a pair of cameras located on a movable platform. The particle motion typically consisted of an initial transient after which the particle approached a steady rate of rotation about an axis parallel to the acceleration of gravity, with its center of mass following a helical trajectory. Numerical and analytical methods were used to predict translational and angular velocities as well as the evolution of the fiber orientation as a function of time. A comparison of calculated and measured values shows that it is possible to quantitatively predict complex motions of particles that have highly asymmetric shape. The relations between particle shape and settling trajectory have potential applications for hydrodynamic characterization of fiber shapes and fiber separation.
Suspension of rigid spheres in shear flows
Rahmani, Mona; Esteghamatian, Amir; Wachs, Anthony
2017-11-01
Suspension of rigid spheres in a plane Couette flow is studied using three-dimensional particle resolved numerical simulations. We use a fixed mesh that resolves each particle diameter using 24 points and a Distributed Lagrange Multi- plier/Fictitious Domain (DLM/FD) method. The effects of particle volume fraction and particle Reynolds number on the macrcoscopic and microscopic stresses in the suspension are examined. The kinematics of particle are also studied for a range of dilute to dense suspensions and Stokes to inertial flows. For dense suspensions and also for higher particle Reynolds numbers the particle/particle and particle/wall contacts are enhanced. For such cases, lubrication forces need to be taken into account. We compare simulations with and without the lubrication forces to conclude for what range of parameters lubrication should be incorporated into the simulations.
On real structures on rigid surfaces
Energy Technology Data Exchange (ETDEWEB)
Kulikov, Vik S [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation); Kharlamov, V M [Institut de Recherche Matematique Avanee Universite Louis Pasteur et CNRS 7 rue Rene Descartes (France)
2002-02-28
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p{sub g}=q=0 and K{sup 2}=9. These surfaces also provide new counterexamples to the 'Dif = Def' problem.
Advanced Rigid Ablative Thermal Protection Systems
Feldman, J. D.; Gasch, M. J.; Poteet, C. C.; Szalai, Christine
2012-01-01
With the gradual increase in robotic rover sophistication and the desire for humans to explore the solar system, the need for reentry systems to deliver large payloads into planetary atmospheres is looming. Heritage ablative Thermal Protection Systems (TPS) using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for many future missions. Significant advances in TPS materials technology are needed in order to enable susequent human exploration missions. This paper summarizes some recent progress at NASA in developing families of advanced rigid ablative TPS that could be used for thermal protection in planetary entry missions. In particular, the effort focuses on technologies required to land heavy masses on Mars to facilitate exploration.
Observational properties of rigidly rotating dust configurations
Energy Technology Data Exchange (ETDEWEB)
Ilyas, Batyr; Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Yang, Jinye [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Bambi, Cosimo [Fudan University, Center for Field Theory and Particle Physics and Department of Physics, Shanghai (China); Eberhard-Karls Universitaet Tuebingen, Theoretical Astrophysics, Tuebingen (Germany)
2017-07-15
We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust (i.e. non-interacting particles). We ask the question whether such solutions can describe astrophysical rotating dark matter clouds near the center of galaxies and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks made of ordinary baryonic matter in this space-time has several differences with respect to the emission of light from similar accretion disks around black holes. The shape of the iron Kα line in the reflection spectrum of accretion disks can potentially distinguish this class of solutions from the Kerr metric, but this may not be possible with current X-ray missions. (orig.)
Digital Earth - A sustainable Earth
Mahavir
2014-02-01
All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.
Rigid-only versus combined rigid and flexible percutaneous nephrolithotomy: a systematic review.
Cracco, Cecilia M; Knoll, Thomas; Liatsikos, Evangelos N; Osther, Palle J; Smith, Arthur D; Scarpa, Roberto M; Scoffone, Cesare M
2017-08-01
Percutaneous nephrolithotomy (PNL) is usually performed worldwide with a rigid-only antegrade approach. Daily practice suggests that adding flexible nephroscopy and/or ureteroscopy to conventional rigid PNL might improve its efficacy and safety, but available evidence is weak. Appraisal of reliable outcomes of such PNL techniques would better guide intraoperative choices and optimize surgical results. Therefore, our objective was to systematically review relevant literature comparing the outcomes of rigid-only PNL and combined flexible PNLs (adding flexible nephroscopy and/or flexible ureteroscopy) for the treatment of large and/or complex upper urinary tract calculi, with regard to efficacy and safety. Ovid MedLine, PubMed, Scopus and Web of Science databases were searched in August 2016 to identify relevant studies. Article selection was performed according to the Preferred Reporting Items for Systematic Review and Meta-analysis criteria. Six articles reporting on 666 patients were included: two randomized controlled trials, two retrospective comparative studies and two case series ≥50 patients (one prospective and one retrospective). A narrative synthesis of minor evidences was also prepared. The adjunct of flexible nephroscopy and/or ureteroscopy provided better stone-free rates (range 86.7-96.97%), through a single percutaneous access most of the times and in any position, reducing the need for second-look procedures. Safety of the combined flexible procedures was improved to a variable degree, with a consensual reduction of the mean hospital stay (range 5.1-7 days). The current evidence suggests that patients with large and/or complex urolithiasis might benefit from the adjunct of flexible nephroscopy and/or ureteroscopy to rigid PNL.
Anti-synchronization of the rigid body exhibiting chaotic dynamics ...
African Journals Online (AJOL)
Anti-synchronization of the rigid body exhibiting chaotic dynamics. ... Journal of the Nigerian Association of Mathematical Physics ... Global asymptotic stability and convergence of the sum of the dynamical variables representing the Eulerian state space of the two rigid bodies was verified by numerical simulations. JONAMP ...
effects of flexural rigidity of reinforcement bars on the fundamental ...
African Journals Online (AJOL)
NIJOTECH
2009-09-02
Sep 2, 2009 ... numerical method, and the results show that the flexural rigidity of the bars has significant effect on the fundamental natural frequency of heavily reinforced concrete sections. KEYWORDS: Fundamental Natural Frequency, Reinforced Concrete Slab, Flexural Rigidity,. Reinforcement Bars. INTRODUCTION.
Conflict and creativity: Threat-rigidity or motivated focus
de Dreu, C.K.W.; Nijstad, B.A.
2008-01-01
According to the traditional threat-rigidity reasoning, people in social conflict will be less flexible, less creative, more narrow-minded, and more rigid in their thinking when they adopt a conflict rather than a cooperation mental set. The authors propose and test an alternative, motivated focus
Non-rigid registration by geometry-constrained diffusion
DEFF Research Database (Denmark)
Andresen, Per Rønsholt; Nielsen, Mads
2001-01-01
Assume that only partial knowledge about a non-rigid registration is given: certain points, curves, or surfaces in one 3D image are known to map to certain points, curves, or surfaces in another 3D image. In trying to identify the non-rigid registration field, we face a generalized aperture problem...
The relationship between torsional rigidity and bending strength ...
African Journals Online (AJOL)
The modulus of rigidity, G, and bending moment of elasticity, MOE, of SA pine are evaluated from a direct torsion test and bending tests. Specimens were subjected to a series of tests with the view to determining direct torsional rigidity, apparent bending modulus of elasticity and pure bending modulus of elasticity. Torsional ...
Tautochrone and Brachistochrone Shape Solutions for Rocking Rigid Bodies
Glaschke, Patrick
2016-01-01
Rocking rigid bodies appear in several shapes in everyday life: As furniture like rocking chairs and rocking cradles or as toys like rocking horses or tilting dolls. The familiar rocking motion of these objects, a non-linear combination of a rigid rotation and a translation of the center of mass, gives rise to a number of interesting dynamical properties. However, their study has received little attention in the literature. This work presents a comprehensive introduction to the dynamics of rocking rigid bodies, including a concise derivation of the equations of motion as well as a general inversion procedure to construct rocking rigid body shapes with specified dynamical properties. Moreover, two novel rigid body shapes are derived - the tautochrone shape and the brachistochrone shape - which represent an intriguing generalization of the well-know tautochrone and brachistochrone curves. In particular, tautochrone shapes offer an alternative construction of a tautochrone pendulum, in addition to Huygens' cyclo...
The theory of pseudo-rigid bodies
Cohen, Harley
1988-01-01
This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else where, much of the work is new. Our objective in writing this mono graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not ent...
Spontaneous droplet trampolining on rigid superhydrophobic surfaces
Schutzius, Thomas M.; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos
2015-11-01
Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces.
Molecular rigidity and enthalpy-entropy compensation in DNA melting.
Vargas-Lara, Fernando; Starr, Francis W; Douglas, Jack F
2017-10-23
Enthalpy-entropy compensation (EEC) is observed in diverse molecular binding processes of importance to living systems and manufacturing applications, but this widely occurring phenomenon is not sufficiently understood from a molecular physics standpoint. To gain insight into this fundamental problem, we focus on the melting of double-stranded DNA (dsDNA) since measurements exhibiting EEC are extensive for nucleic acid complexes and existing coarse-grained models of DNA allow us to explore the influence of changes in molecular parameters on the energetic parameters by using molecular dynamics simulations. Previous experimental and computational studies have indicated a correlation between EEC and changes in molecular rigidity in certain binding-unbinding processes, and, correspondingly, we estimate measures of DNA molecular rigidity under a wide range of conditions, along with resultant changes in the enthalpy and entropy of binding. In particular, we consider variations in dsDNA rigidity that arise from changes of intrinsic molecular rigidity such as varying the associative interaction strength between the DNA bases, the length of the DNA chains, and the bending stiffness of the individual DNA chains. We also consider extrinsic changes of molecular rigidity arising from the addition of polymer additives and geometrical confinement of DNA between parallel plates. All our computations confirm EEC and indicate that this phenomenon is indeed highly correlated with changes in molecular rigidity. However, two distinct patterns relating to how DNA rigidity influences the entropy of association emerge from our analysis. Increasing the intrinsic DNA rigidity increases the entropy of binding, but increases in molecular rigidity from external constraints decreases the entropy of binding. EEC arises in numerous synthetic and biological binding processes and we suggest that changes in molecular rigidity might provide a common origin of this ubiquitous phenomenon in the mutual
Observations on the Partial Breaking of $N=2$ Rigid Supersymmetry
Andrianopoli, Laura; Ferrara, Sergio; Trigiante, Mario
2015-01-01
We study the partial breaking of $N=2$ rigid supersymmetry for a generic rigid special geometry of $n$ abelian vector multiplets in the presence of Fayet-Iliopoulos terms induced by the Hyper-K\\"ahler momentum map. By exhibiting the symplectic structure of the problem we give invariant conditions for the breaking to occur, which rely on a quartic invariant of the Fayet-Iliopoulos charges as well as on a modification of the $N=2$ rigid symmetry algebra by a vector central charge.
Near field acoustic holography with microphones on a rigid sphere
DEFF Research Database (Denmark)
Jacobsen, Finn; Moreno-Pescador, Guillermo; Fernandez Grande, Efren
2011-01-01
Spherical near field acoustic holography (spherical NAH) is a technique that makes it possible to reconstruct the sound field inside and just outside a spherical surface on which the sound pressure is measured with an array of microphones. This is potentially very useful for source identification....... The sphere can be acoustically transparent or it can be rigid. A rigid sphere is somewhat more practical than an open sphere. However, spherical NAH based on a rigid sphere is only valid if it can be assumed that the sphere has a negligible influence on the incident sound field, and this is not necessarily...
Observations on the partial breaking of N=2 rigid supersymmetry
Directory of Open Access Journals (Sweden)
Laura Andrianopoli
2015-05-01
Full Text Available We study the partial breaking of N=2 rigid supersymmetry for a generic rigid special geometry of n abelian vector multiplets in the presence of Fayet–Iliopoulos terms induced by the hyper-Kähler momentum map. By exhibiting the symplectic structure of the problem we give invariant conditions for the breaking to occur, which rely on a quartic invariant of the Fayet–Iliopoulos charges as well as on a modification of the N=2 rigid symmetry algebra by a vector central charge.
Sound propagation over rigid porous layers
Howorth, Craig
Two related topics are discussed: (1) the measurement of the acoustical characteristics of rigid porous materials, that is the impedance and propagation constant; and (2) the propagation of sound over the surface of a hard backed layer of such a material. A review of impedance measurement leads to the selection of an indirect method which is employed successfully on a wide range of surfaces. A numerical comparison of impedance models follows including a one-parameter semi-empirical model, a phenomenological model, and a microstructural model which relates several physical parameters of a material to the acoustical properties of a surface. The models differ in their prediction of the acoustical properties of a low porosity material. A numerical comparison of the solutions of point source propagation in the presence of a porous media indicates that the 'extended' Weyl van der Pol approximation is reliable over short source receiver distances. The study is extended to examine the phenomenon of the acoustical surface wave. Three experimental techniques are used to produce new evidence for the existence of such a wave which shows good agreement with the theoretical predictions. The indirect method is used to obtain impedances and model parameters for a wide variety of surfaces varying from soils to fiberglass and which are compared with the results of an impedance technique and with standing wave tube measurements. The indirect method of impedance is employed together with the microstructural model and the propagation model examined earlier in studies of the acoustical properties of porous road surfaces. It proves possible to use the indirect method both to determine the microstructural parameters and to classify the acoustical properties of such a previous surface when the sound source is either a loudspeaker point source or a vehicle. The results of the parameter determination are validated by a series of non-acoustical measurements. With regard only to the excess
Glass fiber and silica reinforced rigid polyurethane foams
National Research Council Canada - National Science Library
M W Kim; S H Kwon; H Park; B K Kim
2017-01-01
Ternary composites of rigid polyurethane foam (RPUF)/glass fiber/silica as well as RPUF/glass fiber have been fabricated from glass fiber, silica, polymeric 4,4'-di-phenylmethane diisocyanate (PMDI...
Stabilization of Rigid Body Dynamics by Internal and External Torques
National Research Council Canada - National Science Library
Bloch, A. M; Krishnaprasad, P. S; Marsden, J. E; Sanchez de Alvarez, G
1990-01-01
...] with quadratic feedback torques for internal rotors. We show that with such torques, the equations for the rigid body with momentum wheels are Hamiltonian with respect to a Lie-Poisson bracket structure. Further...
Resin Infusion Rigidized Inflatable Concept Development and Demonstration Project
National Aeronautics and Space Administration — Utilizing resin infusion to rigidize an inflatable structure and form fiber-reinforced composites on-orbit is a novel concept that builds on current NASA technology...
A Concise Introduction to Mechanics of Rigid Bodies Multidisciplinary Engineering
Huang, L
2012-01-01
A Concise Introduction to Mechanics of Rigid Bodies: Multidisciplinary Engineering presents concise, key concepts of kinematics and dynamics of rigid bodies. This compact volume bridges the steep gap between introductory texts on engineering mechanics, which focus on one and two dimensional motions of particles and rigid bodies, and advanced texts on multi-body dynamics in high dimension spaces found in multidisciplinary areas like mechatronics, robotics and biomechanics. In the book, rigid body motions in the spaces with different dimensions are described in addition to studies in a uniform framework supported by vector and matrix operations. Rigorous mathematic tools and explanations are provided to clarify the most complex concepts. This book also: Provides practical examples from different engineering areas, offering a link between theoretical fundamentals and everyday applications Offers simplified mathematical equations to clearly present essential theories in robotics and mechanics Presents statics...
[Arterial rigidity in patients with chronic obstructive pulmonary disease].
Karoli, N A; Dolishniaia, G R; Rebrov, A P
2012-01-01
The aim of this open study was to estimate arterial rigidity in patients with chronic obstructive pulmonary disease (COPD). It included 105 patients above 40 years of age. Exclusion criteria were clinical signs of CHD, peripheral atherosclerosis, and other severe chronic diseases in the exacerbation phase. The control group was comprised of 27 practically healthy volunteers. The arterial fluid was detected using a Tensioclinic arteriograph (Tensiomed, Hungary). Arterial rigidity was estimated in patients of two age groups (below and above 60 years) with COPD of different severity The results suggest the development of arterial wall lesions in proportion to the patients' age and COPD severity. It was shown that excessive arterial rigidity and accelerated pulse wave reflection (increased speed of pulse wave propagation and augmentation index) exert significant influence on the elevation of central arterial pressure. Enhanced rigidity of the arterial wall being a cardiovascular risk factor further prospective studies are needed.
Dynamic Simulation of Rigid Guide Structure Based on ANSYS
National Research Council Canada - National Science Library
Zhang Xin; Wang Zhe
2017-01-01
... commonly used calculation model of rigid guide and bunton by ANSYS. Simulation of the horizontal force through a section of the guide evenly, and the deflection curves of each model are obtained...
Invariant scrambled sets, uniform rigidity and weak mixing
Foryś, Magdalena; Huang, Wen; Li, Jian; Oprocha, Piotr
2014-01-01
We show that for a non-trivial transitive dynamical system, it has a dense Mycielski invariant strongly scrambled set if and only if it has a fixed point, and it has a dense Mycielski invariant $\\delta$-scrambled set for some $\\delta>0$ if and only if it has a fixed point and not uniformly rigid. We also provide two methods for the construction of completely scrambled systems which are weakly mixing, proximal and uniformly rigid.
Observability/Identifiability of Rigid Motion under Perspective Projection
Soatto, Stefano
1994-01-01
The "visual motion estimation" problem concerns the reconstruction of the motion of an object viewed under projection. This paper addresses the feasibility of such a problem when the object is represented as a "rigid" set of point-features in the Euclidean 3D space. We represent rigid motion as a point on the so-called "essential manifold" and show that it is globally observable from perspective projections under some general position conditions. Such conditions hold when the path of the view...
On the inertial motions of liquid-filled rigid bodies
Mazzone, Giusy; Galdi, Giovanni; Zunino, Paolo
2013-11-01
We consider a rigid body with a cavity completely filled by a viscous liquid and study the inertial motions of the system liquid-filled rigid body S . The equations governing the motion of this coupled system are given by the Navier-Stokes equations and the equations of the balance of the total angular momentum of S in absence of external forces and torques. Given any initial motion to the coupled system, characterized by an initial relative velocity of the fluid and an initial total angular momentum, we give a complete description of the behavior that the system liquid-filled rigid body will show at large times. From both analytical and numerical viewpoints, we are able to prove a longstanding conjecture stated by Zhukovskii, namely that S will eventually reach a steady state which is a rigid body permanent rotation. In other words, the liquid goes to rest with respect to the rigid body and the coupled system will rotate as a whole rigid body, with a constant angular velocity that is directed along one of the principal axes of inertia of the system.
Rigidity analysis of protein biological assemblies and periodic crystal structures
2013-01-01
Background We initiate in silico rigidity-theoretical studies of biological assemblies and small crystals for protein structures. The goal is to determine if, and how, the interactions among neighboring cells and subchains affect the flexibility of a molecule in its crystallized state. We use experimental X-ray crystallography data from the Protein Data Bank (PDB). The analysis relies on an effcient graph-based algorithm. Computational experiments were performed using new protein rigidity analysis tools available in the new release of our KINARI-Web server http://kinari.cs.umass.edu. Results We provide two types of results: on biological assemblies and on crystals. We found that when only isolated subchains are considered, structural and functional information may be missed. Indeed, the rigidity of biological assemblies is sometimes dependent on the count and placement of hydrogen bonds and other interactions among the individual subchains of the biological unit. Similarly, the rigidity of small crystals may be affected by the interactions between atoms belonging to different unit cells. We have analyzed a dataset of approximately 300 proteins, from which we generated 982 crystals (some of which are biological assemblies). We identified two types of behaviors. (a) Some crystals and/or biological assemblies will aggregate into rigid bodies that span multiple unit cells/asymmetric units. Some of them create substantially larger rigid cluster in the crystal/biological assembly form, while in other cases, the aggregation has a smaller effect just at the interface between the units. (b) In other cases, the rigidity properties of the asymmetric units are retained, because the rigid bodies did not combine. We also identified two interesting cases where rigidity analysis may be correlated with the functional behavior of the protein. This type of information, identified here for the first time, depends critically on the ability to create crystals and biological assemblies
General terms and rigidity: another solution to the trivialization problem
Directory of Open Access Journals (Sweden)
Eleonora Orlando
2014-06-01
Full Text Available In this paper I am concerned with the problem of applying the notion of rigidity to general terms. In Naming and Necessity, Kripke has clearly suggested that we should include some general terms among the rigid ones, namely, those common nouns semantically correlated with natural substances, species and phenomena, in general, natural kinds -'water', 'tiger', 'heat'- and some adjectives -'red', 'hot', 'loud'. However, the notion of rigidity has been defined for singular terms; after all, the notion that Kripke has provided us with is the notion of a rigid designator. But general terms do not designate single individuals: rather, they apply to many of them. In sum, the original concept of rigidity cannot be straightforwardly applied to general terms: it has to be somehow redefined in order to make it cover them. As is known, two main positions have been put forward to accomplish that task: the identity of designation conception, according to which a rigid general term is one that designates the same property or kind in all possible worlds, and the essentialist conception, which conceives of a rigid general term as an essentialist one, namely, a term that expresses an essential property of an object. My purpose in the present paper is to defend a particular version of the identity of designation conception: on the proposed approach, a rigid general term will be one that expresses the same property in all possible worlds and names the property it expresses. In my opinion, the position can be established on the basis of an inference to the best explanation of our intuitive interpretation and evaluation, relative to counterfactual circumstances, of statements containing different kinds of general terms, which is strictly analogous to our intuitive interpretation and evaluation, relative to such circumstances, of statements containing different kinds of singular ones. I will argue that it is possible to offer a new solution to the trivialization
Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.
Energy Technology Data Exchange (ETDEWEB)
Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-06-01
Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.
Maguinness, Corrina; Newell, Fiona N
2015-04-01
There is growing evidence to suggest that facial motion is an important cue for face recognition. However, it is poorly understood whether motion is integrated with facial form information or whether it provides an independent cue to identity. To provide further insight into this issue, we compared the effect of motion on face perception in two developmental prosopagnosics and age-matched controls. Participants first learned faces presented dynamically (video), or in a sequence of static images, in which rigid (viewpoint) or non-rigid (expression) changes occurred. Immediately following learning, participants were required to match a static face image to the learned face. Test face images varied by viewpoint (Experiment 1) or expression (Experiment 2) and were learned or novel face images. We found similar performance across prosopagnosics and controls in matching facial identity across changes in viewpoint when the learned face was shown moving in a rigid manner. However, non-rigid motion interfered with face matching across changes in expression in both individuals with prosopagnosia compared to the performance of control participants. In contrast, non-rigid motion did not differentially affect the matching of facial expressions across changes in identity for either prosopagnosics (Experiment 3). Our results suggest that whilst the processing of rigid motion information of a face may be preserved in developmental prosopagnosia, non-rigid motion can specifically interfere with the representation of structural face information. Taken together, these results suggest that both form and motion cues are important in face perception and that these cues are likely integrated in the representation of facial identity. Copyright © 2015 Elsevier Ltd. All rights reserved.
Brush, Stephen G.
1980-09-01
In 1896 when Emil Wiechert proposed his model of the Earth with an iron core and stony shell, scientists generally believed that the entire earth was a solid as rigid as steel. R. D. Oldham's identification of P and S waves in seismological records allowed him to detect a discontinuity corresponding to a boundary between core and shell (mantle) in 1906, and Beno Gutenberg established the depth of this boundary as 2900 km. But failure to detect propagation of S waves through the core was not sufficient evidence to persuade seismologists that it is fluid (contrary to modern textbook statements). Not until 1926 did Harold Jeffreys refute the arguments for solidity and establish that the core is liquid. In 1936 Inge Lehmann discovered the small inner core. K. E. Bullen argued, on the basis of plausible assumptions about compressibility and density, that the inner core is solid. Attempts to find seismic signals that have passed through the inner core as S waves have so far failed (with one possible exception), but analysis of free oscillations provided fairly convincing evidence for its solidity.
Efficient computation of root mean square deviations under rigid transformations.
Hildebrandt, Anna K; Dietzen, Matthias; Lengauer, Thomas; Lenhof, Hans-Peter; Althaus, Ernst; Hildebrandt, Andreas
2014-04-15
The computation of root mean square deviations (RMSD) is an important step in many bioinformatics applications. If approached naively, each RMSD computation takes time linear in the number of atoms. In addition, a careful implementation is required to achieve numerical stability, which further increases runtimes. In practice, the structural variations under consideration are often induced by rigid transformations of the protein, or are at least dominated by a rigid component. In this work, we show how RMSD values resulting from rigid transformations can be computed in constant time from the protein's covariance matrix, which can be precomputed in linear time. As a typical application scenario is protein clustering, we will also show how the Ward-distance which is popular in this field can be reduced to RMSD evaluations, yielding a constant time approach for their computation. Copyright © 2014 Wiley Periodicals, Inc.
Correlated rigidity percolation and gelation of colloidal particles
Zhang, Shang; Zhang, Leyou; Rocklin, D. Zeb; Mao, Xiaoming
Rigidity percolation on a lattice with sites or bonds randomly diluted is controlled by the isostatic point, where the degrees of freedom and constraints balance, and the system is at the verge of mechanical instability. In the case of triangular lattice rigidity percolation occurs very close to p = 2 / 3 as predicted from isostaticity. Interestingly, we found that when the site dilution is correlated, this transition occurs at a lower p, meaning that less material is needed for rigidity in the disordered structure. This correlation may be seen as a consequence of short range attraction between the particles which makes them cluster. We characterized critical scaling associated with the site correlation parameter, and will discuss implication to understand experimental systems such as gelation of colloidal particles.
Interaction of the rigid journal with Newtonian fluid
Michal, Havlásek; František, Pochylý
2017-09-01
This paper deals with the problem of identification of added effects of incompressible Newtonian fluid that impacts on the rigid journal performing translational motion. It considers two degrees of freedom. The axial motion of the rigid journal was neglected. It assumes small oscillations and linear model. The task was solved for two geometrical configurations of the computational domain. In the first variant of geometry, there is no flow between the bases of journal and stator. The second variant of geometry also allows liquid to flow in space between the bases of journal and stator. The introduction describes the mathematical model for the identification of added mass, damping and stiffness matrices. On the basis of the mathematical model and computational modeling of velocity and pressure fields using CFD, the force components are determined. From there, the mentioned matrices are determined depending on the eccentricity of the rigid journal.
A concise introduction to mechanics of rigid bodies multidisciplinary engineering
Huang, L
2017-01-01
This updated second edition broadens the explanation of rotational kinematics and dynamics — the most important aspect of rigid body motion in three-dimensional space and a topic of much greater complexity than linear motion. It expands treatment of vector and matrix, and includes quaternion operations to describe and analyze rigid body motion which are found in robot control, trajectory planning, 3D vision system calibration, and hand-eye coordination of robots in assembly work, etc. It features updated treatments of concepts in all chapters and case studies. The textbook retains its comprehensiveness in coverage and compactness in size, which make it easily accessible to the readers from multidisciplinary areas who want to grasp the key concepts of rigid body mechanics which are usually scattered in multiple volumes of traditional textbooks. Theoretical concepts are explained through examples taken from across engineering disciplines and links to applications and more advanced courses (e.g. industrial rob...
Friction effects on lateral loading behavior of rigid piles
DEFF Research Database (Denmark)
Zania, Varvara; Hededal, Ole
2012-01-01
The adequacy of the p -y curves used in the current practice for the design of rigid pile foundations with large diameter, like in the case of monopile foundations of offshore wind turbines, has been widely questioned. The current study aims at analyzing the lateral behavior of rigid piles, while...... taking into account the shear frictional resistance along the pile. For this purpose efficient three dimensional finite element models of different diameter have been developed. The increase of the side friction and of the diameter of the pile is shown to alter the failure pattern and increase...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...
Toxicity evaluation and hazard review for Rigid Foam
Energy Technology Data Exchange (ETDEWEB)
Archuleta, M.M.; Stocum, W.E.
1994-02-01
Rigid Foam is a chemical delay foam used to completely encapsulate an object or to block access to an area. Prior studies have indicated that the final foam product is essentially non-toxic. The purpose of this study was to evaluate and summarize the current chemical and toxicological data available on the components of Rigid Foam and to update the information available on the toxicity of the final Rigid Foam product. Since the possibility exists for a partial deployment of Rigid Foam where only one of the components is released, this study also examined the toxicity of its chemical constituents. Rigid Foam is composed of an {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} Component. The {open_quotes}A{close_quotes} component is primarily a polymeric isocyanate and the {open_quotes}B{close_quotes} component is a mixture of polyols. In addition to the primary constituents, dichlorodifluoromethane and trichlorofluoromethane are present as blowing agents along with catalysts and silicone surfactants necessary for foaming. The pre-deployed {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} components are stored in separate vessels and are brought together in static mixing nozzles for dispersal. The results of this evaluation indicate that a completely deployed Rigid Foam under normal conditions is essentially non-toxic as determined previously. However, in the event of a partial deployment or deployment of an individual component directly at an unprotected individual, the degree of hazard is increased due to the toxic and corrosive nature of the individual constituents. The health hazard would depend on the properties of the material to which the person was exposed.
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.
Shear-induced rigidity in spider silk glands
Koski, Kristie J.; McKiernan, Keri; Akhenblit, Paul; Yarger, Jeffery L.
2012-09-01
We measure the elastic stiffnesses of the concentrated viscous protein solution of the dehydrated Nephila clavipes major ampullate gland with Brillouin light scattering. The glandular material shows no rigidity but possesses a tensile stiffness similar to that of spider silk. We show, however, that with application of a simple static shear, the mechanical properties of the spider gland protein mixture can be altered irreversibly, lowering symmetry and enabling shear waves to be supported, thus, giving rise to rigidity and yielding elastic properties similar to those of the naturally spun (i.e., dynamically sheared) silk.
Quadratic Twists of Rigid Calabi–Yau Threefolds Over
DEFF Research Database (Denmark)
Gouvêa, Fernando Q.; Kiming, Ian; Yui, Noriko
2013-01-01
We consider rigid Calabi–Yau threefolds defined over Q and the question of whether they admit quadratic twists. We give a precise geometric definition of the notion of a quadratic twists in this setting. Every rigid Calabi–Yau threefold over Q is modular so there is attached to it a certain newform...... of weight 4 on some Γ 0(N). We show that quadratic twisting of a threefold corresponds to twisting the attached newform by quadratic characters and illustrate with a number of obvious and not so obvious examples. The question is motivated by the deeper question of which newforms of weight 4 on some Γ 0(N...
Non-rigid image registration using bone growth model
DEFF Research Database (Denmark)
Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven
1997-01-01
Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change...... between time sequence images of the human mandible. By being able to register the images, this paper at the same time contributes to the validation of the growth model, which is based on the currently available medical theories and knowledge...
Rigid 4D N=2 supersymmetric backgrounds and actions
Energy Technology Data Exchange (ETDEWEB)
Butter, Daniel; Inverso, Gianluca; Lodato, Ivano [Nikhef Theory Group,Science Park 105, 1098 XG Amsterdam (Netherlands)
2015-09-15
We classify all N=2 rigid supersymmetric backgrounds in four dimensions with both Lorentzian and Euclidean signature that preserve eight real supercharges, up to discrete identifications. Among the backgrounds we find specific warpings of S{sup 3}×ℝ and AdS{sub 3}×ℝ, AdS{sub 2}×S{sup 2} and H{sup 2}×S{sup 2} with generic radii, and some more exotic geometries. We provide the generic two-derivative rigid vector and hypermultiplet actions and analyze the conditions imposed on the special Kähler and hyperkähler target spaces.
High Resolution Quantification of Cellular Forces for Rigidity Sensing
Liu, Shuaimin
This thesis describes a comprehensive study of understanding the mechanism of rigidity sensing by quantitative analysis using submicron pillar array substrates. From mechanobiology perspective, we explore and study molecular pathways involved in rigidity and force sensing at cell-matrix adhesions with regard to cancer, regeneration, and development by quantification methods. In Chapter 2 and 3, we developed fabrication and imaging techniques to enhance the performance of a submicron pillar device in terms of spatial and temporal measurement ability, and we discovered a correlation of rigidity sensing forces and corresponding proteins involved in the early rigidity sensing events. In Chapter 2, we introduced optical effect arising from submicron structure imaging, and we described a technique to identify the correct focal plane of pillar tip by fabricating a substrate with designed-offset pillars. From calibration result, we identified the correct focal plane that was previously overlooked, and verified our findings by other imaging techniques. In Chapter 3, we described several techniques to selectively functionalize elastomeric pillars top and compared these techniques in terms of purposes and fabrication complexity. Techniques introduced in this chapter included direct labeling, such as stamping of fluorescent substances (organic dye, nano-diamond, q-dot) to pillars top, as well as indirect labeling that selectively modify the surface of molds with either metal or fluorescent substances. In Chapter 4, we examined the characteristics of local contractility forces and identified the components formed a sarcomere like contractile unit (CU) that cells use to sense rigidity. CUs were found to be assembled at cell edge, contain myosin II, alpha-actinin, tropomodulin and tropomyosin (Tm), and resemble sarcomeres in size (˜2 mum) and function. Then we performed quantitative analysis of CUs to evaluate rigidity sensing activity over ˜8 hours time course and found that
Accuracy limit of rigid 3-point water models
Izadi, Saeed
2016-01-01
Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed. PMID:27544113
Buffers Affect the Bending Rigidity of Model Lipid Membranes
DEFF Research Database (Denmark)
Bouvrais, H.; Duelund, L.; Ipsen, J. H.
2014-01-01
vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning...
Flexibility versus rigidity in the practice of Islamic Family law
N.Y. Shehada (Nahda)
2009-01-01
textabstractThe last decades have witnessed a sustained critique of the mainstream Orientalist notion that classical Islamic family law was rigid, inflexible, and homogeneous. Many historians have used innovative methods to demonstrate that jurists and judges in precodification times enjoyed the
Rigidity of unilateral external fixators - A biomechanical study
P.T.P.W. Burgers (Paul); M.P.J.M. Riel (Marcel); L.M.M. Vogels (Lucas); R.W. Stam (Ronald); P. Patka (Peter); E.M.M. van Lieshout (Esther)
2011-01-01
textabstractIntroduction: External fixation is the primary choice of temporary fracture stabilisation for specific polytrauma patients. Adequate initial fracture healing requires sufficient stability at the fracture site. The purpose of this study was to compare the rigidity of the Dynafix
Behaviour and Modelling of Semi-rigid Structural Frame Systems ...
African Journals Online (AJOL)
A computational finite element model is developed to predict the load-deflection characteristic of portal frames with semi-rigid welded and bolted joints. Plate components of frame ... The modelling of friction effect between the contact surfaces of bolted joints is verified to be the most important factor. The comparative analysis ...
Dielectric relaxation phenomena of rigid polar liquid molecules ...
Indian Academy of Sciences (India)
The dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyltrichloroacetate () in benzene, -hexane and -heptane () under 4.2, 9.8 and 24.6 GHz electric ﬁelds at 30°C are studied to show the possible existence of double relaxation times 2 and 1 for rotations of the whole and the ﬂexible ...
Rigid Biobased Building Blocks: Current Developments and Outlook
Es, van D.S.
2013-01-01
In this perspectives paper we will look at the state-of-the-art in rigid renewable building blocks for biobased materials, with a focus on two types of carbohydrate-based difunctional monomers, i.e.,isohexides and furan-2,5-dicarboxylic acid (FDCA).
Wrist rigidity assessment during Deep Brain Stimulation surgery.
Costa, Pedro; Rosas, Maria José; Vaz, Rui; Cunha, João Paulo
2015-01-01
Parkinson's Disease (PD) patients often need Deep Brain Stimulation (DBS) surgery when they become intolerant to drugs or these lose efficiency. A stimulation electrode is implanted in the basal ganglia to promote the functional control of the deregulated dopaminergic motor pathways. The stimulation target is defined by medical imaging, followed by electrophysiological inspection for fine electrode position trimming and electrical stimulation tuning. Intra-operative stimulation of the target and the evaluation of wrist rigidity allows to choose the stimulation parameters which best alleviate PD symptoms without side effects. Neurologists impose a passive wrist flexion movement and qualitatively describe the perceived decrease in rigidity under different voltages, based on its experience and with subjectivity. We designed a novel, comfortable and wireless wearable motion sensor to classify the wrist rigidity by deriving a robust signal descriptor from angular speed values and a polynomial mathematical model to classify signals using a quantitative continuous scale. The descriptor significantly (pwrist rigidity, improving upon the inherent subjective clinical evaluation while using small, simple and easy to use motion sensor.
A mixed elastoplastic/rigid-plastic material model
Huetink, Han; van den Boogaard, Antonius H.; Rietman, Bert; Lof, J.; Meinders, Vincent T.
1999-01-01
In forming process simulations, the rigid-plastic material model is widely used because of its numerically robust behaviour. The model yields accurate results, as long as the strain increments are large compared to the elastic limit strain. In cases where the strain increments are small e.g. in dead
The rigid pendulum - an antique but evergreen physical model
Butikov, Eugene I.
1999-11-01
Various kinds of motion of a rigid pendulum (including swinging with arbitrarily large amplitudes and complete revolutions) are investigated both analytically and with the help of computerized simulations. The simulation experiments reveal many interesting peculiarities of this famous physical model and complement the analytical study of the subject in a manner that is mutually reinforcing.
Substructural Identification of Flexural Rigidity for Beam-Like Structures
Directory of Open Access Journals (Sweden)
Ki-Young Koo
2015-01-01
Full Text Available This study proposes a novel substructural identification method based on the Bernoulli-Euler beam theory with a single variable optimization scheme to estimate the flexural rigidity of a beam-like structure such as a bridge deck, which is one of the major structural integrity indices of a structure. In ordinary bridges, the boundary condition of a superstructure can be significantly altered by aging and environmental variations, and the actual boundary conditions are generally unknown or difficult to be estimated correctly. To efficiently bypass the problems related to boundary conditions, a substructural identification method is proposed to evaluate the flexural rigidity regardless of the actual boundary conditions by isolating an identification region within the internal substructure. The proposed method is very simple and effective as it utilizes the single variable optimization based on the transfer function formulated utilizing Bernoulli Euler beam theory for the inverse analysis to obtain the flexural rigidity. This novel method is also rigorously investigated by applying it for estimating the flexural rigidity of a simply supported beam model with different boundary conditions, a concrete plate-girder bridge model with different length of an internal substructure, a cantilever-type wind turbine tower structure with different type of excitation, and a steel box-girder bridge model with internal structural damages.
Numerical rigid plastic modelling of shear capacity of keyed joints
DEFF Research Database (Denmark)
Herfelt, Morten Andersen; Poulsen, Peter Noe; Hoang, Linh Cao
2015-01-01
Keyed shear joints are currently designed using simple and conservative design formulas, yet these formulas do not take the local mechanisms in the concrete core of the joint into account. To investigate this phenomenon a rigid, perfectly plastic finite element model of keyed joints is used. The ...
Impulsive and rigid temperament subtypes and executive functioning
African Journals Online (AJOL)
The results indicate that the rigid temperament subtype reacted slower to both complex (executive functioning) and less complex tasks (attention and working memory) than the impulsive temperament subtype. ... Significant differences were maintained with analyses of intelligence and parental education as covariates.
Rigid rod spaced fullerene as building block for nanoclusters
Indian Academy of Sciences (India)
By using phenylacetylene based rigid-rod linkers (PhA), we have successfully synthesized two fullerene derivatives, C60-PhA and C60-PhA-C60. The absorption spectral features of C60, as well as that of the phenylacetylene moiety are retained in the monomeric forms of these fullerene derivatives, ruling out the possibility ...
On the mechanism of gas transport in rigid polymer membranes
Hensema, E.R.; Hensema, E.R.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.
1993-01-01
Conventional polymers are compared as gas separation membrane materials with tailormade polymers. The increased permeability of the latter are due to their higher free volume available for gas transport. The increased free volume is associated with the rigidity polymer backbone. Free volume is
Assessment of Lumped-Parameter Models for Rigid Footings
DEFF Research Database (Denmark)
Andersen, Lars
2010-01-01
The quality of consistent lumped-parameter models of rigid footings is examined. Emphasis is put on the maximum response during excitation and the geometrical damping related to free vibrations. The optimal order of a lumped-parameter model is determined for each degree of freedom, i.e. horizontal...
Design of the new rigid endoscope distortion measurement system
Zhai, Xiaohao; Liu, Xiaohua; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin; Wang, Yakun; Li, Yonghui; Zhou, Peng
2015-08-01
Endoscopic imaging quality affects industrial safety and medical security. Rigid endoscope distortion is of great signification as one of optical parameters to evaluate the imaging quality. This paper introduces a new method of rigid endoscope distortion measurement, which is different from the common methods with low accuracy and fussy operation. It contains a Liquid Crystal Display (LCD) to display the target, a CCD to obtain the images with distortion, and a computer to process the images. The LCD is employed instead of common white screen. The autonomous control system of LCD makes it showing the test target designed for distortion, and its parameter is known. LCD control system can change the test target to satisfy the different demand for accuracy, which avoids replacing target frequently. The test system also contains a CCD to acquire images in the exit pupil position of rigid endoscope. Rigid endoscope distortion is regarded as centrosymmetric, and the MATLAB software automatically measures it by processing the images from CCD. The MATLAB software compares target images with that without distortion on LCD and calculates the results. Relative distortion is obtained at different field of view (FOV) radius. The computer plots the curve of relative distortion, abscissa means radius of FOV, ordinate means relative distortion. The industry standard shows that, the distortion at 70% field of view is pointed on the curve, which can be taken as an evaluation standard. This new measuring method achieves advantages of high precision, high degree of intelligence, excellent repeatability and gets calculation results quickly.
Patient satisfaction related to rigid external distraction osteogenesis
van Eggermont, Bas; Jansma, J.; Bierman, M. W. J.; Stegenga, B.
2007-01-01
The aim of this study was to evaluate satisfaction with treatment among cleft lip and palate patients who underwent maxillary advancement using a rigid external distraction (RED) device. Nine patients (four boys, five girls), mean age 17.7 years (SD 4.0), were included in the study. Outcome measures
Nonlinear optical properties of rigid-rod polymers
Trimmer, Mark S.; Wang, Ying
1992-01-01
The purpose of this research project was to integrate enhanced third order nonlinear optical (NLO) properties, especially high x(exp (3)) (greater than 10(exp -8) esu), into Maxdem's novel conjugated rigid-rod polymers while retaining their desirable processing, mechanical, and thermal properties. This work primarily involved synthetic approaches to optimized materials.
Rigidly connected magnetic lines: twisting and winding of magnetic lines
Prasad, G.
2017-10-01
The dynamical process of magnetic flux variation in a fluid's stream tube is described by constructing 1+1+ (2) decomposition of the gradient of fluid's 4-velocity. The necessary and sufficient conditions are obtained for a spacelike congruence to be a congruence of rigidly connected spacelike curves. The evolution of magnetic flux in a magnetic tube is explored under the assumptions that magnetic lines are rigidly connected and the chemical potential of the fluid is constant along a magnetic tube. The interplay between magnetic and stream tubes is demonstrated. It is shown that the growth of magnetic energy in a magnetic tube cannot exceed to that of a stream tube. It is found that the proper time variation of twist of magnetic lines is caused by gravitation inside a neutron star if magnetic lines are rigidly connected and charge neutrality condition holds. Helmholtz-like magnetic vorticity flux conservation in a magnetic tube constituted by rigidly connected geodetic magnetic lines is derived under the assumption that the charge neutrality condition holds. It is shown that the winding of frozen-in poloidal magnetic field due to differential rotation requires meridional circulation in an axisymmetric stationary hydromagnetic configuration.
Rigid-plastic seismic design of reinforced concrete structures
DEFF Research Database (Denmark)
Costa, Joao Domingues; Bento, R.; Levtchitch, V.
2007-01-01
In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime ...
Behaviour and Modelling of Semi-rigid Structural Frame Systems ...
African Journals Online (AJOL)
A computational finite element model is developed to predict the load-deflection characteristic of portal frames with semi-rigid welded and bolted joints. Plate components of frame members and joints are modelled by thin shell finite elements while bolt connectors by springs with the force-deformation characteristic ...
Influence of rigid boundary on the propagation of torsional surface ...
Indian Academy of Sciences (India)
The present work illustrates a theoretical study on the effect of rigid boundary for the propagation of torsional surface wave in an inhomogeneous crustal layer over an inhomogeneous half space. It is believed that the inhomogeneity in the half space arises due to hyperbolic variation in shear modulus and density whereas ...
Connect-disconnect coupling for preadjusted rigid shafts
Bajkowski, F. W.; Holmberg, A.
1969-01-01
Coupling device enables a rigid shaft to be connected to or disconnected from a fixed base without disturbing the point of adjustment of the shaft in a socket or causing the shaft to rotate. The coupling consists of an externally threaded, internally slotted boss extending from the fixed base.
Mizuno, Ichiro; Komiya, Akira; Watanabe, Akihiko; Fuse, Hideki
2010-01-01
The aim of this prospective study was to evaluate the usefulness of measurement of axial penile rigidity, compared with radial penile rigidity. Twenty-two patients, aged 21-75 years old (a mean of 50), with erectile dysfunction underwent axial penile rigidity measurements by the digital inflection rigidometer (DIR) as well as radial penile rigidity measurements by the RigiScan Plus during intracavernous pharmacological erection testing. A significant correlation was recognized between axial rigidity, and radial rigidity at the tip (p = 0.0024) and base (p = 0.0098) of the penis. In 10 patients, the DIR revealed axial rigidity of 550 g or more, and they also had radial rigidity of 60% or more at the tip and base. In 14 and 17 subjects, radial rigidity of 60% or more was observed at the tip and base, respectively. Four of the former 14 and 7 of the latter 17 had axial rigidity <550 g. A RigiScan results of radial rigidity of 60% or more should be interpreted cautiously and not necessarily regarded as normal. Copyright (c) 2010 S. Karger AG, Basel.
Earth mortars and earth-lime renders
Directory of Open Access Journals (Sweden)
Maria Fernandes
2008-01-01
Full Text Available Earth surface coatings play a decorative architectural role, apart from their function as wall protection. In Portuguese vernacular architecture, earth mortars were usually applied on stone masonry, while earth renders and plasters were used on indoors surface coatings. Limestone exists only in certain areas of the country and consequently lime was not easily available everywhere, especially on granite and schist regions where stone masonry was a current building technique. In the central west coast of Portugal, the lime slaking procedure entailed slaking the quicklime mixed with earth (sandy soil, in a pit; the resulting mixture would then be combined in a mortar or plaster. This was also the procedure for manufactured adobes stabilized with lime. Adobe buildings with earth-lime renderings and plasters were also traditional in the same region, using lime putty and lime wash for final coat and decoration. Classic decoration on earth architecture from the 18th-19th century was in many countries a consequence of the François Cointeraux (1740-1830 manuals - Les Cahiers d'Architecture Rurale" (1793 - a French guide for earth architecture and building construction. This manual arrived to Portugal in the beginning of XIX century, but was never translated to Portuguese. References about decoration for earth houses were explained on this manual, as well as procedures about earth-lime renders and ornamentation of earth walls; in fact, these procedures are exactly the same as the ones used in adobe buildings in this Portuguese region. The specific purpose of the present paper is to show some cases of earth mortars, renders and plasters on stone buildings in Portugal and to explain the methods of producing earth-lime renders, and also to show some examples of rendering and coating with earth-lime in Portuguese adobe vernacular architecture.
Initial Development of an Electronic Testis Rigidity Tester
Directory of Open Access Journals (Sweden)
Petros Mirilas
2011-01-01
Full Text Available We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT, into an electronic system (Electronic Testis Rigidity Tester, ETRT by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded “insight“ of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.
Deformable registration of multi-modal data including rigid structures
Energy Technology Data Exchange (ETDEWEB)
Huesman, Ronald H.; Klein, Gregory J.; Kimdon, Joey A.; Kuo, Chaincy; Majumdar, Sharmila
2003-05-02
Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result
DEFF Research Database (Denmark)
Wolff, Stefan
2006-01-01
, Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...
Towards accurate modeling of noncovalent interactions for protein rigidity analysis.
Fox, Naomi; Streinu, Ileana
2013-01-01
Protein rigidity analysis is an efficient computational method for extracting flexibility information from static, X-ray crystallography protein data. Atoms and bonds are modeled as a mechanical structure and analyzed with a fast graph-based algorithm, producing a decomposition of the flexible molecule into interconnected rigid clusters. The result depends critically on noncovalent atomic interactions, primarily on how hydrogen bonds and hydrophobic interactions are computed and modeled. Ongoing research points to the stringent need for benchmarking rigidity analysis software systems, towards the goal of increasing their accuracy and validating their results, either against each other and against biologically relevant (functional) parameters. We propose two new methods for modeling hydrogen bonds and hydrophobic interactions that more accurately reflect a mechanical model, without being computationally more intensive. We evaluate them using a novel scoring method, based on the B-cubed score from the information retrieval literature, which measures how well two cluster decompositions match. To evaluate the modeling accuracy of KINARI, our pebble-game rigidity analysis system, we use a benchmark data set of 20 proteins, each with multiple distinct conformations deposited in the Protein Data Bank. Cluster decompositions for them were previously determined with the RigidFinder method from Gerstein's lab and validated against experimental data. When KINARI's default tuning parameters are used, an improvement of the B-cubed score over a crude baseline is observed in 30% of this data. With our new modeling options, improvements were observed in over 70% of the proteins in this data set. We investigate the sensitivity of the cluster decomposition score with case studies on pyruvate phosphate dikinase and calmodulin. To substantially improve the accuracy of protein rigidity analysis systems, thorough benchmarking must be performed on all current systems and future
The Lifeworld Earth and a Modelled Earth
Juuti, Kalle
2014-01-01
The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…
The ‘twin paradox’ in relativistic rigid motion
Ben-Ya'acov, Uri
2016-09-01
Relativistic rigid motion suggests a new version for the so-called ‘twin paradox’, comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being rigid, is simultaneously at rest, the twins’ ages, measured as the proper-times along their individual world lines, are different when they are located at remote parts of the spaceship. The age, or proper-time, difference depends on the distance at rest between the astronauts and the rapidity difference between start to end. The relation of the age difference with the relative Doppler shift of light signals transmitted between the astronauts and implications for the possibility to assign a common age (proper-time) to complex, spatially extended, relativistic systems are also discussed.
A density-independent rigidity transition in biological tissues
Bi, Dapeng; Lopez, J. H.; Schwarz, J. M.; Manning, M. Lisa
2015-12-01
Cell migration is important in many biological processes, including embryonic development, cancer metastasis and wound healing. In these tissues, a cell’s motion is often strongly constrained by its neighbours, leading to glassy dynamics. Although self-propelled particle models exhibit a density-driven glass transition, this does not explain liquid-to-solid transitions in confluent tissues, where there are no gaps between cells and therefore the density is constant. Here we demonstrate the existence of a new type of rigidity transition that occurs in the well-studied vertex model for confluent tissue monolayers at constant density. We find that the onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension, providing an explanation for liquid-to-solid transitions in confluent tissues and making testable predictions about how these transitions differ from those in particulate matter.
LENUS (Irish Health Repository)
Ahmad, Nasir Zaheer
2012-06-01
Rigid sigmoidoscopy is sometimes performed at first presentation in colorectal clinics. We assessed the feasibility of flexible sigmoidoscopy in similar situations by comparing it with rigid sigmoidoscopy as a first investigative tool.
On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue
Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.
2016-01-01
Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \
NOLB: Nonlinear Rigid Block Normal Mode Analysis Method
Hoffmann, Alexandre; Grudinin, Sergei
2017-01-01
International audience; We present a new conceptually simple and computationally efficient method for non-linear normal mode analysis called NOLB. It relies on the rotations-translations of blocks (RTB) theoretical basis developed by Y.-H. Sanejouand and colleagues. We demonstrate how to physically interpret the eigenvalues computed in the RTB basis in terms of angular and linear velocities applied to the rigid blocks and how to construct a non-linear extrapolation of motion out of these velo...
Alternative Material Dowel Bars for Rigid Pavement Joints
ECT Team, Purdue
2007-01-01
Over the last thirty to forty years, dowel support of the joint in Rigid Joint Pavement (RJP) has been widely used. The problem of deterioration of concrete pavement joints has resulted in the search for alternate solutions. Fiber-reinforced polymer (FRP) and stainless steel represent corrosion resistant alternatives to conventional galvanized steel in this application. The recently study by the FHWA of Alternative Materials for Highway Construction demonstrated that even with extended wet-dr...
Nonlinear dynamics mathematical models for rigid bodies with a liquid
Lukovsky, Ivan A
2015-01-01
This book is devoted to analytically approximate methods in the nonlinear dynamics of a rigid body with cavities partly filled by liquid. It combines several methods and compares the results with experimental data. It is useful for experienced and early-stage readers interested in analytical approaches to fluid-structure interaction problems, the fundamental mathematical background and modeling the dynamics of such complex mechanical systems.
Stability characterizations of fixtured rigid bodies with Coulomb friction
Energy Technology Data Exchange (ETDEWEB)
PANG,J.S.; TRINKLE,JEFFREY C.
2000-02-15
This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.
Oscillation of a rigid rod in the special relativity
Paiva, F M
2012-01-01
In the special relativity, a rigid rod slides upon itself, with one extremity oscillating harmonically. We discovered restrictions in the amplitude of the motion and in the length of the rod, essential to eliminate unphysical solutions. ------- Cxe la speciala relativeco, rigida stango movigxas sur si mem, kun unu fino oscilante harmonie. Ni malkovris limigajn kondicxojn pri la amplitudo de movado kaj pri la longo de stango, necesegaj por elimini ne-fizikajn solvojn.
As-Rigid-As-Possible molecular interpolation paths
Nguyen, Minh Khoa; Jaillet, Léonard; Redon, Stéphane
2017-04-01
This paper proposes a new method to generate interpolation paths between two given molecular conformations. It relies on the As-Rigid-As-Possible (ARAP) paradigm used in Computer Graphics to manipulate complex meshes while preserving their essential structural characteristics. The adaptation of ARAP approaches to the case of molecular systems is presented in this contribution. Experiments conducted on a large set of benchmarks show how such a strategy can efficiently compute relevant interpolation paths with large conformational rearrangements.
Rigid bronchoscOpic dilatation of postintubation tracheal stenosis
African Journals Online (AJOL)
trice, dilatation percutanée, dilatation bronchospique rigide, dilatation de la technologie des ﬁbres optiques de la bulle ct. Nd;YAG (neodymium yttritium - aluminium garnet) la théra- pie laser avec ou sans le stenting. Méthodes: Trois malade du sexe féminins avec une histoire des périodes diverscs d'intubation endotrachée ...
Rigidity theorem for Willmore surfaces in a sphere
Indian Academy of Sciences (India)
compact non-minimal flat Willmore surfaces in S3, and Castro and Urbano [2] constructed many compact non-minimal Willmore surfaces in S4. In [6], Li obtained the following rigidity theorem for Willmore surfaces in a unit sphere. Theorem A. Let M be a compact Willmore surface in S2+p. Then. ∫M ρ2 (2 − 2B ρ2) dv ≤ 0,.
A model of the soft tissue artefact rigid component.
Camomilla, V; Bonci, T; Dumas, R; Chèze, L; Cappozzo, A
2015-07-16
When using stereophotogrammetry and skin-markers, the reconstruction of skeletal movement is affected by soft-tissue artefact (STA). This may be described by considering a marker-cluster as a deformable shape undergoing a geometric transformation formed by a non-rigid (change in size and shape) and a rigid component (translation and rotation displacements). A modal decomposition of the STA, relative to an appropriately identified basis, allows the separation of these components. This study proposes a mathematical model of the STA that embeds only its rigid component and estimates the relevant six mode amplitudes as linear functions of selected proximal and distal joint rotations during the analysed task. This model was successfully calibrated for thigh and shank using simultaneously recorded pin- and skin-marker data of running volunteers. The root mean square difference between measured and model-estimated STA rigid component was 1.1(0.8)mm (median (inter-quartile range) over 3 subjects × 5 trials × 33 markers coordinates), and it was mostly due to the wobbling not included in the model. Knee joint kinematics was estimated using reference pin-marker data and skin-marker data, both raw and compensated with the model-estimated STA. STA compensation decreased inaccuracy on average from 6% to 1% for flexion/extension, from 43% to 18% for the other two rotations, and from 69% to 25% for the linear displacements. Thus, the proposed mathematical model provides an STA estimate which can be effectively used within optimal bone pose and joint kinematics estimators for artefact compensation, and for simulations aimed at their comparative assessments. Copyright © 2015 Elsevier Ltd. All rights reserved.
Crack identification for rigid pavements using unmanned aerial vehicles
Bahaddin Ersoz, Ahmet; Pekcan, Onur; Teke, Turker
2017-09-01
Pavement condition assessment is an essential piece of modern pavement management systems as rehabilitation strategies are planned based upon its outcomes. For proper evaluation of existing pavements, they must be continuously and effectively monitored using practical means. Conventionally, truck-based pavement monitoring systems have been in-use in assessing the remaining life of in-service pavements. Although such systems produce accurate results, their use can be expensive and data processing can be time consuming, which make them infeasible considering the demand for quick pavement evaluation. To overcome such problems, Unmanned Aerial Vehicles (UAVs) can be used as an alternative as they are relatively cheaper and easier-to-use. In this study, we propose a UAV based pavement crack identification system for monitoring rigid pavements’ existing conditions. The system consists of recently introduced image processing algorithms used together with conventional machine learning techniques, both of which are used to perform detection of cracks on rigid pavements’ surface and their classification. Through image processing, the distinct features of labelled crack bodies are first obtained from the UAV based images and then used for training of a Support Vector Machine (SVM) model. The performance of the developed SVM model was assessed with a field study performed along a rigid pavement exposed to low traffic and serious temperature changes. Available cracks were classified using the UAV based system and obtained results indicate it ensures a good alternative solution for pavement monitoring applications.
A Convertible Spinal Orthosis for Controlled Torso Rigidity
Directory of Open Access Journals (Sweden)
Nicole I. Kern
2013-01-01
Full Text Available A traditional spinal orthosis in conjunction with a hip-knee-ankle-foot orthosis (HKAFO improves posture in persons with paraplegia during standing and walking. It also limits the wearer's range of motion when worn during other activities, such as vehicle transfer or sitting and reaching for objects. In order to regain full torso flexibility the user would need to remove the spinal orthosis which can be arduous and time consuming. A Convertible Spinal Orthosis (CSO that allows the user to switch between Locked rigid torso support and Unlocked free motion has been designed, fabricated and tested. It shows promise for increasing functionality, wear time and subject comfort. Analysis of movement has been performed with an able-bodied and a paraplegic subject wearing a rigid spinal orthosis, the CSO in both states, and without any bracing. Configuration state had the most impact on lateral bending. Mean values for the paraplegic subject of 27°, 38°, 48°, and 48° and for the able-bodied subject of 22°, 26°, 48°, and 45° were found for lateral bending of the upper torso relative to the thighs in the Rigid, Locked, Unlocked, and No-Brace states, respectively.
Symmetrical Parameterization of Rigid Body Transformations for Biomolecular Structures.
Kim, Jin Seob; Chirikjian, Gregory S
2018-01-01
Assessing preferred relative rigid body position and orientation is important in the description of biomolecular structures (such as proteins) and their interactions. In this article, we extend and apply the "symmetrical parameterization," which we recently introduced in the kinematics community, to address problems in structural biology. We also review parameterization methods that are widely used in structural biology to describe relative rigid body motions (in particular, orientations) as a basis for comparison. The new symmetrical parameterization is useful in describing the relative biomolecular rigid body motions, where the parameters are symmetrical in the sense that the subunits of a complex biomolecular structure are described in the same way for the corresponding motion and its inverse. The properties of this new parameterization, singularity analysis, and inverse kinematics are also investigated in more detail. Finally, parameterization is applied to real biomolecular structures and a potential application to structure modeling of symmetric macromolecules to show the efficacy of the symmetrical parameterization in the field of computational structural biology.
Chiral Orientation of Skeletal Muscle Cells Requires Rigid Substrate
Directory of Open Access Journals (Sweden)
Ninghao Zhu
2017-06-01
Full Text Available Reconstitution of tissue morphology with inherent left–right (LR asymmetry is essential for tissue/organ functions. For skeletal muscle, the largest tissue in mammalian organisms, successful myogenesis requires the regulation of the LR asymmetry to form the appropriate muscle alignment. However, the key factor for reproducing the LR asymmetry of skeletal tissues in a controllable, engineering context remains largely unknown. Recent reports indicate that cell chirality may underlie the LR development in tissue morphogenesis. Here, we report that a rigid substrate is required for the chirality of skeletal muscle cells. By using alternating micropatterned cell-adherent and cell-repellent stripes on a rigid substrate, we found that C2C12 skeletal muscle myoblasts exhibited a unidirectional tilted orientation with respect to the stripe boundary. Importantly, such chiral orientation was reduced when soft substrates were used instead. In addition, we demonstrated the key role of actin stress fibers in the formation of the chiral orientation. This study reveals that a rigid substrate is required for the chiral pattern of myoblasts, paving the way for reconstructing damaged muscle tissue with inherent LR asymmetry in the future.
Green waste cooking oil-based rigid polyurethane foam
Enderus, N. F.; Tahir, S. M.
2017-11-01
Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.
Coarse-grained rigid blob model for soft matter simulations.
Chao, Sheng D; Kress, Joel D; Redondo, Antonio
2005-06-15
We have developed a coarse-grained multiscale molecular simulation method for soft matter systems that directly incorporates stereochemical information. We divide the material into disjoint groups of atoms or particles that move as separate rigid bodies; we call these groups "rigid blobs," hence the name coarse-grained rigid blob model. The method is enabled by the construction of transferable interblob potentials that approximate the net intermolecular interactions, as obtained from ab initio electronic structure calculations, other all-atom empirical potentials, experimental data, or any combination of the above. We utilize a multipolar expansion to obtain the interblob potential-energy functions. The series, which contains controllable approximations that allow us to estimate the errors, approaches the original intermolecular potential as the number of terms increases. Using a novel numerical algorithm, we can calculate the interblob potentials very efficiently in terms of a few interaction moment tensors. This reduces the labor well beyond what is required in standard molecular-dynamics calculations and allows large-scale simulations for temporal scales commensurate with characteristic times of nano- and mesoscale systems. A detailed derivation of the formulas is presented, followed by illustrative applications to several systems showing that the method can effectively capture realistic microscopic details and can easily extend to large-scale simulations.
Operator Algebras in Rigid C*-Tensor Categories
Jones, Corey; Penneys, David
2017-11-01
In this article, we define operator algebras internal to a rigid C*-tensor category C. A C*/W*-algebra object in C is an algebra object A in ind-C whose category of free modules {FreeMod_C(A)} is a C-module C*/W*-category respectively. When C= Hilb_fd, the category of finite dimensional Hilbert spaces, we recover the usual notions of operator algebras. We generalize basic representation theoretic results, such as the Gelfand-Naimark and von Neumann bicommutant theorems, along with the GNS construction. We define the notion of completely positive morphisms between C*-algebra objects in C and prove the analog of the Stinespring dilation theorem. As an application, we discuss approximation and rigidity properties, including amenability, the Haagerup property, and property (T) for a connected W*-algebra M in C. Our definitions simultaneously unify the definitions of analytic properties for discrete quantum groups and rigid C*-tensor categories.
Integrable Problems of the Dynamics of Coupled Rigid Bodies
Bogoyavlenskiĭ, O. I.
1993-06-01
Several classical problems of dynamics are shown to be integrable for the special systems of coupled rigid bodies introduced in this paper and called Ck-central configurations. It is proved that the dynamics of an arbitrary Ck-central configuration in the Newtonian gravitational field with an arbitrary quadratic potential is integrable in the Liouville sense and in theta-functions of Riemann surfaces. A hidden symmetry of the inertial dynamics of these configurations is found, and reductions of the corresponding Lagrange equations to the Euler equations on the direct sums of Lie coalgebras SO(3) are obtained. Reductions and integrable cases of the equations for the rotation of a heavy Ck-central configuration about a fixed point are indicated. Separation of rotations of a space station type orbiting system, which is a Ck-central configuration of rigid bodies, is proved. This result leads to the possibility of independent stabilization of rotations of the rigid bodies in such orbiting configurations. Integrability of the inertial dynamics of CRn-central configurations of coupled gyrostats is proved.
Predicting Protein Hinge Motions and Allostery Using Rigidity Theory
Sljoka, Adnan; Bezginov, Alexandr
2011-11-01
Understanding how a 3D structure of a protein functions depends on predicting which regions are rigid, and which are flexible. One recent approach models molecules as a structure of fixed units (atoms with their bond angles as rigid units, bonds as hinges) plus biochemical constraints coming from the local geometry. This generates a `molecular graph' in the theory of combinatorial rigidity. The 6|V|-6 counting condition for 3-dimensional body-hinge structures (modulo molecular theorem), and a fast `pebble game' algorithm which tracks this count in the multigraph, have led to the development of the program FIRST, for rapid predictions of the flexibility of proteins. In this study we develop a novel protein hinge prediction algorithm via our extension of the pebble game algorithm (relevant regions detection algorithm). We have tested our hinge prediction algorithm on several proteins chosen from the dataset of manually annotated hinges available on the MOLMOV server. Many of our predictions are in very good agreement with this data set. Our algorithms can also predict `allosteric' interactions in proteins—where binding on one site of a molecule changes the shape or binding at a distance `active site' of the molecule. We also give some promising results which support the sliding piston-like movement of helices with respect to one another as a plausible mechanism by which GCPR receptors propagate conformational changes across membranes.
On the Existence and Utility of Rigid Quasilocal Frames
Epp, Richard J; McGrath, Paul L
2013-01-01
The notion of a rigid quasilocal frame (RQF) provides a geometrically natural way to define a system in general relativity, and a new way to analyze the problem of motion. An RQF is defined as a two-parameter family of timelike worldlines comprising the boundary (topologically R x S^2) of the history of a finite spatial volume, with the rigidity conditions that the congruence of worldlines be expansion- and shear-free. In other words, the size and shape of the system do not change. In previous work, such systems in Minkowski space were shown to admit precisely the same six degrees of freedom of rigid body motion that we are familiar with in Newtonian space-time, without any constraints, circumventing a century-old theorem due to Herglotz and Noether. This is a consequence of the fact that a two-sphere of any shape always admits precisely six conformal Killing vector fields, which generate an action of the Lorentz group on the sphere. Here we review the previous work in flat spacetime and extend it in three di...
Measuring membrane rigidity and viscosity: New methods, and new insights
Parthasarathy, Raghuveer
2014-03-01
Lipid membranes are remarkable materials: flexible, two-dimensional fluids whose physical properties guide cellular function. Bending rigidity and viscosity are two of the key mechanical parameters that characterize membranes. Both, however, are challenging to measure. I describe improvements in experimental techniques to quantify the bending modulus and the two-dimensional viscosity of lipid membranes. First, I show that using selective plane illumination microscopy (SPIM, also known as light sheet fluorescence microscopy) to image the thermal fluctuations of freely suspended giant lipid vesicles enables straightforward measurements of membrane rigidity, and also provides insights into changes in rigidity induced by cargo trafficking proteins. Second, I show that tracking both the rotational and translational diffusion of membrane-anchored tracer particles allows quantification of membrane viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer sizes, due presumably to a wide variety of couplings to the membrane. I also provide an example of protein-mediated changes in lipid viscosity.
The diagnostic role of thoracoscope in undiagnosed pleural effusion: Rigid versus flexible
Directory of Open Access Journals (Sweden)
Mostafa Mahmoud Abdel Mageid Shaheen
2014-07-01
Conclusions: Thoracoscopy using either fibreoptic bronchoscope or rigid thoracoscope is safe and well tolerated. Rigid thoracoscope has a higher diagnostic yield, easier handling, better orientation and is less expensive. Nevertheless, fibreoptic bronchoscope is an alternative technique if rigid thoracoscopy is not available.
National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....
National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...
A supplementary note on constructing the general Earth's rotation theory
Brumberg, Victor A.; Ivanova, Tamara V.
2014-07-01
Representing a post-scriptum supplementary to a previous paper of the authors Brumberg & Ivanova (2011) this note aims to simplify the practical development of the Earth's rotation theory, in the framework of the general planetary theory, avoiding the non-physical secular terms and involving the separation of the fast and slow angular variables, both for planetary-lunar motion and Earth's rotation. In this combined treatment of motion and rotation, the fast angular terms are related to the mean orbital longitudes of the bodies, the diurnal and Euler rotations of the Earth. The slow angular terms are due to the motions of pericenters and nodes, as well as the precession of the Earth. The combined system of the equations of motion for the principal planets and the Moon and the equations of the Earth's rotation is reduced to the autonomous secular system with theoretically possible solution in a trigonometric form. In the above-mentioned paper, the Earth's rotation has been treated in Euler parameters. The trivial change of the Euler parameters to their small declinations from some nominal values may improve the practical efficiency of the normalization of the Earth's rotation equations. This technique may be applied to any three-axial rigid planet. The initial terms of the corresponding expansions are given in the Appendix.
Passive Earth Entry Vehicle Landing Test
Kellas, Sotiris
2017-01-01
Two full-scale passive Earth Entry Vehicles (EEV) with realistic structure, surrogate sample container, and surrogate Thermal Protection System (TPS) were built at NASA Langley Research Center (LaRC) and tested at the Utah Test and Training Range (UTTR). The main test objective was to demonstrate structural integrity and investigate possible impact response deviations of the realistic vehicle as compared to rigid penetrometer responses. With the exception of the surrogate TPS and minor structural differences in the back shell construction, the two test vehicles were identical in geometry and both utilized the Integrated Composite Stiffener Structure (ICoSS) structural concept in the forward shell. The ICoSS concept is a lightweight and highly adaptable composite concept developed at NASA LaRC specifically for entry vehicle TPS carrier structures. The instrumented test vehicles were released from a helicopter approximately 400 m above ground. The drop height was selected such that at least 98% of the vehicles terminal velocity would be achieved. While drop tests of spherical penetrometers and a low fidelity aerodynamic EEV model were conducted at UTTR in 1998 and 2000, this was the first time a passive EEV with flight-like structure, surrogate TPS, and sample container was tested at UTTR for the purpose of complete structural system validation. Test results showed that at a landing vertical speed of approximately 30 m/s, the test vehicle maintained structural integrity and enough rigidity to penetrate the sandy clay surface thus attenuating the landing load, as measured at the vehicle CG, to less than 600 g. This measured deceleration was found to be in family with rigid penetrometer test data from the 1998 and 2000 test campaigns. Design implications of vehicle structure/soil interaction with respect to sample container and sample survivability are briefly discussed.
Sim, Jaehyun; Sim, Jun; Park, Eunsung; Lee, Julian
2015-06-01
Many proteins undergo large-scale motions where relatively rigid domains move against each other. The identification of rigid domains, as well as the hinge residues important for their relative movements, is important for various applications including flexible docking simulations. In this work, we develop a method for protein rigid domain identification based on an exhaustive enumeration of maximal rigid domains, the rigid domains not fully contained within other domains. The computation is performed by mapping the problem to that of finding maximal cliques in a graph. A minimal set of rigid domains are then selected, which cover most of the protein with minimal overlap. In contrast to the results of existing methods that partition a protein into non-overlapping domains using approximate algorithms, the rigid domains obtained from exact enumeration naturally contain overlapping regions, which correspond to the hinges of the inter-domain bending motion. The performance of the algorithm is demonstrated on several proteins. © 2015 Wiley Periodicals, Inc.
[A case of rigid spine syndrome with rimmed vacuole].
Onodera, O; Yamazaki, M; Atsumi, T; Miyatake, T; Izumi, T
1990-05-01
A case of rigid spine syndrome associated with rimmed vacuoles in muscle biopsy is reported. A 36-year-old man was admitted to our hospital because of gait disturbance and limited mortality of the spine. His family was free from any neuromuscular disorders. He was born in normal pregnancy and delivery. His physical development was normal. At age 7, he was unable to run fast. At age 36, he had right hemiparesis and dysarthria. He was diagnosed as cerebral infarction of the left basal ganglia by brain CT. Neurological examination revealed moderate proximal dominant muscular atrophy and weakness. His spine was straight, showing loss of physiological cervical and lumbar lordosis. The neck flexion was limited but the extension was full. And he had contracture of bilateral ankle joint. Laboratory findings were all normal. The electrocardiogram showed negative T wave in V4, V5 and QT interval elongation. The echocardiogram showed diffuse decrease of ventricular wall motion. Respiratory function test revealed decrease of vital capacity. Arterial blood gases on room air showed that the PaO2 and PaCO2 were 70 mmHg and 49 mmHg, respectively. The findings of electromyogram were compatible with myopathic change. Biopsy specimen of the biceps brachii muscle showed marked variation in fiber size, type 1 fiber predominancy and atrophy, and type 2B fiber deficiency. Numerous rimmed vaculoes were found in the same muscle. Four cases of the rigid spine syndrome with rimmed vacuoles have been described. Among them, three patients died in young ages and two suffered from constrictive respiratory failure. In rigid spine syndrome with rimmed vacuole formation, the cardiac and respiratory problems must be taken account intensively.
Gaussian Curvature as an Identifier of Shell Rigidity
Harutyunyan, Davit
2017-11-01
In the paper we deal with shells with non-zero Gaussian curvature. We derive sharp Korn's first (linear geometric rigidity estimate) and second inequalities on that kind of shell for zero or periodic Dirichlet, Neumann, and Robin type boundary conditions. We prove that if the Gaussian curvature is positive, then the optimal constant in the first Korn inequality scales like h, and if the Gaussian curvature is negative, then the Korn constant scales like h 4/3, where h is the thickness of the shell. These results have a classical flavour in continuum mechanics, in particular shell theory. The Korn first inequalities are the linear version of the famous geometric rigidity estimate by Friesecke et al. for plates in Arch Ration Mech Anal 180(2):183-236, 2006 (where they show that the Korn constant in the nonlinear Korn's first inequality scales like h 2), extended to shells with nonzero curvature. We also recover the uniform Korn-Poincaré inequality proven for "boundary-less" shells by Lewicka and Müller in Annales de l'Institute Henri Poincare (C) Non Linear Anal 28(3):443-469, 2011 in the setting of our problem. The new estimates can also be applied to find the scaling law for the critical buckling load of the shell under in-plane loads as well as to derive energy scaling laws in the pre-buckled regime. The exponents 1 and 4/3 in the present work appear for the first time in any sharp geometric rigidity estimate.
Nonlinear dynamic behavior of microscopic bubbles near a rigid wall
Suslov, Sergey A.; Ooi, Andrew; Manasseh, Richard
2012-06-01
The nonlinear dynamic behavior of microscopic bubbles near a rigid wall is investigated. Oscillations are driven by the ultrasonic pressure field that arises in various biomedical applications such as ultrasound imaging or targeted drug delivery. It is known that, when bubbles approach a blood-vessel wall, their linear dynamic response is modified. This modification may be very useful for real-time detection of bubbles that have found targets; in future therapeutic technologies, it may be useful for controlled release of medical agents encapsulating microbubbles. In this paper, the nonlinear response of microbubbles near a wall is studied. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of a rigid wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium, and a bubble near a rigid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period-tripling and -quadrupling transition. The parametric bifurcation maps are obtained as functions of nondimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field, and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses. Thus, a
A generic detailed rigid-body lumbar spine model
DEFF Research Database (Denmark)
De Zee, Mark; Hansen, Lone; Wong, Christian
2007-01-01
the literature. The work resulted in a detailed lumbar spine model with seven rigid segments with 18 degrees-of-freedom and 154 muscles. The model is able to produce a maximum extension moment of 238 Nm around L5/S1. Moreover, a comparison was made with in vivo intradiscal pressure measurements of the L4-5 disc...... available from the literature. The model is based on inverse dynamics, where the redundancy problem is solved using optimization in order to compute the individual muscle forces and joint reactions. With the presented model it is possible to investigate a range of research questions, because the model...
Dynamic phase separation of fluid membranes with rigid inclusions.
Weikl, Thomas R
2002-12-01
Membrane shape fluctuations induce attractive interactions between rigid inclusions. Previous analytical studies showed that the fluctuation-induced pair interactions are rather small compared to thermal energies, but also that multibody interactions cannot be neglected. In this paper, it is shown numerically that shape fluctuations indeed lead to the dynamic separation of the membrane into phases with different inclusion concentrations. The tendency of lateral phase separation strongly increases with the inclusion size. Large inclusions aggregate at very small inclusion concentrations and for relatively small values of the inclusions' elastic modulus.
Centrifuge modelling of rigid piles in soft clay
DEFF Research Database (Denmark)
Klinkvort, R.T.; Poder, M.; Truong, P.
2016-01-01
of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...... within the clay sample by carrying out the experiments at different g fields. The findings suggest that the normalised shape of the p-y curves can be predicted within a sufficient accuracy using the current methodology but that the ultimate lat-eral resistance is underestimated at shallow depths...
Spectral rigidity of vehicular streams (random matrix theory approach)
Energy Technology Data Exchange (ETDEWEB)
Krbalek, Milan [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague (Czech Republic); Seba, Petr [Doppler Institute for Mathematical Physics and Applied Mathematics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague (Czech Republic)
2009-08-28
Using a method originally developed for the random matrix theory, we derive an approximate mathematical formula for the number variance {delta}{sub N}(L) describing the rigidity of particle ensembles with a power-law repulsion. The resulting relation is compared with the relevant statistics of the single-vehicle data measured on the Dutch freeway A9. The detected value of the inverse temperature {beta}, which can be identified as a coefficient of the mental strain of the car drivers, is then discussed in detail with the relation to the traffic density {rho} and flow J.
Control of the rigid body and dynamics with symmetry
Lum, Kai-Yew
This dissertation explores various problems in the control of the rigid body and related dynamical systems with symmetry, utilizing various modeling approaches and control techniques. We first derive a control law that asymptotically stabilizes an unbalanced top to the sleeping motion. We rewrite the classical Euler-Poisson equations by projecting the phase space onto IRsp5. The control law is based on the Hamilton-Jacobi-Bellman theory with zero dynamics and partial stability. Lyapunov techniques are used in the analysis. Next, the control of rotor imbalance with magnetic bearings is considered in the adaptive virtual autobalancing and adaptive autocentering approaches. We derive single-plane and two-plane balancing control algorithms that provide asymptotic estimates of the rotor imbalance, and that guarantee consistent performance under varying spin rate. These algorithms are based on emulation of the mechanical autobalancer. We discuss the theory based on linear analysis, and simulation and experimental results. We go on to investigate symmetry properties associated with mechanical control systems and certain nonlinear control systems. First, we generalize the classical Serret-Andoyer transformation for the free rigid body to left-invariant, hyperregular Hamiltonian systems on Tsp*SO(3), employing the notion of symplectic (Marsden-Weinstein) reduction. We then apply this result to the controlled rigid body, and show that for Hamiltonian controls that preserve the rigid body structure, the generalized Serret-Andoyer transformation yields a two dimensional representation of the closed-loop motion in canonical form. Applications to the stability analysis of relative equilibria and numerical integration are also discussed. Finally, we apply the concept of reduction to certain regulation problems on smooth manifolds. Following the works of Van der Schaft (1981) and Grizzle and Marcus (1985), we show that an output feedback regulation problem possessing certain
Symmetry and Reduction for Coordinated Rigid Body Networks
Hanszligmann, H; Smith, T R
2004-01-01
Motivated by interest in the collective behavior of autonomous agents, we study networks of rigid bodies and the problem of coordinated orientation and position across the group. Our main result is the reduction of the networked system in the case that individuals are coupled by control inputs that depend only on relative configuration. We use reduction theory based on semi-direct products; this yields flat Poisson spaces which enable efficient formulation of control laws. In the second part of the paper, we apply the reduction results to particular choices of kinetic energy and prove stability of coordinated behaviors.
Rigid supersymmetry from conformal supergravity in five dimensions
Energy Technology Data Exchange (ETDEWEB)
Pini, Alessandro [Department of Physics, Universidad de Oviedo, Avda. Calvo Sotelo 18, 33007, Oviedo (Spain); Centre for Research in String Theory, School of Physics, Queen Mary University of London,Mile End Road, London, E1 4NS (United Kingdom); Rodriguez-Gomez, Diego; Schmude, Johannes [Department of Physics, Universidad de Oviedo, Avda. Calvo Sotelo 18, 33007, Oviedo (Spain)
2015-09-17
We study the rigid limit of 5d conformal supergravity with minimal supersymmetry on Riemannian manifolds. The necessary and sufficient condition for the existence of a solution is the existence of a conformal Killing vector. Whenever a certain SU(2) curvature becomes abelian the backgrounds define a transversally holomorphic foliation. Subsequently we turn to the question under which circumstances these backgrounds admit a kinetic Yang-Mills term in the action of a vector multiplet. Here we find that the conformal Killing vector has to be Killing. We supplement the discussion with various appendices.
The market for large rigid haul trucks in surface mining
Energy Technology Data Exchange (ETDEWEB)
Gilewicz, P.
2002-04-15
Originally published in 2001 this updated report provides a definition of the market for large rigid haulers in surface mining. The analysis covers changes to the mining market segments buying these machines including the gains made by coal producers, retrenchment in copper mining, the consolidation taking place among gold mining companies, and the expansion of iron ore producers in Australia and Brazil. It includes a detailed accounting of 2001 truck shipments, and an analysis of trends in the Ultra-truck segment. It concludes with a revised forecast for shipments through 2006. 12 charts, 56 tabs., 2 apps.
The bottom of the universe: Flat earth science in the Age of Encounter.
Allegro, James J
2017-03-01
This essay challenges the dominance of the spherical earth model in fifteenth- and early-sixteenth-century Western European thought. It examines parallel strains of Latin and vernacular writing that cast doubt on the existence of the southern hemisphere. Three factors shaped the alternate accounts of the earth as a plane and disk put forward by these sources: (1) the unsettling effects of maritime expansion on scientific thought; (2) the revival of interest in early Christian criticism of the spherical earth; and (3) a rigid empirical stance toward entities too large to observe in their entirety, including the earth. Criticism of the spherical earth model faded in the decades after Magellan's crew returned from circuiting the earth in 1522.
Compressibility and planetary interiors. [solid core theory applicable to Earth and Venus
Bullen, K. E.
1972-01-01
Important confirmations that the Earth's inner core is solid have recently come from analyses of records of free Earth oscillations and from the apparent detection of the seismic phase PKJKP. Corresponding support is given to the theory which supplied the primary evidence for rigidity in the inner core. This theory requires the incompressibility and its gradient with respect to the pressure p to vary fairly smoothly with p inside planets, and supplies a potent restriction on the allowable variations of particular physical properties inside parts of planetary interiors. The theory is at present principally applicable to the Earth and Venus. The paper reviews some of the principal implications.
Reopening modes of a collapsed elasto-rigid channel
Ducloué, Lucie; Thompson, Alice B; Juel, Anne
2016-01-01
Motivated by the reopening mechanics of strongly collapsed airways, we study the steady propagation of an air finger through a collapsed oil-filled channel with a single compliant wall. In a previous study using fully-compliant elastic tubes, a `pointed' air finger was found to propagate at high speed and low pressure, which may enable rapid reopening of highly collapsed airways with minimal tissue damage (Heap & Juel 2008). In this paper, we identify the selection mechanism of that pointed finger, which remained unexplained, by conducting an experimental study in a rigid rectangular Hele-Shaw channel with an elastic top boundary. The constitutive behaviour of this elasto-rigid channel is broadly similar to that of an elastic tube, but unlike the tube the channel's cross-section adopts self-similar shapes from the undeformed state to the point of first near wall contact. The simplification of the vessel geometry enables the systematic investigation of the reopening dynamics in terms of initial collapse. W...
Synthesis of rigid polyurethane foams from phosphorylated biopolyols.
de Haro, Juan Carlos; López-Pedrajas, Daniel; Pérez, Ángel; Rodríguez, Juan Francisco; Carmona, Manuel
2017-08-18
Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H3PO4. The formation of phosphate polyesters was confirmed by FT-IR and 31P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57 wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.
Collisions of Constrained Rigid Body Systems with Friction
Directory of Open Access Journals (Sweden)
Haijun Shen
1998-01-01
Full Text Available A new approach is developed for the general collision problem of two rigid body systems with constraints (e.g., articulated systems, such as massy linkages in which the relative tangential velocity at the point of contact and the associated friction force can change direction during the collision. This is beyond the framework of conventional methods, which can give significant and very obvious errors for this problem, and both extends and consolidates recent work. A new parameterization and theory characterize if, when and how the relative tangential velocity changes direction during contact. Elastic and dissipative phenomena and different values for static and kinetic friction coefficients are included. The method is based on the explicitly physical analysis of events at the point of contact. Using this method, Example 1 resolves (and corrects a paradox (in the literature of the collision of a double pendulum with the ground. The method fundamentally subsumes other recent models and the collision of rigid bodies; it yields the same results as conventional methods when they would apply (Example 2. The new method reformulates and extends recent approaches in a completely physical context.
Rigid motion artifact reduction in CT using frequency domain analysis.
Zhang, Yuan; Zhang, Liyi; Sun, Yunshan
2017-01-01
It is often unrealistic to assume that the subject remains stationary during a computed tomography (CT) imaging scan. A patient rigid motion can be decomposed into a translation and a rotation around an origin. How to minimize the motion impact on image quality is important. To eliminate artifacts caused by patient rigid motion during a CT scan, this study investigated a new method based on frequency domain analysis to estimate and compensate motion impact. Motion parameters was first determined by the magnitude correlation of projections in frequency domain. Then, the estimated parameters were applied to compensate for the motion effects in the reconstruction process. Finally, this method was extended to helical CT. In fan-beam CT experiments, the simulation results showed that the proposed method was more accurate and faster on the performance of motion estimation than using Helgason-Ludwig consistency condition method (HLCC). Furthermore, the reconstructed images on both simulated and human head experiments indicated that the proposed method yielded superior results in artifact reduction. The proposed method is a new tool for patient motion compensation, with a potential for practical application. It is not only applicable to motion correction in fan-beam CT imaging, but also to helical CT.
Loading on a Rigid Target from Close Proximity Underwater Explosions
Directory of Open Access Journals (Sweden)
Mark Riley
2012-01-01
Full Text Available The study describes recent simulation results for underwater explosions in close-proximity to rigid targets. Simulations are performed using Chinook, an Eulerian computational fluid dynamics (CFD code. Predicted target loadings are compared with measurements taken from a series of experiments conducted under an international collaboration between Canada, The Netherlands, and Sweden. The simulations of the rigid target tests focused on the modelling of gas bubble collapse and water jetting behaviour. Both two-dimensional and three-dimensional simulations were performed. It was found that the two-dimensional analyses produced good bubble periods and reasonable impulse loading compared to experimental data. The time of arrival of the bubble collapse and water jetting were found to be very mesh dependent and refining the mesh did not always produce better results. The two-dimensional approach provides a good initial understanding of the problem for a reasonable computational effort. The three-dimensional simulations were found to produce improved impulse predictions. The numerical gas bubble radii time histories are also compared to empirical time histories.
Polynomials for crystal frameworks and the rigid unit mode spectrum
Power, S. C.
2014-01-01
To each discrete translationally periodic bar-joint framework in , we associate a matrix-valued function defined on the d-torus. The rigid unit mode (RUM) spectrum of is defined in terms of the multi-phases of phase-periodic infinitesimal flexes and is shown to correspond to the singular points of the function and also to the set of wavevectors of harmonic excitations which have vanishing energy in the long wavelength limit. To a crystal framework in Maxwell counting equilibrium, which corresponds to being square, the determinant of gives rise to a unique multi-variable polynomial . For ideal zeolites, the algebraic variety of zeros of on the d-torus coincides with the RUM spectrum. The matrix function is related to other aspects of idealized framework rigidity and flexibility, and in particular leads to an explicit formula for the number of supercell-periodic floppy modes. In the case of certain zeolite frameworks in dimensions two and three, direct proofs are given to show the maximal floppy mode property (order N). In particular, this is the case for the cubic symmetry sodalite framework and some other idealized zeolites. PMID:24379422
Dynamics of parallel robots from rigid bodies to flexible elements
Briot, Sébastien
2015-01-01
This book starts with a short recapitulation on basic concepts, common to any types of robots (serial, tree structure, parallel, etc.), that are also necessary for computation of the dynamic models of parallel robots. Then, as dynamics requires the use of geometry and kinematics, the general equations of geometric and kinematic models of parallel robots are given. After, it is explained that parallel robot dynamic models can be obtained by decomposing the real robot into two virtual systems: a tree-structure robot (equivalent to the robot legs for which all joints would be actuated) plus a free body corresponding to the platform. Thus, the dynamics of rigid tree-structure robots is analyzed and algorithms to obtain their dynamic models in the most compact form are given. The dynamic model of the real rigid parallel robot is obtained by closing the loops through the use of the Lagrange multipliers. The problem of the dynamic model degeneracy near singularities is treated and optimal trajectory planning for cro...
Origami-Inspired Folding of Thick, Rigid Panels
Trease, Brian P.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Zirbel, Shannon; Howell, Larry; Lang, Robert
2014-01-01
To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design. Three origami-inspired folding techniques (flasher, square twist, and map fold) were created with rigid panels and hinges. Hinge components are added to the model to enable folding of thick, rigid materials. Origami models are created assuming zero (or near zero) thickness. When a material with finite thickness is used, the panels are required to bend around an increasingly thick fold as they move away from the center of the model. The two approaches for dealing with material thickness are to use membrane hinges to connect the panels, or to add panel hinges, or hinges of the same thickness, at an appropriate width to enable folding.
Statistics of admixture distribution in flows through rigid foams
Denissenko, Petr; Le Fur, Pierre; Vlaskamp, Jozef; Williams, Mark; Fan, Xiaolei; Lapkin, Alexei
2014-11-01
Diffusion and dispersion of admixture in flows through rigid foams need to be accounted for when modelling catalytic reactions on the foam surface. We study diffusion of admixture and scaling exponents of admixture concentration both experimentally and by numerical simulations. A liquid admixture was continuously released from a point source at the upstream boundary of a block of rigid SiC foam. Foam thickness was varied from 20 to 80 average pore sizes. A flow with Re of up to 300 based on the pore size was imposed by a progressive cavity pump. The distribution of the tracer at the exit from the foam was measured using LIF and the concentration moments have been calculated. Numerical simulation of the flow in laminar regime has been performed within OpenFoam for the Re from 1 to 100. Geometry of the sample was acquired by Micro Computed Tomography scanning of the actual foam sample. A steady-state SIMPLE method was used to solve the incompressible steady flow in the volume of 20 × 20 × 40 average pore sizes. Diffusion and dispersion of passive scalar has been studied by following individual streamlines. Results are interpreted in terms of mixing, heat transfer, and selectivity of catalytic reactions at the foam surface. This Research is supported by European Commission under the 7th Framework Program.
Computer-aided rigid choledochoscopy lithotripsy for hepatolithiasis.
Fang, Chi-Hua; Li, Gang; Wang, Ping; Fan, Ying-Fang; Zhong, Shi-Zhen
2015-05-01
Hepatolithiasis is challenging for surgeons to treat especially in patients with previous hepatobiliary surgery. The aim of the study was to report our experience of rigid choledochoscopy lithotripsy in targeted treatment of hepatolithiasis under the guidance of a medical image three-dimensional visualization system, which we developed and patented (software copyright no: 2008SR18 798) by comparing it with hepatectomy without a three-dimensional (3D) reconstruction technique. Between December 2007 and March 2013, 64 patients underwent rigid choledochoscopy lithotripsy based on 3D visualization technology conducted by a medical image three-dimensional visualization system for hepatolithiasis (group A). During the same period, 61 patients with hepatolithiasis were selected for hepatectomy (group B). Comparative analysis was made of demographic and perioperative characteristics of the two groups. 3D visualization was instructive for surgeons on how the stones were distributed and what the spatial relationship was between stones and the intrahepatic vascular system. Compared with patients in group B, those in group A had a significantly lower intermediate residual stone rate, a faster operating time, a lower intraoperative blood loss and intraoperative blood transfusion, a shorter postoperative hospital stay, less postoperative complications, and more liver function reserved (P Copyright © 2015 Elsevier Inc. All rights reserved.
Rigidity-induced scale invariance in polymer ejection from capsid
Linna, R. P.; Suhonen, P. M.; Piili, J.
2017-11-01
While the dynamics of a fully flexible polymer ejecting a capsid through a nanopore has been extensively studied, the ejection dynamics of semiflexible polymers has not been properly characterized. Here we report results from simulations of ejection dynamics of semiflexible polymers ejecting from spherical capsids. Ejections start from strongly confined polymer conformations of constant initial monomer density. We find that, unlike for fully flexible polymers, for semiflexible polymers the force measured at the pore does not show a direct relation to the instantaneous ejection velocity. The cumulative waiting time t (s ) , that is, the time at which a monomer s exits the capsid the last time, shows a clear change when increasing the polymer rigidity κ . The major part of an ejecting polymer is driven out of the capsid by internal pressure. At the final stage the polymer escapes the capsid by diffusion. For the driven part there is a crossover from essentially exponential growth of t with s of the fully flexible polymers to a scale-invariant form. In addition, a clear dependence of t on polymer length N0 was found. These findings combined give the dependence t (s ) ∝N00.55s1.33 for the strongly rigid polymers. This crossover in dynamics where κ acts as a control parameter is reminiscent of a phase transition. This analogy is further enhanced by our finding a perfect data collapse of t for polymers of different N0 and any constant κ .
Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation
Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.
2012-01-01
Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.
Modyfication of the Rigid Polyurethane-Polyisocyanurate Foams
Directory of Open Access Journals (Sweden)
Bogusław Czupryński
2014-01-01
Full Text Available The effect of polyethylene glycol 1500 on physicomechanical properties of rigid polyurethane-polyisocyanurate (PUR-PIR foams has been studied. It was found that application of polyethylene glycol 1500 for synthesis of foams in amount from 0% to 20% w/w had an effect on reduction of brittleness and softening point, while the greater the increase in compressive strength the higher its content in foam composition was. Wastes from production of these foams were ground and subjected to glycolysis in diethylene glycol with the addition of ethanolamine and zinc stearate. Liquid brown products were obtained. Properties of the resulting products were defined in order to determine their suitability for synthesis of new foams. It was found that glycolysate 6 was the most suitable for reuse and its application in different amounts allowed us to prepare 4 new foams (nos. 25, 26, 27, and 28. Properties of foams prepared in this manner were determined and, on their basis, the suitability of glycolysates for production of rigid PUR-PIR foams was evaluated.
A Soft Gripper with Rigidity Tunable Elastomer Strips as Ligaments.
Nasab, Amir Mohammadi; Sabzehzar, Amin; Tatari, Milad; Majidi, Carmel; Shan, Wanliang
2017-12-01
Like their natural counterparts, soft bioinspired robots capable of actively tuning their mechanical rigidity can rapidly transition between a broad range of motor tasks-from lifting heavy loads to dexterous manipulation of delicate objects. Reversible rigidity tuning also enables soft robot actuators to reroute their internal loading and alter their mode of deformation in response to intrinsic activation. In this study, we demonstrate this principle with a three-fingered pneumatic gripper that contains "programmable" ligaments that change stiffness when activated with electrical current. The ligaments are composed of a conductive, thermoplastic elastomer composite that reversibly softens under resistive heating. Depending on which ligaments are activated, the gripper will bend inward to pick up an object, bend laterally to twist it, and bend outward to release it. All of the gripper motions are generated with a single pneumatic source of pressure. An activation-deactivation cycle can be completed within 15 s. The ability to incorporate electrically programmable ligaments in a pneumatic or hydraulic actuator has the potential to enhance versatility and reduce dependency on tubing and valves.
Rigid spherical particles in highly turbulent Taylor-Couette flow
Bakhuis, Dennis; Verschoof, Ruben A.; Mathai, Varghese; Huisman, Sander G.; Lohse, Detlef; Sun, Chao
2016-11-01
Many industrial and maritime processes are subject to enormous frictional losses. Reducing these losses even slightly will already lead to large financial and environmental benefits. The understanding of the underlying physical mechanism of frictional drag reduction is still limited, for example, in bubbly drag reduction there is an ongoing debate whether deformability and bubble size are the key parameters. In this experimental study we report high precision torque measurements using rigid non-deformable spherical particles in highly turbulent Taylor-Couette flow with Reynolds numbers up to 2 ×106 . The particles are made of polystyrene with an average density of 1.036 g cm-3 and three different diameters: 8mm, 4mm, and 1.5mm. Particle volume fractions of up to 6% were used. By varying the particle diameter, density ratio of the particles and the working fluid, and volume fraction of the particles, the effect on the torque is compared to the single phase case. These systematic measurements show that adding rigid spherical particles only results in very minor drag reduction. This work is financially supported by Netherlands Organisation for Scientific Research (NWO) by VIDI Grant Number 13477.
Horizontal fall arrest systems: rigid systems vs. flexible line systems.
Lough, David
2004-09-01
There are many types of flexible and rigid systems on the market, both permanent and temporary. This article does not mean to encompass all possible systems or hazards and only intends to give an outline of what at a minimum should be examined to make an educated purchasing decision. In many instances, the buyer will use the same type of horizontal system for all situations. This is a good idea in some cases because it will reduce the need for training on a number of different systems, reduce system compatibility issues, and may reduce costs for installation, supply, and maintenance. This may not be the best idea if the hazard areas differ a great deal; as we have illustrated, one system may not function for all areas and tasks. The rigid system is typically the best solution simply based on the fact the worker won't fall as far as when he is connected to a flexible system, because of the elimination of any dynamic sag and horizontal energy absorber deployment. In any case, where you stop the worker from falling farther, you decrease the chance there may be an incident where the worker is injured. From a cost standpoint, flexible fall arrest systems typically are cheapest. In the end, safety professionals must balance the cost and effectiveness of the system to prevent an injury.
A randomized clinical trial of treatment for lumbar segmental rigidity.
Mayer, Tom G; Gatchel, Robert J; Keeley, Janice; McGeary, Don; Dersh, Jeffrey; Anagnostis, Christopher
2004-10-15
A randomized single-blind clinical trial of facet injections plus exercise, versus exercise alone, in chronic disabling work-related lumbar spinal disorders (CDWRLSD), accompanied by pilot interrater reliability and facet syndrome prevalence studies. To systematically investigate the use of facet injections as an adjunct to supervised lumbar stretching exercises in regaining lumbar range of motion (ROM) following prolonged deconditioning after work-related lumbar injuries. To assess interrater reliability of visual assessment of segmental rigidity (SR), and to evaluate the prevalence of facet syndrome in cases of lumbar SR. Corticosteroid joint injections have often been used to reduce musculoskeletal inflammation to facilitate joint mobilization in the presence of degenerative arthritis. Lumbar segmental rigidity is a recently described entity usually associated with painful chronic spinal disorders and postoperative spine surgery. Previous work has shown that SR and lumbar ROM improves with a brief intervention consisting of facet injections followed by specific stretching exercises. No systematic study has investigated the potential benefits of a combination of facet injections and exercise over supervised exercises alone to treat lumbar SR. Similarly, no study has assessed the association between SR and the facet syndrome. From a group of consecutive patients (n = 421) with CDWRLSD referred for tertiary rehabilitation between November 1999 and January 2001, 70 were noted to have SR on intake physical examination. The first part of this study assessed interrater reliability for detecting SR, and intrarater reliability for 3-segment true lumbar ROM measurements. Patients randomly assigned to participate in supervised stretching exercises with the addition of fluoroscopically guided bilateral facet injections at the involved levels (Group A, n = 36) also underwent facet syndrome prevalence assessment at the time of injection. They were compared to a randomly
Knezovich, F. M.
1976-01-01
A modular structured system of computer programs is presented utilizing earth and ocean dynamical data keyed to finitely defined parameters. The model is an assemblage of mathematical algorithms with an inherent capability of maturation with progressive improvements in observational data frequencies, accuracies and scopes. The Eom in its present state is a first-order approach to a geophysical model of the earth's dynamics.
Introducing Earth's Orbital Eccentricity
Oostra, Benjamin
2015-01-01
Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…
Blok, Vincent
2016-01-01
Quentin Meillassoux's call for realism is a call for a new interest in the Earth as un-correlated being in philosophy. Unlike Meillassoux, Martin Heidegger has not been criticized for being a correlationist. To the contrary, his concept of the Earth has to be understood as un-correlated being, as it
Structure and properties of a new rigid tripodal oxime ligand
Premužić, Dejan; Filarowski, Aleksander; Hołyńska, Małgorzata
2017-05-01
Synthesis and properties of a new rigid tripodal oxime ligand are reported. The ligand is a derivative of phloroglucine with three carboxime arms alternate with hydroxyl groups and three intramolecular Osbnd H⋯N hydrogen bonds. Intermolecular Osbnd H⋯O hydrogen bonds result in formation of a characteristic three-dimensional network. The structure of the compound is further analyzed and confirmed by NMR, IR and MS-techniques. DFT calculations were employed to accomplish the analysis of both the hydrogen bonding and the conformational state of the ligand under study. Additionally, the study addresses the way the conformational state and metal-replacement influence the tautomeric equilibrium OH⋯N ⇆ O-⋯+HN in the studied moieties.
Confining rigid balls by mimicking quadrupole ion trapping
Fan, Wenkai; Du, Li; Wang, Sihui; Zhou, Huijun
2017-11-01
The rotating saddle not only is an interesting system that is able to trap a ball near its saddle point, but can also intuitively illustrate the operating principles of quadrupole ion traps in modern physics. Unlike the conventional models based on the mass-point approximation, we study the stability of a ball in a rotating-saddle trap using rigid-body dynamics. The stabilization condition of the system is theoretically derived and subsequently verified by experiments. The results are compared with the previous mass-point model, giving large discrepancy as the curvature of the ball is comparable to that of the saddle. We also point out that the spin angular velocity of the ball is analogous to the cyclotron frequency of ions in an external magnetic field utilized in many prevailing ion-trapping schemes.
Dynamics of Rigid Bodies and Flexible Beam Structures
DEFF Research Database (Denmark)
Nielsen, Martin Bjerre
of rigid bodies and flexible beam structures with emphasis on the rotational motion. The first part deals with motion in a rotating frame of reference. A novel approach where the equations of motion are formulated in a hybrid state-space in terms of local displacements and global velocities is presented...... quaternion parameters or nine convected base vector components. In both cases, the equations of motion are obtained via Hamilton’s equations by including the kinematic constraints associated with the redundant rotation description by means of Lagrange multipliers. A special feature of the formulation...... of the global components of the position vectors and associated convected base vectors for the element nodes. The kinematics is expressed in a homogeneous quadratic form and the constitutive stiffness is derived from complementary energy of a set of equilibrium modes, each representing a state of constant...
Percutaneous antegrade ureteric stent removal using a rigid alligator forceps.
LENUS (Irish Health Repository)
Given, M F
2008-12-01
To evaluate the safety and efficacy of percutaneous antegrade ureteric stent removal using a rigid alligator forceps. Twenty patients were included in our study. Indications for ureteric stent insertion included stone disease (n = 7), malignancy (n = 8) and transplant anastomotic strictures (n = 5). Stent retrieval was carried out for proximal stent placement\\/migration in seven patients and encrustation in the remaining 13. Twenty-two stents were successfully retrieved in 20 patients. There was one technical failure (5%). There were no major complications. We had four minor complications, which included nephrostomy site pain (n = 2), periprocedural sepsis (n = 1) and a small urinoma (n = 1). All patients settled with conservative management. Percutaneous radiologically guided antegrade ureteric stent removal with an alligator forceps is safe and effective, particularly when initial surgical removal has failed.
Controlling elastic waves with small phononic crystals containing rigid inclusions
Peng, Pai
2014-05-01
We show that a two-dimensional elastic phononic crystal comprising rigid cylinders in a solid matrix possesses a large complete band gap below a cut-off frequency. A mechanical model reveals that the band gap is induced by negative effective mass density, which is affirmed by an effective medium theory based on field averaging. We demonstrate, by two examples, that such elastic phononic crystals can be utilized to design small devices to control low-frequency elastic waves. One example is a waveguide made of a two-layer anisotropic elastic phononic crystal, which can guide and bend elastic waves with wavelengths much larger than the size of the waveguide. The other example is the enhanced elastic transmission of a single-layer elastic phononic crystal loaded with solid inclusions. The effective mass density and reciprocal of the modulus of the single-layer elastic phononic crystal are simultaneously near zero. © CopyrightEPLA, 2014.
Testing the disturbed zone around a rigid inclusion in salt
Energy Technology Data Exchange (ETDEWEB)
Knowles, M.K.; Borns, D.; Fredrich, J.; Holcomb, D.; Price, R.; Zeuch, D. [Sandia National Labs., Albuquerque, NM (United States); Dale, T.; Van Pelt, R.S. [INTERA, Inc., Austin, TX (United States)
1996-12-01
Deformational processes within a zone of rock surrounding excavations in salt result in alteration of the geophysical and hydrologic properties as compared to the undisturbed condition. The disturbed rock zone offers little resistance to fluid flow. It is hypothesized that rigid inclusions such as concrete seals will arrest and subsequently reverse the disturbance process and induce healing in the disturbed This experiment gathered in situ data that substantiates this hypothesis. A series of tests was conducted in a volume of rock surrounding concrete seals that were placed in a 1-m borehole approximately eight years ago. Fluid flow measurements, measurements of geophysical parameters of the surrounding rock and petrographic analyses on core samples were performed to characterize the rock. This paper presents the testing methodology and summarizes the data gathered from the field test program.
Non-rigid registration by geometry-constrained diffusion
DEFF Research Database (Denmark)
Andresen, Per Rønsholt; Nielsen, Mads
1999-01-01
Assume that only partial knowledge about a non-rigid registration is given so that certain point, curves, or surfaces in one 3D image map to certain points, curves, or surfaces in another 3D image. We are facing the aperture problem because along the curves and surfaces, point correspondences...... are not given. We will advocate the viewpoint that the aperture and the 3D interpolation problem may be solved simultaneously by finding the simplest displacement field. This is obtained by a geometry-constrained diffusion which yields the simplest displacement field in a precise sense. The point registration...... obtained may be used for growth modelling, shape statistics, or kinematic interpolation. The algorithm applies to geometrical objects of any dimensionality. We may thus keep any number of fiducial points, curves, and/or surfaces fixed while finding the simplest registration. Examples of inferred point...
Random Matrix Theory of Rigidity in Soft Matter
Yamanaka, Masanori
2015-06-01
We study the rigidity or softness of soft matter using the characteristic scale of coupling formation developed in random matrix theory. The eigensystems of the timescale-dependent cross-correlation matrix, which are obtained from the time series data of the atomic coordinates of a protein produced by the all-atom molecular dynamics of the solvent, are analyzed. As an example, we present a result for a protein lysozyme, PDBID:1AKI. We find that there are at least three different time scales involved in the coupling formation of correlated sectors of atoms and at least two different time scales for the size of the correlated sectors. These five time scales coexist simultaneously. We compare the results with those of the normal mode analysis and find a crossover of the distribution of the dominant vibrational components.
Asynchronous oscillations of rigid rods drive viscous fluid to swirl
Hayashi, Rintaro; Takagi, Daisuke
2017-12-01
We present a minimal system for generating flow at low Reynolds number by oscillating a pair of rigid rods in silicone oil. Experiments show that oscillating them in phase produces no net flow, but a phase difference alone can generate rich flow fields. Tracer particles follow complex trajectory patterns consisting of small orbital movements every cycle and then drifting or swirling in larger regions after many cycles. Observations are consistent with simulations performed using the method of regularized Stokeslets, which reveal complex three-dimensional flow structures emerging from simple oscillatory actuation. Our findings reveal the basic underlying flow structure around oscillatory protrusions such as hairs and legs as commonly featured on living and nonliving bodies.
Inertial and viscoelastic forces on rigid colloids in microfluidic channels.
Howard, Michael P; Panagiotopoulos, Athanassios Z; Nikoubashman, Arash
2015-06-14
We perform hybrid molecular dynamics simulations to study the flow behavior of rigid colloids dispersed in a dilute polymer solution. The underlying Newtonian solvent and the ensuing hydrodynamic interactions are incorporated through multiparticle collision dynamics, while the constituent polymers are modeled as bead-spring chains, maintaining a description consistent with the colloidal nature of our system. We study the cross-stream migration of the solute particles in slit-like channels for various polymer lengths and colloid sizes and find a distinct focusing onto the channel center under specific solvent and flow conditions. To better understand this phenomenon, we systematically measure the effective forces exerted on the colloids. We find that the migration originates from a competition between viscoelastic forces from the polymer solution and hydrodynamically induced inertial forces. Our simulations reveal a significantly stronger fluctuation of the lateral colloid position than expected from thermal motion alone, which originates from the complex interplay between the colloid and polymer chains.
Slip Morphology of Elastic Strips on Frictional Rigid Substrates.
Sano, Tomohiko G; Yamaguchi, Tetsuo; Wada, Hirofumi
2017-04-28
The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which-when the bending elasticity dominates over the effect of gravity-are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and the coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law and find excellent quantitative agreement with simulations and controlled physical experiments. We also discuss the effect of gravity in order to bridge the difference in the qualitative behaviors of stiff strips and flexible strings or ropes. Our study thus complements recent work on elastic rope coiling and takes a significant step towards establishing a unified understanding of how a thin elastic object interacts vertically with a solid surface.
Complexity management theory: motivation for ideological rigidity and social conflict.
Peterson, Jordan B; Flanders, Joseph L
2002-06-01
We are doomed to formulate conceptual structures that are much simpler than the complex phenomena they are attempting to account for. These simple conceptual structures shield us, pragmatically, from real-world complexity, but also fail, frequently, as some aspect of what we did not take into consideration makes itself manifest. The failure of our concepts dysregulates our emotions and generates anxiety, necessarily, as the unconstrained world is challenging and dangerous. Such dysregulation can turn us into rigid, totalitarian dogmatists, as we strive to maintain the structure of our no longer valid beliefs. Alternatively, we can face the underlying complexity of experience, voluntarily, gather new information, and recast and reconfigure the structures that underly our habitable worlds.
Plasma surface modification of rigid contact lenses decreases bacterial adhesion.
Wang, Yingming; Qian, Xuefeng; Zhang, Xiaofeng; Xia, Wei; Zhong, Lei; Sun, Zhengtai; Xia, Jing
2013-11-01
Contact lens safety is an important topic in clinical studies. Corneal infections usually occur because of the use of bacteria-carrying contact lenses. The current study investigated the impact of plasma surface modification on bacterial adherence to rigid contact lenses made of fluorosilicone acrylate materials. Boston XO and XO2 contact lenses were modified using plasma technology (XO-P and XO2-P groups). Untreated lenses were used as controls. Plasma-treated and control lenses were incubated in solutions containing Staphylococcus aureus or Pseudomonas aeruginosa. MTT colorimetry, colony-forming unit counting method, and scanning electron microscopy were used to measure bacterial adhesion. MTT colorimetry measurements showed that the optical density (OD) values of XO-P and XO2-P were significantly lower than those of XO and XO2, respectively, after incubation with S. aureus (P plasma technology in contact lens surface modification.
Osseous adaptation to continuous loading of rigid endosseous implants
Roberts, W. E.; Smith, R. K.; Mozsary, P. G.; Zilberman, Y.; Smith, R. S.
1984-01-01
The effect of loading on etched Ti implants in the femurs of young (3 mo) and adult (6 mo) rabbits is investigated experimentally. The results are presented in photographs, fluorescence and polarization micrographs, radiographs, and drawings and discussed. Implantation is followed by formation of coarse woven bone within 3 d and mature lamellar bone by 6 wks, with nonspecific subperiosteal bony hypertrophy in the young rabbits only. Spring loading at 100 g produces spontaneous spiral-type fractures when applied immediately, but the implants remain rigid when loads are applied after 6-12 wks of healing. The mechanisms of bone formation involved are examined, and the potential of endosseous implants as anchors in orthodontics or dentofacial-orthopedics is confirmed.
Impedances of rigid cylindrical foundations embedded in transversely isotropic soils
Barros, P. L. A.
2006-06-01
A complete formulation and implementation for assessment of the response to dynamic loads of cylindrical rigid structures embedded in transversely isotropic elastic half-spaces is presented. The analysis is performed in the frequency domain and the steady-state structure response is obtained. The method is based on a non-singular version of the indirect boundary element method which uses influence functions, instead of Green's functions, as fundamental solutions. These influence functions are the response of an elastic half-space to distributed, internally applied loads. The proposed method imposes full bonding contact between the foundation and the surrounding soil. Numerical results for displacement (vertical and horizontal) and rotation (twisting and rocking) impedances, showing the influence of the soil anisotropy, are presented. Results for the soil-structure interface tractions and for the displacement field throughout the half-space are also shown.
Rummel, R.
1991-10-01
The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.
A rigid motion correction method for helical computed tomography (CT)
Kim, J.-H.; Nuyts, J.; Kyme, A.; Kuncic, Z.; Fulton, R.
2015-03-01
We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed and the phantom. Motion correction was performed by restoring projection consistency using data from the motion tracking system, and reconstructing with an iterative fully 3D algorithm. Motion correction accuracy was evaluated by comparing reconstructed images with a stationary reference scan. We also investigated the effects on accuracy of tracker sampling rate, measurement jitter, interpolation of tracker measurements, and the synchronization of motion data and CT projections. After optimization of these aspects, motion corrected images corresponded remarkably closely to images of the stationary phantom with correlation and similarity coefficients both above 0.9. We performed a simulation study using volunteer head motion and found similarly that our method is capable of compensating effectively for realistic human head movements. To the best of our knowledge, this is the first practical demonstration of generalized rigid motion correction in helical CT. Its clinical value, which we have yet to explore, may be significant. For example it could reduce the necessity for repeat scans and resource-intensive anesthetic and sedation procedures in patient groups prone to motion, such as young children. It is not only applicable to dedicated CT imaging, but also to hybrid PET/CT and SPECT/CT, where it could also ensure an accurate CT image for lesion localization and attenuation correction of the functional image data.
Rigidity and Fluidity in Living and Nonliving Matter
Lopez, Jorge H.
Many of the standard equilibrium statistical mechanics techniques do not readily apply to non-equilibrium phase transitions such as the fluid-to-disordered solid transition found in repulsive particulate systems. Examples of repulsive particulate systems are sand grains and colloids. The first part of this thesis contributes to methods beyond equilibrium statistical mechanics to ultimately understand the nature of the fluid-to-disordered solid transition, or jamming, from a microscopic basis. In Chapter 2 we revisit the concept of minimal rigidity as applied to frictionless, repulsive soft sphere packings in two dimensions with the introduction of the jamming graph. Minimal rigidity is a purely combinatorial property encoded via Laman's theorem in two dimensions. It constrains the global, average coordination number of the graph, for instance. Minimal rigidity, however, does not address the geometry of local mechanical stability. The jamming graph contains both properties of global mechanical stability at the onset of jamming and local mechanical stability. We demonstrate how jamming graphs can be constructed using local rules via the Henneberg construction such that these graphs are of the constraint percolation type, where percolation is the study of connected structures in disordered networks. We then probe how jamming graphs destabilize, or become fluid-like, by deleting an edge/contact in the graph and computing the resulting rigid cluster distribution. We also uncover a new potentially diverging lengthscale associated with the random deletion of contacts. In Chapter 3 we study several constraint percolation models, such as k-core percolation and counter-balance percolation, on hyperbolic lattices to better understand the role of loops in such models. The constraints in these percolation models incorporate aspects of local mechanical rigidity found in jammed systems. The expectation is that since these models are indeed easier to analyze than the more
Rigid-Plastic Post-Buckling Analysis of Columns and Quadratic Plates
DEFF Research Database (Denmark)
Jönsson, Jeppe
2008-01-01
the compressive load as a function of the transverse displacement. An estimate of the magnitude of the transverse displacement prior to the forming of the collapse mechanism is introduced into the compressive load function, determined by the virtual work equation, thereby revealing a qualified estimate...... yield lines accommodate differential rotations of rigid parts and the area “collapse” yield lines accommodate local area changes of the rigid parts thereby preserving compatibility of the rigid parts of a plate. The approach will be illustrated for rigid plastic column analysis and for a quadratic plate...
Earth's structure and evolution inferred from topography, gravity, and seismicity.
Watkinson, A. J.; Menard, J.; Patton, R. L.
2016-12-01
Earth's wavelength-dependent response to loading, reflected in observed topography, gravity, and seismicity, can be interpreted in terms of a stack of layers under the assumption of transverse isotropy. The theory of plate tectonics holds that the outermost layers of this stack are mobile, produced at oceanic ridges, and consumed at subduction zones. Their toroidal motions are generally consistent with those of several rigid bodies, except in the world's active mountain belts where strains are partitioned and preserved in tectonite fabrics. Even portions of the oceanic lithosphere exhibit non-rigid behavior. Earth's gravity-topography cross-spectrum exhibits notable variations in signal amplitude and character at spherical harmonic degrees l=13, 116, 416, and 1389. Corresponding Cartesian wavelengths are approximately equal to the respective thicknesses of Earth's mantle, continental mantle lithosphere, oceanic thermal lithosphere, and continental crust, all known from seismology. Regional variations in seismic moment release with depth, derived from the global Centroid Moment Tensor catalog, are also evident in the crust and mantle lithosphere. Combined, these observations provide powerful constraints for the structure and evolution of the crust, mantle lithosphere, and mantle as a whole. All that is required is a dynamically consistent mechanism relating wavelength to layer thickness and shear-strain localization. A statistically-invariant 'diharmonic' relation exhibiting these properties appears as the leading order approximation to toroidal motions on a self-gravitating body of differential grade-2 material. We use this relation, specifically its predictions of weakness and rigidity, and of folding and shear banding response as a function of wavelength-to-thickness ratio, to interpret Earth's gravity, topography, and seismicity in four-dimensions. We find the mantle lithosphere to be about 255-km thick beneath the Himalaya and the Andes, and the long
A Numerical Experiment to Test the Influence of the Uncertainty of Earth Model on Nutation
Huang, C. L.; Zhang, M.
2014-12-01
From an infinite set of coupled ordinary differential equations that govern the infinitesimal elastic-gravitational oscillations of a rotating, slightly elliptical Earth, as well as a set of boundary conditions on displacement vector, stress tensor and gravity potential, the theoretical nutation model of non-rigid earth can be numerically obtained. In these differential equations and the boundary conditions, the distributions of density and elastic (Lame) parameters interior the Earth are key parameters and are usually input from 1D earth model like PREM. However, the influence of the uncertainty of a given earth model on nutation has never been checked. In this work, we made a numerical experiment to test it, and some primary results will be presented.
,
2010-01-01
For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!
Earth Science Informatics - Overview
Ramapriyan, H. K.
2017-01-01
Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.The talk will present an overview of current efforts in ESI, the role members of IEEE GRSS play, and discuss
Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi
2014-01-09
A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome includes the age of the Earth are consistent with observed data. The appearance of life after the formation of the Earth is consistent with the data set under examination.
Holt, Geoff
2011-01-01
Project Earth Science: Astronomy, Revised 2nd Edition, involves students in activities that focus on Earth's position in our solar system. How do we measure astronomical distances? How can we look back in time as we gaze across vast distances in space? How would our planet be different without its particular atmosphere and distance to our star? What are the geometries among Earth, the Moon, and the Sun that yield lunar phases and seasons? Students explore these concepts and others in 11 teacher-tested activities.
Petrovsky, Eduard; Harinarayana, T; Herrero-Bervera, Emilio
2011-01-01
This volume combines review and solicited contributions, related to scientific studies of Division I of IAGA presented recently at its Scientific Assembly in Sopron in 2009. The book is aimed at intermediate to advanced readers dealing with the Earth's magnetic field generation, its historical records in rocks and geological formations - including links to geodynamics and magnetic dating, with magnetic carriers in earth materials, electromagnetic induction and conductivity studies of the Earth interior with environmental applications of rock magnetism and electromagnetism. The aim of the book
Lee, Hyung Joo; Aparecida de Mattias Sartori, Ivete; Alcântara, Paola Rebelatto; Vieira, Rogéria Acedo; Suzuki, Dalton; Gasparini Kiatake Fontão, Flávia; Tiossi, Rodrigo
2012-12-01
Primary and secondary stabilities of immediately loaded mandibular implants restored with fixed prostheses (FP) using rigid or semi-rigid splinting systems were clinically and radiographically evaluated. Fifteen edentulous patients were rehabilitated using hybrid FP; each had 5 implants placed between the mental foramens. Two groups were randomly divided: group 1-FP with the conventional rigid bar splinting the implants and group 2-semi-rigid cantilever extension system with titanium bars placed in the 2 distal abutment cylinders. Primary stability was evaluated using resonance frequency analysis after installation of the implant abutments. The measurements were made at 3 times: T0, at baseline; T1, 4 months after implant placement; and T2, 8 months after implant placement. Presence of mobility and inflammation in the implant surrounding regions were checked. Stability data were submitted to statistical analysis for comparison between groups (P < 0.05). Implant survival rate for the implants was of 100% in both groups. No significant differences in the mean implant stability quotient values were found for both groups from baseline and after the 8-month follow-up. The immediate loading of the implants was satisfactory, and both splinting conditions (rigid and semi-rigid) can be successfully used for the restoration of edentulous mandibles.
Golding, Suzanne D
2010-01-01
This volume integrates the latest findings on earliest life forms, identified and characterized in some of the oldest rocks on Earth. It places emphasis on the integration of analytical methods with observational techniques and experimental simulations.
Earth retaining structures manual
2009-10-29
The objectives of this policy are to obtain statewide uniformity, establish standard : procedures and delineate responsibility for the preparation and review of plans, : design and construction control of earth retaining structures. In addition, it i...
Muir, H
2000-01-01
The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).
Hide, Raymond; Dickey, Jean O.
1991-01-01
Recent improvements in geodetic data and practical meteorology have advanced research on fluctuations in the earth's rotation. The interpretation of these fluctuations is inextricably linked with studies of the dynamics of the earth-moon system and dynamical processes in the liquid metallic core of the earth (where the geomagnetic field originates), other parts of the earth's interior, and the hydrosphere and atmosphere. Fluctuations in the length of the day occurring on decadal time scales have implications for the topographay of the core-mantle boundary and the electrical, magnetic, ande other properties of the core and lower mantle. Investigations of more rapid fluctuations bear on meteorological studies of interannual, seasonal, and intraseasonal variations in the general circulation of the atmosphere and the response of the oceans to such variations.
National Research Council Canada - National Science Library
2008-01-01
The section features Earth Island's Dolphin Safe tuna . label (asking readers to look for tuna cans without the Dolphin Safe label and alert us so we can have the cans removed from store shelves...
Brumberg, V. A.; Ivanova, T. V.
2008-09-01
The aim of the present paper is to find the trigonometric solution of the equations of the Earth's rotation around its centre of mass in the form of polynomial trigonometric series (Poisson series) without secular and mixed therms. For that the techniques of the General Planetary Theory (GPT) ( Brumberg, 1995) and the Poisson Series Processor (PSP) (Ivanova, 1995) are used. The GPT allows to reduce the equations of the translatory motion of the major planets and the Moon and the equations of the Earth's rotation in Euler parameters to the secular system describing the evolution of the planetary and lunar orbits (independent of the Earth's rotation) and the evolution of the Earth's rotation (depending on the planetary and lunar evolution).
Whole-Earth Decompression Dynamics
Herndon, J. Marvin
2005-01-01
The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The i...
Large scale Brownian dynamics of confined suspensions of rigid particles.
Sprinkle, Brennan; Balboa Usabiaga, Florencio; Patankar, Neelesh A; Donev, Aleksandar
2017-12-28
We introduce methods for large-scale Brownian Dynamics (BD) simulation of many rigid particles of arbitrary shape suspended in a fluctuating fluid. Our method adds Brownian motion to the rigid multiblob method [F. Balboa Usabiaga et al., Commun. Appl. Math. Comput. Sci. 11(2), 217-296 (2016)] at a cost comparable to the cost of deterministic simulations. We demonstrate that we can efficiently generate deterministic and random displacements for many particles using preconditioned Krylov iterative methods, if kernel methods to efficiently compute the action of the Rotne-Prager-Yamakawa (RPY) mobility matrix and its "square" root are available for the given boundary conditions. These kernel operations can be computed with near linear scaling for periodic domains using the positively split Ewald method. Here we study particles partially confined by gravity above a no-slip bottom wall using a graphical processing unit implementation of the mobility matrix-vector product, combined with a preconditioned Lanczos iteration for generating Brownian displacements. We address a major challenge in large-scale BD simulations, capturing the stochastic drift term that arises because of the configuration-dependent mobility. Unlike the widely used Fixman midpoint scheme, our methods utilize random finite differences and do not require the solution of resistance problems or the computation of the action of the inverse square root of the RPY mobility matrix. We construct two temporal schemes which are viable for large-scale simulations, an Euler-Maruyama traction scheme and a trapezoidal slip scheme, which minimize the number of mobility problems to be solved per time step while capturing the required stochastic drift terms. We validate and compare these schemes numerically by modeling suspensions of boomerang-shaped particles sedimented near a bottom wall. Using the trapezoidal scheme, we investigate the steady-state active motion in dense suspensions of confined microrollers, whose
Large scale Brownian dynamics of confined suspensions of rigid particles
Sprinkle, Brennan; Balboa Usabiaga, Florencio; Patankar, Neelesh A.; Donev, Aleksandar
2017-12-01
We introduce methods for large-scale Brownian Dynamics (BD) simulation of many rigid particles of arbitrary shape suspended in a fluctuating fluid. Our method adds Brownian motion to the rigid multiblob method [F. Balboa Usabiaga et al., Commun. Appl. Math. Comput. Sci. 11(2), 217-296 (2016)] at a cost comparable to the cost of deterministic simulations. We demonstrate that we can efficiently generate deterministic and random displacements for many particles using preconditioned Krylov iterative methods, if kernel methods to efficiently compute the action of the Rotne-Prager-Yamakawa (RPY) mobility matrix and its "square" root are available for the given boundary conditions. These kernel operations can be computed with near linear scaling for periodic domains using the positively split Ewald method. Here we study particles partially confined by gravity above a no-slip bottom wall using a graphical processing unit implementation of the mobility matrix-vector product, combined with a preconditioned Lanczos iteration for generating Brownian displacements. We address a major challenge in large-scale BD simulations, capturing the stochastic drift term that arises because of the configuration-dependent mobility. Unlike the widely used Fixman midpoint scheme, our methods utilize random finite differences and do not require the solution of resistance problems or the computation of the action of the inverse square root of the RPY mobility matrix. We construct two temporal schemes which are viable for large-scale simulations, an Euler-Maruyama traction scheme and a trapezoidal slip scheme, which minimize the number of mobility problems to be solved per time step while capturing the required stochastic drift terms. We validate and compare these schemes numerically by modeling suspensions of boomerang-shaped particles sedimented near a bottom wall. Using the trapezoidal scheme, we investigate the steady-state active motion in dense suspensions of confined microrollers, whose
Space geodetic constraints on plate rigidity and global plate motions
Sella, Giovanni Federico
The Global Positioning System (GPS) has emerged over the last 10 years as the premier space geodetic technique for geologic observation with the benefits of both accuracy and economy. GPS data from more than 260 stations were processed utilizing GIPSY-OASIS software, and all available RINEX files for these stations beginning on January 1, 1993. The uniform processing strategy, combined with a rigorous independent error estimate of site velocities and the broad geographical distribution of these sites resulted in a global high-precision surface velocity data set. This data set has been used to: (1) compare the effects of different GPS antenna and monument types on data noise; (2) examine in detail the rigidity of the North America plate; (3) constrain the rate of deformation in the northern Gulf of Mexico; (4) define a model for Recent (Holocene) time global plate motions. The weighted root mean square scatter about the best fit line through the daily position estimates are used to assess the effects of different antenna and monument types on North America. The data set is sensitive to glacial isostatic adjustment as indicated by the decrease in chinu 2 from 1.3 to 1.0 by excluding those sites on rigid North America within a radius of 1,800 km of Hudson Bay. The resulting 64 site solution for the angular velocity of North America give a mean rate residual of 1 mm/yr. GULFNET, a regional GPS network created in 1997 in the northern Gulf Coast to measure strain across this active "passive margin" is described. Preliminary results suggest that deformation is occurring as predicted by the regional paradigm for deformation, i.e. Gulfward motion along normal faults. A new model for Recent global plate velocities (REVEL) describes the relative velocities of 14 plates. For several plate pairs, statistically significant differences are observed between the geodetically and geologically determined velocities reflecting changes in plate velocity through time. Some of the rate
[Aphakia correction with rigid contact lenses in congenital cataract].
Loudot, C; Jourdan, F; Benso, C; Denis, D
2012-10-01
To describe follow-up and evaluate functional results of rigid gas-permeable contact lens wear for the correction of aphakia in infants after surgery for congenital cataract. This retrospective study was performed on 23 eyes of 17 children (12 boys and five girls), between three days and 36 months of age (median 3.5 months), undergoing cataract extraction without primary intraocular lens implantation and fitted only with Menicon(®) Z material contact lenses. Initial fitting visits included history and family education. Subsequent examinations were performed at eight days, 15 days, 1 month, 6 months and 1 year. The four main parameters studied were fit characteristics, ease of manipulation, ocular integrity and lens integrity. Concurrently, functional results (visual acuity, oculomotor balance) and various prognostic factors (associated pathology, age at time of surgery, cataract density, unilaterality versus bilaterality, postoperative complications) were evaluated. Rigorous systematic amblyopia rehabilitation was performed. At the one-month exam, 60% of parents demonstrated proficiency with manipulating the lens. On one-year follow-up, three cases of failure were attributable to difficulties with lens manipulation. At one year, one infectious complication was detected. The lens material demonstrated good resistance to breakage (9% at one month) and only a mild tendency toward deposits (few or no deposits in 95% of cases at 1 month). With regard to visual outcome, among the children old enough to cooperate, visual acuity was better than 3/10 for nine out of 12 eyes, of which five eyes were 10/10. With regard to alignment, we noted 12 cases (70.6%) of strabismus postoperatively (ten esotropia, two exotropia). The factors predictive of good visual acuity correlated with those described in the literature: partial cataract, bilateral cataract, and absence of postoperative oculomotor disturbance. The characteristics of rigid gas-permeable contact lenses provide safety
Port-Based Modeling and Simulation of Mechanical Systems With Rigid and Flexible Links
Macchelli, A.; Melchiorri, C.; Stramigioli, Stefano
2009-01-01
In this paper, a systematic procedure for the defi- nition of the dynamical model in port-Hamiltonian form of me- chanical systems is presented as the result of the power-conserving interconnection of a set of basic components (rigid bodies, flexible links, and kinematic pairs). Since rigid bodies
Risk of perforation using rigid oesophagoscopy in the distal part of oesophagus
DEFF Research Database (Denmark)
Wennervaldt, Kasper; Melchiors, Jacob
2012-01-01
Endoscopic examination and treatment of disorders in the oesophagus have been a part of the otolaryngological specialty since the introduction of the rigid endoscope. Today, both flexible and rigid oesophagoscopy (RO) is used to that end. The aim of this study was to evaluate the safety of the RO....
30 CFR 7.28 - Test for flame resistance of rigid ventilation tubing.
2010-07-01
... material that falls on the floor of the test gallery during the igniting period. However, the suspended... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Test for flame resistance of rigid ventilation... and Ventilation Tubing § 7.28 Test for flame resistance of rigid ventilation tubing. (a) Test...
Mental set and creative thought in social conflict : Threat rigidity versus motivated focus
De Dreu, Carsten K. W.; Nijstad, Bernard A.
According to the traditional threat-rigidity reasoning, people in social conflict will be less flexible, less creative, more narrow-minded, and more rigid in their thinking when they adopt a conflict rather than a cooperation mental set. The authors propose and test an alternative, motivated focus
Rigid covariance as a natural extension of Painlev\\'e--Gullstrand space-times: gravitational waves
Jaén, Xavier
2016-01-01
The group of rigid motions is considered to guide the search for a natural system of space-time coordinates in General Relativity. This search leads us to a natural extension of the space-times that support Painlev\\'{e}--Gullstrand synchronization. As an interesting example, here we describe a system of rigid coordinates for the cross mode of gravitational linear plane waves.
21 CFR 886.5918 - Rigid gas permeable contact lens care products.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens care products. 886.5918 Section 886.5918 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5918 Rigid gas permeable contact lens care products. (a)...
The general motion of three mutually-interacting, axisymmetric spherical rigid bodies
El-Shaboury, S. M.; Dessoky, A. E. A.
1991-05-01
In this paper, the translational-rotational motions of an axisymmetric rigid body and two spherical rigid bodies under the influence of their mutual gravitational attraction are considered. The equations of motion in the canonical elements of Delaunay-Andoyer are obtained. The elements of motion in the zero and first approximations can be determined.
Effect of various factors on the rigidity of furniture cases | Tankut ...
African Journals Online (AJOL)
In general, the stiffer the end connection, the less the deflection of the case was observed. The results also indicated that rigidity of case furniture comes mainly from the gluing of the joining surfaces. Therefore, knowing the rigidity of the case furniture made of wood composites is fundamental to the design of safe, cost ...
Understanding Behavioural Rigidity in Autism Spectrum Conditions: The Role of Intentional Control
Poljac, Edita; Hoofs, Vincent; Princen, Myrthe M.; Poljac, Ervin
2017-01-01
Although behavioural rigidity belongs to the core symptoms of autism spectrum conditions, little is known about its underlying cognitive mechanisms. The current study investigated the role of intentional control mechanisms in behavioural rigidity in autism. Autistic individuals and their matched controls were instructed to repeatedly choose…
A new cantilever beam-rigid-body MEMS gyroscope: mathematical model and linear dynamics
Lajimi, Seyed Amir Mousavi; Abdel-Rahman, Eihab
2014-01-01
A new microbeam-rigid-body gyroscope is introduced and its static and dynamic behaviours are studied. The main structure includes a microbeam and an eccentric end-rigid-body influencing the dynamic and static characteristics of the sensor. The sensitivity of the device and the effect of system parameters on the microsystem's response are investigated.
21 CFR 177.1010 - Acrylic and modified acrylic plastics, semirigid and rigid.
2010-04-01
... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylic and modified acrylic plastics, semirigid... Acrylic and modified acrylic plastics, semirigid and rigid. Semirigid and rigid acrylic and modified acrylic plastics may be safely used as articles intended for use in contact with food, in accordance with...
21 CFR 178.3790 - Polymer modifiers in semirigid and rigid vinyl chloride plastics.
2010-04-01
... chloride plastics. 178.3790 Section 178.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... modifiers in semirigid and rigid vinyl chloride plastics. The polymers identified in paragraph (a) of this... semirigid and rigid vinyl chloride plastic food-contact articles prepared from vinyl chloride homopolymers...
The shape of a drop between two rigid fibers
Protiere, Suzie; Duprat, Camille; Stone, Howard A.
2012-11-01
Wetting of fibrous media is observed in many engineered systems, e.g. filters, textiles, paper etc. and may also be found in Nature (e.g. hair or feathers). To understand the basic response of such material when interacting with a liquid we study the model system of a finite volume of liquid on two parallel rigid fibers. A liquid wetting the fibers can adopt two distinct equilibrium shapes: a compact hemispherical drop shape or a long liquid column of constant cross-section. These two morphologies depend on the inter-fiber distance, the liquid volume, the fiber radius and the liquid-fiber contact angle. We study the transitions between a drop shape and a column by incrementally varying the inter-fiber distance and find that the transition depends on the global geometry of the system as well as on the volume of liquid. More surprisingly we find that these two morphological states may coexist for certain parameter values. These switches in morphologies may be used to manipulate or transport liquid at a small scale.
Bevel toric multicurve rigid gas-permeable lens for keratoconus.
Yanai, Ryoji; Ueda, Kiichi; Sonoda, Koh-Hei
2013-03-01
To evaluate the efficacy and safety of Twinbel bevel toric, a newly designed rigid gas-permeable (RGP) lens with a toric bevel curvature, for keratoconus. A retrospective analysis of nine eyes of patients with keratoconus who had been wearing RGP contact lenses and were switched to Twinbel bevel toric at Yamaguchi University Hospital. Visual acuity and contrast sensitivity were measured under photopic conditions. Complaint symptoms were recorded as primary outcome measures at follow-up visits. Efficacy and safety were evaluated at 12 weeks after the switch to Twinbel bevel toric or later. Five eyes (55.6 %) showed an improvement in visual acuity with Twinbel bevel toric compared with the previous lens, whereas four eyes (44.4 %) maintained the same visual acuity as before. The mean best corrected visual acuity ± SD with Twinbel bevel toric was 0.01 ± 0.40 logMAR, significantly better (P = 0.044, paired Student's t test) than that (0.23 ± 0.51 logMAR) with the previous lens. Contrast sensitivity and subjective complaint scores did not differ significantly between Twinbel bevel toric and the previous lens. No serious complications of Twinbel bevel toric wear were observed. Fitting of Twinbel bevel toric improved visual acuity in eyes affected by keratoconus, thus providing a viable alternative for management of such eyes.
Non-rigid registration of cervical spine MRI volumes.
Aktar, Mst Nargis; Alam, Md Jahangir; Pickering, Mark; Webb, Alexandra; Perriman, Diana
2015-01-01
Whiplash is the colloquial term for neck injuries caused by sudden extension of the cervical spine. Patients with chronic whiplash associated disorder (WAD) can experience neck pain for many years after the original injury. Researchers have found some evidence to suggest that chronic whiplash is related to the amount of intra-muscular fat in the cervical spine muscles. Hence, an important step towards developing a treatment for chronic WAD is a technique to accurately and efficiently measure the amount of intra-muscular fat in the muscles of the cervical spine. Our proposed technique for making this measurement is to automatically segment the cervical spine muscles using a fused volume created from multi-modal MRI volumes of the cervical spine. Multiple modes are required to enhance the boundaries between the different muscles to assist the following automatic segmentation process. However, before these multiple modes can be fused it is first necessary to accurately register these volumes. Hence, in this paper, we have proposed a new non-rigid multi-modal registration algorithm using the sum of conditional variance (SCV) with partial volume interpolation (PVI) similarity measure and Gauss-Newton (GN) optimization for the accurate registration of multi-modal cervical spine MRI volumes. The performance of the proposed approach is compared with the existing SCV based registration algorithm and the sum of the conditional squared deviation from the mode (SCSDM) method. The experimental results demonstrate that the proposed approach provides superior performance than the best existing approaches.
Rigid sphere room impulse response simulation: algorithm and applications.
Jarrett, D P; Habets, E A P; Thomas, M R P; Naylor, P A
2012-09-01
Simulated room impulse responses have been proven to be both useful and indispensable for comprehensive testing of acoustic signal processing algorithms while controlling parameters such as the reverberation time, room dimensions, and source-array distance. In this work, a method is proposed for simulating the room impulse responses between a sound source and the microphones positioned on a spherical array. The method takes into account specular reflections of the source by employing the well-known image method, and scattering from the rigid sphere by employing spherical harmonic decomposition. Pseudocode for the proposed method is provided, taking into account various optimizations to reduce the computational complexity. The magnitude and phase errors that result from the finite order spherical harmonic decomposition are analyzed and general guidelines for the order selection are provided. Three examples are presented: an analysis of a diffuse reverberant sound field, a study of binaural cues in the presence of reverberation, and an illustration of the algorithm's use as a mouth simulator.
Non-rigid registration for qualitiy control of printed materials
Badshah, Amir; O'Leary, Paul; Harker, Matthew; Sallinger, Christian
2011-07-01
This paper presents a new approach to non-rigid elastic registration. The method is applied to hyper spectral imaging data for the automatic quality control of decorative foils which are subject to deformation during lamination. A new image decimation procedure based on Savitzky-Golay smoothing is presented and applied in a multiresolution pyramid. Modified Fourier basis functions implemented by projection onto the orthogonal complement of a truncated Gram polynomial basis are presented. The modified functions are used to compute spectra whereby the Gibbs error associated with local gradients in the image are reduced. The paper also presents the first direct linear solution to weighted tensor product polynomial approximation. This method is used to regularize the patch coordinates, the solution is equivalent to a Galerkin type solution to a partial differential equations. The new solution is applied to published standard data set and to data acquired in a production environment. The speed of the new solution justifies explicit reference: the present solution implemented in MATLAB requires approximatly 1.3s to register an image of size 800 ×× 500 pixels. This is approximately a factor 10 to 100 faster than previously published results for the same data set.
A Condition Number for Non-Rigid Shape Matching
Ovsjanikov, Maks
2011-08-01
© 2011 The Author(s). Despite the large amount of work devoted in recent years to the problem of non-rigid shape matching, practical methods that can successfully be used for arbitrary pairs of shapes remain elusive. In this paper, we study the hardness of the problem of shape matching, and introduce the notion of the shape condition number, which captures the intuition that some shapes are inherently more difficult to match against than others. In particular, we make a connection between the symmetry of a given shape and the stability of any method used to match it while optimizing a given distortion measure. We analyze two commonly used classes of methods in deformable shape matching, and show that the stability of both types of techniques can be captured by the appropriate notion of a condition number. We also provide a practical way to estimate the shape condition number and show how it can be used to guide the selection of landmark correspondences between shapes. Thus we shed some light on the reasons why general shape matching remains difficult and provide a way to detect and mitigate such difficulties in practice.
Rigid fibrescope Bonfils: use in simulated difficult airway by novices
Directory of Open Access Journals (Sweden)
Piepho Tim
2009-07-01
Full Text Available Abstract Background The Bonfils intubation fibrescope is a promising alternative device for securing the airway. We examined the success rate of intubation and the ease of use in standardized simulated difficult airway scenarios by physicians. We compared the Bonfils to a classical laryngoscope with Macintosh blade. Methods 30 physicians untrained in the use of rigid fibrescopes but experienced in airway management performed endotracheal intubation in an airway manikin (SimMan, Laerdal, Kent, UK with three different airway conditions. We evaluated the success rate using the Bonfils (Karl Storz, Tuttlingen, Germany or the Macintosh laryngoscope, the time needed for securing the airway, and subjective rating of both techniques. Results In normal airway all intubations were successful using laryngoscope (100% vs. 82% using the Bonfils (p Conclusion The Bonfils can be successfully used by physicians unfamiliar with this technique in an airway manikin. The airway could be secured with at least the same success rate as using a Macintosh laryngoscope in difficult airway scenarios. Use of the Bonfils did not delay intubation in the presence of a difficult airway. These results indicate that intensive special training is advised to use the Bonfils effectively in airway management.
Impact of a Liquid Cone on a Plain Rigid Wall
Directory of Open Access Journals (Sweden)
A.A. Aganin
2016-03-01
Full Text Available A numerical study of high-speed (with the velocity of 250 m/s impact of a liquid cone (cone-like jet on a plain rigid wall has been performed. The range of the angles of inclination of the cone surface to the wall corresponds to that of their variation in the process of impact on the wall of a cylindrical jet with the semi-spherical end. The direct numerical simulation has been used on the basis of the gas dynamics equations by the CIP-CUP method on the dynamically adaptive Soroban-grids without explicit tracking of the interphase boundary. It has been found that three regimes of impact are set in the examined range of the angles. At the small angles the impact with shock wave attached to the wall without liquid spreading is realized. An abrupt transition to the regime with the shock wave detached from the wall together with the radial jet of the liquid spreading on the wall takes place with increasing the angle. A smooth transition to the shockless regime with the radial liquid jet is realized with further increasing the angle.
Optical characterization and polarization calibration for rigid endoscopes
Garcia, Missael; Gruev, Viktor
2017-02-01
Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.
Glass fiber and silica reinforced rigid polyurethane foams
Directory of Open Access Journals (Sweden)
M. W. Kim
2017-05-01
Full Text Available Ternary composites of rigid polyurethane foam (RPUF/glass fiber/silica as well as RPUF/glass fiber have been fabricated from glass fiber, silica, polymeric 4,4′-di-phenylmethane diisocyanate (PMDI and polyol using HFC 365mfc as blowing agent. Foam formation kinetics, morphology, thermal conductivity, glass transition temperature, decomposition temperatures as well as the mechanical strengths of the foam have been studied. With the addition an increasing amount of glass fiber cream time, rise time, gel time, tack free time, density, compression strength, thermal conductivity (k monotonically increased while the glass transition temperature showed a maximum at 2%. At constant glass fiber content (2%, addition of silica further increased the process times, density and compression strength while the Tg and thermal decomposition temperature showed a maximum at 3% silica. The k value of RFUF/glass fiber composite decreased with the addition of silica up to 3%, where it was even lower than the virgin RPUF. However, beyond the content k value increased. Overall, the variation of k value with silica content showed identical tendency with cells size and closed cells content.
Collapsed fat navigators for brain 3D rigid body motion.
Engström, Mathias; Mårtensson, Magnus; Avventi, Enrico; Norbeck, Ola; Skare, Stefan
2015-10-01
To acquire high-resolution 3D multi-slab echo planar imaging data without motion artifacts, using collapsed fat navigators. A fat navigator module (collapsed FatNav) was added to a diffusion-weighted 3D multi-slab echo planar imaging (DW 3D-MS EPI) sequence, comprising three orthogonal echo planar imaging readouts to track rigid body head motion in the image domain and performing prospective motion correction. The stability, resolution and accuracy of the navigator were investigated on phantoms and healthy volunteers. The experiments on phantoms and volunteers show that the navigator, depicting projections of the subcutaneous fat in of the head, is capable of correcting for head motion with insignificant bias compared to motion estimates derived from the water-signaling DWI images. Despite that this projection technique implies a non-sparse image appearance, collapsed FatNav data could be highly accelerated with parallel imaging, allowing three orthogonal 2D EPI readouts in about 6ms. By utilizing signal from the leading fat saturation RF pulse of the diffusion sequence, only the readout portion of the navigator needs to be added, resulting in a scan time penalty of only about 5%. Motion can be detected and corrected for with a 5-10Hz update frequency when combined with a sequence like the DW 3D-MS EPI. Copyright © 2015 Elsevier Inc. All rights reserved.
Canonical formalism for modelling and control of rigid body dynamics.
Gurfil, P
2005-12-01
This paper develops a new paradigm for stabilization of rigid-body dynamics. The state-space model is formulated using canonical elements, known as the Serret-Andoyer (SA) variables, thus far scarcely used for engineering applications. The main feature of the SA formalism is the reduction of the dynamics via the underlying symmetry stemming from conservation of angular momentum and rotational kinetic energy. The controllability of the system model is examined using the notion of accessibility, and is shown to be accessible from all points. Based on the accessibility proof, two nonlinear asymptotic feedback stabilizers are developed: a damping feedback is designed based on the Jurdjevic-Quinn method, and a Hamiltonian controller is derived by using the Hamiltonian as a natural Lyapunov function for the closed-loop dynamics. It is shown that the Hamiltonian control is both passive and inverse optimal with respect to a meaningful performance index. The performance of the new controllers is examined and compared using simulations of realistic scenarios from the satellite attitude dynamics field.
Unifying Rigid and Soft Bodies Representation: The Sulfur Physics Engine
Directory of Open Access Journals (Sweden)
Dario Maggiorini
2014-01-01
Full Text Available Video games are (also real-time interactive graphic simulations: hence, providing a convincing physics simulation for each specific game environment is of paramount importance in the process of achieving a satisfying player experience. While the existing game engines appropriately address many aspects of physics simulation, some others are still in need of improvements. In particular, several specific physics properties of bodies not usually involved in the main game mechanics (e.g., properties useful to represent systems composed by soft bodies, are often poorly rendered by general-purpose engines. This issue may limit game designers when imagining innovative and compelling video games and game mechanics. For this reason, we dug into the problem of appropriately representing soft bodies. Subsequently, we have extended the approach developed for soft bodies to rigid ones, proposing and developing a unified approach in a game engine: Sulfur. To test the engine, we have also designed and developed “Escape from Quaoar,” a prototypal video game whose main game mechanic exploits an elastic rope, and a level editor for the game.
Obstacles to developing sustainable cities: the real estate rigidity trap
Directory of Open Access Journals (Sweden)
V. Kelly Turner
2017-06-01
Full Text Available Sprawl patterns of urbanization have large environmental consequences, and sustainable alternatives to conventional urban patterns of development have been promoted by a subset of planners, design professionals, and municipalities. These alternatives have not been widely adopted among real estate developers, actors with large influence over urban form and function. Existing explanations for this failure enumerate market and regulatory barriers but do not sufficiently describe the institutional structures that allow conventional approaches to prevail. A failure of real estate developers to adopt alternative forms of development can best be described in terms of a rigidity trap. Specifically, norms of practice within the real estate development industry combine with market and regulatory factors to favor existing practices and limit innovation. Moreover, these institutional factors also buffer the real estate development industry from feedback mechanisms and external signals that might otherwise trigger adaptation. Addressing the environmental consequences of urbanization not only requires novel approaches to urban design, but will also necessitate addressing systemic pathologies in the design implementation process.
Microscopic theory of topologically entangled fluids of rigid macromolecules
Sussman, Daniel M.; Schweizer, Kenneth S.
2011-06-01
We present a first-principles theory for the slow dynamics of a fluid of entangling rigid crosses of zero excluded volume based on a generalization of the dynamic mean-field approach of Szamel for infinitely thin nonrotating rods. The latter theory exactly includes topological constraints at the two-body collision level and self-consistently renormalizes an effective diffusion tensor to account for many-body effects. Remarkably, it predicts scaling laws consistent with the phenomenological reptation-tube predictions of Doi and Edwards for the long-time diffusion and the localization length in the heavily entangled limit. We generalize this approach to a different macromolecular architecture, infinitely thin three-dimensional crosses, and also extend the range of densities over which a dynamic localization length can be calculated for rods. Ideal gases of nonrotating crosses have recently received attention in computer simulations and are relevant as a simple model of both a strong-glass former and entangling star-branched polymers. Comparisons of our theory with these simulations reveal reasonable agreement for the magnitude and reduced density dependence of the localization length and also the self-diffusion constant if the consequences of local density fluctuations are taken into account.
Active elastic dimers: Cells moving on rigid tracks
Lopez, J. H.; Das, Moumita; Schwarz, J. M.
2014-09-01
Experiments suggest that the migration of some cells in the three-dimensional extracellular matrix bears strong resemblance to one-dimensional cell migration. Motivated by this observation, we construct and study a minimal one-dimensional model cell made of two beads and an active spring moving along a rigid track. The active spring models the stress fibers with their myosin-driven contractility and α-actinin-driven extendability, while the friction coefficients of the two beads describe the catch and slip-bond behaviors of the integrins in focal adhesions. In the absence of active noise, net motion arises from an interplay between active contractility (and passive extendability) of the stress fibers and an asymmetry between the front and back of the cell due to catch-bond behavior of integrins at the front of the cell and slip-bond behavior of integrins at the back. We obtain reasonable cell speeds with independently estimated parameters. We also study the effects of hysteresis in the active spring, due to catch-bond behavior and the dynamics of cross linking, and the addition of active noise on the motion of the cell. Our model highlights the role of α-actinin in three-dimensional cell motility and does not require Arp2/3 actin filament nucleation for net motion.
Finite Element Investigation of the Deterioration of Doweled Rigid Pavements
Ghauch, Ziad G
2011-01-01
The purpose of this study is to describe the failure of concrete around dowel bars in jointed rigid pavements, and the resulting effect on the pavement performance. In fact, under repetitive vehicle loading, concrete in contact with the dowel bar deteriorates, particularly at the joint face. The degradation of concrete around the dowel negatively affects the latter's performance in terms of transferring wheel loads through vertical shear action. In this context, a nonlinear 3D Finite Element analysis was performed using the commercial FE code Abaqus (v-6.11). The FE model was validated with classical analytical solutions of shear and moment along the dowel. A concrete damaged plasticity model was used for the PCC slab to model the degradation of concrete matrix around the dowels under incremental loading. Results obtained show, among other things, that the degradation of concrete matrix around the dowel was found to initiate at the face of the joint and propagate towards the interior of the dowel. Also, resul...
Semi-Implicit Reversible Algorithms for Rigid Body Rotational Dynamics
Energy Technology Data Exchange (ETDEWEB)
Nukala, Phani K [ORNL; Shelton Jr, William Allison [ORNL
2006-09-01
This paper presents two semi-implicit algorithms based on splitting methodology for rigid body rotational dynamics. The first algorithm is a variation of partitioned Runge-Kutta (PRK) methodology that can be formulated as a splitting method. The second algorithm is akin to a multiple time stepping scheme and is based on modified Crouch-Grossman (MCG) methodology, which can also be expressed as a splitting algorithm. These algorithms are second-order accurate and time-reversible; however, they are not Poisson integrators, i.e., non-symplectic. These algorithms conserve some of the first integrals of motion, but some others are not conserved; however, the fluctuations in these invariants are bounded over exponentially long time intervals. These algorithms exhibit excellent long-term behavior because of their reversibility property and their (approximate) Poisson structure preserving property. The numerical results indicate that the proposed algorithms exhibit superior performance compared to some of the currently well known algorithms such as the Simo-Wong algorithm, Newmark algorithm, discrete Moser-Veselov algorithm, Lewis-Simo algorithm, and the LIEMID[EA] algorithm.
Use of Terrestrial Laser Scanner for Rigid Airport Pavement Management.
Barbarella, Maurizio; D'Amico, Fabrizio; De Blasiis, Maria Rosaria; Di Benedetto, Alessandro; Fiani, Margherita
2017-12-26
The evaluation of the structural efficiency of airport infrastructures is a complex task. Faulting is one of the most important indicators of rigid pavement performance. The aim of our study is to provide a new method for faulting detection and computation on jointed concrete pavements. Nowadays, the assessment of faulting is performed with the use of laborious and time-consuming measurements that strongly hinder aircraft traffic. We proposed a field procedure for Terrestrial Laser Scanner data acquisition and a computation flow chart in order to identify and quantify the fault size at each joint of apron slabs. The total point cloud has been used to compute the least square plane fitting those points. The best-fit plane for each slab has been computed too. The attitude of each slab plane with respect to both the adjacent ones and the apron reference plane has been determined by the normal vectors to the surfaces. Faulting has been evaluated as the difference in elevation between the slab planes along chosen sections. For a more accurate evaluation of the faulting value, we have then considered a few strips of data covering rectangular areas of different sizes across the joints. The accuracy of the estimated quantities has been computed too.
Use of Terrestrial Laser Scanner for Rigid Airport Pavement Management
Directory of Open Access Journals (Sweden)
Maurizio Barbarella
2017-12-01
Full Text Available The evaluation of the structural efficiency of airport infrastructures is a complex task. Faulting is one of the most important indicators of rigid pavement performance. The aim of our study is to provide a new method for faulting detection and computation on jointed concrete pavements. Nowadays, the assessment of faulting is performed with the use of laborious and time-consuming measurements that strongly hinder aircraft traffic. We proposed a field procedure for Terrestrial Laser Scanner data acquisition and a computation flow chart in order to identify and quantify the fault size at each joint of apron slabs. The total point cloud has been used to compute the least square plane fitting those points. The best-fit plane for each slab has been computed too. The attitude of each slab plane with respect to both the adjacent ones and the apron reference plane has been determined by the normal vectors to the surfaces. Faulting has been evaluated as the difference in elevation between the slab planes along chosen sections. For a more accurate evaluation of the faulting value, we have then considered a few strips of data covering rectangular areas of different sizes across the joints. The accuracy of the estimated quantities has been computed too.
Non-Invasive Ocular Rigidity Measurement: A Differential Tonometry Approach
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Efstathios T. Detorakis
2015-12-01
Full Text Available Purpose: Taking into account the fact that Goldmann applanation tonometry (GAT geometrically deforms the corneal apex and displaces volume from the anterior segment whereas Dynamic Contour Tonometry (DCT does not, we aimed at developing an algorithm for the calculation of ocular rigidity (OR based on the differences in pressure and volume between deformed and non-deformed status according to the general Friedenwald principle of differential tonometry. Methods: To avoid deviations of GAT IOP from true IOP in eyes with corneas different from the “calibration cornea” we applied the previously described Orssengo-Pye algorithm to calculate an error coefficient “C/B”. To test the feasibility of the proposed model, we calculated the OR coefficient (r in 17 cataract surgery candidates (9 males and 8 females. Results: The calculated r according to our model (mean ± SD, range was 0.0174 ± 0.010 (0.0123–0.022 mmHg/μL. A negative statistically significant correlation between axial length and r was detected whereas correlations between r and other biometric parameters examined were statistically not significant. Conclusions: The proposed method may prove a valid non-invasive tool for the measurement method of OR, which could help in introducing OR in the decision-making of the routine clinical practice.
Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates
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V. A. Zverev
2016-01-01
Full Text Available The aim is to determine weight suspension rigidity in aggregates designed to perform technological transport-erector operations at the miscellaneous launch complexes.We consider the weight suspension comprising the following distinctive structural components: the executive weight-lowering mechanism, polyspast mechanism, rope, traverse, and rods. A created structural dynamic model of suspension allowed us to define weight suspension rigidity. Within the framework of design analysis of a dynamic model we determined the rigidity of its structural units, i.e. traverse, rope, and polyspast.Known analytical relationships were used to calculate the rope rigidity. To determine rigidity of polyspast and traverse have been created special models based on the finite element method. For each model deformation in the specific points under the test load have been defined. Data obtained were used to determine trigidity of traverses and polyspast, and also rigidity of suspension in total. The rigidity models of polispast mechanism and traverse have been developed and calculated using the software complex "Zenit-95".As the research results, the paper presents a dynamic model of the weight suspension of the transport-erector aggregate, the finite element models of the polispast mechanism and traverse, an algorithm for determining the weight suspension rigidity and relevant analytical relationships.Independent calculation of weight suspension rigidity enables us to simplify further dynamic calculation of the aggregate-weight system because it allows attaining a simpler model of the aggregate-weight system that uses the weight suspension model as an element of equivalent rigidity. Despite this simplification the model allows us to determine correctly weight movement parameters and overloads in the aggregate-weight system in the process of technical operations.
Xu, Chunyan; Chang, Jingcai; Meng, Zhen; Wang, Xiang; Zhang, Jing; Cui, Lin; Ma, Chunyuan
2016-10-01
The fine particles are considered a significant pollution problem. The wet electrostatic precipitators (ESPs) have advantages of efficient collection of the fine particles with lower pressure drop and eliminating reentrainment. The wetting properties of the collector surfaces have significantly important effect on wet ESPs' stable and secure operation. The modified rigid collector (MRC) was modified by coating specific vinyl ester resin composites and loose glass fiber cloth over the conventional carbon steel in a certain way. The rigid collector surfaces before and after modification had been characterized by scanning electron microscopy (SEM) and interface tensiometer. The effect of operating temperatures on the wetting properties of the rigid collector surfaces before and after modification was investigated. The temperature range was 40~90 °C, and the wetting properties contained liquid holdup, surface flow rate, film rate, average film thickness, and critical saturation time. The modified rigid collector surface exhibited excellent wetting properties at the operating temperatures. The fine particles collection performance compared among the MRC, the conventional rigid collector (CRC), and the flexible collector (FC) in the wet ESPs was investigated. The effects of the applied voltage, the water film, corona power, and the specific collecting area on the fine particles collection were evaluated. The modified rigid collector provided high fine particles collection effect with lower energy and water consumption. To improve the submicron particles collection efficiency and decrease energy and water consumption, the formation of uniform water film over the collector surfaces has been widely studied. The modified rigid collector was modified by coating specific vinyl ester resin composites and loose glass fiber cloth (ERGF) over the conventional carbon steel (CCS) in a certain way. The modified rigid collector surface exhibited excellent wetting properties. The wet
Optimal Safety Earthing – Earth Electrode Sizing Using A ...
African Journals Online (AJOL)
In this paper a deterministic approach in the sizing of earth electrode using the permissible touch voltage criteria is presented. The deterministic approach is effectively applied in the sizing of the length of earth rod required for the safe earthing of residential and facility buildings. This approach ensures that the earthing ...
Energy Technology Data Exchange (ETDEWEB)
Ojima, D. [ed.
1992-12-31
The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.
Gopalswamy, Natchimuthuk
2012-01-01
Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.
1992-01-01
On December 16, 1992, 8 days after its encounter with Earth, the Galileo spacecraft looked back from a distance of about 6.2 million kilometers (3.9 million miles) to capture this remarkable view of the Moon in orbit about Earth. The composite photograph was constructed from images taken through visible (violet, red) and near-infrared (1.0-micron) filters. The Moon is in the foreground; its orbital path is from left to right. Brightly colored Earth contrasts strongly with the Moon, which reacts only about one-third as much sunlight as our world. To improve the visibility of both bodies, contrast and color have been computer enhanced. At the bottom of Earth's disk, Antarctica is visible through clouds. The Moon's far side can also be seen. The shadowy indentation in the Moon's dawn terminator--the boundary between its dark and lit sides--is the South Pole-Aitken Basin, one of the largest and oldest lunar impact features. This feature was studied extensively by Galileo during the first Earth flyby in December 1990.
The earth's hydrological cycle
Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M
2014-01-01
This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...
Google Earth and Map Projections
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Nedjeljko Frančula
2010-06-01
Full Text Available By starting Google Earth, the screen shows Earth from a great distance, e.g. from a satellite rotating around the Earth (Fig. 1. The graticule is drawn by using the Grid function from the View menu. Google Earth is a virtual globe which can be rotated in all directions using a mouse.
Passivity-Based Control of a Rigid Electrodynamic Tether
DEFF Research Database (Denmark)
Larsen, Martin Birkelund; Blanke, Mogens
2011-01-01
parts, a feedback connection, which stabilizes the open-loop equilibrium, and a bias term, which is able to drive the system trajectory away from this equilibrium, a feature necessary to obtain orbit adjustment capabilities of the electrodynamic tether. It is then shown how the periodic solutions......Electrodynamic tethers provide actuation for performing orbit correction of spacecrafts. When an electrodynamic tether system is orbiting the Earth in an inclined orbit, periodic changes in the magnetic field result in a family of unstable periodic solutions in the attitude motion. This paper shows...
Flexible Versus Rigid Methods Of Intravenous Thrombolysis In Iran
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Kavian Ghandehari
2017-02-01
exclusion critera as illustrated above. This method will increase the probability of symptomatic intracerebral hemorrhage and death and may increase numbers of legal condemnations for treating physician. Rigid method is prohibition of violations from standard protocols of thrombolysis which decreases both numbers of managed patients and thrombolysis contraindications. Physicians who prefer the first therapeutic strategy refer to data of published articles and guidelines of American and European stroke societies. There are two points of view; first, the Iranian neurologists do not have thrombolysis experience as well as western neurologusts. For instance very limited number of Iranian neurologists have enough experience for detection of ASPECT score. Second, due to some social factors number of legal condemnations due to medical malpractice has been hugely increased in recent two decades in Iran. Based on these points second strategy is more wise for Iranian neurologists. The speaker has made a standard protocol of thrombolysis based on international gudelines and his experience. This standard protocol which is designed according to the rigid method is available by search in Google engine and is provided in Persian language.
Rigid polyurethane/oil palm fibre biocomposite foam
Alis, Adilah; Majid, Rohah A.; Nasir, Izzah Athirah Ahmad; Mustaffa, Nor Syatika; Hassan, Wan Hasamuddin Wan
2017-07-01
Rigid polyurethane (PU) biocomposite foam had been successfully prepared by reacting palm oil-derived polyol (PO-p) with polymeric 4, 4-diphenylmethane diisocynate (p-MDI). Two types of alkali-treated oil palm fibres namely, empty fruit bunch (EFB) and palm pressed fibre (PPF) were used as fillers to be incorporated into PU foam at 2.5 wt%, 5 wt% and 7.5 wt% fibre loadings. The effects of these fibres on surface morphology, compressive strength and thermal transition behaviours of biocomposite foams were investigated. Fourier transform infra-red (FTIR) analysis confirmed the formation of urethane linkages (-NHCOO) in all samples at 1530-1540 cm-1. Differential scanning calorimetry (DSC) analysis showed the average melting peak temperature (Tm) of biocomposite foams (132°C) were lower Tm than that of pure PU foam (161.67°C) and the increase amount of fibres did not give significant effect on the Tm of both biocomposite systems. Meanwhile, the microscopic images of PU-PPF foams exhibited smaller and uniform cell size morphologies compared with the PU-EFB foams that had coarse and irregular cell sizes, especially at 7.5wt% EFB. These findings were manifested with the gradually increase of compressive strength of PU-PPF at all PPF ratios while for PU-EFB system, the compressive strength increased up to 5 wt% before reduced at 7.5 wt% loading. It was thought due to the residual oil in PPF fibre had plasticized the PU matrix to a little extent, thus helping the dispersion of PPF fibre across the matrix.
Diagnostic value of rigid body rotation in noncompaction cardiomyopathy.
van Dalen, Bas M; Caliskan, Kadir; Soliman, Osama I I; Kauer, Floris; van der Zwaan, Heleen B; Vletter, Wim B; van Vark, Laura C; Ten Cate, Folkert J; Geleijnse, Marcel L
2011-05-01
The diagnosis of noncompaction cardiomyopathy (NCCM) remains subject to controversy. Because NCCM is probably caused by an intrauterine arrest of the myocardial fiber compaction during embryogenesis, it may be anticipated that the myocardial fiber helices, normally causing left ventricular (LV) twist, will also not develop properly. The resultant LV rigid body rotation (RBR) may strengthen the diagnosis of NCCM. The purpose of the current study was to explore the diagnostic value of RBR in a large group of patients with prominent trabeculations. The study comprised 15 patients with dilated cardiomyopathy, 52 healthy subjects, and 52 patients with prominent trabeculations, of whom a clinical expert in NCCM defined 34 as having NCCM. LV rotation patterns were determined by speckle-tracking echocardiography and defined as follows: pattern 1A, completely normal rotation (initial counterclockwise basal and clockwise apical rotation, followed by end-systolic clockwise basal and counterclockwise apical rotation); pattern 1B, partly normal rotation (normal end-systolic rotation but absence of initial rotation in the other direction); and pattern 2, RBR (rotation at the basal and apical level predominantly in the same direction). The majority of normal subjects had LV rotation pattern 1A (98%), whereas the 18 subjects with hypertrabeculation not fulfilling diagnostic criteria for NCCM predominantly had pattern 1B (71%), and the 34 patients with NCCM predominantly had pattern 2 (88%). None of the patients with dilated cardiomyopathy showed RBR. Sensitivity and specificity of RBR for differentiating NCCM from "hypertrabeculation" were 88% and 78%, respectively. RBR is an objective, quantitative, and reproducible functional criterion with good predictive value for the diagnosis of NCCM as determined by expert opinion. Copyright © 2011 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.
Apical clearance rigid contact lenses induce corneal steepening.
Swarbrick, Helen A; Hiew, Ross; Kee, Ai Vy; Peterson, Sophia; Tahhan, Nina
2004-06-01
Anecdotal reports suggest that steeply fitted rigid contact lenses can induce corneal steepening and myopic shifts in refraction. This study investigated changes in corneal topography, corneal thickness, and refraction after short-term wear of apical clearance lenses. : Ten young adults participated in the study in which apical clearance lenses (Conoid, Hydron Pty. Ltd., Frenchs Forest, NSW, Australia), fitted approximately 0.3 mm steeper than the flattest keratometric reading, were worn for 4 h. A polymethyl methacrylate (PMMA) lens was worn in one eye, and a Boston XO lens (Bausch & Lomb, Rochester, NY) was worn in the other. Lenses were nonfenestrated in the first trial, and a single midperipheral fenestration was incorporated for a second trial. Corneal topography was monitored using the EyeSys topographic analysis system (EyeSys Vision, Inc., Houston, TX); central corneal thickness was quantified using ultrasonic pachometry; and refraction and anterior ocular response were also monitored. Significant central corneal edema (8.2 +/- 2.2%) was demonstrated in the PMMA lens-wearing eye only. Fenestration did not reduce the edema response. We found significant corneal steepening over a 5- to 6-mm central zone, which was more pronounced in the PMMA lens-wearing eye and was modified by lens fenestration. The curvature changes altered central corneal shape from prolate (Q = -0.06 +/- 0.10) to oblate (Q = -0.26 +/- 0.31). A slight myopic shift in refraction (-0.38 +/- 0.60 D) was found with the PMMA lenses only. : Apical clearance lenses induce corneal steepening after short-term wear. Although corneal molding is implicated as the primary factor driving the shape change, corneal edema and postlens tear film pressures can modify this response.
Success of Rigid Gas Permeable Contact Lens Fitting.
Ortiz-Toquero, Sara; Martin, Mario; Rodriguez, Guadalupe; de Juan, Victoria; Martin, Raul
2017-05-01
To assess the percentage of successful rigid gas permeable (GP) contact lenses (CLs) fit for both refractive and therapeutic reasons. New CLs (soft or GP) fittings were retrospectively analyzed and divided into refractive and therapeutic prescriptions. A standardized fitting protocol that included complete CLs information after a first eye examination, a diagnostic fitting visit, a dispensing visit, and a prescribing visit was used in all fittings. A GP fitting was defined as successful if full-time wear and optimal ocular surface physiology were both achieved at the review assessment 2 to 3 weeks after lens dispensing. Of 232 new CLs fittings analyzed, 166 were refractive fittings (71.6%) and 66 were therapeutic (28.4%). Of the refractive fittings, 88 subjects (53%) were initially fitted with GP CLs and 61 (69.3%) of these met the criteria for successful GP fitting. Within this group, a different percentage of successful fits were found for neophyte (72%), previous soft lens wearers (62%), and previous GP wearers (92.3%). Of the therapeutic fittings, 61 subjects (92.4%) were initially fitted with GP CLs and 59 (96.7%) of these met the criteria for successful GP fitting. Following a standardized CLs fitting protocol, a relatively high percentage of successful GP fits was achieved for refractive (7/10 subjects) and therapeutic (9/10 subjects) prescriptions. These results will improve the information available to patients and aid in their CL choices by providing them with a realistic attitude. It will also help eye care practitioners in their clinical activities by providing evidence-based information.
Survey of Non-Rigid Registration Tools in Medicine.
Keszei, András P; Berkels, Benjamin; Deserno, Thomas M
2017-02-01
We catalogue available software solutions for non-rigid image registration to support scientists in selecting suitable tools for specific medical registration purposes. Registration tools were identified using non-systematic search in Pubmed, Web of Science, IEEE Xplore® Digital Library, Google Scholar, and through references in identified sources (n = 22). Exclusions are due to unavailability or inappropriateness. The remaining (n = 18) tools were classified by (i) access and technology, (ii) interfaces and application, (iii) living community, (iv) supported file formats, and (v) types of registration methodologies emphasizing the similarity measures implemented. Out of the 18 tools, (i) 12 are open source, 8 are released under a permissive free license, which imposes the least restrictions on the use and further development of the tool, 8 provide graphical processing unit (GPU) support; (ii) 7 are built on software platforms, 5 were developed for brain image registration; (iii) 6 are under active development but only 3 have had their last update in 2015 or 2016; (iv) 16 support the Analyze format, while 7 file formats can be read with only one of the tools; and (v) 6 provide multiple registration methods and 6 provide landmark-based registration methods. Based on open source, licensing, GPU support, active community, several file formats, algorithms, and similarity measures, the tools Elastics and Plastimatch are chosen for the platform ITK and without platform requirements, respectively. Researchers in medical image analysis already have a large choice of registration tools freely available. However, the most recently published algorithms may not be included in the tools, yet.
Single homopolypeptide chains collapse into mechanically rigid conformations
Dougan, Lorna; Li, Jingyuan; Badilla, Carmen L.; Berne, B. J.; Fernandez, Julio M.
2009-01-01
Huntington's disease is linked to the insertion of glutamine (Q) in the protein huntingtin, resulting in polyglutamine (polyQ) expansions that self-associate to form aggregates. While polyQ aggregation has been the subject of intense study, a correspondingly thorough understanding of individual polyQ chains is lacking. Here we demonstrate a single molecule force-clamp technique that directly probes the mechanical properties of single polyQ chains. We have made polyQ constructs of varying lengths that span the length range of normal and diseased polyQ expansions. Each polyQ construct is flanked by the I27 titin module, providing a clear mechanical fingerprint of the molecule being pulled. Remarkably, under the application of force, no extension is observed for any of the polyQ constructs. This is in direct contrast with the random coil protein PEVK of titin, which readily extends under force. Our measurements suggest that polyQ chains form mechanically stable collapsed structures. We test this hypothesis by disrupting polyQ chains with insertions of proline residues and find that their mechanical extensibility is sensitive to the position of the proline interruption. These experiments demonstrate that polyQ chains collapse to form a heterogeneous ensemble of conformations that are mechanically resilient. We further use a heat-annealing molecular dynamics protocol to extensively search the conformation space and find that polyQ can exist in highly mechanically stable compact globular conformations. The mechanical rigidity of these collapsed structures may exceed the functional ability of eukaryotic proteasomes, resulting in the accumulation of undigested polyQ sequences in vivo. PMID:19549822
Rigid Polyurethane Foam Thermal Insulation Protected with Mineral Intumescent Mat
Directory of Open Access Journals (Sweden)
Kirpluks Mikelis
2014-12-01
Full Text Available One of the biggest disadvantages of rigid polyurethane (PU foams is its low thermal resistance, high flammability and high smoke production. Greatest advantage of this thermal insulation material is its low thermal conductivity (λ, which at 18-28 mW/(m•K is superior to other materials. To lower the flammability of PU foams, different flame retardants (FR are used. Usually, industrially viable are halogenated liquid FRs but recent trends in EU regulations show that they are not desirable any more. Main concern is toxicity of smoke and health hazard form volatiles in PU foam materials. Development of intumescent passive fire protection for foam materials would answer problems with flammability without using halogenated FRs. It is possible to add expandable graphite (EG into PU foam structure but this increases the thermal conductivity greatly. Thus, the main advantage of PU foam is lost. To decrease the flammability of PU foams, three different contents 3%; 9% and 15% of EG were added to PU foam formulation. Sample with 15% of EG increased λ of PU foam from 24.0 to 30.0 mW/(m•K. This paper describes the study where PU foam developed from renewable resources is protected with thermally expandable intumescent mat from Technical Fibre Products Ltd. (TFP as an alternative to EG added into PU material. TFP produces range of mineral fibre mats with EG that produce passive fire barrier. Two type mats were used to develop sandwich-type PU foams. Also, synergy effect of non-halogenated FR, dimethyl propyl phosphate and EG was studied. Flammability of developed materials was assessed using Cone Calorimeter equipment. Density, thermal conductivity, compression strength and modulus of elasticity were tested for developed PU foams. PU foam morphology was assessed from scanning electron microscopy images.
Ebisawa, K.; Koyama, Y.; Saito, A.; Sakamoto, S.; Ishii, M.; Kumano, Y.; Hazumi, Y.
2015-09-01
In this paper we introduce two independent projects in progress in Japan. Dagik Earth is a visualization project of the Earth and planets on a spherical screen using only a standard PC and a projector. Surface images of the Earth or planets (or whatever having spherical shape) in the equirectangular (plate carre) projection are projected on a spherical screen in the orthographic projection. As a result, the spherical screen becomes a virtual digital globe, which can be rotated using mouse or remote controller. Inter-university Upper atmosphere Global Observation NETwork (IUGONET) is a collaboration of five Japanese institutes to build a comprehensive database system for the metadata of the upper-atmospheric data taken by these institutes. We explain the IUGONET metadata database and iUgonet Data Analysis Software (UDAS) for upper atmospheric research.
Heller, René
2015-01-01
Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.
Patient preferences and comparative ocular responses to rigid and soft contact lenses.
Fonn, D; Gauthier, C A; Pritchard, N
1995-12-01
Patient preferences and ocular responses were compared between rigid and soft contact lenses by randomly fitting 32 neophyte subjects with a rigid lens in 1 eye and a soft lens in the contralateral eye. Twenty-seven of 32 subjects completed the 3-month study and 16 subjects were willing to continue for an additional 3-month extension. Subjects preferred the comfort and handling of the soft lens but preferred the vision provided by the rigid lens and initially its ease of maintenance. There was also a marked preference for the soft lens when all aspects of lens wear were compared. Objectively, the rigid lenses were responsible for more ocular changes than the soft lenses. Palpebral aperture sizes of the rigid gas permeable (RGP) wearing eyes decreased significantly (0.5 mm; p lens wearing eyes. The incidence of corneal staining was significantly greater in the rigid lens wearing eye (50% RGP vs. 22% soft) but limbal injection was greater in the soft lens wearing eye (18% soft vs. 6% RGP). Refractive sphere, cylinder, and corneal astigmatism decreased in the rigid lens wearing eye after 3 months. This daily wear clinical trial has shown a marked subjective preference for wearing soft lenses with fewer short-term ocular effects.
Thurber, Bonnie B.
2015-08-01
How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.
NoRMCorre: An online algorithm for piecewise rigid motion correction of calcium imaging data.
Pnevmatikakis, Eftychios A; Giovannucci, Andrea
2017-11-01
Motion correction is a challenging pre-processing problem that arises early in the analysis pipeline of calcium imaging data sequences. The motion artifacts in two-photon microscopy recordings can be non-rigid, arising from the finite time of raster scanning and non-uniform deformations of the brain medium. We introduce an algorithm for fast Non-Rigid Motion Correction (NoRMCorre) based on template matching. NoRMCorre operates by splitting the field of view (FOV) into overlapping spatial patches along all directions. The patches are registered at a sub-pixel resolution for rigid translation against a regularly updated template. The estimated alignments are subsequently up-sampled to create a smooth motion field for each frame that can efficiently approximate non-rigid artifacts in a piecewise-rigid manner. Existing approaches either do not scale well in terms of computational performance or are targeted to non-rigid artifacts arising just from the finite speed of raster scanning, and thus cannot correct for non-rigid motion observable in datasets from a large FOV. NoRMCorre can be run in an online mode resulting in comparable to or even faster than real time motion registration of streaming data. We evaluate its performance with simple yet intuitive metrics and compare against other non-rigid registration methods on simulated data and in vivo two-photon calcium imaging datasets. Open source Matlab and Python code is also made available. The proposed method and accompanying code can be useful for solving large scale image registration problems in calcium imaging, especially in the presence of non-rigid deformations. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.
Comparison of elastic versus rigid suture material for peripheral sutures in tendon repair.
Nozaki, Kenji; Mori, Ryuji; Ryoke, Koji; Uchio, Yuji
2012-06-01
For secure tendon repair, while core suture materials have been previously investigated, the optimum material for peripheral sutures remains unclear. Transected bovine gastrocnemius tendons were repaired by 2-strand side-locking loop technique using no.2 braided polyblend polyethylene thread for the core suture. Then, 8-strand peripheral cross-stitches were added using either 2-0 rigid sutures (braided polyblend polyethylene) or USP 2-0-sized elastic sutures (nylon). The holding area of each peripheral suture was set at either 3 × 1 mm (shallow holding) or 6 × 2 mm (deep holding). Therefore, 4 groups were compared (the shallow-rigid, deep-rigid, shallow-elastic, and deep-elastic groups). The gap formation, ultimate tensile strength, and suture migration state were measured after 500 cyclic loadings (from 10 to 200 N). The shallow-rigid group had inferior outcomes compared to the other groups. Although the deep-rigid group had the smallest gap and highest ultimate strength, all peripheral sutures had failure prior to core suture rupture. The two elastic groups showed no significant differences, irrespective of the size of the holding area. Suture migration did not occur in the two elastic groups until the ultimate strength was reached and the core suture ruptured. Depending on the suturing method, rigid suture material may not be appropriate for peripheral sutures, when accompanying rigid core suture material. If peripheral sutures can be made with accurate deep holding, rigid suture material will provide favorable outcome. However, in other cases, elastic suture material is considered best for supporting a rigid core suture, as elasticity is another important factor for peripheral sutures. Copyright © 2011 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Camilo Méndez
2014-12-01
Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.
DEFF Research Database (Denmark)
Corry, Olaf; Stevenson, Hayley
2017-01-01
, in the end, one finite interconnected space. Together these two starting points make for the basic conundrum of Inter- national Relations and the Earth: how does a divided world live on a single globe? This introduction first provides an overview of the recent rise of ‘the environment’ in international......, ‘what has the environment ever done for IR?’, before the plan for the rest of the book sketches the content and direction of the ensuing chapters that explore the problematique of International Relations and the Earth....
DEFF Research Database (Denmark)
Kostic, Ana; Sap, Jan; Sheetz, Michael P
2007-01-01
Receptor-like protein tyrosine phosphatase alpha (RPTPalpha)-knockout mice have severe hippocampal abnormalities similar to knockouts of the Src family kinase Fyn. These enzymes are linked to the matrix-rigidity response in fibroblasts, but their function in neurons is unknown. The matrix...... response in hippocampal neuron growth cones, like in fibroblasts. In control neurons, rigid FN surfaces inhibit neurite extension and neuron differentiation relative to soft surfaces. In RPTPalpha(-/-) neurons, no inhibition of extension and differentiation is found on both rigid and soft surfaces...
Multivalent, high-relaxivity MRI contrast agents using rigid cysteine-reactive gadolinium complexes.
Garimella, Praveena D; Datta, Ankona; Romanini, Dante W; Raymond, Kenneth N; Francis, Matthew B
2011-09-21
MRI contrast agents providing very high relaxivity values can be obtained through the attachment of multiple gadolinium(III) complexes to the interior surfaces of genome-free viral capsids. In previous studies, the contrast enhancement was predicted to depend on the rigidity of the linker attaching the MRI agents to the protein surface. To test this hypothesis, a new set of Gd-hydroxypyridonate based MRI agents was prepared and attached to genetically introduced cysteine residues through flexible and rigid linkers. Greater contrast enhancements were seen for MRI agents that were attached via rigid linkers, validating the design concept and outlining a path for future improvements of nanoscale MRI contrast agents.
Maldonado-Codina, Carole; Morgan, Philip B; Efron, Nathan; Efron, Suzanne
2005-06-01
The purpose of this study is to investigate the comparative clinical performance of two hyper Dk contact lenses: a silicone hydrogel lens (Focus Night & Day, Ciba Vision) and a rigid lens (Z-alpha, Menicon Co. Ltd.) when worn for up to 30 days of continuous wear (CW). The rigid lens was worn on an unplanned replacement basis, whereas the soft lens was replaced monthly. One hundred subjects were recruited. Fifty neophyte subjects were randomly assigned into one of the lens types (25 subjects per lens type). Twenty-five existing daily wear (DW) rigid lens users wore the rigid study lens and 25 existing DW soft lens users wore the soft study lens. Visual acuity, lens fit, keratometry, refraction, lens surface assessment, physiological response, and subjective response were investigated at baseline and after 1 week of DW and 24 hours, 1 week, and 1, 3, 6, 9, and 12 months of CW. Analysis compared lens type (rigid vs. soft) and subject group (experienced vs. neophyte). Sixty-eight subjects completed the study. Visual acuity was similar for the two lens types and subject groups. Lens fit was judged to be adequate in all subjects. Corneal curvature of subjects in the rigid groups became flatter by 0.13 mm compared with 0.04 mm for subjects in the soft lens groups (F = 14.7, p = 0.0003); the refractive findings mirrored these corneal changes. The increasing rate of deposition on rigid lenses was consistent with the fact that these lenses were not replaced during the study. Conjunctival hyperemia and staining were similar for the two lens types but greater among experienced wearers at baseline (F = 13.8, p = 0.0005; F = 5.3, p = 0.02, respectively). Corneal staining was higher for the rigid lens wearers (F = 5.6, p = 0.02) but this was mainly the result of the initial higher scores in the rigid lens experienced group. The change in papillary conjunctivitis was greater for subjects in the soft lens groups than rigid lens groups (F = 4.6, p = 0.04). Comfort was initially
Free surface flow of a suspension of rigid particles in a non-Newtonian fluid
DEFF Research Database (Denmark)
Svec, Oldrich; Skocek, Jan; Stang, Henrik
2012-01-01
A numerical framework capable of predicting the free surface flow of a suspension of rigid particles in a non-Newtonian fluid is described. The framework is a combination of the lattice Boltzmann method for fluid flow, the mass tracking algorithm for free surface representation, the immersed...... boundary method for two-way coupled interactions between fluid and rigid particles and an algorithm for the dynamics and mutual interactions of rigid particles. The framework is able to simulate the flow of suspensions at the level of the largest suspended particles and, at the same time, the model is very...
Energy Technology Data Exchange (ETDEWEB)
Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-03-10
When simulating near-surface nuclear detonations, the terrain of the Earth can have an effect on the observed outputs. The critical parameter is called the “height of burst”. In order to model the effect of terrain on the simulations we have incorporated data from multiple sources to give 9 km resolution data with global coverage.
National Aeronautics and Space Administration, Washington, DC.
This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)
Correa, Jose Miguel
2014-01-01
The film "Bones of the Earth" (Riglin, Cunninham & Correa, 2014) is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective…
2002-01-01
This image of Earth's city lights was created with data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth's surface. The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. (Compare western Europe with China and India.) Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of many continents would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. In Russia, the Trans-Siberian railroad is a thin line stretching from Moscow through the center of Asia to Vladivostok. The Nile River, from the Aswan Dam to the Mediterranean Sea, is another bright thread through an otherwise dark region. Even more than 100 years after the invention of the electric light, some regions remain thinly populated and unlit. Antarctica is entirely dark. The interior jungles of Africa and South America are mostly dark, but lights are beginning to appear there. Deserts in Africa, Arabia, Australia, Mongolia, and the United States are poorly lit as well (except along the coast), along with the boreal forests of Canada and Russia, and the great mountains of the Himalaya. The Earth Observatory article Bright Lights, Big City describes how NASA scientists use city light data to map urbanization. Image by Craig Mayhew and Robert Simmon, NASA GSFC, based on DMSP data
Indian Academy of Sciences (India)
wavelength range between 0.2 and 4.0 microns (p,m). ... from the earth is in the long wavelength range from 4.0 to 80/-Lm. .... turing industry. But, it is removed from the atmosphere by the photosynthesis of plants. The largest reservoirs of carbon are in the deep oceans. Some of this reaches the atmosphere when waters.
Pallant, Amy; Lee, Hee-Sun; Pryputniewicz, Sara
2012-01-01
Systems thinking suggests that one can best understand a complex system by studying the interrelationships of its component parts rather than looking at the individual parts in isolation. With ongoing concern about the effects of climate change, using innovative materials to help students understand how Earth's systems connect with each other is…
Understanding Earth's Albedo Effect
Fidler, Chuck
2012-01-01
Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…
Gross, Michael
2015-10-05
Earth is much more complex than all the other solar system objects that we know. Thanks to its rich and diverse geology, our planet can offer habitats to a wide range of living species. Emerging insights suggest that this is not just a happy coincidence, but that life itself has in many ways helped to shape the planet.
Gillette, Brandon; Hamilton, Cheri
2011-01-01
When viewing objects of different colors, you might notice that some appear brighter than others. This is because light is reflected differently from various surfaces, depending on their physical properties. The word "albedo" is used to describe how reflective a surface is. The Earth-atmosphere has a combined albedo of about 30%, a number that is…
Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.
2015-01-01
Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…
DEFF Research Database (Denmark)
Carter, Adrian
2009-01-01
to rescue architecture from the sterile impasse of late-modernism. In his works the basic elements of lived space become present: the earth, the sky and the `between` of human existence." Jørn Utzon's architecture ranges from the modest to the monumental; from the Kingo courtyard houses, the finest...
Magnetic rare earth superlattices
DEFF Research Database (Denmark)
Majkrzak, C.F.; Kwo, J.; Hong, M.
1991-01-01
Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...
A sequence-dependent rigid-base model of DNA.
Gonzalez, O; Petkevičiūtė, D; Maddocks, J H
2013-02-07
A novel hierarchy of coarse-grain, sequence-dependent, rigid-base models of B-form DNA in solution is introduced. The hierarchy depends on both the assumed range of energetic couplings, and the extent of sequence dependence of the model parameters. A significant feature of the models is that they exhibit the phenomenon of frustration: each base cannot simultaneously minimize the energy of all of its interactions. As a consequence, an arbitrary DNA oligomer has an intrinsic or pre-existing stress, with the level of this frustration dependent on the particular sequence of the oligomer. Attention is focussed on the particular model in the hierarchy that has nearest-neighbor interactions and dimer sequence dependence of the model parameters. For a Gaussian version of this model, a complete coarse-grain parameter set is estimated. The parameterized model allows, for an oligomer of arbitrary length and sequence, a simple and explicit construction of an approximation to the configuration-space equilibrium probability density function for the oligomer in solution. The training set leading to the coarse-grain parameter set is itself extracted from a recent and extensive database of a large number of independent, atomic-resolution molecular dynamics (MD) simulations of short DNA oligomers immersed in explicit solvent. The Kullback-Leibler divergence between probability density functions is used to make several quantitative assessments of our nearest-neighbor, dimer-dependent model, which is compared against others in the hierarchy to assess various assumptions pertaining both to the locality of the energetic couplings and to the level of sequence dependence of its parameters. It is also compared directly against all-atom MD simulation to assess its predictive capabilities. The results show that the nearest-neighbor, dimer-dependent model can successfully resolve sequence effects both within and between oligomers. For example, due to the presence of frustration, the model can
Predictors of Difficult Intubation with the Bonfils Rigid Fiberscope.
Nowakowski, Michal; Williams, Stephan; Gallant, Jason; Ruel, Monique; Robitaille, Arnaud
2016-06-01
Endotracheal intubation is commonly performed via direct laryngoscopy (DL). However, in certain patients, DL may be difficult or impossible. The Bonfils Rigid Fiberscope® (BRF) is an alternative intubation device, the design of which raises the question of whether factors that predict difficult DL also predict difficult BRF. We undertook this study to determine which demographic, morphologic, and morphometric factors predict difficult intubation with the BRF. Four hundred adult patients scheduled for elective surgery were recruited. Patients were excluded if awake intubation, rapid sequence induction, or induction without neuromuscular blocking agents was planned. Data were recorded, including age, sex, weight, height, American Society of Anesthesiologist classification, history of snoring and sleep apnea, Mallampati class, upper lip bite test score, interincisor, thyromental and sternothyroid distances, manubriomental distances in flexion and extension, neck circumference, maximal neck flexion and extension, neck skinfold thickness at the cricoid cartilage, and Cormack and Lehane grade obtained via DL after paralysis was confirmed. Quality of glottic visualization (good or poor), as well as the number of intubation attempts and time to successful intubation with the BRF, was noted. Univariate analyses were performed to evaluate the association between patient characteristics and time required for intubation. Variables that exhibited a significant correlation were included in a multivariate analysis using a standard least squares model. A P 1 attempt; 4 patients could not be intubated by using the BRF alone. These 4 patients were intubated by using a combination of DL and BRF (2 patients), DL and a Frova bougie (1 patient), and DL and an endotracheal tube shaped with a semirigid stylet (1 patient). Mean time for successful intubation was 26 ± 13 seconds. Multivariate analysis showed that decreased mouth opening (P = 0.008), increased body mass index (P = 0
PiSQRD: a web server for decomposing proteins into quasi-rigid dynamical domains.
Aleksiev, T; Potestio, R; Pontiggia, F; Cozzini, S; Micheletti, C
2009-10-15
The PiSQRD web resource can be used to subdivide protein structures in quasi-rigid dynamical domains. The latter are groups of amino acids behaving as approximately rigid units in the course of protein equilibrium fluctuations. The PiSQRD server takes as input a biomolecular structure and the desired fraction of protein internal fluctuations that must be accounted for by the relative rigid-body motion of the dynamical domains. Next, the lowest energy modes of fluctuation of the protein (optionally provided by the user) are calculated and used to identify the rigid subunits. The resulting optimal subdivision is returned through a web page containing both interactive graphics and detailed data output. The PiSQRD web server, which requires Java, is available free of charge for academic users at http://pisqrd.escience-lab.org.
Fiber Optic Systems for Light Curing Rigidization of Inflatable Structures Project
National Aeronautics and Space Administration — Light (UV and visible) curing composite matrix resins are being explored as an attractive means for rigidizing inflatable spacecraft for large space-deployed...
Water retention of rigid soils from a two-factor model for clay
Chertkov, V Y
2014-01-01
Water retention is one of the key soil characteristics. Available models of soil water retention relate to the curve-fitting type. The objective of this work is to suggest a physical model of water retention (drying branch) for soils with a rigid matrix. "Physical" means the prediction based on the a priori measured or estimated soil parameters with a clear physical meaning. We rely on the two-factor model of clay that takes into account the factors of capillarity and shrinkage. The key points of the model to be proposed are some weak pseudo shrinkage that the rigid soils demonstrate according to their experimental water retention curves, and some specific properties of the rigid grain matrix. The three input parameters for prediction of soil water retention with the rigid grain matrix include inter-grain porosity, as well as maximum and minimum grain sizes. The comparison between measured and predicted sand water retention curves for four different sands is promising.
A Sensitivity Analysis of the Rigid Pavement Life-Cycle Cost Analysis Program
2000-12-01
Original Report Date: September 1999. This report describes the sensitivity analysis performed on the Rigid Pavement Life-Cycle Cost Analysis program, a computer program developed by the Center for Transportation Research for the Texas Department of ...
NUMERICAL SIMULATIONS FOR THE CASE OF RIGID ROTATING KINEMATIC COUPLING WITH BIG CLEARANCE
Directory of Open Access Journals (Sweden)
Jan-Cristian GRIGORE
2010-10-01
Full Text Available In this paper an algorithm based on [1] [2] are numerical simulations, achieving generalized coordinates of motion, positions, speeds of a rigid rotating kinematic coupling with big clearance in joint, case without friction
An Algorithmic Approach to Wireless Sensor Networks Localization Using Rigid Graphs
Directory of Open Access Journals (Sweden)
Shamantha Rai B
2016-01-01
Full Text Available In this work estimating the position coordinates of Wireless Sensor Network nodes using the concept of rigid graphs is carried out in detail. The range based localization approaches use the distance information measured by the RSSI, which is prone to noise, due to effects of path loss, shadowing, and so forth. In this work, both the distance and the bearing information are used for localization using the trilateration technique. Rigid graph theory is employed to analyze the localizability, that is, whether the nodes of the WSN are uniquely localized. The WSN graph is divided into rigid patches by varying appropriately the communication power range of the WSN nodes and then localizing the patches by trilateration. The main advantage of localizing the network using rigid graph approach is that it overcomes the effect of noisy perturbed distance. Our approach gives a better performance compared to robust quads in terms of percentage of localizable nodes and computational complexity.
Sauvageau, Anny; Kelly, Sean; Ambrosi, Corinne
2012-06-01
The study of filmed hangings in the recent has reveal a striking similarity in the agonal sequences, with a sequence of rapid loss of consciousness, convulsions, and then a complex pattern of decerebrate rigidity and decorticate rigidity. We report a case of filmed hanging not presenting with decerebrate and decorticate rigidity. A 52-year-old man stepped off a stool, hanging himself in a complete suspension in an upright position. The movement of the body stepping off the stool created a rotary movement around the ceiling's ring and the body of the hanging man immediately started to revolve around the ring. Apart for the rolling around the ceiling's ring, the body stayed motionless for the duration of the movie, without any evidence of decerebrate or decorticate rigidity. A review of the pathophysiology of these reflex posturing gives some insight as to the possible elucidation for their absence in this specific case.
Comparison of the effect of semi-rigid ankle bracing on performance ...
African Journals Online (AJOL)
Comparison of the effect of semi-rigid ankle bracing on performance among injured v. non-injured adolescent female hockey players. TJ Ellapen, N Acampora, S Dawson, J Arling, C van Niekerk, HJ van Heerden ...
Level set motion assisted non-rigid 3D image registration
Yang, Deshan; Deasy, Joseph O.; Low, Daniel A.; El Naqa, Issam
2007-03-01
Medical imaging applications of rigid and non-rigid elastic deformable image registration are undergoing wide scale development. Our approach determines image deformation maps through a hierarchical process, from global to local scales. Vemuri (2000) reported a registration method, based on levelset evolution theory, to morph an image along the motion gradient until it deforms to the reference image. We have applied this level set motion method as basis to iteratively compute the incremental motion fields and then we approximated the field using a higher-level affine and non-rigid motion model. In such a way, we combine sequentially the global affine motion, local affine motion and local non-rigid motion. Our method is fully automated, computationally efficient, and is able to detect large deformations if used together with multi-grid approaches, potentially yielding greater registration accuracy.
Anaesthesia and peri-interventional morbidity of rigid bronchoscopy: A retrospective analysis
Directory of Open Access Journals (Sweden)
Jerry Tan
2017-07-01
Conclusion: The choice of anaesthetic technique possibly affects the complication of patients undergoing rigid bronchoscopy. Volatile anaesthetics appeared to be driven by presumably shorter procedure, but was associated with higher systemic complication.
Building America Top Innovations 2013 Profile – Exterior Rigid Insulation Best Practices
Energy Technology Data Exchange (ETDEWEB)
none,
2013-09-01
In this Top Innovation profile, field and lab studies by BSC, PHI, and NorthernSTAR characterize the thermal, air, and vapor resistance properties of rigid foam insulation and describe best practices for their use on walls, roofs, and foundations.
Semi-rigid brace and taping decrease variability of the ankle joint position sense
Directory of Open Access Journals (Sweden)
Márcia Barbanera
2014-12-01
Full Text Available The present study investigated the effect of taping and the semi-rigid ankle brace on ankle joint position sense. Sixteen healthy women (20.8 ± 2.3 years old actively placed the ankle in a target position. The experimental conditions were: 1 wearing no orthosis device, 2 using semi-rigid brace, and 3 wearing ankle taping. Absolute error (AE and variable error (VE were calculated to obtain the joint position sense. We found an interaction effect between condition and target angle at 15o of plantar flexion for the variable VE, which showed smaller errors during the use of taping and semi-rigid brace. In conclusion, the use of ankle joint orthoses, whether taping or semi-rigid brace, decrease the variability of the position sense at 15o of plantar flexion, potentially decreasing ankle sprains occurrence.
Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles
Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.
2011-01-01
Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.
Convergent Synthesis of Rigid Macrocycles Containing One and Two Tetrathiafulvalene Units
DEFF Research Database (Denmark)
Simonsen, Klaus B.; Thorup, Niels; Becher, Jan
1997-01-01
The synthesis of rigid tetrathiafulvalenophanes containing one or two tetrathiafulvalene units is presented, together with a stepwise convergent synthesis of macrocyclic bis-tetrathiafulvalenes via several open dimeric tetrathiafulvalenes. These systems were investigated by cyclic voltammetry...
Positive semidefinite matrix completion, universal rigidity and the Strong Arnold Property
M. Laurent (Monique); A. Varvitsiotis (Antonios)
2014-01-01
htmlabstractThis paper addresses the following three topics: positive semidefinite (psd) matrix completions, universal rigidity of frameworks, and the Strong Arnold Property (SAP). We show some strong connections among these topics, using semidefinite programming as unifying theme. Our main
Positive semidefinite matrix completion, universal rigidity and the Strong Arnold Property
M. Laurent (Monique); A. Varvitsiotis (Antonios)
2013-01-01
htmlabstractThis paper addresses the following three topics: positive semidefinite (psd) matrix completions, universal rigidity of frameworks, and the Strong Arnold Property (SAP). We show some strong connections among these topics, using semidefinite programming as unifying theme. Our main
Market structure, price rigidity, and performance in the Indonesian food and beverages industry
Setiawan, M.
2012-01-01
Keywords: industrial concentration, price rigidity, technical efficiency, price-cost margin, Structure-Conduct-Performance (SCP), new empirical industrial organization (NEIO), Indonesian food and beverages industry, Data Envelopment Analysis (DEA), system of equations The
He, Daping; He, Dong Sheng; Yang, Jinlong; Low, Ze-Xian; Malpass-Evans, Richard; Carta, Mariolino; McKeown, Neil B; Marken, Frank
2016-08-31
A molecularly rigid polyamine based on a polymer of intrinsic microporosity (PIM-EA-TB) is shown to capture and stabilize platinum nanoparticles during colloid synthesis in the rigid framework. Stabilization here refers to avoiding aggregation without loss of surface reactivity. In the resulting rigid framework with embedded platinum nanoparticles, the volume ratio of platinum to PIM-EA-TB in starting materials is varied systematically from approximately 1.0 to 0.1 with the resulting platinum nanoparticle diameter varying from approximately 4.2 to 3.1 nm, respectively. Elemental analysis suggests that only a fraction of the polymer is "captured" to give nanocomposites rich in platinum. A transition occurs from electrically conducting and electrochemically active (with shorter average interparticle distance) to nonconducting and only partially electrochemically active (with longer average interparticle distance) polymer-platinum composites. The conducting nanoparticle network in the porous rigid macromolecular framework could be beneficial in electrocatalysis and in sensing applications.
Correlation of impression removal force with elastomeric impression material rigidity and hardness.
Walker, Mary P; Alderman, Nick; Petrie, Cynthia S; Melander, Jennifer; McGuire, Jacob
2013-07-01
Difficult impression removal has been linked to high rigidity and hardness of elastomeric impression materials. In response to this concern, manufacturers have reformulated their materials to reduce rigidity and hardness to decrease removal difficulty; however, the relationship between impression removal and rigidity or hardness has not been evaluated. The purpose of this study was to determine if there is a positive correlation between impression removal difficulty and rigidity or hardness of current elastomeric impression materials. Light- and medium-body polyether (PE), vinylpolysiloxane (VPS), and hybrid vinyl polyether siloxane (VPES) impression materials were tested (n = 5 for each material/consistency/test method). Rigidity (elastic modulus) was measured via tensile testing of dumbbell-shaped specimens (Die C, ASTM D412). Shore A hardness was measured using disc specimens according to ASTM D2240-05 test specifications. Impressions were also made of a custom stainless steel model using a custom metal tray that could be attached to a universal tester to measure associated removal force. Within each impression material consistency, one-factor ANOVA and Tukey's post hoc analyses (α = 0.05) were used to compare rigidity, hardness, and removal force of the three types of impression materials. A Pearson's correlation (α = 0.05) was used to evaluate the association between impression removal force and rigidity or hardness. With medium-body materials, VPS exhibited significantly higher (p ≤ 0.05) rigidity and hardness than VPES or PE, while PE impressions required significantly higher (p ≤ 0.05) removal force than VPS or VPES impressions. With light-body materials, VPS again demonstrated significantly higher (p ≤ 0.05) hardness than VPES or PE, while the rigidity of the light-body materials did not significantly differ between materials (p > 0.05); however, just as with the medium-body materials, light-body PE impressions required significantly higher (p
Evaluation of surgical performance with standard rigid and flexible-tip laparoscopes.
Perrone, J M; Ames, C D; Yan, Y; Landman, J
2005-10-01
Flexible-tip laparoscopes have recently been introduced into clinical practice, with the goal of improving surgeon performance during complex laparoscopic procedures. We used objective and subjective performance parameters to compare standard rigid 0 degrees and 30 degrees lens laparoscopes two flexible-tip laparoscopes in an in vitro model. Twenty-nine subjects with varied levels of surgical experience performed complex laparoscopic tasks in three different models simulating (a) prostate dissection from the rectum, (b) cystic duct clipping, and (c) distal posterior rectum dissection. Each task was performed using two Storz rigid laparoscopes (0 degrees and 30 degrees) and two flexible-tip laparoscopes, the Olympus LTF-V3 and the Fujinon EL2-TF310. The sequence of application of the two flexible-tip laparoscopes was randomized. In each case, an experienced laparoscopic camera driver controlled the field of vision. Time to complete each task, operative precision, and subjective surgeon rating scores were compared. Statistical analysis was performed with analysis of variance (ANOVA) and a two-sided fisher's exact test. In all three models, the flexible laparoscopes offered no advantage in terms of procedure time, surgical precision, or subjective surgeon rating score when compared with the 30 degrees lens rigid laparoscope. The 30 degrees rigid lens laparoscope and the two flexible-tip laparoscopes were superior to the 0 degrees lens rigid laparoscope for all parameters evaluated, with the exception of subjective rating in the cystic duct model and procedure time in the colorectal model. In this in vitro experimental model, the flexible-tip laparoscopes found to have no advantage over the standard rigid 30 degrees lens laparoscope. These models were validated, as the 0 degrees lens rigid laparoscope was surpassed by the 30 degrees lens rigid laparoscope and the flexible-tip laparoscopes. Both flexible-tip laparoscopes produced similar results and excellent image
Precast Slabs for Contingency Rigid Airfield Pavement Damage Repairs (BRIEFING SLIDES)
2010-04-01
efficiency of using different precast concrete panel installation techniques for contingency repair of damaged airfield pavements . Fast-setting polymer ...AFRL-RX-TY-TP-2010-0055 PRECAST SLABS FOR CONTINGENCY RIGID AIRFIELD PAVEMENT DAMAGE REPAIRS (BRIEFING SLIDES) Reza Ashtiani Applied...Rigid Airfield Pavement Damage Repairs (BRIEFING SLIDES) FA4819-09-C-0028 62102F 4915 D1 4915D14E Ashtiani, Reza; *Hammons, Michael I. Applied Research
Contact point generation for convex polytopes in interactive rigid body dynamics
DEFF Research Database (Denmark)
Silcowitz-Hansen, Morten; Abel, Sarah Maria Niebe; Erleben, Kenny
When computing contact forces in rigid body dynamics systems, most state-of-the-art solutions use iterative methods such as the projected Gauss–Seidel (PGS) method. Methods such as the PGS method are preferred for their robustness. However, the time-critical nature of interactive applications...... for convex polytopes. A novel contact point generation method is presented, which is based on growth distances and Gauss maps. We demonstrate improvements when using our method in the context of interactive rigid body simulation...
Pre-Cast Concrete Panels for Contingency Rigid Airfield Pavement Damage Repairs
2010-06-01
Micro- texture of the particle plays an important role in aggregate interlock. Therefore, mixes consisting of less polished aggregates are expected to...AFRL-RX-TY-TR-2010-0095 PRECAST CONCRETE PANELS FOR CONTINGENCY RIGID AIRFIELD PAVEMENT DAMAGE REPAIRS Reza S. Ashtiani, Christopher J...Final Technical Report 01-JAN-2008 -- 30-APR-2010 Pre-Cast Concrete Panels for Rapid Repair of Airfield Rigid Pavements FA4819-09-C-0028 62102F 4915 D1
Analysis of viscoelastic properties of wrist joint for quantification of parkinsonian rigidity.
Park, Byung Kyu; Kwon, Yuri; Kim, Ji-Won; Lee, Jae-Ho; Eom, Gwang-Moon; Koh, Seong-Beom; Jun, Jae-Hoon; Hong, Junghwa
2011-04-01
This study aims to analyze viscoelastic properties of the wrist in patients with Parkinson's disease (PD) in comparison with the clinical score of severity. Forty-five patients with PD and 12 healthy volunteers participated in this study. Severity of rigidity at the wrist was rated by a neurologist just before the experiment. Wrist joint torque resistive to the imposed movement was measured. Three different models, (identical in structure, only different in the number of parameters for extension and flexion phases) were used in identification of viscoelastic properties: 1) one damping constant and one spring constant throughout all phases, 2) two damping constants for each phase and one spring constant throughout all phases, and 3) two damping constants and two spring constants for each phase. Normalized work and impulse suggested in the literature were also calculated. Spring constants of different models and phases showed comparable correlation with rigidity score ( r=0.68-0.73). In terms of the correlation of damping constant with clinical rigidity score, model 1 ( r = 0.90) was better than models 2 and 3 ( r=0.59 - 0.71). These results suggest that the clinical rigidity score is better represented by the mean viscosity during both flexion and extension. In models with two dampers (model 2 and 3), the damping constant was greater during extension than flexion in patients , in contrast that there was no phase difference in normal subjects. This suggests that in contrast with normal subjects, phase-dependent viscosity may be an inherent feature of PD. Although work and impulse were correlated with clinical rigidity score ( r = 0.11 - 0.84), they could not represent the phase-dependent rigidity inherent in PD. In conclusion, the viscosity of model 1 would be appropriate for quantification of clinical ratings of rigidity and that of model 2 for distinction of PD and also for investigation of phase-dependent characteristics in parkinsonian rigidity.
The Serret-Andoyer Formalism in Rigid-Body Dynamics: I. Symmetries and Perturbations
Gurfil, Pini; Elipe, Antonio; Tangren, William; Efroimsky, Michael
2006-01-01
This paper reviews the Serret-Andoyer (SA) canonical formalism in rigid-body dynamics and presents some new results. As is well known, the problem of unsupported and unperturbed rigid rotator can be reduced. The availability of this reduction is offered by the underlying symmetry, which stems from conservation of the angular momentum and rotational kinetic energy. When a perturbation is turned on, these quantities are no longer preserved. Nonetheless, the language of reduced description remai...
Eman A. Embaby; Eman M.A. Abdalgwad
2016-01-01
Background: Rigid and kinesio taping is commonly used in the rehabilitation and prevention of subacromial impingement syndrome (SIS). It is proposed to have positive effects on shoulder function and scapular kinematics. However, there is a paucity of literature regarding the effectiveness of rigid versus elastic taping on scapular upward rotation and forward head posture (FHP), which is commonly adopted in SIS. Purpose: This study was designed to investigate the effect of taping with post...
Page 1 Rigidity problem for lattices in solvable Lie groups 513 . in ...
Indian Academy of Sciences (India)
º f i.1 º group as a lattice. Now we may give an example of a rigid lattice T in olvable Lie group G of (I)-type. This lattice will be constructed with the help of a weakly rigid lattice in a splittable Lie. £º. : ~! ~1?? 1 - 4.4.2 group of (I)-type fro. Superrigid” lattice from the corollary above. (I)-type from example 2.8 and a. Example 8.3.
ANALYTIC EVALUATION OF RECTILINEARITY OF LOW RIGIDITY SHAFT DURING HARDENING PROCESS
Directory of Open Access Journals (Sweden)
Antoni Świć
2013-03-01
Full Text Available The essential influence of the unevenness of temperature distribution while heating in the technological process on dimensions stability of low rigidity elements was shown. The new approach was applied to formulate mathematical models, which describe the elastic and inelastic behaviour of piece using transfer functions and block diagrams, allowing to use frequency method for evaluation of the behaviour of dynamic semi-finished element as the rigid body.
Comparison and Implementation of a Rigid and a Flexible Multibody Planetary Gearbox Model
DEFF Research Database (Denmark)
Jørgensen, Martin Felix; Pedersen, Niels Leergaard; Sørensen, Jens Nørkær
2014-01-01
We propose algorithms for developing (1) a rigid (constrained) and (2) a flexible planetary gearbox model. The two methods are compared against each other and advantages/disadvantages of each method are discussed. The rigid model (1) has gear tooth reaction forces expressed by Lagrange multipliers...... between one and two gear teeth in mesh. The final results are from modelling the planetary gearbox in a 500 kW wind turbine which we also described in Jørgensen et al. (2013)....
Cashman, K. V.; Rust, A.; Stibbon, E.; Harris, R.
2016-12-01
Earth materials are fundamental to art. They are pigments, they are clay, they provide form and color. Earth scientists, however, rarely attempt to make the physical properties of Earth materials visible through art, and similarly many artists use Earth materials without fully understanding their physical and chemical properties. Here we explore the intersection between art and science through study of the physical properties of Earth materials as characterized in the laboratory, and as transferred to paper using different techniques and suspending media. One focus of this collaboration is volcanic ash. Ash is interesting scientifically because its form provides information on the fundamental processes that drive volcanic eruptions, and determines its transport properties, and thus its potential to affect populations far downwind of the volcano. Ash properties also affect its behavior as an art material. From an aesthetic point of view, ash lends a granular surface to the image; it is also uncontrollable, and thus requires engagement between artist and medium. More fundamentally, using ash in art creates an exchange between the medium and the subject matter, and imparts something of the physical, visceral experience of volcanic landscapes to the viewer. Another component of this work uses powdered rock as a printing medium for geologic maps. Because different types of rock create powders with different properties (grain size distributions and shapes), the geology is communicated not only as color, but also by the physical characteristics of the material as it interacts with the paper. More importantly, the use of actual rocks samples as printing material for geologic maps not only makes a direct connection between the map and the material it represents, but also provides an emotional connection between the map, the viewer and the landscape, its colors, textures and geological juxtapositions. Both case studies provide examples not only of ways in which artists can
Earth Science Multimedia Theater
Hasler, A. F.
1998-01-01
The presentation will begin with the latest 1998 NASA Earth Science Vision for the next 25 years. A compilation of the 10 days of animations of Hurricane Georges which were supplied daily on NASA to Network television will be shown. NASA's visualizations of Hurricane Bonnie which appeared in the Sept 7 1998 issue of TIME magazine. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1 -min GOES images that will appear in the October BAMS. The visualizations are produced by the Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the "Digital-HyperRes-Panorama" Earth Science ETheater'98 recently presented in Tokyo, Paris and Phoenix. The presentation in Paris used a SGI/CRAY Onyx Infinite Reality Super Graphics Workstation at 2560 X 1024 resolution with dual synchronized video Epson 71 00 projectors on a 20ft wide screen. Earth Science Electronic Theater '999 is being prepared for a December 1 st showing at NASA HQ in Washington and January presentation at the AMS meetings in Dallas. The 1999 version of the Etheater will be triple wide with at resolution of 3840 X 1024 on a 60 ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense Hyperimage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites
Technical Note: Semi-rigid chambers for methane gas flux measurements on tree-stems
Siegenthaler, A.; Welch, B.; Pangala, S. R.; Peacock, M.; Gauci, V.
2015-09-01
There is increasing interest in the measurement of methane (CH4) emissions from tree stems in a wide range of ecosystems so as to determine how they contribute to the total ecosystem flux. To date, tree CH4 fluxes are commonly measured using rigid closed chambers (static or dynamic), which often pose challenges as these are bulky and limit measurement of CH4 fluxes to only a very narrow range of tree stem sizes and shapes. To overcome these challenges we aimed to design, describe and test new semi-rigid stem-flux chambers (or sleeves). We compared semi-rigid chamber's gas permeability to CH4 against the traditional rigid chamber approach, in the laboratory and in the field, with continuous flow or syringe injections. We found that the semi-rigid chambers performed well, and had numerous benefits including reduced gas permeability and optimal stem gas exchange surface to total chamber volume ratio (Sc/Vtot) allowing better headspace mixing, especially when connected in a dynamic mode to a continuous flow gas analyser. Semi-rigid sleeves can easily be constructed and transported in multiple sizes, are extremely light, cheap to build and fast to deploy. This makes them ideal for use in remote ecosystems where access logistics are complicated.
Numerical Simulation of Dry Granular Flow Impacting a Rigid Wall Using the Discrete Element Method.
Wu, Fengyuan; Fan, Yunyun; Liang, Li; Wang, Chao
2016-01-01
This paper presents a clump model based on Discrete Element Method. The clump model was more close to the real particle than a spherical particle. Numerical simulations of several tests of dry granular flow impacting a rigid wall flowing in an inclined chute have been achieved. Five clump models with different sphericity have been used in the simulations. By comparing the simulation results with the experimental results of normal force on the rigid wall, a clump model with better sphericity was selected to complete the following numerical simulation analysis and discussion. The calculation results of normal force showed good agreement with the experimental results, which verify the effectiveness of the clump model. Then, total normal force and bending moment of the rigid wall and motion process of the granular flow were further analyzed. Finally, comparison analysis of the numerical simulations using the clump model with different grain composition was obtained. By observing normal force on the rigid wall and distribution of particle size at the front of the rigid wall at the final state, the effect of grain composition on the force of the rigid wall has been revealed. It mainly showed that, with the increase of the particle size, the peak force at the retaining wall also increase. The result can provide a basis for the research of relevant disaster and the design of protective structures.
May 2005 Halo CMEs and Galactic Cosmic Ray Flux Changes at Earth's Orbit
Ahluwalia, H. S.; Alania, M. V.; Wawrzynczak, A.; Ygbuhay, R. C.; Fikani, M. M.
2014-05-01
The pressure corrected hourly data from the global network of cosmic ray detectors, measurements of the interplanetary magnetic field (IMF) intensity ( B) at Earth's orbit and its components B x , B y , B z (in the geocentric solar ecliptic coordinates) are used to conduct a comprehensive study of the galactic cosmic ray (GCR) intensity fluctuations caused by the halo coronal mass ejection of 13 May 2005. Distinct differences exist in GCR timelines recorded by neutron monitors (NMs) and multidirectional muon telescopes (MTs), the latter respond to the high rigidity portion of the GCR differential rigidity spectrum. The Forbush decrease (FD) onset in MTs is delayed (˜5 h) with respect to the onset of a geomagnetic storm sudden commencement (SSC) and a large pre-increase is present in MT data before, during, and after the SSC onset, of unknown origin. The rigidity spectrum, for a range of GCR rigidities (≤200 GV), is a power law in rigidity (R) with a negative exponent ( γ=-1.05) at GCR minimum intensity, leading us to infer that the quasi-linear theory of modulation is inconsistent with observations at high rigidities (>1 GV); the results support the force field theory of modulation. At present, we do not have a comprehensive model for the FD explaining quantitatively all the observational features but we present a preliminary model listing physical processes that may contribute to a FD timeline. We explored the connections between different phases of the FD and the power spectra of IMF components but did not find a sustained relationship.
van der Put, R. W.; Kerkhof, E. M.; Raaymakers, B. W.; Jürgenliemk-Schulz, I. M.; Lagendijk, J. J. W.
2009-12-01
External beam radiation treatment for patients with cervical cancer is hindered by the relatively large motion of the target volume. A hybrid MRI-accelerator system makes it possible to acquire online MR images during treatment in order to correct for motion and deformation. To fully benefit from such a system, online delineation of the target volumes is necessary. The aim of this study is to investigate the accuracy of rigid, non-rigid and semi-automatic registrations of MR images for interfractional contour propagation in patients with cervical cancer. Registration using mutual information was performed on both bony anatomy and soft tissue. A B-spline transform was used for the non-rigid method. Semi-automatic registration was implemented with a point set registration algorithm on a small set of manual landmarks. Online registration was simulated by application of each method to four weekly MRI scans for each of 33 cervical cancer patients. Evaluation was performed by distance analysis with respect to manual delineations. The results show that soft-tissue registration significantly (P cervical cancer, online MRI imaging will allow target localization based on soft tissue visualization, which provides a significantly higher accuracy than localization based on bony anatomy. The use of limited user input to guide the registration increases overall accuracy. Additional non-rigid registration further reduces the propagation error and negates errors caused by small observer variations.
Inaugeral lecture - Meteorite impacts on Earth and on the Earth ...
African Journals Online (AJOL)
There is some controversial evidence for the theory that the first life on Earth itself may have been transported here on meteorites from Mars. The possibility of a major meteorite impact on Earth in the near future emphasizes the dramatic nature of these recent discoveries, which are having deep impacts in the Earth sciences ...
Towards earth AntineutRino TomograpHy (EARTH)
De Meijer, R. J.; Smit, F. D.; Brooks, F. D.; Fearick, R. W.; Wortche, H. J.; Mantovani, F.
2006-01-01
The programme Earth AntineutRino TomograpHy (EARTH) proposes to build ten underground facilities each hosting a telescope. Each telescope consists of many detector modules, to map the radiogenic heat sources deep in the interior of the Earth by utilising direction sensitive geoneutrino detection.
Directory of Open Access Journals (Sweden)
John A. Onofrey
2016-01-01
Full Text Available This paper describes a framework for learning a statistical model of non-rigid deformations induced by interventional procedures. We make use of this learned model to perform constrained non-rigid registration of pre-procedural and post-procedural imaging. We demonstrate results applying this framework to non-rigidly register post-surgical computed tomography (CT brain images to pre-surgical magnetic resonance images (MRIs of epilepsy patients who had intra-cranial electroencephalography electrodes surgically implanted. Deformations caused by this surgical procedure, imaging artifacts caused by the electrodes, and the use of multi-modal imaging data make non-rigid registration challenging. Our results show that the use of our proposed framework to constrain the non-rigid registration process results in significantly improved and more robust registration performance compared to using standard rigid and non-rigid registration methods.
Jewitt, David
2017-08-01
Planet-crossing asteroid (3200) Phaethon, source of the Geminid meteoroid stream, will pass close to Earth in December 2017. Observations with HST are proposed to image debris ejected from this object at 1 AU heliocentric distance, to estimate the ejection velocities as the Earth passes through the orbit plane, and to estimate the dust production rate for comparison with the rates needed to sustain the Geminid stream in steady-state. These measurements will help determine the mechanism behind the ejection of the Geminids, a long-standing puzzle. While the release of micron-sized particles (probably by thermal fracture) has been recorded at Phaethon's perihelion (0.14 AU), mass loss has never been detected otherwise, raising the puzzle of the ejection mechanism and duration. The close approach (0.07 AU) on December 17 gives a once-in-a-lifetime opportunity to observe Phaethon at high sensitivity with a resolution of a few kilometers.
Marketing Earth science education
Snieder, Roel; Spiers, Chris
In the 1990s, the Department of Earth Sciences at Utrecht University in the Netherlands was struggling with a declining influx of students. For years, the department had been active in promoting its program, but this was insufficient to stem the decline in interest. To remedy the problem, the school's Earth science faculty carried out, with the help of consultants, a qualitative evaluation of its promotional activities. The faculty feared that their own image of the department might be in conflict with the image held by others; prospective students, in particular. The consultants interviewed secondary school students, parents, teachers, and study advisors in secondary schools. This article is a report on the results of this evaluation.
Sharov, Alexei A
2013-01-01
An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes. Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago. This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no...
Book Review: Precession, Nutation, and Wobble of the Earth
Sterken, Christiaan; Dehant, V.; Mathews, P. M.
2016-10-01
This great book describes and explains observational and computational aspects of three apparently tiny changes in the Earth's motion and orientation, viz., precession, nutation, and wobble. The three introductory chapters of this book present fundamental definitions, elementary geodetic theory, and celestial/terrestrial reference systems - including transformations between reference frames. The next chapter on observational techniques describes the principle of accurate measurements of the orientation of the Earth's axis, as obtained from measurements of extra-galactic radio sources using Very Long Baseline Interferometry and GPS observations. Chapter 5 handles precession and nutation of the rigid Earth (i.e., a celestial body that cannot, by definition, deform) and the subsequent chapter takes deformation into consideration, viz., the effect of a centrifugal force caused by a constant-rate rotation that causes the Earth's shape and structure to become ellipsoidal. Deformations caused by external solar-system bodies are discussed in terms of deformability parameters. The next three chapters handle additional complex deviations: non-rigid Earth and more general Earth models, anelastic Earth parameters, and the effects of the fluid layers (i.e., ocean and atmosphere) on Earth rotation. Chapter 10 complements Chapter 7 with refinements that take into account diverse small effects such as the effect of a thermal conductive layer at the top of the core, Core Mantle and Inner Boundary coupling effects on nutation, electromagnetic coupling, and so-called topographic coupling. Chapter 11 covers comparison of observation and theory, and tells us that the present-date precision of the nutation theory is at the level of milliarcseconds in the time domain, and of a tenth of a microsecond in the frequency domain (with some exceptions). This chapter is followed by a 25-page chapter of definitions of equator, equinox, celestial intermediate pole and origin, stellar angle
Witzberger, Kevin (Inventor); Hojnicki, Jeffery (Inventor); Manzella, David (Inventor)
2016-01-01
Modeling and control software that integrates the complexities of solar array models, a space environment, and an electric propulsion system into a rigid body vehicle simulation and control model is provided. A rigid body vehicle simulation of a solar electric propulsion (SEP) vehicle may be created using at least one solar array model, at least one model of a space environment, and at least one model of a SEP propulsion system. Power availability and thrust profiles may be determined based on the rigid body vehicle simulation as the SEP vehicle transitions from a low Earth orbit (LEO) to a higher orbit or trajectory. The power availability and thrust profiles may be displayed such that a user can use the displayed power availability and thrust profiles to determine design parameters for an SEP vehicle mission.
Photosynthesis and early Earth.
Shih, Patrick M
2015-10-05
Life has been built on the evolution and innovation of microbial metabolisms. Even with our scant understanding of the full diversity of microbial life, it is clear that microbes have become integral components of the biogeochemical cycles that drive our planet. The antiquity of life further suggests that various microbial metabolisms have been core and essential to global elemental cycling for a majority of Earth's history. Copyright © 2015 Elsevier Ltd. All rights reserved.
Earth Abides Arsenic Biotransformations
Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.
2014-01-01
Arsenic is the most prevalent environmental toxic element and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of Earth and the evolution of life, and the connection between arsenic geochemistry and biology ...
Superhydrophobic diatomaceous earth
Simpson, John T [Clinton, TN; D& #x27; Urso, Brian R [Clinton, TN
2012-07-10
A superhydrophobic powder is prepared by coating diatomaceous earth (DE) with a hydrophobic coating on the particle surface such that the coating conforms to the topography of the DE particles. The hydrophobic coating can be a self assembly monolayer of a perfluorinated silane coupling agent. The DE is preferably natural-grade DE where organic impurities have been removed. The superhydrophobic powder can be applied as a suspension in a binder solution to a substrate to produce a superhydrophobic surface on the substrate.
Sharov, Alexei A; Gordon, Richard
2013-01-01
An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization,...
Ignatiev, A Yu
2014-01-01
MOND is one of the most popular alternatives to Dark Matter (DM). While efforts to directly detect DM in laboratories have been steadily pursued over the years, the proposed Earth-based tests of MOND are still in their infancy. Some proposals recently appeared in the literature are briefly reviewed, and it is argued that collaborative efforts of theorists and experimenters are needed to move forward in this exciting new area. Possible future directions are outlined.
Earth's heat budget: Clairvoyant geoneutrinos
Korenaga, Jun
2011-09-01
The quantity of heat generated by radioactive decay in Earth's interior is controversial. Measurements of geoneutrinos emitted from the mantle during this decay indicate that this source contributes only about half of Earth's total outgoing heat flux.
Physics: clairvoyant of the Earth
Haworth, R. T.
1991-05-01
The Earth is a vibrant body whose structure and dynamics can be investigated by geophysics. Earth movements not only constitute a hazard, but over many millenia have contributed to the development and location of our natural resources.
Mirador - Earth Surface and Interior
National Aeronautics and Space Administration — Earth Science data access made simple. The goal of the Earth Surface and Interior focus area is to assess, mitigate and forecast the natural hazards that affect...
Lang, Kenneth R
2006-01-01
This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...
Directory of Open Access Journals (Sweden)
Valencia D.
2011-02-01
Full Text Available The era of Super-Earths has formally begun with the detection of transiting low-mass exoplanets CoRoT-7b and GJ 1214b. In the path of characterising super-Earths, the ﬁrst step is to infer their composition. While the discovery data for CoRoT-7b, in combination with the high atmospheric mass loss rate inferred from the high insolation, suggested that it was a rocky planet, the new proposed mass values have widened the possibilities. The combined mass range 1−10 M⊕ allows for a volatile-rich (and requires it if the mass is less than 4 M⊕ , an Earth-like or a super-Mercury-like composition. In contrast, the radius of GJ 1214b is too large to admit a solid composition, thus it necessarily to have a substantial gas layer. Some evidence suggests that within this gas layer H/He is a small but non-negligible component. These two planets are the ﬁrst of many transiting low-mass exoplanets expected to be detected and they exemplify the limitations faced when inferring composition, which come from the degenerate character of the problem and the large error bars in the data.
Directory of Open Access Journals (Sweden)
Emilian M. Dobrescu
2013-05-01
Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.
Tsaousoglou, Phoebus; Michalakis, Konstantinos; Kang, Kiho; Weber, Hans-Peter; Sculean, Anton
2017-07-01
To assess survival, as well as technical and biological complication rates of partial fixed dental prostheses (FDPs) supported by implants and teeth. An electronic Medline search was conducted to identify articles, published in dental journals from January 1980 to August 2015, reporting on partial FDPs supported by implants and teeth. The search terms were categorized into four groups comprising the PICO question. Manual searches of published full-text articles and related reviews were also performed. The initial database search produced 3587 relevant titles. Three hundred and eighty-six articles were retrieved for abstract review, while 39 articles were selected for full-text review. A total of 10 studies were selected for inclusion. Overall survival rate for implants ranged between 90% and 100%, after follow-up periods with a mean range of 18-120 months. The survival of the abutment teeth was 94.1-100%, while the prostheses survival was 85-100% for the same time period. The most frequent complications were "periapical lesions" (11.53%). The most frequent technical complication was "porcelain occlusal fracture" (16.6%), followed by "screw loosening" (15%). According to the meta-analysis, no intrusion was noted on the rigid connection group, while five teeth (8.19%) were intruded in the non-rigid connection group [95% CI (0.013-0.151)]. The tooth-implant FDP seems to be a possible alternative to an implant-supported FDP. There is limited evidence that rigid connection between teeth and implants presents better results when compared with the non-rigid one. The major drawback of non-rigidly connected FDPs is tooth intrusion. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Rigidity and definition of Caribbean plate motion from COCONet and campaign GPS observations
Mattioli, Glen; Miller, Jamie; DeMets, Charles; Jansma, Pamela
2014-05-01
The currently accepted kinematic model of the Caribbean plate presented by DeMets et al. (2007) is based on velocities from 6 continuous and 14 campaign GPS sites. COCONet is a multi-hazard GPS-Met observatory, which extends the existing infrastructure of the Plate Boundary Observatory in North America into the Caribbean basin. In 2010, UNAVCO in collaboration with UCAR, was funded by NSF to design, build, and initially maintain a network of 50 new cGPS/Met sites and include data from another 50 existing sites in the Caribbean region. The current COCONet siting plan calls for 46 new stations, 21 refurbished stations, and 77 existing stations across 26 nations in the Caribbean region. Data from all COCONet sites flow into the UNAVCO archive and are processed by the PBO analysis centers and are also processed independently by the UTA Geodesy Lab using GIPSY-OASISII (v.6.2) using an absolute point positioning strategy and final, precise orbits, clocks, and Earth orientation parameters from JPL in the IGS08 frame. We present here our refined estimate of Caribbean plate motion by evaluating data from an expanded number of stations with an improved spatial distribution. In order to better constrain the eastern margin of the plate near the Lesser Antilles subduction interface, campaign GPS observations have been collected on the island of Dominica over the last decade. These are combined with additional campaign observations from the western Caribbean, specifically from Honduras and Nicaragua. We have analyzed a total of 117 sites from the Caribbean region, including campaign data and the data from the cGPS stations that comprise COCONet. An updated velocity field for the Caribbean plate is presented and an inversion of the velocities for 24 sites yields a plate angular velocity that differs from previously published models. Our best fitting inversion to GPS velocities from these 24 sites suggests that 2-plate model for the Caribbean is required to fit the GPS
Evaluation of Rigid Cochlear Models for Measuring Cochlear Implant Electrode Position.
Cakir, Ahmet; Labadie, Robert F; Zuniga, M Geraldine; Dawant, Benoit M; Noble, Jack H
2016-12-01
To investigate the accuracy of rigid cochlear models in measuring intra-cochlear positions of cochlear implant (CI) electrodes. Ninety three adults who had undergone CI and pre- and postoperative computed tomographic (CT) imaging. Seven rigid models of cochlear anatomy were constructed using micro-CTs of cochlear specimens. Using each of the seven models, the position of each electrode in each of the 98 ears in our dataset was measured as its depth along the length of the cochlea, its distance to the basilar membrane, and its distance to the modiolus. Cochlear duct length was also measured using each model. Standard deviation (SD) across rigid cochlear models in measures of electrode depth, distance to basilar membrane, distance to modiolus, and length of the cochlear duct at two turns were 0.68, 0.11, 0.15, and 1.54 mm. Comparing the estimated position of the electrodes with respect to the basilar membrane, i.e., deciding whether an electrode was located within the scala tympani (ST) or the scala vestibuli (SV), there was not a unanimous agreement between the models for 19% of all the electrodes. With respect to the modiolus, each electrode was classified into one of the three groups depending on its modiolar distance: close, medium, and far. Rigid models did not unanimously agree on modiolar distance for approximately 50% of the electrodes tested. Inter-model variance of rigid cochlear models exists, demonstrating that measurements made using rigid cochlear models are limited in terms of accuracy because of non-rigid inter-subject variations in cochlear anatomy.
Ignasiak, Dominika; Ferguson, Stephen J; Arjmand, Navid
2016-09-06
A number of musculoskeletal models of the human spine have been used for predictions of lumbar and muscle forces. However, the predictive power of these models might be limited by a commonly made assumption; thoracic region is represented as a single lumped rigid body. This study hence aims to investigate the impact of such assumption on the predictions of spinal and muscle forces. A validated thoracolumbar spine model was used with a flexible thorax (T1-T12), a completely rigid one or rigid with thoracic posture updated at each analysis step. The simulations of isometric forward flexion up to 80°, with and without a 20kg hand load, were performed, based on the previously measured kinematics. Depending on the simulated task, the rigid model predicted slightly or moderately lower compressive loading than the flexible one. The differences were relatively greater at the upper lumbar levels (average underestimation of 14% at the T12L1 for flexion tasks and of 18% for flexion tasks with hand load) as compared to the lower levels (3% and 8% at the L5S1 for unloaded and loaded tasks, respectively). The rigid model with updated thoracic posture predicted compressive forces similar to those of the rigid model. Predicted muscle forces were, however, very different between the three models. This study indicates that the lumbar spine models with a rigid thorax definition can be used for loading investigations at the lowermost spinal levels. For predictions of upper lumbar spine loading, using models with an articulated thorax is advised. Copyright © 2016 Elsevier Ltd. All rights reserved.
Robin, C. M.
2005-12-01
Many fluid mechanical experiments with direct applications to Earth Science are performed with sugary syrups using conceptually straightforward procedures. Corn syrup has indeed proven to be a godsend for those studying convection and related non-linear phenomena. In addition, however, it gives experimentalists a deep physical intuition for the interior workings of hot planets. The basic concepts behind plate tectonics and mantle convection are not difficult; indeed, although they may not be aware of it, most students probably have a basic intuitive understanding of fluid mechanics gained in their daily life. However, the large size and long time scale of geophysical processes may be quite intimidating to young students. Even a simple geophysical experiment requires a complicated array of coolers, heaters and measuring and recording equipment. It is of interest to introduce students to the geodynamical concepts that can be visualized in a high-tech lab using familiar processes and equipment. Using a homemade apparatus and grocery store supplies, I propose using a 'Stove-top Earth pecan pie' to introduce simple geodynamic concepts to middle- and high-school students. The initially cold syrup heats up and the pecans begin to float (continent formation), the syrup begins to convect (mantle convection), and convection slows down after the heat is removed (secular cooling). Even Wilson cycles can be simulated by moving the pan to one side or the other of the stovetop or heating element. The activity formally introduces students to convection and its application to the earth, and makes them think about plate motion, heat transfer, scaling, and experimental procedures. As an added bonus, they can eat their experiments after recess!
Fowler, C. M. R.
2005-02-01
The second edition of this acclaimed textbook has been brought fully up-to-date to reflect the latest advances in geophysical research. It is designed for students in introductory geophysics courses who have a general background in the physical sciences, including introductory calculus. New to this edition are a section of color plates and separate sections on the earth's mantle and core. The book also contains an extensive glossary of terms, and includes numerous exercises for which solutions are available to instructors from solutions@cambridge.org. First Edition Hb (1990): 0-521-37025-6 First Edition Pb (1990): 0-521-38590-3
Directory of Open Access Journals (Sweden)
Jose Miguel Correa
2014-06-01
Full Text Available The film Bones of the Earth (Riglin, Cunninham & Correa, 2014 is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective creation is built. A sense of community, on-going inquiry, connections and social commitment inform the creative process. As a result, the video’s nearly five intense minutes are a metaphor for the search for personal meaning, connection with nature and intersubjective positioning in a world that undergoes constant change.
Paquet, P.
1991-10-01
The European Space Agency's strategy concerning the solid Earth program is reviewed. Improvement of current knowledge of the global geopotential fields, both gravity and magnetic, was stressed as the highest priority. It was agreed that the objectives and goals of the planned Aristoteles mission correspond to this priority, and the need to realize this part of the program was stated. The interdisciplinary links of the program were identified, and it was decided that this program could make substantial contributions to research of oceans, climate and global change, atmosphere, ice and land surfaces.
Jasak, Hrvoje; Gatin, Inno; Vukčević, Vuko
2017-10-01
In Fluid Structure Interaction (FSI) problems encountered in marine hydrodynamics, the pressure field and the velocity of the rigid body are tightly coupled. This coupling is traditionally resolved in a partitioned manner by solving the rigid body motion equations once per nonlinear correction loop, updating the position of the body and solving the fluid flow equations in the new configuration. The partitioned approach requires a large number of nonlinear iteration loops per time-step. In order to enhance the coupling, a monolithic approach is proposed in Finite Volume (FV) framework, where the pressure equation and the rigid body motion equations are solved in a single linear system. The coupling is resolved by solving the rigid body motion equations once per linear solver iteration of the pressure equation, where updated pressure field is used to calculate new forces acting on the body, and by introducing the updated rigid body boundary velocity in to the pressure equation. In this paper the monolithic coupling is validated on a simple 2D heave decay case. Additionally, the method is compared to the traditional partitioned approach (i.e. "strongly coupled" approach) in terms of computational efficiency and accuracy. The comparison is performed on a seakeeping case in regular head waves, and it shows that the monolithic approach achieves similar accuracy with fewer nonlinear correctors per time-step. Hence, significant savings in computational time can be achieved while retaining the same level of accuracy.
An improved cutoff rigidity model based on a modification of the Tyganenko 1989 magnetospheric model
Smart, Don
The Tyganenko (Planet. Space Sci., 37, 5-20, 1989) magnetospheric model is convenient to use and requires less computer recourses for the computation of geomagnetic cutoff rigidity models than the more sophisticated magnetospheric models. Its use by Smart et al. (Adv. Space Res., 37, 1206-1217, 2006) resulted in a useful set of world grids of geomagnetic cutoff rigidity values indexed by Kp and UT. Recent evaluation of these cutoff rigidity values by Rodgers et al. (J. Geophys. Res., 111, A04222, 2006) shows that for Kp values larger than 5, the equatorward latitude displacements of the cutoff rigidity contours were overestimated. A comparison of the Dst and Kp indices for the data interval used to construct the Tyganenko 1989 magnetospheric model shows that Dst increments of -50 nT are a good approximation of the effective Kp increment beyond the Kp 5 value. We present an improved set of cutoff rigidity world grids indexed by Kp and UT that are a better fit to the Rodgers et al. (2006) data than the original values by Smart et al. (2006).
Vertical velocity distribution in open-channel flow with rigid vegetation.
Zhu, Changjun; Hao, Wenlong; Chang, Xiangping
2014-01-01
In order to experimentally investigate the effects of rigid vegetation on the characteristics of flow, the vegetations were modeled by rigid cylindrical rod. Flow field is measured under the conditions of submerged rigid rod in flume with single layer and double layer vegetations. Experiments were performed for various spacings of the rigid rods. The vegetation models were aligned with the approaching flow in a rectangular channel. Vertical distributions of time-averaged velocity at various streamwise distances were evaluated using an acoustic Doppler velocimeter (ADV). The results indicate that, in submerged conditions, it is difficult to described velocity distribution along the entire depth using unified function. The characteristic of vertical distribution of longitudinal velocity is the presence of inflection. Under the inflection, the line is convex and groove above inflection. The interaction of high and low momentum fluids causes the flow to fold and creates strong vortices within each mixing layer. Understanding the flow phenomena in the area surrounding the tall vegetation, especially in the downstream region, is very important when modeling or studying the riparian environment. ADV measures of rigid vegetation distribution of the flow velocity field can give people a new understanding.
Allioux-Guérin, Myriam; Icard-Arcizet, Delphine; Durieux, Christiane; Hénon, Sylvie; Gallet, François; Mevel, Jean-Claude; Masse, Marie-Jo; Tramier, Marc; Coppey-Moisan, Maïté
2009-01-01
Abstract We investigate the dynamic response of single cells to weak and local rigidities, applied at controlled adhesion sites. Using multiple latex beads functionalized with fibronectin, and each trapped in its own optical trap, we study the reaction in real time of single 3T3 fibroblast cells to asymmetrical tensions in the tens of pN · μm−1 range. We show that the cell feels a rigidity gradient even at this low range of tension, and over time develops an adapted change in the force exerted on each adhesion site. The rate at which force increases is proportional to trap stiffness. Actomyosin recruitment is regulated in space and time along the rigidity gradient, resulting in a linear relationship between the amount of recruited actin and the force developed independently in trap stiffness. This time-regulated actomyosin behavior sustains a constant and rigidity-independent velocity of beads inside the traps. Our results show that the strengthening of extracellular matrix-cytoskeleton linkages along a rigidity gradient is regulated by controlling adhesion area and actomyosin recruitment, to maintain a constant deformation of the extracellular matrix. PMID:18931254
Directory of Open Access Journals (Sweden)
J. H. Davies
2010-02-01
Full Text Available We present a revised estimate of Earth's surface heat flux that is based upon a heat flow data-set with 38 347 measurements, which is 55% more than used in previous estimates. Our methodology, like others, accounts for hydrothermal circulation in young oceanic crust by utilising a half-space cooling approximation. For the rest of Earth's surface, we estimate the average heat flow for different geologic domains as defined by global digital geology maps; and then produce the global estimate by multiplying it by the total global area of that geologic domain. The averaging is done on a polygon set which results from an intersection of a 1 degree equal area grid with the original geology polygons; this minimises the adverse influence of clustering. These operations and estimates are derived accurately using methodologies from Geographical Information Science. We consider the virtually un-sampled Antarctica separately and also make a small correction for hot-spots in young oceanic lithosphere. A range of analyses is presented. These, combined with statistical estimates of the error, provide a measure of robustness. Our final preferred estimate is 47±2 TW, which is greater than previous estimates.
Diatomaceous Earths - Natural Insecticides
Directory of Open Access Journals (Sweden)
Zlatko Korunić
2013-01-01
Full Text Available The regulatory issues for diatomaceous earth (DE cover three fields: consumer safety,worker safety, and proof of efficacy against pests. For consumer safety, regulatory issuesare similar to those for other additives, and a principal benefit of DEs is their removal bynormal processing methods. For worker safety, regulatory issues are similar to those forother dusts, such as lime. The proof of potential insecticide values of DE may be assessedby using the analysis of physical and chemical properties of DE and its effect on grainproperties and the proof of efficacy may be regulated by bioassay of standard design.Integrated pest management (IPM, a knowledge-based system, is rapidly providing aframework to reduce dependence on synthetic chemical pesticides. The main principleof post-harvest IPM is to prevent problems rather than to react to them. The specificcurative measures using synthetic pesticides should be applied only when infestationoccurs. DE and enhanced diatomaceous earth (EDE formulations hold significant promiseto increase the effectiveness and broaden the adoption of IPM strategies, thereby reducingthe need for synthetic pesticides. By incorporating DE in an effective IPM program,grain is protected against infestation, loss caused by insects is prevented and grain qualityis maintained until the grain is processed. Cases study data on the use of DE for commodityand structural treatment show that DE is already a practical alternative to syntheticpesticides in some applications.
A Governance Roadmap and Framework for EarthCube
Governance Steering Committee, EarthCube
2013-04-01
EarthCube is a process and an outcome, established to transform the conduct of research through the development of community-guided cyberinfrastructure for the Geosciences as the prototype for potential deployment across all domain sciences. EarthCube aims to create a knowledge management system and infrastructure that integrates all Earth system and human dimensions data in an open transparent, and inclusive manner. EarthCube requires broad community participation in concept, framework, and implementation and must not be hindered by rigid preconceptions. We discovered widely varying interpretations, expectations, and assumptions about governance among EarthCube participants. Our definition of governance refers to the processes, structure and organizational elements that determine, within an organization or system of organizations, how power is exercised, how stakeholders have their say, how decisions are made, and how decision makers are held accountable. We have learned, from historic infrastructure case studies, background research on governance and from community feedback during this roadmap process, that other types of large-scale, complex infrastructures, including the Internet, have no central control, administration, or management. No national infrastructure that we examined is governed by a single entity, let alone a single governance archetype. Thus we feel the roadmap process must accommodate a governance system or system of systems that may have a single governing entity, particularly at the start, but can evolve into a collective of governing bodies as warranted, in order to be successful. A fast-track process during Spring, 2012 culminated in a Governance Roadmap delivered to an NSF-sponsored charrette in June with an aggressive timetable to define and implement a governance structure to enable the elements of EarthCube to become operational expeditiously. Our goal is to help ensure the realization of this infrastructure sooner, more efficiently, and
Merlini, Anna; Grieco, Giovanni; Oneta, Cristina
2015-04-01
Geology needs to be explained and narrated to the people, focusing on the goal of making that big change of mindset that will allow individuals and the entire community to tune into the timing and the ways in which the Earth evolves. In order to achieve these important goals it is necessary to educate children from an early age so that they learn to live an environmentally friendly life. With the project "School, Earth and imagination" we introduce, with a fun and new way, notions and topics in geological and environmental sciences in schools at all levels with the final goal of improving both knowledge and sensibility for these topics into the community. Through this project we start from the children (kindergarten and primary school, ages between 3 and 8 years) because they are the foundation of our society, and without foundations nothing can be built. The "School, Earth and imagination" project wants to give the children a real opportunity to approach reality and in general the surrounding environment, for the first time even before the traditional scholastic experience, with a scientific point of view, experimenting some basic physical concepts like temperature, weight, hardness and so on directly through their body. The project is structured and developed in modules that provide a high flexibility in order to meet needs and requirements of different schools in different situations. Each module is part of the journey of Mariolino, a character that represents a very curious child who introduces basic concepts associating them to geological processes. The Journey of Mariolino, as each module, follows an insistent scheme that starts from the presentation of the problem, follows with its discussion through direct questions and ends with experimentation of the hypotheses that children have proposed to validate the solution of the problem. Each module is independent and never ends without giving children a solution and is always structured with a practical activity
Aspects concerning verification methods and rigidity increment of complex technological systems
Casian, M.
2016-11-01
Any technological process and technology aims a quality and precise product, something almost impossible without high rigidity machine tools, equipment and components. Therefore, from the design phase, it is very important to create structures and machines with high stiffness characteristics. At the same time, increasing the stiffness should not raise the material costs. Searching this midpoint between high rigidity and minimum expenses leads to investigations and checks in structural components through various methods and techniques and sometimes quite advanced methods. In order to highlight some aspects concerning the significance of the mechanical equipment rigidity, the finite element method and an analytical method based on the use Mathcad software were used, by taking into consideration a subassembly of a grinding machine. Graphical representations were elaborated, offering a more complete image about the stresses and deformations able to affect the considered mechanical subassembly.
Estimating the orientation of a rigid body moving in space using inertial sensors
Energy Technology Data Exchange (ETDEWEB)
He, Peng, E-mail: peng.he.1@ulaval.ca; Cardou, Philippe, E-mail: pcardou@gmc.ulaval.ca [Université Laval, Robotics Laboratory, Department of Mechanical Engineering (Canada); Desbiens, André, E-mail: andre.desbiens@gel.ulaval.ca [Université Laval, Department of Electrical and Computer Engineering (Canada); Gagnon, Eric, E-mail: Eric.Gagnon@drdc-rddc.gc.ca [RDDC Valcartier (Canada)
2015-09-15
This paper presents a novel method of estimating the orientation of a rigid body moving in space from inertial sensors, by discerning the gravitational and inertial components of the accelerations. In this method, both a rigid-body kinematics model and a stochastic model of the human-hand motion are formulated and combined in a nonlinear state-space system. The state equation represents the rigid body kinematics and stochastic model, and the output equation represents the inertial sensor measurements. It is necessary to mention that, since the output equation is a nonlinear function of the state, the extended Kalman filter (EKF) is applied. The absolute value of the error from the proposed method is shown to be less than 5 deg in simulation and in experiments. It is apparently stable, unlike the time-integration of gyroscope measurements, which is subjected to drift, and remains accurate under large accelerations, unlike the tilt-sensor method.
Compliant mechanism road bicycle brake: a rigid-body replacement case study
Energy Technology Data Exchange (ETDEWEB)
Olsen, Brian M [Los Alamos National Laboratory; Howell, Larry L [NON LANL; Magleby, Spencer P [NON LANL
2011-01-19
The design of high-performance bicycle brakes is complicated by the competing design objectives of increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace current rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.
Adaptive rheology and ordering of cell cytoskeleton govern matrix rigidity sensing.
Gupta, Mukund; Sarangi, Bibhu Ranjan; Deschamps, Joran; Nematbakhsh, Yasaman; Callan-Jones, Andrew; Margadant, Felix; Mège, René-Marc; Lim, Chwee Teck; Voituriez, Raphaël; Ladoux, Benoît
2015-06-25
Matrix rigidity sensing regulates a large variety of cellular processes and has important implications for tissue development and disease. However, how cells probe matrix rigidity, and hence respond to it, remains unclear. Here, we show that rigidity sensing and adaptation emerge naturally from actin cytoskeleton remodelling. Our in vitro experiments and theoretical modelling demonstrate a biphasic rheology of the actin cytoskeleton, which transitions from fluid on soft substrates to solid on stiffer ones. Furthermore, we find that increasing substrate stiffness correlates with the emergence of an orientational order in actin stress fibres, which exhibit an isotropic to nematic transition that we characterize quantitatively in the framework of active matter theory. These findings imply mechanisms mediated by a large-scale reinforcement of actin structures under stress, which could be the mechanical drivers of substrate stiffness-dependent cell shape changes and cell polarity.
Technical characteristics of rigid sprayed PUR and PIR foams used in construction industry
Gravit, Marina; Kuleshin, Aleksey; Khametgalieva, Elina; Karakozova, Irina
2017-10-01
The article describes the distinctive properties of rigid polyurethane foam and polyisocyanurate (PUR and PIR). A brief review of the research was carried out on their modification with an objective to improve the thermal insulation properties and reducing the combustibility. A comparative analysis of the technical characteristics of rigid PUR and PIR foams of various manufacturers is presented. The problems of the state of the market for the production of polyurethane foam and polyisocyanurate in Russia have been marked. It is established that the further development of the fabrication technology of heat-insulating sprayed rigid PUR and PIR foams requires uniformity of technical characteristics of original components and finished products. Moreover, it requires the creation of unified information base for raw materials and auxiliary materials used in the production of PUR and PIR foam.
Mouse whole-body organ mapping by non-rigid registration approach
Xiao, Di; Zahra, David; Bourgeat, Pierrick; Berghofer, Paula; Acosta Tamayo, Oscar; Green, Heather; Gregoire, Marie Claude; Salvado, Olivier
2011-03-01
Automatic small animal whole-body organ registration is challenging because of subject's joint structure, posture and position difference and loss of reference features. In this paper, an improved 3D shape context based non-rigid registration method is applied for mouse whole-body skeleton registration and lung registration. A geodesic path based non-rigid registration method is proposed for mouse torso skin registration. Based on the above registration methods, a novel non-rigid registration framework is proposed for mouse whole-body organ mapping from an atlas to new scanned CT data. A preliminary experiment was performed to test the method on lung and skin registration. A whole-body organ mapping was performed on three target data and the selected organs were compared with the manual outlining results. The robust of the method has been demonstrated.
Rigid spine reinforced polymer microelectrode array probe and method of fabrication
Tabada, Phillipe; Pannu, Satinderpall S
2014-05-27
A rigid spine-reinforced microelectrode array probe and fabrication method. The probe includes a flexible elongated probe body with conductive lines enclosed within a polymeric material. The conductive lines connect microelectrodes found near an insertion end of the probe to respective leads at a connector end of the probe. The probe also includes a rigid spine, such as made from titanium, fixedly attached to the probe body to structurally reinforce the probe body and enable the typically flexible probe body to penetrate and be inserted into tissue, such as neural tissue. By attaching or otherwise fabricating the rigid spine to connect to only an insertion section of the probe body, an integrally connected cable section of the probe body may remain flexible.
Nennig, Benoit; Renou, Ygaäl; Groby, Jean-Philippe; Aurégan, Yves
2012-05-01
This work investigates the acoustical properties of a multilayer porous material in which periodic inclusions are embedded. The material is assumed to be backed by a rigid wall. Most of the studies performed in this field used the multipole method and are limited to circular shape inclusions. Here, a mode matching approach, more convenient for a layered system, is adopted. The inclusions can be in the form of rigid scatterers of an arbitrary shape, in the form of an air-filled cavity or in the form of a porous medium with contrasting properties. The computational approach is validated on simple geometries against other numerical schemes and with experimental results obtained in an anechoic room on a rigid grating embedded in a porous material made of 2 mm glass beads. The method is used to study the acoustic absorption behavior of this class of materials in the low frequency range and at a range of angles of incidence.
Modelling of Rigid Walled Enclosure Couple to a Flexible Wall using Matlab and Ansys APDL
Zaman, I.; Rozlan, S. A. M.; Azmir, N. A.; Ismon, M.; Madlan, M. A.; Yahya, M. N.; Zainulabidin, M. H.; Sani, M. S. M.; Noh, M. F. M.
2017-10-01
Generally, solutions to improve the noise problems in enclosure are to redesign or modifying the system such as increasing the thickness of the wall panels, enhancing the elasticity of the structure, and increase the damping mechanism of the wall structure. In this paper, the application of vibroacoustic modelling of enclosure coupled to a flexible wall was presented. The sound pressure characteristics of rigid walled enclosure, such as natural frequency and mode shape were determined using two approaches which are finite element simulation of Ansys® and mathematical model. The mathematical equations derived in Matlab® such as rigid walled enclosure and rigid walled enclosure coupled to flexible wall were used to validate finite element analysis (FEA). The result indicates that the theory and FEA display in a good agreement. Thus, proved that the FE model was accurate and can be applied in further research such as sound pressure and noise attenuation in enclosure.
Cosmic Rays in Magnetospheres of the Earth and other Planets
Dorman, Lev
2009-01-01
This monograph describes the behaviour of cosmic rays in the magnetosphere of the Earth and of some other planets. Recently this has become an important topic both theoretically, because it is closely connected with the physics of the Earth’s magnetosphere, and practically, since cosmic rays determine a significant part of space weather effects on satellites and aircraft. The book contains eight chapters, dealing with – The history of the discovery of geomagnetic effects caused by cosmic rays and their importance for the determination of the nature of cosmic rays or gamma rays – The first explanations of geomagnetic effects within the framework of the dipole approximation of the Earth’s magnetic field – Trajectory computations of cutoff rigidities, transmittance functions, asymptotic directions, and acceptance cones in the real geomagnetic field taking into account higher harmonics – Cosmic ray latitude-longitude surveys on ships, trains, tracks, planes, balloons and satellites for determining the...
Directory of Open Access Journals (Sweden)
Abdulla Al Ansari
2013-09-01
Full Text Available Introduction: Penile prosthesis implantation is one of the treatment choices that is kept for patients who were not satisfied with other treatments. Although penile prosthesis satisfaction rates are higher, there are some dissatisfied patients. The patients’ reasons are mostly shortness and softness of implanted prosthesis. It was previously demonstrated that penile axial rigidity of more than 500 grams is enough for successful vaginal intromission. To our knowledge, there is no study comparing axial rigidity of penile prosthesis and satisfaction. Objectives: The aim of this study was to examine whether axial rigidity of penile prosthesis had impact on patient and partner satisfaction. Materials and Methods: We enrolled one hundred patients who were implanted penile prosthesis before to evaluate their penile axial rigidity. We used Rigidometry (by using the digital inflection rigidometer to assess the minimal axial pressure to bend the implanted penis. Results: We demonstrated that mean axial pressure to bend the implanted penis was 984.8 ± 268.7 grams. Overall satisfaction score with the penile prosthesis implant was 4.55 and 4.49 (out of 5 in patients and partners, respectively. In total, seven men were unsatisfied with their implant and reported a mean satisfaction score of 0.6 ± 0.48 (out of 5. All prostheses types showed good and more than 500 grams axial rigidity. The patients with Ambicor type, which were buckled at about 710.5 grams, showed worse satisfaction rates in comparison to other prostheses in two patients. Digital inflection rigidometer results of other penile prosthesis types in unsatisfied patient were 842.0, 872.0, 887.0 and 920 g. in CX700, Titan, Genesis and Titan OTR, respectively. Conclusion: We demonstrated that dissatisfaction rate was highest in Ambicor prosthesis implanted patients. Additionally, patients with 3-piece penile prosthesis were more satisfied than 2-piece or malleable ones, interestingly, although
Effect of Cyclooxygenase-2 inhibition on rigidity of animal model of Parkinson's disease
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Fathi Moghaddam
2008-08-01
Full Text Available "nBackground: Parkinson's disease (PD is a degenerative neurodopaminergic disease in nigrostriatum pathway of animals and human, the resultant loss of nerve terminals accompanied by dopamine-glutamate and other related neurotransmitters-imbalances in this pathway are responsible for most of the movement abnormalities. Increasing evidence suggests that an inflammatory reaction accompanies the pathological processes caused by Cyclooxygenase-2 (COX-2 seen in many neurodegenerative disorders, including PD. These findings have not indicated any evidence based on the effect of selective and non selective COX-2 inhibitors on the rigidity of PD."n"nMethods: The rats left substantia nigra pars compacta (SNc was destroyed using the electrical lesion thus PD model was created. Then oral aspirin and celecoxib (200, 400 mg/kg were administrated to parkinsonian rats acutely and then the rigidity was evaluated using Murprogo's Method."n"nResults: Both compounds were able to decrease the rigidity of parkinsonian rats (p<0.05 respectively but selective cox-2 inhibitor (celecoxib was found more effective and potent than that of non selective cox-2 inhibitor (aspirin."n"nConclusion: The findings suggest that COX-2 inhibition decreases the rigidity of PD in the animal model. Therefore, as results of the study COX-2 inhibition was shown good evidence based on the use of aspirin and celecoxib and PD affiliated rigidity improvement that this can be beneficial and interest for neuroscientists. These findings are additional pharmacological and medicinal information to further assess of non steroidal anti inflammatory drugs (NSAIDs as alternative therapeutic agents for PD affiliated rigidity treatment. Further experiments seem to be necessary to complete this research such as investigation the effects of NSAIDs on the striatum neurotransmission pathway
Rigid Residue Scan Simulations Systematically Reveal Residue Entropic Roles in Protein Allostery.
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Robert Kalescky
2016-04-01
Full Text Available Intra-protein information is transmitted over distances via allosteric processes. This ubiquitous protein process allows for protein function changes due to ligand binding events. Understanding protein allostery is essential to understanding protein functions. In this study, allostery in the second PDZ domain (PDZ2 in the human PTP1E protein is examined as model system to advance a recently developed rigid residue scan method combining with configurational entropy calculation and principal component analysis. The contributions from individual residues to whole-protein dynamics and allostery were systematically assessed via rigid body simulations of both unbound and ligand-bound states of the protein. The entropic contributions of individual residues to whole-protein dynamics were evaluated based on covariance-based correlation analysis of all simulations. The changes of overall protein entropy when individual residues being held rigid support that the rigidity/flexibility equilibrium in protein structure is governed by the La Châtelier's principle of chemical equilibrium. Key residues of PDZ2 allostery were identified with good agreement with NMR studies of the same protein bound to the same peptide. On the other hand, the change of entropic contribution from each residue upon perturbation revealed intrinsic differences among all the residues. The quasi-harmonic and principal component analyses of simulations without rigid residue perturbation showed a coherent allosteric mode from unbound and bound states, respectively. The projection of simulations with rigid residue perturbation onto coherent allosteric modes demonstrated the intrinsic shifting of ensemble distributions supporting the population-shift theory of protein allostery. Overall, the study presented here provides a robust and systematic approach to estimate the contribution of individual residue internal motion to overall protein dynamics and allostery.
Virtual rigid body: a new optical tracking paradigm in image-guided interventions
Cheng, Alexis; Lee, David S.; Deshmukh, Nishikant; Boctor, Emad M.
2015-03-01
Tracking technology is often necessary for image-guided surgical interventions. Optical tracking is one the options, but it suffers from line of sight and workspace limitations. Optical tracking is accomplished by attaching a rigid body marker, having a pattern for pose detection, onto a tool or device. A larger rigid body results in more accurate tracking, but at the same time large size limits its usage in a crowded surgical workspace. This work presents a prototype of a novel optical tracking method using a virtual rigid body (VRB). We define the VRB as a 3D rigid body marker in the form of pattern on a surface generated from a light source. Its pose can be recovered by observing the projected pattern with a stereo-camera system. The rigid body's size is no longer physically limited as we can manufacture small size light sources. Conventional optical tracking also requires line of sight to the rigid body. VRB overcomes these limitations by detecting a pattern projected onto the surface. We can project the pattern onto a region of interest, allowing the pattern to always be in the view of the optical tracker. This helps to decrease the occurrence of occlusions. This manuscript describes the method and results compared with conventional optical tracking in an experiment setup using known motions. The experiments are done using an optical tracker and a linear-stage, resulting in targeting errors of 0.38mm+/-0.28mm with our method compared to 0.23mm+/-0.22mm with conventional optical markers. Another experiment that replaced the linear stage with a robot arm resulted in rotational errors of 0.50+/-0.31° and 2.68+/-2.20° and the translation errors of 0.18+/-0.10 mm and 0.03+/-0.02 mm respectively.
Dimensional Metrology of Non-rigid Parts Without Specialized Inspection Fixtures =
Sabri, Vahid
Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures and technological advances. Functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We will focus here on the geometric inspection of non-rigid (flexible) parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a free-state condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the installation and inspection processes are expensive and time-consuming. Our aim in this thesis is therefore to develop an inspection method which eliminates the need for specialized fixtures. This is done by acquiring a point cloud from the part in a free-state condition using a contactless measuring device such as optical scanning and comparing it with the CAD model for the deviation identification. Using a non-rigid registration method and finite element analysis, we numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of displacement boundary conditions for simulating unfixed parts. In addition, we propose a numerical method for dimensional metrology of non-rigid parts in a free-state condition based on the arc length measurement by calculating the geodesic distance using the Fast Marching Method (FMM). In this thesis, we apply our developed methods on industrial non-rigid parts with free-form surfaces simulated with different types of
Steiner, Mark E; Smart, L Ryan
2012-06-01
This study evaluated the ability of flexible instruments compared with rigid instruments to place anatomic femoral tunnels in anterior cruciate ligament reconstructions by use of both transtibial drilling and anteromedial drilling without hyperflexion. Rigid and flexible pins were placed in 12 matched pairs of cadaveric knees with transtibial drilling (6 pairs) and anteromedial drilling (6 pairs) at 110° of flexion. Intraosseous pin lengths, femoral exit locations, and tunnel alignment were measured. Transtibial drilling with rigid pins placed relatively vertical femoral tunnels 5.8 ± 1.0 mm superior to the central anterior cruciate ligament insertion. Transtibial drilling with flexible pins placed tunnels in the center of the femoral attachment, but the tunnels were relatively close to the posterior femoral cortex, with a mean distance of 8.0 ± 5.9 mm (P Tunnel lengths with flexible pins were longer (42.0 ± 7.2 mm) compared with tunnel lengths with rigid pins (32.5 ± 7.1 mm) (P tunnels. Transtibial drilling with flexible pins produced anatomic tunnels, but the tunnels were close to the posterior femoral cortex. Anteromedial drilling without hyperflexion produced anatomic tunnels by use of rigid and flexible instruments, but with flexible instruments, the tunnels were longer and were farther from the posterior femoral cortex. Anteromedial drilling with flexible pins produced tunnels with good length and the best position. Flexible instruments compared with rigid instruments can facilitate the creation of anatomic femoral tunnels by use of anteromedial drilling without hyperflexion. Copyright © 2012 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics.
Tao, Peng; Sodt, Alexander J; Shao, Yihan; König, Gerhard; Brooks, Bernard R
2014-10-14
The calculations of potential of mean force along complex chemical reactions or rare events pathways are of great interest because of their importance for many areas in chemistry, molecular biology, and material science. The major difficulty for free energy calculations comes from the great computational cost for adequate sampling of the system in high-energy regions, especially close to the reaction transition state. Here, we present a method, called FEG-RBD, in which the free energy gradients were obtained from rigid body dynamics simulations. Then the free energy gradients were integrated along a reference reaction pathway to calculate free energy profiles. In a given system, the reaction coordinates defining a subset of atoms (e.g., a solute, or the quantum mechanics (QM) region of a quantum mechanics/molecular mechanics simulation) are selected to form a rigid body during the simulation. The first-order derivatives (gradients) of the free energy with respect to the reaction coordinates are obtained through the integration of constraint forces within the rigid body. Each structure along the reference reaction path is separately subjected to such a rigid body simulation. The individual free energy gradients are integrated along the reference pathway to obtain the free energy profile. Test cases provided demonstrate both the strengths and weaknesses of the FEG-RBD method. The most significant benefit of this method comes from the fast convergence rate of the free energy gradient using rigid-body constraints instead of restraints. A correction to the free energy due to approximate relaxation of the rigid-body constraint is estimated and discussed. A comparison with umbrella sampling using a simple test case revealed the improved sampling efficiency of FEG-RBD by a factor of 4 on average. The enhanced efficiency makes this method effective for calculating the free energy of complex chemical reactions when the reaction coordinate can be unambiguously defined by a
Al Ansari, Abdulla; Talib, Raidh A; Canguven, Onder; Shamsodini, Ahmad
2013-09-26
Penile prosthesis implantation is one of the treatment choices that is kept for patients who were not satisfied with other treatments. Although penile prosthesis satisfaction rates are higher, there are some dissatisfied patients. The patients’ reasons are mostly shortness and softness of implanted prosthesis. It was previously demonstrated that penile axial rigidity of more than 500 grams is enough for successful vaginal intromission. To our knowledge, there is no study comparing axial rigidity of penile prosthesis and satisfaction. The aim of this study was to examine whether axial rigidity of penile prosthesis had impact on patient and partner satisfaction. We enrolled one hundred patients who were implanted penile prosthesis before to evaluate their penile axial rigidity. We used Rigidometry (by using the digital inflection rigidometer) to assess the minimal axial pressure to bend the implanted penis. We demonstrated that mean axial pressure to bend the implanted penis was 984.8 ± 268.7 grams. Overall satisfaction score with the penile prosthesis implant was 4.55 and 4.49 (out of 5) in patients and partners, respectively. In total, seven men were unsatisfied with their implant and reported a mean satisfaction score of 0.6 ± 0.48 (out of 5). All prostheses types showed good and more than 500 grams axial rigidity. The patients with Ambicor type, which were buckled at about 710.5 grams, showed worse satisfaction rates in comparison to other prostheses in two patients. Digital inflection rigidometer results of other penile prosthesis types in unsatisfied patient were 842.0, 872.0, 887.0 and 920 g. in CX700, Titan, Genesis and Titan OTR, respectively. We demonstrated that dissatisfaction rate was highest in Ambicor prosthesis implanted patients. Additionally, patients with 3-piece penile prosthesis were more satisfied than 2-piece or malleable ones, interestingly, although some cases had lower axial rigidity results.
Reichl, Michael; Kueny, Rebecca A; Danyali, Reza; Obid, Peter; Übeyli, Hüseyin; Püschel, Klaus; Morlock, Michael M; Huber, Gerd; Niemeyer, Thomas; Richter, Alexander
2017-05-01
Biomechanical ex vivo study. To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η=0.82) and in Th12-L1 (Pinstrumentation in all segments. Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.
The Incidence and Evolution of Parkinsonian Rigidity in Rett Syndrome: A Pilot Study.
Humphreys, Peter; Barrowman, Nick
2016-07-01
Patients with Rett syndrome (RTT) may demonstrate parkinsonian features. Here, we report a preliminary cross-sectional and prospective evaluation of the evolution, regional distribution, and eventual incidence of rigid tone in a cohort of MECP2 mutation-positive patients. In 51 participants, muscle tone rigidity in extremity regions and neck plus hypomimia were quantified using an RTT rigidity distribution (RTTRD) score with a range of 0 to 15. RTTRD scores were correlated with age, ability to walk and speak, mutation type, and, in a small subgroup (n=9), cerebrospinal fluid (CSF) homovanillic acid (HVA) and 5-hydroxyindole-acetic acid levels. Participant ages ranged from 2 years and 5 months, to 54 years. Rigidity was found in 43/51 (84.3%); it appeared as early as age 3, increased in extent with age, and was present in all participants aged ≥13. Ankle region rigidity appeared first, followed by proximal legs, arms, neck, and face. Ambulatory participants (n=21) had lower RTTRD scores than nonambulatory (n=30; p=0.003). We found a trend to lower scores in participants with retained speech (n=13) versus those with none (n=38; p=0.074), and no difference in scores for those with truncating (n=25) versus missense mutations (n=22; p=0.387). RTTRD scores correlated negatively with CSF HVA levels (R=-0.83; p=0.005), but not with 5-hydroxyindole-acetic acid levels (R=-0.45; p=0.22). Although assessment of muscle tone is somewhat subjective and the RTTRD has not been validated, this study nevertheless suggests that parkinsonian rigidity in RTT is common and frequently increases in extent with age; its severity correlates directly with impaired ambulation and inversely with CSF HVA levels.
Levy, R.
1991-01-01
Post-processing algorithms are given to compute the vibratory elastic-rigid coupling matrices and the modal contributions to the rigid-body mass matrices and to the effective modal inertias and masses. Recomputation of the elastic-rigid coupling matrices for a change in origin is also described. A computational example is included. The algorithms can all be executed by using standard finite-element program eigenvalue analysis output with no changes to existing code or source programs.
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Talat Körpınar
2012-01-01
Full Text Available In this paper, we study spacelike biharmonic slant helices according to Bishop frame in the Lorentzian group of rigid motions E(1,1. We characterize the spacelike biharmonic slant helices in terms of their curvatures in the Lorentzian group of rigid motions E(1,1. Finally, we obtain parametric equations of spacelike biharmonic slant helices according to Bishop frame in the Lorentzian group of rigid motions E(1,1.
Identification of the 3D Vibratory Motion of a Rigid Body by Accelerometer Measurements
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Francesca Di Puccio
2004-01-01
Full Text Available The identification of the motion of a rigid body by means of linear accelerometers is a problem already investigated by many researchers, but still debated. The optimisation of the number and placement of accelerometers is also another important aspect of the problem. In this study, an experimental procedure is proposed and applied to identify the rigid-body vibratory motion of the steering wheel of a sporting car, by means of six linear accelerometers. Some numerical simulations for investigating possible errors are also presented.
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Yakhlef O.
2017-06-01
Full Text Available A fixed point algorithmis proposed to solve a fluid-structure interaction problem with the supplementary constraint that the structure displacements are limited by a rigid obstacle. Fictitious domain approach with penalization is used for the fluid equations. The surface forces from the fluid acting on the structure are computed using the fluid solution in the structure domain. The continuity of the fluid and structure velocities is imposed through the penalization parameter. The constraint of non-penetration of the elastic structure into the rigid obstacle is treated weakly. A convex constrained optimization problem is solved in order to get the structure displacements. Numerical results are presented.
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Zheyu Xu
2017-05-01
Full Text Available We present a case of 32-year-old male with profound mental retardation and autism spectrum disorder who had presented with seizures, rigidity and elevated creatine kinase and was initially diagnosed as neuroleptic malignant syndrome (NMS. The patient subsequently had a complicated clinical course, developing refractory status epilepticus, which lead to the eventual diagnosis of progressive encephalomyelitis with rigidity and myoclonus (PERM. We discuss the clinical similarities and differences between NMS and PERM, and highlight the need to consider alternative diagnoses when the clinical picture of NMS is atypical, particularly in this patient group where the history and clinical examination may be challenging.
A non-rigid map fusion-based direct SLAM method for endoscopic capsule robots.
Turan, Mehmet; Almalioglu, Yasin; Araujo, Helder; Konukoglu, Ender; Sitti, Metin
2017-01-01
Since the development of capsule endoscopy technology, medical device companies and research groups have made significant progress to turn passive capsule endoscopes into robotic active capsule endoscopes. However, the use of robotic capsules in endoscopy still has some challenges. One such challenge is the precise localization of the actively controlled robot in real-time. In this paper, we propose a non-rigid map fusion based direct simultaneous localization and mapping method for endoscopic capsule robots. The proposed method achieves high accuracy for extensive evaluations of pose estimation and map reconstruction performed on a non-rigid, realistic surgical EsophagoGastroDuodenoscopy Simulator and outperforms state-of-the art methods.
Semi-rigid brace and taping decrease variability of the ankle joint position sense
Barbanera,Márcia; Mazuchi,Flávia de Andrade e Souza; Batista,José Paulo Berretta; Ultremare,Janaina de Moura; Iwashita,Juliana da Silva; Ervilha,Ulysses Fernandes
2014-01-01
The present study investigated the effect of taping and the semi-rigid ankle brace on ankle joint position sense. Sixteen healthy women (20.8 ± 2.3 years old) actively placed the ankle in a target position. The experimental conditions were: 1) wearing no orthosis device, 2) using semi-rigid brace, and 3) wearing ankle taping. Absolute error (AE) and variable error (VE) were calculated to obtain the joint position sense. We found an interaction effect between condition and target angle at 15o ...
Determination of Rigidity of Protein Bound Au(144) Clusters by Electron Cryomicroscopy.
Sexton, Jonathan Z; Ackerson, Christopher J
2010-09-30
A method for estimating the positional displacement of protein bound gold nanoparticles is presented and used to estimate the rigidity of linkage of Au(144) nanoparticles bound to a tetrameric model protein. We observe a distribution of displacement values where most Au(144) clusters are immobilized to within 3Å relative to the protein center of mass. The shape of the distribution suggests two physical processes of thermal motion and protein deformation. The application of this and similar rigid gold nanoparticle/protein conjugates in high resolution single particle electron cryo-microscopy is discussed.
Rigid registration of CT, MR and cryosection images using a GLCM framework
DEFF Research Database (Denmark)
Bro-Nielsen, Morten; Grimson, E.; Mosges, R.
1997-01-01
The majority of the available rigid registration measures are based on a 2-dimensional histogram of corresponding grey-values in the registered images. This paper shows that these features are similar to a family of texture measures based on grey level co-occurrence matrices (GLCM). Features from...... the GLCM literature are compared to the current range of measures using images from the visible human data set. The voxel-based rigid registration of cryosection and CT images have not been reported before. The tests show that mutual information is the best general measure, but some GLCM features...
Evolution of motions of a rigid body about its center of mass
Chernousko, Felix L; Leshchenko, Dmytro D
2017-01-01
The book presents a unified and well-developed approach to the dynamics of angular motions of rigid bodies subjected to perturbation torques of different physical nature. It contains both the basic foundations of the rigid body dynamics and of the asymptotic method of averaging. The rigorous approach based on the averaging procedure is applicable to bodies with arbitrary ellopsoids of inertia. Action of various perturbation torques, both external (gravitational, aerodynamical, solar pressure) and internal (due to viscous fluid in tanks, elastic and visco-elastic properties of a body) is considered in detail. The book can be used by researchers, engineers and students working in attitude dynamics of spacecraft.
Lee, Youmin; Kim, Yu Lim; Kim, Myung Hwa; Lee, Minyung
2013-11-01
Thioflavin T (ThT) exhibits an enormous increase in fluorescence intensity (or lifetime) upon binding to β-sheet rich protein aggregates. In this letter, we measured the fluorescence lifetimes of ThT in poly (ethylene oxide) (PEO) and poly (acrylic acid) (PAA) polymer films and nanofibers and observed that the excited-state motion of ThT is slowed down as the mechanical rigidity of medium increases. Using ThT as a rigidity sensor, we first demonstrate that the fluorescence lifetime imaging microscopy (FLIM) can easily distinguish the PEO and PAA nanofiber structures, which were not discernable by electron microscopy.
Kourtides, D. A.; Chiu, S. A.; Iverson, D. J.; Lowe, D. M.
1992-01-01
Described here is the thermal performance of rigid and flexible thermal protection systems considered for potential use in future Aeroassist Space Transfer Vehicles. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is described. Properties that were measured included the thermal conductivity of both rigid and flexible insulations at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The results from computerized thermal analysis models describing the thermal response of these materials subjected to flight conditions are included.
Correlation between floppy to rigid transitions and non-Arrhenius conductivity in glasses.
Malki, M; Micoulaut, M; Chaimbault, F; Vaills, Y
2006-04-14
Non-Arrhenius behavior is observed for a number of virgin potassium silicate glasses (1-x)SiO2-xK2O with a potassium oxide concentration larger than a certain value x = x(c). Recovering of Arrhenius behavior is provided by the annealing that enhances densification. These various results are the manifestation of the floppy or rigid nature of the network. Compositional effects and saturation with temperature can be analyzed with a combination of constraint theory and a point defect model. They underscore the key role played by network rigidity for the understanding of conduction and saturation effects in glassy electrolytes.
Deformable image registration with local rigidity constraints for cone-beam CT-guided spine surgery
Reaungamornrat, S.; Wang, A. S.; Uneri, A.; Otake, Y.; Khanna, A. J.; Siewerdsen, J. H.
2014-07-01
Image-guided spine surgery (IGSS) is associated with reduced co-morbidity and improved surgical outcome. However, precise localization of target anatomy and adjacent nerves and vessels relative to planning information (e.g., device trajectories) can be challenged by anatomical deformation. Rigid registration alone fails to account for deformation associated with changes in spine curvature, and conventional deformable registration fails to account for rigidity of the vertebrae, causing unrealistic distortions in the registered image that can confound high-precision surgery. We developed and evaluated a deformable registration method capable of preserving rigidity of bones while resolving the deformation of surrounding soft tissue. The method aligns preoperative CT to intraoperative cone-beam CT (CBCT) using free-form deformation (FFD) with constraints on rigid body motion imposed according to a simple intensity threshold of bone intensities. The constraints enforced three properties of a rigid transformation—namely, constraints on affinity (AC), orthogonality (OC), and properness (PC). The method also incorporated an injectivity constraint (IC) to preserve topology. Physical experiments involving phantoms, an ovine spine, and a human cadaver as well as digital simulations were performed to evaluate the sensitivity to registration parameters, preservation of rigid body morphology, and overall registration accuracy of constrained FFD in comparison to conventional unconstrained FFD (uFFD) and Demons registration. FFD with orthogonality and injectivity constraints (denoted FFD+OC+IC) demonstrated improved performance compared to uFFD and Demons. Affinity and properness constraints offered little or no additional improvement. The FFD+OC+IC method preserved rigid body morphology at near-ideal values of zero dilatation ({ D} = 0.05, compared to 0.39 and 0.56 for uFFD and Demons, respectively) and shear ({ S} = 0.08, compared to 0.36 and 0.44 for uFFD and Demons
Shen, H P; Zhou, J G; Shen, Y; Huang, L J
2001-12-01
To investigate the clinical effect of zygomatic complex (ZC) fracture via infraorbital incision and rigid fixation. To clinically classify 65 cases with ZC fractures,which treated with open reduction and minor titanium-plate internal fixation. (1) The operated area can be widely exposed via infraorbital incision. (2) ZC fractures can be reducted timely and correctly. (3) The fragments can be fixed rigidly with minor Ti-plaets. No injury to the facial nerve.The satisfactory rate of recovery was 95.4% (63/65). Operation through infraorbital incision is suitable to ZC fractures.
Bhatti, Abdul Qadir
2017-12-01
To demonstrate the characteristics of the nonlinear response of steel frames, an elastic dynamic response analysis of the semi-rigid frame is performed under the harmonic wave. The semi-rigid contact is represented by the alternating spring which is given stiffness by a three-parameter energy model which approaches the hysterical curve by hardening model. The properties of spectra and hysteric curves are presented. This study shows that (1) the greater the acceleration input capacitance the smaller the instant connection capability and the smaller is the response. (2) However, by allowing an extreme increase in capacitance input acceleration, response spectra can be increased as the contact stiffness results near zero.
Debonded arc-shaped interface conducting rigid line inclusions in piezoelectric composites
Wang, Xu; Schiavone, Peter
2017-10-01
We consider an arc-shaped conducting rigid line inclusion located at the interface between a circular piezoelectric inhomogeneity and an unbounded piezoelectric matrix subjected to remote uniform anti-plane shear stresses and in-plane electric fields. Moreover, one side of the rigid line inclusion has become fully debonded from the matrix or the inhomogeneity leading to the formation of an insulating crack. After the introduction of two sectionally holomorphic vector functions, the problem is reduced to a vector Riemann-Hilbert problem, which can be decoupled sequentially by repeated application of the orthogonality relations between the eigenvectors for two corresponding generalized eigenvalue problems.
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Karan Madan
2014-01-01
Full Text Available Background and Aim: Rigid bronchoscopy is often an indispensable procedure in the therapeutic management of a wide variety of tracheobronchial disorders. However, it is performed at only a few centers in adult patients in India. Herein, we report our initial 1-year experience with this procedure. Materials and Methods: A prospective observational study on the indications, outcomes, and safety of various rigid bronchoscopy procedures performed between November 2009 and October 2010. Improvement in dyspnea, cough, and the overall quality of life was recorded on a visual analog scale from 0 to 100 mm. A systematic review of PubMed was performed to identify studies reporting the use of rigid bronchoscopy from India. Results: Thirty-eight rigid bronchoscopies (50 procedures were performed in 19 patients during the study period. The commonest indication was benign tracheal stenosis followed by central airway tumor, and the procedures performed were rigid bronchoplasty, tumor debulking, and stent placement. The median procedure duration was 45 (range, 30-65 min. There was significant improvement in quality of life associated with therapeutic rigid bronchoscopy. Minor procedural complications were encountered in 18 bronchoscopies, and there was no procedural mortality. The systematic review identified 15 studies, all on the role of rigid bronchoscopy in foreign body removal. Conclusions: Rigid bronchoscopy is a safe and effective modality for treatment of a variety of tracheobronchial disorders. There is a dire need of rigid bronchoscopy training at teaching hospitals in India.
Escapa, A.; Getino, J.; Ferrándiz, J. M.
By means of the Hamiltonian theory of the rotation of the non-rigid Earth, we have obtained explicit expressions of the torques exerted by the fluid on the solid layers of two and three-layer Earth models as functions of the canonical Andoyer variables. When rewriting these formulae in terms of the components of angular velocities and symmetry axes of the layers, the transformated expressions are the same as those derived by other authors using different methods. Anyway, here the derivation is obtained in a much more simple way without the concurrence of hydrodynamics equations.
2011-01-01
In collaboration with the CineGlobe Film Festival, the One Day on Earth global film project invites you to share your story of scientific inspiration, scientific endeavors and technological advancement on 11 November 2011 (11.11.11). Technology in the 21st century continuously inspires us to re-imagine the world. From outer-space to cyberspace, new ideas that we hope will improve the lives of future generations keep us in a state of change. However, these new technologies may alter the nature of our shared existence in ways not yet known. On 11.11.11, we invite you to record the exciting ways that science is a part of your life, together with people around the world who will be documenting their lives on this day of global creation. See www.onedayonearth.org for details on how to participate.
Morris, Adrian J.; Kay, Stan
The Telephony Earth Station (TES), a digital full-mesh SCPC (single channel per carrier) system designed for satellite voice and data transmission is described. As compared to companded FM, the advanced speech compression and forward error correction techniques used by TES better achieve the quality, power, and bandwidth ideal for each application. In addition, the TES offers a fully demand-assigned voice call setup, handles point-to-point data channels, supports a variety of signaling schemes, and does not require any separate pilot receivers at the station, while keeping costs low through innovative technology and packaging. The TES can be used for both C-band and Ku-band (domestic or international) applications, and is configurable either as an VSAT (very small aperture terminal) using an SSPA, or as a larger station depending on the capacity requirements. A centralized DAMA processor and network manager is implemented using a workstation.
Earth System Environmental Literacy
Lowman, Margaret
If every citizen could read the above quote and understand its underlying ecological concepts, economic challenges, social services, and spiritual heritage, then it is likely that sustainability education would be achieved. The notion of a tree and its ecosystem services illustrate sustainability in the simplest yet most robust sense. To plant and grow a tree, economists struggle with volatile currencies; ecologists juggle development and conservation; religious leaders advocate stewardship; and social scientists examine equity in a world of declining resources. Sustainability education requires an integrated approach between ecology, risk analyses, economics, social sciences, biological sciences, political sciences, languages, biotechnology, physical sciences, health sciences, and religion. All these practitioners (and many others) contribute to sustainability education, an emerging discipline that requires an interdisciplinary synthesis of knowledge, translated into practice, to insure the future of life on Earth.
Cosmic rays and Earth's climate
DEFF Research Database (Denmark)
Svensmark, Henrik
2000-01-01
During the last solar cycle the Earth's cloud cover underwent a modulation in phase with the cosmic ray flux. Assuming that there is a causal relationship between the two, it is expected and found that the Earth's temperature follows more closely decade variations in cosmic ray flux than other...... solar activity parameters. If the relationship is real the state of the Heliosphere affects the Earth's climate....
Elkins-Tanton, Linda T
2010-01-01
The moon is the only body in the solar system outside of the Earth that has been visited by humans. More than 440 pounds of lunar material are brought by NASA and Soviet space missions to Earth for study. The information gleaned about the moon from this relatively small pile of rocks is mind-boggling and stands as the greatest proof that Martian planetary science would be greatly enhanced by returning samples to Earth. Compositional studies of lunar rocks show that the moon and the Earth are made of similar material, and because lunar material has not been reworked through erosion and plate te
Healing the Earth - Earth observation supporting international environmental conventions
Arino, Olivier; Fernandez-Prieto, Diego; Volden, Espen
2006-11-01
ESA is building long-term relationships with several user communities that can benefit from the Agency's Earth observation programmes. Since 2000, ESA has been working in close collaboration on three international environmental conventions. Here we see how its Earth observation activities are benefiting these conventions.
Modeling Earth Albedo for Satellites in Earth Orbit
DEFF Research Database (Denmark)
Bhanderi, Dan; Bak, Thomas
2005-01-01
Many satellite are influences by the Earthøs albedo, though very few model schemes exist.in order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view......, and that the longitude of the satellite position is significant to the model output. The results also show that the calculated albedo is generally lower than it would be expected based only on the reflectivity data....
Directory of Open Access Journals (Sweden)
Jihong Ye
2017-07-01
Full Text Available In this paper, a simple and effective numerical approach is presented on the basis of the Member Discrete Element Method (MDEM to investigate static and dynamic responses of steel frames with semi-rigid joints. In the MDEM, structures are discretized into a set of finite rigid particles. The motion equation of each particle is solved by the central difference method and two adjacent arbitrarily particles are connected by the contact constitutive model. The above characteristics means that the MDEM is able to naturally handle structural geometric nonlinearity and fracture. Meanwhile, the computational framework of static analysis is consistent with that of dynamic analysis, except the determination of damping. A virtual spring element with two particles but without actual mass and length is used to simulate the mechanical behaviors of semi-rigid joints. The spring element is not directly involved in the calculation, but is employed only to modify the stiffness coefficients of contact elements at the semi-rigid connections. Based on the above-mentioned concept, the modified formula of the contact element stiffness with consideration of semi-rigid connections is deduced. The Richard-Abbort four-parameter model and independent hardening model are further introduced accordingly to accurately capture the nonlinearity and hysteresis performance of semi-rigid connections. Finally, the numerical approach proposed is verified by complex behaviors of steel frames with semi-rigid connections such as geometric nonlinearity, snap-through buckling, dynamic responses and fracture. The comparison of static and dynamic responses obtained using the modified MDEM and those of the published studies illustrates that the modified MDEM can simulate the mechanical behaviors of semi-rigid connections simply and directly, and can accurately effectively capture the linear and nonlinear behaviors of semi-rigid connections under static and dynamic loading. Some conclusions
Environmental seismology: What can we learn on earth surface processes with ambient noise?
Larose, Eric; Carrière, Simon; Voisin, Christophe; Bottelin, Pierre; Baillet, Laurent; Guéguen, Philippe; Walter, Fabian; Jongmans, Denis; Guillier, Bertrand; Garambois, Stéphane; Gimbert, Florent; Massey, Chris
2015-05-01
Environmental seismology consists in studying the mechanical vibrations that originate from, or that have been affected by external causes, that is to say causes outside the solid Earth. This includes for instance the coupling between the solid Earth and the cryosphere, or the hydrosphere, the anthroposphere and the specific sources of vibration developing there. Environmental seismology also addresses the modifications of the wave propagation due to environmental forcing such as temperature and hydrology. Recent developments in data processing, together with increasing computational power and sensor concentration have led to original observations that allow for the development of this new field of seismology. In this article, we will particularly review how we can track and interpret tiny changes in the subsurface of the Earth related to external changes from modifications of the seismic wave propagation, with application to geomechanics, hydrology, and natural hazard. We will particularly demonstrate that, using ambient noise, we can track 1) thermal variations in the subsoil, in buildings or in rock columns; 2) the temporal and spatial evolution of a water table; 3) the evolution of the rigidity of the soil constituting a landslide, and especially the drop of rigidity preceding a failure event.
A Report of Contemporary Rammed Earth Construction and Research in North America
Directory of Open Access Journals (Sweden)
Arno Schmidt
2013-01-01
Full Text Available Contemporary stabilized rammed earth (SRE draws upon traditional rammed earth (RE methods and materials, often incorporating reinforcing steel and rigid insulation, enhancing the structural and energy performance of the walls while satisfying building codes. SRE structures are typically engineered by licensed Structural Engineers using the Concrete Building Code or the Masonry Building Code. The construction process of SRE creates structural walls of relatively high compressive strength appropriate for a broad range of heating and cooling climates. The incorporation of rigid insulation creates a high mass interior wythe that is thermally separated from the exterior, resulting in improved thermal performance. Modular aluminum reinforced formwork allows walls to be built without the use of through ties, common in concrete construction. The North American Rammed Earth Builders Association (NAREBA collaborated with Unisol Engineering Ltd. and the British Columbia Institute of Technology (BCIT on a battery of tests to obtain preliminary data to be used in support of engineering design. The tests included compressive strength comparisons, pull out rebar testing of both horizontally and vertically placed steel, simple beam tests, and the deflection of two composite wall columns with an insulation core and two types of reinforcing steel connections between the RE wythes.
Static elastic deformation in an orthotropic half-space with rigid ...
Indian Academy of Sciences (India)
Yogita Godara
2017-10-06
Oct 6, 2017 ... The solution of static elastic deformation of a homogeneous, orthotropic elastic uniform half-space with rigid boundary due to a non-uniform slip along a vertical strike-slip fault of infinite length and finite width has been studied. The results obtained here are the generalisation of the results for an isotropic.
A rigid-body least-squares program with angular and translation scan facilities
Kutschabsky, L
1981-01-01
The described computer program, written in CERN Fortran, is designed to enlarge the convergence radius of the rigid-body least-squares method by allowing a stepwise change of the angular and/or translational parameters within a chosen range. (6 refs).
Using simple shape three-dimensional rigid inclusions to enhance porous layer absorption.
Groby, J-P; Lagarrigue, C; Brouard, B; Dazel, O; Tournat, V; Nennig, B
2014-09-01
The absorption properties of a metaporous material made of non-resonant simple shape three-dimensional rigid inclusions (cube, cylinder, sphere, cone, and ring torus) embedded in a rigidly backed rigid-frame porous material are studied. A nearly total absorption can be obtained for a frequency lower than the quarter-wavelength resonance frequency due to the excitation of a trapped mode. To be correctly excited, this mode requires a filling fraction larger in three-dimensions than in two-dimensions for purely convex (cube, cylinder, sphere, and cone) shapes. At long wavelengths compared to the spatial period, a cube is found to be the best purely convex inclusion shape to embed in a cubic unit cell, while the embedment of a sphere or a cone cannot lead to an optimal absorption for some porous material properties and dimensions of the unit cell. At a fixed position of purely convex shape inclusion barycenter, the absorption coefficient only depends on the filling fraction and does not depend on the shape below the Bragg frequency arising from the interaction between the inclusion and its image with respect to the rigid backing. The influence of the incidence angle and of the material properties, namely, the flow resistivity is also shown. The results of the modeling are validated experimentally in the case of cubic and cylindrical inclusions.
Active zone impact on deformation state of non-rigid pavement
Mandula, Ján
2014-06-01
The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper
Active zone impact on deformation state of non-rigid pavement
Mandula Ján
2014-01-01
The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper
Active zone impact on deformation state of non-rigid pavement
Directory of Open Access Journals (Sweden)
Mandula Ján
2014-06-01
Full Text Available The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper
Efficacy of Semi-Rigid Ureteroscopy and Holmium:YAG Laser ...
African Journals Online (AJOL)
Background: Urolithiasis is a common worldwide health problem. Many endosurgical treatments became available for urinary calculi. Objectives: To find out the success clearance and complication rates of ureteric stone treatment using semi-rigid ureteroscopy and Holmium:YAG laser lithotripsy as a day case procedure.
Threat-rigidity effects on planning and decision making in teams
Kamphuis, W.; Gaillard, A.W.K.; Vogelaar, A.L.W.
2008-01-01
In an experimental study, the effects of external threat on team processes and performance were investigated during a complex planning and decision making task. Results showed that teams under threat suffered from rigidity effects in their information processing, leadership, team perspective and
Drainage of single Plateau borders: Direct observation of rigid and mobile interfaces
Koehler, Stephan A.; Hilgenfeldt, Sascha; Weeks, Eric R.; Stone, Howard A.
2002-01-01
Foam drainage varies with surfactant. We present direct measurements of the flow velocity profiles across single Plateau borders, which make up the interconnected channel-like network for liquid flow. For protein foams the interface is rigid, whereas small-surfactant foams show significant
Online learning and fusion of orientation appearance models for robust rigid object tracking
Marras, Ioannis; Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja
2014-01-01
We introduce a robust framework for learning and fusing of orientation appearance models based on both texture and depth information for rigid object tracking. Our framework fuses data obtained from a standard visual camera and dense depth maps obtained by low-cost consumer depth cameras such as the
Online learning and fusion of orientation appearance models for robust rigid object tracking
Marras, Ioannis; Alabort, Joan; Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja
We present a robust framework for learning and fusing different modalities for rigid object tracking. Our method fuses data obtained from a standard visual camera and dense depth maps obtained by low-cost consumer depths cameras such as the Kinect. To combine these two completely different
The motion of the rigid body in viscous fluid including collisions. Global solvability result
Czech Academy of Sciences Publication Activity Database
Chemetov, N.; Nečasová, Šárka
2017-01-01
Roč. 34, April (2017), s. 416-445 ISSN 1468-1218 R&D Projects: GA ČR GA16-03230S Institutional support: RVO:67985840 Keywords : rigid body * global weak solution * collisions in finite time Subject RIV: BA - General Mathematics Impact factor: 1.659, year: 2016 http://www.sciencedirect.com/science/article/pii/S1468121816301146
Sosef, M. N.; van Gulik, T. M.
2004-01-01
Total hepatectomy in animals provides an irreversible model of acute liver failure. Vascular reconstruction in this model of acute liver failure was modified and characterized for the use of assessment of liver support systems. Pigs underwent total hepatectomy and a rigid three-way transparent
Non-solid non-rigid optics for high-power laser systems
CSIR Research Space (South Africa)
Michaelis, MM
2006-06-14
Full Text Available Non-solid and non-rigid optics employ gas and liquid transmission and reflection, as well as flexible membranes to influence laser beams, laser driven particle beams and harmonic generators. Some examples are acoustic gratings, phase conjugate...
On integrability of a heavy rigid body sinking in an ideal fluid
DEFF Research Database (Denmark)
Deriabine, Mikhail; Hjorth, Poul G.
2003-01-01
We consider a rigid body possessing 3 mutually perpendicular planes of symmetry, sinking in an ideal fluid. We prove that the general solution to the equations of motion branches in the complex time plane, and that the equations consequently are not algebraically integrable. We show...
Ghalyan, Ibrahim Fahad Jasim
2016-01-01
This book provides comprehensive and integrated approaches for rigid and flexible object assembly. It presents comparison studies with the available force-guided robotic processes and covers contact-state modeling, scheme control strategies, and position searching algorithms. Further, it includes experimental validations for different assembly situations, including those for the assembly of industrial parts taken from the automotive industry. .
Constraints on the Computation of Rigid Motion Parameters from Retinal Displacements.
1985-10-01
observed, is due to a rigid surface. (ii) The time constant (or sampling interxal ) of the sensor is small enough to make a first order approximation...measurements that are actually made invol~e displacements o’er a small time interxal . This means the abo’.e ’elocit\\ equations, are not strictlN applicable
Motion of a Rigid Rod Rocking Back and Forth Cubic-Quintic Duffing Oscillators
DEFF Research Database (Denmark)
Ganji, S. S.; Barari, Amin; Karimpour, S.
2012-01-01
In this work, we implemented the first-order approximation of the Iteration Perturbation Method (IPM) for approximating the behavior of a rigid rod rocking back and forth on a circular surface without slipping as well as Cubic-Quintic Duffing Oscillators. Comparing the results with the exact...
Projected Gauss-Seidel subspace minimization method for interactive rigid body dynamics
DEFF Research Database (Denmark)
Silcowitz-Hansen, Morten; Abel, Sarah Maria Niebe; Erleben, Kenny
2010-01-01
In interactive physical simulation, contact forces are applied to prevent rigid bodies from penetrating and to control slipping between bodies. Accurate contact force determination is a computationally hard problem. Thus, in practice one trades accuracy for performance. This results in visual art......–Seidel method with a subspace minimization method. Our new method shows improved qualities and superior convergence properties for specific configurations....
Effects of Corneal Scars and Their Treatment With Rigid Contact Lenses on Quality of Vision
de Jong, Bram; van der Meulen, Ivanka J E; van Vliet, Johannes M J; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P; van den Berg, Thomas J T P
OBJECTIVES: To study the effects of corneal scars and the treatment of these scars with rigid gas-permeable (RGP) contact lenses on quality of vision including straylight. Visual effects were related to scar characteristics such as size and grade. METHODS: Straylight and best-corrected visual acuity
Bifunctional role of leucine 300 of firefly luciferase in structural rigidity.
Yousefi, Farzad; Ataei, Farangis; Mortazavi, Mojtaba; Hosseinkhani, Saman
2017-08-01
Firefly luciferase is susceptible to thermal inactivation, thereby its intracellular half-life decreased. Previous reports indicated that L(300)R mutation (LRR mutant) in E(354)R/Arg(356) double mutant (ERR mutant) from Lampyris turkestanicus luciferase has increased its thermal stability and rigidity through induction of some ionic bonds with Asp 270 and 271. Disruption of the deduced ionic bonds in an ultra-rigid mutant of firefly luciferase did not reverse the flexibility of the protein. In this study, we investigated the effects of this residue to find the truth behind an extraordinary increase in thermal stability and rigidity of luciferase after replacement of leucine 300 by arginine based on previous reports. For this purpose, L(300)R, L(300)K and L(300)E mutations were performed to compare the effects of these mutations on the native firefly luciferase. In spite of increase of intrinsic fluorescence of the mutants a slight increase in thermostability and retention of kinetic properties was observed. Based on our results, we can conclude that L(300)R mutation in LRR mutant accompanying with alteration in a flexible loop (352-359) increased thermostability and rigidity of luciferase. Copyright © 2017 Elsevier B.V. All rights reserved.
Budidaya Anggur Laut (Caulerpa Racemosa melalui Media Tanam Rigid Quadrant Nets Berbahan Bambu
Directory of Open Access Journals (Sweden)
Gede Ari Yudasmara
2015-01-01
Full Text Available Anggur laut (Caulerpa racemosa merupakan makro alga hijau yang sering dimanfaatkan sebagai makanan bagi masyarakat sekitar pantai. Akan tetapi ketersediaannya masih dalam jumlah yang sangat terbatas dan musiman, karena masih tergantung dari alam dan belum dibudidayakan secara baik dan benar. Untuk itu diperlukan usaha budidaya untuk menunjang kontinuitas produksinya. Penelitian ini bertujuan untuk mengkaji dan menganalisis efektifitas dan efisiensi rigid quadrant nets berbahan bambu dalam budidaya Caulerpa racemosa dan mengkaji kualitas dan kuantitas yang diperoleh dari penerapan rigid quadrant nets berbahan bambu dalam budidaya Caulerpa racemosa. Untuk mencapai tujuan tersebut dilakukan melalui penelitian eksperimen dengan rancangan pre test post test control group design. Hasil penelitian menunjukkan bahwa rigid quadrant nets berbahan bambu cukup efektif dan efisien dalam budidaya Caulerpa racemosa, begitupula dari segi kualitas dan kuantitas substrat rigid quadrant nets berbahan bambu cukup baik kualitasnya serta hasil panen sebanyak Bak I sebesar 2340,46 gram, Bak II sebesar 2003,60 gram dan Bak ke III sebesar 2135,5 gram dengan masa penanaman selama 42 hari.
The use of a test for neuroticism, extraversion and rigidity in Dutch immigrant groups.
te Nijenhuis, J.; van der Flier, H.; Leeuwen, van
2003-01-01
The questions addressed are whether a taxonomy with the basic dimensions Neuroticism and Extraversion and the dimension Rigidity can be generalised to immigrant groups in the Netherlands, and whether scores on the IRT (ICIP [Institute for Clinical and Industrial Psychology, University of Utrecht,
More accurate neuronavigation data provided by biomechanical modeling instead of rigid registration.
Garlapati, Revanth Reddy; Roy, Aditi; Joldes, Grand Roman; Wittek, Adam; Mostayed, Ahmed; Doyle, Barry; Warfield, Simon Keith; Kikinis, Ron; Knuckey, Neville; Bunt, Stuart; Miller, Karol
2014-06-01
It is possible to improve neuronavigation during image-guided surgery by warping the high-quality preoperative brain images so that they correspond with the current intraoperative configuration of the brain. In this paper, the accuracy of registration results obtained using comprehensive biomechanical models is compared with the accuracy of rigid registration, the technology currently available to patients. This comparison allows investigation into whether biomechanical modeling provides good-quality image data for neuronavigation for a larger proportion of patients than rigid registration. Preoperative images for 33 neurosurgery cases were warped onto their respective intraoperative configurations using both the biomechanics-based method and rigid registration. The Hausdorff distance-based evaluation process, which measures the difference between images, was used to quantify the performance of both registration methods. A statistical test for difference in proportions was conducted to evaluate the null hypothesis that the proportion of patients for whom improved neuronavigation can be achieved is the same for rigid and biomechanics-based registration. The null hypothesis was confidently rejected (p registration was rejected at a significance level of 5% (p = 0.02). The biomechanics-based method proved particularly effective in cases demonstrating large craniotomy-induced brain deformations. The outcome of this analysis suggests that nonlinear biomechanics-based methods are beneficial to a large proportion of patients and can be considered for use in the operating theater as a possible means of improving neuronavigation and surgical outcomes.
Coburn, Natalie; Beldham-Collins, Rachael; Westling, Jelene; Trovato, Jenny; Gebski, Val
2012-01-01
Protocols commonly implemented in radiotherapy work areas may be classified as being either rigid (class solution) or flexible. Because formal evaluation of these protocol types has not occurred within the literature, we evaluated the efficiency of a rigid compared with flexible prostate planning protocol by assessing a series of completed 3D conformal prostate plans. Twenty prostate cancer patients with an average age of 70 years (range, 52-77) and sizes comprising 8 small, 10 medium, and 2 large were planned on the Phillips Pinnacle treatment planning system 6 times by radiation therapists with 5 years of experience using a rigid and flexible protocol. Plans were critiqued using critical organ doses, confirmation numbers, and conformity index. Plans were then classified as being acceptable or not. Plans produced with the flexible protocol were 53% less likely to require modification (OR 0.47, 95% CI: 0.26, 0.84, p = 0.01). Planners with >5 years of experience were 78% more likely to produce plans requiring modification (OR 1.78, 95% CI: 1.12, 2.83, P = 0.02). Plans according to the flexible protocol took longer (112 min) compared with the time taken using a rigid protocol (68 min) (p plan is not reached, then flexibility should be given to improve the plan to meet the desired results. Crown Copyright Â© 2012. Published by Elsevier Inc. All rights reserved.
A field map guided approach to non-rigid registration of brain EPI to structural MRI
Gholipour, Ali; Kehtarnavaz, Nasser; Briggs, Richard W.; Gopinath, Kaundinya S.
2007-03-01
It is known that along the phase encoding direction the effect of magnetic field inhomogeneity causes significant spatial distortions in fast functional MRI Echo Planar Imaging (EPI). In this work, our previously developed distortion correction technique via a non-rigid registration of EPI to anatomical MRI is improved by adding information from field maps to achieve a more accurate and efficient registration. Local deformation models are used in regions of distortion artifacts instead of using a global non-rigid transformation. The use of local deformations not only enhances the efficiency of the non-rigid registration by reducing the number of deformation model parameters, but also provides constraints to avoid physically incorrect deformations in undistorted regions. The accuracy and reliability of the non-rigid registration technique is improved by using an additional high-resolution gradient echo EPI scan. In-vivo validation is performed by comparing the similarity of the low-resolution EPI to various structural MRI scans before and after applying the computed deformation models. Visual inspection of the images, as well as Mutual Information (MI) and Normalized Cross Correlation (NCC) comparisons, reveal improvements within the sub-voxel range in the moderately distorted areas but not in the signal loss regions.
Sternick, Marcelo Back; Dallacosta, Darlan; Bento, Daniela Águida; do Reis, Marcelo Lemos
2012-01-01
To analyze the rigidity of a platform-type external fixator assembly, according to different numbers of pins on each clamp. Computer simulation on a large-sized Cromus dynamic external fixator (Baumer SA) was performed using a finite element method, in accordance with the standard ASTM F1541. The models were generated with approximately 450,000 quadratic tetrahedral elements. Assemblies with two, three and four Schanz pins of 5.5 mm in diameter in each clamp were compared. Every model was subjected to a maximum force of 200 N, divided into 10 sub-steps. For the components, the behavior of the material was assumed to be linear, elastic, isotropic and homogeneous. For each model, the rigidity of the assembly and the Von Mises stress distribution were evaluated. The rigidity of the system was 307.6 N/mm for two pins, 369.0 N/mm for three and 437.9 N/mm for four. The results showed that four Schanz pins in each clamp promoted rigidity that was 19% greater than in the configuration with three pins and 42% greater than with two pins. Higher tension occurred in configurations with fewer pins. In the models analyzed, the maximum tension occurred on the surface of the pin, close to the fixation area.
Effects of flexible and rigid rocker profiles on in-shoe pressure
Reints, Roy; Hijmans, Juha M.; Burgerhof, Johannes G.M.; Postema, Klaas; Verkerke, Gijsbertus J.
2017-01-01
Rocker profiles are commonly used in the prevention of diabetic foot ulcers. Rockers are mostly stiffened to restrict toe plantarflexion to ensure proper offloading. It is also described that toe dorsiflexion should be restricted. However, the difference in effect on plantar pressure between rigid
The evolutionary basis of rigidity: Locks in cells, minds, and society
Scheffer, M.; Westley, F.R.
2007-01-01
Feedbacks leading to alternative stable modes of behavior occur on levels varying from the cell and the mind to societies. The tendency to lock into a certain pattern comes at the cost of the ability to adjust to new situations. The resulting rigidity limits the ability of persons, groups, and
Modelling of magnetorheological squeeze film dampers for vibration suppression of rigid rotors
Czech Academy of Sciences Publication Activity Database
Zapoměl, Jaroslav; Ferfecki, Petr; Kozánek, Jan
2017-01-01
Roč. 127, Jul SI (2017), s. 191-197 ISSN 0020-7403 R&D Projects: GA ČR GA15-06621S Institutional support: RVO:61388998 Keywords : squeeze film damper * magnetorheological fluid * bilinear material * rigid rotor * frequency response Subject RIV: JR - Other Machinery Impact factor: 2.884, year: 2016
Numerical study of interactions among air, water, and rigid/flexible solid bodies
He, Sida; Yang, Zixuan; Shen, Lian
2017-11-01
We develop a numerical method for simulating the fluid-structure interactions (FSI) among air, water, and rigid/flexible solid bodies. The influence of solid bodies on fluid flows is captured by an immersed boundary method. The air and water are simulated as a coherent system, with a coupled level-set and volume-of-fluid method implemented to capture the interface between air and water. Six degrees of freedom are considered for the motion of rigid bodies. A finite element method based on thin-shell theory is utilized to simulate the arbitrarily large deformation of flexible plates. Both strong coupling and loose coupling have been applied based on the density ratio of structure and fluid. We validate our code using benchmark cases with one-phase fluids, including the vortex-induced vibration of a rigid circular cylinder and the vibration of cantilever mounted behind a square cylinder caused by vortex shedding. We also test the accuracy of the code for simulating FSI problems with two-phase fluids in the context of barge floating at fluid interface and violent breaking waves impinging onto rigid/flexible plates. It is found that our simulation results are in good agreement with laboratory and simulation results reported in literature.
Sound penetration into a hard-backed rigid porous layer: theory and experiments.
Tao, Hongdan; Tong, Bao N; Li, Kai Ming
2014-08-01
This study examines the sound field within a hard-backed rigid porous medium due to an airborne source. The total sound field can be approximated by two terms: A transmitted wave component arriving at the receiver directly through the porous interface, and a second transmitted wave component reflected from the rigid backing plane before reaching the receiver. These two components can be expressed in an integral form that is amenable to further analyses. A standard saddle path method is applied to evaluate the integral analytically, leading to a uniform asymptotic solution that allows the prediction of the sound field within the rigid porous medium. The validity of the asymptotic formula is verified by comparison with the numerical results computed by a more accurate wave-based numerical scheme. The asymptotic solution is shown to provide a convenient means of rapid and accurate computations of sound field within the rigid porous medium. The accuracy of the numerical solutions is further confirmed by comparison with indoor experimental results. The measurement data and theoretical predictions suggest that when the receiver is located near the bottom of the hard-backed layer, the reflection of the refracted wave gives rise to a significant contribution to the total sound field.